CA2179272A1 - Hinges for highly inorganically filled composite materials - Google Patents

Abstract

A hinge for use in inorganically filled composite materials is provided. The hinge has an inorganically filled structural matrix comprising a water-dispersable organic polymer binder an aggregate material, and a fibrous material. The hinge allows inorganically filled materials to be bent along a line without breakage of the material. The hinge is preferably formed by scoring a formed sheet of inorganically filled material (50). The hinge is particularly useful in containers that require bending of various container parts, such as in food containers and boxes made from inorganically filled materials.

Description

wo 9S/21056 ` 2 1 ~ 9 2 7 2 I

~TN~F.~ FOR ~TIC.TTT Y INORGANICAl.I.Y
Fll~T~T~n col~lrposITE MATERIAl.

1. Fi ' ' of - - Tnvention The invention relates generally to hinges for use with highly jnr,r~nirsllly filled composite materials. More I~L~ulallr, the invention relates to a hinge integrally made in a highly " lly filled composite sheet, which can be formed into various containers or other products.

2. The 12~ ` T ' ' ~
A. ~hPPtC ~. 'C- r ~ r~
Thin, flexible sheets made from materials such as paper, p-~r~-rhr~r~l plastic, p~lJal~lc.lc, and even metals are presently used in enormous quantity as printedmaterials, labels, mats, and in the r ' of other objects such as containers, separators, dividers, envelopes, lids, tops, cans, and uth_. ~ materials. Advanced processing and packaging techniques presently allow an enormous variety of liquid and solid goods to be stored, packaged, or shipped while being protected from harmful elements.
Containers and other packaging materials protect goods from ~ ;IU.~
influences and ~lietrlhlltinn damage, u~Lc~ uly from chemical and physical influences.
Packaging helps protect an enormous variety of goods from gases, moisture, light, . u~ vermin, physical shock, crushing forces, vibration, leaking, or spilling.
Some packaging materials also provide a medium for the ~ ;"" of r to the consumer, such as the origin of . . --, r I . c~ contents, advertising, illaLI ~I~liu~
brandi~l t~ l;...,,andpricing.
Typically, most containers and cups (including disposable containers) are made from paper, paperboard, plastic, pOl~alJ.cl.., glass and metal materials Each year over ~5 100 billion aluminum cans, billions of glass bottles and thousands of tons of paper amd plastic are used in storing and dispensing soft drinks, juices, processed foods, grains, beer, etc. Outside of the food and beverage industry, packaging containers (and especially disposable containers) made from such materials are ubiquitous. Paper for printing, writin~ pl~u~u-,u~ , magazines, Il~.~a~ la~ bûûks, wrappers, and ûther flat WO 951210~6 21 792 72 ~ --S items made primarily from tree derived paper sheets are also ~ lur~d each year in enormous quantities. In the Urlited States alone, ~UUII ' ' Iy 5 1/2 million tons of paper are consumed each year for packaging purposes, which represents only about 15%
of the total annual domestic paper production.
B. r r~ ~
The general term "paper" is used for a wide range of matted or felted webs of vegetable fiber (mostly wood) that have been formed on a screen from a water suspension. The sheet materials that most people refer to as "paper" or "~u~u~"bu~d" are generally "tree paper" because these materials are ~ ~ from wood pulp derived from trees. Although tree paper may mclude inorganic fillers or extenders, starches, or other minor ~ it will typically contain a relatively high wood fiber content, generally from about 80% to as high as 98% by volume of the paper sheet.
Tree paper is " ~f~ r-1 by processmg wood pulp to the point of releasing the ligrlins and l " ' ~ of the raw wood pulp fibers, as well as fraying and fracturing the fibers themselves, in order to obtain a mixture of fibers, lignins, and h~-nnir~ rq.- tbat will be essentially self-bmding through web physics. The broad category of cellulose-based paper, mainly plant, vegetable, or tree paper, will hereinafter collectively be referred ~o as '',,v..~ iu..~l paper."
The properties of an individual w~lv~ tiu~l paper or paperboard are extremely dependent on the properties of the pulps used. Pulp properties are dependent on both the source amd the processing technique(s) used to prepare the pulp for paper-making. For example, coarse packaging papers are almost always made of unbleached kraft softwood pulps. Fme papers, generally made of bleached pulp, are typically used in s~rplif :ltinnc demanding printing, writing, amd special functional properties such as bar~iers to liquid and/or gaseous penetr~mts.
Cu..~ iull~l paper is typically r ' cd by creating a _ighly aqueous slurry, or furnish, which is then ' 'ly dewatered by first placimg the slurry on a porous screen or wire sieve and then "~ l ~ L' 'L" out the water using a roller nip. This frst dewatering process results in a sheet having a water content of about 50-60%. Af~er tbat, the partially dried paper sheet is further dried by heating the sheet, often by means of heated rollers. Because of the paper . " " ~ r l . .g prûcess, as well as the limitations imposed by web physics, there has been an upper limit of the amount of inorganicaggregate fillers than can be i...u.~ within a conventional paper sheet.

~ wo gS/21056 2 1 7 g 2 7 2 . 1/. s l In order to obtain the well-known properties that are typical of paper, substitute fibrous substrates have been added instead of wood derived fibers. These include a variety of plant fibers (known as "secondary fibers"), such as straw, flax, abaca, hemp, and bagasse. The resultant paper is often referred to as "plant paper". As in tree paper, plamt paper relies on web physics, highly processed fibers, and highly aqueous fiber slurries in its IllalluL~,~ulc.
C. Th~l of rL .r- r ~ r~ ~
A huge variety of objects such as containers, packing materials, mats, disposable utensils, reading or other printed materials, and decorative items are presently mass-produced from paper, cardboard, plastic, polystyrene, and metals. The vast majority of such items eventually wind up within our ever ~ landfills, or worse, are scattered on the ground or dumped into bodies of water as litter.
Since plastic and pOI.~ are essentially ~ ,lr they persist within the larld and water as unsightly, value ~' ' _ and (in some cases) toxic O foreign materials. Even paper or cardboard, believed by many to be 1.:- d~ lP can persist for years, even decades, within landfills where tbey are shielded from air, light, and wâter, which are all necessary for normal 1 - -~ activities. Metal products utili~e valuable natural resources in their r ' _, and if not recycled, remain in the landfill and are unusable essentially forever.
s Recently there has been a debate as to which of these materials (e.g, paper, cardboard, plastic, ~Joly~ c, glass, or metai) is most damaging to the e llvuUI~I..lL.
('..,.~. ;.. -- . raising ~ have convinced mamy people to substitute one material for another in order to be more ~ ilUIUll. Il~lly "correct." The debate often misses the point that each of these materials has its own unique ~IIVU~ ' ~
. . ' One material may appear superior to another when viewed in light of a par-ticular ~llvlll ' problem, while ignoring different, often larger, problems associated with the ~ulJIJv~lly preferred materiai. In fact, paper, cardboard, plastic, ~UI.~ yl~."
glass, and metal materials each have their own unique C..V;I ~ I ~ I The debate should, therefore, not be directed to which of these materials is more or less hatmful to the ~llvhul~ llL, but should rather be directed toward asking: Can we find an altemative material that will solve most, if not all, of the various C~IV;lUlllll~
problems associated with each of these presently used materials?
With the public's attention being focused on ~llv;ll ' issues, cerLam C.. ~ products have come under heavy scrutiny, especially dispûsable packing WO 95/21056 2 1 7 9 2 7 2: r~l~o s . ~

S materiais and boxes. rolya~y~ c products have more recently attracted the ire of ellvilVll~ ,l~l groups, ~JalLi~ uly containers and other pacicaging materiais. While polya~ylLll~ itself is a relatively inert substance, its ,. . ,., r ~ r involves the use of a variety of hazardous chemicals and starting materials. ~ll"ul~lll~,l;~ styrene is very reactive and therefore presents a health problem to those who must handle it. Because styrene is lll~lur~ ulcd from benzene (a i~nown mutagen and probably a carcinogen), residual quantities of benzene can be found in styrene.
Most notably subject to criticism have been styrofoam products, wilich typicailyrequire the use of chioro-r~ - - ~, - 1,....~ (or "CFC's") in their 1. , r l, .. ~, as well as use of vast amounts of the ever shrinking petroleum reserves. In the Illa~ r~l~uc of foams, includingstyrofoam(orblownpc,lJi.~y.~ ),CFC's(whicharehighiyvolatileliquids)are used to "puff' or "blow" the pUiJ:liy.~ . which is then molded into foam cups and other food containers or paci~ing materials. 1~ " CFC's have been liniced to the destruction of the ozone layer, because they release chiorine products into the . ' ~.. Even the sllh~tihltil~n of less "ellvilull~ .ltally damaging" blowing agents 2û (e.g, HCFC, CO~, and pentanes) are still si~lIrl~l~l~ harmful and their . 1:.. ,:. :
wouid be beneficiai.
As a result, there has been widespread clamor for compalues to return to using more ..ll~ih. 'ly safe and low cost containers. Some eLlVil~ ' " ' have even favoredareturntomoreextensiveuseofpaperproductsinsteadofpC~l~DLy~cll-, if only because it is thought by some that paper represents the lesser of two evils. N.. ~ ~. 11l. 1~;, "
although paper products are ostensibly I 1~ L;' ..1 ' .1~ and have not been liniced to the destruction of the ozone layer, recent studies have shown that the ~ - - . r~ l - c of paper probably more shongly impacts the ~IIV;IUIIIII~ than does the r of In fact, the wood pulp and paper industry has been identified as one of the fivetop polluters in the United States. For instance, products made from paper require ten times as much steam, fourteen to twenty times the electricity, and twice as much cooling water compared to an equivalent puly ~ylCII~. product. Various studies have shown ~hat the effluent from paper ... . ~ contains ten to one hundred times the amount of ~ producedinthe r ' c ofpOIya~ylcllcfoam.
Anotherdrawbackofthell~..,r~iulcofpaperandpaperboardistherelatively large amount of energy that is required to produce paper. This includes the energy required to process wood pulp to the point that the fibers are aùrr~ y delignified and fray so that they are essentiaily self-binding under the principles of web physics. In ~N095121056 ~,~ '7 g 2~ 2 r~l" ~.~
addition, a large amount of energy is required in order to remove the water within Cullv~ .iul~dl paper slurries, which contam water in amount of up to about 99.5% by volume. Because so much water must be removed from the slurry, it is necessary to literally suck water out of the slurry even before heated rollers can be used to dry the sheet. Moreover, much of the water that is sucked out of the sheets during the dewatering processes is usually discarded into the ~IIV;IUI~ l. This process, which has changed little in decades, is energy mtensive, time enn~lmnin~, and requires a significarlt initial investment.
Further, it is often necessary to coat many paper containers with a wax or plastic material in order to give the containers ~ ,.,UIUUfill~ properties. Moreover, if insulative properties are necessary, even more drastic ",.~,1;1;. -l;.. to the paper material in the container are necessaly. Many types of plastic containers as well as coatirlgs utilized with paper containers are derived from fossil fuels, maiuly petroleum, and share many of the CIIVIIUIIIII~ I conccrns of petroleum refinr ~r t Paper u~ .b. - ~1, believed by many to be ~ U l ~ , can persist for years, even decades, within landfills where they are shielded from air, light, arld water -- all of which are required for normal 1.;...1. ,.., .1,-;.... activities. There are reports oftelephone bûoks and ~ having been lifted from garbage dumps that had been buried for decades. This longevity of paper is further, I " ' since it is common to treat, coat, or impregnate paper with various protective materials which further slow or prevent ,i. ~, .1 .. ;,, Another problem with paper, paperboard, ~OIJ ~ , and plastic is that c-ach of these requircs relatively expensive orgaluc starting materials, some of which are nu.,. GIl~, w~l~ such as the use of petroleum in the . . . - - ~ , of pol,~ l cll~. and plastic.
Although trees used in making paper and paperboard are rcnewable in the strict sense of the word, their large land . C.. l~ and rapid depletion in ccrtain areas of the world this notion. Hence, the use of huge amourlts of essentially ~
starting materials in making shcets and objects therefrom carmot be sustained and is not wise from a long term perspective.
r. - c, the processes used to make the packaging stock raw materials (such as paper pulp, styrene, or metal sheets) are very energy intensive, cause major amounts of water and air pollution, and require sigluficant capital , ~ t~. The , - . r . I ... ;.~"~ processes of plastic sheets or products vary, but they typically require precise control of both t~lll,u~,lalul~ and shear stress in order to make a usable product.

WO95121056 ~ 9~7~ r~"~
In addition, the typical p~ cll. or plastic . ., - -, r 1 . - ;. .~ process is a high consumer of energy.
The ..~. r~ r.; æ processes of forlning metal sheets mto containers / cans made of aluminum and tin), blowing glass bottles, and shaping ceramic containers utilize high amounts of energy because of the necessity to melt and then separately work and shape the raw metal into an ;,.~ . or fmal product. These high energy and processing Icyuhcl~ not only utilize valuable energy resources, but they also result in significant air, water, and heat pollution to the ~.IIVhV. 1.,11~. While glass can be recycled, that portion that ends up in landfills is essentially non-d~
Broken glass shards are very dangerous and can persist for years.
About the only effective way to reduce the shear volume of traditional containerand packing wastes is through recycling. Recyclmg is not, however, without its ~.. f ,l - ';-...oflargeamountsofpollutionintothe-l.vh~ intheforrnoffuelspent in ~ recyclables to recycling centers, as well as fuels and chemicals used in the recycling process itsel While sigluficant efforts have been expended in recycling programs, only a portion of the raw material needs come from recycling--most of the raw material still comes from nvlllcll~v~le resources.
In spite of the more recent attenhion that has been given to reduce the use of the above materials, they continue to be used b=e of their superior properties of strength and, especially, mass ~JIvdh~Liv;ly. Moreover, for any given use for which they were designed, such materials are relatively ihl~ ' t, easy to mold, strong, durable, and resishant to ~I~ c 1-~ ;.... during the use of the object in queshion.
D. 1 r~ ~
Essenhially ...~ morganic materials such as clay, natural minerals, or stone have been used for millemlia. Clay has found extensive use because of its ready moldability into a varietv of objects including containers, tiles, and other useful objects.
Someofthedrawbacksofclaymcludethetimeittakesforclaytoharden,theneedtofre or sinter clay in order to achieve optimum strength properties, and the generally large, heavy, and bulky nature of clay. Unfired clay, in particular, has low tensile strength and is very brittle. N~ , clay has found some use m the r ' C of other materials as a plentiful, ' ' ' and low-cost f ller, such as in paper or r~r~rbr.~
However, because of the brittle and non-cohesive nature of clay when used as a filler, clay has generally not been mcluded in amounts greater than about 20% by weight of the - overall paper material.

~ WO95/21056 ~ 92~ J~
S Stone has been used in the IllallllL~ lulc of buildings, tools, containers, and other large, bulky objects. An obvious drawback of stone, however, is that it is very hard, brittle, and heavy, which limits its use to large, bulky objects of relatively high mass.
Ne~ lc.~, smaller or crushed stone can be used as am aggregate material irl the ~i of other products, such as h~ llaul;~,ally settable, or f .. 1 ;1 ;.. ~ materials.
Hy~ / settable materials such as those that contain hydraulic cement or gypsum (hereinafter "Il~.La.ll;~,ally settable," "hydraulic," or "~ "
c ~ materials, or mixtures) have been used to create useful, generally large, bulky structures that are durable, strong, and relatively ill~AlJ.,1..7;~.,. For example, cement is a hydraulically settable binder derived from clay and limestone, amd it is essentially ~ lr Those materials containing a hydraulic cement are generally formed by mixing hydraulic cement with water and usually some type of aggregate to form a ~ mixture, which hardens into concrete. Ideally, a freshly mixed ~.. ~;1 .. mixture is fairly nonviscous, semi-fluid, and capable of being mixed arld formed by hand. Because of its fluid nature, concrete is generally shaped by being poured into a mold, worked to eliminate large air pockets, and allowed to harden. If the surface of the concrete structure is to be exposed, such as on a concrete sidewalk, additional efforts are made to finish the surface to make it more functional and to give it the desired surface ..l . --, ~. . ;-1;. ~
Due to the high level of fluidity required for typical ~ . .1;l ;- ~ mixtures to have adequate ~. ' ' ~' ~/, the uses of concrete and other LJ~ / settable miAtures have been limited mainly to simple shapes which are generally large, heavy, arld bulky, and which require mechanical forces to retain their shape for an extended period of time urltil sufficient hardening of the material has occurred. Another aspect of the limitations oftraditional- - ..1;1;.- ~mixturesorslurriesisthattheyhavelittleornoformstability and they are molded mto final form by pouring the miA~ure imto a space havmg extemally supported boundaries or walls.
It is precisely because of this lack of moldability (which may be the result of poor ~ . Jlkab;l;~y and/or poor form stability), coupled with the low tensile strength per unit weight, that L~dla~ àlly settable materials have Ll~;;iullally been useful only for 3s ~ where size and weight are not limiting factors and where the forces or loads exerted on the concrete are generally limited to cu~l,lc~ forces or loads, as in, e.g., roads, r.- . ~ sidewalks, and walls.
Moreûver, previous hydraulically settable materials have been brittle, rigid, ur~able to be folded or bent, and have low elasticity, deflection and flexural strength. The WO95/21056 ~1792 72 r~

brittle nature and lack of tensi~e strength (about 1-4 Mpa) in concrete is L~b;~lui~u~A~ly illustrated by the fact tbat concrete readily cracks or fractures upon the slightest amount of shrinkage or bending, unlike other materials such as metal, paper, plastic, or ceramic.
('" `~'1' .,11~, typical hydraulically settable materials have not been suitable for making small, lightweight objects, such as containers or thin sheets, which are better if made lû from materials with much higher tensile and flexural strengths per unit weight compared to typical 1.~.' ' 'ly settable materials.
Another problem with traditional, and even more recently developed high strerlgth concretes has been the lengthy curing times almost universally required for most concretes. Typical concrete products formed from a flowable mixture require a hardening period of 10-24 hours before the concrete is m~-rhAniAslly self-supporting, and upwards of a monlh before the concrete reaches a substantial amoumt of its maximum strength. Extreme care has had to be used to avoid moving the hydraulically settable articles urltil they have obtairled suff~cient strength to be demolded. Movement or demolding prior to this time has usually resulted irl cracks amd flaws in the hydraulically settable structural matrix. Once self-supporting, the object could be demolded, although it has not typically attained the majority of its ultimate strength umtil days or even weeks later.
Since the molds used in forming ll.yll~l;~ll.y settable objects are generally reused in the production of concrete products and a substantial period of time is required for even minimal curing of the concrete, it has been diffcult to ~ - 'ly and mass produce L~ Iy settable objects. Although zero slump concrete has been used to produce large, bulky objects (such as molded slabs, large pipes, or bricks which are; ' 'y self- .. _) on am rc . . .i Ally ~ -1 scale, such production is only useful in producing objects at a rate of a few thousand per day.
Such - . and methods cannot be used to mass produce small, j' " .1 .
objects at a rate of thousands per hour.
Demoldmg a llyl' ' 'Iy settable object can create further problems. As concrete cures, it tends to bond to the forms unless expensive releasing agents are used It is often necessary to wedge the forms loose to remove them. Such wedgmg, if not done properly and carefully each time, often results in cracking or breakage around the edges of the structure. This problem further limits the ability to make thin-walled ll.lL~Auli~ally settable articles or shapes other than flat slabs, ~. Li~.~AIcul y in any type of a, ...,..,.. ~: 1 mass production.

WO 95/210s6 ~ 7 ~ r~
If the bond between the outer wall of the molded hydraulically settable article and the mold is greater than the internal cohesive or tensile strengths of the molded - alticle, removal of the mold will likely breaic the relatively weak walls or other structural features of the molded article. Hence, traditional hydraulically settable objects must be large im volume, as well as ~,AIl~lu~ u;ly simple in shape, in order to avoid breakage during demolding (urless expensive releasing agents and other ~ are used).
Typical processing techniques of concrete also require that it be properly ~ ' ' after it is plæed in order to erlsure that no voids exist between the forms or irl the structural matrix. This is usually ~ d through various methods of vibration or poking. The problem with c~nenii~i~finE, however, is that extensiveu . ~.1 ./;bl~liUII of the concrete after it has been plæed can result in r~PEr' -g~ n or bleeding of the concrete.
"Bleeding" is the migration of water to the top surface of freshly placed concrete caused by the settling of the heavier aÆregate. Excessive bleeding increases the water to cement ratio near the top surfæe of the concrete slab, which ~ rl~y weakens 20 . andreducesthedurabilityofthesurfaceoftheslab. Theu._.wu.l.h.~ofconcreteduring the finishirlg process not only brings an excess of water to the surface, but also fine material, thereby resulting in subsequent surfæe defects.
Although hydraulically settable materials have heretofore found ~UIIIIII~
application only in the Ill~ llC of large, bulky structural type objects, L~/dlaulil ally settable miAtures have been created usmg a uauuclu~ . approach which can be molded or shaped mto relatively small, ti ~ Pd objects. Indeed, such mixtures, which were developed by the inventors hereof, have been fourld to be highly moldable and can be extruded and/or rolled into ' .. 'IPd sheets, even as thin as 0.1 mm. Such mixtures and methods used to r c sheets therefrom are set forth more fully in copending U.S. Patent Application Serial No. 08/101,500, entitled "Methods and Apparatus for r ~ r ,, Moldable HylL~uli.,dlly Settable Sheets Used in Making Containers, Printed Materials, and Other Objects," filed August 3, 1993 (hPrPins~f~Pr the "Andersen-Hodson Tc~,l.,.olo~Y").
Although the hydraulically settable binder is believed to impart a sigluficant amount of strength, including tensile and (especially) Culll~ aa;Vc strengths, such materials have been found in lower quantities to act less as a binding agent and more like an aÆregate filler. As a result, studies have been conducted to deterrnine whether sheets which do not necessarily use a hydraulically settable binder (or which only use such a binder in low enough quarltities so that it will act mainly as an aggregate material) but 21~g272 WO 951210~6 r~ 5 '1 S which incorporate high ~ of inorganic material can be ~ uf~Lulcd. Such sheets would have the advantages of hydraulically settable sheets over prior art paper, plastic, and metal materials im terms of their low cost, low ~ IIUIIII ~,lltal impact"md the ready availability of abundant starting materials.
Due to the more recent awareness of the 1. r . ~ ilul.lll~llL~l impacts of using paper, r~rcrbo ~i plastic, ~ a~lcll., and metals for a variety of single-use, mainly disposable, items such as printed sheets or containers made therefrom (not to mention the ever mounting political pressures), there has been an acute need (long since recognized by those skilled in the art) to find ~IIV;I~ / soimd substitute materials.
In particular, indust~y has sought to develop highly innr~anir -lly filled materials for these high waste volume items.
In spite of such economic and .Il~..ul~ L~l pressures, extensive research, and the associated long-felt need, the technology simply has not existed for the economic and feasible production of highly; ... ,. y,,, .. ~ filled, organic polymer bound materials which could be substituted for paper, rArrr~r ~ i plastic, pol~ .. l.., or metal sheets or container products made therefrom. Some attempts have been made to fill paper v~ith inorganic materials, such as kaolin amd/or calcium carbonate, although there is a limit (about 20-35% by volume) to the amount of inûrganics that can be ill.~, ' into these products. In addition, there have been attempts to fill certain plastic packaging materials with clay in order to increase the ~ ;ly of the product and improve the ability of the packaging material to keep fruits or vegetables stored therein fresh. In addition, inorganic materials are routinely added to adhesives and coatings in order to impalt certain properties of color or texture to the cured product.
lLll~ a~morganicmaterialsonlycompriseafractionoftheoverallmatelia used to make such products, rather than making up the majority of the packaging mass.
Because highly inrr~anir~lly filled materials essentially comprise such .,llVil~neutral ~ as rock, sand, clay, and water, they would be ideally suited from an ecological standpoint tc replace paper, paperboard, plastic, pol~,L~I~Ile~ or metal materials as the materiai of choice for such ~ Inorganic materials also enjoy a large advamtage over synthetic or highly processed materiais from the standpoint of cost.
Inorganic materials not only use significant amounts of 1~ ~ 1 1 1 I'l if' they do not impact the ~ ilulllll~ t ne~rly as much as do paper, paperboard, pla~tic, ~!JUI~aLyl~ .~, or metal. Another advantage of; - ~ ly filled materials is that ~ wo 95121056 2 ~ ~ ~ 2 ~ 2 , ~1/. 5 1 they are far less expensive than paper, paperboard, plastic, p~l~ ,L~ , or metals.
T, ~ filled materials also require far less energy to ~ . . r ~ c.
- Ba-~ed on the foregoing, what is needed are improved ~.. 1.. ,~;1;.. ~ and methods for ...-- -r ~ highly; - t;~ filled organic polymer mixtures tbat can be formed into sheets and other objects presently formed from paper, p-r~-rb-p~ yl~illc, plastic, glass, or metal.
It would be a significant illlUlU.. ' in the art if such ç"-,-l-v~:l;-- .. and methods yielded highly i...~ filled sheets which had properties similar to paper, paperboard, pOI,~ lCll~, plastic, or metal sheets. It would also be a Lcll~ duu~a.l~ in the art to provide cnrnrn-.~innr~ and methods which allow for the production of highly ~ "S/ filled sheets having greater flexibility, tensile strengtb, toug~mess, ~ lddlJ;li~, and mass-rro~ ihility compared to materials having a high content of inorganic filler.
In addition, it would be a significant illl,UlU~_III~,II~ in the art if such sheets, as well as containers or other objects made therefrom, were readily degradable intosubstances which are commonly found in the earth. It would also be a 1,., .~1. ~illlUlU V~ m the art if such sheets could be formed into a variety of containers or other objects using existing ~ g equipment and techniques presently used to form such objects from paper, paperboard, polJi,i~lcl.e, plastic, or metal sheets.
Many containers, which can be formed withûut the need for amy bending ûr folding, are readily adaptable to be l~ r- 1 ~ l from inoreanic materials. Theseinclude plates, cups, utensils, etc. Many other types of containers such as boxes, clamshells, etc., however, require a material tbat c_n be bent and/or folded to form the desired shape and still be Culll~ ., in e,ost to r ~ Accordingly, what is needed is a hinge adapted for use with an; ~ ~O ~ filled material and, more ~ ' ~S~, a hinge that can be mtegrally formed as part of a sbeet of; ~ filled material that permits the sheet to be bent or folded into various c~ r;~ to form a variety of types of containers.
Hinges Icnown as "living hinges" have been used in the past on various plastic molded products. A living hinge may be bent multiple times without brealcage or fracture of the hinge materiaT.. Living hinges have been formed from soft, flexible 1l .. ,1,l , ;, elastomers that exhibit high endurance to flexural fatigue. Living hinges c~m take various shapes and have been used on various plastic molded parts to provide pivotal movement between adjacent rigid parts.

WO 95121056 F~~
2~ 79272 Scoring is a technique that has been used to proYide memory to sheet materials, such as paper-based materials, so that they bend m the same place along the scoring Ime.
These materials are bent toward the score. Scoring of a paper-based material damages the fibers at the score, making the material weaker in the area of the score, which provides for the bending of the material along the score. Scoring has been used on various products such as on cardboard boxes to provide bendable flaps to close the box, foldable garne boards, file folders, etc.
Scoring an ,.. ~".. ~.y filled material to produce a hinge for bendmg of thematerial has not been heretofore possible since such a material was previously too thick or too brittle to provide an effective bendmg point without breaking.
Therefore, theR is a need for a hinge for innr~sni~ glly filled materials that is at least as good as hinges used on priorpaper or plastic products in order to produce various containers having e_sily bendable portions. Such a hinge is disclosed and claimed herem.
SUMMARY OF TJ~. 1NVFl~TION
The present invention is an apparatus ~mrriqinp a hinge formed of a highly l~y filled composite matrix. The in~r~sn;.~r~lly filled composite matrix comprises a water-dispersable organic polymer binder, an aggRgate material, and a fibrous material. The inorganic , have a ~ in the range of about 40% to 98% by volume of the total solids m the matrix.
The invention also includes an apparatus comprising a first member, a second member adjacent to the first member, and means for flexibly joining the first and second members so that the first and second mernbers can be pivotally moved about Ihe joining means relative to one another. The joining means has an in- rgPrlirolly filled structural matrix comprising a water-dispersable organic polymer binder, an aggregate material, and a fibrous material. The joining means allows the first and second members to be pivotally moved between a fust position wherein the first and second members are in s~raight alignment with one another and a plurality of uth. . I,u .;Lull, wherem the first and second members form arl angle in relation to one another.
The inf r~pr,irr~lly filled materials used herein can generaly be described as mUlti-~ r t, multi-scale, fiber-reinforced, micro-cnmr~qitpq By carefully ;Il~,vl,uul~Lllg a variety of different materials (including inorganic aggregates, organic polymers, and fibers) capable of imparting discrete yet :SJ~ dlly related properties, it is possible to create a unique class or range of micro-composites having remarkable ~ wo 95/21056 % ~ ~ 9 ~ ~ 2 ~ S ~

properties of strength, toughness, .~IIV UVIIIII.~IL-I soundness, m-ss-l.ludu~;lJ;l;~y~ and low cost.
In particular, such materials can be used to Ill_lu~ uc sheets and hinges that can be used ' ~y to form a variety of objects such as containers or other packaging materials. Alternatively, such sheets can be rolled on to large spools or cut into sheets and stacked on a pallet and stored until needed. l hereafter, the stacked or rolled sheets may be cut and formed into the object of choice. Ihe sheets can be1~:""' .t~ ... d in order to introduce additional flexibility and elongation into the sheet to avoid splitting or cracking while being formed into the desired object.
Moreover, because the highly; ~y,r l _lly filled sheets and binges used m the present invention comprise more ~ llul~ ~lly friendly ~ the ".. r . ~
of such sheets and hinges impacts the ~1l V UUI~ll. llL to a much lesser extent than does the urrcL~c of other materials.
Although the highly ;....... c~. -lly filled sheets may also include organicsuch as cellulose-based fibers and an organic binder, such ~ . .t~
represent a much smaller fraction of the overall mass of the sheets compared to paper, and together v-ill make up usually less than about 60% by volume of the total solids of the hardened , "~/ filled sheet. In most cases, it will be preferable for fiber to be included in an amount from about 0.5% to about 50%. I`he organic polymer binder will preferably be included in amount in the range from about 1% to about 50% by volume of the total solids of the hardened sheet.
The binding forces impalted by the water-dispersable organic polymer bmder provide the majority of the tensile and flexural strengths within the sheets and hinges.
To a lesser extent the organic polymer binder may also interact with cert-in inorganic aggregate particles and fibers. The result is the ability to include far less fiber within the ; .. , ær : ~ filled matrix while ,, the beneficial effects of tensile strength, tear and burst strength, and flexibility imparted by the fibers. Employing less fiber while ..,-,..:-....~ good strength properties allows a more ~-."...: 1:~ produced sheet or container (as compared to paper) because (I) fiber is typically far more expensive than the inorganic filler, (2) the capital investment for the processing ecluipment is much less, and (3) , the fiber content also reduces the amount of organic ,.~.,.. 1.",, disposed of into the ~IIV;IUII~II
Unlike the Illrulur~.,L~c of plastic or polystyrene, highly ;..--~ ly filled sheets and hinges utilize little or no petroleum-based products or derivatives as starting n;aterials. Thus, althou~h sûme _mount of fossil fuel is nee,essaly to generate the energy wo95/21056 ~ 272 --S used in ' _ the highly innrgJPrlirqlly filled sheets, only a fraction of the petroleum used in the ~ of pol.~aL~cll~ or plastic products will be consumed overall. In addition, the energy , of tne present invention are much less than the energy I _ . of paper .,, ... r,.. I . ; . ,~ where extensive dewatering is necessary.
FinaUy, another advantage of the highly imlr~q~ iy filled sheets and hinges of the present invention (as well as containers or other objects made therefrom) is that their disposal impacts the ~IIVLIU~ far less than paper, paperboard, plastic, polys-tyrene, glass, or met~ products. The highly in~lrv,qn;rolly fiUed materials of the present invention are both rea~iily recyclable and, even if not recycled, will readily degrade when exposed to moisture, pressure, and other ~llv . . U...l~ forces into a fine vr_nular powder that has a c~ y to the CCvlllu~ of the earth. The U ,~ process is not dependent on ~ forces but will occur as a result of various natural forces that may be present, such as moisture and/or pressure.Th~ hinge ofthe present invention can be made in in~lrg~qn;rolly filled sheets that cqn be ' '~, used to form a variety of objects such as food or beverage containers, or can be stacked or rolled and stored for future use. Stored sheets can be 1-.. ;~1.. 1 in order to introduce additional flexibility and elongation therein to avoid splitting or craclcing when am object is formed.
The hinge of the invention can be ~I~ v~ly formed during the sheet ~Pv process by scoring, creping or perforating a formed intlrg5-n;rqlly filledsheet, which aids in forming a bend or hinge at a I ' ' location within the sheet.
The score can be cut or pressed into the surface of the sheet anytime after the sheet is formed in order to create a Iine within the structural matrix upon which the sheet can later be bent. Thus, the scorc can be molded between two parts of a mold, pressed into the sheet while wet or in a semi-hardened state, or the score can be cut into the sheet after the sheet has become fully dried. For example, a flat sheet can be scored and formed into the shape of a container and then hardened, or can be aUowed to harden and then scored and fommed into the shape of a container. The time and location of the placement of a score, score cut, or perforation will depend upon the desired purpose of the score and the properties of the inl~rgpnirolly filled material in question.
The scored sheet preferably bends away from the score, which is different from paper-based materials that bend toward the score. F- .1. .. ..., the hinge area of the sheet at the score actually becomes stronger as a result of the 1~ '; - of the in~gPn;rolly filled material at the score.

wo 95121056 ~ 1 7 '~ 2 7 2 S In addition, coatings can be applied to the surface of the sheet to p~ .ll~l. .. :ly soften and enhance the flexibility or elastic modulus of the sheet or a hinge area within the sheet. Eiastomer, plastic, or paper coatings can aid in preserving the integrity of the hinge whether or not the underlying harderled structural matrix fractures upon bending at the hinge.
During the subsequent process of forming the sheet into the shape of the desiredobject, it will usually be a.l~ v~w to remoisten the hardened sheet in order to Lu~ ulal;ly increase the flexibility and wulh~lhil;~y of the sheet. This is u~ Li~ulafly true in the case where the sheet will be rolled or has been scored arid is expected to mahe a ,Ufl;' ' 'y sharp bend during the container forming stage.
The hinge of the invention may be used in a variety of containers such as boxes,clamshell containers, etc. The hinge of the invention formed by scoring can have a cross section with a variety of shapes such as a square, parabolic, simusoidal, wedge, triangular shape, etc. Multiple scores may be used in order to provide increased bendability of the sheet without breaking or fracturing thereof.
Scoring allows the inf rg~ ly filled sheet to fold or bend along a smgle line up to about 180 from horizontal without fracturing the structural material. When multiple scores are made in a sheet on both sides thereof, the sheet can be bent up to 360 by being bendable in half in both directions. Before the present mvention, it was not possible to fold or bend inorganic sheet materials along a single Ime greater than about 10.
A preferred method of mahing a hinge having an , 'ly filled structural matrix within the scope of the present invention includes the steps of (1) mixing together water, an aggregate material, a water-dispersable organic polymer binder, and a fibrous material in order to form a moldable mixture; (2) forming the moldable mixture into a form stable sheet having an ~ 'ly filled structural matrix of a ~
thickness; and (3) scoring the sheet to form a hinge in the .~ "y filled structural matrix.
In general, the particular qualities of any ~...I,o, " of the present invention can be designed beforehand using a materials science and llUUIUa~ .' f ~
S approæh in order to give the v~L u. Lu.~ of the ;~ ly filled structural matrix the desired properties, while at the same time remauling cogtuz~nt of the costs and other involved in large scale .. .~ systems. This materials science and luil Iu~Llu~,~ul~ approach, instead of the traditional triai-and-error, mix-amd-test approach, allows for the design of ... ,,, .:. ,~lly filled materiaiS with the desired WO 95/21056 æ l 7 9 2 7 2 r~
':, , .

properties of high tensile and flexural strength, low weight, low cost, and low environ-mental impact.
The inrrgJPnirslly filled materials utilized herein do not require the use of .,llv;lu~ lly damaging methods or resources in order to supply the necessary rawmaterials. Fula~lllulci~ these materials are more ~,~lv;lul~ ~lly neutral, do not use ~llvilul.. l~li~lly harmful chemicals in their ~ fS~ , and do not create unsightly garbage which does not or very slowly degrades.
One aspect of the present invention is the novel hinge apparatus made of an II,y filled structural matrix that is bendable. Another aspect of the invention is a method of making the above hinge. A further aspect of &e invention are products 1~ containing the above hinge.
~R~ DES(~RIPTION OF TTTF. DRAWINGS
In order that the manner in which the above-recited and other advantages of the invention are obtained, a more pa~ticular description of the invention briefly described above will be rendered by reference to specific .. I.o.l- .. -t` thereof illustrated in the appended drawings. T ~ ' ' v that these drawings depict only typical ~ o.l;.. '~
of the invention and are not therefore to be considered hmitinQv of its scope, the invention will be described and explairled with additional specificity and detail through the use of the a~,~,Ul..~ i..g drav~ings in which:
Figures lA-I C include cross section side elevation views of inr~r~7 ~;rslly filled sheets with different shaped single scores;
Figures 2A-2C include cross section side elevaûon views of ~, 'Iy filled sheets with different shaped double scores;
Figures 3A-3G include cross section side elevation views of v '1~ filled sheets with different shaped multiple scores;
Figures 4A and 4B include cross section side views of in~rgæ~irslly filled sheets that have been bent along single and multiple score lines;
Figure 5 is a perspective view of a sheet bemg score cut by a knife blade cutter;
Figure 6 is a perspective view of a sheet bemg score cut by a continuous die cutroller;
Figure 7 is a perspective view of a score bemg pressed into a sheet by a scoringdie;
Figure 8 is a perspective view of a sheet being perforated by a perforation cutter;

-~ wo 95/21056 2 1 7 9 2 7 2 Figure 9 is a perspective view showing how a sheet with a score cut more easily bends at the score cut;
Figure 10 is a side view of a clamshell containe} showing the hinge of the invention;
Figure 11 is a rear view of the container shown in Figure 10;
Figure 12 is a top plan view of the container shown in Figure 10 in an open position;
Figure 13 is a schematic diagram of a method of making ;.. ~ ;ily filled products that can use the hinge of the invention;
Figure 14 is a Cu~ h'~ , perspective view of a system used to r ' C
an innrg~rlirolly filled sheet;
Figure 15 is an enlarged y.,l~ Livt~ view with cutaway of an auger extruder used in the system shown in Figure 14.
DF.T~ F~n DT~`~CRIPTION OF TF~, INVF NTION
The present invention is an apparatus comprising a hinge formed of a highly y filled composite matrix (referred to herein as " " ~ly filled" matrix or material). rl`he ;..-- ~ lly filled matrix comprises a water-dispersable organic polymer binder, an aggregate material, and a fibrous material. The hinge of the invention is utilized in sheets and containers .. r ~ from ;.. ~ ly filled materials that are generally lightweight and have a high strength to bullc density ratio. rl`he sheets and containers utilizing the hinge of the invention can be made to have a variety of densities and physical ~ I - ~- r- ~ ~ ;`l ;~ ` Specific properties or qualities desired for any product can be engineereci by proper selection of the material: -, and ~A----.r~
processes as taught herein.
o I. ~.T~`.T~R~,T, DT~CUSSION OF M~.TT~'RT~.T,~ -The innrgvo~;rlly filled materials and hinges made therefrom can generally be described as multi-~~ . t, multi-scale, fiber-reinforced, micro-~nn~ncit~c By carefully ;.. l.. rl; l~ a variety of different materials (including inorgarlics and fibers) capable of imparting discrete yet Yyll~ i~ly related properties, it is possible to create a unique class or range of micro-~ , having ~ ~lc properties of strength, toughnçss, ~v; - ' soundness, mass-~,ludu.,;l,;lily, and low cost.
The term "multi-cullll,vll.,lll" refers to the fact that the innr~niro11y filledmaterials used to make the sheets and hinges of the present invention typically include 2~7 g2~ 2 18 three or more chemically or physically distinct materials or phases, such as fibrous materials, inorganic aggregate materials, organic aggregate materials, orgar~ic polymer binders, rheology-modifying materials, hydraulically settable materials, water, other liquids, entrapped gases, or voids. Each of these broad categories of materials impOEts one or more unique properties to the final product made therefrom (as well as the mixture used to form the sheet). Within these broad categories it is possible to further include different r ' (such as two or more morganic aggregate pOEticles or fibers) whichcan impOEt different, yet ~ y properties to the sheets and hinges. This allows for the specific ~ of desired properties within the sheets and hinges in cu~.;. with the r ' ' ,, process.
The term "multi-scale" refers to fact that the ~ and materials of the present invention OEe definable at different levels or scales. Specifically, within the ;---..y~: -lly filled materials of the present invention there is typically a macro-component ~ in the range from about 10 . -- ...-- ~ to as high as about 10 mm, a micro-component c..."l,..-:'..,.. in the range of about I micron to about 100 microns, OEnd a submicron - - r ' Although these levels may not be fractal, they are usually very SimilOE to each other, and ~.. ~,. . - OEnd uniform within each level.
The term "fiber-reinforced" is self:,' y, although the key telm is which cleOEly ~ ;- .v., ~ the highly ~ _ "y filled materials of the present invention from Cu~ paper or paper products. cu..~ Liu~lal paper relies on "web" physics, or 1~ of fibers, to provide the rtructural matrix and mass, aswell as the binding, of the paper. However, the matrix of the , 'Iy filled materials used in the present invention relies on the bond or interaction between the organic polymer binder, fibers and/or other aggregates. The fibers act primOEily as a reinforcing component to ~ y add tensile strength and flexibility.
Besides the inclusion of much higher ~ ;h ~ of inorganic aggregate fillers, ~he present invention differs from CUII.. '' ' paper . ~ r ~ processes in a number of ways. First, far less water is used in the moldable mixtures (less than about 50% by volume) ofthe present invention compOEed to . U~ lLiu~l paper slurries, which typically contain water in an OEmount of at least 97% by volume, and even as much as 99.9% water. More i~ u~L.~Lly, the inn~nirslly filled sheets OEe formed from a highly cohesive, yet moldable mixture rather than an aqueous slurry ruch that once placed into a shape the inhrgsnirslly filled material will generally maintain its shape unless further acted upon. Moreover, the molclable mixtures will not shrink more thOEn about 10%, and 21~9272 WO 95/21056 r~-" ~ r~

not at all in some cases. Paper slurries, on the other h~md, will shrink by am amount of 60% or more during the paper-making process.
Finally,theterm"micro-composite"referstothefætthattheinnr~pnirsllyfilled materials are not merely a compound or mixture but a designed matrix of specific, discrete materials on a micro-level, which are of different sizes, shapes, and chemical make-up. The materials are ~ulr~ .;ly well bound and interactive so that the unique properties of eæh are fillly evidenced in the final composite (e.g., the tensile strength of the matrix has a direct correlation to the tensile strength of the fibrous ~ theinsulation of the matrix has a direct correlation to the total porosity amd insulative charæter of the aggregate material, etc.).
In light of these definitions amd principles, materials that include an organic polymer binder, fibers (both organic amd inorg;~nic), and inorganic aggregates can be combmed and molded into a variety of products. The highly ~ 'ly filled sheets that use the hinges of the present invention can substitute for sheets made from plastic, polystyrene, and even metal. The sheets can be cut and formed (such as by rolling or folding) mto a variety of containers and other articles of r ' The amd methods (includmg sheets made therefrom) are ~uL;~.ul~ly useful in the mass production of disposable container . and packaging, such as for the fast food industry.
Despite the differences in their c.. 1~ and r ' G7 the highly in.-lrc~ slly filled sheets _nd hinges of the present invention c~m be made to have the strength, toughness, flexibility, folding endurance, b.,~lddlJ;li~y, and look and feel of ordinary paper. Fl ' G7 the .. ~ . h r~ approach to designing the moldable mixtures used to make the ,, 'ly filled sheets allows for the " . ", r . h . . G of sheets having an extremely wide variety of properties not found in paper.
A. M~
~he highly ~ filled sheets that use the hinges of the present mvention havebeendevelopedfrvmtheperspectiveof~i-lv~L u-,lu~ ginordertobuild into the Ul;. IV .LIU~UIC of the highly in-lrg,s..;rslly filled material cerLain desired, ' prvperties7 while at the same time remaining cogruzant of costs and other . .. r . h.......... ;~ F~i~,~.ll.v,c, this Ill;~,lV:lLIU,LU~ ''L; ' ;"L analysis approæh, in contrast to the traditional i ' . ~ v., mix-and-test approach, has resulted in the ability to design highly; - ~ ly filled materials with those properties of strength, weight, insulation, cost, and ~ ;lvluu~ L~l neutrality that are necessary for ~I~Yl~ r sheetS and containers that use the hinge of the invention.

wo 95/21056 2 1 7 9 2 7 2 P~ s/o~ ~

The number of different raw materiaZs available to engineer a specifZc product is enormous, with estimates ranging from between fifty thousand and eighty thousand.
nZey c~Zn be drawn from such disparately broad cl~Zsses as metals, polymers, elastomers, ceramics, glasses, cnmrne;t-c and cements. Within a given class, there is some c.. ~;ly in properties, processing, and use-patterns. Ceramics, for inst~Znce, have l 0 a high moduius of elasticity, while polymers have a low modulus; metals can be shaped by dg and forging, while composites require lay-up or special molding techniques;
~ haulil,ully settable materiais, including those made from hydraulic cements hi.torically have low fZexuraZ strength, while elastomers have high flexuraZ stZength and elongation before rupture.
However,c.. ,~l.A.I,,.. lt.l;,~t;.,,,ofmateriaipropertieshasitsdangers;itcEtnlead to ~ rl ;nl I (the m--t~ rgict who kno~s nothing of ceramics) and to CO~ vaLive thinking ("we use steel because that is what we have always IZsed''~. It is this - and -,u~ ,. v~iivc thinking that has iimited the ~ ;". . of using highly innr~P~ lly filled materials for a variety of products, such as Zn the Illau~lf~lb.c of paper-like sheets.
1.. ~;,.. -.11~ filled materiais have a wide utility and can be designed and lllh lui~hucLIuaZly engi~neered for use in a variety of products. T"...,,~ y filled materiais have an advantage ovcr other ~UII~ iUll~d materia~Zs in that " "~, fii'Zed mâterials gain their properties under relatively gentle and l~ conditions.
(Other materiais require high energy, severe heat, or harsh chemicaZ processing that SiZs~ur~ lyaffectsthemateriaZ ~ ) Moreover,cerlainCull~. 'materiais, or ~ thereof, cEtn be , ' into the ilighZy in~Zrgær ;r~lly flled materiaZs used in the present invention with surprising synergistic properties or results.The design of the, , used in the present invention has been developed and narrowed, first by prir~Zary constraints dictated by the design, and then by seeking the subset of materiaZs that maxirnizes the Z,, r of the ~""'l"' :~ At a'ZI times during the process, howevcr, it is important to reaiize the necessity of designing products that can be Ill~.~à~L~. cd in a Cost-cullll,~LiLivc process.
Primary constraints in materials selection are imposed by . l ~ of the design of a component which are criticaZ to a successfuZ product. With respect to a sheet used to make, for example, a food and beverage container, those primary constraints include minimaZ weight, strength (both CUIII~JIC:7:>;VC and tensile), and toughness require-ments, while ' 1~ keeping the cost ~ / to that of paper, plastic, and metal ~uu~ J~ub.

wo 95/21056 r~ J~
217~27~

As discussed above, one of the problems with materials having high .,. ,.. ~ . -1;. ,.. ~ of inorganic materials in the past has been that they are typically poured into a form, worked, and then allowed to set, harden, and cure over a long period of time --even days or weeks. Such time periods are certainly impractical for the economic mass production of disposable containers and similar products.
As a result, an impoltant feature of the present invention is that when the highly filled mixture is molded into a sheet~ it will maintain its shape (i~e~ support its own weight subject to minor forces, such as gravity and movement through theprocessing equipment) in the green state without eAYtemal support. Further, from a f~ ; I tg perspective, in order for production to be c ... ... :. _l it is important that the molded sheet rapidly (in a matter of minutes, or even seconds) achieve sufficient strengtb so that it can be handled using ordin~ry r ' ' g procedures, even though the highly ~ , filled mixture may still be in a green state and not fully hardened.
Another advantage of the ~ ua.~ and materials science approach used in the present invention is the ability to develop c,.",l.~,- ';" ~ in which cross-sections of the structural matrLY are more l ~ than have been typically achieved in the prior art. Ideally, when any two given samples of about 1-2 mm3 of the 'ly filled strucAtural matrix æ taken, they will have ,.,1.- ~ y similar amounts of voids, aggregate particles, fibers, any other additives, and properties of the matrix.
In its simplest form, the process of using materials science in ",: . "~l " .. ~ ly ..., ;.. ;"~ and designing an , ~ly filled material comprises ~ , ;,;"p analyzing, and modifymg (if necessary): (a) the 1~ , (b) tbe predicted particle packing, (c) the system rheology, (d) the average fiber length and packing density, and (e) the processing and energy of the A ' ' ~ system In . 1 _. ~.;; .~. the ,,~ ~ the average particle si~e is ~' 1, the natural packing density of the particles (which is a function of the shape of the particles) is~l~t. rA:lr~1,andthestrengthoftheparticlesis ' ' ' Withthis;,.C~..,.- ;,...,the particle packing can be predicted according to, -:1 ~ models. It has been ~c~s~hljeh~cl that the particle packing is a primary factor for designing desired ~ci, of the ultimate product, such as workability, form stability, shrinkage, bulk density, insulative r~r-hiliti~-e tensile, CullllJlu~:~'t~., and flexural strengths, elasticity, durability, and cost ~"; ~ 11 The particle packing is affected not only by the particle and aggregate ~ ;- but also by the amount of water and its l ~ , to the inteFatitial vûid vûlume ûf the packed ~

W0 95/21056 2, 1 ~ ~ 2 7 Z ' r~ a~51a ~ . ~
~2 System rheology is a function of both macro-rheology and micro-rheology. The maero-rheology is the l~,la~iullaLIIJ of the solid particles with respeet to eaeh other as def;ned by the partiele packing. A;he miero-rheology is a funetion of the lubrieant fraetion of the system. By, ., .~. l; r. . .A; I I . . of the lubrieants (whieh may be water, the water-dispersable binder, r~ tjrj7"rS, ~iiCr~ ltC, or other materials), the viseosity and yield stress eAn be ehemieally modified. The miero-rheology can also be modified physically by changmg the shape and size of the particles: e.g., chopped fibers, plate-like miea, round-shaped silica fume, or hydraulically settable binder particles will interaet with the lubrieants differently.
Finally, the ,., --, r I ~ g process can be modified to manipulate the balance between workability and form stability. As applied to the present mvention, this beeomes important in s4 .~ ily increasing the yield stress during formation of the sheet by either chemical additives (such as by adding a particular water-dispersable binder) or by adding energy to the system (such as by heating the molds). Indeed, it is this discovery of how to manipulate the ;..~ ..~;,- .:. Ally filled ~ ~ ~ r- - m order to quickly increase the fomm stability ofthe ~ during the fommation process that make the present mvention such a sigluficant ~1~ in the art.
From the following diseuQsion, it will be appreciated how eaeh of the component materials within the ~ lly filled mixture, as well as the processing p^~ t~rc contributes to the primary design eonstraints of the partieular sheet and hinge to be r ~"150 that they can be ~ ly mass produced. Specific c~
are set forth in the examples given later in order to ~ --- how the, - - ; ., ,: ,-l ;, .. .
of the l~ r.... ~ of eaeh component , ' ' the ~ ~l - - ' ;.~.~ of desired proper-ties.
B. r~ r~
The terms " v "~/ filled mixture" or "moldable mixture" have ;. .t. . . I . . . ~ meal~ingS and shall refer to a mix~ure that can be molded into the sheets and hinges that are disclosed and elaimed herein. Sueh mixtures are ~ l by having a bigh c...,~ . of inorganie filler or aggregate (at least about 40% by volume of the total solids eontent of the dried sheet), water, a water-dispersable binder, and a fibrous material. The mixtures may also inelude other admixtures sueh as rlqctiri7 -Q lubrieqnts, rlicr~ cqntQ~, hydraulieally settable binders, and air void forming agents, which will be discussed in further detail below.

wo 95/21056 ~ 7 2 ~1/. ot .

S Moldable mixtures are ~ ;1 as having a relatively high yield stress, which makes them highly workable and cohesive, yet form stable ~ or shortly after being molded into the desired shape. The terms ";.. ~ ly filled mixture", ";. ,... ~. -lly filled moldable mixture", or "moldable mixture" shall refer to the mixture - regardless of the extent of drymg or curing that has taken place. Such mixtures shall include mixtures tbat are highly workable, which are partially dried, and which have been completely dried (although a certain amount of water will usually remain within the sheets as bound water within the water-dispersable birlder).
After the moldable mixture has been formed into the desired shape, the resultingsheet or object made therefrom will have a "highly filled - ~ ~Ul~ polymer 15 matrix"," ~ "~filledmatrix",or";.. ~ llyfilled,organicpolymermatrix".
These temls shall refer to such matrices regardless of the extent of drying or curing that has taken place, the only limitation being that the sheet or object made therefrom is form stable. ~v~l...~., a highly filled imorganic matrix can refer to a fresh sheet or object made therefrom as well as a sheet or object that ha been partially or totally dried.
Both the moldable mixture and the innrg7~ir~11y filled matrix formed therefrom each constitute "highly ~, - 'Iy filled materials" or "highly ;.. ~ ly filled çn~rneit~e " As before, these terms shall refer to materials or composiks without regard to the extent of wetting, setting, drying, or hardening that has taken place. They shall include materials and composites in a green (ie., ~ ,1) state, as well as semi-dry or hardened materials after they have been molded mto sheets, hinges, containers, or other objects.
c w n- c r-Th~ Ol~d~ mixturesusedto.., r~ thehighly;.".~ 1Iyfilledsheets and hinges of the present invention develop strength properties through the drying out of a ~ ,.I'y solvated water dispersable organic binder. The moldable mixtures firstdevelop workability and flow properties by adding am amoumt of water to the mixture sufficient to lubricate the solid inorganic aggregate particles and fibers, amd to solvate, or at least disperse, the wakr-dispersable organic binder. Thereafter, the removal of water, such as by ~v~ uldliull~ allows the water-dispersable binder to develop its maximum strength prop~rties.
For example, certain starch-based makrials can be purchased as tmy granules which are in a powder-like form. The starch based binder is "activated" by dissolving and gelating the starch binder in wate} by heating the dispersion abûve the gelation wo ss/210s6 21 7 ~ 2 7 2 r~
i 24 t.llll,.. alulc. After the water has been removed, such starch based materials can, by themselves, have tensile strengths of up to about 40-50 Mpa. Through careful ILIL~.Iuauu~,luLal ~ the highly i ,, ~ filled sheets (and containers or other objects made therefrom) can have varying tensile strengths, even a,u~ 40 Mpa in some cases.
The water-dispersable organic binder not only binds the individual aggregate particles and fibers together within the mixture upon drying or hardening (thereby forming a structural or highly innrg,s~irslly filled matrix), but also has the general tendency of affectrAg the rheology of the moldable mixture. In fact, the water-dispersable brnders disclosed herein have been used in ..,....:;l;.. ~ and other lly~L~ allJ settable mixtures as rheology-modifying agents, although it has been understood that they also impart a degree of binding to the final hardened material if included in large enough amounts.
The various water-dispersable organic binders ~ .' ' by the present invention can be roughly orgaluzed into the following categories~ aa~ l~;d~ and derivatives thereof, (2) proteins and derivatives thereof, and (3) synthetic or~aric materials. E~blyarw~ ;lc rheology-modifying agents can be further subdivided ir to (a) cellulose-based materials and derivatives thereof, (b) starch-based materials and derivatives thereof, and (c) other ~ol~ a ~ The various organic binders can be used separately or m a variety of mixtures.
Suitable ~llulu.. ~ -haacd polymer bmders include, for example, 1ll. ~11l, l~u~y-ethylcellulose, l~l~u~.ylll.ll~l-;L~lccllulose, ua~bu~lu~ cllulose, ' ~
C~ ' , IIJ~ILU~ " ' , hyl~w~ lpluuy- ~ ' , etc. The entire rânge of possible L ' " is enormous and shall not be listed here, but other cellulose materials that have the same or similar properties as these would also work well. Some cellulose-based binders can also be cross-pol~lll. .~.l in solution; an example of this is Cellosize~lD, a L~l~u~ ~ ' " ' product available from Union Carbide. Cellosize i9 can be cross-linked in water with r' '' ' ~ , methylol ureas, or melamine-.le resins, thereby forming a less water-soluble binder.
Suitable starch-based polymer binders include, for example, aLIl~lu~
amylose, seagel, starch acetates, starch l~ u~ l ethers, ionic starches, long-chain dlkyla~au,h~ ~, dextrins, amirle starches, phosphate starches, dialdehyde starches, etc.
Other natural pol.~aacclLaL;~-based binders mclude, for example, alginic acid, phycocolloids, agar, gum arabic, guar gum, locust bean gum, gum karaya, and gum tragacanth.

wo 951~1056 J _I/~J.~,_.( 7 2~ 7~272 Suitable protein-based binders include, for example, Zein0 (a prolamine derived from com), collagen (derivatives extracted from animal connective tissue such as gelatin - and glue), and casein (the principle protein in cow's milk).
Finally, suitable synthetic organic polymer binders that are water dispersable include, for example, polyvinyl ~ ulidullc~ pol~ ; glycol, polyvinyl alcohol, ~ul~ ~h-rl.ll., h~l ether, polyacrylic acids, ~Ol~a~lyli~ acid salts, ~uly V;ll,y la~ , acids, pOly~ la~,lylh, acid salts, pOl~a.,ly' ' ethylene oxide polymers, polylactic acid, synthetic clay, and latex (which is a broad category that includes a variety of PUIJI.~ substarlces formed in a water emulsion; an example is styrene-butadiene cu~ul~ll~.,~).
The water-dispersable organic binders within the moldable mixtures used irl the present invention are preferably included in an amount such that an in~ ni~ally filled structural matrix made therefrom will contain from about 1% to about 50% organicbinder by volume of the total solids within the structural matrix, more preferably from about 2% to about 30% by volume, and most preferably from about 5% to about 20% by volume.
D. A
Inorganic materials commonly used in the paper industry, as well as more finely ground aggregate materials used in the concrete industry, may be used in the moldable mixtures of the present invention. N~ ,.al~ " the size of the aggregate or inorganic filler materials will often be many times larger than morganic filler materials used in the paper industry. While the average diameter of the particles within the inorganic fillers used in the paper industry will usually be less than 2 microns, the average particle diarneter of the aggregat~ materials used in the present invention can, m some cases, be up to 100 microns or larger depending on the wall thickness of the resulting sheet and, hence, can be less expensive.
The inorganic filler materials used in the paper indus~y are required to be muchsmaller and are generally more uniformly sized than the aggregate particles used in the moldable mixtures of the present invention. In fact, it is often preferable to use a wide range of particle sizes in the present invention in order to increase the particle-packing density of the moldable mixture. Unifommly sized particles typically have a packing density of about 0.624. The result is that the inorganic materials used in the present invention will generally cost far less than the inorganic filler materials used m the paper industry.

wo ssnlos6 ~1~ 9 2 7 2 It is far more expensive to maintain the extremely small particle size tolerances required in the paper industry, as well as ~ - e a general uniformity of particle size The greatly increased range of particle sizes also allows for a much larger variety of inorganic aggregate materials to be used in the present invention compared to the ", . ,..r . l c of paper.
The aggregates used in the present invention do have size limitations imposed by the generally ~ " ' structures that utilize the hinge of the invention The diameter of the aggregates used will most often be less than about 25% of the smallest cross-section of the structural matrix forming the hinge Because of the much larger variety of aggregate materials that may be added to the moldable mixtures in the present invention compared to the inorganic fillers used to c paper, the aggregate materials of the present invention may be selected to impart a much larger ~ariety of properties to the fnal sheet. Whereas in paper, the inorganic filler is added mainly to affect the color and the surface quality of the resulting sheet of paper, the aggregate materials employed in the present invention can be added to increase the strength (tensile and, especially, CUIIAIJIC~ strength), increase the modulus of elasticity and elongation, decrease the cost by acting as an i.,~ filler, decrease the weight, and/or increase the insulation ability of the resultant highly innre;s~ni~slly filled material.
Examples of useful ~ ~ ,, which can be used singly or in a variety of mixtures, include perlite, ~. ' sand, gravel, rock, limestone, sandstone, glass beads, aerogels, xerogels, seagel, mica, clay, synthetic clay, alumina, silica, fly ash, fumed silica, fused silica, tabular alumina, kaolin, III;~IU~ C~ hollow glass spheres, porous ceramic spheres, gypsum such as gypsum &ydrate, calcium carbonate, calcium aluminate, xonotlite (a crystallme calcium silicate gd), lightweight expanded geologic materials such as lightweight expanded clays, hydrated or unhydrated hydraulic cement particles and other ll.yL~ l;cally settable materials, pumice, exfoliated rock, and other geûlogic materials. Partially hydrated and hydrated cement, as well as silica fume, have a high surface area and give excellent benefits such as high initial coLc;,;~ of the freshly formed sheet.
Plate-like aggregates, such as mica and kaolm, can be used in ûrder to create a smooth surface finish in the innrgsn;~ ~11y filled material. Typically, larger aggregates, such as.calcium carbonate, give a matte surface, while smaller particles give a glass surface. The advantage of the present invention over the Ill~i~c of conventionalpaper is that any of these aggregate materials may be added directly into the matrix.

~ WO95121OS6 ~732~2 - r .,.
Even discarded ~ y filled materials, such as discarded sheets, containers, or oLher objects c~m be employed as aggregate fillers amd ~L~ It will also be appreciated that the sheets and _inges of the present invention can be easily arld effectively recycled by simply adding them to fresh moldable mixtures as anaggregate filler.
Clay and gypsum are particuLrly important aggregate materials because of their ready availability, extreme low cost, wulLabil;Ly~ ease of formation, and because they can also provide a degree of binding and strength if added in high enough amoumts. "Clay"
is a term tbat refers to materials fourld in the earth that bave certain chemical and properties. The IJIC ~ ' ' clays mclude silica and alumina (used for makirlg pottery, tiles, brick, and pipes) and kaolinite. The kaolinitic clays are anauxite, which has the chemical formula Al2O3-3SiO2-2H2O, and, . l . ., ;l .,, which has the chemical formula Al203-4SiO2-H20. Clays may also contain a wide variety of other5llh.t9ArPC such as iron oxide, titarlium oxide, calcium oxide, zirconium oxide, and pyrite.
Althougb clays can obtsAin hardness everl without being fired, sh urlfired clays are vulnerable to water ~ . and exposure, are extremely brittle, and have low strength. N..."lh~,L,~" clay makes a good, i,l~A,u~.~;ve aggregate within the " 'Iy filled ~ , of the present invention.
The aggregate material used m the present invention can include a 1./ Laul;~lly settable material such as calcium oxide, gypsum l~ .' hydraulic cements, or various mixtures thereo Gypsum I ' ~.' is hydratable and forms the dihydrate of calcium sulfate in the presence of water. Thus, gypsum may eAhibit the l A ~ of both an aggregate and a brnder depending on whether the 1 - ~,' or dihydrate form is added to a moldable mixture, and the: thereo Various hydraulic cements can be added as an inorganic filler material within the moldable mixtures of the present invention. Not only are hydraulic cements relatively ill~.Al)~ ;V~ amd plentifill, but they also can impart a degree of binding to the ; ...., ~; ~lly filled matrix if included in high enough amoumts. In addition, hydraulic ~5 cement chemically reacts with water, thereby causing an mternal drying effect within the moldable mixture which effectively removes at least some of the water within the- mrxture without the need for ~.~Uul~Liu.l. The same is true for gypsum 1l~,.. ~.~.' and calcium oxide. ~c~,' ' cement particles may also be added as am aggregate filler.

wo 9s~2~05~ ~ 1 7 9 2 7 2 One difference between unhydrated and IJ~cl~yl' ' cement is that the latter has a distinctly different . ' ~ Y, including microgel and platelets.
The terms "hydraulic cement" or "cement" as used herein are intended to include clinker and crushed, ground, milled, and processed clinker in various stages of '~ aliu.. and in various particle sizes. Examples of typical hydraulic cements that can be utilized singly or in various mrstures include: the broad family of portland cements such as portland grey cement and portland white cement (including ordinary portland cement without gypsum), MDF cement, DSP cement, Densit-type cements, Pyrament-type cements, calcium aluminate cements (including calcium aluminate cements without set regulators), plasters, silicate cements (including B-dicalcium silicates, tricalcium silicates, and rnixtures thereof), gypsum cements, phosphate cements, high alumina cements, microfine cements, slag cements"" .~ ,.., u~,Llu cements, and aggregates coated with microfine cement particles.
In addition, the hydraulic cement can effect the rheology of the moldable mixture, at least in part by chemically reacting with the water, thereby ~ the amount of water available to lubricate the aggregate particles and fibers. In addition, it has been found that portland grey cement increases the intemal cohesion of the moldable mixture, perhaps because of the increase in amount of aluminates within this type of cement. Finally, although the ' is not clear, it appears that hydraulic cement may interact to some degree with the large number of hydroxyl groups present on many orgarlic polymer binders. The hydroxyl groups of such binders will, at a minimurn, have hydrogen I ' ~ int~ntinnc with the highly polar hydraulic cement gel products, being known to adsorb onto the surface of cement particles.
Because of the nature of the moldable mixtures and sheets made therefrom, it is possible to include lightweight aggregates having a high amount of interstitial space in order to impart an insulation effect with the molded sheets. Examples of aggregates which can add a lightweight ~ to the moldable mixture include perlite, ~. : " glass beads, hollow glass spheres, synthetic materials (e.g, porous ceramic spheres, tabular alumina, etc.), cork, lightweight expanded clays, lightweight polymers, sand, gravel, rock, limestone, sandstone, pumice, and other geological materials.
In addition to CU~ ILiUI~I aggregates used in the paper and cement industries, a wide variety of other aggregates, including fillers, ~ r~ ~ih ~ ~, including metals and metal alloys (such as stainless steel, calcium aluminate, iron, copper, silver, and gold), balls or hollow spherical materials (such as glass, polymeric, and metals), filings, pellets, powders (such as microsilica), and fiber aggregates (such as graphite, sllica, alumina, .

~ wo gsmos6 2 ~. ~ 9 2 7 2 r S fiberglass, polymeric, organic fibers, and other such fibers typically used to prepare various types of composites), may be added to the moldable mixtures within the scope of the present mvention. The fiber aggregates are to be .1~ from the fibrous material discussed in detail below. Even materials such as cork, seeds, starches, gelatins, and agar-type materials can be I ' as ~ ." Although these latter aggregates are organic (and readily l~ L~ A~ ), they are included here because they act primarily as a filler not a binder. Any of the above aggregates can be added simgly or in a variety of mixtures.
Another class of aggregates that may be added to the ;~ L ~ Ally filled mixture includes inorganic gels amd microgels such as silica gel, calcium silicate gel, aluminum silicate gel, and the like, which may be added singly or in a variety of mixtures. These can be added in solid form as any ordinary aggregate material might, or they may be I in situ. Because they tend to absorb water, they can be added to reduce the water content (which will increase the yield stress) of the moldable mixture.
In addition, the highly ;~r~;lU;~U~;C nature of silica-based gels and microgels allows them to be used as moisture regulation agents within the final hardened sheet. By absorbing moisture from the air, the gels and microgels will cause the ~ 'ly filled sheets to retain a ~ ;iJ ~ amoumt of moisture umder normal ambient conditions.
(Of course, the rate of moisture absorption from the air will correlate with the relative humidity of the air). Controlling the moisture content of the sheets allows for more careful control of the elongation, modulus of elasticity, bendability, foldability, flexibility, and ductility of the sheets.
It is also within the scope of the present invention to include pul~
inorganic aggregate materials, such as pol~ll.~ li~l,l~ silicates, within the moldable mixture. These may be added to the mixLure as ordinary silica or silicates, which are then 30 treated to cause a pol~ .i~iiu.. reaction in situ in order to create the pol.~ll.~li~l silicate aggregate. rulylll~i~l imorganic aggregates are oflen ad~ , in certain ~j,~.l;. .~;...,~ because of their increased flexibility compared to most other inorganic aggregate materials.
It is oflen preferable, according to the present invention, to include a plurality

3~ of differently sized and graded aggregates capable of more completely filling the interstices between the aggregate particles and fibers within the moldable mixture.
Optimizing the particle packing density reduces the amount of water that is required to obtain the desired level of Wu~ ;liLy by ~l; ; Af; ~ spaces that would otherwise be filled ~Lt~L interstihal water, ûften r~ferred tû as "capillary water."

WO 95/~10S6 P~ . S
~9272 ;

In order to optimize the packing density, differently sized aggregates with particle sizes ranging from as small as about 0.05 microns to as large as about 2 mm may be used. (Of course, the desired purpose and thickness of the resulting product will dictate the appropriate particle sizes of the various aggregates to be used.) It is within the skill of one in the art to know generally the identity and sizes of the aggregates to be used in order to achieve the desired rheologicai properties of the green moldable mixtures, as well as the fmai strength and weight properties of the final hardened innrgpni~lly filled composite.
In certain preferred . ., I..,.il.,. ,~ ofthe present invention, it may be desirable to maximize the amount of the aggregates within the moldable mixture in order to15 maximize the properties and . l. - ,.. ~. . ;~l ;. ~ of the aggregates (such as qualities of strength, low density, or high insulation). The use of particle packing techniques may be employed within the highly ~ ly filled material im order to maximize the amount of such aggregates. The particle packing density of the aggregate material used in the innre~nir5~1y filled matrix is at least about 0.65, preferably at least about 0.75, and most preferably at least about 0.85.
A detailed discussion of particle packing can be found in the following article coauthored by one of the inventors of the present invention: Johansen, V. &~ Andersen, PJ., "Particle Packing and Concrete Propcrties," ~ ' ' SriPnr~ of t'nnrrete II at 111-147, The American Ceramic Society (1991). Further i r ' is available in the Doctoral Dissertation of Anderson, P.J., "Control and Monitoring of Concrete Production -- A Study of Particle Packing and Rheology," The Danish Academy of Technical Sciences. For purposes of disclosure, the foregoing article and doctorai d;~ Liùl~ are iU~,Ul,UI ' ' herein by specific reference. In ~ I " in which it is desirable toobtain a sheet (or object made therefrom) having a reduced density and a high insulation capability, it may be preferable to incorporate into the highly ;.. ,. ~,, .: -lly filled matrix a lightweight aggregate that has a low thermal Cu~l~u~Liv;Ly, or "k-factor" (def;ned as W/m-K). The k-factor is roughly the reciprocai of the expression commonly used im the United States to describe the overall thermal resistance of a given material, or "R-factor,"
which is generally defined as having units of hr-ft2FlBTU. The term R-factor is most commonly used in the United States to describe the overall thermal resistance of a given material without regard to the thickness of the material. However, for purposes of ...- .~ ;~.... it is common to normalize the R-factor to describe thermal resistance per imch of thickness of the material in question or hr ft2F/BTU-in.
.

~ wo gsl2l0s6 ~ 1 ~ 9 2 7 2 r~
S For purposes of this `l '` ~ ~1;......... the msulation ability of a given material will hereinafter be expressed only in terms of the IUPAC method of describing thermal~,ulld.l.iiviLy, i.e., "k-factor." (l~e conversion oftbermal resistance expressed in British units ~rft2~F/BTU-in) to IUPAC units can be performed by lllulL;~ illg the normalized number by 6.9335 and then taking the reciprocal of the product.) Generally, aggregates having a very low k-factor also contain large amoumts of trapped interstitial space, air, mixtures of gases, or a partial vacuum which also tends to greatly reduce the strength of such aggregates. Therefore, concerns for insulation and strength tend to compete amd should be carefully balanced when desiglung a particular mixed design.
The preferr~d insulating, lightweight aggregates mclude expanded or exfoliated 1~ vermiculite, perlite, calcined .i . .. ,.. ~ eard, and hollow glass spheres - all of which tend to contain large amounts of ill~ ul~)~ ' interstitial space. However, this list is in no way intended to be exhaustive, these aggregates being chosen because of their low cost amd ready availability. N~..lll.l~..~, any aggregate with a low k-factor, which is able to impa~t suf~icient insulation properties to the sheet or other article made therefrom, is within the scope of the present invention.
In light of the foregoing, the amount of aggregate that will be added to the moldable mixture used in forming am in- rgs~i~slly filled structural matrix will depend on a variny of factors, mcluding the qu~mtity and identity of the other added r ' ~
as well as the particle packing density of the aggregates thernselves. Tne inorgarlic aggregate ~ , used m the present invention will preferably be included in an amount from as low as about 40% by volume of the total solids content of the "~, filled structural matrix to as high as about 98% by volume, more preferably in the range from about 50% to about 95% by volume, and most preferably in the range from about 60% to about 80% by volume of the total solids.
~0 As sn forth above, differently sized aggregate materials may be added in varying amounts in order to affect the particle-packing density of the moldable mixture.Depending upon the natural packing density of each aggregate material, as well as the relative sizes of the particles, it is possible that the resulting volume of the combined aggregates will be less tham the sum of the volumes of the aggregates before they were ~5 mixed.
E. Fibers As used in the ~ ; - . and the appended claims, ~e terms "fibers" or "fibrous materials" include bûth inorgatlic fibers and ûrganic fibers. Fibers may be added wo ssnlos6 ~ C, ~ , to the moldable mixture to increase the cohesion, elongation ability, deflection ability, toughness, fracture energv, and flexural, tensile, and on occasion cu...,u.cDD;ve strengths ofthe resulting i~ ;r~ lI.y filled material. Fibrous materials reduce the likelihood that the highly ~ , filled sheets, or articles made therefrom, will shatter when cross-sectional forces are applied.
In evaluating potential fibers for use in the inorganically filled material used in forming the hinge of the present invention, important . ~ to consider are: the physical properties of the fibers (e.g., length and diameter, tensile strength, and wetabililylli~l...~_l..lity), cost, reliability of supply (quantity and CUIID;D~I1~.Y), the relative level of, in the fiber (e.g.,lignin, pectin, fats/waxes, etc.) and the .rrrr~ ity of the fiber to food contact al~ The use of fibers dramatically increases the fracture energy of the material, which makes the containers and hinges formed therefrom IJr~Liculrll.y useful for packaging, storing, and shipping goods.
Examples of fibers that may be ufilized singly or in a variety of mixtures include glass fibers, silica fibers, ceramic fibers (such as alumina, silica nitride, silica carbide, graphite), rock wool, metal fibers, carbon fibers, and synthetic polymer fibers such as p~l.yulu~lcll~ , nylon, or rayon fibers. Fibers extracted from plant leaves and stems may be used, as well as any naturally occurring fiber comprised of cellulose.
Such fibers are available from wood and paper pulp (e.g., wood flour or saw dust~, wood fibers (both hard wood or soft wood, examples of which mclude sûuthern hardwood and southern pine, I~ LiV~ recycled paper, cottûn, cotton Imters, abaca (extracted from a Philippine hemp plant related to the banana), sisal, jute, sunn hemp, flax, amd bagasse.
Recycled paper fibers are somewhat less desirable because of the fiber rlr~ ;.... that occurs during the original paper ~ ~. process, as well as m the recycling process. The above fibers are used in the present invention due to their low cost, high 30 strength, and ready availability. N.. llllcl.,.. ~., amy equivalent fiber tbat imparts ~)IIIUIC DDIV~ and tensile strength, as well as toughness and flexibility (to the extent needed), is within the scope of the present invention. The only limiting criteria is that the fibers impart the desired properties without adversely reacting with the other ~ . ..t~
of the ;.. y,~ filled material and without ~ _ the materials (such as fûod) 3~ stored or dispensed in objects made from sheets containing such fibers.
Fibers that may be il.~ u.r l into the " 'Iy filled matrix preferably include naturally occurring organic fibers, such as cotton fibers, wood fibers? abaca fibers, and inorgarlic fibers made from glass, graphite, silica, ceramic, or metal materials.

wo 95121056 r 2~ 7~272 For purposes of illustration, abaca fibers are available from Isarog Inc. in the r ~ ., while glass fibers, such as Cemfill 19, are available from Pilkington Corp. in England.
- It should be understood that the fibers used within the scope of the present invention differ from fibers typically employed in making paper or cardboard sheets, primarily in the way in which the fibers are processed. In the .. ~ . of paper, either a Klaft or a sulphite process is typically used to fomm the pulp sheet. In the K~ft process, the pulp fibers are "cooked" in a NaOH process to break up the fibers. In a sulphite process, acid is used in the fiber ~' ~ process.
In both of these processes, the fibers are first processed in order to release lignins locked within the fiber walls. However, im order to release the ligrlins from the fiber, some of the strength of the fiber is lost. Because the sulfite process is even more severe, the strength of the paper made by a sulphite process will generally have only about 70%
of the strength of paper made by the Kraft process. (Hence, to the extent wood fibers are mcluded, those processes using a Kraft process are preferred.) The fibers used in making the sheets and hinges of the present invention preferably have a high length to width ratio (or "aspect ratio") because longer, narrower fibers can impart more strength to the ;...., ~ filled structural matrix withoutf~r~.,au~1y adding bulk and mass to the composite materials. The fibers should have anaverageaspectrstioofatleastaboutlO:l,preferablyatleastaboutlOO:l,andmost prefersbly at least about 1000:1. N.~..lh.l.,~, fibers having a smaller aspect ratio are generally more easily placed witbin the sheet and yield 8 sheet with more uniformity and fewer defects.
The amount of fibers added to the moldable mixture used m forming an ~ 'Iy filled structural matrix will vary depending upon the desired properties of the final product, with tensile strength, tougbness, flexibility, snd cost bemg the principle criteria for ~ ~ the amoumt of fiber to be added in any mix design. The - of fibers within the structmal matrix will preferably be in the r~mge from about 0.5% to about 50% by volume of the totsl solids content, more preferably from sbout 2% to about 30% by volume, and most preferably from about 5% to about 20% by volume. In light of these r~mges and those given with respect to the organic polymer binder, the total amount of organics within the structursl matrix will preferably be less than about 60% by volume of the total solids content, more prefersbly less than about 40% by volume, and most preferably less thsn about 30% by volume.
It has been foumd that slight mcreases of fiber ~ below about 20%
fiber by volume tend to ~ d~i~,ally increase the strength, toughness, dnd bending 21~ ~ 2 ~ ~ ; r ~

S endurance of a finished sheet. Adding fibers above about 20% by volume will produce a less dramatic increase in the strength and flexibility of the sheet, aithough such increases may be ec~n~ ly justified in some .,;1l -It will be ~ 1, however, that the strength of the fiber is a very important feature in ~ ~ the amoumt of the fiber to be used. The stronger the tensile strength of the fiber, the less the amount of fiber that must be used to obtain a given tensiie strength m the resuiting product. Of cou~se, while some fibers have a high tensile and tear and burst strength, other types of fibers with a lower tensile strength may be more elastic. Fibers with a smaller aspect ratio are more easily piaced and yield a sheet with fewer defects, while a larger aspect ratio increases the strength-imparting effect of the fiber. A ' of two or more fibers may be desirable in order to obtain a resuiting product that maximizes multiple ~ , such as higher tensile strength, higher elasticity, or better fiber placement.
It should aiso be understood tbat some fibers, such as southem pine and abaca, have high tear and burst strengths, while others, such as cotton, have lower strength but greater flexibility. In the case where better placement, higher flexibility, arld higher tear and burst strength are desired, a, ' ~ln of fibers havimg varying aspect ratios and strength properties can be added to the mixture. For example, a mixture of southem hardwood and southem pme ailows for better dispersion of the fibers throughout the moldable mixture, yielding a sheet with good fiber dispersion and excellent folding endurance. In any event, as set forth more fuily above, the fibers used m the present invention preferably do not undergo the intense processing of fibers used to maice paper.
Because of this, they maintain far more of their originai strength.
FiDally, it is i~nown that certain fibers amd inorganic filiers are able to chemicaily mteract amd bind with certain starch-based organic polymer binders, thereby adding another dimension to the materiais of the present imvention. For example, it is i~nown that many fibers and inorganic fillers are anionic im nature amd i~ave a negative charge.
Therefore, in order to maximiæ the interaction between the organic binder and the anionic fibers and morganic materiais, it may be ad. ,, to add a positively charged organic binder, such as a cationic starch Better water resistance can be obtained by treating the fibers with rosin and aium (Ak(SO4)3) or NaAl(SO4)2, the latter of which precipitate out the rosin onto the fiber surface maicing it highiy llr~ llub;. . The aiuminum floc that is fommed by the aium creates an anionic adsorption site on the fiber surface for a positively charged organic binder, such as a cationic starch.

~ wo gS/21056 3 r~
S Fibers are particuiarly important where a sheet has been scored and is expected to bend over a large angle (discussed in further detail beiow). Not oniy can fibers have a random orientation, but in addition, the properties imparted to the hardened sheets by the fibers can be increased by ~ ly or bidirectionaily orienting the fibers witbin the sheet. Depending on the silape of the extruder die head, the extrusion process itself will tend to orient the fibers in the "Y" (or l.".~jl.. l ~) direction. The sheet thiciiness reduction process, during which the sheet is aiso elongated, furtber orients the fibers in the "Y" direction.
In addition, by using a pair of rollers having different . .. ;~ in the "Z"
direction (or normai to the surface of the sheet), such as by using a fiat roller paired v~ith a cor~icai roller, a percentage of the fibers can be oriented im the "X" (or width-wise) direction. This is thought to occur because the conicai roller c~m widen the sheet in the "X" direction. In this way a sheet havmg ' " ~liulldlly oriented fibers can be manufac-tured. As a resuit, the desired strength ~ can be engineered into the resuitant sheet.
The fibrous materiai can aiso be disposed in an; ~ æ~ filled matnx so that the individuai fibers have a substantiaily higher level of directionai orientation at or near the surface of the ~ "~/ filled matrix compared to fibers within the imterior of the jnrr~;lrlir~lly filled matrix.
2~ F. Water Water is added to the moldable mixture in order to solvate, or at least disperse, the water-dispersable orgar~ic binder within the mixture. In many cases, some of the water actuaily reacts with and becomes chemicaily bound within the organic binder. In other cases it may be more loosely bound to the organic binder, often by mearls of hydrogen bonding. Certain amounts of water may aiso react with other admixtures within the mixture, such as 1l~ y settable binders or other materiais which chemicaily react with water.
The water aiso serves the function of creatmg a moldable mixture having the desired rheologicai properties, including viscosity and yield stress. These properties are 35 generai ways of r~lJlu,.illldtill~; the "w~ db;lily" or flow properties of the moldable mixture.
In order for the moldable mixture to have adequate w~ dhili~y, water must generaily be included in quantities sufficient to wet each of the inorganic aggregate particles, fibers, or other solid particles, to solvate or at least disperse the organic binder, wo 95121056 E~~
~17~27~ ~

and to at least partially fill the interstices or voids between the particles. In some cases, such as where a dispersant or a lubricant is added, adequate ~.JIk~;li~y can be maintained while using less water initially.
The amount of water that is added to the moldable mixture must be carefully balanced so that the mixture is sufficiently workable, while at the same time ~C~0~;11;4ill~
that lowering the initial water content increases both the green strength and the final strength of the hardened product. Less water results in a stronger final product because the total porosity is reduced during the molding processes. Moreover, if less water is initially mcluded in the moldable mixture, less water must be removed in order to cause the molded product or sbeet to harden.
The appropriate rheology to meet these needs can be defined in terms of yield stress. The yield stress ofthe moldable mixture is in the range from about 2 kPa to about 5 MPa, preferably in the range from about 100 kPa to about I MPa, and more preferably in the range from about 200 kPa to about 700 kPa. The desired level of yield stress can be adjusted and optimized to the patticular molding process being used to fomm the sheet and hinges made therem.
In some cases it may be desirable to initially indude a relatively high amount of water in light of the fact that excess water can later be removed by heating the molded sheet during or shortly after the molding process. ~ , orle of the important features of the present invention as compared to the nl~-fa ,lh.c of ,u., . . ' paper is that the amoumt of water initially within the moldable mixture is far less than the amount rlormally found in fiber slurries used to make cvll~ Lvllal paper. This results in a mixture having far greater yield stress and form stability compared to paper-making slurries. The result is that the total amount of water that must be removed frvm the moldable mixture to obtain a self s.,~uulLh~ material (ie., a fomm stable material) is much less m the case of the mixtures of the present invention compared to the slurries used to ,. ---- r~ CUI-~. - ' paper. In fact, Cull~. - ' paper-making slulries have virtually no form stability until they have been dewatered to a sigluficant degree.
The sizes of the individual aggregate particles and fibers can be selected in order to increase the patticle packing density of the resulting moldable mixture. The amount of water that must be added in order to obtain a moldable mixture having a patticular rheology or yield stress will, to a large extent, depend on the ~Jal li.,l~ density.
For example, if the particle-packing density of the moldable mixture is 0.65, water will be mcluded in an amount of roughly 35% by volume in order to ~-h ~ fill the interstitial voids between the particles. On the other hand, a Idable mixture having a ~17~272 wo 95/21056 particle-packing density of 0.95 will only require water in an amount of about 5/~ by volume in order to s~hct ~ ly fill the interstitial voids. This is a seven-fold decrease in the amount of water that must be added in order to cllhctontiolly fill the interstitial voids, which influences the rheology and w~ lfilily of the moldable mixture. Theactual particle packing density will generally range bet veen these two extremes.
In light of the foregoing, the arnount of water tbat should be ædded to the mixture will depend to a large extent on the level of particle pæking density within the mixture, the arnount of water-dispersable binder that is added, as well as the desired rheology of the resultant moldable mixture. Hence, the amount of water that will be added to forrn tbe moldable mixture will range from as little as 5% to as high as 50% by volume of the moldable mixture. The exact amount of water will greatly vary depending on the volurne and identity of other 4 " ~ and adrnixtures within the mixture. One skilled in the art will be able to adjust the level of water to obtain adequate workability for any given r ' ' 3process.
It is preferable in most cases to include the minimum arnount of water that is required to give the moldable mixture the desired level of w~l~ilily, and thereby reduce the arnount of water th2t must be removed from the processed sheet. Decreasing the amount of water that must be removed generally reduces the cost of r 1~ since removing water requires energy. N~ , the ~ - - used in the present invention include far less water, even at the upper ranges of water inclusion, compared to slurries used to make paper, which generally contain more than 95% water by volume.
G. D`-The term ''d;..~ '' is used herein to refer to the class of materials that can be added to reduce the viscosity and yield stress of the moldable mixture. A more detailed description of the use of dispersants may be found in the Master's Thesis of Andersen, P.J., "Effects of Organic S~ e Admixtures and their t`t mr~mPntC on Zeta Potential and Related Properties of Cement Materials" (The r~yl~alfi~l State University Materials Research LaboMtory, 1987). For purposes of disclosure, the foregoing Master's Thesis is ill~,UII ' ' herein by specific reference.
~5 Dispersants generally work by being adsorbed onto the surface of the aggregate particlesand/orintothenearcolloiddoublelayeroftheparticles,~uL~. '~l~ifhydrauliccement particles are added. This creates a negative charge on or around the surfaces of the particles causing them to repel each other. T_is repulsion of the particles adds "lubrication" by reducing the fnction or attractive forces that would otherwise cause the WO9~/21~56 S particles to have greater interaction. Hence, the packing density is increased somewhat and less water may be added initially while ~ the workabilit~ of the moldable mixture.
Greatly reducing the viscosity and yield stress may be desirable where plastic-like properties, COI~ a, and/or forrn stability are less imporLant. Adding a dispersant aids in keeping the moldable mixture workable even when very little water is added.
N~ v~,. t~ J, due to the nature of the coating .., ~ .... of the dispersant, theorder in which the dispersant is added to the mixture can often be critical. If cerLain water-dispersable orgaoic binders (such as Tylose~) are used, the dispersant should be added to a mixture containing water and at least part of the inorganic aggregates first and then the binder should be added second. Otherwise, the dispersant will be less able to become adsorbed onto the surface of the aggregate particles because the Tylose:1~1 will first be ill~,~_la;l)ly adsorbed, thereby forming a protective colloid on the surface and thereby preventing the dispersant from being adsorbed.
A preferred dispersant is sulfonated , ' ' -fi -' ' ' ~l. . an example of which is marketed under the trademark WRDA I g, which is available from W. R Cirace, Inc. Other dispersamts which can also work well mclude sulfonated melamine~ ' 'ig Ir and pol~ di~, acid.
The dispersants, . ' ' withm the present inventjon have sometimes been referred to in toe concrete industry as "~ " In order to better distinOuish dispersants from other rheology-modifying agents, which often act as p~ rti,-i7rrr~, the term "~ . " will not be used in this a~
The amount of added dispersant will generally r~mge up to about 5% by weight of the water in toe moldable mixture, more preferably in the range from about 0.5% to about 4% by weight, and most preferably within the range from about 1% to about 2%
by weight. The arnount of added dispersant will generally range up to about 3% by volume of the total solids content in the i O "~/ filled structural matrix, morepreferably within the range of between about 0.1% to about 2% by volume, and most preferably within the range of between about 0.2% to about 1% by volume.
H. Air Voids Where insulation, not strenOQth, is the overriding factor (~.e., whether it is desired to iosulate hot or cold materials), it may be desirable to ...~ , tiny air voids within the structural matrix of the sheets in addition to liolll~. _' aggregates in order to wo ssr2l0s6 ~ 2 ~ ~ r .,.J.. c ~ - .

increase the insulating properties of the sheet or article made therefrom. The of air voids into the moldable mixture is carefully calculated to impart the requisite insulation ~ without degrading the strength of the sheet to the pomt of nonutility. Generally, however, if insulation is not an important feature of a particular product, it is desirable to minimize any air voids in order to maximize strength and minimize volume.
In cerLain ~ LC,~ air voids may be introduced by high shear, high speed rnixing of the moldable mixture, with a foaming or stabilizing agent added to the rnixture to aid in the i~r~n~ Yti~n of air voids. High shear, high energy mixers are ~J~Li~ ly useful m achieving this desired goal. Suitable foaming and air entraining agents include commonly used r ' One preferred surfactant is a pOlyy.,!J~iv~ alkylene polyol, such as M.,o~ Foarn Liquid.
In, .. ;.. I ;.. with the surfactant, it will be necessary to stabilize the entrained air within the material using a stabilizing agent like Mearlcel 3532~, a synthetic liquid arlionic ~ Jf ~ solution. Both M~ c~,'r amd Mearlcel~ are available from the Mearl Corporation in New Jersey. Another foarning and air-entraining agent is vinsol resin. In addition, the organic polymeric binder can act to stabilize the entrained air.
Different ~~ agents and stabilizing agents impart different degrees of foam stability to the ~ filled mixture, and they should be chosen in order to impart the properties that are best suited for a particular r ' 1 process.
Foam stability helps maintain the dispersion, and prevents the AL,J~ ,"
of the air voids within the I I ' I moldable mixture. Failure to prevent the of the air voids actually decreases the insulation effect, and it also greatly decreases the strength of the hardened moldable mixture. Raising tbe pHI mcreasing the t ~ "' of soluble alkali metals such as sodium or potassium, adding a stabilizing agent such as a pOl~ rheology-modifying agent~ and carefully adjusting the of surfact~mt and water within the moldable mixture all help to increase the foam stability of the mixture.
During the process of molding and/or hardening the moldable mixture, it is oftendesirable to heat the moldable mixture in order to increase the volume of the air void ~5 system. Heating also aids in rapidly removing significant amoumts of the water from the moldable mixture, thereby increasing the green strength of the molded product.
If a gas has been l.lcull ' mto the moldable mixture, heating the mixture to 2500C, for example, will result (according to the ideal gas equation) m the gas increasing its volume by about 85%. When heating is ~lu~lv. , it has been found desirable fûr WO 95/21056 P~
~ 40 the heating to be within a range from about 100C to about 2500C. The upper limit is set by any adverse reactions within the moldable mixture that might occur, such as the burning of the fibers or orgaluc binder. More UII~JVI hul~ly, if properly controlled, heavng will not result in the cracking of the st~uctural matrix of the sheet, or yield in the surface texture of the sheet.
Another foamirlg agent is a mixture of citric acid and hir~rbnn~t~, or bicarbonate that has been processed into small granules or particles and coated with wax, starch, or water soluble coatings. This can be used in void formation two ways: (I) to react with water and form C02 gas in order to create a cellular foa}n structure within the innrgpnir~11y filled matrix; or (2) to pack the particles as part of the matrix and ~fter hardening the matrix remove the foam particles by heatirlg the product above 180C, which causes an c '~ ' ~' , of the particles, leaving behind a well controlled cellular lightweight structure.
In other ~ . ' where the viscosity of the moldable mixture is high, such as is required irl certain molding processes, it is much more difficult to obtairl adequate numbers of air voids through high shear mixing. In this case, air voids may ~t~,ll~U~
be introduced into t&e moldable mixture by adding an easily oxidi2ed metal, such as aluminum, ~ zinc, or tin to a r~ixture that is ei&er naturally allcaline (such as a mixture containing hydraulic cement or calcium oxide) or one that has been made alkaline by t&e addition of a strong base, such as sodium hydroxide. This reaction results in t&e evolution of tiny hydrogen bubbles throughout &e moldable mixture.
It may further be desirable to heat t&e mixture in order to initiate t&e chemical reaction and increase t&e rate of formation of hydrogen bubbles. It has been found that heating the molded product to ~ , in t&e range of from about 50-C to about 100C, and preferably about 75C to about 85C, effectively controls t&e reaction amd also drives off a sigluficant amoumt of the water. Again, this heating process can be controlled so that it does not result in &e ;..~uuu~.liull of cracks into t&e matrix of the molded product. This second met&od of i..uudu~,;..~ air voids into the structural matrix can also be used in cnnj~mrfi~n wi&, or in place of, t&e iu.l~udu~liu.. of air through high speed, high shear mixing in t&e case of lower viscosity moldable rnixtures used in some molding processes.
Finally, air voids may be introduced into t&e moldable mixture during t&e molding process by adding a blowing agent to t&e mixture, which will expand when heat is added to the mixture. Blowing agents typically consist of a low boiling point liquid and finely divided calciuln carbonate (chalk). The chalk and blowing agent are unifomlly ~ wo 95121056 ~ 1 7 9 2 7 ~ s c mixed into the moldable mixture and kept under pressure while heated. The liquidblowing agent penetrates into the pores of the individual chalk particles, which act as points from which the blowing agent can then be vaporized upon thermal expansion of the blowing agent as the pressure is suddenly reduced.
During the molding or extrusion process, the mixture is heated while at the sametime it is CUIll,ulc~ ,.i. While the heat would normally cause the blowing agent to vaporize, the increase in pressure prevents the agent from vaporizing, thereby hlll,uul~ily creating an . . "' When the pressure is released after the molding or extrusion of the material, the blowing agent vaporizes, thereby expanding or 'iblowing" the moldable material. The moldable material eventually hardens with very finely dispersed voids throughout the inrrg~nir~lly filled structural matrix. Water can also act as a blowing agent as long as the mixture is heated above the boiling point of water and kept under pressure of up to 50 bars.
Air voids increase the insulative properties of the sheets amd other articles made tberefrom and also greatly decrease the bulk density amd, hence, the weight of the fmal product. This reduces the overall mass of the resultant product, which reduces the amount of material that is required for the r ' C of the sheets and which reduces the amount of material that will ultimately be discarded in the case of disposable sheets or containers made therefrom.
1. 5~Q~
The sheets and containers that employ the hinges of the present invention may also have sealing materials or other protective coatings applied to their surfaces. Most coatings are applied with a solvent so that uporl C~ Jul~liull of the solvent the coating material remains on the surface of the sheet or container.
Appropriate orgarlic coating materials mclude melamine, polyvinyl chloride, polyvinyl alcohol, polyvinyl acetate, pol~ ' ', hJLu~,ulu~,~h.l.,lllJh,CIIUIûSe,pol~ ~Iyl~ glycol, acrylics, ~1~ , p~ , polylactic acid, pOI,~,IL.~
Biopol~9 (a pol~ Lu~' ~ Lu~ ~ . ' copolymer . -, r~ by lCl in the United Kingdom), waxes (such as beeswax or petroleum based wax), ~ m~ rS, pcl~ly' latex,syntheticpolymersincludingI :~ir~"~ polymers,ormixtures thereof.
Appropriate inorgarlic coating materials mclude calcium carbonate, sodium sihcate, kaûlin clay, silicon oxide, aluminum oxide, ceramics, mica, and mixtures thereof.
These may also be mixed with one or more of the organic coatings set fûrth abûve.

wo 95~21056 r~"-,~ S l .
21~9272 42 Another type of coating that may be placed on the surface of the materials used in the present invention is a reflective coating such as metal flake coatings for reflecting heat into or out of a container. Such reflective coatings are readily available, but their aylJli~,d~ilil~ to i ~ ly filled materials is novel.
In some cases, it may be preferable for the coating to be rl~r~tr~mr~r ~1~ fmTr-a~lr or waterproof. Some coatings may also be used to strengthen piaces where the ly filled sheets are more severely bent, such as where the sheet has been scored. ln such cases, a pliable, possibly ~ tr/mrnr, coating may be prefer~ed. Besides these coatirlgs, any appropriate coating material would work depending on the application involved.
For exarnple, a coating comprised of sodiurn silicate, v.~hich is acid resistant, is a particularly useful coating. Resistance to acidity is important, for example, where the container is exposed to foods or drinks having a high acid content, such as soft drinks or juices. Where it is desirable to protect the container from basic substances, the containers can be coated with an ~ i polymer or wax, such as are used to coat paper containers. If the sheets are used to r ' ~ containers or other products intended to come into contact v~ith foodstuffs the coating material will preferably comprise an FD.~ L~ coating.
The coatings may be applied to the sheets using any coating mearls known in the art of paper or cardboard making. Coatings may be applied by spraying the sheet,container, or other object with any of the above coating materials, or it may beadv~l~O_v.w to apply the coating by dipping the sheet, container, or other object into a vat containing an r~ . coating material. In the case where a coating material issprayed onto the surface of a sheet, the coating material may be spread or smoothed by means of a doctor blade which is held a particular distance above the sheet, or which rides directly on the sheet surface.
In addition, coatings may be coextruded along with the sheet in order to integrate the coating process with the extrusion process. In other cases, the coating can be applied to the surface of the sheet by means of a gravure roller, often in, ~ with a doctor blade in order to smooth or adjust the thickness of the coating.
Il. III~iGEs As discussed in rnore detail below, a score, ~ r '' , or preformed bend is made in an; " ~ y filled sheet to produce a hinge integrally formed into the sheet.
The purpose ofthe score or perforation is to create a location on the sheet where the sheet wo 95/21056 7~ 2 7 2 r~ s ~ .
S can be bent or folded. This creates a "hinge" within the sheet with far greater bendability arld resilience tnan possible with an umscored or ~~ sheet. The hinge of tbe invention may be bent up to an angle of about 90o, 1800, or 360~ without ,..~
fracturing the .. ~ filled matrix, depending on the type of score used in forming the hinge.
A certain amount of tensile elongation is needed in order to give the "~, filled material bendability. Elongation is deflned as the increase in length of a bar or section of material under test expressed as a percentage difference between the original length and the length at the moment of rupture. Expressed in a forfnula, percent elongation equals lOO(LfLo)/Lo, wherein Lf is the final length at fracture and Lo is the IS initial lengtn at rest. Typically, a material cannot exceed its percentage elongation without breaking.
In the present invention, the percent elongation of the ~ "f~,t--' ~ filled material irlcreases as tne thickness ofthe material decreases. Conversely, as the thickness of the material increases, the elongation decreases. The fibers utilized in the material contribute to the bending of the structural matrix by increasing the elongation of the matrix before fracture. As more fibers are utilized, the percent elongation of the material is increased.
Anotber way to express the bending properties ofthe ~ filled material is through the bending radius of the material. The minirnum bending radius (rmjn) equals the elasticity modulus (Eo) times the thickness of the material (t) divided by t vo times the tensile strength (r,) of the material. This can be expressed m the following equation:
rmjn = Eo~t)/2r,. This means that if more fibers are put into the material, the terlsile strength goes up amd the elasticity goes down, so the material can bend in a very small radius. When the material has a higher elasticity, then a higher tensile strength is needed to bend the material in a desired manner or the thickness of the material must be decreased.
The hinge of the present invention may be a "living" hinge or a " I ~lf,"
- hinge. A living hinge has a flexible matrix and may be bent multiple times without breakage or fracture of the material forming the hinge. A nonliving hinge is less flexible and causes a hinged material to stay in place when bent. The matrix of a nonliving hinge will weaken when repeatedly bent and cam eventually break apart. Preferably, a nonlivmg hinge of the present invention would have a low fiber content with a coating over the surface of the hinge. The coating may be sprayed onto the surface of the nonliving hinge after the hinge has been formed. When such a nonliving hinge is bent, wo95~21056 ~ 79272 r~"~ 5~ . ~
S the material of the hinge is deformed underneath the coating amd the coating holds the material together after bending.
Coatings can be applied to the surface of the sheet to make it more flexible andcam be applied to ~ ly soften the sheet or a hinge formed within the sheet.
Elastomer, plastic, or paper coatings can aid in preserving tne integrity of the hinge whether or not the underlying hardened structural matrix fractures upon bending at the hinge. When the binge is bent back, the material underneath the coating will bend or break. The only thing intact would be the coating on the surface.
The present hinge may also be designed so tbat it bends any number of different times before breaking, preferably I to 15 times. The hinge may also be perforated so that IS the material may be easily torn apart at the hinge location.
The materials utilized in the hinge may be varied in amounts and c~
in order to provide preselected properties for the hinge. For exarnple, the fiber content utilized may be varied so tbat the hinge is not as flexible if a lirnited number of bends is desired in the product utilizing the hinge. Also, a variety of different fibers can be utilized and the fibers can be aligned" ' or .,~J~h.~ spread out. The fibers can also be co-extruded with the ~ 'Iy filled material. Further, the thickness of the hinge may be altered or I . r. . ~ may be put in the hinge matrix. All of the above may be altered in various c.. ~ to provide specific ~ in the hinge.
One way of making the hinge of the present invention is by scoring the innr~r.~ ly filled material along a Eine after the material has been formed into a sheet.
Scoring is a process that displaces a given amount of material over a certain area by cutting or indenting the material with a steel plate or other device along a line, which aids in forming a bend or hinge at a E ~ ' location within the sheet. The score forming the hinge ofthe invention allows the sheet to be bent along the score up to about 180 from horizontal without fracture. The sheet preferably bends away from the score, which is different from paper-based materials that bend toward the score.
F~ ulc;, the hinge area of the ;...- ~ l,y filled sheet below the score actually becomes stronger as a result of the d ~ of the material at the score.
This 1...~. r.. -I ;.... of the material below the score line is depicted in Figures 1-3, which show cross sections of jnr~r~:mirslly filled sheets having various scores that are discussed in further detail below.
The hinge of the invention can be a~ ult~_ou~ly formed during the sheet ....... r-, . ; .. g process by scoring or perforating the sheet as it is being formed or soon thereafter. A score can also be cut into the surface of the sheet anytime after it is formed wo gS/21056 ~ 1 7 9 2 7 2 in order to create a line within the structural matrix upon which the sheet can later be bent.
Thus, the score can be made in the sheet while it is in the green state before the sheet is dry (e.g., while almost wet), in a serni-hardened state, or after it has become fully dried in order to form the hinge of the invention. For example, a flat sheet can be scored and for~ned mto the shape of a container and therl hardened, or can be allowed to harden and then scored and formed into the shape of a container. The time and location of the placement of a score or perforatiorl will depend upon the desired pulpose thereof and the properties of the inorganically filled material used.
The im r~oni~ y filled sheet will preferably be in a ' "y form stable state during the scoring or perforation process. This is desirable to prevent the score or perforation from closmg up through the migration of moist material thereirlto. Since scoring generally (and perforation always) involves cutting through a portion of the struc-tural matrix, the sheet can even be totally dry without the scoring or perforation process harming the sheet. In cases where a score is pressed rather than cut into the sheet surface, the sheet should be moist enough to prevent fracture due to the dislocation of the structural matrix.
Where the ... ~.. _11~ filled sheet has a relatively low fiber content (less than 15% by volume of the total solids), it is preferable to score cut rather than score press the sheet. Conversely, where the sheet has a relatively high fiber content (greater than 15%
by volume of the total solids), it is preferable to score press rather than score cut the sheet. Finally, 1, r r~ generally work well in sheets of any fiber content.
The pulpose of the score or perforation is to create a location on the int)rgoru~ y filled sheet where the sheet can be bent or folded. This creates a "hinge"
within the sheet with far greater bendability and resilience than possible with an unscored or, . ~ ' sheet. In some cases multiple score cuts or p.. r.. ~;.. ~ may be desirable.
The depth of the score cut will generally depend on the type of score, the thickness of the sheet, and the degree of bending along the score line. The scoring mechanism should be adjusted to provide for a score of the desired depth. Of course, the ~5 die tap should not be so large as to actually cut through the sheet or render the sheet too thin to withstand the anticipated forces (unless am easily tearable hinge is desired).
Preferably, the score cut should be just deep enough to adequately serve its purpose. A
- . of score cuts on alternate sides of the sheet may be preferred in some cases to increase the range of berlding motion.

wo 9S/21056 2~ 1 7 9 2 7 2 1 l,. 15 In most cases where a tlunner sheet (<I mm) is being score cut or pressed, the score vill have a depth relative to the thickness of the sheet that is within the range from between about 10% to about 50%, more preferably within the rarlge from between about 20% to about 35%. In the case of thicker sheets, the score cut will usually be deeper due to the decrease in bendability of the thicker sheet. Thicker sheet materials can be scored to a depth up to about 90% of the total thickness of the material. In other words, the thickness of the hinge material after scoring can be as small as 10% of the original thickness of the sheet.
Scoring makes the remaining cross section very thin, with a preferred thickness of the material forming the hinge being in the range of about 0.01 to I mm, and a most prefe~red thickness ir~ the rarlge of about 0.05 to 0.5 mm. The material Dllll~ " _ the hinge may be any tbickness but the scored portion formirlg the hinge is very thin so that it may bend without breaking.
The hinge ofthe invention formed by scoring can have a variety of shapes in thatthe score line side view profile can be square, _ ' , rounded, parabolic, sinusoidal, wedge, triangular, etc. The various shapes of the hinge design provide specific bending properties. Examples of the hinge design of the invention are depicted in Figures 1-3, showing that the hinge can be made from a single score, a double score, or a multiple score.
Figures IA, IB, arld IC show three ~ filled sheets 10, 12, amd 14 in cross section side views baving single scores 11, 13, and 15, IC.,lJ.,.Li~ , of different shapes. Score 11 has a triar~gular profile, score 13 has a rectangular profile, and score 15 has a rounded profile. Figures 2A, 2B, and 2C depict three sheets 20, 22, and 24 in cross section side views having double scores 21, 23, and 25, I~Li~ of different shapes.
Score 21 has a triangular profile, score 23 has a rectangular profile, and score 25 has a rounded profile.
Figures 3A-3F show six; ~ lly filled sheets 30, 32, 34, 40, 42, and 44 in cross section side views having multiple scores 31, 33, 35, 41, 43, and 45, .c .~ ly, of different shapes. Scores 31 and 41 have a triangular profile, score 33 h~s a rectangular profile, scores 35 and 43 have a rounded profile, and score 45 has a sinusoidal profile.
Scoring allows the innTg~ ly filled sheet to fold or bend along a single line up to about 90, preferably up to about 180 from horizontal without fracturing the structural material. ~vhen multiple scores are made in a sheet on both sides thereof, the sheet can be bent up to 360 by being bendable in half in both directions. Before the WO 9S/21056 ~17 g 2 7 2 r~l,o~

present invention, it was not possible to fold or bend inorganic sheet materials along a single line greater than about 10.
Figure 3G depicts an innrg~n;rPliy filled sheet 46 in a cross section side view having multiple scores 48 with rounded profiles on both sides of the sheet. This multiple scoring on both sides of sheet 46 enables sheet 46 to be bent along the score up fo about 360O without fracture. Thus, multiple scoring on both sides of a hydraulically settable sheet allows the sheet to be bent in half in either direction.
When the sheet is scored on one side, such as shown in Figure 1, the sheet is preferably bent away from the score. For example, if the score is made in the top of the material, then the material is bent d.J...,wald~. The bend is opposite the score such as shown in Figures 4 and 9. Double scoring of the sheet such as shown in Figure 2 provides a mechanism whereby the sheet can be bent in either direction without breaking.
In double scoring, the scores are preferably made on both sides of the sheet as shown in Figure 2 to provide bending both ways if desired.
It should be understood that while the ~ filled sheets will bend away from a score cut or I ~ the sheets will bend toward a score that is pressed intothe surface of the sheet. Thus, the sides of the sheet deflned by a score cut or perforation will close together on the side opposite the score cut or p~rfnrPfinn as shown m Figures

4 and 9. Conversely, like paper or cardboard products, the sides of the in~r~,onioo1ly filled sheet defined by a score pressed mto the sheet surface, as shown in Figure 7, will close together on the side of the sco}e.
Multiple scoring of the sheet such as shown in Figure 3 provides increased bendability (compared to single scoring) without breakage or fracturing of the sheet.
This is shown in Figure 4A which depicts sheet 50 having single score 57, and in Figure 4B which depicts sheet 54 having multiple scores 55. Sheet 50 is shown bent at amaximum angle ~ (e.g., 90O) which is less than the maximum angle ~ (e.g., 1300) Of sheet 54 having multiple scores. Multiple scores also allow sheets of a greater thickness to bend a greater amount, since each scored area of the sheet only has to bend a limited distance to provide the overall bending of the sheet. Multiple scores also provide for less stress on each scored area as the sheet is bent.
The scores are preferably integrally formed in the; ~ filled sheet with a die that stamps or cuts the score into the sheet. The die used in forming the score has the same profile shape as the specific score made such as square, 1l ~ ' rounded, parabolic, srnusoidal, wedge, triangular, etc.
.

wo gsn~os6 ~ 1 7 ~ 2 7 2 r~

It may sometimes be preferable to concentrate more fibers in the area where the score cut or perforation will be made to give greater strength and flexibility in the scored area that will be subject to ben&g. This can be ~ h. .~ by co-extruding a secondlayer of ~ 'Iy filled material containing a higher fiber content at ~,._.1. 1.... ,:....1 timed intervals to correspond with the location of the score cut or p~rfo~tinn rn addition, fibers can be placed on top of, or injected within, the sh!eet during the ~ or extrusion processes in order to achieve a higher fiber: at the desired location.
The hinge of the present invention can be formed at a Oo angle or parallel with the direction of the fibers in the sheet, or can be formed at various angles up to 90O or u.. u.. ll1i.,uku to the direction of the fibers. When the hinge is formed parallel to the fibers, the h~inge is weak. Such a hinge has minimum strength and maximum flexibility.
When the hinge is formed ~ to the direction of the fibers, the h~inge is strong.Th~is hinge has maximum strength and minimum flexibility. Thus, tbe desired strength and flexibility of the material at the hinge location can be optimized when a hinge is forlned at varying angles between Oo amd 90o to the direction of the fibers. For example, scoring of the sheet to form a inge is preferably done at a 1.. ~.1. t ....:...~A angle to the direction of the fibers within the sheet in order to optimize strength amd flexibility of the hinge.
The act of forming or densifying the "K~ lly filled matriX Lullc . ' ~'!/
increases the density of the fibers in the area, preferably without damaging the fibers. ln ~,UIIV. " I tree paper, the act of scoring veakens the fibers therein to cause them to bend. In contrast, scoring of an " "~, filled material causes the fibers beneath the score line to densify in the material and thus ~ the bend area of the material.
For example, if the material has about 20% by volume of fibers, the area below a score line can increase up to about 40% by volume if the score depth is about 50% of the material thickrless, because of the ~ ; of the material below the score line.
A score or perforation c~m be made on the: ~y~ y filled sheet through the processes shown in Figures 5-8 in order to define a line upon which the sheet may fold or bend. As shown in Figure 5, a score cut 68 can be made on sheet 69 by using a knife blade cutter 70 mounted on a score press (not shown). As shown m Figure 6, a score cut 72 carl be made on sheet 73 by using a continuous die cut roller 74. A score 76 may be pressed into sheet 77 by using a scoring die 78 as shown in Figure 7. The pressed score is made at a controlled rate, depthl amd pressure when the sheet is in a wet or semi-dry condition. If the sheet is flexed at the score while wet, a living hinge is forrned.

~ wo95/21~\56 ~ } 272 r_l,o. 5;

S E`clrulaliul~ 80 can be made in sheet 81 using a perforation cutter 82 as depicted m Figl~re 8.
A score or perforation within the sheet creates a better fold line or hinge for a number of reasons. First, a score provides a place where the sheet might more naturally bend or fold. Second, a score makes the sheet at the score thinner tham the rest of the lû sheet, which reduces the amoumt of lengthwise elongation of the surface while bending the sheet. rhe reduction of surface elongation reduces the tendency of the structural matrix to fracture upon being folded or bent. This is shown in Figure 9, which depicts sheet 84 bent along score cut 85. Third, the score cut or perforation allows for a controlled crack formation or failure within the matrix in the event that fracture of the structural matrix occurs.
The hinge of the present invention can be used on a variety of different containers made from innrgen;r~lly filled materials that require a pivoting .,... l, ~
to open and close the container a number of times. An example of such a container is the "clamshell" container 90 depicted in Figures 10-12. Container 90 has upper shellmember 92 which is pivotally attached to a lower shell member 93 by a hinge 94. Hinge 94 can be formed during the . ~ . of container 90 by scoring the material forming container 90. Container 90 is used to store fast food items such as I._...l t, ~ or other '-.;.,1.~ after they have been made amd are delivered to the customer.
The hinge of the present invention may include a pulp containing material such as a pulp sheet or paper wbich has been applied to the desired hinge area. The pulp sheet reinforces the hinge area by adding more fiber thereto and provides easier bending of the hinge area. This permits less fiber to be used in the rest of the matrix, if desired. The pulp sheet also acts as a protective covering over the hinge a, . ' ~ dust from breakage of the material in the hinge area if this occurs.
Preferably, a paper strip is applied to the material forming the hinge area during the molding operation that forms the container. The paper strip can have a thickness as low as 0.01 mm. The paper strip is preferably fed into the molding machine I!'- r 1' ' to the flow of innrg~ni~lly filled material. The molding force adheres the paper strip to the matrix of the hinge area. In a preferred ~ ' ' t, the paper is applied to the inner side of the hinge area and a score is made on the outer side of the hinge area. l~is is shown m Figure 12, which depicts clamshell container 90 m an open position, with paper strip 95 disposed on the inner side of hinge 94, which pivotally connects shell members 92 amd 93. In an alternate c,llL ' t, a paper laminate may be applied to the entire ilmer surface of the container, providing fiber .~ to wo gsmos6 ~ ~ 7 2 7 2 r ~lm~
i50 the inside of the container. This provides flexibilitv and toughness to the container, as well as reinforcing the binge area. The paper laminate itself can serve as the hinge, providing flexibility and a very bigh fiber content in the hinge area, Ond ,.:..r.,,....,.. ~
of the remaining part of the container. This allows less fiber to be used in theinrr~ ly filled material used to form the container.
It is also possible to make the binge of the invention by prebending or flexing an inr,rgpnirqlly filled matrix in a semi-dry condition where the binge is to be formed.
In this way, memory is being introduced into the material and a living hinge is formed.
When the material is bent in a semi-dry condition, there is not total adhesion of tbe binder onto the fibers, so that by bending it in the predried condition the actual hinge rnPrhqnic n is being shaped into the material. Fibers in the material are pulled out of the matrix slightly to weaken the bond which gives better toughness and flexibility so as to allow pivotal movement at the bend point of the material. When the material hardens, the bend point or hinge is 1~... .,I. ~J by the material so that it bends in tbe same place every time.
The binge of the present invention can also be made by localiq~ ed "creping" of the; ..~ lly filled sheet material, which provides for improved bending or folding of the material. The sheets are creped much like ordinary tree paper in order to provide a higbly extensible sheet that is capable of absorbing energy at sudden rates of strain, and to provide improved bending of the sheet. Cu~ ' creping cen be performed either at the wet press section of a paper machine (wet crepe) or on a Yankee dryer (dry crepe).
Although the exact parOmeters of either a wet or dry creping process will differ between the ;.. "~ lly filled sheets and tree paper, one of ordin ry skill in the art will recogni e how to adjust the creping process in order to obtain creped innr~,qnirqlly filled sheets. The creping process would be expected to work better as the fiber content of the sheets is increased, since increased fiber content facilitates the sealing of the pores in the material and increased hydrogen bonding of the fibers.
A preferred binge of the invention has an , "!/ filled structural matrix comprising an orgaiqic polymer binder having a ~ in the range from about 1%
to 50% by volume of the total solids in the ;~ y~ lly filled structural matrix; an inorgaiqic aggregate material having a .f . .~ -~ ;.. in the rOnge from about 40% to 98%
by volume of the total solids in the; . .- -- ~ lly filled structural matrix; and a fibrous material having a crnr~ ntrqtinn in the rOnge from about 0.5% to about 50% by volume of the total solids in the inr~rg,qr~irqlly filled structural matrix. The inrr~,qni~qlly filled ~ wo ssnlos6 ~17 !~ 2 ~ 2 structural matrix of the hinge has a thickness of about 0.01 to I millimeter, preferab~y about 0.05 to 0.5 millimeter.
m. .'~mi'l;.TS. CONTAll~T~.R~- AND OTllF.R PRODUCTS
The term "sheet" as used in this ~ ri ~;. and the appended claims is intended to include any ellhet~ntiolly flat, corrugated, curved, bent, or textured sheet made using the methods described herein. The only essential ~ r~ limitation is that the st~uctural matrix of at least part of the sheet comprises a highly i~ -- - y,c- ~lly filled composite having a water-dispersable organic binder. The sheet may include other materials such as paper, organic coatirlgs, ink, or other orgal3ic materials in addition to the highly inl~rg^-:^olly filled/organic binder matrix portion.
The sheets used in the present invention carl have greatly varying ~
depending on the particular application for which the sheet is intended. The sheets can be as thin as about 0.01 mm arld as thick as I cm or greater where strength, durability, and or bulk are important ~.- 'rl- ~ In addition, the sheets may range in density from as low as about 0.6 g/cm3 to as high as about 2 g/cm3. Generally, higher density sheets are stronger while lower density sheets are more insulative. The exact thickness or density of a particular sheet carl be designed L ~ ' ' in order to yield a sheet having the desired properties at a cost which allows the sheets to be produced in an ~c~n~mir olly feasible manner.
The term "container" as used in this ~1 :ri- - ;.. and the appended claims is intended to include any a~ticle, receptacle, or vessel utilized for storing, r1ierPncir~, packaging, portioning, or shipping various types of products or objects (including, but not limited to, food and beverage products). Examples of such containers includedisposable and ,..~...1;~1...- 1,l~ food or beverage containers, boxes, jars, bottles, plates, trays, cartons, cases, crates, dishes, egg cartons, straws, envelopes, "clarnshell" cont~3iners (including but not limited to hinged containers used with fast-food ' ~;. L~ such as 1 -- -1.---~;..~), cracker boxes, rice boxes, cereal boxes, corrugated boxes, sandwich containers, frozen food boxes, milk cartons, fruit juice containers, beverage carriers (including but not limited to vv~ basket-style carriers, and "six pack" ring-style carriers), ice cream cartons, cups (including but not limited to disposable drinking cups, two piece cups, one piece pleated cups, and cone cups), french fry containers used by faet-food outlets, fast food carryout boxes, bags (including but not limited to bags v~ith an open end such as grocery bags, bags within cartons such as a dry cereal box, and ~l~g272 WO95/210S6 I~

5 multiwall bags) sacks, ~ UU.. i casing, cigar boxes, c~ boxes, boxes for cosmetics, or other types of holders.
The hinge of the invention may also be utilized in making storage boxes with flaps. Single sheets can be scored to for n the hinge as well as multiple sheets used for liners in a box.
In addition to integrally formed containers, ~-.- '- ,.. l products used in with cont2iners are also intended to be included within the term "container".
Such p}oducts include, for example, lids, liners, partitions, wrappers, cushioning materials, utensils, and any other product used in packaging, storing, shipping,portioning, serving, or dispensing am object within a container, or wrapping an object held within a container.
In addition to sheets and containers, any object that can be formed using the highly ,, lly filled sheets and hinges described herein are also within the scope of the present invention. These include such disparate objects as, for example, model airplanes, toys, venetian blinds, rain gutters, shirt packaging forms, temporary car window shades, book covers, folders, and an endless variety of other objects.
An; ~ filled matèrial apparatus of the invention comprises a first member, a second member adjacent to the first member, and means for flexibly joining the first and second members so that the first and second members can be pivotally moved about the joining means relative to one another. The joining means such as a hinge allows the frst and second members to be pivotally moved behveen a first position wherem the first and second members are in straight alignment with one another and a plurality of other positions wherein the first and second members form an amgle in relation to one another. The first and second members preferably have a .. . ~
resistance to bending and elongation within a first range, and the joining means has am area of reduced mechanical resistance to bending and elongation within a second range that is less tham the first range. The first and second members also have a thickness within a first range and the joining means has an area of reduced thickness within a second range that is less than the first range of thickness.
The containers that use the hinge of the present mvention may or may not be classified as being disposable. In some cases, where a stronger, more durable cu.~llu,liu.. is required, the container might be capable of repeated use. On the other hand, the containermightbe . . ~r~ I ... r~l in such a way that it is econom cal to use once wo ss/2l0s6 ~3l 79272 and then be discarded. Such disposable containers can be readily discarded or thrown away in Cu~ iul.al waste landfill areas as an ~IIV;l. "~/ neutral material.
The structural matrix within the molded containers will preferably have a thickness less than about 20 mm, more preferably less than about 5 mm, amd most preferably less than about I mm. In certain ~ ...~.,).l:,.,...t~ the thickness could even be less than 0.1 mm, especially where a more paper-like material is preferred.
Products that utilize an accordion type hinge can be made with the hinge of the invention. This falls within the definition of a hinge as used herein since an accordion hinge can be bent. An accordion hinge goes up and down in a wave-type motion. Inmaking an accordion hinge, an innrga.lir~-lly filled material is embossed so that .,.. , .. ~ ;.. or waves æ put into the material where desired. An accordion hinge may also be made by scorin the material so that waves are thin and thick in an alternating fashion. Preferably, there are I to 6 waves in the accordion hinge. One product using an accordion hinge is am accordion file, which can be made usmg the hinge of the present invention. An accordion file uses a type of hinge that can be expanded or contracted depending on how many papers are filed inside. Flexible straws cam also be made with the present hinge in an accordion shape, and flexible ducts cam be made using the hinge of the present invention.
The phrases "mass ,UlUdU-~;bl~." or ",-~ in a "~.ull~ ,;al" or "~ " manner are intended to refer to a capability of the sheets and containers described herein to be rapidly produced at a rate that make their ,-, ,--r~ c ~r~ ly C....-~ to sheets and containers made from other materials, such as paper, cardboard, PC)I~ GII~.7 or metal. The sheets and containers used in the present invention are fommed from rnnovative . that solve the prior art problems of a high percentage of inorganic aggregates into the matrices of products which can be rapidly r ' ~ by machine, rather than individual hand " - r ~, _ of one product at a time (such as "throwing pots").
The sheets, containers, and other objects made therefrom are mtended to be - . . v~ in the ' ~l ' vith such articles currently made of various materials such as paper, plastic, ~c,ly~lylcll., or metals. Hence, the sheets (and objects made therefrom) used in the present invention must be ~ - ' to (i.e., the cost will usually not exceed a few cents per item). Such cost restraints thus require automated production of thousands of the articles in a very short period of time. Hence, requiring the products of the present mvention to be "~/ mass produced is a sigmficant limitation on the qualities of the materials and pr~ducts.

wo95/21056 1_1")., s 2i~g2~f'~ --A sigluficant advantage of the containers amd hinges of the present invention isthat they do not require or result in the emission of ~ ~v;~ "y harmful or ozonedepleting chemicals. In addition, when disposed of into the ear~, such containers do not persist in the ~llvhu..lL~ as do foreign materials which must biodegrade (often over a number of years) before they become CllV;lul--l-. lll~lly imlocuous. Instead, the waste containers are essentially composed of the same materials already found in the earth.
Under tbe weight and pressure of typical landfills, such containers will crumble and break down into an . ~l~hul~ I!y neutral powder that is the sarne as, or at least compatible with, the dirt and rock already found within the landfill.
Thus, if highly O "y filled sheets (or products made therefrom) are discarded into a landfill, they will break down into a fine, mainly inorganic, powder under the weight of the other garbage present. If discarded onto the ground, the forces of water and wind, and even fortuitous cu."~ ., forces such as from cars running over tnem or people stepping on them, will cause the ;. ,... O,., :. lly filled waste materials to degrade and be reduced to a largely inorgaluc, hannless granular powder in a short period of time relative to the time it usually takes for the typical disposable paper or p~l f .,lyl c.l.
sheet or container to decompose under the same ~ Whatever organic substances remain after the ~ L ~ of the sheet are minimal and will preferably be l rf~f o l l l lf F~L ~llllul~, the containers are fully recyclable with a minimum amount of energy and effort. Unlike paper and plastic products, which require a substantial amount of processing m order to restore them to a suitable state as raw starting materials, in~ lly filled material products can be ground up and recycled by merely reincor-porating the grindings into new containers as an aggregate r f. PROCESSING METIIODS AND TECR~IOUE~
The process for forlning the containers and hinges of the present invention withjnr~rg~nir~lly filled materials can use a variety of methods which haYe been applied to plastic materials. The term "molding" as used herein includes the variety of molding, casting, and extrusion processes discussed herein or that are known in the art. These methods include roller casting, high pressure extrusion, ram pressing, hot isostatic pressing, injection molding, ~ ."..r.., ~ f~ and other casting and forming methods.
. . The hinge of the present invention can be made in ~ lly filled sheets or containers having properLies similar to those of paper, plastic, or i' . " ' metals. The sheets can be ' ly used to form a variety of oyects such as food or beverage ~ WO 95/21û56 7~ 2 7 2 1 ~I/U~

S containers, or can be stacked or rolled and stored for future use. During the subsequent process of forming the sheet into the shape of the desired object, it will usually b~
to remoisten the hardened sheet in order to t~ Ju~ y increase the flexibility and workability of the sheet to avoid splitting or cracking when the object is formed. This is p~ ~ true in the case where the sheet will be rolled or has been scored and is expected to make a ~ i ' '~ sharp bend during the container forming stage.
The underlying theory behind the prcsent invention is the rapid, continuous, and^cn^nmiræl formation of lit~ t~. _' t, ill~A~;VC sheets and hinges from a moldable "!~ filled mixture, which can be easily handled and rapidly ~ 1 in a C;aAI r ' ' ~ setting. The result is the ability to mass-produce in a very cost CU~ U~ iVe rnanner li~ ' t, thin-walled, form stable sheets, as well as containers or other objects made therefrom, having a structural matrix that includes an "~ filled material, rather than a paper, plastic, or ~ulJ~ c..e structural matrix.
The ;I ,. ,. ~; _ll y filled material can be formed into relatively tbin sheets or walls having roughly the same thickness as Cu.. ~ iullsl containers made from paper or styrofoam.
A method of making a hinge having an; .,~ .y filled structural matrix comprises the steps of miAxing a water-dispersable orgaric polymer binder, fibers, aggregate, and water in order to form a moldable mixture; forming the mixture into a form stable sheet of a I 't ' thickness; and scoring the sheet to form a hinge in the innrg~ liy filled matrix.
Figure 13 shows a schematic diagram of a process for molding containers made of _ 'Iy filled materiais that can utilize the hinge of the invention. The desired ~ .. ~... ..I~ such as organic binder, water, fiber, aggregate, etc. are placed in a mixer 102 through an inlet 104 and are blended to form a moldable miAture. This mixture is then directed to an extruder 106 and pumped through a die 108 intû a roll-stack 110 that flaKens the materiai into a sheet 112. The sheet 112 is then fed into a molding apparatus 114 to form the desired product such as a clamshell container. The formed sheet 116 is then directed through an oven 118 to dry the material. The formed sheet 116 `
is then sent to a cuKer machine 120 where the formed containers 122 are trimmed from E
formed sheet 116 and unioaded. The formed sheet 116 can be scored to form the hinge r of the invention at anytime during the process of making the containers. For exarnple, l the hinge can be molded into the sheet bet~veen the parts of the molding apparatus when t the container is formed therein wo95~21056 2 17 ~ 2 7 2 ~1/. 5 ~~ , 5 Inapreferredmethodoftheabove.. _ . r- I. ;. a process,therawmateriaisfor maicing the moldable mixture can be combined in a sigma-blade, icneading mixer system tilat will blend batches of material that are then deposited into the extrusion and calender system. Once the premixed material is deposited into the extruder, the materiai is auger fed into a chamber and extruded out through a Ic~ ulol siit about 42 inches wide and about 1/2 inch in height. The extruded materiai then passes through a series of heated rollers to produce a caiendered sheet materiai, which reduces the web thickness to a height of about 2 mm. The rollers are heated to provide a mold release and will aiso partially dry the sheet materiai as water vapor is driven off. The sheet is preferably formed by pressing it between maie and femaie molds using a vacuum forming apparatus.
A 64-cavity press can be used which operates at about 25 .;y.,l~alll~.~. Once the forLned sheet is dried, it can be die cut in a punch press.
In order for the; .. ~ filled materiai to exhibit higher flexural strength and/or . ' ~ the fibers can be aiigned or stacked instead of being randomly dispersed. It is preferable for the fibers to be laid out in a plane that is parailel to either of the two surfaces of the sheet or container wail. In some containers, it is preferable for the fibers within the container body to be Cll.~UIII~;.C ' ~ / or u~f~JIlc~,liul~lly aligned.
Simiiarly, the fibers within the bottom wall of the container can be horizontaily aiigned.
Such alignment of fibers is achieved either by roller casting, ram-pressing, extrusion, or differentiai pressure roller extrusion.
In order for the ~ "y filled material to be effectively molded, it is important that the materiai be form stable in the green state. The molded product shouid rapidly (preferably in three seconds or less) be able to support its own weight. Further, the materiai must harden sufficientiy so that it can be quicicly ejected from the mold.
Otherwise, the cost of molding may make the process l ' In addition, the surface of the molded article shouid not be too sticicy, as that wouid make the demolding process difficult and cause problems in handling and stacking of the molded articles.
There are severai . ~ to ~,u... ~.A.iullal molding processes that can be employed in order to ease the . - r~ process of molding; ~ lly filled materials. For examp~e, it is frequently desirable to treat the mold with a releasing agent im order to prevent sticicing. Suitable releasulg agents include silicon oil, Teflon~9, Deleronll9, and UHW~). Preferably, the mold itself wiii be made of steel or of a materiai with a very "siick" finish, such as Tef~on~9 or Deleron(l~). If the mold is made from steel, it will preferably be plated with either polished nickel or chromium. R~ ee it is important that the mold be kept hot (> 50~C) to create a thin layer of steam between the wo 95~21056 ~ 1 7 ~ 2 7 ~ r~ s~
S mixture and the mold to aid in demolding the product. The same effect can be achieved from the use of frictional forces. By spinning the head of the molding apparatus against the interior and/or exterior surfaces of the i.. ~r ~ ly filled material, any chemical and mechanical adherence (ie., stickiness) to the mold can be overcome.
During the process of molding the ;.,...~ ~lly filled mixture, it is often desirable to heat up the mixture in order to control the air void system and the porosity of the molded container. This heating process also aids in making the mixture form stable in the green state ( ' '~ after molding) by allowing the surface to gain strength quickly. Heating also aids in rapidly removing significant amolmts of water from the mixture. The mixture c_n be heated to a ~ from about SOoC to 2500C
IS during molding.
Although it is often preferable to coat rollers with any of the nonstick materials discussed above, it is more important to heat the rollers to prevent sticking of the material to the rollers. Typically the roller t~ L~ will be within the range from about 50C
to about 150C. Not only do the heated rollers prevent the innrg,or~irally filled material passed IL~-cLh u~h from sticking, but they also help the material to more quickly reach form stability.
The mixture that is molded to form the containers and hinges of the present invention is self-supporting during the green state and will maintain its formed state throughout the curing process. In addition, the mixture rapidly reaches a sufficiently high strength so that the molded containers can be handled and . ' ' using 1UII~ AIUI10l means.
After the ilmrg?~:^olly filled mixture has been molded, it may be necessary to bend, fold, or otherwise shape the cured or uncured material into the desired shape of a container. For example, a flat sheet may be folded into the shape of a box. For some ' " a box is most easily formed from a flat sheet that is scored and folded after the sheet has been cured.
A method of .. - .. r 1 .. g a bendable sheet having an i~ rgp ~lly filled structural matrix comprises the steps of mixing a water-dispersable organic polymer binder, fibers, aggregate, and water in order to form an ~ 'Iy filled moldable - 35 mixture; extruding the mixture through a die; forming the extruded mixture into a form stable sheet of a ~.._.I. ~... ":....~i thickness; and h_rdening the sheet to a significamt degree in an accelerated manner in order to quickly mcrease the yield stress of the i. .~ liy filled matrix. The sheet can be made bendable by cuttmg a score or perforation into a W0 95121~156 r~ 5 1 - ~
21~2~2 surface of the sheet that is ~ ly hardened, or by pressing a score into a surface of the sheet prior to drying and hardening while the sheet is wet.
V. MANUFACTURlNG .'~I~F.TS FROM MOLn~RT.F. IVITXTURF..'~
A CUII~ production sequence for .. -- -- r- 1... ,.~g sheets that can use the hinge of the present invention is set forth in Figure 14, including the apparatus for carrying out the following ,. ,r~ 1... ;"" steps: (1) mixing the moldable mixture; (2) extruding the mixture into a sheet, pipe, or other object through an _, r r ' ' extruder die; (3) passing the extruded sheet through a series of paired rollers in order to reduce the thickness and/or rmprove the surface qualities of the sheet, (4) at least partially drying the sheet by rolling it onto one or more drying rollers; (5) optionally ~ . the sheet while in a slightly moist condition in order to eliminate unwanted spaces within the ir~rgP~ slly filled matrix of the sheet and to increase the density and resulting strength of the sheet; (6) optionally drying the sheet after it has been ~.. 1.~. ~.. l (7) optionally finishing the sheet by passing it between one or more pairs of rollers, including one hard and one soft roller; and (8) optionally rolling the sl~h~tsntiAlly hardened and dried sheet onto a spool to form a roll which can be stored and used when needed. The above r ' ' ~ steps are discussed more fully below. A more detailed discussion of similar processes used to ~ ci sheets having a hydraulically settable structuralmatrix is set forth in the Andersen-Hodson Technology. For purposes of disclosure, this reference is ul.,uli ' herein by specific reference.
In the case where the moldable mixture is extruded into any object other than a sheet, it may be necessary to "ope~ up" the object into a sbeet, such as t ~, cutting a pipe to form a sheet. If another shape is extruded, other procedures (such as the use of additional rolling processes) may need to be employed. However, the same principles described herein would apply to other extruded shapes.
The semi ' ' ' or hardened sheets can be used much like paper or cardboard to ~ a variety of containers, printed materials, or other objects, or they can be rolled onto a spool or cut and stacked onto a pallet and stored until needed. The sheets can be scored or perforated in order to create a fold Ime, then folded and/or rolled into the desired shape of the container or other object. When folding or rolling the sheet, it will often be ad~ vu~ to remoisten the sheet in order to introduce temporary increased flexibility.
The rolled and/or folded sheet in the shape of a container or other object can be held together using any connection means known in the art. In some cases, the ends can ~ WO 95121056 ~ ~ ~ 9 2 ~ 2 P~

S be folded together or inserted into specially designed slots. In otber cases, it may be necessary to glue the cvllca~vl~dulg ends together using a&esion means known in the art. IAhese include glue, adhesive strips"1.~ .,. ,1,1 - ~;~ materials, or a . ~thereof. IAhe inorganically filled material sheets, containers, or other objects can be coated with a desired coating or printed on using means known m the art of paper, plastic, or pOI~a~lcl,. use. IAhis can be done at any ~ IU~ stage of the ~ _ prvcess~
A. r - The r~ t..re The fLrst step in the A ' C of sheets involves the formation of a suitable moldable ;,.. ~I~SA'''' ~lly filled mixture having the desired properties of workability and green strength, as well as strengtb, flexibility, toughness, and ~l~grA~ ility of the final hardened product. Using a llucluauuci u~ apprvach, one skilled in the art can select the r.. 1.. .. ~ as well as their relative r .. .1. -I ;.. ~ m order to obtain a moldable mixture having the desired properties.
Some of the properties considered to be generally desirable with regard to the moldable mixture are adequate wu.l~l,ililr, plastic-like qualities, and green strength for a given extrusion, rolling, and/or molding process. As set forth above, the level of water, water-dispersable organic polymer binder, and (optionally) dispersant will determine the level of workability and ~ALIu~ldl~;l;~y of the mixture, as will the other , ~vithin the mixture, such as aggregates, fibers, air entraining agents, etc. However, no one component will completely determine the rheology and other properties of the moldable miAture. Rather, each of the ~ - work together in an illtl ll~ ' ' fashion.
1. F.ffrrtof('~ ~q, on r~ r The amount of water that should be added to obtain a mixture having adequate WUII~ili~y and flowability will depend on the . and particle packing density of the inorganic filler, the amount of fibers, the identity and quantity of the organic binder, and the identity and quantity of other admixtures (such as VlAIJ~ ' r' ~;~A;7~rC~ or lubricants). In general, however, the addition of more water will decre_se the viscosity and yield stress of the mixture, thereby increasing the flowability of the mixture and decreasing the form stability of an object molded therefrom.
. The water-dispersable organic polymer bmder can greatly affect the rheology ofthe mixture depending on the identity, I ~ amd extent of gelation of the organicbinder. As set fûr~ abûYe, preferred orgarlic polymer bindera can rvughly be divided

6 ~ 7 ~2~

.
S irlto the following categories: ~ulya~ ~;~ based, protein-based and synthetic organic.
Within each of these broader categories are numerous ~ ' g~ and divisions. A
unifying feature of each of these materials is that they will generally dissolve in, or at least be fairly thoroughly dispersed by, water. Hence, they require adequate levels of water for their dispersion and activation (including gelation) within the moldable mix~ure.
N~ ~ ll.. l~, the organic polymer binders have greatly varying levels of water solubility or ~icr~r~ ility, as well as varying levels of viscosity and yield stress.
Organic polymers within the same class may have greatly varying viscosities depending on the molecular weight. For example, a 2% solution of Tylose~) FL 15002 at 20~C has a viscosity of about 15000 cps, while a similar solution of Tylose~D 4000 has a viscosity of about 4000 cps. The former greatly increases the yield stress and plastic-like properties of a moldable mixture, while the latter may act more as a lubricant or plastici~er.
Other orgarlic polymers react at different rates and different f' " '1'- ~ . ` within the water. Although many organic polymer binders such as Tylose~ neither u~
or J~l~...... ;~ when added to the moldable nuxture, but rather gelate and then dry out to form a bonding matrix, it is within the scope of the present invention to add water soluble or water-dispersable polyu,.,.;~l~ units to the moldable mixture which will thereafter polymerize rn situ over tirne. The rate of the POIJI~ .atiUII reaction can be regulated by adjusting the i of the mixture and/or adding a catalyst or rnhibitor. Examples of p(tl~"~ units which may be added to a moldable mixture include Cellosi~e and latex forîning monomers.
Wi& regard to gelation, most cellulose-based polymers (such as Tylose3~) will readily gelate in water at room t~ . Others such as many starches will only gelate in water at higher i I ~a. Certain rnodified starches can, however, gelate at room t.. ,.. ~ c. Hence, cellulose-based and modified starch-ba~ed polymer binders are a.lv~,_uua in that a moldable mixture can be formed therefrom at room ~;. N~ , they are generally a;~.fiL~~ more expensive than typical starch-based polymers which must be heated to gelate. A preferred starch-based polymer is National 51-6912, which may be purchased from National Starch. Depending on the desired rheology of the moldable mixture, including where it is desired to affect the viscûsity or yield stress as a function of time or t~ , it may be preferable to add a number of different organic polymer binders to the moldable mixture. Cellulose-based organic polymer bmders will generally impart their maximum rheological affect almost ~ WO9S/21056 ~1 79272 P~

" 'y, while ~Iy"""i,~ binders will stiffen over time and starch-based binders will stiffen as the ~ r of the mixture is increased.
Other admixtures that may be added to directly influence the rheology of the moldable mixture include iicr~ t~ and lubricants. Dispersamts such as sulfonyl-based materials greatly decrease the viscosity and increase the workability of the moldable mixture while keeping the amoumt of water constant. A corollary is that using a dispersant allows for the mclusion of less water while 7 the same level of workability. A preferred plasticizer and lubricant is pul.~ yl~.... glycol.
The amoumt, identity, and particle packing density of the inorgamic aggregate filler carl greatly affect the rheology and wu.~l.;li~y of the moldable mixture. Inorganic aggregates that are porous or have a high specific surface area will tend to absorb more water than nonporous q, " thereby reducing the amouat of water available to lubricate the particles. This results in a stiffer, more viscous mixture. Particle packing density can also have a IlCllI.~lldUU:I impact on the rheology ofthe mixture by ~' the amount of interstitial space which generally must be filled by water, lubricants, organic polymers, or other liquids in order for the mixture to flow.
The ætual particle packing density should be calculated when tl.-f~rTnininF how much water to add to Lhe moldable mixture. The size and . ' ' O~ of the aggregate particles can also affect L~e rheology and flow properties of the moldable mixture to some degree.
In situations where the moldable mixture will be subjected to high pressures, such as extrusion or oLher high pressure molding processes, it may be possible to take advanLageofLheinterplaybetweenLheprinciplesofparticlepackingandwaterdeficiency in order to temporarily increase the wull~l,;li~.y and flowability while CUII.IJIC ,, the mixture. Por purposes of this -r ~ - and the appended claims, the terms "waterdeficiency" or "deficiency of water" shall refer to a moldable mixture in which Lhere is ,.,- 1~. . ..~ water (and other liquids) to fully occupy the interstitial space between the particles. Because of L~is, there is ~ ~iri~nt water to adequately lubricate the particles.
N~ .L.~a, upon applying a pressure that is great enough to t~ ul~uily increase the particle packing density, the amount of interstitial space between the - 35 particles will decrease. Because water is; - ~ and maintams Lhe same volume under pressure, the increased pressure increases the apparent amount of water that is available to lubricate the particles, thereby mcreasing the wu~k~;li~y and flowability of the mixture. After the pressure is removed, usually after the molding process had ended, the aggregate particles will tend to return to their pre-c~ ,ul~ ;u~ density, ~ereby WO9S/21056 ~'L 7~X r ~o~J~
,.: .
increasing the arnount of intérstitial space and creating an intemal pressure. This results in an almost immediate increase in form stability and green strength.
Hydraulically settable inorganic aggregates such as hydraulic cement, gypsum -~ Jl.aL~:, and calcium oxide can be utilized as a water absorption m~r~ m Thesechemically react with the water, thereby reducing the effective level of water vithin the moldable mixture without resorting to heating or drying techniques. Such mâterials can greatly affect the rheology of the moldable mixtures as a function of the extent of hydration, which is a function of time. In addition, it has been found that hydraulic cement increases the cohesive strength of the green moldable mixture and a fresh sheet made therefrom. It is the cohesion that holds the hlUlL, ' lly filled material together so that the sheet can be pulled through the rollers and yet maintain its form umtil dried sufficiently to obtain sufficient strength.
Finally, other solid, . withjn the mixture such as fibers will affect the rheology ofthe mixture in similar fashion to the inorganic aggregates. Certain fibers may absorb water depending on their porosity and swelling capability. In addition, certain fibers can be treated to become ionically charged, which will allow them to chemically interact with ionically charged organic pl..~j,.j7~g~ such as ionic starches. In this way the fibers may affect the rheology of the mixture to some degree.
2. l;'.fl'~rt of CQmponents on F- ' Properties With regard to the final dried or hardened product, some of the properties consid-ered generally desirable to design into the structural matrix of the sheet include high tensile strength (in general or along particular vectors), flexural strength, flexibility, and ability to elongate, deflect or bend. In some cases, it may be desirable to obtain sheets which 5 1 'ly L,UII ' the properties of cc,ll~ iu~l paper or paperboard 3û products. However, in other cases it may be desirable to obtain a structural matrix having properties not obtainable using ordinary wood pulp or other cu..~ iullal paper-making starting materials. These may mclude increased toughness, higher modulus, water resis-tance, or lower buLk density.
In contrast to Cull~l ' ' ' paper or paperboard, in which the properties of the sheets are extremely dependent on the properties of the pulps used, the properties of the "~ filled sheets used in the present invention are ' ~Iy ;".1. ~ L . ,l of the properties of the fibers used in making the sheets. To be sure, using longer, more tlexible fibers will impart more flexibility to the sheet than shorter, stiffer fibers.

~ WO 95/210S6 21 ~ ~ 2 7 ~ r~ 5 HoweYer, properties that are largely pulp-dependent in Cl.JllY~,llliOlic~i papers can be designed into the innr~?--Airslly filled sheet by adjusting the c.. ~ of the nonfibrous ~ t~ ofthe moldable mixture as well as the processimg technique used.Such properties as stiffness, rigidity, surface fmish, porosity, and the like are generaily not dependent on the type of fibers used in the innr~?-~;^s;ly filled sheets.
The flexibility, tensile strength, flexurai strength, or moduius can be tailored to the particular p.. r.. ~ - criteria of the sheet, container, or other object made therefrom by altering the ~ I and relative ~ of the ~ within tile moldable mixture. In some cases, higher tensiie strength may be an important feature.
In others, it may be less significant. Some sheets shouid preferably be more flexible, while others will be stiff. Some will be relatively dense, others will be thicker, lighter, and more insulative. Alhe important thing is to ?~chieve a materiai that has properties r~ for a particuiar use, while remaining cognizant of cost and other practicai production line pA~?~n~t~ While having "too much" or "too littie" of a particuiar property may be . . .. .~ from the standpoint of 1,. r . - - ~ , from a cost stand-point it may be wastefui or inefficient to provide for the particuiar property.
In generai, increasing the amount of org?lnic polymer binder will increase the tensiie and flexurai strength of the finai hardened sheet, wbile aiso greatiy increasmg the flexibility and resiiience of the sheet. Addmg more organic polymer aiso decreases the stiffness ofthe sheet. Simiiarly, increasimg the c- .~ -- of fibers witbin the mixture also increases the tensile strength of the fmai sheet, A ' ~ ~ higher tensile strength fibers, such as ceramic fibers, aithough such fibers are stiffand will yield a relatively stiff hardened sheet. Conversely, adding flexible fibers, such as naturai ceLiuiosic fibers, will grea'dy mcrease the flexibility, as well as the tensile, tear, ?Ind burst strengths ofthe sheet.
Different fibers have greatly varying degrees of kar and burst strength, flexibility, terlsile strength, ability to elongate without breaking, and stiffness. In order to obtain the ~i~ properties of different types of fibers it may be preferable im some cases to combme two or more different kinds of fibers within the moldable mr~re.
It should aiso be understood that certain sheet forming processes, such as extrusion and rolling will tend to orient the fibers in the direction of elongation of the 35 mixture or sheet. This may be ad ~ ~,~ in order to maximize the tensile strength of the sheet in a certain direction. For example, where the sheet will be required to bend along a hinge, it is preferable for the fibers to be oriented im a way so as to more effectively bridge the two sides of the hinge or bend by being oriented p., ' ' to W095121056 '~ 92~ 2 , ~ 5l ~

the fold line. It may be desirable to concentrate more of the fibers in the area of a hinge or where the sheet requires increased toughness and strength.
The type of aggregate can also affect the properties of the final hardened sheet.
Aggregates comprising generally hard, infieAible. small particles such as clay, kaolin, or chalk, will generally result in a smoother sheet having an increased brittleness.
Lightweight aggregates such as perlite or hollow glass spheres result in a sheet having lower density, lower brittleness, and greater insulating ability. Aggregates such as crushed sand, silica, gypsum, or clay are extremely ;II~A~ ;Vc and can greatly reduce the cost of " r ~ a sheet therefrom. Any material with a high specific surface area gives increased drymg sb~inkage amd shrinkage defects. Materials with lowerspecific surface areas are aJv~l~ v~ because they are less sticky, which allows tbe sheet to be processed by lower tc~ Ialulc rollers without sticking.
HyLaul;~,ally settable aggregates such as hydraulic cement, gypsum ll. lll;ll.yl' and calcium oxide may provide small to signific~mt degrees of bindmg within the hardened sheet depending orl tbe amount in which such IIJvlaul;~lly settable aggregates are added. These may mcrease the stiffness and .,v.. ~ strength of the final sheet and, to some degree, the terlsile strength. Hydraulic cement can also decrease the solubility of the sheet im water, thereby mcreasimg the resistance of the sheet to wakr A. ~.,..i-:;....
Finally, other admixtures within the moldable mixtures can add a . . vur...g propertv to the final product, such as by adding rosin and alum to the mixture. These interact to fomm a very water resistant component within the , 'Iy filled matrix.
In the absence of sigruficant quantities of such ~. , uvr~llg agents, water can be used to remoisten the sheet and i . ' y increase the flexibility, bendabilit~v, and elongation before rupture of the sheet, ~ ,ula l~ v.~here the sheet will be formed into another article of Illclu~a~ll c~ such as a container. Of course, wakr can also facilitate the .1.,, ~.1-~;.... of the sheet a~kr it has been discarded. Water resistance can be introduced by treating the sheet surface with a 5-10% w/w starch solution m order to seal the surface porosity.
As a general rule, inr~rg~n~ ly filled sheets that have lower - ...- ~ c of organic polymer binder and fiber will be more rigid, have a bigher insulation abilitv, have lower c ol.~ ,~,,, resist heat damage, have lower tensile strength, and resist water ti~,ulr l~ as they contain more hydraulic cement, the inclusion of which can also increase the ,VIII~.IIC~;~, strength of the fmal product).

WO95121056 I~,l/IJ..,_ 3 2~ 7g2~72 S Sheets that baYe lower ~.~ .. ~.. 1 l.. ~ of organic binder but higher fiber content will have higher tensile strength, have higher toughness, have lower Cu~ JIC,~;vc and flexural strengths, have lower stiffness and higher flexibility, and be fairly resistant to water ~ (p~ as the amount of hydraulic cement is incre sed).
T ~ ~ly filled sheets that have bigher ~ of organic pol,Ymer binder and lower ,~ of fiber will be more water soluble arld rl~-grq~
easier to mold (allowing for the Illo.luL~ Lulc of thinner sheets), have ' '~ high Cull.l~lc~a;~. and tensile strengths, higher toughness, moderate flexibility, and lower stiffness.
Finally, innr~,qnirqlly filled sheets that have higher c ~ of organic polymer binder and fiber will have properties that are most similar to (.UIIV ~ iUII~II papcr, will have highertensile strength, toughness, and folding endurance, have moderately bigh Culll,ulc~:~;ve strength, have verY low resistance to water ~ ;---" will have lower resist nce to heat (~ when ~ 1, ' ., the ignition point of fibers or ~l~c.. I.u~ l;.. i I ofthe binder), and have bigher flexibility and lower stiffness.
~rhe highly innr~,qnirqlly filled sheets formed using the ~ r " described herein will preferably have a tensile strength in the range from about 0.05 MPa to about 70 MPa, and more preferably in the range from about S MPa to about 40 MPa. In addition, the sheets will preferably have a bullc density in the range from about 0.4 g/cm3 to about 2 g/cm3, and more preferably about 0.4 g/cm3 to about 1.5 g/cm3. Whether a sheet will have a density at the lower, : " or higher end of this range will generally depend on the desired ~ criteria for a given usage. In light of the foregoing, the highly ;., - ~ ly filled sheets of the present invention will preferably have a tensile strength to bulk derlsity ratio irl the range from about 2 MPa-cm3/g to about 200 MPa-cm3/g, and more preferably in the range from about 3 MPa-cm3/g to about 50 MPa-cm3/g.
The direction-specific strength properties of the highly , "~ filled sheets used in the present invention should be contrasted with those of paper, which is Icnown to have a strong and wealc direction with regard to tensile and tearing strength. The strong direction in ,ullv~,.lL;ul~l paper is the machine direction, while the wealc direction is the cross-macbine direction. While the ratio of the strengths in the strong and wealc direction is about 3:1 in cullv.,llL;ul~l paper, in the present invention it is about 2:1, and can approach about 1: ~ depending on the particular forming process used. In general, decreasing the differential forrning speed tends to allow the fibers to remairl in a more Rndom ~ qntqtinn WO 95/21056 r~

The term "elongate" as used in the ~ ;. . and appended claims with regard to the highly innrg~nirslly fill~d sheet means that the structural matrix of the sheet is capable of being stretched without rupturing and still have a finished surface. In other words, the innr~ ly filled structural matrix of the sheet is capable of moving or changing shape without rupture by application of a force such as pulling or stretching.
The ability ofthe structural matrix of the sheet to elongate before rupture is measured by an Instron tensile test and a stress strain test.
By optimizing the mix design, it is possible to r ' C a sheet that has a structural matrix capable of elongating up to about 20% when moist before teari:ng or fracturing occurs, and from about 0.5% to 8% in the dry sheet. This is usually ~.. 1~1. ~l.. l by optimizing the amounts of fiber and organic binder within the moldable mixture and resulting matrix. Producing a sheet that has a structural matrix capable of elongating within the specified range can be d~ .. ,...1.1;~'..`.1 by mcluding fibers within the moldable mixture such that the fmal hardened sheet will contain fibers in an amount of up to about 50% by volume. The greater the amoumt of fibers or organic binder added, or the better the matrix to fiber interface, the more elongation that can generally be achieved without rupture of the sheet. In addition, the elongation of a dry sheet can be mcreased by adding steam or moisture to the sheet in the order of up to 10% by weight of the dry weight of the sheet. However, this ~ g temporarily reduces the strength of the sheet until it has been dried out again It should be understood that higher tensile strength, as well as greater elongation, will generally be obtained by increasing the amoumt of fibers within the ;.. ~ ly filled matrix. This can be a~ ~.... ,1,l h .~ by adding more fibers to the moldable mix~re or, ' ~ ~,Iy, by attaching a layer of fibers (such as a sheet of paper) on the surface or v~ithin the interior of a highly; .. ~".. : lly filled sheet, or by combining fibers having varying properties of strength and flexibility.
The term "deflect" as used in the ~ and appended claims with regard to the ~ "y filled sheet means that the sheet hds a structural matrix capable ofbending and rolling v~ithout rupture and change in the finished surface. The ability of the sheet to deflect is measured by measuling the elasticity modulus and the fracture energy of the sheet using means known in the art. As with any material, the bending ability of a sheet Illa~ L~ d according to the present invention is largely dependent upon the thickness of the sheet.
One way to measure deflection without regard to sheet thickness is to define deflection as the relative elongation of one side of the sheet compared to the other side WO 951210S6 r~
21~27~

of the sheet. As a sheet is rolled or bent around an axis, the length of the outer side of the sheet will elongate, while the inner side of the sheet generally will not. A thirmer sheet can be bent a far greater degree even though the relative elongation of the outer side compared to the elongation of the irmer side is about the same as in a thicker sheet which carmot bend nearly as far.
This ability of the sheet to deflect is related to the sheet's ability to be elastic, which is measured by Young's modulus; c..,. ~l ....lly, the optimal mix desigrls for achieving the desired deflection range can be optimized; i 1~ -1 iy of elongation.
N. .., th~ ., during the process of forming the sheet into an a,U,ul ~ ~ ' container or other oyect the bendability of the sheet can be t~ uu~a~;l y increased by ,~., ....: ¢ the sheet. The water is believed to be absorbed by the fibers, water-dispersable organic binder, and the interstices between the aggregate particles. Upon drying the formed sheet, the level of bendability will generally decrease while the toughness and hardness of the sheet will generally increase.
In order to obtain a sheet having the desired properties of strength, bendability, irlsulation, toughness, weight, or other ~ ~ criteria, the thickness of the sheet can be altered by adjusting the space between the rollers, as set forth more fully below.
Depending on the tbickness and desired p 1....,. - ~ criteria, the , and their relative . can be adjusted in order to ~.,, ' a particular sheet thickness. The sheets of the present invention may be designed to have greatly varying ~ , however, most products requiring a thin-walled rnaterial will generally use sheets having a thickness in the range from about 0 01 mm to about 3 mm. ~ ,lu~
in ~ where insulation ability or higher strength or stiffness is more important,the sheet thickrless may range up to about I cm.
The preferred thickness of the sheets of the present invention will vary depending on the intended use of the ~ lly filled sheet, container, or object made therefrom. As a matter of example only, where high ~i n ~ y is desired, a thinner sheet will generally be preferred. Conversely, where strength, durâbility, and/or insulation and not ~ n 1 l ..I ~y are the overriding concerns, a thicker sheet will generally be preferred.
- 35 N. .~.ll.~ l.,i.~, where it is desired to bend the sheets along a score, or at least roll them into containers, the innrgr~; ~9l1y filled sheets will preferably have a thickness in the range from about 0.05 mm tû about 2 mm or more, and more preferably in the range from about O.IS rnm to about I mm.

W0 95/2l0s6 ~ 2 . 68 Another aspect of the present invention is the ability of the extruded and rolled material to have high green strength. This is achieved by adjusting the quantity and/or identity of the water-dispersable organic binder that is added to the moldable mixture, as well as the amount of the water. Although adding a relatively low amount of water initially will greatly increase the green strength of the molded material, it is possible amd often desirable to include a higher amount of water initially because it will increas~ the ~vu~ y and the ability of certain molding processes described herein to quickly remove excess water through the application of heat.
As discussed more fully below, the moldable mixture is usually passed through aseriesofheatedrollerswhichdriveoffasigluficantamountofwaterandaidinmolding a sheet with high green strength. N. ~ , one skilled in the art may adjust the water content so that the moldable mixture has an appropriate rheology so that it will be easily and effectively extruded through a particular die, and yet have sufficient form stability such that the mteErity of the sheet is maintained as it is passed through a series of rollers during other processes.
As previously discussed, the moldable mixture is lll;~ 'Iy engineered to have certain desired properties, both as to the mixture itself, as well as the final hardened product. ('~ " it is important to accurately meter the amoumt of material that is added during any batch or continuous admixing of the .
The currently preferred ~ for preparing an ~ "., moldable mixture in an industrial setting is equipment in which the materials ;~ ~ "l" . . .l into the moldable mixture are alltr~m~tir~lly and f ~ metered, mixed (or kneaded), de-aired, and extruded by an auger extruder apparatus. It is also possible to premix some of the ~ in a vessel, as needed, and pump the premixed --r ' into a hl~rlill~l,Ah,g apparatus.
A double shaft sigma blade Icneadmg mixer with an auger for extrusion is the preferred type of mixer. T~e mixer may be adjusted to have different RPMs and, therefore, different shear for different C ~ t~ Typically, the moldable mixtures will be mixed for a maximum of about 10 minutes, and thereafter emptied from the mixer by extrusion for a maximum of about 3 minutes.
The various component materials that are combined within the moldable mixtures used m the present invention are readily available and may be purchasedill~ in bulk quantities. They may be shipped and stored in bags, bms, or train cars, and later moved or unloaded using ~ tiollal means known in the art. In ~ WO 95/21056 21~ ~ 2 7 ~ r~ s~ .

addition, the materials can be stored in large storage silos and then withdrawn amd transported by means of conveyors to the mixing site.
- In certain . ;.. "~ it may be desirable to mix some of the ~.. "l.v.. .
together in a high shear mixer m order to form a more well dispersed, 1..,,,,.~" . v ~
mixture. For example, certain fibers may require such mixing in order to fully ~ 5g71 or break apart from each other. High shear mixing results m a more uniformly blended mixture, which improves the CUIL~ of the ... ,1 ~- ....1 moldable mixture as well as increasing the strength of the final hardened sheet. This is because high shear mixing more uniformly disperses the fiber, aggregate particles, and binder throughout the mixture, thereby creating a more 1-.. ~ .. v - structural matrix within the hardened sheets.
Different mixers are capable of imparting differing shear to the moldable mixer.For example, a kneader imparts higher shear compared to a normal cement mixer, but is low compared to an Eirich Intensive Mixer or a twin auger food extruder.
It should be understood however, tbat high shear, high speed mixing should not be used with materials that have a tendency to break down or .I; :.. t. C,,. ' umder such conditions. Certain lightweight aggregates, such as perlite or hollow glass spheres, will have a tendency to shatter or crush under high shear conditions. In addition, high shear mixing by propeller is generally efficacious only where the mixture has relatively low viscosity. ln those cases where it is desirable to obt~sin a more cohesive, plastic-like mixture, it may be desirable to blend some of the ingrrAi~-nt~, mcluding water, in the high shear mixer and thereatter increase the ~ of~solids, such as fibers or aggregates, using a lower shear kneadmg mixer.
High shear mixing is especially useful where it is desired to i.l~,ull small, _~' ' air voids by adding an air entraining agent witbin the moldable mixture.
In those cases where a hydraulically settable material, such as hydraulic cement or c~slcium oxide has been added to the mixture, it may be ~lv _ to flood the atmosphere above the high shear mixer with carbon dioxide im order to cause the carbon dioxide to react with the mixture. It has been found that carbon dioxide can mcrease the foam stability of a c . ~ mixture and cause an early false setting of hydraulic 35 cement. Carbon dioxide also reacts with calcium oxide in order to create calcium carbonate as an insoluble binding precipitate.
High shear mixers useful in creating the more 1~ . -- v~ mixtures as described herein are disclosed and claimed in U.S. Patent No. 4,æ5,247 entitled "Mixing ~snd Agitating Device"; U.S. Patent No. 4,552,463 entitled "Method and App.7ratus for WO95121056 ~ 9~

Producing a Colloidal Mixture"; U.S. Patent No. 4,88g,428 entitled "Rotary Mill"; U.S.
Patent No. 4,944,595 entitled "Apparatus for Producing Cement Building Material"; and U.S.PatentNo.5,061,319entitled"ProcessforProducingCementBuildingMaterial."
For purposes of disclosure, the foregoing patents are ~u~ d herein by specificreference. High shear mixers within the scope of these patents are aYailable from E.
Khashûggi Industries of Santa Barbara, California, the Assignee of the present invention.
B. F Sheets f - r~ r Once the moldable mixture has been properly blended, it is then transported to the sheet forming apparatus, which will typically comprise an extruder and/or a set or series of rollers. In some cases an apparatus capable of both mixing and extruding the moldable mixture may be used in order to streamline the operation and minimize the ;- -, of the various ~ r ' witbin the system.
Reference is now made to Figure 14, which illustrates a currently preferred system for . - -- .- - ~ sheets from a moldable mixture. The system mcludes a mixing apparatus 150, an auger extruder 160, reduction rollers 171, drying rollers 172, optional rollers 174, optional second drying rollers 178, optional calender finishing rollers 180, and optional spooler 182.
In the first currently preferred sheet forming step, the moldable mixture can beformed into sheets of precise thickness by first extruding the material through an appropriate extruder die and then passmg the extruded material through one or more pairs of reduction rollers as shown in Figure 14.
Figure 15 is an enlarged view of auger extruder 160 shown in the system of Figure 14. Auger extruder 160 includes a feeder 161 tbat feeds the moldable mixture into a first interior chamber 162 within extruder 160. Wlthin the first interior chamber 162 is a first auger screw 163 that exerts forward pressure on and advances the moldable mixture tbrough the first interior chamber 162 toward an evacuation chamber 164.Typically, a negative pressure or vacuum will be applied to evacuation chamber 164 in order to remove unwanted air voids within the moldable mixture.
Thereafter, the moldable mixture will be fed into a second irlterior chamber 165.
A second auger screw 166 will advance the mixture toward a die head 167 having a trar~
verse slit 168 with a die width 169 amd a die thickness 170. The cross-sectional shape - . of transverse slit 168 is coufigured to create a sheet of a desired width and thickness that will generally correspond to die width 169 and die thickness 170.

wo 95121056 2 1 7 9 2 7 ~ P

An important advantage of using an auger extruder is that it allows for a continuous extrusion process. In addition, an auger extruder has the ability to remove unwanted ~ .,lua~,v~, air voids within the moldable mixture. Failure to remove unwanted air voids can result in the sheet having a defective or ~ ,....,- b. ~
struc~ l matrix. During subsequent drying steps, ~ ukuly where relatively high heat is used, unwanted air pockets can greatly expand and cause air bubble defects. However, such defects will generally not occur in the case where finely divided air voids are ihlcull ' within the llr~' " 'ly settable mixture.
Removal of the air voids may be ~c ~ ;i using l,Lll~.,llLiLllal venting means known in the extrusion art as shown in Figure 15, wherein the mixture is first passed into an evacuation chamber 164 by first auger screw 163, and then extruded through the extruder die head 167 by means of second auger screw 166. Alternatively, the unwanted air voids may be removed from the mixture by a process known as "venting" wherem the excess air collects under pressure within the interior chamber and escapes from the extruder by passing through the space defined by the walls of the interior chaunber and the outer edges of the auger screw.
Although the preferred width and thickness of the die will depend upon the widthand thickness of the particular sheet to be r ' cd, the thickness of the extruded sheet will usually be at least twice, and sometime many times, the thickness of the final calendered sheet. The amount of reduction (and, CUIIC~!UIILI;II~SIY~ the thickness multiplier) will depend upon the properties of the sheet in question. Because the reduction process helps control fiber ~-ri,-ntotir.~, the arnount of reduction will often correspond to the degree of desired ~ In addition, the greater the thickness reduction, the greater the elongation of the sheet. In a typical ~ _ process an extruded sheet with a thickness of about 6 mm may be calendered to a sheet with a thickness between about 0.2 mm and about 0.5 mm. Because this is a 12 to 30 folddecrease in thickness, the sheet should cullc ~ elongate 12 to 30 times its original length after extrusion.
- Although the die slit is generally .~ l y shaped, it may contain areas of increased thickness along its width in order to form an extruded sheet having varying thickness along its width. In this case, if rollers are used in c . j - l;.. with the extrusion process they will preferably have ~ecesses or gap variations that correspond to the areas of increased thickness within the extruded sheet. In this way a sheet having reinforced areas of increased strength and stiffness can be produced.

WO 9~1210S6 72 S Ie vill be appreciated that ~vhere the differential between the roller nip and the sheet thickness before the sheet passes between the reduction rollers is small, the fiber orienting flow of material will tend to be localized at or near the sheet surface, with the interior not being subjected to fiber orienting flow. This allows for the production of sheets that have significant ~ or l -;- ~ _1 orientation of fibers at or near the surface of the sheet and more rsndom orientation of fibers within the interior of the sheet. However, by decreasing the nip relative to the initial sheet thickness it is possible to increase the orientation of the fibers within the interior of the sheet by increasing the fiber orienting flow of material within the sheet interior.
In an alternative ....I .o.l;,.... ,1 the width of the die slit can be selectively varied as a function of time as the mixture is extruded through the slit. This permits the extrusion of a sheet having varying thickness along the length of the sheet. In this scenario, it will generslly be necessary to provide rollers that also have varying gap distances as a function of time. However, because of the greater difficulty of perfectly ,~.LIul~lgtherollersto r~~~~~~~ ' ' therateofextrusionofsheetsofvaryingthick-ness along the length thereof, this option is less preferable than creating a sheet with varying thickness along the width as described above.
In addition to nanow die slits to form flat sheets, otber dies may be used to form other objects or shapes. The only criterion being that the extruded shape be capable of being thereafter for~ned rnto a sheet. For example, in some csses it may not be desirable to extrude an extremely wide sheet. Instead, a pipe may be extruded and .. ,1;.. ., .~1 cut and unfolded using a knife located just outside the die head.
The amount of pressure that is applied in order to extrude the moldable mixture will generslly depend on the pressure needed to force the mixture through the die head, as well as the desired rate of extrusion. It should be understood that the rate of extrusion must be csrefully controlled in order for the rate of sheet formation to correspond to the speed at which the sheet is ~ ly passed through the rollers during the ~
step. If the rate of extrusion is too high, excess ~ ly filled material will tend to build up behind the rollers, which will eventually cause a clogging of the system.
Conversely, if the rate of extrusion is too low, the rollers will tend to stretch the extruded sheet, which can result in a fractured or uneven structural matrix, or worse, breakage or tearing of the sheet. The latter can also result in a complete breakdown of the continuous sheet forming process.
It will be understood that an important factor which deterrnines the optimum speed or rate of extrusion is the final thickness of the sheet. A thicker sheet contains ~ wo 9sl2~0s6 2 1 7 3 2 7 ~
more material ~nd will require a higher rate of eAYtrusion to provide the necessary material. Conversely, a thinner sheet contains less material and will require a lower rate of extrusion in order to provide the necessary material.
The ability of the moldable mixture to be extruded through a die head, as, well aS the rate at which it is extruded, is generally a function of the rheology of the mixture, as well as the operating par_meters and properties of the machinery. Factors such as the amount of water, water-dispersable organic binder, dispersant, the particle pæking density, or the level of water absorption by the mixture ~---1, all affect the rheological properties of the mixture.
Because it will sometimes not be possible to control all of the variables that can affect the rate of exttusion, it may be preferable to have an integrated system of trans-ducers which measure the rate of extrusion, or which can detect any buildup of excess rnaterial behind the rollers. This;, . r~ l' ' can then be fed into a computer processor which can then send signals to the extruder in order to adjust the pressure and rate of extrusion in order to fine tune the overall system. A properly integrated system will also be capable of monitoring and adjusting the roller speed as well.
As set forth above, adequate pressure is necessary in order to temporarily increase tbe ~, ' ' ' ~ of the moldable mixture in the case where the mixture has a deficiency of water and has a degree of particle pækmg ~ In a mixture that is water deficient, the spaces (or interstices) between the particles contain A~water to lubricate the particles in order to create adequate workability under ordinary conditions.
As the mixture is , ,~ within the extruder, the cu ~ ....;V~ forces push the particles together, thereby reducing the interstitial space between the particles amd increasing the apparcnt amount of water that is available to lubricate the particles. In this way, w. ' ' ' ~J is increased umtil the mixture has been extluded through the die head, at which point the reduced pressure causes the mixture to exhibit am almost immediate incrcase in stiffness and green strength, which is generally desirable.
It should be understood that the pressure exerted on the moldable mixture during the extrusion process should not be so great so as to crush or fracture the Lt IIL~ . . ,,' t, lower strength aggregates (such as perlite, hollow glass spheres, putnice, or exfoliated rock). Crusbing or otherwise destroying the sttuctural mtegrity of these or similar lightweight aggregates containing a large amount of voids will decrease their insulating effect by ~ the voids. ~ LII~ I~ s, because perlite, exfoliated rock, or other such matenals are relatively ill~ iv~, some leYel of crushing or fractu~ g of the wo 95121056 ~ 2 ~ 2 A ~ J.. S 1 aggregate particles is acceptable. At some point, however, excess pressure will eliminate the lightweight and/or insulative effect of the lightweight aggregate, at which point it would be more ~rnnnmjrsl to simply include a less expensive aggregate such as sand.
In light of each of the factors listed above, the amount of pressure that will be applied by the extruder in order to extrude the moldable mixture will preferably be in the range from about 50 kPa to about 70 MPa, more preferably in the r. nge from about 150 kPa to about 30 MPa, and most preferably in the range from about 350 kPa to about 3.5 MPa.
In some cases, u~li.,ul~l~ where a lower density, higher insulating sheet is desired, it may be all;VOll D_UII~ to employ a blowing agent within the moldable mixture, which is added to the mixture prior to the extrusion process.
It will be understood that the extrusion of the moldable mixture through the diehead will tend to, ' lly orient the individual fibers within the moldable mixture along the "Y" axis, or m the lengthwise direction of the extruded sheet. As will be seen herein below, the ' ' _ process will further orient the fibers in the "Y" direction as the sheet is further elongated during the reduction process. In addition, by employing rollers having varymg gap distances m the "Z" direction (such as conical rollers) some of the fibers cam also be oriented m the "X" direction, i.e., along the width of the sheet.
Thus, it is possible to create a sheet by extrusion, coupled with ' ' ~ which will have ' ' ~c~iul~dlly oriented fibers.
C. Thel' ' ' r In most ' ' of the present invention, it will be preferable to "calender"
the extruded sheet by passmg the sheet between at least one pair of rollers, the purpose of which is ~o improve the uniformity amd surface quality of the sheet. In some ~ the calendering step will only reduce the thickness of the sheet by a small amoumt, if at all. In cases where it is desirable to greatly reduce the thickness of the highly , 'ly filled sheet, it will often be necessary to reduce the thickness of the sheet in steps, wherein the sheet is passed through several pairs of rollers, with each pair having ~uD~c~ y narrower gap distances Ih~,lC~
As the thickness of the sheet is reduced upon passmg through a pair of rollers, it will also elongate in the forward movmg (or "Y") direction. One ~ of sheet elongation is that the fibers will fur~ther be oriented or lined up m the "Y" direction. In this way, the reduction process in ..,.,.1.;..~';.... with the initial extrusion process will create a sheet having ~ h~t~-~tislly IuLidilc-,liullally oriented fibers ir the "Y", or wo ~snl0s6 r~
21~92~`2 lengthwise, direction. However, increasing the speed ofthe ' ' ~ process has been found to create a better ,.- ,fL "..; ~ of fibers throughout the sheet.
Another way to maintain the random orientation of fibers within the sheet is to decrease the differential forming speed of the rollers. That is, where the moldable mixture is fed between the extruding rollers under lower pressures, the sudden increase in rnachirle-direction velocity and ~ g shear as the mixture passes between the rollers will tend to orient the fibers in the machine direction. However, by increasing the pressure of the mixture it is possible to decrease the level of machine-direction shear, thereby resulting in a sheet with a more ~ 1 fiber nripnfS~tinn Another ~ of sheet elongation is that the sheet will "speed up" as it passes between a pair of reduction rollers. The ~ of this is that the roller speed will be "faster" relative to the speed of the sheet as it enters into the rollers. By way of example, if the sheet thickness is reduced by 50% and assuming there is no widening of the sheet during the reduction process the sheet will elongate to twice its origin~q length. This ...., .. q.. ~ 1~ to a doubling of the sheet's velocity before it enters the rollers compared to when it exits the rollers.
The sheet "speeds up" while passing between apair of rollers by being squeezed or pressed into a thi~mer sheet by the rotating rollers. This process of squeezing or pressing the sheet, as well as the speed differential between the entering sheet and the rollers, can create varying shearing forces on the sheet. The apphcation of an eA~ .ly large shearing force can disrupt the integrity of the structural matrix of the sheet and create flaws within the sheet, thereby weakening the sheet. N~.... Ihcl~ it has been found that for mix designs having very low adhesion to the rollers, and which are highly plastic, it may be possible to reduce the extruded sheet to the fmal thickness in just one step using a pair of relatively large diameter rollers.
The diarnder of each of the rollers should be optimized depending on the properties of the rnoldable mixture and the amount of thickness reduction of the;"", ~;,,.,:. ,lly filled sheets. When optimizing the dia~neter of the rollers two competing interests sbould be cn~ PrPd The first relates to the fact that smaller diameter rollers tend to impart a greater amount of shearing force mto the sheet as the sheet passes ~5 between the rollers. This is because the downward angle of culu~ ;ull onto the sheet is on average greater than when using a larger diameter roller.
The use of larger diameter rollers has the drawback of the i -, ~ 1y filled material coming into contact with the roller for a greater period of time, thereby resulting irl an increase in drying of the sheet dunng the ' ' ,, process in the case where the wo 95~21056 r ~79272 : 76 rollers are heated to p}event adhesion. Since more of the sheet comes into contact with a larger diameter roller, heating is even more important when using larger diameter rollers to prevent adhesion. While some drying is a.l~ Lb~uua, drying the sheet too quickly during the ' ' ~ process could result in the illLIvdu~Liull of fractures and other flaws within the structural matrix. A drier sheet is less able to conform to a new shape without a rupture in the matrix than a wetter sheet subjected to the same level of shearing forces.
~ .,.,~..I- ..lly, from this perspective the use of smaller diameter rollers is a.l. . _ for reducing the drying effect of the reduction rollers. N~ a~ some of the drawbacks of using a larger diameter roller can be minimized by using a highly polished roller, lower r. .. ~ , and appropriate mix desigrls to reduce the stickiness of the moldable mixture. Also, passing the sheet through the rollers faster reduces the drymg effect of the rollers and causes greater widening of the sheet.
In light of this, the diameter of the rollers should preferably be optimized and be sufilciently small to prevent overdrymg of the material during the ' ' _ process, wbile also being sufficiently large to reduce the arnount of shearing force imparted to the sheet, thereby allowing a greater reduction of sheet thickness during each reduction step.
The .,~.l;... -:;.... ofthe roller diameters irl order to achieve the greatest amount of reduction of sheet thickness, while at the same time preventing overdrying of the molded sheet, is preferred in order to reduce the nurnber of reduction steps in the , . . - - .. . r . I . . . i. .p process. Besides reducing the number of working parts, reducing the number of reduction steps also eliminates a number of rollers whose speed must be carefully ~ uu~ in order to prevent sheet buildup behind the rollers (in the case of rollers rotating too slow) or sheet tearing (in the case of rollers rotating too fast).
Because each of the roller pairs reduces the thickness of the sheet as it passes3û Lh. .eb~ h. the sheet will speed up each time it passes through a set of rollers.
Therefore, each of the roller pairs must ' r ~ ''y rotate at the proper speed in order to prevent ill~llUU~iUII of the calendering process. ~.1 _ the number of reduction steps greatly simplifies this i,~ ' Ulll~iUII problem.
It is preferable to treat the roller surfaces in order to prevent sticking or adhesion of the innrg,q~irqlly filled sheet to the rollers. One method entails heating the rollers, which causes some of the water within the moldable mixture to evaporate, therebycreating a skam barrier between the sheet and the rollers. E~ v~liu~ of some of the water also reduces the amount of water within the moldable mixture, thereby increasing the green strength of the sheet. The ~ of the rollers, however, must not be so wo ssnlos6 r~

high as to dry or harden the surface of the sheet to the point which would create residual stresses, fractures, flaking, or other .1. ~.. 1;. ~ or illc~ul~iLi.s in the sheet.
Accordingly, it is preferable to heat the rollers to a t~ -r in the range from about 400C to about 1400C, more preferably from sbout 500C to about 120C, amd most preferably from about 600C to about 85 C.
In addition, the rate of drying of the sheet can be reduced by ;~
aggregates having a low specific surface area. Aggregates that haYe a greater specific surface area can more readily release any water that is absorbed within the aggregate, or adsorbed onto the surface, compared to aggregates having a lower specific surface area.
Generally, the stickiness of the moldable mixture increases as the amount of water in the mixture is increased. Therefore, the rollers should generally be heated to a higher t~ 1c.L~ in cases where the mixture contams more water in order to prevent sticking, which is a.;va.lt~.,uu~ because sheets containing a higher water content must generally have more of the water removed in order to obtain adequate green strength.
Because heated rollers can drive off sigluficant amoumtS of water and improve the form stability, the amount of acceptable sheet thickness reduction will generally decrease im each successive reduction step as the sheet becomes drier. This is because a drier, stiffer sheet can tolerate less shear before flaws are introduced mto the structural matrix.
In an alternative ~ 1, adhesion between the im~rg,s~irs11y filled sheets and rollers can be reduced by cooling the rollers to or below room ~ r Heating the mixture in the extruder to a relatively high 1. '1" -' ~, for example, and then cooling the sheet surface causes the vaporizing water to condense, which is thought to create a thin film of water between the sheet and the roller. The rollers should be cool enough to prevent the surface of the sheet from adhering to the rollers, but not so cold to cause the ~0 sheet to freeze or become so stiff or inflexible that it will fracture or shatter during the .. ~. 1.. ~ process. Accordingly, it is preferable to cool the rollers to a t I ~. r in the range from about 0C to about 40C, more preferably from about 5C to about 35C, andmostpreferablyfromabout 10Ctoabout 15C.
In order to obtain the beneficial llu~ , effects of cooling the rollers, it willgenerally be necessary to frst heat the moldable mixture before or during the extrusion process to a ~ 1 r that is ~;L"~ y higher than the t 111~ t~c of tbe cooled . . rollers. This allows for the beneficial ~ ;-- of water vapor from the heated miviture onto the cooled rollers, thereby creating a thin layer of lubricating water between the rollers and the moldable mixture. ~ , it will generally be preferable to heat WO95/21056 ~ ~ ~ 9 2 7 2 S the extruding mixture to a r~ C in the range from about 20DC to about 80C. The t~ allu~ will correlate with the tc~ u~ uc ofthe rollers.
Another way to reduce the level of adhesion between the rollers and the innrE?~ ly filled sheet is to treat the roller surfaces in order to make them less amenable to adhesion. Rollers are typically made from polished stainless steel and coated with a nonstick material such as polished chrome, nickel, or tefion.
By varying the gap between the rollers, it is possible to cause the .... " y~ lly filled sheet to spread or widen in the "X" direction from the pomt where the gap is more narrow toward fhe point whae the gap is wider. Spreading or widening the sheet in the "X" direction also has the beneficial effect of reorienting some of the fibers in the "X"
direction, thereby creating a sheet with ~- ' c~,liul~lly oriented fibers (in the "X" and "Y"
directions). Orienting the fibers maximizes the tensile strength impaTting properties of the fibers in the direction of fiber nri-~r~f-lfinn In addition, orienting the fibers is particularly useful in order to rcinforce a hinge or score within the sheet. Fibers that are greater in length than the width of the fold or bend can act as a bridge to connect the material on either side of the fold or bend even if the matrix is partially or even ~ lly fractured along the fold or bend. This bridging effect is enhanced if the fibers are generally aligned at an angle to the fold or bend.
Finally, it should be understood that due to the plastic nature and relatively higb level of ~ull~b;lil~ of the moldable mixture, the '- .~ , process will usually not result in mucb . . . of the sheet. In other words, the density of the sheet will remain ~al~ult;all~ constant throughout the f ' ' process, although some compaction would be expected, r " ~ 1~ where the sheet has b~cn S;~;~url~y driedwhile passmg between the reduction rollers. Where: , iâ desired, the sheet can be passed between a pair of ~ . rollers 174, as shown in Figure 14, following a drying step as set forth more fully below.
One of ordinary skill m the art will appreciate that the extrusion step need notformally employ the use of an "extruder" æ the term is used in the art. The purpose of the extrusion step is to provide a , well-regulated supply of moldable ;.. ~ filledmaterialtotherolle~s. Thismaybeachievedbyother" l, ,:~ ~
known to those skilled in the aTt to effect the "extrusion" or flow of material through an a~J~lu~l;dtc opening. The force needed to cause a moldable mixture to flow may, for exarnple, be supplied by gravity.

~ wo 95121056 ~! ~ 7 g 2 7 ~ r~

D. The rL Proce~s Although the . ,~ ."~ process often results in partial or even substantial drying of the molded jnnrg,orlirolly filled sheet, it will be preferable to further drv the sheet in order to obtain a sheet with the desired properties of tensile strength and toughness. Of course, the sheet ~vill naturally dry out over time, although it may be unfeasible to wait for the sheet to naturally air dry. Accelerated drying may bel ,. d in a number of ways, each of which involves heating the sheet in order to drive off the excess water. A preferred method of drying the sheet involves the use of large diameter, heated drying rollers sometimes known in the art as "Yankee" rollers, although a series of smaller rollers may also be employed. The main concern is that the combined surface areas of the rollers be adequate to efficiently effectuate drying of the sheet.
In contrast to the reduction rollers, which are generally aligned in pairs of rollers, the drying rollers are ....1. v ' ".y aligned so that the sheet passes over the surface of each roller individually in sequence. In this way, the two sides of the highly innr~?n~ ly filled sheet are ' ~ dried in steps. While the sheet passes between the reduction rollers during the ' ' ~, step in a generally linear path, the sheet follows a ~enerally sinusoidal path when wrapping around and through the drying rollers during the drying step.
Figure 14 shows drying rollers 172, with the side of sheet 155 adjacent to the first drying roller heated by the first drying roller while the other side is exposed to the air. The heated sheet loses water in the form of vapor, which c?n escape out the sides of the roller or the surface of the sheet opposite the roller. The vapor also provides a nonstick barrier between the sheet and roller. The drying rollers may have tiny holes in the surface thereof in order to allow some of the water vapor to escape through the holes during the drying step.
As sheet 155 continues on its path it is rolled onto a second drying roller where the other side of sheet 155 comes into contact with the roller surface and is dried (Figure 14). This process may be continued for as many steps as needed in order to dry the sheet in the desired amount. The amoumt of drying will depend on a number offactors, including the a mount of water witbin the sheet, the thickness of the sheet, the time that the sheet is in contact with the roller surface, the t .lA~ of the rollers, and the desired properties of the sheet. In some cases it may be preferable to dry one side of the sheet more ~ = the other. This may be ~ by designing a system which wo sst2l0s6 ~ 3 2 rt 2 r~l~u~

maximizes the contact of one side of the sheet with the drying rollers while . ;the contact of the other side.
The ~ -r of the drying rollers will depend on a number of factors, including the moisture content of the sheet as it passes over a particular roller. In any event, the ~..~ ,aLlllc of the drying rollers should be less than about 3000C. Although the moldable i.. ~ ,r ." lly filled material should not be heated to above 250C m order to prevent the destruction of the organic ~ (such as the organic poly~ner binderor cellulosic fibers), rollers heated to above this ~ . ,. r may be used so long as there is adequate water within the mixture to cool the material as the water vaporizes.
N~ V~LII"I~ ..." as the amount of water decreases during the drying process, theof the rollers should be reduced to prevent ~, . ~.ll~i;ll~; of the material.
In some cases, it may be preferable to use a drying tunnel or chamber m c ~ ; . with the drying rollers. In order to obtain the full effect of heat convection drying, it is often preferable to circulate the heated air in order to speed up the drying process. The l. 'l~ ..l. -G within the drying tunnel, as well as the residence or dwell time of the sheet within the tunnel, will determine the amount and rate of ~ val~u~ ll of the water within the innr~:~nirolly filled material.
In order to achieve quick drying of the surface, it may be preferable to more quickly pass the sheet through a very hot drying tunnel. Conversely, in order to achieve a more uniform and deep drying of the sheet, h might be desirable to pass the sheet more slowly through the drying tunnel. The drying tunnel should not usually exceed 250C
m order to prevent the destruction of cellulose fibers and the organic polymer binder. In light ofthe foregomg, the drying tunnel will prefGrably be heated to a ~ ~G in the range from about 50C to about 2500C, and more preferably in the range from about 100C to about 200C.
In some cases, the drying process set forth above will be the final step before the sheet is either used to form a container or other object or, ' ~,~ly, rolled onto a spool or stacked as sheets until needed. In other cases, IJ~ Li.,.~ ly where a sheet with a smoother, more paper-like finish is desired, this drying step will be followed by one or more additional steps set forth more fully below, including a ~ step andlor a finishing step.
In the case of ~ . it is generally preferable to leave the sheets with adequate moisture so that the i ~ rg,o ~:~ally f lled matrix remains in a moldable condition to prevent fracturing of the matrix during the optional ~ ;- , step. O~erwise, if the drying step is not followed by a ~ ;- step, it is generally desired to sl~hrto~tiolly WO 9S/21056 % 1 7 ~ ~ ~ 2 r~

dry out the sheet in order to quickly maximize the tensile strength and toughness of the sheet.
.
E. C~ ' ' Fi ' er Pr~r~cc.~c In many cases, it may be desirable to compact the ~ r~ni~ Ally filled sheet in order to achieve the final thiclcness, tolerance, and surface finish. In addition, the process can be used to remove unwanted voids within the structural matrix.
Refernng to Figure 14, sheet 155 may be optionally passed between a pair of C ~
rollers 174 after being aubakullidll~y dried by drying rollers 172. The ~ , process generally yields a sheet with higher density and strength, fewer surfæe defects, a reduced thickness, and also fixes and aligns the compacted particles within the sheet surface. The amount of CUIII~ , force of the u~ . rollers should be adjusted to correspond to the particular properties of the sheet.
The ~ , process preferably yields a sheet of reduced tbiclcness and increased density without causing significant elongation of the sheet and witnout negatively disrupting or weakening the structural matrix. In order to achieve c.. Au without elongating the sneet and without wealcening the structural matrix, it is important to control Lhe drying process so that the sheet contains an ~IJlVlJlk.~, amount of water to maintam a moldable rheology of the sheet. If Lhe sheet contains too much water, the rollers will elongate the sheet in similar fashion as Lhe reduction rollers. In facL the; . rollers are auba~L~lly the same as the reduction rollers. The only difference is that r~-n~r ~ir~n rather than elongation will occur if Lhe sheet is dry enough amd the reduction in sheet thickness is less than the total porosity left by the (,~ UI~lLiOII
of Lhe water (i e., if the ~ . ~r ' of water creates an additional porosity of 25% then the roller nip should be at least 75% of the thickness of the ~.. , I sheet).
On the other hand, overdrymg the sheet prior to the . , - step can yield a weaker sheeL At some point Lhe ;~ AII.Y filled sheet can become so dry and brittle that the ;~ .AI'.y filled matrix is no longer moldable and cannot be c.,."l,.~
- without fracturing. The stressing of the strucbllal matrix c~m diminish Lhe final strength amd other beneficial properties of the sheet even if the fractures are IlU~.IU~ U~U;~, and not Yisible to the naked eye. The ;. " ,~ II,y filled matrix should preferably be just moist enough to allow it to flow or mold out the voids when compacted, but dry enough so that cnmF ~ n not elongation, occurs. N~ , even a completely dry sheet may be compacted m some cæs wiLhout ;~ u~ significant defects by first ~ the sheet.

wo 95121056 2 ~ ~ ~ 2 7 ~ I .,.......................................... . . ~

It has been found preferable to compact and dry the sheets in a sequential fashion in order to ~l u~ ,ly compact the sheet. This allows for the removal of just enough of the water tû allûw the sheet to compact, while retaining sufficient water to maintain the moldability ofthe inorg,on~ ly filled matrix. Because the cnmr^ ~ti~n process forces the particles into closer proximity, thereby increasing the particle paclcing density and reducing the porosity within the sheet, there is more water available for lubricating the particles after the ÇI mrorti--n step, assuming a constant water content, within the sheet.
This allows for the ' or subsequent removal of water from the sheet without a significant reduction in moldability. This in turn malces possible the sequential , and removal of water withûut ~...- -- .... l -- -' damage to the sheet structure.
Because the ~ process (including ûne or more ~ Jl-- . steps) usually involves a slightly moist sheet, it is usually preferable after the c~ ;.... step to further dry the sheet in a manner similar to the drying process outlined above using optional drying rollers 178 as shown in Figure 14. This optional drying step may be carried out using drying rollers 178, a drying tulmel, or a .. l. -.-~;.. of the two.
N~ .k,~ " in some cases the sheet may be further processed without a second drying step, such as where the sheet is ' 1~, used to form a container or other object, is scored, or where it is ûtherwise a 1~ . _ to have a slightly mûist sheet.
It may also be preferable to further alter the surface ûf the in~lr~nirolly filled sheet by passing the sheet between one or more pairs of finishing rollers 180 as shown in Figure 14. For example, in order tû create a sheet with a very smooth surface on one or both sides, the sheet may be passed between a pair of hard amd soft rollers. The term "hard roller" refers to a roller having a very polished surface and which leaves the side of the sheet in contact with the hard roller very smooth. The term "soft roller" refers to a roller having a surface capable of creating enough friction between the soft roller and the sheet that it pulls the sheet through the hard amd soft roller pair. This is necessary because the hard roller is usually too slick to pull the dry sheet through a pair of hard rollers. Besides, some slippage of the hard roller is ~lv in order to align the particles on the surface ofthe sheet. Using a driven, highly polished hard roller in order to " , ' ' " the sheet results in a sheet having a very smûoth surface finish. The finishing process may be optionally facilitated by spraying water on the sheet surface, and/or by coating the surface with clay, calcium carbonate, or other .I,U,UIUI ' ' coating materials known to one of ordinary skill in the art.
In other ,...l ....l;... . ~ finishing rollers 180 can impart a desired texture such as a meshed or checkered surface. Instead of using a hard and a soft roller, rollers which WO 9S/21056 ~ ~ 7 ~ 2 7 2 r~

S can imprint the sheets with the desired finish may be used. If desired, the rollers can imprint the surface of the sheet with a logo or other design. Speciad rollers capable of imparting a water mark can be used done or in ~ with any of these other rollers.
Although the finishing or ' ' ~ process usudly requires some rAn~rArtinn of a sheet that has been dried to the point where the inrr~nir~lly filled matrix is no longer moldable, the ~ I is not so great that it S;~;lflr~ ly weakens the sheet and is generdly localized at the surface of the sheet. The tradeoff between the slight reduction in sheet strength is the vast ihlllJlU._III.,II~ in surface qudity that is brought about by the firlisbing process.
The inA,r~anirAAIly filled sheets may d.~ be creped much like ~u~v~ ;ul~d paper in order to provide a highly extensible sheet that is capable of absorbing energy at sudden rates of strain. Creped sheets are ill~lC~;II~ ' import_nt in the production of shipping sacks. G,l.~ iul~l creping is performed either at the wet press section of a paper machine (wet crepe) or on a Yankee dryer (dry crepe). Although the exact parameters of either a wet or dry creping process will differ between the r.r~ ~ -lly filled sheets of the present invention and tree paper, one of ordinary skill in the art will recognize how to adjust the creping process in order to obtain creped filled sheets.
It has been found that the , 'ly filled sheets can be treated with strong acids in order to parchment the fibrous surface portion of the sheet matrix. Treating the sheet with, for ex_mple, _- ' sulfiJric acid causes the cellulosic fibers to swell l.c.... i.. -'y and become partially dissolved. In this state, the plastici~ed fibers close their pores, fill in ~ voids and achieve more intimate contact between them for more extensive hydrogen bonding. Rinsing with water causes 1.~ :u ~ and network ~.. ~.. 1;.1- ;.. resulting in fibers that are stronger wet than dry, lint free, odor free, taste free, and resistant to grease and oils. By combining I 'a naturd tensile toughness with extensibility imparted by wet creping,; ~ filled paper with great shock-absorbing capability can be produced.
In the present invention, it can be seen that the ~ , process would be expected to work better as the fiber content of the sheets is increased. Increased fiber content facilitates the sealing of the pores and increased hydrogen bonding of the fibers.
It should be . A~i~r-A~oo~i however, that certain acid sensitive ~ such as calcium alrbonate, should probably not be used where the sheet is to be ~,_.1..1....~l.

w09512~056 I~.l/L~
2~792~2 ~

F. C~ Processes It may be preferable to apply coatings or coating materials to the highly ;....,~".":. ,.11~ filled sheets prepared æcordmg to the processes set forth above. Coatings can be used to alter the surfæe . ~ of the sheet in a number of ways, including sealing and protecting the sheet or other object made therefrom. Coatings may provide protection against moisture, base, acid, grease, or organic solvents. They may also provide a smoother, glossier, or scuff-resistant surfæe and help to prevent fiber "fly away." Coatings can be used to reinforce the wet i~r~pni-~lly filled sheet during the sheet processing stage, or they may strengthen and reinforce a dry sheet, ~ ' `!/ at a bend or fold line. Some coatings can also be utilized as æhesives or to form laminated sheets.
Related to the concept of coating is the "sizing" of the sheets, which essentially refers to the sealing of the pores of the sheets. Sizing c~m be used to i~nprove the ~ ~nu~l and water resistance of the in~rgi~ni~ ly filled sheets. Sizing can either mcrease or decrease the strength, modulus, and elongation (or ~Ah~ y) depending on their ~ - ~ and amount used. Some sizings or coatings may soften the ;"", .~;"": .1- ~ filled matrix, thereby resulting irl a more flexible sheet. Other sizings may maAe the sheet more stiff.
Coatings can be applied to the surface of the sheet during the sheet forming process, in which case the process is an "u.. ~9~ ;n~ process. However, it may be preferable to apply tbe coating after the sheet fomling process, m which case the process is an "off^machine" process.
The intent of the coating process is usually to achieve a unifomm film with minimum defects on the surface of the sheet. The sdection of a particular coating process depends on a number of substrate (ie., sheet) variables, as well as coating li., ". ,l -;.. variables. The substrate variables mclude tbe strengtb, wettability, porosity, density, ! '' , and uniformity of the sheet. The coating rl..., ~l ';.. variables include total solids content, solvent base (including water solubility and volatility), surface tension, and rheology.
Coatings may be applied to the sheets using any coating method known in the art of . ----1'~ paper, paperboard, plastic, pGl~ e~ sheet metal, or other packaging materials. Coating processes known in the art that may be used to coat the 'Iy filled sheets of the present invention include blade, puddle, air-knife, printing, Dahlgren, gravure, and powder coating. Coatings may also be applied byspraying the sheet or other object made therefrom with the coating material or by dipping ~ wo 95/21056 ~ i 7 9 2 7 2 . ~

the sheet or object into a vat containing an appropriate coating material. Finally, coatings may be coextruded along with the sheet in order to integrate the coating process with the extrusion process. A more det"iled description of useful coating processes is set forth in the Ar~ cl. IIùd~ull Technology.
In some cases, it may be preferable for the coating to be ~I_ t. ,.. ;., fi~qfnrrr~ql~i q, or waterproo Some coatings may also be used to strengthen places where the , "y filled sheets are to be more severely bent, such as where the sheet has been scored. In such cases, a pliable, possibly ~ 1 ~ . . ;. coating may be preferred. Besides these coatings, any appropriate coating material would work depending on the application involved.
G. C~ PrnrPccPc It may be desirable to apply print or other indicia on the surface of the y filled sheet such as trq.~iPmqrkr~, p}oduct r ' nn container or logos. This can be , ' ' ' using printing means known in the art of printing CUII~. ' ' paper or ,U~I~U~,lbUCII-I products. In addition, the sheets may be embossed or provided with a waterlnark. Because the ~, 'ly filled sheets havea relatively high porosity, the applied ink will tend to dry rapidly. In addition, decals, labels or other indicia can be attached or adhered to the ,, '1~ filled sheet using methods known in the art.
Finally, the h~ lly hardened sheets can be ' 'y used to form containers, printed materials, or other objects, or they may be stored until needed such as, for example, by winding the sheets ontû a spooler 182 as shown in Figure 14, or cutting and stacking individual sheets in a pile.
The ~ filled sheets made according to the processes set forth above can then be fashioned into an endless variety of containers or other useful objects. One p~uLi.,ul~l~ valuable use of these sheets is in the ~ _ of disposable food or beverage containers used in the fast food industry.
VI. E~AMPLl~ OF T~F. PRFFERR~n F.MRODlMFl~Ts The following cxamples are presented in order to more ~,u~ .,;r~ lly teach the method of for~ning sheets, containers, and hinges according to the present mvention. The exarnples include various mix designs, as well as methods for ~ ;"~ sheets, containers, hinges, amd other articles of ..- r I...c having varying properties _nd ~iimPncinnc , wo ssnlos6 217 9 2 7 2 EY~n~ r~ 1-6 Highly innre~nir-~lly filled sheets were prepared from moldable mixtures that included the following ~
10 l~mpl~ Ç~S23 Fiber IYIQ~! Water 6 kg 0.25 kg 0.1 kg 1.8 kg 2 5 kg 0.25 kg 0.1 kg 1.7 kg 3 4kg 0.25 kg 0.1 kg 1.6kg 4 3 kg 0.25 kg 0.1 kg l.S kg IS S 2kg 0.25kg O.lkg 1.4kg 6 I kg 0.25 kg 0.1 kg 1.3 kg The fiber that was used in each of these examples was southern pine. The water, Tylose~ (FL 15002), and fibers were first mixed for 10 mmutes under high shear in a Hobart k.. ~ad~ . Tnereafter, the calcium carbonate was added to the mixture, which was mixed for arl additional 4 minutes under low shear.
The particle packing density of the calcium carbonate in each of these mixtures was about 0.63, and the resulting rnixtures had the following ~ , by volume of the total solids of inorganic aggregate, ~ . ly. 89.7%, 87.9%, 85.3%, 81.3%, 74.4%, and 59.2%. These correspond to the following I _ by weight of the total solids: 94.5%, 935%, 92.0%, 89.6%, 85.1%, and 74.1%. The sheets of Examples 1-6 contained the following amounts of fiber as a percentage by volume of the total solids, .~,.,~Liv~4,. 7.2%, 8.5%, 10.3%, 13.1%, 18.0%, and 28.7%. These amounts would beless if measured in weight ~,. .. _ The moldable mixtures were extruded using a deairing auger extruder through a 30 cm x 0.6 cm die to form continuous sheets having wl.~ -r e ~ of width and thickness. The extruded sheet was then passed between a pair of reduction rollers having a gap distance Lll. .~. h._ cul~ .v.llil.~ to the final thickness of vhe sheet formed. Because calcium carbonate has a low specific surface area these mixtures have a low adh. ,;~ , to the rollers. The sheets formed in these examples had thicknesses of 0.23 rnm, 0.3 mm, 0.38 mm, and 0.5 mm.
As less calcium carbonate was used, the tensile strength, flexibility, and folding endurance of the shect increased. However, adding more calcium carbonate yielded a shect with a smoother surface and easier pl~ ~;liL~ through the rollers, which reduced WO95/21056 f~ 1 7 ~ ~ 7 ~ P l/~
S the amount of intemal defects. Increasing the amourlt of CaCO3 had the effect of decreasing the porosity of the sheet, which ranged from 37.4% to 70.3% by volume of the final dried sheets.
The sheets of Examples 1-6 were score cut when dried using a knife blade cutter to form hinges therein. The score cut had a triarlgular profile and resulted in the material below the score forming the hinges having a thickness of 0.1 mm.
EY~ C 7-12 Highly ;IWI~S~lIU~ filled sheets were prepared from moldable mixtures that irlcluded the following Glass Exam~le CaC03 Fiber Tvlose(l9 Water ~h~r~

7 1.0 kg 0.2 kg 0.1 kg 2.1 kg 0.5 kg

8 1.0 kg 0.3 kg 0.1 kg 2.1 kg 0.5 kg 20 9 I.Okg 0.4kg O.lkg 2.1kg 0.5kg 10 1.0 kg 0.5 kg 0.1 kg 2.1 kg 0.5 kg Il l.Okg 0.6kg O.lkg 2.1kg O.5kg 12 1.0 kg 0.7 kg 0.1 kg 2.1 kg 0.5 kg The fiber that was used im each of these examples was southern pine. The water, Tylose~9 (FL 15002), and fibers were first mixed for 10 minutes in a Hobart kneader-mixer. Thereafter, the calcium carbonate and hollow glass spheres were added to the mixture, which was mixed for arl additional 6 minutes under low shear. The particle packing derlsity of the combined calcium carborlate and hollow glass spheres in each of these mixtures was 0.73, and the resulting mixtures had the followirlg ~J~.,~,.. k~C6 by volume of the total solids of inorganic aggregate, l~ . 88.5%, 85.3%, 82.3%, 79.6%, 77.0%, and 74.5%.
The moldable mixtures were extruded using a deairing auger extruder through a 30 cm x 0.6 cm die to form continuous sheets having ~ , " .. dirnerlsions of width and thickness. The extruded sheet was then passed between a pair of reduction rollers having a gap distance 1~ to the final thickness of the sheet formed. Because calcium carbonate and glass spheres each have a low specific surface area these mixtures have a low a~ .,.. to the rollers. The sheets formed im these examples had ~ - of 0.23 mm, 0.3 mm, 0.38 mm, and 0.5 mm.

wossnlos6 r_"~ S~l -When calcium carbonate particles haYing an aYerage diameter of 35 microns were used (maYimum 100 microns), the resulting sheet had a matte surface. HoweYer, when much smaller particles are used (98% of them being smaller tharl 2 microns), theresulting sheet had a glossy surface.
Increasing the fiber of the sheet increased the tensile strength, flexibility, and folding endurar ce of the final hardened sheets.
The sheets of Examples 7-12 were score cut when dried using a continuous die cutroller to form hinges therein. The score cut was made at a 45O angle to the direction of the fibers in the sheets. The score cut had a triangular profile and resulted in the material below the score forming the hinges haYing a thickness of 0.05 mm.

Eya nnlP 13 Examples 7-12 were repeated in every respect except that 1.0 kg mica was substituted for the calcium carbonate. In all other respects the mixtures were prepared in ' 'Iy the same manner. Mica is a clay-like, l' - ' . ' natural mineral having an average particle si~e of less tban about 10 microns. The particle packing densitY of the combined mica and hollow glass spheres in each of these mixtures was about 0.7, and the resultirlg mixtures had the following l _ by volume of thc total solids of morganic aggregate, lc.,~,.Li~ y. 88.5%, 85.3%, 82.3%, 79.6%, 77.0%, and 74.5%. The plate-like shape of the mica yields sheets having glossier surface fmishes.
F.Yq~ 1 4 The mix design and methods set forth in Exarnple 13 were repeated in every way except that 0.25 kg of southem pine was added to the moldable mixture used to form the im~r~?r ;~qlly filled sheets. The final hardened sheets had a tensile strength of 14.56 MPa, a modulus of 2523 MPa, an elongation of 1.42% before failure in the strongest (machine) direction, and a tensile strength of 6.66 MPa and an elongation before failure of 0.93% in the weak (cross-machine) direction.
FY~rl`q I 5 Examples 7-12 were repeated m every respect except that 1.0 kg kaolin was substituted for the calcium carbonate. In all other respects the mixtures were prepared in 5l~hr~sntiol1y the s_me marmer. Kaolin is essentially a rlaturally occurring clay in which 98% of the particles are smaller than about 2 microns. The particle packing ~ wo gsnlo56 2 ~ 7 9 2 ~ 2 P~,ll. S 't derlsity of the combined kaolin and hollow glass spheres in each of these mixtures was 0.6g, and the resulting mixtures had the following p..~ _ by volume of the totalsolids of inorganic aggregate, ~ ,Li~.,l,~. 88.5%, 85.3%, 82.3%, 79.6%, 77.0%, and 74.5%. The kaolin yielded sheets having a glossy surface firlish.

FY~ 16-21 Highly _ 'Iy filled sheets were prepared from moldable mixtures that included the following ~ - r Fused Cellulose Tylose3~ Glass ~mpl~ Silica . Fiber FL 15002 ~a~ SPheres 16 1.0 kg 0.2 kg 0.1 kg 2.1 kg 0.5 kg 17 1.0 kg 0.3 kg 0.1 kg 2.1 kg 0.5 kg 18 1.0 kg 0.4 kg 0.1 kg 2.1 kg 0.5 kg 20 19 1.0 kg 0.5 kg 0.1 kg 2.1 kg 0.5 kg 1.0 kg 0.6 kg 0.1 kg 2.1 kg 0.5 kg 21 1.0 kg 0.7 kg 0.1 kg 2.1 kg 0.5 kg The f ber that was used in each of these examples was southern pine. The wakr, Tylose~ FL 15002, arld fibers were first mixed for 10 minutes in a Hobart kneader-mixer. Thereafkr7 the fused silica and hollow glass spheres were added to the mixture, which was mixed for an additional 6 minutes umder low shear. The particle packing derlsity of the combined fused silica and hollow glass spheres in each of these mixtures was about 0.73, and the resulting mixtures had the following ~ by volume of the total solids of inorganic aggregate, ~ .Li~ . 88.5%, 85.3%, 82.3%, 79.6%, 77.0%, and 74.5%.
The moldable mixtures were extruded using a deairing auger extruder through a 30 cm x 0.6 cm die to form continuous sheets having c ullc~uulll~.~ dimerlsions of width and thickness. The extruded sheet was then passed between a pair of reduction rollers having a gap distance Ll.~.cl,~ ;"P, to the final thickness of the sheet formed. Fused silica is quartzitic and has am average particle size less than about 10 microns. Because fused silica and glass spheres each have a low specific surface area these mixtures have a low adll..;~ ,a to the rollers. The sheets formed in theseexamples had Llfi.,h.~....~,i. of 0.23 mm, 0.3 mrn, 0.38 mm, and 0.5 mm 21792:

Increasing the fiber of the sheet increased the tensile strength, flexibility, and fo~ding endurance of the final hardened sheets.
The sheets of Examples 16-21 had double score cuts made therein to form hinges that allowed bending of the sheets in either direction~ The score cuts had a triangular profile and were made on both sides of the sheets at adjacent locations.
While Examples 22-29 which follow are h,~uLl.~L;~I m nature, they are based on similar mix designs and processes that have actually been carried out. They are presented in this manner in order to more fully teach the invention.
FY~ C 2~-27 IS Highly ~ '~y filled sheets are prepared from moldable mixtures that include the following c~
Finely Ground Cellulose Tylose~D Glass l~am~ (' ' Fiber FL 15002 Water SDheres 20 æ l.o kg 0.2 kg 0.1 kg 2.1 kg 0.5 kg 23 1.0 kg 0.3 kg 0.1 kg 2.1 kg 0.5 kg 24 1.0 kg 0.4 kg 0.1 kg 2.1 kg O.S kg 25 1.0 kg O.S kg 0.1 kg 2.1 kg 0.5 kg 26 1.0 kg 0.6 kg 0.1 kg 2.1 kg O.S kg 25 27 1.0 kg 0.7 kg 0.1 kg 2.1 kg O.S kg The fiber that is used in each of these examples is from southem pine. The water, Tylose~19 FL 15002, and fibers are first mixed for 10 minutes in a Hobart kneader-mixer.
Thereafter, the finely ground gralute and hollow glass spheres are added to the mixture, which is mixed for an additional 6 minutes under low shear. The particle packing density ofthe combined finely ground grar,ite and hollow glass spheres in each of these mixtures is about 0.73, and the resulting mixtures have the following ~ by volume ofthe total solids of inorganic agg}egate, ~ .,I.y . ~8.5%, 85.3%, 82.3%, 79.6%, 77.0%, and 74.5%
The moldable mixtures are extruded using a deairing auger extruder through a 30 cm x 0.6 cm die to form continuous sheets having ~" ..q....,.l; .,, .l,."..,~;...,~ of width and thickness. The extluded sheet is then passed bet veen a pair of reduction rollers havirig a gap distance IL~.CI~ .I Cullc~ , to the final thickness of the sheet formed. The low specif c surface area of the glass spheres causes these mixtures to have ~7~72 ~ WO 95/21056 r~
S lower a~;h_a~ .vv to the rollers. The sheets formed in these examples have lLIchl~aa~a of 0.23 mm, 0.3 mm, 0.38 mm, amd 0.5 mm.
Increasing the fiber of the sheet increases the tensile strength, flexibility, and folding endurance of the final hardened sheets.
The sheets of Examples 22-27 have double score cuts made therein to form hinges that allow bending of the sheets in either direction. The score cuts have a triamgular profile and are made on both sides of the sheets at adjacent locations.
FY~"~PI~ 28 Examples 22-27 are repeated in every respect except that 1.0 kg of finely groumdquartz is substituted for the finely ground gr~mite. In all other respects the miYtures are prepared in aubaL~Li~ the same manner. The particle pæking density of the combined finely ground quartz and hollow glass spheres in eæh of these mixtures is about 0.74, arld the resulting mixtures have the following 1, ~ t~ - by volume of the total solids of inorganic aggregate, Icv~,~.Li~ . 88.5%, 85.3%, 82.3%, 79.6%, 77.0%, amd 74.5%.
Decreasing the amount of aggregate increases the effective amounts of organic oinder and fibers. Including more aggregate yields sheets that have greater stiffness, are more brittle, and have greater . ~,..v;~., strength. Increasing the amoumt of fiber amd organic binder yields sheets that have greater flexibility, toughness, and tensile strength.
EY~ 29 Examples 22-27 are repeated in every respect except that 1.0 kg finely ground basalt is substituted for the finely ground gramte. In all other respects the mixtures are prepared in ' "~l the same manner. The particle packing derlsity of the combinedfinely ground basalt and hollow glass spheres m eæh of these mixtures is about 0.74, and the resulting mixtures have the following ~ by volume of the total solids of inorganic aggregate, Ic~.,~ . 88.5%, 85.3%, 82.3%, 79.6%, 77.0%, and 74.5%.
Decreasing the amount of aggregate increases the effective amolmts of organic - binder amd fibers. Including more aggregate ,vields sheets that have greater stiffness, are more brittle, and have greater WIII~JlCvv;~ strength. Increasing the amoumt of fiber and orgaric binder yields sheets that have greater flexibility, toughness, and tensile strength.
FY~ 30 34 Highly ill~,lL, 'Iy filled sheets were prepared from moldable mixtures that include the followlng ~----r wo 95/21056 ~ 1 7 ~ Z 7 2 P~l/lJ~. . . ~

s Glass E~l~ CaC03 Fiber IYIQ~ Water ~iRhÇ~
1.0 kB 0.2 kg 0.1 kg 2.1 kg 0.0 kg 31 1.0 kg 0.2 kg 0.1 kg 2.1 kg 0.5 kg 10 32 I.Okg 0.2 kg 0.1 kg 2.1 kg 1.0 kg 33 1.0 kg 0.2 kg 0.1 kg 2.1 kg 1.5 kg 34 I.Okg 0.2kg 0.1 kg 2.1 kg 2.0kg The fiber that was used in each of these examples was southern pine. The water, Tylose~ (FL 15002), and fibers were first mixed for 10 minutes in a Hobart kneader-mixer. Thereafter, the calcium carbonate and hollow glass spheres were added to the mixture, which was mixed for an additional 6 minutes umder low shear. The particle packing density of the combined calcium carbonate and hollow glass spheres in eæh of these mixtures was about 0.73, and the resulting mixtures had the following p~
by volume of the total solids of inorganic aggregate, ~ l), . 62.8%, g8.5%, 93 .2%, 95.2%, and 96 6%. The densities (expressed as g/cm3) of the resulting sheets were 2.0, 0.87, 0.66, 0.57, and 0.52, .~
The moldable mixtures were extruded usmg a deairing auger extruder through a 30 cm x 0.6 cm die to form continuous sheets having ~UllCi r '' ,, dimensions of width and thickness. The extruded sheets were then passed bet~veen a pair of reduction rollers having a gap distance Ih~ h Cull~ ,uulld;ll~ to the fmal thickness of the sheetsformed. Because calcium carbonate and glass spheres each have a low specific surface area these mixtures had a low ' ~.II.,aa to the rollers. The sheets formed in these examples had ~ ~ of 0.23 mm, 0.3 mm, 0.38 mm, and 0.5 mm.
The sheets of Examples 30-34 were pressed while wet with a scoring die and fiexed to form living hinges therein. The pressed scores had a rounded profile and were made at a 35O angle to the directiûn of the fibers in the sheets. The scores were pressed at a controlled rate, depth and pressure such that the material below the scores forming the hinges had a thickness of 0.1 mm.
FY~ 35 Relatively thin i~lvly,a~P~lly filled sheets were formed by molding an inorga-nically filled mixture which included the following:

~792~2 wO 95121056 Water 2.0 kg Tylose~) FL 15002 0.2 kg Hollow Glass Spheres (<100 microns) 2.0 kg Abaca Fiber 5% by volume of total solids The innrg~ni~ lly filled mixture was made by prewetting the abaca fiber (which is pretreated by the r ' 50 that greater than 85% of the cellulose is a-lu~ ,llulGa~) and then adding the excess water and the fibers to a mixture of Tylose~. This mixture was mixed at relatively high speed for about 10 minutes, and then at a relatively slow speed for 10 minutes after the hollow glass spheres were added.
This mixture was passed between a pair of rollers amd formed into sheets having a thickness of about I rnm. Wet sheets were scored and then folded in an attempt to create a box. A fair amount of splitting resulted and a box with sufficient strength amd integrity generally could not be formed.
Thereafter, sheets were first allowed to harden and then scored, folded into theshape of a bo!~, and glued together by cementing or gluing methods well-known in the paper art. The amount of splitting at the fold was negligible, .~ that it is preferable to score and then fold the thin sheets after they have been allowed to harden or solidify somewhat. The thin sheets were formed irlto a box that had the shape, look and weight of a dry cereal box r ' ~;id presently from paperboard stock.
In the following examples, very thin sheets are formed (0.1-0.5 mm) which have many ~ and properties which make them suitable for use much like paper, /.,lbU~lld, plastic, pol~aL~ or metal sheets of similar thickness amd weight. The desired properties are designed into the sheets using a ~ ,.... ;..g approach. This allows for the r ' C of sheets having a variety of desirable properties, mcluding properties not generally possible using mass-produced sheet-like objects presently r ' ~;d from the foregoing materials.
r ~ 36-51 r. 'ly filled sheets capable of being formed into a variety of objects (including food or beverage containers) are ", ~ I from moldable mixtures made according to Examples 1-6.
In order to obtain sheets havmg the desired thickness, the extruded sheets are reduced in steps by using reduction roller pairs having IJ-u~ ly smaller gap dLstances between ~e roller.,. The sheet 11~ are reduced as follows:

Wo 95/21056 217 9 2 72 r~
6 mm ~ 2 mm ~ 0.5 mm => final thickness (0.45 mm, 0.4 mm, 0.35 mm, 0.3 mm, 0.25 mm, or 0.2 mm) A ~ . ", .1. - ' ;.... of the extn~sion process and the rolling process yields sheets with Si~ rl~al.tly . ~ y oriented fibers along the length (or machine direction) of the sheet. Because of tbis, the sheets have higher tensile strength in the machine direc-tion compared to the cross-machine direction. This fætor can be utilized in order to maximize the y... '.. -- ~ of the container in the direction in ~vhich tensile strength is more important.
The hardened . .. ~,,.. :. ~lly filled sheets are finished, coated, and then formed into a number of different food and beverage containers. For example, a "clamshell"
container (such as those presently used in the fast food industty to package 1 - .1.... ,~,.. ~) is made by cutting an appropriate blank from a sheet, score cutting the blank to form the desired fold lines, foldulg the blank into the shape of a clamshell container, and adhering the ends of the folded blanL (using both adhesive and ;~t' .If~. L~ g flap means) to preserve the integrity of the container. Sheets having thicknesses of OA mm and 0.5 mm are used to make the clamshell containers. The sheet bends or closes together on the side of the sheet opposite the score cut. It should be noted that normal scores m Wll~ ~Itiullal materials generally allow the sheet to more easily bend or close together on the side of the score. The clamshell containers exhibit ~ y -l l or superior insulating ability compared to paper clamshells.
A french fry coDtainer (such as those used to serve cooked french fries in the fast food industty) is made by cutting an appropriate blank from a sheet, score cutting the blank to form the desired fold lines, folding the blank into the shape of a french fry container, and a&ermg the ends of the folded blank using adhesive means to preserve the integrity of the container. Sheets having tbicknesses of 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, and 0.5 mm are used to make the french fry containers.
A frozen food box (such as those used by . ' to package frozen foods such as vegetables or french fries) is made by cutting an ayylul blank from a sheet, score cutting the blank to form the desired fold lines, folding the blank into the shape of a frozen food box, and adhering the ends of the folded blarlk using adhesive means to preserve the integrity of the box. Sheets having ILl~hl~ of 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, and 0.5 mm are used to make the frozen food boxes.

wo gsnlos6 217 9 2 7 2 r~ . D
9s S A cold cereal box is made by cutting an ~ blank from a 0.3 mm thick sheet, score cutting the blank to form the desired fold lines, folding the blar~k into the shape of a cold cereal box, and adhering the ends of the folded blank. using a&esive means to preserve the integrity of the cereal box.
A straw is made by rolling a piece of a 0.25 mm sheet mto the form of a straw and a&ering the ends together using a&esion means known in the art. A hmge is moldedin one section of the straw to make the straw bendable. In making the straw, as in making each of the containers set forth above, it is aJv ~ to control the moisture content of the sheet in order to maintain the highest level of flexibility of the sheet. The higher level of flexibility minimizes splitting and tearing of the sheet.
The containers so made are set forth as follows, including the thickness of the sheet used to make each container:
E~L ~a~ Sl Th;~ kn~
36 clamshell 0.4 mm 37 clamshell 0.5 mm 38 french fry container 0.25 mm 39 french fry container 0.3 mm 40 french fry container 0.35 mm 41 french fry container 0.4 mm 42 french fry container 0.45 mm 43 french fry container 0.5 mm 44 frozen food box 0.25 mm 45 froæn food box 0.3 mm 46 frozen food box 0.35 mm 47 frozen food box 0.4 mm 48 frozen food box 0.45 mm 49 frozen food box 0.5 mm 50 cold cereai box 0.3 mm 51 drinking straw 0.25 mm EY9~1( 52 Examples 36-51 are repeated in every respect except that a highly inrlvgsr~ iy filled mixture having the following ~ is used instead:

wossnlos6 P~.1/L_ 5~ .
2~79272 5 Perlite : 1.0 kg Mica 1.0 kg Fiber (Southerrl pine) 0.25 kg Tylose(lD FL 15002 0.2 kg Water 2.5 kg The mica, fiber, Tylose~, and water are mixed together in a high shear mixer for 5 minutes, after which the perlite is added and the resulting mixture is mixed for an additional 5 minutes in a low shear mixer. The O "y filled miYture is then placed into an auger extruder and eYAtruded through a die having an opening in the shape of a slit.
The miYture is extruded into continuous sheets having a width of 300 mm and a thickness of 6rnm.
The sheets are thereafter passed between one or more pairs of reduction rollers in order to obtain sheets having fmal l;li. h~ of 0.2 mm, 0.25 rnm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, and 0.5 mm, .~
The sheets can be processed into each of the containers set forth above, including a clamshell, french fry container, frozen food box, cold cereal box, and drinking straw.
EYs~rl~ 53 Example 51 is repeated in every respect except that the sheet used to form the drinking straw has a thickness of only 0.05 mm. The drinking straw formed in this example contains a~ 1/5 the mass of the straw that is 0.25 mm thick, making it more suitable for the mass production of disposable, single-use drinking straws.
EYs~rl~ 54 Clamshell containers are made usmg the sheets made according to Examples 36-52. The sheets are tested to deter~nine the optimum score cut depth which will allow for the easiest bend, while at the same time leaving a hinge with the highest strength and resilience. Score depths ranging between 20% to 50% are tested, with a score depth of 25% yielding the best results. In addition, thicker sheets (0.4-0.5 mm) give a better score and yield a stronger, more rigid clamshell container.
EY9~l^ 55 A clamshell is made using the sheets of Examples 36-52, except that a triple reverse hinge is used. That is, a series of three score cuts are cut into the outer side of the WO 951210!;6 I ~
~ 9272 clamshell contamer. Because this decreases the distance that each individual score line has to bend, the resulting hinge can be opened and closed more times without breaking compared to a single score cut hinge.
FYq-~ P 56 Clamshell cont,iners made according to EY~amples 36 and 37 are passed through a Cul~ l waY. coating machine, whereby a uniform layer of waY. is applied to thesurfæe. The layer of waY. completely seals the surface of the container to moisture amd renders it watertight.
EYq~lP 57 Clamshell containers made according to EYamples 36 and 37 are made from sheets that are pretreated with starch. This has the effect of greatly reducing the absorption of water by the containers, although over time they will be water ~Pgr EYq~lP 5i Clamshell containers made according to EYarnples 36 and 37 are coated with am acrylic coating usmg a fine spraying nozzle. As does the waY. m EYample 56, the layer of acrylic coatirlg completely seals the surface of tbe container to moisture and renders it watertight. However, the acrylic coatirlg has the advarltage that it is not as visible as the waY. coating. Because a thinner acrylic coating is possible, the container looks almost as if it were uncoated. The glossmess of the container cam be controlled by usrng different types of acrylic coatings.
EYq~lP 59 Clamshell containers made according to Examples 36 and 37 are coated with a ~".. , ~11~ used melamine coatmg using a flne spraying nozzle. As in Examples 56and 58, the layer ûf melamine coating completely seals the surface of the container to moisture and renders it watertight. However, the melamine coating is also less visible and cqn be applied in a thinner coat compared to the wax coating. The glossiness of the container can be controlled by using different types of melamine coatings.
FYqmRI~ 60 Clamshell containers made according to EYamples 36 and 37 are coated with a tOtally~ benigncoatingconsistingûfamixb3reofllJ~Lu~lll~ cllulose WO95/21056 2~ ~927,~

'i plasticized with POIJ~ glycol. This coating completely seals the surface of the container to moisture and renders it watertight. However, the surfæe looks even more natural and less glossy than containers coated with wax, acrylic, or melamine.
FY9rq~nI~ 61 Clamshell containers made according to EY~mples 36 and 37 are coated with a totally ~ ;l. 'Iy benign coating consisting of polylactic acid. This coating completely seals the surface of the container to moisture and renders it watertight.

FY~ 62 Clamshell containers made according to EY~amples 36 and 37 are coated with a totally ~ h~ 'Iy benign coating consisting of soy bean protein. This coating completely seals the surface of the container to moisture and renders it watertight.
FY~,nl~ 63-69 French fry containers made according to EYamples 38 13 are .llt~ / coated with the same coating materials used to coat the clamshell containers in EY mples 56-62.
The results are substantially identical to those achieved with the coated clamshell 25 containers.
('A ii~pr'' ' 63 wa,Y~
64 starch 30 65 acrylic 66 melamine 67 plasticized IIJ~U~ .~ ,llulose 68 polylactic acid 69 soy bean protein FY~ 70-76 Froæn food boxes made according to Examples 44-49 are alt~ coated with the same coating materials used to coat the clamshell containers in Examples 56-62.

WO 95/21056 P~
21~2~2 gg S The results are ~--h~ ti51lly identical to those achieved with the coated clamshell containers.
~2iam~ç ~n~tir~
wax 71 starch 72 acrylic 73 melamine 74 plasticized lly~u~J~ ,cllulose 75 polylactic acid 76 soybcanprotein FY~plPq 77-83 Cold ccreal boxes made according to Example 50 were ' ~ coated with the same coating materials used to coat the clamshell containers in Examples 56-62. The results are substantially identical to those achievcd with the coated clamshdl containers.
~ Cn~
77 wax 7g starch 79 acrylic 80 melamine 81 plasticized LJLu~ lu.,llulose 82 polylactic acid 83 soy bean protein F~ e 84-90 - Drinking straws made accûrding to Example 51 are .~ l.dti~ coated with the same coating materials used to coat the clamshell containers in EY~amples 56-62. The results are .~,~lt;ally identical to those achieved with the coated clamshell containers with regard to the outcr surface of the straws, although it is more difficult to adequately coat the inside of the straw in this manncr.

WO 95/21056 ' r~ Ji'~

5 ~ Ç. C~ ;~ M~P.i~l 84 wax starch 86 acrylic 87 melamine 88 plasticizedll~ui!ylll. Lh~l~cllulose 89 polylactic acid soy bean protem 1~Y~ P 91 The containers set forth above are placed in a microwave oven and tested for microwave ~... ,l,-:;l,;l;ly, that is, they are tested to determine whether the containers themselves, or the food items within them, become hot when a container and food are exposed to microwave radiation. In fact, the containers themselves will remain cool.
Because of the low dielectric constant of the material, all of the energy goes mto the food, not the container.
For the same reason, steam may condense onto the surface of the container during theirlitialstagesofthel~ u.. ~andquicklyrevaporizeunderfi~ther~ "u.. V~
Therefore, when the food container is opened, no condensed steiam is on the surface of the container after the microwave process. Any excess steam comes out when the container is opened, leaving food which looks and tastes better. This is in sharp contrast to ~ol~ l.l . containers which tend to ~ ' large amounts of conderlsed steam on the container surfaces, thereby rendering a "soggy" iand, herlce, less desirable, food product. In addition, I.c,l.~;,l~lc..~, containers often melt if the food is heated too long.
The specific heats ofthe ~ , filled materials are relatively low, and these materials also have a low thermal constant. This allows for less thermal conduction from the food to the container during the microwave process. It is possible, therefore, to remove the container from the rnicrowave oven without burning the hands. After the container is removed from the microwave ûven it slowly warms (by absorbmg some of the heat within the food) but never becomes too hot to touch.
FY~?IP 92 Flat paper sheets suitable for ~ f~ a wide variety of food and beverage containers are ' c~ from an inorganically filled mixture contairing the following:

~ WO95/21056 ~ 272 ~ Cl Perlite 0.6 kg Hollow Glass Spheres (< 0.1 mm) 1.0 kg Mica 1.0 kg Fiber (Southern pine) 0.25 kg Tylose~9 FL 15002 0.2 kg Water 2.5 kg The mica, fiber, Tylose(l9, and water are mixed together in a high shear mixer for 5 minutes, after which the perlite and hollow glass spheres are added and the resulting mixture is mixed using low shear. The mixture is extruded using an auger extruder and a die into a sheet 30 cm wide and 0.6 cm thick. The sheet is passed ~u~ between pairs of heated rollers in order to reduce the thickness of the sheet to between 0.1 mm and 2mm.
The sheets of Example 92 are pressed while wet at a controlled rate, depth, and pressure with a scoring die on both sides thereof in order to form a double score hinge.
The pressed double scores are formed at a 600 angle to the direction of the fibers and have a 1~; ~ ' profile. The formed hinges allow bending of the sheets in either direction.
~Ys~ 93 An ;.. ~ lly filled mixture is made having the following .
Gypsum 1 - J.' ' 1.O kg Perlite 0.5 kg Tylose(E 0.075 kg Fiber 0.25 kg Water 2.6 kg - The gypsum, Tylose(l9, fiber, and water are mixed together in a high shear mixer for 3 minutes, after which the perlite is added and mixed in a low shear mixer for an 3s additional 3 minutes.
The mixture is extruded into a sheet having a thickness of 6 mm and then calendered im order to reduce the thickness of the sheet m steps to yield a sheet having a final thickness ranging between 0.25 mm to 0.5 mm. The sheet is pressed in the wet state on one side thereof with multiple scores having rounded profiles to form a hinge wo 9~ 056 ~ 2 ~ Z r~

therein. These multiple score hinges provide increased bending of the sheets compared to sheets with a single score hinge.
The sheet is readily fommed into food or beverage containers using any appropriate procedure set forth in tbis ;~ ..., The strength properties are ~.,. 1.,..,.l.l~ to containers made usmg other mixtures and may be useful in the place of, e.g, paper, paperboard,or~ol~ c~ containers.
FY9~19 94 Any of the ~ lly filled mix designs set forth irl the above examples is altered to include about 25% gypsum 1~ by weight of the aggregate. The gypsum acts as a water absorbing component (or intemal drying agent) and results in quicker fomm stability. The strength properties of containers fommed therefrom are ' '~ to mixtures not including gypsum.
r ss Any of the innrg~ irslly filled mix designs set forth in the above exarnples is altered to include about 25% portland cement by weight of the aggregate. The portland cement acts as a water absorbing component (or intemal dlying agent) and results in quicker fomm stability. In addition, the portland cement improves the mtemal c~,ll~,;,;~.,~ of the moldable mixture, which irnproves the workability and fomm stability of the mixture. The portland cement improves the strength and increases the stiffness of the final hardened product. The por'dand cement also reduces the flexibility of the product to some degree.
EY~.rU?If~ 96 Highly ;, . .. ~;,.. . '~ y filled sheets were prepared and then coated with am external sizing to determme the effect, if any, on the strength and other properties of the sheets.
The sheets were formed by extruding, and then passmg between a pair of rollers, a moldable mixture containing the following:
Calcium Carbonate 1.0 kg Hollow Glass Spheres 0.5 kg Southern Pine Flbers 0.4 kg Tylose~9 FL 15002 0.4 kg Water 2.1 kg WO 95121056 ~ 2 7 2 r~

A hardened sheet (Sheet 1) fommed therefrom amd having a thickness of I mm had a tensile strength of 18.48 MPa, a modulus of 1863 MPa, and an elongation before failure of 2.42%. Sheet I was then "sized" (or coated in order to seal the pores of the sheet) using an aqueous starch solution. The resulting sized sheet had a tensile strength of 21.83 MPa, a modulus of 2198 MPa, and an elongation before failure of 2.02%. This shows that a starch sizing increases the tensile strength and stiffness of am ~ 'Iy filled sheet.
A second hardened sheet formed from the above moldable mixture (Sheet 2) was found to have a tensile strength of 21.21 MPa, a modulus of 2120 MPa, and an elongation before failure of 3.22%. Sheet 2 was then sized using am aqueous latex-kaolin sizing (70% loading). The sized sheet had a tensile strength of 18.59 MPa, a modulus of 3305 MPa, and an elongation before failure of 2.13%. This shows that a latex-kaolin sizing decreases the tensile strength while increasing the stiffness of an i-nr~7.n;~ ~lly filled sheet. This coating reduced the water absorption of the sheet to a more significant degree than the starch coating.
Another of Sheet 2 was instead sized usmg a latex-kaolm-starch (70% loading) sizing. The sized sheet had a tensile strength of 15.31 MPa, a modulus of 3954 MPa, and an elongation before failure of 1.28%. This shows that a kaolim-latex-starch sizing decreases the tensile strength while imcreasing the stiffness of am; . .. ~ filled sheet to a greater degree than a latex-kaolin sizing.
A third hardened sheet formed from the above moldable mixture (Sheet 3) was foundtohaveatensilestrengthofll.ll MPa,amodulusofl380MPa,andanelongation before failure of 1.86%. Sheet 3 was then sized using a latex-kaolin sizing (50%loading), yielding a sized sheet having a tensile strength of 10.78 MPa, a modulus of 2164 MPa, and an elongation before failure of 1.62%. This sizing material slightly decreases the tensile strength while - ' 'y increasing the stiffness of the sheet.
Another of Sheet 3 was instead sized using a latex-kaolin-starch sizing (50%
loading), yielding a sheet having a tensile strength of 10.86 MPa, a modulus of 1934 - MPa, and an elongation before failure of 1.15%. This sizing material slightly decreases the tensile strength while increasing the stiffness of the sheet.
The sheets of Examples 96 are score cut when dry usmg a knife blade cutter to form hinges therein. The score cut has a triangular profile and results im the material below the score forming the hinges having a thickness of 0.1 mm. The hinges allow the sheets to be formed into a variet,v of containers.

WO 95/21056 P~ L ~
2~79272 S Eyqn~l~ 97 Highly , 'ly filled sheets were formed by extruding and then passing between a pair of rollers a moldable mixture having the following ,~ .. ,.l... . ~t~
Specific Gravitv ~hlm~
Calcium Carbonate 0.5 kg 2.5 20%
Southern Pine Fibers 0.5 kg 1.29 38.8%
Tylose~9 FL 15002 0.3 kg 1.22 24.6%
15 Water l.Okg 1.0 !6%
Total Solids 83.4%
The volume of the fibers with respect to the totq-l solids volume was 46.5%. Thesheeb formed m this example were found to have a tensile strength of 56 MPa.
The sheets of Example 97 are pressed while in the wet state with multiple scoreshaving a rectangular profile on one side of the sheets to form a hinge therein. The scorcs are pressed into the sheets at a 200 angle from the direction of the fibers in the sheeb.
The hinges allow the sheeb to be formed into a variety of containers.
The sheets can be rolled onto a spool much like paper and can be used thereaftermuch like paper. For example, the rolled paper is later formed into a variety of objects such as a box, french fry calton, etc. In order to fold the sheet it is preferable to score the sheet first, and then fold the sheet along the score.
E ' 98 The mix design and sheet forming process of Exsrnple 97 are repeated in every ~espect except that some of the calcium carbonate is replaced with calciuln oxide. This creates a binding effect as the calcium oxide is converted to calcium carbonate through the reaction with carbon dioxide and water.
EY ~,~ 99 Waste jnrr~,qnirqlly filled containers were composted along with waste food.
After four weeks, the containers were completely broken down and resulted in compost that ylhctqntiqlly resembled potting soil.

WO 95121056 ~ 1 7 EYS~rl~ 100 Using any of the foregoing ~ set forth in the above examples, an in~rg~nirs~lly filled sheet is formed, scored and then fashioned into the shape of a carton.
Depending on the ~ the carton will exhibit high strength, durability, flexibility, low weight, and/or low density.
~Y5~rl~ 101 Using any of the foregoing ~ set forth in the above examples, am ;.,...~;,... -IIyfilledsheetisformedandthenfashionedintotheshapeofabox. Thismay be carried out by extrusion, and/or ' ' g and/or score cutting, and/or folding.
Depending on the ~ ... the box will exhibit high strength, durability, flexibility, low weight, and/or low density.
~Y~n~rl~ 102 Using any of the foregoing ~ set forth in the above examples, r ~ lly filled sheets are formed, scored to produce hinges therein, and made into food or beverage containers using any Y~ ~r ' ' procedure set forth m this ~; r As more fiber is added, the _ 'Iy filled material has greater flexibility and toughness, which make the material more suitable for making a fold or bend therein. The added fibers make the hardened sheets suitable to make a hinge, such as by scoring the sheets with single, double or multiple scores, which allow the sheets to be bent.
The present invention may be embodied in other specific forms without departing from its spirit or essential 1~ The described i ' " are to be considered in all respects as illustrative only and not restrictive. The scope of the invention is, therefore, mdicated by the appended claims rather th~m by the foregoing ~Ircrrir~ All changes which come within the meaning and range of c . - . . ' y of the claims are to be embraced within their scope.

Claims (46)

1. An article of manufacture comprising a hinged inorganically filled matrixincluding a substantially homogenous mixture of aggregate and organic binder, the matrix being formed from an inorganically filled mixture comprising water, a water-dispersable organic polymer binder selected from the group consisting of a polysaccharide, a protein, and mixtures or derivatives thereof, an inorganic aggregate material having a concentration in a range from about 40% to about 95% by weight of the total solids in the inorganically filled mixture, and a fibrous material substantially homogeneously dispersed throughout the inorganically filled matrix, wherein the inorganically filled matrix has a thickness in a range from about 0.01 mm to about 3 mm, and wherein the inorganically filled matrix degrades after prolonged exposure to water.

2. The article of manufacture of claim 1, wherein the hinged inorganically filled matrix has a thickness in a range from about 0.01 mm to about 1 mm.

3. The article of manufacture of claim 1, wherein the hinged inorganically filled matrix includes a living hinge.

4. The article of manufacture of claim 1, wherein the hinged inorganically filled matrix includes a nonliving hinge.

5. An article of manufacture comprising a hinged inorganically filled matrixincluding a substantially homogenous mixture of aggregate and organic binder, the matrix being formed from an inorganically filled mixture comprising water, a water-dispersable organic polymer binder selected from the group consisting of a polysaccharide, a protein, and mixtures or derivatives thereof, an inorganic aggregate material having a concentration in a range from about 40% to about 98% by volume of the total solids in the inorganically filled mixture, and a fibrous material, the fibrous material being substantially dispersed throughout the inorganically filled matrix, wherein the inorganically filled matrix has a thickness in a range from about 0.01 mm to about 3 mm, and wherein the inorganically filled matrix degrades after prolonged exposure to water.

6. The article of manufacture of claims 1 or 5, wherein the hinged inorganically filled matrix includes a living hinge.

7. The article of manufacture of claims 1 or 5, wherein the hinged inorganically filled matrix includes a nonliving hinge.

8. The article of manufacture of claims 1 or 5, wherein the inorganic aggregate material comprises individual particles that are size optimized in order to achieve a predetermined particle packing density of the aggregate material.

9. The article of manufacture of claim 8, wherein the particle packing density of the aggregate material is at least about 0.65.

10. The article of manufacture of claims 1 or 5, wherein the aggregate material is selected from the group consisting of perlite, vermiculite, hollow glass spheres, porous ceramic spheres, lightweight expanded geologic materials, pumice, clay, gypsum, calcium carbonate, mica, silica, alumina, sand, gravel, sandstone, limestone, and mixtures thereof.

11. The article of manufacture of claims 1 or 5, wherein the polysaccharide is selected from the group consisting of a cellulose-based polymer and a starch-based polymer, and mixtures thereof.

12. The article of manufacture of claim 11, wherein the cellulose-based polymer is selected from the group consisting of methylhydroxyethylcellulose, hydroxy-methylethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, hydroxy-ethylcellulose, hydroxyethylpropylcellulose, and mixtures thereof.

13. The article of manufacture of claim 11, wherein the starch-based polymer is selected from the group consisting of amylopectin, amylose, seagel, starch acetates, starch hydroxyethyl ethers, ionic starches, long-chain alkylstarches, dextrins, amine starches, phosphate starches, dialdehyde starches, and mixtures thereof.

14. The article of manufacture of claim 1 or 5, wherein the protein is selected from the group consisting of a prolamine derived from corn, collagen, casein, and mixtures thereof.

15 . The article of manufacture of claims 1 or 5, wherein the fibrous material is selected from the group consisting of organic fibers, inorganic fibers, and mixtures thereof.

16. The article of manufacture of claim 15, wherein the fibrous material is selected from the group consisting of sunn hemp, cotton, bagasse, abaca, flax, southem pine, southem hardwood fibers, glass fibers, silica fibers, ceramic fibers, carbon fibers, metal fibers, and mixtures thereof.

17. The article of manufacture of claims 1 or 5, wherein the aspect ratio of theindividual fibers within the fibrous material is at least about 10:1.

18. The article of manufacture of claims 1 or 5, wherein the inorganic aggregate material comprises a hydraulically settable material.

19. The article of manufacture of claim 18, wherein the hydraulically settable material is selected from the group consisting of portland grey cement, portland white cement, slag cement, calcium aluminate cement, silicate cement, phosphate cement, high-alumina cement, magnesium oxychloride cement, aggregates coated with microfine cement particles, MDF cement, DSP cement, Pyrament-type cement, Densit-type cement, calcium sulfate hemihydrate, calcium oxide, and mixtures thereof.

20. The article of manufacture of claims 1 or 5, wherein the hinged inorganically filled matrix is readily degradable into environmentally neutral components.

21. The article of manufacture of claims 1 or 5, further comprising a coating material on a surface of the hinged inorganically filled matrix.

22. The article of manufacture of claim 21, wherein the coating material increases the ability of the hinged inorganically filled matrix to resist water penetration.

23. The article of manufacture of claim 21, wherein the coating material comprises a biodegradable material.

24. The article of manufacture of claims 1 or 5, wherein the hinged inorganically filled matrix has a tensile strength in a range from about 0.05 MPa to about 70 MPa.

25. The article of manufacture of claims 1 or 5, wherein the hinged inorganically filled matrix has a bulk density in a range from about 0.4 g/cm3 to about 2 g/cm3.

26. The article of manufacture of claims 1 or 5, wherein the hinged inorganically filled matrix has a tensile strength to bulk density ratio in a range from about 2 MPa-cm3/g to about 200 MPa-cm3/g.

27. The article of manufacturing of claims 1 or 5, wherein the hinged inorganically filled matrix can elongate in a range from about 0.5% to about 8% without completely fracturing when dry.

28. The article of manufacture of claims 1 or 5, wherein the hinged inorganically filled matrix can elongate up to about 20% without completely fracturing when moist.

29. The article of manufacture of claims 1 or 5, wherein the hinged inorganically filled matrix is formed by cutting or pressing a score in the inorganically filled matrix.

30. The article of manufacture of claims 1 or 5, wherein the hinged inorganically filled matrix is formed by molding the inorganically filled mixture.

31. The article of manufacture of claims 1 or 5, wherein the hinged inorganically filled matrix is formed by perforating the inorganically filled matrix.

32. The article of manufacture of claims 1 or 5, wherein the hinged inorganically filled matrix includes finely dispersed air voids.

33. The article of manufacture of claims 1 or 5, wherein the hinged inorganically filled matrix may be bent up to an angle of about 360° without substantially fracturing the hinged inorganically filled matrix.

34. The article of manufacture of claims 1 or 5, wherein the hinged inorganically filled matrix further comprises a pulp-containing material disposed thereon.

35. The article of manufacture of claim 34, wherein the pulp-containing material is a paper strip.

36. An article of manufacture comprising:
(a) a first member;
(b) a second member adjacent to the first member; and (c) means for flexibly joining the first and second members so that the first and second members can be pivotally moved about the joining means relativeto one another, wherein the joining means comprises an inorganically filled structural matrix including a substantially homogenous mixture of aggregate and organic binder, the matrix being formed from an inorganically filled mixture comprising water, a water-dispersable organic polylmer binder selected from the group consisting of a polysaccharide, a protein, and mixtures or derivatives thereof, an inorganic aggregate material having a concentration in a range from about 40% to about 98% by volume of the total solids in the inorganically filledmixture, and a fibrous material, the fibrous material being substantially homogeneously dispersed throughout the inorganically filled matrix, wherein the inorganically filled matrix has a thickness in a range from about 0.01 mm to about 3 mm, and wherein the inorganically filled matrix degrades after prolonged exposure to water.

37. The article of manufacture of claim 36, wherein the first and second members have a mechanical resistance to bending and elongation within a first range and wherein the joining means further comprises an area of reduced mechanical resistance to bending and elongation within a second range that is less than the first range of mechanical resistance.

38. The article of manufacture of claim 36, wherein the first and second members have a thickness within a first range and wherein the joining means further comprises an area of reduced thickness within a second range that is less than the first range of thickness.

39. A container comprising:
(a) a first member;
(b) a second member adjacent to the first member; and (c) means for flexibly joining the first and second members so that the first and second members can be pivotally moved about the joining means relativeto one another between a first position wherein the first and second members arein straight alignment with one another and a plurality of other positions wherein the first and second members form an angle in relation to one another;
wherein the joining means and the first and second members have an inorganicallyfilled structural matrix including a substantially homogenous mixture of aggregate and organic binder, the matrix being formed from an inorganically filled mixture comprising water, a water-dispersable organic polymer binder selected from the group consisting of a polysaccharide, a protein, and mixtures or derivatives thereof, an inorganic aggregate material having a concentration in a range from about 40% to about 98% by volume of the total solids in the inorganically filled mixture, and a fibrous material, the fibrous material being substantially homogenously dispersed throughout the inorganically filled matrix, wherein the inorganically filled matrix has a thickness in a range from about 0.01 mm to about 3 mm, and wherein the inorganically filled matrix degrades after prolonged exposure to water.

40. An inorganically filled sheet that has been scored to produce the hinged inorganically filled matrix defined by claim 1 or 5.

41. A container comprising at least one part that is flexibly attached to a second part with the hinged inorganically filled matrix of claim 1 or 5.

42. The container of claim 42, wherein the container is in the shape of a clamshell container.

43. A method of making a hinged inorganically filled matrix having an inorganically filled structural matrix comprising the steps of:
(a) mixing a water-dispersable organic polymer binder selected from the group consisting of a polysaccharide a protein, and mixtures or derivatives thereof, an inorganic aggregate material having a concentration in a range from about 40% to about 98% by volume of the total solids in the inorganically filledmixture, and a fibrous material, in order to form a moldable mixture;
(b) forming the moldable mixture into a form stable sheet having an inorganically filled structural matrix having a substantially homogenous mixtureof aggregate and organic binder, wherein the fibrous material is substantially homogeneously dispersed throughout the inorganically filled matrix, wherein the sheet has a thickness in a range from about 0.01 mm to about 3 mm, and wherein the inorganically filled matrix degrades after prolonged exposure to water; and (c) scoring the sheet to form a hinged inorganically filled matrix in the inorganically filled structural matrix.

44. A method of manufacturing a bendable sheet having an inorganically filled structural matrix, the method comprising the steps of:
(a) mixing a water-dispersable organic polymer binder selected from the group consisting of a polysaccharide, a protein, and mixtures or derivativesthereof, an inorganic aggregate material having a concentration in a range from about 40% to about 98% by volume of the total solids in the inorganically filledmixture, and a fibrous material, in order to form a moldable mixture;
(b) extruding the moldable mixture through a die;
(c) forming the extruded mixture into a form stable sheet having an inorganically filled structural matrix having a substantially homogenous mixtureof aggregate and organic binder, wherein the fibrous material is substantially homogeneously dispersed throughout the inorganically filled matrix; and (d) hardening the sheet to a significant degree in an accelerated manner in order to quickly increase the yield stress of the inorganically filled structural matrix, the sheet having a thickness in a range from about 0.01 mm to about 3 mm, and wherein the inorganically filled matrix degrades after prolonged exposure to water; and (e) cutting a score into a surface of the sheet or cutting a perforation into the sheet that is substantially dried.

45. A method of manufacturing a bendable sheet having an inorganically filled structural matrix, the method comprising the steps of:
(a) mixing a water-dispersable organic polymer binder selected from the group consisting of a polysaccharide a protein, and mixtures or derivatives thereof, an inorganic aggregate material having a concentration in a range from about 40% to about 98% by volume of the total solids in the inorganically filledmixture, and a fibrous material, the fibrous material being in order to form a moldable mixture;
(b) extruding the moldable mixture through a die;
(c) forming the extruded mixture into a form stable sheet having an inorganically filled structural matrix having a substantially homogenous mixtureof aggregate and organic binder, wherein the fibrous material is substantially homogenously dispersed throughout the inorganically filled matrix, wherein the sheet has a thickness in a range from about 0.01 mm to about 3 mm, and wherein the inorganically filled matrix degrades after prolonged exposure to water; and (d) pressing a score into a surface of the sheet prior to drying.

46. The method of claims 43, 44, or 45, wherein the score or perforation defines a fold line along which the sheet may be bent.