CA2197059A1 - Starch-bound cellular matrix - Google Patents

Abstract

Compositions and methods of manufacturing articles, particularly containers and packaging materials, having a particle packed, highly inorganically filled, cellular matrix (8) are disclosed. Suitable inorganically filled mixtures are prepared by mixing together a starch-based binder, a solvent, inorganic aggregates, and optimal admixtures, e.g., fibers, mold-releasing agents, rheology-modifying agents, plasticizers, coating materials, and dispersants, in the correct proportions to form an article which has the desired performance criteria. The inorganically filled mixtures have a predetermined viscosity and are heated between molds at an elevated temperature and pressure to produce form-stable articles having a desired shape and a selectively controlled cellular structure matrix (8). The molded articles may be placed in a high humidity chamber to obtain the necessary flexibility for their intended use. The articles may be manufactured to have properties substantially similar to articles presently made from conventional materials like paper, paperboard, polystyrene, plastic, or other organic materials. They have special utility in the mass production of containers, particularly food and beverage containers.

Description

WO 96/05254 21 9 7 0 ~ .a, 5.~

~ I

~ RACKGROUND OE Tl~E INVENTION
1. The Ficld of the Invention.
The present invention relates generaily to methods and ~;r...,l...,;l;.,... for ". ",r~ g cellular articles from highly i..u~ dlly filled materials havtng a starch-based binder. More particularly, the present invention relates to methods and 10 ~ ~ ~l lq~ for ;r ~ mass-producing envi.~ , superior containers and other articles prepared by combining particie packed inorganic fillers and a starch-based binder with a solvent and other admixtures to form a mixture having a controliedviscosity. The mixture is positioned between opposing molds where the ~ .aLul~ and pressure are elevated to rapidly form the mixture into a form-stable article having a 15 selectively designed cellular structural matrix. The ~ q" ,~ of the mix~re and the processing paratneters can be selected to produce articles that have desired properties of, e.g., thickness, strffness, flexibility, insulation, toughness, product stability, and strength.
The articles can be produced less eA~ and in a manner that is more c..~ neutral than articles made from co..e~ Liu~iai materials, such as paper, 20 plastic, pul~.yl~,,,., foaml g]ass, or metal.

2. The Relevant Technolon~.
A. Articles of 1\~
Materials such as paper, paperboard, plastic, pol~ly~ , and even metals are 25 presently used in enormous quantity in the ..,r....lL.,Lu.~ of articles such as containers, separators, dividers, Gds, tops, cans, and other packaging materials. Advanced processing and packaging techniques presently allow an enormous variety of liquid and solid goods to be stored, packaged, or shipped in such packaging materials while being protected from harnnful elements.
3û Containers and other packaging materials protect goods from ~llVilu.. l.,lluli infiuences and distribution damage, particularly from chemicai and physicai influences.
Packaging helps protect an enormous variety of goods from gases, moisture, light, IlU~,IUUI~;OIh....l~, vermin, physical shock, crushing forces, vibration, leaking, or spilling.
Some packaging materiais also provide a medium for the 1~ ;U~ of ;"f,. I..A~ .. to 35 the consumer, such as the origin of manufacture, contents, advertising, i....l. u~lio"s, brand n and pricing.

WO 96/05254 r~~
21g~ 9 . . ~ ., ~
: ~ . . 2 Typically. most conrainers and other packaging materiais (including disposable containers) are made from paper, paperboard, plastic. poly~Lylcllc~ glass, or metal materials. Each year, over 100 billion aluminum cans. biiiions of giass bottles, and thousands of tons of paper and plastic are used in storing and dispensing soft drinks, 5 juices, processed foods, grains, beer, and other products. Outside of the food and beverage industry, packaging containers (and especially disposable containers) made from such materials are ubiquitous. Paper-baseù articles made primarily from tree derived wood pulp are aiso u.~.ura~,lu~ed each year in enormous quantities. In the IJnited States alone, a~",.u~i....~t~ 5.5 million tons of paper are consumed each year for packaging 10 purposes, which represents oniy about 15% ofthe totai annuai domestic paper production.

B. The Imn~ct of PaDer. Plastic~ Glass and Metal.
Recently, there has been a debate as to which of the .,v... ~,..iiu.~ai materiais (e.g., paper, paperboard, plastic, pGl~iylc..~" giass, or metal) is most damaging to the 15 ..,~ C~ - iu~ raising Ul~;~llL~dliU...~ have convinced many people to substitute one material for another in order to be more envi u----..,-~Lui]~ "correct.~ The debate often misses the point that each of these materials has its own unique .;.u....,~.~L~l ~.. ' One materiai may appear superior to another when viewed in light of a particular ell~;.u.l~l..,.ltdl problem, while ignoring different, often iarger, 20 problems associated with the supposedly preferred materiai.
Polystyrene products, particularly containers and other packaging materiais, have more recently attracted the ire of e...;.u,.,..~...Ldl groups. While pulyaLylcllG itseif is a relatively inert substance, its ~ urd~Lu- G involves the use of a variety of hazardous chemicals and starting materiais. I T, '~..,.,.i~;i styrene is very reactive, and therefore 25 presents a heaith problem to those who must handle it. Because styrene j5 r cd from benzene (a known mutagen and a probable carcinogen), residual quantities ofbenzene can be found in styrene.
More potentiaily damaging has been the use of ~,llu~ unuul UWliJGII~ (or "CFCs")in the u~uluLIuiulc of "blown" or "expanded" polystyrene prûducts. This is because CFCs 30 have been linked to the destruction of the ozone layer. In the u~luuLcLu~c of foams, including blown l~ul~Ly-~ c, CFCs (which are highiy volatile iiquids) have been used to ~expand" or "blow" the polystyrene into a foamed material, which is then molded into the form of cups, plates, trays, boxes, "clam-sheii" containers, spacers, or packaging materiais.
Even the ulhctitl~tinn of less ''c..v;lulurl~llLhiiy damaging" blowing agents (e.g., HCFCs, 35 pentanes. and CO. with l-~d~uuo~bull ~r,.,ll,;" ~ ) are stiii S;~urlca~ y harmful and their elimination would be beneficial.

WO 96/05254 , ,~ ,~ r~ u~,S.'.

As a result, there has been widespread pressure for companies to stop using r polystyrene products in favor of more ~llvhl ~ safe materials. Some environ-mental groups have favored a temporary retum to the use of more "natural" products, ~L such as paper or other products made firom wood pulp, which are believed to be 1,;. ,ri~ Nc ~ ", LLeh,.. " other .,.,~.. u.. ~ I groups have taken the opposite view in order to. minimize the cutting of trees and depletion of forests.
Although paper products are ostensibly biod., addlJIe and have not been linked to the destruction of the ozone laver, recent studies have shown that the r c cfpaper probably more strongly impacts the ~ than does the n~l.lra.lu~e of I û polystyrene. In fact, the wood pulp and paper industry has been identified as one of the five top 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 as compared to an equivalent pG~ product. Various studies have shown that the eftluent from paper r ' g contains ten to one hundred times the 15 amount of: produced in the ,,.a..ura.,lu, c of pG~ ty~ foarn.
In addition, a by-product of paper r ' _ iS that the ~ vh~ is impacted by dioxin, a hamlful toxin. Dioxin, or more accurately, 2,3,7,8-tetrachloro-dibenzo[b,e][1,4]dioxin, is a highly toxic ~ l, and is extremely dangerous, even in very low quantities. Toxic effects of dioxin in animals and humans include anorexia, 2û severe weight loss, h~ u~dL;~y, I r IJh~l vascular lesions, chloracne, gastric ulcers, pul~hJ.i~v. ia, porphyria, cutanea tarda, and premature death. Most experts in the field believe that dioxin is a carcinogen.
Auother drawback of the ~--~.ura~ c of paper and paperboard is the relatively large amount of energy that is required to produce paper. This mcludes the energy 25 required to process wood pulp to the point that the fibers are sufficiently delignified and frayed that they are essentially self-binding under the principles of web physics. In addition, a large amount of energy is required in order to remove the water within uu..~..i;u..al paper slurries, which contain water in an amount of up to about 99.5% by volume. Because so much water must be removed from paper slurries, it is necessary to 30 literaily suck water out of the slurry even before the drying process is begun. Moreover, much of the water that is sucked out during the dewatering processes is usually discarded into the environment.
The - ~r l ~ processes offomling metal sheets tnto containers (particularly cans made of aluminum and tin), blowing glass bottles, and shaping ceramic containers 35 utiiize high amounts of energy because of the necessity to melt and then separately work and shape the raw metal into an h~klll~d;~ or final product. These high energy and ..... ....... ... ...... : .. ... ..... . ........ .. _ _ . .

w0 96105254 q, '~ 5 n, . ~ 9 ~gl, ~

processing ltl~UilCll..UtD not only utilize valuable energy resources. but they also result in signtficant air, water, and heat poDutlon to the environment. While glass can be recycled, that portion that ends up in landfills is essentially non-degradable. Broken glass shards are very dangerous and cam persist for years.
Some ofthese pollution problems are being addressed; however, the result is the use of more energy, as well as the significant addition to the capital I CUU;l tlll~ for the ~ facilities. l~urther, while significant efforts have been expended in recycling programs, only a portion of the raw material needs come from recycling -- most of the raw materials still come from L~ IJIe resources.
Even paper or paperboard, believed by many to be biud.~ ud/l. ~ can persist for year~, even decades, within landfills where they are shielded from air, light, and water--all of which are required for normal l,;odc~d~,Lion activities. There are reports of telephone books and u. D~ having been lifted from garbage dumps that had been buried for decades. This longevity of paper is further ,- . " ' since it is common to treat, coat, or impregnate paper with various protective materials that further slow or prevent ~
Another problem with paper, paperboard, POI~DL.~U U~e, and plastic is that each of these requires relatively expensive organic starting materials, some of which are ' ', such as the use of petroleum in the r ' C of p~ st~ , and plastic.
Althou~,h trees used in making paper and paperboard are renewable in the strict sense of the word, their large land ItU,UUC.n..l~ and rapid depletion in certain areas ofthe world undermines this notion. Hence, the use of huge amounts of essentially UU.UCII~ estarting materials in making articles therefrom cannot be sustained and is unwise from a long term perspective. Fu. i' c, the processes used to make the packaging stock raw 25 materials (such as paper pulp, styrene, or metal sheets) are very energy intensive, cause major amounts of water and air pollution, and require significant capital, t~lU;I I
In light of the foregoing, the debate should not be directed to which of these materials is more or less harmful to the .,.. vh U~u~ lt~ but rather toward asking: Can we discover or develop an alternative material which will solve most, if not all, of the various 30 cllv~ lula~tal problems associated with each ofthese presently used materials?

C. Alternative Materials Due to the more recent awareness ofthe Llt~ ,n;luus environmental impacts of using paper, paperboard, plastic, polystyrene, and metals for a variety of single-use, mainly 35 disposable, articles such as containers and other packaging materials made therefrom (not wo 961052s4 r~
5 ~ ~
s . .. .
to mention Ihe ever mounting political pressures), there has boen an acute need (long since recognized by those skilled in the art) to find c.l~ hu.u~ L.Il;y sound substitute materials.
One alternative has boen to make the desired articles and containers out of baked, edible sheets. e.g., waftles or pancakes. Although edible sheets can be made into trays, cones, and cups which are easily d .. l.. ,~.1 they pose a number of limitations. Edible shoets are prirnarily made from a mixture of water, flour, and a rising agent. The mixture is baked between heated molds into its desired shape. Fats or oils are added to the mixture to permit removal of the sheet from the baking mold. Oxidation of these fats cause the edible sheets to go rancid. From a mechanical standpoint~ the resulting edible 10 shoets are very brittle and far too fragile to replace most articles made from ..u..~
materials. FuuLh~-..ule, edible shoets are overly sensitive to moisture and can easily mold or decompose prior to or during their intended use.
Attempts have also been made to make articles using organic binders. For example, articles have been made from mixtures of starch, water, and a mold-releasing 15 agent. The starch-based mixtures were baked between heated molds until the starch gelated and set in the desired shape for the articles. The resulting products, however, were found to be cost prohibitive. Slow processing times, expensive equipment, and the relatively high cost of starch compared to UO~ LiUU~ll materials made the articles more expensive than UU..~.ldUUCII articles. Although inorganic fillers have been added to 20 starch-based mixtures in an attempt to cut material cost, mixtures containing any significant portion of fillers were unable to produce structurally stable articles that had fiJnctional mechanical properties.
Fu~ ..u~ ~:, the starch-based articles were found to be very fragile and brittle, giving them limited use. To improve flexibility, the articles were placed in a humidity 25 chamber where the moisture was absorbed by the starch to soften the articles. The moisture absorption, however, took several minutes, a;~luLI,~u~lly slowing down the r.~ n ~ , process. Ful ih~ u~, an additional time-consuming step of applying a coating to the article was required to prevent the moisture from escaping from the article once the article was finished. Attempts at producing organic-based articles have also 30 failed to uu..s;sllilldy produce articles that have a smooth, uniform surface. To disguise the surface defects, the articles have usually been made with a waffled surface.Industry has repeatedly sought to develop hlu,~..d.,..ll~ filled materials for the production of disposable articles that are mass-produced and used in large quantities.
Inorganic materials such as clay, natural minerals, and stone are easily accessed, non-35 depletable, hl~"~y~ a;vc, and .,..~.., - '1~ inert. In spite of economic and t~lv;l~ ' ' pressures, extensive research, and the associated long-felt need, the _ _ _ _ ~ ... . . . . . . ...... . . . .

W096/05254 lE I .~
21~7~

technology simply has nor existed for the economic and feasible production of highly i..JI~ . ' "y fi!led materials which could be substituted for paper. paperboard, plastic, PCI~Y~L~ metal, or other organic-based containers and other articles Significant attempts have been made over many years to fill cu~ duudl paper 5 with inorganic materials. such as kaolin and/or calcium carbonate, although there is a limit (about 20-iS% by volume) to the amount of inorganics that can be in~.ul~ulaLcd into paper products. In addition, there have been attempts to fill certain plastic packaging materials with clay in order to increase the l~ y of the product and improve the ability of the packaging matenal to keep fruits or vegetables stored therein fresh. In 10 addition, inorganic materials are routinely added to adhesives and coatings in order to impart certain properties of color or texture to the final product. Ne. ~,. Lll~,lu~ inorganic materials only comprise a small fraction of the overall material used to make packaging materials or other articles, rather than making up the majority of the material mass.
Attempts to increase the amount of inorganic filler in a polymer matrix have had15 significant adverse affects on the rheology and properties of the binding system, e.g,, loss of strengt4 increased brittleness, etc.
In light of the fact that inorganic materials are typically the most economical and ecological material, what is needed are highly ' ,, ' ".~, filled materials that can replace paper, paperboard, plastic, pul~L~,ne, or metal materials as the material of choice for 2û producing containers and articles currently made therefrom. What is further needed are methods and sn,.~po~ l;n..c for molding an in~ la;~" en~;" ".y safe, organicmaterial that, in relatively small quantities, acts as a sàL;ard.Lu,y binder for the inorganic material.
It would be a further i,..~,.u . . in the art to form the highly ' L ' '~ filled25 mixture having an organic binder into containers and other articles currently made from paper, paperboard, pul,~aiylc~ metal, plastic, or other organic materials.
It would be a significant i.. ~. u . ~ .. in the art if such methods and ~ .. 1 .~.~:l ;. -~ielded highly ;nUIg ' ~, filled articles which had properties similar to or superior to paper, paperboard, polystyrene, plastic, or metal materials.
ll would yet be an i"ll.,u . ~n.~,.. L in the art if the methods and ~ v~ yielded containers and articles that could be I~ UL'd-LUICd with or without being placed in a humidity chamber to obtain the desired 9exibility.
It would be still another advantage in the art if the methods and ~
yielded articles that could be formed without the need to ~ , apply a coating 35 thereto.

. . .

wo 96/052s4 ~ ~ 9 7 ~

~ 7 " , It would be an , u.. in the art if the methods and ~ yielded - articles and containers that could be formed having a smoother. more uniform surface with fewer defects It wou]d alsû be a ~Ic~ duu~ illliJlU.~.U~... in the art if the articles could be 5 formed from existing " , r 1 ; ,g equipment and tecbniques presently used to form articles from paperl paperboard, pul~Ly~L..~" plastic, or other org_r~ic materials.
It would be another h~ u . ~ .. in the art if such methods and ~- .p~ for _ articles did not result in the generation of wastes involved in the c of paper, paperboard, plastic, pul~ .~yl ..,." or metal materials.
It would be yet an dd~ Ut in the art if the methods and "c. ~ ~ yielded articles that contained less water which had to be removed during the ~ g process (as compared to paper ,., . " ,r 1... ;. ~..) in order to shorten the processing time and reduce the initial equipment capital investment.
In addition, it would be a significant i.,.~. u . . in the art if such methods and 15 , . - yielded articles that were readily degradable into substances wbich are commonly found in the earth.
From a practical point of view, it would be a significant hut~u.. if such methods and ~ u~ rnadc possible the ~ c of containers and other articles at a cost that was c~ l or cven superior to existing methods of 20 containers or other articles from paper, paperboard, plastic, polystyrene, or metal.
Specifically, it would be desirable to reduce the energy .~uu;,~,...~.,t~, conserve valuable natu;al resources, and reduce the initial capital investment for making articles having the desirable ~ of .,u...~...iu,.41 materials such as paper, metals, pul~i, plastic, or other organic materials.
From a " ,, perspective, it would be a significant auv~ ,ut in the art of shaping highly h.vlL ~ filled materials if such methods and .
allowed for the mass-production of higbly inorganically filled articles which could rapidly be formed and ready for use within a matter of minutes from the beginning of the, . ...r... s..,-~g process.
It would also be a L,c.,.~,.,duu~ adv~u,.,~,.. ~.lt in the art to provide methods and ,.. ~.o~ which allowed for the production of highly inorganically filled articles having greater flexibility, flexural strength, toughness, moldability, mass-~.. ' ' "~".
product stability, and lower environmental impact compared to Cu..~'uuL;ull~l materials having a high content of inorganic filler.
Such methods and . ~.. ul~u~ are disclosed and claimed herein.

21~059 wos6/0s2s4 .i~ ~ . r~l,u~

SUMMARY QF TnF INVENTION
The present invention discloses novel . ~ " "1'~~ and articles of mal~uL~,lu~i prepared ~rom particle packed, highlv h.o. ~ lly filled materials having a starch-based binder and a IL..uluu~ lu.,~lly controllçd cellular matrix. In addition, the present 5 invention includes novel methods and ~ u, ~ fûr ~ ~, such articles.
Initially, amatenals science and ~IU~IUDIIUI~LUI~I, L,; - ; ir approachisusedto develop an ~y!..u~.. hlu~ t;r~n~ally filled mixture. The ~ ...I.ol 1~ of the mixture and their amounts are selected based on an IIU;I~ " of the iut~ between processing parametçrs and the properties ofthe individual ~ moldable mixture, 10 and final article.
The mixture is designed to produce a final product having the desired propertiesfor its intended use at minimal cost. Properties that can be optimized include thickness, density, modulus of elasticity, ~WI~ DD;~. strength, tensile strength, fiexural strength, rdçxibility, range of strain, thermal r~.p~ itiPc, and specific hçat. Because of the ability 15 to impart or alter these properties as nççded, a wide variety of articles can be made, including cups, trays, cartons, boxes, bottles, crates, and numerous other articles used for, e.g., packaging, storing, shipping, serving, portioning, and dispensing.
The inventive mjxtures can indude a variety of e..~ , safe 'e---r ' .
including a starch-based binder, water, inorganic aggregates, inert organic aggregates, 20 mold-releasing agents, fibers, rheology-modifying agents, cross-Linkers, ~ r plasticizers, and coatings. The mixture is designed with the primary ~Olla;d~ lliu..~ of maximizing the inorganic ~: u~ c~ , minimizing the starch component and solvent, and ~ selectively modifying the viscosity to produce articles quickly, ;II~A~ d~, and having the desired properties for their intended use. The starch-based binder acts as the binding 25 agent and typically includes a starch such as potato starch, corn starch, waxy com starch, rice starch, wheat starch, their grain ~ ;d~_CcDDUl D, e.g., flour and cracked grains, or their modified counterparts. A solvent, typically water, alcohol, or a ,.~,..,1. - -~;~,n thereof, is used to disperse the cx.. . ,1 .. ,r. 1 ~ within the mixture and act as an agent for the gelation ofthe starch-based binder. In addition, the solvent, along with other admixtures such as 3û rheology-modifying agents, plasticizers, and dispersants, help to create a mixture having thedesired rhPn~ l orflow, properties.
The starch-based binder may be added in its ungelated, granular form, or it may be pregelated. As the starch-based bindçr is hçated, the granulçs rupture, thereby allowing the long, single chain, amylose polymers located within the granules to stretch out and 35 interlwine with other starch polymers, such as the highly branched (Llll,~lU~ .Lill polymers.
This process is referred to as gelation. Once the solvent is removed, the resulting W096105254 21~ 7 9~S 9 = " ~ 1 r~ ç l ~?

~ 9 ..~" uu.u~..t~ mesh of starch polymers produces a soiid material However, the relatively ~ high cost of starch-based binder and the excess tlme and energy necessary to remove the solvent make it impractical to make articles solely out of starch.
, To decrease the cost and also to impart desirable properties to the final article, 5 inorganic filiers or aggrega~es are usuallv added to the mixture in an amount greater than about 70% and even up to as high as about 90% by weight of the total solids in the rtiixture. While this range applies to most aggregates of relatively high density (greater than about I g/cm3), in the case of lower density, or ''I;~LLç. _;2,h.", aggregates (having a density less than about I g/cm3), such as expanded perlite or hollow glass spheres, the 10 minimum weight wiU be less and is dependent upon the density of the particular aggregate in question. As a result, it is more appropriate to express the ~ of lightweight aggregates in terms of voiume percent, which will preferably be included in a broad range from about 5~/O to about 85% by volume.
To obtain mixtures having a high cv ~ ;-- of inorganics, the inorganic 15 aggregate particles are selected to have a shape and particle size distribution that preferably produces a high packing density. This process is referred to as particle packing.
It is further preferred that the particles have a relatively small specific surface area Using fiUers with a high packing density amd low specific surfiace area minimizes the amount of starch-based binder and solvent needed in the mixture. By minimizing the starch-based 20 binder and solvent, the material costs and processing time to produce the article are minimized. rul Lh~ ..vl ~, by selecting aggregates having specific mechanical and physical properties, those properties can be imparted into the finai articles. For example, the aggregate can help control the specific heat. density, strength, and texture of the finai article. One preferred inorganic aggregate is calcium carbonate.
Rheology-modifying agents, such as cellulose-based, pc,:~ ' ' based, protein-based, and synthetic organic materiais can be added to control the viscosity and yield stress ofthe mixture. Increasing the viscosity helps to prevent settling or separation within the mixture and aids in the formation of the cellular, structural matrix. In general, mixtures that have a high viscosity produce relatively dense articles having small ceUs in the structural matrix. In contrast, mixtures with a low viscosity produce lighter articles with larger cells within the structural matrix. The formation of the ceUular structural matrix is aiso dependent on variables such as the solvent content and the pressure and L~ C.~Ilul~ applied to the mixture. The rheology-modifying agent will also act as a binder to some extent and can help increase the strength of the article.
Plastici~rs, I~ t~nt~, and porous aggregate may be added to the mixture to increase the flexibility of the articles. Typically, once the solvent is removed to produce w0 96105254 2 the forrn-s~able article~ the resulting article is very brittle. Plasticizers include materials that can be absorbed by the starch-based binder to soften the structural matrix and which have a sufficiently high vapor point so as not to be vaporized and removed during the forming process and that will remain stable after the article is formed. In addition to 5 water, two preferred plasticizers include glycenn and polyethylene glycol. TT~ . '.. . U...l ~, such as MgCI~ and CaCI-, absorb moisture and tightly bind it with the starch-based binder molecules so that the bound moisture is not removed during the forming process. In turn, the moisture improves the flexibility of the finished article. Porous aggregates can hold the solvent during the forming process and then disperse the solvent into the matrix of the 10 forrn-stable article to increase the flexibility of the article. Of course, flexibility may also be imparted to the hardened article through the use of high humidity condition, although this process is not required in all cases.
Calcium sulfate l.~ dl~ dLc (CaSO, ~ 0)l the main hydratable component of plaster of paris, may be used as a water absorption agent within the mixtures of the 15 present invention because it reacts with water to form the calcium sulfate d;hydrate (CaS04 2H~0). This binding of water can be also be utilized as a means for holding water internally.
Medium- or long-chain fatty acids, their salts, and their acid derivatives may be added to improve the release of the hardened article from the mold. Molds having a 20 polished metal surface, or other non-stick surface, are also useful in improving or facilitating the release of the article.
Although not necessary, other . ~ -lp can be added to the mixture to vary the properties of the final product. Such .,~ include fibers, which improve the fracture energy and toughness of the article, cross-linkers, which improve the strength 25 and stability of the article, and ~icp~r~ntc which decrease the viscosity of the mixture without requirin, an increase in the solvent content.
The articles of the present invention are produced through a multi-step process.Initially, the selected . . are blended into a 1- ., "o~. u..~, moldable mrxture.
The mixing can be carried out in a high energy mixer or an auger extruder, depending on 30 the viscosity of the mixture. It is often preferred to apply a partial vacuum to the mixture to remove unwanted air voids that can create defects in the final product.
In the preferred c.,.b~ ' . t, once the moldable mixture has been prepared, it is positioned within a heated mold cavity. The heated mold cavity may comprise manydifferent e...l,od;...~,..Ls, including molds typically used in uu~ Liu~l injection molding i5 processes and die-press molds brought together after placing the hlO~_d~d-~.dl~ filled mixture into the female mold. In one preferred c...bu,l;....,..L, for example, the moldable _, .

WO 96/052s4 ., ,, r~l,o~ ~
~ 2~7~9 Il mixture is placed inside a heared femaie mold. Thereafter. a heated maie mold is;I.r mated with the heated femaie mold, thereby positioning the mixture between the molds. As the mixture is heated, the starch-based binder gelates, increasing the viscosity of the mixture. .~ r ~ Iy~ the mixture increases in volume within the 5 heated mold cavity as a result of the forrnation of gas bubbies from the cva~ula~
solvent, which are initially trapped within the viscous matrix.
Various types of wafer baking machines can be used to mass produce the containers and other articles ~r~ AI~d by the present invention. ru.P c, cu..v.,.--ionàl expanded poi~Ly-c..~, machines can be modi35ed to produce the inventive 10 articles.
As will be discussed later in greater detail, by selectively controlling the Lh...,.lod~ parameters applied to the mixture (e.g., pressure, Lelll~J.,.aLul c, and tune), as weli as the viscosity and solvent content, the mb~ture can be formed rnto a form-stable article havrng a selectiveiy designed cellular structurai matrix. That is, the size, quantity, 15 and positioning ofthe ceDs can be selectively designed to produce articles having desired properties for their intended use. r... Lh~ 0~ c, the surface texture and ~ 5,, ' of ceDs within the structurai matrix can be controlled by selectively varying the ~,.lly~.lalul~:
between the molds and the tc...".. aLul c aiong the length of the molds. Besides controlling the properties among different molded articles, the properties of a single article can be 20 made to vary throughout the article, including varying thickness, varying skin thickness, varying cell structure, and varying density. This may be ~ , for example, by creating within the molding apparatus differential relative L,~ ,.alulc." or differential L~ J.,.atulc wnes, throughout the molding apparatus. As a result, different i.,...!Je.aLulc and processing conditions are imparted to varying locations throughout the same article.
In a preferred ~ 1 o 1: .. 1, the articles are formed with the previously discussed admixtures to impart the desired flexibility to the hardened articles without the need for .a ..~ them in high humidity. In an aiternative .. ~ '' t, the hardened articlesare placed in a humidity chamber where the articles are exposed to a high humidity ~ v;lUll~U~,Ut at a selected t~,ul~J.,.aLulc. The water molecules in the air are absorbed by, 30 and become bound through hydrogen bonding, the starch-based binder portion of the matrix, thereby reducing the brittleness of the binder material and imparting the desired fiexlbiiity to the articles. It is preferred to keep the moisture content in the final article to below about 10% by weight of the starch-based binder component, as excess moisture can allow bacterial growth. More preferably, the moisture content is kept to below about 5%
35 by weight of the starch-based binder ,- , ,, , _ __ ___ _ _ __ _, _ _ _ _ __ _ _ WO 96/05254 I ~
21g~ 05a Once the article is: ' l, a coating can be applied. The coating can have several purposes, which include providing a finished surface to the article, sealing the article, and adding additional strength. The coating cam be applied through various v, ' p}ocesses such as spraying, dipping, sputtering, and painting. In an 5 altemative c I ' t, selected coating materials can be added to the mixture prior to the fommation of the article. If a coating material is used that has a similar melting point as the peak t~..~ ul c of the mixture, it migrates to and coats the surface of the article during the fommation of the article. Such coating materials include selected waxes and cross-linlcing agents.
The resulting articles can be designed to have properties similar to or better than those of articles made from GU.... ~ ' materials, such as paper, paperboard, polysty-rene, metals, plastic, or other natural organic materials. In light of the minimal cost of inorganic fillers and the moderate cost of starch and flours, the inventive articles can also be made at a fraction ofthe cost of w....,~iu~dl articles. Finally, the inventive articles are more ~,.. , '1~ friendly than .,u.. ~.Liu.~l articles. For example, the r ~ ~, process uses no harmful chemicals, emits no hamlful emissions into the air or water, depletes no non-renewable resources, and requires only minimal processing energy.
FU-LI-~ --U-C, the inventive articles are easily recyclable or quickly d ~ , . ' back into the c..~;., 2û
BRIEF DESCRIPTION OF TEIE DRAWINGS
In order that the manner in which the above-recited and other advantages and objects of the invention are obtained, a more particular description of the invention briefly described above will be rendered by reference to a specific c...l,. ' thereof which is 25 illustrated in the appended drawings. ET I ' ' ,, that these drawings depict only a typical ~....I.u l: : ofthe invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the ~ ;..g drawings which are listed h~,., ' ' .. .
Flgure I is a phase diagram showing the L~,UI~ dLU~ ~ and pressure conditions that 30 the mixture is subject to in one ~ S G ~ of the invention during formation of the articles.
Flgure 2 is an enlarged cross-sectional view of the skin and interior section of a bardened article.
Figure 2A is a digitally scanned l ' ~ . ' of the cross-section of an article 3 5 having a tbin outside skin and an interior section containing relatively large cells.

S~S~l~UTE SHEET ~RULE ~6) WO 96105254 r~
~ 219 sO~
13 ;;~
Figure 2B is a digitaily scanned ~ 1 ,~ p~ of the cross-section of an article - having a thin outside skin and an interior section contairing relatively medium celis.
Figure 2C is a digitaily scanned j ' ", ' of the cross-section of an articie --~ having a thick outside skin and an interior section containing relatively large ceiis.
Figure 3 is a cross-sectionai view of a maie mold and a femaie mold being mated.Figure 4 is a perspective view of load ceiis and mixing apparatus.
Figure 5 is a cross-sectional view of an auger extruder apparatus.
Fgure 6 is a cross-sectional view of a two-stage injector.
Fgure 7 is a cross-sectionai view~of a ~ u.,c.Li..g screw injector.
Fgure 8 is a perspective view of a maie mold and a female mold.
Fgure 9 is a cross-sectionai view of the femaie mold being fiiied with a moldable mixture by a fiiiing spout.
Figure 10 is a cross-sectionai view ofthe above maie mold and femaie mold being mated.
Figure 11 is a cross-sectional view of the inventive article baked between matedmolds.
Figure 1 lA is an eniarged cross-sectionai view of the vent holes between the mated maie mold and femaie mold.
Figure 12 is a .,.u ... s~,~,Liu~l li view of the femaie mold having a scraper blade 20 removing excess materiai.
Figure 13 is a cross-sectionai view of a duai mold.
Fgure 14 is a cross-sectionai view of a spiit mold with suction nozzie.
Figure 15 is a perspective view of a baking machine.
Figure 16 is a perspective view of a mold in the fiiiing position in the baking 25 machine of Figure 15.
Figure 17 is a perspective view of a scraper blade operating with the baicing machine of Figure 1~
Fgure 18 is a cross-sectional view of a female mold and maie mold used in a Cull~ lLiullai expanded pol~Lyl~,..., machine.
Fgure 19 is a cross-sectionai view of the molds used in a cu.. ~ Liu~dl expandedpol~i,iy~ . machine in a mated position DF.T~n.FD DESCRTPTION OF TEIE PREFERRED EMBODllVl~TS
L INTRODUCTlON.
The present invention relates to novel .. I,c~ and methods for ' ~ articles of r e from particle packed, ;,w.~ fiiied materiais SU~ UTE SHET ~ULE 261 . . ~ . .

wo 96/05254 F~l/~J.,.
.: ' '' ' 219'('05~ 14 having a starch-based binder and a l~ u~odv "v controlled celiular maerix. The inventive materiais can include a variety of ~"v;.,~y safe ~u~ "I"J "1 C, including a starch-based binder, water. inorgan-c and organic aggregates~ mold-releasing agents, fibers, rheology-modifying agents, cross-linkers, plasticizers, dispersants, and coating 5 materials.
A matenals science and -llfc,l u~-l u-lul ~ g approach is used to 5elect the type, size1 shape, and proportion of each component that, when blended together, result in a mixture and subsequent final product having desired properties at an optimai cost.
The desired properties are dependent on the required handling and the intended use of the 10 fnished article. The optimal cost is obtained by selecting s~ that wi.'l max n~ize production output while minimizing material and production costs.
Using a ~ u~- U~.lUf di ~ approac4 the present invention can produce a variety of articles, including plates, cups, cartons, and other types of containers and articles having mechanical properties s~-' ' "~ similar or even superior to their 15 wuu ., ~ made from w~ io~ci materiais, such as paper, pGl~ yltlle foam, plastic, metal and giass. The inventive articles can aiso be made at a fraction of the cost of their cOI.~ iollrl cuuut, l~ . The minimal cost is a resuit of the relatively il.~.lA~aggregate which typically comprises a large percentage of the mixture and the minimum processing energy required.
The r ~ processes and resulting articles are aiso less harmful to the C..~;.u~ than ~ t-o,.~i processes. For example, Ih~v.~ "~ all of the ", . .., r, 1, ,, ;. .., waste can be recycled into the production line. Once the finished articles have fulfilled their intended use, the articles, which consist of naturally occurring organic and inorganic materials, are easily J' u \ l ~-J back into the eart4 or recycled. As a 25 result, the inventive articles do not create the .,.I...UIIIII~,.ltal biight or consume the landfills as do similar articles made from .,u..~..liu.,~l materials.
The articles of the present invention are produced by initiaily blending selected .~,",p" 1~ into a 1~... o~,. u~c, moldable mixture. The moldable mixture includes a str.rch-based binder, such as potato, com, waxy com, rice, or wheat starch, an inorganic 30 aggregate, such as ca cium carbonate, and a solvent, such as water or alcohol. The shape, size distribution, and specific surface area of the inorganic aggregate are selected to maximize the packing density of the mixture and minimize the starch-based binder and solvent requirements. The addition of high ~ ;" - of inorganic ag,gregate filler perrnits the articles to be made more quickiy, less ~,A~ , more c..~ ;., "J/ safe, 35 and with a lower specific heat in CUIIIIJ~ UII to articles made without or with only low CUII~ UII~II;UIIS of inorganic aggregate. Accordingly, the materials and articles of the _ . . .

W0 96/0s254 ~ 9 J ~ . S

~ , , .,, . " ~

presen~ invention are often referred to as being '';,w,O "y filled" or "highly c inorsganically filled. "
Admh~tures can be combined with the mixture to impart desired properties to the articles. For example, rheology-modifying agents and dispersants can be added toregulate the viscosity of the mixture. High viscosity mixtures are used for making dense articles having small cells within the structural matrix. Low viscosity mixtures are used for making low density articles having large cells within the structural matrix. Plasticizers, humectants, and porous aggregates can be used for imparting the desired flexibility to the articles during the forming process. Other additives include fibers, which increase the fiacture toughness of the article, dispersants, which decrease the viscosity of the mixture without the addition of solvent, and selected coating materials, which can form a coating on the articles during the formation process. Aggregate particles upon which ettringite has been formed may be used to improve the interaction between the aggregate particles and starch-based binder.
Once the moldable mixture is prepared, it is positioned vithin a heated mold cavity. The heated mold cavity may comprise many different _ l o~ , including molds typically used in ~,u_.lliu--di injection molding processes and die-press molds brought together after placing the ,, ~ filled mixture into the female mold. ln one preferred . . .l v ~ f, for example, the moldable mixture is placed inside a heated female 20 mold. A heated male mold is then ~ , " ;1~ mated with the heated female mold,thereby positioning the mixture between the molds. By carefully controlling the L~ LUI~ and pressure applied to the mixture, as well as the viscosity and solvent content, the mixture can rapidly be formed into f~r~ 5~hle articles having a selectively designed cellular structural matrix. That is, the surface texture and the fommation of the 25 cells within the structural matrix are selectively controlled by varying the r ' and thetr relative ~ u ,.l ;.,. . - within the mixture. as well as the ll..,. l"o~ly",_,.._ processing conditions. The result is the ability to r ~ a wide variety of containers and other articles that have greatly varying thermal and mechanical properties ~,u, I ~ v~di-.~ to the p~.~u.",~.. e criteria ûfthe article.
In one r, . .l .v~ , the articles are forrned having the desired flexibility for their intended use. In an altemative l o l~ ~ h the self-supporting articles are placed in a humidity chamber where they are exposed to controlled relative humidity at a selected .,."~ lu, ~. The water is absorbed by the starch-based binder through hydrogen bonding of the water molecules to the hydroxyl groups of the starch. thereby softening the starch-based binder and imparting the desired flexibility to the articles. A coating material can be appiied either in the mixture before the article is formed or the coating can be applied wo 96/05254 21~70~ 16 externally after the article is formed. Subsel}uem processing of the articles can include printing, stacking, and boxing.

M. i~FFi(N~TlONS.
S The terms ''il~v.v 'Iy filled mixture." "mixture." or "moldable mixture" as used in the ~ - and the appended claims have ul~ hdnv~dvlf meanings and shall refer to a mixture that can be formed into the articles which are disclosed and claimed herein.
Such mixtures are ~ by having a high ~n... _..u A~ of inorganic filler oraggregate (from about 20% to about 90~/O by weight of the total solids in the mixture for 10 most aggregates, and from about 5% to about 85% by volume of the material in the case of lightweight aggregates), a solvent, and a starch-based binder. The moldable mixtures may also include other admixtures, such as a mold-releasing agent, fibers, organic aggregates, dispersants, cross-iinkers. rheology-modifying agents, plasticizers, and coating materials.
As used in the ~ and the appended claims, the term "total solids"
includes all solids, whether they are suspended or dissolved in the mixture. The volume of the totai solids does not include the interstitiaA voids between the solids, but is calculated by subtracting out the volume of the interstitial voids.
The terms ''i..vlV ~ "~ filled, cellular matrix", "ceilular matrix", or "structurai 20 matrix" as used in the ~ r _1;"" and the appended claims are h~t~ f and shail refer to matrices of the article after hardening of the moldable mixture.
Both the moldable mixture and the cellular matrix formed therefrom each constitute " ,, "~ fiiledl ceiiular materials" or ~ v~ filled materials". These terms as used in the ~ r ~ and the appended claims are ~' v ' '~ and shali 25 refer to materials or .,. ~ without regard to the amount of solvent or moisture within the mixture and without regard to the extent of gelation of the starch-based binder.
The term "hardening" as used in this ~L~ and the appended claims refers to the prvcess of gelation of the starch-based binder and removai of the solvent to produce a form-stable article. The term "hardening," however, is not limited by the extent of 30 gelation or the amount of solvent removed.
The term "form-stable" as used in the ~ '' -8~ and the appended claims means that the article has a structural matrix which can be removed from the mold, support its own weight, and can continue through subsequent processing without damaging rl~fnrrn~ n ofthestructuraimatrix. r.-.~ ol~,theterm"form-stable"meansthatthe 35 article has sufticient solvent removed from its matrix so that the articie will not bubble or crack as a result of vapor expansion once the article is removed from the molds. It will WO 96/os2s4 ~ 1 9 ~ 9 be understood, however, that moided articles are sfill considered form-stable even though they may contain a small percentage of moisture.

IIL CO~CEPTUAL OVERVIEW OF FORMATION PROCESS.
S A. M;~ . al F _ ; _ Desi~n.
The.illwL ' "5 filled materials of the present invention are developed from the perspective of Ull-~l uaLI u-,Lul di engineenng in order to build into the .,.._~ uaL~ U~,IUI r of the material certain desired, ylrd~:rll l properties, while at the same time remaining cognizant of costs and other r 1' ' ' r.,. ~ ...0, c. this microstruc-I û tural engineering analysis approach, in contrast to the traditionai trial-and-error, mix-and-test approach, has resulted in the abiiity to design illU125~11h~lly filled materiais with those properties of strength, weight, flexibility, insulation. cost, and cllvllulull.,.lL i neutrality that are necessary for the production of functionai and useful containers amd other articles.
The number of different raw materials available to engineer a specific product is 15 enormous, with estimates ranging from between fifty thousand and eighty thousand. They can be drawn from such disparately broad classes as metais, polymers, elastomers, ceramics, glasses, c~mp~it~s~ and cements. Within a given class, there is some ' .y in properties, processing, and use-patterns. Ceramics, for instance, have ahigh modulus of elasticity, while polymers have a low modulus; metals can be shaped by 20 casting and forging, while composites require lay-up or special molding techniques;
1.~.' ' "~ settable materials, including those made from hydraulic cements, historicaliy have low flexural strength, while elastomers have high flexurai strength and elongation before rupture.
~'~ , ' of material properties, however, has its dangers; it can lead 25 to r ~ (the metallurgist who knows nothing of ceramics) and to ~,_. VdLiVt thinking ("we use steel because that is what we have always used"). It is this n and cunsc~ L;ve thinking that has limited the ~U ~ of using hlul~,dllh,dlly filled materials for a variety of products, such as in the l"~.uurd~,Lu,c of containers and other packaging materials.
1~ c, Ll.~L,ss, once it is reaiized that ~ filled materials have such a wide utiiity and can be designed and ull~.luaLIuuLuldlly engineered to have desired properties, then their , . ' ' ' ~.y to a variety of possible products becomes appreciable. Such materiais have an additionai advantage over other ~.u,l~. ' materials, in that they gain their properties under relatively gentle, n, ~1 ~Ag;~g, hl.,AIJ~,.Iaive conditions. (Other materiais require high energy, severe heat, or harsh chemical processing that si~lLly affects the material ~ 5~ and cost of ~ r ~ g ) Moreover, certain , . . ..... .. . . .. : .. . . . , _ .. .. . _ W0 96105254 ~ IA
2~9~)S9 1~

CU~ ,UtiUllai materials, or l u~ ul l~ thereof, can be hlCUl~lJUld~t:d into the materials of the present invention with surprising synergistic propenies or results.
Phe design ofthe ~ --lul~ ;l;u~lC ofthe present invention has been developed andnarrowed, first by primary constraints dictated by the design, and then by seeking the S subset of materiais which maximizes the p...rUllllahl~,C of the c ~ At ail times during the process. however. it is irnponant to realize the necessity of designing products which can be Illallhrac~uled in a cost-competitive process.
Primary constraints in materials selection are determined by the properties necessary for the anicle to function successfuliv in its intended use. With respect to a 10 food and beverage container, for example. those primary constraints include minimai weight~ strength (both C,ulll~ Ic~a;~c and tensile), flexibility, and toughness It~u;.~ b, while ,~ keeping the cost UUIllua~dblc to its paper, plastic, pol~ , or metal eUU~CllUr~
In its simplest form, the process of using materials science to Illi~.lU;~
15 engineer and design an inorganically anicle requires an I J' ~' ~ of the , '~ ' . between each ofthe mixture I , , the processes pararneters (e.g.
time, Lclll~ .dlulc, pressure, humidity), the mixture propenies, and the properties ofthe finai articles. By ~ A~ )' the I ' ', bet veen the variables at both the macro and micro levei, oDe skhied in the art can select ,u. U!JUI liu..~. of desired ~ r 20 that can be processed under selected conditions to produce anicles that have desired propenies for an intended use at a minimum cost.
The i ~ laLiu~L~lhu ~ between the variables will be discussed at selected locations in the appiication where the variables are introduced and def ned. Specific "---T ~- -are set fonh in the examples given later in order to A - ~ how the seiection of 25 variables can optimize properties.

B. Articles of ~, ' c.
Using a Illi~.lu~Llu~,Luldl ~ ;i"~,.,.i"g approach, a variety of articles can beproduced from the processes and ~u~ lul~c of the present invention. The terms 30 "article" and "article of ulahlura~lulell as used in the ~ and the appended claims are intended to include ail goods that can be formed using the disclosed process.
Examples of such anicles of manufacture include containers, such as food and beverage containers and packaging containers. Articles within the scope of this invention also include such disparate objects as cutlery, flower pots. mailing tubes, light fixtures, ash 35 trays, and game boards.

W0 96/05254 ~ 9 J ~

The terms "container" or "containers," as used in the ~ n and the appended claims, are intended to include any receplacle or vessel utiiized for, e.g., packaging, storing, shipping, serving, portioning, or dispensing various types of products or objects (inciuding both solids and liquids), whether such use is intended to be for a 5 short-term or a long-term duration of time.
Containers within the scope of this invention include, but are not limited to, the following: cartons, boxes. sandwich containers, hinged or two-part "clam sheii"
containers, dry cereai boxes, frozen food boxes, milk cartons, fruit juice containers, carri-ers for beverage containers~ ice cream cartons, cups (including, but not limited to, dispos-10 able drinicing cups, two-piece cups, one-piece pleated cups, and cone cups), french fry containers used by fast-food outlets, fast-food carry out boxes, packaging, support trays (for supporting products such as cookies and candy bars), cans, yoghurt containers, sieeves, cigar boxes, ~ ~ y boxes, boxes for cosmetics, plates, vending piates, pie plates, trays, baking trays, bowls, breakfast plates, ..u~ ~le dinner trays, "TV"
15 dinnertrays, egg cartons, meat packaging platters, disposable singie use iiners which can be utiiized with containers wch as cups or food containers, ' ~ ".~, sphericai objects, bottles, jars, cases, crates, dishes, medicine vials, and an endless variety of other objects.
The container should be capable of holding its contents, whether stationary or in movement or handiing, whiie ~ _ its structurai integrity and that of the materiais 20 contained therein or thereon. This does not mean that the container is required to withstand strong or even minimal externai forces. In fact, it may be desirable in some cases for a particular container to be extremely fragile or perishable. The container shouid, however, be capable of perfom~ing the function for which it was intended. The necessary properties may always be designed into the materiai and structure of the 25 container beforehand.
The container should also be capable of containing its goods and its integrity for a sufficient period of time to satisfy ils intended use. It will be appreciated that, under certain c;.~ , the container may seai the contents from the externai c..~;..,.ù...,..~, and in other ~,h~,u~ L~aces may merely hold or retain the contents.
C. products used in c., J l l;.. ll with the containers are also intended to be included within the term "l ." Such products include, for example, iids, straws, interior packaging, such as partitions, liners, anchor pads, comer braces, comer > protectors, clearance pads, hinged sheets, trays, funnels, cushioning materials, and other object used in packaging, storing, shipping, portioning, serving, or dispensing an object within a container.

_ . _ ... . . ... ..... . . .. : . . ... . . ... : . . _ _ _ .

W096/05254 . r~"~
~lg~5~ "o The containers within the purview of the present invention may or may not be classified as being disposable. In some cases~ where a stronger, more durable co....~. uutio~
is required, the container might be capable of repea~ed use. On the other hand, the container might be ",~,uL.,.u- cd in such a way so as to be economical for it to be used 5 only once and then discarded. The present containers have a ~ v~ ;~ .n such that they can be readily discarded or thrown away in cu..~.."iv.,~.l waste landfiii areas as an c"~ neutral material.
The articles within the scope of the present invention can have greatly varying thicknesses depending on the particular application for which the article is intended. They 10 can be as thin as about I mm for uses such as in a cup. In contrast, they can be as thick as needed where strength, durability, and or bulk are important C~ For example, the article may be up to about 10 cm thick or more to act as a speciaiized packing container or cooler. The preferred thickness for most articles is in a range from about 1.5 mm to about I cm, with about 2 mm to about 6 mm being most preferred.
Thephrases"mass-producible"om-~,ura-lu,eiina"cu",,.. ,. c;ai~ or"economic"
manner are intended in the ~ 1l and the appended claims to refer to the capability of rapidly producing articles at a rate that makes their u~ uL~.~h~t ~ "~
comparable to articles made from ~ u..~,.liiu..dl materials, such as paper, paperboard, pol~ ,c"~i, plastic, ormetal.
The containers and other articles made from i"o.L, ".~, fiiled materials are intended to be competitive in the ' ~ with such articles currently made of various materials, such as paper, plastic, polystyrene. or metals. Hence. the articles of the present invention must be economicai to r c (i.e., the cost wili usuaiiy 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 articles of the present invention to be ~ "~, mass-produced is a significant limitation on the quaiities of the materiais and products.

C Processin~ ConceDts and Variables The present section discusses the underlying concepts and processing variables used in r ' ' ~ the articles of the present invention. A detailed description of the mechanicai apparatus and systems used in the ~ ~ process will be provided later in the disclosure.
The mixture of the present invention is prepared by combining selected 35 ~ and blending them until a illh~, -- v~c~ moldable mixture is formed. The dry cnmpnn~nr~ are typicaliy mixed first. The liquid ~ .u- : ., such as water, are then wo g6~0s~4 2 1 ~ 7 0 ~$ ~ J ~ IJI ~ ~;.

blended into the mixture. In one r~ the mixture is prepared in a sealed chamber to which a negafive pressure or vacuum is applied. The applied vacuum both removes and prevents the G ~ ' of air bubbles within the mixture. The advantage of this is because entrained air bubbles tend to mi_rate to the extenor surface of the article during 5 the forming process, which may result in a product having increased surface defecls and lower structural integrity.
Once the mixture has been prepared, it is forrned or molded into the shape of the desired article. In one ~ ~1 v 1; ,1, the forming steps include positioning and locking the mixture between a heated male mold having a desired shape and a heated female mold 10 having a ,~ A y shape. The heat from the molds causes Ihe mixture lo expand within the molds. Excess material and vapor is expelled from between the molds through small vent holes. Once a sufficient amount of the solvent has been removed, the molds are opened, and the form-stable ar~icle having a cellular structural matrix is removed for subsequent processing.
The process is more accurately defined through the use of a phase diagram.
Depicted in Figure I is a phase diagram for water. Figure I illustrates, by way of a general example, the pressure and ~ .,.alule stages that a mixture using water as a solvent undergoes during formation of the article. Between points A and B along line 1, the mixture is locked between the molds and is rapidly heated at first at constant ambient pressure to a Icul~,.a~ul G of about 100~C. The portion of the mixture closest to the molds is healed at a faster rate and thus reaches a t~ alule of 100~C before theinterior section of the mixture. As the mixture begins to heat, the starch-based binder begins to gelate, increasing the viscosity of the mixture. (The process of gelation is discussed later in the section on starch-based binders.) Once the i , of the water within the moldable mixture in contact with the mold surface reaches 100~C, the water begins to vaporize, thereby forming air pockets or voids within the mixture. As a result of these expanding pockets, the volume of the mixture expands, causing the mixture to "rise," thereby filling the mold and ~ u.~ uily clogging the small vent holes. The water or solvent within the portion of the moldable mixture closest to the molds is quickly vaporized and driven offfrom the mixture at or - near the region closest to the mold, as ,t~!.t~,.,t~,d in Figure I by point B, thereby hardening that portion of the mixture into a thin, dense skin. The skin is believed to be , formed almost :.. .1_.,1~.. ~.. ~ly amd acts as an insulation barrier for the remaining portion ofthe moldable mixture, thereby slowing down the rate of heating. With the vent holes 35 plugged, and due to the restricted flow, the pressure begins to increase between the molds, as shown by line 2, preventing the i ~ r ~ of the remaining solvent into ... ... ........ ... . . .. . . . . _ . . _ .. ... . .

wo s6/0s2s4 2 ~ o s 9 . ~

''2 vapor at the boiling point. which is usually 100 = C for water. Instead, as aiso shown by iine 2, the soivent in the moldable mixture is super heated as a result of the restricted fiow.
E:ventually, the material blocicing the vent holes ruptures. aiiowmg excess materiai to escape from between the molds. However, as a result of the small size of the vent holes, 5 the flow of the escaping mixture is restricted, thereby ailowmg the pressure and Le~l~y.,.aLul c within the mold to further increase to point C on Figure 1.
The cellular structural matrix is formed when sufficient excess materiai has cscaped to cause the pressure to cirop between the molds. Under high pressure the solvent vapor which forms is nucleated because of ~n~ c The drop in pressure 10 causes the ~u~..,.h.,~.ed solvent to transform rapidly into the gaseous state through an adiabatic expansion, thereby forming a distribution of voids or cells throughout the stiuctural matrix of the article. The tendency of the solvent vapor to become nucleated at individuai points throughout the c ~p~rhr~tr~l mixture yields a fairly well-distributed ceii structure. The ~ . of the solvent to vapor is an e 1~ ' ' reaction that 15 absorbs heat from the moldable mixture, thereby ' "~ decreasing the t~ y~aLulc of the moldable mixture inside the mold. The drop in t~ aLul c and pressure of the moldable mixture is depicted by line 3 extending from point C to B. The iliustration that the kll~ ,.aLu~c of the mixture returns to 100~C is simply by way of example. iln actuaiity, the ~.,...~,c. aL~Il c of the mixture may drop below 1 00~C. The drop in pressure 20 of the solvent is depicted as line 5 extending from point C to D.
With the vent holes open and the pressure reduced, the mixture then begins to heat up again to the boiiing point of the solvent, ailowing the remaining solvent to freely evaporate untii sufficient solvent has been removed for the article to become form-stable.
This process is depicted by line 5 extending from point B. This anaiysis of the ceiiular 25 formation is supported by the fact that producing articles under low pressure results in articles having minimai voids. For example, gradually C~ ulaLi~g the solvent from the mixture at a low t.,...p~,. aLul ,~ or heating the mucture rapidly on top of a single mold results in a product having a lower C~ l aLiull of air voids and high density.
Depicted in Figure 2 is a II..~,IUS-~U~J;C image of a cross-section 8 of a formed 30 aiticle. The figure reveais the present a~ticles as having an outside slcin 10 with small cells 12 and an interior section 14 containing large cells 16. Small celis 12 are defned as having an average diameter of less than about 250 ,um. The materiai between adjacent cells is referred to as a ceil wali 18. The distribution and size of the cells within the sttucturai matrrx are dependent on several v aiiables including the viscosity of the mixture, 35 tc~u~ aLulc ofthe molds, and c~ ofthe mrcture, i.e., types and amounts of solvent, starch-based binder, aggregate, rheolo~,y-modif,ving agent, and other admixtures.

.

w0 96/052s4 , ~ L S '~

23 ''' ' t r. I ~
Articles can be made having a desired structural malrix by controlling the related variables. For example, Figure 2A is a Illh~ u~,u~ , picture of the cross-section of an article having a thin outside skin 10 and large cells 16 located in interior section 14.
Figure 2B is a .",~- Ua~,UIJ;C picture of the cross-section of an article having a thin outside skjn 10 and medium cells 19 located in interior section 14. Finally, Figure 2C is a Illk.l u~,up;C picture of the cross-section of an article having a thick outside skin I û and large cells 16 located in interior secrion 14. In general, the insulation ability and the strength of the structural matrix of the article increase as the cells become more evenly dispersed throughout the matrix. Increasing the overall volume of the cellular space also would tend to improve the insulation ability, although it would be expected to have an adverse effect on the strength of the matnx. The insulation ability can be improved without s;~;,,;L.,cu.dy sacrificing strength by addiny an efflciently particle packed, Gghtweight aggregate to the matrix.
The size of the cells within the structural matrix is heavily infiuenced by the viscosity and/or state of hardening of the article. As previously discussed, outside skin 10 is forrned early on in the process and is important for the structural integrity of the article. Accordingly, when the pressure drops and the cells are formed within the mixture, it is much easier for the vapor to expand within interior section 14 than in outside skin 10.
Thus, the cells are much larger within interior section 14. It is also possible that the cells in outside skin 10 are fommed at the same time the skin is fommed. That is, as the solvent vaporizes within the portion of the mixture forming outside skin 10, small bubbles begin to fomm within the skin. Howeva, the outside portion of the mixture is heated so quickly that the skin becomes hard before the cells have a chance to enlarge.
As stated above, it is important to remove enough solvent so that the article can be removed from the mold and be adequately form sLable. Ln ganaal, the structural matrix ofthe molded articla will contain about 5% or less solvent at the point where the article has adequate strangth and stability to be demolded. The need to remove this relatively high quantity of solvent in order to create a fomm stable article that can be demolded properly results from the tendency of the vaporized solvent within the cellular matrix to further expand after the demolding step. Thus, an ;,~ dried article has a - tendency to "blow up" upon damolding due to the high intemal pressure of the vaporized solvent.
-~ Howeva, this high intemal pressure can be greatly reduced by the application of a cooling cycle ;".",~,d;~Lel~ following the heating cycle before the article is demolded.
35 Cooling the structural matrix of the article causes the solvent to recondense, thereby reducing the intemal pressure caused by the vaporizing solvent during the heating cycle.

_ _ _ _ . _ . _ .. ~ ;. : ., . ... .. . ... . .. ,,, . _ .. _ . _ . . . . _ _ wo s6/0s2s4 ' : ' r~.,.J~.
219~5g The application of a cooling cycle allows for the demolding of the article whilemaintaining adequate intemai moisture to main~ain fexibiiity and resilience, WhiC4 in turn, obviates the need for a subsequent r,....~;.;r..,;.,g step.
The viscosity of the mixture during the formation process is a function of the 5 . . . ~ of the mixture and the processing parameters. As will be discussed later rn the section on ~ the viscosity of the mixture can be selectively adjusted by the types of starch-based binder and the amount of solvent added. Rh~lo~s~ ...J i;i;' ,, agents and dispersants are also used to control the viscosity. By using mixtures having a low viscosity, the vapor formed by the solvent can more easily expand, thereby10 producing low-density articles having large cells. Mixtures having a high viSCoSjty make it more difticuit for the vapor to expand, thereby producing denser articies having smaiier cells.
In one .,..i.o 1' , in order to control the ceii size the mixture is pre-cooked before being formed into the desired shape. The moldable mrb~ture is pre-cooked by 15 heating the mixture, such as by a pressure cooker or microwave, to the point of gelation of the starch-based binder. The exact L~ lu. e depends on the type of starch-based binder being used. ror example, potato starch gelates at about 65 ~C. By geiating the starch-based binder before positioning it between the molds, the amylose poiymers within the starch granules are better able to extend and fuliy rntertwine before hardening.
20 ru. Li.~ .--u,~;, the viscosity of the mixture is higher when first placed between the molds.
As a result, the fLnished article has increased strength and smailer7 more unifomm cells. As wiii be discussed later, different types of starch-based binder have different effects on the formation of the cells.
The processing variables associated with the fomlation ofthe inventive articles and 25 the ceiiular structural matrix rnclude mold h,...~ Lul~, time for removing the solvent, fiiiing volume, vent hole size, and the cycles of opening and closing of the molds prior to locking of the molds. The articles of the present invention are preferably removed from the locked molds after most, but not ail, of the solvent (typically greater than about 95~/0) has been removed. While the mixture is locked between the molds, the outside edges of 30 the articles are supported by the opposing molds. Vapor fommed by the cv~.!,u.~liun of the solvent is thus forced to travel under pressure to the vent holes, where it is expelled.
The outside walls of the article are the first to fomm and are brittle as a result of the loss of water. Separation of the molds prior to removing ' "~ aii of the solvent permits the vapor to expand between the article wails, resulting in bubbling, cracking, or 35 d..ul ...~.liu.. of the outside walls of the articles. ru, Ih~.lllùl~, attempts to remove the WO 96/05~54 2 ~ 9 7 ~ ~lg .

,.
article from the molds pnor to removal of a sufficient amount of moisture can result in the - article sticking to the molds and damage to the structural matrix.
Since the articie cannot be removed until after the solvent has been s ' ".y removed, it is preferable to have the mold ~ ;Ul~ as high as possible. This minimizes 5 the time for removal of the solvent and permits the quickest production of articles.
Studies, however, have found that ~ y~ lLuluS above about 240~C result in IJ. .U;~ I;"A or breaking down of the starch molecules in the surface of the article.
D u ;~ I ;"A carmelizes the starch, pro,duces a brown color on the article, and reduces the structural integrity of the article. Temperature above about 240~C can also burn 10 certain organic fibers if used. In addition, overdrying the molded articles leads to shrinkage and cracking. Some amount of moisture should, therefore, rematn within the structural matrix of the article.
In contrast, it is difiicult to form an article hlving a cellular structural matrix at mold t~~ tUI t~ below about 120~C. At such low L~ Lu~ ~,.., there is little pressure 15 build-up and only slow evaporation ofthe solvent. Studies have found that increasing the processing t~ aLul~ to between about 140-240~C decreases the production time andthe density ofthe article. With t.,~ Lu~u~ ranging between 140-180~C, the decrease in production time is substantial. After about 180~C, however, the decrease in processing time is rather iimited. Again, this finding is consistent with the cellular formation model.
20 The higher ~ . ~,,, result only in a marginal decrease in the formation time because they only marginally shorten the incubation period before the drop in pressure and they only marginally shorten the time for removing the moisture after the cellular structure is - formed. The k.. ~,. . Lu~ ~ of the molds has little, if any, significant effect on the rate of formation of the cells after the drop in pressure.
AstheLe... ~.~utu-~increases,thesizeofthecellsalsoincreases. Thesizeofthe cells within the structural matrix, and thus the strength and insulating capability of the articles, can thus be selected in part by adjusting the t~ e~aLu~e of the molds.
Fu Ltl~ UIUI ~ by varying the t~ aLul ~ differential between the male and female molds~
the cell size can be selectively varied between the walls of the article. For example, by 30 making the female mold hotter than the ,,u- ~ ~-r ~- g male mold, a cup can be formed having relatively large cells and higher insulating capability at its outside surface where the cup is held. In contrast, the cup will be more dense and be more water tight at its inside -~ surface where liquid will be held.
A Ltlll~ Lul~ of 200~C is preferred for the rapid production of thin-wa~ed 35 articles, such as cups. Thicker articles require a longer time to remove the solvent and are preferably heated at lower , .,~ to reduce the propensity of burning the starch-WO 96/05~ P~

based binder and fiber. Leaving the articles within the locked molds too long can alsoresult in cracking oml~f~ itm ofthe articles. It is theorized that removing greater than about 98~,/o of the solvent within the mixture results in shrinking of the structurai matrrb~, which rn tum can crack the article. Accordingly, the article is optimaily removed from the 5 mold when ~""" u~ tly 2%-5~./o of the moisture remains within the article. It should be understood, however, that these figures are only rough a~ u~~ iu..~,.
The ~ J. IaLu~c of the mold can also effect the surface texture of the molds.
Once the outside skin is fommed, the solvent remaining within the interior section of the mrb ture escapes by passing through minute openings in the outside skin and then traveiiing 10 between the skin and the mold surface w the vent holes. If one mold is hotter than the other, the laws ofthermodynamics would predict, and it has been empirically four.L that the steam will tend to trzvel to the cooler mold. As a result, the surface of the article against the hotter mold will have a smoother and more uniform surface than the surface against the cooler mold.
The Lt~ .dLulc ofthe molds can also be varied along the length ofthe molds.
Depicted in Figure 3 is a male mold 15 mated with a female mold 17, with a moldable mrb~ture being positioned lh~leb~ In general, the male mold includes a top end 6 and a bottom end 7. Likewise, the femaie mold includes a top end 9 and a bottom end 11.
Located near top ends 6 and 9 are vent holes 13, through which the excess material and 20 vapor can escape. Studies have found that for deep recessed articles such as cups, a smoother surface and more uniform structural matrix can be obtained if the mixture is hardened i "y firom the point rul Ih~ 05l from the vent hole to the point closest to the vent holes. For example, referring to Figure 3, it is preferable in some cases for the t~ r ' C of the molds to be the highest at bottom ends 7 and 11, with the t~ .dLu~ c 25 gradually decreasing toward top ends 6 and 9, where the h..ll~ .dlul c is the lowest.
Such a U~ .l aLul e zone di~ferentiai within the molds helps to direct the vapor and air out the vent holes. As the solvent is vaporized at the bottom end of the molds, the vapor is absorbed into the adjacent mixture. The vapor thus graduaily travels to the vent holes. Fu- ll,.,l .,.u. c, since the mixture closest to the vent holes is the last to harden, the 30 excess materiai is more easiiy expelled from between the molds. In contrast, if the molds were hottest near top ends 6 and 9, the vapor near bottom ends 7 and 11 would beforced to travel over the already hardened surface of the article, thereby possibly damaging the surface texture. Likewise, the excess material would aiready be hardened and its removal could result in disrupting the structural integrity of the article.
The mold t~ . .dLul c and the time for removing the solvent are i.. t~,. d~ ,.. d~, and are further dependent on the thickness of the article and the amount of solvent ~ WO 96/L15254 2 1 g 7 0 S 9 , '7 present. The mold ~u..~ ,.aLul~ of the presem invention is preferably in a range from - about 150~C to about 220~C~ with about 170~C tQ about 210~C being more preferred, and from about I 90CC to about 200~C being most preferred. However. thicker articies may require lower ~ J.,.aLulca. The time in which the solvent is preferably removed 5 from the mixture ranges from about I second to about 15 minutes, with about 15 seconds to about 5 minutes being more preferable, and from about 30 seconds to about I minute being most preferable. It should be noted that in light of the ~ h ~ process of the J,;~ of the solvent and the rather short period of time that the molds are in contact with the mixture, the mixture within the interior of the molded article generaiiy 10 does not get as hot as the molds. Typicaily, the lcl~ ,.a~ulc of the mixture wiii not exceed about 130~C.
The volume of materiai positioned between the molds for subsequent heating aiso effects the resulting density of an article. If not enough materiai is introduced into the mold to form a complete article (no excess materiai is discharged) the resulting materiai 15 wiii have a higher density and moisture CQntent. This results from a lack of pressure buiid up and subsequent expansion. When sufficient materiai is added to produce the desired pressure (a minimum of excess materiai) the density of the article t'~ decreases.
Further increases in the amount of materiai wiil decrease the density of the article up to a point. Past this point, the addition of more material wili have iittle or no further 20 effect on the resulting density. For example, in the production of 12 oz. cups, the addition of I gram of extra materiai resulted in a decrease in density of about 0.005 glcm3.
However, adding more than 35 grams of materiai resulted in no further decrease in the density and was merely wasted.
The pressure buiidup within the molds is dependent both on the L.,..."~.. aLul~ of the 25 molds and the size of the vent holes. The larger the vent holes, the less pressure that buiids within the moldable mixture, resulting in less expansion and a more dense structurai rnatrix of the molded article. Accordingly, the larger the vent holes, the smaiier the celis within the structurai matrLx However, if the vent holes are too large, the mixture wiii not be able to plug the vent holes, thereby preventing the required pressure buiidup for the 30 formation ofthe desired ceii structure. (Such an a~ ,,L may be preferred, however, if a more dense afficle is desired.) Another drawback to large vent holes is that they can create larger deformities on the surface of the articles at the point where the excess ~ materiai is removed. The size ofthe deformities can be reduced by decreasing the size and increasing the number of the vent holes.
If the vent holes are too smail. an excessive pressure wiil build up, resulting in ~nnn~tinn or even explosion of the article upon release of the pressure. The size of the . ~

wo 9610s2s4 ;;
059 ~8 cells can further be regulated by controlling the release of pressure. ~or example, by slowing down the rate of pressure drop, the sudden expansion force caused by u- ;~L;o.. of the solvent is decreased. This results in articles having smaller ceiis and thicker cell walls, which together produce a stronger article.
S As previously discussed. by re uiating the size of the vent holes, the size of the cells in the structurai matrix can be regulated. The exact size and number of vent holes depends on the sr~e ofthe article being produced Larger articles require more vent holes.
Examples of vent sizes and numbers to produce articles is shown later in the appiication in the Example Section. In the producion of most articles of the present invention the vent sizes will preferably range from about 0.05 mm2 to about 15 mm2, more preferably from about 0.2 mm- to about 5 mm-, and most preferably from about 0.5 mm2 to about 2 mm2 The number of vent holes will preferably be in a range from about I to about 10, wilh about 2 to about 8 being more preferred, and about 4 to about 6 being most preferred. In a preferred method for ~ r ~ ; e cups, it has been found that using 4 vent holes, each having a vent hole of about 1.9 mm~, is preferred.
Cyclic separation of the molds is used to produce articles having increased sicin thickness and density over a faster heating time. The step of cyciic separation is performed ~ afler the mixture is positioned between the molds and includes the repeated steps of slightly raising or separating the molds and then bringing them back together. By separating the moids, vapor is permitted to easily and quiciciy escape through the sides ofthe molds, as opposed to having to be forced through the vent holes.
Releasing the vapor helps to dry out the moldable material, which in turn increases the skin thickness ofthe reruiting artide. Onoe the step of cyclic separation is completed, the molds are locked and the process of forming the ceDular article is completed with the remaining amount of solvent in the mrb~ture.
As will be discussed later in greater detail, by decreasing the amount of solvent in the mixture through cvclic separation, the resulting article wiii have a higher density.
Cyclic separation also permits the solvent to escape at a faster rate, thereby yielding an article in a shorter period of time. However, if speed is the oniy ~ ;ll, the mixture can initially be made with less solvent, and thus lessen or eliminate the need for cyciic separation of the molds.
The variables associated with cyclic separation include the time the molds are open, the time the molds are closed between openings, the number of sPp ~ril~nc, and the distance the molds are separated. Depending on the desired properties of the articles, the time the molds are opened and the time they are closed during the cyclic separation (which do not have to be the same) are each in a preferred range from about 0.2 seconds to about WO 96/0s2s4 2 1 ~ 7 0 ~
~ i -,9 5 seconds, with 0.3 seconds to about l second being more preferred~ and from about 0.4 - seconds to about 0.7 seconds being most preferred The number of separations is typicaDy in a preferred range from about I to about 20. with about 3 to about 10 being more preferred, and about 4 to about 7 being most preferred. Finally, the separation distance 5 wJI preferably be within a range from about I mm to about 25 mm, with about 2 mm to about lO mm being more preferred. and about 3 mm to about 5 mm being most preferred.
As wiD be discussed later in greater detail, selected admixtures such as humectants or plasticizers can be added to the mixtures to impart desired flexibility to the article during the forming step. If no such admixtures are combined with the mixture, and as a lO result of the removal of ' "~ aD the solvent from the mixture, the article removed from the molds is often brittle and may be cracked or crushed. To instiD the necessary flexibility and J ~ before-cracking to make the article useful, moisture is~ ~JulaLt~ back into the starch-bound structural matrix. This process is referred to as g " The moisture is preferably applied by placing the article within a bigh 15 humidity chamber at a ~ d Lelll~ dLUlt and humidity. Moisture within the highly humid c...;.u~n~ is absorbed by the starch-based binder. The moisture softens the starch-based binder and increases the flexibility of the article. Since the starch-based binder has a natural aflinity for water, the anicle can be c.., l ;. ,...~.1 by simply exposing the anicle to normal .,...uu~ul.."lt~ conditions. Over time, the article will absorb moisture 20 from the air until it reaches a point of P~lui~ rj,.~ However, depending on the humidity in the air, such a process can take hours, days, or even weeks. r.,l Lll~l 1llOl ti, in very dry climates, there may be insufficient moisture in the air to adequately condition the anicle.
The use of a humidity chamber speeds up the process to within a matter of minutes, making it possible to mass-produoe the articles. The variables associated with the 25 humidity chamber include time, k.~ aLule, and humidity. Studies have found tbat higher humidities up to about 95% are preferred, as they decrease the amount of time necessary for the article to absorb sufficient moisture. It is preferred, however, that water not be directly applied to the anicle, nor should the humidity be so high that water condenses on the article. The application of water directly onto the surface of the article 30 can cause the starch-based binder to swell, thereby forming an irregularity on the surface - of the article. Accordingly, the humidity within the high humidity chamber of the present invention wiD preferably be in a range from about 50% to about 95~/0, with about 75% to about 95% being more preferred, and about 85% to about 95% being most preferred.Although increasing the lI,Ill~J~..dLUI t' in the humidity chamber also increases the 35 rate of absorption of moisture, if the anicle absorbs moisture at an excessive rate, the exterior will become unstable and lose its shape prior to the interior of the article obtaining .,, . :, ., . .. _ _ , . , WO 96105254 ~ J..3~ l 2197~5~ ~

the required moisture content. Fu.fi.~.l..v.~, it is difficult and expensive to obtain humidity chambers that can create an tll~;.U. Il~,UI having both high ~ u-~ and humidity. Accordingly, the ~ ,41UI~ within the humidity chamber will preferably be in a range from about 30~C to about 60~C, with about 35'C to about 55~C being more 5 preferred, and from about 40~C to about 50~C being most preferred.
The time in which the articles remain in the humidity chamber is, of course, dependent on the temperature and humidity level. ~ost articles obtain desired properties with a moisture content of less than about 20~/c by weight of the article. The present articles can be ~ ed having a moisture content preferably in a range from about 2% to about 20% by weight of the article, with about 2% to about 15% being more preferred, and about 4~/0 to about 10% being most preferred. As will be discussed later in greater detail, the required moisture content is in part dependenl on the r.. _. ,n Al i~
of inorganic fillers in the articles. The time period for an article to obtam the desired moisture content is also dependent on the thickness of the article. The thicker the article, 15 the longer it will take for the moisture to penetrate to the center ofthe article. The rate of absorption and the necessary moisture content to yield an article with the desired properties are also dependent on the type and quantity of filler, which will be discussed later in the section on aggregates.
From a heaAth standpoint, it is desirable to minimize the moisture content in an20 article, preferably to below about 10%. The lower the moisture content, the less chance of bacterial growth in the article and mold formation on the surface. This is especially important for food and beverage containers. , u. 1ll~l ...u. ~, absorbing too much moisture can cause the article to become unstable. Based on the above parameters for l.,...~w ~lu.
and humidity, the present articles are preferably left in the humidity chamber for a period 25 of time in a range from about 1 minute to about 30 minutes, with from about 5 minutes to about 15 minutes being more preferred, and from about 5 minutes to about 10 minutes beine most preferred. Such periods, however, can be extended for very thick articles and shortened for very thin articles.
Using the above processes in i., .j, 1;.... with the mixture ~ omr~ outlined 30 below~ cellular articles of the present invention are preferably manut~actured to have a density in a range from about 0.05 g/cm3 to about I g/cm3, with about 0.1 g/cm3 to about 0.5 g/cm3 being more preferred, and about 0.15 g/cm3 to about 0.25 g/cm3 being most preferred.
The remaining processing steps include optional steps, such as printing and~5 coating. These steps. along with stacking, bagging, and boxing, are performed '1~ identicaDy to that of cu..~,.liu.~l articles made from materials such as paper, .. . . .. ...

WO 961n5254 1 ~ " ,v..
13~ 91~"~

plastic, polystyrene foam, and other organic materials. These steps are discussed later in - the disclosure.

IV. CQMPOSITIONAL EFFECTS ON FORIUATION.
STo facilitate ;~ of the ~ V~il UvlU~ .; g approach. each of the , in the moldable mixture is discussed. The discussion includes the properties and preferred 1~ ulJul I iu~ of each of the c~ ~ u l~u~ ~ ~, aiong with how each component is interrelated with processing parameters, properties of the moldable mixture, and properties of the final article.
A. Sl,7. ~h I ~d Binders.
The moldable mixtures used to l.~uLvlul-v the ~ , filled, cellular articles of the present invenrion develop their strength properties through the gelation and subsequent drying out of I ' ".~, solvated starch-based binder. Starch is a natural 15 v.llbuhJv~ v chain comprising pol~.nv~ sugar molecules (glucose). Plants v and store the starch as food for itself and for seeds. Starch is formed in granules that comprise two types of glucose polymers: the single-chain amylose that is soluble in water and other solvents and the branched ...."lop~ that is insoluble in water.
20In general, starch granules are insoluble in cold water; however, if the outermembrane has been broken by, e.g., grinding, the granules can swell in cold water to form a gel. When the intact granule is treated with warm water, the granules swell and a portion ofthe soluble starch (amylose) diffuses through the granule wall to form a paste.
~ In hot water, the granules swell to such an extent that they burst, resulting in gelation of 25the mixture. The exact lvlllyv~ulv at which a starch-based binder swells and gelates depends on the type of starch-based binder.
Gelation is a result ofthe linear amylose polymers, which are initially, . vwvd within the granules, stretching out and cross-linking with each other and with the ~v.., !u~vvfi~ er the water is removed, the resulting mesh of inter-connected polymer 30 chains forms a solid material that can have a tensile strength up to about 40-50 MPa. The amylose polymers can also be used to bind individual aggregate particles and fibers within the moldable mixture (thereby forming a highly illw~ / filled matrix) Through 7 careful .. ,.v. u~l. UvlUIvl ~Ljn~Pnng, highiy a~vl~ filled containers and other articles can be designed having desired properties including flexural strengths up to about 8 MPa.
35Although starch is produced in many plants, the most important sources are seeds of cereal grains (e.g., corn, waxy corn, wheat, sorghum, rice, and waxy rice), which can .:.. .. ... . ... . . , . ... _ .. .. . _ _ _ . . .

W0 96/05254 P~,l/-J ,. .;
~1~7 ~S~ 32 also be used in the flour and cracked sta~e. Other sources include tubers (potato), roots (tapioca (.i.e., cassava and maniac), sweet potato, and arrowroot), and the pith ofthe sago palm.
As used in the ~ and the appended claims, the term "starch" or "starch-S based binder" includes unmodified starches (amylose and ~ .ylu~J~ ) and modifiedstarches. By modified, it is meant that the starch can be derivatized or modified by typical processes known in the art such as, e.g. e~klir.w.iUl., rl~ , oxidation, acid hydrolysis, cross-linking, and enzyme conversion. Typical modified starches include esters, such as the acetate and the hab~-esters of d;~,al L.UAyl;~, à~,iJ~ hJ 1~ id~,s, particularly 10 the " ~:s. ~i.~ ,;lJ h~ l,;d.,~, ethers, such as the hrL UA~ ~.llyl and hJI~ UAyyl U~J~
starches; oxidized starches, such as those oxidized with hy~.o..;.lu.iLe, starches reacted with cross-linking agents, such as 1 ' , ' u~ uAy~,.lul;dc, c~ u~uhJJ~ , hJIIOr~ ~ ' cationic epoxides, and phosphate derivatives prepared by reaction with sodium orpotassium u.i' ~' ~ ,' or Ll;yul~ u~lldt~" and ~.u ' ~ thereof. Modified 15 starches also include seagel, long-chain alk~l~LalLhLs, dextrins, amine starches, and dialdehyde starches. Unmodified starch-based binders are generally preferred over modified starch-based binders because they are s;~.;5callily less expensive and produce comparable articles.
Pre-g ' ' starch-based binders can also be added to the moldable mixture.
20 P~ Li-~.,d starch-based binders are starches that have previously been gelated, dried, and ground back into a powder. Since pre-g_L.i;.uLci starch-based binders gelate in cold water, such starch-based binders can be added to the moldable mixture to increase the - mixture viscosity prior to being heated. The increased viscosity prevents settling and helps produce thicker ceD walls as will be discussed later in greater detail. In such cases, 25 the pre-gelated starch-based binder might be considered to be acting as a rheology-modifying agent.
Preferred starch-based binders are those that gelate and produce a high viscosity at a relatively low ~ .,.dLul~. For example, potato starch quickly gelates and reaches a maximum viscosity at about 65 ~C. The viscosity then decreases, reaching a minimum 30 at about 95~C. Wheat starch acts in a similar fashion and may be preferred, depending on cost and availability. Such starch-based binders are valuable in producing thin-waDed articles having a smooth surface and a skin with sufficient thickness and density to impart the desired mechanical properties.
As previously discussed, the portion of the moldable mixture closest to the heated 35 molds is rapidly heated. By using a mixture containing potato starch, the portion ofthe moldable mixture closest to the heated molds is at a maximum viscosity during drying and W096/05254 21 9 7~ r~l~n , =

33 ~ ~
. .
formation of the ceDular structure. Accordingly, the cells near the sides of the article have - a minimum ceD size and a maxirnum cell vrall thickness. In contrast, the cellular structure in the moldable mixture at the interior section of the article is not fommed until after the viscosiry has decreased. As a result, the ceUs in the interior section are much larger. This 5 theory is consistent with the formation of the cellular matrix as previously described.
It may be preferred to combine different types of starch-based binders to regulate the cellular matrix. Tn contrast to potato starch, the viscositv of a mixture containing com starch gradually increases as the ~ ly~,~a~ulc increases. Accordingly, com starch produces a relatively low viscosity mixture compared to potato starch at 65~C, but 10 produces a relatively high viscosity mixture compared to potalo starch at 95~C. By combining both com starch and potato starch within the same mixture, ehe viscosity of the mixture at the interior section of the article is increased at the point when the ceDs are fommed. The increased viscosity decreases the ceU size and increases the ceU waUthickness, thereby increasing the fracture toughness of the article.
The f" ~ .... of starch-based binder within the moldable mixtures of the present invention are preferably in a range from about 10% to about 80% by weight of total solids, more preferably in a range from about 30% to about 70%, and most preferably from about 40% to about 60% by weight. Bu~ v ~ ~ ' of dif~ent starches may be employed to more carefully control the viscosity of the mixture 20 throughout a range of ~...ye. ,.t... 1,~, as weU as to affect the structural properties of the final hardened article.

B. ~olvent.
A solvent is added to the moldable mixture in order to lubricate the particles, 25 solvate or at least disperse the starch-based binder, and act as an agent for gelating the starch-based binder. A preferred solvent is water, but can include any liquid that can disperse and gelate the starch-based binder and be c~ u ~lly removed fomm the moldable mixture.
The amount of heat energy required to remove the solvent must be great enough 30 to overcome the boiling point of the solvent being used. Besides boiling at 100 ~ C, water - bas a relatively large heat of VGYUIi~liOll compared to most other solvents, including alcohols. Both the boiling point and the heat of ~"p ~ of water can be reduced tbrough the addition of alcohol co-solvents with the water. Alcohols, such as ethanol and isopropyl alcohol, are preferable because they fomm lower boiling point azeotropic 35 mixtures with water and are relatively inexpensive and readily available. Production costs may be optunized by using a mixture of water and alcohol as long as the benefits of using _ _ , . . . .. ... .. .. _ _ ... _ . _ . . = .

wo s6/0s2s4 r~ x7 alcohol co-solvents. such as the savings in time and energy, are not outweighed by the increased cost of the alcohol.
The solvent also serves the unctlon of creating a moldable mixture having the desired rheological properties, including viscosity and yield stress. These properties are 5 general ways of ~Ilu~lu~~ g rhe "~u ' ' ' .~" or flow properties of the moldable mixture. The viscosity of the mixtures of the present invention may range from being relatively low (similar to that of a thin batter) up to being very high (similar to paste or clay). Where the viscosity is so high that the material is initially moldable and dough-like in the green state, it is genaally betta to refa to the yield stress, ratha than the viscosity, 10 of the mixture. The yield stress is the amount of force necessary to deform the mixture.
As will be discussed later, the amount of solvent required to impart a certain viscosity and/or yield stress to the mixture is highly dependem on the packing density and specific surface area of the aggregate material. These are also dependent on the addition of admixtures, such as rheology-modifying agents and ~ perQ~nt~
At a minimum, a suflicient amount of the solvent should be added to disperse anduniformly gelate the moldable mixture. The solvent content should also be sufticient to function with the processing equipment. As will be discussed lata in 8reata detail, moldable mixtures with high viscosity and yield stress may require an auger apparatus to mix and convey the mixture to the mold. In contrast, low viscosity mixtures can use 20 ~,u,.. ul;u~d mixers to combine the ~n ~ and pumps to transfer the mixture.
lncreasing the solvent content also increases the number and size of the cells in the structural matrix and lowers the density of the resulting article. In theory, the more solvent in a mixture, the more vapor that is produced, and thus, the more cells that are formed. Fu,Lh~ u~, the more solvent in a mixture, the lower the viscosity of the2$ mixture, and thus7 the larger the size of the cells. However, the more solvent added to a mixture, the more time and energy required to remove the solvent, and thus7 the slower and more expensive the process. In addition, if the solvent content gets too high7 the mixture may be unable to produce form-stable, crack free articles. In contrast, using low water yields a more dense product having smaller cells.
Very low viscosity mixtures can also result in settling of the ~ , most notably the ungelated starch-based binder and aggregate particles. Settling may occur in the mixing stage, transfer stage, or forming stage. Settling can yield articles having varying properties from batch to batch or within the structural matrix of a single article.
F . l,. . ;,1 . ~ ' have also found that vay low viscosity mixtures can splash out of the female mold during mating with the male mold. This is especially true for shallow articles such as plates.

.. ... . ..........

WO 96105254 2 1 9 7 0 ~ g 3~ ~
Bzsed on the above discussion, the percentage of solvent in the mixture depends,- in parL7 on the processing equipment, the desired viscosity, and the desired properties.
The amount of so!vent added to the mixtures of the present invention will preferzbly be in a rznge from about 20% to about 70% by totzl weight of the mixture, more preferably from about 30% to about 60%, znd most preferably from about 40~/0 to about 50~/0.
As stated above, the viscosity of the moldable mixture is dependent on severai vzriables such as the water content, the presence of admixtures such as rheology-modifying agents znd dispersznts, whether the stzrch-bzsed binder has been pre-cooked, znd the packing densiy ofthe aggregate. Functional articles can be made from moldable mixtures having a large range of viscosities, from as low as about 0.05 Pa s to as high zs zbout 10'~ Pa s. Low viscosity mixtures czn be poured into the molding appzratus while high viscosity mixtures may be placed into the molds by auger or piston insertion.
Ful P c, high viscosiy mixtures having a Cul~ h,~,y similar to that of clay or dough can be cut into smzii portions which czn then be rrlf rh~if ~lly plsced between the molds.
In generzi. the moldable mixtures of the present invention will preferably have a viscosity in a range from about 0.01 Pa s to zbout 300 Pa sl more preferable from about 0.05 Pa s to about 30 Pa-s, znd most preferzbly from zbout 0.2 Pa s to about 3 Pa s. The rheology of the moldzble mixtures may aiso be described in terms of yield stress, which will preferably rznge up to about 500 kPa, more preferabiy up to about 300 kPa, znd most preferzbly up to about 100 kPa.

C. a~re~ateS.
The terms "aggregate" and "fillers" zs used in the ~ , and the appended claims include both inorgznic and inert organic particles but do not typicaiiy include fibers.
The term "inert orgznic particles" is further defined to include orgznic ~ that zre not intended to primzri.y chemicaily or ... ~ , act as a binding agent within the moldable mixture. Examples of inert orgznic pzrticles include seeds, grains, cork, and plzstic spheres. Although most aggregates within the scope of the present invention zre jnsoiuble in water, some zggregates zre s.ightly soluble in water, and some aggregates czn 30 be formed in situ by ~JIC~ J;Ldliull or ~ dLiu-~ ~However, many seeds contain starch, proteins, or other polymeric materials in high enough quantities that they may be released into the moldable mixture and impart a binding force within the mixture.) Articles with a high filler or aggregate content can be made having a lower cost, improved mechanical and structurzi properties, better health safety, znd minimal35 ~l~i.U.~ di impact. Studies have found that functionzi zrticles of the present invention czn be made using fillers up to about 90% by volume.

_ _ ,,,,, .. ..... ........ . ....... _ .. -. ---wo s6/0s2s4 ' . 36 From a materials cost stand point. it is more economical to replace the relatively expensive starch-based binder with a less expensive aggregate. Tvpically, the density and weight of an article increase with increased filler. As the density of the mixture increases, the volume of material used to make the article also increases. For example, holding all other variables constant, a 40~/0 increase in the .,-.".,~ dfiull of calcium carbonate results in about a 30% savings in the ~ " ~ of starch-based binder. It is believed that as the percentage of filler increases, however, the ability of the cells within the starch-bound matrix to expand is decreased, thereby increasing the density and requiring more material to make the same article Nc ~u. Ih~h~J~ even with the increase in density, it may be more 10 economicai to produce articles having a higher filler content compared to those having a relatively low filler content.
Increasing the filler is also beneficial from a processing standpoint. Starch has a natural affinity for water (the most common solvent used). Accordingiy, more energy is required to remove water from the starch-based binder than from a filler. By increasing 15 the filler content, there is less starch-based binder to absorb the water and less water is needed to gelate the starch-based binder. r~.. L~ l.u.c, more of the water is absorbed by the filler. Accordingly, processing costs are decreased by using high c~ u~l; offiller, since less soivent and energy is required to produce a form-stable article.
ru,i' c, the inorganic aggregate can aiso be used as a means for conducting heat20 quicker and more uniformiy throughout the entire structural matrix. As a resuit, form-stable atticles can be made quicker and with a more uniform cross-section. The ability of the aggregate to conduct heat is, of course, a function of the type of aggregate and can be selected by those skilled in the art.
By selecting an appropriate fiiler, the specific heat of the final atticle can also be 25 decreased. For example, articles made with calcium carbonate were found to have a lower specific heat than those that contain only starch. As a result, such articles can be used for heating up food or other items without s;~y,.fi.,~"~lly heating up the article. For example, the present articles can be used for heating up or cooking food in an oven or microwave without destruction of the article. By selecting fillers with low specific heat, the articles 30 of the present invention can be made having a specific heat in a preferred range from about 0.3 J/g K to about 2.0 J/g-K at a Ic~ tu~c of 20'C, with about O.S J/g-K to about l.S J/g K being more preferred. and about 0.7 J/g-K to about 1.0 J/g K being most preferred.
Increasing the fiiier content is also beneficiai in varying the shape of the structural 35 matrix of the article. .4s previously discussed, if insufficient moisture is removed from the mixture during formation of the article, the remaining solvent can cause the mixture to W0 96/0s2s4 2 ~ r~ c~
~ ~: . ' '' ' ';

stick to the mold and may aiso cause the article to crack or bubble. Likewise, the article - can aiso crack if too much moisture is removed from the mixture. There is, therefore, a margin of time (dependent on variables such as the heat of the molds and amount of solvent in the mix~ure) within which the articles should be removed from the heated molds 5 to prevent cracking or sticking of the articles. This margin of time becomes narrower as the ~ u,,~ A~ -' of starch-based binder within a moldable mixture is increased. As the margin of time for removai of the article from the mold decreases, it becomes more difficuit to ~ ura~,Lul ~i articles having cross-sections of varying thi~ l~n~cc~c That is, at times it may be preferred to increase the thickness at a specific section lû of an article to increase properties such as strength or insulation at that section.
However, heating the mixture for a sufficient period of time to remove the solvent from tne thick section may remove too much moisture from the thinner sections Thus, mrxhlres having a high. starch-based binder content are typicaiiy iimited to the ...~u.uL~
of articles having a more uniform cross-section.
In contrast, studies have found that as the percentage of inorganics increases and the percentage of starch-based binder decreases, the margin of time in which the articles can be removed form the molds without sticking or cracking increases. As a result, articles having a high, of inorganics can be used to more effectivdy ~ articles having varying cross-section thickness. A ticles have been made in 20 which the thickness of the article varies by a factor of three.
There are also health benefits to using highe m ~ m~ .~ of filler. Increasing tbe amount of aggregate or filler in a mixture decrease the amount of water needed to be absorbed by the arricle during the i " g stage to obtain the desired properties. As previously discussed, minimizing the amount of water in an article is preferred since, it 25 mil~imizes the chance for bacterial growth. Studies have found that the more calcium carbonate in a mixture, the slower the moisture is absorbed by the article in the ~ ~, sLage. It was also discovered that the more calcium carbonate in a mixture,the less moisture needed to be adsorbed by the article to produce the same properties.
Accordingly, increasing the filler content decreases the required moisture content in the 30 final product, as well as the propensity of the article to absorb even more water from the atmosphere.
By selecting the type of filler used. the properties of the filler can be transferred ~ to the finished article. The aggregate materials employed in the present invention can be added to increase the strength (tensile modulus and, especially, ~ J~ strength),35 increase the modulus of elasticity and elongaion~ decrease the weight, and/or increase the insulâtion ability of the resultant ;..~ ,all~ filled article. In addition, plate-like ... .. . . .. = ... ~ .. _ . . . . _ . ~ ~ i .

W0 9610i52~4 19~ O S 9 aggregates. such as mica and kaolin, can be used in order to create a smoother surface fLnish in the articles ofthe present invention. TypicaDy, larger aggregates. such as calcium carbonste, give a matte surface, while smaller particles gi- e a glassy surface.rinally~ there are also environmental benefits to having a high filler content.
5 Articles with high filler contents are more easily ~ iosed back into their natural ;, thereby minimizing visual blight. r... Lh.,. ~..ol ~ minimizing the starch-based binder reduces the amount of water that is consumed in the growing of starch-bearing plants.
Particle packing is a preferred process that can be used to maximize the amount 10 of inorganics within the mixture and thus optimize the above discussed properties.
Studies have found that the packing density of a mixture is increased where two or more types of aggregate hzving a difference m their average particle size diameter are used.
Particle packing is the processes of selecting different sizes, shapes, and: - r of the aggregates to minimize the interstitial space between the particles and maximize the 15 packing density. By minimizing the interstitial space, less solvent and starch-based binder needs to be added to the mixture to fill the interstitial space.
To form an article having a more form-stable, crack-firee structural matrix, thestarch-based binder must usually be added in an amount sufficient to bind the aggregate together. As previously discussed, the mixture is prepared by combining an inorganic 20 aggregate with a solvent and starch-based binder. The solvent disperses the starch-based binder and controls the viscosity. During the forrnation process, a majority of the solvent is removed. The volume of solvent and starch-based binder that remains within the final article must be sufficient to coat the aggregate particles and fill the interstitial voids between the particles so that the starch-based binder can bind the aggregate particles 25 together.
If insufficient quantities ofthe starch-based binder are added, minute pores form between the aggregate particles. These minute pores are different from the cells which are preferably designed within the structural matrix. Whereas the ceDs result from the expansion of the solvent during the processing step, the pores result from an insufficient 30 amount of starch-based binder to bind the aggregate particles together. If the volume of starch-based binder is further decreased, the volume of the binder becomes so minute that either the structural matrix will crack during the formation process or the mixture will never consolidate into a form-stable article.
The ability of the starch-based binder to hold the aggregate particles together iS
35 a function of its intrinsic bond strength, covering power, and its ability to bond with the surface of a particular material. In the ~u~l.ur~lul ~ of articles in which a binder matrix .. _ , ..... . .

WO 96AI5254 , r~
g holds together a very large ~,u~.-c~aldLu~ll of matter, the binder preferably envelops each - of the matter particles. If the matter to be held together has a relativelv high surface area, then the amount of binder r~equired ro envelop the matter particles increases. That is, the rafio of binder to matter increases as the specific surface area of the matter increases. In 5 the present invention, it is of ren preferable to select an aggregate ma~erial having lower specific surface area in order to reduce the binder to matter ratio. In addition, as explained more fully below, increasing the particle packing density of the aggregate material also decreases the amount of binder needed to fully envelop the aggregate particles. An ll~dL~ dlld;llg of the interaction between particle size dictnh~tinn~ the 10 particle packing density, specific surface area, and binder volume is at the core of the successful loading of relatively high levels of inorganic solids within the starch-bound matrix.
In addition to specific surface area, the volume of starch-based binder required is related to the volume of rnterstitial space between the particles. The volume of intersitial 15 space increases in a mixture as either the packing density of the aggregate decreases or the percentage of the aggregate in the mixture increases. According:ly, by holding the ~.~.. ,.. 1;.. of starch-based binder and aggregate constant by weight of the solids within a mixture and decreasrng the packrng density of the aggregate, the interstitial space will increase to a point in which the volume of starch-based binder is insufflcient to 20 adequately fill the interstitial space. Likewise, by adding a higher ~iull~ aLu~ of aggregates, although the percentage of interstitial space remains relatively constant, the total volume of interstitial space increases. As a result, more starch-based binder must be added to the mixture to adequately Sll the spaces. As more starch-based binder is added, however, the v . ~ . . of inorganics decreases in the final articles, thereby increasing 25 the cost and minimizing the above discussed benefits.
In contrast, as the packing density ofthe aggregate increases, the interstitial space between the particles decreases. As a result, less starch-based binder and solvent are needed to fill the interstitial space. By decreasing the amount of starch-based binder to only the minimum amount needed to bind the aggregate particles and impart the desired 30 physical properties, the percentage of inorganics in the final articles may be increased - without sacrificing the desired strength and rheological properties. As such, the cost of the articles is decreased and the above discussed properties are enhanced.
The volume of starch-based binder required is also dependent on the size and shape of the aggregate. Aggregates having a large specific surface area compared to 35 aggregates of equal volume having a smaD specitic surface area require more starch-based binder to coat the particles. Coating the aggregate with the gelated starch-based binder WO 961052s4 ~19~5~ ~

is necessary to bind the aggregate together. In addition. the greater specific surface area ufilizes more of the available wa~er wilhin the mixture in the coating of the particle surfaces, resulting in less water being available Ic reacl wilh and gelate the starch Accordingly, in order to maximize the inorganucs and minimize the volume of S starch-based binder, it is preferable for the aggregates to have a smaller specific surface area. The highly illUlo ' "~ filled articles of the present invention preferably employ aggregates having a specific surface area in a range firom about 0.1 m2/g tû about 400 m2/g, with about 0.15 m2/g to aboul 50 m2/g being more preferred, and about 0.2 m2/g to about '.0 m~/g being most preferred. Particles having a relatively small specific surface area Iypically have a large average diameler and are spherical in shape.
For a mixture lo obtain the desired viscosity to form an article, the solvent must be added in an amount sufficient to coat aD of the particles and fill all remaining imerstitial space bet veen the particles. The interstitial space relevant to the solvent include the spaces between the aggregates and also between the any remaining ungelated starch granules. Even with the interstitial space filled with solvent, however, the mixture stiD
may have a relatively high viscosity. To obtain a desired lower viscosity, an additional amount of solvent must be added to the mixture. That is, it is the amount of solvent added beyond what is necessary to coat the particles and fill the interstitial space that actually provides the lubrication between the surfaces of the particles.
The foDowing iDustrates how increasing the packing density decreases the amount of solvent and starch-based binder needed to fill the interstitial space. If the particle packing density ofthe moldable mixture is û.65, a solvent will be included in an amount of roughly 35% by volume in order to ' "~v fill the interstitial voids between the particles. On the other hand, a moldable mb~ture having a particle-packing density ûf 0.95 wiD only require solvent in an amount of about 5% by volume in order to ! I ' " "~ fiD
the interstitial voids. This is a seve~-fold decrease in the amount of solvent which must be added in order to ' "~, fiD the interstitial voids. Reducing the amount of solvent that would otherwise be required to fill the interstitial space permits the articles to be made more quickly and with a lower energy ~.~, ~..,.~1.l;....
In order to optimize the packing density, differently sized aggregates with particle sizes ranging firom as smaD as about 0.05 llm to as large as about 2 mm may be used. To maximize the strength ofthe ceD waDs, it is preferred that the particles not be greater then 1/4 the thickness of the cell walls. Spherical particles having minimal fractured surfaces are preferred, since they can be packed to a higher density and have the lowest specific surface area. In order to obtain an opfimized level of particle packing, it is preferable for the average particle size within one size range to be roughly 10 times the particle size of ,, . . _ . , . _ 4 ~! 1 T 7 ~ 5 9 1 i 5 _ r ~ IJL _ _.

, the next smallest particle range. (In many cases. the ratio will differ and is depcndent on - the relative natural packing densities of the different aggregates Io be combined.) For example, in a two-compor.enT system. it will be preferable r'or the average particle size of the coarse component to be at about ll~ times the average particle size of the fine component. Likewise. in a three-component system, it will be preferable for the average particle size of the coarse component to be about 10 times the average particle size of the medium component, which will likewise preferably be about 10 times the size of the fine component. I~T~ . _ Lh~ ~, as more differently sized particles are added, the ratio between the particle size magnitudes need not always be this great and may only be two-fold in some cases.
ID general, a two-component (or binary) packing system will seldom have an overall packing density higher than about 80%, while the upper limit for a th~
component (or ternary) system is about 90%. To obtain higher particle packing it wiU be necessary in most cases to add four or more ;~~~, although having broader and more optimized particle sizes among two- or three-component systems can yield higher overaU particle pac. ing than 80% and 90%, . ~p.,~
For example, in a three-component system, it has been found preferable for the fne aggregate particles to have diameters in a range from about 0.01 llm to about 2 um , for the medium aggregate particle to have diameters in a range from about I ,um to about 20 ,um, and for the coarse aggregates to have a diameter in a range from about 100 ~m to about 2 mm. In a two component system, any two of these ranges may be preferable.
Irnproved packing densities for the aggregate can be obtained by physically combining different sizes and amounts of aggregates and then using ,,u.... ' testing methods to determine the ~ ' of aggregates that has the highest packing density.In light ofthe possible I however, such a process is very time consuming and does not necessarily provide the best results. In the preferred - ~l o l d the aggregates are selected to obtain a desired packing density based on the particle packing process as disclosed in the following article coauthored by one of the inventors of the present invention: Johansen, V. & Andersen, P.J., "Particle Packing and Concrete Properties,"
- M ' Srirnrr of Concrete II at 111-147, The American Ceramic Society (1991).
Further rnformation 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. The preferred process of particle pac. ing is also discussed in detail in United States Patent Application No. 08/109,100, entitled "Design Optimized C-~ o- ~ - and Processes for Mi, .-l~L~ , r ~ ~

W096/05254 , ~ , r~".,~
2~97 ~S~ 47 ~'~m~mitir~lc Mb~tures". to Per Just Andersen and Simon K. Hodson. filed on August 18, 1993. For purposes of disclosure. the foregoing articie~ doctorai dissertation, and patent application are ;...,u. ~JUl dLcJ herein by specif c reference.
The above references teach the use of n~-~h ~ 1 models to determine the 5 ~ ' of defned groups of particles that will result in the maximum packing density. The models are based on the average diameter size and natural packing density for each type of aggregate. In general, the combined particle packing density for the aggregate mixture wiii preferably be in a range from about 0.65 to about 0.99, more preferably from about 0.~0 and about 0.95, and most preferably from about 0.75 and about 0.90. (The added cost of achieving 99% particle pacicing efficiency is often prohibitive; therefore, most preferred pacicing densities are somewhat less).
There are a variety oftypes of aggregates that can be used in the present invention.
Inorganic materials commoniy used in the paper industry, as well as more finely ground aggregate materiais used in the concrete industry, may be used in the moldable mixtures of the present invention. The size ofthe aggregate or inorganic filier wiii usuaiiy be many times greater than the inorganic filier materiais typicaily used in the paper industry.
Fxamples of useful aggregates include perlite, vermiculite, sand, gravel, rock limestone, sandstone, giass beads, aerogel, xerogels, seagel, mica, clay, synthetic day, aiumina, siiica, rdy ash, fused silica, tabular aiumina, kaoiin, ~ ui~JL~ holiow giass spheres, porous ceramic spheres, gypsum (calcium sulfate dihydrate), caicium carbonate, calcium aiuminate, lightweight polymers, xonotlite (a crystalline calcium silicate gel), iightweight expanded clays~ hydrated or unhydMted hydraulic cement particles, pumice, exfoiiated rocic, and other geologic materiais. Partiaily hydrated and hydrated cement, as weii as siiica fume, have a high surface area and give excellent benefits such as high initiai ' . ~ ., of the freshiy fommed article. Even discarded ~ fiiled rnateriais, such as discarded containers or other articles of the present invention can be employed as aggregate fillers and sllt..y,ih~..",.~. It wili also be appreciated that the containers and other articles of the present invention can be easiiy and effectively recycled by simply adding them to fresh moldable mixtures as an aggregate filler. Hydraulic cement can aiso 30 be added in either its hydrated or unhydrated fomm.
Both clay and gypsum are particularly important aggregate materiais because of their ready avaiiabiiity, extreme low cost, workability, ease of fommation, and because they can aiso provide a degree of binding and strength if added in high enough amounts (in the case of gypsum hemihydrale). Because gypsum h~,., h~dl~Lc can react with the water 35 within the moldable mixture~ it can be employed as a means for holding water intemaily within the molded article.

WO 9G/05254 ~ 5 ~ F.~ c ~ ~ ~ , . 4 In some cases, it may be desirable to torm ettringite on the surface of the ~ aggregate particles in order to improve the interaction abd bond interface between the aggregate particles and the starch-based binder.
Because of the nature of the moldable mixtures and articles made therefrom, it is 5 possible to include lightweight aggregates having a high amount of interstitiai space in order to impart an insulation effect with the molded articles. Examples of aggregates which can add a lightweight ~,Lala~,Lcli~L;c and higher insulation to the molded articles include periite~ vermiculite, glass beads, hollow glass spheres, synthetic materiais ~e.g., porous ceramic spheres, tabular aiumina, etc.), cork, pumice, and lightweight expanded 10 clays, sand, gravel, rock, limestone, sandstone. and other geologicai materiais.
Porous aggregates can aiso be used to remove unwanted air bubbles from the article during formation. Solvents escape from the moldab~e mixture by first traveiing to tbe surface of the molds and then traveling along the mold surface to the vent hoies. At times, air bubbles get trapped between the maie mold and the outside surface of tbe 15 article, thereby pocicing the surface. A porous aggregate within the moldable mixture can be used to absorb a significant porLion of this enrrapped gas, thereby helping to reduce the incidence of pocking. Of course, the entrapped gas bubbles can be removed through the application of a vacuum.
Porous, lightweight aggregates, including zeolites, can be used as a means for 20 . ' _ the article during the forming process. Porous aggregates can be presoaked in a solvent or heid in the mixture for a sufficient period of time to absorb the solvent. As the mixture containing the presoaked aggregate is heated to form the article, the solvent is released more slowly from within the porous aggregate than from the remainder of the rnixture. As a result, a portion of the solvent wiil remain within the porous aggregate in 25 the form-stable article. Once the article is formed and removed from the heated molds, the solvent within the porous aggregate can diffuse into the :>UI ~ ~ '- _ structurai matrix, thereby l ' _ and sofLening the structurai matrix.
In addition to ~ull~s~L;~lllai aggregates used in the paper and cement industries, a wide variety of other aggregates, including metals and metal alloys (such as stainiess 30 steel. iron, copper, silver, and gold), bails or hollow spherical materials (such as giass, polymeric, and metals), filings, and pellets can be added to the mixture.
Another class of aggregates that may be added to the h~o-O ~ ".~, fiiled mixtureincludes gels and microgels such as silica gel, caicium siiicate gel, aiuminum silicate gel, and the iike. These can be added in solid form as any ordinary aggregate materiai might, 35 or they may be plc~,;tJ;LaLc i in situ. Because they tend to absorb solvents, they can be . .
... . . :. . , .. . . ... . . .. . . . . . . . . ... . . .. _ _ _ _ . .

wo 96105254 added to reduce the solvents content (Which will increase the viscosity and yield stress) of the moldable mixture.
In addition. the highly L~y v ,.,u~.;., nature of silica-based gels and microgels aUows them to be used as moisture regulation agents within the final hardened article. By~ absorbing moisture from the air. the gels and microgels will cause the articles to retain a amount of moisture under normai 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 articles allows for more careful controi of the elongation, modulus of elasticity, bendability, foldability, flexibiiity, and ductiiity of the 10 articles. Other moisture retention admixtures, such a MgCI2, are discussed more fuiiy below.
It is aiso within the scope of the present invention to include poly.,..,.i~le inorganic aggregate materiais, such as poly~ .i~vG~ siiicates, within the moldable mixture. These may be added to the mixture as ordinary siiica or siiicates, which are then 15 treated to cause a poly..,~ iu.. reaction in situ in order to create the polJ...~,.i~;i siiicate aggregate. Puly ' inorganic aggregates are often adv~hlt..b_~Ju~ in certain I;o.~ because of their increased flexibility compared to most other inorganic aggregate materiais.
The thermai ~ ' .;.y or "k-factor" (defined as W/m K) of the present articles 20 can be selected by controlling the cellular structural matrix. Articles can be made having a low k-factor by having a higher ~.o~ Y~ of celis within the structurai matrix. In .d,~ in which it is desirable to obtain a container or other article having an even higher insulation capabiiity, it may be preferable to incorporate into the highiy inu~ filled matrix a lightweight aggregate which has a low thermal '~ y.
25 Generaiiy, aggregates having a very low k-factor aiso contain large amounts of trapped interstitiai space, air, mixtures of gases, or a partial vacuum which aiso tends to greatly reduce the strength ûf such ag~regates. Therefore, concerns for insulation and strength tend to compete and should be carefully balanced when designing a particular mixture.
Preferred insulating, Gghtweight aggregates include expanded or exfoiiated 30 vermicuGte, perGte, caicined ' earth, and hollow glass spheres aG of which tend to contain large amounts of incorporated interstitial space. However, this list is in no way intended to be exhaustive, these aggregates being chosen because of their low cost and ready availability. N., ~._ I,.el, ~, any aggregate with a low k-factor, which is able to imparL sufficient insulation properties to the container or other article, is within the scope 35 ofthe present invention. In Gght of the foregoing, the amount of aggregate which can be added to the moldable mixture depends on a variety of factors, including the quantity and Wo 96105254 _ r~
9, ~

types of other added -- r as well as the particle packing density of the aggregates - themselves. By controlling the cellular structure and the addition of lightweight aggregate articles can be made having a preferred k-factor in a range of about 0.03 W/m-K to about 0.2 Wlm-K. Insularing articles can have a more preferred k-factor in a S range of about 0.04 W/m K to about 0.06 Wlm K. Nu.. ~ hlg articles can have a more preferred k-factor in a range of about 0.1 W/m K to about 0.2 W/m K.
The inorganic aggregates will preferably be included in an amount in a range from about 20% to about 90% by weight of the total solids within the ;..VI~ filled moldab!e mixture, more preferably in a range from about 30% to about 70%, and most 10 preferably in a range from about 40% to about 60%. The inert organic aggregates will preferably be included in an amount in a range from about 5% to about 60% by weight of the total solids, more preferably in a range from about 15% to about 50%, and most preferably in a range from about 25% to about 40% by weight. Lightweight aggregates, defned as those having a density lower than about I g/cm3, are preferably included in an 15 amount in a range from about 5% to about 85% by volume of the ~ filled moldable mixture, more preferably in a range from about 15% to about 65%, and most preferably in a range from about 25% to about 55% by volume.
As set forth above, differently sized aggregate materials rnay be added in varying amounts in order to affect the particle-packing densitv of the moldable mixture.20 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 than the sum of the volumes of the aggregates before thcy were mixed.

D. ~ 'd P.r' _A~ents.
To assist in removing the form-stable article from the molds, a mold-releasing agent can be added to the moldable mixture. A preferred mold-releasing agent is magn~Ci~lm stearate. M~grl~ ci~lm stearate functions as a lubricant and emulsifier and is well known as an anti-caking agent that is insoluble in water. On a more general scale, medium- and long-chain fatty acids, their salts, and their acid derivatives can be used as ~ mold-releasing agents. The preferred medium and long chain fatty acids typically occur in tbe production of vegetable and animal fats and have a carbon chain greater than C,~.
The most preferred fatty acids have a carbon chain length from Cl6 to C~. The fats and salts used herein need not be in a pure form but merely need to be the ~
cnmpo~ t That is, the shorter or longer chain length fatty acids, as well as theCUII~ JUlld~;-lg ~ fatty acids, can still be present ........... ; ~.. :. .~'.4.. .. ... _ .. ~_ ' ... ,______.:. ____ __ __ _. .

wo s6/os2s4 , F~l/~J.,,~.
5 g Various waxes, such as paraftin and bees wax, and Tefon-based materials can alsobe used as a mold releasing agent. One of the added benefits of using wax is that it can also act as a coating material. as discussed later. Other materiais, such as CaS, calcium silicate and Lecithin, have been found to work as mold releasing agents. To further assist S in releasing the articles from the molds, the molds can be polished, chrome plated, or coated with~ e.g.1 nickel, Teflon, or any other material that limits the tendency of the article to stick to the molds.
The above mold releasing agents are preferably added to the mixture in a ranye from about 0.05% to about 15% by weight of the total solids, more preferably in a range from about 0.1% to about 10%, and most preferred in a range from about 0.5~/c to about 5~/c.

E. Fibers.
As used in the ~ , and the appended claims, the terms "fibers" and 15 ~fibrous materials" include both inorganic fibers and organic fibers. Fibers have ~u~ ruliy been i~,ul~vu~lL~id mto brittle materials, such as ceramics, to increase the cohesion, elongation ability, deflection ability, toughness, fracture energy, and flexural, tensile, and, on occasion, CUIII~ strengths of the material. In general, fibrous materials reduce the likelihood that the hiyhly i ,, ".~ filled containers or other 20 articles will shatter when cross-sectional forces are applied. Although fibers have been found useful in increasing these properties in the articles of the present invention, their success has been limited.
As was previously discussed, the formed ar~icles of the present invention have afoamed or cellular structural matrix. As a result, there is a limited amount of mterfacial 25 surface area for load transfer between the fibers and structural matrix. That is, the fibers are coMected to the structural matrix of the formed articles only by the walls dividmg the cells. The remainder of the fiber is suspended in the cell. In some cases, the fibers are small enough to reside within the cell. As a result of the minimal contact betwoen the fibers and the structural matrix of the article, only a limited portion of the properties of 30 the fibers are hl~ul~Jul~i~cd into the structure matrix.
Fibers which may be i.,cul~JolaLcd into the invl~ filled matrix preferably mclude naturally occurring organic fibers, such as cellulosic fibers extracted from hemp, cotton, plant leaves, sisal, abaca, bagasse, wood (both hard wood or soft wood, examples of which include southem hardwood and southern pine, respectively), or stems, or35 inoryanic fibers made from glass, graphite, silica, ceramic, or metal materials.

w096105254 21 g 7~9 ~

4~
Recycled paper fibers can be used, but they are somewhat less desirable because - of the fiber disnuption that occurs during the original paper ~ - -,, r~ process. Any equivalent fiber, however, which imparts strength and flexibility is also within the scope of the present invention. The only limiting criteria is that the fibers impart the desired 5 properties without adversely reacting with the other ~ 1- ~ of the L ' 'Ismaterial and without f~ , the materials (such as food) stored or dispensed in atticles made from the material containing such fibers. For purposes of ilustration, sisal fibers are available from Llt.,~ L;u~ I Filler~ abaca fibers are available from Isarog Inc. in the Philippines, while glass fibers, such as Cemfillr, ate available from Pilkington Corp.
10 inEngland.
Studies have found that fibers having a relatively higher diameter or width are more effective in increasing the energy to failure and the t~ to failure. For example, sisal fibers having an average diameter of about 100 ,um were far more effective in increasing the above properties then the wood fibers having an average diameter of 10 15 u m. The addition of the sisal fibers also ' ''.S, decreased the stiffness in the dry cups.
Larger diameter fibers result in less surface area than smal diameter fibers of equal volume. As the exposed surface area of the fiber decreases, less solvent is adsorbed by tho fibers, and, accùl ," I~,~.y, the solvent is removed quicker with less energy. The fibers 20 used in the present invention preferably have an average diameter in a range from about 10 um to about 100 ,um, with about ~0 ,um to about 100 llm being more preferred, and about 75 ~m to about 100 ?,lm being most preferred. r.,. ~h.,~ ul~:, the fibers should have an average aspect ratio (length-to-width ratio) of at least about 10:1.
The amount of fibers added to the moldable mixture will vary depending upon the 25 desired properties of the final product. The flexurai strength, toughness, flexibi ity, and cost are the principle criteria for d~ ,, the amount of fiber to be added in any mix design. The~, t :.~li...offiberswithinthefinalhardenedarticlewillpreferablybein the range from about 0.5% to about 60U/o by volume of the totai solids content, more preferably firom about 2% to about 40%, and most preferably from about 5% to about 30 20%.
- Fber strength is a, .". 1~l. ?~ in determining the amount of the fiber to be used.
The greater the flexura. strength of the fiber, the less the amount of fiber that must be used to obtain a given flexural strength in the resulting a?ticle. Of course, while some fibers have a high flexural, tear and burst strength, other types of fibers with a lower flexural :~5 strength may be more elastic. A ' oftwo or more fibers may be desirable in wo s6/0s2s4 Y~ J
2~9~ oS9 order to obtain a resulting product that maximized multiple ~ n ;~ , such as higher flexurai strength, higher elasticity, or better fiber placement.
It should also be unders~ood that some fibers, such as southern 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 flexibiiity, and higher tear and burst strength are desired, a ~ of fibers having varying aspect ratios and strength properties can be added to the mixture It is icnown that certain fibers and inorganic fillers are able to chemicaiiy interact with and bind with certain starch-based organic polymer binders, thaeby adding another dimension to the materiais of the present invention. For example, it is icnown that many fibers and inorganic fillers are anionic in nature and have a negative charge. Thaefore, in order to maximize the interaction between the organic binder and the anionic fibers and inorganic materiais, it may be ad~ ~ to add a positively charged organic binder,such as a cationic starch.
1~ Betta water resistance can be obtained by treating the fibers with rosin and aium (Ai2(SO~)3) or NaAi(SO~)2, the latter of which precipitate out the rosin onto the fiber surface, maicing it highiy h,.' ~, ' ' The aiuminum floc that is formed by the aium creates an anionic adsorption site on the fiber surface for a positively charged organic binder, such as a cationic starch.
Ftnaiiy, the fibers may be coated with a variety of substances in order to improve the desired properties ofthe finai product. For example, the fibers may be coated in orda to make them more resistant to water absorption. In addition, ettringite can be formed on the surface of the fibers in order to improve the interaction or interface between the fibers and the starch-based binder.
2'3 F. J~ lodifvinv A~ents.
Rheology-modifying agents act to increase the viscosity or cohesive nature cf the moldable mixture. As previously discussed, increasing the viscosity decreases the size of the ceDs and increases the size ofthe ceD walls within the structural matrix. The resuiting article is thus denser and has a higher strength. Increasing the viscosity is aiso used to prevent settiing ofthe aggregates and starch-based binder within the mixture. Aggregates and unEelated starch granules have a natural tendency to settle in low viscosity mixtures.
As a result, during the time period between the preparation and heating of the mixture to the point of gelation, the aggregate and anv ungelated starch granules may begin to settie.
thereby producing an article having non-uniform properties. Depending on the density of W0 96~ 4 2 1 9 7 0 ~ 9 49 - ~
the aggregate, one of ordinary skill in the art can seiect the type and amount of rheology-- modifying agent to be added to the mixture to prevent settGng.
A variety of Datural and synthetic organic rheology-modifying agents may be usedwhich have a wide range of properties, including viscosity and solubility in water The 5 various rheology ..loJ;r~ll.g agents ~ , ' ' by the present invention can be roughly organized into the following categories: (I) cellulose-based materials and derivatives thereof, (2) proteins and derivatives thereof, and (3) synthetic organic materials.
Suitable cellulose-based rheology-modifying agents include, for example, J ~lluA~.,LtlJ.celluluse, h~l. uAy~ Lhr~ .ulùse~ ca buAy ,!~ ,e, lû n.~,Lll~k,elluloxi, dllyl~ell~llos~ L~llu~ "h~l~,ell~llust, llyJluAy.. llJl~luy~lu~.Lulosc, h, ' UA~!II ul~r!ul~ hfLeLlu~c, etc. The entire range of possible p~ l;u-- ~ is enûrrnous and shall not be Gsted here, but other cellulose materials which have the same or similsr properties as these would also work well.
Other natural pol~L.,lla.ide-based rheology - ~ ~L~~ agents include, for example, algrnic acid, I)hyuùcûllo;J~, agar, gum arabic, guar gum, loçust bean gum, gum karaya, and gum tragacanth. Suitable protein-based rheology-modifying agents include, for example, Zein~ (a prolarnine derived from corn), 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 ILeUIOgS ~luJ;r~G~o agents that are water dGspersible include, for example, polyvinyl ~ , pol1".h,'~,l._ glycol, polyvinylalcohol, pOIy~;~l ' '' yl ether, polyacrylic acids, polyacrylic acid salts, polyvinyl acrylic acids, polyvinyl acrylic acid salts, pul~ ' ' , ethylene oxide polymers, polylactic ~ acid, and latex (which is a broad category that includes a variety of pc,1~ .i4~1u substançes formed in a water emulsion; an example is styrene-butadiene çopolymer).
Synthetic organic polymers, especially the polyvinyl, , ', are also used as filmbinders to produce a hyJIu~llub;c surface on the starch-based binder. The LyJI~ . ' ' surface slows down the rate of water absorption by the starch-based binder in the mixing process, thereby permitting quicker formation of form-stable articles.
Rheology-modifying agents within the moldable mixtures of the present invention - are preferably included in an amount such that a hardened article will contain from about 0.5~/0 to about 20% rheology-modifying agent by weight of article, more preferably from ~ about 1% to about 10%, and most preferably from about 2% to about 5%.

.

W096105254 T~ .. ''t 2~,91~59 ~jQ
G. Di~
The term "dispersant" shall refer in the ~ and the appended claims to the class of materials which can be added to reduce the viscosity and yield suess of the moldable mixture. A more detailed description of the use of dispersants may be found in 5 the ~aster's Thesis of Andersen. P.J., "Effects of Organic Sui.~,. I 'a ~ Admixtures and their (~r -lr on Zeta Potential and Related Properties of Cement Materiais"
(The Pe.~ State University Materials Research Laboratory, 1987). For purposes of disclosure, the foregoing Master's Thesis is h~,mi~u~ d herein by specific reference.
Dispersants generally work by being adsorbed onto the surface of the sggregate I û par~icies and/or into the near colioid double layer of the particles. This creates a negative charge on or around the surfaces of the particles causing them to repel each other. This repulsion of the particles adds "lub, ;.,~tif..l" by reducing the friction or attractive forces that would otherwise cause the particles to have greater interaction. Tbiis mcreasès the packing density of the material somewhat and aliows for the addition of less solvent while 15 1 ~ the workability of the moldable mixture. Dispersants can be used to create iow viscosity, workable mixtures having a low f u~ of solvent. Such mixtures are suited for the production of high density articles.
Due to the nature of the coating mechanism of the dispersant, the order in whichthe dispersant is added to the mixture can often be important. If certain water-dispersible 2û organic po1ymer rheology-modifying agents (such as Tyiosel) are used, the dispersant should be added to a mixture containing water and at least part of the inorganicaggregates first and then the rheology-modifying agents should be added second.
Otherwise, the dispersant wili be less able to become adsorbed onto the surface of the aggregate particles because the TyloseL wili first be irreversibly adsorbed, thereby fonning 25 a protective colloid on the suri'ace and thereby preventing the dispersant from being adsorbed.
A preferred dispersant is polyacrylic acid. Another dispersant which can also work weD is meta phosphate. The amount of added dispersant will generally range up to about 5~/O by weight of the solvent, more preferably in the range from about 0.5% to about 4%, 30 and most preferably within the range from about l% to about 2%.
The dispersants l ,~ d within the present invention have sometimes been referred to in the concrete industry as "~u~ ul~iLi~ .. a. " In order to better distinguish dispersants from other rheology-modifying agents, which of len act as p~-..tiri7f.~i, the term "au~ ." will not be used in this , wo 96105254 ~ ~ ~ 7 ~ ~ 9 ~? r . ,.

H:. Other ~' ....
A variety of other ~ can be added to the moldable mixture to impatt desired properties to the final atticle. For example, enymes such as caluutl~dlao_, amylase, and oxidase produce holes in the surface of statch _ranules permitting the statch-5 based bindet to geiate faster in the case where ungelated statch is used. As a result, theviscosity of the mixture incteases al a faster rate. thereby producing arhcles with a sttonger and more unifotm cell sttucture.
Articles can 0itiaiiy be formed having a desired flexibiiity (as opposed to obtaining flexibiiity thtough the use of a humidity chamber) by adding ~ r that wiii tightly 10 bind the water within the starch molecules. This can be achieved with the addition of or .1- 1: I'J - 7-'1 chemicais, such as MgClD CaCI2, NaCI, or caicium citrate.
Because ail of these chemicais ate readily water soluble, they ate able to disttibute and retain water within the starch molecuies to provide a more uniform distribution of moisture. In turn, the moistute improves flexibiiity.
Fiexibiiity can aiso be obtained by addinB softenets or plasticizers to the moldable mixture. Such plasticizers include rul~u-baic 60, SMG, mono and d~ id~o and distilied ...o"o~iy.,c.id~,,,. Other speciaiized plasticizers having a boiiing point above the maximum i . e reached by the mixture duting the fotming process can âiS0 be used. These chemicais, which include pvl~ ,..e giycol (below 600 MW), giycetin, and sorbitoi, tend to take the place of water and function as plasticizers with moisture as low as 5~/o. They ate beiieved to attach themseives to the hydroxyl gtoups of starch molecules ~md form a hinge-iike structure. Since the plasticizers do not vaporize duting the forming process, they remain within the form-stable article, thereby softening the statch-bound mattix.
Finaiiy, ctoss-itnking admixtures such as !' ' ' ' .rd'~ hylulcas~ and meiamine ' ' ', d., resins can be added to the mixture to produce a less water soiuble statch-based bindet. The ctoss-iinking admixtures bind to the hydroxyl ions of the statch-based binder, which slow down the water ~ ~ab~ul~livl. rate of the statch-based binder. As a tesuit, the finai articles obtain form stability at a faster rate, have higher strength, and ate able to retain Gquids longer before faiiure (e.g., a cup can hold water longer before it starts - to leak).
The above-listed admixtures ate typically added in a range between about 0.5~/0 to about 15% by weight ofthe totai soiids in the mixture, or preferably about 1% to about 10%, and more prefetably from about 1% to about 5%.

, _ _ . .. , . .... .. , . ~ . . ....... ........ . . ... ...... .

wo s6/052s4 P~
~9~ oS9 52 V. PRQcEsslNG APPARATUS. CONDITIONS. AND RESULTS.
The articles of ~ ul~,Lul c of the present invention are produced through a multi-step process. The steps include preparing the mixture, forming the mixture into the desired articles, and ~ the resulting articles. Additional steps can selectively 5 include the printing, coating, and packaging of the final articles. The apparatus used in the processing steps are discussed below. The inventive articles can be prepared using cu.... ' equipment well known to those skiUed in the arts of polystyrene foam, paper, plastic, cement, and edible wafers. The equipment, however, must be uniquely combined and arranged to form a functional system that can ~I~.urAcLul~ the present articles.
10 Fu~ ...u. c, slight . o~ ;- ." ofthe equipment may be required to optimize production of the articles. The AI I AI I~,. ~1 - ~1, ~tlo~l;fi ~ and operation of the equipment needed to ..~.ur~tu, c the inventive articles can be performed by those skiUed in the art of using the Cul-~...-i;uUdl equipment in light ofthe present disclosure.

15A. PreParin~ the Mi~lture.
As depicted in Figure 4, the moldable mixture is preferably prepared in a rnixing tank 20 fed by bulk storage ceUs 22. The number of storage ceUs 22 is dependent on the number of r -- r ' to be ,uu,~t~,d into the mixture. Storage cells 22 typicaUy comprise dry load cells 24 and liquid load cells 26. Dry load ceUs 24 house solid 20. -- such as the starch-based binder, fillers, and fibers. Dry material metering units 28, typically consisting of some form of auguring system, ~ "~ and accurately measure and feed the desired amount of dry mixture into mixing tank 20.
Liquid load cells 26 house liquid r,~ , such as the solvent and different liquid rheology-modifying agents. When a~ , ~ , automatic stirrers can be positioned 25within the liquid load ceUs 26 to help prevent separation or settling of a liquid. Metering pumps 30 r ' '- "~ and accurately measure and feed the liquids into mixing tank 20.
Mhong tank 2û is preferably a high energy mixer capable of quickly blending the into a h...,.~ c moldable mixture. Such high energy mixers include the TMN turoo batter mixers that are available from Franz Haas W. r~ ' ' ~ of VieMa,30 Austria. Alternative high energy mixers are disclosed and claimed in U.S. Patent No.
4,225,247 entitled "Mixing and Agitating Device"; U.S. Patent No. 4,552,463 entitled "Method and Apparatus for Producing a Colloidal Mixture"; U.S. Patent No. 4,889,428 entitled "Rotary Mill"; U.S. Patent No. 4,944,595 entitled "Apparatus for Producing Cement Building Materials"; and U.S. Patent No. 5,061,319 entitled "Process for 35 Producing Cement Building Material". For purposes of disclosure, the foregoing patents are ~Juldied herein by specific reference.

_ _ . ....

21~7~ig P~
WO 96/U5254 . ._f Alternatively, a variable speed mixer can be used to provide low energy Dg.
Variable speed mixers include the Einch Rv~ Vhere fragile f llers or aggregates, such as glass spheres, are being ill-~Ul,UUI attJ into a mrxture, it is preferred to use low energy r~3ixing so as not to crush the aggregate. Low energy mixing is more important for high 5 viscosity mixtures. As the viscosity increases, the shear force applied to the mixture increases, thereby increasing the damage to the fragile aggregates.
As further depicted in Figure 4, once the mixture is prepared, it is pumped through an osciDating screen 32 to a storage mixer 34. Oscillating screen 32 helps to separate out and disperse unmixed clumps of the solids. Storage mixer 34 functions as a holding tank 10 to permit continuous feeding of the moldable mixture to the fornning apparatus. The moldable mixture is fed to the forming apparatus via a uu~ iu~ul pump 36.
In one ~ ~I o~ storage mixer 34 is sealed closed and a vacuum pump 38 is attached thereto. Vacuum pump ~8 applies a negative pressure to the mixture to remove air bubbles entrained in the mbcture. As previously discussed, air bubbles can cause 15 surface defects within the final products.
Storage mixer 34 '~, stirs or mixes the moldable mixture at low energy to prevent settling within the moldable mrxture. Where the forming apparatus operates on batch processing, as opposed to continuous processing, storage tank 34 can beeliminated and the mixture fed directly from mrxing tank 20 to the forming apparatus. A
20 complete automated system of load cells and mixers includes the DAN~X moldable batter mixing system that can be purchased from Franz Haas ~V,~' T~ U ;~ . n~ n M.B.H. of Vierma, Austria.
-Where a thicker or more viscous moldable mrxture is desired, it may be necessary to use an auguring system to mix and transfer the moldable mixture. In one t ~ ~ " t, 25 the materials ;.r~,u~ yu~ aLcd into the moldable mixture are '1~ and . '!~
metered, mixed, and deaired by a dual chamber auger extruder apparatus. Figure 5depicts a dual chamber auger extruder 40, which includes a feeder 42 that feeds the moldable mixture into a first interior chamber 44 of extruder 40. Within first interior chamber 44 is a first auger screw 46 which both rnixes and exerts forward pressure 30 advancing the moldable mixture through first interior chamber 44 toward an evacuation - chamber 48. Typically, a negative pressure or vacuum is applied to evacuation chamber 48 in order to remove unwanted air voids within the moldable mb~ture.
Thereafter, the moldable mixture is fed into a second interior chamber 50. A
second auger screw 52 advances the mixture toward the article forming apparatus. Auger 35 screws 46 and 52 can have different fight pitches and o~ ,. to assist inau ~ ,..,.,.-t of the mixture and performing low and high shear energy mixing.

- , : ~, .
_ _ _ _ . .. . . ... _ .. . ..

wo s6/052s4 ~,~9~ os9 Auger extruder 40 can be used to ;..,~.1,....l....ly mix the .,u.."., for the moldable n~ixture, or, as shown in Figure 5, can be fed by a mixer 54 A preferable twin auger extruder apparatus utilizes a pair of uniform rotational augers wherein the augers rotate in the same direction. Counter-rotational twin auger extruders. wherein the augers 5 rotate in the opposite directions. accomplish the same purposes. A pugmjl may also be utilized for the same purposes. Equipment meeting these ~ are available from Buhler-Miag, Inc.~ Iocaled in ~ , Minnesota.
High viscosity, moldable mixtures are typically fed into the forming apparatus by either a two-stage injector or a ~ c-,;~- u~,ali,.~ screw injector. As depicted m Figure 6, a lû two-stage injector 56 has separate co.,.l, .L...,...~ for mixing or advancing and injecting.
The mixture is conveyed to an extruder screw 58, which feeds the mixture to a shooting pot 60. Once shooting pot 60 is filled. an injection piston 62 pushes a defined quantity of the mixture into a flow channel 64 that feeds the forming apparatus.
As depicted in Figure 7, a . t~ .. û~,~Lhlg screw injector 66 comprises a chamber 15 68 having a screw auger 70 '~ ~' " ".y positioned therein. The moldable mixture is fed into chamber 68 and advanced by screw auger 70. As screw auger 70 rotates, it retracts and feeds the mixture to injection end 72 of screw auger 70. When the required volume of the mixture has ~ ' ' at end 72, screw auger 70 stops rotating and moves forward to inject the mixture into flow channel 64 and ~ to the forming 20 apparatus.

B. Formin~ the Mi~ture into the Desired Article.
Once the mixture is prepared, it is preferably formed into the desired shape of the article through the use of heated molds. Figure 8 depicts a heated male mold 74 having 25 a desired shape and a heated female mold 76 having a , ' y shape. Female mold 76 comprises a mold body 78 having a flat mold face 80 with a receiving chamber 82 bored therein. Receiving chamber 82 has a mouth 84 through which it is accessed.
Male mold 74 comprises an attachment plate 86, a die head 88 having a shape ~ly 1., .. ~,pl. -- a ~y to the shape of receiving chamber 82, and a venting ring 90 extending between attachment plate 86 and die head 88. Venting ring 9û is slightly larger than mouth 84 of receiving chamber 82 and contains a plurality of venting grooves 92 that are lnngit~ , aligned wjth die head 88.
In the preferred ~ , the molds are vertically aligned wjth female mold 76 being positioned below male mold 74. In this orientation, as shown in Figure 9, receiving chamber 82 acts as a container for receiving the moldable mixture from a filling spout 94.
Once the mixture is positioned within female mold 76, the molds are mated, as shown in w~ s6la5254 219 7 ~ ~ 9 r~

Fgure 10, by inserting die head 88 into receiving chamber 82 untii ven~ ring 90 comes to - rest on mold face 80 around mouth 84. Die head 88 is sGghtly smaiier than receiving chamber 82 so that when the molds are mated. a mold area 96 exists between maie mold 74 and femaie mold 76. As previously discussed, the amount of moldable mixturs positioned in female mold 16 preferabiy oniy fills a portion of mold area 96.
In the mated position as shown in Figures 11 and 11A, vent grooves 92 with mold area 96 to form vent holes 98. r.~ , a venting gap 100 is formed between mold face 80 and atjtachment plate 86 as a result of venting ring 90 resting on mold face 80. During operation, the heated molds cause the moldable mixture to expand and dry into a solid article according to the process and parameters as previously discussed. F,xcess materiai 102 and vapor is expelled from mold area 96 through vent holes 98 and into venting gap 100. Once the mixture becomes form-stable in the desired shape of the article, maie mold 74 and femaie mold 76 are separated. As depicted in Figure 12, a scraper blade 103 can then be pressed aiong the length of mold face 80 to remove excess materiai 102.
The molds can ihave a variety of shapes and sizes to form the desired article.
However, there are two general types of molds: duai molds and spGt molds. As shown in Fgure 13, duai mold 104 comprises a singie maie mold 74 and a single female mold 76.
This type of mold is used for maicing shailow articles, such as plates and Gds, that are easiiy removed from the molds. SpGt molds 106, as shown in Figure 14, comprise a singie maie mold 74 and a female mold 76 that can be separated into mold haives 108. Mold haives 108 are separated after the article is formed to permit easy removai of the article.
Split molds 106 are used for the production of deep recessed articles such as cups and bowls that can be difficult to remove from a mold.
One method for removing articles from the mold is by a suction nozzie 110. As shown in Figure 14, suction nozzie 110 has a head 112 with vacuum ports 114 located thereon. Head 112 is designed to ~ A ;ly fit within the hardened article.
Accordingiy, by inserting head 112 into the article and applying a slight negative pressure through vacuum ports 114, the article can be picked up and moved to a conveyor belt for subsequent processing.
- The molds are preferably made of metals such as steel, brass, and aiuminum.
PoGshed metais, including chrome and nickel, along with Teflon coatings, make it easier ~ to remove the articles from the molds and create a smoother finish. The materiai of the molds must be able to withstand the It.l.~ and pressures, as previously discussed, 1~ _ t d during the ~ 'AI ml ;' ~g process.

,:~ . ._,,, ~, ,, ,,:,, ,: ,,, r,; _,,,,, _, _, ,,,,, ,_, _,,,, ,_,,,,,, _,, ,,, __,,__, ,___ _ _ _ , , wo9610s2s4 - ' , r~1,. .( 2~9~0s9 The molds can be heated in a vanety of ways. For example. extemal heating elements, such as gas burners, infrared light, and electncal heating elements, can be attached or directed at the molds. Altematively. heated liquids, such as oils, or heated gases, such as steam, can be piped through the molds to heat them. Various types of heating can also be used to vary the tc~ .,.aLul= of the molds along the length of the molds in order to vary the properties of the hardened matrix within the molded article. .
It is also possible to heat the mixtures without heating the molds. For example. the molds can be made out of ceramic and 111;~,1 u . . _~s be applied to heat the mixture.By varying the temperature and processing time it is possible to affect the density, porosity, and thickness of the surface layer. or skin. Generally, in order to yield a molded article having a thiMer but more dense surface layer, the molding t~ atul~ is lower, the molds have fewer vents, and the moldable mixture has a higher viscosity. Theviscosity ofthe mixture can be increased by adding a rheology "C~,U.g agent, such as Tylosel9, including less water, or by using an aggregate material having a higher specific surface area.
One method for mass producing the articles of the present invention is by meâns of the baking machine depicted in Figure 15. As depicted in Figure 15, baking machine 116 has a forming station 118 attached to and, ' _ with a baking oven 120.
Baking oven 120 includes an insulation wall 172 that defines an oven chamber 124.
Heating elements 126 are positioned within oven chamber 124 for heating oven chamber 124. A track system 128 extends through both fom~ing station 118 and oven chamber 124 in a continuous, circular fashion. Track system 128 includes an upper track 130 and a lower track 132. Riding on tracks via wheels 134 are a plurality of ' l, hingedly attached baking molds 136. As best shown in Figure 16, each mold has a top plate 138 and a bottom plate 140 with the plates being connected touether at one end by a hinge 142. Top plate 138 and bottom plate 140 include a male mold 74 and a female mold 76, respectively, as previously described.
Baking machine 116 functions as a continuous process to mass produce desired articles. Production of the articles is perfommed in several stages that are ' 1~, being performed by different baking molds 136 in the chain of molds. As shown inFigure 16, in the first stage, baking molds 136 are open and positioned under a filling spout 144 for receiving the moldable mixture. Baking molds 136 are opened by separating the upper and lower tracks 130 and 132 on which the top and bottom plates 138 and 140 ride. respectively. Filling spout 144 is used to discharge a selected quantity ofthe moldable mixture into female mold 76.

~o 9C/05254 Once femaie mold 76 is fiiied. baking molds 136 advance and are closed as a result - of upper and lower trjacks 130 and 132 closing together. To facilitate cyciic separation ofthe molds, as previously discussed, the tracks can be designed to cyclicly diverge and converge as shown at point C on Figure 15. thereby repeatedly openins and closing the 5 molds. Once cyciic separation is completed. the molds are locked and the forming process is continued One preferred mechanism for locking the molds is described in United States Patent 4.953,453, issued September 4. 1990, to Franz Haas. Sr. and entitled "Apparatus for Operating Locks of Babng Tongs for Producing Rotatable, Preferably Edible Wafas 10 from Wafer Dough in a Wafer Baking Oven or an Automatic Wafer Baicing Machine"
(hereinafter the "Haas '453 patent"). For purposes of disclosure, the above patent is ;u.,ullJul~Led herein by specific reference. The Haas '453 patent discloses a locking that prevents the forcing of the lock or disruption of the process when the molds fail to properly aiign and close. More ..u..~. ' locking ' can be used; however, they must be able to withstand the pressures produced by the heated mrxtures.
Baking mold 136 travels the length of baking oven 120, rotates to an inverted position, and then travels back to forming station 118. In accordance with tbe present invention, heating elements 126 are positioned within oven chamber 124 for heating baking molds 1~6 as they travel through oven charnber 124. By way of example and not by iimitation, heating element 126 can include electricai heating eiements, gas burnas, and infrared lights.
The speed at which the molds travei through baking oven 120 is in part iimited by tbe re~iuired time it takes to stop and f 11 baking molds 136. The fiiiing time is, of course, dependent on the size of the article being molded. The time that the mixture remains in the oven is dependent on several variables, including the solvent content, oven t"..~ Lul c, and fiiing volume, as previously discussed. To pemlit the adjustment of the forming time without modifying the speed of the molds, baking oven 120 is buiit to include unit sections 146. Unit sections 146 can be removed from baking oven 120 or new sections can be added to bakmg oven 120 so as to permit selective adjustment of the - 1ength of baking oven 120. The fomling time and t.,.llpL.~Lul c are selected so that when baking molds 136 retum to fomling station 118, the article can be removed from the molds in a fomm-stable condition.
Referring again to Figure 15, once the molds retum to foming station 118, bakingmolds 136 are again opened by separating upper and lower tracks 130 and 132. A
scrapper blade 148, depicted in Figure 1~, can then be passed over femaie mold 76 to wo 96/0S254 2 1 9 7 0 S 9 . .

remove excess material 102 that may have exited through vent holes 98 during the heating process. The article can then be removed from female mold 76.
The articles can be removed from the molds in a variety of different marmers. For example, as shown in Figure 16~ when dual molds 184 are used. as the separated molds 5 pass through forming station 118, the molds are again rotated so as to invert back into their original onentation. As the molds are rotated, the force of gravity causes the article to fali out of baking molds 136. A conveyer belt can then be used to catch and transfer the article for subsequent processing. When split molds 106 are used, the removai procoss entaiis separating of mold halves 108 and ailowing the articles to fali down a coiiection chute 149 under the force of gravity, as shown in Figure 15. The articles then continue aiong a conveyor beit through the remaining processing steps. With the articies rernoved form the molds, the molds return to filling spout 144 and the process is repeated A typical baking machine 116 may be selected from a variety of, , ~
available baking machines, such as the SWAK T, SWAK I, and SWAK wafer bal~ng 15 machines, and the STAK, STAZ and STA ice cream cone machines. These baking machines can be purchased from Franz Hazs W:~' ' T-' ~
M.B.H. of Vienna, Austria. Aithough the above-listed machines have been used in the past primarily for the production of edible wafers and ice crearn cones, the listed machines crn be used in the present invention by inser~ng the proper mold shapes, which have been 20 selectively modified as previously discussed, depending on the desired processing parameters and the qpe of article to be produced.
As an alternative to the Haas baking equipment. Cu~ liivllli expanded poiystyrene ,....,.,r~. l,.,;"g equipment (hereinafter "EPS machine") can be modrfied to produce the articles of the present invention. As depicted in Figure 18, a c~
EPS machine comprises a maie mold 150 and a femaie mold 152, the molds being verticaiiy aligned with female mold 152 being on top. Femaie mold 152 includes a mold body 154 having a receiving chamber 156 defined by a mold wall 158. At one end of mold waii 158 is a mounting iip 160. Located within mold wali 158 is a female waii caviq 162. C~ o with receiving chamber l56 is a fiiiing channel 164 that is selectively openeri and closed by a piston 166. Finaily, - -~ . with filling channel 164 is a fiiling tube 168 that is aiso opened and closed by piston 166.
Maie mold 150 has a die head 170 having a shape ' "~, .. ,.,.1 l .. ~'Y
to receiving chamber 156. Die head 170 has a base 172, a side waii 174, and a top 176.
Cheul.~el~l.iioll~lly located within die head 170 near top 176 is a chamber 178.Positioned within chamber 178 is an expandable vent spring 179. Chamber 178 C~J''~ with a pressure tube 180 positioned within die head 170. Chamber 178 r~ s~.
wo 96/n5254 ~

aiso .~ with the Clliil UlUl~.,.lL through a venting slot 181 that extends between - chamber 178 and the exterior of maie mold 150. Located at base 172 is a venting groove 182 that is ~ i L ~ r aiigned with mounting lip 160. Finaily, a male wall cavity 184 is positioned within die head 170 near side wall 174 and top 176.
Durjng typicai operation of the EPS machine, the molds are initially matedl as shown in Figure 19, to form a mold area 186 between the molds. Air is blown through fiiiing charmei 164 into mold area 168 and exits through a vent gap 188 located between mounting lip 160 and venting groove 182. The blowing air causes a suction that puiis pol~ y~ e beads located in filling tube 168 into mold area 186. Venting gap 188 is sufficientiy small to prevent the p.Ji~i.Ly~ beads from escaping.
Once the mold area is filled with the pol~ .e..., beads, fiiiing channel 164 is closed by piston 166. Stearn is passed into femaie wa!l cavity 162 and maie wali cavity 184 heating femaie mold 152 and maie mold 150. Steam is aiso blown into mold area 186 through pressure tube 180 and venting slot 181. As the steam enters chamber 178 through pressure tube 180, the pressure resulting from the steam causes vent spring 179 to expand, permitting the steam to pass through venting groove 182. Once the steam is gopped, venting spring 198 retracts, preventing material from mold area 186 to enter into chamber 178.
As a result of the heated geam, the poi~ n~, beads heat, expand, and melt 20 together, forming the desired article. Cold water is then passed through femaie waii cavity 162 and maie waii cavity 184 to cool the molds and c ~ q : ly harden the pcl~Lyl~
article. Once the article is formed, the molds are separated and the article removed. The article is most easily removed by blowing air through chamber 178, which pushes the article offmaie mold 150.
A .,u.. ~. ' EPS machine can be used in a couple of different methods to produce the articles ofthe present mvention. In the ftrst method, the EPS machine is used in ' '~, its normai ~ ~ - r~K, - OI ;r~ By using a mixture having a .,onJ.st~ ,y simiiar to that of a wet powder, the mixture can be sucked into mold area 186 by passing air through fiiiing channel 164. However, since the mixture of the present invention hardens upon being heated, as opposed to cooled, the waii cavities 162 and 186 should becontinuaiiy heated by geam or other heated iiquids, iike oil. It is aiso preferred to insulate and cool filling tube 168. Heating of fiiiing tube 168 can result in the gelation and hardening of the starch-based binder, thereby clogging tube 168. N~ ,th~ ." by providing a cool-down cycle after the heating cycle, it is possible to demold the articles whiie maintaining enough moisture within the structurai matrix to keep it f exible without the need for a subsequent ~ ... ,.1;l ;~ ., .;, .g step.

. ,, . . , . , , . . ., . . _ . . .. ..... _ . . . . .

wo 96/05254 ~1/~.~, .1 S~ ~

By regulating the size of vent gap 188. pressure can be built up within mold area 186, thereby producing the foamed articles in the same maMer as previously discussed.
One advantage of using the EPS machine in its normal ~;v~ ulatiull is that the final articles remain on male mold 150 after the molds are separated. The article can then be S easily removed by blowing air through pressure tube 180.
In an alternative method, the molds of the EPS machine can be inverted so that female mold 152 is vertically aligned below ma!e mold 150 and acts as a receptacle for the moldable mixture. The mixture can then be poured into female mold 152 through anexternal spout while the molds are open. The molds can then be closed and the article 10 formed in the same maMer as previously discussed.

C. C ' ~ _ the Articles.
If the resulting form-stable articles have insufticient fiexibility for their intended use, they are transferred to a high humidity chamber. As previously discussed, the 15 humidity chamber provides an L~;-vlhl~ lL of controlled t~ .,.dlul~ and hurnidity to permit rapid moisture absorption by the form-stable articles. Increasing the moisture content in the articles improves certain properties, such as the elasticity, ~I; .,~1~- ~ - ' before-failure, and fiexibility.
The humidity chamber can be designed for either batch processing or continuous 20 processing. In continuous processing, the humidity chamber comprises either a tumnel or tower through which the articles pass without stopping. The length or height of the chamber, speed of the conveyor system, humidity within the chamber, and h,~ Lu within the chamber are optimized to produce an article having the desired moisture content in a minimum time period and minimum cost. Preferred variables for moisture 25 content, humidity level, and t~,...p~ tul e are previously discussed.
The moisrure can be produced through ~,u.,._,t;v..d hot and cold steam processesas well as ~ JII with ultrasound. Examples of commercially available humidity chambers that can be used in the present invention include the KTV, KT, and KTU wafer sheet ~, -",1;1;", - tuMels and towers available from Franz Haas W ~ of 30 VieMa, Austria.

D. Coatin~s and Coatin~ Anr)aratus.
It is within the scope of the present invention to apply coatings or coating materials to the articles. Coatings can be used to alter the surface, I - - - r I rl ;~ of the 35 articles in a number of ways, including sealing and protecting the article. Coatings may provide proteaion against moisture, base, acid, grease, and organic solvents. They may ~ ~ _ . _ .. ....

W0 96/05254 ~ ~ 9 ~ o 5 9 aiso fiii in voids on the surface of the article and provide a smoother, giossier, or scuff-resistant surface. ru. ~L. u~W ~ coatings can help prevent aggregate and fiber "fly a vay" .
Coatings may also provide reflective, electrically conductive or insulative properties.
They may even reinforce the article, particuiarly at a bend, fold, edge or comer Some of 5 the coatings can aiso be utiiized as laminating materials or as adhesives.
Appiication of a coating may also be used to regulate the moisture content of the present articles. It is theorized that the moisture coment of an article wiii eventuaiiy reach a point of equilibrium with its Gl~vhulu~ L. That is, reiatively dry articles wiii adsorb moisture in a humid climate and ~ ~ ' ' articles will ioose moisture in a dry ciimate.
10 The appiication of a coating after ~ ; .g the article to the proper moisture conterlt can prevent the exchange of moisture between article and the ~u..~ " v e~
'rhe object of the coating process is usuaiiy to achieve a unifomm fiim with rninimai defects on the surface of the article. Selection of a particular coating process depends on a rlumber of substrate (ie., article) variables, as weii as coating L. ~ variables. The 15 substrate variables include the strength, wettability, porosity, density, ~ .u~ , and uniformity of the article. The coating ~ variables include totai soiids content, solvent base, surface tension, anù rheology.
The coating can be applied either during the fomling process or after the article is formed. The coating can be fommed during the fomling process by adding a coating 20 materiai that has ~y~ the same melting L~ Lu.~ as the peak L~ Lur~; of the mixture. As the mixture is heated, the coating materiai melts and moves with the vaporized solvent to the surface of the article where it coats the surface. Such coating materiais include selected waxes and cross-iinicing agents.
The coatings may be applied to the article after fommation by using any coating 25 means icnown in the art of r ~ g paper, paperboard plastic, polJ~iy.."le, sheet metal, or other pacicaging materiais7 including blade, puddle, air-icnife, printing, Dahigren, gravure, and powder coating. Coatings may aiso be appiied by spraying the article with any ofthe coating materiais iisted below or by dipping the article into a vat containing an appropriate coating materiai. The apparatus used for coating will depend on the shape of 30 the article. For example, cups will usually be coated differently than flat plates.
As the articles having a starch-based binder have a high affinity for water, thepreferred coatings are non-aqueous and have a low poiarity. Appropriate coatings include paraffin (synthetic wax), shellac; xylene-ru. '' ' yJ~, resins condensed with 4,4'-i~UIJlU~ .,. r~:pl,....~ uhrdlill epoxy resins; drying ûiis; ~ d otis from 35 Llil51yuclidcr~ or fatty acids from the drying oiis to fomm esters with various giycols ~butylene giycol, ethylene glycol), sorbitol, and trimethylol ethane or propane; synthetic .. .. . .. . . .. .

WO 96105254 , ; 7, =
5~ ~

6 ~
dry~ng oiis including polyl~uLad.~..c resin: naturai fossil resins including copal l tropicai tree resins, fossil and modern), damar. elemi. ~ ilsonite (a black. shiny asphaitite, soluble in turpentine), glycol ester of damar, copal, elemi. and sandarac (a brittle, faintly aromatic rranslucent resin derived from the sandarac pine of Africa), shellac, Utah coai resin; rosins 5 and rosin derivatives including rosin (gum rosin, tall oii rosin, and wood rosin), rosin esters formed by reaction with speciiic giycols or aicohols, rosin esters formed by reaction ~ ~ h!~lw, and rosin saits (caiciurn resinate and zinc resinate); phenolic resins formed by reaction of phenols with ru.,.,aldci.yde; polyester resins; epoxy resins, cataiysts, and adjuncts; . u~e~ n~ resin; petroleum h~dluLr~iJull resin (uy Iu~ - type);
10 . terpene resins; urea-ru~ de resins and their curing cataiyst; triazine-r ' ' '1~ d~
resins and their curing cataiyst; modif ers (for oils and alkyds. including polyesters); vinyl resinous substances (poiyvinyl chioride, polyvinyl acetate, polyvinyl aicohol, etc);
ceiiuiosic materiais (CaliJuA~ , ceiiulose acetate, ~,h~ hJLUA.~ .J'~ " ' etc.); styrene polymers; po'~,.hJk.l.., and its uul~ol~n.~ , acrylics and their cût~ol~ , 15 methyl ' ~:at." ethyi u~.,,h~ yl~L~, waxes (paraffin type I, paraffin type 11, ~UI.~LhJ~ , sperm oii, bees, and spermaceti); melamine; pol~ , polylactic acid;
BiopolJ (a PUIJh~LUAYlJULYI ~ LUA.~ UyUI~/..._.), soybean protein; other synthetic polymers including l,;udc~ L,i,le polymers; and elastomers and mixtures thereo~ Biopoll ;5 r ~;i by ICI in the United Kingdom. Appropriate inorganic 2û coatings include sodium siiicate, caicium carbonate, aiuminum oxide, siiicon oxide, kaolin, ciay, ceramic and mixtures thereo~ The inorganic coatings may aiso be mixed with one or more of the organic coatings set forth above.
In some cases, it may be preferable for the coating to be elastomeric or deform-able. Some coatings may aiso be used to strengthen places where the articles are severeiy 25 bent. In such cases, a pliable, possibly el~ctoml rir, coating may be preferred. A
waterproof coating is desirable for articles intended to be in contact with water. If the articles are intended to come into contact with foodstuffs. the CoatLng materiai wili preferably comprise an FDA-approved coating.
Polymeric coatings such as ~,ul~.,L}.JL,..~ are useful in forrning generally thin layers 30 having low density. Low density pOIy~LhJ k,..~, is especially useful in creating containers which are iiquid-tight and even pressure-tight to a certain extent. Polymeric coatings can aiso be utilized as an adhesive when heat seaied.
Aiuminum oxide and silicon oxide are useful coatings, particularly as a barrier to oxygen and moisture. The coatings can be applied to the article by any means known in 35 the art, including the use of a high energy electron beam e ~ ~yOl~iLiull process, chemicai plasma deposition and sputtering. Another method of forming an aluminum oxide or _ W0 96/0525~ 21~ 7 ~

silicon oxide coating involves the treating of the article with an aqueous solution having an appropriate pH level to cause the formation of aluminum oxide or silicon oxide on the article due to the f ~ ; ;f~; of the article.
Waxes and wax blends, particulafly petroleum and synthetic waxes, provide a 5 barrier to moisture. oxygen, and some organic liquids. such as grease or oiis. They also aiiow an article such as a container to be heat sealed. Petroleum waxes are a particularly useful group of waxes in food and beverage packaging and include paraftin waxes and ~Ifl~,lu~,~y~Lllline waxes.

E. ~e~:-It r~ay be desurable to apply print or other indicia, such as i ' ', product i " container ~ : r, - ;~ ., or logos, on the surface of the article. This can be L c.,~ 1 using any LUII~.,..dUUld printing means or processes known in the art of printing paper or cardboard products, including j ' ~, . ' relief, intaglio, porous, and 15 impactless printing. Conventional printers include offset, Van l~am, laser, direct transfer contact, and Ih ~ printers. However, essentiaiiy any manual or mechanical means can be used.
The type of printing and printer used depends in part on the shape of the article.
For example, fiat plates wiii require a different printing apparatus than a cup. In addition, 20 the molds can be specially designed to provide embossing on the surface of the article.
The anicle can also be provided with a watermark. Because the articles have a relatively high porosiy, the appiied ink wili tend to dry rapidly. One skiiled in the art will appreciate that the article porosiy and ink quantities must be compatible. In addition, decais, iabels or other indicia can be attached or adhered to the article using methods known in the art.
F.
A custom automatic stacker can be instailed at the end of . . r~ O line to create stacks of articles. The stacks are loaded into poly bags and then seaied. Finaiiy, standard carton I " .,'1 " ", equipment is used to package the articles and prepare 30 them for shipping. The packaging equipment includes ~,UII~..ILiUlldi equipment used in - packaging articles made from paper, plastic, pûl.~.~LylGIle foam, or metai.

G. Phvsical Pronerties of the Articles.
In view of the foregoing, it is possible, by using a l~u~u~L~u~lu~l engineering 35 approach, to obtain a wide variety of articies of varying shapes, strengths, flexibiiities, stifiness, insulation, and other physicai properties. In generai, the f exurai strength of the wO 96/05254 2 19 7 ~ ~ 9 1 ~". ' .

articles will preferably be in a range of about 0.5 I~Pa to about 8 MPa, more preferably in a range from about 0 7~ MPa to about 6 MPa, and most preferably in a range from about I MPa to about 4 IvlPa. The range of strain of the articles (Le., the amount of stram before rupture), which wiil preferably be in a range from about 1% to about 15%, more preferably from about 1% to about 10%. and most preferably from about 1% to about 5%. The specific strength of the articles will vary in a range from about 2 MPa cm3/g to about 80 ~a cm3/g. The fracture energy ofthe articles wiil preferably be in a range from about 5 J/m2to about 3000 J/m2, more preferably from about 1~ J/m- to about 1500 J/m2, and most preferably from about 25 J/m2 to about 600 J/m2.
io Vl. E~AMPLES OF T~E PiREFEiRRED EMBODIMENTS.
Outiined below are a number of examples showing the ~..~.ur~tu,~ of articies from the ulOI~ filled, starch-bound, moldable mixtures of the present invention.The examples compare the properties of the articles for varying ~ and processing conditions.

F.~ ~rnr~ 1-13 Drinking wps were formed from moldable mixtures containing different types of inorganic aggregates to determine the effects of the different aggregates. Each of the moldable mixtures had the foiiowing basic mix design measured by weight:

39 8% Stalok 400 (modif ed potato starch) 9 9~% inorganic aggregate 49.7~% water 0.5% magnesium stearate Each moldable mixture was prepared in a small Hobart mixer. Flrst, the dry ingredients (including the inorganic aggregate, starch, and magnesium stearate) were completely mixed. Then the water was added slowly while the dry materials were being 3 0 mixed untii a 1~ u~ ~ mixture was obtained. The mixtures were extracted from the Hobart mixing bowl using a syringe. The weight of the moldable materiai used to u~llural,lul~ a cup for each mixture was determined by first weighing the syringe containing the moldable mixture, expelling the contents of the syringe into the moldmg apparatus, and then weighing the syringe.
The molding system included a male mold made out of tooled brass and a femaie mold made out of tooled steel, Ihe molds being configured ' "y according to Wo 96105254 2 1 9 7 ~ 5 9 hgure 8. The rnoids were designed to produce i2 oz drinking cups having a smooth- surface and a thickness of about 4 mm. The maie moid contained four vent grooves that formed four vent holes.
The cups of Examples I - 13 were obtained by heating each selected moldable 5 mixture between the molds at a Itl~ ILUI ~: of about 200~C. Once the articles became significantly form-stable, they were removed from the molds amd placed in an oven for about 1.5 hours at a . ~Lul~ of 105~C to remove the remaining moisture. The moisture was removed so that subsequent testing of the cups would better reflect the effects of the component as opposed to the effects of the starch-based binder moisture 10 content. It was assumed that the weight loss of the cup during drying im the oven was a loss of water. The measured weight loss was thus used to determine the moisture of cups upon being removed from the mold. The cups were then seaied in plastic bags to mainlain a constant humidity until the cups could be tested.
Sl~m~ 7~ beiow is a list of the selected ir!organic aggregates and the resuiting15 properties of the cups formed from each of the mix designs:

CupMoish~e Out of Thc~md Therm?l ExunpleAggregllte Dwcc)y Mold Contuct.(~-h-oFI

l. Gama Sperse 0.190 3.0 0.046 3.15 2. Carbitai 50 0.185 2.5 0.044 3.25 3. R040 0.215 2.7 0.045 3.20 4. Mica4k 0.205 2.6 0.048 3.10 5. Glass 0.190 4.9 0.047 3.15 Bubbles 6. Polvmica400 0.195 2.0 0.049 2.90 7. Aerosil R972 0.125 4.2 0.040 3.68 8. Aerosil 130 0.135 4.0 0.054 2.70 9. Aerosil200 0.145 4.1 0.046 3.15 10. Aerosil 380 0.155 4.3 0.048 3.10 11. CabosilEH5 0.140 2.8 0.041 3.60 12. Wollastonite 0.195 2.1 N/A N/A

13. Sil-co-sil 0.200 ". I N/A N/A
Siiica Sand WO 96/05254 ~ _ 2~ o59 66 Exrmple Inorgttnic Energy to Dis,olace-ment to Perl~Strf~ners .~gregate Failttre (mn Failttre ~o/o) Load(Nlm) I Gama Sperse 6.0 3.1 5.00 2.5 2. Carbital 50 9.0 3.5 5.10 2.7 3. R040 7.0 3.1 5.05 Z.6 4. Mica 4k NIA N/A N/A N/A
5. Glass Bubbles 9.5 3.2 5.20 3.4 6. Polymica400 10.0 2.7 5.15 2.4 7. Aerosil R972 7.0 4.0 4.95 1.9 8. Aerosil 130 7.0 3.5 4.90 1.8 10 9. Aerosil 200 9.0 3.5 5.00 2.1 10. Aerosil 380 6.0 3.1 4.95 2.2 I l . Cabosil EH5 7.0 3.4 4.95 2.0 12. Wollastonite 8.5 3.1 5.10 2.9 13. Sil-co-sil 8.0 2.8 5.05 3.0 Silica Sand The properties analyzed include thermal properties and mechanical properties.
The thermal properties include thermal ~u 1~ e and thermal resistivity which were deterrnined by a transient hot-wire method. Three III~ >UI ~illl.,.~t~i were recorded for the thermal l,uuJu~livi~ of the side walls of the cups and the average value was reported.
20 Mechanical properties were defned by developing a test that would simulate the pinching between the thumb and the other four ftngers that a cup might experience during use. The results served as a means to compare cups produced from different r.~ "l.o~ attdunder different conditions. The strength and ductility were not easily ~ r due to the complex geometry. Instead the data is reported without ~ ;U n to the cross-25 sectional area.
The cups were positioned on an inclined platform. The inclination was adjustedso that the side edge of the cup was normal to the loading direction. The area below the top rim ofthe cup was chosen as the point of load application. This resulted in the most lc~ludu1;blc results. Loads were applied to the cups at the rate of 15 mm/min. until a 30 clear failure was observed. The 1l~ r :~ and the UUII~ UIlJ;ll~; loads were recorded.

WO96105~54 ~ B5~
.

The test provided a quaiitalive evaiuation of the mechanical properties Using the - defined testing method. a LU/~ S~ was made on the basis of peak load~ maximum d~ before failure, energy absorbed during fracture, and stiffness. The ensrgy of failure is the area under the load A; ~ curve measured from the origin to the S point offrst fracture. Each ofthe above properties are based on a statisticai average of seven identicai tests.
The tests showed that the fumed silica aggregates (Aerosii R972, 130, 200, 380 and Cabosil EHS) resulted in a density of about 30% lower compared to those where a different inorganic aggregate was added. The other inorganic aggregates had a iirrited 10 effectonthedensityofthecups,withtheexceptionofPolymicawhichaisodecreasedthe density by about 30D/D relative to cups using the other inorganic aggregates.
The dry peaic load and stiffness of the cups containing fumed siiica were affected to the same extent as the densiry; ~,p,~"u...~i-l.~ 30% of each was lost compared to cups produced without fumed siiica. The dry d;~ A~: to-faiiure and energy-to-faiiure 15 ~ t~ exhibited little or no change due to the addition of inorganic materiais.
The addition of Mica 4ic, giass bubbles, Woiiastonite, Poiymica 400, and siiica sand did not affect the energy-to-failure A~ -to-faiiure~ peaic load, and stift'ness to any significsnt degree. The one exception was Mica 4k which had a 30% increase in peak load. The vaiue for thermai properties were found to be in a band width of about 20 +10~/0 of the vaiue for cups produced with no starch-based binder substitute. The vaiues were ;".b 1.. 1 .~ of the type of inorganic aggregate used.
Based on the above tests, fumed silica aggregates appear to be less preferred since ~ they adversely affect the mechanicai properties of the articles. In contrast, the other inorganic aggregates can be used to replace at least 20% by weight of the starch-based 25 binder without ~ I.ifh,. .;ly affecting the mechanical properties of the articles. It is believed that fumed silicas produce a detrimental effect as a result of their low strength in .. ~ ;, ". to the other inorganic aggregates.

~Y'~nlnlf'C 14-~7 Cups were made using different ~ - ~A- _ ~ ~ A~ "' of caicium carbonate to determine - the effect of replacing the relatively expensive starch-based binder with less expensive caicium carbonate filler. The same procedures and apparatus as discussed in Examples 3 were used to make and test the cups of Examples 14-27. Each of the moldable mixtures included the following basic mix design measured by weight:

:_ _ __ _-- , . .,:, ., . : . _, ._ ,. ,:, . ._, . .,,, , ,,, _ _, . .

W096~S254 ~ 5 ~ P~

49 75% ~ 1;"" Stalok 400 potaro starch and inorganic aggregate 49.75% water 0.5% magnesium stearate Tests were run for two different types of calcium carbonate (Gama Sperse and RO40) at 20,40,50, and 60 weight percent inorganic aggregate based on the total weigh~
ofthe, ' of the starch-based binder and the inorganic aggregate. The same tests were also run on a mixture of Gama Sperse to which ''% by weight of puly~ ' ' has been added.
S ~ below are the selected ~ and the properties of tbe resulting 12 oz. cups.
Exrmple LrlorgDnic Derlsiy ~herm~l Displllce- PeakStiiiies5 Aggreg~te (ghc) Corlducl. Energy tom3a to b~
weight ~/3) (Wlm K) FniL (mJ) l:tDIure Gama Sperse 14. 0 0.19 0.044 7.0 2.9 3.2 6.0 15. 20 0.21 0.046 6.0 2.9 2.5 5,0 16 40 0,24 0 052 6.0 2.5 - -17~ 50 0.27 0.054 6.0 2.2 4.5 6.5 18. 60 0.28 0.053 6.0 2. 1 4.6 6.0 Gama Sperse w/ 2% pU~ y' ' ' ~

19. 0 0.16 - 4.5 2.5 2.4 4.0 20. 20 0.19 0.043 8.0 3.4 2.7 6.0 21. 40 0.21 0.045 7.0 2.6 3.2 5,5 22. 50 0.24 0.050 7.5 2.9 3,0 5.4 23. 0 0.19 0.044 7 0 2.9 3.2 O.0 24. 20 0.21 0.044 6.5 2.9 2.5 5.5 25. 40 0.25 0.044 4.0 2.5 2.8 4.5 26. 50 0.30 0.050 4.0 2.2 3,5 27. 60 0.38 0.058 4,5 2.1 4.5 6,0 . .

WO 96/0~254 2 ~ 9 7 ~ ~;g' '~ r~

~ 69 The tests showed that the density of the articles increases .",p., ' '~ 0.8% foreach weight percent of added Gama Sperse or R040 caicium carbonates, This l~'a ' ' '.
held true for the full range of Gama Sperse (0-60% by weight) and for R040 in a range from 0-40% by weight, Adding higher than 40% R040 by weight roughly doubled the 5 rate of increase ofthe density. The effect was siniiar for the samples that contained Gama Sperse with 2% pC ~...,lyl~ll.ll;ic by weight.
The thermal, ' ' ~;L~ results were somewhat unclear; however, there was an increase in Cu,.Ju~L;v;L~ as the fraction of the inorganic ag~regate was increased. The increase was in the order of about 0.2% per weight percent of calcium carbonate added.
The addition of calcium carbonate had little effect on the energy-to-failure, '', ' to-faiiure, or the peaic ioad. Aithough the dry stiffness was s ' ' "~
constant initiaily, it exhibited an increase of about 50% at the highest weight fractions of 50 and 60%. Based on the above tests, there was oniy a limited detrimentai effect on the behavior by 5~ m;.~,; up to 60% of starch-based binder with caicium carbonate.

~Y ~ IP~ 2~- ~9 Cups were made using different types of caicium carbonate to determine their effect on the fnai article. The same procedures and apparatus set forth in Examples 1-13 were used to make and test the cups of the present examples. Each of the moldable mixtures included the following co . ~ by weight:

39.8% Staiok 400 (modified potato starch) 9.Q5~.~o caicium carbonate 49.5~/0 water 0.5% magnesium stearate.

Summarized below is a iist of the selected types of caicium carbonate and the properties resulting from their use.

W096/052v4 2~9~ ~5 g ' r~

ExampleCalcium Densiyr Energy P Peal; Sti~ness Carbomlle (F/Cc)Conduct: . menmO load (N/m Aggregale (Wim K) t(m~l Failure ~

28.None 0.19 0.044 7 2.9 6.0 3.1 29.Gama 0.22 0.047 6 2.9 5.0 2.5 Sperse 30.Carbital 0.19 0.045 9 3.5 7.0 2.7 31.RO40 0.22 0.46 7 4.1 5.5 2.7 32.Albacar 0.19 0.046 6 4.1 4.0 15 33.Albacar 0.19 0 047 Lo 34.Multifiex 0.25 0.048 6 2.6 5.5 3.1 MM
w/211 35.RX 0.24 0.043 7 2.5 6.0 3.5 3694w/2 Il 36.Heavy 0.24 0.049 6 2.5 5 5 3,5 w/211 37.F~ 3697 0.25 0.048 6 2.5 6.0 3.8 w/211 38.Albacar 0.24 0.045 7 2.5 6.0 3.7 Lo w/211 39.~ntra 0.17 0.045 8 3.7 5.0 2.0 Phlex w/211 The tests revealed that for a 20 weight percent by solids addition of a calcium carbonate aggregate, the mechanical and thermal properties of the resulting cups were only moderately affected by the type of calcium carbonate used. The changes in cup densities were minimal, being no greater than about 10%. The thermal ' ~i~;.;.,~deviated from that ofthe reference cups by only about 5%, i~ ; ofthe type of 20 calcium carbonate used.
The energies-to-failure showed a slightly higher value (about 20%) for Carbital 50 then those of the articles made using other calcium carbonate aggregates, which were aU ay~ / at the same level as the reference cups. The 1 ~ to-failure and peak load were relatively insensitive to the different kinds of calcium carbonate aggregates 25 used except for Albacar. Albacar resulted in the lowest values in these categories. The WO 961~5254 ~ r~

cups that comained 20% calcium carbonale possessed about the same stiffness as the cups - made without an inorganic aggregate. the exception being Albacar and Ultra Phlex, which resulted in cups having about half the stiffness.
l~t general, the different types of calcium carbonate aggregates had similar effects S on the properties of the final cups. The most notab!e exception was Albacar, which had a detrimentaA effect on several properties.

FYA~nl~ 40-44 Cups were made using collamyl starch with different . .., _. .., Al ;. .- ~ - of caAcium 10 carbonate to determine the effect of using collamyl starch. The same procedures and apparatus set forth in Examples 1-13 were used to make and test the cups of Examples 40-44. A base mixture was first prepared by combining the following ~ , by weight:

49.75% collamyl starch and RO40 caAcium carbonate 49.75% water 0-5% magnesium stearate.

The calcium carbonate was added to the mixture in amounts of 20, 40, 50, artd60 % by totaA weight of the calcium carbonate and starch-based binder. ~ ' below are the properties of the articles made using different p.,.1.,11L.~ of calcium carbonate.

25E almplc Cslcium DensityThermal En~ Displace Pe~k Sti9~nesA
Cnrbonrte (g/cc)Conduct. t FNjl ment tolo~d (N) (N/m) Aggregate (W/m K) F~ilure (weight %) (ml) (o/O) 0 0.17 0.043 6 3.5 4.5 1.9 41. 20 0.17 0.043 7 4.3 4.5 1.7 42. 40 0.24 0.046 7 3.5 5.2 2.2 43. 50 0.27 0.045 7 3.2 5.8 2.5 44. 60 0.32 0.053 7 2.6 6.5 3.5 The increase in density was negligible for the first 20% of RO40 calcium carbonate that was added. For higher r,rtn~ l A l;rt~ the increase was substantiaA, being about 2%

~; i ~ ~,~ . . ,=
.,~ . , WO96/0525fi ~ 5g ~ C~

for each weight percent of added R040. Increases in the therrnal conductivity followed a similar pattern as for the density. The increase in thermal Lulwlu~,l;viLy for~ I l. ~. ~ .... A~;~ 1.. of R040 exceeding 20% was about 0.5% per percent of added RO40. The energy and d~ - to-failure for the cups was iargely unaffected by Ihe addition of 5 RO40. The peak load increased lineariy at the rate of about 1% per percent of added RO40. The stiftness curve was similar to the density curve; a relatively flat region up to 20% RO40 and a linear increase for higher f~ ' The rate of increase in stiffness was ~ 1% for each percent of added RO40 in mixtures exceeding 20% RO40.
Based on the above obsavations, coliamyl starch can be used to make the arttclesofthe present invention. rullh~ vle~ relatively high ~ of caicium carbonate can be acided to mixtures containing coliamyl starch without s;~;~..ly reducing the desired mechanicai properties.

FYAm~ni~7~ 45-52 Cups were made using different types of admixtures to determine their effects, if any, on the properties of the mixtures. The same procedures and apparatus set forth in Examples I-13 were used to make and test the cups of the present examples. A base mixture was first prepared by combining the following ~ . by weight:
39.8% Staiok 400 (modified potato starch) 9.95% RO40 calcium carbonate 49 5% water 0.5~/0 magnesium stearate.
Admixtures, including Methocelfi) 240, Tylose@ 15002 and polyvinyl aicohol (PVA), were then combined to the miXIure by weight percentage of the total solids in the mixture. S~m~ ~i7f-~i below is a list of the moldable mixtures and the properties resulting from their use.

W0 961052S4 ~- 21 g ~,~,5 ~, . r - Exsmple Admixtures Densilv Thermal E Dirplace- Pe2k Sti~ess eighl ffo) (~cc) Conduct. Fa8 ment to 108d~fN/m) iW/mK) ( "~ Pailure ~

45. None 0.26 0.045 4 2.2 4.5 2.8 PVA

46. 1.9 0.26 0.046 6 3.1 5.5 2.7 47. 2.9 0.27 0.048 5 2.6 5.5 3.3 48. 3.4 0.26 0.044 4 2.8 5.0 2.8 ~ 240 49. 0.5 0.19 0.045 6 3.4 5.5 2.3 50. 1.0 0.18 0.052 8 6.0 4.5 0.9 Tylose@9 15002 51. 0.5 1 0.23 1 0.044 1 7 1 4.1 1 5.0 1 1.8 52. 1.0 1 0.19 1 0.049 1 3 1 3.1 1 3.5 ~ 1.7 The addition of PVA wss shown to have little effect on the densities, thermal .;...,~" or mechanical properties of the cups made therefrom. Methocel39 240 andTylosei~ 15002 affected the density slightly. The density decreased just over 20% per each addition of 1% of either admixture. The thermal ~,u~ld~l.,L;~ ;.y increased about 10%
20 for the same additions. M~thf '~ 240 had a positive effect on the energy and ~ r~- to-failure n.~ for dry cups. The energy-to-failure values doubled for each 1% addition, whereas the 'i r ' to-failure values showed an ..lly.~, . .
of 2.5 times. The peak load dropped about 20% for each 1% addition of )~ 240, while the stiffness fell more than 70%. A 0.5% addition of Tylose~) 15002 increased the energy-to-failure by 60%. the ~ ,t~ -to-failure by 80% and the peak load by 10%.These incresses Jh...~p~.t:d with a further (0.5%) addition of Tylose(t) 15002. The stiffness of dry cups was halved by additions of 1% of either Methocel~ or Tylose~9.
Generally, PVA was found to have a minimal impact on the properties of the formed cups. Methocel~) 240 and Tylose~ 15002 were found to either maintsin or 30 improve the properties of the cups at lower COIl.,.,.lLl aLiu.~ The benefits, however, were losl as the cf n, ~ . of each was increased.

, ~ , . . .. .. .. .

W0 96/05254 ~ ~, . I u., S
~197~59 , FYArr~ 53-57 To study the synergistic effect of some admixtures~ moldable mixtures were prepared containing ~arying amounts of RO40 caicium carbonate, both with and without the additives Dispex~ A40 and Methocel~ 240. The same procedures and apparatus set for~.h in Examples 1-13 were used to make and test the cups of Examples 53-57. The cups were,made from five different mixtures. Mixture I contained the foiiowing components by weight: 49.75% water, 0.5% magnesium stearate, 19.9% RO40 calcium carbonate, and 29.85% Stalok 400(modified potato starch). Mix I further contained 2%
Dispex and 0.5% MethocelOEv' 240 by weight of the combined starch-based binder and calcium carbonate. Mixture 2 was similar to Mixture 1. except that the percentage of calcium carbonate was increased to 29.85%, while the starch-based binder was decreased to 19.9% . In Mixture 3, the calcium carbonate was further increased to 39.8%, the starch-based binder decreased to 9.95%, and the other .,,...,1.., ;~ kept the same as in Mixture 1. Mixture 4 was similar to Mixture 1, except that Dispex was not added.Finally, Mixture 5 was similar to Mix 3, except that M.~th~ l6 240 was not added.
S ' J below are the properties of the cups made from the five mixtur;es:

Exnmpie MK~e Dersi~y Ih~mal i- t Displace- PenicStifliess (gicc) ConciucL Fii mentto loaci(N/~n) (W/m iC)(mJ) Faiiure ~

53. Mixture 1 0.23 0.049 5 2.9 4.0 1.7 54. Mixture 2 0.25 0.049 3 2.9 3.0 1.3 55. Mixture 3 0.32 0.057 - -56. Mixture 4 0.26 0.044 7 3.5 5.5 2.3 57. Mixture 5 0.32 0.052 4 2.1 3.0 2.1 The tests d . ~ r that the densities of the articles increased as the U AI ;~ of caicium carbonate was increased. The densities of the articles increased, however, if either Dispex A40 or Methocei~v 240 was not included in the mix design. The thermai cunduLlivily exhibited a similar increase with increasing caicium carbonate 30 cun~ Liùn. The energy-to-failure and .1;~ ,. I-to-failure decreased as higherlevels of R040 were included. The samples without Dispex A40 displayed about 30~/0 higher vaiues, whereas the samples produced from a mixture without Methocel~ 240 had siightly lower levels of p~. ru. .,.4..~. The peak load and stiffness both exhibited inferior levels when Dispex A40 and Methocel~ 240 were added to the mixtures W096105254 , ~,, "-,= r~l~L~~
~21Q70~

Aithough the admixtures were useful in producing articles having higher ,f .... ,, ~ of inorganic aggregates, both Dispex M0 and MPt~ 240 produced articles having lower densities and inferior mechanical properties.

5~ F ' 58-62 Cups were made using different smounts of the cross-lir~king admixture Sunrez 74~ to deterrnine its effect on the moldable mixture. The same procedures and sppsratus set forth in Examples 1-13 were used to make and test the cups of Examples 58-62. A
bsse mixture was first prepared by combinmg the following ~ r ' by weight:
28.15% Staiok 400 (modified potato starch) 19.9% RO40 caicium carbonate 1.7% PVA
49.75~/o water 0.5% magnesium stearate.

The base mixture was then varied by i~ incressing the of Sunrez 747 by weight of totai soiids rn the rnr~ure over a range from 2% to 20%.
c. ~ ' below are the i-,~ .,c.,L~.S of Sunrez 747 and the c~ -r ~- _ properties 20 of the resulting cups.

Ex~pie S~ez ~~ tv Th n E~er lo P P'Stiff~o~
747 ~cc)co~iuct F ii mentto loaci(N) (Nlm) (wei~lYc) (W/m K) (n~J) Fuiure 58. 0 0.260.044 4 2.8 4.8 2.5 59. 2 0.250.048 5 2.8 5.0 2.6 60. 5 0.240.048 4 2.8 4.8 2.5 61. 10 0.230.048 7 4.4 4.2 1.5 62. 20 0.240.046 4 3.4 4.0 1.8 ~ .
The tests showed that Sunrez 747 had limited effect on the cup density. Initiaiiy.
the density decressed about 2% for each percent of added Sunrez 747. This ~ eLL;ull~l,ip persisted up to about 5% of the admixture, after which the cup density leveled off. The thermal cûll iu~,Livi~ showed an tnitisi increase of ai~iJIu~ uaiel~ 4% for the first 2% Of ., , _ , ., ~,, .

W0 96/0~2S4 2 1 9 7 ~ 5 ~ 76 ~l/v~.. .
added Sunrez 747, but then leveled out. The mechanicai properties of the cups aiso peaked early with the addition of Sunrez 747. The energy and d:~; S ~ -- to-failure of cups showed oniy minor increases up to 10% and then fell offslightly again. The peak load was fairly level with an apex at 2%. The stiffness curve a~ ' ' a sfep 5 function. There was a plateau where there was no effect of Sunrez 747 addition up to 5~/O. There was a dramatic decrease in sfiffness, roughiy 50%, between 5 and 10%, thereafter the stiffness was not affected. In general, moderate ;...~,.v.. in the various properfies were found where lower ~ of Sunrez 747 were added.

FY~mnl~ 63-70 Five mix designs were evaiuated using varying cull~,G~ aL;u,uo of caicium carbonate (RO40), and different types of starch, in order to determine the minimum processing time and filiing weight at four processing t~ n,.atu.Go (160~C, 180~C, 200~C, and 220~C). As used in the examples, ~ , and appended ciaims, fhe 15 term "processing time" refers to the time necessary to heat the mixfure into a form-stable article. The u, ~ ; ,,. of the five mixtures were as foiiows:

Staiok 400 Hylon VII RO40 Mg Stearate Water ~g) Mixture 1 500 0 0 5 500 Mixture 2 350 50 100 5 450 Mixture 3 300 50 150 5 440 Mixture 4 250 50 200 5 425 Mtxture 5 200 50 250 5 410 Hylon VII Is a type of modlf ed corn starch that was substltuted for parf of theStalok 400. The moldable mixtures were prepared using the procedures sef forth in Example 1-13. Once the mixtures were prepared, a HAAS L13-STA machine was used to make 16 oz. cups having thicknesses of about 4 mm and waffied exteriors. The 30 resulting fiiiing weights and processing times at the seiected t~ .,. atul ~O are as foiiows:

Wo96/0s2s4 z-~g~ IJ~J~ C

Processing Time (sec) Example Temp Mixture I Mixture 2 Mixture 3 Mixture4 Mixture 5 (~C) 63. 220 40 40 40 40 40 64. 200 50 50 50 45 45 65. 180 75 75 75 75 75 66. 160 1~0 170 170 165 160 Filling Weight (g) 10Example Temp.Mixture I Mixture 2 Mixture 3 Mixture 4 Mixture 5 ('C) 67. ''20 30.5 32.2 34.4 37.9 41.6 68. 200 33 31.5 35.6 39.3 43.9 69. 180 31.4 33.5 35.5 37.6 44.1 70. 160 31.7 33.7 34.1 39.7 43.9 As expected, the tests revealed that the processing times decreased as the processing h~ tul~D increased. Although the decrease in processing time was greatest for increases in processing t~ ,.a~ul~,D at the lower ranges, the decrease in processing 20 time was most dramatic where calcium carbonate was included at the higher ranges. The tests also revealed that the minimum filling weight increased with higher of calcium carbonate. However, the filling weight was ~ ~ ' of the mold l.,..p~ ~IUI e.

~To~rlnl~c 71 -78 The same c...~.l.c~ .uc and processing parameters defined in Exarnples 63-70 were used to determine the minimum processing times and filling weights at four processing lelllP~I~iUI~D (160~C, 180~C, 200~C, and 220~C) to produce 12 oz. cups having a smooth surface. The .~A~.~lilll~,...al results ofthe effects on the processing time 30 and minimum filling weight are Dul.llll.lfi~d below.

w0 96~ 1 9 ~ ~ 5 ~

Processin~ lime (sec) Ex7mpleTemp. Mixrure I Mixture 2 Mixmre 3 Mixmre 4 Mixmre s (~c) 71. 220 35 35 35 35 35 72. 200 40 40 40 40 40 73. 180 80 80 80 75 75 74. 160 110 1~0 110 110 110 FiJling Wagh~ ~8) Ex~rnple Temp Mixmre I Mixolre Z Mixmre 3 Mixnlre 4 Mu;~e 5 ( oc) 75. 220 28.7 29.3 33.2 37.5 41 76. 200 28 31.6 33.4 37.5 40.7 77. 180 30.5 31.5 33.8 38.8 42 78. 160 28.2 31.5 36.5 38.2 40 The test revealed findings similar to those outlined above in Examples 63-70.

FY7mrl~c 79-86 The same .. u.,~ and processing parameters defined in Examples 63-70 were used to determine the minimum processing tirnes and filling weights at fourprocessing t~,...!.~Lu..,S (160~C, 180~C, 200~C, and 220~C) to produce "clarn-sheD"
containers having a smooth surface. The ~ ;U.~,...dl results regarding the processing time and minimum filling weight are ~. . , -- ;,. rl below.

WO 96/05254 ~ 9 7-o ~-' 9 ~ - T _ I / u~ ~ \

~ ~9 .. ~ .

Processmg Time (sec) Ex~mple TempMixn~re I Mixnure 2 Mixmre 3 MixnLre 4 Mixmre 5 (=c) 79. 220 30 30 30 30 30 80. 200 35 35 35 35 35 81. 180 45 45 45 45 45 82. 160 50 50 50 50 50 Filling Weight (g~
Exumple Temp. MixD re I Mixmre ~ Mixture3 Mi~e4 Mixmres (oc) 83. 220 19.7 24.1 25.6 29.8 31.2 84. 200 19.0 23.4 24.7 27.8 32.5 85. 180 17.9 23.4 24.6 28.7 30.5 86. 160 17.1 23.4 25.0 28.0 30.5 The tests revealed finding similar to those outlined in Examples 63-70.

FY~"~nlp~ 87-91 Using the same process as in Examples 1-13,12 OZ. CupS were made using dies at a Lt~ L~I~e of 200~C. The mixture for ~ ~ ~ the cup consisted of the foDowing ~~ n~ ~ byweight:

24.95% Stalok 400 (modified potato starch) 19.9% R040 calcium carbonate 4.9% Hylon VlI (modified corn starch) 49 75% water 0.5% magnesium stearate.

The dried cups were placed in a high humidity chamber having a relative humidityof about 95% and a l~ Lul e of about 45 ~C The cups were removed after varying levels of moisture had been absorbed by the starch-bound struchlral matrix of the cups and -- } . _ . . . .

W0 96/052S4 2 ~ 9 7 0 5 Y . ~ .l/U~. , tested to determine their mechanical properties. The respective moisture contents and C~nlC~ ,, mechanical properties are outlined below:

BASE MrxTlJRF-loo/D ~, lnn 40%('5(~Q3 ExmnplesMolsture Conlent Peai~ Load Dispiacement to Energy ~ Failure (ffo) (m~

87. 0 5.5 2.9 5 88. 2 8.5 3.7 12 89. 5.5 10.5 11.& 45 go, 7.5 9.0 23.5 65 91. 9.5 - 24.3 40 The test results reveal a roughiy linear correlation between the moisture content and the mechanica'i properties for low moisture contents. As the moisture content 15 increased, the mechanica'i properties improve, F~,q~nl~c 92-94 Using the same processing parameters set forth in Examples 1-13, 12 oz. cups were made from moldable mixtures having varying p~ lt..5_;~ of ca'icium carbonate and 20 relatively const~tnt viscosities to determine the e~ect of calcium carbonate on the required water content and time for removing the water. S~mqri7~d below are the 4~ .n- ' ;n. --tested and the required times to produce a form-stable article having a finished surface.

Ex_mple Calctutn Stnrch-bnsed Magnesiutn wnter Process Titne Carbonate binder stenrate (g) (sec) (g) (g) (g) 92. 250 250 10 425 50-55 93. 350 150 10 350 35-40 94. 400 100 10 285 30 The results show that with increased ~ - of caicium carbonate, less water is needed to obtain a mixture having a constant viscosity. Fu- lil.,. ImJl ~, as a result of having less water, the required processing time to produce a form-stable article was decreased.

~J096/05254 7 ~9 r.~,. . 5 ~ j~ J ~
- Fr~rnrl~e 95- 114 The same five o~ and baking times set forth in Examples 63-70 were used to make 16 oz. cups having a wafded surface. The dried cups were ~ ty placed on a scale within a humidity chamber at 45 ~C artd a relative humidity of 90D/o, The 5 rate of moisture absorption of the cups was then determined by plotting the weight of the cups as a function of time. S~ d below are tables showing the percent moisture absorption at selected time interv,als for each of the five mixtures. A separate tablc is provided for the cups made at Lt--l,L~ tulco of 160~C, 180~C, 200~C, and 220~C.

Moisture Absorption (weight %) at 160~C
Example compositionsoo (sec) 800 (sec) 1200 (sec) 1600 (sec) 95. Mixture 1 5.0 8.0 11.0 96. Mixture 2 5.0 7.5 10.0 12 97. Mixture 3 3.5 6.0 8.0 10 98. Mixture 4 3.5 5.5 7.5 9 99. Mixture 5 3.0 5.0 6.0 7 Moisture Absorption (weight %) at 180~C
Examplc comporition400 fscc) 800 (sec) 1200 (sec) 1600 (sec) 100. Mixture 1 6.5 11 12 101. Mixture 2 6.0 9.0 11.5 13.5 102. Mixture 3 4 6.5 9.0 11.0 103. Mixture,4 4 6.0 8.0 9.5 104. Mixture 5 2.5 4.5 6.0 7,0 Moisture Absorption weight (%) at 200~C
~Yample Composilion400(sec) 800(sec) 1200(sec) 1600(scc) 105. Mixture 1 5.5 10.0 106. Mixture 2 4.5 7.0 9,0 11.5 107. Mixture 3 4.5 7.0 9 0 11 0 108. Mixture 4 4.5 7.0 8.5 10.0 109. Mixture 5 4.5 . 6.5 8.0 g,o , F~,ll. ~, wo 9610s2s4 .
.

a 5 9 82 Moisture Absorption (weight %) at 220~C
Example Composition 4()0(sec) 800(sec) 1200~sec) 1600~scc) 110. Mixture I 5.0 9.5 13.0 111. Mixture Z 4.5 8.5 11.5 5 112. Mixture 3 4.0 7.0 9.0 11.0 113. Mixture4 4.0 7.0 9.0 11.0 114. Mixture 5 3 0 5.0 6.5 8.0 The tests showed that the rate of moisture absorption decreases for all 10 c~ l,o~ ,c That is, the more moisture contained within an article, the slower the article absorbs additional moisture. The tests also showed that cups having increased ~ 1.... 1 "n ;l ,..~ of calcium carbonate absorb moisture at a lower rate. There is, howcver, no systematic variation on the absorption rates as a function of the different processing L~ Lu~. ~. It is believed that the differences between tables are due to statistical variations.

FY~mnl~c 115-136 The same five mixtures and processing times set forth in Examples 63-70 were used to make 12 oz. cups having a smooth surface. The dried cups were ' , ~, placed on a scale within a humidity chamber at 45~C and a relative humidity of 90~/0. The rate of mois~ure absorption ofthe cups was then determined by plotting the weight of the cups versus time. S~mn~ A below are tables showing the percent moisture absorption at selected time intervals for each of the five mixture. A separate table is provided for the cups made at mold ta~ dtul~ of 160~C, 180~C, 200~C, and 220~C.
Moisture Absorption (weight %) at 160~C
Example Composition 400(s~) 800(sec) 1200(sec) 1600(sec) 115. Mixture I 3.5 6.0 9.0 116. Mixture2 3.5 6.5 9.0 11.0 30 117. Mixture 3 3.5 6.0 8.0 10.0 118. Mixture 4 3.5 6.0 8.0 9.5 119. Mixture 5 3.5 5.5 7.0 8.0 W096/05254 ~ 7~59 r~" s .i ~
83 c"
..
Moisiure Absorption tweight %) at 180~C
Exnmple Composition loo Isec) 800 isecl 1200 (seci 1600 (sec~
120. Mixture 1 4.5 8.0 11.5 121. Mixture 2 3.0 6.0 8.5 10.0 122. Mixture 3 3.0 6 0 8.0 9.5 123. Mixture 4 2.5 5.0 6.5 8.0 124. Mixture 5 1.5 5.0 8.0 9.5 .
Moisture Absorption (weight ~/~) at 200~C
i xample Composiuon 400 (soc) 800 ~sec) i200 (sec~ 1600 (sec~
125. Mixture 1 4.5 8.5 12.0 126. Mixture 2 4.0 7.0 10.0 11.0 127. Mixture 3 3.0 5.5 8.0 10.0 128. Mixture 4 3.0 5.5 7.5 9.0 129. Mixture 5 3.0 5.0 7.0 8.0 . .
Moisture Absorption ~weight ~/o) at 220~C
i-~umple composiuon 400 (sec) 800 (sec) 1200 (scc) 1600 (sec 130. Mixture 1 4.5 3.5 11.5 131. Mixture2 4.0 2.0 10.0 12.0 132. Mixture 3 2.5 5.5 8.0 10.0 133. Mixture 4 2.5 5.5 7.5 8.5 134. Mixture 5 2.0 4.0 6.0 6.5 The tests showed that the rate of moisture absorption decreases for all ~.. pc.~ That is, the more moisture contained within an article, the slower the 30 articles absorb additional moisture. T.he tests also showed that cups having increased - IAl.. ~tlA~ of calcium carbonate absorb moisture at a lower rate. There is, however, no systematic variation of the absorption rates as a function of the different processing tC~y~OiUll;ii-. It is believed that the differences between tables are due to statistical variations.

w096/052~4 r.l,.,.. l .

~,ig~ ~~i9 84 FYa~.~ 135-139 Using the five mixtures set forth in Examples 63-70. 12 oz. cups having a smooth surface were produced using a mold t~ ,u.,. ~Lul ~ of 200~C The cups were ~ 1y placed in a high humidity chamber at 45~C and 90% humidity. Selected cups were 5 p~,i ' "~, removed during the ..uu ~; ;u: ~g stage and tested in order to determine the moisture content necessary to yield an article having a 10 mm ~lisr'- ~ ~ before-faiiure.
A ~''Sr'---- of 10 mm was arbitrarily chosen as providing a cup with a sufflcient amount of damage toierance to make the cup useful. The resulting moisture contents necessary to impart the desired property to the cups at the different mixtures are ' below:

Examples Mixmre Moisture Di.l.l-.. :
Content to Failure ~~/~) (o/o) 135. Mixture 1 8.0 14.7 136. Mixture 2 6.7 14.7 137. Mixture 3 6.1 14.7 138. Mixture 4 5.5 14.7 139. Mixture 5 4.9 14.7 The tests reveaied that as the percentage of caicium carbonate was increased in 20 the mixtures, the required amount of moisture needed to impart the desired ~' s~
to-faiiure decreased. Comparing the present test results with those in Examples 95- 114, shows that, aithough mi~ures having more caicium carbonate absorb moisture at a slower rate, such mixtures require less moisture to obtain the desired properties.

Fy"nl51pc 140-146 Articles were made using different types of calcium carbonate to determine the eaect of the particle size and packing density of the inorganic aggregate. Mixtures were made from three different types of caicium carbonate: Carbitai 75, R040, and Marblend.
The basic chemical ~ for each type of caicium carbonate was the same;
30 however, the particle size rliCtnb~ti~-n average particle size, and naturai packing density (or non L,UIII~JI C.. _ i packing density), as shown below, varied greatly.

WO 96/n5~54 219 ~ ~ 5 ~ -~ ~ i ~

. , - Type of Calcium Averase Par~icle Size Natural Packing Carbona~e (um) Density Carbital 75 2.395 0.3593 5 RO40 40.545 0.6869 Marblend 68.468 0.?368 The gradation for each type of calcium carbonate was as follows:
, .

Gradation of Carbital 75 Sieve Opening Retained Passing (~um) % o/0 1518.000 0.00 100.00 5.470 10.00 90.00 3.043 25.00 75.00 1.583 50.00 50.00 0.862 75.00 25.00 20 0.490 90.00 10.00 Gradation of RO40 Sieve Opening Retained Passing 25 (,um) ~/0 o/O
275.000 0.00 100.00 134.700 10.00 90.00 82.150 25.00 75.00 41.308 50.00 50.00 3014.190 75.00 25.00 2.782 90.00 10 00 .

W0 96/05254 p ~
~1~7059 86, Gradation of Marblend Sieve Opening Retained Passing (l~m) o/O 0/O
1000.00 0.00 100.00 5 338.100 10.00 90.00 212.200 25.00 75 00 36.190 50 00 50.00 12.160 75.00 25.00 3.761 90.00 10.00 These tables show that, of the three types of calcium carbonate tested, Carbital 75 had by far the smallest average particle size and the smallest particle size ~;ctrihlltinn, Marblend had the largest, and RO40 was i ~ ' Each mixture contained one type of calcium carbonate, Stalok 400 potato starch and water, while no mold releasing agent was used. The mixtures were prepared according to the procedures set forth in Examples 1-13 and then placed between molds having a i . aLul~ of about 200~C. The articles were removed from the molds once they had obtained form-stability. The molds were nickel-Teflon coated and had ~ y shapes defined to produce a planer. The formed platters were alJ~ 25 cm long, 18 cm wide, and 3 mm thick. Outhned below are the . , for each mixture, the weight of the final platter, and the processing time.

W09610525~1 21~ 7 O ~ 9 r~

Example Calcium Staiok 400 wuer Planer waglli Prot~Dg Carborate (g) (g) (g) Time (g) (sec) Calcium Carbonate Carbital 75 141 . 200 800 800 32.5 40 Calcium Carbonate RO40 143 700 300 800 30.2 40 Calcium Carbonate Marblend 145 1 700 1300 1 800 1 30.2 1 40 146 ¦ 800 ¦ 200 ¦ 800 ¦ NA ¦ NA

Examples 140 and 141 produced form-stable articles having negligible cracks or 15 defects, although the plates of Example 140 were of somewhat higher quality than those of Example 141. ~t example 142, where the Carbi~al 75 was increased to 30% by weight of the total solids, crack-free, form-stable articles could not be made, regardless of the processing time. Examples 143 and 145 produced form-stab]e atticles having negligible cracks or defects using 70% by weight of total solids RO40 and Marblend. The best 20 articles were formed in Example 145. Crack-free, form-stable articles could not be made in Examples 144 and 146 where the ~ of RO40 and Marblend was increased to 80% by weight of the solids.
The above examples teach that functional articles can be made with higher ~u~ rl ;~ of inorganic aggregate by using an aggregate material which (I) has a 25 larger average diameter (which yields an aggregate material having a lower specific surface area), and (2) which has a greater particle size distribution (which yields an aggregate material having a higher particle packing density). The maximum amount of Carbital 75 that could be used to produce functional articles was 20% by weight of the solids. In ~,u~tJ~l ix,4 functional articles could be made using 70~/~ by weight of either 30 RO40 or Marblend. The difference in the rtln~'~ntr~ti~n of aggregate that could be used is attributed to the fact that RO40 and Marblend had a natural packing density ayyl wdll-a~ twice that of Carbital 75. The difference is further attributed to the fact w0 96/0s2s4 P~
~l9~g that RO40 and Marblend had an average particle size that was AIJln~ / twenty tothirty times larger than Carbital 75.
To illustrate, Carbital 75 had a relatively low packing density of about 0.36. As the ~ dGull of Carbital 75 increased and the cu...,~ ALiull of starch-based binder 5 decreased, ~c~ , the volume of interstitial space between the particles increased.
As a result more of the starch-based binder and water was being used to fill the interstitial space as opposed to coating the particles. r..~Lh~ .u~, since the Carbital 75 had a relatively small average particle size (and, hence, a larger specific surface area), more water and starch-based binder were needed to coat the aggregate parLicles. Eventually, I û when the . of Carbital 75 reached 3 0% by weight of the soGds, the volume of interstitial space was so large that there was insufficient water to adequately disperse the starch-based binder and insufficient starch-based binder to adequately bind the aggregate particles into a ~ ~hlr crack-free structural matrix.
In contrast, the Marblend had a much higher packing density of about û.73 and a 15 larger average particle size Accordingly, even at the higher ~ ;..A of 70%
Marblend by weight of solids, the interstitial space was sufficiently small to permit the starch-based binder and water to adequately bind the aggregate particles into a functional article. At 80% Marblend by weight of soGds, however, the volume of interstitial space was again too large for the starch-based binder and water to adequately bind the aggregate 20 particles into a form-rtable, crack-free structural matrix. However, it would be expected that by using an aggregate having a packing density higher then that of Marblend, an article could be made having an even higher ~ of inorganic aggregates.
lt is also nut~,..JILlly that the viscosity of the mixtures decreased as the of Carbital 75 increased and that the viscosity of the mixtures increased with 25 increased ~ of RO40 and Marblend. As previously discussed, the starch-based binder absorbs the solvent. By replacing a portion of the starch-based binder with an inorganic aggregate, the amount of solvent that would have been absorbed by the starch-based binder is free to lubricate the aggregate particles. However, the inorganic aggregate replacing the starch-based binder also produces interstitial space which must 30 be fiUed by the solvent. Accordingly, if the amount of solvent freed by the removal of the starch-based binder is smaUer than the volume of interstitial space created by the addition of the aggregate, then the viscosity of the mixture increases. This process is iGustrated by the use of Carbital 75 . In contrast, if the amount of solvent freed by the removal of the starch-based binder is larger than the volume of interstitial space created by the addition 35 of more aggregate, then the viscosity of the mixture decreases. This process is iUus~rated by the RO40 and Marblend.

. .

W096/05254 219~59 T~/ 9!' ~, ", ~
~Y~nl~c 147-151 ~ In the foUowing examples~ each of the ~ ~ .,.. J~ ' ' ' was held constant except for the starch-based binder, which was gradually substituted with rice 'dour. Because rice fiour includes a high percentage of starch, along with some protein, it would be expected 5 to have a binding effect within the structural matrix. In addition, the inert fraction would be expected to act as an inert organic filler. All u. ~are expressed as a percentage by weight of the overall mixture.

ExampleStalolc 400 Rice Flour RO40 wa~Magne~um Stwllte 147 24.8% 0~/0 24.8~~ 49.5%0 50/o 148 19.8% 5.0% 24.8% 49.5~/00 50/o 149 14.9~/0 9.9% 24.8% 49.5~/0 0.5~/0 150 9.9% 14.9% 24.8% 49.5~/00.50/o 151 5.0% 19.8% 24.8% 49.5~/0 0.5~/0 The ro~ l o-~ of these examples resulted in molded articles in which the average cell diameter of the cells decreased as the percentage of the rice fiour was 20 increased and the amount of Stalok 400 (potato starch) was decreased. Hence, these examples show that the cell size can be regulated through the use of controlled mixtures of starch-based binder of different origin. This~ in turn, results in articles having different physical and mechanical properties. In this manner, rice 'dour (or similar grain fiours or alternative starch sources~ can be used in varying amounts in order 25 to carefiully control the physical and mechanical properties of the resulting atticles uL~L~ d therefrom. The following are the average cell diameters and skin thicknesses ofthe articles luG~ rh~Lul~d using the mix designs of Examples 147-151:

ExampleAverage CellWall Thickness Shn Thichless 3iAmeter - 30 147 670 um 2.2 mm 300 llm 148 450 llm 2.4 mm 370 um 149 370 ,um 2.5mm 3301um 150 300 llm 2.3 mm 250 llm 151 300 ~m 2.1 mm 200 Llm :.,.. , : .

W0 96/05254 ' ' ' r~

9~
~197~5~
F '- 15' In order to increase the average cell size and skin thickness, moldable mixtures are 5 made which have decreased viscosity, even as low as 50 cps at a shear rate of 100 rpm, by altering the base mixture of 49.75% Stalok 400 and inorganic aggregate (combined), 49 75~/0 water, and 0.5% magnesium stearate. This base mixture has a viscosity of 300 cps at a shear rate of 100 rpm. The viscosity of the mixture can be reduced to 50 cps at the same shear rate by adding more water or through the addition of 1% oil by weight.
Alternatively, in order to decrease the average cell size and skin thickness, the viscosity of the moldable mixture can be increased, even up to 100,000 cps at the same shear rate, through the use of less water and/or the addition of cellulosic thickeners (such as Methocel~)).

EX unple 153 A mixture containing 24.8% Stalok 400, 24.8% inorganic aggregate, 49. 5% water, and 0.5% magnesium stearate is formed by pregelating the starch-based binder prior to the addition ofthe aggregate and mold release agent. The pregelation is carried out either through the use of a precooking step or through the use of a pregelated starch-based 20 binder. The precooking step is carried out by heating the vessel containing the starch-based binder mixture over a heated surface or by ,....,.u....~ the mixture. The yield stress ofthese pregelated mixtures is between about 3 kPa to about 20 kPa. The mixtures produced by this method are fabricated into articles by the same processing techniques used in the foregoing examples for a pourable mixture.
FY~n~pl~c 154-157 Moldable mixtures containing varying amounts of polyvinyl alcohol ("PVA") were used to ,.~..lra~ articles. It was found that the use of PVA decreased the processing time.

W096/05254 2197 05~

9, Ex~nple Starch-based Calcium M~ waterPoivvulyl Process Time ~ biDder Carborlate Stezralc Aicohol iStni ok) ~ 154 500 g 500 g 20 g 883 g1.7 g 45-50 sec 155 500 g 500 g 20 g 917 g3.33 g 40-45 sec 156 500 g 500 g 20 g 950 g5.0 g 4045 sec 5 157 500 g 500 g 20 g 983 g6.7 g 35-40 sec r ~ 158-160 Mixtures were prepared that contained the following ~ r and cuuc~.. l,~Liulls in order to show the effect of solvent ~ on the density and 10 insulation abi'iity of the articles " r cd therefrom.

i xample Potntocnicitlm Cnrbolmle RO40 Magnesium Wnter (g) Starch (g) (g) sleflrate (g) The articles ~-ur~Lu~cai from the mixtures of Examples 158-160 . n~ 1 rfl that using less water resulted in a molded article having smailer cei'is, higher density, and lower insulation (higher thermai conductivityj.
r ~ 161 A study was performed to determine the effect of varying the number of vent holes within the molding apparatus used to r ' C CUpS on the structure of the resulting moldeci cups. The moldable mixture of Example I was formed into cups using different 25 molding apparatus in which the number of vent holes was varied so that there were 2, 4, 6, 8, or 10 vent holes of standard size, respectively. The density of the wa'ils of the - resuiting cups incre~tsed as the number of vcnt holes increased, ~ , because ofthe decrease in pressure that was able to build up, which led to a iower expansion of the cells within the structural matrix of the cup waiis. Hence, using fewer vent holes results in a 30 molded article having wa'il that are less dense and which have larger cells within the structurai matrix.

W096~0~254 F~n~ni~ 162-169 Moldable mix~res are made which have a lightweight aggregate in order to yield a more lightweight article having greater insulation ability and lower density. The mixtures used to form such articies are set forth as follows:

ExDmplePotalo StarchPerlile (xO b~ Magneslum Water (g (g) ~olume of mixturei stGarate (g) ~ ~
The mixtures arc formed into cups using the sy-stems and methods set forth above.
As the amount of perlite is increased, the resulting cup has a lower density, thermal ~.u..Ju~,l.~v;ty, increased stiffness, and increased brittleness. The cups having the optimal balance of the foregoing properties are obtained by using a moldable mixture in the which the CU~ G~ ;UI~ of perlite ranges firom between about 25% to about 55~/0 perlite by volume of the moldable mixture. However, using more or less than these amounts may be desired for certain articles.

VII. SUMMARY
From the foregoing, it wiD be appreciated that the present invention provides improved methods and systems for molding ;~UI L ~ fiDed ~ n l ~ ~ into articles having a variety of shapes presently formed from paper, cardboard, POI.~StYICIIG~ metai, glass, plastic, or other organic materiais.
The present invention fiurther provides improved methods and systems for moldingil~u~ fiDed articles having the desired strength and flexibility for their intended use.
The present invention J '"' '1~/ provides improved methods and systems for molding hlol~ filled articles that can ,1~ ly be formed with a coating.
The present invention also provides improved methods and systems for molding ~ L ~ filled articles that can be fûrmed having a smooth surface.
' Wo 96/05254 21~ 7 ~ ~ 9 . r ~I,u...
~ ~ u l The present invemion also provides improved methods and systems for ", .. ,r ~ i..u~ filled, cellular articles which have propenies similar to those of paper, paperboard, pul ~.Ly~ . metal, glass. and plastic. Such methods can be used to mold such ~: u~ into a v arietv of containers and other objects using slightly S modified, currently existing equipment.
The present invention funher provides improved methods and ~ for l_____ r ' _ illUI~ filled, cellular anicles which do not result in the generation of wastes involved in the IllGllUr.~ UlC~ of paper, paperboard, plastic, metal, glass, or polyst-yrene materials.
The present invention further provides improved methods and ~ U~ for molding ~ ~ which contain less water to be removed during the ". ,r n.. ;. .g process (as compared to paper r ' _) in order to shorten the processing time andreduce the initial equipment capi~al investment. Further, the improved methods and ....,..1...~:1;....~ yield articles that are readily degradable into substances which are nontoxic 15 and which are commonly found in the earth.
In addition, the present invention provides improved methods for molding u....~ into containers and other articles at a cost ~ , and even superior,to existing methods used to ~"~,,~L,LU~ paper or pG~ L~ . articles.
The present invention also provides improved methods for molding ~
20 that are less energy intensive, which conserve valuable natural resources, and which require lower initial capital ~,.,.-,.~,.-l~ compared to those used in making articles from conventional materials.
~ Ldditionally, the present invention provides improved methods for mass-producing il~ulL, "!~ filled, cellular articles which can rapidly be formed and ;L L ".~ dried 25 within a matter of minutes from the beginning of the ~ r_- n ll ;~ 'g process.
Finally, the improved methods allow for the production of highly i..o", ' ".~, fiDed, cellular materials having greater flexibility, flexural strength, toughness, moldability, and mass-producibility compared to materials having a high content of inorganic filler.
The present invention may be embodied in other specific forms without departing from its spirit or essential ~ UG~tI~ L;~ The described ~ o~ are to be - considered in all respects only as iDustrated and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description.
All changes which come ~vithin the meaning and range of equivalency of the claims are to be embraced within their scope What is claimed and desired to be secured by United States Letters Patent is:

Claims (227)

1. An article of manufacture comprising a starch-bound cellular matrix of starch and inorganic aggregate, the starch-bound cellular matrix comprising: a starch-based binder that has been substantially gelatinized by water and then hardened through the removal of a substantial quantity of the water by evaporation; and an inorganic aggregate dispersed throughout the starch-bound cellular matrix in a concentration in a range from about 20% to about 90% by weight of total solids within the starch-bound cellular matrix, wherein the starch-bound cellular matrix has a thickness less than about 1 cm and degrades after prolonged exposure to water.

2. An article of manufacture as defined in claim 1, wherein the starch-based binder includes a potato starch.

3. An article of manufacture as defined in claim 1, wherein the starch-based binder includes a wheat starch.

4. An article of manufacture as defined in claim 1, wherein the starch-based binder is selected from the group consisting of starches derived from cereals, tubers, and roots, and mixtures thereof.

5. An article of manufacture as defined in claim 1, wherein the starch-based binder is derived from a grain flour.

6. An article of manufacture as defined in claim 1, wherein the starch-based binder includes a plurality of different types of starches.

7. An article of manufacture as defined in claim 1, wherein the starch-based binder includes a modified starch.

8. An article of manufacture as defined in claim 1, wherein the starch-based binder is included in an amount in a range from about 10% to about 80% by weight of total solids within the starch-bound cellular matrix.

9. An article of manufacture as defined in claim 1, wherein the starch-based binder is included in an amount in a range from about 30% to about 70% by weight of total solids within the starch-bound cellular matrix.

10. An article of manufacture as defined in claim 1, wherein the starch-based binder is included in an amount in a range from about 40% to about 60% by weightof total solids within the starch-bound cellular matrix.

11. An article of manufacture as defined in claim 1, wherein the inorganic aggregate includes calcium carbonate.

12. An article of manufacture as defined in claim 1, wherein the inorganic aggregate includes sand.

13 . An article of manufacture as defined in claim 1, wherein the inorganic aggregate includes a plurality of different kinds of aggregates.

14. An article of manufacture as defined in claim 1, wherein the inorganic aggregate is selected from the group consisting of sandstone, glass beads, mica, clay, kaolin, limestone, silica, fused silica, alumina, and mixtures thereof.

15. An article of manufacture as defined in claim 1, wherein the inorganic aggregate is selected from the group consisting of perlite, vermiculite, hollow glass spheres aerogel, exfoliated rock, and mixtures thereof.

16. An article of manufacture as defined in claim 1, wherein the inorganic aggregate imparts a color to the mixture.

17. An article of manufacture as defined in claim 1, wherein the inorganic aggregate has a specific surface area in a range from about 0.1 m2/g to about 400 m2/g.

18. An article of manufacture as defined in claim 1, wherein the inorganic aggregate has a specific surface area in a range from about 0.15 m2/g to about 50 m2/g.

19. An article of manufacture as defined in claim 1, wherein the inorganic aggregate has a specific surface area in a range from about 0.2 m2/g to about 2 m2/g.

20. An article of manufacture as defined in claim 1, wherein the inorganic aggregate includes a lightweight aggregate which lowers the thermal conductivity of the article.

21. An article of manufacture as defined in claim 1, wherein the inorganic aggregate is included in an amount in a range from about 30% to about 70% by weight of total solids within the starch-bound cellular matrix.

22. An article of manufacture as defined in claim 1, wherein the inorganic aggregate is included in an amount in a range from about 40% to about 60% by weight of total solids within the starch-bound cellular matrix

23. An article of manufacture as defined in claim 1, wherein the article has a specific heat in a range from about 0.1 J/g~K to about 400 J/g~K at 20°C.

24. An article of manufacture as defined in claim 1, wherein the article has a specific heat in a range between about 0.15 J/g~K to about 50 J/g~K at 20°C.

25 An article of manufacture as defined in claim 1, wherein the article has a specific heat in a range between about 0.2 J/g~K to about 20 J/~g K at 20°C.

26. An article of manufacture as defined in claim 1, wherein the starch-bound cellular matrix further includes a mold-releasing agent.

27. An article of manufacture as defined in claim 26, wherein the mold-releasing agent includes a fatty acid having a carbon chain greater than about C12.

28. An article of manufacture as defined in claim 26, wherein the mold-releasing agent includes a salt of a fatty acid.

29. An article of manufacture as defined in claim 26, wherein the mold-releasing agent includes an acid derivative of a fatty acid.

30. An article of manufacture as defined in claim 26, wherein the mold-releasing agent includes magnesium stearate.

31. An article of manufacture as defined in claim 6, wherein the mold-releasing agent includes a wax.

32 An article of manufacture as defined in claim 26, wherein the mold-releasing agent is included in an amount in a range from about 0.5% to about 10% by weight of total solids within the starch-bound cellular matrix.

33. An article of manufacture as defined in claim 1, wherein the starch-bound cellular matrix further includes fibers dispersed therein.

34. An article of manufacture as defined in claim 33, wherein the fibers are included in an amount in a range from about 0.5% to about 60% by volume of solids within the starch-bound cellular matrix.

35. An article of manufacture as defined in claim 33, wherein the fibers are included in an amount in a range from about 2% to about 40% by volume of solids within the starch-bound cellular matrix.

36. An article of manufacture as defined in claim 33, wherein the fibers are included in an amount in a range from about 5% to about 20% by volume of solids within the starch-bound cellular matrix.

37. An article of manufacture as defined in claim 33, wherein the fibers includes sisal fibers.

38. An article of manufacture as defined in claim 33, wherein the fibers are selected from the group consisting of fibers derived from hemp, cotton, plant, leaves, abaca, bagasse, wood, and mixtures thereof.

39. An article of manufacture as defined in claim 33, wherein the fibers are selected from the group of fibers consisting of glass, graphite, silica, ceramic, metals, and mixtures thereof.

40. An article of manufacture as defined in claim 33, wherein the fibers have an average diameter in a range from about 10 µm to about 100 µm.

41. An article of manufacture as defined in claim 33, wherein the fibers have an average diameter in a range from about 50 µm to about 100 µm.

42. An article of manufacture as defined in claim 1, wherein the starch-bound cellular matrix further includes a rheology-modifying agent.

43. An article of manufacture as defined in claim 42, wherein the rheology-modifying agent includes a cellulose-based material.

44. An article of manufacture as defined in claim 43, wherein the cellulose-based material is selected from the group consisting of methylhydroxyethylcellulose, hydroxymethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose,hydroxyethylcellulose, hydroxyethylpropylcellulose, hydroxypropylmethylcellulose, and mixtures or derivatives thereof.

45. An article of manufacture as defined in claim 42, wherein the rheology-modifying agent includes a polysaccharide-based material.

46. An article of manufacture as defined in claim 45, wherein the polysaccharide-based material is selected from the group consisting of alginic acid, phycocolloids, agar, gum arabic, guar gum, locust bean gum, gum karaya, gum tragacanth, and mixtures or derivatives thereof.

47. An article of manufacture as defined in claim 42, wherein the rheology-modifying agent includes a protein-based material.

48. An article of manufacture as defined in claim 47, wherein the protein-based material is selected from a group consisting of prolamine, collagen, casein, and mixtures or derivatives thereof.

49. A mixture for forming an article of manufacture as defined in claim 42, wherein the rheology-modifying agent includes a synthetic organic material.

50. An article of manufacture as defined in claim 49, wherein the synthetic organic material is selected from the group consisting of polyethylene glycol, polyvinyl alcohol, polyvinyl acetate, polyacrylic acids. polylactic acid, and mixtures or derivatives thereof.

51. An article of manufacture as defined in claim 42, wherein the rheology-modifying agent is included in an amount in a range from about 0.5% to about 10% by weight of total solids within the starch-bound cellular matrix.

52. An article of manufacture as defined in claim 1, wherein the starch-bound cellular matrix further includes a dispersant.

53. An article of manufacture as defined in claim 52, wherein the dispersant is selected from the group consisting of sulphonated melamine-formaldehyde condensate, lignosulfonate, and polyacrylic acid.

54. An article of manufacture as defined in claim 1, wherein the starch-bound cellular matrix further includes an enzyme.

55. An article of manufacture as defined in claim 54, wherein the enzyme is selected from the group consisting of carbohydrases, amylase, oxidase, and mixtures or derivatives thereof.

56. An article of manufacture as defined in claim 54, wherein the enzyme is included in an amount in a range from about 0.5% to about 10% by weight of total solids within the starch-bound cellular matrix.

57. An article of manufacture as defined in claim 1, wherein the starch-bound cellular matrix further includes a humectant for maintaining moisture within the cellular matrix and increasing the flexibility of the article.

58. An article of manufacture as defined in claim 57, wherein the humectant is selected from the group consisting of MgCl2, CaCl2, NaCl, calcium citrate, and mixtures thereof.

59. An article of manufacture as defined in claim 1, wherein the starch-bound cellular matrix includes a cross-linking material.

60. An article of manufacture as defined in claim 59, wherein the crosslinking material is selected from the group consisting of dialdehydes, methylureas, melamine formaldehyde resins, and mixtures or derivatives thereof.

61. An article of manufacture as defined in claim 59, wherein the crosslinking material is included in an amount in a range from about 0.5% to about 5% by weight of total solids within the starch-bound cellular matrix.

62. An article of manufacture as defined in claim 1, wherein the starch-bound cellular matrix has a density in a range from about 0.05 g/cm3 to about 1 g/cm3.

63. An article of manufacture as defined in claim 1, wherein the starch-bound cellular matrix has a density in a range from about 0.1 g/cm3 to about 0.5/g/cm3.

64. An article of manufacture as defined in claim 1, wherein the article comprises a container.

65. An article of manufacture as defined in claim 64, wherein the container is a cup.

66 An article of manufacture as defined in claim 64, wherein the container is a plate.

67. An article of manufacture as defined in claim 64, wherein the container is a clam-shell.

68. An article of manufacture as defined in claim 1, wherein the starch-bound cellular matrix has a thickness in a range from about 0.5 mm to about 6 mm.

69. An article of manufacture as defined in claim 1, wherein the starch-bound cellular matrix has a thickness in a range from about 1 mm to about 3 mm.

70. An article of manufacture as defined in claim 1, wherein the starch-bound cellular matrix further includes a coating on at least a portion of a surface thereof.

71. An article of manufacture as defined in claim 1, wherein the coating includes a wax.

72. An article of manufacture as defined in claim 1, wherein the starch-bound cellular matrix further includes a plasticizer that imparts flexibility to the article.

73. An article of manufacture as defined in claim 72, wherein the plasticizer comprises glycerin.

74. An article of manufacture as defined in claim 72, wherein the plasticizer is selected from the group consisting of monoglycerides, diglycerides, polyethylene glycol, sorbitol, and mixtures or derivatives thereof.

75. An article of manufacture as defined in claim 1, wherein the inorganic aggregate includes a porous inorganic aggregate capable of absorbing water during molding of the article and thereafter releasing the water into the starch-bound cellular matrix after the article has been molded.

76. An article of manufacture as defined in claim 1, wherein the article has a thermal resistance in a range from about 0.04 W/m~K to about 0.2 W/m~K.

77. An article of manufacture as defined in claim 1, wherein the article has a thermal resistance in a range from about 0.04 W/m~K to about 0.06 W/m~K.

78. An article of manufacture as defined in claim 1, wherein the starch-bound cellular matrix further includes an inert organic aggregate.

79. An article of manufacture as defined in claim 78, wherein the inert organic aggregate is selected from the group consisting of seeds, grains, cork, plastic spheres, and mixtures thereof.

80. An article of manufacture as defined in claim 78, wherein the inert organic aggregate is included in an amount in a range from about 5% to about 60% by weight of total solids in starch-bound cellular matrix.

81. An article of manufacture as defined in claim 78, wherein the inert organic aggregate is included in an amount in a range from about 15% to about 50% by weight of total solids in the starch-bound cellular matrix.

82. An article of manufacture as defined in claim 78, wherein the inert organic aggregate is included in an amount in a range from about 25% to about 40% by weight of total solids in the starch-bound cellular matrix.

83. An article of manufacture comprising a starch-bound cellular matrix of starch and inorganic aggregate reinforced with fibers, the starch-bound cellular matrix comprising: a starch-based binder that has been substantially gelatinized by water and then hardened through the removal of a substantial quantity of the water by evaporation;
an inorganic aggregate dispersed throughout the starch-bound cellular matrix andincluded in an amount in a range from about 20% to about 90% by weight of solidswithin the starch-bound cellular matrix; and fibers dispersed throughout the starch-bound cellular matrix and included in an amount in a range from about 2% to about 40% by volume of solids within the starch-bound cellular matrix, wherein the starch-bound cellular matrix has a thickness less than about 6 mm and degrades after prolonged exposure to water.

84. An article of manufacture as defined in claim 83, further including a coating on at least a portion of the article.

85. An article of manufacture as defined in claim 83, wherein the starch-boundcellular matrix further includes glycerin.

86. An article of manufacture as defined in claim 83, wherein the starch-boundcellular matrix further includes a material selected from the group consisting of polyethylene glycol, polyvinyl alcohol, polyvinyl acetate, polyacrylic acids, polylactic acid, sorbitol, and mixtures or derivatives thereof.

87. An article of manufacture comprising a starch-bound cellular matrix of starch and inorganic aggregate reinforced with fibers, the starch-bound cellular matrix comprising: a starch binder selected from the group consisting of potato starch, corn starch, and waxy corn starch, the starch binder having been substantially gelatinized by water and then hardened through the removal of a substantial quantity of the water by evaporation, the starch binder having a concentration in a range from about 30% to about 70% by weight of solids within the starch-bound cellular matrix; an inorganic aggregate dispersed throughout the starch-bound cellular matrix and included in an amount in a range from about 30% to about 70% by weight of solids within the starch-bound cellular matrix; and organic fibers dispersed throughout the starch-bound cellular matrix and included in an amount in a range from about 5% to about 20% by volume of solids within the starch-bound cellular matrix, wherein the starch-bound cellular matrix has a thickness less than about 6 mm and degrades after prolonged exposure to water.

88. An article of manufacture as defined in claim 87, further including a coating on at least a portion of the article.

89. An article of manufacture as defined in claim 87, wherein the starch-bound cellular matrix further includes glycerin.

90. An article of manufacture as defined in claim 87, wherein the starch-bound cellular matrix further includes a material selected from the group consisting of polyethylene glycol, polyvinyl alcohol, polyvinyl acetate, polyacrylic acids, polylactic acid, sorbitol, and mixtures or derivatives thereof.

91. An inorganically filled starch-based mixture for forming an article of manufacture having an inorganically filled starch-bound cellular matrix, the mixture comprising substantially ungelatinized unmodified starch granules, water, and aninorganic aggregate filler included in an amount in a range from about 20% to about 90%
by weight of solids within the starch-based mixture.

92. An inorganically filled starch-based mixture as defined in claim 91, wherein the starch granules comprise unmodified potato starch.

93. An inorganically filled starch-based mixture as defined in claim 91, wherein the starch granules comprise unmodified corn starch.

94. An inorganically filled starch-based mixture as defined in claim 91, wherein the starch granules comprise unmodified waxy corn starch.

95. An inorganically filled starch-based mixture as defined in claim 91, wherein the starch granules are included in an amount in a range from about 10% to about 80% by weight of solids within the starch-based mixture.

96. An inorganically filled starch-based mixture as defined in claim 91, wherein the starch granules are included in an amount in a range from about 30% to about 70% by weight of solids within the starch-based mixture.

97. An inorganically filled starch-based mixture as defined in claim 91, wherein the starch granules are included in an amount in a range from about 40% to about 60% by weight of solids within the starch-based mixture.

98. An inorganically filled starch-based mixture as defined in claim 91, further including an alcohol.

99. Art inorganically filled starch-based mixture as defined in claim 91, wherein the water has a concentration in a range from about 20% to about 70% by weight of the mixture.

100. An inorganically filled starch-based mixture as defined in claim 91, wherein the water has a concentration in a range from about 40% to about 60% by weight of the mixture.

101. An inorganically filled starch-based mixture as defined in claim 91, wherein the inorganic aggregate filler comprises calcium carbonate.

102. An inorganically filled starch-based mixture as defined in claim 91, wherein the inorganic aggregate filler comprises sand.

103. An inorganically filled starch-based mixture as defined in claim 91, wherein the inorganic aggregate filler is selected from the group consisting of sandstone, glass beads, mica, clay, kaolin, limestone, silica, fused silica, alumina, and mixtures thereof.

104. An inorganically filled starch-based mixture as defined in claim 91, wherein the inorganic aggregate filler is selected from the group consisting of perlite, vermiculite, hollow glass spheres, aerogel, exfoliated rock, and mixtures thereof.

105. An inorganically filled starch-based mixture as defined in claim 91, wherein the inorganic aggregate has a specific surface area in a range from about 0.1 m2/g to about 400 m2/g.

106. An inorganically filled starch-based mixture as defined in claim 91, wherein the inorganic aggregate has a specific surface area in a range from about 0.15 m2/g to about 50 m2/g.

107. An inorganically filled starch-based mixture as defined in claim 91, wherein the inorganic aggregate has a specific surface area in a range from about 0.2 m2/g to about 2 m2/g.

108. An inorganically filled starch-based mixture as defined in claim 91, wherein the inorganic aggregate is included in an amount in a range from about 30% to about 70% by weight of solids within the starch-based mixture.

109. An inorganically filled starch-based mixture as defined in claim 91, wherein the inorganic aggregate is included in an amount in a range from about 40% to about 60% by weight of solids within the starch-based mixture.

110. An inorganically filled starch-based mixture as defined in claim 91, further including a mold-releasing agent.

111. An inorganically filled starch-based mixture as defined in claim 110, wherein the mold-releasing agent includes a fatty acid having a carbon chain greater than about C12.

112. An inorganically filled starch-based mixture as defined in claim 110, wherein the mold-releasing agent includes a salt of a fatty acid.

113. An inorganically filled starch-based mixture as defined in claim 110, wherein the mold-releasing agent includes an acid derivative of a fatty acid.

114. An inorganically filled starch-based mixture as defined in claim 110, wherein the mold-releasing agent includes magnesium stearate.

115. An inorganically filled starch-based mixture as defined in claim 110, wherein the mold-releasing agent includes a wax.

116. An inorganically filled starch-based mixture as defined in claim 110, wherein the mold-releasing agent is included in a range from about 0.5% to about 10%
by weight of solids within the mixture.

117. An inorganically filled starch-based mixture as defined in claim 91, further including fibers dispersed therein.

118. A inorganically filled starch-based mixture as defined in claim 117, wherein the fibers are included in an amount in a range from about 0.5% to about 60%
by volume of solids within the starch-based mixture.

119. A inorganically filled starch-based mixture as defined in claim 117, wherein the fibers are included in an amount in a range from about 2% to about 40% by volume of solids within the starch-based mixture.

120. An inorganically filled starch-based mixture as defined in claim 117, wherein the fibers are included in an amount in a range from about 5% to about 20% by volume of solids within the starch-based mixture.

121. An inorganically filled starch-based mixture as defined in claim 117, wherein the fibers include sisal fibers.

122. An inorganically filled starch-based mixture as defined in claim 117, wherein the fibers are selected from the group consisting of fibers derived from hemp, cotton, plant, leaves, abaca, bagasse, wood, and mixtures thereof.

123. An inorganically filled starch-based mixture as defined in claim 117, wherein the fibers are selected from the group consisting of fibers derived from glass, graphite, silica, ceramic, metals, and mixtures thereof.

124. An inorganically filled starch-based mixture as defined in claim 91, further including a rheology-modifying agent.

125. An inorganically filled starch-based mixture as defined in claim 124, wherein the rheology-modifying agent includes a cellulose-based material.

126. An inorganically filled starch-based mixture as defined in claim 125, wherein the cellulose-based material is selected from the group consisting of methylhydroxyethylcellulose, hydroxymethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxyethylpropylcellulose, hydroxypropylmethylcellulose, and mixtures or derivatives thereof.

127. An inorganically filled starch-based mixture as defined in claim 124, wherein the rheology-modifying agent includes a polysaccharide-based material.

128. An inorganically filled starch-based mixture as defined in claim 127, wherein the polysaccharide-based material is selected from the group consisting of alginic acid, phycocolloids, agar, gum arabic, guar gum, locust bean gum, gum karaya, gum tragacanth, and mixtures or derivatives thereof.

129. An inorganically filled starch-based mixture as defined in claim 124, wherein the rheology-modifying agent includes a protein-based material.

130. An inorganically filled starch-based mixture as defined in claim 129, wherein the protein-based material is selected from a group consisting of prolamine, collagen, casein, and mixtures or derivatives thereof.

131. An inorganically filled starch-based mixture as defined in claim 124, wherein the rheology-modifying agent includes a synthetic organic material.

132. An inorganically filled starch-based mixture as defined in claim 131, wherein the synthetic organic material is selected from the group consisting of polyethylene glycol, polyvinyl alcohol, polyvinyl acetate, polyacrylic acids, polylactic acid, arid mixtures or derivatives thereof.

133. An inorganically filled starch-based mixture as defined in claim 124, wherein the rheology-modifying agent is included in an amount in a range from about 0.5% to about 10% by weight of solids within the starch-based mixture.

134. An inorganically filled starch-based mixture as defined in claim 91, further including a dispersant.

135. An inorganically filled starch-based mixture as defined in claim 91, further including an enzyme.

136. An inorganically filled starch-based mixture as defined in claim 135, wherein the enzyme is selected from the group consisting of carbohydrases, amylase, oxidase, and mixtures or derivatives thereof.

137. An inorganically filled starch-based mixture as defined in claim 91, further including a humectant for maintaining moisture and flexibility within the article of manufacture.

138. An inorganically filled starch-based mixture as defined in claim 137, wherein the humectant is selected from the group consisting of MgCl2, CaCl2, NaCl, calcium citrate, and mixtures thereof.

139. An inorganically filled starch-based mixture as defined in claim 91, further including a cross-linking agent.

140. An inorganically filled starch-based mixture as defined in claim 139, wherein the cross-linking agent is selected from the group consisting of dialdehydes, methylureas, melamine formaldehyde resins, and mixtures or derivatives thereof.

141. An inorganically filled starch-based mixture as defined in claim 139, wherein the cross-linking agent is included in an amount in a range from about 0.5% to about 5% by weight of solids within the starch-based mixture.

142. An inorganically filled starch-based mixture as defined in claim 91, having a viscosity in a range from about 0.01 Pa~s to about 300 Pa~s.

143. An inorganically filled starch-based mixture as defined in claim 91, having a viscosity in a range from about 0.05 Pa~s to about 30 Pa~s.

144. An inorganically filled starch-based mixture as defined in claim 91, having a viscosity in a range from about 0.2 Pa~s to about 3 Pa~s.

145. An inorganically filled starch-based mixture as defined in claim 91, further including a material capable of forming a coating on at least a portion of a surface of the article of material upon molding the starch-based mixture within a heatedmold.

146. An inorganically filled starch-based mixture as defined in claim 145, wherein the material capable of forming a coating includes a wax.

147. An inorganically filled starch-based mixture as defined in claim 91, further including a plasticizer.

148. An inorganically filled starch-based mixture as defined in claim 147, wherein the plasticizer comprises glycerin.

149. An inorganically filled starch-based mixture as defined in claim 147, wherein the plasticizer is selected from the group consisting of monoglycerides,diglycerides, polyethylene glycol, sorbitol, and mixtures or derivatives thereof.

150. An inorganically filled starch-based mixture as defined in claim 91, further including pregelatinized starch.

151. An inorganically filled starch-based mixture for forming an article of manufacture having an inorganically filled starch-bound cellular matrix reinforced with fibers, the mixture comprising substantially ungelatinized unmodified starch granules, water, an inorganic aggregate filler included in an amount in a range from about 20% to about 90% by weight of solids within the starch-based mixture, and fibers dispersed throughout the starch-based composition in an amount in a range from about 2% to about 40% by volume of solids within the starch-based mixture.

152. An inorganically filled starch-based mixture as defined in claim 151, wherein the inorganic aggregate filler is included in an amount in a range from about 30% to about 70% by weight of solids within the starch-based mixture.

153. An inorganically filled starch-based mixture as defined in claim 151, wherein the inorganic aggregate filler is included in an amount in a range from about 40% to about 60% by weight of solids within the starch-based mixture.

154. An inorganically filled starch-based mixture as defined in claim 151, wherein the fibers are included in an amount in a range from about 5% to about 20% by volume of solids within the starch-based mixture.

155. An inorganically filled starch-based mixture for forming an article of manufacture having an inorganically filled starch-bound cellular matrix reinforced with fibers, the mixture comprising water, substantially ungelatinized unmodified starch granules included in an amount in a range from about 30% to about 70% by weight of solids within the starch-based mixture, an inorganic aggregate filler included in an amount in a range from about 30% to about 70% by weight of solids within the starch-based mixture, organic fibers dispersed throughout the starch-based composition in an amount in a range from about 5% to about 20% by volume of solids within the starch-based mixture, and a mold release agent.

156. An inorganically filled starch-based mixture as defined in claim 155, further including pregelatinized starch.

157. A method for manufacturing an article of manufacture having a cellular structural matrix, the method comprising the steps of:

a. preparing a moldable mixture including a starch-based binder, solvent capable of substantially gelating the starch-based binder, and an inorganic aggregate, the inorganic aggregate being present in an amount in a range from about 20% to about 90% by weight of the total solids in the moldable mixture;
b. positioning the moldable mixture between a male mold and a female mold, the male mold and the female mold having complementary shapes and defining a space therebetween corresponding to a desired shape of the article of manufacture; and c. heating the moldable mixture between the male mold and the female mold in order to remove a substantial portion of the solvent by evaporation from the moldable mixture and to form the cellular structural matrix of the article, wherein the cellular structural matrix has a thickness less than about 1 cm.

158. A method for manufacturing an article as defined in claim 157, wherein the starch-based binder includes a potato starch.

159. A method for manufacturing an article as defined in claim 157, wherein the starch-based binder is selected from the group consisting of starches derived from cereals, tubers, roots, and mixtures thereof.

160. A method for manufacturing an article as defined in claim 157, wherein the starch-based binder is present in an amount in a range from about 30% to about 70% by weight of the total solids in the moldable mixture.

161. A method for manufacturing an article as defined in claim 157, wherein the solvent includes water.

162. A method for manufacturing an article as defined in claim 157, wherein the solvent includes both water and alcohol.

163. A method for manufacturing an article as defined in claim 157, wherein the solvent is present in an amount in a range from about 20% to about 70% by weight of the mixture.

164. A method for manufacturing an article as defined in claim 157, wherein the inorganic aggregate includes calcium carbonate.

165. A method for manufacturing an article as defined in claim 157, wherein the inorganic aggregate includes sand.

166. A method for manufacturing an article as defined in claim 157, wherein the inorganic aggregate includes a plurality of differently sized aggregate particles.

167. A method for manufacturing an article as defined in claim 166, wherein the differently sized aggregate particles are selected to have a packing density in a range from about 0.5 to about 0.9.

168. A method for manufacturing an article as defined in claim 157, wherein the inorganic aggregate has a specific surface area in a range from about 0.15 m2/g to about 50 m2/g.

169. A method for manufacturing an article as defined in claim 157, wherein the inorganic aggregate is present in an amount in a range from about 20% to about 90% by weight of the total solids in the moldable mixture.

170. A method for manufacturing an article as defined in claim 157, wherein the inorganic aggregate is present in an amount in a range from about 30% to about 70% by weight of the total solids in the moldable mixture.

171. A method for manufacturing an article as defined in claim 157, wherein the inorganic aggregate is present in an amount in a range from about 40% to about 60% by weight of the total solids in the moldable mixture.

172. A method for manufacturing an article as defined in claim 157, wherein the inorganic aggregate is added in an amount sufficient to produce an article having a specific heat in a range from about 0.15 J/g~K to about 50 J/g~K at 20°C.

173. A method for manufacturing an article as defined in claim 157, wherein the step of preparing further includes adding a mold releasing agent to the moldable mixture.

174. A method for manufacturing an article as defined in claim 173, wherein the mold releasing agent includes a fatty acid having a carbon chain greater than C12.

175. A method for manufacturing an article as defined in claim 173, wherein the mold releasing agent includes a salt of a fatty acid.

176. A method for manufacturing an article as defined in claim 173, wherein the mold releasing agent includes an acid derivative of a fatty acid.

177. A method for manufacturing an article as defined in claim 173, wherein the mold releasing agent includes magnesium stearate.

178. A method for manufacturing an article as defined in claim 173, wherein the mold releasing agent includes a wax.

179. A method for manufacturing an article as defined in claim 157, wherein the step of preparing includes adding a fibrous material to the moldable mixture.

180. A method for manufacturing an article as defined in claim 157, wherein the step of preparing includes adding a rheology-modifying agent to the moldable mixture.

181. A method for manufacturing an article as defined in claim 180, wherein the rheology-modifyng agent includes a cellulose-based material.

182. A method for manufacturing an article as defined in claim 180, wherein the rheology-modifying agent includes a polysaccharide-based material.

183. A method for manufacturing an article as defined in claim 180, wherein the rheology-modifying agent includes a protein-based material.

184. A method for manufacturing an article as defined in claim 180, wherein the rheology-modifng agent includes a synthetic organic material.

185. A method for manufacturing an article as defined in claim 157, wherein the step of preparing includes adding a dispersant to the moldable mixture.

186. A method for manufacturing an article as defined in claim 157, wherein the step of preparing includes adding an enzyme to the moldable mixture to increase the rate of gelation of the starch-based binder.

187. A method for manufacturing an article as defined in claim 157, wherein the step of preparing includes adding a humectant to the moldable mixture to improve retainage of moisture within the cellular structural matrix.

188. A method for manufacturing an article as defined in claim 157, wherein the step of preparing includes adding a cross-linking material to the moldable mixture.

189. A method for manufacturing an article as defined in claim 157, wherein the step of preparing is performed using a high energy mixer.

190. A method for manufacturing an article as defined in claim 157, wherein the step of preparing is performed using a dual chamber extruder.

191. A method for manufacturing an article as defined in claim 157, wherein the step of preparing includes applying a negative pressure to the moldable mixture to remove entrapped air within the moldable mixture.

192. A method for manufacturing an article as defined in claim 157, wherein the step of preparing further includes heating the moldable mixture to the point of gelation of the starch-based binder.

193. A method for manufacturing an article as defined in claim 157, wherein the step of positioning is performed using a reciprocating screw injector.

194. A method for manufacturing an article as defined in claim 157, wherein the step of positioning is performed using a two-stage injector.

195. A method for manufacturing an article as defined in claim 157, wherein the moldable mixture is formed into a container.

196. A method for manufacturing an article as defined in claim 195, wherein the container is a cup.

197. A method for manufacturing an article as defined in claim 195, wherein the container is a plate.

198. A method for manufacturing an article as defined in claim 195, wherein the container is a "clam shell" container.

199. A method for manufacturing an article as defined in claim 157, wherein the male mold and the female mold have polished surfaces.

200. A method for manufacturing an article as defined in claim 157, wherein the male mold and the female mold have chrome surfaces.

201. A method for manufacturing an article as defined in claim 157, wherein the male mold and the female mold have Teflon nickel coatings.

202. A method for manufacturing an article as defined in claim 157, wherein the step of positioning includes the steps of:

a. placing the male mold vertically above the female mold;
b. positioning the moldable mixture within the female mold; and c. mating the male mold and female mold to encase the moldable mixture.

203. A method for manufacturing an article as defined in claim 157 wherein the step of positioning includes the steps of:

a. placing the female mold vertically above the male mold;
b. mating the male mold and female mold in a complementary fashion to form a mold area between the male mold and female mold; and c. filling at least part of the mold area with the moldable mixture.

204. A method for manufacturing an article as defined in claim 157, wherein the male mold and female mold have at least one vent hole through which the evaporating solvent may escape.

205. A method for manufacturing an article as defined in claim 157, wherein the male mold and the female mold have a plurality of vent holes.

206. A method for manufacturing an article as defined in claim 157, wherein the step of heating the moldable mixture includes heating the male mold and the female mold to a desired temperature.

207. A method for manufacturing an article as defined in claim 206, wherein the mold temperature of the male die and the femal die is in a range from about 150°C to about 220°C.

208. A method for manufacturing an article as defined in claim 206, wherein the temperature of the male mold and the female mold is in a range from about 170°C to about 210°C.

209. A method for manufacturing an article as defined in claim 206, wherein temperature of the male mold and the female mold is in a range from about 190°C to about 200°C.

210. A method for manufacturing an article as defined in claim 157, wherein the step of heating includes increasing the pressure on the moldable mixture positioned between the male mold and the female mold above atmospheric pressure.

211. A method for manufacturing an article as defined in claim 157, wherein the temperature of the male mold and the female mold varies along the length of the molds.

212. A method for manufacturing an article as defined in claim 157, wherein the cellular structural matrix of the article is form-stable within a period of time in a range from about 1 second to about 10 minutes.

213. A method for manufacturing an article as defined in claim 157, wherein the cellular structural matrix of the article is form-stable within a period of time in a range from about 15 seconds to about 5 minutes.

214. A method for manufacturing an article as defined in claim 157, wherein the cellular structural matrix of the article is form-stable within a period of time in a range from about 30 seconds to about 1 minute.

215. A method for manufacturing an article as defined in claim 157, wherein the article has a density in a range from about 0.1 g/cm3 to about 2.5 g/cm3.

216. A method for manufacturing an article as defined in claim 157, wherein the article has a thickness in a range from about 2 mm to about 5 mm.

217. A method for manufacturing an article as defined in claim 157, wherein the method includes the step of conditioning the form-stable article in a humidity chamber.

218. A method for manufacturing an article as defined in claim 217, wherein the humidity chamber has a temperature in a range from about 30°C to about 60°C.

219. A method for manufacturing an article as defined in claim 217, wherein the humidity chamber has a temperature in a range from about 35°C to about 55°C.

220. A method for manufacturing an article as defined in claim 217, wherein the humidity chamber has a relative humidity in a range from about 50% to about 95%.

221. A method for manufacturing an article as defined in claim 217, wherein the humidity chamber has a relative humidity in a range from about 85% to about 95%.

222. A method for manufacturing an article as defined in claim 151, wherein the method includes the step of allowing the form-stable article to obtain a moisture content in a range from about 2% to about 20%.

223. A method for manufacturing an article as defined in claim 217, wherein the article is left in the humidity chamber for a period of time in a range from about 1 minute to about 30 minutes.

224. A method for manufacturing an article as defined in claim 217, wherein the article is left in the humidity chamber for a period of time in a range from about 5 minutes to about 15 minutes.

225. A method for manufacturing an article as defined in claim 157, wherein the method comprises the step of applying a coating to the form-stable article.

226. A method for manufacturing an article as defined in claim 157, wherein the method comprises the step of applying printing to the form-stable article.

227. A method for manufacturing an article of manufacture having a cellular structural matrix, the method comprising the steps of:

a. preparing a moldable mixture including a starch-based binder, solvent capable of substantially gelating the starch-based binder, and an inorganic aggregate, the inorganic aggregate being present in an amount in a range from about 30% to about 90% by weight of the total solids in the moldable mixture;
b. positioning the moldable mixture between a male mold and a female mold, the male mold and the female mold having complementary shapes and defining a space therebetween corresponding to a desired shape of the article of manufacture, and c. heating the moldable mixture between the male mold and the female mold in order to remove a substantial portion of the solvent by evaporation from the moldable mixture and to form the cellular structural matrix of the article, wherein the cellular structural matrix has a thickness less than about 1 cm.