US1786781A - Cloth-like fabric - Google Patents

Description

D 30, 1930. M. .1. SHOEMAKER 1,786,781

CLOTH LIKE FABRI C Filed Aug. 15, 1928 Cellulose Patented Dec. o0, 1930 uNiTED MILTON J. snommxaa, or MADISON, wIsCoNsmQAssIeNon fro o. F.' Buneinssm- A oaA'ronIEs, INC., or mAnrsoN, wIscoNsIN, A CORPORATION or .DELAWARE t f v1.786.731v

rA,"I'i'z'lsrl.'l orales.

onora-LIKE FABRIC Animation mea august 1s, 192s. swarm. 299,454.

This invention relates tothe production and composition of cloth-like fabrics probeatin Furthermore, 'the fabric which is described and claimed maybe washed in the usual way without disintegration. Y

At the presenttime` towels are made 'of paper but such towels are without strength when wet and must bediscarded after being used. The resistance to disintegration by water of such towels may be increased by' hydrating some of the pulp by prolonged This increased-resistance todisinte ration is obtained, however, at a sacrifice o pliability and speed of absorption of vwater. Such towels'cannot be used as wash cloths. Consequently wash cloths are made almost exclusively of knitted or woven fabrics. With my process'l produce a satisfacl' tory wash cloth from unwovenfibers, which need not be Ahydrated mechanically.

Ordinary fibers, especially cellulose bers such as wood pulp, when felted into a sheet, such as a soft absorbent paper, have little strength when wet withwater. Such a paper may be coated with a sizingmaterial or a varnish "to increase the water resistance.

-However, the water absorption is decreased` thereby as varnishes, lacquers and the like are water repellents. The utility of the product isdecreased thereby. If viscose or other cellulose ester is substituted for varnish ,and the like and the cellulose then regenerated in the'usual manner, the vfibers are held in an insoluble mass of regenerated cellulose which' does not disintegratein water. In contrast to the water-repellent nature of varnish, lacquer and the like, the regenerated cellulose is water-absorbent so that'the impregnated sheet loses little or noneof *this desirable ,this is desirable.

property.l However, if the sheet is coated over its entire surface the resultin product 1s not soft, pliable, but is stiff an crackles much like paper. By applying the cellulose ester -in -discontinuous films as hereinafter described, a soft and pliable cloth-1ike prod# uct results.

' Thev discontinuousv cellulose films' may be -obtainedby applying' cellulose dissolved in appropriate solvents or as acellulose ester,

ether or lother compound from which the cel" lulose is subsequently regenerated.. Viscose is a very Icheap. and suitable forml of cellulose wherewith to attain-objects of this inventionl Viscose is prepared Iin solutions of varying concentrations but for the purposes" of this csf invention it is best used as a viscous solution' containing about 7 of cellulose, 6% of caustic soda anda salt index of 3 to 4. However, other concentrations and qualities 'may bc used. "The properties -of the'cellulo'se ester slowly penetrate l.the sheet without iooding.'

The fibers which are 'used are preferably vcellulosic.l Wood fibers are especially suitl' able because of theircheapness and avail lare' variedv to" suit the'fib'rous lproduct which is to be impregnated lbut should in general ability. Since the product 1s to be Water'lxbi sorbent it isbest to use sheets vof wood fibers` or pulp which contain little or no sizing and which are not calendered. It is also preferable to use a long-fibered stock for reasons which will become apparent as'the process is described further. `Long fibered pulp may be made from spruce, tamarack` or jack pine. Spruce is especially suitable since it not only is long fibered but it yields when bleached, a product of high white color which is'usually desirable. If the pulp is mercerized the ,ab-

sorption lis increased as the alpha cellulose fibers swell. Its pliability also increases and In the accompanying drawings the invention is illustrated by one exemplary embodif ment thereof, butit will bennderstood that the invention is not to belconsidered as limited by the illustrated 'disclosurem Fig. 1 is an illustrationV of the simplest form of my invention with aportion broken away and somewhat further enlarged more clearly to 'show the structure of the sheet.

Fig. 2 is a transverse sectional view of the sheet shown in Fig. 1, alon line 2-2 thereof and along line 2-2 of igure 3.

Fig.-3 is a sectional View along lines 3--3 Fig. 4 is a transverse sectional View of a composite sheet comprising two of the sheets of Fig. 1 superimposed upon each other.

Fig. 5 isa sectional view along lines 5-5 of Fi 4.

ig. 6 is a transverse sectional view of a modified form of my invention Fig. 7 's a sectional view along lines 7-7 f Fig. 6'.

To make a thin product suitable for towels or na kins, I use for the base a thin sheet 1 of sultable fibers such as bleached sulphite pulp. A sheet weighing from .07 to .09 lbs. per square yard g1ves excellent results. I coat this sheet with a discontinuous film of viscose preferably of 'the concentration and quality hereinbe'fore described. The discontinuous film may be produced in any one of a number of ways. I prefer applying it in the form of lines 2 by means of a corrugated roller, the ridges applying the cellulose ester to the sheet. For the above long fiberechsulphite pulp a coaterl of 12lines per inch with ridges'..025 inches wide may be used with a viscose of the previously at one or the other end in the contiguous lines. of impregnating cellulose ester. The lines may be straight as shown or they may be in the form of curves or any other desired configuration or pattern. The viscose may alsovbe applied inv the .form of a series of dots. lOther methods will suggest them- I do not scribed but comprehend any method which gives a product which has the ester or soluble cellulose distributed di'scontinuously throughoutthe sheet forming fibrous areas,

substantially free from the ester, most of the fibers in the unimpregna'ted areas being anchored by contiguous portions of the ester.

Although a suitable product may be made by impregnating the pulp sheet on one side inl discontinuous areas with a cellulose ester such as viscose, I prefer to impregnate both sides of the sheet in a similar manner. If one side of the 'sheet has been impre ated with parallel lines of viscose as herein efore described and'as illustrated in Fig. 2, I than impregnate the other side in the Sad la] escribed quality. vThe viscose is thereby applied discontinlthe maximum dimension of the unimpregnated areas is at most equal to'the`average length of the fibers.

The impregnated through the various'baths for regenerating and washing the cellulose'as is well known to those skilled in the art. In regenerating the cellulose from viscose I prefer passing the sheet into a bath containing 1% to 2% of sulphuric acid plus 15% to 20% of sodium sulphate to coagulate the viscose. An ammonium sulphate bath may be used followed by a dilute mineral acid bath instead of the above bath. The cellulose isthereby regenerated from the ester in a highly hydrated condition. The fabric is then passed into about 0.2% caustic soda after which it is washed in Water. It is then bleached in a weak sodium hypochlorite bath containing 0.1%to 0.2% available chlorine followed by 0.5% to 1.0% hydrochloric acid. It is again washed with water. The fabric may be dried but I prefer to pass it through an emollient bath. Various emollients may be used, such as glycerine alone, or associated with other materials, parafline, oil, etc. I prefer to use a bath containing about 1% ivory soap, 2% sulphonatedcastor oil and 4% glycerine. The fabric retains a small portion of this emollient which `softens it, thereby producing a fabric with a soft cloth-like texture.

The fabric is driedeither before or after passing 1t through the emollient solution.` It 1s first squeezed as dry as possible. I prefer to dry it under slight tension. If it is allowed to dry without any tension-the shrinking of 'the regenerated cellulose causes it to have a rough, wrinkled appearance. If` it is dried l under high tension the fabric has a flat paperlike appearance. If dried under slight tension it stays flat but the greater shrinkage of the regenerated cellulose causesit to be depressed below the surface of the unimpreg- `nated areas of fibers as shown at' points 5 1n Fig. 2 and the corresponding points in Figs. 3, 5 and 7. .This gives the fabric a pleasin appearance and a feel similar to a woven fa ric, which is desirable. Thefabric may be colored and embossed to give pleasing effects similar to those on woven fabrics.

A paper towel made in the above manner has a decided advantage over ordinary aper towels in that it is non-linting, highlly) absorbent, and has a higher wet. strength. Such a towel made from thin pulp sheets weighing from .07 to .0 9 lbs. per square yard may consheet is then passed tain from .O to 8.0 grams of regenerated cel lt llose per square yard, when coated on both si ment the-several sheets together.4 A heavy single fabric of fibers cannot be impregnated thoroughly without flooding the top surface -as the cellulose ester travels more readily alongv the surface fibers which are in general in parallel relation to the surface of the sheet. Such a heavy fabric may therefore have an unsaturated plane in the center along which it will cleave readily when used in the wet condition. The impregnating agent should penetrate sufficiently inward from the' surface toward the opposite surface to prevent i such cleavage.

In one method of carrying out my invention in which the hereinbefore described viscous viscose is usedl as the cellulose ester in conjunction with a-plurality of cellulosic fiber sheets, I prefer using a heavier sheet 9 (see Figs. 6 and 7 of pulp as the fabric base than those previously described. Instead of using a pulp sheet, which is preferably mercerized bleached sulphitestock, of .07 to .09 lbs. per square yard, I use a sheet weighing from .15 to .17 lbs. per square yard. I pass this d heavier vsheet through the hereinbefore described coater and'line or otherwise coat one side of said pulp sheet with discontinuous films 11 of cellulose ester. A second sheet 10 of similar pulp but weighing .07 to .O9 lbs. per square yard is then placed on the coated side of said heavier first sheet and said stacked sheets are then passed through squeeze rolls which cause the two sheets to adhere firmly to each other since the cellulose ester on the heavier sheet penetrates the fibers of the thinner sheet and causes adherence between the two sheets.

The above composite sheet is then passed through the coater to line or otherwise coat the two outside surfaces with films l2 of ester, the pattern preferably being applied in a di,- rection at right angles to the first coat. This insures the proper anchoring of the fibers in the unimpregnated areas. The sheet may then be passed through cellulose regenerat` ing, washing and other baths as described previously. Instead of using but two pulp sheets, additional thin sheets of pulp may be added by the same method before regeneration, and the fabric built up by the same procedure into any desired thickness. Two

sheets, one thick and one thin, are sufficient to serve as a wash cloth. Byvthis method the final product consists of a plurality of sheets of unwoven fibers which have a reenforcement comprising regenerated cellu-A lose distributed discontinuously throughout the sheet and forming fibrous areas or sections substantially free from re enerated cellulose, most of the fibers in t 1e unimpreg nated areas or sectionbeing anchored by contiguous portions of the regenerated cellulose. The reenforcing material extends in all -directions and cements or ties the sheets together into a unit.

Although I have referred to regenerated cellulose obtained from cellulose esters, such as viscose, I may also use as asource of such regenerated cellulose, cellulose dissolved directly in a reagent as in caustic soda at temperatures below C., cuprammonium, sul: phocyanides, and strong mineral acids. I, therefore, include in the term regenerated cellulose cellulose recovered or regenerated not only from its esters but also from solutions. I -designate Acellulose whether in the form of an ester or dissolved in caustic soda or rendered soluble by some other reagent as soluble cellulose.

My invention relates to a method and product resulting from the application of a soluble cellulose made prior to its application to the fibers as distinguished from cellulose dissolved in situ as would be the case if strong zinc chloride', caustic soda or sulphuric acid were applied to the untreated fibers in'discontinuous areas. I have called soluble cellulose appliedlby my method as added cellulose.

The invention is not limited to the process above described for addingV a cellulose-V yielding cement to the fibers. It is not necesi sary to produce a regular relation of the cementing areas, as exemplified by lines and dots-mechanically applied, for it is conteniplated that a spray, controlled in character and in proportion to fiber, be applied to felted fibers or to individual fibers or groups of fibers to be felted or in process of being f`elt-y ed, so that contacting fractions of fibers, or a fractional portion of the fibers are cemented together in the finished product, leaving a substantial area of the untreated fiber.

It will be noted that whatever method is employed, the she."L or mass which results is supportedby a continuous network of cellulose which comprises a fraction of the fiber cemented intor a supporting structure by add.- ed regenerated cellulose without weakening any fiber entering the network. i

Various other modifications of the process and of the product are contemplated as falling within the scope of the invention as deined by the appended claims. I claim:

1. A reenforced water-absorbent sheet of unwoven fibers, the reenforcing material comprisino added regenerated celluloseA distributed t 'scontinuously throughout said sheet terial comprising added regenerated cellulose distributed discontinuously throughout said sheet forming fibrous areas substantially free from said regenerated cellulose, most of the fibers in said areas being anchored by contiguous portions of said regenerated cellulose. 3. A reenforced Water-absorbent sheet of unwoven cellulosic fibers, the reenforcing material comprising added cellulose regenerated from viscose distributed discontinuously throughout said sheet forming fibrous areas isubstantially free from said regenerated cellulose, most of the fibers in said areas being anchored by contiguous portions of said regenerated cellulose.

4. A reenforced Watereabsorbent sheet of unwoven cellulosic fibers, the reenforcing material comprising added regenerated cellulose distributed discontinuously throughout said sheet forming fibrous areas substantiallyfree from said regenerated cellulose, the maximum dimensionof said areas being at most equal to the average length of said fibers.

5. A reenforced Water-absorbent sheet of long-fibered wood pulp, the reenforcing mateA rial comprising added regenerated cellulose distributed discontinuously throughout said sheet forming pulp areas substantially free "from said regenerated cellulose, most of the pulp fibers in said areas being anchored by contiguous port-ions of said regenerated cellulose.

6. A reenforced Water-absorbent sheet of mercerized long-fibered wood pulp, the reenorcing material comprising added cellulose regenerated from viscose distributed discontinuously throughout said sheet forming pulp areas substantially free from said'regenerated cellulose, most of the pulp fibers in said areas being anchored by contiguous portions of said regenerated cellulose.

Aeo

7. A reenforced water-absorbent sheet of unwoven cellulosic fibers comprising a multiplicity of closely packed thin sheets of said fibers cemented together by discontinuous reenforcing material, the reenforcing material comprising added regenerated'cellulose distributed discontinuously throughout said sheet forming fibrous areas substantially free from said regenerated cellulose, most of the fibers in said areas being anchored by con* tiguous portions of said regenerated cellulose. v

8. A` reenforced Water-absorbent sheet of long-fibered Wood pulp comprising a multiplioity of closely packed thin sheets of said pulp cemented together by discontinuous reenforcing material, the reenforcing material Adistributed discontinuously throu hout said sheet forming fibrous 'areas' su stantially free from said regenerated cellulose, the maximum dimensions of said areas being at most equal to the average length of said fibers,

said sheet bein impregnated with a small amount of emol ient.

10. The method for producing a reenforced water-absorbent 'sheet of unwoven fibers which comprises .impregnating a sheet of unwoven fibers with a discontinuous film of added soluble celluloseto'leave fibrous 'areas substantially free from said soluble cellulose and anchor most of the fibers in said areas by. contiguous portions of said soluble cellulose, and regenerating the cellulose from said solution.

l1.` The method for producing a reenforced water-absorbent sheet of unwoven fibers which comprises iinpregnating a sheet of Wood pulp witha discontinuous film of an added cellulose ester to leave pulp areas substantially free from said cellulosev ester and anchor most of the pulp fibers in said -areas vby contiguous portions of said cellulose ester, and regenerating the cellulose'from'said ester.

l2. The method for producing a reenforced Water-absorbent sheet of unwoven, fibers which comprises applying viscous solution of cellulose in" a discontinuous film to a 'sheet of Wood pulp to leave pulp areas subioc stantially free from said cellulose solution i and anchor most ofjthe'pulp fibers in said areas by contiguous portions of said cellulose solution, applying a similar discontinuous film to the opposite side of said sheet, and regenerating the cellulose from said solution.

13. The method for producing a reenforced water-absorbent sheet of unwoven fib-f.

ers from a plurality of sheets of said un- Woven fibers, which comprises applying viscous solution of a cellulose ester in a discontinuous film to a sheet of Wood pulp to leave pulp areas substantially free from said cel-` lulose ester, immediately applying a second sheet of said Wood pulp to the coated surface of said first sheet and applying pressure to unite the two sheets, the distribution of the cellulose ester in said compound sheet being such that most of the pul fibers in the unimpregnated areas are anc iored to contiguous portions of said cellulose ester, and

regenerating the cellulose from said ester.

14. ,The method for producing a reenforced" 13 water-absorbent sheet of unwoven bers from a plurality of sheets of said unwoven bers, which comprises applying viscous solution of viscose in a discontinuous film to a sheet of Wood pulp to leave pulp areas substantially free from said viscose, immediately applying a second sheet of said wood pulp to the coated surface of 'said rst sheet and applying pressure to unitethe two sheets, applying a discontinuous lm of viscose to the two exposed surfaces of said compound sheet, the distribution of the viscose in said compound sheet being such that most of the pulp bers in the unimpregnated areas are anchored to contiguous portions of said viscose, and re-y generating the cellulose from said Viscose.

l5. The method for producing a reenorced water-absorbent sheet of `unwoven bers which comprises impregnating a sheet of unwoven cellulosic bers with a discontinuous film of an added cellulose solution to leave brous areas substantially free from said cellulose solution and anchory most of the bers in said areas by contiguous portions of said cellulose solution, regenerating the cellulose from said solution, washin said sheet and drying said sheet under slig t tension.

16. The method for producing a reenforced water-absorbent Ysheet of unwoven bers which comprises impregnating a sheet 'of unwoven cellulosic bers with a discontinuous film of an added cellulose ester to leave fibrous areas substantially free from said cellulose ester and anchor most of the bers in said areas by contiguous portions of said cellulose ester, regenerating the cellulose from said ester, washing said sheet, introducing an emollient into said sheet and drying said emollient-containing sheet. l

17. The method for producing a reenforced water-absorbent sheet of unwoven bers which comprises applyin viscous solution of a cellulose ester in para el lines to one surface of the ber sheet, applying said viscous solution of cellulose ester to the opposite sur.

face of said sheet in similar, parallel lines but substantially at right angles to said first f said'ester.

lines,

coated bers; in the contiguous cellulose ester lines,

18.l -A brous Y sorbent cellulose fibers, vfra'otionalpertions of individual bers being .cemented together by added regenerated cellulose into asupport' said parallel lines being spaced at a* distance apart which anchors most .of the unsheet comprising Water-ab-l tional portion of the total mass of bers, to

leave substantial uncemented areas, most of the bers in said areas being anchored in said regenerated cellulose.

21. Fibrous cellulosic material in an a gregate of fibers having portions of sing e fibers cemented to portions of other single bers by added cellulose regenerated in situ,l

from viscose, whereby to unite the aggregate into a cemented whole.

'In testimony whereof, I have subscribed my name.

` MILTON SHOEMAKER.

ico

-nd'regenerating the cellulose from ing net-work to leave uncernented substantial portions of said cemented bers.

19. A fibrous sheet comprising water-absorbent .cellulose fibers reenforced by a network of cellulose, said network comprising contiguous bers cemented together b added regenerated cellulose, said cemente bers comprising a fractional portion of thev total mass of bers to leave substantial uncelas

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