US2319834A - Process for treating textiles - Google Patents

Description

Patented May 25, 1943 PROCESS FOR TREATING TEXTILES Roger N. Wallaclt, Briarcliff Manor, N. Y., assignor to Sylvania Industrial Corporation, Frederieksburg, "a" a corporation of V g a No Drawing. Application December 22, 1939, Serial No. 310,539

9 Claims. (01. 26-185) The invention relates in general to textiles and, in particular, to a method for stabilizing the structure and form of fabrics and to the stabilized textiles produced, and includes correlated improvements designed to enhance the characteristics and uses of such textiles.

In the conventional method of knitting and weaving fabrics, the yarns are subjected to ten sion. This is done to secure proper operation of the knitting and weaving machines and to secure uniformity in the finished product. The fibres and yarns constituting the fabric in its unfinished state (i. e., in greige goods) are in a condition of stress or stretch, and hence tend to shrink under any circumstances that permit or facilitate movement and contraction of the fibres.

Fabrics made in such a manner exhibit the tendency to shrink when subjected to wet treatment such as may be encountered in finishing operations. However, by the conventional methods of handling fabrics, part or all of the shrinkage so acquired may be offset or lost through mechanical strain and stretch that the fabric encounters in passing through these operations. Consequently, when the goods are again wet out, as in laundering, they will again exhibit the tendency to shrink either in the warp direction or filling direction or both, dependent on the degree of stretch present after finishing. The tendency to shrink will continue until the stretched condition of both the warp and filling threads has been relieved or until a balanced state of weaving contraction is obtained.

It has been proposed to provide a method of treatment that will shrink the fabric in both directions in a manner analogous to the shrinkage otherwise occurring in the laundering, washing or other cleaning process. This method is predicated upon the determination that the causes of shrinkage in a fabric subjected to full laundry treatment are mostly mechanical in effect. The process is, therefore, adapted to mechanically rearrange the fibres and to alter the crimp in the yarns of the fabric to the same extent that these fibres would rearrange themselves and the yarns be crimped if subjected to full laundry washing.

Basically, this process comprises the steps of determining the change in dimension that will take place in the fabric when it is subjected to washing, then mechanically shrinking the fabric down to-the dimensions so indicated, and finally completing the finishing operation without disturbing these dimensions. However, the prior methods of mechanical shrinking, such as the Sanforizing process, are forced to effect in a single treatment a complete shrinkage equal to the ultimate shrinkage obtained by repeated laundering or else the fabric will show an excessive residual shrinkage. This has many disadvantages for when a lot of goods are finished and come up to the Sanforizing machine, first a standard wash test is made and if same calls for 34 inch Sanforized width there is nothing the finisher can then do, although the converter may have specified 35 inch width.

Moreover, prior methods of shrinking fabrics have never been entirely successful when the fabric has been composed in whole or in part of artificial fibres, in particular of cut staple rayon. Owing to the swelling and shrinking which artificial filaments undergo on being wetted and dried, fabrics made of such filaments do not retain the condition produced by the preshrinking operation. However, even with fabrics made of natural fibres, such as cotton, the prior methods of preshrinking have not given results which were entirely permanent.

Furthermore, the stresses which fabrics undergo during wear and laundering frequently produce objectionable distortions even though such fabrics have been preshrunk by prior methods. Therefore, it is desirable to provide fabrics which are characterized by having a substantial permanent resistance to distortions of all types in order to preserve a desired structure, form and character in the textiles.

On the other hand, it is frequently desired to impart to fabrics a predetermined structure or shape designed to enhance its general utility or to render the textile adapted for some special uses. For example, it is desirable to provide a fabric having a predetermined and definite residual shrinkage so that the fabric will main tain its shape and structure during wear and laundering.

Accordingly, it is a general object of the present invention to provide a stabilized textile having a predetermined structure which is permanent.

It is another object to provide a method for setting and fixing the dimensions of fabrics in a predetermined manner.

It is a further object to provide a method for fixing a predetermined structure, stretch and/or shrinkage in fabrics.

It is a specific object to provide a method for establishing a permanent and predetermined residual shrinkage in textiles.

It is a further specific object to preshrink fab.

rics comprising artificial filaments, in particular, cut staple rayon, and to render the shrunk condition substantially permanent.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

According to the present invention, a fabric containing potentialy adhesive fibres is subjected to a shrinking operation and the shrunk structure fixed and rendered permanent by effecting adhosion between fibres in the fabric. The fibre adhesion is effected by rendering the potentially adhesive fibres tacky by treatment with a suitable solvent for such fibres before, during or after the shrinking operation and then rendering the adhesive material non-tacky while the fabric is maintained in the shrunken condition.

In the now preferred practice of the invention, the permanently preshrunk fabrics are made by mixing together, before the completion of the spinning, textile fibres and at least one type of fibres adapted to be rendered tacky by means of a solvent, and forming the mixture of fibres into a singles yarn, mechanically shrinking the fabric made therefrom, and fixing the shrunk structure by rendering the fibres tacky by treatment with a solvent therefore to effect a substantially permanent adhesion of fibres in the fabric while the fabric is maintained in said shrunken condition. The singles yarn may be prepared from the fibre mixture in accordance with the process disclosed in the co-pending U. S. application Serial No. 201,851, filed April 13, 1938, now Patent No. 2,252,999. The shrinkage of the fabric may be partial or complete or to any predetermined amount, and may be efiected on woven, knitted, netted or other fabrics in one or more dimensions. The expression shrinking is intended to include all changes in the fibre size, length and crimp and changes in yarn length, crimp and displacement in fabrics, which produce a decrease in dimension or a contraction in the fabric.

For the non-adhesive textile fibre there may be used any suitable natural or synthetic fibres of textile-making length, for example cotton, fiax, jute, and other vegetable fibres; wool, hair, silk, and other animal fibres; asbestos, glass, mineral wool, and other mineral fibres; also artificial fibres or filaments formed of cellulose compounds, such as regenerated cellulose or cellulose hydrate of all kinds, cellulose derivatives, such as the esters, the ethers, whether soluble in water, alkali or organic solvents, mixed cellulose esterethers, hydroxy-alkyl and carboxy-alkyl ethers of cellulose and xanthates of the cellulose ethers, cellulose thiourethanes, cellulose xantho-fatty acids and fibres formed from natural or synthetic resins of all kinds, all of which fibres are so selected that they will not be rendered tacky under the conditions which are employed to render the potentially adhesive fibres tacky.

The potentially adhesive fibre may comprise any of the fibres described above which can be rendered adhesive by suitable treatment with a suitable solvent as hereinafter described, but in the now preferred embodiment the potentially adhesive fibre is a synthetic resinous material or a non-fibrous cellulosic material, capable of being formed into fibres which have an inherent tackiness upon treatment with a suitable solvent, for example, as the resins formed by the polymerization of various organic compounds such as cumarone, indene hydrocarbons, vinyl, styrene, sterol aldehyde, furfural ketone, urea, thiourea. phenol-aldehyde resins, either alone or modified for example, as copolymers of vinyl halide and vinyl acetate, co-polymers of vinyl halide and an acrylic acid derivative, co-polymers of vinyl compound and styrol compound; and also fibres formed from a mixture of resins, such for example as a mixture of vinyl resins and acrylic acid resins or methacrylate resins, a mixture of polyolefine resins and phenolaldehyde resins, or a.

mixture of two or more resins from the different classesjust named.

In addition to the synthetic resins, there may be employed for the potentially adhesive fibre, a fibre formed from a thermoplastic cellulose derivative, such for example as a cellulose ester, a cellulose ether, a mixed cellulose ester-ether, a mixed cellulose ether, a hydroxy-alkyl or carboxy-alkyl ether of cellulose, a cellulose ether xanthate, or a cellulose thiourethane. In particular, the thermoplastic cellulose derivative fibre may be a fibre of cellulose acetate, cellulose nitrate or an organic soluble cellulose ethyl ether, and the like; also fibres formed from a mixture of cellulose derivatives and resins, such for example as a fibre formed by extruding a mixture of cellulose nitrate and an oil soluble phenolaldehyde resin, or a cellulose acetate and an acrylic acid resin, or an organic soluble cellulose ether and a vinyl resin; also fibres formed from resins such as those formed from polybasic acids and aliphatic diamines (nylon type), either unstretched or pre-stretched; and fibres formed from a natural or synthetic rubber and rubber derivatives.

For the thermoplastic potentially adhesive fibre, it is preferred to employ a resin fibre because such fibres, as compared to the cellulose derivative fibres, are tougher and harder, become tacky at lower temperatures and cool to form tough or pliable products. Moreover, the resin fibres are inert to acids, alkalies and dry cleaning fluids, and are not water swelling. This latter property prevents distortion of the adhesive bond, tends to stabilize the twist and shrinkage of the fabric, and the adhesive is more permanent so that the wet and dry tensile strength of the adhesive bond will be substantially the same. Finally, the resin fibres exhibit, particularly when plasticized, a high tensile and a true elasticity, practically as great as that of natural silk.

The non-adhesive textile fibres and/or the potentially adhesive fibres may be prestretched fibres or filaments. In such cases the shrinking treatment advantageously includes treatment wit a suitable chemical reagent or heat to effect a s kage of the prestretched fibre. The resulting fibre-shortening will produce yarn shrinkage and augment the decrease in fabric dimension.

The articles of the invention are fabricated from yarns comprising at least two dissimilar types of fibres at least one of which type is potentially adhesive.

The mixing of the dissimilar fibres may be carried out in a suitable manner such, for example, as by blending at least two types of fibres before and/or during carding, combing, drafting, but before completion of the spinning of the fibres into a singles yarn. Thus the two types of fibres may be mixed and fed'together into a carding machine; or slivers are made from each type independently and the slivers combined by drafting and spinning into a yarn. Alternately, a yarn containing the potentially adhesive fibres may be twisted or doubled with a yarn of similar type or with a yarn not containing potentially adhesive fibres. The invention is particularly adapted for permanently controlling or fixing a shrunk condition in a fabric comprising yarns made from non-adhesive and potentially adhesive fibres mixed together before the completion of the spinning of the yarn.

The relative proportions of the non-adhesive textile fibres and of the potentially adhesive fibres may be varied in aoordance with their properties, the nature of treatment, the intended use of the finished product and the characteristics desired therein. The mixture of fibres may be spun into yarns and threads and fabricated into fabrics in a known manner.

In its broad aspects the process of the invention is applicable for permanently fixing the structures and form of fabrics after they have been modified by shrinking. It is to be understood that the invention is not limited to any particular method or apparatus for carrying out the shrinking steps of the present process. Suitable means for carrying out the shrinking operations involved in the present invention are shown in U. S. Patents Nos. 1,982,720, 1,988,376, 2,021,975 and 2,052,948. By way of illustrating, but not by way of limiting the invention, the following methods may be employed for shrinking fabrics in accordance with the present invention.

1. Stretching a moistened fabric in one dimension while permitting or controlling the shrinkage in another dimension. In this embodiment a woven fabric is subjected to moisture and preferably a suitable activating agent and thereafter stretched in the direction of one of its constituent sets of yarns, either warn or weft, while leaving the other set free from tension or under a limited tension and drying the fabric while maintaining the tension on the one set of yarns. The stretching of the one set of yarns causes a contraction and increased crinkle or undulation of the yarns in the other set. The shrinking is carried out while the thermoplastic fibres are in a tacky condition and the adhesive material is rendered non-tacky while the one set of yarns is maintained under tension. The increased crinkle or shrunk structure is rendered substantially permanent by the adhesion of the fibres in the fabric. This method can be used for shrinking knitted fabrics in one dimension.

2. By moistening and stretching the moist fabric in one dimension while permitting or controlling the shrinkage of the fabric in the other dimension whereby the unstretched yarns acquire additional crinkle, drying the fabric while under tension, again moistening the fabric while free of tension to cause a swelling of the yarns and a. consequent shrinkage of the first stretched yarns, and again drying the fabric under pressure, but free of tension. In this embodiment the potentially adhesive fibres are preferably rendered tacky during or after the final drying step. By this method a. fabric can be permanently shrunk in two dimensions.

3. By moistening a fabric, mechanically compressing the moistened and preferably activated fabric in one dimension whereby the yarns acquire additional crinkle, maintaining the fabric under pressure while drying the fabric. The activation of the potentially adhesive fibres may take place before, during or after the drying step, and the deactivation of the fabric may take place after the drying by cooling while the fabric is maintained in the preshrunk condition. One embodiment of suitable means for carrying out the shrinking in this process is disclosed in U. S. Patent No. 1,861,422.

4. By moistening a fabric while maintaining one yarn system under tension and permitting or controlling the shrinkage of the other yarn system, that is, by permitting the other yarns to crinkle, thereafter mechanically compressing the yarn system previously maintained under tension to shrink that system by increasing the yarn crinkle or undulation. One embodiment of suitable means for carrying out the shrinking in this process if disclosed in U. S. Patent No. 1,861,423. The activation of the potentially adhesive fibres may be effected before, during or after the drying step and the deactivation of the fabric after the drying of the fabric.

In the mechanical shrinking treatments described above a chemical swelling agent may be employed in place of or in addition to water and such agent may be used to facilitate rendering the thermoplastic fibres tacky.

Textiles comprising prestretched fibres, whether they be the adhesive or the non-adhesive fibres, may be shrunk by treating the textile to cause the prestretched fibre to shrink as by treating the textile with a solvent or swelling agent of the prestretched fibre or by heating the textile in case the prestretched fibre is thermoplastic. Prestretched nylon or vinyon fibres are particularly.

adapted to be shrunk by heat.

The shrunk structure and form given the fabric by the shrinkage treatments just described may be rendered permanent and the textile stabilized by activating the potentially adhesive fibres to render them tacky by treatment with a suitable solvent before, during or after shrinking the fabric, and deactivating the fabric while in the shrunk condition and form to effect a substantially permanent adhesion between the fibres and to set the yarn relationships.

The activation of the potentially adhesive fibres takes place preferably before the shrinking operation occurs and the fabrics are subjected to the shrinking operations while these fibres are in a tacky condition. The deactivation of the adhesive or adhesive fibres takes place while the fabric is maintained in the shrunk condition. While the fibres are in an adhesive condition, the fabric preferably is subjected to a squeezing or compacting treatment to promote adhesion of the associated fibres at their points of contact as by passing the fabric between pressure rollers. The squeezing may be effected by the means employed for mechanically shrinking fabrics as described herein. If the fabric is to be shrunk in two dimensions, the deactivation of the adhesive or of the adhesive fibres preferably takes place after the completion of both shrinking operations while the fabric is in a relaxed state or under controlled tension. The shrunk structure should not be placed under distorting tensions during the deactivation treatment.

In the preferred embodiment the potentially adhesive .fibres may be rendered tacky by use of hot air, hot water or by contact with hot surfaces. with the addition of a solvent or plasticizer, and with or without the use of pressure. Deactivation may be accomplished by heating to a higher temperature, to evaporate the solvent.

A plasticizer advantageously may be applied to the fibres and/or to the fabric before the activation of the fibres. The plasticizer may function to increase the flexibility of the fibres and, when employed with thermoplastic fibres, the plasticizer may serve, in addition to modify the thermal softening point. After the textiles have been shrunk and deactivated the plasticizer may be allowed to remain in the textile or it may be removed by suitable means such as washing and extraction. The removal of the plasticizer will raise the temperature at which thermoplastic material in the textile will again be rendered soft and cementitious, thus adapting the textile for use at more elevated temperatures than would be the case if the plasticizer were present. The plasticizer may serve also as a shrinking agent or as a latent activating agent for the potentially adhesive fibres.

The properties of the finished product depend upon various factors, such as the nature and proportion of potentially adhesive fibres; the extent of the activation thereof; and the tacky condition of the fibres during squeezing or pressing and the nature of the deactivation and the extent of shrinking. The extent of activation may be varied considerably, depending upon the relative proportions ofv the types of fibres, the properties of the fibres, and the effect desired in the product.

The fibres may be rendered superficially adhesivc; or rendered plastic and tacky without losing their fibrous form; or made to lose their fibrous structure and form an adhesive. The tacky fibres will cohere to each other and adhere to the other fibres to fix the position thereof to give a product having increased tensile strength and lower stretch and shrinkage. If the activation is such as to form an adhesive, the adhesive will cause the other fibres to be permanently adhered and the shrunk structure permanently set.

While a knitted fabric has, of course, only one yarn system, it may be shrunk in a manner similar to a woven fabric by one or more of the methods just described which are appropriate therefor and the present invention is intended to include fixing the shrunk structure of both woven and knitted fabrics.

By way of illustrating, but not by way of limiting the invention, there will be given a specific example.

Example parts by weight of ethyl cellulose staple fibres of the organic-solvent-soluble type are admixed with 90 parts of cotton fibres of similar passes from the shrinking apparatus it is cooled thereby rendering the ethyl cellulose non-tacky and creating a permanent bond between the fibres in the fabric, thus stabilizing and rendering permanent the weaving contraction.

The effect of the combined shrinking and setting operations of the present invention may be illustrated by comparing the untreated with the treated fabric. In the untreated fabric the warp yarns and the weft yarns show only a slight undulation and the yarns are relatively distant from one another giving. the fabric a loose, porous appearance. When the fabric is shrunk in one dimention only, for example. by stretching the warp yarns of a pre-moistened fabric, while permitting or controlling the weft contraction, there is produced a product in which the warp yarns lie substantially fiat and in the same plane, while the weft yarns exhibit an increased crinkle and a decreased over-all length. If this fabric be subjected to warp-wise shrinkage as by mechanically compressing the warp yarns longitudinally by any suitable method, the warp yarns may be given an increased crinkle also, thus bringing the weft yarns closer to each other. In the final product, shrunk in both directions, both series of yarns have a substantial crinkle and the yarns lie relatively close together in contrast to the untreated fabric.

While the fabric is in the shrunk condition the deactivation of the previously activated adhesive fibres causes the component fibres of the yarn to adhere to each other. This adherence of the fibres renders permanent the crinkle imparted to the yarn by the shrinking operation and anchors the yarns to each other in their new relationship. The shrunk condition which is set by the deactivation need not be that condition produced by repeated launderings, but may be a shrunk condition intermediate between that of the untreated fabric and that of the ultimate shrinkage after laundering. This effect is not obtainable by the shrinking operation alone, but only by the use of the combination of the shrinking with the setting operation in accordance with the present invention.

Accordingly, the present invention provides, inter alia, that a fabric may be shrunk to a predetermined, but not necessarily the ultimate shrunk condition. and such shrunk condition rendered permanent so that the fabric neither shrinks nor expands to any substantial extent upon laundering, dry cleaning or wearing. Thus,

- the present invention provides a method for setdistribute the weaving contraction between the ting and fixing the dimensions of fabrics in a predetermined manner and for establishing a predetermined and residual shrinkage in textiles and these results may be obtained in fabrics made from artificial filaments. in particular, cut staple rayon, as well as in fabrics made from natural fibres.

Since certain changes in carrying out the above process, and certain modifications in the article which embody the invention may be made without departing from its scope, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

The process of stabilizing pre-shrunk fabrics broadly and the products so produced, as well as the specific method of rendering the potentially adhesive fibres tacky by heating are claimed in the co-pending application of Carleton 8. Francis, Jr., Serial No. 310,553 filed December 22, 1939,

Having described my invention, what'I claim as new and desire to secure by Letters Patent is:

l. A process of treating a fabric containing potentially adhesive fibres, comprising treating the fabric with a solvent which will render said potentially adhesive fibres tacky, shrinking said fabric while said fibres are in a tacky condition and fixing the shrunk structure by rendering the tac material non-tacky, to effect adhesion between the fibres in the fabric.

2. A process of treating a' fabric containing potentially adhesive fibres comprising treating the fabric with a solvent which will render said potentially adhesive fibres tacky, shrinking said fabric while the fibres are tacky to a condition less than that of ultimate laundry shrinkage, and fixing the shrunk structure by rendering the tacky material non-tacky, to effect adhesion between the fibres in the fabric. a

3. A process of treating a fabric containing potentially adhesive fibres comprising treating the fabric containing yams spun from a mixture of potentially adhesive fibres and textile fibres with a solvent which will render said potentially adhesive fibres tacky, shrinking said fabric and fixing the shrunk structure by rendering the tacky material non-tacky, to effect adhesion between the fibres in the fabric.

4. A process of treating a fabric containing potentially adhesive fibres comprising shrinking a fabric comprising potentially adhesive fibres and fixing the shrunk structure by treatment with a solvent to eifect adhesion between the fibres in the fabric and removing said solvent.

5. A process of treating a fabric containing potentially adhesive fibres comprising moistening the fabric with water, stretching the moistened fabric in one dimension while allowing shrinkage of the fabric in the other dimension, maintaining the'fabric in said stretched condition while activating the potentially adhesive fibres with a solvent to effect fibre adhesion in the fabric, and removing said solvent.

6. A process of treating a fabric containing potentially adhesive fibres comprising moistening the fabric with water, stretching the moistened fabric in one dimension while allowing shrinkage of the fabric in the other dimension, drying said fabric under tension, again moistening the fabric with water while the fabric is substantially free of tension to allow the unstretched yarns to swell and shorten thereby causing the stretched yarns to crinkle, activating the potentially adhesive fibres with a solvent to effect fibre adhesion in the fabric. and removing said solvent.

7. A process of treating a fabric containing potentially adhesive fibres comprising moistening the fabric with water, longitudinally shrinking one of the yarn components by compression exerted parallel with the surfaces of the fabric, maintaining the fabric in said compressed condition while activating the potentially adhesive fibres with a solvent to effect fibre adhesion in the fabric, and removing said solvent.

8. A process of treating a fabric containing potentially adhesive fibres comprising moistening the fabric with water, stretching one yarn component of the moistened fabric while allowing shrinkage of the fabric in the other yarn component, drying the fabric while in said stretched condition, longitudinally shrinking the previously stretched yarn component by compression, maintaining the fabric in said compressed condition while activating the potentially adhesive fibres with a solvent to effect fibre adhesion in the fabric, and removing said solvent.

9. A process of treating a fabric containing potentially adhesive fibres comprising treating the fabric with a non-solvent swelling agent, stretching the treated fabric in one dimension while permitting shrinkage of the fabric in the other dimension whereby the unstretched yarns acquire additional crinkle, drying the fabric while the stretched yarns are under tension, again treating the fabric with a non-solvent swelling agent while free of tension to cause a swelling of the yarns and a shrinkage of the previously stretched yarns. treating the fabric with a solvent for said potentially adhesive fibres to effect adhesion between fibres in the fabric and removing said solvent while the fabric is maintained under pressure.

ROGER N. WALLACE.