US3197790A

US3197790A - Process for imparting durable loft and warmth to cellulosic fabrics

Info

Publication number: US3197790A
Application number: US365486A
Authority: US
Inventors: Nelson F Getchell
Original assignee: COTTON PRODUCERS INST OF N
Current assignee: COTTON PRODUCERS INST OF N; COTTON PRODUCERS INSTITUTE OF NATIONAL COTTON COUNCIL OF AMERICA
Priority date: 1964-05-06
Filing date: 1964-05-06
Publication date: 1965-08-03
Anticipated expiration: 1982-08-03

Description

United States Patent 3 197 7 success non ruranhnsh Lori" ANB WARP rel Til FABRKCS Nelson l. Gete ll Gr at Falls, Va, assignor to (lotion Producers institute of The National Cotton Council of America, Memphis, Tenn, a corporation of Tennessee No Drawing. Qontinuation of application Ser. No.

13%,330, Mar. 16, E62, application May 6,

Ser. No. 365,436

4 Claims. (Cl. EZ1?.6)

This application is a continuation of my application Serial No. 180,330, filed March 16, 1962, now abandoned.

The present invention relates to a process for imparting desirable characteristics to cellulosic materials and, more particularly, to a process for treating lofty cellulosic materials whereby the loft of the cellulosic material is retained even after repeated launderings and extended periods of use.

It is well known that the insulating value of a fabric, and therefore its warmth, depends upon the immobilized or dead air entrapped in the interstices between the fibers and between the yarns, rather than upon the insulating characteristics of the individual fibers of the fabric. Hence, the warmth of a fabric may be described as being a function of its thickness, or loft, and the insulating properties of the fabric are excellent when the ratio of the volume of entrapped air to the fibers of the fabric is large.

While it has been possible to produce lofty cellulosic materials, such as cellulosic fabrics, suitable for use in winter weight clothing, blankets, and the like, and these articles have initially had good warmth characteristics and a good appearance, they have had the principal disadvantage that after a period of use and/or after repeated launderings, the lofty characteristic of the material is substantially decreased, due to the matting of the fibers. Once the cellulosic fibers of the fabric become compressed, the fabric cannot recover its previous lofty condition due to the poor resiliency of the fibers. The cellulosic fabric not only loses its original lofty appearance but also loses its softness and a substantial portion of its insulating or warmth properties. Even though cotton fibers, per se, are durable in that they can undergo unlimited and repeated launderings and can withstand harsh treatment, cellulosic materials, such as cotton fabrics, are not as widely used as they could be in the making of winter weight garments, such as sweaters, suits, jackets, and the like, because of the aforesaid disadvantages resultin from the inability of the material to retain its lofty appearance.

While cotton is abundant in this country and is less expensive than other fibers, both natural and synthetic, it has been unable to compete commercially with these other fibers in those areas where a durable loft is a principal prerequisite of the finished article.

The field of winter weight fabrics represents a very large potential market to the cotton industry. This market has been dominated by wool for many years, but during the last several years the manufacturers of synthetic fibers and fabrics have been making spectacular gains through the use of their bulk or textured yarns. Fabrics made from this new type of synthetic yarns or blends of wool and synthetic fibers have become increasingly popular for such uses as mens, womens, and childrens sweaters, coats, suits, and other outerwear garments. The successful development of cotton fabrics having the desired esthetic and physical properties would significantly improve cottons competitive position in the field of winter weight fabrics.

Accordingly, it is an object of this invention to obviate the above disadvantages which are present with respect to maintaining a durable loft on cellulosic materials.

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Another object of this invention is to provide a process for treating cellulosic materials whereby the loft of the material is retained even after the material has been subjected to repeated laundering operations.

It is another object of this invention to provide lofty cellulosic materials, including cotton textile fabrics, which are well-suited for use in making warm, insulating winter weight garments, blankets, and the like, and which have the ability to retain their loft and appearance, and thus their insulating characteristics, even after being laundered repeatedly.

in attaining the objects of this invention, one feature resides in subjecting the cellulosic material to a bath containing a crosslinking agent capable of reacting with the cellulosic fibers of the material, extracting the excess of the agent, drying the material and, prior to reacting the agent with the cellulosic material, subjecting the dry cellulosic material to a mechanical action, such as tumbling, brushing, iluffing, or the like, whereby the material is lofted and maintained in this lofty condition while the material is subjected to the conditions necessary to cause the reaction between the cross-linking agent and the cellulose to be completed.

Another feature resides in mechanically agitating the treated cellulosic material while simultaneously drying the material in order to restore the lofty condition to the material, and then subjecting the treated material to the conditions necessary to effect a cross-linking between the reagent and the cellulosic fibers.

A further feature resides in imparting a loft to a cellulosic material and, while maintaining the lofty condition of the material, applying thereto an amount of a cross-linking reagent at least suiiicient to set the fibers in their lofty condition, and reacting the reagent with the cellulosic material to set the fibers.

Other objects, features, and advantages will be apparent from the following description of the invention.

It has been discovered that the objects set forth above, as well as others, can be obtained by first treating the cellulosic textile materials with any of the many different reagents presently used to enhance the crease resistance of cellulosic textiles and/ or to give wash-and-wear characteristics thereto, and, prior to reacting the reagent on the material, bringing the cellulosic material to its lofty condition and setting the material in this condition during the curing stage of the reagent. The cellulosic material, which may be a cotton textile, including a woven or non-woven fabric, or the lik then retains its loft through repeated launderings and fabric deformations.

More specifically, lofty cotton textile fabrics are first treated with either a solution, suspension, dispersion, or a paste of an organic cross-linking reagent which is applied to the fabrics by any conventional method such as dipping, spraying, brushing, immersion, padding, coating, or the like. The excess reagent is then removed from the cellulosic material by any known means, such as by squeezing between rollers, by passing over vacuum slots, or by centrifuging, and the like. The fabric which now has its fibers in a compressed or matted condition, is mechanically worked until its lofty condition is restored; i.e., there is an increase in the thickness of the fabric and an increase in the ratio of the volume of entrapped air to the volume of the cotton fibers. This mechanical working is carried out by either tumbling, brushing, or flufiing the fabric, or by other procedures which accomplish the same effect, while the fabric is being simultaneously dried at a relatively low temperature to remove unwanted moisture. Alternatively, the drying may be carried out before the treated fabric is subjected to the aforesaid lofting step.

Following thes subjected to the e operations, the treated lofty fabric is particular conditions necessary to cure the reagent. This may be accomplished by the use of high temperatures, or by the presence of alkaline or acidic conditions, or by the action of other factors, depending upon the reagent used, thereby setting the fabric in its lofty configuration. As a result of this process of lofting by the present invention, the fabric returns to its lofty configuration after repeated washings and deformations. Fabrics not subjected to the letting operating become matted and compressed and their surfaces may become disarrayed and less attractive after repeated launderings.

For purposes of this invention, the reagents which are used in treating the lofty cellulosic material and which are cured thereon to set the materials in their lofty condition are identical to those which have been used by the cotton industry for imparting crease-proofing and/ or wash and wear characteristics to cellulosic materials. These reagents will be referred to as cross-linking reagents in this specification and claims, even though the art is not certain that these reagents actually cross-link the cellulosic molecules of the fibers. stricted to any theory as to why the results are achieved, since the fact remains that they are achieved. Thus, the term cross-linking reagents is to be understood to include the group of chemicals which are known or recognized by the art to impart crease-proofing and wash and wear properties to cellulosic fabrics.

Among the various and well known cross-linking reagents which may be used in the process of this invention are the aldehydes, such as formaldehyde; polyacetals, which are the products of a reaction between aldehydes and polyalcohols; methylol urea precondensates, such as dimethylol urea; cyclic methylol urea compounds, such as dimethylol ethylene urea, i.e. 1,3-bis-(hydroxymethyl)-2- imidazolidone; triazones such as 1,3-dimethylol-5-hydroxy ethylperhydrotriazone-2; methylol melamine compounds and triazines, such as are produced by reacting melamine with formaldehyde; epoxides and related compounds, such as diglycidyl ether of ethylene glycol; and tris-l-aziridinyl phosphine oxide which imparts both crease and flame resistance to the cellulose; dichloropropanol; and ethyl carbamate.

Also included as cross-linking agents within the meaning of this term for the present invention, are condensatlon products of formaldehyde with acetone, with acrolein, with acetone and acrolein, with phenol, with diethylene glycol dicarbamate, with formamide, with hydroxyl amines, with polymerized methacryl amides, with urea and alkylene oxides and epichlorohydrin, with tetrahydroimmopyrimidine, with hydrazines of monoand dicarboxylic acids, with low-molecular weight polyesters or polyurethane, with nitrilotripropionam-ide, with glyoxal and urea, with hexamethylene diamine and urea, with hexose ureides, with dicyandiamide and urea, and with 2-oxo-4,5-diimino parabanic acid resins; the urons; chloromethyl ethers of polyhydric alcohols; dicarboxylic acid anhydrides and diesters; copolymers of ethylenic di-carboxylic acids with vinyl compounds; salts of poly (vinyloxyalkyl) amines; cyclopropyl quaternary ammonium compounds; silicones and resin precondensates; quaternary ammonium derivatives of silicones, and halo-silanes; bis- (hydroxymethylurethane) of 1,4-butanediol; orthophosphoric acid, urea, and sodium hydroxide; diisocyanates; aldehyde-ethylene imine reaction products and phosgeneethylene imine reaction products; formyl alkyl oxetanes; divinyl sulfone, its derivatives, and vinyl sulfone-urea addition products; onium compounds; and rubber latex with chloromethyl ethers. Mixtures of any of the above may also be used.

While all of the above cross-linking reagents are known to produce the desired results on cellulosic fabrics, among the ones which are used commercially by the cotton industry to impart the desired creaseproofing or wash and wear properties are included cyclic ethylene urea, 1,3- dimethylol-S-hydroXyethyl-perhydrotriazone-2, diglycidyl ether of ethylene glycol, tris-l-aziridinyl phosphine oxide Applicant does not want to be re- 4 and divinyl sulfone or divinyl sulfone donors, i.e., compounds which. form divinyl sulfone during the treatment of the fabric. Also included are the melamine formaldehyde precondensates.

Some of the above-listed cross-linking reagents require the presence of catalysts during the curing step, while others, such as trimethylol phenol, do not. The f0rmaldehyde resins usually require acidic catalysts, while others, such as divinyl sulfone, require alkaline catalysts. Hence, whether a catalyst is used and whether it is acidic or basic will depend upon the particular cross-linking reagent used. Generallthe catalysts belong to the following groups: organic acids, such as maleic, acetic, tartaric, oxalic, lactic, etc.; inorganic acids, such as hydrochloric; metal salts, such as aluminum, magnesium, copper, zinc, and calcium ch10;

rides, zinc nitrate, zinc fiuoroborate and the like; ammonium salts, such as ammonium chloride, ammonium phosphate, ammonium sulfate, etc; organic amine salts such as the hydrochloride salts; alkali hydroxides and carbonates; as well as many others which will readily come to mind, depending upon the particular cross-linking reagent to be used.

In the same manner, the temperature of the curing step, the length of time for the cure, etc., will depend on the reagent-catalyst system employed, and the weight and type of fabric being treated. These are matters which are well known to those skilled in the art.

The amount of cross-linking reagent which is deposited on the cellulosic textile will usually vary from about 1 to about 15% by weight of the cellulosic textile. Amounts larger than 15% by weight may be used, if desired, but generally there is no additional advantage to be gained thereby. In fact, some beneficial results are obtained even when the amount of cured reagent on the fabric is less than 1% by weight of the fabric.

The solution, dispersion, or emulsion preferably used for immersion of the cellulosic material is an aqueous one as a matter of convenience and availability, since most commercial cellulose textile processors prefer to use aqueous systems rather than the more costly non-aqueous systems. Any suitable solvent may be used, however, depending upon which system is to be utilized. Wetting agents may also be present in the treating bath along with softeners, lubricants, stiffening agents, and the hand modifiers, as well as other conventional finishing agents.

In the following examples, which are only illustrative of the invention and are not to be considered as limiting the invention in any way, various cellulosic textiles were subjected to the process of the invention, and the appearance of the pile and the feel of the treated textiles were evaluated. The thickness and compressibility were measured with a compressometer as described by H. F. Scheifer, J. Res. Nat, Bureau of Standards 10, 705 (1933), RB. 561; and the compressibility was evaluated as follows:

z p essibility, p r llti where t is the thickness at the pressures indicated.

Example I A treating solution was prepared which contained 24.5% dimethylol ethyl triazone having the formula nornonriiawomon and 2.9% maleic acid as a catalyst therefor, the remaindor being water. Samples of a commercial cotton blanket were immersed in this solution and padded to wet pickups of approximately of fabric weight. The samples were then tumbled in a tumble dryer without heat for 15 minutes, then tentered, and lightly brushed. They were then dried at 220 F. until dry to the touch, and then cured for 2 minutes at 320 F. The dry add-on after curing was approximately 12.5 The samples were given a light scour to remove residual reagents. Their thickness was superior to and the appearance of their pile similar to that of the original samples.

Example 11 Treatment of the sample was exactly like that described under Example 1 except that the brushing of the pile was omitted. Gn a subjective rating scale on which the appearance of the original pile rated and on which a very disturbed, unsightly pile rated 0, the pile of the treated sample was rated 8 after the scour. *lowever, after 10 typical laundering cycles in an automatic home washing machine, the appearance of the treated sample was superior, being rated 5 while that of the untreated sample was rated 1. The thickness of the treated sample after the process wash was 116 mils, and its compressibility 41%; the corresponding figures for the original sample were 80 mils, and 31%; these results indicate the better loftiness of the treated sample.

Example 111 The treatment of the sample was like that described under Example ll except that the concentration of the triazone was 13.4%, and that of the maleic acid catalyst was 1.6%. This resulted in a slightly lower thickness and poorer retention of the pile appearance. Thus, the thickness after scouring was 109 mils, the compressibility 44%, and the rating of the pile appearance after 10 launderings was 3.

Example IV This treatment was like that described under Example IV except that the dimethylolethylene urea concentration was 11%, and the zinc nitrate concentration 1%. This resulted in improvement of the thickness and compressibility similar to that in Example IV but in better retention of the pile appearance in laundrering. Thus, the thickness after the scouring was 121 mils, the compressibility 40%, and the rating of the pile appearance after 10 launderings was 6.

Example Vl This treatment was like that described under Example V except that 1% (based on fabric weight) of a polyeth lene softener was added to the bath. This resulted in a softer hand but somewhat lower thickness of the sample, and poorer retention of the appearance of the pile. Thus, the thickness after scouring was 98 mils, the compressibility 44%, and the pile appearance rating after 10 launderings was 5 Example VII This treatment was like that described under Example V except that the sample was padded through a 1% (based on fabric weight) solution of polyethylene softener after curing, and dried at 220 F. This resulted in a softness of the sample similar to that obtained in Example VI, in a thickness between that obtained in Examples V and VI, and in somewhat better retention of the pile appearance in repeated laundering than in Examples V and VI. Thus,

after scouring the thickness was 113 mils, the compressibility 41%, and the pile appearance rating after 10 launderings was 7.

6 Example- VIII The treatment was like that described under Example V except that 2% polyvinyl acetate was added to the bath. This resulted in a somewhat harsher, scoopier hand or feel than that in Example V, but relatively little change in loft and pile appearance. The thickness of the sample after scouring was 113 mils, the compressibility 39%, and the pile appearance rating after 10 launderings was 5.

The presence of a harsher, scroopier hand or feel in the cotton textile, such as achieved by the process of Example VIII, may be desirable in many instances, particularly with respect to cotton blankets and certain winter wear garments. Modified urea-formaldehyde polymers, or other known hand stiffeners, may be used in place of the polyvinyl acetate of Example VIII, for achieving substantially the same results.

The principle of the present invention is applicable to cellulosic materials including fibers, filaments, yarns, textile fabrics including woven and non-woven textiles and fabrics, and the like, as well as materials formed from blends of cellulosic fibers with other fibers, whether natural or synthetic, which cellulosic materials either have a lofty configuration or can be so treated as to impart thereto a lofty configuration. When treated with the process of this invention, such cellulosic materials retain this lofty configuration even after repeated launderings or deformations. Included in the term cellulosic are cotton, rayon, and linen materials, and this term is not to be restrictive in any manner. Ramie, hemp, jute, and the like are other examples of cellulosic materials.

While the invention is primarily concerned with'the retention of the loft of the cellulosic material, the principles of the invention are also applicable to those cotton fabrics which as manufactured have no loft originally but which have the capacity to be lofted, if desired, such as some loosely woven materials coming directly from a loom. Such materials can be lofted by mechanical action as described in this application and then treated with the cross-linking reagents in accordance with the invention, so as to retain the loft.

Furthermore, cellulosic materials including napped fabrics, pile fabrics, tweed, and other winter weight cellulosic materials which are in a lofty condition can be treated so as to retain the lofty appearance even after launderings, deformations, and the like, by subjecting the materials while in their lofty condition to a fine mist or a vapor of the cross-linking reagent for a period of time sufficient to deposit the necessary amount of the reagent on the material and then curring the deposited reagent, care being taken to maintain the loft of the material during the deposition and curing phases.

Other modifications will be apparent to those skilled in the art without departing from the scope and spirit of this invention. Therefore, the claims which appear below should be construed as encompassing all the features of patentable novelty which reside in the present invention including all features which would be treated as equivalents thereof by those skilled in the art to which the invention pertains.

Iclaim:

E. A process for imparting to a cellulosic fabric the desirable characteristic of maintaining its appearance even after repeated launderings and for increasing its thickness, compressibility, and insulating properties, comprising applying to said cellulosic fabric a crosslinking reagent capable of reacting with the cellulosic molecules or" said fabric and forming crosslinkages with said molecules, lofting the fabric by mechanical agitation to increase the thickness of the fabric and increase the ratio of the volume of entrapped air to the volume of cellulosic fibers and then curing the crosslinking reagent on said lofted fabric while said fabric has an increased thickness and has the volume of entrapped air to the volume of cellulosic fibers increased.

2. The process as defined in claim 1 wherein said cellulosic fabric is a winter Weight fabric.

3. A process for imparting to a mapped, Woven cellulosic fabric the desirable characteristic of maintaining its napped appearance even after repeated launderings and for increasing its thickness, compressibility and insulating properties, comprising applying to said cellulosic fabric a crosslinking reagent capable of reacting with the cellulosic molecules of said fabric and forming crosslinkages with said molecules, lofting the fabric by mechanical agitation to increase the thickness of the fabric and increase the ratio of the volume of entrapped air to the volume of cellulosic fibers and then curing the crosslinking reagent on said lofted fabric While said material has an increased thickness and has the volume of en trapped air to the volume of cellulosic fibers increased.

4. A process for imparting to a mapped, woven cellulosic blanket the desirable characteristic of maintaining its napped appearance even after repeated launderings and for increasing its thickness and compressibility and insulating properties comprising applying to said cellulosic blanket a crosslinking reagent capable of reacting with the cellulosic molecules of said blanket and forming 8 crosslinkages with said molecules, lofting the fabric by mechanical agitation to increase the thickness of the blanket and increase the ratio of the volume of entrapped air to the volume of cellulosic fibers and then curing the crosslinking reagent on said lofted blanket while said blanket has an increased thickness and has the volume of entrapped air to the volume of cellulosic fibers increased.

References Cited by the Examiner UNITED STATES PATENTS 2,080,043 5/37 Heckert 8l 16.3 2,517,529 8/50 Stanley. 2,590,713 3/52 Libbey. 2,950,553 8/60 Hurwitz 8-1163 X FOREIGN PATENTS 265,027 12/54 Australia.

497,647 12/38 Great Britain.

518,167 2/40 Great Britain.

547,846 9/ 42 Great Britain.

NORMAN G. TORCHIN, Primary Examiner.

Claims

1. A PROCESS FOR IMPARTING TO A CELLULOSIC FABRIC THE DESIRABLE CHARACTERISTIC OF MAINTAINING ITS APPEARANCE EVEN AFTER REPEATED LAUNDERINGS AND FOR INCREASING ITS THICKNESS, COMPRESSIBILITY, AND INSULATING PROPERTIES, COMPRISING APPLYING TO SAID CELLULOSIC FABRIC A CROSSLINKING REAGENT CAPABLE OF REACTING WITH THE CELLULOSIC MOLECULES OF SAID FABRIC AND FORMING CROSSLINKAGES WITH SAID MOLECULES, LOFTING THE FABRIC BY MECHANICAL AGITATION TO INCREASE THE THICKNESS OF THE FABRIC AND INCREASE THE RATIO OF THE VOLUME OF ENTRAPPED AIR TO THE VOLUME OF CELLULOSIC FIBERS AND THEN CURING THE CROSSLINKING REAGENT ON SAID LOFTED FABRIC WHILE SAID FABRIC HAS AN INCREASED THICKNESS AND HAS THE VOLUME OF ENTRAPPED AIR TO THE VOLUME OF CELLULOSIC FIBERS INCREASED.