US2169269A - Cellulose acetate crepe yarns and fabrics, and their manufacture - Google Patents

Description

Patented Aug. 15, 1

UNITED STATES PATENT OFFICE CELLULOS James mesne assignments, to Deny, Jersey City, N.

This invention relates to FABRICS, AND

Jersey No Drawing.

E ACETATE CREPE YARNS AND THEIR MANUFACTURE G. McNally, Rochester, N. Y., assignor, by

Eastman Kodak Com- J., a corporation of New Application February ,1, 1936,

Serial No. 62,007

3 Claims.

crepe yarns and crepe fabrics and their production, and more particularly to crepe yarns and fabrics made of organic acid esters of cellulose,

such as cellulose acetate,

5 cellulose propionate, cellulose butyrate, cellulose acetate-propionate, cellulose acetate-butyrate, cellulose acetate-stearate and the like.

It is customary in the art to employ for the manufacture of crepe fabrics highly twisted yarns comprising cotton, natural silk, wool, or the regenerated cellulose type of synthetic yarn,

hereinafter called rayon, and

the highly twisted yarn is referred-to as crepe yarn. Cloth constructions are very well known wherein crepe yarns are used either in warp or filling or both,

but the crepe filling type which condition is largely of production of the present discussion is,

crepe therefore, more particuis the more popular, due to the lower cost filling fabric. The

larly directed to fabrics employing crepe filling yarns and it is understood late generally to warp crepes that the remarks rewith modifications such as are obvious to a textile technician.

For certain novelty effects crepe yarns are used which comprise a mixture of materials such as cotton-natural silk, natural silkrayon, nat-,

ural silk-cellulose acetate yarn, or rayon-cellulose acetate yarn. These mixtures are employed either as separate threads or two threads may be twisted together before pose usually of decreasing weaving for the purthe cost of production of the fabric or of producing cross-dye or other novelty effects. It may be pointed out, however,

that in crepe constructions where cellulose acetate yarn is used in the filling it is used'in conjunction with a crepe filling yarn of some other material and has no active crepe effect.

Cellulose acetate yarns use as warp yarns for crepe part in producing the have found extensive fabrics because of the highly desirable properties of fabrics made with these warps. The

filling yarn usually used in these popular constructions is rayon or natural crepe yarn and the presence of two types of yarn, 1. leads to dyeing difficulties owing to the fact that in general, unaflected by e., cellulose acetate and rayon or silk,

in finishing the goods cellulose acetate yarn is,

dyes for rayon or natural silk and, similarly, dyes suitable for coloring cellulose acetate yam are not'suitable for the other materials. It therefore becomes necessary to use separate dyes stituent yarns of these fabrics,

convenience and added the desirability of elimina for coloring the conwhich is an inexpense. Aside from ting this dyeing dimculty with acetate warp crepes, it has been found that crepe fabrics made entirely of cellulose acetate yarns (both warp enhanced degree the durability, non-creasability, and excellent hand 5 and draping properties which are obtained by using cellulose acetate yarns in the warp alone. In order that the novel features of the instant invention may be clearly apparent, a brief decrepe fabrics are at present 10 made, using rayon or natural silk crepe filling, is

scription of the way and filling) show to an desirable properties of here given, the essential features of such present processes are the following:

(1) Low turn rayon or natural silk yarn is soaked I in a solution of size, the excess solution removed and the yarn dried.

(2) The sized yarn is twisted, usually on an up draft twister, to from 30 to 60 turns per inch,

depending upon the denier of the yarn and 20 the use to which it is to be put. (3) After the operation (2) the yarn has a tendency to untwist.

To overcome this difficulty, the yarn is steamed while wound on spools to set the (4) The filling yarn the customary looms in crepe tions.

(5) The greige goods from jected to a boil off treatment in hot soap solution to remove the twist of the yarn. 5 is wound on cops and used in 2 fabric construc-- the loom are subsize from the yarn; the 30 fabric shrinks widthwise preferentially and develops a pebbled appearance of crepe fabrics. (6) The fabric is dyed characteristic on a winch machine, dried on a slack dryer, and framed out to the desired width on a tentering frame. The finished crepe fabric has two outstanding characteristics: (1) A pebble or rough surface which varies in 40 appearance depending on the type of crepe produced.

(2) Extensibility and elasticity which differentiate the cloth from tightly woven construc- 45 tions such as taffetas or satins.

A popular construction for producing a rayon filled Canton crepe is as follows:

Warp-112 ends per inch, denier dull cellulose acetate inch.

FiZling.-52 picks per inch 50 turns per yarn twisted to yarn, 40 filaments, 4 turns per 50 of denier rayon inch, the filling construction being two picks of right twist yarn alternating with two picks left twist yarn. 55

The greige goods are woven 50 inches wide in the loom.

When this fabric is woven, as indicated, into greige goods and boiled off it shrinks in widthwise from 50 inches to 28-30 inches and develops a bumpy, finely pebbled surface. On framing in the tentering machine, the cloth is brought back to 39-40 inches in width and this represents the finished dimension. The cloth shrinks longitudinally about -15 per cent.

I am aware that the prior art reports many attempts to produce a cellulose acetate crepe yarn. It was first proposed in the art to produce cellulose acetate crepes by substantially imitating the method of producing crepe from natural silk, involving sizing, twisting, setting, weaving and boiling off. Since that time it has been variously proposed to subject the yarn to shrinking treatments before weaving, to treat fabrics woven from cellulose acetate crepe yarns with baths capable of swelling cellulose acetate, to partially saponify the cellulose acetate yarn before twisting, to incorporate water-soluble materials in the cellulose acetate crepe yarn, or to combine cellulose acetate yarns having different degrees of twist, using a relatively low twist in the doubling operation. It has further been proposed to produce cloths of cellulose acetate having a puckered or crepe-like appearance by subjecting cloths woven at least partly of cellulose acetate yarn to treatments calculated to cause differential shrinking of the various yarns contained in the fabric. It may be said, however, that these processes result in such very slight effects as to be scarcely perceptible (widthwise contraction or shrinkage, due to creping, produced in the boiloif, not exceeding 10-15%) and are of no commercial importance, as the resulting fabrics have none of the crepe properties exhibited by the rayon-filled Canton crepe.

Opposed to these teachings of the prior art, I have discovered that in the production of true permit the creping action in the twisted yarn to assert itself.

possible to produce in accordance with my invention, a cellulose acetate crepe, which has a widthwise contraction or shrinkage of approximately 30-50%, which is necessary to produce a true crepe effect in the fabric.

It is, therefore, among the objects of my invention to produce, from cellulose organic acid ester of employing a sizing or any process which thermo-plastically molds the yarn. A further object of my invention is to produce true crepe fabrics.

acid ester yarns, such as cellulose acetate yarns, are satisfactory for crepe yarns, particularly crepe filling yarns, if the twisting operation be carried out while the yarn is in a softened, swollen condition, and the twisted yarn then dried so as to maintain the twist. For the purpose of softening the yarn, I have successfully employed water alone, mixtures of water and other softening agents, aqueous emulsions of vegetable, animal or mineral oils, solutions of soaps or other wetting or dispersing agents, and solutions of colloidal film-forming materials (which have a softening action but not essentially a sizing action) such as gelatin, agar agar, water soluble cellulose esters and water soluble polyvinyl resins. Because of the simplicity of the operation, I prefer to wet the yarn with the desired solution and to twist the yarn in one passage through a down draft twister, but the invention can be carried out on any other type of twisting equipment provided the yarn has been wetted prior to the actual twisting step and has not dried out before the yarn is twisted. For example, the yarn may be wetted by running it through a trough, following which it is passed through a down draft twister or wound on a spool which is put on the spindle of an up-draft twister for twisting, or any other arrangement may be adopted which provides the essential feature of my method.

I have found it desirable in the operation of my invention to avoid excessive stretching of the yarn prior to or during twisting, as the effect is to change the molecular orientation of the fibers in such a way that the desired property of the yarn of being able to assume a spiral configuration (the stable form of the twisted yarn) during an appropriate soaking or boil-off treatment is partly or entirely lost. For that reason, therefore, care must be taken to avoid undue tension on the yarn while being wetted with the softening solution and the conditions on the twisting twisting, the size or denier of the yarn, and the degree of twist being inserted. As a general rule, however, I employ tensions not exceeding 0.15 gram per denier on the yarn; for example, a 100 denier yarn should not be twisted by my method at a tension above grams, in order to avoid the impairment of the valuable creping properties of the yarn.

Following the preferred embodiment of my invention, it is found that the highly twisted and dried cellulose acetate crepe yarn so produced is sufficiently well set that it can be woven without any additional conditioning treatment such as steaming.

Following the preparation of the crepe yarn, it is woven into fabric in the usual manner for crepe fabrics. The fabric is then subjected to a boil-off bath which has a softening action upon the fabric, so as to release the stored potential energy in the twisted thread and permit it to assert its creping effect. During the boil-off treatment, agitation of the fabric is highly desirable in order to assist the yarn to produce the crepe appearance in the cloth.

The following examples of the production of commercially valuable cellulose organic acid ester crepe fabrics, in accordance with my invention,

aieaaco are intended to further the understanding of my invention, but will be understood to be illustrative and not to limit its application, except as defined by the claims appended hereto.

Example I 100 denier cellulose acetate yarn was twisted to 55 turns per inch on a down-draft twister under a tension of grams. Just before the yarn passed through the feed roll of the twister, it was immersed for inches in an emulsion comprising Parts Water 100 Blown olive oil 5 Glycerol 2 Soap 1 washing machine in the following solution:

Parts Carbitol acetate 10 Soap 0.2 Water 100 The fabric shrunk to approximately 30 inches. The fabric was then rinsed, dyed in a dye box, tentered to a width of 40 inches and dried.

Example II 150 denier cellulose acetate yarn was wound onto an updraft twister bobbin and then soaked thoroughly in the following solution:

The yarn was twisted without drying to 50 turns per inch on the up-draft twister at a tension of 8 grams. Right and left twist yarn so prepared was woven into a 50 inch fabric alternating six picks right and six picks left twist yarn at 48 picks per inch, the construction of the warp being 96 sley 150 denier cellulose acetate warp yarn having only a few turns per inch. The crepe appearance was developed by working the fabric with agitation on a dye reel containing the following solution at 40 0.:

Parts Ethyl aceto acetate T 7 Methyl alcohol 10 Sulfonated castor oil 0.5 Soap 0.5 Water 100 The fabric shrunk to 2'1 inches. After this treatment the cloth was rinsed, dried and tentered to a 40 inch width.

Example III 200 denier cellulose acetate yarn was twisted to 48 turns per inch on a down-draft twister as described in Example 1, being wet in thetrough with:

Methyl Cellosolve ethylene glycol) The tension during twisting was 10 grams.

The yam was woven into a 50 inch fabric alternating 4 picks left twist with 4 right twist at 44 picks per inch into a cellulose acetate warp of 120 denier 110 sley. The fabric was dyed and finished as in Example 1, using .the following boil-off bath at 45 0.:

Parts Paraldehyde 10 Ethyl alcohol 10 Water 100 The fabric shrunk to 25 inches and was tentered to 39 inch width.

Example IV 75 denier cellulose acetate yarn was twisted to 55 turns per inch on a down-draft twister, as described in Example I, being wet in the trough with Parts Water 100 Triethanolamine soap 2 Blown sesame oil 10 the tension during twisting being '1 grams.

The yarn was woven into a 50 inch fabric, alternating 2 picks left twist with 2 picks right twist, the warp being 135 sley 75 denier cellulose acetate yarn and the filling construction 58 picks per inch.

The fabric was dyed and finished as in Example I, using the following boil-off bath at 40 0.:

Parts Water 100 Soap- 1 Diethyl carbonate 7 The fabric shrunk to 34 inches and was tentered to 40 inches in width.

The result of the use of the softening bath, in the foregoing examples, prior to twisting of the yarn is somewhat difficult of explanation. Obviously, no softening bath should be employed which actually peptizes or in any way dissolves any portion of the yarn. The purpose of the softening bath is, contrary to the teachings of prior processes, to increase the ductility of the yarn or to decrease the molecular or micellar rigidity of the structural components of the yarn. This permits the molecules or micelles in the yarn, when twisted, to accommodate a larger reversible distortion than is the case when twisting dry yarn. The constituents of this softening bath are so proportioned and the time of immersion of the yarn in the softening bath is so regulated that at substantially the end of'the twisting operation (as the yarn passes through the twister) the thread has substantially dried, or at least has dried sufficiently to set the molecules or micelles in the yarn in their new positions or relation one to the other. Thus the twist in the yarn is set without destroying the reversible distortion therein.

As a general rule, the boil-off bath has a greater softening action upon the fabric than does the softening bath employed prior to twisting. In fact, it will be noted that there is included in the softening baths of the four above examples, components which have a slight dissolving action upon the fabric, although due to the proportion used and the fact that large proportions of nonsolvents are employed, this solvent action is considerably restrained. The reason for employing a boil-off bath of this character is that the warp yarn in the fabric resists the development a slight swelling action upon the yarn, the warp yarn, which predominates upon the surface of the fabric, is softened first, rendered more pliable, and resistance to the creping action relieved; the filling yarn then is acted upon by the boiloff bath, whereupon the set in the yarn is eliminated and the reversible torsion. in the yarn brought into play. Thus, with a soft warp the twisted filling creates the crepe appearance in the cloth. We do not mean to imply that the warp may not also be twisted and thereby obtain additional novel effects; the same explanation would apply.

As a substitute for the above type of boil-off bath, it has been found that water alone may be used for the boil-off if the warp yarn has incorporated therein certain softening agents such as diethylene glycol, Methyl Cellosolve (the mono methyl ether of ethylene glycol) butyl carbitol, butyl lactate, monoacetin, diacetin and the like. When the fabric contains such warp yarn, it is then subjected to the boil-off with plain water or soap solutions, the warp is immediately softened due to the interaction of the water with the softening agent, and the creping action of the filling yarn is then able to assert itself.

While the foregoing examples and most of this specification have employed cellulose acetate yarn as the typical example, it is to be clearly understood that this invention is applicable to and includes the other cellulose organic acid esters, such for instance as cellulose propionate, cellulose butyrate, cellulose acetate-propionate, cellulose acetate-butyrate, cellulose acetate-stearate and the like, and that the examples and directions given herein are equally applicable to all of these esters, except that the softening bath and boil-off bath may have to be altered somewhat to suitably increase or decrease the softening and swelling action of the respective baths, in. order to effect the full teachings of my invention.

I am aware that the wetting of yarn. to set the twist is old in the art. My process, however, is differentiated from this practice in that the yarn is wetted before and during twisting and not after any twist has been inserted. I have found that yarns prepared by the two methods are clearly different in properties and that the necessary condition for the production of satisfactory cellulose acetate crepe filling yarn is that the yarn while being twisted be in a swollen, softened condition.

I am further aware that when cellulose acetate yarn is twisted for crepe yarn following accepted practice for viscose yarn, some slight crepe effects can be obtained in cloth woven from these yarns. It is also well known that a very large number of patents have issued which claim to reveal processes which permit the production of commercially useful crepe fabrics, none of which have been found in actual practice to be at all satisfactory, as the products thereby obtained have little or no permanent crepe effect. Attempts have evenv been made to simulate the appearance of true crepes by embossing crepelike patterns on cellulose acetate cloths and by weaving spiral figures in cellulose acetate cloths, which effects have been used in conjunction with the feeble creping power of yarns prepared by known processes when boiled off by known methods. However, the problem at hand is not the production of some slight waviness or cockled appearance in cellulose acetate cloths, which result could easily be accomplished by weaving design or by embossing flat cloth, but is the production of crepe cloth from cellulose acetate yarns having the desirable appearance and feel of natural silk crepe fabrics, which products are commercially valuable.

Thus, it will be apparent that by my process, it is possible for the first time to produce crepe cloths which are true crepe fabrics and of such a character that they are commercially valuable. By a true crepe is meant a fabric having the appearance, feel and general properties of cloths of similar construction which have long been known and made of natural silk or rayon yarns. By this I do not mean to imply that cellulose acetate crepes cannot be made by my process in new and novel constructions, but I do mean thereby to indicate that by my process the standard crepe constructions can be successfully made and that this invention is not to be compared to socalled crepe fabrics involving the feeble creping ability which has characterized cellulose acetate crepe yarns of earlier processes and prevented their commercial application.

One common feature of true" crepe fabrics is the large widthwise shrinkage they undergo when the crepe appearance is developed in the fabric by an appropriate soaking or boil-off operation. For example, a crepe fabric woven 50 inches wide will shrink widthwise to approx imately -34 inches when the crepe appearance is developed in accordance with my invention, and the cloth also shrinks lengthwise 10-15 per cent. The shrinkage widthwise may in some rare constructions amount to as little as per cent of the original width but in general a widthwise contraction of less than this amount results in an inferior fabric. It is only possible to approach such shrinkage with cellulose acetate filling yarn treated by the old silk or rayon twisting methods and boiling off the fabrics constructed of these yarns by the previously known methods only if the warp construction is made so light that the finished cloth is mechanically very weak and of no use for the customary purposes of crepe fabrics.

The limiting factor to the improvement of crepe appearance by reduction of the number and size of the warp yarns, then, is the strength and ap pearance of the finished cloth; this limit is reached, from a practical viewpoint, when the ratio of the total weight of filling yarn to the total weight of warp yarn is 1:1. Any increase in this ratio will produce a cloth of very poor wearing properties, and although cloth with a somewhat cockled appearance could be made from cellulose acetate yarns prior to this invention, they were of no commercial value.

What I claim is:

1. A process of producing a highly twisted cellulose organic acid ester crepe yarn capable, when woven into a crepe fabric construction, of producing a true crepe effect when the twist is released, which comprises treating cellulose organic acid ester yarn with an aqueous softening and swelling bath having substantially the same swelling effect as water alone and maintained at ordinary room temperature and twisting the yarn with a minimum of stretch while in a softened and swollen condition due to the presence in the yarn of an appreciable amount of water, and setting the twist without thermoplastically molding the yarn by drying simultaneously with or shortly after the twisting operation.

2. The process of producing a highly twisted cellulose organic acid ester crepe yarn capable, when woven into a crepe fabric construction, of

producing a true crepe effect when the twist is released, which comprises treating a substantially untwisted cellulose organic acid ester yarn with a softening and swelling bath consisting essentially of water and maintained at a temperature of approximately 20 C., and twisting the yarn with a minimum of stretch while in a softened and swollen condition due to the presence in the yarn of an appreciable amount of water, and setting the twist without thermopiastically molding the yarn by drying simultaneously with or shortly after the twisting operation. a

3. The process of producing a highly twisted cellulose acetate crepe yarn capable, when woven into a crepe fabric construction, of producing a true crepe effect when the twist is released, which comprises treating a substantially untwisted cellulose acetate yarn with a softening and swelling bath consisting essentially of water maintained at substantially room temperature, and twisting the yarn with a minimum of stretch while in a softened and swollen condition due to the presence in the yarn of an appreciable amount of water, and setting the twist without thermoplastically molding the yarn by drying simultaneously with or shortly after the twisting operation.

JAMES G. MONALLY.