US2249745A - Cellulosic structures and method of producing same - Google Patents

Description

July 22, 1941. 1 w. H. CHARCHEI'AL CELLULOSIC STRUCTURE AND METHOD PRODUCING S AME Filed Dec. 21, 1937 BY M ' ATTORNEY Patented July 22, 1941 CELLULOSIC STRUCTURES AND METHOD OF PRODUCING SAME William Hale Char-ch, Buffalo, and William Frederick Underwood, Amherst, N. Y., assignors to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware Application December 21, 1937, Serial No. 180,976

17 Claims.

This invention relates to new artificial fibers, filaments, threads and the like, and more specifically, to new artificial cellulosic fibers or filaments which possess an inherent and permanent crimp as one of their native properties; to yarns, threads, etc., composed of the same; and to the process whereby crimp-containing, that is, crimpy' filaments, threads and the like are directly spun in the crimpy condition.

The prior art of spinning artificial threads and filaments has been built up on methods which directly and inherently produce straight filaments, in that fine streams of a spinning liquid are forced into a coagulating bath through fine orifices in a spinneret and the formed filaments are drawn away therefrom in substantially straight and parallel fashion, preparatory to their being wound upby a suitable collecting device. The finished product of this art has thus been in the forms of yarns, threads or filamentous masses composed of substantially straight continuous filaments resembling in many respects the straight continuous filaments of natural silk. Alternately it is often required to out these continuous artificial filaments into staple lengths for blending with natural staple fibers or to be used alone in staple spinning processes. However, the basic Properties of the original filaments including their structure and form are in no wise inherently altered thereby.

The nature of the artificial spinning and setting processes employed heretofore has been such as to limit the practice to th spinning of substantially' straight fibers if one would obtain a product showing good strength, elasticity, fineness, luster, and other desirable properties required by the textile trade. In order to achieve a satisfactory product and therewith an economical, smoothly running spinning operation, it has been the practice to eject the spinning solution through the small orifices of a spinneret into a bath which coagulates the spinning liquid, and to draw away the formed filaments from the spinneret and through the coagulating medium at a wind-up speed in excess of the speed straight line from the instant the spinning liquid passes through the spinneret holes. Frequently special devices are employed to accentuate or better control this stretch. The extent of stretch or draw applied varies with different processes, depending upon the strength,

luster, dyeing characteristics, denier, and other properties desired in the finished product. The stretch being applied during the interval of coagulation of necessity causes the thread throughout the process to be subjected to a certain de gree of tension in the direction of its length. The tension, whether developed through the tendency of the thread to shrink, or otherwise, will further act to produce the inherent straight form of the end product. These factors thus combine to produce a fiber whose internal molecular structure is such that it is, or tends to be ipso facto and by nature substantially and permanently straight thereafter, except as new shapes may be mechanically imposed upon it in some later textile operation such as twisting, curling, knitting, weaving, carding, dyeing, drying, finishing, and the like. The commonly employed chemical purification treatments, such as washing, desulfuring, bleaching and the like merely serve to' remove foreign impurities and act in no wise to substantially alter or displace the basic molecular structure and normally straight form which was imposed upon the filaments in their process of extrusion and hardenmg.

When the internal molecular structure of threads and filaments, spun in accordance with the previously known methods describedabove, is observed by means of X-ray diffraction patterns, it is noted that the long molecules of which they are composed lie so as to show a certain preferential orientation in the direction of the fiber axis. Generally speaking, the degree oi orientation observed is the greater according to the greater stretch and/or tension employed while the filaments were being coagulated duning the spinning operation. It is also commonly observed that greater strength in the finished yarn accompanies the greater degrees of molecular orientation. While the extent of orientation may vary, its presence is a common characteristic of artificially spun fibers as heretofore manufactured. Many naturally occurring fibers likewise exhibit preferential molecular orientation in the direction of the fiber axis, but it is generally held that in the case of artificially spun filaments, the molecular orientation results from and is controlled by the stretching and/or tension exerted on them during the period of their formation in the setting baths.

Thus, the spinning processes for artificial filaments have been conducted under a set of conditions wherein the size of the spinning orifice, speed of delivery of spinning liquid through the orifices, the greater speed of draw-off and windup of the coagulated thread, tensions during coagulation, bath compositions, temperatures, and many other factors are all related and controlled to determine the precise characteristics of the final product. While these various factors may be varied at will within certain limits without adverse effects in the finished product, radical departures from conventional practice have been found to result in threads and filaments of no utility as textile products.

If, for example, the conventional process is modified so that one spins without due regard to the speed of drawing off of th filaments from the spinneret orifices, and allows the speed of draw-oil to drop to a small fraction of the speed of extrusion, there is obtained a dull spongy filamentous mass of little tenacity and great fragility. The filaments composing the mass, in addition, will be frequently stuck together and hopelessly entangled. The phenomenon is familiar to those engaged in spinning viscose fibers, in the form of what is known as spinners fiufi or "worms." This abnormal material may be observed just prior to threading up a spinning position at which time the filaments from the nozzle are commonly allowed to issue freely into the bath without being rapidly carried away. A disorganized mass of weak brittle fibers as described above is obtained. Spinners fluff is total waste and is entirely discarded by manufacturers as having no textile utility whatever. Even though these fibers be further processed by careful washing, desulfuring, bleaching and drying, the end product is still very weak and brittle, being usually so fragile as to easily break up or pulverize when rubbed between the hands.

The formation of this spinners fiufif is an excellent illustration of the adverse effects attending a radical departure from commonly accepted spinning practices. It particularly illustrates the importance which has been attached to the maintenance of a proper ratio of extrusion velocity through the spinning orifices to the rate of draw-off of the coagulated threads, wherein the latter is made to exceed the former and thus result in stretch and tension on the thread as it is hardened. It is not surprising, therefore, that great emphasis has been attached to the maintenance and control of these relationships in the manner described, in order to achieve high quality artificial textile fibers of good strength, elasticity, fineness, luster, etc., suitable for the demands of the textil trade.

The previously known artificial fiber products have thus far found a wide range of utility in the field of textiles. However, suitable as they have proven for many types of fabrics, the fact remains that due to the compact and dense nature of threads formed from such inherently and substantially straight fibers, it has been extremely difficult and in many cases impossible to use them in the construction of fabrics where great covering power, fill, light weight, warmth, depth, bulk and other related features were desired. These are the properties chiefly associated with fabrics made from the various natural wool fibers. As a consequence, numerous attempts have been made to impart to such artificial threads and filaments a curled, kinky or crimped form in order to sufficiently change their character in this respect as to permit a wider range of utility. Particularly have attempts been made to impart to artificial staple fibers a certain curl or waviness in order to improve the coherence of these fibers in the textile operations, where they are formed into a loose bat or sliver, either alone or mixed with natural fibers.

In one method the bundle of continuous filaments in the acid set condition is caused to pile up on itself by the use of a scraper held against the draw-off roller in very much the same manner in which crepe is imparted to certain papers. In other processes the continuous filaments are cut into staple lengths after being removed from the acid setting baths, foilowing which the purification operations are conducted on a loose or more or less heterogeneous mass of fibers, thereby allowing them freedom of movement and shrinkage to facilitate their assuming a wavy shape. The fibers are also dried in the loose condition. frequently after opening of the fiber bundles, thereby to aid their heterogeneous character. Either alone or combined with other processes, chemical shrinking agents such as acids, alkalies and other solutions, either hot or cold, have been employed on the loose fibers in order to accentuate their curling. In still other processes, corrugated rollers have been employed at one point or another to impress sinuosities upon the formed filaments and it has even been suggested that artificial threads composed of continuous filaments be twisted to a high number of turns per inch, following which they are steamed and dried and then reverse twisted so as to produce a yarn composed of curly fibers.

All of the many processes devised for imparting crimp to fibers are characterized by the fact that the fibers are originally spun in the conventional manner; that is, as initially straight filaments which are extruded and coagulated with the employment of stretch and/or tension. At some subsequent stage the straight filaments have been submitted to a mechanical and/or chemical treatment for the purpose of imparting a curly or wavy character to them. By virtue of this fact, the curliness is usually temporary, or at best only of a semi-permanent character is regards its crimp regain after wetting, stretching, washing, and similar treatments. Furthermore, the fundamental molecular orientation of the cellulose molecules in the direction of the fiber axis still characterizes these fibers after the curling treatment, since this property is dependent, upon the conditions of tension and/or stretch prevailing between the spinneret and the wind-up device at the time of their formation. They are to be regarded as inherently straight fibers, with the internal structure of such fibers, upon which has been later impressed a curliness or waviness by some after-treatment which does not basically affect their internal structure and characteristics. On a basis of rigid tests, it is found that their curliness or waviness does not tend to persist as a permanent and inherent property under a wide range of tests, treatments and conditions of use. Furthermore, such crimp or curl is not usually, and, in fact for many purposes need not be necessarily, fine or deep, so that as a general rule there is a comparatively small number of undulations per inch.

It has been further proposed to treat fibers, or fiber masses, curled after the production of the fiber, by means of a synthetic resin and/or formaldehyde, for the purpose of setting said curl or waviness, thereby imparting a greater degree of permanence thereto. The urea-formaldehyde, phenol-formaldehyde and other aldehyde resins have been used for this purpose and indeed some progress has been made by such methods in improving the permanence and lasting qualities of the curl. Such methods, however, tend to more or less embrittle the fibers, and to interfere with their normal dyeing properties. The effect on the uniformity of dyeing is such as to make continuous threads treated before weaving or knitting unsuited to most uses. The treatments, therefore, apply primarily to cut staple. That such setting processes are used on curled fibers in order to improve the lasting qualities of their curl is evidence of the semi-permanent and transitory character of the curl when imparted to cellulosic fibers after their original formation in the straight condition. While the permanence of said curl is improved. by such resin treatments, it is recognized that this is not due to any basic structural property of the cellulosic fiber itself, but to the settingeffects of the chemi cal after-treatment in fixing the fiber in its new shape. Indeed the finished product in such cases is no longer a pure cellulosic fiber, but rather a new material structure composed of cellulose and the resin and/or formaldehyde, either chemically or mechanically bound into a composite structure.

In view of the prior art of spinning artificial fibers, which art is built on a recognition of the necessity for spinning straight filaments under conditions employing stretch and/or tension thereon in the setting process, and in view of the known adverseeffects of widely departing from such practice, as is illustrated in the formation of spinners fluff, it is indeed surprising to find that it is possible to directly spin inherently, permanently, and highly crimpy cellulosic filaments of good strength and elasticity and having other desirable properties, by means of the process hereinafter described.

Therefore, it is an object of this invention to providev as a new product cellulosic filaments and threads possessing an inherent and permanent crimp, together with good strength and other desirable physical properties.

It is another object of this invention to produce as a new product cellulosic filaments and threads of good strength possessing an inherent and permanent crimp, which filaments are substantially free from molecular orientation in the fiber axis and which are substantially uncrenulated.

Another object of this invention is to provide very deep, inherently and permanently crimpy cellulosic filaments and threads with crimps formed and persisting in three dimensions, and with a large number of crimps per inch, said filaments possessing good strength and other desirable physical properties.

Still another object of this invention is to provide novel methods of directly spinning crimpy filaments and threads of good strength from suitable cellulosic solutions or dispersions.

Still another object of this invention is to provide novel methods of further processing said crimpy filaments and threads.

Still another object is to provide new and improved coagulating baths suitable for directly spinning highly crimpy filamentous structures of good strength and other physical properties.

Still another object is to provide a process of deepening the crimps in the filaments after they have been formed.

Other objects will be apparent from the description that follows.

The invention will be more easily understood by reference to the following detailed description and the accompanying illustrations, in which, 7

Fig. 1 is a copy of a highly magnified photographic cross-sectional view of a plurality of crenulated filaments produced by the conventional stretch-spinning process in which the filaments are spun in an active regenerating bath.

Fig. 2 is a copy of a highly magnified photographic cross-sectional view of a plurality of substantially uncrenulated filaments produced in accordance with the present invention in which the filaments are spun in a fast acting coagulating bath which has a slow or delayed regenerating action.

Fig. 3 is a diagrammatic cross-sectional view of a simple form of apparatus suitable for use in carrying out the process of this invention.

The present invention comprises a new cellulosic fiber possessing inherent and permanent crimps in three dimensions, said fiber possessing substantially no molecular orientation in the direetion of the fiber axis, and showing good strength, elasticity, and other desirable physical properties. This invention further comprises the process of spinning said inherently crimpy fibers, wherein fine streams of a spinning solution are forced through the orifices of a spinneret into a suitable coagulating medium at a speed several or more times greater than the rate at which the coagulated threads are drawn off and removed from the coagulating medium, whereby the filaments spontaneously assume their finely crimpy form immediately upon issuing from the spinneret orifices into the bath, 'said form persisting as one of their permanent structural characteristics. The invention further comprises the use of an initial setting bath with a strong and rapid precipitating, coagulating and/or dehydrating action with substantially no regenerating action, or only a slow or delayed regenerating action, in combination with a set of spinning conditions wherein the jet velocity of the spinning solution through the orifices is several or more times greater than the rate of removal of the formed threads from the coagulating bath, preferably followed by a treatment to complete the hardening or regeneration of the filaments in the crimpy condition.

Referring to Figure 3 of the drawing, the cellulosic spinning solution is extruded through the orifices of spinneret l3 into a fast acting coagulating bath M. The crimpy filaments l5 are passed over guide rolls l6 and i1 and then onto a windup roll I8 which is driven at a speed to move the thread at a substantially uniform rate of speed. The speed of the thread as it is being drawn from the bath of the windup roll 18 is the draw-off speed of the thread. This draw-off speed of the thread is maintained much lower than the jet velocity of the spinning solution issuing from the orifices so that the filamentous solution as it flows from the spinneret buckles and bends as it is forced into the bath.

The threads or filaments thus produced are thereafter washed. desulfured, bleached, or otherwise purified by known methods. Prior to the final drying of the threads or filaments. they are given a treatment with a finishing solution such as may be composed of oils, soaps, sulfonated oils, and the like. After freeing the threads or filaments from excess adhering solution, they are dried in a free, loose condition, for instance in the form of skeins, and preferably with the employment of some agitation during the drying process. Such agitation may be supplied by currents of moving air or by suitably acting mechanical devices, or both, or by other well known agitating means.

Quite surprisingly it has been found that a depending and accentuation of the crimps of the fiber can be obtained by submitting the formed crimpy threads or fibers to a stretching treatment in the wet state and thereafter relaxing the stretched thread, said treatment being applied at any time following completion of the regenerating step. The amount of stretch employed may vary from a few per cent up to as much as 40 or 50 per cent, or in some cases even more. Indeed, it has been found possible to stretch the threads or filaments to just short of their breaking point, thereafter completely relaxing the thread, further processing, and finally drying it still in the relaxed condition to obtain filaments with greater depth of crimp. The amount of stretch, which is here referred to, and which is employed, is in addition to that required to just straighten out the original crimps in the filaments. The amount of relaxation after stretching is sufiicient to completely relax the threads and it is allowed to take place, before further processing and drying. While it might be supposed that such drastic stretching would result in completely and permanently destroying the crimpy properties of the fibers, it is found on the contrary, that the general character and the permanence of the crimp is not adversely affected thereby, but indeed upon drying the yarn relaxed and with external agitation, it results that the depth of the crimps is usually somewhat improved over what it would have been in the absence of such stretching treatment. While this stretching treatment is optional, in the preferred form of process the yarn will usually be subjected, at some stage fol lowing completed regeneration, to a certain stretch, as by nipping it between sets of rollers rotating at different speeds or by other suitable devices, or by devices which stretch an entire skein, and the like. The stretching is preferably carried out on yarn or filaments which are thoroughly wet with water or water containing finishing materials, and at room temperature. If room temperature or slightly chilled water is employed, a greater degree of'stretch may usually be imparted-than can be achieved by the use of hot water. If the stretching is carried out just prior to the final drying of the yarn, it may be convenient to wet or rewet the yarn with water containing a small amount of finishing agents, such as soaps, sulfonated oils, emulsions of oils, lubricants and other finishing agents commonly employed on artificial fibers. In other instances the stretch may be applied during the washing or purification steps which follow coagulation and regeneration. In this case, the threads are processed singly and continuously on suitable machines for the purpose. The fact that the threads or fibers can be submitted to such severe stretching as above described and will not only still regain their original crimp, but may be frequently improved thereby, is remarkable evidence of the inherent and permanent character of their crimp which distinguishes them from crimped or curled fibers heretofore produced.

Throughout this specification the jet velocitydraw-off ratio is frequently referred to. This expression is used for convenience and refers to the ratio of the velocity of spinning fluid through the spinneret orifices to the speed at which the coagulated and formed threads or filaments are drawn through the coagulating bath and away from the spinneret.

The several specific examples that follow will serve to illustrate the details of the invention, but it is to be understood that these examples are in no way limitative of the invention.

Example 1 Viscose containing 7% cellulose and 6% sodium hydroxide, ripened to a salt index of 4.2, was extruded at the rate of 8.50 grams per minute through a spinneret having 40 holes, each hole being .004" in diameter, into an aqueous coagulating bath containing 44.3% ammonium sulfate and 0.3% ammonium hydroxide at a temperature of 45 (2., whereby the filaments composing the thread were coagulated and spontaneously assumed a crimpy form at once upon issuing from the spinneret. The thread was drawn 20 inches through the bath, and wound onto a bobbin at a speed of 227" per minute. Since the jet velocity was equal to 930" per minute, the ratio of jet velocity to draw-oil was about 4.1.

The thread was thereafter regenerated by immersing the bobbin of yarn in an aqueous bath containing 20% sulfuric acid, 18% sodium sulfate and 10% glucose at 25 C. The yarn still on the bobbin was washed with soft water to free it from acid, desulfured in a hot dilute sodium carbonate solution, and finally washed free from alkalinity with soft water. The wet yarn was given two turns per inch of twist on a ring twisting machine, following which it was reeled into skeins while still wet. The skeins were then immersed in a hot aqueous finishing solution containing a sulfonated oil, freed from excess solution by centrifuging wringing, and then dried in a relaxed condition while agitating the skeins by means of moving air and mechanical movement of the skein itself.

The resulting yarn was substantially uncrenulated, was substantially free from molecular orientation along the fiber axis, and possessed a three-dimensional crimp which was retained upon repeated wetting and drying of the yarn and under conditions of use.

Example 2 Viscose such as described in Example 1 was extruded at the rate of 28.69 grams per minute through a spinneret containing holes, each hole being .0015" in diameter, into a bath having the same composition and at the same temperature as was used in Example 1, and after 20" of travel in the bath the crimpy yarn formed was wound up at a speed of 598" per minute. The nozzle velocity was 8900" per minute, giving, therefore, a ratio of jet velocity to draw-01f speed of about 14.9. This yarn was regenerated, purified, dried, and otherwise finished in the manner described in Example 1.

Example 3 Viscose such as described in Example 1 was extruded through a nozzle containing 40 holes, each hole being .002" in diameter, at the rate of 4.7 grams per minute, into a bath of the same composition and at the same temperature as used in the above examples and after passing 20" through this bath the crimpy yarn thus produced was wound up at 372" per minute. This represents a nozzle velocity of 2055" per minute, and, therefore, a ratio of nozzle velocity to draw-ofl speed of about 5.5. After regenerating, desulfuring, and twisting, as described under Example 1, the wet yarn was stretched 50% over and above that stretch necessary to just straighten out the crimp, and then wound onto a bobbin in a relaxed condition, following which it was reeled into skeins and was then finished and dried in the manner described in Example 1.

The yarn so produced was woven on a commercial loom using 36/2 spun rayon as a warp, warp spacing 74 ends per inch, and a 2/2 serge weave with a filling of the above yarn, using 53 picks per inch. This cloth was given commercial dyeing and finishing treatments. The resultant cloth due to thecrimp in the filling yarn, possessed an appearance and hand similar to that of a worsted fabric. When the cloth is viewed under a five power hand magnifying glass the improved filling power of the crimpy yarn is readily noted.

Example 4 Cotton linters viscose containing 7% cellulose and 6% sodium hydroxide, having a salt index of 0.5 was extruded through a spinneret having 100 holes, each hole being .002" in diameter, at the rate of 20.85 grams per minute, into a coagulating bath containing 43.89% sodium sulfate and 0.13% ammonium hydroxide at 45 C. The crimpy yarn thus formed after passing 20" through the bath was wound up at a draw-off speed of 474" per minute. After the spinning cake was completed, the yarn on the bobbin was Example Cotton linters viscose containing 7% cellulose and 6% NaOH, having a salt index of 4.0 to 4.2, was extruded at the rate of 20.06 grams per minute, through a spinneret containing 100 holes, each hole being .002" in diameter, into a bath containing approximately 45% ammonium sulfate and 0.3% ammonium hydroxide at 45 C., and the erimpy yarn thus formed after 20" bath travel was wound up on a bobbin at the rate of 385" per minute. The nozzle velocity was 3520" per minute, which meansthat the ratio of jet velocity to draw-off speed was about 9.1. The coagulated yarn was regenerated on the bobbin, was washed and purified as in Example 1. The wet yarn was given 2.75 turns per inch of twist on a ring twister and then while still wet was stretched 50%, wound into skeins, finished, and finally dried in a relaxed and agitated condition, asdescribed in Example 1. This yarn was woven on a commercial loom, using a 6/1 warp thread made up of 85% 5.5 denier per filament dull spun rayon and 64 wool with 26 .ends per inch and with the yarn of this example as the filling thread at the rate of 15 picks per inch, to form a plain weave fabric. The resultant fabric was given the same commercial finishing treatment as that used for the fabric described under Example 3. This fabric, due to the great covering power of the bulky and lofty crimpy filling yarn, when compared with a fabric of the same construction but made with a filling yarn similar to that of the warp threads, and finished in exactly the same manner, showed considerably more body.

Example 6 Cotton linters viscose containing 7% cellulose, 6% sodium hydroxide, having 'a salt index of 4.0, was extruded at the rate of 20.75 grams per minute, through a spinneret containing holes, each hole being .002 in diameter, into a coagulating bath of glacial acetic acid at room temperature and after passing the crimpy yarn formed 20" through the bath, it was wound up on a bobbin at 340" per minute. The resulting yarn was regenerated slowly as spun, and, therefore, required no subsequent regenerating treatment. The yarn was washed, desulfured, and twisted to two turns per inch, as previously described, and then without drying was stretched 50%, reeled into skeins, finished, and finally dried in a relaxed condition as described in Example 1. The yarn so produced possessed an excellent three-dimensional crimp, a semi-dull or silk-like luster, andwas quite soft.

Example 7 The viscose as described under Example 6 was spun in the same manner as in Example 6, except that an aqueous coagulating bath containing 40.5% ammonium sulfate and 1.12% acetic acid was used at 45 C. The viscose delivery was 20.23 grams per minute and the windup speed was 474 per minute. The crimpy yarn produced was not regenerated by this spinning bath but was regenerated on the bobbin by a bath consisting of 20% sulfuric acid, 18% sodium sulfate, and 10% glucose at 25 C. After washing, desulfuring, and twisting to two turns per inch in the manner described in Example 1, the yarn was wet stretched 40%, was reeled into skeins, finished, and then dried in a relaxed condition as described in Example 1.

Example 8 This example was carried out in the same manner as Example 7, except that the coagulating bath contained 40.5% ammonium sulfate, 0.93% sulfuric acid at 45 C., and the windup speed was 438" per minute. Although the crimpy yarn produced was slowly regenerated by this spinningbath, it was afterward immersed in 20% sulfuric acid, 10% glucose, and 18% sodium sulfate bath at 25 C. to hasten regeneration. The yarn was further treated and finished in the manner as described in Example 7.

Example 9 Viscose containing 7% cellulose and 6% sodium hydroxide, ripened to a salt index of 4.2 was extruded at the rate of 20.7 grams per minute through a spinneret having 100 holes, each hole being .002" in diameter, into an aqueous coagulating bath containing 5.75% sulfuric acid and saturated with ammonium sulfate at 45 C. The filaments composing the thread assumed a crimpy form at once upon issuing from the spinneret. The thread was drawn 20 inches through the bath and wound onto a bobbin at a speed of 438 per minute. This represents a nozzle velocity of approximately 3620" per minute. Therefore, the ratio of nozzle velocity to draw-off speed Was about 8.27. The yarn was regenerated as wound up on the bobbin, but in order to assure completion of the regeneration the bobbin was immersed in an aqueous bath containing 20% cose at 25 C. The yarn still on the bobbin was washed with soft water to free it from acid, desulfured in a hot dilute sodium carbonate solution, and finally washed free from alkalinity in soft water. The yarn, while still wet, was given 2 turns per inch on a ring twister, following which it was wet reeled into skeins. The skeins were then immersed in a hot aqueous solution containing sulfonated oil, freed from excess solution by centrifugal wringing, and then dried in a relaxed condition while agitating the skeins by means of moving air and mechanical movement of the skein itself. The resultant yarn was substantially uncrenulated, substantially free from molecular orientation along the fiber axis, and possessed a three-dimensional crimp which was retained upon repeated washing and drying of the yarn and under conditions of use.

Example 10 A methyl cellulose containing /2 mol of methyl for each six carbon atoms of the cellulose molecule was dissolved in 7% sodium hydroxide solution at C. to yield a 7% methyl cellulose solution. This solution was extruded at the rate of 20.7 grams per minute through a spinneret containing 100 holes, each hole being 0.002" in diameter, into an aqueous coagulating bath containing approximately 45% ammonium sulfate, 0.3% ammonium hydroxide and 10% glucose at 45 C. and the crimpy yarn thus formed was wound up on a bobbin at 340" per minute. The jet velocity was about 3620 inches per minute, resulting in a ratio of jet velocity to draw-off speed of about 10.6. The coagulated yarn while still on the bobbin was then immersed in sulfuric acid, 18% sodium sulfate, and 10% glucose bath at C. for 10 minutes, and then washed, purified, twisted, skeined, finished, and dried as described in Example 1.

Example 11 A viscose solution containing 7% cellulose, 6% sodium hydroxide, ripened to a salt index of 4.0, was spun into a saturated solution of sodium sulfate at 45 C., using a spinneret containing 100 holes, each hole being 0.002" in diameter, and a viscose delivery rate of 20.75 grams per minute. The crimpy yarn was passed through 20 inches of bath and wound up on a bobbin at 313" per'minute. The jet velocity was about 3630" per minute, which gave a ratio of jet velocity to draw-off speed of 11.6. The resultant.

yarn was regenerated, purified, twisted, skeined, finished, and dried in the manner described in Example 1.

Example 12 Viscose containing 4% cellulose and 3.45% sodium hydroxide was extruded at the rate of 4.81 grams per minute through a spinneret containing holes, each hole being .002" in diameter, and after passing about 20" through a. ammonium sulfate bath at 45 C., the crimpy coagulated cellulose xanthate yarn was wound up on a bobbin at the rate of 238" per minute. The jet velocity was 2103" per minute, which resulted in a ratio of jet velocity to draw-off of about 8.8. The yarn was regenerated and otherwise treated in the manner described under Example 4.

Example 13 Viscose was prepared in the usual manner from wood pulp to produce a solution containing 8.5% cellulose and 6.5% NaOH and after ripening to a salt index of 1.9 was extruded at the rate of 20.35 grams per minute through a hole spinneret, each hole being 0.002" in diameter, into the same coagulating bath described in Example 12 to produce crimpy yarn and after passing 20 inches through the bath the yarn was wound up on a bobbin at 535" per minute. The nozzle velocity was 3560 per minute, resulting in a ratio of jet velocity to draw-off of about 6.6. The yarn was regenerated and otherwise threaded in the manner described under Example 4.

For convenience the invention has been largely described in its application to the production of regenerated cellulose fibers and filaments as produced by the viscose process. It is to be understood, however, that it is not limited thereby, but the principles of the invention may be applied to the spinning of cuprammonium cellulose threads and filaments and other cellulosic threads and filaments by other processes. An example for the spinning of methyl cellulose filaments has been given. In similar and appropriate manner one may, in accordance with the present invention, spin crimpy filaments from other coagulable aqueous cellulosic filament-forming solutions or dispersions.

In applying this invention to the spinning of crimpy filaments from viscose use may be made of any viscose suitable for the spinning of the usual prior art threads or fibers, or any especially prepared viscose coagulable in aqueous or non-aqueous setting baths. ,In practice, particularly desirable results are obtained by use of a viscose prepared in the usual manner and ripened to a salt index of from 2 to 4%, determined as described on page 68, paragraph 2 of "Artificial Silk" by Reinthaler and Rowe, published in 1928. To regulate special effects, however, such as softness and harshness, or luster or dullness, viscose with an index as high as 9, and as low as 0.5 has been spun with the production of good crimpy filaments. It is also possible to use a viscose modified by the addition of well known modifying agents such as delustering agents, including pigments, as well as liquid and organic delusterants. It is furthermore possible to employ viscose modified by the addition of materials which aifect or influence any one of the many dyeing properties of the spun fibers. Where fiber dyeing is desired having a susceptibility to acid dyes such as are commonly employed in the dyeing of wool, various dye modifiers, such as are commonly employed for this purpose may be added to the viscose. Viscose may be otherwise further modified for still other purposes and when spun by means of the invention will produce inherently, permanently, and highly crimpy threads or filaments.

As previously pointed out, a high ratio of jet velocity to draw-off speed is essential to and a part of the invention. The jet velocity is several or more times greater than the draw-off speed of the filaments. For spinning very crimpy filaments, the jet velocity-draw-ofi ratio is preferably and approximately at least four when employing the usual types of viscose and setting baths, as described herein. The jet velocitydraw-oif ratio may be as high as 5, 8, 10, 12, 20 or even higher, depending upon the special effects desired in the finished yam and/or the special properties of the viscose and/or coagulating baths employed. It will also depend upon the diameter of the extrusion orifices in the spinneret, as well as upon the diameter of the filaments to be spun. For instance, in the spinning Another reason for requiringbath of powerful coagulating properties is to avoid stuck filaments. Baths which coagulate slowly do not set up the crimpy filaments sufiiciently to prevent them from sticking to each other after extrusion.

The usual range of bath temperatures may be employed or the temperature of the bath may be substantially increased or lowered without departing fromthe invention. Temperatures between 40 and 50 C. are commonly used.

The formation of crimpy filaments spun in the manner described above takes place immediately, or almost immediately following the issuance of the streams of spinning solution from the spinneret orifices. Usually the formation of these crimps will have been completed within the first inch or less of bath travel, subsequent travel being used largely to complete hardening and setting and/or to initiate the regeneration step as when the bath may be weakly acidic, as above described. In causing the fine streams of spinningsolution to curl and buckle back upon themselves directly upon issuing from the spinning orifices, meanwhile acting on them by means of a rapidly coagulating bath, a crimp which is based, so to speak, upon the molecular structure of the fiber itself is obtained. By carrying out regeneration of the filaments in their original crimpy .shape, the internal molecular structure of the filaments has been further and finally fixed so that their natural form is crimpy, as distinguished from prior art fibers whose natural form has been straight.

When employing an initial setting bath of substantially no regenerating action, or in some cases when employing an initial setting bath of slow ordelayed regenerating action, the coagulated threads are introduced into a regenerating bath of pronounced acidic properties. For this step the stronger mineral acids are preferred; for example, sulfuric acid in concentrations, for instance, between about 10 and 20%, or higher.

As a rule, it is preferred to use an acid bath containing substantial quantities of some salt such as sodium sulfate or other materials of coagulating eflfects such as glucose. A bath containing approximately 20% sulfuric acid, 18%

sodium sulfate, and 10% glucose at room temperature serves very well to regenerate the filaments and to yield softness in the final product. In many cases acid baths containing higher concentrations of salt maybe used to good advantage and where greater softness is desired. As a rule, baths at or near room temperature appear to give somewhat softer yarn than very high temperature baths, although one may operate as high as 40 or 50 0., if desired. One may, of course, regenerate by other suitable means, as by the employment of heat, or by the employment of acidic gases or vapors, such as sulfur dioxide, or by combinations thereof, as well as by other means. When employing an initial setting bath composed of, or containing substantial amounts of an organic acid coagu lant such as acetic acid, or when spinning into an initial bath of very slow or delayed regenerating action, one may, if desired, omit the separate regenerating step, provided that due recognition is given to the use of conditions which permit completion of regeneration of the cellulose xanthate filaments, as by giving the filaments a sufliciently long time in the bath, the use of higher bath temperatures, etc.

After regeneration, the yarn is washed in any convenient manner, as, for instance, by immersion, showering, methods. It is desulfured by means of any of the usual desulfuring agents such as a dilute solution of sodium carbonate, sodium sulfide, or the like. The yarn desulfurs very easily to a good color and for many uses may require no bleaching, but it may be bleached if desired.

The purified yarn may then be twisted to 2 or 3, or any desired number of turns per inch, either prior to or after drying. In twisting wet yarn, use is preferably made of a ring twister, or to twist by means of feeding the yarn into acentrifugal spinning bucket. lulose yarn is twisted andcollected in a centrifugal bucket as a cake, further processing of the yarn may be carried out in that form, if desired. The yarn can, of course, be first dried and thereafter twisted on suitable machinery.

In the drying of the-threads or fibers, due precautionsshould be exercised to preserve their crimpy form and to facilitate the development of a still further depth of crimp during the drying process. The fibers of the invention not only preserve their crimp on drying, but, indeed, during drying assume an even more highly crimpy form. Therefore; the drying is conducted in such a manner as not only not to interfere with the development of such crimp, but to facilitate its further formation. It is naturally desired to obtain a finished dried product of great bulk and flufiiness.

It is, therefore, preferred to apply a finishing or lubricating material to the yarn prior to its being dried. Such finishes are composed of soaps,

oils, emulsified oils and fats, sulfonated oils, mineral oils, and other agents well known in the art of finishing textiles. It is preferred to use a finish which will permit maximum lubrication and slipping of the threads and filaments over each other during the drying process. The finishes are applied in such amounts as to add from a fraction to several or more percent of materials to the yarn based on a dry weight basis. The yarn, after finishing, may be dried in the form of skeins into which form it is reeled while still in the wet condition. Since considerable contraction of the threads takes place ,due to further crimp formation during drying, it is necessary to reel initially a rather large diameter skein so as to compensate for its contraction during the drying process. It is preferable to dry the product whether in skeins or other forms, by means of moving air, which furnishes continuous or frequent agitation of the threads and filaments thereof. It is furthermore preferable to employ mechanical devices which agitate, turn, or otherwise cause continuous or frequent movement of the yarn, thus facilitating freedom of movement of the individual threads and filamentsover and past eachother in their contraction during the drying processes. In drying the skeins may contract to as much as 25 to 50%, or more of their original wet length, due to further crimp formation. It is preferred to dry at a relatively slow rate and while one may employ highly heated air, it is usually preferable to conduct the drying at a much slower rate, as by'means of air at room temperature, or only slightly heated, combining therewith suitable agitation, movement, or working of the skein. Alternately, the product may be dried in continuous form, as by passing the individual threads through any suitable drying chamber. Agltation of the threads by mechanical means and/or moving air is employed to allow contraction of the threads during or by centrifugal or pressure If the regenerated celof very heavy denier crimpy filaments measuring as much as 20 or .30 denier per filament, the jet velocity-draw-oif ratio may be as low as four, while for the spinning of much finer filaments such as filaments of or 6 denier or less, it has been found desirable to use a very much higher jet velocity-draw-off ratio, frequently as much as fifteen, twenty, or even more. In general, the jet velocity-draw-off ratio for most yarns will be between four and twenty.

The character of the initial coagulating or setting bath in which crimpy filaments of good strength are formed by spinning with a high jet velocity-draw-off ratio is a further necessary part of the invention. A fast-acting coagulating bath with no regenerating action, or, alternatively, one with a delayed or slow regenerating action is employed. Such a bath may be defined as one with very strong dehydrating, salting out, or precipitating action, such as to cause the streams of viscose issuing from the spinning orifices to be completely coagulated throughout, or substantially so, before any substantial regeneration is initiated. By thus separating the steps of coagulation and regeneration in the spinning of filaments by the use of a high jet velocity-draW-off ratio, we obtain permanently crimpy filaments of good strength which possess a substantially smooth uncrenulated surface, and show substantially no molecular orientation in the direction of the fiber axis.

The above may, for example, be accomplished by the use of a bath comprising a high concentration of a highly soluble salt or a high concentration of a weak acid containing such a small amount of water as to give a strong dehydrating or precipitating action. An aqueous, saturated or nearly saturated ammonium sulfate bath at approximately 45 C. is an excellent coagulating medium. Other highly soluble ammonium salts may likewise be used in high concentrations; for instance, ammonium chloride, ammonium carbonate, ammonium phosphate, and the like as well as other active coagulating salt solutions such as a saturated sodium sulfate solution. Such baths may be used either with or without the addition of other salts.

For commercial practice, an ammonium sulfate bath of high concentration at or near saturation is preferred. It is usually preferred to maintain this bath at or near neutrality. Under these conditions threads composed of a large number of highly crimpy filaments can be spun, which filaments show no tendency to stick together. When a somewhat lower percentage of salt is employed in the bath, it may be necessary to use a large faced spinneret in which the holes are spaced wider apart so as to permit free access of the setting bath to the immediate vicinity of the spinneret holes, thereby suppressing the tendency of filaments to stick together.

Alternatively, the initial coagulating bath may be operated with several or more percent active mineral acid, such as sulfuric, providing that the bath contains a sufficiently high concentration of salt, or other material, of active coagulating properties as to cause substantially complete coagulation of the spinning fluid before the initiation of any substantial amount of regeneration. With such a bath, the acid concentration may be of the order of several percent or more of mineral acid. Under certain conditions it has been found possible to spin crimpy filaments of good strength into baths containing as much as 5%, or even 7%, sulfuric acid while maintaining an ammonium sulfate concentration at or near the saturation point. When, for example, use is made of a strongly precipitating salt bath of high concentration and containing several or more percent mineral acid, the activity of the acid as regards its regenerating properties is diminished. as a result of the high salt content. Furthermore, the coagulating, precipitating, or salting out action of the bath is enhanced as a result of the high salt content. Active regenerating acid baths such as have been used in the ordinary spinning of straight filament rayon cannot be used in this process since in combination with high jet velocity-draw-off ratio they have adverse effccts on the strength, elasticity, and other properties of the fibers, and no claim is made for this type of bath as the initial setting bath for the spinning of crimpy filaments.

Alternatively, as other baths suitable for this process, it has also been found useful to employ organic acids, either alone or containing some minor percentage of water with or without the addition of salts and the like. Organic acids such as acetic, formic, citric and the like may be employed as the initial bath. Glacial acetic acid containing small amounts of water, possesses marked coagulation properties for the spinning of the crimpy filaments and it is sufiiciently slow in its regenerating action as to produce strong, soft crimpy yarns of good properties. With such a bath it may be unnecessary to submit the formed filaments to a second and stronger acid bath to complete regeneration, although this can be done if desired.

It is, therefore, apparent that considerable variation in constituents, ranges of constituents, temperatures, and other factors can be made in the baths to be used for the coagulation of the filaments of the present invention. The coagulation and regeneration of the filaments are kept more or less separated from each other in point of time so that coagulation throughout the fiber precedes any substantial regeneration. Baths which operate in this manner produce filaments which are substantially smooth and non-crenulated, as opposed to the highly crenulated filaments produced by baths customarily used for spinning straight filament viscose rayon and wherein regeneration of the filaments takes place before the filaments have been coagulated throughout.

Referring to Figures 1 and 2 of the accompanying drawing reference numeral ll designates the highly crenulated straight filaments of the prior art. Numeral l2 designates the substantially non-crenulated filaments of the present invention. The cross-sections of the filaments in both views are drawn from actual magnified photographs of the corresponding filaments. The crenulations of the prior art filaments are brought about by the fact that the outer shell of the filament has become regenerated before the inher fluid core has become coagulated. Thus, by the time coagulation of the interior of the filament has been completed there occurs a collapse of the filament with the result that the outer, already regenerated skin shrinks and shrivels to form a filament with a highly crenulated surface. On the other hand, the rapid coagulating-slow regenerating baths of the present invention cause complete coagulation throughout the filament before any substantial regeneration takes place and as a result no outer collapsible skin is formed, but the structure tends to maintain the circular outline which it had when originally coagulated.

drying. A skein of the yarn thus processed, will possess from 2 to 5, or even more, times the bulk of prior art straight filament yarns.

While the above description of the process relates to the production of a continuous filament yarn composed of permanently crimpy filaments, the continuous filaments may, if desired, be cut into staple of any desired length, either in the wet or dry state, or at any convenient stage in their processing. It is to be understood for the purpose of the specification and claims that the terms filaments, fibers," threads, and the like are intended to cover the product and proc-' ess for the same, as relating to both continuous lengths and short staple lengths.

The filaments, fibers, threads, yarns, etc., of the invention are distinguished from other artificial fibers in many important respects. Their outstanding characteristic is an inherent and permanent crinkle or crimp which is regained after wetting and drying, and other treatments, even though the filaments or yarns thereof may become stretched so as to temporarily remove their'crinkle, as hereinafter described. The fibers of the present invention possess a relatively large number of small and very pronounced un dulations which, ofcourse, will vary in size and spacing according 'to the specific method of spinning, but will generally amount to from or less to 50, or more crimps per inch. It is characteristic of the fibers that their crimp lies naturally in three dimensions rather than a single plane or nearly so, as is the case with straight filament yarn upon which crimp has been superimposed by 'means of gears and similar devices. Furthermore, as a result of the particular method of spinning, the crimps in the various filaments issuing from an orifice are formed and quency roughly approximating that of the frequency of the crimp in the fibers.

The filaments or fibers are further distinguished as a whole by a substantially smooth, non-crenulated surface and the shape of their cross-section is on the average usually nearly round, or not greatly distorted from a round remain out of phase with each other. This is advantageous in yielding threads or yarns of great bulk, loft, covering power and resiliency, similar in many respects to woolen yarns. A more detailed description of the permanent nature of the crimp of thefibers is given later herein. i

The filaments or fibers of the present invention are further distinguished by observing their X- ray diffraction patterns, which demonstrate that their molecular structure shows no preferential orientation of the molecules or micelles in the direction of the fiber axis. While the fibers show a crystalline structure common to all regenerated cellulose fibers, there is an absence of orientation effects. The fibers are further distinguished by their appearance in polarized light, when viewed through a polarizing microscope. Viewed in this manner, they show distinct, frequent, and abrupt alternating colored and uncolored patches, more or less regularly disposed in the long direction of the fiber. Prior art filaments and fibers which have been spun and set in a straight condition with stretching and/or tension during the spinning process, whether or not they have been subsequently crimped, show color effects throughout their entire length, and while these colors may change or gradually blend one into the other, or sometimes even gradually fade out and then reappear over a comparatively long fiber length, in no case has a frequent and sharp alternation been observed between colored and completely uncolored patches such as may be observed in the fibers of the present invention. The rapidly alternating colored and uncolored patches characterizing the fiber occur with a freshape. In some instances, very fine crenulations are observed on the surface. These are, however, extremely fine when they occur and do not substantially approach the appearance of prior art straight filament viscose fibers which are deeply and highly corrugated. In the preferred forms of the invention, the fibers are substantially round and possess a substantially smooth surface.

The filaments or fibers are further characterized by a subdued luster or matt appearance, which is obtained without the addition of any foreign delustering agents such as pigments, oils, and the like, heretofore employed for the purpose of delustering straight filament rayon. Such foreign delustering materials may, of course, if desired, be added to the .viscose prior to spinning in order to achieve still greater or special low luster effects, but for many purposes for which the fiber is used, this will be unnecessary, since a fiber with a subdued luster is obtained directly as a result of the method of spinning as hereinabove set forth. By suitable changes in the degree of ripeness, of the viscose and/or in the coagulating bath composition and/or the jet velocity-draw-ofi ratio, the luster effects in the final product may be varied through a wide range.

The filaments or fibers are further distinguished in their great ability to absorb dyes as compared to prior art straight filaments spun with stretch and/or tension. When compared to such prior art cellulosic filaments, the product dyes many shades deeper and much more rapidly, such comparisons being made under comparable dyeing conditions. This is an advantage in commercial processing due to the rigid economic factors which prevail in the dyeing and finishing industry.

The filaments, or yarns composed thereof, notably possess good strength, elasticity, and softness, the latter being more apparent in the finer filament deniers. In the medium or somee what higher deniers, the yarns possess a very desirable property which may be termed crispness of hand." This crispness has been found to be advantageous and to carry over and appear in the finished cloth. A twill or other woven fabric, for instance, possesses distinctly more body than when. constructed from prior art continuous straight filament threads or spun staple threads of corresponding denier. The dry strength of the fibers produced in the manner herein described will range from about 0.5 G. P. D. up to 1.25 G. P. D., or in special cases even somewhat higher. As is usualin the case of regenerated cellulose filaments, the wet strength is roughly half of the dry strength. The filaments, or threads composed thereof, however, show an unusually high elongation, both wet and dry, as compared to prior art straight cellulosic filaments spun with stretch and/or tension. The dry elongation of the filaments will be between 35 and 45% and the wet elongation in the neighborhood of twice that figure. Frequently these figures are exceeded, depending upon the method of preparation. While the strength of the fibers is somewhat lower than that of usual tension spun straight artificial filaments, it is sufilcient for the uses to which the product is applied, and, indeed, is very favorably comparable to, or better than the strength of comparable wool fibers and yarns. The product may be produced in a wide variety of deniers per filament, ranging from very small filaments of 3 or 4 deniers per filament, or less, up to 20, 30, or even more deniers per filament. As is usual in the case of natural, as well as artificial fibers, the softer yarns accompany the finer filament deniers and the harsher and stiffer products the higher filament deniers.

A further description of the nature of the crimp possessed by the fibers and the conditions under which it persists will serve to illustrate its inherent and permanent character. The most simple, direct test illustrating the character of the fibers consists in taking preferably a single dry finished filament several inches long and thoroughly wetting it with water or by carefully drawing it several times between the moistened lips so as to wet it out. While wet, the filament may be given a substantial amount of stretch over and above that required to straighten out the crimp. If the experiment is performed by repeatedly drawing the filament between the moistened lips to wet it, a slight pressure of the lips while drawing the filament through will straighten out the crimp and serve to impart additional stretch thereto. Immediately after wetting has been completed the fiber is held up at one end (the other end being free) and viewed as it dries, preferably against a. black background in good light. The drying will be accomplished at room temperature in a minute or so. As the fiber dries it will be noted that it begins to twist, curl, and shorten in length and to take on a very decidedly crimpy and sometimes a spiral crimpy character, so that by the time its drying is completed it has greatly contracted from its original wet length and is now curled and irregular and its general form corresponds to that which it possessed immediately after being spun and coagulated. The same fiber may be again similarly wetted and dried, or wetted, stretched and dried, and this may be still further repeated on the same fiber with spontaneous contraction and crimping occurring. Whether the fiber in this experiment assumes a very large or lesser number of crimps per inch will depend primarily on .whether the yarn was initially coagulated to give a large or small number of crimps per inch.

To still further illustrate the inherent, permanent crimpy character of the fibers, one way take a single fiber or a small bundle thereof, thoroughly wet it in water, and thereafter stretch the wet filaments at least 10% or, if desired, even much more. The stretching mentioned here refers to a stretch over and above that required to just remove the crimps from the filaments. While still in this set stretched and straightened condition, and while under tenson, the filaments are thus completely dried, without permitting them to contract. The filaments are then removed from the device which has held them straight during drying. At this stage they are, of course, substantially straight. They are then thoroughly wet out with water and, after removal from the water, are held at one end and allowed to dry freely in the air again. In spite of the fact that the filaments had been wet stretched and dried in a straightened and stretched condition, they will still again assume their crimpy shape when allowed to dry freely. Thus, while the filaments or threads may have been dried to a straightened shape at some stage in their processing, or in their conditions of use, their crimpy form can easily be restored by merely rewetting with water, followed by drying conditions which permit them freedom to contract, and so assume their natural crimpy shape. The process described above may be further repeated without destroying the inherent and permanent character of the crimp.

By way of example, which in no way limits the scope of the invention, a table is appended herewith illustrating the crimp recovery characteristics of one typical fiber product after it has been wet in water and stretched to varying amounts over and above that necessary to remove the crimp, followed by free drying whereby the yarn and/or filaments are free to contract to their fullest extent. Ten centimeter lengths of approximately 300 denier 40 filament crimpy thread were immersed in water several minutes at 20 (3., whereby the yarn was thoroughly wet out with consequent spontaneous elongation to the extent given in column 2 of the table below. The lengths of thread were then positively stretched to the length given in column 3. This amount of stretching was not only suflicient to completely remove crimps, but to impart substantial additional stretch to the thread itself. The threads were then removed from the water, blotted to remove excess adhering liquor, and suspended freely in the air and allowed to completely dr in gently moving air currents. The figures given in column 4 indicate the final thread length.

iitinilt'ii Length after Length gth of dry crimpy Wetting ut n pp yi g thread alter thread water at 20 C. stretch drying Om. Cm, Cm Cm 10 i9. 6 25 6 10 19. 6 29 9 9 10 19. 6 32 3 4 10 19.6 30 3 10 i9. 6 35 10.3

It is to be noted that the thread undergoes practically complete recovery to its original length and that this result obtains, even with the higher amounts of stretch given to the sample. In one case a 10 cm. length of original thread was wet out and stretched to 35 cm., but on drying freely contracted with regain of crimp to within 10% of its original length.

In another set of tests, 10 cm. lengths of dry crimpy yarn were stretched in the dry state to varying amounts in addition to that required to completely remove the crimps, but not sufficient to break the yarn or an substantial number of filaments thereof. In the case of the particular sample employed, a 10 cm. length was stretched to 19 cm., which stretch was that required to just remove the crimps. While still in the dry state, this sample was given an additional stretch of 3 cm., whereby its length was increased to 22 cm. and the filaments all lay substantially straight. This sample, while still being. maintained at 22 cm., was wet with water and dried while maintaining its length at 22 cm. At this point, the filaments still lay substantially perfectly straight and parallel. While it might be expected that such a treatment had destroyed the crimping power of the fiber, this is not the case, since when this length of thread is again thoroughly wet by water and allowed to dry in a freely suspended state it will do so with marked contraction and development of crimps to the extent that its final dried length was 12.4 cm. The filaments composing this yarn still presented a highly crimpy appearance.

In order to still further exemplify the nature of the crimp which is inherent'in the fibers, the following experiment may be cited. A considerable length of approximately 300 denier 40 filament crimpy yarn was spun according to the process and after leaving the coagulating bath was wound up on a perforated bobbin. The bobbin containing the unre'generated yarn was removed from the spinning machine and immersed in an acid regenerating bath. The yarn, while still on the same bobbin, was further. processed by washing free from acid, desulfurlng in hot sodium carbonate solution, followed by a thorough washing. Thereafter the yarn, while still on the bobbin, was dried by means of heated air. It was found after drying that the filaments and the threads composed thereof lay on the bobbin in substantially straight form, having lost all the natural crimp as spun due to the fact that the yarn had been dried on a rigid support. The straightthreads were then wound onto a small wooden spool under slight winding tension and thereafter this spool was placed in an autoclave for one-half hour and heated in the presence of lbs. steam pressure, following which the bobbin was removed from the autoclave. On unwinding the threads from the bobbin itwas found that the product possessed the appearance of ordinary straight filament rayon, no indication of crimps being apparent. It might be supposed that this treatment had destroyed the tendency of the yarn to crimp, for not only was the initial drying of the yarn on a rigid support carried out so as to remove all the crimps, but, in addition, the yarn in this'straight form was further steamed under high pressure, which treatment has heretofore been used to set regenerated cellulose structures in new and various shapes. However, after removing the threads from the bobbin on which they had been steamed straight and completely wetting out these threads with water, followed by drying in a freely suspended condition, it was found that after drying they had spontaneously assumed the usual highly crimpy form characteristic of the products and were substantially indistinguishable from yarns of the process which had not undergone such treatment.

The above examples serve to illustrate the inherent tendency of the fibers to regain their crimpy form after being given a variety of treatments which would be expected to destroy the crimp. These tests are purely exemplary and do not in any way limit the invention. The threads or fibers may be submitted to still other conditions not included in the above tests and still regain their crimpy form after wetting and free drying. Wetting with water prior to drying in a free condition has been mentioned and in this particular, it is to be understood that use may be made of both cold and hot water, or even boiling water. Indeed, hot or boiling water will usually be more effective in the process of restoring the fibers to their crimpy form than cold water. Many prior-art curly or kinky fibers, on the other hand, after treating with very hot or boiling water lose or tend to lose their shape and tend to revert back to the straight condition in -which they were spun.

The crimpy character of the product is such that it will, furthermore, persist after treatment by" various chemical agents such as soaps and other detergents, dilute acids, dilute alkalies and the like such as may be commonly encountered in the dyeing and finishing industry.

The product, for instance, may be submitted to the action of caustic soda solution of concentrations up to several percent or even more, at room temperatures or hot, without substantially affecting the crimpy character of the product when it is thereafter washed free from treating liquor and finished. and dried as hereinbefore described.

The products of the invention are suitable for a wide variety of uses to obtain special effects in fabrics, which uses and effects have hitherto been impossible to achieve with the inherently straight artificial fibers of the prior art. It may be used in the textile industry either as yarn composed of continuous crimpy filaments, or the fibers maybe cut up into'staple lengths and processed thereafter in this form, either alone or admixed with other fibers. It is often advantageous, however, in many cases and in the interest of economy to employ the product in the form of continuous filament threads and achieve many novel fabric effects. The product is suitable for both knitting and weaving a great variety of fabrics. Such fabrics will possess much greater body and loft than when constructed from straight filament rayons or staple of the prior art. The product is particularly useful in the formation of pile fabrics in that the wildness of the filaments results in a unique character of the pile similar to that of a pile constructed from natural wool. Due to the added covering power, bulk, and occluded air spaces in fabrics constructed from .the fibers, they show an improved warmth characteristic over similar fabrics constructed from prior art artificial fibers. In general, fabrics so constructed will possess a somewhat worsted or woolly character and feel as compared to the thin, sleek, and rather cool character of fabrics constructed from prior art straight filament yarns. Repeated observations carried out on fabrics constructed from the products of the invention show that the crimpy character of the filaments carries over into the finished cloth and is to a large degree responsible for the special effects obtained therein. Furthermore, such fabrics may be submitted to wearing and repeated washing and drying without substantial loss of its unique characteristics. This results from the permanent and inherent character of the crimp imparted to the individual fiber by means of the invention.

It will be apparent from the above description of the process and products of the present invention that they are capable of great extension and modification without departing from the nature and spirit of the invention and that one skilled in the art when taught by this invention may produce a great variety of fiber products showing characteristics and properties which have been hitherto unachieved in the art of artificial fibers. It is, therefore, to be understood that the invention is not tobe limited except as set forth in the appended claims.

We claim:

1. The process of directly spinning crimpy filaments which comprises extruding viscose, in the form of filaments, into a setting bath which has a sutliciently rapid coagulating action. relative to any regenerating action thereof, to completely coagulate said filaments prior to any substantial regeneration thereof, drawing said filaments from the point where they are extruded into the bath, the velocity of extrusion being at least four times the velocity of draw-off.

2. The process of directly spinning crimpy filaments which comprises extruding viscose, in the form of filaments, into a setting bath having a coagulating and regenerating action on said filaments, said bath having a sufficiently rapid coagulating action, relative to the regenerating action thereof, to completely coagulate said fila-' ments prior to any substantial regeneration thereof, drawing said filaments from the point where they are extruded into the bath, the velocity of extrusion being at least four times the velocity of draw-off.

3. The process of directly spinning crimpy filaments which comprises extruding viscose, in the form of filaments, into a setting bath having a coagulating but no regenerating action on said filaments, drawing said filaments from the point where they are extruded into the bath, the velocity of extrusion being at least four times the velocity of draw-off, and regenerating said filaments.

4. The process of directly spinning crimpy filaments which comprises extruding viscose, in the form of filaments, into a setting bath comprising an ammonium salt solution, which bath has a sufficiently rapid coagulating action, relative to any regenerating action thereof, to completely coagulate said filaments prior to any substantial regeneration thereof, drawing said filaments from the point where they are extruded into the bath, the velocity of extrusion being at least four times the velocity of draw-off.

5. The process of directly spinning crimpy filaments which comprises extruding viscose, in the form of filaments, into a setting bath comprising an ammonium sulfate solution, which bath has a sufliciently rapid coagulating action, relative to any regenerating action thereof, to completely coagulate said filaments prior to any substantial regeneration thereof, drawing said filaments from the point where they are extruded into the bath, the velocity of extrusion being at least four times the velocity of draw-01f.

6. The process of directly spinning crimpy filaments which comprises extruding viscose, in the form of filaments, into a setting bath comprising a solution of ammonium sulfate and sodium sulfate, which bath has a sumciently rapid coagulating action, relative to any regenerating action thereof, to completely coagulate said filaments prior to any substantial regeneration thereof, drawing said filaments from the point where they are extruded into the bath, the velocity of extrusion being at least four times the velocity of draw-ofl.

7. The process of directly spinning crimpy filaments which comprises extruding viscose, in the form of filaments, into a setting bath comprising an acid, which bath has a sufilciently rapid coagulating action, relative to any regenerating action thereof, to completely coagulate said filaments prior to any substantial regeneration thereof, drawing said filaments from the point where they are extruded into the bath, the velocity of extrusion being at least four times the velocity of draw-off.

8. The process of directly spinning crimpy filaments which comprises extruding viscose, in the form of filaments, into a setting bath which has a sufllciently rapid coagulating action, relative to any regenerating action thereof, to completely coagulate. said filaments prior to any substantial regeneration thereof, drawing said filaments from the point where they are extruded into the bath, the velocity of extrusion being at least four times the velocity of draw-off, and stretching the crimpy filaments while in a wet state.

9. The process of directly spinning crimpy filaments which comprises extruding viscose, in the form of filaments, into a setting bath having a coagulating and regenerating action on said filaments, said bath having a sufiiciently rapid coagulating action, relative to the regenerating action thereof, to completely coagulate said filaments prior to any substantial regeneration thereof, drawing said filaments from the point where they are extruded into the bath, the velocity of extrusion being at least four times the velocity of draw-off, and stretching the crimpy filaments while in a wet state.

10. The process of directly spinning crimpy filaments which comprises extruding viscose, in the form of filaments, into a setting bath having a coagulating but no regenerating action on said filaments, drawing said filaments from the point where they are extruded into the bath, the velocity of extrusion being at least four times the velocity of draw-oil, regenerating said filaments and stretching the crimpy filaments while in a wet state.

11. The process of directly spinning crimpy filaments which comprises extruding viscose, in the form of filaments, into a setting bath comprising an ammonium salt solution, which bath has a sufficiently rapid coagulating action, relative to any regenerating action thereof, to completely coagulate said filaments prior to any substantial regeneration thereof, drawing said filaments from the point where they are extruded into the bath, the velocity of extrusion being at least four times the velocity of draw-off, and stretching the crimpy filaments while in a wet state.

12. The process of directly spinning crimpy filaments which comprises extruding viscose, in the form of filaments, into a setting bath comprising an ammonium sulfate solution, which bath has a sufliciently rapid coagulating action, relative to any regenerating action thereof, to completely coagulate said filaments prior to any substantial regeneration thereof, drawing said filaments from the point where they are extruded into the bath, the velocity of extrusion being at least four times the velocity of draw-oil, and stretching the crimpy filaments while in a wet state.

13. A yarn, having a strength of at least .5 gram per denier, comprising substantially noncrenulated regenerated cellulose filaments, the molecules of which have a substantially random distribution throughout the body thereof, said filaments having from 10 to 50 permanent crimps per inch, said crimps lying in three dimensions, the crimps of said filaments being out of phase with each other.

14. A substantially non-crenulated regenerated cellulose filament, having a strength of at least 0.5 gram per denier, said filament having permanent crimps, said crimps lying, at random, in three dimensions.

15. A yarn, having a strength of at least 0.5 gram per denier, comprising substantially noncrenulated regenerated cellulose filaments, said filaments having permanent crimps, said crimps lying, at random, in three dimensions.

16. A substantially non-crenulated regenerated cellulose filament, having a strength of at least 0.5 gram per denier, the molecules of which have a. substantially random distribution throughout the body thereof, said filament having permanent crimps, said crimps lying, at random, in three dimensions.

17. A yarn, having a. strength of at least 0.5 gram per denier, comprising substantially noncrenulated regenerated cellulose filaments, the

molecules of which have a. substantially random distribution throughout the body thereof, said filaments having permanent crimps, said crimps lying, at random, in three dimensions.

WILLIAM HALE CHARCH. WILLIAM FREDERICK UNDER-WOOD.

CERTIFICATE OF CORRECTION. Patent No. 2,2u9,7l+ ,July 22, 19in.

WILLIAM HALE CHARGE, ET AL.

It is hereby certified-that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, line 1414., for the word "is" read --as--; page 5, second column, line 58, for "of" read --by--; page 1;, first column, line 5-6, for"depending read -dee'pen ?.ng; same page, second column, line 58, for the word "centrifuging" read centr1mgally; page 6 second column, line 10-11, for "threaded" read -created; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office. I

Signed and sealed this 7th day of October, A. D. 191 1;

Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

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