US3388547A - Method for producing wool-like synthetic yarn - Google Patents

Description

June 18, 1968 sumo KOGA ET AL 3,388,547

METHOD FOR PRODUCING WOOL-LIKE SYNTHETIC YARN Filed Aug. 18, 1964 3 Sheets-Sheet 1 5ioLLeN YARN 1000 ,A- YARN OF THE INVENTION CONVENTIONAL YA R N o 5 N) I5 21325505540 ELONGATION 0 CONVENTIONAL YARN IOO 1 fill -YARN OF THE I, INVENTION H WoOLLEN YARN I v 4.6 ,flM Attorney;

June 18, 1968 $H|Ro KOGA ET AL 3,388,547

METHOD FOR PRODUCING WOOL-LIKE SYNTHETIC YARN 3 Sheets-Sheet 2 Filed Aug. 18, 1964 B w z 4 M A tlo fneyg June 18, 1968 s o b ET AL 3,388,547

METHOD FOR PRODUCING WOOL-LIKE SYNTHETIC YARN Filed Aug. 18, 1964 5 Sheets-Sheet 3 I v H rney;

Patented June 18, 1968 3,388,547 METHOD FOR PRODUCING WOOL-LIKE SYNTHETIC YARN Shire Koga, Toyonaka, and Yoshiaki Miyagawa, Sumiyoshi-ku, Gsaka, Japan, assignors to Toyo Boseki Kahushiki Kaisha, Osaka, .Iapan Filed Aug. 18, 1964, Ser. No. 390,783 Uaims. (Cl. 57-157) This invention relates to an improvement of a method for producing wool-like yarn of thermoplastic fiber.

It is well known to produce a bulky yarn by blending high-shrinking fibers and low or non-shrinking fibers and spinning the same into yarn. The spun yarn or its prodnot such as plied yarn, woven or knitted fabrics is then dry or wet heat treated in a relaxed state so that the high-shrinking fibers are shrunk while the low or nonshrinking fibers (which are sometimes called regular fibers) are relaxed with a result that the yarn or its product is rendered bulky.

We have found that the bulky product produced by the conventional method which is characterized by that the heat treatment is conducted always after the fibers have been spun into yarn has various drawbacks that the bulkiness is not fully satisfactory, the product is hard and not good in hand as compared with those of wool. Furthermore the conventional bulky yarn is not fully satisfactory in its strength, elasticity, etc.

It has been found that when a thermally shrinking and heat-set treatment is conducted prior to spinning in sharp contrast to the conventional method the above mentioned and other drawbacks seen in the product produced by the conventional methods are overcome.

Thus, briefly speaking, the method of this invention comprises blending high shrinking thermoplastic synthetic fibers and low shrinking thermoplastic synthetic fibers, heat treating the same in the form of sliver, untwisted strand or roving prior to spinning to produce crimps therein, setting the crimps so produced, and then spinning into yarn.

The invention will be described in more detail as follows by referring to the accompanying drawings wherein:

FIG. 1 is a load-elongation curve of a wool-like acrylic bulky yarn of this invention as compared with conventional acrylic bulky yarn and extra-fine genuine Woolen yarn,

FIG. 2 is a diagram showing the initial load-elongation and final recovery curves of the three yarns of FIG. 1 as they are subjected to a predetermined load over several cycles,

FIG. 3a is a schematic side elevation of conventional bulky yarn,

FIG. 3b is an enlarged replica thereof,

FIG. 4a is a schematic side elevation of a wool-like yarn of this invention,

FIG. 4b is an enlarged replica thereof,

FIG. 5a is a schematic section of a top of silver to be used in carrying out the shrinking operation, the sliver being taken up on a bobbin, and

FIG. 5b is a perspective view of the sliver after the bobbin has been removed before the heat-treatment.

The conventional staple bulky yarn is manufactured by blending suitable amounts of a short staple fiber (bulky fiber) which has been rendered thermally shrinkable by about to 35% by thermal stretch and a short staple of non-shrinking or low shrinking fiber (referred to as regular fiber), spinning the same into yarn, and then shrinking the bulky fiber in the form of single yarn, plied yarn, woven or knitted fabrics by means of a heat treatment in hot water, steam or hot air while relaxing the regular fiber, so as to produce a bulkiness in the yarn or its product.

The mechanism by which such a bulkiness can be obtained will now be explained in detail. When a spun yarn consisting of a bulky fiber and a regular fiber which are mixed with each other is treated at a temperature which is determined by the types of the shrinking fibers and the crimping conditions in such a manner that the yarn is allowed to shrink lengthwise with respect to the length of fiber, the bulky fiber alone shrinks and the regular fiber lying near the surface of the yarn forms loose bulges as shown by the numeral 1 in FIGS. 3a and 3b. However, the regular fiber forming the core of the yarn is compacted upon shrinking of the bulky yarn so that along with the bulky fiber, the regular fiber forms a-core as shown by the numeral 2 in FIGS. 3a and 3b. This core 2 considerably detracts from the potential bulk and, being hard, affects the hand of the yarn adversely. Because the heat-insulating properties of a yarn owes much to the amount of air trapped in the interfiber spaces, a core made up of such compacted fibers is obviously detrimental to the insulating properties of the yarn when it is made up into clothing. This type of bulky yarn is lacking considerably in elasticity and, also, in strength. As illustrated in FIG. 3a, a closer scrutiny of each fiber would reveal that a comparatively small number of fibers form relatively large bulges and, unlike wool, there cannot be observed fine crimps. If the conventional bulky yarn is subjected to a tensile strength test, it will be found that only the fiber forming the core contributes to the tensile srength which is as low as about percent as compared with the strength of a spun yarn composed entirely of a regular fiber.

This invention is concerned with a method of producing a bulky yarn which is similar to a woolen yarn, said bulky yarn being composed of bulky fiber and regular fiber, characterized in that each of the component fibers has fine irregular crimps and yet all the fibers contribute to the bulk of the yarn. The crimp obtainable by this invention is not of conventional method obtained by twisting, stutter-box, and other methods which are usually employed for continuous synthetic fibers such as nylon and polyester, and it does not utilize the latent shrinking properties of the fiber itself as it is the case with the socalled biocomponent yarn.

The important feature of the method of this invention is to conduct the crimp-producting treatment while the fiber is in the form of a spinning intermediate, e.-g. sliver, top roving or untwisted strand in the state in which the fiber can freely shrink lengthwise which the not bulky fiber alone is allowed to shrink so that, as the bulky fiber shrinks, the bulky fiber and regular fiber restrict one another to produce fine wool-like crimps in all the component fibers. After or simultaneously with the crimp formation these crimps are thermally set, and then the sliver, top or roving is spun into yarn through the usual spinning processes. The final product, then, is quite similar to woolen yarn.

While the mechanism by which crimps are formed in all the component fibers has not yet been completely elucidated, the following model may be tentatively proposed to explain it. It may be visualized that a single regular fiber is surrounded by bulky fibers and there is a proper pressure distribution among all the fibers, and when the bulky fiber is caused to shrink, the regular fiber Will not shrink and, therefore, delicate crimps are produced in the regular fiber just as if the fibers were forced into a stuffer box. When such a model takes place in various parts of the fiber aggregate, the fibers tend to interfere one another so that delicate and fine crimps are also produced in the bulky fiber.

The degree of shrinkage of the high-shrinking fiber (sometimes referred to as bulky fiber) which would give a satisfactory crimp ranges from about 15 to 35 percent.

To measure the rate or degree of shrinkage, the length of the fiber is measured under a load of 100 mg. per denier, and, then, after the fiber is treated in boiling water for minutes, the length of the fiber is measured again under the same load of 100 mg. per denier. Thus, the rate of shrinkage .is calculated from the results obtained before and after the hot-water treatment.

The high-shrinking fiber may be obtained by cutting a thermally stretched tow, or by processing a non-shrinking tow by a turbo-stapler or similar apparatus wherein the tow is stretched and cut into staples. The non-shrinking or low-shrinking fiber may be obtained by cutting a nonshrinking or low-shrinking tow or by processing the same by means of a turbo-stapler or other similar devices and, then, heat-treating it in a relaxed state. In this connection, the rate of shrinkage of the low-shrinking fiber is preferably as small as possible. That is to say, it is preferable that the difference in the rates of thermal shrinkage between the two dissimilar fibers is as great as possible.

The mixing ratio of the high-shrinking and nonor low-shrinking fibers that gives satisfactory crimps is to 85 percent in terms of the high-shrinking fiber in the fiber blend. When slivers are mixed the amount of doublings is about 200 or more in order to insure that the relative positions of the high-shrinking and low-shrinking fibers may be such that they easily develop crimps.

It should be understood that the term shrinking as used before the term fiber means that the fiber will shrink when it is heat treated in a relaxed state.

In case the high-shrinking fiber is mixed with the lowshrinking fiber at or before the carding step, they are blended together satisfactorily. However, in order to array or orient the fibers it is preferable to draft them once or twice subsequent to the carding step.

The denier number of the raw materials or fibers to be used should be determined according to the count of the desired yarn, the type of the final product to be manufactured, and other factors, while the length of fiber depends on the type of spinning machinery to be used, the count of the yarn to be spun, and the type of the final product to be manufactured. Generally speaking, a denier of 1.5-15 and a fiber length of 35-200 mm. would be found satisfactory. The suitable degree of restriction to which the fiber is subjected (fiber density) when it is heat-treated in order to produce crimps 0.05-0.15 g./crr1. for sliver, or the twist coefiicient of 2-15 for roving (assuming the twist coefiicient is K, the number of twists per meter is T, the count of the yarn as expressed in meters is N, T :W

The conditions of said heat-treatment which, would give satisfactory crimps vary with the type and history of the fiber used. The heat-treatment has a dual purpose. One is to shrink the high-shrinking fiber to produce crimps and the other is to thermally set the crimps so produced, although the shrinking heat treatment and the thermal set of the crimps may be carried out separately. The treating temperature required to produce such. a crimp by shrinking the high-shrinking fiber is determined by the intrinsic properties of the fiber and the conditions under which high-shrinking properties have been preliminarily imparted to the fiber. The temperature required to set the crimp so produced is determined by the intrinsic properties and histories of both the high-shrinking and lowshrinking fibers.

These two efiects of heat treatment may be obtained by various methods. For example, when the development of such shrinkage and crimps is efiected in hot Water, the crimp may be set while the fiber is subsequently dried, and when the shrinking and crimping are effected in steam at atmospheric pressure, the crimp may be set at the immediate following step by means of a hot air or highpressure steam. In case the fiber is treated in saturated steam at high pressure, the crimping and thermal setting are concurrently effected in one operation. The heatsetting by any of the above-mentioned methods renders the crimp sufiiciently durable so that the drafting operation to be conducted at some step or other in the spinning processes will not liquidate the crimp, nor will the dyeing process after spinning cause the crimp to disappear. Moreover, this crimp, once produced as above, is not lost even when the apparel or clothing made of such a bulky yarn is repeatedly worn or laundered and the apparel retains its bulkiness over a long time of use.

The conditions under which the crimp is to be beatset may vary rather widely according to the history of the fibers, and the upper limits of temperature are determined by the intrinsic thermal characteristic of the fibers. However, the following values should prove helpful with respect to the principal types of synthetic fiber available commercially today.

TABLE 1 Crimp-setting temperatures suitable for various fibers Fiber Dry hot air, C. Saturated steam, C.

140-160 -135 150-185 -100 -100 130-100 Polypropylene 130-145 110-135 This invention will be described in further detail by way of the following examples.

EXAMPLE 1 shrinking fiber was well mixed with the regular fiber.

forming three-dimensional helics and the fibers were held in this state by the frictional forces acting among the individual staples. The roving was produced by mixing the two different fibers and processing the same by a Worsted spinning method to prepare a roving which has an adequate number of twist.

The roving was made into a hank and, while keeping the same not to restrict the lengthwise shrinkage, it was held in saturated steam at 130 C. for 10 minutes, whereupon the high-shrinking fiber in the roving was shrunk. At the same time crimps were produced. At this moment, due to the frictional forces acting among the individual fibers and the changes in length of the high shrinking fiber, very delicate and fine crimps are produced in both the bulky and regular fibers throughout the roving. Furthermore, since the individual fibers remain three-dimensionally intertwined when the above-mentioned crimps are formed, the crimps bear a close resemblance to the woolen fiber which has irregular three-dimensional crimps, and the yarn spun from such a roving having had its crimps heat-set differs entirely from the conventional bulky spun yarns in both appearance and characteristics.

It is also possible to prepare a roving by reducing the fiber length and processing the fiber by the cotton spinning system. In this case, the blending of the high-shrinking and regular fibers can be more conveniently carried out in the state of stock. To heat-treat the roving a bank of roving may be employed as in the above example, or, alternatively, the heat-treatment may be carried out after the roving is wound on a bobbin of a comparatively large diameter and, then, the bobbin is slipped out. Alternatively, a core which is compressible by external forces may be employed and, in this case, the roving with the core may be put into a heat-treating apparatus. Besides the method of this example in which the development and heat-setting of crimps is effected in high-pressure saturated steam in one operation, the heat-setting of the fiber may also be effected by treating the same with high-temperature saturated vapor or with dry, hot air after the crimps have been developed by means of hot water or steam at 80-130 C. The wool-like crimps which have thus been thermally set, are highly stable to the drafting operation which is conducted at a later stage of the spinning process and, also, is virtually impervious to the external forces to which the yarn is subsequently subjected when it is dyed, washed or dried.

The characteristics of the crimped fiber and bulky yarn obtainable by the method described in this example are summarized in Tables 2 and 3. It will be apparent from these tables that as compared with the crimp produced. mechanically by crimper box, the crimping characteristics of our fiber are considerably superior and the crimps are not lost when the fiber is drafted or/and immersed in hot water.

TABLE 2.-A COMPARISON OF THE CRIMPS OBTAINED BY TI-IE ABOVE EXAMPLE OF THE INVENTION WITH CONVENTIONAL MECHANICAL CRIMPS Exlan 6d, 102 Exlan 6d, Fiber mm. mec anical crimps of this crimps example Number of crimps/25.4 mm 12 25 Degree of crimping (percent) 4. 7 13. 4 Elasticity (percent) 70. 4 70. 5 Number of crimps/25.4 mm. after hot-water treat, 100 C./ min 5 22 TABLE 3.-THE CRIMP CHARACTERISTICS OF THE PROD- UCI OF THIS EXAMPLE 1 AT VARIOUS STAGES Immediately After Alter Alter alter crimp draftspinyarn setting ing ning dyeing Number of crinips/25.4 mm. 22. 3 20. 2 23. 5 Degree of crimping (percent). 13. 4 13. 2 12. 2 14.0 Elasticity (percent) 76. 5 79. 4 77.3 77.5

Elasticity After the above procedure, if the second-mentioned load is reduced to the initial load and, then, the length of the fiber is C, the elasticity of crimp is calculated by the following equation:

Degree of crimping;= X 100 (percent) Elasticity of crimp=g j l00 (percent) The load-elongation curve of the yarn of this example and its recovery characteristics as observed when a predetermined load is applied repeatedly are shown in FIGS. 1 and 2, respectively. These curves show that the yarn obtained in this example bears a close resemblance to a woolen yarn. Since the yarn of this example stretches itself greatly under a nominal load and each of the coin ponent fibers contributes to the tensile strength of the yarn, its breaking strength is about higher than the conventional bulky yarn. The specifications of the yarns used in the tests resulted in FIGS. 1 and 2 are as follows:

WOOL-LIKE YARN MADE BY THIS INVENTION Count 2/285. Twist:

Single 300 twists/m. Ply 220twists/m. Dyeing Hank dyed after spinning.

CONVENTIONAL BULKY YARN Fiber Exlan (acrylic fiber) 6 d., 100%.

Count 2/365; (2/28s alter hank dyeing).

Twist:

Single 2l0twists/m.

Ply 220twists/m. Dyeing Hank dyed after spinning.

FINE \VOOL KNITTING YARN Count 2/18s. Twist:

Single 270 twists/m.

Ply 230 twists/m. Dyeing Top dyed.

When the conventional bulky yarn of acrylic fiber or a product made up of the same yarn is dyed or laundered at a high temperature beyond C., the loops of the regular fiber extruding out of the yarn body are sup pressed or retrenched, giving rise to the so-called leaning out etfect.

The acrylic fiber composed of two dissimilar components (known as bicomponent fiber) is described, for example, in Japanese patent publication Nos. 19,214/1961 and 10,860/1962, and is known to develop wool-like crimps. However, if a yarn is made entirely of this acrylic bicomponent fiber or such a yarn is made into a product, and the resulting yarn or product is dyed or washed at a temperature of higher than 80 C. and hung to dry, the crimps will be substantially lost and the yarn becomes slim and loses much of its elasticity. Therefore, in washing and drying such a product, special care must be paid to the washing temperature and the drying method. Fur thermore, due to the very nature of production, the cost of the bicomponent fiber is higher than that of the regular acrylic fiber.

The spun yarn of this example and the product made up of the same has no leaning out tendency unlike the conventional bulky spun yarn, but rather has a tendency to produce additional crimps upon washing and drying and retain their original dimensions even after they are worn or/ and laundered. As shown in the following table by way of example, the results of a use test conducted over 2 months (washed 5 times) with an underwear made of the spun yarn of this example have confirmed the excellent characteristics and good dimensional stability of the yarn.

TABLE 4.RESISTANCE TO WASHING TO A KNITTED WEAR MADE OF THE BULKY YARN OF THIS INVENTION Note-Tire figures given in the above table represent the percents ge relative to the initial length marked on the knit.

The crimps developed and heat-set in the above manner are very delicate fine and three-dimensional, with the result that, as shown in FIGS. 4a and 4b, the final bulky yarn has a good bulkiness, besides being excellent in both elasticity and strength. The yarn manufactured in this manner is an ideal bulky yarn which bears a close resemblance to a woolen yarn and is entirely different in characteristics including appearance and hand from the conventional bulky yarn which is produced while the fiber is held in a restricted state by its own twist.

When the wool-like bulky yarn of this invention is compared with the conventional bulky yarn, the bulk of the former is about 16% greater than that of the latter. Since the conventional short-staple bulky yarn is heat treated for the crimp development while the bulky and regular fibers are twisted strongly into a spun yarn (the fiber density of the hank is 0.20.3 g./cm. the lesser number of regular fibers lying near the surface of the yarn are loosened and develop a bulk. In contract, the bulk spun yarn of this invention is characterized in that, as shown in FIG. 4b, all the individual fibers forming the yarn have delicate crimps resembling those of wool and the yarn itself is as elastic as woolen yarns, with its surface being smooth and attractive. Furthermore, the knitted product of this yarn has good elasticity and the appearance of the knit structure is exceptionally clear and aesthetic. If the spun yarn of this example is used as filling of a fabric and the strain caused in the fillings by weaving is removed by treatment with hot water or dyeing, the fabric assumes a satisfactory degree of elasticity in the weftwise direction. In this manner, a so-called stretch fabric can be obtained. For example, the weaving conditons used in the manufacture of such fabric are as follows:

the fillings by weaving is removed by hot-water treatment or dyeing.

The fabric woven under the above-mentioned conditions has a weftwise elasticity and shows a satisfactory recovery when stretched by 35%.

EXAMPLE 2 This example shows the application of the shrinking heat treatment of this invention to the top as it is referred to in the art of worsted spinning. A sliver prepared from 30% of S-denier acrylic fiber (trademark Exlan) having a hot-water shrinkage of 28% and having an average staple length of 102 mm. and 70% of a regular fiber made of a 5-denier acrylic fiber (trademark Exlan) cut to an average fiber (staple) length of 102 mm. was wound on a wooden. bobbin as shown in FIG. 5a. The weight of the sliver was g./m. and the top was 40 cm. in diameter and cm. in length, weighing 3 kg. The density of the top was 0.08 g./cm.

After the bobbin was slipped out, the top of a hollow cylindrical shape (see FIG. 5b) was treated in saturated steam at 130 C., whereby the bulky fiber was shrunk to produce a crimp therein and the crimp set at the same time.

The sliver in the top that remains after the wooden bobbin is removed, is free to shrink lengthwise and as it has been wound to the above-mentioned fiber density, the bulky and regular fibers in the sliver are suitably pressed against each other in a well mixed state. If the sliver is heat-treated in this state, very delicate and fine crimps are formed in every fiber as described in EX- ample 1.

As for the crimping and heat-setting methods, those methods which are described in Example 1 may also be employed in respect of a top.

The procedure of this Example 2 is preferable when this invention is applied to mass production. It has been found that some conditions would affect the results when the invention is carried out in a manner as in Example 2. From the fact that when bulky and regular fibers are mixed nd treated to produce and heat-set crimps, the regular fiber is more pronouncedly crimped than the bulky fiber and, also, from the fact that the ratio of the bulky yarn to the total fiber content has a bearing on the shrinking properties of the yarn, for instance, the crimping characteristics of the sliver after it is treated as above vary with the relative amount of the bulky and regular fibers. Thus, there are the optimum blending proportion that 8 would produce the best possible crimps. When the blending ratio has been varied the following results have been obtained.

TABLE 5.BLENDING RATIOS AND CRIMPING CHARACTERISTICS Ratio of bulky Number of Degree of fiber (percent) mumps/25.4 mm. crimping (percent) Furthermore, it has been found that the degree of restriction (-fiber density) to which the sliver is subjected also atfects the crimping characteristics. The greater the restrictive force, the crimp will be finer, but if the force exceeds a certain limit, the sliver is prevented from shrinking to a satisfactory extent so that it does not only result in uneven crimping, but the whole spinning process becomes difficult. Table 6 shows the results of our experiments wherein the procedure of Example 2 was repeated with tops of various fiber densities.

TABLE 6.--RELATIONSHIP BETWEEN THE FIBER DEN- THE TOP AND THE CRIMPING CHARACTER- Top density Number of Remarks -l fi) crimps/25.4 mm.

25. 7 Slightly ditticult to spin.

It will be apparent from the above table that the optimum fiber density lies somewhere in the neighborhood of 0.08 g./cm.

It has also been found that there is a certain relationship between the temperature at which the sliver is crimped and the characteristics of the resulting crimp. Since the same bulky fiber could shrink to a varying degree depending upon the particular temperature, the characteristics of the resulting crimp would also vary. For example, the rates of shrinkage of an acrylic bulky fiber (trademark Exlan) under various conditions are as follows.

Table 7 shows the results of our experiments in which the crimping treatment of the top of Example 2 was carried out at various steam temperatures. It will be apparent that as the temperature increases, the characteristics of the resulting crimp is improved.

TABLE 7 Number of Degree of Crimp Steam temp., C. turnips/25.4 crimping recovery mm. (percent) (percent) The sliver treated and crimp-developed in the above manner may be made into yarns of various twists and counts by the conventional spinning method, according to the end use. It is also possible to mix the above mentioned sliver processed according to this invention with sliver of other similar or dissimilar types of fiber to get another kind of yarn. For instance, 70% of the crimped slivers prepared as above may be blended with 30% of conventional bulky slivers by the usual spinning method to make a bulky yarn. The yarn manufactured in this manner is an excellent bulky yarn which not only has characteristics not found in the conventional bulk yarn, but even when dyed or otherwise treated, shows no signs of leaning out (the tendency to get slimmer) which is acknowledged to be a major drawback of the conventional bulky yarn. In this bulky yarn the low-shrinkage fiber corresponding to the regular fiber of a conventional bulky yarn is composed of crimped fiber produced by this invention. If the yarn is made into a knit, the resulting structure of a knit is beautifully distinct as contrasted to the dull of a comparable knit of the conventional bulky yarn. Moreover, due to the unique crimps which are not found in the conventional bulky yarn, the hand of such a knit is far superior to that of a knit of the conventional bulky yarn.

The crimped sliver of this invention may be mixed with a different kind of fiber. As the fiber to be mixed with the sliver of this invention, use may be made of any and all fibers, e.g. wool, cotton, rayon, nylon, polyester-type synthetic fiber, polypropylene fiber, etc. It is said that when wool is mixed with a synthetic or other fiber, the elegant hand of the wool is sacrificed. However, when our sliver having had its crimps heat-set is mixed with wool, not only the unique kind hand of wool is preserved but the desirable features of the synthetic fiber is combined with the features of wool to yield an ideal blend yarn. Furthermore, when the above-mentioned sliver is mixed with rayon, the greatest drawback of which is its lack of elasticity, the resulting yarn will possess a greatly improved hand, thus widening the application of rayon to a great extent.

EXAMPLE 3 This example show the use of a polyester fiber, Toyobo ester (a eopolyester of 9085% terephthalic acid, -15% isophthalic acid, and polyethylene glycol). A top having a sliver size of g./m. was prepared by blending of a 3-denier high-shrinking fiber which has been cut to an average fiber length of 102 mm. and has a hot-Water shrinkage of 26% and 70% of a 3-denier low-shrinking fiber (hot-water shrinkage 0.12%) which has been cut to an average fiber length of 76 mm., by the conventional spinning method. The top was wound in a package of 40 cm. in diameter and cm. in length, with a net weight of 3 kg. It had a fiber density of 0.08 g./cm. After the wooden bobbin was removed, the hollow-cylindrical top, as shown in FIG. 5b, was treated with saturated steam in the same manner as Example 2, where upon very delicate and fine crimps were produced and heat-set in all the fibers forming the sliver.

The crimped slivers prepared in the above manner may be made into a yarn of the desired twist and count by the conventional spinning method, according to the end use. In this manner, products having such improved characteristics as described in Examples 1 and 2 can be manufactured.

It is also possible to manufacture a yarn by mixing the above slivers with a similar or dissimilar kind of fiber as in Example 2.

EXAMPLE 4 It is also possible to employ different kinds of thermoplastic fibers as high-shrinking fibers and low-shrinking fibers. Thus, for example, it is possible to use an acrylic fiber as the high-shrinking fiber and a difierent kind of fiber, e.g. a polypropylene fiber, as the low-shrinking fiber. This example relates to such a case.

The high-shrinking fiber of this example was a 5-denier fiber (trademark Exlan) which was prepared by hotdrawing and breaking a tow of the acrylic synthetic fiber of Example 2 with a turbostapler. This sliver has a hotwater shrinkage of 28% and an average fiber length of I02 mm. The low-shrinking fiber was a S-denier polypropylene fiber (trademark Toyobo Pylene) prepared by cutting a tow of the low-shrinking fiber to an average fiber length of 102 mm. and passing it through an intersecting gill box. This latter sliver had a hot-water shrinkage of 0.5%. 30% of the former was mixed with of the latter to prepare a top. As fully described in Examples 2 and 3, this top was so wound that the fibers are free to shrink but there is a suitable degree of interfiber restriction. When the top was held in saturated steam at 130 C. for 10 minutes, very delicate and fine crimps were produced and the crimps heat-set in all the Exlan and Pylene fibers forming a crimped bulky sliver just as described in Examples 2 and 3. The yarn spun from this sliver by the conventional spinning method had a good bulk, due to the presence of crimps in each of its com ponent fiber. Thus, the yarn not only resembled the woolen yarn, but had all the advantages of both acrylic and polypropylene fibers. These slivers may not only be mixed into a warn as described above, but may also be mixed with other fibers. In any case, a bulky wool-like yarn with improved characteristics can be manufactured.

Although in this example, the high-shrinking fiber was an acrylic fiber (trademark Exlan), any other thermoplastic synthetic fiber can be employed so long as highshrinking properties had been imparted to the same. In such cases, use may be made of the sliver obtained by hotdrawing and breaking a tow of low-shrinking fiber with a turbostapler or other similar device, or the sliver prepared by cutting a tow of high-shrinkage fiber and carding the resulting staple.

Similarly, in this example, a polypropylene fiber (trademark Toyobo Pylene) was used as the low-shrinking fiber, but other thermoplastic synthetic fibers such as nylon, polyester, etc. may also be employed with equal success. In such instances, use may be made of the sliver prepared by cutting a toW of the low-shrinking fiber and carding the resulting staple, or the sliver prepared by hot-stretching and breaking a tow of the low-shrinking fiber with a turbostapler or other similar device and, then, heattreating the same in a relaxed state.

While, in this example, the development and heatsetting of crimps Were carried out concurrently in saturated steam at 130 C. for 10 minutes, it is also possible to produce crimps by treating the sliver with hot water or steam at l30 C. and, then, heat-setting the crimps by means of saturated steam at C. or a hot air at C.

In cases where other fibers are employed in various combinations, the conditions of said heat-treatment may be selected within the range of 80 C. to 200 C., depending upon the intrinsic properties of the fibers used, the conditions under which shrinking properties had been imparted to the fibers, and other factors.

It will be apparent from the foregoing description that this invention provides a commercially valuable method for producing a bulky yarn Which is far superior to, and distinct in may aspects from the conventional bulky yarn.

What we claim is:

1. A method of producing wool-like yarn which comprises blending high shrinking thermoplastic synthetic fibers having a hot water shrinkage of 15-35% and low or non-shrinking thermoplastic synthetic fibers, the high shrinking fibers being present in an amount of 15-85% of the total fiber blend, heat-treating the blend in the form of fibrous strands selected from the group consisting of sliver, untwisted strands and rovings and having sutficient interfiber friction to enable the high shrinking fibers to crimp when heat-treated, said heat-treating step being performed prior to spinning to produce crimps therein, setting the crimps so produced, and then spinning the same into yarn.

2. A method as claimed in claim 1 in which the crimp production and its setting are effected in the same and single heat treatment.

3. A method as claimed in claim 1 in which the blended fiber to be heat treated is in the form of a sliver having a fiber density of 0.05-0.15 g./ 0111.

4. A method as claimed in claim 1 in which the blended fiber to be heat treated is in the form of a roving having a coefficient of twist of 2-15.

5. A method as claimed in claim 1 in which the thermoplastic synthetic fibers are selected from the group consisting of acrylic, polyester and polypropylene fibers.

12?. References Cited UNITED STATES PATENTS 3,081,516 3/1963 Evans 57-140 3,146,574 9/1964' Earnshaw 57140 3,302,385 2/1967 Ruddell et a1. 57-157 3,350,871 11/1967 Pierce et a1. 57-140 JOHN PETRAKES, Primary Examiner.

Claims (1)

1. A METHOD OR PRODUCING WOOL-LIKE YARN WHICH COMPRISES BLENDING A HIGH SHRINKAGE THERMOPLASTIC SYNTHETIC FIBERS HAVING A HOT WATER SHRINKAGE OF 15-35% AND LOW OR NON-SHRINKING THERMOPLASTIC SYNTHETIC FIBERS, THE HIGH SHRINKING FIBERS BEING PRESENT IN AN AMOUNT OF 15-85% OF THE TOTAL FIBER BLEND, HEAT-TREATING THE BLEND IN THE FORM OF FIBROUS STRANDS SELECTED FROM THE GROUP CONSISTING OF SLIVER, UNTWISTED STRANDS AND ROVINGS AND HAVING SUFFICIENT INTERFIBER FRICTION TO ENABLE THE HIGH SHRINKING FIBERS TO CRIMP WHEN HEAT-TREATED, SAID HEAT-TREATING STEP BEING PERFORMED PRIOR TO SPINNING TO PRODUCE CRIMPS THEREIN SETTING THE CRIMPS SO PRODUCED, AND THEN SPINNING THE SAME INTO YARN.

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