JPH0138885B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is a novel method for forming spun yarn knitted fabrics and non-woven fabrics that have excellent spinnability and knitting properties, unique appearance and texture, and deep color development, and are bulky and have excellent anti-pilling dimensional stability. The present invention relates to an acrylic staple fiber having crimp characteristics. Acrylic fibers are industrially produced and sold in large quantities along with other general-purpose synthetic fibers such as polyamide fibers and polyester fibers, and have better weather resistance, bulkiness, and vivid dyeing than polyamide and polyester fibers. Although it has fiber properties most similar to wool, it is said to have other drawbacks such as low heat setting properties, low dimensional stability, and low fibrillation resistance and frosting resistance. Also, acrylic fibers are said to have low pill resistance like other synthetic fibers. Furthermore, wet spinning technology is widely adopted to produce acrylic fibers, especially staple fibers for spun yarns, and the acrylic fibers obtained by wet spinning have improved mechanical strength, especially tensile strength. If you try to do so, the shrinkage rate of the fiber will increase,
High-order processing, for example, causes problems such as uneven dyeing and significant dimensional changes during dyeing, making it difficult to produce textile products with good quality and performance with good reproducibility. In addition, the acrylic fibers produced by these wet spinning methods generally have uneven surfaces rather than smooth surfaces.
The resulting fiber products are said to have poor sliminess and are coarse and hard. Furthermore, synthetic fibers generally lack anti-pilling properties, and improvements in the appearance and quality of textile products are strongly desired. In other words, a number of proposals have been made to make acrylic fibers anti-pilling. Acrylic fiber (Japanese Patent Publication No. 41-20416), an acrylonitrile copolymer having a specific copolymerization composition, is spun, stretched, dried and densified, and heat treated under limited manufacturing processes and conditions to produce monolithic fibers. Problems such as reducing only the bending strength without reducing the tensile strength, bending strength and elongation of the yarn (Japanese Patent Publication No. 55-22564), and the problem of decreased dyeability due to the acrylonitrile content contained in the copolymer. A method of preventing this and relatively reducing strength and elongation (Japanese Patent Publication No. 47131/1983) has been proposed. However, these conventional anti-pilling acrylic fibers are designed to be anti-pilling by reducing their mechanical strength, especially their hooking, knotting or bending strength; The problem is that the process does not prevent the formation of pills per se, but that the appearance and texture of textile products inevitably change over time. On the other hand, although the purpose of the invention is different from that of the present invention, Japanese Patent Application Laid-Open No. 158375/1983 discloses that the nap that appears on the surface of napped fiber products has a decrimping rate of 30% or more (before and after heating). By mixing easily decrimpable acrylic fibers with various types of fibers that do not have easy decrimpability (a value calculated from changes in the number of crimps), it is possible to form naps that are easy to raise and have long piles. is disclosed. However, the easily decrimpable acrylic fiber disclosed herein improves the appearance and texture of fibers that do not have heat decrimpability, especially napped fiber products made of animal hair such as angora, mohair, and cashmere. It is used as a blending fiber, as long as it can be mixed with the other fiber and the crimp is removed by moist heat treatment, and there is nothing to disclose about the technical effects beyond that. The present inventors have conducted extensive research on acrylic staple fibers for spinning, which retain the characteristics of acrylic fibers, especially their bulkiness, and have improved anti-pilling properties among the conventionally known acrylic fibers. This is the discovery of an invention. That is, the purpose of the present invention is not to significantly reduce the mechanical properties such as bending and knot strength of acrylic fibers to provide anti-pilling properties, but to improve the mechanical properties, bulkiness and To provide an acrylic staple fiber for spinning which has spinnability and has significantly improved anti-pilling properties, dimensional stability, surface gloss, color development and texture. Such objects of the present invention can be achieved by an acrylic staple fiber and a spun yarn obtained from the acrylic staple fiber that simultaneously satisfy requirements (a) and (b) described in the claims. The acrylic staple fiber of the present invention has a crimping characteristic that, when immersed in hot water of approximately 80°C, the crimping is not lost if the staple fiber is restrained, and the crimping property is substantially the same as that before hot water treatment. It is necessary to have the property that the crimp is retained, but the crimp is substantially lost in the unrestrained state. That is, FIGS. 1a and 1b show acrylic staple fibers of the present invention, for example, a total denier of about 1 million D and a length of about 40 mm.
The tow has been crimped and cut, leaving approximately 12 cm at both ends, and 10 to 30 cm in the center.
FIG. 2 is a side view of the crimped acrylic fiber tow observed for changes in the crimped state after being tied with count twisted yarn, immersed in warm water at 80° C. for about 10 minutes, taken out, and then the binding yarn removed. . As shown in the figure, after the acrylic staple fiber of the present invention is treated with hot water, the binding portion 2 bound by the binding thread has the following properties:
It can be seen that, although the crimp in almost its original form is retained, the crimp has virtually disappeared in the portion where the staple fibers at both ends 1 are mutually free and unconstrained. . 2, and are side photographs showing the changes in the crimp state of the acrylic staple fiber of the present invention and the conventional acrylic staple fiber before and after the hot water treatment, respectively; 1 and 2 respectively show the crimped state of conventionally known acrylic fibers before and after hot water treatment. It can be seen that the staple fiber of the present invention has been demonstrated to have crimp characteristics similar to that of FIG. The crimp characteristic of the acrylic staple fiber of the present invention is such that in textile products such as knitted fabrics made from this fiber, unconstrained fiber ends and yarns such as fuzz and loops protrude on the surface. The crimps of the strips are selectively removed by warm or hot water treatment, and the portions that are restrained to each other by the twist inside the knitted fabric and the weave structure of the knitted fabric are
It means to substantially retain its crimped form. Therefore, the acrylic staple fiber of the present invention having such crimp characteristics and the textile product obtained from the spun yarn thereof retain the bulkiness, flexibility, and texture caused by the crimp of the staple fiber. Moreover, the fluff, loops, etc. protruding from the surface have no crimp, giving it a unique texture and appearance, and meeting the requirement (b) of the present invention described below.
The synergistic effect with the drug provides anti-pilling properties. Here, the crimp characteristic of the acrylic staple fiber of the present invention can be expressed by the crimp straightening ratio defined by the following formula, and the crimp straightening ratio is at least about 75%, preferably 85%. % or more is desirable. Crimp straightening rate = crimp degree before hot water treatment - crimp degree after hot water treatment / crimp degree before hot water treatment x 100 Here, hot water treatment is a process in which the staple fiber is immersed in hot water at about 80°C for about 10 minutes. say. Moreover, the degree of crimp is a value determined by the following measuring method. (1) Attach the single threads randomly to the smooth paper with the specified amount of slack. (2) Attach the test piece to the upper and lower clips of the testing machine and cut the smooth paper near the upper clip. (3) Apply an initial load (2 mg/d) and read the length. (4) Next, apply the specified load (300mg/d),
After 30 seconds, measure the length. Degree of crimp (%) = B-A/B×100 (A: Length when initial load is applied B: Length when specified load is applied) The above degree of crimp of the acrylic staple fiber of the present invention The number of crimp is not particularly limited, and can be selected as appropriate depending on the use and purpose of the product, but the degree of crimp is 5-5.
20%, preferably 10-18%, the number of crimps is 5-
It is preferable to apply the coating at 20 peaks/inch, preferably in the range of 9 to 15 peaks/inch. In addition, the single yarn fineness of the staple fiber is 0.5 to 20 denier (d),
Preferably, a fiber length of 0.5 to 5 d and a fiber length of 32 to 128 mm are appropriately selected and used. In addition to the above requirement (a), the acrylic staple fiber of the present invention has fiber physical properties of requirement (b), that is, a tensile strength of at least 3.5 g/d, preferably 3.8.
g/d or more, knot strength of about 1.4 to 2.0 g/d, preferably 1.5 to 1.8 g/d, and boiling water shrinkage of 4% or less, preferably 3% or less. It is. That is, the tensile strength of the acrylic staple fibers of the present invention is greater, usually at least
It is important to increase the tensile strength to 3.5 g/d, preferably 3.8 g/d or more from the viewpoint of spinnability and high-order processability of the staple fiber, and being able to increase this tensile strength is more important than the conventional resistance. Eliminates the problems associated with pill-forming acrylic fibers, which have to have lower knot strength as well as tensile strength, such as lower spinnability and knitting properties, as well as lower strength (durability) of the final product. It is. In addition, an increase in the tensile strength of acrylic fibers usually results in an increase in boiling water shrinkage, resulting in a decrease in dimensional or morphological stability; for example, in cheese dyeing of spun yarns, the strong shrinkage of the spun yarns causes the inside of the cheese to deteriorate. However, the spun yarn obtained from the acrylic staple fiber of the present invention does not suffer from such problems. Furthermore, in order to impart pill resistance, which is one of the objectives of the present invention, it is only possible to achieve the above-mentioned requirement (a), the crimp property, and the specified range of knot strength at the same time. . For example, even if requirement (a) is satisfied, if the knot strength exceeds 2.0 g/d, practical anti-pilling properties will not be imparted;
If g/d is smaller than that, the spinnability of the staple fiber will be significantly reduced, making it difficult to obtain a product with stable quality and performance. Furthermore, if the boiling water shrinkage rate exceeds 4%, the shrinkage during dyeing will be large, resulting in uneven dyeing of the inner and outer layers in the case of cheese dyeing. More importantly, the knot strength increases due to shrinkage during dyeing, resulting in a problem in that the pill resistance of the resulting knitted fabric deteriorates.
Note that if the boiling water shrinkage rate is too low, the shape of the cheese after dyeing will deteriorate, so it is preferably 0.5% or more. In the acrylic staple fiber of the present invention, its cross-sectional shape is circular or semicircular, and its surface is made smoother, thereby achieving anti-pilling properties due to requirements (a) and (b) of the present invention. Advantageously, gloss, resistance to fibrillation or frosting, and sliminess can be improved. For example, FIG. 3 is a micrograph of a cross section and a side surface of an acrylic fiber obtained according to one embodiment of the present invention and a commercially available acrylic fiber, where indicates the fiber of the present invention, and indicates the commercially available acrylic fiber. As is clear from FIG. 3, the acrylic fiber of the present invention has a circular cross section and an extremely smooth surface. Next, the method for manufacturing the staple fiber of the present invention can only be obtained by specifying the manufacturing process and conditions, and cannot be obtained simply by applying known methods. A typical manufacturing method thereof will be explained below. First, as an acrylonitrile copolymer, at least 93 mol% of acrylonitrile (AN) is used.
0.1 to 0.7 mol% of a copolymerizable sulfonic acid group-containing vinyl monomer, preferably 0.25 to 0.45 mol%, and 6 mol% of other vinyl group-containing monomers.
Hereinafter, an AN copolymer copolymerized preferably in an amount in a range of 3 to 4.5 mol% is used. If the copolymerization rate of the sulfonic acid group-containing vinyl monomer exceeds 0.7 mol %, the spinnability will be significantly reduced, and the dyeing speed will also be excessive, making it easy to cause uneven dyeing. On the other hand, if the copolymerization rate is less than 0.1 mol%, the gloss and dyeability of the fiber will decrease, making it impossible to obtain the high color development characteristic of acrylic fibers. Further, when the copolymerization amount of the copolymerized component of the sulfonic acid group-containing comonomer contained in the AN-based copolymer exceeds 6 mol%, the boiling water shrinkage rate is 4% or less,
Moreover, it is difficult to manufacture the acrylic staple fiber of the present invention, which has a knot strength of 2.0 g/d or less. That is, as the copolymerization amount of the copolymerization component increases, the stretchability improves and a product with good dyeability can be obtained, but in addition to the decrease in heat setting property, the residual shrinkage rate increases and It becomes difficult to produce acrylic fibers with boiling water shrinkage. On the other hand, if the copolymerization rate becomes too low, it becomes difficult to obtain a dyed fiber product that satisfies the dyeability, especially the deep color level, and the spinnability also decreases, which is not preferable. Here, the copolymerization components include sulfonic acid group-containing vinyl monomers such as vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, P-styrene sulfonic acid and their metal salts or ammonium salts, acrylic acid, methacrylic acid, and their like. Examples include carboxyl group-containing monomers such as lower alkyl esters or salts, but preferably 0.25 to 0.45
It is preferred to copolymerize 3 to 4.5 mol % of an acrylic ester, especially methyl acrylate, with mol % of a sulfonic acid group-containing monomer, especially a metal salt of methallyl sulfonic acid. Such AN-based copolymers can be used in various solvents, such as organic solvents such as dimethyl sulfoxide (DMSO), dimethyl formamide (DMF), and dimethyl acetamide (DMAC), concentrated aqueous solutions such as zinc chloride and rhodan salt, and inorganic solvents such as nitric acid. Dissolved in a system solvent, preferably an organic solvent, with a monomer concentration of about 15-25
It is wet-spun as a stock solution for yarn protection at % by weight. As for the spinning bath, the amount of solvent should be 60-80%, preferably 65-80%.
A highly concentrated bath containing 75% of the above solvent is preferable, and by using such a highly concentrated bath, it is possible to produce acrylic fibers having a circular to oval shape and smooth fiber cross-sectional shape, which is the object of the present invention. can be manufactured advantageously. The temperature of the spinning bath is preferably in the range of about 15 to 50°C, preferably 30 to 45°C, from the viewpoint of spinnability and devitrification resistance. Next, the coagulated yarn coagulated in the spinning bath is 30%
It is stretched approximately 4 to 8 times, preferably 4.5 to 6 times, in the following DMSO aqueous solution. This stretching ratio is approximately 4
Tensile strength is at least 3.5g/d
It is difficult to obtain a high-strength fiber, and if the stretching ratio exceeds 8 times, the knot strength becomes 2.0 g/d or more, which is not preferable. The drawn yarn thus obtained is heated in warm water, e.g.
After sufficiently removing the solvent contained in the yarn in ~60°C water, the temperature is about 120~170°C, preferably 130~170°C.
It is heated at 165° C. with a relaxation of 5% or less, preferably 0 to 3.5%, and is dried and densified. This densified acrylic fiber is then processed at a temperature of about 105-135°C, preferably 115-130°C, at least 15 mg/d, preferably 35
Under a tension of mg/d, tension steaming is set so that the relaxation rate is 5% or less. When the relaxation rate exceeds 5%, the knot strength becomes too high and the pill resistance deteriorates. Thus, the tension-steam-set yarn is mechanically crimped under milder heat treatment conditions than the tension-steam-set heat treatment conditions, ie, at about 60-90°C. The mechanically crimped yarn is then set to a predetermined fiber length without being subjected to the crimping and fixing heat treatment normally applied to acrylic staple fibers. As described above, it is necessary for the acrylic fiber staple fiber of the present invention to retain the thermal history imparted in the tension steaming set, and by retaining such a thermal history, the requirements of the present invention ( This makes it possible to produce staple fibers that satisfy b). The acrylic crimped staple fiber of the present invention can be applied not only to single spun yarns but also to ordinary acrylic fibers.
It can be used for various purposes as a blended spun yarn with wool, cotton, etc. In particular, blended yarns with wool are useful for men's shirts, sweaters, women's slacks, skirts, tights, socks, athletic clothing, etc. The staple fiber of the present invention used in this case has a single yarn fineness of 1.5 to 5d and a fiber length of 51. ~128
mm, degree of crimp 8 to 15%, and number of crimp 8 to 15 threads/inch is preferred. Further, when blending wool with wool, it is preferable to blend the staple fiber of the present invention within a range of 50 to 95%. The acrylic crimped staple fiber of the present invention has many excellent features as described above, but
In particular, the textile products obtained from the spun yarn of the staple fiber alone have the following characteristics. (1) Excellent spinning performance, without problems such as single fiber breakage, shedding, yarn unevenness, and yarn breakage during the spinning process, unlike acrylic fibers that have anti-pilling properties by reducing strength or mechanical damage. has. (2) When spun yarn or knitted fabric products are subjected to dyeing or other hot water treatment, the acrylic crimped staple fibers are bundled or bundled, and the crimping occurs in the areas where the single fibers are mutually restrained. The mechanical crimp of the fiber ends, which are substantially retained and protrude freely onto the surface of the spun yarn or knitted fabric, are selectively eliminated. Therefore, the protruding ends of the uncrimped fibers have no crimp, and the fibers have a circular or oval cross section and a smooth surface, so they are difficult to entangle with each other. That is, it has anti-pilling properties. (3) Moreover, the fiber ends protruding from the surface of the spun yarn or knitted fabric product have virtually no crimps, their surface smoothness, and their circular to semi-circular cross-sectional shape, Unlike acrylic fibers, it has a unique slimy texture and luster, and especially in dyed products, it exhibits vivid and deep coloring. (4) Even if the surface of spun yarn and knitted fabric products has increased fuzz or raised naps, it has much better anti-pilling properties than conventional acrylic fibers, and since there is no crimp, it has a fur-like appearance. Indicates texture and luster. Hereinafter, the acrylic staple fiber of the present invention will be explained in more detail with reference to Examples. Example 1 A spinning stock solution was prepared by solution polymerizing 95.3 mol % of acrylonitrile, 4.3 mol % of methyl acrylate, and 0.4 mol % of sodium methallylsulfonate in dimethyl sulfoxide. The obtained stock solution had a viscosity of 200 poise/45°C and a concentration of 22.0% by weight. This stock solution was heated at 35°C using a nozzle with a hole diameter of 0.055mmφ.
After discharging into a 72% dimethyl sulfoxide aqueous solution at a controlled temperature to complete coagulation, it was placed in hot water at 98°C.
It was stretched 5.5 times. The obtained yarn was thoroughly washed with warm water, dried at 160°C (tensioned state), and subsequently subjected to tensioning treatment (straight memory fixation) at 120°C using a continuous steam treatment machine. This yarn was preheated at 75°C, mechanically crimped, and then dried with hot air at 80°C (in a free state) to obtain an acrylic fiber tow. The obtained tow has a single yarn fineness of 2.0
Denier, strength 3.95g/d, knot strength 1.65g/
d. It had physical properties of a Ken shrinkage number of 12 peaks/inch, a Ken shrinkage rate of 14%, and a boiling water shrinkage rate of 2.5%. In addition, the cross-sectional shape of the fiber has a cross-sectional circularity with a vertical/width ratio of 1.1/1.0, and is substantially circular, and the surface of the single fiber has small irregularities and is extremely smooth as shown in Figure 3. It was hot. Using this thread, as shown in Figure 1a, a sample with a total denier of 1 million D and a length of 40 cm was made, with approximately 12 cm of both ends left unrestricted and 16 cm of the central part tied together, and then placed in boiling water. After soaking for about 10 minutes, it was taken out, the binding yarn was removed, and changes in the crimp form were examined. As shown in Figure 2, the densification has disappeared at both ends in the unrestrained state, but the center part, which is restrained, retains almost the same densities as before the boiling water treatment, and the densities at both ends are straight. The conversion rate was 87%. Next, the yarn was cut into a length of 51 mm, and the obtained staple fiber was spun and spun using a conventional method to produce a spun yarn of 1/48. This staple fiber exhibited good spinnability similar to conventional acrylic fibers, with almost no free short fibers due to fly or yarn breakage during spinning. The knitted fabric obtained by knitting and dyeing this spun yarn using a conventional method was subjected to I, C, and I pilling tests (5 hours), and as a result, it showed grade 4 to 5 anti-pilling properties. Ta. In addition, the acrylic staple fibers protruding from the surface of the knitted fabric had lost their crimps, exhibited dark and deep dyeing, and had a soft and slimy texture. Comparative Example 1 93.3 mol% of acrylonitrile, 6.5 mol% of methyl acrylate, and 0.2 mol% of sodium methallylsulfonate were solution-polymerized in dimethyl sulfoxide to prepare a spinning dope having a concentration of 22.0% by weight. This stock solution was discharged into a 50% dimethyl sulfoxide coagulation bath kept at 30°C to complete coagulation, and then stretched 5.5 times in hot water at 98°C. After thoroughly washing the obtained filament with warm water,
Dry at ℃ (under tension). The yarn is preheated at 75°C, mechanically crimped, fixed with steam at 110°C, residual shrinkage is removed, and dried in a free state with hot air at 80°C to form an acrylic fiber tow. I got it. The obtained tow has a single yarn fineness of 2.0 denier and strength.
4.10g/d, knot strength 2.60g/d, Ken contraction number 12
It had the following physical properties: mounds per inch, Ken shrinkage of 15%, and boiling water shrinkage of 3.0%. The cross section of this fiber was cocoon-shaped as shown in FIG. 3, and the surface of the single fiber was rough and rough. This yarn was bundled as shown in FIG. 1a in Example 1, immersed in boiling water for 10 minutes, and then taken out. The yarn was removed and the crimp form was examined, but as shown in Figure 2, not only the portion where the yarn was wrapped and restrained, but also the free portion, the crimp remained almost unremoved. The crimp-straightening rate of the free portion was 21%. The fibers obtained above were cut to 51 mm, and the fibers were then spun and spun to produce a 1/48 spun yarn. This spun yarn was knitted in a conventional manner and dyed, and the resulting knitted fabric was subjected to an ICI pilling test (5 hours). The surface fluff of the knitted fabric easily gets tangled and pill formation is noticeable, and the pill does not fall off after pill formation.1
It was classy. In addition, the staples protruding from the surface of the knitted fabric were crimped, and the texture was rough and hard, similar to that of ordinary acrylic fiber products. Comparative Example 2 97.3 mol % of acrylonitrile, 2.0 mol % of methyl acrylate, and 0.7 mol % of sodium methallylsulfonate were solution polymerized in dimethyl sulfoxide to prepare a spinning dope having a concentration of 22.0% by weight. An acrylic fiber tow was obtained using this stock solution in the same manner as in Comparative Solution 1. The obtained tow has a single yarn fineness of 2.06 denier and strength
3.23g/d, knot strength 1.38g/d, Ken contraction number 11
It had physical properties of 13% in diameter per inch, 13% in shrinkage in boiling water, and 2.4% in boiling water. As shown in FIG. 3, the cross section of this fiber was approximately circular, but the surface of the single fiber had large irregularities and was rough. Similar to Comparative Example 1, this yarn remained uncured in boiling water, and the straightening rate of the free portion was 18%. This fiber was spun using the conventional method in the same manner as in Comparative Example 1 to produce a 1/48 spun yarn. The spinnability of this fiber was poor, and a large number of loose short fibers were generated due to fly and yarn breakage during spinning. In addition, the pill resistance of the knitted fabric obtained from this spun yarn was grade 4 in the ICI test (5 hours). Examples 3 to 5, Comparative Examples 3 to 5 The physical properties and crimp characteristics of acrylic crimped staple fibers prepared in Example 1 by changing the tension steaming treatment and mechanical crimping conditions as shown in Table 1 were Shown in Table 2.

【table】

【table】

[Table] Example 6, Comparative Examples 6 to 22 Based on the manufacturing conditions shown in Table 3 (copolymer component composition, coagulation bath conditions, primary spinning draw ratio, tension steaming treatment, heat treatment conditions after mechanical crimp) , Example 1
In the same manner as above, acrylic fiber (staple fiber) having a single yarn fineness of 2 denier was produced. After that, after spinning according to the usual method,
It was dyed and knitted cloth was made. Table 4 shows the physical properties of this acrylic fiber, the presence or absence of crimp disappearance in hot water at 80° C. without restraint, the spinnability of this fiber, and the pill resistance of the final product. As shown by these results, the fiber of Example 6, whose crimp properties and fiber physical properties were within the specified ranges of the present invention, had good spinnability and anti-pilling performance. On the other hand, the fibers of Comparative Examples 6 to 18 in which the copolymerization composition, spinning draw ratio, tension steaming treatment, and heat treatment conditions after mechanical crimping were changed have crimp characteristics and/or fiber physical properties that are defined by the present invention. Since it is outside the range, it is difficult to say that it has both the desired spinnability and excellent anti-pilling properties. In addition, as shown in Comparative Examples 19 to 22, when the knot strength of the yarn that has undergone the dry densification process is reduced by secondary drawing, not only the spinnability is markedly reduced but also the boiling water shrinkage rate is reduced. The anti-pilling properties of the final product after dyeing were poor because of the high

【table】

[Table]

【table】

[Table] Example 7, Comparative Examples 23 to 25 A spinning dope solution polymerized with the copolymerization composition ratio shown in Table 5 was spun in the same manner as in Example 1 to obtain a dry yarn with a single filament fineness of 2 denier. . This dried yarn was subjected to tension steaming treatment under the conditions shown in Table 5.
After applying crimp and heat treatment to fix crimp, it is 51mm as it is.
Cut to length, then spun and spun using conventional methods to 1/2 length.
48 spun yarns were produced. After dyeing and knitting this spun yarn, anti-pilling properties were evaluated. The results are shown in Table 6. As shown by these results, the fiber of Example 7, which has crimp characteristics and fiber physical properties within the specified range of the present invention, has good spinning rotation speed, yarn breakage, and yarn strength, which indicate spinning performance, and has good quality in the final product. Anti-pilling properties were also good.
On the other hand, the fibers of Comparative Examples 23 to 25 cannot be said to have both excellent spinnability and anti-pilling properties because the crimp properties and fiber physical properties are outside the specified range of the present invention.

[Table] Sodium lylsulfonate.

[Table] Example 8 70% of the acrylic staple obtained in Example 3 and 30% of wool were blended to obtain a 1/38 spun yarn. The spinnability was similar to that of regular acrylic and wool blends, and was good. A men's shirt (single jersey, jersey) was made using the obtained spun yarn, and its pill resistance was evaluated. The ICI pill test was grade 4-5, which was good.
In addition, a one-season wearing test was conducted, and almost no pill generation was observed, indicating that the product was more effective than conventional products.

[Brief explanation of drawings]

FIG. 1 is a plan view schematically showing changes in the crimp characteristics of the product of the present invention due to hot water treatment. Figure a shows the state in which the central part of the acrylic fiber was wrapped with a binding thread, leaving both ends of the acrylic fiber before hot water treatment. b shows the crimp form when the binding yarn is removed after hot water treatment in the state of a.
FIG. 2 is a photograph showing the change in crimp form before and after hot water treatment, and FIG. 3 is a microscopic photograph of the cross section and side surface of the present invention and various commercially available acrylic fibers.

Claims (1)

[Scope of Claims] 1. Comprised of an acrylonitrile-based copolymer containing acrylonitrile as a main component, novel crimp characteristics and fiber physical properties that satisfy the following requirements (a) and (b) are integrally combined. Acrylic staple fiber. (a) The crimps imparted to the staple fiber when immersed in hot water at approximately 80°C retain their crimps under restraint, but substantially disappear when unrestrained. to do. (b) The staple fiber has a tensile strength of at least 3.5 g/d, a knot strength of about 1.4 to 2.0 g/d, and a boiling water shrinkage of 4% or less. 2. The number of crimps of the acrylonitrile staple fiber in claim 1 is about 5 to 20.
The number of crimps per inch and the crimp degree is 5 to 20%, and by hot water treatment of requirement (a), the crimp number and crimp degree are substantially maintained under restraint, and the crimp is reduced under unrestrained conditions. An acrylic staple fiber that has novel crimp characteristics and fiber physical properties that have a crimp straightening ratio of at least about 70% using the following formula, which indicates the degree of loss. Crimp straightening rate (%) = crimp degree before hot water treatment - crimp degree after hot water treatment / crimp degree before hot water treatment × 100