ACRYLIC FIBERS, METHOD FOR MANUFACTURING SAME, AND SPUN YARN AND KNITTED FABRIC USING SAID FIBERS

Abstract

Provided are: acrylic fibers having 2-7% boiling water shrinkage and formed by the side-by-side conjugation of a copolymer A, which contains 5-10 mass % of an unsaturated monomer that can form a copolymer with acrylonitrile units, and a copolymer B, which contains 2-5 mass % of unsaturated monomer units that can form a copolymer with acrylonitrile units and 0.2-1.5 mass % of sulfonic acid group-containing monomer units; a method for manufacturing said fibers; a spun yarn containing said fibers; and a knitted fabric obtained from said spun yarn. The single fiber fineness of the heat-treated acrylic fibers is 1.7-6.6 dtex, the bulkiness is at least 380 cm3/g, the percentage of crimp is at least 15%, and the product (DKSDKE) of the knot strength (cN/dtex) and the knot elongation (%) is 10-25. The acrylic fibers have excellent crimp characteristics and anti-pilling properties.

Claims

1. An acrylic fiber, which has a crimp rate measured in accordance with JIS L1015 (2010) of 15% or higher; and a bulkiness of 380 cm.sup.3/g or greater, wherein the bulkiness is an average value of bulkiness of three samples and each bulkiness of each sample is measured by collecting approximately 10 grams of the acrylic fiber cut into 51 mm-long pieces, and opening the fiber until almost no fiber adhesion is observed; collecting 1.5 grams of the opened acrylic fiber; dividing the collected fiber into batches of approximately 0.15 grams each, and softly dropping each batch into a 1000 mL graduated cylinder with a bottom area of 33.17 cm.sup.2 to fill the cylinder homogenously without creating any gap; lowering a 6-gram load disc into the cylinder, and measuring volume v, which is a volume in a unit of cm.sup.3, occupied by the acrylic fiber two minutes later; and calculating a degree of bulkiness by the following formula:
degree of bulkiness(cm.sup.3/g)=v1.5

2. The acrylic fiber according to claim 1, wherein a single fiber fineness is 1.7 to 6.6 dtex, and a value obtained by multiplying knot strength in a unit of cN/dtex and knot elongation by % is 10 to 25.

3. The acrylic fiber according to claim 1, wherein a number of crimps is 20 to 50 per 2.54 cm.

4. The acrylic fiber according to claim 1, wherein an acrylonitrile copolymer (A) with an acrylonitrile unit content of 90-95 mass % and an acrylonitrile copolymer (B) with an acrylonitrile unit content of 93.5-97.8 mass % are arranged to form a side-by-side bicomponent structure with an area ratio of 1:3 to 3:1 at a fiber cross-section perpendicular to a fiber axis direction.

5. The acrylic fiber according to claim 4, wherein a difference between the acrylonitrile unit content in the copolymer (A) and the acrylonitrile unit content in the copolymer (B) is 2 mass % or greater.

6. The acrylic fiber according to claim 4, wherein the copolymer (A) is formed by copolymerizing 90-95 mass % of an acrylonitrile unit and 5-10 mass % of an unsaturated monomer copolymerizable with the acrylonitrile unit, and the copolymer (B) is formed by copolymerizing 93.5-97.8 mass % of an acrylonitrile unit, 2-5 mass % of an unsaturated monomer unit copolymerizable with the acrylonitrile unit, and 0.2-1.5 mass % of a sulfonic acid group-containing monomer unit.

7. The acrylic fiber according to claim 6, wherein an unsaturated monomer unit in the unsaturated monomer copolymerizable with the acrylonitrile in the copolymers (A) and (B) is a vinyl acetate unit, and the sulfonic acid group-containing monomer unit is a sodium methallyl sulfonate unit.

8. The acrylic fiber according to claim 1, wherein a shrinkage rate is 2-7%.

9. A method for manufacturing an acrylic fiber, the method comprising: preparing a spinning dope (A) by dissolving a copolymer (A) with an acrylonitrile unit content of 90-95 mass % in a solvent; preparing a spinning dope (B) by dissolving a copolymer (B) with an acrylonitrile unit content of 93.5-97.8 mass % in a solvent; and forming a side-by-side bicomponent fiber by discharging spinning dopes (A) and (B) from a nozzle into a coagulation bath with a solvent concentration of 35-60%, wherein a difference between the acrylonitrile unit content in the copolymer (A) and the acrylonitrile unit content in the copolymer (B) is 2 mass % or greater.

10. The method according to claim 9, wherein the copolymer (A) comprises 90-95 mass % of an acrylonitrile unit and 5-10 mass % of an unsaturated monomer copolymerizable with the acrylonitrile unit, and the copolymer (B) comprises 93.5-97.8 mass % of an acrylonitrile unit, 2-5 mass % of an unsaturated monomer unit copolymerizable with the acrylonitrile unit, and 0.2-1.5 mass % of a sulfonic acid group-containing monomer unit.

11. The method according to claim 9, wherein the unsaturated monomer copolymerizable with the acrylonitrile unit in the copolymers (A) and (B) is a vinyl acetate, and the sulfonic acid group-containing monomer is a sodium methallyl sulfonate.

12. The method according to claim 9, further comprising: forming a side-by-side bicomponent fiber by discharging the spinning dope (A) and the spinning dope (B) from a nozzle into a spinning bath; conducting a primary drawing at a draw ratio of 3.0-5.0 times; conducting a relaxation heat treatment under saturated steam of 90-230 kPa; and conducting a secondary drawing at a draw ratio of 1.05-1.20 times.

13. A spun yarn, comprising: the acrylic fiber according to claim 1 at 30 mass % or greater.

14. The spun yarn according to claim 13, further comprising a conductive acrylic fiber in a range of 3-15 mass %.

15. A knitted fabric, comprising: the spun yarn according to claim 13 at 50 mass % or greater, wherein an anti-pill grade is four or higher.

16. The knitted fabric according to claim 15, wherein a dimensional change of the knitted fabric after washing 10 times is 3% or lower in both vertical and horizontal directions.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] Acrylic fibers of the present invention have a crimp rate of 15% or higher and bulkiness of 380 cm.sup.3/g or greater.

[0036] A crimp rate of 15% or higher provides fiber products with excellent bulkiness and resilience. From such viewpoints, a crimp rate is preferred to be at least 17%, more preferably at least 20%, and its upper limit is preferred to be no greater than 30% because such a rate can prevent the texture of the fiber products from hardening.

[0037] A degree of bulkiness of 380 cm.sup.3/g or greater provides fiber products with excellent bulkiness and resilience. From such viewpoints, the degree of bulkiness is more preferred to be at least 440 cm.sup.3/g, and its upper limit is preferred to be no greater than 600 cm.sup.3/g, because such a degree of bulkiness prevents the texture of the fiber products from hardening.

[0038] Acrylic fibers related to the present invention are preferred to have a single fiber fineness of 1.7 dtex6.6 dtex, and the value obtained by multiplying knot strength (cN/dtex) and knot elongation (%) is preferred to be 1025.

[0039] A single fiber fineness of at least 1.7 dtex provides fiber products with excellent bulkiness and resilience similar to those of wool. A single fiber fineness of no greater than 6.6 dtex prevents fiber products from developing a hardened rough texture. From such viewpoints, the single fiber fineness is more preferred to be 2.2 dtex5.6 dtex.

[0040] The value obtained by multiplying knot strength (cN/dtex) and knot elongation (%) is preferred to be 1025, more preferably 1525 in the acrylic fibers related to the present invention. In the present application, knot strength (cN/dtex) may be referred to as DKS, and knot elongation (%) as DKE.

[0041] If the value of DKSDKE is 10 or greater, problems such as formation of fly waste in post-processing steps (for example spinning), and decrease in yarn strength are unlikely to happen. Moreover, if the value of DKSDKE is no greater than 25, an excellent anti-pill property is maintained.

[0042] The value of DKSDKE is used as an index of anti-pill property by those skilled in the art.

[0043] In the acrylic fibers related to the present invention, the number of crimps is preferred to be 2050 per 2.54 cm, more preferably 2545 per 2.54 cm.

[0044] It is preferred for acrylic fibers to have at least 20 crimps per 2.54 cm so that fiber products can achieve a texture of elasticity, compression resistance and bulkiness, whereas a number of crimps no greater than 50 per 2.54 cm can prevent the fiber products from hardening.

[0045] Acrylic fibers related to the present invention are preferred to have a side-by-side bicomponent structure of acrylonitrile copolymer (A) with an acrylonitrile unit content of 90 mass %95 mass % and acrylonitrile copolymer (B) with an acrylonitrile unit content of 93.5 mass %97.8 mass %, which are laid in an area ratio of 1:33:1 at a fiber cross-section perpendicular to the fiber axis.

[0046] When the copolymers (A) and (B) are arranged to have a side-by-side bicomponent structure, fine crimps are formed. Elasticity, rate of crimps and degree of bulkiness tend to be higher.

[0047] If the area ratio is in a range of 1:33:1, fiber products exhibit excellent bulkiness and resilience without decreasing spinning stability. From these viewpoints, the area ratio is more preferred to be 2:33:2.

[0048] When an acrylic fiber related to the present invention is spun, the side-by-side bicomponent fiber formed with copolymers (A) and (B), which are arranged in an area ratio of 1:33:1 at a fiber cross-section perpendicular to the fiber axis direction, is preferred to be contained at 80 mass % or greater in a fiber bundle discharged from one nozzle.

[0049] When a side-by-side bicomponent fiber is contained at 80 mass % or greater, fiber products have excellent bulkiness and resilience. From such viewpoints, the content of a side-by-side bicomponent fiber is more preferred to be 90 mass % or greater.

[0050] The copolymer (A) is preferred to have an acrylonitrile unit content of 90 mass %95 mass % to maintain physical properties, especially dimensional stability necessary for apparel fibers, and sufficient shrinkage.

[0051] The copolymer (B) is preferred to have an acrylonitrile unit content of 93.5 mass %97.8 mass % so that the shrinkage difference with copolymer (A) is easier to be present to provide bulkiness and resilience.

[0052] Acrylic fibers related to the present invention are preferred to have a difference of 2 or greater between the value of acrylonitrile unit content (mass %) in the copolymer (A) and the value of acrylonitrile unit content (mass %) in the copolymer (B).

[0053] If the content difference is 2 or greater, fine crimp is likely to be formed, resulting in a higher crimp rate and improved bulkiness.

[0054] Considering the above, the content difference is more preferred to be 3 or greater.

[0055] In the acrylic fibers related to the present invention, the copolymer (A) is preferred to be formed by copolymerizing 90 mass %95 mass % of an acrylonitrile unit and 5 mass %10 mass % of an unsaturated monomer unit copolymerizable with the acrylonitrile unit. The copolymer (B) is preferred to be formed by copolymerizing 93.5 mass %97.8 mass % of an acrylonitrile unit, 2 mass %5 mass % of an unsaturated monomer unit copolymerizable with the acrylonitrile unit, and 0.2 mass %1.5 mass % of a sulfonic acid group-containing monomer unit.

[0056] It is preferred to copolymerize 0.2 mass %1.5 mass % of a sulfonic acid group-containing monomer unit in copolymer (B). Dyeability differences between copolymers (A) and (B) will not be too great, and color shades variations are prevented.

[0057] Examples of an unsaturated monomer unit copolymerizable with the acrylonitrile unit are acrylic acid, methacrylic acid and their derivatives, vinyl acetate, acrylamide, methacrylamide, vinyl chloride, vinylidene chloride and the like. Among them, vinyl acetate is preferred due to its availability and cost.

[0058] Examples of a sulfonic acid group-containing monomer unit are sodium vinylbenzenesulfonate, sodium methallylsulfonate, sodium acrylamide methyl sulfonate, sodium p-sulfophenyl methallyl ether and the like. Among them, sodium methallylsulfonate is preferred due to its availability and cost.

[0059] The content of an unsaturated monomer copolymerizable with the acrylonitrile unit in the copolymer (A) is sufficient if it is 5 mass %10 mass %. When the content is 5 mass % or greater, sufficient shrinkage is maintained, and when the content is 10 mass % or less, physical properties, especially dimensional stability necessary for apparel fibers, are maintained.

[0060] Regarding an unsaturated monomer copolymerizable with the acrylonitrile unit in the copolymer (B), a content of 2 mass %5 mass % is sufficient. Such a range of content causes a difference in shrinkage between copolymers (A) and (B), and thus provides fibers with excellent bulkiness and resilience. Also, as for a sulfonic acid group-containing monomer unit, a content of 0.2 mass %1.5 mass % is sufficient. Such a range of content prevents an overly large difference in dyeability between copolymers (A) and (B), and color shades variations are prevented.

[0061] The shrinkage rate of acrylic fibers related to the present invention is preferred to be 2%7%. A shrinkage rate of 2% or higher makes latent fine crimps to provide bulky texture, whereas a shrinkage rate of 8% or less prevents hardened texture after shrinkage. Considering these features, a shrinkage rate of 4%7% is more preferred.

[0062] Also, due to a relatively low shrinkage rate, it is easier to dye the fiber without experiencing much trouble. It is also easier to conduct piece fabric dyeing in addition to commonly used yarn dyeing processes such as cheese dyeing and hank dyeing.

[0063] To determine polymerization degrees of copolymers (A) and (B), each of their specific viscosities is preferred to be 0.120.21 (when measured at 30 C. by dissolving 0.5 grams of a polymer in 100 mL of dimethylformamide). In addition, each of their molecular weights is not limited specifically as long as the value is within a normal range for manufacturing acrylic fibers. It is usually preferred to be 10,0001,000,000.

[0064] Acrylic fibers related to the present invention are manufactured by the following method, for example.

[0065] Copolymers (A) and (B) are each dissolved in a solvent normally used for spinning acrylic fibers, for example, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, and the like, and are each made into a spinning dope with a solid content of 20 mass %28 mass %. The viscosity of the spinning dope is preferred to be 50500 poise (measured at 50 C. in accordance with JIS Z8803, using a falling ball viscometer.) A solid content of 20 mass % or greater prevents a decrease in quality of the spinning dope when it is spun out, and a solid content of 28 mass % or less prevents lowered spinnability, caused by insufficient chronological stability.

[0066] Bicomponent fibers related to the present invention are manufactured when two types of spinning dope prepared as above are discharged simultaneously from a spinning nozzle. The spinning method may be selected appropriately from among known methods, but it is preferred to select a method for forming side-by-side bicomponent fibers.

[0067] Acrylic fibers related to the present invention are formed by discharging two types of spinning dope from a side-by-side bicomponent spinning nozzle into a wet-spinning coagulation bath containing a solvent. The solvent concentration in the spinning bath is preferred to be 35 mass %60 mass %, more preferably 40 mass %55 mass %. When the solvent concentration of the spinning bath is 35 mass %60 mass %, the value of DKSDKE will be in a desired range, and an excellent anti-pill property is achieved. in addition, the temperature of the spinning bath is preferred to be 20 C.45 C. if the temperature of the spinning bath is 20 C. or higher, it is relatively easy to control the temperature, and if the temperature is 50 C. or lower, an efficient spinning process is maintained. Also, when the temperature of the spinning bath is in such a range, the value of DKSDKE will be within a desired range, and an excellent anti-pill property is thereby achieved.

[0068] Next, primary drawing is conducted in hot water to have a draw ratio of 35 times. When the ratio of primary drawing is 3 times or higher, strength and elongation necessary for apparel fibers are maintained. When the draw ratio is 5 times or lower, the value of DKSDKE will be within a desired range, and an excellent anti-pill property is thereby achieved.

[0069] The draw ratio is more preferred to be 45 times.

[0070] To obtain acrylic fibers with excellent crimp and anti-pill properties as targeted in the present invention, it is necessary to conduct relaxation heat treatment in saturated steam pressure at 90 kPa230 kPa, preferably 95 kPa170 kPa. By setting the steam pressure at 95 kPa or higher, excellent crimps are obtained, and dyeability is stabilized. By setting the steam pressure at 230 kPa or lower, the value of DKSDKE will be within a desired range, and an excellent anti-pill property is thereby achieved.

[0071] When fine crimps are apparent in fibers, such fibers are difficult to open due to intense crimps, likely causing trouble during the spinning process. Therefore, it is necessary to conduct secondary drawing so as to set the fine crimps to be temporarily latent. In the present invention, it is sufficient if the draw ratio of secondary drawing is 1.051.20 times, preferably 1.051.10 times. When a draw ratio of secondary drawing is 1.05 times or higher, the fine crimps are set to be latent. A draw ratio of 1.20 times or lower does not cause excessive shrinkage, and a decrease in dimensional stability and hardened texture after shrinkage are prevented.

<Spun Yarn>

[0072] When a spun yarn is formed to contain the acrylic fiber manufactured as above at 30 mass % or greater, the latent crimps are made apparent by the heat treatment during the dyeing process or the like, and the texture tends to be similar to that of wool. By containing 30 mass % or greater of an acrylic fiber related to the present invention, an excellent anti-pill property is achieved.

[0073] When the spun yarn contains the acrylic fiber at 100 mass %, the obtained knitted fabric exhibits excellent bulkiness and resilience along with excellent anti-pill property.

[0074] Fibers to be blended with the acrylic fiber in spun yarn are not limited specifically. Both synthetic fibers and natural fibers may be used. To enhance the anti-pill property, it is preferred to blend with anti-pill synthetic fibers.

[0075] When natural fibers are blended in spun yarn, the rate of blending natural fibers is preferred to be 70 mass % or less, more preferably 30 mass % or less to prevent a decrease in the anti-pill property.

[0076] The yarn count of the spun yarn related to the present invention is preferred to be 60 or lower in metric count because bulkiness is easier to obtain if the yarn is not too thin.

[0077] The twist coefficient is preferred to be 70120. A twist coefficient of 70 or higher makes it strong enough to not cause trouble during spinning. A twist coefficient of 120 or lower makes it easier to obtain bulkiness and prevents hardened texture in knitted fabrics.

[0078] A twist coefficient satisfies the relationship in the formula below to determine the number of twists from the yarn count.

number of twists(times/meter)=twist coefficient(yarn count)

[0079] The spun yarn related to the present invention is preferred to contain a conductive acrylic fiber at 3 mass %15 mass %. Including a conductive acrylic fiber in such a range suppresses unpleasant sensations caused by static electricity when the fiber product is put on or taken off. The content of conductive acrylic fiber is more preferred to be 5 mass %12 mass % from the viewpoints of antistatic performance and cost effectiveness.

<Knitted Fabric>

[0080] Knitted fabrics related to the present invention contain the above spun yarn at 50 mass % or greater. To maintain an excellent anti-pill property and easy-care features, using the spun yarn of the present invention at 100% is preferable. However, it is also an option to interknit other spun yarn within a range that does not spoil the knitted texture, anti-pill property and easy-care features. A spun yarn that may be interknitted with the spun yarn of the present invention is not limited specifically; for example, it may be made of 100% natural fiber, 100% synthetic fiber, blended yarn of natural and synthetic fibers or the like. To obtain wool-like texture having an excellent anti-pill property of grade 4 or higher and easy-care features, it is preferred to contain an acrylic fiber related to the present invention at 30 mass % or greater of the entire knitted fabric.

[0081] Furthermore, after being washed 10 times, the dimensional change of the knitted fabric related to the present invention is preferred to be 3% or lower in both vertical and horizontal directions.

[0082] The present invention is described in details in the following examples.

EXAMPLES

[0083] Physical properties of acrylic fibers are measured by the following methods.

[0084] When fine crimps are still in a latent state, they are made apparent by conducting heat relaxation as a pretreatment for 20 minutes in boiling water. Then, acrylic fibers are dried by blowing air until the moisture content is 3 mass % or less, and opened until almost no fiber adhesion is observed.

(Single Fiber Fineness)

[0085] The fineness was determined in accordance with JIS L 1015 (vibration testing method). Testing was conducted on 50 fiber strands and the average value was used.

(Boiling Water Shrinkage Rate)

[0086] The hot water shrinkage rate was determined in accordance with JIS L 1015. Shrinking treatment was conducted in boiling water.

(Bulkiness)

[0087] An acrylic fiber of 1.5 grams, opened until almost no fiber adhesion is observed and divided into batches of approximately 0.15 grams each, is softly dropped batch by batch into a 1000 mL graduated cylinder with a bottom area of 33.17 cm.sup.2 to fill the cylinder homogenously without creating any gap. Then, a 6-gram load disc is lowered into the cylinder to determine the volume, v (cm.sup.3), occupied by the acrylic fiber two minutes later. The degree of bulkiness is calculated by the following formula:

degree of bulkiness(cm.sup.3/g)=v1.5

[0088] The above procedure is conducted on 3 samples and the average value was entered as the result.

(Crimp Rate)

[0089] The crimp rate was determined in accordance with JIS L 1015 (2010).

(Number of Crimps)

[0090] The number of crimps was determined in accordance with JIS L 1015 (2010).

(Value Obtained by Multiplying Knot Strength and Knot Elongation (DKSDKE))

[0091] The knot strength was determined in accordance with JIS L 1015 (2010) (testing under normal conditions). The elongation rate at that time was determined as knot elongation, and the multiplication product was calculated.

(Anti-Pill Property)

[0092] The anti-pill property was tested in accordance with pilling test method A specified in JIS L 1076 (2012) (ICI-type tester, running time: five hours), and classified as grades 15 based on the appearance of the fabric after testing.

(Dimensional Change Rate in Knitted Fabric)

[0093] In the center of 30 cm30 cm fabric test piece with a 20 cm square marking was washed 10 times according to the method 103 (hanging method) specified in JIS L 0217. The length of each side was measured after washing, and the dimensional change rate was calculated by the following formulas.

vertical dimensional change rate=(20(lengths of two vertical sides after washing/2))/20100(%)

horizontal dimensional change rate=(20(lengths of two horizontal sides after washing/2))/20100(%)

(Texture)

[0094] Ten people were assigned to check the texture of a knitted fabric by touch, and evaluated it based on the following criteria: [0095] [++]: all 10 people evaluated the texture to be excellent, having the same level of bulkiness and resilience as that of wool; [0096] [+]: 59 people evaluated the texture to be excellent; and [0097] []: 4 or fewer people evaluated the texture to be excellent.

Example 1

[0098] Spinning dopes were prepared by respectively dissolving copolymers (A) and (B) specified in Table 1 in a dimethylacetamide (DMAc) solvent to have a solid content of 24 mass %. In a 40 C. wet-spinning bath consisting of dimethylacetamide (DMAc) and water with a solvent concentration of 55%, the spinning dopes were discharged at a ratio of 50 mass % of copolymer (A) and 50 mass % of copolymer (B) from a bicomponent spinning nozzle and coagulated to be side-by-side. Next, after primary drawing was conducted in hot water at a draw ratio of 4.5 times, an oil agent was applied, dried by using a 150 C. hot roller, and then the fiber was crimped. Then, relaxation heat treatment was conducted on the fiber bundle under saturated steam pressure of 160 kPa to make fine crimps apparent. The fine crimps were set to be temporarily latent by conducting secondary drawing at a draw ratio of 1.1 times, and crimped again for spinning. The fiber was then cut into 51 mm-long pieces. A fiber with a single fiber fineness of 2.2 dtex was obtained. The fiber was spun to have a metric count of 1/30, and the spun yarn was formed into a tubular knitted fabric using an 18G knitting machine. The knitted fabric was dyed with a cationic dye (Cathilon Blue CD-RLH, made by Hodogaya Chemical Co., Ltd.). The results are show in Table 1.

Example 2

[0099] A fiber was obtained through the same process as that employed in Example 1 except that the solvent concentration, the spinning bath temperature and the single fiber fineness were changed to those specified in Table 1. The fiber was spun, knitted and dyed in the same way as in Example 1. The results are shown in Table 1.

Example 3

[0100] A fiber was obtained through the same process as that employed in Example 1 except that the composition of copolymer (A) and single fiber fineness were changed to those specified in Table 1. The fiber was spun, knitted and dyed in the same way as in Example 1 The results are shown in Table 1

Comparative Example 1

[0101] A fiber was obtained through the same process as that employed in Example 3 except that only the copolymer (A) of Example 3 was used. The fiber was spun, knitted and dyed in the same way as in Example 1. The results are shown in Table 1.

Comparative Example 2

[0102] A fiber was obtained through the same process as that employed in Example 1 except that only the copolymer (B) of Example 1 was used and the solvent concentration was set at 30 mass %. The fiber was spun, knitted and dyed in the same way as in Example 1. The results are shown in Table 1.

Comparative Example 3

[0103] The copolymers (A) and (B) of Example 1 were made into spinning dopes respectively and homogenously mixed. The mixture was then discharged from a spinning nozzle and coagulated so as to obtain a heterogeneous polymer composite acrylic fiber. The fiber was spun, knitted and dyed in the same way as in Example 1. The results are shown in Table 1.

Comparative Example 4

[0104] A fiber was obtained through the same process as that employed in Example 1 except that the solvent concentration was changed as specified in Table 1 The fiber was spun, knitted and dyed in the same way as in Example 1. The results are shown in Table 1.

[0105] Note that conditions set in Comparative Example 4 correspond to those described in Prior Art Literature 4 (JP S59-192717A).

TABLE-US-00001 TABLE 1 Spinning bath Shrinkage conditions rate in Single Number Co- (solvent boiling fiber Side-by- of crimps Crimp Anti- polymer Copolymer concentration/ water fineness side Bulkiness (per elongation DKS pill (A) (B) temp) (%) (dtex) ratio (%) (cm.sup.3/g) 2.54 cm) rate (%) DKE grade Texture Example 1 AN: 91% AN: 95% 55%/40 C. 6.5 2.2 93.5 400 37.2 20.7 13.9 4.5 ++ AV: 9% AV: 4.5% MS: 0.5% Example 2 AN: 91% AN: 95% 40%/30 C. 5.8 5.6 92.3 485 32.5 17.5 22.5 4 ++ AV: 9% AV: 4.5% MS: 0.5% Example 3 AN: 93% AN: 95% 55%/40 C. 4.5 5.6 89.6 440 25.8 17.1 14.1 4.5 ++ AV: 7% AV: 4.5% MS: 0.5% Comp. AN: 93% 55%/40 C. 1.2 5.6 0 265 8.7 10.6 35.9 3 Example 1 AV: 7% Comp. AN: 95% 30%/40 C. 0.8 2.2 0 220 10.1 11.5 18.5 4 Example 2 AV: 4.5% MS: 0.5% Comp. AN: 91% AN: 95% 55%/40 C. 3.8 5.6 65.5 350 16.5 13.9 28.8 3.5 + Example 3 AV: 9% AV: 4.5% MS: 0.5% Comp. AN: 91% AN: 95% 30%/40 C. 12.6 2.2 90.5 305 20.4 14.8 18.7 3.5 Example 4 AV: 9% AV: 4.5% MS: 0.5% AN: acrylonitrile, AV: vinyl acetate, MS: sodium methallyl sulfonate

Example 4

[0106] A spun yarn with a metric count of 1/30 was prepared by blending 70 mass % of the acrylic fiber obtained in Example 1 and 30 mass % of wool (66's). The spun yarn underwent a boiling water treatment at 100 C.30 minutes by using a cheese dyeing machine. Then, two strands of the spun yarn were aligned and put onto a 12G flat knitting machine to form a knitted fabric.

[0107] The knitted fabric exhibited wool-like texture, showed hardly any dimensional change after washing, and had an excellent anti-pill grade of 4.0. The results are shown in Table 2.

Example 5

[0108] A spun yarn with a metric count of 1/30 was prepared by blending 40 mass % of the acrylic fiber obtained in Example 1, 30 mass % of an anti-pill acrylic fiber with a single fiber fineness of 2.2 dtex (item type: H616, made by Mitsubishi Rayon), and 30 mass % of wool (66's). After the spun yarn underwent a boiling water treatment by using a cheese dyeing machine the same as in Example 4, the spun yarn was put onto a 12G flat knitting machine to form a knitted fabric.

[0109] As shown in Table 2, the knitted fabric exhibited a wool-like texture, showed hardly any dimensional change after washing, and had an excellent anti-pill grade of 4.5. The results are shown in Table 2.

Example 6

[0110] A spun yarn with a metric count of 1/30 was prepared by blending 90 mass % of the acrylic fiber obtained in Example 1, and 10 mass % of a conductive acrylic fiber with a single fiber fineness of 3.3 dtex (item type: TB10, made by Mitsubishi Rayon). After the spun yarn underwent a boiling water treatment by using a cheese dyeing machine the same as in Example 4, the spun yarn was put onto a 12G flat knitting machine to form a knitted fabric.

[0111] As shown in Table 2, the knitted fabric exhibited wool-like texture, showed hardly any dimensional change after washing, and had an excellent anti-pill grade of 4.5. The results are shown in Table 2.

Comparative Example 5

[0112] A spun yarn with a metric count of 1/30 was prepared to have a 100% wool (66's) content. After the spun yarn underwent a boiling water treatment by using a cheese dyeing machine the same as in Example 4. Then, two strands of the spun yarn were aligned and put onto a 12G flat knitting machine to form a knitted fabric.

[0113] The knitted fabric exhibited excellent bulkiness and resilience. However, as shown in Table 2, a significant dimensional change was observed after washing, and it had low anti-pill grade of 2. The results are shown in Table 2.

TABLE-US-00002 TABLE 2 Dimensional change rate Anti-pill (vertical/ Composition of spun yarn Blending ratio grade horizontal) Texture Example 4 acrylic fiber of Example 1 70% 4 1.9%/1.2% ++ wool 30% Example 5 acrylic fiber of Example 1 40% 4.5 1.2%/0.9% ++ anti-pilling acrylic fiber 30% wool 30% Example 6 acrylic fiber of Example 1 90% 4.5 0.9%/0.5% ++ conductive acrylic fiber 10% Comp. wool 100% 2 5.2%/5.8% ++ Example 5 30 or higher 4 or higher 3 or lower * in dimensional change rate column indicates shrinkage

INDUSTRIAL APPLICABILITY

[0114] The acrylic fibers related to the present invention have excellent crimp and anti-pill properties, and are preferable for apparel such as sweaters and jackets along with handcraft yarn.