Glossy pilling-resistant acrylic fiber, method for producing same, and spun yarn and knitted fabric containing said acrylic fiber

Abstract

The present invention provides: an acrylic fiber having a fineness of 0.5 to 3.5 dtex and having excellent gloss, pilling resistance, and texture; a method for producing said acrylic fiber; and a spun yarn and a knitted fabric containing said acrylic fiber. Provided is an acrylic fiber having a filament fineness of 0.5 to 3.5 dtex, wherein the product K of the value of knot strength (cN/dtex) and the value of knot elongation (%) is from 8 to 30 inclusive, and the number of recesses having a depth of 0.1 μm or greater is 10 or fewer.

1 . An acrylic fiber, configured to have a center-line mean roughness (Ra) of 3 nm to 12 nm on the surface of a single fiber, and a single fiber fineness of 0.5 dtex to 3.5 dtex. 
     
     
         2 . An acrylic fiber, configured to have a center-line mean roughness (Ra) of 3 nm to 12 nm on the surface of a single fiber, and a product (K) of 10 to 30 obtained by multiplying the value of knot strength (cN/dtex) and the value of knot elongation (%). 
     
     
         3 . The acrylic fiber according to  claim 1 , wherein the value of a product (K), obtained by multiplying the value of knot strength (cN/dtex) and the value of knot elongation (%), is set to be 10 to 30. 
     
     
         4 . The acrylic fiber according to  claim 2 , wherein a single fiber fineness is set at 0.5 dtex to 3.5 dtex. 
     
     
         5 . The acrylic fiber according to  claim 1 , wherein the surface of a single fiber is configured to have a maximum height (Ry) of the profile set at 40 nm to 150 nm, the 30-point mean roughness (Rz) at 20 nm to 80 nm and the distance (S) between peaks of convex portions at 800 nm to 1100 nm. 
     
     
         6 . The acrylic fiber according to  claim 1 , wherein the number of recesses of 0.1 μm or deeper that are present on the surface of a single fiber is no greater than 10 when observed in a cross section perpendicular to the fiber axis. 
     
     
         7 . The acrylic fiber according to  claim 1 , comprising 92 mass % to 96.8 mass % of an acrylonitrile unit, 2 mass % to 6 mass % of a vinyl monomer unit, and 0.2 mass % to 2.0 mass % of a sulfonic acid group-containing vinyl monomer unit, wherein a single fiber tensile strength is set at 1.8 cN/dtex to 3.0 cN/dtex, a single fiber knot strength is set at 1.0 cN/dtex to 1.8 cN/dtex, and a single fiber knot elongation is set at 8% to 20%. 
     
     
         8 . A method for producing an acrylic fiber, comprising:
 forming a spinning dope by dissolving in an organic solvent an acrylonitrile-based copolymer that contains 92 mass % to 96.8 mass % of an acrylonitrile unit and 0.2 mass % to 2.0 mass % of a sulfonic acid group containing-vinyl monomer unit;   forming a coagulated fiber bundle by discharging the spinning dope in a 35° C. to 50° C. coagulation bath through the discharge ports of a spinning nozzle at a jet-stretch ratio of 0.4 to 2.2;   stretching the coagulated fiber bundle in 80° C. to 98 C.° hot water at a stretch ratio of 2 to 3.8 times;   applying oil to the fiber bundle and drying the fiber bundle; and   stretching the fiber bundle by applying dry heat to have a fiber temperature of 150° C. to 170° C. at a stretch ratio of 1.2 to 3 times,   wherein the value of a product (S), obtained by multiplying the hot-water stretch ratio and the dry-heat stretch ratio, is set to be 4 to 6.   
     
     
         9 . The method for producing an acrylic fiber according to  claim 8 , wherein the acrylonitrile-based copolymer is configured to further comprise 2 mass % to 6 mass % of a vinyl monomer unit, the solvent concentration of the coagulation bath is set to be 40 mass % to 60 mass %, and a thermal relaxation process is conducted after hot-dry stretching. 
     
     
         10 . The method for producing an acrylic fiber according to  claim 8 , wherein the temperature for the thermal relaxation process is set at 120° C. to 135° C., and a fiber relaxation ratio is set at 5% to 20%. 
     
     
         11 . A spun yarn, comprising:
 an acrylic fiber according to  claim 1  at 40 mass % or greater,   wherein the cotton count is set at 40 to 70.   
     
     
         12 . The spun yarn according to  claim 11 , further comprising a cellulose-based fiber at 10 mass % to 40 mass %. 
     
     
         13 . A knitted fabric, comprising:
 a spun yarn according to  claim 11  at 40 mass % or greater,   wherein the basis weight is set at 150 g/m 2  to 230 g/m 2 , and   the pilling-resistant property is rated at 4 or higher.   
     
     
         14 . The knitted fabric according to  claim 13 , wherein a heat-retention rate is set to be 15% to 50%. 
     
     
         15 . The acrylic fiber according to  claim 2 , wherein the surface of a single fiber is configured to have a maximum height (Ry) of the profile set at 40 nm to 150 nm, the 30-point mean roughness (Rz) at 20 nm to 80 nm and the distance (S) between peaks of convex portions at 800 nm to 1100 nm. 
     
     
         16 . The acrylic fiber according to  claim 2 , wherein the number of recesses of 0.1 μm or deeper that are present on the surface of a single fiber is no greater than 10 when observed in a cross section perpendicular to the fiber axis. 
     
     
         17 . The acrylic fiber according to  claim 2 , comprising 92 mass % to 96.8 mass % of an acrylonitrile unit, 2 mass % to 6 mass % of a vinyl monomer unit, and 0.2 mass % to 2.0 mass % of a sulfonic acid group-containing vinyl monomer unit, wherein a single fiber tensile strength is set at 1.8 cN/dtex to 3.0 cN/dtex, a single fiber knot strength is set at 1.0 cN/dtex to 1.8 cN/dtex, and a single fiber knot elongation is set at 8% to 20%. 
     
     
         18 . A spun yarn, comprising:
 an acrylic fiber according to  claim 2  at 40 mass % or greater,   wherein the cotton count is set at 40 to 70.   
     
     
         19 . The spun yarn according to  claim 18 , further comprising a cellulose-based fiber at 10 mass % to 40 mass %. 
     
     
         20 . A knitted fabric, comprising:
 a spun yarn according to  claim 18  at 40 mass % or greater,   wherein the basis weight is set at 150 g/m 2  to 230 g/m 2 , and   the pilling-resistant property is rated at 4 or higher