Acrylic fiber for artificial hair, method for manufacturing said fiber, and headdress product containing said fiber

Abstract

An acrylic fiber for artificial hair includes an acrylic copolymer obtained by copolymerizing acrylonitrile, vinyl chloride and/or vinylidene chloride, and a sulfonic acid group-containing vinyl monomer; and an organic solvent that can dissolve the acrylic copolymer, where the organic solvent is present in an amount of 0.1 to 3% by mass with respect to the total mass of the acrylic fiber for artificial hair. The acrylic fiber for artificial hair has an average surface roughness of 5900 μm 2 or less in an area of 40 μm long and 80 μm wide of the side surface of the fiber.

What is claimed is: 
     
         1 . An acrylic fiber for artificial hair comprising:
 an acrylic copolymer obtained by copolymerizing acrylonitrile, vinyl chloride and/or vinylidene chloride, and a sulfonic acid group-containing vinyl monomer; and   an organic solvent that can dissolve the acrylic copolymer,   wherein the organic solvent is present in an amount of 0.1 to 3% by mass with respect to a total mass of the acrylic fiber, and   wherein the acrylic fiber has an average surface roughness of 5900 μm 2  or less in an area of 40 μm long and 80 μm wide of a side surface of the acrylic fiber.   
     
     
         2 . The acrylic fiber according to  claim 1 , wherein the organic solvent is at least one selected from the group consisting of dimethyl sulfoxide, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfone, ε-caprolactam, ethylene carbonate, and sulfolane. 
     
     
         3 . The acrylic fiber according to  claim 1 , wherein the acrylic copolymer comprises 30 to 70% by mass of the acrylonitrile, 25 to 69.5% by mass of the vinyl chloride and/or vinylidene chloride, and 0.5 to 5% by mass of the sulfonic acid group-containing vinyl monomer, with respect to a total mass of the acrylic copolymer. 
     
     
         4 . The acrylic fiber according to  claim 1 , wherein the acrylic fiber has a void fraction of 60% or less. 
     
     
         5 . The acrylic fiber according to  claim 1 , wherein the acrylic fiber has an apparent glass transition temperature of 90° C. or less,
 wherein the apparent glass transition temperature is defined as a peak temperature of dynamic viscoelasticity (tan δ) expressed by the following formula 1:
   Dynamic viscoelasticity (tan δ)=Loss modulus ( E ″)/Storage modulus ( E ′)  (1),
 
 
 wherein the loss modulus (E″) and the storage modulus (E′) are measured in accordance with JIS K 7244. 
 
     
     
         6 . A method for producing the acrylic fiber according to  claim 1 , the method comprising:
 preparing a spinning solution by dissolving an acrylic copolymer obtained by copolymerizing acrylonitrile, vinyl chloride and/or vinylidene chloride, and a sulfonic acid group-containing vinyl monomer in an organic solvent; and   wet spinning the spinning solution to form an acrylic fiber,   wherein the spinning solution comprises 8 to 16 parts by mass of water with respect to 100 parts by mass of the acrylic copolymer, and   wherein, in the wet spinning, a content of the organic solvent is adjusted to 0.1 to 3% by mass.   
     
     
         7 . The method according to  claim 6 , wherein the wet spinning comprises at least a water washing process and an oil application process,
 wherein, in the oil application process, a water-washed acrylic fiber is impregnated with an organic solvent that can dissolve the acrylic copolymer while the oil is applied to the water-washed acrylic fiber.   
     
     
         8 . The method according to  claim 6 , wherein the water washing process is performed by spraying water on the acrylic fiber and pressing the acrylic fiber sprayed with water by a nip roll. 
     
     
         9 . The method according to  claim 6 , wherein the organic solvent used in preparing the spinning solution is at least one selected from the group consisting of dimethyl sulfoxide, N,N-dimethylformamide, and dimethylacetamide. 
     
     
         10 . The method according to  claim 7 , wherein the organic solvent used in preparing the spinning solution is at least one selected from the group consisting of dimethyl sulfoxide, N,N-dimethylformamide, and dimethylacetamide. 
     
     
         11 . The method according to  claim 7 , wherein the organic solvent is impregnated into the acrylic fiber in the oil application process is at least one selected from the group consisting of dimethyl sulfone, ε-caprolactam, ethylene carbonate, and sulfolane. 
     
     
         12 . The method according to  claim 6 , the method further comprising preparing the acrylic copolymer by an emulsion polymerization method, wherein
 the acrylonitrile, the vinyl chloride and/or vinylidene chloride, and the sulfonic acid group-containing vinyl monomer are continuously polymerized in a single reaction vessel,   the sulfonic acid group-containing vinyl monomer is not introduced into the reaction vessel at the beginning of a polymerization reaction, and   the sulfonic acid group-containing vinyl monomer is continuously introduced into the single reaction vessel at a constant rate during a period from when a yield of the acrylic copolymer reaches 8 to 21% by mass of an intended amount of the acrylic copolymer until when the polymerization reaction ends.   
     
     
         13 . The method according to  claim 6 , wherein preparing the spinning solution comprises:
 forming a slurry of the acrylic copolymer comprising the acrylic copolymer, water, and the organic solvent; and   evaporating the water in the slurry after supplying the slurry to a thin film evaporator.   
     
     
         14 . The method according to  claim 6 , wherein the spinning solution further comprises a polyphosphate. 
     
     
         15 . A hair ornament product comprising an acrylic fiber for artificial hair, wherein the acrylic fiber comprises:
 an acrylic copolymer obtained by copolymerizing acrylonitrile, vinyl chloride and/or vinylidene chloride, and a sulfonic acid group-containing vinyl monomer; and   an organic solvent that can dissolve the acrylic copolymer, wherein the organic solvent is present in an amount of 0.1 to 3% by mass with respect to a total mass of the acrylic fiber for artificial hair,   wherein the acrylic fiber has an average surface roughness of 5900 μm 2  or less in an area of 40 μm long and 80 μm wide of a side surface of the fiber.   
     
     
         16 . The hair ornament product according to  claim 15 , wherein the organic solvent is at least one selected from the group consisting of dimethyl sulfoxide, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfone, ε-caprolactam, ethylene carbonate, and sulfolane. 
     
     
         17 . The hair ornament product according to  claim 15 , wherein the acrylic copolymer comprises 30 to 70% by mass of the acrylonitrile, 25 to 69.5% by mass of the vinyl chloride and/or vinylidene chloride, and 0.5 to 5% by mass of the sulfonic acid group-containing vinyl monomer, with respect to a total mass of the acrylic copolymer. 
     
     
         18 . The hair ornament product according to  claim 15 , wherein the acrylic fiber for artificial hair has a void fraction of 60% or less. 
     
     
         19 . The hair ornament product according to  claim 15 , wherein the acrylic fiber has an apparent glass transition temperature of 90° C. or less,
 wherein the glass transition temperature is defined as a peak temperature of dynamic viscoelasticity (tan δ) expressed by the following formula 1:
   Dynamic viscoelasticity (tan δ)=Loss modulus ( E ″)/Storage modulus ( E ′)  (1),
 
 
 wherein the loss modulus (E″) and the storage modulus (E′) are measured in accordance with JIS K 7244. 
 
     
     
         20 . The hair ornament product according to  claim 15 , wherein the hair ornament product is at least one selected from the group consisting of a fiber bundle for hair, a hair weave, a wig, a braid, toupee, a hair extension, and a hair accessory.