Acrylic fiber for artificial hair, method for manufacturing said fiber, and headdress product containing said fiber
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.
1. A method for producing an acrylic fiber for artificial hair, the method comprising:
preparing a spinning solution by dissolving an acrylic copolymer obtained by copolymerizing acrylonitrile, vinyl 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,
in the wet spinning, a content of the organic solvent in the acrylic fiber is adjusted to 0.1 to 3% by mass,
the wet spinning comprises at least a water washing process and an oil application process,
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, and
the organic solvent used in preparing the spinning solution comprises dimethyl sulfoxide, and the organic solvent impregnated into the acrylic fiber in the oil application process comprises at least one selected from the group consisting of dimethyl sulfone, ε-caprolactam, and sulfolane.
2. The method according to claim 1 , 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.
3. The method according to claim 1 , the method further comprising preparing the acrylic copolymer by an emulsion polymerization method, wherein
the acrylonitrile, the vinyl 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.
4. The method according to claim 1 , 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.
5. The method according to claim 1 , wherein the spinning solution further comprises a polyphosphate.
6. The method 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 0.5 to 5% by mass of the sulfonic acid group-containing vinyl monomer, with respect to a total mass of the acrylic copolymer.
7. The method according to claim 3 , wherein the acrylic copolymer comprises 30 to 70% by mass of the acrylonitrile, 25 to 69.5% by mass of the vinyl 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.
8. The method according to claim 5 , wherein the polyphosphate is an inorganic polyphosphate.