A fiber for artificial hair, the fiber comprising a synthetic resin and a microparticle, wherein a content difference |C.sub.1-C.sub.2| between a content C.sub.1 of a microparticle of smaller than 2 ?m in particle size, and a content C.sub.2 of a microparticle of 2 ?m or larger and smaller than 5 ?m in particle size is 70% by mass or less based on the total amount of the microparticle, and the content of a microparticle of 5 ?m or larger in particle size, C.sub.3, is less than 25% by mass based on the total amount of the microparticle.

A fiber for artificial hair, the fiber comprising a synthetic resin and a microparticle, wherein a content difference |C.sub.1-C.sub.2| between a content C.sub.1 of a microparticle of smaller than 2 ?m in particle size, and a content C.sub.2 of a microparticle of 2 ?m or larger and smaller than 5 ?m in particle size is 70% by mass or less based on the total amount of the microparticle, and the content of a microparticle of 5 ?m or larger in particle size, C.sub.3, is less than 25% by mass based on the total amount of the microparticle.

An acrylic fiber for artificial hair includes an acrylic polymer, wherein the acrylic polymer includes 29.5 to 79.5% by mass of acrylonitrile, 20 to 70% by mass of vinyl chloride and/or vinylidene chloride, and 0.5 to 5% by mass of a vinyl monomer comprising a sulfonic acid group. The acrylic fiber for artificial hair includes 0.3 to 2% by mass of a good solvent for the acrylic polymer and 0.1 to 5% by mass of a compound comprising an epoxy group.

An acrylic fiber for artificial hair includes an acrylic polymer, wherein the acrylic polymer includes 29.5 to 79.5% by mass of acrylonitrile, 20 to 70% by mass of vinyl chloride and/or vinylidene chloride, and 0.5 to 5% by mass of a vinyl monomer comprising a sulfonic acid group. The acrylic fiber for artificial hair includes 0.3 to 2% by mass of a good solvent for the acrylic polymer and 0.1 to 5% by mass of a compound comprising an epoxy group.

A fiber for artificial hair formed of a polyvinyl chloride-based resin composition. The fiber for artificial hair has a value X1 of a loss tangent tans at 70? C. of 0.06 or more and 0.12 or less, when dynamic viscoelasticity is measured under the following conditions, and has a peak in a temperature range of 90? C. or higher and 110? C. or lower. (Dynamic viscoelasticity measurement conditions) The measurement is performed by sandwiching a bundle of 40 fibers for artificial hair that are arranged at a heating rate of 4? C./min and a frequency of 1 Hz.

[Problem to be solved] A method for separating fibers that separates a modacrylic fiber, a polyvinyl chloride fiber and a polyester fiber and a method for producing fibers using these fibers obtained by the method for separating fibers are provided.

[Solution] A method for separating fibers contained in a fiber mixture from the fiber mixture, the method including a step of mixing the fiber mixture containing at least two selected from the group consisting of a modacrylic fiber, a polyvinyl chloride fiber and a polyester fiber, and a liquid mixture containing calcium chloride, a nonionic surfactant and water, and a method for producing a fiber, the method including a separation step of mixing a fiber mixture containing at least two selected from the group consisting of a modacrylic fiber, a polyvinyl chloride fiber and a polyester fiber, and a liquid mixture containing calcium chloride, a nonionic surfactant and water and a step of spinning a raw material containing a fiber separated in the separation step.

[Problem to be solved] A method for separating fibers that separates a modacrylic fiber, a polyvinyl chloride fiber and a polyester fiber and a method for producing fibers using these fibers obtained by the method for separating fibers are provided.

[Solution] A method for separating fibers contained in a fiber mixture from the fiber mixture, the method including a step of mixing the fiber mixture containing at least two selected from the group consisting of a modacrylic fiber, a polyvinyl chloride fiber and a polyester fiber, and a liquid mixture containing calcium chloride, a nonionic surfactant and water, and a method for producing a fiber, the method including a separation step of mixing a fiber mixture containing at least two selected from the group consisting of a modacrylic fiber, a polyvinyl chloride fiber and a polyester fiber, and a liquid mixture containing calcium chloride, a nonionic surfactant and water and a step of spinning a raw material containing a fiber separated in the separation step.

An acrylic fiber for artificial hair includes an acrylic polymer, wherein the acrylic polymer includes 29.5 to 79.5% by mass of acrylonitrile, 20 to 70% by mass of vinyl chloride and/or vinylidene chloride, and 0.5 to 5% by mass of a vinyl monomer comprising a sulfonic acid group. The acrylic fiber for artificial hair includes 0.3 to 2% by mass of a good solvent for the acrylic polymer and 0.1 to 5% by mass of a compound comprising an epoxy group.

An acrylic fiber for artificial hair includes an acrylic polymer, wherein the acrylic polymer includes 29.5 to 79.5% by mass of acrylonitrile, 20 to 70% by mass of vinyl chloride and/or vinylidene chloride, and 0.5 to 5% by mass of a vinyl monomer comprising a sulfonic acid group. The acrylic fiber for artificial hair includes 0.3 to 2% by mass of a good solvent for the acrylic polymer and 0.1 to 5% by mass of a compound comprising an epoxy group.

The method for producing wet spun fibers/a wet formed film using a double-walled pipe type micronozzle apparatus according to the present invention is a production method, wherein, in a step of extruding an internal phase comprising a fiber/film material and a good solvent for the fiber/film material in a linear form from the circular/rectangular end of the internal pipe of the apparatus into an external phase comprising a poor solvent for the fiber/film material, the external phase flowing in the external pipe of the apparatus, the ratio of the external phase flow rate to the internal phase flow rate is set to 1 or more, and further for the wet spun fibers, the external phase line speed at the orifice portion at which the internal phase and the external phase merge is set to 0.1 ms.sup.1 or more.