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 and an organic solvent that can dissolve the acrylic polymer, wherein the acrylic polymer includes 29.5 to 79.5% by weight of acrylonitrile, 20 to 70% by weight of vinyl chloride and/or vinylidene chloride, and 0.5 to 5% by weight of a sulfonic acid-containing vinyl monomer with respect to a total weight of the acrylic polymer, and wherein a content of the organic solvent in the acrylic fiber is 0.1 to 3% by weight.

The present invention is to provide a fiber for artificial hair which can freely change the hairstyle at home while maintaining the wave shape of the fiber.

A fiber for artificial hair having a bending rigidity maintaining ratio defined by formula (1) is 40 to 80% and a heat shrinkage ratio defined by formula (2) is 0.0 to 5.0% is provided.

bending rigidity maintaining ratio (%)=100{(bending rigidity in a state after conditioning for 24 hours at 30 C.90% RH)/(bending rigidity in a state after conditioning for 24 hours at 23 C.50% RH)}(1)

heat shrinkage ratio (%)=100{(length before heat treatment)(length after heat treatment for 5 min at 155 C.)}/(length before heat treatment)(2).

Described are antibacterial acrylic artificial hair fibers containing chitosan and a nonionic surfactant. The amount of chitosan extracted with diluted acetic acid is 0.005% by weight to 0.4% by weight. The amount of chitosan extracted with concentrated hydrochloric acid is 0.013% by weight to 1.3% by weight. The nonionic surfactant contains a sorbitan fatty acid ester and a polyoxyethylene triglyceride. The amount of the nonionic surfactant is 0.1% by weight to 0.9% by weight, and the percentage of the sorbitan fatty acid ester in the nonionic surfactant is 20% by weight to 90% by weight.

The present disclosure relates to a core-sheath conjugate fiber for artificial hair including a core part and a sheath part, wherein the core-sheath conjugate fiber for artificial hair is a colored fiber, a color difference between the core-sheath conjugate fiber for artificial hair and the core part is 3.0 or more, and a color difference between the core-sheath conjugate fiber for artificial hair and the sheath part is also 3.0 or more. Provided are a core-sheath conjugate fiber for artificial hair capable of realizing deep colors and having a good appearance close to that of human hair, a hair ornament product including the core-sheath conjugate fiber, and a production method.

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 ?m.sup.2 or less in an area of 40 ?m long and 80 ?m wide of the side surface of the fiber.

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.

Modacrylic fibers for artificial hair include a modacrylic polymer; and a condensed phosphate. The modacrylic 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 sulfonic acid group containing vinyl monomer, with respect to a total mass of the modacrylic polymer. A content of the condensed phosphate in the modacrylic fibers is 0.05 to 0.57% by mass.

A fiber bundle for artificial hair contains two or more types of core-sheath conjugate fibers having different core-to-sheath area ratios. Each of the core-sheath conjugate fibers includes a core and a sheath, and the core-to-sheath area ratio is represented by the area ratio between the core and the sheath. In each of the core-sheath conjugate fibers, the core includes a polyester resin composition containing a polyester resin, and the sheath includes a polyamide resin composition containing a polyamide resin. The standard deviation of the ratios of the core cross-sectional area to the fiber cross-sectional area of the core-sheath conjugate fibers contained in the fiber bundle for artificial hair is 0.15 or more. The fiber bundle for artificial hair has touch and appearance similar to those of human hair, and have favorable curl setting properties and usage durability, and a hair ornament product including the same are provided.

To provide a reversibly thermochromic composite fiber having a reversible color change due to a temperature change, having such excellent flame retardancy that flame is hard to spread even if ignition occurs once, and having high safety. [Solution] Disclosed is a sheath-core type reversibly thermochromic composite fiber including a core comprising a resin, a reversibly thermochromic pigment, and a flame retardant, and a sheath comprising a resin and a flame retardant.