Disclosed is a fiber for artificial hairs that is given a predetermined shape, the fiber being formed from a synthetic fibroin fiber containing a modified fibroin, and the fiber expanding when placed in a wet state and contracting when dried from a wet state. Also disclosed is a method for producing a fiber for artificial hairs that is given a predetermined shape, the method including retaining a fibroin fiber containing a modified fibroin in a state conforming to a predetermined shape. A wetted fibroin fiber may also be heated while being retained in a state conforming to a predetermined shape.

An artificial hair fiber is superior in productivity and flame retardance, and is suppressed in color unevenness. An artificial hair fiber, including polyamide; and 5 to 40 parts by mass of bromine flame retardant and 0.01 to 10 parts by mass of pigment processing pigment with respect to 100 parts by mass of the polyamide; wherein the pigment processing pigment includes a colorant and a dispersant; the dispersant is contained by 20 to 80 mass % with respect to 100 mass % of total amount of the colorant and the dispersant; the dispersant includes one or more selected from the group consisting of montanoic acid metallic salt, montanoic acid wax, polyethylene wax, and fluorine wax, is provided.

A fiber for artificial hair constituted of a resin composition containing an aliphatic polyamide. A weight average molecular weight Mw of a dissolved component obtained when the fiber for artificial hair is dissolved in hexafluoroisopropanol is 46,000 or more and less than 65,000.

A fiber for artificial hair, the fiber containing 50 parts by mass or more and 95 parts by mass or less of a vinyl chloride-based resin and 5 parts by mass or more and 50 parts by mass or less of a vinyl-based copolymer resin, in which the vinyl-based copolymer resin contains 60% by mass or more and less than 70% by mass of a styrene-based monomer unit and more than 30% by mass and 40% by mass or less of an acrylonitrile-based monomer unit on the basis of the entire vinyl-based copolymer resin.

An acrylic fiber for artificial hair may include an acrylic copolymer. The acrylic fiber has a fiber cross section including 2 to 4 T-shaped protrusions that extend radially from a central portion. Each of the T-shaped protrusions has an arc-shaped upper side that bulges in a direction away from the central portion. A circumradius of the fiber cross section is 40.0 to 60.0 μm. A distance between adjacent end portions of the corresponding upper sides of the adjacent T-shaped protrusions is 3.0 to 60.0 μm. An axial width is 10.0 μm or more. Torsional rigidity of the acrylic fiber is 0.30 to 2.0 mg.Math.cm.sup.2. The acrylic fiber for artificial hair has high volume, good texture, and good twist processability, and a hair ornament may include the acrylic fiber for artificial hair.

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

One or more embodiments of the present invention relate to a core-sheath conjugate fiber for artificial hair that includes a core and a sheath. The core is composed of a polyester-based resin composition containing a polyester-based resin as a main component, and the sheath is composed of a polyamide-based resin composition containing a polyamide-based resin as a main component. The polyester-based resin composition and the polyamide-based resin composition contain a bromine-based flame retardant. In the core-sheath conjugate fiber for artificial hair, a core-to-sheath area ratio of the core to the sheath is 2:8 to 8:2. A fiber cross-section of the core-sheath conjugate fiber for artificial hair has a flat multilobed shape, and the fiber cross-section includes a hollow portion. A ratio of an area of the hollow portion to a total area of the fiber cross-section is 5% or more and 30% or less. The hollow portion has a polygonal shape. As a result, fibers for artificial hair that have a texture similar to that of human hair, high durability, favorable curl setting properties, and high flame resistance are provided.

Provided is a strand extending in the longitudinal direction, wherein the strand includes filaments of one type having a gradient-length effect through spiral rotational twists and an irregular fine texture through self-thermal shrinking. The filaments of the strand have natural coiling characteristics that are very similar to those of natural hair of black people, and these characteristics are caused by the facts that the filaments have 3-dimensional waveforms occurred due to many fine and irregular windings or projections and that the waveforms exhibit fractal structure features and a fine kinky texture.

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).

Provided is a strand extending in the longitudinal direction, wherein the strand includes filaments of one type having a gradient-length effect through spiral rotational twists and an irregular fine texture through self-thermal shrinking. The filaments of the strand have natural coiling characteristics that are very similar to those of natural hair of black people, and these characteristics are caused by the facts that the filaments have 3-dimensional waveforms occurred due to many fine and irregular windings or projections and that the waveforms exhibit fractal structure features and a fine kinky texture.