Abstract: A false twist yarn includes dyeable polyolefin fibers characterized as being polymer alloy fibers each having a sea-island structure in which a polyolefin (A) is the sea component and a polyester (B) having cyclohexanedicarboxylic acid compolymerized therein is the island component, and in which the dispersion diameter of the island component in a fiber cross section is 30-1000 nm, wherein the number of the polymer alloy fibers is three or more, and the polymer alloy fibers have physical properties (1) and (2): (1) crimp recovery (CR) being 10-40%; and (2) hot-water dimensional change being 0.0-7.0%. The polyolefin false twist yarn is capable of developing vivid and profound colors even though the polyolefin fibers therein are light in weight.

Abstract: A false twist yarn includes dyeable polyolefin fibers characterized as being polymer alloy fibers each having a sea-island structure in which a polyolefin (A) is the sea component and a polyester (B) having cyclohexanedicarboxylic acid compolymerized therein is the island component, and in which the dispersion diameter of the island component in a fiber cross section is 30-1000 nm, wherein the number of the polymer alloy fibers is three or more, and the polymer alloy fibers have physical properties (1) and (2): (1) crimp recovery (CR) being 10-40%; and (2) hot-water dimensional change being 0.0-7.0%. The polyolefin false twist yarn is capable of developing vivid and profound colors even though the polyolefin fibers therein are light in weight.

Abstract: A dyeable polyolefin fiber includes a sea-island structure in which a polyolefin (A) is the sea component and a copolyester (B) obtained by copolymerizing cyclohexanedicarboxylic acid is the island component, the polyolefin fiber characterized in that the dispersion diameter of the island component in a lateral cross section of the fiber is 30 to 1000 nm. The dyeable polyolefin fiber is bright, deep coloring is imparted to the lightweight polyolefin fiber, oxidative decomposition during tumbler drying and yellowing during long-term storage are minimized, and the polyolefin fiber can be suitably used as a fibrous structure.

Abstract: A sea-islands type composite fiber includes an island component that is a polymer having moisture absorbability; a ratio (T/R) of a thickness T of an outermost layer to a diameter R of the fiber in a transverse cross section of the fiber of 0.05 to 0.25; and a moisture absorption rate difference (?MR) after a hot water treatment of 2.0 to 10.0%, wherein the thickness of an outermost layer is a difference between a radius of the fiber and a radius of a circumscribed circle formed by connecting apexes of the island components disposed in an outermost circle, and represents a thickness of a sea component in the outermost layer.

Abstract: A dyeable polyolefin fiber includes a sea-island structure in which a polyolefin (A) is the sea component and a copolyester (B) obtained by copolymerizing cyclohexanedicarboxylic acid is the island component, the polyolefin fiber characterized in that the dispersion diameter of the island component in a lateral cross section of the fiber is 30 to 1000 nm. The dyeable polyolefin fiber is bright, deep coloring is imparted to the lightweight polyolefin fiber, oxidative decomposition during tumbler drying and yellowing during long-term storage are minimized, and the polyolefin fiber can be suitably used as a fibrous structure.

Abstract: Provided are a polymethylpentene conjugate fiber, which is capable of imparting to a lightweight polymethylpentene fiber an ability to develop a vivid and deep color, and a porous polymethylpentene fiber, which has a lightweight, a high pore diameter uniformity and a high porosity retention ratio against an external force, said polymethylpentene conjugate fiber and said porous polymethylpentene fiber being appropriately usable as a fiber structure for woven knitted goods, non-woven fabrics, yarns, cotton waddings, etc. The polymethylpentene conjugate fiber is characterized by having an island-in-sea structure wherein the sea component comprises a polymethylpentene-based resin and the island component comprises a thermoplastic resin. The porous polymethylpentene fiber, which comprises a polymethylpentene-based resin, is characterized in that the coefficient of variation (CV) of pore diameter at the fiber cross section is 1-50%.

Abstract: Provided are a polymethylpentene conjugate fiber, which is capable of imparting to a lightweight polymethylpentene fiber an ability to develop a vivid and deep color, and a porous polymethylpentene fiber, which has a lightweight, a high pore diameter uniformity and a high porosity retention ratio against an external force, said polymethylpentene conjugate fiber and said porous polymethylpentene fiber being appropriately usable as a fiber structure for woven knitted goods, non-woven fabrics, yarns, cotton waddings, etc. The polymethylpentene conjugate fiber is characterized by having an island-in-sea structure wherein the sea component comprises a polymethylpentene-based resin and the island component comprises a thermoplastic resin. The porous polymethylpentene fiber, which comprises a polymethylpentene-based resin, is characterized in that the coefficient of variation (CV) of pore diameter at the fiber cross section is 1-50%.