Latent elastic composite fiber, a method for producing the same, and a method for producing a fibrous structure having elasticity during elongation and contraction

摘要

The present invention relates to a polyurethane composition comprising a polyurethane as a core and a polyester as a curing agent, wherein the ratio of the polyurethane component having allophanate crosslinking to the water-soluble or water-soluble alkaline aqueous solution is from 1/1 to 90 / 1, and the polyester component is exposed on the surface of the filament on its cross section, preferably a core-sheath composite filament. Although the core component has high tensile strength and high fracture elongation, this property is controlled by the seed component. Therefore, the filament can be formed into a textile structure with good workability similar to that of ordinary synthetic fibers, and the resulting structure has improved properties as an elastic polyurethane filament when treated with water or an alkali.