Ultra-fine fibers of a thermoplastic polyester elastomer, fiber entangled body of the ultra-fine fibers, artificial leather, and a manufacturing method of the ultra-fine fibers

摘要

PROBLEM TO BE SOLVED: To provide an entangled fiber web comprising an ultra fine fiber of a polyester elastomer, the fibers tending not to stick together in bundles and, even when they are stuck to form bundles, the bundles can be easily opened; especially an ultra fine fiber of a polyester elastomer which is favorably used as a base material of artificial leather.SOLUTION: Provided is an ultra fine fiber produced by hot water extraction of a water-soluble thermoplastic resin from a sea-island type fiber containing a water-soluble thermoplastic resin as a sea component and a thermoplastic polyester elastomer as an island component, where average fineness is 0.001 to 0.5 decitex and a deflection temperature under load of the thermoplastic polyester elastomer is 100°C or higher.