COMPOSITE FIBER, HOLLOW FIBER, AND PROCESS FOR PRODUCING HOLLOW FIBER USING SAID COMPOSITE FIBER

摘要

A core/sheath composite fiber comprising a sheath part (1) formed of a water-insoluble thermoplastic polymer and a core part (2) formed of a water-soluble thermoplastic polymer is provided. A hollow fiber may be produced by treating a composite fiber having an irregular sectional shape, in which the sectional shape of the core part in a direction perpendicular to the longitudinal direction has 10 or more protrusions (3), with a hydrophilic solvent to remove at least a part of the core part from the composite fiber. In this composite fiber, a construction may be adopted wherein the sectional shape of the core part in a direction perpendicular to the longitudinal direction is an irregular sectional shape having radially extended 15 to 200 tongue or leaf protrusions, and the aspect ratio in the protrusions may be long side/short side = about 1/1 to 100/1. The water-soluble thermoplastic polymer may be a water-soluble thermoplastic polyvinyl alcohol polymer. The water-insoluble thermoplastic polymer may be a polyolefin resin and/or a polyester resin having an equilibrium moisture content of not more than 2%.