SEA-ISLAND COMPOSITE FIBER, ULTRAFINE FIBER, AND COMPOSITE DIE

摘要

Disclosed is a sea-island composite fiber in which the island component is ultrafine fibers having a noncircular cross-section, the ultrafine fibers being uniform in the degree of non-circularity and in the diameter of the circumscribed circle. The sea-island composite fiber comprises an easily soluble polymer as the sea component and a sparingly soluble polymer as the island component, and is characterized in that the island component has a circumscribed-circle diameter in the range of 10-1,000 nm, a dispersion in circumscribed-circle diameter of 1-20%, a degree of non-circularity of 1.2-5.0, and a dispersion in the degree of non-circularity of 1-10%.