| 摘要 |
PROBLEM TO BE SOLVED: To obtain a polyester-based composite filament suitable for an alkali weight reduction without involving problems such as inferior unwinding, inferior smoothness and soiling of guides and rollers, etc., in the case of post-processing a fiber compounded with a polymer for an alkali hydrolysis. SOLUTION: This filament is a composite fiber comprising >=2 kinds of polyesters having different alkali hydrolysis rates, and attached with 0.3-1.0 wt.% oil agent based on the composite fiber, having <=15% degree of swelling expressed by the following general formula based on a fiber obtained by using a polyester fiber having the highest hydrolysis rate. Degree of swelling (SW)=[(F1-F2)/F1]×100 where, F1: A minimum stress (N/dtex) in a natural elongation zone after leaving an oil-less un-stretched yarn for 5 days. F2: A minimum stress (N/dtex) in a natural elongation zone after leaving an un- stretched yarn applied with >=20% stock solution of the oil agent for 5 days. |
