Patent ID: 7767120

Claim:
A method for producing an aliphatic polyester multifilament crimped yarn, comprising providing a crimp to drawn multifilament fiber including a biodegradable polymer containing an aliphatic polyester as a main component by using a crimp-providing apparatus that utilizes heated air at 120-170° C., to produce a multifilament crimped yarn, wherein the aliphatic polyester multifilament crimped yarn comprises a polylactic acid aliphatic polyester having a melting point equal to or higher than 130° C., said multifilament crimped yarn has a crimp elongation rate of 3-35% after being processed with boiling water, and said multifilament crimped yarn has a breaking strength of 1-5 cN/decitex; and wherein said yarn is produced by drawing a non-drawn yarn via two-step drawing processes, in which the yarn is drawn to 1.01-3 times at the first step and to 1.01-3 times at the second step, with a drawing scale of 1.02-9 times in total.