| 摘要 |
PURPOSE:To easily obtain an ultrafine polyester fiber by applying an alkali-thinning stimulating agent to a split-type conjugate fiber consisting of two kinds of polyesters: a modified and an unmodified polyester and subsequently subjecting it to an alkali- thinning treatment to easily dissolve and remove the modified side not less than a specific amount under suppressing the thinning of the unmodified side. CONSTITUTION:A split-type conjugate fiber is composed of (A) a modified polyester component having a recurring unit of ethylene terephthalate containing a polyalkylene glycol and an organic sulfonic acid salt or copolymerized with adipic acid and 5-sodium sulfoisophthalate and (B) an ordinary unmodified polyester having a recurring unit of ethylene terephthalate, wherein the component B is multiply split by the component A. The split-type conjugate fiber is incorporated with an alkali-thinning stimulating agent, e.g. an adduct of a polyhydric alcohol at a ratio of >= mol. of ethylene oxide by immersing into its solution and subjected to a heat treatment at >=100 deg.C. By this treatment, an alkali-thinning rate of the component A is made >=20 times faster than that of the component B. Then, the conjugate fiber is subjected to an alkali-thinning treatment to dissolve >=80wt.% of the component A and the objective ultrafine polyester fiber consisting mainly of the unmodified polyester of the component B is easily obtained. |
