| 摘要 |
PROBLEM TO BE SOLVED: To obtain an elastic fiber reduced in a decrease in elastic recovery upon repeated elongation without detriment to heat resistance and weathering resistance by combining a polyester copolymer comprising short-chain and long-chain polyester components with a polyether through an isocyanate component. SOLUTION: A block copolymer is obtained by combining 100 pts.wt. polyester copolymer (A) comprising 50-95 wt.% short-chain polyester component represented by formula I (wherein R1 is a 6-12C aromatic hydrocarbon group; and R2 is a 2-8C alkylene) and 50-5 wt.% long-chain polyester component represented by formula II (wherein R3 is a component comprising repeating units of -R6-O- and having a number-average molecular weight of 500-5,000; and R6 is R2) with 50-500 pts.wt. polyether (B) comprising repeating units represented by formula II (wherein R4 is R2) through 10-100 pts.wt. isocyanate component (C) represented by formula IV or V (wherein R5 is a 2-15C alkylene, phenylene, or a combination of phenylene with methylene or an alkylene).
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