| 摘要 |
PROBLEM TO BE SOLVED: To obtain an aliphatic polyester copolymer having biodegradability and softness and further having sufficient strength, elongation and thermal stability available to a practical use because of a high molecular weight. SOLUTION: This aliphatic polyester polymer is the aliphatic copolyester obtained by performing a condensation polymerizatiorx in the presence of a catalyst comprising a germanium compound, and has (1) 30-70mol% aliphatic hydroxy carboxylic acid unit, (2) 15-35mo1% aliphatic diol unit and (3) 15-30mol% aliphatic dicarboxylic acid unit. A part of the aliphatic hydroxy carboxylic acid unit is anα-hydroxy carboxylic acid unit and the percentage of theα-hydroxy carboxylic acid is 0.1-100mol% based on the amount of the hydroxy carboxylic acid unit and <=40mol% based on the amount of the whole constituting units. The number average molecular weight of the copolyester is 1×10<4> -2×10<5> .
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