| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing an aliphatic polyester having low branching degree, high molecular weight and suppressed molecular weight lowering and discoloration in molding. SOLUTION: An aliphatic polyester is produced by using an aliphatic diol, an aliphatic dicarboxylic acid and an aliphatic hydroxycarboxylic acid as raw materials in the presence of a group 2A, 2B or 4A element compound catalyst wherein 100-75 mol% in 100 mol% of the aliphatic dicarboxylic acid is succinic acid or its derivative and the content of malic acid in the dicarboxylic acid is≤0.60 wt.%. The production process comprises a step to proceed the esterification reaction at a prescribed reaction temperature to a prescribed esterification ratio to obtain a low-molecular product having a prescribed weight-average molecular weight and a prescribed acid value and a polymerization step to perform the polycondensation at a prescribed reaction temperature. The polymerization step of a reaction liquid having a viscosity higher than a specific level is carried out by using a twin-screw continuous polymerization reactor. COPYRIGHT: (C)2007,JPO&INPIT
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