| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of producing polyester of a desired degree of polymerization, even in the case of polymerization of the polyester of poor polymerization properties, for example, poly(ethylene isophthalate) without side-reaction in a relatively short time. SOLUTION: In the melt-polymerization of polyester, bis(2-hydroxyalkyl) carboxylate and/or its oligomers are subjected to the polycondensation reaction with heat into the corresponding poly(alkylene carboxylate). In this case, bis(2- hydroxyalkyl) oxalate represented by the formula (1): HO-R-O-C(O)-C(O)-O-R-OH (R represents the same carbon skeleton as the alkylene of the polymerized polyalkylene carboxylate) is used in a prescribed amount based on the dicarboxylic acid structure units that constitute the polyester.
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