| abstract |
PURPOSE: To obtain polybutylene terephthalate excellent in heat stability, etc., by adding an alkali metal salt of hypophosphorous acid prior to the completion of the polycondensation reaction, in reacting terephthalic acid (derivative) with 1,4-butanediol. n CONSTITUTION: In producing polybutylene terephthalate from 1,4-butanediol and terephthalic acid or its derivative, e.g., dimethyl terephthalate, an alkali metal salt of hypophosphorous acid in an amount of 50W2,000ppm based on the polybutylene formed is added after the esterification or transesterification reaction and before the start of the polycondensation reaction, and the mixture is polycondensed. This can prevent discoloration of polybutylene terephthalate, improve hydrolysis resistance, heat resistance, etc., decrease the amount of tetrahydrofuran produced as a by-product, and provide good-quality polybutylene terephthalate. n COPYRIGHT: (C)1982,JPO&Japio |