| 摘要 |
PURPOSE:To obtain inexpensively an aromatic polyester of good hue and excellent heat resistance, by adding a specified amount of a lower fatty acid anhydride to the principal materials, esterifying the mixture and polycondensing the ester while distilling a lower fatty acid from the system. CONSTITUTION:A reactor fitted with a condenser is charged with equimolar amounts of an aromatic diol and an aromatic dicarboxylic and/or hydroxycarboxylic acid and 1.01-1.50 equivalent, per equivalent of the total hydroxyl groups, of a lower fatty acid anhydride, and the mixture is esterified at normal pressure and a temperature below the b.p. of the lower fatty acid anhydride, usually, 100-160 deg.C so that the whole of the lower fatty acid anhydride may be refluxed. While unreacted lower fatty acid anhydride and the lower fatty acid formed by reaction are being distilled from the system by gradually raising the temperature, an acid exchange reaction is performed at 200-260 deg.C, and the temperature is raised to about 280 deg.C. Finally, polycondensation is performed at a temperature as high as about 250-350 deg.C and a pressure as high as 1Torr. An aromatic polyester of good hue and excellent heat resistance can be obtained economically.
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