| 摘要 |
PURPOSE:To obtain a polyester excellent in spinnability and suitable for fiber by reducing the deposition of foreign matter on the surface of a spinneret, by polycondensing a reaction product between a dicarboxylic acid (derivative) and a glycol in the presence of an Sb compound by adding a specified carboxylic acid to the reaction system. CONSTITUTION:A reaction product (X) between a dicarboxylic acid (esterifiable derivative) (a) and a glycol (b) is polycondensed in the presence of 0.01-0.1mol%, based on component (a), Sb compound, such as Sb2O3, as a polymerization catalyst (Y) by application of heat and vacuum. When the degree of polycondensation of the polycondensate exceeds 3, A mol of a carboxylic acid (Z) of formula I (wherein R1 is H or a 1-4C alkyl, n is 1 or 2, R2 is COOH, R1, a hydroxyl or the like) is added in such a way that the relationship of the formula II [wherein S is the amount (mol) of component Y added] is satisfied and that the relationship of the formulae III and IV (wherein T is a temperature of the polycondensation system, C is a COOH end group concentration of the polycondensate) can be simultaneously satisfied and the polycondensation is further continued to obtain a polyester.
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