PROCESS FOR THE PREPARATION OF POLYESTER

摘要

The polyester is prepared by (1) directly esterifying dicarboxylic acids containing terephthalic acid of at least 85 mol.% and glycols containing ethylene glycol of at least 85 mol.% to obtain a mixture of bis-(2-hydroxy ethyl) terephthalate and its lower polymer, (2) polycondensating the mixture under the reduced pressure at the high temperature and (3) adding 0.01-0.1 mol.% alkaline metal salt (a) of phosphorus compound of formula (I) with respect to the total component of polyester acid (wherein, M is alkaline metal atom, R1 and R2 are hydrogen or univalent organic group) and complex compound (b) obtained by reacting cobaltic compound and low alkylphosphate. The polyester has an excellent color tone and thermal stability.