Process for the preparation of polyesters

摘要

A process for the preparation of polyesters by reacting a di-lower alkyl ester of a dicarboxylic acid consisting mainly of terephthalic acid with an alkylene glycol consisting mainly of ethylene glycol or tetramethylene glycol and thereafter polycondensing an obtained di-glycol ester of the dicarboxylic acid and/or a low molecular weight condensate thereof, in the presence of (A) a lower alkyl p-formylbenzoate in an amount of about 50 - 1000 ppm, (B) a di-lower alkyl isophthalate in an amount of about 50 - 1000 ppm and (C) p-toluic acid and/or a mono-lower alkyl terephthalate in an amount of more than about 30 ppm, wherein the total amount of the compounds (A), (B) and (C) is not more than about 2000 ppm, to thereby form polyesters which have good qualities and excellent melt-forming properties.