FORFARANDE FOR KONTINUERLIG FRAMSTELLNING AV EN LINJER POLYESTER

摘要

An improved process for the continuous manufacture of linear high molecular weight polyesters by direct esterification of terephthalic acid with excess glycols in a medium comprising terephthalic acid glycol esters or their oligomers, under superatmospheric pressure at temperatures above 200 DEG C, followed by polycondensation in the presence of catalysts at from 260 DEG to 290 DEG C. The improvement is that the mixture fed to the esterification contains terephthalic acid and glycols in the molar ratio of 1:1.15 to 1:1.5 and that during the esterification from 20 to 30% by weight of the excess of glycols over the molar ratio terephthalic acid: glycols = 1:1 are continuously distilled from the reaction mixture.