Patent ID: 6559271
Filing Date: 2003-05-06
Classification: B29C,B29K,C08G,Y10T

Abstract:
Method for producing polyesters with a reduced content of free acetaldehyde from terephthalic acid and ethylene glycol via a catalysed polycondensation in the melt in whicha) the catalyst is added before the polycondensation, b) after reaching an intrinsic viscosity (IV) of the melt between 0.63 and 1.00, which is achieved without solid-state postcondensation, an inhibitor is added for deactivation of the catalyst and c) next an excess of a substance which bonds the free acetaldehyde is added so that even subsequently released acetaldehyde is bonded, a temperature beneath 280Â° C. being maintained during the entire course of the polycondensation.