Method for preparing a polyester under specific esterification conditions

Abstract

A polyester including poly(ethylene 2,5-furandicarboxylate is prepared by esterification of a starting mixture including 2,5-furandicarboxylic acid and ethylene glycol to form an ester composition, and by subjecting the ester composition thus obtained to polycondensation at reduced pressure in the presence of a polycondensation catalyst to obtain a polycondensate. The mixture is reacted under conditions such that the esterification potential as defined by Esterification Potential (EsPo)=(MR−1)*P(T), where MR represents the molar ratio of ethylene glycol over 2,5-furandicarboxylic acid, MR being greater than 1; P(T) represents the pure component vapor pressure (in bar) of water at temperature T, which is the final reaction temperature in the esterification mixture before the pressure is reduced to effect the polycondensation, is less than 0.8.