Patent ID: 6528579
Filing Date: 2003-03-04
Classification: C08G

Abstract:
A process for the preparation of polyesters of a glycol and a dicarboxylic acid which comprises the following steps:a) introducing feedstock comprising one or more glycols and one or more dicarboxylic acids or monoalcohol esters thereof into a reactor vessel, b) heating the feedstock to an elevated temperature to cause the glycols and the acids or monoalcohol esters thereof to polycondense into a polyester, c) removing all of the polyester from the reactor vessel; wherein step b) is carried out in the absence of a preformed polyester (â€œzero heelâ€  process); and wherein one or more additives are added to the reaction vessel in step a), wherein the additives are selected from the group consisting of Group I metal hydroxides; and wherein at least one catalyst is added in step a) or in both step a) and b), wherein the catalyst is selected from the group consisting of compounds of antimony, iron, titanium, zirconium, zinc, cobalt, lead, manganese, and niobium.