BigPatents India

The invention relates to a polymerization catalyst for preparing polyesters. The catalyst contains aluminium hydroxide and/or aluminium acetate as a first component and at least one phosphoric or phosphonic ester as a second component. The invention also relates to a polymerization process for preparing polyethylene terephthalate from dimethyl terephthalate and ethylene glycol or terephthalic acid and ethylene glycol by transesterification and polycondensation respectively. The invention further relates to the use of aluminium hydroxide and/or aluminium acetate in combination with at least one phosphoric or phosphonic ester as polymerization catalyst when preparing polyesters by polycondensation or transesterification. (FIG. nil)