Polymerization catalysts for polyesters

摘要

The invention provides non-antimony containing polymerization catalysts for the condensation of polyesters. The catalyst is in the form of a clear chlorine and/or bromine containing solution of a metal glycoxide and a metal glycolate having a pH in the range of from 0 to about 1, and containing chlorine and/or bromine atoms at a number ratio of chlorine and/or bromine to total metal cations in the catalyst ranging from about 0.5:1 to about 3:1. Polyesters produced with this catalyst have improved melt elasticity, and higher melt viscosity. The former property is desirable for the preparation of large and complex shaped polyester containers, and the latter property is desirable for melt spinning of industrial grade fibers and tire cords.