Method for production of a high molecular weight polyester prepared from a prepolymer polyester having an optimal carboxyl content

摘要

A high molecular weight polyester is produced by a two stage process: a partial melt process until the intrinsic viscosity of the polyester prepolymer reaches from about 0.35 to about 0.62 dl/g, and a solid state polymerization in a static bed until the intrinsic viscosity of the polycondensed polymer reaches at least 0.70 dl/g. The melt process employs greater concentrations of initial acid in combination with a heel or the addition of make-up acid to achieve optimal carboxyl content for the polyester prepolymer capable of use in the static bed solid state polymerization. This prepolymer with an optimal carboxyl content achieves a maximum solid state polymerization rate in a static bed. The production of the high molecular weight polyester by the two stage process minimizes chemical instability and deleterious polymerization byproducts.