SOLID STATE POLYMERIZATION PROCESS FOR POLYESTER WITH PHOSPHINIC ACID COMPOUNDS

摘要

Disclosed is a method for increasing the solid state polymerization (SSP) rates of metal catalyzed polyesters. The method comprises in a first step, reacting a dicarboxylic acid or a C1-C4 dicarboxylic diester with a diol at a suitable temperature and pressure to effect esterification or transesterification to prepare a precondensate and in a second step, reacting the precondensate to effect polycondensation at a suitable temperature and pressure to prepare a high molecular weight polyester and in a third step, further increasing the molecular weight and viscosity of the polyester under SSP conditions of a suitable temperature and pressure, where a metal catalyst is added in the first step or in the second step as a reaction catalyst, and where a certain phosphinic acid compound is added in the first step, in the second step or just prior to the third step. The polyester product exhibits low aldehyde formation during melt processing steps as well as excellent color.