AN EFFICIENT PROCESS FOR THE PRODUCTION OF HIGH MOLECULAR WEIGHT POLYESTER FROM LOW MOLECULAR WEIGHT PREPOLYMER

摘要

The present invention discloses an efficient process for the production of high molecular weight polyester resin having IV of about 0.5 dl/g to about 1.2 dl/g from low molecular weight prepolymer having IV of about 0.2 dl/g to about 0.45 dl/g by adding the alkali metal salts of Lewis acid such as sulfonic acid selected from sodium para-toluenesulfonate or potassium para-toluene sulfonate at any steps during the esterification or the melt polymerization but before a particle former process. The process reduces the oligomer volatilization during melt polymerization and solid state polymerization and also increases the rate of polymerization and solid state polymerization. The present invention also discloses a low molecular weight crystalline prepolymer having IV of about 0.2 dl/g to about 0.45 dl/g and high molecular weight polyester resin having IV of about 0.5 dl/g to about 1.2 dl/g produced by the above process.