Abstract: This invention is related to a process for preparing polyester polymers using a composite catalyst comprises the steps of 1) esterifying naphthalene dicarboxylic acid or a dicarboxylic acids containing NDCA or ester derivatives thereof, with ethylene glycol or glycols containing ethylene glycol or derivatives thereof to produce esterified compounds or its low molecular weight polymers; and then 2) continuously polycondensing the obtained esterification product to produce polyester polymers; and wherein the process includes using a composite polymerization catalyst which was prepared by reacting titanium compounds and cobalt compounds in the solution containing at least one alcohol. The process yields high quality polyester polymers having a good color and excellent physical properties. The process can considerably reduce both the esterification time and the polycondensation time.

Abstract: The present invention relates to a process of preparing polycarbonates, more specifically to a process of preparing polycarbonates by solid state polymerization using microwave radiation, which comprises steps of preparing polycarbonate prepolymer having a certain range of viscosity average molecular weight; converting said polycarbonate prepolymer into crystalline particles having a certain degree of crystallinity; and producing polycarbonates by solid state polymerization of said crystalline particles by applying microwave radiation, thus resulting in production of high quality polycarbonates with high molecular weight within short time.