PROCESS FOR PRODUCING POLYESTER POLYMER

PURPOSE: Provided is a process for producing a polyester polymer excellent in color and properties, which can shorten the time of esterification and polycondensation, therefore, it can improve productivity. CONSTITUTION: The polyester polymer is produced by esterifying naphthalene dicarboxylic acid(NDCA) or a dicarboxylic acid containing the same as a main component or an ester derivative thereof and ethylene glycol or glycol containing the same as a main component or a derivative thereof and then performing the polycondensation, wherein the process for producing the polyester polymer uses a catalyst produced by reacting a titanium compound and a cobalt compound in the presence of at least one alcohol compound solution. The titanium compound is at least one selected from the group consisting of tetra isopropyl titanate, tetrabutyl titanate, and tetra isopropyl di(dioctyl)phosphito titanate. And the cobalt compound is at least one selected from the group consisting of cobalt acetate, cobalt ethyl hexyl octoate, cobalt nitrate, and cobalt oxalate.