METHOD FOR PREPARING POLYESTER HAVING GOOD TONE OF COLOR AND THERMAL STABILITY

摘要

PURPOSE: A method for preparing polyester having good tone of color and thermal stability and low diethylene glycol content is provided. CONSTITUTION: A method for preparing polyester having good tone of color and thermal stability according to the present invention comprises the steps: a) directly esterifying dicarboxylic acid containing at least 85 mole% of terephthalic acid and glycol containing at least 85 mole% of ethylene glycol to obtain a mixture of bis(2-hydroxyethyl)terephthalate and oligomer thereof; and b) polycondensating the said mixture at reduced pressure to produce polyester wherein a complex obtained from the reaction between lower alkyl phosphate and cobalt compound is added as an additive.