METHOD FOR PREPARING LACTIDE FOR SYNTHESIS OF POLYMER POLY L-LACTIC ACID

摘要

A method for preparing crude lactide is provided to maximize production yield, to minimize racemization and to obtain the lactide of molten state by optimizing the reaction condition. A method for preparing crude lactide comprises the steps of preparing the poly(lactic acid) having a low molecular weight from lactic acid; and reacting the poly(lactic acid) having a low molecular weight in the presence of a catalyst at a high temperature and at a high pressure. Preferably the molecular weight of the poly(lactic acid) having a low molecular weight is 300-5,000 g/mol; and the catalyst is a metal oxide, a metal halide or a metal carboxylate containing a metal selected from the group consisting of Sn, Zn, Fe and Sb.