- PREPARATION METHOD OF POLYLACTIC ACID BY ONE-POT DIRECT POLYCONDENSATION

摘要

The present invention relates to a method for producing polylactic acid, which comprises one-port direct polymerization comprising lactic acid selected from L-lactic acid, D-lactic acid or a mixture thereof in a screw polymerization reactor, and specifically, to a method for producing polylactic acid, in which the one-port direct polymerization comprises a melt polymerization step, a half crystallization step and a solid phase polymerization step, and the polylactic acid is dehydrated by high-temperature decompression with a vacuum pump during the one-port direct polymerization. It is an object of the present invention to provide the polylactic acid having a high molecular weight by performing polymerization with a single polymerization reactor without intermediate purification, recovery and grinding steps of lactic acid by the one-port direct polymerization.