POLYLACTIC ACID AND METHOD FOR PRODUCING THE SAME.

摘要

Disclosed is a method for producing a stereocomplex polylactic acid having high melting point and high molecular weight, wherein only stereocomplex crystals are grown when melting and crystallization are repeated. Specifically disclosed is a method for producing a polylactic acid, which comprises a step (1) for obtaining a first polylactic acid by ring-opening polymerization of a first lactide composed of lactic acid units of the same chirality; a step (2) for obtaining a purified first polylactic acid by removing the lactide from the first polylactic acid in a molten state under a reduced pressure; a step (3) for obtaining a second polylactic acid by ring-opening polymerization of a second lactide having a chirality different from that of the first lactide in the presence of the purified first polylactic acid; and a step (4) for obtaining a purified second polylactic acid by removing the lactide from the second polylactic acid in a molten state under a reduced pressure.