METHOD FOR PREPARING POLYLACTIC ACID

摘要

Provided is a method for preparing a polylactic acid, the method comprising: a polymerizing step for adding phenol having steric hindrance at the time point when monomers remaining after the polymerization of lactide or lactic acid is 1-8 mol% relative to the entire monomers, followed by an additional reaction, thereby obtaining a polymer; a cooling step for obtaining pellets from the polymer; and a remaining monomer removing step for introducing an inert gas into a reactor containing the pellets therein at a rate of 0.001-0.5 L/min·g while heating. According to the method for preparing a polylactic acid, high-quality polylactic acid can be provided by minimizing changes in physical properties of the polylactic acid and effectively removing the remaining monomers.