| abstract |
(57) Abstract: In a method for producing polylactic acid from a lactic acid monomer by a direct polycondensation method, first, water, lactide, a low-molecular compound of lactic acid and optionally a solvent generated from a reaction vessel are refluxed, Melt polymerization is performed while removing water outside the reaction system, and then the obtained polylactic acid is heated at a temperature equal to or lower than its melting point. A method and an apparatus for producing polylactic acid, wherein solid-state polymerization is performed. [Effect] High-molecular-weight polylactic acid can be industrially advantageously produced. |