To provide a method for producing a high quality polyhydroxycarboxylic acid in a process capable of massively producing the acid.
This method for producing a polyhydroxycarboxylic acid comprises treating a hydroxycarboxylic acid and/or its oligomer with a haloiminium salt and an organic base to obtain the organic solvent solution of the polyhydroxycarboxylic acid and subsequently adding an aliphatic alcohol to the solution to deposit and isolate the polyhydroxycarboxylic acid. Therein, the solution containing the recovered organic solvent, the aliphatic alcohol, an amide compound and/or a urea compound and/or an imidazolidinone compound produced after the reaction of the haloiminium salt, and the salt of the organic base is thermally treated at a temperature of 160-250°C, distilled out, and subsequently reused, respectively, for the reaction.
KUMAMOTO YUKIHIRO
WATANABE KATSUJI
TAMAI MASAJI
