Preparation of polylactic acid

HANZSCH BERND other August 21, 2003 U.S. Patent US 2003 158360, reported a method for preparing Calcium lactate  the following steps: fermentation of starch obtained produce lactic acid, by ultrafiltration, nano filtration and / or electrodialysis ultrapure lactic acid, concentrated acid, to prepare the prepolymer, the ring is double resolve zinc lactate  lactic acid purification double, double ring-opening and deprotection monomeric lactic acid polymer obtained polylactic acid.
SHIMADZU CORP 2002 年 10 月 15 Publication Date of JP 2002 300898, reported a production of lactic acid and polylactic acid. Specific methods: ⑴ synthesis using ammonium lactate lactate; ⑵ butyltin outside in addition to the presence of a catalyst, the polycondensation of lactic acid ester, an average molecular weight less than 15000mol.wt synthesis of polylactic acid (lactic acid prepolymer); ⑶ solution obtained copolymerized lactic acid; the method further comprises ring-opening polymers polylactic acid.