PROCESS FOR PRODUCING LACTIDE AND PROCESS FOR PRODUCING POLYLACTIC ACID FROM FERMENTED LACTIC ACID EMPLOYED AS STARTING MATERIAL

摘要

A process for consistently producing lactide from ammonium lactate obtained by lactic acid fermentation; and a process for consistently producing polylacti c acid from ammonium lactate obtained by lactic acid fermentation are provided . Namely, a process for producing lactide which comprises: (1) synthesizing a lactic acid ester from ammonium lactate obtained by lactic acid fermentation ; (2) polycondensing this lactic acid ester in the presence of a catalyst othe r than monobutyl tin to synthesize polylactic acid (a lactic acid prepolymer) having a weight-average molecular weight less than 15,000; and (3) depolymerizing this polylactic acid to give lactide; and a process for producing polylactic acid which further involves (4) ring-opening polymerizi ng the lactide to give polylactic acid. A process for producing a lactic acid ester from ammonium lactate obtained by lactic acid fermentation.