Items include polylactic acid

BRUSSELS BIOTECH (BE) 2004 年 2 月 13 Publication Date of World Patent WO 2004 014889, reported Ethyl lactate  its independence items include the following: ⑴ lactic acid was prepared as follows: (a) evaporation of lactic acid or lactic acid derivatives a molecular weight of 400-2000 solution preparation, the total acidity of lactic acid equivalent 119-124.5%, optical purity equal to 90-100% L-polylactic acid oligomers; (b) the oligomer depolymerization catalyst is added to the depolymerization reaction is prepared to give a lactic acid-rich gas phase and a liquid phase rich  calcium lactate  (c) condensing vapor to obtain a liquid crude acid; (d) extracting the crude acid crystals; (e) separation and to obtain a rich exhaust crystals lactic acid crystals wet cake; (f) drying the wet cake to obtain pre-purification of lactic acid; and (g) pre-purification of lactic acid obtained crystalline residue acidity than 10meq/kg, the water content of less than 200ppm and meso-lactic acid content of less than 1% purification of lactic acid; ⑵ polymer obtained above polylactic acid was obtained.