METHOD OF OBTAINING LACTIC ACID, METHOD OF OBTAINING LACTIDE AND METHODS OF OBTAINING POLYLACTIC ACID Russian patent published in 2016 - IPC C12P7/56 B01D61/58 C07C51/42 C07C51/44 C08G63/08 

FIELD: chemistry.

SUBSTANCE: group of inventions relates to biotechnology. Claimed are methods of obtaining lactic acid, obtaining lactide and obtaining polylactic acid. Continuous fermentation of microorganism, possessing ability of lactic acid fermentation, is realised. After that, fermentation medium is filtered through membrane with average pore diameter from 0.01 mcm to 1 mcm with difference of trans-membrane pressure from 0.1 to 20 kPa. Filtrate is collected with preservation of non-filtered liquid in culture medium or return of non-filtered liquid into culture medium and addition of raw material for fermentation to culture medium. Obtained filtrate is filtered through nano-filtration membrane. Distillation of obtained filtrate is realised at pressure from 10 Pa to 30 kPa and temperature from 25°C to 200°C to extract lactic acid. Lactic acid, obtained by claimed method, is catalytically converted into lactide or into polylactic acid by direct dehydration polycondensation.

EFFECT: inventions make it possible to obtain lactic acid with optic purity to 99% and output to 60-92% and obtain polylactic acid with improved thermal stability, mechanical strength and colour.

10 cl, 4 dwg, 6 tbl, 25 ex