METHOD FOR OBTAINING POLYHYDROXYCARBOXYLIC ACID Russian patent published in 2016 - IPC C08G63/08 B01D7/00 B01D7/02 B01D9/00 B01D9/02 B01D9/04 

FIELD: chemistry.

SUBSTANCE: invention relates to method for obtaining polylactic acid. Method for obtaining polylactic acid includes the following stages: (i) realisation of polymerisation with cycle opening, with application of catalyst, and either catalyst deactivator, or additive, blocking terminal groups, to obtain non-purified polylactic acid with molecular weight higher than 10000 g/mol, (ii) purification of polylactic acid by removal and separation of low-boiling compounds, including lactide and admixtures, from non-purified polylactic acid by removal of volatile low-boiling compounds in form of gas-phase flow, (iii) purification of lactide at stage of removal of volatile components and removal of admixtures from gas-phase flow of evaporated low-boiling compounds by means of crystallisation by desublimation from gas-phase, in which lactide is purified, and removed admixtures include catalyst residue and compound, containing at least one hydroxyl group, with thereof purified lactide being further polymerised by supplying it back into polymerisation with cycle opening. Device for method realisation is also claimed.

EFFECT: simplification of technology.

25 cl, 10 dwg, 2 tbl, 2 ex