Preparation of a high molecular weight polylactic acid lactide method

The present invention provides a process for preparing a high molecular weight lactide polylactic acid, comprising the steps of: under vacuum conditions, high molecular weight poly lactic acid of the polylactic acid cleavage reaction in the catalyst, resulting lactide; polylactic acid solvent solution comprising a C2 ~ C20 polyol, number average molecular weight of 200 ~ 20000g / mol of polyether ether compound of C10 ~ C30, lactide, number average molecular weight of 200 ~ 8000g / mol of oligomeric lactic acid thereof, polycarboxylic acid ester compound and an ionic liquid of C8 ~ C30 of one or more; containing catalyst comprising a tin compound and / or titanium-containing compound; cleavage reaction temperature is 180 ~ 240 ℃. The present invention is a high molecular weight polylactic acid as a raw material, the polylactic acid prepared directly into a solution prepared after cleavage lactide, compared with the prior art, mild reaction conditions of this process, and reduces high temperature carbonization racemization of lactide .