Procedure as well as device for the preparation of a mixture of crystallizable polylactic acid as well as polylactic acid mixture

摘要

In a practicable continuous or batchwise process for the preparation of a crystallizable polylactic acid mixture, lactic acid may be polycondensed to yield an oligomer, which may then be depolymerized to yield a crude lactide. The crude lactide may be purified to yield a pure lactide, wherein fractionation may be carried out in the purification into an L- or D-lactide-rich fraction and also a meso-lactide-rich fraction. Subsequently a separate ring-opening polymerization of the resulting lactide fractions can be carried out. The individual polylactic acid batches or streams generated by the ring-opening polymerization may then be mixed. The present disclosure further relates to apparatuses for carrying out such processes and polylactic acid mixtures.