Patent ID: 9637587
Date: 2017-05-02
CPC Classifications: B01D,C07D,C08F,C08G,C08L

Claim:
1. An apparatus for preparing polylactic acid, comprising: a polymerization reactor adapted for performing a ring opening polymerization to obtain a raw polylactic acid having a Mw of at least 20,000 g/mol, a devolatization apparatus adapted for separating low boiling compounds comprising lactide and impurities from the raw polylactic acid having a Mw of at least 20,000 g/mol, a crystallization apparatus for purifying lactide from the low boiling compounds separated in the devolatization apparatus and removing impurities by means of a desublimation and a crystallization in the same crystallization apparatus, and a recycle line connecting the crystallization apparatus and the polymerization reactor for recycling purified lactide from the crystallization apparatus back into the polymerization reactor wherein: