METHOD FOR RECOVERING LACTIDE FROM POLYLACTIC ACID PRODUCT

摘要

PURPOSE:To recover a lactide useful for a monomer for polymerization raw material from a polylactic acid product in a short time, in high yield at low cost by heating and blending the polylactic acid product by a screw type extruder in the presence of water and a catalyst at a specific temperature. CONSTITUTION:(A) A polylactic acid product such as filmy sheet or hollow container obtained from a cyclic dimer such as lactic acid or a lactide as a raw material is heated and blended by a screw type extruder in the presence of (B) water and (C) a catalyst such a an alkylaluminum, zinc oxide or manganese acetate at 200-400 deg.C hydrolyzed and depolymerized to recover the objective lactide from the component A. The amounts of the components B and C used are preferably 0.1-5.0 pts.wt. of the component B and 0.1-1.0wt.% of the component C based on the amount of the component A.