Preparation method of polylactic acid film opening master batch

The invention relates to a polylactic acid film opening master batch and a preparation method thereof, alcohol is added as an initiator in the ring-opening polymerization process of lactide to prepare a polylactic acid prepolymer, and a maleic anhydride modified opening agent is added in the polymerization reaction process to carry out multi-stage reaction with lactide to prepare the polylactic acid film opening master batch. The polylactic acid film opening master batch is prepared by blending, granulating and drying a polymerized slipping agent and other auxiliary agents, and can be used for being added into a polylactic acid-based biodegradable film product in a small amount. According to the preparation method, agglomeration of the nano particles is avoided, so that the nano particles are more uniformly dispersed in the opening master batch, adverse effects on appearance and mechanical properties caused by falling of the nano particles on the surface of a polylactic acid-based plastic film are reduced, an