▎ 摘　　要

NOVELTY - Toughened biaxially oriented polylactic acid film comprises a first surface layer, a core layer and a second surface layer are arranged in sequence. The first surface layer comprises 10-20 wt.% toughening resin, 0.5-3 wt.% nano-inorganic filler, 0.1-1 wt.% anti-blocking agent, 0.1-1 wt.% slip agent, and 75-89.3 wt.% PLLA resin composition. The core layer comprises 10-20 wt.% toughening resin, 0.5-3 wt.% nano-inorganic filler, and 77-89.5 wt.% Poly(L-lactide) (PLLA) resin. The second surface layer comprises 10-20 wt.% toughening resin, 0.5-3 wt.% nano-inorganic filler, 0.1-1 wt.% anti-blocking agent, 0.1-1 wt.% slip agent, and 75-89.3 wt.% PLLA resin composition. The toughening resin comprises polylactic acid stereocomplex and/or copolymer. USE - Used as toughened biaxially oriented polylactic acid film. ADVANTAGE - The toughened biaxially oriented polylactic acid film has excellent mechanical properties, good heat resistance, uniform thickness, degradability, etc., and can be widely used in a variety of flexible packaging fields. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing the toughened biaxially oriented polylactic acid film comprising (i) uniformly mixing raw materials of the first surface layer, the core layer and the second surface layer in a high mixer according to the proportions, (ii) adding the mixture obtained in the step (i) into three extruders respectively, adding mixture of the first surface layer and the second surface layer to the auxiliary extrusion, and adding the mixture of the core layer to the main extrusion, melt co-extrusion, casting the melt through a T-die to a chill roll quenched cast sheet with a surface temperature of 15-50 degrees C, and (iii) subjecting cast thick sheet to humidity conditioning treatment in a water tank at 40-75 degrees C, adjusting the humidity, the surface of the cast thick sheet is blown dry with an air knife, and simultaneously biaxially stretched, during the biaxial stretching of the film, the stretching temperature is 90-150 degrees C, the heat setting temperature is 140-170 degrees C, and the stretching ratio is 2.5x 2.5-3.5x 3.5.