▎ 摘　　要

NOVELTY - High-toughness biaxially oriented polylactic acid film comprises an upper surface layer, a core layer and a lower surface layer. The upper surface layer is composed of 5-30% macromolecule modifier, 68-94.8% polylactic acid resin, 0.1-1% slipping agent and 0.1-1% anti-blocking agent. The core layer is composed of racemic polylactic acid, acrylic acid grafted polylactic acid, lignin grafted polylactic acid, carboxylated nano-cellulose grafted polylactic acid, poly(D-lactide)-caprolactone random copolymer, polylactic acid polyethylene glycol copolymer, polylactic acid copolymer and/or polylactic acid/polybutylene adipate terephthalate blend. The lower surface layer is composed of 5-30% macromolecule modifier, 68-94.8% polylactic acid resin, 0.1-1% slipping agent and 0.1-1% anti-blocking agent. USE - The biaxially oriented polylactic acid film is useful for barrier polylactic acid laminated film (claimed). ADVANTAGE - The biaxially oriented polylactic acid film has high toughness. The barrier polylactic acid laminated film has good transparency and excellent oxygen barrier properties. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) preparing the film, comprising (i) mixing upper surface layer, core layer and lower surface layer, uniformly dispersing by using high-speed mixer, (ii) respectively melting raw materials of upper surface layer, core layer and lower surface layer in three extruders, co-extruding, casting melt through T-shaped mold to chilling roll quenching casting sheet with surface temperature of 15-40 degrees C, (iii) performing transverse and longitudinal synchronous stretching to un-stretched casting sheet at 40-125 degrees C, where stretching multiplying power is 2x 2-4x 4, and (iv) performing heat-setting treatment in film obtained in step (iii) at 50-155 degrees C, performing corona treatment on at least one surface layer of the film, rolling, and cutting to obtain high-toughness biaxially oriented polylactic acid film with thickness of 15-100 mu m; (2) barrier polylactic acid laminated film, comprising a protective coating layer, a barrier evaporation layer, a bottom coating layer and a base film that are orderly provided, where the base film is high-toughness biaxially oriented polylactic acid film; and (3) preparing the barrier polylactic acid laminated film, comprising (i) unreeling base film, coating bottom coating layer on corona treated surface, placing in oven, drying at 60-130 degrees C, rolling, and placing in curing chamber at 40-60 degrees C for curing to obtain polylactic acid film coated with bottom coating layer, and (ii) evaporating barrier layer on bottom coating layer, uniformly coating protective coating layer on surface of coating layer of polylactic acid film with vapor-deposited barrier evaporation layer, drying at constant temperature, drying and coiling coated film to obtain barrier polylactic acid laminated film.