A kind of biaxially stretched stereocomposite polylactic acid film and preparation method thereof
A technology of polylactic acid film and biaxial stretching, which is applied in the field of biaxially stretched stereocomposite polylactic acid film and its preparation, can solve the problems of low stereocomposite crystallinity, affecting the heat resistance and mechanical strength of products, and achieve The effect of high production efficiency, large-scale industrial production and good market prospects
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[0040] The present invention also provides a preparation method of a biaxially stretched stereocomposite polylactic acid film, comprising the following steps:
[0041] a) Melt blending 50 parts by weight of L-polylactic acid, 50 parts by weight of D-polylactic acid, 15-30 parts by weight of a compatible blend and 0.5-5 parts by weight of an anti-blocking agent, and cooling to obtain a polymer with an amorphous structure Lactic acid blends;
[0042] The compatible blend includes polyvinyl acetate and / or poly(raclactic acid);
[0043] b) biaxially stretching the polylactic acid blend to obtain a biaxially stretched stereocomplex polylactic acid film.
[0044] In the preparation method provided by the present invention, firstly, the raw materials are melt-blended in proportion. Wherein, the raw material includes L-polylactic acid, D-polylactic acid, compatible blend and anti-blocking agent, preferably also includes anti-hydrolysis agent and / or chain extender; the L-polylactic a...
Embodiment 1
[0060] Weigh 50 parts by weight of L-polylactic acid (weight average molecular weight 500,000, optical purity 96%), 50 parts by weight D-polylactic acid (weight average molecular weight 500,000, optical purity 98%), polyvinyl acetate (weight average molecular weight 15 10,000) 30 parts by weight, 0.1 part by weight of carbodiimide, 0.1 part by weight of pyromellitic dianhydride, 0.5 part by weight of silica (particle size 0.01 μm); then all the above-mentioned raw materials were vacuum-dried at 80° C. for 48 hours , followed by high-speed blending at room temperature for 8 minutes, and then the mixture was added to the twin-screw extruder. The operating temperature of the twin-screw extruder was 220 to 250 ° C, the screw speed was 50 rev / min, and the mixture was in the twin-screw extruder. The residence time in the extruder was 0.5 min; finally, the melt extruded by the twin-screw extruder was casted by a casting roll with a diameter of 1000 mm and a temperature of 25° C. to ob...
Embodiment 2
[0063] Weigh 50 parts by weight of L-polylactic acid (weight average molecular weight 150,000, optical purity 95%), 50 parts by weight D-polylactic acid (weight average molecular weight 150,000, optical purity 99%), polyracemic lactic acid (weight average molecular weight 3 10,000) 15 parts by weight, 1 part by weight of carbodiimide, 1 part by weight of trimellitic anhydride, and 5 parts by weight of calcium carbonate (particle size 10 μm); then all the above-mentioned raw materials are vacuum-dried at 80 ° C for 48 hours, then at normal temperature at high speed After blending for 8 minutes, the mixture was added to the twin-screw extruder. The operating temperature of the twin-screw extruder was 220 to 250°C, and the screw speed was 200 rpm. The residence of the mixture in the twin-screw extruder The time was 2 min; finally, the melt extruded by the twin-screw extruder was casted by a casting roll with a diameter of 1000 mm and a temperature of 45° C. to obtain a polylactic ...
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