HIGHLY ORIENTED FILM BY COLD DRAWING AND ITS PRODUCTION

摘要

PURPOSE:To obtain a highly oriented flushing film suitable for agricultural and packaging materials, having high strength, by extruding a composition consisting of ethylene-vinyl acetate copolymer, alpha-olefin copolymer, and polyamide, from a die, followed by orientation. CONSTITUTION:A composition consisting of A) ethylene-vinyl acetate copolymer, B) a thermoplastic elastomer made of alpha-olefin copolymer, and C) polyamide is mixed to give a molten blend. The blend is extruded from a die, guenched by a liquid refrigerant, and set to make a raw film, which is heated up to not more than 100 deg.C and oriented in a cold state at 20-100 deg.C at an area draw ratio of 5-30:1 and at a cross direction draw ratio of 2-7:1 to have a reflectance of diffused reflection not less than 30%. A copolymer of A having less than 30 wt. % of vinyl acetate group degrades orientation in a cold state, film strength, and thermal shrinkage, and a copolymer of A having not less than 30 wt. of vinyl acetate group reduces stretchability.