PRODUCTION OF INFLATION FILM AT HIGH SPEED

摘要

PURPOSE:To obtain firm stiffness and high tear strength by setting the shearing speed of a polyolefin resin compsn. consisting of a specific ethylene/alpha-olefin copolymer, low density polyethylene and an anti-block agent at the outlet of a die and the blow ratio of a film to specific values. CONSTITUTION:A polyolefin resin compsn. with density of 0.915-0.925g/cm<3> and a melt flow rate of 0.1-10g/10min is prepared from 70-95wt.% of an ethylene/alpha-olefin copolymer with density of 0.900-0.930g/10min and a melt flow rate of 0.1-10g/10min, 5-30wt.% of low density polyethylene with density of 0.915-0.935g/cm<3> and a melt flow rate of 0.1-10g/10min and 0.005-2wt.% of an anti-block agent and cooled from the inside and outside of a die. This resin compsn. is formed into a film under such a condition that the length from the outlet of the die to a frost line is set to 3-7 times the diameter of the die and the shearing speed of the resin at the outlet of the die is set to at least 80sec<-1> and a blow ratio is set to 2.0 or more.