| 摘要 |
PURPOSE:To enhance the tear strengths in the machine direction (MD) and in the transverse direction (TD) of sheet or film without impairing mechanical performances and the like by a method wherein the sheet or film is longitudinally uniaxially stretched under specified conditions so as to have the Elmendorf tear strengths in MD and in TD of 60kg/cm and above after stretched. CONSTITUTION:Ethylene-alpha-olefin copolymer, which substantially has no long branched chain and the density of which is 0.91-0.94, is made in a form of sheet or film and then formed in an uniaxially stretched sheet or film by stretching 2 or more times longitudinally uniaxially without exceeding 5% in neck-in rate. The Elmendorf tear strengths of the resultant molded product must be 60kg/cm and above in MD and TD. Said ethylene-alpha-olefin copolymer having substantially no long branched chain can be obtained by copolymizing ethylene and alpha-olefin under moderate pressure with transition-metal catalyst. Furthermore, longitudinal uniaxial stretching can be preformed by applying roll stretching, rolling or the like. |
