| 摘要 |
PURPOSE:To obtain an inflation film having a specified property by extruding ultrahigh mol.wt. polyethylene whose uppermost viscosity eta is higher than 15dl/g through a tube die whose L/D is at least 5 and by carrying out thereafter infla tion molding. CONSTITUTION:Ultrahigh mol.wt. polyethylene whose intrinsic viscosity eta is higher than 5dl/g is extruded by a molding machine in which a tube die whose L/D is higher than 5 is directly connected to the top end of the extruder having a screw of low compression ratio and a mandrel of the tube die is directly connected to the top end of the screw of the extruder. A molten tube film having been extruded from the tube die is expanded and cooled by blowing air into the tube. An inflation film of ultrahigh mol.wt. polyethylene whose longitudinal and lateral breaking strengths are higher than 800 and 700kg/cm<2> respectively, impact strength is higher than 5,000kg.cm/cm, humidity transmission coefficient is smaller than 0.45g.mm/m<2>.24hrs, lateral shrinking percentage is higher than 10% and thickness is in the rage of 10-1,000mum can be obtained. |
