POROUS PERMEABLE POLYETHYLENE FILM

摘要

PURPOSE:To obtain the titled porous permeable film having an excellent strength and permeability balance without comparison in the past by using high-molecular weight polyethylene having >=4X10<5> viscosity average mol.wt. CONSTITUTION:High-molecular weight polyethylene having >=4X10<5> viscosity average mol.wt. is used, and <=5mol% copolymerizable constituent can be incorporated. A >=15C aliphatic or alicyclic compd. is added to improve the moldability and drawability, and uniformly mixed to swell the polyethylene. The swollen polyethylene is drawn by >=3X3 times at >=50%/sec drawing velocity at 50-130 deg.C to obtain a thin sheet having <=1mm. thickness. The strength is regulated to >=5kg/mm.<2>, and the permeability coefficient to gaseous nitrogen is regulated to >=1X10<-6>mlcm/sec cm<2>cmHg.