| 摘要 |
PURPOSE:To obtain a microporous polyethylene membrane having high efficiency for removing submicron particles by forming a sheet from a composition consisting of polyethylene with a specific molecular weight and a plasticizer by melt-extrusion and drawing the sheet after the plasticizer is removed. CONSTITUTION:A sheet is obtained by melt-extrusion of a composition consisting of polyethylene with 8X10<5>-3X10<6> of weight average molecular weight and a plasticizer and then the plasticizer is removed from the sheet and the resulting porous sheet is drawn to 2-6 time length to the longitudinal direction at 90-120 deg.C by a roll drawing machine and further drawn to 3-8 times to the transverse direction at 110-130 deg.C by a tenter drawing machine. By this method, a microporous polyethylene membrane which is polyethylene with 8X10<5>-3X10<6> of average molecular weight and has 5-25mum thickness, >=3000L/H.m<2>.atm of water permeation speed, and >=95% of blocking efficiency for 0.091mum styrene latex particles is obtained. The microporous membrane is especially useful as a filtration membrane with high efficiency for removing submicron particles and high treatment speed. |
