Process of making porous films or sheets
AssigneeMitsubishi Chemical Corporation
InventorsToshio Fujii, Keishin Handa, Kyosuke Watanabe
Life of this patent
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Abstract
A porous film or sheet including a resin composition mainly of an ultra-high molecular weight polyethylene having a viscosity-average molecular weight of not less than 500,000, and having a thickness of 10 to 100 .mu.m, an air permeability of 20 to 2,000 sec/100 cc, a porosity of 15 to 80%, a pin puncture strength (per 25 .mu.m of film thickness) of not less than 120 g, a thermal-shut down temperature of 90.degree. to 150.degree. C. and a heat puncture temperature of not less than 160.degree. C., and a process for producing the same.
Claims9
A process for producing a porous film or sheet, which process comprises the steps of melt-extruding a composition consisting essentially of an ultra-high molecular weight polyethylene having a viscosity-average molecular weight of 500,000 to 4,000,000 and a plasticizer thereby forming a film or sheet, giving a deforming stress to the film or sheet to effectuate melt-draft, and after cooling, removing the plasticizer from the obtained film or sheet.
A process for producing a porous film or sheet having a porosity of 30 to 50%, which process comprises the steps of melt-extruding a composition consisting essentially of an ultra-high molecular weight polyethylene having a viscosity-average molecular weight of 500,000 to 4,000,000 and a plasticizer thereby forming a film or sheet, giving a deforming stress thereto to effectuate melt-draft, and after cooling, removing the plasticizer from the obtained film or sheet.
A process for producing a porous film or sheet, which comprises the steps of:
- (a) melt-extruding a composition consisting essentially of an ultra-high molecular weight polyethylene having a viscosity-average molecular weight in a range of 500,000 to 4,000,000 and a plasticizer into a film or a sheet;
- (b) applying a deforming stress to the extruded film or sheet while in a molten state to effectuate melt-drafting;
- (c) cooling;
- and thereafter
- (d) removing the plasticizer for the resulting film or sheet.
Dependencies are inferred from the claim text.