Polyolefin microporous membrane
AssigneeAsahi Kasei Chemicals Corporation
InventorsMasahiro Ohashi, Hiroshi Sogo
Life of this patent
Estimating the term…
Abstract
Disclosed is a polyolefin microporous membrane including a multilayer film having two or more layers. In this polyolefin microporous membrane, at least one surface layer has a thickness of not less than 0.2 μm but not more than 5 μm and contains inorganic particles, while at least one layer contains a polyethylene and has an air permeability of not less than 50 second/100 cc but not more than 1000 second/100 cc and a puncture strength of not less than 3.0 N/20 μm.
Claims10
A polyolefin microporous membrane which comprises a laminated film of three layers made up of an interlayer between two surface layers, wherein each surface layer has a thickness of 1 μm or more and 4 μm or less and contains inorganic particles in an amount of 10% by mass or more and 40% by mass or less and wherein the interlayer contains polyethylene, but no inorganic particles;
- wherein the polyolefin microporous membrane has a gas transmission rate of 50 sec/100 cc or more and 1000 sec/100 cc or less wherein the gas transmission rate is measured in accordance with JIS P-8117 and a piercing strength of 3.0 N/20 μm or more wherein the piercing strength is measured using a needle tip with a radius of curvature of 0.5 mm and a piercing speed of 2 mm/s;
- and wherein the surface layers of the polyolefin micropomus membrane are obtained through a step of kneading a polyolefin resin, the inorganic particles and a plasticizer in the amounts satisfying the following formula (1):
- 0.6<weight of plasticizer/(oil absorption for plasticizer×weight of inorganic particles×density of plasticizer)×100<12, (1);
- and wherein the inorganic particles have an oil absorption for the plasticizer of 150 ml/100 g or more and 1000 ml/100 g or less.
Dependencies are inferred from the claim text.