Polyolefin microporous membrane, production method therefor, and battery separator
AssigneeToray Industries, Inc.
InventorsToshihiko KANEDA, Go SATO, Koichi KONO
Life of this patent
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Abstract
A polyolefin microporous membrane is disclosed. The membrane includes a polyolefin resin having an MFR value of not greater than 2.0 g/10 min, and a crystal nucleating agent. The polyolefin microporous membrane has an air permeation resistance scaled to a thickness of 20 μm of from 100 to 500 sec/100 cc, a porosity of from 20% to 60%, and a mean flow pore size of not greater than 100 nm.
Claims10
A polyolefin microporous membrane, comprising:
- a polyolefin resin having an MFR value of not greater than 2.0 g/10 min;
- and
- a crystal nucleating agent,
- wherein the polyolefin microporous membrane has an air permeation resistance scaled to a thickness of 20 μm of from 100 to 500 sec/100 cc, a porosity of from 20% to 60%, and a mean flow pore size of not greater than 100 nm.
A battery separator, comprising:
- a polyolefin microporous membrane, comprising:
- a polyolefin resin having an MFR value of not greater than 2.0 g/10 min;
- and
- a crystal nucleating agent,
- wherein the polyolefin microporous membrane has an air permeation resistance scaled to a thickness of 20 μm of from 100 to 500 sec/100 cc, a porosity of from 20% to 60%, and a mean flow pore size of not greater than 100 nm.
A rechargeable battery, comprising:
- a battery separator, comprising:
- a polyolefin microporous membrane, comprising:
- a polyolefin resin having an MFR value of not greater than 2.0 g/10 min;
- and
- a crystal nucleating agent,
- wherein the polyolefin microporous membrane has an air permeation resistance scaled to a thickness of 20 μm of from 100 to 500 sec/100 cc, a porosity of from 20% to 60%, and a mean flow pore size of not greater than 100 nm.
A method of producing a polyolefin microporous membrane, the polyolefin microporous membrane having an air permeation resistance scaled to 20 μm of from 100 to 500 sec/100 cc, a porosity of from 20% to 60%, and a mean flow pore size of not greater than 100 nm, the method comprising:
- melt-kneading a polyolefin resin, a crystal nucleating agent, and a membrane formation solvent to form a polyolefin resin composition;
- extruding and cooling the polyolefin resin composition to form a gel sheet;
- performing a first stretching step of stretching the gel sheet;
- removing the membrane formation solvent from the gel sheet after stretching;
- and
- drying the sheet after removing the membrane formation solvent.
Dependencies are inferred from the claim text.