Laminated porous membrane, process for manufacturing same and separator for battery

Patent metadata

Field	Value
Publication number	US-2016276642-A1
Application number	US-201414777572-A
Country	US
Kind code	A1
Filing date	Apr 7, 2014
Priority date	Apr 22, 2013
Publication date	Sep 22, 2016
Grant date	—

Abstract

A laminated porous membrane includes a polyolefin porous membrane, on one surface of which projections that are made of a polyolefin and satisfy 5 μm≦W≦50 μm (W: projection size) and 0.5 μm≦H (H: projection height) are irregularly scattered at a density of 3/cm 2 to 200/cm 2 , and a modifying porous layer laminated on the surface of the polyolefin porous membrane having the projections, wherein the modifying porous layer includes a binder with a tensile strength of at least 5 N/mm 2 and inorganic particles.

First claim

1 - 6 . (canceled)

7 . A laminated porous membrane, comprising:
a polyolefin porous membrane, on one surface of which projections that are made of a polyolefin and satisfy 5 μm≦W≦50 μm (W: projection size) and 0.5 μm≦H (H: projection height) are irregularly scattered at a density of 3/cm 2 to 200/cm 2 , and; a modifying porous layer laminated on the surface of the polyolefin porous membrane having the projections, wherein the modifying porous layer comprises a binder with a tensile strength of at least 5 N/mm 2 and inorganic particles.

8 . The laminated porous membrane according to claim 7 , wherein the binder is polyvinyl alcohol or an acrylic resin.

9 . The laminated porous membrane according to claim 7 , wherein the inorganic particles comprise at least one selected from the group consisting of calcium carbonate, alumina, titania, barium sulfate, and boehmite.

10 . A battery separator comprising the laminated porous membrane according to claim 7 .

11 . A method of producing the laminated porous membrane according to claim 7 , comprising:
(a) adding a molding solvent to a polyethylene resin, and then performing melt blending to prepare a polyethylene resin solution; (b) extruding the polyethylene resin solution through a die, and cooling the extruded polyethylene resin solution with a chill roll having a surface from which the molding solvent has been removed to form a gel-like molding; (c) stretching the gel-like molding in the machine direction and the transverse direction to provide a stretched molding; (d) extracting the molding solvent away from the stretched molding, followed by drying to provide a porous molding; (e) heat-treating the porous molding to provide a polyolefin porous membrane; and (f) forming a laminated membrane on a surface that has been in contact with the chill roll using a coating liquid comprising a binder with a tensile strength of at least 5 N/mm 2 , inorganic particles, and a solvent that is capable of dissolving or dispersing the binder, followed by drying.

12 . The method of producing the laminated porous membrane according to claim 11 , wherein the means for removing the molding solvent in the step (b) is a doctor blade.

13 . The laminated porous membrane according to claim 8 , wherein the inorganic particles comprise at least one selected from the group consisting of calcium carbonate, alumina, titania, barium sulfate, and boehmite.

14 . A battery separator comprising the laminated porous membrane according to claim 8 .

15 . A battery separator comprising the laminated porous membrane according to claim 9 .

16 . A method of producing the laminated porous membrane according to claim 8 , comprising:
(a) adding a molding solvent to a polyethylene resin, and then performing melt blending to prepare a polyethylene resin solution; (b) extruding the polyethylene resin solution through a die, and cooling the extruded polyethylene resin solution with a chill roll having a surface from which the molding solvent has been removed to form a gel-like molding; (c) stretching the gel-like molding in the machine direction and the transverse direction to provide a stretched molding; (d) extracting the molding solvent away from the stretched molding, followed by drying to provide a porous molding; (e) heat-treating the porous molding to provide a polyolefin porous membrane; and (f) forming a laminated membrane on a surface that has been in contact with the chill roll using a coating liquid comprising a binder with a tensile strength of at least 5 N/mm 2 , inorganic particles, and a solvent that is capable of dissolving or dispersing the binder, followed by drying.

17 . A method of producing the laminated porous membrane according to claim 9 , comprising:
(a) adding a molding solvent to a polyethylene resin, and then performing melt blending to prepare a polyethylene resin solution; (b) extruding the polyethylene resin solution through a die, and cooling the extruded polyethylene resin solution with a chill roll having a surface from which the molding solvent has been removed to form a gel-like molding; (c) stretching the gel-like molding in the machine direction and the transverse direction to provide a stretched molding; (d) extracting the molding solvent away from the stretched molding, followed by drying to provide a porous molding; (e) heat-treating the porous molding to provide a polyolefin porous membrane; and (f) forming a laminated membrane on a surface that has been in contact with the chill roll using a coating liquid comprising a binder with a tensile strength of at least 5 N/mm 2 , inorganic particles, and a solvent that is capable of dissolving or dispersing the binder, followed by drying.

Assignees

• Toray Battery Separator Film

Inventors

• Mizuno Naoki
• Matano Koichi
• Shimizu Ken

Classifications

• B32B27/00 Primary

  Layered products comprising {a layer of} synthetic resin {(fibrous or filamentary layer made of a synthetic resin B32B5/02; particulate layer made of a synthetic resin B32B5/16; foamed layer made of a synthetic resin B32B5/18)} · CPC title

• H01M50/417

  Polyolefins · CPC title

• H01M50/406

  Moulding; Embossing; Cutting · CPC title

• H01M50/449

  having a layered structure · CPC title

• H01M2/1653

  Electricity · mapped topic