SHRINK RESISTANT MICROPOROUS MEMBRANE AND BATTERY SEPARATOR
A shrink resistant microporous membrane includes a base material composed of a porous membrane, and a surface layer that is formed on at least one surface of the base material, and contains a heat resistant resin, a ceramic, and a clay mineral.
1 . A shrink resistant microporous membrane comprising:
a base material composed of a porous membrane; and
a surface layer that is formed on at least one surface of the base material, and contains a heat resistant resin, a ceramic, and a clay mineral.
2 . The shrink resistant microporous membrane according to claim 1 ,
wherein the clay mineral has a lamellar structure composed by laminating a number of layers.
3 . The shrink resistant microporous membrane according to claim 2 ,
wherein an average particle diameter of the clay mineral dispersed in the surface layer is 1.0 μm or smaller.
4 . The shrink resistant microporous membrane according to claim 3 ,
wherein an aspect ratio of the clay mineral dispersed in the surface layer is 15 or higher.
5 . The shrink resistant microporous membrane according to claim 2 ,
wherein a diffraction intensity with respect to a diffraction angle 2 θ of a 001 face of the clay mineral dispersed in the surface layer, which is measured by an X-ray diffraction method, has no characteristic peak.
6 . The shrink resistant microporous membrane according to claim 5 ,
wherein the clay mineral dispersed in the surface layer is separated into a state in which a single layer or 2 to 4 layers are laminated.
7 . The shrink resistant microporous membrane according to claim 2 ,
wherein the clay mineral is lamellar silicate denatured by an organic modifier.
8 . The shrink resistant microporous membrane according to claim 7 ,
wherein the clay mineral has a polar group.
9 . The shrink resistant microporous membrane according to claim 8 ,
wherein the clay mineral has an alkyl chain.
10 . The shrink resistant microporous membrane according to claim 9 ,
wherein the clay mineral is mica fluoride organically modified by bis(2-hydroxyethyl)methyldodecylammonium ions or bentonite organically modified by oleylbis(2-hydroxyethyl)methylammonium.
11 . The shrink resistant microporous membrane according to claim 2 ,
wherein the clay mineral is included at 1% by weight to 10% by weight with respect to a total weight of the heat resistant resin and the clay mineral.
12 . The shrink resistant microporous membrane according to claim 2 ,
wherein the interlayer distance of the clay mineral before dispersion is 0.9 nm to 1.4 nm.
13 . The shrink resistant microporous membrane according to claim 1 ,
wherein the resin material composing the base material is composed of an olefin-based resin.
14 . The shrink resistant microporous membrane according to claim 1 ,
wherein at least one of a melting point and a glass transition temperature of the heat resistant resin is 180° C. or higher.
15 . The shrink resistant microporous membrane according to claim 14 ,
wherein the heat resistant resin is polyvinylidene fluoride.
16 . The shrink resistant microporous membrane according to claim 1 ,
wherein the surface of the ceramic is basic.
17 . The shrink resistant microporous membrane according to claim 16 ,
wherein the ceramic includes at least alumina (Al 2 O 3 ).
18 . A battery separator comprising:
a base material composed of a porous membrane; and
a surface layer that is formed on at least one surface of the microporous membrane, and contains a heat resistant resin, a ceramic, and a clay mineral.