A sealing member containing a copolymer containing tetrafluoroethylene unit and a perfluoro (propyl vinyl ether) unit, wherein the copolymer has a content of the perfluoro(propyl vinyl ether) unit of 3.0 to 4.5% by mass with respect to the whole of the monomer units, a melt flow rate of 5 to 26 g/10 min, and the number of functional groups of —CF═CF.sub.2, —CF.sub.2H, —COF, —COOH, —COOCH.sub.3, —CONH.sub.2 and —CH.sub.2OH of more than 50 per 10.sup.6 main-chain carbon atoms, wherein the sealing member has a thickness of 0.5 to 2.5 mm. Also disclosed is a power storage assembly including the sealing member.

A sealing member containing a copolymer containing tetrafluoroethylene unit and a perfluoro(propyl vinyl ether) unit, wherein the copolymer has a content of the perfluoro(propyl vinyl ether) unit of 2.7 to 4.5% by mass with respect to the whole of the monomer units, a melt flow rate of 26 to 42 g/10 min, and the number of functional groups of —CF═CF.sub.2, —CF.sub.2H, —COF, —COOH, —COOCH.sub.3, —CONH.sub.2 and —CH.sub.2OH of more than 50 per 10.sup.6 main-chain carbon atoms. Also disclosed is a power storage assembly including the sealing member.

A powdery primer composition, containing a meltable fluororesin powder having an average particle size of 5 to 100 μm; and polyethersulfone powder, wherein the weight ratio between the meltable fluororesin powder and the polyethersulfone powder is 50:50 to 95:5, and the meltable fluororesin has a melt flow rate of 0.1 to 50 g/10 min. Also disclosed is a primer film formed from the powdery primer composition, and a laminate including a film containing a meltable fluororesin provided on the primer film.

A powdery primer composition, containing a meltable fluororesin powder having an average particle size of 5 to 100 μm; and polyethersulfone powder, wherein the weight ratio between the meltable fluororesin powder and the polyethersulfone powder is 50:50 to 95:5, and the meltable fluororesin has a melt flow rate of 0.1 to 50 g/10 min. Also disclosed is a primer film formed from the powdery primer composition, and a laminate including a film containing a meltable fluororesin provided on the primer film.

A meltable fluororesin primer including a tetrafluoroethylene/hexafluoropropylene copolymer (FEP) particles, a heat-resistant resin, a nonionic surfactant, an acetylenic diol-based surfactant and water, wherein: the FEP particles have an average particle size of 10 to 60 μm; the heat-resistant resin is selected from polyamideimide resins, polyethersulfone resins and polyimide resins; the solid content mass ratio between the FEP particles and the heat-resistant resin is 50:50 to 95:5; the nonionic surfactant is a polyoxyethylene alkyl ether surfactant; and the meltable fluororesin primer contains 10 to 60% by mass of water based on the meltable fluororesin primer. Also disclosed is a primer film formed from the meltable fluororesin primer, a laminate including a film containing a meltable perfluoropolymer provided on the primer film, and a coated article including the laminate.

A meltable fluororesin primer including a tetrafluoroethylene/hexafluoropropylene copolymer (FEP) particles, a heat-resistant resin, a nonionic surfactant, an acetylenic diol-based surfactant and water, wherein: the FEP particles have an average particle size of 10 to 60 μm; the heat-resistant resin is selected from polyamideimide resins, polyethersulfone resins and polyimide resins; the solid content mass ratio between the FEP particles and the heat-resistant resin is 50:50 to 95:5; the nonionic surfactant is a polyoxyethylene alkyl ether surfactant; and the meltable fluororesin primer contains 10 to 60% by mass of water based on the meltable fluororesin primer. Also disclosed is a primer film formed from the meltable fluororesin primer, a laminate including a film containing a meltable perfluoropolymer provided on the primer film, and a coated article including the laminate.

A coating composition is used to prepare a separator for a rechargeable lithium battery. The coating composition includes inorganic particles, a binder, a silane-based dispersant, and a polymeric additive, the silane-based dispersant includes a silane-based compound having fewer than 8 carbons in an alkyl main chain, and the polymeric additive includes a fatty acid compound and a polymer polyol. The coating composition may have secured or improved long-term storage stability, and may thus provide for a composite separator having a reduced number of black spot defects after coating the separator.

A coating composition is used to prepare a separator for a rechargeable lithium battery. The coating composition includes inorganic particles, a binder, a silane-based dispersant, and a polymeric additive, the silane-based dispersant includes a silane-based compound having fewer than 8 carbons in an alkyl main chain, and the polymeric additive includes a fatty acid compound and a polymer polyol. The coating composition may have secured or improved long-term storage stability, and may thus provide for a composite separator having a reduced number of black spot defects after coating the separator.

Porous air permeable expanded PTFE composite with enhanced mechanical and thermal properties are described. The node and fibril microstructure of expanded PTFE is coated on and within the node and fibril microstructure with a suitably chosen polymer to impart property enhancement while maintaining porosity. The coating polymer content of the composite is maintained between 3 and 25 weight percent of the composite and the areal mass of the composite is less than 75 gm/m.sup.2. Exemplary enhancement to properties may include, among others, Average Tensile Strength (ATS) (in MPa)×Z strength (in MPa) of 50 MPa.sup.2 or greater, preferably 100 MPa.sup.2 or greater, with air flow less than 500 Gurley seconds. Coating polymers with appropriate temperature resistance provides composites which further exhibit shrinkage of less than 10% at temperatures up to 300° C. with air flow of less than 500 Gurley seconds.

Porous air permeable expanded PTFE composite with enhanced mechanical and thermal properties are described. The node and fibril microstructure of expanded PTFE is coated on and within the node and fibril microstructure with a suitably chosen polymer to impart property enhancement while maintaining porosity. The coating polymer content of the composite is maintained between 3 and 25 weight percent of the composite and the areal mass of the composite is less than 75 gm/m.sup.2. Exemplary enhancement to properties may include, among others, Average Tensile Strength (ATS) (in MPa)×Z strength (in MPa) of 50 MPa.sup.2 or greater, preferably 100 MPa.sup.2 or greater, with air flow less than 500 Gurley seconds. Coating polymers with appropriate temperature resistance provides composites which further exhibit shrinkage of less than 10% at temperatures up to 300° C. with air flow of less than 500 Gurley seconds.