A material for a printed circuit board, which is a film composed of a fluorinated resin layer, where the fluorinated resin layer contains a composition containing a fluorinated copolymer having at least one functional group selected from a carbonyl group-containing group, a hydroxy group, an epoxy group and an isocyanate group, has a melt flow rate of at most 15 g/10 min measured at 372 C. under a load of 49N, and has a storage elastic modulus of at least 650 MPa.

To provide an ETFE film which is unlikely to wrinkle when stretched and retracted, and a method for producing the same. It is an ethylene-tetrafluoroethylene copolymer film characterized in that the crystallinity obtained by the formula (1) from the peak area S.sub.20 in the vicinity of 2=20, the peak area S.sub.19 in the vicinity of 2=19 and the peak area S.sub.17 in the vicinity of 2=17 in the diffraction intensity curve obtained by the X-ray diffraction method, is from 55 to 70%, and the proportion of the quasi-crystal layer obtained by the formula (2) is from 10 to 20%:
crystallinity (%)=(S.sub.19+S.sub.2)/(S.sub.17+S.sub.19+S.sub.20)100(1)
proportion of quasi-crystal layer (%)=S.sub.20/(S.sub.17+S.sub.19++S.sub.20)100(2).

To provide an ETFE film which is unlikely to wrinkle when stretched and retracted, and a method for producing the same. It is an ethylene-tetrafluoroethylene copolymer film characterized in that the crystallinity obtained by the formula (1) from the peak area S.sub.20 in the vicinity of 2=20, the peak area S.sub.19 in the vicinity of 2=19 and the peak area S.sub.17 in the vicinity of 2=17 in the diffraction intensity curve obtained by the X-ray diffraction method, is from 55 to 70%, and the proportion of the quasi-crystal layer obtained by the formula (2) is from 10 to 20%:
crystallinity (%)=(S.sub.19+S.sub.2)/(S.sub.17+S.sub.19+S.sub.20)100(1)
proportion of quasi-crystal layer (%)=S.sub.20/(S.sub.17+S.sub.19++S.sub.20)100(2).

The present invention relates to a method of producing a polymer including: polymerizing a compound represented by the following formula (3); or copolymerizing the compound represented by the following formula (3) with a compound (6) having a reactive carbon-carbon double bond and differing from the compound represented by the following formula (3), in a presence of at least one compound selected from the group consisting of compounds represented by the following formula (1) and compounds represented by the following formula (2).

To provide a secondary battery having excellent charge-discharge cycle characteristics (capacity retention rate) and discharge rate characteristics (discharge capacity ratio), as well as a primer for a power storage device electrode, a composition for forming a primer layer and an electrode for a power storage device, to obtain such a secondary battery. A primer for a power storage device electrode, to form a primer layer between a current collector and an electrode active material layer, said primer for a power storage device electrode, containing a fluorinated copolymer which has units based on tetrafluoroethylene or chlorotrifluoroethylene and units based on ethylene, hexafluoropropylene or a perfluoro(alkyl vinyl ether), but does not substantially have units based on vinylidene fluoride, and which has adhesive functional groups that can react with hydroxy groups or can form hydrogen bonds.

A molded article containing a crystal of a fluoropolymer. The fluoropolymer contains at least one selected from vinylidene fluoride/tetrafluoroethylene copolymer, polychlorotrifluoroethylene, an ethylene/tetrafluoroethylene copolymer, a tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer and a tetrafluoroethylene/hexafluoropropylene copolymer. Further, the crystal is a nano-oriented crystal having a size of 300 nm or smaller.

A molded article containing a crystal of a fluoropolymer. The fluoropolymer contains at least one selected from vinylidene fluoride/tetrafluoroethylene copolymer, polychlorotrifluoroethylene, an ethylene/tetrafluoroethylene copolymer, a tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer and a tetrafluoroethylene/hexafluoropropylene copolymer. Further, the crystal is a nano-oriented crystal having a size of 300 nm or smaller.

To provide a dispersion, a laminate, a film and an impregnated woven fabric.

A powder dispersion comprising powder I of polymer I having units based on tetrafluoroethylene and an oxygen-containing polar group, powder II of polymer II containing units based on a fluoroolefin, a dispersing agent, and a liquid dispersion medium, wherein the ratio of the mass content of the polymer I to the mass content of the polymer II is at most 0.7, or such a power dispersion wherein the dispersing agent is a fluorinated surfactant having a hydroxy group. A laminate, a film, and an impregnated woven fabric produced by using such a powder dispersion.

An insulated electric wire is composed of a conductor, and an insulating layer disposed around an outer circumference of the conductor. The insulating layer is formed from a fluorine-containing elastomer composition, and the fluorine-containing elastomer composition includes a base polymer (A) including 70% by mass or more and 98% by mass or less of a copolymer (a1) of tetrafluoroethylene and an -olefin having 2 to 4 carbon atoms, and 2% by mass or more and 30% by mass or less of an ethylene-ethyl acrylate copolymer (a2) (excluding an ethylene-ethyl acrylate-maleic anhydride ternary copolymer), and a flame retardant (B) including an antimony compound (b1) and a bromine-based flame retardant (b2), and including 1 part by mass or more and 9 parts by mass or less of the antimony compound (b1), and 0.3 parts by mass or more and 15 parts by mass or less of the bromine-based flame retardant (b2) per 100 parts by mass of the base polymer (A).

To provide a method for producing modified polytetrafluoroethylene, in which formation of a fluorinated oligomer as a by-product is little. A method for producing modified polytetrafluoroethylene which contains substantially no C.sub.6-34 fluorinated oligomer containing hydrophilic functional groups and which contains substantially no fluorinated surfactant, the method comprising conducting copolymerization of tetrafluoroethylene and a monomer having a polar group, in a liquid dispersion 1 comprising a polymer containing units derived from a non-fluorinated monomer and an aqueous medium, or in a solution 2 obtainable by mixing at least one member selected from the group consisting of a polyalkylene oxide compound and a hydrocarbon-containing surfactant, with an oxidizing agent, in an aqueous medium, under such a condition that the amount of the monomer having a polar group to be used, is at most 0.150 mass % to the whole amount of tetrafluoroethylene, to obtain modified polytetrafluoroethylene.