Abstract: Provided are vinylidene fluoride copolymers exhibiting higher adhesion with respect to metal foils than do conventional vinylidene fluoride copolymers, and to provide uses of the vinylidene fluoride copolymers. The vinylidene fluoride copolymers are obtained by copolymerizing vinylidene fluoride with a compound represented by Formula (A). In Formula (A), R1, R2 and R3 are each independently a hydrogen atom, a chlorine atom or an alkyl group; and X is an atomic group with a molecular weight of not more than 500 containing a heteroatom and having a main chain composed of 1 to 20 atoms, or is a heteroatom.

Abstract: Provided is a process for producing vinylidene fluoride polymer powder that exhibits excellent solubility with respect to aprotic polar solvents, and a process for producing a vinylidene fluoride polymer solution using vinylidene fluoride polymer powder obtained by the polymer powder production process. The process for producing heat-treated vinylidene fluoride polymer powder includes heat treating raw vinylidene fluoride polymer powder at such a temperature that the temperature of the polymer powder is not less than 125° C. to less than the crystal melting temperature (Tm) of the polymer.

Abstract: Provided is a vinylidene fluoride polymer powder exhibiting excellent solubility in aprotic polar solvents, and a vinylidene fluoride polymer solution obtained from the powder and an aprotic polar solvent. The vinylidene fluoride polymer powder has an NMP penetration rate of 12 to 100% as measured by an NMP penetration test.

Abstract: A core/shell polymer (A), comprising: a rubbery core comprising a crosslinked vinylidene fluoride copolymer (a) having a vinylidene fluoride content of 30-90 wt. % and a shell comprising a vinylidene fluoride polymer (b) having a vinylidene fluoride content which is larger than in the crosslinked vinylidene fluoride copolymer (a) and at least 80 wt. %, in a weight ratio (a)/(b) of 30/70-90/10. The vinylidene fluoride-based core/shell polymer (A) is excellent in mechanical properties including flexibility and resistance to nonaqueous electrolytic solutions, is capable of forming a composite electrode layer showing excellent flexibility and adhesion to an electroconductive substrate in combination with a powder active substance and is therefore suitable for use as a binder for nonaqueous electrochemical devices.

Abstract: A positive electrode mixture for nonaqueous batteries, is formed by adding 0.5 to 10 wt. parts of an organic acid per 100 wt. parts of an electroconductive additive, to a mixture of a composite metal oxide as a positive electrode active substance, a higher order-structured carbon black as the electroconductive additive, a binder of a fluorine-containing copolymer of at least three comonomers including vinylidene fluoride, tetrafluoroethylene and a flexibility-improving fluorine-containing monomer, and an organic solvent. Further, the mixture is applied on at least one side of an electroconductive sheet, and then dried and compressed to form a positive electrode mixture layer. As a result, it is possible to provide a positive electrode structure having a thick and sound positive electrode mixture layer of a high energy density.

Abstract: A core/shell polymer (A), comprising: a rubbery core comprising a crosslinked vinylidene fluoride copolymer (a) having a vinylidene fluoride content of 30-90 wt. % and a shell comprising a vinylidene fluoride polymer (b) having a vinylidene fluoride content which is larger than in the crosslinked vinylidene fluoride copolymer (a) and at least 80 wt. %, in a weight ratio (a)/(b) of 30/70-90/10. The vinylidene fluoride-based core/shell polymer (A) is excellent in mechanical properties including flexibility and resistance to nonaqueous electrolytic solutions, is capable of forming a composite electrode layer showing excellent flexibility and adhesion to an electroconductive substrate in combination with a powder active substance and is therefore suitable for use as a binder for nonaqueous electrochemical devices.