To provide a fluorinated copolymer composition whereby a crosslinked rubber article which has a low compression set at high temperature and which is not broken after compression can be formed, and a crosslinked rubber article.

The fluorinated copolymer composition of the present invention comprises a fluorinated copolymer having nitrile groups, a phosphorus compound having a melting point of 60° C. or lower and a crosslinking agent.

To provide a fluorinated copolymer composition whereby a crosslinked rubber article which has a low compression set at high temperature and which is not broken after compression can be formed, and a crosslinked rubber article.

The fluorinated copolymer composition of the present invention comprises a fluorinated copolymer (A) having units having a nitrile group and units based on tetrafluoroethylene, a fluorinated copolymer (B) having units having at least one functional group selected from the group consisting of a group having a carbonyl group, a hydroxy group, an epoxy group and an isocyanate group and units based on tetrafluoroethylene, and a crosslinking agent.

To provide a fluorinated copolymer composition whereby a crosslinked rubber article which has a low compression set at high temperature and which is not broken after compression can be formed, and a crosslinked rubber article.

The fluorinated copolymer composition of the present invention comprises a fluorinated copolymer (A) having units having a nitrile group and units based on tetrafluoroethylene, a fluorinated copolymer (B) having units having at least one functional group selected from the group consisting of a group having a carbonyl group, a hydroxy group, an epoxy group and an isocyanate group and units based on tetrafluoroethylene, and a crosslinking agent.

Provided is a copolymer consisting essentially of ethylene units, tetrafluoroethylene units, and hexafluoropropylene units, wherein a molar ratio (Et units/TFE units) of the ethylene (Et) units to the tetrafluoroethylene (TFE) units is 52.0/48.0 to 56.0/44.0, and a content of the hexafluoropropylene units is 19.0 to 21.0 mol % based on the total monomer units constituting the copolymer.

A coating material of the present invention is a coating material containing: a fluorine-containing polymer having at least one of an iodine atom and a bromine atom; and a solvent, wherein a storage elastic modulus G′ of the fluorine-containing polymer is less than 360 kPa, and a total light transmittance of a mixed liquid obtained by mixing and stirring the fluorine-containing polymer and the solvent contained in the coating material is 1.0% or more, the mixed liquid being left to stand for 3 days, stirred again, and left to stand for 30 minutes to measure the total light transmittance.

A coating material of the present invention is a coating material containing: a fluorine-containing polymer having at least one of an iodine atom and a bromine atom; and a solvent, wherein a storage elastic modulus G′ of the fluorine-containing polymer is less than 360 kPa, and a total light transmittance of a mixed liquid obtained by mixing and stirring the fluorine-containing polymer and the solvent contained in the coating material is 1.0% or more, the mixed liquid being left to stand for 3 days, stirred again, and left to stand for 30 minutes to measure the total light transmittance.

An object is to provide a fluorine-containing copolymer composition that exhibits long-term stability as well as a fluororesin paint or varnish prepared using the composition.

Provided are: a composition comprising a fluorine-containing copolymer synthesized through copolymerization of 0.001 to 50 mol % of particular ethylenically unsaturated organosilicon compound polymerization units relative to 5 to 85 mol % of fluoroolefin polymerization units by a solution polymerization method, a solvent, and an amine compound; a fluororesin paint or varnish prepared using the composition; and a method of producing the fluorine-containing copolymer composition.

A method of producing a heat-resistant crosslinked fluororubber formed body, including a step (1) of melt-mixing, with respect to 100 mass parts of base rubber containing 40 to 98 mass % of fluororubber and 2 to 40 mass % of ethylene/tetrafluoroethylene copolymer resin, 0.003 to 0.5 mass parts of organic peroxide, 0.5 to 400 mass parts of inorganic filler, 2 to 15 mass parts of a specific silane coupling agent, and silanol condensation catalyst, and including a step (a) of melt-mixing a part of the base rubber, the organic peroxide, the inorganic filler and the silane coupling agent at a temperature equal to or higher than a decomposition temperature of said organic peroxide, and a step (b) of melt-mixing a remainder of the base rubber, and the silanol condensation catalyst, and the fluororubber and the ethylene/tetrafluoroethylene copolymer resin are melt-mixed in any of the steps (a) and (b).

A fluororesin having a tensile strength retention ratio of 50% or more, the tensile strength retention ratio being calculated by the following formula from the tensile strength of the fluororesin after a heat treatment obtained by conducting a heat treatment at 130° C. for 40,000 hours, and the tensile strength of the fluororesin before the heat treatment. Tensile strength retention ratio (%)=(tensile strength of fluororesin after heat treatment (MPa))/(tensile strength of fluororesin before heat treatment (MPa))×100.

A fluororesin having a tensile strength retention ratio of 50% or more, the tensile strength retention ratio being calculated by the following formula from the tensile strength of the fluororesin after a heat treatment obtained by conducting a heat treatment at 130° C. for 40,000 hours, and the tensile strength of the fluororesin before the heat treatment. Tensile strength retention ratio (%)=(tensile strength of fluororesin after heat treatment (MPa))/(tensile strength of fluororesin before heat treatment (MPa))×100.