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 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.

A composition containing a fluorine-containing polymer and a silicon oxide represented by formula: SiO.sub.x, where 0<x<2. In a preferred embodiment, the composition contains a cross-linking agent. Also disclosed is a crosslinked product which may be a sealing material obtained by crosslinking the composition.

A composition containing a fluorine-containing polymer and a silicon oxide represented by formula: SiO.sub.x, where 0<x<2. In a preferred embodiment, the composition contains a cross-linking agent. Also disclosed is a crosslinked product which may be a sealing material obtained by crosslinking the composition.

To provide a fluorinated copolymer, whereby it is possible to produce a crosslinked rubber article excellent in mold release properties.

The fluorinated copolymer of the present invention has units based on tetrafluoroethylene, units based on a perfluoro(alkyl vinyl ether), units based on a monomer having a fluorine atom and at least two polymerizable unsaturated bonds, and units based on a monomer having a nitrile group and a fluorine atom.

To provide a fluorinated copolymer, whereby it is possible to produce a crosslinked rubber article excellent in mold release properties.

The fluorinated copolymer of the present invention has units based on tetrafluoroethylene, units based on a perfluoro(alkyl vinyl ether), units based on a monomer having a fluorine atom and at least two polymerizable unsaturated bonds, and units based on a monomer having a nitrile group and a fluorine atom.

The invention pertains to a fluoroelastomer having a branched structure including long chain branches and including cure-site monomers, and curable composition thereof, able to provide for cured parts having ability to retain outstanding sealing performances at very high temperatures, up to about 350° C., to a method of curing the same and to cured articles obtained therefrom, which are notably useful as sealing parts in semi-conductors industry.

A method for producing a perfluoroelastomer, which includes carrying out polymerization of a perfluoromonomer in an aqueous medium in the presence of a polymer (1) having a number average molecular weight of 0.3×10.sup.4 or more to provide a perfluoroelastomer, the polymer (1) containing a polymerized unit (1) derived from a monomer represented by the following general formula (1):

CX.sub.2═CY(—CZ.sub.2—O—Rf-A)   (1)

wherein X, Y, Z, Rf and A are as defined herein, with the proviso that at least one of X, Y, and Z contains a fluorine atom.