Crosslinkable fluorine rubber composition, fluorine rubber molded article, and method for producing same

1. A crosslinkable fluororubber composition comprising:

a fluororubber (A); and

a fluororesin (B),

wherein the fluororesin (B) is a copolymer (B1) consisting of tetrafluoroethylene units (a) and hexafluoropropylene units (b) or a copolymer (B2) comprising tetrafluoroethylene units (a), hexafluoropropylene units (b), and polymerized units (c) derived from a monomer copolymerizable with tetrafluoroethylene and hexafluoropropylene,

the copolymer (B1) satisfies the condition that the ratio (a)/(b) is (80.0 to 87.3)/(12.7 to 20.0) on a molar basis, and

the copolymer (B2) satisfies the condition that the ratio (a)/(b) is (80.0 to 90.0)/(10.0 to 20.0) on a molar basis, and the ratio (c)/{(a)+(b)} is (0.1 to 10.0)/(90.0 to 99.9) on a molar basis,

wherein the fluororesin (B) has a storage elastic modulus (E′), as determined by a viscoelasticity analysis at 70° C., of 10 to 160 MPa.

2. The crosslinkable fluororubber composition according to claim 1 ,

wherein the crosslinkable fluororubber composition comprises co-coagulated powder comprising a co-coagulation of the fluororubber (A) and the fluororesin (B), and

the fluororesin (B) is the copolymer (B1).

3. The crosslinkable fluororubber composition according to claim 1 ,

wherein the crosslinkable fluororubber composition comprises co-coagulated powder comprising a co-coagulation of the fluororubber (A) and the fluororesin (B), and

the fluororesin (B) is the copolymer (B2).

4. The crosslinkable fluororubber composition according to claim 1 ,

wherein the polymerized units (c) of the fluororesin (B) are units derived from a perfluoro(alkyl vinyl ether).

5. The crosslinkable fluororubber composition according to claim 1 ,

wherein the fluororesin (B) has a melting point of not higher than 210° C.

6. The crosslinkable fluororubber composition according to claim 1 ,

wherein the fluororubber (A) is at least one selected from the group consisting of vinylidene fluoride/hexafluoropropylene copolymers, vinylidene fluoride/hexafluoropropylene/tetrafluoroethylene copolymers, tetrafluoroethylene/propylene copolymers, tetrafluoroethylene/propylene/vinylidene fluoride copolymers, ethylene/hexafluoropropylene copolymers, ethylene/hexafluoropropylene/vinylidene fluoride copolymers, ethylene/hexafluoropropylene/tetrafluoroethylene copolymers, vinylidene fluoride/tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymers, and vinylidene fluoride/chlorotrifluoroethylene copolymers.

7. The crosslinkable fluororubber composition according to claim 1 ,

wherein the fluororubber (A) comprises copolymerized units derived from a crosslinking-site-imparting monomer.

8. A fluororubber molded article comprising a crosslinked crosslinkable fluororubber composition according to claim 1 .

9. A method for producing a fluororubber molded article, comprising the steps of:

(I) co-coagulating a fluororubber (A) and a fluororesin (B), thereby providing co-coagulated powder, and then preparing a crosslinkable fluororubber composition according to claim 1 ;

(II) molding and crosslinking the crosslinkable fluororubber composition, thereby providing a crosslinked molded article; and

(III) heating the crosslinked molded article to a temperature of not lower than the melting point of the fluororesin (B), thereby providing a fluororubber molded article.

10. A fluororubber molded article obtained by the production method according to claim 9 .

11. The fluororubber molded article according to claim 8 ,

wherein the fluororubber molded article is a sealing material.

12. The fluororubber molded article according to claim 8 ,

wherein the fluororubber molded article is a sliding member.

13. The fluororubber molded article according to claim 8 ,

wherein the fluororubber molded article is a non-stick member.

14. The fluororubber molded article according to claim 8 ,

wherein the fluororubber molded article has a water/oil repellent surface.