Polyhydroxy curable fluoroelastomer composition

1. A curable fluoroelastomer composition comprising:

A) a polyhydroxy curable fluoroelastomer;

B) a polyhydroxy curative; and

C) a mixture of anion trappers comprising γ-aluminum oxide hydroxide and magnesium oxide.

2. The curable fluoroelastomer composition of claim 1 wherein said polyhydroxy curable fluoroelastomer is selected from the group consisting of copolymers of i) vinylidene fluoride with hexafluoropropylene and, optionally, tetrafluoroethylene; ii) vinylidene fluoride with a perfluoro(alkyl vinyl ether), 2-hydropentafluoropropylene and optionally, tetrafluoroethylene; iii) tetrafluoroethylene with propylene and 3,3,3-trifluoropropene; iv) tetrafluoroethylene, perfluoro(methyl vinyl ether) and hexafluoro-2-(pentafluorophenoxy)-1-(trifluorovinyloxy) propane, and v) ethylene with tetrafluoroethylene, perfluoro(methyl vinyl ether) and 3,3,3-trifluoropropylene.

3. The curable fluoroelastomer composition of claim 1 wherein said mixture of anion trappers is present in an amount between 1 and 25 parts by weight per hundred parts by weight fluoroelastomer.

4. The curable fluoroelastomer composition of claim 3 wherein said mixture of anion trappers comprises 0.75 to 20 parts by weight γ-aluminum oxide hydroxide, per hundred parts by weight fluoroelastomer.

5. A polyhydroxy cured fluoroelastomer article comprising:

A) a fluoroelastomer; and

B) a mixture of anion trappers comprising y-aluminum oxide hydroxide and magnesium oxide.

6. The polyhydroxy cured fluoroelastomer article of claim 5 wherein said mixture of anion trappers is present in an amount between 1 and 25 parts by weight per hundred parts by weight fluoroelastomer.

7. The polyhydroxy cured fluoroelastomer article of claim 6 wherein said mixture of anion trappers comprises 0.75 to 20 parts by weight γ-aluminum oxide hydroxide, per hundred parts by weight fluoroelastomer.

8. The polyhydroxy cured fluoroelastomer article of claim 5 wherein said fluoroelastomer is selected from the group consisting of copolymers of i) vinylidene fluoride with hexafluoropropylene and, optionally, tetrafluoroethylene; ii) vinylidene fluoride with a perfluoro(alkyl vinyl ether), 2-hydropentafluoropropylene and optionally, tetrafluoroethylene; iii) tetrafluoroethylene with propylene and 3,3,3-trifluoropropene; iv) tetrafluoroethylene, perfluoro(methyl vinyl ether) and hexafluoro-2-(pentafluorophenoxy)-1-(trifluorovinyloxy) propane, and v) ethylene with tetrafluoroethylene, perfluoro(methyl vinyl ether) and 3,3,3-trifluoropropylene.

9. The polyhydroxy cured fluoroelastomer article of claim 5 wherein said article has a volume swell less than 10 vol % after exposure to an acid condensate of sulfuric acid/nitric acid/acetic acid/formic acid in the ratio of 2500ppm/50ppm/10ppm/1000ppm/300ppm at 60° C. for 336 hours.