Fluoroelastomer composition with improved bonding properties

A method of improving the adhesion between a substrate having an inorganic surface and a cured, fluoroelastomeric composition, comprising the steps of:

• (A) providing a curable composition comprising:
• (1) fluoroelastomer gum comprising interpolymerized, repeating units derived from vinylidene fluoride, tetrafluoroethylene and copolymerizable hydrocarbon olefin,
• (2) polyhydroxy compound,
• (3) organo-onium compound,
• (4) fluoroaliphatic sulfonyl compound having at least one --SO.sub.2 NH-- or SO.sub.2 CH-- moiety wherein the sulfur atom of said --SO.sub.2 NH-- or --SO.sub.2 CH-- moiety is also bonded directly to a carbon atom substituted with at least one strongly electronegative or electron withdrawing group, and
• (5) acid acceptor,
• (B) preparing a primer composition comprising aminosilane compound,
• (C) applying the primer composition to the inorganic surface of the substrate,
• (D) placing the coated substrate from step (C) in a mold,
• (E) filling the mold with the mixture prepared in step (A),
• (F) curing the mixture, and
• (G) removing the resulting molded article from the mold, wherein the amount of fluoroaliphatic sulfonyl compound used to prepare the composition in step (A) is sufficient to result in a bond between the substrate and the cured fluoroelastomeric composition.