Vulcanizable fluoroelastomer compositions providing vulcanizates having high adhesion to metals

A vulcanizable fluoroelastomeric composition, comprising:

• (A) an elastomeric copolymer based on vinylidene fluoride and on at least another fluorinated monomer;
• (B) a substance endowed with the property of neutralizing acids and selected from the group consisting of the oxides of divalent metals, hydroxides of divalent metals and mixtures of said oxides and hydroxides with metal salts of weak acids;
• (C) an aromatic polyhydroxyl compound which acts as a vulcanizing agent for the copolymer,
• and characterized in that it contains, as a vulcanization accelerator, a salt consisting of a cation of phosphonium, of amino-phosphonium, or of ammonium of a type known in the art, and of a complex anion in which one atom or two atoms of a metal selected from the group consisting of Cd(II), Zn(II), Pd(II), and Ni(II) is or are bound to a halogen atom selected from the group consisting of chlorine, bromine and iodine atoms and, optionally, also to a trisubstituted phosphinic binder of the type P(C.sub.6 H.sub.5).sub.3, P[N(CH.sub.3)(C.sub.6 H.sub.5)].sub.3, said complex anion being represented by one of the following formulae:
• (MeX.sub.4).sup.2.spsp.-, (MeX.sub.3 Y).sup.-, (Me.sub.2 X.sub.6).sup.-
• wherein Me is one of the aforesaid divalent metals, X is selected from the group consisting of chlorine, bromine and iodine, Y is the aforesaid phosphinic binder, or said complex anion can be tetraphenylborate.