CATALYST AND PROCESS FOR THE POLYMERIZATION AND COPOLYMERIZATION OF ALPHA-OLEFINS

Alpha-olefin polymers and copolymers are prepared by polymerizing the monomers in the presence of a catalyst obtained by bringing into contact: a) a compound definable by the formula: where: M represents a metal of group 4B of the periodic table of elements; each R independently represents a halogen atom; a linear or branched C1-C10 alkyl group; or an aryl group; and each Cp independently represents the cyclopentadienyl, indenyl or fluorenyl group, possibly carrying one or more C1-C4 alkyl substituents, which Cp groups can also be connected together by a carbon atom or alkylsilane bridge structure; b) a trialkylaluminium: where each R min independently represents a linear or branched C1-C10 alkyl group, or an aryl group; and c) a distannoxane: where each R sec independently represents a linear or branched C1-C6 alkyl group, or an aryl group; the molar ratio of component (b) to component (a) being less than about 700,000/1 and the molar ratio of component (c) to component (b) being less than 1/1. The catalyst is active in the homopolymerization of ethylene, propylene and higher alpha-olefins, in the copolymerization of ethylene with propylene or with a higher alpha-olefin, and in the terpolymerization of ethylene, propylene and diene.