Patent ID: 7019090

Claim:
A catalyst obtained by the process for the manufacture of a prepolymerized catalytic composition for the polymerization of olefins comprising: a—the manufacture of a first prepolymer by prepolymerizing at least one first olefin in the presence of a solid catalyst A, then b—the impregnation of the said first prepolymer with a solution of a catalyst B, then c—the prepolymerization of at least one second olefin in the presence of the impregnated first prepolymer to form the catalyst; wherein the solid catalyst A contains magnesium, chlorine and titanium atoms, and the prepolymerization in the presence of catalyst A is carried out in the presence of a cocatalyst; wherein the catalyst B is selected from compounds of formula ML x in which M represents a transition metal, x represents a number equal to the valency of the transition metal and L represents a ligand coordinated to the transition metal, at least one ligand L being a group with cycloalkadienyl skeleton; the catalyst A and the catalyst B containing a transition metal and the catalyst A and the catalyst B being different and not being such that at the same time: the catalyst A comprises a group with a cycloalkadienyl skeleton, and the catalyst B comprises a group with a cycloalkadienyl skeleton.