Process for the preparation of a catalytic system, process for the (CO)polymerization of olefins and (CO)polymers of at least one olefin

A process for the (co)polymerisation of at least one olefin in the presence of a catalytic system comprising at least organoaluminiun compound of general formula AITT′T″, in which T, T′ and T″ each denote a radical which can optionally comprise oxygen, and at least one ionizing agent, and at least, one neutral halogenated metallocene selected from compounds of formula (Cp)a(Cp′)bMXx, in which:

• CP denotes an unsaturated hydrocarbon radical selected from the group consisting of cyclopentadienyl, indenyl, and fluorenyl radicals and the substtitued derivatives thereof comprising a hydrocarbon radical comprising up to 10 carbon atoms, which is coordinated to the central atom M
• Cp′ denotes an unsaturated hydrocarbon radical selected from the group consisting of cyclopentadienyl, indenyl, and fluorenyl radicals and the substituted derivatives thereof comprising a hydrocarbon radical comprising up to 10 carbon atoms, which is coordinated to the central atom M, or a radical comprising an element selected from groups VA and VIA of the Periodic Table, the groups Cp and Cp′ being identical or different, and being able to be linked via a covalent bridge
• M denotes a transition metal selected from groups IIIB, IVB, VB and VIB of the Periodic Table
• a, b, and x denote integers such that (a+b+x)=m, x>1, and a and/or by b≠0
• m denotes the valency of the transition metal M
• X denotes a halogen,
• wherein said (co)polymerization process comprises preparing a mixture of the organoaluminuin compound and of the neutral metallocene in at least one hydrocarbon diluent;
• contacting the olefin with this mixture;
• and adding the ionizing agent thereto.