Repsol Quimica, S.a.

Respsol Quimica S.a.

Antonio Munoz-Escalona

Jose Sancho Royo

Gerardo Hidalgo Llinas

Wilfried Michiels Vega

Begona Pena Garcia

The process is characterized by the use of catalyst systems consisting of a single metallocene catalyst activated with mixtures of at least 2 co-catalysts. The co-catalysts are aluminium alkyls, aluminoxanes or boron compounds. Different active centers are produced in the catalyst through the use of these mixed co-catalyst systems, each having different rates of initiation and completion of the polymerization reaction, which give rise to polyolefins with different molecular weights, resulting in products with broad bimodal or multimodal molecular weight distributions and the incorporation of co-monomer can be controlled by appropriate selection of the metallocene and use of combinations of different types of co-catalysts, as well as by varying the reactor pressure, the reaction temperature and the molar ratios between the various components of the catalyst system. A broad bimodal or multimodal molecular weight distribution can be achieved in both the presence and absence of hydrogen during the polymerization reaction. Likewise broad bimodal and multimodal molecular weight distributions can be obtained in polymers by varying the order in which the components of the catalyst system are added. This process may also be used with both homogeneous and heterogenous metallocene catalysts.

Process for obtaining polyolefins with broad bimodal or multimodal molecular weight distributions

Catalytic systems particularly suitable for the polymerization of .alpha.-olefins containing from two to 20 carbon atoms, as well as for the copolymerization of ethylene with .alpha.-olefins containing from three to 20 carbon atoms, dienes, and cycloalkenes in processes wherein the catalyst is suspended in a solvent, in processes in gas phase, as well as in mass polymerization processes at high temperatures and pressures, are disclosed. The catalytic system is a mixture of a catalyst component A and a co-catalyst component B. The catalyst component A is formed by a functionalized inorganic porous oxide, by an organoaluminium compound and by an organometallic compound of a metal of the groups 3, 4, 5, or 6 of the periodic table. Functionalization of the inorganic oxide is by introduction of functional groups to be used to strongly fix the organoaluminium compound and the organometallic compound. The co-catalyst component B, which is used for the activation of the catalyst, is formed of organoaluminium compounds, perfluorinated derivatives of boron, or a mixture thereof.

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Madrid, Spain

Antonio Munoz-Escalona