Catalyst for bimodal molecular weight distribution ethylene polymers and copolymers
AssigneeMobil Oil Corporation
InventorsRobert I. Mink, Thomas E. Nowlin, Sandra D. Schregenberger, Pradeep P. Shirodkar, Grace O. Tsien
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Abstract
The interaction of silica, previously calcined at 600.degree. C., with dibutylmagnesium (DBM), 1-butanol and titanium tetrachloride and a solution of methylalumoxane (MAO) and (BuCp).sub.2 ZrCl.sub.2 provides a catalyst that, in the absence of a trialkylaluminum (AlR.sub.3) cocatalyst, produces polyethylene with a bimodal MWD.
Claims16
An activated catalyst composition, for producing bimodal molecular weight distribution high density and linear low density polymers and copolymers of ethylene, which activated catalyst does not require a cofeed selected from the group consisting of aluminoxane, trialkyaluminum and mixtures thereof, to the reactor comprising
- a dry, anhydrous, support containing composition comprising at least two transition metals one of which is provided as a metallocene compound and a second of which is provided as a transition metal source selected from the group consisting of non-metallocene compounds, activated by
- a solution containing at least one source of aluminum and selected from the group consisting of aluminoxane alone and aluminoxane admixed with metallocene transition-metal compound wherein at least one source of aluminum is present in amounts effective to activate the two transition metals;
- wherein the metallocene transition metal is provided as a compound which has the formula Cp.sub.x MA.sub.y B.sub.z, wherein Cp is selected from the group consisting of (1) an unsubstituted cyclopentadienyl group;
- (2) a substituted cyclopentadienyl group, substituted by an alkyl or alkylene group of 1 to 6 carbon atoms;
- and (3) a cyclopentadienyl group which is part of a bicyclic or a tricyclic moiety, unsubstituted or substituted by an alkyl or alkylene group of 1 to 6 carbon atoms;
- x is at least 1;
- each of A and B is a halogen atom or an alkyl group of 1 to 8 carbon atoms, and y plus z is 3 or less provided that x+y+z is equal to the valence of M, which is selected from the group consisting of titanium or zirconium or hafnium;
- substituted by an alkyl or alkylene group of 1 to 6 carbon atoms;
- x is at least 1;
- each of A and B is a halogen atom or an alkyl group of 1 to 8 carbon atoms, and y plus z is 3 or less provided that x+y+z is equal to the valance of M, which is selected from the group consisting of titanium or zirconium or hafnium.
Dependencies are inferred from the claim text.