| abstract |
This invention is directed toward the polymerization of olefins, optionally with a comonomer in the presence of metallocene catalyst to produce a polymer product having a controlled molecular weight distribution, ranging from narrow to broad, a high molecular weight and a narrow composition distribution. The catalyst of the invention provides for linear polyethylenes and ethylene-α-olefin copolymers with substantially higher melt strength than linear polyethylenes produced with a conventional Ziegler-Natta catalyst or a typical metallocene catalyst. The invention provides a catalyst for polymerizing olefins comprising a first component comprising at least one transition metal of Group IV, V or VI and bonded to at least two cyclopentadienyl containing rings, said rings each having at least two substituents bonded to each of said rings in the same position; a second component comprising said transition metal and said cyclopentadienyl containing rings, said rings each having at least two substituents bonded to each of said rings in the same or different position than said substituents of said first component; said substituents of the said first and second components can be the same or different, with the provision that when the substituents of said first and second components are the same, said substituents of said components are bonded to said rings in different positions; and a third component comprising said transition metal bonded to said cyclopentadienyl containing rings where one of said rings is substituted identically as said first component and another of said rings is substituted identically as said second component. The invention further provides for catalyst systems comprising the catalyst component above in combination with a cocatalyst and/or activator for the catalyst. The cocatalyst or activator can be either alumoxane or an ionic activator. |