Catalyst and method of broadening polymer molecular weight distribution and increasing polymer tensile impact strength and products made thereof
AssigneeExxon Chemical Patents Inc.
InventorsMoses O. Jejelowo, Robert L. Bamberger
Life of this patent
Estimating the term…
Abstract
A catalyst and method of producing polyolefins having broadened molecular weight distributions and enhanced tensile impact strengths utilizing a silica supported metallocene-alumoxane catalyst system, wherein at least one of the metallocenes has at least one cyclopentadienyl ring being substituted by at least one optionally substituted hydrocarbon substituent having a 2.degree. or 3.degree. carbon atom with which it is covalently bonded to the cyclopentadienyl ring.
Claims18
A process for producing homo- or co- polymers having a broad molecular weight distribution comprising the steps of:
- (a) polymerizing alpha-olefin monomer, optionally with co-monomer, in the presence of a catalyst system comprising:
- (i) at least one metallocene having at least one cyclopentadienyl ring being substituted by at least one optionally substituted hydrocarbon substituent having 3 to 20 carbon atoms and having a 2.degree. or 3.degree. carbon atom and said hydrocarbon substituent is bonded to said at least one cyclopentadienyl ring at said 2.degree. or 3.degree. carbon atom;
- and
- (ii) an activator selected from ionic activators or alumoxane or combinations thereof;
- and
- (b) collecting the desired polymer.
A process for polymerizing ethylene optionally with at least one alpha-olefin comonomer in the presence of a catalyst system, said processing comprising:
- a) contacting said ethylene optionally with at least one alpha-olefin comonomer with said catalyst system, said catalyst system comprising a transition metallocene of Group IV or V of the Periodic Table of Elements having at least one substituted cyclopentadienyl ring, the substituent of which is a hydrocarbon or substituted hydrocarbon group having 3 to 20 carbon atoms and having a 2.degree. or 3.degree. carbon atom with which it is bonded to said cyclopentadienyl ring and an activator for the metallocene, and
- b) recovering a polyolefin product having a molecular weight distribution greater than about 4.
Dependencies are inferred from the claim text.