1
Howard C Welborn Jr, John A Ewen: Process and catalyst for polyolefin density and molecular weight control. Exxon Chemical Patents, Myron B Kurtzman, Charles M Cox, Ben C Cadenhead, June 28, 1994: US05324800 (420 worldwide citation)

Catalysts comprising (a) derivatives of mono, bi and tricyclopentadienyl coordination complexes with a transition metal and (b) and an alumoxane are employed in a process of producing polyolefins of controlled molecular weight.


2
John A Ewen, Howard C Welborn Jr: Process and catalyst for producing reactor blend polyolefins. Exxon Research & Engineering Company, M B Kurtzman, June 26, 1990: US04937299 (321 worldwide citation)

Polyolefin reactor blends obtained by polymerization of ethylene and higher alpha-olefins in the presence of a catalyst system comprising two or more metallocenes and alumoxane.


3
John A Ewen: Hafnium metallocene catalyst for the polymerization of olefins. Fina Technology, John K Abokhair, Stuart L Watt, M Norwood Cheairs, December 27, 1988: US04794096 (318 worldwide citation)

The present invention provides a catalyst system for the polymerization and copolymerization of olefins with the system comprising a chiral, stereorigid hafnium metallocene catalyst in combination with an aluminum compound. The aluminum compound is preferably an alumoxane and may be a mixture of alu ...


4
John A Ewen, Abbas Razavi: Process and catalyst for producing syndiotactic polyolefins. Fina Technology, Stuart L Watt, John K Abokhair, M Norwood Cheairs, January 9, 1990: US04892851 (286 worldwide citation)

The invention provides a metallocene catalyst for use in preparing syndiotactic polyolefins. The catalyst comprises a bridged metallocene in which one of the cyclopentadienyl rings is substituted in a substantially different manner from the other ring. It was discovered that this type of catalyst is ...


5
John A Ewen, Howard C Welborn Jr: Process and catalyst for producing polyethylene having a broad molecular weight distribution. Exxon Research & Engineering Co, M B Kurtzman, July 23, 1985: US04530914 (276 worldwide citation)

Polyolefins having a broad molecular weight distribution are obtained by polymerizing ethylene or higher alpha-olefins in the presence of a catalyst system comprising two or more metallocenes each having different propagation and termination rate constants and alumoxane.


6
John A Ewen, Michael J Elder: Preparation of metallocene catalysts for polymerization of olefins. Fina Technology, Jim D Wheelington, M Norwood Cheairs, February 7, 1995: US05387568 (141 worldwide citation)

This invention uses a new method of producing ionic metallocene compounds. These compounds are useful as catalysts for polymerization of olefins, primarily propylene. This method uses an ionizing agent which ionizes the neutral metallocene compound. The ionizing ionic compound does not contain an ac ...


7
Michael J Elder, Abbas Razavi, John A Ewen: Process and catalyst for producing syndiotactic polyolefins. Fina Technology, William D Jackson, Jim D Wheelington, October 13, 1992: US05155080 (134 worldwide citation)

Syndiospecific catalysts and processes for the syndiotactic propagation of a polymer chain derived from an ethylenically unsaturated monomer which contains 3 or more carbon atoms or is a substituted vinyl compound. The catalysts comprise an unbalanced metallocene cation, characterized by a cationic ...


8
John A Ewen, Howard C Welborn Jr: Process and catalyst for producing polyethylene having a broad molecular weight distribution. Exxon Research & Engineering Company, M B Kurtzman, June 19, 1990: US04935474 (117 worldwide citation)

Polyolefins having a broad molecular weight distribution are obtained by polymerizing ethylene or higher alpha-olefins in the presence of a catalyst system comprising two or more metallocenes each having different propagation and termination rate constants and alumoxane.


9
John A Ewen: Catalyst for producing hemiisotactic polypropylene. Fina Technology, Jim D Wheelington, July 30, 1991: US05036034 (105 worldwide citation)

This invention is for a metallocene compound which can be used in a catalyst system to produce hemiisotactic polymer. The compound is a bridged metallocene compound having dissimilar cyclopentadienyl groups and no bi-lateral symmetry. One example of the compound is isopropylidene(3-methylcyclopentad ...


10
John A Ewen: Catalyst systems for producing polyolefins having a broad molecular weight distribution. Fina Technology, Jim D Wheelington, John K Abokhair, M Norwood Cheairs, December 4, 1990: US04975403 (90 worldwide citation)

The invention provides catalyst systems for use in the polymerization of olefins to produce a polymer product having a broad molecular weight distribution. The catalyst system includes at least two different chiral, stereo-rigid metallocene catalysts of the formula R"(C.sub.5 (R').sub.4).sub.2 MeQp ...