Inventors:
Michael D. Jensen - Laurel MD, US
Michael J. Elder - Baltimore MD, US
Andrew G. Singleton - Ellicott City MD, US
Stephen R. Schmidt - Silver Spring MD, US
Patrick J. Kerwin - Grasonville MD, US
Fengjun Hua - Ellicott City MD, US
Assignee:
W.R. GRACE & CO.-CONN - Columbia MD
International Classification:
C08F 4/76
US Classification:
526114, 502129, 502113, 502104
Abstract:
Olefin polymerization catalysts or catalyst systems comprising a mixture, contact product, reaction product or complex comprising as elements or components: (A) at least one metallocene pre-catalyst compound or polymerization active metallocene compound; (B) at least one titanium containing metallocene compound; and when (A) is a metallocene pre-catalyst compound, (C) at least one activator; provided however: (I) the titanium-containing metallocene compound is inactive or substantially inactive for the polymerization of olefins prior to or concurrently with the use of the catalyst system for olefin polymerization. Also disclosed are processes for producing the catalyst system and polyolefins having desirable combinations of properties, including melt index and molecular weight distribution, which properties are particularly desirable for the manufacture of polyolefin film products, especially LLDPE film A preferred catalyst comprises a zirconium or hafnium metal containing metallocene, an inactivated titanocene and a SiO2 support carrier.
