C - Chemistry – Metallurgy – 08 – F
Patent
C - Chemistry, Metallurgy
08
F
C08F 4/642 (2006.01) C08F 4/64 (2006.01) C08F 4/68 (2006.01) C08F 4/69 (2006.01) C08F 10/10 (2006.01) C08F 110/02 (2006.01) C08F 110/06 (2006.01)
Patent
CA 2345551
The invention provides a metallocene catalyst for use in preparing polyolefins having low molecular weight. The catalyst comprises a bridged metallocene in which one of the cyclopentadienyl rings is substituted in a substantially different manner from the other ring. The catalyst comprises a metallocene compound generally described by the formula R" (C5R4) (R'2C5C4R'4)MeQ p wherein (C5R4) is a substituted cyclopentadienyl ring; (R'2C5C4R'4n) is an indenyl ring or substituted indenyl ring; each R and R' is hydrogen or hydrocarbyl radical having from 1-20 carbon atoms, a halogen, an alkoxy, and alkoxy alkyl or an alkylamino radical, each R and R' may be the same or different; (C5R4) has one R substituent in a distal position which is at least as bulky as a t-butyl radical; R" is a structural bridge between the (C5R4) and (R'2C5C4R'4) rings to impart stereorigidity; Q is a hydrocarbyl radical, such as an alkyl, aryl, alkenyl, alkylaryl or arylalkyl radical having 1-20 carbon atoms or is a halogen; Me is a Group IIIB, IVB, VB, or VIB metal as positioned in the Periodic Table of Elements; and p is the valence of Me minus 2. This catalyst produces a crystalline or atactic polymer with a low molecular weight and narrow or broad molecular weight distribution depending upon the isomer(s) used in polymerization. A single threo-isomer produces isotactic polypropylene and a single erythro-isomer produces atactic polypropylene, both polymers having narrow molecular weight distribution. When the bridge between the substituted cyclopentadienyl and the indenyl rings is substituted such that four diastereomers are possible, the threo-isomers produce isotactic polypropylene with broad molecular weight distribution.
Lopez Margarito
Reddy B. Raghava
Shamshoum Edwar S.
Fina Technology Inc.
Gowling Lafleur Henderson Llp
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