Process and catalyst for producing polyolefins having low molecular weight
US6114480A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 19, 1996 |
| Grant date | Sep 5, 2000 |
| Priority date | — |
| Expiry date | Apr 19, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S526/943
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
The invention provides a metallocene catalyst for use in preparing polyolefins having low molecular weight. The catalyst comprises a metallocene compound generally described by the formula R"(C.sub.5 R.sub.4) (H.sub.2 C.sub.5 C.sub.4 H.sub.4)MeQ.sub.p wherein (C.sub.5 R.sub.4) is a substituted cyclopentadienyl ring; (H.sub.2 C.sub.5 C.sub.4 H.sub.4) is an indenyl ring; (C.sub.5 R.sub.4) 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 (C.sub.5 R.sub.4) and (H.sub.2 C.sub.5 C.sub.4 H.sub.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 m…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.