Process for producing syndiotactic polyolefins
US5334677A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 15, 1991 |
| Grant date | Aug 2, 1994 |
| Priority date | — |
| Expiry date | Nov 15, 2011 |
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 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 highly syndiospecific, and it also produces a polymer with a novel microstructure. The invention further includes the use of one or more of the catalysts in a polymerization process. The catalyst is generally described by the formula EQU R"(CpR.sub.n)(CpR'.sub.m)MeQ.sub.k wherein each Cp is a cyclopentadienyl or substituted cyclopentadienyl ring; each R.sub.n and R'.sub.m is the same or different and is a hydrocarbyl radicals having 1-20 carbon atoms; R" is a structural bridge between the two Cp rings imparting stereorigidity to the catalyst; Me is a group 4b, 5b, or 6b metal from the Periodic Table of Elements; each Q is a hydrocarbyl radical having 1-20 carbon atoms or is a halogen; 0.ltoreq.k.ltoreq.3; 0.ltoreq.n.ltoreq.4; 1.ltoreq.m.ltoreq.4; and wherein R'.sub.m is selected such that (CpR'.sub.m) is a sterically different ring than (CpR.sub.n).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.