Process and catalyst for producing syndiotactic polyolefins
US5225500A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 24, 1992 |
| Grant date | Jul 6, 1993 |
| Priority date | — |
| Expiry date | Apr 24, 2012 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S526/943
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
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 metallocene ligand having sterically dissimilar ring structures joined to a positively charged coordinating transition metal atom, and a stable noncoordinating counter anion for the metallocene cation. One of said ring structures is a substituted or unsubstituted cyclopentadienyl ring and the other of the ring structures is a substituted cyclopentadienyl group which is sterically different from the first cyclopentadienyl group. A structural bridge between cyclopentadienyl groups imparts stereorigidity to the catalyst. The catalyst is contacted with a C.sub.3 + alpha olefin or other ethylenically unsaturated compound in a polymerization reaction zone and maintained in contact with the catalyst in the reaction zone under polymerization conditions to produce a syndiotactic polymer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.