Process and catalyst for producing syndiotactic polymers
US5278265A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 25, 1993 |
| Grant date | Jan 11, 1994 |
| Priority date | — |
| Expiry date | May 25, 2013 |
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. The ring structures are substituted cyclopentadienyl rings which are sterically different from one another at sufficiently low kinetic energy states induced by the substituents on the cyclopentadienyl groups to impart a stereorigid relationship relative to said coordinating metal atom to prevent rotation of the rings about their coordination axes at the polymerization temperature. The catalyst with a C3+ alpha olefin or ther ethylenically unsaturated compound in a polymerization reaction zone and maintained in contact with the catalyst in the reaction zone under low termperature polymerization conditions to produce a syndiotactic polymer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.