Process and catalyst for producing syndiotactic polyolefins

Details Process and catalyst for producing syndiotactic polyolefins Process and catalyst for producing syndiotactic polyolefins

1992-04-24

1993-07-06

Garvin, Patrick P.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

526126, 526131, 526132, 526134, 526150, 526160, 526170, 526351, 502103, 502117, C08F 464

Patent

active

052255000

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.

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Zambelli et al, Macromolecules 1989, 22, pp. 2186-2189.
Jordan et al, JACS, 1986, 108, pp. 1718-1719.
Jordan et al, JACS, 1986, 108, pp. 7410-7411.

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