Process and catalyst for producing syndiotactic polymers

Details Process and catalyst for producing syndiotactic polymers Process and catalyst for producing syndiotactic polymers

1992-04-24

1993-09-07

Garvin, Patrick P.

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

Synthetic resins

Polymers from only ethylenic monomers or processes of...

526160, 526351, 502103, 502117, 502152, C08F 464

Patent

active

052430022

ABSTRACT:
Syndiospecific catalysts and process for the syndiotactic propagation of a polymer chain derived from an ethylenically unsaturated monomer which contains 3 or more carbon atoms or is substituted vinyl compound. The catalysts comprise unbalanced stereorigid metallocenes in which a structural bridge is not required for stereorigidity. The ring structures of the metallocene catalyst are substituted cyclopentadienyl rings, which are sterically different from one another. The substituent groups on the cyclopentadienyl rings impart stereorigidity to the catalyst by virtue of a sterically hindered relationship between the rings sufficient to prevent rotation of the rings, or by virtue of the cyclopentadienyl groups being at a low kinetic energy state induced by the substituents to prevent rotation of the rings about their coordination axes at the temperature of the catalyst. The catalyst is contacted with a C3+ 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.

REFERENCES:
patent: 4794096 (1988-12-01), Ewen
patent: 4892851 (1990-01-01), Ewen et al.
Zambelli et al., Macromolecules, 1989, pp. 2186-2189.
Jordan et al., JACS (1986), 108, pp. 7410-7411, 1718-1719.

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