Supported metallocene catalysts

Abstract

Supported metallocene catalysts and the use of such catalysts in the isotactic polymerization of C3+ ethylenically unsaturated monomers. The supported catalyst comprises a particulate silica support, an alkylaluminoxane component and a metallocene catalyst component. The average particle size of the carrier is 10-50 microns, the surface area is 200-800 square meters per gram, and the pore volume is 0.9-2.1 milliliters per gram (ml / g). The aluminoxane is incorporated into the carrier in a weight ratio of aluminoxane to silica of at least 0.8:1. The content of metallocene is at least 1% by weight of silica and aluminoxane, and the chemical formula of metallocene is B(CpRaRb)(Fl')MQ2, wherein Fl' is unsubstituted fluorenyl or in the 3 and 6 positions Symmetrically substituted fluorenyl, B is the structural bridge between Cp and Fl', Ra is the bulky substituent at the distal position, Rb is the less bulky substituent at the distal position, Rb is the adjacent bridge Smaller volume substituents, and non-joint to the far-side substituents, M is a transition metal of Group IVB or vanadium, Q is halogen or C1-C4 alkyl.

Description

field of invention [0001] This invention relates to catalysts and processes for the preparation of isotactic alpha-olefins, and more particularly to supported bridged cyclopentadienyl-fluorenylcenes on alumoxane-treated silica supports Metals and their applications. Background of the invention [0002] Syndiotacticity and isotacticity relate to two broad classes of stereoregular structure formation that can be involved in the formation of stereoregular polymers from various monomer units. Syndiotactic polymers, such as syndiotactic polypropylene, have a stereochemical structure in which the monomer units have an enantiomeric configuration in which methyl groups on asymmetric carbon atoms Alternately and regularly distributed along the polymer backbone. Unlike the alternating configuration of syndiotactic polymers, isotactic polymers such as isotactic polypropylene are generally characterized by the same sequential configuration of the methyl groups on the repeating units. ...

AI Technical Summary

Problems solved by technology

Although these compounds are similar to the syndiotactic metallocenes disclosed by Razavi et al. in U.S. Patent No. 5,334,677, they are not characterized by left-right symmetry due to the advantage of having substituents on the far side of the cyclopentadienyl ring

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