Process for producing stereospecific polymers

Details Process for producing stereospecific polymers Process for producing stereospecific polymers

2005-02-15

2005-02-15

Rabago, Roberto (Department: 1713)

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

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S160000, C526S346000, C526S351000, C526S943000

Reexamination Certificate

active

06855782

ABSTRACT:
Supported stereospecific catalysts and processes for the stereotactic propagation of a polymer chain derived from ethylenically unsaturated monomers which contain three or more carbon atoms or which are substituted vinyl compounds, such as styrene and vinyl chloride. One application is the stereospecific propagation of C3-C4alpha olefins, particularly the polymerization of propylene to produce syndiotactic polypropylene over a supported metallocene catalyst comprising a stereospecific metallocene catalyst component incorporating a metallocene ligand structure having two sterically dissimilar cyclopentadienyl ring structures coordinated with the central transition metal atom. Both of the cyclopentadienyl groups are in a relationship with one another by virtue of bridge or substituent groups, which provide a stereorigid relationship relative to the coordinating transition metal atom to prevent rotation of said ring structures. The metallocene catalyst component and a co-catalyst component, an alumoxane or an alkyl aluminum, are supported on a particulate silica support comprising spheroidal silica particles having an average diameter within the range of 5-40 microns and an average effective pore size within the range of 50-350 angstroms. The particulate silica support contains at least 50 wt. % of the supported catalyst component within the pore volume of the silica support.

REFERENCES:
patent: 5968864 (1999-10-01), Shamshoum et al.

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