Cyclobutyl silanes for catalysts useful for making highly isotactic olefin polymers

Abstract

One aspect of the present invention relates to a catalyst system for use in olefinic polymerization, containing a solid titanium catalyst component prepared by contacting a titanium compound and a magnesium compound; an organoaluminum compound having at least one aluminum-carbon bond; and an organosilicon compound comprising at least one of cyclobutyl group. Another aspect of the present invention relates to a method of making a catalyst for use in olefinic polymerization, involving the steps of reacting a Grignard reagent having a cyclobutyl group with an orthosilicate to provide an organosilicon compound having a cyclobutyl moiety; and combining the organosilicon compound with an organoaluminum compound having at least one aluminum-carbon bond and a solid titanium catalyst component prepared by contacting a titanium compound and a magnesium compound.

Description

FIELD OF THE INVENTIONThe present invention generally relates to olefin polymerization catalyst systems. In particular, the present invention relates to catalyst systems for making olefin polymers and copolymers and methods of making the catalyst systems and alpha-olefin polymers and copolymers that are highly isotactic.BACKGROUND OF THE INVENTIONPolyolefins are a class of polymers derived from simple olefins and include polypropylene and polybutene. Known methods of making polyolefins involve the use of Ziegler-Natta polymerization catalysts. These catalysts polymerize vinyl monomers using a transition metal halide to provide a stereoregulated polymer.Numerous Ziegler-Natta polymerization catalysts exist. The catalysts have different characteristics and / or lead to the production of polyolefins having diverse properties. For example, certain catalysts have high activity while other catalysts have low activity, and similarly certain catalysts have a long life while other catalysts ha...

AI Technical Summary

Benefits of technology

The present invention provides alpha-olefin polymerization catalyst systems, methods of making the alpha-oleafin polymerization catalyst systems, and methods of polymerizing (and copolymerizing) alpha-olefins involving the use of cyclobutyl moiety containing external electron donors. The cyclobutyl moiety containing external electron donors of the alpha-olefin polymerization catalyst systems contribute to the production of low xylene soluble poly-alpha-olefins while simultaneously maintaining high catalytic efficiency of the catalysts. The production of highly isotactic poly-alpha-olefins is enabled by the cyclobutyl moiety containing external electron donors of the alpha-olefin polymerization catalyst systems. The use of cyclobutyl moiety containing external electron donors permits the tolerance of a large margin of error in the amount of external electron donor employed without effecting the properties of the catalyst system or resulting polymer.

Problems solved by technology

However, using an electron donor to promote increased stereospecificity of poly-alpha-olefins in a Ziegler-Natta polymerization scheme tends to cause large losses in catalyst activity.

While lower levels of many characteristics associated with Ziegler-Natta polymerization catalysts can be tolerated, it is difficult to accommodate compromises in catalyst activity.