Electron donors for improved olefin polymerization.

摘要

The present invention provides a catalyst system that exhibits unprecedented catalyst efficiencies and control of desired properties in the polymer product. The catalyst system includes a new generation titanium catalyst in combination with an electron donor described by the formula: <CHEM> wherein R1 is an alkyl group containing a tertiary carbon atom attached to the silicon atom; R2 and R3 are alkyl or aryl groups; and R4 is an alkyl group with a tertiary carbon atom attached to the silicon atom; R1 and R4 are the same or different R1 and R4 are preferably tertiary carbon groups of 4-13 carbon atoms, more preferably 4-7 carbon atoms; most preferably R1 and R4 are the same and are t-butyl groups. The system has a catalyst efficiency of over 25 kg/g-cat.h as the Si/Ti mote ratio varies from 4-200 in the system. The system easily achieves efficiencies over 25 kg/g-cat.h. The system also exhibits good control over the xylene solubles of the polymer products.