Patent ID: 6133385
Filing Date: 2000-10-17
Classification: C08F,Y02P

Abstract:
A process for the polymerization of propylene, comprising:(a) selecting a conventional Ziegler-Natta catalyst which comprises a transition metal compound of the general formula MR.sup.+.sub.x where M is titanium, R.sup.+ is a halogen or a hydrocarboxyl and x is the valence of titanium;(b) contacting the catalyst with an organoaluminum compound;(c) contacting the catalyst with a mixture of at least two electron donors, simultaneously with or after step (b), the first described by the formula: ##STR9## wherein R.sub.1 and R.sub.4 are both an alkyl or cycloalkyl group containing a secondary or tertiary carbon atom attached to the silicon atom, R.sub.1 and R.sub.4 being the same, R.sub.2 and R.sub.3 are alkyl or aryl groups, R.sub.2 and R.sub.3 being the same or different,and the second is cyclohexylmethyldimethoxysilane,wherein the two electron donors are in a molar ratio of from about 1:3 to about 1:1 of the second to the first, andwherein silicon and titanium are in a molar ratio (Si/Ti molar ratio) within the range from about 0.5 to about 10;(d) introducing the catalyst into a polymerization reaction zone containing said organoaluminum compound, said electron donors and monomer; and(e) extracting polypropylene from the polymerization reaction zonewherein the polypropylene has a polydispersity from about 9.5 to about 10.