| abstract |
A catalyst system comprising the product obtained by contacting (a) a solid catalyst component containing Mg, Ti, halogen and at least an electron donor compound selected from diolesters of a specific formula (b) an alkylaluminum cocatalyst and (c) an ester of formula R'OOC-(CR" 2 ) m -COOR' in which m is an integer from 2 to 8, the R' groups, equal to or different from each other, are C1-C10 alkyl groups and the R" groups, independently, are hydrogen or C1 -C15 hydrocarbon groups. |