| abstract |
A solid catalyst component for the (co)polymerization of olefins CH2=CHR, in which R is a hydrocarbyl radical with 1-12 carbon atoms, optionally in mixture with ethylene, comprising Ti, Mg, Zn, Cl, and an electron donor compound characterized by the fact that more than 50% of the titanium atoms are in the +4 valence state, and that the amount of Zn ranges from 0.1 to 5% by weight based on then total weight of said solid catalyst component. The solid catalyst component shows and increased activity/stereospecificity balance. |