Patent ID: 7019097

Claim:
A process comprising polymerizing ethylene, optionally in mixtures with olefins CH 2 ═CHR in which R is a hydrocarbon radical with 1–12 carbon atoms, carried out in the presence of a catalyst system comprising (A) a solid catalyst component which comprises Mg, halogen, an electron donor selected from ethers, esters, or amines, and Ti atoms in an oxidation state such that the weight percentage ratio between Ti (red) /Ti (tot) ranges from about 0.05 to about 1 wherein Ti (red) is the weight percentage on the solid catalyst component of the Ti atoms having a valence less than 4 and Ti (tot) is the weight percentage on the solid catalyst component of all the Ti atoms, and (B) an Al-alkyl compound; wherein a molar ratio of Ti (tot) /electron donor is higher than 1.