CATALYST FOR THE POLYMERIZATION OF OLEFINS

摘要

The present invention relates to catalysts systems for the polymerization of ethylene and its mixtures with olefins CH2=CHR, wherein R is an alkyl, cycloalkyl or aryl radical having 1-12 carbon atoms, comprising (A) a solid catalyst component comprising Ti, Mg, halogen, and optionally an electron donor compound in a donor/Ti molar ratio lower than 3, (B) an aluminum alkyl compound and (C) a silicon compound of formula XmR1 nSi(OR2)4-(m+n) in which X is bromine or fluoride or a halogen containing hydrocarbon group, R1 is a C1-C1O aliphatic or alicyclic group, R2 is C1-C1O alkyl group, m is an integer ranging from 1 to 3, n is 0 or 1 provided that the sum m+n is not higher than 3. The catalyst of the invention is suitably used in (co)polymerization processes of ethylene to prepare (copolymers having narrow Molecular Weight Distribution (MWD) and high activity.