Catalyst components and catalysts for polymerizing olefins

Claim 1

Process for preparing components of catalysts for the polymerization of olefins which comprises mixing the solid product of the reaction of: (a) a halogenated Ti-compound containing at least a Ti-halogen bond, and (b) an electron-donor compound which does not contain active hydrogen atoms (ED) reacted as such or as a complex with product (c) prepared without cogrinding of the product (c) with compound (ED), and employed in such amount and under such conditions, that from 0.2 to 4 moles of compound (ED) per gram atom of Ti of compound (a) are present in the catalyst component; with (c) the solid product prepared without cogrinding, of the reaction between at least one electron-donor compound containing active hydrogen atoms (HED), selected from among the group consisting of aliphatic, cycloaliphatic and aromatic alcohols and thioalcohols having 1 to 20 C, phenols and thiophenols having 6 to 20 C and silanols having 1 to 20 C, and a Mg dihalide, or a complex of said Mg dihalide with a compound (ED), obtained by reaction of halogenating agents other than the Ti compounds of (a), with an organic Mg compound of formula: R.sub.m MgX.sub.n in which R is an alkyl, alkenyl, cycloalkyl or aryl radical containing 1 to 20 C, or a group OR, X is a halogen or a radical R, OR or COX' in which R has the meaning stated, X' is halogen, 0<m≦2, 0≦n<2, and n+m is 2, product (c) being reacted as such, without any intermediate pretreatment with an Al-alkyl compound.