Catalyst component comprising magnesium, titanium, a halogen and an electron donor, its preparation and use

A process for the preparation of an olefin polymerization catalyst component comprising a magnesium dihalide, a titanium tetrahalide, and a dicarboxylic acid di-, oligo- or polyester as internal electron donor ED, comprising the steps of:

• (i) providing a magnesium compound (ab) containing an alkoxy moiety, selected from the group consisting of a magnesium dialkoxide, a complex containing a magnesium dihalide and an alcohol, and a complex containing a magnesium dihalide and a magnesium dialkoxide, and
• (ii) reacting said magnesium compound (ab) with at least one dicarboxylic acid dihalide (c) which forms said dicarboxylic acid di-, oligo- or polyester as internal donor ED and has the formula (1):
• wherein each R″ is a similar or different C1-C20 hydrocarbyl group or both R″:s form together with the two unsaturated carbons of the formula a C5-C20 aliphatic or aromatic ring, and X′ is a halogen, to give an intermediate (abc),
• (iii) reacting said intermediate (abc) with at least one titanium tetrahalide TiX″4 (d) wherein X″ is a halogen,
• (iv) recovering said catalyst component in crude form or recovering a precursor of said catalyst component, and
• (v) optionally washing said crude catalyst component or said precursor, to give said catalyst component, and
• by adding and reacting in connection with the above step (ii) or (iii) at least one reactive halogenated hydrocarbon (e) of the formula (2)
• R′″(X′″)n (2)
• wherein R′″ is an n-valent C1-C20 hydrocarbyl group, X′″ is a halogen and n is an integer selected from 1, 2, 3 and 4 and wherein said reactive halogenated hydrocarbon (e) is added in an amount corresponding to a molar ratio Mgtotal added/(e) of between 1:0.2 and 1:20.