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- and/or polyester as internal electron donor ED, comprising the steps of:

• (i) reacting in solution at least one magnesium compound (a), selected from the group consisting of a dialkyl magnesium R2Mg, an alkyl magnesium alkoxide RMgOR, wherein each R is a similar or different C1-C20 alkyl, and a magnesium dihalide MgX2, wherein X is a halogen, with at least one alcohol (b) selected from the group consisting of at least one polyhydric alcohol R′(OH)m, and a mixture of at least one monohydric alcohol R′OH and at least one polyhydric alcohol R′(OH)m, wherein each R′is the same or different 1-valent or, respectively, m-valent C1-C20 hydrocarbyl group and m is an integer from 2 to 6, to give a first intermediate (ab),
• (ii) reacting in solution said first intermediate (ab) with at least one dicarboxylic acid dihalide (c) which forms essentially all of said carboxylic acid di-, oligo- and/or polyester 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 a second intermediate (abc), and
• (iii) reacting said second intermediate (abc) with at least one titanium tetrahalide TiX″4(d) wherein X″ is a halogen,
• (iv) recovering by precipitation said catalyst component in crude form or a precursor of said catalyst component, and
• (v) optionally washing said crude catalyst component or said precursor, to obtain said catalyst component.