| 摘要 |
Catalyst systems of the Ziegler-Natta catalyst type, containing, as active constituents, a) a titanium-containing solid component which contains titanium, magnesium, halogen and a carboxylic acid ester, and, as cocatalyst, b) an aluminium compound and c) optionally further electron-donor compounds, characterised in that they contain, as the carboxylic acid ester in the solid component a), an ester of a benzophenone-2-carboxylic acid of the formula I <IMAGE> in which R<1> is a hydrogen atom, a C1-C15-alkyl group or a halogen atom. These catalyst systems are particularly suitable for the preparation of polypropylene and copolymers of propylene with minor amounts of other alpha , beta -unsaturated olefinic compounds having 2 to 12 carbon atoms. |
