| abstract |
Catalyst systems of the Ziegler-Natta type containing, as active components, n n a) a titanium-containing solids component which contains titanium, magnesium, halogen and a norbornadienecarboxylic ester of the general formula I n<IMAGE>n as an electron donor, in which R<1> and R<2> denote C1-C8-alkyl groups or 5-membered to 7-membered cycloalkyl groups which in turn may carry C1-C10-alkyl groups, n b) an aluminium component and n c) a further electron donor component. n n<??>These catalyst systems are suitable in particular for the preparation of polypropylene and copolymers of propylene with minor amounts of other alpha ,ss-unsaturated olefin compounds having 2 to 8 C atoms. |