Zieger-natta-type catalyst systems

摘要

Ziegler-Natta-type catalyst systems containing, as active constituents, a) a titanium-containing solid component which also contains magnesium, halogen and a carboxylic acid ester, and, as cocatalyst, b) an aluminum compound, wherein the carboxylic acid ester in the solid component is a diester of a carboxylic acid of the formula Ia or Ib <IMAGE> (Ia) <IMAGE> (Ib) where R1, R2, R3 and R4 are identical or different and are hydrogen, C1- to C15-alkyl, C7- to C15-alkylaryl, or 5- to 7-membered cycloalkyl, which may itself carry C1- to C10-alkyl groups, are particularly suitable for the preparation of polypropylene and copolymers of propylene containing minor amounts of other alpha , beta -unsaturated olefinic compounds having from 2 to 12 carbon atoms.