Hoechst Aktiengesellschaft

Hartmut Kondoch

Andreas Winter

Jurgen Rohrmann

Michael Schreck

Volker Dolle

Martin Antberg

Walter Spaleck

Process for the preparation of a polypropylene molding composition A propylene block copolymer having good flow properties and a very good low temperature impact strength is obtained in a high yield if a catalyst which consists of a chiral metallocene, containing a bridge, of the formula I ##STR1## and an aluminoxane is used for the polymerization of propylene and the comonomers. The polymerization is carried out in two stages, a crystalline propylene polymer being prepared in the first stage.

Process for the preparation of a polypropylene molding composition

A propylene block copolymer having good flow properties and a very good low temperature impact strength is obtained in a high yield if a catalyst which consists of a chiral metallocene, containing a bridge, of the formula I ##STR1## and an aluminoxane is used for the polymerization of propylene and the comonomers. The polymerization is carried out in two stages, a crystalline propylene polymer being prepared in the first stage.

A propylene block copolymer having good flow properties and a very good low temperature impact strength is obtained in a high yield if a catalyst which consists of a chiral metallocene, containing a bridge, of the formula I ##STR1## and an aluminoxane is used for the polymerization of propylene and the comonomers. The polymerization is carried out in two stages, a crystalline propylene polymer in liquid monomers being prepared in the first stage and a copolymer in the gas phase being prepared in the second stage.

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Frankfurt am Main, Germany

Hartmut Kondoch