PROCESS FOR THE PREPARATION OF A POLYPROPYLENE MOLDING COMPOSITION

摘要

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 for- mula I (see formula I) 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.