Process for preparing polypropylene molding compositions.
摘要
A propylene block copolymer of high flowability and very good low-temperature toughness is obtained in high yield if the polymerisation of the propylene and the comonomers is carried out using a catalyst comprising a chiral metallocene of the formula I <IMAGE> containing bridges, and an aluminoxane. The polymerisation is carried out in two steps, a crystalline propylene polymer being prepared in liquid monomers in the first step, and a copolymer being prepared in the gas phase in the second step.
