HIGH-MOLECULAR-WEIGHT POLYPROPYLENE HAVING A BROAD MOLECULAR-WEIGHT DISTRIBUTION

摘要

The invention relates to a high-molecular-weight copolymer comprising ethylene and propylene units which has an ethylene content in the range from 1 to 10% by weight, a melt flow rate MFR (230/5) of <5 dg/min and a molecular-weight distribution Mw/Mn in the range from 6 to 20. The invention also relates to a process for the preparation of the copolymer in the presence of a catalyst, an organoaluminum compound (B) and an organosilicon compound (C), in which the polymerization is carried out in two reaction steps, where the suspension medium in the first step is simultaneously the monomer, and a polypropylene having a viscosity of from 500 to 1400 ml/g which makes up a proportion of from 20 to 80% of the total polymer is prepared in the first reaction step.