ELASTOMERIC PROPYLENE COPOLYMERS AND PROCESS FOR MANUFACTURING THEM IN GAS PHASE

摘要

22935-1064 Novel elastomeric copolymers of propylene with ethylene and/or 1-butene and optionally one or more alpha-olefins containing from 5 to 12 carbon atoms are prepared using a catalyst system that is highly active and stereospecific. A prepolymer is first prepared in the presence of a particular catalyst of the Ziegler Natta type that has a support based on magnesium dichloride. In a second stage gas phase copolymerization the prepolymer is contacted with a mixture comprising propylene, ethylene and/or 1-butene and optionally an alpha-olefin containing from 5 to 12 carbon atoms, propylene constituting from 20 to 80% of the total volume of the olefins to be copolymerized.