Propylene random copolymer and process for the production thereof

• Main Authors: Jaaskelainen, Pirjo, Hafner, Norbert, Pitkanen, Paivi, Gahleitner, Markus, Tuominen, Olli, Toltsch, Wilfried
• Format: Patent
• Language: English
• Published: 25.08.2009

The present invention relates to a process for preparing a propylene random copolymer comprising polymerization of propylene with a comonomer, said comonomer being ethylene or an α-olefin comprising at least four carbon atoms, in the presence of a catalyst in a multistage process comprising polymerization of propylene with a comonomer in a first reaction zone including at least one slurry reactor to give a first polymerization product, transferring said first product to a second reaction zone including at least one gas phase reactor and polymerisations of propylene with a comonomer in said gas phase reactor in the presence of said first polymerization product, wherein the temperature in the gas phase reactor is at least 10° C. higher than in the slurry reactor and to a polymer obtainable by this process. Furthermore, the invention relates to a propylene random copolymer prepared by copolymerization of propylene with a comonomer wherein the distribution of the comonomer determined according to the TREF method is multimodal, preferably bimodal, a propylene random copolymer prepared by copolymerization of propylene with a comonomer wherein the copolymer is having an elution interval determined according to the TREF method of 50° C. or more, a propylene random copolymer prepared by copolymerization of propylene with a comonomer, wherein the random copolymer is a unimodal polymer and the elution interval determined by the TREF method is given by the equation Y≦4.5·m+16 wherein Y is the elution interval in ° C. and m is the percentage of ethylene in the copolymer in wt. %, and to the use of such a copolymers for the production of a film, of an article by blow moulding or injection moulding, of a fiber or of a pipe.