Highly flowable propylene block copolymers

US7196140B2 · kind B2 · utility

Assignee

• Basell Poliolefine Italia S.r.l. · IT

Inventors

• Ulrich Dahn · Mannheim, DE
• Wolfgang Bidell · Mutterstadt, DE
• Hans-Jurgen Zimmermann · Bensheim, DE
• Roland Hingmann · Ladenburg, DE
• Joachim Rosch · Ludwigshafen, DE
• Gunther Schweier · Osthofen, DE
• Jurgen Oelze · Ludwigshafen, DE

Key dates

• Filing date: May 23, 2001
• Grant date: Mar 27, 2007
• Expiry date: Jul 4, 2021

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08F210/06
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

The invention relates to highly flowable propylene block copolymers that comprise 50 to 80 wt.-% of a propylene homopolymer and 10 to 70 wt.-% of a propylene copolymer having 5 to 50 wt.-% of a C2–C8 alk-1-ene polymerized into it that is different from propylene, and that are obtainable from the gaseous phase by a two-step polymerization by means of a Ziegler-Natta catalyst system. In a first polymerization step, the propylene is polymerized at a pressure of 10 to 50 bar, a temperature of 50 to 100° C. and an average dwelling time of the reaction mixture of 0.3 to 5 hours in the presence of at least 2.0% by volume, based on the total volume, of hydrogen. The propylene homopolymer obtained in said first polymerization step is transferred together with the Ziegler-Natta catalyst system into an intermediate container, expanded for 0.01 to 5 minutes to less than 5 bar and maintained at a temperature of 10 to 80° C. The pressure in the intermediate container is then increased by 5 to 60 bar by introducing under pressure a gaseous mixture, and the propylene homopolymer is then transferred to a second polymerization step together with the Ziegler-Natta catalyst system. In said second poly…