Process for the preparation of a polypropylene molding composition

US5280074A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Michael Schreck · Frankfurt, DE
• Andreas Winter · Königstein, DE
• Walter Spaleck · Bocholt, DE
• Hartmut Kondoch · Frankfurt am Main, DE
• Jurgen Rohrmann · Kelkheim, DE

Key dates

• Filing date: Oct 13, 1992
• Grant date: Jan 18, 1994
• Expiry date: Oct 13, 2012

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S526/943
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

A propylene block copolymer having good flow properties and a very good low temperature impact strength is obtained in a high yield if a catalyst which consists of a chiral metallocene, containing a bridge, of the formula I ##STR1## and an aluminoxane is used for the polymerization of propylene and the comonomers. The polymerization is carried out in two stages, a crystalline propylene polymer in liquid monomers being prepared in the first stage and a copolymer in the gas phase being prepared in the second stage.