Multi-stage process for producing polyethylene with lowered gel formation

US8445599B2 · kind B2 · utility

Assignee

• Borealis AG · AT

Inventors

• Bill Gustafsson · Stenungsund, SE
• Jari Hatonen · Porvoo, FI
• Petri Rekonen · Helsinki, FI
• Markku Vahteri · Porvoo, FI
• Siw Bodil Fredriksen · Skien, NO
• Arild Follestad · Stathelle, NO
• Karl Isak Skau · Larvik, NO

Key dates

• Filing date: Oct 16, 2009
• Grant date: May 21, 2013
• Expiry date: Dec 2, 2029

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08L2205/03
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

The present inventions relates to a process for producing polyethylene compositions comprising polymerizing polyethylene resins in a cascaded multi-stage reaction in which the reaction steps are performed in at least two slurry phase reactors (A) and (B) and at least one gas phase reactor (C) which are arranged in series in any order wherein in reactor (A) a low molecular weight ethylene homo- or copolymer fraction having a MFR2 of 100 to 2000 g/10 min, in reactor (B) a low molecular weight ethylene homo- or copolymer fraction having an MFR2 of 100 to 2000 g/10 min, and in reactor (C) a high molecular weight ethylene copolymer fraction are polymerized, and further comprising a compounding step after polymerization, wherein the final polyethylene composition has a MFR21 of 3 to 50 g/10 min, the melt flow rates being determined according to ISO 1133.