High molecular weight, medium density polyethylene

US6770715B2 · kind B2 · utility

Assignee

• Equistar Chemicals, LP · US

Inventors

• Philip J. Garrison · Houston, US
• Lawrence R. Wallace · Evansville, US
• Danny L. Wise · Kings Mills, US
• James H. Meas, Jr. · Cincinnati, US
• Leonard V. Cribbs · Hamilton, US
• Jean A. Merrick-Mack · Sharonville, US
• Paula L. Nygard · Bay City, US

Key dates

• Filing date: Sep 12, 2002
• Grant date: Aug 3, 2004
• Expiry date: Sep 12, 2022

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S526/905
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

A high molecular weight, medium density polyethylene (HMW, MDPE) is disclosed. The polyethylene comprises from about 85 to about 98 wt % of recurring units of ethylene and about 2 to about 15 wt % of a C3-C10 &agr;-olefin. It has a density from about 0.92 to about 0.944 g/cc, a melt index MI2 from about 0.01 to about 0.5 dg/min, and a melt flow ratio MFR from about 50 to about 300. It has a multimodal molecular weight distribution comprising a high molecular weight component and a low molecular weight component. The low molecular weight component has an MI2 from about 50 to about 600 dg/min and a density from about 0.94 to about 0.97 g/cc. A process for making the medium density polyethylene is also disclosed. The process uses a Ziegler catalyst and applies multiple reaction zones.