Polyethylene molding material and pipe produced therewith with improved mechanical properties

US6770341B1 · kind B1 · utility

Assignee

• Basell Polyolefine GmbH · DE

Inventors

• Ludwig Bohm · Mainz, DE
• Joachim Berthold · Prien am Chiemsee, DE
• Johannes-Friedrich Enderle · Frankfurt, DE
• Elke Damm · Bad Vilbel, DE
• Ulrich Schulte · Kelkheim, DE

Key dates

• Filing date: Dec 17, 2001
• Grant date: Aug 3, 2004
• Expiry date: Jan 2, 2022

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/1397
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

A polyethylene molding material has a bimodal molecular weight distribution with an overall density of ≧0.948 g/cm3 and a melt flow index MFI190/5 of ≦0.2 dg/min. The molding material comprises from 35 to 65% by weight of low-molecular-weight ethylene hompolymer A having a viscosity number VNA in the range from 40 to 90 cm3/g, a melt flow index MFI190/2.16 A in the range from 40 to 2000 dg/min and a density dA of ≧0.965 g/cm3. Also included is from 35 to 65% by weight of high-molecular-weight ethylene copolymer B having a viscosity number VNB in the range from 500 to 2000 cm3/g, a melt flow index MFI190/5 B in the range from 0.02 to 0.2 dg/min and a density dB in the range from 0.922 to 0.944 g/cm3.