Integrally asymmetrical polyolefin membrane for gas exchange

US6409921B1 · kind B1 · utility

Assignee

• Membrana GmbH · DE

Inventors

• Marcus Müller · Arnhem, NL
• Erich Kessler · Kelsterbach, DE
• Ralf R. Hornscheidt · Heiligenhaus, DE
• Frank Wiese · Huntsville, US
• Armin Lang · Schwäbisch Gmünd, DE

Key dates

• Filing date: Feb 28, 2000
• Grant date: Jun 25, 2002
• Expiry date: Feb 28, 2020

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N27/404
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

Process for producing hydrophobic polyolefinic membranes for gas exchange via thermally induced liquid-liquid phase separation is disclosed. A solution of at least one polyolefin in a solvent system, of a compound A and a compound B having a viscosity less than 60 mPa s, is extruded to form a shaped object. The compound A is a solvent and compound B preferably a non-solvent of the polymer, and the boiling point of compound A is at least 50&deg; C. higher than that of compound B. After the shaped object leaves the die, at least one surface thereof is subjected to an atmosphere promoting evaporation of compound B, and the shaped object is subsequently cooled until the phase separation and solidification of the high-polymer-content phase take place. The integrally asymmetrical membrane producible in this manner has a porosity of greater than 50% to 75% by volume, a sponge-like, open-pored, microporous support layer without macrovoids and on average isotropic pores, and at least one separation layer with pores <100 nm, if any. The membrane is preferably used for blood oxygenation.