Integrally asymmetrical polyolefin membrane

US6497752B1 · kind B1 · utility

Assignee

• Membrana GmbH · DE

Inventors

• Erich Kessler · Kelsterbach, DE
• Thomas Batzilla · Miltenberg, DE
• Friedbert Wechs · Bad Mergentheim, DE
• Frank Wiese · Huntsville, US

Key dates

• Filing date: Aug 24, 2001
• Grant date: Dec 24, 2002
• Expiry date: Aug 24, 2021

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B01D2325/022
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

Process for producing integrally asymmetrical hydrophobic polyolefinic membranes with a separation layer, in particular for gas exchange, via thermally induced liquid-liquid phase separation. A solution of at least one polyolefin in a solvent system containing a compound A and a compound B is extruded to form a shaped object. Compound A is a strong solvent and compound B a weak non-solvent for the polymer. After leaving the die, the shaped object is cooled using a solid or liquid cooling medium, which does not dissolve the polymer and does not react chemically with it, 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 30% to 75% by volume, a sponge-like, open-pored, microporous support layer without macrovoids and on average isotropic pores, a separation layer on at least one of its surfaces with pores <100 nm, if any, and a gas separation factor &agr;(CO2/N2) of at least 1. The membrane is preferably used for blood oxygenation.