Composite membranes and processes for their production

US5658669A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Olaf Althoff · Niedernhausen, DE
• Uwe Falk · Könnern, DE
• Ude Scheunemann · Bad Soden am Taunus, DE
• Werner Prass · Mainz, DE
• Werner Hickel · Ludwigshafen, DE

Key dates

• Filing date: May 5, 1995
• Grant date: Aug 19, 1997
• Expiry date: May 5, 2015

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/31544
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

A composite membrane comprises a porous carrier membrane (A) and a fluorine-containing permselective layer (C) which is a copolymer and has a thickness of 10 to 500 nm. The copolymer of layer (C) comprises PA1 a) 10 to 80 mol % of monomer units of a vinyl ester of the formula (I) ##STR1## in which R.sup.1, R.sup.2 and R.sup.3 are hydrogen, alkyl radicals, cycloalkyl radicals or aryl radicals, and these radicals together have at least 5 and not more than 30 carbon atoms, PA1 b1) 5 to 50 mol % of monomer units of a vinyl alcohol of the formula (II) ##STR2## in which R.sup.4 is the hydroxyl group and up to 10% of the groups R.sup.4 can be replaced by radicals of the formula OCOR.sup.5, in which R.sup.5 is methyl, ethyl or propyl, or PA1 b2) 5 to 50 mol % of monomer units of the formula (III) ##STR3## in which R.sup.6 is a straight-chain or branched alkylene radical having 1 to 6 carbon atoms, and PA1 c) at least 10 mol % of a fluoroolefin, the chains containing hydroxyl groups being crosslinked with one another, in particular by multifunctional isocyanates. The membrane can be employed, inter alia, for gas separation and pervaporation.