Ultrafiltration membrane of polyamide

US4595503A · kind A · utility

Assignee

• Akzo N.V. · NL

Inventors

• Erich Schindler · Unterweissach, DE
• Franz Maier · Munich, DE

Key dates

• Filing date: Oct 10, 1984
• Grant date: Jun 17, 1986
• Expiry date: Oct 10, 2004

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B01D71/56
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

A membrane is disclosed of polyamide, a copolyamide or a mixture of polyamides, suitable for ultrafiltration and composed of an ultrafiltration skin and a backing layer. The pore size in the backing layer increases with distance from the ultrafiltration skin. The membrane is prepared by dissolving a polyamide in at least 75% formic acid, applying a casting solution, containing about 12-22% by weight polyamide and about 1-7% by weight polyethylene glycol in formic acid which has been brought to a temperature of below about 18.degree. C., as a thin layer onto a carrier foil resistant to the components of the solution, introducing the casting solution on the carrier foil into a precipitation and washing bath, withdrawing the casting solution as a coagulated and washed membrane from the carrier foil, stretching in at least one direction and subsequently drying this coagulated and washed membrane.