TITLE: POLYAMIDE MEMBRANE AND PROCESS FOR ITS PRODUCTION
European Patent EP0090483
 B1

ABSTRACT:
Abstract of EP0090483
Surface modified, skinless, hydrophilic, microporous, polyamide
membranes are formed by preparing a casting solution comprised of (A) a
casting resin system comprised of (a) an alcohol-insoluble polyamide
resin, and (b) a cationic, water-soluble, quaternary ammonium,
thermosetting, membrane surface modifying polymer, and (B) a solvent
system in which the casting resin system is soluble; inducing
nucleation of the casting solution by controlled addition of a
non-solvent for the casting resin system under controlled conditions to
obtain a visible precipitate of casting resin system particles, thereby
forming a casting composition; spreading the casting composition on a
substrate to form a thin film; contacting and diluting the film of the
casting composition with a liquid non-solvent system for the casting
resin system, thereby precipitating the casting resin system from the
casting composition in the form of a thin, skinless, hydrophilic,
surface modified, microporous, polyamide membrane; and washing and
drying the membrane. The membranes of this invention are characterized
by having fine pore ratings, the surfaces thereof being substantially
completely covered by the modifying polymer, a positive zeta potential
in alkaline media, and for those with moderate or low levels of surface
modifying polymer present, a time to reach an effluent resistivity of
14 megaohms/cm under the Resistivity Test of 10 minutes or less. They
have greatly enhanced filtration efficieny over a broad pH range with a
variety of contaminants, including very fine negatively charged
particles, bacteria and endotoxins.

INVENTORS:
Gsell, Thomas Charles
Joffee, Irving Brian
Degen, Peter John

APPLICATION NUMBER: EP19830300518
PUBLICATION DATE: 07/30/1986
FILING DATE: 02/02/1983

ASSIGNEE: PALL CORPORATION
INTERNATIONAL CLASSES: C08L77/00; B01D39/16; B01D61/22; B01D67/00; B01D71/56; C08J9/28;
(IPC1-7): B01D13/04
EUROPEAN CLASSES: B01D71/56; B01D67/00K14; B01D67/00K14B