Polymeric microfibrous filter sheet, preparation and use

US4617124A · kind A · utility

Assignee

• Pall Corporation · US

Inventors

• David B. Pall · Glen Cove, US
• Peter J. Degen · Woodbury, US
• Thomas C. Gsell · Dillingen/Saar, DE

Key dates

• Filing date: Jul 13, 1982
• Grant date: Oct 14, 1986
• Expiry date: Jul 13, 2002

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B01D2239/1291
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

Microfibrous, polymeric filter sheets and filter elements prepared therefrom comprised of a normally hydrophobic, microfibrous, polymeric web, wherein the surfaces of the microfibers making up the web are coated with a cured, precipitated, cationic, thermosetting binder resin or polymer. The filter sheet is further characterized by being hydrophilic and having a positive zeta potential. The process for preparing such filter sheets comprises four steps: PA0 (1) applying a first solution or dispersion of a precipitating agent to a hydrophobic web to at least partially wet the web; PA0 (2) applying a second solution of the binder resin or polymer to the wetted web of step (1); PA0 (3) working the wetted web of step (2) to mix the first and second solutions, thereby facilitating the precipitation of the binder resin or polymer and the distribution of the precipitated binder resin or polymer as a coating on the surface of the microfibers making up the worked web; and PA0 (4) drying and curing the coated web of step (3) to form the desired filter sheets. The filter sheets have enhanced mechanical strength, are hydrophilic, have positive zeta potentials over the pH range of from about 3 t…