The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 24, 1982
Filed:
May. 11, 1981
Canadian Patents & Development Ltd., Ottawa, CA;
Abstract
An improvement in the method of casting a reverse osmosis or ultrafiltration polymeric membrane on a wall of porous support having a first, high pressure side under service conditions, and a second, low pressure side under service conditions, wherein the first side is coated wih a cellulose ester casting solution to at least partially impregnate the support, solvent carrier of the casting solution is partially evaporated to leave a residue, and then residues adjacent the first and second sides are gelled with a gelation liquid comprising a monohydric alcohol. The improvement comprises gelling the residue adjacent the first side with a gelation liquid which is separate from that used to gel the residue adjacent the second side, and the monohydric alcohol mole fractions of the separate gelation liquid, and their temperatures during gelation, are chosen so that relatively larger pores are formed towards the second side of the porous support. The method is particularly useful for casting tubular, polymeric membranes anchored to the inner surface of a porous, tubular support and where the relatively larger pores are adjacent the outer surface of the porous support.