Patent ID: 6159369
Filing Date: 2000-12-12
Classification: B01D

Abstract:
A process for partial modification of porous, hydrophilic filter membranes said process comprising soaking areas of a porous hydrophilic filter membrane intended to be imbedded in hydrophobic polymer material with a solution of a hydrophilizing agent, so that the porous hydrophilic filter membrane is saturated with the solution in predetermined areas to result in a saturated hydrophilic filter membrane, wherein said predetermined areas are more hydrophilic than other areas of the filter membrane, and substantially immediately thereafter washing and drying the saturated hydrophilic filter membrane, wherein prior to said soaking said porous hydrophilic filter membrane is hydrophilic to such an extent that, after one minute of having been placed on a substantially still water surface at 25.degree. C., a surface of said porous hydrophilic filter that had come into contact with water is substantially completely wetted with water, wherein said hydrophilizing agent comprises a member selected from the group consisting of polyvinyl pyrrolidone, a polyvinyl pyrrolidone-copolymer, a peroxodisulfate and mixtures thereof, in a sufficient amount dissolved in a water/ethanol mixture, so that hydrophilic, modified areas of said filter membrane exhibit a hydrophilicity at least twice as high as other areas of said filter membrane.