| abstract |
A microporous, polymeric film is prepared by dissolving methylene-chloride-soluble, film-forming polymers completely in methylene chloride. Then an aqueous phase is prepared containing non-methylene-chloride-soluble, water-soluble thickeners and, if desired, additives, and brought to a viscosity of about 0.07 to 0.5 Pa s. The aqueous phase is then dispersed in the polymer solution and the resultant paste is spread onto a support material or intermediate support, the methylene chloride is evaporated, the resultant membrane is transferred to the actual support, and finally the water is removed by drying. |