| 摘要 |
762,080. Coated semi-permeable membranes. YARDNEY INTERNATIONAL CORPORATION. Oct. 15, 1952 [Oct. 17, 1951; May 2, 1952], No. 25904/52. Class 140. [Also in Group XXXVI] A battery separator consists of a semipermeable membrane of regenerated cellulose or other material to which is applied a coating of a thermoplastic substance incorporating an ion exchanger. Cation or anion exchangers may be used in the coating and if the exchanger is a film-forming material it may be applied directly to the semi-permeable membrane. The coating may also include a polyacrylate. The coating may consist of polystyrene, polyvinyl resins or styrene and butadiene copolymers and may be treated with sodium or potassium chloride to reduce its electrical resistance. The ion exchanger may consist of a sulphonated styrene or other resin or of sulphonated casein, zein, polyvinyl alcohol or acetate or regenerated cellulose. In an example casein is dissolved in sulphuric acid, precipitated with potassium hydroxide and the precipitate dissolved in weak sulphuric acid. The semi-permeable membrane which may. consist of regenerated cellulose is then dipped in the solution. Instead of casein zein may be dissolved in sulphuric acid in the presence of silver oxide as a catalyst. In another example the membrane is dipped in a solution obtained by dissolving polystyrene in sulphuric acid and removing the free acid by dialysis. In a further example the membrane is dipped in an emulsion of polyvinyl acetate containing sodium or potassium methacrylate and a sulphonated styrene cation exchange resin.
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