GB1143686A - - Google Patents

Abstract

1,143,686. Electro-deposition of resins. FORD MOTOR CO. Ltd. Nov.22, 1967 [Dec.6, 1966], No.53073/67. Heading C7B. In a method of coating an electrically conductive object in an aqueous bath having intimately dispersed therein an organic resin having ionized sites thereon, which method comprises immersing the object within the bath and applying a difference in electrical potential between the object and a counter-electrode, of sufficient value to effect deposition of a coating of resin on said object, and removing the coated object from the bath; a portion of the bath is placed between and in contact with an anode and a cathode maintained at an electrical potential difference which is below that required for deposition of the resin, but above that required to effect removal from the bath of the ionized inorganic materials which have accumulated with continued use. The purification treatment can be carried out either within the electrolyte bath during intervals in the coating process or by continuously withdrawing electrolyte to an adjacent cell for treatment. In the cell shown electrolyte is passed from the electro-coating tank 111 to subsidiary tank 140 via conduits 144, 150 to flow in countercurrent flow between anode 156 and cathode 142-1 or 142-2 respectively, the streams of electrolyte being separated by separators 158, 160 which prevent mixing of liquid on the opposite sides thereof but do not limit the conductivity between the anode 156 and the cathodes 142-1, 142-2, for instance textile sheets, e.g. glass fibre cloth, or porous plastics sheets, e.g. of polypropylene. Alternatively the subsidiary tank may form the cathode, an anode with multiple folds being positioned therein, and the voltage for both electro-deposition upon the workpieces in the main tank and purification of the electrolyte in the subsidiary tank originating from the same source Fig.1 (not shown).