DE1621916

1,192,804. Electro-phoretic deposition. FORD MOTOR CO. Ltd. July 21, 1967 [Dec. 7, 1966], No. 33632/67. Heading C7B. In a process for electro-painting an electrically conductive object which is immersed in an aqueous electrolyte containing an organic resin having ionized sites intimately dispersed with an ionized dispersal assistant, whilst passing a direct current between the workpiece to be coated and a counterelectrode, a diffusion barrier which allows a flow of liquid to pass therethrough is placed between the workpiece and the counter-electrode to form a bathwithdrawal zone in contact with the counter-electrode, from which electrolyte of reduced paint concentration and increased concentration of dispersal assistant with respect to the electrolyte in the zone surrounding the workpiece is withdrawn, replenished and returned to the zone in contact with the workpiece. The embodiment shown, for use with a resin which is anodically deposited, comprises a metal tank 11 having a plastics lining 13 and containing an electrolyte bath 33; an overhead conveyor 39 for passing objects 35 to be coated through the bath; cathode assemblies 17 which comprise a wire screen cathode 17-3 and a diffusion barrier 17-4 and which are positioned adjacent the sides of the tank; and means 17-6 for withdrawal of catholyte from the zones associated with each cathode, the electrolyte withdrawn from each catholyte zone being passed to a catholyte collection unit 19 and thence via pump 23 to a paint dispersal unit 27 for replenishment, and thereafter being returned to the electrocoating bath 33 via conduit 31. Polycarboxylic acid resins dispersed with the acid of a watersoluble amino compound, e.g. a water soluble amine or ammonia, may be anodically deposited; and resins which may be cathodically deposited may be dispersed in the bath by addition of waterionizable acidic dispersal assistants, e.g. water soluble carboxylic acids or buffered phosphoric acid.