GB253091A - Improvements in or relating to the electrical deposition of organic materials - Google Patents

Abstract

253,091. Kodak, Ltd., (Assignees of Sheppard, S. E., and Eberlin, L. W.). June 8, 1925, [Convention date]. Indiarubber, preparation of.-Rubber is electrolytically deposited from an emulsion or suspension on to an anode of gas-permeable material the rear surface of which is subjected to a reduced pressure so that any oxygen formed in the anode zone is removed through the anode by suction. In the apparatus shown in Fig. 1, the material is deposited into a fabric 7 which is led by rollers 8, 9, 10 over a curved anode 4 of porous carbon forming one wall of a chamber 5 connected to a pump. The degree of suction is regulated in accordance with the current density. In the apparatus shown in Fig. 2 the anode density consists of a hollow cylinder 12 of porous carbon having a collar 13 supported on a bearing 11 and provided with a pulley 14 driven by a belt 15. The anode is provided with a contact ring 19 to which connection is made by a brush 20. The anode is closed at the top by a stopper 16 through which passes a stationary suction pipe 17, the connection being made air-tight by a stuffing-box 18. Cathodes 3 are arranged in a ring round the anode. The deposit may be vulcanized before or after removal. In a modification rubber is deposited on a fabric drawn over a rotating anode. The anode may consist of wire cloth of nickel or a nickel alloy having a mesh of 200 to 300 per inch; the cloth may be rolled to a comparatively smooth sheet. Strands of a non-conductor such as asbestos may be included. The removal of gas may be supplemented by incorporating reducing agents such as sodium or ammonium sulphite or thiosulphate in the emulsion. In an example, a rubber dispersion is prepared by mixing 1000 c.c. of a 5 per cent solution of rubber in benzol with 1000 c.c. of paraffin and 500 c.c. of sulphonated castor oil and stirring the mixture into 3000 c.c. of an aqueous solution containing 150 gms. of Castile soap a semulsifier. Aniline sulphate may be added before emulsification for the purpose of accelerating vulcanization. Vulcanizing agents may be added before emulsification or may be added to the emulsion in colloidal form, or may be omitted, vulcanization in this case being effected by subsequent treatment in a solution of sulphur in sulphur dichloride or otherwise. An ammonium soap is used as emulsifier when a coating of high electrical resistance is desired; the ammonia is driven off during vulcanization. The emulsifying agents may also consist of saturated or unsaturated compounds of fatty acids with alkali metals or ammonium, or of sodium phenol or cresolate with or without excess of cresol or cresylic acid. Direct current either constant or pulsating is employed. The voltage may be 110 and the current “ to ¢ amp. per sq. inch of anode surface.