GB387170A - Improvements in and relating to the manufacture of intaglio printing rollers or cylinders - Google Patents

Abstract

387,170. Electrodeposition of copper. LANGBEIN - PFANHAUSER - WERKE AKT.-GES., 76, Torgauer Strasse, Leipsic, Germany. April 8, 1932, No. 10055. Convention date, Jan. 27. [Class 41.] An intaglio printing-roller formed of or coated with nickel, cobalt, or an alloy of nickel and cobalt, with or without iron, copper, or the like, and having thereon a copper etching layer which is mechanically strippable, is formed by depositing on the smooth surface of the cylinder a layer of copper of which the portion first applied is of such different texture from that ordinarily produced by electrodeposition that it is less strongly adherent than the remainder of the layer which is thereafter applied by known methods of electrodeposition. The body of the cylinder may consist of iron, steel, aluminium, brass, copper, or bronze having an outer surface of polished and degreased nickel, cobalt, &c., and to produce the first portion of the deposit this cylinder is rotated for a short time under a current density of 3 to 5 amps. per square decimetre in a bath containing 75 to 100 grs. of potassium copper cyanide and 20 grs. of caustic soda per litre, such that the bath contains little or no cyanide not in the form of complex metal salts, and this initial layer is then increased to a thickness of À1 to À15 mms. by means of a normal copper-plating bath containing 220 grs. copper sulphate and 15 grs. sulphuric acid per litre, and with a current density from 3 to 10 amps. per square decimetre. Alternatively the cylinder may be used for a short time as the anode of a normal acid copperplating bath and may then be coated by electrodeposition in known manner in the same or another bath. To promote the passivation of the surface when using the cylinder as an anode 2 to 10 grs. of chromium sulphate per litre may be added.