GB1068622A - Electrophotographic reproduction - Google Patents

Abstract

1,068,622. Electrophotography employing electrolytic development. KODAK Ltd. April 8, 1964 [April 8, 1963], No. 14459/64. Addition to 1,006,113. Heading G2H. A method of photographic reproduction comprises passing a direct current through an electrolyte in contact with the positive electrode and a photo-conductive layer which has been or is being exposed to a light image and is carried by a conducting layer connected as cathode, the electrolyte being a dilute aqueous solution containing ionizable magnesium and manganese compounds so that an imagewise deposit of the metal hydrioxides or hydrated oxides occurs on the photo-conductive layer n the exposed areas, and thereafter treating the deposited image with aqueous silver nitrate. The electrolyte also may comprise cobalt ions, or cobalt ions and/or cerium ions may be added to the silver nitrate solution. A blue dyed image may be obtained by incorporating a blue dye in the electrolyte so that dye is deposited together with the hydroxide image. Alternatively, the deposited image may be treated with a dye bath before treatment with silver nitrate or the dye may be incorporated into the silver nitrate bath. Ions of chromium, aluminium, bismuth, uranium or thorium also may be added to the electrolyte and the use of ferric ions is mentioned. In the examples, a layer of zinc oxide dispersed in an insulating binder, such as a styrene/butadiene copolymer and coated on an aluminium foil/paper laminate is exposed and simultaneously or subsequently developed electrolytically using an electrolyte comprising manganous, cobaltous and magnesium nitrates and with a potential of 20 or 30 volts between the aluminium backing and a stainless-steel frame acting as a developer retainer. The deposited image is swabbed with silver nitrate solution and the dried print may be lacquered with an acrylic ester resin. The silver nitrate solution may contain diethanolamine, and compounds such as 3-mercapto-1, 2,4- triazole, 2-thiobarbituric acid, 2-mercaptothiazoline, 5-mercapto- 1 -phenyl tetrazole, 5- methyl-oxazoline-2-thiol or 7, 13 dithianondecane- 1, 19-bis (pyridinium p-toluene sulphonate) may be included in the electrolyte. Reference has been directed by the Comptroller to Specification 963, 539.