GB1422652A - Electrorecording paper - Google Patents

Abstract

1422652 Electrosensitive recording sheets MATSUSHITA ELECTRIC INDUSTRIAL CO Ltd 2 Jan 1973 [5 April 1972 31 May 1972 14 Sept 1972] 257/73 Heading D2B An electrorecording sheet has a colourdeveloping layer containing a mixture of a white or pale-coloured electroconductive substance and a first component which reacts with a second component in the layer or with atmospheric oxygen to give a coloured record when heated by the Joule effect heat generated when current passes through the electroconductive substance when a voltage is applied across the layer. The electroconductive substance may be a semiconductor or a powder coated with an electroconductive film. Preferred electroconductive substances are CuI, SnO 2 , AgI, silica gel coated with a Nesa film, or particles of Zinc oxide, titanium dioxide, magnesium carbonate, calcium oxide, or lead carbonate coated with a film of zinc or aluminium. The colour-forming components may be (i) a leuco dye and a phenolic or organic acid colour developer, (ii) an organic spot reagent and organic metal salt, (iii) a redox indicator i.e. a substance which changes colour due to oxidation with atmospheric oxygen when heat is generated at the time of application of the electric current. The latter may be a leuco dye. The colour developing layer may be formed (a) on a support of paper, cloth, glass, or plastics film, (b) on an electroconductive support e.g. of paper incorporating carbon fibres or carbon powder, (c) on a support coated with an electro-conductive layer e.g. of a metal, CuI, or carbon, or (d) on a second colour-developing layer which is coated on a support provided with an electroconductive layer.