PLANOGRAPHIC PRINTING PLATES

1,272,587. Photoconductive composition. AGFA-GEVAERT N.V. 7 Aug., 1969 [22 Aug., 1968], No. 40247/68. Heading H1K. [Also in Division C1] A photo-sensitive article comprises lead (II) oxide grains dispersed in a binder which grains contain a crystalline mixture of the orthorhombic and the tetragonal modification of lead (II) oxide and wherein the tetragonal type is present from at least 20 wt. per cent to 95 wt. per cent. An electrophotographic element sensitive to X-rays or visible light may be made by dry or wet grinding yellow orthorhombic lead (II) oxide until the desired proportion of tetragonal lead (II) oxide is formed, adding a styrenated alkyd resin in toluene, mixing and coating the mixture on an aluminium-coated paper. The support may also be a plate of Al, Cu, Sn, Fe or Pb, a vacuum-deposited layer of Ag or Al, a conductive polymer, a dispersion of carbon or metal particles in resin, or paper impregnated with a conductive compound. Other binding agents are also specified. The electrophotographic element may be built up of four successive layers of lead oxide in resin. The grinding process may be done in the presence of toluene, white spirit, hexane or ethyl acetate. A dispersing agent such as an acid ester of a phosphorus oxyacid may be used during grinding.