GB538245A - Improved method of producing light-sensitive layers sensitised by means of an iron salt and layers made thereby - Google Patents

Abstract

538,245. Photographic materials containing light-sensitive iron salts. PHILIPS LAMPS, Ltd. April 8, 1940, No. 6348. Convention date, April 11, 1939. [Class 98 (ii)] A light-sensitive layer is produced on a support, preferably water-impermeable, by suspending a water-soluble light-sensitive iron salt in a solution of a water-insoluble binding agent in a volatile organic liquid, in which is preferably also suspended a substance necessary for the development of the image, and applying the dispersion to the support and evaporating the organic liquid. The substance to be suspended and the dispersion medium may be jointly ground together in a ball mill. In an example an aluminium plate is coated with a suspension of ferric ammonium citrate and potassium ferricyanide in a solution of cellodammar resin in carbon tetrachloride, the solvent is partly evaporated at 80‹C., the excess suspension is poured off, and the solvent is completely evaporated. After exposure under a negative and rinsing with water a blue positive image is obtained. In another example the suspension contains in place of potassium ferricyanide, silver nitrate and tartaric citric, and oxalic acids. A greyish black image is obtained. In another example the aluminium plate is coated with a suspension of ferric ammonium oxalate, potassium ferric citrate, and oxalic acid in a solution of cellodammar resin in benzene. After exposure, bathing is effected in a 1 per cent. solution of ammonium persulphate in water followed by rinsing with water. In a further example, the plate is coated with a suspension of ferric ammonium citrate, silver nitrate, and tartaric acid in a solution of polyvinyl acetate in ethanol. The finished images may be protected by a layer of celluloid lacquer. Other supports referred to are metals other than aluminium, glass, cellulose acetate, rubber, rubber derivatives and paper. Other binding agents referred to are polymerized hydrocarbons such as polystyrene, polymerized unsaturated fatty acid esters such as derivatives of acrylic acid and its homologues, viny acetic acid, and resins and gums such as ester gum, mastic, and colophony. Other volatile organic solvents referred to are toluene and trichlorethylene. Specification 166,063, [Class 98 (ii)], is referred to.