Patent GB-580506-A (GB)
Title: Improvements in or relating to photographic materials
IPC: G03C1/38
Filed: 1944-07-19
Abstract: 580,506. Photographic emulsions. HART, J. A. H., and LEE, E. W. July 19, 1944; No. 13775. [Class 98 (ii)] A photographic emulsion comprises silver halide dispersed in gelatin in an aqueous medium containing at least 2 per cent on the weight of the gelatin of an anionic wetting agent and between 30 and 70 per cent on the weight of the liquid medium of a water-miscible organic liquid. The emulsion may be coated on a surface by spraying with a compressed-air operated spray gun. The organic liquids may be ethyl, methyl, or isopropyl alcohol, methyl acetate, acetone, or 1 : 4-dioxane, and a mixture may be employed. The anionic wetting agent may be a soluble salt of a long-chain alkyl carboxylic acid, e.g. oleic, ricinoleic, linoleic, stearic, or palmitic, a soluble salt of a long-chain alkyl sulphonic acid, a soluble salt of a sulphated higher fatty alcohol, e.g. of lauryl hydrogen sulphate or oleyl hydrogen sulphate, a soluble salt of a sulphated secondary alcohol containing at least 8 carbon atoms in the chain, a soluble salt of an alkylated aromatic sulphonic acid, e.g. of alkyl benzene sulphonic acids, of alkyl naphthalene sulphonic acids, or of alkylated hydroxydiphenyl sulphonic acids, or a soluble salt of a long-chain alkyl ester of sulphated succinic acid. Alkali metal (e.g. Na or K), ammonium, or amine (e.g. triethanolamine or cyclohexylamine) salts may be used, or where sufficiently soluble, the free acids may be used. The compounds may contain amino residues in the anion, e.g. sodium oleoylaminoethanesulphonate. Commercial compounds are those sold under the Registered Trade Marks " Agral N," "Dispersol L," " Gardinol," " Igepon T," " Lissapol A and C," " Lissatan A," " Nekal A and BX," " Perminal W," and sulphonated " Lorol TA, NH and CY " and " Ocenol," and the names Aerosol OT, Aresklene 375, Lohrinol, Santomose D, Teepol X, and Tergitol 4 and 7. An anionic, cationic, or non-ionic wetting agent may be incorporated in the surface to be coated by incorporation in the substance of the article or by application in aqueous or non-aqueous solution by flowing, dipping, brushing, beading or spraying. A subbing layer may be first applied to the article to be sprayed and may include the wetting agent. For a cellulose nitrate or polymerized methyl methacrylate support, a dispersion of gelatin in an organic solvent may be used. Non-ionic wetting agents such as polyglycerol higher fatty acid esters or longchain alkyl sulphuric acids such as 1-methyltridecylsulphuric acid, and the compounds " Lubrol W " and " Lissapol N " (Registered Trade Marks) may be used. To improve the contrast in dark-room illumination between the emulsion and the surface to be sprayed, a dye or pigment absorbing strongly in the darkroom light and preferably destroyed, dissolved or decolourised in processing may be added. In example 1, a 'solution of sodium 1-methyltridecylsulphonate and then ethyl alcohol are successively added to a melted gelatino silver halide emulsion, which is then cooled for use. In example 2, the composition comprises a gelatino silver halide emulsion, a solution of triethanolamine dodecyl sulphate and acetone. In example 3, Ink Blue for spraying in a yellow safelight or Acid Magenta for spraying in a green safelight is added to the composition of example 3. A subbing layer for a hydrophobic support comprises gelatin, salicylic acid, tetraglycerol monostearate and water. Regular or irregular surfaces of metal, wood, synthetic resins, or cellulose derivatives may be sprayed. Specifications 547,633 and 548,532 are referred to.