Patent GB-592676-A (GB)
Title: Improvements in light-sensitive photographic elements
IPC: G03C1/043
Filed: 1945-04-20
Abstract: 592,676. Photographic light-sensitive material. DU PONT DE NEMOURS & CO., E. I. April 20, 1945, No. 9946. Convention date, April 20, 1944. [Class 98 (ii)] Photographic material comprises a support and a light-sensitive silver halide emulsion layer with a water-permeable binder containing in the emulsion layer or in a separate layer (e.g. a substratum or supercoat gelatin or polyvinyl alcohol layer) coated adjacent thereto a wetting agent and a polyoxyalkylene ether of a hexitol ring dehydration product, or containing one in the emulsion layer and the other in the separate layer. The polyoxyalkylene ethers alter the induction period of development and result in increased density of the silver image, and render developable latent images not previously developable. The polyoxyalkylene ether may contain one or more groups R or RCO attached to a cyclic oxygen atom thereof, R being an aliphatic hydrocarbon radical containing at least 8 carbon atoms, and may be a polyoxyalkylene ether of a hexitan or hexide. The wetting agent may be saponin, and may be added to the emulsion after it has been brought to maximum sensitivity prior to coating. In example 1, speed, gamma and fog data are given for developed gelatino-silver iodobromide emulsion containing saponin and (a) mannitan monolaurate polyoxyalkylene ether, and sorbitan monolaurate, mono-oleate, and monostearate polyoxyalkylene ethers each containing 20 oxyalkylene groups divided in 3 chains. In example 2, contrast and fog data are given for developed silver chlorobromide emulsion containing saponin and sorbitan monolaurate polyoxyalkylene ether containing 20 oxyalkylene groups in 3 chains. Example 4 illustrates the effect of ageing at room temperature and at 120‹ F. between exposure and development. Mannitan and mannide mono-, di- and trioleates, stearates, palmitates and margarates containing from 8 to 18 or more carbon atoms distributed in 1 to 3 chains, mannide ether esters, and mannitan, mannide, sorbitan and sorbide decyl, dodecyl, tetradecyl, hexadecyl and octadecyl ethers containing oxyalkylene, especially oxyethylene, groups may also be used. The invention may be applied to silver chloride emulsions and to emulsions containing as binder agar-agar, polyglucuronic acid, zein, collodion, water-soluble cellulose derivatives (e.g. substantially hydrolysed cellulose acetate, cellulose esters of hydroxy monocarboxylic acids such as lactic and glycolic acids and alkali metal salts of cellulose esters of dicarboxylic acids such as phthalic acid), polyvinyl alcohol, partially hydrolysed polyvinyl acetate and interpolymers thereof with unsaturated compounds such as styrene and maleic acid, and water-soluble polyvinyl acetals. The emulsion may contain dye sensitizers and sulphur sensitizers such as allylthiourea, thiocyanates, sodium thiosulphate and sodium hyposulphite. Other wetting agents include alkali metal salts of alkylated naphthalene sulphonic acids and of long chain alkyl sulphates and sulphonates. Specifications 235,211, [Class 98 (ii)], 376,746, 443,559, [Group IV], 513,471, 519,895 and 537,961 are referred to.