| 摘要 |
1,228,868. High contrast photographic silver halide materials. EASTMAN KODAK CO. Aug. 15, 1968 [Aug.18, 1967], No.39109/68. Heading G2C. A photographic material comprises a support bearing a layer of a high contrast silver halide emulsion (defined as one in which the halide comprises at least 50 mole per cent chloride and less than 5 mole per cent iodide, the remainder being bromide, said emulsion when exposed on a sensitometer and developed for 2 minutes at 20‹C. in the developer whose composition is: sodium sulphite (anhydrous) 30 g., paraformaldehyde 7À5 g., potassium metabisulphite 2À6 g., boric acid (crystalline) 7À5 g., hydroquinone 22À5 g., potassium bromide 1À6 g., and water to make 1000 ml., has a gamma of at least 4 measured between a density of 0À3 and 3À0) containing dispersed therein a waterinsoluble vinylpolymer, the halide of which emulsion comprising at least 85 mole per cent chloride, 0À1 to 5À0 mole per cent iodide and the balance bromide. In the examples the use of copoly (methylacrylatesulphopropyl acrytate) and copoly (methylacrylatesulphopropyl acrylate -2-acetoacetoxy-ethyl methacrylate) is disclosed. The silver halide emulsion, used in the examples, according to the present invention contains 90 mole per cent chloride, 9 mole per cent bromide and 1 mole per cent iodide. The examples also disclose other silver halide emulsions by way of comparison. A method of processing a high contrast photographic material as defined above comprises inserting the imagewise exposed material into a continuous transport processing machine in which the developer solution is one capable of infectious development. The developer solution may contain a carbonyl bisulphite-amine condensation product and may also contain a dihydroxybenzene developing agent. The developer preferably contains 0À05 to 0À5 mole per litre of the developing agent and 0À10 to 1À0 mole per litre of the condensation product. In the examples sodium bis-(2-hydroxyethyl) aminomethane sulphonate is the condensation product and hydroquinone is used as the developing agent. |
