| 摘要 |
693,632. Processing photographic materials. KODAK, Ltd. June 1, 1950 [June 1, 1949], No. 13762/50. Addition to 631,184. Class 98 (ii). A rapid process for the formation of an image in a photographic emulsion layer comprises exposing imagewise a silver halide emulsion layer containing a developing agent, developing a silver image therein by treatment with an alkaline solution, stabilizing the layer by treatment with a solution of an alkali metal or ammonium thiocyanate or thiosulphate or of a thiourea or thioglycollic acid, and drying without further treatment. The developing agent is preferably a water-insoluble compound, e.g. 2: 3-, 2: 5-, or 3: 4-dihydroxydiphenyl or 5:6:7:8 - tetrahydronaphthohydroquinone, or may be water-soluble such as hydroquinone, pyrocatechol, or p -methylaminophenol sulphate. The emulsion should be well-hardened. The emulsion binder may be gelatine, polyvinyl alcohol, partially hydrolised polyvinyl ester, or cellulose ester. The stabilizing bath is preferably acid to neutralize the alkali of the developing solution. The alkaline solution may be applied by wiping the surface of the emulsion with a sponge, rubber roll, or other applicator wet with such solution, or the exposed layer may be pressed against a pad moistened with the alkaline solution. In example (1), aqueous solutions of silver nitrate and of sodium chloride are simultaneously run into aqueous gelatine solution while stirring, aqueous gelatine solution, methanol 3: 4-dihydroxyphenyl solution, and formaldehyde or other hardener are successively added, and the emulsion is coated on paper. After exposure, the material is treated in an aqueous solution of sodium carbonate, hydroxide, and thiosulphate, and potassium bromide to effect development, either by applying such solution by a sponge or by moistening a pad of cloth, paper, felt, sponge rubber, or water-permeable hydrophilic colloid (e.g. gelatin, gum arabic, or polyvinyl alcohol hardened with melamine-formaldehyde condensation product) and pressing the exposed layer thereagainst, and is similarly treated with an aqueous stabilizing solution of sodium sulphite, bisulphite, and thiosulphate. In example (2), aqueous silver nitrate and potassium bromide solutions are successively run into a gelatine solution, further gelatine solution and a surface-active agent are added, the pH is adjusted to 5.0, a methanol solution of 3: 4- dihydroxydiphenyl and formaldehyde are successively added, and the emulsion is coated on paper. The further procedure is as in example (1). The emulsion may also be a direct-positive type of emulsion such as is described in Specification 667,206.
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