| 摘要 |
705,842. Photosensitive materials. KALLE & CO., AKT.-GES. Feb. 19, 1951, No. 4025/51. Class 98(2) Silver halide together with a water-soluble salt of a diazido compound having symmetrically arranged azido groups in a hardenable colloid such as fish glue, gelatine, polyvinyl pyrrolidone or polyvinyl alcohol is used as light sensitive layer on a base such as tracing cloth or paper, or cellulose acetate foil to constitute an intermediate reproduction material from which prints can be made, or on a base of metal to constitute a replacement of chromate-glue layers as used in lithography, the claims being restricted to the use of a ratio of diazido salt to colloid of not less than 1:4 and to the presence of not more than 1 per cent of alkali metal halides in the layer, restrictions necessary for satisfactory results. Exposure is under a negative and development with an alkaline metal-hydroquinone solution unexposed parts of the layer being washed off with cold or warm water before or after development to leave a black silver image in tanned colloid. Examples describe precipitation of stoichiometric proportions of silver nitrate and potassium chloride into a solution of glue, addition of 4 : 41 - diazidostilbene - 2 : 21 - disulphonic acid sodium salt or of the corresponding dicarboxylic acid, coating of this emulsion (without chilling and washing), exposure and development as indicated above. Specifications 401,898 and 452,745 are referred to.
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