| 摘要 |
699,888. Photographic silver images. DU PONT DE NEMOURS & CO., E. I. Jan 25, 1952 [Jan. 26, 1951], No. 2117/52. Class 98 (ii). The colour of developed photographic silver images is modified by incorporating in the photographic silver halide emulsion or applying thereto at some stage in its preparation of processing to produce a fixed and dry photographic record, a small quantity of a salt of a mercapto-azole with an N-hydrocarbon (preferably N-aryl) substituted biguanide. The salt may be incorporated in a colloid (e.g. gelatin) sub-coating or super-coating layer, in the developer, or in a solution applied to the processed layer, which may or may not have been dried, and which is then hot-dried. The mercapto-azole may be 2-mercaptobenzthiazole, 2-mereaptobenzoxazole, or 5-mercaptotetrazole or an alkyl or aryl derivative thereof. In example 1, the effect of the addition of phenylbiguanide-2-mereaptobenzthiazole salt to a silver chlorobromide emulsion is compared with a similar control emulsion and with a similar emulsion containing 2-mercaptobenzthiazole as regards warmth of image colour, stabilization of image colour on hot drying, and emulsion sensitivity. In example 2, a similar comparison is made between the effect of gelatin supercoats containing phenylbiguanide- 1-phenyl-5-mercaptotetrazole salt and containing 1 - phenyl - 5 - mercaptotetrazole and of a plain gelatin supercoat. In example 3, a print is treated with an aqueous solution of phenylbiguanide - 2 - mercaptobenzthiazole salt and hot dried. In examples 4, 5 and 7, o-tolylbiguanide salts of 1-phenyl-5-mercaptotetrazole, 2-mercaptobenzthiazole, and 2-mercaptobenzoxazole, phenylbiguanide salts of 1- phenyl - 5 - mercaptotetrazole, 2 - mercaptobenzoxazole, and 2 : 5 - dimercapto 1 : 3 : 4 - thiadiazole, and diphenylbiguanide salts of 2 : 5 : dimercapto - 1 : 3 : 4 - thiadiazole and 1 - phenyl-5-mercaptotetrazole are added to silver chlorobromide emulsions. In example 6, processed prints are treated with aqueous solutions of o-tolylbiguanide 1-phenyl-5-mercaptotetrazole, 2 - mercaptobenzthiazole, and 2 - mer - captobenzoxazole salts and phenylbiguanide 1- phenyl - 5 - mercaptotetrazole and 2 - mer - captobenzoxazole salts. Other salts, e.g. of 1-α- naphthyl - 5 - mercaptotetrazole, 5 - mercapto - 1: 3 :4-triazole, thiobarbituric acid, mercapto- - thiadiazole, and mercaptopyrimidines, may be used. The emulsions may contain sensitizing - dyes, or antifogging, hardening, wetting, or matting agents, and may have as binder gelatin, agar-agar, polyglucuronic acid, zein, collodion, part-hydrolysed cellulose acetate, cellulose esters of lactic or glycolic acids, alkali metal salts of cellulose esters of dicarboxylic acids (e.g. phthalic acid), polyvinyl alcohol, partially hydrolysed polyvinyl acetate and interpolymers thereof with styrene or maleic acid, or a watersoluble polyvinyl acetal. Specification 527,283 is referred to.
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