GB560253A - Improvements in the production of photographic silver images in blue-black tones using a methylol nitromethane - Google Patents

Abstract

560,253. Photographic silver images in blue - black tones. DU PONT DE NEMOURS & CO., E. I. July 6, 1942, No. 14752/43. Convention date, June 13, 1941. Divided out of 560,173. [Class 98 (ii)] Photographic silver images in blue-black tones are produced by developing' a photographic material containing a reducible silver salt image in the presence of a methylol nitromethane. The compound may be present in the material prior to exposure and development, e.g. in the emulsion, support (including the paper pulp or a size for the paper), substratum, antistatic, antiabrasion, baryta, backing, or protective layer, or may be incorporated in the developer. The compound may also be incorporated by bathing the material in a solution thereof prior to development. After incorporation of the compound, the material may be aged at from 65 to 140‹ F. with high humidity. The tone obtained varies with the halide ratio of the emulsion, the degree of hardness of the emulsion, the developer, the particular compound, and the sensitizing dye. Lesser quantities are needed if the material is aged. Compounds specified are monomethylol nitromethane, dimethylol nitromethane, and trimethylol nitromethane. In example 1, trimethylol nitromethane is added to a gelatino silver chlorobromide emulsion and the emulsion is coated on paper and kept at 130‹ F. for 8 hours. In example 2, trimethylol nitromethane is added to a gelatino silver halide emulsion, which is coated on a base, dried, and maintained at 120‹ F. for 14 hours.. In example 3, trimethylol nitromethane is added to a substratum solution, which is coated on a film support, followed by a fine-grain silver halide emulsion. The film is aged for 1 week at slightly elevated temperatures. Other emulsion binders, e.g. cellulose derivatives, regenerated cellulose, synthetic resins, agar-agar, albumens, and gums, may be used. The sensitizing dyes employed may be cyanine, carbocyanine, pseudocyanine, kryptocyanine, neocyanine, merocyanine, styryl, cyazine, or rhodanine dyes, including both salts and bases. Desensitizing agents, fog inhibitors, emulsion stabilizers, hardeners, and wetting agents (e.g. sodium higher alkyl sulphonates and sulphates, and saponine) may also be incorporated. The compounds are useful with kinematographic, lithographic, radiographic, camera, and stripping films and printing papers. The Specification as open to inspection under Sect. 91 refers also to the use of substituted monomethylol and dimethylol nitromethanes. This subject-matter does not appear in the Specification as accepted.