GB663457A - Hardening photographic gelatino silver halide film of improved photographic properties - Google Patents

Abstract

663,457. Photographic plates. GENERAL ANILINE & FILM CORPORATION. Nov. 8, 1949 [Dec. 16, 1948], No. 28615/49. Drawings to Specification. Class 98 (ii). Hardened gelatino silver halide emulsion layers having no after-hardening tendency and which swell uniformly , in a direction perpendicular to their support when brought into contact with processing solutions are made by incorporating 2,4-dihydroxybenzaldehyde with or without a polyhydroxybenzene such as resorcinol, phloroglucinol, methylphloroglucinol, pyrogallol or 1,2,4 - trihydroxybenzene, or mixtures thereof, into the emulsion; coating, using a support such as cellulose-acetate, - formate, -propionate, -butyrate, -acetate-propionate, -acetate-butyrate or -nitrate, polyvinyl chloride or copolymers of this with vinyl acetate or vinylidene chloride; and providing a low molecular weight organic hardening agent such as formaldehyde, paraformaldehyde, acetaldehyde, glyoxal, pyruvic aldehyde, nitromalonic aldehyde, mucochloric acid, or trimethylolmelamine in a further colloid layer or in the support itself so that this hardening agent may diffuse into the gelatino silver halide layer and effect or complete the hardening process. Trimethylolmelamine, itself film-forming, may be applied in aqueous solution without a separate colloid. The process avoids irregularities, in photographic quality, of the resulting hardened layers, which may result from adding all the hardeners to the emulsion melt in processes as of Specification 632,763. In Example I, formaldehyde is applied in gelatine solution, so as to constitute an overcoat layer lying upon an emulsion layer containing 2,4-dihydroxybenzaldehyde and resorcinol. Examples II and III apply, similarly, gelatine solutions of glyoxal and other aldehydes. All the examples show data comparing the emulsion layers before and after application of the additional aldehydes. Specification 604,378 also is referred to. The Specification as open to inspection under Sect. 91 comprises also the application of formaldehyde and similar hardening agents in solution or gaseous form, without a colloid, to emulsion layers of the type indicated above. This subject-matter does not appear in the Specification as accepted.