GB657374A - Lumazines and alloxazines as catalysts in dye bleach baths for color photography - Google Patents

Abstract

657,374. Coloured photographic images. GENERAL ANILINE & FILM CORPORATION. Feb. 16, 1949, No. 4278. Convention date, March 27, 1948. [Class 98 (ii)] A coloured photographic image is produced in a photographic layer containing a developed silver image and a bleachable azo dye by selectively bleaching the dye in a bath containing a dye-destroying agent and, as an accelerating agent, a small quantity of a compound of one of the general formulµ wherein R and R 1 represent H or an alkyl or aryl group, R 2 and R 3 represent H or a methyl group, R 2 always being H when R 3 is methyl and vice versa, and Z represents the atoms necessary to complete an aromatic or heterocyclic ring or a polycyclic derivative thereof. Compounds specified include alloxazine, 7- (or 8-) - methylalloxazine, 7 : 8 : 9 - trimethylalloxazine, 7: 8 - tetramethylenealloxazine, 6: 7- (or 8: 9-)-benzoalloxazine, azaalloxazine, 7- aminoalloxazine, 7- (or 8-) sulphanilamidoalloxazine, lumazine, 6:7-dimethyl-lumazine, phenanthrolumazine, and 6:7 - diphenyllumazine. The dye destroying agent may be hydrochloric, hydrobromic, hydriodic, or phosphoric acid with or without an alkali or ammonium halide, e.g. sodium or potassium bromide or iodide, or sodium or ammonium chloride. In example (1), multilayer material is prepared from a gelatino silver iodobromide emulsion containing saponin and diphenyl biguanide hydrochloride, Direct Sky Blue being added to the red-sensitized emulsion, Fast Acid Magenta being added to the green-sensitized emulsion, and Dianil Yellow 2R and additional diphenyl biguanide hydrochloride being added to the non- colour - sensitized emulsion, and a yellow colloidal silver filter layer is provided between the green- and non-colour-sensitized emulsions. The support is cellulose acetate film or barytacoated paper. The exposed material is developed in a black-and-white developer, treated in an aqueous sodium acetate-acetic acid stop bath, fixed in a bath containing hypo, sodium sulphite, acetic acid, and potassium alum, and strips are bleached in baths containing (a) hydrochloric acid; (b) hydrochloric acid and riboflavin; (c) hydrochloric acid and potassium bromide; and (d) hydrochloric acid, potassium bromide, and alloxazine. In example (2), the procedure is similar, using lumazine. In example 3, an exposed and developed silver halide emulsion containing Diamine Pure Blue FF is treated in a dye destruction bath containing, hydrobromic acid and 7: 8-dimethyl alloxazine. Specification 651,124 is referred to. The Specification as open to inspection under Sect. 91 refers also to the use as an accelerating agent of 7- (or 8-) methyltetrahydroalloxazine. This subject-matter does not appear in the Specification as accepted.