Patent GB-562960-A (GB)
Title: Production of coloured photographic images
IPC: G03C7/38
Filed: 1942-11-25
Abstract: 562,960. Coloured photographic images. STAMMERS, D. W., and IMPERIAL CHEMICAL INDUSTRIES, Ltd. Nov. 25, 1942, No. 16705. [Class 98 (ii)] A dye image is produced either by developing a reducible silver salt with an aromatic amino developing agent in the presence of a colour coupler which is a 2 : 4-diarylpyrrole of formula wherein R<1> and R<11> stand for aryl radicals (e.g. of the benzene or naphthalene series) substituted or not and the same or different and R<111> stands for H or for a non-reactive substituent (e.g. an aryl-, alkyl-, alkylamino-, benzylideneamino-, or acylamino-radical), or by treating material comprising a hardened colloid image with an oxidation product of such a developing agent or with a p-nitrosodialkylaniline or with a diazonium salt in the presence of such colour-coupler, or by treating material containing such colour coupler with a diazonium salt to give a uniformly dyed material and producing the coloured image by the dyedestruction process. 2 : 4 - Diarylpyrroles specified.are 2: 4-diphenylpyrrole, 2-(p-methoxyphenyl) - 4 - phenylpyrrole, 2 - phenyl - 4 - (p - methoxyphenyl)-pyrrole; 2-(m-hydroxyphenyl)- 4 - phenylpyrrole, 2 - phenyl - 4 - (m - hydroxyphenyl)-pyrrole, 2-(o-chlorophenyl)-4-phenylpyrrole, 2 - phenyl - 4 - (o - chlorophenyl) - pyrrole, 2 - phenyl - 4 - (p - bromophenyl) - pyrrole, 2 - (p - acetylaminophenyl)-4-phenylpyrrole, 2-alpha-naphthyl-4-phenylpyrrole, 2-phenyl-4-(alpha-naphthyl)- pyrrole, 2-phenyl-4-#-naphthylpyrrole, 2 : 3 : 4- triphenylpyrrole, 3 - benzoylamino - 2 : 4 - diphenylpyrrole, 3-acetylamino-2 : 4-diphenylpyrrole, and 3-benzoylamino-2:4-di-p-tolylpyrrole, and the corresponding sulphonic acids and their salts. Aromatic amino developing agents specified are p-aminodimethylaniline, p - aminodiethylaniline, p - amino - di - n butyl - aniline, p methylaminoaniline, p -ethylaminoaniline, chloro - p - phenylenediamine, 1: 2 : 5- toluylenediamine, 2 - amino - 5 - diethylaminotoluene, N-p-aminophenylpiperidine, N-methyl: N-#-hydroxyethyl-p-phenylenediamine, N-nbutyl : N-#-hydroxyethyl-p-phenylenediamine, # : gamma - dihydroxypropyl - p - phenylenediamine, and N : N-diethyl-o-phenylenediamine. The couplers may be in the developing solution or in the emulsion. Slightly soluble couplers may be incorporated in developing solutions using water-miscible organic solvents, e.g. ethanol. Dyes formed from some of the couplers show improved transmission in the blue region. The couplers may be incorporated in bichromatesensitized colloid (e.g. gelatin, gum arabic, or albumen) layers and after exposure and washing out unexposed colloid with hot water, colour is produced in the exposed parts by treatment with a p-nitrosodialkylaniline or a derivative thereof. Materials containing the couplers may be treated with'diazonium salts to form azo dyes which are then locally destroyed by the dye-destruction process, e.g. as described in Specifications 133,034, [Class 98 (ii)], and 496,558, to form dye images. In example 1, a colour developer comprises as developing agent 2 amino - 5 - diethylaminotoluene hydrochloride and as coupler 2-phenyl-4-(m-hydroxyphenyl)- pyrrole. Developed silver may be removed by successive treatments with aqueous potassium ferricyanide and aqueous sodium thiosulphate. In example 2, the developer is the same, but the coupler is the sodium salt of 2-phenyl-4-(ochlorophenyl)-pyrrolemonosulphonic acid. In example 3, the coupler is the sodium salt of 2 - phenyl - 4 - (p methoxyphenyl) - pyrrolemono - sulphonic acid. In example 4, the developing agent is N : N-diethyl-p-phenylenediamine sulphate, and the coupler the ammonium salt of 2: 4-diphenylpyrrolemonosulphonic acid. In example 5, 2-phenyl-4-(2-chlorophenyl)-pyrrole is incorporated in the emulsion, and acetone is added to the developing solution. The addition of other 2 : 4-diarylpyrroles to the emulsion is described. Specifications 540,368, and 541,558, and 554,102, 556,156 and 562,753, [all in Group IV], also are referred to.