GB506224A - Improvements in and relating to colour forming developers and processes of colour development - Google Patents

Abstract

506,224. Colour -photography. CEVAERT PHOTO-PRODUCTEN N.V., MERCKX, P. L. J. R., and KORBER, W. K. A. May 23, 1838. No. 15383. [Class 98 (ii)] A colour forming developer comprises an aromatic amino developing agent and a colour former consisting of a derivative of diphenylmethane or phenyhiaphthyhnethane having the general formula X-CH2-X<1>, where X is a phenyl residue with one hydroxyl group in ortho or para position to CH2 and in which at least two of the remaining hydrogen atoms in the nucleus are replaced by halogens (chlorine or bromine) and where X' is a phenyl or naphthyl residue with one hydroxyl-group in the ortho or para position to CH2 and in which the remaining hydrogen atoms of the phenyl or naphthyl residue can be substituted or not by halogens, alkyl, aryl, aralkyl, alkoxy, amino, or nitro groups and in which, in the case of a phenyl residue or the ring of a naphfhyl residue, which ring already contains an OH- group in the para position to the CH<2>, one or more of the remaining hydrogen atoms may be replaced by the corresponding number of hydroxyl groups. Blue or blue-green colours are produced. Examples of colour formers are 4-(2<1>-hydroxy-3<1> : 5<1>-dibrombenzyl)-6-brom-2- methylphenol, 4 - (2<1> - hydroxy - 3<1> : 5<1>- dibrom- .benzyl) -alpha - naphthol, 4 - (4' - hydroxy - 3<1> : 5<1>- dibrombenzyl)-m-cresol, 4-(2<1>-hydroxy-3<1> : 5<1>- dibrombenzyl) - 3 - methyl - 6 - isopropylphenol, 4-(2<1>-hydroxy-3 : 5<1>-dibrombenzyl)-3-methyl-6- bromphenol, 4 - (2<1> - hydroxy - 3<1> : 5<1> - dibrombenzyl) - 1 : 3 - dihydroxybenzene, and 4 - (2<1>- hydroxy - 3<1>: 5<1> - dibrombenzyl) - 2 - methoxyphenol. The aromatic amino developing agents include mono-, di-, and tri-amino aryl compounds, for example aminophenols and aminocresols and their halogen derivatives, aminonaphthols, and aromatic ortho and , para diamines such as p-phenylenediamine and derivatives substituted in the amino group or in the ring or in both, for example diethyl-pphenylenediamine; monoethyl - p - phenylenediamine, dimethyl-p-phenylenediamine, and 3- amino - 6 - dimethylaminotoluene. The hydrochlorides or-sulphates of these compounds may be used. The colour formers may be in the developing solution, and may be dissolved in organic solvents such as acetone, or may be added to the emulsion before or after coating. Developirig formulµ are given. The material may comprise plates, films or paper coated with gelatine or other silver halide emulsion, and the emulsions may be coated on one or both sides of the support. The developed silver may be removed by a bath containing potassium ferricyanide and sodium thiosulphate.