Patent GB-431142-A (GB)
Title: Improved process of modifying the sensitivity of photographic emulsions
IPC: G03C1/18
Filed: 1933-12-23
Abstract: 431,142. Sensitizing photographic emulsions. KENDALL, J. D., 23, Roden Street, Ilford, Essex. Dec. 23, 1933, No. 36248. [Class 98 (ii)] The sensitivity of a photographic emulsion is modified by treating it with a carbocyanine dye comprising two heterocyclic nuclei, each containing at least one nitrogen atom, linked together by a trimethine chain which itself forms part of a five-membered carbocyclic ring system. The following general formula is assigned the dyes wherein D stands for the residue of a five or six-membered heterocyclic ring system, R1, R2, R3 each stand for hydrogen or the hydrocarbon groupings of a cyclopentadiene homologue, or R1and R may be part of an arylene residue as in indene, A stands for an aryl, alkyl or aralkyl group and X for an acidic radicle. The production of such dyes is disclosed in Specification 431,187. One or more of such compounds is incorporated with the emulsion prior to casting or the finished emulsion may be immersed in a solution containing one or more of the compounds or both methods may be employed. The quantities of dyes suitable range from 0À03-0À35 grammes per 200 ozs. of emulsion and the strength of the sensitizing baths may vary from 1 in 5000 to 1 in 500,000. The sensitizing data of the following dyes are given :-2.2<1>-dimethyl-7.7<1>- dimethenyl-thiocarbocyanine bromide, 2.2<1>- diethyl- 7.7<1>-dimethenyl-thiocarbocyanine iodide 1.1<1> - dimethyl - 9.9<1> - dimethenyl - 2.2<1> - carbocyanine iodide and bromide, 2.2'-dimethyl- 4.5 : 4<1>.5<1> - tetroxydimethylene - 7.7'-dimethenyl-thiocarbocyanine iodide, 2.2<1>-diethyl- 4.5: 4<1>.5<1> - tetroxydimethylene - 7.7' - dimethenyl-thiocarbocyanine - p - toluene sulphonate, 2.2<1> - dimethyl - (and-diethyl-) -4.5.- 4<1>.5<1> - tetramethoxy - 7.7<1> - dimethenyl-thiocarbocyanine - p - toluenesulphonate, 2.2<1>- dimethyl - (and-diethyl-) - 4.4<1> - dimethylmercapto - 5.5<1> - dimethenylthio - 2.3 - diazolocarbocyanine bromide, 2.2<1> dimethyl- 3.4.3<1>.4<1> - dibenz - 7.71 - dimethenyl-thiocarbocyanine - p - toluenesulphonate, 1.1<1> - dimethyl- 9.9<1> - o - phenylene - 2.2<1> - carbocyanine - p - toluenesulphonate, 2.2<1> - dimethyl -(anddiethyl-) - 7.7<1> - o - phenylenethiocarbocyanine iodide, 2.2<1> - dimethyl - (and-diethyl-) - 4.5 :- 4<1>.5<1> - tetroxydimethylene - 7.7<1> - o - phenylenethiocarbocyanine - p - toluenesulphonate, 2.2<1> - dimethyl (and-diethyl-) - 4.5: 4<1>.5<1>- tetramethoxy - 7.7 - o - phenylene-thiocarbocyanine bromide, 2.2<1> - dimethyl (and-diethyl-)- 4.41 - dimethyhnercapto - 5.5<1> - o - phenylenethio - 2.3 - diazolocarbocyanine bromide, 2.2<1> - dimethyl - 3.3<1> - dimethylmercapto - 5,5' - o - phenylenethio - 2.4 - diazolocarbocyanine bromide, 1.1<1> - dimethyl - 9.9<1> - o - phenylene - 4.4<1> - quinazocarbocyanine - p - toluenesulphonate and the corresponding diethyliodide compound, 2.2<1> - dimethyl - 3.4 :- 3<1>.4<1> - dibenz - 7.7<1> - o - phenylenethiocarbocyanine iodide, 1.1<1> - or 3.3<1> - dimethyl - 2.2<1>- dimethylmercapto - o - phenylene- 4.4<1> - pyrimidocarbocyanine - p - - toluenesulphonate and the corresponding diethyl bromide, 1.1<1>- dimethyl - 7.7<1> - o - phenylene - 2.2<1> - pyridocarbocyanine iodide, 2.2<1> - dimethyl - 7.7<1> - o - phenylenethiocarbocyanine iodide and 1.1'- diethyl - 9.9<1> - o - phenylenecarbocyanine p - toluenesulphonate. Specification 431,141 also is referred to.