Patent GB-1320797-A (GB)
Title: Supersensitized photographic silver halide emulsions spetrally  sensitized with tricarbocyanine dyes
IPC: G03C1/12
Filed: 1970-09-23
Abstract: 1320797 Supersensitized photographic silver halide emulsions EASTMAN KODAK CO 23 Sept 1970 [23 Sept 1969 28 May 1970] 45301/70 Heading G2C A photographic silver halide emulsion contains (1) at least one spectrally sensitizing tricarbocyanine dye in which the meso carbon atom of the methine linkage of the dye is attached to the N atom of an amino group forming an enamine with the methine linkage of the dye in supersensitizing combination with (2) a sulphonated polycarbocyclic aromatic organic supersensitizer and/or a silver halide reducing agent. The polycarbocyclic aromatic organic supersensitizer is a compound containing a polycarbocylic aromatic group i. e. two or more benzene rings fused together, or at least two benzene rings or other aromatic carbocyclic nuclei directly joined together or joined together through an aliphatic linkage (see Specifications 895930 and 893681). Component (2) may also comprise an azaindene. The tricarbocyanine dye may have the formula: - wherein n and m are 1 or 2; R<SP>1</SP> and R<SP>2</SP> are each alkyl, substituted alkyl, cycloalkyl, aryl, substituted aryl; X<SP>-</SP> is an acid anion which may be included in R<SP>1</SP> or R<SP>2</SP>; Z<SP>1</SP> and Z<SP>2</SP> each completes a non-metallic heterocyclic nucleus having 5 or 6 atoms in the heterocyclic ring; Q is an optionally substituted divalent linkage; R<SP>3</SP> and R<SP>4</SP> are each alkyl, substituted alkyl, aryl, substituted aryl, or together may complete a non-metallic heterocyclic nucleus having 5 or 6 atoms in the heterocyclic ring. The azaindene may be a hydrozy or amino substituted tri-azaindene, tetra-azaindene or penta azaindene. The silver halide reducing agent may be a dihydroxy-arene e.g. hydroquinone, or a dihydroxy substituted gamma-lactone, e.g. ascorbic acid, tetronimide, pyronimide, furan or pyrrole. The polycarbocyclic aromatic organic supersensitizer may be a bis[s-triazin -2-ylamino] stilbene -2, 2'-disulphonic acid sodium salt, 4, 4'-bis[(4-amino-6-anilino-striazin -2-yl) amino] -2, 2'-stilbene disulphonic acid disodium salt, 4, 4'-bis-[(4-amino -6- phenoxy -5-triazin -2-yl) amino]-2, 2'-stilbene disulphonic acid disodium salt, 4, 4'-bis (3- phenylureido)-2, 2'-stilbene disulphonic acid disodium salt, 4, 4'-bis [4, 6- bis(p-sulphoanilino) -s-triazin -2- ylamino]-2, 2'- stilbene disulphonic acid hexasodium salt, 4, 4'-bis [(4- anilino -6-hydroxy -striazin-2-yl)amino]-2,2'- stilbene disulphonic acid disodium salt, 4, 4'-bis [(4-hydroxy -6-phenoxy -s-triazin-2-yl)- amino]- 2, 2'-stilbene disulphonic acid disodium salt, 4, 4'-bis[(4, 6-bisanilino -s-triazin -2-yl) amino]- 2, .2'-stilbene disulphonic acid disodium salt, 4, 4'-bis [2-phenoxy -4- (2- hydroxyethylamino) -1, 3, 5-triazin-6- ylamino] stilbene -2, 2'- disulphonic acid disodium salt, 3, 7-bis (4- methoxy -3-sulphobenzamido)- dibenzoltriophenedioxide sodium salt or chrysene -6- sulphonic acid sodium salt. The emulsion has high sensitivity to long wavelength infrared radiation as well as blue radiation, is stable on storage and has a low fog level.