Patent GB-560173-A (GB)
Title: Improvements in the production of photographic silver images in blue-black tones
IPC: G03C1/35
Filed: 1942-07-06
Abstract: Photographic silver images in blue-black tones are produced by developing a photographic material containing a reducible silver salt image in the presence of an organic compound containing at least one methylol or lower alkoxy-methyl group directly attached to an amide nitrogen atom.  (The " lower alkoxy " group contains from 1 to 5 carbon atoms.)  The compound may be present in the material prior to exposure and development, e.g. in the emulsion support (including the paper pulp or a size for the paper), substratum, antistatic, antiabrasion, baryta coating, backing, or protective layer, or may be incorporated in the developer.  The compound may also be incorporated by bathing the material in a solution thereof prior to development. After incorporation of the compound, the material may be aged at from 65-140 DEG  F. with high humidity.  The compounds are preferably open chain methylol amides and lower alkoxymethyl amides, wherein the alkoxy group contains 1 to 5 carbon atoms and the methylol or alkoxymethyl radical or radicals are attached directly to an amide nitrogen atom.  The compounds may be symmetrical and unsymmetrical methylolureas, e.g. compounds of formula NRR1-CO-NR11R111, at least one of R, R1, R11 and R111 being a methylol radical and the others the same or different and hydrogen atoms, hydrocarbon groups, or methylol groups.  Specific compounds are monomethylolurea, symm - dimethylolurea, symm - dimethylmonomethylolurea, cyclic dimethylol diurea, N : N1-bis - (methoxymethyl) - urea, N - methylol - N : N1-bis-(methoxymethyl)-uron, methylol - formamide, dimethylol - formamide, methylol - acetamide, dimethylol - adipamide, N : N1 - bis - (methoxy - methyl) - adipamide, methylol - phthalimide, N : N1 - bis - (methoxymethyl)-oxamide, N : N1 - bis - (methoxymethyl)-fumaramide, N : N1-bis-(methoxymethyl)-succinamide, N : N1-bis-(methoxymethyl) - sebacamide, dimethylol - melamine, trimethylol-melamine, N : N1 : N11-tris-(methoxymethyl)-melamine, N : N1 : N11-tris-(ethoxymethyl)-melamine, tetrahydro - 1 : 3 - bis - (methoxymethyl) - 5 - methyl - 2(1) - s - triazone, tetrahydro - 1 : 3 - bis - (methoxymethyl) - 5 - b -hydroxyethyl - 2(1) - s - triazone, and N-methylol - N - butyl - urethane.  The tone obtained varies with the halide ratio of the emulsion, the degree of hardness of the emulsion, the developer, the particular compound, and the sensitizing dye.  Suitable concentrations of the compounds in various modes of use are given.  Lesser quantities are needed if the material is aged.  In example 1, monomethylolurea is added to a silver iodobromide emulsion.  In example 2, trimethylol-melamine is added to a silver iodobromide emulsion which is dried at 110 DEG  F. for 20 hours and then rehumidified at 80 per cent humidity.  In example 3, symm-dimethylol-urea is added to a silver iodochloride emulsion sensitized with 9-ethyl-3 : 31-dimethyl-2 : 51-benzoxyrhodanine merocyanine, and the emulsion coated on a cellulose acetate support and aged.  In example 4, chloro-bromide paper is bathed in an aqueous solution of symm.-dimethylol-urea.  In example 5, an anti-abrasion layer containing gelatin and dimethylol-formamide is applied to a silver halide emulsion on a film support.  In example 6, material caryying a silver halide emulsion layer is bathed in a methyl alcohol-water solution of symm.-dimethylol-urea.  In example 7, tetrahydro-1 : 3-bis-(methoxymethyl)-5-b -hydroxyethyl-2(1)-s-triazone is added to a silver iodobromide emulsion, which is then aged.  In example 8, a solution of N : N1-bis-(methoxymethyl)-urea is added to a silver iodobromide emulsion which is then coated on a support and aged.  Other emulsion binders, e.g. cellulose derivatives, regenerated cellulose, synthetic resins, agar-agar, albumens, and gums, may be used.  The sensitizing dyes employed may be cyanine, carbocyanine, pseudocyanine, eryptocyanine, neocyanine, merocyanine, styryl, cyazine, or rhodanine dyes, including both salts and bases.  Desensitizing agents, fog-inhibitors, emulsion stabilizers, hardeners, and wetting agents, (e.g. sodium higher alkyl sulphonates and sulphates, and saponine) may also be incorporated.  The compounds have a hardening effect on emulsions.  The compounds are useful with kinematographic, lithographic, radiographic camera, and stripping films and printing papers.  Specification 544,728, [Group XX], is referred to. Dimethylol-melamine is prepared by reacting melamine in aqueous alkaline medium with two mols. of formaldehyde.  Trimethylol-melamine is similarly prepared using three mols. of formaldehyde.  N : N1 : N11-Tris-(methoxymethyl)-melamine is obtained by treating trimethylol and melanine in anhydrous methyl alcohol with dry HCL.  N : N1 : N11-Tris - (ethoxymethyl)-melamine is similarly prepared using anhydrous ethyl alcohol.  Dimethylolformamide is prepared by reacting one mol of formamide with two mols. of formaldehyde.  The Specification as open to inspection under Sect. 91 includes also the subject-matter of Specification 560,253 [Group XX].  This subject-matter does not appear in the Specification as accepted.