Patent GB-500793-A (GB)
Title: Process of and materials for colour photography
IPC: G03C7/26
Filed: 1937-05-10
Abstract: 500,793. Colour photography. KODAK, Ltd. May 10, 1937, No. 33290/38. Convention date, May 9, 1936. Divided out of 500,826. [Class 98 (ii)] Material having three differentially colour sensitized silver halide emulsion layers inseparably superimposed on a single support is characterized in that the middle emulsion layer is protected on both sides against the action of blue light by filter colouring matters which remain after ordinary development. or after development and removal of the silver or conversion of the silver to silver salt. The material may have a blue-violet sensitive upper emulsion layer a middle yellow and green sensitive layer, and a lower red or infra-red sensitive layer, or a top blue-violet sensitive layer, a middle red and orange sensitive layer, and a lower yellow and green sensitive layer, or a top red-sensitive layer, a middle yellow-green sensitive layer and a lower blue-sensitive layer. 4: 41-dichloro- 2 : 2<1> : 8-triethylthiacarbocyanine chloride sensitizes very strongly to the extreme orange red and the red but not to the yellow and green. A yellow filter may be arranged between the blue-sensitive layer and the middle yellow green or red-orange sensitive layer, or in the blue sensitive emulsion, or the material may be coloured yellow throughout. A green or redorange filter may be arranged, between the middle and lower layers. Strongly swelling gelatine is used for filter layers. The filters are stable to the developer and mild oxidizing agents but capable of removal by acids, bases, oxidation, or reduction. If the material contains a yellow filter layer or a yellow-dyed blue. sensitive silver halide emulsion layer, the remaining layers may be bathed in yellow, red or orange dye solutions after development. The red filter dye is water-insoluble or non- diffusing. Insoluble dyes are precipitated in the gelatine or added thereto in a highly dispersed state. Water-soluble dyes are added or precipitated in the form of insoluble salts. Water-soluble substantive dyes may be used. Colouring matters referred to are (a) insoluble colouring matters synthesisable in the gelatine, such as the a zine and phenylhydrazone of alloxan, anils of hydroxyaldehydes, alpha-naphthol azo dyes, benzene-azo-phenol and azo-phenol especially meta-substituted azo-compounds, all of which are soluble in sodium carbonate and alkali; (b) basic colouring matters such as auramine, thioflavine T, nitrosodimethylaniline, azomethines, anils, and azo-dyes with amino-groups in meta-position, all readily washed-out by dilute acids ; (c) splitting anils and arylated auramines, which may contain amino and dimethylamino groups, converted to soluble salts by a bisulphite or thiosulphate ; (d) azomethines, indophenols and indamines, split by dilute acids or converted to soluble salts by a bisulphite or thiosulphate ; (e) diazoamino compounds from o-p-substituted amines, split by acids ; (f) arylazohydroxy anilides, decomposed by acid ; (g) coloured ferrocyanides, such as titanium ferrocyanide, copper or uranyl ferrocyanide, and colourless ferrocyanides such as those of zinc, and thorium, serving as mordants for yellow and red basic dyes, split by sodium carbonate, caustic alkali, or ammonia and soluble in potassium oxalate or thiosulphate ; (h) zinc murexide, decolourized by acid ; (i) insoluble complex compounds split by dilute acids, such as lakes of alizarin dyes, and other hydroxy- and dihydroxyanthraquinones, complexes of titanic acid with phenols and phenolcarboxylic acids precipitated by aromatic bases, complex salts of copper, nickel and cobalt salts with hydroxy-guanidine, hydroxyanidine, biformamide, guanyl-formamide, guanyl-urea, nitroso-#-naphthol, complexes of zinc and cadmium with isonitrosoacetophenone, complexes of copper and nickel salts with #-naphthaldoxime, complexes of nickel with peonol, and complexes of magnesium, zinc, cadmium, beryllium, aluminium, titanium, thorium, uranyl, ferrous, and copper salts with o-hydroxyquinoline ; (j) azo-dyes split by reduction; (k) dyes destroyed by oxidation, such as triphenylmethane dyes, aminohydroxyanthraquinones and their sulphonic acid salts, substantive azo dyes and their insoluble or non-diffusing salts, fulgides, isocyanines and other quinoline dyes; (l) light-unstable dyes, such as isocyanines, fulgides and Beathorn's quinaldinic acid dyes, quickly destroyed by ultra-violet light. Triphenylmethane dyes may be left in the image in kinematograph films. In reversal, the material, after camera or printing exposure, is developed with a neutral black developer such as ferrous oxalate, amidol or diamido-ocresol or with other organic developers in solutions containing sodium carbonate. The material may be saturated in a strong solution of the developing agent and the development effected in solutions of sodium carbonate, ammonia, alkali bicarbonate, borax or trisodium phosphate, or a concentrated developing solution is allowed to diffuse into all the layers at a low temperature and development effected by warming. The residual silver halide may be used directly for reversal development or may be first converted to highly dispersed silver chloride. The lower and upper layers are successively exposed with blue light and developed blue-green and yellow respectively. The upper layer may first be treated with a silver solvent. The middle layer which may be of silver chloride is colour developed without exposure with an ammoniacal, alkaline, alcoholic, or acetonic colour developer, preferably in the absence of air. Alcoholic or acetonic alkaline leucovat dye solutions may also be used. Residues of latent images in the other layers may previously be destroyed by a mixture of potassium ferricyanide and ammonia In a modification, all the developed silver is removed, the filter dyes destroyed, and the middle layer exposed to white, blue, or ultra-violet light or to soft X rays and developed purple, silver being finally removed. Only one outer layer may be processed before the middle layer if the other filter is not removed. The middle layer may be rendered developable immediately after developing of the outer layers by exposure from above or both sides to ultraviolet light or soft X-rays. The residual silver bromide of the middle layer may be converted into silver iodide or a complex salt thereof and coloured purple or blue-green by mordanting dyes made insoluble before removal of the mordanting agent by phosphotungstates. If the yellow-green sensitizer of the middle layer' and the filters are stable to development and oxidation, the silver is removed after the first development, the middle layer is exposed from below, above, or both sides to yellow light and developed purple, and the other layers are successively re-exposed and colour developed. Yellow-green light may be used for re-exposure of the middle layer, blue for the outer layers. If both sensitizers are stable to development, the lower layer is re-exposed with red light and coloured bluegreen, the middle layer re-exposed from above with yellow light and developed purple, and the upper layer exposed to blue light and developed yellow. In the redevelopment process, the material is dveloped black, fixed, and bleached to silver chloride or silver bromide. The outer layers are successively exposed to blue light and colour developed, the middle emulsion rendered developable by thiourea or other fogging agent and colour developed, or colour developed without exposure by a vigorous colour developer, the silver removed, and the filter dyes destroyed or washed out. If yellow-green sensitizers such as erythrosine, rhodamine B and GG, the dyes " 777," " 666 " and " 555 " of U.S.A. Specification 1,897,866 or other pseudocyanines and pinacyanols. difficult to wash out and stable to mild oxidizers are used for the middle layer, the latter may be re-exposed with yellow-green light and colour developed, and the outer layers reexposed with blue light. After colour development of the outer emulsions, the reduced silver may be removed and the middle layer reexposed after removal of the filters. Only one outer layer may be colour developed before processing of the middle layer if the other layer is left intact. The material may be used for making prints from three colour separation negatives or diapositives or bipack, multicolour screen material, and lenticular screen material, particularly lenticular screen bipack material. Specifications 376,746, 498,875, 500,716, 500,720, 500,795, 500,796, 500,826, and 501,003 are referred to. The Specification as open to inspection under Sect. 91 comprises also the use of development stable infra-red sensitizers such as kryptocyanine and neocyanine. Ultra-filter layers may be used or the whole material may be treated with an ultra-violet absorbing solution. Acid filter dyes may be precipitated with inorganic bases or organic bases such as the basic dyes auramine, acridine yellow, benzoflavine or thioflavine. Basic filter dyes may be precipitated by high molecular weight sulphonic acids such as diazo light yellow 2G, di-(p-aminobenzoyl)-alpha-naphthylamine sulphonic acid or anthraquinone sulphonic acid or by complex inorganic acids such as phosphotungstic, silicotungstic, or phosphomolybdic acids or their salts. Ultra-violet absorbers are aesculine, quinine, anethol, triphenylmethane, cumarone, acetaminoquinoline, hydroxyquinoline sulphonic acids, hydroxynaphthoic acids, naphtholsulphonic acids, naphthylaminosulphonic acid and anthracene substitution products, and also insoluble salts, esters, anilides and other derivatives of the above compounds. Materials with the lower filter layer constituted by an ultra-violet absorbing layer, with two ultra-violet absorbing layers, the upper of which may be coloured yellow with nitrosodimethylaniline, and with an upper ultra-violet absorbing layer and a lower orange red filter layer