Patent GB-503822-A (GB)
Title: Process of colour photography
IPC: G03C7/30
Filed: 1937-07-07
Abstract: 503,822. Colour photography. KODAK, Ltd. July 7, 1937, No. 6660/39. Convention date, July 7, 1936. Divided out of 503,752 and addition to 498,663. [Class 98 (ii)] The process described in Specification 498,663 is applied to material comprising three differentially colour-sensitized silver halide emulsions inseparably coated in a single support some or all of the emulsions containing components coupling with the oxidation products of a developing agent formed by development of a silver salt image with an alkaline colour developer containing the developing agent and the coupling components being insoluble in water or aqueous sodium carbonate solution. The coupling components are not more soluble than the most soluble of the following, viz., tri-alpha-naphthol-triazine, alpha-naphthol-2-carboxylic acid-alpha-(or-#)-naphthytamide, alpha-naphthol-4-benzoyl-ketone, and the hydrazone of the last-named. The emulsions may contain such coupling components that each gives the appropriate colour with the same developing agent. The material may be processed directly after exposure or may be developed, fixed, and bleached, or may be processed by reversal. The material may comprise a top blue-violet sensitive emulsion layer, a middle yellow and green sensitive emulsion layer, and a bottom red or infra-red sensitive emulsion layer, or a top blue-violet sensitive layer, a middle red and orange or infra-red sensitive layer and a bottom yellow and green sensitive layer, or a top redsensitive layer which may contain desensitizers for blue, a middle yellow-green sensitive layer, and a bottom blue-sensitive layer. A yellow filter may be arranged between the blue-sensitive and the middle layers or in the blue-sensitive layer and a green or orange-red filter between the middle and bottom layers or in the middle layer. A colourless layer or yellow filter layer may be arranged between the middle and the bottom layers. The blue-sensitive emulsion may be on the opposite side of the support to the other two emulsion layers. Strongly swelling gelatine is used for the filter and emulsion layers. The bottom emulsion may be a highly colour-sensitized collodion emulsion coated on a thin film of cellulose acetate or regenerated cellulose or a hardened gelatine emulsion in which part of the gelatine is replaced by agar-agar, polyvinyl alcohol, or other less swelling colloids. The silver bromide, entirely or partially freed from gelatine by centrifuging, may be sensitized before mixing with the main part of the binder. The material may comprise alternatively an upper blue-sensitive silver bromide or chloride emulsion and a lower layer comprising a mixture of red and orange sensitized with yellow and green sensitized silver halide emulsion particles. A yellow filter layer may be between the two emulsion layers. A yellow-green sensitized and red-sensitized emulsions may be mixed, or the two emulsions may be pulverized or emulsified in an immiscible liquid such as tetrahydronaphthalene or xylene and the particles obtained thereby re-emulsified after weak tanning in solutions of gelatine, collodion or other. developer-permeable colloids. One or both of the emulsions may be collodion emulsions. One emulsion which may be a collodion emulsion, may be pulverized and re-emulsified in the other which may be a gelatine emulsion, of the particles are re-emulsified in collodion, the mixed emulsion layer is coated with gelatine, dextrine, or gum arabic. The mixed emulsion layer may be the upper layer, the film being exposed from the rear. One of the mixed emulsions may be a silver chloride gelatine or collodion emulsion. If the layers are on opposite sides of the support, the blue-sensitive layer can consist of silver chloride. Both emulsion layers may be collodion emulsions, and both may be coated with a gelatine, dextrine, gum arabic or other water-soluble colloid layer, the rear layer serving as an anti-halation layer. The developer may contain a large quantity of alcohol, and - alcohol, sodium carbonate, or sodium sulphate may be added to the various baths. The bottom layer of a three-layer plate and the middle emulsion layer of a film wherein the three emulsion layers are distributed between the two sides of the support may be a collodion emulsion. The support may comprise cellulose acetate, regenerated cellulose or other synthetic colloids, which may be lacquered on both sides. A thin film having emulsions on both sides may be temporarily mounted on water-permeable paper or on aluminium foil. The emulsions may be coated on both sides of regenerated cellulose or transparent paper, which may be then glued on stronger paper. Materials having a single layer comprising three sets of silver-halide emulsion grains, one set green sensitized, another orange-sensitized, and a third infra-red sensitized. A developing agent containing several dimethylamino groups or other basic residues may be employed. The insoluble coupling components may be in two or one of the emulsions only, the colour development of the remaining emulsions being effected with a colour developer containing a developing agent oxidizing directly to the desired colour, with a colour developer containing a developing agent whose oxidation product couples with unoxidized developing agent to give the desired colour, or with a colour developer containing a dissolved coupling component. Alternatively an insoluble coupling developing agent may be in the appropriate emulsions. The coupling components may have different coupling speeds; one may couple in the presence of borax and another only in the presence of sodium-carbonate. The coupling components may be dispersed in 10 per cent gelatine solution before adding to the emulsion. The coupling components may be deposited on or adsorbed by the silver halide grains, or may be formed withiri the emulsion after ripening. They may be precipitated in emulsions of low gelatine content and further gelatine added later, or precipitated in centrifuged silver bromide emulsion or in silver bromide separated from a gelatine emulsion, redispersed in water, or glycerine or other water miscible liquid, dispersed in gelatine, washed, and sensitized. The coupling components may be dissolved in alcoholic alkali, added to the gelatine silver halide emulsion, and precipitated by the addition of acid. The gelatine content is then brought to the correct value. A yellow filter consisting of dyed dextrine, gum arabic, or stearic acid may be placed in front of the top blue-sensitive emulsion. A colloidal silver antihalation layer may be arranged on either side of the support. The materials may be contain a sound record in one, two or three layers, preferably in the layer nearest the support, or the sound record may be in a fourth infra-red sensitized layer. The sound record may be at any stage of the processing, the element being.first dried. The sound record may be of the variable area type, or a combination of the variable density and variable width type. Specifications 376,746, 376,794, 376,795, 440,032, 440,089, 447,092, 458,664, 475,784, 475,786, 498,869, 498,870, 498,871, 498,875, 499,185, 500,826, (as open to inspection under Sect. 91), 503,752, 503,814, 503,816, 503,817, 503,818, 503,819, 503,820, 503,821, 503,823, 503,824, 503,825, 503,827, 503,939, and 503,941 also are referred to.