Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/04—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with macromolecular additives; with layer-forming substances
  • G03C1/047—Proteins, e.g. gelatine derivatives; Hydrolysis or extraction products of proteins
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/0051—Tabular grain emulsions
  • G03C1/0053—Tabular grain emulsions with high content of silver chloride
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/0051—Tabular grain emulsions
  • G03C2001/0055—Aspect ratio of tabular grains in general; High aspect ratio; Intermediate aspect ratio; Low aspect ratio
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C2200/00—Details
  • G03C2200/03—111 crystal face

Definitions

• the present invention deals with a photographic emulsion comprising tabular silver halide grains rich in chloride with improved sensitometric properties and to a photographic material containing such an emulsion.
• High aspect ratio tabular grains exhibit several pronounced photographic advantages. Thanks to their particular morphology greater amounts of spectral sensitizers can be adsorbed per mole silver halide compared to classical globular grains. As a consequence such spectrally sensitized tabular grains show an improved speed-granularity relationship and a wide separation between their blue speed and minus blue speed. Sharpness of photographic images can be improved using tabular grains thanks to their lower light scattering properties again compared to conventional globular emulsion grains. In color negative materials the conventional sequence of the light sensitive layers can be altered and the yellow filter layer can be omitted.
• An emulsion is generally understood to be a "tabular grain emulsion" when tabular grains account for at least 50 percent of total grain projected area.
• a grain is generally considered to be a tabular grain when the ratio of its equivalent circular diameter to its thickness is at least 2.
• the equivalent circular diameter of a grain is the diameter of a circle having an area equal to the projected area of the grain.
• Tabular silver halide grains rich in chloride can show a (111) crystal habit of their major parallel faces or they can show a (100) crystal habit of their major parallel faces.
• most attention was devoted to the preparation of (111) chloride rich tabular grains.
• Maskasky US 4,400,463 describes the preparation of a new crystallographic form of tabular silver halide grains rich in chloride by performing the precipitation in the presence of a special peptizer having a thioether linkage and an aminoazaindene growth modifier.
• Maskasky US 4,713,323 discloses the preparation of thin (111) tabular grains by a precipitation technique wherein oxidized gelatin is used.
• Tufano US 4,804,621 describes a process for preparing chloride rich (111) tabular grains in the presence of aminoazapyridine growth modifiers.
• EP 0 481 133 describes the presence of adenine-like compounds in the preparation of chloride rich (111) tabular grains using conventional gelatin, and Maskasky US 5,183,732 discloses similar compounds.
• Maskasky further describes triaminopyrimidines in US 5,185,239, xanthine derivatives in US 5,178,998, and other heterocyclic compounds in US 5,178,997, all as growth modifiers in the preparation of chloride rich (111) tabular emulsions.
• the present invention extends the teachings on tabular emulsions rich in chloride.
• the objects of the present invention are realized by providing a process for the preparation of a photographic emulsion comprising one or more precipitation steps in a reaction vessel, said emulsion comprising tabular grains, containing at least 50 mole % of chloride, wherein at least 50 % of the total projected area of all grains is provided by said tabular grains, and wherein said tabular grains exhibit an average aspect ratio of at least 5, an average thickness of at most 0.5 ⁇ m, and an average diameter of at least 0.6 ⁇ m, characterized in that during said one or more precipitation steps a gelatin binder is present in said reaction vessel which is substantially free of calcium ions.
• the tabular emulsion grains prepared according to the process of the invention contain at least 90 % of chloride, occupy at least 80 % of the total projected area, show an aspect ratio between 8 and 16 and have a thickness of at most 0.2 ⁇ m.
• the tabular emulsion is a silver iodochloride emulsion containing substantially no bromide.
• the substantially calcium free gelatin is at the same time an oxidized gelatin having a methionine content of less than 30 ⁇ mol/g.
• the calcium content of most commercial high-quality inert gelatins is about 0.4 % or about 100 mmol/kg.
• the basis for a high-quality gelatin preferably consists of pure, degreased hard cattle bones.
• the bones are treated with acid in order to remove calcium and magnesium phosphates.
• This is followed by an alkaline hydrolysis, mostly by means of calcium hydroxide, of the residual collagen resulting in gelatin.
• an alkaline hydrolysis mostly by means of calcium hydroxide, of the residual collagen resulting in gelatin.
• the calcium ions bound to specific amino acids of the polypeptide, exchange with protons.
• the alkaline hydrolysis with calcium hydroxide the polypeptide again takes up calcium ions upto saturation.
• the non-washable calcium concentration is about 0.5 % or 125 mmol/kg.
• slightly acidifying during washing the calcium content can be reduced to about 0.4 % or 100 mmol/kg.
• Calcium free gelatin is obtained by cation exchange by means of an ion exchange resin, preferably a so-called mixed-bed resin.
• an ion exchange resin preferably a so-called mixed-bed resin.
• substantially calcium free gelatin as gelatin with a calcium content below 40 ppm which is about the analytical detection limit.
• JP-A 04-321026 a black-and-white multicontrast material is disclosed using a specific calcium poor gelatin.
• JP-A- 02-300745 a specific AgX material is described comprising gelatin with a calcium content of less than 100 ppm.
• oxidized gelatin a gelatin having a methionine content of less than 30 ⁇ mol/g.
• Gelatin can be oxidized by means of e.g. hydrogen peroxide.
• a publication on the determination of methionine and its oxides in gelatin can be found in J. Phot. Sci. , Vol. 41, (1993), p. 172-175, by S. Tani and T. Tani.
• the emulsion precipitation can be principally performed by one double jet step it is preferred to perform a sequence of a nucleation step, at least one physical ripening step, and at least one growth step.
• a nucleation step preferably 0.5 % to 5.0 % is precipitated during said nucleation step which consists preferably of an approximately equimolecular addition of silver and halide salts.
• the rest of the silver and halide salts is added during one or more consecutive double jet growth steps.
• the different steps of the precipitation can be alternated by physical ripening steps.
• an increasing flow rate of silver and halide solutions is preferably established, e.g. a linearly increasing flow rate.
• the flow rate at the end is about 3 to 5 times greater then at the start of the growth step. These flow rates can be monitored by e.g. magnetic valves.
• the pAg is preferably maintained at a constant value corresponding to a silver potential preferably about 100 milli-Volt measured by a silver versus an Ag/AgCl Ingold electrode.
• the pH is preferably established at a value of at least 4.0, most preferably around 6.0.
• gelatin concentration of from about 0.05 % to 5.0 % by weight in the dispersion medium.
• This gelatin is calcium free according to the invention. Additional gelatin is added in a later stage of the emulsion preparation, e.g. after washing, to establish optimal coating conditions and/or to establish the required thickness of the coated emulsion layer.
• This gelatin can be conventional calcium containing non-oxidized gelatin.
• a gelatin / silver halide ratio ranging from 0.3 to 1.0 is then obtained, wherein silver halide is expressed as silver nitrate.
• the chloride rich tabular grains prepared in accordance with the present invention show a (111) crystal habit.
• a crystal habit modifier is present during the emulsion preparation.
• this crystal habit modifier is a 2-hydroaminoazine, most preferably an aminoazaindene compound.
• this aminoazaindene compound is adenine.
• the habit modifier used in connection with the present invention can be added at any stage of the silver halide precipitation procedure e.g. before the start of the precipitation, during the nucleation step, during a physical ripening stage or during one or more of the growth steps.
• the substance can be added to the dispersion medium itself as a solid or as a predissolved aqueous solution; alternatively the substance can be dissolved in one or more of the solutions which are entered into the dispersion medium, e.g. in one or more of the halide or silver salt solutions.
• wash technique in order to remove the excess of soluble salts is applied.
• Any conventional wash technique can be used e.g. washing with several water portions after flocculation by an inorganic salt or by a polymeric flocculating agent like polystyrene sulphonic acid.
• ultrafiltration is used as wash technique.
• the emulsions containing tabular chloride rich silver halide grains in accordance with the present invention can be chemically sensitized as described e.g. in "Chimie et Physique Photographique” by P. Glafkides, in “Photographic Emulsion Chemistry” by G.F. Duffin, in “Making and Coating Photographic Emulsion” by V.L. Zelikman et al, and in "Die Grundlagen der Photographischen Sawe mit Silberhalogeniden” edited by H. Frieser and published by Akademische Verlagsgesellschaft (1968).
• chemical sensitization can be carried out by effecting the ripening in the presence of small amounts of compounds containing sulphur e.g.
• the emulsions can be sensitized also by means of gold-sulphur ripeners, or gold-selenium ripeners, or gold-sulphur-selenium ripeners, or by means of reductors e.g. tin compounds as described in GB 789,823, amines, hydrazine derivatives, formamidine-sulphinic acids, and silane compounds.
• reductors e.g. tin compounds as described in GB 789,823, amines, hydrazine derivatives, formamidine-sulphinic acids, and silane compounds.
• the silver halide emulsions under consideration can be spectrally sensitized with methine dyes such as those described by F.M. Hamer in "The Cyanine Dyes and Related Compounds", 1964, John Wiley & Sons.
• Dyes that can be used for the purpose of spectral sensitization include cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, hemicyanine dyes, styryl dyes and hemioxonol dyes.
• Particularly valuable dyes are those belonging to the cyanine dyes, merocyanine dyes and complex merocyanine dyes.
• the scope of the present invention further encompasses a photographic material prepared according to the process described.
• this photographic material is a radiographic recording material.
• This photographic element containing one or more emulsions prepared in accordance with the present invention can be composed of one single emulsion layer, as is the case for many applications, or it can be built up by two or even more emulsion layers.
• the photographic material can contain several non-light sensitive layers, e.g. a protective layer, one or more backing layers, one or more subbing layers, and one or more intermediate layers e.g. filter layers.
• a protective layer e.g. a protective layer, one or more backing layers, one or more subbing layers, and one or more intermediate layers e.g. filter layers.
• the silver halide emulsion layer(s) of the photographic material in accordance with the present invention or the non-light-sensitive layers may comprise compounds preventing the formation of fog or stabilizing the photographic characteristics during the production or storage of the photographic elements or during the photographic treatment thereof.
• Many known compounds can be added as fog-inhibiting agent or stabilizer to the silver halide emulsion. Suitable examples are e.g.
• heterocyclic nitrogen-containing compounds such as benzothiazolium salts, nitroimidazoles, nitrobenzimidazoles, chlorobenzimidazoles, bromobenzimidazoles, mercaptothiazoles, mercaptobenzothiazoles mercaptobenzimidazoles, mercaptothiadiazoles, aminotriazoles, benzotriazoles (preferably 5-methyl-bensotriazole), nitrobenzotriazoles, mercaptotetrazoles, in particular 1-phenyl-5-mercapto-tetrazole, mercaptopyrimidines, mercaptotriazines, benzothiazoline-2-thione, oxazoline-thione, triazaindenes, tetrazaindenes and pentazaindenes, especially those described by Birr in Z.
• benzothiazolium salts such as benzothiazolium salts, nitroimidazoles, nitrobenzimidazoles, chlorobenz
• the gelatin binder of the photographic materials under consideration can be hardened with appropriate hardening agents such as those of the epoxide type, those of the ethylenimine type, those of the vinylsulfone type e.g. 1,3-vinylsulphonyl-2-propanol or methylenebisvinylsulphon, chromium salts e.g. chromium acetate and chromium alum, aldehydes e.g. formaldehyde, glyoxal, and glutaraldehyde, N-methylol compounds e.g. dimethylolurea and methyloldimethylhydantoin, dioxan derivatives e.g.
• appropriate hardening agents such as those of the epoxide type, those of the ethylenimine type, those of the vinylsulfone type e.g. 1,3-vinylsulphonyl-2-propanol or methylenebisviny
• the photographic element used in connection with the present invention may further comprise various kinds of surface-active agents in the photographic emulsion layer or in at least one other hydrophilic colloid layer.
• Suitable surface-active agents include non-ionic agents such as saponins, alkylene oxides e.g.
• polyethylene glycol polyethylene glycol/polypropylene glycol condensation products, polyethylene glycol alkyl ethers or polyethylene glycol alkylaryl ethers, polyethylene glycol esters, polyethylene glycol sorbitan esters, polyalkylene glycol alkylamines or alkylamides, silicone-polyethylene oxide adducts, glycidol derivatives, fatty acid esters of polyhydric alcohols and alkyl esters of saccharides; anionic agents comprising an acid group such as a carboxy, sulpho, phospho, sulphuric or phosphoric ester group; ampholytic agents such as aminoacids, aminoalkyl sulphonic acids, aminoalkyl sulphates or phosphates, alkyl betaines, and amine-N-oxides; and cationic agents such as alkylamine salts, aliphatic, aromatic, or heterocyclic quaternary ammonium salts, aliphatic or heterocyclic ring
• Development acceleration can be accomplished with the aid of various compounds, preferably polyalkylene derivatives having a molecular weight of at least 400 such as those described in e.g. US 3,038,805 - 4,038,075 - 4,292,400.
• the photographic element in connection with the present invention may further comprise various other additives such as e.g. compounds improving the dimensional stability of the photographic element, UV-absorbers, spacing agents and plasticizers.
• Suitable additives for improving the dimensional stability of the photographic element are e.g. dispersions of a water-soluble or hardly soluble synthetic polymer e.g. polymers of alkyl(meth)acrylates, alkoxy(meth)acrylates, glycidyl (meth)acrylates, (meth)acrylamides, vinyl esters, acrylonitriles, olefins, and styrenes, or copolymers of the above with acrylic acids, methacrylic acids, Alpha-Beta-unsaturated dicarboxylic acids, hydroxyalkyl (meth)acrylates, sulphoalkyl (meth)acrylates, and styrene sulphonic acids.
• a water-soluble or hardly soluble synthetic polymer e.g. polymers of alkyl(meth)acrylates, alkoxy(meth)acrylates, glycidyl (meth)acrylates, (meth)acrylamides, vinyl esters,
• UV-absorbers are e.g. aryl-substituted benzotriazole compounds as described in US 3,533,794, 4-thiazolidone compounds as described in US 3,314,794 and 3,352,681, benzophenone compounds as described in JP-A 2784/71, cinnamic ester compounds as described in US 3,705,805 and 3,707,375, butadiene compounds as described in US 4,045,229, and benzoxazole compounds as described in US 3,700,455.
• UV-absorbers are especially useful in colour recording materials where they prevent the fading by light of the colour images formed after processing.
• spacing agents can be present of which, in general, the average particle size is comprised between 0.2 and 10 micron. Spacing agents can be soluble or insoluble in alkali. Alkali-insoluble spacing agents usually remain permanently in the photographic element, whereas alkali-soluble spacing agents usually are removed therefrom in an alkaline processing bath. Suitable spacing agents can be made e.g. of polymethyl methacrylate, of copolymers of acrylic acid and methyl methacrylate, and of hydroxypropylmethyl cellulose hexahydrophthalate. Other suitable spacing agents have been described in US 4,614,708.
• the photographic material can contain several non light sensitive layers, e.g. an anti-stress top layer, one or more backing layers, and one or more intermediate layers eventually containing filter- or antihalation dyes that absorb scattering light and thus promote the image sharpness.
• Suitable light-absorbing dyes are described in e.g. US 4,092,168, US 4,311,787 and DE 2,453,217.
• One or more backing layers can be provided at the non-light sensitive side of the support.
• These layers which can serve as anti-curl layer can contain e.g. matting agents like silica particles, lubricants, antistatic agents, light absorbing dyes, opacifying agents, e.g. titanium oxide and the usual ingredients like hardeners and wetting agents.
• the support of the photographic material may be opaque or transparent, e.g. a paper support or resin support.
• a paper support preference is given to one coated at one or both sides with an ⁇ -olefin polymer, e.g. a polyethylene layer which optionally contains an anti-halation dye or pigment.
• an organic resin support e.g. cellulose nitrate film, cellulose acetate film, polyvinylacetal) film, polystyrene film, polyethylene terephthalate film, polycarbonate film, polyvinylchloride film or poly- ⁇ -olefin films such as polyethylene or polypropylene film.
• the thickness of such organic resin film is preferably comprised between 0.07 and 0.35 mm.
• These organic resin supports are preferably coated with a subbing layer which can contain water insoluble particles such as silica or titanium dioxide.
• the photographic material containing a tabular emulsion according to the present invention can be image-wise exposed by any convenient radiation source in accordance with its specific application.
• processing conditions and composition of processing solutions are dependent from the specific type of photographic material in which the tabular grains containing emulsions prepared according to the present invention are applied.
• an automatically operating processing apparatus is used provided with a system for automatic replenishment of the processing solutions.
• Emulsion A tabular silver chloride emulsion, comparative emulsion, low degree of gelatin oxidation
• a nucleation step was performed by introducing solution A and solution B1 simultaneously in dispersion medium C both at a flow rate of 60 ml/min during 30 seconds. After a physical ripening time of 20 min during which the temperature was raised to 70 °C, a growth step was performed by introducing by a double jet during 29 minutes solution A starting at a flow rate of 5 ml/min and linearly increasing the flow rate to an end value of 13.7 ml/min, and solution B1 at an increasing flow rate as to maintain a constant mV-value, measured by a silver electrode versus an Ag/AgCl Ingold Reference Electrode, of + 108 mV.
• This growth step was followed by a second growth step where by a double jet during 16 minutes solution A was introduced into the dispersion medium at a flow rate of 5 ml/min and solution B1 at a varying flow rate as to increase the mV-value, measured by a silver electrode versus a Ag/AgCl Ingold Reference Electrode, up to + 135 mV.
• a third growth step was performed by introducing by a double jet during 50 minutes solution A starting at a flow rate of 5 ml/min and linearly increasing the flow rate to an end value of 20 ml/min, and solution B1 at an increasing flow rate as to maintain a constant mV-value, measured by a silver electrode versus a Ag/AgCl Ingold Reference Electrode, of + 135 mV.
• the pH value of the said dispersing medium was adjusted to a value of 3.0 with sulphuric acid, and the emulsion was cooled down to room temperature.
• the obtained flocculate was decanted and washed three times with an amount of 4 l of demineralized water in order to remove the soluble salts present.
• the thus obtained silver chloride tabular emulsion showed the grain characteristics as illustrated in Table 1 (see furtheron).
• the average diameter d EM , average thickness t, average aspect ratio AR were obtained from electron microscopic photographs: the diameter of the grain was defined as the diameter of the circle having an area equal to the projected area of the grain as viewed in said photographs.
• the average sphere equivalent diameter d M obtained from the measurement of electric reduction currents obtained by reduction of a silver halide grain with a microscopically fine electrode is given: the sphere equivalent diameter was defined as the diameter of a hypothetical spherical grain with the same volume as the corresponding tabular grain.
• Emulsion B tabular silver chloride emulsion, comparative emulsion, high degree of gelatin oxidation
• Emulsions C tabular silver chloride emulsion, inventive emulsion, low degree of gelatin oxidation
• Emulsions D tabular silver chloride emulsion, inventive emulsion, high degree of gelatin oxidation
• the mV-value of every emulsion was adjusted to +158 mV with sodium chloride and the pH-value was set at 5.5 with sodium hydroxide.
• the amounts of the chemical ripening agents were adapted to the crystal size of the emulsions.
• Chemical ripening agents were gold thiocyanate, sodium thiosulphate as a source of sulphur and toluene thiosulphonic acid was used as predigestion agent.
• the amounts of each chemical ripening were optimized in order to obtain an optimal fog-sensitivity relationship after 4 hours at 57°C.
• each emulsion was stabilized with 1-p-carboxyphenyl-5-mercaptotetrazole and after addition of conventional coating additives the solutions were coated simultaneously together with a protective layer containing 1.3 g gelatine per m 2 per side on both sides of a polyethylene terephthalate film support having a thickness of 175 ⁇ m.
• the resulting photographic material contained at each side an amount of silver halide corresponding to 3.6 grams of AgNO 3 per m 2 and an amount of gelatin corresponding to 3.12 g/m 2 .
• the density as a function of the light dose was measured and therefrom were determined the following parameters:

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• 1996
  • 1996-05-21 EP EP96201371A patent/EP0809135A1/de not_active Withdrawn

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