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
  • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
  • G03C1/08—Sensitivity-increasing substances
  • G03C1/28—Sensitivity-increasing substances together with supersensitising substances
  • G03C1/29—Sensitivity-increasing substances together with supersensitising substances the supersensitising mixture being solely composed of dyes ; Combination of dyes, even if the supersensitising effect is not explicitly disclosed
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B23/00—Methine or polymethine dyes, e.g. cyanine dyes
  • C09B23/02—Methine or polymethine dyes, e.g. cyanine dyes the polymethine chain containing an odd number of >CH- or >C[alkyl]- groups
  • C09B23/06—Methine or polymethine dyes, e.g. cyanine dyes the polymethine chain containing an odd number of >CH- or >C[alkyl]- groups three >CH- groups, e.g. carbocyanines
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B23/00—Methine or polymethine dyes, e.g. cyanine dyes
  • C09B23/10—The polymethine chain containing an even number of >CH- groups
• • 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
  • G03C1/485—Direct positive emulsions
  • G03C1/48515—Direct positive emulsions prefogged
  • G03C1/48523—Direct positive emulsions prefogged characterised by the desensitiser
  • G03C1/4853—Direct positive emulsions prefogged characterised by the desensitiser polymethine dyes

Definitions

• X and X represent oxygen, sulphur, selenium or N(R wherein R has the significance given for R R Z, and Z represent the atoms necessary to close a fusedon aromatic nucleus of the benzene series,
• R is hydrogen, alkyl, aralkyl, or aryl
• X is an anion but does not exist when one of R R and R contains an anionic group.
• the combination of dyes used has a supersensitizing effect on the emulsion.
• the total speed is markedly increased as compared with the use of either dye alone and less stain is produced.
• the present invention relates to the spectral sensitization of direct-positive silver halide emulsions.
• Photographic emulsions comprising in the interior of the silver halide grains, centres promoting the deposition of photolytic silver are known, e.g. from UK. patent specifications 1,011,062 filed May 15, 1962, 1,151,781 filed Apr. 15, 1966 both by Eastman Kodak Co., and 1,027,146 filed Aug. 30, 1963 by Agfa AG.
• emulsions having ripening nuclei in the interior of the grains are prepared by admixture of a coarse-grained silver halide emulsion, which has been ripened chemically and comprises ripening nuclei at the surface of the grains, with a fine-grain silver halide emulsion followed by physical ripening of the mixture, whereby the large grains grow at the cost of the small grains so that the unripened fine-grain emulsion deposits around the ripened coarsegrain emulsion.
• a method of making a photographic direct-positive material which comprises forming gnains of a first lightsensitive silver salt, treating these grains so as to produce centres therein, which promote the deposition of photolytic silver, covering the treated grains with a layer of a second light-sensitive silver salt and fogging the resulting emulsion before or after coating on a support.
• gTOuP wherein A has the same significance as described in the United Kingdom patent specification 886,270 filed June 24, 1957 by Gevaert Photo-Produoten N.V., cyclohexyl, allyl, benzyl including substituted benzyl such as carboxybenzyl and sulphobenzyl, and phenyl including substituted phenyl such as carboxyphenyl;
• X and X stand for oxygen, sulphur, selendium or the group N(R wherein R has the same significance as R1 R4,
• Z and Z stand for the atoms necessary to complete a fused-on aromatic nucleus of the benzene series which may be substituted, e.g. by halogen, alkyl, substituted alkyl, alkoxy, alkylsulphonyl, sulphamoyl, etc.;
• R stands for hydrogen, alkyl, aralkyl or aryl
• X stands for an anion of the type contained in cyanine dye salts, such as chloride, bromide, iodide, perchlorate, benzene sulphonate, toluene sulphonate, methyl sulphate, ethyl sulphate, etc. or X does not exist when one of R R and R itself contains an anionic group, in which case the dye is a betaine dye.
• Direct-positive silver halide emulsions having a central core of silver halide containing centres promoting the deposition of photolytic silver and over said core an outer shell of silver halide that has been fogged, can be obtained by the following steps:
• the precipitation of the silver halide is preferably carried out by simultaneous addition of the halide salt solution and the silver salt solution to the gelatin solution and keeping the pAg value as constant as possible during precipitation.
• the silver halide grains have a substantially uniform diameter, preferably at least by weight of said grains having a diameter that is within about 40% of the mean grain diameter.
• the said silver halide cores may be treated physically or chemically according to any of the known procedures for producing the said centres promoting the deposition of photolytic silver. Such centres are produced preferaby by chemical sensitization and any of the usual methods may be used therefor.
• the cores may be digested with naturally active gelatin or with a labile sulphur compound.
• the cores may be sensitized chemically with noble metal sensitizers, e.g.
• Gold sensitization preferably occurs by means of a mixture of a water-soluble gold salt such as g0ld(IIl)chloride and a thiocyanate froming complexes with gold and having a solvent action on the silver halide grains e.g. alkali metal and ammonium thiocyanates.
• Reduction sensitization may also occur by digestion of the cores at low pAg values (I. Phot. Sci. 6, 33 (1958)).
• the centres promoting the deposition of photolytic silver may also be produced by subjecting the cores to fogging by exposure to radiation of either low or high intensity.
• the outer shell of silver halide provided over the silver halide core of the silver halide grains is prepared by precipitating silver halide around the silver halide cores formed, which have been treated previously physically or chemically as described above so as to produce centres promoting the deposition of photolytic silver.
• the outer shell is then fogged uniformly at the surface to such an extent that it is developable by conventional surface image developing compostions.
• Fogging may occur by exposure, before or after coating of the emulsion, to actinic radiation but preferably fogging occurs by chemical means. Chemical fogging can be effected by chemically sensitzing to fog using one of the chemical sensitizing methods outlined above. Fogging can be eifected successfully by means of reducing agents e.g.
• Fogging of the silver halide shell may also be elfected by high pH and/ or low pAg silver halide precipitating conditions.
• the centres promoting the deposition of photolytic silver in the interior of the silver halide grains are produced by chemical sensitization with-a gold compound together with a reduction sensitizer e.g. thiourea dioxide, also called formamidine sulphinic acid and derivatives thereof, whereas the external fogging of the composite silver halide granules occurs with the same reduction sensitizer.
• a reduction sensitizer e.g. thiourea dioxide, also called formamidine sulphinic acid and derivatives thereof
• thiourea dioxide also called formamidine sulphinic acid and derivatives thereof
• the merocyanine and carbocyanine dyes used according to the present invention are added to the silver halide emulsion preferably after fogging of the outer silver halide shell. They can be used in widely varying concentrations but are employed generally at concentrations in the range of 50 mg. to 500 mg., preferably 100 mg. to 300 mg. per mole of silver halide.
• the composite silver halide granules formed may contain silver chloride, silver bromide, or silver iodide or mixtures thereof.
• a core of silver bromide can be coated with a shell of silver chloride or a mixture of silver bromide and silver iodide, or a core of silver chloride can have deposited thereon a shell of silver bromide.
• the composite silver halide granules preferably have an interior core of silver bromide, around which silver bromide has been deposited.
• Gelatin is used preferably as vehicle for the composite silver halide granules but like in other silver halide emulsions the gelatin may be replaced wholly or partly by other hydrophilic colloids, e.g. colloidal albumin, zein, agar-agar, polyvinyl alcohols, polyvinyl acetals, hydrolyzed cellulose esters or ethers, etc.
• hydrophilic colloids e.g. colloidal albumin, zein, agar-agar, polyvinyl alcohols, polyvinyl acetals, hydrolyzed cellulose esters or ethers, etc.
• the directpositve silver halide emulsions comprising in the interior of the silver halide grains centres promoting the deposition of photolytic silver may also comprise all kinds of known emulsion ingredients for direct-positive emulsions for example wetting agents, development accelerators, optical brightening agents, hardeners, stabilizers, etc They may comprise selenium compounds as described in copending application No. 15472/70 filed Apr. 1, 1970 by Gevaert-Agfa N.V. for increasing the reversal speed of the direct positive silver halide elements.
• the direct-positive emulsions sensitized spectrally in accordance with the present invention can be coated on any of the wide variety of supports.
• Typical supports include, e.g. cellulose nitrate film, cellulose acetate film, polyvinyl acetal film, polystyrene film, polyethylene terephthalate film and films of other polyesters as well as paper, paper coated with e.g. polyethylene or polypropylene, glass and metal.
• Spectrally sensitized direct-positive silver halide emulsions according to the present invention can be employed for colour photography, e.g. emulsions containing colourforming couplers or emulsions to be developed by solutions containing couplers.
• the emulsions may be used in silver halide diffusion transfer processes and in colour transfer processes. They can be processed in monobath processes or in stabilization type processes.
• lith-developers as described in French patent specification 2,042,173 filed Mar. 24, 1970 by Gevaert-Agfa N.V. in order to obtain direct-positive images with very steep gradation curve.
• lith developer there is understood a developing composition for light-exposed silver halide containing a hydrogen sulphite-addition compound of an aliphatic aldehyde or ketone e.g. formaldehyde hydrogen sulphite, and hydroquinone as the sole developing agent.
• EXAMPLE 1 75 ml. of a 3 N aqueous solution of potassium bromide and 75 ml. of a 3 N aqueous solution of silver nitrate were introduced simultaneously at a rate of ml.
• the internal ripening was effected.
• 3.5 ml. of a 10' molar solution of formamidine sulphinic acid were added and the emulsion digested for 30 minutes at 50 C.
• the pH was lowered to 6 .5 and 1.5 ml. of an aqueous 0.08% by weight solution of gold(HI)chloride and 1.5 m1. of aqueous 2% by weight solution of ammonium thiocyanate were added. After said addition the digestion was continued for 10 minutes at 50 C.
• the precipitation was then continued (second precipitation) as follows: an aqueous solution of ammonia was added to obtain a pH value of 9.3 whereupon 665 ml. of an aqueous 3 N potassium bromide solution and 665 ml. of an aqueous 3 N silver nitrate solution were introduced at a rate of 19ml. per minute. During precipitation the pAg value was maintained at a value corresponding.
• the pAg was again adjusted to a value corresponding to an E.M.F. of +20 mv. (Ag/saturated calomel electrode) and the pH of the emulsion was adjusted to 6.5.
• the external fogging of the composite silver bromide granules formed was then carried out for minutes at 55 C. with 9 ml. of a 10- molar aqueous solution of formamidine sulphinic acid per kg. emulsion, containing g. of silver bromide and 80 g. of gelatin.
• the emulsion was divided into several aliquot portions.
• the emulsion portions were cooled to 35 C. and the sensitizers listed in the table below were added in the amount given.
• the emulsion portions were kept for 30 min. at 35 C. whereupon per kg. 1 g. of saponin was added as coating aid.
• 500 mg. of formaldehyde were added per kg. for hardening purposes.
• the various emulsion samples were then coated on a polyethylene terephthalate resin support and dried.
• the density in the exposed areas (minimum density) dye 5 (61115 is a measure of the brightness of the whites and is denoted N N m the tables by D In the tables are also given the maximum density I (D obtained as well as the silver bromide content HeCOiS N N SOzCHz per sq. m. of the materials examined. l
• Example 5 10 wherein the said centres are formed by chemical sensitization of the interior core of silver halide.
• a direct-positive photographic silver halide emulsion which comprises silver halide grains having a central core of silver halide containing centres promoting the deposition of photolytic silver and over said core and outer shell of silver halide, which has been fogged, wherein said outer shell comprises adsorbed thereto a Z-pyridine-rhodanine merocyanine dye corresponding to the following general Formula I and a carbocyanine dye corresponding to the following General Formula II:
• R R R and R stand for a saturated or unsaturated aliphatic group, a cycloaliphatic group or an aryl group,
• X, and X stand for oxygen, sulphur, selenium, or the group N(R wherein R has the same significance as given for R -R Z and 2: stand for the atoms necessary to close a fused-on aromatic nucleus of the benzene series,
• R stands for hydrogen, or lower alkyl
• X stands for an anion but does not exist when one of R R and R itself contains an anionic group.
• a direct-positive photographic element which comprises a support and at least one layer of an emulsion according to claim 1.

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• Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• General Physics & Mathematics (AREA)
• Organic Chemistry (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Silver Salt Photography Or Processing Solution Therefor (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=10409095

Family Applications (1)

Country Status (7)

Cited By (10)

Families Citing this family (2)

• 1970
  • 1970-08-14 GB GB3935370A patent/GB1335851A/en not_active Expired
• 1971
  • 1971-07-07 DE DE19712133868 patent/DE2133868A1/de active Pending
  • 1971-07-09 BE BE769752A patent/BE769752A/xx unknown
  • 1971-07-09 FR FR7125562A patent/FR2101617A5/fr not_active Expired
  • 1971-07-14 CA CA118,220A patent/CA971814A/en not_active Expired
  • 1971-07-14 US US00162612A patent/US3759713A/en not_active Expired - Lifetime
  • 1971-08-05 JP JP5927171A patent/JPS5434329B1/ja active Pending

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