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
  • G03C1/485—Direct positive emulsions
• • 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
  • G03C1/025—Physical treatment of emulsions, e.g. by ultrasonics, refrigeration, pressure
• • 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
• • 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
  • G03C1/09—Noble metals or mercury; Salts or compounds thereof; Sulfur, selenium or tellurium, or compounds thereof, e.g. for chemical sensitising
  • G03C2001/091—Gold
• • 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
  • G03C1/09—Noble metals or mercury; Salts or compounds thereof; Sulfur, selenium or tellurium, or compounds thereof, e.g. for chemical sensitising
  • G03C2001/095—Disulfide or dichalcogenide compound
• • 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
  • G03C1/09—Noble metals or mercury; Salts or compounds thereof; Sulfur, selenium or tellurium, or compounds thereof, e.g. for chemical sensitising
  • G03C2001/097—Selenium
• • 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
  • G03C1/34—Fog-inhibitors; Stabilisers; Agents inhibiting latent image regression
  • G03C2001/348—Tetrazaindene

Definitions

• This invention relates to photography, and more particularly, to a new method for the reduction sensitization of photographic silver halide emulsions.
• spectral sensitization the optical range of sensitivity, is increased, while in chemical sensitization, the overall sensitivity of a photographic emulsion is improved.
• the present invention is concerned primarily with the latter type of sensitization.
• Reduction sensitization is extremely useful since it can be additive to the former two forms of chemical sensitization.
• an object of this invention to provide an improved method of reduction sensitizing photographic silver halide emulsions. Still another object of my invention is to provide a new method of reduction sensitization which is relatively easy to apply and which requires no chemical treatment. It is a further object of my invention to provide a method of reduction sensitization which obviates the critical features inherent in chemical procedures of reduction sensitization. Another object of this invention is to further increase the speed of sulfur-type and/or noble metal sensitized silver halide emulsions by the reduction sensitizing method disclosed in this invention. It is still a further object to provide high speed reductionsensitized emulsions with low fogging propensity as well as improved keeping stability. It is an object ofmy invention to provide an improved nonchemical method of reduction sensitization of photographic silver halide emulsions by electrolytic means. Other objects of my invention will appear herein.
• the aboveo'bjects are accom- 3,411,917 Patented Nov. 19, 1968 plished by passing D.C. electric current through an aqueous silver halide photographic emulsion.
• a direct electrical current For example, through an aqueous silver halide photographic emulsion is passed by means of inert electrodes a direct electrical current.
• carbon or silver electrodes are eminently suitable for use in this connection.
• any voltage which will supply sufficient potential to force the electric current through the emulsion can be used, ordinarily a value within the range of 3-12 volts would be employed for an electrode spacing of 3 inches.
• Variation of treating conditions is possible as may be selected by the individual operator in any particular situation.
• the emulsion may be conveniently sensitized in accordance with the invention while subjected to stirring or other agitation and at a temperature assuring good liquidity for example 40 C.
• the present invention makes possible a more advantageous combination of reduction sensitization, noble metal sensitization and sulfur-type sensitization, while maintaining, within controllable limits, fog and stability of the treated emulsions.
• the electrolysis can optionally be performed either before or after the other sensitizing treatments. Especially useful results have been obtained where the treatment was performed following the other sensitizing operations.
• My electrical method of reduction sensitizing photographic silver halide emulsions can be used with emulsions having a gelatin vehicle. It operates advantageously with emulsions containing a mixture of gelatin and one or more other hydrophilic colloids such as polyvinyl alcohol, gum arabic, ethyl acrylate-acrylic acid copolymer, butyl acrylate-acrylic acid copolymer, etc.
• My invention is not confined to any particular sulfurtype sensitizer or group of sulfur-type sensitizers, although the following are particularly useful in practicing my invention: allylisothiourea, allylthiourea, allylisothiocyanate, phenylisothiocyanate, phenylthiourea, sodium thiosulfate, thiocarbanilide, thiourea, thiosemicarbazide, thioacetamide, thioformamide, thiobarbituric acid, etc.
• Such well known sensitizers have been previously described in Sheppard U.S. Patent 1,574,944, issued Mar. 2, 1926; Sheppard et al. U.S. Patent 1,623,499, issued Apr. 5, 1927; Sheppard et al. U.S. Patent 2,410,689, issued Nov. 5, 1946, etc.
• Noble metal salts or compounds useful in sensitizing emulsions are also well known to those skilled in the art and comprise auric trichloride, sodium chloroaurate, potassium chloroaurite, potassium ibromaurite, potassium iodoaurite, potassium iodoaurate, potassium aurithiocyanate, potassium aurichloride, auric sulfate, sodium auric chloride, potassium auric bromide, sodium auric bromide, alkali metal aurous thiosulfate, alkali metal aurous sulfite, thiourea-auric chloride complex, auric chloride- 3-ethyl-5-[ (3-ethyl) 2 (3H)-benzoxazolyldene)ethylideneJrhodanine addition product (e.g., Damschroder et al. U.S. Patent 2,642,361, issued June 16, 1953), etc. Typical gold sensitizers are described in Waller et al. U.
• EXAMPLE 1 To 317 grams of optimally finished sulfur-gold sensitized emulsion containing 0.10 mole of silver halide and 24.5 grams of gelatin, was added 0.20 gram of 4-hydroxy- 6-methyl-1,3,3a,7-tetraazaindene antifoggant in 6.0 cc. of water. The pH of the emulsion was adjusted to 6.0 and silver rod electrodes of about A inch in diameter and 3 inches in length were immersed in the emulsion. Current was passed through the emulsion for 3 minutes by means of the electrodes. The current source was two 6-volt dry cells wired in series which provided a current from approximately 80 to 120 ma. This corresponded to a current density at the electrodes of about ma./cm.
• the emulsion pH was adjusted to 6.4 and the emulsion pAg was adjusted to 8.3.
• Water and additional gelatin were added and the emulsion was coated on transparent film support at a silver coverage of 540 mg./ft. and a gelatin coverage of 1225 mg./ft.
• the emulsion coating was dried, sensitometrically exposed in an Eastman 1B sensitometer, and developed for 5 minutes at a temperature of 68 F. in a developing solution of the following composition:
• the film samples were fixed, Washed, and dried in the conventional manner.
• Electrolyzed coating 182 2. l0 0. 08
• EXAMPLE 2 Y A fine grain negative silver bromoiodide gelatin emult Rel. Speed Fog Nonelectrolyzed coating 100 0. 10 Electrolyzed coating 145 0. 23
• electrolysis increased the fog level of this particular emulsion used; but after allowance is made for this fog, it is seen that electrolysis has increased the emulsion speed by approximately That the occurrence of fog is not a necessary feature of the electrolytic process of my invention is shown in the following example.
• the new method of reduction sensitization of my invention is also applicable in the presence within an emulsion of other known stabilizing compounds such as the triazoles of Heimbach and Kelly U.S. Patent 2,444,608, issued July 6, 1948; the zinc and cadmium salts of Jones U.S. Patent 2,839,405, issued June 17, 1958; the carboxymethylmercapto compounds of Murray, Reynolds and Van Allan U.S. Patent 2,819,965, issued Jan. 14, 1958; and the disulfides of Kodak Belgian Patent 569,317, issued July 31, 1958.
• Examples 4, 5 and 6 show respectively the electrolysis effect on emulsions which (a) bear no prior chemical sensitization, (b) are sulfur sensitized, and (c) are sulfurgold sensitized.
• EXAMPLE 4 Medium grain silver bromoiodide gelatin emulsion containing 2 gm./silver mole of 4-hydroxy-6-methyl-1, 3,3a,7-tetraazaindene but having no chemical sensitization was subjected to a direct current electrolysis as described in Example 1. The photographic product obtained was tested in the manner previously described Sulfur sensitized coarse-grain silver bromoiodide gelatin emulsion containing no 4-hy-droxy-6-methyl-1,3,3a,7- tetraazaindene was employed as the emulsion in a run similar to that of Example 1. The following results were obtained:
• EXAMPLE 6 3g ⁇ Fog Sulfur-gold and selenium-gold sensitized medium-grain S 1 h dr 6 th 1133 7 silver bromoiodide gelatin emulsions containing 2 gm./ 1 B,2,;; g; j Xjffiffi j M3 5 silver mole of 4-hydroxy-6-methyl-1,3,3a,7-tetraazain- Strang e v viitgg ggn gs gvgr 11 y o y-fino 0 12 6 dene were electrolyzed as described in Example 1.
• Photographic speed increasing compounds can be used in emulsions which are reduction sensitized by the electrolytic method of my invention.
• Such compounds can be of the quaternary ammonium type of Carroll US. Patent 2,271,623, issued Feb. 3, 1942; Carroll and Allen US. Patent 2,288,226, issued June 30, 1942; and Carroll and Spence US. Patent 2,334,864, issued Nov. 23, 1943; or the polyethylene glycol type of Carroll and Beach US. Patent 2,708,162, issued May 10, 1955; or the quaternary ammonium salts and polyethylene glycols of Piper US. Patent 2,886,437, issued May 12, 1959; as well as the thiopolymers of Graham and Sagal US. Patent 3,046,129, issued July 24, 1962, and Dann and Chechak US. Patent 3,046,134, issued July 24, 1962.
• the electrolytic procedure of my invention is also applicable when a higher degree of reduction even up to complete fogging of a silver halide emulsion is desired, as for example in the preparation of photographic direct positive materials.
• the reduction of silver halide grains for the preparation of direct positive materials is commonly achieved either by the addition to a photographic negative emulsion of compounds such as formaldehyde (see Kendall and Hill, US. Patent 2,541,472) or stannous chloride or by exposing the emulsion to high intensity light radiation.
• my invention also provides a new method for reduction fogging of photographic emulsions for use as direct positive materials.
• This method consists generally of subjecting an emulsion to electrolysis as described above, in which electrolytic potential, time of treatment, and other conditions are selected in order to achieve the degree of reduction desired.
• electrolytic potential electrolytic potential
• time of treatment time of treatment
• other conditions are selected in order to achieve the degree of reduction desired.
• the practice of my invention envisions the combination of conventional treatment by chemical addenda with electrolytic reduction to achieve the degree of reduction needed in a particular circumstance.
• the speed increase from electrolysis appears to be the result of an improvement in granularity efiiciency rather than a development efiect. This is shown by two pieces of evidence. First, the sensitometric speed gain from electrolysis is independent of the degree of development. Secondly, the speed obtained from electrolysis is not accompanied by any increase in the granularity of the film.
• a method of sensitizing an aqueous silver halide photographic emulsion which comprises passing a direct electrical current having a voltage of 3-12 volts therethrough.
• a method of sensitizing a sulfur-sensitized aqueous silver halide photographic emulsion which comprises passing a direct electrical current having a voltage of 3-12 volts therethrough.
• a method of sensitizing a noble-metal sensitized aqueous silver halide photographic emulsion which comprises passing a direct electrical current having a voltage of 3-12 volts therethrough.
• a method of sensitizing a selenium sensitized aqueous silver halide photographic emulsion which comprises passing a direct electrical current having a voltage of 3-12 volts therethrough.
• a method of sensitizing an aqueous silver halide photographic emulsion containing an antifoggant which comprises passing a direct electrical current having a voltage of 3-12 volts therethrough.
• a method of sensitizing an aqueous silver halide photographic emulsion which comprises passing therethrough a direct electrical current having a voltage of 3- 12 volts using silver electrodes.
• a method of sensitizing an aqueous silver halide photographic emulsion which comprises passing therethrough a direct electrical current having a voltage of 3-12 volts using carbon electrodes.
• a method of producing a fogged aqueous silver halide photographic emulsion useful in the production of photographic direct positive materials which comprises passing a direct electrical current having a voltage of 3-12 volts through an aqueous silver halide photographic emulsion until said fogged aqueous silver halide photographic emulsion is obtained.

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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)
• Spectroscopy & Molecular Physics (AREA)
• Electrolytic Production Of Metals (AREA)
• Silver Salt Photography Or Processing Solution Therefor (AREA)
• Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)

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  • GB GB1143673D patent/GB1143673A/en active Active
• 1965
  • 1965-04-29 US US451992A patent/US3411917A/en not_active Expired - Lifetime

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