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
• • 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
  • G03C1/10—Organic substances
  • G03C1/12—Methine and polymethine dyes
• • 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

Definitions

• This invention relates to silver halide photographic materials which are less susceptible to pressure fog, and methods of making same.
• Pressure applied to silver halide photographic emulsion coatings can produce both reversible and irreversible effects on the sensitometry of the photographic product.
• pressure sensitivity can be described as an effect which causes the photographic sensitometry of film products to change after the application of some kind of a mechanical stress to a coated photographic film.
• the prior art such as described in James, The Theory of the Photographic Process, 4th Ed., MacMillan (1977), describe various mechanisms in association with the various types of pressure sensitivities observed with photographic products, characterized in that the transmission of mechanical and thermal stress to silver halide crystals causes a change in sensitometry for the photographic products.
• US-A-4,925,783 and US-A-4,996,140 describe a method of improving sensitizing dye absorption and pressure blackening performance by adding a sensitizing dye during desalting.
• US-A-4,659,654 describes a photographic material with reduced pressure blackening which has silver halide particles with a specific iodide composition and containing certain cyanine dyes. These patents provide a very wide range for the amount of sensitizing dye which may be added and they do not indicate any correlation between the amount of sensitizing dye added and the reduction of pressure fog.
• Sensitizing dyes are typically added at a level which will yield optimum emulsion performance in terms of various parameters including speed, fog, and gamma.
• the preferred concentration of sensitizing dye is usually from 80% to 100% saturation coverage.
• antifoggants include various tetraazaindenes and mercaptotetrazoles as disclosed in Research Disclosure, No. 308119, p. 993, (December 1989). Normally such antifoggants are used as melt additives, that is they are added to the emulsion after chemical sensitization and just prior to coating.
• US-A-3,732,104 indicates that tetraazaindenes may be added at any time during emulsion preparation, but preferably just before coating.
• US-A-4,863,844 relates to a more heat stable photographic element characterized in that certain mercaptotetrazoles are added after the formation of silver halide grains up to the completion of chemical sensitization.
• US-A-3,637,393 relates to a photographic material with reduced fog which contains certain mercaptotetrazoles and states that it is preferable to add the mercaptotetrazoles during sensitization or prior to coating.
• US-A-4,912,026 relates to a light-sensitive material with BF contamination resistance and pH variation resistance which contains certain mercaptotetrazoles and states that it is preferable to add the mercaptotetrazoles during sensitization or prior to coating. All of these references are directed toward the reduction of fog created by chemical processes. None of these references are directed to the elimination of pressure fog through the combination of the above antifoggants with reduced sensitizing dye levels.
• the silver halide emulsion is contained in the silver halide emulsion unit furthest from the support. In another embodiment the silver halide emulsion is a bromoiodide emulsion. In additional embodiments the silver halide emulsion is a tabular emulsion or an octahedral emulsion.
• This invention further provides a method of preparing a photographic silver halide emulsion comprising precipitation and spectral/chemical sensitization steps to enable a spectrally sensitized silver halide emulsion containing spectral sensitizing dye at a concentration of less than 75% of its saturation coverage; characterized in that an antifogging amount of a heterocyclic antifoggant which contains an acidic sulfur or nitrogen silver binding site is added prior to or during spectral/chemical sensitization.
• the photographic elements of this invention contain at least one emulsion which is sensitized with a sensitizing dye at a concentration less than approximately 75% of its saturation coverage.
• the saturation coverage for any given emulsion substrate and any given sensitizing dye can be determined using the Langmuir Isotherm method as described in James, The Theory of the Photographic Process, pp. 236-239, 4th Edition, (1977, Macmillan Publishing Company, Inc.).
• the concentration of sensitizing dye must, however, be high enough to adequately sensitize the emulsion. This will vary depending on the emulsion type and can be determined by methods known to those skilled in the art. Generally, the concentration should be at least 10% of the saturation coverage.
• the preferred concentration of sensitizing dye for this invention is from 25 to 75% of its saturation coverage.
• the more preferred use is in the unit located toward the front surface of the pack. This is because the silver halide emulsion unit which is furthest from the support is more susceptible to pressure fog because it is most directly impacted by the external pressure causing element.
• the silver halide emulsion unit furthest from the support may actually be more than one layer with the layers being sensitive to the same given region of the spectrum, that is yellow, green, or red. Each layer may also contain more than one emulsion.
• the emulsion of this invention may be used in one or more of the layers in the unit or in one or more emulsions in a layer.
• the preferred use of this invention is with emulsions appropriate for use in the blue light sensitive unit.
• the preferred blue-light absorbing sensitizing dyes are thiacyanine dyes.
• the more preferred blue-light absorbing sensitizing dyes are benzothiazole cyanine dyes.
• the most preferred dye is Although the preferred use of this invention is in the unit furthest from the support it is also useful in other pressure sensitive layers. All the layers of the photographic element are vulnerable to pressure fog created when the photographic element is dried during manufacturing. Therefore this invention may also be used with red and green light absorbing sensitizing dyes in the magenta and cyan emulsion layers of conventional photographic elements.
• Photographic emulsions are generally prepared by precipitating silver halide crystals in a colloidal matrix by methods conventional in the art.
• the colloid is typically a hydrophilic film forming agent such as gelatin, alginic acid, or derivatives thereof.
• the sensitizing dye may be added to the emulsion by conventional methods.
• the dye may be added at any point during the spectral/chemical sensitization process and before or during the heat spike which effects chemical sensitization. Combinations of sensitizing dyes may be used as long as the final concentration meets the requirement of this invention.
• the more preferred antifoggants are 5-bromo tetraazaindene and 1-phenyl 5-mercaptotetrazole. Particular antifoggants may be preferred for certain emulsion types, emulsion halide structures, sensitizing dyes, and sensitizing dye levels. Combinations of these antifoggants may also be used.
• the amount of antifoggant which needs to be added depends on many factors such as emulsion type, other sensitizers, such as thiocyanate, gold or sulfur containing compounds, emulsion halide structure, and emulsion size. In general 0.1 to 105 mg/mol Ag is adequate to produce the desired results. The preferred amount of antifoggant to be added is from 1 to 103 mg/mol Ag. This level should be co-optimized with the other sensitizer levels.
• This invention is useful with those emulsions which are sensitive to pressure fog.
• the pressure sensitivity can be tested by subjecting portions of a coated sample to a roller apparatus fitted with a sandblasted hardened steel wheel.
• the magnitude of the pressure effect can be quantified by comparing the Dmin density of an unpressured portion to that of a pressured portion of the same sample.
• the increase in density of the pressured portion is the pressure fog.
• the magnitude of the pressure fog will depend on the width, diameter and roughness of the wheel, the pressure applied to the wheel, and the speed at which the wheel is rolled over the sample (with the emulsion layers facing the roughened wheel).
• a typical configuration would be to apply 42 psi pressure on a 4 mm wide by 30 mm diameter sandblasted steel wheel at a linear speed of 300 mm/second.
• emulsions sensitive to pressure fog will generally exhibit a pressure fog density that is greater than 5% of the total possible density (Dmax).
• the silver halide emulsions employed in the elements of this invention can be either negative-working or positive-working.
• suitable emulsions and their preparation are described in Research Disclosure Sections I and II and the publications cited therein.
• Some of the suitable vehicles for the emulsion layers and other layers of elements of this invention are described in Research Disclosure Section IX and the publications cited therein.
• the photographic elements can be coated on a variety of supports including but not limited to those described in Research Disclosure Section XVII and the references described therein.
• Photographic elements can be exposed to actinic radiation, typically in the visible region of the spectrum, to form a latent image as described in Research Disclosure Section XVIII and then processed to form a visible dye image examples of which are described in Research Disclosure Section XIX.
• Processing to form a visible dye image includes the step of contacting the element with a color developing agent to reduce developable silver halide and oxidize the color developing agent. Oxidized color developing agent in turn reacts with the coupler to yield a dye.
• the magnitude of the pressure effect was quantified by comparing the blue Dmin density of an unpressured portion of a sample to that of a pressured portion of the same sample.
• the increase in density observed with the pressured portion of a sample is the pressure-fog.
• Smaller values of the pressure fog are superior in that they indicate that a particular film composition is less susceptible to forming unsightly marks and blemishes.
• a 3.3 ⁇ m ECD by 0.12 ⁇ m thick tabular bromoiodide emulsion was prepared by conventional methods as described in US-A-5,061,616.
• the emulsion consisted of a uniform 2 mole percent iodide tabular host which accounted for 70% of the total silver. On top of this host was precipitated a thin bromoiodide lamina which was 30 mole percent iodide and amounted to 7% of the total silver.
• the remainder of the emulsion was a secondary lamina composed of silver bromide.
• Samples B-1 to B-6 were sensitized with the blue light absorbing sensitizing dye SD-1 and with sulphur and gold in the standard manner.
• Samples B-1 through B-6 The parameters of the sensitization of Samples B-1 through B-6 are shown in Table 1.
• Samples B-1 and B-2 contained 1.15 mmol/mol Ag of SD-1, or approximately 86% of saturation coverage.
• Samples B-3 through B-6 contained 0.80 mmoles/mol Ag, of SD-1 or approximately 60% of the saturation coverage.
• the two antifoggants 1-(3-acetamidophenyl)-5-mercaptotetrazole (APMT) and 5-bromo tetrazaindene (BrTAI) were added during spectral/chemical sensitization.
• the sensitizations also included 3-(2-methylsulfamolyehtyl)-benzathiazolium tetrafluoroborate (FM-1) which is an antifoggant requiring a ring opening mechanism in order to activate its acidic sulfur atom.
• FM-1 3-(2-methylsulfamolyehtyl)-benzathiazolium tetrafluoroborate
• the order of addition was thiocyanate, dye, sulfur, gold, FM-1, antifoggant (if any), and finally the chemical ripening step at elevated temperature.
• Samples B-8 through B-11 contained 0.40 mmoles/mol Ag, of SD-1 or approximately 52% of the saturation coverage.
• the antifoggant 1-phenyl 5-mercaptotetrazole (PMT) was added during spectral/chemical sensitization.
• the sensitizations also included 3-(2-methylsulfamolyehtyl)-benzathiazolium tetrafluoroborate (FM-1).
• the chemicals are listed below in the order of addition.
• Example 2 The emulsion of Example 2, sensitized and containing PMT as in Sample B-11, was coated in the Least Blue Sensitive Layer (Layer 10) of the photographic film of this example.
• a three color photographic film was prepared as follows using conventional surfactants, antifoggants and the materials indicated. After providing a developable image and then processing in accordance with the Kodak C-41 process (British Journal of Photographic, pp. 196-198 (1988)) excellent results for example improved color, sharpness, granularity and neutral scale, were obtained. All silver halide emulsions were stabilized with 1.75 gm 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene per mole of silver added prior to coating. All silver halide emulsions were sensitized with the appropriate spectral red, green and blue sensitizing dyes.

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• Materials Engineering (AREA)
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• Spectroscopy & Molecular Physics (AREA)
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Citations (3)

• 1993
  • 1993-04-14 DE DE1993622429 patent/DE69322429T2/de not_active Expired - Fee Related
  • 1993-04-14 EP EP19930106042 patent/EP0566075B1/de not_active Expired - Lifetime
  • 1993-04-16 JP JP8984393A patent/JPH0619027A/ja active Pending

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