EP0699950B1 - Emulsions aux grains tabulaires ultraminces avec gestion nouvelle de dopants - Google Patents

Emulsions aux grains tabulaires ultraminces avec gestion nouvelle de dopants Download PDF

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EP0699950B1
EP0699950B1 EP19950420240 EP95420240A EP0699950B1 EP 0699950 B1 EP0699950 B1 EP 0699950B1 EP 19950420240 EP19950420240 EP 19950420240 EP 95420240 A EP95420240 A EP 95420240A EP 0699950 B1 EP0699950 B1 EP 0699950B1
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Prior art keywords
emulsion
silver
tabular grains
emulsions
silver halide
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EP0699950A1 (fr
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Richard Lee C/O Eastman Kodak Company Daubendiek
Joseph Charles Eastman Kodak Company Lighthouse
Donald Lee C/O Eastman Kodak Company Black
Myra Toffolon C/O Eastman Kodak Company Olm
Joseph Charles C/O Eastman Kodak Company Deaton
Xin C/O Eastman Kodak Company Wen
Timothy Richard c/o Eastman Kodak Company Gersey
Robert Don C/O Eastman Kodak Company Wilson
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Eastman Kodak Co
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Eastman Kodak Co
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Priority claimed from US08/297,430 external-priority patent/US5503971A/en
Priority claimed from US08/297,195 external-priority patent/US5576168A/en
Priority claimed from US08/296,562 external-priority patent/US5503970A/en
Priority claimed from US08/359,251 external-priority patent/US5494789A/en
Priority claimed from US08/441,489 external-priority patent/US5614358A/en
Application filed by Eastman Kodak Co filed Critical Eastman Kodak Co
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    • 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
    • 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
    • G03C1/46—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein having more than one photosensitive layer

Definitions

  • the invention relates to silver halide photography. More specifically, the invention relates to improved spectrally sensitized silver halide emulsions and to multilayer photographic elements incorporating one or more of these emulsions.
  • ECD refers to the diameter of a circle having an area equal to the projected area of a silver halide grain.
  • the halides are named in order of ascending concentrations.
  • dopant is employed to indicate any occlusion within a silver halide grain crystal lattice structure other than silver and halide ions.
  • high intensity reciprocity failure also referred to as HIRF
  • HIRF high intensity reciprocity failure
  • Kofron et al U.S. Patent 4,439,520 ushered in the current era of high performance silver halide photography.
  • Kofron et al disclosed and demonstrated striking photographic advantages for chemically and spectrally sensitized tabular grain emulsions in which tabular grains having a diameter of at least 0.6 ⁇ m and a thickness of less than 0.3 ⁇ m exhibit an average aspect ratio of greater than 8 and account for greater than 50 percent of total grain projected area. In the numerous emulsions demonstrated one or more of these numerical parameters often far exceeded the stated requirements.
  • Kofron et al recognized that the chemically and spectrally sensitized emulsions disclosed in one or more of their various forms would be useful in color photography and in black-and-white photography (including indirect radiography). Spectral sensitizations in all portions of the visible spectrum and at longer wavelengths were addressed as well as orthochromatic and panchromatic spectral sensitizations for black-and-white imaging applications. Kofron et al employed combinations of one or more spectral sensitizing dyes along with middle chalcogen (e.g., sulfur) and/or noble metal (e.g., gold) chemical sensitizations, although still other, conventional modifying compounds, such as metal compounds, were taught to be optionally present during grain precipitation.
  • middle chalcogen e.g., sulfur
  • noble metal e.g., gold
  • Maskasky I recognized that a site director, such as iodide ion, an aminoazaindene, or a selected spectral sensitizing dye, adsorbed to the surfaces of host tabular grains was capable of directing silver halide epitaxy to selected sites, typically the edges and/or corners, of the host grains. Depending upon the composition and site of the silver salt epitaxy, significant increases in speed were observed. Modifying compounds were taught to be optionally incorporated either in the host tabular grains or in the salt halide epitaxy.
  • Antoniades et al U.S. Patent 5,250,403 disclosed tabular grain emulsions that represent what were, prior to the present invention, in many ways the best available emulsions for recording exposures in color photographic elements, particularly in the minus blue (red and/or green) portion of the spectrum.
  • Antoniades et al disclosed tabular grain emulsions in which tabular grains having ⁇ 111 ⁇ major faces account for greater than 97 percent of total grain projected area.
  • the tabular grains have an equivalent circular diameter (ECD) of at least 0.7 ⁇ m and a mean thickness of less than 0.07 ⁇ m.
  • Tabular grain emulsions with mean thicknesses of less than 0.07 ⁇ m are herein referred to as "ultrathin" tabular grain emulsions. They are suited for use in color photographic elements, particularly in minus blue recording emulsion layers, because of their efficient utilization of silver, attractive speed-granularity relationships, and high levels of image sharpness, both in the emulsion layer and in underlying emulsion layers.
  • a characteristic of ultrathin tabular grain emulsions that sets them apart from other tabular grain emulsions is that they do not exhibit reflection maxima within the visible spectrum, as is recognized to be characteristic of tabular grains having thicknesses in the 0.18 to 0.08 ⁇ m range, as taught by Buhr et al, Research Disclosure, Vol. 253, Item 25330, May 1985.
  • multilayer photographic elements overlying emulsion layers with mean tabular grain thicknesses in the 0.18 to 0.08 ⁇ m range require care in selection, since their reflection properties differ widely within the visible spectrum.
  • ultrathin tabular grain emulsions in building multilayer photographic elements eliminates spectral reflectance dictated choices of different mean grain thicknesses in the various emulsion layers overlying other emulsion layers.
  • the use of ultrathin tabular grain emulsions not only allows improvements in photographic performance, it also offers the advantage of simplifying the construction of multilayer photographic elements.
  • Antoniades et al contemplated the incorporation of ionic dopants in the ultrathin tabular grains as taught by Research Disclosure, Vol. 308, December 1989, Item 308119, Section I, Paragraph D.
  • Kuno U.S. Patent 5,051,344 discloses silver iodobromide emulsions containing 0.1 to 4 mole percent iodide and, as grain dopants, 5 X 10 -9 to 1 X 10 -6 mole of an iridium compound and 5 X 10 -9 to 1 X 10 -6 mole of an iron compound per mole of silver.
  • the grains are of a core-shell structure with the core containing a higher iodide content (at least 3 mole percent greater) than the shell.
  • Kuno specifically prefers both the iridium and iron to be present in the shell.
  • the object is to achieve high contrast with high-illuminance short-duration exposure, rapid processing, and better safe-light handling.
  • the emulsions are intended to be responsive to high intensity, short duration exposures, but relatively unresponsive to the low levels of illumination provided by safe-lights.
  • Kuno recognizes that iridium reduces both high and low intensity reciprocity failure. Kuno's purpose in adding iron is to eliminate the effect of iridium in reducing low intensity reciprocity failure.
  • this invention is directed to a radiation-sensitive emulsion comprised of (1) a dispersing medium, (2) silver halide grains including tabular grains (a) having ⁇ 111 ⁇ major faces, (b) containing greater than 70 mole percent bromide, based on silver, (c) accounting for greater than 90 percent of total grain projected area, (d) exhibiting an average equivalent circular diameter of at least 0.7 ⁇ m, (e) exhibiting an average thickness of less than 0.07 ⁇ m, (f) containing an iridium dopant capable of reducing reciprocity failure over the exposure range of from 1 X 10 -2 to 1 X 10 -5 second and (g) having latent image forming chemical sensitization sites on the surfaces of the tabular grains, and (3) a spectral sensitizing dye adsorbed to the surfaces of the tabular grains, characterized in that the surface chemical sensitization sites include silver halide protrusions forming epitaxial junctions with the tabular grains, the protrusions (a) being located on up to 50 percent
  • this invention is directed to a photographic element comprised of (i) a support, (ii) a first silver halide emulsion layer coated on the support and sensitized to produce a photographic record when exposed to specular light within the minus blue visible wavelength region of from 500 to 700 nm, and (iii) a second silver halide emulsion layer capable of producing a second photographic record coated over the first silver halide emulsion layer to receive specular minus blue light intended for the exposure of the first silver halide emulsion layer, the second silver halide emulsion layer being capable of acting as a transmission medium for the delivery of at least a portion of the minus blue light intended for the exposure of the first silver halide emulsion layer in the form of specular light, characterized in that the second silver halide emulsion layer is comprised of an improved emulsion according to the invention.
  • the improved ultrathin tabular grain emulsions of the present invention are the first to employ a combination of iridium dopant in the ultrathin tabular grains and dopant modified silver halide epitaxy in their chemical sensitization to provide the advantages that can be realized by ultrathin tabular grain emulsions and to enhance the photographic speed and reduce the high intensity reciprocity failure that these emulsions otherwise exhibit.
  • the present invention has been realized by (1) overcoming a bias in the art against applying silver halide epitaxial sensitization to ultrathin tabular grain emulsions, (2) observing improvements in performance as compared to ultrathin tabular grain emulsions receiving only conventional sulfur and gold sensitizations, (3) observing larger improvements in sensitivity than expected, based on similar sensitizations of thicker tabular grains, and (4) avoiding thickening of ultrathin grains by locating a dopant in the silver halide epitaxy rather than in the tabular grains.
  • Antoniades et al avoided silver halide epitaxial sensitization, Antoniades et al taught to dope the ultrathin tabular grains following conventional practices. Antoniades et al did not appreciate that dopants can contribute to tabular grain thickening. Further, having specifically avoided any teaching of silver halide epitaxial sensitization, Antoniades et al saw no other doping alternative, except to locate the dopant in the ultrathin tabular grains.
  • Still another advantage is based on the observation of reduced unwanted wavelength absorption as compared to relatively thicker tabular grain emulsions similarly sensitized. A higher percentage of total light absorption was confined to the spectral region in which the spectral sensitizing dye or dyes exhibited absorption maxima. For minus blue sensitized ultrathin tabular grain emulsions native blue absorption was also reduced.
  • the emulsions investigated have demonstrated an unexpected robustness. It has been demonstrated that, when levels of spectral sensitizing dye are varied, as can occur during manufacturing operations, the silver salt epitaxially sensitized ultrathin tabular grain emulsions of the invention exhibit less variance in sensitivity than comparable ultrathin tabular grain emulsions that employ only sulfur and gold sensitizers.
  • the invention is directed to an improvement in spectrally sensitized photographic emulsions.
  • the emulsions are specifically contemplated for incorporation in camera speed color photographic films.
  • the emulsions of the invention can be realized by chemically and spectrally sensitizing any conventional ultrathin tabular grain emulsion in which the tabular grains
  • halides are named in their order of ascending concentration.
  • the tabular grains contain at least 0.25 (preferably at least 1.0) mole percent iodide, based on silver.
  • the saturation level of iodide in a silver bromide crystal lattice is generally cited as about 40 mole percent and is a commonly cited limit for iodide incorporation, for photographic applications iodide concentrations seldom exceed 20 mole percent and are typically in the range of from about 1 to 12 mole percent.
  • ultrathin tabular grain emulsions containing from 0.4 to 20 mole percent chloride and up to 10 mole percent iodide, based on total silver, with the halide balance being bromide, can be prepared by conducting grain growth accounting for from 5 to 90 percent of total silver within the pAg vs. temperature (°C) boundaries of Curve A (preferably within the boundaries of Curve B) shown by Delton, corresponding to Curves A and B of Piggin et al U.S. Patents 5,061,609 and 5,061,616.
  • chloride ion Under these conditions of precipitation the presence of chloride ion actually contributes to reducing the thickness of the tabular grains. Although it is preferred to employ precipitation conditions under which chloride ion, when present, can contribute to reductions in the tabular grain thickness, it is recognized that chloride ion can be added during any conventional ultrathin tabular grain precipitation to the extent it is compatible with retaining tabular grain mean thicknesses of less than 0.07 ⁇ m.
  • the ultrathin tabular grains accounting for at least 90 percent of total grain projected area contain at least 70 mole percent bromide, based on silver.
  • These ultrathin tabular grains include silver bromide, silver iodobromide, silver chlorobromide, silver iodochlorobromide and silver chloroiodobromide grains.
  • the ultrathin tabular grains include iodide, the iodide can be uni formly distributed within the tabular grains. To obtain a further improvement in speed-granularity relationships it is preferred that the iodide distribution satisfy the teachings of Solberg et al U.S. Patent 4,433,048, the disclosure of which is here incorporated by reference.
  • the tabular grains of the emulsions of the invention account for greater than 90 percent of total grain projected area.
  • Ultrathin tabular grain emulsions in which the tabular grains account for greater than 97 percent of total grain projected area can be produced by the preparation procedures taught by Antoniades et al and are preferred.
  • Antoniades et al reports emulsions in which substantially all (e.g., up to 99.8%) of total grain projected area is accounted for by tabular grains.
  • Delton reports that "substantially all" of the grains precipitated in forming the ultrathin tabular grain emulsions were tabular.
  • Providing emulsions in which the tabular grains account for a high percentage of total grain projected area is important to achieving the highest attainable image sharpness levels, particularly in multilayer color photographic films. It is also important to utilizing silver efficiently and to achieving the most favorable speed-granularity relationships.
  • the tabular grains accounting for greater than 90 percent of total grain projected area exhibit an average ECD of at least 0.7 ⁇ m.
  • the advantage to be realized by maintaining the average ECD of at least 0.7 ⁇ m is demonstrated in Tables III and IV of Antoniades et al.
  • ECD's are occasionally prepared for scientific grain studies, for photographic applications ECD's are conventionally limited to less than 10 ⁇ m and in most instances are less than 5 ⁇ m.
  • An optimum ECD range for moderate to high image structure quality is in the range of from 1 to 4 ⁇ m.
  • the tabular grains accounting for greater than 90 percent of total grain projected area exhibit a mean thickness of less than 0.07 ⁇ m. At a mean grain thickness of 0.07 ⁇ m there is little variance between reflectance in the green and red regions of the spectrum. Additionally, compared to tabular grain emulsions with mean grain thicknesses in the 0.08 to 0.20 ⁇ m range, differences between minus blue and blue reflectances are not large. This decoupling of reflectance magnitude from wavelength of exposure in the visible region simplifies film construction in that green and red recording emulsions (and to a lesser degree blue recording emulsions) can be constructed using the same or similar tabular grain emulsions.
  • mean thicknesses of the tabular grains are further reduced below 0.07 ⁇ m, the average reflectances observed within the visible spectrum are also reduced. Therefore, it is preferred to maintain mean grain thicknesses at less than 0.05 ⁇ m.
  • mean tabular grain thickness conveniently realized by the precipitation process employed is preferred.
  • ultrathin tabular grain emulsions with mean tabular grain thicknesses in the range of from about 0.03 to 0.05 ⁇ m are readily realized.
  • Daubendiek et al U.S. Patent 4,672,027 reports mean tabular grain thicknesses of 0.017 ⁇ m.
  • Preferred ultrathin tabular grain emulsions are those in which grain to grain variance is held to low levels.
  • Antoniades et al reports ultrathin tabular grain emulsions in which greater than 90 percent of the tabular grains have hexagonal major faces.
  • Antoniades also reports ultrathin tabular grain emulsions exhibiting a coefficient of variation (COV) based on ECD of less than 25 percent and even less than 20 percent.
  • COV coefficient of variation
  • ultrathin tabular grain nucleation is conducted employing gelatino-peptizers that have not been treated to reduce their natural methionine content while grain growth is conducted after substantially eliminating the methionine content of the gelatino-peptizers present and subsequently introduced.
  • a convenient approach for accomplishing this is to interrupt precipitation after nucleation and before growth has progressed to any significant degree to introduce a methionine oxidizing agent.
  • Maskasky U.S. Patent 4,713,320 (hereinafter referred to as Maskasky II), teaches to reduce methionine levels by oxidation to less than 30 ⁇ moles, preferably less than 12 ⁇ moles, per gram of gelatin by employing a strong oxidizing agent.
  • the oxidizing agent treatments that Maskasky II employ reduce methionine below detectable limits.
  • agents that have been employed for oxidizing the methionine in gelatino-peptizers include NaOCl, chloramine, potassium monopersulfate, hydrogen peroxide and peroxide releasing compounds, and ozone.
  • Gelatino-peptizers include gelatin--e.g., alkali-treated gelatin (cattle, bone or hide gelatin) or acid-treated gelatin (pigskin gelatin) and gelatin derivatives, e.g., acetylated or phthalated gelatin.
  • An iridium dopant capable of reducing high intensity reciprocity failure is incorporated in the tabular grains of the emulsion of the invention.
  • Specific examples of iridium dopants employed to reduce high intensity reciprocity failure are provided by Iwaosa et al U.S. Patent 3,901,711, Grzeskowiak et al U.S. Patent 4,828,962, Kuno U.S. Patent 5,051,344 and Yoshida et al U.S. Patent 5,229,263.
  • a more general survey of iridium dopants employed to reduce reciprocity failure and for other purposes is provided by B. H. Carroll, Iridium Sensitization: A Literature Review", Photographic Science and Engineering , Vol. 24, No.
  • the iridium dopant is incorporated in the crystal lattice structure of the grain in the form a hexacoordination complex satisfying the formula: (IV) [Ir +3 X 5 L'] m where
  • a convenient counter ion such as ammonium or alkali metal
  • ammonium or alkali metal is associated with the hexacoordination complex, but only the anionic portion of formula IV is actually incorporated within the crystal lattice structure.
  • the iridium can be in a +4 valence state, as illustrated, for example by Leubner et al U.S. Patent 4,902,611. However, the +4 iridium reverts to the +3 valence state upon incorporation. Chloride and bromide are preferred halide ligands.
  • the bridging ligand L' can also be a halide ligand or, alternatively, can take any convenient conventional form, including any of the various individual ligand forms disclosed in McDugle et al U.S. Patents 4,933,272, 4,981,781 and 5,037,732, Marchetti et al U.S. Patent 4,937,180, Keevert et al U.S. Patent 5,037,732 and Olm et al U.S. Patent 5,360,712.
  • the iridium dopant is preferably introduced following precipitation of at least 20 (most preferably 60) percent of the silver forming the tabular grains and before 90 (most preferably 80) of the silver forming the tabular grains has been precipitated. Addition of iridium earlier in the precipitation is avoided to avoid complicating ultrathin tabular grain nucleation while addition of iridium late in the precipitation is avoided to insure full incorporation of iridium within the interior of the ultrathin tabular grains.
  • Preferred concentrations of the iridium dopant can range up to about 300 (most preferably 250) molar parts per billion (mppb). Minimum effective iridium concentrations of 2.8 mppb have been reported, although concentrations of at least about 15 mppb are usually more convenient to use.
  • ultrathin tabular grains receive during chemical sensitization epitaxially deposited silver halide forming protrusions at selected sites on the ultrathin tabular grain surfaces.
  • the protrusions exhibit a higher overall solubility than the silver halide forming at least those portions of the ultrathin tabular grains that serve as epitaxial deposition host sites--i.e., that form an epitaxial junction with the silver halide being deposited.
  • solubility products, K sp , of AgCl, AgBr and AgI in water at temperatures ranging from 0 to 100°C are reported in Table 1.4, page 6, Mees, The Theory of the Photographic Process, 3rd Ed., Macmillan, New York (1966).
  • the solubility product of AgCl is 6.22 X 10 -10
  • AgBr is 2.44 X 10 -12
  • AgI is 6.95 X 10 -16 .
  • Requiring the epitaxially deposited protrusions to exhibit a higher overall solubility than at least those portions of the ultrathin tabular grains on which they are deposited reduces displacement of halide ions from the ultrathin tabular grains, thereby avoiding degradation of the ultrathin configuration of the tabular grains.
  • silver halide protrusions will in all instances be precipitated to contain at least a 10 percent, preferably at least a 15 percent and optimally at least a 20 percent higher chloride concentration than the host ultrathin tabular grains.
  • any increase in the iodide concentration of the face centered cubic crystal lattice structure of the epitaxial protrusions improves photographic performance
  • the addition of bromide ions along with chloride and iodide ions increases the amounts of iodide that can be incorporated in the silver halide epitaxy while, surprisingly, increasing the level of bromide does not detract from the increases in photographic speed and contrast observed to result from increased iodide incorporations.
  • the generally accepted solubilities of silver iodide in silver, bromide and silver chloride is 40 and 13 mole percent, respectively, based on total silver, with mixtures of silver bromide and chloride accommodating intermediate amounts of silver iodide, depending on the molar ratio of Br:Cl. It is preferred that the silver iodide in the epitaxy be maintained at less than 10 mole percent, based on total silver in the epitaxy. It is further preferred that the overall solubility of the silver halide epitaxy remain higher than that of the portions of the ultrathin tabular grains serving as deposition sites for epitaxial deposition.
  • the overall solubility of mixed silver halides is the mole fraction weighted average of the solubilities of the individual silver halides.
  • the highest levels of photographic performance are realized when the silver halide epitaxy contains both (1) the large differences in chloride concentrations between the host ultrathin tabular grains and the epitaxially deposited protrusions noted above and (2) elevated levels of iodide inclusion in the face centered cubic crystal lattice structure of the protrusions.
  • Maskasky I reports improvements in sensitization by epitaxially depositing silver halide at selected sites on the surfaces of the host tabular grains.
  • Maskasky I attributes the speed increases observed to restricting silver halide epitaxy deposition to a small fraction of the host tabular grain surface area. It is contemplated to restrict silver halide epitaxy to less than 50 percent of the ultrathin tabular grain surface area and, preferably, to a greater extent, as taught by Maskasky I.
  • Maskasky I teaches to restrict silver halide epitaxy to less than 25 percent, preferably less than 10 percent, and optimally less than 5 percent of the host grain surface area.
  • the ultrathin tabular grains contain a lower iodide concentration central region and a higher iodide laterally displaced region, as taught by Solberg et al, it is preferred to restrict the silver halide epitaxy to those portions of the ultrathin tabular grains that are formed by the laterally displaced regions, which typically includes the edges and corners of the tabular grains.
  • the iodide concentration of the epitaxial protrusions can be higher than the overall average concentration of the host ultrathin tabular grains without risking disruption of the ultrathin tabular grain structure, provided that the iodide concentrations of the portions of the tabular grains that provide the deposition sites of the epitaxial protrusions are higher than the iodide concentrations of the epitaxial protrusions.
  • silver halide epitaxy As low as 0.05 mole percent, based on total silver, where total silver includes that in the host and epitaxy, are effective in the practice of the invention. Because of the increased host tabular grain surface area coverages by silver halide epitaxy discussed above and the lower amounts of silver in ultrathin tabular grains, an even higher percentage of the total silver can be present in the silver halide epitaxy. However, in the absence of any clear advantage to be gained by increasing the proportion of silver halide epitaxy, it is preferred that the silver halide epitaxy be limited to 50 percent of total silver. Generally silver halide epitaxy concentrations of from 0.3 to 25 mole percent are preferred, with concentrations of from about 0.5 to 15 mole percent being generally optimum for sensitization.
  • Maskasky I teaches various techniques for restricting the surface area coverage of the host tabular grains by silver halide epitaxy that can be applied in forming the emulsions of this invention.
  • Maskasky I teaches employing spectral sensitizing dyes that are in their aggregated form of adsorption to the tabular grain surfaces capable of direct silver halide epitaxy to the edges or corners of the tabular grains.
  • Cyanine dyes that are adsorbed to host ultrathin tabular grain surfaces in their J-aggregated form constitute a specifically preferred class of site directors.
  • Maskasky I also teaches to employ non-dye adsorbed site directors, such as aminoazaindenes (e.g., adenine) to direct epitaxy to the edges or corners of the tabular grains.
  • site directors such as aminoazaindenes (e.g., adenine)
  • Maskasky I relies on overall iodide levels within the host tabular grains of at least 8 mole percent to direct epitaxy to the edges or corners of the tabular grains.
  • Maskasky I adsorbs low levels of iodide to the surfaces of the host tabular grains to direct epitaxy to the edges and/or corners of the grains.
  • the above site directing techniques are mutually compatible and are in specifically preferred forms of the invention employed in combination.
  • iodide in the host grains can nevertheless work with adsorbed surface site director(s) (e.g., spectral sensitizing dye and/or adsorbed iodide) in siting the epitaxy.
  • adsorbed surface site director(s) e.g., spectral sensitizing dye and/or adsorbed iodide
  • a dopant capable of providing shallow electron trapping sites in the silver halide epitaxy. This is achieved by employing within identified concentration levels and tabular grain locations, in relation to the tabular grain surfaces and the iridium dopant, a speed enhancing Group 8 dopant comprised of a divalent Group 8 metal ion (i.e., Fe +2 , Ru +2 or Os +2 ) and at least one coordination ligand more electron withdrawing than a fluoride ion.
  • the speed enhancing Group 8 dopant can be introduced as a hexacoordination complex satisfying the formula: (V) [ML 6 ] n where
  • At least four of the ligands are required to be anionic to facilitate incorporation of the dopant into the crystal lattice structure of the tabular grains.
  • the remaining two ligands can also be anionic or can take any convenient conventional neutral form, such as carbonyl, aquo or ammine ligands.
  • any higher number, up to and including all of the ligands can be more electronegative than a halide ion.
  • One common way of assessing electron withdrawing characteristics is by reference to the spectrochemical series of ligands, derived from the absorption spectra of metal ion complexes in solution, referenced in Inorganic Chemistry: Principles of Structure and Reactivity, by James E. Huheey, 1972, Harper and Row, New York and in Absorption Spectra and Chemical Bonding in Complexes by C. K. Jorgensen, 1962, Pergamon Press, London.
  • ox oxalate
  • dipy dipyridine
  • phen o -phenathroline
  • phosph 4-methyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane.
  • the spectrochemical series places the ligands in sequence in their electron withdrawing properties, the first (I - ) ligand in the series is the least electron withdrawing and the last (CO) ligand being the most electron withdrawing.
  • the underlining indicates the site of ligand bonding to the polyvalent metal ion.
  • ligands C N - and C O are especially preferred.
  • Other preferred ligands are thiocyanate ( N CS - ), selenocyanate ( N CSe - ), cyanate ( N CO - ), tellurocyanate ( N CTe - ) and azide (N 3 - ).
  • the metal M in the hexacoordination complex is Fe +2
  • the metal M in the hexacoordination complex is Os +2 satisfactory speed enhancement is observed with only one ligand more electron withdrawing than a halide ion, but at least two such ligands are preferred.
  • Ru +2 complexes it is preferred that at least three of the ligands be more electronegative than a halide ion.
  • the Group 8 coordination complexes when introduced can be associated with the same charge balancing counter ions as the iridium complexes, described above.
  • the ligands L can be selected from the same conventional ligands as L', described above (i.e., from any of the various individual ligand forms disclosed in McDugle et al U.S. Patents 4,933,272, 4,981,781 and 5,037,732, Marchetti et al U.S. Patent 4,937,180, Keevert et al U.S. Patent 5,037,732 and Olm et al U.S. Patent 5,360,712,).
  • Group 8 coordination complex dopants capable of enhancing speed when employed in combination with iridium dopants: SET-1 [Fe(CN) 6 ] -4 SET-2 [Ru(CN) 6 ] -4 SET-3 [Os(CN)6] -4 SET-4 [Fe(pyrazine)(CN) 5 ] -4 SET-5 [RuCl(CN) 5 ] -4 SET-6 [OsBr(CN) 5 ] -4 SET-7 [FeCO(CN) 5 ] -3 SET-8 [RuF 2 (CN) 4 ] -4 SET-9 [OsCl 2 (CN) 4 ] -4 SET-10 [Ru(CN) 5 (OCN)] -4 SET-11 [Ru(CN) 5 (N 3 )] -4 SET-12 [Os(CN) 5 (SCN)] -4 SET-13 [Fe(CN) 3 Cl 3 ] -3 SET-14 [Ru(CO) 2 (CN) 4 ] -1 SET-15
  • the Group 8 dopants are effective in conventional concentrations, where concentrations are based on the total silver, including both the silver in the tabular grains and the silver in the protrusions.
  • Generally shallow electron trap forming dopants are contemplated to be incorporated in concentrations of at least 1 X 10 -6 mole per silver mole (1 mppm) up to their solubility limit, typically up to about 5 X 10 -4 mole per silver mole (500 mppm).
  • Preferred concentrations are in the range of from about 10 -5 to 10 -4 mole per silver mole (10 to 100 mppm).
  • the advantages of placing the Group 8 dopant in the silver halide protrusions are that at this location (1) interference with favorable HIRF effects provided by iridium are eliminated, (2) the risk of dopant contributing to thickening of the ultrathin tabular grains is eliminated and (3) by locating the Group 8 dopant in the protrusions it is placed near the site of latent image formation, which generally occurs at or near the junction of the protrusions with the ultrathin tabular grains. Locating the dopant near the site of latent image formation increases the effectiveness of the dopant.
  • Silver halide epitaxy can by itself increase photographic speeds to levels comparable to those produced by substantially optimum chemical sensitization with sulfur and/or gold. Additional increases in photographic speed can be realized when the tabular grains with the silver halide epitaxy deposited thereon are additionally chemically sensitized with conventional middle chalcogen (i.e., sulfur, selenium or tellurium) sensitizers or noble metal (e.g., gold) sensitizers.
  • middle chalcogen i.e., sulfur, selenium or tellurium
  • noble metal e.g., gold
  • a specifically preferred approach to silver halide epitaxy sensitization employs a combination of sulfur containing ripening agents in combination with middle chalcogen (typically sulfur) and noble metal (typically gold) chemical sensitizers.
  • Contemplated sulfur containing ripening agents include thioethers, such as the thioethers illustrated by McBride U.S. Patent 3,271,157, Jones U.S. Patent 3,574,628 and Rosencrants et al U.S. Patent 3,737,313.
  • Preferred sulfur containing ripening agents are thiocyanates, illustrated by Nietz et al U.S. Patent 2,222,264, Lowe et al U.S. Patent 2,448,534 and Illingsworth U.S.
  • a preferred class of middle chalcogen sensitizers are tetra-substituted middle chalcogen ureas of the type disclosed by Herz et al U.S. Patents 4,749,646 and 4,810,626.
  • Preferred compounds include those represented by the formula: wherein
  • X is preferably sulfur and A 1 R 1 to A 4 R 4 are preferably methyl or carboxymethyl, where the carboxy group can be in the acid or salt form.
  • a specifically preferred tetra-substituted thiourea sensitizer is 1,3-dicarboxymethyl-1,3-dimethylthiourea.
  • Preferred gold sensitizers are the gold(I) compounds disclosed by Deaton U.S. Patent 5,049,485. These compounds include those represented by the formula: (VII) AuL 2 + X - or AuL(L 1 ) + X - wherein
  • Kofron et al discloses advantages for "dye in the finish" sensitizations, which are those that introduce the spectral sensitizing dye into the emulsion prior to the heating step (finish) that results in chemical sensitization.
  • Dye in the finish sensitizations are particularly advantageous in the practice of the present invention where spectral sensitizing dye is adsorbed to the surfaces of the tabular grains to act as a site director for silver halide epitaxial deposition.
  • Maskasky I teaches the use of J-aggregating spectral sensitizing dyes, particularly green and red absorbing cyanine dyes, as site directors. These dyes are present in the emulsion prior to the chemical sensitizing finishing step.
  • spectral sensitizing dyes When the spectral sensitizing dye present in the finish is not relied upon as a site director for the silver halide epitaxy, a much broader range of spectral sensitizing dyes are available.
  • the selection of J-aggregating blue absorbing spectral sensitizing dyes for use as site directors is specifically contemplated.
  • a general summary of useful spectral sensitizing dyes is provided by Research Disclosure, Dec. 1989, Item 308119, Section IV. Spectral sensitization and desensitization, A. Spectral sensitizing dyes.
  • the spectral sensitizing dye can act also as a site director and/or can be present during the finish, the only required function that a spectral sensitizing dye must perform in the emulsions of the invention is to increase the sensitivity of the emulsion to at least one region of the spectrum.
  • the spectral sensitizing dye can, if desired, be added to an ultrathin tabular grain according to the invention after chemical sensitization has been completed.
  • ultrathin tabular grain emulsions exhibit significantly smaller mean grain volumes than thicker tabular grains of the same average ECD, native silver halide sensitivity in the blue region of the spectrum is lower for ultrathin tabular grains.
  • blue spectral sensitizing dyes improve photographic speed significantly, even when iodide levels in the ultrathin tabular grains are relatively high.
  • ultrathin tabular grains depend almost exclusively upon the spectral sensitizing dye or dyes for photon capture.
  • spectral sensitizing dyes with light absorption maxima at wavelengths longer than 430 nm (encompassing longer wavelength blue, green, red and/or infrared absorption maxima) adsorbed to the grain surfaces of the invention emulsions produce very large speed increases. This is in part attributable to relatively lower mean grain volumes and in part to the relatively higher mean grain surface areas available for spectral sensitizing dye adsorption.
  • the emulsions of this invention and their preparation can take any desired conventional form.
  • a novel emulsion satisfying the requirements of the invention has been prepared, it can be blended with one or more other novel emulsions according to this invention or with any other conventional emulsion.
  • Conventional emulsion blending is illustrated in Research Disclosure Item 308119, cited above, Section I, Paragraph I.
  • the emulsions once formed can be further prepared for photographic use by any convenient conventional technique. Additional conventional features are illustrated by Research Disclosure Item 308119, cited above, Section II, Emulsion washing; Section VI, Antifoggants and stabilizers; Section VII, Color materials; Section VIII, Absorbing and scattering materials; Section IX, Vehicles and vehicle extenders; X, Hardeners; XI, Coating aids; and XII, Plasticizers and lubricants. The features of VII-XII can alternatively be provided in other photographic element layers.
  • novel epitaxial silver halide sensitized ultrathin tabular grain emulsions of this invention can be employed in any otherwise conventional photographic element.
  • the emulsions can, for example, be included in a photographic element with one or more silver halide emulsion layers.
  • a novel emulsion according to the invention can be present in a single emulsion layer of a photographic element intended to form either silver or dye photographic images for viewing or scanning.
  • this invention is directed to a photographic element containing at least two superimposed radiation sensitive silver halide emulsion layers coated on a conventional photographic support of any convenient type.
  • Exemplary photographic supports are summarized by Research Disclosure , Item 308119, cited above, Section XVII.
  • the emulsion layer coated nearer the support surface is spectrally sensitized to produce a photographic record when the photographic element is exposed to specular light within the minus blue portion of the visible spectrum.
  • the term "minus blue” is employed in its art recognized sense to encompass the green and red portions of the visible spectrum--i.e., from 500 to 700 nm.
  • specular light is employed in its art recognized usage to indicate the type of spatially oriented light supplied by a camera lens to a film surface in its focal plane--i.e., light that is for all practical purposes unscattered.
  • the second of the two silver halide emulsion layers is coated over the first silver halide emulsion layer.
  • the second emulsion layer is called upon to perform two entirely different photographic functions.
  • the first of these functions is to absorb at least a portion of the light wavelengths it is intended to record.
  • the second emulsion layer can record light in any spectral region ranging from the near ultraviolet ( ⁇ 300 nm) through the near infrared ( ⁇ 1500 nm). In most applications both the first and second emulsion layers record images within the visible spectrum.
  • the second emulsion layer in most applications records blue or minus blue light and usually, but not necessarily, records light of a shorter wavelength than the first emulsion layer. Regardless of the wavelength of recording contemplated, the ability of the second emulsion layer to provide a favorable balance of photographic speed and image structure (i.e., granularity and sharpness) is important to satisfying the first function.
  • the second distinct function which the second emulsion layer must perform is the transmission of minus blue light intended to be recorded in the first emulsion layer.
  • the presence of silver halide grains in the second emulsion layer is essential to its first function, the presence of grains, unless chosen as required by this invention, can greatly diminish the ability of the second emulsion layer to perform satisfactorily its transmission function.
  • an overlying emulsion layer e.g., the second emulsion layer
  • the second emulsion layer is hereinafter also referred to as the optical causer layer and the first emulsion is also referred to as the optical receiver layer.
  • overlying (second) emulsion layer can cause unsharpness in the underlying (first) emulsion layer is explained in detail by Antoniades et al, incorporated by reference, and hence does not require a repeated explanation.
  • Obtaining sharp images in the underlying emulsion layer is dependent on the ultrathin tabular grains in the overlying emulsion layer accounting for a high proportion of total grain projected area; however, grains having an ECD of less than 0.2 ⁇ m, if present, can be excluded in calculating total grain projected area, since these grains are relatively optically transparent. Excluding grains having an ECD of less than 0.2 ⁇ m in calculating total grain projected area, it is preferred that the overlying emulsion layer containing the silver halide epitaxy sensitized ultrathin tabular grain emulsion of the invention account for greater than 97 percent, preferably greater than 99 percent, of the total projected area of the silver halide grains.
  • the second emulsion layer consists almost entirely of ultrathin tabular grains.
  • the optical transparency to minus blue light of grains having ECD's of less 0.2 ⁇ m is well documented in the art.
  • Lippmann emulsions which have typical ECD's of from less than 0.05 ⁇ m to greater than 0.1 ⁇ m, are well known to be optically transparent.
  • Grains having ECD's of 0.2 ⁇ m exhibit significant scattering of 400 nm light, but limited scattering of minus blue light.
  • the tabular grain projected areas of greater than 97% and optimally greater than 99% of total grain projected area are satisfied excluding only grains having ECD's of less than 0.1 (optimally 0.05) ⁇ m.
  • the second emulsion layer can consist essentially of tabular grains contributed by the ultrathin tabular grain emulsion of the invention or a blend of these tabular grains and optically transparent grains. When optically transparent grains are present, they are preferably limited to less than 10 percent and optimally less than 5 percent of total silver in the second emulsion layer.
  • the advantageous properties of the photographic elements of the invention depend on selecting the grains of the emulsion layer overlying a minus blue recording emulsion layer to have a specific combination of grain properties.
  • the tabular grains contain photographically significant levels of iodide.
  • the iodide content imparts art recognized advantages over comparable silver bromide emulsions in terms of speed and, in multicolor photography, in terms of interimage effects.
  • Second, having an extremely high proportion of the total grain population as defined above accounted for by the tabular grains offers a sharp reduction in the scattering of minus blue light when coupled with an average ECD of at least 0.7 ⁇ m and an average grain thickness of less than 0.07 ⁇ m.
  • the mean ECD of at least 0.7 ⁇ m is, of course, advantageous apart from enhancing the specularity of light transmission in allowing higher levels of speed to be achieved in the second emulsion layer.
  • employing ultrathin tabular grains makes better use of silver and allows lower levels of granularity to be realized.
  • the presence of silver halide epitaxy allows unexpected increases in photographic sensitivity to be realized.
  • the photographic elements can be black-and-white (e.g., silver image forming) photographic elements in which the underlying (first) emulsion layer is orthochromatically or panchromatically sensitized.
  • the photographic elements can be multicolor photographic elements containing blue recording (yellow dye image forming), green recording (magenta dye image forming) and red recording (cyan dye image forming) layer units in any coating sequence.
  • blue recording yellow dye image forming
  • green recording magenta dye image forming
  • red recording cyan dye image forming
  • Emulsion CC satisfies the requirements of the invention.
  • the remaining emulsions fall outside the scope of the invention.
  • Photographic speeds are reported as relative log speeds, where a speed difference of 30 log units equals a speed difference of 0.3 log E, where E represents exposure in lux-seconds. Contrast is measured as mid-scale contrast.
  • Halide ion concentrations are reported as mole percent (M%), based on silver.
  • a vessel equipped with a stirrer was charged with 6 L of water containing 3.75 g lime-processed bone gelatin, 4.12 g NaBr, an antifoamant, and sufficient sulfuric acid to adjust pH to 1.8, at 39°C.
  • nucleation which was accomplished by balanced simultaneous addition of AgNO 3 and halide (98.5 and 1.5 M% NaBr and KI, respectively) solutions, both at 2.5 M, in sufficient quantity to form 0.01335 mole of silver iodobromide, pBr and pH remained approximately at the values initially set in the reactor solution.
  • the reactor gelatin was quickly oxidized by addition of 128 mg of OxoneTM (2KHSO 5 ⁇ KHSO 4 ⁇ K 2 SO 4 , purchased from Aldrich) in 20 cc of water, and the temperature was raised to 54°C in 9 min. After the reactor and its contents were held at this temperature for 9 min, 100 g of oxidized methionine lime-processed bone gelatin dissolved in 1.5 L H 2 O at 54°C were added to the reactor. Next the pH was raised to 5.90, and 122.5 cc of 1 M NaBr were added to the reactor.
  • OxoneTM 2KHSO 5 ⁇ KHSO 4 ⁇ K 2 SO 4
  • the resulting emulsion was examined by scanning electron micrography (SEM). More than 99.5 % of the total grain project,ed area was accounted for by tabular grains.
  • Emulsion A This emulsion was precipitated exactly as Emulsion A to the point at which 9 moles of silver iodobromide had been formed, then 6 moles of the silver iodobromide emulsion were taken from the reactor. Additional growth was carried out on the 3 moles which were retained in the reactor to serve as seed crystals for further thickness growth. Before initiating this additional growth, 17 grams of oxidized methionine lime-processed bone gelatin in 500 cc water at 54°C was added, and the emulsion pBr was adjusted to ca. 3.3 by the slow addition of AgNO 3 alone until the pBr was about 2.2, followed by an unbalanced flow of AgNO 3 and NaBr.
  • the seed crystals were grown by adding AgNO 3 and a mixed halide salt solution that was 95.875 M% NaBr and 4.125 M% KI until an additional 4.49 moles of silver iodobromide (4.125 M%I) was formed; during this growth period, flow rates were accelerated 2x from start to finish.
  • the resulting emulsion was coagulation washed and stored similarly as Emulsion A.
  • Emulsion A The resulting emulsion was examined similarly as Emulsion A. More than 99.5% of the total grain projected area was provided by tabular grains.
  • the mean ECD of this emulsion was 1.76 ⁇ m, and their COV was 44.
  • a 0.5 mole sample of the emulsion was melted at 40°C and its pBr was adjusted to ca. 4 with a simultaneous addition of AgNO 3 and KI solutions in a ratio such that the small amount of silver halide precipitated during this adjustment was 12% I.
  • the epitaxially sensitized emulsion was split into smaller portions in order to determine optimal levels of subsequently added sensitizing components, and to test effects of level variations.
  • the post-epitaxy components included additional portions of Dyes 1 and 2, 60 mg NaSCN/mole Ag, Na 2 S 2 O 3 .5H 2 O (sulfur), KAuCl 4 (gold), and 11.44 mg 1-(3-acetamidophenyl)-5-mercaptotetrazole (APMT)/mole Ag. After all components were added the mixture was heated to 60°C to complete the sensitization, and after cool-down, 114.4 mg additional APMT was added.
  • the resulting sensitized emulsions were coated on a cellulose acetate film support over a gray silver antihalation layer, and the emulsion layer was overcoated with a 4.3 g/m 2 gelatin layer containing surfactant and 1.75 percent by weight, based on total weight of gelatin, of bis(vinylsulfonyl)methane hardener.
  • Emulsion laydown was 0.646 g Ag/m 2 and this layer also contained 0.323 g/m 2 and 0.019 g/m 2 of Couplers 1 and 2, respectively, 10.5 mg/m 2 of 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene (Na + salt), and 14.4 mg/m 2 2-(2-octadecyl)-5-sulfohydroquinone (Na + salt), surfactant and a total of 1.08 g gelatin/m 2 .
  • Couplers 1 and 2 respectively, 10.5 mg/m 2 of 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene (Na + salt), and 14.4 mg/m 2 2-(2-octadecyl)-5-sulfohydroquinone (Na + salt), surfactant and a total of 1.08 g gelatin/m 2 .
  • the emulsions so coated were given 0.01 sec Wratten 23Aä filtered (wavelengths >560 nm transmitted) daylight balanced light exposures through a calibrated neutral step tablet, and then were developed using the color negative Kodak FlexicolorTM C41 process. Speed was measured at a density of 0.15 above minimum density.
  • This sensitization procedure was similar to that described for epitaxial sensitizations, except that the epitaxial deposition step was omitted.
  • suitable amounts of Dye 1 and Dye 2 were added, then NaSCN, sulfur, gold and APMT were added as before, and this was followed by a heat cycle at 60°C.
  • Tables I and II demonstrate that the speed gain resulting from epitaxial sensitization of an ultrathin tabular grain emulsion is markedly greater than that obtained by a comparable epitaxial sensitization of a thin tabular grain emulsion.
  • Table III further demonstrates that the epitaxially sensitized ultrathin tabular grain emulsion further exhibits a higher contrast than the similarly sensitized thin tabular grain emulsion.
  • This emulsion was prepared in a manner similar to that described for Emulsion A, but with the precipitation procedure modified to provide a higher uniform iodide concentration (AgBr 0.88 I 0.12 ) during growth and a smaller grain size.
  • epitaxial deposition produces stoichiometric related amounts of sodium nitrate as a reaction by-product, which, if left in the emulsion when coated, could cause a haziness that could interfere with optical measurements, these epitaxially treated emulsions were all coagulation washed to remove such salts before they were coated.
  • Emulsion A was sulfur and gold sensitized, with an without epitaxial sensitization, similarly as the emulsions reported in Table II, except that the procedure for optimizing sensitization was varied so that the effect of having slightly more or slightly less spectral sensitizing dye could be judged.
  • a preferred level of spectral sensitizing dye and sulfur and gold sensitizers was arrived at in the following manner: Beginning levels were selected based on prior experience with these and similar emulsions, so that observations began with near optimum sensitizations. Spectral sensitizing dye levels were varied from this condition to pick a workable optimum spectral sensitizing dye level, and sulfur and gold sensitization levels were then optimized for this dye level. The optimized sulfur (Na 2 S 2 O 3 ⁇ 5H 2 O) and gold (KAuCl 4 ) levels were 5 and 1.39 mg/Ag mole, respectively.
  • Emulsion A additionally received an epitaxial sensitization similarly as the epitaxialy sensitized emulsion in Table II.
  • the optimized sulfur (Na 2 S 2 O 3 ⁇ 5H 2 O) and gold (KAuCl 4 ) levels were 2.83 and 0.99 mg/Ag mole, respectively.
  • the results are summarized in Table VIII below: Robustness Tests: Ultrathin Tabular Grain Emulsions Optimally Sulfur and Gold Sensitized With Epitaxy Description Dye 1 mM/Ag M Dye 2 mM/Ag M Rel. Speed Dmin ⁇ Speed Mid Dye 0.444 1.73 100 0.14 check High Dye 0.469 1.83 107 0.15 +7 Low Dye 0.419 1.63 91 0.13 -9
  • Emulsion D (uniform 1.5M% iodide)
  • a vessel equipped with a stirrer was charged with 6 L of water containing 3.75 g lime-processed bone gelatin that had not been treated with oxidizing agent to reduce its methionine content, 4.12 g NaBr, an antifoamant, and sufficient sulfuric acid to adjust pH to 1.8, at 39°C.
  • nucleation which was accomplished by balanced simultaneous 4 sec. addition of AgNO 3 and halide (98.5 and 1.5 mole-% NaBr and KI, respectively) solutions, both at 2.5 M, in sufficient quantity to form 0.01335 mole of silver iodobromide, pBr and pH remained approximately at the values initially set in the reactor solution.
  • the reactor gelatin was quickly oxidized by addition of 128 mg of OxoneTM (2KHSO 5 ⁇ KHSO 4 ⁇ K 2 SO 4 , purchased from Aldrich) in 20 cc H 2 O, and the temperature was raised to 54°C in 9 min. After the reactor and contents were held at this temperature for 9 min, 100 g of oxidized methionine lime-processed bone gelatin dissolved in 1.5 L H 2 O at 54°C were added to the reactor. Next the pH was raised to 5.90, and 122.5 cc of 1 M NaBr were added to the reactor.
  • OxoneTM 2KHSO 5 ⁇ KHSO 4 ⁇ K 2 SO 4
  • the growth stage was begun during which 2.5 M AgNO 3 , 2.8 M NaBr, and a 0.0524 M suspension of AgI were added in proportions to maintain a uniform iodide level of 1.5 mole-% in the growing silver halide crystals, and the reactor pBr at the value resulting from the cited NaBr additions prior to start of nucleation and growth.
  • This pBr was maintained until 0.825 mole of silver iodobromide had formed (constant flow rates for 40 min), at which time the excess Br - concentration was increased by addition of 105 cc of 1 M NaBr, and the reactor pBr was maintained at the resulting value for the balance of grain growth.
  • Emulsion E (uniform 12M% iodide)
  • This emulsion was precipitated by the same procedure employed for Emulsion D, except that the flow rate ratio of AgI to AgNO 3 was increased so that a uniform 12 M% iodide silver iodobromide grain composition resulted, and the flow rates of AgNO 3 and NaBr during growth were decreased such that the growth time was ca. 1.93 times as long, in order to avoid renucleation during growth of this less soluble, higher iodide emulsion.
  • Emulsion E was determined to consist of 98 percent by number tabular grains with tabular grains accounting for more than 99 percent of total grain projected area.
  • Emulsion F (uniform 4.125M% iodide)
  • This emulsion was precipitated by the same procedure employed for Emulsion D, except that the flow rate ratio of AgI to AgNO 3 was increased so that a uniform 4.125 M% iodide silver iodobromide composition resulted, and the flow rates of AgNO 3 and NaBr during growth were decreased such that the growth time was ca. 1.20 times as long, in order to avoid renucleation during growth of this less soluble, higher iodide emulsion.
  • Emulsion E was determined to consist of 97.8 percent by number tabular grains with tabular grains accounting for greater than 99 percent of total grain projected area.
  • Emulsion G profiled iodide
  • This emulsion was precipitated by the same procedure employed for Emulsion D, except that after 6.75 moles of emulsion (amounting to 75 percent of total silver) had formed containing 1.5 M% I silver iodobromide grains, the ratio of AgI to AgNO 3 additions was increased so that the remaining portion of the 9 mole batch was 12 M% I.
  • flow rate based on rate of total Ag delivered to the reactor, was approximately 25% that employed in forming Emulsion D, (total growth time was 1.19 times as long) in order to avoid renucleation during formation of this less soluble, higher iodide composition.
  • Emulsion G was determined to consist of 97 percent by number tabular grains with tabular grains accounting for greater than 99 percent of total grain projected area.
  • Emulsion Grain Size and Halide Data Emulsion Iodide in AgIBr Grains ECD ( ⁇ m) Thickness ( ⁇ m) Aspect Ratio D 1.5 M% I (uniform) 1.98 0.055 36.0 E 12.0 M% I (uniform) 1.60 0.086 18.6 F 4.125 M% I (uniform) 1.89 0.053 35.7 G 1.5 M% I (1st 75% Ag) 1.67 0.056 29.8 12 M% I (last 25% Ag)
  • Emulsion G contained grains dimensionally comparable to those of Emulsions D and F, containing uniformly distributed 1.5 or 4.125 M% iodide concentrations, respectively.
  • Emulsion E which contained 12.0 M% iodide uniformly distributed within the grains showed a loss in mean ECD, an increase in mean grain thickness, and a reduction in the average aspect ratio of the grains.
  • Samples of the emulsions were next similarly sensitized to provide silver salt epitaxy selectively at corner sites on the tabular grains of Emulsions D, E, F and G.
  • the epitaxially sensitized emulsion was split into smaller portions to determine optimal levels of subsequently added sensitizing components, and to test effects of level variations.
  • the post-epitaxy components included additional portions of Dyes 1 and 2, 60 mg NaSCN/mole Ag, Na 2 S 2 O 3 .5H 2 O (sulfur), KAuCl 4 (gold), and 11.44 mg APMT/mole Ag. After all components were added, the mixture was heated to 60°C to complete the sensitization, and after cooling to 40°C, 114.4 mg additional APMT were added.
  • the resulting sensitized emulsions were coated on cellulose acetate support over a gray silver antihalation layer, and the emulsion layer was overcoated with a 4.3 g/m 2 gelatin layer.
  • Emulsion laydown was 0.646 g Ag/m 2 and this layer also contained 0.323 g/m 2 and 0.019 g/m 2 of Couplers 1 and 2, respectively, 10.5 mg/m 2 of 4-hydroxy-6-methyl-1,3,3A,7-tetraazaindene (Na + salt), and 14.4 mg/m 2 2-(2-octadecyl)-5-sulfohydroquinone (Na + salt), and a total of 1.08 g gelatin/m 2 .
  • the emulsion layer was overcoated with a 4.3 g/m 2 gelatin layer containing surfactant and 1.75 percent by weight, based on the total weight of gelatin, of bis(vinylsulfonyl)methane hardener.
  • the emulsions so coated were given 0.01" Wratten 23Aä filtered daylight balanced light exposures through a 21 step granularity step tablet (0-3 density range), and then were developed using the Kodak FlexicolorTM C41 color negative process. Speed was measured at a density of 0.30 above D min .
  • Granularity readings on the same processed strips were made according to procedures described in the SPSE Handbook of Photographic Science and Engineering, edited by W. Thomas, pp. 934-939. Granularity readings at each step were divided by the contrast at the same step, and the minimum contrast normalized granularity reading was recorded. Contrast normalized granularity is reported in grain units (g.u.), in which each g.u. represents a 5% change; positive and negative changes corresponding to grainier and less grainy images, respectively (i.e., negative changes are desirable). Contrast-normalized granularities were chosen for comparison to eliminate granularity differences attributable to contrast differences.
  • Emulsion H Profiled iodide, AgBr Central Region
  • Emulsions D-G This emulsion was precipitated similarly as Emulsions D-G, but with the significant difference of lowered iodide concentrations in the central regions of the ultrathin tabular grains.
  • the absence of iodide in the central region was of key importance, since, in the absence of an adsorbed site director, the portions of the major faces of the ultrathin tabular grains formed by the central region accepts silver salt epitaxy. Therefore this structure was chosen to allow comparison of central region and laterally displaced region (specifically, corner) epitaxial sensitizations, which can be formed in the absence or presence, respectively, of one or more adsorbed site directors.
  • the first 75 percent of the silver was precipitated in the absence of iodide while the final 25 percent of the silver was precipitated in the presence of 6 M% I.
  • Emulsion H was found to consist of 98 percent tabular grains, which accounted for greater than 99 percent of total grain projected area.
  • Emulsion H/CR Central Region Epitaxial Sensitization
  • Emulsion H/LDR (Laterally Displaced Region Epitaxial Sensitization)
  • Emulsion H/CR is 51 speed units faster than Emulsion H/LDR, with only a 3 g.u. penalty. This is a highly favorable speed/granularity trade; from previous discussion it is evident that the random dot model predicts ca. 11.9 g.u. increase as a penalty accompanying the 0.51 log E speed increase at constant Ag laydown, assuming an invariant photoefficiency.
  • corner epitaxy sensitization of the profiled iodide ultrathin tabular grain emulsions of the invention offers a large speed-granularity (photoefficiency) advantage over the same profiled iodide ultrathin tabular gain emulsions, but with the silver salt epitaxy distributed over the major faces of the grains.
  • the improved photoefficiency of the emulsions of the invention is not only a function of the iodide profiling selected, but also a function of the silver salt epitaxy and its location.
  • Emulsion C was dyed with 1715 mg of Dye 2 per Ag mole, then emulsion pBr was adjusted to 4.0 with AgNO 3 and KI added in relative rates so that the small amount of silver halide formed corresponded to the original composition AgI 0.12 Br 0.88 .
  • Silver halide epitaxy amounting to 12 mole percent of silver contained in the host tabular grains was then precipitated.
  • Halide and silver salt solutions were added in sequence with a two mole percent excess of the chloride salt being maintained to assure precipitation of AgCl.
  • Silver and halide additions are reported below based on mole percentages of silver in the host tabular grains.
  • the rate of AgNO 3 addition was regulated to precipitate epitaxy at the rate of 6 mole percent per minute.
  • Sensitization C-1 14 M % NaCl was added followed by 12 M % AgNO 3 for a nominal (input) epitaxy composition of 12 M % AgCl.
  • Sensitization C-2 12.08 M % NaCl was added followed by 1.92 M % AgI (Lippmann) followed in turn by 10.08 M % AgNO 3 for a nominal (input) epitaxy composition of 12 M % AgI 0.16 Cl 0.84 .
  • Sensitization C-3 7.04 M % NaCl was added followed by 5.04 M % NaBr followed in turn by 1.92 M % AgI (Lippmann) followed in turn by 10.08 M % AgNO 3 for a nominal composition of 12 M % AgI 0.16 Br 0.42 Cl 0.42 .
  • the separately sensitized samples were subjected to chemical sensitization finishing conditions, but sulfur and gold sensitizers were withheld to avoid complicating halide analysis of the epitaxial protrusions. Finishing consisted of adding 60 mg of NaSCN and 11.4 mg of APMT per Ag mole. These additions were followed by heating the mixture to 50°C, followed by the addition of 114.4 mg of APMT per silver mole.
  • Analytical electron microscopy (AEM) techniques were then employed to determine the actual as opposed to nominal (input) compositions of the silver halide epitaxial protrusions.
  • the general procedure for AEM is described by J. I. Goldstein and D. B. Williams, "X-ray Analysis in the TEM/STEM", Scanning Electron Microscopy/1977 ; Vol. 1, IIT Research Institute, March 1977, p. 651.
  • the composition of an individual epitaxial protrusion was determined by focusing an electron beam to a size small enough to irradiate only the protrusion being examined.
  • the selective location of the epitaxial protrusions at the corners of the host tabular grains facilitated addressing only the epitaxial protrusions.
  • the minimum AEM detection limit was a halide concentration of 0.5 M %.
  • the emulsion prepared was a silver iodobromide emulsion containing 4.125 M % I, based on total silver.
  • a vessel equipped with a stirrer was charged with 9.375 L of water containing 30.0 grams of phthalic anhydride-treated gelatin (10% by weight) 3.60 g NaBr, an antifoamant, and sufficient sulfuric acid to adjust pH to 2.0 at 60°C.
  • phthalic anhydride-treated gelatin 10% by weight
  • 3.60 g NaBr 3.60 g NaBr
  • an antifoamant 3.60 g
  • sulfuric acid to adjust pH to 2.0 at 60°C.
  • nucleation which was accomplished by an unbalanced simultaneous 30 sec. addition of AgNO 3 and halide (0.090 mole AgNO 3 , 0.1095 mole NaBr, and 0.0081 mole KI) solutions, during which time reactor pBr decreased due to excess NaBr that was added during nucleation, and pH remained approximately constant relative to values initially set in the reactor solution.
  • the reactor gelatin was quickly oxidized by addition of 1021 mg of OxoneTM(2KHSO 5 .KHSO 4 .K 2 SO 4 , purchased from Aldrich) in 50 cc H 2 O. After the reactor and contents were held at this temperature for 7 min, 100 g of oxidized methionine lime-processed bone gelatin dissolved in 1.5 L H 2 O at 54°C was added to the reactor. Next the pH was raised to 5.90, and 12 min after completing nucleation, 196.0 cc of 1 M NaBr were added to the reactor.
  • the post-epitaxy components included 0.14 mg bis(2-amino-5-iodopyridinedihydroiodide) mercuric iodide, 137 mg Dye 4, 12.4 mg Dye 6, 60 mg NaSCN, 6.4 mg Sensitizer 1 (sulfur), 3 mg Sensitizer 2 (gold), and 11.4 mg APMT.
  • the coating support was a 132 ⁇ m thick cellulose acetate film support that had a rem jet antihalation backing and a gelatin subbing layer (4.89 g/m 2 ), and the emulsion layer was overcoated with a 4.3 g/m 2 gelatin layer which also contained surfactant and 1.75 percent by weight, based on total gelatin, of bis(vinylsulfonyl)methane hardener.
  • Emulsion laydown was 0.538 g Ag/m 2 and this layer also contained 0.398 g/m 2 and 0.022 g/m 2 of Couplers 3 and 4, respectively, 8.72 mg/m2 of 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene (Na + salt), and 11.96 mg/m 2 2-(2-octadecyl)-5-sulfohydroquinone (Na + salt), surfactant and a total of 1.08 g gelatin/m 2 .
  • the emulsions so coated were given 0.01" Wratten 9ä filtered (>460 nm)daylight balanced light exposures through a 21 step granularity step tablet (0-3 density range), and then were developed using the Kodak FlexicolorTM C41 color negative process. Speed was measured at 0.15 above minimum density. Granularity readings on the same processed strips were made as described for Emulsions D through G.
  • Sensitization D-1 The sensitization, coating and evaluation procedures were the same as for Sensitization D-1, except that the halide salt solution for double jet formation of epitaxy was 92 M % Cl added as NaCl and 8 M % I added as KI.
  • the emulsion prepared was a silver iodobromide emulsion containing 4.125 M % I, based on total silver.
  • a central region of the grains accounting for 75 % of total silver contained 1.5 M % I while a laterally displaced region accounting for the last 25 % of total silver precipitated contained 12 M % I.
  • a vessel equipped with a stirrer was charged with 6 L of water containing 3.75 g lime-processed bone gelatin, 4.12 g NaBr, an antifoamant, and sufficient sulfuric acid to adjust pH to 1.86, at 39°C.
  • nucleation which was accomplished by balanced simultaneous 4 sec. addition of AgNO 3 and halide (98.5 and 1.5 M % NaBr and KI, respectively) solutions, both at 2.5 M, in sufficient quantity to form 0.01335 mole of silver iodobromide, pBr and pH remained approximately at the values initially set in the reactor solution.
  • the reactor gelatin methionine was quickly oxidized by addition of 128 mg of OxoneTM (2KHSO 5 .KHSO 4 .K 2 SO 4 , purchased from Aldrich) in 50 cc H 2 O, and the temperature was raised to 54°C in 9 min. After the reactor and contents were held at this temperature for 9 min, 100 g of oxidized methionine lime-processed bone gelatin dissolved in 0.5 L H 2 O at 54°C were added to the reactor. Next the pH was raised to 5.87, and 107.0 cc of 1 M NaBr were added to the reactor.
  • the growth stage was begun during which 1.6 M AgNO 3 , 1.75 M NaBr and a 0.0222 M suspension of AgI (Lippmann) were added in proportions to maintain a uniform iodide level of 1.5 M % in the growing silver halide crystals, and the reactor pBr at the value resulting from the cited NaBr additions prior to start of nucleation and growth.
  • This pBr was maintained until 0.825 mole of silver iodobromide had formed (constant flow rates for 40 min), at which time the excess Br - concentration was increased by addition of 75 cc of 1.75 M NaBr, the reactor pBr being maintained at the resulting value for the balance of the growth.
  • the flow rate of AgNO 3 was accelerated to approximately 8.0 times its starting value during the next 41.3 min of growth. After 4.50 moles of emulsion had formed (1.5 M % I), the ratio of flows of AgI to AgNO 3 was changed such that the remaining portion of the 6 mole batch was 12 M % I. At the start of the formation of this high iodide band, the flow rate, based on rate of total Ag delivered to the reactor, was initially decreased to approximately 25% of the value at the end of the preceding segment in order to avoid renucleation during formation of this less soluble, higher iodide band, but the flow rate was doubled from start to finish of the portion of the run. When addition of AgNO 3 , AgI and NaBr was complete, the resulting emulsion was coagulation washed and pH and pBr were adjusted to storage values of 6 and 2.5, respectively.
  • Emulsion J A 0.5 mole sample of Emulsion J was melted at 40°C, and its pBr was adjusted to ca. 4 by simultaneous addition of AgNO 3 and KI solutions in a ratio such that the small amount of silver halide precipitated during this adjustment was 12 M % I.
  • sensitizers This allowed variations in levels of sensitizers in order to determine optimum treatment combinations.
  • the post-epitaxy components included Dye 4, Dye 6 and Dye 7, 60 mg NaSCN/mole Ag, Sensitizer 1 (sulfur), Sensitizer 2 (gold), and 8.0 mg N-methylbenzothiazolium iodide. After all components were added, the mixture was heated to 50°C for 5 min to complete the sensitization, and after cooling to 40°C, 114.35 mg additional APMT was added.
  • the emulsion prepared was a silver iodobromide emulsion containing 4.125 M % I, based on total silver.
  • a central region of the grains accounting for 74 % of total silver contained 1.5 M % I while a laterally displaced region accounting for the last 26 % of total silver precipitated contained 12 M % I.
  • a vessel equipped with a stirrer was charged with 6 L of water containing 3.75 g lime-processed bone gelatin, 4.12 g NaBr, an antifoamant, and sufficient sulfuric acid to adjust pH to 5.41, at 39°C.
  • nucleation which was accomplished by balanced simultaneous 4 sec. addition of AgNO 3 and halide (98.5 and 1.5 M % NaBr and KI, respectively) solutions, both at 2.5 M, in sufficient quantity to form 0.01335 mole of silver iodobromide, pBr and pH remained approximately at the values initially set in the reactor solution.
  • the methionine in the reactor gelatin was quickly oxidized by addition of 0.656 cc of a solution that was 4.74 M % NaOCl, and the temperature was raised to 54°C in 9 min. After the reactor and contents were held at this temperature for 9 min, 100 g of oxidized methionine lime-processed bone gelatin dissolved in 1.5 L H 2 O at 54°C, and 122.5 cc of 1 M NaBr were added to it (after which pH was ca. 5.74).
  • the growth stage was begun during which 2.50 M AgNO 3 , 2.80 M NaBr, and a 0.0397 M suspension of AgI (Lippmann) were added in proportions to maintain a uniform iodide level of 1.5 M % in the growing silver halide crystals, and the reactor pBr at the value resulting from the cited NaBr additions prior to the start of nucleation and growth.
  • 2.50 M AgNO 3 , 2.80 M NaBr, and a 0.0397 M suspension of AgI (Lippmann) were added in proportions to maintain a uniform iodide level of 1.5 M % in the growing silver halide crystals, and the reactor pBr at the value resulting from the cited NaBr additions prior to the start of nucleation and growth.
  • growth reactant flow rate based on rate of total Ag delivered to the reactor, was initially decreased to approximately 25% of the value at the end of the preceding segment in order to avoid renucleation during formation of this less soluble, higher iodide composition band, but it was accelerated (end flow 1.6 times that at the start of this segment) during formation of this part of the emulsion.
  • end flow 1.6 times that at the start of this segment
  • the resulting emulsion was coagulation washed and pH and pBr were adjusted to storage values of 6 and 2.5, respectively.
  • Emulsion K A 0.5 mole sample of Emulsion K was melted at 40°C and its pBr was adjusted to ca. 4 by simultaneous addition of AgNO 3 and KI solutions in a ratio such that the small amount of silver halide precipitated during this adjustment was 12 M % I.
  • 2 M % NaCl (based on the original amount of silver in the Emulsion F sample) was added, followed by addition of Dye 4 and Dye 6 (1173 and 106 mg/mole Ag, respectively), after which 6 mole-% epitaxy was formed as follows: A single-jet addition of 6 M % NaCl, based on the original amount of host emulsion, was made, and this was followed by a single-jet addition of 6 M % AgNO 3 .
  • the AgNO 3 addition was made in 1 min.
  • the post-epitaxy components added were 60 mg NaSCN/mole Ag, Na 2 S 2 O 3 .5H 2 O (sulfur sensitizer) and KAuCl 4 (gold sensitizer), and 3.99 mg 3-methyl-1,3-benzothiazolium iodide/mole Ag.
  • Sulfur and gold sensitizer levels were the best obtained from several trial sensitizations. After all components were added, the mixture was heated to 60°C for 8 min to complete the sensitization. After cooling to 40°C, 114.35 mg APMT/mole Ag were added. The optimum sensitization was 2.9 mg/M Ag Na 2 S 2 O 3 .5H 2 O and 1.10 mg/M Ag KAuCl 4 .
  • Coupler 5 (0.323 g/m 2 ) was substituted for Coupler 3, and the laydown of Coupler 2 was 0.016 g/m 2 .
  • the procedure was identical to Sensitization K-1, except that instead of the sequential single jet additions of 6 M % NaCl and 6 M % AgNO 3 the following were added sequentially: 2.52 M % NaCl, 2.52 M % NaBr, 0.96 M % AgI (Lippmann) and 5.04 M % AgNO 3 .
  • the percentages are based on silver provided by Emulsion K.
  • the optimum sensitization was 2.3 mg/M Ag Na 2 S 2 O 3 .5H 2 O and 0.80 mg/M Ag KAuCl 4 .
  • Emulsions AA and BB demonstrate that adding both a SET dopant and an iridium dopant to the host tabular grain portion of an epitaxially sensitized ultrathin tabular grain emulsion largely, if not entirely, eliminates the ability of the iridium dopant to reduce high intensity reciprocity failure (HIRF).
  • Emulsion CC demonstrates that shifting the SET dopant to the epitaxy while leaving the iridium dopant in the ultrathin tabular grains results in an even higher speed while restoring the effectiveness of the iridium dopant in reducing HIRF.
  • a reaction vessel equipped with a stirrer was charged with 6 L of water containing 3.75 g of lime-processed bone gelatin, 4.12 g NaBr, an antifoamant and sufficient sulfuric acid to adjust pH to 5.42 at 39°C.
  • Nucleation was accomplished by a balanced simultaneous 4 second addition of 2.5 M AgNO 3 and 2.5 M halide (98.5 M % Br and 1.5 M % I, added as NaBr and KI, respectively) solutions in an amount sufficient to form 0.01335 mole of silver iodobromide. Both pBr and pH remained at or near the values initially set in the reaction vessel.
  • the methionine portion of the gelatin in the reaction vessel was oxidized by the introduction of 50 cc of a 0.062 percent by weight solution of NaOCl, and the temperature within the reaction vessel was raised to 54°C in 9 minutes. After holding at this temperature for 9 minutes, 100 g of oxidized methionine lime-processed bone gelatin dissolved in 1.5 L H 2 O at 54°C were added to the reaction vessel.
  • the flow rate of AgNO 3 was accelerated during the next 52.5 min, so that end flow was about 10 times greater than at the start of this segment, by which time 6.75 moles AgBr 0.985 I 0.015 had formed.
  • flow rates of AgNO 3 , AgI and NaBr were continued, but with a more concentrated (0.341 M) suspension of AgI, and with a reduced initial flow rate of 2.5 M AgNO 3 (0.25 times as great as at the end of the 1.5 M % I growth).
  • the AgNO 3 flow rate was accelerated so that the final flow rate was 1.6 times that at the start.
  • the relative flow rates of AgNO 3 , AgI and NaBr were modulated so as to maintain the pBr from the previous growth segment and to achieve an iodide concentration 12 M %, based on silver, during precipitation of the final 2.25 moles of silver.
  • the emulsion was cooled to 40°C and coagulation washed. pH and pBr were then adjusted to storage values of 6 and 2.5, respectively.
  • Emulsion M (graded iodide host tabular grains)
  • a reaction vessel equipped with a stirrer was charged with 6.75 L of water containing 4.21 g of lime-processed bone gelatin, 4.63 g NaBr, an antifoamant and sufficient sulfuric acid to adjust pH to 1.77 at 39°C.
  • Nucleation was accomplished by a balanced simultaneous 4 second addition of 2.4 M AgNO 3 and 2.4 M halide (98.5 M % Br and 1.5 M % I, added as NaBr and KI, respectively) solutions in an amount sufficient to form 0.0150 mole of silver iodobromide. Both pBr and pH remained at or near the values initially set in the reaction vessel.
  • the methionine portion of the gelatin in the reaction vessel was oxidized by the introduction of 50 cc of a 0.07 percent by weight solution of NaOCl, and the temperature within the reaction vessel was raised to 54°C in 9 minutes. After holding at this temperature for 6 minutes, 100 g of oxidized methionine lime-processed bone gelatin dissolved in 1.5 L H 2 O (also containing 0.165 mole of NaOH) at 54°C were added to the reaction vessel, followed by a pH adjustment to 5.85. Twenty four and four tenths minutes after nucleation 333.6 cc of a 1 M halide solution (33 M % NaBr and 67 M % NaCl) were added to the reaction vessel.
  • the emulsion was cooled to 40°C and coagulation washed. pH and pBr were then adjusted to storage values of 6 and 2.5, respectively.
  • the resulting tabular grain silver iodobromide emulsion contained an iodide concentration of 4.125 M % in the first 75 percent of the grain to precipitate and 12 M % in the last 25 percent of the grain to precipitate. Grain characteristics were measured as reported for Emulsion A. Greater than 99 percent of total grain projected area was accounted for by tabular grains. The mean ECD of the grains was 1.79 ⁇ m. The mean thickness of the tabular grains was 0.056 ⁇ m.
  • a 0.5 mole sample of the emulsion was melted at 40°C and its pBr was adjusted to ca. 4 with a simultaneous addition of AgNO 3 and KI solutions in a ratio such that the small amount of silver halide precipitated during this adjustment was 12% I.
  • Dye 1 and anhydro-5,5'-dichloro-9-ethyl-3,3'-bis(2-hydroxy-3-sulfopropyl)thiacarbocyanine hydroxide, triethylammonium salt, Dye 8 were used, and for green sensitizations Dyes 3 and 4 were used.
  • the epitaxially sensitized emulsion samples were split into smaller portions to determine optimal levels of subsequently added sensitizing components.
  • the post-epitaxy components included 0.75 mg 4,4'-phenyl disulfide diacetanilide, additional portions of the same sensitizing dyes previously employed, 60 mg NaSCN/Ag mole, Sensitizer 1 (sulfur sensitizer), Sensitizer 2 (gold sensitizer), 5.72 mg APMT/Ag mole (red sensitized emulsions only), and 3.99 mg 3-methyl-1,3-benzothiazolium iodide/Ag mole (green sensitized emulsions only). After all post-epitaxy sensitizing components were added, the mixture was heated to 50°C for 5 minutes to complete the sensitization. After cooling to 40°C, an additional 114.35 mg AMPT/Ag mole were added.
  • the red sensitized emulsions were coated on a cellulose acetate film support over a gray silver antihalation layer.
  • the green sensitized emulsions were coated on a similar support, with a 4.89 g gelatin/m 2 subbing layer and, instead of the gray silver antihalation layer, the support carried a rem jet antihalation layer on its back side.
  • Emulsion laydown was 0.646 and 0.538 g Ag/m 2 for the red and green sensitized emulsions, respectively.
  • Each emulsion layer contained, surfactant, 1.75 g/Ag mole 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene (Na + salt) and 2.40 g/Ag mole 2-(2-octadecyl)-5-sulfohydro-quinone (Na + salt), dye-forming couplers, and a total of 1.08 g gelatin/m 2 .
  • Couplers 1 and 2 were used at 0.323 and 0.019 g/m 2 , respectively.
  • Couplers 4 and 5 were used at 0.016 and 0.323 g/m 2 , respectively.
  • Each emulsion layer was overcoated with a 4.3 g/m 2 gelatin layer that contained surfactant and 1.75 weight percent, based on total gelatin coated, of bis(vinylsulfonyl)methane hardener.
  • the emulsions were given a 0.01 sec exposure balanced daylight exposure.
  • the red sensitized coatings were exposed through a WrattenTM 23A (>560 nm transmission) filter, and the green sensitized coatings were exposed through a WrattenTM 9 (>460 nm transmission) filter.
  • the exposures were taken through a 21 step granularity step tablet (0-3 density range), and then were developed using the Kodak FlexicolorTM C41 color negative process. Speed was measured at 0.15 above minimum density. Granularity readings on the same processed strips were made as described for Emulsions D through G.
  • Samples of Emulsion L were selected as being representative of emulsions according to the invention optimally sensitized to the red region of the spectrum. Each sample contained, per mole of Ag, 223 mg of Dye 1, 961 mg of Dye 8, 2.25 mg of the sulfur sensitizer and 0.79 mg of the gold sensitizer. Samples differing solely by the presence or absence of 30 mppm K 4 Ru(CN) 6 per mole of host emulsion present during epitaxial deposition are compared in Table XVI below. The addition of the dopant did not affect the thickness of the tabular grains, nor did it have any effect on granularity. Effect of Shallow Electron Traps in Epitaxy of Green Sensitized Ultrathin Tabular Grain Emulsion SET-2 mppm Relative Log Speed Dmin 0 100 0.15 30 111 0.18
  • Emulsion M Samples of Emulsion M were selected as being representative of ultrathin tabular grain emulsions spectrum. Each sample contained, per mole of Ag, 336 mg of Dye 3, 973 mg of Dye 4, 2.30 mg of the sulfur sensitizer and 0.84 mg of the gold sensitizer. Samples differing solely by the presence or absence of 30 mppm K 4 Ru(CN) 6 per mole of host emulsion Ag during epitaxial deposition are compared in Table XVII below. The addition of the dopant did not affect the thickness of the tabular grains, nor did it have any affect on granularity. Effect of Shallow Electron Traps in Epitaxy of Red Sensitized Ultrathin Tabular Grain Emulsion SET-2 mppm Relative Log Speed Dmin 0 100 0.06 30 109 0.06
  • Aqueous solutions of 2.38 M AgNO 3 and 2.38 M Na(Br 0.95 I 0.05 ) were introduced at 50°C over 0.25 minute each at 105.6 mL/min in a double-jet mode into 6.56 L of 0.0048 M NaBr solution containing 3.84 g/L of oxidized methionine lime processed bone gelatin, an antifoamant and sufficient H 2 SO 4 to adjust the solution pH to a value of 2.0.
  • more oxidized methionine gelatin (70 g) was added in a basic aqueous solution such that the pH increased to 6.0 (at 50°C) after this addition.
  • the first 20.33 minutes of precipitation were carried out with a gradation of the pBr from 1.95 to 1.7. pBr was thereafter maintained constant.
  • the first 59.83 minutes of precipitation (accounting for 75 percent of total silver) was accomplished using a AgNO 3 flow rate linear ramp of from 11.0 to 76.8 mL/min.
  • the silver nitrate flow rate was ramped from 16.3 to 47.3 mL/min over 27.23 minutes, and the Lippmann addition rate was adjusted to maintain a nominal 12 M % iodide concentration, based on silver.
  • the emulsion was subsequently washed via ultrafiltration, and the pH and pBr were adjusted to storage values of 6.0 and 3.4, respectively.
  • Emulsion O (iodide banded, Ir doped)
  • Emulsion N The preparation of Emulsion N was repeated, except that after 70 percent of total silver had been introduced and without interrupting the additions of silver and halides K 2 IrCl 6 was introduced in an aqueous solution in the amount of 0.05 mg per mole of total silver forming the emulsion.
  • Emulsions N and O were identically sensitized in the following manner: A 1 mole sample of the emulsion was heated to 40°C, and its pBr adjusted to about 4 with a simultaneous addition of AgNO 3 and KI (mole ratio 1:0.12). Then 2 M % NaCl based on silver present before the above pBr adjustment was added. Red spectral tral sensitizing dyes, Dye 1 and Dye 8 were then added in an overall molar concentration of 1.9 mmol/M Ag (molar ratio Dye 1:Dye 8 1:4). Next silver salt epitaxy was deposited in the amount of 6 mole percent, based on the silver forming the tabular grains.
  • the epitaxially sensitized emulsion was next divided into smaller portions with the aim of establishing optimal levels of chemical sensitization.
  • To each sample were added 60 mg/Ag mole NaSCN, Sensitizer 1 as a sulfur sensitizer, Sensitizer 2 as a gold sensitizer, 8 mg/Ag mole APMT and 2.25 mg/Ag mole of bis( p -acetamidophenyl)disulfide.
  • the emulsion with the sensitizers added was heated to 55°C for 25 minutes. After cooling to 40°C, 114.4 mg of additional APMT was added. From varied levels of Sensitizers 1 and 2 the optimal sensitization was identified and is the basis of the observations below.
  • the resulting sensitized emulsions were coated on a cellulose acetate film support over a gray silver antihalation layer, and the emulsion was overcoated with a 1.076 g/m 2 gelatin layer containing surfactant and 1.75 percent by weight, based on total weight of gelatin, of bis(vinylsulfonyl)methane hardener.
  • Emulsion laydown was 0.646 g Ag/m 2 and the emulsion layer also contained 0.646 g/m 2 of Coupler 1 and 0.21 g/m 2 of Coupler 2, along with 5.65 mg/m 2 of 5-bromo-4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene triethylammonium salt and surfactant.
  • Total gelatin amounted to 2.15 g/m 2 .
  • Emulsions N and 0 were exposed and processed similarly as Emulsion A, except that different samples also received exposures ranging from 10 -5 to 1 second to allow reciprocity failure to be examined.
  • Table XVIII the differences in observed speed for 10 -5 and 10 -1 second exposures are reported at densities of 0.15, 0.35, 0.55, 0.75, 0.95 and 1.15 above minimum density. Negative values indicate lower speed for the shorter duration exposure, which is indicates high intensity reciprocity failure.
  • the same exposure value (I X t, where I is exposure intensity and t is exposure time) should result in the same speed with varied selections of I and t.
  • a speed change ( ⁇ log E) of zero represents a photographic ideal (no reciprocity law failure).
  • Emulsion P (no dopant)
  • a silver iodobromide (2.6 M % I, uniformly distributed) emulsion was precipitated by a procedure similar to that employed by Antoniades et al for precipitation of Emulsions TE-4 to TE-11. Greater than 99 percent of total grain projected area was accounted for by tabular grains.
  • the mean ECD of the grains was 2.45 ⁇ m and the mean thickness of the grains was 0.051 ⁇ m. The average aspect ratio of the grains was 48. No dopant was introduced during the precipitation of this emulsion.
  • Emulsion S A series of emulsions were prepared similarly as Emulsion P, except that a dopant was incorporated in the ultrathin tabular grains following nucleation over an extended interval of grain growth to minimize thickening of the tabular grains. Attempts to introduce dopant into the reaction vessel prior to nucleation resulted in thickening of the ultrathin tabular grains and, at higher dopant concentrations, formation of tabular grains which were greater than 0.07 ⁇ m in thickness. All of the emulsions, except Emulsion S, contained the same iodide content and profile as Emulsion P. Emulsion S was precipitated by introducing no iodide in the interval from 0.2 to 55 percent of silver addition and by introducing iodide at a 2.6 M % concentration for the remainder of the precipitation.
  • the results are summarized in Table XIX.
  • the concentrations of the dopants are reported in terms of molar parts of dopant added per million molar parts of Ag (mppm).
  • the Profile % refers to the interval of dopant introduction, referenced to the percent of total silver present in the reaction vessel at the start and finish of dopant introduction. Emul. Total Dopant mppm Local Dopant Conc. mppm Dopant Profile % Grain Thickness ⁇ m Av.
  • Emulsions P through Z were identically chemically and spectrally sensitized as follows: 150 mg/Ag mole NaSCN, 2.1 mmole/Ag mole of Dye 2, 20 ⁇ mole/Ag mole Sensitizer 1 and 6.7 ⁇ mole Sensitizer 2 were added to the emulsion. The emulsion was then subjected to a heat digestion at 65°C for 15 minutes, followed by that addition of 0.45 M % KI and AgNO 3 .
  • Samples of the sensitized emulsions were then coated as follows: 0.538 g Ag/m 2 , 2.152 g/m 2 gelatin (half from original emulsion and half added), 0.968 g/m 2 Coupler 1 and 1 g/Ag mole 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene (Na + salt).
  • the emulsion layer was overcoated with 1.62 g/m 2 gelatin and 1.75 weight percent bis(vinylsulfonyl)methane, based on total gelatin in the emulsion and overcoat layers.
  • Aqueous solutions of 2.5 M AgNO 3 and 2.5 M Na(Br 0.95 I 0.05 ) were each introduced over 15 seconds each at 101.2 mL/min by double jet addition into a stirred reaction vessel at 50°C containing 6.00 L of 0.0056 M NaBr solution containing 2.54 g/L of oxidized lime processed bone gelatin, an antifoamant and sufficient H 2 SO 4 to adjust the solution pH to a value of 2.0.
  • more oxidized gelatin 95.36 g was added in a basic aqueous solution such that the pH increased to 6.0 (at 50°C) after this addition.
  • the first 20.33 min portion of the inner region growth was carried out with a gradation of the pBr from 1.95 to 1.7. Thereafter pBr was maintained constant. After 70 percent of total silver had been precipitated, 0.01 mg/Ag mol (0.2 mppm) of K 2 IrCl 6 was added within 10 seconds in a dilute aqueous solution and 30 seconds later 24.8 mg/Ag mol (57 mppm) K 4 Ru(CN) 6 (SET-2) was added within 10 seconds in a dilute aqueous solution. Both dopant concentrations are based on total silver forming the tabular grains. During these dopant additions the other reactant introductions were not interrupted.
  • the resulting silver iodobromide emulsion contained 4.5 M% iodide and tabular grains accounting for greater than 90 percent of total grain projected area.
  • the mean ECD of the emulsion grains was 1.44 ⁇ m, and the mean thickness of the tabular grains was 0.048 ⁇ m.
  • Emulsion BB Emulsion BB
  • This emulsion was prepared identically to Emulsion AA, except that the concentration of SET-2 was increased to 82.7 mg/Ag mole (190 mppm) based on tabular grain emulsion silver.
  • the grains were similar to those of Emulsion AA, except that mean ECD was 1.42 ⁇ m.
  • This emulsion was prepared identically to Emulsion AA, except that SET-2 was omitted from the precipitation.
  • the grains were similar to those of Emulsion AA, except that mean ECD was 1.49 ⁇ m and mean grain thickness was 0.051 ⁇ m.
  • Emulsions AA, BB and CC were identically epitaxially sensitized, except that the dopant K 4 Ru(CN) 6 (SET-2) was added with the epitaxy in the sensitization of Emulsion CC in the amount of 24.8 mg/Ag mole (57 mppm) based on silver in the host emulsion.
  • the dopant K 4 Ru(CN) 6 SET-2
  • the epitaxially sensitized emulsions were each divided into smaller portions to determine optimal levels of subsequently added sensitizing components. To these components were added additional portions of Dyes 1 and 2, 60 mg NaSCN/mole Ag, sulfur Sensitizer 1, gold Sensitizer 2, 8 mg APMT/mole Ag, 2.25 mg/Ag mole of 4,4'-phenyl disulfide diacetamide, and 1.97 g/Ag mole 3,5-disulfocatechol. After all components were added the mixture was heated to 52, 55 and 58°C for 15, 25 or 35 minutes, respectively, to complete the sensitization. After cool-down, 114.4 mg additional APMT was added.
  • the optimally sensitized emulsions were coated on a cellulose acetate film support over a gray silver antihalation layer, and the emulsion layer was overcoated with a 1.076 g/m 2 gelatin layer containing surfactant and 1.75 percent by weight, based on total weight of gelatin, of bis(vinylsulfonyl)methane hardener.
  • Emulsion laydown was 0.646 g Ag/m 2 and this layer also contained 0.646 g/m 2 and 0.021 g/m 2 of Couplers 1 and 2, respectively, 5.65 mg/m 2 of 5-bromo-4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene triethylammonium (TEA) salt, surfactant and a total of 2.15 g gelatin/m 2 .
  • TAA 5-bromo-4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene triethylammonium
  • the emulsions so coated were given Wratten 23Aä filtered (wavelengths >560 nm transmitted) daylight balanced light exposures through a calibrated neutral step tablet, and then were developed using the color negative Kodak FlexicolorTM C41 process.
  • characteristic curves were plotted of density versus log exposure (log E, where E represents exposure in lux-seconds) obtained by employing development times of 1.75, 2.5, 3.25 and 6 minutes.
  • log E log exposure
  • the chosen characteristic curves were superimposed to obtain the best fit (maximum attainable superposition), and the lateral displacement that occurred as a result on the log E scale was taken as the speed difference.
  • Emulsion CC demonstrated that the combination of iridium dopant in the host tabular grains and a SET dopant in the epitaxy produced the best overall speed and the highest contrast. Further, the shift in contrast by Emulsion CC as a function of increased intensities of exposure was the lowest of the three emulsions compared.

Claims (11)

  1. Emulsion sensible aux rayonnements comprenant :
    (1) un milieu dispersant,
    (2) des grains d'halogénures d'argent, y compris des grains tabulaires
    (a) ayant des faces principales {111},
    (b) contenant plus de 70 pourcent en moles de bromure, par rapport à l'argent,
    (c) représentant plus de 90 pourcent de la surface totale projetée des grains,
    (d) présentant un diamètre circulaire équivalent moyen d'au moins 0,7 µm,
    (e) présentant une épaisseur moyenne inférieure à 0,07 µm,
    (f) contenant un dopant iridium capable de réduire l'écart à la loi de réciprocité sur la plage d'exposition allant de 1 x 10-2 à 1 x 10-5 seconde et
    (g) ayant des sites de sensibilisation chimique formant une image latente sur les surfaces des grains tabulaires, et
    (3) un colorant sensibilisateur spectral adsorbé à la surface des grains tabulaires, émulsion caractérisée en ce que :
       les sites de sensibilisation chimique superficielle contiennent des protubérances d'halogénures d'argent formant des jonctions épitaxiales avec les grains tabulaires, ces protubérances
    (a) étant situées sur 50 pourcent au maximum de la superficie des grains tabulaires,
    (b) ayant une solubilité globale plus élevée qu'au moins la partie des grains tabulaires formant des jonctions épitaxiales avec les protubérances,
    (c) formant un réseau cristallin cubique à faces centrées, et
    (d) contenant un dopant du Groupe VIII comprenant un ion métallique divalent du Groupe VIII choisi parmi Fe+2, Ru+2 ou Os+2 et au moins un coordinat plus attracteur d'électron que l'ion fluorure.
  2. Emulsion selon la revendication 1, caractérisée en ce que les protubérances contiennent une concentration de chlorure supérieure d'au moins 10 pourcent en moles à celle des grains tabulaires.
  3. Emulsion selon la revendication 2, caractérisée en ce que les protubérances contiennent une concentration d'ion chlorure supérieure d'au moins 20 pourcent en moles à celle desdits grains tabulaires.
  4. Emulsion selon les revendications 1 à 3, caractérisée en ce que les protubérances d'halogénures d'argent déposées par épitaxie sont situées sur moins de 25 pourcent des surfaces des grains tabulaires.
  5. Emulsion selon la revendication 4, caractérisée en que les protubérances d'halogénures d'argent déposées par épitaxie sont essentiellement situées au voisinage d'au moins l'un des bords et angles des grains tabulaires.
  6. Emulsion selon les revendications 1 à 5, caractérisée en que le dopant du complexe de coordination comprend Os2+ et au moins un coordinat cyano.
  7. Emulsion selon les revendications 1 à 5, caractérisée en ce que le dopant du complexe de coordination comprend Ru2+ ou Os2+ et au moins trois coordinats cyano.
  8. Emulsion selon les revendications 1 à 5, caractérisée en que le dopant du complexe de coordination comprend Fe2+, Ru2+ ou Os2+ et au moins cinq coordinats cyano.
  9. Emulsion selon les revendications 1 à 8, dans laquelle le dopant iridium est présent dans une région des grains tabulaires formée après la précipitation des premiers 20 pourcent et avant la précipitation des derniers 10 pourcent de l'argent formant les grains tabulaires.
  10. Emulsion améliorée selon l'une quelconque des revendications 1 à 9, caractérisée aussi en ce que les grains tabulaires présentent une épaisseur moyenne inférieure ou égale à 0,04 µm.
  11. Elément photographique comprenant :
    un support,
    une première couche d'émulsion aux halogénures d'argent appliquée sur le support et sensibilisée de manière à produire un enregistrement photographique lorsqu'elle est exposée à une lumière spéculaire dans la plage de longueurs d'onde visible minus bleu allant de 500 à 700 nm, et
    une seconde couche d'émulsion aux halogénures d'argent capable de produire un second enregistrement photographique, appliquée au-dessus de la première couche d'émulsion aux halogénures d'argent destinée à recevoir la lumière spéculaire minus bleu destinée à exposer la première couche d'émulsion aux halogénures d'argent, la seconde couche d'émulsion aux halogénures d'argent étant capable d'agir comme un milieu de transmission pour la distribution d'au moins une partie de la lumière minus bleu destinée à l'exposition de la première couche d'émulsion aux halogénures d'argent sous la forme d'une lumière spéculaire, caractérisée en ce que la seconde couche d'émulsion aux halogénures d'argent comprend une émulsion selon l'une quelconque des revendications 1 à 10 incluse.
EP19950420240 1994-08-26 1995-08-21 Emulsions aux grains tabulaires ultraminces avec gestion nouvelle de dopants Expired - Lifetime EP0699950B1 (fr)

Applications Claiming Priority (10)

Application Number Priority Date Filing Date Title
US441489 1989-11-24
US08/297,430 US5503971A (en) 1994-08-26 1994-08-26 Ultrathin tabular grain emulsions containing speed-granularity enhancements
US297195 1994-08-26
US297430 1994-08-26
US08/297,195 US5576168A (en) 1994-08-26 1994-08-26 Ultrathin tabular grain emulsions with sensitization enhancements
US08/296,562 US5503970A (en) 1994-08-26 1994-08-26 Ultrathin tabular grain emulsions with novel dopant management
US296562 1994-08-26
US359251 1994-12-19
US08/359,251 US5494789A (en) 1994-08-26 1994-12-19 Epitaxially sensitized ultrathin tabular grain emulsions
US08/441,489 US5614358A (en) 1995-05-15 1995-05-15 Ultrathin tabular grain emulsions with reduced reciprocity failure

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EP0699950A1 EP0699950A1 (fr) 1996-03-06
EP0699950B1 true EP0699950B1 (fr) 2000-05-24

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JP4053708B2 (ja) 2000-02-23 2008-02-27 富士フイルム株式会社 ハロゲン化銀写真乳剤及びこれを用いたハロゲン化銀写真感光材料
JP4053742B2 (ja) 2000-09-19 2008-02-27 富士フイルム株式会社 ハロゲン化銀写真乳剤
JP4053746B2 (ja) 2000-09-19 2008-02-27 富士フイルム株式会社 ハロゲン化銀写真乳剤及びこれを用いたハロゲン化銀写真感光材料
DE60143154D1 (de) 2001-04-17 2010-11-11 Fujifilm Corp Photographisches Silberhalogenidmaterial enthaltend einen Methinfarbstoff
US8370711B2 (en) 2008-06-23 2013-02-05 Ramot At Tel Aviv University Ltd. Interruption criteria for block decoding

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JPH08171163A (ja) 1996-07-02
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EP0699950A1 (fr) 1996-03-06

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