EP0617317A1 - Mit Oligomeren modifizierte Emulsionen tafelförmiger Körner - Google Patents

Mit Oligomeren modifizierte Emulsionen tafelförmiger Körner Download PDF

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EP0617317A1
EP0617317A1 EP94104411A EP94104411A EP0617317A1 EP 0617317 A1 EP0617317 A1 EP 0617317A1 EP 94104411 A EP94104411 A EP 94104411A EP 94104411 A EP94104411 A EP 94104411A EP 0617317 A1 EP0617317 A1 EP 0617317A1
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Prior art keywords
grain
silver
emulsion
grains
tabular
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French (fr)
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Sherril Austin Eastman Kodak Company Puckett
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Eastman Kodak Co
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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
    • G03C1/0053—Tabular grain emulsions with high content of silver chloride
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
    • G03C1/07—Substances influencing grain growth during silver salt formation
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
    • G03C1/08—Sensitivity-increasing substances
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
    • G03C1/08—Sensitivity-increasing substances
    • G03C1/10—Organic substances
    • G03C1/12—Methine and polymethine dyes
    • G03C1/14—Methine and polymethine dyes with an odd number of CH groups
    • G03C1/16—Methine and polymethine dyes with an odd number of CH groups with one CH group
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
    • G03C1/08—Sensitivity-increasing substances
    • G03C1/10—Organic substances
    • G03C1/12—Methine and polymethine dyes
    • G03C1/14—Methine and polymethine dyes with an odd number of CH groups
    • G03C1/18—Methine and polymethine dyes with an odd number of CH groups with three CH groups
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/015—Apparatus or processes for the preparation of emulsions
    • G03C2001/0156—Apparatus or processes for the preparation of emulsions pAg value; pBr value; pCl value; pI value
    • 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
    • G03C1/035—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein characterised by the crystal form or composition, e.g. mixed grain
    • G03C2001/03558—Iodide content
    • 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
    • G03C2001/0854—Indium
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C2200/00—Details
    • G03C2200/01—100 crystal face

Definitions

  • the invention relates to radiation sensitive silver halide emulsions and to processes for their preparation.
  • An emulsion is generally understood to be a "tabular grain emulsion" when tabular grains account for at least 50 percent of total grain projected area.
  • a grain is generally considered to be a tabular grain when the ratio of its equivalent circular diameter (ECD) to its thickness (t) is at least 2.
  • the equivalent circular diameter of a grain is the diameter of a circle having an area equal to the projected area of the grain.
  • intermediate aspect ratio tabular grain emulsion refers to an emulsion which has an average tabular grain aspect ratio in the range of from 5 to 8.
  • the term “high aspect ratio tabular grain emulsion” refers to an emulsion which has an average tabular grain aspect ratio of greater than 8.
  • thin tabular grain is generally understood to be a tabular grain having a thickness of less than 0.2 ⁇ m.
  • ultrathin tabular grain is generally understood to be a tabular grain having a thickness of 0.06 ⁇ m or less.
  • high chloride refers to grains that contain at least 50 mole percent chloride based on silver. In referring to grains of mixed halide content, the halides are named in order of increasing molar concentrations--e.g., silver iodochloride contains a higher molar concentration of chloride than iodide.
  • tabular grain emulsions contain tabular grains that are irregular octahedral grains.
  • Regular octahedral grains contain eight identical crystal faces, each lying in a different ⁇ 111 ⁇ crystallographic plane.
  • Tabular irregular octahedra contain two or more parallel twin planes that separate two major grain faces lying in ⁇ 111 ⁇ crystal-lographic planes.
  • the ⁇ 111 ⁇ major faces of the tabular grains exhibit a threefold symmetry, appearing triangular or hexagonal. It is generally accepted that the tabular shape of the grains is the result of the twin planes producing favored edge sites for silver halide deposition, with the result that the grains grow laterally while increasing little, if any, in thickness after parallel twin plane incorporation.
  • Maskasky U.S. Patent 4,400,463 developed a strategy for preparing a high chloride emulsion containing tabular grains with parallel twin planes and ⁇ 111 ⁇ major crystal faces with the significant advantage of tolerating significant internal inclusions of the other halides.
  • the strategy was to use a particularly selected synthetic polymeric peptizer in combination with a grain growth modifier having as its function to promote the formation of ⁇ 111 ⁇ crystal faces.
  • Adsorbed aminoazaindenes, preferably adenine, and iodide ions were disclosed to be useful grain growth modifiers.
  • Maskasky U.S. Patent 4,713,323 significantly advanced the state of the art by preparing high chloride emulsions containing tabular grains with parallel twin planes and ⁇ 111 ⁇ major crystal faces using an aminoazaindene growth modifier and a gelatino-peptizer containing up to 30 micromoles per gram of methionine. Since the methionine content of a gelatino-peptizer, if objectionably high, can be readily reduced by treatment with a strong oxidizing agent (or alkylating agent, King et al U.S. Patent 4,942,120), Maskasky II placed within reach of the art high chloride tabular grain emulsions with significant bromide and iodide ion inclusions prepared starting with conventional and universally available peptizers.
  • a strong oxidizing agent or alkylating agent, King et al U.S. Patent 4,942,120
  • Bogg U.S. Patent 4,063,951 reported the first tabular grain emulsions in which the tabular grains had parallel ⁇ 100 ⁇ major crystal faces.
  • the tabular grains of Bogg exhibited square or rectangular major faces, thus lacking the threefold symmetry of conventional tabular grain ⁇ 111 ⁇ major crystal faces.
  • Bogg employed an ammoniacal ripening process for preparing silver bromoiodide tabular grains having aspect ratios ranging from 4:1 to 1:1.
  • the average aspect ratio of the emulsion was reported to be 2, with the highest aspect ratio grain (grain A in Figure 3) being only 4.
  • Bogg states that the emulsions can contain no more than 1 percent iodide and demonstrates only a 99.5% bromide 0.5% iodide emulsion. Attempts to prepare tabular grain emulsions by the procedures of Bogg have been unsuccessful.
  • Mignot U.S. Patent 4,386,156 represents an improvement over Bogg in that the disadvantages of ammoniacal ripening were avoided in preparing a silver bromide emulsion containing tabular grains with square and rectangular major faces.
  • Mignot specifically requires ripening in the absence of silver halide ripening agents other than bromide ion (e.g., thiocyanate, thioether or ammonia).
  • Evans et al U.S. Patent 5,024,931 discloses a photographic silver halide emulsion comprised of radiation sensitive silver halide grains exhibiting a face centered cubic crystal lattice structure containing on average, at least one pair of metal ions chosen from group VIII, periods 5 and 6, at adjacent cation sites of the crystal lattice. Increased speed and reduced low intensity reciprocity failure are demonstrated in silver bromide emulsions.
  • the invention is directed to a radiation sensitive emulsion containing a silver halide grain population comprised of at least 50 mole percent chloride, based on total silver forming the grain population projected area, characterized in that at least 50 percent of total grain projected area is accounted for by tabular grains (1) bounded by ⁇ 100 ⁇ major faces having adjacent edge ratios of less than 10, (2) each having an aspect ratio of at least 2, and (3) containing on average at least one pair of metal ions chosen from group VIII, periods 5 and 6, at adjacent cation sites in their crystal lattice.
  • this invention is directed to a process of preparing a radiation sensitive emulsion containing a dispersing medium and silver halide grains, characterized in that at least 50 percent of total grain projected area is accounted for by tabular grains (1) bounded by ⁇ 100 ⁇ major faces having adjacent edge ratios of less than 10, (2) each having an aspect ratio of at least 2, (3) containing on average at least one pair of metal ions chosen from group VIII, periods 5 and 6, at adjacent cation sites in their crystal lattice, and (4) internally at their nucleation site containing iodide and at least 50 mole percent chloride are prepared by the steps comprised of (a) introducing silver and halide salts into a dispersing medium so that nucleation of the tabular grains occurs in the presence of iodide with chloride accounting for at least 50 mole percent of the halide present in the dispersing medium and the pCl of the dispersing medium being maintained in the range of from 0.5 to 3.5, (b) following nucleation completing grain
  • the present invention has been facilitated by the discovery of a novel approach to forming tabular grains. Instead of introducing parallel twin planes in grains as they are being formed to induce tabularity and thereby produce tabular grains with ⁇ 111 ⁇ major faces, it has been discovered that the presence of iodide in the dispersing medium during a high chloride nucleation step coupled with maintaining the chloride ion in solution within a selected pCl range results in the formation of a tabular grain emulsion in which the tabular grains are bounded by ⁇ 100 ⁇ crystal faces.
  • the present invention combines with the novel grain characteristics adjacent cation crystal lattice site grain dopants that are highly effective in improving photographic performance.
  • the invention represent the discovery of a novel process for preparing tabular grain emulsions, the emulsions that are produced by the process are novel.
  • the invention places within the reach of the art tabular grains bounded by ⁇ 100 ⁇ crystal faces with halide contents, dopant contents and distributions and grain thicknesses that have not been heretofore realized.
  • the present invention provides ultrathin tabular grain emulsion in which the grains are bounded by ⁇ 100 ⁇ crystal faces.
  • the invention in a preferred form provides intermediate and high aspect ratio tabular grain high chloride emulsions exhibiting high levels of grain stability.
  • the emulsions of the invention do not require a morphological stabilizer adsorbed to the major faces of the grains to maintain their tabular form.
  • silver chloride and silver bromochloride emulsions each of which can be prepared by variant precipitation procedures that do not require the presence of iodide ion during grain nucleation.
  • the photographically useful, radiation sensitive emulsions of the invention are comprised of a dispersing medium and silver halide grains.
  • the emulsions contain a high chloride grain population. At least 50 percent of total grain projected area of the high chloride grain population is accounted for by tabular grains which (1) are bounded by ⁇ 100 ⁇ major faces having adjacent edge ratios of less than 10, (2) each have an aspect ratio of at least 2, and (3) contain on average at least one pair of metal ions chosen from group VIII, periods 5 and 6, at adjacent cation sites in the crystal lattice.
  • Figure 1 is a shadowed photomicrograph of carbon grain replicas of a representative emulsion of the invention, described in detail in Example 1 below. It is immediately apparent that most of the grains have orthogonal tetragonal (square or rectangular) faces. The orthogonal tetragonal shape of the grain faces indicates that they are ⁇ 100 ⁇ crystal faces.
  • rods acicular or rod-like grains
  • These grains are more than 10 times longer in one dimension than in any other dimension and can be excluded from the desired tabular grain population based on their high ratio of edge lengths.
  • the projected area accounted for by the rods is low, but, when rods are present, their projected area is noted for determining total grain projected area.
  • ECD is determined by measuring the projected area (the product of edge lengths) of the upper surface of each grain. From the grain projected area the ECD of the grain is calculated.
  • Grain thickness is commonly determined by oblique illumination of the grain population resulting in the individual grains casting shadows. From a knowledge of the shadow angle it is possible to calculate the thickness of a grain from a measurement of its shadow length.
  • the grains having square or rectangular faces and each having a ratio of ECD/t of at least 2 are tabular grains having ⁇ 100 ⁇ major faces. When the projected areas of the ⁇ 100 ⁇ tabular grains account for at least 50 percent of total grain projected area, the emulsion is a tabular grain emulsion.
  • tabular grains account for more than 50 percent of total grain projected area. From the definition of a tabular grain above, it is apparent that the average aspect ratio of the tabular grains can only approach 2 a minimum limit. In fact, tabular grain emulsions of the invention typically exhibit average aspect ratios of 5 or more, with high average aspect ratios (>8) being preferred. That is, preferred emulsions according to the invention are high aspect ratio tabular grain emulsions. In specifically preferred emulsions according to the invention average aspect ratios of the tabular grain population are at least 12 and optimally at least 20. Typically the average aspect ratio of the tabular grain population ranges up to 50, but higher aspect ratios of 100, 200 or more can be realized.
  • Emulsions within the contemplation of the invention in which the average aspect ratio approaches the minimum average aspect ratio limit of 2 still provide a surface to volume ratio that is 200 percent that of cubic grains.
  • the tabular grain population can exhibit any grain thickness that is compatible with the average aspect ratios noted above. However, particularly when the selected tabular grain population exhibits a high average aspect ratio, it is preferred to additionally limit the grains included in the selected tabular grain population to those that exhibit a thickness of less than 0.3 ⁇ m and, optimally, less than 0.2 ⁇ m. It is appreciated that the aspect ratio of a tabular grain can be limited either by limiting its equivalent circular diameter or increasing its thickness.
  • the tabular grains accounting for at least 50 percent of total grain projected area can also each exhibit a grain thickness of less than 0.3 ⁇ m or less than 0.2 ⁇ m.
  • the aspect ratio range of from 2 to 8 particularly, there are specific photographic applications that can benefit by greater tabular grain thicknesses.
  • tabular grain thicknesses that are on average 1 ⁇ m or even larger can be tolerated. This is because the eye is least sensitive to the blue record and hence higher levels of image granularity (noise) can be tolerated without objection.
  • the tabular grain population preferably exhibits major face edge length ratios of less than 5 and optimally less than 2.
  • the tabular grain population accounting for at least 50 percent of total grain projected area is provided by tabular grains also exhibiting 0.2 ⁇ m.
  • the emulsions are in this instance thin tabular grain emulsions.
  • ultrathin tabular grain emulsions have been prepared satisfying the requirements of the invention.
  • Ultrathin tabular grain emulsions are those in which the selected tabular grain population is made up of tabular grains having thicknesses of less than 0.06 ⁇ m.
  • the only ultrathin tabular grain emulsions of a halide content exhibiting a cubic crystal lattice structure known in the art contained tabular grains bounded by ⁇ 111 ⁇ major faces. In other words, it was thought essential to form tabular grains by the mechanism of parallel twin plane incorporation to achieve ultrathin dimensions.
  • Emulsions according to the invention can be prepared in which the tabular grain population has a mean thickness down to 0.02 ⁇ m and even 0.01 ⁇ m.
  • Ultrathin tabular grains have extremely high surface to volume ratios. This permits ultrathin grains to be photographically processed at accelerated rates. Further, when spectrally sensitized, ultrathin tabular grains exhibit very high ratios of speed in the spectral region of sensitization as compared to the spectral region of native sensitivity. For example, ultrathin tabular grain emulsions according to the invention can have entirely negligible levels of blue sensitivity, and are therefore capable of providing a green or red record in a photographic product that exhibits minimal blue contamination even when located to receive blue light.
  • the high chloride tabular grain population accounting for 50 percent of total grain projected area preferably exhibits a tabularity of greater than 25 and most preferably greater than 100. Since the tabular grain population can be ultrathin, it is apparent that extremely high tabularities, ranging to 1000 and above are within the contemplation of the invention.
  • the tabular grain population can exhibit an average ECD of any photographically useful magnitude.
  • ECD's for photographic utility average ECD's of less than 10 ⁇ m are contemplated, although average ECD's in most photographic applications rarely exceed 6 ⁇ m.
  • intermediate aspect ratios with ECD's of the tabular grain population of 0.10 ⁇ m and less.
  • emulsions with selected tabular grain populations having higher ECD's are advantageous for achieving relatively high levels of photographic sensitivity while selected tabular grain populations with lower ECD's are advantageous in achieving low levels of granularity.
  • the advantageous properties of the emulsions of the invention are increased as the proportion of tabular grains having ⁇ 100 ⁇ major faces is increased.
  • the preferred emulsions according to the invention are those in which at least 70 percent and optimally at least 90 percent of total grain projected area is accounted for by tabular grains having ⁇ 100 ⁇ major faces. It is specifically contemplated to provide emulsions satisfying the grain descriptions above in which the selection of the rank ordered tabular grains extends to sufficient tabular grains to account for 70 percent or even 90 percent of total grain projected area.
  • the emulsion does not satisfy the requirements of the invention and is, in general, a photographically inferior emulsion.
  • emulsions are photographically inferior in which many or all of the tabular grains are relatively thick--e.g., emulsions containing high proportions of tabular grains with thicknesses in excess of 0.3 ⁇ m.
  • inferior emulsions failing to satisfy the requirements of the invention have an excessive proportion of total grain projected area accounted for by cubes, twinned nontabular grains, and rods. Such an emulsion is shown in Figure 2. Most of the grain projected area is accounted for by cubic grains. Also the rod population is much more pronounced than in Figure 1. A few tabular grains are present, but they account for only a minor portion of total grain projected area.
  • the tabular grain emulsion of Figure 1 satisfying the requirements of the invention and the predominantly cubic grain emulsion of Figure 2 were prepared under conditions that were identical, except for iodide management during nucleation.
  • the Figure 2 emulsion is a silver chloride emulsion while the emulsion of Figure 1 additionally includes a small amount of iodide introduced during grain nucleation.
  • the tabular grains described above accounting for at least 50 percent of total grain projected area and preferably all of the grains that are formed in the same precipitation contain on average at least one pair of metal ions chosen from group VIII, periods 5 and 6, at adjacent cation sites in their crystal lattice. Subsequent references to group VIII, periods 5 and 6, are also more succinctly designated group VIII 5/6.
  • the present invention is based on the discovery that, when adjacent cation positions of the face centered cubic crystal structure of the grains are occupied by group VIII 5/6 metal ions, they exhibit a disproportionately large effect on photographic performance as compared to that demonstrated by photographic emulsions in which the same group VIII 5/6 metal ions have been similarly introduced, but without any mechanism to achieve adjacent cation lattice placement. While a single pair, on average, of adjacent group VIII 5/6 metal ions incorporated in the crystal lattice of the radiation sensitive grains of an emulsion is effective to enhance photographic performance, it is preferred to incorporate at least five pairs, on average, of adjacent group VIII 5/6 metal ions in the radiation sensitive grains, preferably at least ten pairs, on average.
  • Average pair incorporations can be determined merely by dividing half the number of metal ions incorporated by the number of radiation sensitive silver halide grains present in the emulsion. The latter can be determined from a knowledge of mean grain size, grain shape, and the halide and silver content of the emulsion. The actual distribution of group VIII 5/6 metal ions within the grains can be expected to follow a Poisson error function distribution with the mean metal ion incorporation corresponding to the distribution mode.
  • the minimum group VIII 5/6 metal ion incorporations per grain satisfying the requirements of this invention are far below the minimum concentration levels of group VIII 5/6 metal ions taught to be effective by the art.
  • Smith and Trivelli U.S. Patent 2,448,060 discloses a minimum concentration of group VIII 5/6 metal coordination complex of 0.8 mg/100 grams of silver.
  • the coordination complex concentration in mg/100 grams of silver is still less than a 1/3 the minimum level taught to be effective by Smith and Trivelli.
  • group VIII 5/6 metal ions Once a sufficient number of adjacent pairs of group VIII 5/6 metal ions are incorporated into the grains to achieve maximum photographic efficiency, no useful purpose is realized by further increasing the presence of group VIII 5/6 metal ions.
  • the present invention does not, however, prevent the inclusion of group VIII 5/6 metal ions, incorporated entirely or only partially as adjacent lattice position pairs, up to the maximum useful concentration levels taught in the art for group VIII 5/6 metal ion incorporation.
  • group VIII metal ions from period 5 are incorporated at the concentration limit of Smith and Trivelli, less than approximately 40 mg/100 grams of silver, only elementary calculations are required to observe that there are only about 4 atoms of the period 5 group VIII metal per 10,000 atoms of silver.
  • group VIII metal is chosen from period 6, this number is reduced by half to about 2 atoms per 10,000 atoms of silver.
  • Smith and Trivelli set out as a preferred maximum less than approximately 20 mg/100 grams of silver, which amounts to only about 2 atoms of group VIII 5 metal or 1 atom of group VIII 6 metal per 10,000 atoms of silver.
  • oligomeric hexacoordination complex containing at least two group VIII 5/6 metal atoms.
  • polymeric and oligomeric hexacoordination complexes are known having a higher number of group VIII 5/6 metal ions, those oligomers are preferred which contain up to about 20 group VIII 5/6 metal atoms. Specifically preferred are oligomers that contain about 6 to 10 group VIII 5/6 metal atoms.
  • the oligomeric coordination complexes contain two or more group VIII 5/6 metal atoms linked by bridging ligands.
  • R2MX6 where R represents hydrogen, alkali metal, or ammonium, M represents a group VIII, period 5 or 6, metal (i.e., ruthenium, rhodium, palladium, osmium, iridium or platinum), and X represents a halogen atom.
  • R represents hydrogen, alkali metal, or ammonium
  • M represents a group VIII, period 5 or 6
  • metal i.e., ruthenium, rhodium, palladium, osmium, iridium or platinum
  • X represents a halogen atom.
  • the six halide ligands are positioned around the group VIII 5/6 metal atom in the same way that the halide ions are positioned around a single silver ion in the face centered crystal lattice structure of a silver halide grain.
  • two ligands lie along each of these three axes equally spaced from the group VIII 5/6 metal atom.
  • a corresponding anionic hexacoordination complex containing two group VIII 5/6 metal atoms is represented by the following formula: (III) M2L10 wherein M is as previously defined and L is a halide or other bridging ligand.
  • oligomers consist of rings containing six group VIII 5/6 metal atoms, usually with a pair of metal atoms in one ring shared with a pair of metal atoms in an adjacent ring.
  • the following are exemplary of oligomeric anions satisfying the requirements of the invention containing 6, 8 or 10 group VIII 5/6 metal atoms: (V) M6L24 (VI) M8L32 (VII) M10L38 wherein M and L are as previously defined.
  • Other oligomeric forms containing 6, 8 or 10 group VIII 5/6 metal atoms are, of course, possible.
  • the oligomers are capable of presenting the group VIII metal atoms of the oligomers to the surface of the crystal lattice structure as it is being formed so that adjacent group VIII 5/6 atoms are oriented to occupy adjacent cation sites of the crystal lattice structure. It is also possible to achieve adjacent incorporations of group VIII metal atoms employing oligomeric tetracoordination complexes in place of hexacoordination complexes.
  • the bridging ligands are capable of forming covalent bonds with two adjacent group VIII 5/6 metal atoms.
  • the ligands can be halides, such as fluoride, chloride, bromide, or iodide atoms.
  • the ligands are preferably chloride or bromide ligands.
  • Other bridging ligand choices in addition to halide ions are possible. For example, to a limited extent aquo (HOH) ligands can be substituted for halide ligands.
  • Pseudohalogen ligands such as cyanide (CN), cyanate (OCN), thiocyanate (SCN), selenocyanate (SeCN), and tellurocyanate (TeCN) ligands are contemplated. Still other ligands, such as nitrosyl (NO), thionitrosyl (NS), azide (N3), oxo (O), and carbonyl (CO) ligands are possible.
  • ligands other than halide and aquo ligands it must be borne in mind that the ligands can themselves affect photographic performance. When the ligands are the same halide as that of the grain structure, modifying effects are entirely attributable to the group VIII 5/6 metal ions incorporated. Similarly, aquo ligands have not been reported to produce modifying effects.
  • the anionic hexacoordination complexes paired with one or more charge satisfying cations can be introduced as a particulate solid or in solution at any stage of emulsion preparation employing any convenient conventional technique for hexacoordination complex addition--e.g., as taught by Smith and Trivelli, cited above and here incorporated by reference.
  • any convenient conventional technique for hexacoordination complex addition--e.g., as taught by Smith and Trivelli, cited above and here incorporated by reference To insure incorporation of the group VIII 5/6 metal in the crystal structure it is preferred to have the hexacoordination complex present during grain formation. Having the complex present before or during silver halide precipitation is contemplated.
  • the group VIII 5/6 metal can be effectively incorporated by having the complex present while surface ripening of the grains is occurring--i.e., having the complex and one or more ripening agents concurrently present in the emulsion.
  • concentrations of the group VIII 5/6 metals introduced into the grains are too low to exert any significant influence on the shape or distribution of the grains produced.
  • emulsions satisfying the requirements of the invention has been achieved by the discovery of a novel precipitation process.
  • grain nucleation occurs in a high chloride environment in the presence of iodide ion under conditions that favor the emergence of ⁇ 100 ⁇ crystal faces.
  • iodide ion the inclusion of iodide into the cubic crystal lattice being formed by silver ions and the remaining halide ions is disruptive because of the much larger diameter of iodide ion as compared to chloride ion.
  • the incorporated iodide ions introduce crystal irregularities that in the course of further grain growth result in tabular grains rather than regular (cubic) grains.
  • a reaction vessel containing a dispersing medium and conventional silver and reference electrodes for monitoring halide ion concentrations within the dispersing medium.
  • Halide ion is introduced into the dispersing medium that is at least 50 mole percent chloride--i.e., at least half by number of the halide ions in the dispersing medium are chloride ions.
  • the pCl of the dispersing medium is adjusted to favor the formation of ⁇ 100 ⁇ grain faces on nucleation--that is, within the range of from 0.5 to 3.5, preferably within the range of from 1.0 to 3.0 and, optimally, within the range of from 1.5 to 2.5.
  • the grain nucleation step is initiated when a silver jet is opened to introduce silver ion into the dispersing medium.
  • Iodide ion is preferably introduced into the dispersing medium concurrently with or, optimally, before opening the silver jet.
  • Effective tabular grain formation can occur over a wide range of iodide ion concentrations ranging up to the saturation limit of iodide in silver chloride.
  • the saturation limit of iodide in silver chloride is reported by H. Hirsch, "Photographic Emulsion Grains with Cores: Part I. Evidence for the Presence of Cores", J. of Photog. Science, Vol. 10 (1962), pp. 129-134, to be 13 mole percent.
  • iodide grains in which equal molar proportions of chloride and bromide ion are present up to 27 mole percent iodide, based on silver, can be incorporated in the grains. It is preferred to undertake grain nucleation and growth below the iodide saturation limit to avoid the precipitation of a separate silver iodide phase and thereby avoid creating an additional category of unwanted grains. It is generally preferred to maintain the iodide ion concentration in the dispersing medium at the outset of nucleation at less than 10 mole percent. In fact, only minute amounts of iodide at nucleation are required to achieve the desired tabular grain population. Initial iodide ion concentrations of down to 0.001 mole percent are contemplated. However, for convenience in replication of results, it is preferred to maintain initial iodide concentrations of at least 0.01 mole percent and, optimally, at least 0.05 mole percent.
  • silver iodochloride grain nuclei are formed during the nucleation step. Minor amounts of bromide ion can be present in the dispersing medium during nucleation. Any amount of bromide ion can be present in the dispersing medium during nucleation that is compatible with at least 50 mole percent of the halide in the grain nuclei being chloride ions.
  • the grain nuclei preferably contain at least 70 mole percent and optimally at least 90 mole percent chloride ion, based on silver.
  • Grain nuclei formation occurs instantaneously upon introducing silver ion into the dispersing medium.
  • silver ion introduction during the nucleation step is preferably extended for a convenient period, typically from 5 seconds to less than a minute. So long as the pCl remains within the ranges set forth above no additional chloride ion need be added to the dispersing medium during the nucleation step. It is, however, preferred to introduce both silver and halide salts concurrently during the nucleation step.
  • the advantage of adding halide salts concurrently with silver salt throughout the nucleation step is that this permits assurance that any grain nuclei formed after the outset of silver ion addition are of essentially similar halide content as those grain nuclei initially formed.
  • Iodide ion addition during the nucleation step is particularly preferred. Since the deposition rate of iodide ion far exceeds that of the other halides, iodide will be depleted from the dispersing medium unless replenished.
  • Silver ion is preferably introduced as an aqueous silver salt solution, such as a silver nitrate solution.
  • Halide ion is preferably introduced as alkali or alkaline earth halide, such as lithium, sodium and/or potassium chloride, bromide and/or iodide.
  • the dispersing medium contained in the reaction vessel prior to the nucleation step is comprised of water, the dissolved halide ions discussed above and a peptizer.
  • the dispersing medium can exhibit a pH within any convenient conventional range for silver halide precipitation, typically from 2 to 8. It is preferred, but not required, to maintain the pH of the dispersing medium on the acid side of neutrality (i.e., ⁇ 7.0). To minimize fog a preferred pH range for precipitation is from 2.0 to 5.0.
  • Mineral acids such as nitric acid or hydrochloride acid, and bases, such as alkali hydroxides, can be used to adjust the pH of the dispersing medium. It is also possible to incorporate pH buffers.
  • the peptizer can take any convenient conventional form known to be useful in the precipitation of photographic silver halide emulsions and particularly tabular grain silver halide emulsions.
  • a summary of conventional peptizers is provided in Research Disclosure, Vol. 308, December 1989, Item 308119, Section IX. Research Disclosure is published by Kenneth Mason Publications, Ltd., Emsworth, Hampshire P010 7DD, England. While synthetic polymeric peptizers of the type disclosed by Maskasky I, cited above and here incorporated by reference, can be employed, it is preferred to employ gelatino peptizers (e.g., gelatin and gelatin derivatives).
  • gelatino peptizers typically contain significant concentrations of calcium ion, although the use of deionized gelatino peptizers is a known practice. In the latter instance it is preferred to compensate for calcium ion removal by adding divalent or trivalent metal ions, such alkaline earth or earth metal ions, preferably magnesium, calcium, barium or aluminum ions.
  • peptizers are low methionine gelatino peptizers (i.e., those containing less than 30 micromoles of methionine per gram of peptizer), optimally less than 12 micromoles of methionine per gram of peptizer, these peptizers and their preparation are described by Maskasky II and King et al, cited above, the disclosures of which are here incorporated by reference.
  • the grain growth modifiers of the type taught for inclusion in the emulsions of Maskasky I and II are not appropriate for inclusion in the dispersing media of this invention, since these grain growth modifiers promote twinning and the formation of tabular grains having ⁇ 111 ⁇ major faces.
  • adenine e.g., adenine
  • the grain growth modifiers promote twinning and the formation of tabular grains having ⁇ 111 ⁇ major faces.
  • at least about 10 percent and typically from 20 to 80 percent of the dispersing medium forming the completed emulsion is present in the reaction vessel at the outset of the nucleation step. It is conventional practice to maintain relatively low levels of peptizer, typically from 10 to 20 percent of the peptizer present in the completed emulsion, in the reaction vessel at the start of precipitation.
  • the concentration of the peptizer in the dispersing medium be in the range of from 0.5 to 6 percent by weight of the total weight of the dispersing medium at the outset of the nucleation step. It is conventional practice to add gelatin, gelatin derivatives and other vehicles and vehicle extenders to prepare emulsions for coating after precipitation. Any naturally occurring level of methionine can be present in gelatin and gelatin derivatives added after precipitation is complete.
  • the nucleation step can be performed at any convenient conventional temperature for the precipitation of silver halide emulsions. Temperatures ranging from near ambient--e.g., 30°C up to about 90°C are contemplated, with nucleation temperatures in the range of from 35 to 70°C being preferred.
  • a grain growth step follows the nucleation step in which the grain nuclei are grown until tabular grains having ⁇ 100 ⁇ major faces of a desired average ECD are obtained.
  • the objective of the nucleation step is to form a grain population having the desired incorporated crystal structure irregularities
  • the objective of the growth step is to deposit additional silver halide onto (grow) the existing grain population while avoiding or minimizing the formation of additional grains. If additional grains are formed during the growth step, the polydispersity of the emulsion is increased and, unless conditions in the reaction vessel are maintained as described above for the nucleation step, the additional grain population formed in the growth step will not have the desired tabular grain properties described above.
  • the process of preparing emulsions according to the invention can be performed as a single jet precipitation without interrupting silver ion introduction from start to finish.
  • a spontaneous transition from grain formation to grain growth occurs even with an invariant rate of silver ion introduction, since the increasing size of the grain nuclei increases the rate at which they can accept silver and halide ion from the dispersing medium until a point is reached at which they are accepting silver and halide ions at a sufficiently rapid rate that no new grains can form.
  • single jet precipitation limits halide content and profiles and generally results in more polydisperse grain populations.
  • emulsions In the preparation of emulsions according to the invention it is preferred to interrupt silver and halide salt introductions at the conclusion of the nucleation step and before proceeding to the growth step that brings the emulsions to their desired final size and shape.
  • the emulsions are held within the temperature ranges described above for nucleation for a period sufficient to allow reduction in grain dispersity.
  • a holding period can range from a minute to several hours, with typical holding periods ranging from 5 minutes to an hour.
  • relatively smaller grain nuclei are Ostwald ripened onto surviving, relatively larger grain nuclei, and the overall result is a reduction in grain dispersity.
  • the rate of ripening can be increased by the presence of a ripening agent in the emulsion during the holding period.
  • a conventional simple approach to accelerating ripening is to increase the halide ion concentration in the dispersing medium. This creates complexes of silver ions with plural halide ions that accelerate ripening.
  • ripening can be accelerated and the percentage of total grain projected area accounted for by ⁇ 100 ⁇ tabular grains can be increased by employing conventional ripening agents.
  • Preferred ripening agents are sulfur containing ripening agents, such as thioethers and thiocyanates.
  • Typical thiocyanate ripening agents are disclosed by Nietz et al U.S. Patent 2,222,264, Lowe et al U.S. Patent 2,448,534 and Illingsworth U.S. Patent 3,320,069, the disclosures of which are here incorporated by reference.
  • Typical thioether ripening agents are disclosed by McBride U.S. Patent 3,271,157, Jones U.S. Patent 3,574,628 and Rosencrantz et al U.S. Patent 3,737,313, the disclosures of which are here incorporated by reference.
  • crown thioethers More recently crown thioethers have been suggested for use as ripening agents. Ripening agents containing a primary or secondary amino moiety, such as imidazole, glycine or a substituted derivative, are also effective. Sodium sulfite has also been demonstrated to be effective in increasing the percentage of total grain projected accounted by the ⁇ 100 ⁇ tabular grains.
  • grain growth to obtain the emulsions of the invention can proceed according to any convenient conventional precipitation technique for the precipitation of silver halide grains bounded by ⁇ 100 ⁇ grain faces.
  • any halide or combination of halides known to form a cubic crystal lattice structure can be employed during the growth step.
  • iodide nor chloride ions need be incorporated in the grains during the growth step, since the irregular grain nuclei faces that result in tabular grain growth, once introduced, persist during subsequent grain growth independently of the halide being precipitated, provided the halide or halide combination is one that forms a cubic crystal lattice.
  • silver bromide or silver iodobromide When silver bromide or silver iodobromide is being deposited during the growth step, it is preferred to maintain a pBr within the dispersing medium in the range of from 1.0 to 4.2, preferably 1.6 to 3.4.
  • a pBr When silver chloride, silver iodochloride, silver bromochloride or silver iodobromochloride is being deposited during the growth step, it is preferred to maintain the pCl within the dispersing medium within the ranges noted above in describing the nucleation step.
  • both silver and halide salts are preferably introduced into the dispersing medium.
  • double jet precipitation is contemplated, with added iodide salt, if any, being introduced with the remaining halide salt or through an independent jet.
  • the rate at which silver and halide salts are introduced is controlled to avoid renucleation--that is, the formation of a new grain population. Addition rate control to avoid renucleation is generally well known in the art, as illustrated by Wilgus German OLS No. 2,107,118, Irie U.S. Patent 3,650,757, Kurz U.S. Patent 3,672,900, Saito U.S.
  • nucleation and growth stages of grain precipitation occur in the same reaction vessel. It is, however, recognized that grain precipitation can be interrupted, particularly after completion of the nucleation stage. Further, two separate reaction vessels can be substituted for the single reaction vessel described above.
  • the nucleation stage of grain preparation can be performed in an upstream reaction vessel (herein also termed a nucleation reaction vessel) and the dispersed grain nuclei can be transferred to a downstream reaction vessel in which the growth stage of grain precipitation occurs (herein also termed a growth reaction vessel).
  • an enclosed nucleation vessel can be employed to receive and mix reactants upstream of the growth reaction vessel, as illustrated by Posse et al U.S.
  • peptizers that exhibit reduced adhesion to grain surfaces.
  • low methionine gelatin of the type disclosed by Maskasky II is less tightly absorbed to grain surfaces than gelatin containing higher levels of methionine.
  • Further moderated levels of grain adsorption can be achieved with so-called “synthetic peptizers"--that is, peptizers formed from synthetic polymers.
  • the maximum quantity of peptizer compatible with limited coalescence of grain nuclei is, of course, related to the strength of adsorption to the grain surfaces.
  • the emulsions of the invention include silver chloride, silver iodochloride emulsions, silver iodobromochloride emulsions and silver iodochloro-bromide emulsions.
  • Conventional grain dopants (other than group VIII metal dopants), in concentrations of up to 10 ⁇ 2 mole per silver mole and typically less than 10 ⁇ 4 mole per silver mole, can be present in the grains.
  • compounds of metals such as copper, thallium, lead, mercury, bismuth, zinc, cadmium and rhenium can be present during grain precipitation, preferably during the growth stage of precipitation.
  • Conventional grain dopant selections are illustrated by Research Disclosure , Vol. 308, Dec. 1989, Item 308,119, Section I, subsection D.
  • the invention is particularly advantageous in providing high chloride (greater than 50 mole percent chloride) tabular grain emulsions, since conventional high chloride tabular grain emulsions having tabular grains bounded by ⁇ 111 ⁇ are inherently unstable and require the presence of a morphological stabilizer to prevent the grains from regressing to nontabular forms.
  • Particularly preferred high chloride emulsions are according to the invention that are those that contain more than 70 mole percent (optimally more than 90 mole percent) chloride.
  • a further procedure that can be employed to maximize the population of tabular grains having ⁇ 100 ⁇ major faces is to incorporate an agent capable of restraining the emergence of non- ⁇ 100 ⁇ grain crystal faces in the emulsion during its preparation.
  • the restraining agent when employed, can be active during grain nucleation, during grain growth or throughout precipitation.
  • Useful restraining agents under the contemplated conditions of precipitation are organic compounds containing a nitrogen atom with a resonance stabilized ⁇ electron pair. Resonance stabilization prevents protonation of the nitrogen atom under the relatively acid conditions of precipitation.
  • Aromatic resonance can be relied upon for stabilization of the ⁇ electron pair of the nitrogen atom.
  • the nitrogen atom can either be incorporated in an aromatic ring, such as an azole or azine ring, or the nitrogen atom can be a ring substituent of an aromatic ring.
  • the restraining agent can satisfy the following formula: where Z represents the atoms necessary to complete a five or six membered aromatic ring structure, preferably formed by carbon and nitrogen ring atoms.
  • Preferred aromatic rings are those that contain one, two or three nitrogen atoms.
  • Specifically contemplated ring structures include 2H-pyrrole, pyrrole, imidazole, pyrazole, 1,2,3-triazole, 1,2,4-triazole, 1,3,5-triazole, pyridine, pyrazine, pyrimidine, and pyridazine.
  • Ar is an aromatic ring structure containing from 5 to 14 carbon atoms and R1 and R2 are independently hydrogen, Ar, or any convenient aliphatic group or together complete a five or six membered ring.
  • Ar is preferably a carbocyclic aromatic ring, such as phenyl or naphthyl.
  • any of the nitrogen and carbon containing aromatic rings noted above can be attached to the nitrogen atom of formula II through a ring carbon atom. In this instance, the resulting compound satisfies both formulae I and II. Any of a wide variety of aliphatic groups can be selected.
  • the simplest contemplated aliphatic groups are alkyl groups, preferably those containing from 1 to 10 carbon atoms and most preferably from 1 to 6 carbon atoms. Any functional substituent of the alkyl group known to be compatible with silver halide precipitation can be present. It is also contemplated to employ cyclic aliphatic substituents exhibiting 5 or 6 membered rings, such as cycloalkane, cycloalkene and aliphatic heterocyclic rings, such as those containing oxygen and/or nitrogen hetero atoms. Cyclopentyl, cyclohexyl, pyrrolidinyl, piperidinyl, furanyl and similar heterocyclic rings are specifically contemplated.
  • Selection of preferred restraining agents and their useful concentrations can be accomplished by the following selection procedure:
  • the compound being considered for use as a restraining agent is added to a silver chloride emulsion consisting essentially of cubic grains with a mean grain edge length of 0.3 ⁇ m.
  • the emulsion is 0.2 M in sodium acetate, has a pCl of 2.1, and has a pH that is at least one unit greater than the pKa of the compound being considered.
  • the emulsion is held at 75°C with the restraining agent present for 24 hours.
  • the compound introduced is performing the function of a restraining agent.
  • the significance of sharper edges of intersection of the ⁇ 100 ⁇ crystal faces lies in the fact that grain edges are the most active sites on the grains in terms of ions reentering the dispersing medium.
  • the restraining agent is acting to restrain the emergence of non- ⁇ 100 ⁇ crystal faces, such as are present, for example, at rounded edges and corners.
  • Optimum restraining agent activity occurs when the new grain population is a tabular grain population in which the tabular grains are bounded by ⁇ 100 ⁇ major crystal faces.
  • the emulsions of the invention can be chemically sensitized with active gelatin as illustrated by T. H. James, The Theory of the Photographic Process , 4th Ed., Macmillan, 1977, pp. 67-76, or with sulfur, selenium, tellurium, gold, platinum, palladium, iridium, osmium, rhenium or phosphorus sensitizers or combinations of these sensitizers, such as at pAg levels of from 5 to 10, pH levels of from 5 to 8 and temperatures of from 30 to 80°C, as illustrated by Research Disclosure , Vol. l20, April, 1974, Item l2008, Research Disclosure , Vol.
  • Patent 3,984,249 by low pAg (e.g., less than 5), high pH (e.g., greater than 8) treatment, or through the use of reducing agents such as stannous chloride, thiourea dioxide, polyamines and amineboranes as illustrated by Allen et al U.S. Patent 2,983,609, Oftedahl et al Research Disclosure , Vol. l36, August, 1975, Item l3654, Lowe et al U.S. Patents 2,5l8,698 and 2,739,060, Roberts et al U.S. Patents 2,743,l82 and 'l83, Chambers et al U.S. Patent 3,026,203 and Bigelow et al U.S. Patent 3,36l,564.
  • reducing agents such as stannous chloride, thiourea dioxide, polyamines and amineboranes as illustrated by Allen et al U.S. Patent 2,983,609, Oftedahl e
  • Chemical sensitization can take place in the presence of spectral sensitizing dyes as described by Philippaerts et al U.S. Patent 3,628,960, Kofron et al U.S. Patent 4,439,520, Dickerson U.S. Patent 4,520,098, Maskasky U.S. Patent 4,435,501, Ihama et al U.S. Patent 4,693,965 and Ogawa U.S. Patent 4,791,053. Chemical sensitization can be directed to specific sites or crystallographic faces on the silver halide grain as described by Haugh et al U.K. Patent Application 2,038,792A and Mifune et al published European Patent Application EP 302,528.
  • the sensitivity centers resulting from chemical sensitization can be partially or totally occluded by the precipitation of additional layers of silver halide using such means as twin-jet additions or pAg cycling with alternate additions of silver and halide salts as described by Morgan U.S. Patent 3,917,485, Becker U.S. Patent 3,966,476 and Research Disclosure , Vol. 181, May, 1979, Item 18155.
  • the chemical sensitizers can be added prior to or concurrently with the additional silver halide formation. Chemical sensitization can take place during or after halide conversion as described by Hasebe et al European Patent Application EP 273,404. In many instances epitaxial deposition onto selected tabular grain sites (e.g., edges or corners) can either be used to direct chemical sensitization or to itself perform the functions normally performed by chemical sensitization.
  • the emulsions of the invention can be spectrally sensitized with dyes from a variety of classes, including the polymethine dye class, which includes the cyanines, merocyanines, complex cyanines and merocyanines (i.e., tri-, tetra- and polynuclear cyanines and merocyanines), styryls, merostyryls, streptocyanines, hemicyanines, arylidenes, allopolar cyanines and enamine cyanines.
  • the polymethine dye class which includes the cyanines, merocyanines, complex cyanines and merocyanines (i.e., tri-, tetra- and polynuclear cyanines and merocyanines), styryls, merostyryls, streptocyanines, hemicyanines, arylidenes, allopolar cyanines and enamine cyanines.
  • the cyanine spectral sensitizing dyes include, joined by a methine linkage, two basic heterocyclic nuclei, such as those derived from quinolinium, pyridinium, isoquinolinium, 3H-indolium, benzindolium, oxazolium, thiazolium, selenazolinium, imidazolium, benzoxazolium, benzothiazolium, benzoselenazolium, benzotellurazolium, benzimidazolium, naphthoxazolium, naphthothiazolium, naphthoselenazolium, naphtotellurazolium, thiazolinium, dihydronaphthothiazolium, pyrylium and imidazopyrazinium quaternary salts.
  • two basic heterocyclic nuclei such as those derived from quinolinium, pyridinium, isoquinolinium, 3H-indolium, benzin
  • the merocyanine spectral sensitizing dyes include, joined by a methine linkage, a basic heterocyclic nucleus of the cyanine-dye type and an acidic nucleus such as can be derived from barbituric acid, 2-thiobarbituric acid, rhodanine, hydantoin, 2-thiohydantoin, 4-thiohydantoin, 2-pyrazolin-5-one, 2-isoxazolin-5-one, indan-1,3-dione, cyclohexan-1,3-dione, 1,3-dioxane-4,6-dione, pyrazolin-3,5-dione, pentan-2,4-dione, alkylsulfonyl acetonitrile, benzoylacetonitrile, malononitrile, malonamide, isoquinolin-4-one, chroman-2,4-dione, 5H-furan-2-one
  • One or more spectral sensitizing dyes may be employed. Dyes with sensitizing maxima at wavelengths throughout the visible and infrared spectrum and with a great variety of spectral sensitivity curve shapes are known. The choice and relative proportions of dyes depends upon the region of the spectrum to which sensitivity is desired and upon the shape of the spectral sensitivity curve desired. Dyes with overlapping spectral sensitivity curves will often yield in combination a curve in which the sensitivity at each wavelength in the area of overlap is approximately equal to the sum of the sensitivities of the individual dyes. Thus, it is possible to use combinations of dyes with different maxima to achieve a spectral sensitivity curve with a maximum intermediate to the sensitizing maxima of the individual dyes.
  • Combinations of spectral sensitizing dyes can be used which result in supersensitization--that is, spectral sensitization greater in some spectral region than that from any concentration of one of the dyes alone or that which would result from the additive effect of the dyes.
  • Supersensitization can be achieved with selected combinations of spectral sensitizing dyes and other addenda such as stabilizers and antifoggants, development accelerators or inhibitors, coating aids, brighteners and antistatic agents. Any one of several mechanisms, as well as compounds which can be responsible for supersensitization, are discussed by Gilman, Photographic Science and Engineering , Vol. l8, 1974, pp. 4l8-430.
  • Spectral sensitizing dyes can also affect the emulsions in other ways. For example, spectrally sensitizing dyes can increase photographic speed within the spectral region of inherent sensitivity. Spectral sensitizing dyes can also function as antifoggants or stabilizers, development accelerators or inhibitors, reducing or nucleating agents, and halogen acceptors or electron acceptors, as disclosed in Brooker et al U.S. Patent 2,131,038, Illingsworth et al U.S. Patent 3,50l,3l0, Webster et al U.S. Patent 3,630,749, Spence et al U.S. Patent 3,7l8,470 and Shiba et al U.S. Patent 3,930,860.
  • spectral sensitizing dyes for sensitizing the emulsions of the invention are those found in U.K. Patent 742,112, Brooker U.S. Patents l,846,300, '30l, '302, '303, '304, 2,078,233 and 2,089,729, Brooker et al U.S. Patents 2,l65,338, 2,2l3,238, 2,493,747, '748, 2,526,632, 2,739,964 (Reissue 24,292), 2,778,823, 2,9l7,5l6, 3,352,857, 3,411,916 and 3,431,111, Sprague U.S. Patent 2,503,776, Nys et al U.S.
  • Spectral sensitizing dyes can be added at any stage during the emulsion preparation. They may be added at the beginning of or during precipitation as described by Wall, Photographic Emulsions , American Photographic Publishing Co., Boston, 1929, p. 65, Hill U.S. Patent 2,735,766, Philippaerts et al U.S. Patent 3,628,960, Locker U.S. Patent 4,183,756, Locker et al U.S. Patent 4,225,666 and Research Disclosure , Vol. 181, May, 1979, Item 18155, and Tani et al published European Patent Application EP 301,508. They can be added prior to or during chemical sensitization as described by Kofron et al U.S.
  • the dyes can be mixed in directly before coating as described by Collins et al U.S. Patent 2,912,343. Small amounts of iodide can be adsorbed to the emulsion grains to promote aggregation and adsorption of the spectral sensitizing dyes as described by Dickerson cited above.
  • Postprocessing dye stain can be reduced by the proximity to the dyed emulsion layer of fine high-iodide grains as described by Dickerson.
  • the spectral-sensitizing dyes can be added to the emulsion as solutions in water or such solvents as methanol, ethanol, acetone or pyridine; dissolved in surfactant solutions as described by Sakai et al U.S. Patent 3,822,135; or as dispersions as described by Owens et al U.S. Patent 3,469,987 and Japanese published Patent Application (Kokai) 24185/71.
  • the dyes can be selectively adsorbed to particular crystallographic faces of the emulsion grain as a means of restricting chemical sensitization centers to other faces, as described by Mifune et al published European Patent Application 302,528.
  • the spectral sensitizing dyes may be used in conjunction with poorly adsorbed luminescent dyes, as described by Miyasaka et al published European Patent Applications 270,079, 270,082 and 278,510.
  • stabilizers and antifoggants can be employed, such as halide ions (e.g., bromide salts); chloropalladates and chloropalladites as illustrated by Trivelli et al U.S. Patent 2,566,263; water-soluble inorganic salts of magnesium, calcium, cadmium, cobalt, manganese and zinc as illustrated by Jones U.S. Patent 2,839,405 and Sidebotham U.S. Patent 3,488,709; mercury salts as illustrated by Allen et al U.S. Patent 2,728,663; selenols and diselenides as illustrated by Brown et al U.K.
  • halide ions e.g., bromide salts
  • chloropalladates and chloropalladites as illustrated by Trivelli et al U.S. Patent 2,566,263
  • water-soluble inorganic salts of magnesium, calcium, cadmium, cobalt, manganese and zinc as illustrated by Jones
  • Patent l,336,570 and Pollet et al U.K. Patent l,282,303 quaternary ammonium salts of the type illustrated by Allen et al U.S. Patent 2,694,7l6, Brooker et al U.S. Patent 2,131,038, Graham U.S. Patent 3,342,596 and Arai et al U.S. Patent 3,954,478; azomethine desensitizing dyes as illustrated by Thiers et al U.S. Patent 3,630,744; isothiourea derivatives as illustrated by Herz et al U.S. Patent 3,220,839 and Knott et al U.S.
  • Patent 2,5l4,650 thiazolidines as illustrated by Scavron U.S. Patent 3,565,625; peptide derivatives as illustrated by Maffet U.S. Patent 3,274,002; pyrimidines and 3-pyrazolidones as illustrated by Welsh U.S. Patent 3,161,515 and Hood et al U.S. Patent 2,75l,297; azotriazoles and azotetrazoles as illustrated by Baldassarri et al U.S. Patent 3,925,086; azaindenes, particularly tetraazaindenes, as illustrated by Heimbach U.S. Patent 2,444,605, Knott U.S. Patent 2,933,388, Williams U.S.
  • Patent 3,202,5l2 Research Disclosure , Vol. l34, June, 1975, Item l3452, and Vol. l48, August, 1976, Item 14851, and Nepker et al U.K. Patent l,338,567; mercaptotetrazoles, -triazoles and -diazoles as illustrated by Kendall et al U.S. Patent 2,403,927, Kennard et al U.S. Patent 3,266,897, Research Disclosure , Vol. 116, December, 1973, Item 11684, Luckey et al U.S. Patent 3,397,987 and Salesin U.S. Patent 3,708,303; azoles as illustrated by Peterson et al U.S.
  • High-chloride emulsions can be stabilized by the presence, especially during chemical sensitization, of elemental sulfur as described by Miyoshi et al European published Patent Application EP 294,149 and Tanaka et al European published Patent Application EP 297,804 and thiosulfonates as described by Nishikawa et al European published Patent Application EP 293,917.
  • useful stabilizers for gold sensitized emulsions are water-insoluble gold compounds of benzothiazole, benzoxazole, naphthothiazole and certain merocyanine and cyanine dyes, as illustrated by Yutzy et al U.S. Patent 2,597,9l5, and sulfinamides, as illustrated by Nishio et al U.S. Patent 3,498,792.
  • tetraazaindenes particularly in combination with Group VIII noble metals or resorcinol derivatives, as illustrated by Carroll et al U.S. Patent 2,7l6,062, U.K. Patent l,466,024 and Habu et al U.S. Patent 3,929,486; quaternary ammonium salts of the type illustrated by Piper U.S. Patent 2,886,437; water-insoluble hydroxides as illustrated by Maffet U.S. Patent 2,953,455; phenols as illustrated by Smith U.S. Patents 2,955,037 and '038; ethylene diurea as illustrated by Dersch U.S.
  • Patent 3,582,346 barbituric acid derivatives as illustrated by Wood U.S. Patent 3,6l7,290; boranes as illustrated by Bigelow U.S. Patent 3,725,078; 3-pyrazolidinones as illustrated by Wood U.K. Patent 1,158,059 and aldoximines, amides, anilides and esters as illustrated by Butler et al U.K. Patent 988,052.
  • the emulsions can be protected from fog and desensitization caused by trace amounts of metals such as copper, lead, tin, iron and the like by incorporating addenda such as sulfocatechol-type compounds, as illustrated by Kennard et al U.S. Patent 3,236,652; aldoximines as illustrated by Carroll et al U.K. Patent 623,448 and meta - and polyphosphates as illustrated by Draisbach U.S. Patent 2,239,284, and carboxylic acids such as ethylenediamine tetraacetic acid as illustrated by U.K. Patent 691,715.
  • addenda such as sulfocatechol-type compounds, as illustrated by Kennard et al U.S. Patent 3,236,652; aldoximines as illustrated by Carroll et al U.K. Patent 623,448 and meta - and polyphosphates as illustrated by Draisbach U.S. Patent 2,239,284, and carboxylic acids such as ethylene
  • stabilizers useful in layers containing synthetic polymers of the type employed as vehicles and to improve covering power are monohydric and polyhydric phenols as illustrated by Forsgard U.S. Patent 3,043,697; saccharides as illustrated by U.K. Patent 897,497 and Stevens et al U.K. Patent 1,039,471, and quinoline derivatives as illustrated by Dersch et al U.S. Patent 3,446,6l8.
  • stabilizers useful in protecting the emulsion layers against dichroic fog are addenda such as salts of nitron as illustrated by Barbier et al U.S. Patents 3,679,424 and 3,820,998; mercaptocarboxylic acids as illustrated by Willems et al U.S. Patent 3,600,l78; and addenda listed by E. J. Birr, Stabilization of Photographic Silver Halide Emulsions , Focal Press, London, 1974, pp. l26-2l8.
  • stabilizers useful in protecting emulsion layers against development fog are addenda such as azabenzimidazoles as illustrated by Bloom et al U.K. Patent 1,356,142 and U.S. Patent 3,575,699, Rogers U.S. Patent 3,473,924 and Carlson et al U.S. Patent 3,649,267; substituted benzimidazoles, benzothiazoles, benzotriazoles and the like as illustrated by Brooker et al U.S. Patent 2,131,038, Land U.S. Patent 2,704,72l, Rogers et al U.S.
  • Patent 3,265,498 mercapto-substituted compounds, e.g., mercaptotetrazoles, as illustrated by Dimsdale et al U.S. Patent 2,432,864, Rauch et al U.S. Patent 3,081,170, Weyerts et al U.S. Patent 3,260,597, Grasshoff et al U.S. Patent 3,674,478 and Arond U.S. Patent 3,706,557; isothiourea derivatives as illustrated by Herz et al U.S. Patent 3,220,839, and thiodiazole derivatives as illustrated by von Konig U.S. Patent 3,364,028 and von Konig et al U.K. Patent 1,186,441.
  • mercapto-substituted compounds e.g., mercaptotetrazoles, as illustrated by Dimsdale et al U.S. Patent 2,432,864, Rauch et al U.S. Patent
  • the emulsion layers can be protected with antifoggants such as monohydric and polyhydric phenols of the type illustrated by Sheppard et al U.S. Patent 2,165,421; nitro-substituted compounds of the type disclosed by Rees et al U.K. Patent l,269,268; poly(alkylene oxides) as illustrated by Valbusa U.K. Patent 1,151,914, and mucohalogenic acids in combination with urazoles as illustrated by Allen et al U.S. Patents 3,232,76l and 3,232,764, or further in combination with maleic acid hydrazide as illustrated by Rees et al U.S. Patent 3,295,980.
  • antifoggants such as monohydric and polyhydric phenols of the type illustrated by Sheppard et al U.S. Patent 2,165,421; nitro-substituted compounds of the type disclosed by Rees et al U.K. Patent l,269
  • addenda can be employed such as parabanic acid, hydantoin acid hydrazides and urazoles as illustrated by Anderson et al U.S. Patent 3,287,l35, and piazines containing two symmetrically fused 6-member carbocyclic rings, especially in combination with an aldehyde-type hardening agent, as illustrated in Rees et al U.S. Patent 3,396,023.
  • Kink desensitization of the emulsions can be reduced by the incorporation of thallous nitrate as illustrated by Overman U.S. Patent 2,628,l67; compounds, polymeric lattices and dispersions of the type disclosed by Jones et al U.S. Patents 2,759,82l and '822; azole and mercaptotetrazole hydrophilic colloid dispersions of the type disclosed by Research Disclosure , Vol. 116, December, 1973, Item 11684; plasticized gelatin compositions of the type disclosed by Milton et al U.S. Patent 3,033,680; water-soluble interpolymers of the type disclosed by Rees et al U.S.
  • Patent 3,536,49l polymeric lattices prepared by emulsion polymerization in the presence of poly(alkylene oxide) as disclosed by Pearson et al U.S. Patent 3,772,032, and gelatin graft copolymers of the type disclosed by Rakoczy U.S. Patent 3,837,86l.
  • pressure desensitization and/or increased fog can be controlled by selected combinations of addenda, vehicles, hardeners and/or processing conditions as illustrated by Abbott et al U.S. Patent 3,295,976, Barnes et al U.S. Patent 3,545,97l, Salesin U.S. Patent 3,708,303, Yamamoto et al U.S. Patent 3,6l5,619, Brown et al U.S. Patent 3,623,873, Taber U.S. Patent 3,67l,258, Abele U.S. Patent 3,79l,830, Research Disclosure , Vol. 99, July, 1972, Item 9930, Florens et al U.S.
  • Patent 3,843,364 Priem et al U.S. Patent 3,867,l52, Adachi et al U.S. Patent 3,967,965 and Mikawa et al U.S. Patents 3,947,274 and 3,954,474.
  • latent-image stabilizers can be incorporated, such as amino acids, as illustrated by Ezekiel U.K. Patents l,335,923, l,378,354, l,387,654 and 1,391,672, Ezekiel et al U.K. Patent 1,394,371, Jefferson U.S. Patent 3,843,372, Jefferson et al U.K. Patent 1,412,294 and Thurston U.K. Patent l,343,904; carbonyl-bisulfite addition products in combination with hydroxybenzene or aromatic amine developing agents as illustrated by Seiter et al U.S.
  • Patent 3,424,583 cycloalkyl-1,3-diones as illustrated by Beckett et al U.S. Patent 3,447,926; enzymes of the catalase type as illustrated by Matejec et al U.S. Patent 3,600,l82; halogen-substituted hardeners in combination with certain cyanine dyes as illustrated by Kumai et al U.S. Patent 3,88l,933; hydrazides as illustrated by Honig et al U.S. Patent 3,386,83l; alkenyl benzothiazolium salts as illustrated by Arai et al U.S.
  • Patent 3,954,478 hydroxy-substituted benzylidene derivatives as illustrated by Thurston U.K. Patent l,308,777 and Ezekiel et al U.K. Patents l,347,544 and l,353,527; mercapto-substituted compounds of the type disclosed by Sutherns U.S. Patent 3,519,427; metal-organic complexes of the type disclosed by Matejec et al U.S. Patent 3,639,l28; penicillin derivatives as illustrated by Ezekiel U.K.
  • Patent l,389,089 propynylthio derivatives of benzimidazoles, pyrimidines, etc., as illustrated by von Konig et al U.S. Patent 3,910,791; combinations of iridium and rhodium compounds as disclosed by Yamasue et al U.S. Patent 3,901,713; sydnones or sydnone imines as illustrated by Noda et al U.S. Patent 3,88l,939; thiazolidine derivatives as illustrated by Ezekiel U.K. Patent l,458,197 and thioether-substituted imidazoles as illustrated by Research Disclosure , Vol. l36, August, 1975, Item 13651.
  • the tabular grains that they produce, and their further use in photography can take any convenient conventional form.
  • Substitution for conventional emulsions of the same or similar silver halide composition is generally contemplated, with substitution for silver halide emulsions of differing halide composition, particularly tabular grain emulsions, being also feasible in many types of photographic applications.
  • the low levels of native blue sensitivity of the high chloride ⁇ 100 ⁇ tabular grain emulsions of the invention allows the emulsions to be employed in any desired layer order arrangement in multicolor photographic elements, including any of the layer order arrangements disclosed by Kofron et al U.S. Patent 4,439,520, the disclosure of which is here incorporated by reference, both for layer order arrangements and for other conventional features of photographic elements containing tabular grain emulsions.
  • Conventional features are further illustrated by the following incorporated by reference disclosures:
  • Photographic elements containing high chloride ⁇ 100 ⁇ tabular grain emulsions according to this invention can be imagewise-exposed with various forms of energy which encompass the ultraviolet and visible (e.g., actinic) and infrared regions of the electromagnetic spectrum, as well as electron-beam and beta radiation, gamma ray, X-ray, alpha particle, neutron radiation and other forms of corpuscular and wave-like radiant energy in either noncoherent (random phase) forms or coherent (in phase) forms as produced by lasers. Exposures can be monochromatic, orthochromatic or panchromatic.
  • ultraviolet and visible (e.g., actinic) and infrared regions of the electromagnetic spectrum as well as electron-beam and beta radiation, gamma ray, X-ray, alpha particle, neutron radiation and other forms of corpuscular and wave-like radiant energy in either noncoherent (random phase) forms or coherent (in phase) forms as produced by lasers.
  • Exposures can be monochromatic, orthochromat
  • Imagewise exposures at ambient, elevated or reduced temperatures and/or pressures including high- or low-intensity exposures, continuous or intermittent exposures, exposure times ranging from minutes to relatively short durations in the millisecond to microsecond range and solarizing exposures, can be employed within the useful response ranges determined by conventional sensitometric techniques, as illustrated by T. H. James, The Theory of the Photographic Process , 4th Ed., Macmillan, 1977, Chapters 4, 6, 17, 18 and 23.
  • the invention can be better appreciated by reference to the following examples.
  • APMT is employed to designate 1-(3-acetamidophenyl)-5-mercaptotetrazole.
  • low methionine gelatin is employed, except as otherwise indicated, to designate gelatin that has been treated with an oxidizing agent to reduce its methionine content to less than 30 micromoles per gram.
  • DW is employed to indicate distilled water.
  • mppm is employed to indicate molar parts per million.
  • Rsens is in some instances employed to indicate relative sensitivity.
  • This example demonstrates the preparation of an ultrathin tabular grain silver iodochloride emulsion satisfying the requirements of this invention.
  • a 2030 mL solution containing 1.75% by weight low methionine gelatin, 0.011 M sodium chloride and 1.48 x 10 ⁇ 4 M potassium iodide was provided in a stirred reaction vessel.
  • the contents of the reaction vessel were maintained at 40°C and the pCl was 1.95.
  • the mixture was then held 10 minutes with the temperature remaining at 40°C. Following the hold, a 1.0 M silver nitrate solution and a 1.0 M NaCl solution were then added simultaneously at 2 mL/min for 40 minutes with the pCl being maintained at 1.95.
  • the resulting emulsion was a tabular grain silver iodochloride emulsion containing 0.5 mole percent iodide, based on silver. Fifty percent of total grain projected area was provided by tabular grains having ⁇ 100 ⁇ major faces having an average ECD of 0.84 mm and an average thickness of 0.037 ⁇ m, selected on the basis of an aspect ratio rank ordering of all ⁇ 100 ⁇ tabular grains having a thickness of less than 0.3 ⁇ m and a major face edge length ratio of less than 10.
  • the selected tabular grain population had an average aspect ratio (ECD/t) of 23 and an average tabularity (ECD/t2) of 657. The ratio of major face edge lengths of the selected tabular grains was 1.4.
  • tabular grains having ⁇ 100 ⁇ major faces and aspect ratios of at least 7.5. These tabular grains had a mean ECD of 0.75 ⁇ m, a mean thickness of 0.045 ⁇ m, a mean aspect ratio of 18.6 and a mean tabularity of 488.
  • This emulsion demonstrates the importance of iodide in the precipitation of the initial grain population (nucleation).
  • This emulsion was precipitated identically to that of Example 1, except no iodide was intentionally added.
  • the resulting emulsion consisted primarily of cubes and very low aspect ratio rectangular grains ranging in size from about 0.1 to 0.5 ⁇ m in edge length. A small number of large rods and high aspect ratio ⁇ 100 ⁇ tabular grains were present, but did not constitute a useful quantity of the grain population.
  • the sensitized emulsions were coated onto cellulose acetate film support.
  • the coating format was an emulsion layer comprised of 200 mg/ft2 (21.5 mg/dm2) of the tabular silver chloride emulsion dispersed in 500 mg/ft2 (53.8 mg/dm2) of gelatin; an overcoat comprised of 100 mg/ft2 (10.8 mg/dm2) gelatin and a hardener, bis(vinylsulfonylmethyl)ether at a level of 0.5% by weight, based on total gelatin.
  • the coated photographic elements were evaluated for reciprocity response by giving them a series of calibrated (total energy) exposures ranging from 1/10 of a second to 10 seconds.
  • the exposed film was processed for 6 minutes in a hydroquinone-ElonTM ( p -N-methylaminophenol hemisulfate) developer.
  • This example demonstrates the usefulness of dopant D-2 added during spectral sensitization by means of a pCl cycle which is comprised of sequential addition of chloride ion, D-2, and silver ion.
  • the introduction of the dopant in the pCl cycle produces an emulsion with improved LIRF behavior as compared to either an emulsion that is spectrally sensitized without use of the dopant or the pCl cycle or an emulsion that is spectrally sensitized with the pCl cycle, but with the dopant omitted, where the emulsions are otherwise the same.
  • Emulsion S-1 was spectrally sensitized by treating a portion with 550 mg per mole of silver of blue spectral sensitizing dye Dye SS-1 followed by heat digestion. APMT was added thereafter at an amount of 90 mg per silver mole. This represents the control emulsion.
  • a final example was prepared in which a pCl cycle without dopant was performed to demonstrate the effect of the 2 mole % cycle, free of any dopant effects.
  • Table III summarizes the photographic results of various amounts of D-2 added via a pCl cycle technique. Table III Ex. 3 Part # cycle before/after dye D-2 micro- gram. per mole Speed LIRF 365 nm whitelight 3/1 none none 160 160 30 3/2 after none 171 158 23 3/3 after 15 164 151 23 3/4 after 50 150 134 8 3/5 after 100 150 134 5 3/6 before 15 169 160 18 3/7 before 50 161 152 15 3/8 before 100 161 152 13
  • This example demonstrates the usefulness of dopants D-1, D-2 and D-3 in reducing LIRF when added via a pCl cycle technique to the spectral and chemical sensitization of emulsions S-2 and S-3.
  • This example demonstrates the effectiveness of iridium to reduce LIRF when incorporated during precipitation with a silver bromide Lippmann emulsion.
  • the host high chloride ⁇ 100 ⁇ tabular grain emulsion employed Emulsion S-3, described in Example 4.
  • Lippmann silver bromide emulsions (of approximately 0.08 ⁇ m edge length) were prepared with and without incorporated dopants.
  • Table V lists the Lippmann emulsions used and the dopant type and amount contained in each emulsion. By blending doped and undoped Lippmann emulsions a variety of dopant concentrations were available for incorporation onto the host AgCl ⁇ 100 ⁇ T-grain emulsion.
  • Portions of host emulsion S-3 were spectrally and chemically sensitized by treating each portion with 550 mg per mole of silver of blue spectral sensitizing dye Dye SS-1 followed by a heat digestion. Two mg per silver mole of a colloidal gold sulfide reagent were added followed by heat digestion for 30 minutes at 60°C. Thereafter, the temperature was adjusted to 40°C and 90 mg per silver mole of APMT were added. The resulting parts represent the undoped emulsions provided for comparison.
  • Another comparative emulsion was prepared in a similar manner to that described above, except that 2 mole % of an undoped Lippmann silver bromide emulsion were added after the colloidal gold sulfide and heat digestion. Once the Lippmann emulsion was added an additional heat digestion of 10 minutes at 60°C was performed. Then the temperature was lowered to 40°C, and 90 mg per silver mole of APMT was added.
  • This comparative example was provided to demonstrate the effect of an undoped Lippman bromide on the S-3 host emulsion.
  • This example demonstrates an emulsion according to the invention in which 90% of the total grain projected area is comprised of tabular grains with ⁇ 100 ⁇ major faces and aspect ratios of greater than 7.5.
  • a 2030 mL solution containing 3.52% by weight low methionine gelatin, 0.0056 M sodium chloride and 1.48 x 10 ⁇ 4 M potassium iodide was provided in a stirred reaction vessel.
  • the contents of the reaction vessel were maintained at 40°C and the pCl was 2.25.
  • the mixture was then held 10 minutes with the temperature remaining at 40°C. Following the hold, a 0.5 M silver nitrate solution and a 0.5 M NaCl solution were then added simultaneously at 8 mL/min for 40 minutes with the pCl being maintained at 2.35. The 0.5 M AgNO3 solution and the 0.5 M NaCl solution were then added simultaneously with a ramped linearly increasing flow from 8 mL per minute to 16 mL per minute over 130 minutes with the pCl maintained at 2.35.
  • the resulting emulsion was a tabular grain silver iodochloride emulsion containing 0.06 mole percent iodide, based on silver.
  • Fifty percent of total grain projected area was provided by tabular grains having ⁇ 100 ⁇ major faces having an average ECD of 1.86 ⁇ m and an average thickness of 0.082 ⁇ m, selected on the basis of an aspect ratio rank ordering of all ⁇ 100 ⁇ tabular grains having a thickness of less than 0.3 ⁇ m and a major face edge length ratio of less than 10.
  • the selected tabular grain population had an average aspect ratio (ECD/t) of 24 and an average tabularity (ECD/t2) of 314.
  • the ratio of major face edge lengths of the selected tabular grains was 1.2.
  • tabular grains having ⁇ 100 ⁇ major faces and aspect ratios of at least 7.5. These tabular grains had a mean ECD of 1.47 ⁇ m, a mean thickness of 0.086 ⁇ m, a mean aspect ratio of 17.5 and a mean tabularity of 222.
  • This example demonstrates an emulsion prepared similarly as the emulsion of Example 3, but an initial 0.08 mole percent iodide and a final 0.04% iodide.
  • a 2030 mL solution containing 3.52% by weight low methionine gelatin, 0.0056 M sodium chloride and 3.00 x 10 ⁇ 5 M potassium iodide was provided in a stirred reaction vessel.
  • the contents of the reaction vessel were maintained at 40°C and the pCl was 2.25.
  • the mixture was then held 10 minutes with the temperature remaining at 40°C. Following the hold, a 0.5 M silver nitrate solution and a 0.5 M sodium chloride solution were then added simultaneously at 8 mL/min for 40 minutes with the pCl being maintained at 2.95.
  • the resulting emulsion was a tabular grain silver iodochloride emulsion containing 0.04 mole percent iodide, based on silver. Fifty percent of the total grain projected area was provided by tabular grains having ⁇ 100 ⁇ major faces having an average ECD of 0.67 ⁇ m and an average thickness of 0.035 ⁇ m, selected on the basis of an aspect ratio rank ordering of all ⁇ 100 ⁇ tabular grains having a thickness of less than 0.3 ⁇ m and a major face edge length ratio of less than 10.
  • the selected tabular grain population had an average aspect ratio (ECD/t) of 20 and an average tabularity (ECD/t2) of 651. The ratio of major face edge lengths of the selected tabular grains was 1.9.
  • tabular grains having ⁇ 100 ⁇ major faces and aspect ratios of at least 7.5. These tabular grains had a mean ECD of 0.63 ⁇ m, a mean thickness of 0.036 ⁇ m, a mean aspect ratio of 18.5 and a mean tabularity of 595.
  • This example demonstrates an emulsion in which the initial grain population contained 6.0 mole percent iodide and the final emulsion contained 1.6% iodide.
  • a 2030 mL solution containing 3.52% by weight low methionine gelatin, 0.0056 M sodium chloride and 3.00 x 10 ⁇ 5 M potassium iodide was provided in a stirred reaction vessel.
  • the contents of the reaction vessel were maintained at 40°C and the pCl was 2.25.
  • the mixture was then held 10 minutes with the temperature remaining at 40°C. Following the hold, a 1.00 M silver nitrate solution and a 1.00 M sodium chloride solution were then added simultaneously at 2 mL/min for 40 minutes with the pCl being maintained at 2.35.
  • the resulting emulsion was a tabular grain silver iodochloride emulsion containing 1.6 mole percent iodide, based on silver.
  • Fifty percent of total grain projected area was provided by tabular grains having ⁇ 100 ⁇ major faces having an average ECD of 0.57 ⁇ m and an average thickness of 0.036 ⁇ m, selected on the basis of an aspect ratio rank ordering of all ⁇ 100 ⁇ tabular grains having a thickness of less than 0.3 ⁇ m and a major face edge length ratio of less than 10.
  • the selected tabular grain population had an average aspect ratio (ECD/t) of 16.2 and an average tabularity (ECD/t2) of 494.
  • the ratio of major face edge lengths of the selected tabular grains was 1.9.
  • tabular grains having ⁇ 100 ⁇ major faces and aspect ratios of at least 7.5. These tabular grains had a mean ECD of 0.55 ⁇ m, a mean thickness of 0.041 ⁇ m, a mean aspect ratio of 14.5 and a mean tabularity of 421.
  • This example demonstrates an ultrathin high aspect ratio ⁇ 100 ⁇ tabular grain emulsion in which 2 mole percent iodide is present in the initial population and additional iodide is added during growth to make the final iodide level 5 mole percent.
  • a 2030 mL solution containing 1.75% by weight low methionine gelatin, 0.0056 M sodium chloride and 1.48 x 10 ⁇ 4 M potassium iodide was provided in a stirred reaction vessel.
  • the contents of the reaction vessel were maintained at 40°C and the pCl was 2.2.
  • the mixture was then held 10 minutes with the temperature remaining at 40°C. Following the hold, a 1.00 M silver nitrate solution and a 1.00 M sodium chloride solution were then added simultaneously at 8 mL/min while a 3.375 X 10 ⁇ 2 M potassium iodide was simultaneously added at 14.6 mL/min for 10 minutes with the pCl being maintained at 2.35.
  • the resulting emulsion was a tabular grain silver iodochloride emulsion containing 5 mole percent iodide, based on silver. Fifty percent of total grain projected area was provided by tabular grains having ⁇ 100 ⁇ major faces having an average ECD of 0.58 ⁇ m and an average thickness of 0.030 ⁇ m, selected on the basis of an aspect ratio rank ordering of all ⁇ 100 ⁇ tabular grains having a thickness of less than 0.3 ⁇ m and a major face edge length ratio less than 10.
  • the selected tabular grain population had an average aspect ratio (ECD/t) of 20.6 and an average tabularity (ECD/t2) of 803. The ratio of major face edge lengths of the selected tabular grains was 2.
  • This example demonstrates a high aspect ratio ⁇ 100 ⁇ tabular emulsion where 1 mole percent iodide is present in the initial grain population and 50 mole percent bromide is added during growth to make the final emulsion 0.3 mole percent iodide, 36 mole percent bromide and 63.7 mole percent chloride.
  • a 2030 mL solution containing 3.52% by weight low methionine gelatin, 0.0056 M sodium chloride and 1.48 x 10 ⁇ 4 M potassium iodide was provided in a stirred reaction vessel.
  • the contents of the reaction vessel were maintained at 40°C and the pCl was 2.25.
  • the resulting emulsion was a tabular grain silver iodobromochloride emulsion containing 0.27 mole percent iodide and 36 mole percent bromide, based on silver, the remaining halide being chloride.
  • Fifty percent of total grain projected area was provided by tabular grains having ⁇ 100 ⁇ major faces having an average ECD of 0.4 ⁇ m and an average thickness of 0.032 ⁇ m, selected on the basis of an aspect ratio rank ordering of all ⁇ 100 ⁇ tabular grains having a thickness of less than 0.3 ⁇ m and a major face edge length ratio of less than 10.
  • the selected tabular grain population had an average aspect ratio (ECD/t) of 12.8 and an average tabularity (ECD/t2) of 432.
  • the ratio of major face edge lengths of the selected tabular grains was 1.9. Seventy one percent of total grain projected area was made up of tabular grains having ⁇ 100 ⁇ major faces and aspect ratios of at least 7.5. These tabular grains had a mean ECD of 0.38 mm, a mean thickness of 0.034 ⁇ m, a mean aspect ratio of 11.3 and a mean tabularity of 363.
  • This example demonstrates the preparation of an emulsion satisfying the requirements of the invention employing phthalated gelatin as a peptizer.
  • the mixture was then held 10 minutes with the temperature remaining at 40°C. Following the hold, the silver and salt solutions were added simultaneously with a linearly accelerated flow from 3.0 mL/min to 9.0 mL/min over 15 minutes with the pCl of the mixture being maintained at 2.7.
  • the resulting emulsion was a high aspect ratio tabular grain silver iodochloride emulsion.
  • Fifty percent of total grain projected area was provided by tabular grains having ⁇ 100 ⁇ major faces having an average ECD of 0.37 ⁇ m and an average thickness of 0.037 ⁇ m, selected on the basis of an aspect ratio rank ordering of all ⁇ 100 ⁇ tabular grains having a thickness of less than 0.3 ⁇ m and a major face edge length ratio of less than 10.
  • the selected tabular grain population had an average aspect ratio (ECD/t) of 10 and an average tabularity (ECD/t2) of 330.
  • Seventy percent of total grain projected area was made up of tabular grains having ⁇ 100 ⁇ major faces and aspect ratios of at least 7.5. These tabular grains had a mean ECD of 0.3 ⁇ m, a mean thickness of 0.04 ⁇ m, and a mean tabularity of 210.
  • Electron diffraction examination of the square and rectangular surfaces of the tabular grains confirmed major face ⁇ 100 ⁇ crystallographic orientation.
  • This example demonstrates the preparation of an emulsion satisfying the requirements of the invention employing an unmodified bone gelatin as a peptizer.
  • the mixture was then held for 5 minutes during which a 5000 mL solution that is 16.6 g/L of low methionine gelatin was added and the pH was adjusted to 6.5 and the pCl to 2.25. Following the hold, the silver and salt solutions were added simultaneously with a linearly accelerated flow from 10 mL/min to 25.8 mL/min over 63 minutes with the pCl of the mixture being maintained at 2.25.
  • the resulting emulsion was a high aspect ratio tabular grain silver iodochloride emulsion containing 0.01 mole % iodide. About 65% of the total projected grain area was provided by tabular grains having an average diameter of 1.5 ⁇ m and an average thickness of 0.18 ⁇ m.
  • This example compares the photographic performance of a ⁇ 100 ⁇ silver chloride tabular emulsion according to the invention to a silver chloride cubic grain emulsion of similar average grain volume.
  • Emulsion A Silver iodochloride tabular emulsion with ⁇ 100 ⁇ major faces
  • a 6090 ml solution containing 3.52% by weight of low methionine gelatin, 0.0056 M sodium chloride and 1.48 x 10 ⁇ 4 potassium iodide was provided in a stirred reaction vessel at 40°C. While the solution was vigorously stirred, 90 mL of 2.0 M silver nitrate and 90 mL of a 1.99 M sodium chloride and 0.01 M potassium iodide solution were added simultaneously at a rate of 180 mL/min each. The mixture was then held for 10 minutes with the temperature remaining at 40°C.
  • a 0.5 M silver nitrate solution and a 0.5 M sodium chloride solution were added simultaneously at 24 mL/min for 40 minutes followed by a linear acceleration from 24 mL/min to 48 mL/min over 130 minutes, while maintaining the pCl at 2.35.
  • the pCl was then adjusted to 1.30 with sodium chloride then washed using ultrafiltration to a pCl of 2.0 then adjusted to a pCl of 1.65 with sodium chloride.
  • the resulting emulsion was a tabular grain silver chloride emulsion contained 0.06 mole percent iodide and had a mean equivalent circular grain diameter of 1.45 ⁇ m and a mean grain thickness of 0.13 ⁇ m.
  • Emulsion A An optimum green light sensitization was found for Emulsion A by conducting numerous small scale finishing experiments where the level of sensitizing dye, sodium thiosulfate pentahydrate, aurous dithiosulfate dihydrate and the hold time at 65°C were varied.
  • the optimum finish was as follows: to a 0.5 mole portion of Emulsion A melted at 40°C and well stirred, 0.800 mmol/mole of green light sensitizing dye A was added followed by a 20 minute hold. To this was added 0.10 mg/mole of sodium thiosulfate pentahydrate and 0.20 mg/mole of sodium aurous dithiosulfate dihydrate. The temperature was then increased to 65°C over 9 minutes and then held for 4 minutes at 65°C and rapidly cooled to 40°C.
  • Emulsion B Silver chloride cubic grain emulsion (Control)
  • a monodisperse silver chloride cube with a cubic edge length of 0.59 ⁇ m was prepared by simultaneous addition of 3.75 M silver nitrate and 3.75 M sodium chloride to a well stirred solution containing 8.2 g/l of sodium chloride, 28.2 g/l of bone gelatin and 0.212 g/liter of 1,8-dithiadioctanediol while maintaining the temperature at 68.3°C and the pCl at 1.0.
  • the temperature was reduced to 40°C and the emulsion was washed by ultrafiltration to a pCl of 2.0, then adjusted to a pCl of 1.65 with sodium chloride.
  • Emulsion A An optimum green light sensitization was found in the same manner as described for Emulsion A.
  • the conditions for the optimum were as follows: to a 0.05 mole quantity of Emulsion B melted at 40°C and well stirred, 0.2 mmol/mole of sensitizing dye A was added followed by a 20 minute hold. To this was added 0.25 mg/mole of sodium thiosulfate pentahydrate and 0.50 mg/mole of sodium aurous dithiosulfate dihydrate. The temperature was then increased to 65°C over 9 minutes and held for 10 minutes followed by rapid cooling to 40°C.
  • Each of the sensitized emulsions was coated on antihalation support at 0.85 g/m2 of silver along with 1.1 g/m2 of cyan dye-forming coupler C and 2.7 g/m2 of gelatin. This was overcoated with 1.6 g/m2 of gelatin and hardened with 1.7 weight percent, based on total gelatin, of bis(vinylsulfonylmethyl)ether.
  • the coatings were evaluated for intrinsic sensitivity by exposing for 0.02 seconds in a step wedge sensitometer with the 365 nm line of a mercury vapor lamp as the light source.
  • Sensitivity to green light was measured by exposing the coatings for 0.02 seconds using a step wedge sensitometer with a 3000°K tungsten lamp filtered to simulate a Daylight V light source and filtered to transmit only green and red light by a Kodak Wratten TM 9 filter (transmitting wavelengths longer than 450 nm).
  • the coatings were processed using the Kodak Flexicolor TMC-41 color negative process, described in Brit. J. Photog. Annual 1988, p196-198 , and the dye density was measured using status M red filtration.
  • the photographic results are summarized in Table VII.
  • Table VII shows that for intrinsic sensitivity as measured by the 365 line exposure, both Emulsions A and B are very similar as would be expected based on their similar grain volume. Comparing the green light sensitivity as measured by the Wratten TM 9 exposures shows that the tabular emulsion is 2.9 times more sensitive to green light than the cubic emulsion. This clearly shows the advantage of the tabular morphology.
  • This example describes the sensitization and photographic performance of a ⁇ 100 ⁇ silver chloride tabular emulsion and a silver chloride cubic emulsion of similar average grain volume sensitized using gold sulfide and a blue spectral sensitizing dye, and compared in low silver coatings on a resin coated paper support.
  • This emulsion was prepared in an identical fashion to the ⁇ 100 ⁇ silver chloride tabular emulsion described in Example 13.
  • This emulsion was prepared in a similar fashion to the cubic emulsion described in Example 13, except the ripener 1,8-dithiadioctanediol was omitted and flow rates and precipitation time were adjusted to achieve the same size emulsion.
  • Both emulsions were sensitized to blue light using the following procedures.
  • a quantity of each emulsion was melted at 40°C, 660 mg/mole Ag of sensitizing dye B was added to the ⁇ 100 ⁇ tabular emulsion and 220 mg/mole of the same dye was added to the cubic emulsion based on their specific surface area, followed by a 20 minute hold.
  • 2.0 mg/mole of aurous sulfide was added to each emulsion followed by a 5 minute hold.
  • the temperature was then raised to 60°C and held for 30 minutes after which 90 mg/mole of APMT was added and the emulsion was chill set.
  • each of the sensitized emulsions was coated on resin coated paper support at 0.28 g/m2 of silver along with 1.1 g/m2 of yellow dye forming coupler B and 0.82 g/m2 of gelatin.
  • the coatings were evaluated for intrinsic sensitivity by exposing for 0.1 seconds in a step wedge sensitometer with the 365 nm line of a mercury vapor lamp as the light source. Sensitivity to white light was measured by exposing the coatings for 0.1 seconds using a step wedge sensitometer with a 3000°K tungsten lamp.
  • the coatings were processed using a standard RA-4 color paper process as described in Research Disclosure, Vol. 308, p.933, 1989. Dye density was measured using standard reflection geometry and status A filtration .
  • Table VIII Emulsion 365 line exposure 3000°K Tungsten exposure Dmin Rsens contrast Dmin Rsens contrast ⁇ 100 ⁇ tabular 0.08 98 2.53 .08 154 2.53 cubic 0.11 100 2.64 .11 100 2.64
  • Table VIII shows that for intrinsic sensitivity as measured by the 365 line exposure, both the cubic and the tabular emulsion are similar in sensitivity, as would be expected based on their similar grain volume. Comparing the white light sensitivity as measured by the 3000°K tungsten exposures shows that the tabular emulsion is about 50% more sensitive to blue light than the cubic emulsion.
  • This example shows how bromide can be added at the end of the precipitation or during the finish to produce emulsions with surface halide structure and/or growths. These emulsions show good photographic performance.
  • Emulsion A (Invention)
  • This emulsion was prepared identically to the ⁇ 100 ⁇ tabular emulsion described in Example 13. A quantity of this emulsion was then melted at 40°C and 1200 mg/mole of potassium bromide was rapidly added. 0.6 mmol of green sensitizing dye A per mole of emulsion was then added followed by a 20 minute hold. 1.0 mg/mole of sodium thiosulfate pentahydrate and 1.3 mg/mole of potassium tetrachloroaurate were then added followed by a temperature ramp to 60°C and a 10 minute hold. The emulsion was then cooled to 40°C and 70 mg/mole of APMT was added and the emulsion was chill set. Examination of the crystals by scanning electron microscopy revealed that the edges of the crystal had been roughened by the bromide deposition and some surface roughening was also present.
  • Emulsion B (Invention)
  • This emulsion illustrates the precipitation and sensitization of a ⁇ 100 ⁇ silver chloride tabular emulsion where potassium bromide was added during the final step of the precipitation to form an emulsion whereby the majority of the grains have epitaxial deposits located at 3 or 4 of the 4 available tabular grain corners.
  • a 1536 mL solution containing 3.52% by weight low methionine gelatin, 0.0056 M sodium chloride and 2.34 X 10 ⁇ 4 M potassium iodide was provided in a stirred reaction vessel at 40°C and pH 5.74. While this solution was vigorously stirred, 30 mL of 2.0 M silver nitrate and 30 mL of 2.0 M sodium chloride were added simultaneously at a rate of 60 mL/min each. This achieved grain nucleation.
  • the mixture was then held for 10 seconds after which a 0.5 M silver nitrate and a 0.5 M sodium chloride solution were added simultaneously at 5.3 mL/min for 60 minutes with the pCl maintained at 2.35.
  • the silver nitrate and sodium chloride solutions were then added using linearly accelerated flow rates from 5.3 mL/min to 15.6 mL/min over 150 minutes.
  • the pCl was then adjusted to 1.55 with sodium chloride and 25g of phthalated deionized gel was added and dissolved. The pH was then reduced to 3.85 and the stirring was stopped to allow the coagulum to settle. The supernatant was discarded and distilled water was added back to the coagulum to bring it to its original volume at the end of the precipitation. Stirring was resumed and the pH was adjusted back to 5.36 and the pCl was 2.45.
  • the pH was adjusted to 5.8 and 25g of phthalated deionized gel was added and dissolved. The pH was reduced to 3.85 and stirring was stopped to allow the coagulum to settle. The supernatant was removed, 27g of low methionine gel was added and the emulsion weight was raised to 800g with distilled water. The pH was adjusted to 5.77 and the pCl to 1.65 with 1.0 M sodium chloride solution.
  • the resulting emulsion had a mean equivalent circular diameter of 1.67mm and a mean grain thickness of 0.135mm.
  • the halide composition was 93.964% silver chloride, 6.0% silver bromide and 0.0036% silver iodide. Seventy-five percent of the grains had three or more minor edges with epitaxial deposits.
  • a 0.15 mole quantity of emulsion was melted at 40°C with stirring. To this was added 0.70 mmol/mole of green sensitizing dye A followed by a 20 minute hold. To this was added 1.0 mg/mole of sodium thiosulfate pentahydrate and 1.3 mg/mole of potassium tetrachloroaurate. The temperature was then increased to 60°C over 12 minutes and held for 5 minutes followed by rapid cooling to 40°C. 70 mg/mole of APMT was then added and the emulsion was chill set.
  • This example illustrates the precipitation and sensitization of a ⁇ 100 ⁇ silver chloride tabular emulsion where potassium bromide was added during the final step of the precipitation to form an emulsion where the majority of the grains had epitaxial deposits located at only 1 or 2 of the minor edges.
  • a 1536 mL solution containing 3.52% by weight low methionine gelatin, 0.0056 M sodium chloride and 2.34 X 10 ⁇ 4 M potassium iodide was provided in a stirred reaction vessel at 40°C and pH 5.74. While this solution was vigorously stirred, 30 mL of 2.0 M silver nitrate and 30 mL of 2.0 M sodium chloride were added simultaneously at a rate of 60 mL/min each. This achieved grain nucleation.
  • the mixture was then held for 10 seconds after which a 0.5 M silver nitrate and a 0.5 M sodium chloride solution were added simultaneously at 8.0 mL/min for 40 minutes with the pCl maintained at 2.35.
  • the silver nitrate and sodium chloride solutions were then added using linearly accelerated flow rates from 8.0 mL/min to 16.1 mL/min over 130 minutes.
  • the pCl was then adjusted to 1.65 by running the sodium chloride solution at 20 mL/min for 8.0 min. This was followed by a 10 minute hold. The pCl was then increased back to 2.15 by running the silver nitrate solution at 5.0 mL/min for 27.7 min. This was followed by the addition of a 1.5 M potassium bromide solution at 2.0 mL/min over 20 minutes bringing the pCl to 1.70.
  • the resulting emulsion had a mean equivalent circular diameter of 1.65mm and a mean grain thickness of 0.14mm.
  • the halide composition was 93.964% silver chloride, 6.0% silver bromide and 0.0036% silver iodide. Examination of the emulsion by scanning electron microscopy showed that 97 percent of the grains had epitaxial depositions visible on two or fewer of the four available host tabular grain corners.
  • the sensitization was identical to that used in Example B, except the level of sodium thiosulfate pentahydrate and potassium tetrachloroaurate were increased by 50%.
  • Emulsion D (Control)
  • This emulsion was composed of silver chloride cubic grains and was precipitated identically to the cubic emulsion in Example 13 and is of similar grain volume to the three tabular emulsions in this example.
  • This emulsion was sensitized as follows: a quantity was melted at 40°C and 500 mg/mole of potassium bromide was added followed by 0.2 mg/mole of sensitizing dye A and a 20 minute hold. To this was added 0.25 mg/mole of sodium thiosulfate pentahydrate and 0.50 mg/mole of sodium aurous dithiosulfate dihydrate followed by a temperature ramp to 65°C and a 12 minute hold. The emulsion was then quickly chilled.
  • Each of the sensitized emulsions was coated on antihalation support at 0.85 g/m2 of silver along with 1.1 g/m2 of cyan dye forming coupler C and 2.7 g/m2 of gelatin. This was overcoated with 1.6 g/m2 of gelatin and hardened with bis(vinyl-sulfonylmethyl)ether at 1.75% of the total coated gelatin weight.
  • the coatings were evaluated for intrinsic sensitivity by exposing for 0.02 seconds in a step wedge sensitometer with the 365 nm line of a mercury vapor lamp as the source.
  • Sensitivity to green light was measured by exposing the coatings for 0.02 seconds using a step wedge sensitometer with a 3000°K tungsten lamp filtered to simulate a Daylight V source and filtered to transmit only light with wavelengths longer than 400 nm by a Kodak Wratten TM 2B filter.
  • the coatings were then processed using a Kodak Flexicolor TM C-41 color negative process.
  • the dye density was measured using status M red filtration.
  • Table IX Emulsion WrattenTM 2B exposure 365 line exposure Dmin Rsens contrast Dmin Rsens contrast Emulsion A .14 200 2.22 .12 60 1.87 Emulsion B .13 275 2.05 .14 141 1.89 Emulsion C .12 245 2.36 .13 79 2.65 Emulsion D (control) .14 100 2.82 .18 100 2.48
  • Table IX shows all of the ⁇ 100 ⁇ tabular grain emulsion examples are at least 2 times more sensitive to a white light exposure than the similarly sensitized cubic grain emulsion even though emulsion A and C showed less intrinsic sensitivity to the 365 mercury line exposure.
  • TBA+ tributylammonium
  • the resulting grain mixture was examined by optical and electron microscopy.
  • the emulsion contained a population of small cubes of approximately 0.2 ⁇ m edge length, large nontabular grains, and tabular grains with square or rectangular major faces. In terms of numbers of grains the small grains were overwhelmingly predominant. The tabular grains accounted for no more than 25 percent of the total grain projected area of the emulsion.
  • the mean thickness of the tabular grain population was determined from edge-on views obtained using an electron microscope. A total of 26 tabular grains were measured and found to have a mean thickness of 0.38 ⁇ m. Of the 26 tabular grains measured for thickness, only one had a thickness of less than 0.3 ⁇ m, the thickness of that one tabular grain being 0.25 ⁇ m.
  • This example has as its purpose to demonstrate successful preparation of an emulsion satisfying the requirements of the invention employing commercially available deionized gelatin as a starting material.
  • a 4.0 M silver nitrate and a 4.0 M sodium chloride solution were added for 30 seconds at a rate consuming 5 percent of the total silver.
  • the emulsion was then held at 62°C for 10 minutes followed by the addition of 5000 g of a solution containing 1.6 percent of the deionized gelatin. This was followed by simultaneous addition of the silver nitrate and sodium chloride with the flow rates linearly increased by a factor of 2.58 over 70 minutes with the pAg maintained at 6.37.
  • the total amount of silver iodochloride precipitated was 4.745 moles.
  • tabular grains exhibited an average ECD of 1.65 ⁇ m, an average thickness of 0.165 ⁇ m, and an average aspect ratio of 10.
  • tabular grains When the preparation procedure described above was repeated with calcium acetate substituted for calcium chloride hydrate, greater than 85 percent of total grain projected area was accounted for by tabular grains.
  • the tabular grains exhibited an average ECD of 1.5 ⁇ m, an average thickness of 0.16 ⁇ m, and an average aspect ratio of 9.4.
  • magnesium, aluminum or iron ions were substituted for calcium ions in the dispersing medium, emulsions satisfying the requirements of the invention were also obtained.
  • a 6090 mL solution containing 3.52% by weight of low methionine gelatin, 0.0056 M sodium chloride and 1.48 x 10 ⁇ 4 potassium iodide was provided in a stirred reaction vessel at 40°C. While the solution was vigorously stirred, 90 mL of 2.0 M silver nitrate and 90 mL of a 1.99 M sodium chloride and 0.01 M potassium iodide solution were added simultaneously at a rate of 180 mL/min each. The mixture was then held for 10 minutes with the temperature remaining at 40°C.
  • a 1.0 M silver nitrate solution and a 1.0 M sodium chloride solution were added simultaneously at 12 mL/min for 40 minutes followed by a linear acceleration from 12 mL/min to 33.7 mL/min over 233.2 minutes, while maintaining the pCl at 2.25.
  • the pCl was then adjusted to 1.30 with sodium chloride then washed using ultrafiltration to a pCl of 2.0 then adjusted to a pCl of 1.65 with sodium chloride.
  • the resulting emulsion was a tabular grain silver chloroiodide emulsion contained 0.03 mole percent iodide with a mean equivalent circular grain diameter of 1.51 ⁇ m and a mean thickness of 0.22 ⁇ m.
  • the resulting average aspect ratio was 6.9 and the average tabularity was 31.
  • a 1536 mL solution containing 3.52% by weight of low methionine (hydrogen peroxide treated) gelatin, 0.0056 M sodium chloride, 2.34 x 10 ⁇ 4 M potassium iodide, and 0.3 mL of a polyethylene glycol antifoamant was provided in a stirred reaction vessel at 40°C. While the solution was vigorously stirred, 30 mL of 2.0 M silver nitrate and 30 mL of a 2.0 M sodium chloride solution were added simultaneously at a rate of 60 mL/min each. The mixture was then held for 10 seconds.
  • a 0.5 M silver nitrate solution and a 0.5 M sodium chloride solution were added simultaneously at 8 mL/min for 40 minutes with the pCl maintained at 2.25.
  • the pCl was then adjusted to 1.65 with 1.0 M sodium chloride.
  • the 0.5 M silver nitrate and the 0.5 M sodium chloride were then each added at a linearly increasing the flow rate, commencing at 8 mL/min and increasing at a rate of 0.0615 mL/min while maintaining pCl at 1.65.
  • After 90 minutes microscopic observation of the emulsion showed an equivalent circular diameter of 0.9 ⁇ m with a mean grain thickness of 0.17 mum. The average aspect ratio at this point was 5.3 and the tabularity was 31.
  • the mixture was then held for 5 minutes during which 7000 mL of distilled water were added and the temperature was raised to 65°C, while the pCl was adjusted to 2.15 and the pH to 6.5. Following the hold, the size of the resulting grains was increased through growth using a dual-zone process.
  • a solution of 0.67 M silver nitrate was premixed with a 0.67 M solution of sodium chloride and a solution of 0.5 percent by weight bone gelatin at a pH of 6.5, in a continuous reactor with a total volume of 30 mL, which was well-mixed.
  • the effluent from this premixing reactor was then added to the original reaction vessel, which during this step acted as a growth reactor.
  • the fine crystals from the continuous reactor were ripened onto the original crystals through Ostwald ripening.
  • the total suspension volume of the growth reactor during this growth step was maintained constant at 13.5 L using ultrafiltration.
  • the flow rates of the 0.67 M silver nitrate solution and the 0.67 M sodium chloride solution were linearly increased from 20 to 80 mL/min, 150 mL/min and 240 mL/min in 25 minute intervals.
  • the flow rate of the 0.5 percent gelatin reactant was maintained constant at 500 mL/min.
  • the continuous reactor in which these reactants were premixed was kept at 30°C and a pCl of 2.45, while the growth reactor was maintained at a temperature of 65°C, a pCl of 2.15, and a pH of 6.5.
  • Silver iodochloride nuclei were formed in a 30 mL well-mixed, continuous reactor by mixing a 0.447 M silver nitrate solution (at 100 mL/min) with a 0.487 M sodium chloride and 0.00377 M potassium iodide solution (at 100 mL/min) and a 2.0 percent by weight bone gelatin solution (at 1 L/min) at a pCl of 2.3 and a temperature of 40°C. The resulting mixture containing the nuclei was transferred to a stirred semi-batch reactor for 1.5 min.
  • the semi-batch reactor was maintained at 65°C and a constant volume of 13.5 L (using ultrafiltration) and was initially at a pCl of 2.15, a pH of 6.5 and a bone gelatin concentration of 0.37 percent by weight. During the nuclei transfer from the continuous reactor to the semi-batch reactor the pCl of the latter was maintained at 2.15 by the addition of a 1 M sodium chloride solution.
  • the flow rates of the 0.67 M silver nitrate solution and the 0.67 M sodium chloride solution were linearly increased from 20 to 80 mL/min, 150 mL/min and 240 mL/min in 25 minute intervals.
  • the flow rate of the 0.5 percent gelatin reactant was maintained constant at 500 mL/min.
  • the continuous reactor in which these reactants were premixed was kept at 30°C and a pCl of 2.45, while the growth reactor was maintained at a temperature of 65°C, a pCl of 2.15, and a pH of 6.5.

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EP94104411A 1993-03-22 1994-03-21 Mit Oligomeren modifizierte Emulsionen tafelförmiger Körner Withdrawn EP0617317A1 (de)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0618493A2 (de) * 1993-04-02 1994-10-05 Fuji Photo Film Co., Ltd. Farbphotographisches photoempfindliches Silberhalogenidmaterial
US5665530A (en) * 1994-08-30 1997-09-09 Fuji Photo Film Co., Ltd. Silver halide emulsion and photographic material using the same
US5707793A (en) * 1995-04-19 1998-01-13 Fuji Photo Film Co., Ltd. Silver halide emulsion and silver halide photographic material using the same

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4063951A (en) * 1974-12-19 1977-12-20 Ciba-Geigy Ag Manufacture of tabular habit silver halide crystals for photographic emulsions
US5024931A (en) * 1990-01-05 1991-06-18 Eastman Kodak Company Photographic emulsions sensitized by the introduction of oligomers
JPH03252649A (ja) * 1990-03-02 1991-11-11 Fuji Photo Film Co Ltd ハロゲン化銀写真用乳剤

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4063951A (en) * 1974-12-19 1977-12-20 Ciba-Geigy Ag Manufacture of tabular habit silver halide crystals for photographic emulsions
US5024931A (en) * 1990-01-05 1991-06-18 Eastman Kodak Company Photographic emulsions sensitized by the introduction of oligomers
EP0436249A1 (de) * 1990-01-05 1991-07-10 Eastman Kodak Company Photographische Emulsionen, die durch die Zugabe von Oligomeren sensibilisiert werden
JPH03252649A (ja) * 1990-03-02 1991-11-11 Fuji Photo Film Co Ltd ハロゲン化銀写真用乳剤

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Week 9151, Derwent World Patents Index; AN 91374154 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0618493A2 (de) * 1993-04-02 1994-10-05 Fuji Photo Film Co., Ltd. Farbphotographisches photoempfindliches Silberhalogenidmaterial
EP0618493A3 (de) * 1993-04-02 1995-08-02 Fuji Photo Film Co Ltd Farbphotographisches photoempfindliches Silberhalogenidmaterial.
US5814439A (en) * 1993-04-02 1998-09-29 Fuji Photo Film Co., Ltd. Silver halide color photographic photo-sensitive material
US5665530A (en) * 1994-08-30 1997-09-09 Fuji Photo Film Co., Ltd. Silver halide emulsion and photographic material using the same
US5707793A (en) * 1995-04-19 1998-01-13 Fuji Photo Film Co., Ltd. Silver halide emulsion and silver halide photographic material using the same

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