Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C7/00—Multicolour photographic processes or agents therefor; Regeneration of such processing agents; Photosensitive materials for multicolour processes
  • G03C7/30—Colour processes using colour-coupling substances; Materials therefor; Preparing or processing such materials
  • G03C7/3022—Materials with specific emulsion characteristics, e.g. thickness of the layers, silver content, shape of AgX grains
• • 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
  • G03C1/08—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
  • G03C1/06—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
  • G03C1/22—Methine and polymethine dyes with an even number of CH groups
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/0051—Tabular grain emulsions
  • G03C2001/0055—Aspect ratio of tabular grains in general; High aspect ratio; Intermediate aspect ratio; Low aspect ratio
• • 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
  • G03C1/035—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein characterised by the crystal form or composition, e.g. mixed grain
  • G03C2001/03594—Size of the grains
• • 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
• • 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
  • G03C2200/11—Blue-sensitive layer
• • 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
  • G03C2200/53—Red-sensitive layer
• • 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
  • G03C7/00—Multicolour photographic processes or agents therefor; Regeneration of such processing agents; Photosensitive materials for multicolour processes
  • G03C7/30—Colour processes using colour-coupling substances; Materials therefor; Preparing or processing such materials
  • G03C7/305—Substances liberating photographically active agents, e.g. development-inhibiting releasing couplers
• • 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
  • G03C7/00—Multicolour photographic processes or agents therefor; Regeneration of such processing agents; Photosensitive materials for multicolour processes
  • G03C7/30—Colour processes using colour-coupling substances; Materials therefor; Preparing or processing such materials
  • G03C7/305—Substances liberating photographically active agents, e.g. development-inhibiting releasing couplers
  • G03C7/30541—Substances liberating photographically active agents, e.g. development-inhibiting releasing couplers characterised by the released group

Definitions

• the invention relates to color photographic elements comprising radiation sensitive tabular grain silver halide emulsion layers.
• 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 apsect 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.
• the overwhelming majority of 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 ⁇ crystallographic 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.
• Patent 4,399,215 produced the first tabular grain silver chloride emulsion.
• the tabular grains were of the twinned type, exhibiting major faces of threefold symmetry lying in ⁇ 111 ⁇ crystallographic planes.
• An ammoniacal double-jet precipitation technique was employed.
• the thicknesses of the tabular grains were high compared to contemporaneous silver bromide and bromoiodide tabular grain emulsions because the ammonia ripening agent thickened the tabular grains.
• To achieve ammonia ripening it was also necessary to precipitate the emulsions at a relatively high pH, which is known to produce elevated minimum densities (fog) in high chloride emulsions.
• both bromide and iodide ions were excluded from the tabular grains early in their formation.
• 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
• 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.
• 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) .
• image dye-forming compounds in color photographic elements has been known for many years. Typically these compounds are used in reactive association with silver halide emulsion layers in such elements. During the development process the dye-forming compound reacts with oxidized developing agent to form a dye. The dye density that can be obtained for a specific quantity of developed silver is greatly influenced by the morphology of the silver halide grains in the emulsion layer since larger, more sensitive silver halide grains tend to provide lower dye density than smaller,, less light sensitive grains. Accordingly, there is a continuing need for combinations of silver halide emulsions and image dye-forming compounds which can provide both high sensitivity and high dye density formation.
• beneficial effects can be achieved when silver halide emulsion layers are used in color photographic elements comprising compounds that contain photographically useful groups that are released upon reaction with oxidized developing agent. Such compounds are used to achieve such desired effects as an interlayer or interimage effect or an image accutance effect.
• These compounds can be simply referred to as "photographically useful group-releasing compounds", as more fully described hereinafter, and are illustrated in U.S. Patent Nos. 4,248,962; 4,409,323 and 4,861,701 and European Patent Application 354,532.
• An example of such photographically useful group-releasing compounds are the Development Inhibitor Releasing (DIR) compounds which are known in the photographic art.
• DIR Development Inhibitor Releasing
• DIR compounds can release development inhibitors during photographic processing and such inhibitors can be used to provide a variety of photographic effects such as decreasing gamma which can be used to control curve shape.
• Development Inhibitor Releasing compounds have limited utility with cubic silver halide emulsions having high chloride contents because such compounds tend to have little impact on latitude or gamma when they are used with such emulsions.
• DIR compounds often cause speed losses with such emulsions.
• Maskasky U.S. Serial No. filed concurrently herewith as a continuation-in-part of U.S. Serial No. 955,010, filed Oct. 1, 1992, which is in turn a continuation-in-part of U.S. Serial No. 764,868, filed Sept. 24, 1991, titled HIGH TABULARITY HIGH CHLORIDE EMULSIONS WITH INHERENTLY STABLE GRAIN FACES, commonly assigned, hereinafter referred to as Maskasky III, discloses high aspect ratio tabular grain high chloride emulsions containing tabular grains that are internally free of iodide and that have ⁇ 100 ⁇ major faces. In a preferred form, Maskasky III employs an organic compound containing a nitrogen atom with a resonance stabilized p electron pair to favor formation of ⁇ 100 ⁇ faces. House, House, Hartsell and Black U.S. Serial No.
• each commonly assigned, titled PROCESSES OF PREPARING TABULAR GRAIN EMULSIONS discloses processes of preparing emulsions containing tabular grains bounded by ⁇ 100 ⁇ major faces of which tabular grains bounded by ⁇ 100 ⁇ major faces account for 50 percent of total grain projected area selected on the criteria of adjacent major face edge ratios of less than 10 and thicknesses of less than 0.3 mm and internally at their nucleation site contain iodide and at least 50 mole percent chloride, comprised of the steps of (1) introducing silver and halide salts into the 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 and (2) following nucleation completing grain growth under conditions that maintain the ⁇ 100 ⁇ major faces of the tabular grains until the tabular grains exhibit an average aspect ratio of greater
• Puckett U.S. Serial No. ___ filed concurrently herewith and commonly assigned, titled OLIGOMER MODIFIED TABULAR GRAIN EMULSIONS discloses radiation sensitive emulsions and processes for their preparation. At least 50 percent of total grain projected area is accounted for by high chloride tabular grains bounded by ⁇ 100 ⁇ major faces having adjacent edge ratios of less than 10, each having an aspect ratio of at least 2 and 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.
• COORDINATION COMPLEX LIGAND MODIFIED TABULAR GRAIN EMULSIONS discloses emulsions containing tabular grains bounded by ⁇ 100 ⁇ major faces accounting for 50 percent of total grain projected area selected on the criteria of adjacent major face edge ratios of less than 10 and thicknesses of less than 0.3 m and having higher aspect ratios than any remaining tabular grains satisfying these criteria (1) have an average aspect ratio of greater than 8 and (2) internally at their nucleation site contain iodide and at least 50 mole percent chloride.
• the tabular grain contain non-halide coordination complex ligands.
• Budz, Ligtenberg and Roberts U.S. Serial No. filed concurrently herewith and commonly assigned, titled DIGITAL IMAGING WITH TABULAR GRAIN EMULSIONS, discloses digitally imaging photographic elements containing tabular grain emulsions comprised of a dispersing medium and silver halide grains containing at least 50 mole percent chloride based, on silver. At least 50 percent of total grain projected area is accounted for by tabular grains bounded by ⁇ 100 ⁇ major faces having adjacent edge ratios of less than 10, each having an aspect ratio of at least 2.
• tabular grain emulsions comprised of a dispersing medium, silver halide grains containing at least 50 mole percent chloride based on silver and at least one selected antifoggant or stabilizer. At least 50 percent of total grain projected area is accounted for by tabular grains bounded by ⁇ 100 ⁇ major faces having adjacent edge ratios of less than 10, each having an aspect ratio of at least 2.
• Ma ' skasky U.S. Serial No. filed concurrently herewith and commonly assigned, titled MODERATE ASPECT RATIO TABULAR GRAIN HIGH CHLORIDE EMULSIONS WITH INHERENTLY STABLE GRAIN FACES, discloses an emulsion containing a grain population internally free of iodide at the grain nucleation site and comprised of at least 50 mole percent chloride. At least 50 percent of the grain population projected area is accounted for by ⁇ 100 ⁇ tabular grains each having an aspect ratio of at least 2 and together having an average aspect ratio of up to 7.5.
• this invention is directed to a color photographic element having a support bearing at least one radiation sensitive emulsion layer comprising dispersing medium and silver halide grains, and having in reactive association an image dye-forming compound. At least 50 percent of the total grain projected area is accounted for by tabular grains that are bounded by100 major faces having adjacent edge ratios of less than 10 and each having an aspect ratio of at least 2.
• the emulsion layer is also in reactive association with a compound that contains a photographically useful group and is capable of reacting with oxidized developing agent to thereby release such group.
• a photographically useful group such as development inhibitor groups that are released upon reaction with oxidized developing agent, provide desirable reductions in gamma simultaneously with large increases in latitude which are completely unexpected in light of the results obtained with prior art silver halide emulsions comprising comparable cubic silver halide grains.
• this invention provides excellent flexibility in choosing a desired specific photographic activity since a wide variety of compounds which release photographically useful groups can be used in the practice of this invention.
• suitable photographically useful groups include development inhibitors, development accelerators, bleach inhibitors, bleach accelerators, electron transfer agents or couplers such as competing couplers.
• 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 invention extends to 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.
• Figure 1 is a shadowed photomicrograph of carbon grain replicas of a representative emulsion prepared according to Illustrative Emulsion Preparation, Preparation I, which is a typical emulsion useful in the color photographic elements of this invention.
• Figure 2 is a shadowed photomicrograph of carbon grain replicas of a control emulsion prepared according to Illustrative Emulsion Preparation, Preparation II.
• 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 angle of illumination (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 mm and, optimally, less than 0.2 mm. 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 eaach exhibit a grain thickness of less than 0.3 mm or less than 0.2 mm.
• 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 mm or 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 accounting for at least 50 percent of total grain projected area is provided by tabular grains also exhibiting 0.2 mm.
• 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 an average thickness of less than 0.06 mm.
• 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.
• Emulsions according to the invention can be prepared in which the tabular grain population has a mean thickness down to 0.02 mm and even 0.01 mm.
• 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.
• 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.
• T is tabularity
• AR is aspect ratio
• ECD is equivalent circular diameter in micrometers
• 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 mm are contemplated, although average ECD's in most photographic applications rarely exceed 6 mm.
• ECD's for photographic utility average ECD's of less than 10 mm are contemplated, although average ECD's in most photographic applications rarely exceed 6 mm.
• ultrathin tabular grain emulsions satisfying the requirements of the invention it is possible to provide intermediate aspect ratios with ECD's of the tabular grain population of 0.10 mm 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.
• 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 mm.
• 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.
• 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.
• cubic grain nuclei being formed having one or more screw dislocations in one or more of the cubic crystal faces.
• the cubic crystal faces that contain at least one screw dislocation thereafter accept silver halide at an accelerated rate as compared to the regular cubic crystal faces (i.e., those lacking a screw dislocation) .
• the regular cubic crystal faces i.e., those lacking a screw dislocation
• grain growth on only one face is accelerated, and the resulting grain structure on continued growth is a rod.
• the same result occurs when only two opposite parallel faces of the cubic crystal structure contain screw dislocations.
• any two contiguous cubic crystal faces contain a screw dislocation
• continued growth accelerates growth on both faces and produces a tabular grain structure.
• the tabular grains of the emulsions of this invention are produced by those grain nuclei having two, three or four faces containing screw dislocations.
• 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--!.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.
• 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. Any convenient conventional source of silver and halide ions can be employed during the nucleation step. 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
• 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.
• 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.
• 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 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 thiocyanate ⁇ .
• 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 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.
• 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.
• 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.
• the 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) .
• a nucleation reaction vessel in which the growth stage of grain precipitation occurs
• 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.
• the active- interventions of Mignot to eliminate grain nuclei coalescence can be-either eliminated or moderated. It is also contemplated to enhance limited grain coalescence by employing one or more peptizers that exhibit reduced adhesion to grain surfaces. For example, it is generally recognized that 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.
• 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 iodo- bromochloride emulsions and silver iodochlorobromide emulsions. Dopants, in concentrations of up to 10"2 mole per silver mole and typically less than 10" ⁇ mole per silver mole, can be present in the grains.
• Compounds of metals such as copper, thallium, lead, mercury, bismuth, zinc, cadmium , rhenium, and Group VIII metals (e.g., iron, ruthenium, rhodium, palladium, osmium, iridium, and platinum) can be present during grain precipitation, preferably during the growth stage of precipitation.
• the modification of photographic properties is related to the level and location of the dopant within the grains.
• the metal forms a part of a coordination complex, such as a hexacoordination complex or a tetracoordination complex
• the ligands can also be included within the grains and the ligands can further influence photographic properties.
• Coordination ligands such as halo, aquo, cyano cyanate, thiocyanate, nitrosyl, thionitrosyl, oxo and carbonyl ligands are contemplated and can be relied upon to modify photographic properties.
• 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 p 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 p 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: (I)
• 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 o . 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
• R! and 2 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. By maintaining sharp edges 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. In some instances instead of dissolved silver chloride depositing exclusively onto the edges of the cubic grains a new population of grains bounded by ⁇ 100 ⁇ crystal faces is formed. 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 used in this 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. 120, April, 1974, Item 12008, Research Disclosure, Vol. 134, June, 1975, Item 13452, Sheppard et al U.S.
• Patent 3,565,631 and Oftedahl U.S. Patent 3,901,714 elemental sulfur as described by Miyoshi et al European Patent Application EP 294,149 and Tanaka et al European Patent Application EP 297,804; and thiosulfonates as described by Nishikawa et al European Patent Application EP 293,917.
• the emulsions can be reduction- sensitized—e.g., with hydrogen, as illustrated by Janusonis U.S. Patent 3,891,446 and Babcock et al U.S.
• 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. 136, August, 1975, Item 13654, Lowe et al U.S. Patents 2,518,698 and 2,739,060, Roberts et al U.S. Patents 2,743,182 and '183, Chambers et al U.S. Patent 3,026,203 and Bigelow et al U.S.
• 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. 136, August
• Patent 3,361,564 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 o 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.
• epitaxial deposition onto selected tabular grain sites e.g., edge or corners
• epitaxial deposition onto selected tabular grain sites can either be used to direct chemical sensitization or to itself perform the functions normall performed by chemical sensitization.
• the emulsions can be spectrally sensitized wit dyes from a variety of classes, including the polymethin dye class, which includes the cyanines, merocyanines, complex cyanines and merocyanines (i.e., tri-, tetra- an polynuclear cyanines and merocyanines) , styryls, merostyryls, streptocyanines, hemicyanines, arylidenes, allopolar cyanines and enamine cyanines.
• the polymethin dye class which includes the cyanines, merocyanines, complex cyanines and merocyanines (i.e., tri-, tetra- an 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-l,3-dione, cyclohexan-1,3- dione, l,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 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 spectr 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 equa 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. 18, 1974, pp. 418-430.
• Spectral sensitizing dyes can also affect the emulsions in other ways.
• 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 3,501,310, Webster et al U.S. Patent 3,630,749, Spence et al U.S. Patent 3,718,470 and Shiba et al U.S. Patent 3,930,860.
• 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.
• Patent 4,439,520 Dickerson U.S. Patent 4,520,098, Maskasky U.S. Patent 4,435,501 and Philippaerts et al cited above. They can be added before or during emulsion washing as described by Asami et al published European Patent Application EP 287,100 and Metoki et al published European Patent Application EP 291,399.
• 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
• 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. The following illustrate specific spectral sensitizing dye selections:
• Instability which increases minimum density in negative-type emulsion coatings can be protected against by incorporation of stabilizers, antifoggants, antikinking agents, latent-image stabilizers and similar addenda in the emulsion and contiguous layers prior to coating.
• Most of the antifoggants effective in the emulsions used in this invention can also be used in developers and can be classified under a few general headings, as illustrated by C.E.K. Mees, The Theory of the Photographic Process, 2Nd Ed., Macmillan, 1954, pp. 677-680.
• 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
• Patent 1,336,570 and Pollet et al U.K. Patent 1,282,303 quaternary ammonium salts of the type illustrated by Allen et al U.S. Patent 2,694,716, 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 2,514,650; 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 2,751,297; 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 3,202,512, Research Disclosure, Vol. 134, June, 1975, Item 13452, and Vol.
• High-chloride emulsions can be stabilized by the pre ⁇ ence, especially during chemical sen ⁇ itization, 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 thiosulfonate ⁇ a ⁇ de ⁇ cribed by Ni ⁇ hikawa et al European published Patent Application EP 293,917.
• useful stabilizer ⁇ for gold ⁇ en ⁇ itized 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 2,597,915, and sulfinamides, as illustrated by Nishio et al U.S. Patent 3,498,792.
• u ⁇ eful stabilizers in layers containing poly(alkylene oxides) are tetraazaindene ⁇ , particularly in combination with Group VIII noble metals or resorcinol derivatives, as illu ⁇ trated by Carroll et al U.S. Patent 2,716,062, U.K. Patent 1,466,024 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- in ⁇ oluble hydroxide ⁇ as illustrated by Maffet U.S. Patent 2,953,455; phenols as illustrated by Smith U.S.
• the emulsion ⁇ can be protected from fog and de ⁇ en ⁇ itization cau ⁇ ed by trace amount ⁇ of metal ⁇ 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; aldoximine ⁇ a ⁇ illu ⁇ trated by Carroll et al U.K. Patent 623,448 and meta- and polypho ⁇ phate ⁇ a ⁇ illustrated by Draisbach U.S. Patent 2,239,284, and carboxylic acid ⁇ ⁇ uch a ⁇ ethylenediamine tetraacetic acid a ⁇ 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; aldoximine ⁇ a ⁇ illu ⁇ trated by Carroll et al U.K. Patent 623,448 and meta
• stabilizers useful in layer ⁇ 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 3,446,618.
• stabilizers useful in protecting the emulsion layers against dichroic fog are addenda such a ⁇ salts of nitron as illustrated by Barbier et al U.S.
• stabilizers useful in protecting emul ⁇ ion 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 2,704,721, Rogers et al U.S. Patent 3,265,498; mercapto-substituted compounds, e.g., mercaptotetrazole ⁇ , a ⁇ 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.
• 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-sub ⁇ tituted compounds of the type disclosed by Rees et al U.K. Patent 1,269,268; poly(alkylene oxides) as illu ⁇ trated by Valbusa U.K. Patent 1,151,914, and mucohalogenic acids in combination with urazoles as illustrated by Allen et al U.S.
• antifoggants such as monohydric and polyhydric phenols of the type illustrated by Sheppard et al U.S. Patent 2,165,421; nitro-sub ⁇ tituted compounds of the type disclosed by Rees et al U.K. Patent 1,269,268; poly(alkylene oxides) as illu ⁇ trated by Valbusa U.K. Patent 1,151,914, and mucohalogenic acids in combination with ur
• addenda can be employed such as parabanic acid, hydantoin acid hydrazides and urazole ⁇ a ⁇ illu ⁇ trated by Ander ⁇ on et al U.S. Patent 3,287,135, 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 2,628,167; compounds, polymeric latices and dispersions of the type disclosed by Jones et al U.S. Patents 2,759,821 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 3,536,491 polymeric latices 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 3,837,861.
• 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 3,545,971, Salesin U.S. Patent 3,708,303, Yamamoto et al U.S.
• latent-image stabilizers can be incorporated, such as amino acids, as illustrated by Ezekiel U.K. Patents 1,335,923, 1,378,354, 1,387,654 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 1,343,904; carbonyl-bisulfite addition products in combination with hydroxybenzene or aromatic a ine developing agents as illustrated by Seiter et al U.S.
• Patent 3,424,583 cycloalkyl-l,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 3,600,182; halogen-substituted hardeners in combination with certain cyanine dyes as illustrated by Kumai et al U.S. Patent 3,881,933; hydrazides as illustrated by Honig et al U.S. Patent 3,386,831; 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 1,308,777 and Ezekiel et al U.K. Patents 1,347,544 and 1,353,527; mercapto- substituted compound ⁇ 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 3,639,128; penicillin derivatives as illustrated by Ezekiel U.K. Patent 1,389,089; 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 3,881,939; thiazolidine derivatives as illustrated by Ezekiel U.K. Patent 1,458,197 and thioether-substituted imidazoles as illustrated by .Research Disclosure, Vol. 136, August, 1975, Item 13651.
• Patent 4,439,520 the disclo ⁇ ure of which i ⁇ here incorporated by reference, both for layer order arrangement ⁇ and for other conventional feature ⁇ of photographic.elements containing tabular grain emulsion ⁇ . Conventional feature ⁇ are further illustrated by the following incorporated by reference disclosures:
• a dye image-forming compound is typically a coupler compound, a dye redox releaser compound, a dye developer compound, an oxichromic developer compound, or a bleachable dye or dye precursor compound.
• Dye redox releaser, dye developer, and oxichromic developer compounds useful in color photographic elements that can be employed in image transfer processes are described in The Theory of the Photographic Process, 4th edition, T.H. James, editor, Macmillan, New York, 1977, Chapter 12, Section V, and in Section XXIII of Research Disclosure, December 1989, Item 308119, published by Kenneth Mason Publications, Ltd., Dudley Annex, 12a North Street, Emsworth, Hampshire, POIO 7DQ, United Kingdom.
• Dye compounds useful in color photographic elements employed in dye bleach processes are described in Chapter 12, Section IV, of The Theory of the Photographic Process, 4th edition.
• Preferred dye image-forming compounds are coupler compounds, which react with oxidized color developing agents to form colored products, or dyes.
• a coupler compound contains a coupler moiety COUP, which is combined with the oxidized developer species in the coupling reaction to form the dye structure.
• a coupler compound can additionally contain a group, called a coupling-off group, that is attached to the coupler moiety by a bond that is cleaved upon reaction of the coupler compound with oxidized color developing agent.
• Coupling-off groups can be halogen, such as chloro, bro o, fluoro, and iodo, or organic radicals that are attached to the coupler moieties by atoms such as oxygen, sulfur, nitrogen, phosphorus, and the like.
• a PUG-releasing compound is a compound that contains a photographically useful group and is capable of reacting with an oxidized developing agent to release said group.
• a PUG-releasing compound comprises a carrier moiety and a leaving group, which are linked by a bond that is cleaved upon reaction with oxidized developing agent.
• the leaving group contains the PUG, which can be present either as a preformed species, or as a blocked or precursor species that undergoes further reaction after cleavage of the leaving group from the carrier to produce the PUG.
• the reaction of an oxidized developing agent with a PUG-releasing compound can produce either colored or colorless products.
• Carrier moieties include hydroquinones, catechols, aminophenols, sulfonamidophenols, suifonamidonaphthols, hydrazides, and the like that undergo cross-oxidation by oxidized developing agents.
• a preferred carrier moiety in a PUG-releasing compound is a coupler moiety COUP, which can combine with an oxidized color developer in the cleavage reaction to form a colored species, or dye.
• the carrier moiety is a COUP
• the leaving group is referred to as a coupling-off group.
• the coupling-off group contains the PUG, either as a preformed species or as a blocked or precursor species.
• the coupler moiety can be ballasted or unballasted. It can be monomeric, or it can be part of a dimeric, oligomeric or polymeric coupler, in which case more than one group containing PUG can be contained in the coupler, or it can form part of a bis compound in which the PUG forms part of a link between two coupler moieties.
• the PUG can be any group that is typically made available in a photographic element in an imagewise fashion.
• the PUG can be a photographic reagent or a photographic dye.
• a photographic reagent, which upon release further reacts with components in the photographic element as described herein, is a moiety such as a development inhibitor, a development accelerator, a bleach inhibitor, a bleach accelerator, an electron transfer agent, a coupler (for example, a competing coupler, a dye-forming coupler, or a development inhibitor releasing coupler, a dye precursor, a dye, a developing agent (for example, a competing developing agent, a dye-forming developing agent, or a silver halide developing agent) , a silver complexing agent, a fixing agent, an image toner, a stabilizer, a hardener, a tanning agent, a fogging agent, an ultraviolet radiation absorber, an antifoggant, a nucleator, a chemical or spectral sensitizer, or a desensitizer.
• the PUG can be present in the coupling-off group a ⁇ a preformed specie ⁇ or it can be present in a blocked form or as a precursor.
• the PUG can be, for example, a preformed development inhibitor, or the development inhibiting function can be blocked by being the point of attachment to the carbonyl group bonded to
• a PUG-releasing compound can be described by the formula CAR-(TIME) n -PUG, wherein (TIME) is a linking or timing group, n is 0, 1, or 2, and CAR is a carrier
• Linking group ⁇ when present, are groups such as esters, carbamates, and the like that undergo base-catalyzed cleavage, including intramolecular nucleophilic displacement, thereby releasing PUG.
• n is 2, the (TIME) groups can be the same or different.
• Suitable linking groups which are also known as timing group ⁇ , are shown in U.S. Patent Nos. 5,151,343; 5,051,345; 5,006,448; 4,409,323; 4,248,962; 4,847,185; 4,857,440; 4,857,447; 4,861,701; 5,021,322; 5,026,628, and 5,021,555, all incorporated herein by reference.
• linking groups are p- hydroxphenylmethylene moieties, a ⁇ illu ⁇ trated in the previously mentioned U.S. Patent Nos. 4,409,323; 5,151,343 and 5,006,448, and o-hydroxyphenyl substituted carbamate groups, disclosed in U.S. Patent Nos. 5,151,343
• TIME When TIME is joined to a COUP, it can be bonded at any of the positions from which groups are released from couplers by reaction with oxidized color developing r 35 agent.
• TIME is attached at the coupling position of the coupler moiety so that, upon reaction of the coupler with oxidized color developing agent, TIME, with attached groups, will be released from COUP.
• TIME can also be in a non-coupling position of the coupler moiety ; from which it can be displaced as a result of reaction of the coupler with oxidized color developing agent.
• other groups can be in the coupling position, including conventional coupling off groups.
• the same or different inhibitor moieties from those described in this invention can be used.
• COUP can have TIME and PUG in each of a coupling position and a non-coupling position. Accordingly, compounds useful in this invention can release more than one mole of PUG per mole of coupler.
• TIME can be any organic group which will serve to connect CAR to the PUG moiety and which, after cleavage from CAR, will in turn be cleaved from the PUG moiety.
• This cleavage is preferably by an intramolecular nucleophilic displacement reaction of the type described in, for example, U.S. Patent No. 4,248,962, or by electron transfer along a conjugated chain as described in, for example, U.S. Patent No. 4,409,323.
• the term "intramolecular nucleophilic displacement reaction” refers to a reaction in which a nucleophilic center of a compound reacts directly, or indirectly through an intervening molecule, at another site .on the compound, which is an electrophilic center, to effect displacement of a group or atom attached to the electrophilic center.
• Such compounds have both a nucleophilic group and an electrophilic group spatially related by the configuration of the molecule to promote reactive proximity.
• the nucleophilic group and the electrophilic group are located in the compound so that a cyclic organic ring, or a transient cyclic organic ring, can be easily formed by an intramolecular reaction involving the nucleophilic center and the electrophilic center.
• Timing groups are represented by the structure:
• Nu is a nucleophilic group attached to a position on CAR from which it will be displaced upon reaction of CAR with oxidized developing agent;
• E is an electrophilic group attached to an inhibitor moiety as described and is displaceable therefrom by Nu after Nu is displaced from CAR;
• LINK is a linking group for spatially relating Nu and E, upon displacement of Nu from CAR, to undergo an intramolecular nucleophilic displacement reaction with the formation of a 3- to 7-membered ring and thereby release the PUG moiety.
• a nucleophilic group (Nu) is defined herein as a group of atoms one of which is electron rich. Such an atom is referred to as a nucleophilic center.
• An electrophilic group (E) is defined herein as a group of atoms, one of which is electron deficient. Such an atom is referred to as an electrophilic center.
• the timing group can contain a nucleophilic group and an electrophilic group, which groups are spatially related with respect to one another by a linking group so that, upon release from CAR, the nucleophilic center and the electrophilic center will react to effect displacement of the PUG moiety from the timing group.
• the nucleophilic center should be prevented from reacting with the electrophilic center until release from the CAR moiety, and the electrophilic center should be resistant to external attack, such as hydrolysis.
• Premature reaction can be prevented by attaching the CAR moiety to the timing group at the nucleophilic center or an atom in conjunction with a nucleophilic center, so that cleavage of the timing group and the PUG moiety from CAR unblocks the nucleophilic center and permits it to react with the electrophilic center, or by positioning the nucleophilic group and the electrophilic group so that they are prevented from coming into reactive proximity until release.
• the timing group can contain additional substituents, such as additional photographically useful groups (PUGs) , or precursors thereof, which may remain attached to the timing group or be released.
• PUGs photographically useful groups
• the groups should be spatially related after cleavage from CAR so that they can react with one another.
• the nucleophilic group and the electrophilic group are spatially related within the timing group so that the intramolecular nucleophilic displacement reaction involves the formation of a 3- to 7-membered ring, most preferably a 5- or 6-membered ring.
• thermodynamics should be such and the groups be so selected that an overall free energy decrease results upon ring closure, forming the bond between the nucleophilic group and the electrophilic group, and breaking the bond between the electrophilic group and the PUG.
• nucleophilic group, linking group, and electrophilic group will yield a thermodynamic relationship favorable to breaking of the bond between the electrophilic group and the PUG moiety.
• Representative Nu groups contain electron rich oxygen, sulfur and nitrogen atoms.
• Representative E groups contain electron deficient carbonyl, thiocarbonyl, phosphonyl and thiophosphonyl moieties. Other useful Nu and E groups will be apparent to those skilled in the art.
• the linking group can be an acyclic group such as alkylene, for example, methylene, ethylene or propylene, or a cyclic group such as an aromatic group, such as phenylene or naphthylene, or a heterocyclic group, such as furan, thophene, pyridine, quinoline or benzoxazine.
• LINK is alkylene or arylene.
• the groups Nu and E are attached to LINK to provide, upon release of Nu from CAR, a favorable spatial relationship for nucleophilic attack of the nucleophilic center in Nu on the electrophilic center in E.
• Nu and E can be attached to the same or adjacent rings.
• Aromatic groups in which Nu and E are attached to adjacent ring positions are particularly preferred LINK groups.
• TIME can be unsubstituted or substituted.
• the substituents can be those which will modify the rate of reaction, diffusion, or displacement, such as halogen, including fluoro, chloro, bromo, or iodo, nitro, alkyl of 1 to 20 carbon atoms, acyl, such as carboxy, carboxyalkyl, alkoxycarbonyl, alkoxycarbonamido, sulfoalkyl, alkanesulfonamido, and alkylsulfonyl, solubilizing groups, ballast groups and the like, or they can be substituents which are separately useful in the photographic element, such as a stabilizer, an antifoggant, a dye (such as a filter dye or a solubilized masking dye) and the like.
• solubilizing groups will increase the rate of diffusion
• ballast groups will decrease the rate of diffusion
• electron withdrawing groups will decrease the rate of displacement of the PUG.
• electron transfer down a conjugated chain is understood to refer to transfer of an electron along a chain of atoms in which alternate single bonds and double bonds occur.
• a conjugated chain is understood to have the same meaning as commonly used in organic chemistry. This further includes TIME groups capable of undergoing fragmentation reactions where the number of double bonds is zero. Electron transfer down a conjugated chain is described in, for example, U.S. Patent No. 4,409,323.
• TIME moieties can have a finite half-life or an extremely short half-life. The half-life is controlled by the specific structure of the TIME moiety, and may be chosen so as to best optimize the photographic function intended. TIME moiety half-lives of from less than 0.001 second to over 10 minutes are known in the art. TIME moieties having a half-life of over 0.1 second are often preferred for use in PUG-releasing compounds that yield development inhibitor moieties, although use of TIME moieties with shorter half-lives to produce development inhibitor moieties is known in the art. The TIME moiety may either spontaneously liberate a PUG after being released from CAR, or may liberate PUG only after a further reaction with another species present in a process solution, or may liberate PUG during contact of the photographic element with a process solution.
• Couplers which form cyan dyes upon reaction with oxidized color developing agents are described in such representative patents and publications as: U.S. Patent Nos. 2,772,162; 2,895,826; 3,002,836; 3,034,892; 2,474,293; 2,423,730; 2,367,531; 3,041,236; 4,333,999, "Farbkuppler-eine Literaturubersicht, " published in Agfa Mitannonen, Band III, pp. 156-175 (1961), and Section VII D of Research Disclosure, Item 308119, December 1989.
• couplers are phenols and naphthols.
• Couplers which form magenta dyes upon reaction with oxidized color developing agent are described in such representative patents and publications as: U.S. Patent Nos. 2,600,788; 2,369,489; 2,343,703; 2,311,082; 3,152,896; 3,519,429; 3,062,653; 2,908,573, "Farbkuppler- niethacil- effet Literaturubersicht,” published in Agfa Mitannonen, Band III, pp. 126-156 (1961), and Section VII D of Research Disclosure, Item 308119, December 1989.
• couplers are pyrazolones or pyrazolotriazoles.
• Couplers which form yellow dyes upon reaction with oxidized and color developing agent are described in such representative patents and publications as: U.S. Patent Nos. 2,875,057; 2,407,210; 3,265,506; 2,298,443; 3,048,194; 3,447,928, "Farbkuppler-eine
• couplers are acylacetamides, such as benzoylac ⁇ tamide ⁇ and pivaloylacetamides.
• Couplers which form colorless products upon reaction with oxidized color developing agent are described in such representative patents as: U.K. Patent No. 861,138; U.S. Patent Nos. 3,632,345; 3,928,041; 3,958,993 and 3,961,959.
• couplers are cyclic carbonyl-containing compounds which react with oxidized color developing agents but do not form dyes.
• PUG groups that are useful in the present invention include, for example:
• Useful development inhibitors are iodide and heterocyclic compounds such as mercaptotetrazoles, selenotetrazoles, mercaptobenzothiazoles, selenobenzothiazoles, mercaptobenzoxazoles, selenobenzoxazole ⁇ , mercaptobenzimidazoles, selenobenzimidazoles, oxadiazoles, benzotriazoles, benzodiazoles, oxazoles, thiazoles, diazoles, triazoles, thiadiazoles, oxathiazoles, thiatriazoles, tetrazoles, benzimidazoles, indazoles, isoindazoles, mercaptooxazoles, mercaptothiadiazoles, mercaptothiazoles, mercaptotriazoles, mercaptooxadia
• G is S, Se, or Te, S being preferred; and wherein R 2a , R 2d , R 2h , R 2i , R 2 , R2 R 2q ⁇ a R 2r are individually hydrogen, substituted or unsubstituted alkyl, straight chained or branched, saturated or unsaturated, of 1 to 8 carbon atoms such as methyl, ethyl, propyl, butyl, 1-ethylpentyl, 2-ethoxyethyl, t-butyl or i-propyl; alkoxy or alkylthio, such as ethoxy, ethoxy, propoxy, butoxy, octyloxy, methylthio, ethylthio, propylthio, butylthio, or octylthiol; alkyl esters such as CO2CH3, CO2C2H5, CO2C3H7, CO2C4H9, CH2CO2CH3,
• R 2s is substituted or unsubstituted aryl, or a substituted or unsubstituted heterocyclic group; substituted or unsubstituted benzyl, such as methoxy-, chloro-, nitro-, hydroxy-, carboalkoxy-, carboaryloxy-, keto-, sulfonyl-, sulfenyl-, sulfinyl-, carbonamido-, sulfonamido-, carbamoyl-, or sulf moyl-substituted benzyl; substituted or unsubstituted aryl, such as phenyl, naphthyl, or chloro-, methoxy-, hydroxy-, nitro-, hydroxy-, carboalkoxy-, carboaryloxy-, keto-, sulfonyl-, sulfenyl-, sulfinyl
• R 2q and ⁇ a ⁇ so be a substituted or unsubstituted heterocyclic group selected from groups such as pyridine, pyrrole, furan, thiophene, pyrazole, thiazole, imidazole, 1,2,4-triazole, oxazole, thiadiazole, indole, benzthiophene, benzimidazole, benzoxazole and the like wherein the substitutents are as selected from those mentioned previously.
• R 2b, R 2c, R 2e # R 2f # an d R 2g are as described for R 2a # R 2d, R 2h # R 2i # R 2j, R 2k f R 2q R 2r. or# are individually one or more halogens such as chloro, fluoro or bromo and p is 0, 1, 2, 3 or 4.
• PUGs which are dves. or form dves iroon release Suitable dyes and dye precursors include azo, azomethine, azophenol, azonaphthol, azoaniline, azopyrazolone, indoaniline, indophenol, anthraquinone, triarylmethane, alizarin, nitro, quinoline, indigoid and phthalocyanine dyes or precursors of such dyes such as leuco dyes, tetrazolium salts or shifted dyes. These dyes can be metal complexed or metal complexable. Representative patents describing such dyes are U.S.
• Preferred dyes and dye precursors are azo, azomethine, azophenol, azonaphthol, azoaniline, and indoaniline dyes and dye precursors. Structures of typical dye ⁇ and dye precursors are:
• Suitable azo, azamethine and methine dyes are represented by the formulae in U.S. Patent No. 4,840884, col. 8, lines 1-70.
• Dyes can be chosen from those described, for example, in J. Fabian and H. Hartmann, Light J ⁇ _b ⁇ orptlon of Organic Colorants, published by Springer-Verlag Co., but are not limited thereto.
• Typical dyes are azo dyes having a radical represented by the following formula:
• X is a hetero atom such as an oxygen atom, a nitrogen atom and a sulfur atom
• Y is an atomic group containing at least one unsaturated bond having a conjugated relation with the azo group, and linked to X through an atom con ⁇ tituting the un ⁇ aturated bond
• the number of carbon atoms contained in Y and Z is 10 or more.
• Y and Z are each preferably an aromatic group or an unsaturated heterocyclic group.
• a ⁇ the un ⁇ aturated heterocyclic group, a 4- to 7-membered heterocyclic group containing at least one hetero atom selected from a nitrogen atom, a sulfur atom and an oxygen atom is preferred, and it may be part of a benzene-condensed ring system.
• the heterocyclic group means groups having a ring structure such as pyrrole, thiophene, furan, imidazole, 1,2,4-triazole, oxazole, thiadiazole, pyridine, indole, benzthiophene, benzimidazole, or benzoxazole.
• Y may be substituted with other groups as well as X and the azo groups.
• a carbamoyl group, an amino group, a ureido group, a sulfamoyl group, a carbamoyl ⁇ ulfonyl group and a hydrazino group are included.
• the ⁇ e group ⁇ may be further ⁇ ub ⁇ tituted with a group such as those disclo ⁇ ed above repeatedly, for example once or twice.
• substitution i ⁇ carried out repeatedly the uppermost number of carbon atoms of the thus obtained sub ⁇ tituent i ⁇ preferably 32.
• Y and Z contain an aryl moiety as a sub ⁇ tituent
• the number of carbon atoms of the moiety is generally from 6 to 10, and preferably it is a substituted or unsubstituted phenyl group.
• groups in the formulas shown hereinabove and hereinafter are defined as follows:
• An acyl group, a carbamoyl group, an amino group, a ureido group, a sulfamoyl group, a carbamoylsulfonyl group, an urethane group, a sulfonamido group, a hydrazino group, and the like represents unsubstituted groups thereof and sub ⁇ tituted group ⁇ thereof which are ⁇ ub ⁇ tituted with an aliphatic hydrocarbon group, an alicyclic hydrocarbon group or an aryl group to form mono-, di-, or tri- ⁇ ubstituted groups; an acylamino group, a sulfonyl group, a sulfonamido group, an acyloxy group and the like each is aliphatic alicyclic, and aromatic group.
• Typical examples of this group represented by formula for azo dyes shown above are contained in, for example, U.S. Patent Nos. 4,424,156 and 4,
• Coupler ⁇ released can be nondiffusible color-forming couplers, non-color forming couplers or diffu ⁇ ible competing coupler ⁇ .
• Representative patent ⁇ and publication ⁇ describing competing couplers are: " On the Chemistry of White Couplers, " by W. Puschel, Agfa-Gevaert AG Mit Minoren and der For ⁇ chung ⁇ -Laboratorium der Agfa-Gevaert AG, Springer Verlag, 1954, pp. 352-367; U.S. Patent No ⁇ . 2,998,314; 2,808,329; 2,689,793; 2,742,832; German Patent No. 1,168,769 and British Patent No.907,274. Structures of useful competing coupler ⁇ are:
• R 4a is hydrogen or alkylcarbonyl, such as acetyl
• R 4 b and R 4c are individually hydrogen or a solubilizing group, such as sulfo, aminosulfonyl, and carboxy
• R ⁇ d is as defined above and R ⁇ e is halogen, aryloxy, arylthio, or a development inhibitor, such as a mercaptotetrazole, ⁇ uch as phenylmercaptotetrazole or ethylmercaptotetrazole.
• Developing agents released can be color developing agents, black-and-white developing agents or cros ⁇ -oxidizing developing agent ⁇ . They include aminophenol ⁇ , phenylenediamines, hydroquinones and pyrazolidones. Representative patents are: U.S. Patent Nos. 2,193,015; 2,108,243; 2,592,364; 3,656,950; 3,658,525; 2,751,297; 2,289,367; 2,772,282; 2,743,279; 2,753,256 and 2,304,953.
• Structures of suitable developing agents are:
• R ⁇ a is hydrogen or alkyl of 1 to 4 carbon atoms and R ⁇ k is hydrogen or one or more halogen such a ⁇ chloro or bromo; or alkyl of 1 to 4 carbon atoms ⁇ uch a ⁇ methyl, ethyl or butyl group ⁇ .
• R 5c is hydrogen or alkyl of 1 to 4 carbon atoms and R 5d , R 5e , R 5f , R 5 9, and R 5n are individually hydrogen, alkyl of 1 to 4 carbon atoms such as methyl or ethyl; hydroxyalkyl of 1 to 4 carbon atoms such as hydr ⁇ xymethyl or hydroxyethyl or sulfoalkyl containing 1 to 4 carbon atoms.
• R 6a is alkyl or aryl of 6 to 20 carbon atoms
• R 7a is hydrogen, alkyl, such as methyl, ethyl, and butyl, alkoxy, such as ethoxy and butoxy, or alkylthio, such as ethylthio and butylthio, for example containing 1 to 6 carbon atoms, and which may be unsubstituted or substituted;
• R 7D is hydrogen, substituted or unsubstituted alkyl, or substituted or unsub ⁇ tituted aryl, ⁇ uch a ⁇ phenyl;
• R 7c , R 7d , R 7e and R 7f are individually hydrogen, ⁇ ub ⁇ tituted or un ⁇ ub ⁇ tituted alkyl, or ⁇ ub ⁇ tituted or unsubstituted aryl, such as straight chained or branched alkyl containing 1 to 6 carbon atoms, for example methyl, ethyl and butyl;
• s is 1 to 6;
• R 7a and R 7D are solubilizing functions by the structure:
• R 7c , R 7d , R 7e , R 7f , and ⁇ are a ⁇ defined above.
• PUGs which are electron transfer a ⁇ ents fBTAs, ETA ⁇ u ⁇ eful in the pre ⁇ ent invention are l-aryl-3-pyrazolidinone derivative ⁇ which, once released, become active electron transfer agent ⁇ capable of accelerating development under processing conditions used to obtain the de ⁇ ired dye image.
• the electron tran ⁇ fer agent pyrazolidinone moietie ⁇ which have been found to be useful in providing development acceleration function are derived from compounds generally of the type described in U S Patent Nos. 4,209,580;, 4,463,081; 4,471,045; and 4,481,287 and in published Japanese patent application No. 62-123,172.
• Also useful are the combinations disclosed in U.S. Patent No. 4,859,578.
• these compounds Preferably these compounds have one or more alkyl group ⁇ in the 4- or 5-po ⁇ ition ⁇ of the pyrazolidinone ring.
• Electron tran ⁇ fer agent ⁇ suitable for use in this invention are represented by the following two formula ⁇ :
• R 8b and R*- c each independently represents hydrogen, substituted or unsub ⁇ tituted alkyl having from 1 to about 8 carbon atom ⁇ (such as hydroxyalkyl) , carbamoyl, or substituted or unsub ⁇ tituted aryl having from 6 to about 10 carbon atoms;
• R 8 ⁇ and R 8e each independently represents hydrogen, substituted or unsubstituted alkyl having from 1 to about 8 carbon atoms or substituted or unsub ⁇ tituted aryl having from 6 to about 10 carbon atoms;
• R ⁇ f which may be present in the ortho, meta or para positions of the benzene ring, represents halogen, substituted or unsubstituted alkyl hving from 1 to about 8 carbon atoms, or substituted or unsubstituted alkoxy having from 1 to about 8 carbon atoms, or sulfonamido, and when m is greater than 1, the R ⁇ f substituents can be the same or different or can
• R 8b and R 8c group ⁇ are alkyl, it i ⁇ preferred that they compri ⁇ e. from 1 to 3 carbon atom ⁇ .
• R 8D and R 8c represent aryl, they are preferably phenyl.
• 8d and R 8e are preferably hydrogen.
• R ⁇ represents sulfonamido, it may be, for example, methanesulfonamido, ethane ⁇ ulfonamido or toluene ⁇ ulfonamido.
• DIRRs useful in the present invention include hydroquinone, catechol, pyrogallol,
• Couplers containing other suitable redox relea ⁇ er ⁇ can be found in for example, U.S. Patent No. 4,985,336;. col ⁇ . 17 to 62.
• Z represents an atomic group necessary to form a 5-, 6-, or 7-membered nitrogen-containing unsaturated heterocyclic ring containing 2 to 6 carbon atoms together with the nitrogen atom; DI represents a development inhibitor group; and R represents a substituent; and DI is connected to a carbon atom of the heterocyclic ring represented by Z through a hetero atom included therein, and the sulfonamido group is connected to a carbon atom of the heterocyclic ring represented by Z, provided that the nitrogen atom through which the heterocyclic group i ⁇ connected to the carrier moiety and the nitrogen atom in the sulfonamido group are positioned so as to satisfy the Kendall-Pelz rule as described, for example, in The Theory Of The Photographic Process, 4th edition, pp. 298-325.
• the group represented by the above formula is a group capable of being oxidized by the oxidation product of a developing agent. More specifically, the sulfonamido group thereon is oxidized to a sulfonylimino group from which a development inhibitor is cleaved.
• Specific examples of the just described development inhibiting redox releasers are as follows:
• the PUG-relea ⁇ ing compound is a development inhibitor-releasing (DIR) compound.
• DIR development inhibitor-releasing
• These DIR compounds may be incorporated in the same layer as the emulsions of this invention, in reactive association with this layer or in a different layer of the photographic material, all as known in the art.
• the ⁇ e DIR compound ⁇ may be among those clas ⁇ ified as "diffusable, " meaning that they enable relea ⁇ e of a highly tran ⁇ portable inhibitor moiety, or they may be cla ⁇ ified a ⁇ "non-diffusible", meaning that they enable release of a less transportable inhibitor moiety.
• the DIR compounds may comprise a timing Or linking group as known in the art.
• the inhibitor moiety of the DIR compound may be unchanged as the result of exposure to photographic processing solution. However, the inhibitor moiety may change in structure and effect in the manner disclo ⁇ ed in U.K. Patent No. 2,099,167; European Patent Application 167,168; Japane ⁇ e Kokai 205150/83; or U.S. Patent No. 4,782,012 as the result of photographic processing.
• the DIR compounds When the DIR compounds are dye-forming coupler ⁇ , they may be incorporated in reactive association with complementary color sen ⁇ itized ⁇ ilver halide emulsions, as for example a cyan dye-forming DIR coupler with a red sen ⁇ itized emul ⁇ ion or in a mixed mode, for example, a yellow dye-forming DIR coupler with a green sensitized emulsion, all known in the art.
• the DIR compound ⁇ may al ⁇ o be incorporated in reactive a ⁇ ociation with bleach accelerator-releasing couplers, a ⁇ di ⁇ clo ⁇ ed in U.S. Patent Nos. 4,912,024 and 5,135,839, and with the bleach accelerator-releasing compounds disclo ⁇ ed in U.S. Patent No ⁇ . 4,865,956 and 4,923,784, all incorporated herein by reference.
• the dye image-forming compounds and PUG-releasing compounds can be incorporated in photographic elements of the present invention by means and proce ⁇ e ⁇ known in the photographic art.
• a photographic element in which the dye image-forming and PUG-releasing compounds are incorporated can be a monocolor element comprising a support and a single silver halide emulsion layer, or it can be a multicolor, multilayer element comprising a support and multiple silver halide emulsion layers.
• the above described compounds can be incorporated in at least one of the ⁇ ilver halide emulsion layers and/or in at lea ⁇ t one other layer, such as an adjacent layer, where they are in reactive association with the silver halide emulsion layer and are thereby able to react with the oxidized developing agent produced by development of silver halide in the emulsion layer.
• the silver halide emulsion layer ⁇ and other layers of the photographic element can contain addenda conventionally contained in such layers.
• a typical multicolor, multilayer photographic element can comprise a support having thereon a red-sensitized silver halide emulsion unit having associated therewith a cyan dye image-forming compound, a green-sensitized silver halide emulsion unit having associated therewith a magenta dye image-forming compound, and a blue-sensitized silver halide emulsion unit having as ⁇ ociated therewith a yellow dye image- forming compound.
• Each ⁇ ilver halide emulsion unit can be composed of one or more layers, and the various units and layers can be arranged in different locations with respect to one another, as known in the prior art and as illustrated by layer order formats hereinafter described.
• a layer or unit affected by PUG can be controlled by incorporating in appropriate locationcn ⁇ in the element a layer that confine ⁇ the action of PUG to the de ⁇ ired layer or unit.
• one of the layer ⁇ of the photographic element can be, for example, a scavenger layer, a mordant layer, or a barrier layer. Examples of such layers are described in, for example, U.S. Patent No ⁇ . 4,055,429; 4,317,892; 4,504,569; 4,865,946; and 5,006,451.
• the element can also contain additional layers such as antihalation layers, filter layers and the like. " The element typically will have a total thickness, excluding the support, of from 5 to 30 m.
• Thinner formulations of 5 to about 25 m are generally preferred ⁇ ince these are known to provide improved contact with the proces ⁇ solutions. For the same reason, more swellable film structures are likewise preferred. Further, this invention may be particularly useful with a magnetic recording layer such as those described in Research Disclosure, Item 34390, November 1992, p. 869.
• the element ⁇ of thi ⁇ invention can include additional dye image-forming compound ⁇ , as described in Section ⁇ VII A-E and H, and additional PUG-relea ⁇ ing compound ⁇ , a ⁇ described in Sections VII F and G of Research Disclosure, December 1989, Item 308119, and the publications cited therein.
• the elements of this invention can contain brighteners (Section V) , antifoggants and stabilizer ⁇ (Section VI) , anti ⁇ tain agent ⁇ and image dye stabilizers (Section VII I and J) , light absorbing and scattering materials (Section VIII) , hardeners (Section X) , coating aids (Section XI) , plasticizers and lubricants (Section XII), antistatic agents (Section XIII), matting agents (SectionXVI) , and development modifiers (Section XXI) , all in .Re-search Disclosure, December 1989, Item 308119.
• the elements of the invention can be coated on a variety of support ⁇ , a ⁇ described in Section XVII of Research Disclosure, December 1989, Item 308119, and references cited therein.
• processing to form a visible dye image includes the step of contacting the element with a color developing agent to reduce developable silver halide and oxidize the color developing agent. Oxidized color developing agent in turn reacts with the coupler to yield a dye.
• Preferred color developing agents are p-phenylenediamines.
• 4-amino-3- methyl-N,N-diethylaniline hydrochloride 4-amino-3- methyl-N-ethyl-N— (methane ⁇ ulfonamido)ethylaniline sulfate hydrate, 4-amino-3-methyl-N-ethyl-N— hydroxyethylaniline sulfate, 4-amino-3— (methane ⁇ ulfonamido)ethyl-N,N-diethylaniline hydrochloride, and 4-amino-N-ethyl-N-(2-methoxyethyl)m- toluidine di-p-toluene ⁇ ulfonic acid.
• the proces ⁇ ing step described above provides a negative image.
• the de ⁇ cribed element ⁇ are preferably proce ⁇ ed in the known Kodak Flexicolor C-41 color proce ⁇ s as described in, for example, the British Journal of Photography Annual of 1988, page ⁇ 196-198.
• the color development step can be preceded by development with a non-chromogenic developing agent to develop exposed silver halide but not form dye, and then uniform fogging of the element to render unexposed silver halide developable.
• the Kodak E- 6 Process is a typical reversal process.
• Table 1 contains the formulas of typical dye image-forming coupler compound ⁇ .
• Table 2 contain ⁇ the formulas of typical PUG-releasing compounds that release development inhibitor groups or precursors thereof.
• Table 3 are shown the formulas of representative examples of other kinds of PUG-releasing compounds.
• Table 4 provides the formulas of miscellaneous exemplary photographic compounds that can be used in elements of the invention.
• the color photographic elements of this invention can contain any of the optional additional layers and components known to be useful in color photographic elements in general, such as, for example, subbing layers, overcoat layers, surfactants and plasticizers, some of which are discussed in detail hereinbefore. They can be coated onto appropriate supports using any suitable technique, including, for example, those described in Research Disclosure, December 1989, Item 308117, Section XV Coating and Drying Procedures, published by Industrial Opportunities Ltd., Homewell Havant, Hampshire, P09 1EF, U.K., the disclosure of which is incorporated herein by reference.
• the photographic elements containing radiation sensitive ⁇ 100 ⁇ tabular grain emulsion layers 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.
• 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.
• This Preparation demonstrates the preparation of an ultrathin tabular grain silver iodochloride emulsion satisfying the requirements for use in a color photographic element of this invention.
• a 2030 mL solution containing 1.75% by weight low methionine gelatin (gelatin that has been treated with an oxidizing agent to reduce its methionine content to less than 30 micromoles per gram), 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. While this solution was vigorously stirred, 30 mL of 1.0 M silver nitrate solution and 30 mL of a 0.99 M sodium chloride and 0.01 M potassium iodide solution were added simultaneously at a rate of 30 mL/min each. This achieved grain nucleation to form crystals with an initial iodide concentration of 2 mole percent, based on total silver.
• 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 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 23 and an average tabularity (ECD/t 2 ) 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 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 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.
• a color photographic element of the present invention can comprise a single radiation-sensitive emulsion layer on a support.
• the element can contain a radiation-sensitive layer coated on each side of a support, a so-called duplitized format.
• Particularly useful embodiments are multicolor multilayer elements that contain a red light-sensitized, a green light-sensitized, and a blue light-sensitized unit, each unit containing at least one dye image-forming compound in reactive association with a radiation- sensitive silver halide emulsion.
• the color photographic element of the invention can be used in conjunction with an applied magnetic layer as described in Research Disclosure, November 1992, Item 34390 published by Kenneth Mason Publications, Ltd., Dudley Annex, 12a North Street, Emsworth, Hampshire P010 7DQ, ENGLAND.
• antihalation layers which are applied in immediate proximity to, and on either side of, the support.
• protective overcoat layers which can contain gelatin, dyes, ultraviolet light absorbers, polymeric beads, and the like, and are applied above the uppermost dye image-forming unit.
• red-sensitized, cyan dye image-forming silver halide emulsion unit is situated nearest the support; next in order is the green-sensitized, magenta dye image- forming unit, followed by the uppermost blue-sensitized, yellow dye image-forming unit.
• the image-forming units are typically separated from each other by interlayers, as shown.
• Each of the image-forming units can contain a single radiation-sensitive silver halide emulsion layer.
• each unit can independently contain two or three layers of differing sensitivity, referred to, respectively, as slow, fast or slow, medium, fast in order of increasing radiation sensitivity.
• a tabular silver chloride emulsion containing grains bounded by ⁇ 100 ⁇ major faces and in reactive association with a dye image- forming compound and a PUG-releasing compound can be contained in the blue-sensitized silver halide emulsion unit only, or it can be contained in each of the silver halide emulsion units.
• the tabular silver chloride emulsion can be in the layer of lowest sensitivity (the slow layer) , or it can be in other or all the emulsion layers in the unit.
• blue-sensitized, yellow dye image-forming silver halide unit is situated nearest the support, followed next by the red-sensitized, cyan dye image- forming unit, and uppermost the green-sensitized, magenta dye image-forming unit.
• the individual units are typically separated from one another by interlayers.
• each of the image-forming units can comprise a single radi ' ation- sensitive layer, or each can independently include two (slow, fast) or three (slow, medium, fast) silver halide emulsion layers of differing sensitivity.
• a tabular ⁇ ilver chloride emulsion containing grains bounded by ⁇ 100 ⁇ major faces can be located in the blue-sensitized silver halide emulsion unit only, or it can be in each of the units. Where a unit comprises more than one radiation-sensitive layer, the tabular silver chloride emulsion can be in the layer of lowest sensitivity, or in other or all of the layers in the unit.
• a slower red-sensitized silver halide emulsion layer of the cyan dye image-forming unit is situated nearest the support, followed in order by a slower green- sensitized silver halide emulsion layer of the magenta dye image-forming unit, a fast red-sensitized silver halide emulsion layer of the cyan dye image-forming unit, and a fast green-sensitized silver halide emulsion layer of the magenta dye image-forming unit.
• Uppermost is the blue-sensitized yellow dye image-forming silver halide emulsion unit, which can comprise one, two, or three emulsion layers.
• image-forming units are typically separated from each other by " interlayers.
• Elements of the present invention having the layer order shown in Structure III can contain tabular silver chloride emulsions having grains bounded by ⁇ 100 ⁇ major faces in the slow emulsion layer of the yellow dye image-forming unit, as well as in the faster emulsion layers of this unit.
• Tabular silver halide emulsions can also be employed in the layers of lowest sensitivity in the green- and/or red-sensitized emulsion units, as well as in all of the other radiation- sensitive layers of the element.
• the positions of the slower and the fast silver halide emulsion layers are transposed in both the red-sensitized and in the green-sensitized emulsion units; i.e., the positions of the slower and the fast green-sensitized emulsion layers are reversed from their positions in Structure IVa, as are the positions of the red-sensitized emulsion layers.
• the emulsions with tabular ⁇ 100 ⁇ -faced silver chloride grains can be situated in the overlying slower layers in the green- and red-sensitized silver halide emulsion units, or they can be utilized in all of the radiation-sensitive layers of the element.
• Control silver halide emulsions and tabular silver chloride emulsions bounded by ⁇ 100 ⁇ major -faces in accordance with the present invention were prepared and sensitized as described below.
• the emulsions and a summary of their characteristics are listed in Table 5.
• the cubic silver chloride control emulsions whose grains have predominantly ⁇ 100 ⁇ faces, were prepared according to procedures described in U.S. Patent No. 4,952,491 and in Section I of J?esearci Disclosure, Item 308119, December 1989. These emulsions were sensitized to green, blue, or red light by methods known in the art.
• the cubic silver iodobromide emulsions were prepared by the procedures contained in Section I of Research Disclosure, Item 308119, December 1989. Sensitization was carried out by methods known in the art.
• Tabular silver iodobromide emulsions were prepared and sensitized by procedures recorded in U.S. Patent No.
• Solution 1 was charged into a reaction vessel equipped with a stirrer.
• Solution 2 was added to the reaction vessel. While the mixture, which was at a pH of 6.0 and a temperature of 40C, was vigorously stirred, Solution 3 and Solution 4 were added at 80 mL/min. for 0.5 minute. The VAg was adjusted to 175 mV, and the mixture was held for ten minutes. Following this hold, Solution 3 and Solution 4 were added simultaneously at 24 mL/in. for 40 minutes; then the flow was linearly accelerated from 24 mL/min. to 48 mL/min. over 130 minutes, while the VAg was maintained at 175 mV. Solution 5 was added and stirred for 5 minutes.
• the pH was then adjusted to 3.8, and the gel was allowed to settle while the temperature was lowered to 15C.
• the liquid layer was decanted, and the depleted volume was restored with distilled water.
• the pH was adjusted to 4.5, and the mixture held at 40C for 5 minutes before the pH was adjusted to 3.8 and the settling and decanting steps were repeated.
• Solution 6 was added, and the pH and VAg were adjusted to 5.6 and 130 mV, respectively.
• the resulting emulsion contained tabular silver chloride grains having predominantly ⁇ 100 ⁇ faces, an average equivalent circular diameter (ECD) of 1.2 m, and an average thickness of 0.12 m.
• ECD average equivalent circular diameter
• the emulsion thus produced was sensitized to green light by treating it with 1 percent NaBr, holding for 5 minutes, adding spectral sensitizing dyes SS-22 and
• Solution 4 and Solution 6 were added at 180 mL/min. for 30 seconds. The reaction mixture was then held for 10 minutes. Following this hold, Solution 3 and Solution 5 were added simultaneously at 24 mL/min. for 40 minutes, while the pCl was maintained at 1.91. The rate was then accelerated to 48 mL/min. over 130 minutes. The mixture was cooled to 40C; Solution 7 was added, and the mixture was stirred for 5 minutes. The pH was then adjusted to 3.8, and the gel was allowed to settle while the temperature was lowered to 15C. The liquid layer was decanted, and the depleted volume was restored with distilled water. The pH was adjusted to 4.5, and the mixture was held at 40C for 20 minutes before the pH was adjusted to 3.8 and the settling and decanting steps were repeated. Solution 8 was added, and the pH and pCl were adjusted to 5.6 and 1.6, respectively.
• the resulting emulsion contained tabular silver chloride grains having predominantly ⁇ 100 ⁇ faces, and average equivalent circular diameter (ECD) of 1.4 m, and an average thickness of 0.14 m.
• ECD average equivalent circular diameter
• the emulsion thus produced was sensitized to green light by treating it with 1 percent NaBr, holding for 5 minutes, adding spectral sensitizing dyes SS-22 and SS-26 at a 3:1 ratio, holding for 10 minutes, adding Na2S2U35H2 ⁇ at 1.0 mg per mol and KAUCI4 at 1.3 mg per mol, and heating for 10 minutes at 60C to produce EM-5.
• red light sen ⁇ itized emul ⁇ ion EM-8 was obtained using spectral sensitizing dyes SS-25 and SS-23 at a 1:2 ratio
• blue light sensitized emulsion EM-11 was obtained using spectral sensitizing dye SS-1.
• the mixture was then held for 5 minutes; 7000 mL of distilled water was 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 u ⁇ ing 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 well-agitated continuous reactor with a total volume of 30 mL.
• 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 crystal ⁇ through Ostwald ripening.
• the total suspension volume of the growth reactor during this growth step was maintained constant at 13.5 L u ⁇ ing 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 wa ⁇ 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.
• This emulsion was ⁇ ensitized to red light by treating it with 1 percent NaBr, holding for 5 minutes, adding spectral sensitizing dye (SS-25 and SS-23 at 2:1 ratio), holding for 10 minutes, adding Na2S2 ⁇ 35H2 ⁇ at 1.0 mg per mol and KAUCI4 at 1.3 mg per mol, and heating for 10 minutes at 60C.
• spectral sensitizing dye SS-25 and SS-23 at 2:1 ratio
• Sample 101 was prepared by applying the following layers to a clear support in the order indicated. Quantities of components are expressed in grams per square meter.
• Layer 1 (antihalation layer) comprising gray silver and gelatin.
• Layer 2 (light sen ⁇ itive layer) compri ⁇ ing 0.32 g of EM-lc, 0.54 g of image dye forming coupler C-1 and 1.54 g gelatin.
• Layer 3 (protective layer) comprising 2.15 g of gelatin.
• the layers additionally comprised alpha-4- nonylphenyl-omega-hydroxy-poly(oxy- (2-hydroxy-1,3- propanediyl) ) and (para-t-octylphenyl)-di(oxy-1,2- ethanediyl)-sulfonate as surfactants.
• This film was hardened at coating with 2% by weight to total gelatin of bis-vinylsulfonylmethane.
• Sample 102 was prepared like sample 101 except that emulsion EM-lc was replaced by an equal quantity of emulsion EM-2c.
• Sample 103 was prepared like sample 101 except that emulsion EM-lc was replaced by an equal quantity of emulsion EM-3c.
• Sample 104 was prepared like sample 101 except that emulsion EM-lc was replaced by an equal quantity of emulsion EM-4.
• Sample 105 was prepared like sample 101 except that emulsion EM-lc was replaced by an equal quantity of emulsion EM-5.
• Sample 106 was prepared like sample 105 except that image dye forming coupler C-1 was replaced by 0.32 g of image dye forming coupler C-2.
• Sample 107 was prepared like sample 101 except that emulsion EM-lc was replaced by an equal quantity of emulsion EM-6c.
• Sample 108 was prepared like sample 101 except that emulsion EM-lc was replaced by an equal quantity of emulsion EM-7.
• Sample 109 was prepared like sample 101 except that emulsion EM-lc was replaced by an equal quantity of emul ⁇ ion EM-8.
• Sample 110 was prepared like sample 101 except that emulsion EM-lc was replaced by an equal quantity of emulsion EM-9c and image dye-forming coupler C-1 was replaced by 1.08 g of image dye-forming coupler C-3.
• Sample 111 was prepared like sample 110 except that emulsion EM-9c was replaced by an equal quantity of emulsion EM-10.
• Sample 112 was prepared like sample 110 except that emulsion EM-9c was replaced by an equal quantity of emulsion EM-11.
• Coupler C-1 is a cyan image dye-forming coupler
• C-2 is a magenta image dye-forming coupler
• C-3 is a yellow image dye-forming coupler.
• the couplers were provided as photographic coupler disper ⁇ ion ⁇ , as known in the art.
• Samples 101-112 were exposed to white light through a graduated density test object and proces ⁇ ed using the KODAK C-41 process.
• the process was modified in that the bleach solution comprised ferric propylenediamine-tetraacetate.
• the photographic sensitivity was measured as the exposure required to enable a Status M density of 0.15 above Dmin after processing.
• the Status M density at a Dmax value was also mea ⁇ ured.
• Table 6 lists for each ⁇ ample: the emulsion identity; surface area per grain; color sensitization; dye image-forming coupler; the experimentally observed relative sensitivity; the relative sensitivity expected as ⁇ uming that, for a spectrally sensitized emulsion, the sensitivity is a linear function of grain surface area; and the Status M dye density formed at Dmax per gram of coupler coated per square meter per gram of silver per square meter in each sample, i.e., the normalized dye-density yield (DDY) .
• control samples 101, 102 and 103 illustrate the difficulty of achieving either high photographic sensitivity or high values of dye- density yield with cubic shaped ⁇ 100 ⁇ AgCl grains.
• photographic sen ⁇ itivity hardly increases at all while dye density yield falls dramatically.
• the photographic sensitivity would be expected to increase directly as a function of surface area per grain for spectrally sen ⁇ itized emulsions, this expectation was not fulfilled for the control samples.
• samples 104 and 105 of the invention showed photographic sen ⁇ itivity greatly exceeding that expected based on relative grain surface area.
• the dye density yield achieved in these samples exceeded that available from even less photographically sen ⁇ itive control samples.
• sample 106 of the invention demonstrates that both the sensitivity and dye density yield can be further improved by choosing image dye-forming couplers that require a lower stoichiometric quantity of oxidized developer for dye formation (coupler C-2 is a 2-equivalent image coupler; coupler C-1 is a 4-equivalent image coupler) , or by choosing an image coupler that forms a high extinction image dye.
• the re ⁇ ult ⁇ from samples 107 through 109 and from samples 110 through 112 show that these beneficial effects were also obtained from samples of the invention that are sensitive to red and blue light, respectively.
• the photographic samples according to this invention provide not only greatly improved photographic sen ⁇ itivity compared to the control samples but also provide surpri ⁇ ingly high dye den ⁇ ity formation relative to the control ⁇ amples.
• the above-described sample ⁇ were exposed to white light through a graduated density test object and developed for 195 seconds using the color paper developer described in U.S. Patent No. 4,892,804. Results like those shown in Table 1 were obtained.
• Change ⁇ in contact time of a photographic material with a processing solution are typically employed by those skilled in the art to approximate the effects of changes in temperature or the concentration of components in the processing solution.
• a longer process time approximates the effect of increased component concentration or temperature, or both
• a shorter proces ⁇ time approximate ⁇ the effect of decreased component concentration or temperature, or both.
• Control samples 201 through 205 were prepared by applying the following layers to a clear support in the order indicated. Quantities of components are expre ⁇ ed in grams per square meter.
• Layer 1 (antihalation layer) comprising gray silver and gelatin.
• Layer 2 (light sensitive layer) comprising 0.54 g of EM-13c, 0.54 g of image dye forming coupler C-1, 1.54 g gelatin, and amounts of various DIR compounds as listed in Table 7, below.
• Layer 3 (protective layer) comprising 2.15 g of gelatin.
• the layers additionally comprised alpha-4- nonylphenyl-omega-hydroxy-poly(oxy-(2-hydroxy-l,3- propanediyl) ) and (para-t-octylphenyl)-di(oxy-1,2- ethanediyl)-sulfonate as surfactant ⁇ . These films were hardened at coating with 2% by weight to total gelatin of bis-vinylsulfonylmethane.
• Control samples 206 through 211 were prepared like samples 201 - 205, except that emulsion EM-i3c was replaced by an equal weight of emul ⁇ ion EM-14c.
• Control ⁇ amples 301 through 303 were prepared like sample ⁇ 201 - 205, except that emulsion EM-13c was replaced by an equal weight of emulsion EM-6c.
• Control samples 304 through 306 were prepared like samples 201 - 205, except that emulsion EM-13c was replaced by an equal weight of emulsion EM-9c.
• Control samples 307 through 311 were prepared like samples 201 - 205, except that emulsion EM-13c was replaced by an equal weight of emulsion EM-12c.
• Control samples 312 through 315 were prepared like samples 201 - 205, except that emulsion EM-13c was replaced by an equal weight of emulsion EM-3c.
• Samples 316 through 321 were prepared like samples 201 - 205, except that emulsion EM-13c was replaced by an equal weight of emul ⁇ ion EM-4.
• Samples 322 through 329 were prepared like samples 201 - 205, except that emulsion EM-13c was replaced by an equal weight of emulsion EM-4.
• Samples 201 through 329 were exposed to light through a graduated density test object and processed as color negative films according to the KODAK C-41 process.
• the proces ⁇ wa ⁇ modified in that the bleach solution comprised ferric propylenediamine-tetraacetate.
• the useful latitude of each sample was quantified by determining the exposure required to enable a Status M density 0.10 above Dmin and the exposure required to enable a Status M density 0.10 below Dmax for each sample. The larger the difference in exposure, the greater the useful latitude of the sample. Combinations of emulsion ⁇ and development inhibitor-relea ⁇ ing (DIR) compounds that enable a large increase in latitude can be especially useful.
• the photographic gamma of each sample was quantified as the rate of change of the Status M density obtained after processing as a function of log exposure, at exposure values towards the center of the samples' useful latitude. Combinations of emulsions and DIR compounds that enable a significant decrease in gamma can also be especially useful.
• Samples 201 through 211 contain either cubic or tabular shaped silver iodobromide emulsions similar to tho ⁇ e typically employed in combination with DIR compound ⁇ . The results illustrate the large increase in latitude and the large decrease in gamma enabled by these combinations.
• Samples 301 through 315 contain cubic shaped silver chloride emulsions known in the art.
• the results demonstrate that combinations of these cubic silver chloride emulsions with a variety of DIR compounds typically leads to, at best, a very modest increase in useful latitude and a modest reduction in gamma. In some cases latitude was truncated, while in others gamma was increased. This behavior can be related to gross sensitivity losses encountered with these combinations, or to changes in Dmin.
• Samples 317-321 and 323-329 illustrate the combination of tabular shaped ⁇ 100 ⁇ surface AgCl cry ⁇ tals and DIR compounds, in accordance with the present invention.
• Samples 901 through 969 were prepared generally as described for sample 101 of Example 2. All of these sample ⁇ were coated on a tran ⁇ parent support. Samples 970 through 972 were coated on a reflective support. All of these elements represent further illustrations of the practice of this invention.
• the identification and quantity of the silver halide emulsion and the identification and quantity of the image dye-forming and PUG-releasing coupler compounds employed in each sample are provided in Table 8 below.
• the samples were exposed to light through a graduated density test object and proces ⁇ ed u ⁇ ing the Kodak C-41 process.
• the process was modified in that the bleach solution comprised ferric propylenediamine-tetraacetate.
• the ⁇ tatu ⁇ M density in the red, green or blue band corresponding to the peak absorption wavelength exhibited by the sample was employed. Transmission density was measured for samples 901 through 969; reflection density was mea ⁇ ured for samples 970 through 972.
• Table 8 shows the identity and quantity of the emulsion and coupler compounds employed in each element.
• Samples 901 through 969 were exposed to white light through a graduated density test object and developed for 45 seconds in the color paper developer described in U.S. Patent No. 4,892,804, then bleached and fixed. Good dye density formation from the ⁇ e element ⁇ wa ⁇ again observed.
• Samples 401 through 412 were prepared by applying the following layers to a clear support in the order indicated. Quantities of components are expressed in grams per square meter.
• Layer 1 (antihalation layer) comprising gray silver and gelatin.
• Layer 2 (light sensitive layer) comprising 0.33 g of
• Layer 3 (protective layer) comprising 2.15 g of gelatin.
• the layers additionally comprised alpha-4- nonylphenyl-omega-hydroxy-poly(oxy- (2-hydroxy-1,3- propanediyl) ) and (para-t-octylphenyl)-di(oxy-1,2- ethanediyD-sulfonate as surfactant ⁇ .
• Samples 401 through 412 were exposed to ⁇ inu ⁇ oidal pattern ⁇ of white light to determine the
• Modulation Transfer Function (MTF) Percent Respon ⁇ e a ⁇ a function of spatial frequency in the film plane.
• the sample ⁇ were then processed using the KODAK C-41 process.
• the bleach used in the process was modified to comprise 1,3-propylenediamine-tetraacetic acid.
• the exposed and processed elements were evaluated to determine the MTF Percent Response as a function of spatial frequency in the film plane. Specific details of thi ⁇ expo ⁇ ure - evaluation cycle can be found at R. L. Lambert ⁇ and F. C. Ei ⁇ en, "A Sy ⁇ tem for the Automatic Evaluation of
• MTF Percent Response of the light sensitive layers of these samples was monitored at several spatial frequencies. Higher values for MTF Percent Respon ⁇ e indicate a sharper image. Additionally, the spatial frequency at which the MTF Percent Response dropped to 70%, which is a mea ⁇ ure of re ⁇ olving power, was determined. Higher spatial frequencies indicate a film with superior resolving power. The results of this test are also listed in Table 9. 188
• elements of the invention containing a variety of DIR compounds all exhibited enhanced sharpnes ⁇ and generally improved resolving power.
• the specific spatial frequencies enhanced and the degree of enhancement varies with the choice of dye image-forming and DIR coupler compounds. Combinations suitable for specific applications are readily ascertained by those ⁇ killed in the art.
• Samples 501 through 504 were prepared by applying the following layers to a clear support in the order indicated. Quantities of components are expressed in gram ⁇ per square meter.
• Layer 1 antihalation layer
• Layer 1 comprising gray silver and gelatin.
• Layer 2 (light sensitive layer) comprising 0.43 g of
• Layer 3 (protective layer) comprising 2.15 g of gelatin.
• the layers additionally compri ⁇ ed alpha-4- nonylphenyl-omega-hydroxy-poly(oxy-(2-hydroxy-l,3- propanediyl) ) and (para-t-octylphenyl)-di(oxy-1,2- ethanediyl)- ⁇ ulfonate as surfactant ⁇ .
• Samples 501 through 504 were exposed to white light through a graduated density test object, then proces ⁇ ed using the KODAK C-41 proces ⁇ .
• the bleach u ⁇ ed in the proce ⁇ s was modified to comprise 1,3- propylenediamine-tetraacetic acid.
• the relative photographic sensitivities of the samples were then evaluated by determining the exposure required to produce a density of 0.15 above Dmin at a normalized gamma of 1.0.

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