EP0111919A2 - Silberjodidteilchen enthaltende farbphotographische Elemente - Google Patents

Silberjodidteilchen enthaltende farbphotographische Elemente Download PDF

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EP0111919A2
EP0111919A2 EP83112771A EP83112771A EP0111919A2 EP 0111919 A2 EP0111919 A2 EP 0111919A2 EP 83112771 A EP83112771 A EP 83112771A EP 83112771 A EP83112771 A EP 83112771A EP 0111919 A2 EP0111919 A2 EP 0111919A2
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Prior art keywords
silver
emulsion
grains
tabular
blue
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French (fr)
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EP0111919B1 (de
EP0111919A3 (en
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Gary Lawrence House
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Eastman Kodak Co
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Eastman Kodak Co
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • 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

Definitions

  • the invention relates to silver halide photographic elements capable of producing multicolor images and to processes for their use.
  • the crystal structure of silver iodide has been studied by crystallographers, particularly by those interested in photography. As illustrated by Byerley and Hirsch, "Dispersions of Metastable High Temperature Cubic Silver Iodide", Journal of Photographic Science, Vol. 18, 1970, pp. 53-59, it is generally recognized that silver iodide is capable of existing in three different crystal forms.
  • the most commonly encountered form of silver iodide crystals is the hexagonal wurtzite type, designated B phase silver iodide.
  • Silver iodide is also stable at room temperature in its face centered cubic crystalline form, designated y phase silver iodide.
  • a third-form of crystalline silver iodide, stable only at temperatures above about 147°C, is the body centered cubic form, designated a phase silver iodide.
  • the B phase is the most stable form of silver iodide.
  • This object is accomplished with a multicolor photographic element having the above features and characterized in that at least 50 percent of the total projected area of the silver halide grains in at least one emulsion layer is provided by thin tabular silver iodide grains having a thickness of less than 0.3 pm and an average aspect ratio of greater than 8:1, aspect ratio being defined as the ratio of grain diameter to grain thickness and grain diameter being defined as the diameter of a circle having an area equal to the projected area of the silver halide grain.
  • the multicolor photographic elements of this invention exhibit high efficiencies in the absorption of blue light. They can display reduced color contamination of minus blue (i.e., red and/or green) records by blue light.
  • the multicolor photographic elements of this invention can eliminate yellow filter layers without exhibiting color contamination of the minus blue record.
  • the multicolor elements of this invention can exhibit improvements in image sharpness and in speed-grain relationships of the minus blue records.
  • This invention is directed to photographic elements capable of producing multicolor images and to processes for their use.
  • the multicolor photographic elements of this invention each incorporate at least one silver halide emulsion layer comprised of a dispersing medium and silver halide grains. At least 50 percent of the total projected area of the silver halide grains in the blue recording emulsion layer is provided by thin tabular grains having a thickness of less than 0.3 pm and an average aspect ratio of greater than 8:1.
  • This emulsion layer is preferably a blue recording emulsion layer and is for convenience described below with reference to this use, except as specifically noted.
  • the multicolor photographic elements additionally include at least one green recording silver halide emulsion layer and at least one red recording silver halide emulsion layer.
  • the multicolor photographic elements can also optionally include one or more additional blue recording emulsion layers. All of these additional emulsion layers can be chosen from among conventional multicolor photographic element emulsion layers.
  • at least one green recording emulsion layer and at least one red recording emulsion layer are also comprised of high aspect ratio tabular grain emulsions.
  • all of the emulsion layers can be comprised of high aspect ratio tabular grain emulsions.
  • Tabular silver iodide grains satisfying the same general requirements as those of the blue recording emulsion layer described above can be present in any or all of these additional emulsion layers, or high aspect ratio tabular grain silver halide emulsions of other halide compositions can be present in any or all of these additional emulsion layers.
  • the term "high aspect ratio" is herein defined as requiring that the silver halide grains having a thickness of less than 0.3 pm have an average aspect ratio of greater than 8:1 and account for at least 50 percent of the total projected area of the silver halide grains.
  • the preferred high aspect ratio tabular grain silver halide emulsions of the present invention are those wherein the silver halide grains having a thickness of less than 0.3 ⁇ m (optimally less than 0.2 pm) have an average aspect ratio of at least 12:1 and optimally at least 20:1.
  • the grain characteristics described above of the high aspect ratio tabular grain emulsions can be readily ascertained by procedures well known to those skilled in the art.
  • the term "aspect ratio” refers to the ratio of the diameter of the grain to its thickness.
  • the "diameter” of the grain is in turn defined as the diameter of a circle having an area equal to the projected area of the grain as viewed in a photomicrograph (or an electron micrograph) of an emulsion sample. From shadowed electron micrographs of emulsion samples it is possible to determine the thickness and diameter of each grain and to identify those tabular grains having a thickness of less than 0.3 pm.
  • the aspect ratio of each such tabular grain can be calculated, and the aspect ratios of all the tabular grains in the sample meeting the less than 0.3 pm thickness criterion can be averaged to obtain their average aspect ratio.
  • the average aspect ratio is the average of individual tabular grain aspect ratios. In practice it is usually simpler to obtain an average thickness and an average diameter of the tabular grains having a thickness of less than 0.3 pm and to calculate the average aspect ratio as the ratio of these two averages. Whether the averaged individual aspect ratios or the averages of thickness and diameter are used to determine the average aspect ratio, within the tolerances of grain measurements contemplated, the average aspect ratios obtained do not significantly differ.
  • the projected areas of the silver iodide grains meeting the thickness and diameter criteria can be summed, the projected areas of the remaining silver iodide grains in the photomicrograph can-be summed separately, and from the two sums the percentage of the total projected area of the silver iodide grains provided by the grains meeting the thickness and diameter critera can be calculated.
  • a reference tabular grain thickness of less than 0.3 pm was chosen to distinguish the uniquely thin tabular grains herein contemplated from thicker tabular grains which provide inferior photographic properties. At lower diameters it is not always possible to distinguish tabular and nontabular grains in micrographs.
  • the tabular grains for purposes of this disclosure are those which are less than 0.3 ⁇ m in thickness and appear tabular at 2,500 times magnification.
  • the term "projected area” is used in the same sense as the terms “projection area” and “projective area” commonly employed in the art; see, for example, James and Higgins, Fundamentals of Photographic Theory, Morgan and Morgan, New York, p. 15.
  • the present invention employs, in addition to high aspect ratio silver iodide emulsions, high aspect ratio silver bromide and bromoiodide emulsions, such as disclosed by de Cugnac et al and Ashton, cited above.
  • High aspect ratio tabular grain silver bromoiodide emulsions can be prepared by the following procedure: Into a conventional reaction vessel for silver halide precipitation, equipped with an efficient stirring mechanism, is introduced a dispersing medium. Typically the dispersing medium initially introduced into the reaction vessel is at least about 10 percent, preferably 20 to 80 percent, by weight based on total weight of the dispersing medium present in the silver bromoiodide emulsion at the conclusion of grain precipitation. Since dispersing medium can be removed from the reaction vessel by ultrafiltration during silver bromoiodide grain precipitation, as taught by U.S.
  • the volume of dispersing medium initially present in the reaction vessel can equal or even exceed the volume of the silver bromoiodide emulsion present in the reaction vessel at the conclusion of grain precipitation.
  • the dispersing medium initially introduced into the reaction vessel is preferably water or a dispersion of peptizer in water, optionally containing other ingredients, such as one or more silver halide ripening agents and/or metal dopants, more specifically described below.
  • a peptizer is initially present, it is preferably employed in a concentration of at least 10 percent, most preferably at least 20 percent, of the total peptizer present at the completion of silver bromoiodide precipitation.
  • Additional dispersing medium is added to the reaction vessel with the silver and halide salts and can also be introduced through a separate jet. It is common practice to adjust the proportion of dispersing medium, particularly to increase the proportion of peptizer, after the completion of the salt introductions.
  • a minor portion, typically less than 10 percent, of the bromide salt employed in forming the silver bromoiodide grains is initially present in the reaction vessel to adjust the bromide ion concentration of the dispersing medium at the outset of silver bromoiodide precipitation.
  • the dispersing medium in the reaction vessel is initially substantially free of iodide ions, since the presence of iodide ions prior to concurrent intro- ducton of silver and bromide salts favors the formation of thick and nontabular grains.
  • the term "substantially free of iodide ions" as applied to the contents of the reaction vessel means that there are insufficient iodide ions present as compared to bromide ions to precipitate as a separate silver iodide phase. It is preferred to maintain the iodide concentration in the reaction vessel prior to silver salt introduction at less than 0.5 mole percent of the total halide ion concentration present. If the pBr of the dispersing medium is initially too high, the tabular silver bromoiodide grains produced will be comparatively thick and therefore of low aspect ratios. It is contemplated to maintain the pBr of the reaction vessel initially at or below 1.6, preferably below 1.5.
  • pBr is defined as the negative logarithm of bromide ion concentration. pH, pCl, pI, and pAg are similarly defined for hydrogen, chloride, iodide, and silver ion concentrations, respectively.
  • bromide, and iodide salts are added to the reaction vessel by techniques well known in the precipitation of silver bromoiodide grains.
  • an aqueous solution of a soluble silver salt such as silver nitrate, is introduced into the reaction vessel concurrently with the introduction of the bromide and iodide salts.
  • the bromide and iodide salts are also typically introduced as aqueous salt solutions, such as aqueous solutions of one or more soluble ammonium, alkali metal (e.g., sodium or potassium), or alkaline earth metal (e.g., magnesium or calcium) halide salts.
  • the silver salt is at least initially introduced into the reaction vessel separately from the iodide salt.
  • the iodide and bromide salts can be added to the reaction vessel separately or as a mixture.
  • the nucleation stage of grain formation is initiated.
  • a population of grain nuclei is formed which is capable of serving as precipitation sites for silver bromide and silver iodide as the introduction of silver, bromide, and iodide salts continues.
  • the precipitation of silver bromide and silver iodide onto existing grain nuclei constitutes the growth stage of grain formation.
  • the aspect ratios of the tabular grains formed according to this invention are less affected by iodide and bromide concentrations during the growth stage than during the nucleation stage.
  • silver, bromide, and iodide salts as aqueous solutions, it is specifically preferred to introduce the silver, bromide, and iodide salts, initially or in the growth stage, in the form of fine silver halide grains suspended in dispersing medium.
  • the grain size is such that they are readily Ostwald ripened onto larger grain nuclei, if any are present, once introduced into the reaction vessel.
  • the maximum useful grain sizes will depend on the specific conditions within the reaction vessel, such as temperature and the presence of solubilizing and ripening agents.
  • Silver bromide, silver iodide, and/or silver bromoiodide grains can be introduced.
  • silver halide grains are preferably very fine--e.g., less than 0.1 pm in mean diameter.
  • the concentrations and rates of silver, bromide, and iodide salt introductions can take any convenient conventional form.
  • the silver and halide salts are preferably introduced in concentrations of from 0.1 to 5 moles per liter, although broader conventional concentration ranges, such as from 0.01 mole per liter to saturation, for example, are possible.
  • Specifically preferred precipitation techniques are those which achieve shortened precipitation times by increasing the rate of silver and halide salt introduction during the run.
  • the rate of silver and halide salt introduction can be increased either by increasing the rate at which the dispersing medium and the silver and halide salts are introduced or by increasing the concentrations of the silver and halide salts within the dispersing medium being introduced.
  • Emulsions having coefficients of variation of less than about 30 percent can be prepared.
  • the coefficient of variation is defined as 100 times the standard deviation of the grain diameter divided by the average grain diameter.
  • the concentration of iodide in the silver bromoiodide emulsions can be controlled by the introduction of iodide salts. Any conventional iodide concentration can be employed. Even very small amounts of iodide--e.g., as low as 0.05 mole percent--are recognized in the art to be beneficial. In their preferred form the emulsions of the present invention incorporate at least about 0.1 mole percent iodide. Silver iodide can be incorporated into the tabular silver bromoiodide grains up to its solubility limit in silver bromide at the temperature of grain formation.
  • silver iodide concentrations of up to about 40 mole percent in the tabular silver bromoiodide grains can be achieved at precipitation temperatures of 90°C.
  • precipitation temperatures can range down to near ambient room temperatures--e.g.-, about 30°C. It is generally preferred that precipitation be undertaken at temperatures in the range of from 40 to 80°C.
  • the relative proportion of iodide and bromide salts introduced into the reaction vessel during precipitation can be maintained in a fixed ratio to form a substantially uniform iodide profile in the tabular silver bromoiodide grains or varied to achieve differing photographic effects. It has been recognized that specific photographic advantages result from increasing the proportion of iodide in annular or otherwise laterally displaced regions of high aspect ratio tabular grain silver bromoiodide emulsions as compared to central regions of the tabular grains.
  • iodide concentrations in the central regions of from 0 to 5 mole percent, with at least one mole percent higher iodide concentrations in the laterally surrounding annular regions up to the solubility limit of silver iodide in silver bromide, preferably up to about 20 mole percent and optimally up to about 15 mole percent.
  • iodide concentrations in the central regions of from 0 to 5 mole percent, with at least one mole percent higher iodide concentrations in the laterally surrounding annular regions up to the solubility limit of silver iodide in silver bromide, preferably up to about 20 mole percent and optimally up to about 15 mole percent.
  • the tabular silver bromoiodide grains can exhibit substantially uniform or graded iodide concentration profiles and that the gradation can be controlled, as desired, to favor higher iodide concentrations internally or at or near the surfaces of the tabular silver bromoiodide grains.
  • High aspect ratio tabular grain silver bromide emulsions lacking iodide are also useful in the multicolor photographic elements of this invention and can be prepared by the process described above modified to exclude iodide.
  • High aspect ratio tabular grain silver bromide emulsions can alternatively be prepared following a procedure similar to that employed by deCugnac et al, cited above.
  • High aspect ratio silver bromide emulsions containing square and rectangular grains can be prepared as taught by U.S. Patent 4,386,215. In this process cubic seed grains having an edge length of less than 0.15 pm are employed.
  • the emulsion While maintaining the pAg of the seed grain emulsion in the range of from 5.0 to 8.0, the emulsion is ripened in the substantial absence of nonhalide silver ion complexing agents to produce tabular silver bromide grains having an average aspect ratio of at least 8.5:1. Still other preparations of high aspect ratio tabular grain silver bromide emulsions lacking iodide are illustrated in the examples.
  • High aspect ratio tabular grain emulsions of other silver halide compositions can also be used in the multicolor photographic elements of this invention.
  • Such emulsions and their preparation are also disclosed in U.S. Patents 4,399,215 and 4,400,463.
  • silver halide emulsions containing high aspect ratio silver iodide tabular grains of face centered cubic crystal structure used in the multicolor photographic elements of this invention and can be prepared by modifying conventional double-jet silver halide precipitation procedures.
  • pAg is the negative logarithm of silver ion concentration.
  • Silver halide emulsions containing high aspect ratio silver iodide tabular grains of a hexagonal crystal structure, as exhibited by B phase silver iodide can be prepared by double-jet precipitation procedures on the halide side of the equivalence point. Useful parameters for precipitation are illustrated in the Examples below.
  • Zharkov et al cited above discloses the preparation of silver iodide emulsions containing tabular grains of B phase crystal structure by ripening in the presence of a ammonia and an excess of potassium iodide.
  • High aspect ratio tabular grain emulsions useful in the practice of this invention can have extremely high average aspect ratios.
  • Tabular grain average aspect ratios can be increased by increasing average grain diameters. This can produce sharpness advantages, but maximum average grain diameters are generally limited by granularity requirements for a specific photographic application.
  • Tabular grain average aspect ratios can also or alternatively be increased by decreasing average grain thicknesses. When silver coverages are held constant, decreasing the thickness of tabular grains generally improves granularity as a direct function of increasing aspect ratio.
  • the maximum average aspect ratios of the tabular grain emulsions employed in the multicolor photographic elements of this invention are a function of the maximum average grain diameters acceptable for the specific photographic application and the minimum attainable tabular grain thicknesses which can be produced.
  • Average aspect ratios as high as 50:1 or even 100:1 for silver chloride tabular grains, optionally containing bromide and/or iodide, can be prepared as taught by U.S. Patent 4,400,463, cited above. Because of the exceptionally thin silver iodide tabular grains which can be obtained, high average aspect ratios ranging up to 100:1 can be readily achieved, regardless of whether the silver iodide is in a face centered cubic (y phase) or hexagonal (S phase) crystal structure. Emulsions containing silver iodide tabular grains of hexagonal crystal structure of even higher average aspect ratios, ranging up to 200:1, or even 500:1, are contemplated.
  • Modifying compounds can be present during tabular grain precipitation. Such compounds can be initially in the reaction vessel or can be added along with one or more of the salts according to conventional procedures. Modifying compounds, such as compounds of copper, thallium, lead, bismuth, cadmium, zinc, middle chalcogens (i.e., sulfur, selenium, and tellurium), gold, and Group VIII noble metals, can be present during silver halide precipitation, as illustrated by U.S. Patents 1,195,432, 1,951,933, 2,448,060, 2,628,167, 2,950,972, 3,488,709, 3,737,313, 3,772,031, and 4,269,927, and Research Disclosure, Vol. 134, June 1975, Item 13452.
  • the individual silver and halide salts can be added to the reaction vessel through surface or subsurface delivery tubes by gravity feed or by delivery apparatus for maintaining control of the rate of delivery and the pH, pBr, and/or pAg of the reaction vessel contents, as illustrated by U.S. Patents 3,821,002 and 3,031,304 and Claes et al, Photographische Korrespondenz, Band 102, Number 10, 1967, p. 162.
  • specially constructed mixing devices can be employed, as illustrated by U.S. Patents 2,996,287, 3:342,605, 3,415,650, 3,785,777, 4,147,551, and 4,171,224, U.K. Patent Application 2,022,431A, German OLS 2,555,364 and 2,556,885, and Research Disclosure, Volume 166, February 1978, Item 16662.
  • a dispersing medium is initially contained in the reaction vessel.
  • the dispersing medium is comprised of an aqueous peptizer suspension.
  • Peptizer concentrations of from 0.2 to about 10 percent by weight, based on the total weight of emulsion components in the reaction vessel, can be employed. It is common practice to maintain the concentration of the peptizer in the reaction vessel in the range of below about 6 percent, based on the total weight, prior to and during silver halide formation and to adjust the emulsion vehicle concentration upwardly for optimum coating characteristics by delayed, supplemental vehicle additions.
  • the emulsion as initially formed will contain from about 5 to 50 grams of peptizer per mole of silver halide,most preferably about 10 to 30 grams of peptizer per mole of silver halide. Additional vehicle can be added later to bring the concentration up to as high as 1000 grams per mole of silver halide. Preferably the concentration of vehicle in the finished emulsion is above 50 grams per mole of silver halide. When coated and dried in forming a photographic element the vehicle preferably forms about 30 to 70 percent by weight of the emulsion layer.
  • Vehicles which include both binders and peptizers
  • Preferred peptizers are hydrophilic colloids, which can be employed alone or in combination with hydrophobic materials, and are illustrated by Research Disclosure, Vol. 176, December 1978, Item 17643, Paragraph IX.
  • the hydrophobic materials need not be present in the reaction vessel during silver halide precipitation, but rather are conventionally added to the emulsion prior to coating.
  • the vehicle materials including particularly the hydrophilic colloids, as well as the hydrophobic materials useful in combination therewith can be employed not only in the emulsion layers of the photographic elements of this invention, but also in other layers, such as overcoat layers, interlayers and layers positioned beneath the emulsion layers.
  • Gram ripening can occur during the preparation of high aspect ratio tabular grain silver halide emulsions useful in the practice of the present invention, and it is preferred that grain ripening occur within the reaction vessel during at least silver bromoiodide grain formation.
  • Known silver halide solvents are useful in promoting ripening. For example, an excess of bromide ions, when present in the reaction vessel, is known to promote ripening.
  • the bromide salt solution run into the reaction vessel can itself promote ripening.
  • Other ripening agents can also be employed and can be entirely contained within the dispersing medium in the reaction vessel before silver and halide salt addition, or they can be introduced into the reaction vessel along with one or more of the halide salt, silver salt, or peptizer.
  • the ripening agent can be introduced independently during halide and silver salt additions.
  • ripening agents are those containing sulfur.
  • Thiocyanate salts can be used, such as alkali metal, most commonly sodium and potassium, and ammonium thiocyanate salts. While any conventional quantity of the thiocyanate salts can be introduced, preferred concentrations are generally from about 0.1 to 20 grams of thiocyanate salt per mole of silver halide.
  • Illustrative prior teachings of employing thiocyanate ripening agents are found in U.S. Patents 2,222,264, 2,448,534, and 3,320,069.
  • conventional thioether ripening agents such as those disclosed in U.S. Patents 3,271,157, 3,574,628, and 3,737,313, can be employed.
  • the high aspect ratio tabular grain emulsions are preferably washed to remove soluble salts.
  • the soluble salts can be removed by decanta - tion, filtration, and/or chill setting and leaching, as illustrated by U.S. Patents 2,316,845 and 3,396,027; by coagulation washing, as illustrated by U.S. Patents 2,618,556, 2,614,928, 2,565,418, 3,241,969, and 2,489,341, and U.K. Patents 1,305,409 and 1,167,159; by centrifugation and decantation of a coagulated emulsion, as illustrated by U.S.
  • the emulsions, with or without sensitizers, can be dried and stored prior to use as illustrated by Research Disclosure, Vol. 101, September 1972, Item 10152. Washing is particularly advantageous in terminating ripening of the tabular grains after the completion of precipitation to avoid increasing their thickness and reducing their aspect ratio.
  • the high aspect ratio tabular grain emulsions can be shelled to produce core-shell emulsions by procedures well known to those skilled in the art.
  • Any photographically useful silver salt can be employed in forming shells on the high aspect ratio tabular grain emulsions prepared by the present process.
  • Techniques for forming silver salt shells are illustrated by U.S. Patents 3,367,778, 3,206,313, 3,317,322, and 3,917,485. Since conventional techniques for shelling do not favor the formation of high aspect ratio tabular grains, as shell growth proceeds the average aspect ratio of the emulsion declines. If conditions favorable for tabular grain formation are present in the reaction vessel during shell formation, shell growth can occur preferentially on the outer edges of the grains so that aspect ratio need not decline.
  • tabular silver halide grains satisfying the thickness and diameter criteria for aspect ratio account for at least 50 percent of the total projected area of the total silver halide grain population
  • further advantages can be realized by increasing the proportion of such tabular grains present.
  • at least 70 percent (optimally at least 90 percent) of the total projected area is provided by tabular silver halide grains meeting the thickness and diameter criteria. While minor amounts of nontabular grains are fully compatible with many photographic applications, to achieve the full advantages of tabular grains the proportion of tabular grains can be increased.
  • radiation-sensitive silver halide emulsions other than high aspect ratio tabular grain emulsions are employed in the multicolor photographic elements of this invention, they can be chosen from any conventional emulsion heretofore employed in multicolor photographic elements.
  • Illustrative emulsions, their preparation and chemical sensitization are disclosed in Research Disclosure, Item 17643, cited above, Paragraph I, Emulsion preparation and types and Paragraph III, chemical sensitization,
  • Silver iodide emulsions other than high aspect ratio tabular grain emulsions to the extent employed in various forms of the multicolor photographic elements of this invention can be precipitated by procedures generally similar to those for preparing the high aspect ratio tabular grain silver iodide emulsions, described above, but without taking the precautions indicated to produce high average aspect ratios.
  • such emulsions can be prepared by the techniques disclosed by Byerley and Hirsch, Zharkov et al, and Daubendiek, "AgI Precipitations: Effects of pAg on Crystal Growth (PB)", each cited above.
  • the silver iodide emulsions employed in the multicolor photographic elements of this invention can be sensitized by conventional techniques.
  • a preferred chemical sensitization technique is to deposit a silver salt epitaxially onto the tabular silver iodide grains.
  • the epitaxial deposition of silver chloride onto silver iodide host grains is taught by U.S. Patents 4,094,684 and 4,142,900, and the analogous deposition of silver bromide onto silver iodide host grains is taught by U.K. Patent Application 2,053,499A, each cited above.
  • the high aspect ratio tabular silver iodide grains as host grains for epitaxial deposition.
  • the terms "epitaxy” and “epitaxial” are employed in their art recognized sense to indicate that the silver salt is in a crystalline form having its orientation controlled by the host tabular grains.
  • the silver salt epitaxy is preferably substantially excluded in a controlled manner from at least a portion of the major crystal faces of the tabular host grains.
  • the tabular host grains direct epitaxial deposition of silver salt to their edges and/or corners.
  • epitaxially deposited silver salt it is specifically preferred to confine epitaxially deposited silver salt to less than half the area of the major crystal faces of the tabular grains, most preferably less than 25 percent, and in certain forms, such as corner epitaxial silver salt deposits, optimally to less than 10 or even 5 percent of the area of the major crystal faces of the tabular grains.
  • epitaxial deposition has been observed to commence on the edge surfaces of the tabular grains. Thus, where epitaxy is limited, it may be otherwise confined to selected edge sensitization sites and effectively excluded from the major crystal faces.
  • the epitaxially deposited silver salt can be used to provide sensitization sites on the tabular host grains.
  • sites of epitaxial deposition it is possible to achieve selective site sensitization of the tabular host grains.
  • Sensitization can be achieved at one or more ordered sites on the tabular host grains.
  • ordered it is meant that the sensitization sites bear a predictable, nonrandom relationship to the major crystal faces of the tabular grains and, preferably, to each other.
  • epitaxial deposition with respect to the major crystal faces of the tabular grains it is possible to control both the number and lateral spacing of sensitization sites.
  • selective site sensitization can be detected when the silver iodide grains are exposed to radiation to which they are sensitive and surface latent image centers are produced at sensitization sites. If the grains bearing latent image centers are entirely developed, the location and number of the latent image centers cannot be determined. However, if development is arrested before development has spread beyond the immediate vicinity of the latent image center, and the partially developed grain is then viewed under magnification, the partial development sites are clearly visible. They correspond generally to the sites of the latent image centers which in turn generally correspond to the sites of sensitizaton.
  • the sensitizing silver salt that is deposited onto the host tabular grains at selected sites can be generally chosen from among any silver salt capable of being epitaxially grown on a silver halide grain and heretofore known to be useful in photography.
  • the anion content of the silver salt and the tabular silver halide grains differ sufficiently to permit differences in the respective crystal structures to be detected. It is specifically preferred to choose the silver salts from among those heretofore known to be useful in forming shells for core-shell silver halide emulsions.
  • the silver salts can include other silver salts known to be capable of precipitating onto silver halide grains, such as silver thiocyanate, silver cyanide, silver carbonate, silver ferricyanide, silver arsenate or arsenite, and silver chromate.
  • Silver chloride is a specifically preferred sensitizer.
  • the silver salt can usefully be deposited in the presence of any of the modifying compounds described above in connection with the tabular silver halide grains. Some iodide from the host grains may enter the silver salt epitaxy.
  • the host grains can contain anions other than iodide up to their solubility limit in silver iodide, and, as employed herein, the term "silver iodide grains" is intended to include such host grains.
  • any conventional technique for chemical sensitization following controlled site epitaxial deposition can be employed.
  • chemical sensitization should be undertaken based on the composition of-the silver salt deposited rather than the composition of the host tabular grains, since chemical sensitization is believed to occur primarily at the silver salt deposition sites or perhaps immediately adjacent thereto.
  • noble metal e.g., gold
  • middle chalcogen e.g., sulfur, selenium, and/or tellurium
  • reduction sensitization as well as combinations thereof are disclosed in Research Disclosure, Item 17643, Paragraph III, cited above.
  • High aspect ratio tabular grain emulsions other than the silver iodide emulsions discussed above can be chemically sensitized by procedures similar to those employed in chemically sensitizing emulsions conventionally employed in multicolor photographic elements, described above. As is apparent from Ashton, cited above, extremely high speeds and highly improved speed-granularity relationships can be achieved when the emulsions are substantially optimally sensitized. In one preferred form chemical sensitization is undertaken after spectral sensitization. Similar results have also been achieved in some instances by introducing other adsorbable materials, such as finish modifiers, into the emulsion prior to chemical sensitization.
  • thiocyanates during chemical sensitization in concentrations of from about 2 X 10- 3 to 2 mole percent, based on silver, as taught by U.S. Patent 2,462,361.
  • Other ripening agents can be used during chemical sensitization.
  • Still a third approach, capable of being practiced independently of, but compatible with, the two approaches described above, is to deposit silver salts epitaxially on the high aspect ratio tabular grains, as is taught by U.S. Patent 4,400,463, cited above.
  • the silver iodide emulsions intended to record blue light exposures can, but need not, be spectrally sensitized in the blue portion of the spectrum.
  • Silver bromide and silver bromoiodide emulsions containing nontabular grains and relatively thick tabular grains can be employed to record blue light without incorporating blue sensitizers, .although their absorption efficiency is much higher when blue sensitizers are present.
  • the silver halide emulsions, regardless of composition, intended to record minus blue light are spectrally sensitized to red or green light by the use of spectral sensitizing dyes.
  • the silver halide emulsions incorporated in the multicolor photographic elements of this invention can be spectrally sensitized with dyes from a variety of classes, including the polymethine dye class, which classes include the cyanines, merocyanines, complex cyanines and merocyanines (i.e., tri-, tetra-, and poly-nuclear cyanines and merocyanines), oxonols, hemioxonols, styryls, merostyryls, and streptocyanines, such as illustrated by Research Disclosure, Item 17643, cited above, Paragraph IV.
  • the polymethine dye class which classes include the cyanines, merocyanines, complex cyanines and merocyanines (i.e., tri-, tetra-, and poly-nuclear cyanines and merocyanines), oxonols, hemioxonols, styryls
  • One or more spectral sensitizing dyes may be used. Dyes with sensitizing maxima at wavelengths throughout the visible spectrum and with a great variety of spectral sensitivity curve shapes are known. The choice and relative proportions of dyes depends upon the region of the spectrum to which sensitivity is desired and upon the shape of the spectral sensitivity curve desired. Dyes with overlapping spectral sensitivity curves will often yield in combination a curve in which the sensitivity at each wavelength in the.area of overlap is approximately equal to the sum of the sensitivities of the individual dyes. Thus, it is possible to use combinations of dyes with different maxima to achieve a spectral sensitivity curve with a maximum -intermediate to the sensitizing maxima of the individual dyes.
  • Combinations of spectral sensitizing dyes can be used which result in supersensitization--that is, spectral sensitization that is 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, "Review of the Mechanisms of Supersensitization", Photographic Science and Engineering, Vol. 18, 1974, pp. 418-430.
  • Spectral sensitizing dyes also affect the emulsions in other ways. Spectral sensitizing dyes can also function as antifoggants or stabilizers, development accelerators or inhibitors, and halogen acceptors or electron acceptors, as disclosed in U.S. Patents 2,131,038 and 3,930,860.
  • dyes can be employed in spectrally sensitizing the emulsion layers containing nontabular or low aspect ratio tabular silver halide grains.
  • adsorb spectral sensitizing dye to the grain surfaces of the high aspect ratio tabular grain emulsions in a substantially optimum amount--that is, in an amount sufficient to realize at least 60 percent of the maximum photographic speed attainable from the grains under contemplated conditions of exposure.
  • the quantity of dye employed will vary with the specific dye or dye combination chosen as well as the size and aspect ratio of the grains.
  • Useful blue spectral sensitizing dyes for high aspect ratio tabular grain silver bromide and silver bromoiodide emulsions can be selected from any of the dye classes known to yield spectral sensitizers.
  • Polymethine dyes such as cyanines, merocyanines, hemicyanines, hemioxonols, and merostyryls, are preferred blue spectral sensitizers.
  • useful blue spectral sensitizers can be selected from among these dye classes by their absorption characteristics--i.e., hue. There are, however, general structural correlations that can serve as a guide in selecting useful blue sensitizers. Generally the shorter the methine chain, the shorter the wavelength of the sensitizing maximum.
  • alkyl groups and moieties contain from 1 to 20 carbon atoms, preferably from 1 to 8 carbon atoms.
  • Aryl groups and moieties contain from 6 to 15 carbon atoms and are preferably phenyl or naphthyl groups or moieties.
  • Preferred cyanine blue spectral sensitizers are monomethine cyanines; however, useful cyanine blue spectral sensitizers can be selected from among those of Formula 1.
  • Z 1 and Z 2 may be the same or different and each represents the elements needed to complete a cyclic nucleus derived from basic heterocyclic nitrogen compounds such as oxazoline, oxazole, benzoxazole, the naphthoxazoles (e.g., naphth-[2,1-d]oxazole, naphth[2,3-d]oxazole, and naphth-[1,2-d]oxazole), thiazoline, thiazole, benzothiazole, the naphthothiazoles (e.g., naphtho[2,1-d]-thiazole), the thiazoloquinolines (e.g., thiazolo-[4,5-b]quinoline), selenazoline, selenazole, benzoselenazole, the naphthoselenazoles (e.g., naphtho-[1,2-d]selenazole), 3H-indole (e.g., 3,3-
  • Preferred merocyanine blue spectral sensitizers are zero methine merocyanines; however, useful merocyanine blue spectral sensitizers can be selected from among those of Formula 2.
  • G 1 , G 2 , G 3 , G 4 , and n are as defined in Formula 4.
  • Spectral sensitization can be undertaken at any stage of emulsion preparation heretofore known to be useful. Most commonly spectral sensitization is undertaken in the art subsequent to the completion of chemical sensitization. However, it is specifically recognized that spectral sensitization can be undertaken alternatively concurrently with chemical sensitization, can entirely precede chemical sensitization, and can even commence prior to the completion of silver halide grain precipitation, as taught by U.S. Patents 3,628,960, and 4,225,666. The latter teaches
  • the spectral sensitizing dye can be added to the emulsion after 80 percent of the silver halide has been precipitated. Sensitization can be enhanced by pAg adjustment, including variation in pAg which completes one or more cycles, during chemical and/or spectral sensitization. A specific example of pAg adjustment is provided by Research Disclosure, Vol. 181, May 1979, Item 18155.
  • the multicolor photographic elements of this invention can include a variety of features which are conventional in multicolor photographic elements and therefore require no detailed description.
  • the multicolor photographic elements of this invention can employ conventional features, such as disclosed in Research Disclosure, Item 17643, cited above.
  • Optical brighteners can be introduced, as disclosed by Paragraph V.
  • Antifoggants and sensitizers can be incorporated, as disclosed by Paragraph VI.
  • Absorbing and scattering materials can be employed in the emulsions of the invention and in separate layers of the photographic elements, as described in Paragraph VIII.
  • Hardeners can be incorporated, as disclosed in Paragraph X.
  • Coating aids as described in Paragraph XI, and plasticizers and lubricants, as described in Paragraph XII, can be present.
  • Antistatic layers as described in Paragraph XIII, can be present.
  • Methods of addition of addenda are described in Paragraph XIV.
  • Matting agents can be incorporated, as described in Paragraph X VI.
  • Developing agents and development modifiers can, if desired, be incorporated, as described in Paragraphs XX and XXI.
  • Silver halide emulsion layers as well as interlayers, overcoats, and subbing layers, if any, present in the photographic elements can be coated and dried as described in Paragraph XV.
  • the layers of the photographic elements can be coated on a variety of supports.
  • Typical photographic supports include polymeric film, wood fiber--e.g., paper, metallic sheet and foil, glass and ceramic supporting elements provided with one or more subbing layers to enhance the adhesive, antistatic, dimensional, abrasive, hardness, frictional, antihalation and/or other properties of the support surface.
  • Typical of useful paper and polymeric film supports are those disclosed in Research Disclosure, Item 17643, cited above, Paragraph XVII.
  • the multicolor photographic elements can be used to form dye images therein through the selective destruction or formation of dyes, such as illustrated by Research Disclosure, Item 17643, cited above Paragraph VII.
  • the photographic elements can be used to form dye images by employing developers containing dye image formers, such as color couplers, or by incorporating the dye image formers directly in the multicolor photographic element.
  • Dye-forming couplers can be incorporated in the photographic elements.
  • the dye-forming couplers can be incorporated in different amounts to achieve differing photographic effects. For example, limiting the concentration of coupler in relation to the silver coverage to less than normally employed amounts in faster and intermediate speed emulsion layers.
  • the dye-forming couplers are commonly chosen to form subtractive primary (i.e., yellow, magenta and cyan) image dyes and are nondiffusible, colorless couplers, such as two and four equivalent couplers of the open chain ketomethylene, pyrazolone, pyrazolotriazole, pyrazolobenzimidazole, phenol and naphthol type hydrophobically ballasted for incorporation in high-boiling organic (coupler) solvents.
  • Dye-forming couplers of differing reaction rates in single or separate layers can be employed to achieve desired effects for specific photographic applications.
  • the dye-forming couplers upon coupling can release photographically useful fragments, such as development inhibitors or accelerators, bleach accelerators, developing agents, silver halide solvents, toners, hardeners, fogging agents, antifoggants, competing couplers, chemical or spectral sensitizers and desensitizers.
  • photographically useful fragments such as development inhibitors or accelerators, bleach accelerators, developing agents, silver halide solvents, toners, hardeners, fogging agents, antifoggants, competing couplers, chemical or spectral sensitizers and desensitizers.
  • Dye-forming couplers and nondye-forming compounds which upon coupling release a variety of photographically useful groups are described by U.S. Patent 4,248,962.
  • DIR compounds which do not form dye upon reaction with oxidized color-developing agents can be employed.
  • DIR compounds which oxidatively cleave can be employed.
  • the photographic elements can incorporate colored dye-forming couplers, such as those employed to form integral masks for negative color images.
  • the photographic elements can independently include image dye stabilizers.
  • Dye images can be formed or amplified by processes which employ in combination with a dye-image-generating reducing agent an inert transition metal ion complex oxidizing agent and/or a peroxide oxidizing agent, as illustrated by Research Disclosure, Item 17643, cited above, Paragraph XIX.
  • the photographic elements can produce dye images through the selective destruction of dyes or dye precursors, such as silver-dye-bleach processes.
  • the photographic elements can be processed to form dye images which correspond to or are reversals of the silver halide rendered selectively developable by imagewise exposure.
  • Reversal dye images can be formed in photographic elements having differentially spectrally sensitized silver halide layers by black-and-white development followed by i) where the elements lack incorporated dye image formers, sequential reversal color development with developers containing dye image formers, such as color couplers; ii) where the elements contain incorporated dye image formers, such as color couplers, a single color development step, as illustrated by the Kodak Ektachrome E4 and E6 and Agfa processes described in British Journal of Photography Annual, 1977, pp. 194-197, and British Journal of Photography, August 2, 1974, pp. 668-669; and iii) where the photographic elements contain bleachable dyes, silver-dye-bleach processing, as illustrated by the Cibachrome P-10 and P-18 processes described in the British Journal of Photography Annual, 1977, pp. 209-212.
  • the photographic elements can be adapted for direct color reversal processing (i.e., production of reversal color images without prior black-and-white development), as illustrated by U.K. Patents 1,075,385 and 1,132,736, U.S. Patents 3,243,294, 3,647,452, 3,457,077, 3,467,520, German Patents 1,257,570. 1,259,700, and 1,259,701, and German OLS 2,005,091.
  • Dye images which correspond to the silver halide rendered selectively developable by imagewise exposure can be produced by processing, as illustrated by the Kodacolor C-22, the Kodak Flexicolor C-41 and the Agfacolor processes described in British Journal of Photography Annual, 1977, pp. 201-205.
  • the photographic elements can also be processed by the Kodak Ektaprint-3 and -300 processes as described in Kodak Color Dataguide, 5th Ed., 1975, pp. 18-19, and the Agfa color process as described in British Journal of Photography Annual, 1977, pp. 205-206, such processes being particularly suited to processing color print materials, such as resin-coated photographic papers, to form positive dye images.
  • the multicolor photographic elements of this invention produce multicolor images from combinations of subtractive primary imaging dyes.
  • Such photographic elements are comprised of a support and typically at least a triad of superimposed silver halide emulsion layers for separately recording blue, green, and red exposures as yellow, magenta, and cyan dye images, respectively.
  • Exposures can be of any conventional nature and are illustrated by Research Disclosure, 17643, cited above, Paragraph XVIII.
  • the present invention generally embraces any multicolor photographic element of this type including at least one silver halide emulsion layer containing high aspect ratio silver iodide tabular grains, additional advantages can be realized when additional high aspect ratio tabular grain emulsion layers are employed.
  • Multicolor photographic elements are often described in terms of color-forming layer units. Most commonly multicolor photographic elements contain three superimposed color-forming layer units each containing at least one silver halide emulsion layer capable of recording exposure to a different third of the spectrum and capable of producing a complementary subtractive primary dye image. Thus, blue, green, and red recording color-forming layer units are used to produce yellow, magenta, and cyan dye images, respectively.
  • Dye imaging materials need not be present in any color-forming layer unit, but can be entirely supplied from processing solutions. When dye imaging materials are incorporated in the photographic element, they can be located in an emulsion layer or in a layer located to receive oxidized developing or electron transfer agent from an adjacent emulsion layer of the same color-forming layer unit.
  • scavengers can be located in the emulsion layers themselves, as taught by U.S. Patent 2,937,086 and/or in interlayers between adjacent color-forming layer units, as illustrated by U.S. Patent 2,336,327.
  • Lippmann emulsions particularly silver chloride and silver bromide emulsions of grain diameters of less than 0.1 um, blended with the silver iodide emulsions or in separate interlayers separating the silver iodide emulsion layers from the silver halide emulsion layers to act as scavengers for iodide ions released on development.
  • -Suitable Lippmann emulsions are disclosed by U.S. Patents 3,892,572 and 3,737,317.
  • each color-forming layer unit can contain a single emulsion layer, two, three, or more emulsion layers differing in photographic speed are often incorporated in a single color-forming layer unit.
  • the desired layer order arrangement does not permit multiple emulsion layers differing in speed to occur in a single color-forming layer unit, it is common practice to provide multiple (usually two or three) blue, green, and/or red recording color-forming layer units in a single photographic element.
  • the multicolor photographic elements of this invention can take any convenient form consistent with the requirements indicated above. Any of the six possible layer arrangements of Table 27a, p. 211, disclosed by Gorokhovskii, Spectral Studies of the Photographic Process, Focal Press, New York, can be employed. To provide a simple, specific illustration, it is possible to add to a conventional multicolor sliver halide photographic element during its preparation one or more blue recording emulsion layers containing high aspect ratio tabular silver iodide grains positioned to receive exposing radiation prior to the remaining emulsion layers. However, in most instances it is preferrred to substitute one or more blue recording emulsion layers containing high aspect ratio tabular silver iodide grains for conventional blue recording emulsion layers, optionally in combination with layer order arrangement modifications.
  • the multicolor photographic elements of this invention use at least one emulsion layer containing high aspect ratio tabular silver iodide grains to record imagewise exposures to the blue portion of the visible spectrum. Since silver iodide possesses a very high level of absorption of blue light in the spectral region of less than about 430 nanometers, in one application of this invention the silver iodide grains can be relied upon to absorb blue light of 430 nanometers or less in wavelength without the use of a blue spectral sensitizing dye.
  • a silver iodide tabular grain is capable of absorbing most of the less than 430 nanometer blue light incident upon it when it is at least about 0.1 pm in thickness and substantially all of such light when it is at least about 0.15 pm in thickness.
  • the blue light absorbing capability of tabular silver iodide grains is in direct contrast to the light absorbing capability of the high aspect ratio tabular grain emulsions of other silver halide compositions, such as those disclosed by Ashton, cited above.
  • the latter exhibit markedly lower levels of blue light absorption even at increased thicknesses.
  • the tabular grain thicknesses of emulsions of other halide compositions take into account that the emulsion layer will normally be coated with a conventional silver coverage, which is sufficient to provide many layers of superimposed tabular grains, whereas the 0.1 and 0.15 pm thicknesses above are for a single grain.
  • tabular silver iodide grains be used without blue spectral sensitizers, but they permit blue recording emulsion layers to be reduced in thickness (thereby increasing sharpness) and reduced in silver coverage.
  • tabular grain silver iodide emulsions provided minimal grain thicknesses are satisfied, absorb blue light as a function of the projected area which they present to exposing radiation. This is a- fundamental distinction over other silver halides, such as silver bromide and silver bromoiodide, which, without the assistance of spectral sensitizers, absorb blue light as a function of their volume.
  • the high aspect ratio tabular grain silver iodide emulsions are more efficient in absorbing blue light than high aspect ratio tabular grains of differing halide composition, they are more efficient than conventional silver iodide emulsions containing nontabular grains or lower average aspect ratio tabular grains.
  • conventional silver iodide emulsions present lower projected areas and hence are capable of reduced blue light absorption. They also capture fewer photons per grain and are of lower photographic speed than the high aspect ratio tabular silver iodide grain emulsions, other parameters being comparable.
  • the conventional silver iodide grains are increased to match the projected areas presented by the high aspect ratio tabular grain silver iodide emulsions, the conventional grains become much thicker than the high aspect ratio tabular silver iodide grains, require higher silver coverages to achieve comparable blue absorption, and are in general less efficient.
  • high aspect ratio tabular silver iodide grain emulsions can be used to record blue light exposures without the use of spectral senstiz- ing dyes, it is appreciated that the native blue absorption of silver iodide is not high over the entire blue region of the spectrum. To achieve a photographic response over the entire blue region of the spectrum one or more blue sensitizing dyes are employed in combination with such emulsions.
  • the dye preferably exhibits an absorption peak of a wavelength longer than 430 nanometers so that the absorption of the silver iodide forming the tabular grains and the blue sensitizing dye together extend over a larger wavelength range of the blue spectrum.
  • silver iodide and a blue sensitizing dye can be employed in combination to provide a photographic response over the entire blue portion of the spectrum
  • the silver iodide grains are chosen as described above for recording blue light efficiently in the absence of spectral sensitizing dye, the result is a highly unbalanced sensitivity.
  • the silver iodide grains absorb substantially all of the blue light of a wavelength of less than 430 nanometers while the blue sensitizing dye absorbs only a fraction of the blue light of a wavelength longer than 430. To obtain a balanced sensitivity over the entire blue portion of the spectrum the efficiency of the silver iodide grains.in absorbing light of less than 430 nm of wavelength can be reduced.
  • the optimum thickness of the tabular grains for a specific application is selected so that absorption above and below 430 nanometers is substantially matched. This will vary as a function of the spectral sensitizing dye or dyes employed.
  • a multicolor photographic element can be constructed incorporating a uniform distribution of a redox catalyst in addition to at least one layer containing high aspect ratio tabular silver iodide grains.
  • a redox catalyst in addition to at least one layer containing high aspect ratio tabular silver iodide grains.
  • Patent 4,089,685 specifically illustrates a useful redox system in which a peroxide oxidizing agent and a dye-image-generating reducing agent, such as a color developing agent or redox dye- releasor, react imagewise at available, unpoisoned catalyst sites within a photographic element.
  • U.S. Patent 4,158,565 discloses the use of silver iodide host grains bearing silver chloride epitaxy in such a redox amplification system.
  • multicolor photographic elements of this invention are their improved speed-granularity relationship. As taught by Ashton, cited above, substantially optimally chemically and spectrally sensitized high aspect ratio tabular grain silver halide emulsions can exhibit unexpected improvements in the speed-granularity relationships of multicolor photographic elements.
  • the maximum speed obtained at optimum sensitization increases linearly with increasing grain size.
  • the number of absorbed quanta necessary to render a grain developable is substantially independent of grain size, but the density that a given number of grains will produce upon development is directly related to their size. If the aim is to produce a maximum density of 2, for example, fewer grains o£ 0.4 pm as compared to 0.2 pm in average diameter - are required to produce that density. Less radiation is required to render fewer grains developable.
  • granularity is most commonly measured as rms (root mean square) granularity, which is defined as the standard deviation of density within a viewing microaperture (e.g., 24 to 48 pm).
  • FIG. 7 a schematic plot of speed versus granularity is shown for five silver halide emulsions 1, 2, 3, 4, and 5 of the same composition, but differing in grain size, each similarly sensitized, identically coated, and identically processed. While the individual emulsions differ in maximum speed and granularity, there is a predictable linear relationship between the emulsions, as indicated by the speed-granularity line A. All emulsions which can be joined along the line A exhibit the same speed-granularity relationship. Emulsions which exhibit true improvements in sensitivity lie above the speed-granularity line A.
  • emulsions 6 and 7, which lie on the common speed-granularity line B, are superior in their speed-granularity relationships to any one of the emulsions 1 through 5.
  • Emulsion 6 exhibits a higher speed than emulsion 1, but no higher granularity.
  • Emulsion 6 exhibits the same speed as emulsion 2, but at a much lower granularity.
  • Emulsion 7 is of higher speed than emulsion 2, but is of a lower granularity than emulsion 3, which is of lower speed than emulsion 7.
  • Emulsion 8, which falls below the speed-granularity line A exhibits the poorest speed-granularity relationship shown in Figure 7.
  • emulsion 8 exhibits the highest photographic speed of any of the emulsions, its speed is realized only at a disproportionate increase in granularity.
  • the emulsions contained in the multicolor elements be substantially optimally chemically and spectrally sensitized, although, subject to the considerations discussed above, the silver iodide emulsions need not be spectrally sensitized.
  • substantially optimally it is meant that the emulsions preferably achieve speeds of at least 60 percent of the maximum log speed attainable from the grains in the spectral region of sensitization under the contemplated conditions of use and processing.
  • Log speed is herein defined as 100(1-log E), where E is measured in meter-candle-seconds at a density of 0.1 above fog.
  • Substantially optimum chemical and spectral sensitization of high aspect ratio tabular grain silver halide emulsions, particularly silver bromoiodide emulsions, is generally taught by Item 22534.
  • Such emulsions can exhibit speed-granularity relationships superior to conventional (low aspect ratio tabular grain or nontabular grain) emulsions.
  • Illingsworth U.S. Patent 3,320,069 particularly illustrates conventional silver bromoiodide e mul- sions of outstanding speed-granularity relationship contemplated for use in the multicolor photographic elements of this invention.
  • Loss of image sharpness resulting from light scattering generally increases with increasing thickness of a silver halide emulsion layer. The reason for this can be appreciated by reference to Figure 8. If a photon of light 1 is deflected by a silver halide grain at a point 2 by an angle 8 measured as a declination from its original path and is thereafter absorbed by a second silver halide grain at a point 3 after traversing a thickness t 1 of the emulsion layer, the photographic record of the photon is displaced laterally by a distance x.
  • thickness displacement of the silver halide grains is further increased by the presence of additional materials that either (1) increase the thicknesses of the emulsion layers themselves--as where dye-image-providing materials, for example, are incorporated in the emulsion layers or (2) form additional layers separating the silver halide emulsion layers, thereby increasing their thickness displacement--as where separate scavenger and dye-image-providing material layers separate adjacent emulsion layers.
  • the high aspect ratio tabular grain silver halide emulsions employed in the multicolor photographic elements of the present invention are advantageous because of their reduced high angle light scattering as compared to nontabular and lower aspect ratio tabular grain emulsions.
  • the art has long recognized that image sharpness decreases with increasing thickness of one or more silver halide emulsion layers.
  • the lateral component of light scattering x and 2x
  • the lateral displacement of scattered light remains small and image sharpness remains high.
  • a sample of an emulsion 1 according to the present invention is coated on a transparent (specularly transmissive) support 3 at a silver coverage of 1.08 g/m 2 .
  • the emulsion and support are preferably immersed in a liquid having a substantially matched refractive index to minimize Fresnel reflections at the surfaces of the support and the emulsion.
  • the emulsion coating is exposed perpendicular to the support plane by a collimated light source 5.
  • the high aspect ratio tabular grain emulsions of this invention exhibit less high-angle scattering. Since it is high-angle scattering of light that contributes disproportionately to reduction in image sharpness, it follows that the high aspect ratio tabular grain emulsions of the present invention are in each instance capable of producing sharper images.
  • the term "collection angle” is the value of the angle 8 at which half of the light striking the detection surface lies within an area subtended by a cone formed by rotation of line AC about the polar axis at the angle 6 while half of the light strikes the detection surface within the remaining area.
  • the thinness of tabular grains as well as their orientation when coated permits the high aspect ratio tabular grain emulsion layers of this invention to be substantially thinner than conventional emulsion coatings, which can also contribute to sharpness.
  • the tabular silver iodide grains can be even thinner than tabular grains of other silver halide compositions and be coated at lower silver coverages while still exhibiting efficient blue absorption.
  • high aspect ratio tabular grain silver iodide elements often are capable of permitting significant improvements in sharpness in the multicolor elements of this invention.
  • the high aspect ratio tabular grain emulsion layers exhibit a minimum average grain diameter of at least 1.0 pm, most preferably at least 2 pm. Both improved speed and sharpness are attainable as average grain diameters are increased. While maximum useful average grain diameters will vary with the graininess that can be tolerated for a specific imaging application, the maximum average grain diameters of high aspect ratio tabular grain emulsions according to the present invention are in all instances less than 30 pm, preferably less than 15 ⁇ m, and optimally no greater than 10 ⁇ m.
  • the emulsion layer of the multicolor photographic element lying nearest the exposing radiation source contains grains having an average diameter in the range of from 0.2 to 0.6 ⁇ m, as is typical of many nontabular emulsions, it will exhibit maximum scattering of light passing through it to reach the underlying emulsion layers.
  • the tabular grains can scatter the light passing through to one or more underlying emulsion layers to an even greater degree than a conventional emulsion.
  • this particular choice of emulsions and layer arrangement results in the sharpness of the emulsion layer or layers underlying the high aspect ratio tabular grain emulsion layer being significantly degraded to an extent greater than would be the case if no high aspect ratio tabular grain emulsions were present in the layer order arrangement.
  • the tabular grain emulsion layer be positioned to receive light that is free of significant scattering (preferably positioned to receive substantially specularly transmitted light).
  • improvements in sharpness in emulsion layers underlying tabular grain emulsion layers are best realized only when the tabular grain emulsion layer does not itself underlie a turbid layer.
  • a high aspect ratio tabular grain green recording emulsion layer overlies a red recording emulsion layer and underlies a Lippmann emulsion layer and/or a high aspect ratio tabular grain blue recording emulsion layer according to this invention
  • the sharpness of the red recording emulsion layer will be improved by the presence of the overlying tabular grain emulsion layer or layers.
  • the collection angle of the layer or layers overlying the high aspect ratio tabular grain green recording emulsion layer is less than about 10°, an improvement in the sharpness of the red recording emulsion layer can be realized. It is, of course, immaterial whether the red recording emulsion layer is itself a high aspect ratio tabular grain emulsion layer insofar as the effect of the overlying layers on its sharpness is concerned.
  • each emulsion layer which lies nearer the exposing radiation source than another image recording emulsion layer is a high aspect ratio tabular grain emulsion layer.
  • Silver bromide and silver bromoiodide emulsions possess sufficient native sensitivity to the blue portion of the spectrum to record blue radiation without blue spectral sensitization. When these emulsions are employed to record green and/or red (minus blue) light exposures, they are correspondingly spectrally sensitized.
  • the native sensitivity of silver bromide and silver bromoiodide in emulsions intended to record blue light is advantageous.
  • the native blue sensitivity is an inconvenience, since response to both blue and green light or both blue and red light in the emulsion layers will falsify the hue of the multicolor image sought to be reproduced.
  • the color falsification can be analyzed as two distinct concerns.
  • the first concern is the difference between the blue speed of the green or red recording emulsion layer and its green or red speed.
  • the second concern is the difference between the blue speed of each blue recording emulsion layer and the blue speed of the corresponding green or red recording emulsion layer.
  • the aim is to achieve a difference of about an order of magnitude between the blue speed of each blue recording emulsion layer and the blue speed of the corresponding green or red recording emulsion layer.
  • Still another disadvantage associated with separating the blue emulsion layer or layers of a photographic element from the red and green emulsion layers by interposing a yellow filter is that the speed of the blue emulsion layer is decreased. This is because the yellow filter layer absorbs blue light passing through the blue emulsion layer or layers that might otherwise be reflected to enhance exposure.
  • U.K. Patent 1,560,963 which teaches relocating the yellow filter layer
  • U.S. Patent 2,344,084 which teaches using silver chloride and silver chlorobromide emulsions
  • U.S. Patents 2,388,859, and 2,456,954 which teach introducing an order of magnitude difference between the blue and minus blue speeds of the blue and minus blue recording emulsion layers; but each has introduced other significant disadvantages.
  • U.K. Patent 1,560,963 incurs blue light contamination of the minus blue recording emulsions lying above the yellow filter
  • Patent 2,344,084 incurs the reduced speeds and lower speed-granularity relationships of silver chloride and silver chlorobromide emulsions; and U.S. Patents 2,388,859 and 2,456,954 require large grain size differences to obtain an order of magnitude speed difference in the blue and minus blue recording emulsion layers, which requires either increasing granularity or significantly reducing speed.in at least one emulsion layer.
  • locating at least one high aspect ratio tabular grain silver iodide blue recording emulsion layer between the source of exposing radiation and the minus blue recording emulsion layers of the multicolor photographic element protects the minus blue recording emulsion layers from blue light exposure even more efficiently than most conventional yellow filter layers incorporated in multicolor photographic elements.
  • conventional yellow filter layers can be entirely eliminated from multicolor photographic elements according to the present invention while avoiding color falsification by the minus blue recording emulsion layers.
  • the use of a blue recording high aspect ratio tabular grain silver ioidide emulsion in the multicolor photographic elements according to the present invention both avoids color falsification by blue light exposure of the minus blue recording emulsion layers and allows additional improvements in sharpness and speed-granularity relationships to be realized.
  • Each faster or slower color-forming layer unit can differ in photographic speed from another color-forming layer unit which records light exposure in the same third of the spectrum as a result of its position in the Layer Order Arrangement, its inherent speed properties, or a combination of both.
  • the location of the support is not shown. Following customary practice, the support will in most instances be positioned farthest from the source of exposing radiation--that is, beneath the layers as shown. If the support is colorless and specularly transmissive--i.e., transparent, it can be located between the exposure source and the indicated layers. Stated more generally, the support can be located between the exposure source and any color-forming layer unit intended to record light to which the support is transparent.
  • the blue recording color-forming layer unit is positioned to receive exposing radiation first.
  • This color-forming layer unit contains one or more silver halide emulsions comprised of high average aspect ratio silver iodide grains. This emulsion very efficiently absorbs the blue light and substantially none of the minus blue light incident upon it.
  • the tabular silver iodide grains can be relied upon to absorb most or substantially all of the blue light of a wavelength less than 430 nm even in the absence of a blue spectral sensitizing dye.
  • blue light absorption by the color-forming layer unit can be extended to longer blue wavelengths. If desired to obtain a more nearly balanced blue absorption over portions of the blue spectrum longer and shorter than 430 nm in wavelength, the thickness of the tabular silver iodide grains can be reduced below about 0.1 pm down to the minimum grain thicknesses attainable.
  • the blue-recording color-forming layer unit can be thinner than conventional emulsion layers or even high aspect ratio tabular grain emulsion layers of differing silver halide content, such as silver bromide or silver bromoiodide emulsion layers.
  • the fact that the blue recording color-forming layer unit contains high aspect ratio tabular grains allows a sharper image to be produced in this color-forming layer unit. Further, the fact that the blue recording color-forming layer unit is positioned to receive imaging radiation that is substantially specular, contributes to improving the sharpness of the minus blue recording color forming layer units.
  • the green and red-recording color-forming layer units can contain emulsions of any silver halide composition, including silver bromide and/or silver bromoiodide emulsions, without exhibiting color falsification.
  • the green and red recording color-forming layer units can be of any conventional silver halide composition (including silver iodide) or grain configuration (including high aspect ratio tabular grain configuration).
  • I iodide ion can, but need not be released by the blue recording color-forming layer unit.
  • the tabular silver iodide grains are sensitized by epitaxial deposition of a silver halide other than iodide, such as silver chloride, it is possible to develop the silver chloride selectively, as described above. In this case few, if any, iodide ions are released by development.
  • the tabular silver iodide grains are developed, at least to some extent, iodide ions can be allowed to migrate to the adjacent color-forming unit to produce useful interimage effects.
  • the green and red recording color-forming layer units are comprised of high average aspect ratio tabular silver halide grains which permit most of the blue - light striking the grains to pass through unabsorbed. This can be permitted by the composition of the grains (i.e., the absence of or low concentrations of iodide) and/or diminished thicknesses of the grains.
  • the blue recording color-forming layer unit is coated on a reflective support, such as a white support. It is well appreciated that both initially incident radiation and initially unabsorbed reflected radiation contribute to exposure of emulsion layers coated on white reflective supports.
  • the tabular silver iodide grains absorb blue light initially incident upon them and, if any blue light is not initially absorbed, these grains also absorb blue light reflected by the support. Thus the green and red recording color-forming layer units are protected from blue light exposure by reflection.
  • the use of the silver iodide tabular grains in the blue recording color-forming layer unit significantly reduces the blue exposure of the minus blue recording emulsion layers even though the blue recording color-forming layer unit is not interposed between the radiation source and the minus blue recording color-forming layer units.
  • each of the color-forming layer units in Layer Order Arrangement II are comprised of high average aspect ratio silver halide. grains, very high levels of sharpness are possible. Further, Layer Order Arrangement II offers a significant advantage in that the green recording color-forming layer unit is positioned nearest the source of exposing radiation. This allows a sharper image to be produced in the green color-forming layer unit as well as permitting its speed-granularity relationship to be improved. Since the human eye is more sensitive to the green recording color-forming layer unit image than the images produced in the remaining color-forming layer units, the advantages realized in the green recording color-forming layer unit are highly advantageous in achieving the best overall multicolor photographic image.
  • Layer Order Arrangment III differs from Layer Order Arrangement I in that the green and red recording color-forming layer units both contain high aspect ratio tabular grain silver iodide emulsions. In view of the capability of producing extremely thin tabular silver iodide grains, this allows the color-forming layer units to be substantially reduced in thickness. This in turn allows sharper photographic images to be produced, particularly in the red recording color-forming layer unit, although where a white reflective support is employed, significant improvements in sharpness may be realized in each of the color-forming layer units. Although the minus blue color-forming layer units are highly efficient in recording blue light, they are protected from blue light exposure by the overlying tabular silver iodide grains in the blue recording color-forming layer unit.
  • Layer Order Arrangement IV differs from Layer Order Arrangement I by the addition of an additional blue recording color forming layer unit containing a fast high aspect ratio tabular grain silver halide emulsion the halide of which need not be silver iodide.
  • the additional blue color-forming layer unit avoids scattering incident radiation which would degrade the sharpness of imaging records in underlying emulsion layers.
  • the fast blue-recording layer unit is relied upon to achieve a blue speed which matches the green and red speeds of the underlying emulsion layers.
  • the high aspect ratio tabular silver iodide emulsion can be used to extend the exposure latitude of the fast blue recording color-forming layer unit while at the same time more efficiently protecting the underlying color-forming layer units from blue light exposure. Since the two blue recording color-forming layer units are adjacent each other, there is no need to provide an interlayer for oxidized developing agent scavenger. However, since the blue recording color-forming layer units are of differing halide composition, the inclusion of an iodide scavenger in an interlayer between the color-forming layer units is shown, although neither the use of an interlayer or an iodide scavenger is essential.
  • the iodide scavenger can be incorporated in either or both blue recording color-forming layer units, but is preferably incorporated in the one containing tabular silver iodide grains. Iodide scavenger can also be present in the interlayer separating the tabular silver iodide grain containing blue recording color-forming layer unit from the green recording color-forming layer unit.
  • Layer Order Arrangement V illustrates the application of the invention to a multicolor photographic element containing multiple blue, green, and red color-forming layer units.
  • Incident radiation initially strikes a green recording color-forming layer unit comprised of a substantially optimally sensitized high aspect ratio tabular grain silver halide emulsion, preferably a silver bromoiodide emulsion.
  • the light then passes through to an underlying red recording color-forming layer unit, which can be identical to the green recording color-forming layer unit above, except that the silver halide emulsion is sensitized to red light.
  • a fast blue recording color-forming layer unit After passing through the upper two minus blue recording color-forming layer units, light is received by a fast blue recording color-forming layer unit.
  • the fast blue recording color-forming layer unit can contain one or more silver halide emulsion layers of any conventional type, this color-forming layer unit is preferably identical to the fast blue color-forming layer unit described in connection with Layer Order Arrangement IV.
  • a second blue recording color-forming layer unit is shown containing a high aspect ratio tabular grain silver iodide emulsion.
  • An iodide scavenger is also shown in this color-forming layer unit. It is appreciated that the blue recording silver halide emulsions can be present, if desired, in the same color-forming layer unit, either blended or, preferably, coated as separate layers.
  • the silver halide emulsions in these two fast minus blue recording color-forming layer units can be from among any green or red sensitized emulsions heretofore described.
  • the green and red sensitized silver halide emulsions are identical to those of the outermost two color-forming layer units. That is, these minus blue recording color-forming layer units preferably also contain substantially optimally sensitized high aspect ratio tabular grain emulsions, most preferably silver bromoiodide emulsions.
  • the two minus blue recording color-forming layer units farthest from the exposing radiation source are labeled slow color-forming green and red recording color-forming layer units. Their function is to extend the exposure latitude of the photographic element and to contribute additional density for achieving maximum dye densities in the case of a negative-working photographic element.
  • the emulsions employed can be of any conventional type. They can be identical to the silver halide emulsions employed in the other minus blue-recording color-forming layer units, relying on their less favored layer order arrangement to reduce their effective speed. Speed-granularity advantages are realized by coating faster and slower emulsions in separate layers as opposed to blending the emulsions.
  • the multicolor photographic elements of the present invention can, if desired, be applied to image transfer applications.
  • a multicolor photographic elements can form a part of a multicolor image transfer film unit.
  • the photographic elements When employed in image transfer film units they incorporate dye image providing materials which undergo an alteration of mobility as a function of silver halide development.
  • An image dye receiver can form a part of the image transfer film unit or be separate therefrom.
  • Useful image transfer film unit features are disclosed in Research Disclosure, Item 17643, cited above, Paragraph XXIII, and Research Disclosure, Vol. 152, November 1976, Item 15162.
  • Example Emulsions 1 through 4 relate to silver halide emulsions in which the tabular silver iodide grains are of a face centered cubic crystal structure.
  • Example Emulsion 1 Tabular Grain Silver Iodide Emulsion
  • the emulsion was centrifuged, resuspended in distilled water, centrifuged, resuspended in 1.0 liters of a 3 percent gelatin solution and adjusted to pAg 7.2 measured at 40°C.
  • the resultant tabular grain silver iodide emulsion had an average grain diameter of 0.84 ⁇ m, an average grain thickness of 0.066pm, an aspect ratio of 12.7:1, and greater than 80 percent of the grains were tabular based on projected area.
  • x-ray powder diffraction analysis greater than 90 percent of the silver iodide was estimated to be present in the ⁇ phase. See Figure 1 for a carbon replica electron micrograph of a sample of the emulsion.
  • Emulsion 3 was prepared similarly to the epitaxial AgCl tabular grain AgI emulsion of Example 2 with the exception that 15 seconds after the start of the silver salt and halide salt solutions 1.44 mg of an iridium compound/Ag mole was added to the reaction vessel.
  • Example Emulsions 1, 2 and 3 were each coated on a polyester film support at 1.73 g silver/m 2 and 3.58 g gelatin/m 2 .
  • the coatings were overcoated with 0.54 g gelatin/m 2 and contained 1.0 percent bis(vinylsulfonylmethyl)ether hardener based on total gelatin content.
  • the coatings were exposed for 1/2 second to a 600W 2850°K tungsten light source through a 0-6.0 density step tablet (0.30 steps) and processed for 6 minutes at 20°C in a total (surface + internal) developer of the type described by U.S. Patent 3,826,654.
  • Sensitometric results reveal that for the tabular grain AgI host emulsion (Emulsion 1) no discernible image was obtained. However, for the epitaxial AgCl (10 mole percent)/tabular grain AgI emulsion (Emulsion 2), a significant negative image was obtained with a D-min of 0.17, a D-max of 1.40, and a contrast of 1.7. For the iridium sensitized epitaxial AgCl (10 mole percent)/tabular grain AgI emulsion (Emulsion 3) a negative image was obtained with a D-min of 0.19, a D-max of 1.40, a contrast of 1.2, and approximately 0.5 log E faster in threshold speed than Emulsion 2.
  • This emulsion was prepared similar to Example Emulsion 1 except that it contained 0.011 molar K 2 HPO 4 in the precipitation vessel and 0.023 molar K 2 HP0 4 in the 2.5 molar potassium iodide solution.
  • the resultant tabular grain emulsion was found to consist of silver iodide. No phosphorus was detectable using x-ray microanalysis.
  • the AgI tabular grain emulsion had an average grain diameter of 1.65pm compared to 0.84pm found for Example Emulsion 1, an average grain thickness of 0.20pm, an aspect ratio of 8.3:1, and greater than 70 percent of the grains were tabular based on projected area. Greater than 90 percent of the silver iodide was present in the y phase as determined by x-ray powder diffraction analysis.
  • Example Emulsions 5 through 8 relate to silver halide emulsions in which the tabular silver iodide grains are of a hexagonal crystal structure, indicating the silver iodide to be present predominantly in the B phase.
  • the iodide salt solution was added at a rate sufficient to maintain the pI at 1.2 at 80°C throughout the run.
  • the emulsion was cooled to 30°C, washed by the coagulation method of U.S. Patent 2,614,928, and stored at pH 5.8 and pAg 9.5 measured at 40°C.
  • the resultant tabular grain silver iodide emulsion had an average grain diameter of 2.5 um, an average thickness of 0.30 ⁇ m, an average aspect ratio of 8.3:1, and greater than 75 percent of the projected area was provided by tabular grains. See Figure 3 for a photomicrograph of Emulsion 5.
  • Solution C was then added at accelerated flow rates in five intervals of 125 minutes, 150 minutes, 150 minutes, 150 minutes, and 20 minutes each consuming 13.7 percent, 20.8 percent, 25.3 percent, 29.7 percent, and 4.0 percent, respectively, of the total silver used.
  • Solution B was added concurrently throughout at flow rates sufficient to maintain the pI at 1.6 at 90°C.
  • the emulsion was cooled to 30°C, washed by the coagulation method of U.S. Patent 2,614,928, and stored at pH 6.0 and pAg 9.5 measured at 40°C. Approximately 7.6 x 10 -1 mole of silver was used to prepare this emulsion.
  • the resultant tabular grain silver iodide emulsion had an average grain diameter of 7.7pm, an average thickness of 0.35pm, an aspect ratio of 22:1, and greater than 75 percent of the projected area was provided by the tabular grains.
  • a total of 2.03 liters of a 0.98 percent deionized phthalated gelatin aqueous solution containing 444.0 g (0.44 mole) of Emulsion 6 were placed in a precipitation vessel with stirring.
  • the pH was adjusted to approximately 6.2.
  • the pAg was adjusted to approximately 7.6 at 40°C using a 1 x 10- 3 molar potassium bromide solution.
  • a 0.1 molar potassium bromide solution at 40°C and a 0.1 molar silver nitrate solution at 40°C were run concurrently into the precipitation vessel by double-jet addition.
  • the silver salt solution was added for 30 minutes at 14.8 ml/minute while the bromide salt solution was added at a rate sufficient to maintain the pAg at 7.6 at 40°C.
  • Approximately 10 mole percent silver bromide was added to the tabular grain silver iodide host emulsion.
  • the emulsion was cooled to 30°C, washed by the coagulation method of U.S. Patent 2,614,928, and stored at pH 5.8 and pAg 8.2 measured at 40°C.
  • the silver bromide epitaxially deposited was almost exclusively along the edges of the tabular silver iodide host crystals.
  • Example Emulsion 8 Silver Chloride (10 mole percent) Deposition on Tabular Grain AgI Emulsion
  • a total of 1.98 liters of a 1.26 percent deionized phthalated gelatin aqueous solution containing 486.0 g (0.44 mole) of an Emulsion 6 repeat were placed in a precipitation vessel with stirring.
  • the pH was adjusted to approximately 6.0.
  • the pAg was adjusted to approximately 6.9 at 40°C using a 1.0 molar potassium chloride solution.
  • a 9.25 x 10- 2 molar potassium chloride solution at 40°C and a 9.25 x 10- 2 molar silver nitrate solution at 40°C were run concurrently into the precipitation vessel by double-jet addition.
  • the silver salt solution was added for 60 minutes at 8.0 ml/minute while the chloride salt solution was added at a rate such that the pAg changed from 6.9 to 6.7 at 40°C throughout the run.
  • Approximately 10 mole percent silver chloride was added to the tabular grain silver iodide host emulsion.
  • the emulsion was cooled to 30°C, washed by the coagulation method of U.S. Patent 2,614,928, and stored at pH 5.0 and pAg 7.2 measured at 40°C.
  • the silver chloride epitaxially deposited was almost exclusively along the edges of the tabular silver iodide host crystals.
  • Example Emulsions 6, 7, and 8 were separately coated on polyester film support at 1.61 g silver/m 2 and 5.38 g gelatin/m 2.
  • the coating elements also contained 1.61 g yellow coupler a-pivalyl-a[4-(4-hydroxybenzenesulfonyl)-phenoxy]-2-chloro-5-(n-hexadecanesulfonamido)-acetanilide/m 2 , 3.29 g 2-(2-octadecyl)-5-sulfo- hydroquinone, sodium salt/Ag mole and 1.75 g 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene/Ag mole.
  • the coating elements were overcoated with a 0.89 g gelatin/m 2 layer that contained 1.75 percent by weight hardener bis(vinylsulfonylmethyl)ether based on total gelatin content.
  • Emulsion 8 was also spectrally sensitized with 0.25 millimole anhydro-5,5'-dichloro-3,3'-bis(3-sulfopropyl)thiacyanine hydroxide trimethylamine salt/Ag mole and then chemically sensitized with 15 mg gold sulfide/Ag mole for 5 minutes at 55°C and coated as described above.
  • the coatings were exposed for 1/10 second to a 600 watt 3000 0 K tungsten light source through a 0-6.0 density step tablet (0.30 steps) and processed for either 3 or 6 minutes at 37.7°C in a color developer of the type described in The British Journal of Photography Annual, 1979, pages 204-206.
  • Emulsion 6 the tabular grain AgI host emulsion, no discernible image was obtained at either 3 minutes or 6 minutes development time.
  • Emulsion 7 the AgBr deposited on AgI host emulsion, resulted in a significant negative image at 6 minutes development with a D-min of 0.13, a D-max of 0.74, and a contrast of 0.42.
  • Unsensitized Emulsion 8 the AgCl deposited on AgI host emulsion, resulted in a substantial negative image at 3 minutes development with a D-min of 0.13, a D-max of 0.74, and a contrast of 0.80.
  • the chemically and spectrally sensitized Emulsion 8 which had a D-min of 0.13, D-max of 0.80, and contrast of 0.65, was approximately 0.60 log E faster in speed than unsensitized Emulsion 8.
  • Emulsion 9 in the amount of 1048 grams (1.3 mole AgI) prepared above was placed in a precipitation vessel. Next 1.3 liters of distilled water were added and the emulsion was adjusted to pAg 7.0 at 40°C using a 1.0 molar KCl solution. Then a 1.0 molar KC1 solution and a 0.46 molar AgN0 3 solution were added over two hours by double-jet utilizing accelerated flow (2x from start to finish) at controlled pAg 7.0 at 40°C. A total of 10 mole percent silver chloride was precipitated onto the silver iodide host Emulsion 9. Following precipitation the emulsion was cooled to 30°C and washed by the coagulation method of U.S. Patent 2,614,928. See Figure 5 for a photomicrograph of Emulsion 10.
  • a tabular grain AgI emulsion was prepared by a double-jet precipitation technique.
  • the emulsion had an average grain diameter of 6.0 ⁇ m, an average grain thickness of 0.23 ⁇ m, an average aspect ratio of 26:1, and greater than 75 percent of the projected surface area was contributed by the tabular silver iodide grains.
  • Emulsion A was a three-dimensional grain silver iodide with an average grain size of 0.75 ⁇ m and an average grain volume of 0.22( ⁇ m) 3 .
  • Emulsion B was a tabular grain silver bromoiodide (97:3) emulsion with an average grain diameter of 1.8 ⁇ m, an average grain thickness of 0.099pm, an aspect ratio of 18:1, an average projected area of greater than 80%, and an average grain volume of 0.25( ⁇ m) 3 .
  • Emulsion C satisfying the requirements of this invention, was a tabular grain silver iodide emulsion with an average grain diameter of 1.7 ⁇ m, an average grain thickness of 0.095 ⁇ m, an average aspect ratio of 17.9:1, a tabular grain projected area of greater than 50% of the total grain projected area, and an average grain volume of 0.21( ⁇ m) 3 .
  • Each emulsion was coated in the blue layer (Layer 9) at 0.97 g. silver/m 2 and 1.51g. gelatin/m 2 .
  • Layer 9 also contained 2-(2-octadecyl)-5-sulfohydro-quinone, sodium salt at 0.30 g/m 2 and 4-hydroxy-6-methyl-1,3,3a,7-tetraazain- dene at 2.27 g/m 2 .
  • No yellow filter layer was present in the multilayer element.
  • the multilayer element was overcoated with 1.36 g. gelatin/m 2 and hardened with 2.0% bis-(vinylsulfonyl-methyl) ether based on the total gelatin content.
  • a control coating was also prepared with the exception that the silver halide emulsion was omitted from Layer 9. Gelatin was coated at 1.51 g/m 2 in that layer. The remaining layers were the same as described above.
  • Each coating was exposed for 1/10 second to a 600W 5500 0 K tungsten light source through a 0-6.0 density step tablet (0.30 steps) plus Wratten 36 + 38A filter (permitting only 350 to 460 nm wavelength light to be transmitted) and processed for 2 1/2 minutes in a color developer of the type described in the British Journal of Photography Annual, 1979, pages 204-206.
  • Emulsion C had the lowest relative blue speed in the magenta recordayer. This indicated that of the three emulsions of near equivalent grain volumes, the tabular grain silver iodide emulsion absorbed the greatest amount of blue light.
  • the improvement of Emulsion C over Emulsion A demonstrated that blue light absorption by silver iodide occurred due to projected surface area rather than grain volume.

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Cited By (8)

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EP0211437A2 (de) * 1985-08-05 1987-02-25 Fuji Photo Film Co., Ltd. Verfahren zur Behandlung farbphotographischer Silberhalogenidmaterialien
EP0219849A2 (de) * 1985-10-23 1987-04-29 EASTMAN KODAK COMPANY (a New Jersey corporation) Mehrfarbige photographische Elemente
EP0219850A2 (de) * 1985-10-23 1987-04-29 EASTMAN KODAK COMPANY (a New Jersey corporation) Mehrfarbige photographische Elemente (I)
US4748106A (en) * 1985-07-18 1988-05-31 Fuji Photo Film Co., Ltd. Color photographic light-sensitive materials containing specified tabular grains
EP0228914A3 (en) * 1985-12-28 1989-01-25 Konishiroku Photo Industry Co. Ltd. Method of processing lightsensitive silver halide color photographic material
EP0507702A1 (de) * 1991-04-03 1992-10-07 Eastman Kodak Company Photographische Elemente verbesserter Schärfe
US7129032B2 (en) 2003-10-24 2006-10-31 Fuji Photo Film Co., Ltd Black and white photothermographic material and image forming method
CN109743051A (zh) * 2019-03-22 2019-05-10 广东美的制冷设备有限公司 驱动控制电路和家电设备

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JPS6172235A (ja) * 1984-09-14 1986-04-14 Konishiroku Photo Ind Co Ltd ハロゲン化銀カラ−写真感光材料
JPS6172234A (ja) * 1984-09-14 1986-04-14 Konishiroku Photo Ind Co Ltd ハロゲン化銀カラ−写真感光材料
JPH0715571B2 (ja) * 1985-07-19 1995-02-22 富士写真フイルム株式会社 ハロゲン化銀カラ−写真感光材料
JP2655141B2 (ja) * 1985-07-23 1997-09-17 富士写真フイルム株式会社 ハロゲン化銀乳剤の製造方法
JPS62151840A (ja) * 1985-12-26 1987-07-06 Fuji Photo Film Co Ltd 高アスペクト比のヨウ臭化銀乳剤の調製方法
JP2607362B2 (ja) * 1986-01-20 1997-05-07 コニカ株式会社 ハロゲン化銀カラー写真感光材料
JP2619238B2 (ja) * 1986-03-05 1997-06-11 コニカ株式会社 ハロゲン化銀カラー写真感光材料
JP2634059B2 (ja) * 1988-04-08 1997-07-23 富士写真フイルム株式会社 ハロゲン化銀カラー写真感光材料
US5476760A (en) 1994-10-26 1995-12-19 Eastman Kodak Company Photographic emulsions of enhanced sensitivity
US6994952B2 (en) 2002-03-22 2006-02-07 Fuji Photo Film Co., Ltd. Silver halide emulsion and production process thereof
CN102636952A (zh) * 2012-04-19 2012-08-15 蔡新民 一种防止激光光绘菲林变形的制作方法

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FR2295454A1 (fr) * 1974-12-19 1976-07-16 Ciba Geigy Ag Emulsions d'halogenure d'argent utilisees en photographie et leur procede de fabrication
US4184877A (en) * 1976-06-10 1980-01-22 Ciba-Geigy Ag Process for the manufacture of photographic silver halide emulsions containing silver halide crystals of the twinned type
GB2109576A (en) * 1981-11-12 1983-06-02 Eastman Kodak Co High aspect ratio photographic silver bromoiodide emulsions and processes for their preparation

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FR2295454A1 (fr) * 1974-12-19 1976-07-16 Ciba Geigy Ag Emulsions d'halogenure d'argent utilisees en photographie et leur procede de fabrication
US4184877A (en) * 1976-06-10 1980-01-22 Ciba-Geigy Ag Process for the manufacture of photographic silver halide emulsions containing silver halide crystals of the twinned type
GB2109576A (en) * 1981-11-12 1983-06-02 Eastman Kodak Co High aspect ratio photographic silver bromoiodide emulsions and processes for their preparation

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4748106A (en) * 1985-07-18 1988-05-31 Fuji Photo Film Co., Ltd. Color photographic light-sensitive materials containing specified tabular grains
EP0211437A2 (de) * 1985-08-05 1987-02-25 Fuji Photo Film Co., Ltd. Verfahren zur Behandlung farbphotographischer Silberhalogenidmaterialien
EP0211437A3 (en) * 1985-08-05 1989-03-15 Fuji Photo Film Co., Ltd. Process for processing silver halide color photographic materials
EP0219849A2 (de) * 1985-10-23 1987-04-29 EASTMAN KODAK COMPANY (a New Jersey corporation) Mehrfarbige photographische Elemente
EP0219850A2 (de) * 1985-10-23 1987-04-29 EASTMAN KODAK COMPANY (a New Jersey corporation) Mehrfarbige photographische Elemente (I)
EP0219850A3 (en) * 1985-10-23 1989-04-26 Eastman Kodak Company Multicolor photographic elements (i)
EP0219849A3 (en) * 1985-10-23 1989-04-26 Eastman Kodak Company Multicolor photographic elements (ii)
EP0228914A3 (en) * 1985-12-28 1989-01-25 Konishiroku Photo Industry Co. Ltd. Method of processing lightsensitive silver halide color photographic material
US5032494A (en) * 1985-12-28 1991-07-16 Konishiroku Photo Industry Co., Ltd. Method of processing light-sensitive silver halide color photographic material having three mole % silver iodine core/shell or tabular halide grains
EP0507702A1 (de) * 1991-04-03 1992-10-07 Eastman Kodak Company Photographische Elemente verbesserter Schärfe
US7129032B2 (en) 2003-10-24 2006-10-31 Fuji Photo Film Co., Ltd Black and white photothermographic material and image forming method
CN109743051A (zh) * 2019-03-22 2019-05-10 广东美的制冷设备有限公司 驱动控制电路和家电设备

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EP0111919B1 (de) 1987-04-29
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CA1210626A (en) 1986-09-02
JPS59119350A (ja) 1984-07-10

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