Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/0051—Tabular grain emulsions

Definitions

• This invention relates to a silver halide photographic material for use in silver halide photographic materials. More particularly, this invention relates to a silver halide photographic emulsion for use in silver halide photographic materials that are improved in sensitivity, graininess and keeping quality.
• tabular silver halide grains Compared to silver halide grains as crystals of "regular" shapes such as octahedra, tetradecahedra and hexahedra, tabular silver halide grains have a large surface area given the same grain volume and, hence, more sensitizing dyes can be adsorbed on the surfaces of tabular silver halide grains to provide even higher sensitivity.
• Unexamined Published Japanese Patent Application No. 92942/1988 proposes the technique of providing a core of the higher silver iodide content in the interior of tabular silver halide grains;
• Unexamined Published Japanese Patent Application No. 151618/1988 proposes the technique of using hexagonal tabular silver halide grains;
• Unexamined Published Japanese Patent Application No. 163451/1988 proposes the technique of using tabular silver halide grains of such a shape that the ratio of grain thickness to the longest distance between twinned faces is at least 5.
• Unexamined Published Japanese Patent Application No. 106746/1988 describes tabular silver halide grains having a layer structure that extends substantially parallel to two opposing principal planes
• Unexamined Published Japanese Patent Application No. 279237/1989 describes the technique of using tabular silver halide grains that have a layer structure that is bound by planes substantially parallel to two opposing principal planes and whose average silver iodide content of the outermost layer is at least 1 mol% higher than the average silver iodide content of the silver halide grains taken as a whole.
• Unexamined Published Japanese Patent Applciation No. 183644/1989 discloses the technique of using tabular silver halide grains that are completely uniform in the distribution of silver iodide in silver halide grains containing silver iodide.
• the present invention has been accomplished under these circumstances and has as an object providing a silver halide photographic emulsion that yields silver halide photographic materials having high sensitivity, good graininess and satisfactory keeping quality.
• a light-sensitive silver halide photographic emulsion comprising: tabular silver halide grains having a total projected area of at least 50 % of all the grains in said emulsion, an average silver iodide content of said tabular silver halide grains being at least 5 mol%, each said tabular silver halide grains having an internal phase and an outermost layer, said internal phase having an silver iodide content of at least 18 mol%, said outermost layer having an silver iodide content of not more than 0.4 mol%, wherein a sectional plane cutting each said silver halide grain in a direction that passes through the center of said tabular silver halide grain and being perpendicular to two parallel major faces satisfies the following relation: 90/100 ⁇ a/b ⁇ 100/90 where a is an average silver iodide content of a region that are defined by a distance over 9d/20 as measured from the center of said tabular silver halide grain
• tabular silver halide grains as used herein means those grains which have two opposing parallel major faces.
• the aspect ratio, or the diameter to thickness ratio, of tabular silver halide grains to be used in the present invention is preferably from 1 to less than 5 on average, more preferably from 1.1 to less than 4.5, and most preferably from 1.2 to less than 4.
• the average value of the aspect ratio can be obtained by averaging the diameter to thickness ratios of all tabular silver halide grains present.
• the diameter of a tabular silver halide grain is expressed in terms of the diameter of an equivalent circle of the projected area of that grain (i.e., the diameter of a circle having the same projected area as that grain); preferably, such diameter is 0.1 - 5.0 ⁇ m, more preferably 0.2 - 4.0 ⁇ m, and most preferably 0.3 - 3.0 ⁇ m.
• the silver halide photographic emulsion of the present invention is such that when it is coated in a single layer with care being taken to insure that the silver halide grains contained in said emulsion will not overlap one another, at least 50%, preferably at least 60%, more preferably at least 70%, of the total projected area of all silver halide grains in the emulsion is assumed by tabular silver halide grains.
• twins are classified crystallographically as twins.
• a "twin” is a silver halide crystal having one or more twinned faces in one grain; morphological classification of twins is described in detail by E.Klein and E.Moisar in Photogr. Korresp., 99 , 99 and ibid., 100 , 57.
• the tabular silver halide grains to be contained in the silver halide photographic emulsion of the present invention are preferably monodispersed. Grains are called "monodispersed” if their monodispersity as defined by the following formula is less than 20%.
• the monodispersity of the tabular silver halide grains is less than 18%, more preferably less than 15%.
• the tabular silver halide grains to be contained in the silver halide photographic emulsion of the present invention are preferably comprised of the major faces in the shape of hexagon assume at least 50%, more preferably at least 60%, most preferably at least 70%, in number of the tabular silver halide grains present.
• a "tabular silver halide grain comprised of the major faces in the shape of hexagon” as used in the present invention has two parallel twinned faces.
• a tabular silver halide grain may be said “to be comprised of the major faces in the shape of hexagon” if the ratio of the longest side to the shortest side of the six sides of the grain, as viewed in a direction perpendicular to the parallel major faces, is preferably not greater than 2, more preferably not greater than 1.8, and most preferably not greater than 1.5.
• the average diameter of the tabular silver halide grains to be used in the present invention can be measured on an electron micrograph of the silver halide emulsion of the present invention. With an electron micrograph enlarged by a magnification of 1 ⁇ 104 - 5 ⁇ 104, the projected areas of hexagonal and triangular silver halide grains are measured and the average diameter of equivalent circles is calculated.
• the tabular silver halide grains contained in the silver halide photographic emulsion of the present invention have an average silver iodide content of at least 5 mol%, more preferably at least 5.5 mol%, and most preferably at least 6 mol%.
• the average silver iodide content can be measured by an EPMA method which is well known in the art.
• the tabular silver halide grains contained in the silver halide photographic emulsion of the present invention have a high silver iodide phase in the interior of each grain, with the AgI content of that phase being preferably at least 18 mol%, more preferably at least 20 mol%, and most preferably at least 25 mol%.
• the interior of grains means the area of each silver halide grain that is inward of a diameter corresponding to 50% of the volume of that grain.
• the silver iodide content of the interior of grains to be used in the present invention can be measured by a method of X-ray microanalysis according to the following procedure: silver halide grains to be examined are dispersed in an observation grid which has an energy-dispersive X-ray analyzer mounted on an electron microscope; under cooling with liquid nitrogen, the magnification is set in such a way that one grain is located within the view field of CRT; the intensities of AgL ⁇ and IL ⁇ rays are integrated for a predetermined time; the silver iodide content of a particular grain can be computed on the basis of the IL ⁇ /AgL ⁇ intensity ratio using a preliminarily constructed calibration curve.
• the tabular silver halide grains to be contained in the silver halide photographic emulsion of the present invention have an average silver iodide content of no higher than 0.4 mol%, preferably no higher than 0.3 mol%, more preferably no higher than 0.2 mol%, in the outermost layer.
• the average silver iodide content in the outermost layer of the tabular silver halide grains to be contained in the silver halide photographic emulsion of the present invention can be measured by X-ray photoelectron spectroscopy (XPS).
• the tabular silver halide grains contained in the silver halide photographic emulsion of the present invention are such that a sectional plane cutting each of said silver halide grains in a direction that passes through its center and which is prependicular to two parallel major faces satisfies the relation: 90/100 ⁇ a/b ⁇ 100/90, preferably 92/100 ⁇ a/b ⁇ 100/92, more preferably 95/100 ⁇ a/b ⁇ 100/95, where a is the average silver iodide content of regions that are defined by a distance of at least 9d/20 as measured from the center of said silver halide grains in a direction that is perpendicular to the two parallel major faces (where d is the distance between the two parallel major faces in association with the sectional plane), and b is the average silver iodide content of regions that are defined by a distance of at least 9l/20 as measured from the center of said silver halide grains in a direction that is parallel to the two parallel major faces (where
• the proportion of tabular silver halide grains that satisfy the relation 90/100 ⁇ a/b ⁇ 100/90 is preferably at least 50%, more preferably at least 60%, and most preferably at least 70%, in number of all the tabular silver halide grains contained in the silver halide photographic emulsion of interest.
• d or the distance between the two parallel major faces in association with a sectional plane through each grain, and l , or the distance between two opposing surfaces of a grain as measured in a direction that passes through the center of said silver halide grains and which is parallel to the two parallel major faces in association with the sectional plane, can be determined by the following process: the gelatin of the silver halide photographic emulsion of the present invention is decomposed with a protease; thereafter, the tabular silver halide grains in said emulsion are embedded in a methacrylic resin, which is then cut with a diamond cutter to prepare a specimen 800 ⁇ thick; the specimen is examined under a transmission electron microscope and a picture in the field of view is taken; the distances d and l are measured on the picture.
• a , or the average silver iodide content of regions that are defined by a distance of at least 9d/20 as measured from the center of said silver halide grains in a direction that is perpendicular to the two parallel major faces and b , or the average silver iodide content of regions that are defined by a distance of at least 9 /20 as measured from the center of said silver halide grains in a direction that is parallel to the two parallel major faces can each be determined on the same specimen as used in the aforementioned examination under a transmission electron microscopy by averaging the silver iodide contents as measured at two sites of a grain that are positioned in point symmetry with respect to the center of that grain by means of point analysis using the EPMA method which is well known in the art.
• the silver halide photographic emulsion of the present invention can generally be produced by a process in which a silver halide emulsion that is prepared by the method described in Japanese Patent Application No. 408178/1990 is used as a seed from which growth is effected at a pH of no higher than 7.5 using an aqueous solution of ammoniacal silver nitrate, which process is characterized in that growth until the end of the formation of a high silver iodide phase is effected in a pAg region of no more than 8.5 and growth subsequent to the formation of that high silver iodide phase is effected in a pAg region of at least 9.2.
• the silver halide grains to be used in the present invention are composed of silver iodobromide or silver iodochlorobromide. They may be of a surface latent image type or an internal latent image type.
• the silver halide photographic emulsion of the present invention can preferably be used in silver halide color photographic materials.
• couplers can be used when composing a color photographic material using the silver halide photographic emulsion of the present invention and specific examples of the couplers that can be used are described in two of the three issues of Research Disclosure. Relevant portions are cited below from the respective RDs.
• the additives to be used when composing a color photogaphic material using the silver halide photographic emulsion of the present invention can be incorporated by various methods such as the method of dispersion described in RD 308119 under XIV.
• a color photographic material using the silver halide photographic emulsion of the present invention may be provided with a filter layer, an intermediate layer and other auxiliary layers as described in RD 308119 under VII-K.
• a color photographic material using the silver halide photographic emulsion of the present invention may adopt various layer arrangements including a conventional layer order, an inverse layer order and a unit structure, as described in RD 308119 under VII-K.
• the silver halide photographic emulsion of the present invention can preferably be applied to various color photographic materials as typified by color negative films for general use or for motion pictures, color reversal films for slides or TV, color papers, color positive films and color reversal papers.
• the color photographic material using the silver halide photographic emulsion of the present invention can be processed by conventional methods as described in RD l7643 on pages 28 - 29, RD 18716 on page 615, and RD 308119 under XIX.
• a comparative emulsion containing core/shell structured) octahedral silver iodobromide grains (average grain size: 1.1 ⁇ m; AgI content: 8 mol%) was prepared by the method described in Unexamined Published Japanese Patent Applciation No. 138538/1985.
• 2.254 L of an aqueous solution containing 536 g of silver nitrate and 2.254 L of an aqueous solution containing 290 g of potassium bromide and 120 g of potassium iodide were added at equal flow rates by a double-jet method with pAg being controlled at 8.9.
• 5.847 L of an aqueous solution containing 1490 g of silver nitrate and 5.847 L of an aqueous solution containing 1044 g of potassium bromide were added at equal flow rates by a double-jet method with pAg being controlled at 9.2, whereupon tabular silver halide grains were precipitated.
• 1.753 L of an aqueous solution containing 536 g of silver nitrate and 1.753 L of an aqueous solution containing 290 g of potassium bromide and 120 g of potassium iodide were added at equal flow rates by a double-jet method with pAg being controlled at 8.0.
• 3.508 L of an aqueous solution containing 1490 g of silver nitrate and 3.508 L of an aqueous solution containing 1044 g of potassium bromide were added at equal flow rates by a double-jet method with pAg being controlled at 8.6, whereupon tabular silver halide grains were precipitated.
• a monodispersed spherical seed emulsion (T-1) was prepared by the following method with reference being made to the disclosure in Japanese Patent Application No. 408178/1990.
• Solution A Ossein gelatin 80.0 g Potassium bromide 39.0 g Potassium iodide 11.7 g Water to make 8 L Solution B Silver nitrate 1.2 kg Water to make 1.6 L Solution C Ossein gelatin 32.2 g Potassium bromide 840 g Water to make 1.6 L Solution D
• solutions B and C were added by a double-jet method over 11 min to form nuclei.
• the pBr of the mixture was held at 1.09 - 1.70.
• the temperature of the mixture was lowered to 30°C over 12 min, followed by ripening for 18 min.
• solution D was added over 1 min, followed by ripening for 5 min.
• the KBr concentration was held at 0.07 mol/L and the ammonia concentration was held at 0.63 mol/L.
• pH adjustment to 6.0 the mixture was immediately desalted and washed with water. Examination of the particles in the seed emulsion under an electron microscope showed that it was a monodispersed spherical emulsion having an average grain size of 0.30 ⁇ m with the spread of distribution being 18%.
• silver halide emulsions of the present invention Em-5, Em-6, Em-7, and Em-8, were prepared in the following manner.
• Fine grained emulsion composed of 3 wt% ossein gelatin and silver iodide grains (average particle size, 0.04 ⁇ m)
• MC-10 was prepared by the following method: 2,000 ml each of aqueous solutions containing 7.06 moles of silver nitrate and 7.06 moles of potassium iodide were added over 10 min to 5,000 ml of a 6.0 wt% gelatin solution containing 0.06 mole of potassium iodide; during the formation of fine grains, the pH was adjusted to 2.0 with nitric acid and the temprerature of the mixture was held at 30°C. After the formation of grains, the mixture was adjusted to a pH of 6.0 with an aqueous solution of sodium carbonate.
• Fine grained emulsion that was composed of 3 wt% ossein gelatin and silver bromide grains (average particle size, 0.04 ⁇ m) and which was prepared by the same method as that for preparing MC-10.
• Seed emulsion (T-1) in an amount equivalent to 0.286 mole was added to the solution G-10 in the reaction vessel as it was stirred well with the temperature, pAg and pH being held at 70°C, 8.3 and 7.2, respectively.
• H-10, S-10 and MC-10 were charged into the reaction vessel at an accelerated speed by a triple-jet method over 140 min at the flow rates necessary to produce the silver halide composition shown in Talbe 1, whereby silver halide grains were grown until the silver addition reached 78%.
• MC-20 was added over 10 min, followed by ripening for 11 min so that silver halide grains would grow until the silver addition reached 100%.
• the pH and pAg were controlled to the values shown in Table 1 by feeding an aqueous solution of potassium bromide and an aqueous solution of acetic acid into the reaction vessel.
• a silver halide emulsion of the present invention, Em-6 was prepared using the seed emulsion (T-1) and the five solutions, G-10, H-10, S-10, MC-10 and MC-20, which were used in preparing Em-5.
• Seed emulsion (T-1) in an amount equivalent to 0.286 mole was added to the solution G-10 in the reaction vessel as it was stirred well with the temperature, pAg and pH being held at 70°C, 8.0 and 7.0, respectively.
• H-10, S-10 and MC-10 were charged into the reaction vessel at an accelerated speed by a triple-jet method over 170 min at the flow rates necessary to produce the silver halide composition shown in Table 2, whereby silver halide grains were grown until the silver addition reached 78%.
• MC-20 was added over 10 min, followed by ripening for 10 min so that silver halide grains would grow until the silver addition reached 100%.
• the pH and pAg were controlled to the values shown in Table 2 by feeding an aqueous solution of potassium bromide and an aqueous solution of acetic acid into the reaction vessel.
• a silver halide emulsion of the present invention, Em-7 was prepared using the seed emulsion (T-1) and the five solutions, G-10, H-10, S-10, MC-10 and MC-20, which were used in preparing Em-5.
• Seed emulsion (T-1) in an amount equivalent to 0.286 mole was added to the solution G-10 in the reaction vessel as it was stirred well with the temperature, pAg and pH being held at 70°C, 8.1 and 7.2, respectively.
• H-10, S-10 and MC-10 were charged into the reation vessel at an accelerated speed by a triple-jet method over 150 min at the flow rates necessary to produce the silver halide composition shown in Talbe 3, whereby silver halide grains were grown until the silver addition reached 78%.
• MC-20 was added over 10 min, followed by ripening for 10 min so that silver halide grains would grow until the silver addition reached 100%.
• the pH and pAg were controlled to the values shown in Table 3 by feeding an aqueous solution of potassium bromide and an aqueous solution of acetic acid into the reaction vessel.
• a silver halide emulsion of the present invention, Em-8 was prepared using the seed emulsion (T-1) and the five solutions, G-10, H-10, S-10, MC-10 and MC-20, which were used in preparing Em-5.
• Seed emulsion (T-1) in an amount equivalent to 0.286 mole was added to the solution G-10 in the reaction vessel as it was stirred well with the temperature, pAg and pH being held at 70°C, 8.4 and 7.0, respectively.
• H-10, S-10 and MC-10 were charged into the reaction vessel at an accelerated speed by a triple-jet method over 125 min at the flow rates necessary to produce the silver halide composition shown in Table 4, whereby silver halide grains were grown until the silver addition reached 78%.
• MC-20 was added over 10 min, followed by ripening for 10 min so that silver halide grains would grow until the silver addition reached 100%.
• the pH and pAg were controlled to the values shown in Table 4 by feeding an aqueous solution of potassium bromide and an aqueous solution of acetic acid into the reaction vessel.
• the thus prepared silver halide emulsions Em-1 to Em-8 were examined under an electron microscope to investigate various parameters.
• the average AgI content of each emulsion was measured by EPMA; the AgI content of the interior of silver halide grains was measured by X-ray microanalysis; the average AgI content of silver halide grains in the outermost layer was measured by XPS.
• point analysis was conducted by EPMA to determine a/b for each emulsion. The results of the microscopic examination and the various measurements are shown in Table 5.
• Silver halide emulsions Em-1 to Em-8 were subjected to optimal chemical sensitization.
• the sensitized emulsions were used in accordance with the formula indicated below, in which each emulsion is designated as Emulsion-A.
• Layers having the compositions described below were formed successively on triacetyl cellulose film bases, with the first layer being positioned the closest to the base, thereby preparing eight samples (Nos. 11 - 18) of multilayered color photographic material.
• the amounts of addition of various ingredients are expressed in grams per square meter.
• the amounts of silver halides and colloidal silver are expressed in terms of silver, and the amounts of sensitizing dyes are expressed in moles per mole of silver.
• Twelfth layer Less blue-sensitive layer
• Second protective layer Sixteenth layer: Second protective layer
• coating aid Su-1 dispersion aid Su-2, viscosity modifier, hardeners H-1 and H-2, stabilizer ST-1, anti-foggant AF-1, two kinds of AF-2 having weight average molecular weights of 10,000 and 1,100,000, and antiseptic DI-1.
• the last-mentioned DI-1 was added in an amount of 9.4 mg/m2.
• the “relative sensitivity (S)” is the relative value of the reciprocal of light reception that gives a fog density + 0.1, with the green sensitivity of sample 11 being taken as 100.
• the "RMS" granularity is 1,000 times the standard deviation of the variation in density that occurs when a density equivalent to fog density + 1.0 is scanned with a microdensitometer having a scanning aperture area of 250 ⁇ m2, with the RMS value of sample 11 being taken as 100.
• Table 6 shows in relative values the results of evaluating the sensitivities and RMS granularities of coated samples 11 - 18 using Em-1 to Em-8, respectively.
• Example 1 The same samples of multi-layered color photographic material as prepared in Example 1 were stored under the following two different conditions and, thereafter, the samples were evaluated as in Example 1.
• Condition A stored at 65°C ⁇ 30 % r.h. for 4 days
• Condition B stored at 50°C ⁇ 80 % r.h. for 4 days
• the present invention offers a silver halide photographic emulsion that yields silver halide photographic materials having high sensitivity, good graininess and satisfactory keeping quality.

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• 1991
  • 1991-09-06 JP JP22727591A patent/JPH0566510A/ja active Pending
• 1992
  • 1992-08-27 DE DE1992617146 patent/DE69217146T2/de not_active Expired - Fee Related
  • 1992-08-27 EP EP19920307827 patent/EP0531052B1/de not_active Expired - Lifetime

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