JPH10293376A - Silver halide emulsion and photosensitive material using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silver halide emulsion having sensitivity enough for use as a blue recording emulsion and using ultra-thin plate type grains of low fogging and high sharpness by applying a reducing and sensitization process internally to plate type silver halide grains at a manufacturing process, and using an emulsion with a specific compound added. SOLUTION: This silver halide emulsion is prepared to contain plate type silver halide grains having a principal plane, a mean silver bromide content ratio equal to or above 70 mol%, a mean circle-equivalent diameter equal to or above 0.7 μm and mean grain thickness less than 0.07 μm, occupying 90% or more of a whole projection area. At the manufacturing process of the emulsion, a reducing and sensitization process is internally applied to the plate type silver halide grains. Also, at least one of compounds selected from an expressed by the formula R-SO2 S-M, R-SO2 S-R1 , R-SO2 S-Lm -SSO2 -R2 is added to the emulsion, where R, R1 and R2 stand for an aliphatic group, an alicyclic formula (compound residue), an aromatic group or a hetero cyclic group, M for a cation, L for a vibalent coupling group and (m) for a numeral of 0 or 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silver halide emulsion and a photographic light-sensitive material using the same, and more particularly to a silver halide emulsion having high sensitivity, low fogging and good sharpness, and a photographic light-sensitive material using the same. About the material.

[0002]

2. Description of the Related Art U.S. Pat. No. 4,439,520 (Ko)
fron et al.) signaled the advent of the current high-performance silver halide photographic era. Kofron et al. Have tabular silver halide grains having a grain diameter of at least 0.6 μm and a grain thickness of less than 0.3 μm (hereinafter also referred to as tabular grains).
Disclose and showed remarkable photographic advantages for chemically and spectrally sensitized tabular grain emulsions having an average aspect ratio of greater than 8 and greater than 50% of total grain projected area. Of the numerous emulsions shown, one or more of these numerical parameters often far exceeded the above requirements. Kofron et al. Disclose chemically and spectrally sensitized emulsions disclosed in one or more of various embodiments in color and black and white photography (including indirect radiography).
Knew it would be useful. Spectral sensitization in all parts of the visible spectrum and at longer wavelengths has been attempted, as well as orthochromatic and panchromatic spectral sensitization for black and white imaging applications. Used a combination of one or more spectral sensitizing dyes with middle chalcogen (eg, sulfur) and / or noble metal (eg, gold) chemical sensitization. However, Kofron et al. Also discloses the usual sensitization, such as the presence of other modifying compounds, for example, metal compounds, as required at the time of deposition, and reduction sensitization.

In 1982, first indirect radiographic and color photographic films incorporating the disclosure of Kofron et al. Were introduced commercially. Fifteen years later, it is clearly understood that different tabular grain emulsions are preferred depending on the type of product contemplated. Indirect radiography has been found to be unattractive since ultrathin tabular grain emulsions produce silver with an unfavorable temperature (ie, brownish black) image tone. In camera speed color photographic films, ultrathin tabular grain emulsions are usually attractive, especially when spectrally sensitized to wavelength regions where intrinsic grain sensitivity is low, for example, wavelengths longer than about 430 nm. Turned out to be. It is theoretically possible for ultrathin tabular grains containing one or more spectral sensitizing dyes having an absorption peak below 430 nm to exhibit comparable performance. However, the art has increased sensitivity depending on the usually intrinsic blue sensitivity of camera speed emulsions, which has slowed the transition to ultrathin tabular grain emulsions for performing blue exposure recording. The reduction in grain volume caused by reducing the thickness of the tabular grains adversely affects the use of intrinsic blue sensitivity which results in a significantly greater increase in blue speed than is realized by using blue absorbing spectral sensitizing dyes. Therefore, it is common to select thicker tabular or non-tabular grains for the blue recording emulsion layer of a camera speed film. Recently, US Patent No. 5,250,40
No. 3 (Antoniades et al.), Prior to the present invention,
In many respects, tabular grain emulsions are disclosed which are representative of the best emulsions available for recording light in color photographic elements, especially in the minus blue (red and / or green) portion of the spectrum. Antoniades et al. Disclosed tabular grain emulsions in which tabular grains having (111) major faces accounted for more than 97% of total grain projected area. These tabular grains have an average equivalent circle diameter (average EC
D) is at least 0.7 μm and the average thickness is 0.0
Less than 7 μm (tabular grain emulsions having an average thickness of less than 0.07 μm are hereinafter referred to as “ultra-thin” tabular grain emulsions). Ultrathin tabular grain emulsions provide efficient silver utilization in both the emulsion and lower emulsion layers, speed-
The attractiveness of the granularity relationship and the high level of image sharpness make it suitable for use in color photographic elements, especially minus blue recording emulsion layers. Research Disclosure (hereinafter referred to as RD), Volume 253, Item 25330, by Buhr et al.
As disclosed in May 1985, 0.18 to
As is recognized as a feature of tabular grains having a thickness in the range of 0.08 μm, the feature that distinguishes ultrathin tabular grain emulsions from other tabular grain emulsions is the largest in the visible spectrum. It does not show reflection. RD is located at Kennet at PO10 7DQ Emsworth 12 North Street Dudley Annex, Hampshire, UK
h Published by Mason Publications. In a multilayer photographic element, the upper emulsion layer having an average tabular grain thickness in the range of 0.18 to 0.08 µm comprises:
Care must be taken in the selection as the reflection properties vary greatly within the visible spectrum. The choice of ultrathin tabular grain emulsions in the construction of the multilayer photographic element obviates the need to select different average grain thicknesses for the various emulsion layers above other emulsion layers depending on spectral reflectance. Thus, ultrathin tabular grain emulsions not only can improve photographic performance, but also have the advantage of simplifying the construction of multilayer photographic elements. As an alternative, RD (Vol. 308, December 1989, Item 3
As disclosed in US Pat. No. 08119, Section I, paragraph D), Antoniades et al. Considered incorporating ionic dopants into ultrathin tabular grains. Attempts to reduce sensitization have been considered for a long time, and Carroll
U.S. Pat. No. 2,487,850 discloses a tin compound, Lowe et al. Discloses a polyamine compound in U.S. Pat. No. 2,512,925, and Fallens et al.
No. 9,823 discloses that thiourea dioxide compounds are each useful as a reduction sensitizer.

[0004] Furthermore, Collier is a Photograph.
phic Science and Engineeri
ng 23: 113 (1979) compares the properties of silver nuclei made by various reduction sensitization methods.
She has, for example, dimethylaminoborane, stannous chloride,
A method using hydrazine, high pH aging, and low pAg aging was employed. The method of reduction sensitization is further described in U.S. Pat.
No. 8,698, No. 3,201,254, No. 3,4
No. 11,917, No. 3,779,777, No. 3,
No. 930,867. Regarding the method of using the reducing agent as well as the selection of the reduction sensitizer,
No. 33572, No. 58-1410, JP-A-57-17
No. 9835. Further, a technique for improving the storage stability of the reduction-sensitized emulsion is disclosed in JP-A-57-8283.
Nos. 1 and 60-178445. or,
Reduction sensitization is described in TH James, The Photographic Process, 4th Edition, published by Macmillan, 1977, (TH James, The.
Theory of the Photographi
c Process, 4thed, Macmilla
n, 1977), p. 152, the silver nucleus formed by the two atoms generated by reduction sensitization captures holes, thereby decomposing into silver ions and unstable silver atoms, and further thermally. A mechanism has been considered in which unstable silver atoms are decomposed into silver ions and conductor electrons, and the electrons contribute to latent image formation. According to this mechanism, it is possible to increase sensitivity up to twice. Japanese Patent Application Laid-Open No. 8-21525 discloses a patent in which an ultra-thin tabular grain emulsion is used in combination with reduction sensitization on the surface. In this case, the reduction sensitization is performed on the surface, and the surface is reduced. In the case of sensitization, fogging was too high even when an oxidizing agent such as thiosulfonic acid was used in combination, and was not sufficient as an effect. Also, JP-A-2-191938,
Japanese Patent Application Laid-Open No. 8-29911 discloses a patent for a combination of reduction sensitization and thiosulfonic acid, but this technique alone does not sufficiently improve the sharpness, although the sensitivity-fog is improved.

[0005]

Despite the numerous advantages of general tabular grain emulsions and the particular improvements provided by ultrathin tabular grain emulsions and color photographic elements, including the improvements disclosed by Antoniades et al. Constitutes the highest performance emulsions and photographic elements that can be achieved not only in photographic elements containing these emulsions, but also in ultrathin tabular grain emulsions previously unattainable in the art and in color photography. There remains an unmet need for another option. In addition, ultrathin tabular grain emulsions have efficient silver utilization, attractive speed-granularity relationships, and high levels of image sharpness, in both the emulsion and lower emulsion layers. For this reason, it is particularly suitable for use in a minus blue recording emulsion layer, but is insufficient in sensitivity because it is very thin for use in a blue recording emulsion.

The present invention has been made in view of the above circumstances, and an object of the present invention is to use ultra-thin tabular grains having sufficient sensitivity for use in a blue recording emulsion, low fog and good sharpness. It is another object of the present invention to provide a photographic material using a silver halide emulsion and an ultra-thin tabular grain emulsion which achieves further improvement in the performance of minus blue recording.

[0007]

The above object of the present invention has been attained by the following constitutions.

<1> It has a (111) main surface, an average silver bromide content of 70 mol% or more, and an average equivalent circle diameter of 0.7 μm.
m or more, and wherein the tabular silver halide grains having an average grain thickness of less than 0.07 μm occupy 90% or more of the total projected area. A silver halide emulsion characterized by being subjected to reduction sensitization inside silver halide grains and containing at least one compound selected from the compounds represented by the following formulas (1) to (3): .

The general formula (1) R-SO ₂ SM (2) R-SO ₂ SR ₁ (3) R-SO ₂ SL _m -SSO ₂ -R _{2 In the} formula, R and R ₁ , R ₂ is an aliphatic group, an alicyclic group (remaining compound)
Represents an aromatic group or a heterocyclic group, which may be the same or different, and M represents a cation. L represents a divalent linking group, and m is 0 or 1. The compounds of the above general formulas (1) to (3) may be polymers containing, as a repeating unit, a divalent group derived from the structure shown in the above (1) to (3). When possible, R, R ₁ , R ₂ , L
May combine with each other to form a ring.

In a preferred embodiment, the tabular silver halide grains contain a dopant, and the silver halide grains have a latent image forming chemical sensitizing site on the surface thereof, and the site has at least one chemically sensitized site. And silver halide projections.

<2> A photographic light-sensitive material comprising the silver halide emulsion described in any one of the above.

Various studies have been made to increase the sensitivity of silver halide emulsions, and steady progress has been made.
However, there are great demands for efficient use of silver as a photographic material, simultaneous improvement of sensitivity, fog-granularity relation, sharpness of an image, and compatibility between the above characteristics and storage stability, which are still not at a satisfactory level.

Accordingly, the present inventors have conducted intensive studies and as a result,
In the manufacturing process of silver halide emulsions, reduction sensitivity was applied to the inside of the grains, whereas the sensitivity which was disadvantageous for blue recording by making the silver halide grains ultra-thin, the resulting high fog was reduced to a specific structure. Can be suppressed by using a thiosulfonic acid derivative having the sensitivity, fog,
The present invention has been made based on the finding that sharpness can be dramatically improved. Further, with respect to minus blue recording, the above characteristics are further improved.

Hereinafter, the present invention will be described in detail.

The present invention relates to the enhancement of spectrally sensitized photographic emulsions. The silver halide emulsion used in the present invention (hereinafter, referred to as “silver halide emulsion”)
It is simply called the emulsion of the present invention. ) Is specifically intended for incorporation into camera speed color photographic film. In the emulsion of the present invention, the tabular grains have (a) (111) major faces, (b) more than 70 mol% bromide based on silver, and (c) 90% of the total grain casting area. % Ultra-thin tabular grain emulsions which account for more than 1% of the total (d) exhibit an average equivalent circular diameter (mean ECD) of at least 0.7 μm and (e) exhibit an average thickness of less than 0.07 μm. It can be realized by chemical and spectral sensitization. Criteria (a)-(e) are too stringent to be satisfied by the majority of known tabular grain emulsions, but a few published precipitation methods can produce emulsions that meet these criteria. it can. Antoniades et al., Supra, indicate preferred silver iodobromide emulsions that meet these criteria. EP 362,699 A3 (Zola and Bryant) also discloses silver iodobromide emulsions meeting these criteria.

For grains and emulsions containing multiple halides, the halides are described in order of increasing concentration. In the present invention, the term “ultra-thin” refers to 0.07 μm
Used to indicate tabular grains having an average grain thickness of less than, and are therefore also referred to as ultrathin tabular grains.
In the case of a camera sensitivity film, the tabular grains generally contain at least 0.25 mol%, preferably at least 1.0 mol%, of iodide with respect to silver.
These low levels of iodide are also contemplated in ultrathin tabular grains contained in the emulsions of the present invention. But,
Ultrathin tabular grain iodide is not required to realize the speed-granularity benefits of the present invention. Ultra-thin silver bromide grains undergo morphological collapse (e.g.,
(I.e., enlargement), it is conceivable to incorporate iodide instead as a convenience for morphologically stabilizing the ultrathin tabular grains. The ultrathin tabular grains contained in the emulsions of the invention will in all cases contain less than 10 mol% iodide, preferably less than 6 mol% iodide and optimally less than 4 mol% iodide. Is preferred. Ultrathin tabular grains can also contain small amounts of chloride ions. U.S. Pat. No. 5,372,927 (D
ultra-thin tabular grains containing from 0.4 to 20 mole percent chloride and up to 10 mole percent iodide, with the balance halide being bromide, as disclosed in US Pat. The emulsion is described in U.S. Pat. No. 5,061,609.
No. 5,061,616 (Piggin et al.) Total silver within the pAg-Temperature (° C.) boundary (preferably within the boundary of Curve B) of Curve A shown by Delton corresponding to Curves A and B Can be prepared by growing particles occupying 5-90% of the total. Under these precipitation conditions, the presence of chloride ions actually helps reduce the thickness of the tabular grains.

For chloride ions (when present), it is preferred to use precipitation conditions that can help reduce the thickness of the tabular grains, but chloride ions are used to reduce the average thickness of the tabular grains. It is recognized that ordinary ultrathin tabular grains can be added during precipitation to an extent compatible with retention of less than 0.07 μm. Ultrathin tabular grains occupying at least 90% of the total grain projected area (total projected area) must contain at least 70 mol% bromide relative to silver;
And it is preferable to contain iodide at least 0.25 mol%. These ultrathin tabular grains preferably contain silver iodobromide and silver chloroiodobromide grains. All references to the composition of ultrathin tabular grains exclude silver halide epitaxy. The iodide in the ultrathin tabular grains can be conveniently or uniformly distributed within the tabular grains.

The emulsion examples of Antoniades et al illustrate a relatively uniform iodide distribution. U.S. Patent No. 4,
No. 433,048 (Solberg et al.) Discloses a non-uniform iodide profile which can reduce granularity without reducing speed. A
Ultrathin tabular grains produced according to the disclosures of Zona and Bryant and Delton, et al., have a (111) major surface. Such tabular grains typically have a triangular or hexagonal major surface. The tabular structure of the grains results from the inclusion of parallel twin planes.

The tabular grains contained in the emulsion of the present invention include:
It accounts for 90% or more of the total grain projected area. Ultrathin tabular grain emulsions in which tabular grains account for greater than 97% of total grain projected area can be prepared and are preferred by the preparation methods disclosed by Antoniades et al. Anton
report silver halide emulsions in which tabular grains account for over 99% (substantially all) of the total grain projected area. Similarly, Delton
It is reported that "substantially all" of the grains that precipitate when forming ultrathin tabular grain emulsions were tabular. Providing emulsions in which tabular grains account for a high percentage of the total grain projected area is important to achieve the highest achievable image sharpness levels, especially in multilayer color photographic films. It is also important to utilize silver efficiently and to achieve the most desirable speed-granularity relationship. Tabular grains accounting for 90% or more of the total grain projected area are:
It is essential that the average ECD is at least 0.7 μm. The benefits realized by keeping the average ECD at least 0.7 μm are shown in Tables III and IV of Antoniades et al. Extremely large average ECD
May be prepared for scientific grain studies, but for photographic applications the average ECD is usually less than 10 μm and most often less than 5 μm. The optimal average ECD range for medium to high image structure quality is 1 to
The range is 4 μm.

In the emulsion containing ultrathin tabular grains of the present invention, tabular grains occupying 90% or more of the total grain projected area have an average grain thickness of 0.07 μm.
m. With an average grain thickness of 0.07 μm, there is little variation in reflectance between the green and red regions of the spectrum. Further, the average particle thickness is 0.08 to 0.20.
Compared to emulsions containing tabular grains having a range of μm, the difference between minus blue reflectance and blue reflectance is not great. By decoupling the magnitude of the reflectance from the exposure wavelength in the visible region, green and red recording emulsions (and to a lesser extent blue recording emulsions) can be constructed using emulsions containing the same or similar tabular grains. The film configuration is simplified. If the average grain thickness of the tabular grains is further reduced to less than 0.05 μm, the average reflectance observed in the visible spectrum will also decrease. Therefore,
Preferably, the average grain thickness is kept below 0.05 μm. Generally, the smallest average grain thickness conveniently achieved by the precipitation method is preferred.

Thus, the average grain thickness is about 0.0
Ultrathin tabular grain-containing emulsions in the range of 3 to 0.05 µm are easily realized. U.S. Patent No. 4,672,027 (Daubendiek et al.) Discloses an average grain thickness of 0.01.
7 μm is reported. Utilizing the grain growth method disclosed by Antoniades et al., These emulsions can be prepared without any appreciable thickness increase, e.g., with an average ECD of at least 0, while maintaining an average grain thickness of less than 0.02 .mu.m. It can grow to 0.7 μm. The minimum average grain thickness of the tabular grains is the first two grains formed in the grains during precipitation.
It is limited by the distance between two parallel twin planes. 0.002μ
Small minimum twin plane spacings of m (ie, 2 nm or 20 angstroms) have been observed in emulsions such as Antoniades, but Kofron et al. suggest a practical minimum average grain thickness of about 0.01 μm. In the present invention, emulsions containing preferred ultrathin tabular grains are those in which the variation between grains is kept at a low level. Anton
Iades et al. report emulsions containing ultrathin tabular grains in which more than 90% of the tabular grains have a hexagonal major surface. Antoniades also reports emulsions containing ultrathin tabular grains that have a coefficient of variation (COV) to average ECD of less than 25% and sometimes less than 20%.
It can be seen that photographic speed and granularity increase with increasing average ECD. From a comparison of the sensitivity and granularity of optimally sensitized emulsions with different average ECDs,
For each doubling of speed (ie, 0.3 log E increase in speed, where E is the exposure (lux-seconds)), the granularity of the emulsion exhibiting the same speed-granularity relationship is 7 granularities. Units have been proven to increase. In the emulsions of the present invention, it was observed that the graininess of the emulsion was significantly increased when a small percentage of grains having a higher average ECD were present. Antoniades et al., C
If the OV is restricted, the average ECD of the tabular grains present always approaches the average value, so that a low COV emulsion was preferred. According to the present invention, COV is not the best way to determine the granularity of an emulsion. The need for low emulsion COV values limits both the population of grains larger and smaller than the average ECD, while only the former population provides a higher level of granularity. The authenticity of the overall COV measurement in the art is based on the assumption that the particle size-frequency distribution (whether the variance is wide or narrow) is a normal error function distribution that is inherent in sedimentation methods and cannot be easily controlled. I have. It is specifically intended to modify the ultrathin tabular grain precipitation method disclosed by Antoniades et al. To selectively reduce the particle size-frequency distribution of ultrathin tabular grains exhibiting an ECD greater than the average ECD of the emulsion. Is done. The overall COV value does not decrease appreciably since the particle size-frequency distribution of particles having an ECD below the average is not correspondingly reduced. However, the benefits of reducing emulsion granularity have been clearly demonstrated. It has been found that a reduction in the disproportionate size range in the particle size-frequency distribution of ultrathin tabular grains greater than the average ECD can be achieved by modifying the precipitation method for emulsions containing ultrathin tabular grains in the following manner. did. That is, the nucleation of ultrathin tabular grains is performed using a gelatinous peptizer that has not been treated to reduce the natural methionine content, while the existing gelatinous peptizer and the later introduced gelatinous peptizer After substantially removing the methionine content from the above, the particles are grown. A convenient approach to accomplish this is to interrupt precipitation after nucleation and before growth has progressed to a sufficient degree to introduce a methionine oxidizing agent. Any of the conventional techniques for oxidizing the gelatinous peptizer methionine can be used. U.S. Pat. No. 4,713,320 (Masksk)
y, hereinafter referred to as “Maskasky II”), discloses that oxidation reduces methionine levels to less than 30 μmol per gram of gelatin, preferably to less than 12 μmol by using a strong oxidizing agent.

In fact, the oxidizing agent treatment used by Maskasky II reduces methionine below the detection limit.
Agents used to oxidize methionine in gelatinous peptizers include, for example, NaOCl, chloramine, potassium monopersulfate, hydrogen peroxide and peroxide releasing compounds, and ozone. US Patent No. 4,94
No. 2,120 (King et al.) Discloses oxidizing the methionine component of a gelatinous peptizer with an alkylating agent. European Patent No. 434,012 (Takada)
And the like) disclose precipitation in the presence of thiosulfonate, which is one of the compounds represented by the general formulas (1) to (3).

Gelatin peptizers include gelatin, for example, alkali-treated gelatin (livestock, bone or hide gelatin) or acid-treated gelatin (pig skin gelatin) and gelatin derivatives, for example, acetylated or phthalated gelatin. It is.

In the present invention, the average particle thickness, the average equivalent circle diameter (average ECD), the variation count with respect to the average ECD,
The average silver bromide content is determined by the following method.

The average grain thickness is measuring the level of 1,1'-diethyl-2,2'-cyanine dye required for saturation coverage, the solution absorption coefficient of the dye is 77,300 liters / mole ^{- cm} , and the site area per mole is 0.
Using 566 nm ² , the equation for the surface area is solved.

The average equivalent circle diameter (average ECD) is determined by the following method. A sample was prepared by coating a latex ball having a known particle size as an internal standard on a support and silver halide particles such that the main plane was oriented parallel to the substrate, and shadowing was performed by carbon deposition from a certain angle. Thereafter, a replica sample is prepared by a normal replica method. An electron micrograph of the sample is taken, and the projected area of each particle is determined using an image processing device or the like. In this case, the projected area of the particle can be calculated from the projected area of the internal standard. In the present invention, the average equivalent circle diameter (average ECD) refers to a value obtained by arbitrarily measuring 500 or more silver halide grains contained in a silver halide emulsion using the above-mentioned replica method and calculating the arithmetic average thereof. .

The variation coefficient with respect to the average ECD of silver halide grains is a value defined by the following equation using the value obtained from the above measurement.

Variation coefficient (%) with respect to average ECD = (standard deviation of particle size / average of particle size) × 100 The average silver bromide content in the present invention is determined by the following method. An aqueous solution of actinase, which is a gelatin-decomposing enzyme, is added to the silver halide emulsion, gelatin is decomposed, and only the silver halide grains are taken out by centrifugation and dissolved with a silver halide solvent (ammonium thiosulfate) or the like, and the quantified After dropping the filter paper, the bromine content is determined by a calibration curve method based on X-ray fluorescence analysis, and the value is defined as the average silver bromide content.

The ultrathin tabular grains contained in the emulsion of the present invention are characterized in that reduction sensitization has been performed inside. The emulsion of the present invention has the largest sensitizing effect when the grains are subjected to reduction sensitization, and has good storage fog. Intra-grain reduction sensitization can be achieved by performing reduction sensitization during the growth of silver halide grains. The phrase "perform reduction sensitization during growth" as used herein means that reduction sensitization may be performed during physical ripening of silver halide grains, or reduction during addition of a water-soluble silver salt and a water-soluble alkali halide. It means that sensitization may be carried out, or that a method in which reduction sensitization is carried out in a state in which these additions are temporarily stopped, and then a further precipitation step may be carried out.

The reduction sensitization performed in the present invention refers to a method in which a reduction sensitizer is added to silver halide, or growth or ripening of silver halide grains in a low pAg atmosphere of pAg 1 to 7, which is called silver ripening. It is also possible to select any one of a method of growing, and a method of growing or ripening in a high pH atmosphere of pH 8 to 11, which is called high pH ripening. Also, two or more of these methods can be used in combination. Especially,
The method of adding a reduction sensitizer is a preferable method because the level of reduction sensitization can be finely adjusted. As the reduction sensitizer used here, for example, stannous salts, amines and polyamines, hydrazine derivatives, formamidinesulfinic acid, silane compounds and borane compounds are known.
For the reduction sensitization performed in the present invention, these known reduction sensitizers can be selected and used, or two or more compounds can be used in combination. The addition amount of the reduction sensitizer depends on the emulsion production conditions and must be appropriately selected, but is suitably in the range of 10 ^-7 to 10 ^-2 mol per mol of silver halide.
These reduction sensitizers are dissolved in, for example, water or a solvent such as alcohols, glycols, ketones, esters, and amides, and added during grain growth. Although it may be added to the reaction vessel in advance, it is preferable to add it at an appropriate time during grain growth. Alternatively, a reduction sensitizer may be added in advance to an aqueous solution of a water-soluble silver salt or a water-soluble alkali halide, and silver halide grains may be precipitated using these aqueous solutions. In addition, a method in which the solution of the reduction sensitizer is added in several portions as the grains grow, and a method in which the solution is continuously added for a long time are also preferable methods. It is preferable that no reduced silver nuclei be present on the surface of the silver halide grains subjected to intragranular reduction in this way.

The following method can be used as a method for performing intra-grain reduction sensitization without the presence of reduced silver nuclei on the surface.
That is, when the reduction sensitization inside the grains is performed by the low pAg ripening and / or the high pH ripening as described above, the pAg is returned to a pAg in which the reduction exceeding 7 cannot be performed, and / or pAg cannot be reduced.
The H is returned to a pH below 8 that does not allow reduction, and then the outermost layer is coated. When reduction sensitization inside the grains is performed using a reduction sensitizer, for example, as disclosed in JP-B-58-1410, there is a method of adding an oxidizing agent such as iodine. However, when an oxidizing agent is added, it remains in a very small amount before the chemical sensitization step and inhibits the formation of a photosensitive nucleus, which is not photographically preferable.

A preferred method for the silver halide grains in the present invention is a method of coating the outermost nucleus by lowering the pH to 5 or less to hinder the reaction of the reduction sensitizer, or a method of reducing sensitization through a water washing step after reduction sensitization. A method of coating the outermost nucleus after removing the sensitizer, and a method of coating the outermost nucleus in a state where at least one compound represented by the following general formulas (1) to (3) is present: At least one selected from the group consisting of:

Formula (1) R-SO ₂ S-M (2) R-SO ₂ S-R ₁ (3) R-SO ₂ S-L _m -SSO ₂ -R ₂ Formulas (1) through ( ₂ ) The thiosulfonic acid-based compound 3) will be described in more detail. When R, R ₁ and R ₂ are an aliphatic group or an alicyclic (residual compound) group, a saturated or unsaturated, linear,
It is a branched or cyclic aliphatic hydrocarbon group, preferably an alkyl group having 1 to 22 carbon atoms, an alkenyl group having 2 to 22 carbon atoms, or an alkynyl group, which has a substituent. You may. Examples of the alkyl group include methyl, ethyl, propyl, butyl, pentyl, hexyl,
Octyl, 2-ethylhexyl, decyl, dodecyl, hexadecyl, octadecyl, cyclohexyl, isopropyl and t-butyl.

The alkenyl group includes, for example, allyl and butenyl. Examples of the alkynyl group include propargyl and butynyl.

When R, R ₁ and R ₂ are aromatic groups, they include monocyclic or condensed ring aromatic groups, and preferably have 6 to 6 carbon atoms.
20 and phenyl, naphthyl and the like.
These may be substituted.

When R, R ₁ and R ₂ are heterocyclic groups, they have at least one element selected from nitrogen, oxygen, sulfur, selenium and tellurium and have at least one carbon atom. It is preferably a 3- to 15-membered ring, more preferably a 3- to 6-membered ring and a condensed ring thereof. For example, pyrrolidine, piperidine, pyridine, tetrahydrofuran, thiophene, oxazole, thiazole, imidazole, benzothiazole, benzoxazole, Examples include benzimidazole, selenazole, benzoselenazole, tellurazole, triazole, benzotriazole, tetrazole, oxadiazole, and thiadiazole ring.

Examples of the substituent for R, R ₁ and R ₂ include an alkyl group (eg, methyl, ethyl, hexyl), an alkoxy group (eg, methoxy, ethoxy, octyloxy), and an aryl group (eg, phenyl, Naphthyl, tolyl), heterocyclic group, hydroxy group, halogen atom (eg, fluorine, chlorine, bromine, iodine), aryloxy group (eg, phenoxy), aryloxycarbonyloxy group (eg, phenoxycarbonyloxy group), alkylthio group (eg, , Methylthio, butylthio), arylthio groups (eg, phenylthio), acyl groups (eg, acetyl, propionyl, butyryl, valeryl), sulfonyl groups (eg, methylsulfonyl, phenylsulfonyl), acylamino groups (eg, acetylamino, benzoylamino) ), Ruhoniruamino group (e.g., methanesulfonylamino, benzenesulfonylamino), an acyloxy group (e.g., acetoxy, benzoxy), a carboxyl group, a cyano group, a sulfo group, an amino group, -SO ₂ S
Examples include an M group (M represents a monovalent cation) and a —SO ₂ SR group (R represents an alkyl group). The divalent linking group represented by L is an atom or an atomic group containing at least one selected from C, N, S and O.

Specifically, an alkylene group, alkenylene group, alkynylene group, arylene group, -O-, -S-,
-NH -, - CO -, - SO 2 - is made of a single or combination of such. L is preferably a divalent aliphatic group or a divalent aromatic group.

As the divalent aliphatic group, for example,-(C
H ₂₎ n- (n is _{1~12), - CH 2 -CH =} CH-C
_{H 2 -, - CH 2 C≡CCH} 2 -, - CH 2 -1,4- cyclohexylene -CH ₂ -, xylylene group, and the like. Examples of the divalent aromatic group for L include a phenylene group and a naphthylene group. These linking groups may be further substituted with the substituents described above.

M represents a cation, and is preferably a metal ion or an organic cation. Examples of the metal ion include a lithium ion, a sodium ion, and a potassium ion. Examples of the organic cation include an ammonium ion (ammonium, tetramethylammonium, tetrabutylammonium, etc.), a phosphonium ion (tetraphenylphosphonium), and a guanidyl group.

When the compounds represented by the general formulas (1) to (3) are polymers, examples of the repeating unit include the following.

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These polymers may be homopolymers or copolymers with other copolymerized monomers. Specific examples of the compounds represented by the general formulas (1) to (3) are shown below, but are not limited thereto.

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The compounds represented by the general formulas (1) to (3) are described in JP-A-54-1019 and British Patent 972,211.
No., Journal of Organic Chem
The compound can be synthesized by the method described in “Istry (Journal of Organic Chemistry)”, vol. 53, p. 396 (1988) or a method analogous thereto.

In the present invention, the amount of the compound represented by any of formulas (1) to (3) per mol of silver is 10 ^-7.
It is desirable to select from the range of 10 to 10 ^-1 mol. Preferably it is in the range of 10 ^-6 to 10 ^-2 mol, more preferably 10 ^-6.
The range is ^-5 to 10 ^-3 mol. General formulas (1) to (3)
The compound represented by may be added at any stage during the process of producing a silver halide emulsion, for example, during silver halide grain formation, before or after chemical sensitization, but preferably before chemical sensitization. More preferably, grains are being formed, and the compounds represented by the general formulas (1) to (3) may be added at any stage before or after the start of reduction sensitization. It is preferred to add it later.

In order to add the compounds represented by the general formulas (1) to (3) during the production process, a method usually used for adding an additive to a photographic emulsion can be applied. For example, a water-soluble compound is an aqueous solution having an appropriate concentration, and a compound that is insoluble or hardly soluble in water is a suitable organic solvent that is miscible with water, such as alcohols, glycols, ketones, esters, and amides. Of these, the compound can be dissolved in a solvent that does not adversely affect photographic properties and added as a solution.

In the present invention, it is more preferable to add a dopant to the ultrathin tabular grains. The "dopant" used in the present invention means a substance other than silver or halide ions contained in the face-centered cubic crystal lattice structure of silver halide forming ultrathin tabular grains.
The introduction of the dopant contributes to an increase in the thickness of the ultrathin tabular grains during precipitation when introduced at a high concentration and / or before, during or immediately after nucleation of the grains.
Ultrathin tabular grains can be formed with dopants present during grain growth, as shown in the examples of the present invention. On this occasion,
The introduction of the dopant is delayed until after the grain formation, and a quota is introduced at the beginning of the grain growth, preferably continuing as it is, or throughout the entire later stage of ultrathin tabular grain growth.
It has also been found that these same dopants can be introduced with silver salts that epitaxy adhere to the ultrathin tabular grains, while completely avoiding the increase in thickness of the ultrathin tabular grains.

In the present invention, any ordinary dopant known to be useful for silver halide can be used. Photographically useful dopants selected from a wide range of periods and groups within the periodic table of elements have been reported. As the dopant selected from the periodicity and the group used in the present invention, American Chem
Employed by Ical Society, Chemi
cal and Engineering News,
Based on the Periodic Table of the Elements published February 4, 1985, page 26. Common dopants include Fe,
Co, Ni, Ru, Rh, Pd, Re, Os, Ir, P
t, Mg, A1, Ca, Sc, Ti, V, Cr, Mn,
Cu, Zn, Ga, Ge, As, Se, Sr, Y, M
o, Zr, Nb, Cd, In, Sn, Sb, Ba, L
a, W, Au, Hg, Tl, Pb, Bi, Ce, U, etc. Periodic tables of the third to seventh periods (most commonly the fourth to seventh periods)
6 cycles). The dopant is
(A) increase in sensitivity, (b) decrease in high or low illuminance reciprocity failure, (c) increase, decrease or decrease in contrast variation,
(D) reduced pressure sensitivity, (e) reduced dye desensitization,
(F) increased stability (including reduced thermal instability);
(G) decrease in minimum density and / or (h) increase in maximum density. For certain applications, any multivalent metal ion is effective.

The following are literature examples of ordinary dopants that can produce one or more of the above effects when incorporated as a dopant into silver halide.

B. H. Carroll, "Iridiu
m Sensitization: A Literat
ure Review ”, Photographic
Science and Engineering, Vol. 24, No. 6, November / December 1980, 265-265
267; U.S. Patent No. 1,951,933 (Hoch
No. 2,628,167 (De W)
itt), No. 3,687,676 (Spence, etc.)
Nos. 3,761,267 (Gilman et al.); 3,890,154 (Ohkubo et al.); 3,90
No. 1,711 (Iwaosa et al.), 3,901,71
No. 3 (Yamasue et al.); No. 4,173,483 (Habu et al.); No. 4,269,927 (Atwel)
l), No. 4,413,055 (Weyde);
477,561 (Menjo et al.), 4,581,3
No. 27 (Habu et al.) And No. 4,643,965 (Ku
No. 4,806,462 (Yamash)
No. 4,828,962 (Grzesko)
No. 4,835,093 (Januso)
No. 4,902,611 (Leubner)
No. 4,981,780 (Inoue et al.); No. 4,991
7,751 (Kim); 5,057,402 (S
No. 5,134,060 (Maekawa)
No. 5,153,110 (Kawai et al.); 5,164,292 (Johnson et al.); 5,1
Nos. 66,044 and 5,204,234 (Asam
i); 5,166,045 (Wu); 5,22
9,263 (Yoshida et al.); 5,252,4
Nos. 51 and 5,252,530 (Bell); European Patent Nos. 244,184 (Komorita et al.); And 488,737 and 488,601 (Miyos)
No. 368,304 (Ihama et al.); No. 405,938 (Tashiro); No. 509,
Nos. 674 and 563,946 (Murakami
Etc.) and Japanese Patent Application No. 2-249588 and WO 93/2
No. 390 (Budz).

When the metal used as dopant is present in the precipitate in the form of a coordination complex, in particular a tetra- and hexa-coordination complex, both metal ions and coordinating ligands can be absorbed in the particles. 4,847,191 (Grzes
No. 4,933,272, No. 4,984.
No. 1,781 and 5,037,732 (McDug
le, etc.), No. 937,180 (Marchetti)
Nos. 4,945,035 (Keert et al.), 5,112,732 (Hayashi), and EP 509,674 (Murakami et al.), 513,
No. 738 (Ohya et al.), WO 91/10166 (Janusonis), WO 92/16876 (Beavers), Halo, Aquo as indicated by DD 298,320 (Pietsch et al.), Germany. , Cyano, cyanate, flumate, thiocyanate, selenocyanate, tellurocyanate, nitrosyl, thionitrosyl, azide, oxo, carbonyl and ethylenediaminetetraacetic acid (EDTA) ligands, wherein in some cases the improvement of emulsion properties by the ligands is disclosed. Is recognized. 5,360,712 (Olm, etc.)
Discloses hexacoordination complexes containing organic ligands, while
U.S. Pat. No. 4,092,171 (Biglow) discloses organic ligands in Pt and Pd tetracoordination complexes. It is specifically contemplated to incorporate dopants into ultrathin tabular grains to reduce reciprocity failure. Iridium is a preferred dopant for reducing reciprocity failure. Carroll, Iwaosa, etc., Habu, etc.,
Grzekowiak et al., Kim, Maekawa
Etc., Johnson et al., Asami, Yoshida
Et al., Bell, Miyoshi et al., Tashiro's disclosure and EP 509,674 (Murakami).
Etc.) are representative. These disclosures are applicable to the emulsions of the invention by simply incorporating the dopant into the silver halide precipitate. Item 36736, RD, Vol. 367, November 1994, provides a straightforward description of the criteria for selecting shallow electron trap (SET) dopants. In certain preferred embodiments, it is contemplated to use a hexa-coordination complex satisfying the following general formula (4) as a dopant.

Formula (4) [ML ₆ ] n In the formula, M is a charged frontier orbital polyvalent metal ion, preferably Fe ⁺² , Ru ⁺² , Os ⁺² , Co ⁺³ , Rh ⁺³ , Ir.
⁺³ , Pd ⁺⁴ or Pt ⁺⁴ , wherein L ₆ represents _six independently selectable coordination complex ligands, with the proviso that
At least four of the ligands are anionic ligands;
At least one (preferably at least three and optimally at least four) of the ligands is more electronegative than any halide ligand. And n is -2,-
3 or -4. Specific examples of dopants that can provide a shallow electron trap are: SET-1 [Fe (CN) ₆ ] ^-4 SET-2 [Ru (CN) ₆ ] ^-4 SET-3 [Os (CN) ₆ ] ^-4 SET-4 [Rh (CN) ₆ ] ^-3 SET-5 [Ir (CN) ₆ ] ^-3 SET-6 [Fe (pyrazine) (CN) ₅ ] ^-4 SET-7 [RuCl ( CN) ₅ ] ^-4 SET-8 [OsBr (CN) ₅ ] ^-4 SET-9 [Rh F (CN) ₅ ] ^-3 SET-10 [IrBr (CN) ₅ ] ^-3 SET-11 [Fe CO (CN) _5] ^-3 SET-12 [Ru F ₂ (CN) _4] ^-4 SET-13 [Os Cl ₂ (CN) _4] ^-4 SET-14 [Rh I ₂ (CN) _4] ^-3 SET-15 [Ir Br ₂ (CN) _4] ^-3 SET-16 [Ru (CN) ₅ (OCN)] ^-4 SET-1 _{[Ru (CN) 5 (N 3} ) ] ^-4 SET-18 [Os (CN) ₅ (SCN)] ^-4 SET-19 [Rh (CN) ₅ (SeCN)] ^-3 SET-20 [Ir (CN ) ₅ (HOH)] ^-2 SET-21 [Fe (CN) ₃ Cl ₃ ] ^-4 SET-22 [Ru (CO) ₂ (CN) ₄ ] ^-2 SET-23 [Os (CN) Cl ₅ ] ^{- 4} SET-24 [Co (CN) ₆ ] ^-3 SET-25 [Ir (CN) ₄ (oxalate)] ^-3 SET-26 [In (NCS) ₆ ] ^-3 SET-27 [Ga (NCS) ₆ ] ^-3 Further, US Pat. No. 5,024,931 (Evans
It is also contemplated to use an oligomeric coordination complex to increase speed, as disclosed in US Pat. The dopant is effective at normal concentrations (where the concentration is a concentration based on total silver including both silver in tabular grains and silver in protrusions). Generally, the shallow electron trap-forming dopant should be added at least one mole per silver mole.
It is intended to be incorporated at from × 10 ^-6 mole to the solubility limit (typically a concentration of about 5 × 10 ^-4 mole or less per mole of silver). Preferred concentrations are from about 10 ^-5 to 10 ^-4 per silver mole.
Range of moles.

The emulsion of the present invention has a tabular surface having at least one silver halide projection having a latent image forming chemical sensitized site on the grain surface and the latent image forming chemical sensitized site being epitaxially arranged. It is preferable that the particles include shaped particles. That is, it means that the tabular grains have been subjected to at least chemical sensitization such as chalcogen sensitization represented by sulfur and / or gold sensitization to the epitaxially arranged silver halide projections.

The silver halide projections are epitaxially arranged on selected portions of the base tabular grains (hereinafter sometimes referred to as “host tabular grains”), so that they are emitted by photon absorption in imagewise exposure. It is generally disclosed that conduction band electrons competition for sensitized sites is reduced, thereby improving sensitivity. U.S. Pat. No. 4,435,501
Discloses improvement in sensitivity by epitaxially depositing a silver salt on selected sites on the surface of host tabular grains. The US patent states that the increase in sensitivity is due to limiting the epitaxial deposition of the silver salt to a small fraction of the surface area of the host tabular grains. In other words, the epitaxial arrangement of the ultrathin tabular grains on a limited portion of the main plane is more efficient than the epitaxial arrangement covering all or most of the main plane, and more preferably, substantially at the edge of the host tabular grain. Is epitaxially limited, and the amount of coating on the main plane is limited, and more efficient and preferable are:
This is an epitaxial arrangement limited to the corner of the host tabular grain, its vicinity, or another distinct site. The spacing of the corners of the main plane of the host tabular grains themselves reduces photoelectron competition sufficiently to achieve near maximum sensitivity. U.S. Pat. No. 4,435,501 discloses that reducing the rate of epitaxial deposition can reduce the number of sites of epitaxial placement on host tabular grains.

Therefore, also in the present invention, the silver halide projections epitaxially arranged on the surface area of the host tabular grain are preferably limited to a small portion of the surface area of the host tabular grain, and are limited to the corner or its vicinity. Is particularly preferred. Specifically, it is preferably less than 50%, and more preferably less than 30%. In addition, the silver amount of the silver halide protrusions arranged epitaxially is:
It is preferably from 0.3 to 25%, more preferably from 0.5 to 15%, based on the silver content of the host tabular grains.

In one of the most preferred embodiments of the present invention, it is preferable that the silver halide projections to be epitaxially arranged are formed at the corners of the host tabular grains or at restricted positions near the corners, and this is achieved. As a method for this, a known method can be applied. In the above-mentioned U.S. Pat. No. 4,435,501, a spectral sensitizing dye or an aminoazaindene is used as a site director.
A method of adsorbing as ctrl) is disclosed and can be preferably applied in the present invention.

In order to avoid structural collapse of ultrathin tabular grains as host tabular grains, the total solubility of silver halide projections arranged epitaxially is determined by the total solubility of silver halide forming host tabular grains. It is preferably higher than that. Therefore, it is preferable that the silver halide projections to be epitaxially arranged are specifically silver chloride.

Silver chloride facilitates epitaxial deposition because it forms a face-centered cubic lattice structure like silver bromide.
In order to preserve the structural integrity of the ultrathin tabular grains, the epitaxial deposition is preferably performed under conditions that limit the solubility of the halide forming the ultrathin tabular grains. However, in some cases, it is intended that the halide of the epitaxially arranged silver halide projection is from a host tabular grain. That is, silver chloride protrusions containing a small amount of bromide and optionally iodide are specifically contemplated.

The emulsion of the present invention is preferably subjected to chemical sensitization with chalcogen represented by sulfur and / or gold. In the case of host tabular grains having silver halide projections arranged epitaxially, the sensitivity is increased to an extent comparable to that obtained by substantially optimal chemical sensitization using sulfur and / or gold by itself. However, it is preferable that the tabular grains on which silver halide is epitaxially arranged are subjected to chemical sensitization because sensitivity is further increased.

A known method can be applied to the chemical sensitization method, and is described in, for example, RD, December 1989, Item 308119, Section III “Chemical sensitization”. Various known chemical sensitizers can be applied. Particularly in the case of tabular grains having silver halide protrusions arranged epitaxially, the sulfur sensitizer is combined with a middle chalcogen (typically sulfur) and a noble metal (typically gold) chemical sensitizer. Preferably, it is used. The intended sulfur sensitizers include U.S. Patent Nos. 3,271,157 and 3,574.
Thioethers described in US Pat. Nos. 628 and 3,737,313. Preferred sulfur sensitizers are described in U.S. Patent Nos. 2,222,264 and 2,448,534.
And thiocyanates described in JP-A-3,320,069. Preferred types of middle chalcogen sensitizers are described in U.S. Pat. Nos. 4,749,646 and 4,8
No. 10,626 are tetra-substituted middle chalcogen ureas.

The emulsion of the present invention is preferably subjected to spectral sensitization in order to increase sensitivity to light in a specific wavelength range. Various known spectral sensitizing methods and spectral sensitizing dyes can be applied, and are described, for example, in RD, December 1989, Item 308119, Section IV, “Spectral Sensitization and Desensitization”. In the case of tabular grains having silver halide projections arranged epitaxially, a spectral sensitizing dye is often already adsorbed as a site directing substance at the time of epitaxial deposition as described above, which is particularly advantageous. In this case, it is preferable to appropriately select and use the spectral sensitizing dye to be added at the time of epitaxial deposition, and it is also possible to further add a spectral sensitizing dye in the sensitizing step as needed.

The emulsion of the present invention can be used in various photographic materials by any conventional method. As one important aspect, the emulsion of the present invention is suitable for use in a multilayer photographic material having at least two silver halide emulsion layers. For example, in the case of a multilayer photographic light-sensitive material such as a color negative film or a color reversal film, the silver halide emulsion layer coated on the upper layer is often sensitive to light having a shorter wavelength than that of the lower layer. The emulsion of the present invention has excellent transparency because the scattering of minus blue light intended to be exposed in the lower layer is greatly reduced and the emulsion can be preferably applied to the upper silver halide emulsion layer.

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EXAMPLES The present invention will be described below in detail with reference to examples, but embodiments of the present invention are not limited thereto. Incidentally, the halide ion concentration is represented by mol% (M%) based on silver.

Example 1 <Emulsion A> (Comparative Example of Thin Tabular Grains) In a vessel equipped with a stirrer, 3.75 g of lime-processed bone gelatin, 4.76 g of KBr, an antifoaming agent, and a pH of 1.8 at 39 ° C. AgNO ₃ solution containing 6 liters of water and halide (KBR and KI each 98.5 M each containing sufficient amount of sulfuric acid to adjust to
% And 1.5M%) solution (both 2.5M) in a quantity sufficient to produce 0.01335 moles of silver iodobromide during nucleation achieved by simultaneous addition, pBr and pH were almost maintained at the values initially set in the solution in the reactor. Following nucleation, the temperature was increased to 54 ° C for 9 minutes. After holding the reactor and its contents at this temperature for 9 minutes, 100 g of lime-processed bone gelatin
In 1.5 liters of water was added to the reactor at 54 ° C. Next, the pH was raised to 5.90 and 1M K
The Br solution was added to the reactor. 24.5 minutes after nucleation, the growth phase begins, during which 2.5 M AgN
O ₃ , 2.8 M KBr and AgI (Lippman
The 0.148M suspension of n) was prepared by (a) maintaining a uniform iodide level in the growing silver halide crystals of 4.125M%, and (b) 0.1% silver iodobromide. 848
Until the moles were formed, pBr in the reactor was added proportionally (53.33 minutes, constant flow) to maintain the value obtained by the addition of KBr described above before the onset of nucleation and growth. Thereafter, 1M KBr was added to add excess Br ⁻
The concentration was adjusted and the addition was carried out until the pBr reached 2.20. Subsequently, 2.5M AgNO ₃ , 2.8M KBr
And the flow of 0.148M suspension of AgI (Lippmmann) was resumed (additional flow was accelerated, segment initial flow: segment final flow = 1: 12.6). Also, the addition was performed so that pBr in the reactor was maintained at 2.20.
0.14 of M KBr and AgI (Lippmann)
This was performed while adjusting the flow rate of the 8M suspension. As a result, a total of 19.5 mol (4.125 M% I) of silver iodobromide was produced. When the addition of AgNO ₃ , AgI and KBr was completed, the resulting emulsion was coagulated and washed, and the pH and pBr were adjusted to storage values of 6 and 2.5, respectively. The obtained emulsion was examined by the above-mentioned grain analysis method. 99.5 of total grain projected area
% Were tabular grains. The tabular grains had a (111) major surface. The average ECD of this emulsion is 1.88 μm and their COV is 32%
Met. The level of 1,1'-diethyl-2,2'-cyanine dye required for saturated coverage was determined and the solution absorption coefficient of this dye was 77,300 l / mol- ^cm , The equation for surface area was solved using the site area of 0.566 nm ² . The average thickness of the emulsion grains determined from the dye adsorption measurement was 0.140 μm.
m. The average silver bromide content was 95.9 mol%
Met.

<Emulsion B> (Comparative example of ultrathin tabular grains) In a vessel equipped with a stirrer, 3.75 g of lime-processed bone gelatin, 4.76 g of KBr, an antifoaming agent, and adjusted to pH 1.8 at 39 ° C. 6 liters of water, containing a sufficient amount of sulfuric acid to do so. AgNO ₃
Solution and halide (KBR and KI each 98.5
M% and 1.5 M%) solutions (both 2.5 M) in a quantity sufficient to produce 0.01335 moles of silver iodobromide during nucleation achieved by simultaneous addition. , PBr and pH were almost maintained at the values initially set in the solution in the reactor. Following nucleation, Oxone
(Trademark) (2KHSO ₅ · KHSO ₄ · K ₂ SO ₄ Ald
Rich) (128 g) was added to a solution prepared by dissolving 128 mg in water (20 ml) to rapidly oxidize gelatin in the reactor.
The temperature was raised to 54 ° C. for 9 minutes. After holding the reactor and its contents at this temperature for 9 minutes, a solution of 100 g of methionine oxidized lime-processed bone gelatin in 1.5 l of water was added to the reactor at 54 ° C. Next, the pH was raised to 5.90 and 122.5 ml of 1 M KBr was added to the reactor. 24.5 minutes after nucleation, the growth phase begins, during which 2.5M AgNO ₃ , 2.8M
0.148M of KBr and AgI (Lippmmann)
Suspending the suspension, (a) maintaining the iodide level in the growing silver halide crystals uniform at 4.125 M%;
And (b) until 0.848 moles of silver iodobromide are formed,
The pBr in the reactor was added proportionately (53.33 minutes, constant flow) to maintain the value obtained by the addition of KBr before the onset of nucleation and growth. afterwards,
The excess Br ^- concentration was increased by addition of a 1 M KBr solution and the addition was carried out until the pBr was 1.28. Subsequently, 2.5 M AgNO ₃ , 2.8 M KBr and Ag
The flow of the 0.148 M suspension of I (Lippmann) was resumed (additional flow was accelerated, segment initial flow: segment final flow = 1: 12.6). Further, the addition was performed so that the pBr in the reactor was maintained at 1.28, and 2.8 M KB was added.
This was performed while controlling the flow rate of the 0.148 M suspension of r and AgI (Lippmmann). As a result, a total of 9 mol (4.125 M% I) of silver iodobromide was produced. AgNO
_3. When the addition of AgI and KBr was completed, the resulting emulsion was coagulated and washed to adjust the pH and pBr to storage values of 6 and 2.5, respectively. The resulting emulsion was examined in the same manner as Emulsion A. Tabular grains accounted for more than 99.5% of total grain projected area. The tabular grains had a (111) major surface. The average ECD of the emulsion grains was 1.91 μm and their COV was 37%. Since tabular grains account for almost all of the grains present, the average grain thickness was measured using a dye adsorption method. The average thickness of the emulsion grains as determined by dye adsorption measurement in the same manner as described for Emulsion A was 0.063 μm. The average silver bromide content was 95.8 mol%.

<Emulsion C> (Thin Tabular Grains + Surface Reduction Sensitization Comparative Example) An emulsion E was prepared in the same manner as Emulsion A, except that the following changes were made.

After the formation of the particles, thiourea dioxide was added to 1 m of silver.
1 × 10 ⁻⁵ mol was added per ol.

<Emulsion D> (Thin tabular grains + surface reduction sensitization + addition of sodium thiosulfonate Comparative Example) Emulsion D was prepared in the same manner as Emulsion A, except that the following changes were made.

After the completion of the grain formation, thiourea dioxide was added to 1 m of silver.
1 × 10 ⁻⁵ mol per mol and sodium ethylthiosulfonate were added at 3 × 10 ⁻⁵ mol per mol of silver.

<Emulsion E> (Thin tabular grains + internal reduction sensitization Comparative Example) Emulsion E was prepared in the same manner as Emulsion A, except that the following changes were made.

After 24.5 minutes from the nucleation, 1 × 10 ⁻⁵ mol of thiourea dioxide was added per 1 mol of silver.

<Emulsion F> (Thin tabular grains + internal reduction sensitization + addition of sodium thiosulfonate Comparative Example) Emulsion F was prepared in the same manner as Emulsion A, except that the following changes were made.

After 24.5 minutes from the nucleation, 1 × 10 ⁻⁵ mol of thiourea dioxide was added per 1 mol of silver, and at the stage when 80% of the added silver was consumed, sodium ethylthiosulfonate was added at 3 × 10 ⁵ mol per 1 mol of silver. 10 ^-5 mol was added.

<Emulsion G> (Ultra-thin tabular grains + surface reduction sensitization Comparative Example) Emulsion B was prepared in the same manner as Emulsion B, except for the following changes.

After the completion of grain formation, thiourea dioxide was added to 1 m of silver.
1 × 10 ⁻⁵ mol was added per ol.

<Emulsion H> (Ultra-thin tabular grains + surface reduction sensitization + addition of sodium thiosulfonate Comparative Example) Emulsion H was prepared in the same manner as Emulsion B except that the following changes were made.

After the completion of grain formation, thiourea dioxide was added to 1 m of silver.
1 × 10 ⁻⁵ mol per mol and sodium ethylthiosulfonate were added at 3 × 10 ⁻⁵ mol per mol of silver.

<Emulsion I> (Ultra-thin tabular grains + internal reduction sensitization Comparative Example) Emulsion I was prepared in the same manner as Emulsion B except for the following changes.

24.5 minutes after the nucleation, 1 × 10 ⁻⁵ mol of thiourea dioxide was added per 1 mol of silver.

<Emulsion J> (Ultra-thin tabular grains + internal reduction sensitization 1 + addition of sodium thiosulfonate) This was prepared in the same manner as Emulsion B, except that the following changes were made.

After 24.5 minutes from the nucleation, 1 × 10 ⁻⁵ mol of thiourea dioxide was added per 1 mol of silver, and at the stage when 80% of the added silver was consumed, sodium ethylthiosulfonate was added at 3 × 10 ⁵ mol per 1 mol of silver. 10 ^-5 mol was added.

<Emulsion K> (Ultra-thin tabular grains + internal reduction sensitization 2 + addition of sodium thiosulfonate) This was prepared in the same manner as Emulsion B, except that the following changes were made.

After 24.5 minutes from the nucleation, 5 × 10 ⁻⁶ mol of thiourea dioxide was added per 1 mol of silver, and at the stage when 80% of the added silver was consumed, sodium ethylthiosulfonate was added at 3 × 10 ⁻⁶ mol per mol of silver. 10 ^-5 mol was added.

<Emulsion L> (Ultra-thin tabular grains + internal reduction sensitization 1 + addition of sodium thiosulfonate) In the present invention, emulsion E was prepared in the same manner as emulsion B except that the following changes were made.

24.5 minutes after the nucleation, 1 × 10 ⁻⁵ mol of thiourea dioxide was added per 1 mol of silver, and at the stage when 80% of the added silver was consumed, sodium benzenethiosulfonate was added at 3 × 10 ⁵ mol per 1 mol of silver. 10 ^-5 mol was added.

<Emulsion M> (Ultra-thin tabular grains + internal reduction sensitization 2 + addition of sodium thiosulfonate) In the present invention, emulsion E was prepared in the same manner as in emulsion B except that the following changes were made.

24.5 minutes after the nucleation, thiourea dioxide was added in an amount of 5 × 10 ⁻⁶ mol per mol of silver, and sodium benzenethiosulfonate was added in an amount of 3 × 10 ⁶ mol per mol of silver at the stage when 80% of the added silver was consumed. 10 ^-5 mol was added.

The average equivalent circle diameter and average thickness of the above emulsions C to M were determined in the same manner as for emulsion A. The measurement results are shown in Table 2.

<Sensitization step> Next, each of the emulsions A to M obtained as described above was subjected to the following sensitization.

0.5 mol of each emulsion was melted at 40 ° C.
By simultaneously adding the NO ₃ solution and the KI solution, pBr
Was adjusted to about 4. At this time, the AgNO ₃ solution and the KI solution contained 12% of silver halide precipitated in a small amount during this preparation.
AgI was added in such a ratio as to be AgI. Next, spectral sensitizing dyes 1 and 2 were added at a ratio of 1: 1 so that the total coverage was about 70%. Thereafter, potassium thiocyanate, sodium thiosulfate and potassium chloroaurate were added to perform optimal chemical sensitization, and then 4-hydroxy-6-methyl-1,
3,3a, 7-Tetraazaindene (TAI) and 1-phenyl-5-mercaptotetrazole (PMT) were added. After all the components were added, the mixture was heated to 60 ° C. to complete the sensitization, and after cooling, more PMT was added.

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<Preparation of Single Layer Photosensitive Material> Each of the sensitized emulsions A to M was applied to a cellulose acetate film support coated with a gray silver antihalation layer, and the emulsion layer was coated with a surfactant and bismuth. It was overcoated with a 4.3 g / m ² gelatin layer containing (vinylsulfonyl) methane hardener (1.75% by weight based on total weight of gelatin).
The emulsion coverage was 0.646 gAg / m ² , and this layer also contained couplers 1 and 2, a surfactant, and a total of 1.08 g / m ^{2 of} gelatin. Thus, the samples 101 to 1 of the single-layer light-sensitive material were respectively applied to the emulsions A to M
13 was obtained.

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Samples 101 to 11 thus obtained
3 were each exposed to a wedge for 0.01 second with white light,
Color development was performed according to the following processing steps.

Processing steps

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[Table 1]

The following were used for color development, bleaching solution, fixing solution and stabilizing solution.

(Color development) Water 800 ml Potassium carbonate 30 g Sodium hydrogen carbonate 2.5 g Potassium sulfite 3.0 g Sodium bromide 1.3 g Potassium iodide 1.2 mg Hydroxylamine sulfate 2.5 g Sodium chloride 0.6 g 4-amino -3-Methyl-N-ethyl-N- (β-hydroxylethyl) aniline sulfate 4.5 g Diethylenetriaminepentaacetic acid 3.0 g Potassium hydroxide 1.2 g Add water to make 1 liter, and add potassium hydroxide or 20%
Adjust to pH 10.06 with sulfuric acid.

(Bleaching solution) Water 700 ml 1,3 Diaminopropanetetraacetate iron (III) ammonium 125 g ethylenediaminetetraacetic acid 2.0 g sodium nitrate 40 g ammonium bromide 150 g glacial acetic acid 40 g Add water to make 1 liter, and add ammonia water or ice Adjust to pH 4.4 with acetic acid.

(Fixing solution) Water 800 ml Ammonium thiocyanate 120 g Ammonium thiosulfate 150 g Sodium sulfite 15 g Ethylenediaminetetraacetic acid 2 g Water is added to make 1 liter, and the pH is adjusted to 6.2 using aqueous ammonia or glacial acetic acid.

(Stabilizing solution) Water 900 ml Dimethylolurea 0.5 g Hexamethylenetetramine 0.2 g 1,2-Benzisothiazolin-3-one 0.1 g Siloxane (UCC L-77) 0.1 g Ammonia water 0.5 ml

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Water is added to 1 liter, and the pH is adjusted to 8.5 using aqueous ammonia or 50% sulfuric acid.

Thereafter, an optical densitometer (PDA-6 manufactured by Konica) was used.
5) was used to measure the sensitivity and fog.

(Evaluation) -Sensitivity- Fog was expressed as a relative value of the logarithm of the reciprocal of the exposure amount E (E is expressed in units of lux seconds) giving a density of +0.2.

-Fog- Fog was represented by the absolute optical density of the unexposed area.

-Sharpness- The sharpness was determined by the MTF (Modulation Transfer Function) method. For more information on this, see "Photochemistry"
(Photo Industry Publishing Co., Akira Sasai) pp. 430-437. The MTF chart was exposed and developed with white light, and the MTF value at 15 cycles / mm was measured.

Table 2 shows the relative sensitivity, fog, and MTF value when the sensitivity of Sample 101 was set to 100.

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[Table 2]

*: Thiosulfonic acid derivative As is clear from the results in Table 2, in the case of blue recording, Sample 11 using ultrathin tabular grains (Emulsions J to M) of the present invention was used.
The sensitivity, fogging and sharpness of Dramatically improved sensitization, fogging and sharpness were significantly improved in the case of 0 to 113 (addition of sodium thiosulfonate represented by the general formula for internal reduction sensitization). It can be seen that the reduction-sensitized silver halide-containing emulsion is significantly deteriorated in fog. In general,
According to the present invention, an emulsion having high sensitivity, low fog and high sharpness can be obtained.

Example 2 Emulsions N and O were prepared as follows.

<Emulsion N> (Ultra-thin tabular grains + Internal reduction sensitization 1 + Addition of sodium thiosulfonate + Metal doping) Emulsion N was prepared in the same manner as Emulsion J, except for the following changes.

24.5 minutes after nucleation, K ₄ Ru (C
N) ₆ was added at 1 × 10 ⁻⁴ mol per mol of silver.

<Emulsion O> (Ultra-thin tabular grains + internal reduction sensitization 1 + addition of sodium thiosulfonate + metal doping In the present invention) Emulsion O was prepared in the same manner as Emulsion J, except for the following changes.

24.5 minutes after nucleation, K ₄ Fe (C
N) ₆ was added at 1 × 10 ⁻⁴ mol per mol of silver.

<Sensitization, Preparation of Sample of Single Layer Photosensitive Material and Its Evaluation> Emulsions N and O obtained as described above were sensitized in the same manner as in Example 1, and a single layer photosensitive material was prepared. And samples 21 and 22 were obtained. With respect to the samples 21 and 22 thus obtained, the sensitivity,
Fog and sharpness (MTF value) were measured. Table 3 shows the relative sensitivity, fog, and MTF value when the sensitivity of the sample 110 manufactured in Example 1 was set to 100.

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[Table 3]

*: Thiosulfonic acid derivative As is apparent from Table 3, ultrathin tabular grains to which sodium thiosulfonate represented by the general formula was added for internal reduction sensitization were further doped with a metal according to the present invention. Sample 2
It can be seen that Nos. 1 and 22 achieve high sensitivity without deteriorating fog and sharpness. As described above, by performing metal doping, it is possible to obtain an emulsion having high sensitivity, low fog, and high sharpness, which has not been achieved in the past.

Example 3 <Emulsions PS> The above emulsions J, L, N, and O were sensitized including silver salt epitaxial as shown below to obtain emulsions PS.

(Epitaxial Sensitization) 0.5 mol of each emulsion was melted at 40 ° C., and pBr was adjusted to about 4 by simultaneously adding an AgNO ₃ solution and a KI solution. At this time,
The AgNO ₃ solution and the KI solution were added at a ratio such that the silver halide that precipitated in small amounts during this preparation was 12% AgI. Next, after addition of 2M% NaCl (based on the initial amount of silver iodobromide host), spectral sensitizing dyes 1 and 2 were added in a 1: 1 ratio so that the total coverage was about 70%. Thereafter, 6M% AgCl epitaxy was formed by double jet addition, which balanced the AgNO ₃ solution and the NaCl solution. This operation resulted in epitaxy growth mainly at the corners and edges of the host tabular grains. Subsequently, spectral sensitizing dyes 1 and 2 were added for optimal spectral sensitization. Thereafter, as in Example 1, potassium thiocyanate, sodium thiosulfate, and potassium chloroaurate were added to perform optimal chemical sensitization, and then the above TA
I and PMT were added. After all the components have been added, the mixture is heated to 60 ° C. to complete the sensitization, and after cooling,
T was added.

<Preparation of Sample of Single Layer Photosensitive Material and Its Evaluation>
Next, samples of the single-layer light-sensitive material were prepared in the same manner as in Example 1 using the emulsions P to S subjected to the epitaxial sensitization, and samples 31 to 34 were obtained for the emulsions P to S, respectively. .

For the samples 31 to 34 thus obtained, the sensitivity, fog and sharpness (M
TF value) was measured. Table 4 below shows the relative sensitivity, fog, and MTF value of the sample 110 manufactured in Example 1 assuming that the sensitivity is 100.

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[Table 4]

*: Thiosulfonic acid derivative As can be seen from Table 4, the emulsion of the present invention is sharpened by subjecting ultrathin tabular grains to which sodium thiosulfonate is added for internal reduction sensitization to sensitization including epitaxial growth. Although the degree is slightly deteriorated, it is found that the sensitivity is remarkably increased without deteriorating the fog, whereby it is possible to obtain an emulsion having a high sensitivity, low fog, and high sharpness which has not been obtained conventionally.

Embodiment 4 Next, an embodiment in which the present invention is applied to minus blue recording will be described.

In the sensitizing step of Example 1, the spectral sensitizing dyes were changed to the following 3 to 5 and the spectral sensitizing dyes 3 to 5 were changed.
Was added at a ratio of 1: 1: 1 so that the total coverage was about 70%, and the couplers were changed to couplers 3 and 4 shown below in the preparation of a single-layer light-sensitive material. The emulsion obtained in the same manner was sensitized to obtain samples 401 to 413 of single-layered light-sensitive materials, which were similarly processed (however, the color development time was 2 minutes and 50 seconds) and evaluated. Table 5 shows the obtained results.

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[Table 5]

*: Thiosulfonic acid derivative As is apparent from Table 5, the same improvement effect as in the case of blue recording was confirmed when the emulsion of the present invention was applied to minus blue recording.

Example 5 In the sensitization step of Example 2, the spectral sensitizing dyes were changed to the above-mentioned spectral sensitizing dyes 3 to 5, and the total coverage of the spectral sensitizing dyes 3 to 5 became about 70%. As described above, the emulsion was added in the ratio of 1: 1: 1, and the emulsion was obtained in the same manner as in Example 2 except that the couplers were changed to the above couplers 3 and 4 in the preparation of a sample of a single-layer photosensitive material. Sensation, samples 51 to 52 of the single-layer photosensitive material
And processed in the same way (however, the color development time is 2 minutes and 50 seconds)
And evaluation. Table 6 shows the obtained results.

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[Table 6]

*: Thiosulfonic acid derivative As is clear from Table 6, when the emulsion of the present invention was applied to minus blue recording, the same improvement effect as in blue recording was confirmed.

Example 6 In the sensitization step of Example 3, the spectral sensitizing dye was changed to the above-mentioned spectral sensitizing dyes 3 to 5, and the total coverage of the spectral sensitizing dyes 3 to 5 became about 70%. 1: 1: 1 as described above, and using the emulsion obtained in the same manner as in Example 3 except that the couplers were changed to the above couplers 3 and 4 in the preparation of a sample of a single layer photosensitive material. Sensation, and samples 61 to 64 of single-layer photosensitive material
And processed in the same way (however, the color development time is 2 minutes and 50 seconds)
And evaluation. Table 7 shows the obtained results.

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[Table 7]

*: Thiosulfonic acid derivative As is clear from Table 7, even when the emulsion of the present invention was applied to minus blue recording, the same improvement effect as in the case of blue recording was confirmed.

The same effect was obtained when these ultrathin tabular grains of the present invention were applied to a multilayer photographic light-sensitive material.

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According to the present invention, an extremely thin tabular silver halide photographic emulsion having high sensitivity, low fog and excellent sharpness can be obtained even in blue recording and minus blue recording.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI G03C 1/09 G03C 1/09

Claims (4)

[Claims] 1. A flat plate having a (111) main surface, an average silver bromide content of 70 mol% or more, an average equivalent circle diameter of 0.7 μm or more, and an average grain thickness of less than 0.07 μm. A silver halide emulsion in which silver halide grains occupy 90% or more of the total projected area, wherein reduction sensitization is performed inside the tabular silver halide grains during the production process, and the following general formula (1) A) a silver halide emulsion, which is an emulsion to which at least one selected from the compounds represented by (3) is added. Formula _{(1) R-SO 2 S} -M (2) R-SO 2 S-R 1 (3) in _{R-SO 2 S-L m} -SSO 2 -R 2 ( wherein, R, R _1, R ₂ is an aliphatic group, alicyclic (remaining compound)
Represents an aromatic group or a heterocyclic group, which may be the same or different, and M represents a cation. L represents a divalent linking group, and m is 0 or 1. The compounds of the above general formulas (1) to (3) may be polymers containing, as a repeating unit, a divalent group derived from the structure shown in the above (1) to (3). When possible, R, R ₁ , R ₂ , L
May combine with each other to form a ring. ) 2. The silver halide emulsion according to claim 1, wherein said tabular silver halide grains contain a dopant. 3. The silver halide grain has a latent image forming chemical sensitized site on its surface, and the site includes at least one type of silver halide projection portion epitaxially arranged. 3. The silver halide emulsion according to 1 or 2. 4. A photographic light-sensitive material comprising the silver halide emulsion according to claim 1.