JP2835607B2 - Silver halide emulsion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silver halide (hereinafter referred to as AgX) emulsion which is useful in the field of photography, and more particularly to a dispersion medium and a substantially flat main plane as shown in FIG. And an AgX emulsion composed of surface layers having twin planes parallel to each other and having regions having different iodine contents from each other.

[0002]

2. Description of the Related Art Lithographic AgX emulsion grains having parallel twin planes have many advantages described in JP-A-2-838 and, depending on the purpose, have an aspect ratio of 1 or more, and usually have an aspect ratio of 1 or more. Also has the advantage that it can be changed freely in the region from 1 to 20. However, since the specific surface area of the particles is large, the latent image tends to be dispersed particularly when the particle size is large. Therefore, in order to achieve high sensitivity and high image quality, it is necessary to limit the positions of chemical sensitization nuclei of the tabular grains and the unit area per unit area. Regarding the limiting method, see Japanese Patent Laid-Open No. 2-838 by the present inventor.
And 2-146033.

[0003]

SUMMARY OF THE INVENTION The present invention relates to each of Ag
It is an object of the present invention to provide AgX milk silver which has solved the above-mentioned problems by using AgX grains having an AgX layer having regions having different halogen compositions on the X grain surface. The present invention particularly uses AgX grains which are parallel twinning silver halide grains whose aspect ratio can be freely changed and which can easily control the position of chemical sensitization nuclei and the number per unit area. Accordingly, an object of the present invention is to provide an AgX emulsion capable of improving sensitivity, image quality, development progress, and the like.

[0004]

According to the present invention, silver halide grains containing at least a dispersion medium and silver halide grains and having an amount corresponding to 30% or more of the projected area of all silver halide grains are provided. A silver halide emulsion having twin planes parallel to each other and whose main plane is a substantially flat grain, wherein the silver halide grains having the twin plane are exposed on the main plane. A high iodine content surface layer having the following formula: and a iodine content lower than the high iodine content surface layer formed around the main plane of the high iodine content surface layer by 3 mol% or more. A silver iodide emulsion comprising a low iodine content surface layer, and wherein a chemical sensitization nucleus is preferentially formed on the low iodine content surface layer.

[0005] Preferred embodiments of the present invention are described below. (1) The ratio of the surface area of the high iodine content surface layer to the area of the low iodine content surface layer exposed on the main plane in the silver halide grains having the twin plane is 1/3 to 35. / 1
(Area of high iodine content surface layer surface / low iodine content surface layer surface area). (2) In the silver halide grains having twin planes, the number of chemical sensitization nuclei preferentially formed on the low iodine content surface layer per unit area is high iodine content surface layer. More than twice (especially more than 5 times) the number of the chemical sensitization nuclei formed on the unit area per unit area.

(3) The projected area of all silver halide grains is 6
Silver halide grains having an amount corresponding to 0% or more (particularly 90% or more) are silver halide grains having the twin plane described above. (4) The silver halide grains having twin planes are monodisperse parallel double twin grains having an aspect ratio in the range of 3 to 20 and a variation coefficient of 20% or less, and The iodine content of the low iodine content surface layer is higher than the iodine content of the low iodine content surface layer at a mol% in the range of 7 to 35 mol%,
Further, the cyanine dye is preferentially adsorbed on the high iodine content surface layer.

First, the structure of the silver halide grains of the present invention will be described in detail, and then the method for producing the silver halide emulsion of the present invention will be described in detail.

[Structure of the AgX Particles of the Present Invention]
The gX particles are AgX particles (parallel double twin particles) having two or more, preferably two, twin planes parallel to each other in each AgX particle. Although parallel double twin particles and parallel triple twin particles may be mixed, it is preferable that the parallel double twin particles occupy 70% or more in the projected area ratio. This is because the tabular grain ratio can be made higher and the size distribution can be made narrower. In this regard, the descriptions in JP-A-63-151618 and JP-A-2-838 can be referred to.

The number of twin planes of AgX grains can be determined by subjecting an ultra-thin layer (up to 0.1 μm thick) section of a section of the AgX emulsion-coated film to TE at a low temperature (liquid nitrogen temperature or liquid He temperature).
It can be confirmed by observing an M image (a transmission electron micrograph image). In this regard, D.A. L. B
luck, etc., The InternationalEa
st West Symposium II, Proceedings,
The description of C-71 (1988) can be referred to. In addition, the number of twin planes can be determined from the shape of AgX particles. That is, the shape of the main plane of the parallel double twin particles is a hexagon with a maximum adjacent side ratio ≦ 2.
Here, the maximum adjacent side ratio indicates a ratio of sides forming a hexagon in one hexagonal tabular grain (maximum side length / minimum side length). On the other hand, the shape of the main plane of the parallel triple twin particles is a triangle. Regarding the relationship between the number of twin planes and the particle shape,
J. E. FIG. Maskasky, J. et al. Imaging Sc
i. , 31 , 15-26 (1987).

As shown in FIG. 1, the AgX particles of the present invention have two or more surface layers (inner (core portions)) having substantially flat main planes and regions having different iodine contents.
And a low iodine content surface layer formed on the periphery (shell portion) in the plane direction of the low iodine content surface layer. Is defined as having an iodine content of 7 mol% or less, preferably 4 mol% or less, and a chlorine content of preferably 60 mol% or less, more preferably 30 mol%.
Refers to a layer having the following composition (eg, AgBrClI) and having a surface exposed in the main plane. On the other hand, the high iodine content surface layer is defined as having an iodine content of 4 mol% to the solid solution limit, preferably 7 to 35 mol%, and a chlorine content of 10 mol% or less, preferably 3 mol% or less. Refers to a layer having a composition (eg, AgBrClI) and having a surface exposed in a main plane. In the same AgX particles, the difference in iodine content between the low iodine content surface layer and the high iodine content surface layer is 3 mol% or more, preferably 7 to 35 mol%. The surface layer referred to in the present invention preferably refers to a surface layer having 10 to 100 lattice layers, particularly preferably 50 to 100 lattice layers.

The specific cross-sectional structure and top view of the AgX particles of the present invention are shown in the schematic diagram of FIG.

FIG. 1 is a sectional structural view of a silver halide grain of the present invention in which the surface layer of the core is a high iodine content layer. The core portion may be a high iodine content surface layer (shaded portion) as shown in FIG. 1 (a), and the low iodine content center as shown in FIG. 1 (b). The portion may be wrapped in a high iodine content layer (hatched portion), and as shown in FIG. 1 (c), further outside (in the plane direction) of the particles having the structure of FIG. A structure provided with a high iodine content layer may be used. When the structure shown in FIG. 1A is taken as an example, the structure shown in FIG. 1D or the structure shown in FIG. In terms of the manufacturing process, there is an advantage that particles having the structure shown in FIG. 1A can be prepared most easily.

The grain structure of the silver halide grains of the present invention is as follows:
A part of the core emulsion was sampled, the average thickness of the grains was observed in a TEM image, and then the average thickness after growing the core emulsion grains was measured. Can be confirmed by checking. In addition, an analysis method (Elect by scanning with a finely focused electron beam and observing characteristic X-rays and the like generated from particles by the scanning)
ron ProbeMicroanalysis (EP
MA) method and analytical electron microscopy]. About this method, Inoue: Konica
Tech. Report, Vol. 2, p. 116 (1989)
), Photographic Society of Japan, 46
987).

The halogen composition change between the high iodine content surface layer and the low iodine content surface layer may be of an increasing type or a steep type, and can be arbitrarily selected according to each purpose. That is, when the steep type is used, the effect as described in JP-A-63-220238 can be obtained, and in the case of a gradual change, particles having few electron trapping defects can be obtained. These are disclosed in JP-A-63-92942 and JP-A-59-4543.
No. 8, No. 61-245151, and No. 60
The description in JP-A-143331 can be referred to.

The AgX particles of the present invention are, as shown in FIG.
The main plane is composed of surface layers having different iodine contents from each other, and further characterized in that the chemical sensitization nuclei are preferentially formed on the surface of the surface layer on the lower iodine content side, In this case, the priority means the ratio of the number of sensitization nuclei per unit area (the number of chemical sensitization nuclei on the crystal surface on which the chemical sensitization nuclei are preferentially formed /
cm ² ) / (the number of chemical sensitization nuclei on the crystal surface where no chemical sensitization nuclei are preferentially formed / cm ² ) is preferably 2 or more,
Particularly preferably, it means the case of 5 or more. It is difficult to observe this ratio directly. However, exposure [1 second exposure. The amount of exposure was the same as that of MAA-
An exposure amount that gives a density of (maximum density−minimum density) × １ ／ when developed with one developing solution at 20 ° C. for 10 minutes is set to an exposure amount of 10 times the exposure amount. If the exposure amount is less than this, the number of particles having no suppressed development nuclei increases, which makes measurement difficult. Then, a latent image is formed on the chemically sensitized nucleus (photosensitive nucleus), suppressed development is performed, the suppressed development nucleus is made visible by electron microscope observation, and the number of the suppressed development nucleus is counted. The above ratio of the chemical sensitizing nucleus can be determined. For this approach, see D.S. C. Birch et al., Jo
urnal of Photographic Sci
ence, 23, 249-256 (1975),
This is described in JP-A-64-62631. Here, the chemical sensitizing nucleus is a chemical sensitizing nucleus composed of sulfur, selenium, tellurium, gold and a Group 8 noble metal compound alone or in combination, most preferably (gold-sulfur and / or selenium sensitizing nucleus). It is. Usually sulfur sensitizing nuclei,
It is referred to as a gold sensitizing nucleus, a noble metal sensitizing nucleus or a combination thereof, and the details can be referred to the following literature.

In a further preferred embodiment of the present invention, the region where the chemical sensitization nuclei are formed is limited as described above, and the number of chemical sensitization nuclei per unit area in each of the chemical sensitization generation regions (priority generation regions). (The number of chemical sensitization nuclei / cm ² ) can also be limited.

As shown in FIG. 1, the A of the present invention
The chemical sensitization nucleus (b) of gX grains is preferentially formed on the low iodine content crystal surface layer. This is because usually, when a latent image is formed on a low iodine content surface layer, the initial developing speed is higher, and the developing process can be performed more quickly. More preferably, the cyanine dye (c) for spectral sensitization is preferentially adsorbed on the high iodine content surface layer. This is because the latent image forming site and the color sensitizing site are separated, and the effects described in Japanese Patent Application No. 63-251215 can be obtained in the light absorbing process, the latent image forming process, and the developing process.

In the present invention, the chemical sensitization nucleus is preferentially formed on the low iodine content surface layer, and its ratio (surface area of high iodine content surface layer / low iodine content) (Surface area of the surface layer) is preferably 1/3 or more, more preferably 1/1 to 35/1. If it is smaller than 1/3, the effect of the present invention is reduced, which is not preferable. When it becomes larger than 35/1,
The production region of the chemical sensitization nucleus is too small and limited,
It is not preferable because the electron capture cross section becomes too small during the exposure process.

The aspect ratio of the AgX particles of the present invention is 1 or more, preferably 3 to 20. Here, the aspect ratio is an average ratio represented by (diameter of tabular grains) / (thickness of tabular grains). Further, the diameter of a particle means the diameter of a circle having an area equal to the projected area of the particle when the particle is observed with an optical microscope or an electron microscope. When the aspect ratio is smaller than 3, the characteristics of tabular grains are reduced, and when the aspect ratio is 20 or more, the monodispersity is deteriorated.

The average halogen composition of the whole AgX particles of the present invention is AgBrClI, the Cl ^- content is preferably 10 mol% or less, more preferably 3 mol% or less, and the I ^- content is preferably 2 mol% or less. % To the solid solution limit, more preferably 5 to 30 mol%. Incidentally, Cl ^- content: and I
^- once the content:, Br ^- content: is determined automatically.

The diameter of the AgX particles of the present invention is 0.2 μm.
m, preferably 0.3 to 5 μm.

The particle size distribution of the AgX particles of the present invention is preferably monodisperse. The monodispersity as used herein is represented by a mobility coefficient [a value obtained by dividing a variation (standard deviation) of a grain size represented by a circle-converted diameter of a projected area of the tabular grain by an average grain size]. The monodispersity of the AgX particles of the present invention is preferably 35% or less, more preferably 20% or less, most preferably 15% or less in terms of variation coefficient.

The main plane of the tabular AgX grains of the present invention is substantially flat, but substantially means that the depression on the main plane is 49 lattices or less, preferably 40 lattices or less, more preferably 20 lattices or less. It indicates that the size is equal to or less than the lattice, and more preferably equal to or less than 10 lattices. That is, in FIG. 1, the number of dents in the high iodine content surface layer and the low iodine content surface layer is smaller than 50 lattices. The AgX particles of the present invention are described in
It is different from the AgX particles described in JP-A-3-31244.
The AgX particles described in the publication introduce defects (depths of 50 lattices or more, preferably 300 lattices or more) such as etch pits and depressions at the center of the tabular particles, and use the defects to form latent images. Although mainly intended to be concentrated at the center of the tabular grains, the AgX grains of the present invention are not intended to utilize the defects.

It is preferable that the grains contain reduction sensitized silver nuclei. The presence or absence of this reduction sensitized silver nucleus can be easily determined by exposing, internally developing by an ordinary method, and drawing an HD curve, since a reversal image of the existing internal fog is observed. You can judge. For details, the description in JP-A-2-14633 can be referred to.

Next, a method for producing the AgX emulsion of the present invention will be described.

[AgX Emulsion Method of the Present Invention] (A) AgX Emulsion Method The AgX particles of the present invention basically form core particles by (nucleation → ripening) or (nucleation → ripening → growth). ,
Next, the particles can be manufactured by forming a shell layer by growing crystals only in a direction parallel to the twin plane. The following literature can be referred to for the production method of such core particles. That is, with respect to the conventional method for forming tabular grains having two or more parallel twin planes, JP-A-58-113926 and 58-113
References can be made to the descriptions of the references cited in 3926, 58-113928 and JP-A-63-151618.

With respect to the method for producing silver halide grains having only two twin planes parallel to each other and having a high iodine content AgBrI layer at the center, see Japanese Patent Application No. 1-90089 by the present inventor. JP-A-2-28638) can be referred to. Briefly, the nucleation is carried out by adding an aqueous solution of a silver salt and an aqueous solution of a halide salt while maintaining the pBr at 1 to 2.5 in an aqueous solution containing a dispersion medium. The frequency of twin plane formation during nucleation is
Various gelatin concentration at the time of supersaturation factors [nucleation, the type of gelatin, the addition rate of the aqueous silver salt solution and a halide salt aqueous solution, Br in the reaction solution ^-, Cl -, I ^- concentration, stirring rotational speed, the halide to be added I ^- content in aqueous salt solution, Ag
X solvent concentration, temperature, pH, unrelated salt concentration, etc.]
The dependence is shown in the drawing of JP-A-63-93942. If the twin plane formation probability is too high, the abundance ratio of nontabular grains in the finally obtained AgX emulsion will increase. Therefore, the supersaturation factor may be adjusted so as to eventually increase the tabular grain ratio while observing the dependence of these figures.

Gelatin is preferably used as a dispersion medium at the time of nucleation. Modified gelatin such as phthalated gelatin can be used in addition to alkali-treated gelatin and acid-treated gelatin. As the molecular weight of gelatin, low molecular gelatin (molecular weight of 2,000 to 100,000) can be preferably used in addition to gelatin having an average molecular weight of M = 100,000 usually used in the photographic industry. Other conditions at the time of nucleation and subsequent ripening conditions can be referred to the description in the above-mentioned literature. In the aging process, the non-tabular grains disappear,
By leaving the tabular grains, core emulsion grains having a high tabular grain ratio can be obtained.

At the stage of completion of the ripening, core grains having a high iodine content can be obtained. In general, a parallel twin plane is formed by further adding a silver salt aqueous solution and a halide salt aqueous solution to the emulsion. Parallel direction, direction perpendicular to the parallel twin plane,
Or grow in both directions, the intended particle size,
Core particles having an aspect ratio and a halogen composition are formed. The following description can be referred to for that.

Normally, when the tabular grains are grown under a Br ⁻ concentration of a cubic crystal or a tetradecahedral region close to cubic,
When selectively grown in the direction perpendicular to the parallel twin plane and grown under the Br ^- concentration in the octahedral or tabular grain formation region, the crystal is selectively grown in the direction parallel to the parallel twin plane. When grown under a Br ^- concentration intermediate between the two, growth occurs in both directions. However, the Br ^- concentration region in which cubic or octahedral crystals are formed depends on the pH, supersaturation, stirring level, amount of coexisting AgX solvent, halogen composition, and the like during crystal growth. These methods are described in Murofushi et al., Int
electronic Congress of Ph
otographic Science, Tokyo
(1967); Rodgers, Simposi
um paper on Growth of Pho
tosensitive Crystals, Cumb
Ridge (1978), T.W. G. FIG. Bogg et al.
Photo. Sci. , 24 , 81 (1984) and Japanese Patent Application Laid-Open No. 1-158425, can be practically confirmed by the following method.

First, the average thickness and average particle size of the core tabular grains are determined from the TEM image.
^- grown under concentration, the average thickness of the tabular grains after growth and average particle size determined from the TEM images. And selectively grown in the direction perpendicular to the parallel twin planes by comparing both Br ^- concentration region, Br selectively grown in the direction parallel to the parallel twin planes ^- density region, Br to grow in both directions ^- it is possible to check the density region. For example, if the core particle is Ag
Br, wherein AgX to be laminated on the particles is AgBr
_{When 0.9} I _0.1 , silver potential (vs. saturated calomel electrode)
C. at -60 to 0 mV. D. J. (Controlled
When it is grown by double jet addition, it grows selectively in the direction parallel to the parallel twin plane, while it grows in the range of 70 to 12
When grown at 0 mV, it grows in both directions. Also, 15
When grown at 0 mV, it grows selectively in the vertical direction.

On the other hand, when AgBr is laminated on AgBr core particles, it grows selectively in the direction parallel to the parallel twin plane at -60 to -20 mV, grows in both directions at 0 to +40 mV, and grows in both directions at 0 to +40 mV. It grows selectively in the vertical direction. However, the temperature is 75 ° C. and the pH is 6-9.

Further, AgBrCl is applied on the AgBr core particles.
Case of laminating the excess reaction solution X ^- is Br ^-
Without using, Cl ^- also selectively grown vertically when grown with.

However, the above crystal growth characteristics also depend on the degree of supersaturation during crystal growth. Normally, C.I. D.
J. When added, the higher the degree of supersaturation, the greater the proportion of vertical growth. This dependence is large when the central portion in FIG. 1 is of the AgBrI type having a high iodine content, particularly for small tabular grains having a diameter of 0.5 μm or less.

Regarding the relationship between silver potential and Br ^- concentration, see T.S.
H. James, The Theory Photog
raphic Process, Fourth Edi
tion, Chap. 1, Macmillan, New
The description in York, 1977 can be referred to.

In these cases, a more preferable method of adding a silver salt solute is to add a silver salt solute having a diameter of 0.1 having substantially no multiple twin planes.
AgX of 15 μm or less, more preferably 0.1 μm or less
A method of adding a fine grain emulsion can be mentioned. In this case, the AgX fine particles may be formed and added immediately before the addition, or AgX fine particles prepared in advance may be added. As a method for preparing the fine particles immediately before, as described in JP-A-1-183417, in addition to a method of continuously adding the fine particles while forming the fine particles,
As described in JP-A No. 5 (1993) -105, a method of adding fine particles in a batch system immediately before addition is effective. A method for preparing the AgX fine particles having substantially no multiple twin planes is disclosed in JP-A No. 2-14.
No. 6033 can be referred to. Briefly, the T of the finally obtained AgX particle replica is
Obtaining the conditions at the time of the formation of the parallel twin grains by observing an EM image in a direction in which the twin planes are not formed to form nuclei, and then growing the crystals in a normal crystal growth region. Can be. Here, "having substantially no multiple twin planes" means that the ratio of the number of particles having multiple twins is 7% or less, preferably 1% or less. In addition, “multiple” refers to double or more.

The advantages of the method of adding an aqueous solution of AgNO ₃ and an aqueous solution of an alkali halide salt (hereinafter referred to as an ion addition method) to the case where the stirring efficiency is not good are as follows. In order to increase the selective growth in the direction parallel to the parallel twin plane, the Br ^- concentration in the
When r is increased to about 5 g / L or more, the critical growth rate of the seed crystal tabular grains decreases in the ion addition method. Fast growing thin tabular grains are likely to be generated as new nuclei. The growth of the seed crystal tabular grains becomes non-uniform, and the grain size distribution broadens.
It has the disadvantage that growth in the direction perpendicular to the parallel twin planes also begins to occur. This is because the AgX particles constantly generated at the location where the AgNO ₃ aqueous solution is added become thin tabular grains having a high growth rate, so that the critical growth rate is reduced and the supersaturation of the growth system is reduced. However, it is considered that the solubility of AgX in the system is high (that is, the concentration of the AgBr _n- ^(n-1) complex is high), which results in low supersaturation growth under high solubility conditions and growth accompanied by Ostwald ripening. Can be On the other hand, when the AgX fine particle addition method was examined in the KBr 3 to 50 g / L region, the critical growth rate of the seed crystal tabular grains increased with the Br ⁻ concentration, which showed a good correlation with the solubility curve of AgX. In each of the critical regions, selective growth was observed only in the parallel twin plane direction, and uniform growth was observed between the grains. Therefore, emulsion grains of the present invention having good monodispersity were obtained. As a method for adding the fine grain emulsion, the fine grain emulsion can be added continuously or intermittently. However, if the addition amount is too large, ripening occurs between the fine particles, which is not preferable because the efficiency of disappearing the fine particles deteriorates. More preferably, the added fine particles disappear in 30 minutes or less,
More preferably, it disappears in 15 minutes or less. In this case, the preferred growth pBr region is pBr 1.8 to 0.3, more preferably 1.6 to 0.4. However, if the aging is continued after the fine particles have disappeared, the particle size distribution tends to widen, so it is preferable to immediately lower the temperature and wash with water.

In the case of the ion addition method, Japanese Patent Application No. Hei.
678 (see JP-A-3-21339) is effective. By using this apparatus, uniform addition is performed, and more selective growth is obtained.

JP-A-58-113927 discloses a particle having a low iodine content in a central region and a high iodine content in a region which is displaced in a lateral direction. For example, the iodide concentration can be increased near the major faces of the tabular grains and is usually configured as such. " It can be understood that tabular silver halide grains having the cross-sectional structure shown in the figure are generated. It states that "the iodide concentration in the central region and the region displaced laterally indicates the average concentration in these regions". Therefore, these grains are not surface-separated, and their structures are clearly different from the silver halide grains of the present invention.

By utilizing the growth characteristics of such tabular grains, tabular AgX grains having the structure shown in FIG. 1 and having a desired grain size, aspect ratio, and halogen composition can be formed. In this case, Br ^- is adsorbed on the surface of the tabular grains and acts as a kind of crystal growth controlling agent. Accordingly, Br ^- it is also effective to use an effective crystal growth control agent other than [mainly particles of (111) adsorbent which selectively adsorbs on the surface]. Further, Br ^- can be used in combination with. With respect to the adsorbent, reference can be made to, for example, the descriptions in U.S. Pat. Nos. 4,804,621 and 4,801,523 and European Patent 302,528 A2.

When the above selective growth is not perfect and a high iodine content surface layer is laminated on the low iodine content surface layer with 50 lattice layers or less, an AgX solvent is added to the emulsion for ripening. By doing so, the laminated portion may be removed. In this regard, the description in JP-A-63-31244 can be referred to. Usually, the depth of the depression becomes smaller as the addition amount of the AgX solvent is reduced, the aging time is shortened, and the aging temperature is lowered. Therefore, various AgX particles in which these factors were changed were produced, and the depth of the formed depression was determined by T
Appropriate etching conditions can be determined by measuring with an EM image.

(B) Chemical sensitization method As described above, as shown in FIG. 1, a surface layer having twin planes parallel to each other and different in iodine content from each other in the main plane. After forming AgX grains having an iodine content surface layer and a low iodine content surface layer, chemical sensitization is carried out, and a preferential treatment is performed on the surface of the low iodine content surface layer (hereinafter referred to as A-side). To form a chemical sensitizing nucleus. In this case, first, an adsorbent preferentially adsorbing is adsorbed on a crystal surface on which a chemical sensitization nucleus is not preferentially formed (hereinafter, referred to as a B surface). It is preferable to prevent the formation of a chemical sensitization nucleus on the substrate. In general, like cyanine dyes, mainly van
The adsorption strength of the adsorbent that is adsorbed by the der Waals force is
It is known that (AgCl <AgBr <AgBrI). Therefore, when the cyanine dye is adsorbed, the adsorption density is unevenly distributed (on the high iodine content surface layer> low iodine content surface layer). On the other hand, antifoggants and merocyanine dyes having an affinity for Ag ⁺ are generally expressed in the acid form (HL), and the solubility product pKsp = −log [Ag ⁺ ]
[L ^-] and when comparing the AgX of pKsp, AgX
Is larger than the pKsp value, and is preferentially adsorbed on the AgX particles having the larger difference, so that the adsorption density is (AgBrI <AgBr <AgCl). Therefore, when these compounds are adsorbed, the adsorption density becomes (on the high iodine content surface layer <low iodine content surface layer). In general, the larger the difference in iodine content between the high iodine content surface layer and the low iodine content surface layer, the larger the adsorption density difference.

As described above, there are the following two typical methods for producing the silver halide of the present invention. That is, after the adsorbent is adsorbed on the high iodine content surface layer, a chemical sensitizer is added to perform chemical sensitization, and a chemical sensitization nucleus is preferentially formed on the low iodine content surface layer. After adsorbing the adsorbent on the low iodine content surface layer, a chemical sensitizer is added and chemically sensitized, and the chemical sensitization nucleus is preferentially formed on the high iodine content surface layer. It is a method of forming. Of these, the mode for is more preferable. This is because usually, when a latent image is formed on the surface layer having a low iodine content, the initial development speed is higher and rapid development processing can be performed.

As described above, as a more preferred embodiment of the present invention, the region where the chemical sensitizing nuclei are formed is limited, and the number of chemical sensitizing nuclei per unit area (number / cm) at the region is defined.
² ) can also be a limited embodiment. The following two methods can be cited as methods for realizing this mode.

(1) First, an adsorbent which preferentially adsorbs on the surface B of the AgX emulsion grains is adsorbed, and then, an adsorbent for limiting the number of chemical sensitizing nuclei per unit area on the surface A is defined. Is added. In this case, examples of the adsorbent include an adsorbent that is adsorbed on the A surface and the B surface and has a small adsorption selectivity, and an adsorbent that selectively adsorbs on the A surface. (2) Usually, even though the adsorbent preferentially adsorbs on the B surface, the selectivity is not perfect. Therefore, a part is also absorbed on the A surface. In general, as the adsorption coverage increases, the selective adsorptivity decreases. Therefore, even when only the adsorbent that preferentially adsorbs on the surface B is used, the above “more preferred embodiment” is achieved.

As an adsorbent whose adsorption strength increases with an increase in iodine content on the surface of the object, a cyanine dye can be cited, and specific examples thereof include (1,1'-diethyl1-).
2,2'-cyanine chloride),
(1,1,3,3'-tetramethy1-2,
2'-cyanine), (anionic 9-meth)
y1thiacarbocyanine), [5,5 '
-Phenyl-9-ethyl-3,3 '-(2-sulfoethyl) -oxacarbocyanine-pyridinium salt], [D
ye 1 = 5,5′-chloro-9-ethyl-3,3′-
(3-sulfopropyl) -oxacarbocyanine Na
Salt], and the following Dye 2 and Dye 3. Among them, Dye 1 is particularly preferable because its iodine content dependence of adsorption is particularly large. For specific examples of other cyanine dyes, reference can be made to Japanese Patent Application No. 63-251215 and the descriptions of the following documents.

[0047]

Embedded image

[0048]

Embedded image

On the other hand, examples of adsorbents whose adsorption strength increases as the iodine content of the substrate decreases include the antifoggants and merocyanine dyes as described above. In this case, the adsorbent has a pKsp value of 9.5 to 1 at 25 ° C.
Compound 6 is preferred, and specific examples are as follows. As an antifoggant, 1-phenyl-5-m
ercaptotetrazole (pKsp: 16.
2), 5-methylbennzo-triazo
le (13.6), benzotriazole (13.5), 5,6-Jimethylbennzo-
triazole (12.7), 5-brombe
nzo-triazole (pKsp: 12.7), 4
-Nitro-6-chiorobenzotriaz
ole (same as 11.2), 2-mercapto-4-m
ethl-6,6'-dimethylpryrimi
Dine (from 14 to 14), 5-nitrobenzotr
iazole (11.8), benzimidazo
le (11.5), 2-methylbenzimid
azole (12.2), 4-hydroxy-6
methyl-1,3,3a, 7-tetraazai
ndene (10-11).
For other specific examples, reference can be made to the descriptions in the literature described below. Examples of the merocyanine dye include dyes represented by the following formulas (1) to (4).

[0050]

Embedded image

R ¹ , R ² and R ³ are H, preferably any of a substituted or unsubstituted alkyl group or aryl group having 18 or less carbon atoms, and the substituent is a carboxy group, a sulfo group or a cyano group. Groups, a halogen atom, a hydroxyl group, an alkoxycarbonyl group, an alkoxy group, a monocyclic aryloxy group, an acyloxy group, an acyl group, a carbamoyl group, a sulfamoyl group, and an aryl group. X is O, N, S, or Se; Y is O,
S or Se, and n is 0, 1, 2, 3, or 4
It is.

For other specific examples, reference can be made to the descriptions in the literature described below. These dyes (adsorbents)
In practice, the adsorption characteristics due to the difference in the halogen composition on the target surface can be practically examined by the following method, and a preferable compound can be selected and used. That is, although the above-mentioned general tendency is exhibited, for example, among cyanine dyes, there are a dye having a large dependence on the halogen composition of the cyanine dye and a small dye. In the present invention, it is particularly preferable to select and use the adsorbent having a large halogen composition dependency by the following method.

1) It can be examined by measuring adsorption isotherms of various adsorbents to AgX emulsions having the same shape and the same particle diameter and different halogen compositions (the total surface area of all grains is equal). For this, see T.W. H. Jam
s, The Theory of The Photo
graphic Process, FourthEdi
, Macmillan, New York
k, Chap. 9 (1977) can be referred to.

2) As a simple method, the following method is effective. Two or more AgX emulsions (A,
B,. . . ) Is dissolved and mixed. While stirring under conditions to be compared (pH, temperature, pAg, etc.), two or more types of emulsion-coated films (films independently coated with AgX emulsions of A, B, ...) are immersed. A sensitizing dye is added thereto, and the coated film is taken out after being suitable for adsorption equilibrium.
The adhered emulsion is removed by washing with water, and the spectral adsorption spectrum of the sample is measured comparatively using an integrating sphere spectrometer.
In this case, there is an advantage that particles to be compared can be easily separated and taken out and examined without using centrifugation or the like. 3) Other methods described in JP-A-64-40938.

The adsorption power of these sensitizing dyes and antifoggants to AgX grains depends on the crystal habit and the halogen composition of the target crystal surface, as well as the various atmospheres of the emulsion (emulsion pH, pA
g, coexistence of an adsorption promoter, etc.). Therefore, it is possible to adjust the adsorption strength of the sensitizing dye or the antifoggant by utilizing the knowledge. For example, it is preferable that the antifoggant is adsorbed under a condition of a pH not lower than its pKa by 1 or more. Here, Ka is the acid dissociation constant of the antifoggant. In general, the sensitizing dye is more likely to form a J-aggregate as the adsorptivity becomes stronger. J-aggregates are preferred because they more fully prevent the formation of chemical sensitizing nuclei. For details of these, and for other specific examples of the above-mentioned cyanine dyes, antifoggants and merocyanine dye compounds, see T.W. H. James, The Th
eoryof The Photographic P
process, Fourth Edition, Mac
Millan, New York, Chap. 1,
9, 13 (1977); Glafkides,
Chimie et Physique Photogr
aphiques, Fifth Edition,
Edition de l'Usine Nouvelle
le, Paris, Part 6 (1987), Japanese Patent Application No. 1
No. 15754 (see JP-A-2-196236), JP-A-61-14630, and E.C. J. Bir
r, Stabilization of Photo
graphic SilverHalide Emul
sessions, Focal Press, London
n (1974); Weissberger, T
he Chemistry of Heterocyc
lic Compounds, Vol. 18, Int
erscience, New York (1964)
Year), Vol. 30, John Willey, New
York (1977), Research Disc
magazine, volume 176, item17643, (D
Ecmber 1978), 184, item
18431, (August 1979), 216
Vol., Item 21728, (May 1982), and the like.

The conditions for adsorbing the adsorbent are usually pAg
6-11, preferably 7-9.5, temperature 30-80 ° C,
Preferably it is 35-75 degreeC. In general, higher temperatures are preferred because they reach the adsorption equilibrium earlier and tend to form J-aggregates. Further, the amount of the adsorbent added to the AgX emulsion is preferably 20 to 130%, more preferably 40 to 95% of the saturated adsorption amount. The conditions for chemical sensitization of the silver halide grains of the present invention are usually such that the pAg is 6 to 11, preferably 7 to 9.5, the temperature is 30 to 80 ° C, and preferably 35.
７５75 ° C. In general, the lower the temperature, the better the selectivity of the formation of chemical sensitized nuclei. Here, the low temperature refers to 30 to 50 ° C.

As a chemical sensitization method to be used, a gold sensitization method using a gold compound (for example, US Pat. Nos. 2,448,060 and 3,320,069) and a sulfur sensitization method using a sulfur compound (for example, US Pat. 222, 264), a selenium sensitization method using a selenium compound, iridium, platinum, rhodium,
Sensitization with metals such as palladium (see, for example, US Pat.
448,060, 2,566,245, 2,5
No. 66,263), reduction sensitization with tin salts, thiourea dioxide, polyamine and the like (for example, US Pat. No. 2,487,8).
No. 50, 2,518,698, 2,521,92
No. 5) or a combination of two or more of these. In particular, sulfur sensitization and / or selenium sensitization and gold sensitization are preferably used in combination, and particularly preferably in the presence of thiocyanate.

Examples of the sulfur sensitizer include various sulfur compounds such as thiosulfates, thioureas, thiazoles, rhodanines, oxazolidines, polysulfides, and inorganic sulfur in addition to the sulfur compounds contained in gelatin. Specific examples are described in JP-A-63-301039, JP-A-63-229449, JP-A-64-74540, and JP-A-64-74040.
References can be made to the publications of -40938 and the documents described below. Specific examples of compounds include sodium thiosulfate and triethythioure.
a, 5-benzylidene-3-ethyirh
odanine, 3-allyl-4-oxo-oxa
zolidine-2-thion and the like. AgX
The content in the particle phase is 10 ⁻⁹ to 10 ⁻³ mol / mol AgX,
Preferably it is 10 ^-8 to 10 ^-4 mol / mol AgX.

As the gold sensitizer, a gold complex salt (for example, US Pat. No. 2,399,083) can be preferably used. More specifically, there may be mentioned chloroauric acid, alkali metal chloroaurate, potassium-lithiocyanate, auric trichloride, sodium aurithiosulfate, and auric-5-sulfobenzothiazole-2-sulfide chloride. AgX of gold sensitizer
The content in the particle phase is 10 ⁻⁹ to 10 ⁻³ mol / mol AgX,
More preferably, it is 10 ^-8 to 10 ^-4 mol / mol AgX.

These chemical sensitizations can be carried out in the presence of a chemical sensitization aid. Examples of the chemical sensitization aid used include compounds that control fog in the process of chemical sensitization and increase sensitivity, such as azaindene, azapyridazine, azapyrimidine, and thiosulfonate. A specific example is U.S. Pat. No. 2,131,038.
Nos. 3,411,914 and 3,554,757
No., JP-A-58-126526; F. Duffi
n, Photographic Emulsion
Chemistry, p. 138-143, Focal
Press (1966); Gahler, Ze
itschrift fur Wiss, Photo. ,
63 , 133 (1969).

As described above, the AgX emulsion of the present invention is chemically sensitized in the presence of an adsorbent which is selectively adsorbed on one crystal surface layer, and is preferentially chemically sensitized on the other crystal surface layer. It is manufactured by forming. The emulsion can be used as the AgX emulsion of the present invention by itself, but further thereafter
Additives such as a sensitizing dye, an antifoggant and a surfactant described below can be added and used.

Another preferred embodiment of the present invention is an embodiment in which the adsorbent is used in a function-separated type. That is, after the chemical sensitization, a part or the whole amount of the adsorbent is desorbed and removed, and a spectral sensitizing dye and a fogging inhibitor most preferable in photographic properties are newly added. In this case, there is an advantage that the type and the amount of the adsorbent can be selected under the most preferable conditions for controlling the generation site and the number / cm ² of the chemical sensitizing nucleus, without depending on the photographic properties. . Regarding this, JP-A-1-201
No. 651 can be referred to. In this case, other methods for desorbing the adsorbent after chemical sensitization include:
An adsorbent such as activated carbon and pure water are passed through a porous membrane ((the pore size <the AgX
(Particle size, activated carbon particle size). For the specific examples of the porous membrane, reference can be made to the description of Japanese Patent Application No. 1-76678 (see Japanese Patent Application Laid-Open No. 3-21339). )) May be preferably used in the AgX emulsion for desorption removal. In this case, it is preferable to use a porous membrane having a large specific surface area, such as a hollow porous membrane, because the equilibrium is quickly reached.

In addition, a gelatin solution containing activated carbon or ion-exchange resin particles is coated and hardened on an organic polymer base, or a gelatin solution is further coated thereon as an overcoat layer and hardened. In an AgX emulsion. After desorbing the adsorbent, a spectrally sensitizing dye and a fogging inhibitor, which are most preferable in terms of photographic properties, can be newly added. Sensitizing dyes that can be added include cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, holopolar cyanine dyes, hemicyanine dyes, styryl dyes, hemioxonol dyes, oxonol merostyryl and streptocyanin. Polymethine dyes can be mentioned. Specific examples of the compounds can be referred to the descriptions in the literature described below.

The antifoggants which can be added include, for example, tetraindenes, azoles such as benzothiazolium salts, nitroindazoles, nitrobenzimidazoles, chlorobenzimidazoles, bromobenzimidazoles , Mercaptothiazoles, mercaptobenzimidazoles, aminotriazoles, benzotriazoles, nitrobenzotriazoles, mercaptotetrazole (especially 1-phenyl-5-mercaptotetrazole), etc., and mercaptopyrimidines, mercaptotriazines such as oxazolythion Thioketo compounds such as benzenethiosulfinic acid, benzenesulfinic acid, benzenesulfonamide, hydroquinone derivatives, aminophenol derivatives, Shokuko acid derivatives, and ascorbic acid derivatives. Specific examples of the compounds can be referred to the descriptions in the literature described below. Others
Pendant dyes (compounds in which the sensitizing dye and the residue of the antifoggant are organically bonded) described in JP-A-3-109539 can also be preferably used.

In a preferred embodiment of the present invention, a cyanine dye is selectively adsorbed on the high iodine content surface layer, and a chemical sensitizing nucleus is preferentially formed on the low iodine content surface layer. The mode of the surface function separation type is as follows. (1) After the cyanine dye adsorbing preferentially on the high iodine content surface layer is adsorbed on the AgX particles, it is chemically sensitized and preferentially chemically enhanced on the low iodine content surface layer. Form nucleus.
If necessary, a cyanine dye, an antifoggant, a surfactant and the like are added to this emulsion to obtain an emulsion of the present invention. (2) After the chemical sensitization described in the above (1), a part of the cyanine dye is desorbed with an adsorbent such as activated carbon to obtain the most preferable adsorption coverage in photographic properties, and then an antifoggant, a surfactant or the like is obtained. To obtain an emulsion of the present invention. (3) After the chemical sensitization described in (1) above, 50 to 100% of the cyanine dye is desorbed. Next, among the cyanine dyes preferentially adsorbed on the high iodine content surface layer, a spectral sensitizing dye most suitable in terms of photographic properties is added in an optimum amount, and an antifoggant and a surfactant are added. To obtain the emulsion of the present invention.

The AgX emulsion of the present invention can be produced by utilizing the above-mentioned method.
The following conditions can be mentioned as conditions for producing the gX emulsion. The pH of the reaction solution during grain formation can be 2 to 10, but is preferably 8.0 to 9.5 when a reduction sensitized silver nucleus is introduced. With respect to this,
No. 146033 can be referred to.

The temperature during crystal growth is usually 40 to
80 ° C. can be used. As a method of adding silver ions and halogen ions added during the crystal growth period, a method of adding an aqueous solution of a silver salt and an aqueous solution of a halide salt is used.
Ultra-fine particle emulsion (AgCl, AgB
r, AgI and / or a crystal thereof), or a method of superimposing them.
Further, a method of increasing the addition rate of silver ions and halogen ions during crystal growth can be used. These are described in JP-A-2-14633 and JP-A-63-151.
Nos. 618, 59-45438 and U.S. Pat. No. 4,242,445 can be referred to.

In order to control the degree of supersaturation during the nucleation of the AgX particles of the present invention, to promote the ripening in the ripening process, to promote the growth in the crystal growth process, and to use the chemical sensitization. At times, a silver halide solvent can be used to effectively enhance chemical sensitization. Silver halide solvents often used include thiocyanates, ammonia, thioethers, thioureas and the like. These can be referred to the descriptions in the literature described below.

A core / shell type direct reversal emulsion may be formed by using the grains of the present invention as a core and used. This is described in Example 13 of JP-A-63-151618.
And U.S. Patent Nos. 3,761,276 and 4,269,927.
No. 3,367778 can be referred to. The above-mentioned grains may be used as a core to form a shallow latent emulsion. This is described in JP-A-59-1335.
No. 42, U.S. Pat. Nos. 3,206,313 and 3,317.
No. 322 can be referred to.

There are no particular restrictions on the additives that can be added from the time of grain formation to the time of coating of the AgX emulsion of the present invention.
Additives that can be added include an AgX solvent (also referred to as an aging accelerator), a dopant for AgX particles (a Group 8 noble metal compound, other metal compounds (such as gold, iron, lead, and cadmium)), a chalcogen compound, and an SCN. Compounds, etc.), dispersion media, antifoggants, stabilizers, sensitizing dyes (for blue, green, red, infrared, bankro, ortho, etc.), supersensitizers, chemical sensitizers (sulfur, selenium, tellurium) , Gold and Group 8 noble metal compounds, phosphorus compounds alone or in combination, most preferably a chemical sensitizer comprising a combination of gold, sulfur and selenium compounds, stannous chloride, thiourea dioxide , Reduction sensitizers such as polyamine and amine borane compounds), fogging agents (organic fogging agents such as hydrazine compounds, inorganic fogging agents), surfactants (antifoaming agents and the like),
Emulsion sedimentation agent, soluble silver salt (AgSCN, silver phosphate, silver acetate, etc.), latent image stabilizer, pressure desensitization inhibitor, thickener, hardener, developer (hydroquinone compound, etc.), development modifier For specific examples of compounds and methods of use, the description in the following literature can be referred to. Also,
Surfactants such as coating aids, hardeners, binders, and other additives usually added after chemical sensitization until the end of the coating process.
Photosensitive material property modifiers (plasticizers, antistatic agents, ultraviolet absorbers, light scattering or absorbing materials, matting agents, lubricants, fluorescent bleaches, dimensional stabilizers, adhesion inhibitors, etc.), photographic property modifiers (polyethylene oxide) And the like, a high contrast agent such as a glutaraldehyde compound, etc.), a halogen acceptor, a dye and the like, which can be added according to the purpose. About these specific compounds and the method of using them, and others, a support, a microcellular support, an undercoat layer, an antihalation layer, a surface protective layer, an intermediate layer, and an emulsion layer having a high sensitivity to a low sensitivity in order from the incident light side. A layer configuration in which two or more layers are disposed, an overcoat layer on the back surface for improving the back surface characteristics of the support, a simultaneous multilayer coating method, a drying method, use of hydrogen sensitization, a reaction device for producing an AgX emulsion, a stirring device, Exposure atmosphere (temperature, pressure, humidity, type of gas, etc.), exposure method (pre-exposure, high-intensity exposure, low-intensity exposure, etc.), type of light source (natural light, laser light, etc.), photographic processing agent and processing method For the self-suppressing type developer, partial particle development, anhydrous washing method, etc., the description in the following literature can be referred to.

The AgX emulsion of the present invention can be used as a color photographic material in addition to a black and white photographic material. In that case, a color development forming method, a layer structure, use of a color filter, a color image forming material that can be used, a color image forming agent that releases a photographically useful fragment such as a development inhibitor or a development amplifier during color development. Alternatively, a non-color image forming agent (for example, DIR coupler, super DIR coupler, DAR
Couplers, DTR compounds, etc.)
IR compounds, polymer colors, weakly diffusible dye-forming couplers, coloring dye-forming couplers and / or competing couplers for color image color masks, scavengers, bleaching of developed silver and omission of bleaching, image dye stabilizers, yellow filters Details such as omission of layers, specific examples of compounds, and methods of use can be referred to the descriptions in the following documents.

In addition, the AgX emulsion of the present invention can use any combination of known techniques and known compounds described in the following documents. Research Di
sclosure vol. 176 (item 1764
3) (December, 1978), vol. 184
(Item 18431) (August, 1979),
vol. 216 (item 21728) (May, 19
82), JCIA Monthly Report, December 1984, 18-27
Page, Journal of the Photographic Society of Japan, 49, 7 (1986), 5
2, 144-166 (1989), JP-A-58-1
13926 to 113928, 59 to 90842, 5
9-142539, 62-253159, 62-9
9751, 63-151618, 62-6251,
62-115035, 63-305343, 62
-269958, 61-112142, 56-50
1776, JP-A-2-14633, JP-A-2-838, Japanese Patent Application Nos. 63-78465, 62-208241, 62
266538, 63-220238, JP-A 1-2
97649, JP-A-1-131541, US Pat. Nos. 4,705,744 and 4,707,436,
T. H. James, The Theory of
The Photographic Process,
Fourth Edition, Macmilla
n, New York, 1977; L. Zel
ikmann et al. Written by Making and
Coating Photographic Emu
lsion (published by The Focal Press, 19
64), p. Glafkids, Chimie e
t Physique Photographique
s, Fifth Edition, Edition
del'Usine Nouvellee, Par
is, 1987, Second Edition,
Paul Montel, Paris, 1957.

The silver halide emulsion of the present invention can be provided with one or more (for example, two or three) layers on a support together with other emulsions, protective layers, intermediate layers and filter layers, if necessary. Further, the support may be provided not only on one side but also on both sides. Further, they can be overlaid as emulsions having different color sensitivity. The tabular grains can be used in a high hardening system. This is described in JP-A-58-11392,
Research Disclosure, Volume 184,
See August 1979, item 18431, section K.

The silver halide emulsion of the present invention can be used for black-and-white silver halide photographic materials (for example, X-ray photographic materials, printing sensitizers, photographic paper, negative films, direct positive photographic materials), color photographic light-sensitive materials (for example, Negative film, photographic paper, reversal film, direct positive color light-sensitive material, silver dye bleaching method, etc.). Further, a photosensitive material for diffusion transfer (for example,
Color diffusion transfer element, silver salt diffusion transfer element), photothermographic material (black and white, color), high density digital
1) It can also be used as a light-sensitive material, a light-sensitive material for holography, and the like.

The silver halide emulsion of the present invention is disclosed in
-269958, Example 1, 63-30534
No. 3, JP-A-63-151618, Example 13,
14, 60-95533, 59-142538
Gazette, JP-A-62-253159, and JP-A-1-1315
No. 41, Example 9, JP-A Nos. 62-266538 and 63-220238, and Japanese Patent Application No. 62-208.
241 and 63-78465.

[0076]

The silver halide (AgX) agent of the present invention has the following features. (1) Since the generation sites of chemical sensitization nuclei and the number of generation sites and the number per unit area are sufficiently limited, dispersion of a latent image is prevented, and an AgX emulsion having high density and good development progress can be obtained. (2) When the cyanine dye is selectively attached to the surface of the high iodine content surface layer, the latent image forming portion and the color sensitizing portion are separated well, and the light absorption process, the latent image forming process, and the developing process On the other hand, the effect of the surface function separation type as described in Japanese Patent Application No. 63-251215 (see JP-A-2-34) can be obtained.

[0077]

【Example】

Reference Example 1 1 L of an aqueous solution containing KBr 4.59 and 7 g of gelatin having an average molecular weight (M) of 20,000 (pH 6.5, 30
℃), AgNO ₃ by the double jet method with stirring
Aqueous solution (with 32 g of AgNO ₃ and M = 0.7 g of 20,000 gelatin, 0.14 mL of HNO ₃ (1N) in 100 mL) and aqueous KBr solution (25.29 KBr and 0.7 g of M = 100 mL in 100 mL) (Including 20,000 gelatin) at the same time at 25 mL / min.
L was added. One minute later, 545 mL of an aqueous gelatin solution (32 g of deionized alkali-treated gelatin, pH 6.5) was added, mixed uniformly, and then heated to 75 ° C. After the temperature was raised, it was aged for 12 minutes, and then an aqueous solution of AgNO ₃ (1
(5% by weight) was added over 3 minutes. Next, a mixed solution of 10 mL of an aqueous solution of NH ₃ (25% by weight) and 10 mL of an aqueous solution of NH ₄ NO ₃ (50% by weight) was added, and the mixture was aged for 30 minutes. Next, a 3N HNO ₃ solution was added, and the pH was adjusted.
Adjusted to 6.5. Next, 16 mL of an aqueous solution of KBr (10% by weight) was added, and a silver potential of -20 mV (vs. saturated calomel electrode) was used using an aqueous solution of AgNO ₃ (15% by weight) and an aqueous solution of KBr. D. J. Was added. AgNO ₃ aqueous solution was first added at 8 mL / min for 10 minutes, followed by addition at 15 mL / min for 20 minutes. Characteristics obtained from the TEM images of the emulsion grains sampled at this time were as follows. Average particle size 1.0 μm, average thickness 0.17 μm, C.I. V. 10.5%,
The area ratio of the average particles was 99.9%. The emulsion was subsequently added at 75 ° C. with a KBr solution and pBr 0.9
AgBr _0.9 I _0.1 fine grain emulsion described below was added to 0.48
After aging for 12 minutes, the temperature was lowered to 30 ° C., and the emulsion was washed with sedimentation washing water and redispersed at 40 ° C.
pH 6.4, pBr 2.85. Then raise the temperature to 55 ° C
I made it. TEM of emulsion grains sampled at this time
The image was observed. The measurement results of the TEM image were as follows. Average thickness of the tabular grains: 0.17 μm Average diameter of the tabular grains: 1.46 μm V. : 11.9% Area ratio occupied by the tabular grains: 99.9% Area ratio occupied by hexagonal tabular grains in the tabular grains: 9
9.7%

That is, AgBr _0.9 I _0.1
Indicates that the AgBr tabular core particles were laminated only in the lateral direction. The number of twin planes of the hexagonal tabular grains was two from the low-temperature TEM image of the grains. 5,
5'-dichloro-9-ethyl-3,3'-bis (3-
Sulfopropyl) -oxacarbocyanine Na salt was added at 90% of the saturated adsorption amount, and 10 minutes later, 5-benzylidene-
A methanol solution of 3-ethylrhodanine was added in an amount of 8 × 10 ⁻⁶ mol / mol AgX, and then an aqueous KSCN solution was added to 3 × 10 ⁻⁶ mol / mol AgX.
Only × 10 ⁻⁴ M / mol AgX was added. After 3 minutes, an aqueous solution of chloroauric acid was added at a concentration of 5 × 10 ⁻⁶ mol / mol AgX,
Aged for 20 minutes. The temperature was lowered to 40 ° C., and the antifoggant (TAI (4-hydroxy-6-methyl-1,3,3
a, 7-Tetraazaindene) was added only at 7 × 10 ⁻³ mol / mol AgX, and after 10 minutes, a coating aid (sodium dodecylbenzenesulfonate) and a thickener (poly (4-sulfostyrene) sodium salt) And, together with a gelatin protective layer, silver 1.59 / silver on a cellulose triacetate transparent base.
m ² and dried.

Comparative Example 1 The same AgBr tabular core emulsion as in Reference Example 1 was prepared. Next, AgBr was grown on the core particles. That is, a KBr solution was added at 75 ° C. to make pBr 0.9, 0.4 g mol of an AgBr fine grain emulsion described later was added, and after ripening for 7 minutes, the temperature was increased to 30 ° C.
, Washed with water by sedimentation, redispersed at 40 ° C, and then brought to a temperature of 55 ° C. Observation of a TEM image of the emulsion grains sampled at this time revealed the following. This indicates that the shell AgBr grew only in the lateral direction of the core particle. Average thickness of the tabular grains: 0.17 μm Average diameter of the tabular grains: 1.46 μm V. 11.0% Area ratio occupied by the tabular grains: 99.9% The emulsion was then subjected to the same steps as in Reference Example 1 and coated.
Let dry. Exposure of the emulsion coatings of Reference Example 1 and Comparative Example 1 with blue light for 1 second (the exposure amount is 5 times the exposure amount that gives the maximum density)
did. Next, the toner is suppressed and developed according to the method described in JP-A-64-62631, and the T of the carbon replica of the particles is determined.
The EM image was observed. The ratio of the starting point of the development of the particles on the surface of the core particles was as shown in Table 1. Further, the emulsion coatings of Reference Example 1 and Comparative Example 1 were exposed to blue light through an optical wedge for 10 ⁻² seconds, and were exposed to MAA-1 developer at 20 ° C.
Developed for 10 minutes. Table 1 shows the relative quantum sensitivities obtained from the obtained characteristic curves and the light absorptivity of the AgX particles. The effect of the silver halide grains of Comparative Example 1 in which the latent image was preferentially formed on the low iodine content surface layer was confirmed.

[0080]

[Table 1] 上 On core surface: Others Relative quantum sensitivity ─── Reference Example 1 6: 1 125 Comparative Example 1 1: 2 100 ───────────────────────────────

REFERENCE EXAMPLE 2 In the reference example 1, NH ₄ NO
Make the same up to the point where ₃ and NH ₃ are added. Then one
Aged for 8 minutes. Then add 3N HNO ₃ solution,
The pH was adjusted to 6.5, and an aqueous solution of KBr (10% by weight) 16
mL was added. AgNO ₃ aqueous solution (15% by weight) and K
Using an aqueous Br solution, C.I. D. J. Addition (silver potential -20m
V). The addition was performed at 8 mL / min for 3 minutes. The characteristics obtained from the TEM images of the emulsion grains sampled at this time were as follows. Average particle size 0.6 μm, average thickness 0.16 μ, C.I. V. 13%, and the area ratio of tabular grains was 99.9%. Subsequently, a KBr solution was added to the emulsion at 75 ° C. to obtain pBr _0.9, and 0.1 mol of AgBr _0.9 I _0.1 fine particles described later was added thereto to obtain pBr _0.9.
Aged for minutes. Next, 0.24 mol of the fine particles were added, and after aging for further 12 minutes, the temperature was lowered to 30 ° C., and the emulsion was washed with water by sedimentation washing, redispersed at 40 ° C., and pH 6.4, p
Br was adjusted to 2.85. At this time, the TEM of the emulsion grains sampled was observed. The observation results were as follows.

Average thickness of the hexagonal tabular grains: 0.16 μm Average particle size of the hexagonal tabular grains: 1.28 μm in diameter C.I. V. : 12.5
% The area ratio occupied by the hexagonal tabular grains: 99.8% The emulsion is then subjected to the same steps as in Example 1 and coated.
Let dry. The sample was exposed to blue light for 1 second (the exposure amount was 5 times the exposure amount that gave the maximum density). Next, suppression development was performed by the method described above, and a TEM image of a carbon replica of the particles was observed. The percentage of development start points of the particles on the surface of the core particles was 85%. Since the average particle diameter of the AgBr core was smaller than that in Example 1, the latent image was more concentrated at the center of the main plane of the average particles.

Example 1 AgBr _0.9 I in Reference Example 1
Only the lamination conditions of _0.1 were as follows. That is, the silver potential is set to +35 mv, and an AgNO ₃ aqueous solution (15% by weight) is used.
Was initially 6.4 mL / min, linear flow acceleration 0.12 mL / min.
The CDJ was added (silver potential +35 mV) for 43 minutes.
The silver halide salt aqueous solution has KBr and KI of 0.9: 0.1.
An aqueous solution containing a molar ratio was added. After the addition, the mixture was stirred for 3 minutes. Observation of a TEM image of the obtained emulsion particles revealed the following characteristics. Average thickness of the tabular grains: 0.2
2 μm, average particle size: 1.07 μm. Therefore, in this case, it is shown that the AgBr core tabular grains grew both in the vertical direction and in the horizontal direction. Next, add K
An aqueous Br solution was added to make pBr 0.9, and AgBr described later was used.
0.106 mol of a fine grain emulsion was added, and the mixture was ripened at 75 ° C for 5 minutes. Next, the temperature was raised to 30 ° C, and the water was washed with the sedimentation washing method.
And redispersed.

Observation of a TEM image of the obtained emulsion particles revealed the following characteristics. Accordingly, it was confirmed that the emulsion grain structure had the structure shown in FIG. 1 (b). Average thickness of the tabular grains: 0.22 μm Average particle size of the tabular grains: 1.12 μm φ C.I. V. : 12% Area ratio occupied by the tabular grains: 99.9% The emulsion was then subjected to the same steps as in Reference Example 1, and coated.
Let dry. The sample was suppressed and developed by the same method as in Reference Example 1, and the development start point was observed with a TEM image. Development start point is
The ratio of the compound present on AgBr finally grown was 83%, confirming the effect of the present invention.

The sample was passed through an optical wedge and -blue
Exposure was performed for 10 ^-2 seconds with light (light obtained by removing blue light from white light), and developed with Fuji Photo Film Co., Ltd. developer "Hirendol" at 20 ° C for 4 minutes. Excellent photographic properties were exhibited. The samples of Reference Examples 1 and 2 and Example 1 were exposed to -blue light for 1 second (the exposure amount was 5 times the exposure amount that gave the maximum density), and suppressed development was performed in the same manner as in Reference Example 1. Was observed in a TEM image. The ratio of the development start point on the AgBr surface was 85% in Reference Example 1, 83% in Reference Example 2, and 83% in Example 3.
The effect of the present invention was also confirmed in the case of -blue light exposure.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a specific example of the structure of AgX particles of the present invention. (A) to (c) show examples of the cross-sectional structure of the tabular grains, and (d) and (e) show examples of the top view of the tabular grains of (a).

FIG. 2 is a schematic diagram showing an estimated cross-sectional structure of a halogenated particle described in JP-A-58-113927.

[Explanation of symbols]

 (A) Low iodine content part (b) Chemical sensitization nucleus (c) Cyanine dye (d) High iodine content part (e) Main figure (A) Center line

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03C 1/035 G03C 1/015 G03C 1/09

Claims (6)

(57) [Claims] 1. A silver halide grain comprising at least 30% of the projected area of all silver halide grains.
A silver halide emulsion in which silver halide grains in an amount corresponding to the above have twin planes parallel to each other and whose main planes are substantially flat. Silver iodide grains, a high iodine content surface layer having a surface exposed in the main plane, and a high iodine content surface layer formed around the high iodine content surface layer along the main plane. A low iodine content surface layer having an iodine content lower than 3 mol% or more, and a chemical sensitization nucleus is preferentially formed on the low iodine content surface layer. Silver halide emulsion. 2. The ratio of the area of the surface of the high iodine content surface layer to the area of the low iodine content surface layer exposed on the main plane in the silver halide grain having a twin plane is ３. ~
The silver halide emulsion according to claim 1, wherein the ratio is in the range of 35/1 (area of high iodine content surface layer surface / low iodine content surface layer surface area). 3. In the silver halide grains having twin planes, the number of chemical sensitization nuclei preferentially formed on the low iodine content surface layer per unit area is high iodine content. 3. The silver halide emulsion according to claim 1, wherein the number of chemical sensitization nuclei formed on the surface layer is at least twice the number per unit area. 4. In the silver halide grains having twin planes, the number of chemically sensitized nuclei preferentially formed on the low iodine content surface layer per unit area is high iodine content. 3. The silver halide emulsion according to claim 1, wherein the number of chemical sensitization nuclei formed on the surface layer is at least 5 times the number per unit area. 5. 60% of the projected area of all silver halide grains
The silver halide emulsion according to any one of claims 1 to 4, wherein the silver halide grains in an amount corresponding to the above are silver halide grains having the twin plane. 6. The silver halide grains having a twin plane having an aspect ratio in the range of 3 to 20 and a coefficient of variation of 2
0% or less of monodisperse parallel double twin grains, wherein the iodine content of the high iodine content surface layer is 7 to 35 mol more than the iodine content of the low iodine content surface layer. The halogenation according to any one of claims 1 to 5, wherein the cyanine dye is preferentially adsorbed on the high iodine content surface layer, with the mole percentage being increased in the mole% range of the% range. Silver emulsion.