JP2840897B2 - Silver halide emulsion and method for producing the same - 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 {100} main plane and an aspect ratio of 1.
An object of the present invention is to provide an AgX emulsion having three or more tabular AgX grains and a method for producing the same.

[0002]

2. Description of the Related Art When a tabular AgX emulsion particle is used in a photographic light-sensitive material, color sensitization, sharpness, light scattering characteristics, covering power, development progress, graininess, etc. are improved as compared with a non-tabular AgX particle. You. For this reason, tabular grains having twin planes parallel to each other and having a principal plane of {111} plane have come to be used frequently. For details, refer to
8-113926, 58-113927, 58
-113928, JP-A-2-838 and 2-286
Nos. 38 and 2-298935 can be referred to. However, when a large amount of a sensitizing dye is adsorbed on AgX particles, particles having a {100} plane usually have better color sensitization characteristics. Therefore, development of tabular grains having a {100} major plane is desired. The {100} tabular grains whose main plane is a quadrangle are disclosed in JP-A-51-8801.
No. 7, JP-B 64-8323. But,
Any halogen composition of the central portion of these particles, I ^-
It has a low I ^- content of less than 1 mol%. The particles shown in the examples are particles having a uniform composition as a whole. There is no description about core / shell type tabular grains having a core layer and one or more shell layers. Further, all of these emulsion grains are grains formed only in the process of (nucleation → ripening), and have the disadvantage that the grain size and AgX yield, that is, sensitivity and image quality cannot be freely controlled and improved. In all of the examples of these patents, since the nuclei having a uniform halogen composition are formed, the generation probability of the tabular grains varies, and the reproduction accuracy is poor.

[0003]

SUMMARY OF THE INVENTION The object of the present invention is to provide sensitivity,
An object of the present invention is to provide an AgX emulsion having further improved image quality. Furthermore, the reproducibility of tabular grain formation is good, and the grain size and Ag
It is an object of the present invention to provide a method for producing AgX emulsion grains in which X yield, that is, sensitivity and image quality can be freely controlled.

[0004]

The object of the present invention has been attained by the following items. (1) A method for producing a silver halide emulsion in which 20% or more of the total projected area of the silver halide emulsion grains are tabular grains having a {100} major plane and an aspect ratio of 1.3 or more, The tabular grains are composed of tabular grains having a core portion having an iodine content of 1.2 mol% or more or a core layer and a shell layer, and the iodine content of at least one shell layer is the iodine content of the core layer. 20% or more of the tabular grains, the production method being produced through at least the steps of silver halide nucleation, ripening and crystal growth,
And the nucleation is at a Br ion concentration of ^10-2.3 mol /
A silver halide emulsion grain, wherein the ripening and the crystal growth are performed at an Ag ion concentration and a Br ion concentration of 10 to ^2.3 mol / l or less.

(2) The conditions for the solution during the crystal growth are as follows: silver halide fine particles having an Ag ion concentration and a Br ion concentration of not more than ^10-2.3 mol / liter and a particle size of not more than 0.15 μm. (1) The method for producing silver halide emulsion grains as described in (1) above, wherein the addition is performed.

First, the structure of the AgX grains of the present invention will be described in detail, and then the method for producing the emulsion grains will be described in detail. (A) AgX grain structure The AgX emulsion of the present invention has at least a dispersion medium and AgX grains, and 20% or more, preferably 40% or more, more preferably 60% or more, and most preferably the total projected area of the AgX grains. 80% or more are tabular grains having the following characteristics. That is, the main plane is {100} plane and the aspect ratio is 1.
3 or more, preferably 2 or more, more preferably 3 to 20,
More preferably, 4 to 16 tabular grains are used. Here, the aspect ratio refers to (diameter / thickness) of tabular grains, and the diameter refers to the diameter of a circle having an area equal to the projected area of the grains when the grains are observed with an electron microscope. Also,
Thickness refers to the distance between the major planes of the tabular grains. The projected particle size of the tabular grains is 10 μm or less, and preferably 0.1 μm or less.
It is 5-5 μm, more preferably 0.2-3 μm. The projected particle size distribution of the particles is preferably monodispersed, and the variation coefficient of the projected particle size distribution is preferably 40% or less.
% Or less, more preferably 20% or less. Here, the variation coefficient is expressed in% of a value obtained by dividing a variation (standard deviation) of a particle size represented by a circle-converted diameter of a projected area of the particle by an average particle size. The shape of the main plane is a right-angled parallelogram or a shape in which four corners of a right-angled parallelogram are rounded. More preferably, the ratio of the adjacent sides of the right-angled parallelogram is 2 or less, further preferably 1.5 or less. However, when the corner is rounded, the straight portion of the side is extended, and the length between the intersections is defined as the side length. Ag of the present invention
In the first embodiment of the X particles, the I ^- content at the center of the particles is more than 1.2 mol%, preferably 1.5 to 7 mol%,
More preferably, it is 2 to 5 mol%. That is, AgCl,
AgBr and its mixed crystals are particles having an I ^- content in accordance with the regulation. Preferably, the particles have a CI ^- content of 50 mol% or less. The second embodiment of the AgX particles of the present invention is as follows. The particles have a core layer and one or more shell layers, further, at least one layer of I shell layer ^- content of the core layer I ^- 20% of the content: more, preferably 40% or more, more preferably It is characterized by being 100% and 10 mol% or less. More preferably, the I ^- content of the whole particles is more than 1.2 mol%, more preferably 1.5 to 7 mol%, more preferably 2 to 5 mol%.

FIG. 1 shows an example of a sectional structure of the core / shell type tabular grains. In the figure, a indicates the core layer, and b indicates the layer having a higher I ^- content than the core layer. (1) FIG. 1 shows an embodiment in which a shell layer is laminated on the entire surface of the core layer, and (2) FIG. 1 shows c on the entire surface of the particles in FIG.
An embodiment in which layers are stacked is shown. The iodine content of the c layer is 90% or less, preferably 60% or less, more preferably 30% or less of the i content of the b layer. (3) FIG. 3 shows an embodiment in which b is laminated on the edge of the core particle, and (4) shows an embodiment in which c is laminated on the edge of the particle in FIG. FIG. 5 (5) shows an embodiment in which b is laminated on the main plane of the core particle, and FIG. 6 (6) shows an embodiment in which c is laminated on the main plane of the particle in FIG. 5 (5). In addition, a combination structure of two or more of the structures shown in FIGS. 1A, 1B, and 3C can be given. For example, FIG. 7 shows an embodiment in which c is laminated on the edge of the particle in FIG. 5 and FIG. 8 shows an embodiment in which c is laminated on the edge of the particle in FIG.

The halogen composition of the particles is AgCl, A
gBr and a mixed crystal thereof, characterized in that the I ^- content complies with the above-mentioned regulations. The I ^- content of the layer a is preferably 7 mol% or less, more preferably 5 mol% or less, and still more preferably 1.2 to 5 mol%. The halogen composition change between the a-layer, the b-layer, and the c-layer may be any of a steep type, a gradual change type, and a stepwise change type, and can be selected according to each purpose. Regarding this, JP-A-60-143331,
No. 59-45438 and the following documents can be referred to. The core / shell molar ratio of the particles is not limited, but is usually from 1/25 to 25, preferably from 1/10 to 10/25.
It is 10.

(B) Method for producing the AgX emulsion particles Each of the AgX emulsion particles is formed through a process of nucleation → ripening → crystal growth. First, the nucleation process will be described in order.

1) Nucleation process Ag ⁺ salt solution and halide salt (hereinafter referred to as X ^- salt) while stirring in a dispersion medium solution containing at least a dispersion medium and water.
The solution is added by a double jet method to nucleate. The Br ⁻ concentration in the dispersion medium solution during the nucleation is 10 ^−2.3 mol / L or less, but is more preferably 10 ^−2.6 mol / L or less. The Ag ⁺ concentration is preferably 10 ⁻⁴ mol / L or more, more preferably 10 ^−3.7 to 10 ^−1.5 mol / L, and even more preferably 10 ^−3.4 to 10 ^−1.5 mol / L. As the X ^- salt, an alkali metal salt or an ammonium salt is usually used. AgNO ₃ is usually used as the Ag ⁺ salt. As the dispersion medium, a conventionally known photographic dispersion medium can be used, but usually gelatin is preferred, and alkali-treated gelatin is more preferred. The Ca ⁺⁺ content of the gelatin is preferably 0.
The optimum content of gelatin can be selected from the range of from 10 to 10 ⁴ ppm. By performing the cation exchange treatment, the Ca ⁺⁺ content can be adjusted.

For the details thereof, the description in the following literature can be referred to. The concentration of the dispersion medium in the reaction vessel is preferably 0.1% by weight or more, more preferably 0.2 to 10% by weight, even more preferably 0.3 to 5% by weight. Further, gelatin can be contained in the Ag ⁺ salt solution and / or the X ^- salt solution. In this case, the gelatin concentration is preferably from 0.1 to 5% by weight, more preferably from 0.2 to 3% by weight. A concentration approximately equal to the gelatin concentration in the reaction vessel is particularly preferred. Here, “approximately” means that (concentration difference / gelatin concentration in reaction vessel) is preferably within 50%, and 25% or less.
Is more preferable. When the AgNO ₃ solution and the X ^- salt solution are added below the liquid level in the container solution, non-uniformity of the gelatin concentration near the addition port is eliminated, and uniform nucleation can be achieved.

The temperature at the time of nucleation is not limited.
0 ° C. or higher is preferable, and 20 ° C. or higher is more preferable. After nucleation, physical ripening is performed to eliminate non-tabular grains and grow the tabular grains. Therefore, in order to perform the ripening more quickly, it is preferable to lower the nucleation temperature.
However, when the nucleation temperature is increased, ripening occurs during nucleation. Ag ⁺ salt addition rate is 2 per liter of container solution.
-30 g / min is preferable, and 4-20 g / min is more preferable. The nucleation period is preferably 15 minutes or less, and 5 seconds to 10 minutes.
Minutes, more preferably 15 seconds to 5 minutes.
Although the pH in the container solution is not particularly limited, it is usually pH 11
Hereinafter, preferably, a preferable value of 1.5 to 10.5 is selected and used. The number formed during the nucleation (the number of defects / particles) = ω depends on the nucleation conditions. The tabular grains are formed because the edge faces grow preferentially with respect to the main plane. This is because defects having selective growth characteristics (eg, screw dislocations) are present on the edge surfaces of the grains. ω
Means the number of the defects contained per particle. For example, in the case of AgBr nucleation, the value of ω is 7 to
Maximum in 8 regions, lower or higher pH
Decrease as you move away. The excess ion concentration of Ag ⁺ becomes maximum around 10 ⁻² to 10 ⁻³ mol / l,
It decreases with increasing distance. The lower the gelatin concentration in the container solution, the higher the gelatin concentration, but if it is 0.1% by weight or less, various defects are introduced, and the ratio of non-tabular defect particles increases. Increasing the rate of addition of the AgNO ₃ and X ^- salt solutions, but increasing the rate too much will increase the proportion of non-tabular defect grains. It decreases as the stirring level increases. The greater the degree of deionization of the gelatin in the container solution, the less. The higher the temperature, the lower the temperature.

These are the results when the nuclei are formed with the other conditions being the same and only one condition being changed. That is, after forming nuclei under various conditions, the gelatin concentration, pAg, pH, etc. were changed under the same conditions (pH 6.5, Ag ⁺ concentration ≒ Br ^−).
(Concentration, gelatin concentration = 2% by weight), heated to 75 ° C, and aged. Emulsion was sampled for the ripening time, and the average volume of tabular grains was determined from a grain photograph (referred to as a transmission electron micrograph of a replica of the grains) at the time when non-tabular fine grains were almost completely eliminated. It is.
Alternatively, it can also be determined by sampling an emulsion at an early stage of ripening (for example, immediately after raising the temperature) and counting the tabular grain number ratio from a grain photograph. These factors are additive to each other. If the ω value is too low, the probability of forming the tabular grains will be low. Therefore, the nucleation conditions are adjusted and the ω value is adjusted so that the ω value is not too high or too low, and the projected area ratio of the tabular grains of the finally obtained emulsion falls within the above-mentioned range. . In the first embodiment of the present invention, the I ^- content of AgX formed during nucleation is 1.2 mol% or more, preferably 1.5 to 7 mol%, more preferably 2 to 5 mol%. In this case, the increase in the ω value caused by increasing the I ^- content may be adjusted to an appropriate value by adjusting other factors.

A of the reaction solution to be controlled during the nucleation
Since the g ⁺ and Br ⁻ excess ion concentrations are very low, precise control thereof is difficult. As a control method, a conventional silver potential control method can be used, but the following method is more effective. Without using the silver potential control method, the AgNO ₃ solution and the Br ⁻ salt solution are simultaneously mixed and added at a preset flow rate and time by a precision liquid sending pump. Further, in order to reduce non-uniformity of concentration at the time of stirring and mixing, it is more preferable to add through a porous material. Regarding this, Japanese Patent Laid-Open No.
Nos. 33, 21339 and 3-326
No. 222 can be referred to. It is more preferable to mix the Ag ⁺ salt solution and the X ^- salt solution after diluting them with the bulk liquid. For specific examples of this apparatus, see Japanese Patent Application Laid-Open No. 2-146033 and US Pat.
Nos. 85,777 and 3,415,650 can be referred to.

Further, the optimization of the ω value is performed by comparing Ag ⁺ and Br
^- it is preferably carried out at a distance from the equivalence point concentration range of. Specifically, an excess concentration of Ag ⁺ is preferably 10
^-3.4 mol / l or more, more preferably 10 mol / l or more
Nucleation occurs in the range of ^-3.0 to 10 ^-1.5 mol / liter. In this case, the influence of the variation in the addition accuracy of the AgNO ₃ solution and the Br ⁻ salt solution is reduced, which is preferable. When nucleation occurs in this region, the ω value usually becomes too high. However, the ω value may be reduced and optimized by controlling the above factors. Alternatively, there is a region where the ω value decreases as the Ag ⁺ excess concentration increases. The value of ω may be adjusted by adjusting the Ag ⁺ excess concentration in that region. In the case of manufacturing with a large amount of equipment, the concentration non-uniformity is usually large. In this case, a method of performing nucleation in a small container and accumulating in a large container is more preferable. Regarding this, Japanese Patent Application Laid-Open No. 3-155538
And Japanese Patent Application No. 3-139516 can be referred to. The degree of deionization of gelatin can be adjusted by adjusting the level of deionization of gelatin, but a method of changing the mixing weight ratio of (non-deionized gelatin: empty gelatin) is also preferably used. be able to. Here, deionization refers to gelatin in which impurity anions and cations in gelatin are deionized. Further, the mixing weight ratio can be changed between 1: 0 and 0: 1. e
The mpty gelatin refers to gelatin from which 90% or more of the impurity ions in the original gelatin have been removed.

2) Ripening process It is difficult to produce only tabular grain nuclei during nucleation. Therefore, grains other than tabular grains are eliminated by Ostwald ripening in the next ripening process. The ripening temperature is preferably higher than the nucleation temperature by 10 ° C. or more, more preferably 20 ° C. or more. Usually, 50 ° C or higher, preferably 60 to 90 ° C is used. When 90 ° C. or higher is used, aging is preferably performed under a pressure of at least atmospheric pressure, preferably at least 1.2 times the atmospheric pressure. For details of the pressure aging method, the description of Japanese Patent Application No. 3-343180 can be referred to.

The Ag ⁺ and Br ⁻ concentrations of the solution during ripening are preferably 10 ^-2.3 mol / l or less, and
^-2.6 mol / liter or less is more preferable. Solution p
H is preferably 2 or more, more preferably 5 to 11, and 6 to
10 is more preferred. When ripening under these pH and pAg conditions, mainly defect-free cubic fine particles disappear, and tabular grains grow preferentially in the edge direction. Ag ⁺ and B
As one moves away from the r ^- concentration condition, the preferential growth of edges decreases and the rate of disappearance of nontabular grains decreases. Further, the growth rate of the main plane of the particles increases, and the aspect ratio of the particles decreases. When the AgX solvent coexists during the ripening, the ripening is accelerated. However, the conditions are the halogen composition of the AgX particles,
It varies depending on pH, pAg, gelatin concentration, temperature, AgX solvent concentration, etc.
It is preferable to select the optimal condition by the AND error method. As described above, the halogen composition of the tabular core grains formed through the process of nucleation → ripening has an I-content of preferably 1.2 mol% or more, more preferably 1.5 to 7 mol%, and still more preferably. 2 to 5 mol%, Cl ^- content: is AgBrClI below 50 mol%. In the next crystal growth process, a shell layer is laminated on the core particles, or the shell layer is laminated after the core particles are further grown to a desired size.

[0018] 3) the crystal growth process Ag ⁺ and Br ^- excessive ion concentration of 10 ^-2.3 mol /
When the crystal is grown under low supersaturation conditions near the equivalent point of 1 liter or less, preferably 10 ^−2.6 mol / liter or less, the grains grow preferentially in the edge direction. In this case, Cl ^- excess concentration is preferably from 10 ^-1.2 mol / l, 10
^-1.5 mol / l or less is more preferred. As the distance from the vicinity of the equivalence point increases, and as the degree of supersaturation during the growth increases, the growth ratio in the main plane direction to the edge direction increases. When the Ag ⁺ concentration is increased from the equivalent point, the main plane shape is a right-angled parallelogram, and the growth rate in the thick direction increases,
As the Br ^- concentration is increased from the equivalence point, the corners of the right-angled parallelogram fall and the growth rate in the thick direction increases. When the pBr during crystal growth is set to an octahedral grain generation region (for example, pBr 1.2 to 2 in AgBr), all four corners of the tabular grains are dropped, and the edge plane changes to {111} plane.
It grows in the thickness direction and eventually becomes octahedral particles.

These conditions vary depending on the halogen composition of the particles, the pH of the solution, the temperature, the concentration of the AgX solvent, and the like. Therefore, after growing at various X ^- salt concentrations according to each case and confirming that desired particles are obtained,
It is preferred to prepare gX particles. For example, in the case of AgCl particles, Cl ^- excessive ion concentration of 10 ^-1.5 mol /
Even in liters, the tabular grains grow preferentially in the edge direction. The temperature at the time of crystal growth is usually 40 ° C. or higher, preferably 50 to 90 ° C. By utilizing these growth characteristics, the particles of the first embodiment and the particles of the second embodiment of the present invention can be formed. As a method of adding a solute during crystal growth, the following two methods are mainly effective.

(1) Fine grain emulsion addition method AgX fine grain emulsion having a diameter of 0.15 μm or less, preferably 0.1 μm or less, more preferably 0.06 to 0.006 μm is added, and the tabular grains are subjected to Ostwald ripening. Grow. The fine grain emulsion can be added continuously or intermittently. The fine grain emulsion can be continuously prepared by supplying the AgNO ₃ solution and the X ⁻ salt solution by a mixer provided near the reaction vessel, and can be immediately added to the reaction vessel immediately or in another vessel in advance. And then added continuously or intermittently. The fine grain emulsion can be added in a liquid form or as a dry powder.
The fine particles preferably do not substantially contain multiple twin particles. Here, the multiple twin particles refer to particles having two or more twin planes per particle. Substantially not included
A multiple twin particle number ratio of 5% or less, preferably 1% or less;
More preferably, it refers to 0.1% or less. Further, it is preferable that substantially no single twin particles are contained. Further, it is preferable that the composition does not substantially include a screw dislocation. Here, "substantially not included" complies with the above-mentioned rules. The halogen composition of the fine particles is AgCl, AgBr, AgBrI (I ^- content is preferably 20 mol% or less, more preferably 10 mol% or less) and a mixed crystal of two or more thereof.

The solution conditions during the grain growth are as follows:
Same as the condition. Both are for Ostwald ripening
Growing more tabular grains and eliminating other fine particles
This is because the process is mechanically the same. The fine particles
In particular, the emulsion addition method is to selectively treat the tabular grains in the edge direction.
It can be preferably used as a method for growing into a.
The reason is as follows. Select tabular grains in the edge direction
For selective growth, pBr during particle growth, temperature, p
H or other solution conditions (eg, AgBr particles
In the case, it is near the equivalence point), and the supersaturation degree is optimally selected.
There is a need. That is, the degree of supersaturation of the system
Lower than the supersaturation required for
Control to be higher than the minimum required supersaturation
There is a need. When fine particles are added and many fine particles coexist
In this case, the degree of supersaturation of the system is defined by the solubility of the fine particles.
In other words, by selecting the size of the fine particles,
This is because the degree of supersaturation can be precisely controlled to an optimum value. Fine particles
Is formed at a temperature of 40 ° C. or lower, preferably 30 to 10
Ag in dispersion medium solution at ℃⁺Salt solution and X^-Simultaneous mixing of salt solution
It is preferable to form by adding in a legal manner. The addition time is
It is preferably 12 minutes or less, more preferably 6 minutes or less.
Ag in the dispersion medium solution during the addition⁺And Br ^-The concentration of
(Ag⁺Concentration <Br^-Concentration) and Br^-Concentration <1
0^-1.7Mol / liter, preferably Br^-Concentration = 10^-2
-10^-3.5Mole / liter is more preferred. It is said
This is because the mixing ratio of twin particles can be reduced.
You. Furthermore, the mixing ratio of defect particles such as the screw dislocations described above
It is because it can reduce. Addition of the fine grain emulsion
For details of the general law, refer to Japanese Patent Application No. 2-142635,
It is possible to refer to the description in JP-A-1-183417.
Wear.

(2) Ion solution addition method The Ag ⁺ salt solution and the X ^- salt solution are added simultaneously at an addition rate that does not substantially generate new nuclei to grow the tabular grains. Here, “substantially” means that the projected area ratio of the new nucleus is preferably 10% or less, more preferably 1% or less, and still more preferably 0.1% or less. PAg of the solution during particle growth,
By selecting pH, temperature, supersaturation concentration and the like, the growth ratio of tabular grains in the thickness direction and edge direction can be selected. In general, the growth rate in the thickness direction increases as the distance from the equivalent point increases, and as the concentration of the AgX solvent coexisting increases. On the other hand, when growing near the equivalence point under a low degree of supersaturation, growth occurs preferentially in the edge direction. Here, the low degree of supersaturation is 70% or less of the critical addition rate, preferably 5 to 5%.
It refers to a state in which addition is performed at an addition rate of 0%. The critical addition rate refers to an addition rate at which a new nucleus starts to form when a solute is added at a higher addition rate.

To control the degree of supersaturation during grain growth, Ag
⁺ Salt and X ^- can be increased with respect to the addition time of addition rate of the salts. In addition, a combination method of the above-mentioned fine particle addition method and ionic solution addition method can be mentioned. Details of these addition methods are described in JP-A-2-14633 and JP-A-3-213.
No. 39, No. 3-246534, Japanese Patent Application No. 2-36222
Nos. 2 and 3-36582 can be referred to. In the present invention, an AgX solvent can coexist during nucleation, ripening and crystal growth. Examples of the AgX solvent include ammonia, thioethers, thioureas, thiocyanates, organic amine compounds, antifoggants such as tetrazaindene compounds, and the like. be able to. The coexistence amount of the AgX solvent is 0 to 0.3 mol / l.

By utilizing the above-mentioned growth characteristics, the core tabular grains can be grown only in the edge direction, in the thick direction, or in both directions, so that grains having the structure shown in FIG. 1 can be separately formed. . In order to increase the selective growth in the edge direction and the thickness direction, a crystal growth controlling agent can be made to coexist at the time of crystal growth. Examples of the crystal growth controlling agent include photographic spectral sensitizing dyes and antifoggants. Preferred compounds can be selected according to a trial and error method and used at a preferred concentration. The concentration is usually 10 ^-6 mol / l or more, preferably 10 ^-5 to 1.
A preferred concentration can be selected and used in the range of 0 ^-2 mol / liter.

All of the methods for producing the tabular grains described in the above-mentioned conventional methods disclose a production method only by a nucleation → ripening step. In this case, the yield of AgX / batch becomes low, and the particle size of the obtained AgX particles cannot be freely controlled. However, when the tabular core grains are grown under normal crystal growth conditions (the solute is added by the above-mentioned solute addition method under the condition of pBr <2), four corners of the tabular grains fall,
It grows in the thickness direction and eventually becomes octahedral particles. Therefore, the particles of the present invention cannot be obtained. In order to obtain the tabular grains of the present invention, it is necessary to grow crystals with pBr of 2.3 or more and pAg of 2.3 or more. Preferably pAg 2.6 or more, p
It is necessary to grow with Br2.6 or more. However, Cl-
Excess ion concentration is preferably from ^{10 -1.2} mol / l ^or less, more preferably ^{10 -1.5} mol / l. For example, in the case of AgCl nuclei, a Cl ^- excess ion concentration of ^10-1.5 mol / liter is acceptable. It is preferable that the tabular grains grow under 50% or more, preferably 80% or more, more preferably 90% or more of the crystal growth volume under the above conditions. In this case, in order to obtain the tabular grains having a high aspect ratio, it is necessary to use a solute addition method as a fine grain emulsion addition method. Here, the fine particles refer to AgX fine particles having a diameter of 0.15 μm or less, preferably 0.1 μm or less, and more preferably 0.06 to 0.006 μm. Solution conditions are the same as the growth conditions. The above description can be referred to for other details of the fine particle addition method.

The nucleation conditions and ripening conditions in these cases can be referred to the above description. That is, the Br ^- concentration in the dispersion medium solution at the time of nucleation is preferably 10 ^-2.3 mol / L or less, more preferably 10 ^-2.6 mol / L or less. The Ag ⁺ concentration is preferably at least 10 ⁻⁴ mol / l, more preferably 10 ^−3.7 to 10 ^−1.5 mol / l, even more preferably 10 ^−3.4 to 10 ^−1.5 mol / l. Ag ⁺ and Br ^- concentrations of the solution during aging are 10
^It is preferably at most ^-2.3 mol / l, more preferably at most 10 ^-2.6 mol / l. Ag produced by the production method
X emulsion grains account for at least 20%, preferably 5%, of the total projected area.
0% or more, more preferably 80% or more has a principal plane of $ 10
The aspect ratio on the 0 ° plane is 1.3 or more, preferably 2 or more, more preferably 3 to 20, and even more preferably 4 to 16.
Are occupied by tabular grains. The particle size of the tabular grains is 1
0 μm or less, preferably 0.15 to 5 μm, more preferably 0.2 to 3 μm. The particle volume distribution of the particles is preferably monodisperse, and the coefficient of variation of the volume distribution is 4
It is preferably 0% or less, more preferably 30% or less, and 20% or less.
% Is more preferable. The halogen composition of the whole grain is Ag
Cl and AgBrI (I ^- content is 10 mol% or less, preferably 7 mol% or less) and a mixed crystal of two or more thereof.
However, Cl ^- content: preferably 49 mol% or less, more preferably 40 mol% or less, still more preferably not more than 20 mol%.

The shape of the principal plane is a right-angled parallelogram, or a shape in which the corners of the right-angled parallelogram are missing. There are four corners that are missing symmetrically and those that are missing asymmetrically.
The length of the corner missing portion is 1/3 or less, preferably 1/5 or less, of the length of one side of the quadrilateral when the straight line portion of the side is extended. 70% or more, preferably 80% of the particle surface of the particles
More preferably, 90% or more are {100} planes. Such particles are usually obtained near equal concentrations of Ag ⁺ and X ⁻ . The equilibrium crystal habit when ripening is continued under certain solution conditions is determined by the balance between the number of ions / second supplied to the particle surface by random walking and the number of ions / second desorbing from the particle surface into the solution. . A
In the case of gX particles, (the supply rate of Ag ⁺ to the particle surface ≒ the desorption rate of Ag ⁺ from the particle surface), (X ⁻ to the particle surface)
Desorption rate) equilibrium crystal habit is determined by the conditions are met ^- X from feed rate ≒ particle surface. In the case of the AgBr {100} plane, (the desorption speed of Ag ⁺ from the particle surface) ≒ (the desorption speed of X ⁻ from the particle surface), (the supply speed of Ag ⁺ to the particle surface ≒ the particle speed) The equilibrium solution condition is a solution condition (the rate of supply of X ⁻ to the surface) (because the diffusion coefficients of Ag ⁺ and X ⁻ are almost equal, the vicinity of an equal concentration of Ag ⁺ and X ⁻ ). On the other hand, in the case of AgBr {111} plane, ^<- for a (Br from the particle surface desorption rate of, (Br ^- concentration Ag ⁺ desorption rate of from the particle surface)> Ag ⁺ concentration) solution conditions of And equilibrium. Since I ⁻ has a large van der Waals force and is difficult to desorb, the {100} equilibrium crystal habit of AgBrI is obtained under the condition of (Ag ⁺ concentration> X ⁻ concentration). A
When the gX solvent is added (Ag ⁺ concentration <Br ^- concentration)
, The (Ag ⁺ concentration + Ag ⁺ complex concentration) ≒ Br ⁻ concentration, and the equilibrium crystal habit is a {100} plane. On the other hand, the equilibrium crystal habit in the case of crystal growth is determined by the relative growth rate ratio between the {100} plane and the {111} plane. However, when grown with low supersaturation, the shape is close to the ripening equilibrium.

(D) Others The following description can be referred to in addition to the above (A) to (C). The obtained particles may be used as host particles to form epitaxial particles. Further, particles having dislocation lines therein may be formed using the particles as a core. Alternatively, the particles may be used as a substrate, and AgX layers having a different halogen composition from the substrate may be laminated to produce various known particles having various particle structures. Regarding these, the description in the following literature can be referred to. Further, a chemically sensitized nucleus is usually provided to the obtained emulsion grains.

In this case, the location and number /
Preferably, cm ² is controlled. Regarding this, JP-A-2-828 and JP-A-2-14633, Japanese Patent Application No.
Nos. 73079 and 3-73266 can be referred to. Further, a shallow inner latent emulsion may be formed using the tabular grains as a core. Also, core / shell type particles can be formed. About this,
Nos. 9-133542 and 63-151618, U.S. Pat. Nos. 3,206,313 and 3,317,322,
Nos. 3,761,276, 4,269,927, and 3,367,778 can be referred to. The AgX emulsion grains produced by the method of the present invention can be used by blending with one or more other AgX emulsions.
The blend ratio can be appropriately selected and used within the range of 1.0 to 0.01.

The pH of the reaction solution in the steps (B) and (C) can be usually selected from the most preferable values in the range of 1 to 12, preferably 2 to 11. There are no particular restrictions on the additives that can be added to these emulsions during the period from the grain formation to the coating step, and any conventionally known photographic additives can be added. For example, an AgX solvent, a doping agent for AgX particles (eg, a Group 8 noble metal compound, another metal compound, a chalcogen compound, an SCN compound, etc.), a dispersion medium, an antifoggant, a sensitizing dye (blue, green, red, infrared) , Panchromatic, orthorectified, etc.), supersensitizers, chemical sensitizers (sulfur, selenium, tellurium, gold and Group 8 noble metal compounds, phosphorus compounds, rhodan compounds, reduction sensitizers alone or two or more thereof) ), Fogging agents, emulsion precipitants, surfactants, hardeners, dyes, color image forming agents, color photographic additives,
Examples include soluble silver salts, latent image stabilizers, developers (hydroquinone compounds and the like), pressure desensitizing inhibitors, matting agents and the like.

The AgX emulsion particles of the present invention and the AgX emulsion produced by the production method can be used for all conventionally known photographic light-sensitive materials. For example, a black-and-white silver halide photographic light-sensitive material (for example, X-ray light-sensitive material, printing light-sensitive material, photographic paper,
Negative film, microfilm, direct positive photosensitive material, ultra fine particle dry plate photosensitive material (for LSI photomask, shadow mask, liquid crystal mask)], color photographic photosensitive material (for example, negative film, photographic paper, reversal film, direct positive color feeling) Materials, silver dye bleaching photography, etc.). Further, a diffusion transfer type photosensitive material (for example, a color diffusion transfer element,
(Silver salt diffusion transfer element), photothermographic materials (black and white, color), high-density digital recording materials, holographic materials, and the like.

The amount of silver to be coated can be selected to a preferable value of 0.01 g / m ² or more. The composition of the photographic material (eg, layer composition, silver / coloring material molar ratio, silver ratio between layers, etc.);
There are no restrictions on the exposure, development processing, the apparatus for producing a photographic light-sensitive material, the emulsification and dispersion of photographic additives, and any other conventionally known modes and techniques can be used. For the conventionally known photographic additives, photographic light-sensitive materials and their constitutions, exposure and development processing, photographic light-sensitive material manufacturing equipment, etc., the description in the following documents can be referred to.

[0033] Research D
isclosure), 176 volumes (item 17643) (12
Mon, 1978), Volume 307 (Item 30710)
May and November, 1989), by Duffin, Photographic Emulsion Chemistry, Foca.
l Press, New York (1966), by Bill (EJ Bi
rr), stabilization of photographic silver halide emulsions (Stabilizatio
n of Photographic SilverHalide Emulsions, Focal Press, London (1974)
Year), James James (TH James), The Theory of Photographic Process, 4th Edition, Macmillan, New York (1977)

[0034] P. Glafkides, Chemie et Physique Photographiques, 5th ed., Edition de Linginevel
l ', Usine Nouvelle, Paris (1987), 2nd edition,
Paul Montel, Paris (1957), VL Zelikman et al., Preparation and coating of photographic emulsions (Ma
king and Coating Photographic Emulsion), Focal Pr
ess (1964), KR Hollister, Journal of Imaging Science (Journal)
of Imaging science), vol. 31, p. 148-156
(1987), JE Maskasky, pp. 30, p. 247-254 (1986), 32
Vol. 160-177 (1988), Vol. 33, No. 10
13 (1989),

Ed. Freezer et al., Basics of the Silver Halide Photography Process (Die Grundlagen Der Photographischen Prozesse)
Mit Silverhalogeniden), Akademische Verlaggesellschaf
t), Frankfurt (1968). JCIA Monthly Report 19
1984, December issue, p. 18-27, Journal of the Photographic Society of Japan,
49, 7-12 (1986), 52, 144-
166 (1989), 52, 41-48 (198
9), JP-A-58-113926 to JP-A-13928, JP-A-59-90841, JP-A-58-111936, and 62.
No. 99751, No. 60-143331, No. 60-1
No. 43332, No. 61-14630, No. 62-625
No. 1, 63-220238, 63-151618
Nos. 63-281149 and 59-133542
No. 59-45438, No. 62-269958,
No. 63-305343, No. 59-142439, No. 62-253159, No. 62-266538, No. 6
Nos. 3-107813, 64-26839 and 62-
No. 157024, No. 62-192036,

JP-A-1-297649 and 2-127
No. 635, No. 1-158429, No. 2-42, No. 2
No. -24643, No. 1-146033, No. 2-838
No. 2-28638, No. 3-109539, No. 3
-175440, 3-121443, 2-73
No. 245, No. 3-119347, U.S. Pat.
6,461, 4,942,120, 4,26
9,927, 4,900,652 and 4,97
5,354, European Patent No. 0355568A2, Japanese Patent Application Nos. 2-326222, 2-415037, and 2-
No. 266615, 2-43691, 3-1603
No. 95, No. 2-142635, No. 3-146503
issue,

[0037]

Next, the present invention will be described in more detail by way of examples, but embodiments of the present invention are not limited thereto. Example 1 A gelatin solution-1 [CH ₂ 01200 cc) was placed in a reaction vessel.
24 g of deionized alkali-treated bone gelatin, KNO
₃ (1N) containing 5 cc, pH with HNO ₃ (1N) solution
4.0 and the temperature was kept at 40 ° C. While stirring, 15 cc of an AgNO ₃ -1 solution ( ₃ g of AgNO 3/100 cc) was added, and after 5 minutes, an aqueous solution of Ag-1 (AgNO ₃ ) was added.
20 g / 100 cc) and its equimolar concentration of X-1
48 c of an aqueous solution (KBr: KI = 98.5: 3 molar ratio)
The mixture was added at a rate of c / min for 1 minute with a precision liquid feed pump. After stirring for 1 minute, the pH was adjusted to 6.2 using an HNO ₃ solution and a KOH solution, and further, an AgNO ₃ -1 solution and KBr-
Using one solution (KBr 3 g / 100 cc), the silver potential was increased to 16
Adjusted to 0 mV (vs. room temperature calomel electrode). Then 1
The temperature was raised to 75 ° C. in 0 minutes and aged for 30 minutes. The results obtained from transmission electron micrograph images (hereinafter, referred to as TEM images) of replicas of the emulsion grains sampled at this time were as follows. The principal plane is a {100} plane, the shape of the principal plane is a rectangular parallelogram, and the projected area ratio of grains having an aspect ratio of 1.3 or more (hereinafter referred to as tabular grains A) is about 92.
%, Its average projected particle diameter was 0.62 μm, the average aspect ratio was 4.77, and the variation coefficient of the particle size distribution was 32%.

Next, 3 cc of an aqueous solution of NH ₄ NO ₃ -1 (50% by weight) and 3 cc of an aqueous solution of NH ₃ -1 (25% by weight) were added, and fine particles of AgBr having an average particle size of 0.035 μm were further added.
0.06 mol of an I (I ^- content: 1.5 mol%) emulsion was added, and the mixture was further ripened at a silver potential of 150 mV for 18 minutes. Further, 0.08 mol of the same fine grain emulsion was added and ripened for 18 minutes.
After repeating the addition of 0.1 mol of the same fine grain emulsion and aging for 18 minutes twice, a sedimentation agent was added, the temperature was lowered to 30 ° C., and water was washed by sedimentation washing. An aqueous gelatin solution was added, and the emulsion was redispersed and adjusted to pH 6.4 and pBr 2.8. The following results were obtained from TEM images of the obtained emulsion grains. The projected area ratio of the tabular grains A was 92%, the average projected particle size was 1.4 μm, the average aspect ratio was 7.7, and the variation coefficient of the grain size distribution was 31%. The I ^- content at the center of the particles is 3 mol%, and the I ^- content at the shell is 1.5 mol%.

Example 2 A gelatin solution-1 was placed in a reaction vessel and the temperature was kept at 40 ° C. While stirring, 10 cc of AgNO ₃ -1 solution was added, and 5
Minutes later, an aqueous solution of Ag-1 and an equimolar concentration of X-1
-2 aqueous solution (KBr: KI = 98.5: 1.5 molar ratio)
Was added at a flow rate of 48 cc / min for 1 minute using a precision liquid feeding pump. After stirring for 1 minute, the pH was adjusted to 6.1 with HNO ₃ solution and KOH solution, and further, AgNO ₃ -1 solution and KB
Silver potential was adjusted to 160 mV using r-1 solution. Next, the temperature was raised to 75 ° C. in 10 minutes and aged for 30 minutes. Next, 5 cc of NH ₄ NO ₃ aqueous solution-1 (50% by weight)
After adding 5 cc of ₃ aqueous solution-1 (25% by weight), Ag-
2 aqueous solution (AgNO ₃ 10 g / 100 cc) and X-2 aqueous solution (containing 6.8 g of KBr and 0.294 g of KI in 100 cc) while keeping the silver potential at 120 mV.
J. (Controlled double jet) was added. The initial flow rate was 10 cc / min, and 570 cc was added by a linear flow rate acceleration addition method of 0.05 cc / min. After stirring for 2 minutes, the temperature was lowered to 30 ° C., and the resultant was washed with water by a sedimentation washing method. Add gelatin aqueous solution,
The emulsion was redispersed and adjusted to pH 6.4, pBr 2.8. The following results were obtained from the TEM image of the replica of the obtained emulsion grains. The projected area ratio of the tabular grains A is about 93%, the average projected grain size is 1.2 μm, the average aspect ratio is 4.9,
The coefficient of variation of the particle size distribution was 28%. The particles are core / shell particles and the core layer has an I ^- content of 1.5
In mol%, the I ^- content of the shell layer is 3 mol%.

Example 3 The core particle formation was the same as in Example 1. Next, NH ₄ NO
₃ -1 aqueous 5cc, after addition 5cc the NH ₃ -1 aqueous silver potential 12 by using the aqueous solution Ag-2 and X-2 aqueous solution
CDJ was added while maintaining the voltage at 0 mV. Initial flow rate is 1
At a rate of 1.0 cc / min, 570 cc was added by a linear flow rate acceleration addition method of 0.05 cc / min. After stirring for 2 minutes, the temperature was lowered to 30 ° C., and the resultant was washed with water by a sedimentation washing method. Add gelatin aqueous solution,
The emulsion was redispersed and adjusted to pH 6.4, pBr 2.8. The following results were obtained from the TEM image of the replica of the obtained emulsion grains. The projected area ratio of the tabular grains A is about 92%, the average projected grain size is 1.18 μm, and the average aspect ratio is 4.
7. The variation coefficient of the particle size distribution was 30%. The I ^- content in the center of the particles was 3 mol%, and the I-
^The content is also 3 mol%;

Example 4 A gelatin solution-2 [1200 cc of H ₂ O, e
mpty contains 12 g of alkali-treated bone gelatin, 12 g of non-deionized same gelatin, 5 cc of KNO ₃ (1N),
PH was adjusted to 5.5 with a KOH (1N) solution] at 40 ° C.
To constant temperature. 33cc of AgNO ₃ -1 solution while stirring
5 minutes later, Ag-1-4 solution [Ag in 100 cc
20 g of NO ₃ , 1 g of gelatin, HNO ₃ (1N) solution
25cc) and X-1-4 aqueous solution [K in 100cc
Br14g, gelatin 1g, KOH (1N) 0.25c
c) at 48 cc / min for 1 minute using a precision liquid sending pump. After stirring for 1 minute, the pH was adjusted to 6.1 and A
The silver potential was set to 150 using the gNO ₃ -1 solution and the KBr-1 solution.
Adjusted to mV. Then raise the temperature to 75 ° C in 10 minutes,
Aged for 20 minutes. The observation result of the TEM image of the replica of the emulsion grains sampled at this time was as follows.

The projected area ratio of the tabular grains A is about 95%, the average projected grain size is 0.75 μm, the average aspect ratio is 6.5,
The coefficient of variation of the particle size distribution was 33%. Next, NH
₅ NO ₃ -1 aqueous solution 5 cc, NH ₃ -1 aqueous solution 5 c
After the addition of C.c, while maintaining the silver potential at 120 mV using an aqueous solution of Ag-2 and an aqueous solution of X-2, C.I. D. J. Was added.
The initial flow rate was 9 cc / min, and 570 cc was added by a linear flow rate acceleration addition method of 0.05 cc / min. After stirring for 2 minutes,
The temperature was lowered to 30 ° C., and water was washed by a sedimentation precipitation method. An aqueous gelatin solution was added and the emulsion was redispersed, pH 6.4, pBr2.
Adjusted to 8. The following results were obtained from the TEM image of the replica of the obtained emulsion grains. The projected area ratio of the tabular grains A was about 95%, the average projected grain size was 1.34 μm, the average aspect ratio was 5.36, and the variation coefficient of the grain size distribution was 30%. The I-content of the central part of the grains is 0 mol%, and the I ^- content of the shell layer is 3 mol%, which is a tabular grain of type (1) in FIG.

Example 5 The procedure was the same as in Example 4, except that the AgBr core particles were prepared. Next, 0.06 mol of an AgBr fine particle emulsion (having a particle size of 0.04 μm) was added, and ripening was performed at a silver potential of 150 mV for 25 minutes. Further, 0.06 mol of the fine grain emulsion was added, and the mixture was aged for 25 minutes. Then, 5 cc of an aqueous NH ₄ NO ₃ -1 solution was added.
₃ -1 solution was added 5 cc, the silver potential and 220 mV,
Using the aqueous solution of Ag-2 and the aqueous solution of X-2,
J. Added. The initial flow rate was 9 cc / min, and 200 cc was added by a linear flow rate acceleration addition method of 0.05 cc / min. After stirring for 2 minutes, the temperature was lowered to 30 ° C., and the resultant was washed with water by a sedimentation washing method. An aqueous gelatin solution was added, and the emulsion was redispersed, pH 6.4, p.
Br was adjusted to 2.8. The following results were obtained from the TEM image of the replica of the obtained emulsion grains. The projected area ratio of the tabular grains A is about 95%, the average projected grain size is 1.32 μm, the average aspect ratio is 6.87, and the variation coefficient of the grain size distribution is 3
1%. The I ^- content at the center of the particles is 0 mol%,
The shell layer had an I ^- content of 3 mol%, and was tabular grains of the type (5) in FIG.

Example 6 The procedure was the same as in Example 4 until the AgBr core particles were prepared. Next, an aqueous solution of Ag-2 and an aqueous solution of X-2-6 (KBr
0.14 g / cc) at a silver potential of 180 mV
Was added. The initial flow rate was 12 cc / min, and 300 cc was added by a linear flow rate acceleration addition method of 0.1 cc / min. Next, the silver potential was set to 150 mV, 0.1 mol of a fine grain AgBrI (I ^- content: 2 mol%, average particle size: about 0.033 μm) emulsion was added, the mixture was aged for 25 minutes, then cooled to 30 ° C., and washed by settling. Washed with water. An aqueous gelatin solution was added, and the emulsion was redispersed and adjusted to pH 6.4 and pBr 2.7. The following results were obtained from the TEM image of the replica of the obtained emulsion grains.
The projected area ratio of the tabular grains A was about 95%, the average projected grain size was 1.15 μm, the average aspect ratio was 5.75, and the variation coefficient of the grain size distribution was 30%. I at the center of the particle
^The content was 0 mol% and the I ^- content of the shell layer was 2 mol%, and the particles were tabular grains of the type (3) in FIG. (Preparation of fine grain emulsion) AgBrI (I ^- content 1.5
Mol%), AgBr and AgBrI (I ^- content: 2 mol%) fine grain emulsion, JP-A-2-146033, the 4-
It was prepared with reference to the description of 34544. That is, in a reaction vessel, an aqueous gelatin solution (1200 g of water, 24 g of deionized alkali-treated gelatin having an average molecular weight of 30,000, KBr0.
6 g), maintain at 22 ° C. and stir with A
It was prepared by adding a gNO ₃ solution (AgNO ₃ 0.3 g / cc) and an X ^- salt solution (0.1773 mol / 100 cc) at 90 cc / min for 3 minutes.

Comparative Example 1 The core particles were formed in the same manner as in Example 4. Next, Ag-2-
4 aqueous solution _{(AgNO 3 15g / 100cc) X} -2-
4 Using aqueous solution (KBr 10.5 g / 100 cc)
At 5 ° C., an initial flow rate of 9 cc / min and a linear flow rate accelerated addition method of 0.05 cc / min. D. J. Was added. After stirring for 2 minutes, the temperature was lowered to 30 ° C., and the resultant was washed with water by a sedimentation washing method. An aqueous gelatin solution was added, and the emulsion was redispersed and adjusted to pH 6.5 and pBr 2.8. According to the result of the TEM image of the replica of the obtained emulsion particles, the average projected particle diameter was 1.33 μm, the average aspect ratio was 5.4, and the variation coefficient of the particle size distribution was 30%, which were almost the same as those in Example 4. .

Comparative Example 2 The core particles were formed in the same manner as in Example 4. Next, Ag-2-
Using the 4 aqueous solution and the X-2-4 aqueous solution, 385 cc of CDJ was added at 75 ° C. at an initial flow rate of 7.5 cc / min and a linear flow rate accelerated addition method of 0.05 cc / min at a silver potential of 160 mV. After stirring for 2 minutes, the temperature was lowered to 30 ° C., and the resultant was washed with water by a sedimentation washing method. Add gelatin aqueous solution, redisperse emulsion,
The pH was adjusted to 6.4 and pBr 2.8. According to the result of the TEM image of the replica of the obtained emulsion grains, the average projected particle size is 1.38 μm, the average aspect ratio is 7.8, and the variation coefficient of the grain size distribution is 31%, which is almost the same as that of Example 1. Was. The emulsions obtained in Examples 1 and 4 and Comparative Examples 1 and 2 were heated to 55 ° C., and Dye 1 was added at 70% of the saturated adsorption amount.

[0047]

Embedded image

Hypo was added at a rate of 2 × 10 ⁻⁵ mol / mol AgX, and after 5 minutes a gold sensitizer [chloroauric acid: NaSC
N = 1: 50 molar ratio aqueous solution] in 1 × 10 ⁵ mol /
Only the mole AgX was added, and the temperature was lowered to 40 ° C. after 30 minutes.
Next, an antifoggant TAI (4-hydroxy-6-m
ethyl-1,3,3a, 7-tetraazain
after adding 2 × 10 ⁻³ mol / mol AgX, a thickener (sodium poly-p-styrenesulfonate) and a coating aid (sodium dodecylbenzenesulfonate) were added. cellulose)
On the base, a silver amount of 1 g / m ² was applied together with a protective layer. Pass each coated sample through a minus blue filter for 10
-Wedge exposure for ² seconds, MAA-1 developer ("J
ournalof Photographic Sci
ence, vol. 23, pages 249-256, 1975) at 20 ° C. for 10 minutes. Further, the solution was passed through a stop solution, a fixing solution, and a washing solution to be dried. The results of the photographic characteristics were as follows. Comparative Example 1 (relative sensitivity 100, graininess 1
00), as compared with Example 4 (relative sensitivity 115, granularity 9
3) and Comparative Example 2 (relative sensitivity 105, granularity 97), and Example 1 (relative sensitivity 121, granularity 90). Therefore, in comparison with Comparative Examples 1 and 2, which are conventional emulsions,
It was confirmed that Examples 1 and 4 were superior in sensitivity and granularity. Further, the superiority of the emulsion of Example 1 having a high I ^- content at the center was confirmed. The RMS granularity is determined by uniformly exposing the sample to an amount of light that gives a density of 0.2 above the fog, and after performing the above-described development processing, James ed., The Theory of the Photographic Process, 21 Measured as described in Chapter (1977). In each case, the comparative sample was relatively expressed as 100.

[0049]

The conventional AgX containing {100} tabular grains
An AgX emulsion having improved sensitivity and image quality as compared with an emulsion can be provided. Further, it is possible to provide a method for producing an AgX emulsion in which sensitivity and image quality can be freely controlled.

[Brief description of the drawings]

FIG. 1 shows examples of the grain structure (1) to (8) of the core / shell type tabular grains according to claim 1. The layer a core layer, b layer I than the core layer ^- a high content: layer, c layer I than b layer ^-
3 shows a layer with a low content.

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

Claims (2)

(57) [Claims] (1) The total projected area of the silver halide emulsion grains is 2
0% or more has a {100} principal plane and an aspect ratio of 1.
Produce a silver halide emulsion that is three or more tabular grains
In the method, the tabular grains have an iodine content at the center of the grains.
A tabular grain or core layer having a content of 1.2 mol% or more;
A shell layer, at least one iodine of the shell layer
Flat plate whose content is 20% or more higher than the iodine content of the core layer
Grains, and the production method comprises at least a silver halide nucleus.
It is manufactured through the process of formation, ripening, and crystal growth.
And the nucleation is at a Br ion concentration of 10
^{-At a rate of} not more than ^2.3 mol / l,
Both the Ag ion concentration and the Br ion concentration
10 ^-2.3 JP to be performed in the following mole / liter
And a method for producing silver halide emulsion grains. 2. The solution condition during the crystal growth is Ag ion concentration.
Degree and Br ion concentration are both ^10-2.3 mol / ^l
C and a particle size of 0.15 μm or less.
It is characterized by being performed by the addition of silver logenide fine particles.
The method for producing silver halide emulsion grains according to claim 1.