JPH10177227A - Manufacture of silver halide emulsion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing the silver halide good in monodispersibility and controlling silver halide composition and an aspect ratio and improving sensitivity, sharpness, graininess characteristics, resolution, and image quality. SOLUTION: The silver halide emulsion containing flat silver halide grains good in monodispersibility and containing 70-100% of the projection areas of the total silver halide grains can be obtained by forming silver halide nuclei at 5-30 deg.C in a pBr of 1.0-2.5 and in an I<-> content of <=31.2+0.165×(t-25)mol% in the nuclei, (t being a nucleus forming temperature), and executing Oswald ripening at 45-80 deg.C in order to eliminate nonflat grains and to enhance their projection areas and carrying out grain growth.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a silver halide emulsion.

[0002]

2. Description of the Related Art Tabular silver halide grains having parallel twin planes (hereinafter referred to as "tabular grains") have the following photographic properties: 1) their specific surface area is large, and a large amount of sensitizing dye is adsorbed on the surface. (2) When the emulsion containing tabular grains is coated and dried, the grains are arranged in parallel to the base surface, so that the coated layer has a high sensitivity of -blue (blue) / blue (blue). 3) In a radiographic system, when a sensitizing dye is added to tabular grains, the extinction coefficient of the dye is larger than that of the indirect transition of silver halide (AgX). And 4) when developing tabular grains having a high aspect ratio, the covering power is high, and the silver density and the dye density are low. 5) tabular grains having parallel multiple twins are liable to form a latent image in the edge trough portion thereof, dispersal of the latent image is prevented, and 6) light scattering is achieved. There are few advantages, such as obtaining an image with high resolution, and the like, and since it has many advantages, it has been used as a high-sensitivity commercially available photosensitive material.

Recently, Eastman Kodak Company disclosed emulsion grains having a flatter aspect and an aspect ratio of 8 or more as compared with conventional ones (for example, Japanese Patent Application Laid-Open No. 58-1983).
113926, 58-113927, 58-1
No. 13928). In these claims, it is indicated in the claims that the diameter is 0.6 μm or more and the average aspect ratio is 8 or more. However, most of the tabular grains used in the examples have a diameter (average). AgBrI emulsion having an average particle diameter of 0.8 μm is shown in only one case. However, even in that case, the total projected area ratio of the tabular grains is only 55%, and it can be said that the emulsion is a thin emulsion having characteristics as tabular grains. Also, looking at the photographs of the emulsion grains, including large tabular grains,
Monodispersity is poor. In an emulsion containing tabular grains having such a large size, deterioration of graininess, deterioration of sharpness, and the like occur.

Further, when an emulsion in which large grains and small grains are mixed is chemically sensitized, the optimum conditions for the chemical sensitization are different between the large grains and the small grains. There is a problem that it is difficult.

Further, tabular grains having an aspect ratio of 20 or more tend to break during stirring during the preparation of the emulsion, or to break when subjected to pressure or physical impact on the film in the coated and dried state, so-called poor pressure resistance. It is inconvenient.

The advantages described in the above 1) to 6) occur when the proportion of tabular grains occupies a high level. Such advantages are exhibited even when the average grain size is 0.1 to 1.0 μm. . Furthermore, the light scattering efficiency factor (Qsc
a) is particularly large in the case of cubic grains having a size of 0.3 to 0.6 μm, but when high aspect ratio tabular grains are oriented parallel to the base, tabular grains having an average grain size of 0.3 to 0.6 μm. It is predicted from Mie's scattering theory that the light scattering efficiency factor of the particle-shaped particles is smaller than that of the cubic particles.

In view of these points, the fine particles having an aspect ratio of 2 to 20, particularly 4 to 16, having a narrow particle size distribution (for example, a coefficient of variation of 30% or less), and the proportion of tabular grains Is desired (for example, 60% or more), but the production method is not yet clear.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to improve sensitivity, sharpness, granularity, resolution, and image quality with good monodispersity and control of halogen composition and aspect ratio. It is another object of the present invention to provide a method for producing a silver halide emulsion which can perform the following.

[0009]

This and other objects are achieved by the present invention described below. (1) A method of producing a silver halide emulsion containing 70 to 100% of the total projected area of tabular silver halide grains having good monodispersity by undergoing nucleation, Ostwald ripening and grain growth of the silver halide grains. In the above, the nucleation was carried out under the conditions of a temperature of 5 to 30 ° C. and a pBr of 1.0 to 2.5, and the I ⁻ content in the nucleus was [31.2 + 0.165 (t−
25) mol% (t: nucleation temperature)] or less, wherein the Ostwald ripening is carried out at 45 to 80 ° C. to eliminate non-tabular grains and increase the total projected area ratio of tabular grains. Method for producing silver halide emulsion.

[0010]

According to the present invention, nucleation is carried out in an aqueous solution containing a dispersion medium at a temperature of 5 to 30 ° C. and a pBr of 1.0 to 1.0.
In this case, at least 70% or more of the total projected area of the silver halide grains is tabular grains having a diameter of 0.15 μm or more, and the average aspect ratio of all the tabular grains is not less than 2.5%. The ratio is 2 to 20, the average particle size is 0.6 μm or less, and the coefficient of variation is 3
0% or less of silver iodobromide emulsion or silver chloroiodobromide emulsion (C
1 content is 30 mol% or less).

The above tabular grains can be used as a core for shelling, and the halogen composition and aspect ratio can be controlled.

By using such an emulsion, sensitivity, sharpness, granularity, resolution and image quality can be improved.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a specific configuration of the present invention will be described in detail. Silver halide of the present invention (AgX)
The method for producing an emulsion involves Ostwald ripening and grain growth following nucleation of silver halide grains. This method
JP-A-51-39027 and JP-A-55-142329
No. is described in Examples.

In the present invention, the above three steps are independent and of a function-separated type.

In such a production method, nucleation is preferably carried out with an aqueous solution containing a dispersion medium. Gelatin is used as the dispersion medium, and the temperature of the aqueous gelatin solution at the time of nucleation is 5 to 39 ° C., preferably 5 to 39 ° C. To 30 ° C., particularly preferably 10 to 30 ° C., and the pBr in the aqueous gelatin solution is set to 1.
Keep at 0-2.5. When unmodified gelatin or the like is used as the gelatin, the concentration of the gelatin aqueous solution is adjusted to 0.0
More preferably, the content is 5 to 2% by weight, and more preferably 0.05 to 1.6% by weight.

In the present invention, at the time of nucleation, 5 to 30 ° C.
Use low temperature. The first reason is that, as described in JP-A-58-113926, JP-A-58-113927 and JP-A-58-113228, for example.
This is because the generation probability of tabular grains becomes extremely high as compared with the nucleation of tabular grains at -80 ° C.

[0017] In the nucleation performed in conventional 40 to 80 ° C., in order to increase the proportion of tabular grains formed during nucleation, Br ^- it is performed to increase the concentration, Br ^- Increasing the concentration, bi The proportion of grains without crystal planes decreases, but the proportion of nonparallel multiple twin grains increases, and the tabular grain proportion of the resulting emulsion is less likely to increase. If the tabulation ratio is forcibly increased, the resulting particles will contain large tabular grains, and fine particles having a high tabularization ratio cannot be obtained. However, when the method of the present invention is used, tabular grains which are fine particles, have a high tabularization rate, and have good monodispersity can be obtained. The lower the temperature, the higher the flattening rate. However, if the temperature is too low, the gelatin aqueous solution gels. Therefore, the temperature is preferably in the range of 5 to 30C, particularly 10 to 30C.

The second reason for using a low temperature is that Ostwald ripening does not occur during the nucleation stage, and the nuclei of the tabular grains thus formed can be stably present.
Further, since the growth rate becomes very slow, generation of large nuclei as seen in the conventional method can be suppressed, and the size distribution of nuclear particles (nuclear particles generated during the nucleation phase) is narrowed. can do. In this case, the average particle size of the core particles is 0.2 μm or less, and moreover, the average particle size is 0.2 μm.
Fine particles of 10 μm or less can be obtained.

The third reason for using a low temperature is that the yield of tabular grain emulsion obtained when the same reaction vessel is used is high. In high-temperature nucleation, tabular grains generated early in the nucleation phase grow quickly and grow large in the late phase, so the nucleation period needs to be shortened. If a large amount of AgNO ₃ and an aqueous alkali halide solution are added in a short time, the ratio of multiple twin grains containing non-parallel twin planes increases, and a large amount of AgNO ₃ and an alkali halide cannot be added. On the other hand, at a low temperature, the tabular grains generated in the early stage of the nucleation period do not grow rapidly, so that the nucleation period can be made longer. Therefore, a larger amount of AgNO ₃ and an alkali halide can be added without increasing the ratio of multiple twin grains containing non-parallel twin planes, and therefore, a flat plate obtained using the same reactor can be obtained. The yield of the grain emulsion can be increased.

The reason for setting pBr to 1.0 to 2.5 is that pB
When r is less than 1.0, incorporation of non-parallel twins is caused, and Ag
It is not preferable that the solubility of Br becomes too high and that the amount of AgNO _{3 to} be added to reduce the Br ⁻ concentration increases during the transition to the next ripening step.

On the other hand, when the value of pBr exceeds 2.5, the flattening rate is remarkably reduced, which is not preferable.

The essential conditions of the present invention are a low temperature of 5 to 30 ° C., preferably 10 to 30 ° C., and a pBr of 1.0 to 2.5.
Nucleation of tabular grains in an aqueous solution.

Further, a more preferable feature of the production method in the present invention is that the production method is carried out at a low temperature and a low concentration (for example, 0.05 to 2.0.
(0% by weight, preferably 0.05 to 1.6% by weight) nucleation of tabular grains in an aqueous gelatin solution.

In general, an aqueous solution having a gelatin concentration of 2.0 to 10% by weight is used, because the probability of forming tabular grains becomes extremely high as compared with such conditions. When unmodified gelatin is used, the gelatin concentration of the aqueous gelatin solution is particularly effective in the range of 0.05 to 2% by weight, particularly 0.05 to 1.6% by weight. The lower the gelatin concentration, the higher the probability of tabular grain formation, which is preferable. However, if the gelatin concentration is too low, the protective colloid property of the gelatin is reduced, and coalescence of the grains is caused, so that 0.05% by weight or less is not preferable.

When low molecular weight gelatin is used as the gelatin used for nucleation at a low temperature, the gelatin aqueous solution does not gel even at a low temperature, and nucleation with a small mixing ratio of non-parallel twin grains can be achieved. Therefore, it is more effective. In this case, the effective molecular weight of the low molecular weight gelatin is 2,000 to 100,000.

For example, an aqueous solution of 0.1 to 10% by weight of alkali-treated bone gelatin having a molecular weight of about 10,000 does not gel even at 0 ° C. In this case, the gelatin concentration of the aqueous gelatin solution is 0.1 to 2.0% by weight, particularly 0.05 to 1.6%.
The weight% region is effective, and the temperature of the reaction aqueous solution at the time of nucleation is 5 to 30 ° C, preferably 10 to 30 ° C.

Further, a feature of the production method of the present invention is that, in addition to the above conditions, modified gelatin obtained by acylating a free amino group of gelatin such as phthalated gelatin is used as gelatin. This is because the use of such a modified gelatin in the nucleation phase further increases the probability of forming tabular grains.

In this case, the concentration of gelatin in the aqueous gelatin solution is also 0.05 to 2.0% by weight, particularly 0.05 to 2.0% by weight.
The 1.6% by weight region is effective.

In the production method of the present invention, nuclei of tabular grains are formed in an aqueous gelatin solution at a low temperature. However, the use of the above-mentioned modified gelatin is more preferable because it is difficult to gel at a low temperature. For example, 1.0% by weight
When an aqueous solution of phthalated gelatin (phthalation rate: 90%) is used, gelation does not occur even at about 5 ° C., and nucleation of tabular grains can be performed effectively. Therefore, when phthalated gelatin is used at a low temperature and a low-concentration aqueous gelatin solution is used, a higher probability of producing tabular grains can be obtained without causing gelatinization of the aqueous gelatin solution in a wide low-temperature region up to about 5 ° C. Thus, tabular grains can be efficiently obtained.

In this case, the phthalation rate of the phthalated gelatin is effectively from 0 to 100%, but is theoretically 97.5%.
If the ratio is more than 0, the crosslinking point at the time of hardening disappears, so that 0 to 97.
5% is effective. The effect of increasing the flattening rate increases as the phthalating rate increases. Further, the effect of preventing the gelatin aqueous solution from gelling at a low temperature increases as the phthalation rate increases.

The modified gelatin is disclosed in US Pat. Nos. 2,614,928 and 2,614,929.
You can refer to what is described in the issue.

For unmodified gelatin, reference can be made to Research Disclosure Magazine, December, 1978, IX.

In the process for producing tabular silver halide grains, conventionally, the relationship between the reaction temperature and the distribution of the grain size (monodispersity) has not been known. It was found for the first time in the present invention that the lower the reaction temperature, the better the monodispersity. In particular, it has been found in the present invention that the monodispersibility of the tabular grains is improved by producing the dispersion medium at a low temperature as described above under the condition that the dispersion medium is as thin as 0.05 to 2.0 wt%. The effect is.

Certainly, those skilled in the art may try to change the reaction temperature during nucleation in obtaining tabular grains.

However, there has been no fact that tabular grains were actually produced at the reaction temperature of the present invention, and the monodispersity of the particles produced at the reaction temperature of the present invention is described in Example 11 below.
As can be seen from FIG. 5, it shows a clear improvement as compared with the conventional one, which is sufficiently satisfactory for practical use. And
As described above, the improvement of the monodispersity due to the decrease in the reaction temperature is an unexpected effect.

Therefore, in this sense, it can be said that the present invention cannot be predicted from the prior art.

In the production method of the present invention, in addition to the above conditions, when the pH of the aqueous gelatin solution is increased, the flattening rate is further increased. However, when the pH is set to 10 or more, fog nuclei are generated in the generated AgX particles, which is not good in photographic properties.

From the above, a pH range of 2 to 10 can be used.

Specifically, a water-soluble silver salt, in particular, an aqueous solution of AgNO ₃ and an aqueous solution of an alkali halide are double-jetted into a reaction vessel charged with a solution containing an alkali halide, water and gelatin (dispersion medium). The addition is performed under the conditions described above.

In this case, an essential condition of the solution to be charged in the reaction vessel in advance is that the Br ^- concentration is adjusted to pBr 1.0 to 2.5. Other, I ^- or Cl ^- can be added, I ^- preferably less 3 mol% as a content.

As described above, the gelatin concentration is, for example, 0.05 to 2.0% by weight, preferably 0.05 to 1.6%.
% By weight.

On the other hand, the AgN ₃ aqueous solution
The O ₃ concentration and the concentration of the aqueous alkali halide solution are preferably equal to or lower than the saturation concentration at room temperature in view of the handleability of the solution at room temperature.

The amount and rate of addition of the aqueous alkali halide solution are adjusted so that the pBr value of the solution during addition is 1.0 to 2.5.
It is determined by adjusting to keep.

As the addition rate of the AgNO ₃ aqueous solution is increased, the flattening rate becomes higher. However, since the stirring cannot catch up, practically, the addition rate per liter of aqueous solution is 1 g / min to 30 g. / Min (as the amount of AgNO ₃ ) is appropriate.

In this case, it is preferable that one or both of the aqueous AgNO ₃ solution and the aqueous alkali halide solution contain gelatin.

This can prevent the aggregation of AgX particles even when the gelatin concentration in the reaction vessel is lower.
Further, it is possible to prevent generation of unintended particles having non-parallel twin planes.

The present invention is also advantageous in that an aqueous gelatin solution having a high flattening rate and a lower concentration region can be used, and the gelatin aqueous solution is not gelled up to about 5 ° C. . Undesirable phenomena, such as aggregation of AgX particles and formation of particles having non-parallel twin planes, are caused particularly at the outlets of the aqueous AgNO ₃ solution and the aqueous alkali halide solution to be added, i. This is considered to be due to the fact that the generated AgX concentration is increased. Therefore, it is considered that these can be removed by adding gelatin to the aqueous solution.

The gelatin used here is preferably the same as that described above. In particular, A
As the gelatin used for the gNO ₃ aqueous solution, alkali-treated gelatin (for example, deionized alkali-treated gelatin or low-molecular-weight alkali-treated gelatin) is preferable. The gelatin concentration is generally 0.05 to 2.0% by weight, preferably about 0.05 to 1.6% by weight.

As the concentration of alkali halide, eg, KBr, in the aqueous gelatin solution in the reaction vessel is increased, the particle shape is changed to a) octahedral regular particles → b) particles having a single twin plane → c) parallel particles. Tabular grains having twin planes (target) → d) Changes like grains having non-parallel twin planes, but not only the target of c) but also b) and d) as described above I do. In particular, d) is difficult to remove even in the subsequent aging step. As described above, since the gelatin concentration near the addition outlet does not become uneven, b), c),
It becomes easier to make d).

By incorporating gelatin in one or both of the solutions, the conventional method can be used without producing coalesced particles up to a concentration of 0.4% by weight of gelatin in the reaction vessel. Up to 0.05% by weight can be used.

When gelatin is included in only one solution, it is more effective to include it in an aqueous AgNO ₃ solution than to include it in an aqueous KBr solution.

Further, an aqueous AgNO ₃ solution to be added and KBr
When the gelatin concentration of the aqueous solution is in the range of 0.05 to 2.0% by weight, particularly in the range of 0.05 to 1.6% by weight, it can be used at room temperature, does not require heating, and does not require any special additional equipment.

Nucleation is at about room temperature (20 ° C.) ± 15 ° C.
Temperature, the reaction vessel temperature and the
The temperatures of the aqueous gNO ₃ solution and the aqueous alkali halide solution become substantially equal, and the temperature of the solution near the addition outlet of these two aqueous solutions is kept very uniform. This also facilitates the above-mentioned b), c) and d).

The optimal addition rate of AgNO ₃ per liter of gelatin aqueous solution is 1 to 30 g / min · liter. This is because the nucleation probability of tabular grains increases as the addition rate increases, but if it is too high, it becomes difficult to make the above-mentioned b), c) and d) separately.

[0055] As the composition of the alkali halide solution on the side of the addition, Br ^- enough flat rate content comprising the higher of the increases ^- I against. I ^- is the AgBrI to be generated
Cannot be added beyond the solid solution limit of Therefore, its I ^- content is 31.2 + 0.165 (t-25) mol%
(T; temperature) or less.

The flattening rate can also be increased by lowering the stirring efficiency by lowering the rotation speed of the stirring blades during nucleation.

The nucleated tabular grains are subsequently Ostwald-ripened.

In particular, in the case of the present invention, since the nucleation is carried out at a low temperature, the grains formed are fine particles, and this ripening process is usually performed more slowly than the conventional emulsion which has carried out nucleation at 40 ° C. or higher. It has the advantage of being performed efficiently.

The ripening is performed at the silver potential (relative to the standard calomel electrode).
It is carried out at 40 to +60 mV, preferably at -30 to +60 mV. The temperature in this case is desirably 45 to 80 ° C.

The reason why the silver potential is set in such a range is that tabular grains having a high growth rate appear, and tabular grains having a large grain size are mixed to broaden the grain size distribution of the tabular grains. This is for preventing the existence ratio of the particles having non-parallel twin planes from increasing. The silver potential during nucleation is-
100 to -40 mV.
In order to increase the temperature to +60 mV, the temperature at the time of ripening is higher than that at the time of nucleation by 30 ° C. or more. For example, even if the temperature is -45 mV at 25 ° C during nucleation, if the temperature is raised to 60 ° C, it becomes -20 mV.

If the above ripening potential is not achieved only by this temperature rise, the following method is preferably used. 1) At the time of nucleation, an aqueous solution of AgNO ₃ and an aqueous solution of an alkali halide are added to the reaction vessel by a double jet in the presence of an alkali halide, for example, KBr. After the double jet addition is completed, or the aging temperature is further increased. After that, the silver potential of the solution in the reaction vessel is raised by continuing to add only the AgNO ₃ aqueous solution. 2) After the nucleation, the emulsion is washed once with water, and then an optimum amount of an alkali halide, for example, KBr is added. 3) After nucleation, the halogen ion concentration is reduced by an ultrafiltration method (see Japanese Patent Publication No. 59-43727).

As described above, preferably, gelatin is added after or before adjusting the concentration of an alkali halide, for example, KBr, to adjust the gelatin concentration to 1.5 to 10% by weight, and then the temperature is increased to carry out ripening. During this ripening period, ripening may be performed while adding the aqueous AgNO ₃ solution and the aqueous KBr solution by double jet at a rate of 0 to 20%, preferably 1 to 15% of the critical growth rate of the tabular grains. This is to prevent the edge trough portion of the tabular grains from becoming round at the time of ripening, thereby preventing the selective growth property from being lowered.

In the neutralization step 1), the tabular grains are selectively grown, discrimination is added to the stability of the tabular grains and the non-tabular grains. It has the meaning of making elimination easier.

After aging as described above, the particles are grown. The grain growth is at a silver potential of -40 to +30 mV and a temperature of 45 to 45 mV.
At 80 ° C., the addition is effected substantially by the controlled double jet addition of an aqueous solution of AgNO ₃ and an aqueous solution of an alkali halide, but at a rate at which no new nuclei are formed and no longer than Ostwald ripening of the tabular grains. Rate, the addition rate of which increases with particle growth. Substantially refers to a period that is equal to or longer than half of the crystal growth period. Specifically, the addition rate is set to a growth rate of about 20 to 100%, preferably about 30 to 100% of the critical growth rate of crystal grains.

The range of the silver potential in the above range is -40 m
If it is less than V, the size distribution of the particle size is unfavorably wide, and if it exceeds +30 mV, on the contrary, the aspect ratio becomes too small and the effect of the present invention cannot be obtained.

A method for increasing the addition rate of silver ions and halogen ions is described in JP-B-48-3.
As described in JP-A-6890 and JP-A-52-16364, the addition rate (flow rate) of a silver salt aqueous solution and a halogen salt aqueous solution having a constant concentration may be increased, or the concentrations of the silver salt aqueous solution and the halogen salt aqueous solution may be increased. You may. Alternatively, an ultrafine grain emulsion having a size of 0.10 μm or less may be prepared in advance, and the addition speed of the ultrafine grain emulsion may be increased. Further, these may be superimposed. The addition rates of silver ions and halogen ions may be increased intermittently or continuously.

In this case, how to increase the addition rates of silver ions and halogen ions depends on the concentration of the coexisting colloid, the solubility of silver halide crystal grains, the degree of stirring in the reaction vessel, The size and concentration of the crystals present, the hydrogen ion concentration of the aqueous solution in the reaction vessel (p
H), the silver ion concentration (pAg), etc., and the final size and distribution of the target crystal grains, which can be easily determined by a routine experiment.

That is, the upper limit of the addition rate of the silver ion and the halogen ion may be slightly smaller than the addition rate at which new crystal nuclei are generated. Regarding the addition rate of, a crystal may be actually formed, sampled from a reaction vessel, and observed under a microscope to confirm the presence or absence of generation of a new crystal nucleus.

These are described in JP-A-55-14232.
No. 9 can be referred to.

The relationship between the silver potential and the aspect ratio in the entire growth period is described below. However, this relationship is a standard for particles having a projected particle size of 1.0 μm. Larger sizes result in higher aspect ratios.

During growth, AgX is deposited on the nucleus.
Is preferably from 0 mol% to the solid solution limit concentration.

In the case of a negative light-sensitive material, the iodine content of the outermost shell is preferably 5 mol% or less from the viewpoint of developability.

The pH of the solution during the growth period, the silver halide solvent to be used, the stirring method, and the type of binder can be referred to those described in JP-A-55-142329, and others are described later.

Further, after growing the particles, Ostwald ripening may be performed, if necessary. As a result, fine (0.1 μm or less) silver halide grains can be eliminated. The ripening is preferably performed under the same conditions as the ripening after the nucleation. That is, the silver potential (relative to the standard calomel electrode) -40 to +60 m
V, preferably -30 to +60 mV. The temperature in this case is 45-80 ° C.

Usually, in the emulsion production method, the temperature at which silver halide grains are formed is 40 to 80 ° C.
8-113926, 58-113927, 58
No. 113928). This is because the production efficiency is better when the particles are grown at a high temperature for a short time to produce particles of a desired size, and the gelatin solution is prevented from being gelatinized, rather than performing the crystal growth at a low temperature for a long time. However, in the method of the present invention, nucleation, ripening, and growth are performed independently, so that the temperature can be set separately. That is, since the crystal growth is carried out at 45 to 80 ° C., there is no problem in terms of productivity, and conditions most favorable for nucleation of tabular grains can be selected.

The tabular grains of the present invention can be used as an emulsion by themselves. As described later, negative tabular grains having various aspect ratios and a controlled halogen composition of shells are used as seed crystals as described later. (Diameter: 0.6 to 4 μm) can also be prepared. The emulsion obtained by the present invention can be used as a core / shell type autopositive emulsion using the grains as a core. The method of shell attachment can be performed under the same conditions as in the crystal growth of the present invention, but is described in U.S. Pat. Nos. 3,761,276 and 4,26.
Nos. 9,927 and 3,367,778 can be referred to.

The silver halide in the present invention includes, for example, silver bromide, silver iodobromide and silver chloride having a content of 30 mol%.
The following silver chlorobromide, silver chloroiodobromide and the like.

The emulsion prepared by the method of the present invention comprises
Preferably, the silver iodide is mainly composed of silver iodobromide grains. The distribution of silver iodide in the grains may be uniform, high in internal density, or high in surface density.

By using the preparation method of the present invention, the grain size distribution of tabular silver halide grains can be narrowed.

The preparation method of the present invention is used for a silver halide emulsion mainly composed of silver iodobromide grains having a high aspect ratio.
It is preferably used for those having a size of 20 to 20, particularly preferably 4 to 16.

Here, the aspect ratio is the ratio of the “diameter” to the grain thickness, and the “diameter” is the diameter of a circle having an area equal to the projected area of the emulsion grains when the emulsion grains are observed with a microscope or an electron microscope. Shall be referred to.

The average aspect ratio is the average of the aspect ratios of individual tabular grains. When actually determining the average aspect ratio, the average aspect ratio of all tabular grains having a diameter of 0.15 μm or more is determined. 0.15μm diameter
The reason for limiting to the above tabular grains is that only a small amount of an emulsion composed of fine grains having a diameter of 0.15 μm or less is mixed into the emulsion composed of tabular grains, and the photographic characteristics thereof are not largely changed. Is greatly changed.

The method of the present invention is preferably used for emulsions in which silver halide grains mainly composed of silver iodobromide having a high aspect ratio are present in a proportion of 70% to 100% of the total projected area. Further, it is more preferably used for an emulsion present at a ratio of 75% or more.

In the ripening process of the present invention, a silver halide solvent may be used to accelerate ripening. During the crystal growth period after the ripening, a silver halide solvent may be used to promote the crystal growth.

Examples of frequently used silver halide solvents include thiocyanates, ammonia, thioethers and thioureas.

For example, thiocyanates (US Pat. No. 2,2
No. 22,264, No. 2,448,534, No. 3,
320,069), ammonia, thioether compounds (for example, U.S. Pat. Nos. 3,271,157, 3,574,628, 3,704,130, 4,297,439); No. 4,276,347) and thione compounds (for example, JP-A-53-144319).
Nos. 53-82408 and 55-77737), amine compounds (for example, JP-A-54-100717).
Number etc.) can be used.

In the course of silver halide grain formation or physical ripening, cadmium salt, zinc salt, lead salt, thallium salt, iridium salt or its complex salt, rhodium salt or its complex salt, iron salt or iron complex salt, etc. Good.

As the dispersion medium (binder or protective colloid) of the photographic emulsion of the present invention, the above-mentioned gelatin is advantageously used, but other hydrophilic colloids can also be used.

For example, gelatin derivatives, graft polymers of gelatin and other polymers, proteins such as albumin and casein; cellulose derivatives such as hydroxyethylcellulose, carboxymethylcellulose and cellulose sulfates; sugars such as sodium alginate and starch derivatives. Derivatives: polyvinyl alcohol, polyvinyl alcohol partial acetal, poly-N-vinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide,
Various kinds of synthetic hydrophilic high molecular substances such as a single or copolymer such as polyvinylimidazole and polyvinylpyrazole can be used.

As the gelatin, in addition to the above-mentioned lime-treated gelatin, acid-treated gelatin and Britain Society
Of the Scientific Photography of Japan (Bull. Soc. Sci. Phot. Japan.) No. 16,
Oxygen-treated gelatin as described on page 30 (1966) may be used, and hydrolysates or enzymatic degradation products of gelatin can also be used. As the gelatin derivative, various compounds such as acid halides, acid anhydrides, isocyanates, bromoacetic acid, alkane sultones, vinylsulfonamides, maleimide compounds, polyalkylene oxides, and epoxy compounds are added to gelatin. What is obtained by reacting is used.

The dispersion medium used in the present invention is specifically described in Research Disclosure, Vol. 176, No. 17
643 (December 1978), section IX.

The photographic emulsion used in the present invention is known as an antifoggant or stabilizer for the purpose of preventing fogging during the production process, storage or photographic processing of a photographic material, or stabilizing photographic performance. And various other compounds.

The photographic emulsion layer of the photographic light-sensitive material prepared according to the present invention may contain, for example, polyalkylene oxide or its derivatives such as ethers, esters, amines, thioether compounds, etc. for the purpose of increasing sensitivity, increasing contrast, or accelerating development. It may contain thiomorpholines, quaternary ammonium salt compounds, urethane derivatives, urea derivatives, imidazole derivatives, 3-pyrazolidones, and the like.

The sensitizing dyes used in the present invention include 176, Research Disclosure, Item 1764.
3 IV, P23 (December, 1978).

The sensitizing dye can be used in any step of the production process of the photographic emulsion and can be used at any stage after the production and immediately before coating. Examples of the former include a silver halide grain forming step,
Physical ripening step, chemical ripening step and the like.

The silver halide emulsion of the present invention can be provided, if necessary, with one or more (eg, two or three) layers on a support together with other emulsions. 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 silver halide emulsion of the present invention can be used as a black-and-white silver halide photographic light-sensitive material (for example, X-ray light-sensitive material, lith-type light-sensitive material, negative film for black-and-white photography) or a color photographic light-sensitive material (for example, color negative film, Color reversal film, color paper, etc.). Further, a photosensitive material for diffusion transfer (for example, a color diffusion transfer element,
Silver salt diffusion transfer element), photothermographic material (black and white, color)
It can also be used for example.

In addition, the emulsion water washing method, chemical sensitization method, antifoggant used, dispersion medium, stabilizer, curing agent, dimensional stability improving agent, antistatic agent, coating aid, dye,
Research on color couplers, adhesion prevention, and photographic property improvement (eg, development acceleration, high contrast, sensitization)
Disclosure Magazine, Volume 176, December 1978, December Issue (Item 17643), Japanese Patent Laid-Open No. 58-113926
Nos. 58-113927, 58-11328 and 59-90842 can be referred to.

As described above, the features of the present invention can be summarized as follows.

In the present invention, a high flattening rate can be obtained in a solution having a lower Br ^- concentration by setting the nucleation period to a low temperature and a low gelatin concentration. This is different from the conventional method of increasing the flattening rate by increasing the Br ^- concentration of the solution during nucleation.

In order to increase the tabular ratio, a. Other methods include: a. Lowering the gelatin concentration of the aqueous gelatin solution;
b. using modified gelatin such as phthalated gelatin, c. addition of I ⁻ to the Br ⁻ solution to be added, d.
Increasing the rate of addition of ₃ , e. Increasing the pH of the solution, and f. Deteriorating the stirring conditions were effective, and all of these methods were found to be additive to each other.

In the present invention, the above-mentioned b), c), d)
In order to make the separation of B more accurately, B during nucleation
It has been found that it is preferable to keep the r ^- concentration, gelatin concentration and the conditions such as b. to f. above which affect the flattening ratio constant. Here, these condition factors will be referred to as supersaturation factors for metastable nuclei of growth on AgX particles.

In the present invention, when the temperature is low and the Br ^— concentration is low, the formed tabular grains do not grow rapidly in the main surface direction, so that no large tabular grains are mixed and the tabular grains have a narrow size distribution. Particles are obtained. Generally, high temperature, high Br
^{In a} -concentrated solution, tabular grains grow very quickly in the direction of their main surface, unlike large tabular grains.

In the present invention, when nucleation is carried out in a low-temperature, low-Br ^- concentration solution, the generated particles are fine particles, and the next ripening process following nucleation is effectively performed. That is, since the aging process is completed at a lower temperature and in a shorter time, the size of the seed crystal of the tabular grains can be suppressed to be small, and the spread of the size distribution can be suppressed.

The embodiments of the present invention are as follows. (1) In a method for producing a silver halide emulsion containing tabular silver halide grains having parallel twin planes by subjecting the silver halide grains to nucleation, Ostwald ripening and grain growth, a temperature of 5 to 30 ° C. A method for producing a silver halide emulsion, characterized in that nucleation is carried out under the following conditions.

(2) In (1), nucleation was pBr1.
A method for producing a silver halide emulsion, which is a double jet mixing of an aqueous solution of AgNO ₃ and an aqueous solution of an alkali halide in an aqueous gelatin solution of 0 to 2.5.

(3) A method for producing a silver halide emulsion according to (2), wherein the condition of the supersaturation factor (described in the text) during the nucleation period is kept constant.

(4) In (1) to (3), a silver halide emulsion wherein the ripening process following nucleation is at a temperature of 45 to 80 ° C., and the silver potential of the solution (with respect to the calomel standard electrode) is -40 to +60 mV. Manufacturing method.

(5) In the aging process in (4),
A method for producing a silver halide emulsion using the silver halide solvent described in the text.

(6) In (1) to (5), a period of at least half of the growth process following the ripening process is performed at a temperature of 45 to 80.
C., a silver potential (standard electrode against calomel) of -40 to +30 mV, and a method for producing a silver halide emulsion having a critical growth rate of 30 to 100%.

(7) A method for producing a silver halide emulsion which is ripened under the ripening conditions described in (5) and (6) after crystal growth.

[0112]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention. However, the present invention is not limited to these examples. Example 1 In a reaction vessel having a volume of 4 liters, an aqueous solution of gelatin (1000 ml of water, 7 g of deionized alkali-treated gelatin, 4 g of KBr; pH of 1.2 ml of 1 N KOH solution)
6.0, pBr 1.47) was added, and the solution temperature was adjusted to 2
While maintaining the temperature at 5 ° C., 160 ml of an AgNO ₃ aqueous solution (AgN ₃
O ₃ containing 32.6 g) and an aqueous KBr solution 160 ml (K
(Including 24.08 g of Br) simultaneously over 4 minutes (flow rate;
40 ml / min) and stirred for 2 minutes.
The emulsion was precipitated at pH 4.0 by adding N nitric acid solution and washed with water. The yield was 400 ml, 200 ml of which was used as a seed crystal emulsion, and this was added to an aqueous gelatin solution (1150 ml of water, K
After adding 2 g of Br and 25 g of deionized alkali-treated gelatin) to adjust the pH to 6.4, the temperature was raised to 60 ° C.
In this case, the silver potential during the nucleation phase before raising the temperature to 60 ° C. was −45 mV. In addition, pBr in the nucleation phase is 1.
It is about 47.

Aged at 60 ° C. for 18 minutes (silver potential −20)
mV) and then 250 ml of an aqueous AgNO ₃ solution (AgNO ₃ 26
g of KBr aqueous solution and 250 ml of KBr aqueous solution (KBr18.9)
4 g) were added simultaneously over 25 minutes. During this time,
The silver potential of the solution showed a stable silver potential of -20 mV. 5
After leaving the mixture to stand for 250 minutes, the AgNO ₃ aqueous solution was again dissolved in 250 ml (A
gNO ₃ 39g) and KBr aqueous solution 250ml (K
(Including 28.0 g of Br) simultaneously over 25 minutes (flow rate 1
0 ml / min). The silver potential at this stage is -20
mV. After stirring for 5 minutes after the end of the addition, the temperature was raised to 75
℃, aging for 30 minutes, then lower the temperature to 30 ℃,
The emulsion was washed with water and dispersed. The solution addition in this example was all in the liquid, and the solution addition system used was a pulse motor driven syringe-shaped addition system.

A replica image of the obtained emulsion grains was observed under a transmission electron microscope (TEM) at a magnification of 2000 times, and all tabular grains 600 having a diameter of 0.15 μm or more were observed.
The average particle size and average thickness of each piece were examined, and the aspect ratio (average particle size / average thickness) was determined.

Further, the diameter of the grain relative to the total projected area of the grain is 0.1 mm.
The proportion occupied by the projected area of tabular grains of 15 μm or more was examined. The coefficient of variation of the diameter of tabular grains having a diameter of 0.15 μm or more was determined.

The values shown in the following examples are values obtained in the same manner. Average particle size 0.42 μm Average thickness 0.076 μm Average aspect ratio 5.5 Ratio occupied by tabular grains 93.6% Coefficient of variation of projected particle size 22% A TEM photograph in this case is shown in FIG. FIG. 2 shows a TEM photograph of a replica image of the emulsion grains before the temperature was raised to 75 ° C. in the above.

Comparative Example 1 (Conventional Method) The amount of deionized alkali-treated gelatin in an aqueous gelatin solution to be put in a reaction vessel was 12.5 g, the temperature at the time of nucleation was 40 ° C., and after washing with water and before aging. Deionized alkali-treated gelatin in aqueous gelatin solution
Emulsions were prepared under the same conditions except that the weight was 2.25 g. FIG. 3 shows a TEM photograph in this case. 2 and 3
It can be seen from the comparison that the amounts of silver added are all the same, so that nucleation in the low-temperature, low-concentration gelatin region of the present invention can provide a higher tabular grain ratio and a smaller grain size. .

Example 2 In a reaction vessel having a volume of 4 liters, an aqueous gelatin solution (1000 ml of water, 7 g of deionized alkali-treated gelatin, 3 g of KBr; 1.2 ml of 1 NKOH solution, pH 6.0).
0, pBr1.6), and while maintaining the solution temperature at 25 ° C., an aqueous AgNO ₃ solution (35.4 g of AgNO ₃ ,
Water (174 ml) and KBr aqueous solution (KBr 23.78 g,
(160 ml of water) at the same time at a flow rate of 40 ml / min for 4 minutes. At this point, only the remaining AgNO ₃ aqueous solution was continuously added over 21 seconds, and 1.96 g of excess 3.96 g of KBr was added. And the excess was reduced to 2 g. In this case, the washing performed in the first embodiment can be omitted. Next, a half amount of this emulsion was used as a seed crystal, and an aqueous gelatin solution (683 ml of water, 1 g of KBr, 20 g of deionized alkali-treated gelatin) was added thereto, followed by stirring for 10 minutes.

The pBr in the nucleation stage is about 1.6. Thereafter, processing is performed in the same manner as in Example 1, and TEM is performed similarly.
Was observed. Average particle diameter 0.41 μm Average thickness 0.077 μm Average aspect ratio 5.3 Ratio of tabular grains 95% Variation coefficient of tabular grains 21.3%

FIG. 4 shows a TEM photograph in this case. It can be seen that the result is almost the same as that of the first embodiment. in this case,
Since the amount of the seed crystal was reduced to half, 1 g of KBr was added.
When the seed crystal is used as it is, the addition of KBr is unnecessary.

Example 3 In Example 1, after ripening, treatment was carried out in the same manner as in Example 1, except that the addition of the second aqueous AgNO ₃ solution and the aqueous KBr solution was omitted. Average particle size 0.32 μm Average thickness 0.076 μm Average aspect ratio 4.2 Ratio occupied by tabular grains 88% Ratio occupied by grains whose projected particle size is 0.6 μm or less 99.8% Coefficient of variation 19% It can be seen that tabular grains are obtained.

Example 4 In Example 1, the gelatin at the time of nucleation was 12.5 g of deionized alkali-treated gelatin, and the amount of KBr previously added to the reaction vessel was 10 g (pBr 1.08).
The addition of an aqueous solution of NO ₃ and an aqueous solution of KBr were added in 16 minutes. After raising the temperature to 60 ° C., 2 m of 25% aqueous ammonia was added.
1 and 2 ml of a 50% NH ₄ NO ₃ aqueous solution, and after 5 minutes, a crystal growth was started and a silver potential at the time of crystal growth was set to −10 mV.
An emulsion was prepared in the same manner as described above.

The pBr in the nucleation stage is about 1.08. A replica image of this emulsion was prepared using a TEM (magnification: 5000).
Times). Average particle size 0.81 μm Average thickness 0.188 μm Average aspect ratio 4.3 Ratio occupied by tabular grains 75% Variation coefficient 8.1% A TEM photograph in this case is shown in FIG.

In the above, mixing of non-parallel twin grains is observed due to the relatively high Br ^- concentration at the time of nucleation, but it is still improved as compared with the conventional method.

Example 5 In Example 1, the amount of the deionized alkali-treated gelatin to be added into the reaction vessel was 4 g, the amount of KBr was 0.8 g (pBr2.17), and the amount of AgNO ₃ added at the time of nucleation was set. Deionized alkali-treated gelatin was added to the aqueous solution and the aqueous KBr solution, and this gelatin was 0.4% by weight.
The amount of gelatin added to the aqueous gelatin solution added to the aqueous gelatin solution after washing with water and before aging was 2%.
The same treatment was performed except that the amount was 1.7 g.

The pBr at the time of nucleation is about 2.17. Then, it observed similarly with TEM. Average particle size 0.43 μm Average thickness 0.078 μm Average aspect ratio 5.5 Ratio of tabular grains 96% Variation coefficient 22%

Example 6 In a reaction vessel having a capacity of 4 liters, an aqueous solution of gelatin (1000 ml of water, phthalated gelatin (phthalation rate 9
0%) 12.5 g, KBr 5 g, pH 6.0 with 1 N KOH.
0, pBr 1.35) was added, and the solution temperature was set to 25 ° C.
While maintaining the pressure at 160 ° C., containing 160 ml of AgNO ₃ aqueous solution (32.6 g) and 160 ml of KBr aqueous solution (24.45 g of KBr).
) Was added simultaneously over 4 minutes (flow rate 40 ml / min), followed by stirring for 2 minutes, followed by addition of a 1N nitric acid solution.
The emulsion was sedimented at pH 3.8 and washed with water. 400m yield
1 and 200 ml of the emulsion was used as a seed crystal emulsion. In addition, pBr at the time of nucleation is about 1.35.

A replica image of the obtained emulsion grains was taken at a magnification of 2,
Observation with a TEM at a magnification of 000 was performed, and the average particle diameter and average thickness of 600 tabular grains having a diameter of 0.15 μm or more were examined to determine the average aspect ratio.

The ratio of tabular grains to the total projected area of the grains and the coefficient of variation were also examined. Average particle size 0.48 μm Average thickness 0.08 μm Average aspect ratio 6.0 Ratio of tabular grains 94% Variation coefficient 19.3%

Example 7 An aqueous gelatin solution (1000 ml of water, 2.0 g of deionized alkali-treated gelatin, 1.8 g of KBr, adjusted to pH 6.0 with 1N KOH, pBr 1.82) was placed in a reaction vessel having a capacity of 4 liters. While maintaining the solution temperature at 30 ° C., 160 ml of an AgNO ₃ aqueous solution (AgNO ₃ 3
2.6 g and deionized alkali-treated gelatin 0.32 g
) And 160 ml of an aqueous KBr solution (23.2 g of KBr)
And 0.32 g of deionized alkali-treated gelatin)
Was added simultaneously over 4 minutes (flow rate 40 ml / min), followed by stirring for 2 minutes.
0 ml, 25 g of deionized alkali-treated gelatin) was added to adjust the pH to 6.4, and then ripened and grown as in Example 1. The pBr during nucleation is about 1.82.

A replica image of the obtained emulsion grains was taken at a magnification of 2,
Observation with a TEM at a magnification of 000 was performed, and the average particle diameter and average thickness of 600 tabular grains having a diameter of 0.15 μm or more were examined to determine the average aspect ratio.

Further, the diameter of the grain relative to the total projected area of the grain is 0.1 mm.
The proportion occupied by tabular grains of 15 μm or more and the coefficient of variation were examined. Average particle size 0.43 μm Average thickness 0.074 μm Average aspect ratio 5.8 Ratio of tabular grains 92% Variation coefficient 20.0%

Example 8 An aqueous gelatin solution (1000 ml of water, deionized alkali-treated gelatin 1) was placed in a reaction vessel having a capacity of 4 liters.
2.5 g, 9 g of KBr, adjusted to pH 6.0 with 1 N KOH, pBr 1.12), 192 ml of an aqueous AgNO ₃ solution (AgNO ₃ 16.
3 g) and 130 ml of KBr aqueous solution (KBr11.
After stirring for 2 minutes, a precipitant and a 1N nitric acid solution were added to precipitate the emulsion at pH 4.0 and washed with water.

The yield was 400 ml, of which 100 ml
Is used as a seed crystal emulsion, and an aqueous gelatin solution (water 1000 m
1, 20 g of deionized alkali-treated gelatin, 1 N K
OH adjusted to pH 6.4) to bring the temperature to 60 ° C.
2 ml of Br (10% by weight) was added, and after 5 minutes, the silver potential of the solution was set to −25 mV, and then 2 ml of an aqueous solution of NH ₄ NO ₃ (50% by weight) and aqueous solution of NH ₃ (25% by weight) 2 ml
After 5 minutes, while maintaining the silver potential of the solution at −25 mV, 200 ml of an AgNO ₃ aqueous solution (10 g of AgNO ₃ was added).
g) and 175 ml of KBr aqueous solution (including 7 g of KBr)
Was added over 25 minutes to form an emulsion. The pBr during nucleation is about 1.12.

A replica image of this emulsion was prepared using a TEM (magnification: 30).
00). Average particle size 0.87 μm Average thickness 0.068 μm Average aspect ratio 13 Ratio occupied by tabular grains 90% Variation coefficient 16.8% A TEM photograph image in this case is shown in FIG.

Example 9 An aqueous gelatin solution (1000 ml of water, deionized alkali-treated gelatin 7) was placed in a reaction vessel having a capacity of 4 liters.
g, KBr 4.5 g, 1 N KOH solution 1.2 ml, p
Br1.42) and keeping the solution temperature at 30 ° C.
25 ml of AgNO ₃ aqueous solution (including 8.0 g of AgNO ₃ ) and 25 ml of KBr aqueous solution (including 5.8 g of KBr)
Are added simultaneously over 1 minute (flow rate 25 ml / min),
After stirring for 350 minutes, 350 ml of the mixture was used as a seed crystal, and a gelatin aqueous solution (650 ml of water, 20 g of deionized alkali-treated gelatin, 3.4 ml of a 1N KOH aqueous solution,
KBr (0.5 g) is added and the temperature is raised to 75 ° C. After heating, aging for 30 minutes (silver potential -23 mV), AgNO
₃ aqueous solution (containing 40 g of AgNO ₃ in 400 ml) and an aqueous KBr solution (containing 33 g of KBr in 400 ml) for 10 minutes at a silver potential of +10 mV and 10 ml / min. D.
J. (Controlled double jet). After the addition was completed, the mixture was stirred for 5 minutes, and further charged at a silver potential of +10 mV for 1
C. at 5 ml / min for 20 minutes. D. After adding J and stirring for 3 minutes, the emulsion was washed with water and dispersed. A replica image of the obtained emulsion particles was observed with a TEM (2000-fold magnification).

Average particle size 0.56 μm Average thickness 0.094 μm Average aspect ratio 6.0 Ratio occupied by tabular grains 90% Variation coefficient 16.0% A TEM photograph image in this case is shown in FIG.

Example 10 350 ml of the same seed crystal as in Example 9 was used, and a gelatin aqueous solution (650 ml of water, 20 g of deionized alkali-treated gelatin, 3.4 ml of 1N KOH aqueous solution, KBr1.
2 g) was added and the temperature was raised to 75 ° C. After heating, AgN
40 ml of O ₃ aqueous solution (containing ₃ g of AgNO ₃ ) and KBr
40 ml of an aqueous solution (containing 2.3 g of KBr) was added for 40 minutes,
Aging (silver potential -33 mV) while adding at 1 ml / min,
Next, the temperature was lowered to 60 ° C., and an AgNO ₃ aqueous solution (400 m
1 containing 50 g of AgNO ₃ ) and an aqueous KBr solution (40
0 ml containing 40 g), silver potential -10 mV, 10 ml
/ Min for 10 minutes, C.I. D. J was added. After completion of addition, 5
After stirring for 30 minutes, C.I. D. J. After addition and stirring for 3 minutes, the emulsion was washed with water and dispersed. A replica image of the obtained emulsion particles was observed with a TEM (2000-fold magnification).

Average particle size 0.84 μm Average thickness 0.093 μm Average aspect ratio 9.04 Ratio occupied by tabular grains 98% Coefficient of variation 19.0%

Example 11 In a reaction vessel having a capacity of 4 liters, an aqueous gelatin solution (1000 ml of water, 8 g of deionized alkali-treated gelatin, 5 g of KBr, pH 6.0) was added, and the solution temperature was adjusted to (25 ° C., 30 ° C., 38 ° C.). ° C., 40 ° C., while maintaining the 50 ° C.), the AgNO ₃ solution 100 ml (AgNO ₃ 32.
6 g) and 100 ml of KBr aqueous solution (KBr 23.8)
g) simultaneously over 4 minutes (flow rate 25 ml / min)
After adding and stirring for 2 minutes, 200 ml of the emulsion was taken out and used as a seed crystal. This seed crystal was added to an aqueous gelatin solution (containing 800 ml of water, 20 g of gelatin, 1.5 g of KBr, and 4.3 ml of 1N KOH) in a reaction vessel having a capacity of 4 liters, and after stirring for 2 minutes, the temperature was raised to 75 ° C.
After aging for 40 minutes, the temperature was lowered to 60 ° C., and AgNO ₃
While maintaining 200 ml of the aqueous solution (containing 25 g of AgNO ₃ ) and the aqueous KBr solution at −5 mV, the C.I. D.
J. Was added. After stirring for another 2 minutes, the emulsion was washed with water,
Dispersed. With respect to the obtained emulsion grains, the replica image was observed under a transmission electron microscope (TEM) at a magnification of 3000 times to examine the characteristics of the tabular grains. The results are shown in Table 1 below.

[0141]

[Table 1]

From the results shown in Table 1, it is found that those having a nucleation temperature of 30 ° C. or lower exhibit extremely good monodispersity for practical use.

[Brief description of the drawings]

FIG. 1 is a drawing substitute photograph showing a grain structure, which is a transmission electron micrograph of emulsion grains obtained by a method for producing a silver halide emulsion of the present invention.

FIG. 2 is a photograph substituted for a drawing showing a grain structure, and is a transmission electron micrograph of emulsion grains obtained by the method for producing a silver halide emulsion of the present invention.

FIG. 3 is a drawing substitute photograph showing a grain structure, which is a transmission electron micrograph of emulsion grains obtained by a conventional method for producing a silver halide emulsion.

FIG. 4 is a photograph substituted for a drawing showing a grain structure, and is a transmission electron micrograph of emulsion grains obtained by the method for producing a silver halide emulsion of the present invention.

FIG. 5 is a drawing substitute photograph showing a grain structure, and is a transmission electron micrograph of emulsion grains obtained by the method for producing a silver halide emulsion of the present invention.

FIG. 6 is a drawing substitute photograph showing a grain structure, and is a transmission electron micrograph of emulsion grains obtained by the method for producing a silver halide emulsion of the present invention.

FIG. 7 is a photograph substituted for a drawing showing a grain structure, and is a transmission electron micrograph of emulsion grains obtained by the method for producing a silver halide emulsion of the present invention.

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[Procedure amendment]

[Submission date] December 16, 1997

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

FIG. 2

FIG. 3

FIG. 4

FIG. 5

FIG. 6

FIG. 7

Claims (1)

[Claims] 1. A tabular silver halide grain having good monodispersity by passing through nucleation, Ostwald ripening and grain growth of the silver halide grain to give a total projected area of 70 to 100.
%, Wherein the nucleation is carried out at a temperature of 5 to 30 ° C. and a pBr of 1.0 to 2.5, and the nucleus has an I ⁻ content of [31.2 + 0.16
5 (t-25) mol% (t: nucleation temperature)] or less, and the Ostwald ripening is performed at 45 to 80 ° C. to eliminate non-tabular grains and increase the total projected area ratio of tabular grains. A method for producing a silver halide emulsion.