JPH04125628A - High-sensitivity silver halide photographic sensitive material - Google Patents

Abstract

PURPOSE:To improve sensitivity and pressure desensitization resistance by incorporating the silver halide particles obtd. by adding the silver halide particles obtd. by adding the silver halide particles which are smaller in solubility product than the grown particles previously prepd. in a reaction vessel to induce the growth of the particles and are finer in size than these particles into the above photosensitive material. CONSTITUTION:The silver halide particles which are the silver halide particles grown with spherical particles of <=2mol% silver iodide content subjected to Ostwald maturation at <=39 deg.C after nucleus formation as a seed emulsion and are obtd. by adding the silver halide particles (B) which are lower in the solubility product than the grown particles (A) previously prepd. in the reaction vessel to induce the growth of the particles (A) and are finer in size than these grown particles are incorporated into this photosensitive material. Namely, AgI, AgBr, AgCl, etc., of the fine sizes are added at the time of particle formation and thereafter, shells are formed and are grown to the planar particles, by which the particles of a high aspect ratio are grown. The silver halide photographic sensitive material having the high sensitivity and the excellent pressure desensitization resistance is obtd. in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a silver halide photographic material, and more specifically, to provide a silver halide photographic material with high sensitivity and excellent pressure desensitization resistance. be.

[Background of the invention]

In recent years, there has been an increasing demand for higher sensitivity and higher image quality of silver halide photographic materials, but on the other hand, such higher sensitivity deteriorates pressure desensitization resistance, which has become a problem.

In order to obtain a photosensitive material with such high sensitivity and excellent resistance to pressure desensitization, various changes were made to the shape, size distribution, and silver halide composition of the silver halide crystals in the light-sensitive silver halide emulsion. Control techniques have been proposed.

In order to achieve high sensitivity and improve granularity, particles with good monodispersity and a high aspect ratio are desirable.

JP-A-58-113934 discloses a color in which a tabular silver halide emulsion having a grain diameter/grain thickness ratio (hereinafter referred to as aspect ratio) of 8=1 or more is applied to a green-sensitive layer or a red-sensitive layer. Techniques for improving photographic materials are disclosed.

However, although high aspect ratio emulsions with an aspect ratio of 8:1 or higher are certainly excellent in light receiving efficiency, their latent image forming efficiency is not necessarily good, and they are not satisfactory as a method for improving sensitivity and graininess. It's not something I can do.

On the other hand, JP-A-61-14636, JP-A No. 61-112142
No. 63-163451 discloses a tabular twin emulsion that is monodisperse and has a core/shell structure, but it is not a sufficient improvement.

Further, Japanese Patent Application Laid-open Nos. 63-92942 and 51-39027 also disclose a production method that involves nucleation of tabular grains, Ostwald ripening or nucleation, Ostwald ripening, and grain growth. In the physical ripening of these patents, the Ostwald ripening is performed at 40° C. or higher, which increases the particle size of the seed crystals and improves monodispersity, but results in a low aspect ratio. Furthermore, if the Ostwald ripening time is shortened to reduce the particle size of the seed crystals in order to increase the aspect ratio, the monodispersity will be adversely affected.

Moreover, as processing speeds have increased in recent years, the influence of pressure caused by the handling of photosensitive materials, such as conveyance by rollers in automatic processors, has become greater, resulting in problems such as pressure desensitization.

As described above, silver halogenide photographic materials with high sensitivity, excellent graininess, and excellent resistance to pressure desensitization have not yet been obtained (1).

[Purpose of the invention]

In order to solve the above-mentioned problems, an object of the present invention is to provide a silver halogenide photographic material which is highly sensitive and has excellent pressure desensitization resistance.

[Structure of the invention]

The above-mentioned object of the present invention is to form silver halogenide grains in which 50% or more of the projected area has a grain diameter/grain thickness ratio of 2 or more.
In the production method of A), spherical grains with a silver iodide content of 2 mol% or less, which have been Ostwald-ripened at 3,900 mol or less after nucleation, are grown as a seed emulsion/) silver halide grains,
and a halogen obtained by adding silver halide grains (B) having a smaller solubility product and a finer size than the growth grains (A) prepared in advance into a reaction vessel in which the grains (A) are caused to grow. This is achieved by a silver halide photographic material containing silver halide grains.

The silver halide grains (B) include silver iodide, silver bromide,
Silver chloride is preferred.

The present invention will be explained in detail below.

Conventionally known spherical seed particles that have undergone nucleation and Ostwald ripening are subjected to Ostwald ripening at 40°C or higher as described above, which increases the particle size of the seed crystals and eliminates monodispersity, but the aspect ratio becomes low. Furthermore, if the Ostwald ripening time is shortened to reduce the particle size of the seed crystals in order to increase the aspect ratio, the monodispersity will be adversely affected. However, if Ostwald ripening is performed at 39° C. or lower, the monodispersity will be good and the particle size of the seed crystals will be small.

In addition, grains with a high silver iodide phase such as core/shell type are known to increase sensitivity, but when the high silver iodide phase is formed, monodispersity deteriorates and the aspect ratio decreases. Therefore, it is difficult to take full advantage of the above-mentioned advantages of reducing the particle size of the seed crystal.

Therefore, in the present invention, a fine-sized A
g1. By adding AgBr, AgCff, etc., and then forming shells and growing tabular grains, grains with a high aspect ratio could be grown without deterioration of monodispersity.

That is, unlike ordinary core/shell grains, the emulsion grains according to the present invention contain silver nitride fine grains in the form of a solid solution.

In addition, conventionally, pressure desensitization was degraded by using a core/shell type, but it was found that pressure desensitization was improved by performing particle growth using this method.

In the present invention, a monodisperse 7% silver halide emulsion means that the silver halide weight contained within a grain size range of ±20% around the average grain size 1 is 70% of the total silver halide weight. % or more, preferably 80% or more, more preferably 90% or more.

Here, the average particle size τ is the frequency n1 of particles with particle size d.
The particle size d when the product n, X d and 3 of d and 3 is the maximum. (3 significant figures, minimum 4 digits)
The particle size referred to here is the diameter when the projected image of the particle is converted into a circular image with the same area.

The particle size can be obtained, for example, by photographing the particles with an electron microscope at a magnification of 10,000 to 50,000 times, and actually measuring the particle diameter or projected area on the print. (The number of particles to be measured is assumed to be 1000 or more indiscriminately.

) Particularly preferred highly monodispersed emulsions of the present invention are those in which the breadth of the distribution defined by is 20% or less, more preferably 15% or less.

Here, the particle size measurement method shall follow the measurement method described above,
The average particle size is a simple average.

As a method for obtaining the silver halide emulsion of the present invention, a method in which a silver iodide-containing phase is precipitated on monodisperse seed crystals is preferably used. Particularly preferred is the method described in JP-A No. 61-6643, which includes a growth step for enlarging a monodisperse spherical bispecies emulsion.

That is, the silver halide emulsion of the present invention mainly has an even number of parallel twin planes, particularly preferably two twin planes.

The silver halide seed emulsion according to the present invention has spherical grains that have been Ostwald-ripened at 39°C or lower, preferably 30°C or lower, more preferably 20°C or lower, and have a silver iodide content of 2 mol% or lower, preferably 1 mol%. or less, preferably 0 mol%
It is.

For twinned grains with two or more parallel twin planes, when the particle is projected from a direction perpendicular to the twin plane, the distance between the equivalent circular diameter and the two particle surfaces parallel to the twin plane (thickness) ) (ratio of particle diameter/particle thickness) is 2 or more,
Preferably it is 3 or more, more preferably 5 or more.

Such tabular grains must account for 50% or more, preferably 70% or more, and more preferably 90% or more of the projected area of all silver halide grains.

The silver halide grains (B) which are finer and have a smaller solubility product than the grown grains added during grain formation are Agl, AgBr,
It is AgCQ, and its particle size is 0.5. It is preferably less than um, particularly preferably 0.01 to 0.1 μm.

In the method for producing a silver halide photographic emulsion by supplying a water-soluble silver salt solution and a water-soluble halide solution in the presence of a protective colloid to obtain the silver halide emulsion of the present invention, (a) silver iodide; The pBr of the mother liquor was set to 2.0 for a period of 172 or more from the initial stage of silver halide precipitate formation with a content of 0 to 5 mol%.
(b) Following the core particle generation step, the mother liquor contains 10-' to 2.0 moles of silver halide solvent per mole of silver halide, and (c) Next, a water-soluble silver salt solution, a water-soluble halide solution, and/or a water-soluble silver halide fine grain are added. The feature is that a growth step is provided to enlarge the seed particles.

Here, the mother liquor is a liquid (also containing a silver halide emulsion) used for preparing a silver halide emulsion to produce a finished photographic emulsion.

The silver halide grains formed in the core grain generation step are twin grains made of silver iodobromide containing 0 to 5 mol % of silver iodide.

Twin crystals refer to silver halide crystals that have one or more twin planes within one grain, but the classification of twin crystal morphology is based on a miscellaneous paper by Klein and Moyser.
she Korrespondenz volume 99 page 99,
It is described in detail in Volume 100, page 57. Two or more twin planes of a twin may or may not be parallel to each other.

In addition, the outer wall of the crystal consists of (111) planes, (100
) or both sides.

In the present invention, the twin core particles have a bromide ion concentration in the protective colloid aqueous solution of 0.01 to 5 mol/a, that is, pBr-2.
-0.7, preferably 0.03 to 5 mol/Q (p
It can be obtained by maintaining B r-1-5 to -〇, 7) and adding a water-soluble silver salt or a water-soluble silver salt and a water-soluble halide.

The nuclear particle generation step in the present invention refers not only to the period from the time when water-soluble silver salt is added to the protective colloid solution until substantially no new crystal nuclei are generated, but also the period after which the particles grow. It is defined as a step before the seed particle forming step.

Next, a description will be given of a seed grain formation step in which the core grains obtained in the core grain generation step are ripened in the presence of a silver halide solvent to obtain seed grains consisting of monodisperse spherical grains.

Ripening in the presence of a silver halide solvent (hereinafter simply referred to as ripening) is thought to generally lead to a broader grain size distribution, with the small grains dissolving and the larger grains growing when large and small grains coexist. This seems to be different from the Ostwald ripening that has been described. The conditions for ripening the seed grains from the core grains obtained in the core grain generation step include the core grain generation step in which twin core grains are produced using silver halide with a silver iodide content of 0 to 5 mol%. Substantially monodisperse spherical seed grains are obtained by ripening the emulsion mother liquor that has undergone the process in the presence of a silver halide solvent of lo-6 to 2.0 mol/silver mol. Substantially monodisperse is defined above as having a width of distribution less than 25%.

In addition, substantially spherical grains are defined as having a (111) plane or a (1
00) When a surface such as a surface is rounded to the extent that it cannot be clearly distinguished, and three-dimensional axes that are perpendicular to each other are set at one point near the center of gravity within the particle, the vertical, horizontal, and height of the plane image of the particle The maximum particle in the direction preferably refers to a particle in the range of 1.0 to 1.5.

Further, in the present invention, it is preferable that the spherical particles account for 70% or more, preferably 90% or more, and more preferably most of the total number of seed particles.

The silver halide solvent used in the seed grain forming step of the present invention includes (a) U.S. Pat. No. 3,271.157;
, 531.289, 3,574.628, JP-A-54-1019, JP-A-54-158917, and JP-A-58-30571;
(b) JP-A-53-82408, JP-A No. 55-29829
(C) AgX solvent having a thiocarbonyl group sandwiched between an oxygen or sulfur atom and a nitrogen atom, which is described in JP-A-53-144319; (d) Japanese Patent Publication No. 54-1007
Imidazole described in No. 17, (e) sulfite,
(f) Thiocyanates, (g) Ammonia, (h) Ethylenediamines substituted with hydroxyalkyl described in JP-A-57-196228, (i) JP-A-57-1962
Substituted mercaptotetrazoles described in No.-202531, (j) water-soluble bromide, (k) JP-A-58-54
Examples include benzimidazole derivatives described in No. 333.

Two or more of these solvents can be used in combination. Preferred solvents include thioethers, thiocyanates, thioureas, ammonia, and bromides, particularly preferably a combination of ammonia and bromide.

These solvents range from lo-6 to 1 mole of silver halide.
It is used in a range of 2 moles.

Also, the pH is 3 to 13, and the temperature is 30 to 70°C.
is preferable, particularly preferably pH 6-12 and temperature 35-12.
The temperature range is 50°C.

One example of a preferred embodiment of the present invention is pH 10,
8~11.2, ammonia 0.4~ at temperature 35~45℃
1.0 mol/Q and potassium bromide 0.03-0.5 mol/
By using Q in combination and ripening for 30 seconds to 10 minutes, an emulsion containing suitable seed particles was obtained.

A water-soluble silver salt may be added for the purpose of adjusting ripening during the seed particle forming step of the present invention.

The seed grain growth process that enlarges the silver halide seed grains is during precipitation of silver halide and during Ostwald ripening (1) pA
g, pH 1 is achieved by controlling the temperature, the concentration and silver halide composition of the silver halide solvent, and the rate of addition of the silver salt and halide solution.

In the present invention, fine particles (B) having a smaller solubility product than the grown particles are added to the obtained seed particles.

These fine particles exist within the particles as a completely solid phase.

Further, as conditions for enlarging these particles, as a method for preparing core/shell particles, for example, Japanese Patent Application Laid-open No. 51-39027
No. 55-142329, No. 58-113928, No. 54-48521 and No. 58-49938, a water-soluble silver salt solution and a water-soluble halide solution are added by a double jet method, An example of a method is to gradually change the addition rate according to the enlargement of particles within a range where new nucleation does not occur and Ostwald ripening does not occur.

As another condition for enlarging the seed grains, a method of enlarging the seed grains by adding silver halide fine grains, dissolving and recrystallizing can be used, as shown in the Proceedings of the 1988 Annual Conference of the Photographic Society of Japan, page 88, but the former The method is preferred.

When growing silver halide grains, it is preferable to add a silver nitrate aqueous solution and a halide aqueous solution by a double jet method. Youma can also supply silver iodide to the system. The addition rate is such that no new nuclei are generated and the size distribution does not widen due to Ostwald ripening, that is, 30% of the rate at which new nuclei are generated.
It is preferable to add in a range of 100% to 100%.

In producing the silver halide emulsion of the present invention, stirring conditions during production are extremely important. As the stirring device, the device shown in JP-A-62-160128, in which an additive liquid nozzle is installed in the liquid near the mother liquor inlet of the stirrer, is particularly preferably used. Also, at this time, the stirring rotation speed is 400 to 1
It is preferable to set it to 20 Orpm.

The silver halide emulsion used in the light-sensitive material of the present invention can be chemically sensitized by conventional methods, and can be optically sensitized to a desired wavelength range using a sensitizing dye.

Antifoggants, stabilizers, etc. can be added to the silver halide emulsion. Gelatin is advantageously used as binder for the emulsion.

The emulsion layer and other hydrophilic colloid layers can be hardened and can contain a plasticizer and a dispersion (latex) of a water-insoluble or sparingly soluble synthetic polymer.

As a support, paper laminated with polyethylene, etc.
Polyethylene terephthalate film, baryta paper, cellulose triacetate, etc. can be used.

Various known development treatments can be used to process the photosensitive material of the present invention.

〔Example〕

Examples of the present invention will be described below. Note that, as a matter of course, the present invention is not limited to the examples described below.

Comparative Example-1 (Preparation of comparative spherical seed emulsion) Monodisperse spherical seed emulsion T-1 was prepared by the following method.

A1 Ossein gelatin 150g Potassium bromide 59.3g with water
1OffiB, silver nitrate 1.5Kg Q in water 7〒) 1, Ossein gelatin Potassium bromide in water 0g 050g 2g Dl Ammonia water (28%) 705
Add Bl solution and C0 to solution A and vigorously stirred at mff40℃.
The liquid was added by a double jet method to generate nuclei.

After 1 minute and 30 seconds, the liquid was added for 20 seconds and aged for 5 minutes.

Thereafter, the pH was adjusted to 6.0, and the solution was immediately desalted and washed with water. When this seed emulsion was observed under an electron microscope, it was found to be a monodisperse spherical emulsion with an average grain size of 0.34 μm and a distribution width of 35%.

Example-1 (Preparation of spherical seed emulsion of the present invention) In Comparative Example-1, the operation was exactly the same as T-1 except that the temperature of the mixed liquid was set to 30°C before adding liquid D. A spherical seed emulsion T-2 of the present invention was prepared.

When this seed emulsion was observed under an electron microscope, the average grain size was 0.
It was a monodisperse spherical emulsion with a 25 μm distribution width of 36%.

Example 2 (Preparation of seed emulsion using spheres of the present invention) In Comparative Example 1, the procedure was exactly the same as T-1 except that the temperature of the mixed solution was set to 20°C before adding the D1 solution. A spherical seed emulsion T-3 of the present invention was prepared.

When this seed emulsion was observed under an electron microscope, the average grain size was 0.
It was a monodisperse spherical emulsion with a 2 μm distribution width of 37%.

Example-3 (Preparation of spherical seed emulsion of the present invention) In Example-2, the spherical seed emulsion T of the present invention was prepared in exactly the same manner as T-3 except that C2 liquid was added instead of CI liquid.
-4 was prepared.

When this seed emulsion was observed under an electron microscope, the average grain size was 0.
It was a monodisperse spherical emulsion with a diameter of 22 μm and a distribution width of 38%.

C1 liquid ossein gelatin 40g potassium bromide
1028g potassium iodide
2g with 30g water Comparative Example-2 (Preparation of comparative tabular seed emulsion) A comparative tabular seed emulsion was prepared using exactly the same procedure as T-3 in Example-2 except that C8 liquid was added instead of CI liquid. T
-5 was prepared.

When this seed emulsion was observed under an electron microscope, the average grain size was 0.
It was a polydisperse emulsion with a diameter of 242 μm and a distribution width of 45%.

Example-4 with C4 liquid ossein gelatin potassium bromide potassium iodide water (Preparation of Agl fine particles) 0g 40g 55g ''/8 j; S liquid gelatin Potassium iodide Sodium citrate Lium with water 2g g g 10cc T liquid Silver nitrate with 140g water
250ccU liquid potassium iodide with 147cc water
250 cc liquid silver nitrate 14 g water Added S solution to a 28 cc reaction vessel, maintained pAg = 13.0, and added T solution and U solution over 30 minutes by controlled double jet method. Thereafter, liquid Y was added in a rush to prepare Agl fine particles. The average particle size of the particles was 0.07 μm.

(Preparation of AgBr fine particles) X solution Y solution Gelatin Potassium iodide Sodium citrate 2 g in water 6.5 g g 10 cc Silver nitrate 140 g in water
250cc 2-part potassium bromide 105.4g water
250cc alpha liquid silver nitrate 14g water
Pour solution X into a 28cc reaction vessel and add pAg-
The temperature was maintained at 13.0, and liquid Y and liquid Z were added over 30 minutes using a controlled double jet method. Thereafter, U liquid was added in a rush to prepare AgBr fine particles. The average particle size of these particles was 0.06 μm.

Comparative Example 3 A comparative silver halide emulsion (Em-1) consisting mainly of tabular twins was prepared using seed emulsion T-2 (emulsion of Example 1) and the solution shown below.

El Ossein gelatin 37g Propyleneoxy polyethyleneoxydisuccinate disodium salt (10% methanol solution) lOs + Q type emulsion T
-21,14 molar phase 4000+1I2F,
Ossein gelatin Potassium bromide Potassium iodide 6g in water 51g 3g 1103■a I Ossein gelatin Potassium bromide in water 96, 5g 24g 4096+aQ H, silver nitrate 132g Water 6248s0 Stir vigorously at 75℃ E, F, liquid and H1 liquid were added by double jet method. During this period, the pH was maintained at 5.8 and I) Ag at 9.0 throughout.

After the addition, adjust the pH to 6.0 and add the following sensitizing dye (A
) and (B) each h 400s+g/Ag1 mol 15+
g/1 mol of Ag, in order to remove excess salts, precipitation desalination was performed using an aqueous solution of Demol (manufactured by Kao Atlas Co., Ltd.) and an aqueous solution of magnesium sulfate, resulting in a pAg of 8.5.
An emulsion with a pH of 5.85 was obtained at 40°C. When the obtained emulsion was observed under an electron microscope, the average grain size was 0.85μ.
The grains were tabular silver halide grains with a No. 11 distribution width of 20%, and a grain diameter/grain thickness ratio of 2.05.

Sensitizing dye (A) Sensitizing dye (B) Comparative Example-4 Using seed emulsion-3 (emulsion of Example-2) and the solution shown below, a comparative silver halide emulsion (Em -2) was prepared.

E! Ossein gelatin 37 g Propyleneoxy polyethylene oxydisacnate disodium salt (10% methanol solution) 10 m 12 type emulsion T type emulsion 3 0.583 mol equivalent water
4000mff1F, Ossein gelatin 7g Potassium bromide 55g Potassium iodide 4g Water 1135■a G, Ossein gelatin Potassium bromide 99.3g 42g H3 Silver nitrate 1165g Water 6430mQ Add F, and H2 to E, which was stirred vigorously at 75°C. It was added by double jet method. During this period, the pH was maintained at 5.8 and the pAg at 9.0 throughout. After completing the addition, perform the same operation as in Comparative Example-3.
An emulsion was obtained. When the resulting emulsion was observed under an electron microscope, it was found to be tabular silver halide grains with an average grain size of 1.0 μm and a distribution width of 22%, and an aspect ratio of 3.0.

Comparative Example 5 A comparative silver halide emulsion (Em-3) consisting mainly of tabular twin crystals was prepared using seed emulsion T-4 (emulsion of Example 3) and the solution shown below.

E, Ossein gelatin 37g Propyleneoxy polyethyleneoxydisacnate disodium salt (10% methanol solution) 10 @ 12 types of emulsion T -
30,775 moles of water equivalent to 4000 m12F.

ossein gelatin potassium bromide potassium iodide with water 25.2g 45g 22.4g 1062III2 G.

Ossein gelatin 99.8 g with potassium bromide water 45 g 4235 iff H3 Silver nitrate 1153 g Water terro 364 + n (2) F and H5 were added to E, which was vigorously stirred at 75°C, by double jet method. After the addition of F and liquid, G , the liquid was added using the double jet method. During this time, the pH was adjusted to 5.8 and the pAg
was maintained at 9.0 throughout. After the addition was completed, the same operation as in Comparative Example-3 was performed to obtain a pH of 5.5 at 40°C.
, 85 emulsions were obtained. When the obtained emulsion was observed using an electron microscope, the average grain size was 0.90 μm, and the width of the distribution was 23%.
These are tabular silver halide grains with an aspect ratio of 2.
It was 7.

Comparative Example 6 A comparative silver halide emulsion (Em-4) consisting mainly of tabular twins was prepared using seed emulsion T-1 (emulsion of Comparative Example 1) and the solution shown below.

E, Ossein gelatin 37g Propyleneoxy polyethyleneoxydisacnate disodium salt (10% methanol solution:) 10mR seed emulsion T -
4000m (1G,
Ossein gelatin 5g Potassium bromide 52g 3622m12 H6 silver nitrate 788g water
4352+aQ Vigorously stirred at 75°C, the pH of the solution was 5.8 i) Ag was 9.0
Agl fine particles and AgBr fine particles were added at a constant rate while maintaining the same temperature throughout to form a layer containing 10 mol % of silver iodide.

*G4 liquid and H4 liquid were added using the double jet method while the pH was 5.8 and pAg 9.0. After the addition was completed, the same operation as in Comparative Example 3 was performed to obtain an emulsion with pAg of 8.5 and p) of 15.85 at 40°C. When the obtained emulsion was observed under an electron microscope, it was found to be tabular silver halide grains with an average grain size of 0.85 μm and a distribution width of 18%, and an aspect ratio of 2.5.

Comparative Example 7 A comparative silver halide emulsion (Em-5) consisting mainly of tabular twins was prepared using seed emulsion T-5 (emulsion of Comparative Example 2) and the solution shown below.

E, Ossein gelatin 37g Propyleneoxy polyethylene oxydisacnate disodium salt (10% methanol solution) loi+++2 Seed emulsion T-5 1,01 mole equivalent 4000++++2 in water G, Ossein gelatin 00g Potassium bromide 54g 294mQ in water H6 silver nitrate 959g with water
5300mQ The pH of the H5 solution was vigorously stirred at 75 DEG C. and the pAg was maintained at 9.0 throughout. Agl fine particles and AgBr fine particles were added at the same speed to form a layer containing 10 mol % of silver iodide. Then pH5
, 8 mil Ag9.0, liquid G5 and liquid H5 were added by double jet method. After the addition was completed, the same operation as in Comparative Example 3 was carried out, and p A g was 8-5. p at 40°C.
An emulsion of H5,1lI5 was obtained. When the obtained emulsion was observed under an electron microscope, it was found to be tabular silver halide grains with an average grain size of 0.85 μm and a distribution width of 30%, and an aspect ratio of 2.5.

Example 5 A silver halide emulsion i (Em-6) of the present invention consisting mainly of tabular twin crystals was prepared using seed emulsion T-2 and the solution shown below.

H6 silver nitrate 892g with water
4923 + ff Vigorously stirred at 75°C, the pH of the solution was adjusted to 5.8 i) Ag was 9.0
Agl fine particles and AgBr fine particles were added at a constant rate while maintaining the same temperature throughout to form a layer containing 10 mol % of silver iodide. then p
Liquid G1 and liquid H were added using a double jet method with H5.8 and pAg 9.0. After the addition was completed, the same operation as in Comparative Example-3 was carried out to obtain pAg of 8.5 and p at 40°C.
An emulsion of H5,85 was obtained. When the obtained emulsion was observed under an electron microscope, the average grain size was 1.2 μm5 and the width of the distribution was 18
% tabular silver halide grains with an aspect ratio of 5.
．． It was 0.

Example 6 Using seed emulsion T--3 and the solution shown below, a halogenated emulsion of the present invention consisting mainly of tabular twins (E m -7) was prepared.
) was adjusted.

H7 silver nitrate 917g with water
E was stirred vigorously at 5060 m 1275°C, and A was kept at pHSpAg of 9.0.
GL fine particles and AgBr fine particles were added at a constant rate to form a layer containing % iodide. Thereafter, I) Liquid G2 and Liquid H7 were added using a double jet method with H5.8 and pAg 9.0.

After completing the addition, perform the same operation as in Comparative Example-3 to obtain pAg
8.5. An emulsion with a pH of 5.85 was obtained at 40°C. When the obtained emulsion was observed under an electron microscope, the average grain size was 1.
．． The grains were tabular silver halide grains with a 4 μm distribution width of 18%, and the grain diameter/grain thickness ratio was 7.0.

Example 7 A silver halide emulsion (Em-8) of the present invention comprising mainly tabular twin crystals was prepared using seed emulsion T-4 and the solution shown below.

H, silver nitrate 945g in water
5217 Peng A Agl fine particles and AgBr fine particles were added in equal amounts while keeping the pH of the solution at 5.8 and PAG 9.0 throughout with vigorous stirring at 75°C to form a layer containing 10 mol% of silver iodide. Ta. Then pH 5-
8. Liquid G and liquid H8 were added using a double jet method with the pAg kept at 9.0. After the addition was completed, the same operation as in Comparative Example-3 was performed to obtain a pH of 5.5 at 40°C.
85 emulsions were obtained. When the obtained emulsion was observed under an electron microscope, it was found to be tabular silver halide grains with an average grain size of 1.3 μm and a distribution width of 19%, and an aspect ratio of 5.7.

Example 8 For each emulsion, sensitizing dyes (A) and (B) were each added at 140 gs per mole of silver immediately before adding the chemical sensitizer.
3 mg was added.

After the chemical ripening was completed, various additives described below were added.

The additives used in the emulsion liquid (photosensitive silver halide coating liquid) are as follows. The amounts added are: halogenated t-butyl-techol polyvinylpyrrolidone (molecular weight 10.000) styrene-maleic anhydride copolymer trimethylolpropane diethylene glycol nitrophenyl-triphenylphosphonium chloride 1,3-dihydroxybenzene-4-ammonium sulfonate Sodium 2-methylcaptobenzimidazole-5-sulfonate 00 mg 1.0 g 2.5 g 0 g 5 g 50 g 1.5 mg OH The additives used in the protective layer solution are as follows.

The amount added is expressed per 1 g of gelatin.

Matting agent made of polymethyl methacrylate with silicon dioxide particles having an area average particle size of 7 μm 7B colloidal silica (average particle size of 0.013 μm) 70rmg2
．． 4-dichloro-6-hydroxy-1,3,5-triazine sodium salt 30B (
C1t, -CO2O3-CHIM
3
6mgCHzCOO(CH2)zcH3 CHCOO(CHz)zcH(CHs)zB SO, Na Na03s CHC00C[(2(C2F4)3HC
HzCOOCHz(CJ4)sH5”gF 1*C*
0fcH2c[(go force τcH2cH20H3m g
Bis(vinylsulfonylmethyl)ether gelatin 1g
Samples 1 to 8 were prepared by applying 7 mg or more of the coating liquid to both sides of a polyethylene terephthalate film base colored blue and undercoated to a thickness of 180 μI, and drying it. .

All samples were adjusted so that the coated gelatin amount was 3.0 g/+o'' on both sides and the coated silver amount was 4.5 g/+''.

[Evaluation of sensitivity]

B. The obtained sample was sandwiched between X-ray photographic intensifying screens [0-250], and after X-ray irradiation through a Venetrometer type B, 5RX-5
01 automatic processor at 35°C with XD-3R processing solution.
Processing was performed for 45 seconds. (All manufactured by Konica Corp.) The sensitivity of each sample developed as described above was evaluated. Sample 1 is the best in terms of sensitivity! J+1. It is expressed as a relative value with the reciprocal of the amount of explosive energy required to give the concentration of Q as 100.

(Evaluation of pressure resistance) Each sample was heated for about 12 hours at 25°C and 50RH% (7) [! L
[li! : Under these conditions, the radius of curvature is approximately 2c.
800 folds. Three minutes after bending, exposure was performed using an optical wedge and development was performed. The darkening density of each wedge of this sample was measured, and the density difference between the desensitized part caused by bending and the part not bent was defined as △D,
Divide ΔD by each concentration to calculate the average value ΔD/D, and the smaller this value is, the better the resistance to pressure desensitization is.

The results are shown in Table-1.

Table = 1 From the results in Table 1, it can be seen that all the samples of the present invention have low fog and high sensitivity, and also have good pressure desensitization resistance.

〔Effect of the invention〕

According to the present invention, it was possible to provide a silver halide photographic material with low fog, high sensitivity, and excellent resistance to pressure desensitization.

Claims (2)

[Claims] (1) In the method for producing silver halide grains (A) in which 50% or more of the projected area has a grain diameter/grain thickness ratio of 2 or more, the silver iodide grains are Ostwald-ripened at 39°C or less after nucleation. These are silver halide grains grown using spherical grains of 2 mol % or less as a seed emulsion, and the solubility product is higher than that of the grown grains (A) prepared in advance in a reaction vessel in which the grains (A) are grown. A silver halide photographic light-sensitive material characterized by containing silver halide grains obtained by adding small and fine-sized silver halide grains (B). (2) The silver halide grains (B) having a smaller solubility product than the growing grains (A) and having a fine size are silver iodide, silver bromide, or silver chloride. Photographic material.