JPH11143002A - Manufacture of flat silver halide grains - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the manufacture of an emulsion comprising a gelatin and flat silver halide grains in a monodispersion, i.e., narrow in a projection circle diameter distribution and small in a grain thickness and high in an aspect ratio of grains by using a gelatin having carboxylic groups introduced in a specified amount at the time of chemically modifying the amino groups of the gelatin molecule used as a dispersion medium. SOLUTION: The flat silver halide grains are formed in the presence of the gelatin with at least 2 carboxylic acid groups (-COOH) substituted for the amino groups (-NH3 ) introduced at the time of chemically modifying the amino groups of the gelatin. These amino groups of thus gelatin are modified with trimellitic acid anhydride or pyromellitic acid anhydride in a modification rate of >=50% of the amino groups. This dispersion medium contains at least one of polymers having repeating units represented by the formula: -(R-O)n - in which R is a 2-10C alkylene group, and (n) is an average number of repeating units of 4-200.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a silver halide emulsion,
In particular, it relates to a method for producing a silver halide tabular grain emulsion for photography.

[0002]

2. Description of the Related Art Silver halide grains containing two or more twin planes in parallel have a tabular form. (Hereinafter "tabular grain")
Call. ) These tabular grains have the following photographic properties: 1) Ratio of surface area to volume (hereinafter referred to as specific surface area)
And a large amount of sensitizing dye can be adsorbed on the surface. As a result, the color sensitization sensitivity is relatively high. 2) When an emulsion containing tabular grains is coated and dried, the grains are arranged in parallel to the surface of the support, so that light scattering by the grains can be reduced and sharpness and resolution can be improved. In addition, the thickness of the coating layer can be reduced by this arrangement, and the sharpness can be improved. 3) Since the specific surface area is large, development can be accelerated. 4) High covering power enables silver saving. Because of these many advantages, they have been used in high-sensitivity commercial photosensitive materials. JP-A-58-113926
Nos. 58-113927 and 58-113928 disclose emulsion grains having an aspect ratio of 8 or more. Here, the aspect ratio is indicated by a ratio of a diameter to a thickness of a tabular grain. Further, the diameter of a particle indicates the diameter of a circle having an area equal to the projected area of the particle (hereinafter, referred to as a projected area diameter). The thickness is indicated by the distance between two parallel main surfaces constituting the tabular grains.

Further, since tabular grains having a larger aspect ratio have a larger specific surface area, the above-mentioned advantages of tabular grains can be greatly utilized. Various attempts have been made to reduce the thickness of tabular grains in order to increase the aspect ratio. Japanese Patent Publication No. 5-12696 discloses a method for preparing tabular grains having a small thickness using gelatin in which a methionine group in gelatin has been invalidated with hydrogen peroxide or the like as a dispersion medium. Japanese Patent Application Laid-Open No. 8-82883 discloses a method for preparing thin tabular grains using gelatin in which amino groups and methionine groups have been invalidated as a dispersion medium. U.S. Pat. No. 5,380,642 and Japanese Patent Application No. 7-117684 disclose a method for preparing thin tabular grains using a synthetic polymer as a dispersion medium.

Various attempts have been made to monodisperse tabular grains, and several patents have been disclosed.
For example, JP-A-52-153428, JP-A-55-142329, JP-A-51-39027, JP-A-61-112142, French Patent No. 253
No. 4036. Also, JP-A-63-11928, 63-1
No. 51618 and JP-A-2-838 disclose monodispersed tabular grains containing hexagonal tabular grains. Unlike hexagonal tabular grains, these hexagonal tabular grains are monodisperse tabular grains in which the ratio of tabular grains having two parallel twin planes to the total projected area is 99.7% and the coefficient of variation of the equivalent circle diameter is 10.1%. There is a description of particles. However, tabular grains having a small thickness and a large aspect ratio have a wide distribution of projected area diameters, making it difficult to obtain a monodispersed emulsion. On the other hand, U.S. Pat.
No. 5171659, No. 5147772, No. 5147773, and EP 514742A, discloses a production method for obtaining monodisperse tabular grains by allowing a polyalkylene oxide block copolymer to be present at the time of nucleation, and has a coefficient of variation. Is described as 4.7% monodisperse tabular grains. In addition, JP-A-7
-28183 and 7-98482 also disclose methods for preparing monodisperse tabular grains using synthetic polymers. These techniques have achieved a small thickness and excellent monodispersity in the AgBr system, but it has been difficult to achieve both monodispersity and thinning in the AgBrI system.

[0005]

In view of the above, an object of the present invention is to produce an emulsion comprising tabular grains having a small thickness (ie, a large aspect ratio) and a monodisperse distribution of projected area diameters. It is to provide a way to do it.

[0006]

The object of the present invention has been attained by the following items. (1) A silver halide tabular grain is converted into an amino group (—NH
₍₂ ) is chemically modified in the presence of gelatin into which at least two carboxyl groups (-COOH groups) have been newly introduced instead of amino groups. (2) Gelatin newly carboxyl group in an amino group in the gelatin molecule (-NH ₂ group) chemically modified (-COOH group) is introduced at least two or more, trimellitic anhydride modification of amino groups The method for producing a silver halide emulsion according to the above (1), wherein the method is carried out using an emulsion. (3) Gelatin into which at least two carboxyl groups (-COOH groups) have been newly introduced when the amino groups (-NH ₂ groups) in the gelatin molecules are chemically modified, the amino groups are modified by pyromellitic anhydride. The method for producing a silver halide emulsion according to the above (1), wherein the method is carried out using an emulsion. (4) The method for producing a silver halide emulsion as described in (1), (2) or (3) above, wherein the modification ratio of the amino group in the gelatin molecule is 50% or more. (5) The method for producing tabular silver halide grains according to (1), wherein the dispersion medium contains at least one kind of a polymer having a repeating unit represented by the following general formula (1). Formula (1)-(RO) _n -wherein R represents an alkylene group having 2 to 10 carbon atoms.
n represents the average number of repeating units, and represents 4 or more and 200 or less.

[0007] The silver halide emulsion thus obtained is a silver halide emulsion comprising a dispersion medium and silver halide grains, and has a total projected area of 80%.
% Or more is occupied by tabular grains having two or more twin planes parallel to the main plane, and the tabular grains have a hexagonal shape and the size distribution of the tabular grains is monodisperse. It is assumed that. The hexagonal tabular grains referred to in the present invention are:
Tabular grains in which the ratio of the lengths of two adjacent sides of six sides forming a hexagon are 2 or less. The thickness of the hexagonal tabular grains of the present invention is from 0.01 μm to 0.2 μm, preferably from 0.02 μm to 0.15 μm. The hexagonal tabular grains of the present invention are monodisperse, and the monodispersity referred to herein is represented by a variation coefficient of a projected area diameter. The monodispersity of the tabular grains of the present invention is a coefficient of variation of 30% or less, preferably 5 to 25%. The average aspect ratio of the hexagonal tabular grains of the present invention is from 2 to 60, preferably from 3 to 50. Here, the average aspect ratio means an average value of aspect ratios of all tabular grains having a diameter of 0.2 μm or more present in the emulsion.

First, the amino group-modified gelatin mainly used in the present invention will be described. Amino group-modified gelatin used for tabular grain formation is described in JP-A-8-82883. In the invention, a primary amino group (—NH ₂ ) is
Tabular grains having a small thickness have been obtained by tertiary amino groups (-NH-), tertiary amino groups, or deamination.
In the invention, when an acid anhydride, for example, phthalic anhydride, succinic anhydride, or maleic anhydride is reacted, the amino group is modified and one —COOH group is introduced instead of one —NH ₂ group. In the present invention, focusing on the introduced -COOH groups and increasing the number of introduced -COOH groups, the effect of further reducing the thickness of tabular grains was observed. This phenomenon is considered as follows. The carboxyl group (-COOH group) is usually dissociated at pH 4 or higher to form -COOH
O ^- it has become. Generally, silver halide grains are formed in a region where silver ions are excessive in silver ions, and it is considered that halogen ions are adsorbed on the surface of silver halide grains (E. Moisar and E. Klein, Bunsenges.P
hys. Chem. 67,949 (1963)). Therefore, -COO negatively charged in gelatin molecule ^- and the halogen ions of the silver halide surface can be considered that the adsorption to silver halide grains the gelatin molecule is reduced by repulsion (Suzuki, Morita,
Nishio, Journal of the Photographic Society of Japan, 58, 25 (1995)). When it is considered that the growth of the tabular grains in the lateral direction is changed by the adsorption power of gelatin, it is considered that the thickness of the tabular grains becomes smaller as the gelatin adsorption power decreases. Further, when the gelatin of the present invention was used for growing tabular grains, tabular grains having a small thickness and a narrow distribution of projected area diameter were obtained. Specific procedures for the introduction of the -COOH group, a method of modifying an amino group (-NH ₂₎ can be taken by adding a reaction reagent to gelatin. Specific examples of the reagent are given below, but are not limited thereto. A compound having at least two or more carboxylic acids (-COOH), the structure of which forms at least one acid anhydride. For example, trimellitic anhydride, pyromellitic anhydride, melitic anhydride and the like can be mentioned. At least a compound having two or more carboxylic acids,
A compound having at least one cyanate in its structure. For example, phenyl isocyanate and the like can be mentioned. At least a compound having two or more carboxylic acids,
A compound having at least one aldehyde or ketone in its structure. At least a compound having two or more carboxylic acids,
A compound having at least one imide ester in its structure. In addition, in the modification reaction of the amino group, the gelatin molecule may be crosslinked to increase the molecular weight. For example, in the production of pyromellitic gelatin, gelatin molecules may be crosslinked by a change in conditions such as gelatin concentration during the reaction. In the present invention, gelatin molecules at the time of such amino group modification may or may not have a high molecular weight. Amino group (-NH
₂ ) is determined by the -N of lysine residue in the gelatin molecule.
H ₂ group (ε-NH ₂ group) 50% or more with respect to, preferably 70% or more, more preferably 90% or more, the total -NH ₂ group in the gelatin molecule (α-NH ₂ group, epsilon -NH
₍₂ groups, guanidyl group) is 30% or more, preferably 50% or more.

An example of the method for producing the modified gelatin of the present invention will be described below, but it should not be construed that the invention is limited thereto. For the modification of amino groups, various techniques have been developed since ancient times.
For example, U.S. Patent Nos. 2,525,573, 3,118,766, and 261492
No. 8, 2614929, Japanese Patent Publication No. 40-15585, JP-A-8-82883
And the descriptions in the Photographic Society of Japan, vol. 58, p. 25 (1995), etc. can be referred to. The method for producing trimellitated gelatin, one of the gelatins of the present invention, is described in Journal of the Photographic Society of Japan.
The following method described in Vol. 58, p. 25 (1995) can be referred to. After adjusting the pH of the 15% aqueous gelatin solution kept at 60 ° C. to 9.0, an aqueous trimellitic anhydride solution was added. During the reaction, the pH is maintained at 8.75 to 9.25, and the reaction is carried out for 1 hour. After completion of the reaction, a deionization treatment was performed by ultrafiltration. After adjusting the pH to 6.0, the mixture is dried to obtain a gelatin powder. In addition, an example of a method for producing pyromellitic gelatin, which is one of the gelatins of the present invention, is shown below. After adjusting the pH of the 15% aqueous gelatin solution kept at 60 ° C. to 9.0, an aqueous solution of pyromellitic anhydride was added. PH during reaction
From 8.75 to 9.25 and allowed to react for 1 hour. After completion of the reaction, a deionization treatment was performed by ultrafiltration. After adjusting the pH to 6.0, the mixture is dried to obtain a gelatin powder.

Next, the polymer used in the silver halide emulsion of the present invention will be described in detail. The polymer used for forming the tabular grain emulsion of the present invention is a polymer having a repeating unit represented by the following general formula (1). Formula (1)-(RO) _n -wherein R represents an alkylene group having 2 to 10 carbon atoms.
n represents the average number of repeating units, and represents 4 or more and 200 or less. In forming the emulsion of the present invention, it is preferable to use a repeating unit of the general formula (1), but it is preferable to use at least one monomer represented by the following general formula (2). A vinyl polymer as a component or a polyurethane represented by the following general formula (3) is preferably used, and a vinyl polymer having a repeating unit represented by the general formula (2) is particularly preferable. General formula (2)

[0011]

Embedded image

General formula (3)

[0013]

Embedded image

In the formula, R represents an alkylene group having 2 to 10 carbon atoms. n represents the average number of repeating units, and represents 4 or more and 200 or less. R ¹ is a hydrogen atom, a lower alkyl group,
R ² represents a monovalent substituent, and L represents a divalent linking group.
R ³ and R ⁴ are an alkylene group having 1 to 20 carbon atoms, a phenylene group having 6 to 20 carbon atoms, or a C ⁷ to C 2
Represents an aralkylene group of 0. x, y, z represent the weight percentage of each component, x is 1 to 70, y is 1 to 70,
z represents 20 to 70. Here, x + y + z = 10
0.

Specific examples of the polymer used in the present invention are shown below, but the polymer of the present invention is not limited to these. Further detailed examples and general descriptions are described in Japanese Patent Application No. 8-113454.

[0016]

Embedded image

[0017]

Embedded image

[0018]

Embedded image

[0019]

Embedded image

[0020]

Embedded image

Preferred examples of the polymer having a repeating unit represented by the general formula (1) of the present invention include polyalkylene oxide block polymers represented by the following general formulas (4) and (5). Can be General formula (4)

[0022]

Embedded image

Formula (5)

[0024]

Embedded image

In the formula, R ⁵ represents a hydrogen atom, an alkylene group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms;
n represents an integer of 1 to 10. Here, when n = 1,
R ⁹ cannot be a hydrogen atom. R ⁶ represents a hydrogen atom or a lower alkyl group having 4 or less carbon atoms and substituted by a hydrophilic group. x and y are the number of repetitions of each unit (number average degree of polymerization)
Represents

Specific examples of the block polymer used in the present invention are shown below, but the polymer of the present invention is not limited to these. More detailed examples,
General descriptions are given in European Patents 513722, 513723, 51
3724, 513735, 513742, 513743, 5180
No. 66, Japanese Patent Application No. 8-113454.

[0027]

Embedded image

[0028]

Embedded image

[0029]

Embedded image

Next, a method for producing the silver halide emulsion of the present invention will be described. The silver halide emulsion of the present invention can be produced in the process of nucleation → ripening → growth. The gelatin of the present invention is preferably present at least before growth during grain formation, preferably immediately after nucleation, and more preferably before nucleation. The amount is at least 60%, preferably at least 80%, more preferably at least 90%, based on the total dispersion medium during the formation of the particles. When the gelatin of the present invention is used, monodisperse tabular grains having a small thickness can be obtained. In addition, the monodispersity can be increased by the presence of the water-soluble polymer represented by the general formula (1) during the formation of particles using the gelatin of the present invention. When the water-soluble polymer represented by the general formula (1) is present during grain formation, it may be present anywhere during grain formation, but at least before growth, preferably before ripening, and more preferably nucleus. Desirably, it is present before formation. The amount thereof can be 0.1 to 50 times, preferably 0.1 to 30 times, by weight, based on silver nitrate used for nucleation.

The nucleation, ripening, and growth processes will be described below. 1. Nucleation Nucleation of tabular grains is generally performed by adding a silver salt aqueous solution and an alkali halide aqueous solution to a reaction vessel holding an aqueous solution of gelatin, or by a double jet method, or by adding a silver salt to a gelatin solution containing an alkali halide. A single jet method in which an aqueous solution is added is used. Further, a method of adding an aqueous solution of an alkali halide to a gelatin solution containing a silver salt, if necessary, can also be used. Further, if necessary, a gelatin solution, a silver salt solution and an aqueous alkali halide solution are added to a mixer disclosed in JP-A-2-44335, and the mixture is immediately transferred to a reaction vessel to form nuclei of tabular grains. Can also be performed. Also, U.S. Pat.
As disclosed in 04786, nucleation can also be carried out by passing an aqueous solution containing an alkali halide and a protective colloid solution through a pipe and adding an aqueous silver salt solution thereto. For nucleation, gelatin was used as a dispersion medium and pBr was 1 to
It is preferable to form a dispersion medium under the condition of 4. As the kind of gelatin, it is preferable to use the gelatin of the present invention. However, alkali-treated gelatin, low-molecular-weight gelatin (molecular weight: 3000 to 40,000), or oxidized gelatin may be used. Gelatin may be used at the same time. When used simultaneously, the gelatin of the present invention accounts for at least 20%, preferably at least 50%, more preferably at least 80%, based on the total dispersion medium. The concentration of the dispersion medium is preferably 10% by weight or less, more preferably 1% by weight or less. The temperature at the time of nucleation is preferably 5 to 60 ° C, but more preferably 5 to 48 ° C in the case of producing fine tabular grains having an average particle size of 0.5 µm or less. The pH of the dispersion medium is
When the gelatin of the present invention is used, it is preferably 4 or more and 10 or less, but when other gelatin is used, it is 2 or more and 10 or less.
The following is preferred. The composition of alkali halide solution added, Br ^- for I ^- content generates AgB
It is not more than the solid solution limit of rI, preferably not more than 10 mol%.

2. Aging 1. In the nucleation in (1), fine particles other than tabular grains (particularly, octahedral and single twin grains) are formed. Prior to the growth process described below, it is necessary to eliminate grains other than tabular grains to obtain nuclei having a shape to be tabular grains and having good monodispersity. To make this possible, it is well known to carry out Ostwald ripening following nucleation. Immediately after the nucleation, pBr is adjusted, and the temperature is increased to ripen until the hexagonal tabular grain ratio becomes maximum. At this time, a gelatin solution may be additionally added. At that time, the concentration of gelatin in the dispersion medium solution is preferably 10% by weight or less. The additional gelatin used at this time is
Although it is preferable to use the gelatin of the present invention, alkali-treated gelatin and oxidized gelatin may be used. The aging temperature is 40 to 80 ° C, preferably 50 to 80 ° C,
pBr is 1.2 to 3.0. The pH is preferably 4 or more and 10 or less when the gelatin of the present invention is present,
In the case of other gelatin, it is preferably 2 or more and 8 or less.
At this time, a silver halide solvent may be added in order to quickly eliminate grains other than tabular grains. In this case, the concentration of the silver halide solvent is preferably 0.3 mol / liter or less, more preferably 0.2 mol / liter or less. When used as an emulsion for direct reversal, a silver halide solvent such as a thioether compound or the like used on a neutral or acidic side is more preferable as a silver halide solvent than NH ₃ used on an alkaline side. Aged in this way, almost ~ 100
% Tabular grains only. After ripening, if the silver halide solvent is unnecessary in the next growth process, the silver halide solvent is removed as follows. In the case of an alkaline silver halide solvent such as NH ₃ , an acid having a large solubility product with Ag ⁺ such as HNO ₃ is added to nullify the solvent. In the case of a thioether-based silver halide solvent,
As described in JP-A-60-136736, the reaction is nullified by adding an oxidizing agent such as H ₂ O ₂ .

3. The pBr during the crystal growth period following the ripening process is preferably maintained at 1.4 to 3.5. If the gelatin concentration in the dispersion medium solution before the growth process is low (1% by weight or less), gelatin may be additionally added. At that time, the gelatin concentration in the dispersion medium solution is preferably set to 1 to 10% by weight.
The gelatin used at this time is the gelatin of the present invention. The pH during growth is 4 or more and 10 or less, preferably 5 or more and 8 or less. The addition rate of Ag ⁺ and halogen ions during the crystal growth period is 20 to 100 of the critical crystal growth rate.
%, Preferably 30 to 100%. In this case, the addition rates of silver ions and halogen ions are increased with the growth of the crystal. In this case, as described in JP-B-48-36890 and JP-B-52-16364, the addition rates of silver salt and halogen salt aqueous solutions are increased. May be increased, and the concentration of the aqueous solution may be increased. During the growing period, the iodine content of AgX deposited on the nucleus is preferably from 0 mol% to the solid solution limit concentration.

The silver halide in the present invention is, for example, silver bromide, silver iodobromide, silver chlorobromide having a silver chloride content of 30 mol% or less, silver chloroiodobromide and the like. Other constitutions of the emulsion layer of the silver halide photographic light-sensitive material of the present invention are not particularly limited, and various additives can be used as needed. Chemical sensitizers, spectral sensitizers, antifoggants, metal ion dopants, silver halide solvents, stabilizers, dyes, color couplers, DIR couplers, binders, hardeners, coating aids, which can be added, Thickeners, emulsion sedimentants, plasticizers, dimensional stability improvers, antistatic agents, fluorescent brighteners, lubricants, surfactants, ultraviolet absorbers, scattering or absorbing materials, hardeners, anti-adhesion, photographic properties improvement Photographically advantageous fragments (development inhibitors or accelerators, bleaching accelerators, developers, silver halide solvents, toners, hardeners, antifoggants) Agents, competitive couplers, chemical or spectral sensitizers and desensitizers)
Releasing couplers, image dye stabilizers, self-suppressing developers,
And its use, also supersensitization in spectral sensitization, halogen acceptor effect and electron acceptor effect of spectral sensitizing dye, antifoggant, stabilizer, action of development accelerator or inhibitor,
In addition, a production apparatus, a reaction apparatus, a stirring apparatus, a coating method, a drying method, an exposure method (light source, an exposure atmosphere, an exposure method) used for producing the emulsion of the present invention, a photographic support, a microporous support, an undercoat layer, For the surface protective layer, matting agent, intermediate layer, antihalation layer, layer structure of AgX emulsion, photographic processing agent and photographic processing method, Research Disclosure, 17
6, 1978, December issue (item 17643),
Volume 184, August 1979 issue (item 18431),
Vol. 134, June 1975 (item 13452),
Product Licensing Index Magazine Volume 92 1
07-110 (December 1971), JP-A-58-113926
~ 113928, 61-3134, 62-6251, JCIA Monthly Report 1
December 984, pages 18 to 27, JP-A-62-219982
No., THJames, The Theory of The Photographic Proce
ss, Fourth Edission, Macmillan, New York, 1977,
Making and Coating Photograp by VLZelikman et al.
The description of hic Emulsion (The Focal Press, 1964) can be referred to. One or more silver halide emulsions of the present invention can be provided on a support together with other emulsions, if necessary. Further, the support can 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 is a black-and-white silver halide photographic material (for example, X
Ray-sensitive material, squirrel-type material, negative film for black and white photography, etc.)
And color photographic materials (eg, color negative film,
Color reversal film, color paper, etc.). Further, it can be used as a light-sensitive material for diffusion transfer (for example, a color diffusion transfer element, a silver salt diffusion transfer element), and a heat-developable light-sensitive material (black and white, color). Next, the present invention will be described in more detail by way of examples, but embodiments of the present invention are not limited thereto.

[0035]

EXAMPLES (Comparative Example 1) One liter (pH = 5) of a dispersion medium solution containing 0.38 g of KBr and 0.5 g of low molecular weight gelatin (molecular weight: 15000) was kept at 40 ° C. in a reaction vessel and stirred. Then, by a double jet method, 0.29 mol / l of silver nitrate solution and the same 0.29 mol / l of KBr solution were each added in an amount of 20 cc.
Added in 0 seconds. After the addition, this dispersion medium solution was heated to 75 ° C. over 15 minutes. 15 minutes after the temperature was raised, a dispersion medium solution (A) containing 35 g of alkali-treated gelatin and 250 cc of water was newly added. At this time, the pH was adjusted to 6. After this, 734 cc of a 1.2 mol / liter silver nitrate solution was accelerated at a flow rate.
Was added. During this time, pBr is kept at 2.93 so that K
The Br solution was added at the same time. (Comparative Example 2) Particle formation was performed in the same manner as in Comparative Example 1 except that a dispersion medium solution containing 35 g of oxidized gelatin and 250 cc of water was used instead of the dispersion medium solution (A). . Here, the oxidized gelatin is obtained by oxidizing alkali-processed gelatin with hydrogen peroxide to completely oxidize methionine in gelatin. Comparative Example 3 Particle formation was performed in the same manner as in Comparative Example 1 except that a dispersion medium containing 35 g of phthalated gelatin and 250 cc of water was used instead of the dispersion medium solution (A).
Here, the phthalated gelatin is obtained by replacing 98% of amino groups in alkali-treated gelatin with phthalic anhydride. (Example 1) The present invention In Comparative Example 1, particles were formed in the same manner as in Comparative Example 1 except that a dispersion medium containing 35 g of trimellitated gelatin and 250 cc of water was used instead of the dispersion medium solution (A). went. Here, the trimellitated gelatin is obtained by substituting 99% of the amino group in the alkali-treated gelatin with trimellitic anhydride. (Example 2) The present invention In Comparative Example 1, particles were formed in the same manner as in Comparative Example 1 except that a dispersion medium containing 35 g of pyromellitic gelatin and 250 cc of water was used instead of the dispersion medium solution (A). went. Here, pyromellitic gelatin is obtained by substituting 99% of amino groups in alkali-treated gelatin with pyromellitic anhydride. Each of the particles obtained in (Comparative Example 1), (Comparative Example 2), (Comparative Example 3), (Example 1), and (Example 2) has a hexagonal shape whose main plane is a {111} plane. AgBr tabular grains. The size and size distribution are shown in (Table 1). Further, (Comparative Example 1), (Comparative Example 2), and (Example 1)
A replica photograph of the particles obtained in (1) is shown in FIG. Compared to the phthalated gelatin used in (Comparative Example 3), the trimellited gelatin of the present invention (Example 1) has a smaller number of carboxyl groups introduced instead of the amino group when the amino group is substituted. Is 2 times, and that of the pyromellitic gelatin in Example 2 is 3 times. As can be seen from Table 1, the thicknesses of the tabular grains of the trimellitated gelatin and the pyromelliticized gelatin were smaller than those of the phthalated gelatin of the prior art. This indicates that the larger the number of carboxyl groups introduced by amino group substitution, the lower the adsorptivity of gelatin molecules and the smaller the thickness of tabular grains. Furthermore, in the case of the oxidized gelatin of the prior art, the thickness of the tabular grains was reduced, but the distribution of the projected area diameter was widened. However, the trimellitated gelatin and the pyromellitic gelatin of the present invention have tabular grain thicknesses equal to or less than oxidized gelatin,
A feature is that a projection area diameter distribution is narrow.

[0036]

[Table 1]

Comparative Example 4 One liter (pH = 5) of a dispersion medium solution containing 0.38 g of KBr and 0.5 g of low-molecular-weight gelatin (molecular weight: 15000) was kept at 40 ° C. in a reaction vessel, and the mixture was stirred. By double jet method, 20cc each of 0.29mol / L silver nitrate solution and 0.29mol / L KBr solution,
Added over 40 seconds. After the addition, this dispersion medium solution was heated to 75 ° C. over 15 minutes. 15 minutes after the temperature was raised, a dispersion medium solution (A) containing 35 g of alkali-treated gelatin and 250 cc of water was newly added. At this time, the pH was adjusted to 6. After this, 734 cc of a 1.2 mol / liter silver nitrate solution was accelerated at a flow rate.
Was added. During this time, pBr is kept at 2.93 so that K
A mixed solution of a Br solution and a KI solution was added at the same time. At this time, the KI solution in an amount of 3 mol% with respect to the added silver amount is
Had been mixed with the Br solution. Comparative Example 5 Particle formation was performed in the same manner as in Comparative Example 4 except that a dispersion medium solution containing 35 g of oxidized gelatin and 250 cc of water was used instead of the dispersion medium solution (A). . Here, the oxidized gelatin is obtained by oxidizing alkali-processed gelatin with hydrogen peroxide to completely oxidize methionine in gelatin. (Example 3) The present invention Comparative Example 4 was repeated except that a dispersion medium containing 35 g of trimellitated gelatin and 250 cc of water was used instead of the dispersion medium solution (A). went. Here, the trimellitated gelatin is obtained by substituting 99% of the amino group in the alkali-treated gelatin with trimellitic anhydride. (Example 4) The present invention was carried out in the same manner as in Comparative Example 4 except that a dispersion medium containing 35 g of pyromellitic gelatin and 250 cc of water was used instead of the dispersion medium solution (A). went. Here, pyromellitic gelatin is obtained by substituting 99% of amino groups in alkali-treated gelatin with pyromellitic anhydride. Particles obtained in (Comparative Example 4), (Comparative Example 5), (Example 3), and (Example 4) each had a principal plane of # 11.
It was hexagonal AgBrI tabular grains having 1｝ faces. The size and size distribution were as shown in (Table 2). When the trimellitated gelatin and the pyromellitized gelatin of the present invention were used, monodisperse tabular grains having a small thickness were obtained.

[0038]

[Table 2]

Example 5 The procedure of Example 1 was repeated, except that, immediately after the temperature was raised to 75 ° C., 50 cc of a 4% aqueous solution of the synthetic polymer (P-1) of the present invention was added and the pH was adjusted to 9.
The same steps as in Example 1 were performed. (Example 6) In Example 1, immediately after the temperature was raised to 75 ° C.,
50% of a synthetic polymer of the present invention (PLURONIC TM31R1 manufactured by BASF: corresponding to compound B-1 of the present invention) in the form of a 22% aqueous solution
The same steps as in Example 1 were performed, except that c was added and the pH was adjusted to 9. Each of the grains obtained in Examples 5 and 6 was a hexagonal AgBr tabular grain having a {111} major plane, and the size and size distribution were as shown in (Table 3).

[0040]

[Table 3]

(Example 7) The emulsion A obtained in Example 7 was subjected to chemical sensitization and spectral sensitization to give a light-sensitive material of Sample 6 (Sample No. 101) of Example 3 of JP-A-6-258788. Used for the fifth layer of
Good performance was obtained by performing the same processing as in this example. (Example 8) The emulsion A obtained in Example 7 was subjected to chemical sensitization and spectral sensitization to give a light-sensitive material X of Example 1 of JP-A-6-273866.
And used in the same manner as in Example 1 in combination with Screen B to obtain good performance. (Example 9) The emulsion A obtained in Example 7 was subjected to chemical sensitization and spectral sensitization to give Example 1 of JP-A-2-854 (Sample No. 10).
Good results were obtained by performing the same treatments as in this example, using the sixth layer of the light-sensitive material of 1).

[Brief description of the drawings]

FIG. 1 is an electron micrograph showing the crystal structure of silver halide grains of Comparative Example 1, and the magnification is 3,300.

FIG. 2 is an electron micrograph showing the crystal structure of silver halide grains of Comparative Example 2, and the magnification is 3,3000 times.

FIG. 3 is an electron micrograph showing the crystal structure of the silver halide grains of Example 1, and the magnification is 3,300.

Claims (7)

[Claims] 1. A method for producing silver halide tabular grains in a dispersion medium solution, wherein the dispersion medium newly forms a carboxyl group (-NH ₂ group) when chemically modifying an amino group (—NH ₂ group) in a gelatin molecule. A method for producing a silver halide emulsion, comprising gelatin into which at least two or more -COOH groups have been introduced. 2. An amino group (-NH) in a gelatin molecule.
New carboxyl group ₂ group) upon chemical modification (-C
2. The method for producing a silver halide emulsion according to claim 1, wherein the amino group of the gelatin into which at least two OOH groups have been introduced is modified using trimellitic anhydride. 3. An amino group (—NH) in a gelatin molecule.
New carboxyl group ₂ group) upon chemical modification (-C
2. The method for producing a silver halide emulsion according to claim 1, wherein the amino group of the gelatin into which at least two or more OOH groups have been introduced is modified using pyromellitic anhydride. 4. The modification rate of an amino group in a gelatin molecule is as follows:
4. The method for producing a silver halide emulsion according to claim 1, wherein the content is 50% or more. 5. The silver halide according to claim 1, wherein said dispersion medium contains at least one polymer having a repeating unit represented by the following general formula (1). A method for producing tabular grains. Formula (1)-(RO) _n -wherein R represents an alkylene group having 2 to 10 carbon atoms.
n represents the average number of repeating units, and represents 4 or more and 200 or less. 6. The polymer having a repeating unit represented by the general formula (1) is a vinyl polymer containing at least one kind of a monomer represented by the following general formula (2) or a vinyl polymer represented by the following general formula (3): 6. The method for producing silver halide grains according to claim 5, wherein the polymer is at least one polymer selected from polyurethane. General formula (2) General formula (3) In the formula, R represents an alkylene group having 2 to 10 carbon atoms. n represents the average value of the repeating unit and represents 4 or more and 200 or less. R ¹ represents a hydrogen atom or a lower alkyl group;
² represents a monovalent substituent. L represents a divalent linking group. R
³ and R ⁴ are an alkylene group having 1 to 20 carbon atoms, a phenylene group having 6 to 20 carbon atoms, or a C 7 to 2 carbon atom.
Represents an aralkylene group of 0. x, y, z represent the weight percentage of each component, x is 1 to 70, y is 1 to 70,
z represents 20 to 70. Here, x + y + z = 10
0. 7. A polymer having a repeating unit represented by the general formula (1) has a block polymer component of a polyalkylene oxide represented by the following general formulas (4) and (5). A method for producing a silver halide tabular grain according to claim 5. General formula (4) General formula (5) In the formula, R ⁵ is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms,
Represents an aryl group having 6 to 10 carbon atoms, and n is 1 to 10
Represents an integer. Here, when n = 1, R ⁵ does not become a hydrogen atom. R ⁶ represents a hydrogen atom or a lower alkyl group having 4 or less carbon atoms and substituted by a hydrophilic group. x,
y represents the number of repetitions of each unit (number average degree of polymerization).