JPH07311428A - Production of silver halide particle - Google Patents

Abstract

PURPOSE:To obtain silver halide particles excellent in sensitivity and graininess by decreasing the complex forming ability with Ag<+> per unit weight of the dispersion medium by a specified rate or higher under same conditions in the period from after a specified time of the initiation of formation of nuclei to before a specified time of completion of growth of particles. CONSTITUTION:The silver halide is produced by adding silver ion and halogen ion to a dispersion medium soln. containing a dispersion medium and water. In the period from 10sec after the initiation of formation of nuclei to 5 min. before completion of growth of particles, the ability to form complex with Ag<+> is decreased by >=10% per unit weight of the dispersion medium under same conditions. As for the dispersion medium, natural material such as polysaccharide, algae, vegetable viscous material, animal protein, fermented viscous material can be used. Or, half-synthesized natural material such as polysaccharide deriv., cellulose and cellulose deriv., or synthesized polymer such as polyalkylene oxide, and polyvinyl deriv. can be used. Further, such a dispersion medium comprising polyvinylimidazole with substitution of a fog preventing agent for imidazole groups may be used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing silver halide (hereinafter referred to as "AgX") grains useful in the field of photography, and particularly to a method for producing AgX grains excellent in sensitivity and graininess. It is a thing.

[0002]

Conventionally, the dispersion (referred to hereinafter as "Ag ^+") silver ion medium in the aqueous solution and halide ions (hereinafter ^- the referred "X") that contains a dispersion medium and water producing AgX grains by adding In the method, the complex forming ability with Ag ⁺ per unit weight of the dispersion medium under the same conditions is reduced by 10% or more from the start to the end of the production.
The method for producing X particles is not known. Further, there is no description about improving the sensitivity and graininess of AgX particles by this method. When the AgX particles are formed, a sulfur-containing AgX solvent is used to accelerate the growth of the AgX particles, and when the AgX solvent becomes unnecessary, an oxidizing agent is added to reduce or deactivate the action of the AgX solvent. It is described in Japanese Utility Model Publication No. 61-3134. The oxidizing agent is added to reduce or deactivate the action of the AgX solvent, and is not intended to reduce the complex forming ability of the dispersion medium and Ag ⁺ by 10% or more under the same conditions. Absent. Further, the deactivation is mainly performed after grain growth, but the treatment of the present invention is mainly performed before grain growth.

Japanese Patent Laid-Open No. 61-3136 describes that in the precipitation step to the chemical ripening step, an oxidizing agent is added by the end of the chemical ripening step. JP-A-47-18
No. 35 describes that fogging is suppressed and stabilized by using red blood salt in the precipitation step or the physical ripening step. East German Patent 7376, JP-A-2-105139
JP-A-0348934A2 describes the presence of thiosulphonic acid during grain formation and during chemical ripening. However, these are intended to reduce the fog concentration during grain formation and chemical ripening, and are not intended to reduce the complex-forming ability of the dispersion medium by 10% or more. In particular, it is not intended to carry out the reduction treatment after the nucleation of tabular grains to immediately before the growth.

[0004]

The object of the present invention is to provide sensitivity,
The present invention provides a method for producing AgX particles having excellent granularity.

[0005]

The objects of the present invention have been achieved by the following items. (1) In a method for producing silver halide grains by adding silver ions and halogen ions to a dispersion medium solution containing at least a dispersion medium and water, from 10 seconds after the start of nucleation to 5 minutes before the end of grain growth. During the same period, the method for producing silver halide grains characterized by decreasing the ability to form a complex with Ag ⁺ per unit weight of the dispersion medium by 10% or more under the same conditions (2) The aspect is a tabular grain having an aspect ratio (diameter / thickness of grain) ≧ 1.8, and the method for producing silver halide grains described in (1) above. (3) The method for producing silver halide grains as described in (2) above, wherein 25% or more of the reduction is carried out after the nucleation of the tabular grains and before the growth. (4) The reduction of the silver halide grains according to (1) or (3) above, which is characterized by adding an oxidizing agent to the dispersion medium solution and oxidizing the dispersion medium. Production method. (5) The above, wherein the dispersion medium is gelatin
(1) A method for producing silver halide grains as described above.

Other preferred embodiments of the present invention are as follows. (6) The oxidation reaction is 0.1 hour or more, the temperature is 55 ° C. or less, p
The method for producing silver halide grains according to (4) above, which is carried out at H7 or less. (7) The method for producing silver halide grains according to (4) or (6) above, wherein 30% or more of the unreacted residual oxidizing agent is removed before the growth. (8) 50% or more of the reduction is performed after the nucleation of silver halide grains and before the growth thereof (1).
(6) The method for producing silver halide grains according to any one of the above. (9) 0.2 of the total amount of silver added during the growth of the silver halide grains
The method for producing silver halide grains as described in any one of (1) to (7) above, wherein the doubling is performed by adding silver halide fine grains described below. (a) A halogen characterized in that after forming fine particles having a particle diameter of 0.15 μm or less in a dispersion medium solution, the ability to form a complex with Ag ⁺ per unit weight of the dispersion medium is reduced by 10% or more. Silver halide fine particles. (10) The tabular grains are tabular grains having a {100} plane as a main plane and an aspect ratio (projection grain diameter / thickness) of 2 or more and a thickness of 0.5 μm or less. )-(9) The method for producing silver halide grains according to any one of the above. (11) The silver halide according to the above (5), wherein the dispersion medium is gelatin, and the content of methionine group in gelatin decreases by 10% or more as the complex-forming ability decreases. Method for producing particles.

The present invention will be described in more detail below. A. Dispersion medium. The dispersion medium referred to in the present invention does not include the AgX solvent described in JP-A-61-3134. Specifically, polysaccharides such as starch as a natural product (for example, corn, potato, wheat,
Rice, citrus, tapioca starch), seaweed (eg, fungi, agar, sodium alginate), plant mucilage (gum arabic, tragacanth, trolloaoi, konjac), animal protein (eg, glue, casein, gelatin, silk protein, egg white) , Plasma proteins), fermented mucilages (eg pullulan, dextran, levan), polysaccharide derivatives as semi-synthetic natural products, eg starches (eg soluble starch, carboxyl starch, British gum, dialdehyde starch, dextrin, cationic starch). , Cellulose and cellulose derivatives (for example, viscose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, cellulose sulfates) as a synthetic polymer, polyalkylene. Kishido (polyethylene oxide, polypropylene oxide and a polymer containing one or more of them in the main chain or side chain, polyethylene glycol, polypropylene glycol),

Polyvinyl derivatives (eg polyvinyl alcohol, polyvinyl amine, polyvinyl imidazole,
Polyvinylpyrazole, polyvinylpyrrolidone, polyvinyl ether, thioether synthetic polymer), polyacryl derivatives (for example, polyacrylamide, polyacrylic acid and its salts, polymethacrylic acid, polyacrylamidephenol, polysulfoalkylacrylamide),
Polystyryl derivatives (for example, polystyrylamine, halogenated polystyrene), others (water-soluble alkyd, polymaleic acid copolymer, polyethyleneimine, and the above-mentioned two or more copolymer compounds), inorganic polymers (for example, sodium polyphosphate, water glass) ) And a combination of two or more thereof.

In addition, the imidazole group of polyvinyl imidazole, the thioether group of thioether synthetic polymer, the dispersion medium in which the imidazole group of the quaternary polymer is replaced with a photographic antifoggant, and copolymers of two or more kinds thereof are mentioned. You can Preferred are gelatin, polyalkylene oxide, thioether synthetic polymer, and quaternary polymer containing imidazole group by Yano et al., And more preferred is gelatin. The molecular weight of the dispersion medium is 1000 or more, preferably 3000 to 1,000,000, and more preferably 5000 to 300,000. The water-soluble dispersion medium has a solubility in water of 0.2 g / 100 ml or more, preferably 1 g / 100 ml or more, more preferably 10 g / 10.
Refers to 0 ml or more of dispersion medium. The concentration of the dispersion medium in the dispersion medium solution is preferably 15% by weight or less, more preferably 0.1 to 10% by weight, still more preferably 0.5 to 5% by weight.

[0010] Gelatin is a kind of derivative protein that irreversibly converts collagen, which is a hard protein that forms connective tissue of animals, into water-soluble. Alkali-treated gelatin,
There is acid-treated gelatin. In addition, empty gelatin with cations and anions removed from gelatin, with a molecular weight of 10
00 or more, preferably 3000 to 300,000, more preferably 5000 to 150,000 gelatin and a methionine content of 1 to
100 μmol / g, preferably 3 to 60 μmol / g of oxidized gelatin, modified gelatin (gelatin in which the amino group at the terminal group is acylated or arboxyl group in the terminal group is carbonylated), alkylated gelatin in which the methionine group is alkylated, Gelatin in which 0 to 100% of arginine groups were ornithinated, pendant gelatin in which a photographically effective compound was organically bonded to a side chain group of gelatin, amidated gelatin, and a reducing agent such as SO ₂ were mixed in advance. Examples thereof include reducing gelatin and fractionated gelatin having a controlled molecular weight distribution. The source of gelatin is not particularly limited, and connective tissues of all animals can be used. Usually, bovine, porcine, fish bones and skins are frequently used, and bovine bones are most frequently used.

For details of these dispersion media, see the following references and Research Disclosure, Volume 307, Item 3.
07105, November, 1989, Tadanori Misawa, water-soluble polymer, Chemical Industry Co., Ltd. (1987), Society of Polymer Science, New Polymer Materials, One Point 24, Kyoritsu Shuppan (1990), Shinji Nagatomo, water soluble And Markets of Functional Polymers, CMC (1984), Ward et al., The Science and Technology
The description of of Gelatin, Academic Press, London (1964) can be referred to. See Hollister et al., Journal of Imaging Sci for thioether synthetic polymers.
ence, Vol. 31, 148-156 (1987), regarding the quaternary polymer, Japanese Examined Patent Publication No. 52-1636.
Regarding the description of No. 5, regarding gelatin, JP-A-5-265
113, 4-237039, 4-110934
No. 3, No. 2-253839, No. 3-241337, No. 3-171132, No. 2-301742, and No. 3-2.
No. 3437, No. 2-305876, No. 2-11194
No. 1, JP-A Nos. 62-163046 and 63-1192.
The description in No. 8 and World Patent 91-20014 can also be referred to.

The pH of the dispersion medium solution is preferably 1 to 1
2, more preferably 2 to 10, ^and the concentration of X ⁻ is preferably 10 ⁻⁵ to 10 ^−0.5 mol / liter, more preferably 10 −.
^-4 to 10 ^-1 mol / liter, and the most preferable combination can be selected and used. The dispersion medium solution before the start of production of AgX emulsion grains contains a dispersion medium which forms a complex with Ag ⁺ . From the start to the end of the production, the ability to form a complex with Ag ⁺ per unit weight of the dispersion medium under the same conditions is 10% or more, preferably 30 to 99%, more preferably 60 to 9%.
9%, more preferably 80-97%. Here, the same conditions mean that the temperature, pH, silver potential measuring device, container, stirring conditions and outside air conditions of the dispersion medium solution are the same. The complex-forming ability can be determined by the following method. Put Ag ⁺ selective electrode in the dispersion medium solution, while measuring the potential difference from the reference electrode (= silver potential), add AgNO ₃ solution into the dispersion medium solution, silver potential VS. AgNO ₃ addition amount, Seek a relationship. Next, under the other conditions (temperature, pH, atmosphere, etc.), prepare a solution containing no dispersion medium, and set the silver potential V
Calculate the relationship between S. AgNO ₃ addition amount.

The presence of the dispersion medium increases the amount of AgNO ₃ added required to reach the same silver potential, as compared with the case where the dispersion medium does not exist. The increased amount of Ag ⁺ is the Ag that forms a complex with the dispersion medium.
⁺ Equivalent to the amount. The amount of increase depends on the pH of the solution. The measurement pH is preferably 2 to 6, more preferably 2 to 4, and further preferably 2 to 3.5. At low pH, Ag ⁺
This is because the increase / decrease of the group strongly bonded to can be obtained. That is, low p
When measured by H, it is preferable that the ability to form a complex with Ag ⁺ is reduced by the specified amount. Measurement temperature is 25-60 ℃
Is preferable, and 30-50 degreeC is more preferable. After carrying out the lowering treatment, the dispersion medium solution is taken out, centrifuged, the supernatant is taken out, and the measurement may be carried out. It may be compared with a solution that has not been subjected to the treatment. The Ag ⁺ selective electrode can include a silver electrode, an AgBr electrode, an AgI electrode, and an Ag ₂ S electrode, and the reference electrode can include a sweet-smell electrode and a silver-silver chloride electrode. A preferable combination can be selected and used. The reduction can be performed at any time from 1 second after the start of nucleation to 5 minutes before the end of grain growth, but preferably 10 seconds after the start and 10 minutes before the end, more preferably Is performed from 30 seconds after the start to 20 minutes before the end. The following methods can be mentioned as the method of the reduction processing.

1) Add an oxidizing agent to oxidize the adsorption group.
The fact that the dispersion medium to form a Ag ⁺ complexed is to have a Ag ⁺ a coordination bond to a functional group is that having an electron pair donating group, is to have a Lewis base. An oxygen atom may be bonded to the electron pair to eliminate the coordination ability of the functional group. For example, in the case of the methionine group of gelatin, it means that the thioether group is changed to one or more of sulfoxide, sulfone and sulfonate. To oxidize a substance A ₁ is, more generally, to change a substance A ₁ to a substance having a standard oxidation potential higher than its standard oxidation potential. Here, the standard oxidation potential is V (volt) when the minimum energy required to excite one electron from the substance to a vacuum level is represented by eV. e is 1
It is the charge (coulomb) of each electron. The oxidation reduces the ability of the material to coordinate Ag ⁺ . For example, when acetaldehyde is oxidized to generate acetic acid, the oxidation potential of acetic acid is higher than that of acetaldehyde. On the other hand, substances that oxidize acetaldehyde undergo the opposite change. This is shown in FIG. 1 as a diagram. When compounds A ₁ and A ₂ having different standard oxidation potentials are reacted to obtain reaction products B ₁ and B ₂ , the potential relationship of these compounds is A ₁ <B ₁ , A ₂ > B _1. .

Specific examples of the oxidizing agent include O ₂ , O ₃ , compounds that easily release oxygen (eg, H ₂ O ₂ , organic thiosulfone compounds, AgO, Ag ₂ O, etc.), peroxides or the degree of oxidation. High oxides (eg MnO ₂ , PbO ₂ , NiO ₂ etc.), oxo acids (eg chloric acid, iodic acid, phosphoric acid, sulfuric acid, nitric acid, nitrous acid, permanganic acid, chromic acid, hypochlorous acid) and Its salts, peroxo acids (eg HNO ₄ , H ₃ PO ₅ , H ₄ P ₂ O ₈ , H ₂
SO ₅ , formic acid, peracetic acid, perbenzoic acid, etc.) and salts thereof, halogens (Cl ₂ , Br ₂ , I ₂ ), organic nitro compounds,
The metal salt having two or more kinds of electric valences and the metal having a higher valence number (for example, FeCl ₃ , CuCl ₂ etc.) can be mentioned, and these are added alone or in combination of two or more kinds. be able to. Of these, the oxidation reaction product is preferably an oxidizing agent that does not impair the photographic properties, H ₂ O ₂ , Na ₂ O ₂ ,
Hypochlorous acid, chlorous acid, PbO ₂ , peroxoacetic acid and O ₃ are preferable, and H ₂ O ₂ and peroxoacetic acid are more preferable. An oxidizing agent having a higher standard oxidation potential has a stronger oxidizing power, and the oxidizing treatment can be completed more quickly. Other,
By placing an inert electrode in the AgX emulsion and selecting the potential with respect to the reference electrode, the AgX emulsion can be oxidized to achieve the above purpose. A ground electrode or the reference electrode can be used as the standard electrode. Any known electrode can be used as the inactive electrode, but a platinum electrode or a Nesa glass electrode can be preferably used. It is preferable because mixing of impurities can be avoided.

The amount of the oxidizing agent added at this time is an amount necessary to achieve the above-mentioned object, and it varies depending on the type of the oxidizing agent used, the concentration of the dispersion medium, the oxidation reaction temperature and the time. It is possible to carry out experiments with various addition amounts in a small amount experiment and obtain the optimum addition amount by the trial and error method to use. Usually 10
^-6 to 1 mol / l, preferably ^10-5 to 10 ^-1 mol / l is used. The treatment time with the oxidizing agent is usually 1 minute or more, preferably 0.1 to 100 hours, more preferably 0.3 to 20 hours, and further preferably 0.6.
~ 20 hours. When the reaction requires a long time, it is preferable that the AgX emulsion is once transferred to another container and kept at a constant temperature. After the reaction of the desired amount is completed, the AgX emulsion may be returned to the reaction vessel and proceed to the next step. Temperature is 55 ℃
The following is preferable, and 5 to 45 ° C is more preferable. After adding the oxidant, it is more preferable to store the mixture in a static state without stirring and mixing. This is to avoid the influence of air mixing. The pH of the solution is preferably 8 or less, more preferably 2 to 7, and 2 to
6 is more preferable. This is because the oxidizing agent exerts a strong oxidizing power, and the dispersion medium can be rapidly changed as desired.

H ₂ O ₂ is H ₂ O ₂ + 2H ⁺ + 2C in a low pH aqueous solution.
l = 2H ₂ O or H ₂ O ₂ + H ⁺ + Cl = OH + H ₂ O (standard electrode potential E ⁰ of the reaction is 1,776 V, 0.71 V, Cl
Represents an electron) and has a strong oxidizing power. The relationship between the oxidation potential E and pH is represented by E = E ⁰ -0.059 pH. The equilibrium constant K ₁ of the reaction is given by ΔG ⁰ = RTlnK ₁ where ΔG ⁰ is the change in Gibbs free energy of the reaction. On the other hand, when a Z equivalent of a compound having a standard electrode potential difference of ΔE is reacted, there is a relation of ΔG ⁰ = −ZFΔE.
Therefore, the driving force ΔG ⁰ of the redox reaction and the reaction equilibrium constant K thereof can be obtained if ΔE is known. Where F is
Refers to the Faraday constant (96500 coulomb). If the oxidizing agent remains at the end of the treatment, the reducing agent may be added to further invalidate some or all of the residual oxidizing agent. The most preferable amount can be selected and used by the Anderson method.

In addition, metal colloids such as Pt and Pd, MnO ₂ ,
It is also possible to remove the residual H ₂ O ₂ using a metal oxide such as CO ₂ O ₃ . For example, these are dispersed in a gelatin dispersion medium, a hardener is added thereto, and the hardener is dried on the support. This is put into an emulsion and H ₂ O ₂ is decomposed into H ₂ O and O ₂ .
When the decomposition is completed, the coated product may be pulled up. It is preferable to remove 30 to 100%, preferably 60 to 100%, and more preferably 80 to 100% of the residual oxidizing agent by these methods. In addition, the next step can be performed while the unreacted oxidizing agent remains. The concentration of the remaining oxidant was measured by inserting a platinum electrode (platinum electrode potential V
S. Saturated calomel electrode) or by adding a photographic spectral sensitizing dye and measuring the degree of bleaching by spectral absorption. That is, it can be obtained by comparing standard calibration curves.

The following method can be given as another method. 2) The grain formation is stopped halfway, the AgX emulsion is centrifuged, a part or all of the supernatant is removed, and a dispersion medium solution having a smaller complex forming ability is newly added. 3) While forming particles or stopping particle formation on the way, a part or all of the dispersion medium solution is removed by ultrafiltration using an ultrafiltration membrane, and a dispersion having a smaller complex-forming ability is newly obtained. Add the media solution. As the filtration membrane, a membrane that does not pass AgX particles is used. In this case, as the newly added dispersion medium, a dispersion medium other than gelatin can also be preferably used. Regarding the dispersion medium, the above description can be referred to. As gelatin, modified gelatin such as phthalated gelatin (the amidation ratio is preferably 30 to 100%, 60 to 100)
% Is more preferable), and the methionine content is 0 to 80 μmol.
/ G gelatin and gelatin collected from silk can be more preferably used. The strong adsorption of gelatin having methionine groups on AgX particles is due to the concerted effect with other adsorption groups. Letting ΔH _{1 be} the change in enthalpy of adsorption due to total methionine in one molecule and ΔH ₂ be the change in adsorption enthalpy due to all other adsorbing groups, the activation energy for desorption of one molecule of gelatin is (ΔH ₁ + ΔH ₂ ). Therefore, for example, due to phthalation of gelatin, ΔH ₂
When becomes smaller, the methionine group alone cannot maintain the adsorption. In this case, 10% or more, preferably 30 to 99%, of the dispersion medium existing at the start of particle formation,
More preferably 60 to 99%, and even more preferably 80 to 9
It is preferred to remove 7%.

Specific examples of the reducing agent include hydrogen, relatively unstable hydrogen compounds (eg sodium borohydride, lithium aluminum hydride), lower oxides or salts of lower oxyacids (eg CO, SO _2). , Sulfites), electropositive metals (eg, alkali metals, Mg, Ca, Al, Zn, or their amalgams), salts of low-valent metals [eg, Fe (II), Sn ( II), Ti (III), (Cr (II)], low-oxidation organic compounds (eg, aldehydes, sugars, formic acid,
Oxalic acid). Of these, a reducing agent whose reduction reaction product does not impair the photographic properties is preferable,
Lower oxides or salts of lower oxygen acids are preferable, and sulfites and SO ₂ are more preferable. Other details of these oxidizing agents and reducing agents are edited by the Chemical Society of Japan, Volume 15, New Experimental Chemistry, Oxidation and Reduction, Maruzen (1976), Minoru Imoto, Organic Reaction Mechanism, Volume 10, Tokyo Kagaku Dojin. (1965),
Ogata Yoshiro, Oxidation and Reduction of Organic Compounds, Nankodo (196
3 years), JP-A-61-3134, Chemical Dictionary, "Oxidizing agent", "Reducing agent", and Kyoritsu Shuppan (1963).

To what extent and how the methionine group of gelatin is oxidized can be confirmed by the following method. Gelatin is completely decomposed into amino acids by an alkaline hydrolysis method (treated under a vacuum seal in the presence of 3.75 N NaOH at 110 ° C. for 16 hours), and then the same amount of HCl is added to neutralize. Using an amino acid analyzer utilizing the ninhydrin color development method, the peak intensities at the standard colorimetric peak positions of glycine, methionine, methionine sulfoxide, and methionine sulfone are compared. Calculate their cardinality ratio to the number of glycines. In the ordinary HCl acid decomposition method, [-S (O)-] → [-S-] is obtained under complete degassing conditions, and [-S-] → [-S (O)-] is obtained under incomplete degassing conditions. Therefore, the numbers of methionine, methionine sulfoxide, and methionine sulfone groups cannot be independently determined.

B. AgX particles. There is no particular limitation on the AgX particles that can be produced by the method of the present invention, and it can be used for the production of all conventionally known AgX particles. So-called normal crystal grains (cubes, octahedra, 14
In addition to the tetrahedron, it can be a dodecahedron, a tetrahedron, or a 48-sided grain that may or may not include twin planes or screw dislocations), and the main plane is the {111} plane and the aspect ratio (diameter / thickness) Is a tabular grain having a value of 1.5 or more [hereinafter referred to as "(111) tabular grain"], a tabular grain having a major plane of {100} plane and an aspect ratio of 1.5 or more [hereinafter "(100) tabular grain" In addition, special shaped particles and particles having rounded corners can be mentioned. For details, see the following references and JP-A-4-52636 and JP-A-4-123042.
1-101541, 5-103341, 2-
No. 32, No. 2-838, No. 4-56840, No. 3-
No. 135548, JP-A-63-271335, US Pat. Nos. 4,927,745, 4,916,052, 5,275,930, 5,264,337, and references cited therein. The description can be referred to.

Here, the diameter refers to the diameter of a circle having an area equal to the imaged area of the grain, and the thickness refers to the distance between two parallel principal planes of tabular grains. The diameter of these particles is preferably 0.1 μm or more, more preferably 0.2 to 10 μm. The coefficient of variation (standard deviation / average diameter) of the particle size distribution of the particles is preferably 0.4 or less, and 0 to 0.
3 is more preferable and 0 to 0.1 is more preferable. Among these grains, it can be more preferably used for the production of the tabular grains. The aspect ratio of the tabular grains is preferably 2 or more, more preferably 2 to 25, most preferably 4 to 16. The tabular grains preferably have a thickness of 0.5 μm or less, more preferably 0.05 to 0.3 μm,
˜0.2 μm is more preferred. The variation coefficient of the thickness distribution of the particles is preferably 0.4 or less, more preferably 0 to 0.3, further preferably 0 to 0.1.

The tabular grains preferably account for 60% or more of the total projected area of all AgX grains, more preferably 80 to 100.
%, More preferably 95 to 100%, and can be preferably used for producing an AgX emulsion. In the case of (111) tabular grains, the maximum side ratio [(side length of maximum side / side length of minimum side) of sides forming a main plane in one tabular grain] is 1 to 3, preferably 1 to 2 Hexagonal tabular grains and triangular tabular grains having a size larger than 3 can be mentioned. An AgX emulsion in which the hexagonal tabular grains account for 60% or more, preferably 80% or more, and more preferably 95 to 100% of the total projected area of all AgX grains is more preferable. Further, tabular grains having two twin planes parallel to each other are 60% or more, preferably 80% or more, more preferably 95 to 10% of the total projected area of all AgX grains.
The AgX emulsion accounting for 0% is more preferable.

In the case of (100) tabular grains, the following six can be listed when classified by shape. 1) The shape of the main plane is a right-angled parallelogram, and the particle (length of long side / length of short side) is 1 to 10, preferably 1 to 3 in one tabular grain, 2) the right-angled parallel Of the four corners of the quadrilateral, 1
Particles lacking one or more, preferably 1 to 3, non-equivalently. That is, [(maximum missing area / minimum missing area)
= Particles in which a ₁ is 2 to ∞], 3) particles in which the four corners are equivalently missing (particles in which a ₁ is smaller than 2), 4) 5 to 100% of the area of the missing portion, preferably 20-100% is (111)
A particle that is a surface, 5) a particle in which at least two opposing sides of the four sides that form the main plane are curved curves that are convex outward,
6) Particles in which one or more, preferably 1 to 3 of the four corners of the right parallelogram are missing in the right parallelogram as shown in FIG. Other details of these tabular grains are described in JP-A-5-281640 and JP-A-5-313273,
US Pat. Nos. 4,386,156 and 5,264,33
7, No. 5,275,930, European Patent No. 05343.
95A1, Japanese Patent Application No. 4-214109, 5-1176.
No. 24, No. 5-96250, No. 5-264059,
The descriptions in JP-A-5-248218 and JP-A-6-47991 can be referred to.

When tabular grains are produced, the
It is manufactured during the process of aging → aging → growth. In this case, after nucleation
It is better to carry out the reduction treatment between
preferable. That is, 25-100% of the decrease during the period,
Preferably 50 to 100%, more preferably 90 to 10%
It is preferable to complete 0%. The reason is
Ri. In the case of tabular grain nucleation, control the defect species generated
There is a need to. In this case, the amount of strong adsorption on AgX particles
The dispersion medium prevents various defects from entering. Therefore various
Prevent the introduction of defects and introduce only certain defect types
When you want to have many functional groups that strongly adsorb to AgX particles
Nucleation is preferably performed using a dispersion medium. On the other hand,
To form tabular grains with uniform spectral ratios
Is the number of functional groups that grow strongly on the edge of the particle.
It is preferable to carry out under a small amount of dispersion medium. The reason is
When the adsorption group of the dispersion medium is strongly adsorbed on the edge part, the edge part of the edge part
The growth rate becomes the desorption rate of the adsorption group, and the edge selection
This is because growth is suppressed. On the other hand, the tabular grain edge
In order to selectively grow only the j
It is preferably grown. It has no crystal at the edge
Due to the existence of the pits, new growth is achieved even under low supersaturation.
Long nucleation may occur, but crystal defects exist on the main plane.
Therefore, new growth nuclei are formed under low supersaturation.
Because it is hard to get rid of. When grown under high supersaturation (
Growth rate of main surface / growth rate of main surface) = x ₁Is reduced
It

However, when grown under a low supersaturation degree, the frequency of growth nuclei formation decreases, and a mononuclear growth mechanism is generated.
1) In tabular grains, the diameter distribution becomes wider with growth. Here, the mononuclear growth mechanism refers to a mode in which, when one growth nucleus is formed somewhere on the surface, the nucleus grows and the next mononuclear is not formed until one atomic layer surface is completed. That is, the growth nucleus formation process is a growth rate-determining process (average time interval for formation of growth nuclei >> average time required to complete one surface) = a ₁ . In the (111) tabular grain, the trough on the edge surface is the growth active point, and the number of the active points on one grain is proportional to the trough length of the edge of the grain. When the particles are grown by the mononuclear growth mechanism, the edge growth rate (dL ₁ / dt)
Is proportional to the trough line length (L ₁ ). Therefore, large particles grow faster than small particles, and the particle diameter distribution becomes wider. In such a case, in order to prevent this, an adsorbent that adsorbs with an appropriate adsorption force can be present on the particle surface, preferably at the edge portion. The adsorbing power of the adsorbent is preferably 1 to 80% of the adsorbing power of the methionine group in gelatin, and 3 to 6
0% is more preferable, and 5-40% is further preferable. The adsorption power can be compared by the amount of heat generated when adsorbed (ΔHcal / mol).

Specific examples of the adsorptive group include ethylene oxide group, propylene oxide group, imidazole group, pentose group, hexose group, hexosamine group, nucleic acid bases (adenine, guanine, thymine, cytosine, lauryl), purine base, Examples thereof include pyrimidine bases, antifoggants, and sensitizing dyes, with ethylene oxide groups, propylene oxide groups, and imidazole groups being preferred. An adsorbent having one or more of these groups is preferred, and one or more, preferably 5 or more, such groups are contained in one molecule.
Adsorbents having up to 10 ⁴ can be used. The molecular weight of the adsorbent is 100 or more, preferably 200 to 300,000. The addition amount is preferably 10 ^{-2 to} 50 g / liter,
It is more preferably 0.05 to 10 g / liter. In the case of (111) tabular grains having a Br ⁻ content of 50 to 100 mol%, a polyalkylene oxide compound is preferable, and the details thereof are described in European Patent No. 0514742A1 and Japanese Patent Application No. 5-1184.
No. 18, No. 5-191814, and No. 5-263128 can be referred to. Especially Japanese Patent Application 5-19
The aspects described in Nos. 1814 and 5-263128 can be preferably used. That is, a) at least one kind of a polymer having a repeating unit represented by the following general formula (1) and at least one kind of a polymer having a repeating unit represented by the following general formula (2) A mode in which the tabular grains are formed in a reaction solution that is present at a concentration. (1)-(RO) _n- , (2)-(CH ₂ CH ₂ O) _m- , and R represents an alkylene group having 3 to 10 carbon atoms. n,
m represents the average number of each repeating unit and is a value of 4 to 500, preferably 4 to 200, respectively. b) A mode in which the tabular grains are formed in a reaction solution in which at least one kind of polymer having a repeating unit of a monomer represented by the following formula (3) is present in the above concentration. Here, R ¹ represents H or a lower alkyl group, and R ² represents a monovalent substituent. R ³ represents an alkylene group having 3 to 10 carbon atoms, and L represents a divalent linking group. p represents the average number of repeating units and is a value of 4 to 500, preferably 4 to 200. c) 1: 100 to 10 of at least two kinds of the monomer represented by the general formula (3) and the monomer represented by the general formula (4).
A mode in which the tabular grains are formed in a reaction solution in which a copolymer having a molecular number ratio of 0: 1, preferably 5: 100 to 100: 5 is present at the above concentration. Here, R ⁴ represents H or a lower alkyl group, R ⁵ represents a monovalent substituent, and L represents a divalent linking group. q represents the average number of repeating units and is a value of 4 to 500.

[0029]

[Chemical 1]

The polyalkylene oxide compound can be added before nucleation to 5 minutes before the end of growth, but it is preferable to add it after nucleation and immediately before the start of growth. The pH of the reaction solution is 1.5 to 10, preferably 2
It is possible to select and use a preferable value of ˜8. For other details of the polyalkylene oxide compound, the descriptions in Japanese Patent Application Nos. 5-191814 and 5-263128 can be referred to. In the case of (100) tabular grains, the above quaternary polymer can be preferably used.

When the adsorbent is preferentially adsorbed on the edge portion of the tabular grain, the growth rate of the edge surface with respect to the main plane is reduced, and the produced grain has a low aspect ratio. Since the adsorbent is uniformly adsorbed on the entire surface (area of the main plane> area of the edge surface), growth of the main surface is suppressed more than growth of the edge surface. It is a new one on the particle surface
This is because the number of adsorbent molecules adsorbed when the atomic layer surface is completed is proportional to the area of the surface. That is, when the supply rate of solute ions is constant, the time required to complete one atomic layer surface is proportional to (average adsorption residence time of adsorbent × area of the surface). When the growth rate of the edge surface is decreased in this manner, the relationship of a ₁ above does not hold,
It is not a mononuclear growth mechanism. In this case, the growth rate of particles in the diameter direction is represented by (mononucleus formation rate × average growth rate of mononuclear particles in two-dimensional direction × thickness of one atomic layer / area of edge surface). Where mononuclear formation rate ∝ trough length.

When the thickness of the tabular grains is the same and the average growth rate of the growth nuclei in the two-dimensional direction is the same, the large grain and the small grain have the same (trough length / edge surface area) and the large grain Both the small particles and the small particles have the same diameter growth rate, and the coefficient of variation of the diameter distribution (diameter distribution / average diameter) becomes smaller as the particles grow. When many strong adsorption groups are present, particles can hardly grow. When the abundance is reduced, the adsorption is a random distribution, the desorption is a random phenomenon, and the average adsorption residence time is long, so that the growth rate of the growth nuclei in the two-dimensional direction varies between particles. Large variations. Therefore, the above relationship does not hold and the size distribution spreads. For particles with very strong adsorption groups adsorbed to the edge,
Almost no growth occurs in the edge direction, resulting in small-diameter thick plate particles. In a mode in which a large number of weakly adsorbing groups are adsorbed per particle, the variation between the particles becomes smaller as the number of adsorbing groups increases, which is preferable.

In a mode in which only a ₂ particles are randomly adsorbed per particle, the coefficient of variation CV of the variation in the number of adsorbed particles is CVOC (1 / a ₂ ) ^0.5 . Further, in the case of particles having the same shape in which adsorbing groups adsorbed only (a ₂ / particle), the variation in the time required to complete one atomic layer was such that desorption was a random phenomenon and the average adsorption residence time was b ₁ Assuming that, it is inversely proportional to b ₁ / a ₂ . Therefore, in the mode in which a large number of adsorption groups having a short b ₁ are adsorbed, the variation becomes small, which is preferable. The variation coefficient of the variation in the time required to complete one atomic plane with the particles of the same shape is preferably 0 to 40%, 0 to
20% is more preferable, and 0-10% is further preferable. That is, the size distribution is made uniform by changing the growth mode in which mononuclear formation on the edge surface is rate-determining to the growth mode in which the growth of growth nuclei in the two-dimensional direction is rate-limiting. Suppressing the growth rate of the growth nuclei means suppressing the edge growth rate, and x ₁ decreases. Therefore, the growth rate of the growth nuclei is suppressed within a range in which the decrease in x ₁ is allowable.

In the case of (100) tabular grains (the number of active growth points at the edge / the number of grains), since large grains = small grains, the variation in size distribution is ( 111) Smaller than that of tabular grains. Therefore, in this case, [the extent of decrease in the growth rate of the growth nuclei <the extent of decrease in the growth rate of (111) tabular grains] is sufficient. The ripening step is a step of eliminating non-tabular grains by Ostwald ripening, growing tabular grains, and increasing the projected area ratio of tabular grains. When the above treatment is carried out, the adsorbing groups strongly adsorbed to the edge portions of the tabular grains disappear, and the tabular grains grow smoothly in the edge direction. That is, the aging process is promoted. From this point, it is more preferable that the treatment is performed after the nucleation and before the start of ripening. However, the ripening process causes the tabular grains to grow under a low supersaturation degree, so that the size distribution tends to broaden. Therefore, it is possible to take the same measures as those for the growth. That is, it is preferable to allow the adsorbent having an appropriate adsorption power to be present.

In addition, the treatment can be performed after the aging and before the growth, or can be performed during the aging. (100)
In the case of tabular grains, in the ripening, the projected area ratio of the tabular grains is preferably increased to 60 to 100%, and
Aspects of 60% can be taken. In this case, the growth can be made to be a supersaturated growth, and the non-tabular grains can be eliminated while growing. Furthermore, it can be eliminated by further aging after growth. When the tabular grains are grown by the ionic solution addition method in the presence of non-tabular grains, there are the following advantages. Since the supersaturation degree of the solution is maintained at the solubility of the fine particles or more, the edges of tabular grains are dissolved and Ostwald ripening of the type of depositing on the main plane is prevented. Therefore, tabular grains having a higher aspect ratio can be obtained. In this case, if the supersaturation degree of the solution is too high, the fine particles grow and it becomes difficult to extinguish them later. Therefore, it is preferable to grow the superfine particles under a supersaturation degree at which they hardly grow. Specifically, the solubility of the fine particles present is preferably 0.7 to 1.2 times, more preferably 0.8 to 1.0 times, and 0.9 to 1.0 times.
Double is more preferable. In the case of the tabular grains, even when grown under the low supersaturation degree, since the size distribution of the growth is small, the growth method can be preferably used.

As described in Japanese Patent Application No. 5-96250, when the nuclei having a halogen composition gap surface in the central portion are aged to eliminate non-tabular grain nuclei, different halogen ions are added to the tabular grains during growth of the tabular grains. Accumulates. At this time, defects such as screw dislocations are further incorporated in the tabular grains, and growth promoting defects having a growth vector component in a direction perpendicular to the main plane are incorporated. Therefore, the tabular grains become thicker as they grow. In order to prevent this, different halogen ions may be diluted with host halogen ions. As a specific example, in the case where the (inner core | outer core) is the (AgX ₁ | AgX ₂ ) nucleus, Ag ⁺ and ⁺ are added to dilute the foreign ion X ₂ released during aging.
X ₁ ^- method of aging while adding, the structure of the nucleus (AgX ₁ |
AgX ₂ | AgX ₁ ), a method of adding fine particles having a particle diameter of 0.15 μm or less and a high x ₁ composition ratio, and a combination method of two or more thereof. The number of screw dislocation defects newly formed when the non-tabular grain nuclei are extinguished by the dilution is preferably 0 to 0.9, and more preferably 0 to 0.2, which is the number of existing defects.

The tabular grains can be formed by forming a lattice constant gap plane on the {100} plane during nucleation. One of the specific methods is to form a halogen composition gap surface. Another method is to form a gap surface of different ion doping amount. When the lattice constant gap plane is formed on the {111} plane, the lattice strain is relaxed by the formation of stacking faults, but there is no other relaxation mechanism on the {100} plane, which leads to the formation of screw dislocation defects. Conceivable. If a screw dislocation is formed on the {111} face and the face grows endlessly, a crystal phase of only Ag ⁺ or X ⁻ is formed, which is inconvenient. Also, in this aspect, X
^- be formed lattice constant gap with a salt composition change Ag ⁺
Since the layers are interposed, the strain is relaxed and screw dislocation defects are difficult to form. On the other hand, the {100} plane has no such inconvenience. In the case of (111) tabular grains, the projected area ratio of the tabular grains is preferably increased to 50% or more, more preferably 80 to 100% in the ripening process. The non-tabular grains remaining in the ripening process can be eliminated by the growth process and / or Ostwald ripening after the growth.

In the case of (111) tabular grains, the probability of twin plane formation during nucleation depends on supersaturation factors such as X ^- salt concentration, dispersion medium concentration, temperature and pH, and each factor has additivity. In order to form small-sized tabular grains, the probability of forming twin planes should be set as high as possible under the condition that the nucleation condition is low in AgX solubility, and the ratio of non-parallel multiple twin grains is within the allowable range. AgX low solubility conditions are low temperature, low X ^- salt concentration [(A
gX solubility vs. X ^- salt concentration) curve shows a low AgX solubility region, preferably 10 ^-1 to 10 ^-4 mol / liter, more preferably 10 ^-2 to 10 ^-4 mol / liter. ], Low pH (of amino group of dispersion medium, carboxyl group
The ability to form a complex with Ag ⁺ is reduced], and the concentration of gelatin is low (the concentration of a complex of gelatin and Ag ⁺ is low). When the X ^- salt concentration is lowered, the twin plane generation probability is lowered, which can be adjusted to an optimum value by lowering the dispersion medium concentration. The temperature is preferably 10 to 50 ° C, more preferably 15 to 40 ° C. Dispersion medium concentration is 0.0
1 to 5% by weight is preferable, and 0.05 to 1% by weight is more preferable. 1-8 are preferable and, as for pH, 2-6 are more preferable. A dispersion medium can be included in the added Ag ⁺ liquid and / or X ⁻ salt liquid. The concentration of the dispersion medium is preferably 0.3 to 3 times the concentration of the dispersion medium solution in the reaction vessel, 0.5 to
2 times is more preferable. As the dispersion medium, the above-mentioned dispersion medium can be used, low molecular weight gelatin having a molecular weight of 100,000 or less is more preferable, and the gelatin having 3000 to 50,000 is further preferable. The subsequent ripening process will increase the X ^- salt concentration to preferably 10 ^-2
It is preferable that the temperature be 10 ^-1 mol / liter, the temperature be raised to 10 ° C. or higher, more preferably 20 to 60 ° C., and the ripening is carried out under a low gelatin concentration. The gelatin concentration is 0.02
2% by weight is preferable, and 0.05 to 0.5% by weight is more preferable. 1-8 are preferable and, as for pH, 2-6 are more preferable. This is because the lower the gelatin concentration, the faster the ripening.

Cl ^- content is 30 mol% or more, preferably 5
In the case of nucleation of 0 to 100 mol% of particles in a gelatin dispersion medium solution, the probability that twin particle nuclei are formed depends largely on the pH of the solution. The probability increases as the pH increases and as the protective colloid property of the dispersion medium decreases.
Therefore, AgX of the above halogen composition with a low twin grain mixing ratio
When forming particles, the pH is preferably 5.5 or less,
A pH of 2 to 4.5 is more preferable. If the AgCl content is high,
Cl ^- for high ionic, high pH, gelatin -COO ^-
And Cl of the particle surface ^- greater charge repulsion between. Therefore, the protective colloid property of gelatin is lowered, and the probability is increased. In the low pH -COO ^- eliminates almost eliminates electrostatic repulsion most, protective colloid property due to the binding group such as methionine is increased. Twin-free grains having the halogen composition or (100)
The conditions can be preferably used as the nucleation conditions for tabular grains. The content: of 50~ ^- Br ionic is not greater
In the case of nucleation of 100 mol% particles, the opposite is true. This case can be explained by a decrease in the ability of gelatin to form a complex with Ag ⁺ due to a decrease in pH.

With respect to other details of the (111) tabular grain, it is possible to refer to the documents described below and the documents described below. For particles with high Cl ⁻ content, US Pat.
No. 176,992, No. 5,061,617, No. 4,4
00,463, 5,185,239, 5,18
No. 3,732, No. 5,178,998, No. 5,17
8,997, JP-A-4-283742, 4-16
1947, 3-288143, 3-21263.
No. 9, No. 3-116133, No. 2-301742,
2-34, JP-A-62-218959, 63-
No. 41845, No. 58-111936, No. 62-16.
No. 3046, No. 62-299961, No. 64-707
The description of No.41, Br ^- 63-151618 JP regard high particles content:, the 63-11928 Patent, JP-A-2-28638, the 1-131541 JP, the 2-83
No. 8, No. 2-34, No. 2-146033, No. 2-2
No. 98935, No. 3-121445, No. 4-3454.
No. 4, No. 5-173267, and Japanese Patent Application No. 5-118418.
You can refer to the description of the issue.

C. Ag⁺And X^-Supply method. Ag⁺And X^-The supply method is as follows: 1) Silver in which soluble silver salt is dissolved
Halogen salt solution in which salt solution and soluble halogen salt are dissolved
(Hereinafter "X^-Ionic solution addition to supply salt solution)
Method 2) Form an AgX fine grain emulsion in advance, and use the fine grain emulsion.
Supply method, 3) splash addition method, 4) both of the above
How to use can be given. Soluble silver salt, soluble ha
Solubility in water at room temperature is 1 wt% or less
Above all, it is preferable to add 10% by weight or more of salt.
Ed., Chemical Society of Japan, Handbook of Chemistry, Chapter 8, Maruzen (1993
Year) can be referred to. Usually AgNO
₃And Cl ^-, Br^-, I^-Alkali metal salt, Ammoniu
Mumu salt can be preferably used. As AgX particles
Is the diameter of the particle (a circle with an area equal to the projected area of the particle
The diameter) is preferably 0.15 μm or less, 0.01 to
0.1 μm is more preferable. Halogen composition is AgCl, AgB
r, AgI and mixed crystals of two or more of them can be mentioned.
It The size distribution is preferably a coefficient of variation of 0 to 0.4,
0 to 0.2 is more preferable.

The fine particles preferably have substantially no double or more twin planes, and more preferably do not substantially have single twin grains. Furthermore, it is preferable that the compound does not substantially have a screw dislocation defect. Here, the number of “not substantially having” is preferably 3% or less, more preferably 1% or less, and further preferably 0 to 0.1%. The fine particles can be added continuously or intermittently. The halogen composition of the fine particles can be continuously changed or intermittently changed. The most preferable combination of the fine grain emulsion having a pH of 1 to 12 and a pX of 0.5 to 6 can be selected. For details thereof, reference can be made to the descriptions in JP-A-4-34544, JP-A-1-183417 and the references cited therein.

Any conventionally known apparatus can be used as the apparatus for supplying Ag ⁺ and X ⁻ and the apparatus for forming particles. Addition holes are installed in the dispersion medium solution (number of addition holes / 1
It is preferable to use a porous addition system in which the addition liquid is 2 or more, preferably 4 to 10 ¹⁵ , and the addition holes are made of a rubber elastic film and the holes are opened at the time of addition and closed at the time of stopping the addition. I can do things. The details of these devices will be described later, and JP-A-3-21339 and JP-A-1-183.
No. 417, No. 4-193336, No. 4-330427.
No. 3-155555, 3-200952, 3-246534, 4-283741, 4-1.
84326-184330, 5-11377,
5-45757, 5-61134, 5-33
7350, 6-11779, US Pat. No. 5,25.
4,454, Japanese Patent Application Nos. 4-240283, 4-30
The description of No. 2605 and No. 5-25314 can be referred to.

When forming the fine particles, a dispersion medium that strongly adsorbs to the AgX particles enables the formation of the above-mentioned fine particles. On the other hand, when the fine particles are supplied to grow tabular grains, the bond between the dispersion medium and the AgX grains should be weak. This is because it promotes dissolution of the fine grains and growth of tabular grains. Therefore, after the AgX fine particles are formed in a dispersion medium solution, the treatment is performed, and the complex forming ability with Ag ⁺ per unit weight of the dispersion medium under the same conditions is 10% or more, preferably 30 to 99%. , More preferably 60-95%,
More preferably, it is preferable to reduce by 80 to 95%.

When the tabular grains are grown by Ostwald ripening with the addition of the fine grain emulsion, it is not preferable that the fine grains of the fine grains undergo the ripening and more fine grains appear. When the whole amount of the fine grain emulsion is added at once, the ripening is likely to occur. If added slowly, it takes a long time to grow and the size distribution of tabular grains broadens. Therefore, practically, it is possible to add at various addition rates and select and use the most preferable addition rate. Although it is preferable to grow tabular grains only by the method of adding fine particles, Ag ⁺
It is also possible to use the method of adding an ion solution of X ⁻ and X ⁻ together. It is also possible to carry out a part of the growth by an ionic solution addition method and the rest by a fine particle addition method. In those cases, the total added silver amount ratio in the fine particle addition method is 0 to 1.0, preferably 0.5 to 1.0, and more preferably 0.7 to 1.0.
Is.

The fine grain emulsion is preferably prepared and added in advance in another container, and more preferably added after being formed in a mixer provided near the reaction container. Other than the method of adding fine particles, a method of adding splash can be used. The addition rate of the seed crystal particles is 1.2 times or more, preferably 1.5 to 30 times the critical addition rate, and preferably 1 to 5 times.
Ag ⁺ salt solution and X ^- salt solution are added for 00 seconds, more preferably 1 to 100 seconds to generate new nuclei. Subsequent ripening of the new nucleus destroys part or all of it. Here, the critical addition rate refers to an addition rate at which new nuclei start to be generated when the solution is added at a higher addition rate. The longer the addition period, the higher the proportion of highly supersaturated growth of seed crystals, and the more tabular grains grow in the thickness direction. That is,
The advantages of the particulate addition growth method are impaired. In addition, the new nuclei that have grown grow larger, and their subsequent extinction is delayed. If it is too short, the generated new nucleus is too small and its solubility is too high, and it disappears immediately after the generation. That is, the ion addition method is approached, and the advantages of the fine particle addition method are impaired. Therefore, it is preferable to select the optimum addition rate and addition period for each system. The addition → aging is performed once or more, preferably 3 to
It can be performed 100 times.

D. Other. After the AgX particles are formed in this manner, the AgX particles are usually washed with water and chemically sensitized. Further, a photographically effective additive such as a spectral sensitizer and an antifoggant is added and coated on the support. In the state of being washed with water, the dispersion medium needs to be strongly bonded to the AgX particles to some extent or more. Regarding the order of addition of the chemical sensitizer, the spectral sensitizing dye and the antifoggant, an optimum order can be selected according to the purpose. When the dye is added, it is preferable that the variation in the adsorption coverage between particles is reduced and the particles are uniformly adsorbed. In this case, it is better to slow down the adsorption speed of the added dye to some extent. That is, the uniformity is enhanced when the adsorption proceeds after the added dye is mixed more uniformly. The activation energy required for the dye to adsorb to the AgX particles is the exchange adsorption energy with the adsorbed dispersion medium molecule. It is primarily the activation energy of desorption of the dispersant molecules.

Therefore, in order to further reduce the dye adsorption rate, a dispersion medium having a higher activation energy for desorption may be used and a solution containing the dye may be added to the AgX emulsion at a lower temperature. In this case, a dispersion medium can be newly added after the particles are formed and before the dye is added, or a new dispersion medium can be added after removing a part or all of the dispersion medium. This aspect can be expressed as follows. From the time after the grain formation until the addition of the spectral sensitizing dye, the adsorption energy per 1 g of the AgX grains is 1.1 times or more, preferably 1.5 to 30 times, the energy of the already existing dispersion medium. Preferably 2-3
Dispersion medium of 0 times 0.5g per liter of AgX emulsion
Or more, preferably 2 g or more, more preferably 6 to 100
Add only g. The dispersion medium preferably has a molecular weight of 1,000 or more, more preferably 3,000 to 300,000. The desorption energy is simply Ag that is obtained by removing the dispersion medium by centrifugation.
The dispersion medium solution is added to the X particles, the mixture is stirred, and the calorific value of the comparative sample (the calorific value when water is added to the AgX particles under the same conditions) is subtracted from the generated calorific value. The dispersion medium can be selected from the above-mentioned dispersion medium, and particularly, the methionine content is 30 μmol / g or more, preferably 40 to
300 μmol / g gelatin (having an ether group or alcohol group of sulfur, selenium, tellurium, and having a content of these groups of 30 μmol / g or more, preferably 40 to 1000 μm
Mol / g synthetic polymer) is more preferred. This aspect has the following other advantages. When the tabular grains adsorb the dye at a high coverage, the number of bonding points between the AgX grains and the dispersion medium usually decreases. As a result, AgX particles tend to aggregate, and AgX particles tend to settle. Further, the discrimination between the latent image and the fog nuclei at the time of development is reduced, and the fog density is increased. By adopting the above-mentioned aspect, these drawbacks are remedied.

The obtained particles may be used as host particles, and epitaxial particles may be formed on the edges and / or corners of the particles before use. Further, particles having dislocation lines inside may be formed using the particles as a core. In addition, by using the particles as a substrate and stacking an AgX layer having a halogen composition different from that of the substrate, particles having various known particle structures can be prepared. Regarding these, it is possible to refer to the description of the literature described later. Also,
Chemical sensitization nuclei are usually imparted to the obtained emulsion grains.

In this case, the location and the number of the chemically sensitized nuclei generated /
It is preferred that cm ² be controlled. Regarding this, JP-A-2-838, 2-146033 and 1-2.
No. 01651, No. 3-121445, JP-A-64-7
No. 4540, Japanese Patent Application Nos. 3-73266 and 3-1407.
No. 12 and No. 3-115872 can be referred to.

Further, a shallow inner latent emulsion may be formed and used by using the tabular grains as a core. It is also possible to form core / shell type particles. Regarding this, JP-A-59-
133542, 63-151618, U.S. Pat. Nos. 3,206,313, 3,317,322, 3,761,276, 4,269,927, 3,267,778. Can be referred to. The AgX emulsion grains produced by the method of the present invention can also be used as a blend with one or more other AgX emulsions.
The blending ratio can be appropriately selected and used in the range of 1.0 to 0.01.

There are no particular restrictions on the additives that can be added to these emulsions during the period from grain formation to the coating step, and any of the heretofore known photographic additives are preferably used, preferably 10 ^-8 to 10 ^-1 mol.
It can be added in an amount of / molAgX. For example, A
gX solvent, dopant for AgX particles (for example, Group 8 noble metal compounds, other metal compounds, chalcogen compounds, S
CN compound, etc.), dispersion medium, antifoggant, sensitizing dye (blue,
Green, red, infrared, panchromatic, ortho), supersensitizer,
Chemical sensitizers (sulfur, selenium, tellurium, gold and Group VIII noble metal compounds, phosphorus compounds, rhodan compounds, reduction sensitizers singly or in combination of two or more thereof), fogging agents, emulsion precipitants, surfactants Agents, hardeners, dyes, color image forming agents, color photographic additives, soluble silver salts, latent image stabilizers, developers (hydroquinone compounds, etc.), pressure desensitizing agents, matting agents, etc. it can.

The AgX emulsion grains of the present invention and the AgX emulsion produced by the production method can be used in all conventionally known photographic light-sensitive materials. For example, black-and-white silver halide photographic light-sensitive material [for example, X-ray sensitive material, printing sensitive material, photographic paper,
Negative film, Mike's film, direct positive sensitive material, ultrafine particle dry plate sensitive material (for LSI photomask, shadow mask, liquid crystal mask), color photographic light-sensitive material (eg negative film, printing paper, reversal film, direct positive color feeling) Materials, silver dye bleaching method photographs, etc.). Further, a diffusion transfer type photosensitive material (for example, a color diffusion transfer element,
Examples thereof include a silver salt diffusion transfer element), a photothermographic material (black and white, color), a high-density digital recording light-sensitive material, and a holographic light-sensitive material.

The coated silver amount can be selected to be a preferable value of 0.01 g / m ² or more. There is also a restriction on the constitution of the photographic light-sensitive material (for example, layer composition silver / color-forming material molar ratio, silver amount ratio between the layers, etc.), exposure, development processing and photographic light-sensitive material manufacturing equipment, and emulsion dispersion of photographic additives. However, any conventionally known modes and techniques can be used. Regarding the conventionally known photographic additives, photographic light-sensitive materials and their constitutions, exposure and development treatments, photographic light-sensitive material manufacturing apparatus, etc., the descriptions in the following documents can be referred to.

Research Disclosure
Disclosure), Volume 176 (Item 17643) (12
Mon, 1978), volume 307 (item 30710)
May, November, 1989) Duffin, Photographic Emulsion Chemistry, Focal
Press, New York (1966), by Bill (EJBir
r), Stabilization of photographic silver halide emulsions
of Photographic Silver Halide Emulsions), Focal Press, London (1974),
James (TH James), Theory of the Photographic Process (The Theo
ry of PhotographicProcess) 4th Edition, Macramin (Mac
millan), New York (1977)

P. Glafkides, Chemistry and Physics of Photography (Chimie et Physique Photographiques), No. 5.
Edition, Edition da Lysine Never (Edition de
I'Usine Nouvelle, Paris (1987) Second Edition, Paul Montel, Paris (1957), Zelikmann et al. (VL Zalikman at al.), Preparation and coating of photographic emulsions (Maki
ngand Coating Photographic Emulsion), Focal Press
(1964), KR Hollister Journal of Imaging Science (Journal of Im
aging science), Vol. 31, p. 148-156 (19
1987), Muskasky (JEMaskasky), volume 30,
p. 247-254 (1986), 32 volumes, 160
~ 177 (1988), 33 volumes, 10-13 (19)
1989)

Freezer et al., The Basics of Silver Halide Photographic Process (Die Grundlagen Der Photographischen Prozesse
Mit Silverhalogeniden), Akademische Verlaggesellschaf
t), Frankfurt (1968). JCIA Monthly Report 19
1984, December issue, p. 18-27, Journal of the Photographic Society of Japan,
Volume 49, 7-12 (1986), Volume 52, 144-
166 (1989), 52 volumes, 41-48 (198)
9), JP-A-58-113926 to 113928,
59-90841, 58-111936, 6
2-99751, 60-143331, 60-
143332, 61-14630, 62-62.
No. 51, No. 63-220238, No. 63-15161.
No. 8, No. 63-281149, No. 59-133542.
No. 59-45438, No. 62-269958,
63-305343, 59-142539, 62-253159, 62-266538, 6
No. 3-107813, No. 64-26839, No. 62-
No. 157024, No. 62-192036,

Japanese Unexamined Patent Publication Nos. 1-297649 and 2-127
No. 635, No. 1-158429, No. 2-42, No. 2
No. 24643, No. 1-146033, No. 2-838.
No. 2, No. 28286, No. 3-109539, No. 3
-175440, 3-121443, 2-73
No. 245, No. 3-119347, and U.S. Pat. No. 4,63.
6,461, 4,942,120, 4,26
9,927, 4,900,652, 4,97
5,354, European Patent No. 0355568A2, Japanese Patent Application Nos. 2-326222, 2-415037, and 2-
No. 266615, No. 2-43791, No. 3-1603
No. 95, No. 2-142635, No. 3-146503.
No. 4-77261. The emulsion of the present invention is disclosed in JP-A-62-1
269958, 62-266538, 63-2
No. 20238, No. 63-305343, No. 59-14
No. 2539, No. 62-253159, JP-A-1-13.
1541, 1-297649, 2-42, 1-158429, 3-226730, 4-1
No. 51649, Japanese Patent Application No. 4-179961, European Patent 0
It can be preferably used as a constituent emulsion of the light-sensitive material of Example 508398A1.

[0059]

EXAMPLES The present invention will now be described in more detail by way of examples, but the embodiments of the present invention are not limited thereto. Example 1 An aqueous gelatin solution [deionized alkali-treated gelatin 25 g, H ₂ O 1.2 liter, NaCl 1 g, HNO ₃ 1 was placed in a reaction vessel.
Adjust to pH 4.0 with N liquid. 40 ° C], and while stirring, Ag-1 solution (AgNO ₃ 0.2 g / ml) and X-1 solution (NaCl
(0.07 g / ml) at 60 ml / min for 20 seconds with simultaneous mixing. After 1 minute, Ag-2 solution (AgNO ₃ 0.02 g / ml) and X-2 solution (KBr 0.015 g / ml) were added at 60 ml / min to 34 times.
Simultaneous mixed additions for seconds. After 1 minute, Ag-1 solution and X-
Solution 1 was simultaneously mixed and added at 60 ml / min for 70 seconds. next
After adjusting the pH of the solution to 5.0 with NaOH 1N solution, H ₂ O ₂ solution (3.
7.0 ml of 1% by weight solution) was added, and the mixture was stirred at 40 ° C. for 5 minutes. Transfer the AgX emulsion to another container for 100 minutes, 4
The temperature was kept constant at 0 ° C. Next, 16 ml of 10 wt% NaCl solution was added, the temperature was raised to 70 ° C., and the mixture was aged for 12 minutes.
AgNO ₃ -1 solution (A was added so that the silver potential of the silver rod placed in the solution (vs. the potential of the saturated calomel electrode at room temperature) was 130 mv.
gNO ₃ 0.1 g / ml) was added. A transmission electron micrograph image (TEM) of a replica of emulsion grains collected at this point
Image), about 78% of the total projected area of AgX grains is (100) tabular grains with an aspect ratio of 4 or more, and about 12%.
Was non-planar fine particles.

Next, Ag-1 solution and X-1 solution were simultaneously mixed and added under the following conditions for 30 minutes while keeping the silver potential at 130 mV to grow particles. The Ag-1 solution was added at a starting flow rate of 12 ml / min and the linear flow rate acceleration amount was 0.08 ml / min, and the X-1 solution was added at a flow rate required to maintain the potential. Observing a TEM image of a replica of the emulsion grains collected at this point, the fine grains were reduced to 1% or less of the total projected area. That is, it shows that the particles grew while the fine particles disappeared. Next, Ag-1 solution and X-3 solution (C
l ^-: Br ^- = 8: 2 molar ratio X ^- salt solution. (1.2 mol / liter) was simultaneously mixed and added for 7 minutes while keeping the silver potential at 100 mv. Furthermore, Ag-1 solution and X-4 solution (C
^{l -: Br - = 6:} X 4 molar ratio ^- salt solution, a 1.2 mol / l), while keeping the silver potential 100 mV, 7 minutes, was simultaneously added. The addition flow rate was 12 ml / min in all cases.

Next, 0.02 mol of AgBr fine grain emulsion-1 (average grain diameter 0.05 μm) was added, and after aging for 5 minutes, the temperature was lowered to 40 ° C., and sensitizing dye 1 was saturated to a saturated adsorption amount. Only 68% was added. After stirring for 8 minutes, a precipitating agent was added, the temperature was lowered to 30 ° C., the pH was adjusted to 4.0, and the emulsion was allowed to settle. After washing the precipitated emulsion with water, a gelatin solution (containing 40 g of alkali-processed gelatin having a methionine content of about 50 μmol / g, 1.0 liter of H ₂ O, pCl 2.8, p
H6.1) was added and redispersed at 38 ° C.

A part of the emulsion was sampled and a TEM image of a replica of the emulsion grains was observed. According to it, 93% of the projected area of all AgX grains are tabular grains whose main plane is a {100} face, right-angled parallelogram, and aspect ratio is 4 or more, and the average grain diameter is 1.2 μm and the average aspect ratio is 1.2 μm. At a ratio of 9.0, the coefficient of variation of the diameter distribution (standard deviation of diameter distribution / average diameter) was 0.25.

Comparative Example 1 Example 1 was repeated except that the addition of H ₂ O ₂ was omitted.
Same as. After rinsing with water and redispersion, observation of TEM images of the replicas of the collected emulsion grains showed that 88% of the projected area of all AgX grains had a {100} plane as the principal plane, a right-angled parallelogram, and an aspect ratio of 4 or more. Tabular grains having an average grain diameter of 1.07 μm and an average aspect ratio of 6.4,
The coefficient of variation of the diameter distribution was 0.23. According to the formulations of Example 1 and Comparative Example 1, 1.0 liters of solutions were prepared before addition of H ₂ O ₂ and immediately before the start of the growth, and the pH of each solution was adjusted to 4.0. Immediately after the preparation, MnO ₂ powder was added to decompose residual H ₂ O ₂ . Then centrifuge to remove MnO ₂
The powder and AgX particles were removed. Was added AgNO ₃ -1 solution while measuring the silver potential of each solution was determined and silver potential, the relationship between the (amount / g gelatin AgNO ₃ -1 solution). However, the silver potential was obtained by putting a silver electrode in the solution and measuring the potential of the silver electrode with respect to a saturated calomel electrode placed outside the solution with a potentiometer. All temperatures are 40 ° C. Where each solution were compared AgNO ₃ -1 solution quantity used in reaching the silver potential of 360 mV, the amount of post-oxidation was reduced to about 20% relative to the amount of pre-oxidation.

The AgX emulsions obtained in Example 1 and Comparative Example 1 were each heated to 55 ° C. and NaCl was added to adjust pCl = 2.0. Hypo was added in an amount of 2 × 10 ^-5 mol / mol Ag, chloroauric acid was added in an amount of 10 ^-5 mol / mol Ag, and the mixture was aged. Then, antifoggant 1 was added in an amount of 10 ^-3 mol / mol Ag. The temperature was raised to 40 ° C., a thickener and a coating aid were added, and the mixture was coated on the TAC base together with the protective layer. Dried and coated sample A,
It was set to B. Apply coating samples A and B through the blue filter to 10
^-It was exposed for ² seconds, developed, passed through a stop solution, a fixing solution, and a washing solution, and dried. The result of the photographic characteristics is A (100)> B (93) in the comparison of (sensitivity / granularity), and it was confirmed that Example 1 is superior in (sensitivity / granularity) to Comparative Example 1. It was The developer used had the following composition. The larger the sensitivity is, the smaller the granularity is. Developer [Methol 2.5 g, L-ascorbic acid 10
g, Nabox 35g, NaCl 0.58g, H ₂ O 1 liter]

[0065]

[Chemical 2]

Example 2 In Example 1, the temperature was set to 70 ° C., and the conditions were the same until aging for 12 minutes. Next, NaCl solution-1 (0.3 g / ml) was added to adjust the silver potential to 70 mV, followed by aging for 3 minutes. Observation of a TEM image of a replica of the emulsion grains collected at this point showed that about 90% of the total projected area of the AgX grains were tabular grains with an aspect ratio of 3.5 or more, and that of non-tabular grains was about 0%. It was Accordingly Cl ^- of the AgX solvent resistance, shows that the non-flat particles are almost completely disappeared. Then Ag
After adding NO ₃ -1 solution and adjusting the silver potential to 90 mV, an AgCl fine grain emulsion having an average grain diameter of 0.07 μm and pCl = 2.8-
1 was added at a rate of 0.016 mol / min while maintaining the potential. After adding for 26 minutes and 25 seconds, it was aged for 3 minutes. Next, coating sample C was obtained in the same manner as in Example 1 after the simultaneous addition of Ag-1 solution and X-3 solution. Observation of a TEM image of a replica of the obtained emulsion grains showed that 95% of the total projected area of the Agx grains was a tabular grain having a principal plane of {100} plane, a right parallelogram and an aspect ratio of 4 or more. , Its average particle diameter is 1.23 μm, and average aspect ratio is 9.
7. The coefficient of variation of diameter distribution was 0.25.

Comparative Example 2 In Comparative Example 1, the temperature was set to 70 ° C., and the same process was carried out until aging for 12 minutes. Next, the steps after adding the NaCl solution-1 were the same as in Example 2. However, AgCl fine grain emulsion-2 was used in place of AgCl fine grain emulsion-1. The coating sample of the prepared emulsion was designated as D. The AgCl fine grain emulsion-1 is an aqueous solution of alkali-treated gelatin (25 wt.
A solution of AgNO ₃ (0.2 g / ml of AgNO ₃ ) and an aqueous solution of NaCl (containing only 1.5% by weight of the gelatin, 0.07 g / ml of NaCl) in a 2.5 wt% solution (1.2 liters). It is an emulsion formed by adding for 4 minutes. Next, 10 ml of H ₂ O ₂ solution (3.1% by weight) was added and left standing for 17 hours. The complex forming ability with Ag ⁺ of the dispersion medium after the oxidation treatment was reduced to 20%. AgCl fine grain emulsion-2 is the same as the above-1, but refers to an emulsion to which H ₂ O ₂ is not added. Coating sample C,
D was exposed for 10 ^-2 seconds through a blue filter, developed, passed through a stop solution, a fixing solution and a washing solution, and dried. The result of the photographic characteristics is C in the comparison of (sensitivity / granularity).
(100)> D (91), and it was confirmed that Example 2 was superior to Comparative Example 2 in (sensitivity / granularity).

Example 3 An aqueous gelatin solution [1.5 g of alkali-processed gelatin having a molecular weight of 20,000 (20,000 Gel.), 1.2 g of KBr and H ₂ O was placed in a reaction vessel.
Including 1.2 liters placed adjusted] to pH3.0 with HNO ₃ 1N solution, while maintaining the temperature at 30 ° C., AgNO ₃ -1 solution and X-31 solution (7.2 g of KBr in 100 ml, 2 10,000 Gel.
0.15 g, adjusted to pH 3.0 with 1N HNO ₃ solution) was co-mixed at 50 ml / min for 1 min. After stirring for 1 minute, 12 ml of KBr-31 solution (KBr 0.3 g / ml) was added, and the temperature was raised to 70 ° C. After the temperature was raised, the mixture was aged for 8 minutes, AgNO ₃ -1 solution was added, and the silver potential of the solution was adjusted to -5 mV. Next, NH ₄ NO ₃ solution (0.5 g / ml) 5.5 ml, NH ₃
Liquid (0.25 g / ml) 5.5 ml, H ₂ O 30 ml, KOH 1N
The liquid (3.0 ml) was mixed and added, and the mixture was aged for 7 minutes. The pH at this time was 8.3. Transfer emulsion to another container, 40 ℃
I chose Gelatin solution (Alkali-treated bone gelatin 20
g, containing 135 ml of H ₂ O) and HNO ₃ 3N solution were added to adjust the pH to 5.2. Next, H ₂ O ₂ solution (3.1 g / 100
4 ml) was added, mixed, and allowed to stand for 3 hours. Next, the emulsion was transferred to a reaction vessel, and a polyalkylene oxide compound (PP-described in Japanese Patent Application No. 5-263128) was stirred while stirring.
2 and PE-2) were added in an amount of 3 g each. The temperature was raised to 60 ° C., and 7 ml of KBr-31 solution was added.

Ag-1 solution and X-32 solution (KBr 0.145 g
/ Ml), the starting flow rate of Ag-1 solution is 15 ml / min, the linear flow rate acceleration is 0.6 ml / min for 28 minutes, and the silver potential is -30.
It was added while keeping it at mV. Add a precipitating agent and raise the temperature to 30
The temperature was lowered to 0 ° C., the pH was adjusted to 4.0, and the emulsion was precipitated. After washing the precipitated emulsion with water, a gelatin solution (methionine content of about 5
60 g of 0 μmol / g gelatin and 1.5 liter of H ₂ O were added, pBr 2.8, pH 6.5) was added, and the mixture was redispersed at 38 ° C. A part of the emulsion was sampled and a TEM image of the emulsion grain replica was observed. According to it, 99.9% or more of the total projected area of AgX grains are hexagonal tabular grains whose main planes are {111} faces (adjacent edge ratio <2), and their average grain diameter is 1.0 μm and average aspect ratio is 1.0 μm. At a ratio of 9.0, the coefficient of variation of the diameter distribution was 0.06.

Comparative Example 3 The same as Example 3 except that the addition of H ₂ O ₂ was omitted. The TEM image of the obtained emulsion grain replica was observed. 99.9% or more of the total projected area of the AgX grains are hexagonal tabular grains whose main planes are {111} planes (neighboring side ratio <2), whose average grain diameter is 0.94 μm and average aspect ratio is 8. At 0, the coefficient of variation of the diameter distribution was 0.11. In each of the emulsions obtained in Example 3 and Comparative Example 3, 4
The sensitizing dye-2 solution was added directly to the liquid at 0 ° C. by 70% of the saturated adsorption amount in the liquid. Next, a gold sensitizer [chloroauric acid: KSCN = 1: 10 molar ratio mixture] was added in an amount of 10 ⁻⁵ mol / mol AgX in terms of gold amount, and after 3 minutes, chemical sensitizer-1 was added to 1.8 ×. Only 10 ⁻⁵ mol / mol AgX was added. Next, the temperature was raised to 60 ° C., aging was performed for 20 minutes, and then the temperature was lowered to 40 ° C. Antifoggant (4-hydroxy-6-methyl-
1,3,3a, 7-tetrazaindene) 3.5 × 10
Only ^-3 mol / mol AgX was added, and the thickener, coating aid, and hardener were added and coated on the TAC base. The coating samples E and F were dried. The coated sample was exposed for 10 ^-2 seconds through a blue filter and an optical wedge. Next, it was developed by MAA-1 development at 20 ° C. for 10 minutes, stopped, fixed, washed with water and dried. Relative (sensitivity / fog) ratio is sample E (100)> sample F
(91), and it was confirmed that Example 3 was superior to Comparative Example 3 in terms of (sensitivity / fog) ratio.

[0071]

[Chemical 3]

According to the formulations of Example 3 and Comparative Example 3, the solutions in the state before the addition of H ₂ O ₂ and immediately before the start of the growth were adjusted to 1.0.
Each liter was prepared and the pH of the solution was adjusted to 4.0. Immediately after the preparation, MnO ₂ powder was added to decompose residual H ₂ O ₂ . Next, MnO ₂ powder and AgX particles were removed by centrifugation.
The relationship between the silver potential at 40 ° C. of the solution (addition amount / g gelatin AgNO ₃ -1 solution) was determined. Where each solution were compared AgNO ₃ -1 solution quantity used in reaching the silver potential of 360 mV,
The addition amount was reduced to about 25% by the oxidation. The above results are summarized in Table 1.

[0073]

[Table 1]

[0074]

When an AgX emulsion containing AgX grains produced by the method of the present invention is coated on a support and dried,
A photographic light-sensitive material having excellent sensitivity and graininess as compared with the conventional method can be obtained.

[Brief description of drawings]

FIG. 1 shows the reaction of compounds A ₁ and A ₂ , resulting in reaction products B ₁ ,
The relation of standard oxidation potential of each compound when B ₂ is generated is shown.

Claims (5)

[Claims] 1. A method for producing silver halide grains by adding silver ions and halogen ions to a dispersion medium solution containing at least a dispersion medium and water, wherein 10 seconds after the start of nucleation and 5 minutes after the end of grain growth. Until then, the complex-forming ability with Ag ⁺ per unit weight of the dispersion medium under the same conditions was 1
A method for producing silver halide grains, which comprises reducing the amount by 0% or more. 2. The method for producing silver halide grains according to claim 1, wherein the silver halide grains are tabular grains having an aspect ratio (grain diameter / thickness) ≧ 1.8. 3. The method for producing silver halide grains according to claim 2, wherein 25% or more of the reduction is carried out after the nucleation of the tabular grains and before the growth. 4. The production of silver halide grains according to claim 1, wherein the reduction is carried out by adding an oxidizing agent to the dispersion medium solution and oxidizing the dispersion medium. Method. 5. The method for producing silver halide grains according to claim 1, wherein the dispersion medium is gelatin.