JP2709799B2 - Method for producing silver halide emulsion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a silver halide (hereinafter referred to as Ag)
X)).

[0002]

2. Description of the Related Art The photographic properties of tabular AgX grains having parallel twin planes are excellent, as described in JP-A-63-11928, but can be produced by a conventionally known method for producing tabular grains. As a result, in addition to the tabular grains, grains having two or more non-parallel twin planes and single twin grains were mixed, and it was impossible to make the tabular grains alone 95% or more of the projected area of all grains. Even at such a low ratio, when non-tabular grains are mixed, there is a problem in that the image quality is deteriorated. In particular, AgX photographic light-sensitive materials composed of monodisperse tabular grains having a narrow particle size distribution have good image quality. Therefore, even at such a low ratio, there is a problem that non-tabular grains are mixed. A conventional method for producing tabular grains is described in JP-A-58-113.
No. 926, No. 58-113927, No. 58-1139
Nos. 28 and 62-157024 can be referred to, but there is no description of a method for solving this problem.

[0003]

SUMMARY OF THE INVENTION The first object of the present invention is to provide a method for producing an AgX emulsion comprising tabular AgX grains, which has a low mixing ratio of nontabular grains. A second object of the present invention is to provide a method for producing an AgX emulsion comprising monodisperse tabular AgX grains having a hexagonal main surface and a small mixing ratio of nontabular grains.

[0004]

This and other objects have been achieved by the present invention described below. (1) A method for producing a silver halide emulsion containing tabular silver halide grains containing parallel twin planes by sequentially performing nucleation, Ostwald ripening, and grain growth steps of silver halide grains. A method for producing a silver halide emulsion, wherein the aqueous silver salt solution contains 0.05 to 2.0% by weight of a dispersion medium among the aqueous silver salt solution and the aqueous alkali halide solution which are sometimes added. (2) The silver halide emulsion according to (1), wherein both the aqueous silver salt solution and the aqueous alkali halide solution added at the time of nucleation contain 0.05 to 2.0% by weight of a dispersion medium. Production method. (3) The method for producing a silver halide emulsion as described in (1) or (2) above, wherein the dispersion medium is low-molecular-weight gelatin having a molecular weight of 500 to 60,000. (4) The tabular grains have a projected area of 9 of all silver halide grains.
The method for producing a silver halide emulsion according to the above (1), which accounts for 5% or more.

[0005] In the method for producing an AgX emulsion of the present invention, an Ostwald ripening step is performed following the nucleation of AgX grains. Preferably, a grain growth step is performed after Ostwald ripening. This method is disclosed in JP-A-51-39027 and 63-11928.
No.

1) Nucleation In such a production method, nucleation is preferably carried out using low molecular weight gelatin as a dispersion medium and under conditions of pBr 1.0 to 2.5. In this case, the low molecular weight gelatin has a molecular weight of 70,000 or less, preferably 500 to 60,000, and more preferably 1000 to 40,000. When the average molecular weight is 70,000 or more, the effect of the present invention (95% or more of the projected area of all AgX grains becomes hexagonal tabular grains) is reduced. When the average molecular weight is 500 or less, there is a problem in the production of gelatin. It is preferable that 50% by weight or more, preferably 70% by weight or more of the dispersion medium is low molecular weight gelatin. The concentration of the dispersion medium can be 0.05 to 5% by weight.
A low concentration range of 1.6% by weight is particularly effective. The reason is, as described in JP-A-63-11928,
Twin plane formation frequency can be increased under low Br ^- concentration,
This is because the effect of the present invention can be increased.

As the kind of gelatin, alkali-treated gelatin is usually used, but modified gelatin such as acid-treated gelatin and phthalated gelatin can also be used. The frequency of twin plane formation during nucleation depends on various supersaturation factors (temperature during nucleation, gelatin concentration, addition rate of silver salt aqueous solution and alkali halide aqueous solution, Br ^- concentration, stirring rotation speed, halogen added) I in alkali aqueous solution ^- content silver halide solvent content, pH, depending on the salt concentration (such as KNO _3, NaNO _3), etc.), the dependence of JP 63-92942 by the present inventors It is shown in the figure. Specifically, while observing the dependence of these figures, the probability that two twin planes are formed in parallel per grain during nucleation increases, and the form of the finally formed silver halide grains is It is carried out by adjusting these various supersaturation factors so as to fall within the condition range of the emulsion of the present invention. More specifically, the condition of the supersaturation factor at the time of nucleation may be adjusted while observing the finally formed replica image of the silver halide grains with a transmission electron microscope.

Normally, when these supersaturation factors are increased, the resulting particles are a) octahedral regular particles → b) particles having a single twin plane → c) particles having two parallel twin planes (Object) → d) Particles having non-parallel twin planes and e) 3
These supersaturation factors are changed so that the abundance ratio of the particles of c) falls within the range of the effects of the present invention in the particles finally obtained, although the particles change like particles having two or more twin planes. To adjust.

By observing the finally obtained tabular grains by controlling these various factors, the tabular grains obtained by forming nuclei under the above-mentioned conditions show that the tabular grains obtained by nucleation have a usual average molecular weight of 100,000 It was found that the mixing ratio of non-tabular grains was particularly low as compared with the case where gelatin was used as a dispersion medium. Also,
As the shape, the ratio of hexagonal tabular grains having an adjacent side ratio of 2 or less described in JP-A-63-151618 is high. Other preferable conditions at the time of nucleation are as follows. Of the silver salt aqueous solution and the alkali halide aqueous solution added at the time of nucleation, it is preferable to use an aqueous solution in which the silver salt aqueous solution side or both aqueous solutions contain 0.05 to 2.0% by weight of a dispersion medium. As a dispersion medium in this case, ordinary photographic gelatin can be used, but the above-mentioned low molecular weight gelatin is more preferable. The temperature is preferably from 5 to 60C, more preferably from 15 to 50C. The I ^- content in the previously charged solution is preferably 0.03 mol / l or less, more preferably 0.01 mol / l or less. AgNO
The addition rate of ₃ is 0.5 g per 1 liter of the aqueous solution.
/ Min to 30 g / min is preferred.

[0010] The composition of the alkali halide solution added, Br ^- for I ^- content is solid solubility limit of AgBrI generating less, preferably 10 mol% or less. The concentration of the unrelated salt in the reaction solution is preferably from 0 to 1 mol / liter. Although the pH of the reaction solution can be 2 to 10,
When a reduction sensitized silver nucleus is introduced, it is preferably from 8.0 to 9.5. The concentration of the AgX solvent in the reaction solution is from 0 to 3.
0 × 10 ⁻¹ mol / l is preferred. The following AgX solvents can be used.

2) Aging In the nucleation described in 1), fine tabular grain nuclei are formed, but a large number of other fine grains (especially octahedral and single twin grains) are simultaneously formed. Before the next growth process, it is necessary to eliminate grains other than tabular grain nuclei to obtain nuclei having a shape to be tabular grains and having good monodispersity. As a method for making this possible, a method of performing Ostwald ripening following nucleation is known.

The ripening method is disclosed in Japanese Patent Application Laid-Open No. 63-151.
In addition to the items described in No. 618, the following method is also effective. After nucleation, a part of the emulsion is taken out as a seed crystal, and an aqueous gelatin solution is added, or simply an aqueous gelatin solution is added after nucleation to adjust pBr and gelatin concentration. The preferred pBr in this case is 1.3 to 2.0, and the gelatin concentration is 1 to 10% by weight. The gelatin used in this case is preferably gelatin generally having an average molecular weight of 100,000 to 300,000 which is often used in the photographic industry. Next, when the temperature is increased and the first aging is performed, tabular grains grow and non-tabular grains disappear. Next, an aqueous solution of AgNO ₃ is added, and the pB of the solution is increased.
After adjusting r to 1.8 to 3.5, an AgX solvent is added and a second aging is performed. The preferred AgX solvent concentration in this case is 0 to 3
× 10 ^-1 M / liter, more preferably 10 ^-4 to 2 × 1
0 ^-1 M / liter. Aged in this way, almost 1
Only 00% tabular grains.

3) Growth In the present invention, after Ostwald ripening, it is preferable to go through a grain growth step. In the present invention, the crystal growth period following the ripening process is preferably maintained at pBr 1.4 to 3.5. Further, the addition rate of silver ions and halogen ions during the crystal growth period is set to 20 to 100% of the critical crystal growth rate,
It is preferable to set the addition rate so that the crystal growth rate is preferably 30 to 100%. That is, as the growth atmosphere during the crystal growth period, a low pAg is preferable, and the higher the degree of supersaturation, the more monodispersed the tabular grains are with the growth.

In this case, the method of adding silver ions and halogen ions together with the crystal growth can be referred to the description in JP-A-63-151618. An AgX solvent can be used to promote growth during the crystal growth period. In that case, the concentration of the AgX solvent is 0
-0.3 mol / liter is preferable, and 0-0.1 M / liter is more preferable. The preferred range and more preferred range of the halogen composition of AgX referred to in the present invention are different at the time of nucleation, crystal growth, and the whole AgX grains. The range is shown in Table 1. Table 2 summarizes the preferable preparation conditions.

[0015]

[Table 1]

[0016]

[Table 2]

The emulsion prepared by the method of the present invention comprises
Preferably it is mainly composed of silver iodobromide grains, but the internal distribution of silver iodide may be uniform or have a high internal concentration, may have a high surface concentration, may be an increasing type or a steep type,
They can be used for different purposes. The low molecular weight gelatin used in the present invention can be usually prepared as follows. Average molecular weight commonly used 10
Ten thousand gelatins are dissolved in water, and gelatin molecules are enzymatically decomposed by adding gelatinolytic enzymes. See RJCox, Photographic Gelatin II, Academic Pres
s, London, 1976, p. 233-251, p. 3
35 to 346 can be referred to. In this case, since the bonding position at which the enzyme is decomposed is determined, low molecular weight gelatin having a relatively narrow molecular weight distribution can be obtained, which is preferable. In this case, the longer the enzymatic decomposition time, the lower the molecular weight. The enzyme is then usually deactivated, such as by heating. In addition, low pH (pH 1-3) or high pH (pH 10
12) There is also a method of heating and hydrolyzing in an atmosphere.

The silver halide grains of the present invention can be used as emulsions by themselves, but the grains may be used as a core to form a core / shell type direct reversal emulsion, which may be used. This is described in
Example 13 of US Pat. No. 151618 and US Pat.
No. 61,276, No. 4,269,927, No. 3,
No. 367,778 can be referred to. Further, the tabular grains may be used as a core to form a shallow inner latent emulsion. This is disclosed in JP-A-59-133542.
No., British Patent No. 145876 can be referred to. Alternatively, the tabular grains may be used as host grains to form epitaxial grains. With respect to this, reference can be made to JP-A-58-108526, JP-A-57-133540 and JP-A-62-32443.

Further, the tabular grains may be used as substrate grains to form ruffled grains. In this regard, reference can be made to U.S. Pat. No. 4,643,966. The tabular grains may be used as cores to form grains having dislocation lines therein. For this, the description in JP-A-63-220238 can be referred to. The tabular grains can be used in a high hardening system. This is described in JP-A-58-113926, Research D
isclosure, volume 184, August 1979, item 18
431, section K can be referred to.

In addition, H ₂ O ₂ ,
A method of adding an oxidizing agent such as a peroxy acid and then adding a reducing substance, or a method of reducing free gold ions in the photographic material after gold-sensitized ripening can be used. This is described in JP-A-61-3134 and JP-A-61-3136.
JP-A-62-54249, JP-A-61-2199
No. 48, No. 61-219949, JP-A-63-401
Nos. 37 and 63-40139 can be referred to. The tabular grains may be spectrally sensitized with an antenna dye.
This is described in JP-A-62-209532 and JP-A-6-209532.
The description of 3-13841 and 63-138342 can be referred to. Further, AgX layers having different halogen compositions may be laminated in a direction perpendicular to the main plane of the tabular grains, using the tabular grains of the present invention as a substrate.
Regarding this, reference can be made to JP-A-63-106746. In this case, the AgX layer to be laminated is Ag
Br, AgBrClI (Iodine content 0 to solid solution limit, Cl content 0 to 1
00 mol%) is more preferred.

With respect to the use of the light coherence of the tabular grains, the details of the above items, and other items, reference can be made to JP-A-63-151618. In the nucleation process of the present invention, a silver halide solvent may be used to adjust the supersaturation condition for determining the frequency of twin plane formation. In the ripening process of the present invention, a silver halide solvent may be used to promote ripening and, during the crystal growth period after the ripening, to promote crystal growth.

Examples of frequently used silver halide solvents include thiocyanates, ammonia, thioethers and thioureas. For example, thiocyanates (U.S. Pat. Nos. 2,222,264 and 2,44)
8,534, 3,320,069), ammonia, thioether compounds (for example, US Pat.
No. 71,157, No. 3,574,628, No. 3,
Nos. 704,130, 4,297,439, and 4,276,347), and thione compounds (eg, JP-A-53-144319, JP-A-53-82408, and JP-A-55-77737). And amine compounds (for example, JP-A-54-100717). Other constitutions of the emulsion layer of the photographic material using the silver halide emulsion obtained in the present invention are not particularly limited, and various additives can be used as needed.

Chemical sensitizers, spectral sensitizing dyes, antifoggants, stabilizers, metal ion dopes, silver halide solvents, dyes, color couplers, DIR couplers, binders, hardeners, coating aids which can be added Agents, thickeners, emulsion precipitants, plasticizers, dimensional stability improvers, antistatic agents, fluorescent brighteners, lubricants, matting agents, surfactants, UV absorbers, scattering or absorbing materials, curing agents, Anti-adhesion, photographic property improvers (eg, development accelerators, contrast agents, etc.), and photographically useful fragments such as developers (development inhibitors or accelerators, bleaching accelerators, developers, silver halide solvents, toners, Hardeners, antifoggants, competing couplers, couplers that release chemical or spectral sensitizers and desensitizers, etc., image dye stabilizers, self-suppressing developers, and their uses, as well as supersensitizers in spectral sensitization. Sensitization, spectral sensitization color The halogen acceptor effect and the electron acceptor effect, the preparation of antifoggants, stabilizers, development accelerators or inhibitors, and other production equipment, reaction equipment, stirring equipment, coating and drying methods used in the production of the emulsion of the present invention. , Exposure method (light source, exposure atmosphere, exposure method), and photographic support, microporous support, undercoat layer, surface protective layer, matting agent, intermediate layer,
Regarding the antihalation layer, the photographic processing agent, and the photographic processing method, Research Disclosure Magazine, Vol.
1978, December issue (item 17643), 1
Volume 84, August 1979 (Item 18431), Volume 134, June 1975 (Item 13452) Product, Licensing Index, Volume 92, 107-
110 (December 1971), JP-A-58-11392
Nos. 6, 58-113927 and 58-11328
No. 61-3134, JCIA Monthly Report 1984, 12
Monthly Issue, p. 18-27 TH James, The Theory of The P
hotographic Process, Fourth Edition, Macmillan, Ne
w York, 1977, Making, by VLZelikman et. al.
and Coating Photographic Emulsion. (The Focal Pres
s, 1964) and JP-A No. 62-6251. The silver halide emulsion of the present invention may be used, if necessary, together with other emulsions, protective layers, intermediate layers and filter layers on one or more layers (for example, two layers,
3 layers). 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. Regarding this layer structure, see JP-A-61-3134 and JP-A-63-1.
No. 51618 can be referred to.

The silver halide emulsion of the present invention can be used as a black-and-white silver halide photographic light-sensitive material (for example, an X-ray light-sensitive material, a lithographic light-sensitive material, a negative film for black-and-white photography) or a color photographic light-sensitive material (for example, a color negative film, Color reversal film, color paper, silver dye bleaching method, etc.). Further, it is used for a light-sensitive material for diffusion transfer (for example, a color diffusion transfer element, a silver salt diffusion transfer element), a silver dye bleaching method, and a heat-developable light-sensitive material (black and white, color) as described in US Pat. No. 4,500,626. be able to. The emulsion of the present invention was prepared in Example 1 of JP-A-62-269958,
Examples 13 and 14 of JP-A-62-141112 and JP-A-63-151618, Example 9 of JP-A-1-131541, JP-A-62-266538 and JP-A-63-22023.
8, JP-A-1-131547 and JP-A-1-158429
, Nos. 1-298038 and 2-42.

[0025]

The AgX emulsion grains of the present invention thus obtained can provide AgX emulsions having high image quality and photographic characteristics, since 95% or more of the projected area of all grains are tabular grains. Also, 93% or more of the projected area of all the grains are hexagonal monodisperse tabular grains having an adjacent side ratio of 2 or less, so that an AgX emulsion having high-quality photographic characteristics can be provided.

[0026]

【Example】

Example 1 In a reaction vessel having a capacity of 4 liters, an aqueous gelatin solution (1000 ml of water, 7 g of enzyme-treated low molecular weight gelatin (average molecular weight: 20,000), 4.5 g of KBr, pH 6.0 with 1 NKOH aqueous solution).
The regulation, pBr 1.42) placed, while maintaining the solution temperature at 30 ° C., and an aqueous solution of AgNO ₃ 25 ml (including the AgNO ₃ 8 g and low molecular weight gelatin 0.16 g), KBr aqueous solution 25 ml (KB
r 5.8 g and the low molecular weight gelatin (including 0.16 g) were added simultaneously over 1 minute (flow rate 25 ml / min), stirred for 1 minute, 350 ml of the seeds were used as seed crystals, and gelatin aqueous solution [ 650 ml of water, 20 g of deionized alkali-treated gelatin (average molecular weight 100,000), 1.2 g of KBr, pH
8.0] and raise the temperature to 75 ° C.

At this time, pBr is 1.79. After aging for 40 minutes after the temperature was raised, an aqueous solution of AgNO ₃ (containing 1.8 g of AgNO ₃ ) was added, and then 6 ml of NH ₄ NO ₃ (50% by weight) and 6 ml of NH ₃ (25% by weight) were added. And aged for 25 minutes. A transmission electron micrograph (TE
M) is shown in FIG. The projected area ratio of tabular grains to the total projected area of the emulsion grains was 99%.

Next, the temperature was lowered to 60 ° C., and the pH was lowered to 7.0 with HNO ₃ 1N solution.
To 0, AgNO ₃ aqueous solution (containing 10g of AgNO ₃ in 100ml) and the beginning of 10 minutes using a KBr aqueous solution 10 ml /
The CDJ was added at a silver potential (vs. saturated calomel electrode) of -20 mV at 15 ml / min for the next 20 minutes. FIG. 2 shows a TEM image of the emulsion grains obtained at this time. The ratio of the projected area occupied by the tabular grains to the total projected area of the emulsion grains is 99.
5%. This emulsion was sensitized with gold and sulfur, an antifoggant and a hardener were added, coated, and subjected to wedge exposure. As expected, improvements in image quality such as graininess and sharpness were observed as compared with the conventional method.

Example 2 Particles were formed in the same manner as in Example 1 except that the gelatin at the time of the formation was replaced with gelatin having an average molecular weight of 2,000, 5,000, 10,000, 40,000 and 100,000. The ratio of the projected area of the tabular grains to the projected area of all grains was determined from the TEM image of the obtained AgX emulsion grains, and is shown in FIG. It can be seen that the projected area ratio of the tabular grains is high in an average molecular weight of 5,000 to 40,000. The projected area ratio of hexagonal tabular grains obtained in the case of gelatin having an average molecular weight of 100,000 was 90%.
And that of Example 1 was 99%, and the ratio of hexagonal tabular grains was also high. The average molecular weight of gelatin was measured by a gel filtration chromatogram method.

[Brief description of the drawings]

FIG. 1 is an electron micrograph showing the structure of silver halide crystal grains in a silver halide emulsion obtained in Example 1, at magnifications of 4,300 and 2,900.

FIG. 2 is an electron micrograph showing the structure of silver halide crystal grains in the silver halide emulsion obtained in Example 1, with magnifications of 4,300 and 2,900.

FIG. 3 is a graph showing the relationship between the average molecular weight of gelatin at the time of formation and the ratio of tabular grains in an emulsion in Example 2, with the horizontal axis representing the average molecular weight of gelatin and the vertical axis representing the projected area of the tabular grains. (%).

Claims (4)

(57) [Claims] 1. A method for producing a silver halide emulsion containing tabular silver halide grains containing parallel twin planes by sequentially passing through nucleation, Ostwald ripening and grain growth steps of silver halide grains, A method for producing a silver halide emulsion, wherein the aqueous silver salt solution contains 0.05 to 2.0% by weight of a dispersion medium among the aqueous silver salt solution and the aqueous alkali halide solution added during nucleation. 2. An aqueous silver salt solution and an aqueous alkali halide solution to be added at the time of nucleation both contain a dispersion medium of 0.05 to 2.
2. The method for producing a silver halide emulsion according to claim 1, wherein said silver halide emulsion contains 0% by weight. 3. The method for producing a silver halide emulsion according to claim 1, wherein said dispersion medium is low molecular weight gelatin having a molecular weight of 500 to 60,000. 4. The method according to claim 1, wherein said tabular grains occupy 95% or more of the projected area of all silver halide grains.
A method for producing a silver halide emulsion as described above.