JPH0789200B2 - Method for producing silver halide emulsion - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a silver halide (hereinafter referred to as AgX) emulsion.

(Prior Art and its Problems) Although tabular AgX grains containing parallel twin planes have excellent photographic characteristics as described in JP-A-63-11928, the production of tabular grains known in the prior art When produced by the method, in addition to tabular grains, grains having two or more non-parallel twin planes or single twin grains are mixed, and only tabular grains have a projected area of all grains.
It was able to reach 95% or more.

Even with such a low ratio, when non-tabular grains are mixed,
This was a problem because it deteriorated the image quality.

Especially Ag composed of monodisperse tabular grains with a narrow grain side distribution.
Since the image quality of the X photographic light-sensitive material is good, the inclusion of non-tabular grains was a problem even at such a low ratio.

For the conventional method for producing tabular grains, see JP-A-58-1139.
No. 26, No. 58-113927, No. 58-113928, No. 62-157024
The description in the issue can be consulted, but it does not describe how to solve this problem.

(Object of the Invention) An object of the present invention is, firstly, to provide a method for producing an AgX emulsion comprising tabular AgX grains having a small mixing ratio of non-tabular 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 shape with a small mixing ratio of non-tabular grains.

DISCLOSURE OF THE INVENTION Such an object has been achieved by the present invention described below.

That is, the present invention, the nucleation of AgX grains and subsequent Ostwald ripening, or nucleation Ostwald ripening, by going through the order of grain growth by containing tabular AgX grains containing parallel twin planes by the order of AgX grains. A method for producing an emulsion, wherein the dispersion medium is low molecular weight gelatin and pBr1.0
A method for producing an AgX emulsion, which is characterized in that nucleation is performed under a condition of up to 2.5.

(Specific Structure of the Invention) In the method for producing an AgX emulsion of the present invention, the Ostwald ripening step is performed subsequent to 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.

1) Nucleation In such a production method, nucleation is carried out by using a low molecular weight gelatin as a dispersion medium and nucleating under the condition 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 1,000 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) decreases. When the average molecular weight is 500 or less, there are problems in producing 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.

Although the concentration of the dispersion medium may be 0.05 to 5% by weight,
The low concentration range of 0.05 to 1.6% by weight is particularly effective. The reason for this, as are also noted in JP-A-63-11928, low Br ^-
This is because the twin plane formation frequency can be increased under a high concentration, and the effect of the present invention can be enhanced.

Alkali-treated gelatin is usually used as the type of gelatin, 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 ^- content in aqueous alkali halide solution, amount of silver halide solvent, pH, salt concentration (KNO ₃ , NaNO _3, etc.))
It is shown in the figure at −238808. Specifically, looking at the dependence of these figures, the probability that two twin planes are formed in parallel per grain during nucleation is high, and the morphology of the finally formed silver halide grains is It is carried out by adjusting these various supersaturation factors so that they fall within the range of the conditions of the emulsion of the present invention. More specifically, the conditions of the supersaturation factor at the time of nucleation may be adjusted while observing the replica image of the finally formed silver halide grains with a transmission electron microscope.

Usually, when these supersaturation factors are increased, the particles produced are a) octahedral regular particles → b) particles having a single twin plane → c) particles having two parallel twin planes (purpose) ) → d) particles having non-parallel twin planes and e) particles having three or more twin planes, but the abundance ratio of the particles of c) is the same in the finally obtained grains. These various supersaturation factors are adjusted within the range of the effect of the invention.

When these various factors are adjusted and the tabular grains finally obtained are observed, the tabular grains obtained by nucleation using the above-mentioned conditions disperse a usual tabular molecular weight photographic gelatin of 100,000. It was found that the mixing ratio of non-tabular grains was particularly low as compared with the case of using it as a medium. Further, as a shape, the ratio of hexagonal tabular grains having an adjacent side ratio of 2 or less as described in Japanese Patent Application No. 61-299155 is high. Other preferable conditions during nucleation are as follows. It is preferable to use an aqueous solution containing 0.05 to 2.0% by weight of a dispersion medium in the aqueous solution of silver salt or both of the aqueous solution of silver salt and the aqueous solution of alkaline halide added at the time of nucleation. As the 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 5 to 60 ° C, preferably 15 to 50 ° C.
The I ⁻ content in the solution charged in advance is preferably 0.03 mol / or less, more preferably 0.01 mol / or less. The addition rate of AgNO ₃ is preferably 0.5 g / min to 30 g / min per reaction aqueous solution.

The composition of alkali halide solution added, Br ^-
It is preferable that the I ^- content relative to is less than the solid solubility limit of AgBrI to be formed, preferably 10 mol% or less.

The irrelevant salt concentration in the reaction solution is preferably 0 to 1 mol /.
The pH of the reaction solution may be 2 to 10, but when introducing reduction-sensitized silver nuclei, it is preferably 8.0 to 9.5. The concentration of the AgX solvent in the reaction solution is preferably ^{0 to} 3.0 × 10 ^-1 mol /. The type of AgX solvent may be the one described below.

2) Aging In the nucleation described in 1), fine tabular grain nuclei are formed, but at the same time, a large number of other fine particles (especially octahedral pairs and single twin grains) are formed. Before starting the growth process described below, it is necessary to eliminate grains other than the tabular grain nuclei to obtain nuclei which are formed to be tabular grains and have good monodispersity. As a method of making this possible, a method of performing Ostwald ripening after nucleation is known.

As the aging method, the following method is effective in addition to the matters described in Japanese Patent Application No. 61-299155.

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. In this case, the preferable pBr is 1.3 to 2.0 and the gelatin concentration is 1 to 10% by weight. The gelatin used in this case has an average molecular weight of 10 commonly used in the photographic industry.
10,000 to 300,000 gelatin is preferred.

Next, when the temperature is raised and the first ripening is carried out, tabular grains grow and non-tabular grains disappear. Next, an AgNO ₃ aqueous solution is added to adjust the pBr of the solution to 1.8 to 3.5, and then an AgX solvent is added to perform second aging. In this case, the preferred AgX solvent concentration is 0 to 3 × 10 ^-1 M /, more preferably 10 ^-4 to 2 × 10 ^-1 M /.
Is.

By aging in this way, only about 100% tabular grains are formed.

3) Growth In the present invention, it is preferable that a grain growth step is performed after Ostwald ripening.

In the present invention, the crystal growth period following the ripening process is pBr1.4-
Keeping at 3.5 is preferred. In addition, it is preferable that the addition rate of silver ions and halogen ions during the crystal growth period is 20 to 100%, preferably 30 to 100%, of the crystal critical growth rate.

That is, as the growth atmosphere during the crystal growth period, low pAg is preferable, and the higher the degree of supersaturation, the more the tabular grains become monodisperse with growth, which is preferable.

In this case, regarding the method of adding silver ions and halogen ions along with the crystal growth, Japanese Patent Application No. 61-299155
Can be referred to.

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 to 0.3.
mol / is preferable, and 0-0.1 M / is more preferable.

The preferable and more preferable range of the halogen composition of AgX in the present invention is different in nucleation, crystal growth, and whole AgX grains, and the range is shown in Table 1. The preferable adjustment conditions are summarized in Table 2.

The emulsion prepared by the method of the present invention preferably consists mainly of silver iodobromide grains, but the silver iodide grain internal distribution may be uniform, high internal concentration, or high surface concentration. It may be a gradually increasing type or a steep type, and can be used properly according to each purpose.

The low molecular weight gelatin used in the present invention can be usually prepared as follows. Commonly used average molecular weight
100,000 gelatin is dissolved in water and gelatin degrading enzyme is added to enzymatically decompose gelatin molecules. For this method, see RLCox, Photographic Gelatin II, Academic Pres.
s, London, 1976, P.233-251, P.335-346 can be referred to. In this case, since the binding position at which the enzyme decomposes is fixed, a 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 inactivated by heating or the like. In addition, low pH (pH 1 ~
3) Alternatively, there is a method of heating under a high pH (pH 10 to 12) atmosphere to perform hydrolysis.

The silver halide grain of the present invention can be used as an emulsion by the above-mentioned silver halide grain itself, but it is also possible to use the grain as a core to form a shell-type direct inversion emulsion and use it. Regarding this, Example 13 of Japanese Patent Application No. 61-299155, and U.S. Pat.Nos. 3,761,276 and 4,269,927.
No. 3 and equivalent 3,367,778 can be referred to.

Further, a shallow inner groove type emulsion may be formed and used by using the tabular grains as a core. Regarding this, JP-A-59-133542
Reference may be had to British Patent No. 145876.

Also, the tabular grains may be used as host grains to form or use epitaxial grains. Regarding this, JP-A-58
-108526, 57-133540, and JP-A-62-32443 can be referred to.

Further, the tabular grains may be used as substrate grains to form raffled grains for use. In this regard, reference can be made to US Pat. No. 4,643,966.

The tabular grains may be used as carp to form grains having dislocation lines inside. Regarding this, Japanese Patent Application No. 62-54640
You can refer to the description of the issue.

The tabular grains can also be used in a highly hardened system.

Regarding this, JP-A-58-113926, Research Disclos
ure, Volume 184, August 1979, Item 18431, Item K can be referenced.

In addition, a method of adding an oxidizing agent such as H ₂ O ₂ or peroxy acid and then adding a reducing substance until the gold sensitization ripening is completed, or a method of adding free gold in the photographic material after gold sensitization aging A method of reducing ions can be used. About this
61-3134, 61-3136, Japanese Patent Application No. 60-96237, JP-A No. 61-219948, No. 61-219949, Japanese Patent Application No. 61-184890.
No. 61-183949 can be referred to. The tabular grains may be spectrally sensitized with an antenna dye. Regarding this, JP-A-62-209532, Japanese Patent Application Nos. 61-284271 and 61-
The description of No. 284272 can be referred to.

Further, using the tabular grain of the present invention as a substrate, an AgX layer having a different halogen composition may be laminated in a direction perpendicular to the main plane of the tabular grain. Japanese Patent Application Sho 61
-253371 can be referred to. In this case, AgBr and AgBrClI (iodine content 0 to solid solution limit, Cl content 0 to 100 mol%) are more preferable as the AgX layer to be laminated.

Regarding the utilization of the optical coherence of the tabular grains, and the details of the above matters and other matters, Japanese Patent Application No. 61-
You can refer to issue 299155.

In the nucleation process of the present invention, a silver halide solvent may be used in order to adjust the supersaturation conditions that determine the twin plane formation frequency.

Further, in the ripening process of the present invention, a silver halide solvent may be used in order to accelerate ripening and in the crystal growth period after this ripening, to promote crystal growth.

Examples of the silver halide solvent often used include thiocyanate, ammonia, thioether, thioureas and the like.

For example, thiocyanate (US Pat. No. 2,222,264, equivalent
2,448,534, equivalent 3,320,069, etc.), ammonia, thioether compound (e.g., U.S. Pat.No. 3,271,157, equivalent 3,574,628, equivalent 3,704,130, equivalent 4,297,439,
Equivalent 4,276,347), thione compounds (eg
3-144319, 53-82408, 55-77737, etc.),
An amine compound (for example, JP-A-54-100717) can be used.

There is no particular limitation on the other constitution of the emulsion layer of the photographic light-sensitive material using the silver halide emulsion obtained in the present invention,
Various additives can be used if necessary.

Chemical sensitizers, spectral sensitizing dyes, antifoggants, stabilizers, metal ion dopes, silver halide solvents, dyes, color couplers, DIR couplers, binders, hardeners, coating aids, sensitizers that can be added. Sticky agent, emulsion precipitation agent, plasticizer,
Dimension stability improver, antistatic agent, fluorescent whitening agent, lubricant, matting agent, surfactant, ultraviolet absorber, scattering or absorbing material,
Hardening agents, anti-adhesion agents, photographic property improving agents (for example, phenomenon accelerators, contrast enhancing agents, etc.), developers, and other photographically useful fragments (development inhibitors or accelerators, bleaching accelerators, developers, etc.)
Silver halide solvents, toners, hardeners, antifoggants, competitive couplers, couplers that release chemical or spectral sensitizers and desensitizers, image dye stabilizers, self-inhibiting developers, and their use, In addition, supersensitization in spectral sensitization, halogen acceptor effect and electron acceptor effect of spectral sensitizing dye, preparation of antifoggant, stabilizer, development accelerator or inhibitor, and other production of the emulsion of the present invention. Manufacturing equipment used, reaction equipment, stirring equipment, coating, drying method, exposure method (light source, exposure atmosphere, exposure method), and photographic support, microporous support, undercoat layer, surface protective layer, matting agent, intermediate layer , Antihalation layer, photographic processing agent, and photographic processing method, Research Discloser magazine, Volume 176, December 1978, December issue (item 17643), Volume 184, August 1979 issue (item
No. 18431), Vol. 134, June 19575 (Item 13452) Product, Taising Indexing Vol. 92, 107-110
(December 1971), JP-A Nos. 58-113926 and 58-113927.
No. 58-113928, No. 61-3134, JCIA Monthly Report 1984
Year, December issue, p.18-27 T.H.James, The Theory of The Ph
otographic Process, Fourth Edition, Macmillan, New Yo
rk, 1977, VL Zelikman et.al., Making and Coati
ng Photographic Emulsion. (Published by The Focal Prss, 1964
Year) and the description of JP-A-62-6251 can be referred to.

The silver halide emulsion of the present invention can be provided on the support together with other emulsions, a protective layer, an intermediate layer and a filter layer in one or more layers (for example, two layers or three layers) if necessary.
Further, it can be provided on both sides of the support, not limited to one side. It is also possible to superimpose emulsions having different color sensitivities.

Regarding this layer structure, the descriptions in JP-A-61-134134 and Japanese Patent Application No. 61-299155 can be referred to.

The silver halide emulsion of the present invention is a black-and-white silver halide photographic light-sensitive material (for example, X-ray sensitive material, squirrel-sensitive material, black-and-white photographic negative film, etc.) and a color photographic light-sensitive material (for example, color negative film, color reversal film). , Color paper, silver dye bleaching method photographs, etc.). Further, 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 photograph, US Pat.
It can also be used for photothermographic materials (black and white, color) such as 4,500,626.

The emulsion of the present invention is prepared in the same manner as in Examples 1 and 62-62 of JP-A-62-269958.
141112, 63-151618, Examples 13 and 14, Japanese Patent Application No. 62-
Example 9 of 203635, 61-109773 and 62-54640
No. 62-208241, No. 62-219173, No. 63-129226
No. 62-263319, and can be preferably used as a constituent emulsion.

(Effects of the Present Invention) The thus obtained AgX emulsion grains of the present invention can provide an AgX emulsion having high-quality photographic characteristics, since 95% or more of the projected area of all grains are tabular grains.

Further, 93% or more of the projected area of all grains are hexagonal monodisperse tabular grains having an adjacent side ratio of 2 or less, and an AgX emulsion having high quality photographic characteristics can be provided.

Example 14 In a reaction vessel having a volume of 4, an aqueous gelatin solution (water 10
00 ml, enzyme-treated low molecular weight gelatin (average molecular weight 20,000) 7
g, KBr4.5g, / pHON adjusted to 6.0 with NKON aqueous solution, pBr1.42) was added, and while keeping the solution temperature at 30 °, 25mL AgNO ₃ aqueous solution (A
8 g of gNO ₃ and 0.16 g of the low molecular weight gelatin) and 25 ml of an aqueous KBr solution (containing 5.8 g of KBr and 0.16 g of the low molecular weight gelatin) were added simultaneously over 1 minute (flow rate 25 ml / min) and stirred for 1 minute. After that, 350 ml of it was used as a seed crystal, and an aqueous gelatin solution [650 ml of water, 20 g of deionized alkali-treated gelatin (average molecular weight 100,000), KBr1.2 g, pH 8.0] was added,
Raise the temperature to 75 ° C. The pBr at this time is 1.79. After aging for 40 minutes after heating, add AgNO ₃ aqueous solution (including 1.8g AgNO ₃ ), then add 6 ml NH ₄ NO ₃ (50 wt%) and NH ₃ (25 wt%).
6 ml was added and aged for 25 minutes. A transmission electron micrograph (TEM) of the emulsion grain replica obtained at this point 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, the pH was adjusted to 7.0 with HNO ₃ / N solution, and 10 ml / min was used for the first 10 minutes using AgNO ₃ aqueous solution (100 g of AgNO ₃ in 100 ml) and KBr aqueous solution. CDJ was added at −20 mV silver potential (vs. saturated calomel electrode) at 15 ml / min for 20 minutes. The TEM image of the emulsion grains obtained at this time is shown in FIG. The projected area ratio of tabular grains to the total projected area of emulsion grains was 99.5%. When this emulsion was subjected to gold-sulfur sensitization, an antifoggant and a hardener were added thereto, and the resultant was exposed to a wedge, as expected, improvements in image quality such as graininess and sharpness were recognized as compared with the conventional method.

Example 2 With the same formulation as in Example 1, only the gelatin at the time of formation was replaced with gelatin having an average molecular weight of 2,000, 5,000, 10,000, 40,000 and 100,000 to form particles. From the TEM image of the obtained AgX emulsion grains, the projected area ratio of tabular grains to the projected area of all grains was determined and shown in FIG. It can be seen that the projected area ratio of the tabular grains increases in the range of the average molecular weight of 5000 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%, that of Example 1 was 99%, and the hexagonal tabular grain ratio was also high.

The average molecular weight of gelatin was measured by gel perchromatogram method.

[Brief description of drawings]

1 and 2 are electron micrographs showing the structure of silver halide crystal grains in the silver halide emulsion obtained in Example 1, and their magnifications are 4,300 times and 2,900 times. 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 the emulsion in Example 2, where the horizontal axis represents the average molecular weight of gelatin and the vertical axis represents the projected area of tabular grains. Is the sum (%) of

Claims (3)

[Claims] 1. A silver halide grain containing tabular silver halide grains containing parallel twin planes, which are formed by nucleation of silver halide grains and subsequent Ostwald ripening, or through nucleation, Ostwald ripening and grain growth in this order. A method for producing a silver halide emulsion, wherein the dispersion medium is low molecular weight gelatin (molecular weight 70,000 or less), and nucleation is carried out under the condition of pBr 1.0 to 2.5. Production method. 2. The method for producing a silver halide emulsion according to claim 1, wherein the nucleation is carried out in an aqueous solution containing 0.05 to 1.6% by weight of a dispersion medium. 3. A method for producing a silver halide emulsion according to claim 1, wherein the tabular silver halide grains account for 95% or more of the projected area of all silver halide grains.