JPH0638151B2 - Method for producing silver halide emulsion - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a silver halide emulsion, and more specifically, a sensor for measuring the silver ion concentration in a silver halide emulsion solution, specifically, a silver ion activity measuring sensor. The present invention relates to a method for producing a silver halide emulsion using an electrode suitable for.

[Prior Art] Generally, a silver halide emulsion widely used in a photographic light-sensitive material in the art is prepared by stirring a water-soluble halogen salt aqueous solution and a water-soluble silver salt aqueous solution in the presence of a protective colloid such as gelatin. It is prepared by mixing while mixing. As such a production technique of a silver halide emulsion, a single jet mixing method, a double jet mixing method and the like are known. The single jet mixing method is a method in which an aqueous solution of a halogen salt is placed in a reaction vessel and stirred, and then an aqueous solution of a silver salt is added at a predetermined addition time to obtain a silver halide crystal. An aqueous solution of gelatin or an aqueous solution of gelatin containing silver halide seed crystals is added to the mixture while stirring, and the aqueous solution of silver salt and the solution of halogen chloride are simultaneously added thereto at predetermined addition times to obtain silver halide crystal grains.

In recent years, in particular, a method for producing a so-called monodisperse emulsion, which is composed of a silver halide crystal having a remarkably narrow grain size distribution and a constant crystal habit, has been extensively studied, especially in the controlled double jet mixing method. As an example of such a manufacturing technique, the one described in JP-A-54-48521 can be mentioned. Monodisperse emulsions have favorable characteristics in terms of photographic characteristics such as high sensitivity, high contrast, and low fog, but in order to make monodisperse emulsions of arbitrary grain size and crystal habit, pH of reaction solution, pAg ( It is important to accurately control the reciprocal of the silver ion concentration) and the addition rate.

The importance of pAg and its control during the production of silver halide emulsions can be understood from the following documents and patents.

Journal of Photographic Science, Volume 12, p242
~ 251 (1964), Vol. 27, p47-53 (1979) show that the crystal habit and shape of silver halide depend on pAg at the time of production.

Regarding differences in chemical ripening characteristics of silver halide emulsions with different crystal habits obtained by controlling pAg, see Journal.
Of Photographic Science (Journal of P
Hotographic Science) Volume 14, p181-184 (1966) and many other reports, pAg at the time of silver halide emulsion production
Are closely related to the photographic properties of the resulting emulsion.

Journal of Photographic Science, Volume 27, p1-1
2 (1979) show that the solubility of silver halide depends on pAg.

Also, the Bulletin of the Society of Scientific Phot
Many reports, such as ography of Japan, Vol. 16, P1-7 (1966), show that the growth rate of silver halide is proportional to the solubility of silver halide.

From these documents, in the production of silver halide emulsion,
It can be seen that pAg determines the growth rate of silver halide.

As described above, in the process of preparing a photographic silver halide emulsion, controlling the pAg of the preparation is an essential condition for obtaining desired photographic characteristics. Conventionally, metal electrodes of silver, gold, platinum, etc. have been generally used as the silver ion sensor used for the above purpose. However, in the measurement of silver ion activity in a system such as a gelatin aqueous solution using a conventional metal electrode as a silver ion sensor, the reproducibility of the measured potential in repeated measurement is not always satisfactory, and the silver halide grain There were variations in size distribution, shape, photographic performance, etc. Further, in continuous measurement for a long time, a drift of the indicated potential occurred, and a problem that the intended silver halide emulsion could not be obtained often occurred.

The cause of the instability in the production of silver halide is not always clarified, but even in a low concentration range up to a silver ion concentration in the silver halide emulsion of up to about 10 ^-10 mol / halogen. It is said that the formation of silver halide crystals is affected, and the sensitivity of conventional silver ion sensors in the low concentration region is considered to be insufficient. Further, it is considered that there is an influence particularly when the silver ion indicating potential lowering phenomenon occurs in the pH range during emulsion preparation by the ammonia method, that is, on the alkali side.

Therefore, in the production of the silver halide emulsion as described above,
The silver ion concentration in the silver halide emulsion is ~ 10 ^-10 mol /
It has been desired to develop a silver ion sensor that can accurately measure the silver ion activity even in a low concentration range and does not cause a decrease in the indicated potential even in the alkaline pH range.

[Object of the Invention] The present invention has been made in view of the above problems, and it is possible to obtain an accurate silver ion activity even in a low concentration range of about 10 ^-10 mol / silver ion concentration in a silver halide emulsion. Can be measured,
Another object of the present invention is to provide a method for producing a silver halide emulsion using a highly reliable silver ion sensor that does not cause the phenomenon of drop of the indicated potential even in the pH range on the alkaline side.

[Structure of the Invention] As a result of various studies conducted by the present inventors on the above-mentioned object,
It has been found that a method for producing a silver halide emulsion while controlling silver ions in the emulsion is achieved by a method for producing a silver halide emulsion using a silver sulfide electrode as a sensor for detecting silver ions.

[Specific Structure of the Invention] The present invention is characterized in that a silver sulfide electrode is used as a silver ion detection control sensor in the production of a silver halide emulsion.

Originally, the silver sulfide electrode had a silver ion concentration of ~ 10 ^-7 mol /
It has been used in the industrial field of chemical analysis and environmental measurement up to about (pAg = 7).

However, utilization of this silver sulfide electrode as a silver ion detection control sensor in the production of silver halide emulsions has not been attempted until now.

Further, generally in the photographic industry, sulfur sensitization using a sulfur compound such as thiosulfate, allylthiourea and thiocyanate is performed for chemical sensitization of silver halide emulsion. The time for performing the physical ripening was after the physical ripening of the silver halide emulsion, and there was a concern that the use of electrodes made of silver sulfide, which is a sulfur compound, as a material during crystal growth of the silver halide grains would adversely affect the physical ripening of the emulsion.

It is a feature of the present invention that good results have been obtained by using a silver sulfide electrode as a silver ion sensor in the process of producing a silver halide emulsion, in contrast to the common knowledge in the art.

The silver sulfide electrode used in the present invention can be obtained, for example, by press-molding a silver sulfide precipitate prepared by placing silver nitrate in a solution of sodium sulfide.

Generally, the ion activity measuring electrode responds selectively to a specific ion, and the potential difference E (V) between the indicator electrode and the reference electrode immersed in the solution is expressed by the following Nernst equation.

Here, E ₀ is the standard potential (V) of the indicator electrode, Is the Nernst coefficient, and a is the ion activity. In the above equation, if E ₀ and the Nernst coefficient are known in advance, the ion activity a can be continuously measured by measuring the potential difference E.

To produce sparingly soluble silver grains in a silver halide emulsion, pH and pAg are monitored and controlled using equipment known in the photographic art. Representative and useful control devices include U.S. Pat. No. 3,031,304 and Photographiche Correspondents.
orrespondens) 103, p161-164 (1967) etc. can be used. In the above, controlling the potential of the reaction solution means changing the potential of the reaction solution according to the potential set with the time from the start of the reaction (at the start of mixing) to the end of the reaction (at the end of mixing). Yes, this includes maintaining a constant potential from the start to the end of the reaction, and changing the potential during the reaction.

Examples of the silver halide include silver bromide, silver chloride, silver iodide,
Silver iodobromide, silver chlorobromide, silver chlorobromoiodide and the like are contained.

The grain diameter of silver halide that can be produced is about 0.1 to 4
Microns are preferred and 0.2-2 microns are particularly preferred.

The particle size distribution may be wide or narrow, but when obtaining particles with a narrow distribution, a particularly large effect is exhibited.

Further, the silver halide grains may have twins or irregular shapes including twins, and may have regular crystal forms such as cubes, octahedra and spheres. It is particularly effective when trying to obtain silver halide grains having a regular crystal form.

Furthermore, the above-mentioned silver halide grains may have a phase different from the inside and the surface, or may be composed of a uniform phase. Further, the particles may be such that the latent image is mainly formed on the surface, or the particles are mainly formed inside the particles.

Representative silver halide solvents include, for example, ammonia, thioethers, thiocyanates, imidazoles, compounds having a thiocarbonyl group bonded to any one of sulfur or oxygen atoms and a nitrogen atom, and thioureas. .

When the silver halide and the organic silver salt obtained here are applied to a photographic material, for example, any type of black-and-white photographic light-sensitive material, color photographic light-sensitive material, and pseudo-color photographic light-sensitive material may be used. , Various X-rays, radiations, heat development, and other photographic applications, and any photographic light-sensitive material of photographic type or mechanically negative type, positive type, diffusion transfer type, etc. You can

Hereinafter, the present invention will be illustrated by examples, but the embodiments of the present invention are not limited thereby.

Specific Examples of the Invention Example 1 As a pAg measurement system, HM-20E pH manufactured by Toa Denpa Kogyo KK
Toa Denpa Kogyo Co., Ltd. is used as a reference electrode terminal using a meter.
The silver-silver chloride electrode HS-605C was connected, and the following silver ion sensor was connected to the other terminal. Here, the reference electrode was a double junction type electrode by the method described in JP-A-57-197534, and a 1N aqueous solution of potassium nitrate was used as the junction liquid.

The silver ion sensor, in addition to the silver sulfide electrode according to the present invention,
As a comparative example, a metal silver electrode, a metal gold electrode, and a metal platinum electrode were used.

Next, the silver nitrate aqueous solution and the potassium bromide aqueous solution are mixed, and 1%
An emulsion containing 0.1 mol of silver bromide in 1000 cc of ossein gelatin aqueous solution was prepared.

The average grain size of silver bromide grains in the emulsion was adjusted to 1 μm, and the theoretical silver potential was adjusted to show OmV (pAg = 10) (theoretical silver potential was calculated from the solubility product).

This emulsion solution was kept warm at 40 ° C., and the pAg measurement system using the silver ion sensor described above was mounted therein, and the potential when 30 seconds had elapsed was read. Subsequently, the silver ion sensor was taken out, thoroughly washed with distilled water at 40 ° C., and the water was wiped off with a tissue paper for chemical experiments.

The average value and standard deviation were determined from the values when the above operation was repeated 30 times and are shown in Table 1.

As is clear from the results shown in Table 1, the ^{recirculation} accuracy of the measurement system using the silver sulfide silver ion sensor, which is the method of the present invention, in silver halide emulsions having a silver ion concentration of 10 ^-10 mol / degree is It can be seen that it is superior to the comparative silver ion sensor.

Example 2 The same silver ion measurement control system of the present invention and comparative example as used in Example 1 was used, and the pH measurement control system was the same as that used for the HM-20E pH meter in the silver ion measurement control system. A silver halide emulsion was prepared as follows by using the comparative electrode of No. 1 and connecting HGS-2005 manufactured by Toa Denpa Kogyo as a pH sensor.

For the production of the silver halide emulsion, the following four kinds of solutions were prepared and used to prepare a monodisperse silver iodobromide emulsion having an AgI content of 40 mol%.

Solution A Solution B Solution C Silver nitrate 1 molar aqueous solution 800ml Solution D 1N nitric acid aqueous solution Solution A is stirred at 60 ° C, pAg measurement control system (the above silver ion sensors and double junction HS-605C) and pH.
Measurement control system (HGS-2005 and double junction HS
The potential and pH were measured by immersing -605C), the pAg value was adjusted to 3.0 (+404 mV) using a silver nitrate solution, and the pH value was adjusted to 2.0 using nitric acid.

While controlling the flow rates of solution B and solution D so that pAg and pH maintain these values, solution B and solution C were applied to solution A by the double jet method.
Was added. The solution C was added at a constant rate of 0.5 ml / min for 6 minutes from the start of the addition, and then linearly increased at a rate of 0.385 ml / min for 10 minutes. Needed.

When the silver halide grains prepared as described above were examined by an electron micrograph, a monodisperse emulsion having a [111] plane crystal habit was obtained.

The average grain size of the obtained silver halide grains is C
It was determined by the centrifugal sedimentation method with APA500.

For the evaluation of monodispersity, the standard deviation was obtained from the particle size distribution graph output from CAPA500, and the value obtained by dividing the standard deviation was used as the evaluation value of monodispersity.

Table 2 shows the results of the above-described operations from the production of the silver halide emulsion to the characteristic test being tried three times each.

As is clear from the results shown in Table 2, both the average particle size and the monodispersity of silver halide grains prepared using the silver ion sensor for silver sulfide, which is the method of the present invention, are reproducible. It can be seen that the monodispersity has excellent reproducibility as compared with the comparative example.

Example 3 Using the same silver ion measurement control system and pH measurement control system as used in Example 2, and using the following five types of solutions, Ag was used.
A cubic silver iodobromide emulsion having an I content of 2 mol% was prepared.

Solution E Solution F Solution G Equivalent + 2% silver nitrate solution containing 5% ammonia 800 ml Solution H 56% acetic acid aqueous solution 300 ml Solution I 40% potassium bromide solution 100 ml Solution E was stirred at 60 ° C. and the pAg measurement control system used in Example 2, Immerse the electrode of the pH measurement control system to pAg 9.0 (+42 mV), pH
Was adjusted to 9.0. Solution F and solution G were added by the double jet method at a speed at which new particles were not generated while controlling the flow rates of solution H and solution I to maintain this value. The time required to complete the addition was 54 minutes.

After the addition was completed, Solution H and Solution I were added to adjust the pH to 6.0 and pAg to 10.
In accordance with 0, washing and desalting were performed by the following operations.
158 ml and 142 ml of a 5% aqueous solution of Demol N manufactured by Kao Atlas and a 20% aqueous solution of magnesium sulfate as precipitants, respectively.
In addition, the precipitate was allowed to settle, and the supernatant was decanted.
Distilled water 2 at ℃ was added and dispersed again. After 90 ml of 20% magnesium sulfate was added again and the mixture was left to stand to precipitate the precipitate, the supernatant was decanted again. To this precipitate, 200 ml of an aqueous solution containing 21 g of gelatin was added, and distilled water was added until the total amount became 638 ml, followed by stirring for 20 minutes at 40 ° C. to disperse. After that, pAg was 8.55 and pH was 5.8 with the electrode used during manufacturing.
Readjusted to.

When the silver halide emulsion grains prepared as described above were examined by the same method as in Example 2, it was a monodisperse emulsion having a [100] crystal habit. Further, the results of average particle size and monodispersity were determined in the same manner as in Example 2, and the results are shown in Table 3.

As is clear from the results in Table 3, both the average grain size and the monodispersity of silver halide grains prepared using the silver ion sensor for silver sulfide, which is the method of the present invention, are reproducible. It can be seen that the monodispersity has excellent reproducibility as compared with the comparative example.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sadayuki Miyazawa 1 Sakura-cho, Hino-shi, Tokyo Konishi Roku Photo Industrial Co., Ltd. (56) Reference JP 53-137096 (JP, A) JP 54- 24012 (JP, A) JP-A-57-197534 (JP, A)

Claims (1)

[Claims] 1. A method for producing a silver halide emulsion, which is performed while controlling silver ions in the emulsion, wherein a silver sulfide electrode is used as a sensor for detecting silver ions.