JP2700679B2 - Method for producing silver halide grains - Google Patents

Description

The present invention relates to a method for producing silver halide grains. More specifically, the present invention relates to a method for producing silver halide grains in which the halide composition in each silver halide crystal is completely uniform and there is no halide distribution between grains.

[Conventional technology]

The formation of silver halide grains consists of two main processes, nucleation and crystal growth. James (THJame
s) The Theory of the Photographic Process, 4th Edition (Macmillan, 1977) states, "Nucleation is the process by which a completely new crystal is formed and the number of crystals increases rapidly. Growth is the addition of a new layer to an existing crystal and, in addition to the nucleation and crystal growth described above, there are two further steps under the conditions of photographic emulsion grain formation: Ostwald ripening and Ostwald ripening is likely to occur when the particle size distribution is broad at relatively high temperatures and in the presence of solvents. Recrystallization is a process that changes the crystal composition. " In other words, in the formation of silver halide grains, nuclei are formed in the initial stage, and in the subsequent crystal growth, growth occurs only in the existing nuclei, so that the number of grains during the growth process does not increase.

In general, silver halide grains are produced by reacting an aqueous silver salt solution with an aqueous halide salt solution in an aqueous colloid solution in a reaction vessel. A protective colloid such as gelatin and an aqueous solution of a halogen salt are placed in a reaction vessel, and a single jet method in which an aqueous solution of a silver salt is added thereto for a certain period of time with stirring, or an aqueous solution of gelatin is placed in a reaction vessel, and the aqueous solution of a halogen salt and silver are added. A double jet method in which a salt aqueous solution is added for a certain period of time is known. Comparing the two, the double jet method yielded silver halide grains with a narrower grain size distribution, and with the growth of the grains,
The halide composition can be freely changed.

It is known that the nucleation of silver halide grains varies greatly depending on the silver ion (halogen ion) concentration in the reaction solution, the concentration of the silver halide solvent, the degree of supersaturation, the temperature, and the like. In particular, the non-uniform silver ion or halogen ion concentration created by the silver salt aqueous solution and the halogen salt aqueous solution added to the reaction vessel causes a supersaturation and solubility distribution in the reaction vessel depending on the respective concentrations. The nucleation rates differ and cause inhomogeneities in the resulting silver halide crystal nuclei.

For this purpose, in order to make the silver ion or halogen ion concentration in the reaction vessel uniform, it is necessary to rapidly and uniformly mix the silver salt aqueous solution and the halogen salt aqueous solution to be supplied into the colloid aqueous solution to cause a reaction. In the conventional method of adding an aqueous solution of a halogen salt and an aqueous solution of a silver salt to the surface of an aqueous colloid solution in a reaction vessel, a portion having a high concentration of halogen ions and silver ions is generated in the vicinity of the position where each reaction solution is added, and uniform It has been difficult to produce silver halide grains. As a method for improving the local density, techniques disclosed in U.S. Pat. No. 3,415,650, British Patent No. 13,234,64, and U.S. Pat. No. 3,692,283 are known. In these methods, a reaction vessel filled with an aqueous colloid solution is provided with a hollow rotating mixer having a slit in the wall of a medium-thick cylinder (the interior is filled with an aqueous colloid solution, and more preferably, the mixer is vertically moved by a disk. Is provided so that the rotation axis thereof is vertical, and an aqueous halide solution and an aqueous silver salt solution are supplied from the upper and lower open ends into a mixer rotating at a high speed through a supply pipe. The mixture is rapidly mixed and reacted (if there are upper and lower separation disks, the aqueous halide solution and the aqueous silver salt solution supplied to the upper and lower two chambers are diluted by the aqueous colloid solution filled in each chamber, and the outlet slit of the mixer is used. The mixture is rapidly mixed and reacted in the vicinity), and the silver halide grains generated by the centrifugal force generated by the rotation of the mixer are discharged into the aqueous colloid solution in the reaction vessel and halogenated. It is a method in which generate a.

On the other hand, Japanese Patent Publication No. 55-10545 discloses a technique in which the local density is improved to prevent uneven growth. According to this method, a halogen salt aqueous solution and a silver salt aqueous solution are separately supplied through a supply pipe from a lower end of a mixer filled with a colloid aqueous solution into a reaction vessel filled with the colloid aqueous solution. Supply to
The reaction solution is rapidly stirred and mixed by a lower stirring blade (turbine blade) provided in a mixer to grow silver halide, and immediately grown by the stirring blade provided above the stirring blade. This is a technique for discharging the silver halide grains into the aqueous colloid solution in the reaction vessel from the opening of the upper mixer.

Japanese Patent Application Laid-Open No. 57-92523 discloses a production method which similarly attempts to improve the nonuniformity of the concentration. In this method, a halogen salt aqueous solution and a silver salt aqueous solution are separately supplied from an open lower end to a mixer filled with a colloid aqueous solution in a reaction vessel filled with a colloid aqueous solution. Both reaction solutions are diluted with the aqueous colloid solution, and the reaction solutions are rapidly stirred and mixed by a lower stirring blade provided in a mixer, and silver halide grains grown from an open portion above the mixer immediately Is discharged into a colloidal aqueous solution in a reaction vessel, and the reaction solution diluted with the colloidal aqueous solution is passed through the gap between the blades of the mixing blade without passing through the gap between the blades of the mixer. A method and apparatus for producing silver halide grains by passing through a gap formed on the outer side of the tip of the wing piece and rapidly reacting the two reaction solutions by shearing and mixing in the gap. It has been disclosed.

However, although the production method and apparatus described so far can substantially eliminate the nonuniformity of the local concentration of silver ions and halogen ions in the reaction vessel, this concentration still remains in the mixer. Inhomogeneity exists, and in particular, there is a considerably large concentration distribution near the nozzle for supplying the aqueous silver salt solution and the aqueous halogen salt solution, and at the lower portion and the stirring portion of the stirring blade. Furthermore, the silver halide grains supplied to the mixer together with the protective colloid pass through places having such a non-uniform concentration distribution, and most importantly, the silver halide grains rapidly grow up. In other words, in these manufacturing methods and apparatuses, since the concentration distribution exists in the mixer and the grain growth occurs rapidly in the mixer, nucleation and crystal growth are uniformly performed on the silver halide without the concentration distribution. The purpose of exercising has not been reached.

In order to eliminate the non-uniform distribution of silver ion and halogen ion concentration due to more complete mixing, the reaction vessel and the mixer were made independent, and the silver salt aqueous solution and the halogen salt aqueous solution were supplied to the mixer and rapidly mixed. Attempts have been made to form silver halide grains. For example, JP
JP-A-37414 and JP-B-48-21045 disclose that a protective colloid aqueous solution (including silver halide particles) in a reaction vessel is circulated from the bottom of the reaction vessel by a pump, and a mixer is provided in the middle of the circulation system. There is disclosed a production method and apparatus in which a silver salt aqueous solution and a halogen aqueous solution are supplied to the mixer, and the two aqueous solutions are rapidly mixed by the mixer to form silver halide grains. Also, US Pat.
A method is disclosed in which a protective colloid aqueous solution (including silver halide particles) in a reaction vessel is circulated from the bottom of the reaction vessel by a pump, and a halogen salt aqueous solution and a silver salt aqueous solution are injected into the circulation system by a pump. . JP-A-53-4739
In JP-A-7, a protective colloid aqueous solution (including a silver halide emulsion) in a reaction vessel is circulated from a reaction vessel by a pump, and an alkali metal halide aqueous solution is first injected into the circulation system until the solution becomes uniform. After spreading it,
There is disclosed a production method and apparatus characterized in that a silver salt aqueous solution is injected into this system and mixed to form silver halide grains.

[Problems to be solved by the invention]

However, with these methods, the flow rate of the aqueous solution in the reaction vessel flowing into the circulation system and the stirring efficiency of the mixer can be independently changed, and the particles can be formed under a more uniform concentration distribution condition. In the end, the silver halide crystals sent from the reaction vessel together with the protective colloid aqueous solution will grow rapidly at the injection port of the silver salt aqueous solution and the halogen salt aqueous solution. Therefore, it is theoretically impossible to eliminate the concentration distribution in the vicinity of the mixing portion or the injection port as described above, that is, the purpose of uniformly forming silver halide without the concentration distribution could not be achieved. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide nucleation and / or crystal growth of silver halide grains in a non-uniform field of concentration (silver ions and halogen ions) possessed by conventional manufacturing methods and equipment, and thereby non-uniform emulsion grains ( Another object of the present invention is to solve the problem of obtaining the grain size, crystal habit, distribution of halogen between grains and within grains, and distribution of reduced silver nuclei between grains and within grains.

The present applicant previously provided a mixer outside a reaction vessel for causing nucleation or crystal growth of silver halide grains in the course of silver halide grain formation for the purpose of the present invention,
An aqueous solution of a water-soluble silver salt and an aqueous solution of a water-soluble halide are supplied to and mixed with the mixer to form silver halide fine particles, and the fine particles are immediately supplied into a reaction vessel or a reaction vessel having a protective colloid aqueous solution, "Method for effecting the formation of silver halide grains" (Japanese Patent Application No. 63-195778)
) And "Method for causing crystal growth of silver halide grains" (Japanese Patent Application No. 63-7581). However, in these methods, when performing the reaction in a mixer for forming fine particles, it is important to perform the reaction while diluting with water or an aqueous solution of protective colloid. It was not possible to increase it, and in this state, the yield per charged unit was low, and this measure was required. The present invention relates to improvements of those inventions.

[Means and actions for solving the problem]

That is, the objects of the present invention are as follows: (1) A mixer is provided outside a reaction vessel for causing nucleation and / or crystal growth of silver halide grains, and an aqueous solution of a water-soluble silver salt and a water-soluble halide are provided in the outer mixer. And controlling the flow rate of the aqueous solution of, and mixing while controlling the rotation speed of the blades of the stirrer of the mixer to form silver halide fine particles, immediately supply the fine particles to a reaction vessel, and carry out the reaction. A method for performing nucleation and / or crystal growth of silver halide grains in a vessel, comprising mixing a liquid supplied from the mixer and a liquid extracted from the reaction vessel between the mixer and the reaction vessel, A method for producing silver halide grains, comprising removing water and a part of a water-soluble compound from the mixed solution, and supplying the mixture to a reaction vessel.

(2) The liquid from which a part of the water and the water-soluble compound is removed is not a mixed liquid but a liquid extracted from a reaction vessel before being mixed with a supply liquid from a mixer. The method for producing silver halide grains according to 1).

Achieved by

That is, in the present invention, in order to increase the growth rate of the fine particles added to the reaction vessel, the liquid supplied from the mixer to the reaction vessel is concentrated so as to shorten the distance between the particles in the reaction vessel.
Alternatively, in order to efficiently perform the concentration, the liquid in the reaction vessel is circulated, and water and water-soluble components provided on the way are removed by an ultrafiltration device or a semipermeable membrane device. In order to efficiently increase the removal rate, control was performed by detecting the internal pressure of the removal device or the removal flow rate with a control valve provided after the removal device.

The nucleus in the present invention refers to a grain in a process in which the number of silver halide crystals fluctuates during the formation of emulsion grains as described above, and is exclusively used without changing the number of silver halide crystals. A process in which growth only occurs in the nucleus is referred to as a particle that only grows.

During the nucleation process, the generation of new nuclei or the disappearance of existing nuclei and the growth of nuclei occur simultaneously.

When performing nucleation and / or crystal growth according to the present invention, it is important that no silver salt aqueous solution and halogen salt aqueous solution are added to the reaction vessel at all, and the protective colloid aqueous solution (silver halide particles) in the reaction vessel is further added. ) To the mixer is not performed at all. Thus, the present method is completely different from the conventional methods and is a novel and innovative method for obtaining uniform silver halide grains.

Next, FIGS. 1 and 2 show a system diagram of the method for producing silver halide grains according to the present invention.

In FIG. 1 and FIG. 2, first, the reaction vessel 1 contains a protective colloid aqueous solution 2. The aqueous protective colloid solution is stirred and mixed by a propeller 3 attached to a rotating shaft. A silver salt aqueous solution, a halogen salt aqueous solution, and a protective colloid aqueous solution are introduced into a mixer 7 outside the reaction vessel 1 in addition systems 4, 5, and 6, respectively. At this time, the aqueous solution of the water-soluble silver salt and the aqueous solution of the water-soluble halide may be supplied to the mixer 7 after being diluted with the aqueous protective colloid solution 6 in advance. The solutions are rapidly and vigorously mixed in a mixer and immediately introduced into reaction vessel 1 by introduction system 8 into the reaction vessel.
To be introduced. On the way, in FIG. 1, the liquid supplied from the mixer 7 and the liquid extracted from the reaction vessel 1 by the pump 20 are mixed by the mixer 21 and then water and a part of the water-soluble compound are removed from the mixed liquid. Reaction vessel 1 after passing through means 12
Or the liquid from the reaction vessel 1 drawn by the pump 20 as shown in FIG. 2 is passed through a means 12 for removing water and a part of the water-soluble compound, and then the liquid supplied from the mixer 7 And mixed by the mixer 21 and supplied to the reaction vessel. At this time, for example, an ultrafiltration module or the like or a semipermeable membrane is used as the means 12 for removing water and the water-soluble compound. In order to control the removal efficiency, the internal pressure in the apparatus is detected by a pressure gauge 18 or the flow rate to be removed is detected by a flow meter 19, thereby enabling a control valve 20 for a flow rate control which enables removal of a predetermined amount.
To control the removal rate.

FIG. 3 shows details of one embodiment of the mixer 7. The mixer 7 has a reaction chamber 10 therein.
The stirring blade 9 attached to the rotating shaft 11 is provided in the inside. A silver salt aqueous solution, a halogen salt aqueous solution, and a protective colloid aqueous solution are added to the reaction chamber 10 through three inlets (4, 5, the other inlet is omitted from the drawing).
Rotate the rotating shaft at high speed (1000 rpm or more, preferably 2000 rpm or more, more preferably 3000 rpm or more)
As a result, the solution containing extremely fine particles generated by rapid and intense mixing is immediately introduced into the reaction vessel 1 from the introduction system 8 into the reaction vessel.

At this time, the silver salt aqueous solution, the halogen salt aqueous solution, and the protective colloid aqueous solution are supplied from the respective preparation tanks, 14, 15, and 16 through the flow meters 13a, 13b, and 13c, respectively.
It is sent to the mixer 7 by 7a, 17b, 17c.

The very fine particles produced by the reaction in the mixer 7 are mixed with the reflux from the reaction vessel 1 while being introduced into the reaction vessel 1, and a part of the water and the water-soluble compound in the mixture is mixed. Is removed before or after mixing, concentrated, and supplied to the reaction vessel 1. Since the particle size is fine and concentrated, the fine particles easily dissolve and become silver ions and halogen ions again, causing uniform nucleation and / or crystal growth. The halide composition of the extremely fine grains is the same as the halide composition of the target silver halide grains. The ultrafine particles introduced into the reaction vessel 1 are dispersed in the reaction vessel 1 by stirring in the reaction vessel, and halogen ions and silver ions having a target halide composition are released from the individual fine particles. Here, the particles generated in the mixer 7 are extremely fine, the number of particles is very large, and silver ions and halogen ions (in the case of mixed crystal growth, the desired halogen Ionic composition) is released and occurs throughout the protective colloid in the reaction vessel 1, so that a completely uniform nucleation and / or crystal growth can occur. It is important that silver ions and halogen ions are never added to the reaction vessel 1 as an aqueous solution and that the protective colloid solution in the reaction vessel 1 is not circulated to the mixer 7. Here, the present invention has a surprising effect on nucleation and / or crystal growth of silver halide grains, which is completely different from the conventional method.

The fine particles formed in the mixer have a very high solubility due to the fine particle size, and when added to the reaction vessel, dissolve and become silver ions and halogen ions again, and the fine particles introduced into the reaction vessel are dissolved. Although it is deposited on a small part of the grains to form silver halide nucleus grains and promotes crystal growth, the fine grains have a high solubility, so that they are so-called Ostwald ripening among the fine grains, or are deposited on the grains in the reaction vessel to promote grain growth. At this time, the fine particles have high solubility, so that the fine particles are ripened with each other, and the particle size increases.

At that time, if the size of the fine particles introduced into the reaction vessel becomes large, the solubility decreases, the dissolution in the reaction vessel becomes slow, and if the nucleation rate is remarkably reduced, the fine particles are no longer dissolved. Can no longer do so,
Effective nucleation cannot be performed, and on the contrary, it itself becomes a nucleus and causes growth.

In the present invention, this problem has been solved by the following three techniques.

Immediately after forming the microparticles in the mixer, it is added to the reaction vessel.

As will be described later, conventionally, a fine particle emulsion is previously formed to obtain a fine particle emulsion, which is then re-dissolved, and the dissolved fine particle emulsion is used as a reaction vessel in which silver halide grains serving as nuclei are held and a silver halide solvent is present. Is known to cause particle formation. However, according to such a method, the extremely fine particles once formed undergo Ostwald ripening in the particle forming process, washing process, redispersing process, and re-dissolving process, and the particle size increases.

In the present invention, Ostwald ripening does not occur by providing a mixer very close to the reaction vessel and shortening the residence time of the additive liquid in the mixer, and thus by immediately adding the generated fine particles to the reaction vessel. I did it. Specifically, the residence time t of the liquid added to the mixer is expressed as follows.

v: Volume of the reaction chamber of the mixer (ml) a: Addition amount of silver nitrate solution (ml / min) b: Addition amount of halide salt solution (ml / min) c: Addition amount of protective colloid solution (ml / min) (However, in the case of the present invention, c includes the amount previously used for diluting a and b). In the production method of the present invention, t is 10 minutes or less, preferably 5 minutes or less, more preferably 1 minute. Below, more preferably
Less than 20 seconds. The fine particles thus obtained in the mixer are immediately added to the reaction vessel without increasing the particle size.

From the above viewpoint, the flow rate control of the aqueous solution of the water-soluble silver salt and the aqueous solution of the water-soluble halide of the present invention plays an important role. One of the features of the present invention lies in this point, and the a, b, c
Is to adjust the total flow rate with each of the addition amounts or the ratio of each other being constant.

 Strong and efficient stirring is performed in the mixer.

James (THJames) The Theory of the
The photographic process, p. 93, states that another form, coalescenc
e). In coalescence ripening, previously distant crystals come into direct contact and adhesion to form larger crystals, causing a sudden change in particle size. Both Ostwald ripening occurs not only after the end of the deposition, but also during the deposition. The coalescence ripening described herein is likely to occur, especially when the particle size is very small, especially when the stirring is insufficient. In extreme cases, it can even produce coarse, massive particles. In the present invention, the second
As shown in the figure, since a closed mixer is used, the stirring blades of the reaction chamber can be rotated at a high rotation speed, which cannot be achieved with a conventional open-type reaction vessel.
When the stirring blade is rotated at a high rotation speed, the liquid is dislodged by the stretching force, and there is a problem of foaming, which is not practical. ) Powerful and efficient stirring and mixing can be performed, and the above-mentioned coalescence ripening can be prevented. As a result, fine particles having a very small particle size can be obtained. In the present invention, the rotation speed of the stirring blade is 1000 rpm or more, preferably 2000 rpm or more,
More preferably, it is 3000 rpm or more.

Therefore, the control of the rotation speed of the stirring blade of the mixer in the present invention plays an important role.

Injection of Protective Colloid Aqueous Solution into Mixer The aforementioned coalescence ripening can be significantly prevented by the protective colloid of silver halide fine grains. In the present invention, the following method can be considered for adding the aqueous protective colloid solution to the mixer.

a Inject the aqueous protective colloid solution into the mixer alone The protective colloid concentration is 0.2% by weight, preferably 0.5% by weight
Preferably, the flow rate is at least 20%, preferably at least 50%, more preferably 100% or more of the sum of the flow rates of the silver nitrate solution and the aqueous solution of the halogen salt. This method was adopted in the present invention.

b. Protective colloid is added to the halogen salt aqueous solution.

The protective colloid concentration is 0.2% by weight, preferably 0.5% by weight or more.

c Include a protective colloid in the silver nitrate aqueous solution.

The protective colloid concentration is at least 0.2% by weight, preferably at least 0.5% by weight. When gelatin is used, it is better to mix the silver nitrate solution and the protective colloid solution immediately before use, since gelatin silver is formed from silver ions and gelatin, and photolysis and thermal decomposition produce silver colloids.

The above methods a to c may be used alone or in combination with a and b, and a and c, respectively.
At the same time, a, b, and c may be used. As the protective colloid used in the present invention, gelatin is usually used, but other hydrophilic colloids can also be used. Specifically, Research Disclosure, Vol. 176, No. 17643 (1.
(December 978), section IX.

Thus, the particle size obtained by the technique (1) can be confirmed by placing the particles on a mesh and using a transmission electron microscope as it is, and the magnification is preferably 20,000 to 40,000. The size of the fine particles of the present invention is 0.06 μm or less, preferably 0.03 μm or less, more preferably 0.01 μm or less.

U.S. Pat.No. 2,146,938 discloses that coarse particles that do not adsorb adsorbed materials and fine particles that do not adsorb adsorbed materials are mixed, or the fine particle emulsion is slowly added to the coarse particle emulsion to grow the coarse particle emulsion. A method of doing so is disclosed.
Here, the fine grain emulsion is prepared by adding a previously prepared emulsion, which is completely different from the present method.

JP-A-57-23932 discloses a method in which a fine grain emulsion prepared in the presence of a growth inhibitor is washed with water, dispersed, redissolved and added to emulsion grains to be grown to grow the grains. It has been disclosed. However, this method is completely different from the method of the present invention as described above.

The James of the Theory of the Photographic Process, 4th Edition, refers to Lippmann Emulsion as fine grains and states that its average size is 0.05 μm. Although it is possible to obtain fine particles having a particle size of 0.05 μm or less, even if it is obtained, the particle size is unstable and easily increased by Ostwald ripening. JP
When the adsorbate is adsorbed as in the method of 57-23932, this Ostwald ripening can be prevented to some extent.
The dissolution rate of the fine particles is also reduced, which is contrary to the intention of the present invention.

U.S. Pat.No. 3,317,322 and U.S. Pat.No. 3,206,313 each have an average grain size of at least 0.8 .mu.m and a chemically sensitized core silver halide grain emulsion having an average grain size of 0.4 .mu.m or less. A method of forming a shell by mixing and ripening a silver halide grain emulsion that has not been chemically sensitized is disclosed. However, this method is also completely different from the method of the present invention because a fine grain emulsion uses a previously prepared emulsion, and the two emulsions are mixed and ripened.

JP-A-62-99751 discloses an average diameter range of 0.4 to 0.55.
μm and an aspect ratio of 8 or more.
The publication discloses a photographic element containing silver bromide and silver iodobromide tabular silver halide grains having an average diameter range of 0.2 to 0.55 μm. During growth, an aqueous solution of silver sulfate and an aqueous solution of potassium bromide are added to the reactor by double jet in the presence of a protective colloid (bone gelatin), and the iodine is a silver iodide (AgI) emulsion (particle size: about 0.05 μm, bone gelatin 40 g / (Ag mol) is simultaneously added and supplied to grow silver iodobromide tabular grains. In this method, a silver nitrate aqueous solution and a potassium bromide aqueous solution are added to a reaction vessel simultaneously with the addition of silver iodide fine particles, which is completely different from the method of the present invention.

In JP-A-58-113927 (pp207),
"The silver, bromide and iodide salts can be introduced initially or during the growth stage in the form of fine silver halides which are suspended in a dispersing medium, ie silver bromide, silver iodide and / or iodine odor. Silver halide particles can be introduced ".

However, this description is merely a general description that a fine grain emulsion is used for silver halide formation, and does not indicate the method and system disclosed in the present invention.

JP-A-62-124500 describes an example in which host particles in a reaction vessel are grown using extremely fine particles prepared in advance, but this method also uses a method in which a fine particle emulsion prepared in advance is added. This is completely different from the method of the present invention.

According to the conventional methods described so far, fine grains having a small grain size cannot be obtained since a fine grain emulsion is prepared in advance and the emulsion is dissolved and used. Therefore, these relatively large-sized fine particles cannot be dissolved rapidly in the reaction vessel, and it takes a very long time to complete the dissolution completely, or a large amount of silver halide solvent has to be used. Will not get. In such a situation, very low supersaturation nucleation will occur for the particles to be grown in the vessel, resulting in a significant spread of the nucleus and / or crystal particle size distribution. Therefore, the size distribution of the projected particles is widened, the photographic gradation is lowered, the chemical sensitization is non-uniform (large-sized particles and small-sized particles cannot be optimally chemically sensitized simultaneously), and the fog is increased. , Resulting in deterioration of performance such as deterioration of graininess. Further, in the conventional method, there are several steps of grain formation, washing, dispersion, cooling, storage, and re-dissolution, the production cost is high, and the addition of the emulsion requires
There are many restrictions on the addition system as compared with other solutions. These problems are solved by the method of the present invention. That is, according to the method of the present invention, since very fine particles are introduced into the reaction vessel, the solubility of the fine particles is high, and thus the dissolution rate is high, and the particles to be grown in the reaction vessel are subjected to high supersaturation conditions. Nucleation and / or crystal growth. Therefore, the size distribution of the nuclei and / or crystal grains thus formed does not spread. Further, since the fine particles generated by the mixer are added to the reaction vessel as it is, there is no problem in the production cost.

In the method of the present invention, if a silver halide solvent is added to the reaction vessel and used, a higher dissolution rate of fine particles and a higher nucleation rate and / or growth rate of grains in the reaction vessel can be obtained. .

Examples of the silver halide solvent include water-soluble bromide, water-soluble chloride, thiocyanate, ammonia, thioether, and thioureas.

For example, thiocyanates (eg, US Pat. No. 2,222,264)
No. 2,448,534 and 3,332,069), ammonia, thioether compounds (for example, US Pat. No. 327115)
No. 7, No. 3574628, No. 3704130, No. 4297439,
No. 4,276,345, nuclear specification, etc.), thione compounds (for example, JP-A-53-144319, JP-A-53-82408, JP-A-55-77737, etc.), and amine compounds (for example, JP-A-54-100717) ) Thiourea derivatives (for example, JP-A-55-2982)
Examples thereof include imidazoles (for example, JP-A-54-100717) and substituted mercaptotetrazole (for example, JP-A-57-202531).

According to the method of the present invention, the supply rates of silver ions and halide ions to the mixer can be freely controlled.
A constant supply rate may be used, but it is preferable to increase the addition rate. The method is JP-B-48-26890, 52-1
No. 6264 is described in each publication. Further, according to the method of the present invention, the halogen composition during growth can be freely controlled, for example, in the case of silver iodobromide, to maintain a constant silver iodide content, or to continuously increase the silver iodide content, It is possible to reduce or at some point change the silver iodide content.

The temperature of the reaction in the mixer is preferably 60 ° C or lower, more preferably 50 ° C or lower, more preferably 40 ° C or lower.

At a reaction temperature of 35 ° C. or less, low-molecular-weight gelatin (average molecular weight of 30,000 or less) is preferably used because ordinary gelatin easily solidifies.

The low molecular weight gelatin used in the present invention can be usually prepared as follows. A commonly used gelatin having an average molecular weight of 100,000 is dissolved in water, and a gelatin-decomposing enzyme is added to gelatinize the gelatin molecules. See RJCox.Photographic Gelation II, Academic Pres
s, London, 1976, pages 233 to 251, and pages 335 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. In addition, low pH (pH
1-3) or heated under high pH (pH 10-12) atmosphere,
There is also a method of hydrolysis.

The temperature of the protective colloid in the reaction vessel is preferably 40 ° C. or higher, preferably 50 ° C. or higher, more preferably 60 ° C. or higher.

In the present invention, during the nucleation and / or the crystal growth, no silver salt aqueous solution and no halogen salt aqueous solution are added to the reaction vessel at all, but the pAg of the solution in the reaction vessel is adjusted prior to nucleation. , An aqueous solution of a halogen salt or an aqueous solution of a silver salt can be added. In order to adjust the pAg of the solution in the reaction vessel during nucleation, an aqueous solution of a halogen salt or an aqueous solution of a silver salt can be added (temporarily or continuously). If necessary, an aqueous solution of a halogen salt or an aqueous solution of a silver salt can be added by a so-called pAg control double jet to keep the pAg in the reaction vessel constant.

The control method of the present invention is very effective in producing various emulsions.

In the nucleation and / or crystal growth of mixed crystal grains of silver iodobromide, silver iodobromide, and silver chlorobromide of silver iodochloride, it is preferable to use conventional manufacturing methods. Microscopic non-uniformity of the halides occurs, for example, by adding a manufacturing solution to obtain a uniform halide distribution, that is, by adding an aqueous halide solution and an aqueous silver salt solution having a fixed halide composition to the reactor, thereby forming nuclei and / or crystals. Growth cannot be avoided. This microscopic non-uniform distribution of halide can be easily confirmed by observing a transmission image of silver halide grains using a transmission electron microscope.

For example, Hamilton Photographic Science and Engineering 11
Volume, 1967 p.57 and Takeshi Shiozawa The Photographic Society of Japan 35 35 4 19
72 can be observed by a direct method using a transmission electron microscope at low temperature described on page 213. That is,
Place the silver halide grains taken out under safe light so that the emulsion grains do not print out, place them on a mesh for electron microscope observation, and cool the sample with liquid nitrogen or liquid heliutem to prevent damage by electron beams (such as printouts). Observation is performed by a transmission method in a state where the state is set.

Here, the higher the accelerating voltage of the electron microscope is, the clearer the transmission image can be obtained. However, 200 Kvolts is preferable up to a particle thickness of 0.25 μm, and 1000 Kvolts is preferable for the particle thickness more than 0.25 μm. The higher the accelerating voltage, the greater the damage of the particles by the irradiation electron beam. Therefore, it is desirable to cool the sample with liquid helium rather than liquid nitrogen.

The photographing magnification can be appropriately changed depending on the particle size of the sample, but is 20,000 to 40,000.

In a silver halide composed of a single halide, there is naturally no possibility of uneven distribution of the halide, so that a transmission electron micrograph can only obtain a flat image, while a mixed crystal composed of a plurality of halides can not be obtained. Very detailed annual ring-shaped stripes are observed.

For example, when a transmission electron micrograph of silver iodobromide tabular grains is taken, very fine annual ring-shaped stripes are observed in the silver iodobromide phase. Here, the tabular grains have silver bromide tabular grains as a core and a shell of silver iodobromide of 10 mol% of silver iodide formed outside the core.
Its structure can be clearly seen in this transmission electron micrograph. In other words, the core part is silver bromide and is naturally uniform, so that only a uniform flat image can be obtained.On the other hand, the silver iodobromide phase has very detailed annual ring-shaped stripes. You can check.

It can be seen that the spacing of the stripes is very fine, on the order of 100 ° or less, indicating very microscopic non-uniformity.

Various ways can reveal this very fine stripe pattern indicating non-uniform halide distribution, but more directly, annealing the grains under conditions that allow iodide ions to move through the silver halide crystals. (Annealing) (for example, at 250 ° C. for 3 hours), this stripe pattern disappears completely, so it can be clearly concluded.

No annual ring-shaped stripes are observed in the tabular grains prepared according to the method of the present invention, and silver halide grains having a completely uniform silver iodide distribution are obtained. The position of the phase containing silver iodide in the grains may be at the center of the silver halide grains, may extend over the grains, or may be at the outside. The phase in which silver iodide is present may be one or more.

Regarding these, Japanese Patent Application Nos. 63-7851 and 63-8752,
The details are described in JP-A-63-7785. Although these inventions relate to grain growth, the same is true for their effect on nucleation.

The silver iodide phase or the silver iodochlorobromide phase contained in the emulsion grains produced by using the control method of the present invention has a silver iodide content of 2 to 45 mol%, preferably 5 to 35 mol%. is there. The total silver iodide content is 2 mol% or more, but more effective is 5 mol% or more. It is more preferably at least 7 mol%, particularly preferably at least 12 mol%.

The method of the present invention is also useful in the production of silver chlorobromide grains, and silver chlorobromide grains having a completely uniform distribution of silver bromide (silver chloride) can be obtained. The silver chloride content is at least 10 mol%, preferably at least 20 mol%.

Further, the method of the present invention is very effective also in the production of pure silver bromide and pure silver chloride. According to the conventional manufacturing method, the presence of a local distribution of silver ions and halide ions in the reaction vessel is inevitable, and the silver halide grains in the reaction vessel pass through such locally nonuniform portions. This leads to a different environment from other uniform parts, which, of course, leads to non-uniform growth.
For example, reduced silver or fogged silver is generated in a high concentration portion of silver ions. Therefore, in silver bromide and silver chloride, there is certainly no non-uniform distribution of halide, but another non-uniformity as described above occurs. This problem can be completely solved by the method of the present invention. The silver halide grains of the present invention can of course be used for surface latent image type emulsions, but can also be used for internal latent image forming type or direct reversal emulsions by this method.

In general, internal latent image forming silver halide grains have advantages over surface latent image forming grains in the following respects.

A space charge layer is formed on the silver halide crystal grains, and electrons generated by light absorption are directed to the inside of the grains, and holes are directed to the surface. Therefore, if a latent image site (electron trap site), that is, a photosensitive nucleus is provided inside the particle, recombination is prevented, a latent image can be formed with high efficiency, and high quantum sensitivity can be realized.

Since the photosensitive nucleus is present inside the particles, it is not affected by moisture or enzymes, and has excellent preservability.Since the latent image formed by exposure also exists inside,
The latent image stability is very high without being affected by moisture or oxygen.

When the sensitizing dye is adsorbed on the grain surface and the emulsion is color sensitized, the light absorption site (the surface sensitizing dye) and the latent sensitizing site (the inner photosensitive nucleus) are separated, so that the dye hole The recombination of electrons and electrons is prevented, so that inherent desensitization in so-called color sensitization does not occur, and high color sensitization sensitivity can be realized.

As described above, the internal latent enhancement type particles have advantages as compared with the surface latent enhancement type particles, but have difficulty in incorporating the photosensitive nucleus into the inside of the particles. For the purpose of incorporation into the grains of the photosensitive nucleus, the grains to be the core are formed once, and then subjected to chemical sensitization to form the photosensitive nucleus on the surface of the core. Thereafter, silver halide is deposited on the core to form a so-called shell. However, the photosensitive nuclei on the surface of the core particles obtained by chemical sensitization of the core are liable to change during shell formation and often convert to internal fog. One of the causes is that shell formation on the core is damaged when the density (silver ion concentration, halogen ion concentration) is uneven as in the past, and the photosensitive nucleus is considered to be easily changed to a fog nucleus. Can be By using the method of the present invention, this problem can be solved and an internal latent image forming silver halide emulsion having very little internal fog can be obtained. As the internal latent image forming silver halide grains, normal crystals and tabular grains are preferable, and silver bromide, silver iodobromide and silver chlorobromide and silver chloroiodobromide having a silver chloride content of 30 mol% or less are preferable. However, preferred is silver iodobromide having a silver iodide content of 10 mol% or less.

In this case, the molar ratio of core / shell may be arbitrary, but is preferably 1/2 or less, more preferably 1/20 or more, and more preferably 1/3 to 1/1/2.
It is 10.

Metal ions can be doped inside instead of or in combination with the internal chemical sensitization nucleus. The doping position may be a core, a core / shell interface, or a shell.

As the metal dopant, cadmium salts, lead salts, thallium salts, erbium salts, bismuth salts, iridium salts, rhodium salts, or complex salts thereof are used. The metal ion is usually used in a proportion of at least 10 ^-6 mol per mol of silver halide.

The silver halide nucleus grains obtained according to the present invention are then grown to grow into silver halide grains having the desired size and halogen composition.

Particularly growing silver halide is a mixed crystal
In the case of silver iodobromide, silver iodobromochloride, silver chlorobromide, or silver iodochloride, it is preferable to grow grains by the method of the present invention following nucleation. If necessary,
It is also preferable to add a previously prepared fine grain emulsion to a reaction vessel for growth. Details of these methods are described in Japanese Patent Application Nos. 63-7851, 63-8752, and 63-7853. The silver halide grains thus obtained have a "perfectly uniform" halide distribution in both the nuclei and the growing phase of the grains, and have a very small grain size distribution.

The obtained completely uniform silver halide emulsion grains are not particularly limited, but are preferably at least 0.3 μm, more preferably at least 0.8 μm, particularly preferably at least 1.4 μm. The silver halide grains according to the present invention may have a regular crystal form (normal crystal grains) such as a hexahedron, an octahedron, a dodecahedron, a tetrahedron, a 24 tetrahedron, and a 40-octahedron. The particles may be irregular in crystalline form, such as spherical or potato-like, and may be variously shaped grains having one or more twin planes, particularly hexagonal tabular grains having two or three parallel twin planes. And triangular tabular twinned grains.

The silver halide photographic emulsion obtained according to the present invention is used, and there are no particular restrictions on other constitutions of the light-sensitive material, such as various additives of the light-sensitive material and a developing method.
No. 123042, No. 63-106745, No. 63-1000074, No. 63-10
Nos. 0445, 63-71838, 63-85547, Research Disclosure Magazine 176 items 17643 and 18
The description of item 7716 in volume 7 is helpful.

The locations of the above Research Disclosure Magazine (RD) are listed below.

[Example] Comparative Example-1 As in the conventional method, 5 L of a liquid (2% aqueous gelatin solution) in a reaction vessel was supplied to a mixer at a flow rate of 500 ml / min per minute.
A 1.2 mol silver nitrate aqueous solution and a potassium bromide aqueous solution were supplied to this mixer at a rate of 100 ml / min and mixed at 5000 rpm.
Further, the reaction product was introduced into an ultrafiltration device provided in the middle of the circulation path, water and water-soluble components were removed at an internal pressure of 1 kg / cm ² , and the other components were returned to the reaction vessel. . The addition in this state was performed for 10 minutes. Further, a propeller blade is provided in the reaction vessel, and stirring is performed.

Example 1 Using the apparatus shown in FIG. 2 of the present invention, 2 L of water was previously put into a reaction vessel, and the reaction vessel was returned to the reaction vessel through an ultrafiltration membrane at a flow rate of 500 ml / min. Circulates in the system. A mixer was provided in another system, and a 1.2 mol aqueous solution of silver nitrate, an aqueous solution of potassium bromide, and a 2% aqueous solution of gelatinant were used under the same recipe and conditions as in Comparative Example 1 at 500 rpm.
Was mixed at a rotation speed of. This addition was also performed for 10 minutes as described above. The reaction product is withdrawn from the reaction vessel, subjected to ultrafiltration, mixed with the liquid from the mixer, and returned to the reaction vessel. The reaction vessel was stirred under the same conditions as above.

Comparative Example 2 The same addition conditions as in Example 1 were used, except that ultrafiltration was not performed.

As an evaluation method for this comparison, the amount of dehydration in the ultrafiltration membrane and the size of the particles immediately after the mixer and after the crystal growth in the reaction vessel were evaluated. In addition, the sampling of the electron microscope evaluation was performed 1 minute and 9 minutes after the start of the addition using a sampling valve provided immediately after the mixer for the size evaluation immediately after the reaction. In order to evaluate the size after the addition, the reaction was carried out in a reaction vessel 20 ′ after the addition. The sample was rapidly cooled with liquid nitrogen to suppress growth, and evaluated by a cooling method direct electron microscope.
(20,000 times) The results are shown in Table 1.

As is clear from the above Table 1, the size of the fine particles immediately after the mixer was determined by comparing the liquid of the reaction vessel with the mixer of the present invention outside the reaction vessel without mixing the liquid of the reaction vessel into the mixer. Sample No. 1 was able to form extremely fine particles in the mixer as compared with Comparative Example-1 of the conventional method. This indicates that the crystal growth in the next reaction vessel can be made very uniform by the difference in the size distribution after the crystal growth.

Also, in the comparison between Comparative Example-2 and Example-1, the method of the present invention concentrated using an ultrafiltration membrane has a larger particle size after growth than Comparative Example-2 not using an ultrafiltration membrane. Value, and the size distribution hardly changes. That is, it indicates that crystal growth is promoted.

Furthermore, although not described in Table 1, the yield per unit of preparation in Example-1 was greatly increased by concentration of the preparation as compared with Comparative Example-2.

〔The invention's effect〕

As is clear from the results of the above Examples and the description in the specification, the method for producing silver halide grains of the present invention comprises the following steps: (1) By separating a reaction vessel for growing and a mixer for forming fine grains, Stable and uniform particle formation can always be performed.

(2) Since the liquid in the reaction vessel was concentrated by the ultrafiltration membrane, the yield per unit charged was improved.

(3) The particle size can be reduced by diluting the aqueous silver salt solution and the aqueous halogen salt solution in the mixing vessel. Therefore, this restriction can be eliminated, and fine particles can be formed more, thereby enabling uniform crystal growth.

(4) The liquid in the reaction vessel was concentrated and the mixture was instantaneously and uniformly mixed in the piping, so that the physical ripening time was shortened and uniform crystal growth was increased.

(5) The size distribution of silver halide could be narrowed.

Etc., which greatly contributed to quality improvement in the method for producing silver halide grains.

[Brief description of the drawings]

1 and 2 are system flow sheets of the method for producing silver halide grains of the present invention, and FIG. 3 is a cross-sectional view of one embodiment of the mixer used in the present invention. DESCRIPTION OF SYMBOLS 1 ... Reaction container 2 ... Protective colloid aqueous solution 3 ... Propeller 4 ... Addition system of silver salt aqueous solution 5 ... Addition system of halogen salt aqueous solution 6 ... Addition system of aqueous protective colloid solution 7 ... Mixer, 8 ... ... Introduction system to reaction vessel 9 ... Agitating blade, 10 ... Reaction chamber 11 ... Rotating shaft 12 ... Means for removing part of water and water-soluble compounds 13a, 13b, 13c ... Flow meter 14 ... Silver salt aqueous solution preparation tank 15… Halogen salt aqueous solution preparation tank 16… Protective colloid aqueous solution preparation tank 17a, 17b, 17c… Flow control pump 18… Pressure detector 19… Flow meter 20… Pump 21 …… Mixer 22 …… Control valve

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeharu Urabe 210 Nakanuma, Minamiashigara-shi, Kanagawa Fujisha Shin Film Co., Ltd. (56) References JP-A-62-138844 (JP, A) 59053 (JP, B2)

Claims (2)

(57) [Claims] 1. A mixer is provided outside a reaction vessel for causing nucleation and / or crystal growth of silver halide grains, and the external mixer controls flow rates of an aqueous solution of a water-soluble silver salt and an aqueous solution of a water-soluble halide. And mixing while controlling the number of revolutions of the blades of the stirrer of the mixer to form silver halide fine particles, immediately supply the fine particles to a reaction vessel, and in the reaction vessel, Nucleation of particles and / or
Or a method of performing crystal growth, after mixing the liquid supplied from the mixer and the liquid extracted from the reaction vessel between the mixer and the reaction vessel, water and a part of the water-soluble compound from the mixture And then supplying the reaction mixture to a reaction vessel. 2. The liquid for removing a part of water and a water-soluble compound is not a mixed liquid but a liquid extracted from a reaction vessel before being mixed with a supply liquid from a mixer. Item (1).