JPH11271904A - Manufacture of silver halide emulsion, silver halide emulsion and silver halide photographic sensitive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dissolve a problem in the conventional method of introducing dislocation lines to flat silver halide grains, and concreatly to provide the method for manufacturing the silver halide emulsion by introducing the dislocation lines in definite positions in a high density and extremely enhancing the uniformity in the grains. SOLUTION: The flat silver halide grains having principal (111) faces and an average silver bromide content of >=70 mol.% and an aspect ratio of >=2 and corresponding circle diameter of >=0.5 μm occupy >=90% of the projection areas of the total silver halide grains, and >=50 number % of these flat grains have the >=10 dislocation lines substantially on the fringe part of each grain. The silver halide emulsion is prepared by feeding a silver halide emulsion high in silver iodide content and having a multiple twin crystal content of <=1 number % prepared in the outer part of a reactor and feeding them into the reactor and adding to the basic silver halide grains.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a silver halide emulsion, a silver halide emulsion and a silver halide photographic light-sensitive material.
The present invention relates to a method for producing a silver halide emulsion having excellent pressure characteristics, a silver halide emulsion, and a silver halide photographic material.

[0002]

2. Description of the Related Art In recent years, demands for photographic silver halide emulsions have become increasingly severe, and higher requirements have been made with respect to sensitivity, graininess, pressure characteristics and the like. As a solution to these requirements, it is known in the art to introduce dislocation lines into tabular silver halide grains. JP-A-63-220238, JP-A-1-20
Nos. 1649 and 1-329231 and 8-1
No. 90164 discloses a technique for introducing dislocation lines into tabular silver halide grains, and discloses that a silver halide emulsion having improved sensitivity, graininess, fog, etc. can be obtained. . In these publications, as a method of forming a high silver iodide phase for introducing dislocation lines, an aqueous solution of potassium iodide, double jet addition of an aqueous solution of silver salt and an aqueous solution of iodide salt, and further a method of forming an iodide ion releasing agent are described. Use and the like are disclosed. However, the techniques disclosed in the above publications have insufficient densification and limited positions of dislocation lines, and insufficient uniformity between grains, and have not yet led to a sufficient improvement in the above various photographic properties.

Japanese Patent Application Laid-Open No. 4-182635 discloses a technique for forming dislocation lines near edges and / or corners of tabular silver halide grains using a silver iodide fine grain emulsion. The silver iodide fine grain emulsion used in the publication has no consideration for lowering the multiple twin ratio during the formation thereof, and therefore the problem when a fine grain emulsion having a high multiple twin ratio is added is completely eliminated. Not.

On the other hand, Japanese Patent Application Laid-Open No. 9-197587 discloses a technique in which a silver halide fine grain emulsion containing no multiple twin grains in which the number ratio of grains exceeds 1% is supplied to grow a crystal. . However, there is no specific description in this publication regarding formation of high-density and uniform dislocation lines between grains at limited positions using such a fine grain emulsion.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the problems which have been insufficient with the conventional method of introducing dislocation lines into tabular silver halide grains. An object of the present invention is to provide a method for producing a silver halide emulsion in which dislocation lines are introduced at a high density at a limited position and the uniformity between grains is remarkably improved.

[0006]

The above objects of the present invention have been attained by the following constitutions.

[0007] 1. A tabular silver halide grain having a (111) main plane, an average silver bromide content of 70 mol% or more, an aspect ratio of 2 or more, and an equivalent circle diameter of 0.5 μm or more has a total projected area. And at least 50% of the tabular silver halide grains have 10 or more dislocation lines localized only in the fringe portion. The multiple twin ratio prepared outside the reaction vessel having silver halide grains is 1
% Of a high silver iodide fine grain emulsion having a high silver iodide content of not more than 0.1% to a silver halide grain serving as a base.

[0008] 2. 2. The method for producing a silver halide emulsion according to 1, wherein the average grain size of the high silver iodide fine grain emulsion is 0.2 μm or less.

3. A dispersion medium, having a (111) main plane;
Tabular silver halide grains having an average silver bromide content of 70 mol% or more, an aspect ratio of 2 or more, and an equivalent circle diameter of 0.5 μm or more occupy 90% or more of the entire projected area. A silver halide emulsion containing tabular silver halide grains in which at least 50% of the number of silver halide grains are localized substantially in only the fringe portion and at least 10 dislocation lines; Silver halide grains having a multiple twin ratio of 1
% Silver halide grains having a high silver iodide-containing phase formed by supplying a high silver iodide fine grain emulsion of not more than 0.1% by weight.

[0010] 4. A silver halide photographic material having at least one silver halide emulsion layer on a support, characterized in that the silver halide emulsion layer contains the silver halide emulsion described in (3) above. Silver photographic photosensitive material.

Hereinafter, the present invention will be described in detail.

First, the tabular silver halide having dislocation lines of the present invention will be described.

In the tabular silver halide emulsion of the present invention, tabular silver halide grains having an equivalent circle diameter (ECD) of 0.5 μm or more and an aspect ratio of 2 or more account for 90% or more of the total projected area. Occupy. An ECD of 0.5 μm or more is preferable for introducing high-density dislocation lines into the fringe portion. The ECD is usually less than 10 μm, in most cases less than 5 μm, particularly preferably in the range of 0.7-4 μm. It is preferable that tabular silver halide grains having an aspect ratio of 2 or more occupy 90% or more of the total projected area in order to develop performance (sensitivity and the like) as tabular silver halide grains.

In the tabular silver halide emulsion of the present invention, when the average silver bromide content relative to the total silver halide is 70 mol% or more, there is no difference in the production method because the influence of the AgCl system does not appear. In addition, the average silver bromide content is more preferably 80 mol% or more, from the viewpoint of performance (sensitivity and the like). For example, silver iodobromide and silver iodochlorobromide are included. In the case of a photographic film, the tabular silver halide grains contain silver iodide in an amount of at least 0.1% based on the total silver halide.
It is preferable to contain 10 mol%, and 0.25 mol
% Or more and less than 10 mol%.

The tabular silver halide grains of the present invention are (11)
1) It has a main plane. Such tabular grains typically have a triangular or hexagonal major surface.

In the tabular silver halide emulsion of the present invention, the coefficient of variation of the equivalent circle diameter distribution is preferably 30% or less, more preferably 20% or less. Here, the coefficient of variation is a value obtained by multiplying the quotient obtained by dividing the standard deviation of the ECD of a particle by the average ECD by 100. In the present invention, a tabular emulsion excellent in monodispersity is referred to as having a coefficient of variation of a circle equivalent diameter distribution of tabular silver halide grains of 30% or less. It is presumed that a tabular emulsion having excellent monodispersity is likely to be uniformly sensitized between grains in a sensitization process after preparation of grains, and is preferable in photographic performance.

In the tabular silver halide emulsion of the present invention, grains in which 10 or more dislocation lines are localized substantially only in the fringe portion occupy 50% or more of the number of tabular silver halide grains. Is preferred. The present inventors have found that the pressure characteristics of tabular silver halide grains are remarkably improved by making the dislocation lines uniform within the grains and between the grains, more densely and highly localized in the fringe portion. I found it.

In the present invention, the dislocation line is, as described above,
Localized in the fringe of the particles and dense
Regarding the dislocation lines of silver halide crystals, (1) C.I. R. B
erry, J .; Appl. Phys. , 27,636
(1956), (2) C.I. R. Berry, D.M. C. S
kilman. J. Appl. Phys. , 35,21
65 (1964); F. Hamilton,
Photo. Sci. Eng. , 11, 57 (196)
7), (4) T.P. Shiozawa, J .; Soc. Ph
ot. Sci. Jap. , 34, 16 (1971),
(5) T. Shiozawa, J .; Soc. Photo.
Sci. Jap. , 35, 213 (1972), which can be analyzed by an X-ray diffraction method or a direct observation method using a low-temperature transmission electron microscope. The fringe portion referred to in the present invention refers to the outer periphery of tabular grains. Specifically, in the distribution of silver iodide from the sides to the center of the tabular grains, the silver iodide content at a certain point for the first time when viewed from the sides. Means outside the point where the average silver iodide content of the whole grain exceeds or falls below.

When directly observing dislocation lines using a transmission electron microscope, the silver halide grains taken out of the emulsion are carefully screened so as not to apply enough pressure to generate the dislocation lines. Then, observation is performed by a transmission method in a state where the sample is cooled so as to prevent damage (for example, printout) by an electron beam. In this case, the thicker the particle, the more difficult it is for an electron beam to penetrate. Therefore, a clearer image can be observed with a high-pressure electron microscope (200 kV or more for a thickness of 0.25 μm). In the case of tabular grains, the position and number of dislocation lines of each grain as viewed from the direction perpendicular to the main plane can be determined from the photograph of the grain taken using an electron microscope as described above. Note that dislocation lines may or may not be visible depending on the tilt angle of the sample with respect to the electron beam.
In order to observe dislocation lines without omission, it is necessary to observe the particle photographs of the same particle at as many sample inclination angles as possible to determine the location of the dislocation lines.

The grains of the present invention having dislocation lines substantially only in the fringe portions (also referred to as “fringe dislocation type tabular grains” in the present specification) are those other than the fringe portions of the tabular grains, ie, the main plane portions. Refers to particles that do not contain three or more dislocation lines. Among high-density fringe dislocation type particles, a particle having three or more dislocation lines in a main plane portion (also referred to as “principal plane dislocation type tabular particle” in this specification) is distinguished from a fringe dislocation type particle. The proportion of each of the fringe dislocation type tabular grains and the principal plane dislocation type tabular grains in the emulsion grains can be determined by directly observing dislocation lines in at least 200 emulsion grains.

In the present invention, the fringe dislocation type tabular grains of silver halide have a total number of silver halide grains of 50%.
Account for more than%. Preferably, it accounts for 70% or more, particularly preferably 90% or more. When the fringe dislocation type tabular grains are less than 50% of the total number of silver halide grains,
The dislocation lines cannot be said to be localized, and the effects of homogeneity of each grain, efficient chemical sensitization, and concentration of latent image sites cannot be recognized.

In the present invention, it is preferable to determine the existing position and the number of dislocation lines by changing the inclination angle of the same particle in 5 ° steps using a high-voltage electron microscope and photographing four kinds of particle photographs.

In the silver halide emulsion of the present invention, tabular silver halide grains containing preferably 10 or more dislocation lines per grain account for 50% or more of the total number of silver halide grains, and the dislocation lines are high. Density. If the number is less than 50%, the graininess, gradation, antifogging property and the like are not sufficiently improved. The tabular silver halide grains are preferably 60%
As described above, it is particularly preferable to account for 70 to 100%. The proportion of 50% or more of the total number of silver halide grains is preferably 50 or more, more preferably 1% or more.
Tabular silver halide grains having 00 or more dislocation lines. When dislocation lines are densely present or when dislocation lines are observed to intersect each other, the number of dislocation lines per grain may not be clearly counted. However, even in these cases, approximately 10
It can be counted as many as twenty, thirty and thirty.

Next, a method of introducing dislocation lines which are uniform and high in density between grains and highly localized in the fringe portion according to the present invention will be described.

In the case of the ordinary dislocation line introduction method, first, tabular silver halide grains serving as a base are prepared by a general-purpose method, and then a high silver iodide phase (a halogen containing a large amount of silver iodide) is formed at the edge thereof. The dislocation lines are introduced by growing a low silver iodide phase after growing the silver iodide phase). The silver iodide content of the base grains is preferably from 0 to 15 mol%, and from 0 to 10 mol%.
More preferably, it is mol%. The halogen composition of the high silver iodide phase is optional, but the higher the silver iodide content, the better.

The amount of halogen added to form the high silver iodide phase on the base grains is 2 to 15 times the silver amount of the base grains.
Mol% is preferable, and more preferably 2 to 10 mol%,
Particularly preferably, it is 2 to 5 mol%. At this time, the high silver iodide phase is preferably present in the range of 5 to 80 mol%, more preferably 10 to 70 mol%, particularly preferably 20 to 60 mol% in terms of silver amount of the whole grains. To be within.

The preferred temperature in the dislocation line introduction process is 30 to 80 ° C., more preferably 35 to 75 ° C.
° C, particularly preferably 35 to 60 ° C.

In the present invention, as a source of iodide ions for forming a high silver iodide phase, at least 50% or more of the source is provided by a multiple twin prepared outside a reaction vessel having silver halide grains as a base. It is preferable to use a high silver iodide fine grain emulsion having a crystal ratio of 1% or less in order to obtain a remarkable effect of the present invention. It is further preferred that 70% or more of the iodide ion supply source in forming a high silver iodide phase be supplied by the fine grain emulsion, and most preferably 90% or more. still,
The multiple twin refers to a particle having two or more twin planes per particle, that is, a particle having two or more twins.

The reason why it is preferable to use a fine grain emulsion having a low multiple twin ratio is that fine grains having twin planes are difficult to redissolve. According to the study of the present inventors, when the grain sizes are almost the same, the solubility of silver halide fine particles is as follows: solubility of multiple twin grains << solubility of single twin grains <solubility of no twin grains. Therefore, a fine grain emulsion containing substantially no multiple twin grains is preferred. Here, "having substantially no multiple twins" means that the ratio of the number of particles having multiple twins is 1% or less,
It preferably means 0.3% or less, more preferably 0.1% or less, and still more preferably 0.01% or less. Most preferably, the mixed amount of the multiple twin particles cannot be detected. For details of the multiple twin grain structure, see H.S. Frie
Ser, et al., “Basics of the Photographic Process of Silver Halide, No. 3
Chapter, Akademische Verlagsgese
llshaft Frankfurt Main
(1968) "can be referred to.

The silver halide fine grains used in the present invention more preferably contain substantially no single twin grains. The ratio of the number of particles having single twin particles is preferably 5% or less, more preferably 1% or less, and even more preferably 0.1% or less.

It is preferable that the silver iodide-rich fine grain emulsion used in the present invention does not substantially contain screw dislocations. Here, “substantially” means that the particle number ratio is preferably 1% or less,
% Or less, more preferably 0.01% or less. The fine grain emulsion prepared by the method described later contains substantially no screw dislocation. Grains containing screw dislocations usually have a rectangular or rhombic projected shape. That is, the method described later also prevents the generation of screw dislocations.

Therefore, the advantage of using a silver iodide-rich fine grain emulsion having a multiple twin ratio of 1% or less, which is preferably used in the present invention, is that the dissolution rate is higher than that of ordinary fine silver iodide fine grains. It is presumed that a high-density silver iodide phase can be formed in a desired region. JP-A-8-190
The iodide ion releasing agent used in JP-A-164 No. 164 and the like includes a process of adding a pH adjusting agent when releasing iodide ions to raise the pH in the system. There is a disadvantage that concentration localization (locally high pH region) occurs and supply of iodide ions to the base particles becomes non-uniform among the particles. On the other hand, in the method of the present invention, silver iodide fine particles are uniformly mixed and dissolved in the reaction vessel, and iodide ions can be quickly supplied to the base grains. A silver phase can be formed.

The ratio of the number of twin grains is determined by growing a fine grain emulsion at a temperature of 40 ° C. or less, preferably 35 ° C. or less, to a point where a clear grain shape is exhibited under high supersaturation conditions without generating new nuclei. It can be determined by observing a transmission electron microscope photographic image (TEM image) of the replica of the particles. For details, the description in JP-A-2-14633 can be referred to.

The average grain size of the high silver iodide fine grains is preferably 0.2 μm or less, more preferably 0.1 μm or less.

Further, the grain size distribution of the silver iodide-rich fine grains used in the present invention is more preferably narrow. The variation coefficient (y) of the particle size distribution is (y <−80x + 4
5) is preferable, (y <-80x + 38) is more preferable, and (y <-80x + 30) is further preferable. Note that y
Is represented by (standard deviation of particle size distribution / average particle size) × 100%. x means the average particle size.

The halogen composition of the high silver iodide fine grains is not particularly limited, but the silver iodide content is preferably 80 mol% or more, most preferably 90 mol% or more.

Next, the multiple twin ratio used in the present invention is 1
% Is described below.

Usually, in order to form silver halide fine grains, it is necessary to use a silver halide having a solubility as low as possible (without using a silver halide solvent, at a temperature as low as possible and at the lowest solubility pAg of the silver halide solubility curve). In this case, an aqueous solution of a silver salt and a halide salt may be added in a short time while stirring efficiency is as high as possible. But,
The addition of an aqueous solution of a silver salt and a halide salt at a low temperature in a short period of time tends to increase the probability of forming the above-described multiple twin grains. It is inevitable to use these conditions to form silver halide fine grains. Therefore, other supersaturation factors at the time of nucleation are adjusted so that twin planes are not formed. Specifically, at least one of the following techniques may be used to adjust the following factors so that the generated particle characteristics fall within the above-mentioned specifications.

1). Increase the gelatin concentration.

As the gelatin concentration in the reaction solution is increased,
The twin plane formation probability is reduced. However, in the case of ordinary photographic gelatin, if it is too high, the reaction solution becomes highly viscous or gels particularly at a low temperature, and the stirring and mixing efficiency decreases. Therefore, the preferred gelatin concentration in the reaction solution at the start of the reaction is 1-1.
0% by weight, more preferably 3 to 8% by weight.

2). Use low molecular weight gelatin.

When the molecular weight of gelatin used is changed in the same weight% concentration solution, the probability of forming twin planes is the lowest when the molecular weight is in the range of 30,000 to 30,000. Therefore, it is preferable to use gelatin having a molecular weight of preferably from 5,000 to 60,000, more preferably from 30,000 to 30,000. Further, the low molecular weight gelatin is preferable because it does not increase the viscosity or gel even at a low temperature. For example, a 10% by weight solution of gelatin having a molecular weight of 10,000 does not gel even at 0 ° C. Therefore, it is particularly preferable because it does not gel even when the gelatin concentration is increased at a low temperature and the probability of forming twin planes is low. Preferred gelatin concentration is 1 to 15% by weight,
More preferably, it is 3 to 12% by weight. In this case, particularly when the average molecular weight is 10,000 or less, the viscosity of the fine grain emulsion becomes too low, and thus, when the stirring is stopped, the silver halide fine grains may slowly settle. To prevent this,
After the formation of the fine particles, a normal photographic gelatin solution having a molecular weight of about 100,000 can be added. The amount added
The fine particle emulsion can be arbitrarily adjusted within a range that is less than gelling and that the sedimentation speed is not too fast.
The weight ratio of the low molecular weight gelatin to the other dispersion medium at the time of forming the fine particles is preferably 30% by weight or more, more preferably 70% by weight or more.

3). The gelatin is added to at least one of the aqueous solutions of the silver salt and the halide salt.

Normally, the gelatin concentration is reduced in the vicinity of the region where the above solution is added, which is to increase the frequency of forming twin planes. Since supersaturation is particularly high near the addition port, a decrease in gelatin concentration near the addition port is not preferable. More preferably, gelatin is added to both the silver salt and the halide salt aqueous solution. In this case, H is used to prevent the silver salt solution from becoming white due to the formation of silver hydroxide or silver oxide.
An acid such as NO ₃ can be added to lower the pH to 5 or less. The gelatin concentration of gelatin having an average molecular weight of about 100,000 usually used in the photographic industry is preferably 1.6% by weight or less, from the viewpoint of preventing gelation of these aqueous solutions. 2% by weight is more preferred. On the other hand, when low-molecular-weight gelatin (average molecular weight of 1,000 to 60,000) is used, it is preferably used at 10% by weight or less, more preferably 0.2 to 10% by weight, because gelling does not occur.

4). Fine particles are formed in the vicinity of the equi-ionic point of silver ion and halide ion concentration.

When the excess halide ion concentration in the reaction solution during the formation of the fine particles is reduced, the probability of twin plane formation is reduced. Conversely, when nucleation is carried out in excess of silver ions, reducing the excess silver ion concentration lowers the probability of forming twin planes. That is, the smaller the excess amount of silver ions or halide ions, the lower the probability of forming twin planes. The preferred excess halide ion concentration or excess silver ion concentration when forming silver halide fine grains is 0 to 10 ^-2.1 M / L, preferably 0 to 10 ^-2.5 M / L. This condition corresponds to the above-mentioned low solubility region of the silver halide solubility curve, and is a preferable region as a condition for forming fine grains.

5). Lower the pH.

When gelatin is used as a dispersion medium, the lower the pH of the reaction solution, the lower the probability of twin plane formation. The dependence is greater for silver chloride-based than for silver bromide-based. The preferred pH range is 5 or less, more preferably 4-1.8.
It is. However, there is a case where the relationship between the pHs is inversely correlated. Therefore, practically, it is preferable to experimentally determine the optimum pH for each case.

6). Increase the concentration of unrelated salts.

The higher the concentration of an unrelated salt such as KNO ₃ or NaNO _{3 in the} reaction solution, the lower the probability of twin plane formation.
The preferred concentration is from 0 to 1 M / L, more preferably from 1 × 10 ^{-2 to} 1 M / L.

7). A silver salt and a halide salt are added by an accelerated addition method.

Usually, an aqueous solution of a silver salt and a halide salt is often added by a simultaneous mixing method at a constant speed for a short time. However, since the degree of supersaturation is highest in the initial stage of the addition and twin planes are likely to occur, the initial addition speed (at least for 10 seconds after the start of the addition) is reduced to 1 / n. Where n is
Preferably it is 1.2-30, More preferably, it is 2-30. Then, the generation probability of twin planes decreases, but the number of generated nuclei also decreases. This results in an increase in the final grain size when the same amount of silver is added. Therefore, it is then added at an m-fold addition rate (specifically 1.2 to 30 times, preferably 2 to 30 times the addition rate at which new nuclei are generated),
Increase the number of nuclei. The above n, m and the number of steps (the number of acceleration steps is 1 to 30) so that the number of generated nuclei when the addition of the same mole of the silver salt aqueous solution is completed exceeds the number of generated nuclei obtained by the conventional method. Integer).
In addition, the growth of the nucleus that first occurred was at a low temperature (45 ° C. or less),
Minimize by choosing low solubility conditions.
The relationship between these nucleation conditions and the frequency of twin plane formation is described in JP-A-63-92942 and JP-A-2-8-8.
No. 38 and Japanese Patent Application No. 63-223739 can be referred to.

The silver halide fine grains used in the present invention are preferably unwashed grains, and the grains are formed in a mixing vessel provided near the reaction vessel, and the grains are added to the reaction vessel immediately after the grains are formed. preferable. However, the mixing container is preferably a batch type mixing container. In the batch-type mixing vessel, a silver salt aqueous solution and a halide salt aqueous solution are mixed in a dispersion medium aqueous solution under conditions that suppress generation of multiple twin grains, thereby forming silver halide fine particles. Then, the silver halide fine particles are immediately supplied to a reaction vessel. JP-A-1-183417 discloses that a mixing vessel is provided outside a reaction vessel and connected to the reaction vessel, and a silver salt aqueous solution, a halide salt aqueous solution and a protective colloid aqueous solution are continuously supplied to the mixing vessel by a triple jet method. It discloses a method of mixing to form a silver halide fine grain emulsion and continuously supplying the fine grain emulsion to a reaction vessel. In this case, the supersaturation degree of the mixed portion becomes extremely high because the aqueous solution of the concentrated silver salt and the aqueous solution of the concentrated halide salt are directly mixed, and the ratio of the number of multiple twin grains in the fine grain emulsion is 2%.
It has the disadvantage of being higher. Also, the particle size distribution is broadened. According to the study of the present inventor, when such a silver halide fine grain emulsion having a high content of multiple twin grains is added to a base silver halide emulsion, the solubility is low, so that high density high iodide It has been found that it is difficult to form a silver phase and the uniformity between grains is also reduced.

A mixing apparatus which can be preferably used for preparing a silver halide fine grain emulsion having a remarkably small amount of multiple twin grains used in the present invention will be described.

A mixing apparatus for forming a silver halide fine grain emulsion in which the content of multiple twin grains is extremely small is as follows.
Although a known silver halide emulsion manufacturing apparatus can be used, an apparatus capable of rapidly and uniformly mixing an aqueous solution of the added silver salt and halide salt is preferable. Because the formation of silver halide fine grains is performed in a short time by adding a large amount of an aqueous solution of a silver salt and a halide salt, the supersaturation during grain formation becomes extremely high unless the mixture is rapidly and uniformly mixed. This is because defect particles having defects such as twin planes are easily generated with high frequency. Regarding this, Japanese Patent Application No. 63-2237
Reference can be made to the description in the specification of No. 39. An apparatus capable of rapidly and uniformly mixing is disclosed in JP-A-9-197587.
Can be cited.

The temperature for forming the high silver iodide fine grain emulsion of the present invention is preferably 0 to 45 ° C., more preferably 5 to 45 ° C.
35 ° C. A lower temperature is preferable because the particles become more fine and the coalescence reaction of the fine particles can be suppressed. The addition time is preferably from 5 seconds to 15 minutes, more preferably from 10 seconds to 5 minutes. If the addition time is increased, AgX
Is preferred because the number of moles / mL can be increased, but also has the disadvantage that the particle size of the produced particles increases. It is more preferable that the silver halide fine grain emulsion has a desired grain size and a large number of moles of silver halide / mL value. This is because the total amount of the fine grain emulsion is reduced and the production efficiency is increased. That is, a larger silver halide molar yield can be obtained in the same mixing vessel.

In order to increase the number of moles / mL of silver halide in the high silver iodide fine grain emulsion of the present invention, a method of preparing a fine grain emulsion and removing a part or all of water in the emulsion is used. Can also be used in combination. Specific examples include a vacuum distillation method and an ultrafiltration method, and known methods and apparatuses can be appropriately used.

Other methods and apparatus for forming the fine silver iodide fine grain emulsion used in the present invention, and methods and apparatuses for adding the emulsion to a reaction vessel can be preferably referred to the above-mentioned JP-A-9-197587.

After a high silver iodide phase is formed at the edge of the base grain, dislocation lines are introduced by forming a silver halide shell (low silver iodide phase) outside the silver iodide phase.

The composition of the silver halide shell may be either silver iodobromide or silver chloroiodobromide, but is preferably silver bromide or silver iodobromide. In the case of silver iodobromide, the preferred silver iodide content is 0.1 to 12 mol%, more preferably 0.1 to 10 mol%, most preferably 0.1 to 10 mol%.
3 mol%.

In the present invention, when forming the silver halide shell, a silver bromide content having a multiple twin ratio of 1% or less prepared outside a reaction vessel having silver halide grains serving as a base. Is preferably 70 mol% or more. The inventor presumes that the reason is the same as above.

The tabular silver halide emulsion of the present invention has a coefficient of variation of the silver iodide content distribution of each grain of 3% to 20%.
%. More preferably, 3% to 1%
5%. The silver iodide content of each grain can be measured by analyzing the composition of each grain using an X-ray microanalyzer. The variation coefficient of the silver iodide content distribution is the variation (standard deviation) of the silver iodide content of each grain.
Divided by the average silver iodide content.

In the method of the present invention for producing tabular silver halide grains having dislocation lines, any other known methods can be applied as far as they are not particularly limited.

The tabular silver halide emulsion of the present invention preferably contains a dopant in the grains. Here, the dopant means a substance other than silver and halide ions incorporated in the face-centered cubic crystal lattice structure of silver halide forming tabular grains. The introduction of the dopant
It can be introduced during grain nucleation or during grain growth. Among them, it is preferable to introduce the dopant in an appropriate amount at the beginning of the grain growth process and continue as it is, or to introduce the dopant at a later stage of the grain growth process. Various known dopants can be applied as the dopant to be introduced into the tabular silver halide grains of the present invention.

The tabular silver halide emulsion of the present invention is preferably subjected to chemical sensitization with chalcogen represented by sulfur and / or gold. A known method can be applied to the chemical sensitization method, for example, Research Disclosure.
Sure, December 1989, Item 308119,
It is described in Section III “Chemical sensitization”. Various known chemical sensitizers can be applied.

The tabular silver halide emulsion of the present invention is preferably subjected to spectral sensitization in order to increase sensitivity to light in a specific wavelength range. Various known sensitizing dyes and spectral sensitizing dyes can be used.
arch Disclosure, December 1989,
Item 308119, Section IV, "Spectral Sensitization and Desensitization".

There are no particular restrictions on the additives that can be added during the production of the silver halide emulsion of the present invention from the time of grain formation to the time of coating. Additives that can be added include a silver halide solvent (also referred to as a ripening accelerator), a dopant for silver halide grains [a Group VIII noble metal compound, and other metal compounds (gold, iron, lead, cadmium, etc.)] , Chalcogen compound, SCN compound, etc.], dispersion medium, antifoggant, stabilizer,
Sensitizing dyes (for blue, green, red, infrared, panchromatic, ortho, etc.), supersensitizers, chemical sensitizers (sulfur, selenium, tellurium, gold and Group 8 noble metal compounds, phosphorus compounds alone and A chemical sensitizer obtained by adding the combination, most preferably a chemical sensitizer comprising a combination of gold, sulfur and selenium compounds, reduction sensitizers such as stannous chloride, thiourea dioxide, polyamine and amine borane compounds), Fogging agents (organic fogging agents such as hydrazine compounds, inorganic fogging agents), surfactants (antifoaming agents, etc.), emulsion sedimentation agents, soluble silver salts (AgSCN, silver phosphate, silver acetate, etc.), latent agents Image stabilizers, pressure desensitization inhibitors, thickeners, hardeners,
A developer (hydroquinone-based compound or the like); a development modifier; For specific compounds and methods of use, the description in the following literature can be referred to.

In addition, with respect to the steps of water washing, chemical sensitization, coating, exposure and development of the emulsion, as well as the layer structure of the AgX emulsion coating and the method of preserving the coating, known techniques described in the following documents: Any combination with known compounds can be used. Research Disclosure No. 176
(No. 17643) (December, 197)
8), Vol. 184 (No. 18431) (Augus
t, 1979), Vol. 216 (No. 21728) (M
ay, 1982), Vol. 307 (No. 307105)
(November, 1989), "JCIA Monthly Report" 19
December 1984, pp. 18-27, "The Photographic Society of Japan", 4
9, 7-12 (1986); 52, 144-
166 (1989), JP-A-58-113926 to JP-A-58-113928, JP-A-59-9084.
No. 2, JP-A-59-142539, JP-A-62-25
No. 3159, No. 62-99751, No. 63-
Nos. 151618, 62-6251, 62
JP-A-115035, JP-A-63-305343,
JP-A-62-269958, JP-A-61-112142, JP-B-59-43727, and JP-A-63-243.
23739, 63-157474,
No. 61-109773, No. 62-54640, No. 62-263319, No. 62-20
Nos. 8241 and 63-129226, JP-A-1-131541, U.S. Pat.
No. 44, 4,707,436, T.P.
H. James, "The Theory of th
e Photographic Process (Fo
urthEdition) "Macmillan, Ne
w York, 1977; L. Zelikman
et al. "Making and Coating
Photographic Emulsion (The
Focal Press, 1964) ", p. Gla
fkides, Chemistry and Physics of Photography, Fifth
Edition de l'Usine Nowe
Ile, Paris, 1987, Second Ed
ition Paul Montel, Paris, 1
957, K.C. R. Hollister, "Journa
l ofImage. Sci. "31,148-156
P. (1987); E. FIG. Maskasky, “Jou
nal of Imaging Science "3
0, 247-254 (1986); Friese
R, et al., Academ, Basics of Silver Halide Photographic Process.
ische Verlagsgesellschaft
Frankfurt Am Main (1968),
Japanese Patent Application Nos. 1-76678, 1-258862 and 1-144724.

The tabular silver halide emulsion of the present invention can be used in various photographic materials by any conventional method. The tabular silver halide emulsion of the present invention is suitable for use in a multilayer photographic light-sensitive material having at least one silver halide emulsion layer. For example, the present invention can be applied to a photosensitive material for photography such as a color negative film and a color reversal film, and a medical photosensitive material.

[0070]

Next, the present invention will be described in more detail by way of examples, but embodiments of the present invention are not limited thereto.

Example 1 <Preparation of seed crystal emulsion> A seed crystal emulsion was prepared as follows.

Japanese Patent Publication Nos. 58-58288 and 58-58
No. 289, a silver nitrate aqueous solution (1.161 mol) was added to the following solution A1 adjusted to 35 ° C.
And a mixed aqueous solution of potassium bromide and potassium iodide (potassium iodide 2 mol%) while maintaining the silver potential (measured with a silver ion selective electrode using a saturated silver-silver chloride electrode as a reference electrode) at 0 mV. For 2 minutes to form nuclei. Subsequently, the temperature of the solution was raised to 60 ° C. over a period of 60 minutes, the pH was adjusted to 5.0 with an aqueous solution of sodium carbonate, and then an aqueous solution of silver nitrate (5.902 mol), potassium bromide and iodide were added. A mixed aqueous solution of potassium (2 mol% of potassium iodide) was added over 42 minutes by a double jet method while keeping the silver potential at 9 mV. After the addition was completed, the temperature was lowered to 40 ° C., and desalting and washing were immediately performed using a normal flocculation method.

The resulting seed crystal emulsion had an average sphere-equivalent diameter of 0.24 μm, an average aspect ratio of 4.8, and 90% or more of the total projected area of the silver halide grains had a maximum side ratio of 1.0.
~ 2.0 hexagonal tabular grains.

[Solution A1] Ossein gelatin 24.2 g Potassium bromide 10.8 g Sodium salt of polypropyleneoxy-polyethyleneoxy-disuccinate (10% ethanol solution) 6.78 ml 10% nitric acid 114 ml H ₂ O 9657 ml Preparation of Silver Fine Particle Emulsion SMC-1> A 7.06 mol silver nitrate aqueous solution and 7.06 mol iodide were stirred vigorously while 5 liters of a 6.0% by weight gelatin aqueous solution containing 0.06 mol potassium iodide was vigorously stirred. Potassium aqueous solution, 2 liters each, was added over 10 minutes. During this time, the pH was controlled at 2.0 using nitric acid, and the temperature was controlled at 40 ° C. After the preparation of the particles, the pH was adjusted to 5.0 using an aqueous sodium carbonate solution. The average particle size of the obtained silver iodide fine particles is 0.05 μm.
Met. A small amount of this silver iodide fine grain emulsion was
At 0 ° C., a silver nitrate solution and a potassium bromide solution were added, and the number ratio of multiple twin grains to single twin grains was determined. The result was as follows.

The ratio of the number of multiple twin grains: 6.1% The ratio of the number of single twin grains: 24.4% This emulsion is designated as SMC-1.

<Preparation of silver iodide fine grain emulsion SMC-2>
Except for changing to low molecular weight gelatin with an average molecular weight of 40,000,
Silver iodide fine grain emulsion SMC-2 was prepared in the same manner as in SMC-1.
Was prepared. The average particle size of the obtained silver iodide fine particles was SMC.
Same as -1. In addition, the result of having measured the particle number ratio of the multiple twin particle and the single twin particle similarly to SMC-1 is shown in Table 1.

<Preparation of silver iodide fine grain emulsion SMC-3>
Except for changing to low molecular weight gelatin with an average molecular weight of 10,000,
Silver iodide fine grain emulsion SMC-3 was prepared in the same manner as in SMC-1.
Was prepared. The average particle size of the obtained silver iodide fine particles was SMC.
Same as -1. In addition, the result of having measured the particle number ratio of the multiple twin particle and the single twin particle similarly to SMC-1 is shown in Table 1.

<Preparation of silver iodide fine grain emulsion SMC-4>
A silver iodide fine grain emulsion SMC-4 was prepared in the same manner as in SMC-1, except that the gelatin was changed to low molecular weight gelatin having an average molecular weight of 10,000 and the concentration was further changed to 12.0% by weight.
The average particle size of the obtained silver iodide fine particles was the same as that of SMC-1. In addition, the result of having measured the particle number ratio of the multiple twin particle and the single twin particle similarly to SMC-1 is shown in Table 1.

<Preparation of Emulsion Em-1> 4.5% by weight containing 0.178 mol of seed crystal Emulsion-1 and 0.5 ml of a 10% ethanol solution of sodium salt of polyisoprene-polyethyleneoxy-disuccinate. % Inert gelatin aqueous solution is maintained at 60 ° C., pAg is 9.8, p
After adjusting H to 5.0, particles were formed by the simultaneous mixing method with vigorous stirring according to the following procedure.

1) 0.071 mol of SMC-1 was added, and aging was performed for 2 minutes (introduction of dislocation lines).

2) 0.920 mol silver nitrate aqueous solution
069 mol of SMC-1 and aqueous potassium bromide solution
The pAg was added while maintaining the pH at 9.8 and the pH at 5.0 (growth of the outer layer).

Each solution was added at an optimum rate throughout the particle formation so as to prevent formation of new nuclei and Ostwald ripening between particles. After completion of the addition, the resultant was subjected to a water washing treatment at 40 ° C. using a normal flocculation method, and then gelatin was added and redispersed to adjust the pAg to 8.1 and the pH to 5.8.

The obtained emulsion was an emulsion composed of tabular grains having an equivalent circle diameter (length of one side of a cube of the same volume) of 1.21 μm and an average aspect ratio of 7.2.

<Preparation of Emulsions Em-2 to 4> Emulsion Em-1
Silver iodide fine grain emulsion SMC-1 in the preparation of
Emulsions Em-2 to Em-4 were respectively prepared in the same manner as Emulsion Em-1, except that each was changed to 2 to 4, respectively. Emulsion Em
The circle-equivalent diameter and average aspect ratio of −2 to 4 correspond to the emulsion Em−
It was almost the same as 1.

<Sensitization> Next, each of the emulsions Em-1 to 4 was subjected to the following sensitization.

0.5 mol of the emulsion sample was adjusted to 40 ° C., and spectral sensitizing dye-1, dye-2 and dye-3 were mixed at a ratio of 1: 1: 1 so that the total coverage was about 70%. Was added.
Then, potassium thiocyanate, sodium thiosulfate,
After optimal chemical sensitization by adding potassium chloroaurate, 4-hydroxy-6-methyl-1,3,3a, 7-
Tetraazaindene (TAI), 1-phenyl-5-mercaptotetrazole (PMT) was added. After all components were added, the mixture was heated to 60 ° C. to complete sensitization, and after cooling, more PMT was added.

[0087]

Embedded image

<Preparation of Single Layer Sensitive Material Sample> The sensitized emulsions Em-1 to Em-4 were respectively applied to a triacetyl cellulose film support coated with a gray silver antihalation layer, and this emulsion layer was Activator (SU-1 to SU-
4.3) containing (3) and bis (vinylsulfonyl) methane hardener (1.75% by weight based on the total weight of gelatin)
g / m ² gelatin layer. The emulsion coating amount was 0.646 gAg / m ² , and this layer also contained Coupler 1, a surfactant (SU-1 to SU-3 shown below), and a total amount of gelatin of 1.08 g / m ² . Thus, single layer light-sensitive material samples 1 to 4 were obtained for emulsions Em-1 to Em-4, respectively.

[0089]

Embedded image

<Evaluation Method> Each of the thus obtained single-layer photosensitive material samples 1 to 4 was subjected to wedge exposure with green light (G) for 0.01 second, followed by color development according to the following processing steps. The following relative sensitivity, granularity, and pressure characteristics were evaluated. Table 1 also shows the results.

The relative sensitivity is calculated as the reciprocal of the exposure amount that gives a density of Dmin (minimum density) +0.15 within one minute after exposure, and the sensitivity of sample 1 is set to 100. The values are shown as relative values (a value larger than 100 indicates higher sensitivity).

The granularity was represented by a relative value of a standard deviation (RMS value) of a change in density value generated when scanning a density of Dmin + 0.5 with a microdensitometer having an opening scanning area of 250 μm ² . The smaller the RMS value is, the better the graininess is and the more effective it is. The RMS value of Sample 1 was shown as a relative value with 100 being set (the smaller the value is, the better the value is.)

The pressure characteristic (pressure fog) is 23 ° C./55
% (Relative humidity), using a scratch strength tester (manufactured by Shinto Kagaku), 5
After scanning at a constant speed with a load of g, exposure and development processing are performed, and a density change ΔDmin of a portion where the load is applied at a density of Dmin is obtained.
Is shown as a relative value of 100 (the smaller the value is, the more improved the value is with respect to 100).

<< Color development processing >> Processing step Processing time Processing temperature Color development 2 minutes 50 seconds 38 ± 0.3 ° C. Bleaching 45 seconds 38 ± 2.0 ° C. Fixing 1 minute 30 seconds 38 ± 2.0 ° C. Stable 60 seconds 38 ± 5.0 ° C. Drying 1 minute 55 ± 5.0 ° C. The following color developing solution, bleaching solution, fixing solution and stabilizing solution were used.

<Color developing solution> Water 800 cc Potassium carbonate 30 g Sodium bicarbonate 2.5 g Potassium sulfite 3.0 g Sodium bromide 1.3 g Potassium iodide 1.2 mg Hydroxylamine sulfate 2.5 g Sodium chloride 0.6 g 4- Amino-3-methyl-N-ethyl-N- (β-hydroxylethyl) aniline sulfate 4.5 g Diethylenetriaminepentaacetic acid 3.0 g Potassium hydroxide 1.2 g Add water to make 1 liter, and add potassium hydroxide or 20% PH 10 using sulfuric acid. Adjust to 06.

<Bleaching solution> Water 700 cc 1,3-diaminopropanetetraacetic acid iron (III) ammonium 125 g ethylenediaminetetraacetic acid 2 g sodium nitrate 40 g ammonium bromide 150 g glacial acetic acid 40 g Add water to make 1 liter, and add ammonia water or glacial acetic acid Adjust to pH 4.4 using.

<Fixing solution> Water 800 cc Ammonium thiocyanate 120 g Ammonium thiosulfate 150 g Sodium sulfite 15 g Ethylenediaminetetraacetic acid 2 g After adjusting the pH to 6.2 using aqueous ammonia or glacial acetic acid, add water to make 1 liter.

<Stabilizing Solution> Water 900 cc paraoctylphenyl polyoxyethylene ether (n = 10) 2.0 g dimethylol urea 0.5 g hexamethylenetetramine 0.2 g 1,2-benzoisothiazolin-3-one 0.1 g siloxane ( L-77 manufactured by UCC) 0.1 g ammonia water 0.5 cc Water was added to make up to 1 liter. Adjust to 5.

Table 1 shows the above process and results.

[0100]

[Table 1]

As is clear from Table 1, Samples 3 and 4 of the present invention containing a silver halide emulsion produced according to the production method of the present invention have high sensitivity and improved graininess and pressure characteristics (pressure fog). ing. Among them, Sample 4 using Emulsion Em-4 having the lowest multiple twin ratio is particularly excellent.

As described above, according to the production method of the present invention, a silver halide photographic emulsion and a silver halide photographic light-sensitive material having high sensitivity, excellent graininess, and improved pressure fog can be obtained.

[0103]

According to the present invention, it is possible to improve the problems which have been insufficient with the conventional method of introducing dislocation lines into tabular silver halide grains. A method for producing a silver halide emulsion in which dislocation lines are introduced and inter-grain uniformity is significantly improved can be provided.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03C 7/00 510 G03C 7/00 510

Claims (4)

[Claims] 1. A tabular silver halide having a (111) major plane, an average silver bromide content of 70 mol% or more, an aspect ratio of 2 or more, and an equivalent circle diameter of 0.5 μm or more. The grains account for 90% or more of the total projected area, and 50% or more of the tabular silver halide grains have a silver halide emulsion in which 10 or more dislocation lines are localized substantially only in the fringe portion. In the production method, the multiple twin ratio prepared outside the reaction vessel having the base silver halide grains is 1%.
A method for producing a silver halide emulsion, characterized in that a high silver iodide-containing phase is formed by supplying the following high silver iodide fine grain emulsion to the silver halide grains serving as the base. 2. The method for producing a silver halide emulsion according to claim 1, wherein the average grain size of the high silver iodide fine grain emulsion is 0.2 μm or less. 3. A flat plate having a dispersion medium, a (111) main plane, an average silver bromide content of 70 mol% or more, an aspect ratio of 2 or more, and a circle equivalent diameter of 0.5 μm or more. Tabular silver halide grains occupy 90% or more of the total projected area, and 50% or more of the tabular silver halide grains have at least 10 dislocation lines localized only in the fringe portion. A silver halide emulsion containing silver halide grains, wherein the tabular silver halide grains have a multiple twin ratio of 1
% Silver halide grains having a high silver iodide-containing phase formed by supplying a high silver iodide fine grain emulsion having a silver iodide content of not more than 1%. 4. A silver halide photographic material having at least one silver halide emulsion layer on a support, wherein the silver halide emulsion layer according to claim 3 is contained in the silver halide emulsion layer. A silver halide photographic light-sensitive material comprising: