JPH11125876A - Silver halide photographic emulsion and manufacture of silver halide photographic emulsion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the silver halide emulsion high in sensitivity and low in fog and superior in storage stability with the lapse of time and processing characteristics by forming silver halide grains specified in the silver halide composition on the surface of each grain measured by the low speed ion scattering spectroscopy in the thickness direction as follows; specified in an intensity ratio of each silver halide or higher and attenuating in the intensity ratio from the outermost surface to the inner side to a specified value in the specified range of the thickness direction. SOLUTION: The silver halide grains in the emulsion comprise platelike silver halide grains occupying >=50% of the projection areas of the total silver halide grains and having an aspect ratio of >=5, and the silver halide composition in the outermost surface of the total silver halide grains in the thickness direction measured by the low speed ion scattering spectroscopy is as follows; the I/(I+Br) intensity ratio being >=0.7 in the outermost surface and attenuating to <=1/3 in the range of 2 nm from the outermost surface, and the platelike silver halide grains each has a high iodine concentration unform surface layer, and the surfaces of the emulsion silver halide grains are subjected to iodine oxidation treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silver halide photographic emulsion having high sensitivity, low fog, excellent storage stability over time, and excellent processing characteristics, and a method for producing the silver halide photographic emulsion.

[0002]

2. Description of the Related Art In recent years, demands for higher sensitivity, higher image quality, and improved storage stability of silver halide photographic materials (hereinafter, also referred to as "photosensitive materials") have been increasing. Further, with the recent speeding up of development processing, demands on processing characteristics of photosensitive materials have become higher.

A technique for increasing the surface iodine content of a silver halide emulsion is as follows.
This is a typical technique for improving the storage stability. For example, a technique for performing halide conversion on the particle surface is disclosed in
-305343 and JP-A-3-121442. Also, in Japanese Patent Publication No. 5-75096,
A technique for designing the surface portion of silver halide grains with high iodine is disclosed.

Many of the performance fluctuations due to storage of photosensitive materials are
This is due to the elimination of the sensitizing dye adsorbed on the surface of the silver halide grains, and the adsorbing power between the sensitizing dye and the silver halide grains is enhanced by increasing the iodine content of the grain surface. In other words, it is expected that the preservability is improved by improving the adsorption power between the sensitizing dye and the silver halide grains by the surface high iodine technique, and that the sensitivity can be increased by increasing the effective adsorption amount of the sensitizing dye.

However, the presence of silver iodide at a high concentration on the grain surface deteriorates the developability of silver halide grains,
In addition, there is a problem that sensitization nucleus aggregation during chemical sensitization is inhibited. In order to solve such a problem, a technique for forming a minimum necessary high iodine layer only on the outermost surface of an emulsion is disclosed in Japanese Patent Application Laid-Open No. Hei 6-337486. This technique is a technique of forming a surface high iodine layer by adding silver halide fine grains containing silver iodide, and is different from previous techniques of increasing surface iodine. However, since the mechanism of dissolution / growth of silver halide grains is used, dissolution / recrystallization of the outermost surface of the grains has occurred, and in terms of increasing the surface iodide and thinning the high iodide layer. There was a limit.

As a method of increasing the iodine content of the particle surface by a mechanism different from the method described above, for example, Japanese Patent Application Laid-Open No. Hei 8-6906.
No. 4 discloses an oxidation treatment with iodine.

The inventors of the present invention have proposed a method in which surface oxidation treatment with iodine is applied to a tabular emulsion having a high aspect ratio, whereby iodine ions are introduced into the surface of a smaller amount of grains to improve the storage stability, and achieve high sensitivity and low sensitivity. It has been found that an emulsion which is fogged and excellent in processability can be obtained. Further, it was discovered by ISS (slow ion scattering spectroscopy) that the emulsion obtained by this method had a higher iodine and a thinner layer formed on the surface than the conventional emulsion.

The present inventors have further found that the above effects are remarkable in emulsions having high monodispersity.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a silver halide photographic emulsion having high sensitivity and low fog, excellent storage stability over time, and excellent processing characteristics, and a method for producing the silver halide photographic emulsion. It is in.

[0010]

The above object of the present invention has been attained by the following constitutions.

(1) 50% or more of the total projected area is composed of tabular silver halide grains having an aspect ratio of 5 or more, and
Silver halide photograph in which the I / (I + Br) intensity ratio of the outermost surface is 0.7 or more and the intensity ratio attenuates to 1/3 or less within 20 ° from the outermost surface in the measurement of the halide composition in the thickness direction according to emulsion.

(2) A silver halide photographic emulsion comprising tabular silver halide grains having an aspect ratio of 5 or more in a proportion of 50% or more of the total projected area, wherein the tabular grains have a high iodine uniform surface layer on the main plane of the grains.

(3) A silver halide photographic emulsion in which 50% or more of the total projected area is composed of tabular silver halide grains having an aspect ratio of 5 or more, and the surfaces of the emulsion grains are subjected to an iodine oxidation treatment.

(4) The silver halide photographic emulsion according to (1), (2) or (3), wherein the silver halide grains constituting the silver halide photographic emulsion have a monodispersion of 25% or less in particle size distribution. .

(5) A method for producing a silver halide photographic emulsion comprising tabular silver halide grains having an aspect ratio of 5 or more in an area ratio of 50% or more of the total projected area where iodine is added at a pAg of 8.60 or less.

(6) The method for producing a silver halide photographic emulsion according to (5), wherein the silver halide grains constituting the silver halide photographic emulsion have a particle size distribution of 25% or less.

The effects of the present invention are considered to have a large synergistic effect due to the following three points.

By introducing a high iodine layer by a process called iodine oxidation without dissolving and growing silver halide, a higher iodine layer on the outermost surface and a thinner high iodine layer can be obtained. .

By using a monodisperse emulsion, a uniform high iodine layer was formed between grains.

By using high aspect ratio particles,
A flat main plane optimal for forming a uniform high iodine layer was obtained.

Hereinafter, the configuration of the present invention will be described in detail.

The silver halide grains contained in the silver halide emulsion of the present invention are tabular grains.

Tabular grains are crystallographically classified as twins. Twins are silver halide crystals having one or more twin planes in one grain, and the classification of twins is based on a report by Klein and Moiser in Photographic Corspondents (Photographiche Ko).
rrespondenz) 99, 100, 100
Vol., P. 57.

The tabular grains in the present invention preferably have two or more twin planes parallel to the main plane.

The twin plane can be observed with a transmission electron microscope. The specific method is as follows. First,
A silver halide emulsion is coated on a support such that the tabular grains contained are oriented substantially parallel to a main plane to prepare a sample. This is cut using a diamond cutter to obtain a thin section having a thickness of about 0.1 μm. By observing this section with a transmission electron microscope, the presence of twin planes can be confirmed.

The distance between the twin planes of the tabular grain of the present invention is determined by observing the section using a transmission electron microscope as described above. The distance between the twin planes having the shortest distance among the even twin planes parallel to the main plane is determined for each particle, and the average is obtained by averaging.

The average distance between twin planes is 0.01 to 0.05.
μm is preferable, and 0.013 to 0.02 is more preferable.
5 μm.

The distance between twin planes is a factor affecting the supersaturation state at the time of nucleation, for example, various factors such as gelatin concentration, gelatin species, temperature, iodine ion concentration, pBr, pH, ion supply speed, and stirring speed. It can be controlled by appropriate selection in a combination of factors. In general, as the nucleation is performed in a highly supersaturated state, the distance between twin planes can be reduced. For details on the supersaturation factor, see, for example,
No. 92924 or JP-A-1-213637 can be referred to.

The thickness of a tabular grain can be obtained by observing a section using a transmission electron microscope as described above, similarly obtaining the thickness of each grain, and performing averaging. The thickness of the tabular grains is preferably from 0.05 to 1.5 μm, more preferably from 0.07 to 0.50 μm.

The grain size of the tabular grains is represented by the equivalent circle diameter of the projected area of the silver halide grains (the diameter of a circle having the same projected area as the silver halide grains), and is 0.1 to 5.0.
μm is preferred, and more preferably 0.2 to 2.5 μm.

The tabular grains of the present invention comprise 50% of the total projected area.
As described above, the aspect ratio (particle diameter / grain thickness) is 5 or more, and preferably, 50% or more of the total projected area has an aspect ratio of 6 to 8.

The particle diameter can be obtained, for example, by photographing the particles with an electron microscope at a magnification of 10,000 to 70,000 and measuring the particle diameter on the print or the area at the time of projection (the number of measured particles). Are indiscriminately 1000 or more). Here, the average particle diameter r, the particle size r when the product n _i × r _i ³ of the frequency n _i and r _i ³ of particles having a particle size r _i becomes maximum
It is defined as i (three significant digits, the smallest digit is rounded off to the nearest 5).

The silver halide emulsion of the present invention is preferably a monodispersed silver halide emulsion.

In the present invention, the monodisperse emulsion is defined as (particle size r
The standard deviation of _i / average particle size r) × 100 = particle size distribution (coefficient of variation of particle size)% is defined as 25% or less, preferably 20% or less, more preferably 20% or less. 1
Say less than 6%.

The tabular grain of the present invention is preferably a grain (core / shell type grain) composed of a core serving as a nucleus and a shell covering the core, and the shell is composed of one or more layers. It is formed.

When the tabular grains are composed of the above-described core / shell type grains, the halogen composition of the core and the shell can be arbitrarily selected, but the ratio of the core is 1% of the total silver content of the grains.
It is preferably set to ６０60%, more preferably 4 to 40%.

When the silver iodide content of the core and the shell is different, the difference in the silver iodide content of the core and the shell preferably has a sharp boundary. Those having at least one layer interposed are also preferably used.

When the tabular grains contain the core / shell type silver halide grains having the above-mentioned intermediate layer, the volume of the intermediate layer is preferably 0.1 to 20%, more preferably 0.1 to 20% of the total silver content of the grains. 5 to 10%.

The difference in silver iodide content between the intermediate layer and the shell is preferably such that the silver iodide content in the intermediate layer is higher than the silver iodide content in the shell by 2 mol% or more.

The average silver iodide content of the tabular grains in the present invention is preferably at most 10 mol%, more preferably at most 7 mol%, further preferably at most 4 mol%.

The tabular grains of the present invention are emulsions mainly containing silver iodobromide, but may contain silver halide of another composition, for example, silver chloride, as long as the effects of the present invention are not impaired.

The distribution state of silver iodide in the core / shell type silver halide grains can be detected by various physical measurement methods, and is described, for example, in the Abstracts of the 1981 Annual Meeting of the Photographic Society of Japan. Such luminescence can be measured by low-temperature luminescence measurement or X-ray diffraction.

As a means for forming tabular grains, various methods well known in the art can be used. That is, any combination of the single jet method, the controlled double jet method, the controlled triple jet method, etc. can be used. However, in order to obtain advanced monodisperse grains, it is necessary to form silver halide grains. It is important to control the pAg in the liquid phase to be adjusted according to the growth rate of the silver halide grains. As the pAg value, a range of 7.0 to 11.5 is used, and preferably 7.5.
To 11.0, more preferably 8.0 to 10.5.

In determining the rate of addition, see
References can be made to the techniques described in US Pat.

In the production of tabular grains, a known silver halide solvent such as ammonia and thioether may be used, or a silver halide solvent may not be used.

The tabular grains may be either grains whose latent image is mainly formed on the surface or grains mainly formed inside the grain.

The tabular grains of the present invention can be prepared in the presence of a dispersion medium.
That is, it is produced in a solution containing a dispersion medium. Here, the aqueous solution containing a dispersion medium refers to a solution in which a protective colloid is formed in an aqueous solution by gelatin or another substance capable of forming a hydrophilic colloid (a substance capable of serving as a binder), and preferably a colloidal protective substance. It is an aqueous solution containing gelatin.

When gelatin is used as the protective colloid, the gelatin may be either lime-treated or acid-treated. Details of the method for producing gelatin are described in Arthur Guice's, The Macromolecular Chemistry of Gelatin (Academic Press, 1964).

Examples of hydrophilic colloids other than gelatin that can be used as protective colloids include, for example, gelatin derivatives, graft polymers of gelatin and other polymers,
Proteins such as albumin and casein; cellulose derivatives such as hydroxyethylcellulose, carboxymethylcellulose and cellulose sulfates; sugar derivatives such as sodium alginate and starch derivatives; polyvinyl alcohol, polyvinyl alcohol partial acetal, poly-
N-vinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinylimidazole,
There are many types of synthetic hydrophilic polymeric substances, such as homo- or copolymers such as polyvinylpyrazole.

In the case of gelatin, it is preferable to use a gelatin having a jelly strength of 200 or more in a puggy method.

In the present invention, the tabular grains may be formed by a cadmium salt,
Metal ions are added using at least one selected from zinc salts, lead salts, thallium salts, iron salts, rhodium salts, iridium salts, indium salts (including complex salts), and these are added to the inside and / or the surface of the particles. A metal element can be contained.

The tabular grains may be those from which unnecessary soluble salts have been removed after the growth of the silver halide grains has been completed, or may be those which are still contained. In addition, desalting can be performed at any point during silver halide growth, as in the method described in JP-A-60-138538. When the salts are removed, Research Disclosure (hereinafter, referred to as R)
(Abbreviated as D) 17643 No. II. More specifically, in order to remove soluble salts from the emulsion after the formation of the precipitate or after the physical ripening, a Nudel washing method performed by gelatinizing gelatin may be used,
Further, a precipitation method (flocculation) using an inorganic salt, an anionic surfactant, an anionic polymer (eg, polystyrene sulfonic acid), or a gelatin derivative (eg, acylated gelatin, carbamoylated gelatin) may be used.

In the present invention, the high iodine layer on the grain surface is
It is detected by SS (slow ion scattering spectroscopy) measurement. The ISS measurement is a well-known surface analysis technique today. Regarding the ISS measurement of a silver halide emulsion, for example, Journal of Photographic Science (Journal of Photographic Science)
Science, Vol. 35, p. 155 (1987).

The ISS measurement is an analysis method in which ions of a rare gas or the like are used as a probe and the composition of the outermost solid layer is analyzed by an ion scattering phenomenon. Further, the composition information in the thickness direction can be obtained by performing the measurement with the sputtering phenomenon, that is, while shaving off the sample surface.

The specific method of measuring the ISS of a silver halide emulsion is as follows.

The silver halide emulsion was diluted with pure water and allowed to stand.
By repeatedly removing the supernatant, a mixture such as gelatin is removed. After adding pure water again and stirring and dispersing,
The solution is dropped on a hydrophilized Si substrate. At this time, by appropriately diluting the dispersion, the particles do not overlap,
In addition, a sample in which the main plane of tabular grains is oriented on the substrate surface can be prepared. After drying, the periphery is scraped off with a cutter, leaving a few mm square, and used as a measurement sample. The state of the sample, such as the particle overlap and the degree of orientation of the main plane of the tabular grains, can be confirmed by observing a part of the sample with a scanning electron microscope or the like.

In the present invention, the measurement of ISS needs to be performed on a sample whose main plane is oriented on the substrate surface. The measured value of the I / (I + Br) intensity ratio on the outermost surface of the ISS indicates the characteristics of the main plane of the tabular grains.

An example of the measurement conditions will be described. N as ion species
e ⁺ , an ion acceleration voltage of 1 kV, and 350 to 65
The range of 0 eV is measured. Ag (around 530 eV), B
The area intensities of the peaks of r (around 450 eV) and I (around 600 eV) can be obtained, and the ratio of these intensities can be plotted as a function of the thickness from the outermost surface of the particles.

As described above, the depth profile of the I / (I + Br) intensity ratio can be created.

In the present invention, I / (I + B
r) The measured value of the intensity ratio is a measured value in the first scan in which the sputter thickness is adjusted to 3 to 7 °. Similarly, the sputter thickness in each scan after the first scan is also 3 to 7 cm / 1.
Need to adjust to scan.

The high iodine uniform surface layer on the main plane of the grains of the silver halide emulsion of the present invention can be obtained by measuring the outermost I
/ (I + Br) is detected when the intensity ratio is 0.7 or more, and the intensity ratio attenuates to 1/3 or less within a sputter thickness of 20 °.

The preferred value of the I / (I + Br) intensity ratio on the outermost surface is 0.75 or more, more preferably 0.8 or more. The strength ratio is 1/4 within a sputter thickness of 20 mm or less.
It is preferably attenuated below, and more preferably attenuated below 1/5.

The tabular grains of the present invention comprise 50% of the total projected area.
It is preferable that the above particles have 5 or more dislocation lines per particle. Dislocations of silver halide grains are described, for example, in J. Am.
F. Hamilton: Photo. Sci. Eng. ,
111, 57 (1967), T.I. Shiozawa:
J. Soc. Photo. Sci. Japan, l3
5, 213 (1972) can be observed by a direct method using a transmission electron microscope at a low temperature. That is, the silver halide grains taken out from the emulsion so as not to apply enough pressure to generate dislocations on the grains are placed on a mesh for observation with an electron microscope to prevent damage (printout, etc.) by an electron beam. Observation is performed by a transmission method while the sample is cooled. At this time, the higher the thickness of the particles, the more difficult it is for an electron beam to pass therethrough.
The use of an electron microscope (200 kV or more for particles having a thickness of μm) enables more clear observation.

From the photograph of the particles obtained by such a method, the position and number of dislocations for each particle when viewed from the direction perpendicular to the main plane can be determined.

In the tabular grains, the dislocation lines are preferably located near the outer periphery, near the ridge line, or near the apex of the tabular grains, and more specifically, from the center of the main plane of the tabular grains. When a straight line parallel to the main plane is drawn toward the side surface of the grain, and the length of the straight line to the outer surface is L, 5% or more dislocations per grain of 50% or more of the total projected area per grain. It is preferable to have lines in the region from 0.50L to L, more preferably 50 lines of the total projected area.
% Or more of the grains have at least 10 dislocation lines per grain.
70L to L, particularly preferably 50% or more of the total projected area of particles per particle is 20%.
It has more than one dislocation line in the range of 0.80L to L. The direction of the dislocation line is generally from the center toward the outer surface (side surface), but often meanders.

As a method of introducing dislocation lines into tabular grains, for example, a method of adding an aqueous solution containing iodide ions such as potassium iodide and a water-soluble silver salt solution by double jet, or adding only a solution containing iodide ions A method of adding a fine grain emulsion containing silver iodide, or JP-A-6-11781.
A dislocation which is a source of a dislocation line can be formed at a desired position by using a known method such as a method using an iodide ion releasing agent as described in JP-A-6-27564. Among these methods, a method of adding a fine grain emulsion containing silver iodide and a method of adding an iodide ion releasing agent are preferable. In the present invention, the dislocation line introduction position is a portion where iodide ions are introduced into the particles by the above-described method.

In the present invention, iodine can be added at any stage after the completion of silver halide grain formation.
Here, the formation of silver halide grains refers to a step of forming a precipitate by adding a soluble silver salt solution and a soluble halide salt solution to a solution containing a protective colloid. It is preferable to add iodine before the chemical sensitization step.

The iodine can be added by dissolving it in any solvent, but it is preferable to add it by dissolving it in alcohols, and it is particularly preferable to add it by dissolving it in methanol. Further, after the iodine dissolved in the solvent is added to an aqueous solution containing gelatin and other protective colloids, an aqueous solution containing the gelatin and other protective colloids can be added to the silver halide emulsion.

The iodine can be added in two or more portions. Also, iodine can be added continuously at a constant rate, or can be added by controlling the flow rate like a function. It may be added instantaneously without controlling the flow rate.

The preferred addition amount of iodine in the present invention is
It is 2 × 10 ^{−5 to} 5 × 10 ⁻³ mol per mol of silver as I atom, more preferably 5 × 10 ⁻⁵ to 1 × 10 ⁻³ mol per mol of silver as I atom, and Preferably I
The amount is 1 × 10 ^{−4 to} 6 × 10 ⁻⁴ mol per mol of silver.

The pAg of the emulsion when iodine is added is 8.
It is necessary to be 60 or less, and it is preferred that it is 8.4 or less. The pH and temperature at the time of adding iodine are arbitrary, but the pH is preferably 3.0 to 8.0,
More preferably, it is 4.0 to 7.0. Temperature is 60
It is preferable that the temperature is not higher than ° C.

The tabular grains of the present invention can be chemically sensitized by a conventional method. That is, sulfur sensitization, selenium sensitization, a noble metal sensitization method using gold or another noble metal compound, or the like can be used alone or in combination. Further, tabular grains can be optically sensitized to a desired wavelength region using a dye known as a sensitizing dye in the photographic industry. These sensitizing dyes may be used alone or in combination of two or more. A dye which does not itself have a spectral sensitizing effect together with the sensitizing dye, or a compound which does not substantially absorb visible light, and which contains a supersensitizer which enhances the sensitizing effect of the sensitizing dye in the emulsion. Is also good.

Further, antifoggants, stabilizers and the like can be added to the tabular grains.

It is advantageous to use gelatin as the binder. The emulsion layer and other hydrophilic colloid layers
It can be hardened and can contain a plasticizer, a dispersion (latex) of a water-insoluble or soluble synthetic polymer.

The silver halide photographic emulsion of the present invention can be used for a wide range of light-sensitive materials, and is preferably used for color light-sensitive materials such as color films for general use and motion pictures, color paper, color reversal films and color reversal papers. Can be.

A coupler is used in the emulsion layer of the color light-sensitive material. Furthermore, a development accelerator, a developing agent, a silver halide solvent, a toning agent, a hardening agent, by coupling with a competing coupler having an effect of color correction and an oxidized form of a developing agent.
Compounds that release photographically useful fragments, such as fog agents, antifoggants, chemical sensitizers, spectral sensitizers and desensitizers can be used.

The light-sensitive material can be provided with auxiliary layers such as a filter layer, an antihalation layer, and an irradiation prevention layer. In these layers and / or the emulsion layers, dyes which are discharged from the light-sensitive material or bleached during the development processing may be contained.

The photosensitive material may contain a matting agent, a lubricant, an image stabilizer, a formalin scavenger, an ultraviolet absorber, a fluorescent brightener, a surfactant, a development accelerator and a development retarder. As a support for the photosensitive material, polyethylene-laminated paper, polyethylene terephthalate film,
Baryta paper, cellulose triacetate and the like can be used.

[0079]

EXAMPLES The present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples.

Example 1 (Preparation of Base Particles) (Preparation of Emulsion Em-1) [Nucleation Step] The following reaction mother liquor (Gr-1) in a reaction vessel
While stirring at 400 rpm using a mixing and stirring apparatus described in JP-A-62-160128.
The pH was adjusted to 1.96 with N sulfuric acid. Thereafter, the solution (S-1) and the solution (H-1) were added at a constant flow rate for one minute by using a double jet method to form nuclei.

(Gr-1) Alkali-treated inert gelatin (average molecular weight 100,000) 40.50 g Potassium bromide 12.40 g Finish up to 16.2 liters with distilled water (S-1) 862.5 g of silver nitrate 4 with distilled water (H-1) Potassium bromide 604.5 g Finish with distilled water to 4.06 liters [Maturation step] After the above nucleation step, add the (G-1) solution and take 30 minutes. The temperature was raised to 60 ° C. During this time, the silver potential of the emulsion in the reaction vessel (measured with a silver ion selective electrode using a saturated silver-silver chloride electrode as a reference electrode) was controlled at 6 mV using a 2N aqueous potassium bromide solution. Subsequently, the pH was adjusted to 9.3 by adding an aqueous ammonia solution, and after further holding for 7 minutes, the pH was adjusted to 6.1 using an aqueous acetic acid solution.
During this time, the silver potential was adjusted to 6 m using a 2N potassium bromide solution.
V.

(G-1) Alkali-treated inert gelatin (average molecular weight 100,000) 173.9 g 10% by weight methanol solution of surfactant (EO-1) 5.80 ml Finish to 4.22 liters with distilled water EO- 1: HO (CH ₂ CH ₂ O) _m (CH (CH ₃ ) CH
_{2 O) 19.8 (CH 2 CH} 2 O) n H (m + n = 9.77) after [the particle growth step] ripening step is completed, followed above using the double jet method (S-1) solution and (H-1 ) The remaining liquid was added for 37 minutes while accelerating the flow rate (the ratio of the addition flow rate at the end to the start was about 12 times). (G-
2) The solution was added, and the stirring was adjusted to 550 rpm, followed by 2.11 liters of the solution (S-2) and (H-
2) The solution was added for 40 minutes while accelerating the flow rate (the ratio of the addition flow rate at the end and the addition was about twice). During this time, the silver potential of the emulsion was controlled at 6 mV using a 2N potassium bromide solution.

After completion of the addition, the emulsion temperature in the reaction vessel was reduced to 15
The temperature was lowered to 40 ° C. in a few minutes. Thereafter, the silver potential in the reaction vessel was adjusted to −39 mV using a 3N aqueous solution of potassium bromide, and then 407.5 g of the liquid (F-1) was added.
(S-2) The remaining liquid and the liquid (H-3) are accelerated while increasing the flow rate (the ratio of the addition flow rate at the end to the start is about 1.2 times) 25
Minutes.

(S-2) Silver nitrate 2.10 kg Finished to 3.53 liters with distilled water (H-2) Potassium bromide 859.5 g Potassium iodide 24.45 g Finished to 2.11 liters with distilled water (H- 3) Potassium bromide 587.0 g Potassium iodide 8.19 g Finished to 1.42 liters with distilled water (G-2) Ossein gelatin 284.9 g 10% by weight methanol solution of surfactant (EO-1) 7. Finish up to 1.93 liters with 75 ml distilled water. (F-1) 407.5 g of a fine grain emulsion (*) composed of 3% by weight of gelatin and silver iodide grains (average grain size: 0.05 μm) The preparation method is as follows.

6.0 containing 0.06 mol of potassium iodide
To 5 liters of a 5% by weight gelatin solution, 2 liters of an aqueous solution containing 7.06 mol of silver nitrate and 7.06 mol of potassium iodide were added over 10 minutes. During the fine particle formation, the pH was controlled at 2.0 using nitric acid, and the temperature was controlled at 40 ° C. After the formation of the particles, the pH was adjusted to 6.0 using an aqueous solution of sodium carbonate. 12.53 finished weight
kg.

After completion of the above-mentioned grain growth, Japanese Patent Application Laid-Open No. 5-726
Desalting is performed according to the method described in No. 58, and then gelatin is added to disperse the mixture.
g was adjusted to 8.05. The emulsion thus obtained was Em
-1.

From the electron micrograph of the obtained emulsion particles,
It was confirmed that the tabular grains had an average particle size of 1.50 μm (average value of the circle-converted diameter of the projected area), an aspect ratio of 7.4 (50% of the total projected area), and a particle size distribution of 15.0%.

(Preparation of Emulsion Em-2) In the grain growth step of the emulsion Em-1, the portion for controlling the silver potential to 6 mV was controlled to 15 mV, and the portion for adjusting the silver potential to -39 mV was changed to -3.
Except that the voltage was adjusted to 0 mV, Em-
2 was prepared.

From the electron micrograph of the obtained emulsion particles,
It was confirmed that the tabular grains had an average particle size of 1.37 μm (average value of the circle diameter of the projected area), an aspect ratio of 5.6 (50% of the total projected area), and a particle size distribution of 16.0%.

(Preparation of Emulsion Em-3) In the grain growth step of Emulsion Em-1, the portion for controlling the silver potential to 6 mV was controlled to 24 mV, and the portion for adjusting the silver potential to -39 mV was changed to -3 mV.
Except that the voltage was adjusted to 0 mV, Em-
3 was prepared.

From the electron micrograph of the obtained emulsion particles,
It was confirmed that the tabular grains had an average particle size of 1.25 μm (average value of the circle-converted diameter of the projected area), an aspect ratio of 4.5 (50% of the total projected area), and a particle size distribution of 16.0%.

(Preparation of Emulsion Em-4) Emulsion Em-1 was prepared except that the ripening step was changed as follows.
Em-4 was prepared in the same manner as for m-1.

[Maturation Step] After the above nucleation step, (G
-1) The solution was added, and the temperature was raised to 60 ° C. over 30 minutes. During this time, the silver potential of the emulsion in the reaction vessel (measured with a silver ion selective electrode using a saturated silver-silver chloride electrode as a reference electrode) was controlled at 6 mV using a 2N potassium bromide solution. 1 as it is
After stirring was continued for 5 minutes, the pH was adjusted to 6.1 with potassium hydroxide. During this time, the silver potential was controlled at 6 mV using a 2N potassium bromide solution.

From the electron micrograph of the obtained emulsion particles,
It was confirmed that the tabular grains had an average particle size of 1.53 μm (average value of the circle-converted diameter of the projected area), an aspect ratio of 7.3 (50% of the total projected area), and a particle size distribution of 28.0%.

Example 2 (Preparation of surface high iodine particles) Em-1 prepared in Example 1
Was used as a base grain to prepare a surface-high iodine emulsion.

While stirring Em-1 at 40 ° C., pAg
After confirming that it is 8.05, as shown in Table 1,
After adding a methanol solution of iodine, a silver iodide fine grain emulsion (F-1) or an aqueous solution of potassium iodide, the mixture was ripened for 20 minutes, and pAg
Was again adjusted to 8.05.

[0097]

[Table 1]

<< Measurement of ISS >> The ISS was measured for Em-1 and the emulsions prepared above. A specific method will be described below.

The emulsion was diluted with a 20-fold volume of distilled water and left overnight at room temperature. The supernatant was discarded, and distilled water was added to the remaining precipitate to obtain an appropriate concentration and dispersed. The dispersion was dropped on a hydrophilized Si substrate and allowed to dry naturally. This was observed with a scanning electron microscope, and the concentration of the dispersion liquid was adjusted so that a sample in which the particles did not overlap with each other and the main plane of the tabular particles was oriented on the substrate surface could be prepared. After drying, the periphery was scraped off with a cutter except for a few mm square to obtain a measurement sample.

As an apparatus, ESCALAB 20 manufactured by VG was used.
Using 0-R, Ne ⁺ as an ion species, and an ion acceleration voltage of 1 kV, a range of 350 to 650 eV was measured. It was adjusted so that the sputter thickness in one scan was about 5 °. Ag (around 530 eV), Br (45
The area intensities of the peaks around 0 eV) and I (around 600 eV) were determined, and the I (Br + I) intensity ratio was plotted as a function of the thickness from the outermost surface of the particles.

The value of the I (Br + I) intensity ratio in the first scan is defined as the outermost surface measured value, and I (Br + I) at 20 ° is used.
I) Table 2 shows the ratio of the intensity ratio to the measured value of the outermost surface as attenuation.

<Evaluation of Sensitivity / Fog Density> Em-1 and each of the emulsions prepared above were subjected to chemical sensitization and spectral sensitization, and then coated samples were prepared and subjected to exposure, development, and property evaluation.

Further, Em-1A prepared as described above was used.
The same evaluation was performed by substituting .about.I. A specific method will be described below.

While keeping the emulsion Em-1 at 52 ° C., the following sensitizing dyes (SSD-1, SSD-2, SSD-3) were added. After aging for 20 minutes, sodium thiosulfate was added, and chloroauric acid and potassium thiocyanate were further added.
After ripening to obtain the optimum sensitivity / fog for each emulsion, 1-phenyl-5-mercaptotetrazole (AF-1) and 4-hydroxy-6-methyl-1,3,3
It was stabilized by adding 3a, 7-tetraazaindene (ST-1). The amount of sensitizing dye, sensitizer, and stabilizer added to each emulsion and the ripening time were set so that the sensitivity / fog relationship at 1/200 second exposure was optimized.

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A coated sample was prepared using Em-1 which had been subjected to the sensitization treatment, as a high-sensitivity green color-sensitive layer. That is, on a triacetyl cellulose film support provided with an undercoat layer, layers having the following compositions were sequentially formed from the support side to obtain a multilayer color photosensitive material sample. The addition amount is expressed in grams per 1 m ^2. However, silver halide and colloidal silver were converted to the amount of silver, and the sensitizing dye was shown as the number of moles per mole of silver in the same photosensitive layer.

First Layer (Antihalation Layer) Black Colloidal Silver 0.16 UV Absorber UV-1 0.3 Colored Magenta Coupler CM-1 0.123 Colored Cyan Coupler CC-1 0.044 High Boiling Solvent OIL-1 0.167 Gelatin 1.33 Second layer (intermediate layer) Stain inhibitor AS-1 0.16 High boiling point solvent OIL-1 0.20 Gelatin 0.69 Third layer (Low sensitivity red-sensitive layer) Silver halide a 0.20 silver iodobromide b 0.29 sensitizing dye SD-1 2.37 × 10 ^-5 sensitizing dye SD-4 1.2 × 10 ^-4 sensitizing dye SD-3 2.4 × ^10-4 sensitizing dye SD-4 2.4 × ^10-6 Cyan coupler C-1 0.32 Colored cyan coupler CC-1 0.038 High boiling point solvent OIL-2 0.28 Stain inhibitor AS-2 0.0. 002 Gelatin 0.73 4th layer Medium-speed red-sensitive layer) Silver iodobromide c 0.10 Silver iodobromide d 0.86 Sensitizing dye SD-1 4.5 × 10 ^-5 Sensitizing dye SD-2 2.3 × 10 ^-4 Sensitizing dye SD-3 4.5 × 10 ^-4 Cyan coupler C-2 0.52 Colored cyan coupler CC-1 0.06 DIR compound DI-1 0.047 High boiling point solvent OIL-2 0.46 Antifouling agent AS-2 0.004 Gelatin 1.30 Fifth layer (high-sensitivity red-sensitive layer) Silver iodobromide c 0.13 Silver iodobromide d 1.18 Sensitizing dye SD-1 3.0 × 10 ^{− 5} Sensitizing dye SD-2 1.5 × 10 ^-4 Sensitizing dye SD-3 3.0 × 10 ^-4 Cyan coupler C-2 0.047 Cyan coupler C-3 0.09 Colored cyan coupler CC-10 0.036 DIR compound DI-1 0.024 High boiling point solvent OIL-2 0.27 Stain inhibitor A -2 0.006 Gelatin 1.28 6th layer (intermediate layer) High boiling point solvent OIL-1 0.29 Stain inhibitor AS-1 0.23 Gelatin 1.00 7th layer (Low sensitivity green color sensitive layer) Silver iodobromide a 0.19 Silver iodobromide b 0.062 Sensitizing dye SD-4 3.6 × 10 ^-4 Sensitizing dye SD-5 3.6 × 10 ^-4 Magenta coupler M-1 0.18 Colored magenta coupler CM-1 0.033 High boiling solvent OIL-1 0.22 Stain inhibitor AS-2 0.002 Stain inhibitor AS-3 0.05 Gelatin 0.61 Eighth layer (intermediate layer) High boiling solvent OIL-1 0.26 Antifouling agent AS-1 0.054 Gelatin 0.80 Ninth layer (medium speed green color-sensitive layer) Silver iodobromide e 0.54 Silver iodobromide f 0.54 Sensitizing dye SD-6 3.7 × 10 ^-4 sensitizing dye SD-7 7.4 × 10 ^-5 sensitizing dye S D-8 5.0 × 10 ^-5 Magenta coupler M-1 0.17 Magenta coupler M-2 0.33 Colored magenta coupler CM-1 0.024 Colored magenta coupler CM-2 0.029 DIR compound DI-20 .024 DIR compound DI-3 0.005 High boiling point solvent OIL-1 0.73 Stain inhibitor AS-2 0.003 Stain inhibitor AS-3 0.035 Gelatin 1.80 10th layer (high sensitive green color sensitivity) Em-1 (Those subjected to sensitization treatment) 1.19 Magenta coupler M-1 0.065 Colored magenta coupler CM-1 0.022 Colored magenta coupler CM-2 0.026 DIR compound DI-20 0.003 DIR compound DI-3 0.003 High boiling solvent OIL-1 0.19 High boiling solvent OIL-2 0.43 Pollution prevention Agent AS-2 0.014 Antifouling agent AS-3 0.017 Gelatin 1.23 11th layer (yellow filter layer) Yellow colloidal silver 0.05 High boiling solvent OIL-1 0.18 Antifouling agent AS-10 .16 gelatin 1.00 12th layer (low-sensitivity blue-sensitive layer) silver iodobromide a 0.08 silver iodobromide b 0.22 silver iodobromide g 0.09 sensitizing dye SD-9 5 × 10 ^-4 sensitizing dye SD-10 2.5 × 10 ^-4 Yellow coupler Y-1 0.77 DIR compound DI-4 0.017 High boiling point solvent OIL-1 0.31 Stain inhibitor AS-20 0.002 gelatin 1.29 thirteenth layer (high-sensitivity blue-sensitive layer) silver iodobromide g 0.41 silver iodobromide h 0.61 sensitizing dye SD-9 4.4 × 10 ^-4 sensitizing dye SD-10 1.5 × 10 ^-4 yellow coupler Y-1 0.23 high-boiling solvent IL-1 0.10 Antifouling agent AS-2 0.004 Gelatin 1.20 14th layer (first protective layer) Silver iodobromide i 0.30 UV absorber UV-1 0.055 UV absorber UV- 2 0.110 High boiling point solvent OIL-2 0.30 Gelatin 1.32 15th layer (second protective layer) Polymer PM-1 0.15 Polymer PM-2 0.04 Slip agent WAX-1 0.02 Dye D -1 0.001 Gelatin 0.55 The characteristics of the above silver iodobromide are shown below (the average particle size is one side length of a cube of the same volume).

Emulsion No. Average grain size (μm) Average AgI content (mol%) Diameter / thickness ratio Silver iodobromide a 0.30 2.0 1.0 Silver iodobromide b 0.40 8.0 1.4 Silver iodobromide c 0.60 7.0 3.1 Silver iodobromide d 0.74 7.0 5.0 Silver iodobromide e 0.60 7.0 4.1 Silver iodobromide f 0.65 8.7 6. 5 Silver iodobromide g 0.65 8.0 1.4 Silver iodobromide h 1.00 8.0 2.0 2.0 Silver iodobromide i 0.05 2.0 1.0 In addition, coating aids SU-1, SU-2,
SU-3, dispersing aid SU-4, viscosity modifier V-1, stabilizers ST-1, ST-2, antifoggant AF-2 (polyvinylpyrrolidone, weight average molecular weight: 10,000), A
F-3 (polyvinylpyrrolidone, weight average molecular weight: 1,
100,000), inhibitors AF-4, AF-5, hardeners H-1, H-2 and preservative Ase-1.

The structures of the additional compounds are shown below.

SU-1: C ₈ F ₁₇ SO ₂ N (C ₃ H ₇ ) CH ₂ COOK SU-2: C ₈ F ₁₇ SO ₂ NH (CH ₂ ) ₃ N ⁺ (CH ₃ ) ₃
Br ^- SU-3: sodium di (2-ethylhexyl) sulfosuccinate SU-4: sodium tri-i-propylnaphthalenesulfonate ST-2: adenine AF-4: 1- (4-carboxyphenyl) -5-mercapto Tetrazole AF-5: 1- (3-acetamidophenyl) -5-mercaptotetrazole H-1: [(CH ₂ CHSO ₂ CH ₂ ) ₃ CCH ₂ SO ₂ C
H ₂ CH ₂ ] ₂ NCH ₂ CH ₂ SO ₃ K H-2: 2,4-dichloro-6-hydroxy-s-triazine sodium OIL-1: tricresyl phosphate OIL-2: di (2-ethylhexyl) Phthalate AS-1: 2,5-bis (1,1-dimethyl-4-hexyloxycarbonylbutyl) hydroquinone AS-2: Dodecyl gallate

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Immediately after the preparation of these samples, each sample was subjected to wedge exposure through a Toshiba glass filter (Y-48) using a light source having a color temperature of 5400 ° K, and developed according to the following processing steps.

(Processing step) Processing step Processing time Processing temperature Replenishment amount * Color development 3 minutes 15 seconds 38 ± 0.3 ° C. 780 ml Bleaching 45 seconds 38 ± 2.0 ° C. 150 ml Fixing 1 minute 30 seconds 38 ± 2. 0 ° C. 830 ml Stability 1 minute 38 ± 5.0 ° C. 830 ml Drying 1 minute 55 ± 5.0 ° C. * The replenishment amount is a value per 1 m ² of the photosensitive material.

The following color developing solutions, bleaching solutions, fixing solutions, stabilizing solutions and replenishers were used.

<Color developing solution and color developing replenishing solution> Developer replenishing solution Water 800 ml 800 ml Potassium carbonate 30 g 35 g Sodium hydrogen carbonate 2.5 g 3.0 g Potassium sulfite 3.0 g 5.0 g Sodium bromide 1.3 g 0.4 g Potassium iodide 1.2 mg-hydroxylamine sulfate 2.5 g 3.1 g sodium chloride 0.6 g-4-amino-3-methyl-N-ethyl-N-([beta] -hydroxylethyl) aniline sulfate 4.5 g 6 3.3 g diethylenetriaminepentaacetic acid 3.0 g 3.0 g potassium hydroxide 1.2 g 2.0 g Add water to make 1 liter, and add potassium hydroxide or 20%
The color developing solution is adjusted to pH 10.06 and the replenisher is adjusted to pH 10.18 using sulfuric acid.

<Bleaching Solution and Bleaching Replenisher> Bleaching Solution Replenisher Water 700 ml 700 ml 1,3-diaminopropanetetraacetic acid iron (III) ammonium 125 g 175 g ethylenediaminetetraacetic acid 2 g 2 g sodium nitrate 40 g 50 g ammonium bromide 150 g 200 g glacial acetic acid 40 g Add 56 g of water to make up to 1 liter, and adjust the pH of the bleaching solution to 4.4 and the pH of the replenishing solution to 4.0 using ammonia water or glacial acetic acid.

<Fixing Solution and Fixing Replenisher> Fixing Solution Replenisher Water 800 ml 800 ml Ammonium thiocyanate 120 g 150 g Ammonium thiosulfate 150 g 180 g Sodium sulfite 15 g 20 g Ethylenediaminetetraacetic acid 2 g 2 g Ammonia water or glacial acetic acid is used to adjust the pH of the fixing solution to 6.2.
Then, the pH of the replenisher is adjusted to 6.5, and then water is added to make 1 liter.

<Stabilizing Solution and Stabilizing Replenishing Solution> Water 900 ml p-octylphenol ethylene oxide 10 mol adduct 2.0 g dimethylolurea 0.5 g hexamethylenetetramine 0.2 g 1,2-benzoisothiazolin-3-one 0.1 g siloxane (UCC L-77) 0.1 g ammonia water 0.5 ml After adding water to make 1 liter, ammonia water or 50
Adjust to pH 8.5 with% sulfuric acid.

The sensitivity and fog density of each of the developed samples were measured using green light. The measuring method and conditions are shown below.

The density of the unexposed portion was defined as the fog density. The smaller the value of the fog density, the lower the fog, indicating that it is preferable. The sensitivity was obtained by calculating the reciprocal of the exposure amount giving a density of fog density + 0.2, and expressed as a relative value with the value of Em-1 being 100. The larger the value of the sensitivity is, the higher the sensitivity is, which indicates that it is preferable. The results are shown in Table 2 as normal development sensitivity and fog.

<< Storage property over time >> For each of the prepared coated samples, a sample (condition A) stored in a freezer (−20 ° C.) until immediately before exposure, and a temperature of 55 ° C. and a relative humidity of 80 immediately before exposure.
%, And the storage stability with time was evaluated in the same manner as in the evaluation of the sensitivity / fog density except that two samples (condition B) stored for 3 days were prepared.

The sensitivity variation width was defined as follows.

In the same manner as in the evaluation of the sensitivity / fog density, the density +
The reciprocal of the exposure amount that gives a density of 0.2 is determined, and the value of condition B is converted into a relative value with the value of condition A of each sample taken as 100. did. Further, the fluctuating range of fog density = (fog density of condition B-fog density of condition A).

The smaller the absolute value of both the sensitivity variation width and the fog variation width, the smaller the variation over time, which is preferable. The results are shown in Table 2 as short-term development sensitivity.

<< Processing Characteristics >> Sensitivity was evaluated in the same manner as the above-described evaluation of sensitivity / fog density, except that the development time was reduced to 1 minute and 45 seconds. Similar to the evaluation of the sensitivity / fog density, the sensitivity of Em-1 is set to 100 and the relative value is set. Therefore, the change in the sensitivity compared with the sensitivity obtained by development for 3 minutes 15 seconds is higher than that of Em-1. This indicates that the stability with respect to the fluctuation of the developing process is poor. Table 2 shows the results.

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[Table 2]

By using iodine, the iodine amount on the outermost surface can be improved and the attenuation can be increased with a smaller amount than in the case of adding silver iodide or potassium iodide. It is possible to improve both properties.

Example 3 In the same manner as in Example 2, the performance of emulsions having different aspect ratios was evaluated. Specifically, for the emulsions Em-2 and Em-3, a surface high iodine emulsion was prepared under the same conditions as in Em-1A of Example 2, and a surface high iodine emulsion Em- using Em-2 as the base emulsion was prepared. A surface high iodine emulsion Em-3A using 2A and Em-3 as base emulsions was obtained.

For Em-2A and Em-3A, the same evaluation as in Example 2 was performed. Table 3 shows the results.

It can be seen that the effects of the present invention are exhibited by an emulsion having an aspect ratio of 5 or more.

Example 4 In the same manner as in Example 2, the performance of emulsions having different monodispersities was evaluated. Specifically, for Em-4, a surface high iodine emulsion was prepared under the same conditions as Em-1A of Example 2 to obtain Em-4A.

For Em-4A, the same evaluation as in Example 2 was performed. Table 3 shows the results.

It can be seen that the effect of the present invention is more remarkable in a monodispersed emulsion.

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[Table 3]

Example 5 In the same manner as in Example 2, the performance of emulsions having different pAg when iodine was added was evaluated. Specifically, Em-1J to 1L were prepared for Em-1 by using the same method as Em-1A of Example 2 and changing only pAg at the time of adding iodine. The same evaluation as in Example 2 was performed for each emulsion. Table 4 shows the pAg conditions and the results.

[0142]

[Table 4]

The emulsion of the present invention is superior to the comparative emulsion in all evaluations.

FIG. 1 shows a measurement example of the relationship between the thickness from the particle surface and I / (Br + I) measured by ISS. Emulsion Em-1A of the present invention comprises comparative emulsions Em-1F and Em-1
The I / (Br + I) intensity ratio of the outermost surface is higher than that of G,
Also, it can be seen that the attenuation is large.

[0145]

According to the present invention, a silver halide photographic emulsion having high sensitivity, low fog, excellent storage stability over time, and excellent processing characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 shows an emulsion of the present invention (Em-1A) and a comparative emulsion (Em-1A).
-1F, Em-1G) with respect to the thickness (Å) from the surface of the silver halide grains by I / (Br +
Curve showing the relationship of I).

Claims (6)

[Claims] The present invention is characterized in that at least 50% of the total projected area is composed of tabular silver halide grains having an aspect ratio of 5 or more.
(I + Br) A silver halide photographic emulsion characterized in that the intensity ratio is 0.7 or more and the intensity ratio attenuates to 1/3 or less within 20 ° from the outermost surface. 2. Halogenation wherein at least 50% of the total projected area is composed of tabular silver halide grains having an aspect ratio of 5 or more, and the tabular grains have a high iodine uniform surface layer on the main plane of the grains. Silver photographic emulsion. 3. A silver halide photographic emulsion comprising tabular silver halide grains having an aspect ratio of 5 or more in at least 50% of the total projected area, and the surface of the emulsion grains has been subjected to an iodine oxidation treatment. 4. The silver halide photographic emulsion according to claim 1, wherein the silver halide grains constituting the silver halide photographic emulsion have a monodispersion of 25% or less in particle size distribution. 5. A method for producing a silver halide photographic emulsion comprising tabular silver halide grains having an aspect ratio of 5 or more in an area of 50% or more of a total projected area, wherein iodine is added at a pAg of 8.60 or less. 6. The method for producing a silver halide photographic emulsion according to claim 5, wherein the particle size distribution of silver halide grains constituting the silver halide photographic emulsion is 25% or less.