EP0367248A1

EP0367248A1 - Silver halide crystal grains and silver halide light-sensitive material

Info

Publication number: EP0367248A1
Application number: EP89120227A
Authority: EP
Inventors: Yukio Ohya; Syoji Matsuzaka
Original assignee: Konica Minolta Inc
Current assignee: Konica Minolta Inc
Priority date: 1988-10-31
Filing date: 1989-10-31
Publication date: 1990-05-09
Anticipated expiration: 2009-10-31
Also published as: DE68924395T2; DE68924395D1; EP0367248B1; JP2631720B2; JPH02120849A

Abstract

A silver halide grain having a new shape is prepared. The grain has protruded crystal plains attached to a basic crystal grain on each edge in parallel with a plain defined by 4 edges containing the center of the basic crystal grain to form brim-like plains. A silver halide emulsion containing the grain and a photographic material containing the emulsion as a photosensitive material are also disclosed. The photographic material shows high efficiency in sensitization, exposure and development.

Description

Field of the Invention

This invention relates to a silver halide crystal grains and to a silver halide light-sensitive material using the grains.

Background of the Invention

In recent years, the demands for silver halide photographic material have been getting more serious for such photographic characteristics as higher speed, more excellent graininess, higher image sharpness, lower fog-density, and sufficiently higher optical density.
A method of achieving photographic characteristics such as the above-mentioned high speed, excellent graininess, high image-sharpness, low fog-density, and sufficiently high covering-power is to improve the quantum efficiency of silver halides. According to the studies on the theoretical calculation of quantum efficiency, it is useful for improving quantum efficiency by a monodisperse type emulsion upon narrowing the graininess distribution. It may further be presumed that monodisperse type emulsions could be advantageous to efficiently achieve a high speed with keeping a low fog-density, in the so-called chemical sensitizing process of sensitizing silver halide emulsions.
For industrially manufacturing monodisperse type emulsions, it is required to satisfy the theoretical requirements for the control of a supplying rate of silver ions and halide ions to a reaction system and for a sufficient agitation, under the strict pAg and pH controls such as described in Japanese Patent Publication Open to Public Inspection -hereinafter referred to as Japanese Patent O.P.I. Publication- No. 54-48521(1979). The silver halide emulsions prepared under the above-mentioned conditions are comprised of the so-called regularly crystal grains in a cubic, octahedral, or tetradecahedral form having (100) and (111) faces in various proportions and it has been known that a high speed may be obtained when using such regular crystal grains.
On the other hand, as silver halide emulsions suitably applicable to high speed photographic films, silver iodobromide emulsions comprising polydisperse type twin-crystal grains have been known so far.
Also, Japanese Patent O.P.I. Publication No. 58-113927(1983) and so forth disclose silver iodobromide emulsions containing tabular twin-crystal grains.
The techniques on the above-mentioned twin-crystals contribute to a high sensitization. However, in these techniques, a crystal form or size is liable to become uneven and photographic characteristics may hardly be controlled accurately. Therefore, photographic reproducibility is a problem to these techniques.
As described above, the progress of studies on how to improve the photographic characteristics of silver halide light-sensitive materials is seen from the aspect of crystal forms. All the above-mentioned studies have been focused only on the externally protruding crystal forms, except the finely depressed portions of a twin-crystal or corroded image, and there has been no study at all on any crystals having distinctly large depressed portions on the crystal faces thereof.
The intersecting lines or points of a face having a depressed portion may presumably display the peculiarity of the effect concentrations on chemical sensitization, exposure, and development. It is, therefore, desired to make a further development of such crystals having the above-mentioned depressed portions.
The silver halide crystal grains, having the above-mentioned depressed portions are preferably of the regular crystals without having any peculiar points such as a lattice defect that is a substantial hindrance, other than the above-mentioned concentrated positions of the crystals.
However, in the system freely suspending therein the regular crystals having a specific crystal phase including particularly monodisperse type silver halide grains, crystal grains are grown up with being almost isogonally covered and there are, usually, a few occasions where the peculiarity such as a crystal habit, or an anisotropy may be presented.
On the other hand, it is difficult to precisely control the grains themselves, the chemical sensitization incidentally, and the photographic characteristics ultimately.

Summary of the Invention

It is an object of the invention to provide silver halide crystal grains capable of showing the effectiveness concentration to sensitization, exposure, and development.
Another object of the invention is to provide a novel silver halide light-sensitive material comprising an emulsion layer containing the above-mentioned silver halide crystal grains.
Silver halide grains of the present invention have calyxes, whereto protruded crystal pieces are attached in parallel with the 3 plane faces formed by 4 ridges respectively placed on one and the same plane face of a regular octahedron supposedly selected out of the regular crystals of the grains, and wherein the crystal pieces are combined at a right angles to each other.

Brief Description of the Drawings

Figure 1 is a schematic explanatory diagram illustrating a silver halide crystal of the invention; and
Figs. 2, 3 and 4 are each the electron-microscopic photographs of silver halide crystals of the invention.

Detailed Description of the Invention

Generally, among the crystal faces of silver halide crystal grains contained in a silver halide emulsion, the crystal faces having specific Miller indices are predominantly produced in correspondence with the densities of silver ions and halide ions arranged onto the crystal faces, lattice energies, surface energies, or growing conditions, so that specific crystal phases are given to the crystals. In addition, if the growing conditions of each crystal grain have a difference in grain-sizes, the sizes of the crystal faces will differ from each other so that each grain may produce a crystal habit, in spite of the fact that the crystal faces have one and the same Miller indices.
On the other hand, a plane face which will become an 'ultimate crystal face' to give a crystal phase to a crystal, such plane face has a minimum growth rate in the normal direction of the face, according to A Johnsen, 1910. Therefore, a crystal form having a specific crystal phase may also be given to silver halide crystals belonging to cubic system.
For example, a crystal form of a hexahedron - a cube - as a crystal phase, may be given to silver halide of cubic system by giving the silver halide the growing conditions in which the growing rate on the faces of the cube, i.e., the precipitation of silver ions and halide ions, is slower than that of crystal faces having the other Miller indices.
The crystal phase of host grains may be changed from octahedral silver halide crystal grains enclosed with (111) faces to hexahedral - cubic - grains, in the following manner. When silver halide is so added as to be precipitated under the growing conditions for inhibiting a cubic face (100) from growing, a tetradecahedron is temporarily produced in the form of a cubic octahedron i.e., a tetradecahedron in which 6 vertexes of an octahedron are cut off, while (111) faces are gradually contracted. Finally, the crystal grains have only the faces of a cube and, thereafter, the cubic crystal grains are getting larger as silver halide is further kept adding.
On the contrary, it is allowed to introduce cubic crystal grains into octahedral crystal grains, so as to serve as the host grains.
In the same manner as mentioned above, cubic crystal grains may also be introduced into octatriacontahedral crystal grains, for example. so as to serve as host grains. To be more concrete, when the precipitation of silver halide is kept going upon selection of growing conditions for which the growth of octatricontahedral crystal faces in the normal direction is slower than that of the faces having other Miller indices, octatricontahedral crystal faces are found first and then the host grains are finally occupied by the octatricontahedral crystal grains.
Besides the above, any crystal grains having the faces of hexatetracontahedron, modified rhombic tetracosahedron, or octahexacontahedron may be obtained as desired, when selecting the growing conditions for inhibiting the faces giving each crystal phase from growing.
The conditions for growing the above-mentioned silver halide grains having various crystal phases depend upon the diversified factors such as silver halide compositions, densities of ions arranged onto crystal faces, temperatures, lattices, surface energies, adsorptive substances, and silver halide solvents and, besides, growth modifiers for inhibiting silver halide from precipitating on crystal faces are also added to the factors.
As the growth modifiers, a number of compounds have been already known. Among them, those useful for silver halide for photographic use are found from among the dyes for photographic use such as cyanine dye having an adsorptivity to the surface of the silver halide, stabilizers such as azaindene and imidazole, and fog inhibitors. (Refer to the aforegiven Patent Publications, Japanese Patent Application No. 62-159280(1987), and so forth.
The conditions of preparing crystal grains, such as pAg, temperatures, the rates of adding silver halide, and the variations of the conditions are tested.
For example, the silver halide crystal grains are prepared at a pAg of 7 to 11.5 and a pH of 5.8 to 11.5 and, at the point of time when octahedral or tetradecahedral crystals are completed, cyanine dyes are added en bloc in an amount of 1 to 300 mg/AgX mol. When silver halide grains are kept growing further, the silver halide crystal grains are obtained so as to have crystal pieces each protruded in parallel with 3 plane faces (hereinafter called ridge faces) formed by the ridge lines of an octahedron and along the 3 plane faces combined together at a right angle to each other and also to have the depressed portions whose bottoms are the precedent crystal faces on 8 quadrants, respectively.
To the means of growing grains, a means of preparing core/shell type grains may appropriately be applied. It may also be considered that the portions of the crystals having calyxes are modified shell portions.
In the invention, it is allowed that the peculiarity of each grain may further be amplified by applying a metal compound at a suitable point of time in the course of producing and/or growing crystal grains.
When applying the above-mentioned regularly crystal grains to light-sensitive materials, it is preferable to make the grains monodispersible in a publicly known method.
Figure 1 is a schematic diagram showing a crystal grain of the invention having calyxes and a depressed surface; and Figs. 2 through 4 show each electron microscopic photographs thereof.
In Fig. 1, an octahedral crystal is taken as an example of host regular-crystals, in which (a-b), (b-c) and (c-a) are each the aforementioned ridge faces formed by axes a, b and c.
This figure shows only one quadrant made by 3 ridge faces. AB), (BC) and (CA) are each crystals having calyxes which are so protruded as to be in parallel with the above-mentioned ridge faces and so combined altogether as to be at a right angle to each other.
Fig. 2 shows an electron microscopic photograph of a crystal having calyxes, which was taken from almost the same angle as in the schematic diagram shown in Fig. 1.
Fig. 3 shows the same crystal as above, photographed from the direction of axis a, b or c
Fig. 4 shows the group of crystals having calyxes which are being grown.
It is inferred that the growth inhibition factors do not work in the direction of growing calyxes. It may possibly be considered that the growth of twin crystals still progress the growth of tabular-shaped calyxes in the above-mentioned direction in a uniformly conditioned suspension system, like an after-effect of desease.
The silver halide emulsions applicable to the light-sensitive materials of the invention are allowed to use any silver halides such as silver bromide, silver iodobromide, silver chlorobromide, and silver chloride, each of which may be applied to ordinary types of silver halide emulsions. Among these silver halides, silver bromide and silver iodobromide should particularly be preferable.
For the silver halide grains applicable to the silver halide emulsions, any of those prepared in an acidic process, a neutralizing processes or an ammoniacal process may be used. Those grains may be grown either continuously or with preparing seed grains stepwise. The both processes of preparing the seed grains and growing them may be the same with or the different from each other.
In preparing the silver halide emulsions, halide ions and silver ions may be mixed up together at the same time, or one of these ions may be mixed in a solution containing the other ions. Taking the critical growth rate of silver halide crystals into consideration and controlling the pH and pAg values in a mixing tank, the silver halide crystals may be grown by adding, gradually and at the same time, the halide ions and silver ions into the kettle. In this manner, it is possible to obtain silver halide grains having a regular crystal form and an almost uniform grain-size.
In the course of growing such silver halide grains, it is allowed to make present a publicly known silver halide solvent such as ammonium thioether, or thiourea.
In the courses of forming and/or growing silver halide grains, metal ions are added into the silver halide grains by making use of at least one metal salt selected from the group consisting of cadmium salts, zinc salts, lead salts, thallium salts, iridium salts, rhodium salts, iron salts, and the complex salts thereof, so that the metal element thereof may be added to the inside and/or on the surfaces of the grains. It is also allowed to endow the inside and/or the surfaces of the grains with reduction-sensitization nuclei, when they are put in a suitable reducible-atmosphere.
Any unnecessary soluble-salts contained in the silver halide emulsions applicable to the invention may either be remoced therefrom after completing the growth of the silver halide grains thereof or remain contained as they are. In the case of removing them, they may be removed in accordance with the method described in, for example, Research Disclosure, No. 17643, Paragraph II.
As the silver halide grains for the light-sensitive materials of the invention, those having a regular crystal form such as a cube, an octahedron, or a tetradecahedron and those having an irregular crystal form such as a spheric or tabular form may also be used in combination, as well as with the crystal grains having calyxes of the invention.
Silver halide grains may be used, provided the grain-size thereof is within the range of 0.05 to 30 µm and, preferably, 0.1 to 3.0 µm.
Any silver halide grains may be used in combination, regardless of their grain-size distributions. In other words, it does not care which type of emulsions is to be used; an emulsion having a wide grain-size distribution, (hereinafter called a polydispersive emulsion), or a monodispersive emulsion having a narrow grain-size distribution may either be used. The term, monodispersive(ness), used herein has a value of not more than 0.20 when the value is obtained from a standard deviation of a grain-size distribution divided by an average grain-size.
Such monodispersive emulsions may be used independently or in the mixture of several kinds thereof. It is also allowed to use polydispersive and monodispersive emulsions together in a mixture.
Such silver halide emulsions may further be used in a mixture of not less than 2 kinds thereof each separately prepared.
To the invention, a variety of chemical sensitization processes may be applied as they have usually been applied. Chalcogen sensitizers applicable to the chemical sensitization include, for example, sulfur, selenium and tellurium sensitizers. Among them, sulfur and selenium sensitizers are preferable for photographic use. For the sulfur sensitizers, any of the publicly known ones may be used. They include, for example, thiosulfate, allylthiocarbamide, thiourea, allylisothiocyanate, cystine, p-toluenethiosulfonate, and rhodanine. Besides the above, it is also allowed to use the sulfur sensitizers described in, for example, U.S. Patent Nos. 1,574,944, 2,410,689, 2,278,947, 2,728,668, 3,501,313, and 3,656,955; West German OLS Patent No. 1,422,869; and Japanese Patent O.P.I. Publication Nos. 56-24937(1981), and 55-45016(1980). Such sulfur sensitizers may be added in an amount sufficient to effectively enhancing the photosensitive speed of an emulsion. Such an amount thereof to be added may be varied over a considerably wide range under various condi tions such as pH values, temperatures, and the sizes of silver halide grains. As a rough standard, it is preferable to add in an amount within the range of the order of about 10⁻⁷ to about 10⁻¹ mols per mol of silver halide used.
The selenium sensitizers applicable to the invention include, for example, aliphatic isoselenocyanates such as allylisoselenocyanate, selenoureas, selenoketones, selenoamides, selenocarboxylic acids and the esters thereof, selenophosphates, and selenides such as diethyl selenide and diethyl diselenide. The typical examples thereof are given in U.S. Patent Nos. 1,574,944, 1,602,952, and 1,623,499.
Similar to the case of the sulfur sensitizers, the amounts thereof to be added are varied over a wide range. As a rough standard, they may preferably be added in an amount within the range of the order of about 10⁻⁷ to 10⁻¹ mols per mol of silver halide used.
The gold sensitizers applicable to the invention may have a gold valence of either +1 or +3 and they include, for example, a variety of gold compounds. The typical examples thereof include chloroaurates, potassium chloroaurate, auric trichloride, potassium auric thiocyanate, potassium iodoaurate, tetracyanoauric acid, ammonium aurothiocyanate, and pyridyl trichlorogold.
The amounts of such gold sensitizers to be added are varied under various conditions. A rough standard thereof is preferably within the range of about 10⁻⁷ to 10⁻¹ mols per mol of silver halide used.
Such gold sensitizers may be added at the same time when adding a sulfur or selenium sensitizer, or in the course of or after completion of a sulfur or selenium sensitization process.
When applying a sulfur or selenium sensitization and a gold sensitization to an emulsion in the invention, it is preferable that such emulsion is to have a pAg within the range of 5.0 to 10.0 and a pH, 5.0 to 9.0, respectively.
In the invention, a chemical sensitization process may be carried out in combination with another sensitization process using the salts or complex salts of the other noble metals such as platinum, palladium, iridium, and rhodium.
Besides the above, the comlexes of Rh, Pd, Ir, Pt may effectively be used as the compounds for both releasing gold ions from gold-gelatinate and accelerating the adsorption of gold ions to silver halide grains.
Such compounds include, typically, (NH₄)₂[PtCl₄], (NH₄)₂[PdCl₄], K₃[IrBr₆], and (NH₄)₃[RhCl₆]12H₂O. Among them, ammonium II tetrachloropalladate (NH₄)₂PdCl₄ is most preferable.
The amount thereof to be added to a gold sensitizer is preferably within the range of 10 to 100 times as much as the gold sensitizer used, in terms of a stoichiometric ratio, i.e., a mol-ratio.
Such a compound may be added at any points of time when starting a chemical sensitization, in the course thereof, or in the course of carrying out any following steps after completing the chemical sensitization. It is to be added, preferably, in the course of carrying out the chemical sensitization and, more preferably, at the same time when, before, or after adding the gold sensitizer.
To the invention, it is further allowed to apply a reduction-sensitization in combination. To the reducing agents, there is no special limitation. They include, for example, stannous chloride, thiourea dioxide, hydrazine derivative, and polyamine, each of which has been known.
Such reduction-sensitization may be carried out in the course of growing silver halide grains and, preferably, after completing the chalcogen, gold and noble-metal sensitization.
Further in a chemical sensitizing process, it is also allowed to make coexist a compound having a nitrogen-containing heterocyclic ring or, more preferably, an azaindene ring.
The amounts of such nitrogen-containing heterocyclic compounds to be added may be varied over a wide range depending on the conditions such as the sizes and compositions of emulsion gains and chemical sensitzation requirements. It is, however, preferable to add them in such an amount as is capable of forming one of from monomolecular layer to 10-molecular layer on the surfaces of silver halide grains.
The amounts thereof may also be increased or reduced in such a manner that the equilibrium state of an adsorption is controlled by varying a pH and/or a temperature when carrying out a sensitization. It is further allowed to add not less than two kinds of the above-mentioned compounds to make a total amount thereof to be within the above-mentioned range.
The above-mentioned compounds are also allowed to add into a photographic emulsion in such a manner that the compound is dissolved in a suitable solvent such as water or an aqueous alkaline solution, which does not harmfully affect the emulsion, and is then added in the form of a solution to the emulsion. The compounds may preferably be added thereto before or at the same time when adding a sulfur or selenium sensitizer for chemical sensitization. Besides, a gold sensitizer may be added in the course of or after completing a sulfur or selenium sensitization.
The above-mentioned silver halide grains may also be optically sensitized to a desired spectral wavelength region, by making use of a sensitizing dye.
To the silver halide emulsions, the additives such as an antifoggant and a stabilizer may be added.
As a binder for such emulsions, gelatin may advantageously be used. Emulsion layers and other hydrophilic colloidal layers may be hardened and are allowed to contain a plasticizer and the dispersion of a water-insoluble or hardly soluble synthetic polymer, that is so-called a latex.
Into the emulsion layers of a color photographic light-sensitive material, couplers are added. Besides, it is also allowed to use thereinto a colored coupler having a color-compensation effect, a competing coupler, and a compound capable of releasing a photographically useful fragment such as a development accelerator, a bleach accelerator, a developing agent, a silver halide solvent, a color toner, a layer hardener, a foggant, an antifoggant, a chemical sensitizer, a spectral sensitizer, and a desenstizer, upon coupling reaction with the oxidized product of a developing agent.
To light-sensitive materials, it is allowed to provide auxiliary layers such as a filter layer, an antihalation layer, and antiirradiation layer. Into such layers and/or emulsion layers, it is also allowed to contain a dye capable of discharging from the light-sensitive material or being bleached, in the course of developing the light-sensitive material.
Such light-sensitive material is allowed to contain a formalin scavenger, a fluorescent brightening agent, a matting agent, a lubricant, an image stabilizer, a surfactant, a color-fog inhibitor, a development accelerator, a development retarder, and a bleach accelerator.
As the supports of such light-sensitive materials, a sheet of paper laminated with polyethylene or the like, a polyethyleneterephthalate film, a baryta paper, and cellulose triacetate film may be used.
In the case of obtaining a dye image by the use of the light-sensitive material of the invention, color photographic processes which have been commonly known may be carried out after exposing the light-sensitive materials to light.

Examples

Next, the invention will be detailed with reference to the following examples.
In advance to the examples, the following emulsions will be detailed for the comparison purpose.

Comparative Example 1

A Comparative Emulsion EM-1 was prepared by the use of the following 7 kinds of solutions.

Solution B

Ossein gelatin 67.6 g

KBr 845.4 g

Add distilled water to make 3383 cc

Solution C

AgNO₃ 1177 g

A 28% aqueous ammonia 960 ml

Add distilled water to make 3299 ml

Solution D

An aqueous 50% KBr solution An amount required to adjust a pAg

Solution E

An aqueous 50% acetic acid solution An amount required to adjust a pH
Solutions B and C were added into Solution A by keeping a temperature of 40°C and spending a time for 73.7 minutes in a double-jet precipitation method with a mixing stirrer described in Japanese Patent O.P.I. Publication Nos. 57-92523(1982) and 57-92524(1982).
In the course of the double-jet precipitation, the pAg and pH values of the emulsion and the rates of adding Solutions B and C were controlled as shown in Table-1. The pAg and pH values of the emulsion were controlled by adjusting the flow rates of Solutions D and E by the use of a variable-flow roller tube pump. Two minutes after completing the addition of Solution C, the pH value of the emulsion was adjusted to be 6.0 with Solution E.
Next, the resulting emulsion was desalted and washed in an ordinary method and was then dispersed in an aqueous solution containing ossein gelatin.

In an electron-microscopic observation, it was proved that the resulting emulsion was a high-grade octahedral monodisperse type emulsion having an average grain-size of 1.0 µm and a variation coefficient of 12% in grain-size distribution.

Table-1

	Adding Rate of Solution
Time (min.)	B	C	pAg	pH
0	6.4	6.5	9.10	9.0
12.2	16.1	16.4	9.10	8.96
28.5	54.7	55.7	9.10	8.80
29.6	59.3	59.4	9.12	8.78
43.2	67.7	63.9	9.68	8.50
45.8	67.2	62.4	9.76	8.45
48.5	66.2	60.2	9.84	8.40
51.9	63.6	56.1	9.94	8.34
54.3	52.6	52.6	10.00	8.30
63.1	51.8	51.6	10.00	8.16
73.7	47.7	47.5	10.00	8.0

Example 1

Emulsion EM-2 of the invention, which contains silver halide crystals with calyxes, was prepared in the same manner as in Comparative Example 1, except that the following two kinds of aqueous solutions containing the photosensitive dyes were added 43.2 minutes after starting the addition of the solutions.

An aqueous 0.2% methanol solution containing photosensitive dye I 736 ml

An aqueous 0.2% methanol solution containing photosensitive dye II 864 ml

Photosensitive dye I

Photosensitive dye II

Example 2

Next, an example of silver halide color light-sensitive materials to which the emulsions of the invention were used will be given below.
In this example, the descriptions will be made about a case where the invention was applied to a sample of the light-sensitive materials comprising two layers in total, namely, one for an emulsion layer containing a coupler and another for a protective layer.
In the sample, a pyrazolotriazole magenta coupler represented by the following Formula was used.
As a high boiling solvent for dissolving the coupler, di-t-nonylphenol DNP was used. The coupler was protect-dispersed in an ordianry method.
Next, the silver iodobromide emulsions EM-1 and EM-2 given in the foregoing Comparative Example and Example were each subjected to an optimum chemical sensitization, by the use of an unstable sulfur compound and a gold salt. Comparative EM-1 was color sensitized to green by adding the photosensitive dyes I and II which were used in Example 1 in the same amounts each as that of EM-2, when EM-1 was chemically sensitized.
Layer 1 ... A high speed green-sensitive emulsion layer conyaining 1.8 g of a silver iodobromide emulsion which was chemically and color sensitized as described above, 1.9 g of gelatin, and 0.06 g of a di-t-nonylphenol DNP dispersion in which 0.20 g of magenta coupler and 0.049 g of colored magenta coupler were dissolved and
Layer 2 ... A yellow filter layer containing 0.15 g of yellow colloidal silver, 0.11 g of dibutyl terephthalater DBP dispersion in which 0.2 g of an antistaining agent, and 1.5 g of gelatin,
Besides the above-mentioned compositions, a gelatin hardener and a surfactant were also added Into each of the above-mentioned layers.
The resulting samples were exposed to green light through a wedge in an ordinary method, and were then subjected to a sensitometry, respectively.

The exposed samples were treated in the following processing steps.

[Processing steps]
Color developing	3 min. 15 sec.
Bleaching	6 min. 30 sec.
Washing	3 min. 15 sec.
Fixing	6 min. 30 sec.
Washing	3 min. 15 sec.
Stabilizing	1 min. 30 sec.
Drying

The compositions of the rocessing solutions used in the above-mentioned processing steps will be given below.

[Color Developer]
4-amino-3-methyl-N-(ß-hydroxyethyl)aniline sulfate	4.57 g
Anhydrous sodium sulfite	4.25 g
Hydroxylamine 1/2 sulfate	2.0 g
Anhydrous potassium carbonate	7.5 g
Sodium bromide	1.3 g
Trisodium nitrilotriacetate, monohydrate	2.5 g
Potassium hydroxide	1.0 g
Add water to make	1 liter

[Bleaching Solution]
Iron-ammonium ethylenediaminetetraacetate	100.0 g
Diammonium ethylenediaminetetraacetate	10.0 g
Ammonium bromide	150.0 g
Glacial acetic acid	10.0 ml
Add water to make	1 liter
Adjust pH with aqueous ammonia to be	pH 6.0

[Fixing Solution]
Ammonium thiosulfate	175.0 g
Anhydrous ammonium sulfite	8.6 g
Sodium metasulfite	2.3 g
Add water to make	1 liter
Adjust pH with acetic acid to be	pH 6.0

[Stabilizer]
Formalin, in an aqueous 37% solution	1.5 ml
Konidux, manufactured by Konica Corp.	7.5 ml
Add water to make	1 liter

The samples thus developed were subjected to sensitometry by making use of green rays of light.
Fog ... This is expressed by a so-called minimum optical density value given onto a characteristic curve obtained in a sensitometry. It is not preferable when this value is relatively great, because the greater this value is, the higher a fog density will be.
Speed ... This is expressed by the reciprocal number of an antilog exposure giving an optical density of fog + 0.1 on a characteristic curve. In the table showing the results of the examples, the speed values thereof are given in relation to the speed of the comparative emulsion that was regarded as a value of 100 when the comparative emulsion was ordinarily exposed to light for an exposure time of 1/500 sec. It is preferable when this value is relatively great, because the greater this value is, the faster the speeds will be.
Substantial density ... This is expressed by the value deducted a value of a minimum density from that of a maximum density on a characteristic curve. In Table-2, the values are indicated in relation to the substantial density value of the comparative emulsion that was regarded as a value of 100. It is preferable when the value is relatively great, the higher the development rate will be.
The results thereof are shown in Table-2. Table-2

Sample No. Emulsions Speed Fog Substantial density

1 EM-1 -for Comparison- 100 0.28 100

2 EM-2 -of Invention- 128 0.24 135
As is obvious from the results shown in Table-2 above, it was proved the fact that the emulsion of the invention has a few fogs and is high in speed, substantial density, and development activity.

Example 3

Preparation of multilayered type color light-sensitive materials - herinafter called multilayered samples -

By making use of the chemically and color sensitized silver iodobromide emulsions which were the same as those used for preparing the aforementioned monochromatically sensitive coated samples, nine-layered color light-sensitive materials each having three kinds of light-sensitive layers, namely blue-, green- and red-sensitive layers, were prepared. In the preparation thereof, the chemically and color sensitized EM-1 and EM-2 emulsions were each changed only in the high speed green-sensitive layer that was the 5th layer, and quite the common emulsions were used in the other light-sensitive layers of each sample.
The samples were prepared by coating the following layers in order over a transparent support made of a subbed cellulose triacetate film bearing thereon an antihalation layer containing 0.40 g of black colloidal silver and 3.0 g of gelatin.
In all the following examples, the quantities of the composites in the light-sensitive materials will be expressed in terms of a quantity per sq. meter, and the amounts of silver halide emulsions and colloidal silver will be expressed in terms of the silver contents thereof.

Layer 1 ... A low speed red-sensitive emulsion layer containing 1.4 g of a red-sensitized low speed silver iodobromide emulsion having a silver iodide content of 7 mol% 1.2 g of gelatin, and 0.65 g of tricresyl phosphate -TCP- dispersion which was dissolved therein with 0.8 g of 1-hydroxy-4-(β-methoxyethyl aminocarbonylmethoxy)-N-[δ-(2,4-di-t-amylphenoxy)butyl)-2-naphthoamide [hereinafter referred to as C-1], 0.075 g of disodium 1-hydroxy-4-[4-(1-hydroxy -δ-acetamido-3,6-disulfo-2-naphthylazo)phenoxy]-N-[δ-(2,4-di-t-amylphenoxy)butyl-2-naphthamide [hereinafter referred to as colored cyan coupler CC-1], 0.015 g of 1-hydroxy-2-[δ-(2,4-di-t-amylphenoxy)butyl]naphthoamide, and 0.07 g of 4-octadecylsuccinimido-2-(1-phenyl-5-tetrazolylthio)-1-indanone [hereinafter referred to as DIR compound D-1.
Layer 2 ... A high speed red-sensitive emulsion layer containing 1.3 g of a high speed red-sensitive silver iodobromide emulsion, 1.2 g of gelatin, and 0.23 g of TCP dispersion in which 0.21 g of cyan coupler C-1 and 0.02 g of colored cyan coupler CC-1 were dissolved.
Layer 3 ... An interlayer containing 0.04 g of dibutyl phthalate DBP dispersion in which 0.007 g of 2,5-di-t-octyl hydroquinone (hereinafter referred to as an antistaining agent HQ-1 was dissolved, and 0.8 g of gelatin.
Layer 4 ... A low speed green-sensitive emulsion layer containing 0.80 g of a green-sensitized low speed silver iodobromide emulsion having a silver iodide content of 6 mol%, 2.2 g of gelatin, and 0.95 g of TCP dispersion which was dissolved therein with 0.8 g of 1-(2,4,6-trichlorophenyl)3-[3-(2,4-di-t-amylphenoxyacetamido)benzamido]-5-pyrazolone 0.15 g of 1-(2,4,6-trichlorophenyl)-4-(1-naphthylazo)-3-(2- chloro-5-octadecenylsuccinimidoanilino)-5-pyrazolone (hereinafter referred to as a colored magenta coupler CM-1, and 0.016 g of a DIR compound D-1.
Layer 5 ... A high speed green-sensitive emulsion layer containing 1.8 g of the aforementioned chemically and green-sensitized high speed silver iodobromide emulsions EM-1 and EM-2, 1.9 g of gelatin, and 0.06 g of a DNP dispersion in which 0.20 g of pyrazolotriazole coupler represented by the aforegiven Formula A and 0.049 g of colored magenta coupler CM-1 were dissolved.
Layer 6 ... A yellow filter layer containing 0.15 g of yellow colloidal silver, 0.11 g of a DBP dispersion in which 0.2 g of antistaining agent HQ-1 was dissolved, and 1.5 g of gelatin.
Layer 7 ... A low speed blue-sensitive emulsion layer containing 0.2 g of a blue-sensitized low speed silver iodobromide emulsion having a silver iodide content of 4 mol%, 1.9 g of gelatin, and 0.6 g of a TCP dispersion which was dissolved therein with 1.5 g of α-pivaloyl-α-(1-benzyl-2-phenyl-3,5-dioxoimidazolidine-4-yl)-2′-chloro-5′-[α-dodecyloxycarbonyl)ethoxycarbonyl]acetoanilide (hereinafter referred to as Y-1).
Layer 8 ... A high speed blue-sensitive emulsion layer containing 1.0 g of a blue-sensitized high speed silver iodobromide emulsion, 1.5 g of gelatin, and 0.65 g of a TCP dispersion in which 1.30 g of yellow coupler Y-1 was dissolved.
Layer 9 ... A protective layer containing 2.3 g of gelatin.

[Sensitometry]

The multilayered color light-sensitive materials thus prepared were exposed to light through a white wedge in the ordinary method and processed in the aforementioned processing steps. The resulting light-sensitive materials were each subjected to sensitometry, so that the green sensitivities were obtained. The definitions of 'Sensitivity' is the same as that in the case of the aforementioned monochromatically sensitive coated samples.
The results thereof are shown in Table-3. Table-2

Sample No. Emulsions Speed Fog Substantial density

3 EM-1 -for Comparison- 100 0.30 100

4 EM-2 -of Invention- 140 0.26 112
As is obvious from the results shown in Table-3 above, it was proved the fact that the emulsion of the invention has a few fogs and is high in speed, substantial density, and development activity. As is proved above, even in the samples having a multilayer arrangements, the advantages of the invention can be enjoyed, as well as in Example 1.

Claims

1. A silver halide grain having protruded crystal plains attached to a basic crystal grain on each edge in parallel with a plain defined by 4 edges containing the center of the basic crystal grain to form brim-like plains.

2. A silver halide grain as claimed in claim 1, wherein the basic crystal grain is octahedron.

3. A silver halide grain as claimed in claim 1, wherein the silver halide is silver bromide or silver iodebromide.

4. A silver halide emulsion comprising sisilver halide grains having protruded crystal plains attached to a basic crystal grain on each edge in parallel with a plain defined by 4 edges containing the center of the basic crystal grain to form brim-like plains.

5. A silver halide emulsion as claimed in claim 4, wherein the silver halide emulsion is monodispersed grain size distribution emulsion.

6. A silver halide emulsion as claimed in claim 4, wherein average of grain size of the silver halide emulsion is 0.1 to 3.0µm.

7. A silver halide photographic material comprising a silver halide emulsion layer which comprises silver halide grains having protruded crystal plains attached to a basic crystal grain on each edge in parallel with a plain defined by 4 edges containing the center of the basic crystal grain to form brim-like plains.

8. A silver halide photographic material as claimed in claim 7, wherein average of grain size of the silver halide emulsion is 0.1 to 3.0µm.

9. A silver halide photographic material as claimed in claim 7, wherein the silver halide emulson is chemically sensitized.

10. A silver halide photographic material as claimed in claim 7, wherein the silver halide emulson is optically sensitized.