JPH0452636A - Silver halide emulsion having high sensitivity and good developability - Google Patents

Abstract

PURPOSE:To enhance the sensitivity and developability of a photosensitive material by incorporating silver halide particles having a specific crystal form into the emulsion. CONSTITUTION:The silver halide particles in which the central part of at least one face of the 111 faces of an octahedron or 14-faced body builds up and this built-up part occupies >=50% of the area of these faces are incorporated into this emulsion. The building up of the central part of the 111 faces refers to the building up of the face in the position which is not the side edge part so that the wide projecting parts of various shapes exist. The formation and/or growth of the silver halide particles having the shape of the crystal of the octahedron or 14-faced body is executed at the prescribed value or below of the iodide content on the extreme surface. Further, the phase having the iodide content higher than the iodide content in the extreme surface of these particles is grown, by which the emulsion is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a silver halide emulsion, and particularly to a silver halide emulsion with high sensitivity and good developability.

[Conventional technology]

In recent years, demands on silver halide emulsions for photography have become increasingly strict, with increasingly high standards required for photographic performance such as high sensitivity, excellent graininess, high sharpness, low fog density, and sufficiently high optical density. is being done. In addition, it is required that the developability is good.

Among these, various techniques have been proposed in an attempt to provide high-sensitivity emulsions. For example, silver iodobromide emulsions having a silver iodide content of 10 mol % or less are well known. In addition, conventional methods for preparing these emulsions include pH conditions such as the ammonia method, neutral method, and acidic method, PAg
As a method of controlling conditions and a mixing method, a single jet method, a double jet method, etc. are known.

Based on these known techniques, technical means have been elaborately studied and put into practical use for the purpose of achieving high sensitivity, improved graininess, high sharpness, and low capri. In particular, research has been carried out on silver bromide and silver iodobromide emulsions in which not only the crystal phase and grain size distribution but also the concentration distribution of silver iodide within each silver halide grain is controlled.

Means for achieving photographic performance such as high frequency range, excellent graininess, high sharpness, low fog density, and sufficiently high covering power as described above, especially the most orthodox method for increasing sensitivity. The purpose is to improve the quantum efficiency of silver halide. For this purpose, knowledge of solid state physics is actively incorporated. According to research that theoretically calculated quantum efficiency, narrowing the particle size distribution to create a monodisperse emulsion is effective in improving quantum efficiency.

In addition, it is inferred that monodisperse emulsions are advantageous in order to efficiently achieve high sensitivity while maintaining low fog in a process called chemical sensitization in which silver halide emulsions are sensitized.

For industrial monodisperse emulsion preparation, JP-A-54-4852
As described in No. 1, under strict control of PAg and pH, control of the theoretically determined supply rate of silver ions and halide ions to the reaction system, and sufficient stirring conditions are required. Ru. Silver halide emulsions produced under these conditions are made from so-called normal crystal grains having cubic, octahedral, or tetradecahedral (100) and (111) planes in various proportions. Become. It is known that such normal crystal particles can increase sensitivity.

Furthermore, as silver halide grains capable of obtaining high sensitivity, silver iodobromide grains having excellent photographic properties and having (110) planes are disclosed in Japanese Patent Application Laid-open Nos. 61-35440 and 60-222842, respectively. In addition, in Japanese Patent Publication No. 55-42737, there is a rhombus with (110) face as a product with less fog.
Photographic emulsions containing dihedral silver chlorobromide grains are disclosed.

On the other hand, JP-A No. 61-83531 discloses silver bromide and silver iodobromide grains having a crystal plane with a ridge line in the center of the (110) plane, which can further improve sensitivity. It is shown. This crystal plane is considered to be a very high-order crystal plane, and its characteristics have been described in
No. 83531.

The crystal plane is expressed as (nnl), and examples such as the (331) plane are shown.

Other aspects are described in JP-A Nos. 62-124551, 62-124550, and 62-123447.

On the other hand, silver iodobromide emulsions comprising polydisperse twin crystal grains have been known as silver halide emulsions suitable for high-speed photographic films.

Moreover, silver iodobromide emulsions containing oblate twin grains are disclosed in Japanese Patent Application Laid-open No. 58-113927 and others.

On the other hand, in the field of chemical sensitization, the chemical sensitization reaction for normal crystals is highly dependent on the crystal phase.
It is known that since more sulfur sensitizing nuclei are formed on the (111) plane than on the (100) plane, latent image formation becomes dispersive and inefficient, resulting in poor exacerbation efficiency. Therefore, it has been considered disadvantageous or difficult to put silver halide grains having the above-mentioned (111) plane into practical use.

For example, Japanese Patent Application Laid-open No. 50-63914 and German patent application (
OLS) No. 2,419,798, silver bromide containing molybdenum
It is stated that the sensitivity increases when a hydroxytetrazaindene compound is added after sulfur sensitization of a monodisperse silver halide grain emulsion of cubic grains with a ratio of 80% or more, and the parenthetical publication states that It is also noted that for crystal shapes other than cubic, for example, octahedral grains substantially surrounded by (111) planes, the sensitivity actually decreases, but even if it increases, the extent of the increase is small.

As mentioned above, research from the viewpoint of crystal morphology is progressing at an impressive rate toward improving the photographic properties of silver halide photosensitive materials, but most of the research, with the exception of minute concave portions of twins or concave portions of eroded images, is progressing. There is little research on crystals that are outwardly convex and have clearly large unevenness on the crystal plane.

As for what is disclosed as a publicly known technique, Japanese Unexamined Patent Publication No. 5
No. 8-106532 describes a silver halide emulsion having a depression in the center of the (111) plane of an octahedral or tetradecahedral crystal. Further, JP-A-61-75337 discloses a silver halide emulsion containing silver halide grains having hollow conductive portions from the surface toward the inside. In addition, as tabular grains other than normal crystals, JP-A-63
Japanese Patent No. 311244 discloses a silver halide emulsion consisting of silver halide grains having a depression or space in the center of the main surface of a tabular grain consisting of opposing parallel main planes consisting of (111) planes. has been done.

All of them aim to concentrate latent images or development starting points in the depressions or spaces on the silver halide grains, thereby increasing sensitivity, improving storage stability, and improving developability.

However, all of them involve a step of dissolving and removing a part of the formed silver halide grains using a silver halide solvent. The unevenness on the particle surface also increased, and sufficient effects were not obtained in terms of concentration of latent images and concentration of development starting points.

Also, JP-A-63-244030, JP-A-63-26
No. 4739, JP-A-62-89949, JP-A-62-
No. 269948, JP-A-63-38930, JP-A-1
Patent No. 179140 discloses a silver halide emulsion in which silver halide grains have silver halide protrusions on their surfaces. But all of them are
The protrusions occupy only a small portion of the area of the surface, and the protrusions may be made of silver chlorobromide that does not contain silver iodide, or the protrusions may be made of silver chloride or silver halide. A very large number of silver oxide protrusions were present, and a sufficient effect of increasing sensitivity could not be obtained.

As mentioned above, with the conventional technology, it is insufficient to achieve high sensitivity and improve development performance by concentrating the latent image and development starting point.
Research from the perspective of crystal morphology using methods other than those described above has been awaited.

[Purpose of the invention]

The present invention was made against the above background, and an object of the present invention is to provide a silver halide emulsion that achieves high sensitivity and improved developability through research from the aspect of crystal morphology as described above.

[Structure of the invention]

As a result of intensive research, the present inventors have found that the above-mentioned object of the present invention is such that the center of at least one of the (111) planes of an octahedral or tetradecahedral crystal is raised, and the raised part is a linear plane. They have discovered that this can be achieved by using a silver halide emulsion containing silver halide grains that occupy 50% or more of the area, and have completed the present invention.

In the present invention, the center of the r (111) plane is raised.
This means that the surface bulges near the center of the (111) surface (it doesn't have to be exactly the center, but should be at a position that can almost act as the center), that is, it is not the edge, and the surface has a wide variety of shapes. This refers to the presence of a protrusion (occupying 50% or more of the area). The raised portion is often rectangular, but it changes depending on the adjustment conditions. The diameter of the raised portion (represented by the diameter of a circle when the projected area of the raised portion is converted into a circle) varies depending on the diameter of the parent octahedral or tetradecahedral particle, but is preferably 0.
005 um to 20 am, more preferably 0.005 um to 20 am.
005 μm to 2.0 μm. The height of the protrusion is not perpendicular to the (111) plane of the cubic particle, but 0.00 in the 111> direction.
It is preferably 5 μm or more, more preferably 0.02 μm or more.

For example, emulsion E, which is an example of the emulsion of the present invention which will be described in detail later,
Regarding the grain structure example shown in the photograph in Figure 1 showing the grain structure of M-1, each face of the (111) face of the octahedron is a triangle (strictly speaking, a triangle with each vertex cut off). It has a structure in which a triangular raised portion, which is approximately concentric with the triangle and slightly smaller than the triangle, is formed on each surface.

The present invention will be explained in more detail below.

In general, the crystal planes of silver halide crystal grains contained in silver halide emulsions have different density, lattice energy, surface energy, or growth conditions of silver ions and halide ions arranged on the plane. , crystal planes with specific Miller indices are dominantly expressed, giving the crystal a specific crystal phase. Furthermore, when there is a difference in the growth conditions surrounding each crystal grain on a grain size scale, the grains will have different crystal habits even though they have the same Miller index.

On the other hand, the plane that becomes the ultimate crystal plane that gives the crystal a crystalline phase is the plane that has the minimum growth rate in the direction normal to that plane.'' (
A. Johnsen, 1910) Therefore, by selecting the growth conditions, even silver halide crystals belonging to the cubic system can be given a crystal form having a predetermined crystal phase.

For example, in order to give cubic silver halide a hexahedral (cubic) crystalline phase, the growth rate on cubic planes, that is, the deposition of silver ions and halide ions, is slower than on crystal planes with other Miller indices. As long as the conditions are given.

Furthermore, when changing the crystal phase from octahedral silver halide crystal grains surrounded by (111) planes to hexahedral (cubic) host grains, growth conditions are provided to suppress the growth of cubic (100) planes. As silver is further precipitated, a cuboctahedron, that is, a tetradecahedron in which the six vertices of the octahedron have been shaved off, appears in the middle, and the (111) plane gradually degenerates until it becomes a cubic octahedron with only six vertices removed. The crystal grains become crystal grains, and thereafter the cubic crystal grains enlarge as silver halide is added.

Conversely, cubic crystal grains can also be used as host particles to lead to octahedral crystal grains.

Similarly, cubic crystal grains can also be introduced as host grains, for example trioctahedral crystal grains.

In other words, if silver halide precipitation is continued by selecting growth conditions in which growth in the normal direction of trioctahedral crystal planes is slower than planes of other Miller indices, trioctahedral crystal planes will first be recognized, and then Eventually, the host grains are occupied by trioctahedral crystal faces.

Desired crystal grains can also be obtained with other crystal grains having tetrahexahedral, rhomboid icosahedral, and hippophedral crystal faces by selecting growth conditions that suppress the growth of the faces that give each crystal phase.

The growth conditions for the silver halide grains having various crystal phases are as follows:
Deposition of silver halide on crystal surfaces is influenced by a wide variety of factors such as silver halide composition, density of ions arranged on crystal planes, temperature, lattice or surface energy, adsorbate, silver halide solvent, etc. A growth modifier is added as a factor to retard the process.

Many compounds are already known as growth regulators, and for photographic silver halide, there are photographic dyes such as cyanine dyes that have adsorption properties on the surface, stabilizers such as azaindene and imidazole, and fog suppressants. Some useful agents are known (see the above-mentioned Disclosure Patent Publication, Japanese Patent Application No. 62-159).
No. 280, etc.).

However, at present, there is a lack of theory that relates the various factors that influence crystal growth as described above and the crystal form produced, and in particular, there is a lack of theory in the unexplored technical field of producing surfaces with raised portions on crystal grains as in the present invention. There is no proof, and we have no choice but to search for ways to realize the intended crystal form through trial and error.

The emulsion of the present invention has (111) octahedral or tetradecahedral crystals.
at least one of the faces (preferably (111
Although it includes silver halide grains having a raised portion at the center of all surfaces (), it is not necessarily easy to create such grain crystals. In order to obtain such grain crystals, the present inventor conducted trial and error regarding the preparation conditions of crystal grains, such as 1) Ag, temperature or silver halide addition rate, and fluctuation of conditions, and achieved the method of the present invention as follows. It has been found that an emulsion can be obtained. That is, for example, the following manufacturing method can be mentioned.

Silver halide grains having an octahedral or tetradecahedral crystal shape are produced and/or grown, with the outermost surface having a normal content of 10 mol % or less. Furthermore, it is preferably 10 mol% or more, more preferably 1 mol % or more than the legal content on the outermost surface of the particles
A phase with a high legal content of 5 mol% or more is grown. When the shape is adjusted, the part composed of the original particles is called a low iodine layer, and the phase with a high normal content formed thereon is called a high iodine layer. For the degree phase,
The volume ratio of the low iodine layer is preferably 20% or more. The pAg during growth of the silver halide grains is preferably 9 or less.

At least one of the (111) planes of the octahedral or tetradecahedral crystals contained in the silver halide emulsion of the present invention
Silver halide grains having a raised portion at the center of one surface (hereinafter also referred to as "silver halide grains j of the present invention") are those obtained by any of the acid method, neutral method, and ammonia method. The particles may be grown continuously or may be grown stepwise while creating seed particles.The method of creating seed particles and the method of growing them may be the same or different. .

Although there is no limitation on the silver halide composition of the silver halide emulsion of the present invention, it is preferably substantially silver bromide or silver iodobromide. The emulsion of the present invention preferably contains iodine, but in this case, during grain growth, iodine ions may be added as an ionic solution such as a potassium iodide solution, and the iodine ions may be added as an ionic solution such as a potassium iodide solution, may also be added as particles with a small solubility product. It is more preferable to supply this iodine in the form of silver halide grains (described in detail below) having a small solubility product.

That is, the silver halide grains of the present invention are produced during the growth process of the grains (rAgX grains (1) for convenience in the following explanation of the grain growth process). In one embodiment, it is preferable that the grain growth of the silver halide grains is carried out in the presence of silver halide fine grains (referred to as "rAg be.

The solubility product being equal or lower means that the solubility product of the AgX particles (2) is the same as or smaller than the solubility product of the AgX particles (1). In addition, the solubility product in this specification is
In the ordinary chemical sense.

When adopting such an embodiment, Ag having a solubility product equal to or smaller than that of AgX particles (1)
The X particles (2) are present during at least one period of the growth process of the AgX particles (1), and the growth of the AgX particles (1) is performed in the presence of the AgX particles (2). Here, Ag
X particles (2) are particle growth elements () of AgX particles (1)
It can be used to grow the AgX particles (1) by making it exist until the supply of the chloride ion solution, silver ion solution, etc.) is finished.

The average particle size of the AgX particles (2) is smaller than the average particle size of the AgX particles (1), but may be larger depending on the case. Moreover, the AgX particles (2) generally have substantially no photosensitivity. This Ag
The average particle diameter of the X particles (2) is preferably 0.001 to 0.7 μm, more preferably 0.01 to 0.3 μm, and particularly preferably 0.1 to 0.01 μm.

It is preferable that the AgX particles (2) are allowed to exist in a suspension system (hereinafter referred to as mother liquor) that serves as a place for preparing the AgX particles (1) at the latest by the time the growth of the AgX particles (1) is completed.

When using silver halide seed grains, AgX grains (2
) may be present in the mother liquor before the seed particles,
It may be added to the mother liquor containing seed particles prior to the particle growth composition, it may be added during the addition of particle growth elements, or it may be added at two or more of the above-mentioned addition times. It may be added separately.

When grain growth is performed after silver halide nucleation without using seed grains, it is preferable to add AgX grains (2) after nucleation, either before or during the addition of grain growth elements. Often, it can be divided into two or more periods.

Furthermore, the AgX particles (2) and the particle growth element may be added all at once, continuously, or intermittently.

The AgX particles (2) and the particle growth element are preferably added to the mother liquor by a multi-jet method such as a double jet method under conditions where pH, pAg, temperature, etc. are controlled at a rate suitable for particle growth.

The AgX grains (2) and silver halide seed particles may be prepared in the mother liquor, or may be prepared outside the mother liquor and then added to the mother liquor.

As the water-soluble silver salt solution used for preparing the AgX particles (2), an ammoniacal silver salt solution is preferable.

The halogen composition of the AgX particles (2) is, for example, Ag
When the X grains (1) are silver iodobromide, silver iodobromide having a higher iodine content than silver iodide or growing silver iodobromide grains is preferable; for example, if the AgX grains (1) are When silver bromide is used, silver chlorobromide having a higher bromine content than silver bromide or growing silver chlorobromide is preferred. When the AgX grains (1) are silver iodobromide, it is particularly preferable that the AgX grains (2) are silver iodide.

When the AgX grains (1) are silver iodobromide or silver chloroiobromide, all the iodine used for grain growth is absorbed by the AgX grains (1).
Although it is preferable to supply it as 2), a part of it may be supplied as a halide aqueous solution to the extent that the effects of the present invention are not impaired.

Further, during the growth of silver halide grains, a known silver halide solvent such as ammonia, thioether, thiourea, etc. can be present.

Silver halide grains contain at least one selected from cadmium salts, zinc salts, lead salts, thallium salts, iridium salts, rhodium salts, iron salts, and complex salts thereof during the process of forming and/or growing the grains. By adding metal ions to the particles and/or on the surface of the particles, it is possible to contain these metal elements inside the particles and/or on the surface of the particles, and by placing them in an appropriate reducing atmosphere, reduction aggravation nuclei can be added inside the particles and/or on the particle surfaces. Can be granted.

In the silver halide emulsion of the present invention, unnecessary soluble salts may be removed after the growth of silver halide grains is completed, or they may remain contained. When removing the salts, please refer to the Research Discology +
Disclosure (hereinafter abbreviated as RD) 17643
It can be carried out based on the method described in item (■).

Further, the average grain size of the silver halide grains of the present invention is 0.0
5-30 micrometers are preferable, and 0.1-3.0 micrometers are more preferable.

The silver halide emulsion of the present invention can have any configuration, such as a polydisperse emulsion with a wide grain size distribution or a monodisperse emulsion with a narrow grain size distribution.

The silver halide emulsion of the present invention may be composed of a single emulsion or a mixture of several types of emulsions.

When carrying out the present invention, it is preferable to use a monodispersed emulsion. The silver halide emulsion of the present invention can be stably obtained as an emulsion with good monodispersity.

The monodisperse silver halide emulsion is preferably one in which the weight of silver halide contained within a grain size range of ±20% around the average grain size f is 60% or more of the weight of all silver halide grains. More preferably 70% or more, still more preferably 8
It is 0% or more.

Here, the average particle size Y, the frequency ni of particles having particle size ri
The particle size r when the product n1Xri3 of
Define i (3 significant digits, minimum digit is 4 to 5 digits).

That is, the grain size ri is, in the case of spherical silver halide grains,
In the case of particles having a shape other than spherical, the diameter is the diameter when the projected image is converted into a circular image with the same area.

The particle size can be obtained, for example, by photographing the particle with an electron microscope at a magnification of 10,000 to 50,000 times and measuring the particle diameter or projected area on the print (
The number of particles to be measured is assumed to be at least i,ooo indiscriminately).

Particularly preferred highly monodispersed emulsions are those with a distribution width of 20% or less, more preferably 15% or less, when the width of the distribution is defined as follows.

Here, the average particle diameter and standard deviation shall be determined from the above definition ri.

A method for obtaining a monodisperse emulsion is to add a water-soluble silver salt solution and a water-soluble halide solution to a gelatin solution containing seed particles.
There is a method of adding by double jet method under control of Ag and pH, and such means can be used.

In determining the addition rate, refer to JP-A-54-48521.
No. 5B-49938.

As a method for obtaining a more advanced monodispersed emulsion, JP-A-60-1
The growth method in the presence of tetrazaindene disclosed in No. 22935 can be applied.

Further, in the silver halide emulsion of the present invention, each grain preferably maintains identity in its shape.

Each particle maintains the same shape in its shape, which means that when the shape of the particle is observed using a scanning electron micrograph at a magnification of at least 10,000 times, at least the crystal habit and particle size are the same for each individual particle of interest. say something. In particular, in order to observe the fine structure of the surface, it is preferable to use a low acceleration voltage of 2 kV or less.

For example, if we take normal crystal grains as an example, the individual grains: (1) have the same hemostasis rate such as (111), (100), (331), etc., and (2) silver halide grains are core/shell grains. , the particle must have no part where no shell is formed during shell formation, ■ The flatness of the surface, such as surface irregularities, must be the same. ■ It must not contain twin grains, and the grain size is clearly 0. In this case, the individual particles are all the same in that they do not contain different fine or coarse particles or aggregated particles made up of two or more particles attached (these can be seen by microscopic observation). This is an example of maintaining the same shape.

Specifically, it is preferable that 70% or more of the number of grains in the emulsion are grains that maintain the same identity in the above shape, more preferably 80% or more, still more preferably 9.
It is preferable that 0% or more of the particles maintain the same identity in the above shape.

Further, it is preferable that the silver halide emulsion of the present invention maintains the same silver iodide content of each silver halide grain.

The silver iodide content of individual silver halide grains and the average silver iodide content in the emulsion of the present invention are determined by the EPMA method (Ele
ctron Probe Micro Analyze
r method).

This method is a technique in which a well-dispersed sample is prepared so that the emulsion grains do not come into contact with each other, and elemental analysis of extremely small portions is performed by X-ray analysis using electron beam excitation by irradiating the sample with an electron beam.

By this method, the halogen composition of each grain can be determined by determining the characteristic X-ray intensities of silver and iodine emitted from each grain.

If the silver iodide content of at least 50 grains is determined by the EPMA method, the average silver iodide content can be determined from the average thereof.

The equipment used for measurement does not require any special specifications, but
In the examples of the present invention described later, the silver iodide content of the emulsion was measured using an X-ray microanalyzer JXA-8621 manufactured by JEOL Ltd. The measurements were performed while cooling to a low temperature to eliminate electron beam damage.

The relative standard deviation of the silver iodide content of individual grains is the standard deviation of the silver iodide content when measuring the silver iodide content of at least 50 emulsion grains in the above measurement. This value is obtained by multiplying the value divided by the content rate by 100.

The emulsion of the present invention is preferably one in which the relative standard deviation of the silver iodide content of each individual silver iodobromide grain is 20% or less. In the emulsion of the present invention, it is preferable that the iodine content among the grains is even more uniform. That is, when the distribution of iodine content among particles was measured by the EPMA method, the relative standard deviation was 20.
% or less, more preferably 15% or less, particularly 10% or less.

The silver halide emulsion of the present invention can be chemically sensitized by conventional methods.

The silver halide emulsion of the present invention can be optically sensitized to a desired wavelength range using dyes known as sensitizing dyes in the photographic industry. Sensitizing dyes may be used alone, but
You may use two or more types in combination.

Antifoggants, stabilizers, etc. can be added to the silver halide emulsion. Gelatin is advantageously used as binder for the emulsion.

When a light-sensitive material is formed using the silver halide emulsion of the present invention, the emulsion layer and other hydrophilic colloid layers of the light-sensitive material can be hardened, and plasticizers, water-insoluble or poorly soluble synthetic polymers, etc. can contain a dispersion (latex) of

The silver halide emulsion of the present invention can be effectively used to form a light-sensitive material for color photography, and when used in the emulsion layer, it is generally used in the form of a color-forming coupler.

Furthermore, various fragments such as development accelerators, bleaching accelerators, developing agents, silver halide solvents, and toning agents can be produced by coupling with colored couplers, competing couplers, and oxidized products of developing agents, which have the effect of color correction. , hardener, fogging agent,
Compounds that release photographically useful fragments such as antifoggants, chemical sensitizers, spectral sensitizers, and desensitizers can be used.

When a photosensitive material is formed using the silver halide emulsion of the present invention, the photosensitive material can be provided with auxiliary layers such as a filter layer, an antihalation layer, and an antiirradiation layer. These layers and/or the emulsion layers may contain dyes that are leached or bleached from the light-sensitive material during the development process.

Photosensitive materials include formalin scavengers, optical brighteners,
A matting agent, a lubricant, an image stabilizer, a surfactant, a color anti-capri agent, a development accelerator, a development retardant and a bleach accelerator can be added.

As the support for the photosensitive material, any material can be used, such as paper laminated with polyethylene or the like, polyethylene terephthalate film, baryta paper, cellulose triacetate, and the like.

A dye image can be obtained using the light-sensitive material of the present invention by performing a commonly known color photographic process after exposure.

〔Example〕

Next, the present invention will be explained by examples. However, it goes without saying that the present invention is not limited to the following examples.

Example-1 (Preparation of silver iodide fine grain emulsion Al-1) An aqueous solution containing 5% by weight of ossein gelatin was added to a reaction vessel, and while stirring at 40°C, 3.5N silver nitrate aqueous solution and 3.5N iodine gelatin were added. 1 mol of each aqueous solution was added at a constant rate over a period of 30 minutes.

The PAg being added was controlled at 13.5 using conventional PAg control means.
I kept it.

The produced silver iodide is βAgI with an average grain size of 0.06 μm.
and T-Agl.

This emulsion will hereinafter be referred to as emulsion Al-1.

(Preparation of Emulsion EM-1) Emulsion EM-1 (corresponding to the emulsion of the present invention) was prepared using the following four types of solutions.

Aqueous solution (a-1) Compound (1) (average molecular weight -1300) Aqueous solution (a-2) Aqueous solution (a-3) Emulsion solution containing silver iodide fine grains (a-4) Temperature 60°
Aqueous solution of the above composition (a-1
), seed emulsion equivalent to 0.407 mol (average particle size 0.27
μm, average AgI content 2 mol%), pH and P
Ag was prepared using acetic acid and KBr aqueous solution.

Thereafter, while controlling the pH and PAg as shown in Table 1, the aqueous solutions (a-2), (a3) and (a-
4) were added by the triple jet method at the flow rates shown in Tables 29 and 3 and 4, respectively.

After the addition was completed, the mixture was washed with desalinated water in a conventional manner and dispersed in an aqueous solution containing gelatin.

According to electron microscopy, this emulsion has an average grain size of 0.46.
It was found that the emulsion was a highly monodisperse emulsion in which 92% of all silver halide grains were composed of octahedral grains having protrusions on the (111) plane, and the coefficient of variation in grain size distribution was 11.2%.

Table 5 shows the grain structure of the silver halide grains in this emulsion.

FIG. 1 is an electron microscope photograph of silver halide grains in this emulsion according to the present invention.

Table-1 Table-2 Addition pattern of (a-2) Table-3 Addition pattern of (a-3) Table-4 Addition pattern of (a-4) → means to keep pH and PAg constant, \ means continuous ↓ indicates a sudden decrease.

Table-5 Example-2 JP-A-61-246740, JP-A-61-27574
No. 1, by the method shown in JP-A No. 61-286845, the emulsion EM-1 had the same composition, grain size distribution, and average grain size as those of the emulsion EM-1 prepared in Example-1, and the final shape was Comparative emulsion EM-2, which is an octahedral grain having no protrusions on each (111) plane, was prepared.

Each of the prepared EM-1 and EM-2 emulsions was optimally sensitized with gold sulfur, and 3 sensitizing dyes (I) below were added per mol of AgX.
50 µm and 240 µm of sensitizing dye (II) were added to spectral sensitize to green sensitivity. Then TAI and 1-phenyl-5
- Stabilized by adding mercaptotetrazole. (Ag
X represents silver halide).

Furthermore, 5×10 −′ moles of the following magenta coupler (M −1) per mole of AgX, 6.2×1 O −′ moles of the following magenta coupler (M-2), and 4. OXl
0-3 mol of the following colored magenta coupler (CM-1
) is dissolved in di-t-nonyl phthalate and emulsified and dispersed in an aqueous solution containing gelatin, and a dispersion obtained is added to each emulsion, and then common photographic additives such as a spreading agent and a hardening agent are added. was added to prepare a coating solution, coated on the undercoated film base by a conventional method, dried, and prepared as sample Nα101.
．． 102 was created.

Ct Sensitizing dye ■M Wedge exposure was performed on each of the samples Nfl101 and 102 through a yellow filter according to a conventional method. Then,
The following processing steps (I) and (II) were performed using the following developing solution to determine the sensitivity.

Processing process (1) (35°C) Development 15 seconds fixation
Wash with water for 25 seconds
Dry for 25 seconds 1
5 seconds processing step (II) (35°C) Development 25 seconds fixation
Wash with water for 25 seconds
Dry for 25 seconds 1
The composition of the treatment liquid used in each 5 second treatment step is shown below.

Developer solution> Potassium sulfite 55.0 g Hydroquinone 25.0 g 1-
Phenyl-3-pyrazolidone 1.2g boric acid
10.0 g Sodium hydroxide 21.0 g Triethylene glycol 17.5 g 5-Methylbenzotriazole 0.07 g 5-Nitroindazole
0.14 g 1-phenyl-5-mercaptotetrazole O, OIS g Glutaraldehyde bisulfite 15.0 g Glacial acetic acid 16.0 g Potassium bromide 4.0 g Triethylenetetraminehexaacetic acid 2.5 g Add water to make 11. Adjust pH to 10.20.

Fixer> Ethylenediaminetetraacetic acid, di-sodium salt 5.0g Tartaric acid 3.0g Ammonium thiosulfate 130.9g Anhydrous sodium sulfite 7.3g Boric acid
7.0g acetic acid (90wt%)
5.5g Sodium acetate trihydrate
25.8g aluminum sulfate 18 hydrate
14.6 g sulfuric acid (50 gt%)
Add 6.77 g water and finish to lr, p
Adjust to H=4.20.

The results are shown in Table-6. Sensitivity is the minimum density (fog) +
Sample N is expressed as the reciprocal of the exposure amount giving 0.1.

It is expressed as a relative value when the sensitivity of the processing step (I) of 102 is set to 100.

[Brief explanation of the drawing]

FIG. 1 is an electron micrograph showing the grain structure of silver halide grains of emulsion EM-1, which is an emulsion of the present invention obtained in Examples 1 to 1.

Claims (1)

[Claims] Halogen containing silver halide grains in which the center of at least one {111} face of a 1-, octahedral, or 14-hedral crystal is raised, and the raised part occupies 50% or more of the area of the face. Silver emulsion.