JPH01159636A - Direct positive silver halide photographic sensitive material - Google Patents

Abstract

PURPOSE:To obtain a stable positive image which has a less change in the characteristics of the title material even at the time of preserving with age in a high temp. and humidity by incorporating an inner latent image type silver halide particle having a core/shell type and <=0.45mum of an average particle size in the sensitive material, and by aging an inner latent image type silver halide particle in the presence of a fine particle composed of silver halide. CONSTITUTION:The inner latent image type silver halide particle having the core/shell type and <=0.45mum of the average particle size is incorporated in at least one layer of the silver halide emulsion layer, and the inner latent image type silver halide particle is aged in the presence of the fine particle composed of the silver halide. Thus, even in case of using the particle having a small particle size, the change of the photographic characteristics is lessened even at the time of preservating with age in the high temp. and humidity, and the good positive image having the sufficiently high max. optical density and the sufficiently low min. optical density is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a direct positive silver halide photographic light-sensitive material. In particular, the present invention relates to a direct positive silver halide photographic light-sensitive material that can provide stable positive images with little fluctuation in photographic performance even when stored over time at high temperatures and high humidity.

[Conventional technology and its problems]

There are two main types of conventionally known techniques for obtaining direct positive images. One type uses an emulsion containing silver halide grains that have fogged nuclei in advance;
A positive image is obtained after development by destroying fogging nuclei or latent images in exposed areas using solarization, the Burschel effect, or the like. Another type uses an emulsion containing internal latent image type silver halide grains that do not cause fog (generally surface fog) until image exposure, and performs fogging treatment (nucleation treatment) after image exposure. A positive image can then be obtained by performing surface development, or by performing surface development while performing fogging treatment after image exposure.

The above-mentioned fogging treatment may be carried out by exposing the entire surface to light, or may be carried out chemically using a fogging agent, or may be carried out using a strong developer (and may also be carried out by heat treatment, etc.). An emulsion containing internal latent image type silver halide grains is an emulsion containing silver halide grains that has photosensitive nuclei mainly inside the silver halide crystal grains and forms a latent image inside the grains upon exposure. means.

Of the two techniques for forming a positive image, the latter type is more sensitive than the former type - for boat fishing, and is suitable for applications requiring high sensitivity.

Various techniques are known in this technical field. For example, U.S. Patent Nos. 2.592.250, 2.466.957, 2.497.875,
, 588°982, 3,761,266, 3,
The methods described in No. 761,276, No. 3796.577, British Patent No. 1,151,363, etc. are known.

The formation mechanism of positive images is not necessarily clear, but for example,
science and engineering) 2
Volume 0, page 58 (1976) states the following:

Photoelectrons generated within the silver halide crystal grains by imagewise exposure are selectively captured inside the grains, forming an internal latent image. This internal latent image acts as an effective capture center for electrons in the conductive band, so in exposed particles, electrons injected during the subsequent fogging and development process are captured internally and strengthen the latent image. become. In this case, the latent image is all internal and is not developed. On the other hand, in particles that have not undergone image exposure, at least some of the injected electrons are captured on the particle surface, and the particles are developed by surface development.

Although it is possible to produce photographic materials that form positive images by using the above-mentioned known techniques, further improvement in photographic performance is desired in order to actually apply these photographic materials to various photographic fields. ing.

For example, in such a direct positive silver halide photographic light-sensitive material, relatively high sensitivity and image density (maximum density D□
8. ), it has the disadvantage of high fogging (minimum density,...) in the background of the image.

The degree of fogging depends on the type of silver halide emulsion,
Although it varies depending on manufacturing conditions, post-manufacturing storage conditions, development conditions, etc., the quality of the white background of the image is significantly impaired, especially when stored over time at high temperature and high humidity.

Furthermore, in recent years in the photographic industry, development and subsequent post-processing steps (desilvering, fixing, washing, etc.) are carried out at high temperatures to shorten and speed up the processing time. By the way, when the above-mentioned fog development is carried out at a high temperature, for example, 30° C. or higher, the fog that occurs during storage over time is further amplified, which is a problem in putting this type of emulsion into practical use.

Conventionally, it has been known to use various antifoggants or development inhibitors for the purpose of improving such undesirable phenomena. For example, U.S. Patent No. 2,497,917
Benzotriazoles listed in
Heterocyclic thione compounds described in US Pat. No. 5-12709, tetrazole compounds described in US Pat. No. 3,352,672, and the like have been used as inhibitors. However, even when these compounds are used, they are insufficient to suppress fog that occurs over time, the minimum density cannot be made sufficiently low, and a sufficient white background cannot be obtained. Also, the use of large amounts of inhibitors as suggested in these patents is not preferred since it significantly inhibits development and lowers image density.

Furthermore, in the field of direct positive silver halide photographic light-sensitive materials, it is well known that so-called core/shell type grains consisting of a core and a shell covering the core are used as internal latent image type silver halide grains. . This type of particle is characterized by a combination of the internal properties of the core (eg, photosensitivity) and the surface properties of the shell (eg, developability). For example, the emulsion containing core/shell type silver halide grains disclosed in U.S. Pat. It has not yet become smaller.

Furthermore, JP-A No. 59-208540 states that compared to silver halide grains with a relatively large grain size, small grains with an average grain size of 0.4 μm or less have a lower maximum density or a higher minimum density. It is disclosed that good positive images are not obtained and that this is improved by relatively high levels of fog inside the particles.

As a result of further study on this matter, the inventors found that
It was found that sufficient performance improvement could not be achieved simply by adjusting the internal fog. In other words, as the particle size becomes smaller (for example, the average particle diameter is 0.45 μm or less), performance fluctuations during long-term storage are relatively large. It has become clear that increasing the internal fog further deteriorates storage stability and causes large fluctuations in photographic performance.

This problem occurs when particles with small sizes are used to adjust the gradation, for example, when high-sensitivity particles and low-sensitivity particles are mixed, the average particle size of the low-sensitivity particles is 0.4.
This becomes a big problem when particles of 5 μm or less are used.

[Purpose of the invention]

The present invention has been made to solve the above problems,
Even when using particles with a small particle size, there is little change in photographic performance even when stored over time under high temperature and high humidity conditions, and good positive images with a sufficiently high maximum density and a sufficiently low minimum density can be obtained. The purpose of the present invention is to provide a positive silver halide photographic material.

[Structure and operation of the invention]

The above object of the present invention is to provide a direct positive silver halide photographic light-sensitive material having at least IN a silver halide emulsion layer containing internal latent image type silver halide grains, at least one of the silver halide emulsion layers comprising: Average particle size is 0.45
A photosensitive material containing core/shell type internal latent image type silver halide grains of micrometer or less, and the internal latent image type silver halide grains are aged in the presence of fine grains made of silver halide. , achieved.

The present invention will be explained in detail below.

The direct positive silver halide photographic light-sensitive material of the present invention has at least one silver halide emulsion layer containing internal latent image type silver halide grains.

The emulsion forming the silver halide emulsion layer containing the internal latent image type silver halide grains according to the present invention mainly forms a latent image inside the silver halide grains, and directs most of the photosensitive nuclei inside the grains. It is an emulsion having silver halide grains having the following properties, and contains any silver halide such as silver bromide, silver chloride, silver chlorobromide, silver iodobromide, silver chloroiodobromide, and the like.

Particularly preferably, the emulsion is substantially free of silver halide solvent by exposing a portion of a sample coated with the emulsion to a transparent support to a light intensity scale for a defined period of time up to about 1 second. When developing for 4 minutes at 20°C using the following surface developer A, which develops only the surface image of the particles,
Another portion of the same emulsion sample is exposed in the same way and the maximum density is not greater than 175, which is the maximum density obtained when developed for 4 minutes at 20°C in internal developer B, described below, which develops the image inside the grains. It shows. More preferably, the maximum density obtained with surface developer A is not greater than 1/10 of the maximum density obtained with internal developer B.

Surface developer A Metol 2.5 g L-ascorbic acid 10 g Sodium metaborate (
(tetrahydrate salt) 35g Potassium bromide Add 1g water
1 β internal developer B Metol 2.0 g Sodium sulfite (anhydrous) 90.0 g Hydroquinone 8.0 g Sodium carbonate (monohydrate) 52.5 g Potassium bromide
5.0g potassium iodide 0
．． Add 5 g of water. II1 The internal latent image type silver halide grains according to the present invention have an average grain size of 0.45 μm or less.

Conventionally, direct positive silver halide photographic materials using such small grains with an average grain size of 0.45 μm or less have tended to exhibit large fluctuations in performance due to storage over time as described above. By adopting the structure of the present invention, it has become possible to obtain a photosensitive material with little variation in performance even when using such small particle diameters.

In the present invention, the average particle size is the principal size in the case of cubic particles;
In the case of spherical particles, it is expressed by its diameter, and in the case of particles of other shapes, it is expressed by the average diameter when its projected image is converted into a circular image of the same area.

The average particle size can be obtained, for example, by magnifying the particles 10,000 to 50,000 times with an electron microscope and projecting them, and measuring the particle diameter or area at the time of projection on the print (
It is assumed that the number of particles to be measured is indiscriminately 1000 or more. )
.

In this specification, the term average particle size shall be used in the meaning defined above.

The internal latent image type silver halide grains according to the present invention are aged in the presence of fine grains made of silver halide grains. Here, "fine particles" refer to particles that exist as particles during ripening and have a particle size small enough to dissolve and recrystallize at or before the end of ripening. The preferred average particle size of such fine particles cannot be determined unconditionally because it varies depending on the silver halide composition, etc.
Preferably it is usually 0.1 am or less. The smaller the average particle diameter, the better from the viewpoint of dissolution before the completion of ripening.

The silver halide composition of the fine grains is arbitrary; for example, any one of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide, silver chloroiodide, etc. is used alone. or can be used in combination as appropriate. From the viewpoint of solubility, it is preferable to use silver halide containing silver chloride, and silver chloride is particularly preferable. The silver iodide content is preferably 5 mol% or less.

The amount of silver halide fine grains to be used is 2 when the internal latent image type silver halide grains according to the present invention are 100 (mol%).
It is preferable to use it in an amount of 0 (mol %) or less, more preferably 10 (mol %) or less.

In order to ripen the internal latent image type silver halide grains according to the present invention in the presence of fine grains made of silver halide, the internal latent image type silver halide grains are formed in advance in the liquid in which the internal latent image type silver halide grains are present. The above-mentioned fine particles may be added and aged,
Alternatively, the fine grains may be formed in a liquid in which the internal latent image type silver halide grains are present (for example, by adding a halide and a silver salt to the liquid to form fine grains).

Here, ripening means that after the formation of internal latent image type silver halide grains,
This refers to leaving particles under certain conditions (for example, certain temperature conditions) for a certain period of time to form particles with desired properties.

The internal latent image type silver halide grains according to the present invention have a core/shell type grain structure. Regarding this particle structure below,
I will explain further.

The core of the internal latent image type silver halide grains according to the present invention preferably mainly consists of silver bromide, and further contains silver chloride and/or
Alternatively, it may contain silver iodobromide. The silver halide grains forming the core may have any shape; for example, they may be cubic, hexahedral, octahedral, dodecahedral, or a mixture thereof; they may also be spherical, tabular, irregular, etc. It may be a regular shaped particle. Although the average particle size and particle size distribution of the silver halide grains constituting the core can be varied widely depending on the desired photographic performance, a narrower particle size distribution is more preferable. That is, the silver halide grains constituting the core are preferably substantially monodisperse.

The method for producing the above-mentioned monodisperse core emulsion is, for example,
B-36890, JP-A-54-48520, JP-A-54
The double jet method disclosed in Japanese Patent Application No.-65521 and the like can be used. In addition, a premix method described in JP-A-54-158220 and the like may also be used.

The core of the internal latent image type silver halide grains according to the present invention is chemically sensitized, doped with metal ions, or both, or not at all. It may be something.

Many methods are known for chemical sensitization.

That is, sensitization methods include sulfur sensitization, gold sensitization, reduction sensitization, noble metal sensitization, and combinations of these sensitization methods. As the sulfur aggravating agent, thiosulfates, thioureas, thiazoles, rhodanines, and other compounds can be used. Such methods are described, for example, in U.S. Pat. No. 1,574,944.
No. L623,499, No. 2.410,689,
It is described in No. 3,656,955, etc.

The core of the internal latent image type silver halide grains according to the present invention is disclosed in, for example, U.S. Pat.
As described in No. 56, No. 2,642.361, etc., sensitization can be carried out with a water-soluble gold compound or with a reduction sensitizer. Such methods are described, for example, in U.S. Pat.
, No. 518,698, No. 2.983,610, etc. can be referred to.

Furthermore, noble metal sensitization can also be carried out using noble metal compounds such as platinum, iridium, palladium, and the like. Such methods are described, for example, in U.S. Pat.
8,060 and British Patent No. 618.061.

The core of the internal latent image type silver halide grains according to the present invention can be doped with metal ions. To dope the core with metal ions, the metal ions can be added as water-soluble salts, for example, during any process of forming the core particle. Preferred specific examples of metal ions include metal ions such as iridium, lead, antimony, bismuth, gold, osmium, and rhodium. These metal ions are preferably used in a concentration of 1.times.10@-8 to 1.times.10@1 mole per mole of silver.

The core of the internal latent image type silver halide grains according to the present invention may not be subjected to the above-mentioned chemical sensitization treatment or metal ion doping. In this case, in the process of covering the core grain with a shell, It is thought that a photosensitive center is generated at the interface between the shell and the shell due to crystal strain and other factors.
Regarding this, U.S. Patent No. 3.935.014, 3.
Reference may be made to the description in No. 957.488.

The silver halide shell that covers the core can be prepared by the double jet method, in which an aqueous silver salt solution and an aqueous halogen salt solution are simultaneously added and mixed, or the multiple jet method, in which an aqueous silver salt solution and two or more aqueous halogen solutions are independently added and mixed. This can be done by

The double jet method uses 1'Ag or p of the mixed liquid.
A so-called Chondral double jet method in which mixing is performed while controlling H can be used.

The PAg value during shell preparation varies depending on the composition of silver halide, but for shells containing silver chloride, it is 8.
．． It is 5 or less, preferably 8.0 or less. The pH value can be appropriately controlled according to a method such as an acid method, a neutral method, or an ammonia method.

Although the ratio of the core to the shell of the core/shell type internal latent image type silver halide grains according to the present invention prepared as described above is arbitrary, it is preferable that the core is completely covered with the shell. . The silver halide compositions of the core and shell may be the same or different, but as mentioned above, the core preferably consists mainly of silver bromide, and the outermost layer or surface layer of the shell contains silver chloride. Therefore, it is preferable that the compositions are different from each other. Further, the internal latent image type silver halide grains according to the present invention preferably have a clear layered structure.

Regarding whether or not it has a clear laminated structure,
This can be determined by measuring X-ray diffraction. That is, when a diffraction curve is created by plotting diffraction intensity versus diffraction angle, the diffraction curve is distinguished by the appearance of at least two peaks depending on the different silver halide compositions of the core and shell. Regarding the measurement method of X-ray diffraction, please refer to “X-ray spectroscopy for analytical chemistry” (Rigaku Denki Publishing) and “Purethane of
The Society of Scientific Photography of Japan, Vol. 13, page 5, etc., is a silver halide coated with Cu- oriented on a substrate using alpha rays. It can be measured by powder method X-ray diffraction of an emulsion of grains.

Silver halide emulsions containing internal latent image type silver halide grains according to the present invention can be optically sensitized using commonly used sensitizing dyes. The combination of sensitizing dyes used for supersensitization of internal latent image type silver halide emulsions, negative silver halide emulsions, etc. is a silver halide emulsion containing internal latent image type silver halide grains according to the present invention. It is also useful for Regarding sensitizing dyes, see Research Disclosure (hereinafter referred to as Research Disclosure).
Reference may be made to Nα15162 and Nα17643 (abbreviated as RD).

In order to obtain a direct positive image using the direct positive silver halide photographic light-sensitive material of the present invention, image exposure (so-called shadowing, in which light is irradiated onto the light-sensitive material to form an image) is carried out in a conventional manner. ), a positive image can be easily obtained directly by surface development. Here, surface development means developing latent image nuclei formed on the surface of silver halide grains, which is usually processed with a developer substantially free of silver halide solvent. The main process for forming a direct positive image is generally to process the internal latent image type photosensitive material after image exposure and/or after subjecting it to a process that generates fog nuclei by chemical action or chemical action, that is, a fog process. , consisting of carrying out surface development while performing a fogging process.

The fogging process can be performed by exposing the entire surface to light or using a compound that generates fogging nuclei, that is, a fogging agent.

For example, full-surface exposure is performed by immersing or moistening the image-exposed photosensitive material in a developer or other aqueous solution, and then uniformly exposing the entire surface. The light source used here may be any light within the wavelength range to which the photographic light-sensitive material is sensitive, and it may be possible to apply high-intensity light such as a flash light for a short period of time, or to apply low-intensity light for a long period of time. . Also, the total exposure time depends on the photographic material,
Depending on the development processing conditions, the type of light source used, etc., it can be varied over a wide range to ultimately obtain the best positive image.

In addition, when fogging is used, a wide variety of compounds can be used as fogging agents, and this fogging agent only needs to be present at the time of development. It may be contained in a photosensitive material containing silver particles, a developer, or a processing solution prior to development, but it is preferably contained in the photosensitive material (particularly preferably in the silver halide emulsion layer). Furthermore, the amount used can vary widely depending on the purpose.

As the fogging agent, both adsorption type and non-adsorption type can be used, and they can also be used in combination.

Specific examples of useful fogging agents include phenylhydrazine hydrochloride, 1-formyl-2-(4-methylphenyl)hydrazine, 1-acetyl-2-phenylhydrazine,
- Hydrazine compounds such as methylsulfonyl-2-(3-phenylsulfamidophenyl)hydrazine; 3-(2
N-substituted quaternary cycloammonium salts such as -formylethyl)-2-methylbenzothiazolium bromide, 2-methyl-3-[3-(phenylhydrazino)probylcobenzothiazolium bromide; 5 -[1-ethylnaphtho(1,2-b)thiazolin-2-ylideneethylidene]
-t-L(2-phenylcarbazoyl)methyl-3-(
4-sulfamoylphenyl)-2-thiohydantoin, 5-(3-ethyl-2-penzothiazolinylidene)-
3-[4-(2-formylhydrazino)phenyl]rhodanine, 1-[4-(2-formylhydrazino)phenyl]-3-phenylthiourea, 1.3-bis[4-(
Examples include 2-formylhydrazino)phenylcothiourea.

The direct positive silver halide photographic light-sensitive material of the present invention can be processed with a surface developer to obtain an image as described above, but the developer that can be used in the surface developer for such development is usually silver halide developer,
Examples include polyhydroxybenzenes such as hydroquinone, aminophenols, 3-pyrazolidones, ascorbic acid and its derivatives, reductones, phenylenediamines, and mixtures thereof. Specifically, hydroquinone, aminophenol, N-methylaminophenol, 1-phenyl-3-pyrazolidone, 1-phenyl-4,4-dimethyl-3-pyrazolidone, 1-phenyl-4-methyl-4-hydroxymethyl- 3-pyrazolidone, ascorbic acid, N,N-diethyl-P-phenylenediamine, diethylamino-0-toluidine, 4-
Examples include amino-3-methyl-N-ethyl-N-(β-methanesulfonamidoethyl)aniline, 4-amino-3-methyl-N-ethyl-N-(β-hydroxyethyl)aniline, and the like. These developers can also be included in the emulsion in advance and allowed to act on the silver halide during immersion in a high pH aqueous solution.

The developer that can be used in the practice of the present invention may further contain specific antifoggants and development inhibitors, or these developer additives may be optionally incorporated into the constituent layers of the photographic material. It is possible.

Depending on the purpose, various photographic additives such as wetting agents, film property improvers, and coating aids may be added to the silver halide emulsion containing the internal latent image type silver halide grains according to the present invention.

Other photographic additives include gelatin plasticizers, surfactants, ultraviolet absorbers, PH adjusters, antioxidants, antistatic agents, thickeners, graininess improvers, dyes, mordants, brighteners, and developers. Speed modifiers, matting agents, etc. may also be used.

The silver halide emulsion prepared as described above is coated on a support via a subbing layer, an antihalation layer, a film layer, etc., if necessary, to form an internal latent image type silver halide photographic light-sensitive material of the present invention. Obtainable.

It is useful to apply the photographic material of the present invention to color applications, and in this case it is preferred to include cyan, magenta and yellow dye image-forming couplers in the silver halide emulsion. As the coupler, commonly used couplers can be used, and a specific example is RD-17643 (1978
(December 1979) and No. 18717 (November 1979).

Furthermore, it is useful to use an ultraviolet absorber to prevent the dye image from fading due to short-wavelength actinic rays.

Examples of the support for the photographic material of the present invention include polyethylene terephthalate film, polycarbonate film, polystyrene film, polypropylene film, cellulose acetate film, glass, baryta paper, polyethylene laminate paper, etc., which have been undercoated as necessary. .

The silver halide emulsion layer containing internal latent image type silver halide grains according to the present invention contains a storage colloid or a binder (
In addition to gelatin, suitable gelatin derivatives can be used as the binder depending on the purpose. Suitable gelatin derivatives include, for example, acylated gelatin, guanidylated gelatin, carbamylated gelatin, cyanoethanolated gelatin, and esterified gelatin. In addition, other hydrophilic binders may be included depending on the purpose, and polyvinyl alcohol, polyvinylpyrrolidone, hydrolyzed polyvinyl acetate, etc. are used.

Further, the constituent layers of the photographic material of the present invention can be hardened with any suitable hardening agent.

These hardeners include chromium salts, zirconiums,
Examples include aldehyde hardeners such as formaldehyde and mucohalogen acids, halotriazine hardeners, polyepoxy compounds, ethyleneimine hardeners, vinyl sulfone hardeners, and acryloyl hardeners.

Further, the photographic light-sensitive material of the present invention has a silver halide emulsion layer (photosensitive layer) containing at least one layer of an emulsion containing internal latent image type silver halide grains according to the present invention on a support, and a filter. layer, intermediate layer, protective layer, subbing layer, backing layer,
It is possible to provide a number of different photographic constituent layers, such as antihalation layers.

The photographic material of the present invention can be effectively applied to various uses such as black and white general use, X-ray use, color use, false color use, printing use, infrared use, micro use, silver dye bleaching use, etc.
Also, colloid transfer method, silver salt diffusion transfer method, U.S. Pat. No. 3,087,817 to Rogers, U.S. Pat. U.S. Pat. No. 3,227.550 to Whitemore et al., U.S. Pat. No. 3.22 to Barr et al.
No. 7.551, Whitemore et al., U.S. Pat. No. 3,227.552, and Rand et al., U.S. Pat. It can also be applied to color image transfer methods, color diffusion transfer methods, etc.

〔Example〕

The present invention will be specifically described below with reference to Examples. However, the embodiments of the present invention are not limited thereto.

Example-1 By adding and mixing equimolar silver nitrate aqueous solution and potassium bromide aqueous solution at 60°C by double jet method while maintaining PAg at 7, the average particle size after desalting was 0.20μ.
A cubic silver bromide grain emulsion (A) of m was obtained. Next, using this emulsion (A) as a core particle, a silver nitrate aqueous solution and a sodium chloride aqueous solution were added at 50°C and pA by a double jet method.
Add at the same time while maintaining g6, average particle size 0.25μ
A cubic core/shell type emulsion ('B) of m was obtained.

Under the same mixing conditions as emulsion (A), the average grain size was 0.35 μm.
A cubic silver bromide emulsion (C) was obtained. Next, this emulsion (
C) was used as a core particle and further grown while simultaneously adding a silver nitrate aqueous solution and a sodium chloride aqueous solution at 50°C and pAg6 to obtain a cubic core/shell type emulsion (D) having an average grain size of 0.45 μm.

A cubic silver bromide emulsion (E) having an average grain size of 0.6 μm was obtained under the same mixing conditions as for emulsion (A). Furthermore, this emulsion (E)
Simultaneously add silver nitrate aqueous solution and sodium chloride aqueous solution (5
A cubic core/shell type emulsion (F) having an average grain size of 0.75 μm was obtained at 0°C and pAg6)L.

As a result of X-ray diffraction measurements of the above emulsions (B), (D), and (F), two distinct peaks corresponding to the core and shell, respectively, appeared in the diffraction curves (not shown). It was confirmed that the emulsion grains had a layered structure.

Next, each of emulsions (B) and (D) was divided into equal parts, one part (sample Nα1, 3) was used as a blank, and the other part (sample Nα2, 4) was treated with fine grain chloride as shown in Table-1. Silver (corresponding to fine particles made of silver halide) was added and ripened at 50'C for 30 minutes. However, the fine grain silver chloride is a silver chloride emulsion with an average grain size of 0.05 μm prepared by simultaneously adding and mixing a 1.2 mol aqueous solution of sodium chloride and a 1 mol aqueous solution of silver nitrate into an aqueous gelatin solution.

Sensitizing dye 5,5'-diphenyl-9-ethyl-3,3'- was added to each of the obtained emulsions (B), (D) and (F).
Disulfopropyloxacarbocyanine sodium salt and 1-(2,4,6-)lichlorophenyl)-3-(2-chloro-5-octadecylsuccinimidoanilino)-5-pyrazolone as magenta coupler are dissolved in a solvent. Then, a dispersion of this emulsified dispersion in an aqueous gelatin solution was added, a hardening agent was added, and the coating was coated on a resin-coated paper support so that the coated silver amount was 5 cm/100 cffl, dried, and the sample was prepared. Nα1-5 were produced.

These samples Nos. 091 to 5 were subjected to the following treatments. That is, each sample was stored for 6 days at a temperature of 25°C and 55% relative temperature (condition-1), and for 6 days at a temperature of 45°C and 80% relative temperature (condition-2). The processed sample was wedge-exposed through a yellow filter and exposed at 38° using a developer with the following formulation.
Development was performed for C3 minutes.

4-amino-3-methyl-N-ethyl-N-(β-methanesulfonamidoethyl) aniline sulfate
5g sodium sulfite (anhydrous)
2g Sodium carbonate (-hydrate) 15g Potassium bromide 1g Benzyl alcohol 10d Add water
1i (pH 1 with potassium hydroxide)
Adjusted to 0.2. ) However, 10 seconds after the start of development.
The entire surface was uniformly exposed to white light at 1 lux for 1 sec.

Next, the film was bleach-fixed, washed with water, and dried in a conventional manner.

Maximum density of magenta positive image (D, ,
The results of measuring the minimum concentration (D-i-,) are shown in the table below.
1 * mole/mole of silver in emulsion As is clear from the results in Table 1, sample size 2. By adding fine particles made of silver chloride to I' and aging it, the maximum concentration is high and the minimum concentration is low and stable even if stored over time under high temperature and high humidity as in condition-2,
It can be seen that a good positive image can be obtained.

In contrast, comparative samples N11l and 11i outside the present invention
[L3 has a significantly higher minimum concentration when stored over time under high temperature and high humidity as in condition-2, compared to comparative sample No. 5, which uses particles with a large particle size. A good positive image cannot be obtained like the sample.

〔Effect of the invention〕

As mentioned above, the direct positive silver halide photographic light-sensitive material of the present invention exhibits a good positive image with little fluctuation in photographic performance even when stored over time at high temperature and high humidity, has a sufficiently high maximum density, and a sufficiently low minimum density. This has the effect that an image can be obtained.

Patent applicant: Konica Corporation

Claims (1)

[Scope of Claims] 1. In a direct positive silver halide photographic light-sensitive material having at least one silver halide emulsion layer containing internal latent image type silver halide grains, at least one of the silver halide emulsion layers is , contains core/shell type internal latent image type silver halide grains with an average grain size of 0.45 μm or less, and the internal latent image type silver halide grains are aged in the presence of fine grains made of silver halide. A direct positive silver halide photographic light-sensitive material.