JPH0690429B2 - Direct positive type silver halide photographic light-sensitive material - Google Patents

Description

The present invention relates to a direct positive silver halide photographic light-sensitive material, and more specifically to a direct positive photographic light-sensitive material having an internal latent image type silver halide emulsion layer. It is about.

[Conventional technology]

Conventionally known methods for obtaining a direct positive image are mainly classified into two types. One of the types is to use a silver halide emulsion having fog nuclei in advance and destroy fog nuclei or latent images in exposed areas by utilizing solarization or Herschel effect.
A positive image is obtained after development. The other type uses an internal latent image type silver halide emulsion which does not give fog (generally surface fog) until the image exposure, and after the image exposure, the fog treatment (nucleation treatment) is performed, and then the surface development is performed. A positive image can be obtained by carrying out the surface image while performing the fogging treatment after the image exposure.

The above-mentioned fogging treatment may be performed by exposing the entire surface, may be chemically performed by using a fogging agent, may be performed by using a strong developing solution, and may be further performed by heat treatment or the like. The internal latent image type silver halide milk photographic emulsion is
Having a photosensitive nucleus mainly inside the silver halide crystal grain,
A silver halide photographic emulsion in which a latent image is formed inside a grain upon exposure.

Of the two methods for forming a positive image, the latter type method generally has higher sensitivity than the former type method and is suitable for applications requiring high sensitivity.

Various techniques have been known so far in this technical field. For example, U.S. Patents 2,592,250 and 2,466,957
No., No. 2,497,875, No. 2,588,982, No. 3,761,266,
No. 3,761,276, No. 3,796,577 and British Patent 1,151,36
The method described in No. 3 etc. is known.

Regarding the mechanism of forming a positive image, for example, Photographic Science and Engineering (Phot
ographic Science and Engineering) Volume 20, p. 158 (197
As described in 6), it is considered as follows. Photoelectrons generated in the silver halide crystal grains by the imagewise exposure are selectively captured inside the grains to form an internal latent image. Since this internal latent image acts as an effective trap center for electrons in the conduction band, in the exposed particles, the electrons injected in the subsequent fog development process are trapped inside and assist the latent image. become. In this case, the latent image is not developed because it is entirely inside. On the other hand, in the particles that have not been subjected to image exposure, at least some of the injected electrons are captured on the surface of the particles, and the particles are developed by surface development.

[Problems to be solved by the invention]

Although a photographic light-sensitive material that forms a positive image can be produced by using a conventionally known technique, further improvement in photographic performance is desired in order to apply these photographic light-sensitive materials to various photographic fields. There is.

Higher sensitivity is obtained by chemically sensitizing the inside of silver halide grains as disclosed in US Pat. Nos. 3,761,267 and 3,206,313, or by using core / shell type emulsions doped with polyvalent metal ions. However, this type of emulsion has the disadvantage of low image density. U.S. Pat.No. 3,761,276 discloses that the surface of silver halide grains is subjected to a certain degree of chemical ripening treatment in order to improve the above-mentioned drawback of low image density. This is disadvantageous because the silver emulsion has extremely poor stability for long-term storage and poor production stability.

On the other hand, it is disclosed in JP-A-47-32820. With a silver halide emulsion consisting mainly of silver chloride, the maximum density of the positive image obtained is relatively high, but the minimum density is not sufficiently low, and a blurred image results.

Therefore, in order to put into practical use the direct positive light-sensitive material using the above-mentioned internal latent image type emulsion, the internal latent image type silver halide having a sufficiently high maximum density and a sufficiently low minimum density and excellent storage stability. The appearance of emulsions is desired.

In the present invention, the maximum density is sufficiently large and the minimum density is sufficiently small by using a unique internal latent image type silver halide emulsion. Moreover, it is an object of the present invention to provide a highly sensitive silver halide photographic light-sensitive material excellent in storage stability.

[Means for solving problems]

The direct positive silver halide photographic light-sensitive material according to the present invention has at least one silver halide emulsion layer containing internal latent image type silver halide grains whose surface is not fogged in advance until image exposure, In a photographic light-sensitive material in which a positive image can be directly obtained by surface development after image exposure, after fog treatment and / or while performing fog treatment, the internal latent image type silver halide grains form a core and a core. At least one shell containing at least one layer of a compound containing silver chloride in at least the surface layer composition of the shell, and forming at least the surface layer of the shell by at least one compound represented by the following general formula [I] It is characterized by being performed below.

General formula [I] In the formula, X represents H or NH ₂ . Y is OH, NH ₂ or (R ¹ and R ² each represent H, an alkyl, cycloalkyl or aryl group, provided that R ¹ and R ² do not become H at the same time).

Hereinafter, the present invention will be described in detail.

In the present invention, silver halide having any halogen composition can be used as long as at least the shell surface layer containing silver chloride substantially contains silver chloride. Examples thereof include silver chloride, silver chlorobromide, silver chloroiodobromide, and silver chloroiodide.

The shell layer of the silver halide grain of the present invention can completely coat the surface of the silver halide grain or selectively coat a part of the surface. In the present invention, the shell surface layer containing silver chloride preferably accounts for 10% or more of the grain surface.

The shell in the silver halide grain of the present invention may be a single monolayer in the silver halide composition or a coated shell composed of more than two layers.

The coating shell is composed of at least the outermost layer and a layer adjacent thereto, but may have a structure in which layers having different silver halide compositions are laminated.

Further, the multilayer shell layer is in the radial direction of the silver halide grains,
It may have a structure in which the silver halide composition changes continuously.

The layered shell according to the present invention may have any silver halide composition as long as the outermost layer of the multilayer shell or the surface layer of the shell contains silver chloride. Examples thereof include silver iodobromide, silver bromide, silver chlorobromide, silver chloroiodide, and silver chlorobromoiodide.

The shell according to the present invention preferably covers 50% or more of the surface area of the core, and particularly preferably completely covers the core.

The core of the silver halide grain of the present invention preferably consists mainly of silver bromide, and may further contain silver chloride and / or silver iodobromide. The silver halide grains forming the core may have any shape, for example, cubic crystal, regular octahedron, dodecahedron or a mixture thereof, spherical, tabular or amorphous. Particles may be used. The average grain size and grain size distribution of the silver halide grains constituting the core of the present invention can be widely varied depending on the desired photographic performance, but the grain size distribution is preferably narrow. That is, it is preferable that the silver halide grains constituting the core of the present invention are substantially monodisperse.

The term "monodisperse silver halide grains having a core" as used herein means that the weight of silver halide grains contained in a grain size range of ± 20% around the average grain size of the silver halide grains constituting the core is totally halogenated. The silver content is 60% or more, preferably 70% or more, and particularly preferably 80% or more.

The average particle diameter herein the product n _i × r _i ³ of the frequency n _i and r _i ³ of particles having a particle size r _i means the particle r _i having the maximum (three significant figures, the least significant Numbers are rounded to four).

In the case of spherical silver halide grains, the particle size as used herein means the diameter thereof, or in the case of grains having a shape other than spherical,
It is the diameter when the projected image is converted into a circular image of the same area.

The particle size can be obtained, for example, by enlarging the particles by an electron microscope from 10,000 times to 50,000 times and projecting them, and measuring the particle diameter or the area at the time of projection on the print (the number of measured particles is not measured). It is assumed that there are more than 1000 discriminations.)

In this specification, the term “average particle size” is used in the meaning defined above.

The method for producing the monodisperse core emulsion is described in, for example, JP-B-48.
The double jet method disclosed in JP-A-36890, JP-A-54-48520, JP-A-54-65521 and the like can be used. In addition, the premix method described in JP-A-54-158220 may be used.

The core of the silver halide grain in the present invention may be chemically sensitized, doped with metal ions, both of them, or both of them may not be applied at all. Good.

Many methods are known for chemical sensitization. That is,
The sensitization method is a sulfur image sensation, gold layer sensitization, reduction sensitization, noble metal sensitization and a combination of these sensitization methods. As the sulfur image-sensitizing agent, thiosulfates, thioureas, thiazoles, rhodanins and other compounds can be used. Such a method is, for example, U.S. Pat.Nos. 1,574,944 and 1,623,499,
No. 2,410,689, No. 3,656,955, etc.

The core of the silver halide grain used in the present invention is, for example, U.S. Patent Nos. 2,399,083, 2,597,856 and 2,642,361.
As described in the above publication, it can be sensitized with a water-soluble gold compound, or can be sensitized with a reduction sensitizer. For such a method, for example, U.S. Pat.
Reference can be made to 7,850, 2,518,698, and 2,983,610.

Furthermore, noble metal sensitization can be carried out by using a noble metal compound such as platinum, iridium or palladium. For such a method, for example, U.S. Pat.
Reference can be made to the description of US Patent No. 060 and US Pat. No. 618,061.

The core of the silver halide grain in the present invention can be doped with metal ions. To dope the core with metal ions, it can be added as a water-soluble salt of the metal ions, for example, in any process of forming the core particles. As a preferred specific example of the metal ion, iridium,
There are metal ions such as lead, antimony, bismuth, gold, osmium, and rhodium. These metal ions are preferably used in a concentration of 1 × 10 ⁻⁸ to 1 × 10 ⁻⁴ mol per mol of silver.

The core of the silver halide grain in the present invention may be one which has not been subjected to the above-mentioned chemical sensitization treatment or metal ion doping. In this case, it is considered that in the process of coating the core particle with the shell, a photosensitive center is generated at the interface between the core and the shell due to crystal strain or the like, and in this regard, see U.S. Pat.Nos. 3,935,014 and 3,957,488. can do.

A double jet method or a premix method can be used as the method of forming the shell on the core. Alternatively, fine grain silver halide may be mixed with the core emulsion and Ostwald ripening may be performed.

The surface layer of the shell of the silver halide grain in the present invention is formed in the presence of at least one compound represented by the general formula [I]. Specific examples of the representative compounds are as follows.

As a method for synthesizing these compounds in the present invention, a known method or a method analogous thereto can be easily synthesized.

For example, it is synthesized by the method described in J. Am. Chem. Soc. 81, 3963 to 3967 (1959) and 79, 2251 to 2252 (1957). In addition, some of the compounds are commercially available as chemical reagents.

Among the compounds represented by the general formula [I], 6-substituted aminopurines are preferable because they are excellent in the positive image improving effect which is the object of the present invention.

In the present invention, at least the outermost layer of the shell layer may be present in advance during the formation of the surface layer, or may be added at the stage of shell formation.

The addition amount of these compounds in the present invention is in the range of 10 ^-6 to 10 ^-1 mol, and preferably 10 ^-5 to 10 ^-2 mol, per 1 mol of silver halide produced.

Some of these compounds in the present invention are known as minor components contained in gelatin, but the content is much smaller than the amount sufficient for the effects of the present invention to be exhibited. Therefore, the effect is completely out of the question.

It is preferable that the surface of the silver halide grain of the present invention is not chemically sensitized, or even if it is sensitized, it is in a slight degree.

When chemically sensitizing the surface of the silver halide grain of the present invention,
It can be carried out by the same method as the chemical sensitization of the core particles.

The silver halide grains in the present invention preferably have a narrow grain distribution even after shell formation and are substantially monodisperse. That is, it is preferable that the entire silver halide grain is substantially monodisperse as defined above.

The monodispersity is preferably 70% or more, particularly preferably
80% or more.

The ratio of the silver halide of the core and the shell of the present invention can be arbitrarily determined, but the ratio of the shell is preferably 10% to 99% based on the total silver halide of the silver halide grains.

The composition ratio of the silver halide grains of the present invention is preferably 5% to 80% in terms of silver chloride as a whole.

The meaning that the grain surface is not prefogged means that the emulsion used in the present invention is 35 mgAg / d on a transparent film support.
The density obtained when the test piece coated so as to have a surface area of m ² was developed with the surface developing solution A described below at 20 ° C. for 10 minutes without being exposed to light, was obtained.
6 It means preferably not exceeding 0.4.

Surface developer A 2.5 m 1-Ascorbic acid 10 g NaBO ₂ .4H ₂ O 35 g KBr 1 g Water was added 1 The silver halide emulsion according to the present invention was prepared by exposing a test piece prepared as described above to light. Internal developer B with the following formulation
It gives a sufficient density when developed by.

Internal developer B Meter 2g Sodium sulfite (anhydrous) 90g Hydroquinone 8g Sodium carbonate (monohydrate) 52.5g KBr 5g KI 0.5g Add water 1 If more specifically stated, about 1 part of the test piece When exposed to a light intensity scale for a predetermined time up to 2 seconds and developed with internal developer B at 20 ° C. for 10 minutes, another part of the test piece exposed under the same conditions is treated with a surface developer. At A
It exhibits a maximum density of at least 5 times, preferably at least 10 times that obtained when developed at 20 ° C. for 10 minutes.

The silver halide emulsion according to the present invention can be optically sensitized with a commonly used sensitizing dye. A combination of sensitizing dyes used for supersensitization such as an internal latent image type silver halide emulsion and a negative type silver halide emulsion is also useful for the silver halide emulsion of the present invention. Research Disclosure No.151 for sensitizing dyes
No. 62 and No. 17643 can be referred to.

The photographic light-sensitive material of the present invention is image-exposed (photographed) by an ordinary method
After that, a positive image can be easily obtained directly by developing the surface. That is, the main step of directly producing a positive image is to form a fog nucleus by a chemical action or an optical action after image exposure of a photographic light-sensitive material having a prefogged internal latent image type silver halide emulsion layer of the present invention. And / or after the fogging treatment is performed.
Alternatively, the surface development is performed while performing the fogging treatment. Here, the fogging treatment can be carried out by using a compound that gives the entire surface exposure or generates a fogging nucleus, that is, a fogging agent.

In the present invention, the overall exposure is performed by immersing or moistening the imagewise exposed exposure material in a developing solution or other aqueous solution, and then uniformly exposing the entire surface.
The light source used here may be any light within the exposure wavelength range of the photographic light-sensitive material, and it is possible to apply high-illuminance light such as flash light for a short time, or to apply weak light for a long time. Good. Further, the time of the whole surface exposure can be varied over a wide range so that the best positive image can be finally obtained depending on the photographic light-sensitive material, the development processing conditions, the kind of the light source used and the like.

A wide variety of compounds can be used as the fog agent used in the present invention. The fog agent only needs to be present at the time of development processing. For example, in the constituent layers other than the support of the photographic light-sensitive material (especially halogen). It is preferably contained in a silver halide emulsion layer) or in a developing solution or a processing solution prior to the development processing. The amount used can be varied over a wide range according to the purpose. The preferable addition amount is 1-1,500 mg, preferably 10-1,000 mg per mol of silver halide when added to the silver halide emulsion layer. Is. When it is added to a processing solution such as a developing solution, the addition amount is preferably 0.01 to 5 g / l, particularly preferably 0.05 to 1 g / l.

Examples of the fogging agent used in the present invention include US patents.
Hydrazines described in 2,563,785 and 2,588,982, or hydrazide or hydrazone compounds described in US Pat. No. 3,227,552; US Pat. No. 3,615,615
No. 3,718,479, No. 3,719,494, No. 3,734,738 and No. 3,759,901, and multiple ring quaternary nitrogen salt compounds; and silver halides such as acylhydrazinophenylthioureas described in US Pat. No. 4,030,925. Examples thereof include compounds having an adsorption group on the surface. Further, these fogging agents can be used in combination. For example, Research Disclosure No. 15162 describes that a non-adsorption type fogging agent is used in combination with an adsorption type fogging agent, and this combination technique is also effective in the present invention. The fogging agent used in the present invention is an adsorption type,
Any of the non-adsorption type can be used, or they can be used in combination.

Specific examples of useful fogging agents include hydrazine hydrochloride,
Phenylhydrazine hydrochloride, 4-methylphenylhydrazine hydrochloride, 1-formyl-2- (4-methylphenyl) hydrazine, 1-acetyl-2-phenylhydrazine, 1-acetyl-2- (4-acetamidophenyl)
Hydrazine, 1-methylsulfonyl-2-phenylhydrazine, 1-benzoyl-2-phenylhydrazine,
Hydrazine compounds such as 1-methylsulfonyl-2- (3-phenylsulfonamidophenyl) hydrazine and formaldehydephenylhydrazine; 3- (2-formylethyl) -2-methylbenzothiazolium bromide, 3- (2-formyl) Ethyl) -2-propylbenzothiazolium bromide, 3- (2-acetylethyl)
-2-Benzylbenzoselenazolium bromide, 3-
(2-Acetylethyl) -2-benzyl-5-phenyl-benzoxazolium bromide, 2-methyl-3-
[3- (phenylhydrazino) propyl] benzolium bromide, 2-methyl-3- [3- (p-tolylhydrazino) propyl] benzothiazolium bromide, 2
-Methyl-3 [3- (p-sulfophenylhydrazino) propyl] benzothiazolium bromide, 2-methyl-3- [3- (p-sulfophenylhydrazino)
Pentyl] benzothiazolium iodode, 1,2-dihydro-3-methyl-4-phenylpyrido [2,1-b] benzothiazolium bromide, 1,2-dihydro-3-methyl-4-phenylpyrido [ 2,1-b] -5-phenylbenzothiazolium bromide, 4,4'-ethylenebis (1,2-dihydro-3-methylpyrido [2,1-b] benzothiazolium bromide), 1,2 -N-substituted quaternary cycloammonium salts such as dihydro-3-methyl-4-phenylpyrido [2,1-b] benzoselenazolium bromide; 5- [1-ethylnaphtho (1,2-b) thiazoline-2
-Ylideneethylidene] -1- (2-phenylcarbazoyl) methyl-3- (4-sulfamoylphenyl)-
2-thiohydantoin, 5- (3-ethyl-2-benzothiazolinidene) -3- [4- (2-formylhydrazino) phenyl] rhodan, 1- [4- (2-formylhydrazino) ) Phenyl] 3-phenylthiourea, 1,3
-Bis [4- (2-formylhydrazino) phenyl]
Thiourea etc. are mentioned.

The photographic light-sensitive material having a silver halide emulsion layer according to the present invention is directly exposed to light after imagewise exposure or surface development treatment in the presence of a fogging agent to directly form a positive image. This surface development processing method means processing with a developing solution which does not substantially contain a silver halide solvent.

Examples of the developer that can be used in the surface developer used for developing the photographic light-sensitive material according to the present invention include ordinary silver halide developers such as polyhydroxybenzenes such as hydroquinone, aminophenols and 3-pyrazolidones. , Ascorbic acid and its derivatives, reductones, phenylenediamines and the like or 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-o
-Toluidine, 4-amino-3-methyl-N-ethyl-
N- (β-methanesulfonamidoethyl) aniline,
4-amino-3-methyl-N-ethyl-N- (β-hydroxyethyl) aniline and the like can be mentioned. These developers may be contained in the emulsion in advance so that they act on the silver halide during the immersion in the high pH aqueous solution.

The developer used in the present invention may further contain a specific antifoggant and development inhibitor, or these developer additives may be optionally incorporated in the constituent layers of the photographic light-sensitive material. Is.

To the silver halide emulsion according to the present invention, various photographic additives such as a wetting agent, a film physical property improving agent and a coating aid can be added depending on the purpose. Examples of the wetting agent include dihydroxyalkane and the like, and further examples of the film physical property improving agent include, for example, a copolymer of alkyl acrylate or alkyl methacrylate with acrylic acid or methacrylic acid, a styrene-maleic acid copolymer, styrene maleic anhydride. A water-dispersible fine particle polymer substance obtained by emulsion polymerization such as an acid haf alkyl ester copolymer is suitable, and examples of the coating aid include saponin and polyethylene glycol lauryl ether. Other photographic additives include gelatin plasticizers, surfactants, UV absorbers, pH adjusters, antioxidants, antistatic agents, thickeners, graininess improvers, dyes, moldants, whitening agents, and developing agents. It is also possible to use speed regulators, matting agents and the like.

The silver halide emulsion prepared as described above is coated on a support through an undercoat layer, an antihalation layer, a filter layer, etc., if necessary, to give the internal latent image type silver halide photographic material of the present invention. obtain.

It is useful to apply the photographic light-sensitive material according to the present invention to color, and in this case, it is preferable to include cyan, magenta and yellow dye image-forming couplers in the silver halide emulsion. As the coupler, those usually used can be used.

Further, it is useful to use an ultraviolet absorber, for example, thiazolidone, benzotriazole, acrylonitrile, or a benzophenone compound in order to prevent fading due to actinic rays having a short wavelength in the dye image, particularly, tinupin PS, 320,
It is advantageous to use 326, 327, and 328 (all manufactured by Ciba Geigy) alone or in combination.

Examples of the support of the photographic light-sensitive material according to the present invention include polyethylene terephthalate film, a polycarbonate film, a polystyrene film, a polypropylene film, a cellulose acetate film, glass, baryta paper, polyethylene laminated paper, etc. which are undercoated if necessary. To be

In the silver halide emulsion layer according to the present invention, as a protective colloid or a binder, other than gelatin, an appropriate gelatin derivative can be used according to the purpose. Examples of suitable gelatin derivatives include acylated gelatin, guanidized gelatin, carbamylated gelatin, cyanoethanolated gelatin, esterified gelatin and the like.

Further, in the present invention, other hydrophilic binders (binders) may be included depending on the purpose, and hydrolyzed to 19 to 20% containing colloidal albumin, agar, gum arabic, dextran, alginic acid and acetyl. Cellulose derivatives such as cellulose acetate, polyacrylamide, imidized polyacrylamide, casein, vinyl alcohol, vinylcarboxylic polymers such as urethane carboxylic acid groups such as vinylaminoacetate copolymer or cyanoacetyl group, polyvinyl alcohol, polyvinylpyrrolidone, hydrolyzed Degraded polyvinyl acetate, polymer obtained by polymerization of protein or saturated acylated protein and monomer having vinyl group, polyvinyl pyridine, polyvinyl amine, polyaminoethyl methacrylate, polyethylene It may be added to the photographic light-sensitive material constituting layers such as the emulsion layer or the intermediate layer, the protective layer, the filter layer and the backing layer according to the purpose, and the hydrophilic binder may be added depending on the purpose. Appropriate plasticizers, lubricants, etc. may be contained.

The constituent layers of the photographic light-sensitive material according to the present invention can be hardened with any suitable hardener. These hardeners include chromium salts, zirconium compounds, aldehyde compounds such as formaldehyde and mucohalogen acid, halotriazine compounds, polyepoxy compounds, ethyleneimine compounds,
Examples thereof include vinyl sulfone type and acryloyl type hardeners.

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

When the photographic light-sensitive material of the present invention is used for full color, at least one red-sensitive silver halide emulsion layer, green-sensitive silver halide emulsion layer and blue-sensitive silver halide emulsion layer are coated on a support. To be done. At this time, at least one light-sensitive silver halide emulsion layer may contain the internal latent image-type silver halide grains according to the present invention, but all the light-sensitive silver halide emulsion layers include the internal latent image-type silver halide grains according to the present invention. It preferably contains latent image type silver halide grains. Further, each light-sensitive silver halide emulsion layer may be the same color-sensitive layer or may be separated into two or more layers having different sensitivities. In this case, at least one layer having different sensitivities should be the same. The color-sensitive layer may contain the internal latent image type silver halide grains according to the present invention, but it is preferable that all the emulsion layers contain the internal latent image type silver halide grains according to the present invention.

The photographic light-sensitive material according to the present invention is used for general black and white, X ray,
For color, false color, printing, infrared, micro,
It can be effectively applied to various uses such as silver dye bleaching, and also colloid transfer method, silver salt diffusion transfer method, Rogers U.S. Patents 3,087,817, 3,185,567 and 2,983,60.
No. 6, U.S. Pat.No. 3,253,915 by Weyerts et al., U.S. Pat. And the color image transfer method and the color diffusion transfer method described in JP-A-3,415,646.

〔Example〕

Next, the present invention will be specifically described with reference to examples. The aspect of the present invention is not limited to the illustrated embodiment.

Example 1 An equimolar aqueous solution of silver nitrate and an aqueous solution of potassium bromide were added at about 50 ° C.
A cubic brominated emulsion A having an average particle size of 0.5 μm was obtained by simultaneously adding the particles by a controlled double jet method for 50 minutes.

Emulsion A was used as a core particle, and an aqueous silver nitrate solution and an aqueous sodium chloride solution were added at the same time to obtain a cubic core / shell type emulsion B having an average particle size of 0.6 μm. The obtained emulsion had a narrow grain size distribution and was a monodisperse emulsion.

Similarly, using emulsion A as a core grain, core / shell type emulsions C, D, E, F and G were obtained. However, before forming the shell, the compounds of the present invention as shown in Table 1 were added to the core emulsion (the addition amount was based on the core emulsion). After the usual extender and hardener were added, the coating was applied on the cellulose triacetate support so that the coated silver amount was 35 mg / 100 cm ^2, and dried to obtain a sample.

These samples were subjected to the following treatments. That is, each sample was stored at a temperature of 20 ° C. and a relative humidity of 55% for 3 days (condition-1) and at a temperature of 50 ° C. and a relative humidity of 80% for 3 days (condition-2). The obtained sample is exposed through an optical wedge for sensitometry using a sensitometer (hereinafter referred to as wedge exposure),
Development was carried out for 4 minutes at 20 ° C. with a developer having the following formulation, and then fixing, washing with water and drying were carried out by a conventional method.

Phenidone 0.4g Sodium sulfite (anhydrous) 75g Hydroquinone 10g Sodium carbonate (monohydrate) 40g Potassium bromide 4g 5-Methylbenzotriazole 10mg 1-Acetyl-2-phenylhydrazine (fogging agent) 0.1g Add water 1 (water The pH was adjusted to 12.5 with sodium oxide.) The results of measuring the maximum density and the minimum density of the obtained positive image are shown in Table 1.

As is clear from the results in Table 1, the emulsion of the present invention has a large maximum density and a small minimum density, and the storage stability under high temperature and high humidity is remarkably improved.

Example 2 An equimolar aqueous solution of silver nitrate and an aqueous solution of potassium bromide were added at about 50 ° C.
A tetradecahedral silver bromide emulsion having an average grain size of 0.4 μm was obtained by simultaneous addition for 40 minutes by the controlled double jet method. However, 0.02 mg of potassium hexachloroiridate per mol of silver was added 5 minutes after the addition of the aqueous silver nitrate solution and the aqueous potassium bromide solution was started. To the emulsion thus obtained, 2.0 mg of sodium thiosulfate was added per mol of silver, and the mixture was chemically ripened at 60 ° C. for 60 minutes to obtain emulsion H.
Got

Using the emulsion H as core particles, core / shell type emulsions IL as shown below were obtained.

Emulsion I: Emulsion H was used as a core particle, and an aqueous solution of silver nitrate and an aqueous solution of potassium bromide were simultaneously added to obtain an average particle size of 0.5 μm.
Thus, a tetradecahedral core / shell type emulsion of m was obtained.

Emulsion J: Using Emulsion H as a core particle, an aqueous silver nitrate solution and an aqueous potassium bromide solution were simultaneously added to grow to a particle size of 0.5 μm, and then an aqueous silver nitrate solution and an aqueous sodium chloride solution were added simultaneously to obtain an average particle size of 0.55 μm. A cubic core / shell type emulsion was obtained.

Emulsion K: A core / shell emulsion K was obtained in the same manner as the emulsion J. That is, Emulsion J was prepared in the same manner except that the compound 11 of the present invention was added in an amount of 150 mg per mol of silver prior to the addition of the aqueous silver nitrate solution and the aqueous sodium chloride solution.

Emulsion L: A core / shell emulsion L was obtained in the same manner as the emulsion K described above. That is, it was prepared in exactly the same manner as Emulsion K except that an aqueous solution containing potassium bromide and sodium chloride (molar ratio KBr: NaCl = 1: 1) was added in place of the aqueous sodium chloride solution.

Sensitizing dye 5,5 'was added to each of Emulsions I to L obtained above.
-Diphenyl-9-ethyl-3,3'-disulfopropyloxacarbocyanine sodium salt and 1- (2,4,6-trichlorophenyl) -3- as a magenta coupler
(2-Chloro-5-octadecylsuccinimidoanilino) -5-pyrazolone was dissolved in a solvent, and the resulting dispersion was emulsified and dispersed in a gelatin aqueous solution. Further, a hardening agent was added to the resin-coated paper support. The coated silver was coated so that the coated silver amount was 4 mg / 100 cm ^2, and dried.

These samples were wedge-exposed through a yellow filter and developed with a developer having the following formulation at 38 ° C. for 3 minutes.

4-Amino-3-methyl-N-ethyl-N- (β-methanesulfonamidoethyl) aniline sulfate 5g Sodium sulfite (anhydrous) 2g Sodium carbonate (monohydrate) 15g Potassium bromide 1g Benzyl alcohol 10ml Water was added. 1 (adjusted to pH 10.2 with potassium hydroxide.) However, the entire surface was uniformly exposed to white light of 1 lux for 20 seconds from the start of development for 20 seconds. Then, washing, bleach-fixing, washing with water and drying were carried out by a conventional method.

Table 2 shows the results of measuring magenta positive images of the obtained samples.

As is clear from the results in Table 2, the maximum concentration is improved by precipitating silver chloride in the outermost layer of the shell of the core / shell particles (Comparison-2), but the shell is further formed in the presence of the compound of the present invention. It can be seen that the emulsion of the present invention has a small minimum density and exhibits good positive characteristics.

Example 3 An equimolar amount of an aqueous solution of ammoniacal silver nitrate and an aqueous solution of potassium bromide were added simultaneously by the double jet method for about 20 minutes while maintaining constant pH (9.0) and pAg (8.3) at 40 ° C. A cubic silver bromide emulsion M having a grain size of 0.6 μm was obtained.

Further, the following core / shell type emulsions N and O were prepared.

Emulsion N: Using Emulsion M as a core particle, an ammoniacal silver nitrate aqueous solution and a mixed aqueous solution of potassium bromide and sodium chloride (molar ratio: KBr: NaCl = 1: 1) are maintained at a constant pH (8.0) for about 10 minutes. Average particle size of 0.7
A μm cubic core / shell emulsion was obtained.

Emulsion O: A core / shell type emulsion O was obtained in the same manner as the emulsion N. That is, ammoniacal silver nitrate aqueous solution and potassium bromide /
One minute after the addition of the sodium chloride mixed aqueous solution was started, an emulsion N was prepared in the same manner as in the emulsion N except that 300 mg of the compound 13 of the present invention was added per mol of silver.

Sensitizing Dye 5, to each of Emulsions N and O obtained above,
5'-dichloro-3,3'-di (3-sulfobutyl) -9-
Ethyl thiacarbocyanine sodium salt and cyan coupler 2,4-dichloro-3-methyl-6- [α- (2,4-di-tert-acylphenoxy) butyramide] phenol are added, and a hardener is further added. It was coated on a resin-coated paper support so that the coated silver amount was 5 mg / 100 cm ² .

These samples were stored under the same conditions (condition-1 and condition-2) as in Example 1 described above, and further exposed and developed in exactly the same manner as in Example 2. Table 3 shows the results of the cyan-positive images obtained.

As is clear from the results shown in Table 3, it can be seen that the emulsion of the present invention gives a good positive image and has improved storage stability.

[Effect of the invention] By using the internal latent image type silver halide emulsion peculiar to the present invention, a high-sensitivity silver halide photograph having a sufficiently large maximum density and a sufficiently small minimum density and excellent storage stability. A photosensitive material can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-56955 (JP, A) JP-A-47-32820 (JP, A) JP-A-58-215644 (JP, A) JP-A-57- 23932 (JP, A) JP-B 4-28288 (JP, B2) JP-B 4-41813 (JP, B2) JP-B 4-64057 (JP, B2) JP-B 4-30571 (JP, B2)

Claims (1)

[Claims] 1. A photographic light-sensitive material having a silver halide emulsion layer containing at least one internal latent image type silver halide grain to obtain a direct positive image, wherein the internal latent image type silver halide grain is used. Is composed of a core and at least one shell that coats the core, contains at least surface layer silver chloride in the shell, and has at least the surface layer formed by the following general formula [I]. A positive-positive silver halide photographic light-sensitive material, which is carried out in the presence of at least one of the compounds described above. General formula [I] [In the formula, X represents H or NH ₂ . Y is OH, NH ₂ or (R ¹ and R ² each represent H, an alkyl group, a cycloalkyl group, or an aryl group, provided that R ¹ and R ² do not become H at the same time). ]