JPH0468617B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a heat-developable photosensitive material, and more particularly to a heat-developable photosensitive material with high sensitivity and low thermal fog. [Background of the Invention] Compared to the conventional wet method, the method of performing the development process to obtain an image by dry heat treatment requires less processing time,
It has many advantages in terms of cost and pollution concerns. Regarding heat-developable photosensitive materials in which the above-mentioned development process can be carried out by dry heat treatment, there are descriptions, for example, in Japanese Patent Publication Nos. 43-4921 and 43-4924, and black-and-white types consisting of organic silver salts, silver halide, and reducing agents. A heat-developable photosensitive material is disclosed. Attempts have been made to improve such heat-developable photosensitive materials and obtain color images by various methods. For example, JP-A-57-179840, JP-A No. 57-186744
No. 57-198458, No. 57-207250, No. 58-
40551, 58-58543, 58-79247, and
No. 59-12431, No. 59-22049, No. 59-68730,
No. 59-124339, No. 59-124333, No. 59-124331
No. 59-159159, No. 59-181345, 59-
No. 159161, No. 58-116537, No. 58-123533, No. 159161, No. 58-116537, No. 58-123533, No.
There are Nos. 58-149046 and 58-14947. The basic structure of a color type heat-developable photosensitive material for obtaining color images consists of a photosensitive element and an image-receiving element, and the photosensitive element basically consists of photosensitive silver halide, photosensitive silver halide,
It consists of an organic silver salt, a reducing agent (hereinafter also referred to as a developer), a dye-donating substance, and a binder. In the present invention, only the photosensitive element is referred to as a heat-developable photosensitive material in a narrow sense. In the former black-and-white type, optical information is given to the photosensitive silver halide through image exposure, and during thermal development, the photosensitive silver halide and the reducing agent are present in the vicinity of the exposed layer in the photosensitive layer. The catalytic action of the photosensitive silver halide causes an oxidation-reduction reaction to produce silver, and the exposed areas of the photosensitive layer are blackened to form a silver image. In addition, in the color type, optical information is given to the photosensitive silver halide through image exposure, and the developer that has or has not acted on the photosensitive silver halide during thermal development reacts with the dye-providing substance. By doing so, the dye that forms the image is released or formed. The image-forming dye obtained by thermal development is transferred to an image-receiving element to form an image. In recent years, attempts have been made to use light sources with low exposure illuminance, such as LEDs, CRTs, FOTs, and semiconductor lasers, as exposure means for heat-developable photosensitive materials. On the other hand, the reduction of the time required to obtain an image is also being considered, and in particular for photosensitive materials suitable for rapid processing such as heat-developable photosensitive materials, studies are being carried out from various viewpoints. Studies are underway to improve the sensitivity of heat-developable photosensitive materials. High sensitivity of this heat-developable photosensitive material can be achieved by increasing the silver iodide content in the photosensitive silver halide, but on the other hand, thermal fogging can be improved by increasing the silver iodide content. The problem of an increase in To deal with this, it is possible to use thermal fog inhibitors that reduce thermal fog, such as the mercury compound of U.S. Patent No. 3,589,903, the N-halogen compound of West German Patent No. 2,402,161,
Peroxides in U.S. Patent No. 2500508, sulfur compounds in U.S. Patent No. 2617907, palladium compounds in U.S. Patent No. 4102312, sulfinic acids in U.S. Pat.
Mercaptotriazole, U.S. Patent No. 4137079
No. 1,2,4-triazole and the like can be mentioned. However, these thermal antifoggants are either extremely harmful to the human body or have only a small antifogging effect, and the reality is that no satisfactory thermal antifoggant has yet been found. As a result of intensive studies, the present inventors found that silver halide grains containing core/shell type photosensitive silver halide grains containing silver iodide in a specific range and having a lower silver iodide content in the surface layer than in the inner layer. The inventors have discovered that by using an emulsion, a heat-developable photosensitive material with high sensitivity and low thermal fog can be obtained, leading to the present invention. [Object of the Invention] Therefore, an object of the present invention is to provide a heat-developable photosensitive material that has high sensitivity and low thermal fog. [Structure of the Invention] The above object of the present invention is that the photosensitive silver halide emulsion of a heat-developable photosensitive material is a photosensitive silver halide grain containing silver iodide, and the silver iodide content in the inner layer of the grain is 4 mol% to 7 mol%, a core/shell type photosensitive silver halide grain having a silver iodide content in the surface layer of the grain of 0 mol% to 6 mol% and lower than the silver iodide content in the inner layer. This is achieved by developing photosensitive materials. [Specific Structure of the Invention] The photosensitive silver halide grains used in the present invention have a core/silver iodide content in the surface layer (synonymous with shell) that is lower than the inner layer (synonymous with core). These are shell-type photosensitive silver halide grains. When the silver iodide content in the surface layer of the core/shell type photosensitive silver halide is higher than or equal to that of the inner layer, disadvantages such as large thermal fog appear. Other silver halide components of the photosensitive silver halide containing silver iodide in the core of the core/shell type photosensitive silver halide grains in which the surface layer of the grain used in the present invention has a lower silver iodide content than the inner layer. Although there are no particular restrictions on the silver halide component, preferred silver halide components include silver iodobromide and silver chloroiodobromide. The core of the photosensitive silver halide grains containing silver iodide used in the present invention is prepared by P. Glafkides, published by P. Glafkides, published by Paul Monte.
Chimieet Physique Photographique, Paul
Montel) (1967), written by G.F. Duffin,
Photographic Emulsion Chemistry (published by The Focal Press) (GFDuffin,
Photographic Emulsion Chemistry，The
Focal Press) (1966), Bui El Zerikman et al., Making and Coating.
Photographic Emulsion (The Focal Press) (VLZelikman etal, Making
and Coating Photographic Emulsion，The
Focal Press) (1964). That is, any of the acid method, neutral method, ammonia method, etc. may be used, but the ammonia method is particularly suitable. Further, as a method for reacting the soluble silver salt and the soluble halogen salt, any one of a one-sided mixing method, a simultaneous mixing method, a combination thereof, etc. may be used. It is also possible to use a back mixing method in which silver halide grains are formed in an excess of silver ions. One of the simultaneous mixing methods is to arbitrarily control the pAg of the solution in the reaction vessel in which silver halide is produced.
A controlled double-jet method that controls the addition rate of silver and halogen solutions can also be used. According to this method, a so-called monodisperse silver halide emulsion in which the crystal shape and grain size of individual silver halide grains are nearly uniform can be used. is obtained. In the present invention, the above-mentioned monodisperse silver halide emulsion is defined as one having a particle size distribution in which the variation in the size of silver halide grains contained in the emulsion is less than a certain percentage of the average grain size as shown below. means. The grain size distribution of a photosensitive silver halide emulsion (hereinafter referred to as a monodisperse emulsion) consisting of a group of photosensitive silver halide grains with uniform grain morphology and small variation in grain size exhibits an almost normal distribution;
When the standard deviation is easily determined and the width of the distribution is defined by the relational expression: standard deviation/average grain size x 100 = width of distribution (%), the The preferable distribution width is 15% or less, and more preferably the monodispersity with a distribution width of 10% or less. The core/shell type photosensitive silver halide grain emulsion used in the present invention can be produced by using monodisperse photosensitive silver halide grains as a core and coating the core with a shell. To make the core a monodisperse silver halide grain,
Particles of desired size can be obtained by the double jet method while keeping pAg constant. Also,
Silver halide emulsions containing highly monodisperse photosensitive silver halide can be prepared by the method described in JP-A-54-48521. A preferred embodiment of the method is a method in which a potassium iodobromide-gelatin aqueous solution and an ammoniacal silver nitrate aqueous solution are added to a gelatin aqueous solution containing silver halide seed particles while changing the addition rate as a function of time. It is manufactured by. At this time, a silver halide emulsion containing highly monodisperse core silver halide grains can be obtained by appropriately selecting the time function of addition rate, PH, pAg, temperature, etc. Monodisperse core/shell type photosensitive silver halide grains used in the present invention are produced by sequentially growing shells using monodisperse core grains as described above according to the method for manufacturing monodisperse emulsions. A silver halide emulsion containing silver halide can be obtained. In the core/shell type photosensitive silver halide grains used in the present invention, the thickness of the shell covering the core is 0.05% to 90% of the silver halide grain size.
is preferable, and more preferably in the range of 1% to 80%. The core/shell type photosensitive silver halide grains used in the present invention preferably have a silver iodide content of 4 mol% to 7 mol% in the silver halide composition of the core, and a silver halide content of 4 mol% to 7 mol% in the silver halide composition of the shell. , the silver iodide content is 0 mol% to 6 mol%. If the silver iodide content of the core is less than 4 mol%, there will be little thermal fog, but disadvantages such as low photographic sensitivity will appear, and if the silver iodide content exceeds 7 mol%, Disadvantages such as increased fogging appear. Further, in the core/shell type photosensitive silver halide grains used in the present invention, it is sufficient that the silver iodide content in the surface layer (shell) of the grain is lower than that in the inner layer (core), but preferably the silver iodide content in the surface layer is lower than that in the inner layer (core). This is a case where the silver iodide content is 2 mol% or more lower than the silver iodide content of the inner layer. There is no particular restriction on the average particle size of the photosensitive silver halide grains used in the present invention, but it is preferably 0.01 μm to 5.0 μm, and more preferably,
It is 0.05 μm to 2.0 μm. In the present invention, the average particle size of photosensitive silver halide grains means, in the case of spherical silver halide grains,
In the case of particles with shapes other than cubic or spherical, the diameter is the average value of the diameter when the projected image is converted into a circular image of the same area, and the individual particle size is ri, and the number When is ni, then is defined by the following formula. =Σniri/Σni The above particle size can be measured by various methods commonly used in the technical field for the above purpose. A typical method is Loveround's "particle size analysis method" AS.
TM Symposium on Light Microscopy, 1955, pp. 94-122 or "Theory of the Photographic Process" by Mies and James, No. 3
Edition, published by Macmillan (1966), Chapter 2. The particle size can be measured using the projected area or approximate diameter of the particle. If the particles are of substantially uniform shape, the particle size distribution can fairly accurately describe the diameter as a projected area. The photosensitive silver halide emulsion containing photosensitive silver halide grains used in the present invention may be chemically sensitized by any method in the field of photographic technology.
Such sensitization methods include various methods such as gold sensitization, sulfur sensitization, gold-sulfur sensitization, and reduction sensitization. In the present invention, as another method for preparing photosensitive silver halide, it is also possible to allow a photosensitive silver salt-forming component to coexist with an organic silver salt described below to form photosensitive silver halide in a part of the organic silver salt. . The photosensitive silver salt-forming component used in this preparation method is an inorganic halide, for example, a halide represented by MXn (where M represents an H atom, NH ₄ group or a metal atom, and X represents Cl, Br). or represents I,
n indicates 1 when M is an H atom or an NH ₄ group, and indicates the valence when M is a metal atom. As a metal atom,
Lithium, sodium, potassium, rubidium,
cesium, copper, gold, beryllium, magnesium,
Calcium, strontium, barium, zinc,
cadmium, mercury, aluminum, indium,
Lanthanum, ruthenium, thallium, germanium, tin, lead, antimony, bismuth, chromium, molybdenum, tungsten, manganese, rhenium,
Examples include iron, cobalt, nickel, rhodium, palladium, osmium, iridium, platinum, and cerium. ), halogen-containing metal complexes (e.g.
K ₂ PtCl ₆ , K ₂ PtBr ₆ , HAuCl ₄ , (NH ₄ ) ₂ IrCl ₆ ,
(NH ₄ ) ₃ IrCl ₆ , (NH ₄ ) ₂ RuCl ₆ , (NH ₄ ) ₃ RuCl ₆ ,
(NH ₄ ) ₂ RhCl ₆ , (NH ₄ ) ₃ RhBr ₆ , etc.), onium halides (e.g., tetramethylammonium bromide, trimethylphenylammonium bromide, cetylethyldimethylammonium bromide, 3-methylthiazolium bromide, trimethylbenzyl quaternary ammonium halides such as ammonium bromide, quaternary phosphonium halides such as tetraethyl phosphonium bromide, tertiary sulfonium halides such as benzylethylmethylsulfonium bromide, 1-ethylthiazolium bromide, etc.), halogenation Hydrocarbons (e.g. iodoform, bromoform, carbon tetrabromide, 2-bromo-2-methylpropane, etc.), N-halogen compounds (N-chlorosuccinimide, N-bromosuccinimide, N-
Bromophthalimide, N-bromoacetamide, N-iodosuccinimide, N-bromophthalazinone, N-chlorophthalazinone, N-bromoacetanilide, N,N-dibromobenzenesulfonamide, N-bromo-N-methylbenzene sulfonamide, 1,3-dibromo-4,4-dimethylhydantoin, etc.), and other halogen-containing compounds (e.g., triphenylmethyl chloride, triphenylmethyl bromide, 2-bromobutyric acid, 2-bromoethanol, etc.). be able to. These photosensitive silver salt-forming components and the photosensitive silver halide grains can be used in combination in various methods, and the amount used per 1 m ² of each layer is as follows:
The amount is preferably 0.001 g to 50 g, more preferably 0.1 g to 10 g. The photosensitive silver halide used in the present invention can be optically spectral sensitized to a desired wavelength range using a dye known as a sensitizing dye. Typical spectral sensitizing dyes used in the present invention include, for example, cyanine, merocyanine, complex (triple or quaternary) cyanine, holopolar cyanine, styryl, hemicyanine, oxonol, and the like. Among the cyanine pigments, thiazoline, oxazoline, pyrroline, pyridine, oxazole, thiazole, selenazole,
Those having a basic core such as imidazole are more preferred. Such a nucleus may contain an alkyl group, an alkylene group, a hydroxyalkyl group, a sulfoalkyl group, a carboxyalkyl group, an aminoalkyl group, or an enamine group capable of forming a fused carbocyclic or heterocyclic ring. good. Further, it may be symmetrical or asymmetrical, and the methine chain or polymethine chain may have an alkyl group, phenyl group, enamine group, or heterocyclic substituent. In addition to the above-mentioned basic nucleus, merocyanine dyes have acidic nuclei such as thiohydantoin nucleus, rhodanine nucleus, oxazolidione nucleus, thiazolidinedione nucleus, barbituric acid nucleus, thiazolinthione nucleus, malononitrile nucleus, and pyrazolone nucleus. Good too. These acidic nuclei may be further substituted with an alkyl group, an alkylene group, a phenyl group, a carboxyalkyl group, a sulfoalkyl group, a hydroxyalkyl group, an alkoxyalkyl group, an alkylamine group, or a heterocyclic nucleus. If necessary, these dyes may be used in combination. Furthermore, ascorbic acid derivatives, azaindene cadmium salts,
Organic sulfonic acids, etc., such as U.S. Pat. No. 2,933,390;
A supersensitizing additive that does not absorb visible light, such as those described in the specification of No. 2937089, can be used in combination. The amount of these sensitizing dyes added is 1.times.10.sup. ^-4 mol to 1 mol per mol of photosensitive silver halide. More preferably, it is 1×10 ⁻⁴ mol to 1×10 ⁻¹ mol. The heat-developable photosensitive material of the present invention can be applied to any photosensitive material that forms an image by heat development. Examples include black-and-white types that form a silver image by heat development, and color types that include a dye-providing substance. In this latter color type, there are further monochromatic materials having a single color, for example, a black dye-providing substance or any other monochrome dye-providing substance, and multicolor, for example, heat-developable color photosensitive materials with yellow, cyan, and magenta coloring. can be mentioned. In the color type, a method is usually used in which only the developed dye is transferred to the image receiving member. The present invention exhibits particularly favorable effects when applied to the latter color type. In the black-and-white type in which the heat-developable photosensitive material of the present invention forms a silver image, the photosensitive layer on the support basically contains (1) photosensitive silver halide, (2) reducing agent, and (3)
A binder and, if necessary, (4) an organic silver salt are contained. In addition, in the color type that forms a dye image, basically one photosensitive layer on the support contains (1) photosensitive silver halide, (2) reducing agent, (3) binder, and (5) dye donor. (4) an organic silver salt if necessary. However, these do not necessarily need to be contained in a single photosensitive layer; for example, the photosensitive layer may be divided into two layers, and the components (1), (2), (3), and (4) may be added to one side of the photosensitive layer. A dye-providing substance (5) is contained in a layer, and a dye-providing substance (5) is contained in a layer on the other side adjacent to this photosensitive layer.
They may be contained separately in two or more photosensitive layers as long as they are in a state where they can react with each other. Furthermore, the photosensitive layer may be divided into two or more layers, such as a high-sensitivity layer and a low-sensitivity layer, and may further include one or more photosensitive layers having different color sensitivities. Alternatively, it may have various photographic constituent layers such as an overcoat layer, an undercoat layer, a backing layer, and an intermediate layer. Similar to the heat-developable photosensitive layer of the present invention, coating solutions are prepared for the protective layer, intermediate layer, undercoat layer, back layer, and other photographic constituent layers, using the dipping method, air knife method, curtain coating method, or Patent No.
A photothermographic material can be prepared by various coating methods such as the hopper coating method described in No. 3681294. Furthermore, if desired, two or more layers can be applied simultaneously by the methods described in US Pat. No. 2,761,791 and British Patent No. 837,095. The components used in the photosensitive layer and other photographic constituent layers of the heat-developable photosensitive material of the present invention are coated on a support, and the coating thickness after drying is preferably 1 to 1000 μm, more preferably 3 to 20 μm. . In the heat-developable photosensitive material of the present invention, various organic silver salts can be used, if necessary, for the purpose of increasing sensitivity and improving developability. Examples of organic silver salts used in the heat-developable photosensitive material of the present invention include Japanese Patent Publication Nos. 43-4921 and 44-26582;
No. 45-18416, No. 45-12700, No. 45-22185,
JP-A-49-52626, JP-A No. 52-31728, JP-A No. 52-
Publications such as No. 137321, No. 52-141222, No. 53-36224, and No. 53-37610, as well as U.S. Patent No.
Silver salts of aliphatic carboxylic acids such as silver laurate, myristic acid, etc., as described in the specifications of No. 3330633, No. 3794496, No. 4105451, No. 4123274, No. 4168980, etc. Silver, silver palmitate, silver stearate, silver arachidonate, silver behenate, silver α-(1-phenyltetrazolthio)acetate, etc., silver aromatic carboxylates, such as silver benzoate, silver phthalate, etc. No. 44-26582, 45
-12700, 45-18416, 45-22185, JP-A-52-31728, JP-A-52-137321, JP-A-58-
Silver salts of imino groups such as those described in publications such as No. 118638 and No. 58-118639, such as silver benzotriazole, silver 5-nitrobenzotriazole,
5-chlorobenzotriazole silver, 5-methoxybenzotriazole silver, 5-methylbenzotriazole silver, 4-sulfobenzotriazole silver, 4
-Hydroxybenzotriazole silver, 5-aminobenzotriazole silver, 5-carboxybenzotriazole silver, imidazole silver, benzimidazole silver, 6-nitrobenzimidazole silver, pyrazole silver, urazole silver, 1,2,4-triazole silver, 1H -tetrazole silver, 3-amino-5
- benzylthio 1,2,4-triazole silver,
Satucalin silver, phthalazinone silver, phthalimide silver, etc., 2-mercaptobenzoxazole silver, mercaptooxadiazole silver, 2-mercaptobenzothiazole silver, 2-mercaptobenzimidazole silver, 3-mercapto-4-phenyl-1,2, 4-triazole silver, 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene silver and 5-methyl-7-hydroxy-1,
Examples include 2,3,4,6-pentazaindene silver. Among the above organic silver salts, imino group silver salts are preferred, and silver salts of benzotriazole derivatives are particularly preferred, and silver salts of methylbenzotriazole derivatives and sulfobenzotriazole derivatives are particularly preferred. The organic silver salts used in the present invention may be used alone or in combination of two or more, and isolated ones may be used by dispersing them in a binder by appropriate means, or they may be used in a suitable form. The silver salt may be prepared in a binder and used as is without isolation. The amount of the organic silver salt used is 1 photosensitive silver halide.
Preferably, it is 0.01 to 500 mol per mol,
More preferably, it is 0.1 mol to 100 mol. As the reducing agent used in the heat-developable photosensitive material of the present invention, those commonly used in the field of heat-developable photosensitive materials can be used, such as those disclosed in US Pat.
No. 3761270, No. 3764328, and p-phenylenediamine type and p -Aminophenol type developing agents, phosphoroamide phenol type and sulfonamide phenol type developing agents, and hydrazone type color developing agents. In addition, U.S. Patent No. 3342599, U.S. Patent No. 3719492, and Japanese Unexamined Patent Publication No. 135628/1983
Color developing agent precursors described in No. 54-79035 and the like can also be advantageously used. As a particularly preferable reducing agent, JP-A-56-146133
Examples include reducing agents represented by the following general formula (1) described in No. General formula (1) In the formula, R ¹ and R ² each have a hydrogen atom or a carbon atom number of 1 to 30 (preferably 1), which may have a substituent.
-4) represents an alkyl group, and R ¹ and R ² may be ring-closed to form a heterocycle. R ³ , R ⁴ , R ⁵ and R ⁶ are hydrogen atoms, halogen atoms, hydroxy groups,
Represents an amino group, an alkoxy group, an acylamido group, a sulfonamide group, an alkylsulfonamide group, or an alkyl group having 1 to 30 carbon atoms (preferably 1 to 4) that may have a substituent, and R ³ and R ¹ And R ⁵ and R ² may each be ring-closed to form a heterocycle. M represents an alkali metal atom, an ammonium group, a nitrogen-containing organic base, or a compound containing a quaternary nitrogen atom. The nitrogen-containing organic base in the above general formula (1) is an organic compound containing a nitrogen atom that exhibits basicity capable of forming a salt with an inorganic acid, and particularly important organic bases include amine compounds. Examples of chain amine compounds include primary amines, secondary amines, and tertiary amines, and examples of cyclic amine compounds include pyridine, quinoline, and piperidine, which are well-known examples of typical heterocyclic organic bases. , imidazole and the like. In addition, hydroxylamine,
Compounds such as hydrazine and amidine are also useful as chain amines. In addition, as the salt of the nitrogen-containing organic base, inorganic acid salts of the organic base (eg, hydrochloride, sulfate, nitrate, etc.) as described above are preferably used. On the other hand, examples of the compound containing quaternary nitrogen in the above general formula include salts or hydroxides of nitrogen compounds having a tetravalent covalent bond. Next, preferred specific examples of the reducing agent represented by the general formula (1) are shown below. The reducing agent represented by the above general formula (1) can be prepared by a known method, for example, Heuben-Beil, Mesoden der Organizien Chemie, Band XI/2.
(Houben-Weyl, Methoden der Organischen
Chemie, Band XI/2), pages 645-703. On the other hand, the dye-donating substance is disclosed in JP-A No. 57-179840,
No. 58-58543, No. 59-152440, No. 59-154445
In the case of a compound that releases a dye upon oxidation, a compound that loses the ability to release a dye upon oxidation, a compound that releases a dye upon reduction as shown in the following No. 1, or when obtaining only a silver image without containing a dye-providing substance, , reducing agents such as those described below can also be used. For example, phenols (e.g. p-phenylphenol, p-methoxyphenol, 2,6-di-tert-butyl-p-cresol, N-methyl-
p-aminophenol, etc.), sulfonamidophenols [e.g. 4-benzenesulfonamidophenol, 2-benzenesulfonamidophenol, 2,6-dichloro-4-benzenesulfonamidophenol, 2,6-dibromo-4-(p-aminophenol, etc.) −
toluenesulfonamide) phenol, etc.], or polyhydroxybenzenes (e.g., hydroquinone, tert-butylhydroquinone, 2,6-dimethylhydroquinone, chlorohydroquinone,
carboxyhydroquinone, catechol, 3-carboxycatechol, etc.), naphthols (e.g. α
-naphthol, β-naphthol, 4-aminonaphthol, 4-methoxynaphthol, etc.), hydroxybinaphthyls and methylene bisnaphthols [e.g. 1,1'-dihydroxy-2,2'-binaphthyl, 6,6'-dibromo- 2,2'-dihydroxy1,1'-binaphthyl, 6,6-dinitro-2,
2'-dihydroxy-1,1'-binaphthyl, 4,
4'-dimethoxy-1,1'-dihydroxy-2,
2'-binaphthyl, bis(2-hydroxy-1-naphthyl)methane, etc.], methylenebisphenols [e.g. 1,1-bis(2-hydroxy-3,5
-dimethylphenyl)-3,5,5-trimethylhexane, 1,1-bis(2-hydroxy-3-
tert-butyl-5-methylphenyl)methane,
1,1-bis(2-hydroxy-3,5-di-
tert-butylphenyl)methane, 2,6-methylenebis(2-hydroxy-3-tert-butyl-5
-methylphenyl)-4-methylphenol, α
-Phenyl-α,α-bis(2-hydroxy-
3,5-di-tert-butylphenyl)methane, α
-phenyl-α,α-bis(2-hydroxy-3
-tert-butyl-5-methylphenyl)methane,
1,1-bis(2-hydroxy-3,5-dimethylphenyl)-2-methylpropane, 1,1,5,
5-tetrakis(2-hydroxy-3,5-dimethylphenyl)-2,4-ethylpentane, 2,
2-bis(4-hydroxy-3,5-dimethylphenylpropane, 2,2-bis(4-hydroxy-3-methyl-5-tert-butylphenyl)propane, 2,2-bis(4-hydroxy-3 ,5-
di-tert-butylphenyl)propane, etc.], ascorbic acids, 3-pyrazolidones, pyrazolones, hydrazones, and paraphenylenediamines. These reducing agents can be used alone or in combination of two or more. The amount of reducing agent used depends on the type of photosensitive silver halide used, the type of organic acid silver salt, and the types of other additives, but it is usually per mol of photosensitive silver halide.
It ranges from 0.01 to 1500 mol, preferably from 0.1 to 1500 mol.
It is 200 moles. Examples of the binder used in the heat-developable photosensitive material of the present invention include synthetic or natural polymers such as polyvinyl butyral, polyvinyl acetate, ethyl cellulose, polymethyl methacrylate, cellulose acetate butyrate, polyvinyl alcohol, polyvinylpyrrolidone, gelatin, and phthalated gelatin. One or more molecular substances can be used in combination. In particular, it is preferable to use gelatin or a derivative thereof in combination with a hydrophilic polymer such as polyvinylpyrrolidone or polyvinyl alcohol, and more preferably the following binder described in Japanese Patent Application No. 104249/1982. This binder includes gelatin and vinylpyrrolidone polymer. The vinylpyrrolidone polymer may be polyvinylpyrrolidone, which is a homopolymer of vinylpyrrolidone, or one or two of other monomers copolymerizable with vinylpyrrolidone.
Copolymers with the above (including graft copolymers)
It may be. These polymers can be used regardless of their degree of polymerization. The polyvinylpyrrolidone may be a substituted polyvinylpyrrolidone, with preferred polyvinylpyrrolidone having a molecular weight of 1000
~400,000. Other monomers copolymerizable with vinylpyrrolidone include (meth)acrylic acid esters such as acrylic acid, methacrylic acid and alkyl esters thereof, vinyl alcohols, vinyl imidazoles, (meth)acrylamides, and vinyl carbinols. , vinyl monomers such as vinyl alkyl ethers, etc., but it is preferable that polyvinylpyrrolidone accounts for at least 20% (weight %, same hereinafter) of the composition ratio. Preferred examples of such copolymers have a molecular weight of
5,000 to 400,000. Gelatin may be treated with lime or acid, and may be ossein gelatin, pitgskin gelatin, hydrogelatin, or modified gelatin obtained by esterifying or phenylcarbamoylating these gelatins. In the above binder, gelatin preferably accounts for 10 to 90%, more preferably 20 to 60%, and vinylpyrrolidone accounts for 5 to 90%, more preferably 10 to 80% of the total binder amount. %. The binder may contain other polymeric substances, such as gelatin and a mixture of polyvinylpyrrolidone with a molecular weight of 1,000 to 400,000 and one or more other polymeric substances, gelatin and a polymer with a molecular weight of 5,000 to 400,000.
A mixture of the vinyl pyrrolidone copolymer and one or more other polymeric substances is preferred. Other polymeric substances that may be used include polyvinyl alcohol, polyacrylamide, polymethacrylamide, polyvinyl butyral, polyethylene glycol, polyethylene glycol ester, or proteins such as cellulose derivatives, and polysaccharides such as starch and gum arabic. Examples include natural substances. These range from 0 to 85%, preferably from 0 to 85%.
It may contain 70%. Note that the vinyl pyrrolidone polymer may be a crosslinked polymer, but in this case, it is preferable to crosslink it after coating it on the support (including the case where the crosslinking reaction progresses by leaving it naturally). The amount of binder used is usually 0.05 g to 50 g, preferably 0.1 g to 10 g per m ² per layer. Examples of the support used in the heat-developable photosensitive material of the present invention include polyethylene film, cellulose acetate film, polyethylene terephthalate film, synthetic plastic film such as polyvinyl chloride, and photographic base paper, printing paper, baryta paper, and resin coated paper. Examples include paper supports such as the above, and supports prepared by providing the above-mentioned synthetic plastic film with a reflective layer. In addition to the above-mentioned components, various additives may be added to the heat-developable photosensitive material of the present invention, if necessary. For example, as a development accelerator, US Pat.
No. 3220840, No. 3531285, No. 4012260, No. 4060420, No. 4088496, No. 4207392, RD No. 15733, No. 15734, No. 15776,
Alkali releasing agents such as urea and phanidium trichloroacetate described in JP-A-56-130745 and JP-A-56-132332, organic acids as described in JP-A-45-12700, - as described in U.S. Pat. No. 3,667,959 CO−,−
Non-aqueous polar solvent compounds having SO ₂ -, -SO- groups, melt formers described in U.S. Pat. No. 3,438,776, polyalkylene glycols described in U.S. Pat. . In addition, as a color toning agent, for example, JP-A No. 46-4928,
No. 46-6077, No. 49-5019, No. 49-5020, No. 49
−91215, No. 49-107727, No. 50-2524, No.
No. 50-67132, No. 50-67641, No. 50-114217,
No. 52-33722, No. 52-99813, No. 53-1020,
No. 53-55115, No. 53-76020, No. 53-125014
No. 54-156523, No. 54-156524, No. 54-
No. 156525, No. 55-156526, No. 55-4060, No. 55
Publications such as -4061 and 55-32015, as well as West German Patent Nos. 2140406, 2147063, and 2220618
No., U.S. Patent No. 3080254, U.S. Patent No. 3847612, U.S. Patent No.
Phthalazinone, phthalimide, pyrazolone, quinazolinone, N-hydroxynaphthalimide, benzoxazine, naphthoxazinedione, which is a compound described in the specifications of No. 3782941, No. 3994732, No. 4123282, No. 4201582, etc. , 2,3-dihydro-phthalazinedione, 2,
3-dihydro-1,3-oxazine-2,4-dione, oxypyridine, aminopyridine, hydroxyquinoline, aminoquinoline, isocarbostyryl, sulfonamide, 2H-1,3-benzothiazine-2,4-(3H) dione, benzotriazine, mercaptotriazole, dimercaptotetrazapentalene, phthalic acid, naphthalic acid, phthalamic acid, etc., mixtures of one or more of these with imidazole compounds, and phthalic acid, naphthalic acid, etc. Examples include mixtures of at least one acid or acid anhydride and a phthalazine compound, and combinations of phthalazine and maleic acid, itaconic acid, quinolinic acid, gentisic acid, and the like. Also, JP-A-58-189628, JP-A No. 58-189628;
3-amino-5-mercapto-1,2,4-triazoles and 3-acylamino-5-mercapto-1,2,4-triazoles described in Japanese Patent No. 193460 are also effective. Furthermore, as antifoggants, for example,
Special Publication No. 11113, No. 49-90118, No. 49-
No. 10724, No. 49-97613, No. 50-101019, No. 49
-130720, 50-123331, 51-47419,
No. 51-57435, No. 51-78227, No. 51-104338
No. 53-19825, No. 53-20923, No. 51-
No. 50725, No. 51-3223, No. 51-42529, No. 51-
Publications such as No. 81124, No. 54-51821, and No. 55-93149, as well as British Patent No. 1455271 and US Patent No.
3885968, 3700457, 4137079, 4138265, and West German Patent No. 2617907, or oxidizing agents (for example, N-halogen acetamide,
N-halogenosuccinimide, perchloric acid and its salts, inorganic peroxides, persulfates, etc.), or
Acids and their salts (e.g., sulfuric acid, lithium laurate, rosin, diterpenic acid, thiosulfonic acid, etc.), or sulfur-containing compounds (e.g.,
mercapto compound releasing compound, thiouracil,
Disulfide, simple sulfur, mercapto-1,
2,4-triazole, thiazolinthione, polysulfide compound, etc.), others, oxazoline,
Examples include compounds such as 1,2,4-triazole and phthalimide. Furthermore, thiol (preferably a thiophenol compound) compound described in JP-A-59-111636 is also effective as another antifoggant. In addition, as other anti-fogging agents,
Hydroquinone derivatives described in No. 56506 (e.g.
di-t-octylhydroquinone, dodecanylhydroquinone, etc.), hydroquinone derivatives and benzotriazole derivatives (e.g., 4-sulfobenzotriazole,
-carboxybenzotriazole, etc.) can be preferably used in combination. In addition, as a stabilizer, a printout preventive agent may be used at the same time, especially after processing.
No. 45228, No. 50-119624, No. 50-120328, No. 45228, No. 50-119624, No. 50-120328, No.
Halogenated hydrocarbons described in Publication No. 53-46020, specifically tetrabromobutane, tribromoethanol, 2-bromo-2-tolylacetamide, 2-bromo-2-tolylsulfonylacetamide, 2-tribromo Methylsulfonylbenzothiazole, 2,4-bis(tribromomethyl)-
Examples include 6-methyltriazine. Also, JP-A-46-5393, JP-A-50-54329,
Post-treatment may be carried out using a sulfur-containing compound as described in each publication of No. 50-77034. Furthermore, U.S. Patent No. 3301678, U.S. Patent No. 3506444
The isothiuronium-based stabilizer precursor described in the specifications of No., No. 3824103, and No. 3844788, as well as U.S. Pat. Nos. 3669670 and 4012260
It may also contain activator stabilizer precursors and the like as described in No. 4,060,420 and the like. Furthermore, a water release agent such as sucrose, NH ₄ Fe (SO ₄ ) _{2.12H 2} O, etc. may be used.
Heat development may be carried out by supplying water as in No. 132332. In addition to the above-mentioned components, the heat-developable photosensitive material of the present invention may further contain various additives and coating aids, such as antihalation dyes, optical brighteners, hardeners, antistatic agents, plasticizers, and spreading agents. Agents etc. can be added. When the heat-developable photosensitive material of the present invention is a color type, a dye-providing substance is used. Dye-providing substances that can be used in the present invention will be explained below. The dye-donating substance may be any substance as long as it participates in the reduction reaction of the photosensitive silver halide and/or the organic silver salt used as necessary and can form or release a diffusible dye as a function of the reaction. Depending on its reaction form, negative-acting dye-donors that act in a positive function (i.e.
A positive dye-donor acting on a negative function (i.e., a positive dye image when using negative-working silver halide) can be classified as Negative dye-donating substances are further classified as follows.

[Table] Compounds that form diffusible dyes

Claims (1)

[Claims] 1. The photosensitive silver halide emulsion of the heat-developable photosensitive material is a photosensitive silver halide grain containing silver iodide, and the silver iodide content in the inner layer of the grain is 4 mol% to 7 mol%, 1. A heat-developable photosensitive material comprising core/shell type photosensitive silver halide grains having a silver iodide content in the surface layer of 0 mol % to 6 mol % and lower than the silver iodide content in the inner layer.