JPH0723957B2 - Photothermographic material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a photothermographic material, and more particularly to a photothermographic material having small desensitization by heat development and high sensitivity.

BACKGROUND OF THE INVENTION A method of performing a developing process for obtaining an image by a dry heat treatment has many advantages in comparison with a conventional wet method in terms of processing time, cost, and concern about pollution.

Regarding the photothermographic material capable of performing the above-mentioned developing step by dry heat treatment, for example, Japanese Patent Publication Nos. 43-4921 and 43-4924.
The publication discloses that, and a black and white type photothermographic material comprising an organic silver salt, a silver halide and a reducing agent is disclosed.

Attempts have been made to improve the heat-developable photosensitive material and obtain a color image by various methods.

For example, JP-A-57-179840, 57-186744, 57-19
8458, 57-207250, 58-40551, 58-58543
No. 58-79247, 59-12431, 59-22049.
No. 59-68730, 59-124339, 59-124333
No. 59-124331, 59-159159, 59-181345.
No. 59-159161, 58-116537, 58-123533.
No. 58-149046 and No. 58-14947.

The basic constitution of a color type photothermographic material for obtaining this color image is composed of a photosensitive element and an image receiving element, and the photosensitive element basically comprises a photosensitive silver halide, an organic silver salt, a reducing agent (hereinafter, a developer). (Also referred to as a), a dye-providing substance, and a binder. In the present invention, only the photosensitive element is narrowly interpreted as a photothermographic material.

In the former black-and-white type, light information is given to the photosensitive silver halide by image exposure, and in the heat development, the exposed photosensitive silver halide and the reducing agent in the photosensitive layer are present in the vicinity thereof. The catalytic action of silver halide causes a redox reaction to generate silver, and the exposed portion of the photosensitive layer is blackened to form a silver image.

Further, in the color type, light information is given to the photosensitive silver halide by imagewise exposure, and in thermal development,
Under the action of the reducing agent, the physical dissolution is carried out between the organic silver salt and the photosensitive silver halide according to the optical information, and the acting or not acting reacts with the dye-donor substance. By doing so, the dye forming an image is released or formed. The image forming dye obtained by heat development is transferred to an image receiving element to form an image.

In the above-mentioned silver image forming black-and-white type and color type photothermographic materials, an image is usually formed by heat development after exposure or at the same time as exposure.
Since it is heated to a high temperature of 80 ° C or higher, it has various effects on the photosensitive silver halide. One of the greatest effects is desensitization by heat development. That is, the sensitivity of the exposed photothermographic material when heat-developed at a temperature of 80 ° C or higher is significantly higher than the sensitivity when developed at a temperature of 40 ° C or lower with an ordinary wet photographic processing solution. It became clear that it would decrease. Further, it was also clarified that in the photothermographic material containing the sensitizing dye, the desensitization due to the heat development was remarkable.

Regarding the desensitization phenomenon due to the heat development, it is considered that a part of the latent image formed on the exposed photosensitive silver halide grains is thermally bleached by the heat development, but the detailed mechanism thereof is not clear.

Further, addition of a sensitizing dye to silver halide is to impart high sensitivity to visible light to infrared light to silver halide, which is an essential component in a photothermographic material. Improvement of undesired desensitization has been desired.

The present inventors have found that the above-mentioned desensitization in the photothermographic material uses a combination of two specific types of sensitizing dyes, further contains silver iodide in a specific range, and has an average grain size of a specific value. The present invention has been found to be improved by using the following photosensitive silver halide grains and has been accomplished the present invention.

Therefore, an object of the present invention is to reduce the desensitization by heat development,
It is to provide a high-sensitivity photothermographic material.

[Construction of the Invention] The above-mentioned object of the present invention has a silver iodide content of 4 to 40 mol% in at least one of the silver halide emulsion layers of the photothermographic material.
And a photosensitive silver halide grain having an average particle size of 0.4 μm or less and at least one compound represented by the following general formula (I) in combination with at least one compound represented by the following general formula (II). , A photothermographic material substantially free of an alkali agent or an alkali agent precursor.

General formula (I)Where R₁Is a hydrogen atom, an alkyl group, an aryl group or
Represents a telocyclic group, R₂And R₃Are alkyl groups
Represent. Y₁And Y₂Is sulfur atom or selenium atom, respectively
Represents a child. Z₁, Z₂, Z₃And Z_FourAre hydrogen atoms,
Halogen atom, hydroxyl atom, alkoxy group, reed
Group, alkoxycarbonyl group, alkoxycarbonyl group
Amino group, acylamide group, aryl group, alkyl group
Or represents a cyano group. However, Z₁And Z₂Or Z₃And Z_FourThroat
Either one or both
May form a ring. X₁ Represents an anion, and m represents
Represents an integer of 0 or 1.

General formula (II)Where R_Four, R_Five, R₆And R₇Is a hydrogen atom or
Represents a rukyll group. Y₃Is a nitrogen atom, a sulfur atom or selenium
Represents a hydrogen atom, but Y₃Is a sulfur atom or a selenium atom
When R above_FourShall not be included. Z_Five, Z₆, Z₇and
Z₈Are hydrogen atom, halogen atom, hydroxyl
Group, alkoxy group, acyl group, acylamido group, acyl
Oxy group, alkoxycarbonyl group, aryloxy group
Rubonyl group, alkoxycarbonylamino group, aryl
Represents a group, an alkyl group, a cyano group or a sulfonyl group
You However, Z_FiveAnd Z₆Or Z₇And Z₈Either one or
Both may be linked together to form a ring.
Yes. X₂ Represents an anion, and n is an integer of 0 or 1.
Represent.

[Specific Structure of the Invention] The compounds represented by the general formula (I) and the general formula (II) (hereinafter referred to as the compound of the present invention) used in the present invention are sensitizing dyes.

In the general formula (I), the alkyl group represented by R ₁ is preferably a lower alkyl group, and examples thereof include a methyl group, an ethyl group and a propyl group, with an ethyl group being preferred. The aryl group includes a phenyl group, and the heterocyclic group includes a furyl group and a thiofuryl group.

Next, the alkyl group represented by R ₂ and R ₃ is preferably a lower alkyl group, for example, a methyl group, an ethyl group, a butyl group and a substituent such as a sulfoethyl group,
There are carboxypropyl group, sulfobutyl group and the like, but sulfopropyl group is preferable.

Further, examples of the halogen atom represented by Z ₁ , Z ₂ , Z ₃ and Z ₄ include chlorine, bromine, iodine and fluorine atoms, and at least one of Z ₁ and Z ₂ , Z ₃ and Z ₄ At least one of the above is preferably a chlorine atom. Examples of the alkoxy group include groups such as methoxy, ethoxy, propoxy and butoxy, examples of the acyl group include groups such as an acetyl group, and examples of the acylamide group include groups such as acetamide and propionamide. The alkoxycarbonyl group includes groups such as ethoxycarbonyl and propoxycarbonyl, and the alkoxycarbonylamino group includes groups such as ethoxycarbonylamino, propoxycarbonylamino and butoxycarbonylamino, and the aryl group includes Is, for example, a group such as phenyl or tolyl, and the alkyl group is preferably a lower alkyl group, for example, a group such as methyl, ethyl or propyl.

And Z₁And Z₂Or Z₃And Z_FourEither one or that
The ring formed by connecting both is a benzene ring.
But Z₁And Z₂And Z₃And Z_FourTogether form a benzene ring
It is preferable. This benzene ring has more substituents
May be. Furthermore, in the general formula (I), X₁
Examples of the anion represented by are chloride, bromide, and iodide.
Compound, thiocyanate, sulfamate, methylsulf
, Ethyl sulphate, perchlorate, p-to
Ruene sulfonate and the like.

In the general formula (II), the alkyl group represented by R ₄ , R ₅ , R ₆ and R ₇ is preferably a lower alkyl group, for example, sulfoethyl having a substituent such as methyl, ethyl and butyl. There are groups such as carboxypropyl and sulfobutyl.

Furthermore, Z_Five, Z₆, Z₇And Z₈But each represents
Examples of the nitrogen atom include chlorine, bromine, iodine and fluorine.
There are atoms, and as the alkoxy group, for example, methoxy,
There are various groups such as ethoxy, propoxy, butoxy, etc.
Examples of the acetyl group include an acetyl group, an acylamido group
As, for example, acetamide, propionamide, etc.
There are various groups of
There are various groups such as xy and propionoxy groups, and alkoxy groups.
Examples of the carbonyl group include ethoxycarbonyl and
There are various groups such as ropoxycarbonyl.
A phenyloxy group is phenoxycarbonyl.
Examples of the coxycarbonylamino group include ethoxycarboxyl.
Rubonylamino, propoxycarbonylamino, butoki
There are groups such as cycarbonylamino, and as an aryl group
Is a group such as phenyl, tolyl, etc.
The group is preferably a lower alkyl group such as methyl,
Examples of groups such as ethyl and propyl, and sulfonyl groups include
Killsulfonyl group, aminosulfonyl group, morpholinos
Examples include sulfonyl, piperidinosulfonyl groups, etc.
it can. And Z_FiveAnd Z₆Or Z₇And Z₈There is one of
Or as a ring formed by connecting both of them, benze
Ring, and even if this benzene ring has further substituents
Good. Furthermore, in the general formula (II), X₂ Is the table
For example, chloride, bromide, iodide, etc.
Thing, thiocyanate, sulfamate, methylsulfate
, Ethyl sulphate, perchlorate, p-tolu
Ensulfonate and the like.

The representative compounds of the general formula (I) used in the present invention are shown below, but the present invention is not limited thereto.

(Exemplified compound) In the present invention, more preferable compounds among the compounds represented by the general formula (II) can be represented by the following general formulas (II A) and (II B).

General formula (II A)Where R₈, R₉, R_TenAnd R₁₁Is a lower alkyl group (eg
Have substituents such as methyl, ethyl, and butyl,
For example sulfoethyl, carboxypropyl, sulfobutyl
Group of each group), such as ethyl, sulfopropyl,
Rufobutyl groups are preferred. Z₉, Z_Ten, Z₁₁And Z₁₂
Are hydrogen atom and halogen atom (for example, chlorine, odor)
Examples include elemental, iodine, and fluorine atoms, but Z₉, Z_Ten, Z
₁₁, Z₁₂It is preferable that all are chlorine atoms. ), Hydro
A xyl group, an alkoxy group (eg, methoxy, ethoxy,
Examples include propoxy and butoxy groups.₉And Z_Ten
And Z₁₁And Z₁₂At least one of each is a butoxy group
Is preferred. ), An acyl group (eg acetyl
Groups), acylamido groups (eg acetamide, propio
Amide, butyramide groups, etc.), acyloxy groups
(For example, acetoxy and propionoxy groups)
Lucoxycarbonyl group (eg ethoxycarbonyl,
Ropoxycarbonyl groups etc.), Aryloxycarbo
Nyl group (eg phenoxycarbonyl group), alkoxy
Cycarbonylamino group (eg ethoxycarbonylamido)
No, propoxycarbonylamino, butoxycarbonyl
Amino groups, etc.), aryl groups (eg phenyl groups)
Etc.), lower alkyl groups (eg methyl, trifluorometh
Cyl, ethyl, propyl, etc.), sulfonyl group (a)
Rucylsulfonyl group, aminosulfonyl group, morpholino
Sulfonyl, piperidinosulfonyl groups, etc.), sia
No group (Z₉And Z_TenAnd Z₁₁And Z₁₂At least 1 of each
It is preferred that one is a cyano group. ) Etc. Also Z₉
And Z_TenOr Z₁₁And Z₁₂Either one or both
May be connected to each other to form a ring.
Examples of the ring include a benzene ring. X₃ Is anion
(For example, chloride, bromide, iodide, thiocyanate,
Rufamate, methyl sulphate, ethyl sulphate
, Perchlorate, p-toluene sulfonate, etc.)
Where l represents an integer of 0 or 1.

General formula (II B)Where Y_FourRepresents a sulfur atom or a selenium atom, R₁₂, R
₁₃And R₁₄Are each a lower alkyl group (eg methyl
It has a substituent including each group of le, ethyl and butyl,
For example sulfoethyl, carboxypropyl, sulfobutyl
Group of each group), preferably ethyl and sul
Hoppropyl. Z₁₃, Z₁₄, Z₁₅And Z₁₆Is that
Hydrogen atom, halogen atom (for example, chlorine, bromine, iodine,
Fluorine atoms), hydroxyl groups, alkoxy groups (eg
For example, methoxy, ethoxy, propoxy, butoxy groups
Etc.), acylamido groups (eg acetamide, propion
Amide groups), acyloxy groups (eg acetoxy)
Si, propionoxy groups, etc.), alkoxycarbonyl
Group (eg ethoxycarbonyl, propoxycarbonyl
Groups, etc.), alkoxycarbonylamino groups (eg
Ethoxycarbonylamino, propoxycarbonylami
No, butoxycarbonylamino groups, etc.), aryl groups
(Eg phenyl), lower alkyl (eg methyl)
Group of trifluoromethyl, ethyl, propyl
Etc.), sulfonyl group (alkylsulfonyl group, dimethyl
Aminosulfonyl group, etc.) and the like. Also Z₁₃And Z₁₄Well
Or Z₁₅And Z₁₆Either one or both
Each may be connected to each other to form a ring.
For example, there is a benzene ring. And Z₁₃And Z₁₄Are connected
Form a benzene ring, and Z₁₅And Z₁₆At least
It is preferable that one of them is methyl trifluoride. X_Four Is
Anions (eg chloride, bromide, iodide, thiocyanate
Salt, sulfamate, methylsulfate, ethylsa
Luffate, perchlorate, p-toluenesulfonate
Etc.) and p is an integer of 0 or 1. However
However, when the compound forms an intramolecular salt, p represents 0.
You

The representative examples of the compounds represented by the above general formulas (II A) and (II B) of the present invention are shown below, but the present invention is not limited thereto.

The compounds of the present invention (represented by the above general formulas (I) and (II)) are disclosed in JP-A-49-114419 and JP-B-55-15, respectively.
No. 69, No. 56-39460, etc., and the compound of the present invention can also be synthesized according to the publication.

In the present invention, spectral sensitization is carried out by adding the compound of the present invention to the silver halide emulsion containing the photosensitive silver halide grains of the present invention described later.

The compound of the present invention may be added at any stage such as at the start of chemical ripening (also referred to as second ripening) of the silver halide emulsion, during or after ripening, or at an appropriate time prior to coating the emulsion. .

Further, the order of addition when the compounds of the present invention are added in combination may be the same or different, but the same time is preferable.

As the method for adding the compound of the present invention to the silver halide emulsion, various methods conventionally used in the photographic industry can be applied. For example, as described in US Pat. No. 3,469,987, the compound of the present invention may be dissolved in an organic solvent, the solution may be dispersed in a hydrophilic colloid, and the dispersion may be added to an emulsion. Further, the compound of the present invention is
They can be individually dissolved in the same or different solvents and these solutions mixed prior to addition to the emulsion or added separately.

As the solvent used for dissolving the compound of the present invention, water-miscible organic solvents such as methyl alcohol, ethyl alcohol and acetone are preferably used.

When the compound of the present invention is added to a silver halide emulsion, the addition amount is 1 × 10 ⁻ per mol of photosensitive silver halide in each of the compound of the general formula (I) and the compound of the general formula (II). ^{5 to} 2.5 × 10 ^-2 mol is preferable, and 1.0 × 10 ^{-4 to} 1.0 × 10 ^-3 mol is more preferable. The mixing ratio of the compound represented by the general formula (I) and the compound represented by the general formula (II) is such that when the compound represented by the general formula (I) is 1, the compound represented by the general formula (II) is
It is in the range of 0.1 to 10.

In the present invention, the compound of the present invention may be used in combination with a compound used as another sensitizing dye or a compound used as a supersensitizer.

The photosensitive silver halide grain used in the present invention has a silver iodide content of 4 mol% to 40 mol%, and more preferably a silver iodide content of 4 mol% to 20 mol%.

The photosensitive silver halide grains used in the present invention have an average particle size of 0.4 μm or less, more preferably 0.01 μm to 0.4 μm.
μm, and more preferably 0.05 μm to 0.4 μm.

In the present invention, the average particle size of the photosensitive silver halide grains means the diameter of spherical silver halide grains, and the projected image of the same area in the case of cubic or non-spherical grains. It is an average value of diameters when converted into a circular image, and when the individual particle diameter thereof is ri and the number thereof is ni, is defined by the following formula.

The above particle size can be measured by various methods generally used in the technical field for the above purpose. As a typical method, a love-round “particle size analysis method”, ASTM Symposium on Light Microscopy, 1955, pp. 94-122 or “Theory of Photographic Process” by Mies and James,
The third edition, published by Macmillan, Inc. (1966), Chapter 2. This particle size can be measured from the projected area of the particle using an approximate diameter.

If the particles are of substantially uniform shape, the particle size distribution can be fairly accurately expressed as a diameter or projected area.

In the photosensitive silver halide used in the present invention, other silver halide components of the photosensitive silver halide containing silver iodide are not particularly limited, but preferred silver halide components are silver iodobromide. , And silver chloroiodobromide.

The photosensitive silver halide containing silver iodide used in the present invention is described by P. Grafkides, Himmy Eto Physik Photography (published by Paul Montel) (P. Montel).
Glafkides, Chimie et Physique Photographique, Paul M
ontel) (1967), G. E. Duffin, Photographic Emulsion Chemistry (published by The Focal Press) (GFDuffin, Photographic Emulsi)
on Chemistry, The Focal Press) (1966), Buj El Zelikmann et al., Making and Coating Photographic Emulsion (published by The Focal Press) (VLZelikman et al, Making and Coa)
ting Photographic Emulsion, The Focal Press) (1964
Year) and the like.

That is, any of the acidic method, the neutral method, the ammonia method and the like may be used, but the ammonia method is particularly suitable. As the method of reacting the soluble silver salt and the soluble halogen salt, any of a one-sided mixing method, a simultaneous mixing method, a combination thereof and the like may be used. Further, a reverse mixing method in which silver halide grains are formed in the presence of excess silver ions can also be used. As a method of simultaneous mixing, it is also possible to use a controlled double jet method in which the pAg of the solution in the reaction vessel in which silver halide is produced is arbitrarily controlled and the addition rate of the silver and halogen solutions is controlled. According to the method, a so-called monodisperse silver halide emulsion in which individual crystal forms and grain sizes of silver halide grains are nearly uniform can be obtained.

In the present invention, the above-mentioned monodisperse silver halide emulsion has a grain size distribution in which the variation in grain size of silver halide grains contained in the emulsion is below a certain ratio with respect to the average grain size. I have what I have. The grain size distribution of a photosensitive silver halide emulsion (hereinafter referred to as a monodisperse emulsion), which is composed of grains in which the grain forms of the light-sensitive silver halide are uniform and whose variation in grain size is small, shows almost a normal distribution. The deviation can be easily calculated and the relational expression When the breadth of distribution is defined by, the preferable breadth of distribution of the photosensitive silver halide grains used in the present invention is 15% or less, more preferably 10% or less. Is to have.

More preferred photosensitive silver halide grains used in the present invention are core / shell type having a surface latent image type shell.

The core / shell type photosensitive silver halide emulsion more preferably used in the present invention can be produced by coating a monodisperse photosensitive silver halide grain as a core with a shell.

To make the core monodisperse silver halide grains, grains having a desired size can be obtained by the double jet method while keeping pAg constant. Further, a silver halide emulsion containing a highly monodisperse photosensitive silver halide is disclosed in JP-A-54
The method described in −48521 can be applied. In a preferred embodiment of the method, a method of adding an aqueous potassium iodobromide-gelatin solution and an aqueous ammoniacal silver nitrate solution to an aqueous gelatin solution containing silver halide seed grains while changing the addition rate as a function of time. Is manufactured by. At this time, time function of addition rate, pH, pH
By appropriately selecting g, temperature, etc., a silver halide emulsion containing highly monodisperse core silver halide grains can be obtained.

By sequentially growing the shell according to the method for producing a monodisperse emulsion using the monodisperse core particles as described above,
A silver halide emulsion containing a monodisperse core / shell type photosensitive silver halide preferably used in the present invention can be obtained.

In the core / shell type photosensitive silver halide more preferably used in the present invention, the thickness of the shell coating the core is preferably 0.05% to 90%, and more preferably 1% to 80% of the silver halide grain size. Is the range. In the silver halide composition of the core, the silver iodide content is 4 mol% to 20
Mol% is preferable, and in the silver halide composition of the shell, the content of silver iodide is preferably 0 mol% to 6 mol%.
More preferably, it is a core / shell type silver halide in which the silver iodide content of the core is 2 mol% or more higher than the silver iodide content of the shell.

The photosensitive silver halide emulsion containing a photosensitive silver halide used in the present invention may be chemically sensitized by any method in the photographic art. Examples of the sensitizing method 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 grains, a photosensitive silver salt-forming component may be allowed to coexist with an organic silver salt described below to form photosensitive silver halide on a part of the organic silver salt. it can. As the photosensitive silver salt forming component used in this preparation method, an inorganic halide, for example, a halide represented by MXn (wherein M represents an H atom, an NH ₄ group or a metal atom, and X represents Cl, Br Or I,
n is 1 when M is an H atom or NH ₄ group, and its valence when M is a metal atom. As the 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, chrome,
Molybdenum, tungsten, manganese, rhenium, iron,
Examples thereof include cobalt, nickel, rhodium, palladium, osmium, iridium, platinum and cerium. ),
Halogen-containing metal complexes (eg K ₂ PtCl ₆ , K ₂ PtBr ₆ , HAuC
l ₄ , (NH ₄ ) ₂ IrCl ₆ , (NH ₄ ) ₃ IrCl ₆ , (NH ₄ ) ₂ RuCl ₆ , (N
H ₄ ) ₃ RuCl ₆ , (NH ₄ ) ₂ RhCl ₆ , (NH ₄ ) ₃ RhBr ₆ etc.), onium halides (eg, tetramethylammonium bromide, trimethylphenylammonium bromide, cetylethyldimethylammonium bromide, 3-methylthia Quaternary ammonium halides such as zolium bromide and trimethylbenzyl ammonium bromide,
Quaternary phosphonium halides such as tetraethylphosphonium bromide, benzylethylmethylsulfonium bromide, tertiary sulfonium halides such as 1-ethylthiazolium bromide, etc., halogenated hydrocarbons (eg iodoform, bromoform, tetra Carbon bromide, 2-bromo-2-methylpropane, etc., N-halogen compounds (N-chlorosuccinimide, N-bromosuccinimide, N-bromophthalimide, N-bromoacetamide, N-iodosuccinimide, N -Promophthalazinone, N-chlorophthalazinone, N-bromoacetanilide, N, N-dibromobenzenesulfonamide, N-bromo-N-methylbenzenesulfonamide,
1,3-dibromo-4,4-dimethylhydantoin etc.) and other halogen-containing compounds (eg triphenylmethyl chloride, triphenylmethyl bromide, 2-bromobutyric acid, 2-bromoethanol etc.) and the like. .

These photosensitive silver salt-forming components and photosensitive silver halide grains can be used in combination in various methods, and the amount used is preferably 0.001 g to 50 g per 1 m ² , more preferably, It is 0.1g-10g.

The photothermographic material of the present invention uses a photosensitive silver halide having a silver iodide content of 4 to 40 mol% and an average grain size of 0.4 .mu.m or less as described above. At least one of the compounds represented by the formula (II) and at least one of the compounds represented by the general formula (II) are used in combination.

The photothermographic material of the present invention can be applied to all photothermographic materials that form an image by heat development. Examples thereof include black and white type which forms a silver image by heat development and color type which has a dye-donor substance. In this latter color type, a heat-developable color light-sensitive material is further provided in a single color, for example, a black dye-donor substance or any other single-color dye-donor substance for monochrome, and in a multicolor state, for example, yellow, cyan and magenta. Is mentioned. In the color type, a method of transferring only the colored dye to the image receiving member is usually used.

In the present invention, particularly preferable effects are exhibited when the latter color type is applied.

In the black and white type in which the photothermographic material of the present invention forms a silver image, (1) a photosensitive silver halide and (2) a reduction are basically contained in a photosensitive layer which is a silver halide emulsion layer on a support. An agent and (3) a binder, and further (4) an organic silver salt, if necessary.

In the color type which forms a dye image, basically, (1) a photosensitive silver halide, (2) a reducing agent, in a photosensitive layer which is one silver halide emulsion layer on a support,
(3) Binder, (5) Dye donating substance, and if necessary, (4) Organic silver salt are contained. However, these do not necessarily have to be contained in a single photosensitive layer. For example, the photosensitive layer is divided into two layers, and (1), (2),
If the components (3) and (4) are contained in the photosensitive layer on one side and the dye-donor (5) is contained in the layer on the other side adjacent to the photosensitive layer, as long as they can react with each other. It may be contained separately in two or more photosensitive layers.

In addition, the photosensitive layer may be divided into two or more layers such as a high-sensitivity layer and a low-sensitivity layer, and may have one or more photosensitive layers having different color sensitivities. 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, a coating solution is prepared for each of the protective layer, the intermediate layer, the undercoat layer, the back layer, and the other photographic constituent layers, and the dipping method, the air knife method, the curtain coating method or the US method is used. The photothermographic material can be prepared by various coating methods such as the hopper coating method described in Japanese Patent No. 3,681,294.

Furthermore, if desired, two or more layers can be coated 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 photothermographic material of the present invention are coated on a support, and the thickness of coating is preferably 1 to 1,000 μm after drying, more preferably 3 to 20 μm. is there.

In the photothermographic 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 the organic silver salt used in the photothermographic material of the present invention include JP-B Nos. 43-4921, 44-26582, and 45-18416.
No. 45-12700, No. 45-22185, JP-A-49-52626
No. 52-31728, No. 52-137321, No. 52-141222
Nos. 53-36224 and 53-37610 and the like, and U.S. Pat.Nos. 3,330,633, 3,794,496 and 4,
105,451, 4,123,274, silver salts of aliphatic carboxylic acids as described in each specification such as 4,168,980, for example, laurate, silver myristate, silver palmitate, silver stearate, Arachidonate, silver behenate,
Aromatic silver carboxylates such as α- (1-phenyltetrazolethio) acetate, for example, silver benzoate, silver phthalate, etc., JP-B-44-26582, JP-B-45-12700, and JP-B-45-18416.
No. 45-22185, JP-A No. 53-31728, and No. 52-137321.
JP-A-58-118638 and JP-A-58-118639, silver salts of imino groups such as silver benzotriazole, silver 5-nitrobenzotriazole, 5-
Chlorobenzotriazole silver, 5-methoxybenzotriazole silver, 4-sulfobenzotriazole silver, 4-hydroxybenzotriazole silver, 5-aminobenzotriazole silver, 5-carboxybenzotoazole 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, saccharin silver, phthalazinone silver, phthalimide silver, and others 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-1,2,3,4, 6-Pentazaindene silver and the like. Among the above organic silver salts, silver salts of imino groups are preferable, particularly silver salts of benzotriazole derivatives, more preferably silver salts of sulfobenzotriazole derivatives.

The organic silver salt used in the present invention may be used alone or in combination of two or more kinds, and the isolated silver salt may be dispersed in a binder by a suitable means before use. The silver salt may be prepared in a binder and used as it is without isolation.

The amount of the organic silver salt used is 1 mol of photosensitive silver halide.
It is preferably 0.01 to 500 mol, more preferably
It is 0.1 mol to 100 mol.

The reducing agent used in the photothermographic material of the present invention, it is possible to use those usually used in the field of photothermographic material, for example, U.S. Patent No. 3,531,286, the same 3,761,270,
Nos. 3,764,328 specifications, RD No. 12146, No. 15
108, No. 15127 and JP-A-56-27132, and the like, p-phenylenediamine-based and p-aminophenol-based developing agents, phosphoroamidophenol-based and sulfonamidephenol-based developing agents, or hydrazone-based color developing agents. Examples include developing agents. Also, U.S. Pat.
2,599, 3,719,492, JP-A-53-135628, 54
Color developing agent precursors described in -79035 and the like can also be advantageously used.

Particularly preferred reducing agents include reducing agents represented by the following general formula (1) described in JP-A-56-146133.

General formula (1) In the formula, R ¹ and R ² represent a hydrogen atom or an optionally substituted alkyl group having 1 to 30 carbon atoms (preferably 1 to 4), and R ¹ and R ² are ring-closed. A heterocycle may be formed. R ³ , R ⁴ R ⁵ and R ⁶ are a hydrogen atom, a halogen atom, a hydroxy group, an amino group, an alkoxy group, an acylamido group,
Sulfonamide group, alkylsulfonamide group or C1 to C30 which may have a substituent (preferably 1 to 30)
4) represents an alkyl group, and R ³ and R ¹ and R ⁵ and R ² may 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 element.

The nitrogen-containing organic base in the above general formula (1) is an organic compound containing a nitrogen atom having basicity capable of forming a salt with an inorganic acid, and particularly important organic bases include amine compounds. Primary amines, secondary amines, tertiary amines, and the like are used as chain amine compounds, and pyridine, quinoline, and piperidine, which are prominent examples of typical heterocyclic organic bases, are used as cyclic amine compounds. , Imidazole and the like. In addition, compounds such as hydroxylamine, hydrazine and amidine are also useful as chain amines. As the salt of the nitrogen-containing organic base, the inorganic acid salt of the above-mentioned organic base (for example, hydrochloride, sulfate, nitrate, etc.) is preferably used.

On the other hand, examples of the compound containing quaternary nitrogen in the above general formula include salts and hydroxides of nitrogen compounds having a tetravalent covalent bond.

Next, preferable specific examples of the reducing agent represented by the general formula (1) are shown below.

The reducing agent represented by the general formula (1) can be obtained by a known method,
For example, Hoyben Bale, Mesodden del Organischen Chemie, band XI / 2 (Houben-Weyl, Methode
Nerder Organischen Chemie, Band XI / 2) 645-703.

On the other hand, dye-donor substances are disclosed in JP-A Nos. 57-179840 and 58-58.
No. 543, No. 59-152440, No. 59-154445, a compound that releases a dye by oxidation, a compound that loses its dye releasing ability by oxidation, a compound that releases a dye by reduction, or a dye-donating agent. When only a silver image is obtained without containing a substance, a reducing agent as described below can be used.

For example, phenols (for example, p-phenylphenol, p-methoxyphenol, 2,6-di-tert-butyl-p-cresol, N-methyl-p-aminophenol, etc.), sulfonamidephenols [for example, 4-benzene Sulfonamidophenol, 2-benzenesulfonamidophenol, 2,6-dichloro-4-benzenesulfonamidophenol, 2,6-dibromo-4- (p-toluenesulfonamido) phenol, etc.], or polyhydroxybenzenes (for example, Hydroquinone, tert-butylhydroquinone, 2,6-dimethylhydroquinone, chlorohydroquinone, carboxyhydroquinone, catechol, 3-carboxycatechol, etc., naphthols (eg, α-naphthol, β-naphthol, 4-aminonaphthol, 4-methoxynaphtho). Le etc.), hydroxy binaphthyls and methylene bis naphthols [e.g.
1,1'-dihydroxy-2,2'-binaphthyl, 6,6'-dibromo-2,2'-dihydroxy-1,1'-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 [eg 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-dimethylphenyl) propane, 2,2-bis (4-hydroxy-3-methyl-5-ter
t-butylphenyl) propane, 2,2-bis (4-hydroxy-3,5-di-tert-butylphenyl) propane, etc.], ascorbic acids, 3-pyrazolidones, pyrazolones, hydrazones and paraphenylenediamines Is mentioned.

These reducing agents may be used alone or in combination of two or more. The amount of the reducing agent used depends on the type of the photosensitive silver halide used, the type of the organic acid silver salt and the type of other additives, but is usually 0.01 per 1 mol of the photosensitive silver halide. The range is ˜1500 mol, preferably 0.1-200 mol.

Examples of the binder used in the photothermographic material of the present invention include polyvinyl butyral, polyvinyl acetate, ethyl cellulose, polymethyl methacrylate, cellulose acetate butyrate, polyvinyl alcohol, polyvinyl pyrrolidone, gelatin and phthalated gelatin. One or a combination of two or more molecular substances can be used. In particular, it is preferable to use gelatin or a derivative thereof in combination with a silver aqueous polymer such as polyvinylpyrrolidone or polyvinyl alcohol, and more preferably the following binders described in Japanese Patent Application No. 58-104249.

This binder contains gelatin and a vinylpyrrolidone polymer. The vinylpyrrolidone polymer may be polyvinylpyrrolidone which is a homopolymer of vinylpyrrolidone, or a copolymer (including a graft copolymer) with one or more other monomers copolymerizable with vinylpyrrolidone. ) May be sufficient. These polymers can be used regardless of their degree of polymerization. The polyvinylpyrrolidone may be a substituted polyvinylpyrrolidone, preferred polyvinylpyrrolidone having a molecular weight of 1,000 to 400,000. Other monomers copolymerizable with vinylpyrrolidone include (meth) acrylic acid esters such as acrylic acid, methacrylic acid and alkyl esters thereof, vinyl alcohols, vinylimidazoles, (meth) acrylamides, vinylcarbinols. , Vinyl-based monomers such as vinyl alkyl ethers, etc.,
It is preferable that at least 20% (% by weight, hereinafter the same) of the composition ratio is polyvinylpyrrolidone. Preferred examples of such copolymers have a molecular weight of 5,000 to 400,000.

The gelatin may be lime-treated or acid-treated, and may be ossein gelatin, pigskin gelatin, hide gelatin or modified gelatin obtained by esterification or phenylcarbamoylation thereof.

In the above binder, gelatin is preferably 10 to 90% of the total amount of binder, more preferably 20
It is preferably -60%, vinylpyrrolidone is 5-90%, and more preferably 10-80%.

The binder may contain other polymeric substances,
Mixture of gelatin and polyvinylpyrrolidone having a molecular weight of 1,000 to 400,000 with one or more other polymeric substances, and mixture of gelatin and vinylpyrrolidone copolymer having a molecular weight of 5,000 to 400,000 with one or more other polymeric substances. Is preferred. Other polymer substances used include polyvinyl alcohol, polyacrylamide, polymethacrylamide, polyvinyl butyral, polyethylene glycol,
Examples thereof include proteins such as polyethylene glycol ester and cellulose derivatives, and natural substances such as polysaccharides such as starch and gum arabic. These are 0-85
%, Preferably 0-70%.

The vinylpyrrolidone polymer may be a crosslinked polymer, but in this case, it is preferable that the vinylpyrrolidone polymer is coated on the support and then crosslinked (including the case where the crosslinking reaction is allowed to stand by itself).

The amount of binder used is usually 0.05 g per 1 m ² per layer.
~ 50g, preferably 0.1g ~ 10g.

The support used in the photothermographic material of the present invention includes
For example, a polyethylene film, a cellulose acetate film and a polyethylene terephthalate film, a synthetic plastic film such as polyvinyl chloride, and a paper support such as photographic base paper, printing paper, baryta paper and resin coated paper, and a reflective layer on the above synthetic plastic film. And a support provided with.

Various additives may be added to the photothermographic material of the present invention, if necessary, in addition to the above components. For example, as a development accelerator, U.S. Patent Nos. 3,220,840 and 3,531,285
No. 4,012,260, No. 4,060,420, No. 4,088,49
No. 6, No. 4,207,392 each specification, RD No. 15733, No. 157
34, ibid. No. 15776, JP-A-56-130745, JP-A-56-132332, etc., alkali releasing agents such as urea and guanidinium trichloroacetate, organic acids described in JP-B-45-12700, US described in Japanese Patent No. _{3,667,959 -CO -, - SO 2 -} , -
Non-aqueous polar solvates with SO-groups, U.S. Pat.
Melt former described in US Pat. No. 3,666,477
And polyalkylene glycols described in JP-A-51-19525. Further, as a color tone agent, for example, JP-A-46
-4928, 46-6077, 49-5019, 49-5020
No. 49-91215, No. 49-107727, No. 50-2524,
50-67132, 50-67641, 50-114217, 52
-33722, 52-99813, 53-1020, 53-5511
No. 5, No. 53-76020, No. 53-125014, No. 54-156523
No. 54, No. 54-156524, No. 54-156525, No. 54-156526
No. 55-4060, No. 55-4061, No. 55-32015 and West German Patent No. 2,140,406, No. 2,147,063
No. 2,220,618, U.S. Pat.No. 3,080,254, No. 3,
No. 847,612, No. 3,782,941, No. 3,994,732, No. 3
Phthalazinone, phthalimide, pyrazolone, quinazolinone, N-hydroxynaphthalimide, benzoxazine, naphthoxazinedione, which are compounds described in each specification such as 4,123,282 and 4,201,582.
-Dihydro-phthalazinedione, 2,3-dihydro-1,3-
Oxazine-2,4-dione, oxypyridine, aminopyridine, hydroxyquinoline, aminoquinoline, isocarbostyril, sulfonamide, 2H-1,3-benzothiazine-2,4- (3H) dione, benzotriazine, mercaptotriazole, Dimercaptotetrasapentalene,
Phthalic acid, naphthalic acid, phthalamic acid, etc., and a mixture of one or more of these with an imidazole compound, or a mixture of at least one acid or acid anhydride such as phthalic acid, naphthalic acid and a phthalazine compound, Furthermore, a combination of phthalazine and maleic acid, itaconic acid, quinolinic acid, gentisic acid and the like can be mentioned. Further, 3-amino-5-mercapto-1,2,4-triazoles, 3-acylamino-5-mercapto-1, described in JP-A Nos. 58-189628 and 58-193460 are disclosed.
2,4-triazoles are also effective.

Further, as the antifoggant, for example, Japanese Patent Publication No.
-11113, JP-A-49-90118, 49-10724, 49
-97613, 50-101019, 49-130720, 50-1
No. 23331, No. 51-47419, No. 51-57435, No. 51-78227
No. 51-104338, No. 53-19825, No. 53-20923,
51-50725, 51-3223, 51-42529, 51-
81124, 54-51821, 55-93149, etc., as well as British Patent No. 1,455,271 and U.S. Patent No. 3,885,968.
No. 3,700,457, 4,137,079, 4,138,26
No. 5, West German Patent No. 2,617,907 and the like, which are the compounds described in each specification, such as a mercuric salt, or an oxidizing agent (for example,
N-halogenoacetamide, N-halogenosuccinimide, perchloric acid and its salts, inorganic peroxides, persulfates, etc., or acid and its salts (for example, sulfinic acid, lithium laurate, rosin, diterpenic acid) , Thiosulfonic acid, etc.), or sulfur-containing compounds (eg, mercapto compound-releasing compounds, thiouracil, disulfide, sulfur simple substance, mercapto-1,2,4-triazole, thiozoline thione, polysulfide compounds, etc.), other, oxazoline, 1,2 Examples thereof include compounds such as 4,4-triazole and phthalimide. Further, a thiol (preferably thiophenol compound) compound described in JP-A-59-111636 is also effective as another antifoggant.

Other antifoggants include hydroquinone derivatives described in Japanese Patent Application No. 59-56506 (for example, di-t-octylhydroquinone, dodecanylhydroquinone, etc.) and hydroquinone derivatives described in Japanese Patent Application No. 59-66380. And a benzotriazole derivative (for example, 4-sulfobenzotriazole, 5-carboxybenzotriazole, etc.) can be preferably used in combination.

Further, as a stabilizer, a print-out preventing agent may be used at the same time after the treatment, for example, JP-A-48-45228 and JP-A-48228 / 1993.
No. 119624, No. 50-120328, No. 53-46020 and the like halogenated hydrocarbons, specifically tetrabromobutane, tribromoethanol, 2-bromo-2-tolylacetamide, 2-bromo 2-trisulfonylacetamide, 2-tribromomethylsulfonylbenzothiazole, 2,4-bis (tribromomethyl) -6-methyltriazine and the like can be mentioned.

Also, Japanese Patent Publication No. 46-5393, Japanese Patent Laid-Open Nos. 50-54329, 50-770.
Post-treatment may be carried out using a sulfur-containing compound as described in JP-A No. 34-34.

Furthermore, U.S. Pat.Nos. 3,301,678 and 3,506,444,
No. 3,824,103, No. 3,844,788 isothiuronium-based stabilizer precursor described in each specification, also U.S. Patent No. 3,669,670, No. 4,012,260, No. 4,060,42
The activator stabilizer precursor described in the specification No. 0 and the like may be contained.

Further, a water releasing agent such as sucrose or NH ₄ Fe (SO ₄ ) ₂ · 12H ₂ O may be used. Furthermore, as in JP-A-56-132332, water is supplied to carry out heat development. Good.

In addition to the above components, the photothermographic material of the present invention may further contain various additives such as antihalation dyes, optical brighteners, hardeners, antistatic agents, plasticizers, spreading agents, and coating aids, if necessary. Agents and the like can be added.

When the photothermographic material of the invention is of the color type, a dye-donor substance is used.

Hereinafter, the dye-providing substance that can be used in the present invention will be described. The dye-donating substance may be any one as long as it can participate in the reduction reaction of the photosensitive silver halide and / or the organic silver salt optionally used and can form or release a diffusible dye as a function of the reaction, Depending on the reaction form, a negative-working dye-donor that acts on a positive function (that is, it forms a negative dye image when using a negative-working silver halide) and a positive-working that works on a negative function. Dye-donor substances (ie, a positive dye image is formed when a negative-working silver halide is used). Negative type dye-donor substances are further classified as follows.

Each dye-donor will be further described.

Examples of the reducing dye releasing compound include compounds represented by the general formula (2).

General formula (2) Car-NHSO ₂ -Dye In the formula, Car is a reducing substrate (so-called carrier) that is oxidized to release a dye upon reduction of the photosensitive silver halide and / or the organic silver salt used as necessary. ), And Dye is a diffusible dye residue.

Specific examples of the above reducing dye-releasing compound include those disclosed in JP-A-
57-179840, 58-116537, 59-60434, 59
-65839, 59-71046, 59-87450, 59-887
No. 30, 59-123837, 59-165054, 59-165055
The following compounds are mentioned, for example.

Exemplified dye donor As another reducing dye-releasing compound, for example, general formula (3)
The compound shown by is mentioned.

General formula (3) In the formula, A ₁ and A ₂ each represent a hydrogen atom, a hydroxy group or an amino group, and Dye has the same meaning as Dye represented by the general formula (2). Specific examples of the above compounds are shown in JP-A-59-124329.

As the coupling dye-releasing compound, a compound represented by the general formula (4)
The compound shown by is mentioned.

General formula (4) Cp ₁ Jn ₁ Dye In the formula, Cp ₁ is an organic group capable of reacting with an oxidant of a reducing agent to release a diffusible dye (so-called coupler residue).
And J is a divalent linking group, and the bond between Cp ₁ and J is cleaved by the reaction with the oxidized form of the reducing agent. n ₁ is 0 or 1
And Dye has the same meaning as defined by the general formula (2). Further, Cp ₁ is preferably substituted with various ballast groups in order to make the coupling dye-releasing compound non-diffusible. The ballast group has 8 or more carbon atoms depending on the form of the photosensitive material used. (More preferably 12
Or more) organic groups, or hydrophilic groups such as sulfo groups and carboxy groups, or groups having both 8 or more (more preferably 12 or more) carbon atoms and hydrophilic groups such as sulfo groups and carboxy groups. is there. Another particularly preferred ballast group may include a polymer chain.

Specific examples of the compound represented by the above general formula (4) include JP-A Nos. 57-186744, 57-122596, and 57-1606.
98, 59-174834, 57-224883, 59-159159
And Japanese Patent Application No. 59-104901, and examples thereof include the following compounds.

Exemplified dye donor Examples of the coupling dye-forming compound include those represented by the general formula (5)
The compound shown by is mentioned.

In the general formula (5) Cp ₂ FB), Cp ₂ is an organic group (so-called coupler residue) capable of forming a diffusible dye by reacting with an oxidant of a reducing agent (coupling reaction), F represents a divalent linking group, and B represents a ballast group.

The coupler residue represented by Cp ₂ has a molecular weight of preferably 700 or less, more preferably 500 or less because of the diffusibility of the dye formed.

Further, the ballast group is preferably the same ballast group as the ballast group defined by the general formula (4), particularly 8 or more (more preferably 12 or more) carbon atoms and a hydrophilic group such as a sulfo group or a carboxy group. A group having both groups is preferable, and a polymer chain is more preferable.

As the coupling dye-forming compound having the polymer chain, a polymer having a repeating unit derived from the monomer represented by the general formula (6) is preferable.

General formula (6) Cp ₂ FYlZL) In the formula, Cp ₂ and F have the same meanings as defined in the general formula (5), Y represents an alkylene group, an aryler group or an aralkylene group, and l represents 0 or 1 , Z represents a divalent organic group, and L represents an ethylenically unsaturated group or a group having an ethylenically unsaturated group.

Specific examples of the coupling dye-forming compound represented by the general formulas (5) and (6) include JP-A-59-124339,
59-181345, Japanese Patent Application No. 58-109293, 59-179657.
No. 59-181604, No. 59-182506, No. 59-182507 and the like, and examples thereof include the following compounds.

Exemplified dye donor polymer In the above general formulas (4), (5) and (6), Cp ₁
Further, the coupler residue defined by Cp ₂ will be described in more detail, and a group represented by the following general formula is preferred.

In the formula, R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an aryl group,
Acyl group, alkyloxycarbonyl group, aryloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group, carbamoyl group, sulfamoyl group, acyloxy group, amino group, alkoxy group, aryloxy group, cyano group, ureido group, alkylthio group, arylthio Represents a group, a carboxy group, a sulfo group or a heterocyclic residue, and these further include a hydroxyl group, a carboxy group, a sulfo group,
It may be substituted with an alkoxy group, a cyano group, a nitro group, an alkyl group, an aryl group, an aryloxy group, an acyloxy group, an acyl group, a sulfamoyl group, a carbamoyl group, an imide group, a halogen atom or the like.

These substituents are selected according to the purpose of Cp ₁ and Cp ₂ ,
As described above, in Cp ₁ , _one of the substituents is preferably a ballast group, and in Cp ₂ , it is substituted so that the molecular weight is 700 or less, more preferably 500 or less in order to enhance the diffusibility of the dye formed. It is preferred that a group is selected.

As the positive type dye-donating substance, for example, the following general formula (1
There are oxidizing dye-releasing compounds represented by 7).

General formula (17) In the formula, W ₁ represents a group of atoms necessary for forming a quinone ring (which may have a substituent on this ring), and R 1
¹¹ represents an alkyl group or a hydrogen atom, and E is (In the formula, R ¹² represents an alkyl group or a hydrogen atom, and R ¹³ represents an oxygen atom or Represents ) Or —SO ₂ —, r represents 0 or 1, and Dye has the same meaning as defined in formula (2). Specific examples of this compound are disclosed in JP-A-59-166954 and JP-A-59-166954.
No. 154445 and the like, and examples thereof include the following compounds.

Exemplified dye donor Another positive dye-donor substance is a compound represented by the following general formula (18), which loses its dye releasing ability when oxidized.

General formula (18) In the formula, W ₂ represents a group of atoms necessary for forming a benzene ring (which may have a substituent on the ring),
R ¹¹ , r, E and Dye are defined as those defined by the general formula (17). Specific examples of this compound are JP-A-59-124329,
No. 59-154445 and the like, and examples thereof include the following compounds.

Exemplified dye-providing substance Still another positive type dye-donor substance includes compounds represented by the following general formula (19).

General formula (19) In the above formula, W ₂ , R ¹¹ and Dye have the same meaning as defined in the general formula (18). Specific examples of this compound are described in JP-A-59-154445 and the like, for example, the following compounds.

Exemplified dye donor The residue of the diffusible dye represented by Dye in the above general formulas (2), (3), (4), (17), (18) and (19) will be described in more detail. The residue of the diffusible dye has a molecular weight of 800 or less, more preferably 600 because of the diffusibility of the dye.
The following are preferred, and examples thereof include residues of azo dyes, azomethine dyes, anthraquinone dyes, naphthoquinone dyes, styryl dyes, nitro dyes, quinoline dyes, carbonyl dyes, phthalocyanine dyes and the like. These dye residues may be in the form of a temporary short-wave that allows multiple colors during heat development or transfer. Further, these dye residues are used for the purpose of improving the light fastness of the image, for example, JP-A-59-48765 and 59-59.
The chelatable dye residue described in -124337 is also a preferred form.

These dye-donor substances may be used alone or in combination of two or more. The amount used is not limited, depending on the type of the dye-donating substance, a single use or a combination use of two or more kinds, or whether the photographic constituent layers of the light-sensitive material of the present invention are a single layer or two or more layers. The amount may be 0.005 g to 50 g, and preferably 0.1 g to 10 g per 1 m ² , though it may be determined depending on the case.

The method for incorporating the dye-donor substance used in the present invention into the photographic constituent layer of the photothermographic material is arbitrary and includes, for example, a low-boiling point solvent (methanol, ethanol, ethyl acetate, etc.) or a high-boiling point solvent (dibutyl phthalate, dioctyl phthalate, tritium). Cresyl phosphate, etc.) and then ultrasonically dispersed or dissolved in an alkaline aqueous solution (eg, 10% sodium hydroxide solution), and then neutralized with a mineral acid (eg, hydrochloric acid or nitric acid). It can be used after being used or after being dispersed with a suitable polymer aqueous solution (eg, gelatin, polyvinyl butyral, polyvinyl pyrrolidone, etc.) using a ball mill.

Various exposing means can be used for the photothermographic material of the present invention. The latent image is obtained by imagewise exposure to radiation containing visible light. Generally, a light source used for ordinary color printing, for example, a tungsten lamp, a mercury lamp, a xenon lamp, a laser beam, a CRT beam or the like can be used as the light source.

As the heating means, all methods applicable to ordinary photothermographic materials can be used, for example, contact with a heated block or plate, contact with a heat roller or a heat drum, or passage through a high temperature atmosphere. Alternatively, high frequency heating may be used, or a Joule heat generated by energization or a strong magnetic field may be used by providing a conductive layer in the light-sensitive material of the present invention or the image receiving member for thermal transfer. The heating pattern is not particularly limited, including a method of preheating (preheating) in advance and then heating again,
High temperature for a short time or low temperature for a long time continuously rising,
Although it can be lowered or repeated, and discontinuous heating is possible, a simple pattern is preferable. Further, it may be a system in which exposure and heating proceed simultaneously.

When the photothermographic material of the present invention is of a black and white type which forms a silver image, it is usually 80 ° C to
Development is carried out by heating in the temperature range of 250 ° C., preferably 100 ° C. to 200 ° C., for 1 second to 240 seconds, preferably 1.5 seconds to 120 seconds. In addition, preheating may be performed in the temperature range of 70 ° C to 200 ° C before exposure.

The photothermographic material on which a silver image is formed can be displayed and stored as it is, but when storage for a longer period is required, unreacted silver salt is preferably removed.

The unreacted silver salt is removed by a bleaching bath, a fixing bath or a bleach-fixing bath used in a usual wet photographic method (see, for example, JP-A-
-54329, 50-77034, 51-328, 51-80226
No. 59-136733,
Retarch Disclosure No. 16407, Same No. 16408, Same
A bleach-fixing sheet as described in No. 16414 can also be used.

Further, when the photothermographic material which is a preferred embodiment of the present invention is a color type using a dye-donor substance, the image receiving member described later and the exposed photosensitive layer side of the photothermographic material of the present invention have a stacking relationship. And is usually transferred to the image receiving member at the same time as color development by heating in the temperature range of 80 ° C. to 200 ° C., preferably 120 ° C. to 170 ° C. for 1 second to 180 seconds, preferably 1.5 seconds to 120 seconds. . In addition, 70 ° C before exposure
Preheating may be performed in a temperature range of to 180 ° C.

The image-receiving member used in the present invention may have a function of receiving a dye released or formed by thermal development, and may be a mordant used in a dye diffusion transfer type light-sensitive material or JP-A-57-2072.
Glass transition temperature described in No. 50 is 40 ℃ or more, 250 ℃
It is preferably formed of the following heat-resistant organic polymer substances.

Specific examples of the mordant, nitrogen-containing secondary, tertiary amines, nitrogen-containing heterocyclic compounds, these quaternary cationic compounds, U.S. Patent Nos. 2,548,564, 2,484,430, 3,4,
Vinyl pyridine polymers and vinyl pyridinium cation polymers disclosed in 148,061 and 3,756,814, polymers containing dialkylamino groups disclosed in U.S. Pat.No. 2,675,316, aminoguanidine derivatives disclosed in U.S. Pat. , JP-A-54-13
Covalently bonded reactive polymers described in 7333, U.S. Pat.Nos. 3,625,694, 3,859,096, and British Patent 1,277,453.
Nos. 2,011,012 and mordants capable of crosslinking with gelatin and the like, U.S. Patent Nos. 3,958,995 and 2,721,852
No. 2,798,063 aqueous sol type mordant disclosed in JP-A-50-61228, U.S. Pat.No. 3,788,855, West German patent application (OLS) No. 2,
843,320, JP-A-53-30328, 52-155528, 53
-125, 53-1024, 54-74430, 54-124726
No. 55-22766, U.S. Pat.Nos. 3,642,482, 3,488,
No. 706, No. 3,557,066, No. 3,271,147, No. 3,271,148
No. 5, Japanese Patent Publication No. 55-29418, No. 56,36414, No. 57-12139
And various mordanting agents disclosed in RD12045 (1974).

Particularly useful mordants are polymers containing ammonium salts,
It is a polymer containing a quaternary amino group described in US Pat. No. 3,709,690. Examples of the polymer containing an ammonium salt include polystyrene-co-N, N, N-tri-n-hexyl-N-vinylbenzylammonium chloride,
The ratio of styrene to vinylbenzylammonium chloride is 1: 4 to 4: 1, preferably 1: 1.

A typical image receiving layer for dye diffusion transfer is obtained by mixing a polymer containing an ammonium salt with gelatin and coating the mixture on a support.

An example of the heat-resistant organic polymer substance has a molecular weight of 2,000.
~ 85,000 polystyrene, polystyrene derivatives having substituents of 4 or less carbon atoms, polyvinyl cyclohexane, polyvinyl benzene, polyvinyl pyrrolidone, polyvinyl carbazole, polyallyl benzene, polyvinyl alcohol, polyvinyl formal and polyvinyl butyral, and other polyacetals, polyvinyl chloride , Chlorinated polyethylene, polytrifluoroethylene, polyacrylonitrile, poly-N, N-dimethylacrylamide, p-cyanophenyl group, pentachlorophenyl group and 2,4-
Polyacrylate with dichlorophenyl group, polyacrylchloroacrylate, polymethylmethacrylate,
Polyethylmethacrylate, polypropylmethacrylate, polyisopropylmethacrylate, polyisobutylmethacrylate, poly-tert-butylmethacrylate,
Examples thereof include polyesters such as polycyclohexyl methacrylate, polyethylene glycol dimethacrylate, poly-2-cyano-ethyl methacrylate and polyethylene terephthalate, polysulfones, polycarbonates such as bisphenol A polycarbonate, polyanhydrides, polyamides and cellulose acetates. In addition, the Polymer Handbook Second Edition (Poly
mer Handbook 2nd ed.), J Brand Wrap, H. Inmargut (J. Brandrup, E.
H. Immergut), glass transition temperature as described by John Wiley & Sons.
Synthetic polymers above 40 ° C are also useful. These polymer substances may be used alone or in combination of two or more and used as a copolymer.

Particularly useful polymers include cellulose acetates such as triacetate and diacetate, heptamethylenediamine and terephthalic acid, fluorenedipropylpropylamine and adipic acid, hexamethylenediamine and diphenic acid, and polyamides in combination with hexamethylenediamine and isophthalic acid. Polyester by a combination of diethylene glycol and diphenylcarboxylic acid, bis-p-carboxyphenoxybutane and ethylene glycol,
Examples thereof include polyethylene terephthalate, polycarbonate and vinyl chloride. These polymers may be modified. For example, polyethylene terephthalate using cyclohexanedimethanol, isophthalic acid, methoxypolyethylene glycol, 1,2-dicarbomethoxy-4-benzenesulfonic acid or the like as a modifier is also effective. Of these, Japanese Patent Application No. Sho 58 is particularly preferable.
Examples of the layer include a polyvinyl chloride layer described in JP-A-97907 and a layer formed of a polycarbonate and a plasticizer described in Japanese Patent Application No. 58-128600.

The above-mentioned polymer is dissolved in a suitable solvent and applied on a support to form an image-receiving layer, or a film-like image-receiving layer comprising the above-mentioned polymer is laminated on the support and used, or applied on the support. Alternatively, the member (for example, a film) made of the above polymer may be used alone to form the image receiving layer (also used as the image receiving layer support).

Further, the image receiving layer may be formed by providing an opaque layer (reflective layer) containing titanium dioxide dispersed in gelatin on the image receiving layer on a transparent support. With this opaque layer, a reflective color image can be obtained by viewing the transferred color image from the transparent support side of the image receiving layer.

Specific Examples of the Invention Hereinafter, the present invention will be specifically described with reference to Examples, but the embodiments of the present invention are not limited thereto.

Example 1 [Preparation of silver bromide emulsion] A comparative silver bromide emulsion A was prepared by the following method. 50
At 0 ° C., using a mixing stirrer described in the specifications of JP-A Nos. 57-92523 and 57-92524, ossein gelatin 20
g, 100 ml of distilled water and 500 ml of an aqueous solution containing 1.1 mol of potassium bromide in a solution of dissolved (A) and 500 ml of an aqueous solution containing 1 mol of silver nitrate and ammonia (C) The solution was added at the same time while keeping the pAg constant. The shape and size of the prepared emulsion grains were adjusted by controlling the pH, pAg, and the addition rate of solutions (B) and (C). Thus, a silver bromide emulsion was prepared.

The obtained silver halide grains were octahedral grains with an average grain size of 0.3 μm and a monodispersity of 8%.

This emulsion was washed with water and desalted. The emulsion yield was 800 ml.

[Preparation of silver iodobromide emulsion] Silver halide emulsions B, C and D containing three types of photosensitive silver halides having different silver iodide contents were prepared by the following method.

At 50 ° C., ossein gelatin 20 using a mixing stirrer described in JP-A Nos. 57-92523 and 57-92524.
g, 100 ml of distilled water and a solution (A) in which ammonia was dissolved, and potassium iodide and potassium bromide were given predetermined concentrations (for emulsion B, 4,98 g of potassium iodide, 131 g of potassium bromide, and for emulsion C, potassium iodide). 6.64 g, potassium bromide 131 g, for emulsion D, potassium iodide 11.62 g, potassium bromide 131 g) 500 ml of an aqueous solution (B) solution and 1 ml of silver nitrate and 500 ml of an aqueous solution containing ammonia ( Solution C) was added at the same time while keeping the pAg constant. The shape and size of the prepared emulsion grains were adjusted by controlling the pH, pAg, and the addition rate of solutions (B) and (C). In this way, emulsions having the same regular octahedron shape but different silver iodide contents were prepared. (The monodispersity of each emulsion was 9%.) These emulsions were washed with water and desalted. The yield of each emulsion was 800 ml.

The average grain size and silver iodide content of each of the comparative silver halide emulsions A to D thus prepared are shown in Table 1 below.

Table-1 Emulsion average particle size Silver iodide content A (comparison) 0.3 μm 0 B (comparison) 0.3 μm 3 mol% C (invention) 0.3 μm 4 mol% D (invention) 0.3 μm 7 mol % [Preparation of core / shell type silver iodobromide emulsion] Three kinds of core / shell type emulsions E, F and G having different silver iodide contents and average grain sizes were prepared by the following method.

At 50 ° C., ossein gelatin 20 using a mixing stirrer described in JP-A Nos. 57-92523 and 57-92524.
g, 1000 ml of distilled water and a solution (A) in which ammonia was dissolved, and potassium iodide and potassium bromide were given predetermined concentrations (for emulsion E, potassium iodide 11.62 g, potassium bromide 131 g, emulsion F for potassium F 11.62). g, potassium bromide 131 g, and for emulsion G, potassium iodide 33.2 g, potassium bromide 119 g) in an aqueous solution of 500 ml (B) and an aqueous solution containing 1 mol of silver nitrate and ammonia (C) (C). ) Liquid and pAg at the same time
Was kept constant and added. The shape and size of the particles of the prepared core emulsion were prepared by controlling the pH, pAg and the addition rate of the (B) solution and the (C) solution. In this way positive 8
Core emulsions having the same shape of face and different average grain size and silver iodide content were prepared. (The monodispersity of each emulsion is 8%
Then, using the obtained silver halide grain as a core, the same procedure as described above was applied to the same (however, the respective potassium iodide concentrations and potassium bromide concentrations of the solution (B) for shell were different for emulsion E). By coating 3.32 g of potassium iodide, 131 g of potassium bromide, 3.32 g of potassium iodide and 131 g of potassium bromide for emulsion F, and 3.32 g of potassium iodide and 131 g of potassium bromide for emulsion G,
Core / shell type silver halide emulsions having the same shape of a regular octahedron but different in average grain size and silver iodide content were prepared.

Each of these emulsions was washed with water and desalted. The yield of each emulsion was 800 ml.

The average grain size and the silver iodide content of each of the core / shell type silver halide emulsions E to G thus prepared are shown in Table 2 below.

[Preparation of Organic Silver Salt Dispersion-1] 2-Methylbenzotriazole silver (28.8 g) obtained by reacting 5-methylbenzotriazole and silver nitrate in a water-alcohol mixed solvent and poly (N-vinylpyrrolidone) 16.
0 g and 4-sulfobenzotriazole sodium salt 1.
Disperse 33 g with alumina ball mill, adjust to pH 5.5 and 200 ml
And

[Preparation of Photosensitive Silver Halide Dispersion] The silver halide emulsion No. D prepared above was used as a compound of the present invention [sensitizing dye (I) and sensitizing dye (II)] in the following Table-3.
And the combination of 4-hydroxy-6-methyl-
Sulfur sensitization treatment with sodium thiosulfate was carried out in the presence of 1,3,3a, 7-tetrazaindene to prepare a photosensitive silver halide emulsion dispersion having the following composition.

Photosensitive silver halide (converted to silver) 381 g Gelatin 85/2820 ml [Preparation of Dye-donor substance dispersion liquid-1] 35.5 g of the exemplified dye-donor substance and 5.00 g of the following hydroquinone compound are dissolved in 200 ml of ethyl acetate to prepare an alkanol.
XC (DuPont) 5% by weight aqueous solution 124 ml Phenylcarbamoylated gelatin (Ruslaw, type 17819PC) 30.
The mixture was mixed with 720 ml of a gelatin aqueous solution containing 5 g and dispersed with an ultrasonic homogenizer, and ethyl acetate was distilled off to adjust the pH to 5.5 to 795 ml.

Hydroquinone compound [Preparation of reducing agent dispersion liquid-1] 23.3 g of the exemplary reducing agent (R-11), 1.10 g of the following development accelerator, 14.6 g of poly (N-vinylpyrrolidone), and 0.50 g of the following fluorochemical surfactant are dissolved in water. Then, the pH was adjusted to 5.5 to 250 ml.

Development accelerator Surfactant [Preparation of Photothermographic Material-1] 12.5 ml of the organic silver salt dispersion liquid-1 prepared above, 6.00 ml of the silver halide dispersion liquid, 39.8 of the dye-donor dispersion liquid-1.
ml, and 12.5 ml of reducing agent dispersion-1 are mixed, and further, a hardener solvent {tetra (vinylsulfonylmethyl) methane and taurine are reacted at a ratio of 1: 1 (weight ratio) to prepare a 1% phenylcarbamoylated gelatin aqueous solution. Dissolved in to make tetra (vinylsulfonylmethyl) methane 3% by weight. } 2.50 ml of polyethylene glycol and 300 g of polyethylene glycol 300 (manufactured by Kanto Kagaku Co., Ltd.) as a heat solvent, and then 1.76 g / m ^{2 of} silver on a 180 μm thick polyethylene terephthalate film for underphotography. So that
Further thereon, a protective layer made of a mixture of the phenylcarbamoylated gelatin and poly (N-vinylpyrrolidone) was provided.

[Preparation of Image Receiving Member-1] Polyvinyl chloride (n = 1,100,
A tetrahydrofuran solution of Wako Pure Chemical Industries, Ltd.) was applied so that the polyvinyl chloride would be 12 g / m ² .

Through the step wedge for the photothermographic material
The exposure of 1,600 CMS was applied and combined with the image receiving member, it was 150 in a thermal processor (Developer Module 277, 3M Company).
After heat development at 1 ° C. for 1 minute, the photothermographic material and the image receiving member were quickly peeled off, and a magenta colored step wedge screw image was obtained on the image receiving member and the polyvinyl chloride surface.

On the other hand, the same exposed light-sensitive material was developed with a developer having the following composition at 20 ° C. for 3 minutes, stopped, fixed, washed with water and dried to obtain a black and white image.

Table 3 shows the sensitivity of the black-and-white image and the sensitivity of the magenta transfer image obtained by heat development as relative values. Comparative sample No. 9
The sensitivity of the black and white image of was set to 100, and the sensitivity was determined by the point of fog +0.2.

[Developer composition] Metol 2 g Anhydrous sodium sulfite 40 g Hydroquinone 4 g Sodium carbonate monohydrate 28 g Potassium bromide 1 g Water is added to make 1.

As is clear from Table 3, only the sensitizing dye (I) or the sensitizing dye (II) of the compounds of the present invention was used in the silver halide emulsion containing the photosensitive silver halide grains of the present invention. Compared with the comparative samples (Nos. 9 to 12), the samples (No. 1 to 8) in which the sensitizing dye (I) and the sensitizing dye (II) of the compound of the present invention were used in combination were subjected to heat development. The desensitization is small, and the sensitizing effect on the photosensitive silver halide is also good, which shows that the photothermographic material has high sensitivity.

Example 2 In Example 1, the silver halide emulsions shown in Table 4 below and the compounds of the present invention [sensitizing dye (I) and sensitizing dye (I
A photosensitive silver halide dispersion liquid was prepared in the same manner except that the combination of I)] was changed. Then, a magenta transferred image and a black and white image were obtained in the same manner as in Example 1 except that the photothermographic material and the image receiving member were prepared and the photothermographic material was exposed and developed.

Table 4 shows the sensitivities of the black and white image and the magenta transferred image as relative values. However, the sensitivity of the black and white image of Sample No. 23 was set to 100, and the sensitivity was determined by the point of fog +0.2. Also, the highest concentration (D
The value obtained for a magenta transfer image by color heat development is shown as "max)".

As is clear from Table 4, comparative samples (No. 14, 15, 17, 18, 20, 21) in which the sensitizing dye (I) and the sensitizing dye (II) which are the compounds of the present invention are not used in combination. , 23, 24, 2
6, 27, 29, 30), a large decrease in sensitivity due to color heat development is observed.

Even when the sensitizing dye (I) and the sensitizing dye (II) are used in combination, the sensitizing dye (No. 13 and 16) is different from the comparative sample (No. 13, 16) in which the photosensitive silver halide is outside the present invention. The samples (Nos. 19, 22, 25, 28) of the present invention using the photosensitive silver halide of the present invention (Nos. 19, 22, 25 and 28) in combination with (I) and (II) have improved desensitization due to color heat development and are excellent. It can be seen that it is a photothermographic material. Furthermore, among the photosensitive silver halides of the present invention, it is found that the core / shell type photosensitive silver halide is particularly good with little desensitization. On the other hand, even with the core / shell type photosensitive silver halide, the grain size is 0.
It is understood that the comparative sample (No. 31) of 5 μm, which is outside the scope of the present invention, has high sensitivity but the maximum density of the magenta transfer image is small, and cannot be put to practical use.

Example 3 Compound of the present invention [sensitizing dye (I) and sensitizing dye (I
A photosensitive silver halide dispersion was prepared in the same manner as in Example 1 except that the combination of [I)] was changed to the combination shown in Table 5 below.

[Preparation of Dye-Donating Substance Dispersion Liquid-2] 30.0 g of the exemplified dye-donating substance was dissolved in 30.0 g of tricresyl phosphate and 90.0 ml of ethyl acetate, and the same as in Example 1 was mixed with 460 ml of an aqueous gelatin solution containing a surfactant. After dispersing with an ultrasonic homogenizer, ethyl acetate was distilled off and water was added to make 500 ml.

[Preparation of Photothermographic Material-2] 40.0 ml of the silver halide emulsion dispersion, 25.0 ml of the organic silver salt dispersion-1 of Example 1, and 50.0 of the dye-donor dispersion-2.
ml, and polyethylene glycol 300 (manufactured by Kanto Chemical Co., Inc.) 4.20 g as a heat solvent, 10 wt% methanol solution of 1-phenyl-4,4-dimethyl-3-pyrazolidone 1.
5 ml The same hardening agent as in Example 1 (3.00 ml) and guanidine trichloroacetic acid (10% by weight in water-alcohol solution 20.0 ml) were added, and the amount of silver was adjusted on the undercoated 180 μm thick photographic polyethylene terephthalate film. The coating was carried out so as to obtain 2.50 g / m ^2, and 12 kinds of photothermographic materials-2 of Sample Nos. 32 to 43 shown in Table 5 below were prepared.

[Preparation of Image Receiving Member-2] The following layers were sequentially coated on a transparent polyethylene terephthalate film having a thickness of 100 μm.

(1) A layer made of polyacrylic acid. (7.00 g / m ² ) (2) Layer made of cellulose acetate. (4.00 g / m ² ) (3) Styrene and N-benzyl-N, N-dimethyl-N-
Of (3-maleimidopropyl) ammonium chloride
Layer consisting of 1: 1 copolymer and gelatin.

(Copolymer 3.00 g / m ² Gelatin 3.00 g / m ² ) The above 12 types of photothermographic materials-2 were exposed to 1,600 CMS through a step wedge and heated on a heat block at 150 ° C. for 1 minute. After that, it is laminated with the image receiving member-2 in which water is immersed, and pressure-bonded at 50 ° C. and 500 g to 800 g / cm ² .
When it was quickly peeled off for 30 seconds, a negative image of a yellow step wedge was obtained on the surface of the image receiving member.

On the other hand, the same exposed light-sensitive material was subjected to wet black-and-white development processing in the same manner as in Example 1 to obtain a black-and-white image.

In Table 5, the sensitivities of the black and white image and the yellow transferred image obtained by heat development are shown in relative values. However, the sensitivity of the black and white image of sample No. 40 was set to 100, and the sensitivity was determined by the point of fog +0.2.

As is clear from Table 5, even in the photothermographic material in which the dye-donor substance was used in place of the reducing dye substance, the silver halide emulsion containing the photosensitive silver halide grains of the present invention was used in the invention. Among the compounds, the sensitizing dye (I) and the sensitizing dye (I) of the compound of the present invention are compared with the comparative samples (No. 40 to 43) using only the sensitizing dye (I) or the sensitizing dye (II). The samples (No. 32 to 39) used in combination with II) have less desensitization due to heat development, and also have a good sensitizing effect on photosensitive silver halide, and are high-sensitivity photothermographic materials. I know there is.

Example 4 In Example 3, the silver halide emulsions shown in Table 6 below and the compounds of the present invention [sensitizing dye (I) and sensitizing dye (I
A photosensitive silver halide dispersion liquid was prepared in the same manner except that the combination of I)] was replaced. Then, a yellow transfer image and a black and white image were obtained in the same manner as in Example 3 except that the photothermographic material and the image receiving member were prepared and the photothermographic material was exposed and developed.

Table 6 shows the sensitivities of the black and white image and the yellow transferred image as relative values. However, the sensitivity of the black and white image of sample No. 54 was set to 100, and the sensitivity was determined at the point of fog +0.2. Also, the highest concentration (D
The value obtained for a yellow transfer image by color heat development is shown as "max)".

As is clear from Table-6, comparative samples (No. 45, 46, 48, 49, 51, 52) in which the sensitizing dye (I) and the sensitizing dye (II) which are the compounds of the present invention are not used in combination. , 54, 55, 5
7, 58, 60), a large decrease in sensitivity is observed due to color heat development.

Even when the sensitizing dye (I) and the sensitizing dye (II) are used in combination, the sensitizing dye (No. 44, 47) is different from the comparative sample (No. 44, 47) in which the photosensitive silver halide is outside the scope of the present invention. The samples (Nos. 50, 53, 56 and 59) of the present invention using the photosensitive silver halide of the present invention (No. 50, 53, 56, 59) in combination with (I) and (II) have improved desensitization by color heat development and are excellent. It can be seen that it is a photothermographic material. Furthermore, among the photosensitive silver halides of the present invention, it is found that the core / shell type photosensitive silver halide is particularly good with little desensitization. On the other hand, even with the core / shell type photosensitive silver halide, the grain size is 0.
It can be seen that the comparative sample (No. 62) of 5 μm, which is outside the scope of the present invention, has high sensitivity but the maximum density of the yellow transferred image is small, and cannot be put to practical use.

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Ken Iwagaki 1 Sakura-cho, Hino-shi, Tokyo Within Konishi Roku Photo Industry Co., Ltd. (56) Reference JP-A-59-114734 (JP, A) JP-A-59- 120039 (JP, A) JP 60-48561 (JP, A) JP 60-258535 (JP, A) JP 60-263937 (JP, A) JP 61-262739 (JP, A)

Claims (1)

[Claims] 1. A small number of silver halide emulsion layers in a photothermographic material.
At least one of them has a silver iodide content of 4 to 40 mol%, and
Photosensitive silver halide grains with an average grain size of 0.4 μm or less
And at least a compound represented by the following general formula (I)
At least one compound represented by the following general formula (II)
It also contains a combination of 1 and
Characterized in that it does not substantially contain a potash agent precursor
Photothermographic material to be used. General formula (I)Where R₁Is a hydrogen atom, an alkyl group, an aryl group or
Represents a telocyclic group, R₂And R₃Are alkyl groups
Represent. Y₁And Y₂Is sulfur atom or selenium atom, respectively
Represents a child. Z₁, Z₂, Z₃And Z_FourAre hydrogen atoms,
Halogen atom, hydroxyl group, alkoxy group, acyl
Group, alkoxycarbonyl group, alkoxycarbonyl group
Mino group, acylamido group, aryl group, alkyl group or
Represents a cyano group. However, Z₁And Z₂Or Z₃And Z_FourThroat
Either one or both are connected to each other
You may form a ring. X₁ Represents an anion, m is 0
Or represents an integer of 1. General formula (II)Where R_Four, R_Five, R₆And R₇Is a hydrogen atom or
Represents a rukyll group. Y₃Is a nitrogen atom, a sulfur atom or selenium
Represents a hydrogen atom, but Y₃Is a sulfur atom or a selenium atom
When R above_FourShall not be included. Z_Five, Z₆, Z₇and
Z₈Are hydrogen atom, halogen atom, hydroxyl
Group, alkoxy group, acyl group, acylamido group, acyl
Oxy group, alkoxycarbonyl group, aryloxy group
Rubonyl group, alkoxycarbonylamino group, aryl
Represents a group, an alkyl group, a cyano group or a sulfonyl group
You However, Z_FiveAnd Z₆Or Z₇And Z₈Either one or
Both may be linked together to form a ring.
Yes. X₂ Represents an anion, and n is an integer of 0 or 1.
Represent.