JP2791676B2 - Photothermographic material - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photothermographic material, and more particularly to a photothermographic silver halide photographic material having improved storage stability and providing a high maximum density and a low minimum density. About the material.

[Prior Art] A light-sensitive material capable of obtaining a visible image to be developed by simply heating the exposed silver halide photographic light-sensitive material without subjecting it to a bath treatment is a heat-developable silver halide photographic light-sensitive material. Well known as a material.

Thermally developed silver halide photographic materials
Called. ) Contains a light-sensitive silver halide emulsion, a binder and a reducing agent on a support, and if necessary, a non-light-sensitive organic silver salt.

A thermally developed silver halide photographic material used for color photography (hereinafter referred to as a "thermally developed color sensitive material").
If necessary, a dye-donating substance that forms or releases a dye is used as necessary according to the development of the silver halide agent. However, other dye-donating substances are not necessarily required for the heat-sensitive color photographic material in which the reducing agent itself is a dye-donating substance.

In a heat-sensitive color light-sensitive material, a dye formed or released as a result of thermal development is diffused imagewise by superposing the light-sensitive material and a dye image-receiving material having an image-receiving layer capable of receiving a dye on a support. Transfer is also performed, and this method is preferably used because a clear color image can be obtained.

However, such a heat-sensitive material as described above contains a reducing agent in a photosensitive layer including a silver halide emulsion layer or in an adjacent layer (a reducing agent which releases a reducing agent during thermal development in the developing agent). Contains a large amount of a precursor, which causes various problems as compared with silver halide photographic materials for bath processing. Among them, an undesirable desensitizing effect on silver halide during storage of the photographic material. However, it has a disadvantage that the desensitization is remarkable especially when stored for a long time in a high humidity state.

Conventionally, various attempts have been made to prevent fogging or desensitization during storage of a heat-sensitive material. For example, JP-A-61-112140 discloses a technique using silver halide in which the surface of silver halide grains is a layer containing high iodine. JP-A-61-38942 discloses a compound such as 1-phenyl-5-mercaptotetrazole which can form a sparingly soluble silver salt on the surface of a substantially light-insensitive silver salt such as silver chloride. A technique for containing silver salt particles having adsorbed thereon is disclosed.

However, even with these techniques, a sufficient effect cannot be obtained on the decrease in sensitivity during storage, and the effect of preventing the desensitization by the reducing agent when stored under high humidity conditions is insufficient. there were.

In order to obtain a sufficient storage stability improvement effect by the above two techniques, the surface of the photosensitive silver halide grains must be remarkably increased in iodine, a poorly soluble compound can be adsorbed on the surface, or a large amount of silver salt grains can be obtained. It has to be used, and as a result, there arises a problem that the developability is lowered, and the processing stability is easily lowered due to the influence of the developing temperature and the temperature around the heat developing machine.

JP-A-61-193143 discloses a method in which a sensitizing dye is present during the formation of silver halide grains,
It is described that the sensitivity of the heat-sensitive material using silver halide grains obtained by this method, even when stored at, for example, a temperature of 40 ° C. and a relative humidity of 70%, is reduced. However, there is a problem that the sensitizing dye added in the formation stage in the silver halide grains is not completely removed even in the desalting step and is spectrally sensitized by the sensitizing dye.

That is, the heat-sensitive material is often exposed and heat-developed by an apparatus in which an exposure system and a heat developing machine are combined in one apparatus. In such a case, the exposure of the heat-sensitive material is performed by the heat developing machine. Due to the residual heat to be dispersed, the exposure is performed in an exposure system which is in a relatively high temperature state and the temperature is apt to fluctuate. Therefore, the temperature dependence of the photographic performance of the heat-sensitive material at the time of exposure becomes particularly important. Generally, the exposure and temperature dependence of a silver halide photographic material greatly depend on the type of sensitizing structure used, and the type of sensitizing dye is greatly restricted in order to sufficiently satisfy the temperature dependence. Naturally, there is a disadvantage that the sensitizing dye used in forming silver halide grains is greatly restricted.

[Problems to be Solved by the Invention] An object of the present invention is to firstly provide a heat-sensitive material in which a desensitizing effect of a reducing agent during storage is prevented. Another object of the present invention is to provide a heat-sensitive material having improved desensitization in the case where the heat-sensitive material is used.

A second object of the present invention is to provide a heat-sensitive material which gives a high maximum density and a low minimum density.

[Means for Solving the Problems] An object of the present invention is to provide a photothermographic material having a binder, a photosensitive silver halide and a reducing agent on a support, in an amount of 1 × 10 ⁻³ per mol of silver halide. Achieved by a photothermographic material characterized by having at least one silver halide emulsion layer containing a photosensitive silver halide chemically sensitized in combination with at least a sulfur sensitizer in the presence of from 5 to 5 mg of inorganic sulfur. Is done.

 Hereinafter, the present invention will be described more specifically.

In the present invention, the chemical sensitization needs to be performed in the presence of inorganic sulfur, but the term `` inorganic sulfur '' used in the present invention refers to a so-called elemental sulfur that does not form a compound with other elements. means. Thus, sulfur-containing compounds known in the art as photographic additives, such as sulfides, sulfuric acid (or salts thereof),
Sulfurous acid (or its salt), thiosulfuric acid (or its salt), sulfonic acid (or its salt), thioether compound, thiourea compound, mercapto compound, sulfur-containing heterocyclic compound and the like are included in the inorganic sulfur in the present invention. Not.

It is known that simple sulfur used as inorganic sulfur in the present invention has several allotropes, but any of these allotropes may be used.

Among the above allotropes, those which are stable at room temperature are α-sulfur belonging to the orthorhombic system, and it is preferable to use this α-sulfur in the present invention.

When adding the inorganic sulfur according to the present invention, it may be added as it is, but it is more preferable to add it as a solution.
Inorganic sulfur is insoluble in water, but is known to be soluble in carbon disulfide, sulfur chloride, benzene, diethyl ether, ethanol, etc., and it is preferable to add it after dissolving in these solvents. Of these inorganic sulfur solvents, ethanol is particularly preferably used in terms of absorption and photographic effects.

The amount of the inorganic sulfur to be added can be arbitrarily selected depending on the type of silver halide emulsion to be applied, the size of the expected effect, and the like, but is preferably 1 × 10 ⁻⁵ mg to 10 mg per mol of silver halide, and more preferably Preferably, it is 1 × 10 ⁻³ mg to 5 mg.

The inorganic sulfur can be added in any step as long as the silver halide grains are chemically sensitized in the presence of the inorganic sulfur. Specifically, before the formation of silver halide grains, during the formation of silver halide grains, during the period from the end of silver halide grain formation to before the desalting step, and from the desalting step to the start of chemical sensitization, chemical sensitization is performed. Any time selected from the start of sensitization and during chemical sensitization may be used. It is preferably added at any time selected from the end of silver halide grain formation to before the desalting step, from after the desalting step to before the start of chemical sensitization, at the start of chemical sensitization and during chemical sensitization.

More preferably, in order to obtain a particularly high maximum density and a low fog effect without a decrease in sensitivity, from the desalting step to before the start of chemical sensitization, from the start of chemical sensitization and during chemical sensitization. Any time selected is preferred, most preferably at the start of chemical sensitization.

In the present invention, inorganic sulfur can be used alone as a sensitizer, but it is preferable to use a chemical sensitizer, such as a chalcogen sensitizer, at the time of chemical sensitization. The chalcogen sensitizer is a general term for a sulfur sensitizer, a selenium sensitizer, and a tellurium sensitizer. For photographic use, a sulfur sensitizer and a selenium sensitizer are preferable. Known sulfur sensitizers can be used, and examples thereof include thiosulfate, allylthiocarbazide, thiourea, allyl isothiocyanate, cystine, p-toluenethiosulfonate, and D-danine. In addition, U.S. Patent Nos. 1,574,944 and 2,410,689
Nos. 12,278,947, 2,728,668, 3,501,313,
No. 3,656,955, West German Application Publication (OLS) No. 1,442,869, JP-A-56-24937, and JP-A-55-45016 can also be used. The addition amount of the sulfur sensitizer varies over a considerable range depending on various conditions such as pH, temperature, and the size of silver halide grains, but as a guide, the amount is from 10 ^-7 mol to 10 ^-1 per mol of silver halide. Molar amounts are preferred.

Examples of selenium sensitizers include aliphatic isoselenosinates such as allyl isoselenocyanate, selenoureas, selenoketones, selenoamides, selenocarboxylates and esters, selenophosphates, diethyl selenide, and diethyl selenide. Selenides such as diselenide can be used, and specific examples thereof are described in U.S. Pat.
Nos. 1,574,944, 1,602,592, and 1,623,499. Further, reduction sensitization can be used in combination. The reducing agent is not particularly limited, but includes known stannous chloride, thiourea dioxide, hydrazine, polyamine and the like. In addition, a noble metal compound, for example, a platinum compound, a palladium compound or the like can be used in combination.

In the present invention, it is preferable to carry out chemical sensitization using inorganic sulfur and a sulfur sensitizer in combination, or to carry out chemical sensitization using inorganic sulfur, a sulfur sensitizer and a gold compound in combination.

In the present invention, the conditions of the chemical sensitization to be carried out can be arbitrarily selected depending on the silver halide grains to be used and the expected photographic characteristics.
C. to 70.degree. C., pH 5.0 to 7.5, pAg 6.0 to 8.5. For the time of chemical sensitization, usually, under the conditions of the chemical sensitization, the photographic characteristics at each time step are examined in advance, and the most preferable photographic characteristics (for example, low fog, high sensitivity, high contrast, etc.) are obtained. Although the time is set, the production stability, the work efficiency in the process, and the like are often taken into consideration, and the standard is tens of minutes to several hours.

In the present invention, chemical sensitization is preferably performed in the presence of a nitrogen-containing heterocyclic compound, and more preferably, chemical sensitization is performed in the presence of a mercapto compound.

Preferred specific examples of such a nitrogen-containing heterocyclic compound are shown below.

The above compound is preferably 0.001 to 10 mmol, more preferably 0.01 to 5 mol per mol of silver halide during chemical sensitization.
Used in the millimolar range.

The photosensitive silver halide emulsion according to the present invention can be spectrally sensitized to blue, green, red and near-infrared regions using a known sensitizing dye.

Representative spectral sensitizing dyes that can be used in the present invention include, for example, cyanine, merocyanine, complex (that is, trinuclear or tetranuclear) cyanine, holopolocyanine, styryl, hemicyanine, oxonol, and the like.

The preferable addition amount of these sensitizing dyes is 1 × 10 ^-6 mol to 1 mol per 1 mol of the photosensitive silver halide or silver halide forming component. More preferably, 1 × 10 ⁻⁵ to 1 × 10
^-1 mole.

The sensitizing dye may be added at any stage during the preparation of the silver halide emulsion. That is, it may be at any time such as at the time of forming silver halide grains, at the time of removing soluble salts, at the start of chemical sensitization, at the time of chemical sensitization, or after the end of chemical sensitization.

The photosensitive silver halide used in the present invention includes, for example, silver bromide, silver iodobromide, silver chloride, silver chlorobromide, silver chloroiodide, silver chloroiodobromide, etc. Any silver halide may be used, but silver bromide, silver iodobromide and silver chloroiodobromide are particularly preferred. The content of silver iodide in the silver halide is preferably 0 to 15 mol%, particularly preferably 0 to 5 mol%.

Furthermore, even if the crystal structure of the silver halide grains is uniform up to the inside, the inside and the outside have a heterogeneous layered structure, and are described in British Patent No. 635,841, U.S. Patent No. 3,622,318. Such a so-called conversion type may be used. Further, any of a type in which a latent image is mainly formed on the surface and an internal latent image type in which a latent image is formed inside a particle may be used. Grains having a multilayer structure in which the halogen composition of the grains is different from the surface and inside, for example, as core-shell silver halide grains, those in which the halogen composition changes stepwise,
Alternatively, a continuously changed one is used.

The shape is a cube, sphere, octahedron, dodecahedron,
What has a crystal habit clearly, such as a tetrahedron, a 24-hedron, and the like, can be used. Examples of the silver halide in this nest include those described in JP-A-60-215948.

Also, for example, JP-A-58-111933, JP-A-58-111934,
JP-A-58-108526, Research Disclosure
No. 22534, etc., have two parallel crystal planes, and each of these crystal planes is a particle having an area larger than that of another single crystal of this particle, and its aspect ratio, i.e., particle Tabular silver halide grains having a diameter to thickness ratio of 5: 1 or more can also be used.

The photosensitive silver halide grains used in the present invention may be coarse grains or fine grains, but the preferred grain size is from about 0.05 μm to about 2 μm, more preferably about 0.08 μm 0.50.5 μm. However, in the present invention, “particle size” refers to the length of one side of a cube having the same volume. The particle size distribution may be wide (polydisperse emulsion) or narrow (monodisperse emulsion), but monodisperse emulsions are preferred for the purposes of the present invention.

Particularly, silver halide grains having a variation coefficient of the grain size distribution of 20% or less are preferable. Here, the coefficient of variation is And is a measure of monodispersity.

The photosensitive silver halide can be adjusted by an arbitrary method such as a single jet method and a controlled double jet method generally used in the field of photographic technology.

During the formation of these photosensitive silver halide grains, gold,
Heavy metal ions such as platinum, lead, cadmium, rhodium, and iridium can be present, but iridium ions are particularly preferred because they do not reduce the sensitivity during high-illuminance exposure. Examples of the preferably used compound giving iridium ion include, for example, hexachloroiridium (II
I) acid salt or hexachloroiridium (IV) acid salt [for example, K ₂ IrCl ₆ , K ₃ IrCl ₆ , Li ₃ IrCl ₆ , Na ₃ IrCl ₆ , (NH ₄ ) ₂
IrCl ₆ , Li ₂ IrCl ₆ , and Na ₂ IrCl ₆ ]. These iridium compounds are added in an amount of from 10 ^-8 to 10 ^-4 mol per mol of silver halide.

During the formation of silver halide grains, as a silver halide solvent to control the growth of the grains, for example, ammonia, rodankari, rodanammon, thioether compounds (for example, U.S. Patent Nos. 3,271,157 and 3,574,628,
Nos. 3,704,130, 4,297,439 and 4,276,374) thione compounds (for example, JP-A-53-144319,
53-82408, 55-77737, etc.), and amine compounds (for example, JP-A-54-100717) can be used. In addition to the silver halide solvent, a compound which controls the crystal habit by adsorbing on the grain surface, for example, a cyanine sensitizing dye, a tetrazaindene compound, a mercapto compound, or the like can be used at the time of grain formation.

In the present invention, as another method for preparing silver halide grains, a photosensitive silver salt-forming component may be allowed to coexist with an organic silver salt described later to form photosensitive silver halide on a part of the organic silver salt.

The reducing agent (and / or a reducing agent precursor that releases the reducing agent at the time of thermal development) used in the heat-sensitive material of the present invention is:
Although it is possible to use those usually used in the field of the heat-sensitive material, it is preferable to use a reducing agent precursor from the viewpoint of storability.

Examples of the reducing agent that can be used in the present invention include, for example, U.S. Patent Nos. 3,531,286, 3,761,270, and 3,764,
Nos. 328, RD (Research Disclosure) No. 12146, No. 15180, No. 15127 and JP-A-56
No. 27132, U.S. Pat.Nos. 3,342,599 and 3,719,49
No. 2, each of JP-A-53-135628, JP-A-57-79035, etc., p-phenylenediamine-based and p-aminophenol-based developing agents, phosphoramidophenol-based, sulfonamidoaniline-based Developing agents, hydrazone-based color developing agents and precursors thereof, or phenols, sulfonamide phenols, or polyhydroxybenzenes, naphthols, hydroxybisnaphthyls and methylenebisnaphthols, methylenebisphenols, ascorbic acid, 3-Pyrazolidones and pyrazolones can be used.

Particularly preferred reducing agents are (p-N, N-dialkylamino) phenylsulfamic acid salts described in JP-A-56-146133 and JP-A-62-227141, which are represented by the following general formula [I]
Are represented.

In the formula, R ¹ and R ² represents an alkyl group having carbon atoms which may have a substituent 1 to 30 (preferably 1 to 4), R ¹
And R ² may be closed to form a heterocyclic ring. 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 acylamide group, a sulfonamide group, an alkylsulfonamide group or the number of carbon atoms which may have a substituent Represents an alkyl group of 1 to 30 (preferably 1 to 4), and R ³ and R ¹ and R ⁵ and R ² may each be closed to form a heterocyclic ring. M is an alkali metal atom (Na, K, Li
Atom) represents a compound containing an ammonium group, a nitrogen-containing organic base or a quaternary nitrogen atom.

The nitrogen-containing organic base represented by M in the above general formula [I] is an organic compound containing a nitrogen atom exhibiting basicity capable of forming an inorganic salt and a salt. Particularly important organic bases include amine compounds. Can be Primary amines, secondary amines, tertiary amines, and the like are used as chain amine compounds, and pyridine, quinoline, and the like are typical examples of typical heterocyclic organic bases as cyclic amine compounds.
Piperzine, imidazole and the like. In addition, compounds such as hydroxylamine, hydrazine and amidine are also useful as amines. As the salt of a nitrogen-containing organic base, an inorganic acid salt of an organic base as described above (for example, hydrochloride,
Sulfate, nitrate, etc.) are preferably used.

On the other hand, the fourth compound represented by M in the general formula [I]
Examples of the compound containing a secondary nitrogen atom include a salt or a hydroxyl compound of a nitrogen compound having a tetravalent covalent bond.

Next, preferred specific examples of the reducing agent represented by the general formula [I] are shown below.

Further, in the present invention, a substance represented by the following general formula [II] can be used as a reducing agent.

General formula [II] (Car) -NHSO ₂ -Dye In the formula, Car is a reducing group that is oxidized to release a dye when silver halide and / or an organic silver salt is reduced, and Dy
e is a diffusible dye residue. Specific examples of the above-mentioned reducing dye releasing compound are described in, for example, JP-A-57-179840 and JP-A-58-179840.
No. 116537, JP-A-59-60434, JP-A-59-65839,
JP-A-59-71046, JP-A-59-87450, JP-A-59-88
No. 730, JP-A-59-123837, JP-A-59-165054, JP-A-59-165055, and JP-A-62-203158.

In addition to these reducing agents, a metal compound as disclosed in Japanese Patent Application No. 63-104645 can be added for the purpose of obtaining a high image density.

 Two or more reducing agents may be used simultaneously.

The amount of the reducing agent used in the heat-sensitive color light-sensitive material of the present invention is arbitrarily dependent on the type of photosensitive silver halide used, the type of organic acid silver salt and the type of other additives. Although it can be selected, it is usually preferably in the range of 0.01 to 100 mol, preferably 0.1 to 10 mol, per 1 mol of the light-sensitive silver halide.

Further, the binder used in the heat-sensitive material of the present invention is polyvinyl butyral, polyvinyl acetate, ethyl cellulose, polymethyl methacrylate, cellulose acetate butyrate, polyvinyl alcohol, polyvinyl pyrrolidone, gelatin, gelatin derivatives such as phthalated gelatin, cellulose derivatives. And synthetic or natural high-molecular substances such as protein, starch, and gum arabic. These can be used alone or in combination of two or more.

The preferred amount of the binder to be used is generally 0.5 g to 50 g, more preferably 1 g to ²⁰ g, per m ^{2 of the} support.

In the heat-sensitive material of the present invention, various organic silver salts can be used as needed.

Organic silver salts that can be used in the heat-sensitive material of the present invention include JP-A-53-4921, JP-A-49-52626, and JP-A-52-52626.
-141222, 53-36224 and 53-37626, 52
-141222, JP-A-53-36224 and JP-A-53-37610, and U.S. Patent Nos. 3,330,633 and 3,794,496,
No. 4,105,451, etc., such as silver salts of long-chain aliphatic carboxylic acids and silver salts of carboxylic acids having a heterocyclic ring, such as those described in the specifications, such as silver laurate, silver myristate, silver palmitate Silver stearate, silver arachidonic acid, silver behenate, silver α- (1-phenyltetrazolethio) acetate and the like; silver aromatic carboxylate such as silver benzoate and silver phthalate; 45−12700
Nos. 45-18416 and 45-22185, JP-A-52-137321
No., JP-A-58-118638, JP-A-58-118639, U.S. Pat.
There is a silver salt of an imino group described in each publication of 4,123,274.

In addition, a silver complex compound having a stability constant of 4.5 to 10.0 as described in JP-A-52-31728, a silver salt of imizolinthion as described in U.S. Pat. No. 4,168,980, and the like are used.

Among the above organic silver salts, a silver salt of an imino group is preferable, and a silver salt of benzotriazole and its derivative is more preferable. In particular, benzotriazole, 5-methylbenzotriazole and its derivatives, sulfobenzotriazole and its derivatives, and silver salts of N-alkylsulfamolebenzotriazole and its derivatives are preferable.

The organic silver salts used in the present invention may be used alone or in combination of two or more. Further, a silver salt may be prepared in an appropriate binder and used as it is without isolation, or the isolated one may be used after being dispersed in a binder by an appropriate means. Examples of the dispersing means include, but are not limited to, those using a ball mill, a sand mill, a colloid mill, and a vibration mill.

The amount of the organic silver salt to be used is generally preferably from 0.01 mol to 500 mol, more preferably from 0.1 to 100 mol, per 1 mol of the photosensitive silver halide. More preferably, it is 0.3 to 30 mol.

When the heat-sensitive material of the present invention is a heat-sensitive color material, it contains a dye-providing substance. Since the dye-providing substance is generally used together with the reducing agent, the dye-providing substance is selected depending on the reducing agent. When the reducing agent also serves as a dye-donating substance as represented by the general formula [II], a dye-donating substance is not necessarily required separately from the reducing agent.

As the dye-providing substance used in the present invention, for example,
62-44737, JP-A-62-129852, couplers forming non-diffusible dyes described in JP-A-62-169158,
For example, a leuco dye described in U.S. Pat.No. 475,441, or an azo dye used in a heat-developing dye bleaching method described in, for example, U.S. Pat.No. 4,235,957 can be used as the dye-providing substance, but a diffusible dye is more preferable. It is preferable to use a diffusion type dye-providing substance which forms or releases a dye, and particularly, a compound which forms a diffusible dye by a coupling reaction is preferably used.

Hereinafter, the diffusion type dye-providing substance that can be used in the present invention will be described. As the diffusion type dye-providing substance, any substance which 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 is provided. well,
Depending on the form of the reaction, a negative dye-donor acting on a positive function (ie, one that forms a negative dye image when negative silver halide is used) and a positive acting on a negative function Type dye-providing substances (that is, those which form a positive dye image when a negative-type silver halide is used).

As negative dye-donating substances, for example, U.S. Pat.
Nos. 3,079 and 4,439,513, JP-A-59-60434, and 59-6
No. 5839, No. 59-71046, No. 59-87450, No. 59-88730
Nos. 59-123837, 59-124329, 59-165054
And reducing dye-releasing compounds described in the specifications such as JP-A Nos.

As another negative type dye-providing substance, for example, U.S. Pat.
4,474,867, JP-A-59-12431, JP-A-59-48765, and
9-174834, 59-776642, 59-159159, 59
Coupling dye-releasing compounds described in the specification such as -231040.

Still another particularly preferred negative dye-donor substance of the coupling dye-forming compound is represented by the following general formula (A).

Formula (A) CpJB) In the formula, Cp represents an organic group capable of forming a diffusible dye by reacting (coupling reaction) with an oxidized form of a reducing agent, and J is substituted with an active site of a coupler. B represents a divalent linking group, and B represents a ballast group. Here, the ballast group is
A substance that does not actually diffuse a dye-donor substance during thermal development processing. It exhibits a function (such as a sulfo group) depending on the nature of the molecule or a group that exhibits the function depending on the size (a large number of carbon atoms). Group). The coupler residue represented by Cp preferably has a molecular weight of 700 or less, more preferably 500 or less, in order to improve the diffusibility of the formed dye.

The ballast group is preferably a group having 8 or more, more preferably 12 or more carbon atoms, or a sulfo group, a group containing both of them is more preferable, and a group that is a polymer chain is more preferable.

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

In the general formula (B) CpJY l _ZL) formula, Cp, J is the same as defined in the general formula (I), Y is an alkylene group, an arylene group or aralkylene group, l a is 0 or 1 And 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 compounds represented by formulas (a) and (b) include JP-A-59-24339 and JP-A-59-24339.
9-1818345, 60-2950, JP-A-61-57943, 6
Nos. 1-59336, U.S. Pat.Nos. 4,631,251, 4,650,748,
There are those described in each specification of 4,656,124, especially U.S. Pat.No.4,656,124, U.S. Pat.No.4,631,251,
The polymer type dye-providing substances described in the specifications of the above-mentioned 4,650,748 are preferred.

Examples of the positive dye-donating substance include, for example, JP-A-59-1984.
Nos. 554430 and 59-165054, and dye developing compounds described in JP-A-59-165054, for example, JP-A-59-154445, and diffusible dyes by intramolecular nucleophilic reaction described in JP-A-59-766954 and the like. A compound to be released, for example, a cobalt complex compound described in JP-A-59-116655 or a compound disclosed in JP-A-59-124327.
And compounds which lose their dye releasing ability when oxidized as described in JP-A Nos. 59-152440 and 59-152440.

As the residue of the diffusible dye in the dye-donating substance used in the present invention, in order to improve the diffusibility of the dye, preferably has a molecular weight of 800 or less, more preferably 600 or less, azo dye, Residues include 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 a temporarily shortened form that can be recolored during thermal development or transfer. Further, these dye residues are preferably chelateable dye residues described in JP-A-59-48765 and JP-A-50-124337, for the purpose of increasing the light fastness of an image. It is.

These dye-providing substances may be used alone or in combination of two or more. The amount of use is not limited, and the kind of the dye-providing substance, whether it is used alone or in combination of two or more, or whether the photographic constitution layer of the heat-sensitive material of the present invention is a single layer or
The amount may be determined depending on the number of layers or more, and for example, the amount of use is 0.005 to 50 g, preferably 0.1 to 10 g per 1 m ² .

In the present invention, an antifoggant is preferably contained in or adjacent to a silver halide emulsion layer containing a silver halide emulsion chemically sensitized in the presence of inorganic sulfur. Examples of the antifoggant which can be used in the present invention include higher fatty acids described in U.S. Pat. No. 3,645,739, mercury salts described in JP-B-47-11113, and JP-A-51-47419. No. 3,700,457, JP-A-5
No. 1-50725, mercapto compound-releasing compound described in No. 49-125016, arylsulfonic acid described in No. 49-125016,
Lithium carboxylate described in JP-A-51-47419, British Patent No. 1,455,271, oxidizing agent described in JP-A-50-1001019, sulfinic acids or thiosulfonic acids described in JP-A-53-19825 2-thiouracils described in No. 51-3223, sulfur alone described in 51-26019, 51-42529, 51-81124, and disulfide and polysulfide compounds described in 55-93149. Rosin or diterpenes described in JP-A-51-57435, polymer acids having free carboxyl groups or sulfonic acid groups described in JP-A-51-104338, U.S. Pat.
No. 4,138,265, thiazoline thione described in
4-51821, 1,2,4-triazole or 5-mercapto-1,2,4 described in U.S. Pat.No.4,137,079.
Triazole, thiosulfinic acid esters described in JP-A-55-140883, 1,2,
3,4-thiatriazoles, 59-46641, 59-5723
And dihalogen compounds and trihalogen compounds described in JP-A Nos. 3 and 59-57234, thiol compounds described in 59-111636 and hydroquinone derivatives described in 60-198540.

Among them, in the present invention, a nitrogen-containing heterocyclic mercapto compound having a development accelerating ability or an antifogging function is preferably used.

Various additives are added to the heat-sensitive material of the present invention as needed. Examples of such additives include known heat solvents, development accelerators, acid or base precursors, hardeners, optical brighteners, antihalation agents, filter dyes, antistatic agents, matting agents, dye image stabilizers, and the like. Photographic additives can be used. Specifically, RD (Research Disclosure) magazine vol.170, published in June 1978, No.17029
JP-A-62-135825, JP-A-63-316848, and Japanese Patent Application No. 63-19338.

The heat-sensitive material of the present invention comprises (a) a photosensitive silver halide,
(B) It contains a reducing agent and (c) a binder. Further, if necessary, the composition preferably contains (d) a dye-providing substance and / or (e) organic silver. These may be basically contained in one heat-developable photosensitive layer, but need not necessarily be contained in a single photographic component layer. For example, the heat-developable photosensitive layer is divided into two layers, a), (b), (c),
The component (e) may be contained in one of the heat-developable photosensitive layers, and the other layer adjacent to the photosensitive layer may contain the dye-donating substance (d). May be contained in a layer adjacent to the photosensitive layer containing, or as long as they can react with each other, they may be contained in two or more constituent layers.

Further, the photothermographic layer may be provided in two or more layers of a low-sensitivity layer and a high-sensitivity layer, and a high-density layer and a low-density layer.

In the case of a color light-sensitive material having two or more heat-developable light-sensitive layers, the heat-developable light-sensitive material of the present invention generally includes three heat-developable light-sensitive layers having different color sensitivities. Dyes having different hues are formed or released by the development.

When the heat-sensitive material of the present invention is a full-color light-sensitive material, a blue light-sensitive layer, a green light-sensitive layer, a red light-sensitive layer and an infrared light-sensitive layer can be used in any combination.

The combination of each photosensitive layer and the coloring dye is also optional, and a yellow dye-providing substance, a magenta dye-providing substance, and a cyan dye-providing substance can be freely combined with each photosensitive layer.

Usually, a yellow dye is combined with the blue photosensitive layer, a magenta dye is combined with the green photosensitive layer, and a cyan dye is combined with the red photosensitive layer. However, the present invention is not limited thereto.

In the heat-sensitive material of the present invention, in addition to the heat-developable photosensitive layer,
A non-photosensitive layer such as an undercoat layer, an intermediate layer, a protective layer, a filter layer, a backing layer, and a release layer can be provided. The photothermographic layer and the non-photosensitive layer are coated on a support. The same method as used for coating and preparing a general silver halide photosensitive material can be applied.

Generally, the exposure for obtaining a photographic image is a tungsten lamp,
Any of various known light sources including infrared light, such as a cathode ray tube flying spot, a light emitting diode, and laser light (eg, a gas laser, a YAG laser, a dye laser, and a semiconductor laser) can be used. Also electron beam,
The exposure may be performed by light emitted from a phosphor excited by X-rays, γ-rays, α-rays, or the like. The exposure time is 1 second exposure time from 1/1000 second to be used in a normal camera course, shorter exposure than 1/1000 sec, for example, exposure of 1 / 10-1 / 10 ⁸ seconds with a xenon flash lamp or a cathode ray tube It can also be used. If necessary, the spectral composition of light used for exposure can be adjusted by a color filter. The heat-sensitive material of the present invention is particularly suitable for scanner exposure using a laser.

When the heat-sensitive material of the present invention has at least one infrared-sensitive layer, it is preferable to use a semiconductor laser as a light source for exposure to infrared light. When a full-color photosensitive material is used, a plurality of light sources are required. For example, a visible light emitting laser can be used in combination.
Preferably, a gas laser (He-Ne laser, Ar ⁺ ion laser, He-Cd laser, or the like), a semiconductor laser, a semiconductor laser and a second harmonic generation element (SHG element), or the like can be used.

The heat-sensitive material of the present invention is usually preferably 80 ° C. after imagewise exposure.
~ 200 ° C, more preferably 100 ° C ~ 170 ° C,
Preferably from 1 second to 180 seconds, more preferably from 1.5 seconds to 12 seconds
It is developed only by heating for 0 seconds. Transfer of the diffusible dye to the image receiving layer, which is a preferred embodiment of the developed color light-sensitive material, may be performed simultaneously with thermal development by bringing the image receiving member into close contact with the photosensitive surface of the photosensitive material and the image receiving layer during thermal development, The image may be transferred by closely contacting the image receiving member after thermal development, or by closely contacting after supplying water and, if necessary, by heating. Further, pre-heating may be performed in a temperature range of 70 ° C. to 180 ° C. before exposure. Also, JP-A-60-143338,
As described in Japanese Patent Application No. 60-3644, the photosensitive material and the image receiving member may be preheated at a temperature of 60 ° C. to 250 ° C. immediately before the thermal development transfer in order to enhance mutual adhesion.

Various heating means can be used for the heat-sensitive material of the present invention.

As the heating means, all methods applicable to ordinary heat-sensitive materials can be used.For example, the heating means is brought into contact with a heated block or plate, is brought into contact with a heat roller or a heat drum, or is passed through a high-temperature atmosphere. Or using high-frequency heating, and further providing a conductive layer containing a conductive substance such as carbon black on the back surface of the photosensitive material of the present invention or the back surface of the thermal transfer-like image receiving member, and utilizing Joule heat generated by energization. You can also. The heating pattern is not particularly limited, and is preheated in advance.
After that, including a method of heating again, a short time at high temperature, or a long time at low temperature, continuously rising, continuously falling or repeating them, and even discontinuous heating is possible, but a simple pattern is preferable. Further, a system in which exposure and heating proceed simultaneously may be used.

The image-receiving layer of the image-receiving member effectively used in the present invention may be any as long as it has a function of receiving the dye in the heat-developable photosensitive layer released or formed by thermal development.
For example, a polymer containing a tertiary amine or a quaternary ammonium salt and described in US Pat. No. 3,709,690 is preferably used. A typical image receiving layer for diffusion transfer is obtained by mixing a polymer containing an ammonium salt, a tertiary amine or the like with gelatin or polyvinyl alcohol and coating the mixture on a support. Another useful dye accepting substance includes a substance formed of a heat-resistant organic polymer having a glass transition temperature of 40 ° C. or more and 250 ° C. or less described in JP-A-57-207259.

These polymers may be supported on a support as an image receiving layer, or may be themselves used as a support.

Examples of the heat-resistant polymer substance, polystyrene,
A polystyrene derivative having a substituent having 4 or less carbon atoms,
Polyacetals such as polyvinylcyclohexane, polydivinylbenzene, polyvinylcarbazole, polyallylbenzene, polyvinylformal and polyvinylbutyral, polyvinyl chloride, chlorinated polyethylene, poly (trifluorochloroethylene), polyacrylonitrile, poly-
N, N-dimethylallylamido, p-cyanophenyl group,
Polyacrylate having pentachlorophenyl group and 2,4-dichlorophenyl group, polyacrylchloroacrylate, polymethylmethacrylate, polyethylmethacrylate, polypropylmethacrylate, polypropylmethacrylate, polyisobutylmethacrylate, polyisobutylmethacrylate, poly-tert-butylmethacrylate , Polycyclohexyl methacrylate, polyethylene glycol dimethacrylate, poly-2-cyano-
Polyesters such as ethyl methacrylate, polyethylene isophthalate, polysulfone, bisphenol A
Examples include polycarbonates such as polycarbonates, polyanhydrides, polyamides, and cellulose acetates. Also, "Polymer Handbook, Second Edition" (edited by Joy Blind Wrap, E.H.
Sands Publishing @ Polymer Handbook 2nd ed. (J. Brandrup,
EHImmergut) Synthetic polymers with a glass transition temperature of 40 ° C or higher described in John Wiley & Sons ＆ are also useful.
Generally, the molecular weight of the polymer substance is 2000 to 2000.
00 is useful. These polymer substances may be used alone or as a blend of two or more kinds, or two or more kinds may be used in combination or as a copolymer.

Particularly preferred image receiving layers include a layer composed of polyvinyl chloride described in JP-A-59-223425 and a layer composed of polyvinyl chloride described in JP-A-60-19223.
138 publication.

These polymers can be used as a support and image-receiving layer (image-receiving member), in which case the support may be formed of a single layer or may be formed of a plurality of layers. .

As the support for the image receiving member, any material such as a transparent support and an opaque support may be used. For example, films such as polyethylene terephthalate, polycarbonate, polystyrene, polyvinyl chloride, polyethylene, and polypropylene, and these supports Supports containing pigments such as titanium oxide, barium sulfate, calcium carbonate, talc, etc., baryta paper, RC paper laminated with thermoplastic resin containing pigment on paper, cloth, glass, aluminum, etc. Metals, etc., and an electron beam-curable resin composition containing a pigment applied on these supports, and a cured support, and a support provided with a coating layer containing the pigment on these supports Body and the like. Further, the cast-coated paper described in JP-A-62-283333 is also useful as a support.

Further, an electron beam-curable resin composition containing a pigment is applied on paper, and the support is cured, or the pigment-coated layer is provided on paper, and the electron beam-curable resin composition is provided on the pigment applied layer. Can be used as an image receiving member because the resin layer itself can be used as an image receiving layer.

The heat-sensitive material of the present invention is disclosed in RD (Research Disclosure Magazine) 15107, JP-A-57-198458 and JP-A-57-207250.
And a so-called mono-sheet type photothermographic material in which a photosensitive layer and an image receiving layer are provided on the same support as described in JP-A-61-80148.

EXAMPLES Hereinafter, specific examples of the present invention will be described. However, the present invention is not limited to this.

Example 1 Monodisperse emulsion EM of octahedral silver iodobromide having an average particle size of 0.16 μm by an ammonia method and a simultaneous mixing method in which pAg is controlled.
P-1 (AgI composition 2.1 mol%, variation coefficient of particle size distribution 10%)
Was prepared.

To the obtained silver iodobromide monodispersed emulsion EMP-1 were added α-sulfur and sodium thiosulfate in the amounts shown in Table 1 as chemical sensitizers, and each was subjected to surface chemical sensitization under optimum conditions. Silver iodobromide emulsions EM-1 to EM-6 were prepared. (At the time of chemical sensitization
(pAg = 7.0) At the end of the chemical sensitization, 1.2 g of 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene ST-4 was added per mol of silver halide as a stabilizer.

Next, using the obtained EM- to -6, heat-existing color light-sensitive materials 1 to 6 having the composition shown in Table 2 were prepared.

On the other hand, an image receiving layer having the structure shown in Table 3 was applied on an art paper of 120 g / m ² to prepare an image receiving material-1.

After short-time light wedge exposure of ^10-6 seconds is applied to each of the heat-sensitive color light-sensitive materials 1 to ⁶ , the image receiving material-1 and each heat-sensitive color light-sensitive material are overlapped, and heated at 150 ° C. for 60 seconds. Development processing was performed.

After the heat development, the image receiving member was peeled off from the heat-sensitive color photographic material to obtain a negative cyan image on the image receiving layer. The reflection density and the sensitivity were measured. The results (immediate performance) are shown in Table-4.

On the other hand, each of the heat-existing color light-sensitive materials 1 to 6 was stored at 50 ° C. and 20% RH or 40 ° C. and 80% RH for 7 days, respectively, and subjected to short-time light wedge exposure in the same manner as described above. Then, heat development was performed, and the reflection density and sensitivity were measured. Table 4 shows the results.

From the results shown in Table 4, all of the heat-sensitive color light-sensitive materials 3 to 6 using the silver halide emulsion chemically sensitized in the presence of the inorganic sulfur of the present invention showed immediate performance, and the comparative samples 1 and the present invention It can be seen that the maximum concentration and the sensitivity are higher than that of Sample 2.
On the other hand, 50 ℃, relative humidity 20% and 40 ℃, relative humidity 80%
When each is stored for 7 days, the heat-sensitive material of the present invention is:
It can be seen that the increase in the minimum density and the decrease in the maximum density are suppressed, and the desensitizing effect during storage is significantly improved.
In particular, when inorganic sulfur was added in an amount of 0.002 mg or more per mole of silver halide, it was found that the desensitizing effect during high-humidity storage was particularly prevented.

Example 2 A surface chemical sensitizer was changed from a combination of inorganic sulfur and sodium thiosulfate to a combination of inorganic sulfur, sodium thiosulfate and sodium chloroaurate (III), and the amounts shown in Table 5 were respectively added. In the same manner as in Example 1, silver iodobromide emulsions EM-7 to -11 were prepared, and in the same manner as in Example 1, heat-sensitive color light-sensitive materials 7 to 11 were obtained. The obtained heat-existing color light-sensitive material was processed in the same manner as in Example 1, and the immediate performance, or the sensitivity and reflection density under the conditions were measured. The results are shown in Table-6.

As is clear from the results in Table 6, the heat-sensitive color light-sensitive materials (8 to 11) using the silver halide emulsion chemically sensitized in the presence of inorganic sulfur as in Example 1 were compared. Sample 7
And the highest concentration and storage performance were better.

Example-3 Antifoggants shown below in a silver halide emulsion layer
1, the heat-existing color photographic materials 12 to 12 were prepared in the same manner as in Example 2 except that antifoggant-2 and antifoggant-3 were added in the following amounts.
Using the obtained heat-existing color photographic material prepared in No. 16, processing was carried out in the same manner as in Example 2, and the sensitivity and the reflection density were measured. The results are shown in Table-7.

As is clear from Table 7, the effect of the present invention can be obtained even in a system in which an antifoggant is added to the emulsion layer.

Example-4 At the start of the chemical sensitization of a silver halide emulsion, α-sulfur, sodium thiosulfate, sodium chloroaurate (III) and a sensitizing dye shown in Table-8 were added in amounts shown in Table-8. Silver halide emulsions EM-12 to EM-31 were prepared in the same manner as in Example 3 except that surface sensitization was performed to the optimum sensitivity. Next, using each of the obtained emulsions EM-12 to -31, and using the same procedure as in Example 3 except that 0.04 g of an antifoggant-1 was further added to the protective layer, heat-sensitive color photographic materials 17 to 36 were prepared. Then, the sensitivity and the reflection density were measured in the same manner as in Example 3. Table 9 shows the obtained results.

As is clear from the results in Table 9, the effects of the present invention can be obtained even when a silver halide emulsion which has been subjected to chemical ripening in the presence of a sensitizing dye is used.

Example -5 A monodisperse silver tetrabromide emulsion EMP-2 having an average particle size of 0.21 µm and having a mean particle size of 0.21 µm was obtained by controlling the pAg in the same manner as in Example 1 by the ammonia method and the simultaneous mixing method (coefficient of variation in particle size distribution: 12%) Was prepared. However, when the average particle size is 0.13 μm, K ₃ IrCl
₆ was added in an amount of 10 ^-6 mol per mol of silver halide.

On the other hand, a silver bromoiodide emulsion having an average particle size of about 0.16 μm was used as a seed emulsion, silver bromide was shelled by an ammonia method with pAg controlled, and a cubic silver iodobromide monodisperse emulsion EMP- having an average particle size of 0.24 μm was used. 3 (silver iodide content: 1.4 mol%, variation coefficient of grain size distribution: 9%) was prepared.

Using chemical sensitizers and spectral sensitizers of the types and amounts shown in Table 10 using EMP-1, EMP-2 and EMP-3, respectively,
Green, red and infrared-sensitive silver halide emulsions EM-32 to EM
-40 was adjusted. However, at the end of chemical ripening, 1.6 g of ST-4 was added as a stabilizer per mole of silver halide.

Next, using each of the obtained photosensitive silver halide emulsions, a multilayer heat-sensitive color light-sensitive material 37 having a layer constitution shown in Table 11 was used.
Created ~ 39. Table 12 shows the combinations of the photosensitive silver halide emulsions.

Evaluation was carried out in the same manner as in Example 1 using each of the obtained heat-sensitive color photographic materials 37 to 39. The results are shown in Table-12.

In Table 12, the measurement lights B, G, and R are the reflection density measurements of the obtained yellow, magenta, and cyan dye images with blue, green, and red monochromatic lights, respectively. Represents From the results shown in Table 12, it was found that the effects of the present invention can be obtained also in the multilayer thermosensitive color light-sensitive material.

Example -6 Same as Example 5 except that, during chemical sensitization, nitrogen-containing heterocyclic compounds (exemplified compounds M-12, M-61) were further added in amounts shown in Table 13 to carry out chemical sensitization. Thus, silver halide emulsions EM-41 to 49 and EM-50 to 58 were prepared. Using the obtained silver halide emulsion, heat-existing color light-sensitive materials 40 to 45 were formed in the same layer constitution as in Example-5. (Combinations of the respective photosensitive silver halide emulsions are shown in Table 14.) However, the infrared-sensitive silver halide emulsion of the infrared-sensitive layer was replaced with the blue-sensitive silver halide emulsion shown in Table 13 and was replaced by blue. A photosensitive layer,
The following yellow filter dye YF-1 is used for the second intermediate layer.
0.21 g was added.

Next, evaluation was performed in the same manner as in Example-5, and the obtained results are shown in Table-14.

From the results shown in Table 14, by performing chemical sensitization in the presence of a further nitrogen-containing heterocyclic compound at the time of chemical sensitization,
It can be seen that the remarkable effect of the present invention can be obtained even more.

When the emulsion chemically sensitized with the nitrogen-containing heterocyclic mercapto compound M-61 is used for the nitrogen-containing heterocyclic compound M-12, the effect of the present invention can be obtained without lowering the maximum density. You can see that. Further, it can be seen that the decrease in sensitivity when stored is smaller when M-61 is used and inorganic sulfur is used.

[Effects of the Invention] As described in detail above, the present invention prevents the desensitizing effect of the reducing agent during storage, particularly during storage under high humidity conditions, and provides a high maximum concentration and a minimum concentration. A light-sensitive material can be provided.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03C 1/498 G03C 1/08 G03C 8/40

Claims (1)

(57) [Claims] 1. A photothermographic material comprising a support, a binder, a photosensitive silver halide and a reducing agent, wherein at least sulfur is increased in the presence of 1 × 10 ^-3 mg to 5 mg of inorganic sulfur per mole of silver halide. A photothermographic material comprising at least one silver halide emulsion layer containing a photosensitive silver halide chemically sensitized in combination with a sensitizer.