JP2000112058A - Heat-developable photosensitive material, recording material, and method for decoloring merocyanine dye - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat-developable photosensitive material containing a heat-decolorable dye which exhibits irreversible heat decolorability by incorporating a specified merocyanine dye and a base precursor into at least one nonphotosensitive layer. SOLUTION: This heat-developable photosensitive material has a substrate, a photosensitive layer containing a silver halide and a reducing agent and at least one nonphotosensitive layer containing a merocyanine dye represented by the formula and a base precursor. In the formula, R1 is H, an aliphatic group, an aromatic group, -NR21R26, -OR21 or -SR21, R21 and R26 are each H, an aliphatic group or the like or form a nitrogen-containing heterocycle by bonding to each other, R2 is H, an aliphatic group or an aromatic group, L1 and L2 are each an optionally substituted methine, Z1 is an atomic group forming a 5- or 6-membered nitrogen-containing heterocycle, Z2 is an atomic group forming a 5- or 6-membered ring and (n) is 1-4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a photothermographic material,
The present invention relates to a recording material and a method for decolorizing a merocyanine dye.

[0002]

2. Description of the Related Art Photothermographic materials have been proposed for a long time, and are described, for example, in US Pat. Nos. 3,152,904 and 345.
No. 7075 and each of B.I. "Thermal Proceed Silver System" by Shely
ssed Silver Systems) "(Imaging Processes and Mats
erials) Neblette 8th edition, edited by Sturge, V. Walworth, A. Shepp, 2nd edition
, 1996). The photothermographic material generally comprises a catalytically active amount of a photocatalyst (eg, silver halide), a reducing agent, a reducible silver salt (eg, an organic silver salt), a color tone controlling silver color tone, a binder matrix. It has a photosensitive layer dispersed therein. The photothermographic material is
After the image exposure, the resultant is heated to a high temperature (for example, 80 ° C. or higher), and a black silver image is formed by a redox reaction between silver halide or a reducible silver salt (which functions as an oxidizing agent) and a reducing agent. . The oxidation-reduction reaction is promoted by the catalytic action of the latent image of silver halide generated by exposure. for that reason,
A black silver image is formed in the exposed areas.

[0003] The heat development processing has the advantage that processing liquid in the wet development processing is not required, and processing can be performed simply and quickly. However, in the field of photographic technology, an image forming method by wet development processing is still mainstream. The heat development process has unsolved problems that are not found in the wet development process.

One of the problems is the problem of decolorization of dyes. It is usually necessary to add a dye to a photographic light-sensitive material for the purpose of filtering, preventing halation and preventing irradiation. Dyes are added to the non-photosensitive layer and function in image exposure. If the dye whose function has been completed remains in the photographic material, the formed image will be colored by the dye. Therefore, it is necessary to remove the dye from the photographic light-sensitive material in the development processing. In the wet development processing, the dye can be easily removed from the photographic material using a processing solution. On the other hand, it is very difficult (substantially impossible) to remove the dye in the heat development treatment.

[0005] In recent photographic techniques, particularly in the technical fields of medical photography and printing photography, simple and rapid development processing is required. However, the improvement of wet development processing has almost reached its limit. For this reason, in the technical field of medical photography and printing photography, an image forming method by thermal development has been renewed. In order to solve the problem that removal of the dye is extremely difficult in the heat development, a method of decoloring the dye by heating in the heat development has been proposed. For example, in the specification of US Pat. No. 5,135,842,
A method of decoloring a polymethine dye having a specific structure by heating is disclosed. U.S. Pat. No. 5,314,795,
Nos. 5,324,627 and 5,384,237 disclose a method of decoloring a polymethine dye by heating using a carbanion generator.

[0006]

According to the method of decoloring a dye by heating proposed in the prior art, the decolorization of the dye is insufficient or, on the contrary, the stability of the dye is insufficient, so There was a problem that the dye was discolored during storage of the material. Further, in the polymethine dye used in the conventional technique, a decomposition product of the dye remaining after decoloring has a slight light absorption, and there is also a problem that a color remains in an image (particularly a highlight portion). Was. In addition, the prior art dyes have the problem of recoloring after thermal development, especially on contact with acids.

It is an object of the present invention to provide a photothermographic material which contains an excellent thermo-decolorable dye which does not have the above-mentioned problems in a non-photosensitive layer. Another object of the present invention is to provide a novel heat-decolorable recording material. It is a further object of the present invention to provide a method for rapidly and substantially irreversibly decolorizing merocyanine dyes that are stable at room temperature by heating.

[0008]

An object of the present invention is to provide a photothermographic material described in the following item (1), a recording material described in the following item (2), and a decolorization of the merocyanine dye described in the following items (3) and (4). Achieved by the method.

(1) A photothermographic material comprising a support, a photosensitive layer containing silver halide and a reducing agent, and a non-photosensitive layer, wherein at least one non-photosensitive layer has the following formula (I) A photothermographic material comprising a merocyanine dye represented by the formula: and a base precursor.

[0010]

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Wherein R ¹ is a hydrogen atom, an aliphatic group, an aromatic group, —NR ₂₁ R ₂₆ , —OR ₂₁ or —SR ₂₁ ;
R ₂₁ and R ₂₆ are each independently a hydrogen atom, an aliphatic group or an aromatic group, or R ₂₁ and R ₂₆ are combined to form a nitrogen-containing heterocyclic ring; R ² is a hydrogen atom, L ¹ and L ² are each independently an optionally substituted methine, and the methine substituent is bonded to the unsaturated aliphatic ring or the unsaturated heterocyclic ring; Z ¹ is an atomic group forming a 5- or 6-membered nitrogen-containing heterocyclic ring, and the nitrogen-containing heterocyclic ring may be condensed with an aromatic ring; The ring and the fused ring thereof may have a substituent; Z ² is an atomic group forming a 5- or 6-membered ring;
2, 3 or 4.

(2) A recording material having a recording layer on a support, wherein at least one recording layer contains a merocyanine dye represented by the following formula (I) and a base precursor, and the merocyanine dye is a molecule or a solid. A recording material, wherein the recording material is dispersed in the recording layer in a state of fine particles.

[0013]

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In the formula, R ¹ is a hydrogen atom, an aliphatic group, an aromatic group, —NR ₂₁ R ₂₆ , —OR ₂₁ or —SR ₂₁ ;
R ₂₁ and R ₂₆ are each independently a hydrogen atom, an aliphatic group or an aromatic group, or R ₂₁ and R ₂₆ are combined to form a nitrogen-containing heterocyclic ring; R ² is a hydrogen atom, L ¹ and L ² are each independently an optionally substituted methine, and the methine substituent is bonded to the unsaturated aliphatic ring or the unsaturated heterocyclic ring; Z ¹ is an atomic group forming a 5- or 6-membered nitrogen-containing heterocyclic ring, and the nitrogen-containing heterocyclic ring may be condensed with an aromatic ring; The ring and the fused ring thereof may have a substituent; Z ² is an atomic group forming a 5- or 6-membered ring;
2, 3 or 4.

(3) A method for decolorizing a merocyanine dye represented by the following formula (I) by applying a base to the merocyanine dye under heating conditions:

[0016]

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In the formula, R ¹ is a hydrogen atom, an aliphatic group, an aromatic group, —NR ₂₁ R ₂₆ , —OR ₂₁ or —SR ₂₁ ;
R ₂₁ and R ₂₆ are each independently a hydrogen atom, an aliphatic group or an aromatic group, or R ₂₁ and R ₂₆ are combined to form a nitrogen-containing heterocyclic ring; R ² is a hydrogen atom, L ¹ and L ² are each independently an optionally substituted methine, and the methine substituent is bonded to the unsaturated aliphatic ring or the unsaturated heterocyclic ring; Z ¹ is an atomic group forming a 5- or 6-membered nitrogen-containing heterocyclic ring, and the nitrogen-containing heterocyclic ring may be condensed with an aromatic ring; The ring and the fused ring thereof may have a substituent; Z ² is an atomic group forming a 5- or 6-membered ring;
2, 3 or 4.

(4) The method for decolorizing a merocyanine dye according to item (3), wherein the color of the dye is decolorized by an intramolecular ring closing reaction by the heating.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention uses a merocyanine dye represented by the following formula (I).

[0020]

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In the formula (I), R ¹ is a hydrogen atom, an aliphatic group, an aromatic group, —NR ₂₁ R ₂₆ , —OR ₂₁ or —S
R ₂₁ . R ₂₁ and R ₂₆ are each independently a hydrogen atom, an aliphatic group or an aromatic group, or R ₂₁ and R ₂₆ combine to form a nitrogen-containing heterocyclic ring. R ¹ is-
It is preferably NR ₂₁ R ₂₆ , —OR ₂₁ or —SR ₂₁ . R ₂₁ is preferably an aliphatic group or an aromatic group, and is an alkyl group, a substituted alkyl group, an aralkyl group,
More preferably, it is a substituted aralkyl group, an aryl group or a substituted aryl group. R ₂₆ is preferably a hydrogen atom or an aliphatic group, and more preferably a hydrogen atom, an alkyl group or a substituted alkyl group. R ₂₁
The nitrogen-containing heterocyclic ring formed by bonding of R and R ₂₆ is preferably a 5- or 6-membered ring. The nitrogen-containing heterocyclic ring may have a hetero atom other than nitrogen (eg, an oxygen atom, a sulfur atom).

In the present specification, "aliphatic group" means an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an alkynyl group, a substituted alkynyl group, an aralkyl group or a substituted aralkyl group. In the present invention, an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an aralkyl group or a substituted aralkyl group is preferred, and an alkyl group, a substituted alkyl group, an aralkyl group or a substituted aralkyl group is more preferred. A chain aliphatic group is preferred over a cyclic aliphatic group. The chain aliphatic group may have a branch. The alkyl group has 1 to 30 carbon atoms.
Is preferably 1 to 20, more preferably 1 to 15, and most preferably 1 to 12. The alkyl part of the substituted alkyl group is the same as the alkyl group.

The alkenyl group and the alkynyl group preferably have 2 to 30 carbon atoms, and preferably have 2 to 20 carbon atoms.
Is more preferably 2 to 15, further preferably 2 to 12, and most preferably 2 to 12.
The alkenyl part of the substituted alkenyl group and the alkynyl part of the substituted alkynyl group are the same as the alkenyl group and the alkynyl group, respectively. The number of carbon atoms of the aralkyl group is preferably from 7 to 35, more preferably from 7 to 25, further preferably from 7 to 20, and most preferably from 7 to 15. The aralkyl part of the substituted aralkyl group is the same as the aralkyl group.

Examples of the substituent of the aliphatic group (substituted alkyl group, substituted alkenyl group, substituted alkynyl group, substituted aralkyl group) include a halogen atom (fluorine atom, chlorine atom, bromine atom), hydroxyl, nitro, carboxyl, Includes sulfo, acyl, alkoxy, alkoxycarbonyl, alkylthio, alkylthiocarbonyl, aryloxy, aryloxycarbonyl and carbamoyl groups. Carboxyl and sulfo may be in the form of a salt. The cation forming a salt with carboxyl and sulfo is preferably an alkali metal ion (eg, sodium ion, potassium ion).

As used herein, the term "aromatic group" means an aryl group (phenyl, naphthyl, etc.) or a substituted aryl group. The aryl group has 6 to 3 carbon atoms.
It is preferably 0, more preferably 6 to 20, still more preferably 6 to 15, and 6
Most preferably, it is from 12 to 12. The aryl part of the substituted aryl group is the same as the aryl group. Examples of the substituent of the aromatic group (substituted aryl group) include a halogen atom (fluorine atom, chlorine atom, bromine atom), hydroxyl,
Includes nitro, carboxyl, sulfo, alkyl, acyl, alkoxy, alkoxycarbonyl, alkylthio, alkylthiocarbonyl, aryloxy, aryloxycarbonyl and carbamoyl groups. Carboxyl and sulfo may be in the form of a salt. The cation forming a salt with carboxyl and sulfo is preferably an alkali metal ion (eg, sodium ion, potassium ion).

In the formula (I), R ² is a hydrogen atom, an aliphatic group or an aromatic group. The definitions of the aliphatic group and the aromatic group are as described above. R ² is preferably a hydrogen atom or an aliphatic group, more preferably a hydrogen atom or an alkyl group, further preferably a hydrogen atom or an alkyl group having 1 to 15 carbon atoms, and a hydrogen atom Is most preferred. In the formula (I), R ⁵ is an aliphatic group. The definition of the aliphatic group is as described above. R ⁵ is preferably a substituted alkyl group. From the viewpoint of easy synthesis, R ⁵ represents —CHR
And particularly preferably a substituted alkyl group having the same definition as ² -CO-R ^1.

In the formula (I), L ¹ and L ² are each independently methine which may be substituted. Examples of the substituent of methine include a halogen atom, an aliphatic group and an aromatic group. The definitions of the aliphatic group and the aromatic group are as described above. The substituents of methine may combine to form an unsaturated aliphatic ring or an unsaturated heterocyclic ring. Unsaturated aliphatic rings are preferred over unsaturated heterocycles. The ring to be formed is preferably a 5- or 6-membered ring, more preferably a cycloheptene ring or a cyclohexene ring. It is particularly preferred that methine is unsubstituted or forms a cycloheptene ring or a cyclohexene ring. In the formula (I), Z ¹ has 5 members or 6 members.
Group forming a nitrogen-containing heterocyclic ring. Examples of the nitrogen-containing heterocycle include an oxazole ring, a thiazole ring, a selenazole ring, a pyrroline ring, an imidazole ring and a pyridine ring. Five-membered rings are preferred over six-membered rings. Nitrogen-containing heterocycles include aromatic rings (benzene rings and naphthalene rings)
May be condensed. The nitrogen-containing heterocycle and its condensed ring may have a substituent. Examples of the substituent include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom), a hydroxyl, a nitro, a carboxyl, a sulfo, and an alkyl group. Carboxyl and sulfo may be in the form of a salt. The cation forming a salt with carboxyl and sulfo is preferably an alkali metal ion (eg, sodium ion, potassium ion). In the formula (I),
Z ² is an atomic group forming a 5- or 6-membered ring. Examples of the atomic group forming a 5- or 6-membered ring include a pyrazolone ring, a pyridone ring, an isoxazolone ring, a pyrazolidinedione ring, a pyrazolopyridone ring, a rhodanin ring, a barbituric acid ring, a thiobarbituric acid ring, and Includes indandione rings. Five-membered rings are preferred over six-membered rings. 5
An aromatic ring (a benzene ring or a naphthalene ring) may be condensed to the atomic group forming a six- or six-membered ring. The nitrogen-containing heterocycle and its condensed ring may have a substituent.
Examples of the substituent include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom), a hydroxyl, a nitro, a carboxyl, a sulfo, and an alkyl group. Carboxyl and sulfo may be in the form of a salt. The cation forming a salt with carboxyl and sulfo is preferably an alkali metal ion (eg, sodium ion, potassium ion). In the formula (I), n is 1, 2, 3 or 4.

The following are specific examples of the merocyanine dye represented by the formula (I).

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Synthesis Example 1 Synthesis of Merocyanine Dye (1) A solution of chloroacetic acid amide obtained by reacting 41.8 ml of chloroacetic acid chloride with 88.2 ml of 2,4,5-trichloroaniline in 250 ml of toluene , 2,
88.2 ml of 3,3-trimethylindolenine was added and the mixture was refluxed under heating for 7 hours. The crystals were filtered off and washed with acetonitrile to give 143.1 g (66%) of the quaternary salt of indolenine. In a mixed solution of 300 ml of acetic acid and 141.5 ml of acetic anhydride, 142.4 g of 5-anilino-N-phenyl-2,4-pentadienylideneiminium chloride, 121.2 ml of pyridine and 1-phenyl-3-cyano 92.6 g of -2-pyrazolin-5-one was added and the mixture was stirred at room temperature. The precipitated crystals were taken out and washed with acetonitrile, and 124 g (60%) of pyrazolone-pentamethine-
A monoanil intermediate was obtained. Dimethylacetamide 30m
To l, 4.32 g of indolenine quaternary salt, 3.82 g of monoanil intermediate and 1.40 ml of triethylamine were added, and the mixture was stirred at room temperature. The obtained dye was extracted with ethyl acetate and purified by column chromatography (silica gel). Yield 6.0 g (13%), λ max 696.8 n
m, ε14600 (methanol).

Other merocyanine dyes can be synthesized in the same manner as in Synthesis Example 1 described above. As for the synthesis method, the methods described in JP-A-50-145124, JP-B-59-28899, U.S. Pat.

In the present invention, the merocyanine dye or a salt thereof can be decolorized by the action of a base under heating conditions. According to the study of the present inventor, the merocyanine dye of the present invention is characterized in that the active methylene group in the merocyanine dye is deprotonated by the action of a base, and the nucleophile generated thereby nucleophilically attacks the methylene chain in the molecule, It has been found that by forming an inner ring, the color is lost. Accordingly, any base that can be used in this reaction can be used as long as it can deprotonate the active methylene group in the dye. The number of ring members newly formed by the intramolecular ring closure reaction is not particularly limited, but is preferably a 5- to 7-membered ring, more preferably a 5- or 7-membered ring. The substantially colorless compound thus formed is a stable compound and does not return to the original merocyanine dye. Therefore,
In the decoloring method of the present invention, there is no problem that the decolored substance recolors. The decolorization reaction proceeds in a solvent system or a non-solvent system. When performing the decoloring reaction in a solvent system, it is preferable to heat a solution of the merocyanine dye and a base (or a base precursor). As the solvent, a substance (eg, dimethylsulfoxide, dimethylacetamide) that dissolves a merocyanine dye and a base (or a base precursor) and is liquid at a heating temperature (described below) is used. When performing the decoloring reaction in a non-solvent system, it is preferable to heat a sheet (recording material or photosensitive material) coated with a solution of a merocyanine dye and a base (or a base precursor). Implementation in a non-solvent system, that is, the details of the heat-decolorable recording material and the photothermographic material will be described later.

The heating temperature in the decolorization reaction is 40 to 2
The temperature is preferably 00 ° C., more preferably 80 to 150 ° C., further preferably 100 to 130 ° C., and most preferably 115 to 125 ° C. The heating time is preferably from 5 to 120 seconds, more preferably from 10 to 60 seconds, and
More preferably, it is 2 to 30 seconds, and 15 to 2 seconds.
Most preferably, it is 5 seconds. In the case of the photothermographic material (details will be described later), heating for thermal development is performed.
Further, in order to generate a base, it is preferable to use a pyrolytic base precursor (details will be described later). In such a case, the actual heating temperature and heating time are determined in consideration of the temperature and time required for thermal development or the temperature and time required for thermal decomposition.

The base necessary for the decolorization reaction is a base in a broad sense, and includes a nucleophile (Lewis base) in addition to the base in a narrow sense. When the base coexists with the merocyanine dye, the decoloring reaction slightly proceeds even at room temperature. Therefore, keeping the base physically or chemically separated from the merocyanine dye,
It is preferable that the base and the merocyanine dye are brought into contact (reaction) during heating (when the color is to be erased). Means for physically isolating the base include the use of microcapsules, addition of a heat-fusible substance into fine particles, or addition to a layer different from the layer containing a merocyanine dye in a recording material or photosensitive material. There are means. Microcapsules include those that burst by pressure and those that burst by heating. Since the decoloring reaction is carried out under heating conditions, it is convenient to use microcapsules that rupture by heating (thermoresponsive). For isolation, one of the base and the merocyanine dye is encapsulated in a microcapsule. When the outer shell of the microcapsule is opaque, it is preferable to encapsulate the base in the microcapsule. For thermoresponsive microcapsules, see Hiroyuki Moriga, Introduction to Specialty Paper Chemistry (Showa 50
Year) and JP-A-1-150575. A base or a merocyanine dye (preferably a base) may be added to the fine particles of a heat-fusible substance such as wax to isolate the fine particles. The melting point of the heat-fusible substance is between room temperature and the above-mentioned heating temperature. When a layer containing a merocyanine dye and a layer containing a base are separated from each other in a recording material or a photosensitive material, a barrier layer containing a heat-fusible substance is preferably provided between the layers.

However, chemical isolation means is easier to implement and is preferable to such physical isolation means. As a chemical isolation means, use of a base precursor is typical. Although there are various types of base precursors, since the decoloring reaction is performed under heating conditions, it is convenient to use a precursor that generates (or releases) a base by heating. A typical example of a base precursor that generates a base by heating is a pyrolytic (decarboxylation) base precursor composed of a salt of a carboxylic acid and a base.
When the decarboxylation type base precursor is heated, the carboxyl group of the carboxylic acid undergoes a decarboxylation reaction to release an organic base. As the carboxylic acid, sulfonylacetic acid or propiolic acid, which is easily decarboxylated, is used. The sulfonylacetic acid and the propiolic acid preferably have, as a substituent, an aromatic group (aryl group or unsaturated heterocyclic group) that promotes decarboxylation. The base precursor of sulfonyl acetate is disclosed in JP-A-59-168441, and the base precursor of propiolate is disclosed in JP-A-59-168441.
There is a description in each of JP-A-180537. The base component of the decarboxylation type base precursor is preferably an organic base, and more preferably amidine, guanidine or a derivative thereof. The organic base is preferably a diacid, triacid or tetraacid, more preferably a diacid, and most preferably an amidine derivative or a guanidine derivative.

The precursor of the diacid, triacid or tetraacid base of the amidine derivative is described in JP-B-7-59.
No. 545. The precursor of a diacid group, triacid group or tetraacid group of a guanidine derivative is described in JP-B-8-10321. The diacid base of the amidine derivative or guanidine derivative is represented by (A)
It consists of two amidine moieties or guanidine moieties, (B) a substituent of the amidine moieties or guanidine moieties, and (C) a divalent linking group connecting the two amidine moieties or guanidine moieties. Examples of the substituent (B) include an alkyl group (including a cycloalkyl group), an alkenyl group, an alkynyl group, an aralkyl group, and a heterocyclic residue. Two or more substituents may combine to form a nitrogen-containing heterocyclic ring. The linking group (C) is preferably an alkylene group or a phenylene group. Hereinafter, examples of the diacid base precursor of the amidine derivative or the guanidine derivative will be described.

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The use amount (mole) of the base precursor is preferably 1 to 100 times, more preferably 3 to 30 times the use amount (mole) of the merocyanine dye. The merocyanine dye can be used for various applications by utilizing the above-described decolorization reaction. For example, a solution of a merocyanine dye and a base precursor can be used as the thermal decolorizable ink. Further, a solution obtained by applying a solution of a merocyanine dye and a base precursor to a transparent support can be used as a heat-decolorable sheet (filter). Further, a merocyanine dye and a base precursor can be applied to a thermal decoloring type recording material. The heat-decolorable recording material has a recording layer on a support (preferably a transparent support). The merocyanine dye is dispersed in the recording layer in the form of a molecule or solid fine particles. In the case of molecular dispersion, a solution of a merocyanine dye is added to the coating solution for the recording layer. In the case of dispersion in the form of solid fine particles, a dispersion of solid fine particles of a merocyanine dye is added to the coating solution for the recording layer. The base precursor is preferably dispersed in the recording layer in the form of solid fine particles. The recording layer preferably further contains a binder. As the binder, a hydrophilic polymer (eg, polyvinyl alcohol, gelatin) is preferably used. By performing imagewise heating, the heat-decolorable recording material can form an image by decoloring the heated portion. Imagewise heating uses a thermal head used in a facsimile or thermal printer,
It can be easily implemented.

A particularly preferred embodiment of the decolorization of the merocyanine dye of the present invention is a photothermographic material. A merocyanine dye and a base precursor are added to the non-photosensitive layer of the photothermographic material to make the non-photosensitive layer function as a filter layer or an antihalation layer. A photothermographic material generally has a non-photosensitive layer in addition to a photosensitive layer. The non-photosensitive layer is composed of (1) an overcoat layer provided on the photosensitive layer (farther than the support), (2) an intermediate layer provided between a plurality of photosensitive layers, and (3) And (4) an undercoat layer provided between the photosensitive layer and the support, and (4) a back layer provided on the opposite side of the photosensitive layer. The filter layer is provided on the photosensitive material as the layer (1) or (2). The antihalation layer is provided on the photosensitive material as the layer (3) or (4). The merocyanine dye and the base precursor are preferably added to the same non-photosensitive layer. However, they may be separately added to two adjacent non-photosensitive layers. Further, a barrier layer may be provided between the two non-photosensitive layers. In the present specification, "the layer contains a merocyanine dye and a base precursor" includes a case where there are a plurality of "layers", that is, a case where a plurality of layers separately contain a merocyanine dye and a base precursor.

As a method of adding the merocyanine dye to the non-photosensitive layer, a method of adding a solution, an emulsion, a solid fine particle dispersion or a polymer-impregnated substance to the coating solution for the non-photosensitive layer can be adopted. Further, a dye may be added to the non-photosensitive layer using a polymer mordant. These addition methods are the same as the method of adding a dye to an ordinary photothermographic material.
For the latex used in the polymer impregnated product, see US Pat. No. 4,199,363 and West German Patent Publication 25141274.
No. 2,541,230, European Patent Publication No. 029104, and JP-B-53-41091. Regarding an emulsification method of adding a dye to a solution in which a polymer is dissolved, International Publication No. 88/0072
No. 3 describes it. The amount of the dye to be added is determined according to the intended action of the dye. Generally, the optical density (absorbance) measured at the target wavelength is used in an amount exceeding 0.1. The optical density is preferably from 0.2 to 2. The amount of the dye used to obtain such an optical density is generally about 0.001 to 1 g / m ² . When the dye is decolorized according to the present invention, the optical density is 0.1%.
It can be reduced to: Two or more dyes,
It may be used in combination with a thermal decoloring type recording material or a photothermographic material. Similarly, two or more base precursors may be used in combination. Hereinafter, the photothermographic material will be further described.

The photothermographic material is preferably of a monosheet type (a type capable of forming an image on the photothermographic material without using another sheet such as an image receiving material). The present invention is particularly effective for a photothermographic material for near infrared exposure. The photothermographic material has a photosensitive layer containing silver halide (a catalytically active amount of a photocatalyst) and a reducing agent, and a non-photosensitive layer. The photosensitive layer further includes a binder (generally a synthetic polymer), an organic silver salt (a reducible silver source), a hydrazine compound (a super-high contrast agent), and a color tone adjuster (which controls the color tone of silver).
It is preferable to include A plurality of photosensitive layers may be provided. For example, a high-sensitivity photosensitive layer and a low-sensitivity photosensitive layer can be provided on a photothermographic material for the purpose of adjusting the gradation. The order of arrangement of the high-sensitivity photosensitive layer and the low-sensitivity photosensitive layer may be such that the low-sensitivity photosensitive layer is disposed below (the support side) or the high-sensitivity photosensitive layer is disposed below. The non-photosensitive layer may be provided as another functional layer such as a surface protective layer in addition to the above-mentioned dye-containing layer, that is, the filter layer and the antihalation layer.

As a support of the photothermographic material, paper, polyethylene-coated paper, polypropylene-coated paper, parchment, cloth, metal (eg, aluminum, copper, magnesium, zinc) sheet or thin film, glass, Glass and plastic films coated with a metal (eg, chromium alloy, steel, silver, gold, platinum) are used. Examples of the plastic used for the support include polyalkyl methacrylate (eg, polymethyl methacrylate), polyester (eg, polyethylene terephthalate), polyvinyl acetal, polyamide (eg, nylon), and cellulose ester (eg, cellulose nitrate, cellulose). Acetate, cellulose acetate propionate, cellulose acetate butyrate). The support may be coated with a polymer. Examples of polymers include polyvinylidene chloride, acrylic acid based polymers (eg,
Polyacrylonitrile, methyl acrylate), polymers of unsaturated dicarboxylic acids (eg, itaconic acid, acrylic acid), carboxymethylcellulose and polyacrylamide. Copolymers may be used. Instead of coating with a polymer, an undercoat layer containing a polymer may be provided.

As silver halide, any of silver bromide, silver iodide, silver chloride, silver chlorobromide, silver iodobromide and silver chloroiodobromide can be used. However, it preferably contains silver iodide. The added amount of silver halide is 0.03
To 0.6 g / m ² , more preferably 0.05 to 0.4 g / m ² , and more preferably 0.1 to 0.4 g / m ^2.
Most preferably, it is from 0.4 to 0.4 g / m ² . Silver halide is generally prepared as a silver halide emulsion by reacting silver nitrate with a soluble halide salt. However, it may be prepared by reacting silver soap with halogen ions and converting the soap portion of silver soap into halogen. Further, halogen ions may be added during the formation of the silver soap. Phenidone, hydroquinones, catechol and hindered phenol are preferred as reducing agents. As for the reducing agent, U.S. Pat. Nos. 3,770,448, 3,773,512 and 3,938,
Nos. 63 and 4460681, and Research Disclosure Magazine 17
Nos. 029 and 29963.

Examples of the reducing agent include aminohydroxycycloalkenones (eg, 2-hydroxy-piperidino-
2-cyclohexenone), N-hydroxyurea derivatives (eg, Np-methylphenyl-N-hydroxyurea), hydrazones of aldehydes or ketones (eg, anthracenaldehyde phenylhydrazone), phosphoramidophenols, phosphates Amidoanilines,
Polyhydroxybenzenes (eg, hydroquinone, t-butyl-hydroquinone, isopropylhydroquinone, 2,
5-dihydroxy-phenylmethylsulfone), sulfohydroxamic acids (eg, benzenesulfohydroxamic acid), sulfonamidoanilines (eg, 4- (N-methanesulfonamido) aniline), 2-tetrazolylthiohydroquinones (eg, 2-methyl-5- (1-phenyl-5-tetrazolylthio) hydroquinone), tetrahydroquinoxalines (eg, 1,2,3,4-tetrahydroquinoxaline), amidooxines, azines (eg, aryl aryl carboxylate) Hydrazides) and ascorbic acid, polyhydroxybenzene and hydroxylamine, reductone, hydrazine, hydroxamic acids, azines and sulfonamidephenols, α-cyanophenylacetic acid derivatives, bis-β- Naphtho , A combination of a 1,3-dihydroxybenzene derivative, 5-pyrazolones, sulfonamidophenols, and 2-phenylindane-1,3-
Dione, chroman, 1,4-dihydropyridines (eg,
2,6-dimethoxy-3,5-dicarbethoxy-1,
4-dihydropyridine), bisphenols (eg, bis (2-hydroxy-3-t-butyl-5-methylphenyl) methane, bis (6-hydroxy-m-tri) mesitol, 2,2-bis (4-hydroxy -3-methylphenyl) propane, 4,4-ethylidene-bis (2-t-
Butyl-6-methyl) phenol), UV-sensitive ascorbic acid derivatives and 3-pyrazolidones.

An ester of an aminoreductone (eg, piperidinohexose reductone monoacetate) which functions as a precursor of the reducing agent may be used as the reducing agent. Particularly preferred reducing agents are hindered phenols. It is preferable that the photosensitive layer and the non-photosensitive layer contain a binder. Generally, a colorless transparent or translucent polymer is used as the binder. Natural or semi-synthetic polymers (eg, gelatin, gum arabic, hydroxyethylcellulose, cellulose ester, casein, starch) can also be used, but synthetic polymers are preferred over natural or semi-synthetic polymers in view of heat resistance. However, even if a cellulose ester (eg, acetate, cellulose acetate butyrate) is a semi-synthetic polymer, it has relatively high heat resistance and is preferably used as a binder for a photothermographic material.

Examples of synthetic polymers include polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, polymethyl methacrylate, polyvinyl chloride, polymethacrylic acid, styrene / maleic anhydride copolymer, styrene /
Includes acrylonitrile copolymer, styrene / butadiene copolymer, polyvinyl acetal (eg, polyvinyl formal, polyvinyl butyral), polyester, polyurethane, phenoxy resin, polyvinylidene chloride, polyepoxide, polycarbonate, polyvinyl acetate, and polyamide. Hydrophobic polymers are preferred over hydrophilic polymers. Thus, styrene / acrylonitrile copolymer, styrene / butadiene copolymer, polyvinyl acetal, polyester, polyurethane, loose acetate butyrate, polyacrylic acid,
Polymethyl methacrylate, polyvinyl chloride and polyurethane are preferred, and styrene / butadiene copolymer and polyvinyl acetal are more preferred. The binder is used after being dissolved or emulsified in a solvent (water or organic solvent) of the coating solution for the photosensitive layer or the non-photosensitive layer. When emulsifying the binder in the coating solution, the emulsion of the binder may be mixed with the coating solution.

The amount of the binder used in the layer containing the dye is preferably adjusted so that the amount of the dye to be applied is 0.1 to 60% by weight of the binder. The dye is preferably 0.2 to 30% by weight of the binder,
Most preferably, it is 0.5 to 10% by weight. The photosensitive layer or the non-photosensitive layer preferably further contains an organic silver salt. The organic acid forming the silver salt is preferably a long-chain fatty acid. The fatty acid preferably has 10 to 30 carbon atoms, and more preferably 15 to 25 carbon atoms. An organic silver salt complex may be used. The ligand of the complex preferably has a total stability constant for silver ions in the range of 4.0 to 10.0. Regarding organic silver salts, Research Disclosure 17
Nos. 029 and 29963.

Examples of organic silver salts include silver salts of fatty acids (eg, gallic acid, oxalic acid, behenic acid, stearic acid, palmitic acid, lauric acid), carboxyalkylthioureas (eg, 1- (3-carboxypropyl) ) Thiourea, 1-
Silver salt of (3-carboxypropyl) -3,3-dimethylthiourea), silver complex of polymer reaction product of aldehyde (eg, formaldehyde, acetaldehyde, butyraldehyde) and hydroxy-substituted aromatic carboxylic acid, aromatic carboxylic acid Silver salts of (e.g., salicylic acid, benzoic acid, 3,5-dihydroxybenzoic acid, 5,5-thiodisalicylic acid), thioenes (e.g., 3- (2-carboxyethyl)-
Silver salt or silver complex of 4-hydroxymethyl-4-thiazoline-2-thioene, 3-carboxymethyl-4-thiazoline-2-thioene), nitrogen acid (eg, imidazole, pyrazole, urazole, 1,2,4- Thiazole, 1H-tetrazole, 3-amino-5-benzylthio-1,2,4-triazole, benzotriazole)
Or silver complexes of saccharin, silver salts of 5-chlorosalicylaldoxime and silver salts of mercaptides. Silver behenate is most preferred. Organic silver salts
The silver content is preferably 3 g / m ² or less, preferably ² g / m ² or less.
It is more preferable to use g / m ² or less.

The photosensitive layer or the non-photosensitive layer preferably further contains a super-high contrast agent. When a photothermographic material is used in the field of photographic printing, it is important to reproduce a continuous tone image or a line image using halftone dots. By using a super-high contrast agent, the reproducibility of halftone images and line images can be improved. As the super-high contrast agent, a hydrazine compound, a quaternary ammonium compound or an acrylonitrile compound (described in US Pat. No. 5,545,515) is used. Hydrazine compounds are particularly preferred ultrahigh contrast agents. Hydrazine compounds include compounds hydrazine (H ₂ N-NH ₂₎ and less of the hydrogen atom was replaced one. As the substituent, an aliphatic group, an aromatic group or a heterocyclic group is directly bonded to a hydrazine nitrogen atom, or an aliphatic group, an aromatic group or a heterocyclic group is bonded to a hydrazine nitrogen atom via a linking group. . Examples of the linking group include -CO-, -CS-, -S
O ₂ -, - POR- (R is an aliphatic group, an aromatic group or a heterocyclic group), - it includes CNH- and combinations thereof. For hydrazine compounds, see US Pat.
738, 5496695, 5512411,
Nos. 5,536,622, JP-B-6-77138
No. 6-93082, JP-A-6-230497,
6-289520, 6-313951, 7-
No. 5610, No. 7-77783, No. 7-104426
There is a description in each gazette of the issue.

The hydrazine compound can be dissolved in a suitable organic solvent and added to the photosensitive layer coating solution. Examples of organic solvents include alcohols (eg, methanol, ethanol, propanol, fluorinated alcohols), ketones (eg, acetone, methyl ethyl ketone), dimethylformamide, dimethyl sulfoxide, and methyl cellosolve. In addition, hydrazine compound is oily (auxiliary)
A solution dissolved in a solvent may be emulsified in a coating solution. Examples of oily (auxiliary) solvents include dibutyl phthalate, tricresyl phosphate, glyceryl triacetate, diethyl phthalate, ethyl acetate and cyclohexanone. Further, a solid dispersion of a hydrazine compound may be added to the coating solution. The dispersion of the hydrazine compound is
It can be carried out using a known dispersing machine such as a ball mill, a colloid mill, a Menton-Gauling, a microfluidizer and an ultrasonic dispersing machine. The added amount of the super-high contrast agent is preferably 1 × 10 ^{-6 to} 1 × 10 ^-2 mol, and more preferably 1 × 10 ^{-5 to} 5 × 10 ^-3 mol, per mol of silver halide. More preferably, 2 × 10 ^{-5 to} 5 × 10
Most preferably, it is ^-3 mol. In addition to the super-high contrast agent, a high-contrast accelerator may be used. Examples of the high contrast accelerator include amine compounds (described in US Pat. No. 5,545,505), hydroxamic acids (described in US Pat. No. 5,545,507), and acrylonitriles (US Pat. No. 5,554,550).
No. 7) and a hydrazine compound (US Pat.
558983). The photosensitive layer or the non-photosensitive layer preferably further contains a color tone adjuster. The color tone adjusting agent is described in Research Disclosure No. 17029.

Examples of color tone adjusting agents include imides (eg, phthalimide), cyclic imides (eg, succinimide), pyrazolin-5-ones (eg, 3-phenyl-2-pyrazolin-5-one, -Phenylurazole), quinazolinones (eg, quinazoline, 2,4-thiazolidinedione), naphthalimides (eg, N-hydroxy-1,
8-naphthalimide), a cobalt complex (eg, hexamine trifluoroacetate of cobalt), mercaptans (eg, 3-mercapto-1,2,4-triazole), N- (aminomethyl) aryldicarboximides (eg, N- (dimethylaminomethyl) phthalimide), blocked pyrazoles (eg, N, N′hexamethylene-1-carbamoyl-3,5-dimethylpyrazole), isothiuronium derivatives (eg, 1,8- ( Combination of 3,6-dioxaoctane) bis (isothiuronium trifluoroacetate) with a photobleach (eg, 2- (tribromomethylsulfonyl) benzothiazole), cyanine dye (eg, 3-ethyl-5-) ((3-ethyl-2-benzothiazolinylidene))-1-methyl Chileden)
-2-azo-2,4-oxazolidinedione (oxazolid
inedione)), phthalazinone compounds and metal salts thereof (eg, phthalazinone, 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxyphthalazinone, 2,3-dihydro-1,4- Phthalazinedione, 8-methylphthalazino), a combination of a phthalazinone compound with a sulfinic acid derivative (eg, sodium benzenesulfinate), a combination of a phthalazinone compound with a sulfonic acid derivative (eg, sodium p-toluenesulfonate), phthalazine and A combination with phthalic acid, phthalazine or a phthalazine adduct and a dicarboxylic acid (preferably o-phenylene acid) or an anhydride thereof (eg, maleic anhydride, phthalic acid, 2,3-naphthalenedicarboxylic acid, phthalic anhydride; 4-methylphthalic acid, 4-nitrophthalic acid, tetra Chlorophthalic anhydride), quinazolinediones, benzoxazine, naltoxazine derivatives, benzoxazine-
2,4-diones (eg, 1,3-benzoxazine-
2,4-dione), pyrimidines, asymmetric triazines (eg, 2,4-dihydroxypyrimidine), tetraazapentalene derivatives (eg, 3,6-dimerocapto-
1,4-diphenyl-1H, 4H-2,3a, 5,6a
-Tetraazapentalene) and phthalazine. Phthalazine is particularly preferred.

An antifoggant may be added to the photosensitive layer or the non-photosensitive layer (preferably the photosensitive layer). As an antifoggant, a mercury compound (described in US Pat. No. 3,589,903) is more preferable than a non-mercury compound (US Pat.
No. 946, No. 4546075, No. 44452885,
Nos. 4,756,999 and 5,028,523, UK Patent Application Nos. 92221383.4 and 93001777.7.
Nos. 9311790.1 and JP-A-59-1790.1.
57234). Particularly preferred antifoggants include halogens (F, Cl, Br,
I) A heterocyclic compound having a substituted methyl group.

Silver halide is generally used after spectral sensitization. Regarding spectral sensitizing dyes, see JP-A-60-1403.
No. 35, No. 63-159,841 and No. 63-23143
No. 7, 63-259,651 and 63-304242
Nos. 63-15245 and U.S. Pat.
Nos. 414, 474,455 and 474,966,
Nos. 4,751,175 and 4,835,096. In the photothermographic material, a surfactant,
Antioxidants, stabilizers, plasticizers, ultraviolet absorbers or coating aids may be added. Various additives are added to either the photosensitive layer or the non-photosensitive layer. The photothermographic material forms an image by heating after image exposure.
By this heat development, a black silver image is formed. The image exposure is preferably performed using a laser. The heating temperature of the thermal development is preferably from 80 to 250 ° C, more preferably from 100 to 200 ° C.
The heating time is generally between 1 second and 2 minutes.

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Next, the present invention will be described in more detail with reference to examples. Example 1 (Decolorization reaction of merocyanine dye) 1 g of merocyanine dye (2) was dissolved in 10 ml of dimethyl sulfoxide,
0.7 ml of triethylamine was added, and the mixture was heated at 120 ° C. for 1 minute. Immediately after the start of heating, the blue color of the solution disappeared, and the solution became a pale yellow solution. The solution was allowed to cool, and the precipitated white crystals were separated by filtration. This compound is a neutral compound having high hydrophobicity, a compound having a molecular weight of 538, in which one counter anion and one proton atom have been removed from the dye (2) by mass spectrum, and 1 H-NMR
The spectrum revealed that the compound was ring-closed and decolorized in the molecule.

Also, instead of triethylamine, 1,8
When a decolorization reaction was performed using diazabicyclo [5,4,0] -7-undecene, guanidine and sodium hydroxide as bases, a ring-closed decolored compound was formed in the molecule in each case. Was confirmed. Next, without adding a base, the merocyanine dye (2)
Was dissolved in deuterated dimethylsulfoxide-d6 to prepare a solution. This solution was heated at 160 ° C. for 2 hours
The presence or absence of a reaction was observed by 1 H-NMR measurement, but no reaction was confirmed. When no base was present, it was found to be extremely stable. Furthermore, in place of the merocyanine dye (2), the merocyanine dye (1),
(3), (9), (11), (13), and (24)
When the decolorization reaction was carried out using each of the above, it was confirmed that, in each case, similarly to the merocyanine dye (2), a compound which was ring-closed and decolored in the molecule was formed.

Example 2 (Decoloring Reaction of Various Dyes) A base precursor (BP-41) was added to a dimethylformamide solution (1 × 10 ⁻⁵ mol / dm ³ ) of a dye shown in Table 1 below at a concentration of 1 × 10 ^{5 -4} mol / dm ³
And heated at 110 ° C. for 30 seconds. The absorbance of each dye in the first absorption band (λmax) was measured to determine the residual ratio of the dye. Table 1 shows the above results.

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[Table 1]

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Example 3 (Preparation of solid dispersion of base precursor) 3% by weight of polyvinyl alcohol was placed in a 300 ml dispersion container.
52.5 g of aqueous solution, cellogen 6A (manufactured by Shin-Etsu Chemical Co., Ltd.)
52.5 g of a 3% by weight aqueous solution of a base precursor (BP
-41) 40 g and 150 ml of glass beads having a diameter of 0.5 to 0.75 mm were put therein. 30 using Dynomill
Disperse at 00 rpm for 30 minutes, and adjust the pH to 6 with 2N sulfuric acid.
By adjusting to 5, a solid dispersion of a base precursor having a particle size of about 1 μm was obtained.

(Preparation of fine particle dispersion of dye) 1.6 g of merocyanine dye (1) was dissolved in 30 g of ethyl acetate.
Separately, a 20% by weight aqueous solution of polyvinyl alcohol 31
g, 21 g of water and 10 g of a 5% by weight aqueous solution of sodium dodecylbenzenesulfonate were mixed and placed in a 200 ml homogenizer cup. A solution of the dye was added thereto, followed by stirring at 10,000 rpm for 5 minutes to obtain an emulsion of the dye. The emulsion was stirred at 50 ° C. for 2 hours to remove ethyl acetate, and the same amount of water as the evaporated amount was added to obtain a fine particle dispersion of a dye having a particle size of about 0.4 μm.

(Preparation of Thermal Decolorable Recording Material) 0.5 g of water and a 20% by weight aqueous solution of polyvinyl alcohol were added to 5.1 g of the fine particle dispersion of the above dye, and mixed. 2 g of a solid dispersion of a base precursor was added to the mixture, and the mixture was further mixed to prepare a coating solution for the thermal decoloring recording layer. Thickness 100
10. A coating amount of a coating solution on a polyethylene terephthalate film (support) provided with a μm gelatin undercoat layer.
It was applied at 5 g / m ² and dried. 4 g of a 10 wt% aqueous solution of polyvinyl alcohol, 1 g of a 2 wt% aqueous solution of poly (n = 10) ethylene glycol dodecyl ether (surfactant), 0.5 g of a 20 wt% aqueous dispersion of zinc stearate having a particle size of 0.2 μm And 4.8 g of water were mixed to prepare a coating solution for the protective layer. This coating solution was applied onto the thermal decolorable recording layer at a coating amount of 17.5 g / m ² and dried to prepare a thermal decolorable recording material.

(Formation of Thermal Decolorable Image) The thermal decolorizable recording material was imagewise heated in eight gradation steps using a thermal imager (FTI210, manufactured by Fuji Photo Film Co., Ltd.). A negative was obtained in which the high-energy part became colorless. When the heat-decolorable recording material was stored at 40 ° C. and a relative humidity of 80% for 3 days, no decoloration of the heat-decolorable recording layer was observed. When imagewise heating was performed in the same manner as described above using the heat-decolorable recording material after storage for 3 days, a clear negative image similar to that immediately after production was obtained.

Example 4 (Preparation of Solid Precursor Dispersion of Base Precursor) 5.12 g of base precursor (BP-7) and 1.02 g of polyvinyl alcohol were mixed with 43.5 g of water. / 16G sand grinder mill, manufactured by Amimex Co., Ltd.) to obtain a dispersion of solid fine particles of a base precursor.

(Preparation of Emulsion of Dye) 0.8 g of merocyanine dye (1) was dissolved in 35 g of ethyl acetate to obtain an organic phase. The organic phase was mixed with 84 g of a 6% by weight aqueous solution of polyvinyl alcohol and emulsified at room temperature to give an average particle size of 1.
An emulsion of a dye of 2 μm was obtained.

(Preparation of antihalation layer coating liquid) 4 g of a solid fine particle dispersion of a base precursor and 4 g of a dye emulsion were mixed with a 4% by weight aqueous solution
In addition, the mixture was stirred to prepare an antihalation layer coating solution.

(Formation of Antihalation Layer) Thickness of 17
A moisture-proof undercoat layer containing vinylidene chloride was provided on one surface of a 5 μm polyethylene terephthalate film (support). On the other side of the support, a gelatin subbing layer was provided. An antihalation layer coating solution is applied on the moisture-proof undercoat layer so that the dry solid content is 2 g / m ² .
After drying, an antihalation layer was formed.

(Preparation of silver halide emulsion) 700 ml of water
22g phthalated gelatin and 30mg potassium bromide
Was dissolved. After adjusting the solution to pH 5.0 at 35 ° C., 159 ml of an aqueous solution containing 18.6 g of silver nitrate and 0.9 g of ammonium nitrate, and an aqueous solution containing potassium bromide and potassium iodide in a molar ratio of 92: 8, pAg
While maintaining at 7.7, it was added over 10 minutes by the controlled double jet method. Then, 55.4 g of silver nitrate
And 476 ml of an aqueous solution containing 2 g of ammonium nitrate and an aqueous solution containing 10 μmol / L of dipotassium hexachloroiridate and 1 mol / L of potassium bromide,
While maintaining the pAg at 7.7, it was added over 30 minutes by the controlled double jet method. Further, 1 g of 4-hydroxy-6-methyl 1,3,3a, 7-tetrazaindene was added, and the pH was lowered to cause coagulation and sedimentation, followed by desalting treatment. Thereafter, 0.1 g of phenoxyethanol was added,
The pH was adjusted to 5.9 and pAg to 8.2 to complete the formation of silver iodobromide grains. The iodine content of the particles was 8 mol% in the core portion and 2 mol% on the average of the whole particles. The average particle diameter was 0.05 μm, the variation coefficient of the projected area was 8%, and (10
0) Cubic particles having an area ratio of 88%. The temperature of the silver halide grains was raised to 60 ° C., and 85 μmol of sodium thiosulfate, 11 μmol of 2,3,4,5,6-pentafluorophenyldiphenylphosphine selenide per mol of silver, and 15 μmol of the following tellurium compound , 3.5μ chloroauric acid
Moles and 270 μmoles of thiocyanic acid,
After ripening for 30 minutes, the mixture was rapidly cooled to 30 ° C. to obtain a silver halide emulsion.

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(Preparation of Organic Silver Salt Emulsion) Stearic acid 7
g, arachidic acid 4 g and behenic acid 36 g in distilled water 8
Added to 50 ml. While vigorously stirring the mixture at 90 ° C., 187 ml of a 1N aqueous sodium hydroxide solution was added,
The reaction was performed for 60 minutes. After adding 65 ml of 1N nitric acid,
The temperature was lowered to 50 ° C. Then, with more vigorous stirring,
0.62 g of N-bromosuccinimide was added, and 10 minutes later, the above-mentioned silver halide emulsion was added to the emulsion.
It was added to 2 mmol. Furthermore, silver nitrate 21
125 ml of an aqueous solution of N-bromosuccinimide was added over 100 seconds, and the mixture was continuously stirred for 10 minutes.
62 g were added and left for another 10 minutes. Thereafter, the solid content was separated by suction filtration, and the solid content was filtered to a conductivity of 30%.
Washed with water until it reached μS / cm. To the solid content thus obtained, 150 g of a 0.6% by weight solution of polyvinyl acetate in butyl acetate was added and stirred. After completion of the stirring, the mixture was allowed to stand to separate the oil phase and the aqueous phase, and the aqueous phase containing salts was removed to obtain an oil phase. Next, 2.5 g of polyvinyl butyral (Denka butyral # 3000-K, manufactured by Denki Kagaku Kogyo KK) was added to the oil phase.
80% by weight of a 2-butanone solution was added and stirred. 0.1 mmol of pyridinium perbromide and 0.15 mol of calcium bromide dihydrate were added together with 0.7 g of methanol. Further, 200 g of 2-butanone and 59 g of polyvinyl butyral (BUTVAR-76, manufactured by Mondant Co.) were added, dispersed with a homogenizer, and an organic silver salt emulsion (average minor axis of needle-like particles: 0.04 μm, average major axis: 1 μm, (Coefficient of variation 30%).

(Preparation of Coating Solution for Photosensitive Layer) The following components were added to the organic silver salt emulsion at 25 ° C. twice in the primary addition and the secondary addition so as to be in the following amounts per mole of silver. Was added with stirring to prepare a photosensitive layer coating solution.

Photosensitive layer coating liquid component (primary addition) Sodium phenylthiosulfonate 10 mg Dye below 80 mg 2-mercapto-5-methylbenzimidazole 2 g 4-chlorobenzophenone-2-carboxylic acid 21.5 g 2-butanone 580 g dimethyl 220 g formamide

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Photosensitive layer coating liquid component (secondary addition) 5-tribromomethylsulfonyl-2-methylthiadiazole 8 g 2-tribromomethylsulfonylbenzothiazole 6 g 4,6-ditrichloromethyl-2-phenyltriazine 5 g Disulfide compound 2g 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane 155g Fluorosurfactant (Megafax F-176P, Dainippon Ink and Chemicals, Inc.) 1.1 g 2-butanone 590 g methyl isobutyl ketone 10 g

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(Preparation of Coating Solution for Emulsion Surface Protective Layer) 75 g of cellulose acetate butyrate (CAB171-15S, manufactured by Eastman Chemical Co., Ltd.), 5.7 g of 2-methylphthalic acid, 1.5 g of tetrachlorophthalic anhydride, 12.5 g of phthalazine, 5.1 g of tetrachlorophthalic acid, 0.3 g of a fluorine-based surfactant (Megafax F-176P, manufactured by Dainippon Ink and Chemicals, Inc.), spherical silica particles having an average particle size of 3 μm (Sil) 2 g of Dex H31, Dokai Chemical Co., Ltd. and polyisocyanate (Sumid)
urN3500, manufactured by Sumitomo Bayer Urethane Co., Ltd.)
It was dissolved in 3070 g of 2-butanone and 30 g of ethyl acetate to prepare an emulsion surface protective layer coating solution.

(Preparation of Coating Solution for Back Surface Protective Layer) Gelatin 10 g, polymethyl methacrylate particles (average particle size: 7)
μm) 0.6 g, sodium dodecylbenzenesulfonate 0.4 g and a silicone compound (X-22-280)
9, 0.9 g of Shin-Etsu Silicone Co., Ltd.) was dissolved in 500 g of water to prepare a back surface protective layer coating solution.

(Preparation of Photothermographic Material 101) On the surface of the support opposite to the antihalation layer, a coating solution for a photosensitive layer was applied so that the coated silver amount was 2.3 g / m ² . . Next, a coating liquid for the back surface protective layer was applied on the antihalation layer at an application amount of a dry thickness of 0.9 μm. Further, an emulsion surface protective layer coating solution was coated on the photosensitive layer at a coating amount of 2 μm in dry thickness. Thus, a photothermographic material 101 was prepared.

(Preparation of Photothermographic Materials 102 to 108)
In preparing the photothermographic material 101, the merocyanine dye (2), the merocyanine dye (3), the merocyanine dye (23), the comparative dye 1, the comparative dye 2 and the comparative dye 3 were used instead of the merocyanine dye (1). Except that the same amount was used, the photothermographic materials 102 to 107 were prepared in the same manner.
It was created. A photothermographic material 108 was prepared in the same manner as the photothermographic material 101 except that the merocyanine dye (1) was not added.

(Evaluation of Photographic Performance) After exposing the photothermographic material with a 635 nm semiconductor laser photometer, the photothermographic material was processed (heat development) at 120 ° C. for 15 seconds, and the obtained image was measured with a densitometer. The measurement results were evaluated based on the minimum density (Dmin) corresponding to fog and the sensitivity (reciprocal of the ratio of the exposure amount giving a density higher than Dmin by 1.0). Table 2 shows the results. In Table 2, the sensitivities are shown as relative sensitivities with the sensitivity of the photothermographic material 101 as 100.

(Evaluation of Sharpness) The photothermographic material was exposed to a square having a side of 1 cm using a 635 nm semiconductor laser photometer. The exposure amount x at which the density becomes 2.5 and the exposure amount y at which the density becomes 0.5 were obtained. Next, short side 100 μm, long side 1
Exposure was performed alternately at an exposure amount x and an exposure amount y such that the long sides of the rectangular rectangle of cm were in contact with each other, and the maximum density and the minimum density of the exposed area were measured with a microdensitometer. The value obtained by dividing the difference between the highest density and the lowest density by 2 was evaluated as sharpness. Table 2 shows the results.

(Evaluation of Storage Stability) Photothermographic Material 101
To 108 at high temperature (50 ° C.) and high humidity (80% relative humidity).
%) For 3 days, and the absorbance at 690 nm was measured before and after storage. The absorbance (Db) of the photosensitive materials 101 to 107 before storage, the absorbance after storage (Da), and the absorbance of the photosensitive material 108 without dye after storage (D
From the measurement result of 0), the photosensitive materials 101 to 1 were obtained by the following formulas.
07 was determined and used as an index of storage stability. The photosensitive material 108 has a thickness of 690 nm before and after storage.
There was no change in absorbance at. 100 × (Da−D0) / (Db−D0) The closer the value defined by the above formula to 100, the higher the storage stability of the dye. Table 2 shows the results.

[0148]

[Table 2]

[0149]

According to the present invention, when a specific merocyanine compound is used as a coloring dye of a photothermographic material, an excellent image with little residual color can be formed. In addition, a heat-decolorable recording material can be prepared using a specific merocyanine compound. Further, in the method for decolorizing a merocyanine dye of the present invention, a relatively stable colored merocyanine dye can be rapidly and substantially decolored by an intramolecular ring closing mechanism.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Kaji Yabuki 210 Nakanakanuma, Minamiashigara-shi, Kanagawa Prefecture Fuji Photo Film F-term (reference) 2H026 AA07 AA21 BB50 DD42 DD56 2H123 AB00 AB03 AB23 AB28 BA00 BA64 BB00 BB02 BB04 BB20 CB00 CB03 4H056 CA03 CC08 CE03 CE06 CE07 DD03 DD04 DD06 DD07 DD19 DD23 DD28 DD29 DD30 FA05

Claims (4)

[Claims] 1. A photothermographic material comprising a support, a photosensitive layer containing silver halide and a reducing agent, and a non-photosensitive layer, wherein at least one non-photosensitive layer has the following formula (I)
A photothermographic material comprising a merocyanine dye represented by the formula: and a base precursor. Embedded image In the formula, R ¹ is a hydrogen atom, an aliphatic group, an aromatic group, -NR
₂₁ R ₂₆ , -OR ₂₁ or -SR ₂₁ , and R ₂₁ and R
₂₆ is each independently a hydrogen atom, an aliphatic group or an aromatic group, or R ₂₁ and R ₂₆ are combined to form a nitrogen-containing heterocyclic ring; R ² is a hydrogen atom, an aliphatic group or L ¹ and L ² are each independently an optionally substituted methine, which is substituted with a methine substituent to form an unsaturated aliphatic ring or an unsaturated heterocyclic ring; Z ¹ is an atomic group forming a 5- or 6-membered nitrogen-containing heterocyclic ring, and the nitrogen-containing heterocyclic ring may be condensed with an aromatic ring; The ring may have a substituent; Z ² is an atomic group forming a 5- or 6-membered ring; and n is 1, 2, 3, or 4. 2. A recording material having a recording layer on a support, wherein at least one recording layer contains a merocyanine dye represented by the following formula (I) and a base precursor, and the merocyanine dye is a molecule or solid fine particles. A recording material, wherein the recording material is dispersed in a recording layer in the state of (1). Embedded image In the formula, R ¹ is a hydrogen atom, an aliphatic group, an aromatic group, -NR
₂₁ R ₂₆ , -OR ₂₁ or -SR ₂₁ , and R ₂₁ and R
₂₆ is each independently a hydrogen atom, an aliphatic group or an aromatic group, or R ₂₁ and R ₂₆ are combined to form a nitrogen-containing heterocyclic ring; R ² is a hydrogen atom, an aliphatic group or L ¹ and L ² are each independently an optionally substituted methine, which is substituted with a methine substituent to form an unsaturated aliphatic ring or an unsaturated heterocyclic ring; Z ¹ is an atomic group forming a 5- or 6-membered nitrogen-containing heterocyclic ring, and the nitrogen-containing heterocyclic ring may be condensed with an aromatic ring; The ring may have a substituent; Z ² is an atomic group forming a 5- or 6-membered ring; and n is 1, 2, 3, or 4. 3. A method for decolorizing a merocyanine dye represented by the following formula (I) by decoloring the merocyanine dye by applying a base under heating conditions. Embedded image In the formula, R ¹ is a hydrogen atom, an aliphatic group, an aromatic group, -NR
₂₁ R ₂₆ , -OR ₂₁ or -SR ₂₁ , and R ₂₁ and R
₂₆ is each independently a hydrogen atom, an aliphatic group or an aromatic group, or R ₂₁ and R ₂₆ are combined to form a nitrogen-containing heterocyclic ring; R ² is a hydrogen atom, an aliphatic group or L ¹ and L ² are each independently an optionally substituted methine, which is substituted with a methine substituent to form an unsaturated aliphatic ring or an unsaturated heterocyclic ring; Z ¹ is an atomic group forming a 5- or 6-membered nitrogen-containing heterocyclic ring, and the nitrogen-containing heterocyclic ring may be condensed with an aromatic ring; The ring may have a substituent; Z ² is an atomic group forming a 5- or 6-membered ring; and n is 1, 2, 3, or 4. 4. The method for decolorizing a merocyanine dye according to claim 3, wherein the heating causes the color of the dye to be decolorized by an intramolecular ring closure reaction.