JP2002169248A - Heat developable photosensitive material, recording material and method for decoloring dye - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat developable photosensitive material containing a heat decolorable dye excellent in decolorability and shelf stability, a heat decolorable recording material and a method for decoloring the dye. SOLUTION: A styryl dye forming an intramolecular closed circular decolored body by the action of a base under a heating condition is used as the heat decolorable dye.

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 decoloring a 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 them is a problem of dye decolorization. It is common to add a dye to a photographic light-sensitive material for the purpose of a filter, prevention of halation and prevention of 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.

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. To solve the problem that the 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, US Pat. No. 5,135,842 discloses a method of decolorizing a polymethine dye having a specific structure by heating. U.S. Pat. Nos. 5,314,795 and 532
Nos. 4627 and 5384237 each disclose a method of decoloring a polymethine dye by heating using a carbanion generator.

[0005]

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.

An object of the present invention is to provide a photothermographic material which contains an excellent thermo-decolorable dye in a non-photosensitive layer without the above-mentioned problems. 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 a dye which is stable at room temperature by heating.

[0007]

The object of the present invention is attained by the following photothermographic materials (1), recording materials (2) and dye erasing methods (3) and (4). Was.

(1) A photothermographic material having a support, a photosensitive layer containing silver halide and a reducing agent, and a non-photosensitive layer, wherein at least one of the photosensitive layer and the non-photosensitive layer is as follows: A photothermographic material comprising a dye represented by the formula (1) and a base precursor.

[0009]

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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 a substituted or unsubstituted methine, and the substituents of methine are bonded to each other to form an unsaturated aliphatic ring or an unsaturated heterocyclic ring; A represents an aromatic heterocyclic ring or a general formula (2); R ³ represents an aliphatic group, an aromatic group, or a heterocyclic group. Z ¹ is an atomic group necessary to complete a 5- or 6-membered nitrogen-containing heterocyclic ring, and the nitrogen-containing heterocyclic ring may be condensed with an aromatic ring. The fused ring may have a substituent; V ¹ represents a monovalent substituent; n is 1, 2, 3, or 4; and m is an integer from 0 to 4.

(2) A recording material having a recording layer on a support, wherein at least one recording layer contains a dye represented by the following formula (1) and a base precursor, and the dye is a molecule or solid fine particle. A recording material which is dispersed in a recording layer in a state.

[0012]

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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 a substituted or unsubstituted methine, and the substituents of methine are bonded to each other to form an unsaturated aliphatic ring or an unsaturated heterocyclic ring; A represents an aromatic heterocyclic ring or a general formula (2); R ³ represents an aliphatic group, an aromatic group, or a heterocyclic group. Z ¹ is an atomic group necessary to complete a 5- or 6-membered nitrogen-containing heterocyclic ring, and the nitrogen-containing heterocyclic ring may be condensed with an aromatic ring. The fused ring may have a substituent; V ¹ represents a monovalent substituent; n is 1, 2, 3, or 4; and m is an integer from 0 to 4.

(3) A dye represented by the following formula (1):
A method for decoloring a dye, which is decolorized by a base acting under heating conditions.

[0015]

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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 a substituted or unsubstituted methine, and the substituents of methine are bonded to each other to form an unsaturated aliphatic ring or an unsaturated heterocyclic ring; A represents an aromatic heterocyclic ring or a general formula (2); R ³ represents an aliphatic group, an aromatic group, or a heterocyclic group. Z ¹ is an atomic group necessary to complete a 5- or 6-membered nitrogen-containing heterocyclic ring, and the nitrogen-containing heterocyclic ring may be condensed with an aromatic ring. The fused ring may have a substituent; V ¹ represents a monovalent substituent; n is 1, 2, 3, or 4; and m is an integer from 0 to 4.

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

[0018]

According to the present invention, when a specific compound is used as a dye for a photothermographic material, an excellent image having little residual color can be formed. In addition, a thermal decolorable recording material can be prepared using a specific compound. Furthermore, in the method for decoloring a dye of the present invention, a relatively stable dye can be rapidly and substantially decolored by an intramolecular ring closing mechanism.

[0019]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, a dye represented by the following formula (1) is used.

[0020]

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In the formula (1), 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 , and particularly preferably —NR ²¹ R ²⁶ . R ²¹ is preferably an aliphatic group or an aromatic group, more preferably an alkyl group, a substituted alkyl group, an aralkyl group, 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. The nitrogen-containing heterocyclic ring formed by combining R ²¹ 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). -N
In R ²¹ R ²⁶ , R ²⁶ is preferably a hydrogen atom, and R ²¹ is preferably an alkyl group, a substituted alkyl group, an aryl group or a substituted aryl group. In —OR ²¹ , R ²¹ is preferably an alkyl group.

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, sulfo,
An acyl group, an alkoxy group, an alkoxycarbonyl group, an alkylthio group, an alkylthiocarbonyl group, an aryloxy group, an aryloxycarbonyl group and a carbamoyl group are included. 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" refers to an aryl group or a substituted aryl group. The aryl group preferably has 6 to 30 carbon atoms,
It is more preferably from 20 to 20, more preferably from 6 to 15, and most preferably from 6 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, nitro, carboxyl, sulfo,
It includes an alkyl group, an acyl group, an alkoxy group, an alkoxycarbonyl group, an alkylthio group, an alkylthiocarbonyl group, an aryloxy group, an aryloxycarbonyl group and a carbamoyl 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 (1), 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 (1), 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 cyclopentene ring or a cyclohexene ring. It is particularly preferred that methine is unsubstituted or forms a cyclopentene ring or a cyclohexene ring. In the formula (1), n is 1, 2, 3, 4
Which is preferably 1, 2, or 3, and more preferably 1, 2. When n is 2 or more, the methine group is repeated but need not be the same. In equation (1),
Z ¹ is an atomic group forming a 5- or 6-membered nitrogen-containing heterocyclic ring. Examples of the nitrogen-containing heterocycle include an oxazole ring, a thiazole ring, a selenazole ring, a pyrrole ring, a pyrroline ring, an imidazole ring and a pyridine ring. Five-membered rings are preferred over six-membered rings. An aromatic ring (benzene ring, naphthalene ring) may be condensed with the nitrogen-containing heterocycle, and examples thereof include an indolenine ring, a benzoxazole ring, a naphthoxazole ring, a benzothiazole ring, a benzimidazole ring, and a quinoline ring. Can be The nitrogen-containing heterocycle and its condensed ring may have a substituent. Examples of the substituent preferably include a halogen atom (a fluorine atom, a chlorine atom, and a bromine atom), a hydroxyl, a nitro, a carboxyl, a sulfo, an aryl group, 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).

The dye represented by the formula (1) preferably forms a salt with an anion. When the dye represented by the formula (1) has an anionic group such as carboxyl or sulfo as a substituent, the dye can form an inner salt. Otherwise, the dye preferably forms a salt with an extramolecular anion. The anion is preferably monovalent or divalent, and more preferably monovalent. Examples of anions include halogen ions (Cl,
Br, I), p-toluenesulfonic acid ion, ethyl sulfate ion, 1,5-disulfonaphthalenedianion, P
F ₆ , BF ₄ and ClO ₄ are included. The aromatic hetero ring represented by A is preferably a 5- or 6-membered aromatic hetero ring, and examples thereof include pyrrole, indole, indazole, furan, thiophene, imidazole, pyrazole,
Indolizine, quinoline, thiazole, isothiazole, pyridine, pyrazine, pyrimidine, pyridazine, thiadiazine, oxadiazol, thiadiazole, pyrrolothiazole, pyrrolopyridazine, oxazole, isoxazole, and isoxazole include benzene ring or naphthalene ring. The rings may be fused. Among them, preferred are pyrrole, indole, furan, thiophene, pyridine, quinoline, and oxazole, and particularly preferred are pyrrole, indole, furan and thiophene. Each of these aromatic heterocycles may have a substituent. Examples of the substituent include an amino group (eg, unsubstituted amino, dimethylamino, anilino, bis (2-cyanoethyl) amino), a lower alkyl group (eg, methyl, ethyl), an alkoxy group (eg, methoxy, ethoxy) Phenoxy group (eg, unsubstituted phenoxy, p-chlorophenoxy), halogen atom (C
l, Br, F), an alkoxycarbonyl group (for example, ethoxycarbonyl), a cyano group, a nitro group and the like. Particularly, an amino group, a lower alkyl group and an alkoxy group can be mentioned as preferred substituents. V ¹ may be any monovalent substituent, and examples include the substituents represented by R ¹ described above. It is preferably a substituted or unsubstituted alkyl group or a substituted or unsubstituted alkoxy group, and more preferably an unsubstituted alkyl group. In the formula (2), m is 0, 1, 2, 3
Or represents 4, preferably 0 and 1, more preferably 0. In the formula (2), R ³ represents an aliphatic group, an aromatic group, or a heterocyclic group. The definitions of aliphatic and aromatic are as described above. R ³ is preferably an aliphatic group, an aromatic group, or a heterocyclic group. More preferably, an unsubstituted aliphatic group (eg, methyl, ethyl, butyl), a substituted aliphatic group (eg, 2-sulfoethyl, 3-
Sulfopropyl, 4-sulfobutyl, carboxymethyl, 2-carboxyethyl), unsubstituted aromatic group (eg, phenyl, naphthyl), unsubstituted heterocyclic group (eg,
2-pyridyl, 2-thiazolyl), and particularly preferably a substituted or unsubstituted aliphatic group. Most preferably, it is an unsubstituted aliphatic group. Hereinafter, specific examples of the dye represented by the formula (1) will be shown.

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Synthesis Example 1 Synthesis of Dye (1) To 50 ml of ethanol, 4.0 g of compound A and 1.5 g of compound B were added, and the mixture was heated under reflux for 1 hour. The obtained crystals were separated by suction filtration, washed with ethanol, and dried to obtain 2.9 g of (1). (55% yield),
λmax = 436.3nm) (ε = 2.8 × 10 4) ( in methanol).

[0053]

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Other dyes can be synthesized in the same manner as in Synthesis Example 1 described above.

The dye of the present invention or a salt thereof can be decolorized by the action of a base under heating conditions. According to the study of the present inventors, the dye of the present invention deprotonates the active methylene group in the dye by the action of a base,
It has been found that the resulting nucleophile attacks the methylene chain in the molecule by nucleophilic attack and forms an intramolecular closed form, thereby discoloring. 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 dye. Therefore, the decoloring method of the present invention does not have a problem that the decolored substance is recolored. The decolorization reaction proceeds in a solvent system or a non-solvent system.
When performing a decolorization reaction in a solvent system, it is preferable to heat a solution of the dye and a base (or a base precursor).
As a solvent, a dye and a base (or a base precursor)
Is a substance that is liquid at the heating temperature (described below) (eg, dimethylsulfoxide, dimethylacetamide)
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 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 dye, the decoloring reaction slightly proceeds even at room temperature. Therefore, it is preferable that the base is physically or chemically isolated from the dye, and the base and the dye are contacted (reacted) during heating (when the color is to be erased). Means for physically isolating the base include means such as use of microcapsules, addition of a heat-fusible substance into fine particles, or addition to a layer different from the layer containing a dye in a recording material or a photosensitive material. There is. 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 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. Regarding thermoresponsive microcapsules, see Hiroyuki Moriga, Introduction to Specialty Paper Chemistry (1975), and
It is described in -150575. A base or a dye (preferably a base) may be added to the fine particles of a heat-fusible substance such as a 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 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.

The chemical isolation means is easier to implement than the physical isolation means and is preferred. 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-168441 describes the base precursor of propiolate and JP-A-59-180537 describes each of them. 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 used amount (mol) of the base precursor is preferably 1 to 100 times, more preferably 3 to 30 times the used amount (mol) of the dye. Dyes can be used for various applications by utilizing the above-described decolorization reaction. For example, a solution of a dye and a base precursor can be used as the thermal decolorizable ink. Further, a solution obtained by applying a solution of a dye and a base precursor to a transparent support can be used as a heat-decolorable sheet (filter). Further, a dye and a base precursor can be applied to a heat-decolorable recording material. The heat-decolorable recording material has a recording layer on a support (preferably a transparent support). The dye is dispersed in the recording layer in the form of molecules or solid fine particles. When molecularly dispersed, a dye solution is added to the coating solution for the recording layer. In the case of dispersing in the form of solid fine particles, a dispersion of solid fine particles of a 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 a binder,
A hydrophilic polymer (eg, polyvinyl alcohol, gelatin) is preferably used. By performing imagewise heating, the heat-erasable recording material can form an image by erasing the heated portion. Imagewise heating can be easily performed using a thermal head used in a facsimile or thermal printer.

A particularly advantageous use of the present invention is a photothermographic material. A photothermographic material generally has a non-photosensitive layer in addition to a photosensitive layer. The dye according to the present invention is added to at least one of the photosensitive layer and the non-photosensitive layer of the photothermographic material, and the dye and the base precursor are added to at least one of the non-photosensitive layers, Preferably, the non-photosensitive layer functions as a filter layer or an antihalation 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 (1) or (2)
Is provided on the photosensitive material. The antihalation layer is provided on the photosensitive material as the layer (3) or (4). It is preferable that the dye and the base precursor are 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. As used herein, "the layer contains a dye and a base precursor"
The case where there are a plurality of “layers”, that is, the case where a plurality of layers separately contain a dye and a base precursor is also included.

As a method of adding the 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. Latex used in polymer impregnation is disclosed in US Pat.
No. 363, West German Patent Publication Nos. 25141274 and 254
No. 1230, European Patent Publication No. 029104 and Japanese Patent Publication No. 53-41091. Further, the emulsification method of adding a dye to a solution in which a polymer is dissolved is described in International Publication No. 88/00723. The amount of the dye to be added is determined depending on the use 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 0.00
It is about 1 to 1 g / m ² . When the dye is decolored according to the present invention, the optical density can be reduced to 0.1 or less. Two or more dyes may be used in combination in a heat-decolorable 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 the 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 aminohydroxycycloalkenone compounds (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 sulfonamide phenols, α-cyanophenylacetic acid derivatives, bis-β- Naphtho Of 1,3-dihydroxybenzene derivatives, 5-pyrazolones, sulfonamidophenols, 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) functioning 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, polyvinylpyrrolidone, 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 mass of the binder. The dye is preferably 0.2 to 30% by mass of the binder,
Most preferably, it is 0.5 to 10% by mass. 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 light-sensitive layer or the non-light-sensitive 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 coating solution for the photosensitive layer. 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.
No. 558983). The photosensitive layer or the non-photosensitive layer preferably further contains a color tone adjuster. The color tone adjuster 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 furalazine 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. 3,874).
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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[Example 1] (Decoloring reaction of dye) 1 g of the dye (1) was dissolved in 10 ml of dimethyl sulfoxide, 1 ml of triethylamine was added, and the mixture was heated at 120 ° C for 1 minute. Immediately after the start of heating, the yellow color of the solution disappeared, and the solution became a colorless 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, and has a mass spectrum and 1
The H-NMR spectrum showed that the compound was ring-closed and decolored 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, a solution was prepared by dissolving the dye (1) in deuterated dimethylsulfoxide-d6 without adding a base. This solution was heated at 160 ° C. for 2 hours, and the presence or absence of a reaction was observed by 1 H-NMR measurement. However, no reaction was confirmed, and it was found to be extremely stable when no base was present.

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 ^-4 mol / dm
^{3 was} added 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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[Of 75]

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Example 3 (Preparation of solid dispersion of base precursor) 3% by mass of polyvinyl alcohol was placed in a 300 ml dispersion container.
52.5 g of an aqueous solution, 52.5 g of a 3% by mass aqueous solution of carboxymethyl cellulose, and a base precursor (BP-4
1) 40 g and 150 ml of glass beads having a diameter of 0.5 to 0.75 mm were put therein. 3000 using Dynomill
The mixture was dispersed at 30 rpm for 30 minutes, the pH was adjusted to 6.5 with 2N sulfuric acid, and a solid dispersion of a base precursor having a particle size of about 1 μm was obtained.

(Preparation of fine particle dispersion of dye) Dye (6)
1.6 g was dissolved in 30 g of ethyl acetate. Separately, 31 g of a 20% by mass aqueous solution of polyvinyl alcohol, 21 g of water and 5% by mass of sodium dodecylbenzenesulfonate
10 g of the aqueous solution was mixed and placed in a 200 ml homogenizer cup. A solution of the dye was added thereto, and 1000
The mixture was stirred at 0 rpm for 5 minutes to obtain a dye emulsion. After stirring the emulsion at 50 ° C. for 2 hours to remove ethyl acetate,
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) To 5.1 g of a fine particle dispersion of a dye, 0.5 g of water and a 20% by mass aqueous solution of polyvinyl alcohol were added 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. On a polyethylene terephthalate film (support) provided with a gelatin subbing layer having a thickness of 100 μm, a coating amount of 10.5 g /
m ² and dried. 4 g of a 10% by weight aqueous solution of polyvinyl alcohol, 2% by weight aqueous solution of poly (n = 10) ethylene glycol dodecyl ether (surfactant) 1
g, 0.5 g of a 20% by mass 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 a protective layer. This coating solution is applied on the thermal decoloring recording layer,
It was applied at a coating amount of 17.5 g / m ² and dried to prepare a heat-decolorable recording material.

(Formation of Thermal Decoloring Image) The thermal decoloring type recording material was subjected to eight gradation steps using a thermal imager (FTI210, manufactured by Fuji Photo Film Co., Ltd.).
Upon imagewise heating, a negative was obtained in which the high energy portions were 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 the 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 Dye Emulsion) Dye (12)
8 g 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 mass aqueous solution of polyvinyl alcohol and emulsified at room temperature to obtain an emulsion of a dye having an average particle diameter of 1.2 μm.

(Preparation of Coating Solution for Antihalation Layer) 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 of polyvinyl alcohol 28.
In addition, the mixture was stirred to prepare an antihalation layer coating solution.

(Formation of Antihalation Layer) Thickness is 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 part 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
And 270 μmol of thiocyanic acid are added,
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 m of 1 (mol / L) aqueous sodium hydroxide solution
1 was added and reacted for 60 minutes. After adding 65 ml of 1 (mol / L) nitric acid, the temperature was lowered to 50 ° C. Then
While stirring more vigorously, 0.62 g of N-bromosuccinimide was added, and 10 minutes later, the above-mentioned silver halide emulsion was added such that the amount of silver halide became 6.2 mmol. Further, 125 ml of an aqueous solution of 21 g of silver nitrate was added to 1
The mixture was added over 00 seconds, and was continuously stirred for 10 minutes.
-0.62 g of bromosuccinimide were added and an additional 1
Left for 0 minutes. Then, the solid content was filtered off by suction filtration,
The solid was washed with water until the conductivity of the filtrate reached 30 μS / cm. 150 g of a 0.6% by mass butyl acetate solution of polyvinyl acetate was added to the solid content thus obtained, followed by stirring. After stirring, leave to separate oil phase and aqueous phase,
The aqueous phase containing the salt was removed to obtain an oily phase. Next, polyvinyl butyral (denka butyral # 3000-K,
80 g of a 2.5 mass% 2-butanone solution (produced by Denki Kagaku Kogyo KK) was added and stirred. Pyridinium perbromide
1 mmol and 0.15 mol of calcium bromide dihydrate were added together with 0.7 g of methanol. Further, 200 g of 2-butanone and polyvinyl butyral (BUTVAR-7
6, manufactured by Mondant Co.) and dispersed with a homogenizer to form an organic silver salt emulsion (average minor axis of needle-like particles: 0.0
4 μm, average major axis: 1 μm, variation coefficient 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.

成分 Photosensitive layer coating solution components (primary addition) ─ナ ト リ ウ ム Sodium phenylthiosulfonate 10mg The following pigment 80mg 2-mercapto-5 -Methylbenzimidazole 2 g 4-chlorobenzophenone-2-carboxylic acid 21.5 g 2-butanone 580 g dimethylformamide 220 g ──────────

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成分 Photosensitive layer coating solution components (secondary addition) ５− 5-tribromomethylsulfonyl-2-methylthiadiazole 8 g 2- Tribromomethylsulfonylbenzothiazole 6g 4,6-Ditrichloromethyl-2-phenyltriazine 5g The following disulfide compound 2g 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethyl Hexane 155 g Fluorosurfactant (Megafax F-176P, manufactured by 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 106)
In the preparation of the photothermographic material 101, the dye (5), the dye (6), the dye (26) and the comparative dye 1 were used in place of the dye (12), except that each was used. 102 to 105 were created. The dye (1
A photothermographic material 106 was prepared in the same manner as the photothermographic material 101 except that 2) was not added.
The dyes (5) and (26) were used by preparing solid fine particle dispersions by the following method. The amounts used were (6) and Comparative Dye (1) in the same amount, and (5) and (26) were used in three times the amount. (Preparation of solid dispersion of dye) 3% by weight aqueous solution of polyvinyl alcohol in a 300 ml dispersion container
5 g, 3% by mass aqueous solution of carboxymethyl cellulose 5
2.5 g, 40 g of dye (5) or (26) and 150 ml of zirconia silicate beads having a diameter of 0.5 mm were charged. The mixture was dispersed at 3000 rpm for 30 minutes using a Dynomill to obtain a solid dispersion of a dye having a particle size of about 0.5 μm.

(Evaluation of Photographic Performance) After exposing the photothermographic material with a 635 nm semiconductor laser photometer, the photothermographic material was processed at 120 ° C. for 15 seconds (heat development), 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). The results are shown in Table 2. 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. The results are shown in Table 2.

(Evaluation of Storage Stability) Photothermographic Material 101
To 106 at high temperature (50 ° C.) and high humidity (80% relative humidity).
%) For 3 days, and the absorbance at 600 nm was measured before and after storage. The absorbance (Db) of the photosensitive materials 101 to 105 before storage, the absorbance after storage (Da), and the absorbance of the photosensitive material 106 without dye after storage (D
From the measurement result of 0), the photosensitive materials 101 to 1 were obtained by the following formulas.
The residual ratio of the dye in Sample No. 05 was determined and used as an index of storage stability. The photosensitive material 106 has a thickness of 600 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. The results are shown in Table 2.

[0147]

[Table 2]

[0148]

According to the present invention, a photothermographic material having excellent decolorability and storage stability can be provided. In addition, it is possible to provide a thermal decoloring type recording material having excellent storage stability. Further, it is possible to provide a method of decoloring a dye which is stable at room temperature and rapidly decolors by heating.

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 of the photosensitive layer and the non-photosensitive layer has the following formula: A photothermographic material comprising the dye represented by (1) 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 a substituted or unsubstituted methine, and the substituents of methine are bonded to each other to form an unsaturated aliphatic ring or an unsaturated heterocyclic ring; A represents an aromatic heterocyclic ring or a general formula (2);
R ³ represents an aliphatic group, an aromatic group, or a heterocyclic group. Z ¹
Is an atomic group necessary for completing a 5- or 6-membered nitrogen-containing heterocyclic ring, and the nitrogen-containing heterocyclic ring may be condensed with an aromatic ring. May have a substituent; V ¹ represents a monovalent substituent; n
Is 1, 2, 3 or 4; and m is 0 to 4
Is an integer. 2. A recording material having a recording layer on a support, wherein at least one recording layer contains a dye represented by the following formula (1) and a base precursor, and the dye is in the form of molecules or solid fine particles. A recording material characterized by being dispersed in a recording layer. 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 a substituted or unsubstituted methine, and the substituents of methine are bonded to each other to form an unsaturated aliphatic ring or an unsaturated heterocyclic ring; A represents an aromatic heterocyclic ring or a general formula (2);
R ³ represents an aliphatic group, an aromatic group, or a heterocyclic group. Z ¹
Is an atomic group necessary for completing a 5- or 6-membered nitrogen-containing heterocyclic ring, and the nitrogen-containing heterocyclic ring may be condensed with an aromatic ring. May have a substituent; V ¹ represents a monovalent substituent; n
Is 1, 2, 3 or 4; and m is 0 to 4
Is an integer. 3. A method for decoloring a dye represented by the following formula (1) by causing a base to act on the dye 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 a substituted or unsubstituted methine, and the substituents of methine are bonded to each other to form an unsaturated aliphatic ring or an unsaturated heterocyclic ring; A represents an aromatic heterocyclic ring or a general formula (2);
R ³ represents an aliphatic group, an aromatic group, or a heterocyclic group. Z ¹
Is an atomic group necessary for completing a 5- or 6-membered nitrogen-containing heterocyclic ring, and the nitrogen-containing heterocyclic ring may be condensed with an aromatic ring. May have a substituent; V ¹ represents a monovalent substituent; n
Is 1, 2, 3 or 4; and m is 0 to 4
Is an integer. 4. The method for erasing a dye according to claim 3, wherein the heating causes the dye to be decolorized by an intramolecular ring closure reaction.