JP2007206673A - Heat developable photosensitive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the decolorability of a dye and the water resistance of a processed image. <P>SOLUTION: A heat developable photosensitive material having at least one photosensitive layer on a support is provided, wherein the heat developable photosensitive material has a non-photosensitive layer containing a compound represented by formula (I), wherein R<SP>01</SP>and R<SP>02</SP>each independently represent an aliphatic group, an aromatic group or a heterocyclic group. The compound represented by the formula (I) does not have a carboxyl group or a salt of a carboxyl group as a substituent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a photothermographic material, and more particularly to a photothermographic material excellent in dye decolorization and water resistance of processed images.

  Photothermographic materials have already been proposed for a long time (see, for example, Patent Documents 1 and 2 and Non-Patent Document 1 below). Photothermographic materials generally contain a catalytically active amount of a photocatalyst (eg, silver halide), a reducing agent, a reducible silver salt (eg, an organic silver salt), and, if necessary, a toning agent that controls the color tone of silver. A photosensitive layer dispersed in the matrix. The photothermographic material is heated to a high temperature (for example, 80 ° C. or higher) after image exposure, and is blackened by an oxidation-reduction reaction between silver halide or a reducible silver salt (functioning as an oxidizing agent) and a reducing agent. Form a silver image. The oxidation-reduction reaction is promoted by the catalytic action of the latent image of silver halide generated by exposure. Therefore, a black silver image is formed in the exposure area.

  The thermal development process does not require a processing solution in the wet development process, and has an advantage that it can be processed easily and quickly. However, in the field of photographic technology, image forming methods by wet development are still mainstream. This is because the thermal development process still has unsolved problems that are not present in the wet development process.

  It is usual to add a dye to a photographic light-sensitive material for the purpose of preventing a filter, halation and irradiation. The dye is added to the non-photosensitive layer and functions in image exposure. When the dye whose function has been completed remains in the photographic light-sensitive material, the formed image is colored with the dye. Therefore, it is necessary to remove the dye from the photographic light-sensitive material in the development process. In the wet development processing, the dye can be easily removed from the photographic light-sensitive material with a processing solution. On the other hand, in the heat development process, it is very difficult (substantially impossible) to remove the dye.

  In recent photographic technology, particularly in the technical field 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 photographs and printing photographs, an image forming method based on heat development processing has attracted attention again.

  In order to solve the problem that it is very difficult to remove the dye in the heat development process, a method of erasing the dye by heating in the heat development process has been proposed. For example, Patent Document 3 below discloses a method of decolorizing a polymethine dye having a specific structure by heating. Patent Documents 4 to 6 below disclose methods for decoloring by heating a polymethine dye using a carbanion generator.

However, in the conventional method, the color erasure is insufficient and the film is not sufficiently transparent within a desired time, or if the color erasure is fast, the water resistance after the treatment is difficult. That is, when water droplets are accidentally dropped or stored under conditions of high humidity, there is a problem that transparency is lost and unevenness occurs.
US Pat. No. 3,152,904 US Pat. No. 3,457,075 US Pat. No. 5,135,842 US Pat. No. 5,314,795 US Pat. No. 5,324,627 US Pat. No. 5,384,237 "Imaging Processes and Materials" Neblette 8th edition, edited by Sturge, V. Walworth, A. Shepp, page 2, 1996) (Shely's "Thermally Processed Silver Systems" item)

  Accordingly, an object of the present invention is to provide a photothermographic material having an increased decoloring speed and improved water resistance of a coating film when the dye is decolored by heating in heat development processing.

The object of the present invention has been achieved by the following (1) to (7).
(1) A photothermographic material having a non-photosensitive layer containing a compound represented by the following formula (I) in a photothermographic material having at least one photosensitive layer on a support.

[In Formula (I), R ⁰¹ and R ⁰² each independently represents an aliphatic group, an aromatic group or a heterocyclic group. However, the compound represented by the formula (I) does not have a carboxyl group or a carboxyl group salt as a substituent. ]
(2) The photothermographic material according to (1) above, comprising silver halide, organic silver salt, reducing agent and binder.
(3) having at least one non-photosensitive layer containing a base-bleachable dye or a salt thereof, wherein at least one of the non-photosensitive layer and its adjacent non-photosensitive layer has a base precursor and formula (I) The photothermographic material according to the above (1) or (2), which contains a compound represented by the formula:
(4) The photothermographic material according to (3), wherein a base precursor and a compound represented by formula (I) are co-dispersed and contained.
(5) The photothermographic material according to any one of (1) to (4), wherein the non-photosensitive layer and its adjacent non-photosensitive layer are on the opposite side of the photosensitive layer from the support.
(6) The photothermographic material according to any one of (1) to (5) above, wherein the dye capable of being bleached by the base or a salt thereof is a cyanine dye represented by the following formula (II).

[In the formula (II), R ¹ represents an electron-withdrawing group, R ² represents a hydrogen atom, an aliphatic group or an aromatic group, and R ³ and R ⁴ each independently represents a hydrogen atom, a halogen atom or an aliphatic group. Group, aromatic group, —NR ⁶ R ⁷ , —OR ⁶ or —SR ⁷ , R ⁶ and R ⁷ each independently represent a hydrogen atom, an aliphatic group or an aromatic group, and R ⁵ represents an aliphatic group L ¹ , L ² and L ³ are each independently an optionally substituted methine, and the methine substituent is bonded to form an unsaturated aliphatic ring or an unsaturated heterocyclic ring. May be. Z ¹ and Z ² are each independently an atomic group forming a 5- or 6-membered nitrogen-containing heterocycle, and the nitrogen-containing heterocycle may be condensed with an aromatic ring, and the nitrogen-containing heterocycle And the condensed ring thereof may have a substituent. m represents 0, 1, 2, or 3. ]
(7) The photothermographic material according to any one of (1) to (6), wherein the base precursor is a diacid base precursor.

  According to the present invention, an image with little residual color and excellent water resistance can be formed.

Hereinafter, the present invention will be described in detail.
A substance that lowers the melting point by 3 ° C. (deg) or more when mixed with the base precursor in the present invention (hereinafter referred to as a melting point depressant) has a melting point of 3 ° C. lower than the melting point of the base precursor alone. What is 3-20 degreeC low is more preferable, and what becomes 5-15 degreeC lower is still more preferable. If two types of powders, a base precursor and a melting point depressant, are mixed in a mortar and differential scanning calorimetry (DSC) is performed on the sample, a change in melting point can be observed. Two or more melting point depressants may be used in combination.

  In addition, the melting point depressant may be a substance that lowers the melting point by 3 ° C. (deg) or more with one kind of compound, or the melting point may be lowered by 3 ° C. or more only when two or more kinds of compounds are used.

  The addition method is preferably added as a co-dispersion of a mixture with a base precursor, and particularly preferably as a solid fine particle dispersion. In this case, the average particle diameter of the fine particles is preferably 0.03 to 0.3 μm.

  The melting point depressant used for such a purpose is not particularly limited as long as it satisfies the conditions described above. Among them, those having a melting point equal to or higher than that of the base precursor are preferred, those having a melting point of 50 ° C. to 200 ° C. are more preferred, and those having a melting point of 70 ° C. to 150 ° C. are more preferred. In the present invention, the base precursor and the melting point depressant can be used in any ratio, and such a melting point depressant is more preferably stable to the base.

  As a compound satisfying this condition, for example, a compound generally used as a thermal solvent can be used. Specifically, waxes (for example, paraffin wax, microcrystalline wax, fatty acid amide wax, stearic acid amide, ethylene bisstearamide), amides (for example, benzamide, N-methylbenzamide, fatty acid amide, acetoacetanilide, etc.) , Sulfonamides (eg p-toluenesulfonamide, N-methylbenzenesulfonamide, etc.), carboxylic acid esters (eg phenyl benzoate, dimethyl terephthalate, diphenyl phthalate etc.), aryl nitriles, phenol derivatives (eg 2,6 -Di-tert-butyl-4-methylphenol, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone), naphthol derivatives (eg benzyl-1-naphthyl ether, phenoxyacetic acid-2-naphthyl ester, etc.), Alcohol For example, sorbitol, etc.), urea derivatives (for example, N-methylurea, N-phenylurea, N, N-dimethyl-N′-phenylurea, etc.), urethanes (phenylcarbamoyloxydecane, p-tolylcarbamoyloxybenzene, etc.) ), Substituted biphenyls (eg 4- (2-phenylethoxy) biphenyl, biphenylphenylmethane, 4-acetyloxybiphenyl), ethers (eg 1,2-diphenoxyethane, 1,4-bis (p-tolyloxy) ) Butane), thioethers (eg 1,2-bis (p-methoxyphenylthio) ethane), aromatic hydrocarbons (eg bibenzyl, biphenyl, triphenylmethane), benzotriazole derivatives (2- (2 '-Hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-4', 6'-di-tert-pentylphenyl) benzotriazol Etc.), sulfones (such as diphenyl sulfone, bis (4-chlorophenyl) sulfone, 4-chlorophenyl (phenyl) sulfone, 4- (phenylsulfonyl) phenylsulfonyl methane, methane sulfonyl benzene), and the like.

  Of these, amides, phenol derivatives, naphthol derivatives, benzotriazole derivatives and sulfones are more preferred.

  Formula (I) will be described in detail. The “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. The chain aliphatic group may have a branch.

  The alkyl group preferably has 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and still more preferably 1 to 15 carbon atoms. The alkyl part of the substituted alkyl group is the same as the alkyl group.

  The number of carbon atoms in the alkenyl group and alkynyl group is preferably 2 to 30, more preferably 2 to 20, and still more preferably 2 to 15. 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 alkynyl group, respectively.

  “Aromatic group” means an aryl group or a substituted aryl group. The number of carbon atoms of the aryl group is preferably 6 to 30, more preferably 6 to 20, and still more preferably 6 to 15. The aryl part of the substituted aryl group is the same as the aryl group.

  “Heterocyclic group” means a 5- or 6-membered heterocyclic or substituted heterocyclic group. The heterocyclic portion of the substituted heterocyclic group is the same as the heterocyclic group.

  Examples of heterocyclic groups include pyrrole, indole, furan, thiophene, imidazole, pyrazole, indolizine, quinoline, carbazole, phenothiazine, indoline, thiazole, pyridine, pyridazine, thiadiazine, pyran, thiopyran, oxadiazole, Examples include benzoquinoline, thiadiazole, pyrrolothiazole, pyrrolopyridazine, tetrazole, oxazole, coumarin, and chroman. Each of these may have a substituent.

  The substituent that each group described above may have is not particularly limited as long as it is other than a carboxyl group and a salt of the carboxyl group. Examples of the substituent include a sulfonamide group having 1 to 20 carbon atoms (for example, methanesulfonamide, benzenesulfonamide, butanesulfonamide, n-octanesulfonamide), and a sulfamoyl group having 0 to 20 carbon atoms (for example, unsubstituted sulfamoyl group). Methylsulfamoyl, phenylsulfamoyl, butylsulfamoyl), a sulfonylcarbamoyl group having 2 to 20 carbon atoms (for example, methanesulfonylcarbamoyl, propanesulfonylcarbamoyl, benzenesulfonylcarbamoyl), an acylsulfur having 1 to 20 carbon atoms. Moyl group (for example, acetylsulfamoyl, propionylsulfamoyl, benzoylsulfamoyl), linear or cyclic alkyl group having 1 to 20 carbon atoms (for example, methyl, ethyl, cyclohexyl, 2-hydroxyethyl, -Carboxybutyl, 2-methoxyethyl, benzyl, 4-carboxybenzyl, 2-diethylaminoethyl), an alkenyl group having 2 to 20 carbon atoms (for example, vinyl, allyl), an alkoxy group having 1 to 20 carbon atoms (for example, methoxy, ethoxy) , Butoxy), halogen atoms (for example, F 2, Cl, Br), amino groups having 0 to 20 carbon atoms (for example, unsubstituted amino group, dimethylamino, diethylamino, carboxyethylamino), alkoxycarbonyl groups having 2 to 20 carbon atoms (For example, methoxycarbonyl), amide group having 1 to 20 carbon atoms (for example, acetamido, benzamide), carbamoyl group having 1 to 20 carbon atoms (for example, unsubstituted carbamoyl, methylcarbamoyl, phenylcarbamoyl), aryl having 6 to 20 carbon atoms Groups such as phenyl, naphthyl, 4-carboxypheny , 4-methanesulfonamidophenyl, 3-benzoylaminophenyl), aryloxy groups having 6 to 20 carbon atoms (for example, phenoxy, 3-methylphenoxy, naphthoxy), alkylthio groups having 1 to 20 carbon atoms (for example, methylthio, octylthio) ), An arylthio group having 6 to 20 carbon atoms (for example, phenylthio, naphthylthio), an acyl group having 1 to 20 carbon atoms (for example, acetyl, benzoyl, 4-chlorobenzoyl), a sulfonyl group having 1 to 20 carbon atoms (for example, methanesulfonyl, Benzenesulfonyl), ureido group having 1 to 20 carbon atoms (for example, methylureido, phenylureido), alkoxycarbonylamino group having 2 to 20 carbon atoms (for example, methoxycarbonylamino, hexyloxycarbonylamino), cyano group, hydroxyl group, nitro group , Heterocyclic groups (e.g. 5-ethoxycarbonylbenzoxazole ring, pyridine ring, sulfolane ring, furan ring, pyrrole ring, pyrrolidine ring, morpholine ring, piperazine ring, pyrimidine ring) and the like.

R ⁰¹ is preferably an aromatic group, and more preferably as a substituent of the substituted aryl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, an acyl group, Examples include a sulfonyl group, an alkoxycarbonyl group, an alkoxy group, a substituted or unsubstituted carbamoyl group, and a halogen atom. A substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a sulfonyl group, an alkoxy group and a halogen atom are more preferred, and a substituted or unsubstituted alkyl group, a sulfonyl group and a halogen atom are most preferred.

R ⁰² is preferably an aliphatic group or an aromatic group. When R ⁰² is aliphatic, it is preferably an alkyl group, a substituted alkyl group, an aralkyl group or a substituted aralkyl group, more preferably an alkyl group or an aralkyl group.

When R ⁰² is an aromatic group, more preferable examples of the substituent for the substituted aryl group include a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, Examples include an acyl group, a sulfonyl group, an alkoxycarbonyl group, an alkoxy group, a substituted or unsubstituted carbamoyl group, and a halogen atom. A substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a sulfonyl group, an alkoxy group and a halogen atom are more preferred, and a substituted or unsubstituted alkyl group, a sulfonyl group and a halogen atom are most preferred.

  The melting point depressant is preferably used in an amount of 1% by weight to 500% by weight, more preferably 5% by weight to 200% by weight of the base precursor.

  Specific examples of the compound represented by formula (I) are shown below, but are not limited thereto.

  The dye that can be bleached with a base or a salt thereof (hereinafter sometimes referred to as a decoloring dye) used in the present invention is preferably a cyanine dye represented by the formula (II) or a salt thereof.

In the formula (II), R ¹ represents an electron-withdrawing group, R ² represents a hydrogen atom, an aliphatic group or an aromatic group, and R ³ and R ⁴ each independently represent a hydrogen atom, a halogen atom or an aliphatic group. Group, aromatic group, —NR ⁶ R ⁷ , —OR ⁶ or —SR ⁷ , R ⁶ and R ⁷ each independently represent a hydrogen atom, an aliphatic group or an aromatic group, and R ⁵ represents an aliphatic group L ¹ , L ² and L ³ are each independently an optionally substituted methine, and the methine substituent is bonded to form an unsaturated aliphatic ring or an unsaturated heterocyclic ring. May be. Z ¹ and Z ² are each independently an atomic group forming a 5- or 6-membered nitrogen-containing heterocycle, and the nitrogen-containing heterocycle may be condensed with an aromatic ring, and the nitrogen-containing heterocycle And the condensed ring thereof may have a substituent. m represents 0, 1, 2, or 3.

Formula (II) will be described in detail. In the formula (II), R ¹ represents an electron-withdrawing group, and the degree thereof is Hammett's substituent constant σ _m (described in Chem. Rev., 91, 165 (1991).) Of 0.3 or more. Those of 1.5 or less are preferred, and examples thereof include a substituent represented by —C (═O) R ¹¹ , —SO _p R ¹² , and a cyano group, and —C (═O) R ¹¹ is preferred. R ¹¹ represents a hydrogen atom, an aliphatic group, an aromatic group, —OR ¹³ , —SR ¹³ or —NR ¹³ R ¹⁴ , and R ¹² represents an aliphatic group, an aromatic group, —OR ¹³ or —NR ¹³ R ¹⁴ represents p, and 1 represents 1 or 2. Here, R ¹³ and R ¹⁴ are each independently a hydrogen atom, an aliphatic group, or an aromatic group, or R ¹³ and R ¹⁴ are combined to form a nitrogen-containing heterocycle. More preferably the R ¹ is -C (= O) R ^11, of which R ¹¹ is more preferably a -OR ¹³ or -NR ¹³ R ^14, is -NR ¹³ R ¹⁴ in terms of storability of the light-sensitive material Most preferred.

  The “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 to a cyclic aliphatic group. The chain aliphatic group may have a branch. The alkyl group preferably has 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and still more preferably 1 to 15 carbon atoms. The alkyl part of the substituted alkyl group is the same as the alkyl group.

  The number of carbon atoms in the alkenyl group and alkynyl group is preferably 2 to 30, more preferably 2 to 20, and still more preferably 2 to 15. 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 alkynyl group, respectively.

  “Aromatic group” means an aryl group or a substituted aryl group. The number of carbon atoms of the aryl group is preferably 6 to 30, more preferably 6 to 20, and still more preferably 6 to 15. The aryl part of the substituted aryl group is the same as the aryl group.

  There is no restriction | limiting in particular in the substituent which each group mentioned above may have. For example, a carboxyl group (which may be a salt), a sulfo group (which may be a salt), a sulfonamide group having 1 to 20 carbon atoms (for example, methanesulfonamide, benzenesulfonamide, butanesulfonamide, n- Octanesulfonamide), sulfamoyl group having 0 to 20 carbon atoms (for example, unsubstituted sulfamoyl, methylsulfamoyl, phenylsulfamoyl, butylsulfamoyl), sulfonylcarbamoyl group having 2 to 20 carbon atoms (for example, methanesulfonylcarbamoyl) , Propanesulfonylcarbamoyl, benzenesulfonylcarbamoyl), acylsulfamoyl group having 1 to 20 carbon atoms (for example, acetylsulfamoyl, propionylsulfamoyl, benzoylsulfamoyl), linear or cyclic having 1 to 20 carbon atoms Alkyl group ( For example, methyl, ethyl, cyclohexyl, trifluoromethyl, 2-hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl, 2-ethoxyethyl, benzyl, 4-carboxybenzyl, 2-diethylaminoethyl), carbon number 2-20 Alkenyl group (for example, vinyl, allyl), C1-C20 alkoxy group (for example, methoxy, ethoxy, butoxy), halogen atom (for example, F1, Cl, Br), C0-20 amino group (for example, unsubstituted) Amino group, dimethylamino, diethylamino, carboxyethylamino), C2-C20 alkoxycarbonyl group (for example, methoxycarbonyl), C1-C20 amide group (for example, acetamide, benzamide, 4-chlorobenzamide), carbon number 1 to 20 carbamoyl groups (eg unsubstituted Rubamoyl, methylcarbamoyl, phenylcarbamoyl, benzimidazol-2-onecarbamoyl), an aryl group having 6 to 20 carbon atoms (for example, phenyl, naphthyl, 4-carboxyphenyl, 4-methanesulfonamidophenyl, 3-benzoylaminophenyl), C6-C20 aryloxy group (for example, phenoxy, 3-methylphenoxy, naphthoxy), C1-C20 alkylthio group (for example, methylthio, octylthio), C6-C20 arylthio group (for example, phenylthio, naphthylthio) An acyl group having 1 to 20 carbon atoms (for example, acetyl, benzoyl, 4-chlorobenzoyl), a sulfonyl group having 1 to 20 carbon atoms (for example, methanesulfonyl, benzenesulfonyl), a ureido group having 1 to 20 carbon atoms (for example, methylureido) Phenylureido), an alkoxycarbonylamino group having 2 to 20 carbon atoms (for example, methoxycarbonylamino, hexyloxycarbonylamino), a cyano group, a hydroxyl group, a nitro group, a heterocyclic group (for example, a 5-ethoxycarbonylbenzoxazole ring as a heterocyclic ring, Pyridine ring, sulfolane ring, furan ring, pyrrole ring, pyrrolidine ring, morpholine ring, piperazine ring, pyrimidine ring, phthalimide ring, tetrachlorophthalimide ring, benzoisoquinoline dione ring).

In the formula (II), R ² is a hydrogen atom, an aliphatic group or an aromatic group. The definition of the aliphatic group and the aromatic group is 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 more preferably a hydrogen atom. Most preferred.

In the formula (II), R ³ and R ⁴ are each independently a hydrogen atom, a halogen atom, an aliphatic group, an aromatic group, —NR ⁶ R ⁷ , —OR ⁶ or —SR ⁷ . R ⁶ and R ⁷ are each independently a hydrogen atom, an aliphatic group or an aromatic group. The definition of the aliphatic group and the aromatic group is as described above. R ³ and R ⁴ are preferably a hydrogen atom or an aliphatic group, more preferably a hydrogen atom, an alkyl group, a substituted alkyl group, an aralkyl group or a substituted aralkyl group, and a hydrogen atom, an alkyl group or an aralkyl group. Is more preferable, and a hydrogen atom is most preferable.

In the formula (II), 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 is particularly preferably a substituted alkyl group having the same definition as —CHR ¹ R ² .

In formula (II), L ¹ , L ² and L ³ are each independently an optionally substituted methine. Examples of the methine substituent include a halogen atom, an aliphatic group, and an aromatic group. The definition of the aliphatic group and the aromatic group is as described above. A methine substituent may be bonded to form an unsaturated aliphatic ring or an unsaturated heterocyclic ring. An unsaturated aliphatic ring is preferred to an unsaturated heterocyclic ring. The ring to be formed is preferably a 6-membered ring or a 7-membered ring, and more preferably a cycloheptene ring or a cyclohexene ring. It is particularly preferred that the methine is unsubstituted or forms a cycloheptene ring or a cyclohexene ring.

In the formula (II), Z ¹ and Z ² are each an atomic group that independently forms a 5-membered or 6-membered nitrogen-containing heterocycle. 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. A 5-membered ring is preferred over a 6-membered ring. The nitrogen-containing heterocycle may be condensed with an aromatic ring (benzene ring or naphthalene ring). The nitrogen-containing heterocycle and its condensed ring may have a substituent. Substituents are as defined above. In the formula (II), m is 0, 1, 2 or 3.

The cyanine dye represented by the formula (II) is preferably used after forming a salt with an anion. When the cyanine dye represented by the formula (II) has an anionic group such as carboxyl or sulfo as a substituent, the dye can form an inner salt. In other cases, the cyanine dye preferably forms a salt with an anion outside the molecule. The anion is preferably monovalent or divalent, and more preferably monovalent. Examples of anions include halogen ions (Cl ⁻ , Br ⁻ , I ⁻ ), p-toluenesulfonate ions, ethyl sulfate ions, 1,5-disulfonaphthalene dianions, PF ₆ ⁻ , BF ₄ ⁻ and ClO ₄ ^−. Is included. A preferred cyanine dye is represented by the following formula (IIa).

In the formula (IIa), R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ , L ²¹ , L ²² , L ²³ and m ₁ are R ¹ , R ² , R ³ , R ⁴ in the formula (II), respectively. , R ⁵ , L ¹ , L ² , L ³ and m have the same definition.

In the formula (IIa), Y ²¹ and Y ²² are each independently —CR ²⁶ R ²⁷ , —NR ²⁶ —, —O—, —S— or —Se—. R ²⁶ and R ²⁷ are each independently a hydrogen atom or an aliphatic group, and may be bonded to each other to form a ring. The aliphatic group is particularly preferably an alkyl group or a substituted alkyl group.

In the formula (IIa), the benzene rings Z ²¹ and Z ²² may be condensed with other benzene rings. The benzene rings Z ²¹ and Z ²² and their condensed rings may have a substituent. Substituents are as defined above.

In the formula (IIa), m ₁ is 0, 1, 2, or 3. The cyanine dye represented by the formula (IIa) is preferably used after forming a salt with an anion. The salt formation is as described in formula (II).

  Specific examples of the dye are shown below, but are not limited thereto.

  The above dyes and other cyanine dyes can be synthesized by referring to the methods described in JP-A-62-123454 and JP-A-7-333784.

[Synthesis Example 1]
Synthesis of cyanine dye (1) A mixture of 33.4 g of ethyl bromoacetate, 15.9 g of 2,3,3-trimethylindolenine and 30 ml of ethanol was heated to reflux for 5 hours. After completion of the reaction, 50 ml of acetone and 500 ml of ethyl acetate were added, and the precipitated quaternary salt was separated by filtration. The yield of quaternary salt was 25.4 g, and the melting point was 250 ° C. or higher.

A mixed solution of 16.3 g of quaternary salt, 4.9 g of tetramethoxypropane, 75 g of N-methylpyrrolidone, 2.85 g of acetic acid and 19.0 g of acetic anhydride was heated at 50 ° C. for 3 hours. After completion of the reaction, 50 ml of water was added and the precipitated crystals were filtered off and recrystallized from methanol / isopropanol / ethyl acetate. The yield was 13.1 g, the melting point was 250 ° C. or higher, λmax was 637.5 nm, and ε was 2.16 × 10 ⁵ (methanol).

The base-bleachable dye of the present invention (including salts thereof, hereinafter also referred to as a decoloring dye) is a compound that can be decolored by the action of a base under heating conditions. When such dyes exerts a base under heating to dye substantially colorless 5 or 7-membered ring compound formed to ones mentioned are for example the above-mentioned formula (II) by an intramolecular nucleophilic reaction CHR ¹ A 5- or 7-membered ring compound is formed by R ² , CR ³ , and CR ⁴ , and the conjugation is lost, resulting in a substantially colorless compound.

  The 5- or 7-membered ring compound that is formed is a substantially colorless and stable compound that returns to the original dye and there is no problem that the decolored material is recolored.

  There are various types of base precursors that can be used in the present invention. Since the decoloring reaction is carried out under heating conditions, it is preferable to use a type of precursor that generates (or releases) a base by heating. A typical base precursor that generates a base by heating is a thermal decomposition (decarboxylation type) base precursor comprising a salt of a carboxylic acid and a base. When the decarboxylated base precursor is heated, the carboxyl group of the carboxylic acid undergoes a decarboxylation reaction, and the organic base is released. As the carboxylic acid, sulfonylacetic acid or propiolic acid which is easily decarboxylated is used. The sulfonylacetic acid and propiolic acid preferably have, as a substituent, a group having an aromaticity that promotes decarboxylation (an aryl group or an unsaturated heterocyclic group). The base precursor of sulfonyl acetate is described in JP-A-59-168441, and the base precursor of propiolate is described in JP-A-59-180537.

  The base component of the decarboxylation type base precursor is preferably an organic base, more preferably amidine, guanidine or a derivative thereof. The organic base is preferably a diacid base, a triacid base or a tetraacid base, more preferably a diacid base, and most preferably a diacid base of an amidine derivative or a guanidine derivative.

  The diacid base, triacid base or tetraacid base precursor of the amidine derivative is described in JP-B-7-59545. The diacid base, triacid base or tetraacid base precursor of the guanidine derivative is described in JP-B-8-10321.

  The diacid base of an amidine derivative or guanidine derivative comprises (A) two amidine or guanidine moieties, (B) a substituent of the amidine or guanidine moiety, and (C) a divalent linking two amidine or guanidine moieties. Consists of a linking group. Examples of the substituent of (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 heterocycle. The linking group (C) is preferably an alkylene group or a phenylene group.

  Examples of diacid base precursors of amidine derivatives or guanidine derivatives are shown below.

  The use amount (mol) of the base precursor is preferably 1 to 100 times, more preferably 3 to 30 times the use amount (mol) of the decoloring dye. The decoloring dye can be used for various applications by utilizing the decoloring reaction as described above. For example, a solution of a decolorizable dye and a base precursor can be used as a heat decolorable ink. Moreover, what apply | coated the solution of a decoloring dye and a base precursor to the transparent support body can also be used as a heat decoloring type | mold sheet | seat (filter).

  Further, the decolorizable dye and the base precursor can be applied to a heat decolorable recording material. The thermally decolorable recording material has a recording layer on a support (preferably a transparent support). The decolorizing dye is dispersed in the recording layer in the form of molecular or solid fine particles. When dispersed in a molecular form, a decolorizing dye solution is added to the recording layer coating solution. When dispersed in the form of solid fine particles, a dispersion of solid fine particles of a decoloring dye is added to the recording layer coating solution. 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, dextran, polyacrylamide) is preferably used.

  In the present invention, a decolorizing dye and a base precursor are added to the non-photosensitive layer of the photothermographic material so that the non-photosensitive layer functions as a filter layer or an antihalation layer. The photothermographic material generally has a non-photosensitive layer in addition to the photosensitive layer. The non-photosensitive layer is composed of (1) a protective layer provided on the photosensitive layer (on the side farther from the support), and (2) a plurality of photosensitive layers or between the photosensitive layer and the protective layer. It can be classified into an intermediate layer provided between them, (3) 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). In the present invention, the embodiment (4) is particularly preferable.

  The decolorizable dye and the base precursor (and melting point depressant) are preferably added to the same non-photosensitive layer. However, it may be added separately to two adjacent non-photosensitive layers. A barrier layer may be provided between the two non-photosensitive layers. In the present specification, “a layer contains a decoloring dye and a base precursor (and a melting point depressant)” means that there are a plurality of “layers”, that is, a plurality of layers separately contain a decoloring dye and a base precursor. This includes the case of adjacent layers. In the present invention, an adjacent layer is also used via a barrier layer.

  As a method of adding the decoloring dye to the non-photosensitive layer, a method of adding a solution, an emulsion, a solid fine particle dispersion, or a polymer impregnated product to the coating solution for the non-photosensitive layer can be employed. Moreover, you may add dye to a non-photosensitive layer using a polymer mordant. These addition methods are the same as the method of adding a dye to a normal photothermographic material. The latex used for the polymer impregnation is described in U.S. Pat. No. 4,199,363, West German Patent Publication Nos. 25141274, 2541230, European Patent Publication No. 0291104, and Japanese Patent Publication No. 53-41091. An emulsification method in which a dye is added to a solution in which a polymer is dissolved is described in International Publication No. 88/00723.

The amount of decoloring dye added is determined by the use of the dye. In general, the optical density (absorbance) measured at the target wavelength is used in an amount exceeding 0.1. The optical density is preferably 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 in} terms of the coating amount per 1 m ² of the light-sensitive material. Preferably, it is about 0.005 to 0.8 g / m ² , particularly preferably about 0.01 to 0.2 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 kinds of decoloring dyes may be used in combination in a heat decoloring type recording material or a photothermographic material. Similarly, two or more kinds of base precursors may be used in combination.

  Hereinafter, the photothermographic material will be further described. The photothermographic material is preferably a mono-sheet 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 a photosensitive silver halide (a catalytically active amount of photocatalyst) and preferably a reducing agent, and a non-photosensitive layer. The photosensitive layer further contains a binder (generally a synthetic polymer), preferably an organic silver salt (a reducible silver source). Furthermore, it is preferable to contain a hydrazine compound (super high contrast agent) and a color tone adjusting agent (controlling the color tone of silver). A plurality of photosensitive layers may be provided. For example, a high-sensitivity photosensitive layer and a low-sensitivity photosensitive layer can be provided in the photothermographic material for the purpose of adjusting 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 (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-described layer containing a dye, that is, a filter layer or an antihalation layer.

  Supports for photothermographic materials include paper, polyethylene-coated paper, polypropylene-coated paper, parchment, cloth, metal (eg, aluminum, copper, magnesium, zinc) sheets or thin films, glass, metal (eg, Glass and plastic films coated with chromium alloy, steel, silver, gold, platinum). Examples of plastics used for the support include polyalkyl methacrylate (eg, polymethyl methacrylate), polyester (eg, polyethylene terephthalate PET), 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 the polymer include polyvinylidene chloride, acrylic acid-based polymers (eg, polyacrylonitrile, methyl acrylate), unsaturated dicarboxylic acid (eg, itaconic acid, acrylic acid) polymers, carboxymethyl cellulose, and polyacrylamide. Copolymers may be used. Instead of coating with a polymer, an undercoat layer containing the 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.

The addition amount of silver halide is preferably 0.03 to 0.6 g / m ² , more preferably 0.05 to 0.4 g / m ² , and 0.1 to 0.4 g / m 2. ² is most preferred.

  The silver halide is generally prepared as a silver halide emulsion by reaction of silver nitrate and a soluble halogen salt. However, the soap may be prepared by reacting silver soap with halogen ions and converting the soap part of the silver soap to halogen. Moreover, you may add a halogen ion at the time of formation of silver soap.

  As the reducing agent, phenidone, hydroquinones, catechol and hindered phenol are preferable. The reducing agents are described in U.S. Pat. Nos. 3,770,448, 3,773,512, 3,593,863 and 4,460,681, and Research Disclosure 17029, 2,963.

  Examples of reducing agents include aminohydroxycycloalkenone compounds (eg, 2-hydroxy-piperidino-2-cyclohexenone), N-hydroxyurea derivatives (eg, Np-methylphenyl-N-hydroxyurea), aldehydes or Ketone hydrazones (eg, anthracene aldehyde phenylhydrazone), phosphoramidophenols, phosphoramidoanilines, polyhydroxybenzenes (eg, hydroquinone, t-butyl-hydroquinone, isopropylhydroquinone, 2,5-dihydroxy-phenyl) Methylsulfone), 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), amidoxins, azines (eg, aliphatic carboxylic acid arylhydrazides) and ascorbic acid A combination of polyhydroxybenzene and hydroxylamine, reductone, hydrazine, hydroxamic acids, a combination of azines and sulfonamidophenols, α-cyanophenylacetic acid derivatives, bis-β-naphthol and 1,3-dihydroxy Combination with benzene derivatives, 5-pyrazolones, sulfonamidophenols, 2-phenylindane-1,3-dione, chroman, 1,4-dihydropyridines (eg, 2,6-dimethoxy-3,5-dicarbo) Ethoxy-1,4-di Dropyridine), bisphenols (eg, bis (2-hydroxy-3-tert-butyl-5-methylphenyl) methane, bis (6-hydroxy-m-tri) mesitol, 2,2-bis (4-hydroxy-3) -Methylphenyl) propane, 4,4-ethylidene-bis (2-tert-butyl-6-methyl) phenol), UV-sensitive ascorbic acid derivatives and 3-pyrazolidones.

  An ester of an amino reductone functioning as a reducing agent precursor (eg, piperidinohexose reductone monoacetate) may be used as the reducing agent. A particularly preferred reducing agent is hindered phenol.

The addition amount of the reducing agent is preferably from 0.01~5.0g / m ^2, and more preferably 0.1 to 3.0 g / m ^2.

  The photosensitive layer and the non-photosensitive layer preferably contain a binder. As the binder, generally a colorless transparent or translucent polymer is used. Although natural or semi-synthetic polymers (eg, gelatin, gum arabic, hydroxyethyl cellulose, cellulose ester, casein, starch) can be used, in view of heat resistance, synthetic polymers are preferable to natural or semi-synthetic polymers. However, cellulose esters (eg, acetate, cellulose acetate butyrate) are relatively heat resistant even if they are semi-synthetic polymers, and are preferably used as binders for photothermographic materials.

  Examples of synthetic polymers include polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, polymethyl methacrylate, polyvinyl chloride, polymethacrylic acid, styrene / maleic anhydride copolymer, styrene / 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. Accordingly, styrene / acrylonitrile copolymers, styrene / butadiene copolymers, polyvinyl acetals, polyesters, polyurethanes, loose acetate butyrate, polyacrylic acid, polymethyl methacrylate, polyvinyl chloride and polyurethanes are preferred, and styrene / butadiene copolymers and polyvinyl acetals are more preferred. .

  The binder is used after being dissolved or emulsified in the solvent (water or organic solvent) of the coating solution for the photosensitive layer or the non-photosensitive layer. When the binder is emulsified in the coating solution, an emulsion of the binder may be mixed with the coating solution.

As a binder used for the photosensitive layer, it is preferable to apply a polymer latex with an aqueous coating solvent. The amount of binder used in the photosensitive layer is preferably in the range of 0.2 to 30 g / m ² , more preferably 1 to 15 g / m ² .

  The amount of binder used in the layer containing the decoloring dye is preferably adjusted so that the amount of the decoloring dye applied is 0.1 to 60 wt% of the binder. The decolorizable dye is preferably 0.2 to 30% by weight, and most preferably 0.5 to 10% by weight of the binder.

  It is preferable that the photosensitive layer or the non-photosensitive layer further contains an organic silver salt. The organic acid that forms the silver salt is preferably a long-chain fatty acid. The number of carbon atoms in the fatty acid is preferably 10 to 30, and more preferably 15 to 25. An organic silver salt complex may be used. The ligand of the complex preferably has a total stability constant with respect to silver ions in the range of 4.0 to 10.0. The organic silver salt is described in Research Disclosure Nos. 17029 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), carboxyalkylthiourea (eg, 1- (3-carboxypropyl) thiourea , 1- (3-carboxypropyl) -3,3-dimethylthiourea) silver salt, silver complex of a polymer reaction product of aldehyde (eg, formaldehyde, acetaldehyde, butyraldehyde) and hydroxy-substituted aromatic carboxylic acid, aromatic Silver salts of carboxylic acids (eg, salicylic acid, benzoic acid, 3,5-dihydroxybenzoic acid, 5,5-thiodisalicylic acid), thioenes (eg, 3- (2-carboxyethyl) -4-hydroxymethyl- Silver salt or silver complex of 4-thiazoline-2-thioene, 3-carboxymethyl-4-thiazoline-2-thioene), nitrogen acid ( , Imidazole, pyrazole, urazole, 1,2,4-thiazole, 1H-tetrazole, 3-amino-5-benzylthio-1,2,4-triazole, benzotriazole) silver salt or silver complex, silver salt of saccharin, Silver salts of 5-chlorosalicylaldoxime and silver salts of mercaptides are included. Silver behenate is most preferred. The organic silver salt is preferably used in 0.05 g / m ² or more 3 g / m ² or less as the amount of silver, and more preferably used in 0.3 g / m ² or more 2 g / m ² or less.

  It is preferable that the photosensitive layer or the non-photosensitive layer further contains an ultrahigh contrast agent. When the 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. The reproducibility of a dot image or a line image can be improved by using a super-high contrast agent. As the ultra-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.

The hydrazine compound includes hydrazine (H ₂ N—NH ₂ ) and a compound in which at least one of its hydrogen atoms is substituted. In the substituent, an aliphatic group, an aromatic group or a heterocyclic group is directly bonded to the nitrogen atom of hydrazine, or an aliphatic group, an aromatic group or a heterocyclic group is bonded to the nitrogen atom of hydrazine through a linking group. . Examples of the linking group include —CO—, —CS—, —SO ₂ —, —POR— (R is an aliphatic group, aromatic group or heterocyclic group), —CNH—, and combinations thereof.

  As for the hydrazine compound, US Pat. Nos. 5,464,738, 5,496,695, 5,512,411, 5,536,622, JP-B-6-77138, JP-A-6-93082, JP-A-6-230497, JP-A-6-289520 No. 6-313951, No. 7-5610, No. 7-77783, No. 7-104426.

  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. Moreover, you may emulsify the solution which melt | dissolved the hydrazine compound in the oil-based (auxiliary) solvent in the coating liquid. Examples of oily (co-) solvents include dibutyl phthalate, tricresyl phosphate, glyceryl triacetate, diethyl phthalate, ethyl acetate and cyclohexanone. Furthermore, you may add the solid dispersion of a hydrazine compound to a coating liquid. The dispersion of the hydrazine compound can be carried out using a known disperser such as a ball mill, a colloid mill, a manton goring, a microfluidizer or an ultrasonic disperser.

The addition amount of the ultrahigh contrast agent is preferably 1 × 10 ^{−6 to} 1 × 10 ⁻² mol, preferably 1 × 10 ^{−5 to} 5 × 10 ⁻³ mol, relative to 1 mol of silver halide. More preferably, it is 2 × 10 ^{−5 to} 5 × 10 ⁻³ mol.

  In addition to the ultrahigh contrast agent, a high contrast accelerator may be used. Examples of the contrast accelerator include amine compounds (described in US Pat. No. 5,545,505), hydroxamic acid (described in US Pat. No. 5,545,507), acrylonitriles (described in US Pat. No. 5,545,507), and hydrazine compounds (US Pat. No. 5558983).

  It is preferable that the photosensitive layer or the non-photosensitive layer further contains a color tone adjusting agent. The color tone adjusting agent is described in Research Disclosure No. 17029.

  Examples of the color adjusting agent include imides (eg, phthalimide), cyclic imides (eg, succinimide), pyrazolin-5-ones (eg, 3-phenyl-2-pyrazolin-5-one, 1-phenyluranium). Sol), quinazolinones (eg, quinazoline, 2,4-thiazolidinedione), naphthalimides (eg, N-hydroxy-1,8-naphthalimide), cobalt complexes (eg, cobalt hexamine trifluoroacetate), mercaptans ( Examples, 3-mercapto-1,2,4-triazole), N- (aminomethyl) aryl dicarboximides (eg, N- (dimethylaminomethyl) phthalimide), blocked pyrazoles (eg, N, N 'Hexamethylene-1-carbamoyl-3,5-dimethylpyrazole), isothiuronium ) Derivatives (eg, 1,8- (3,6-dioxaoctane) bis (isothiuronium trifluoroacetate) and photobleaching agents (eg, 2- (tribromomethylsulfonyl) benzothiazole), merocyanine Dyes (eg, 3-ethyl-5-((3-ethyl-2-benzothiazolinylidene) -1-methylethylidene) -2-thio-2,4-oxazolidinedione), phthalazinone Compounds and metal salts thereof (eg, phthalazinone, 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxyphthalazinone, 2,3-dihydro-1,4-phthalazinedione, 8 -Methylphthalazinone), a combination of a phthalazinone compound and a sulfinic acid derivative (eg, sodium benzenesulfinate) Combinations of phthalazinone compounds and sulfonic acid derivatives (eg, sodium p-toluenesulfonate), phthalazine and derivatives thereof (eg, phthalazine, 6-isopropylphthalazine, 6-methylphthalazine), combinations of phthalazines and 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, tetrachlorophthalic anhydride), quinazolinediones, benzoxazines, naltoxazine derivatives, benzoxazine-2,4-diones (eg, 1,3-benzoxazine-2,4-dione) ), Pyrimidines, asymmetric-triazines (for example, 2,4-dihydroxypyrimidine), tetraazapentalene derivatives (eg, 3,6-dimethylocapto-1,4-diphenyl-1H, 4H-2,3a, 5,6a-tetraazapentalene). . Phthalazines are particularly preferred.

  The toning agent is preferably contained in the surface of the image forming layer in an amount of 0.1 to 50 mol% per mol of silver, and more preferably 0.5 to 20 mol%.

  An antifoggant may be added to the photosensitive layer or the non-photosensitive layer (preferably the photosensitive layer). Antifoggants include non-mercury compounds (US Pat. Nos. 3,874,946, 4,45,075, 4,425,885, 4,475,999, 5,028,523, and British Patent Application No. 9221383, rather than mercury compounds (described in US Pat. No. 3,589,903). No. 4, No. 9300147.7, No. 93111790.1, JP-A-59-57234, JP-B-55-12581, JP-A-53-32015, JP-A-63-292125 ) Is preferably used.

  Particularly preferred antifoggants are heterocyclic compounds having a halogen (F, Cl, Br, I) substituted methyl group.

  Silver halide is generally used after spectral sensitization. As for spectral sensitizing dyes, JP-A-60-140335, JP-A-63-159841, JP-A-63-231437, JP-A-63-259651, JP-A-63-304242, and JP-A-63-15245, US Patents. Nos. 4639414, 4740455, 4471966, 475175, and 483596.

  A surfactant, antioxidant, stabilizer, plasticizer, ultraviolet absorber or coating aid may be further added to the photothermographic material. Various additives are added to either the photosensitive layer or the non-photosensitive layer.

  Techniques (including the above-mentioned silver halide grains, organic silver salts, reducing agents, binders, etc.) that can be used for the photothermographic material of the present invention include EP803764A1, EP883022A1, WO98 / 36322, and JP-A-9 -281637, 9-297367, 9-304869, 9-311405, 9-329865, 10-10669, 10-62899, 10-69023, 10-186568 10-90823, 10-171063, 10-186565, 10-186567, 10-186569, 10-186570, 10-186571, 10-186572, 10-197974, 10-197982, 10-197983, 10-197985, 10-197986, 10-197987, 10-207001, 10-207004, 10 -221807, 10-282601, 10-288823, 10-288824, 10-307365, 10-312038, 10-339934, 11-7100, 11-15105 No. 11-24200, No. 11-24201, No. 11-30832.

  The photothermographic material forms an image by heating after image exposure. By this heat development, a black silver image is formed. Image exposure is preferably performed using a laser. The heating temperature for the heat development is preferably 80 to 250 ° C, more preferably 100 to 200 ° C. The heating time is generally 1 second to 2 minutes.

  A plate heater method is preferred as the heat development method. The heat development method using the plate heater method is a method described in Japanese Patent Application Nos. 9-229684 and 10-177610, and a photothermographic material having a latent image formed thereon is brought into contact with a heating means in a heat developing unit. A heat developing device that obtains a visible image by causing the heating means to be a plate heater, and a plurality of pressing rollers are arranged to face each other along one surface of the plate heater; The photothermographic apparatus performs thermal development by passing the photothermographic material between the plate heater and the plate heater.

  Examples of the heating method in the heat development process include forms as shown in FIGS.

  The photothermographic material conveyed to the image exposure unit is exposed by a laser beam or the like scanned with a light beam to form a latent image on the photothermographic material, and then conveyed to the heat developing unit 18 by a conveyance roller or the like. The At this time, the dust on the back surface and the front surface of the photothermographic material is removed by a dust removing roller.

  The heat development unit 18 is a part that heat-develops the photothermographic material to perform heat development to convert the latent image into a visible image. As shown in FIG. A plurality of presser rollers 122 arranged to face the plate heater 120 are provided.

  The plate heater 120 is a plate-like heating member in which a heating element such as a nichrome wire is laid and accommodated in a plane, and is maintained at the developing temperature of the photothermographic material. The surface of the plate heater 120 is preferably coated with a fluororesin or a fluororesin sheet for the purpose of reducing frictional resistance or imparting abrasion resistance.

  Further, in the photothermographic material, a volatile component is evaporated by heating during the heat development, and accordingly, the photothermographic material floats up from the plate heater 120, and the contact between the photothermographic material A and the plate heater 120 becomes non-uniform. There is. Therefore, it is also preferable to form minute irregularities on the surface of the plate heater 120 in order to release this vapor.

  In order to compensate for a temperature drop due to heat radiation at both ends of the plate heater 120, it is preferable to provide a temperature gradient so that the temperatures at both ends are higher than those at the other portions.

  The presser rollers 122 are arranged at a predetermined pitch over the entire length of the plate heater 120 in the conveying direction, in contact with one surface of the plate heater 120 or at intervals equal to or less than the thickness of the photothermographic material. The plate heater 120 forms a photothermographic material conveyance path. By spacing the photothermographic material conveyance path below the thickness of the photothermographic material, buckling of the photothermographic material can be prevented. At both ends of the photothermographic material conveyance path, a supply roller pair 126 for supplying the photothermographic material to the heat developing unit 18 from the direction indicated by the arrow and a discharge roller pair for discharging the photothermographic material in the direction indicated by the arrow after the heat development. 128 is arranged.

  Further, it is preferable to provide a heat insulation cover 125 for heat insulation on the side of the press roller 122 opposite to the plate heater 120.

  When the photothermographic material is transported, if the leading end of the photothermographic material hits the presser roller 122, the photothermographic material stops for a moment. At this time, if the presser rollers 122 are spaced apart at an equal pitch, the same portion of the photothermographic material stops for each presser roller 122 and that portion is pressed against the plate heater 120 for a long time. As a result, the photothermographic material has streaky development unevenness extending in the width direction. Therefore, it is preferable to make the pitch of the pressing rollers 122 non-uniform.

  Further, as shown in FIG. 2, a driving roller 130 having an envelope surface of each presser roller 122 as a peripheral surface is installed in contact with each presser roller 122, and each presser roller 122 is rotated by turning the drive roller 130. It can also be configured.

  In the above description, the plate heater 120 includes a configuration in which a plate member made of a heat conductor and a heat source are arranged on the opposite side of the plate member to the heating surface of the photothermographic material.

Specific examples of the present invention are shown below.
Example 1
(Preparation of silver halide emulsion 1)
Add 6.7cc of 1wt% potassium bromide solution to 1421cc of distilled water, and further add 8.2cc of 1N nitric acid and 21.8g of phthalated gelatin. The solution A was prepared by adding distilled water to 37.04 g of silver nitrate and diluting to 159 cc, and solution B having 32.6 g of potassium bromide diluted to 200 cc with distilled water, and maintaining the pAg at 8.1 by the control double jet method. While adding the whole amount of the solution A at a constant flow rate over 1 minute. (Solution B was added by the controlled double jet method) Thereafter, 30 cc of a 3.5 wt% aqueous hydrogen peroxide solution was added, and 36 cc of a 3 wt% aqueous solution of Compound 1 was further added. After that, the solution A is diluted again with distilled water to 317.5 cc and the compound 2 is dissolved in the solution B so that the final amount is 1 × 10 ⁻⁴ mol per mol of silver. Using the solution B2 diluted with distilled water to 400 cc, which is twice that of B, the total amount of the solution A2 was added over 10 minutes at a constant flow rate while maintaining the pAg at 8.1 by the controlled double jet method. (Solution B2 is added by the controlled double jet method) After that, 50cc of 0.5wt% methanol solution of Compound 3 is added, and pAg is lowered to 7.5 with silver nitrate, and then the pH is adjusted to 3.8 with 1N sulfuric acid. , Stop stirring, perform precipitation / desalting / washing steps, add 3.5 g of deionized gelatin, add 1N sodium hydroxide, adjust to pH 6.0, pAg 8.2 to obtain a silver halide dispersion. Created.

  The resulting grains in the silver halide emulsion were pure silver bromide grains having an average sphere equivalent diameter of 0.05 μm and a sphere equivalent diameter variation coefficient of 18%. The particle size and the like were obtained from an average of 1000 particles using an electron microscope. The [100] face ratio of the particles was determined to be 85% using the Kubelka-Munk method.

The emulsion was heated to 50 ° C. with stirring, compound 0.5 wt% solution of 4 plus 3.5 wt% solution 5cc of Compound 5 and 5cc and 3 × 10 Compound 6 after 1 minute per mol of silver ^{- 5} mol was added. After an additional 2 minutes, per mol of silver solid dispersion of the spectral sensitizing dye A (aqueous gelatin solution), 5 × 10 ^-3 mols, silver further 2 minutes after tellurium sensitizer B 1 mole per 5 × 10 ^{- 5} mol was added and aged for 50 minutes. At the end of ripening, 1 × 10 ⁻³ mole of Compound 3 was added per mole of silver to lower the temperature, the chemical sensitization was finished, and silver halide emulsion 1 was prepared.

(Preparation of silver halide emulsion 2)
After dissolving 22 g of phthalated gelatin and 30 mg of potassium bromide in 700 ml of water and adjusting the pH to 5.0 at a temperature of 40 ° C., 159 ml of an aqueous solution containing 18.6 g of silver nitrate and an aqueous solution of potassium bromide are kept at pAg 7.7. However, it was added over 10 minutes by the controlled double jet method. Next, an aqueous solution containing 476 ml of an aqueous solution containing 55.4 g of silver nitrate, 8 μmol / liter of dipotassium hexachloroiridate and 1 mol / liter of potassium bromide is maintained for 30 minutes by the controlled double jet method while maintaining pAg of 7.7. Added over time. Thereafter, the pH was lowered to cause aggregation and sedimentation, followed by desalting. Thereafter, 0.1 g of phenoxyethanol was added to adjust the pH to 5.9 and pAg 8.0 to complete the formation of silver bromide grains. The obtained silver halide grains A were cubic grains having an average grain size of 0.07 μm, a coefficient of variation in projected area diameter of 8%, and a (100) plane ratio of 86%.

The temperature was raised to 60 ° C. with respect to the prepared silver halide grains A, 85 μmol of sodium thiosulfate per 1 mol of silver, 11 μmol of 2,3,4,5,6-pentafluorophenyldiphenylphosphine selenide, Tellurium sensitizer B 2 μmol, chloroauric acid 3.3 μmol and thiocyanic acid 230 μmol were added and aged for 120 minutes, then changed to 40 ° C. to change spectral sensitizing dye A to silver halide by 3. 5 × 10 ⁻⁴ mol, 2-mercapto-5-methylbenzimidazole was added while stirring at 4.6 × 10 ⁻³ mol and stirred for 10 minutes, and then rapidly cooled to 25 ° C. to prepare silver halide emulsion 2. Ended.

(Preparation of organic silver salt dispersion)
Henkel behenic acid (trade name Edenor C22-85R) 43.8 g, distilled water 730 ml, tert-butanol 60 ml is stirred at 79 ° C., 1N sodium hydroxide aqueous solution 117 ml is added over 55 minutes and reacted for 240 minutes. It was. Next, 112.5 ml of an aqueous solution containing 19.2 g of silver nitrate was added over 45 seconds, left as it was for 20 minutes, and the temperature was lowered to 30 ° C. Thereafter, the solid content was filtered by suction filtration, and the solid content was washed with water until the conductivity of the filtrate reached 30 μS / cm. The solid content thus obtained was handled as a wet cake without drying, and 4 g of polyvinyl alcohol (trade name: PVA-205) and water were added to the wet cake corresponding to a dry solid content of 100 g, and the total amount was 385 g. Pre-dispersed with a mixer.

Next, the pre-dispersed stock solution is adjusted to a pressure of 1750 kg / cm ² of a disperser (trade name: Microfluidizer M-110S-EH, manufactured by Microfluidics International Corporation, using a G10Z interaction chamber). The silver behenate dispersion B was obtained by repeated processing. The silver behenate particles contained in the silver behenate dispersion thus obtained were needle-like particles having an average minor axis of 0.04 μm, an average major axis of 0.8 μm, and a variation count of 30%. The particle size was measured with MasterSizerX manufactured by Malvern Instruments Ltd. The cooling operation was set to a desired dispersion temperature by installing a serpentine heat exchanger before and after the interaction chamber and adjusting the temperature of the refrigerant.

(Preparation of 25 wt% dispersion of reducing agent)
176 g of water was added to 80 g of 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane and 64 g of a 20 wt% aqueous solution of modified polyvinyl alcohol poval MP203 manufactured by Kuraray Co., Ltd. Mix well to make a slurry. Then, 800 g of zirconia beads having an average diameter of 0.5 mm were prepared, put in a vessel together with the slurry, dispersed for 5 hours with a disperser (1/4 G sand grinder mill: manufactured by Imex Co., Ltd.), and reducing agent dispersed. A product was prepared. The reducing agent particles contained in the reducing agent dispersion thus obtained had an average particle size of 0.72 μm.

(Preparation of 20 wt% dispersion of mercapto compound)
224 g of water was added to 64 g of 3-mercapto-4-phenyl-5-heptyl-1,2,4-triazole and 32 g of a 20 wt% aqueous solution of modified polyvinyl alcohol poval MP203 manufactured by Kuraray Co., Ltd., and mixed well to form a slurry. . Thereafter, 800 g of zirconia beads having an average diameter of 0.5 mm were prepared and placed in a vessel together with the slurry, and dispersed for 10 hours with a dispersing machine (1 / 4G sand grinder mill: manufactured by IMEX Co., Ltd.) to disperse the mercapto compound. A product was prepared. The mercapto compound particles contained in the mercapto compound dispersion thus obtained had an average particle size of 0.67 μm.

(Preparation of 30 wt% dispersion of organic polyhalogen compound)
224 g of water was added to 48 g of 20% by weight aqueous solution of 48 g of tribromomethylphenyl sulfone, 48 g of tribromomethylsulfonyl-4-phenyl-5-tridecyl-1,2,4-triazole and Kuraray Co., Ltd. modified polyvinyl alcohol poval MP203. Mix well to make a slurry. Thereafter, 800 g of zirconia beads having an average diameter of 0.5 mm were prepared and placed in a vessel together with the slurry, and dispersed for 5 hours with a disperser (1/4 G sand grinder mill: manufactured by IMEX Co., Ltd.), and an organic polyhalogen compound A dispersion was prepared. The organic polyhalogen compound particles contained in the organic polyhalogen compound dispersion thus obtained had an average particle size of 0.74 μm.

(Preparation of 10 wt% methanol solution of phthalazine compound)
10 g of 6-isopropylphthalazine was dissolved in 90 g of methanol and used.

(Preparation of 20 wt% dispersion of pigment)
C. I. 250 g of water was added to 64 g of Pigment Blue 60 and 6.4 g of DEMOL N manufactured by Kao Corp. and mixed well to prepare a slurry. Thereafter, 800 g of zirconia beads having an average diameter of 0.5 mm are prepared, put in a vessel together with the slurry, and dispersed for 25 hours with a disperser (1/4 G sand grinder mill: manufactured by Imex Co., Ltd.), to obtain a pigment dispersion Was prepared. The pigment particles contained in the pigment dispersion thus obtained had an average particle size of 0.21 μm.

(Preparation of 40 wt% SBR latex)
The following SBR latex diluted 10-fold with distilled water was diluted with an ultrafiltration purification module FS03-FC-FUY03A1 (Daisen Membrane System Co., Ltd.) until the ionic conductivity reached 1.5 mS / cm. The purified product was used. At this time, the latex concentration was 40 wt%.

SBR latex: -St (68) -Bu (29) -AA (3) -latex average particle size 0.1 [mu] m
Equilibrium water content of polymer (25 ° C 60% RH) 0.6wt%
Concentration 45wt%
Ionic conductivity 4.2mS / cm
pH 8.2

  The ion conductivity was measured using a conductivity meter CM-30S manufactured by Toa Denpa Kogyo Co., Ltd., and the latex stock solution (40 wt%) was measured at 25 ° C.

(Preparation of emulsion layer coating solution)
(Emulsion layer coating solution)
103 g of the organic acid silver salt dispersion obtained above, 5 g of a 20 wt% aqueous solution of polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.), 23.2 g of the 25% reducing agent dispersion, and 30 wt% of the organic polyhalogen compound dispersion 11 0.5 g, 3.1 g of a mercapto compound 20 wt% dispersion, 106 g of the ultrafiltered SBR latex 40 wt%, 16 ml of a 10 wt% solution of a phthalazine compound, 0.8 g of a 20 wt% dispersion of the above pigment, silver halide emulsion 1 5 g and 5 g of silver halide emulsion 2 were mixed well to prepare an emulsion layer coating solution, which was coated at 70 ml / m ² .

  The viscosity of the coating solution was 85 [mPa · s] at 40 ° C. (No. 1 rotor) as measured with a B-type viscometer of Tokyo Keiki. The viscosity of the coating solution at 25 ° C. using an RFS fluid spectrometer manufactured by Rheometrics Far East Co., Ltd. is 1500, 220, 70, respectively at shear rates of 0.1, 1, 10, 100, 1000 [1 / sec]. 40, 20 [mPa · s].

(Preparation of intermediate layer coating solution)
800 g of 10 wt% aqueous solution of alkyl-modified polyvinyl alcohol MP203 (manufactured by Kuraray Co., Ltd.), 2-hydroxy-4- (methacryloyloxyethoxy) benzophenone / methyl methacrylate copolymer polymer latex type UV absorber (UVA-383MA manufactured by BASF) 200 g of (30 wt%) and 2 ml of a 5 wt% aqueous solution of Aerosol OT were added to form an intermediate layer coating solution, which was coated on the emulsion layer at 5 ml / m ² . The viscosity of the coating solution was 28 [mPa · s] at 40 ° C. (No. 1 rotor) with a B-type viscometer.

(Preparation of emulsion surface protective layer first layer coating solution)
(Protective layer first layer coating solution)
Dissolve 80g of inert gelatin in water, 64ml of 10wt% methanol solution of phthalic acid, 74ml of 10wt% aqueous solution of 4-methylphthalic acid, 28ml of 1N sulfuric acid, 5wt% aqueous solution of Aerosol OT (American Cyanamid) 5 ml was added, and water was added to a total amount of 1000 g to form a coating solution, which was coated on the intermediate layer so as to be 10 ml / m ² . The viscosity of the coating solution was 17 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor).

(Preparation of emulsion surface protective layer second layer coating solution)
(Protective layer second layer coating solution)
Dissolve 100 g of inert gelatin in water, 20 ml of 5 wt% solution of N-perfluorooctylsulfonyl-N-propylalanine potassium salt, 16 ml of 5 wt% solution of Aerosol OT (American Cyanamid), polymethyl Add 25 g of methacrylate fine particles (average particle size 4.0 μm), 1.4 g of phthalic acid, 1.6 g of 4-methylphthalic acid, 44 ml of 1N sulfuric acid, 445 ml of 4 wt% aqueous solution of chromium alum, and add water to a total amount of 2000 g. A surface protective layer coating solution was applied on the first protective layer so as to be 10 ml / m ² . The viscosity of the coating solution was 9 [mPa · s] at 40 ° C. (No. 1 rotor) with a B-type viscometer.

Support creation (1.PET support creation)
Using terephthalic acid and ethylene glycol, PET having an intrinsic viscosity of IV = 0.66 (measured in phenol / tetrachloroethane = 6/4 (weight ratio) at 25 ° C.) was obtained according to a conventional method. This is pelletized, dried at 130 ° C for 4 hours, melted at 300 ° C, extruded from a T-die, and then rapidly cooled to create an unstretched film with a thickness of 175 µm after heat setting. did.

This was stretched 3.3 times longitudinally using rolls with different peripheral speeds and then stretched 4.5 times transversely with a tenter. The temperatures at this time were 110 ° C. and 130 ° C., respectively. Thereafter, the film was heat-fixed at 240 ° C. for 20 seconds and relaxed by 4% in the lateral direction at the same temperature. Thereafter, the chuck portion of the tenter was slit and then knurled at both ends and wound at 4 kg / cm ² to obtain a roll having a thickness of 175 μm.

(2. Surface corona treatment)
Using a solid state corona treatment machine 6KVA model manufactured by Pillar, both surfaces of the support were treated at room temperature at 20 m / min. From the current and voltage readings at this time, it was found that the support was processed at 0.375 kV · A · min / m ² . The treatment frequency at this time was 9.6 kHz, and the gap clearance between the electrode and the dielectric roll was 1.6 mm.

(Preparation of undercoat coating solution A)
Polyester copolymer aqueous dispersion Pesresin A-515GB (30%, manufactured by Takamatsu Yushi Co., Ltd.) 200ml, polystyrene fine particles (average particle size 0.2μm) 1g, surfactant A (1wt%) 20ml, Distilled water was added to make 1000 ml, thereby preparing an undercoat coating solution A.

(Preparation of undercoat coating solution B)
200 ml of styrene-butadiene copolymer aqueous dispersion (styrene / butadiene / itaconic acid = 47/50/3 (weight ratio), concentration 30 wt%) and 1.1 g of polystyrene fine particles (average particle size 0.4 μm) are added to 680 ml of distilled water. Further, distilled water was added to make 1000 ml of the undercoat coating solution B.

(Preparation of undercoat coating solution C)
10 g of inert gelatin is dissolved in 500 ml of distilled water, and 40 g of an aqueous dispersion of tin oxide-antimony oxide composite fine particles (40 wt%) described in JP-A-61-20033 is added thereto. Was added to make 1000 ml to prepare an undercoat coating solution C.

(Create an undercoat support)
After the corona discharge treatment is performed on one surface (photosensitive surface) of the 175 μm thick biaxially stretched polyethylene terephthalate support, the undercoat coating solution A is applied with a bar coater so that the wet coating amount becomes 5 ml / m ^2. It was applied and dried at 180 ° C. for 5 minutes. The dry film thickness was about 0.3 μm.

Next, after corona discharge treatment was applied to the back surface (back surface), the undercoat coating solution B was applied with a bar coater so that the wet coating amount was 5 ml / m ² and the dry film thickness was about 0.3 μm. Dry for 5 minutes, and then apply the undercoat coating solution C on this with a bar coater so that the wet coating amount is 3 ml / m ² and the dry film thickness is about 0.03 μm, and dry at 180 ° C. for 5 minutes to support the undercoat. Created the body.

  (Preparation of Base Precursor Solid Fine Particle Dispersion (a)) 64 g of the following base precursor compound (7) [mp90 ° C.] and 10 g of the surfactant Demol N manufactured by Kao Corporation were mixed with 246 ml of distilled water. The beads were dispersed using a sand mill (1/4 Gallon sand grinder mill, manufactured by IMEX Co., Ltd.) to obtain a base precursor solid fine particle dispersion (a) having an average particle size of 0.2 μm.

(Preparation of solid fine particle dispersion (b) and (c) of base precursor)
64 g of base precursor compound (7) and 14 g of diphenylsulfone compound (8) [mp127 ° C] and 10 g of surfactant Demol N made by Kao Corporation were mixed with 220 ml of distilled water, and the mixture was mixed with a sand mill (1/4 Gallon sand A bead dispersion was performed using a grinder mill (manufactured by IMEX Co., Ltd.) to obtain a solid fine particle co-dispersion liquid (b) of a base precursor compound and a diphenyl sulfone compound having an average particle size of 0.2 μm, and a diphenyl sulfone compound (8 ) 28 g was used to obtain a similar co-dispersion liquid (c).

(Preparation of solid fine particle dispersion (d) and (e) of base precursor)
64 g of the base precursor compound (7) and 16 g of 4-chlorophenyl (phenyl) sulfone compound (9) [mp90 ° C.] 16 g and 10 g of the surfactant Demol N manufactured by Kao Corporation were mixed with 220 ml of distilled water. 1/4 Gallon Sand Grinder Mill (manufactured by Imex Co., Ltd.) and dispersed in beads, and an average particle size of 0.2 μm, a solid fine particle co-dispersed liquid of a base precursor compound and 4-chlorophenyl (phenyl) sulfone compound (d) Moreover, the same co-dispersion liquid (e) was obtained using 32 g of 4-chlorophenyl (phenyl) sulfone compounds (9).

(Preparation of dye solid fine particle dispersion)
9.6 g of the following cyanine dye compound (10) and 5.8 g of sodium (p) -alkylbenzenesulfonate are mixed with 305 ml of distilled water, and the mixture is used with a sand mill (1/4 Gallon sand grinder mill, manufactured by IMEX Co., Ltd.). The beads were dispersed to obtain a dye solid fine particle dispersion having an average particle size of 0.2 μm.

(Preparation of antihalation layer coating solution)
1.Gelatin 17g
2.Polyacrylamide 9.6g
3.70g of solid fine particle dispersion of the above base precursor
4. 56g solid fine particle dispersion of the above dye
5. Polymethylmethacrylate fine particles (average particle size 6.5 μm) 1.5g
6.Polyethylene sulfonate 2.2g
7.Blue dye compound (11) below 0.2g

8. H ₂ O 844ml
(Preparation of back surface protective layer coating solution)
The container was kept at 40 ° C., and the following additives were added to form a protective layer coating solution.

1.Gelatin 50g
2.Polystyrene sulfonate 0.2g
3. N, N'-ethylenebis (vinylsulfonacetamide) 2.4g
4. Sodium t-octylphenoxyethoxyethanesulfonate 1g
5.C ₈ F ₁₇ SO ₃ K 32mg
6.C ₈ F ₁₇ SO ₂ N (C ₃ H ₇ ) (CH ₂ CH ₂ O) ₄ (CH ₂ ) ₄ -SO ₃ Na 64mg
7.Compound (12) 30mg

8.H ₂ O 950ml
(Creation of antihalation back layer)
On the back side of the polyethylene terephthalate film (support) provided with an undercoat layer having a thickness of 175 μm, apply an antihalation layer coating solution so that the solid content of the solid fine particle dye is 0.04 g / m ^2. Further, the back surface protective layer coating solution was simultaneously applied and dried so that the gelatin coating amount was 1 g / m ² , thereby preparing an antihalation back layer.

  A sample of the photothermographic material was prepared by simultaneously coating the surface opposite to the back layer surface from the undercoat surface in the order of the emulsion layer, the intermediate layer, the protective layer first layer, and the protective layer second layer by the slide bead coating method. .

  The coating was performed at a speed of 160 m / min, the distance between the coating die tip and the support was set to 0.18 mm, and the pressure in the decompression chamber was set to 392 Pa lower than the atmospheric pressure. In the subsequent chilling zone, air with a dry bulb temperature of 18 ° C and a wet bulb temperature of 12 ° C was blown for 30 seconds to cool the coating solution, and then in the drying zone, the dry bulb temperature was 30 ° C and the wet bulb temperature was The solvent in the coating solution was volatilized by blowing dry air at 18 ° C. for 200 seconds. The average wind speed of the wind sprayed on the coating liquid film surface in the chilling zone and the drying zone was 7 m / sec.

(Measurement of melting point)
The obtained dispersions (a) to (e) were dried at low temperature, the melting point was measured with a differential scanning calorimeter (type TA7000, manufactured by ULVAC), and the difference from the melting point of the base precursor compound alone was determined. It was shown to.

(Evaluation of thermal decolorization)
Each sample of the photothermographic material thus prepared was subjected to thermal development at 120 ° C. for 20 seconds in the plate heater type thermal development apparatus 10 shown in FIG. 1 of the embodiment of Japanese Patent Application No. 9-229684, and the emulsion surface After the film removal on the side, the residual color of the back layer was evaluated by the absorbance at 660 nm as a ratio (%) to the untreated absorbance. Table 1 shows the results as thermal decoloring properties. 5% or less is preferable.

(water resistant)
Similarly, each sample of the photothermographic material thus prepared was subjected to heat development at 120 ° C. for 20 seconds in a dark place with a plate heater type heat developing machine to produce an unexposed development product, and one drop of water on the back surface. After hanging down and leaving for 30 seconds, the sample was lightly wiped and naturally dried, and then the sample was observed with white light passing through a milky white plate and visually evaluated.

I can't see any traces of water ...
I can see some traces of water droplets but I don't care ...
The water drop traces are clearly visible and the image is disturbed.
Evaluation was performed in the above three stages, and the results are shown in Table 1.

  The samples of the present invention clearly have the effect of promoting decolorization and improving water resistance. When the samples 2 to 5 were exposed to a photothermographic material with a 635 nm semiconductor laser sensitometer, the photosensitive material was similarly processed at 120 ° C. for 20 seconds (thermal development). It was.

Example 2
In Example 1, the spectral sensitizing dye A used was replaced with the spectral sensitizing dye B in equimolar amounts, and the base precursor solid fine particle dispersion and the dye solid fine particle dispersion were changed as follows. A photothermographic material sample was prepared.

(Preparation of solid fine particle dispersion (f), (g) of base precursor)
64 g of base precursor compound (7), 10 g of diphenylsulfone compound (8), 10 g of 4-chloro (phenyl) sulfone compound (9), and 10 g of surfactant Demol N Kao Co., Ltd. were mixed with 220 ml of distilled water. Bead dispersion using a sand mill (1/4 Gallon sand grinder mill, manufactured by IMEX Co., Ltd.) to obtain a solid fine particle co-dispersion liquid (f) of a base precursor compound and a diphenyl sulfone compound having an average particle diameter of 0.2 μm. Moreover, the same co-dispersion liquid (g) was obtained using 14 g of diphenylsulfone compound (8) and 14 g of compound (13) [mp147 ° C.].

(Preparation of solid fine particle dispersion (h), (i) of base precursor)
64 g of the base precursor compound (7), 12 g of the 4-chlorophenyl (phenyl) sulfone compound (9), 12 g of the compound (13) and 10 g of surfactant Demol N10 manufactured by Kao Corporation were mixed with 220 ml of distilled water, and the mixture was mixed with a sand mill ( Disperse beads using a 1/4 Gallon sand grinder mill (made by Imex Co., Ltd.), and obtain a solid fine particle dispersion (h) of base precursor compound and 4-chlorophenyl (phenyl) sulfone compound with an average particle size of 0.2 μm. The same co-dispersion liquid (i) was obtained using 18 g of 4-chlorophenyl (phenyl) sulfone compound (9) and 18 g of compound (13).

(Preparation of solid fine particle dispersion (j) of base precursor)
64 g of the base precursor compound (7), 6.4 g of the compound (14) [mp129 ° C.], 6.4 g of the compound (15) [mp113 ° C.] and 10 g of the surfactant Demol N made by Kao Corporation were mixed with 220 ml of distilled water. The mixed solution was dispersed in beads using a sand mill (1/4 Gallon sand grinder mill, manufactured by Imex Co., Ltd.), and an average particle size of 0.2 μm, a solid of a base precursor compound, compound (14) and compound (15) A fine particle co-dispersion liquid (j) was obtained.

(Preparation of dye solid fine particle dispersion)
9.6 g of the following cyanine dye compound (16) and 5.8 g of sodium (p) -alkylbenzenesulfonate are mixed with 305 ml of distilled water, and the mixture is used with a sand mill (1/4 Gallon Sand Grinder Mill, manufactured by IMEX Co., Ltd.). The beads were dispersed to obtain a dye solid fine particle dispersion having an average particle size of 0.2 μm.

  These samples were evaluated in the same manner as in Example 1 and are shown in Table 2.

  The samples of the present invention clearly have the effect of promoting decolorization and improving water resistance. The samples 6 to 10 were exposed to a photothermographic material with a 635 nm semiconductor laser sensitometer, and then the photosensitive material was similarly processed at 120 ° C. for 20 seconds (thermal development), and had excellent photographic performance. .

  The samples 6 to 10 were exposed to a photothermographic material using a 663 nm semiconductor laser (35 mW2) sensitometer, and then thermally developed in the same manner. -When duplicated with a film MI-Dup for ray photo reproduction, an excellent reproduction was obtained.

  Example 3 Sample 11 was prepared in the same manner as in Sample 3 of Example 1, except that the cyanine dye compound (17) was replaced in an equimolar amount instead of the cyanine dye compound (10). When evaluated in the same manner, the thermal decoloring property was 0% and the water resistance was “◯”. Further, when Samples 3 and 11 were stored in the dark at 50 ° C. and 75% RH for 5 days, the optical density of each cyanine dye was not decreased for Sample 3, but the optical density was decreased for Sample 11. It was seen.

FIG. 2 is a schematic cross-sectional view of a plate heater type heat development apparatus. FIG. 2 is a schematic cross-sectional view of a plate heater type thermal development apparatus having a drive roller.

Explanation of symbols

18 Heat Developing Unit 120 Plate Heater 122 Pressing Roller 125 Insulation Cover 126 Supply Roller Pair 128 Discharge Roller Pair 130 Drive Roller

Claims (7)

A photothermographic material having at least one photosensitive layer on a support, comprising a non-photosensitive layer containing a compound represented by the following formula (I):

[In Formula (I), R ⁰¹ and R ⁰² each independently represents an aliphatic group, an aromatic group or a heterocyclic group. However, the compound represented by the formula (I) does not have a carboxyl group or a carboxyl group salt as a substituent. ]   The photothermographic material according to claim 1, comprising silver halide, an organic silver salt, a reducing agent and a binder.   Having at least one non-photosensitive layer containing a base-bleachable dye or a salt thereof, wherein at least one of the non-photosensitive layer and its adjacent non-photosensitive layer is a base precursor and the above formula (I) The photothermographic material according to claim 1 or 2, which comprises a compound represented by:   4. The photothermographic material according to claim 3, wherein the base precursor and the compound represented by the formula (I) are co-dispersed and contained.   The photothermographic material according to claim 1, wherein the non-photosensitive layer and its adjacent non-photosensitive layer are on a surface opposite to the photosensitive layer with respect to a support. 6. The photothermographic material according to claim 1, wherein the dye capable of being bleached by the base or a salt thereof is a cyanine dye represented by the following formula (II).

[In the formula (II), R ¹ represents an electron-withdrawing group, R ² represents a hydrogen atom, an aliphatic group or an aromatic group, and R ³ and R ⁴ each independently represents a hydrogen atom, a halogen atom or an aliphatic group. Group, aromatic group, —NR ⁶ R ⁷ , —OR ⁶ or —SR ⁷ , R ⁶ and R ⁷ each independently represent a hydrogen atom, an aliphatic group or an aromatic group, and R ⁵ represents an aliphatic group L ¹ , L ² and L ³ are each independently an optionally substituted methine, and the methine substituent is bonded to form an unsaturated aliphatic ring or an unsaturated heterocyclic ring. May be. Z ¹ and Z ² are each independently an atomic group forming a 5- or 6-membered nitrogen-containing heterocycle, and the nitrogen-containing heterocycle may be condensed with an aromatic ring, and the nitrogen-containing heterocycle And the condensed ring thereof may have a substituent. m represents 0, 1, 2, or 3. ]   7. The photothermographic material according to claim 1, wherein the base precursor is a diacid base precursor.

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