JP2005122013A - Heat developable photosensitive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat developable photosensitive material superior in preservation and improving the humidity dependance of processing. <P>SOLUTION: The heat development photosensitive material, having an image forming layer, contains organic silver particles, halide silver particles and a reducing agent on a support. The heat developable sensitive material has an acrylic hydrophobic resin layer containing at least one kind selected from among microcrystalline wax and paraffin wax at the side of the image forming layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photothermographic material.

  Silver halide photosensitive materials that have been widely used in the past are used in the field of image formation as a broader and higher quality material due to their excellent photographic properties, but development, fixing, The process of washing with water and drying is necessary, and the processing steps are wet, so that the work is complicated. For this reason, a photothermographic material in which the development process is performed by heat treatment has been developed and put into practical use, and in recent years, it has been rapidly spread mainly in the printing industry or the medical industry.

  As such a technique, a photothermographic material having an organic silver salt, photosensitive silver halide grains and a reducing agent on a support is known. Since this photothermographic material does not use any solution processing chemicals, a simpler system can be provided to the user.

  In particular, in the field of printing plate making, waste liquids resulting from wet processing of image-forming photosensitive materials have become operational problems. In recent years, reduction of processing waste liquids is strongly desired from the viewpoint of environmental protection and space saving.

  Photothermographic materials (also referred to as photosensitive materials) are extremely susceptible to humidity, and photographic performance varies significantly with humidity. Particularly in the low humidity period in winter, there is a problem that the amount of water in the photosensitive material is reduced during storage and the development reaction is difficult to proceed, and the density does not come out.

  As a conventional technique, a technique for subtracting vinylidene chloride to reduce the influence of humidity is known, but there is an environmental problem. In addition, techniques for increasing the thickness of the protective layer and changing the drying temperature are known but insufficient.

  In particular, photothermographic materials for photoengraving, especially scanners and image setters, contain reducing agents and organic contrast agents with a molecular weight of 500 or more that have a low dependency on the development humidity of the character line width and good image storage stability. A technology for providing a super high contrast photothermographic material (for example, see Patent Document 1), and a technology for providing a photothermographic material having improved environmental temperature and humidity dependency while using a highly active reducing agent (for example, Patent Literature 1). 2), a technology for providing a photothermographic material having high photographic properties, excellent storability when not developed, and exhibiting optimum photographic characteristics for photoengraving applications having low temperature and humidity dependence during character line width development. (See, for example, Patent Document 3.) Further, a photothermographic material having high sensitivity, low fog, high Dmax (maximum density), little increase in fog during storage, and low temperature-humidity dependency during development. Provided technology For example, refer to Patent Document 4.) Have been published. However, none of the techniques has improved the dependency on humidity.

Furthermore, the addition of an organic contrast agent causes deterioration of fog, sensitivity, storage stability, and the like, but a technique for satisfactorily obtaining a high contrast image without adding an organic contrast enhancer has not yet been established.
JP 2002-55409 A (pages 25-33) JP 2002-90935 A (pages 4-8) JP 2002-229153 A (pages 7 to 11) JP 2002-258436 A (7th to 17th pages)

  An object of the present invention is to provide a photothermographic material having excellent storage stability and improved processing humidity dependency.

The above object of the present invention can be achieved by the following configuration.
(Claim 1)
In a photothermographic material having an image forming layer containing organic silver particles, silver halide particles and a reducing agent on a support, the image forming layer side contains at least one selected from microcrystalline wax and paraffin wax. A photothermographic material having an acrylic hydrophobic resin layer.
(Claim 2)
A photothermographic material, wherein at least one silver ion reducing agent is a compound represented by the following general formula (1).

[In the formula, R ₁ , R ₂ , R ₃ and R ₄ each independently represents an alkyl group, but at least one group is a hydroxyl group or an alkyl having a substituent that can form a hydroxyl group by deprotection. Represents a group. L ₁ represents an —S— group or a —CR ₅ (R ₆ ) — group, and R ₅ and R ₆ are a hydrogen atom, an alkyl group, a 3- to 10-membered non-aromatic ring group, an aryl group, or a heteroaryl group. Represents. X ₁ and X ₂ represent groups that can be substituted on the benzene ring, and n and m each represents an integer of 0 to 2. ]
(Claim 3)
_{3. The} photothermographic sensor according to claim _2, wherein R ₂ and R _{3 in} the general formula (1) are a hydroxyl group or an alkyl group having a group capable of forming a hydroxyl group by deprotection as a substituent. material.
(Claim 4)
4. The photothermographic material according to claim 2, wherein the reducing agent represented by the general formula (1) is a reducing agent represented by the following general formula (2).

[Wherein, R ₁ , R ₄ , L ₁ , X ₁ , X ₂ , n and m are the same as those in the general formula (1). R ₅ and R ₆ represent a hydrogen atom or an alkyl group. p and q represent the integer of 0-5. ]
(Claim 5)
5. The photothermographic material according to claim 4, wherein R ₅ and R _{6 in} the general formula (2) are hydrogen atoms, and p and q are 2.
(Claim 6)
6. The photothermographic material according to claim _1, wherein R ₁ and R _{2 in the} general formulas (1) and (2) are secondary or tertiary alkyl groups.
(Claim 7)
L _{1 in the} general formulas (1) and (2) is a —CR ₅₅ (R ₆₆ ) — group, R ₅₅ is a 5- to 6-membered non-aromatic cyclic group, and R ₆₆ is a hydrogen atom. The photothermographic material according to claim 1, wherein the photothermographic material is provided.
(Claim 8)
The photothermographic material according to claim 1, further comprising a nucleating agent.

  According to the present invention, a photothermographic material having excellent storage stability and improved processing humidity dependency was obtained.

  The present invention will be described in more detail. As the acrylic hydrophobic resin preferably used in the present invention, for example, the acrylic ester monomer has 7 or more carbon atoms, and the alkyl group of the alcohol used to obtain the acrylic ester monomer has 3 or more carbon atoms. Examples thereof include an acrylic ester polymer, and a copolymer of the acrylic ester and styrene.

  Examples of the microcrystalline wax and paraffin wax preferably used in the present invention include EMUSTAR-0001 and EMUSTAR-0135 manufactured by Nippon Seiwa Co., Ltd.

  In the present invention, a specific compound in which at least one silver ion reducing agent is a bisphenol derivative is used alone or in combination with other reducing agents having different chemical structures. In the photothermographic material according to the present invention, it is possible to unexpectedly suppress performance deterioration due to fogging during storage, color tone deterioration during storage of a silver image after heat development, and the like.

  The reducing agent used in the present invention is preferably a bisphenol derivative represented by the general formulas (1) and (2).

First, the compound represented by the general formula (1) according to the present invention will be described in detail. In the general formula (1), R ₁ , R ₂ , R ₃ and R ₄ each independently represents an alkyl group. Examples thereof include an alkyl group having 1 to 15 carbon atoms (for example, methyl group, ethyl group, propyl group). Group, isopropyl group, tert-butyl group, pentyl group, hexyl group, decyl group, dodecyl group, pentadecyl group, etc.), halogenated alkyl group (for example, trifluoromethyl group, perfluorooctyl group, etc.), cycloalkyl group ( For example, a cyclopentyl group, a cyclohexyl group, a 1-methylcyclohexyl group, etc.), an alkynyl group (for example, a propargyl group), etc. can be mentioned. These groups may be further substituted, and examples of the substituent include alkyl groups (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, etc.) , Halogenated alkyl groups (eg, trifluoromethyl group, perfluorooctyl group, etc.), cycloalkyl groups (eg, cyclohexyl group, cyclopentyl group, etc.), alkynyl groups (eg, propargyl group), glycidyl groups, acrylate groups, methacrylates Group, aryl group (for example, phenyl group), heterocyclic group (for example, pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group, furyl group, pyrrolyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, selenazolyl group, sriphoranyl group, Piperidinyl group, pyrazolyl group, tetrazoli group Group), halogen atom (for example, chlorine atom, bromine atom, iodine atom, fluorine atom, etc.), alkoxy group (for example, methoxy group, ethoxy group, propyloxy group, pentyloxy group, cyclopentyloxy group, hexyloxy group, Cyclohexyloxy group etc.), aryloxy group (eg phenoxy group), alkoxycarbonyl group (eg methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group etc.), aryloxycarbonyl group (eg phenyloxycarbonyl group) ), Sulfonamide groups (for example, methanesulfonamide groups, ethanesulfonamide groups, butanesulfonamide groups, hexanesulfonamide groups, cyclohexanesulfonamide groups, benzenesulfonamide groups, etc.), sulfamoyl groups (for example, Minosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, phenylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), urethane group (for example, methylureido group) , Ethylureido group, pentylureido group, cyclohexylureido group, phenylureido group, 2-pyridylureido group, etc.), acyl group (for example, acetyl group, propionyl group, butanoyl group, hexanoyl group, cyclohexanoyl group, benzoyl group, Pyridinoyl group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclo Hexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), amide group (eg, acetamido group, propionamide group, butanamide group, hexaneamide group, benzamide group etc.), sulfonyl group (eg, methylsulfonyl group) , Ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, phenylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, anilino) Group, 2-pyridylamino group and the like), cyano group, nitro group, sulfo group, carboxyl group, hydroxyl group, oxamoyl group and the like.

At least one of R _{1 to} R ₄ is a hydroxyl group or an alkyl group having a substituent that can be deprotected to form a hydroxyl group, and is preferably an alkyl group having a hydroxyl group. The group that can be deprotected to form a hydroxyl group is preferably a group that forms a hydroxyl group by deprotection by the action of an acid and / or heat. Specifically, ether groups (methoxy groups, tert-butoxy groups, allyloxy groups, benzyloxy groups, triphenylmethoxy groups, trimethylsilyloxy groups, etc.), hemiacetal groups (tetrahydropyranyloxy groups, etc.), ester groups (acetyl) Oxy group, benzoyloxy group, p-nitrobenzoyloxy group, formyloxy group, trifluoroacetyloxy group, pivaloyloxy group, etc.), carbonate group (ethoxycarbonyloxy group, phenoxycarbonyloxy group, tert-butyloxycarbonyloxy group, etc.) ), Sulfonate groups (p-toluenesulfonyloxy group, benzenesulfonyloxy group etc.), carbamoyloxy groups (phenylcarbamoyloxy group etc.), thiocarbonyloxy groups (benzylthiocarbonyloxy group etc.), Ester group, sulfenates group (2,4-dinitrobenzene sulfenyl group and the like).

R ₁ and R ₄ are preferably an alkyl group having 1 to 4 carbon atoms, more preferably a secondary or tertiary alkyl group, and particularly preferably a tertiary alkyl group. Specifically, a tertiary alkyl group is preferably a tert-butyl group or a 1-methylcyclohexyl group. R ₂ and R ₃ are preferably an alkyl group having 1 to 4 carbon atoms, more preferably a hydroxyl group or an alkyl group substituted with a group capable of forming a hydroxyl group by deprotection. Most preferred is a hydroxymethyl group or a 2-hydroxyethyl group.

L ₁ represents an —S— group or a —CHR ₅ (R ₆ ) — group, preferably a —CHR ₅ (R ₆ ) — group. R ₅ and R _{6 each} represents a hydrogen atom, an alkyl group, a 3- to 10-membered non-aromatic ring group, an aryl group, or a heteroaryl group. Specific examples of the alkyl group include a methyl group, an ethyl group, and a propyl group. Butyl group, heptyl group, undecyl group, isopropyl group, 1-ethylpentyl group, 2,4,4-trimethylpentyl group and the like. Specific examples of 3 to 10-membered non-aromatic ring groups include cyclopropyl, aziridyl, oxiranyl as 3-membered rings, cyclobutyl, cyclobutenyl, oxetanyl, azetidinyl as 4-membered rings, and cyclopentyl, cyclopentenyl, cyclohexane as 5-membered rings Pentadienyl, tetrahydrofuranyl, pyrrolidinyl, tetrahydrothienyl, 6-membered ring is cyclohexyl, cyclohexenyl, cyclohexadienyl, tetrahydropyranyl, pyranyl, piperidinyl, dioxanyl, tetrahydrothiopyranyl, norcaranyl, norpinanyl, norbornyl, 7-membered ring As cycloheptyl, cycloheptynyl, cycloheptadienyl, 8-membered ring as cyclooctanyl, cyclooctenyl, cyclooctadienyl, cyclooctatrienyl, 9-membered ring Te is cyclononanyl, cyclononenyl, shea chrono Nagy enyl, cyclononatrienyl enyl, as the 10-membered ring cyclooctyl, Shikurodekeniru, cycloalkyl decadienyl include the group such as cyclopropyl tetradecatrienyl.

Preferably it is a 3-6 membered ring, More preferably, it is a 5-6 membered ring, Most preferably, it is a 6 membered ring, Among these, the hydrocarbon ring which does not contain a hetero atom is preferable. The ring may form a spiro bond with another ring through a spiro atom, or may be condensed in any way with another ring including an aromatic ring. Specific examples of the aryl group include a phenyl group, a naphthyl group, and an anthranyl group. Specific examples of heteroaryl groups include imidazole, pyrazole, pyridine, pyrimidine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiadiazole, oxadiazole, and quinoline. Group, phthalazine group, naphthyridine group, quinoxaline group, quinazoline group, cinnoline group, pteridine group, acridine group, phenanthroline group, phenazine group, tetrazole group, thiazole group, oxazole group, benzimidazole group, benzoxazole group, benzthiazole group, Indolenine group and tetrazaindene group can be mentioned. These groups can further have an optional substituent. Specifically as this substituent, it is synonymous with the substituent of the group represented by R < ₁ > -R < ₄ >.

R ₅ is preferably a hydrogen atom, an isopropyl group, a 2,4,4-trimethylpentyl group, or a 5- to 6-membered non-aromatic ring group (a cyclohexyl group, a cyclohexenyl group, or the like). R ₆ is preferably a hydrogen atom.

X ₁ and X ₂ each represents a group capable of substituting on the benzene ring, specifically, an alkyl group having 1 to 25 carbon atoms (methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, (Hexyl group, cyclohexyl group, etc.), halogenated alkyl group (trifluoromethyl group, perfluorooctyl group, etc.), cycloalkyl group (cyclohexyl group, cyclopentyl group, etc.), alkynyl group (propargyl group, etc.), glycidyl group, acrylate group , Methacrylate group, aryl group (phenyl group, etc.), heterocyclic group (pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group, furyl group, pyrrolyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, selenazolyl group, sriphoranyl group, piperidinyl group Group, pyrazolyl group, tetrazolyl group, etc.), halogen source Child (chlorine atom, bromine atom, iodine atom, fluorine atom, etc.), alkoxy group (methoxy group, ethoxy group, propyloxy group, pentyloxy group, cyclopentyloxy group, hexyloxy group, cyclohexyloxy group, etc.), aryloxy group (Phenoxy group etc.), alkoxycarbonyl group (methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group etc.), aryloxycarbonyl group (phenyloxycarbonyl group etc.), sulfonamide group (methanesulfonamide group, ethanesulfone) Amide group, butanesulfonamide group, hexanesulfonamide group, cyclohexanesulfonamide group, benzenesulfonamide group, etc.), sulfamoyl group (aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group) Butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, phenylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc., urethane group (methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, phenylureido group) 2-pyridylureido group), acyl group (acetyl group, propionyl group, butanoyl group, hexanoyl group, cyclohexanoyl group, benzoyl group, pyridinoyl group, etc.), carbamoyl group (aminocarbonyl group, methylaminocarbonyl group, dimethyl group) Aminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), Group (acetamide group, propionamide group, butanamide group, hexaneamide group, benzamide group, etc.), sulfonyl group (methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, phenylsulfonyl group, 2-pyridylsulfonyl group) Etc.), amino group (amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, anilino group, 2-pyridylamino group, etc.), cyano group, nitro group, sulfo group, carboxyl group, hydroxyl group, An oxamoyl group can be exemplified. These groups may be further substituted with these groups. n and m represent integers of 0 to 2, most preferably n and m are both 0.

Next, in the general formula (2), R ₅ and R ₆ each represent a hydrogen atom or an alkyl group. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a tert-butyl group, a pentyl group, A hexyl group etc. are mentioned. Preferably, both R ₅ and R ₆ are hydrogen atoms. p and q represent an integer of 0 to 5, preferably an integer of 1 to 3, and most preferably p = q = 2.

  Next, although the specific example of a compound represented by General formula (1) or (2) is enumerated, this invention is not limited to these.

  The compounds represented by the general formulas (1) and (2) of the present invention can be easily synthesized by a conventionally known method. A preferred synthetic scheme is illustrated below by taking Compound Example R-15 as an example.

  That is, preferably 2 equivalents of phenol and 1 equivalent of aldehyde are dissolved or suspended in the absence of a solvent or in a suitable organic solvent, and a catalytic amount of acid or alkali is added, preferably at a temperature of −20 ° C. to 180 ° C. The target R-15 can be obtained in good yield by reacting for 0.5 to 60 hours. The same applies to other exemplary compounds.

  The organic solvent is preferably a hydrocarbon organic solvent, and specific examples include benzene, toluene, xylene, dichloromethane, chloroform and the like. Preferred are toluene and xylene. Furthermore, it is most preferable to make it react without a solvent from the point of a yield. Although any inorganic acid and organic acid can be used as the acid catalyst, concentrated hydrochloric acid, p-toluenesulfonic acid, and phosphoric acid are preferably used. As the alkali catalyst, caustic soda, caustic potash, triethylamine, DBU, and sodium methylate are preferably used. The catalyst amount is preferably 0.001 to 1.5 equivalents relative to the corresponding aldehyde. The reaction temperature is preferably (15 ° C. to 150 ° C.), and the reaction time is preferably 3 to 20 hours.

  Although the reducing agent represented by General formula (1) or (2) may be used independently, you may use it in combination of 2 or more types. Moreover, you may use together the reducing agent of this invention, and other reducing agents.

  Examples of the reducing agent that can be used in combination with the reducing agent represented by the general formula (1) or (2) include paragraph numbers 0043 to 0045 of JP-A No. 11-65021, and page 7, page 34 of European Patent Publication No. EP0803764A1. Lines to 18th page, 12th line. In the photothermographic material of the invention, it is particularly preferable to use a bisphenol reducing agent (for example, 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane) in combination. The reducing agent represented by the general formulas (1) and (2) is preferably contained in an image forming layer containing an organic acid silver salt, but may be contained in an adjacent non-image forming layer.

  The reducing agent may be contained in the coating solution by any method such as a solution form, an emulsified dispersion form, a solid fine particle dispersion form, or the photosensitive material.

  In the present invention, further, U.S. Pat. Nos. 3,589,903, 4,021,249 or British Patent 1,486,148 and JP-A-51-51933, 50-36110, The polyphenol compounds described in JP-A-50-116023, JP-A-52-84727 or JP-B-51-35727, such as 2,2'-dihydroxy-1,1'-binaphthyl, 6,6'-dibromo-2 Bisnaphthols described in US Pat. No. 3,672,904 such as 2,2'-dihydroxy-1,1'-binaphthyl and the like, and further, for example, 4-benzenesulfonamidophenol, 2-benzenesulfonamidophenol US Patents such as 2,6-dichloro-4-benzenesulfonamidophenol, 4-benzenesulfonamidonaphthol Sulfonamidophenols or sulfonamidonaphthols, such as those described in 3,801,321 Pat also can be used as the silver ion reducing agent.

  The amount of the reducing agent used in the present invention varies depending on the type of organic silver salt, reducing agent, and other additives, but generally 0.05 mol to 10 mol, preferably 0.1 mol, per mol of organic silver salt. Molar to 3 molar is suitable. In the present invention, it may be preferable that the reducing agent is added to and mixed with a photosensitive emulsion solution composed of photosensitive silver halide and organic silver salt grains and a solvent immediately before coating, because photographic performance fluctuation due to stagnation time is small. is there.

  Next, the nucleating agent (also referred to as a high contrast agent) used in the present invention will be described.

  In the present invention, vinyl compounds represented by the following general formula (C1), general formula (C2) and general formula (C3) are preferably used as the nucleating agent.

In the general formula (C1), R ¹¹ , R ¹² and R ¹³ each independently represent a hydrogen atom or a substituent, Z represents an electron withdrawing group or a silyl group, R ¹¹ and Z, R ¹² and R ¹³ , R ¹³ and Z may be bonded to each other to form a cyclic structure.

In the general formula (C2), R ¹⁴ represents a substituent. In the general formula (C3), X and Y each independently represent a hydrogen atom or a substituent, and A and B each independently represent an alkoxy group, an alkylthio group, an alkylamino group, an arylthio group, an anilino group, a heterocyclic oxy group. Represents a group, a heterocyclic thio group or a heterocyclic amino group. In the general formula (C3), X and Y and A and B may be bonded to each other to form a cyclic structure.

  Specific examples of the general formula (C1), general formula (C2), and general formula (C3) include the following compounds.

  The organic silver salt according to the present invention is a reducible silver source and is an organic acid containing a reducible silver ion source. Examples of the organic acid used in the present invention include aliphatic carboxylic acid, carbocyclic carboxylic acid, heterocyclic carboxylic acid, heterocyclic compound and the like, but particularly long chain (10-30, preferably 15-25). The aliphatic carboxylic acid having the number of carbon atoms) and the heterocyclic carboxylic acid having a nitrogen-containing heterocyclic ring are preferably used. An organic silver salt complex having a total stability constant with respect to silver ions having a ligand of 4.0 to 10.0 is also useful.

  Examples of such organic acid silver salts are described in Research Disclosure (hereinafter abbreviated as RD) 17029 and 29963. Of these, silver salts of fatty acids are preferably used, and silver behenate, silver arachidate, and silver stearate are particularly preferably used.

  The organic silver salt compound described above can be obtained by mixing a water-soluble silver compound and a compound that forms a complex with silver, and a normal mixing method, a back mixing method, a simultaneous mixing method, and the like are preferably used. It is also possible to use a controlled double jet method as described in JP-A-9-127643.

  In the present invention, the organic silver salt preferably has an average particle size of 1 μm or less and is monodispersed. The average particle diameter of the organic silver salt is, for example, when the organic silver salt particles are spherical, rod-shaped, or tabular, the diameter when considering a sphere equivalent to the volume of the organic silver salt particles. Say. The average particle size is preferably 0.01 to 0.8 μm, particularly preferably 0.05 to 0.5 μm. Moreover, monodispersion is synonymous with the case of the below-mentioned silver halide, Preferably monodispersion degree is 1 to 30%. In the present invention, the organic silver salt is more preferably monodisperse particles having an average particle size of 1 μm or less, and an image having a high density can be obtained by setting the content within this range. Further, the organic silver salt preferably has tabular grains of 60% by number or more of the total organic silver. In the present invention, the tabular grains mean those having an average grain diameter / thickness ratio, that is, an aspect ratio (abbreviated as AR) represented by the following formula of 3 or more.

AR = average particle diameter (μm) / thickness (μm)
Such organic silver particles are preferably preliminarily dispersed together with a binder, a surfactant or the like, if necessary, and then dispersed and ground with a media disperser or a high-pressure homogenizer. As the disperser that can be used in the preliminary dispersion, for example, a general stirrer such as an anchor type or a propeller type, a high-speed rotating centrifugal radiation stirrer (dissolver), or a high-speed rotating shear stirrer (homomixer) may be used. it can. Examples of the media disperser include a rolling mill such as a ball mill, a planetary ball mill, and a vibration ball mill, a bead mill that is a medium agitation mill, an attritor, and other basket mills, and a high-pressure homogenizer. For example, various types such as a type that collides with a wall, a plug, etc., a type that allows liquids to collide with each other at high speed after dividing the liquid, and a type that allows a thin orifice to pass through can be used.

  In the apparatus used when dispersing the organic silver particles used in the present invention, for example, ceramics such as zirconia, alumina, silicon nitride, boron nitride, or diamond is used as the material of the member in contact with the organic silver particles. It is preferable to use zirconia, in particular.

  The organic silver particles used in the present invention preferably contain 0.01 to 0.5 mg of Zr per 1 g of silver, particularly preferably 0.01 to 0.3 mg of Zr. When carrying out the above dispersion, optimizing the binder concentration, the preliminary dispersion method, the dispersing machine operating conditions, the number of times of dispersion, etc. is very preferable as a method for obtaining the organic silver salt particles used in the present invention.

  The photosensitive silver halide according to the present invention preferably has a smaller average grain size, and preferably has an average grain size of 0.1 μm or less, more preferably, in order to suppress white turbidity after image formation and to obtain good image quality. 0.01-0.1 micrometer, especially 0.02-0.08 micrometer are preferable. The particle size here refers to the diameter (equivalent circle diameter) of a circle having the same area as each particle image observed with an electron microscope. The silver halide is preferably monodispersed. The monodispersion here means that the monodispersity obtained by the following formula is 40% or less. The particles are more preferably 30% or less, and particularly preferably 20% or less.

Monodispersity = (standard deviation of particle size) / (average particle size value) × 100
The shape of the photosensitive silver halide grains is not particularly limited, but the ratio occupied by the Miller index [100] plane is preferably high, and this ratio is 50% or more, further 70% or more, particularly 80% or more. Preferably there is. The ratio of the Miller index [100] plane is calculated by using the adsorption dependency between the [111] plane and the [100] plane in the adsorption of the sensitizing dye. Tani, J .; Imaging Sci. 29, 165 (1985).

  In the present invention, another preferred shape of the photosensitive silver halide is a tabular grain. The term “tabular grain” as used herein refers to those having an aspect ratio (r / h) of 3 or more when the square root of the projected area is the grain size r μm and the thickness in the vertical direction is h μm. Among them, the aspect ratio is preferably 3 to 50. Moreover, it is preferable that the particle size of a tabular grain is 0.1 micrometer or less, Furthermore, 0.01 micrometer-0.08 micrometer are preferable. These tabular grains are described in US Pat. Nos. 5,264,337, 5,314,798, 5,320,958, etc., and the desired tabular grains can be easily obtained. it can.

  The photosensitive halogen composition is not particularly limited, and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide, and silver iodide. The emulsion used in the present invention is P.I. Chifie et Physique Photographic (published by Paul Montel, 1967) by Glafkides. F. Duffin's Photographic Emission Chemistry (published by The Focal Press, 1966), V.C. L. It can be prepared based on the method described in Making and Coating Photographic Emulsion (published by The Focal Press, 1964) by Zelikman et al.

  The photosensitive silver halide according to the present invention preferably contains a metal ion belonging to Groups 6 to 11 of the periodic table. As the metal, W, Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, Pt, and Au are preferable.

  These metal ions can be introduced into the silver halide in the form of metal complexes or metal complex ions. As these metal complexes or metal complex ions, hexacoordinate metal complexes represented by the following general formula are preferable.

General formula [ML ₆ ] ^m
In the formula, M represents a transition metal selected from Group 6 to 10 elements of the periodic table, L represents a ligand, and m represents 0,-, 2-, 3-, or 4-. Specific examples of the ligand represented by L include halides (fluoride, chloride, bromide and iodide), cyanide, cyanate, thiocyanate, selenocyanate, tellurocyanate, azide and aco. A ligand, nitrosyl, thionitrosyl and the like can be mentioned, and ako, nitrosyl, thionitrosyl and the like are preferable. When an acoligand is present, it preferably occupies one or two of the ligands. L may be the same or different.

M is preferably rhodium (Rh), ruthenium (Ru), rhenium (Re), iridium (Ir) and osmium (Os). Specific examples of transition metal complex ions containing these include [RhCl ₆ ] ³⁻ [RuCl ₆ ] ³⁻ , [ReCl ₆ ] ³⁻ , [RuBr ₆ ] ³⁻ , [OsCl ₆ ] ³⁻ , [IrCl ₆ ] ⁴⁻ , [Ru (NO) Cl ₅ ] ²⁻ , [RuBr ₄ ] (H ₂ O)] ²⁻ , [Ru (NO) (H ₂ O) Cl ₄ ] ⁻ , [RhCl ₅ (H ₂ O)] ²⁻ , [Re (NO) Cl ₅ ] ²⁻ , [Re ( NO) (CN) ₅ ] ²⁻ , [Re (NO) Cl (CN) ₄ ], [Rh (NO) ₂ Cl ₄ ] ⁻ , [Rh (NO) (H ₂ O) Cl ₄ ] ⁻ , [Ru (NO) (CN) _5] ^2-, [Fe (CN) _6] ^3-, [Rh (NS) Cl _5] ^2-, [Os (NO) Cl _5] ^2-, [Cr NO) Cl _5] ^2-, [Re (NO) Cl _5] ^-, _{[Os (NS) Cl 4 (TeCN} ) ] ^2-, [Ru (NS) Cl _5] ^2-, [Re (NS) Cl ₄ (SeCN)] ²⁻ , [Os (NS) Cl (SCN) ₄ ] ²⁻ , [Ir (NO) Cl ₅ ] ²⁻ , [Ir (NS) Cl ₅ ] ^{2− and the} like.

One kind of metal ion, metal complex or metal complex ion described above may be used, or two or more kinds of the same kind of metal and different kinds of metals may be used in combination. The content of these metal ions, metal complexes or metal complex ions, generally is suitably 1 × 10 ^-9 ~1 × 10 ^-2 mol per mol of silver halide, preferably 1 × 10 ^{- 8} to 1 × 10 ⁻⁴ mol.

  These metal-providing compounds are preferably added at the time of silver halide grain formation and incorporated into the silver halide grains. Preparation of silver halide grains, that is, nucleation, growth, physical ripening, chemical sensitization It may be added at any stage before or after, but is preferably added at the stage of nucleation, growth and physical ripening, more preferably at the stage of nucleation and growth, most preferably Add at the stage of formation.

  In addition, it may be divided and added several times, or it can be uniformly contained in the silver halide grains. JP-A-63-29603, JP-A-2-306236, 3 As described in No. 167545, No. 4-76534, No. 6-110146, No. 5-273683, etc., it can also be contained with distribution in the particles. Preferably, a distribution can be provided inside the particles. These metal compounds can be added by dissolving in water or an appropriate organic solvent (for example, alcohols, ethers, glycols, ketones, esters, amides). A method of adding an aqueous solution or a metal compound and an aqueous solution in which NaCl and KCl are dissolved together to a water-soluble silver salt solution or a water-soluble halide solution during particle formation, or a silver salt solution and a halide solution are simultaneously mixed. When adding a third aqueous solution, a method of preparing silver halide grains by a three-liquid simultaneous mixing method, a method of adding an aqueous solution of a required amount of a metal compound to the reaction vessel during grain formation, or silver halide There is a method of adding another silver halide grain previously doped with a metal ion or complex ion at the time of preparation and dissolving it. In particular, a method of adding an aqueous solution of a metal compound powder or an aqueous solution in which a metal compound and NaCl, KCl are dissolved together is added to the water-soluble halide solution.

  When added to the particle surface, a required amount of an aqueous solution of a metal compound can be charged into the reaction vessel immediately after the formation of the particles, during physical ripening, or at the end or chemical ripening.

  In the present invention, the photosensitive silver halide grains may or may not be desalted after grain formation. However, when desalting is performed, for example, the noodle method, the flocculation method, etc. are known in the art. Can be washed with water and desalted.

  The silver halide grains used in the present invention are preferably chemically sensitized. As a preferable chemical sensitization method, a sulfur sensitization method, a selenium sensitization method, a tellurium sensitization method and the like well known in the art can be used. Further, noble metal sensitization methods such as gold compounds, platinum, palladium, iridium compounds, and reduction sensitization methods can be used.

  As the compound preferably used in the above-described sulfur sensitization method, selenium sensitization method, and tellurium sensitization method, known compounds can be used. For example, compounds described in JP-A-7-128768 are used. be able to. Examples of tellurium sensitizers include diacyl tellurides, bis (oxycarbonyl) tellurides, bis (carbamoyl) tellurides, diacyl tellurides, bis (oxycarbonyl) ditellurides, bis (carbamoyl) ditellurides, P = Compound having Te bond, tellurocarboxylates, Te-organyl tellurocarboxylates, di (poly) tellurides, tellurides, tellurols, telluroacetals, tellurosulfonates, compounds having P-Te bond Te-containing heterocycles, tellurocarbonyl compounds, inorganic tellurium compounds, colloidal tellurium, and the like can be used.

  Examples of the compound preferably used for the noble metal sensitization include, for example, chloroauric acid, potassium chloroaurate, potassium aurithiocyanate, gold sulfide, gold selenide, U.S. Pat. No. 2,448,060 and British Patent 618,061. The compounds described in No. etc. can be preferably used.

  As compounds used in the reduction sensitization method, for example, in addition to ascorbic acid and thiourea dioxide, for example, stannous chloride, aminoiminomethanesulfinic acid, hydrazine derivatives, borane compounds, silane compounds, polyamine compounds, etc. are used. Can do. Further, reduction sensitization can be performed by ripening the silver halide emulsion while maintaining the pH at 7 or higher or the pAg at 8.3 or lower. Further, reduction sensitization can be performed by introducing a single addition portion of silver ions during grain formation.

  Next, components of the photothermographic material of the present invention excluding the above-described items will be described.

  The photothermographic material of the present invention comprises an image forming layer containing the above-mentioned organic silver salt, photosensitive silver halide, and the reducing agent of the present invention and an acrylic hydrophobic resin layer laminated in this order on a support. Further, it is preferable that an intermediate layer or a protective layer is provided as necessary.

  Further, a photothermographic material in which a backing layer is provided on the surface opposite to the image forming layer to ensure transportability and prevent blocking with the protective layer can be suitably used. Each layer may be a single layer, or may be composed of two or more layers having the same or different composition.

  In the present invention, a binder resin is preferably used to form each of the above layers. As such a binder resin, a conventionally used transparent or translucent binder resin can be selected and used as appropriate. Examples of such a binder resin include polyvinyl formal, polyvinyl acetoacetal, and polyvinyl butyral. Polyvinyl acetal resins such as ethyl cellulose, hydroxyethyl cellulose, cellulose resins such as cellulose acetate butyrate, styrene resins such as polystyrene, styrene-acrylonitrile copolymers, styrene-acrylonitrile-acrylic rubber copolymers, polyvinyl chloride, chlorine Vinyl chloride-based resins such as modified polypropylene, polyester, polyurethane, polycarbonate, polyarylate, epoxy resin, acrylic resin, and the like. These may be used alone or in combination of two or more. It may be used in combination with fat.

  In addition, the said binder resin can be suitably selected and used for each layer of a protective layer, an intermediate | middle layer, or the backcoat layer provided when needed, unless the objective of this invention is impaired. In addition, you may use an epoxy resin, an acrylic monomer, etc. which can be hardened | cured with an active energy ray as a layer formation binder resin for an intermediate | middle layer and a backcoat layer. In the present invention, the following aqueous binder resins are also preferably used.

  Furthermore, a water-soluble polymer or a water-dispersible hydrophobic polymer (latex) can be used. For example, polyvinylidene chloride, vinylidene chloride-acrylic acid copolymer, vinylidene chloride-itaconic acid copolymer, sodium polyacrylate, polyethylene oxide, acrylic acid amide-acrylic acid ester copolymer, styrene-maleic anhydride copolymer Examples thereof include acrylonitrile-butadiene copolymer, vinyl chloride-acetic acid part nyl copolymer, and styrene-butadiene-acrylic acid copolymer. These constitute an aqueous coating solution, but form a uniform resin film at the stage of drying after coating and forming a coating film. When these are used, an organic silver salt, silver halide, reducing agent, etc. as an aqueous dispersion, mixed with these latexes to form a uniform dispersion, and then applied to form a heat-developable image forming layer Can be formed. By drying, the latex coalesces and forms a uniform film. Further, a polymer having a glass transition point of −20 ° C. to 80 ° C. is preferable, and −5 ° C. to 60 ° C. is particularly preferable. This is because if the glass transition point is high, the temperature at which heat development is carried out becomes high, and if it is low, fogging tends to occur, leading to a reduction in sensitivity and softening. The water-dispersed polymer is preferably dispersed in the form of fine particles having an average particle diameter in the range of 1 nm to several μm. The water-dispersed hydrophobic polymer is called a latex, and is preferably a latex that improves water resistance among widely used binders for aqueous coating. The amount of latex used for the purpose of obtaining water resistance as a binder is determined in consideration of applicability, but is preferably as large as possible from the viewpoint of moisture resistance. The ratio of latex to the total binder mass is preferably 50 to 100%, particularly preferably 80 to 100%.

In the present invention, as these binder resins, the amount of solids is 0.25 to 10 times the amount of silver attached, for example, when the amount of silver attached is 2.0 g / m ² , the amount of polymer attached is It is preferable that it is 0.5-20 g / m < ² >. Further, more preferably 0.5 to 7 times the grain-weight, for example, the amount with silver, if 2.0 g / m ^2, a 1.0~14g / m ^2. If the amount of binder resin is less than 0.25 times the amount of silver, the silver color tone may be significantly deteriorated and may not endure use, and if the amount is more than 10 times the amount of silver, it may become soft and endure use. is there.

  Further, the image forming layer according to the present invention includes, in addition to the above-described essential components and binder resin, an antifoggant, a toning agent, a sensitizing dye, and a substance that exhibits supersensitization (supersensitization). Various additives may also be added.

In the present invention, examples of the antifogging agent include compounds disclosed in US Pat. Nos. 3,874,946 and 4,756,999, —C (X ₁ ) (X ₂ ) ( X ₃ ) (wherein X ₁ and X ₂ represent a halogen atom, and X ₃ represents hydrogen or a halogen atom), a heterocyclic compound having one or more substituents, JP-A-9-288328, No. 9-90550, US Pat. No. 5,028,523 and European Patent Nos. 600,587, 605,981, 631,176, etc. be able to.

  Examples of toning agents added for the purpose of improving the silver tone after development include imides (for example, phthalimide); cyclic imides, pyrazolin-5-ones, and quinazolinones (for example, succinimide, 3-phenyl- 2-pyrazolin-5-one, 1-phenylurazole, quinazoline and 2,4-thiazolidinedione); naphthalimides (eg N-hydroxy-1,8-naphthalimide); cobalt complexes (eg cobalt hexamine trifluoro) Acetate), mercaptans (eg, 3-mercapto-1,2,4-triazole); N- (aminomethyl) aryl dicarboximides (eg, N- (dimethylaminomethyl) phthalimide); blocked pyrazoles , Isothiuronium ) Derivatives and certain photobleaching agents (eg, N, N′-hexamethylene (1-carbamoyl-3,5-dimethylpyrazole), 1,8- (3,6-dioxaoctane) bis (isothione) A combination of uronium trifluoroacetate) and 2- (tribromomethylsulfonyl) benzothiazole); a merocyanine dye (for example, 3-ethyl-5-((3-ethyl-2-benzothiazolinylidene (benzothiazolidine) Nylidene))-1-methylethylidene) -2-thio-2,4-oxazolidinedione); phthalazinone, phthalazinone derivatives or metal salts of these derivatives (eg 4- (1-naphthyl) phthalazinone, 6-chlorophthala Dinone, 5,7-dimethyloxyphthalazinone, and 2,3-dihydro-1,4-phthalazinedio ); A combination of phthalazinone and a sulfinic acid derivative (eg, 6-chlorophthalazinone + sodium benzenesulfinate or 8-methylphthalazinone + sodium p-trisulfonate); a combination of phthalazine + phthalic acid; a phthalazine (phthalazine adduct) And maleic anhydride, and phthalic acid, 2,3-naphthalenedicarboxylic acid or o-phenylene acid derivatives and anhydrides thereof (eg, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic acid) A combination with at least one compound selected from anhydride); quinazolinediones, benzoxazines, naltoxazine derivatives; benzoxazine-2,4-diones (eg, 1,3-benzoxazine-2,4-dione) Pyrimidines and asymmetric-tria Gins (eg, 2,4-dihydroxypyrimidine) and tetraazapentalene derivatives (eg, 3,6-dimercapto-1,4-diphenyl-1H, 4H-2,3a, 5,6a-tetraazapentalene) And preferred color toning agents are phthalazone and phthalazine. In addition, as long as it is a range which does not inhibit the objective of this invention, you may add a toning agent to the protective layer mentioned later.

  Further, examples of supersensitizers include RD 17643, JP-B Nos. 9-25500, 43-4933, JP-A-59-19032, 59-192242, JP-A-5-341432, and the like. In the present invention, a heteroaromatic mercapto compound represented by the following general formula (M), which is a general formula (Ma) that substantially forms the mercapto compound, can be used. The disulfide compounds represented can be used.

General formula (M)
Ar-SM
General formula (Ma)
Ar-SS-Ar
In the general formula (M), M represents a hydrogen atom or an alkali metal atom, and Ar represents a heteroaromatic ring or condensed heteroaromatic ring having one or more nitrogen, sulfur, oxygen, selenium or tellurium atoms. The heteroaromatic ring is preferably benzimidazole, naphthimidazole, benzothiazole, naphthothiazole, benzoxazole, naphthoxazole, benzoselenazole, benzotelrazole, imidazole, oxazole, pyrazole, triazole, triazine, pyrimidine, pyridazine, pyrazine, Pyridine, purine, quinoline or quinazoline. Moreover, in general formula (Ma), Ar is synonymous with the said general formula (M).

  The heteroaromatic ring includes, for example, a halogen atom (for example, Cl, Br, I), a hydroxy group, an amino group, a carboxyl group, and an alkyl group (for example, one or more carbon atoms, preferably 1 to 4 carbon atoms). And a substituent selected from the group consisting of an alkoxy group (for example, one having 1 or more carbon atoms, preferably 1 to 4 carbon atoms).

  The supersensitizer used in the present invention is preferably used in the range of 0.001 to 1.0 mol per mol of silver in the emulsion layer containing the organic silver salt and silver halide grains, and particularly 1 mol of silver. The range is preferably 0.01 to 0.5 mol per unit.

  The image recording layer according to the present invention may contain a macrocyclic compound containing a hetero atom. A 9-membered or larger macrocyclic compound containing at least one of a nitrogen atom, an oxygen atom, a sulfur atom and a selenium atom as a heteroatom is preferred, a 12-24 membered ring is more preferred, and a 15-21 membered ring is still more preferred. is there.

  A typical compound is crown ether, which was synthesized by Pederson in 1967 and has been synthesized many times since its unique report. These compounds are C.I. J. et al. Pederson, Journal of American chemical society vol, 86 (2495), 7017-7036 (1967), G.P. W. Gokel, S.M. H, Korzenowski, “Macrocyclic polyethr synthesis”, Springer-Vergal (1982) and the like.

  In addition to the additives described above, for example, surfactants, antioxidants, stabilizers, plasticizers, ultraviolet absorbers, coating aids and the like may be used for the image forming layer according to the present invention. As these additives and the other additives described above, compounds described in RD Item 17029 (June 1978, p. 9-15) are preferably used.

  In the present invention, the image forming layer may be a single layer or a plurality of layers having the same or different compositions. The film thickness of the image forming layer is usually 10 to 30 μm.

  Examples of the support used in the photothermographic material of the invention include acrylic ester, methacrylic ester, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyarylate, polyvinyl chloride, polyethylene, polypropylene, polystyrene. , Nylon, aromatic polyamide, polyetheretherketone, polysulfone, polyethersulfone, polyimide, polyetherimide, triacetylcellulose, and other resin films, as well as resin films obtained by laminating two or more layers of the above resins. be able to.

  In the image recording method described later, the support according to the present invention is developed with heat after forming a latent image to form an image. Therefore, a support that has been stretched into a film and heat-set is preferable in terms of dimensional stability. In addition, you may add fillers, such as a titanium oxide, a zinc oxide, barium sulfate, a calcium carbonate, in the range which does not inhibit the effect of this invention. In addition, the thickness of a support body is about 10-500 micrometers, Preferably it is 25-250 micrometers.

  As the protective layer used in the photothermographic material of the present invention, the binder resin described in the above image forming layer can be selected and used as necessary.

  As an additive to be added to the protective layer, it is preferable to contain a filler for the purpose of ensuring damage prevention and transportability of the image after heat development, and the content when the filler is added is in the layer forming composition. It is preferable to contain 0.05-30 mass%.

  Furthermore, in order to improve slipperiness and chargeability, the protective layer may contain a lubricant and an antistatic agent. Examples of such lubricants include fatty acids, fatty acid esters, fatty acid amides, and polyoxyethylene. , Polyoxypropylene, (modified) silicone oil, (modified) silicone resin, fluororesin, carbon fluoride, wax and the like, and antistatic agents include cationic surfactants, anionic surfactants Agents, nonionic surfactants, polymer antistatic agents, metal oxides or conductive polymers, etc., "11290 Chemical Products", Chemical Industry Daily, p. 875-876 etc., the compound described in US Patent No. 5,244,773 columns 14-20, etc. can be mentioned. Furthermore, various additives added to the image forming layer may be added to the protective layer as long as the object of the present invention is not hindered. About 20 mass% is preferable, More preferably, it is 0.05-10 mass%.

  In the present invention, the protective layer may be a single layer or may be composed of a plurality of layers having the same or different composition. In addition, the film thickness of a protective layer is 1.0-5.0 micrometers normally.

  In the present invention, in addition to the above-mentioned image forming layer, support and protective layer, an intermediate layer for improving film attachment between the support and the image forming layer is provided, and a back coat layer is provided for the purpose of transportability and antistatic. In the case of installation, the thickness of the intermediate layer is usually 0.05 to 2.0 μm, and the thickness of the backing layer is usually 0.1 to 10 μm.

  The coating solution for the image forming layer, the coating solution for the protective layer, and the coating solution for the intermediate layer and the backing layer that are installed according to the present invention respectively dissolve or disperse the above-described components in a solvent. Can be prepared.

  Solvents that can be used in the above preparation may be those having a solubility parameter value in the range of 6.0 to 15.0 shown in “Solvent Pocket Book” edited by the Society of Synthetic Organic Chemistry. Examples of the solvent that can be used in the coating solution for forming each layer according to the invention include ketones such as acetone, isophorone, ethyl amyl ketone, methyl ethyl ketone, and methyl isobutyl ketone. Examples of alcohols include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, diacetone alcohol, cyclohexanol, and benzyl alcohol. Examples of glycols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, hexylene glycol and the like. Examples of ether alcohols include ethylene glycol monomethyl ether and diethylene glycol monoethyl ether. Examples of ethers include ethyl ether, dioxane, isopropyl ether and the like. Examples of the esters include ethyl acetate, butyl acetate, amyl acetate, isopropyl acetate and the like. Examples of hydrocarbons include n-pentane, n-hexane, n-heptane, cyclohexane, benzene, toluene, xylene and the like. Examples of the chlorides include methyl chloride, methylene chloride, chloroform, dichlorobenzene and the like, but are not limited to these as long as the effects of the present invention are not impaired.

These solvents can be used alone or in combination of several kinds. The residual amount of the solvent in the photothermographic material can be adjusted by appropriately setting the temperature conditions of the drying step after coating, and the residual solvent amount is preferably 5 to 1000 mg / m ^{2 in} total. preferably, a 10-300 mg / m ^2.

  When dispersion is necessary when preparing the coating liquid, for example, a two-roll mill, a three-roll mill, a ball mill, a pebble mill, a cobol mill, a tron mill, a sand mill, a sand grinder, a Sqgvari attritor, a high-speed impeller disperser, a high-speed stone Conventionally known dispersers such as a mill, a high-speed impact mill, a disper, a high-speed mixer, a homogenizer, an ultrasonic disperser, an open kneader, and a continuous kneader can be selected and used as appropriate.

  To apply the coating solution prepared as described above, for example, extrusion-type extrusion coater, reverse roll coater, gravure roll coater, air doctor coater, blade coater, air knife coater, squeeze coater, impregnation coater, bar coater, Various known coater stations such as transfer roll coaters, kiss coaters, cast coaters, spray coaters and the like can be selected and used as appropriate. Among these coaters, it is preferable to use a roll coater such as an extrusion type extrusion coater or a reverse roll coater in order to eliminate unevenness in the thickness of the formation layer.

  Further, when the protective layer is applied, there is no particular limitation as long as the image forming layer is not damaged, but the solvent used in the protective layer forming coating solution may dissolve the image forming layer. In the above-described coater station, an extrusion-type extrusion coater, a gravure roll coater, a bar coater or the like can be used. Of these, when using a coating method such as a gravure roll coater or bar coater, the rotation direction of the gravure roll or bar may be forward or reverse with respect to the transport direction. A constant speed or a peripheral speed difference may be provided.

  Furthermore, when laminating each constituent layer, coating and drying may be repeated for each layer, but simultaneous multilayer coating may be performed by a wet-on-wet method and dried. In that case, for example, reverse roll coater, gravure roll coater, air doctor coater, blade coater, air knife coater, squeeze coater, impregnation coater, bar coater, transfer roll coater, kiss coater, cast coater, spray coater, etc. and extrusion type extrusion coater. In such a wet-on-wet multi-layer coating, the upper layer is applied while the lower layer is in a wet state. improves.

  Furthermore, in the present invention, it is preferable that the temperature at which the coating film is dried is in the range of 65 to 100 ° C. in order to effectively draw out the object of the present invention after at least applying the coating solution for the image forming layer. When the drying temperature is lower than 65 ° C., the reaction is insufficient, and thus the sensitivity may vary with time. When the drying temperature is higher than 100 ° C., the photothermographic material itself immediately after production may be changed. Since fogging (coloring) may occur, it is not preferable. The drying time cannot be generally defined by the air volume at the time of drying, but it is usually preferable to dry in the range of 2 to 30 minutes.

  The above-mentioned drying temperature may be dried immediately after coating at a drying temperature in the above-mentioned temperature range, or the vicinity of the surface caused by the marangony of the coating liquid generated during drying or the drying air of warm air is initially dried. For the purpose of preventing unevenness (scratch skin) caused by this, the initial drying temperature may be lower than 65 ° C., and then drying may be performed at a drying temperature in the above-described temperature range.

  As described above, the object of the present invention can be achieved by the photothermographic material of the present invention and the preferred production method thereof, but further, a clear image without interference fringes can be obtained by optimizing the image recording method. be able to.

  Next, an image recording method suitable for the photothermographic material of the present invention will be described in detail. In the present invention, as a preferred aspect of the image recording method, an image is formed by scanning exposure using a laser beam in which the angle formed by the exposure surface of the photothermographic material and the laser beam is not substantially perpendicular. Can be mentioned. In this way, by shifting the incident angle from the vertical, even if reflected light at the interlayer interface is generated, the optical path difference reaching the image forming layer becomes large, so that the scattering and attenuation of the laser light in the optical path is reduced. It occurs and interference fringes are less likely to occur. Here, “substantially not perpendicular” means that the angle that is closest to the vertical during laser scanning is preferably 55 ° to 88 °, more preferably 60 ° to 86 °, and still more preferably. It means 65 degrees or more and 84 degrees or less.

  In a laser used in a laser imager or laser image setter, the beam spot diameter on the exposed surface of the photothermographic material when scanned with the photothermographic material is generally from 5 to 75 μm as the minor axis diameter. The shaft diameter is in the range of 5 to 100 μm, and the laser beam scanning speed can be set to an optimum value for each photothermographic material depending on the sensitivity and laser power at the laser oscillation wavelength inherent to the photothermographic material.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, the embodiment of this invention is not limited to this.

1. Preparation of undercoated PET support 1 Plasma treatment 1 is performed on both surfaces of a 125 μm thick PET film that has been biaxially stretched and heat-set under the following conditions, and then the undercoating liquid a-1 is dried on one surface. After coating to a film thickness of 0.8 μm, drying is performed to form an undercoat layer A-1, and on the opposite side, an undercoat coating solution b-1 subjected to the following antistatic treatment is applied to a dry film thickness of 0.8 μm. After being coated so as to become an undercoat layer B-1 as a conductive layer. Next, plasma treatment 2 was performed on the surface of each undercoat layer under the following conditions.

<< Plasma treatment conditions >>
Using a batch type atmospheric pressure plasma processing apparatus (EC-I-H-340, manufactured by EC Chemical Co., Ltd.), the high frequency output is 4.5 kW, the frequency is 5 kHz, the processing time is 5 seconds, and the gas conditions are argon, Plasma treatment 1 and plasma treatment 2 were performed at a volume ratio of nitrogen and hydrogen of 90%, 5%, and 5%, respectively.

<Undercoat coating liquid a-1>
Butyl acrylate (30% by mass)
t-Butyl acrylate (20% by mass)
Styrene (25% by mass)
2-Hydroxyethyl acrylate (25% by mass)
270 g of copolymer latex liquid (solid content 30%)
Hexamethylene-1,6-bis (ethylene urea) 0.8g
Polystyrene fine particles (average particle size 3 μm) 0.05 g
Colloidal silica (average particle size 90μm) 0.1g
Finish to 1 liter with water <Undercoat coating solution b-1>
Tin oxide (average particle size 36nm doped with 0.1% indium)
Amount to be 0.26 g / m ² Butyl acrylate (30% by mass)
Styrene (20% by mass)
Glycidyl acrylate (40% by mass)
270 g of copolymer latex liquid (solid content 30%)
Hexamethylene-1,6-bis (ethylene urea) 0.8g
Finish to 1 liter with water <Heat treatment of support>
In the undercoating drying step of the obtained undercoated support, the support was heated at 140 ° C. and then gradually cooled. In that case, it conveyed with the tension | tensile_strength of 1 * 10 < ⁵ > Pa.

2. Coating on the back layer side The back layer coating solution 1 and the back protective layer coating solution 1 having the following compositions were filtered using a filter having an absolute filtration accuracy of 20 μm before coating, respectively, and then charged on the prepared support by an extrusion coater. On the surface of the undercoat layer B-1 subjected to the prevention processing, simultaneous multilayer coating was performed at a speed of 120 m / min so that the total wet film thickness was 30 μm, and drying was performed at 60 ° C. for 4 minutes.

<Back layer coating solution 1>
Methyl ethyl ketone 16.4 g / m ²
Infrared dye-A 17 mg / m ²
Stabilizer B-1 (Sumitomo Chemical Company Sumitizer BPA) 20 mg / m ²
Stabilizer B-2 (Yoshitomi Pharmaceutical Tomissorb 77) 50 mg / m ²
Cellulose acetate propylate (Eastman Chemical CAP504-0.2) 0.5 g / m ²
Cellulose acetate butyrate (Eastman Chemical CAP482-20) 1.5 g / m ²

<Back protective layer coating solution 1>
Methyl ethyl ketone 22g / m ²
Antistatic agent; (CH ₃ ) ₃ SiO — [(CH ₃ ) ₂ SiO] ₂ O— [CH ₃ SiO {CH ₂ CH ₂ CH ₂ O (CH ₂ CH ₂ O) ₁₀ (CH ₂ CH ₂ CH ₂ O ) ₁₅ CH ₃ }] ₃ O—Si (CH ₃ ) ₃
22 mg / m ²
Fluorine-based surfactant F-1: C ₈ F ₁₇ SO ₃ Li 10 mg / m ²
Cellulose acetate propyleneate (Eastman Chemical CAP504-0.2) 0.5 g / m ²
Cellulose acetate butyrate (Eastman Chemical CAP482-20) 1.5 g / m ²
Matting agent (Fuji Devison Psyroid 74; silica having an average particle size of 7 μm) 12 mg / m ²
(Preparation of silver halide grains)
In 900 ml of pure water, 7.5 g of gelatin and 10 mg of potassium bromide were dissolved, adjusted to a temperature of 35 ° C. and a pH of 3.0, and then brominated at a molar ratio of (96/4) with 370 ml of an aqueous solution containing 74 g of silver nitrate. Potassium, potassium iodide, and an aqueous solution containing 5 × 10 ⁻⁶ mol / liter of (NH ₄ ) ₂ RhCl ₅ (H ₂ O) were added over 10 minutes by the controlled double jet method while maintaining pAg 7.7. . Thereafter, 0.3 g of 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene was added, the pH was adjusted to 5 with sodium hydroxide, the average particle size was 0.06 μm, and the projected diameter area Silver halide grains made of cubic silver iodobromide having a coefficient of variation of 8% and a {100} face ratio of 86% were obtained. This emulsion was coagulated and precipitated using a gelatin flocculant, desalted and then 0.1 g phenoxyethanol was added to adjust the pH to 5.9 and pAg 7.5.

(Preparation of organic fatty acid silver emulsion)
10.6 g of behenic acid was placed in 300 ml of water, dissolved by heating at 90 ° C., 31.1 ml of 1 M / L sodium hydroxide was added with sufficient stirring, and the mixture was left as it was for 1 hour. Thereafter, the mixture was cooled to 30 ° C., 7.0 ml of 1 M / L phosphoric acid was added, and 0.01 g of N-bromosuccinimide was added with sufficient stirring. Thereafter, silver halide grains prepared in advance were added with stirring in a state heated to 40 ° C. so that the amount of silver was 10 mol% with respect to behenic acid. Further, 25 ml of 1M silver nitrate aqueous solution was continuously added over 2 minutes, and the mixture was left for 1 hour with stirring.

  To this emulsion, polyvinyl butyral dissolved in ethyl acetate was added and stirred sufficiently, and then allowed to stand to separate into an ethyl acetate phase containing silver behenate grains and silver halide grains and an aqueous phase. After removing the aqueous phase, silver behenate particles and silver halide particles were collected by centrifugation. Thereafter, 20 g of synthetic zeolite A-3 (spherical) manufactured by Tosoh Corp. and 22 ml of isopropyl alcohol were added and left for 1 hour, followed by filtration. Further, 3.4 g of polyvinyl butyral and 23 ml of isopropyl alcohol were added, and the mixture was sufficiently stirred at 35 ° C. and dispersed at a high speed to complete the preparation of the organic fatty acid silver emulsion.

(Photosensitive layer coating solution composition)
Organic fatty acid silver emulsion 1.4g (in silver) / m ²
Pyridinium hydrobromide perbromide 1.5 × 10 ⁻⁴ mol / m ²
Calcium bromide 1.8 × 10 ⁻⁴ mol / m ²
2- (4-Chlorobenzoyl) benzoic acid 1.5 × 10 ⁻³ mol / m ²
Infrared sensitizing dye 4.2 × 10 ⁻⁶ mol / m ²
2-mercaptobenzimidazole 3.2 × 10 ⁻³ mol / m ²
2-Tribromomethylsulfonylquinoline 6.0 × 10 ⁻⁴ mol / m ²
4-methylphthalic acid 1.6 × 10 ⁻³ mol / m ²
Tetrachlorophthalic acid 7.9 × 10 ⁻⁴ mol / m ²
Reducing agent: listed in Table 1 4.8 × 10 ⁻³ mol / m ²
Infrared dye-A 3.0 × 10 ⁻⁵ mol / m ²
Comparative reducing agent: 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane

(Protective layer composition)
A protective layer coating solution was prepared as follows.

Cellulose acetate butyrate 4g / m ²
Phthalazine 3.2 × 10 ⁻³ mol / m ²
As the solvent, methyl ethyl ketone, acetone, and methanol were appropriately used.

(Acrylic hydrophobic resin layer coating solution)
Acrylic hydrophobic resin 2g / m ²
Microcrystalline wax 0.3g / m ²
Matting agent (particle size 2 μm) 50 mg / m ²
(Acrylic resin solid component: 40% by mass)
(Coating on the photosensitive layer side)
The photosensitive layer coating solution, the protective layer coating solution, and the acrylic hydrophobic resin layer coating solution are sequentially applied to the support coated with the back layer side to form the photosensitive layer, the surface protective layer, and the acrylic hydrophobic resin layer. After coating, heat-developable photographic light-sensitive materials 1 to 10 were produced.

Evaluation of photographic performance (exposure)
The obtained sample was used in a single channel cylindrical inner surface type laser exposure apparatus equipped with a semiconductor laser having a beam diameter (FWHM of ½ of the beam intensity) of 12.56 μm, a laser output of 50 mW, and an output wavelength of 783 nm, and the rotational speed of the mirror. Exposure was performed at 60000 rpm and an exposure time of 1.2 × 10 ⁻⁸ seconds. The overlap coefficient at this time was 0.449, and the laser energy density on the surface of the heat-developable image recording material was 75 μJ / cm ² .

(Heat development)
The heat development processing was performed at 120 ° C. for 17.2 seconds.

(Evaluation of photographic performance)
A photothermographic material was prepared at 23 ° C. and 80% humidity for 12 hours and at 23 ° C. and 20% humidity for 12 hours, and was subjected to heat development processing by exposure to a line width of 50 μm in the same environment. The development humidity dependency was evaluated by measuring the difference in line width after each treatment. In addition, Dmin (fogging) in each environment was also evaluated. The results are shown in Table 1.

  From Table 1, it can be seen that the sample of the present invention is excellent in development humidity dependency.

Example 2
The same procedure as in Example 1 was performed except that the nucleating agent was added as described below.

(Photosensitive layer coating solution composition)
Organic fatty acid silver emulsion 1.4g (in silver) / m ²
Pyridinium hydrobromide perbromide 1.5 × 10 ⁻⁴ mol / m ²
Calcium bromide 1.8 × 10 ⁻⁴ mol / m ²
2- (4-Chlorobenzoyl) benzoic acid 1.5 × 10 ⁻³ mol / m ²
Infrared sensitizing dye 4.2 × 10 ⁻⁶ mol / m ²
2-mercaptobenzimidazole 3.2 × 10 ⁻³ mol / m ²
2-Tribromomethylsulfonylquinoline 6.0 × 10 ⁻⁴ mol / m ²
4-methylphthalic acid 1.6 × 10 ⁻³ mol / m ²
Tetrachlorophthalic acid 7.9 × 10 ⁻⁴ mol / m ²
Reducing agent: listed in Table 2 4.8 × 10 ⁻³ mol / m ²
Infrared dye-A 3.0 × 10 ⁻⁵ mol / m ²
Nucleator: Species and amounts listed in Table 2 Comparative reducing agent: 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane (protective layer composition)
A protective layer coating solution was prepared as follows.

Cellulose acetate butyrate 4g / m ²
Phthalazine 3.2 × 10 ⁻³ mol / m ²
Nucleator: Species and amounts listed in Table 2 Methyl ethyl ketone, acetone, and methanol were appropriately used as the solvent.

(Acrylic hydrophobic resin layer coating solution)
Acrylic hydrophobic resin 2g / m ²
Microcrystalline wax 0.3g / m ²
Matting agent (particle size 2 μm) 50 mg / m ²
(Acrylic resin solid component: 40% by mass)
(Coating on the photosensitive layer side)
The photosensitive layer coating solution, the protective layer coating solution, and the acrylic hydrophobic resin layer coating solution are sequentially applied to the support coated with the back layer side to form the photosensitive layer, the surface protective layer, and the acrylic hydrophobic resin layer. After coating, heat-developable photographic light-sensitive materials 21 to 30 were produced.

(Raw preservation)
A part of the coated sample was subjected to a forced deterioration test at 55 ° C. for 3 days, and the other part was left at room temperature to evaluate the sensitivity and fog by the method of Example 1. The results are shown in Table 2.

  From Table 2, it can be seen that the sample of the present invention is stable against forced deterioration.

Claims (8)

In a photothermographic material having an image forming layer containing organic silver particles, silver halide particles and a reducing agent on a support, the image forming layer side contains at least one selected from microcrystalline wax and paraffin wax. A photothermographic material having an acrylic hydrophobic resin layer. A photothermographic material, wherein at least one silver ion reducing agent is a compound represented by the following general formula (1).

[In the formula, R ₁ , R ₂ , R ₃ and R ₄ each independently represents an alkyl group, but at least one group is a hydroxyl group or an alkyl having a substituent that can form a hydroxyl group by deprotection. Represents a group. L ₁ represents an —S— group or a —CR ₅ (R ₆ ) — group, and R ₅ and R ₆ are a hydrogen atom, an alkyl group, a 3- to 10-membered non-aromatic ring group, an aryl group, or a heteroaryl group. Represents. X ₁ and X ₂ represent groups that can be substituted on the benzene ring, and n and m each represents an integer of 0 to 2. ] _{3. The} photothermographic sensor according to claim _2, wherein R ₂ and R _{3 in} the general formula (1) are a hydroxyl group or an alkyl group having a group capable of forming a hydroxyl group by deprotection as a substituent. material. 4. The photothermographic material according to claim 2, wherein the reducing agent represented by the general formula (1) is a reducing agent represented by the following general formula (2).

[Wherein, R ₁ , R ₄ , L ₁ , X ₁ , X ₂ , n and m are the same as those in the general formula (1). R ₅ and R ₆ represent a hydrogen atom or an alkyl group. p and q represent the integer of 0-5. ] 5. The photothermographic material according to claim 4, wherein R ₅ and R _{6 in} the general formula (2) are hydrogen atoms, and p and q are 2. 6. The photothermographic material according to claim _1, wherein R ₁ and R _{2 in the} general formulas (1) and (2) are secondary or tertiary alkyl groups. L _{1 in the} general formulas (1) and (2) is a —CR ₅₅ (R ₆₆ ) — group, R ₅₅ is a 5- to 6-membered non-aromatic cyclic group, and R ₆₆ is a hydrogen atom. The photothermographic material according to claim 1, wherein the photothermographic material is provided. The photothermographic material according to claim 1, further comprising a nucleating agent.