JP2005084604A - Heat developable image recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat developable image recording material capable of image recording in a short wavelength band of ≤500 nm, excellent in long-term storage stability as a material for a scanner or an image setter, and enabling high definition and high contact printing. <P>SOLUTION: The heat developable image recording material has on a support an image forming layer containing at least a non-photosensitive organic silver salt, a reducing agent for the organic silver salt, a photosensitive silver halide, an ultra-contrast-enhancer and an organic binder and is imagewise exposed with light of ≤500 nm wavelength, wherein a chloride ion concentration of the layer containing the non-photosensitive organic silver salt is ≤1,000 ppm based on the amount of the non-photosensitive organic silver salt. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heat-developable image recording material for forming an image by heat development, and particularly relates to a heat-developable image recording material from which a high-contrast image suitable for printing plate making can be obtained.

  Examples of the heat-developable image recording material capable of forming an image using the heat-development processing method include US Pat. Nos. 3,152,904, 3,457,075, and “Imaging Processes and Materials”. ”, Nelson's 8th edition (1969), pages 279-291. The heat-developable image recording material disclosed herein includes a reducible silver source (for example, an organic silver salt), a catalytically active amount of a photocatalyst (for example, silver halide), a color toning agent that controls the color tone of silver, and a reducing agent. Is dispersed in the binder. The heat-developable image recording material is stable at normal temperature, but when heated to a high temperature (for example, 120 ° C.) after exposure, blackened silver is generated by an oxidation-reduction reaction between a reducible silver salt and a reducing agent. This reaction is promoted by the catalytic action of the latent image generated by exposure.

  Furthermore, in recent years, a super-high contrast agent that works effectively in such a heat-developable image recording material has been developed. As a result, a super-high contrast image recording material suitable for printing plate making has been developed. As the ultra-high contrast agent, acylhydrazines described in JP-A Nos. 10-10672, 10-31282, U.S. Pat. No. 5,496,695 and the like, U.S. Pat. No. 5,545,507. There are known acrylonitriles described in the specification and US Pat. No. 5,635,339.

  Such an image forming method does not require any processing liquid such as a developing solution, and an image can be obtained only by heating, and there is no generation of sulfurous acid gas or ammonia gas. Since it does not affect the environment, it is attracting attention as a new image forming method in the future. In recent years, image forming systems in which image information is digitized and stored, image-processed as necessary, transmitted via a network, and laser-output to a photosensitive material at a necessary place have spread. In such a working environment, the heat-developable image forming system is particularly preferable because there is no generation of gas or the like that corrodes and degrades electronic equipment.

  As a laser light source, coherent light such as argon, helium-neon, helium-cadmium is used. Recently, the spread of semiconductor lasers is remarkable. However, all of these laser tubes have shortcomings such as the necessity of using a dedicated driver for a high-voltage power supply, and the disadvantage that they cannot be increased in size. Further, as a disadvantage of the semiconductor laser, since the emission wavelength has been a long wavelength of 650 nm or more so far, the silver halide photographic light-sensitive material having photosensitivity in this region is inferior in storage stability. Easy to desensitize. The reason for this is the instability factor of the spectral sensitizing dye.

  At this point, a module in which an SHG (Second Harmonic Generator) element and a semiconductor laser are integrated and a blue semiconductor laser have been developed, and a laser output device in a short wavelength region has been closed up. The blue semiconductor laser is expected to increase in demand in the future because high-definition image recording is possible, the recording density is increased, and a stable output is obtained with a long lifetime. Accordingly, there is a need for a heat-developable laser light recording material that is compatible with blue lasers.

  There is a strong demand for heat-developable image recording materials to stably obtain high-definition images. For example, when stored for a long period of time under high temperature and high humidity, the sensitivity decreases and fog (minimum density). In other words, the halftone dot sharpness deteriorates due to problems such as an increase in tone and softening of gradation, and in particular, the characteristics of a blue semiconductor laser cannot be exhibited to the maximum.

  As a heat-developable laser light recording material corresponding to a blue laser, a heat-developable photosensitive material using photosensitive silver halide having a silver iodide content of 5 mol% or more and 100 mol% or less (see, for example, Patent Document 1), specific A photothermographic material containing a silver halide grain having an average grain size and a development accelerator (see, for example, Patent Document 2), and a dye having a specific structure was used for the image forming layer. A heat-developable image recording material (see, for example, Patent Document 3) is disclosed. However, in the above Patent Documents 1 to 3, regarding the dimensional change that occurs during the thermal development, in particular, regarding the above problem (storage stability) when applied to a photosensitive material for printing, the problem is pointed out and its improvement means. There is no teaching or suggestion.

On the other hand, in order to solve this, conventionally, a method has been proposed in which the halogen ion concentration on the surface side having the image forming layer is regulated within a specific range to improve the storage stability (see, for example, Patent Document 4). . However, in the above-mentioned patent document, there is no teaching or suggestion regarding the problem and the means for improving the storage stability in the heat-developable image recording material that is image-exposed with light having a wavelength of 500 nm or less. Absent.
JP 2003-91053 A JP 2003-162025 A JP 2003-167313 A JP 2003-66562 A

  An object of the present invention is to provide a heat-developable image recording material that can record an image in a short wavelength region of 500 nm or less, has excellent long-term storage stability for a scanner or an image setter, and enables high-definition and high-contrast printing. is there.

The above object of the present invention is achieved by the following configurations.
(Claim 1)
An image forming layer containing at least a non-photosensitive organic silver salt, a reducing agent for the organic silver salt, a photosensitive silver halide, a super-high contrast agent, and an organic binder is provided on the support, and an image is formed with light having a wavelength of 500 nm or less. In the heat-developable image recording material to be exposed, the chloride ion concentration in the non-photosensitive organic silver salt-containing layer is 1000 ppm or less with respect to the non-photosensitive organic silver salt.
(Claim 2)
The heat-developable image recording material according to claim 1, comprising a spectral sensitizing dye represented by the following general formula (1) or (2).

[Wherein, Z ¹ and Z ² are each independently unsubstituted or substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a phenyl group, or thiazoline. To form a ring, thiazole ring, benzothiazole ring, naphthothiazole ring, selenazole ring, benzoselenazole ring, naphthselenazole ring, oxazole ring, benzoxazole ring, naphthoxazole ring, imidazole ring, benzimidazole ring or pyridine ring Represents a necessary nonmetallic atom group, R ¹¹ and R ¹² each represent an alkyl group having 1 to 4 carbon atoms, a hydroxyalkyl group, a carboxyalkyl group or a sulfoalkyl group; n1 and n2 each represents 0 or 1; X ⁻ represents an anion, and m1 represents 1 or 2. ]

[In the formula, Z ³ is unsubstituted or substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a phenyl group, benzoxazole ring, thiazole ring, benzo Z ⁴ represents a nonmetallic atom group necessary for forming a thiazole ring, a selenazole ring, a benzoselenazole ring or a pyridine ring, and Z ⁴ represents a 2-thiohydratoin ring, a 2-thiooxazolidine-2,4′-dione ring or a rhodanine ring. Represents a group of nonmetallic atoms necessary for formation, R ¹⁴ represents an alkyl group having 1 to 4 carbon atoms, a carboxyalkyl group, or a hydrogen atom, R ¹⁵ represents an alkyl group having 1 to 4 carbon atoms or a hydrogen atom, n3 represents 0 or 1. ]

  According to the present invention, there is provided a heat-developable image recording material that can record an image in a short wavelength region of 500 nm or less, has excellent long-term storage stability for a scanner or an image setter, and enables high-definition and high-contrast printing. it can.

  Hereinafter, the best mode for carrying out the present invention will be described in detail, but the present invention is not limited thereto.

  As a result of intensive studies in view of the above problems, the inventor of the present invention is a heat-developable image recording material that is image-exposed with light having a wavelength of 500 nm or less, which is a problem of the present invention, and is long in a severe environment such as high temperature and high humidity. Important characteristic deterioration for scanners or imagesetters, such as reduced sensitivity, increased fog, or softening caused by storage for a long period of time, is caused by non-photosensitive chloride ion concentration in the layer containing the non-photosensitive organic silver salt. It has been found that it can be achieved by setting it to 1000 ppm or less with respect to the organic silver salt, and further has found that the effect can be further exhibited by using a sensitizing dye having a specific structure.

  Details of the present invention will be described below.

  The heat-developable image recording material of the present invention has an image forming layer containing photosensitive silver halide on a support, and more preferably a non-photosensitive protective layer on this layer.

  Image forming layer The image forming layer can be composed of one layer or a plurality of layers, and includes a non-photosensitive organic silver salt, a reducing agent for the silver salt, a photosensitive silver halide and an organic binder, It does not contain substantially. Further, examples of materials that can be preferably included include halogen precursors, phthalazine, and derivatives thereof. The image forming layer may be formed by laminating a plurality of layers, and these materials may be added to different layers and melted at the time of heat development so as to interact with each other. Alternatively, one material may be distributed and added to different layers.

  When the image forming layer is formed by a coating method, it is preferable to adjust the pH of the coating solution to 5.5 to 7.8 for the aqueous coating solution, and the acid used for the adjustment preferably does not contain a halogen. In the case of using a coating solution containing an organic solvent as a main solvent, it is important to adjust the viscosity, and it is preferable to adjust the viscosity to 1 mPa · s to 100 mPa · s to be lower than the protective layer. In either case of aqueous coating or organic solvent coating, it is preferable to apply a plurality of layers including a protective layer simultaneously.

  First, each component and layer configuration of the image forming layer will be described.

[Photosensitive silver halide]
In the present invention, silver chloride, silver chlorobromide, silver bromide, silver iodobromide, silver iodochlorobromide can be used as the photosensitive silver halide. Regarding the grain formation of the photosensitive silver halide emulsion, grains can be formed by the method described in paragraphs [0217] to [0224] of JP-A No. 11-119374, but the method is limited to this method. It is not something.

  Examples of the shape of the silver halide grains include cubes, octahedrons, tetradecahedrons, tabular shapes, spherical shapes, rod shapes, potato shapes, etc., but in the present invention, cubic grains or tabular grains are particularly preferred. preferable. The characteristics of the particle shape such as the aspect ratio and the surface index of the particle are the same as those described in paragraph [0225] of JP-A-11-119374.

  The grain size distribution of the silver halide grains used in the present invention preferably has a monodispersity value of 30% or less, more preferably 1 to 20%, and even more preferably 5 to 15%. Here, the monodispersity is defined as a percentage (%) (coefficient of variation) of a value obtained by dividing the standard deviation of the particle size by the average particle size. For convenience, the grain size of the silver halide grains is represented by a ridge length in the case of cubic grains, and the other grains (octahedral, tetradecahedral, tabular, etc.) are calculated by a projected area equivalent circle diameter.

  The preferred silver halide grains used in the present invention are high silver bromide emulsions having a halogen composition of 40 to 100 mol% bromine. The remaining 60 mol% is not particularly limited, and can be selected from silver chloride, silver bromide, and silver iodide. Silver iodide is particularly preferable. By using such a high silver bromide emulsion, a high-sensitivity heat-developable image recording material can be designed. From the viewpoint of sensitivity, the silver bromide content is more preferably 70 to 100 mol%, still more preferably 80 to 100 mol%, and particularly preferably 90 to 100 mol%.

  The distribution of the halogen composition in the grains may be uniform, the halogen composition may be changed stepwise, or may be continuously changed. Further, silver halide grains having a core / shell structure can be preferably used. A preferable structure is a 2- to 5-fold structure, more preferably 2- to 4-fold core / shell particles. A structure in which the core is high silver bromide or a structure in which the shell is high silver bromide can also be preferably used. A technique for localizing silver iodide on the grain surface can also be preferably used.

  The grain size of the silver halide emulsion used in the present invention is preferably 5 to 90 nm, more preferably 5 to 70 nm, still more preferably 5 to 55 nm, and particularly preferably 10 to 45 nm. preferable. The term “particle size” as used herein means an average diameter when converted into a circular image having the same area as the projected area observed with an electron microscope. The coating amount of such silver halide grains is 0.001 to 1.0 mol%, preferably 0.005 to 0.5 mol%, more preferably 0.01 to 0.1 mol% of silver mol of the organic acid silver described later. 0.2 mol%.

  Methods for forming photosensitive silver halide are well known in the art, such as those described in Research Disclosure No. 17029, June 1978, and US Pat. No. 3,700,458. Specifically, a method of preparing a photosensitive silver halide by adding a silver supply compound and a halogen supply compound to gelatin or another polymer solution, and then mixing with an organic silver salt Is used. In addition, the methods described in paragraphs [0217] to [0224] of JP-A-11-119374, JP-A-11-352627, and JP-A-2000-347335 are also preferred.

In the present invention, silver halide grains in which a hexacyano metal complex is present on the outermost surface of the grains are preferred. The hexacyano metal complexes include [Fe (CN) ₆ ] ⁴⁻ , [Fe (CN) ₆ ] ³⁻ , [Ru (CN) ₆ ] ⁴⁻ , [Os (CN) ₆ ] ⁴⁻ , [Co ( CN) ₆ ] ³⁻ , [Rh (CN) ₆ ] ³⁻ , [Ir (CN) ₆ ] ³⁻ , [Cr (CN) ₆ ] ³⁻ , [Re (CN) ₆ ] ^{3− and the} like. . In the present invention, a hexacyano Fe complex is preferred. The addition amount of the hexacyano metal complex is preferably 1 × 10 ⁻⁵ to 1 × 10 ⁻² mol, more preferably 1 × 10 ⁻⁴ to 1 × 10 ⁻³ mol, per mol of silver.

The photosensitive silver halide grains used in the present invention can contain a metal or metal complex of Group 8 to Group 10 of the Periodic Table (showing Groups 1 to 18). As the central metal of the group 8 to group 10 metal or metal complex of the periodic table, rhodium, ruthenium and iridium are preferable. One kind of these metal complexes may be used, or two or more kinds of complexes of the same metal and different metals may be used in combination. The preferable content is in the range of 1 × 10 ⁻⁹ to 1 × 10 ⁻³ mol with respect to 1 mol of silver. Regarding these heavy metals and metal complexes and methods for adding them, paragraph numbers [0018] to [0024] of JP-A-7-225449 and JP-A-11-65021, paragraphs of JP-A-11-119374. Nos. [0227] to [0240].

Furthermore, regarding a metal atom (for example, [Fe (CN) ₆ ] ⁴⁻ ) that can be contained in the silver halide grains used in the present invention, a desalting method and a sensitizing method for a silver halide emulsion, Paragraph numbers [0046] to [0050] of JP-A-11-84574, paragraph numbers [0025] to [0031] of JP-A-11-65021, paragraph number of JP-A-11-119374 0242] to [0250].

[Chemical sensitizer]
The photosensitive silver halide used in the present invention is preferably used after chemical sensitization. As a method of chemical sensitization, known methods such as sulfur sensitization method, selenium sensitization method, tellurium sensitization method and noble metal sensitization method can be used, and these are used alone or in combination. When used in combination, for example, sulfur sensitizing method and gold sensitizing method, sulfur sensitizing method and selenium sensitizing method and gold sensitizing method, sulfur sensitizing method and tellurium sensitizing method and gold sensitizing method, sulfur It is preferable to combine a sensitizing method, a selenium sensitizing method, a tellurium sensitizing method, a gold sensitizing method, and the like.

The amount of selenium sensitizer and tellurium sensitizer used in the selenium sensitization method and tellurium sensitization method can be appropriately selected according to the photosensitive silver halide grains, chemical ripening conditions, etc., but generally 1 mol of silver halide. Per 1 × 10 ⁻⁸ to 1 × 10 ⁻² mol, preferably about 1 × 10 ⁻⁷ to 1 × 10 ⁻³ mol can be used. Examples of the noble metal sensitizer used in the noble metal sensitization method include a gold sensitizer, a platinum sensitizer, a palladium sensitizer, an iridium sensitizer, and the like, and a gold sensitizer is particularly preferable. Specific examples of the gold sensitizer include chloroauric acid, potassium chloroaurate, potassium aurithiocyanate, gold sulfide and the like. In general, the gold sensitizer can be used in an amount of about 1 × 10 ⁻⁷ to 1 × 10 ⁻² mol per mol of silver halide.

  The photosensitive silver halide may be used after reduction sensitization. Specific examples of compounds used for reduction sensitization include ascorbic acid, thiourea dioxide, stannous chloride, aminoiminomethanesulfinic acid, hydrazine derivatives, borane compounds, silane compounds, and polyamine compounds. Further, reduction sensitization can be carried out by maintaining the pH of the photosensitive silver halide emulsion at 7 or higher, or by ripening while maintaining the pAg at 8.3 or lower. Furthermore, reduction sensitization can be performed by introducing a single addition portion of silver ions during grain formation. The photosensitive silver halide may coexist with a cadmium salt, a sulfite salt, a lead salt, a thallium salt or the like in the process of silver halide grain formation or physical ripening. Further, a thiosulfonic acid compound may be added by the method described in European Patent Publication No. 293,917A.

  In the present invention, only one type of photosensitive silver halide may be used, or two or more types (for example, those having different average grain sizes, those having different halogen compositions, those having different crystal habits, conditions for chemical sensitization) May be used in combination. The amount of the photosensitive silver halide used is preferably 0.1 to 100 mol%, more preferably 0.5 to 50 mol%, and particularly preferably 1.0 to 30 mol% with respect to the organic silver salt. Various gelatins can be used as the gelatin contained in the photosensitive silver halide emulsion used in the present invention. In order to satisfactorily maintain the dispersion state of the photosensitive silver halide emulsion in the organic silver salt-containing coating solution, it is preferable to use low molecular weight gelatin having a molecular weight of 500 to 60,000. These low molecular weight gelatins may be used at the time of particle formation or dispersion after the desalting treatment, but are preferably used at the time of dispersion after the desalting treatment.

[Reducing agent]
The reducing agent used in the present invention is a hindered phenol compound having at least one phenolic hydroxyl group and having an ortho position substituted with a substituent other than hydrogen. There may be one phenol ring or plural phenol rings in one molecule, but it is preferable to use a bis-type hindered phenol in which two hindered phenol groups are linked by a methylene group, a methine group, or a thio group. A compound. Specific examples of preferable reducing agents include general formulas (Ia), (Ib), (IIa), (IIb), (III) described in [0062] to [0074] of JP-A-9-274274. Compounds represented by (IVa) and (IVb).

  The reducing agent may be added to the image recording layer in any state such as a solution, a powder, a solid fine particle dispersion, an emulsion, and an oil protect dispersion. In the case of an aqueous coating solution, it is preferably added as fine particles dispersed in water with an average particle size of 0.01 μm to 10 μm. The solid fine particle dispersion can be performed by a known refinement means (for example, ball mill, vibration ball mill, sand mill, colloid mill, jet mill, roller mill, etc.). When dispersing the solid fine particles, a dispersion aid may be used. In the case of an organic solvent coating solution, the reducing agent is dissolved in an organic solvent and used. The addition amount of the reducing agent is 0.01 to 100 mol times, more preferably 0.1 to 10 mol times per mol of the organic silver salt in the image forming layer. The reducing agent may be added to the protective layer in addition to the image forming layer. The reducing agent may be a so-called precursor that is derivatized so as to function effectively only during development.

  In the present invention, it is preferable to use a non-reducing compound having a group capable of forming a hydrogen bond with an aromatic hydroxyl group (—OH) as a reducing agent. Examples of the group that forms a hydrogen bond with a hydroxyl group include a phosphoryl group, a sulfoxide group, a sulfonyl group, a carbonyl group, an amide group, an ester group, a urethane group, a ureido group, a tertiary amino group, and a nitrogen-containing aromatic group. Among them, preferred are a phosphoryl group, a sulfoxide group, an amide group (however, it has no> N—H group and is blocked like> N—Ra (Ra is a substituent other than H)), a urethane group. (However, it has no> N—H group and is blocked like> N—Ra (Ra is a substituent other than H)), a ureido group (however, it has no> N—H group,> N-Ra (Ra is a substituent other than H).)

  In the present invention, particularly preferred hydrogen bonding compounds are compounds represented by the following general formula (A).

In the general formula (A), R ^{21 to} R ²³ each independently represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, or a heterocyclic group, and these groups may be unsubstituted or substituted. You may have. When R ^{21 to} R ²³ have a substituent, examples of the substituent include a halogen atom, an alkyl group, an aryl group, an alkoxy group, an amino group, an acyl group, an acylamino group, an alkylthio group, an arylthio group, a sulfonamide group, and an acyloxy group. , An oxycarbonyl group, a carbamoyl group, a sulfamoyl group, a sulfonyl group, a phosphoryl group, and the like. Preferred as a substituent is an alkyl group or an aryl group, such as a methyl group, an ethyl group, an isopropyl group, a tert-butyl group, Examples thereof include a tert-octyl group, a phenyl group, a 4-alkoxyphenyl group, and a 4-acyloxyphenyl group.

Specific examples of the alkyl group for R ^{21 to} R ²³ include a methyl group, an ethyl group, a butyl group, an octyl group, a dodecyl group, an isopropyl group, a tert-butyl group, a tert-amyl group, a tert-octyl group, and a cyclohexyl group. Group, 1-methylcyclohexyl group, benzyl group, phenethyl group, 2-phenoxypropyl group and the like. Examples of the aryl group include a phenyl group, a cresyl group, a xylyl group, a naphthyl group, a 4-tert-butylphenyl group, a 4-tert-octylphenyl group, a 4-anisidyl group, and a 3,5-dichlorophenyl group. As the alkoxy group, methoxy group, ethoxy group, butoxy group, octyloxy group, 2-ethylhexyloxy group, 3,5,5-trimethylhexyloxy group, dodecyloxy group, cyclohexyloxy group, 4-methylcyclohexyloxy group, A benzyloxy group etc. are mentioned. Examples of the aryloxy group include a phenoxy group, a cresyloxy group, an isopropylphenoxy group, a 4-tert-butylphenoxy group, a naphthoxy group, and a biphenyloxy group. Examples of the amino group include a dimethylamino group, a diethylamino group, a dibutylamino group, a dioctylamino group, an N-methyl-N-hexylamino group, a dicyclohexylamino group, a diphenylamino group, and an N-methyl-N-phenylamino group. It is done.

R ^{21 to} R ²³ are preferably an alkyl group, an aryl group, an alkoxy group, or an aryloxy group. In terms of the effects of the present invention, at least one of R ^{21 to} R ²³ is preferably an alkyl group or an aryl group, and more preferably two or more are an alkyl group or an aryl group. Moreover, the case where R < ²¹ > -R < ²³ > is the same group from the point that it can obtain cheaply.

  Hereinafter, although the specific example of a hydrogen bondable compound including the compound represented by general formula (A) is illustrated, the hydrogen bondable compound which can be used by this invention is not limited to these.

  Specific examples of the hydrogen bonding compound include those described in JP-A No. 2001-281793, for example, in addition to the above.

  The compound represented by the general formula (A) can be used in the heat-developable image forming material after being contained in the coating solution in the form of a solution, an emulsified dispersion, or a solid dispersed fine particle dispersion, as with the reducing agent. The compound represented by the general formula (A) forms a hydrogen-bonding complex with a phenolic hydroxyl group in a solution state. Depending on the combination of the reducing agent and the compound represented by the general formula (A), Can be isolated in the crystalline state. The use of the crystal powder isolated in this way as a solid dispersion fine particle dispersion is particularly preferable for obtaining stable performance. Further, a method in which the reducing agent and the compound represented by the general formula (A) are mixed as powder and complexed at the time of dispersion with a sand grinder mill or the like using an appropriate dispersant can be preferably used.

  The compound represented by the general formula (A) is preferably used in the range of 1 to 200 mol%, more preferably in the range of 10 to 150 mol%, still more preferably 30 to 100 mol% with respect to the reducing agent. It is a range.

[Organic silver salt]
The organic silver salt used in the present invention is usually relatively stable to light, and is about 80 ° C. in the presence of development nuclei (latent images generated by exposure of photosensitive silver halide, etc.), reducing agents, etc. Alternatively, a silver image is formed when heated further. The organic silver salt is not particularly limited as long as it is an organic silver compound capable of supplying reducible silver ions, but is preferably a silver salt of an organic acid, more preferably a silver salt of an organic compound having a carboxyl group. Further, an organic or inorganic silver salt complex in which the ligand has a complex stability constant of 4.0 to 10.0 can also be preferably used.

  As a silver salt of an organic compound having a carboxyl group, a silver salt of an aliphatic carboxylic acid, a silver salt of an aromatic carboxylic acid, or the like can be used. The aliphatic carboxylic acid silver salt preferably has 10 to 30 carbon atoms, more preferably 15 to 28 carbon atoms. Preferred examples thereof include silver behenate, silver arachidate, silver stearate, silver oleate, and laurin. Examples thereof include silver oxide, silver caproate, silver myristate, silver palmitate, silver maleate, silver fumarate, silver tartrate, silver linoleate, silver butyrate and silver camphorate, and mixtures thereof.

  As the organic silver salt, a silver salt of a compound containing a mercapto group or a thione group and derivatives thereof can also be used. Preferred examples of such a silver salt include a silver salt of 3-mercapto-4-phenyl-1,2,4-triazole, a silver salt of 2-mercaptobenzimidazole, and a silver salt of 2-mercapto-5-aminothiadiazole. Silver salt of 2- (ethylglycolamido) benzothiazole, silver salt of thioglycolic acid such as silver salt of S-alkylthioglycolic acid (the alkyl group preferably has 12 to 22 carbon atoms), silver salt of dithioacetic acid, etc. Silver salt of dithiocarboxylic acid, silver salt of thioamide, silver salt of 5-carboxyl-1-methyl-2-phenyl-4-thiopyridine, silver salt of mercaptotriazine, silver salt of 2-mercaptobenzoxazole, US Pat. Silver salts described in US Pat. No. 4,123,274 (for example, silver salts of 3-amino-5-benzylthio-1,2,4-thiazole, etc. 2,4-mercaptothiazole derivative silver salt), a silver salt of 3- (3-carboxyethyl) -4-methyl-4-thiazoline-2-thione described in US Pat. No. 3,301,678. Examples thereof include silver salts of thione compounds.

  As the organic silver salt, a compound containing an imino group can also be used. Preferred examples thereof include silver salts of benzotriazole and derivatives thereof, silver salts of benzotriazole such as silver methylbenzotriazole, silver salts of halogen-substituted benzotriazole such as silver 5-chlorobenzotriazole, US Pat. No. 4,220. , 709, silver salt of 1,2,4-triazole or 1H-tetrazole, silver salt of imidazole and imidazole derivatives, and the like. Further, silver acetylide compounds described in US Pat. Nos. 4,761,361 and 4,775,613 can also be used.

  The shape of the organic silver salt is not particularly limited, and may be various shapes such as a needle shape, a scale shape, and a lump shape, but is preferably a needle shape or a scale shape. The shape of the organic silver salt can be determined from a transmission electron microscope image of the organic silver salt dispersion. In the case of acicular crystals, the minor axis is preferably 0.01 to 0.20 μm, the major axis is preferably 0.10 to 5.0 μm, the minor axis is 0.01 to 0.15 μm, and the major axis Is more preferably 0.10 to 4.0 μm. The particle size distribution of the organic silver salt is preferably monodispersed.

  The organic silver salt is preferably used after desalting. The method for performing the desalting is not particularly limited, and a known filtration method such as circular filtration, suction filtration, ultrafiltration, and floc-forming water washing by a coagulation method can be preferably used.

The amount of the organic silver salt used is preferably 0.1 to 5.0 g / m ² as the amount of silver with respect to the area of the image recording layer, and preferably 0.3 to 2.5 g / m ^2. More preferred.

(Super-high contrast agent)
The kind of the super-high contrast agent used in the present invention is not particularly limited. As a well-known super-high contrast agent, a hydrazine derivative represented by the formula (H) described in JP-A No. 2000-284399 (specifically Specifically, hydrazine derivatives described in Tables 1 to 4 of the same publication), JP-A-10-10672, JP-A-10-161270, JP-A-10-62898, JP-A-9-304870. Disclosed in JP-A-9-304872, JP-A-9-304871, JP-A-10-31282, US Pat. No. 5,496,695, European Patent Publication 741,320A. All hydrazine derivatives can be mentioned. Further, as the ultrahigh contrast agent that is particularly preferably used, there are substituted alkene derivatives, substituted isoxazole derivatives and specific acetal compounds represented by the general formulas (1) to (3) described in JP-A No. 2000-284399. Yes, more preferably, cyclic compounds represented by the general formula (A) or general formula (B) described in the publication, specifically, compounds 1 to 72 described in the chemical publications 8 to 12 of the publication are used. be able to. Further, a plurality of these ultrahigh contrast agents may be used in combination.

The ultrahigh contrast agent may be water or a suitable organic solvent such as alcohols (eg, methanol, ethanol, propanol, fluorinated alcohol), ketones (eg, acetone, methyl ethyl ketone). ), Dimethylformamide, dimethyl sulfoxide, methyl cellosolve and the like. In addition, by using a well-known emulsification dispersion method, it is dissolved using an oil such as dibutyl phthalate, tricresyl phosphate, glyceryl triacetate or diethyl phthalate, or an auxiliary solvent such as ethyl acetate or cyclohexanone. Then, an emulsified dispersion can be mechanically prepared and used. Alternatively, the powder of the ultrahigh contrast agent may be dispersed in a suitable solvent such as water by a ball mill, a colloid mill, or ultrasonic waves by a method known as a solid dispersion method. The ultrahigh contrast agent may be added to any layer on the image forming layer side with respect to the support, but is preferably added to the image forming layer or a layer adjacent thereto. The addition amount of the ultrahigh contrast agent is preferably 1 × 10 ^{−6 to 1} mol, more preferably 1 × 10 ^{−5 to} 5 × 10 ⁻¹ mol, and more preferably 2 × 10 ⁻⁵ to 2 × 10 ⁻¹ mol, relative to 1 mol of silver. Is most preferred.

  In addition to the above compounds, US Pat. Nos. 5,545,515, 5,635,339, 5,654,130, International Publication WO97 / 34196 pamphlet And compounds described in US Pat. No. 5,686,228, or JP-A-11-119372, JP-A-11-133546, JP-A-11-119373, and JP-A-11-109546. The compounds described in JP-A-11-95365, JP-A-11-95366, and JP-A-11-149136 may be used.

  In the present invention, in order to form a super high contrast image, a high contrast accelerator can be used in combination with the super high contrast agent. For example, amine compounds described in US Pat. No. 5,545,505, specifically AM-1 to AM-5, hydroxamic acids described in US Pat. No. 5,545,507, specific examples HA-1 to HA-11, acrylonitriles described in US Pat. No. 5,545,507, specifically CN-1 to CN-13, US Pat. No. 5,558,983 Hydrazine compounds, specifically CA-1 to CA-6, Onum salts described in JP-A-9-297368, specifically A-1 to A-42, B-1 to B -27, C-1 to C-14, and the like can be used.

[Organic binder]
The heat-developable image forming material of the present invention is characterized in that the chloride ion concentration in the non-photosensitive organic silver salt-containing layer is 1000 ppm or less with respect to the non-photosensitive organic silver salt. If it is too low, it is preferably 1 to 500 ppm, more preferably 10 to 300 ppm from the viewpoint of causing a decrease in sensitivity.

  In the present invention, there is no particular limitation on the means for adjusting the chloride ion concentration as defined above. However, a polymer latex is used as the organic binder, and the chloride ion which is a halogen ion in the polymer latex is defined in the present invention. It is preferable that it is contained in the viewpoint that the objective effect of the present invention can be exhibited without regret.

  Organic binders are usually composed of natural polymers, synthetic resin polymers, copolymers, other media forming films, such as hydrophobically modified gelatin, modified polyvinyl alcohol, cellulose acetate, cellulose acetate butyrate. , Polyvinylpyrrolidone, polyvinyl acetate, polyvinyl chloride, polyacrylates, polymethyl methacrylates, copoly (styrene-maleic anhydride), copoly (styrene-acrylonitrile), copoly (styrene-butadiene), polyvinyl acetals (e.g. , Polyvinyl formal, polyvinyl butyral, etc.), polyesters, polyurethanes, phenoxy resins, polyvinylidene chloride, polyepoxides, polycarbonates, polyvinyl acetate, polyamides, etc. And the like. The organic binder may be formed from a solution of water or an organic solvent, or an emulsion.

  The organic binder used in the present invention is preferably a hydrophobic and thermoplastic organic polymer. The term “thermoplasticity” as used herein is broader than the strict definition of thermoplasticity in the physicochemical term, and refers to the property of softening or melting when the polymer is heated above a certain temperature, depending on the properties of the polymer. means. This is similar to the fact that “plastic”, which means a thermoplastic resin, is practically used not only for linear polymers but also for three-dimensionally cross-linked rubber elastic polymers. Therefore, for example, an SBR polymer having rubber elasticity, depending on the degree of crosslinking, softens or melts when heated to the heat development temperature, and forms a state in which development and reaction can occur because the migration and diffusion of the substance is facilitated. Can be used as an organic binder.

  The organic binder is preferably a polymer latex, particularly preferably a polymer latex dispersed in water.

  In the present invention, it is preferable to contain halogen ions in this polymer latex. Examples of the halogen ion include fluorine ion, chlorine ion, bromine ion, and iodine ion, and from the viewpoint of photographic performance, preferable examples include chlorine ion, bromine ion, and iodine ion. Among these, chlorine ion is preferable. Bromine ions are preferred, and it is particularly preferred to use chloride ions to adjust the chloride ion concentration defined in the present invention.

  The halogen ion content contained in the polymer latex is preferably 500 ppm or less, more preferably 200 ppm or less, and particularly preferably 100 ppm or less with respect to the latex liquid. When the halogen ion content with respect to the latex exceeds 500 ppm, the image storability deteriorates. The halogen ion content is preferably 1200 ppm or less, more preferably 500 ppm or less, and particularly preferably 250 ppm or less with respect to the latex solid content. Hereinafter, when the halogen ion content is indicated, the halogen ion content relative to the latex liquid is indicated.

  Here, the measurement of the halogen ion content contained in the polymer latex was performed by using an ultrafiltration membrane such as Sartorius Centriart I (cut-off 5000), pretreating the measurement sample with a centrifuge (3000 rpm for 1 hour), and ion chromatography. Can be performed.

  Typical measurement conditions are shown below.

<Measurement condition>
Measuring apparatus: DIONEX DX500 type ion chromatography Separation column: AS-4a (F, Cl, Br) AS-12a (I)
Eluent: sodium carbonate / sodium hydrogen carbonate 4 mmol Flow rate: 1.2 ml / min
The polymer latex can also contain a chelate compound. As the chelate compound, a compound capable of coordinating (chelating) a multivalent ion such as a metal ion such as iron ion or an alkaline earth metal ion such as calcium ion is suitable. For example, JP-B-6-8956, US Pat. No. 5,053,322, JP-A-4-73645, JP-A-4-127145, JP-A-4-247703, JP-A-4-305572, JP-A-6-11805, JP-A-5-173712, JP-A-5-66527, JP-A-5-158195, JP-A-6-118580, JP-A-6-110168, JP-A-6-161054, JP-A-6-175299, JP-A-6-214352, JP-A-7-114161, JP-A-7-114154, JP-A-7-120894, JP-A-7-199433, JP-A-7-306504, JP-A-9-43792, JP-A-8-314090, JP-A-10-182571, JP-A-10-182570, JP-A-10-182570 The compounds described in 11-190892 can be used.

  As chelate compounds, inorganic chelate compounds (sodium tripolyphosphate, sodium hexametaphosphate, sodium tetrapolyphosphate, etc.), aminopolycarboxylic acid chelate compounds (nitrilotritriacetic acid, ethylenediaminetetraacetic acid, etc.), organic phosphonic acid chelate compounds (Research) Disclosure No. 18170, JP-A Nos. 52-102726, 53-42730, 56-97347, 54-121127, 55-4024, 55-4025, 55-29883, 55-126241, 55-65955, 55-65956, 57-17943, 54-61125, West German Patent 1,045,373, etc.), polyphenolic chelating agents , Polyami Preferably such systems chelate compounds, with aminopolycarboxylic acid derivatives being particularly preferred.

  Preferable examples of aminopolycarboxylic acid derivatives include the compounds in the attached table of EDTA (-Complexan Chemistry-) (Nanedo, 1977), and some of the carboxyl groups of these compounds are alkali metals such as sodium and potassium. A salt or ammonium salt may be substituted. Particularly preferred aminocarboxylic acid derivatives include iminodiacetic acid, N-methyliminodiacetic acid, N- (2-aminoethyl) iminodiacetic acid, N- (carbamoylmethyl) iminodiacetic acid, nitrilotriacetic acid, ethylenediamine-N, N '-Diacetic acid, ethylenediamine-N, N'-di-α-propionic acid, ethylenediamine-N, N'-di-β-propionic acid, N, N'-ethylene-bis (α-o-hydroxyphenyl) glycine N, N'-di (2-hydroxybenzyl) ethylenediamine-N, N'-diacetic acid, ethylenediamine-N, N'-diacetic acid-N, N'-diacethydroxamic acid, N-hydroxyethylethylenediamine-N , N ′, N′-triacetic acid, ethylenediamine-N, N, N ′, N′-tetraacetic acid, 1,2-propylenediamine-N, N, N ′ N'-tetraacetic acid, d, l-2,3-diaminobutane-N, N, N ', N'-tetraacetic acid, meso-2,3-diaminobutane-N, N, N', N'-four Acetic acid, 1-phenylethylenediamine-N, N, N ′, N′-tetraacetic acid, d, l-1,2-diphenylethylenediamine-N, N, N ′, N′-tetraacetic acid, 1,4-diaminobutane -N, N, N ', N'-tetraacetic acid, trans-cyclobutane-1,2-diamine-N, N, N', N'-tetraacetic acid, trans-cyclopentane-1,2-diamine-N, N, N ′, N′-tetraacetic acid, trans-cyclohexane-1,2-diamine-N, N, N ′, N′-tetraacetic acid, cis-cyclohexane-1,2-diamine-N, N, N ′ , N′-tetraacetic acid, cyclohexane-1,3-diamine-N, N, N ′, N′-four Acid, cyclohexane-1,4-diamine-N, N, N ', N'-tetraacetic acid, o-phenylenediamine-N, N, N', N'-tetraacetic acid, cis-1,4-diaminobutene- N, N, N ′, N′-tetraacetic acid, trans-1,4-diaminobutene-N, N, N ′, N′-tetraacetic acid, α, α′-diamino-o-xylene-N, N, N ', N'-tetraacetic acid, 2-hydroxy-1,3-propanediamine-N, N, N', N'-tetraacetic acid, 2,2'-oxy-bis (ethyliminodiacetic acid), 2,2 '-Ethylenedioxy-bis (ethyliminodiacetic acid), ethylenediamine-N, N'-diacetic acid-N, N'-di-α-propionic acid, ethylenediamine-N, N'-diacetic acid-N, N'- Di-β-propionic acid, ethylenediamine-N, N, N ′, N′-tetrapropionic acid Diethylenetriamine-N, N, N ′, N ″, N ″ -pentaacetic acid, triethylenetetramine-N, N, N ′, N ″, N ″ ′, N ″ ′-hexaacetic acid, 1,2,3-tri Aminopropane-N, N, N ′, N ″, N ″ ′, N ″ ′-hexaacetic acid, and some of the carboxyl groups of these compounds are substituted with alkali metal salts such as sodium and potassium, and ammonium salts. Also included are

  The chelate compound content contained in the polymer latex is 20 to 900 ppm with respect to the latex, more preferably 40 to 600 ppm, and particularly preferably 90 to 450 ppm. When the chelate compound concentration is less than 20 ppm, the capture of metal ions mixed in the production process of the polymer latex becomes insufficient, the stability against aggregation of the latex is lowered, and the coating property is deteriorated. On the other hand, if it exceeds 900 ppm, the viscosity of the latex increases to lower the coatability and further deteriorate the image storage stability. Moreover, although a chelate compound content is 50-2000 ppm with respect to latex solid content, it is more preferable that it is 100-1500 ppm, and it is especially preferable that it is 200-1000 ppm. Hereinafter, when the content of the chelate compound is shown, the content of the chelate compound with respect to the latex is shown.

  The polymer latex may contain a basic compound. The basic compound may be any of inorganic, organic or inorganic-organic mixed basic compounds. Examples of inorganic basic compounds include alkalis in the periodic table. Examples thereof include hydroxides of alkaline earth metals other than metal or beryllium, ammonia and the like, preferably lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, ammonia, Particularly preferred are lithium hydroxide, sodium hydroxide, potassium hydroxide and ammonia. Organic basic compounds include aliphatic amines (methylamine, ethylamine, diethylamine, triethylamine, etc.), aromatic amines (aniline, p-methoxyaniline, etc.), nitrogen-containing cyclic compounds (pyrrole, imidazole, pyridine, pyrazine). , Pyridazine, and derivatives thereof, preferably methylamine, ethylamine, triethylamine, and pyridine, and particularly preferably methylamine and triethylamine. These basic compounds may be used alone or in combination of two or more.

The basic compound contained in the polymer latex is used in an amount of 1.0 × 10 ⁻⁵ mmol or more, preferably 1.0 × 10 ⁻³ mmol or more, more preferably ^{5 based} on 1 g of the solid content of the polymer latex. 0.0 × 10 ⁻³ mmol or more and 1.0 mmol or less.

  The polymer latex preferably has a ratio (dv / dn) of volume average particle diameter (dv) to number average particle diameter (dn) of 1.0 to 1.10, more preferably dv / dn of 1. It is 0 to 1.05, more preferably 1.0 to 1.02. In principle, dv / dn does not become 1.0 or less, and if it exceeds 1.10, it may deviate greatly from the expected viscosity range from the average particle diameter, and a uniform surface state may not be obtained.

  Here, the number average particle diameter (dn) and the volume average particle diameter (dv) are values measured as follows, and the latex particle diameter is a direct observation method using a low-temperature transmission electron microscope. Can be analyzed.

  In order to directly observe the latex particle diameter using a transmission electron microscope, first, a latex dispersion diluted 20 times with water is placed on a mesh for observation with an electron microscope, immersed in liquid nitrogen and frozen, and then at a liquid nitrogen temperature. Perform electron microscope observation. The number average particle size and the volume average particle size are obtained by data processing of the photograph of the obtained particles with image processing software (for example, Win ROOF, manufactured by Mitani Corporation), and the particle size distribution is determined by the ratio. It was used as an index. The particle size distribution is preferably controlled by adjusting the addition amount of a surfactant described later. Specifically, the addition amount of the surfactant with respect to the monomer is preferably 0.05 to 10% by mass, and more preferably 0.1 to 5% by mass with respect to the total mass of the monomer.

  The polymer latex preferably has a number average particle size of 30 to 300 nm, more preferably 40 to 250 nm, and particularly preferably 50 to 200 nm. If the number average particle size is less than 30 nm, the thickening of the coating solution is remarkably increased, and uniform coating may not be possible. On the other hand, if the number average particle diameter exceeds 300 nm, the stability of the coating solution is poor, and aggregation and sedimentation may occur, making it impossible to obtain a homogeneous film.

  The polymer latex preferably has a solation rate of 5 to 55% by mass, more preferably 15 to 45% by mass, and particularly preferably 20 to 40% by mass. When the solation rate is less than 5% by mass, the binder fusion component decreases, which may lead to a decrease in work brittleness. When it exceeds 55% by mass, the binder fusion component increases, and the binder mobility is increased. Increases, the image storability may decrease.

  Here, the solification rate is a value calculated as follows.

  25 g of a polymer sample is weighed in an aluminum foil petri dish and dried at 60 ° C. for 2 hours with a blow dryer. The obtained dried film is further dried at 120 ° C. for 0.5 hour and cut to about 2 × 2 cm. This is put into a wire mesh basket (300 mesh) and left in 60 ml of tetrahydrofuran (THF) for 16 hours or more. The basket taken out from THF is dried at 110 ° C. for 1 hour, the amount of sample remaining in the basket (gel content) is weighed, the solification rate (ratio of components other than the gel content), and the gelation rate (ratio of gel content) Is calculated. The solification rate is preferably controlled by adjusting the addition amount of a chain transfer agent described later. Specifically, the addition amount of the chain transfer agent with respect to the monomer is preferably 0.01 to 5% by mass and more preferably 0.1 to 3% by mass with respect to the total mass of the monomer.

  The polymer latex preferably has a mass average molecular weight of 10,000 to 200,000, more preferably 30000 to 150,000, and particularly preferably 40000 to 100,000. When the mass average molecular weight of the sol is less than 10,000, the binder's fusing property may be lowered and work brittleness may be deteriorated. When the sol exceeds 200,000, the binder's fusing component increases and the binder's mobility increases. Therefore, the image storage stability may be lowered. Here, the mass average molecular weight measurement of the sol portion of the polymer latex can be measured by gel permeation chromatography.

  The polymer latex preferably has a glass transition temperature (Tg) of the sol part of -30 ° C to 50 ° C, more preferably 0 ° C to 30 ° C, and particularly preferably 10 ° C to 25 ° C. When the glass transition temperature of the sol is less than −30 ° C., the mobility of the binder is increased, so that the image storability may be lowered. When the glass transition temperature is higher than 50 ° C., the fusibility of the binder is lowered and processing brittleness is reduced. May get worse.

  The polymer latex preferably has a glass transition temperature (Tg) in the range of −20 ° C. to 80 ° C., more preferably in the range of 0 ° C. to 70 ° C., and still more preferably in the range of 10 ° C. to 10 ° C. The range is 60 ° C. It is also possible to use a blend of two or more polymers as the binder. In this case, it is preferable that the weighted average Tg is in the above range in consideration of the composition. In the case of phase separation or having a core-shell structure, the Tg of each phase is preferably in the vapor range.

  This glass transition temperature (Tg) can be calculated by the following formula.

1 / Tg = Σ (X _i / Tg _i )
Here, it is assumed that n monomers from i = 1 to n are copolymerized in the binder. X _i is the mass fraction of the i-th monomer (ΣX _i = 1), and Tg _i is the glass transition temperature (absolute temperature) of the homopolymer of the i-th monomer. Here, Σ is the sum from i to n. The value of the glass transition point (Tg _i ) of each monomer homopolymer was the value of Polymer Handbook (3rd Edition) (by J. Brandrup, EH, Immergut (Wiley-Interscience, 1988)).

  There are no particular restrictions on the type of polymer latex, and acrylic resin, polyester resin, rubber resin (eg, conjugated diene copolymer), polyurethane resin, vinyl chloride resin, vinyl acetate resin, vinylidene chloride resin, polyolefin A hydrophobic polymer such as a resin or a copolymer thereof can be used. Among these, acrylic resins, polyester resins, rubber resins (for example, conjugated diene copolymer) and polyurethane resins are preferable, and acrylic resins and rubber resins (for example, conjugated diene copolymer) are more preferable.

  The polymer latex is particularly preferably selected as a homopolymer or copolymer independently and freely combined from the monomer groups (a) to (j) shown below, and at least a conjugated diene from the viewpoint of photographic properties and film quality. More preferred is a polymer obtained by copolymerization of In addition, there is no restriction | limiting in particular in the monomer unit which can be used, If it can superpose | polymerize by normal radical polymerization or an ionic polymerization method, it can use suitably.

<Monomer group>
(A)-(j)
(A) Conjugated dienes: 1,3-butadiene, isoprene, 1,3-pentadiene, 2-ethyl-1,3-butadiene, 2-n-propyl-1,3-butadiene, 2,3-dimethyl-1, 3-butadiene, 2-methyl-1,3-butadiene, 1-phenyl-1,3-butadiene, 1-α-naphthyl-1,3-butadiene, 1-β-naphthyl-1,3-butadiene, 2- Chloro-1,3-butadiene, 1-bromo-1,3-butadiene, 1-chloro-1,3-butadiene, 2-fluoro-1,3-butadiene, 2,3-dichloro-1,3-butadiene, 1,1,2-trichloro-1,3-butadiene, 2-cyano-1,3-butadiene, cyclopentadiene, etc.
(B) Olefin: ethylene, propylene, vinyl chloride, vinylidene chloride, 6-hydroxy-1-hexene, 4-pentenoic acid, methyl 8-nonenoate, vinyl sulfonic acid, trimethyl vinyl silane, trimethoxy vinyl silane, 1,4-divinyl Cyclohexane, 1,2,5-trivinylcyclohexane, etc.
(C) α, β-unsaturated carboxylic acid and salts thereof: acrylic acid, methacrylic acid, itaconic acid, maleic acid, sodium acrylate, ammonium methacrylate, potassium itaconate, etc.
(D) α, β-unsaturated carboxylic acid esters: alkyl acrylates (for example, methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, etc.), substituted alkyl acrylates (for example, 2-chloro Ethyl acrylate, benzyl acrylate, 2-cyanoethyl acrylate, etc.), alkyl methacrylate (eg, methyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, etc.), substituted alkyl methacrylate (eg, 2-hydroxyethyl methacrylate, glycidyl methacrylate) , Glycerol monomethacrylate, 2-acetoxyethyl methacrylate, tetrahydrofurfuryl meta Chryrate, 2-methoxyethyl methacrylate, polypropylene glycol monomethacrylate (polyoxypropylene added mole number = 2 to 100), 3-N, N-dimethylaminopropyl methacrylate, chloro-3-N, N, N-trimethyl Ammoniopropyl methacrylate, 2-carboxyethyl methacrylate, 3-sulfopropyl methacrylate, 4-oxysulfobutyl methacrylate, 3-trimethoxysilylpropyl methacrylate, allyl methacrylate, 2-isocyanatoethyl methacrylate, etc.), unsaturated dicarboxylic acid derivatives (For example, monobutyl maleate, dimethyl maleate, monomethyl itaconate, dibutyl itaconate, etc.), polyfunctional esters (for example, ethylene glycol diacrylate, Tylene glycol dimethacrylate, 1,4-cyclohexanediacrylate, pentaerythritol tetramethacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolethane triacrylate, dipentaerythritol pentamethacrylate, pentaerythritol hexaacrylate, 1,2, 4-cyclohexanetetramethacrylate, etc.)
(E) Amides of β-unsaturated carboxylic acid: for example, acrylamide, methacrylamide, N-methylacrylamide, N, N-dimethylacrylamide, N-methyl-N-hydroxyethylmethacrylamide, N-tertbutylacrylamide, N -Tert-octylmethacrylamide, N-cyclohexylacrylamide, N-phenylacrylamide, N- (2-acetoacetoxyethyl) acrylamide, N-acryloylmorpholine, diacetone acrylamide, itaconic acid diamide, N-methylmaleimide, 2-acrylamide- Methyl propane sulfonic acid, methylene bisacrylamide, dimethacryloyl piperazine, etc.
(F) Unsaturated nitriles: acrylonitrile, methacrylonitrile, etc.
(G) Styrene and its derivatives: styrene, vinyl toluene, p-tertbutyl styrene, vinyl benzoic acid, methyl vinyl benzoate, α-methyl styrene, p-chloromethyl styrene, vinyl naphthalene, p-hydroxymethyl styrene, p- Styrene sulfonic acid sodium salt, p-styrene sulfinic acid potassium salt, p-aminomethyl styrene, 1,4-divinylbenzene, etc.
(H) Vinyl ethers: methyl vinyl ether, butyl vinyl ether, methoxyethyl vinyl ether, etc.
(I) Vinyl esters: vinyl acetate, vinyl propionate, vinyl benzoate, vinyl salicylate, vinyl chloroacetate, etc.
(J) Other polymerizable monomers: N-vinylimidazole, 4-vinylpyridine, N-vinylpyrrolidone, 2-vinyloxazoline, 2-isopropenyloxazoline, divinylsulfone, and the like.

  Preferred examples of the polymer obtained by copolymerizing at least a conjugated diene include styrene-butadiene copolymers (for example, butadiene-styrene block copolymers, styrene-butadiene-styrene block copolymers, etc.), styrene-isoprene copolymers. (For example, random copolymer, block copolymer, etc.), ethylene-propylene-diene copolymer (for example, 1,4-hexadiene, dicyclopentadiene, ethylidene norbornene, etc. as the diene monomer), acrylonitrile-butadiene copolymer Polymer, isobutylene-isoprene copolymer, butadiene-acrylic acid ester copolymer (for example, acrylic acid esters such as ethyl acrylate and butyl acrylate), and butadiene-acrylic acid ester-acrylonitrile copolymer (Ak The Le esters may be mentioned the ones available similar to) Among these, styrene - butadiene copolymer is most preferable.

  Specific examples of the polymer latex (compounds (P-1) to (P-29)) are given below.

  The molecular weight is a mass average molecular weight, and in the case of a polyfunctional monomer, the concept of molecular weight is not applicable, and thus description thereof is omitted. X, y, z, and z ′ in the polymer main chain portion in the chemical formula indicate the mass ratio of the polymer composition, and the sum of x, y, z, and z ′ is 100%. Moreover, the numerical value on the lower right of the parenthesis existing in the polymer side chain portion in the chemical formula represents the degree of polymerization. Tg represents the glass transition temperature of the polymer. Table 1 shows various physical properties of these exemplary compounds (including comparative binders (RP-1) and (RP-2) described later). The chelate compound is used in the polymerization, and the concentration of the chelate compound represents the concentration of the chelate compound contained in the polymer latex by high performance liquid chromatography. The present invention is not limited to these specific examples.

  In addition, the detail of each abbreviation of the chelate compound described in Table 1 is as follows.

Chelate 1: Ethylenediamine tetraacetic acid 4 sodium Chelate 2: Ethylenediamine tetraacetic acid 2 ammonium salt Chelate 3: Diethylenetriamine 5 acetic acid Chelate 4: Diaminopropanol tetraacetic acid Chelate 5: Hydroxyethylenediamine triacetic acid Chelate 6: Ethylenediamine tetraacetic acid 2 potassium Chelate 7: 2-hydroxy Benzylethylenediamine diacetic acid chelate 8: nitrilotriacetic acid chelate 9: ethylenediamine tetraacetic acid 2 lithium lithium Each of the polymer latexes listed above can be easily obtained by an emulsion polymerization method or the like. In the emulsion polymerization method, for example, water or a mixed solvent of water and an organic solvent miscible with water (for example, methanol, ethanol, acetone, etc.) is used as a dispersion medium, and the monomer is 5 to 40% by mass with respect to the dispersion medium. Using 0.05 to 5% by mass of a polymerization initiator and 0.1 to 20% by mass of an emulsifier with respect to the mixture and the monomer, about 30 to 100 ° C., preferably 60 to 90 ° C. for 3 to 8 hours, The polymerization is carried out with stirring. Various conditions such as the dispersion medium, the monomer concentration, the initiator amount, the emulsifier amount, the dispersant amount, the reaction temperature, and the monomer addition method are appropriately set in consideration of the type of monomer used. Moreover, it is preferable to use a dispersing agent as needed.

  As the chain transfer agent, those described in Polymer Handbook (3rd Edition) (Wiley-Interscience, 1989) are preferable. Sulfur compounds are more preferred because they have high chain transfer ability and can be used in small amounts. Hydrophobic mercaptan chain transfer agents such as tert-dodecyl mercaptan and n-dodecyl mercaptan are particularly preferred.

  The initiator used in the emulsion polymerization method may be water-soluble and capable of generating radicals, preferably persulfates and water-soluble azo compounds, more preferably ammonium persulfate, sodium persulfate, potassium persulfate, and azobiscyanovaleric acid. .

  As the dispersant used in the emulsion polymerization method, any of an anionic surfactant, a nonionic surfactant, a cationic surfactant, and an amphoteric surfactant can be used, but the anionic surfactant is dispersed. From the viewpoint of sex.

  In the emulsion polymerization method, in addition to the above compounds, electrolytes, stabilizers, thickeners, antifoaming agents, antioxidants, crosslinking agents, antifreezing agents, gelling agents, crosslinking accelerators, and other synthetic rubber handbooks etc. The described additives may be used.

  The emulsion polymerization method can be generally performed according to the following literature. “Synthetic Resin Emulsions (Edited by Taira Okuda, Hiroshi Inagaki, Published by Polymer Publishing Company (1978))”, “Application of Synthetic Latex (Takaaki Sugimura, Akio Kataoka, Junichi Suzuki, Keiji Kasahara, Published by Polymer Publishing Company (1993)) ”,“ Synthetic Latex Chemistry (written by Soichi Muroi, published by Kobunshi Shuppankai (1993)) ”.

  Hereinafter, although an example of the synthesis | combination of the polymer latex used for this invention is shown, it is not limited to this. Other exemplified compounds can be synthesized by the same synthesis method.

<Synthesis Example 1: Synthesis of Exemplified Compound P-1>
375.29 g of distilled water, a surfactant (Sandet BL (manufactured by Sanyo Chemical Co., Ltd.)), Asahi Kasei MICRO ACILYZER G3 (manufactured by pressure-resistant glass industry Co., Ltd., TAS-2J type) Membrane: Purified until AC110-800) no change in electrical conductivity: 13.61 g of solid content 27.6%), 14.06 ml of 1 mol / L NaOH aqueous solution, 0.14 ethylenediaminetetraacetic acid tetrasodium. 15 g, 258.75 g of styrene, 11.25 g of acrylic acid and 3.0 g of tert-dodecyl mercaptan were added, and the reaction vessel was sealed and stirred at a stirring speed of 200 rpm. After deaeration with a vacuum pump and nitrogen gas substitution was repeated several times, 105.0 g of 1,3-butadiene was injected and the internal temperature was raised to 60 ° C. A solution prepared by dissolving 1.875 g of ammonium persulfate in 50 ml of water was added thereto and stirred as it was for 5 hours. Furthermore, after raising the temperature to 90 ° C. and stirring for 3 hours and lowering the internal temperature to room temperature after completion of the reaction, the obtained polymer was filtered with a paper towel, and 812.2 g of the exemplified compound P-1 (solid content) 45%, particle size 95 nm, Tg 19 ° C.). When halogen ions were measured by ion chromatography, the chlorine ion concentration was 9 ppm. As a result of measuring the concentration of the chelating agent by high performance liquid chromatography, it was 150 ppm.

<Synthesis Example 2: Synthesis of Exemplified Compound P-2>
In a polymerization kettle of a gas monomer reaction apparatus (TAS-2J type manufactured by Pressure Glass Industry Co., Ltd.), 287 g of distilled water and surfactant (Pionin A-43-S (manufactured by Takemoto Yushi Co., Ltd.)): solid content 48. 5%) 7.73 g, 14.06 ml of 1 mol / L NaOH aqueous solution, 0.15 g of ethylenediaminetetraacetic acid tetrasodium salt, 255 g of styrene, 11.25 g of acrylic acid, and 3.0 g of tert-dodecyl mercaptan The reaction vessel was sealed and stirred at a stirring speed of 200 rpm. After degassing with a vacuum pump and repeating nitrogen gas replacement several times, 108.75 g of 1,3-butadiene was injected and the internal temperature was raised to 60 ° C. A solution prepared by dissolving 1.875 g of ammonium persulfate in 50 ml of water was added thereto, and the mixture was stirred as it was for 5 hours. Furthermore, after raising the temperature to 90 ° C. and stirring for 3 hours and lowering the internal temperature to room temperature after the completion of the reaction, the obtained polymer was filtered with a paper towel, and 774.7 g of Exemplified Compound P-2 (solid content) 45%, particle size 90 nm, Tg 17 ° C.). When halogen ions were measured by ion chromatography, the chlorine ion concentration was 3 ppm. As a result of measuring the concentration of the chelating agent by high performance liquid chromatography, it was 145 ppm.

<Synthesis Example 3: Synthesis of Exemplified Compound P-20>
In a glass three-necked flask equipped with a stirrer and a cooling tube, 296 g of distilled water and a surfactant (Sandet BL (manufactured by Sanyo Kasei Co., Ltd.)) were used at Asahi Kasei MICRO ACILYZER G3 (membrane: AC110-800). 10.89 g of the product refined until the conductivity does not change: solid content 27.6%), 15 ml of 1 mol / L NaOH aqueous solution, 0.3 g of nitrilotrihexaacetic acid, 135 g of methyl methacrylate, 150 g of butyl acrylate Then, 12 g of sodium styrenesulfonate, 3 g of methylbisacrylamide, and 2.4 g of tert-dodecyl mercaptan were added, and the mixture was stirred at a stirring speed of 200 rpm under a nitrogen stream, and the internal temperature was raised to 60 ° C. A solution prepared by dissolving 0.6 g of sodium persulfate in 40 ml of water was added thereto, and the mixture was stirred as it was for 5 hours. Furthermore, after raising the temperature to 90 ° C. and stirring for 3 hours and lowering the internal temperature to room temperature after the completion of the reaction, the obtained polymer was filtered with a paper towel to obtain 622 g of Exemplified Compound P-20 (45% solid content). , Particle size 108 nm, mass average molecular weight 140000, Tg 5 ° C.). When halogen ions were measured by ion chromatography, the chlorine ion concentration was 10 ppm. As a result of measuring the concentration of the chelating agent by high performance liquid chromatography, it was 450 ppm.

<Comparative Synthesis Example 1: Synthesis of Exemplified Compound RP-1>
In the synthesis of the polymer latex P-1, RP-1 (solid content 45%, particle size 80 nm) was synthesized in the same manner except that the surfactant was changed to PELEX SS-L (Kao Corporation). The chloride ion concentration was 400 ppm.

<Comparative Synthesis Example 2: Synthesis of Exemplary Compound RP-2>
In the synthesis of the polymer latex P-2, the surfactant was changed to PELEX SS-L (Kao Co., Ltd.), and except that ethylenediaminetetraacetic acid 4 sodium (chelate compound) was removed, RP-2 ( 44% solids, particle size 75 nm) was synthesized. The chloride ion concentration was 400 ppm.

  As the polymer latex, an aqueous solvent which is a solvent in the coating solution can be used, but it may be used in combination with a water-miscible organic solvent. Examples of the water-miscible organic solvent include alcohols such as methyl alcohol, ethyl alcohol and propyl alcohol, cellosolves such as methyl cellosolve, ethyl cellosolve and butyl cellosolve, ethyl acetate and dimethylformamide. The amount of these organic solvents added is preferably 50% or less, more preferably 30% or less of the solvent.

The addition amount of the polymer latex (binder) in the non-photosensitive organic silver salt content layer is such that the mass ratio of the total binder / organic silver salt is 1/10 to 10/1, and more preferably 1/5 to 4/1. preferable. Further, the non-photosensitive organic silver salt-containing layer is usually also a photosensitive layer (emulsion layer) containing a photosensitive silver halide that is a photosensitive silver salt. Is preferably in the range of 400 to 5, more preferably 200 to 10. Incidentally, the total amount of the binder in the image forming layer is preferably from 0.2 to 30 g / m ^2, more preferably in the range of 1 to 15 g / m ^2. A crosslinking agent for crosslinking, a surfactant for improving processing brittleness, and the like may be added to the image forming layer.

[Halogen precursor]
In the present invention, it is preferable to use a halogen precursor. The halogen precursor used in the present invention is a compound capable of releasing halogen by heat, light or the like. The halogen precursor is preferably an organic polyhalide having two or more halogen atoms on the same carbon atom. Examples thereof include JP-A Nos. 50-119624, 50-120328, and 51-121332. No. 54-58022, No. 56-70543, No. 56-99335, No. 59-90842, No. 61-129642, No. 62-129845, JP-A-6-208191. No. 6,208-193, No. 7-5621, No. 7-2781, No. 8-15809, US Pat. No. 5,340,712, No. 5,369,000. And those disclosed in US Pat. No. 5,464,737. Two or more types of halogen precursors may be used in combination.

  The halogen precursor used in the present invention may be dissolved in water or a suitable organic solvent, added to the coating solution, dried, and then present in a microcrystalline state in the film. As the organic solvent, alcohols (eg, methanol, ethanol, propanol, fluorinated alcohol, etc.), ketones (eg, acetone, methyl ethyl ketone, etc.), dimethylformamide, dimethyl sulfoxide, methyl cellosolve, etc. can be used. In addition, according to the well-known emulsion dispersion method, the halogen precursor is dissolved using an oil such as dibutyl phthalate, tricresyl phosphate, glyceryl triacetate, diethyl phthalate or the like, or an auxiliary solvent such as ethyl acetate or cyclohexanone. Alternatively, an emulsified dispersion may be prepared and used. Or, using a known dispersing machine such as a ball mill, a colloid mill, a sand mill, or a dispersing machine using ultrasonic waves, using a dispersion medium such as glass beads, zirconia beads, zircon silicate beads, etc. A fine solid dispersion may be prepared by dispersing in an appropriate solvent and added to the coating solution.

  The halogen precursor is preferably added as fine particles dispersed in water. When a fine solid dispersion is prepared and added in advance, it can be stably added with a uniform particle size, so that aggregation does not occur in the coating solution and performance does not fluctuate. When an aqueous dispersion of a thermoplastic resin is used as a binder, it is particularly preferable to add it as a solid dispersion. The average particle size of the halogen precursor particles in the solid dispersion is preferably 0.05 to 5 μm, more preferably 0.1 to 1 μm.

The addition amount of the halogen precursor is preferably 1 × 10 ^{−4 to} 1.0 mol or less, particularly 1 × 10 ^{−3 to} 5 × 10 ⁻¹ mol, relative to 1 mol of the organic silver salt of the image forming layer. preferable. If the amount added exceeds this range, the image density will decrease. If the amount added is too small, image fogging prevention and image stability will be insufficient.

  The halogen precursor may be added not only to the image forming layer but also to an undercoat layer, an intermediate layer and a protective layer described later.

[Silver carrier]
In the heat-developable image recording material of the present invention, it is preferable to use an additive for accelerating development, which has been conventionally called a “coloring agent” in the field of a heat-developable image recording method called a dry silver method. This additive acts on the non-photosensitive organic silver during heat development to form a diffusible silver complex, which is transported to the latent image nucleus and assists in the physical development using the latent image nucleus as a catalyst. Here, it is called a silver carrier. The silver carrier is preferably added in an amount of 0.1 to 50 mol%, more preferably 0.5 to 20 mol% per mol of the non-photosensitive organic silver in any layer on the side having the image forming layer of the support. Further, the silver carrier may be added as a precursor derivatized so as to have an effective function only during development. Silver carriers are disclosed in JP-A Nos. 46-6077, 47-10282, 49-5019, 49-5020, 49-91215, 50-2524, 50. No. -32927, No. 50-67132, No. 50-67641, No. 50-114217, No. 51-3223, No. 51-27923, No. 52-14788, No. 52-. No. 99813, No. 53-1020, No. 53-76020, No. 54-156524, No. 54-156525, No. 61-183642, JP-A-4-56848, JP-B-4949. -10727, 54-20333, U.S. Pat. Nos. 3,080,254, 3,446,648, No. 3,782,941, No. 4,123,282, No. 4,510,236, British Patent No. 1,380,795, Belgian Patent No. 841,910 It is disclosed as a toning agent in the specification and the like.

  Specific examples of the silver carrier include phthalimide and N-hydroxyphthalimide; succinimide, pyrazolin-5-one, quinazolinone, 3-phenyl-2-pyrazolin-5-one, 1-phenylurazole, quinazoline, 2,4- Cyclic imides such as thiazolidinedione; naphthalimides such as N-hydroxy-1,8-naphthalimide; cobalt complexes such as cobalt hexamine trifluoroacetate; 3-mercapto-1,2,4-triazole, 2,4-dimercapto Mercaptans such as pyrimidine, 3-mercapto-4,5-diphenyl-1,2,4-triazole, 2,5-dimercapto-1,3,4-thiadiazole; (N, N-dimethylaminomethyl) phthalimide, N, N- (dimethylaminomethyl) -naphthalene-2,3- N- (aminomethyl) aryl dicarboximide such as carboximide; photobleaching agents such as blocked pyrazole and isothiuronium derivatives (N, N′-hexamethylenebis (1-carbamoyl-3,5-dimethylpyrazole), 1, 8- (3,6-diazaoctane) bis (isothiuronium trifluoroacetate), 2- (tribromomethylsulfonyl) -benzothiazole, etc.); 3-ethyl-5-[(3-ethyl-2-benzothiazoli) Nylidene) -1-methylethylidene] -2-2,4-oxazolidinedione; 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethoxyphthalazinone, 2,3-dihydro-1 , 4-phthalazinedione. Phthalazinone and its derivatives or metal salts such as derivatives thereof; Combinations of phthalazinone and phthalic acid derivatives (phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid, tetrachlorophthalic anhydride, etc.); 4- (1-naphthyl) Phthalazine, 6-chlorophthalazine, 5,7-dimethoxyphthalazine, 6-isopropylphthalazine, 6-isobutylphthalazine, 6-tert-butylphthalazine, 5,7-dimethylphthalazine, 2,3-dihydrophthal Phthalazines such as azine and derivatives or metal salts thereof; combinations of phthalazine or its derivatives and phthalic acid derivatives (phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid, tetrachlorophthalic anhydride, etc.); quinazolinedione, benzoxazine and Naphthoxazine derivatives; hexachlorolodium Rhodium complexes that function not only as color control agents but also as halide ion sources for the formation of silver halide, such as (III) ammonium acid, rhodium bromide, rhodium nitrate and potassium hexachlororhodium (III); Inorganic peroxides and persulfates such as ammonium sulfide and hydrogen peroxide; 1,3-benzoxazine-2,4-dione, 8-methyl-1,3-benzoxazine-2,4-dione, 6-nitro Benzoxazine-2,4-diones such as -1,3-benzoxazine-2,4-dione; pyrimidines and asymmetric triazines such as 2,4-dihydroxypyrimidine and 2-hydroxy-4-aminopyrimidine; Dimercapto-1,4-diphenyl-1H, 4H-2,3a, 5,6a-tetraazapentalene, 1,4-di (o-chloroph Yl) -3,6-dimercapto -1H, 4H-2,3a, 5,6a- tetraazacyclododecane azauracil and tetraazapentalene derivatives pentalene like, and the like.

  Particularly preferred is a combination of phthalazine or a derivative thereof and a phthalic acid derivative (phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid, tetrachlorophthalic anhydride, etc.).

  These silver carriers are preferably added as an aqueous solution. However, when they are insoluble in water, they may be added in any state such as methanol solution, powder, solid fine particle dispersion and the like. The solid fine particle dispersion can be performed by a known finer means (for example, ball mill, vibration ball mill, sand mill, colloid mill, jet mill, roller mill, etc.). A dispersion aid may be used when dispersing the solid fine particles.

[Other various additives]
The heat-developable image recording material of the present invention may contain the additives described below. These additives may be added to layers other than the image forming layer, for example, an intermediate layer, a protective layer, a back layer, an undercoat layer and the like.

(Dispersion stabilizer)
Usually, the dispersion stabilizer is added during the preparation of the dispersion, and is additionally added during the preparation of the coating solution. An example of the dispersion stabilizer is a hydrophilic polymer, and preferable hydrophilic polymers include polyvinyl alcohol, methylcellulose, hydroxypropylcellulose, carboxymethylcellulose, hydroxypropylmethylcellulose and the like. The addition amount of the hydrophilic polymer is preferably 70% by mass or less, and more preferably 50% by mass or less, based on the solid content of the dispersion. The lower limit of the addition amount is not particularly limited, but is usually about 1% by mass.

  A surfactant can also be used as the dispersion stabilizer. The addition amount of the surfactant is preferably 50% by mass or less, more preferably 30% by mass or less, based on the solid content of the dispersion. The lower limit of the addition amount is not particularly limited, but is usually about 1% by mass.

(Surfactant to improve coatability)
The heat-developable image recording material of the present invention may contain a surfactant for improving coatability. The surfactant may be any of a nonionic surfactant, an anionic surfactant, a fluorine surfactant, and the like. Specifically, fluoropolymer surfactants described in JP-A-62-170950, US Pat. No. 5,380,644, etc., JP-A-60-244945, JP-A-63. -188135, etc., polysiloxane surfactants described in US Pat. No. 3,885,965, etc., polyalkylene oxides described in JP-A-6-301140, etc. Or an anionic surfactant can be used.

(Fluorine-containing surfactant)
It is preferable to add a fluorine-containing surfactant to the heat-developable image recording material of the present invention because good antistatic properties are obtained. Although it can add to arbitrary layers, adding to an outermost layer is especially preferable. Examples of preferred fluorine-containing surfactants have a fluoroalkyl group, fluoroalkenyl group or fluoroaryl group having 4 or more (usually 15 or less) carbon atoms, and an anionic group (for example, a sulfonic acid group, Sulfate groups, carboxylic acid groups, phosphoric acid groups, salts derived therefrom, etc.), cationic groups (eg amine salts, ammonium salts, aromatic amine salts, sulfonium salts, phosphonium salts etc.), betaine groups (eg carboxy Surfactants having an amine salt, a carboxyammonium salt, a sulfoamine salt, a sulfoammonium salt, a phosphoammonium salt, etc.) or a nonionic group (for example, a substituted or unsubstituted polyoxyalkylene group, polyglyceryl group or sorbitan residue). It is done. As for the fluorine-containing surfactant, JP-A-49-10722, British Patent 1,330,356, US Pat. No. 4,335,201, US Pat. No. 4,347,308 , British Patent No. 1,417,915, Japanese Patent Laid-Open Nos. 55-149938, 58-196544, British Patent No. 1,439,402, and the like.

You may use the said fluorine-containing surfactant in mixture of 2 or more types. The amount of the fluorine-containing surfactant used is preferably 0.0001 to 1 g, more preferably 0.0002 to 0.25 g, and particularly preferably 0.0003 to 0.1 g per 1 m ^{2 of} the image recording material.

(Dyes and pigments)
A dye or a pigment may be added to an arbitrary layer of the heat-developable image recording material of the present invention for the purpose of adjusting the color tone or preventing irradiation. Although these dyes and pigments are not particularly limited, for example, those described in the color index can be used. Specific examples thereof include pyrazoloazole dyes, anthraquinone dyes, azo dyes, azomethine dyes, oxonol dyes, carbocyanine dyes. , Styryl dyes, triphenylmethane dyes, indoaniline dyes, indophenol dyes, organic pigments such as phthalocyanine, and inorganic pigments. Among them, anthraquinone dyes (compounds 1 to 9 described in JP-A-5-341441, compounds 3-6 to 18 and 3-23 to 38 described in JP-A-5-165147), azomethine dyes (JP Compounds 17 to 47 described in JP-A-5-341441), indoaniline dyes (compounds 11 to 19 described in JP-A-5-289227, compound 47 described in JP-A-5-341441, and JP-A-5 And compounds 2-10 to 11 described in JP-A No. 165147) and azo dyes (compounds 10 to 16 described in JP-A No. 5-341441) can be preferably used.

  The amount of dye and pigment used may be selected according to the target absorption amount, but generally the optical absorption density at the exposure wavelength is 0.1 to 2.0, preferably 0.2 to 1.0. To be added. The dye and pigment may be added in any state, such as in the form of a solution, emulsion, solid fine particle dispersion, or mordanted in a polymer mordant. However, if the dye and pigment are water-soluble substances, they are added as an aqueous solution. If it is a water-insoluble substance, it is preferably added as a solid fine particle dispersion using water as a dispersion medium, and is added to the image forming layer, the layer between the image forming layer and the support, or the protective layer. .

(Sensitizing dye)
A sensitizing dye may be added to the image forming layer according to the present invention. The sensitizing dye is not particularly limited as long as it can spectrally sensitize the photosensitive silver halide grains in a desired wavelength region when adsorbed on the photosensitive silver halide grains, and may be a cyanine dye, a merocyanine dye, or a complex cyanine dye. Complex merocyanine dyes, holopolar cyanine dyes, styryl dyes, hemicyanine dyes, oxonol dyes, hemioxonol dyes and the like can be used. Sensitizing dyes described in RESEARCH DISCLOSURE Item 17643 IVA (December 1978, p. 23), Item 1831X (August 1979, p. 437) and references cited therein can also be used in the present invention.

  A preferred sensitizing dye for the present invention is one capable of spectrally sensitizing silver halide grains in the wavelength region of 500 nm or less when adsorbed on the silver halide grains, and has a spectral sensitivity suitable for the spectral characteristics of the exposure light source. The sensitive dye can be advantageously selected. These sensitizing dyes may be used alone or in combination of two or more.

  Of these sensitizing dyes, the sensitizing dyes represented by the general formulas (1) and (2) are preferably used.

In the general formula (1), Z ¹ and Z ² are unsubstituted or substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a phenyl group, and thiazoline To form a ring, thiazole ring, benzothiazole ring, naphthothiazole ring, selenazole ring, benzoselenazole ring, naphthselenazole ring, oxazole ring, benzoxazole ring, naphthoxazole ring, imidazole ring, benzimidazole ring or pyridine ring Represents a necessary group of non-metallic atoms, R ¹¹ and R ¹² represent an alkyl group having 1 to 4 carbon atoms, a hydroxyalkyl group, a carboxyalkyl group or a sulfoalkyl group, n1 and n2 represent 0 or 1, and X represents Represents an anion, and m1 represents 1 or 2.

The nonmetallic atom groups of Z ¹ and Z ² may be the same or different from each other as long as they can complete the above-described benzothiazole ring. Examples of the benzothiazole ring include benzothiazole, 5-chloro Benzothiazole, 5-methylbenzothiazole, 5-methoxybenzothiazole, 5-hydroxybenzothiazole, 5-hydroxy-6-methylbenzothiazole, 5,6-dimethylbenzothiazole, 5-ethoxy-6-methylbenzothiazole, 5 -Henylbenzothiazole, 5-carboxybenzothiazole, 5-ethoxycarbonylbenzothiazole, 5-dimethylaminobenzothiazole, 5-acetylaminobenzothiazole, etc. are mentioned. Examples of the benzoselenazole ring include benzoselenazole, 5-chlorobenzoselenazole, 5-methylbenzoselenazole, 5-methoxybenzoselenazole, 5-hydroxybenzoselenazole, and 5,6-dimethylbenzoselenazole. 5,6-dimethoxybenzoselenazole, 5-ethoxy-6-methylbenzoselenazole, 5-hydroxy-6-methylbenzoselenazole, 5-henylbenzoselenazole and the like, and as a naphthothiazole ring, For example, β-naphthothiazole, β, β-naphthothiazole and the like can be mentioned, and examples of the naphthoselenazole ring include β-naphthoselenazole and the like.

  Examples of the pyrroline ring include pyrroline and 1-methylpyrroline. Examples of the thiazoline ring include thiazoline and 4-methylthiazoline. Examples of the thiazole ring include thiazole, 4-methylthiazole, 4-phenylthiazole, 4,5-dimethylthiazole, 4-methyl-5-phenylthiazole and the like can be mentioned. Examples of the selenazole ring include selenazole, 4-methylselenazole, 4-phenylselenazole, 4,5- Examples of the oxazole ring include oxazole, 4-methyl oxazole, 5-methyl oxazole, 4,5-dimethyl oxazole, and 4-p-tolyl oxazole, and examples of the benzoxazole ring include For example, benzoxazo , 5-fluorobenzoxazole, 5-chlorobenzoxazole, 5-bromobenzoxazole, 5-trifluoromethylbenzoxazole, 5-methylbenzoxazole, 5-methyl-6-phenylbenzoxazole, 5,6-dimethylbenzoxazole , 5-methoxybenzoxazole, 5,6-dimethoxybenzoxazole, 5-phenylbenzoxazole, 5-carboxybenzoxazole, 5-methoxycarbonylbenzoxazole, 5-acetylbenzoxazole and the like, For example, β-naphthoxazole is exemplified, and examples of the imidazole ring include 1-methylimidazole, 1-ethylimidazole, 1-phenylimidazole, and the like. Examples of the imidazole ring include 1-methylbenzimidazole, 1-phenylbenzimidazole, 5-chloro-1-ethylbenzimidazole, 5-trichloromethyl-1-ethylbenzimidazole, and 5,6-dichloro-1-ethylbenzo. Imidazole, 5,6-dichloro-1-phenylbenzimidazole, 5-methoxycarbonyl-1-ethylbenzimidazole, 5-N, N-dimethylcarbamoyl-1-methylbenzimidazole, 5-N, N-diethylsulfamoyl Examples include -1-phenylbenzimidazole, 5-cyano-1-ethylbenzimidazole, and 5-cyano-1-β-hydroxyethylbenzimidazole. Examples of the pyridine ring include pyridine and 5-methylpyridine. It is done.

Specific examples of R ¹¹ and R ¹² include alkyl groups such as a methyl group, an ethyl group, and an n-propyl group, a β-hydroxyethyl group, a β-carboxyethyl group, a γ-carboxypropyl group, and a γ-sulfo group. Examples thereof include substituted alkyl groups such as propyl group, γ-sulfobutyl group, δ-sulfobutyl group, and δ-sulfoethoxyethyl group.

  Specific examples of the anion represented by X include a halogen ion, a perchlorine ring ion, a thiocyanate ion, a benzenesulfonate ion, a p-toluenesulfonate ion, and a methylsulfate ion.

In the general formula (2), Z ³ is unsubstituted or substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a phenyl group, a benzoxazole ring, Z ⁴ represents a nonmetallic atom group necessary for forming a thiazole ring, a benzothiazole ring, a selenazole ring, a benzoselenazole ring or a pyridine ring, and Z ⁴ represents a 2-thiohydratoin ring, a 2-thiooxazolidine-2,4′-dione ring Or a nonmetallic atom group necessary for forming a rhodanine ring, R ¹⁴ represents an alkyl group having 1 to 4 carbon atoms, a carboxyalkyl group, or a hydrogen atom, and R ¹⁵ represents an alkyl group having 1 to 4 carbon atoms or hydrogen. Represents an atom, and n3 represents 0 or 1.

Specifically, Z ³ is oxazole, 4-methyloxazole, 5-methyloxazole, 4,5-dimethyloxazole, 4-p-tolyloxazole, benzoxazole, 5-fluorobenzoxazole, 5-chlorobenzoxazole, 5- Bromobenzoxazole, 5-trifluoromethylbenzoxazole, 5-methylbenzoxazole, 5-methyl-6-phenylbenzoxazole, 5,6-dimethylbenzoxazole, 5-methoxybenzoxazole, 5,6-dimethoxybenzoxazole, 5-phenylbenzoxazole, 5-carboxybenzoxazole, 5-methoxycarbonylbenzoxazole, 5-acetylbenzoxazole, selenazole, 4-methylselenazole, 4-phenylselena 4,4-dimethylselenazole, benzoselenazole, 5-chlorobenzoselenazole, 5-bromobenzoselenazole, 5-methylbenzoselenazole, 5-methoxybenzoselenazole, 5,6-dimethylbenzoselena Sol, thiazole, 4-methylthiazole, 4-phenylthiazole, 4,5-dimethylthiazole, 4-methyl-5-phenylthiazole, benzothiazole, 5-chlorobenzothiazole, 5-bromobenzothiazole, 5-methylbenzothiazole 5-methoxybenzothiazole, 5-ethoxybenzothiazole, 6-methylbenzothiazole, 6-chlorobenzothiazole, 5-carboxybenzothiazole, 5-acetylbenzothiazole, 5-methoxycarbonylbenzothiazole, 5-hydro Xylbenzothiazole, 5-trifluoromethylbenzothiazole, 5-cyanobenzothiazole, 5,6-dimethylbenzothiazole, 5-acetylaminobenzothiazole, 6-methoxybenzothiazole, 5,6-dimethoxybenzothiazole, 5,6 -Dichlorobenzothiazole, naphtho [1,2-d] thiazole and the like.

  Next, specific examples of the compounds represented by the general formulas (1) and (2) used in the present invention will be shown, but the compounds represented by the general formulas (1) and (2) that can be used in the present invention are these. It is not limited to.

These sensitizing dyes can be added by the method described in paragraph No. [0106] of JP-A No. 11-119374, but is not particularly limited to this method. The addition amount of the sensitizing dye in the present invention can be set to a desired amount according to the sensitivity and fogging performance, but is preferably 1 × 10 ^{−6 to} 1 mol, more preferably 1 per 1 mol of the photosensitive silver halide. It is * 10 < ^-4 > ^-1 * 10 < ^-1 > mol.

In the present invention, a supersensitizer can be used to improve spectral sensitization efficiency. Supersensitizers used in the present invention are disclosed in European Patent Publication No. 587,338A, US Pat. Nos. 3,877,943 and 4,873,184. And compounds selected from compounds, heteroaromatic or aliphatic mercapto compounds, heteroaromatic disulfide compounds, stilbene, hydrazine, and triazine. Particularly preferred supersensitizers are heteroaromatic mercapto compounds, heteroaromatic disulfide compounds disclosed in JP-A-5-341432, and general formula (I) or (II) in JP-A-4-18239. A stilbene compound represented by general formula (I) of JP-A-10-111543, and a compound represented by general formula (I) of JP-A-11-109547. Specifically, compounds of M-1 to M-24 of JP-A-5-341432, compounds of d-1) to d-14) of JP-A-4-18239, and JP-A-10-111543. Compounds of SS-01 to SS-07, compounds of 31, 32, 37, 38, 41 to 45, 51 to 53 of JP-A-11-109547. The addition amount of these supersensitizers is preferably in the range of 1 × 10 ^{−4 to} 1 mol per mol of photosensitive silver halide, and more preferably in the range of 0.001 to 0.3 mol per mol of silver halide.

(Antifoggant, stabilizer and stabilizer precursor)
In the present invention, the generation of fog can be further suppressed by using an antifoggant, a stabilizer or a stabilizer precursor, the heat-developable image recording material can be stabilized, and a decrease in sensitivity during storage can be suppressed. . Antifoggants, stabilizers and stabilizer precursors may be used alone or in combination, examples of which include US Pat. Nos. 2,131,038 and 2,694. , 716; azaindene described in U.S. Pat. Nos. 2,886,437 and 2,444,605; U.S. Pat. No. 2,728,663. Described mercury salt; urazole described in US Pat. No. 3,287,135; sulfocatechol described in US Pat. No. 3,235,652; described in British Patent 623,448 Oximes, nitroso and nitroindazoles; polyvalent metal salts described in US Pat. No. 2,839,405; thiuonium salts described in US Pat. No. 3,220,839; US patents Palladium salts, platinum salts and gold salts described in US Pat. Nos. 2,566,263 and 2,597,915; US Pat. Nos. 4,108,665 and 4,442,202 Halogen-substituted organic compounds described in the specification; U.S. Pat. Nos. 4,128,557, 4,137,079, 4,138,365, and 4,459, And triazine described in US Pat. No. 350; and phosphorus compounds described in US Pat. No. 4,411,985.

(Mercapto compounds, disulfide compounds and thione compounds)
In the present invention, a mercapto compound, a disulfide compound or a thione compound is used for the purpose of suppressing or promoting development to control development, improving spectral sensitization efficiency, and improving storage stability before and after development. May be.

  The mercapto compound is preferably represented by Ar-SM or Ar-SS-Ar. Here, M is a hydrogen atom or an alkali metal atom, and Ar is a group containing an aromatic ring or condensed aromatic ring having one or more nitrogen atoms, sulfur atoms, oxygen atoms, selenium atoms or tellurium atoms. Ar is preferably a benzimidazole ring, naphthimidazole ring, benzothiazole ring, naphthothiazole ring, benzoxazole ring, naphthoxazole ring, benzoselenazole ring, benzotelrazole ring, imidazole ring, oxazole ring, pyrazole ring, triazole ring, Including thiadiazole ring, tetrazole ring, triazine ring, pyrimidine ring, pyridazine ring, pyrazine ring, pyridine ring, purine ring, quinoline ring or quinazolinone ring. These rings are halogen atoms (Br, C1, etc.), hydroxyl groups, amino groups, carboxyl groups, alkyl groups (preferably having 1 to 4 carbon atoms), alkoxy groups (preferably 1 to 4 carbon atoms). It may have a substituent selected from the group consisting of an atom having an atom) and an aryl group (which may further have a substituent).

  Specific examples of mercapto compounds include 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole, 2-mercapto-5-methylbenzimidazole, 6-ethoxy-2-mercaptobenzothiazole, 2,2 ′. -Dithiobis- (benzothiazole), 3-mercapto-1,2,4-triazole, 4,5-diphenyl-2-imidazolethiol, 2-mercaptoimidazole, 1-ethyl-2-mercaptobenzimidazole, 2-mercaptoquinoline 8-mercaptopurine, 2-mercapto-4 (3H) -quinazolinone, 7-trifluoromethyl-4-quinolinethiol, 2,3,5,6-tetrachloro-4-pyridinethiol, 4-amino-6- Hydroxy-2-mercaptopyrimi Monohydrate, 2-amino-5-mercapto-1,3,4-thiadiazole, 3-amino-5-mercapto-1,2,4-triazole, 4-hydroxy-2-mercaptopyrimidine, 2-mercaptopyrimidine, 4, 6-diamino-2-mercaptopyrimidine, 2-mercapto-4-methylpyrimidine hydrochloride, 3-mercapto-5-phenyl-1,2,4-triazole, 1-phenyl-5-mercaptotetrazole, 3- (5- Mercaptotetrazole) -sodium benzenesulfonate, N-methyl-N ′-{3- (5-mercaptotetrazolyl) phenyl} urea, 2-mercapto-4-phenyloxazole, 2- [3- (9-carbazolyl) Propylimino] -3- (2-mercaptoethyl) benzothiazoline, etc. Including but the invention is not limited thereto. The amount of these mercapto compounds used is preferably 0.0001 to 1.0 mol, more preferably 0.001 to 0.3 mol, per mol of silver in the image recording layer.

(Plasticizer)
In the present invention, a polyhydric alcohol (such as glycerin and diol described in US Pat. No. 2,960,404) may be used as a plasticizer.

(Hardener)
In the present invention, a hardener may be used. The hardener may be added to the image forming layer, protective layer, back layer, undercoat layer and the like. Examples of hardeners include polyisocyanates described in U.S. Pat. No. 4,281,060, JP-A-6-208193, and epoxy compounds described in U.S. Pat. No. 4,791,042. And vinyl sulfone compounds and oxazoline compounds described in JP-A No. 62-89048.

(Benzoic acids)
The present invention may contain benzoic acids for the purpose of increasing sensitivity and preventing fogging. Benzoic acids may be added to any layer of the heat-developable image recording material of the present invention, but are preferably added to the layer provided on the image-forming layer side of the support, and added to the image-forming layer or protective layer. It is preferable to do this. The benzoic acids used in the present invention are not particularly limited, but preferred examples include U.S. Pat. Nos. 4,784,939, 4,152,160, JP-A-9-329865, and U.S. Pat. -329864 gazette, 9-291737 gazette, etc. are mentioned.

  Benzoic acids may be added at any step of the coating solution preparation, and when added to the image recording layer, they may be added at any step from the organic silver salt preparation step to the coating solution preparation step, preferably organic silver. Add after salt preparation-just before application. Benzoic acids may be added in any state such as powder, solution, or fine particle dispersion. Moreover, you may add benzoic acid as a solution mixed with additives, such as a sensitizing dye, a reducing agent, and a color toning agent. The amount of benzoic acid added is preferably 1 μmol to 2 mol, more preferably 1 to 0.5 mol, per mol of total silver of the non-photosensitive organic silver and the photosensitive silver halide.

(Slip agent)
In the present invention, it is preferable to contain a slipping agent in the surface having the image forming layer of the support and / or the outermost surface layer on the opposite surface. The slip agent used in the present invention is not particularly limited as long as it is a compound that reduces the coefficient of friction of the surface when it is present on the surface of the object.

  Specific examples of the slip agent include U.S. Pat. No. 3,042,522, British Patent 955,061, U.S. Pat. No. 3,080,317, and 4,004,927. Silicone slipping agent described in the specification, US Pat. No. 4,047,958, US Pat. No. 3,489,567, British Patent 1,143,118, etc .; US Pat. No. 454,043, No. 2,732,305, No. 2,976,148, No. 3,206,311 and German Patent No. 1,284,295. Higher fatty acid type slip agent, alcohol type slip agent and acid amide type slip agent described in the specification, US Pat. No. 1,284,294, etc .; British Patent No. 1,263,722, US Pat. No. 3 , 933, 516 specification, etc .; US Pat. No. 2,588,765, US Pat. No. 3,121,060, British Patent 1,198,387, etc. The taurine type | system | group sliding agent etc. which are described in 3,502,473 specification, 3,042,222 specification, etc. are mentioned. Specific examples of the slip agent preferably used include cellosol 524 (main component carnauba wax), polylon A, 393 and H-481 (main component polyethylene wax), high micron G-110 (main component ethylene bis stearic acid amide), Hymicron G-270 (main component stearic acid amide) (manufactured by Chukyo Yushi Co., Ltd.) and the like. The amount of the slip agent used is preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, based on the amount of binder in the layer to be added.

[Back layer]
The back layer preferably contains a dye represented by the following general formulas (3) and (4), a base generator, and, if necessary, the following additives in the polymer binder. Further, the back layer may contain the fluorine-containing surfactant. The dye can be added to the layer on the back surface side of the support or the layer on the image recording layer side, but is preferably added to the layer on the back surface side.

(dye)
In the heat-developable image recording material of the present invention, it is preferable to use a dye represented by the following general formula (3) or (4).

In the general formulas (3) and (4), R ¹ is a hydrogen atom, an aliphatic group, an aromatic group, —NR ²¹ R ²⁶ , —OR ²¹ or —SR ²¹ , and R ²¹ and R ²⁶ are each independently Are a hydrogen atom, an aliphatic group or an aromatic group, or R ²¹ and R ²⁶ are combined to form a nitrogen-containing heterocycle. R ² is a hydrogen atom, an aliphatic group or an aromatic group, and L ¹ and L ² are each independently a substituted or unsubstituted methine group, and the methine group substituents are bonded to each other to form an unsaturated aliphatic group. A ring or an unsaturated heterocyclic ring may be formed. Z ¹ is an atomic group necessary for completing a 5-membered or 6-membered nitrogen-containing heterocyclic ring, and the nitrogen-containing heterocyclic ring may be condensed with an aromatic ring, and the nitrogen-containing heterocyclic ring and its condensed The ring may have a substituent. A represents an acidic nucleus, and B represents an aromatic group, an unsaturated heterocyclic group, or the following general formula (5). n and m each represent 1 or 2.

In the general formula (5), L ³ is a substituted or unsubstituted methine group, and may be bonded to L ² to form an unsaturated aliphatic ring or an unsaturated heterocyclic ring. R ³ represents an aliphatic group or an aromatic group. Z ² is an atomic group necessary for completing a 5-membered or 6-membered nitrogen-containing heterocyclic ring, and the nitrogen-containing heterocyclic ring may be condensed with an aromatic ring, and the nitrogen-containing heterocyclic ring and its condensed The ring may have a substituent.

In the general formulas (3) and (4), R ¹ is preferably —NR ²¹ R ²⁶ , —OR ²¹ , or —SR ²¹ . R ²¹ is preferably an aliphatic group or an aromatic group, and more preferably an alkyl group, a substituted alkyl group, an aralkyl group, a substituted aralkyl group, an aryl group or a substituted aryl group. R ²⁶ is preferably a hydrogen atom or an aliphatic group, more preferably a hydrogen atom, an alkyl group or a substituted alkyl group. The nitrogen-containing heterocyclic ring formed by combining R ²¹ and R ²⁶ is preferably a 5-membered ring or a 6-membered ring. The nitrogen-containing heterocycle may have a hetero atom other than nitrogen (eg, oxygen atom, sulfur atom).

  Examples of the aliphatic group include an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an alkynyl group, a substituted alkynyl group, an aralkyl group, and 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 preferable, and an alkyl group, a substituted alkyl group, an aralkyl group or a substituted aralkyl group is more preferable. A chain aliphatic group is preferred to a cyclic aliphatic group. The chain aliphatic group may have a branch. The number of carbon atoms in the alkyl group is preferably 1-30, more preferably 1-20, and still more preferably 1-15. The alkyl part of the substituted alkyl group is the same as in the case of 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. The number of carbon atoms in the aralkyl group is preferably 7 to 35, more preferably 7 to 25, more preferably 7 to 25, and still more preferably 7 to 20. The aralkyl part of the substituted aralkyl group is the same as the aralkyl group. Examples of substituents for aliphatic groups (eg, substituted alkyl groups, substituted alkenyl groups, substituted alkynyl groups, substituted aralkyl groups) include halogen atoms (eg, fluorine atoms, chlorine atoms, bromine atoms), hydroxyl groups, alkoxy groups , Aryloxy group, silyloxy group, heterocyclic oxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, nitro group, sulfo group, carboxyl group, acyl group, alkoxycarbonyl group, aryloxycarbonyl Group, carbamoyl group, alkylthiocarbonyl group, heterocyclic group, cyano group, amino group (including anilino group), acylamino group, aminocarbonylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfamoylamino group Alkyl and arylsulfonylamino groups, mercapto groups, alkylthio groups, arylthio groups, heterocyclic thio groups, sulfamoyl groups, alkyl and arylsulfinyl groups, alkyl and arylsulfonyl groups, alkoxycarbonyl groups, imide groups, phosphino groups, phosphinyl groups, phosphinyl groups A finyloxy group, a phosphinylamino group, and a silyl group are included. The carboxyl group and the sulfo group may be in a salt state. The cation that forms a salt with the carboxyl group and the sulfo group is preferably an alkali metal ion (for example, sodium ion or potassium ion).

  In addition, examples of the aromatic group include an aryl group and a substituted aryl group. The number of carbon atoms of the aryl group is preferably 6-30, more preferably 6-20, and still more preferably 6-15. The aryl part of the substituted aryl group is the same as the aryl group. Examples of the substituent of the aromatic group (substituted aryl group) include those exemplified in the examples of the aliphatic group and the substituent of the aliphatic group.

In the general formulas (3) and (4), R ² is a hydrogen atom, an aliphatic group or an aromatic group. The aliphatic group and the aromatic group are as described above. R ² is preferably a hydrogen atom or an aliphatic group, more preferably a hydrogen atom or an alkyl group, still more preferably a hydrogen atom or an alkyl group having 1 to 15 carbon atoms, Most preferably it is.

In the general formulas (3), (4), and (5), L ¹ , L ^2, and L ³ are each independently a methine group that may be substituted. Examples of the substituent for the methine group include a halogen atom, an aliphatic group, and an aromatic group. The aliphatic group and the aromatic group are 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 over an unsaturated heterocyclic ring. The ring to be formed is preferably a 5-membered ring or a 6-membered ring, and more preferably a cyclopentene ring or a cyclohexene ring. It is particularly preferred that the methine is unsubstituted or forms a cyclopentene ring or a cyclohexene ring.

  In the general formula (3), n represents 1 or 2, but is preferably 1. When n is 2, the methine group is repeated but need not be identical. In the general formula (4), m represents 1 or 2, but is preferably 1. When m is 2, methine groups are repeated but they need not be identical.

In the general formulas (3) and (4), Z ¹ is an atomic group that forms a 5-membered or 6-membered nitrogen-containing heterocycle. Examples of the nitrogen-containing heterocycle include an oxazole ring, thiazole ring, selenazole ring, pyrrole ring, pyrroline ring, imidazole ring and pyridine ring. A 5-membered ring is preferred over a 6-membered ring. The nitrogen-containing heterocycle may be condensed with an aromatic ring (for example, a benzene ring or a naphthalene ring). The nitrogen-containing heterocycle and its condensed ring may have a substituent. Examples of the substituent include the above-described aromatic substituents, but preferably a halogen atom (for example, fluorine atom, chlorine atom, bromine atom), hydroxyl, nitro, carboxyl, sulfo, alkoxy, aryl A group and an alkyl group. Carboxyl and sulfo may be in a salt state. The cation forming a salt with carboxyl and sulfo is preferably an alkali metal ion (for example, sodium ion or potassium ion).

  In the general formula (3), B represents an aromatic group, an unsaturated heterocyclic group, or the general formula (5). The definition of the aromatic group is as described above. The aromatic group represented by B is preferably a substituted or unsubstituted phenyl group, and the substituent is a halogen atom, amino group, acylamino group, alkoxy group, aryloxy group, alkyl group, alkylthio group, aryl group. And an amino group, an acylamino group, an alkoxy group, and an alkyl group are particularly preferable at the 4-position. The unsaturated heterocycle represented by B is preferably a 5- or 6-membered heterocyclic group composed of carbon, oxygen, nitrogen, and sulfur atoms. Of these, a 5-membered ring is particularly preferred. Preferred examples include substituted, unsubstituted pyrrole, indole, thiophene, and furan.

Z ² in the general formula (5) is an atomic group forming a 5-membered or 6-membered nitrogen-containing heterocyclic ring, and may be the same as or different from Z ¹ . Examples of the nitrogen-containing heterocyclic ring can include the same group as Z ¹ described above. R ³ represents an aliphatic group or an aromatic group, and is preferably an aliphatic group, and most preferably is —CHR ² (COR ¹ ), which is a substituent on the nitrogen atom of the general formula (3). preferable.

  In the general formula (4), A represents an acidic nucleus. As the acidic nucleus, a cyclic ketomethylene compound or a compound having a methylene group sandwiched between electron-withdrawing groups is preferable. Examples of cyclic ketomethylene compounds include 2-pyrazolin-5-one, rhodanine, hydantoin, thiohydantoin, 2,4-oxazolidinedione, isoxazolone, barbituric acid, indandione, dioxopyrazolopyridine, melodrum acid, Examples thereof include hydroxypyridine, pyrazolidinedione, 2,5-dihydrofuran-2-one, and pyrrolin-2-one. These may have a substituent.

A compound having a methylene group sandwiched between electron-withdrawing groups can be represented as Z ¹ CH ₂ Z ² , where Z ¹ and Z ² are —CN, —SO ₂ R ¹ , —COR ¹ , — _{^{COOR 2, -CONHR 2, -SO 2}} NHR 2, -C {= C (CN) 2} R 1, represents a _{-C {= C (CN) 2} } NHR 1, R 1 is an alkyl group, an aryl group, a heterocyclic group, R ² represents a group wherein a hydrogen atom, represented by R ^1, and R ^1, R ² may have a substituent.

  Among these acidic nuclei, 2-pyrazolidine-5-one, isoxazolone, barbituric acid, indandione, hydroxypyridine, pyrazolidinedione, and dioxopyrazolopyridine are more preferable.

The dye represented by the general formula (3) preferably forms a salt with an anion. When the dye represented by the general formula (3) has an anionic group such as carboxyl or sulfo as a substituent, the dye can form an inner salt. In other cases, the dye preferably forms a salt with the extramolecular anion. The anion is preferably monovalent or divalent, and more preferably monovalent. Examples of anions include halogen ions (Cl, Br, I), p-toluenesulfonate ions, ethylsulfate ions, 1,5-disulfonaphthalene dianions, PF ₆ , BF ₄ and ClO ₄ .

  Specific examples of the dyes represented by the general formulas (3) and (4) are shown below, but the compounds that can be used in the present invention are not limited by these specific examples.

(Base precursor)
The dye or salt thereof used in the present invention can be decolored by allowing a base to act under heating conditions. In the dye used in the present invention, the active methylene group in the dye is deprotonated by the action of the base, and the nucleophilic species generated thereby nucleophilically attacks the methylene chain in the molecule to form an intramolecular ring-closed product. Discolor. Accordingly, any base that can be used for this reaction can be any base that can deprotonate the active methylene group in the dye. The number of ring members newly formed by the intramolecular ring-closing reaction is not limited, but is preferably a 5- to 7-membered ring, and more preferably a 5- to 6-membered ring. The substantially colorless compound formed in this way is a stable compound and does not return to the original dye. Therefore, in the present invention, there is no problem in that the color erased by the color erasing method is restored.

  The heating temperature in the decoloring reaction is preferably 40 to 200 ° C, more preferably 80 to 150 ° C, and still more preferably 100 to 130 ° C. The heating time is preferably 1 to 120 seconds, more preferably 5 to 60 seconds, and further preferably 10 to 30 seconds.

  If a base is added to the back layer together with the dye, they react with each other during storage and lose their halation-preventing function, so it is desirable to use the base as a thermal decomposition precursor. Accordingly, the heat development temperature and time are determined in consideration of the time required for image formation and the time required for base generation and decoloration.

  The base necessary for the decoloring reaction is a broad base, and includes a nucleophile (Lewis base) in addition to a narrow base. When the base coexists with the dye, the decoloring reaction proceeds slightly even at room temperature. Therefore, it is desirable to keep the base physically or chemically isolated from the dye and to contact (react) the base and the dye during heating. Examples of the physical separation of the base include the use of microcapsules, encapsulating a hot-melt material in fine particles, or addition to different layers. Microcapsules include those that burst by pressure and those that burst by heating. Since the decoloring reaction is carried out under heating conditions, it is convenient to use microcapsules that burst when heated (thermally responsive microcapsules). For isolation, either the base or the dye is encapsulated in microcapsules. When the outer shell of the microcapsule is opaque, it is preferable to enclose a base. The heat-responsive capsule is described in Hiroyuki Moriga, Introductory / Special Paper Chemistry (Showa 50), and JP-A-1-150575. A base or a dye may be added to the fine particles of a hot-melt material such as wax. The melting point of the hot-melt material is between room temperature and the aforementioned heat development heating temperature. In the light-sensitive material, when a layer containing a dye and a layer containing a base are separated, it is preferable to provide a barrier layer containing a hot-melt material between these layers.

  The chemical isolation means are easier to implement and are preferred than the physical isolation means. The chemical isolation means is typically the use of a base precursor. There are various types of base precursors, but since the decoloring reaction is carried out under heating conditions, it is convenient to use a type of precursor that generates (or releases) a base by heating. A typical precursor that generates a base by heating is a pyrolytic (decarboxylation) 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 an aromatic group (aryl or saturated heterocyclic group) that promotes decarboxylation as a substituent. The base precursor of sulfonyl acetate is described in JP-A-59-168441, and the base precursor of propiolic acid is described in JP-A-59-180537. The base side component of the decarboxylated base presser 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 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. A precursor of a dioxygen base, a triacid base or a tetraacid base of a 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 group that combines the two amidine or guanidine moieties. Consisting 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 dye can be included in the image recording material in the form of a molecule, emulsion dispersion, or solid fine particle dispersion. In the case of molecular dispersion, a dye solution is added to the coating solution. When dispersed in the form of solid fine particles, a dispersion of solid fine particles of dye is prepared and then added to the coating solution.

  The amount of dye added is generally such that the optical density (absorbance) exceeds 0.1 when measured at the target wavelength. Practically, the addition amount is adjusted so that the optical density is preferably 0.3 to 3.0, more preferably 0.3 to 2.0, and still more preferably 0.3 to 1.5. Good.

  The amount of the base precursor used is preferably 1 to 100 times, more preferably 3 to 30 times that of the dye in terms of mol ratio. The base precursor is preferably added in the form of solid fine particles.

  Two or more compounds may be used in combination for both the dye and the base precursor. In particular, in order to adjust the melting point to a desired region, it is preferable to mix those having different melting points.

(Back layer binder)
The back layer may contain a binder, and the binder used for the back layer is preferably transparent or translucent and colorless. The binder may be a natural polymer, a synthetic resin, a synthetic polymer, a synthetic copolymer, a medium for forming a film, and examples thereof include gelatin, gum arabic, polyvinyl alcohol, hydroxyethyl cellulose, cellulose acetate, cellulose acetate butyrate, Polyvinylpyrrolidone, casein, starch, polyacrylic acid, polymethylmethacrylic acid, polyvinyl chloride, polymethacrylic acid, copoly (styrene-maleic anhydride), copoly (styrene-acrylonitrile), copoly (styrene-butadiene), polyvinylacetals (Polyvinyl formal, polyvinyl butyral, etc.), polyesters, polyurethanes, phenoxy resins, polyvinylidene chloride, polyepoxides, polycarbonates, polyvinyl acetate DOO, cellulose esters, polyamides, and the like.

The back layer may contain a polymer latex used for the image recording layer, and the glass transition temperature of the polymer latex used for the back layer (particularly the outermost layer) is preferably 25 to 100 ° C. The binder amount of the back layer is preferably 0.01 to 10 g / m ^2, more preferably from 0.5 to 5 g / m ^2.

(Matting agent for back layer)
In order to reduce the Beck seconds, it is preferable to add a matting agent to the back layer. The Beck smoothness is preferably 10 to 2000 seconds, more preferably 50 to 1500 seconds, and the particle size and addition amount of the matting agent may be changed in order to obtain such Beck smoothness. The Beck smoothness is obtained according to JIS P 8119 or TAPPIT479.

(Other)
The heat-developable image recording material of the present invention may have non-photosensitive layers such as an intermediate layer and a protective layer in addition to the image forming layer. Various auxiliary layers such as a back layer may be provided on the side of the support opposite to the image forming layer.

[Middle layer]
In the heat-developable image recording material of the present invention, it is preferable to provide an intermediate layer in order to solve the problem when the protective layer is directly provided with the image forming layer. An intermediate layer is included to solve coating failures that disturb the interface due to a large pH difference between the protective layer and the image forming layer, and to include some additives that have adverse interactions with each other when added to the image forming layer. It can be preferably used. Examples of agents that can be added include additives such as reducing agents, halogen precursors, silver carriers, dyes, pigments, development accelerators, development inhibitors, image stabilizers, dispersion stabilizers, crosslinking agents, plasticizers, and benzoic acids. Can be mentioned. As the binder for the intermediate layer, gelatin, polyvinyl alcohol, other synthetic polymers, and the like can be used in addition to the polymer soluble in the organic solvent used in the image recording layer and the aqueous polymer latex. The thickness of the intermediate layer is preferably 0.01 to 30 μm, more preferably 0.05 to 10 μm.

[Protective layer]
The heat-developable image recording material of the present invention is preferably provided with a protective layer made of a polymer binder or the like in order to protect the material surface. The protective layer is provided on the outer layer of the surface having the image forming layer of the support.

As the polymer binder, an organic solvent-soluble polymer or an aqueous polymer latex used in the image forming layer can be used. In the case of a polymer latex, the glass transition temperature of the polymer is preferably 25 to 100 ° C. In addition to the polymer latex, gelatin, polyvinyl alcohol, other synthetic polymers, and the like can also be used as a binder for the protective layer. The addition amount of the binder is preferably the area of the protective layer is 0.2 to 10 g / m ^2, more preferably 1 to 5 g / m ^2.

  The protective layer may contain additives such as a reducing agent, a halogen precursor, a dispersion stabilizer, a crosslinking agent, a surfactant for improving coating properties and adjusting the chargeability, benzoic acids, a hardener, and a slip agent. . The preferred embodiments of these additives are basically the same as those in the case of the image recording layer. The thickness of the protective layer is preferably 0.01 to 30 μm, more preferably 0.05 to 10 μm.

  It is desirable to add an inorganic or organic matting agent to the protective layer in order to prevent adhesion failure when the heat-developable image recording materials are overlaid.

  Examples of the matting agent include US Pat. Nos. 1,939,213, 2,701,245, 2,322,037, and 3,262,782. , US Pat. No. 3,539,344, US Pat. No. 3,767,448, etc., US Pat. No. 1,260,772, US Pat. No. 2,192, No. 241, No. 3,257,206, No. 3,370,951, No. 3,523,022, No. 3,769,020, etc. Examples of the inorganic matting agent are described. Specifically, water-dispersible vinyl polymers (for example, polymethyl acrylate, polymethyl methacrylate, polyacrylonitrile, acrylonitrile-α-methylstyrene copolymer, polystyrene, styrene-divinylbenzene copolymer, polyvinyl acetate, polyethylene carbonate , Polytetrafluoroethylene, etc.), cellulose derivatives (eg, methylcellulose, cellulose acetate, cellulose acetate propionate, etc.), starch derivatives (eg, carboxy starch, carboxynitrophenyl starch, urea-formaldehyde-starch reactant, etc.), publicly known Organic compounds such as gelatin hardened with a hardener and coacervate hardened gelatin into hard capsules, silicon dioxide, titanium dioxide, magnesium dioxide, oxidation Aluminum, can be barium sulfate, calcium carbonate, desensitizing the silver chloride and silver bromide in a known manner, glass, inorganic compounds such as diatomaceous earth preferably used as matting agents. The matting agents may be used alone or in combination. Various shapes such as a spherical shape, a rod shape, a needle shape, a scale shape, and an indefinite shape can be selected.

  The matting agent has an effect of preventing adhesion failure by forming irregularities on the surface of the protective layer to reduce the contact area. Accordingly, it is preferable that the average particle size is larger than the thickness of the protective layer, but it is sufficient if it is small as long as it forms an aggregate and protrudes from the surface. The average particle size of the matting agent is preferably 1 to 20 μm. If the average particle size is less than 1 μm, it is not practical, and if it exceeds 20 μm, the risk of sinking into the image forming layer and hindering image formation to give pinholes increases. Further, the particle size distribution of the matting agent is desirably narrow, and the monodispersity is preferably 10% or less. When there are a plurality of protective layers, the matting agent is preferably added to the outermost surface layer or a layer as close as possible to the outer surface.

  The protective layer preferably contains the fluorine-containing surfactant. Even if the matting agent and the fluorine-containing surfactant are added to the back layer, a desired effect can be obtained. These may be added to one or both of the protective layer and the back layer, but at least the fluorine-containing surfactant is preferably added to the image forming layer side. A fluorine-containing surfactant can be overcoated on the protective layer.

  The pH of the protective layer varies depending on the additive, but is relatively low, pH 2-7. In the case of forming a plurality of protective layers, it is preferred that the layer close to the image forming layer has a pH of 4 to 7, and the far layer has a pH of 2 to 5. The protective layer may be composed of a plurality of layers. For example, it is composed of a protective lower layer for protecting images mainly composed of organic polymers, and a protective upper layer for preventing adhesion including matting agent, slip agent, fluorine-containing surfactant, etc. and improving surface slipperiness. You can do it.

(Undercoat layer)
The heat-developable image recording material of the present invention may have an undercoat layer described in US Pat. No. 5,051,335.

[Support]
The material of the support used in the present invention is not particularly limited, and typical examples thereof include polyester (for example, polyethylene terephthalate, polyethylene naphthalate, etc.), cellulose nitrate, cellulose ester, polyvinyl acetal, polycarbonate and the like. Among these, biaxially stretched polyester, particularly polyethylene terephthalate (PET), is preferable from the viewpoint of strength, dimensional stability, chemical resistance, and the like.

  The thickness of the support is preferably 90 to 500 μm as the base thickness excluding the undercoat layer described later. The support may be transparent or translucent or a white reflective support. As the white reflective support, one made of a polyester film kneaded with a white inorganic pigment can be used.

  It is preferable to provide an undercoat layer or a moisture-proof layer made of vinylidene chloride copolymer on both sides of the support. The vinylidene chloride copolymers may be used alone or in combination of two or more. The undercoat layer may contain a crosslinking agent, a matting agent and the like, and SBR, polyester, gelatin and the like may be added as a binder as necessary. Furthermore, the undercoat layer may contain the above-mentioned fluorine-containing surfactant. The thickness of the undercoat layer is preferably 0.01 to 5 μm, more preferably 0.05 to 1 μm. The thickness of the vinylidene chloride copolymer in the undercoat layer is preferably 0.3 μm or more, more preferably 0.3 to 4 μm.

  When using the above-mentioned biaxially stretched polyester as a support, the polyester is heated at 130 to 185 ° C. in order to alleviate internal strain remaining in the film during biaxial stretching and eliminate thermal shrinkage strain generated during heat development. It is preferable to perform the heat treatment. The heat treatment may be performed at a constant temperature or while raising the temperature, or may be performed in a roll form or while being conveyed in a web form. When heat-treating while transporting in a web shape, the transport tension of the support during the treatment is preferably relatively low, specifically 0.7 MPa or less, more preferably 0.4 MPa or less. . At this time, the lower limit of the transport tension is not particularly limited, but is usually about 0.05 MPa. The heat treatment is preferably performed after the support is subjected to a treatment for improving the adhesion to the image forming layer and the back layer, the formation of an undercoat layer, and the like. The heat shrinkage rate of the support after heat treatment is -0.03 to + 0.01% in the machine direction (MD) and 0 to 0.04 in the transverse direction (TD) in the case of 120 ° C. and 30 seconds of heating conditions. % Is preferred.

[Coating method]
In the heat-developable image recording material of the present invention, the coating dip coating, air knife coating, flow coating, and extrusion coating using a hopper described in U.S. Pat. Each of the constituent layers described can be applied. Also, two or more layers can be coated simultaneously by the methods described in US Pat. No. 2,761,791 and British Patent No. 837,095.

  Next, a heat-developable image forming method using the heat-developable image forming material of the present invention will be described.

  The heat-developable image recording material of the present invention can form an image by thermal development after exposure with light having a wavelength of 500 nm or less. Preferably, laser light having a wavelength peak in the region of 380 nm to 500 nm is used. Preferably, it exposes with a scanning laser exposure apparatus, and heat develops at the temperature of 100 to 150 degreeC. The heat-developable image recording material of the present invention can be used for super high contrast image formation suitable for printing plate making.

  When the heat-developable image recording material of the present invention is used as a mask when a printing plate is produced with a PS plate after heat development, the heat-developable image recording material after heat development has an exposure condition for the PS plate in a plate making machine. Information for setting and information for setting the plate making conditions such as the conveying conditions of the mask original and the PS plate are carried as image information. Accordingly, the concentration (use amount) of the above-mentioned irradiation dye, halation dye, and filter dye is limited to read them. Since these pieces of information are read by an LED or a laser, it is necessary that the Dmin (minimum concentration) in the wavelength region of the sensor is low and the absorbance is 0.3 or less. For example, the plate making machine S-FNRIII manufactured by Fuji Photo Film Co., Ltd. uses a light source having a wavelength of 670 nm as a detector and a barcode reader for detecting a registration mark. The plate making machine APML series manufactured by Shimizu Manufacturing Co., Ltd. uses a 670 nm light source as a barcode reader. That is, when the Dmin (minimum density) near 670 nm is high, the information on the film cannot be detected accurately, and as a result, work errors such as poor conveyance and poor exposure occur. Therefore, in order to read information with a light source of 670 nm, Dmin near 670 nm needs to be low, and the absorbance at 660 to 680 nm after heat development needs to be 0.3 or less. More preferably, it is 0.25 or less. Although there is no restriction | limiting in particular in the lower limit, Usually, it is about 0.10.

  In the present invention, as an exposure apparatus used for imagewise exposure, an exposure apparatus using a laser diode (LD) or a light emitting diode (LED) as a light source is generally preferably used. In particular, LD is more preferable in terms of high output and high resolution. Any of these light sources may be used as long as they can generate light having an electromagnetic spectrum in a target wavelength range. For example, in the case of LD, a dye laser, a gas laser, a solid laser, a semiconductor laser, or the like can be used. Of particular interest are modules or blue semiconductor lasers in which an SHG (Second Harmonic Generator) element and a semiconductor laser are integrated. High illuminance is generally performed with a short exposure time of 10-7 seconds or less.

  In the exposure in the present invention, exposure is performed by overlapping the light beams of the light sources. Overlap means that the sub-scanning pitch width is smaller than the beam diameter. The overlap can be expressed quantitatively by FWHM / sub-scanning pitch width (overlap coefficient), for example, when the beam diameter is expressed by the half width (FWHM) of the beam intensity. In the present invention, this overlap coefficient is preferably 0.2 or more.

  The scanning method of the light source of the exposure apparatus used in the present invention is not particularly limited, and a cylindrical outer surface scanning method, a cylindrical inner surface scanning method, a planar scanning method, and the like can be used. The channel of the light source may be a single channel or a multi-channel, but a multi-channel equipped with two or more laser heads is preferable in that a high output is obtained and a writing time is shortened. In particular, in the case of the cylindrical outer surface type, a multichannel equipped with several to several tens of laser heads is preferably used.

  The heat-developable image recording material of the present invention has a low haze upon exposure and tends to generate interference fringes. As a technique for preventing the generation of interference fringes, the technique disclosed in Japanese Patent Application Laid-Open No. 5-113548 is disclosed in a technique for obliquely entering a laser beam with respect to a photosensitive material, or in an international publication WO95 / 31754. There are known methods using multimode lasers, and these techniques are preferably used.

  The heat development step of the image forming method used in the present invention may be any method, but usually, the heat-developable image recording material exposed imagewise is heated and developed. As a preferred embodiment of the heat developing machine to be used, as a type in which the heat-developable image recording material is brought into contact with a heat source such as a heat roller or a heat drum, JP-B-5-56499, JP-A-9-292695 and JP-A-9- No. 297385 and International Publication WO95 / 30934 pamphlet, as non-contact type, Japanese Patent Application Laid-Open No. 7-13294, International Publication WO97 / 28489, 97/28488 and 97/28 There is a heat developing machine described in pamphlet No. 28487. A particularly preferred embodiment is a non-contact type heat developing machine. The preferred development temperature is 80 to 250 ° C, more preferably 100 to 150 ° C. The development time is preferably 1 to 180 seconds, and more preferably 5 to 90 seconds. The line speed is preferably 140 cm / min or more, more preferably 150 cm / min or more.

  As a method for preventing processing unevenness due to dimensional change of the heat-developable image recording material during heat development, after heating for 5 seconds or more so as not to produce an image at a temperature of 80 ° C. or higher and lower than 115 ° C., 110 ° C. to 140 ° C. It is effective to adopt a method (so-called multi-step heating method) in which an image is formed by heat development with the above method.

  When the heat-developable image recording material of the present invention is subjected to a heat development treatment, it is exposed to a high temperature of 100 ° C. or higher, so that a part of the components contained in the material or a part of the decomposition components by heat development is volatilized. Come. These volatile components cause uneven development, corrode heat developing machine components, precipitate at low temperatures, cause deformation of the screen as foreign matter, and adhere to the screen and become dirty. It is known that there are bad effects. As a method for removing these influences, it is known to install a filter in the heat developing machine and optimally adjust the air flow in the heat developing machine. These methods can be used effectively in combination. International publication WO95 / 30933 pamphlet, 97/21150 pamphlet, and Japanese translation of PCT publication No. 10-500496 have a first opening for introducing volatile matter and a second opening for discharging volatile matter. Is used in a heating device that heats the filter cartridge in contact with the film. In addition, International Publication WO 96/12213 pamphlet and Japanese National Publication No. 10-507403 disclose that a filter in which a heat conductive condensing collector and a gas absorbing fine particle filter are combined is used. In the present invention, these can be preferably used. In US Pat. No. 4,518,845 and Japanese Patent Publication No. 3-54331, a device for removing steam from a film, a pressure device for pressing the film against a heat transfer member, and a heat transfer member are heated. A device having a device to perform is described. In addition, International Publication WO 98/27458 pamphlet describes that a component that increases the fog that volatilizes from a film is removed from the film surface. These can also be preferably used in the present invention.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

《Preparation of underdrawn support》
Using terephthalic acid and ethylene glycol, polyethylene terephthalate (PET) having an intrinsic viscosity of IV = 0.66 (measured at 25 ° C. in phenol / tetrachloroethane = 6/4 (mass ratio)) 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-type die onto a 50 ° C. casting drum to which static electricity is applied, and the thickness after heat setting is 120 μm. An unstretched film was prepared. This was longitudinally stretched 3.3 times using rolls having different peripheral speeds and then stretched 4.5 times with a tenter. The temperatures at this time were 110 ° C. and 130 ° C., respectively. Then, after heat setting at 240 ° C. for 20 seconds, the film was relaxed by 4% in the lateral direction at the same temperature. Then, after slitting the chuck portion of the tenter, knurling with a thickness of 10 μm was applied to both ends with a width of 1 cm. In this way, a PET film having a width (film forming width) of 2.5 m was obtained.

Both sides of this PET film (thickness 120 μm) are subjected to a corona discharge treatment of 8 W / m ² · min, and the following undercoat coating solution a is applied to one side so that the dry film thickness is 0.8 μm and dried. Thus, the undercoat layer A was obtained. On the other side, the following undercoat coating solution b subjected to antistatic treatment was applied and dried so as to have a dry film thickness of 0.8 μm to form an antistatic undercoat layer B.

<Undercoat coating solution a>
Copolymer latex liquid having a solid content of 30% (butyl acrylate / tert-butyl acrylate / styrene / 2-hydroxyethyl acrylate = 30/20/25/25 (mass%)) 270 g
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
Water was added to make a total of 1 liter.

<Undercoat coating solution b>
SnO ₂ / Sb (mass ratio: 9/1 average particle size 0.18 μm)
200 mg / m ² to qs 30% solids copolymer latex solution (butyl acrylate / styrene / glycidyl acrylate = 30/20/40 (wt%)) 270 g
Hexamethylene-1,6-bis (ethylene urea) 0.8g
Water was added to make a total of 1 liter.

(Heat treatment of support)
<Low tension heat treatment>
In the undercoat drying step of the above-described undercoated support, low-tension heat treatment was performed for 45 seconds under the conditions of a heating temperature of 180 ° C. and a tension of 0.15 MPa.

<Post-heat treatment>
Subsequent to the low-tension heat treatment, it was passed through a zone of 40 ° C. for 15 seconds, followed by post-heat treatment and winding. The winding tension at this time was 1.0 MPa.

(Slitting)
The PET support (width 2.5 m) subjected to the above treatment was slitted with a width of 1.2 m and an offset amount of 16%. Next, a knurling having a width of 10 mm and a height of 10 μm was applied to both ends after the slit to produce a substrate 1 that had been subtracted.

<< Preparation of heat-developable image recording material 1 >>
[Formation of back layer and back protective layer]
(Preparation of solid fine particle dispersion (a) of base precursor)
64 g of the base precursor compound (BP-41) was mixed with 28 g of diphenylsulfone and 10 g of a surfactant (manufactured by Kao Corporation, Demol N) and 220 ml of distilled water, and the mixture was mixed with a sand mill (IMEX Co., Ltd.). Manufactured by a 1/4 Gallon Sand Grinder Mill) to obtain a solid fine particle dispersion (a) of a base precursor compound having an average particle size of 0.2 μm.

(Preparation of solid fine particle dispersion of base decoloring dye)
19.6 g of the base decoloring dye (Exemplary Compound (1)) and 5.8 g of sodium p-dodecylbenzenesulfonate were mixed with 305 ml of distilled water, and the mixture was mixed with Sand Mill (Imex Co., Ltd., 1/4). Using a Gallon sand grinder mill, beads were dispersed to obtain a dye solid fine particle dispersion having an average particle size of 0.2 μm.

(Preparation of back layer coating solution)
The following additives were sequentially mixed to prepare a back layer coating solution.

Gelatin 17g
9.6 g of polyacrylamide
70 g of a solid fine particle dispersion of a base precursor (a)
56 g of a solid fine particle dispersion of a base decoloring dye [Exemplary Compound (1)]
Matting agent: 1.5 g of monodispersed polymethyl methacrylate particles (average particle size: 8 μm)
Preservative: Benzisothiazolinone 0.03g
Polyethylene sulfonate sodium 2.2g
844 ml of water
(Preparation of back protective layer coating solution)
The container was kept at 40 ° C., and the following additives were sequentially mixed to prepare a back protective layer coating solution.

50g gelatin
Sodium polystyrene sulfonate 0.2g
N, N-ethylenebis (vinylsulfone acetamide) 2.4 g
1 g of sodium tert-octylphenoxyethoxyethanesulfonate
Benzoisothiazolinone 30mg
Fluorine-based surfactant (F-1: N-perfluorooctylsulfonyl-N-propylalanine potassium salt) 37 mg
Fluorine-based surfactant (F-2: polyethylene glycol mono (N-perfluorooctylsulfonyl-N-propyl-2-aminoethyl) ether [ethylene oxide average polymerization degree 15]) 0.15 g
Fluorine-based surfactant (F-3) 64mg
Fluorosurfactant (F-4) 32mg
Acrylic acid / ethyl acrylate copolymer (copolymerization mass ratio: 5/95) 8.8 g
Aerosol OT (American Cyanamid) 0.6g
Liquid paraffin emulsion 1.8g as liquid paraffin
950 ml of water

(Application of back layer and back protective layer)
The back layer coating liquid is applied to the back surface side of the prepared subtracted support 1 so that the solid content coating amount of the solid fine particle dye is 0.04 g / m ^2. A back coating layer and a back protection layer were provided by coating and drying at the same time so that the gelatin coating amount was 1.7 g / m ² .

<< Formation of image recording layer and protective layer >>
(Preparation of silver bromide emulsion A)
After dissolving 11 g of alkali-treated gelatin (calcium content of 2700 ppm or less), 30 mg of potassium bromide and 1.3 g of sodium 4-methylbenzenesulfonate in 700 ml of water and adjusting the pH to 6.5 at 40 ° C. , an aqueous solution 159ml containing silver nitrate 18.6 g, potassium bromide _{1mol / L, (NH 4)} 2 RhCl 5 (H 2 O) to 5 × 10 ^-6 mol / L and K ₃ IrCl ₆ to 2 × 10 ^{- An} aqueous solution containing ⁵ mol / L was added over 6 minutes 30 seconds by the control double jet method while maintaining pAg 7.7. Then, an aqueous solution 476ml containing silver nitrate 55.5 g, and a halogen salt aqueous solution containing 1 mol / L and ^{_{K 3 IrCl 6 2 × 10 -5}} mol / L of potassium bromide, the controlled double jet method while maintaining the pAg7.7 For 28 minutes and 30 seconds. Thereafter, the pH was lowered to cause coagulation sedimentation, followed by desalting, and 51.1 g of low molecular weight gelatin having an average molecular weight of 15,000 (calcium content of 20 ppm or less) was added to adjust the pH to 5.9 and pAg 8.0. The obtained silver halide grains were cubic silver bromide grains having an average grain size of 0.08 μm, a projected area variation coefficient of 9%, and a (100) plane ratio of 90%.

The silver halide grains thus obtained were heated to 60 ° C., 76 μmol of sodium benzenethiosulfonate per 1 mol of silver was added, 71 μmol of triethylthiourea was added after 3 minutes, and then ripened for 100 minutes. After adding 5 × 10 ⁻⁴ mol of 6-methyl-1,3,3a, 7-tetrazaindene and 0.17 g of compound A, the temperature was lowered to 40 ° C. Thereafter, the temperature was kept at 40 ° C., and an aqueous solution containing 1% by mass of benzothiazolium iodide with respect to 1 mol of silver halide was 7 × 10 ⁻³ mol, 4.7 × 10 ⁻² mol of potassium bromide (aqueous solution). And 3.0 × 10 ⁻³ mol of a spectral sensitizing dye (Exemplary Compound (I-6) added as a methanol solution) with stirring, and after 20 minutes, rapidly cooled to 30 ° C. Further, silver bromide emulsion A was prepared by adding water so that the amount of silver contained in 1 kg was 38.2 g.

(Preparation of fatty acid silver dispersion)
87.6 kg of behenic acid (manufactured by Henkel, product name Edenor C22-85R), 423 L of distilled water, 49.2 L of NaOH aqueous solution with a concentration of 5 mol / L, and 120 L of tert-butanol were mixed, and the reaction was stirred at 75 ° C. for 1 hour. To obtain a sodium behenate solution. Separately, 206.2 L (pH 4.0) of an aqueous solution containing 40.4 kg of silver nitrate was prepared and kept warm at 10 ° C. A reaction vessel containing 635 L of distilled water and 30 L of tert-butanol was kept at 30 ° C., and with sufficient stirring, the total amount of the previous sodium behenate solution and the total amount of silver nitrate aqueous solution were 93 minutes and 15 seconds at a constant flow rate, respectively. Added over 90 minutes. At this time, only the silver nitrate aqueous solution is added for 11 minutes after the start of the addition of the silver nitrate aqueous solution, and then the addition of the sodium behenate solution is started. After the addition of the silver nitrate aqueous solution, only the sodium behenate solution is added for 14 minutes and 15 seconds. Was added. At this time, the temperature in the reaction vessel was 30 ° C., and the external temperature was controlled so that the liquid temperature was constant. The piping of the sodium behenate solution addition system was maintained by circulating hot water outside the double pipe so that the liquid temperature at the outlet of the addition nozzle tip was 75 ° C. Moreover, the piping of the addition system of the silver nitrate aqueous solution was kept warm by circulating cold water outside the double pipe. The addition position of the sodium behenate solution and the addition position of the aqueous silver nitrate solution were arranged symmetrically around the stirring axis, and were adjusted so as not to contact the reaction solution.

  After completion of the addition of the sodium behenate solution, the mixture was left stirring for 20 minutes at the same temperature, heated to 35 ° C. over 30 minutes, and then aged for 210 minutes. Immediately after completion of aging, the solid content was separated by centrifugal filtration, and the solid content was washed with water until the conductivity of filtered water reached 30 μS / cm. Thus, a fatty acid silver salt was obtained. The obtained solid content was stored as a wet cake without drying.

  When the morphology of the obtained silver behenate particles was evaluated by electron microscope photography, it was a scaly crystal having an average projected area of 0.52 μm, an average particle thickness of 0.14 μm, and a sphere equivalent diameter variation coefficient of 15%.

  19.3 kg of polyvinyl alcohol (Kuraray Co., Ltd., trade name: PVA-217) and water are added to the wet cake corresponding to a dry solid content of 260 kg. Preliminarily dispersed with a line mixer (manufactured by Mizuho Kogyo Co., Ltd .: PM-10 type).

  Next, the pre-dispersed undiluted solution is adjusted to a pressure of 123 MPa for 3 cycles by using a disperser (manufactured by Microfluidics International Corporation, trade name: Microfluidizer M-610, using Z-type interaction chamber). Thus, a silver behenate dispersion was obtained. The cooling operation was set to a dispersion temperature of 18 ° C. by installing a serpentine heat exchanger before and after the interaction chamber and adjusting the temperature of the refrigerant.

(Preparation of reducing agent dispersion A)
10 kg of 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane and 16 kg of a 10% by weight aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) Then, 7.2 kg of water was added and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump and dispersed in a horizontal bead mill (IMM Co., Ltd., UVM-2) filled with zirconia beads having an average diameter of 0.5 mm for 4 hours 30 minutes, and then benzoisothiazolinone sodium salt 0.2 g and water were added to adjust the concentration of the reducing agent to 25% by mass to obtain a reducing agent dispersion A.

  The reducing agent particles contained in the reducing agent dispersion A thus obtained had a median diameter of 0.46 μm and a maximum particle diameter of 1.6 μm or less. The obtained reducing agent dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

(Preparation of solid fine particle dispersion of organic polyhalogen compound A)
10 kg of organic polyhalogen compound A, 10 kg of 20 wt% aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203), 639 g of 20 wt% aqueous solution of sodium triisopropyl naphthalenesulfonate, Surfynol 104E ( 400 g of Nissin Chemical Co., Ltd.), 640 g of methanol and 16 kg of water were added and mixed well to obtain a slurry. This slurry is fed with a diaphragm pump and dispersed for 5 hours in a horizontal bead mill (IMM Co., Ltd., UVM-2) filled with zirconia beads having an average diameter of 0.5 mm. Then, water is added to the organic polyhalogen compound. A concentration of A was adjusted to 25% by mass to obtain a solid fine particle dispersion of organic polyhalogen compound A. The organic polyhalogen compound particles contained in the solid fine particle dispersion of the organic polyhalogen compound A thus obtained had a median diameter of 0.36 μm, a maximum particle diameter of 2.0 μm or less, and an average particle diameter variation coefficient of 18%. The obtained dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

(Preparation of organic polyhalogen compound B dispersion)
5 kg of organic polyhalogen compound B, 2.5 kg of 20 wt% aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203), 213 g of 20 wt% aqueous solution of sodium triisopropylnaphthalenesulfonate, and 10 kg of water Add and mix well to make a slurry. This slurry was fed with a diaphragm pump and dispersed for 5 hours in a horizontal bead mill filled with zirconia beads having an average diameter of 0.5 mm (manufactured by Imex Co., Ltd., UVM-2), and then benzoisothiazolinone sodium salt2. 5 g and water were added so that the concentration of the organic polyhalogen compound B was 23.5% by mass to obtain a solid fine particle dispersion of the organic polyhalogen compound B. The organic polyhalogen compound particles contained in the solid fine particle dispersion of organic polyhalogen compound B thus obtained had a median diameter of 0.38 μm, a maximum particle diameter of 2.0 μm or less, and an average particle diameter variation coefficient of 20%. The obtained dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

(Preparation of 6-isopropylphthalazine compound dispersion)
While stirring 62.35 g of water at room temperature, 2.0 g of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) was added so as not to be agglomerated, and the mixture was stirred for 10 minutes. Then, after heating and heating up until internal temperature became 50 degreeC, it stirred for 90 minutes within the range of internal temperature 50-60 degreeC, and was dissolved uniformly. Next, the internal temperature was lowered to 40 ° C. or lower, 25.5 g of a 10% by weight aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co., Ltd., PVA-217), 3.0 g of a 20% by weight aqueous solution of sodium tripropylnaphthalenesulfonate, and 6.15 g of 6-isopropylphthalazine (70% by mass aqueous solution) was added and stirred for 30 minutes to obtain 100 g of a transparent dispersion. The obtained dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

(Preparation of solid fine particle dispersion of development accelerator W)
5 kg of the development accelerator W, 10 kg of a 20 mass% aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) and 20 kg of water were added and mixed well to obtain a slurry. This slurry is fed with a diaphragm pump, dispersed in a horizontal bead mill (IMM Co., UVM-2) filled with zirconia beads having an average diameter of 0.5 mm for 5 hours, and then added with water to develop accelerator W. The concentration of the toner was adjusted to 20% by mass to obtain a solid fine particle dispersion of the development accelerator W. The development accelerator particles contained in the solid fine particle dispersion of development accelerator W thus obtained had a median diameter of 0.4 μm, a maximum particle diameter of 2.5 μm or less, and an average particle diameter variation coefficient of 21%. The obtained dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

(Preparation of solid fine particle dispersion of super-hardening agent H)
To 4 kg of the super-hardening agent H, 1 kg of Poval PVA-217 manufactured by Kuraray Co., Ltd. and 36 kg of water were added and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump and dispersed for 12 hours in a horizontal bead mill filled with zirconia beads having an average diameter of 0.5 mm (manufactured by Imex Co., Ltd., UVM-2), and then 4 g of benzoisothiazolinone sodium salt and Water was added so that the concentration of the ultrahigh contrast agent H was 10% by mass to obtain a solid fine particle dispersion of the ultrahigh contrast agent H. The particles of the ultrahigh contrast agent contained in the solid fine particle dispersion of the ultrahigh contrast agent H thus obtained had a median diameter of 0.34 μm, a maximum particle size of 3.0 μm or less, and a variation coefficient of the particle size of 19%. The obtained dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

(Preparation of salicylic acid derivative dispersion A)
210 g of water was added to 30 g of salicylic acid derivative A, 30 g of modified polyvinyl alcohol (Kuraray Co., Ltd., MP-203), 0.6 g of sodium triisopropylnaphthalene sulfonate (Takemoto Yushi Co., Ltd., trade name: Leopold BX). And mixed well to prepare a slurry. This slurry was put in a vessel together with 960 g of dispersed beads (zirconia grains having an average diameter of 0.5 mm), and dispersed for 5 hours with a disperser sand mill (manufactured by IMEX Co., Ltd., 1 / 4G sand grinder mill). Subsequently, the dispersion was taken out by diluting with 105 g of water to obtain a salicylic acid derivative dispersion A having an average particle size of 0.4 μm.

(Preparation of coating solution)
<Preparation of image forming layer coating solution>
The following additives were sequentially mixed to prepare an image forming layer coating solution. After the preparation, the coating solution was degassed under reduced pressure (pressure 55 kPa) for 45 minutes. The coating solution had a pH of 7.5 and a viscosity of 45 mPa · s at 25 ° C.

Fatty acid silver dispersion 72g
Binder: Exemplary latex polymer P-1 (chloride ion concentration: 9 ppm) 41 g
Reducing agent A dispersion 17.3 g
6.5 g of solid fine particle dispersion of organic polyhalogen compound A
2.2g of solid fine particle dispersion of organic polyhalogen compound B
Salicylic acid derivative dispersion A 4.2 g
Sodium ethylthiosulfonate (1% by weight aqueous solution) 1.4 g
Benzotriazole (5% by weight aqueous solution) 1.2 g
Polyvinyl alcohol (Kuraray Co., Ltd., PVA-235, 5% by mass aqueous solution)
9.9g
Dispersion of 6-isopropylphthalazine compound 12.7 g
Silver halide emulsion A 18.6g
6.8 g of solid fine particle dispersion of super-hardening agent H
Preservative: Compound A (40 ppm in the coating solution) 2.5 mg / m ²
In the image forming layer coating solution, the chloride ion concentration contained in latex polymer P-1 with respect to fatty acid silver is 150 ppm.

(Preparation of protective layer coating solution)
Methyl methacrylate / styrene / 2-ethylhexyl acrylate / 2-hydroxyethyl methacrylate / acrylic acid = 58.9 / 8.6 / 25.4 / 5.1 / 2 (mass%) polymer latex solution (copolymer and glass Transition temperature 46 ° C. (calculated value) 21.5% by mass as a solid content concentration, 100 ppm of compound A, and further 15% by mass of compound B as a film-forming aid with respect to the solid content of the latex. Water was added to 943 g having a transition temperature of 24 ° C. and an average particle diameter of 116 nm), to which 1.62 g of compound C, 0.69 g of sodium dihydrogen orthophosphate dihydrate as a solid content, development accelerator 11.55 g of W as solid content, 1.58 g of matting agent (polystyrene particles, average particle size 7 μm, coefficient of variation of average particle size 8%) And polyvinyl alcohol (Kuraray Co., Ltd., PVA-235) was added 29.3 g, was prepared further protective layer coating solution by the addition of water (a methanol solvent containing 0.8% by mass of). After preparation, vacuum degassing (pressure 47 kPa) was performed for 60 minutes. The coating solution had a pH of 5.5 and a viscosity of 45 mPa · s at 25 ° C.

(Preparation of overcoat first layer coating solution)
Methyl methacrylate / styrene / 2-ethylhexyl acrylate / 2-hydroxyethyl methacrylate / acrylic acid = 58.9 / 8.6 / 25.4 / 5.1 / 2 (mass%) polymer latex solution (copolymer and glass A transition temperature of 46 ° C. (calculated value), a solid content concentration of 21.5% by mass, 100 ppm of compound A, and further 15% by mass of compound B as a film-forming aid with respect to the solid content of the latex Water was added to 625 g of an average particle diameter of 74 nm with a glass transition temperature of 24 ° C., to which 11.7 g of compound D, 2.7 g of compound F, and polyvinyl alcohol (PVA-235, manufactured by Kuraray Co., Ltd.). Was added, and water was further added to prepare an overcoat first layer coating solution (containing 0.1% by mass of methanol solvent). After preparation, vacuum degassing (pressure 47 kPa) was performed for 60 minutes. The coating solution had a pH of 2.6 and a viscosity of 30 mPa · s at 25 ° C.

(Preparation of overcoat second layer coating solution)
Methyl methacrylate / styrene / 2-ethylhexyl acrylate / 2-hydroxyethyl methacrylate / acrylic acid = 58.9 / 8.6 / 25.4 / 5.1 / 2 (mass%) polymer latex solution (copolymer and glass A transition temperature of 46 ° C. (calculated value), a solid content concentration of 21.5% by mass, 100 ppm of compound A, and further 15% by mass of compound B as a film-forming aid with respect to the solid content of the latex Water was added to 649 g of an average particle diameter of 116 nm with a glass transition temperature of 24 ° C., and a 30% by mass solution of carnauba wax (manufactured by Chukyo Yushi Co., Ltd., Cerozol 524: less than 5 ppm as silicone content) was added. 4 g, 1.85 g of compound C, 1.0 g of compound E, matting agent (polystyrene particles, average particle size 7 μm, average particle 3.45 g of size variation coefficient and 26.5 g of polyvinyl alcohol (manufactured by Kuraray Co., Ltd., PVA-235) were added, and water was further added to add the overcoat second layer coating solution (methanol solvent to 1.1%). (Mass% content) was prepared. After preparation, vacuum degassing (pressure 47 kPa) was performed for 60 minutes. The coating solution had a pH of 5.3 and a viscosity of 25 mPa · s at 25 ° C.

(Application)
Using the support 1 provided with the back layer, on the surface opposite to the back layer, using the slide beat coating method disclosed in FIG. 1 of the specification of JP-A-2000-2964, The above image forming layer coating solution is applied in an amount of 1.5 g / m ² as a coating silver amount, and further, the protective layer coating solution is applied simultaneously in a multilayer so that the solid content coating amount of the polymer latex is 1.29 g / m ^2. did. Thereafter, the overcoat first layer coating solution on the protective layer has a polymer latex solids coating amount of 1.97 g / m ² , and the overcoat second layer coating solution has a polymer latex solids coating amount of 1.97 g / m ² . The heat-developable image recording material 1 was produced by simultaneously applying multiple layers so as to be 07 g / m ² and drying.

<< Preparation of heat-developable image recording materials 2-11 >>
In the production of the heat-developable image recording material 1, the exemplary latex polymer P-1 (chloride ion concentration: 9 ppm) used for the preparation of the image forming layer coating solution was changed to each latex polymer shown in Table 2, Heat-developable image recording materials 2 to 11 were produced in the same manner except that the addition amount was appropriately adjusted so that the chloride ion concentration relative to the organic silver salt (fatty acid silver dispersion) as described in 2 was obtained.

<< Preparation of heat-developable image recording material 12 >>
In the production of the heat-developable image recording material 1, except that a spectral sensitizing dye (Exemplary Compound (I-32)) was used instead of the spectral sensitizing dye (Exemplary Compound (I-6)), A heat-developable image recording material 12 was produced.

<< Preparation of heat-developable image recording material 13 >>
In the production of the heat-developable image recording material 1, a heat-developable image recording material 13 was produced in the same manner except that the sensitizing dye 1 was used instead of the spectral sensitizing dye (Exemplary Compound (I-6)). .

<Evaluation of heat-developable image recording material>
[Cutting the sample]
Each of the heat-developable image recording materials prepared above was cut into four sizes, packaged and sealed in the following packaging materials in an environment of 25 ° C. and 50% RH, and stored at 23 ° C. for 2 weeks. A reference sample was used.

<Packaging materials>
Polyethylene terephthalate film: 10 μm / polyethylene film: 12 μm / aluminum foil: 9 μm / nylon sheet: 15 μm / packaging material consisting of 50 μm polyethylene film containing 3% by mass of carbon, oxygen permeability is 0 ml / atm · m ² · 25 ° C. Day, moisture permeability: 0 g / atm · m ² · 25 ° C. · day.

[Evaluation of preservability]
Each reference sample was subjected to a forced deterioration treatment for 2 months in an environment of 30 ° C. to obtain a forced deterioration sample. The following evaluation was performed on the prepared reference sample and forced deterioration sample.

<Exposure and heat development processing>
Each sample was exposed to xenon flash light having a light emission time of 10 ⁻⁶ seconds through a step wedge through an interference filter having a peak at 410 nm, and then subjected to heat development at 117 ° C. for 20 seconds.

<Creation of characteristic curve>
For the heat-developed sample, the formed silver image is subjected to density measurement with a Macbeth TD904 densitometer (visible density), and a characteristic curve consisting of a vertical axis: density (D) and a horizontal axis: logarithm of exposure (Log E) Created.

<Measurement of sensitivity>
The reciprocal of the exposure amount (Log E) required to obtain a density of 1.0 for each sample was defined as sensitivity, and the relative sensitivity was determined with the sensitivity of the reference sample of the heat-developable image forming material as 100.

<Measurement of fog density>
The fog density of the forcedly deteriorated sample and the reference sample of each sample was measured.

<Evaluation of image contrast>
In the characteristic curve of each sample, the density point of fog density +0.5 and the density point of fog density +1.5 were connected by a straight line, and the slope (tan θ) of the curve was obtained as a gamma value.

  The results obtained as described above are shown in Table 2.

  As is apparent from Table 2, the heat-developable image recording material of the present invention having a chloride ion content of 1000 ppm or less with respect to the non-photosensitive organic silver salt was obtained by image exposure with light having a wavelength of 500 nm or less. As compared with the comparative example, it can be seen that even when the image is stored at a high temperature for a long period of time, the impression fluctuation and the fog density increase are small, and the gradation fluctuation (contrast) is reduced.

Claims (2)

An image forming layer containing at least a non-photosensitive organic silver salt, a reducing agent for the organic silver salt, a photosensitive silver halide, a super-high contrast agent, and an organic binder is provided on the support, and an image is formed with light having a wavelength of 500 nm or less. In the heat-developable image recording material to be exposed, the chloride ion concentration in the non-photosensitive organic silver salt-containing layer is 1000 ppm or less with respect to the non-photosensitive organic silver salt. The heat-developable image recording material according to claim 1, comprising a spectral sensitizing dye represented by the following general formula (1) or (2).

[Wherein, Z ¹ and Z ² are each independently unsubstituted or substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a phenyl group, or thiazoline. To form a ring, thiazole ring, benzothiazole ring, naphthothiazole ring, selenazole ring, benzoselenazole ring, naphthselenazole ring, oxazole ring, benzoxazole ring, naphthoxazole ring, imidazole ring, benzimidazole ring or pyridine ring Represents a necessary nonmetallic atom group, R ¹¹ and R ¹² each represent an alkyl group having 1 to 4 carbon atoms, a hydroxyalkyl group, a carboxyalkyl group or a sulfoalkyl group; n1 and n2 each represents 0 or 1; X ⁻ represents an anion, and m1 represents 1 or 2. ]

[In the formula, Z ³ is unsubstituted or substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a phenyl group, benzoxazole ring, thiazole ring, benzo Z ⁴ represents a nonmetallic atom group necessary for forming a thiazole ring, a selenazole ring, a benzoselenazole ring or a pyridine ring, and Z ⁴ represents a 2-thiohydratoin ring, a 2-thiooxazolidine-2,4′-dione ring or a rhodanine ring. Represents a group of nonmetallic atoms necessary for formation, R ¹⁴ represents an alkyl group having 1 to 4 carbon atoms, a carboxyalkyl group, or a hydrogen atom, R ¹⁵ represents an alkyl group having 1 to 4 carbon atoms or a hydrogen atom, n3 represents 0 or 1. ]