JP2006189692A - Heat developable photosensitive material and image forming method using the heat developable photosensitive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat developable photosensitive material having ultrahigh contrast and low fogging as a material for a scanner or an image setter for printing plate making, being stable to the change of developing temperature, and free of occurrence of image defects in such steps as printing and automatic transport of a PS plate, and to provide an image forming method with which the heat developable photosensitive material is processed with an automatic heat developing machine. <P>SOLUTION: The heat developable photosensitive material has on a support an image forming layer comprising a non-photosensitive organic silver salt, a reducing agent, a photosensitive silver halide, a contrast enhancer and a binder and a non-photosensitive layer for protecting the image forming layer, wherein the contrast enhancer is a compound represented by formula (1) and adhesive strength between the image forming layer and the non-photosensitive layer after heat development is ≥90 N/m. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photothermographic material and an image forming method using the photothermographic material, and more particularly to a photothermographic material suitable for printing plate making and an image forming method using the photothermographic material.

  In recent years, in the field of photoengraving, reduction of waste processing liquid has been strongly desired from the viewpoint of environmental protection and space saving. Therefore, photothermographic materials for photoengraving that can be efficiently exposed by a laser scanner or a laser imagesetter and can form a clear black image having high resolution and sharpness have attracted attention. Development is needed. According to such a photothermographic material, it is possible to supply a customer with a photothermographic processing system that does not require solution processing chemicals and that is simpler and does not impair the environment.

  Methods for forming an image by thermal development are known, for example, in Patent Documents 1 and 2 and Non-Patent Document 1. Such a photothermographic material usually contains a non-photosensitive silver source (for example, an organic silver salt) that can be reduced and a catalytically active photocatalyst (for example, a halogenated salt) in a photosensitive layer (image forming layer) on a support. Silver) and a silver reducing agent are usually contained in a state dispersed in an organic binder matrix. This photosensitive material is stable at room temperature, but when heated to a high temperature (for example, 80 ° C. or higher) after exposure, silver is converted through a redox reaction between a reducible silver source (which functions as an oxidizing agent) and a reducing agent. Generate. This redox reaction is promoted by the catalytic action of the latent image formed by exposure. The silver produced by the reaction of the reducible silver salt in the exposed area turns black and forms an image because it contrasts with the unexposed area.

  As a method for obtaining a photothermographic material having a high Dmax and a high contrast, a hydrazine derivative is used (see Patent Document 3), an acrylonitrile is used as a co-developer (see Patent Document 4), and the like. A photothermographic material containing a ballast group-containing alkene compound, a substituted alkene compound, and a specific heterocyclic compound as an agent is disclosed (see Patent Documents 5, 6, and 7).

  However, these photothermographic materials have a problem that sensitivity, maximum density, and line width largely vary due to variations in humidity in the development environment, and improvements have been desired.

  In printing plate making applications, after output by a scanner or an image setter, a film on which an image is formed by heat development is printed as a manuscript on a PS plate or the like. At that time, if the number of times of printing is repeated, image defects are often generated on the original film, or in an automatic conveyance system, it is often fixed and conveyed with an adhesive tape and peeled off from the adhesive tape again. Problems such as the occurrence of film breakage on the surface having the image forming layer of the film have often become a problem.

Therefore, there has been a demand for a photothermographic material capable of obtaining a high contrast and high maximum density performance and causing no image defects during handling in a process such as an automatic conveyance system.
US Pat. No. 3,152,904 US Patent 3,457,075 US Pat. No. 5,496,695 US Pat. No. 5,545,515 JP-A-11-109546 JP 11-119372 A Japanese Patent Laid-Open No. 11-231459 JP 7-13294 A D. Klosterbor, “Thermally Processed Silver Systems,” Imaging Processes and Materials, 8th Edition, J. Am. Sturge, V.C. Wallworth, A.M. Edited by Shepp, Chapter 9, page 279, 1989

  The present invention has been made in view of the above circumstances, and the object of the present invention is as a scanner for printing plate making and an image setter, with super-high contrast, low fog, and stable against fluctuations in development temperature, In addition, there is provided a photothermographic material (hereinafter also referred to as photosensitive material) free from image defects in processes such as printing of PS plates and automatic conveyance systems, and an image forming method for processing the photothermographic material with a photothermographic developing machine. It is to provide.

  The above object of the present invention is achieved by the following configurations.

(Claim 1)
A photothermographic material having an image forming layer containing a non-photosensitive organic silver salt, a reducing agent, a photosensitive silver halide, a high contrast agent and a binder and a non-photosensitive layer protecting the image forming layer on a support. In the above, the contrast enhancing agent is a compound represented by the following general formula (1), and the adhesive strength between the image forming layer and the non-photosensitive layer after heat development is 90 N / m or more. Photothermographic material.

[Wherein, R ₁ represents an alkyl group, an aryl group or a heterocyclic group, R ₂ represents an alkoxy group, an aryloxy group or an alkylamino group, and M represents a cation other than a hydrogen cation. ]
(Claim 2)
The photothermographic material according to claim 1, wherein the photothermographic material is processed by an automatic heat developing machine having a preheating portion in front of the heat developing portion and having a temperature of 80 to 120 ° C. Method.

  According to the present invention, there is provided a photothermographic material having super high contrast, low fog, low humidity dependency during development processing, and further free from image defects in handling in processes such as printing and automatic conveyance systems such as PS plates. The image forming method can be provided.

  Hereinafter, the present invention will be described in more detail.

  The photothermographic material of the invention contains a compound represented by the general formula (1). First, the compound of general formula (1) will be described in detail.

In general formula (1), the alkyl group represented by R ₁ includes a linear or branched, cyclic, or a combination thereof, which is a substituted or unsubstituted alkyl group. That is, an alkyl group (preferably having 1 to 30 carbon atoms in total, such as methyl, ethyl, propyl, i-propyl, t-butyl, octyl, eicosyl, 2-chloroethyl, 2-cyanoethyl, 2-ethylhexyl), cycloalkyl group (Preferably a substituted or unsubstituted cyclohexyl, cyclopentyl, 4-dodecylcyclohexyl, etc. having 3 to 30 carbon atoms), a bicycloalkyl group (preferably a substituted or unsubstituted bicycloalkyl group having 5 to 30 carbon atoms, that is, Bicyclo [1.2.2] heptan-2-yl and bicyclo [2.2.2] octane-3, which are monovalent groups obtained by removing one hydrogen atom from a bicycloalkane having 5 to 30 carbon atoms in total. -Yl, etc.), and tricyclo structures having more ring structures. An alkyl group (for example, an alkyl group of an alkylthio group) in the substituents described below also represents such an alkyl group.

The aryl group represented by R ₁ is preferably a substituted or unsubstituted aryl group having 6 to 50 carbon atoms, such as phenyl, p-tolyl, naphthyl, m-chlorophenyl, o-hexadecanoylaminophenyl, etc. The heterocyclic group represented by R ₁ is preferably a 5- or 6-membered substituted or unsubstituted aromatic or non-aromatic heterocyclic compound residue, more preferably total carbon. It is a 5- or 6-membered aromatic ring group having a number of 3 to 50. Examples include 2-furyl, 2-thienyl, 2-pyrimidinyl, 2-benzothiazolyl and the like. R ₁ is preferably an aryl group.

  Examples of the substituent for the alkyl group, aryl group, and heterocyclic group include an alkyl group (including a cycloalkyl group and a bicycloalkyl group), an alkenyl group (including a cycloalkenyl group and a bicycloalkenyl group), an alkynyl group, and an aryl group. , Heterocyclic group, cyano group, hydroxyl group, nitro group, carboxyl group, alkoxy group, aryloxy group, silyloxy group, heterocyclic oxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy, amino Groups (including anilino groups), acylamino groups, aminocarbonylamino groups, alkoxycarbonylamino groups, aryloxycarbonylamino groups, sulfamoylamino groups, alkyl and arylsulfonamido groups, mercapto groups, alkylthio groups, ant Ruthio group, heterocyclic thio group, sulfamoyl group, sulfo group, alkyl and arylsulfinyl group, alkyl and arylsulfonyl group, acyl group, aryloxycarbonyl group, alkoxycarbonyl group, carbamoyl group, aryl and heterocyclic azo group, imide group Phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, silyl group and the like.

  The most preferred substituent is an acylamino group having 8 to 50 carbon atoms in total, an aminocarbonylamino group, or an alkoxycarbonylamino group.

In the general formula (1), R ₂ is an alkoxy group (preferably a substituted or unsubstituted alkoxy group having 1 to 30 carbon atoms, more preferably 1 to 20, particularly preferably 1 to 10 carbon atoms, methoxy, ethoxy, propoxy I-propoxy, t-butoxy, octyloxy, 2-methoxyethoxy, etc.), an aryloxy group (preferably having a total carbon number of 6 to 30, more preferably 6 to 20, particularly preferably 6 to 10) An aryloxy group such as phenoxy, 4-methylphenoxy, 4-t-butylphenoxy, 4-methoxyphenoxy, 4-dimethylaminophenoxy, etc., an unsubstituted amino group or an alkylamino group (preferably having a total carbon number of 1 to 30, more preferably 1-20, particularly preferably 1-10 substituted or unsubstituted alkylamino groups Including those of cyclic represents methylamino, ethylamino, dimethylamino, diethylamino, pyrrolidino, morpholino, 2-hydroxyethylamino, 2-methoxy-ethylamino, bis (2-methoxyethyl) amino, etc.). R ₂ is preferably an alkoxy group or an alkylamino group.

As the substituent for the alkoxy group, aryloxy group and alkylamino, the same groups as those described above for the substituent for the alkyl group, aryl group and heterocyclic group for R ₁ can be used.

  M represents a cation other than a hydrogen ion, that is, a counter cation of an oxygen anion, which may be a metal ion or a non-metal ion. Examples of cations other than hydrogen ions include sodium, potassium, magnesium, calcium, zinc, silver, quaternary ammonium (tetrabutylammonium, benzyltrimethylammonium, etc.) and the like. M is preferably sodium, potassium, zinc or quaternary ammonium.

  Although the specific example of a compound represented by General formula (1) below is shown, this invention is not limited to these.

  These compounds can be easily obtained by synthesizing a 5-pyrazolone compound by a known method, formylating with a Vilsmeier reagent or the like, and then treating under alkaline conditions. A typical synthesis example is shown below.

(Synthesis of Compound Example A-4)
120 g of p-nitrophenylhydrazine and 200 g of ethyl 3-amino-3-ethoxyacrylate hydrochloride were dissolved in 650 ml of dimethylacetamide and stirred at room temperature for 30 minutes. 450 g of a 28% methanol solution of sodium methoxide was added to the reaction solution, and the mixture was further stirred at room temperature for 30 minutes. 200 ml of concentrated hydrochloric acid and 400 ml of water were added to the reaction solution, and the precipitated crystals were filtered and washed with water. 150 g of intermediate (A) was obtained. A mixture of 100 g of intermediate (A), 160 g of reduced iron, 800 ml of i-propyl alcohol, 80 ml of water and 2 g of ammonium chloride was refluxed with heating for 2 hours. The insoluble material was filtered through Celite while hot, 50 ml of concentrated hydrochloric acid was added to the filtrate, and the solvent was distilled off under reduced pressure. Ethanol was added to the residue, and the precipitated crystals were filtered to obtain 70 g of intermediate (B).

  26 g of intermediate (B) and 20 g of pyridine were dissolved in 120 ml of dimethylacetamide, and 27 g of i-palmitic acid chloride was slowly added dropwise while cooling with ice. After stirring for 30 minutes, 150 ml of diluted hydrochloric acid was added, and the precipitated crystals were filtered. Recrystallization from acetonitrile gave 35 g of intermediate (C). Intermediate (C) 35 g was dissolved in DMF (dimethylformamide) 170 ml, and dimethylformamide dimethylacetal 11 ml was added at room temperature. The precipitated crystals were filtered. 25 g of intermediate (D) was obtained. After 16 g of intermediate (D), 90 ml of methanol and 7.5 ml of 5 mol / L sodium hydroxide solution were stirred at 50 ° C. for 30 minutes, 50 ml of 20% saline was added. The precipitated crystals were filtered and washed thoroughly with water. 14 g of Compound Example A-4 was obtained.

  The compound of the general formula (1) is water or an appropriate organic solvent such as alcohols (methanol, ethanol, propanol, fluorinated alcohol, etc.), ketones (acetone, methyl ethyl ketone, etc.), dimethylformamide, dimethyl sulfoxide, methyl cellosolve, etc. It can be dissolved in In addition, it is dissolved by using a well-known emulsification dispersion method using an oil such as dibutyl phthalate, tricresyl phosphate, glyceryl triacetate or diethyl phthalate, or an auxiliary solvent such as ethyl acetate or cyclohexanone, and mechanically emulsified dispersion. Can be used. Furthermore, the powder can be dispersed in water by a method known as a solid dispersion method, using a ball mill, a colloid mill, a sand grinder mill, a manton gourin, a microfluidizer or ultrasonic waves.

  The compound of the general formula (1) may be added to any layer on the image forming layer side with respect to the support, but is preferably added to a layer containing a silver salt or an adjacent layer thereof.

The addition amount of the compound of the general formula (1) depends on the kind of the photographically useful group, but is preferably 1 × 10 ⁻⁶ to 1 mol per 1 mol of silver, and more preferably 1 × 10 ^{−5 to} 5 × 10 ⁻¹ mol. 2 × 10 ⁻⁵ to 2 × 10 ⁻¹ mol is most preferable. Only 1 type may be used for a compound and it may use 2 or more types together.

  The photothermographic material of the invention is characterized in that the adhesive strength between the image forming layer and the protective layer after heat development is 90 N / m or more. The adhesive strength between the image forming layer and the protective layer is defined as the image forming layer and the protective layer after the photothermographic material is thermally developed and left in an environment of 25 ° C. and 55% RH (relative humidity) for 2 hours. It means the adhesive strength between the layers. This adhesive strength can be determined by a T-shaped peel test method described in JIS K 6854 “Test method for peel strength of adhesive”.

  In the present invention, the adhesive strength between the image forming layer and the protective layer after heat development is 90 N / m or more, preferably 100 N / m or more.

  As a method of achieving the adhesive strength between the layers of the present invention, it is preferable to add an organic solvent having an evaporation index of 500 or less to the protective layer coating solution. The addition amount of this organic solvent is 1-30 mass% with respect to the solvent amount in a protective layer coating liquid, Preferably it is 5-15 mass%.

  The evaporation index of an organic solvent represents the evaporation property by the ratio of the evaporation rate to butyl acetate (with an evaporation rate of 100). Assuming that the evaporation rate index of the solvent as seen on such a scale is E, the relationship between E and the vapor pressure of the solvent: p (pressure expressed in kPa) and the molecular weight: M is expressed by the following formula (a). .

Formula (a) E = 7.50 kpM
Here, k varies depending on the temperature at the time of measurement, and the values of k for vapor pressures of 20 ° C. and 30 ° C. are given by equations (b) and (c), respectively.

Formula (b) E = 0.82 pM (p is measured at 20 ° C.)
Formula (c) E = 0.41 pM (p is measured at 30 ° C.)
When E exceeds 300, the evaporation rate is classified as “fast”, 130-300 is “medium”, 40-130 is “slow”, and less than 40 is classified as “very slow” (by TEMPLE C. PATTON: Ueki Published by Kyoritsu Publishing Co., Ltd., translated by Kenji.

  Specific examples of compounds having an evaporation index of 500 or less include ethanol (340), propanol (110), i-propanol (300), diethyl ketone (275), methyl-i-butyl ketone (165), butyl acetate (100). , Toluene (240) and the like. Figures in parentheses indicate the evaporation index.

  The photothermographic material of the present invention contains an organic silver salt as a reducible silver salt. This organic silver salt is relatively stable to light, but when heated to 80 ° C. or higher in the presence of an exposed photocatalyst (such as a latent image of photosensitive silver halide) and a reducing agent A silver salt that forms a silver image. The organic silver salt may be any organic material that contains a reducible source of silver ions. Silver salts of organic acids, particularly silver salts of long chain fatty carboxylic acids having 10 to 30 carbon atoms, preferably 15 to 28 carbon atoms are preferred. Also preferred are organic or inorganic silver salt complexes where the ligand has a complex stability constant in the range of 4.0 to 10.0. Preferable organic silver salts include silver salts of organic compounds having a carboxyl group. Specific examples include a silver salt of an aliphatic carboxylic acid and a silver salt of an aromatic carboxylic acid, but are not limited thereto. Preferred examples of the aliphatic carboxylic acid silver salt include silver behenate, silver arachidate, silver stearate, silver oleate, silver laurate, silver caproate, silver myristate, silver palmitate, silver maleate and fumarate. Examples thereof include silver oxide, silver tartrate, silver linoleate, silver butyrate and silver camphorate, and mixtures thereof. This silver-feeding material can preferably constitute about 5 to 70% by weight of the image-forming layer.

  In the present invention, among the above organic acid silver or a mixture of organic acid silver, it is preferable to use an organic acid silver having a silver behenate content of 75 mol% or more, and a silver behenate content of 85 mol% (molar fraction). It is more preferable to use the above organic acid silver. As the organic acid silver other than silver behenate contained in the organic acid silver used in the present invention, those described above can be preferably used.

  The organic acid silver of the present invention is prepared by reacting a solution or suspension of an alkali metal salt (sodium salt, potassium salt, lithium salt, etc.) of the above organic acid with silver nitrate. As for these preparation methods, the method described in paragraph Nos. “0019 to 0021” of JP-A No. 2000-292882 can be used. In the present invention, a method of preparing organic acid silver by adding an aqueous silver nitrate solution and an organic acid alkali metal salt solution into a means for mixing a sealed liquid can be preferably used. Specifically, the method described in JP-A-2001-33907 can be used. In the present invention, a water-soluble dispersant can be added to the silver nitrate aqueous solution and the organic acid alkali metal salt solution or the reaction solution when preparing the organic acid silver. About the kind and usage-amount of a dispersing agent used here, it describes in Unexamined-Japanese-Patent No. 2000-305214 paragraph number "0052".

  The organic acid silver is preferably prepared in the presence of a tertiary alcohol. The tertiary alcohol is preferably a compound having a total carbon number of 15 or less, and particularly preferably a compound having 10 or less. Examples of preferred tertiary alcohols include t-butanol, but the tertiary alcohol that can be used is not limited thereto. The addition timing of the tertiary alcohol may be any timing at the time of preparing the organic acid silver, but it is preferably added at the time of preparing the organic acid alkali metal salt to dissolve and use the organic acid alkali metal salt. Further, the tertiary alcohol used in the present invention can be used in a mass ratio of 0.01 to 10 with respect to water as a solvent at the time of preparing the organic acid silver, but in a range of 0.03 to 1. It is preferable to use it.

  The shape and size of the organic silver salt that can be used in the present invention are not particularly limited, but those described in paragraph number “0024” of JP-A No. 2000-292882 are preferably used. The shape of the organic silver salt can be determined from a transmission electron microscope image of the organic silver salt dispersion. As another method for measuring monodispersity, there is a method for obtaining the standard deviation of the volume weighted average diameter of the organic silver salt, and the percentage (coefficient of variation) of the value divided by the volume weighted average diameter is preferably 80% or less. Preferably it is 50% or less, More preferably, it is 30% or less. As a measurement method, for example, the organic silver salt dispersed in the liquid is irradiated with laser light, and the particle size (volume weighted average diameter) obtained by calculating the autocorrelation function with respect to the temporal change of the fluctuation of the scattered light is obtained. be able to. The average particle size in this measurement method is preferably a solid fine particle dispersion of 0.05 to 10.0 μm. A more preferable average particle size is 0.1 to 5.0 μm, and a further preferable average particle size is 0.1 to 2.0 μm.

  The organic silver salt is preferably desalted. The desalting method is not particularly limited, and a known method can be used, but a known filtration method such as centrifugal filtration, suction filtration, ultrafiltration, and flock-forming water washing by an agglomeration method can be preferably used. As the ultrafiltration method, the method described in JP-A No. 2000-305214 can be used. In the present invention, for the purpose of obtaining an organic silver salt solid dispersion having a high S / N, a small particle size, and no aggregation, the organic silver salt as an image forming medium is contained, and the photosensitive silver salt is substantially contained. It is preferable to use a dispersion method in which a pressure drop is performed after converting a non-aqueous dispersion into a high-speed flow. As for these dispersion methods, the methods described in paragraph Nos. “0027 to 0038” of JP-A No. 2000-292882 can be used. The particle size distribution of the organic silver salt solid fine particle dispersion is preferably monodispersed. Specifically, the percentage (variation coefficient) of the value obtained by dividing the standard deviation of the volume load average diameter by the volume load average diameter is 80% or less, more preferably 50% or less, and still more preferably 30% or less.

The organic silver salt solid fine particle dispersion is composed of at least an organic silver salt and water. The ratio of the organic silver salt and water is not particularly limited, but the ratio of the organic silver salt to the whole is preferably 5 to 50% by mass, and particularly preferably 10 to 30% by mass. It is preferable to use the above-mentioned dispersion aid, but it is preferable to use the minimum amount in a range suitable for minimizing the particle size, and 0.5 to 30% by weight, particularly 1 to 15%, based on the organic silver salt. A range of mass% is preferred. The organic silver salt in the present invention can be used in a desired amount, preferably 0.1-5 g / m ² as silver amount, more preferably from 1 to 3 g / m ^2.

In the present invention, it is preferable to add a metal ion selected from Ca, Mg, Zn and Ag to the non-photosensitive organic silver salt. Regarding the addition of a metal ion selected from Ca, Mg, Zn and Ag to the non-photosensitive organic silver salt, it is preferable to add it in the form of a water-soluble metal salt which is not a halide, specifically nitrate or sulfuric acid. It is preferable to add in the form of a salt or the like. Addition with a halide is not preferable because it deteriorates image storability by so-called light (indoor light, sunlight, etc.) of the processed photosensitive material, so-called printout property. For this reason, in this invention, it is preferable to add in the form of the water-soluble metal salt which is not a halide. The metal ion selected from Ca, Mg, Zn and Ag is added after the formation of the non-photosensitive organic silver salt particles, immediately after the formation of the particles, before the dispersion, immediately after the dispersion, and before and after the coating solution preparation. Any period may be used as long as it is up to, and preferably after the dispersion and before and after the preparation of the coating solution. The addition amount of a metal ion selected from Ca, Mg, Zn and Ag is preferably 10 ⁻³ to 10 ⁻¹ mol per mol of non-photosensitive organic silver, and particularly 5 × 10 ^{−3 to} 5 × 10 ⁻² mol. Is preferred.

  The photothermographic material of the present invention contains photosensitive silver halide. The halogen composition of the photosensitive silver halide used is not particularly limited, and silver chloride, silver chlorobromide, silver bromide, silver iodobromide, and silver chloroiodobromide can be used. Grain formation of the photosensitive silver halide emulsion can be carried out by the method described in paragraph No. 0217-0224 of JP-A No. 11-119374, but is not particularly limited to this method. . Examples of the shape of the silver halide grains include cubes, octahedrons, tetradecahedrons, tabular shapes, spherical shapes, rod shapes, potato shapes, and the like. In the present invention, cubic grains or tabular grains are particularly preferred. 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 JP-A-11-119374, paragraph number “0225”. Further, the distribution of the halogen composition may be uniform inside and on the surface of the silver halide grains, the halogen composition may be changed stepwise, or may be changed continuously. Further, silver halide grains having a core / shell structure can be preferably used. As the structure, core / shell particles having a preferably 2- to 5-fold structure, more preferably a 2- to 4-fold structure can be used. A technique for localizing silver bromide on the surface of silver chloride or silver chlorobromide grains can also be preferably used.

The particle size distribution of the silver halide grains used has a monodispersity value of 30% or less, preferably 1 to 20%, and further 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 diameter by the average particle diameter. For the sake of convenience, the grain size of silver halide grains is represented by the edge length in the case of cubic grains, and the other grains (octahedron, tetrahedron, flat plate, etc.) are calculated by the projected area circle equivalent diameter. The photosensitive silver halide grains used in the present invention contain a Group VII or Group VIII metal or metal complex of the Periodic Table. As the central metal of the Group VII or Group VIII metal or metal complex of the periodic table, rhodium, rhenium, ruthenium, osnium and iridium are preferable. Particularly preferred metal complexes are (NH ₄ ) ₃ Rh (H ₂ O) Cl ₅ , K ₂ Ru (NO) Cl ₅ , K ₃ IrCl ₆ , K ₄ Fe (CN) ₆ . 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 content is preferably in the range of 1 × 10 ⁻⁹ mol to 1 × 10 ⁻³ mol, more preferably in the range of 1 × 10 ⁻⁸ mol to 1 × 10 ⁻⁴ mol, with respect to 1 mol of silver. As a specific metal complex structure, a metal complex having a structure described in JP-A-7-225449 can be used. The types and addition methods of these heavy metals are described in paragraph Nos. “0227 to 0240” of JP-A No. 11-119374.

  The photosensitive silver halide grains can be desalted by a water washing method known in the art, such as a noodle method or a flocculation method, but may or may not be desalted in the present invention. The photosensitive silver halide emulsion used in the present invention is preferably chemically sensitized. For chemical sensitization, the method described in paragraph Nos. “0242 to 0250” of JP-A No. 11-119374 is preferably used. Further, a thiosulfonic acid compound may be added to the silver halide emulsion by the method shown in European Patent Publication No. 293,917.

  As the binder contained in the photosensitive silver halide of the present invention, gelatin is preferred. As the gelatin, low molecular weight gelatin is preferably used in order to maintain a good dispersion state of the photosensitive silver halide emulsion in the organic silver salt-containing coating solution. The molecular weight (weight average molecular weight) of the low molecular weight gelatin is 500 to 60,000, preferably 1,000 to 40,000. These low molecular weight gelatins may be used at the time of particle formation or dispersion after desalting, but are preferably used at the time of dispersion after desalting. Ordinary gelatin (molecular weight of about 100,000) may be used for grain formation, and low molecular weight gelatin may be used for dispersion after desalting. The binder concentration can be 0.05 to 20% by mass, but a concentration range of 5 to 15% by mass is preferable for handling. As the type of gelatin, alkali-treated gelatin is usually used, but modified gelatin such as acid-treated gelatin and phthalated gelatin can also be used.

  Only one silver halide emulsion may be used in the light-sensitive material, or two or more (for example, those having different average grain sizes, different halogen compositions, different crystal habits, and different chemical sensitization conditions) May be used in combination. The amount of the photosensitive silver halide used is preferably 0.01 to 0.5 mol, more preferably 0.02 to 0.3 mol, and 0.03 to 0.25 mol with respect to 1 mol of the organic silver salt. Is particularly preferred. Regarding the mixing method and mixing conditions of the photosensitive silver halide and the organic silver salt prepared separately, the silver halide particles and the organic silver salt that have been prepared are respectively mixed with a high-speed stirrer, ball mill, sand mill, colloid mill, vibration mill, There are a method of mixing with a homogenizer or the like, or a method of preparing an organic silver salt by mixing photosensitive silver halide that has been prepared at any timing during the preparation of the organic silver salt. There is no particular limitation as long as it is sufficiently obtained. In addition, mixing two or more organic silver salt aqueous dispersions and two or more photosensitive silver salt aqueous dispersions is a preferable method for adjusting photographic characteristics.

  In the present invention, a high contrast accelerator can be used in combination for forming a super high contrast image. 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, specifically HA-1 to HA— 11, acrylonitriles described in No. 5,545,507, specifically CN-1 to CN-13, hydrazine compounds described in No. 5,558,983, specifically CA-1 to CA- 6, Onium 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.

  In a photothermographic material having a non-photosensitive organic silver salt, a photosensitive silver halide and a binder, formic acid or formate is a strong fogging substance. Therefore, in the present invention, the content of formic acid or formate on the side having an image forming layer containing photosensitive silver halide is preferably 5 mmol or less, more preferably 1 mmol or less per mol of silver.

In the photothermographic material of the present invention, it is preferable to use an acid formed by hydration of diphosphorus pentoxide or a salt thereof in combination with a superhigh contrast agent. Acids or salts thereof formed by hydration of diphosphorus pentoxide include metaphosphoric acid (salt), pyrophosphoric acid (salt), orthophosphoric acid (salt), triphosphoric acid (salt), tetraphosphoric acid (salt), hexametaphosphoric acid ( Salt). Particularly preferable examples of the acid or salt thereof formed by hydrating diphosphorus pentoxide include orthophosphoric acid (salt) and hexametaphosphoric acid (salt). Specific examples of the salt include sodium orthophosphate, sodium dihydrogen orthophosphate, sodium hexametaphosphate, and ammonium hexametaphosphate. The acid or salt thereof formed by hydrating diphosphorus pentoxide, which can be preferably used in the present invention, is added to the image forming layer or a protective layer adjacent thereto from the viewpoint that a desired effect is exhibited in a small amount. The amount of the acid formed by hydrating diphosphorus pentoxide or a salt thereof may be a desired amount according to the performance such as sensitivity and fog, but is preferably 0.1 to 500 mg / m ² , preferably 0.5 to 100 mg / m ² is more preferable.

  The photothermographic material of the present invention contains a reducing agent. The reducing agent used in the present invention is any substance, preferably an organic substance, that reduces silver ions to metallic silver. Conventional photographic developers such as phenidone, hydroquinone and catechol are useful, but hindered phenol reducing agents are preferred. The reducing agent is preferably contained in an amount of 5 to 50 mol%, more preferably 10 to 40 mol%, based on 1 mol of silver on the surface having the image forming layer. The addition layer of the reducing agent may be any layer on the image forming layer side with respect to the support. When added to a layer other than the image forming layer, it is preferably used in a large amount of 10 to 50 mol% with respect to 1 mol of silver. The reducing agent may be a so-called precursor that is derivatized so as to function effectively only during development.

  A wide range of reducing agents can be used in the photothermographic material using an organic silver salt. For example, JP-A-46-6074, 47-1238, 47-33621, 49-46427, 49-115540, 50-14334, 50-36110, 50-147711 51-32632, 51-1023721, 51-32324, 51-51933, 52-84727, 55-108654, 56-146133, 57-82828, 57-82829, JP-A-6-3793, US Pat. No. 3,679,426, 3,751,252, 3,751,255, 3,761,270, 3,782, 949, 3,839,048, 3,928,686, 5,464,738, German Patent 2,321,328, European Patent Publication 692,73 It can be used reducing agents disclosed in issue like. Specifically, amidooximes such as phenylamidooxime, 2-thienylamidooxime and p-phenoxyphenylamidooxime; azines such as 4-hydroxy-3,5-dimethoxybenzaldehyde azine; 2,2′-bis (hydroxymethyl) A combination of an aliphatic carboxylic acid aryl hydrazide and ascorbic acid, such as a combination of propionyl-β-phenylhydrazine and ascorbic acid; a combination of polyhydroxybenzene and hydroxylamine, reductone and / or hydrazine (hydroquinone and bis (ethoxy Ethyl) hydroxylamine, piperidinohexose reductone or formyl-4-methylphenylhydrazine in combination); phenylhydroxamic acid, p-hydroxyphenylhydroxamic acid and β-arininhydro Hydroxamic acids such as xamic acid; combinations of azine and sulfonamidophenol (phenothiazine and 2,6-dichloro-4-benzenesulfonamidophenol, etc.); ethyl-α-cyano-2-methylphenyl acetate, ethyl-α-cyano Α-cyanophenylacetic acid derivatives such as phenylacetate; 2,2′-dihydroxy-1,1′-binaphthyl, 6,6′-dibromo-2,2′-dihydroxy-1,1′-binaphthyl and bis (2- Bis-β-naphthol as exemplified by hydroxy-1-naphthyl) methane; bis-β-naphthol and 1,3-dihydroxybenzene derivatives (such as 2,4-dihydroxybenzophenone or 2 ', 4'-dihydroxyacetophenone) 5-pyrazolo such as 3-methyl-1-phenyl-5-pyrazolone Reductones such as those exemplified by dimethylaminohexose reductone, anhydrodihydroaminohexose reductone and anhydrodihydropiperidone hexose reductone; 2,6-dichloro-4-benzenesulfonamidophenol and p- Sulfonamide phenol-based reducing agents such as benzenesulfonamidophenol; 2-phenylindane-1,3-dione and the like; Chromans such as 2,2-dimethyl-7-t-butyl-6-hydroxychroman; 2,6-dimethoxy 1,4-dihydropyridines such as 3,5-dicarboethoxy-1,4-dihydropyridine; bisphenol (bis (2-hydroxy-3-tert-butyl-5-methylphenyl) methane, 2,2-bis (4 -Hydroxy-3-methylphenyl) propane, 4,4-ethylide -Bis (2-t-butyl-6-methylphenol), 1,1, -bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane and 2,2-bis (3 Ascorbic acid derivatives (1-ascorbyl palmitate, ascorbyl stearate, etc.); and aldehydes and ketones such as benzyl and biacetyl; 3-pyrazolidone and certain indan- 1,3-dione; chromanol (tocopherol and the like) and the like. Particularly preferred reducing agents are bisphenol and chromanol.

  When a reducing agent is used, it may be added by any method such as an aqueous solution, an organic solvent solution, a powder, a solid fine particle dispersion, or an emulsified dispersion. The solid fine particle dispersion is performed by a known finer means (ball mill, vibrating ball mill, sand mill, colloid mill, jet mill, roller mill, etc.). A dispersion aid may be used when dispersing the solid fine particles.

  If the photothermographic material contains an additive known as a “coloring agent” that improves the image, the optical density may increase. The toning agent can also be advantageous in forming a black silver image. The toning agent is preferably included in the layer on the image forming layer side with respect to the support in an amount of 0.1 to 50% mol per mol of silver, and more preferably 0.5 to 20% mol. The toning agent may be a so-called precursor that is derivatized to function effectively only during development.

  A wide range of colorants can be used in the photothermographic material. For example, JP-A Nos. 46-6077, 47-10282, 49-5019, 49-5020, 49-91215, 49-91215, 50-2524, 50-32927 50-67132, 50-67641, 50-114217, 51-3223, 51-27923, 52-14788, 52-99813, 53-1020, 53-76020, 54-156524, 54-156525, 61-183642, JP-A-4-56848, JP-B-49-10727, 54-20333, US Pat. No. 3,080,254 No. 3,446,648, No. 3,782,941, No. 4,123,282, No. 4,510,236, British Patent No. 1,380,7 No. 5, it is possible to use a color tone agent disclosed in Belgian Patent 841,910 No. like. Specific examples include phthalimide and N-hydroxyphthalimide; succinimide, pyrazolin-5-one, and quinazolinone, 3-phenyl-2-pyrazolin-5-one, 1-phenylurazole, quinazoline, and 2,4-thiazolidinedione. Such as cyclic imide; naphthalimide (N-hydroxy-1,8-naphthalimide, etc.); cobalt complex (cobalt hexamine trifluoroacetate, etc.); 3-mercapto-1,2,4-triazole, 2,4-dimercapto Mercaptans exemplified by pyrimidine, 3-mercapto-4,5-diphenyl-1,2,4-triazole and 2,5-dimercapto-1,3,4-thiadiazole; N- (aminomethyl) aryl dicarboximide , ((N, N-dimethylaminomethyl) phthale And N, N- (dimethylaminomethyl) -naphthalene-2,3-dicarboximide); and blocked pyrazoles, isothiuronium derivatives and certain photobleaching agents (N, N′-hexamethylenebis (1 -Carbamoyl-3,5-dimethylpyrazole and the like), 1,8- (3,6-diazaoctane) bis (isothiuronium trifluoroacetate) and 2- (tribromomethylsulfonyl) -benzothiazole; and 3-ethyl- 5-[(3-ethyl-2-benzothiazolinylidene) -1-methylethylidene] -2-thio-2,4-oxazolidinedione; phthalazinone, phthalazinone derivatives or metal salts, or 4- (1-naphthyl) Phthalazinone, 6-chlorophthalazinone, 5,7-dimethoxyphthalazinone and 2,3- Derivatives such as hydro-1,4-phthalazinedione; combinations of phthalazinone and phthalic acid derivatives (phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid, tetrachlorophthalic anhydride, etc.); phthalazine, phthalazine derivatives (4- (1-naphthyl) phthalazine, 6-chlorophthalazine, 5,7-dimethoxyphthalazine, 6-isobutylphthalazine, 6-tert-butylphthalazine, 5,7-dimethylphthalazine, and 2,3-dihydrophthal Derivatives of azine, etc.) or metal salts; combinations of phthalazine and its derivatives and phthalic acid derivatives (phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid, tetrachlorophthalic anhydride, etc.); quinazolinedione, benzoxazine or naphthoxazine Derivatives: Halogenation in situ as well as color modifiers Rhodium complexes that also function as a source of halide ions for silver formation (such as ammonium hexachlororhodium (III), rhodium bromide, rhodium nitrate and potassium hexachlororhodium (III)); inorganic peroxides and persulfates ( Ammonium persulfide and hydrogen peroxide); 1,3-benzoxazine-2,4-dione, 8-methyl-1,3-benzoxazine-2,4-dione and 6-nitro-1,3-benzzoxazine Benzoxazine-2,4-diones such as 2,4-dione; pyrimidines and asymmetric-triazines (2,4-dihydroxypyrimidine, 2-hydroxy-4-aminopyrimidine, etc.), azauracil, and tetraazapentalene derivatives (3,6-Dimercapto-1,4-diphenyl-1H, 4H-2,3a, 5,6a-tetraza Ntaren, and 1,4-di (o-chlorophenyl) -3,6-dimercapto-1H, 4H-2, 3a, there is 5,6a- tetra THE pentalene) or the like.

  In the present invention, a phthalazine derivative represented by the general formula (F) described in JP-A No. 2000-35631 is preferably used as a color toning agent. Specifically, the colorants for which A-1 to A-10 described in the publication are preferably used may be added by any method such as a solution, a powder, or a solid fine particle dispersion. The solid fine particle dispersion is performed by a known finer means (ball mill, vibrating ball mill, sand mill, colloid mill, jet mill, roller mill, etc.). A dispersion aid may be used when dispersing the solid fine particles.

  The film surface pH of the photothermographic material of the present invention before heat development is preferably 6.0 or less, and more preferably 5.5 or less. The lower limit is not particularly limited, but is about 3. For the adjustment of the film surface pH, it is preferable to use an organic acid such as a phthalic acid derivative, a non-volatile acid such as sulfuric acid, and a volatile base such as ammonia from the viewpoint of reducing the film surface pH. In particular, ammonia is easily volatilized and can be removed before the coating process or thermal development, which is preferable for achieving a low film surface pH. A method for measuring the film surface pH is described in paragraph number “0123” of JP-A No. 2000-284399.

  In the present invention, silver halide emulsions and / or organic silver salts are further protected against the formation of additional fog by antifoggants, stabilizers and stabilizer precursors, reducing sensitivity during inventory storage. On the other hand, it can be stabilized. Suitable antifoggants, stabilizers and stabilizer precursors that can be used alone or in combination are the thiazonium salts described in U.S. Pat. Nos. 2,131,038 and 2,694,716, U.S. Pat. Azaindene described in U.S. Pat. Nos. 886,437 and 2,444,605, mercury salt described in U.S. Pat. No. 2,728,663, urazole described in U.S. Pat. No. 3,287,135, U.S. Pat. Sulfocatechol described in No. 652, oxime described in British Patent No. 623,448, nitrone, nitroindazole, polyvalent metal salt described in US Pat. No. 2,839,405, described in US Pat. No. 3,220,839 And the palladium, platinum and gold salts described in US Pat. Nos. 2,566,263 and 2,597,915, US Pat. , 665 and 4,442,202, U.S. Pat. Nos. 4,128,557 and 4,137,079, 4,138,365 and 4,459,350. And the phosphorus compounds described in U.S. Pat. No. 4,411,985.

The photothermographic material may contain benzoic acids for the purpose of increasing sensitivity and preventing fogging. The benzoic acid may be any benzoic acid derivative, but preferably in U.S. Pat. Nos. 4,784,939, 4,152,160, JP-A-9-329863, 9-329864, 9-281638, etc. And the compounds described. Benzoic acids may be added to any layer of the photothermographic material, but are preferably added to the layer on the image forming layer side with respect to the support, and more preferably to the organic silver salt-containing layer. Benzoic acids may be added in any step of preparing the coating solution, and when added to the organic silver salt-containing layer, any step from the preparation of the organic silver salt to the preparation of the coating solution may be performed. Immediately before is preferable. The benzoic acid may be added by any method such as powder, solution, fine particle dispersion and the like. Moreover, you may add as a solution mixed with other additives, such as a sensitizing dye, a reducing agent, and a color toning agent. The amount of benzoic acid added may be any amount, but is preferably 1 × 10 ⁻⁶ to 2 mol, more preferably 1 × 10 ^{−3 to} 0.5 mol, per mol of silver.

Antifoggants particularly preferably used in the present invention are organic halides such as JP-A-50-119624, JP-A-50-120328, JP-A-51-121332, JP-A-54-58022, JP-A-56-70543, 56-99335, 59-90842, 61-129642, 62-129845, JP-A-6-208191, 7-5621, 7-27881, 8-15809 And compounds disclosed in US Pat. Nos. 5,340,712, 5,369,000, and 5,464,737. A hydrophilic organic halide represented by the formula (P) described in JP-A No. 2000-284399 is preferably used as an antifoggant. Specifically, (P-1) to (P-118) described in the publication are preferably used. The addition amount of the organic halide is expressed as a molar amount (mol / mol Ag) relative to 1 mol of Ag, preferably 1 × 10 ⁻⁵ to 2 mol / mol Ag, more preferably 5 × 10 ⁻⁵ to 1 mol / mol. Ag, more preferably 1 × 10 ^{−4 to} 5 × 10 ⁻¹ mol / mol Ag. These may use only 1 type or may use 2 or more types together.

A salicylic acid derivative represented by the formula (Z) described in JP-A No. 2000-284399 is preferably used as an antifoggant. Specifically, (A-1) to (A-60) described in the publication are preferable. The addition amount of the salicylic acid derivative represented by the formula (Z) is expressed as a molar amount (mol / mol Ag) relative to 1 mol of Ag, preferably 1 × 10 ^{−5 to} 5 × 10 ⁻¹ mol / mol Ag, and more preferably Is 5 × 10 ⁻⁵ to 1 × 10 ⁻¹ mol / mol Ag, more preferably 1 × 10 ^{−4 to} 5 × 10 ⁻² mol / mol Ag. These may use only 1 type or may use 2 or more types together. As an antifoggant preferably used in the present invention, a formalin scavenger is effective. For example, a compound represented by the formula (S) described in JP-A No. 2000-221634 and its exemplified compounds (S-1) to (S- 24).

  The antifoggant used in the present invention is water or a suitable organic solvent such as alcohols (methanol, ethanol, propanol, fluorinated alcohol), ketones (acetone, methyl ethyl ketone), dimethylformamide, dimethyl sulfoxide, methyl cellosolve, etc. It can be used by dissolving. In addition, it is dissolved by using a well-known emulsification dispersion method using an oil such as dibutyl phthalate, tricresyl phosphate, glyceryl triacetate or diethyl phthalate, or an auxiliary solvent such as ethyl acetate or cyclohexanone, and mechanically emulsified dispersion. Can be used. Alternatively, the powder can be dispersed and used in water by a ball mill, a colloid mill, a sand grinder mill, a manton gourin, a microfluidizer or ultrasonic waves by a method known as a solid dispersion method.

  The antifoggant may be added to the image forming layer side of the support, that is, the image forming layer or any other layer on this layer side, but it must be added to the image forming layer or a layer adjacent thereto. Is preferred. In the case of a photothermographic material, the image forming layer is a layer containing a reducible silver salt (organic silver salt), and more preferably an image forming layer containing a photosensitive silver halide.

  The photothermographic material can contain a mercapto compound, a disulfide compound, and a thione compound for the purpose of controlling development by suppressing or accelerating development and improving storage stability before and after development. When a mercapto compound is used, it may have any structure, but those represented by Ar-SM and Ar-SS-Ar are preferred. In the formula, M is a hydrogen atom or an alkali metal atom, and Ar is an aromatic ring or condensed aromatic ring having one or more nitrogen, sulfur, oxygen, selenium or tellurium atoms. Preferably, the heteroaromatic ring is benzimidazole, naphthimidazole, benzothiazole, naphthothiazole, benzoxazole, naphthoxazole, benzoselenazole, benzotelrazole, imidazole, oxazole, pyrazole, triazole, thiadiazole, tetrazole, triazine, pyrimidine, pyridazine , Pyrazine, pyridine, purine, quinoline or quinazolinone. This heteroaromatic ring can be, for example, halogen (bromine and chlorine), hydroxyl, amino, carboxyl, alkyl (having one or more carbon atoms, preferably having 1 to 4 carbon atoms), alkoxy (one or more carbons) You may have what is selected from the substituent group which consists of an atom, Preferably it has 1-4 carbon atoms) and aryl (which may have a substituent). Examples of the mercapto-substituted heteroaromatic compound 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-mercap Pyrimidine 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, and the like. It is not limited. The addition amount of these mercapto compounds is preferably in the range of 0.0001 to 1.0 mol, more preferably 0.001 to 0.3 mol, per mol of silver in the image forming layer.

  The photothermographic material of the invention has an image forming layer containing an organic silver salt, a reducing agent and a photosensitive silver halide on a support, and at least one protective layer is provided on the image forming layer. It is preferable. The support preferably has at least one back layer on the opposite side (back surface) to the image forming layer, and a polymer latex is used as a binder for the image forming layer, the protective layer, and the back layer. By using polymer latex for these layers, aqueous coating using a solvent (dispersion medium) containing water as a main component becomes possible, which is advantageous in terms of environment and cost, and generation of wrinkles during thermal development. No photothermographic material can be obtained. Further, by using a support subjected to a predetermined heat treatment, a photothermographic material having little dimensional change before and after thermal development can be obtained.

  The polymer latex described below is preferably used as the binder used in the present invention. At least one of the image forming layers containing the photosensitive silver halide of the photothermographic material is preferably an image forming layer using the polymer latex described below in an amount of 50% by mass or more of the total binder. The polymer latex may be used not only for the image forming layer but also for the protective layer and the back layer. In particular, when a photothermographic material is used for printing applications in which dimensional change is a problem, the polymer latex is also used for the protective layer and the back layer. It is preferable to use a polymer latex. However, the “polymer latex” referred to here is one in which a water-insoluble hydrophobic polymer is dispersed as fine particles in a water-soluble dispersion medium. As the dispersion state, the polymer is emulsified in a dispersion medium, emulsion-polymerized, micelle-dispersed, or partly hydrophilic in the polymer molecule and the molecular chain itself is molecularly dispersed. Any of these may be used. As for polymer latex, “Synthetic resin emulsion (Hiraku Okuda, Hiroshi Inagaki, published by Kobunshi Publishing Co., Ltd. (1978))”, “Application of synthetic latex (Takaaki Sugimura, Ikuo Kataoka, Junichi Suzuki, Keiji Kasahara, Takashi Kasahara) "Molecular Publications (1993))", "Synthetic Latex Chemistry (written by Soichi Muroi, published by High Polymers Publication (1970))" and the like. The average particle size of the dispersed particles is preferably 1 to 50,000 nm, more preferably about 5 to 1,000 nm. The particle size distribution of the dispersed particles is not particularly limited, and may have a wide particle size distribution or a monodispersed particle size distribution.

  The polymer latex may be a so-called core / shell type latex other than a normal polymer latex having a uniform structure. In this case, it may be preferable to change the glass transition temperature (Tg) between the core and the shell. The preferred range of Tg of the polymer latex preferably used in the present invention differs between the protective layer, the back layer and the image forming layer. The image forming layer preferably has a temperature of −30 to 40 ° C. in order to promote diffusion of a useful photograph material during heat development. When used for a protective layer or a back layer, Tg of 25 to 70 ° C. is preferable for contact with various devices. The minimum film-forming temperature (MFT) of the polymer latex used in the present invention is preferably -30 to 90 ° C, more preferably about 0 to 70 ° C. In order to control MFT, a film-forming aid may be added. The film-forming aid, also called a plasticizer, is an organic compound (usually an organic solvent) that lowers the MFT of the polymer latex, and is described, for example, in the aforementioned “Synthetic Latex Chemistry”.

  Examples of the polymer species used for the polymer latex include acrylic resins, vinyl acetate resins, polyester resins, polyurethane resins, rubber resins, vinyl chloride resins, vinylidene chloride resins, polyolefin resins, and copolymers thereof. The polymer may be a linear polymer, a branched polymer, or a crosslinked polymer. The polymer may be a so-called homopolymer in which a single monomer is polymerized or a copolymer in which two or more monomers are polymerized. In the case of a copolymer, it may be a random copolymer or a block copolymer. The molecular weight of the polymer is 5,000 to 1,000,000, preferably 10,000 to 100,000 in terms of number average molecular weight. When the molecular weight is too small, the mechanical strength of the image forming layer is insufficient, and when the molecular weight is too large, the film formability is poor and both are not preferable.

  Specific examples of the polymer latex used as the binder of the image forming layer of the present invention include methyl methacrylate / ethyl acrylate / methacrylic acid copolymer, methyl methacrylate / butadiene / itaconic acid copolymer, ethyl acrylate / methacrylic acid copolymer, methyl methacrylate / 2. -Ethylhexyl acrylate / styrene / acrylic acid copolymer, styrene / butadiene / acrylic acid copolymer, styrene / butadiene / divinylbenzene / methacrylic acid copolymer, methyl methacrylate / vinyl chloride / acrylic acid copolymer, vinylidene chloride / ethyl acrylate / acrylonitrile / methacrylic acid copolymer And the like. More specifically, a copolymer of methyl methacrylate / ethyl acrylate / methacrylic acid = 33.5 / 50 / 16.5 (mass%), methyl methacrylate / butadiene / itaconic acid = 47.5 / 47.5 / 5 (mass) %), And latex such as ethyl acrylate / methacrylic acid = 95/5 (mass%) copolymer.

  Such polymers are also commercially available. For example, as examples of acrylic resins, Ceviane A-4635, 46583, 4601 (above, manufactured by Daicel Chemical Industries), Nipol LX811, 814, 821, 820, 857 (above, ZEON) ), VONCORT-R3340, R3360, R3370, 4280 (above, manufactured by Dainippon Ink Chemical Co., Ltd.), etc. size, WMS (manufactured by Eastman Chemical Co., Ltd.), etc., polyurethane resins such as HYDRAN AP10, 20, 30, 40 (above, Dainippon Ink Chemical Co., Ltd.) etc., rubber-based resins such as LACSTAR 7310K, 3307B, 4700H, 7132C ( Greater than Japan (Made by Ki Chemical Co., Ltd.), Nipol LX410, 430, 435, 438C (above, manufactured by Nippon Zeon Co., Ltd.) and the like, G351, G576 (made by Nippon Zeon Co., Ltd.), etc. as vinyl chloride resins, and L502, L513 as vinylidene chloride resins, etc. Examples of olefin resins such as Aron D7020, D504, D5071 (above, Mitsui Toatsu) and Aleon D7020, D504, D5071 (above, manufactured by Asahi Kasei Kogyo Co., Ltd.) and the like. These polymers may be used alone or as a blend of two or more as necessary.

  In the image forming layer, the polymer latex is preferably used in an amount of 50% by mass or more of the total binder, but the polymer latex is more preferably used in an amount of 70% by mass or more. If necessary, a hydrophilic polymer such as gelatin, polyvinyl alcohol, methyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, or hydroxypropyl methylcellulose may be added to the image forming layer within a range of 50% by mass or less of the total binder. The addition amount of these hydrophilic polymers is preferably 30% by mass or less, more preferably 15% by mass or less, based on the total binder of the image forming layer.

  The image forming layer is preferably formed by applying and drying an aqueous coating solution. However, “aqueous” as used herein means that 60% by mass or more of the solvent (dispersion medium) of the coating solution is water. As components other than water in the coating solution, water-miscible organic solvents such as methyl alcohol, ethyl alcohol, i-propyl alcohol, methyl cellosolve, ethyl cellosolve, dimethylformamide, ethyl acetate and the like can be used. Specific examples of the solvent composition include the following. Water / methanol = 90/10, water / methanol = 70/30, water / ethanol = 90/10, water / i-propanol = 90/10, water / dimethylformamide = 95/5, water / methanol / dimethylformamide = 80/15/5, water / methanol / dimethylformamide = 90/5/5 (numbers indicate mass%).

The total binder amount in the image forming layer is preferably 0.2 to 30 g / m ² , more preferably 1 to 15 g / m ² . A crosslinking agent for crosslinking, a surfactant for improving coating properties, and the like may be added to the image forming layer. Further, as a binder for the protective layer, polymer latexes having different I / O values obtained by dividing the inorganic value based on the organic conceptual diagram by the organic value described in paragraph Nos. “0025 to 0029” of JP-A No. 2000-267226 These combinations can be preferably used.

  In the present invention, a plasticizer (benzyl alcohol, 2,2,4-trimethylpentanediol-1,3-monoisobutyrate described in paragraph Nos. [0021 to 0025] of JP-A No. 2000-267226 is optionally used. Etc.) can be added to control the film-forming temperature. Further, as described in JP-A-2000-267226, paragraph numbers “0027 to 0028”, a hydrophilic polymer may be added to the polymer binder, and a water-miscible organic solvent may be added to the coating solution. In each layer, a first polymer latex into which functional groups described in JP-A-2000-19678, paragraph numbers “0023 to 0041” are introduced, and a crosslink having a functional group capable of reacting with the first polymer latex. An agent and / or a second polymer latex can also be used.

  The functional group includes a carboxyl group, a hydroxyl group, an isocyanate group, an epoxy group, an N-methylol group, an oxazolinyl group and the like, and as a crosslinking agent, an epoxy compound, an isocyanate compound, a blocked isocyanate compound, a methylol compound, a hydroxy compound, a carboxy compound , Amino compounds, ethyleneimine compounds, aldehyde compounds, halogen compounds and the like. Specific examples of the crosslinking agent include hexamethylene isocyanate, duranate WB40-80D, WX-1741 (manufactured by Asahi Kasei Kogyo Co., Ltd.), Bihijoule 3100 (manufactured by Sumitomo Bayer Urethane Co., Ltd.), Takenate WD725 (manufactured by Takeda Pharmaceutical Co., Ltd.), Aqua Nate 100, 200 (manufactured by Nippon Polyurethane Co., Ltd.), water-dispersed polyisocyanate described in JP-A-9-160172; Sumitex Resin M-3 (manufactured by Sumitomo Chemical Co., Ltd.) as an amino compound; Denacol EX-614B (manufactured by Sumitomo Chemical Co., Ltd.) 2,4 dichloro-6-hydroxy-1,3,5-triazine sodium etc. are mentioned as a halogen compound.

The total binder amount for the image forming layer is preferably 0.2 to 30 g / m ² , more preferably 1.0 to 15 g / m ² . The total binder amount for the protective layer is preferably 0.2 to 10.0 g / m ² , more preferably 0.5 to 6.0 g / m ² . The total amount of binder for the back layer is preferably 0.01 to 10.0 g / m ² , more preferably 0.05 to 5.0 g / m ² .

  Each of these layers may be provided in two or more layers. When there are two or more image forming layers, it is preferable to use a polymer latex as a binder for all layers. The protective layer is a layer provided on the image forming layer, and there may be two or more layers, but it is preferable to use a polymer latex for at least one, particularly the outermost protective layer. The back layer is a layer provided on the undercoat layer on the back surface of the support, and there may be two or more layers, but it is preferable to use a polymer latex for at least one, particularly the outermost back layer.

A slipping agent can be used in the photothermographic material. The slip agent referred to in the present invention means a compound that, when present on the surface of the object, reduces the coefficient of friction of the object surface as compared with the case where it does not exist. The type is not particularly limited. Examples of the slip agent used in the present invention include compounds described in paragraph Nos. “0061 to 0064” of JP-A No. 11-84573. Specific examples of preferable slipping agents include cellosol 524 (main component carnauba wax), polylon A, 393, H-481 (main component polyethylene wax), high micron G-110 (main component ethylenebisstearic acid amide), high micron. Examples thereof include G-270 (main component stearate amide) (manufactured by Chukyo Yushi Co., Ltd.), W-1 (C ₁₆ H ₃₃ OSO ₃ Na), W-2 (C ₁₈ H ₃₇ OSO ₃ Na), and the like. The usage-amount of a slip agent is 0.1-50 mass% of the binder amount of an addition layer, Preferably it is 0.5-30 mass%.

  In the present invention, as described in JP-A No. 2000-171935, the preheating unit is conveyed by a counter roller, and the heat development processing unit smoothes the back surface on the opposite side by driving the roller on the side having the image forming layer. In the case of using a heat development processing apparatus that slides and conveys the surface, the ratio of the friction coefficient between the outermost surface layer on the side having the image forming layer and the outermost surface layer of the back surface at the development processing temperature is 1 The upper limit is not particularly limited, but is about 30. Further, μb is 1.0 or less, preferably 0.05 to 0.8. This value is obtained by the following equation.

Ratio of friction coefficient = dynamic friction coefficient between the roller member of the heat developing machine and the surface having the image forming layer (μe) / dynamic friction coefficient between the smooth surface member of the heat developing machine and the back surface (μb)
The slipperiness of the surface having the heat development processor member and the image forming layer at the heat development processing temperature and / or the outermost layer on the opposite side can be changed by adding a slipping agent to the outermost surface layer and changing its addition amount. Can be adjusted.

  JP-A 64-20544, JP-A-1-180537, JP-A-209443, JP-A-285939, JP-A-1-296243, JP-A-2-24649, JP-A-2-24648 are provided on both sides of the support. No. 2-184844, No. 3-109545, No. 3-137737, No. 3-141346, No. 3-141347, No. 4-96055, U.S. Pat. -68344, Patent 2,557,641, page 2, right column, line 20 to page 3, right column, line 30; JP-A 2000-39684, paragraph number "0020-0037" It is preferable to provide an undercoat layer containing a vinylidene chloride copolymer containing 70% by mass or more of the above repeating unit.

  When the vinylidene chloride monomer is less than 70% by mass, sufficient moisture resistance cannot be obtained, and the dimensional change over time after heat development becomes large. The vinylidene chloride copolymer preferably contains a repeating unit of a vinyl monomer containing a carboxyl group as another constituent repeating unit of the vinylidene chloride monomer. The inclusion of such a repeating unit causes the polymer to crystallize only with the vinyl chloride monomer, making it difficult to form a uniform film when the moisture-proof layer is applied, and to stabilize the polymer. This is because a vinyl monomer containing a carboxyl group is indispensable for this purpose. The molecular weight of the vinylidene chloride copolymer is preferably 45,000 or less, more preferably 10,000 to 45,000 in terms of mass average molecular weight. When the molecular weight increases, the adhesion between the vinylidene chloride copolymer layer and a support layer such as polyester tends to deteriorate.

  The content of the vinylidene chloride copolymer is 0.3 μm or more, preferably 0.3 to 4 μm, as a total film thickness per one side of the undercoat layer containing the copolymer. The vinylidene chloride copolymer layer as the undercoat layer is preferably provided as the first undercoat layer that is directly provided on the support. Usually, one layer is provided on each side, but in some cases two layers are provided. You may provide above. When a multilayer structure of two or more layers is used, the total amount of vinylidene chloride copolymer may be in the range of 0.6 to 8.0 μm. Such a layer may contain a crosslinking agent, a matting agent and the like in addition to the vinylidene chloride copolymer. In addition to the vinylidene chloride copolymer layer, the support may be coated with an undercoat layer using SBR, polyester, gelatin or the like as a binder. These undercoat layers may have a multilayer structure, or may be provided on one side or both sides of the support. The thickness of the undercoat layer (per layer) is generally from 0.01 to 5 μm, more preferably from 0.05 to 1 μm.

  Various supports can be used for the photothermographic material. Typical supports include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), cellulose nitrate, cellulose ester, polyvinyl acetal, syndiotactic polystyrene (sPS), polycarbonate (PC), and polyethylene on both sides. Examples thereof include a coated paper support. Of these, biaxially stretched polyester, particularly PET, is preferable from the viewpoint of strength, dimensional stability, chemical resistance, and the like. The thickness of the support is preferably 90 to 180 μm as the base thickness excluding the undercoat layer. The support used for the photothermographic material of the present invention is biaxially stretched as described in JP-A Nos. 10-48772, 10-10676, 10-10777, 11-65025, and 11-138648. In order to alleviate the internal strain that sometimes remains in the film and to eliminate the heat shrinkage strain that occurs during the heat development process, polyester that has been heat-treated at a temperature range of 130 to 185 ° C., particularly PET, is preferably used. The dimensional change rate of the support after heating at 120 ° C. for 30 seconds is −0.03 to + 0.01% in the machine direction (MD) and 0 to 0.04% in the transverse direction (TD). It is preferable.

  In the photothermographic material, the conductivity described in paragraph Nos. “0040 to 0051” of JP-A No. 11-84573 is used for the purpose of reducing dust adhesion, preventing the generation of static marks, and preventing the conveyance failure in the automatic conveyance process. Antistatic treatment can be performed using a metal oxide and / or a fluorine-based surfactant. Examples of the conductive metal oxide include acicular conductive tin oxide doped with antimony described in U.S. Pat. No. 5,575,957 and paragraph Nos. [0012 to 0020] of JP-A-11-223901, Fibrous tin oxide doped with antimony described in No. 29134 is preferably used.

The surface specific resistance (surface resistivity) of the metal oxide-containing layer is 10 ¹² Ω or less, preferably 10 ¹¹ Ω or less in an atmosphere of 25 ° C. and RH (relative humidity) 20%. Thereby, good antistatic properties can be obtained. The lower limit of the surface resistivity at this time is not particularly limited, but is usually about 10 ⁷ Ω.

  The Beck smoothness of at least one of the surface having the image forming layer of the photothermographic material of the present invention and the surface of the outermost layer on the opposite side, preferably both, is 2,000 seconds or less, more preferably 10-2. 000 seconds. The Beck smoothness can be easily determined by Japanese Industrial Standard (JIS) P8119 “Smoothness test method using Beck tester for paper and paperboard” and TAPPI standard method T479. The Beck smoothness of the outermost layer on the surface having the image forming layer of the photothermographic material and the outermost layer on the opposite side thereof is as described in paragraphs “0052 to 0059” of JP-A No. 11-84573. It can adjust by changing suitably the particle size and addition amount of the matting agent to be contained in.

  In the present invention, a water-soluble polymer is preferably used as a thickener for imparting coating properties, and may be a natural product or a synthetic polymer, and the type thereof is not particularly limited. Specifically, natural products include starches (corn starch, starch, etc.), seaweeds (agar, sodium alginate, etc.), vegetable stickies (gum arabic, etc.), animal proteins (glue, casein, gelatin, egg white, etc.) , Fermentation adhesives (pullulan, dextrin, etc.), semi-synthetic polymer starches (soluble starch, carboxyl starch, dextran, etc.), celluloses (viscose, methylcellulose, ethylcellulose, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropyl) Cellulose, hydroxypropylmethylcellulose, etc.) and synthetic polymers (polyvinyl alcohol, polyacrylamide, polyvinylpyrrolidone, polyethylene glycol, polypropylene glycol, polyvinyl ether, poly Tylene imine, polystyrene sulfonic acid or copolymer thereof, polyvinyl sulfonic acid or copolymer thereof, polyacrylic acid or copolymer thereof, acrylic acid or copolymer thereof, maleic acid copolymer, maleic acid monoester copolymer Polymer, acryloylmethylpropane sulfonic acid or a copolymer thereof, and the like.

  Among these, water-soluble polymers preferably used are sodium alginate, gelatin, dextran, dextrin, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinyl alcohol, polyacrylamide, polyvinyl pyrrolidone, polyethylene glycol, polypropylene glycol, polystyrene sulfonic acid. Or a copolymer thereof, polyacrylic acid or a copolymer thereof, a maleic acid monoester copolymer, an acryloylmethylpropane sulfonic acid or a copolymer thereof. Particularly preferred thickeners include gelatin, dextran, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, polyacrylamide, polyvinyl pyrrolidone, polystyrene sulfonic acid or a copolymer thereof, polyacrylic acid or a copolymer thereof, maleic acid mono Ester copolymers and the like. These compounds are described in detail in “Applications and Markets of New Water-Soluble Polymers” (issued by CMC, edited by Shinji Nagatomo, published on November 4, 1988).

  The amount of the water-soluble polymer used as the thickener is not particularly limited as long as the viscosity increases when added to the coating solution, but generally the concentration in the solution is 0.01 to 30% by mass, more preferably 0.05. -20% by mass, particularly preferably 0.1-10% by mass. The viscosity obtained by these is preferably 1 to 200 mPa · s, more preferably 5 to 100 mPa · s as an increase from the initial viscosity. In addition, a viscosity shows the value measured at 25 degreeC with the B-type rotational viscometer. When adding to a coating solution, it is generally desirable to add the thickener as a dilute solution as much as possible. Moreover, it is preferable to perform sufficient stirring at the time of addition.

  The surfactant used in the present invention is described below. Surfactants are classified into dispersants, coating agents, wetting agents, antistatic agents, photographic performance modifiers, etc. depending on the purpose of use, but the purpose is to select and use the surfactants described below as appropriate. Can be achieved. As the surfactant used in the present invention, any of nonionic, anionic, cationic and betaine can be used. Further, a fluorine-based surfactant is also preferably used.

  Preferred nonionic surfactants include polyoxyethylene, polyoxypropylene, polyoxybutylene, polyglycidyl and sorbitan. Specifically, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ether, Oxyethylene-polyoxypropylene glycol, polyhydric alcohol fatty acid partial ester, polyoxyethylene polyhydric alcohol fatty acid partial ester, polyoxyethylene fatty acid ester, polyglycerin fatty acid ester, fatty acid diethanolamide, triethanolamine fatty acid partial ester it can.

  Examples of anionic surfactants include carboxylate, sulfate, sulfonate, and phosphate ester salts. Typical examples include fatty acid salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, and alkyl salts. Sulfonates, α-olefin sulfonates, dialkylsulfosuccinates, α-sulfonated fatty acid salts, N-methyl-N-oleyl taurine, petroleum sulfonates, alkyl sulfates, sulfated fats and oils, polyoxyethylene alkyls Examples thereof include ether sulfates, polyoxyethylene alkyl phenyl ether sulfates, polyoxyethylene styrenated phenyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, naphthalene sulfonate formaldehyde condensates, and the like.

  Examples of the cationic surfactant include amine salts, quaternary ammonium salts, pyridium salts, etc., and primary to tertiary fatty amine salts, quaternary ammonium salts (tetraalkylammonium salts, trialkylbenzylammonium salts). , Alkyl pyridium salts, alkyl imidazolium salts, and the like.

  Examples of the betaine surfactant include carboxybetaine and sulfobetaine, and examples thereof include N-trialkyl-N-carboxymethylammonium betaine and N-trialkyl-N-sulfoalkyleneammonium betaine. These surfactants are described in “Application of Surfactant” (Shoshobo, Takao Karie, published on September 1, 1980).

In the present invention, the amount of the surfactant used is not particularly limited as long as the desired surface active characteristics can be obtained. The coating amount of the fluorine-containing surfactant is preferably 0.01 to 250 mg per 1 m ² .

Specific examples of preferable surfactants are shown below, but are not limited thereto (wherein —C ₆ H ₄ — represents a phenylene group).

WA-1: C ₁₆ H ₃₃ O (CH ₂ CH ₂ O) ₁₀ H
_{WA-2: C 9 H 19} -C 6 H 4 -O (CH 2 CH 2 O) 12 H
WA-3: Sodium dodecylbenzenesulfonate WA-4: Sodium tri (i-propyl) naphthalenesulfonate WA-5: Sodium tri (i-butyl) naphthalenesulfonate WA-6: Sodium dodecyl sulfate WA-7: α- sulfosuccinate, di (2-ethylhexyl) ester sodium salt _{WA-8: C 8 H 17} -C 6 H 4 - (CH 2 CH 2 O) 3 (CH 2) 2 SO 3 K
WA-9: cetyltrimethylammonium chloride _{WA-10: C 11 H 23} CONHCH 2 CH 2 N + (CH 3) 2 CH 2 COO -
WA-11: C ₈ F ₁₇ SO ₂ N (C ₃ H ₇ ) (CH ₂ CH ₂ O) ₁₆ H
_{WA-12: C 8 F 17} SO 2 N (C 3 H 7) CH 2 COOK
WA-13: C ₈ F ₁₇ SO ₃ K
_{WA-14: C 8 F 17} SO 2 N (C 3 H 7) (CH 2 CH 2 O) 4 (CH 2) 4 SO 3 Na
_{WA-15: C 8 F 17} SO 2 N (C 3 H 7) (CH 2) 3 OCH 2 CH 2 N + (CH 3) 3 · CH 3 -C 6 H 4 -SO 3 -
_{WA-16: C 8 F 17} SO 2 N (C 3 H 7) CH 2 CH 2 CH 2 N + (CH 3) 2 CH 2 COO -
As a preferred embodiment of the present invention, an intermediate layer may be provided as necessary in addition to the image forming layer and the protective layer. For the purpose of improving productivity and the like, it is preferable to apply these plural layers simultaneously in an aqueous system. Examples of the coating method include extrusion coating, slide bead coating, curtain coating, and the like, but the slide bead coating method shown in FIG. 1 of JP-A-2000-2964 is particularly preferable. In the case of a silver halide light-sensitive material using gelatin as a main binder, it is rapidly cooled in a first drying zone provided downstream of the coating die. As a result, gelatin is gelled and the coating film is cooled and solidified. The coating film that has been cooled and solidified and stopped flowing is guided to the subsequent second drying zone, and the solvent in the coating solution is volatilized in the subsequent drying zone to form a film. As a drying method after the second drying zone, an air loop method in which a jet is blown from a U-shaped duct to a support supported by a roller, or a support is wound around a cylindrical duct in a string form to carry and dry. Examples include a winding method (air floating method). When layer formation is performed using a coating liquid whose main component of the binder is polymer latex, the flow of the coating liquid cannot be stopped by rapid cooling, and thus preliminary drying may be insufficient only in the first drying zone. . In this case, in the drying method used in the silver halide light-sensitive material, flow unevenness and dry unevenness occur, and a serious defect is likely to occur on the coated surface.

  A preferable drying method in the present invention is that the drying is performed in the horizontal drying zone at least until the constant rate drying is completed, regardless of the first drying zone or the second drying zone as described in JP-A-2000-2964. It is a method to make it. The conveyance of the support from immediately after coating to the horizontal drying zone may or may not be horizontal, and the rising angle of the coating machine with respect to the horizontal direction may be between 0 and 70 °. Further, the horizontal drying zone of the present invention is not limited to horizontal transport as long as the support is transported within ± 15 ° up and down with respect to the horizontal direction of the coating machine.

  The constant rate drying in the present invention means a drying process in which the liquid film temperature is constant and all the inflowing heat is used for evaporation of the solvent. Decreasing drying means that at the end of drying, the drying rate decreases due to various factors (such as the internal diffusion of moisture in the material, rate of receding evaporation), and the applied heat is also used to increase the liquid film temperature. Means drying process. The critical moisture content for shifting from the constant rate process to the decreasing process is 200 to 300%. When the constant rate drying is completed, the drying proceeds sufficiently until the flow stops, so that a drying method such as a silver halide photosensitive material can also be adopted. It is preferable to dry in a horizontal drying zone to the drying point. The drying conditions for forming the image forming layer and / or protective layer are such that the liquid film surface temperature during constant rate drying is higher than the minimum film forming temperature of the polymer latex (MTF: usually 3 to 5 ° C. higher than the Tg of the polymer). It is preferable to do. Usually, it is often 25 to 40 ° C. due to the limitation of the production equipment. In addition, the dry bulb temperature at the time of reduced rate drying is preferably a temperature lower than the Tg of the support (usually 80 ° C. or less in the case of PET). The liquid film surface temperature in the present invention refers to the solvent liquid film surface temperature of the coating liquid film coated on the support, and the dry bulb temperature means the temperature of the drying air in the drying zone. When dried under conditions where the liquid film surface temperature during constant rate drying is low, drying tends to be insufficient. For this reason, especially the film forming property of a protective layer falls remarkably and it becomes easy to produce a crack on the film | membrane surface. In addition, the film strength is weakened, and serious problems such as being easily scratched during conveyance by an exposure machine or a heat development machine are likely to occur.

  On the other hand, when dried under conditions where the liquid film surface temperature is high, the protective layer mainly composed of the polymer latex forms a film quickly, while the lower layer such as the image forming layer stops fluidity. As a result, unevenness is likely to occur on the surface. Further, when excessive heat higher than Tg is applied to the support, the dimensional stability and curling resistance of the photosensitive material tend to deteriorate. The same applies to sequential coating, in which the lower layer is applied and dried, and then the upper layer is applied. In particular, as a coating liquid property for performing simultaneous multilayer coating in which the upper layer is applied before drying the lower layer and both layers are dried simultaneously. The pH difference between the coating solution for the image forming layer and the coating solution for the protective layer is preferably 2.5 or less, and the smaller the pH difference, the better. When the pH difference of the coating solution increases, micro-aggregation tends to occur at the coating solution interface, and a serious surface failure such as coating streaks tends to occur during long continuous coating.

  The viscosity of the coating solution for the image forming layer is preferably 15 to 100 mPa · s, more preferably 30 to 70 mPa · s at 25 ° C. On the other hand, the coating solution viscosity of the protective layer is preferably 5 to 75 mPa · s at 25 ° C., more preferably 20 to 50 mPa · s. These viscosities are measured with a B-type viscometer. The winding after drying is preferably performed under conditions of 20 to 30 ° C. and 45 ± 20% RH (relative humidity), and the winding shape is adjusted to the subsequent processing form, with the surface on the image forming layer side facing outside. Or it may be inside. Further, when the processing form is a roll product, it is also preferable to use a roll form wound on the opposite side of the winding form during processing in order to remove curl generated in the winding form. The relative humidity of the photosensitive material is preferably controlled in the range of 20 to 55% (measured at 25 ° C.).

In a conventional photographic emulsion coating solution, which is a viscous liquid containing silver halide and containing gelatin as a base, bubbles are dissolved and disappeared in the liquid simply by feeding under pressure, and returned to atmospheric pressure during coating. However, there is almost no bubble deposition. However, in the case of an image-forming layer coating solution containing an organic silver salt dispersion and polymer latex as used in the present invention, degassing tends to be insufficient only by pressurized liquid feeding, so that a gas-liquid interface does not occur. It is preferable to defoam by applying ultrasonic vibration while feeding. This defoaming of the coating solution is performed by degassing under reduced pressure before the coating solution is applied, further maintaining a pressurized state of 1.5 kg / cm ² or more, and continuously feeding so that no gas-liquid interface occurs. A method of applying ultrasonic vibration while liquid is preferable. Specifically, the system described in JP-B-55-6405 (page 4, line 20 to page 7, line 11) is preferable. As an apparatus for performing such defoaming, the embodiment shown in Japanese Patent Laid-Open No. 2000-98534 and the apparatus shown in FIG. 3 can be preferably used.

  As a pressurizing condition, 14.7 kPa or more is preferable, and 17.6 kPa or more is more preferable. Although there is no restriction | limiting in particular in the upper limit, Usually, it is about 49 kPa. The sound pressure of the applied ultrasonic wave is 0.2 V or more, preferably 0.5 to 3.0 V. Generally, it is preferable that the sound pressure is high. It becomes a state and causes fogging. Although there is no restriction | limiting in particular in a frequency, Usually, 10 kHz or more, Preferably it is 20-200 kHz. Note that vacuum degassing means that the inside of the tank (preparation tank or storage tank) is hermetically depressurized, the bubble diameter in the coating liquid is increased, the buoyancy is increased, and degassing is performed. Is a pressure condition of −26.7 kPa or lower, preferably −33.3 kPa or lower, and the lowest pressure condition is not particularly limited but is usually about −106.7 kPa. The decompression time is 30 minutes or more, preferably 45 minutes or more, and the upper limit is not particularly limited.

The image forming layer, the protective layer of the image forming layer, the undercoat layer, and the back layer contain a dye for the purpose of preventing halation as described in paragraph No. "0204 to 0208" of JP-A No. 11-84573. Can do. Various dyes and pigments can be used for the image forming layer from the viewpoint of improving the color tone and preventing irradiation. Any dye and pigment may be used for the image forming layer. For example, compounds described in paragraph No. “0297” of JP-A No. 11-119374 can be used. As a method for adding these dyes, any method such as a solution, an emulsion, a solid fine particle dispersion, or a state mordanted in a polymer mordant may be used. The amount of these compounds to be used is determined by the target absorption amount, but generally it is preferably used in the range of 1 × 10 ^{−6 to} 1 g per 1 m ² . When an antihalation dye is used in the present invention, the dye has a desired absorption within a desired range, and the absorption in the visible region is sufficiently small after the treatment, so that any preferable absorbance spectrum shape of the back layer can be obtained. It may be a compound. For example, compounds described in paragraph No. “0300” of JP-A-11-119374 can be used. Further, as described in Belgian Patent No. 733,706, a method of reducing the concentration by dye by decoloring by heating, and as described in JP-A No. 54-17833, the concentration is decreased by decoloring by light irradiation. A method or the like can also be used.

  When the photothermographic material is used as a mask when a printing plate is produced with a PS plate after heat development, the photothermographic material after heat development contains information for setting exposure conditions for the PS plate in a plate making machine, and a mask. Information for setting plate making conditions such as conveyance conditions for the original and the PS plate is 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, Fuji Photo Film Co., Ltd .: plate-making machine S-FNRIII uses a light source having a wavelength of 670 nm as a detector for detecting a registration mark and a barcode reader. In addition, a 670 nm light source is used as a barcode reader for the plate making machine APML series manufactured by Shimizu. That is, when Dmin near 670 nm is high, information on the film cannot be accurately detected, and work errors such as conveyance failure and exposure failure occur in the plate making machine. 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.

The exposure apparatus used for imagewise exposure may be any apparatus that can perform exposure with an exposure time of 10 ⁻⁷ seconds or less. Generally, a laser diode (LD) or a light emitting diode (LED) is used as a light source. The used exposure apparatus is preferably used. In particular, LD is 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. In particular, a semiconductor laser is preferable, and specific examples thereof include In _1-x Ga _x P (˜700 nm), GaAs _1-x P _x (610 to 900 nm), Ga _1-x Al _x As (690 to 900 nm), A semiconductor laser using a material such as InGaAsP (1100 to 1670 nm) AlGaAsSb (1250 to 1400 nm) can be given. The color photosensitive material may be irradiated with light by a YAG laser (1064 nm) that excites an Nb: YAG crystal by a GaAs _x P _1-x light emitting diode in addition to the semiconductor laser. Preferably, it is preferable to use a laser beam selected from 670, 680, 750, 780, 810, 830, and 880 nm.

In the present invention, the second harmonic generation element (SHG element) is a device that converts the wavelength of a laser beam into half by applying a nonlinear optical effect. For example, CD * A as a nonlinear optical crystal is used. And those using KD * P (see Laser Handbook: edited by Laser Society, published December 15, 1982, pages 122-139). In addition, a LiNbO ₃ optical waveguide device in which an optical waveguide in which Li ⁺ is ion-exchanged with H ⁺ in a LiNbO ₃ crystal can be used (NIKKEIELECTRONICS 1986. 7.14 (no. 399) 89-90). In the present invention, an output device described in JP-A-63-226552 can be used.

The 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, the overlap coefficient is preferably 0.2 or more. The energy density at the time of exposure is preferably several μJ / cm ² to several hundred μJ / cm ² . Furthermore, it is preferably several μJ / cm ² to several tens μJ / cm ² .

  The light source scanning method 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 in the case of a cylindrical outer surface system, a multi-channel is preferably used.

  The photothermographic 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, a technique for obliquely entering laser light disclosed in Japanese Patent Laid-Open No. 5-11548 or the like, or a multi-purpose disclosed in International Publication WO95 / 31754, etc. Methods using mode lasers are known and these techniques are preferably used.

  The heat development step of the image forming method using the photothermographic material of the present invention may be any method, but usually the image is exposed to an imagewise exposed photothermographic material and developed. As a preferred embodiment of the heat developing machine to be used, as a type in which the photothermographic material is brought into contact with a heat source such as a heat roller or a heat drum, Japanese Patent Publication No. 5-56499, Japanese Patent Application Laid-Open Nos. 9-292695, 9-297385 and International The heat developing machine described in published WO 95/30934, and the thermal developing machine described in JP-A-7-13294, WO 97/28489, 97/28488 and 97/28487 as non-contact type types are disclosed. is there. A particularly preferred embodiment is a non-contact type heat developing machine. A preferred development temperature is 80 to 250 ° C, more preferably 100 to 140 ° C. The development time is preferably 1 to 180 seconds, more preferably 5 to 90 seconds. The line speed is preferably 140 cm / min or less.

  As a method for preventing processing unevenness due to dimensional change of the photothermographic material during heat development, the image is not heated at a temperature of 80 ° C. or higher and lower than 115 ° C., heated for 5 seconds or more, and then heated at 110 to 140 ° C. It is effective to adopt a method of developing and forming an image (so-called multistage heating method). When the photothermographic material is subjected to heat development processing, it is exposed to a high temperature of 110 ° C. or higher, and therefore, a part of the components contained in the material or a part of the decomposition components due to heat development is volatilized. These volatile components cause uneven development, corrode heat developing machine components, precipitate at low temperatures, cause deformation of the screen as a foreign object, 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 to optimally adjust the air flow in the heat developing machine. These methods can be used effectively in combination.

  International Publication Nos. WO95 / 30933, 97/21150, and JP-T-10-500496 have a first opening for introducing volatile components and a second opening for discharging, which have bound absorbent particles. It is described that the filter cartridge is used in a heating device that heats a photothermographic material in contact with the filter cartridge. In addition, International Publication No. WO96 / 12213 and JP-T-10-507403 describe the use of a filter in which a heat conductive condensing collector and a gas absorbing fine particle filter are combined. In the present invention, these can be preferably used. U.S. Pat. No. 4,518,845 and JP-B-3-54331 disclose a device for removing vapor from a photothermographic material, a pressure device for pressing the photothermographic material to a heat transfer member, and a heat transfer member. The structure which has the apparatus which heats is described. In addition, International Publication No. WO 98/27458 describes that a component that increases fogging from the photothermographic material is removed from the surface of the photothermographic material. These techniques can also be preferably used.

  FIG. 1 shows an example of the configuration of a heat developing machine used for heat development processing of the photothermographic material of the present invention. FIG. 1 is a side view of a heat developing machine. 1 is a pair of carry-in rollers 11 (the upper roller is a silicon rubber roller and the lower roller is an aluminum heat roller) that carries the photothermographic material 10 into a heating unit while correcting and preheating the photothermographic material 10 in a flat shape. An unloading roller pair 12 for unloading the photothermographic material 10 after heat development from the heating unit while correcting it to a flat shape is provided. The photothermographic material 10 is thermally developed while being conveyed from the carry-in roller pair 11 to the carry-out roller pair 12. The transporting means for transporting the photothermographic material 10 during the heat development is provided with a plurality of rollers 13 on the side where the surface having the image forming layer contacts, and on the side where the back surface on the opposite side contacts, a non-woven fabric (fragrance A smooth surface 14 on which a polyamide, a Teflon (registered trademark), or the like is bonded. The photothermographic material 10 is conveyed while the back surface is slid onto the smooth surface 14 by driving a plurality of rollers 13 that are in contact with the surface having the image forming layer. A heater 15 is installed above the roller 13 and below the smooth surface 14 so as to be heated from both sides of the photothermographic material 10. In this case, a plate heater or the like is used as the heating means. The clearance between the roller 13 and the smooth surface 14 varies depending on the member of the smooth surface, but is appropriately adjusted to a clearance that allows the photothermographic material 10 to be conveyed. Preferably it is 0-1 mm.

  The material of the surface of the roller 13 and the member of the smooth surface 14 may be anything as long as they have high temperature durability and do not interfere with the transport of the photothermographic material 10, but the material of the roller surface is silicon rubber, and the member of the smooth surface is aromatic. A non-woven fabric made of an aromatic polyamide or Teflon (registered trademark) is preferred. As the heating means, it is preferable to use a plurality of heaters and freely set the heating temperature.

  Further, a guide plate 16 is installed downstream of the heat development processing unit B, and a slow cooling unit C having the carry-out roller pair 12 and the guide plate 16 is installed. The guide plate 16 is preferably made of a material having a low thermal conductivity, and is preferably cooled gradually in order to prevent deformation of the photothermographic material 10, with a cooling rate of 0.5 to 10 ° C./second. Is preferred. As described above, the description has been given according to the illustrated example. However, the present invention is not limited to this, and the heat developing machine used in the present invention may have various configurations such as the one described in JP-A-7-13294. In the case of the multi-stage heating method preferably used in the present invention, two or more heat sources having different heating temperatures may be installed in the apparatus as described above and continuously heated at different temperatures.

  Hereinafter, the present invention will be described in detail with reference to examples, but the embodiment of the present invention is not limited thereto. Unless otherwise specified, “%” in the examples represents “mass%” and “part” represents “part by mass”.

Example 1
<Preparation of silver halide emulsion A>
After dissolving 11 g of alkali-treated gelatin (Ca 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 a temperature of 40 ° C., 159 ml of an aqueous solution containing 18.6 g of silver nitrate, 1 mol / L of potassium bromide, 5 × 10 ⁻⁶ mol / L of (NH ₄ ) ₂ RhCl ₅ · H ₂ O and 2 × 10 ⁻⁵ mol / L of K ₃ IrCl ₆ It was added over 6 minutes and 30 seconds by the control double jet method while keeping the water-containing L and pAg 7.7. Then, 28 minutes by the controlled double jet method while maintaining the solution 476ml of potassium bromide containing silver nitrate 55.5 g 1 mol / L and K ₃ IrCl ₆ to a 2 × 10 ^-5 mol / L include halogen salt solution to pAg7.7 Added over 30 seconds. Thereafter, the pH was lowered to cause coagulation sedimentation, and desalting was performed, and 51.1 g of low molecular weight gelatin having an average molecular weight of 15,000 (Ca content of 20 ppm or less) was added to adjust the pH to 5.9 and pAg 8.0. The obtained particles were cubic particles having an average particle 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, and after 3 minutes, 71 μmol of triethylthiourea was added, followed by ripening 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., 4.7 × 10 ⁻² mol of potassium bromide (added as an aqueous solution), 12.8 × 10 ⁻⁴ mol of the following sensitizing dye A (1 mol) per mol of silver halide. 6.4 × 10 ⁻³ mol of Compound B (added as a methanol solution) was added with stirring, and after 20 minutes, it was rapidly cooled to 30 ° C. to obtain a silver halide emulsion A.

<Preparation of silver behenate dispersion A>
Behenic acid (manufactured by Henkel: Edenor C22-85R) 87.6 kg, distilled water 423 liters, 5 mol / L sodium hydroxide aqueous solution 49.2 L, t-butyl alcohol 120 L were mixed and stirred at 75 ° C. for 1 hour to react. To obtain a sodium behenate solution. Separately, 206.2 L 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 t-butyl alcohol was kept at 30 ° C., and while stirring, the total amount of the previous sodium behenate solution and the total amount of the aqueous silver nitrate solution were kept constant at 62 minutes and 10 seconds, respectively. Added over 60 minutes. At this time, only the aqueous silver nitrate solution was added for 7 minutes and 20 seconds after the start of the addition of the aqueous silver nitrate solution, and then the addition of the sodium behenate solution was started. After the completion of the addition of the aqueous silver nitrate solution, only the sodium behenate solution was added. To be added. At this time, the temperature in the reaction vessel was set to 30 ° C., and the liquid temperature was controlled so as not to rise. The piping of the sodium behenate solution addition system was kept warm by steam tracing, and the amount of steam was adjusted so that the liquid temperature at the outlet of the addition nozzle tip was 75 ° C. Further, 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 silver nitrate aqueous solution were symmetrically arranged around the stirring axis, and were adjusted to a height that did not 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, and the temperature was lowered to 25 ° C. Thereafter, the solid content was separated by suction filtration, and the solid content was washed with water until the conductivity of the filtrate reached 30 μS / cm. The solid content thus obtained was stored as a wet cake without drying. When the morphology of the obtained silver behenate particles was evaluated by electron microscopic photography, it was a scaly crystal having an average projected area diameter of 0.52 μm, an average particle thickness of 0.14 μm, and an average sphere equivalent diameter variation coefficient of 15%. It was.

Next, a dispersion of silver behenate was prepared by the following method. 7.4 g of polyvinyl alcohol (Kuraray Co., Ltd .: PVA-217, average degree of polymerization: about 1700) and water are added to the wet cake equivalent to 100 g of the dry solid content to make the total amount 385 g, and then pre-dispersed with a homomixer did. Next, the pre-dispersed stock solution is treated 3 times by adjusting the pressure of a disperser (manufactured by Microfluidics International Corporation: Microfluidizer M-110S-EH, using G10Z interaction chamber) to 1750 kg / cm ^2. A silver behenate dispersion A was obtained. The cooling operation was set to a desired dispersion temperature by installing a serpentine heat exchanger before and after the interaction chamber and adjusting the temperature of the refrigerant. The silver behenate particles contained in the silver behenate dispersion A thus obtained were particles having a volume weighted average diameter of 0.52 μm and a coefficient of variation of 15%. The particle size was measured with Master Sizer X (Malvern Instruments Ltd.). Judging from the electron micrograph, the ratio of the long side to the short side was 1.5, the particle thickness was 0.14 μm, and the average aspect ratio (equivalent circle diameter of particle projected area / particle thickness) was 5.1. .

<Preparation of solid fine particle dispersion of reducing agent>
Surfynol 104E (10 kg of 20% aqueous solution of 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane and modified polyvinyl alcohol (Kuraray Co., Ltd .: Poval MP203) was added to 10 kg. (Nissin Chemical Co., Ltd.) (400 g), methanol (640 g) and water (16 kg) were added and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump and dispersed for 3 hours 30 minutes in a horizontal sand mill (imex: UVM-2) filled with zirconia beads having an average diameter of 0.5 mm, and then benzoisothiazolinone sodium salt 4 g and water were added to adjust the concentration of the reducing agent to 25% to obtain a solid fine particle dispersion of the reducing agent. The reducing agent particles contained in the dispersion thus obtained had an average particle size of 0.44 μm, a maximum particle size of 2.0 μm or less, and an average particle size variation coefficient 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 solid fine particle dispersion of polyhalogen compound A>
10 kg of polyhalogen compound A [tribromomethyl (4- (2,4,6-trimethylphenylsulfonyl) phenyl) sulfone], 10 kg of 20% aqueous solution of modified polyvinyl alcohol (Poval MP203: supra), tri-i- 639 g of a 20% aqueous solution of sodium propylnaphthalenesulfonate, 400 g of Surfynol 104E (supra), 640 g of methanol and 16 kg of water were added and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump, dispersed in a horizontal sand mill (UVM-2: supra) filled with zirconia beads having an average diameter of 0.5 mm for 5 hours, and then water was added to increase the concentration of polyhalogen compound A. The solid fine particle dispersion of polyhalogen compound A was obtained by adjusting to 25%. The polyhalogen compound particles contained in the dispersion thus obtained had an average particle 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 solid fine particle dispersion of polyhalogen compound B>
5 kg of polyhalogen compound B (tribromomethylnaphthylsulfone), 2.5 kg of 20% aqueous solution of modified polyvinyl alcohol (Poval MP203: supra), 213 g of 20% aqueous solution of sodium tri-i-propylnaphthalenesulfonate, and 10 kg of water Was added and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump, dispersed in a horizontal sand mill (UVM-2: supra) filled with zirconia beads having an average diameter of 0.5 mm for 5 hours, and then 2.5 g of benzoisothiazolinone sodium salt and Water was added to adjust the concentration of polyhalogen compound B to 23.5% to obtain a solid fine particle dispersion of polyhalogen compound B. The organic polyhalogen compound particles contained in the dispersion thus obtained had an average particle size of 0.38 μm, a maximum particle size of 2.0 μm or less, and an average particle size 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 aqueous solution of polyhalogen compound C>
The preparation recipe (per 100 ml finished) and the preparation procedure are as follows.

(A) Water 75.0ml
(B) 8.6 ml of 20% aqueous solution of sodium tripropylnaphthalenesulfonate
(C) 5% aqueous solution of sodium dihydrogen orthophosphate dihydrate 6.8 ml
(D) 1 mol / L aqueous solution of potassium hydroxide 9.5 ml
(E) Polyhalogen compound C (3-tribromomethanesulfonylbenzoylaminoacetic acid) 4.0 g
1. While stirring at room temperature, (a) to (d) were sequentially added, and after completion of the addition of (d), the mixture was stirred for 5 minutes.
2. Furthermore, the powder of (e) was added with stirring, and the solution was uniformly dissolved until the solution became transparent.
3. The obtained aqueous solution was filtered through a 200-mesh polyester screen to remove foreign substances such as dust and stored.

<Preparation of emulsified dispersion of compound Z>
10 kg of R-054 (manufactured by Sanko) containing 85% of compound Z and 11.66 kg of MIBK (methyl-i-butylketone) were mixed and then purged with nitrogen and dissolved at 80 ° C. for 1 hour. 25.52 kg of water, 12.76 kg of a 20% aqueous solution of MP polymer (manufactured by Kuraray Co., Ltd .: MP-203) and 0.44 kg of a 20% aqueous solution of sodium tri-i-propylnaphthalenesulfonate were added to this solution, The emulsion was emulsified and dispersed at 3,600 rpm for 60 minutes while maintaining 40 ° C. Further, 0.08 kg of Surfinol 104E (supra) and 47.94 kg of water were added to this solution and distilled under reduced pressure to remove MIBK, and then the concentration of Compound Z was adjusted to 10%. The particles of Compound Z contained in the dispersion thus obtained had an average particle size of 0.19 μm, a maximum particle size of 1.5 μm or less, and a particle size variation coefficient of 17%. 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 colorant dispersion>
The preparation recipe (per 100 g finished) and the preparation procedure are as follows.

(1) 62.35 g of water
(2) Modified polyvinyl alcohol (Poval MP203: supra) 2.0 g
(3) 10% aqueous solution of polyvinyl alcohol (Kuraray Co., Ltd .: PVA-217)
25.5g
(4) Sodium tripropylnaphthalenesulfonate 20% aqueous solution 3.0 g
(5) 6-i-propylphthalazine (70% aqueous solution) 7.15 g
1. While stirring (1) at room temperature, (2) was added so as not to be agglomerated and stirred and mixed for 10 minutes.
2. Thereafter, the mixture was heated and heated up until the internal temperature reached 50 ° C., and then stirred for 90 minutes in the range of the internal temperature of 50 to 60 ° C. to be uniformly dissolved.
3. The internal temperature was lowered to 40 ° C. or lower, (3), (4) and (5) were added, and the mixture was stirred for 30 minutes to obtain a transparent dispersion.
4). 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 nucleating agent>
1 kg of polyvinyl alcohol (PVA-217: supra) and 36 kg of water were added to 4 kg of the nucleating agent described in Table 1, and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump and dispersed in a horizontal sand mill (UVM-2: supra) filled with zirconia beads having an average diameter of 0.5 mm for 12 hours, and then 4 g of benzoisothiazolinone sodium salt and water were added. In addition, the nucleating agent concentration was adjusted to 10% to obtain a solid fine particle dispersion of the nucleating agent. The nucleating agent particles contained in the dispersion thus obtained had an average particle size of 0.34 μm, a maximum particle size of 3.0 μm or less, and a coefficient of variation 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 solid fine particle dispersion of development accelerator A>
10 kg of development accelerator A, 10 kg of 20% aqueous solution of modified polyvinyl alcohol (Poval MP203: supra) and 20 kg of water were added and mixed well to obtain a slurry. The slurry was fed with a diaphragm pump, dispersed in a horizontal sand mill (UVM-2: supra) filled with zirconia beads having an average diameter of 0.5 mm for 5 hours, and then water was added to increase the concentration of the development accelerator A. The dispersion was adjusted to 20% to obtain a solid fine particle dispersion of development accelerator A. The development accelerator particles contained in the dispersion thus obtained had an average particle size of 0.5 μm, a maximum particle size of 2.0 μm or less, and an average particle size 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 image forming layer coating solution>
The following binder, additive and silver halide emulsion A were added to 1 mol of silver of the silver behenate dispersion A prepared previously, and water was added to prepare an image forming layer coating solution. After the preparation, vacuum deaeration was performed at a pressure of 0.54 atm for 45 minutes. The coating solution had a pH of 7.7 and a viscosity of 50 mPa · s at 25 ° C.

Binder: Rack Star 3307B (Dainippon Ink & Chemicals, Inc .: SBR Latex, Tg 17 ° C.) 397 g as solid content
1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethyl hexane (reducing agent) 149.5 g as a solid content
Polyhalogen compound B 36.3 g as solid content
Polyhalogen compound C 2.34 g as solid content
Sodium ethylthiosulfonate 0.47g
Benzotriazole 1.02g
6-i-propylphthalazine (coloring agent) 15.0 g
Compound Z 9.7g as solid content
Nucleating agents listed in Table 1 Amounts listed in Table 1 Dye A (added as a mixture with low molecular weight gelatin having an average molecular weight of 15,000, 783
The coating amount at which the optical density of nm is 0.3) As a guideline, the solid content is 0.40 g.
Silver halide emulsion A 0.06 mol as Ag amount Compound A (preservative) 40 ppm in coating solution (2.5 mg / m ² as coating amount)
The total solvent amount in the methanol coating solution was 1%, and the total solvent amount in the ethanol coating solution was 2%. The Tg of the coating film was 17 ° C.

<Preparation of protective layer coating solution>
Polymer latex solution of methyl methacrylate / styrene / 2-ethylhexyl acrylate / 2-hydroxyethyl methacrylate / acrylic acid (58.9 / 8.6 / 25.4 / 5.1 / 2% ratio) (Tg 46 ° C. as copolymer) (Calculated value), 21.5% as the solid content concentration), 100 ppm of compound A, and further 15% of compound D as the film-forming aid with respect to the solid content of the latex, and the Tg of the coating solution being 24 ° C. 943 g of water having a mean particle diameter of 116 nm), 1.62 g of compound E, 114.8 g of an aqueous solution of polyhalogen compound C, 17.0 g of polyhalogen compound A as a solid content, sodium dihydrogen orthophosphate -0.69 g of dihydrate as solid content, 11.55 g of development accelerator A as solid content, matting agent (polystyrene particles, average 7 μm diameter, coefficient of variation of average particle size 8%) 1.58 g and polyvinyl alcohol (Kuraray Co., Ltd .: PVA-235) 29.3 g are added, and water is further added to the coating solution (containing 0.8% methanol solvent). Was prepared. After completion, vacuum degassing was performed at a pressure of 47.6 kPa for 60 minutes. The coating solution had a pH of 5.5 and a viscosity of 45 mPa · s at 25 ° C.

<Preparation of lower overcoat 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, compound A of 100 ppm is contained, and further, a compound D as a film-forming aid is incorporated by 15% by mass with respect to the solid content of the latex. Water was added to 625 g of glass transition temperature of 24 ° C., average particle diameter 74 nm), 0.23 g of compound C, 0.13 g of compound E, 11.7 g of compound F, 2.7 g of compound H and polyvinyl. 11.5 g of alcohol (PVA-235: supra) was added, and water was further added to prepare a coating solution (containing 0.1% methanol solvent). After completion, vacuum degassing was performed at a pressure of 47.6 kPa for 60 minutes. The coating solution had a pH of 2.6 and a viscosity of 30 mPa · s at 25 ° C.

<Preparation of coating solution for upper overcoat layer>
Polymer latex solution of methyl methacrylate / styrene / 2-ethylhexyl acrylate / 2-hydroxyethyl methacrylate / acrylic acid (58.9 / 8.6 / 25.4 / 5.1 / 2% ratio) (Tg 46 ° C. as copolymer) (Calculated value), 21.5% as the solid content concentration, 100 ppm of compound A, and further 15% of compound D as a film-forming aid with respect to the solid content of the latex, and Tg of the coating solution as 24 ° C. 1) of Carnava wax (manufactured by Chukyo Yushi Co., Ltd .: cellosol 524, less than 5 ppm as silicone content) 30% solution 18.4 g, compound C 0.23 g, compound E 1.85 g, Compound G 1.0 g, matting agent (polystyrene particles, average particle diameter 7 μm, average particle diameter variation coefficient 8%) 3. 5g and polyvinyl alcohol (PVA-235: supra) 26.5 g was added thereto to prepare further coating solution was added to water (a methanol solvent 1.1% containing). After the preparation, vacuum degassing was performed at a pressure of 47.6 kPa for 60 minutes. The coating solution had a pH of 5.3 and a viscosity of 25 mPa · s at 25 ° C.

<Preparation of PET support with back layer / undercoat layer>
It was produced by the following procedure.

(PET support)
Using terephthalic acid and ethylene glycol, polyethylene terephthalate 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. After pelletizing this, it was dried at 130 ° C. for 4 hours, melted at 300 ° C., extruded from a T-die, and then rapidly cooled to produce an unstretched film having a thickness such that the film thickness after heat setting was 120 μm. did. This was stretched 3.3 times in the longitudinal direction using rolls having different peripheral speeds, and then stretched 4.5 times in the 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. After that, after slitting the chuck portion of the tenter, both ends were knurled and wound at 4.8 kg / cm ² . Thus, a roll-shaped PET support having a width of 2.4 m, a length of 3500 m, and a thickness of 120 μm was obtained.

(Coating of undercoat layer and back layer)
(1) Undercoat first layer After subjecting the PET support to a corona discharge treatment of 0.375 kV · A · min / m ² , a coating solution having the composition shown below is supported to 6.2 ml / m ^2. It was applied on the body and dried at 125 ° C. for 30 seconds, 150 ° C. for 30 seconds, and 185 ° C. for 30 seconds.

Latex A 280g
Potassium hydroxide 0.5g
Polystyrene fine particles (average particle diameter: 2 μm, average particle diameter variation coefficient 7%) 0.03 g
1.8 g of 2,4-dichloro-6-hydroxy-s-triazine
Compound Bc-C 0.097g
(2) Undercoat second layer A coating solution having the composition shown below was applied onto the first undercoat layer so as to be 5.5 ml / m ^2, and at 125 ° C. for 30 seconds, Drying was performed at 150 ° C. for 30 seconds and at 170 ° C. for 30 seconds.

Deionized gelatin (Ca ²⁺ content 0.6 ppm, jelly strength 230 g) 10 g
Acetic acid (20% aqueous solution) 10g
Compound Bc-A 0.04 g
25 g of methylcellulose (2% aqueous solution)
Polyethyleneoxy compound 0.3g
Distilled water Total amount of 1,000 g (3) Back first layer Corona discharge treatment of 0.375 kV · A · min / m ² is applied to the surface opposite to the surface of the undercoat layer applied to the surface. A coating solution having the composition shown below was applied to 13.8 ml / m ² and dried at 125 ° C. for 30 seconds, 150 ° C. for 30 seconds, and 185 ° C. for 30 seconds.

Jurimer ET410 (30% aqueous dispersion: manufactured by Nippon Pure Chemical Co., Ltd.) 23g
4.44 g of alkali-treated gelatin (molecular weight about 10,000, Ca ²⁺ content 30 ppm)
Deionized gelatin (Ca ²⁺ content 0.6ppm) 0.84g
Compound Bc-A 0.02 g
Dye Bc-A (adjusted so that the optical density at 783 nm is 1.3 to 1.4)
0.88g as a guide
Polyoxyethylene phenyl ether 1.7g
15% of an 8% aqueous solution of a water-soluble melamine compound (Sumitomo Chemical Co., Ltd .: Sumtex Resin M-3)
FS-10D (aqueous dispersion of needle-like particles of Sb-doped tin oxide: manufactured by Ishihara Sangyo Co., Ltd.) 24 g
Polystyrene fine particles (average particle size 2 μm, average particle size variation coefficient 7%) 0.03 g
Distilled water Total amount of 1,000 g (4) Back second layer A coating solution having the composition shown below was applied onto the back first layer so as to be 5.5 ml / m ^2, and then at 125 ° C. for 30 seconds. And dried at 150 ° C. for 30 seconds and 170 ° C. for 30 seconds.

Jurimer ET410 (30% aqueous dispersion: supra) 57.5g
Polyoxyethylene phenyl ether 1.7g
8% aqueous solution of water-soluble melamine compound (Smitex Resin M-3: supra) 5g
Cerosol 524 (30% aqueous solution: manufactured by Chukyo Yushi Co., Ltd.) 6.6 g
(5) Back third layer Apply the same coating solution as the undercoat first layer onto the back second layer so as to be 6.2 ml / m ^2, and add 30 ml at 125 ° C. Second, 150 ° C. for 30 seconds, and 185 ° C. for 30 seconds.

(6) Back Fourth Layer A coating solution having the composition shown below was applied onto the third back layer so as to be 13.8 ml / m ^2, and was 30 seconds at 125 ° C., 30 seconds at 150 ° C., and 30 seconds at 170 ° C. Dried for 2 seconds.

Latex B 286g
Compound Bc-B 2.7 g
Compound Bc-C 0.6g
Compound Bc-D 0.5g
2,4dichloro-6-hydroxy-s-triazine 2.5 g
Polymethylmethacrylate (10% aqueous dispersion, average particle size 5 μm, average particle variation coefficient 7%) 7.7 g
Distilled water Amount that totals 1,000 g

Latex A: Core-shell type latex with 90% core portion and 10% shell portion, core portion: vinylidene chloride / methyl acrylate / methyl methacrylate / acrylonitrile / acrylic acid (93/3/3 / 0.9 / 0.1%) , Shell part: Vinylidene chloride / methyl acrylate / methyl methacrylate / acrylonitrile / acrylic acid (88/3/3/3/3% ratio), weight average molecular weight 38,000
Latex B: Methyl methacrylate / styrene / 2-ethylhexyl acrylate / 2-hydroxyethyl methacrylate / acrylic acid (59/9/26/5/1% ratio) copolymer Bc-B: C ₁₈ H ₃₇ OSO ₃ Na
_{Bc-C: C 8 F 17} SO 3 Li
_{Bc-D: C 8 F 17} SO 2 N (C 4 H 9) (CH 2 CH 2 O) 4 (CH 2) 4 SO 3 Na
<Transport heat treatment>
The PET support with the back / undercoat layer thus prepared was placed in a heat treatment zone having a total length of 200 m set at 160 ° C. and conveyed at a tension of 2 kg / cm ² and a conveyance speed of 20 m / min. Subsequent to this heat treatment, the film was passed through a 40 ° C. zone for 15 seconds, followed by post-heat treatment and winding. The winding tension at this time was 10 kg / cm ² .

<Preparation of photothermographic material>
Using the slide beat coating method disclosed in FIG. 1 of JP-A-2000-2964 on the undercoat layer of the PET support on the side on which the undercoat first layer and the undercoat second layer have been applied, the image described above is used. The forming layer coating solution was applied so that the amount of silver applied was 1.5 g / m ² . Furthermore, the protective layer coating solution was applied simultaneously with the image forming layer coating solution so that the solid content coating amount of the polymer latex was 1.29 g / m ² . Thereafter, the lower layer overcoat layer coating solution is coated on the protective layer with a polymer latex solids coating amount of 1.97 g / m ² and the upper layer overcoat layer coating solution is coated with a polymer latex solids coating amount of 1.07 g / m ^2. A photothermographic material was prepared by simultaneously applying multiple layers together with the lower overcoat coating solution so as to be m ² .

  The drying at the time of coating is performed in the horizontal drying zone (coating machine) until the drying point where the flow of the coating liquid almost disappears in the range of the dew point of 14 to 25 ° C. and the liquid film surface temperature of 35 to 40 ° C. The support was carried out at an angle of 1.5 to 3 ° with respect to the horizontal direction. Winding after drying is performed under conditions of 23 ± 5 ° C. and 45 ± 5% RH (relative humidity), and the winding shape is adjusted to the subsequent processing mode (image forming layer side outer winding), and the image forming layer side is I was outside. The packaged humidity of the photosensitive material is 20 to 40% RH (measured at 25 ° C.), the film surface pH of the obtained photothermographic material on the image forming layer side is 5.0, and the Beck smoothness is 850 seconds. The film surface pH on the opposite side was 5.9, and the Beck smoothness was 560 seconds.

<Image formation and evaluation>
The obtained photothermographic material was used a single channel cylindrical inner surface type laser exposure apparatus equipped with a semiconductor laser having a beam diameter (FWHM ½ of the beam intensity) of 12.56 μm, a laser output of 50 mW, and an output wavelength of 783 nm. Then, exposure was performed at a mirror rotational speed of 60,000 rpm and an exposure time of 1.2 × 10 ⁻⁸ seconds. The overlap coefficient at this time was 0.449, and the laser energy density on the surface of the photothermographic material was 75 μJ / cm ² .

  Using the above laser exposure apparatus, the test step is output while changing the amount of light at 175 lines / 2.54 cm, the following heat development processing is performed, and Dmax when exposed at an LV value at which the halftone dot is 50% The (highest concentration) part was measured and used as the practical concentration.

《Humidity dependency》
A photothermographic material left for 16 hours in an environment of 25 ° C. and 80% RH was subjected to a heat development treatment by performing a 60 μm line width exposure under the above conditions, and in an environment of 25 ° C. and 10% RH. When the photothermographic material left for 16 hours was similarly exposed and heat-developed in the environment, the line width, Dmin (fogging), and Dmax (maximum density) were evaluated. Density measurement was performed with a Macbeth TD904 densitometer (visible density). The line width variation was calculated by the following formula.

Line width variation = Line width (25 ° C, 80% RH)-Line width (25 ° C, 10% RH)
《Image defect》
The image defect was visually judged about the sample used for the said humidity dependence evaluation.

5: No image defect per loupe field of view 4: 1-2 image defects per loupe field of view 3: 3-5 image defects per loupe field of view 2: Image defects 6-10 per loupe field of view Available 1: There are 11 or more image defects per loupe field of view (thermal development)
The exposed photothermographic material was heat developed using the heat developing machine shown in FIG. The roller surface material of the heat development processing part was made of silicon rubber, the smooth surface was made of Teflon (registered trademark) nonwoven fabric, and the conveying line speed was set to 150 cm / min. The heat development processing was carried out at 120 ° C. (photothermographic material surface temperature) at 17.2 seconds and at a slow cooling portion of 13.6 seconds. The temperature accuracy in the width direction was ± 0.5 ° C. Each roller temperature was set to be 5 cm longer on both sides than the width of the photothermographic material (for example, 61 cm in width), and the temperature was also applied to that portion so that temperature accuracy was obtained. Since both ends of each roller are drastically lowered in temperature, the portion 5 cm longer than the width of the photothermographic material is set so that the temperature is 1 to 3 ° C. higher than the center of the roller. Care was taken to ensure that the image density (e.g. within a width of 61 cm) was a uniform finish. Table 1 shows the results of the above evaluation for each photothermographic material.

  As is clear from the results in Table 1, sample No. 1-5 to 1-14 show that stable Dmin and Dmax are obtained even in a low-humidity environment and a high-humidity environment, and the occurrence frequency of image defects is low, and it has excellent performance.

Example 2
Sample No. 1 prepared in Example 1 was used. Evaluation similar to Example 1 except that 1-1 to 1-14 are heat-developed using a heat developing machine having a pre-heating part in front of the heat-developing part and setting the temperature of the pre-heating part to 100 ° C. Went. As a result, similar to the result of Example 1, the present sample No. 1-5 to 1-14 gave good results.

FIG. 2 is a side view showing a configuration example of a heat developing machine preferably used when developing the photothermographic material of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Photothermographic material 11 Carry-in roller pair 12 Carry-out roller pair 13 Roller 14 Smooth surface 15 Heating heater 16 Guide plate A Preheating part B Thermal development processing part C Slow cooling part

Claims (2)

A photothermographic material having an image forming layer containing a non-photosensitive organic silver salt, a reducing agent, a photosensitive silver halide, a high contrast agent and a binder and a non-photosensitive layer protecting the image forming layer on a support. In the above, the contrast enhancing agent is a compound represented by the following general formula (1), and the adhesive strength between the image forming layer and the non-photosensitive layer after heat development is 90 N / m or more. Photothermographic material.

[Wherein, R ₁ represents an alkyl group, an aryl group or a heterocyclic group, R ₂ represents an alkoxy group, an aryloxy group or an alkylamino group, and M represents a cation other than a hydrogen cation. ] The photothermographic material according to claim 1, wherein the photothermographic material is processed by an automatic heat developing machine having a preheating portion in front of the heat developing portion and having a temperature of 80 to 120 ° C. Method.

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