JP2006091635A - Heat developable photosensitive material and image forming method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat developable photosensitive material having ultrahigh contrast, low fog, stability to variation in development temperature and large latitude to variation in development conditions as a material for a scanner or an image setter for printing plate making, and to provide an image forming method using the same. <P>SOLUTION: In the heat developable photosensitive material having on a support at least one image forming layer containing a non-photosensitive organic silver salt, a reducing agent for the non-photosensitive organic silver salt, a photosensitive silver halide, a contrast enhancer and a binder, and at least one non-photosensitive layer for protecting the image forming layer, the contrast enhancer is a compound represented by formula (1) and a pH of a surface of the image forming layer is 5.3-7.0. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photothermographic material and an image forming method, and particularly to image formation suitable for printing plate making using a photothermographic material containing an organic silver salt, a silver halide, a binder and a reducing agent on a support. It is about the method. More specifically, the present invention relates to a photothermographic material having ultra-high contrast, low fog, low temperature dependency during heat development processing, and a wide latitude with respect to fluctuations in heat development conditions, and an image forming method using the same.

  Many photosensitive materials having a photosensitive layer on a support and forming an image by image exposure are known. Among them, there is a technique for forming an image by thermal development as a system that contributes to environmental conservation and can simplify the image forming means.

  In recent years, in the photoengraving field, reduction of processing waste liquid is strongly desired from the viewpoint of environmental protection and space saving.

  Therefore, there is a technology relating to a photothermographic material for photoengraving that can be efficiently exposed by a laser scanner or a laser image setter and can form a clear black image having high resolution and sharpness. is needed.

  According to such a photothermographic material, it is possible to supply a photothermographic processing system that does not require solution processing chemicals and that is simpler and does not impair the environment.

  For example, US Pat. Nos. 3,152,904 and 3,457,075 and D.W. “Thermally Processed Silver Systems,” Imaging Processes and Materials, 8th edition, J. Sturge, St. Wall, by Klosterboer. (Walworth, A. Shepp, Vol. 9, 279, 1989).

  Such a photothermographic material usually contains a reducible non-photosensitive silver salt (eg, organic silver salt), a catalytically active amount of a photocatalyst (eg, silver halide), and a silver reducing agent, usually dispersed in an organic binder matrix. Contained in the state.

  The photosensitive material is stable at normal temperature, but when heated to a high temperature (for example, 80 ° C. or higher) after exposure, the silver is obtained through a redox reaction between a reducible silver source (which functions as an oxidizing agent) and the 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 areas turns black and forms an image in contrast to the unexposed areas.

Patent Documents 1 to 7 and the like disclose a super high contrast photothermographic material containing a high contrast agent. However, in these photothermographic materials, there is a problem that sensitivity, Dmax, and line width largely fluctuate due to temperature fluctuations in the development environment, and improvement has been desired.
US Pat. No. 5,496,695 US Pat. No. 5,545,515 US Pat. No. 5,654,130 US Pat. No. 5,705,324 JP 11-119372 A JP-A-11-109546 Japanese Patent Laid-Open No. 11-231459

  The object of the present invention has been made in view of the above circumstances, and particularly for printing plate-making scanners and imagesetters, is ultra-high contrast, low fog, and stable with respect to fluctuations in development temperature. It is an object of the present invention to provide a photothermographic material having a wide latitude against fluctuations and an image forming method using the same.

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

(Claim 1)
An image forming layer containing a non-photosensitive organic silver salt, a reducing agent of the non-photosensitive organic silver salt, a photosensitive silver halide, a contrast increasing agent and a binder on a support, and a non-photosensitive layer for protecting the image forming layer In each of the photothermographic materials having at least one layer, the contrast-enhancing agent is a compound represented by the following general formula (1), and the pH of the film surface of the image forming layer is 5.3 to 7.0. A photothermographic material characterized by the above.

[Wherein, X represents an alkoxy group, an aryloxy group, an amino group, or an alkylamino group, Y represents an alkyl group, an aryl group, or a heterocyclic group, and M represents a cation other than a hydrogen ion. ]
(Claim 2)
The photothermographic material according to claim 1, wherein the photothermographic material is processed using a heat development automatic developing machine having a preheating part in front of the heat developing part and having a temperature of 80 to 120 ° C. Image forming method.

  According to the present invention, a photothermographic material having super high contrast, low fog, stable with respect to fluctuations in development temperature, and a wide latitude with respect to fluctuations in development conditions, and an image forming method using the same are obtained.

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

  The photothermographic material of the present invention and an image forming method using the same will be described in detail below.

<< Compound Represented by Formula (1) >>
In the general formula (1), X represents an alkoxy group (preferably a substituted or unsubstituted alkoxy group having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 10 carbon atoms, such as methoxy. , Ethoxy, propoxy, isopropoxy, tert-butoxy, n-octyloxy, 2-methoxyethoxy and the like, and aryloxy groups (preferably having 6 to 30 carbon atoms, more preferably having 6 to 20 carbon atoms, particularly preferably Is a substituted or unsubstituted aryloxy group having 6 to 10 carbon atoms, such as phenoxy, 4-methylphenoxy, 4-tert-butylphenoxy, 4-methoxyphenoxy, 4-dimethylaminophenoxy, etc.), unsubstituted Amino group or alkylamino group (preferably having 1 to 30 carbon atoms, more preferably carbon number) -20, particularly preferably a substituted or unsubstituted alkylamino group having 1 to 10 carbon atoms, including saturated cyclic groups such as methylamino, ethylamino, dimethylamino, diethylamino, pyrrolidino, formolino, 2-hydroxy Each group of ethylamino, 2-methoxyethylamino, and bis (2-methoxyethyl) amino).

  X is preferably an alkoxy group or an alkylamino group.

  In the general formula (1), examples of the substituent for the alkoxy group and aryloxy group include an alkyl group (including a cycloalkyl group and a bicycloalkyl group), an alkenyl group (including a cycloalkenyl group and a bicycloalkyl group), and alkynyl. Group, 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, aryloxy Carbonyloxy group, amino group (including anilino group), acylamino group, aminocarbonylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfamoylamino group, alkyl and arylsulfonylamino group, mercapto Alkylthio group, arylthio 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.

  In general formula (1), Y represents a substituted or unsubstituted alkyl group which is linear, branched, cyclic, or a combination thereof.

  The alkyl group is preferably an alkyl group having 1 to 30 carbon atoms such as methyl, ethyl, n-propyl, isobutyl, tert-butyl n-octyl, eicosyl, 2-chloroethyl, 2-cyanoethyl, 2-ethylhexyl and the like. Each group is mentioned.

  Preferred examples of the cycloalkyl group include substituted or unsubstituted cycloalkyl groups having 3 to 30 carbon atoms such as cyclohexyl, cyclopentyl, 4-n-dodecylcyclohexyl and the like.

  The bicycloalkyl group is preferably a substituted or unsubstituted bicycloalkyl group having 5 to 30 carbon atoms, that is, a monovalent group obtained by removing one hydrogen atom from a bicycloalkane having 5 to 30 carbon atoms, for example, bicyclo [1,2,2heptan-2-yl, bicyclo [2,2,2he] octane-3-yl and the like. Further, it includes a tricyclo structure having many ring structures.

  Among the substituents described below, an alkyl group (for example, an alkyl group of an alkylthio group) also represents such an alkyl group.

  In general formula (1), Y is an aryl group, preferably a substituted or unsubstituted aryl group having 6 to 50 carbon atoms (for example, phenyl, p-tolyl, naphthyl, m-chlorophenyl, o-hexadecanoylamino). Each group such as phenyl), or a heterocyclic group (preferably a monovalent group obtained by removing one hydrogen atom from a 5- or 6-membered substituted or unsubstituted aromatic or non-aromatic heterocyclic compound). And more preferably a 5- or 6-membered aromatic heterocycle having 3 to 50 carbon atoms (for example, a ring such as 2-furyl, 2-thienyl, 2-pyrimidinyl, 2-benzothiazolyl, etc.). In general formula (1), Y is preferably an aryl group.

  Examples of the substituent for the alkyl group, aryl group, and heterocyclic group represented by Y include the same groups as those described above for X, but the most preferable substituent is an acylamino group having 8 to 50 carbon atoms, An aminocarbonylamino group and an alkoxycarbonylamino group.

  In the general formula (1), M represents a cation other than a hydrogen ion, that is, a counter cation of an oxygen anion. Examples of the cation other than the hydrogen ion include sodium, potassium, magnesium, calcium, zinc, silver, and quaternary ammonium. (For example, tetrabutylammonium, benzyltrimethylammonium, etc.). In the general formula (1), M is preferably sodium, potassium, zinc or quaternary ammonium.

  Specific examples of the compound represented by the general formula (1) used in the present invention are shown below, but the present invention is not limited thereto.

  The compound represented by the general formula (1) of the present invention can be easily obtained by synthesizing a 5-pyrazolone compound by a known method, formylating with a Vilsmeier reagent, and then treating under alkaline conditions. Specific synthesis examples are shown below.

(Synthesis of Compound 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.

  45 g of 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 to obtain 150 g of intermediate (A).

  A mixture of 100 g of the obtained intermediate (A), 160 g of reduced iron, 800 ml of isopropyl alcohol, 80 ml of water and 2 g of ammonium chloride was heated to reflux for 2 hours. The insoluble material was filtered while hot, 50 ml of concentrated hydrochloric acid was added to the filtrate, and the solvent was removed 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 g of dimethylacetamide, and 27 g of isopalmitic acid chloride was slowly added dropwise with ice cooling. After stirring for 30 minutes, 150 ml of dilute hydrochloric acid was added, and the precipitated crystals were filtered and recrystallized from acetonitrile to obtain 35 g of Intermediate (C) WO. 35 g of the obtained intermediate (C) was dissolved in 170 ml of DMF, and 11 ml of dimethylformamide dimethyl acetal was added at room temperature. The precipitated crystals were filtered to obtain 25 g of intermediate (D).

  16 g of the 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, and then 50 ml of 20% brine was added. The precipitated crystals were filtered and sufficiently washed with water to obtain 14 g of Compound Example A-4.

  The structures of intermediate (A), intermediate (B), intermediate (C), and intermediate (D) are shown below.

  The compound represented by the general formula (1) of 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. And dissolved in methyl cellosolve.

  In addition, it is dissolved by using a well-known emulsion 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 cyclohexane, 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 an ultrasonic wave by a method known as a solid dispersion method.

  The compound represented by the general formula (1) of the present invention may be added to any layer on the image forming layer side with respect to the support, but it should be added to a layer containing a silver salt or a layer adjacent thereto. Is preferred.

The addition amount of the general formula (1) compounds represented by the present invention depends on the type of photographically useful groups, per mol of silver 1 × 10 ^-6 to 1 mol are preferred, 1 × 10 ^-5 ~ 5 × 10 ⁻¹ mol is more preferable, and 2 × 10 ⁻⁵ to 2 × 10 ⁻¹ mol is most preferable. Only 1 type may be used for the compound represented by these General formula (1), and 2 or more types may be used together.

(Organic silver salt)
The photothermographic material of the present invention contains an organic silver salt as a reducible silver salt. The organic silver salt that can be used in the present invention is relatively stable to light, but is 80 ° C. or higher in the presence of an exposed photocatalyst (such as a latent image of photosensitive silver halide) and a reducing agent. When heated above, it is 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. Moreover, the complex of the organic or inorganic silver salt in which the ligand has a complex stability constant in the range of 4.0 to 10.0 is preferable.

  The silver-providing substance can preferably constitute about 5 to 70% by weight of the image forming layer. 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 fumaric acid. Including silver, silver tartrate, silver linoleate, silver butyrate or silver camphorate or mixtures thereof.

  In the present invention, among the organic acid silver or the organic acid silver mixture, it is preferable to use an organic acid silver having a silver behenate content of 75 mol% or more, and an organic acid silver having a silver behenate content of 85 mol% or more. More preferably, is used. Here, the silver behenate content is shown by molar fractionation of silver behenate with respect to the organic acid silver used.

  As the organic acid silver other than silver behenate contained in the organic acid silver used in the present invention, those mentioned above can be preferably used.

  The organic acid silver that can be used in the present invention is prepared by reacting a solution or suspension of an alkali metal salt (Na salt, K salt, Li salt, etc.) of the organic acid with silver nitrate. Regarding these preparation methods, the methods described in paragraphs [0019] to [0021] of JP-A No. 2000-292882 can be used.

  In the present invention, a method of preparing an organic acid silver by adding an aqueous silver nitrate solution and an organic alkali metal solution into a means for mixing a sealed liquid can be preferably used.

  Specifically, the method described in JP2001-033907 can be used.

  In the present invention, a silver nitrate aqueous solution and an organic alkali metal salt solution, or a water-soluble decomposition agent can be added to the reaction when preparing the organic acid silver. About the kind and usage-amount of the decomposition agent used here, it describes in the paragraph [0052] of Unexamined-Japanese-Patent No. 2000-305214.

  The organic acid silver used in the present invention is preferably prepared in the presence of a tertiary alcohol. As an example of the tertiary alcohol, a compound having 15 or less carbon atoms is preferable, and a compound having 10 or less carbon atoms is particularly preferable. Examples of preferable tertiary alcohols include tert-butanol, but the tertiary alcohol that can be preferably used in the present invention is not limited thereto.

  The addition time of the tertiary alcohol that can be preferably used in the present invention 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 alkali metal to dissolve and use the organic 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 [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 measuring method, for example, an organic silver salt dispersed in a liquid is irradiated with laser light, and a particle size (volume weighted average diameter) obtained by obtaining an autocorrelation coefficient with respect to temporal change of fluctuation of the scattered light. Can be obtained from

  The 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 used in the present invention is preferably desalted. The desalting method is not particularly limited, and known filtration methods such as centrifugal filtration, suction filtration, ultrafiltration, and water for block formation by agglomeration method can be preferably used.

  Regarding the ultrafiltration method, the method described in JP-A-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, it contains an organic silver salt as an image forming medium and is substantially free of photosensitive silver. It is preferable to use a dispersion method in which the water dispersion is converted to a high flow rate and then the pressure is reduced.

  For these methods, the methods described in paragraphs [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 used in the present invention is preferably monodispersed. Specifically, the percentage (variation coefficient) of the value obtained by dividing the standard deviation of the volume weighted average diameter by the volume weighted average diameter is 80% or less, more preferably 50% or less, and even more preferably 30% or less.

  The organic silver salt solid fine particle dispersion used in the present invention comprises at least an organic silver salt and water. The ratio of the organic silver salt to water is not particularly limited, but the ratio of the organic silver salt to the entire organic silver salt is preferably 5 to 50% by mass, and particularly preferably 10 to 30% by mass.

  It is preferable to use the above-mentioned dispersant, 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% by weight based on the organic silver salt. % Range is preferred.

In the present invention, the organic silver salt is 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 preferably added in the form of a water-soluble metal salt which is not a halide, specifically silver nitrate, silver sulfate, etc. It is preferable to add in the form.

  Addition with a halide is not preferable because it deteriorates image storability by the light (indoor light, sunlight, etc.) of the processed photosensitive material, so-called printability. For this reason, in this invention, adding in the form of the water-soluble metal salt which is not a halide is preferable.

The addition time of the metal ion selected from Ca, Mg, Zn and Ag preferably used in the present invention is after the formation of the particles of the non-photosensitive organic silver salt, immediately after the formation of the particles, before the dispersion, after the dispersion, and the coating solution. Any time may be used as long as it is just before coating, such as before and after preparation, and preferably after coating and before and after preparation of the coating solution. The addition amount of a metal ion selected from Ca, Mg, Zn and Ag in the present invention 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.

(Silver halide)
The photothermographic material of the present invention contains photosensitive silver halide. The photosensitive silver halide used in the present invention is not particularly limited as to the halogen composition, and silver chloride, silver chlorobromide, silver bromide, silver iodobromide and silver iodochlorobromide can be used.

  Regarding the grain formation of the photosensitive silver halide emulsion, grains can be formed by the method described in paragraph Nos. [0027] to [0224] of JP-A No. 11-11937. However, the method is particularly limited to this method. It is not something.

  Examples of the shape of the silver halide fine particles include cubes, octahedrons, tetradecahedrons, tabular shapes, spherical shapes, rod shapes, jade potato shapes, etc., but in the present invention, cubic grains or tabular grains are particularly preferred. Is preferred. The aspect ratio of the particles is the same as that described in paragraph [0225] of JP-A No. 11-11937 with respect to the characteristics of the particle shape such as the plane index.

  Further, the distribution of the halogen composition may be uniform in the inside and the surface of the silver halide grains, or may be continuously changed.

  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.

  As for the particle size distribution of silver halide grains, the value of monodispersity is 30% or less, preferably 1 to 20%, more preferably 5 to 15%. Here, the monodispersity is defined as a coefficient of variation, which is a percentage (%) of a value obtained by dividing the standard deviation of the particle size by the average particle size.

  For convenience, the grain size of silver halide grains is represented by the edge length in the case of cubic grains, and the other grains (octahedral, tetradecahedral, flat, etc.) are calculated by the equivalent circle diameter of the projected area.

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 in 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 preferable content is in the range of 1 × 10 ⁻⁹ to 1 × 10 ⁻³ mol per mol of silver, and more preferably in the range of 1 × 10 ⁻⁸ to 1 × 10 ⁻⁴ mol.

  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 paragraphs [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 in the present invention it may not be desalted.

  The photosensitive silver halide emulsion used in the present invention is preferably chemically sensitized. For chemical sensitization, it is preferable to use the method described in paragraphs [0242] to [0250] of JP-A-11-119374. A thiosulfonic acid compound may be added to the silver halide emulsion used in the present invention by the method shown in European Patent No. 293,917.

  As gelatin contained in the photosensitive silver halide used in the present invention, low molecular weight gelatin may be used in order to maintain a good dispersion state of the photosensitive silver halide emulsion in the organic silver salt-containing coating solution. preferable. The molecular weight of the low molecular weight gelatin is 500-60,000, preferably the molecular weight is 10,000-40,000.

  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 during grain formation, and low molecular weight gelatin may be used during dispersion after desalting. Although the density | concentration of a dispersion medium can be 0.05-20 mass%, on the handling, the density | concentration of 5-15 mass% is preferable.

  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.

  The silver halide emulsion of the photothermographic material of the present invention may be used alone or in combination of two or more (for example, those having different average grain sizes, those having different halogen compositions, those having different crystal walls, and chemical enhancement. You may use together the thing from which sensitivity conditions differ.

  As the usage-amount of silver halide, 0.01-0.5 mol of photosensitive silver halide is preferable with respect to 1 mol of organic silver salts, 0.02-0.3 mol is more preferable, 0.03-0. 25 mol is particularly preferred.

  Regarding the mixing method and mixing conditions of photosensitive silver halide and organic silver salt prepared separately, the silver halide and organic silver salt that were prepared respectively were mixed with a high-speed stirrer, ball mill, sand mill, colloid mill, prime mover mill, homogenizer. Etc., or a method of preparing an organic silver salt by mixing a photosensitive silver halide that has been prepared at any timing during the preparation of the organic silver salt, etc., but the effect of the present invention is sufficient As long as it is obtained, there is no particular limitation. In addition, mixing two or more types of photosensitive silver salt aqueous dispersions is a preferable method for adjusting photographic characteristics.

<High contrast accelerator>
The photothermographic material of the present invention can be used in combination with a high contrast accelerator for forming a high contrast image. Examples of the contrast accelerator include amine compounds described in U.S. Pat. No. 5,545,505, AM-1 to AM-5, and hydroxamic acids HA-1 to H-5 described in U.S. Pat. No. 5,545,507. HA-11, acrylonitriles described in US Pat. No. 5,545,507, CN-1 to CN-13, hydrazine compounds CA-1 to CA-6 described in US Pat. No. 5,558,983, No. 9-297368 Onium salts A-1 to A-42, B-1 to B-1 to B-27, C-1 to C-14, and the like can be used.

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

  In the photothermographic material of the invention, it is preferable to use an acid or a salt thereof obtained by hydrogenating diphosphorus pentoxide in combination with a high 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), hexametalin An acid (salt) etc. can be mentioned. Particularly preferable examples of the acid or salt thereof formed by adding hydrogenated 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.

  An acid or a salt thereof obtained by hydrogenating diphosphorus pentoxide, which can be preferably used in the present invention, is added to the image forming layer or a binder layer adjacent thereto from the viewpoint that a desired effect is exhibited in a small amount.

The amount of acid or its salt formed by diphosphorus pentoxide hydration (coating amount per 1 m ^{2 of} photothermographic material) may be a desired amount in accordance with the performance such as sensitivity and fogging. preferably ^{500mg / m 2, 0.5~100mg / m} 2 is more preferable.

《Reducing agent》
The photothermographic material of the present invention contains a reducing agent. The reducing agent preferably used in the present invention is an arbitrary substance that reduces silver ions to metallic silver, preferably an organic substance. 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 adding to layers other than an image forming layer, it is preferable to use 5-50 mol% more with respect to 1 mol of silver.

  The reducing agent may be a so-called precursor that is induced to function effectively only during development.

A wide range of reducing agents can be used in the photothermographic material of the invention. For example, JP-A Nos. 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, U.S. 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 It can be a reducing agent disclosed in such Patent 92,732. For example, amidooximes such as phenylamidooxime, 2-thienylamidooxime and p-phenoxyphenylamidooxime; azines such as 4-hydroxy-3,5-dimethoxybenzaldehyde azine; 2,2′-bis (hydroxymethyl) propionyl A combination of aliphatic carboxylic acid arylhydrazine and ascorbic acid, such as a combination of β-phenylhydrazine and ascorbic acid; a combination of polyhydroxybenzene and hydroxylamine, reductone and / or hydrazine (eg hydroquinone and bis (ethoxyethyl) A combination of hydroxylamine, piperidinohexose reductone or formyl-4-methylphenylhydrazine); phenylhydroxymic acid, p-hydroxyphenylhydride Hydroxamic acid such as ximic acid and β-aniline hydroxymic acid; a combination of azine and sulfonamidophenol (eg, phenothiazine and 2,6-dichloro-4-benzenesulfonamidophenol); ethyl-α-cyano-2- Α-cyanophenylacetic acid derivatives such as methylphenylacetate and ethyl-α-cyanophenylacetate; 2,2′-dihydroxy-1,1-binaphthyl, 6,6-dibromo-2,2-dihydroxy-1,1′- Bis-β-naphthol as exemplified by binaphthyl and bis (2-hydroxy-1-naphthyl) methane; bis-β-naphthol and 1,3-dihydroxybenzene derivatives (for example, 2,4-dihydroxybenzophenone, etc.) ) Combinations; 3-methyl-1-phenyl-5-pyrazolone, etc. 5-pyrazolones; reductones as exemplified by dimethylaminohexose reductone, anhydrodihydroaminohexose reductone and anhydrodihydropiperidone hexose reductone; 2,6-dichloro-4-benzenesulfonamidophenol And phonamide phenol reducing agents such as p-benzenesulfonamidophenol; 2-phenylindane-1,3-dione; coumarone such as 2,2-dimethyl-7-tert-butyl-6-hydroxycoumarone; 1,4-dihydropyridines such as 6-dimethoxy-3,5-dicarboethoxy-1,4-dihydropyridine; bisphenol (eg bis (2-hydroxy-3-tert-butyl-5-methylphenyl) methane, 2, 2-bis (4-hydroxy-3-methyl) Enyl) propane, 4,4-ethylidene-bis (2-tert-butyl-6-methylphenol), 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane and 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane); ascorbic acid derivatives (eg 1-ascorbyl palmitate, ascorbyl stearate); and aldehydes and ketones such as benzyl and acetyl; 3- Examples include pyrazolidone and certain indan-1,3-diones; chromanols (such as tocopherols). Particularly preferred reducing agents are bisphenol and chromanol.

  The reducing agent may be added by any method such as an aqueous solution, an organic solvent solution, a powder, a solid fine particle dispersion, and an emulsified dispersion. The solid fine particle dispersion may be added by a known refinement means (for example, a ball mill, a vibration ball mill, Sand mill, colloid mill, jet mill, roller mill, etc.). Further, a dispersing agent may be used when dispersing the solid fine particles.

《Coloring agent》
Inclusion of additives known as toning agents that improve images can increase the optical density. Also, toning agents can be advantageous in forming black silver images. The color toning agent is preferably contained in the layer on the image forming layer side with respect to the support in an amount of 0.1 to 50% mol, more preferably 0.5 to 20% mol per mol of silver. The toning agent may be a so-called precursor that is derivatized to function effectively only during development.

  A wide range of color toning agents can be used in the photothermographic material of the present invention. For example, JP-A Nos. 46-6077, 47-10282, 49-5019, 49-5020, 49-91215, 50-2524, 50-32927, 50-67132 50-67641, 50-114217, 51-3223, 51-27923, 52-14788, 53-1020, 53-76020, 54-156524, 54-156525, 61-183642, JP-A-4-56848, JP-B-49-10727, 54-20333, US Pat. Nos. 3,080,254, 3,446, No. 648, No. 3, 782, 941, No. 4,123,282, No. 4,510,236, British Patent No. 1,380,795, Belgian Patent No. 84 Can be used toning agent disclosed in like 910 A1.

  Specific examples of toning agents include phthalimide and N-hydroxyphthalimide; succinimide, pyrazolin-5-one, and quinazolinone, 3-phenyl-2-pyrazolin-5-one, 1-phenylurazole, quinazoline, and 2,4- Cyclic imides such as thiazolidinediones; naphthalimides (eg N-hydroxy-1,8-naphthalimide) cobalt complexes (eg cobalt hexamine trifluoroacetate); 3-mercapto-1,2,4-triazoles, 2, Mercaptans exemplified by 4-dimercaptopyrimidine, 3-mercapto-4,5-diphenyl-1,2,4-triazole and 2,5-dimercapto-1,3,4-thiadiazole; N- (aminomethyl) aryl Dicarboximide (eg N, N-dimethyl) Minomethyl) phthalimide and N, N- (dimethylaminomethyl) -naphthalene-2,3-dicarboximide); and blocked pyrazoles, isothiuronium derivatives and certain photobleaching agents (eg, N, N-hexamethylenebis ( 1-carbamoyl-3,5-dimethylpyrazole), 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-dimethoxyph Derivatives such as radinone and 2,3-dihydro-1,4-phthalazinedione; combinations of phthalazinone and phthalic acid derivatives (eg, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid, and tetrachlorophthalic anhydride) Phthalazine, phthalazine derivatives (eg, 4- (1-naphthyl) phthalazine, 6-chlorophthalazine, 5,7-dimethoxyphthalazine, 6-isobutylphthalazine, 6-tert-butylphthalazine, 5,7-dimethyl; Derivatives such as phthalazine and 2,3-dihydrophthalazine) or metal salts; phthalazine and its derivatives and phthalic acid derivatives (for example, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid, and tetrachlorophthalic anhydride); A combination of: quinazolinedione, benzoxazine or naphthooxy Sadine derivatives; rhodium complexes that function not only as color modifiers but also as a source of halide ions for in situ silver halide formation, such as hexachlororhodium (III) acid, ammonium, rhodium bromide, rhodium nitrate and hexachloro Rhodium (III) potassium and the like; inorganic peroxides and persulfates such as ammonium peroxide disulfide and hydrogen peroxide; 1,3-benzoxazine-2,4-dione, 8-methyl-1,3- Benzoxazine-2,4-diones such as benzoxazine-2,4-dione and 6-nitro-1,3-benzoxazine-2,4-dione; pyrimidines and asymmetric-triazines (eg, 2,4-dihydroxy Pyrimidine, 2-hydroxy-4-aminopyrimidine, etc.), azauracil, and tetraazapenta Derivatives such as 3,6-dimercapto-1,4-diphenyl-1H, 4H-2,3a, 5,6a-tetraazapentalene, and 1,4-di (o-chlorophenyl) -3,6- Dimercapto-1H, 4H-2, 3a, 5,6a-tetraazapentalene).

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

  The film surface pH on the image forming layer side of the photothermographic material of the present invention before heat development is 5.3 to 7.0, preferably 5.3 to 6.8. When the film surface pH is less than 5.3, sufficient contrast cannot be obtained, and when it exceeds 7.0, the fog increases when the development conditions become active (temperature increase or development time increase). Is not preferable.

In the present invention, the film surface pH means that 0.05 ml of water was added on the measurement surface of a 1 cm ² photosensitive material, and it was allowed to stand for 10 minutes in an atmosphere of 90% RH or more, and then it was confirmed that equilibrium was reached. And a value measured using a silver chloride flat composite electrode. Specific examples of the flat composite electrode include a pH meter manufactured by Toa Denpa Kogyo Co., Ltd.

  In order to adjust the film surface pH of the present invention to 5.3 to 7.0, acid or alkali is added for adjusting the film surface pH to obtain a predetermined film surface pH.

  The acid for adjusting the film surface pH used in the present invention may be either an organic acid or an inorganic acid, but acids such as citric acid, phthalic acid, citric acid ester, salicylic acid, phosphoric acid and orthophosphoric acid are preferred. . It may be added to any layer on the image forming layer side such as an undercoat layer or an image forming layer (emulsion layer) protective layer. The alkali for adjusting the film surface pH used in the present invention is preferably an alkali metal or alkaline earth metal hydroxide, and may be added to any layer on the image forming layer side.

<Anti-fogging agent / stabilizer>
In the photothermographic material of the present invention, the silver halide emulsion and / or the organic silver salt are further protected against the formation of additional fog by an antifoggant, a stabilizer and a stabilizer precursor, and are in stock storage. It is possible to stabilize against a decrease in sensitivity.

  These can be used alone or in combination. Suitable antifoggants, stabilizers and stabilizer precursors are the thiazonium salts described in U.S. Pat. Nos. 2,131,038 and 2,694,716, Azaindene described in U.S. Pat. Nos. 2,886,437 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, Sulfocatechol described in US Pat. No. 3,235,652, oxime, nitrone, nitroindazole described in British Patent 623,448, polyvalent metal salt described in US Pat. No. 2,839,405, US Pat. , 220,839, and palladium, platinum and gold salts described in U.S. Pat. Nos. 2,566,263 and 2,597,915. Halogen-substituted organic compounds described in U.S. Pat. Nos. 4,108,665 and 4,442,202, U.S. Pat. Nos. 4,128,557 and 4,137,079, 4,138, And triazine described in US Pat. No. 365,4,459,350, and phosphorus compounds described in US Pat. No. 4,411,985.

The photothermographic material of the present invention may contain benzoic acid for the purpose of increasing sensitivity and preventing fog. The benzoic acid preferably used in the present invention may be any benzoic acid derivative. Preferred examples include U.S. Pat. Nos. 4,784,939, 4,152,160, and JP-A-9-329863. Examples thereof include compounds described in 9-329864, 9-281737 and the like. 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 added to the organic silver salt-containing layer. Benzoic acid may be added at any step of preparing the coating solution. 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. To immediately before coating.

  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 tone.

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.

  The antifoggant preferably used in the present invention is an organic halide, for example, JP-A-50-119624, 50-120328, 51-121332, 54-58022, 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-11-87297 is preferably used as an antifoggant. Specifically, (P-1) to (P-118) described in the same specification are preferably used.

The addition amount of the organic halide is expressed as a mol 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 same specification are preferably used. The addition amount of salicylic acid represented by the formula (Z) is expressed as a mol amount (mol / mol Ag) relative to ¹ mol of Ag, preferably 1 × 10 ^{−5 to} 5 × 10 ⁻¹ mol / mol Ag, more preferably 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 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 cyclohexane, and mechanically emulsified dispersion. Can be created and 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 used in the present invention may be added to the layer on the image forming layer side with respect to the support, that is, the image forming layer or any other layer, but the image forming layer or adjacent thereto. It is preferable to add to the layer.

  In the case of a photothermographic material, the image forming layer is a layer containing a reducible silver salt (organic silver salt), and is preferably an image forming layer containing a photosensitive silver halide.

  The photothermographic material of the present invention 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 the storage stability before and after development.

  When a mercapto compound is used in the present invention, 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, Ar is an aromatic ring or condensed aromatic ring having one or more nitrogen, sulfur, oxygen, selenium or tellurium atoms, preferably a heteroaromatic ring such as benz Imidazole, naphthimidazole, benzothiazole, naphthothiazole, benzoxazole, naphthoxazole, benzoselenazole, benzotetrazole, imidazole, oxazole, pyrazole, triazole, thiadiazole, tetrazole, triazine, pyrimidine, pyradazine, pyrazine, pyridine, purine, quinoline or Quinazoline.

  These heteroaromatic rings are, for example, halogen (Br or Cl), hydroxy group, amino group, carboxy group, alkyl group (for example, those having 1 or more carbon atoms, preferably 1 to 4 carbon atoms), It has what is selected from the substituent group which consists of an alkoxy group (For example, 1 or more carbon atoms, Preferably it has 1-4 carbon atoms) and an aryl group (which may have a substituent). May be. Mercapto-substituted heteroaromatic compounds include 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, 2-mercaptobenzthiazole, 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) -quinazoline, 7-trifluoromethyl-4-quinolinethiol, 2,3,5,6-tetrachloro-4-pyridinethiol, 4-amino-6 Hydroxy-2-mercaptopyri Gin 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- Examples include (5-mercaptotetrazole) -sodium benzenesulfonate, N-methyl-N ′-(3- (5-mercaptotetrazolyl) phenyl) urea, 2-mercapto-4-phenyloxazole, and the like. Is not limited to these.

  The addition amount of these mercapto compounds is preferably in the range of 0.0001 to 1.0 mol per mol of silver in the image forming layer, more preferably 0.001 to 0.3 mol per mol of silver. is there.

  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. Preferably it is. The photothermographic material of the invention preferably has at least one back layer on the side opposite to the image forming layer (back surface) with respect to the support. These image forming layer, protective layer, and back layer As the binder, polymer latex is preferably used.

  By using polymer latex for these layers, water-based coating using a water-based solvent (dispersion medium) 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.

"binder"
As the binder used in the present invention, the polymer latex described below is preferably used.

  Of the image forming layers containing the photosensitive silver halide of the photothermographic material of the present invention, at least one layer 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 the photothermographic material of the present invention is used for printing applications in which dimensional change is a problem, the polymer latex may be used. It is preferable to use a polymer latex for the layer as well. However, the “polymer latex” referred to here is one in which a hydrophobic polymer insoluble in water is dispersed as fine particles in a water-soluble dispersion medium.

  Examples of the dispersion state include those in which a polymer is emulsified in a dispersion medium, those in which micelles are dispersed, and those in which polymer chains have a partially hydrophilic structure and molecular chains themselves are molecularly dispersed. But you can. The polymer latex used in the present invention is “synthetic resin emulsion (Hiraku Okuda, Hiroshi Inagaki, published by Kobunshi Kabushiki Kaisha (1978)”. Published in Molecular Publications (1993) "Synthetic Latex Chemistry (Muroichi Muroi, published by High Polymers Publishing (1970)".

  The average particle size of the dispersed particles is preferably in the range of 1 to 50000 nm, more preferably about 5 to 1000 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 preferably used in the present invention may be a so-called core / shell type latex other than an ordinary polymer latex having a uniform structure. In this case, it may be preferable to change the glass transition temperature between the core and the shell.

  The glass transition temperature (Tg) of the polymer latex preferably used for the binder of the photothermographic material of the present invention has different preferable ranges for 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 the photographic material during heat development. When used for a protective layer or a back layer, a glass transition temperature of 25 to 70 ° C. is preferable because it contacts various devices.

  The minimum film forming temperature (MFT) of the polymer latex preferably used in the photothermographic material of the present invention is about -30 to 90 ° C, more preferably about 0 to 70 ° C. A film-forming auxiliary may be added to control the minimum film-forming temperature. The film-forming aid is also called a plasticizer and is an organic compound (usually an organic solvent) that lowers the minimum film-forming temperature 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 preferably about 5,000 to 1,000,000, preferably about 10,000 to 100,000 in terms of average molecular weight. If the molecular weight is too small, the mechanical strength of the image forming layer is insufficient, and if it is too large, the film formability is poor, which is not preferable.

  Specific examples of the polymer latex preferably used as a binder in the image forming layer of the photothermographic material of the present invention include a latex of methyl methacrylate / ethyl acrylate / methacrylic acid copolymer, a latex of til methacrylate / butadiene / itaconic acid copolymer, and ethyl acrylate. Latex of methacrylic acid / methacrylic acid copolymer, latex of methyl methacrylate / 2-ethylhexyl acrylate / styrene / acrylic acid copolymer, latex of styrene / butajoene / acrylic acid copolymer, latex of styrene / butajoene / divinylbenzene / methacrylic acid copolymer, methyl methacrylate / Latex of vinyl chloride / acrylic acid copolymer, vinylidene chloride / ethylene acrylate / acrylonitrile / medium Such as latex of acrylic copolymer and the like. More specifically, copolymer latex of methyl methacrylate / ethyl acrylate / methacrylic acid = 33.5 / 50 / 16.5 (mass%), methyl methacrylate / butadiene / itaconic acid = 47.5 / 47.5 / 5 ( (Mass%) copolymer latex, ethyl acrylate / methacrylic acid = 95/5 (mass%) copolymer lax and the like. Such polymers are also commercially available. For example, as examples of acrylic resins, Sebian A-4635, 46583, 4601 (manufactured by Daicel Chemical Industries, Ltd.), Nipol LX811, 814, 821, 820, 857 (manufactured by Nippon Zeon Co., Ltd.), VONCORT-R3340, R3360, R3370, R4280 (manufactured by Dainippon Ink & Chemicals, Inc.). As polyester resins, FINETEX ES650, 611, 675, 850 (above, manufactured by Dainippon Ink Chemical Co., Ltd.), WD-size, WMS (above, manufactured by Eastman Chemical), etc., as polyurethane resins, HYDRAN AP10, 20 , 30, 40 (above, manufactured by Dainippon Ink Chemical Co., Ltd.) and the like, the rubber resins include LACSTAR 7310K, 3307B, 4700H, 7132C (above, manufactured by Dainippon Ink Chemical Co., Ltd.), Nipol LX410, 430, 435, 438 (above, manufactured by Nippon Zeon Co., Ltd.), etc., as vinyl chloride resins, G351, G576 (above, manufactured by Nippon Zeon Co., Ltd.), etc., and vinylidene chloride resins as L502, L513 (above, Asahi Kasei Kogyo) Aron D7020, D504, D5071 And Mitsui Toatsu Co., Ltd.), as the oleic resin, Chemipearl S120, SA100 (or, Mitsui Petrochemical Co., Ltd.) and the like.

  These polymers may be used alone or in combination of two or more as required.

  In the image forming layer, the polymer latex is preferably used as 50% by mass or more of the total binder, but the polymer latex is preferably used as 70% by mass or more. If necessary, a hydrophilic polymer such as gelatin, polyvinyl alcohol, methylcellulose, hydroxypropylcellulose, carboxymethylcellulose, hydroxypropylmethylcellulose or the like 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 prepared by applying an aqueous coating solution and then drying it. 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, isopropyl alcohol, methyl cellosolve, ethyl cellosolve, dimethylformamide, and ethyl acetate 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 / isopropyl alcohol = 90/10, water / dimethylformamide = 95/5, methanol / dimethylformamide = 80/15 / 5, water / methanol / dimethylformamide = 90/5/5 (however, the numbers represent mass%).

The total binder amount in the image forming layer is preferably 0.3 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.

  The image forming layer is preferably prepared by applying an aqueous coating solution and then drying it. 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, isopropyl alcohol, methyl cellosolve, ethyl cellosolve, dimethylformamide, and ethyl acetate 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 / isopropyl alcohol = 90/10, water / dimethylformamide = 95/5, methanol / dimethylformamide = 80/15 / 5, water / methanol / dimethylformamide = 90/5/5 (however, the numbers represent mass%).

The total binder amount in the image forming layer is preferably 0.3 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.

《Plasticizer / Crosslinking agent / Sliding agent》
In the present invention, the plasticizers described in paragraphs [0021] to [0025] of JP-A No. 2000-221634 are used as necessary (for example, benzyl alicol, 2,2,4-trimethylpentenediol-1,3). -Monoisobutyrate etc.) can be added to control the film-forming temperature.

  In each layer, a cross-link having a first polymer latex into which functional groups described in paragraphs [0023] to [0041] of JP-A No. 2000-1967 are introduced and a functional group capable of reacting with the first polymer latex. An agent and / or a second polymer latex can be used.

  The functional group is a carboxyl group, a hydroxyl group, an isocyanate group, an epoxy group, an N-methylol group, an oxazolinyl group, etc., and as a crosslinking agent, an epoxy compound, an assocyanate compound, a blocked isocyanate compound, a methylol compound, a hydroxy compound, a carboxy compound, It is selected from 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 (Sumitomo Bayer Urethane Co., Ltd.), Takenate WD725 (Takeda Pharmaceutical Co., Ltd.) as isocyanate compounds. Aquanate 100, 200 (manufactured by Nippon Polyurethane Co., Ltd.), water-dispersed polyisocyanate described in JP-A-9-160172; Sumitex M-3 (manufactured by Sumitomo Chemical Co., Ltd.) as an amino compound Deconal EX-614B (manufactured by Nagase Kasei Kogyo Co., Ltd.) as an epoxy compound; 2,4-dichloro-6-hydroxy-1,3,5-triazine sodium and the like as a halogen compound.

The total binder amount for the image forming layer is 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 0.2-10.0 g / m ² , more preferably 0.5-6.0 g / m ² . The total binder amount for the back layer is 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 that a polymer latex is used for at least one, particularly the outermost protective layer.

  A slipping agent can be used in the photothermographic material of the present invention. The “slip agent” as used in the present invention means a compound that, when present on the surface of an object, reduces the coefficient of friction of the object surface as compared to the case where it does not exist. The type is not particularly limited.

Examples of the slip agent preferably used in the present invention include compounds described in paragraphs [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), Hi-micron G-270 (main component stearic acid amide) (the above, Chukyo Yushi) (Made by)
W-1 C ₁₆ H ₃₃ —O—SO ₃ Na
W-2 C ₁₈ H ₃₇ —O—SO ₃ Na
Etc.

  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%.

<Undercoat layer>
JP-A 64-20544, JP-A-1-180537, JP-A-1-209443, JP-A-1-285939, 1-296243, JP-A-2-24649, JP-A-2-24648 are provided on both sides of the support. 2-184844, 3-109545, 3-137737, 3-141346, 3-141347, 4-96055, U.S. Pat. -68344, Japanese Patent No. 2,557,641, page 2, right column, line 20 to page 3, right column, line 30; Japanese Patent Application Laid-Open No. 2000-39684, paragraphs [0020] to [0037] It is preferable to provide an undercoat layer containing a vinylidene chloride copolymer containing 70% by mass or more of a vinylidene monomer 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 carboxyl group-containing vinyl monomer as a constituent repeating unit outside the vinylidene chloride monomer. When such a repeating unit is included, the vinyl chloride monomer alone causes the polymer (polymer) to crystallize, making it difficult to form a uniform film when coating the moisture-proof layer. This is because a carboxyl group-containing vinyl monomer is indispensable for stabilizing the (polymer). The molecular weight of the vinylidene chloride copolymer preferably used in the present invention is 45,000 or less in terms of mass average molecular weight, and more preferably 10,000 to 45,000. When the molecular weight increases, the adhesion between the vinylidene chloride copolymer layer and the polyester layer tends to deteriorate.

  The content of the vinylidene chloride copolymer preferably used in the present invention 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 vinylidene chloride copolymer. . The vinylidene chloride copolymer layer as the undercoat layer is preferably provided as the first undercoat layer directly provided on the support. Usually, one layer is provided on each side, but in some cases 2 More than one layer may be provided.

  When a multilayer structure having two or more layers is used, the total amount of the vinylidene chloride copolymer may be within the preferable range of the present invention. 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, the support may be coated with an undercoat layer using SBR, polyester, gelatin or the like as a binder, if necessary. These undercoat layers may have a multilayer structure, and may be provided on one side or both sides of the support. The thickness of the undercoat layer (per layer) is generally 0.01 to 5 μm, more preferably 0.05 to 1 μm.

<Support>
Various supports can be used in the photothermographic material of the invention. Preferred examples of the support include polyesters such as polyethylene terephthalate and polyethylene naphthalate, cellulose nitrate, cellulose ester, polyvinyl acetal, syndiotactic polystyrene, polycarbonate, and a paper support coated on both sides with polyethylene. Of these, biaxially stretched polyester, particularly polyethylene terephthalate (PET), is preferred 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. As the support preferably used in the photothermographic material of the present invention, biaxials described in JP-A Nos. 10-48772, 10-10676, 10-10777, 11-65025, and 11-138648 are disclosed. Polyester, particularly polyethylene terephthalate, which has been heat-treated in a humidity range of 130 to 185 ° C. in order to alleviate internal strain remaining in the film during stretching and eliminate heat shrinkage distortion generated during heat development processing, is particularly preferably used. The dimensional change rate of the support after such heat treatment at 120 ° C. for 30 seconds is −0.3 to + 0.01% in the machine direction (MD) and 0 to 0.04% in the transverse direction (TD). It is preferable.

<Antistatic agent>
In the photothermographic material of the invention, paragraphs [0040] to [0051] of JP-A No. 11-84573 are used for the purpose of reducing the adhesion of dust, preventing the generation of static marks, and preventing the conveyance failure in the automatic conveyance process. The conductive metal oxide and / or the fluorine-based surfactant described in 1) can be used for antistatic.

  Examples of the conductive metal oxide include acicular conductive metal tin oxide doped with antimony according to paragraphs [0012] to [0020] of US Pat. No. 5,575,957 and JP-A-11-223901. Fibrous tin oxide doped with antimony described in Kaihei 4-29134 is preferably used.

The surface 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 a relative humidity of 20%. Thereby, good antistatic properties can be obtained. The lower limit of the surface low efficiency 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 outermost surface of the opposite surface, preferably both, is 2000 seconds or less.

  The Beck smoothness can be easily determined according to Japanese Industrial Standard (JIS) P8119 “Smoothness test method using Beck tester for paper and paperboard” and TAPPI standard method T479.

  As described in paragraphs [0052] to [0059] of JP-A-11-94573, the outermost layer of the photothermographic material having the image forming layer and the Beck smoothness tooth of the outermost layer on the opposite side. It can be controlled by appropriately changing the particle size and addition amount of the matting agent contained in the layer.

《Thickener》
In the photothermographic material of 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 kind thereof is not particularly limited. Specifically, naturally occurring starches (corn starch, starch, etc.), seaweed (agar, sodium alginate, etc.), vegetable stickies (eg, gum arabic), animal proteins (such as glue, casein, gelatin, egg white), fermentation Adhesives (bululan, dextrin, etc.), semi-synthetic polymers such as starch (soluble starch, carboxyl starch, dextran, etc.), cellulose (viscose, methylcellulose, ethylcellulose, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, And hydroxypropylmethylcellulose). Furthermore, synthetic polymers (polyvinyl alcohol, polyacrylamide, polyvinyl pyrrolidone, polyethylene glycol, polypropylene glycol, polyvinyl ether, polyethylene mine, polystyrene sulfonic acid or copolymer thereof, polyvinyl sulfonic acid or copolymer thereof, polyacrylic acid or copolymer thereof) Polymers, acrylic acid or copolymers thereof, maleic acid copolymers, maleic acid monoester copolymers, acryloylmethylpropane sulfonic acid or copolymers 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 acroylmethylpropanesulfonic acid or a copolymer thereof, and the like, and particularly preferably used as a thickener.

  As these particularly preferred thickeners, gelatin, dextran, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, polyvinyl alcohol, polyacrylamide, polyvinylpyrrolidone, polystyrene sulfonic acid or a copolymer thereof, polyacrylic acid or a copolymer thereof, Maleic acid monoester copolymer. These compounds are described in detail in “Applications and Markets of New Water-Soluble Polymers” (CMC Co., Ltd., edited by Shinji Nagatomo, published on November 4, 1988).

  The amount of the water-soluble polymer used as a thickener is not particularly limited as long as the viscosity increases when added to the coating solution. Generally, the concentration in the liquid is 0.01 to 30% by mass, more preferably 0.05 to 20% by mass, and particularly preferably 0.1 to 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. The viscosity is a value measured at 25 ° C. with a B-type rotational viscometer.

  In addition to the 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 sales expansion at the time of addition.

<Surfactant>
The surfactant preferably used in the photothermographic material of the present invention is classified into a dispersant, a coating agent, a wetting agent, an antistatic agent, a photographic control agent and the like depending on the purpose of use. These objects can be achieved by appropriately selecting and using.

  As the surfactant preferably used in the present invention, either nonionic or ionic (anion, cation, betaine) can be used. Further, a fluorosurfactant is also preferably used.

  Preferred nonionic surfactants include surfactants having nonionic hydrophilic groups such as polyoxyethylene, polyoxypropylene, polyoxybutylene, polyglycidyl and sorbitan. Specifically, polyoxyethylene Alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene-polyoxypropylene glycol, polyhydric alcohol fatty acid partial ester, polyoxyethylene polyhydric alcohol fatty acid partial ester, polyoxyethylene polyhydric alcohol fatty acid ester, polyoxyethylene fatty acid ester And polyglycerol fatty acid ester, fatty acid diethanolamide, and triethanolamine fatty acid partial ester.

  Examples of anionic surfactants include carboxylates, sulfates, sulfonates, and phosphates. Typical examples include fatty acid salts, alkyl benzene sulfonates, alkyl naphthalene sulfonates, Alkyl sulfonate, α-olefin sulfonate, dialkyl sulfosuccinate, α-sulfonated fatty acid salt, N-methyl-N-oleyl taurine, petroleum sulfonate, alkyl sulfate, sulfated fat, polyoxyethylene alkyl Examples include ether sulfate, polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene styrenated phenyl ether sulfate, alkyl phosphate, polyoxyethylene alkyl ether phosphate, naphthalene sulfonate formaldehyde condensate, etc. .

  Examples of cationic surfactants include amine salts, quaternary ammonium salts, pyridium salts, and the like. First to third fatty acid amine salts, quaternary ammonium salts (tetraalkylammonium salts, trialkylbenzylammonium salts). , Alkyl pyridium salts, alkyl imidazole salts, etc.).

  Examples of betaine surfactants include carboxybetaine and sulfobetaine, and examples include N-trialkyl-N-carboxymethylammonium betaine and N-trialkyl-N-sulfoalkyleneammonium betaine.

  These surfactants are described in “Application of Surfactant” (Sachibo, Takao Karie, published on September 1, 1980).

The preferred surfactant in the photothermographic material of the present invention is not particularly limited in the amount used, and may be any amount that provides the desired surfactant properties. The coating amount of the fluorosurfactant is preferably 0.01 to 250 mg per 1 m ² .

Although the specific example of surfactant is described below, these are not limited. (Here, -C ₆ H ₄ represents a phenylene group).

WA-1: C ₁₆ H ₃₃ (OCH ₂ CH ₂ ) ₁₀ OH
_{WA-2: C 9 H 19} -C 6 H 4 - (OCH 2 CH 2) 12 OH
WA-3: Sodium dodecylbenzenesulfonate WA-4: Sodium tri (isopropyl) naphthalenesulfonate WA-5: Sodium tri (isobutyl) naphthalenesulfonate WA-6: Sodium dodecyl sulfate WA-7: α-sulfosuccinic acid di (2-ethylhexyl) ester sodium salt _{WA-8: C 8 H 17} -C 6 H 4 - (OCH 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 COO (-)
WA-11: C ₈ H ₁₇ SO ₂ N (C ₃ H ₇ ) (CH ₂ CH ₂ O) ₁₆ H
_{WA-12: C 8 H 17} SO 2 N (C 3 H 7) CH 2 COOK
WA-13: C ₈ H ₁₇ SO ₃ K
_{WA-14: C 8 H 17} SO 2 N (C 3 H 7) (CH 2 CH 2 O) 4 (CH 2) 4 SO 3 Na
_{WA-15: C 8 H 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 H 17} SO 2 N (C 3 H 7) CH 2 CH 2 CH 2 N (+) (CH 3) 2 -CH 2 COO (-)
<Image forming layer, protective layer, intermediate layer, antihalation layer>
In 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 beat coating, curtain coating, and the like, but the slide peat coating method shown in FIG. 1 of JP-A-2000-2964 is particularly preferable. In the case of a silver halide photosensitive material using gelatin as a main binder, it is rapidly cooled in the first drying zone provided downstream of the coating die. As a result, gelatin gelation occurs, and the coating film is cooled and solidified. . The coating film which 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 roller-supported support, or a support is wound around a cylindrical duct in a spiral shape and transported and dried. Examples include the pickling method (air floating method).

  When layer formation is performed using a coating solution whose binder main component is a polymer latex, the flow of the coating solution cannot be stopped by rapid cooling, and thus preliminary drying may be insufficient only in the first drying zone. In this case, in a drying method such as that used in silver halide photographic light-sensitive materials, flow unevenness and dry unevenness occur, and a serious defect tends to occur on the coated surface.

  A preferable drying method in the present invention is a method of drying in the horizontal drying zone until constant rate drying is completed, regardless of the first drying zone or the second drying zone described in JP-A-2000-2964. .

  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 may be between 0 and 70 ° C. The horizontal drying zone 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 means a drying process in which all of the inflowing heat with a constant liquid film temperature is used for evaporation of the solvent. Decreased drying means that at the end of drying, the drying rate decreases due to various factors (such as the receding of the evaporation surface where the internal diffusion of moisture transfer is rate limiting), and the applied heat is also used to increase the liquid film temperature. Means the 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 photographic light-sensitive 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 the protective layer are such that the liquid film surface temperature during constant rate drying is 3 to 5 from the minimum film forming temperature of the polymer latex (MTF; usually the glass transition temperature (Tg) of the polymer). It is preferable that the temperature be higher than (° C.). Usually, it is often 25 to 40 ° C. due to the limitation of production equipment. Further, the dry bulb temperature at the rate of drying is preferably a temperature lower than the Tg of the support (usually 80 ° C. or less in the case of polyethylene terephthalate).

  In the present invention, the liquid film surface temperature means the solvent liquid film surface temperature of the solvent liquid film of the coating liquid film applied to 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 polymer latex quickly forms a film, while the lower layer such as the image forming layer does not stop fluidity. Therefore, unevenness is likely to occur on the surface. Further, when excessive heat higher than Tg is applied to the support (base), 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, the coating liquid properties for performing simultaneous multilayer coating in which the upper layer is applied before drying the lower layer and both layers are simultaneously dried. The pH difference between the image forming layer coating solution and the protective layer coating solution is preferably 2.5 or less, and the pH difference is preferably as small as possible. When the pH difference of the coating solution increases, microaggregation tends to occur at the coating solution interface, and a serious surface failure such as coating streaks tends to occur during continuous 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, more preferably 20 to 50 mPa · s at 25 ° C.

  These viscosities are measured with a B-type viscometer. The winding after drying is preferably performed under the conditions of a temperature of 20 to 30 ° C. and a relative humidity of 45 ± 20%. The winding shape may have the surface on the image forming layer side outside in accordance with the subsequent processing mode. Moreover, when a processing form is a roll product, in order to remove the curl which generate | occur | produced with the winding form, it is also preferable to make it the roll form wound on the opposite side to the winding form at the time of a process. The relative humidity of the photosensitive material is preferably controlled in the range of 20 to 55% (25 ° C.).

A conventional photographic emulsion coating solution, which is a viscous liquid containing silver halide and containing gelatin, usually has a bubble dissolved and disappears just by feeding under pressure, and even if it is returned to atmospheric pressure during coating. There is almost no bubble deposition. However, in the case of an image forming layer coating liquid containing an organic silver salt dispersion and a polymer latex that is preferably used in the present invention, degassing tends to be insufficient only by pressure feeding, so that a gas-liquid interface is likely to occur. It is preferable to apply ultrasonic vibration and rub the defoamed liquid while feeding. The defoaming of the coating solution is degassed under reduced pressure before the coating solution is applied, and the solution is continuously fed so as to maintain a pressurized state of 1.5 kg / cm ² or more and to easily generate a gas-liquid interface. However, a method of applying ultrasonic vibration 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, 1.5 kg / cm ² or more is preferable, and 1.8 kg / cm ² is more preferable. Although there is no restriction | limiting in particular in the upper limit, Usually, it is about 5 kg / cm < ² >. 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. However, if the sound pressure is too high, the sound pressure is partially increased. Becomes hot 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 a tank (usually a liquid preparation tank or a storage tank) is hermetically depressurized to increase the bubble diameter in the coating liquid and to defoam by increasing the buoyancy. vacuum conditions 7.733 × 10 ^-2 MPa or lower pressure conditions than, preferably a 7.065 × 10 ^-2 MPa or lower pressure conditions than its lowest pressure condition is not particularly limited, usually 1 It is about 066 × 10 ⁻² MPa. The decompression time is 30 minutes or more, preferably 45 minutes or more, and the upper limit is not particularly limited.

In the present invention, the image forming layer, the image forming layer protective layer, the undercoat layer, and the back layer contain a dye for the purpose of preventing halation described in paragraphs [0204] to [0208] of JP-A No. 11-84573. Can do. Various dyes and pigments can be used in the image forming layer from the viewpoint of improving the color tone and preventing irradiation. Any dyes and pigments may be used for the image forming layer. For example, compounds described in paragraph [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 it is generally preferable to use 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 in a desired range, and after treatment, absorption in the visible region is sufficiently small, and any shape of the preferred absorbance spectrum of the back layer can be obtained. It may be a compound.

  For example, the compounds described in paragraph [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, as described in JP-A No. 54-17833, by decoloring by light irradiation. A method for reducing the concentration can be used.

<< Light source for exposure to PS plate >>
When the photothermographic material of the present invention is used as a mask when a plate is produced with a PS plate after heat development, the photothermographic material after heat development sets exposure conditions for the PS plate in a plate making machine. Information for setting plate making conditions such as mask document and PS plate conveyance conditions, etc. are carried as image information. Accordingly, the concentration (amount of use) of the irradiation dye, the halation dye, and the 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 range of the sensor is low, and the absorbance is 0.3 or less.

  For example, the plate making machine S-FNRIII manufactured by Fuji Photo Film Co., Ltd. uses a light source with a wavelength of 670 nm as a detector for detecting a registration mark and a barcode reader. A light source having a wavelength of 670 nm is used as a barcode reader. That is, when Dmin near 670 nm is high, information on the film cannot be detected accurately, 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 around 670 nm needs to be low, and the absorbance at 660 to 680 nm after heat development needs to be 0.3 or less, preferably 0.25 or less. is there. The lower limit is not limited, but is usually about 0.10.

In the present invention, 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), a light emitting diode (LED) is used. ) Is preferably used. In particular, LD is more preferable in terms of high output and high resolution.

Any of these light sources may be used as long as they can generate light having an electromagnetic spectrum in a target wavelength range. For example, in the case of LD, a dye laser, a gas laser, a solid laser, a semiconductor laser, or the like can be used. 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) or AlGaAsSb (1250 to 1400) can be given. In the present invention, the color light-sensitive 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 selected from the light fluxes of semiconductor lasers of 670, 680, 750, 780, 810, 830, and 880 nm.

In the present invention, a second harmonic generation element (SHG element) is also preferably used. However, the second harmonic generation element applies a nonlinear optical effect to convert the wavelength of the laser light into a half. For example, LiM ²⁺ M ³⁺ F ₆ (M ²⁺ = Ca, Sr, Cd, M ³⁺ = Al, Ga, Ti) and KH ₂ PO ₄ (KDP) were used as nonlinear optical crystals. In addition, an optical waveguide device in which Li ⁺ is ion-exchanged with H ⁺ in a LiNbO ₃ crystal can be used (NIKKEIELECTNICS 1986. 7.14 ( no, 399, p. 89-90), etc., the output device described in JP-A-63-226552 can be used in the present invention.

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. The overlap can be expressed quantitatively by FWHM / scanning pitch width (overlap coefficient), for example, when the beam diameter is expressed by the half width (FWHM) of the beam intensity. In the exposure of the photothermographic material of the present invention, this 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 . Further, it is preferably several μJ / cm ² to several tens μJ / cm ² . The scanning method of the light source of the exposure apparatus preferably 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, or the like can be used. The light source channel 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 irradiating a photosensitive material with a laser beam described in JP-A-5-113548, a multimode disclosed in International Publication WO95 / 31754, etc. Methods using lasers are known and these techniques are preferably used.

<Heat development>
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 of the photothermographic material exposed imagewise is heated and developed. As a preferable and preferred embodiment of the heat development automatic developing machine used, as a type in which the heat development photosensitive 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 and 9- No. 297385 and International Publication WO95 / 30934, a heat developing automatic developing machine, as a non-contact type, Japanese Patent Application Laid-Open Nos. 7-13294, WO97 / 28489, 97/28488, 97/28487 There is an automatic heat developing machine described. A particularly preferred embodiment is a non-contact type heat development automatic developing machine. The preferred heat 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, heating is performed for 5 seconds or more so that an image does not appear at a temperature of 80 ° C. or higher and lower than 115 ° C. It is effective to adopt a method (so-called multi-step heating method) in which an image is formed by heat development with the above method.

  When the photothermographic material of the present invention is subjected to heat development processing, it is exposed to a high temperature of 110 ° C. or higher, so that a part of the components contained in the photosensitive material or a part of the decomposition component by heat development is present. Volatilizes. These volatile components cause uneven development, corrode the components of the automatic thermal development machine, precipitate at low temperatures and cause deformation of the screen as a foreign object, or adhere to the screen as dirt. It is known that there are various adverse effects. As a method for removing these influences, it is known that a filter is installed in the automatic thermal development machine and the air flow in the thermal development automatic development machine is optimally adjusted. These methods can be used effectively in combination.

  International Publication Nos. WO95 / 30933, 97/21150, JP-T-10-500496, etc. have a bonded absorbent particle, a first opening for introducing volatiles, and a second opening for discharging. It is described that a filter cartridge having the above is used for a heating device that heats a photothermographic material in contact. 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.

  These can be preferably used in the heat development processing of the photothermographic material of the present invention. In US Pat. No. 4,518,845 and JP-B-3-54331, a device for removing vapor from the photothermographic material, a heating device for pressing the photothermographic material against the heat transfer member, and the heat transfer member are heated. A configuration having a device to perform 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 can also be preferably used in the present invention.

<< Heat Development Automatic Developing Machine Having Preheat Section of the Present Invention >>
FIG. 1 shows a side view of a heat development automatic developing machine having a preheating portion in front of a heat development portion used for heat development processing of the heat development photosensitive material of the present invention.

  In FIG. 1, the photothermographic material 10 is conveyed from the carry-in roller pair 11 to the carry-out roller 12 while being preheated and corrected to a flat shape. The carry-in roller pair 11 is composed of a silicon rubber roller at the top and an aluminum heat roller at the bottom. During this time, the photothermographic material 10 is preheated and then thermally developed.

  The transport of the heat development unit is a smooth surface in which a plurality of rollers 13 are provided on the surface contacting side on the image forming layer side, and a nonwoven fabric, Teflon (registered trademark) or the like is bonded to the side on which the back surface on the opposite side contacts 14 is provided. The photothermographic material 10 is conveyed while the back surface is slid on the smooth surface 14 by driving of a plurality of rollers 13 that are in contact with the surface on the image forming layer side, and is set on the upper portion of the roller 13 and the lower portion of the smooth surface 14. Heat development is performed by the heater 15. As the heating means in this case, a plate heater or the like can be mentioned. The clearance between the roller 13 and the smooth surface 14 is appropriately adjusted to a clearance that the photothermographic material 10 can convey, but is preferably 0 to 1 mm.

  The material of the surface of the roller 13 and the member of the smooth surface 14 are resistant to high temperatures and may be anything as long as it does 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 Teflon ( (Registered trademark) non-woven fabric is preferred.

  As the heating means, it is preferable that a plurality of heaters are used and the heating temperature can be set freely. The heating unit is composed of a preheating part A having a pair of carry-in rollers 11 and a heat development processing part B provided with a heater 15. However, the preheating part A provided in front of the heat development processing part B is heat development. It is preferably lower than the temperature, for example, about 10 to 30 ° C., preferably set to a temperature and time sufficient to evaporate the amount of water in the photothermographic material 10, and higher than the Tg of the support of the photothermographic material. Preferably, the temperature distribution of the preheated portion and the heat development processing portion B is preferably ± 1 ° C. or less, and more preferably ± 0.5 ° C. or less.

  Further, a guide plate 16 is provided after the heat development processing part B, and a slow cooling part C having the carry-out roller 12 and the guide plate 16 is provided. The guide plate 16 is preferably made of a material having low thermal conductivity. In order to prevent deformation of the photothermographic material 10, the cooling is preferably performed gradually, and the cooling rate is preferably 0.5 to 10 ° C./second.

<Film surface pH of image forming layer>
The film surface pH on the image forming layer side of the photothermographic material of the present invention is 5.3 to 7.0, and particularly preferably 5.6 to 6.8. “Film surface pH” in the present invention means that 0.05 ml of water was added on the measurement surface of a 1 cm ² photosensitive material and allowed to stand for 10 minutes in an atmosphere of 90% RH or more, and it was confirmed that equilibrium was reached. The value measured using a silver chloride flat composite electrode. Specific examples of the flat electrode include a pH meter manufactured by Toa Denpa Kogyo Co., Ltd.

  In the present invention, it is preferable to add an acid or an alkali in order to set the film surface pH to a predetermined value.

  The acid for adjusting the film surface pH preferably used in the present invention may be either an organic acid or an inorganic acid, but is preferably an acid such as citric acid, phthalic acid, citrate ester, salicylic acid, phosphoric acid, or orthophosphoric acid. It may be added to any layer on any side of the image forming layer such as a layer or an image forming layer (emulsion layer) protective layer.

  As an apparatus for thermally developing the photothermographic material of the present invention, an apparatus having a preheating portion in front of the heat developing portion is used. There may be a plurality of preheating sections. For example, four sets of preheating sections that can be independently temperature controlled are used, and can be controlled to 85 ° C., 90 ° C., 95 ° C., and 100 ° C., respectively. Such a method is described in JP-A-54-30032, which can remove moisture and organic solvent contained in the photothermographic material out of the system, Changes in the shape of the support of the photothermographic material due to heating can be suppressed.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.

Example 1
<< Preparation of silver halide emulsion A >>
After dissolving 11 g of alkali-processed gelatin (calcium content of 2700 ppm or less), potassium bromide 30 mg and sodium 4-methylbenzenesulfonate 1.3 g 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, potassium bromide 1 mol / liter (NH ₄ ) ₂ RhCl ₅ (H ₂ O) 5 × 10 ⁻⁶ mol / liter and K ₃ IrCl ₆ 2 × 10 ⁻⁵ mol An aqueous solution containing 1 liter / liter was added over 6 minutes 30 seconds by the controlled double jet method while maintaining pAg 7.7.

Subsequently, 476 ml of an aqueous solution containing 55.5 g of silver nitrate and a halogen salt aqueous solution containing 1 mol / liter of potassium bromide and 2 × 10 ⁻⁵ mol / liter of K ₃ IrCl ₆ were maintained by pAg 7.7 by a controlled double jet method. It was added over 28 minutes and 30 seconds. Thereafter, the pH was lowered to cause coagulation sedimentation, followed by desalting, and 51.1 g of low molecular weight gelatin having an average molecular weight of 15,000 (calcium content of 20 ppm or less) was added to adjust the pH to 5.9 and pAg 8.0. The obtained 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, 71 μmol of triethylthiourea was added after 3 minutes, and then ripened for 100 minutes. Hydroxy-6-methyl-1,3,3a, 7 tetrazaindene (5 × 10 ⁻⁴ mol) and 0.17 g of compound A were added, and 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 (ethanol) with respect to 1 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 prepare a silver halide emulsion A.

<< Preparation of silver behenate dispersion A >>
Behenic acid (produced by Henkel, Edenor C22-85R) 87.6 g, distilled water 423 liters, 5 mol / liter NaOH aqueous solution 49.2 liters, tert-butyl alcohol 120 liters WO mixed, and stirred at 75 ° C. for 1 hour. Reaction was performed to obtain a sodium behenate solution.

  Separately, 206.2 liters of an aqueous solution containing 40.4 kg of silver nitrate was prepared and kept at 10 ° C. A reaction vessel containing 635 liters of distilled water and 30 liters of tert-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 silver nitrate aqueous solution were kept constant at 62 minutes and 10 seconds, respectively. And added over 60 minutes. At that time, after the addition of the aqueous silver nitrate solution, only the aqueous silver nitrate solution is added for 7 minutes and 20 seconds, and then the addition of the sodium behenate solution is started. After the addition of the aqueous silver nitrate solution, only the sodium behenate solution is added for 9 minutes and 30 seconds. Was added. At this time, the temperature in the reactor was set to 30 ° C. and controlled so that the liquid temperature did not rise. The pipe of the addition system for the sodium behenate solution was kept warm by steam tracing, and the amount of steam was controlled so that the liquid temperature at the outlet of the addition nozzle tip was 75 ° C. Moreover, the piping of the addition system of the silver nitrate aqueous solution was kept warm by circulating cooling water outside the double pipe. The addition position of the sodium behenate aqueous 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 thus filtered 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 (manufactured by Kuraray Co., Ltd., PVA-217, average polymerization: about 1700) and water are added to the wet cake equivalent to 100 g of the dry solid content, and the total amount is set to 385 g, and then preliminarily prepared with a homomixer. Distributed. Next, the pre-dispersed stock solution is processed three times by adjusting the pressure of the disperser (Microfluidics International Corporation, Microfluidizer M-110S-EH, using GIOZ 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 MasterSizerX (manufactured by Malvern Instruments Ltd). When evaluated by electron microscope photography, 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 (ratio of equivalent circle diameter to particle thickness of the projected area of the particle) was 5.1. .

<< Preparation of solid fine particle dispersion of reducing agent >>
To 10 kg of a 20% by weight aqueous solution of 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane and 10 kg of a modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) Nord 104E (Nissin Chemical Co., Ltd. 400 g, methanol 640 g, and water 16 kg were added and mixed well to obtain a slurry. The slurry was fed with a diaphragm pump and filled with zirconia beads having an average diameter of 0.5 mm. After dispersing for 3 hours and 30 minutes in a horizontal sand mill (IMM Co., Ltd., UVM-2), 4 g of sodium benzoisothiazolino and water are added to adjust the concentration of the reducing agent to 25% by mass. In this way, the reducing agent particles contained in the obtained dispersion had a median diameter of 0.44 μm and a maximum particle diameter. .0μm below. The resulting dispersion was a variation coefficient of 19% of the average particle diameter was filtered with a polypropylene filter having a pore size of 3.0 [mu] m, and then stored to remove artifacts such as dust.

<< Preparation of Solid Fine Particle Dispersion of Organic Polyhalogen Compound-A >>
Organic polyhalogen compound-A: 10 kg of tribromomethyl (4- (2,4,6-trimethylphenylsulfonyl) phenyl) sulfone and 10 kg of a 20% by weight aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) 639 g of a 20% by mass aqueous solution of sodium triisopropylnaphthalenesulfonate, 400 g of Surfynol 104E (Nisshin Chemical Co., Ltd.), 640 g of methanol and 16 kg of water were added and mixed well to obtain a slurry. The solution was fed with a diafuran pump and dispersed for 5 hours in a horizontal sand mill (UVM-2 manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm. Then, water was added to the organic polyhalogen compound-A. Adjust to a concentration of 25% by mass, organic polyhalogen compound A solid dispersion of -A was obtained, and the organic polyhalogen compound particles contained in the dispersion thus obtained had a median diameter of 0.36 μm, a maximum particle diameter of 2.0 μm or less, and a coefficient of variation of 18% in the average particle diameter. The obtained dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign matters such as dust and stored.

<< Preparation of Solid Dispersion of Organic Polyhalogen Compound-B >>
Organic polyhalogen compound-B: 5 kg of tribromomethylnaphthylsulfone, 2.5 kg of 20% by weight aqueous solution of modified polyvinylchol (Kuraray Co., Ltd., Poval MP203), 213 g of 20% by weight aqueous solution of sodium triisopropylnaphthalenesulfonate, 10 kg of water was added and mixed well to make a slurry. This slurry was fed with a diafuran pump and dispersed for 5 hours in a horizontal sand mill (UVM-2 manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm. Then, 2,5 g of sodium benzoisothiazolinone And water were added to adjust the concentration of the organic polyhalogen compound-B to 23.5% by mass to obtain a solid fine particle dispersion of the organic polyhalogen compound-B. The organic polyhalogen compound particles contained in the dispersion thus obtained had a median diameter of 0.38 μm, a maximum particle diameter of 2.0 μm or less, and an average particle diameter variation coefficient of 20%. The obtained dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign matters such as dust and stored.

<< Preparation of Organic Polyhalogen Compound-C >>
Preparation recipe (Ratio per 100 ml of finished quantity and preparation procedure.
(1) Water 75.0ml
(2) 8.6 ml of 20% aqueous solution of sodium tripropylnaphthalenesulfonate
(3) 5% aqueous solution of sodium dihydrogen orthophosphate dihydrate 6.8 ml
(4) 1 mol / liter aqueous solution of potassium hydroxide 9.5 ml
(5) Organic polyhalogen compound-C 4.0 g
(3-Tribromomethanesulfonylbenzoylaminoacetic acid)
The preparation procedure was as follows.
1. While stirring at room temperature, (1) to (4) were sequentially added, and after (4) was added, the mixture was stirred and mixed for 5 minutes.
2. Further, the powder of (5) 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 Emulsion Dispersion of Compound Z >>
10 kg of R-054 (manufactured by Sanko Co., Ltd.) containing 85% by mass of compound Z and 11.66 kg of MIBK (methyl isobutyl ketone) were mixed and then purged with nitrogen and dissolved at 80 ° C. for 1 hour. To this solution, 25.52 kg of water, 12.76 g of a 20 mass% aqueous solution of MP polymer (manufactured by Kuraray Co., Ltd., MP-203) and 0.44 kg of a 20 mass% aqueous solution of sodium triisopropylnaphthalenesulfonate were added. The mixture was emulsified and dispersed at ˜40 ° C. and 3600 rpm for 6 minutes. Furthermore, 0.08 kg of Surfinol 104E (manufactured by Nissin Chemical Co., Ltd.) and 47.94 kg of water were added to this solution and distilled under reduced pressure to remove MIBK, so that the concentration of compound Z was 10% by mass. Adjusted. The particles of Compound Z contained in the dispersion thus obtained had a median diameter of 0.19 μm, a maximum diameter of 1.5 μm or less, and a coefficient of variation of the particle diameter of 17%. The obtained dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign matters such as dust and stored.

<< Preparation of 6-isopropylphthalazine compound dispersion >>
Preparation formulation (rate per 100 g of finished dispersion) and preparation procedure.
(1) 62.35 g of water
(2) Modified polyvinyl alcohol 2.0g
(Kuraray Co., Ltd., Poval MP203)
(3) 25.5 g of polyvinyl alcohol
(Kuraray Co., Ltd., PVA-217, 10 mass% aqueous solution)
(4) Sodium tripropylnaphthalenesulfonate (20% by mass aqueous solution)
3.0g
(5) 6-isopropylphthalazine (70% by mass aqueous solution) 7.15 g
The dispersion was prepared in the following steps.
1. While stirring (1) at room temperature, (2) was added so as not to become 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 matters such as dust and stored.

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

<< Preparation of solid fine particle dispersion of development accelerator A >>
10 kg of the development accelerator A, 10 kg of a 20% by weight aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) and 20 kg of water were added and mixed well to obtain a slurry. The slurry was fed with a diaphragm pump and dispersed for 5 hours in a horizontal sand mill (UVM-2 manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm. The concentration was adjusted to 20% by mass to obtain a solid fine particle dispersion of development accelerator A. The development accelerator particles contained in the dispersion thus obtained had a median diameter of 0.5 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 matters such as dust and stored.

<Preparation of image forming layer coating solution>
The following binder, raw material and silver halide emulsion A were added to 1 mol of silver of the silver behenate dispersion A prepared above, and water was added to prepare an image forming layer coating solution. After completion, vacuum degassing 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 Industries, SBR latex, Tg17 ° C)
397g as solid
1-bis (2-hydroxy-3,5-dimethylphenyl)
-3,5,5-trimethylhexane 149.5 g as solid content
Organic polyhalogen compound B 36.3 g as solid content
Organic polyhalogen compound C as solids 2.34 g
Sodium ethylthiosulfonate 0.47g
Benzotriazole 1.02g
Polyvinyl alcohol (Kuraray Co., Ltd., PVA-235) 10.8 g
6-isopropylphthalazine 15.0 g
Compound Z 9.7g as solid content
Hardeners 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)
Application amount that optical density of 783 nm becomes 0.3 As a guideline, solid content 0.40 g
Silver halide emulsion A Ag amount 0.06 mol Compound A as preservative, 40 ppm in coating solution 2.5 mg / m ² as coating amount
1% by mass as the total amount of solvent in the methanol coating solution
2% by mass as the total amount of solvent in the ethanol coating solution
The glass transition point of the coating film was 17 ° C.

  Further, the film surface pH of the image forming layer was measured by the above-described methods and shown in Table 1.

<< Preparation of coating solution for protective 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 (mass%) (Tg46 as copolymer) ° C (calculated value), solid content concentration of 21.5% by mass, compound A at 100 ppm, further compounding aid 15% by mass of compound D as a film-forming aid, and Tg of coating solution at 24 ° C The water was added to 943 g of an average particle diameter of 116 nm), 1.62 g of compound E, 114.8 g of an aqueous solution of organic polyhalogen compound-C, 17.0 g of organic halogen compound-A as a solid content, dihydrogen orthophosphate 0.69 g of sodium dihydrate as solid content, 11.55 g of development accelerator A as solid content, matting agent (polystyrene Particles, average particle size 7 μm, average particle size variation coefficient 8%) 1.58 g and polyvinyl alcohol (manufactured by Kuraray Co., Ltd., PVA-235) 29.3 g are added, water is further added, and the coating liquid (methanol solvent is added). 0.8% by mass) was prepared.

  After completion, vacuum degassing was performed at a pressure of 0.47 atm 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 liquid >>
Polymer latex solution of methyl methacrylate / styrene / 2-ethylhexyl acrylate / 2-hydroxyethyl methacrylate / acrylic acid = 58.9 / 8.6 / 25.4 / 5.1 / 2 (mass%) (Tg46 as copolymer) ° C (calculated value), 21.5% by mass as a solid content concentration, 100 ppm of compound A, and further 15% by mass of compound D as a film-forming aid with respect to the latex solid content. Water was added to 625 g at an average particle diameter of 74 nm at a temperature of 0.3 ° C., Compound C was 0.32 g, Compound E was 0.13 g, Compound F was 11.7 g, Compound H was 2.7 g, and polyvinyl alcohol (Kuraray Co., Ltd.) Manufactured, PVA-235) 11.5 g was added, and water was further added to prepare a coating solution (containing 0.1% by mass of methanol solvent).

  After completion, vacuum degassing was performed at a pressure of 0.47 atm 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 (mass%) (Tg46 as copolymer) ° C (calculated value), 21.5% by mass as a solid content concentration, 100 ppm of compound A, and further 15% by mass of compound D as a film-forming aid with respect to the latex solid content. Water was added to 649 g at an average particle diameter of 116 nm, which was set to 0 ° C., and 18.4 g of a 30% by mass solution of Carnava wax (manufactured by Chukyo Yushi Co., Ltd., Cellosol 524, silicon content of less than 5 ppm), 0.23 g of Compound C 1.85 g of compound E, 1.0 g of compound G, matting agent (polystyrene particles, average particle diameter 7 μm, variation coefficient of average particle diameter 8%) 3.45 g, and polyvinyl alcohol (Kuraray Co., Ltd., added PVA-235) 26.5 g, was prepared further coating solution by adding water to (a methanol solvent 1.1% by weight containing).

  After completion, vacuum degassing was performed at a pressure of 0.47 atm for 60 minutes. The coating solution had a pH of 5.3 and a viscosity of 25 mPa · s at 25 ° C.

<< Preparation of polyethylene terephthalate (PET) support with back / undercoat layer >>
(1) Preparation of PET support Using terephthalic acid and ethylene glycol, according to a conventional method, polyethylene terephthalate having an intrinsic viscosity of 1 V = 0.66 (measured at 25 ° C. in phenol / tetrachloroethane = 6/4 (mass ratio)) Obtained. 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 of 120 µm after heat setting 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.

(2) Preparation of undercoat layer and back layer 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 following composition was applied at 6.2 ml / It was coated on a support so as to be m ² and dried at 125 ° C. for 30 seconds, 150 ° C. for 30 seconds, and 185 ° C. for 30 seconds.

Latex-A 280g
KOH 0.5g
Polystyrene fine particles (average particle size: 2 μm, average particle size variation coefficient 7%) 0.03 g
1.8 g of 2,4-dichloro-6-hydroxy-s-tothiazine
Compound Bc-C 0.097g
Distilled water Amount to give a total amount of 1000 g Undercoat second layer A coating solution having the composition shown below was applied onto the undercoat first layer so as to be 5.5 ml / m ² , at 125 ° C. for 30 seconds, 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% by weight aqueous solution) 10 g
Compound-Bc-A 0.04 g
25 g of methylcellulose (2% by weight aqueous solution)
Polyethyleneoxy compound 0.3g
Distilled water Total amount of 1000 g Back first layer Corona discharge treatment of 0.375 kV · A · min / m ² is performed on the surface opposite to the surface coated with the undercoat layer, and the surface has the composition shown below. The coating solution 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% by mass aqueous dispersion, manufactured by Nippon Pure Chemical Co., Ltd.) 23g
Alkali-treated gelatin (molecular weight 10,000, Ca ²⁺ content 30 ppm) 4.44 g
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
Water-soluble melamine compound (Sumitomo Chemical Co., Ltd., Sumtex Resin M-3, 8% by mass aqueous solution) 15 g
FD-10D 24g
(Aqueous dispersion of Sb-doped SnO ₂ needle particles, manufactured by Ishihara Sangyo Co., Ltd.)
Polystyrene fine particles (average particle size 2 μm, average particle size variation coefficient 7%) 0.03 g
Distilled water Amount to give a total amount of 1000 g 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 30 seconds at 125 ° C. and 30 seconds at 150 ° C. Second, at 170 ° C. for 30 seconds.

Jurimar ET410 57.5g
(30% by mass aqueous dispersion, manufactured by Nippon Pure Chemicals Co., Ltd.)
Polyoxyethylene phenyl ether 1.7g
Water-soluble melamine compound 15g
(Sumitomo Chemical Industries, Ltd., Sumitex Resin M-3, 8 mass% aqueous solution)
Cerosol 524 (30% by mass aqueous solution, manufactured by Chukyo Yushi Co., Ltd.) 6.6 g
Distilled water Total amount of 1000 g Back third layer Apply the same coating solution as the undercoat first layer on the back second layer to 6.2 ml / m ² , at 125 ° C. for 30 seconds, at 150 ° C. It was dried for 30 seconds at 170 ° C. for 30 seconds.

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

Latex-B 286g
Compound-Bc-B 2.7 g
Compound-Bc-C 0.6 g
Compound-Bc-D 0.5g
2.5 g of 2,4-dichloro-6-hydroxy-s-triazine
7.7 g of polymethyl methacrylate
(10% by mass aqueous dispersion, average particle size 5 μm, average particle size variation coefficient 7%)
Distilled water Amount that makes the total amount 1000g

(Latex-A)
Core-shell type latex with 90% by mass of core part and 10% by mass of shell part Core part Vinylidene chloride / methyl acrylate / methyl methacrylate / acrylonitrile / acrylic acid = 93/3/3 / 0.9 / 0.1 (mass%)
Shell part Vinylidene chloride / methyl acrylate / methyl methacrylate / acrylonitrile / acrylic acid = 88/3/3/3/3 (mass%) mass average molecular weight 38000
(Latex-B)
Methyl acrylate / styrene / 2-ethylhexyl acrylate / 2-hydroxyethyl methacrylate / acrylic acid = 59/9/26/5/1 (mass% copolymer)
(3) Transport heat treatment (3-1) 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 the tension was 2 kg / cm ² . It was conveyed at a speed of 20 m / min.

(3-2) Post-heat treatment Subsequent to the heat treatment, it was passed through a zone of 40 ° C. for 15 seconds, followed by post-heat treatment and winding. The winding tension at this time was 10 kg / cm ² .

<< Preparation of photothermographic material >>
Using the slide beat coating method disclosed in FIG. 1 of Japanese Patent Application Laid-Open No. 2000-2964 on the undercoat layer of the PET support on the side where the undercoat first layer and the undercoat second layer are applied, the above image is used. The forming layer coating solution was applied so that the applied silver amount was 1.5 kg / m ² . Further thereon, the protective layer coating solution was applied simultaneously with the image forming layer coating solution so that the polymer latex solid content coating amount was 1.29 g / m ² . Thereafter, on the protective layer, the lower layer overcoat layer coating solution has a polymer latex solids coating amount of 1.97 g / m ² and the upper layer overcoat layer coating solution has a polymer latex solids coating amount of 1.07 g. A photothermographic material was prepared by simultaneous multilayer coating with a lower overcoat coating solution so as to be / m ² .

  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 a temperature of 23 ± 5 ° C. and a relative humidity of 45 ± 5%. The winding shape is adjusted to the subsequent processing mode (image-forming layer side outer winding), and the image-forming layer side is outside. did. The packaged humidity of the photothermographic material was 20 to 40% relative humidity (measured at 25 ° C.), and the Beck smoothness was 560.

<Evaluation of practical concentration>
The obtained photothermographic material was subjected to 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 60000 rpm and an exposure time of 1.2 × 10 ⁻⁸ seconds. The overlap coefficient at this time was 0.449, and the laser energy density on the surface of the 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 / inch, the following thermal development processing is performed, and Dmax (maximum) when exposed at an LV value at which the halftone dot is 50% The (concentration) part was measured and used as the practical concentration.

<Heat development processing>
The exposed photothermographic material was subjected to heat development using a heat development automatic developing machine FDS-6100X (Fuji Film Co., Ltd.). 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 performed in the development processing section at 120 ° C. (photothermographic material surface temperature) in 17.2 seconds and the slow cooling section in 13.6 seconds. The temperature accuracy in the width direction was ± 0.5 ° C. The temperature of each roller was set 5 cm longer on both sides than the width of the photothermographic material (for example, 61 cm in width), and the temperature was applied to that portion so that a temperature system was obtained. In addition, since both ends of each roller are drastically lowered in temperature, the portion that is 5 cm longer than the width of the heat-development sensitive material is set so that the temperature is 1 to 3 ° C. higher than the central portion of the roller. Care was taken to ensure that the image density of the material (e.g. within a 61 cm width) was a homogeneous finish.
The sample photothermographic material was allowed to stand for 16 hours in an environment of 25 ° C., 80% RH and 10% RH, and Dmin and Dmax were measured for each photothermographic material.

<< Evaluation of ratchet against fluctuations in development conditions >>
In order to evaluate the latitude with respect to fluctuations in development conditions, a sample of the photothermographic material was allowed to stand in an environment of 25 ° C. and 10% RH for 16 hours. This time, only the heat development temperature was 115 ° C. for 20 seconds. Further, development was performed under the conditions of 115 ° C. and 25 seconds, and the width of the latitude was evaluated. Gamma (γ) is represented by the slope of a straight line connecting the points of density 0.2 and 2.0 with the logarithm of the exposure dose as the horizontal axis.

  The obtained results are summarized in Table 1.

  As is clear from Table 1, the photothermographic materials 1 to 7 to 1-14 containing the high contrast agent represented by the general formula (1) of the present invention have stable Dmin and Dmin even in a low temperature environment and a high temperature environment. It can be seen that the latitude obtained when the development conditions change is also widely excellent.

Example 2
Sample No. 1 prepared in Example 1 was used. Evaluation similar to Example 1 except that 1-1 to 1-14 were subjected to heat development using a heat development automatic developing machine having a preheat part in front of the heat development part, with the set temperature of the preheat part being 100 ° C. (Sample Nos. 2-1 to 2-14). As a result, good results were obtained in the same manner as in Example 1.

  From Table 2, it can be seen that the Dmax of the sample of the present invention using the heat developing automatic developing machine having the preheating portion is better.

1 is a conceptual side view showing a configuration of a heat development automatic developing machine used in an image forming method using a heat development photosensitive 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)

An image forming layer containing a non-photosensitive organic silver salt, a reducing agent of the non-photosensitive organic silver salt, a photosensitive silver halide, a high contrast agent and a binder on a support, and a non-photosensitive layer for protecting the image forming layer In each of the photothermographic materials having at least one layer, the contrast-enhancing agent is a compound represented by the following general formula (1), and the pH of the film surface of the image forming layer is 5.3 to 7.0. A photothermographic material characterized by the above.

[Wherein, X represents an alkoxy group, an aryloxy group, an amino group, or an alkylamino group, Y represents an alkyl group, an aryl group, or a heterocyclic group, and M represents a cation other than a hydrogen ion. ] The photothermographic material according to claim 1, wherein the photothermographic material is processed using a heat development automatic developing machine having a preheating part in front of the heat developing part and having a temperature of 80 to 120 ° C. Image forming method.

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