JP2006201347A - Method for producing nonphotosensitive organic silver salt and photothermographic material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a nonphotosensitive organic silver salt, when being used for a photothermographic material, having satisfactory photographic performance (fog and preservability) and free from unevenness in coating. <P>SOLUTION: In the method for producing a nonphotosensitive organic silver salt, at the time when a nonphotosensitive organic silver salt is produced, as a stage 1, water, an organic solvent, or a mixture of water and an organic solvent, and a part of a silver ion-containing aqueous solution to be added are added to the inside of a reaction vessel, and also, the solution in the reaction vessel is stirred, so as to control the pAg of the solution to 2.5 to 3.8, and next, as a stage 2, the temperature in the reaction vessel is controlled to 20 to 40°C, also, a silver ion-containing aqueous solution and an aqueous solution of an aliphatic acid alkali metal salt are simultaneously added, so as to be stirred, and its pH is controlled to 4 to 8, thus the nonphotosensitive organic silver salt is produced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a non-photosensitive organic silver salt and a photothermographic material, and more specifically, a non-photosensitive organic silver in which an alkali metal salt solution of an aliphatic carboxylic acid and a silver ion solution are simultaneously added to a reaction vessel. The present invention relates to a method for producing a salt and a photothermographic material containing the non-photosensitive organic silver salt.

  Conventionally, in the fields of printing plate making and medical treatment, waste liquids resulting from wet processing of image forming materials have been a problem in terms of workability. In recent years, reduction of processing waste liquids has been strongly desired from the viewpoint of environmental conservation and space saving. It is rare. Therefore, there has been a need for a technique relating to a photothermographic material for photographic technology that can be efficiently exposed by a laser image setter or a laser imager and can form a clear black image with high resolution.

  As a technique for this purpose, a photothermographic material (hereinafter also referred to as a photosensitive material) for forming a photographic image using a thermal development processing method is well known (for example, see Non-Patent Document 1).

  By the way, the organic silver salt used as a non-photosensitive silver source in the photothermographic material is basically an aliphatic carboxylic acid added with a caustic alkali or alkali metal salt in water to form an alkali soap, and then the alkali soap is converted into a silver soap ( It is prepared by adding silver nitrate to replace (organic silver salt) (for example, see Patent Document 1). In addition, alcohol may be added to enhance the concentration effect and uniformity (see, for example, Patent Document 2).

  Since the alkaline soap is alkaline, the silver soap is made at a high pH. However, the addition of silver nitrate to the alkaline solution generates silver oxide as a by-product, and also causes unintended silver nuclei. Such a by-product is disadvantageous in terms of the performance of the photothermographic material, in particular, fogging.

On the other hand, in order to produce a photothermographic material using an organic silver salt, it is necessary to disperse the organic silver salt in a binder to form a coating film. In this case, it is known that many problems relating to film forming properties and coating properties occur as compared with ordinary silver halide. This is considered to be because the silver salt of a fatty acid having a large volume per mole occupies a large proportion of the binder. At present, there is known a method for dealing with the problem by increasing the binder ratio, but as a result, it has many adverse effects such as affecting the photographic performance. The film forming property is disclosed in terms of the addition amount of a silver ion solution and an alkali metal salt solution of an aliphatic carboxylic acid (see, for example, Patent Document 3), but the applicability is not solved. With regard to applicability, the problem of uneven density is large and fatal in medical diagnosis, and an early solution is desired.
D. Morgan: Dry Silver Photographic Materials; Handbook of Imaging Materials, Marcel Dekker, Inc. Page 48, (1991) JP 2000-143578 A (pages 1 and 2) JP 2000-7683 A (pages 1 and 2) JP 2001-163890 A (pages 1 and 2)

  The present invention has been made in view of the above problems, and its object is to provide a non-photosensitive organic silver salt having good photographic performance (fogging, storage stability) and no coating unevenness when used in a photothermographic material. It is to provide a manufacturing method.

  The above object of the present invention can be achieved by the following configuration.

(Claim 1)
When producing the non-photosensitive organic silver salt, as part 1, in the reaction vessel, 1 part of water, an organic solvent, or a mixture of water and an organic solvent, and an aqueous solution containing silver ions to be added are added. And the liquid in reaction container is stirred and pAg of liquid is set to 2.5-3.8. Next, as process 2, the temperature in this reaction container is controlled to 20-40 degreeC, and silver ion is made Production of a non-photosensitive organic silver salt characterized in that an aqueous solution containing and an aqueous solution of a fatty acid alkali metal salt are simultaneously added and stirred, and the pH is controlled to 4 to 8 to produce a non-photosensitive organic silver salt Method.

(Claim 2)
2. The method for producing a non-photosensitive organic silver salt according to claim 1, wherein the pAg in Step 1 in producing the non-photosensitive organic silver salt is 2.8 to 3.1.

(Claim 3)
The method for producing a non-photosensitive organic silver salt according to claim 1 or 2, wherein the temperature in the reaction vessel in Step 2 when producing the non-photosensitive organic silver salt is 20 to 30 ° C.

(Claim 4)
The non-photosensitive organic silver according to any one of claims 1 to 3, wherein the pH in the reaction vessel in step 2 in producing the non-photosensitive organic silver salt is controlled to 4-6. Method for producing salt.

(Claim 5)
The method for producing a non-photosensitive organic silver salt according to any one of claims 1 to 4, wherein a stirring Reynolds number of the reaction solution in the reaction vessel is 125,000 or more and 350,000 or less.

(Claim 6)
The number of circulations per unit time by stirring of the reaction solution in the reaction vessel is 4.3 times / minute or more and 12.0 times / minute or less, 5. Of producing a non-photosensitive organic silver salt.

(Claim 7)
A photosensitive layer containing a non-photosensitive organic silver salt produced by the production method according to any one of claims 1 to 6, a photosensitive silver halide grain, a reducing agent and a binder on a support. A photothermographic material characterized by the above.

  The photothermographic material prepared by using the non-photosensitive organic silver salt produced by the method of the present invention has good photographic performance (fogging and storage properties), and can provide an excellent photothermographic material having no coating unevenness. .

  The present invention will be described in more detail. In the method for producing a non-photosensitive organic silver salt of the present invention, an alkali metal salt solution of an aliphatic carboxylic acid (hereinafter also referred to as an organic acid) and an aqueous solution containing silver ions (also referred to as a silver ion-containing solution) are contained in a reaction vessel. It is prepared by adding and reacting simultaneously. The reaction is usually allowed to proceed by adding the respective solution into the reaction vessel. It is preferable to put a solution in the reaction vessel in advance, and such a solution may be water, an organic solvent, or a mixture of water and an organic solvent.

  Examples of non-photosensitive organic silver salts suitable for the present invention are described in Research Disclosure Nos. 17029 and 29963, including: That is, a silver salt of an aliphatic carboxylic acid (for example, a silver salt of gallic acid, oxalic acid, behenic acid, arachidic acid, stearic acid, palmitic acid, lauric acid, etc.); a silver carboxyalkylthiourate (for example, 1- ( Silver salt of 3-carboxypropyl) thiouric acid, 1- (3-carboxypropyl) -3,3-dimethylthiouric acid, etc .; silver complex of polymer reaction product of aldehyde and hydroxy-substituted aromatic carboxylic acid (for example, aldehyde Complex of polymer reaction products with alcohols (formaldehyde, acetaldehyde, butyraldehyde, etc.), hydroxy-substituted aromatic carboxylic acids (eg salicylic acid, benzoic acid, 3,5-dihydroxybenzoic acid, 5,5-thiodisalicylic acid) ); Silver salts or complexes of thiones (eg, 3- (2-carboxyethyl) -4-hydroxy Silver salt or complex of methyl-4-thiazoline-2-thione); imidazole, pyrazole, urazole, 1,2,4-thiazole and 1H-tetrazole, 3-amino-5-benzylthio-1,2,4-triazole and A complex or salt of nitrogen acid and silver selected from benzotriazole; silver salt such as saccharin and 5-chlorosalicylaldoxime; silver arachidate and silver stearate. In the present invention, silver behenate, silver arachidate, and silver stearate are particularly preferable.

  As the alkali metal salt of the aliphatic carboxylic acid preferably used in the present invention, it is preferable to add the alkali metal salt first before the addition of the aliphatic carboxylic acid. This is to increase the solubility of the aliphatic carboxylic acid by using an aqueous solution of an alkali metal salt as the ground solution. The addition method may be either batch addition or divided addition.

  As the alkali metal salt preferably used in the present invention, potassium hydroxide is most suitable. The solubility can be further increased by using potassium hydroxide. Although the solubility can be increased by using alcohol, it is not suitable for production cost.

  Furthermore, in the present invention, the primary addition amount (the initial addition amount in divided additions or the total amount in batch addition) is preferably 60 mol% or more with respect to the number of moles of the aliphatic carboxylic acid. More preferably, it is 80 mol% or more, More preferably, it is 90 mol% or more. By these preparation methods, the aliphatic carboxylic acid can be dissolved more quickly, and a uniform alkali soap can be prepared in a short time.

  Although the silver ion containing solution used for this invention will not be restrict | limited especially if it is a solution containing silver ion, Especially the aqueous solution of silver nitrate is preferable. Acid and alkali can be added to adjust the pH of the aqueous silver nitrate solution. The type of acid and alkali is not particularly limited. In step 1, the silver ion-containing solution is added to water, an organic solvent, or a mixture of water and an organic solvent in the reaction vessel, so that the pAg of the liquid in the reaction vessel is 2.5 to 3.8. The addition amount is preferably 0.1 to 2.0% by mass.

  In the method for producing a non-photosensitive organic silver salt of the present invention, the total amount of pAg of the aqueous solution containing the silver ions is 2.5 to 3.8, preferably 2.8 to 3.1. An aqueous solution of a fatty acid alkali metal salt is added before the start of addition. This is because if pAg is too low, residual silver ions in the early stage of silvering increase and unexpected fog nuclei are generated. In addition, if the fatty acid alkali metal salt is added in advance, the initial pH at the same time of addition increases, and silver oxide is likely to be generated, causing fogging.

  The production method of the present invention is characterized in that the pH in the reaction vessel is adjusted to 4 to 8, preferably 4 to 6. This is because the silveration reaction rate is controlled by adjusting the pH of the organic silver salt during silver formation. This is because if the pH is too low, the precipitation of fatty acids is large, whereas if the pH is too high, silver oxide is likely to be generated. The pH can be adjusted by adjusting the flow rate of acid, alkali correction solution, or fatty acid alkali metal salt.

  Furthermore, in the manufacturing method of this invention, the temperature in reaction container is 40 degrees C or less, Preferably it is 30 degrees C or less, More preferably, it is 20 degrees C or less. Adjusting the temperature has the effect of making the silvering rate constant. If the temperature is too high, the silvering reaction will increase, but the residual ions will accelerate the reaction of unexpected fog nuclei. Therefore, the lower the temperature, the more advantageous for suppressing fog nuclei, but the aqueous solution of the fatty acid alkali metal salt is high (80 ° C. or higher), so that 40 ° C. or lower is appropriate in terms of equipment, and the desired performance can be expected. is there.

  There is no limitation on the apparatus used for the production method of the present invention. In particular, for the stirring device, for example, a bulk stirring type such as an anchor blade or a paddle blade, an emulsifying dispersion type such as a dissolver or a homogenizer, or any combination thereof can be used. Moreover, the addition time of the alkali metal salt solution of aliphatic carboxylic acid and the silver ion solution can be arbitrarily selected. For example, it can be added by a method of adding at a constant addition rate, an accelerated addition method or a slow addition method using an arbitrary time function.

  In the stirring of the production method of the present invention, the stirring Reynolds number in the reaction vessel is 125,000 or more and 350,000 or less. A preferred Reynolds number is from 150,000 to 300,000. Below 125000, the silver chloride reaction does not occur quickly, and there is a concern that unintended silver nuclei are generated and the fog of the photothermographic material is increased. On the other hand, if it exceeds 350,000, it is not suitable for production due to concerns that the load on the motor, which is a stirring member, will be excessive, risk on equipment, and the like.

  The Reynolds number here can be calculated by the following equation.

Re = D ² · n · ρ / μ
Here, Re: Stirring Reynolds number [−]
D: Diameter of stirring blade [m]
n: Stirring rotation speed [s-1] (rotation speed per second [rps])
ρ: Density of liquid [kg / m ³ ]
μ: Liquid viscosity [kg / m · s]
It is.

  Furthermore, the production method of the present invention is characterized in that the number of circulations per unit time of the reaction solution in the reaction vessel is 4.3 times / min or more and 12.0 times / min or less. The number of circulations is preferably 5.0 times / min to 10.0 times / min. If it is less than 4.3 times / minute, the reaction solution tends to be non-uniform, and there is a concern that unintended silver nuclei are generated and fogging of the photothermographic material is increased. On the other hand, if it exceeds 12.0 times / minute, the load on the motor, which is a stirring member, may become excessive, and it will not be suitable for production due to equipment risks. The number of circulations means the number of circulations per minute by the discharge of the stirrer. In the present invention, the reaction can be carried out quickly by setting the stirring conditions to satisfy the Reynolds number or the circulation number.

  The average particle size of the non-photosensitive organic silver salt of the present invention is preferably from 0.5 μm to 3 μm, more preferably from 0.5 μm to 1 μm. If it is less than 0.5 μm, there is a concern that the particle size is small and the development reaction is accelerated, making it difficult to use as a photothermographic material. On the other hand, if it exceeds 3 μm, the development reaction becomes slow, which may be disadvantageous for rapid processing of the photothermographic material. The average particle diameter here means the diameter of a circle having an area corresponding to the projected area of the non-photosensitive organic silver salt, that is, the “circle equivalent diameter”.

  In the present invention, the crystals of the non-photosensitive organic silver salt may or may not be desalted after formation. However, when desalting is performed, a method known in the art such as a flotation separation method or a centrifugal separation method is used. It can be desalted by washing with water.

  The crystals of the non-photosensitive organic silver salt of the present invention can be subjected to a drying step for removing moisture before the dispersing step. There is no particular limitation on the drying apparatus applied in the present invention, and any apparatus can be used. Examples of the drying apparatus used in the present invention include a vacuum dryer, a freeze dryer, a hot air heating type box dryer, an airflow dryer, a spray dryer, a fluidized bed dryer, etc. An airflow dryer is preferably used in the present invention. In the present invention, the drying may be performed twice or more from the viewpoints of productivity and prevention of overdrying.

  The dispersion of the non-photosensitive organic silver salt of the present invention is pre-dispersed with a non-photosensitive organic silver salt and a dispersing binder together with a surfactant if necessary, and then dispersed and pulverized with a media disperser or a high-pressure homogenizer (main dispersion) It is preferable to do. For the preliminary dispersion, a general stirrer such as an anchor type or propeller type, a high speed rotating centrifugal radiation type stirrer (dissolver), or a high speed rotating shear type stirrer (homomixer) can be used.

  In the present invention, the photosensitive silver halide may be mixed in any step such as during preparation of the organic silver salt or during dispersion of the organic silver salt or immediately before coating. However, it is necessary to perform sufficient mixing using an appropriate stirring member.

(Polymer soluble in both water and organic solvents)
In the present invention, it is preferable to use a polymer that is soluble in both water and an organic solvent as a binder. The polymer that is soluble in both water and the organic solvent may be any of natural resins, polymers and copolymers, and synthetic resins, polymers and copolymers. For example, it is possible to use gelatins, rubbers and the like that have been modified to belong to the category of the present invention. Alternatively, polymers belonging to the following classifications can be used by introducing functional groups so as to be suitable for the present invention. Poly (vinyl alcohol) s, hydroxyethyl celluloses, cellulose acetates, cellulose acetate butyrates, poly (vinyl pyrrolidone) s, casein, starch, poly (acrylic acid and acrylate esters), poly (methyl methacrylic acid and methacrylic acid) Acid esters), poly (vinyl chloride) s, poly (methacrylic acid) s, styrene-maleic anhydride copolymers, styrene-acrylonitrile copolymers, styrene-butadiene copolymers, poly (vinyl acetal) (Eg, poly (vinyl formal) and poly (vinyl butyral)), poly (esters), poly (urethanes), phenoxy resins, poly (vinylidene chloride) s, poly (epoxides), poly (carbonates) , Poly (vinyl acetate) s, poly ( Olefins), cellulose esters, and polyamides. Several types of these polymers may be copolymers, but polymers obtained by copolymerizing monomers of acrylic acid, methacrylic acid and esters thereof are particularly preferable.

  In the present invention, the polymer that dissolves in both water and organic solvent may be a polymer that dissolves in both water and organic solvent in the same state, but may be dissolved in water or organic solvent by controlling pH or controlling temperature. Included are those that can be insolubilized. For example, in the nonionic active agent, the phenomenon of cloud point is well known, but it becomes lipophilic and soluble in organic solvents when the temperature rises, and it has a property that it becomes hydrophilic, that is, soluble in water when the temperature is lowered. The polymer having is also included in the present invention. It is sufficient that micelles are formed and uniformly emulsified even if they are not completely dissolved. Alternatively, a polymer having an acidic group such as a carboxylic acid becomes hydrophilic in a dissociated state depending on the type, but can be made oleophilic and soluble in a solvent by lowering the pH to a non-dissociated state. Conversely, a polymer having an amino group becomes lipophilic when the pH is raised, and when it is lowered, the polymer is ionized to increase the water solubility. In the present invention, since various monomers are combined, it is not generally stated which monomer should be used and how much, but a desired polymer can be obtained by combining a hydrophilic monomer and a hydrophobic monomer in an appropriate ratio. Can be easily understood.

  The polymer that dissolves in both the water and the organic solvent may have a solubility of at least 1% by mass (25 ° C.) with respect to water, although it may be adjusted by adjusting the dissolution conditions such as pH as described above or may not be adjusted. In addition, an organic solvent having a solubility of 5% by mass or more (25 ° C.) in methyl ethyl ketone is preferable.

  As a polymer which dissolves in both water and an organic solvent according to the present invention, a so-called block polymer or comb type (graft) polymer is more suitable than a linear polymer from the viewpoint of solubility. A comb type polymer is particularly preferable. When manufacturing a comb type polymer, various methods can be used, but it is desirable to use a monomer capable of introducing a side chain having a molecular weight of 200 or more into a comb part (side chain). In particular, it is preferable to use a polyoxyalkylene group-containing ethylenically unsaturated monomer such as ethylene oxide or propylene oxide.

  As the polyoxyalkylene group-containing ethylenically unsaturated monomer, those having a polyoxyalkylene group represented by the following general formula are particularly preferable.

-(EO) _l- (PO) _m- (TO) _n -R
Here, E represents an ethylene group, P represents a propylene group, T represents a butylene group, and R represents a substituent. Examples of the butylene group include a tetramethylene group and an isobutylene group. l represents an integer of 1 to 300, m represents an integer of 0 to 60, and n represents an integer of 0 to 40. Preferably, l is 1 to 200, m is 0 to 30, and n is 0 to 20. However, l + m + n ≧ 2.

  The substituent represented by R represents an alkyl group, an aryl group, a heterocyclic group, etc., and the alkyl group is methyl, ethyl, propyl, butyl, hexyl, octyl. Examples of dodecyl groups include aryl groups such as phenyl and naphthyl, and examples of heterocyclic groups include thienyl and pyridyl groups. In addition, these groups are further halogen atoms, alkoxy groups (methoxy group, ethoxy group, butoxy group, etc.), alkylthio groups (methylthio group, butylthio group, etc.), acyl groups (acetyl group, benzoyl group, etc.), alkaneamide groups ( An acetamide group, a propionamide group, etc.), an arylamide group (benzoylamide group, etc.) and the like may be further substituted. Further, these substituents may be further substituted with these groups.

  The polyoxyalkylene group represented by the general formula can be introduced into the polymer by using an ethylenically unsaturated monomer having these polyoxyalkylene groups. Examples of ethylenically unsaturated monomers having these groups include (polyoxyalkylene) acrylates and methacrylates, and (polyoxyalkylene) acrylates and methacrylates are commercially available hydroxy poly (oxyalkylene) materials such as commercial products. The names “Pluronic” (Pluronic (Asahi Denka Kogyo Co., Ltd.)), Adeka Polyether (Asahi Denka Kogyo Co., Ltd.), Carbowax [Carbowax (Glico Products)], Triton [Toriton (Rohm and Haas) (From Rohm and Haas))] and P.I. E. What is marketed as G (made by Daiichi Kogyo Seiyaku Co., Ltd.) can be manufactured by making it react with acrylic acid, methacrylic acid, acrylic chloride, methacrylic chloride, acrylic anhydride, etc. by a well-known method. Separately, poly (oxyalkylene) diacrylate produced by a known method can also be used.

  Moreover, as a monomer of a commercial item, it is Blemmer PE-90, Blemmer PE-200, Blemmer PE-350, Blemmer AE-90, Blemmer AE-200 as a hydroxyl-terminated polyalkylene glycol mono (meth) acrylate manufactured by NOF Corporation. , Blemmer AE-400, Blemmer PP-1000, Blemmer PP-500, Blemmer PP-800, Blemmer AP-150, Blemmer AP-400, Blemmer AP-550, Blemmer AP-800, Blemmer 50PEP-300, Blemmer 70PEP-350B Blemmer AEP series, Blemmer 55PET-400, Blemmer 30PET-800, Blemmer 55PET-800, Blemmer AET series, Blemmer 30PPT-800, Blenmer Over 50PPT-800, Blemmer 70PPT-800, Blemmer APT series, Brenmer 10PPB-500B, and the like Brenmer 10APB-500B. Similarly, Blemmer PME-100, Blemmer PME-200, Blemmer PME-400, Blemmer PME-1000, Blemmer PME-4000, Blemmer AME-400, Blemmer as alkyl-terminated polyalkylene glycol mono (meth) acrylates manufactured by NOF Corporation. 50POEP-800B, Blemmer 50AOEP-800B, Blemmer PLE-200, Blemmer ALE-200, Blemmer ALE-800, Blemmer PSE-400, Blemmer PSE-1300, Blemmer ASE series, Blemmer PKEP series, Blemmer AKEP series, Blemmer AE-300 , Blemmer ANE-1300, Blemmer PNEP series, Blemmer PNPE series, Blemmer 43ANE -500, BLEMMER 70ANEP-550, etc., and Kyoeisha Chemical Co., Ltd. light ester MC, light ester 130MA, light ester 041MA, light acrylate BO-A, light acrylate EC-A, light acrylate MTG-A, light acrylate 130A, light Examples thereof include acrylate DPM-A, light acrylate P-200A, light acrylate NP-4EA, and light acrylate NP-8EA.

  In the present invention, a graft polymer using a so-called macromer can also be used. For example, it is described in “New Polymer Experimental Science 2, Polymer Synthesis / Reaction” edited by Polymer Society, Kyoritsu Publishing Co., Ltd. 1995. It is also described in detail in Yuya Yamashita's “Chemical Monomer Chemistry and Industry” IPC, 1989. Among the macromers, the useful molecular weight is in the range of 10,000 to 100,000, the preferred range is 10,000 to 50,000, and the particularly preferred range is in the range of 10,000 to 20,000. When the molecular weight is 10,000 or less, the effect cannot be exhibited, and when it is 100,000 or more, the polymerizability with the copolymerization monomer forming the main chain is deteriorated. Specifically, AA-6, AS-6S, AN-6S, etc. manufactured by Toagosei Co., Ltd. can be used.

  Needless to say, the present invention is not limited to the above specific examples. Only one type of polyoxyalkylene group-containing ethylenically unsaturated monomer may be used, or two or more types may be used simultaneously.

  Examples of other monomers that are specifically reacted with the above monomers include the following monomers.

Acrylic acid esters: methyl acrylate, ethyl acrylate, propyl acrylate, chloroethyl acrylate, 2-hydroxyethyl acrylate, trimethylolpropane monoacrylate, benzyl acrylate, methoxybenzyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate, etc.
Methacrylic acid esters: methyl methacrylate, ethyl methacrylate, propyl methacrylate, chloroethyl methacrylate, 2-hydroxyethyl methacrylate, trimethylolpropane monomethacrylate, benzyl methacrylate, methoxybenzyl methacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate, etc.
Acrylamides: acrylamide, N-alkylacrylamide (the alkyl group has 1 to 3 carbon atoms, such as methyl, ethyl, propyl), N, N-dialkylacrylamide, N-hydroxyethyl-N-methylacrylamide, N-2-acetamidoethyl-N-acetylacrylamide and the like. In addition, as alkyloxyacrylamide, methoxymethylacrylamide, butoxymethylacrylamide, etc.
Methacrylamides: methacrylamide, N-alkylmethacrylamide, N-hydroxyethyl-N-methylmethacrylamide, N-2-acetamidoethyl-N-acetylmethacrylamide, methoxymethylmethacrylamide, butoxymethylmethacrylamide, etc.
Allyl compounds: allyl esters (eg, allyl acetate, allyl caproate, allyl caprylate, allyl laurate, allyl palmitate, allyl stearate, allyl benzoate, allyl acetoacetate, allyl lactate, etc.), allyloxyethanol, etc.
Vinyl ethers: alkyl vinyl ethers (eg, hexyl vinyl ether, octyl vinyl ether, decyl vinyl ether, ethyl hexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, chloroethyl vinyl ether, 1-methyl-2,2-dimethylpropyl vinyl ether, 2-ethylbutyl vinyl ether, hydroxy Ethyl vinyl ether, diethylene glycol vinyl ether, dimethylaminoethyl vinyl ether, diethylaminoethyl vinyl ether, butylaminoethyl vinyl ether, benzyl vinyl ether, tetrahydrofurfuryl vinyl ether, etc.)
Vinyl esters: vinyl butyrate, vinyl isobutyrate, vinyl trimethyl acetate, vinyl diethyl acetate, vinyl valate, vinyl caproate, vinyl chloroacetate, vinyl dichloroacetate, vinyl methoxyacetate, vinyl butoxyacetate, vinyl lactate, vinyl -Β-phenylbutyrate, vinylcyclohexylcarboxylate, etc.
Dialkyl itaconates: dimethyl itaconate, diethyl itaconate, dibutyl itaconate, etc. Dialkyl esters of fumaric acid or monoalkyl esters: dibutyl fumarate and the like, crotonic acid, itaconic acid, acrylonitrile, methacrylonitrile, maleilonitrile, styrene and the like.

  When introducing an amide group, a C4-C22 linear or branched alkyl group, an aromatic group, or a heterocyclic group having 5 or more members, these functional groups are contained in the above-mentioned monomers or other monomers. A monomer to be selected may be selected. For example, 1-vinylimidazole or a derivative thereof can be used for introducing a heterocyclic group having 5 or more members. Furthermore, an isocyanate or epoxy group is introduced into the polymer in advance, and these are reacted with an alcohol or amine containing a linear or branched alkyl group, an aromatic group, or a 5- or more-membered heterocyclic group. Thus, various functional groups may be introduced into the polymer. In order to introduce isocyanate or epoxy, Karenz MOI (manufactured by Showa Denko) or Blemmer G (manufactured by NOF Corporation) can be used. Introducing a urethane bond is also preferable in the present invention.

  In the present invention, the isoelectric point of the polymer is preferably pH 6 or less. If a polymer having a high isoelectric point is used, as will be described later, when the silver halide grains are desalted by the aggregation precipitation method, the decomposition of the silver halide grains is promoted and the photographic performance is adversely affected. . Further, when silver halide fine particles are dispersed in a solvent, it is difficult to disperse unless the pH is raised, which is not preferable from the viewpoint of fogging. The isoelectric point of the polymer can be measured, for example, by isoelectric focusing or by measuring the pH after passing a 1% aqueous solution through a mixed bed column of cation and anion exchange resin.

  Various acidic groups can be introduced to lower the isoelectric point of the polymer. Examples include carboxylic acid and sulfonic acid groups. For the introduction of carboxylic acid, monomers of acrylic acid and methacrylic acid can be used, and a polymer containing methyl methacrylate or the like can be obtained by partial hydrolysis. In order to introduce the sulfonic acid group, styrene sulfonic acid or 2-acrylamido-2-methylpropane sulfonic acid can be used as a monomer, or can be introduced after the preparation of the polymer by various sulfation techniques. In particular, when a carboxylic acid is used, the solubility in a solvent is relatively high in an unneutralized state, and the property can be changed to water-soluble by neutralization or semi-neutralization, which is particularly preferable. Neutralization can be performed with sodium or potassium salts, and organic salts such as ammonia, monoethanolamine, diethanolamine, and triethanolamine may be used. Imidazoles, triazoles, and amidoamines can also be used.

  The polymerization can be carried out in the presence or absence of a solvent, but is preferably in the presence of a solvent from the viewpoint of workability. As the solvent, alcohols such as ethanol, isopropyl alcohol, n-butanol, iso-butanol, tert-butanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, methyl acetate, ethyl acetate, butyl acetate, Esters such as methyl lactate, ethyl lactate and butyl lactate, methyl 2-oxypropionate, ethyl 2-oxypropionate, propyl 2-oxypropionate, butyl 2-oxypropionate, methyl 2-methoxypropionate, 2- Monocarboxylic acid esters such as ethyl methoxypropionate, propyl 2-methoxypropionate, butyl 2-methoxypropionate, polar solvents such as dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, methyl cello Ethers such as butyl, cellosolve, butyl cellosolve, butyl carbitol, ethyl cellosolve acetate, propylene glycols such as propylene glycol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate, and Its esters, halogen solvents such as 1,1,1-trichloroethane and chloroform, ethers such as tetrahydrofuran and dioxane, aromatics such as benzene, toluene and xylene, and further perfluorooctane and perfluorotri-n-butylamine Fluorinated inert liquids and the like can be used, and any of these can be used.

  Depending on the polymerizability of each monomer, a dropping polymerization method in which a monomer and an initiator are added dropwise to a reaction vessel is also effective for obtaining a polymer having a uniform composition. By removing by column filtration, reprecipitation purification, solvent extraction, etc., unreacted monomers can be removed. Alternatively, low-boiling unreacted monomers can be removed by stripping.

  Except in the presence of a solvent, a polymer dispersion obtained by emulsion polymerization or suspension polymerization can also be used. These polymer preparation methods are described, for example, in “Synthetic Latex Chemistry (Muroichi Muroi, published by Kobunshi Shuppankai (1970))”.

  The molecular weight of the polymer is preferably 10,000 to 100,000, more preferably 10,000 to 50,000, in terms of polystyrene, as measured by mass average molecular weight and gel permeation chromatography (GPC). When the molecular weight is 10,000 or less, the protective colloid action on the silver halide grains is insufficient, the dispersibility cannot be obtained sufficiently, and the silver halide cannot be atomized. Further, when the molecular weight is too large, the viscosity of the dispersion may become too high, or silver halide grains may be aggregated.

  When the synthetic polymer of the present invention is an acrylic polymer, various techniques such as ionic polymerization and living polymerization can be used in addition to normal radical polymerization. For example, “Quarterly Chemical Review 18 Precision Polymerization (Person in charge of planning and editing of the Chemical Society of Japan; Takeo Shimizu, Shohei Inoue, Yasuhiko Shirota, Arata Tsuge, Toshinobu Higashimura)” can be referred to. All known materials can be applied to the polymerization initiator and the catalyst.

(Silver halide emulsion)
Next, a silver halide emulsion containing photosensitive silver halide grains using the polymer according to the present invention as a protective colloid will be described.

  In the photothermographic material of the present invention, the silver halide emulsion has an average particle size of 0.005 μm or more and 0.1 μm or less. Preferably, it is 0.005 μm or more and 0.08 μm or less. The average particle diameter here means the volume of the silver halide grains in the case where the silver halide grains are so-called normal crystals such as cubes and octahedrons, other than normal crystals, for example, spherical particles, rod-like grains, etc. The diameter when considering a sphere equivalent to the so-called sphere equivalent diameter. In the case where the silver halide grains are tabular grains, the diameter is the diameter when converted into a circular image having the same area as the projected area of the main surface. Obtained from the average of 1000 particles using an electron microscope.

  The optimum value of the coefficient of variation representing the particle size distribution is 0% to 30%, preferably 0% to 20%. Here, the variation coefficient of the particle size represents the degree of variation in the particle size, and is a value obtained by dividing the standard deviation of the diameter in terms of a circle in terms of the projected area of each particle measured with respect to 1000 particles using an electron microscope by the average particle size. Is the percentage display value.

  In the present invention, when a silver halide emulsion is prepared using gelatin, the silver halide emulsion is prepared even at a low temperature (for example, 10 ° C. or less) at which it cannot be prepared due to gelation and lack of fluidity of the solution. Thus, the Ostwald ripening and the like can be suppressed, and silver halide grains having a smaller grain size distribution than that of the prior art can be produced.

The addition amount of the photosensitive silver halide, the coating amount of silver per heat development material 1 m ^2, is preferably from 0.01 to 1.0 g / m ^2, is 0.01~0.4g / m ² More preferably, it is most preferable that it is 0.01-0.2 g / m < ² >.

In order to make the photosensitive silver halide grain size and addition amount the above-mentioned preferable conditions, the photographic performance is improved, the density at the same silver amount is improved, the haze (turbidity) is reduced, and the image quality is improved. When the grain size is less than 0.005 μm, the sensitivity is remarkably reduced, and when the silver halide grains are simply reduced in size, the silver halide grains themselves are the same as the silver halide grains. Aggregation occurs in the preparation step and the preparation step with the organic silver salt, the particle size distribution is remarkably widened, and haze (turbidity) cannot be sufficiently reduced. Moreover, when it exceeds 0.1 μm, haze (turbidity) becomes particularly remarkable. Further, if the applied silver amount is less than 0.01 g / m ² , the objective function as a heat developing material is insufficient, and sufficient photographic performance cannot be obtained, and if it exceeds 1.0 g / m ² , haze (turbidity) is obtained. It becomes a problem.

  The photosensitive silver halide used in the present invention may be silver chlorobromide, silver bromide, silver iodobromide, or silver iodochlorobromide. The total halogen composition is such that Br is 50% by mass or more. Something is preferable. If there is too much silver chloride, Ostwald ripening tends to proceed and the particle size tends to increase. On the other hand, if there is too much silver iodide, the sensitivity of the silver halide grains decreases, both of which are undesirable.

  The distribution of the halogen composition in the grains may be uniform, the halogen composition may be changed stepwise, or may be continuously changed. Further, silver halide grains having a core / shell structure can be preferably used. What is preferable as the structure is a structure having a halogen composition of 2 to 5 layers, and more preferably 2 to 4 layers of core / shell particles can be used. Further, a technique for localizing silver bromide, silver iodobromide, or silver iodide on the surface of silver chlorobromide grains can also be preferably used.

  In the photothermographic material of the present invention, a silver halide emulsion prepared from a polymer that is soluble in both water and an organic solvent may be added since the preparation of the organic silver salt. The photosensitive emulsion is prepared as a protective colloid in a water-based solvent in which water and an organic solvent are dissolved, and then dispersed in an organic solvent and mixed with an organic silver salt, that is, at least one organic silver By adding to a dispersion containing a salt, a solvent and a binder, it is preferably applied to a support together with necessary additives such as a silver ion reducing agent. In this case, these silver halide emulsions are preferably desalted and concentrated or dried by reducing the amount of water, so that they can be mixed with the organic silver salt even in a system mainly composed of an organic solvent. Dispersion is possible.

  As a method for forming the photosensitive silver halide, a method known in the art, for example, a method described in Research Disclosure No. 17029 in June 1978 and US Pat. No. 3,700,458 can be used. However, it is possible to use gelatin and polymers used in known examples, but it is possible to use all the particle production methods and apparatuses known so far by replacing part or all of them with the polymer of the present invention. it can.

  Specifically, a photosensitive silver halide is prepared by adding a silver supply compound and a halogen supply compound to the polymer solution of the present invention. In particular, a method of forming particles by adding a silver ion aqueous solution and a halide aqueous solution by a double jet is preferable.

(Silver halide, dope, sensitization, color sensitization)
Examples of the shape of the silver halide grains in the present invention include cubes, octahedrons, tabular grains, spherical grains, rod-shaped grains, potato-shaped grains, etc., but in the present invention, in particular, cubic grains, tabular grains. Particles are preferred. A preferable value as an average aspect ratio in the case of using tabular silver halide grains is 100: 1 to 2: 1, more preferably 50: 1 to 3: 1. Further, grains having rounded corners of silver halide grains can be preferably used. The surface index (Miller index) of the outer surface of the photosensitive silver halide grain is not particularly limited, but the spectral sensitizing efficiency when adsorbed by the spectral sensitizing dye is high and the proportion of the [100] plane is high. Is preferred. The ratio is preferably 50% or more, more preferably 65% or more, and still more preferably 80% or more. The ratio of the Miller index [100] plane is calculated by using the adsorption dependency between the [111] plane and the [100] plane in the adsorption of the sensitizing dye. Tani; Imaging Sci. 29, 165 (1985).

  In the present invention, the silver halide grains according to the present invention can contain an iridium compound. As the water-soluble iridium compound used in the present invention, various compounds can be used. For example, iridium (III) halide compounds, iridium (IV) halide compounds, iridium complex salts as ligands, halogens, amines Having oxalato, for example, hexachloroiridium (III) or (IV) complex salt, hexaammineiridium (III) or (IV) complex salt, trioxalatoiridium (III) or (IV) complex salt, hexacyanoiridium, pentachloro And nitrosyliridium. In the present invention, among these compounds, III-valent and IV-valent compounds can be used in any combination. These iridium compounds are used after being dissolved in water or an appropriate solvent, and are generally used in order to stabilize a solution of the iridium compound, that is, an aqueous hydrogen halide solution (for example, hydrochloric acid, odorous acid, fluorine, etc.). Acid) or an alkali halide (for example, KCl, NaCl, KBr, NaBr, etc.) can be used. Instead of using water-soluble iridium, it is also possible to add another silver halide grain previously doped with iridium and dissolve it at the time of silver halide preparation.

  In the present invention, the addition of the water-soluble iridium compound can be appropriately carried out at the time of producing the silver halide emulsion grains and at any time before coating the coating solution containing the silver halide emulsion. It is preferably added during emulsion formation and incorporated in the silver halide grains.

The amount of these water-soluble iridium compounds added is preferably in the range of 1 × 10 ⁻⁸ to 1 × 10 ⁻³ mol per mol of silver halide, more preferably in the range of 1 × 10 ^{−8 to} 5 × 10 ⁻⁵ mol. A range of 5 × 10 ^{−8 to} 5 × 10 ⁻⁶ mol is particularly preferable.

The photosensitive silver halide grain according to the present invention can contain, in addition to iridium, a metal or metal complex of Group VII or Group VIII (Group 7 to 10) of the other periodic table. Such a central metal is preferably rhodium, rhenium, ruthenium, or osmium. One kind of these metal complexes may be used, or two or more kinds of complexes of the same metal and different metals may be used in combination. The content is preferably in the range of 1 × 10 ⁻⁹ to 1 × 10 ⁻³ mol, more preferably in the range of 1 × 10 ⁻⁸ to 1 × 10 ⁻⁴ mol, with ^respect to 1 mol of silver. As a specific metal complex structure, a metal complex having a structure described in JP-A-7-225449 can be used.

  As the rhodium compound used in the present invention, a water-soluble rhodium compound can be used. For example, a rhodium (III) halide compound or a rhodium complex salt having a halogen, amines, oxalato, etc. as a ligand, such as hexachlororhodium (III) complex salt, pentachloroacorodium (III) complex salt, tetrachlorodia Examples thereof include a corodium (III) complex salt, a hexabromorhodium (III) complex salt, a hexaammine rhodium (III) complex salt, and a trizaratrodium (III) complex salt. These rhodium compounds are used by dissolving in water or a suitable solvent. In order to stabilize the rhodium compound solution, a generally used method is used, that is, an aqueous hydrogen halide solution (for example, hydrochloric acid, odorous acid, hydrofluoric acid). Etc.) or a method of adding an alkali halide (for example, KCl, NaCl, KBr, NaBr, etc.) can be used. Instead of using water-soluble rhodium, it is also possible to add another silver halide grain previously doped with rhodium at the time of silver halide preparation and dissolve it.

The addition amount of these rhodium compounds is preferably in the range of 1 × 10 ^{−8 to} 5 × 10 ⁻⁶ mol, particularly preferably 5 × 10 ⁻⁸ to 1 × 10 ⁻⁶ mol, per mol of silver halide.

  These compounds can be added as appropriate during the production of silver halide emulsion grains and at any stage prior to the application of a coating solution containing a silver halide emulsion. The silver halide grains are preferably incorporated into the silver halide grains.

  Rhenium, ruthenium and osmium used in the present invention are added in the form of water-soluble complex salts described in JP-A-63-2042, JP-A-1-285941, JP-A-2-20852, JP-A-2-20855, etc. Is done. Particularly preferred is a hexacoordination complex represented by the following formula.

[ML ₆ ] ^n-
Here, M represents Ru, Re, or Os, L represents a ligand, and n represents 0, 1, 2, 3, or 4.

  In this case, the counter ion has no significance and ammonium or alkali metal ions are used. Preferred ligands include halide ligands, cyanide ligands, cyanide oxide ligands, nitrosyl ligands, thionitrosyl ligands, and the like.

  Examples of specific complexes used in the present invention are shown below, but the present invention is not limited thereto.

[ReCl ₆ ] ³⁻ , [ReBr ₆ ] ³⁻ , [ReCl ₅ (NO)] ²⁻ , [Re (NS) Br ₅ ] ²⁻ , [Re (NO) (CN) ₅ ] ²⁻ , [Re (O) ₂ (CN) ₄ ] ³⁻ , [RuCl ₆ ] ³⁻ , [RuCl ₄ (H ₂ O) ₂ ] ⁻ , [RuCl ₅ (H ₂ O)] ²⁻ , [RuCl ₅ (NO)] ^2- , [RuBr ₅ (NS)] ²⁻ , [Ru (CO) ₃ Cl ₃ ] ²⁻ , [Ru (CO) Cl ₅ ] ²⁻ , [Ru (CO) Br ₅ ] ²⁻ , [OsCl ₆ ] ^3- , [OsCl ₅ (NO)] ²⁻ , [Os (NO) (CN) ₅ ] ²⁻ , [Os (NS) Br ₅ ] ²⁻ , [Os (O) ₂ (CN) ₄ ] ^{4 -}
The addition amount of these compounds is preferably in the range of 1 × 10 ⁻⁹ to 1 × 10 ⁻⁵ mol, particularly preferably 1 × 10 ⁻⁸ to 1 × 10 ⁻⁶ mol, per mol of silver halide.

  These compounds can be added as appropriate during the preparation of the silver halide emulsion grains and at any time before the coating solution containing the silver halide emulsion is applied. The silver halide grains are preferably incorporated into the silver halide grains.

  In order to add these compounds during the formation of silver halide grains and incorporate them into the silver halide grains, an aqueous solution dissolved together with the powder of the metal complex or NaCl or KCl is dissolved in the water solubility during the formation of the silver halide grains. A method of adding silver salt in a salt or water-soluble halide solution, a method of adding silver salt and a halide solution as a third solution when mixed simultaneously, and a method of preparing silver halide grains by a method of simultaneous mixing of three solutions, or halogen There is a method of charging a required amount of an aqueous solution of a metal complex into a reaction vessel during the formation of silver halide grains. In particular, a method of adding a powder or an aqueous solution dissolved together with NaCl and KCl to the water-soluble halide solution is preferable.

  In order to add to the grain surface, a required amount of an aqueous solution of a metal complex can be charged into the reaction vessel immediately after the formation of silver halide grains, during or after physical ripening, or at the time of chemical ripening.

  Furthermore, the silver halide grains used in the present invention may contain metal atoms such as cobalt, iron, nickel, chromium, palladium, platinum, gold, thallium, copper, lead. For cobalt, iron, chromium, and ruthenium compounds, hexacyano metal complexes can be preferably used. Specific examples include, but are not limited to, ferricyanate ions, ferrocyanate ions, hexacyanocobaltate ions, hexacyanochromate ions, and hexacyanoruthenate ions. The metal complex in the silver halide may be contained uniformly, may be contained in the core part at a high concentration, or may be contained in the shell part at a high concentration, and there is no particular limitation.

The content of the metal complex is preferably 1 × 10 ⁻⁹ to 1 × 10 ⁻⁴ mol per mol of silver halide. In order to contain the above metal complex, it can be added as a metal salt in the form of a single salt, a double salt, or a complex salt at the time of particle preparation.

  The photosensitive silver halide grains can be desalted by a water washing method known in the art, such as a noodle method, a coagulation precipitation method, or electrodialysis, but may be desalted by ultrafiltration. A polymer having a carboxylic acid in the present invention is suitable for the coagulation precipitation method and is preferable. When silver halide grains are grown using other polymers, the coagulation precipitation method may not be used, but even in such a case, desalting can be performed by ultrafiltration or the like.

  As the ultrafiltration method, for example, a method used for desalting / concentration of a silver halide emulsion known so far can be applied. Research Disclosure No. 10208 (1972), no. 13122 (1975) and no. 16351 (1977) and the like can be referred to. The pressure difference and flow rate that are important as operating conditions can be selected with reference to the characteristic curve described in Haruhiko Oya's “Membrane Utilization Technology Handbook” Koshobo Publishing (1978), p275, but it suppresses aggregation and fogging of particles. Therefore, it is necessary to find the optimum condition. There are two methods for replenishing the solvent that is lost due to membrane permeation: a constant volume method in which the solvent is continuously added and a batch method in which the solvent is intermittently added, but the desalting time is relatively short. The formula is preferred.

  As the solvent to be replenished, pure water obtained by ion exchange or distillation is used. However, in order to maintain the pH at a target value, a pH adjusting agent or the like may be mixed in the pure water. It may be added directly to the photosensitive organic silver salt.

  As for ultrafiltration membranes, flat plate type, spiral type, cylindrical type, hollow fiber type, hollow fiber type, etc., which are already incorporated as modules, include Asahi Kasei Co., Ltd., Daicel Chemical Co., Ltd., Toray Co., Ltd., and Nitto Co., Ltd. Although it is commercially available from Denko etc., a spiral type or a hollow fiber type is preferred from the viewpoint of the total membrane area and detergency. Moreover, it is preferable that the fraction molecular weight used as the parameter | index of the threshold value of the component which can permeate | transmit a film | membrane is 1/5 or less of the molecular weight of the polymer dispersing agent to be used.

  In the case of ultrafiltration, it may be one stage, but it is preferable to install a multistage ultrafiltration apparatus and continuously remove salts dissolved in the dispersion in the mixer and / or reaction vessel. . The multi-stage ultrafiltration apparatus is a combination of a plurality of thin tube-shaped ultrafiltration membranes such as VivaFlow 50 (trade name) manufactured by Sartorius AG in series and / or in parallel. Can be efficiently desalted and concentrated by passing the dispersion while adding. The flow rate of the dispersion liquid passing through the ultrafiltration membrane can be appropriately set depending on the concentration of the dispersion liquid, the type of polymer contained in the dispersion liquid, etc., but preferably 10 ml to 1000 ml, preferably 100 ml to 500 ml per one ultrafiltration membrane path. More preferred. The desalting / dehydration may be performed once or may be repeated a plurality of times. The addition and removal of water may be performed continuously or individually. The desalting / dehydration is performed so that the conductivity of the finally dehydrated water is preferably 300 μS / cm or less, more preferably 100 μS / cm or less. In this case, the lower limit of the conductivity is not particularly limited, but is usually about 5 μS / cm.

  The silver halide emulsion according to the present invention is preferably subjected to chemical sensitization. As chemical sensitization, known methods such as sulfur sensitization, gold sensitization, selenium sensitization, tellurium sensitization, and noble metal sensitization can be used. The silver halide grains of the present invention are prepared in an aqueous system and then redispersed in a solvent, but chemical sensitization may be performed in an aqueous system or after being redispersed in a solvent.

The sulfur sensitization preferably used in the present invention is usually performed by adding a sulfur sensitizer and stirring the silver halide emulsion for a predetermined time. As the sulfur sensitizer, a known compound can be used. For example, thiosulfate, thioureas, thiazoles, rhodanines and the like can be used. Preferred sulfur compounds are thiosulfate and thiourea compounds. The addition amount of the sulfur sensitizer is not uniform depending on various conditions such as pH at the time of chemical ripening, temperature, and the size of silver halide grains, but 1 × 10 ⁻⁷ to 1 × 10 10 per mol of silver halide. ^-2 mol, more preferably 1 × 10 ⁻⁵ to 1 × 10 ⁻³ mol.

  A known selenium compound can be used as the selenium sensitizer used in the present invention. That is, it is usually carried out by adding an unstable or non-labile selenium compound and stirring the silver halide emulsion for a certain time. As the unstable selenium compound, for example, compounds described in JP-B Nos. 44-15748, 43-13489, JP-A-4-25832, 4-109240, 4-324855 and the like can be used. . In particular, it is preferable to use compounds represented by the general formulas (VIII) and (IX) described in JP-A-4-324855.

  The tellurium sensitizer used in the present invention is a compound that generates silver telluride presumed to be a sensitization nucleus on the surface or inside of a silver halide grain. The silver telluride formation rate in the silver halide emulsion can be tested, for example, by the method described in JP-A-5-313284. Examples of tellurium sensitizers include diacyl tellurides, bis (oxycarbonyl) tellurides, bis (carbamoyl) tellurides, diacyl tellurides, bis (oxycarbonyl) ditellurides, bis (carbamoyl) ditellurides, P = Te-bonded compounds, tellurocarboxylates, Te-organyl tellurocarboxylates, di (poly) tellurides, tellurides, tellurols, telluroacetals, tellurosulfonates, compounds having P-Te bonds Te-containing heterocycles, tellurocarbonyl compounds, inorganic tellurium compounds, colloidal tellurium, and the like can be used. Specifically, U.S. Patent Nos. 1,623,499, 3,320,069, 3,772,031, British Patent Nos. 235,211, 1,121,496, 1,295,462, 1,396,696, Canadian Patent 800,958, JP-A-4-204640, Patents 2654722, 2699029, 2811257, Journal of Chemical Society Chemical Communication (J. Chem. Soc. Chem. Commun.), 635 (1980), ibid, 1102 (1979), ibid, 645 (1979), Journal of Chemical Society Parkin Transaction 1 (J. Chem. Soc. Perkin. Trans. 1), 2191 (1 80), S. Edited by S. Patai, The Chemistry of Organic Selenium and Tellurium Compounds, Vol., The Chemistry of Organic Serenium and Tellunium Compounds. 1 (1986), Vol. 2 (1987) can be used. In particular, compounds represented by the general formulas (II), (III) and (IV) in JP-A-5-313284 are preferred.

The amount of selenium and tellurium sensitizers used in the present invention is not uniform depending on the silver halide grains used, chemical ripening conditions, etc., but generally 1 × 10 ⁻⁸ to 1 × per mole of silver halide. 10 ⁻² mol, preferably about 1 × 10 ⁻⁷ to 1 × 10 ⁻³ mol is used. The conditions for chemical sensitization in the present invention are not particularly limited, but the pH is 5 to 8, the pAg is 6 to 11, preferably 7 to 10, and the temperature is 40 to 95 ° C, preferably 45. ~ 85 ° C.

  As the gold sensitizer used for gold sensitization to the silver halide emulsion according to the present invention, the gold oxidation number may be either +1 or +3, and a gold compound usually used as a gold sensitizer is used. be able to. Typical examples include chloroauric acid, potassium chloroaurate, auric trichloride, potassium auric thiocyanate, potassium iodoaurate, tetracyanoauric acid, ammonium aurothiocyanate, pyridyltrichlorogold and the like.

The amount of the gold sensitizer added varies depending on various conditions, but is generally 1 × 10 ⁻⁷ mol or more, 1 × 10 ⁻³ mol or less, more preferably 1 × 10 ⁻⁶ mol or more, per mol of silver halide. 5 × 10 ⁻⁴ mol or less.

  The silver halide emulsion according to the present invention can be used in combination with gold sensitization and other chemical sensitization. When used in combination with gold sensitization, for example, sulfur sensitization and gold sensitization are used. Method, selenium sensitization method and gold sensitization method, sulfur sensitization method and selenium sensitization method and gold sensitization method, sulfur sensitization method and tellurium sensitization method and gold sensitization method, sulfur sensitization method and selenium sensitization Method, tellurium sensitization and gold sensitization are preferred.

  In the silver halide emulsion used in the present invention, a cadmium salt, a sulfite salt, a lead salt, a thallium salt or the like may coexist in the process of silver halide grain formation or physical ripening.

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

  A thiosulfonic acid compound may be added to the silver halide emulsion according to the present invention by the method shown in European Patent Publication No. 293,917.

  The photosensitive silver halide grain according to the present invention may be spectrally sensitized by adsorbing a spectral sensitizing dye. As spectral sensitizing dyes, cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, holopolar cyanine dyes, styryl dyes, hemicyanine dyes, oxonol dyes, hemioxonol dyes, and the like can be used. For example, JP-A-63-159841, JP-A-60-140335, JP-A-63-231437, JP-A-63-259651, JP-A-63-304242, JP-A-63-15245, U.S. Pat. The sensitizing dyes described in US Pat. Nos. 4,740,455, 4,741,966, 4,751,175, and 4,835,096 can be used. Useful sensitizing dyes used in the present invention are described in, for example, the literature described or cited in RD17643IV-A (December 1978, p.23) and 18431X (August 1978, p.437). Yes. In particular, it is preferable to use a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of various laser imagers and scanner light sources. For example, compounds described in JP-A Nos. 9-34078, 9-54409, and 9-80679 are preferably used.

  The silver halide emulsion contained in the heat-developable material according to the present invention may be one kind or two or more kinds (for example, those having different average grain sizes, those having different halogen compositions, those having different crystal habits, chemical Those having different sensitization conditions) may be used in combination.

  In the present invention, in order to control gradation characteristics (gamma), it is preferable to use a plurality of types of silver halide emulsions, and the grain size, shape, halogen composition, sensitizing dye adsorption amount, Multiple types of silver halide emulsions can be obtained by controlling the amount of the chemical sensitizer. As the silver halide emulsion type to be used, 2 to 4 types, preferably 2 to 3 types, are preferably mixed or used as separate layers. The difference in sensitivity between the silver halide emulsions is preferably at least 0.2 LogE, and more preferably at least 0.3 LogE. “Log E” is an index representing sensitivity, and after exposure is performed through an optical wedge, the exposure amount (E) constituting the horizontal axis in a characteristic curve in which the vertical axis indicates density and the horizontal axis indicates exposure amount. ) Is a logarithmic value.

  As technologies relating to these, JP-A-57-119341, JP-A-53-106125, JP-A-47-3929, JP-A-48-55730, JP-A-46-5187, JP-A-50-73627 and JP-A-57-150841 are disclosed. Can be mentioned. The upper limit of the sensitivity difference is not particularly limited, but is a difference of about 1.0 LogE at maximum.

  Thus, in the present invention, the silver halide emulsion is preferably desalted, concentrated, or dried. Concentration can be performed, for example, by using an evaporator under reduced pressure. Below conductivity, it is not necessary to be completely dried, but in an organic solvent system, it may be mixed with an organic silver salt and, in particular, may be a range that does not cause separation, aggregation or the like of the polymer. Preferably, the water content of the photosensitive emulsion is 5% or less, preferably 1% or less.

  Further, using the silver halide, the dispersion degree (electron microscope image is used for photosensitive silver halide grains having a particle diameter measured from the exposure direction of the photosensitive material of 0.005 μm or more and 0.1 μm or less. It is preferable that the standard deviation / average value of the cell area centering on each particle obtained by the expansion method is 80% or less.

  In the present invention, the degree of dispersion can be specifically determined by the following procedure. First, the photosensitive layer coated on the support is attached to an appropriate holder with an adhesive, and an ultrathin slice having a thickness of 0.1 to 0.2 μm is used in a direction substantially parallel to the support surface using a diamond knife. Is made. At this time, the upper and lower ends of the photosensitive layer are observed with an optical microscope to confirm that the cutting is performed substantially parallel to the support surface, that is, the cutting angle is 1 degree or less.

  The prepared ultrathin slice was supported on a copper mesh, transferred onto a carbon film that had been hydrophilized by glow discharge, and cooled to −130 ° C. or lower with liquid nitrogen, while being subjected to a transmission electron microscope (hereinafter referred to as TEM). Thus, a bright field image is observed at a magnification of 5,000 to 40,000, and the image is quickly recorded on a film, an imaging plate, a CCD camera or the like. At this time, it is preferable to appropriately select a portion where the section is not torn or slack as an observed visual field.

  As the carbon film, it is preferable to use a film supported by an organic film such as a very thin collodion or form bar, and more preferably, the carbon film is formed on a rock salt substrate and dissolved and removed, or the organic film is formed of an organic film. It is a carbon-only film obtained by solvent and ion etching.

  The acceleration voltage of TEM is preferably 80 to 400 kV, particularly preferably 80 to 200 kV.

  In addition, for details of electron microscope observation techniques and sample preparation techniques, see “The Japan Electron Microscope Society Kanto Branch / Medical and Biological Electron Microscopy” (Maruzen), “The Japan Electron Microscope Society Kanto Branch / Electron Microscope Biological Samples” "Manufacturing method" (Maruzen) can be referred to respectively.

  A TEM image recorded on a suitable medium is preferably decomposed into at least 1024 pixels × 1024 pixels, preferably 2048 pixels × 2048 pixels or more, and image processing by a computer is performed.

  In order to perform image processing, an analog image recorded on a film is preferably converted into a digital image by a scanner or the like, and shading correction, contrast / edge enhancement, etc. are performed as necessary. Thereafter, a histogram is prepared, and a portion corresponding to photosensitive silver halide that is 0.005 μm or more and 0.1 μm or less is extracted by binarization processing. Inevitably, the aggregated particles are cut by an appropriate algorithm, and particles having an equivalent circle diameter (HEYWOOD) of less than 0.005 μm are deleted (Eliminate). Next, the center point of each particle is obtained (SHLINK), and each pixel is expanded (EXTEND) by the center point until it touches each other to form a cell around the center point. At this time, the cell that has taken the measurement frame is deleted (EDGEPROCESS REJECT), and the equivalent circle diameter (HEYWOOD) of each cell is obtained. Similarly, an average value and a standard deviation are calculated from values obtained for at least 500, preferably 1000 or more cells, and the degree of dispersion is obtained by the following equation.

Dispersity = (standard deviation of equivalent circle diameter of cell) / (average value of equivalent circle diameter of cell) × 100
When performing the measurement according to the above procedure, it is preferable to sufficiently perform the length correction (scale correction) per pixel and the two-dimensional distortion of the measurement system in advance using a standard sample. Uniform latex particles (DULP) marketed by US Dow Chemical Company are suitable as the standard sample, and polystyrene particles having a coefficient of variation of less than 10% for a particle size of 0.1 to 0.3 μm are used. Specifically, a lot having a particle size of 0.212 μm and a standard deviation of 0.0029 μm is available.

  The details of the image processing technology can be referred to "Hiroshi Tanaka image processing applied technology (Industry Research Committee)", and the image processing program or device is not particularly limited as long as the above operation is possible, An example is Lulex-III manufactured by Nireco.

  The method for improving the degree of dispersion of the photosensitive silver halide is not particularly limited, but it is effective to optimize various conditions at the time of mixing with an organic silver soap and / or at the time of dispersing a dry soap.

  The average grain size of the silver halide grains contained in the silver halide emulsion using as a dispersant a polymer that is soluble in both water and an organic solvent is 0.005 μm or more and 0.1 μm or less, and the grain size is By using a silver halide emulsion having a coefficient of variation of 0% or more and 30% or less, such a photothermographic material can be obtained, and a photothermographic material having low fog and high covering power (CP) can be obtained. .

  The photothermographic material of the present invention contains a reducing agent. Examples of suitable reducing agents include those described in U.S. Pat. Nos. 3,589,903 and 4,021,249 or British Patent 1,486,148 and JP-A-51-51933. -36110, 50-116023, 52-84727 or JP-B-51-35727, for example, 2,2'-dihydroxy-1,1'-binaphthyl, 6, Bisnaphthols described in US Pat. No. 3,672,904 such as 6′-dibromo-2,2′-dihydroxy-1,1′-binaphthyl, and further, for example, 4-benzenesulfonamidophenol, Such as 2-benzenesulfonamidophenol, 2,6-dichloro-4-benzenesulfonamidophenol, 4-benzenesulfonamidonaphthol, etc. It can be used sulfonamidophenols or sulfonamidonaphthols, such as described in national patent 3,801,321. Particularly preferred reducing agents are bisphenol compounds (particularly hindered phenols linked by a branched alkylene chain).

  Preferred typical specific examples are shown below, but the present invention is not limited thereto.

The amount of the reducing agent including the compounds represented by the above specific examples is preferably 1 × 10 ⁻² to 10 mol, particularly preferably 1 × 10 ^{−2 to} 1.5 mol, per mol of silver.

  In the present invention, the reducing agent (silver ion reducing agent) and a compound which is a bisphenol derivative represented by the following general formula (A ′) can be used in combination. By using the bisphenol compound represented by the general formula (A ') in combination with a reducing agent having another different chemical structure, performance deterioration due to fog generation during storage of the photothermographic material of the present invention and after heat development It is possible to unexpectedly suppress color tone deterioration and the like during storage of silver images.

In the bisphenol compound represented by the general formula (A ′), Z represents a —S— group or a —C (R ₃₃ ) (R ₃₃ ′) — group, and R ₃₃ and R ₃₃ ′ are each a hydrogen atom or a substituted group. Represents a group. Examples of the substituent represented by R ₃₃ and R ₃₃ ′ include an alkyl group (for example, methyl, ethyl, propyl, isopropyl, cyclopropyl, butyl, isobutyl, sec-butyl, t-butyl, cyclohexyl, 1-methyl). -Each group such as cyclohexyl), an alkenyl group (for example, each group such as vinyl, propenyl, butenyl, pentenyl, isohexenyl, cyclohexenyl, butenylidene, isopentylidene, etc.), an alkynyl group (each group such as ethynyl, propynylidene), In addition to aryl groups (eg, phenyl, naphthyl, etc.), heterocyclic groups (eg, furyl, thienyl, pyridyl, tetrahydrofuranyl, etc.), halogen atoms, hydroxyl, alkoxy, aryloxy, acyloxy, sulfonyl Oxy, nitro, amino, acylami , Sulfonylamino, sulfonyl, carboxy, alkoxycarbonyl, aryloxycarbonyl, carbamoyl, sulfamoyl, cyano, each group sulfo and the like. R ₃₃ and R ₃₃ ′ are preferably a hydrogen atom or an alkyl group.

R ₃₁ , R ₃₂ , R ₃₁ ′ and R ₃₂ ′ each represent a substituent, and examples of the substituent include the same groups as the substituents represented by R ₃₃ and R ₃₃ ′. R ₃₁ , R ₃₂ , R ₃₁ ′, and R ₃₂ ′ are preferably an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, and the like, and an alkyl group is more preferable. Examples of the substituent on the alkyl group include the same groups as the substituents represented by R ₃₃ and R ₃₃ ′. R ₃₁ , R ₃₂ , R ₃₁ ′ and R ₃₂ ′ are more preferably tertiary alkyl groups such as t-butyl, t-amyl, t-octyl and 1-methylcyclohexyl.

X ₃₁ and X ₃₁ ′ each represent a hydrogen atom or a substituent, and examples of the substituent include the same groups as the substituents represented by R ₃₃ and R ₃₃ ′.

  Specific examples of the bisphenol compound represented by the general formula (A ′) are shown below, but are not limited thereto.

  As a method for adding the compound represented by the general formula (A ′), these layers may be dispersed in water or dissolved in an organic solvent to be contained in a photosensitive layer coating solution or an adjacent layer coating solution. Can be contained. As the organic solvent, alcohols such as methanol and ethanol, ketones such as acetone and methyl ethyl ketone, and aromatics such as toluene and xylene can be arbitrarily selected.

The amount of the compound represented by the general formula (A ′) is suitably in the range of 1 × 10 ⁻² to 10 mol, preferably 8 × 10 ^{−2 to} 1.5 mol, per mol of silver.

  The photothermographic material of the present invention preferably contains an antifoggant. Mercury ions are known as the most effective antifoggants. The use of a mercury compound as an antifoggant in a photothermographic material is disclosed, for example, in US Pat. No. 3,589,903. However, the use of mercury compounds is environmentally undesirable.

  Examples of non-mercury antifoggants include antifoggants as disclosed in US Pat. Nos. 4,546,075, 4,452,885 and JP-A-59-57234. Agents are preferred.

Particularly preferred non-mercury antifoggants include compounds such as those disclosed in US Pat. Nos. 3,874,946 and 4,756,999, —C (X ₁ ) (X ₂ ) ( X ₃ ) (wherein X ₁ and X ₂ each represent a halogen atom, and X ₃ represents a hydrogen atom or a halogen atom), a heterocyclic compound having one or more substituents. As examples of suitable antifoggants, compounds described in paragraph numbers [0030] to [0036] of JP-A-9-288328 are preferably used. Another preferred antifoggant is a compound described in paragraph numbers [0062] to [0063] of JP-A-9-90550. Still other suitable antifoggants are disclosed in US Pat. No. 5,028,523 and European Patent Nos. 600,587, 605,981, 631,176, etc. A compound or the like can be used.

  To the photothermographic material of the invention, it is preferable to add a color tone for the purpose of improving the silver tone after development. The toning agent has a function of making the resulting silver image dark, particularly black, by participating in the redox reaction between the organic silver salt and the reducing agent. Examples of suitable toning agents for use in the present invention are disclosed in Research Disclosure No. 17029 and include:

  Imides (eg, phthalimide); cyclic imides, pyrazolin-5-ones, and quinazolinones (eg, succinimide, 3-phenyl-2-pyrazolin-5-one, 1-phenylurazole, quinazoline, and 2,4- Thiazolidinedione); naphthalimides (eg, N-hydroxy-1,8-naphthalimide); cobalt complexes (eg, hexamine trifluoroacetate of cobalt), mercaptans (eg, 3-mercapto-1,2,4-triazole) N- (aminomethyl) aryl dicarboximides (eg, N- (dimethylaminomethyl) phthalimide); combinations of blocked pyrazoles, isothiuronium derivatives and certain photobleaching agents (eg, N, N'-F A combination of Samethylene (1-carbamoyl-3,5-dimethylpyrazole), 1,8- (3,6-dioxaoctane) bis (isothiuronium trifluoroacetate), and 2- (tribromomethylsulfonyl) benzothiazole ); Merocyanine dyes (e.g. 3-ethyl-5- (3-ethyl-2-benzothiazolinylidene) -benzothiazolinylidene-1-methylethylidene-2-thio-2,4-oxazolidinedione); Phthalazinone, phthalazinone derivatives or metal salts of these derivatives (eg, 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxyphthalazinone, and 2,3-dihydro-1,4- Phthalazinedione); combinations of phthalazinone and sulfinic acid derivatives (eg 6-chloro Tarazinone + sodium benzenesulfinate or 8-methylphthalazinone + sodium p-trisulfonate); phthalazine + phthalic acid combination; phthalazine (including phthalazine adduct) and maleic anhydride, and phthalic acid, 2,3 A combination with at least one compound selected from naphthalenedicarboxylic acid or o-phenylene acid derivatives and anhydrides thereof (eg phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic anhydride); quinazoline Diones, benzoxazines, naphthoxazine derivatives; benzoxazine-2,4-diones (eg, 1,3-benzoxazine-2,4-dione); pyrimidines and asymmetric-triazines (eg, 2,4- Dihydroxypyrimidine) and tetraazapenta Len derivatives (eg 3,6-dimercapto-1,4-diphenyl-1H, 4H-2,3a, 5,6a-tetraazapentalene). Preferable colorant is phthalazone or phthalazine.

  Examples of the photothermographic material of the invention include those disclosed in JP-A Nos. 63-159841, 60-140335, 63-231437, 63-259651, 63-304242 and 63-15245. Each publication, U.S. Pat. Nos. 4,639,414, 4,740,455, 4,741,966, 4,751,175, 4,835,096 Sensitizing dyes can be used.

  Useful sensitizing dyes used in the present invention are described or cited in, for example, Research Disclosure No. 17643IV-A (December 1978, p.23), 18431 (August 1979, p.437). It is described in the literature. In particular, a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of various scanner light sources can be advantageously selected. For example, compounds are preferably used as described in JP-A Nos. 9-34078, 9-54409, and 9-80679.

Sensitizing dyes may be used alone, or two or more kinds of sensitizing dyes may be used in combination. When the sensitizing dye is used alone or in combination, the total amount is 1 × 10 ^{−6 to} 5 × 10 ⁻³ mol, preferably 1 × 10 ^{−5 to} 2.5 × 10, per mol of silver halide. ^-3 mol, more preferably 4 x 10 ^-5 to 1 x 10 ^-3 mol in the silver halide emulsion. When two or more sensitizing dyes are used in combination, they can be contained in the silver halide emulsion in an arbitrary ratio.

  A combination of sensitizing dyes is often used for the purpose of supersensitization. Along with the sensitizing dye, the emulsion itself may contain a dye having no spectral sensitizing action or a substance that does not substantially absorb visible light and exhibits supersensitization.

  In the present invention, a mercapto compound, a disulfide compound, and a thione compound can be contained in order to control (suppress or promote) development, to improve spectral sensitization efficiency, and to improve 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, the heteroaromatic ring is benzimidazole, naphthimidazole, benzothiazole, naphthothiazole, benzoxazole, naphthoxazole, benzoselenazole, benzotelrazole, imidazole, oxazole, pyrazole, triazole, thiadiazole, tetrazole, triazine, pyrimidine, pyridazine , Pyrazine, pyridine, purine, quinoline or quinazolinone. This heteroaromatic ring has, for example, a halogen atom (for example, Br, Cl), a hydroxyl group, an amino group, a carboxy group, an alkyl group (for example, one or more carbon atoms, preferably 1 to 4 carbon atoms) And an alkoxy group (for example, one having one or more carbon atoms, preferably one having 1 to 4 carbon atoms). Mercapto-substituted heteroaromatic compounds include 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole, 2-mercapto-5-methylbenzothiazole, 3-mercapto-1,2,4-triazole, 2 -Mercaptoquinoline, 8-mercaptopurine, 2,3,5,6-tetrachloro-4-pyridinethiol, 4-hydroxy-2-mercaptopyrimidine, 2-mercapto-4-phenyloxazole, and the like. It is not limited.

  In the present invention, it is preferable to contain a matting agent on the photosensitive layer side, and it is preferable to dispose the matting agent on the surface of the photothermographic material in order to prevent damage to the image after heat development. It is preferable to contain 0.5-30% by mass ratio with respect to the total binder on the photosensitive layer side.

  Further, when a non-photosensitive layer is provided on the opposite side of the photosensitive layer with the support interposed, it is preferable that at least one layer on the non-photosensitive layer side contains a matting agent, and the photothermographic material is not slippery and prevents fingerprint adhesion. Therefore, it is preferable to dispose a matting agent on the surface of the photothermographic material, and the matting agent should be contained in a mass ratio of 0.5 to 40% with respect to all binders on the layer opposite to the photosensitive layer side. Is preferred.

  The material of the matting agent used in the present invention may be either organic or inorganic. Examples of inorganic substances include silica described in Swiss Patent No. 330,158 and the like, glass powder described in French Patent No. 1,296,995 and the like, and British Patent No. 1,173,181. Alkaline earth metals or carbonates such as cadmium and zinc described in the book can be used as the matting agent. Examples of organic substances include starch described in US Pat. No. 2,322,037 and the like, starch derivatives described in Belgian Patent 625,451 and British Patent 981,198, and the like. No. 44-3643, etc., polyvinyl alcohol described in Swiss Patent No. 330,158, etc., polymethacrylate described in US Pat. No. 3,079,257, etc., polyacrylonitrile described in US Pat. An organic matting agent such as polycarbonate described in Japanese Patent No. 3,022,169 can be used.

  The shape of the matting agent may be either a regular shape or an irregular shape, but is preferably a regular shape, and a spherical shape is preferably used. The size of the matting agent is represented by a diameter when the volume of the matting agent is converted into a sphere. The particle size of the matting agent indicates the diameter converted into a spherical shape. The matting agent used in the present invention preferably has an average particle size of 0.5 to 10 μm, more preferably 1.0 to 8.0 μm. The coefficient of variation of the particle size distribution is preferably 50% or less, more preferably 40% or less, and particularly preferably 30% or less. Here, the variation coefficient of the particle size distribution is a value represented by the following equation.

(Standard deviation of particle size) / (Average value of particle size) × 100
The matting agent can be contained in any constituent layer, but is preferably a constituent layer other than the photosensitive layer, and more preferably the outermost layer as viewed from the support.

  The method for adding the matting agent may be a method in which the matting agent is dispersed and applied in advance, or a method in which the matting agent is sprayed after the coating solution is applied and before the drying is completed may be used. When a plurality of types of matting agents are added, both methods may be used in combination.

  In the present invention, a conductive compound such as a metal oxide and / or a conductive polymer can be included in the constituent layers in order to improve the chargeability. These may be contained in any layer, but are preferably contained in the undercoat layer, the backing layer, the layer between the photosensitive layer and the undercoat, and the like. In the present invention, the conductive compounds described in US Pat. No. 5,244,773, columns 14 to 20 are preferably used.

  Various additives may be added to any of the photosensitive layer, the non-photosensitive layer, and other constituent layers. In addition to those described above, for example, surfactants, antioxidants, stabilizers, plasticizers, ultraviolet absorbers, coating aids and the like may be used in the photothermographic material of the invention. As these additives and other additives, compounds described in Research Disclosure No. 17029 (June 1978, p. 9-15) can be preferably used.

  Binders suitable for the photothermographic material of the present invention are transparent or translucent and generally colorless, and include natural polymers, synthetic polymers and copolymers, and other film-forming media such as gelatin, gum arabic, polyvinyl alcohol, hydroxy Ethyl cellulose, cellulose acetate, cellulose acetate butyrate, polyvinyl pyrrolidone, casein, starch, polyacrylic acid, polymethyl methacrylate, polymethacrylic acid, polyvinyl chloride, copoly (styrene-maleic anhydride), copoly (styrene-acrylonitrile), copoly (Styrene-butadiene), polyvinyl acetals, such as polyvinyl formal, polyvinyl butyral, polyesters, polyurethanes, phenoxy resins, polyvinylidene chloride, polyepoxy S, polycarbonates, polyvinyl acetates, cellulose esters, there is a polyamide or the like, or a non-hydrophilic or hydrophobic. However, among these binders, water-insoluble polymers such as cellulose acetate, cellulose acetate butyrate, and polyvinyl butyral are particularly preferable, and polyvinyl butyral is particularly preferable.

  Further, in order to protect the surface of the photothermographic material or prevent scratches, a non-photosensitive layer can be provided outside the photosensitive layer. The binder used for these non-photosensitive layers may be the same as or different from the binder used for the photosensitive layer.

In the present invention, the binder amount of the photosensitive layer is preferably 1.5 to 10 g / m ² in order to increase the speed of heat development. More preferably, it is 1.7-8 g / m < ² >. If it is less than 1.5 g / m ² , the density of the unexposed area is significantly increased and may not be used.

  The support used in the photothermographic material of the present invention is transparent and is a plastic film (for example, polyethylene terephthalate, polycarbonate, polyimide, nylon, cellulose triacetate, polyethylene naphthalate) in order to prevent deformation of the image after development processing. Is preferred.

  Among them, preferable examples of the support include polyethylene terephthalate (hereinafter abbreviated as PET) and a plastic (hereinafter abbreviated as SPS) support including a styrene polymer having a syndiotactic structure. The thickness of the support is about 50 to 300 μm, preferably 70 to 180 μm. A heat-treated plastic support can also be used. Examples of the plastic to be used include the plastics described above. The heat treatment of the support is a temperature 30 ° C. or more higher than the glass transition point of the support, preferably 35 ° C. or more after the formation of these supports and before the photosensitive layer is applied. Preferably, the heating is performed at a temperature that is 40 ° C. or higher.

  PET is composed of polyethylene terephthalate as a component of polyester. However, in addition to polyethylene terephthalate, terephthalic acid, naphthalene-2,6-dicarboxylic acid, isophthalic acid, butylene dicarboxylic acid, 5-sodium sulfoisophthalic acid, It may be a polyester in which a modified polyester component such as adipic acid or the like and ethylene glycol, propylene glycol, butanediol, cyclohexanedimethanol or the like as a glycol component is contained in an amount of 10 mol% or less of the total polyester.

  Unlike ordinary polystyrene (atactic polystyrene), SPS is a sterically regular polystyrene. The regular stereoregular structure part of SPS is called a racemo chain, and it is preferable that there are more regular parts such as 2-chain, 3-chain, 5-chain or more, and the racemo chain is 85% or more in 2 chains. It is preferable that it is 75% or more in 3 chains, 50% or more in 5 chains, and 30% or more in more chains. The polymerization of SPS can be carried out according to the method described in JP-A-3-131833.

  Known methods can be used for the film forming method and the undercoating method for the support used in the photothermographic material of the present invention, and preferably paragraph numbers [0030] to [0070] of JP-A-9-50094. Using the method described in.

  The photothermographic material of the present invention forms a photographic image by heat development processing and suppresses a reducible silver source (organic silver salt), a photosensitive silver halide, a reducing agent, and, if necessary, the color tone of silver. The photothermographic material preferably contains a toning agent to be dispersed in a normal (organic) binder matrix.

  The photothermographic material of the present invention is stable at room temperature, but is developed by heating to a high temperature (for example, 80 to 140 ° C.) after exposure. By heating, silver is generated through an oxidation-reduction reaction between an organic silver salt (functioning as an oxidizing agent) and a reducing agent. This redox reaction is promoted by the catalytic action of the latent image generated in the silver halide upon exposure. The silver produced by the reaction of the organic silver salt in the exposed areas provides a black image that contrasts with the unexposed areas and forms an image. This reaction process proceeds without supplying a treatment liquid such as water from the outside.

  The photothermographic material of the present invention has at least one photosensitive layer on a support. Although only the photosensitive layer may be formed on the support, it is preferable to form at least one non-photosensitive layer on the photosensitive layer. In order to control the amount of light passing through the photosensitive layer or the wavelength distribution, a filter layer may be formed on the same side as or opposite to the photosensitive layer, or a dye or pigment may be contained in the photosensitive layer. As the dye, a compound described in JP-A-8-201959 is preferable. The photosensitive layer may be a plurality of layers, or a high-sensitivity layer and a low-sensitivity layer may be provided for adjusting the gradation, and these may be combined. Various additives may be added to any of the photosensitive layer, the non-photosensitive layer, and other forming layers. As described above, for example, surfactants, antioxidants, stabilizers, plasticizers, ultraviolet absorbers, coating aids and the like may be used in the photothermographic material of the invention. The non-photosensitive layer preferably contains the binder and matting agent, and may further contain a polysiloxane compound, a slipping agent such as wax or liquid paraffin.

A preferable total silver amount of the photothermographic material is 0.5 to 1.5 g / m ² .

  Details of the photothermographic material are as described above, for example, U.S. Pat. Nos. 3,152,904, 3,457,075, and D.I. Morgan, “Dry Silver Photographic Materials” (Handbook of Imaging Materials, Marcel Dekker, Inc., page 48, 1991) and the like. Among them, the present invention is characterized in that an image is formed by thermally developing a photothermographic material at 80 to 140 ° C. and fixing is not performed. Therefore, the silver halide and the organic silver salt remaining in the unexposed portion remain as they are in the photothermographic material without being removed.

  In the present invention, it is preferable that the optical transmission density of the photothermographic material containing a support at 400 nm after heat development is 0.2 or less. A more preferable value of the optical transmission density is 0.02 or more and 0.2 or less. If it is less than 0.02, the sensitivity is so low that it cannot be used.

  Examples of the solvent used in the present invention include ketones such as acetone, isophorone, ethyl amyl ketone, methyl ethyl ketone, and methyl isobutyl ketone. Examples of alcohols include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, diacetone alcohol, cyclohexanol, and benzyl alcohol. Examples of glycols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and hexylene glycol. Examples of ether alcohols include ethylene glycol monomethyl ether and diethylene glycol monoethyl ether. Examples of ethers include ethyl ether, dioxane, isopropyl ether and the like. Examples of the esters include ethyl acetate, butyl acetate, amyl acetate, isopropyl acetate and the like. Examples of hydrocarbons include n-pentane, n-hexane, n-heptane, cyclohexane, benzene, toluene, xylene and the like. Examples of chlorides include methyl chloride, methylene chloride, chloroform, dichlorobenzene and the like. Examples of amines include monomethylamine, dimethylamine, triethanolamine, ethylenediamine, and triethylamine. Other examples include water, formamide, dimethylformamide, nitromethane, pyridine, toluidine, tetrahydrofuran, and acetic acid.

  However, it is not limited to these. These solvents can be used alone or in combination of several kinds.

  The content of the solvent in the photothermographic material can be adjusted by changing conditions such as temperature conditions in the drying step after the coating step. The content of the solvent can be measured by a method using gas chromatography.

The total amount of the solvent contained in the photothermographic material of the present invention is preferably 5 to 1000 mg / m ² , preferably 10 to 300 mg / m ² . When the content is within the above range, a photothermographic material having a low fog density and a high sensitivity can be obtained.

  In the present invention, the exposure is preferably performed by laser scanning exposure. It is particularly preferable to use a laser scanning exposure machine in which the angle formed between the exposure surface of the photothermographic material and the scanning laser beam is not substantially perpendicular.

  Here, “substantially not perpendicular” means that the angle closest to the vertical during laser scanning is preferably 55 ° or more and 88 ° or less, more preferably 60 ° or more and 86 ° or less, and still more preferably. Means 70 degrees or more and 82 degrees or less.

  The beam spot diameter on the exposed surface of the photothermographic material when the laser beam is scanned onto the photothermographic material is preferably 200 μm or less, more preferably 100 μm or less. This is preferable in that the smaller the spot diameter, the smaller the angle of deviation of the laser incident angle from the vertical. The lower limit of the beam spot diameter is 10 μm. By performing such laser scanning exposure, it is possible to reduce image quality degradation related to reflected light such as generation of interference fringe-like unevenness.

  The exposure used in the present invention is preferably carried out using a laser scanning exposure machine that emits scanning laser light that is a vertical multi. Compared with a longitudinal single mode scanning laser beam, image quality degradation such as occurrence of interference fringe-like unevenness is reduced. In order to make a vertical multiplex, methods such as using return light or applying high-frequency superposition by multiplexing are preferable. The vertical multi means that the exposure wavelength is not single, and the distribution of the exposure wavelength is usually 5 nm or more, preferably 10 nm or more. The upper limit of the exposure wavelength distribution is not particularly limited, but is usually about 60 nm.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

Example 1
《Preparation of underdrawn support》
A commercially available biaxially stretched heat-fixed thickness of 175 μm, optical density of 0.170 (measured with Densitometer PDA-65 manufactured by Konica Corporation), 8 W / w on both sides of a PET film blue-colored with a blue dye having the following structure Apply a corona discharge treatment for m ² · min, coat the following undercoat coating solution a-1 to a dry film thickness of 0.8 μm and dry it to make the undercoat layer A-1, and vice versa The following undercoat coating solution b-1 was applied to the side surface so as to have a dry film thickness of 0.8 μm and dried to form an undercoat layer B-1.

<Undercoat coating liquid a-1>
Copolymer latex liquid of butyl acrylate (30% by mass) / t-butyl acrylate (20% by mass) / styrene (25% by mass) / 2-hydroxyethyl acrylate (25% by mass) (solid content 30%) 270 g
(C-1) 0.6g
Hexamethylene-1,6-bis (ethylene urea) 0.8g
Finish to 1L with water <Undercoating liquid b-1>
Copolymer latex solution of butyl acrylate (40% by mass) / styrene (20% by mass) / glycidyl acrylate (40% by mass) (solid content 30%)
270g
(C-1) 0.6g
Hexamethylene-1,6-bis (ethylene urea) 0.8g
Finish to 1L with water.

Subsequently, a corona discharge of 8 W / m ² · min is applied to the upper surfaces of the undercoat layer A-1 and the undercoat layer B-1, and the following undercoat upper layer coating solution a is applied on the undercoat layer A-1. -2 as an undercoat upper layer A-2 so that the dry film thickness is 0.1 μm, and the following undercoat upper layer coating solution b-2 is formed on the undercoat layer B-1 so that the dry film thickness is 0.4 μm Was coated as an undercoat upper layer B-2 having an antistatic function.

<Undercoating upper layer coating solution a-2>
Mass to become gelatin 0.4g / m ² (C-1) 0.2g
(C-2) 0.2g
(C-3) 0.1 g
Silica particles (average particle size 3μm) 0.1g
Finish to 1L with water <Undercoating upper layer coating solution b-2>
Sb-doped SnO ₂ (SNS10M; manufactured by Ishihara Sangyo Co., Ltd.) 60 g
80 g of latex liquid (solid content 20%) containing (C-4) as a component
Ammonium sulfate 0.5g
(C-5) 12g
Polyethylene glycol (mass average molecular weight 600) 6g
Finish to 1L with water.

<< Preparation of backcoat layer coating solution >>
While stirring 830 g of methyl ethyl ketone (MEK), 84.2 g of cellulose acetate butyrate (Eastman Chemical, CAB381-20) and 4.5 g of a polyester resin (Bostic, VitelPE2200B) were added and dissolved. Next, 0.30 g of infrared dye 1 was added to the dissolved liquid, and 4.5 g of F surfactant (Asahi Glass Co., Surflon KH40) dissolved in 43.2 g of methanol and F surfactant (large 2.3 g of Nippon Ink Co., Ltd. (MegaFag F120K) was added and stirred well until dissolved. Next, oleyl oleate was added at 2 and 5 g. Finally, 75 g of silica (WR Grace, Syloid 64X6000) dispersed in methyl ethyl ketone at a concentration of 1% by mass with a dissolver type homogenizer was added and stirred to prepare a backcoat layer coating solution.

<< Preparation of backcoat layer protective layer coating liquid >>
Cellulose acetate butyrate (10% methyl ethyl ketone solution) 15 g
Monodispersed 15% monodispersed silica (average particle size: 8 μm, surface treatment with 1% by mass of aluminum based on the total mass of silica) 0.030 g
C ₈ F ₁₇ (CH ₂ CH ₂ O) ₁₂ C ₈ F ₁₇ 0.05 g
C ₉ F ₁₇ —C ₆ H ₄ —SO ₃ Na 0.01 g
Stearic acid 0.1g
Oleyl oleate 0.1g
α-Alumina (Mohs hardness 9) 0.1g
The backcoat layer coating solution and the backcoat layer protective layer coating solution prepared in this way were extruded with a coater at an application rate of 50 m / min so that the dry film thickness was 3.5 μm. It apply | coated on undercoating upper layer B-2. The drying was performed for 5 minutes using a drying air having a drying temperature of 100 ° C. and a dew point temperature of 10 ° C.

<Polymer synthesis>
(Synthesis of polymer 1)
A 0.3 liter four-necked separable flask was equipped with a dropping device, a thermometer, a nitrogen gas introduction tube, a stirring device and a reflux condenser, charged with 20 g of methyl ethyl ketone and heated to 70 ° C. Next, the monomer was weighed, and a mixed solution obtained by adding Parroyl L2g manufactured by NOF Corporation to the monomer was dropped into the flask over 2 hours, and reacted at the same temperature for 5 hours. Thereafter, 80 g of methyl ethyl ketone was added and cooled to obtain a polymer solution of 50% by mass of the polymer. The% of monomer copolymer (molecular weight 50000) is as follows.

Bremer PME-400 20%
Blemmer PSE-400 20%
MAA 10%
DAAM 50%
Blemmer _{PME-400 :-( EO) m -CH} 3 (m ≒ methacrylate having 9) BLEMMER _{PSE-400 :-( EO) m -CH} 3 (m ≒ 9) methacrylate having an (EO; ethyleneoxy group )
The above are all made from Japanese fats and oils.

  MAA: methacrylic acid, DAAM: diaceseton acrylamide (Kyowa Hakko).

<< Preparation of photosensitive silver halide emulsion 1 >>
(Solution A1)
176.6g of polymer 1
Adjusted to pH = 6.0 with potassium hydroxide Compound A (* 1) (10% methanol aqueous solution) 10 ml
Potassium bromide 0.32g
Finished to 5429 ml with water (Solution B1)
0.67 mol / L silver nitrate aqueous solution 2635 ml
(Solution C1)
Potassium bromide 51.55g
Potassium iodide 1.47g
Finished to 660 ml with water (Solution D1)
Potassium bromide 154.9g
4.41 g of potassium iodide
K ₃ IrCl ₆ (equivalent to 4 × 10 ⁻⁵ mol / Ag) 50.0 ml
Finished to 1982 ml with water (Solution E1)
0.4 mol / L potassium bromide aqueous solution The following silver potential control amount (Solution F1)
Potassium hydroxide 0.71g
Finished to 20 ml with water (Solution G1)
56% acetic acid aqueous solution 18.0 ml
(Solution H1)
Anhydrous sodium carbonate 1.72 g
(* 1) Compound A: HO (CH ₂ CH ₂ O) _n (CH (CH ₃ ) CH ₂ O) ₁₇ (CH ₂ CH ₂ O) _m H (m + n = 5 to 7)
Using a mixing stirrer described in Japanese Patent Publication No. 58-58288, the solution A1 was adjusted to a ¼ amount of the solution B1 and a total amount of the solution C1 to 25 ° C. and pAg 8.09, while the mixture was mixed by the simultaneous mixing method. Addition took 45 minutes to nucleate. After 1 minute, the entire amount of solution F1 was added. During this time, the pAg was adjusted as appropriate using the solution E1. After the elapse of 6 minutes, 3/4 amount of the solution B1 and the whole amount of the solution D1 were added over 14 minutes and 15 seconds by the simultaneous mixing method while controlling to pAg8.09. After stirring for 5 minutes, the entire amount of Solution G1 was added to precipitate the silver halide emulsion. The supernatant was removed leaving 2000 ml of the sedimented portion, 10 L of water was added, and after stirring, the silver halide emulsion was sedimented again. The remaining portion of 1500 ml was left, the supernatant was removed, 10 L of water was further added, and after stirring, the silver halide emulsion was allowed to settle. After leaving 1500 ml of the sedimented portion and removing the supernatant, the solution H1 was added, the temperature was raised to 60 ° C., and the mixture was further stirred for 120 minutes. Finally, the pH was adjusted to 5.8, and water was added so that the amount was 1161 g per mole of silver, whereby photosensitive silver halide emulsion 1 was obtained.

  The silver halide grains in the silver halide emulsion 1 prepared as described above have a monodispersed cubic iodine odor with an average sphere equivalent diameter of 0.035 μm, a sphere equivalent diameter variation coefficient of 15%, and a [100] face ratio of 92%. It was silver halide grains. The average sphere equivalent diameter and the coefficient of variation of the sphere equivalent diameter were determined from the average of 1000 particles using an electron microscope. Further, the [100] face ratio of the particles was determined using the Kubelka-Munk method.

<< Preparation of non-photosensitive organic silver salt dispersion >>
<1> Aqueous solution of fatty acid alkali metal salt To 15208.8 ml of pure water, 652.5 ml of a 5 mol / L-KOH aqueous solution was added, the temperature was raised to 85 ° C., and 1162.4 g of behenic acid was dissolved when the temperature was stabilized. A potassium behenate solution was obtained.

<2> Aqueous solution containing silver ions An aqueous solution 3228.3 ml of 548.4 g of silver nitrate was prepared and kept at 10 ° C.

<3> First liquid in the reaction vessel 19000 ml of pure water was placed in the reaction vessel and kept at 30 ° C.

  The above <1> solution and <2> solution were added to the <3> solution under the conditions described in Table 1 below to produce non-photosensitive organic silver salt particles. The addition position of the potassium behenate solution and the addition position of the silver nitrate aqueous solution were symmetrically arranged around the stirring axis.

  The addition method described in Table 1 will be described with reference to FIG. In FIG. 1, the <1> solution is added into the additive solution 1 tank 11, the <2> solution is added into the additive solution 2 tank 12, and the <3> solution is measured into the reaction vessel 13. As a stirrer 14, the <1> liquid and the <2> liquid were added while stirring an auto homomixer MARK II model 20 manufactured by Tokushu Kika. The temperature of the reaction vessel 13 was controlled by supplying water at an appropriate temperature so that the temperature in Table 1 was reached. The pH in the reaction vessel was adjusted by controlling the flow rate of <1> solution.

  In Table 1, “simultaneous mixing” is a method of adding <1> liquid and <2> liquid to a reaction vessel containing <3> liquid while controlling them at the same time. “Successive addition” is <3> The addition of the <2> solution after adding the entire amount of the <1> solution to the reaction vessel containing the solution. The number of circulations is the number of circulations per unit time by stirring the reaction vessel.

  After completion of the addition of the fatty acid alkali metal salt solution or the silver ion-containing solution, the mixture was allowed to stand for 30 minutes at the same temperature. Thereafter, the solution was sent to a centrifuge, and deionized water was added, and washing with deionized water was continued until the conductivity of the drainage reached 30 μS / cm. After rinsing with water, centrifugal dehydration was carried out to remove excess water, followed by drying with a hot air circulating drier at 40 ° C. until there was no mass loss. 1-6 were obtained.

  Next, the dried non-photosensitive organic silver salt No. A preliminary dispersion was prepared using 1-6.

  26.26 g of polyvinyl butyral powder (Sekisui Chemical Co., Ltd., ESREC BL-5) was dissolved in 2000 g of methyl ethyl ketone and dried with a dissolver DISPERMAT CA-40M manufactured by VMA-GETZMANN. No. Each of 500 g of 1 to 6 was gradually added and mixed well to prepare preliminary dispersion No. 1-6 were prepared.

  Subsequently, the preliminary dispersion No. 1 to 6, media type disperser DISPERMAT SL filled with 80% of the internal volume of 0.5 mm zirconia beads (Torayserum manufactured by Toray) so that the residence time in the mill is 1.5 minutes using a pump. -C12EX type (manufactured by VMA-GETZMANN) and dispersed at a mill peripheral speed of 8 m / s. Organic silver salt dispersions 1 to 6 corresponding to 1 to 6 were obtained.

[Preparation of each additive]
(Preparation of stabilizer solution)
1.0 g of Stabilizer 1 and 0.31 g of potassium acetate were dissolved in 4.97 g of methanol to prepare a stabilizer solution.

(Preparation of infrared sensitizing dye solution)
19.2 mg of infrared sensitizing dye 1, 1.488 g 2-chloro-benzoic acid, 2.7779 g stabilizer 2 and 365 mg 5-methyl-2-mercaptobenzimidazole in 31.3 ml MEK in the dark And an infrared sensitizing dye solution was prepared.

(Preparation of additive solution a)
27.98 g of the reducing agent (A-8), 1.54 g of 4-methylphthalic acid, and 0.48 g of infrared dye 2 were dissolved in 110 g of MEK to obtain an additive solution a.

(Preparation of additive liquid b)
3.56 g of antifoggant 2 and 3.43 g of phthalazine were dissolved in 40.9 g of MEK to obtain additive solution b.

[Preparation of photosensitive layer coating solution]
Under an inert gas atmosphere (97% nitrogen), 50 g of the organic silver salt dispersion no. For each of 1 to 6, photosensitive layer coating solutions were prepared by the following method. 10 g of the photosensitive silver halide emulsion 1 and 5.11 g of methyl ethyl ketone were kept at 21 ° C. with stirring, 390 μl of antifoggant-1 (10% methanol solution) was added, and the mixture was stirred for 1 hour. Further, 494 μl of calcium bromide (10% methanol solution) was added and stirred for 20 minutes. Subsequently, 167 μl of a stabilizer solution was added and stirred for 10 minutes, and then 1.32 g of the infrared sensitizing dye solution was added and stirred for 1 hour. Thereafter, the temperature was lowered to 13 ° C. and further stirred for 30 minutes. While maintaining the temperature at 13 ° C., 13.31 g of polyvinyl butyral (Butvar B-79) was added as a binder resin and stirred for 30 minutes, and then 1.084 g of tetrachlorophthalic acid (9.4 mass% methyl ethyl ketone solution) was added. And stirred for 15 minutes. While further stirring, 12.43 g of additive liquid a, 1.6 ml of Desmodur N3300 (Mobey aliphatic isocyanate 0% methyl ethyl ketone solution) and 4.27 g of additive liquid b were sequentially added and stirred. Photosensitive layer coating solution No. 1-6 were obtained.

[Preparation of matting agent dispersion]
Cellulose acetate butyrate (Eastman Chemical, 7.5 g CAB171-15) is dissolved in 42.5 g of MEK, and 5 g of calcium carbonate (Speciality Minerals, Super-Pflex200) is added to the cellulose acetate butter with a dissolver type homogenizer. A matting agent dispersion was prepared by dispersing at 8000 rpm for 30 minutes.

[Preparation of surface protective layer coating solution]
While stirring MEK865g, cellulose acetate butyrate (Eastman Chemica, CAB171-15) 96g, polymethylmethacrylic acid (Rohm & Haas, Paraloid A-21) 4.5g, vinyl sulfone compound (HD-1) 1. 5 g, 1.0 g of benzotriazole, and 1.0 g of F-based surfactant (Asahi Glass Co., Surflon KH40) were added and dissolved. Next, 30 g of the above matting agent dispersion was added and stirred to prepare a surface protective layer coating solution.

[Preparation of photothermographic material]
(Photosensitive layer side coating)
The photosensitive layer coating solution No. 1 to 6 and the surface protective layer coating solution were simultaneously coated on the undercoat upper layer A-2 of the support using a known extrusion coater. The coating was carried out so that the photosensitive layer had a coated silver amount of 1.7 g / m ² and the surface protective layer had a dry film thickness of 2.5 μm. Thereafter, drying was performed for 10 minutes using a drying air having a drying temperature of 75 ° C. and a dew point temperature of 10 ° C. to prepare photosensitive materials A to F.

[Photo performance]
(Exposure, development)
From the photosensitive layer side of the photosensitive material produced as described above, exposure by laser scanning was given by an exposure machine using a semiconductor laser converted into a longitudinal multimode with a wavelength of 800 nm to 820 nm by high frequency superposition as a light source. At this time, an image was formed by setting the angle of the exposure surface of the photothermographic material and the exposure laser beam to 75 degrees. (Note that an image with less unevenness and unexpectedly good sharpness or the like was obtained compared to the case where the angle was 90 degrees.)
Thereafter, using an automatic developing machine having a heat drum, the surface protective layer of the photothermographic material and the drum surface were brought into contact with each other, and heat development was performed at 123 ° C. for 12.5 seconds. At that time, exposure and development were performed in a room conditioned at 23 ° C. and 50% RH.

(Fog, storage stability)
The obtained image was measured with a densitometer, and the fog density (unexposed area density, Dmin) was measured. With respect to storability, the photosensitive material was stored in a constant temperature device at 40 ° C. for 3 days, and the fluctuation value of the fog density before and after the storage in the constant temperature device was measured. The results are shown in Table 2.

  As is apparent from Table 2, it can be seen from the photographic performance that the photosensitive material using the non-photosensitive organic silver salt of the present invention is very excellent.

Example 2
Density unevenness evaluation was performed on the photosensitive materials A to F of Example 1.

The density unevenness of the photosensitive material on the Schaukasten was performed according to the following evaluation criteria. The results are shown in Table 3.
○: Density unevenness △: Density unevenness but no problem in diagnosis ×: Density unevenness causes a problem in diagnosis

  As is apparent from Table 3, it can be seen that the photosensitive material using the non-photosensitive organic silver salt of the present invention has no density unevenness and excellent coating properties.

It is a schematic diagram of the reaction container which can be used by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Additive liquid 1 tank 12 Additive liquid 2 tank 13 Reaction container 14 Mixing stirrer 15 Additive liquid 1 flow meter 16 Additive liquid 2 flow meter 17 Additive liquid 1 pump 18 Additive liquid 2 pump 19 Sensor for pH measurement 20 pAg measurement sensor

Claims (7)

When producing the non-photosensitive organic silver salt, as part 1, in the reaction vessel, 1 part of water, an organic solvent, or a mixture of water and an organic solvent, and an aqueous solution containing silver ions to be added are added. And the liquid in reaction container is stirred and pAg of liquid is set to 2.5-3.8. Next, as process 2, the temperature in this reaction container is controlled to 20-40 degreeC, and silver ion is made Production of a non-photosensitive organic silver salt characterized in that an aqueous solution containing and an aqueous solution of a fatty acid alkali metal salt are simultaneously added and stirred, and the pH is controlled to 4 to 8 to produce a non-photosensitive organic silver salt Method. 2. The method for producing a non-photosensitive organic silver salt according to claim 1, wherein the pAg in Step 1 in producing the non-photosensitive organic silver salt is 2.8 to 3.1. The method for producing a non-photosensitive organic silver salt according to claim 1 or 2, wherein the temperature in the reaction vessel in Step 2 when producing the non-photosensitive organic silver salt is 20 to 30 ° C. The non-photosensitive organic silver according to any one of claims 1 to 3, wherein the pH in the reaction vessel in step 2 in producing the non-photosensitive organic silver salt is controlled to 4-6. Method for producing salt. The method for producing a non-photosensitive organic silver salt according to any one of claims 1 to 4, wherein the stirring Reynolds number of the reaction solution in the reaction vessel is 125,000 or more and 350,000 or less. The number of circulations per unit time by stirring of the reaction solution in the reaction vessel is 4.3 times / minute or more and 12.0 times / minute or less, 5. Of producing a non-photosensitive organic silver salt. A photosensitive layer containing a non-photosensitive organic silver salt produced by the production method according to any one of claims 1 to 6, a photosensitive silver halide grain, a reducing agent and a binder on a support. A photothermographic material characterized by the above.

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