JP2000010229A - Heat developing recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat developing recording material good in silver color tone and capable of giving images having a high S/N. SOLUTION: In a heat developing photosensitive material provided with at least an organic silver salt, a reducing agent and a binder on a support, a polymer latex containing <=600 ppm ammonium ion, sodium ion and potassium ion in the total content is used in an amount of >=50 wt.% the total binder of a layer containing the organic silver salt for this heat developing recording material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-developable recording material having a high S / N ratio, a good color tone, and good characteristics for stably reproducing image information. More specifically, the present invention relates to a photosensitive recording material for a laser image setter or a laser imager (hereinafter, referred to as an LI photosensitive material). The present invention relates to a heat-developable recording material having good characteristics that can be reproduced stably.

[0002]

2. Description of the Related Art There are many known photosensitive materials having a photosensitive layer on a support and forming an image by exposing the image. Among them, a technique of forming an image by thermal development is widely known as a system that can simplify environmental preservation and image forming means.

[0003] In recent years, there has been a strong demand in the medical field to reduce the amount of processing waste liquid from the viewpoint of environmental conservation and space saving. Therefore, a photosensitive heat-developable material for medical diagnostics and photography that can be efficiently exposed by a laser imagesetter or laser imager and can form a sharp black image with high resolution and sharpness The demand for is increasing. These photosensitive heat-developable materials can eliminate the use of solution-based processing chemicals, and can provide customers with a simpler heat-development processing system that does not damage the environment.

On the other hand, semiconductor laser technology, which has made rapid progress in recent years, has made it possible to reduce the size of medical image output devices. Naturally, the technology of infrared-sensitive heat-developable silver halide photographic materials that can use a semiconductor laser as a light source was also developed.
No. 87, JP-A-5-341432, JP-A-6-194781, JP-A-6-1994
No. 301141 is disclosed, and as antihalation techniques, JP-A-7-13295 and US Pat. No. 5,380,635 are disclosed. In the case of a photosensitive material premised on infrared exposure, the visible absorption of a sensitizing dye or an antihalation dye can be significantly reduced, and a photosensitive material having substantially no color can be easily produced.

Methods for forming an image by thermal development include, for example, US Pat. Nos. 3,152,904 and 3,457,075.
And D. Morgan and B.A. Shely
"Thermal Processed Silver System (Thermally
Processed Silver Systems ”(Imaging Processesan and Materials)
d Materials) Neblette 8th edition, Sturge,
V. Walworth, A .; Shep
p) Compilation, page 2, 1969). Such photosensitive materials are prepared by dispersing a non-photosensitive reducible silver source (eg, an organic silver salt), a catalytically active amount of a photocatalyst (eg, silver halide), and a silver reducing agent, usually in an organic binder matrix. It is contained in. The photosensitive material is stable at normal temperature, but when heated to a high temperature (for example, 80 ° C. or higher) after exposure, silver is reduced through a redox reaction between a reducible silver source (which functions as an oxidizing agent) and a reducing agent. Generate This oxidation-reduction reaction is promoted by the catalytic action of the latent image generated by the exposure. The silver formed by the reaction of the reducible silver salt in the exposed areas provides a black image, which contrasts with the unexposed areas, resulting in the formation of an image.

Conventionally, photothermographic materials of this type have been known, but most of these photosensitive materials form a photosensitive layer by applying a coating solution containing an organic solvent such as toluene, methyl ethyl ketone or methanol as a solvent. Has formed.
The use of an organic solvent as a solvent is disadvantageous not only in adverse effects on the human body in the manufacturing process but also in cost due to recovery of the solvent and the like.

Therefore, a method of forming a photosensitive layer (hereinafter also referred to as "aqueous photosensitive layer") using a coating solution of a water solvent which does not have such a concern has been considered. For example, JP-A-49-52626 and JP-A-53-116144 disclose examples using gelatin as a binder.
JP-A-50-151138 discloses an example in which polyvinyl alcohol is used as a binder.

Further, JP-A-60-61747 discloses an example in which gelatin and polyvinyl alcohol are used in combination. As another example, JP-A-58-28737 describes an example of a photosensitive layer using water-soluble polyvinyl acetal as a binder.

[0009] However, in these examples, the fog was high and the color tone of the formed image was very poor and did not reach the level of practical use. On the other hand, Japanese Patent Application Laid-Open Nos. 10-10669 and 10-62899 A technique for forming a photosensitive layer using an aqueous solvent using latex as a binder has been disclosed. This technique has opened the way to the production of heat-developable recording materials that have good fog and image tone and are preferable from the viewpoints of environmental protection, safety, cost, and the like. However, with the progress of the times, deficiencies in photographic performance have become conspicuous even with these technologies, and there has been a technology for providing a heat-developable recording material having good characteristics with a practically sufficient S / N and color tone. Was desired.

[0010]

Accordingly, an object of the present invention is to provide an organic silver salt-containing layer by applying a coating solution of a water solvent which is advantageous in terms of environmental protection and cost. A heat-developable recording material having good characteristics with high S / N and good color tone, and thus capable of stably reproducing image information;
In particular, it is to provide a photothermographic material.

[0011]

The above object has been achieved by the present invention described below. (1) In a photothermographic material having at least an organic silver salt, a reducing agent, and a binder on a support, ammonium ion, sodium ion, and potassium ion are contained in an amount of 50% by weight or more of the total binder in the organic silver salt-containing layer. A heat-developable recording material characterized by using a polymer latex containing 600 ppm or less in total. (2) The heat-developable recording material according to (1), wherein the total of sodium ions and potassium ions contained in the polymer latex is 200 ppm or less. (3) The heat-developable recording material according to (2) above, wherein the polymer latex contains 200 ppm or less of ammonium ions. (4) The above (1) to (3) containing a photosensitive silver salt
Any one of the heat-developable recording materials. (5) 25% 60% of the polymer of the polymer latex
The heat-developable recording material according to any one of (1) to (4), wherein the equilibrium water content at RH is 2% by weight or less. (6) The heat-developable recording material according to any one of the above (1) to (5), wherein the organic silver salt is an organic carboxylic acid silver salt.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The photothermographic material of the present invention is preferably a photothermographic material containing an organic silver salt, a reducing agent and a binder, and further containing a photosensitive silver salt. A polymer latex that enables water-based coating that is advantageous in terms of environment and cost is used as 50% by weight or more of the binder in the organic silver salt-containing layer. Such a polymer latex is regulated so that the total amount of ammonium ions, sodium ions and potassium ions is 600 ppm or less as a cation content when added to the coating solution for the organic silver salt-containing layer (that is, the image forming layer). It is something. As a result, a heat-developable recording material having a good silver tone and providing a high S / N image can be obtained. On the other hand, when the total amount of the above cations exceeds 600 ppm, the silver tone deteriorates and S
/ N is significantly reduced. It is considered that the silver tone mainly depends on the sum of sodium ions and potassium ions, and the S / N depends on the sum of the above three ions.

First, the polymer latex of the present invention will be described. There is no particular limitation on the polymer latex, acrylic resin, polyester resin, rubber-based resin (for example, SBR resin), polyurethane resin, vinyl chloride resin, vinyl acetate resin, vinylidene chloride resin, polyolefin resin, and hydrophobic polymers such as these or the like A latex of a copolymer can be used. For polymer latex, see “Synthetic Resin Emulsion (Edited by Okudadaira and Hiroshi Inagaki,
Published by The Society of Polymer Publishing (1978)), "Application of Synthetic Latex (Takaaki Sugimura, Yasuo Kataoka, Soichi Suzuki, Keiji Kasahara, edited by Keiji Koshihara (1993))", "Chemistry of Synthetic Latex (Souichi Muroi) Author, published by the Society of Polymer Publishing (1970)).

The polymer may be a linear polymer, a branched polymer or a crosslinked polymer. The polymer may be a so-called homopolymer in which a single monomer is polymerized, or a copolymer in which two or more monomers are polymerized. In the case of a copolymer, it may be a random copolymer or a block copolymer. The polymer has a number average molecular weight of 5000 to 100000, preferably 10,000 to 200,000. If the molecular weight is too small, the mechanical strength of the emulsion layer is insufficient, and if it is too large, the film-forming properties are poor, which is not preferable.

The average particle size of the polymer latex particles is 1 to 5
The range of 0000 nm is preferable, and the range of about 5 to 1000 nm is more preferable. The sphere diameter distribution of the polymer latex is not particularly limited, and may be a substance having a wide particle size distribution or a substance having a monodisperse sphere diameter distribution.

As the polymer latex of the present invention, other than a polymer latex having a normal uniform structure, a so-called core / polymer latex is used.
Shell type latex may be used. In this case, it may be preferable to change the glass transition temperature of the core and the shell.

The minimum film forming temperature (MFT) of the polymer latex of the present invention is from -30 ° C to 90 ° C, more preferably 0 ° C.
The temperature is preferably about 70C. A film forming aid may be used to control the minimum film forming temperature. The film-forming aid is also called a plasticizer, and is an organic compound (usually an organic solvent) that lowers the minimum film-forming temperature of the polymer latex. For example, the above-mentioned “Synthetic latex chemistry (Souichi Muroi, published by Polymer Publishing Association ( 1970))).

As the polymer latex of the present invention, 25
Preferably, the polymer has an equilibrium water content of 2% by weight or less at 60 ° C. and 60% RH, more preferably 0.1% by weight or more and 1.5% by weight or less, further preferably 0.02% by weight or more and 1% by weight or less. It is.

The term "equilibrium water content at 25 ° C and 60% RH" used in the present invention refers to the weight W _{1 of} a polymer which is in a moisture-conditioning equilibrium in an atmosphere of 25 ° C and 60% RH, and a polymer which is absolutely dried at 25 ° C. Can be expressed as follows using the weight W ₀ of

Equilibrium water content at 25 ° C. and 60% RH = ｛(W ₁ −
W ₀ ) / W ₀ ｝ × 100 (% by weight) For the definition and measurement method of water content, refer to “Polymer Engineering Course 14, Polymer Materials Testing Method (Polymer Society, Jinjinshokan)”, for example. can do.

There is no particular limitation on the method for obtaining the polymer latex of the present invention. And a method of purifying a latex that has been synthesized once using a separation functional polymer described below.

The separation functional polymer generally includes an ion exchange resin and a separation functional membrane. As the ion exchange resin preferably used in the present invention, a strongly basic or weakly basic anion exchange resin, a strong acidic or A weakly acidic cation exchange resin, a porous ion exchange resin having a giant stitch structure, or a chelate resin can be preferably used. As the separation function membrane, a reverse osmosis membrane (cellulose acetate, cellulose triacetate, polypiperazine amide, wholly aromatic polyamide, polybenzimidazolone, crosslinked polyether, alkyl allyl polyamide-polyurea, polyacrylonitrile) , Sulfone polysulfone type, etc.), microfiltration membrane (cellulose acetate type, polypropylene type, polyvinyl chloride type, polyvinyl alcohol type, polyester type, polyamide type, polyimide type etc.), ultrafiltration membrane (cellulose type, cellulose / regenerated cellulose) System, polyimide system, polysulfone system,
Polyamide-based, polyvinyl chloride-based, polypropylene-based,
Polyvinylidene chloride and the like. It may be a flat membrane type, a tubular type, a hollow fiber type, a spiral type, or a pleated type. ), Dialysis membrane (cellulose-based, acrylonitrile-based hollow fiber membrane, ethylene / vinyl alcohol copolymer-based hollow fiber membrane, polymethyl methacrylate-based hollow fiber membrane, polysulfone-based hollow fiber membrane, polypropylene-based hollow fiber membrane, regenerated cellulose-based membrane, etc.) Ion exchange membranes used in electrodialysis (inorganic ion exchange membranes, styrene / divinylbenzene crosslinked polymer sulfonated membranes, chloromethylstyrene / divinylbenzene crosslinked polymer aminated membranes, vinylpyridine / divinylbenzene crosslinked polymer N-
Methylated film, perfluorocarbon carboxylic acid film,
A styrene / butadiene-based film or the like) is preferably used. In the present invention, more preferably, a separation function membrane can be used. More preferably, an ultrafiltration membrane or a dialysis membrane can be used. The molecular weight cut off of ultrafiltration or dialysis membrane preferably used in the present invention is not particularly limited as long as the effects of the present invention are exhibited, but is usually about 5,000 to 100,000, preferably about 15,000 to 60,000. . The ultrafiltration treatment is usually performed plural times.

These materials are described in detail in Chapters 16 and 17 of "Functional Polymer Materials, Products and Markets, 1994 Edition" (published by Tokyo Techno Brain). For example, Rohm & Haas (Amberlite, Duolite), Dow Chemical (Dowex), etc. as ion exchange resins, Asahi Kasei Kogyo (Aciplex), Asahi Glass (Seremion), Tokuyama Delivery (Neoceptor) as ion exchange membranes , Dupont (Nafion), Fuji Photo Film Co., Ltd. (microfilter)
As an ultrafiltration membrane, Asahi Kasei Kogyo (Microza U
F-Module, Kuraray (MU), Daicel Chemical (Molsep), etc.
0), Nitto Denko (NTR7250), Dupont (B9, B10), etc., as the dialysis membrane, Sanko Junyaku (dialysis membrane, cellulose tube; VI
SKASE).

In the present invention, a preferable silver color tone and S / N are simultaneously expressed by making the total of ammonium ion, sodium ion, and potassium ion of the polymer latex finally added at the time of preparing the coating solution 600 ppm or less (0 ppm or more). The effect to be obtained is obtained.

Regarding the content of each cation, the smaller the total amount of sodium ions and potassium ions, the better the effect can be obtained.
Is more preferable.

Furthermore, the ammonium ion is 200 pp
Particularly preferable effects can be obtained when the total amount of sodium ions and potassium ions is 200 ppm or less (0 ppm or more).

In the present invention, as described above, it is particularly important to reduce the total amount of sodium ions and potassium ions.

The cation concentration is usually measured by ion chromatography. Although the experimental method is described in detail in the textbook, specific examples are shown in Examples.

The treatment with the polymer having a separating function lowers the ionic conductivity. Preferred ionic conductivity of the polymer latex after treatment with a separation function polymer,
0.05 mS / cm or more and 3.0 mS / cm or less, more preferably 0.1 mS / cm
2.5 mS / cm or less, more preferably 0.15 mS / cm or more 2.0
mS / cm or less. In this case, since the ionic conductivity depends on the polymer concentration of the polymer latex, in the present invention, the value is set at a polymer concentration of 40% by weight. That is, upon measurement, the polymer concentration is adjusted to 40 wt% by diluting or concentrating with distilled water, and the measurement is performed at 25 ° C.

Specific examples of preferred polymers include the following. In the following, the raw material monomers are used, the numerical value in parentheses is wt%, and the molecular weight is the number average molecular weight.

Latex of P-1; -MMA (70) -EA (27) -MAA (3)-(molecular weight 37000) P-2; -MMA (70) -2EHA (20) -St (5) -AA (5) -Latex (molecular weight 40000) P-3; -St (50) -Bu (47) -MAA (3) -latex (molecular weight 4500
0) P-4; -St (68) -Bu (29) -AA (3)-latex (MW 60000) P-5; -St (70) -Bu (27) -IA (3)-latex (Molecular weight 12000
0) Latex of P-6; -St (75) -Bu (24) -AA (1)-(molecular weight 10800
0) P-7; -St (60) -Bu (35) -DVB (3) -MAA (2)-latex (molecular weight 150,000) P-8; -St (70) -Bu (25) -DVB ( 2) -AA (3)-latex (molecular weight 280000) P-9; -VC (50) -MMA (20) -EA (20) -AN (5) -AA (5)-latex (molecular weight 80000) P-10; -VDC (85) -MMA (5) -EA (5) -MAA (5)-latex (molecular weight 67,000) P-11; -Et (90) -MAA (10)-latex (molecular weight) 12000) P-12; -St (70) -2EHA (27) -AA (3) latex (molecular weight 1300
00) P-13; -MMA (63) -EA (35) -AA (2) latex (molecular weight 3300
0)

Abbreviations of the above structures represent the following monomers.
MMA; methyl methacrylate, EA; ethyl acrylate, MAA; methacrylic acid, 2EHA; 2-ethylhexyl acrylate, St; styrene, Bu; butadiene, AA; acrylic acid, DVB; divinylbenzene, VC; vinyl chloride, AN;
Acrylonitrile, VDC; vinylidene chloride, Et; ethylene, IA; itaconic acid.

The polymers described above are commercially available, and the following polymers can be used. Examples of acrylic resin include Sebian A-4635, 46683, 4601 (all manufactured by Daicel Chemical Industries, Ltd.), Nipol Lx811, 814, 821, 820, 85
Examples of polyester resins such as 7 (all manufactured by Zeon Corporation) include FINETEX ES650, 611, 675, 850 (all manufactured by Dainippon Ink and Chemicals), WD-size, WMS (all manufactured by Eastman Chemical Co., Ltd.) HYDRA is an example of a polyurethane resin.
Examples of rubber resins such as NAP10, 20, 30, 40 (all manufactured by Dainippon Ink and Chemicals, Inc.) include LACSTAR 7310K, 3307B,
4700H, 7132C (all manufactured by Dainippon Ink and Chemicals, Inc.), Nipol Lx
Examples of vinyl chloride resins such as 416, 410, 438C, and 2507 (all manufactured by Nippon Zeon Co., Ltd.)
Examples of vinylidene chloride resin, such as L502,
Examples of olefin resins such as L513 (manufactured by Asahi Chemical Industry Co., Ltd.) include Chemipearl S120 and SA100 (Mitsui Petrochemical
And the like).

These polymers may be used alone as a polymer latex, or may be blended as required.

The polymer latex used in the present invention is particularly preferably a styrene-butadiene copolymer latex. The weight ratio of the styrene monomer unit to the butadiene monomer unit in the styrene-butadiene copolymer is preferably from 40:60 to 95: 5. Other copolymer components such as acrylic acid and methacrylic acid may be contained, and the proportion of the copolymer of the monomer unit of styrene and the monomer unit of butadiene is preferably 60 to 99% by weight. The preferred molecular weight range is the same as described above.

Styrene preferably used in the present invention
As the butadiene copolymer latex, the above-mentioned P-3
~ P-8, commercial products LACSTAR-3307B, 7132C, Nipol Lx4
16, and the like.

The organic silver salt-containing layer of the present invention comprises
Use polymer latex as 50% by weight or more.
It is more preferable to use the above-mentioned polymer latex as the amount by weight or more.

If necessary, a hydrophilic polymer such as gelatin, polyvinyl alcohol, methylcellulose, hydroxypropylcellulose, carboxymethylcellulose, or hydroxypropylmethylcellulose may be added to the organic silver salt-containing layer in an amount of 50% by weight or less of the whole binder. Is also good. The addition amount of these hydrophilic polymers is 30% by weight or less of the total binder of the organic silver salt-containing layer, more preferably 20% by weight.
The following is preferred.

The organic silver salt-containing layer of the present invention comprises 30% by weight of a solvent.
It is preferable to form the coating liquid which is water as described above by drying after coating.

The polymer latex of the present invention needs to be soluble or dispersible in an aqueous solvent (aqueous solvent). The aqueous solvent in which the polymer is soluble or dispersible is water or a mixture of water and 70% by weight or less of a water-miscible organic solvent. Examples of the water-miscible organic solvent include, for example, alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol, methyl cellosolve,
Examples include cellosolves such as ethyl cellosolve and butyl cellosolve, and methyl acetate and dimethylformamide.

The term "aqueous solvent" is used herein even in the case where the polymer is not thermodynamically dissolved but exists in a so-called dispersed state.

The water content of the solvent of the coating solution is 50 wt% or more,
It is more preferably at least 70 wt%. To give an example of a specific solvent composition, in addition to water, water / methyl alcohol = 90/1
0, water / methyl alcohol = 70/30, water / ethyl alcohol = 90/10, water / isopropanol = 90/10, water / methyl alcohol / dimethylformamide = 80/15/5, water / methyl alcohol / ethyl cellosolve = 85/10/5, water / methyl alcohol / isopropyl alcohol = 85/10/5 (however, the figures are wt%).

The organic silver salt-containing layer, which is the image forming layer of the present invention, is formed using a polymer latex.
The weight ratio of the organic silver salt is preferably 1/1 to 10/1, and more preferably 1/5 to 4/1. The total binder amount of the organic silver salt-containing layer is 0.
The range is ^{2 to} 30 g / m ² , more preferably 1 to 15 g / m ² .

The organic silver salt-containing layer is usually a photosensitive layer (emulsion layer) containing a photosensitive silver halide, which is preferably a photosensitive silver salt. The weight ratio of total binder / silver halide is preferably in the range of 400 to 5, more preferably 200 to 100.

The organic silver salt that can be used in the present invention is
Relatively stable to light, but forms a silver image when heated to 80 ° C. or higher in the presence of an exposed photocatalyst (such as a latent image of photosensitive silver halide) and a reducing agent It is a silver salt. The organic silver salt can be any organic substance including a source capable of reducing silver ions. Silver salts of organic acids, in particular silver salts of long-chain fatty carboxylic acids (with 10 to 30, preferably 15 to 28 carbon atoms) are preferred. Complexes of organic or inorganic silver salts wherein the ligand has a complex stability constant in the range of 4.0 to 10.0 are also preferred. The silver donor is preferably about 5 to 70 watts of the imaging layer.
t% can be composed. Preferred organic silver salts include silver salts of organic compounds having a carboxyl group. Examples of these include, but are not limited to, silver salts of aliphatic carboxylic acids and silver salts of aromatic carboxylic acids. Preferred examples of the silver salt of the aliphatic carboxylic acid include silver behenate, silver arachidate, silver stearate, silver oleate, silver laurate, silver caproate, silver myristate, silver palmitate, silver maleate, and fumarate. Silver, silver tartrate, silver linoleate, silver butyrate and silver camphorate, and mixtures thereof.

The organic acid silver which is preferably used in the present invention is
It is prepared by reacting silver nitrate with an alkali metal salt (eg, Na salt, K salt, Li salt, etc.) solution or suspension of the organic acid described above. The alkali metal salt of an organic acid of the present invention is obtained by treating the above organic acid with an alkali. The silver salt of an organic acid of the present invention can be carried out batchwise or continuously in any suitable vessel. The stirring in the reaction vessel can be performed by any stirring method depending on the required characteristics of the particles. The silver salt of an organic acid can be prepared by gradually or rapidly adding an aqueous solution of silver nitrate to a reaction vessel containing a solution or suspension of an alkali metal salt of an organic acid, or by preparing an organic acid prepared in advance in a reaction vessel containing an aqueous solution of silver nitrate. Preferably, a method of gradually or rapidly adding an alkali metal salt solution or suspension, and a method of simultaneously adding a previously prepared aqueous solution of silver nitrate and a solution or suspension of an organic acid alkali metal salt into a reaction vessel are preferably used. Can be.

The silver nitrate aqueous solution and the organic acid alkali metal salt solution or suspension may be of any concentration for controlling the particle size of the prepared organic acid silver, and may be added at any addition rate. it can. The silver nitrate aqueous solution and the organic acid alkali metal salt solution or suspension can be added by a method of adding at a constant addition rate, an accelerated addition method by an arbitrary time function, or a deceleration addition method. Also, the reaction solution may be added to the liquid surface,
Further, it may be added to the liquid. In the case of a method in which a previously prepared aqueous silver nitrate solution and an organic acid alkali metal salt solution or suspension are simultaneously added to the reaction vessel, either the silver nitrate aqueous solution or the organic acid alkali metal salt solution or suspension is preceded. Although it can be added, it is preferable to add the silver nitrate aqueous solution in advance. The degree of precedence is preferably 0 to 50 vol%, particularly preferably 0 to 25 vol% of the total amount. Further, as described in JP-A-9-127643, a method of adding while controlling the pH or silver potential of the reaction solution during the reaction can be preferably used.

The silver nitrate aqueous solution or organic acid alkali metal salt solution or suspension to be added depends on the required characteristics of the particles.
pH can be adjusted. Any acid or alkali can be added for pH adjustment. Depending on the required characteristics of the particles, for example, the temperature in the reaction vessel can be set arbitrarily for controlling the particle size of the prepared organic acid silver salt. Alternatively, the suspension can also be adjusted to any temperature. The organic acid alkali metal salt solution or suspension is preferably heated and kept at 50 ° C. or higher in order to ensure fluidity of the solution.

The organic silver salt used in the present invention is preferably prepared in the presence of a tertiary alcohol. The tertiary alcohol used in the present invention preferably has a total carbon number of 15 or less, particularly preferably 10 or less. Preferred examples of the tertiary alcohol include tert-butanol, but the present invention is not limited thereto.

The tertiary alcohol used in the present invention may be added at any time during the preparation of the silver salt of an organic acid, but may be added during the preparation of the alkali metal salt of an organic acid to dissolve the alkali metal salt of the organic acid. Is preferred. The amount of the tertiary alcohol of the present invention can be arbitrarily used in a weight ratio of 0.01 to 10 with respect to H ₂ O as a solvent at the time of preparing the organic acid silver, but is preferably in a range of 0.03 to 1. Is preferred.

Silver salts of compounds containing a mercapto group or a thione group and derivatives thereof can also be used.
Preferred examples of these compounds include 3-mercapto-4
-Phenyl-1,2,4-triazole silver salt, 2-mercaptobenzimidazole silver salt, 2-mercapto-5-aminothiadiazole silver salt, 2- (ethylglycolamide) benzothiazole silver salt, S- Silver salts of thioglycolic acid such as silver salts of alkylthioglycolic acid (where the alkyl group has 12 to 22 carbon atoms), silver salts of dithiocarboxylic acids such as silver salts of dithioacetic acid, silver salts of thioamides, 5 -Carboxyl-1-methyl-2-phenyl-4-thiopyridine silver salt, mercaptotriazine silver salt, 2-mercaptobenzoxazole silver salt, silver salts described in U.S. Pat.No.4,123,274, for example, 3-amino-5 Silver salts of 1,2,4-mercaptothiazole derivatives such as -benzylthio-1,2,4-thiazole silver salt, 3- (3-carboxyethyl) -4- described in U.S. Pat.No. 3,301,678
Includes silver salts of thione compounds such as silver salt of methyl-4-thiazoline-2-thione. Furthermore, compounds containing an imino group can also be used. Preferred examples of these compounds include silver salts of benzotriazole and derivatives thereof,
For example, silver salts of benzotriazole such as silver methylbenzotriazole, silver salts of halogen-substituted benzotriazole such as silver 5-chlorobenzotriazole, U.S. Pat.
0,709 1,2,4-triazole or 1-H-
Includes silver salts of tetrazole, silver salts of imidazole and imidazole derivatives, and the like. For example, U.S. Pat.
Various silver acetylide compounds as described in No. 1 and 4,775,613 can also be used.

The shape of the organic silver salt that can be used in the present invention is not particularly limited, but a needle crystal having a short axis and a long axis is preferable. In the present invention, the minor axis is 0.01 μm or more and 0.2 μm or more.
0 μm or less, major axis of 0.10 μm or more and 5.0 μm or less, minor axis of 0.01 μm or more and 0.15 μm or less, and major axis of 0.10 μm or more and 4.0 μm or less are more preferred. The particle size distribution of the organic silver salt is preferably monodispersed. Monodisperse and the minor axis, the percentage of the value obtained by dividing the standard deviation of the length of each major axis by each minor axis, major axis is preferably 100% or less, more preferably 80% or less,
More preferably, it is 50% or less. The shape of the organic silver salt can be measured from a transmission electron microscope image of the organic silver salt dispersion. As another method of measuring the monodispersity, there is a method of determining the standard deviation of the volume-weighted average diameter of the organic silver salt, the percentage of the value divided by the volume-weighted average diameter (coefficient of variation) is preferably 100% or less, more It is preferably at most 80%, more preferably at most 50%. As a measuring method, for example, the particle size (volume weighted average diameter) obtained by irradiating a laser beam to an organic silver salt dispersed in a liquid and obtaining an autocorrelation function with respect to a time change of fluctuation of the scattered light is obtained. Can be.

The organic silver salt which can be used in the present invention is
Preferably, desalting can be performed. The method for desalting is not particularly limited, and a known method can be used. However, a known filtration method such as centrifugal filtration, suction filtration, ultrafiltration, or floc-forming water washing by a coagulation method can be preferably used.

In the present invention, in order to obtain an organic silver salt solid dispersion having a high S / N, a small particle size and no aggregation, an organic silver salt which is an image forming medium and a photosensitive silver salt are substantially contained. It is preferable to use a dispersion method in which a water dispersion liquid which is not included in the liquid is converted into a high-speed stream and then the pressure is reduced.

After passing through such steps, the mixture is mixed with an aqueous solution of a photosensitive silver salt to prepare a coating solution for a photosensitive image forming medium. When a heat-developable recording material is prepared using such a coating solution, a haze is low, and a low-fogging and high-sensitivity heat-developable recording material can be obtained. On the other hand, when the photosensitive silver salt is coexistent when the light is converted into a high-pressure and high-speed flow and dispersed, the fog increases and the sensitivity is liable to decrease remarkably. When an organic solvent is used instead of water as a dispersion medium, haze increases, fog increases, and sensitivity tends to decrease. on the other hand,
When a conversion method for converting a part of the organic silver salt in the dispersion liquid into the photosensitive silver salt is used instead of the method of mixing the aqueous solution of the photosensitive silver salt, the sensitivity tends to be lowered.

In the above, the aqueous dispersion converted and dispersed under high pressure and high speed does not substantially contain a photosensitive silver salt, and its content is relative to that of a non-photosensitive organic silver salt. 0.
The content is 1 mol% or less, and the photosensitive silver salt is not positively added.

In the present invention, a solid dispersion apparatus and a technique used for performing the above dispersion method are described in, for example, “Dispersion Rheology and Dispersion Technique” (Toshio Kajiuchi, Hiroki Usui, 1991, Shinzansha Publishing Co., Ltd., p357
-P403), "The 24th Progress of Chemical Engineering", edited by The Society of Chemical Engineers, Tokai Branch, 1990, Maki Shoten, p184-p185),
Although detailed in the dispersing method of the present invention, the aqueous dispersion containing at least an organic silver salt is pressurized by a high-pressure pump or the like and sent into a pipe, and then passed through a narrow slit provided in the pipe, Thereafter, the dispersion is finely dispersed by causing an abrupt pressure drop in the dispersion.

The high-pressure homogenizer to which the present invention relates is generally composed of (a) a "shearing force" generated when the dispersoid passes through a narrow gap at a high pressure and at a high speed, and (b) a dispersoid is generated under a high pressure and a normal pressure. It is considered that the particles are dispersed into fine particles by a dispersing force such as "cavitation force" generated when the particles are released. As an example of this type of dispersing apparatus, a Gaulin homogenizer is mentioned in the past.In this apparatus, the liquid to be dispersed sent at a high pressure is converted into a high-speed flow through a narrow gap on a cylindrical surface, and the force is applied to the surrounding wall by the force. The particles collide and are emulsified and dispersed by the impact force. Working pressure is generally 10
0~600kg / cm ^2, the flow rate is in the range of a few M～30m / sec, be devised that the high flow rate portion was devised such increasing the number collisions in the saw-toothed in order to increase the dispersion efficiency I have. On the other hand, in recent years, apparatuses capable of dispersing at higher pressure and higher flow rate have been developed, and typical examples thereof include a microfluidizer (Microfluidex International Corporation) and a nanomizer (specialized machine). Industrial Co., Ltd.).

Examples of the dispersion apparatus suitable for the present invention include a microfluidizer M-110S-EH (with a G10Z interaction chamber), M-110Y (with a H10Z interaction chamber), and a microfluidizer manufactured by Microfluidex International Corporation. -140K (with G10Z interaction chamber), HC-5000 (with L30Z or H230Z interaction chamber), HC-8000 (with E230Z or L3
0Z interaction chamber).

Using these apparatuses, an aqueous dispersion containing at least an organic silver salt is pressurized by a high-pressure pump or the like and fed into a pipe, and then passed through a narrow slit provided in the pipe to obtain a desired pressure. Is applied, and thereafter, the pressure in the pipe is rapidly returned to the atmospheric pressure, for example, by causing a rapid pressure drop in the dispersion liquid, thereby making it possible to obtain an optimal organic silver salt dispersion for the present invention. .

It is preferable that the raw material liquid is preliminarily dispersed before the dispersion operation. As means for preliminary dispersion, known dispersion means (for example, high-speed mixer, homogenizer, high-speed impact mill, Banbury mixer, homomixer, kneader, ball mill, vibration ball mill, planetary ball mill, attritor, sand mill, bead mill, colloid mill,
Jet mill, roller mill, tron mill, high-speed stone mill) can be used. Instead of mechanically dispersing, fine particles may be formed by coarsely dispersing in a solvent by controlling the pH and then changing the pH in the presence of a dispersing agent. At this time, an organic solvent may be used as a solvent used for the coarse dispersion, and the organic solvent is usually removed after the completion of the fine particle formation.

In the organic silver salt dispersion of the present invention, the flow rate,
It is possible to disperse to the desired particle size by adjusting the pressure difference during pressure drop and the number of treatments.However, from the viewpoint of photographic characteristics and particle size, the flow rate is 200 m / sec to 600 m / sec, is preferably in the range pressure is 900~3000kg / cm ^2, flow rate 300
m / sec ～600M / sec, the pressure difference at the pressure drop 1500~3000kg / cm ²
More preferably, it is within the range. The number of times of the dispersion processing can be selected as needed, and usually 1 to 10 times is selected, but from the viewpoint of productivity, about 1 to 3 times is selected. It is not preferable to raise the temperature of such an aqueous dispersion under high pressure from the viewpoint of dispersibility and photographic characteristics.At a temperature higher than 90 ° C., the particle size tends to increase, and the fog tends to increase. is there. Therefore, in the present invention, the step before the conversion to the high pressure and high flow rate, the step after the pressure is reduced, or both of these steps include a cooling step, and the temperature of such water dispersion is reduced by the cooling step. It is preferably kept in the range of ~ 90 ° C,
More preferably, the temperature is maintained in the range of 5 to 80C, particularly preferably in the range of 5 to 65C. Especially, 1500-3000kg / cm ²
It is effective to provide the above cooling step at the time of high-pressure dispersion in the range described above. As the cooler, a double tube, a double tube using a static mixer, a multi-tube heat exchanger, a coiled tube heat exchanger, or the like can be appropriately selected according to the required heat exchange amount. Further, in order to increase the efficiency of heat exchange, it is sufficient to select a suitable one such as a pipe thickness, a wall thickness and a material in consideration of a working pressure. As the refrigerant used for the cooler, use 20 ° C well water, 5-10 ° C cold water treated with a refrigerator, and, if necessary, -30 ° C ethylene glycol / water refrigerant, etc., based on the heat exchange amount. You can also.

In the dispersion operation of the present invention, the organic silver salt is preferably dispersed in the presence of an aqueous solvent-soluble dispersant (dispersion aid). Examples of the dispersing agent include polyacrylic acid, a copolymer of acrylic acid, a maleic acid copolymer, a maleic acid monoester copolymer, a synthetic anionic polymer such as an acrylomethylpropanesulfonic acid copolymer, and carboxymethyl. Starch, semi-synthetic anionic polymers such as carboxymethyl cellulose, alginic acid, anionic polymers such as pectic acid, the compounds described in JP-A-7-350753, or known anionic, nonionic, cationic surfactants and other polyvinyl Known polymers such as alcohol, polyvinylpyrrolidone, carboxymethylcellulose, hydroxypropylcellulose, and hydroxypropylmethylcellulose, and naturally occurring polymer compounds such as gelatin can be appropriately selected and used. Le compounds, particularly preferred water-soluble cellulose derivatives.

It is a general method that the dispersing aid is mixed with the organic silver salt powder or the organic silver salt in a wet cake state before the dispersion, and then sent as a slurry to the dispersing machine. Heat treatment or treatment with a solvent may be performed in the combined state to obtain an organic silver salt powder or a wet cake. The pH may be controlled by a suitable pH adjuster before, during or after dispersion.

In addition to the mechanical dispersion, the particles may be coarsely dispersed in a solvent by controlling the pH, and then finely divided by changing the pH in the presence of a dispersing agent. At this time, an organic solvent may be used as a solvent used for the coarse dispersion, and the organic solvent is usually removed after the completion of the fine particle formation.

The prepared dispersion is stored with stirring for the purpose of suppressing sedimentation of fine particles during storage, or stored in a highly viscous state (for example, in a jelly state using gelatin) by means of a hydrophilic colloid. You can also.
Further, a preservative can be added for the purpose of preventing the propagation of various bacteria during storage.

The particle size (volume-weighted average diameter) of the organic silver salt solid fine particle dispersion of the present invention is determined, for example, by irradiating a solid fine particle dispersion dispersed in a liquid with a laser beam and changing the scattered light fluctuation with time. It can be obtained from the particle size (volume weighted average diameter) obtained by obtaining the autocorrelation function. A solid fine particle dispersion having an average particle size of 0.05 μm or more and 10.0 μm or less is preferable. The average particle size is more preferably 0.1 μm or more and 5.0 μm or less, and still more preferably the average particle size is 0.1 μm or more and 2.0 μm or less.

The particle size distribution of the organic silver salt is preferably monodispersed. Specifically, the percentage of the standard deviation of the volume-weighted average diameter divided by the volume-weighted average diameter (coefficient of variation)
Is 80% or less, more preferably 50% or less, still more preferably
30% or less.

The shape of the organic silver salt can be measured from a transmission electron microscope image of the organic silver salt dispersion.

The organic silver salt solid fine particle dispersion used in the present invention comprises at least an organic silver salt and water. The ratio between the organic silver salt and water is not particularly limited, but the ratio of the organic silver salt to the whole is preferably 5 to 50 wt%, particularly preferably 10 to 30 wt%. Although it is preferable to use the above-mentioned dispersing aid, it is preferable to use a minimum amount in a range suitable for minimizing the particle size 、,
It is preferably in the range of 1 to 30% by weight, particularly 3 to 15% by weight, based on the organic silver salt.

In the present invention, it is possible to produce a photosensitive material by mixing an aqueous dispersion of an organic silver salt and an aqueous dispersion of a photosensitive silver salt. Although it can be selected, the ratio of the photosensitive silver salt to the organic silver salt is preferably in the range of 1 to 30 mol%, more preferably 3 to 20 mol%, particularly preferably 5 to 15 mol%. Mixing two or more aqueous dispersions of organic silver salts with two or more aqueous dispersions of photosensitive silver salts during mixing is a method preferably used for adjusting photographic characteristics.

The organic silver salt of the present invention can be used in a desired amount, but the silver amount is preferably 0.1 to 5 g / m ² , more preferably 1 to 3 g / m ^{2 in} terms of the coating amount per m ^{2 of} the recording material. ²

The photosensitive silver halide used in the present invention is not particularly limited in the halogen composition, and silver chloride, silver chlorobromide, silver bromide, silver iodobromide, and silver iodochlorobromide can be used. . The distribution of the halogen composition in the grains may be uniform, the halogen composition may change stepwise, or may change continuously. Further, silver halide grains having a core / shell structure can be preferably used. The preferred structure is
The core has a double / five-layer structure, and more preferably has a double / four-layer structure.
Shell particles can be used. A technique for localizing silver bromide on the surface of silver chloride or silver chlorobromide grains can also be preferably used.

Methods for forming photosensitive silver halide are well known in the art, for example, Research Disclosure No. 17029, June 1978, and US Pat. No. 3,700,458.
Can be used.Specifically, a photosensitive silver halide is prepared by adding a silver-supplying compound and a halogen-supplying compound to a gelatin or other polymer solution, and then the organic silver halide is added. A method of mixing with a silver salt is used. The grain size of the photosensitive silver halide is
For the purpose of suppressing white turbidity after image formation, it is preferably small, specifically 0.20 μm or less, more preferably 0.1 μm or less.
01 μm or more and 0.15 μm or less, more preferably 0.02 μm or more
0.12 μm or less is preferred. Here, the grain size means the length of the edge of the silver halide grain when the silver halide grain is a cubic or octahedral so-called normal crystal. In the case where the silver halide grains are tabular grains, the diameter refers to a diameter when converted into a circular image having the same area as the projected area of the main surface. In the case of other than normal crystals, for example, in the case of spherical grains, rod-shaped grains, etc., it refers to the diameter of a sphere equivalent to the volume of silver halide grains.

The shape of the silver halide grains is cubic,
Octahedral, tabular particles, spherical particles, rod-like particles, potato-like particles and the like can be mentioned. In the present invention, cubic particles and tabular particles are particularly preferable. When the tabular silver halide grains are used, the average aspect ratio is preferably from 100: 1 to 2: 1, more preferably from 50: 1 to 3: 1. Further, grains having rounded corners of silver halide grains can also be preferably used. The surface index (mirror index) of the outer surface of the photosensitive silver halide grains is not particularly limited, but the spectral sensitizing efficiency when the spectral sensitizing dye is adsorbed is high. preferable.
The ratio is preferably 50% or more, more preferably 65% or more, and even more preferably 80% or more. The ratio of the Miller index {100} plane is determined by T. Tani; J. Imaging Sci., 29, 165 using the dependence of the adsorption of the sensitizing dye on the {111} and {100} planes.
(1985).

The light-sensitive silver halide grains of the present invention can be formed by using Group VII or VIII (Groups 7 to 10) of the periodic table.
Of a metal or metal complex. Rhodium, rhenium, ruthenium, osmium and iridium are preferred as the metal of Group VII or VIII of the periodic table or the central metal of the metal complex. One type of these metal complexes may be used, or two or more types of complexes of the same metal and different metals may be used in combination. The preferred content is 1 × 10 ^-9 per mole of silver.
1 × 10 ^-3 mols is preferable from the ^{molar, 1 × 10 - 8 1 ×} 10 -4 mol per mol of silver and more preferably from mol. As a specific structure of the metal complex, a metal complex having a structure described in JP-A-7-225449 or the like 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 ligand such as halogen, amines, oxalato, etc., for example, hexachlororhodium (III) complex salt, pentachloroacolodium (III) complex salt, tetrachlorodia Rhodium (III) complex salt, hexabromorhodium (II
I) complex salts, hexaammine rhodium (III) complex salts, trizalatrodium (III) complex salts and the like. These rhodium compounds are used by dissolving them in water or a suitable solvent. A method generally used to stabilize a solution of the rhodium compound, that is, a hydrogen halide aqueous solution (for example, hydrochloric acid, hydrobromic acid, hydrofluoric acid) Etc.) or a method of adding an alkali halide (eg, KCl, NaCl, KBr, NaBr, etc.). Instead of using water-soluble rhodium, it is also possible to add and dissolve other silver halide grains doped with rhodium during the preparation of silver halide.

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

These compounds can be appropriately added at the time of the production of silver halide emulsion grains and at each stage before coating the emulsion.
It is preferably incorporated into silver halide grains.

Rhenium, ruthenium and osmium used in the present invention are described in JP-A-63-2042 and JP-A-1-285941.
, 2-20852, 2-20855, etc. in the form of a water-soluble complex salt. Particularly preferred is a six-coordinate complex represented by the following formula. [ML ₆ ] ^n- where M represents Ru, Re or Os, L represents a ligand, n
Represents 0, 1, 2, 3 or 4.

In this case, the counter ion is not important, and an ammonium or alkali metal ion is used.

Preferred ligands include halide ligands, cyanide ligands, cyanide 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) C
^{_{l 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 1
It is preferably in the range of 1 × 10 ⁻⁹ mol to 1 × 10 ⁻⁵ mol per mol, particularly preferably 1 × 10 ⁻⁸ mol to 1 × 10 ⁻⁶ mol.

These compounds can be appropriately added at the time of production of silver halide emulsion grains and at each stage before coating the emulsion.
It is preferably incorporated into silver halide grains.

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

For addition to the surface of the particles, a required amount of an aqueous solution of a metal complex may be charged into the reaction vessel immediately after the formation of the particles, during or during physical ripening, or at the time of chemical ripening.

As the iridium compound used in the present invention, various compounds can be used. Examples thereof include hexachloroiridium, hexaammineiridium, trioxalatoiridium, hexacyanoiridium, and pentachloronitrosyliridium. These iridium compounds are used after being dissolved in water or a suitable solvent. However, a method generally used for stabilizing a solution of the iridium compound, that is, an aqueous solution of hydrogen halide (for example, hydrochloric acid, hydrobromic acid, hydrofluoric acid) is used. Etc.) or a method of adding an alkali halide (eg, KCl, NaCl, KBr, NaBr, etc.). Instead of using water-soluble iridium, it is also possible to add and dissolve another iridium-doped silver halide grain during silver halide preparation.

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

The above metal is 1 × 1 per mole of silver halide.
It is preferably from 0 ^-9 to 1 × 10 ^-4 mol. Further, in order to contain the above-mentioned metal, a metal salt in the form of a single salt, a double salt or a complex salt can be added at the time of preparing particles.

The photosensitive silver halide grains can be desalted by washing with water by a method known in the art such as a noodle method or a flocculation method, but in the present invention, it may or may not be desalted. .

As the gold sensitizer used for sensitizing the silver halide emulsion of the present invention to gold, the oxidation number of gold may be +1 or +3, and is usually used as a gold sensitizer. Gold compounds can be used. Representative examples include chloroauric acid, potassium chloroaurate, auric trichloride, potassium auric thiocyanate, potassium iodooleate, tetracyano auric acidide, ammonium aurothiocyanate, pyridyl trichlorogold and the like.

The amount of the gold sensitizer to be added varies depending on various conditions. As a guide, the amount is from 1 × 10 ^-7 mol to 1 × 10 ^-3 mol, more preferably 1 × 10 ^-6 mol, per mol of silver halide. It is not less than 5 mol and not more than 5 × 10 ^-4 mol.

The silver halide emulsion of the present invention is preferably used in combination with gold sensitization and another chemical sensitization. As other chemical sensitization methods, known methods such as a sulfur sensitization method, a selenium sensitization method, a tellurium sensitization method, and a noble metal sensitization method can be used. When used in combination with the gold sensitization method,
For example, sulfur sensitization and gold sensitization, selenium sensitization and gold sensitization, sulfur sensitization and selenium sensitization and gold sensitization, sulfur sensitization and tellurium sensitization and gold sensitization Preferred methods include sulfur sensitization, selenium sensitization, tellurium sensitization, and gold sensitization.

The sulfur sensitization preferably used in the present invention is
Usually, a sulfur sensitizer is added, and the emulsion is stirred at a high temperature of 40 ° C. or higher for a certain period of time. Known compounds can be used as the sulfur sensitizer.For example, in addition to sulfur compounds contained in gelatin, various sulfur compounds such as thiosulfates, thioureas, thiazoles, rhodanines and the like are used. be able to. Preferred sulfur compounds are thiosulfates and thiourea compounds. The addition amount of the sulfur sensitizer varies under various conditions such as the pH, temperature, and size of silver halide grains during chemical ripening.
It is 1 × 10 ⁻⁷ to 1 × 10 ⁻² mol per mol, and more preferably 1 × 10 ⁻⁵ to 1 × 10 ⁻³ mol.

As the selenium sensitizer used in the present invention, known selenium compounds can be used. That is, it is usually carried out by adding an unstable and / or non-unstable selenium compound and stirring the emulsion at a high temperature of 40 ° C. or higher for a certain period of time. As unstable selenium compounds, JP-B-44-15748, JP-B-43-13489, JP-A-4-25832,
The compounds described in JP-A Nos. 4-109240 and 4-324855 can be used. In particular, the general formula (VIII) in JP-A-4-324855
It is preferable to use the compound represented by (IX).

The tellurium sensitizer used in the present invention is a compound which forms silver telluride which is presumed to be a sensitizing nucleus on the surface or inside of silver halide grains. The formation rate of silver telluride in a silver halide emulsion is described in JP-A-5-3132.
It can be tested by the method described in No. 84. Examples of tellurium sensitizers include diacyl tellurides, bis (oxycarbonyl) tellurides, bis (carbamoyl) tellurides, diacyl tellurides, bis (oxycarbonyl) ditellurides, bis (carbamoyl) ditellurides, P = Te Compounds having a bond, tellurocarboxylates, Te-organyltellurocarboxylates, di (poly) tellurides,
Tellurides, tellurols, telluroacetals, tellurosulfonates, compounds having a P-Te bond, Te-containing heterocycles, tellurocarbonyl compounds, inorganic tellurium compounds,
Colloidal tellurium or the like can be used. Specifically, U.S. Patent Nos. 1,623,499, 3,320,069,
No. 772,031, British Patent No. 235,211 and No. 1,121,496,
No. 1,295,462, No. 1,396,696, Canadian Patent No. 800,
No. 958, JP-A-4-204640, Japanese Patent Application No. 3-53693, JP-A-3-31515
No. 98, No. 4-129787, Journal of Chemical Society Chemical Communication (J. Chem.
Soc. Chem. Commun.), 635 (1980), ibid, 1102 (1979), i
bid, 645 (1979), Journal of Chemical Society Parkin Transaction 1 (J. Chem. Soc.
Perkin.Trans.1), 2191 (1980), edited by S. Patai,
The Chemistry of Organic Selenium
And Tellurium Campounds
Organic Serenium and Tellunium Compounds), Vol. 1 (198
6), the compounds described in Vol. 2 (1987) can be used. In particular, JP-A-5-313284 discloses general formulas (II), (III) and (I).
Compounds represented by V) are preferred.

[0098] The amount of the selenium and tellurium sensitizers used in the present invention, the silver halide grains to be used, but the chemical ripening condition and the like and, generally 1 mol of silver halide per 1 × 10 ^-8 ~1 × 10 ^-2 mol, preferably 1 × 10 ^-7 to 1 × 10
^Use about ^-3 moles. 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.

In the silver halide emulsion used in the present invention, a cadmium salt, a sulfite, a lead salt, a thallium salt, and the like may be coexistent during the formation of silver halide grains or physical ripening.

In the present invention, reduction sensitization can be used. As specific compounds of the reduction sensitization method, in addition to ascorbic acid and thiourea dioxide, for example, stannous chloride, aminoiminomethanesulfinic acid, hydrazine derivatives, borane compounds, silane compounds, polyamine compounds and the like can be used. . Also, when the pH of the emulsion is 7 or more or p
Reduction sensitization can be achieved by aging while keeping Ag at 8.3 or less. Further, reduction sensitization can be achieved by introducing a single addition portion of silver ion during grain formation.

A thiosulfonic acid compound may be added to the silver halide emulsion of the present invention according to the method described in EP-A-293,917.

The silver halide emulsion in the recording material used in the present invention may be only one kind or two or more kinds (for example,
Those with different average grain sizes, different halogen compositions, different crystal habits, different chemical sensitization conditions)
You may use together.

The amount of the photosensitive silver halide used in the present invention is preferably 0.01 mol to 0.5 mol, more preferably 0.02 mol to 0.3 mol, and more preferably 0.03 mol to 1 mol of the organic silver salt. It is particularly preferably at least 0.25 mol but not more than 0.25 mol. Regarding the mixing method and the mixing conditions of the separately prepared photosensitive silver halide and organic silver salt, the prepared silver halide particles and organic silver salt are mixed with a high-speed stirrer, ball mill, sand mill, colloid mill, vibration mill, homogenizer, etc. There is a method of mixing, or a method of preparing an organic silver salt by mixing photosensitive silver halide prepared at any timing during the preparation of the organic silver salt,
There is no particular limitation as long as the effects of the present invention are sufficiently exhibited.

The time for adding the silver halide of the present invention to the coating solution for the image forming layer is preferably from 180 minutes to immediately before coating, and preferably from 60 minutes to 10 seconds before coating. Is not particularly limited as long as the effects of the present invention are sufficiently exhibited. As a specific mixing method, a method of mixing in a tank in which the average residence time calculated from the addition flow rate and the amount of liquid sent to the coater is set to a desired time, by N. Harnby, MFE Edwards, AW Nienow, translated by Koji Takahashi There is a method using a static mixer or the like described in Chapter 8 of "Liquid Mixing Technology" (published by Nikkan Kogyo Shimbun, 1989).

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

In a heat-developable recording material using an organic silver salt, a wide range of reducing agents are disclosed in JP-A-46-6074 and JP-A-47-1238.
47-33621, 49-46427, 49-115540, 50-14
No. 334, No. 50-36110, No. 50-147711, No. 51-32632,
No. 51-1023721, No. 51-32324, No. 51-51933, No. 52-8
4727, 55-108654, 56-146133, 57-82828
No. 57-82829, JP-A-6-3793, U.S. Pat.
No. 86, No. 3,679,426, No. 3,751,252, No. 3,751,255
Nos. 3,761,270, 3,782,949, 3,839,048,
3,928,686, 5,464,738, German patent 2321328,
It is disclosed in European Patent No. 692732 and the like. For example, phenylamide oxime, 2-thienylamide oxime and
Amide oximes such as p-phenoxyphenylamide oxime; azines such as 4-hydroxy-3,5-dimethoxybenzaldehyde azine; combinations of 2,2′-bis (hydroxymethyl) propionyl-β-phenylhydrazine with ascorbic acid Combinations of such aliphatic carboxylic acid aryl hydrazides with ascorbic acid; combinations of polyhydroxybenzene with hydroxylamine, reductone and / or hydrazine (e.g. hydroquinone, bis (ethoxyethyl) hydroxylamine, piperidinohexose reductone Or a combination of formyl-4-methylphenylhydrazine, etc.); phenylhydroxamic acid, p
Hydroxamic acids such as -hydroxyphenylhydroxamic acid and β-alinine hydroxamic acid; combinations of azines with sulfonamidophenols (eg, phenothiazine and 2,6-dichloro-4-benzenesulfonamidophenol); ethyl-α-cyano Α-cyanophenylacetic acid derivatives such as 2-methylphenylacetate and ethyl-α-cyanophenylacetate; 2,2′-dihydroxy-1,1′-binaphthyl, 6,6′-dibromo-2,2′-dihydroxy Bis-β-naphthol as exemplified by -1,1′-binaphthyl and bis (2-hydroxy-1-naphthyl) methane; bis-β-naphthol and 1,3-dihydroxybenzene derivatives (eg, 2,4
-Dihydroxybenzophenone or 2 ', 4'-dihydroxyacetophenone); 3-methyl-1-phenyl
5-pyrazolone, such as -5-pyrazolone; reductones as exemplified by dimethylaminohexose reductone, anhydrodihydroaminohexose reductone and anhydrodihydropiperidone hexose reductone;
Sulfonamidophenol reducing agents such as 2,6-dichloro-4-benzenesulfonamidophenol and p-benzenesulfonamidophenol; 2-phenylindane-1,3-
Diones and the like; chromanes such as 2,2-dimethyl-7-t-butyl-6-hydroxychroman; 1,4-dihydropyridines such as 2,6-dimethoxy-3,5-dicarboethoxy-1,4-dihydropyridine; Bisphenols (e.g., bis (2-hydroxy
-3-t-butyl-5-methylphenyl) methane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 4,4-ethylidene
-Bis (2-t-butyl-6-methylphenol), 1,1-bis (2-
Hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane and 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane and the like; ascorbic acid derivatives (for example, 1-palmitic acid) And aldehydes and ketones such as benzyl and biacetyl; 3-pyrazolidone and certain indan-1,3-diones; chromanol (such as tocopherol). Particularly preferred reducing agents are bisphenol and chromanol.

The reducing agent of the present invention may be added by any method such as a solution, a powder, and a dispersion of solid fine particles. The dispersion of the solid fine particles is carried out by a known means for making fine (for example, a ball mill, a vibration ball mill, a sand mill, a colloid mill, a jet mill, a roller mill, etc.). When dispersing the solid fine particles, a dispersing aid may be used.

When an additive known as a "toning agent" for improving an image is included, the optical density may be increased. Toning agents may also be advantageous in forming black silver images. The toning agent is preferably contained in an amount of 0.1 to 50 mol% per mol of silver on the surface having the image forming layer, and 0.1 to 50 mol%.
More preferably, the content is 5 to 20 mol%. Further, the toning agent may be a so-called precursor which is derivatized so as to have a function effectively only during development.

In a heat-developable recording material using an organic silver salt, a wide range of toning agents are disclosed in JP-A-46-6077 and JP-A-47-10282.
Nos. 49-5019, 49-5020, 49-91215, 49-9
No. 1215, No. 50-2524, No. 50-32927, No. 50-67132,
No. 50-67641, No. 50-114217, No. 51-3223, No. 51-279
No. 23, No. 52-14788, No. 52-99813, No. 53-1020, No. 5
3-76020, 54-156524, 54-156525, 61-1836
No. 42, JP-A-4-56848, JP-B-49-10727, 54-2033
No. 3, U.S. Pat.Nos. 3,080,254, 3,446,648, 3,782,9
No. 41, No. 4,123,282, No. 4,510,236, British Patent 138079
No. 5, Belgian Patent No. 841910 and the like. Examples of toning agents are phthalimide and N-hydroxyphthalimide; succinimide, pyrazolin-5-one and quinazolinone, 3-phenyl-2-pyrazolin-5-one, 1-phenylurazole, quinazoline and 2,4-thiazolidinedione Cyclic imides such as; naphthalimides (eg, N
-Hydroxy-1,8-naphthalimide); cobalt complexes (eg, cobalt hexamine trifluoroacetate); 3-
Mercapto-1,2,4-triazole, 2,4-dimercaptopyrimidine, 3-mercapto-4,5-diphenyl-1,2,4-triazole and 2,5-dimercapto-1,3,4-thiadiazole Illustrative mercaptans; N- (aminomethyl) aryldicarboximides, such as (N, N-dimethylaminomethyl) phthalimide and N, N- (dimethylaminomethyl)-
Naphthalene-2,3-dicarboximide); and blocked pyrazoles, isothiuronium derivatives and certain photobleaching agents (eg, N, N′-hexamethylenebis (1-carbamoyl-3,5-dimethylpyrazole), 1 , 8- (3,6-diazaoctane) bis (isothiuronium trifluoroacetate) and 2-tribromomethylsulfonyl)-(benzothiazole)); and 3-ethyl-5 [(3-ethyl-2-benzothia) Zolinylidene) -1-methylethylidene] -2-thio-2,4-oxazolidinedione; phthalazinone, phthalazinone derivative or metal salt, or 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7- Derivatives such as dimethoxyphthalazinone and 2,3-dihydro-1,4-phthalazinedione; phthalazinone and phthalic acid derivatives (for example, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic acid) Combination of anhydride such as phthalic acid); phthalazine, phthalazine derivatives or metal salts or 4- (1-naphthyl)
Derivatives such as phthalazine, 6-isopropylphthalazine, 6-tert-butylphthalazine, 6-chlorophthalazine, 5,7-dimethoxyphthalazine and 2,3-dihydrophthalazine;
Combinations of phthalazines and phthalic acid derivatives (e.g., phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic anhydride, etc.); quinazolinedione, benzoxazine or naphthoxazine derivatives; Rhodium complexes that also function in situ as sources of halide ions for silver halide formation, such as ammonium hexachlororhodate (III), rhodium bromide, rhodium nitrate and hexachlororhodium (I
II) potassium acid and the like; inorganic peroxides and persulfates, such as ammonium disulfide and hydrogen peroxide;
Benzoxazine-2 such as 3-benzoxazine-2,4-dione, 8-methyl-1,3-benzoxazine-2,4-dione and 6-nitro-1,3-benzoxazine-2,4-dione Pyrimidines and asymmetric-triazines (eg, 2,4-dihydroxypyrimidine, 2-hydroxy-4-aminopyrimidine, etc.), azauracil, and tetraazapentalene derivatives (eg, 3,6-dimercapto-1) , 4-diphenyl-1
H, 4H-2,3a, 5,6a-tetraazapentalene, and 1,4-di
(o-chlorophenyl) -3,6-dimercapto-1H, 4H-2,3a, 5,6
a-tetraazapentalene).

The color-toning agent of the present invention may be added by any method such as a solution, a powder and a dispersion of solid fine particles. The dispersion of the solid fine particles is carried out by a known means for making fine (for example, a ball mill, a vibration ball mill, a sand mill, a colloid mill, a jet mill, a roller mill, etc.). When dispersing the solid fine particles, a dispersing aid may be used.

As the sensitizing dye in the present invention, any dye can be used as long as it can spectrally sensitize silver halide grains in a desired wavelength range when adsorbed on silver halide grains. As the sensitizing dye, a cyanine dye, a merocyanine dye, a complex cyanine dye, a complex merocyanine dye, a holopolar cyanine dye, a styryl dye, a hemicyanine dye, an oxonol dye, a hemioxonol dye, and the like can be used. Useful sensitizing dyes for use in the present invention include, for example, RESEARCH DISCLOSURE Item 17
Item 643IV-A (p.23, December 1978), Item 1831X (August 1979)
p.437) or in the literature cited. In particular, a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of the light source of various laser imagers, scanners, imagesetters and plate making cameras can be advantageously selected.

Examples of spectral sensitization to red light include He-Ne
For a so-called red light source such as a laser, a red semiconductor laser or an LED, a compound of I-1 to I-38 described in JP-A-54-18726, and a compound of I-1 described in JP-A-6-75322. I-3
5 and the compounds I-1 to I- described in JP-A-7-287338.
34 compounds, dyes 1 to 20 described in JP-B-55-39818,
The compounds I-1 to I-37 described in JP-A-62-284343 and the compounds I-1 to I-34 described in JP-A-7-287338 are advantageously selected.

For a semiconductor laser light source in the wavelength range of 750 to 1400 nm, various known dyes including cyanine, merocyanine, styryl, hemicyanine, oxonol, hemioxonol and xanthene dyes are spectrally advantageously sensitized. Can be done. Useful cyanine dyes are, for example, cyanine dyes having basic nuclei such as thiazoline nuclei, oxazoline nuclei, pyrroline nuclei, pyridine nuclei, oxazole nuclei, thiazole nuclei, selenazole nuclei and imidazole nuclei. Preferred useful merocyanine dyes include, in addition to the above basic nuclei, acidic nuclei such as thiohydantoin nucleus, rhodanine nucleus, oxazolidinedione nucleus, thiazolinedione nucleus, barbituric acid nucleus, thiazolinone nucleus, malononitrile nucleus and pyrazolone nucleus. Including. Among the above cyanine and merocyanine dyes, those having an imino group or a carboxyl group are particularly effective. For example, U.S. Patent 3,761,279,
3,719,495 and 3,877,943, British Patent 1,466,201
No. 1,469,117, No. 1,422,057, Tokuhei 3-10391
No. 6-52387, JP-A-5-341432, 6-94781,
It may be appropriately selected from known dyes as described in JP-A-6-301141.

Particularly preferred structures of the dyes used in the present invention are cyanine dyes having a thioether bond-containing substituent (see, for example, JP-A-62-58239 and JP-A-3-13863).
No.8, No.3-138642, No.4-255840, No.5-72659, No.5-
72661, 6-222491, 2-230506, 6-258757
No., 6-317868, 6-324425, Tokuyohei 7-500926,
Dyes described in U.S. Pat.No. 5,541,054), dyes having a carboxylic acid group (for example, JP-A-3-163440, 6-301
No. 141, dyes described in U.S. Pat.No. 5,441,899), merocyanine dyes, polynuclear merocyanine dyes and polynuclear cyanine dyes (JP-A-47-6329, JP-A-49-105524, JP-A-51-127719,
No. 52-80829, No. 54-61517, No. 59-214846, No. 60-67
No. 50, 63-159841, JP-A-6-35109, 6-59381
No., 77-146537, 77-146537, Tokuyohei 55-50111,
Dyes described in British Patent 1,467,638 and US Patent 5,281,515).

Further, dyes described in Example 5 of US Pat. Nos. 5,510,236 and 3,871,887 as dyes forming J-band
JP-A-2-96131 and JP-A-59-48753 are disclosed and can be preferably used in the present invention.

These sensitizing dyes may be used alone.
Two or more kinds may be used in combination. Combinations of sensitizing dyes are often used, especially for supersensitization. Along with the sensitizing dye, the emulsion may contain a dye which does not itself have a spectral sensitizing effect or a substance which does not substantially absorb visible light and exhibits supersensitization. Useful sensitizing dyes, combinations of dyes exhibiting supersensitization and substances exhibiting supersensitization are
Research Disclosure Volume 176, 17643 (December 1978) No. 23
Section IV of Page IV, or JP-B-49-25500, 43-43933,
These are described in JP-A-59-19032 and JP-A-59-192242.

The sensitizing dyes may be added to the silver halide emulsion by dispersing them directly in the emulsion or by adding water, methanol, ethanol, propanol, acetone, methylcellosolve, 2,2, 3,3-tetrafluoropropanol, 2,2,2-trifluoroethanol, 3-methoxy
It may be added to the emulsion by dissolving it in a solvent such as 1-propanol, 3-methoxy-1-butanol, 1-methoxy-2-propanol, N, N-dimethylformamide, alone or in a mixed solvent.

As disclosed in US Pat. No. 3,469,987, a dye is dissolved in a volatile organic solvent, and this solution is dispersed in water or a hydrophilic colloid. To Japanese Patent Publication No. 44-23389,
As disclosed in JP-A-44-27555 and JP-A-57-22091, a dye is dissolved in an acid and this solution is added to the emulsion, or an acid or base is added to the emulsion as an aqueous solution in the presence of an acid or base. A method of adding an aqueous solution or a colloidal dispersion in the presence of a surfactant to an emulsion as disclosed in U.S. Patent Nos. 3,822,135 and 4,006,025, JP-A-51-746, a method in which a dye is directly dispersed in a hydrophilic colloid and the dispersion is added to an emulsion as disclosed in JP-A-51-746.
As disclosed in JP-A No. 24, a method of dissolving a dye using a compound that causes a red shift and adding this solution to an emulsion can also be used. Also, ultrasonic waves can be used for dissolution.

The sensitizing dye used in the present invention may be added to the silver halide emulsion of the present invention at any time during the preparation of the emulsion which has been found to be useful. For example, U.S. Patents 2,735,766 and 3,628,960,
4,183,756, 4,225,666, JP-A-58-184142,
As disclosed in the specification of JP-A-60-196749 and the like, the stage before silver halide grain formation step or / and desalination, during and / or after desalination step and before the start of chemical ripening. As disclosed in the specification such as JP-A-58-113920, any time immediately before chemical ripening or during the process, after chemical ripening, and before coating the emulsion before coating It may be added at the time and in the process.
Further, as disclosed in the specification of U.S. Pat. No. 4,225,666, JP-A-58-7629, etc., the same compound may be used alone or in combination with a compound having a different structure, for example, during the particle forming step. The compound may be divided and added during the ripening step or after the completion of the chemical ripening, or may be added separately before or during the chemical ripening or after the completion of the chemical ripening. May be added.

The amount of the sensitizing dye used in the present invention may be a desired amount in accordance with the performance such as sensitivity and fog.
The amount is preferably from 10 ^-6 to 1 mol, more preferably from 10 ^-4 to 10 ^-1 mol, per mol of silver halide in the photosensitive layer.

The silver halide emulsion according to the present invention or /
And the organic silver salts can be further protected against the formation of additional fog by antifoggants, stabilizers and stabilizer precursors, and can be stabilized against reduced sensitivity during storage in inventory. Suitable antifoggants, stabilizers and stabilizer precursors that can be used alone or in combination are the thiazonium salts described in U.S. Pat.Nos. 2,131,038 and 2,694,716, U.S. Pat. Azaindene, U.S. Pat.
No. 28,663, mercury salt, U.S. Pat.No.3,287,135, urazole, U.S. Pat.No. 3,235,652, sulfocatechol, British Patent No.
No. 405, polyvalent metal salts, U.S. Pat.No. 3,220,839, thyuronium salts, and U.S. Pat. Halogen-substituted organic compounds described in 4,442,202, U.S. Pat.
No. 7, No. 4,137,079, No. 4, 138, 365 and No.
No. 4,459,350 triazine and U.S. Pat.
And the phosphorus compounds described in JP-A-11,985.

The antifoggant preferably used in the present invention is an organic halide.
No. 50-120328, No. 51-121332, No. 54-58022, No.
56-70543, 56-99335, 59-90842, 61-12964
No. 2, 62-129845, JP-A-6-208191, 7-5621,
Nos. 7-2781, 8-15809, U.S. Pat.
Compounds such as those disclosed in US Pat.

The antifoggant of the present invention may be added by any method such as a solution, a powder, and a dispersion of solid fine particles. The dispersion of the solid fine particles is carried out by a known means for making fine (for example, a ball mill, a vibration ball mill, a sand mill, a colloid mill, a jet mill, a roller mill, etc.). When dispersing the solid fine particles, a dispersing aid may be used.

Although not required to practice the present invention,
It may be advantageous to add a mercury (II) salt as an antifoggant to the emulsion layer. Preferred mercury (II) salts for this purpose are
Mercury acetate and mercury bromide. The amount of mercury used in the present invention is preferably 1 × 10 ⁻⁹ mol to 1 × 10 ⁻³ mol, more preferably 1 × 10 ⁻³ mol, per mol of the coated silver.
The range is from ^-9 mol to 1 × 10 ^-4 mol.

The heat-developable recording material of the present invention may contain benzoic acids for the purpose of increasing the sensitivity and preventing fog. The benzoic acids of the present invention may be any benzoic acid derivative, but examples of preferred structures include those described in U.S. Pat.
No. 9, No. 4, 152, 160, Japanese Patent Application No. 8-151242, No. 8-151241
And the compounds described in JP-A-8-98051 and the like. The benzoic acid of the present invention may be added to any part of the light-sensitive material, but it is preferable to add the benzoic acid to the layer having the photosensitive layer (image forming layer), and to add it to the organic silver salt-containing layer. More preferably, The benzoic acid of the present invention may be added at any time during the preparation of the coating solution, and when it is added to the organic silver salt-containing layer, it may be added at any time from the preparation of the organic silver salt to the preparation of the coating solution. It is preferable after salt preparation and immediately before application. The benzoic acid of the present invention may be added by any method such as powder, solution, and fine particle dispersion. Further, it may be added as a solution mixed with other additives such as a sensitizing dye, a reducing agent and a color tone agent.
The benzoic acid of the present invention may be added in any amount, but is preferably from 1 × 10 ⁻⁶ mol to 2 mol, more preferably from 1 × 10 ⁻³ mol to 0.5 mol, per mol of silver.

In the present invention, a mercapto compound, a disulfide compound, and a thione compound are contained in order to control development by suppressing or accelerating development, to improve spectral sensitization efficiency, to improve storage stability before and after development, and the like. be able to.

When a mercapto compound is used in the present invention, it may have any structure, but it may be Ar-SM or Ar-SSA.
Those represented by r are preferred. In the formula, M is a hydrogen atom or an alkali metal atom, and Ar is an aromatic ring group or a condensed aromatic ring group having one or more nitrogen, sulfur, oxygen, selenium or tellurium atoms. Preferably, the heteroaromatic ring in these groups is benzimidazole, naphthimidazole, benzothiazole, naphthothiazole, benzoxazole, naphthoxazole, benzoselenazole, benzotellurazole, imidazole, oxazole, pyrazole, triazole, thiadiazole, tetrazole, Triazine, pyrimidine, pyridazine, pyrazine, pyridine, purine, quinoline or quinazolinone. The heteroaromatic ring includes, for example, halogens (e.g., Br and Cl), hydroxy, amino, carboxy,
Alkyl (e.g. one or more carbon atoms, preferably 1-4
Having one carbon atom) and alkoxy (e.g.,
One having at least one carbon atom, preferably having 1 to 4 carbon atoms). Examples of the mercapto-substituted heteroaromatic compound include 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole,
Mercapto-5-methylbenzimidazole, 6-ethoxy-
2-mercaptobenzothiazole, 2,2'-dithiobis-benzothiazole, 3-mercapto-1,2,4-triazole, 4,5
-Diphenyl-2-imidazolethiol, 2-mercaptoimidazole, 1-ethyl-2-mercaptobenzimidazole, 2-mercaptoquinoline, 8-mercaptopurine, 2-mercapto-4 (3H) -quinazolinone, 7-trifluoromethyl-
4-quinolinethiol, 2,3,5,6-tetrachloro-4-pyridinethiol, 4-amino-6-hydroxy-2-mercaptopyrimidine monohydrate, 2-amino-5-mercapto-1,3,4 -
Thiadiazole, 3-amino-5-mercapto-1,2,4-triazole, 4-hydroxysil-2-mercaptopyrimidine, 2-mercaptopyrimidine, 4,6-diamino-2-mercaptopyrimidine, 2-mercapto-4-methyl Pyrimidine hydrochloride, 3-mercapto-5-phenyl-1,2,4-triazole,
Examples include 2-mercapto-4-phenyloxazole, but the present invention is not limited thereto.

The addition amount of these mercapto compounds is 0.001 to 1.0 per mol of silver in the emulsion layer (image forming layer).
A molar range is preferred, more preferably from 0.01 to 0.3 mole per mole of silver.

In the image forming layer (photosensitive layer) of the present invention, a polyhydric alcohol (for example, glycerin and diol of the type described in US Pat. No. 2,960,404) as a plasticizer and a lubricant, and US Pat. No. 2,588,765. And fatty acids or esters described in US Pat. No. 3,121,060 and silicone resins described in British Patent No. 955,061.

In the present invention, a super-high contrast agent can be used for forming a super-high contrast image. For example, U.S. Patent No. 5,464,73
No. 8, No. 5,496,695, No. 6,512,411, No. 5,536,622,
Japanese Patent Application Nos. Hei 7-228627, Hei 8-215822, Hei 8-130842
Nos. 8-148113, 8-156378, 8-148111, 8-
The hydrazine derivative described in 148116, the compound having a quaternary nitrogen atom described in Japanese Patent Application No. 8-83566, and the acrylonitrile compound described in US Pat. No. 5,545,515 can be used. Specific examples of the compound include compounds 1 to 10 and 5,49 of the aforementioned U.S. Patent No. 5,464,738.
H-1 to H-28 of 6,695, I-1 to I-8 of Japanese Patent Application No. 8-215822
6, H-1 to H-62 of 8-130842, 1-1 to 1-2 of 8-148113
1, 1 to 50 of 8-148111, 1 to 40 of 8-148116, 8 to 8
No. 3,566, P-1 to P-26, and T-1 to T-18, U.S. Pat.
No. 5,515, CN-1 to CN-13 and the like.

Further, the present invention provides a method for forming a super-high contrast image.
A high contrast accelerator can be used in combination with the above-mentioned super-high contrast agent. For example, amine compounds described in U.S. Pat.No. 5,545,505, specifically AM-1 to AM-5, hydroxamic acids described in 5,545,507, specifically HA-1 to HA-11, and the like.
Acrylonitrile described in 5,545,507, specifically C
Hydrazine compounds described in N-1 to CN-13 and 5,558,983, specifically CA-1 to CA-6, onium salts described in Japanese Patent Application No. 8-132836, specifically A-1 to A-42, B-1 to
B-27, C-1 to C-14 and the like can be used.

The synthesis method, addition method, addition amount and the like of these super-high contrast agents and high-contrast accelerators can be carried out as described in each of the cited patents.

The heat-developable recording material of the present invention may be provided with a surface protective layer for the purpose of preventing adhesion of the image forming layer.

The binder for the surface protective layer of the present invention may be any polymer, but preferably contains a polymer having a carboxylic acid residue in an amount of from 100 mg / m ^{2 to} 5 g / m ² . Examples of the polymer having a carboxyl residue include natural polymers (gelatin, alginic acid, etc.), modified natural polymers (carboxymethylcellulose, phthalated gelatin, etc.), synthetic polymers (polymethacrylate, polyacrylate, polyalkyl methacrylate / acrylate). Copolymer, polystyrene / polymethacrylate copolymer, etc.). The carboxy residue content of such a polymer is preferably from 1 × 10 ⁻² mol to 1.4 mol per 100 g of the polymer. Further, the carboxylic acid residue may form a salt with an alkali metal ion, an alkaline earth metal ion, an organic cation, or the like.

As the surface protective layer of the present invention, any anti-adhesion material may be used. Examples of anti-adhesion materials include waxes, silica particles, styrene-containing elastomeric block copolymers (e.g., styrene-butadiene-
Styrene, styrene-isoprene-styrene), cellulose acetate, cellulose acetate butyrate, cellulose propionate, and mixtures thereof. Further, a crosslinking agent for crosslinking and a surfactant for improving coating properties may be added to the surface protective layer.

In the image forming layer or the protective layer of the image forming layer in the present invention, US Pat. Nos. 3,253,921 and 2,27
Light absorbing substances and filter dyes as described in 4,782, 2,527,583 and 2,956,879 can be used. Also, for example, U.S. Pat.
The dye can be mordanted as described in US Pat. As the amount of filter dye used, the absorbance at the exposure wavelength is 0.
It is preferably from 1 to 3.0, and particularly preferably from 0.2 to 1.5.

The image-forming layer or the protective layer of the image-forming layer in the present invention may comprise a matting agent, for example, starch, titanium dioxide, zinc oxide, silica, of the type described in US Pat. Nos. 2,992,101 and 2,701,245. Polymer beads, including beads, can be included. The matt degree of the emulsion surface may be any value as long as stardust failure does not occur, but the Beck smoothness is preferably 50 seconds or more and 10,000 seconds or less, and particularly preferably 80 seconds or more and 10,000 seconds or less.

The preparation temperature of the coating solution for the image forming layer of the present invention is 30.
It is preferable that the temperature is not less than 65 ° C and not more than 35 ° C.
It is not less than 60 ° C. (preferably 55 ° C. or less). Also,
The temperature of the coating solution for the image forming layer immediately after the addition of the polymer latex is preferably maintained at 30 ° C. or more and 65 ° C. or less. Preferably, the reducing agent and the organic silver salt are mixed before the addition of the polymer latex.

The fluid containing the organic silver salt or the coating solution for the thermal image forming layer in the present invention is preferably a so-called thixotropic fluid. The thixotropic property refers to a property in which the viscosity decreases as the shear rate increases. Although any apparatus may be used for the viscosity measurement of the present invention, an RFS fluid spectrometer manufactured by Rheometrics Far East Co., Ltd. is preferably used and is measured at 25 ° C. Here, the organic silver salt-containing fluid or thermal image forming layer coating solution of the present invention has a viscosity at a shear rate of 0.1 S ^-1 of 400 mPas.
It is preferably at least 100,000 mPas or less, more preferably
It is 500 mPa · s or more and 20,000 mPa · s or less. Further, at a shear rate of 1000 S ^−1, it is preferably from 1 mPa · s to 200 mPa · s, and more preferably from 5 mPa · s to 80 mPa · s.

Various systems expressing thixotropy are known, and are described in “Lecture / Rheology”, edited by Polymer Publishing Association, Muroi,
It is described in Morino co-authored "Polymer Latex" (published by the Society of Polymer Publishing). In order for a fluid to exhibit thixotropic properties, it is necessary to contain a large amount of solid fine particles.
In order to enhance the thixotropic property, it is effective to include a thickened linear polymer, to increase the aspect ratio of the contained solid fine particles in an anisotropic shape, to use an alkali thickener, and to use a surfactant.

The photothermographic emulsion of the present invention comprises one or more layers on a support. One layer construction must include optional additional materials such as organic silver salts, silver halides, developers and binders, and toning agents, coating aids and other auxiliaries. The two-layer configuration is the first
It must contain the organic silver salt and silver halide in the emulsion layer (usually the layer adjacent to the support) and some other components in the second or both layers. However, a two-layer construction comprising a single emulsion layer containing all components and a protective topcoat is also contemplated. The construction of a multicolor photothermographic material may include a combination of these two layers for each color, and may include all components in a single layer as described in U.S. Pat.No. 4,708,928. Is also good. In the case of a multi-dye, multi-color photothermographic material, each emulsion layer is generally, as described in U.S. Pat.No. 4,460,681,
By using a functional or non-functional barrier layer between each emulsion layer (photosensitive layer), it is kept distinct from each other.

Various dyes and pigments can be used in the photosensitive layer of the present invention from the viewpoint of improving color tone and preventing irradiation. Dyes and pigments used in the photosensitive layer of the present invention may be any, for example, pigments and dyes described in the color index, specifically, pyrazoloazole dye, anthraquinone dye, azo dye, azomethine dye,
Organic dyes such as oxonol dyes, carbocyanine dyes, styryl dyes, triphenylmethane dyes, indoaniline dyes and indophenol dyes, azo pigments, polycyclic pigments (phthalocyanine pigments, anthraquinone pigments, etc.), dyeing lake pigments, Organic pigments including azine pigments, inorganic pigments and the like can be mentioned. Preferred dyes used in the present invention include anthraquinone dyes (e.g., compounds 1 to 9 described in JP-A-5-341441, compounds 3-6 to 18 and 3-23 to 38 described in JP-A-5-165147), azomethine Dyes (e.g., compounds 17 to 47 described in JP-A-5-341441), indoaniline dyes (e.g., compound 1 described in JP-A-5-289227)
1 to 19, compound 47 described in JP-A-5-341441, JP-A-5-165
No. 147 described compounds 2-10 to 11) and azo dyes (compounds 10 to 16 described in JP-A-5-341441) are preferred as anthraquinone-based indanthrone pigments (CI Pi
gment Blue 60), phthalocyanine pigments (CIPigment
Copper phthalocyanine such as Blue 15, CI Pigment Blue 16
Metal-free phthalocyanine, etc.), dyed lake pigment based triarylcarbonyl pigments, indigo, inorganic pigments
(Ultra blue, cobalt blue, etc.). As a method for adding these dyes and pigments, any method such as a solution, an emulsion, a solid fine particle dispersion, and a state in which the dye or pigment is mordanted with a polymer mordant may be used. The amount of these compounds used is determined by the target absorption, but generally 1 μg / m ² of recording material
It is preferable to use it in a range of not less than 1 g and not more than 1 g. In addition, dioxane-based pigments, quinacridone-based pigments,
Diketopyrrolopyrrole pigments and the like may be used in combination.

In the present invention, the antihalation layer can be provided on the side farther from the light source than the photosensitive layer. The antihalation layer preferably has a maximum absorption in a desired wavelength range of 0.3 or more and 2 or less, more preferably an absorption of an exposure wavelength of 0.5 or more and 2 or less, and an absorption in a visible region after processing of 0.001 or more. It is preferably less than 0.5, and more preferably a layer having an optical density of 0.001 or more and less than 0.3.

When antihalation dyes are used in the present invention, these dyes have the desired absorption in the wavelength range, have a sufficiently low absorption in the visible region after treatment, and have the desired absorbance spectrum shape of the antihalation layer. Any compound can be used as long as it is possible. For example, the following are disclosed, but the present invention is not limited thereto. As a single dye, JP-A-59-56458, JP-A-Hei 2-
216140, 7-13295, 711432, U.S. Patent 5,380,
No. 635, JP-A-2-68539, page 13, lower left column, line 1 to page 14, lower left column, line 9, and JP-A-3-24539, page 14, lower left column, page 16, lower right column The dyes that can be decolorized by the treatment include JP-A-52-139136, JP-A-53-132334, and
56-501480, 57-16060, 57-68831, 57-1018
No. 35, 59-182436, JP-A-7-36145, 7-199409
No., JP-B-48-33692, JP-B-50-16648, JP-B2-41734
Nos., U.S. Pat.Nos. 4,088,497, 4,283,487, 4,548,89
No. 6 and 5,187,049.

The heat-developable recording material of the present invention has at least one image forming layer (photosensitive layer) containing a silver halide emulsion on one side of a support, and has a back layer on the other side. It is preferably a so-called single-sided recording material.

In the present invention, a matting agent may be added to the single-sided recording material in order to improve transportability. The matting agent is generally fine particles of an organic or inorganic compound insoluble in water. Any matting agent can be used, for example, U.S. Patent Nos. 1,939,213, 2,701,245, and 2,322,037.
No. 3,262,782, No. 3,539,344, No. 3,767,448, etc.
2,192,241, 3,257,206, 3,370,951, 3,52
Inorganic matting agents well-known in the art, such as inorganic matting agents described in the respective specifications such as 3,022 and 3,769,020, can be used. For example, specifically, examples of organic compounds that can be used as a matting agent include, as examples of water-dispersible vinyl polymers, polymethyl acrylate, polymethyl methacrylate, polyacrylonitrile, acrylonitrile-α-methylstyrene copolymer, and polystyrene. , Styrene-divinylbenzene copolymer, polyvinyl acetate, polyethylene carbonate, polytetrafluoroethylene, etc., examples of cellulose derivatives such as methylcellulose,
Examples of starch derivatives such as cellulose acetate, cellulose acetate propionate, carboxy starch, carboxynitrophenyl starch, urea-formaldehyde-
Gelatin hardened with a known hardener such as a starch reactant and hardened gelatin obtained by coacervate hardening to form fine capsule hollow particles can be preferably used. As examples of the inorganic compound, silicon dioxide, titanium dioxide, magnesium dioxide, aluminum oxide, barium sulfate, calcium carbonate, silver chloride desensitized by a known method, silver bromide, glass, and diatomaceous earth can be preferably used. The above matting agents can be used by mixing different types of substances as necessary. The size and shape of the matting agent are not particularly limited, and those having an arbitrary particle size can be used. In practicing the present invention, it is preferable to use one having a particle size of 0.1 μm to 30 μm. Further, the particle size distribution of the matting agent may be narrow or wide. On the other hand, since the matting agent greatly affects the haze of the coating film and the surface gloss, the particle size, shape, and particle size distribution can be adjusted as necessary during the preparation of the matting agent or by mixing a plurality of matting agents. preferable.

In the present invention, the back layer has a matte degree of Beck's smoothness of preferably 1200 seconds or less and 10 seconds or more, more preferably 700 seconds or less and 50 seconds or more.

In the present invention, the matting agent is preferably contained in the outermost surface layer of the recording material, a layer functioning as the outermost surface layer, or a layer close to the outer surface. It is preferable to be contained.

In the present invention, suitable binders for the back layer are transparent or translucent, generally colorless, and include natural polymer synthetic resins, polymers and copolymers, and other film-forming media such as: gelatin, gum arabic, and poly (vinyl). (Alcohol), hydroxyethylcellulose, cellulose acetate, cellulose acetate butyrate, poly (vinylpyrrolidone), casein, starch, poly (acrylic acid), poly (methylmethacrylic acid), poly (vinyl chloride), poly (methacrylic acid), copoly (Styrene-maleic anhydride), copoly (styrene-acrylonitrile), copoly (styrene-butadiene), poly (vinylacetal) s (e.g., poly (vinylformal) and poly (vinylformal))
(Vinyl butyral)), poly (ester) s, poly (urethanes), phenoxy resin, poly (vinylidene chloride), poly (vinylidene chloride)
(Epoxides), poly (carbonates), poly (vinyl acetate), cellulose esters, and poly (amides). The binder may be coated from water or an organic solvent or emulsion.

In the present invention, the back layer preferably has a maximum absorption of 0.3 or more and 2 or less in a desired wavelength range.
More preferably absorption is 0.5 or more and 2 or less, and the absorption in the visible region after the treatment is preferably 0.001 or more and less than 0.5, and more preferably a layer having an optical density of 0.001 or more and less than 0.3. . Examples of the antihalation dye used in the back layer are the same as those of the antihalation layer described above.

US Pat. Nos. 4,460,681 and 4,374,9
Backside resistive heating layer as shown in No. 21
stive heating layer) can also be used in a photosensitive heat developed photographic image system.

A hardening agent may be used in each of the layers such as the image forming layer (photosensitive layer), the protective layer and the back layer according to the invention. Examples of hardeners include “THE THEORY OF THE PHOTO” by THJames.
GRAPHIC PROCESS FOURTH EDITION "(Macmillan Publishi
ng Co., Inc., published in 1977) There are various methods described on pages 77 to 87, polyvalent metal ions described on page 78 of the same book, U.S. Pat.No. 4,281,060, and polyisocyanates such as JP-A-6-208193. , Epoxy compounds such as US Pat. No. 4,791,042, and vinyl sulfone compounds such as JP-A-62-89048 are preferably used.

The hardening agent is added as a solution, and the time of adding this solution to the coating solution for the protective layer is from 180 minutes to immediately before coating, preferably from 60 minutes to 10 seconds before coating. The mixing conditions are not particularly limited as long as the effects of the present invention are sufficiently exhibited. As a specific mixing method, a method of mixing in a tank in which the average residence time calculated from the addition flow rate and the amount of liquid sent to the coater is set to a desired time, by N. Harnby, MFE Edwards, AW Nienow, translated by Koji Takahashi There is a method using a static mixer or the like described in Chapter 8 of "Liquid Mixing Technology" (published by Nikkan Kogyo Shimbun, 1989).

In the present invention, a surfactant may be used for the purpose of improving coating properties and charging. As the surfactant, any surfactant such as nonionic, anionic, cationic, and fluorine can be used as appropriate. Specifically,
No. 62-170950, Fluoropolymer surfactants described in U.S. Pat.No. 5,380,644, JP-A-60-244945, JP-A-63-18
8135 No. fluorinated surfactants described in U.S. Pat.
No. 5,965, and the like, and polysiloxy acid-based surfactants described in JP-A-6-301140 and the like, and polyalkylene oxide and anionic surfactants.

Examples of the solvent used in the present invention include New Solvent Pocket Book (Ohm Co., 1994), but the present invention is not limited thereto. The solvent used in the present invention has a boiling point of 40 ° C or more and 180 ° C or more.
C. or lower is preferred.

Examples of the solvent of the present invention include hexane, cyclohexane, toluene, methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, ethyl acetate, 1,1,1-trichloroethane, tetrahydrofuran,
Triethylamine, thiophene, trifluoroethanol, perfluoropentane, xylene, n-butanol,
Phenol, methyl isobutyl ketone, cyclohexanone, butyl acetate, diethyl carbonate, chlorobenzene, dibutyl ether, anisole, ethylene glycol diethyl ether, N, N-dimethylformamide, morpholine,
Examples include propane sultone, perfluorotributylamine, and water.

The photographic emulsion for heat development in the present invention can be coated on various supports. Typical supports are polyester film, primed polyester film, poly (ethylene terephthalate) film (PET)
Film), polyethylene naphthalate film, cellulose nitrate film, cellulose ester film, poly (vinyl acetal) film, polycarbonate film and related or resinous materials, as well as glass, paper, metal and the like. Coated with a flexible substrate, especially a baryta and / or a partially acetylated α-olefin polymer, especially a polymer of α-olefin having 2 to 10 carbon atoms such as polyethylene, polypropylene, ethylene-butene copolymer. A paper support is typically used. The support may be transparent or opaque, but is preferably transparent.

The recording material of the present invention comprises an antistatic or conductive layer such as a soluble salt (eg, chloride, nitrate, etc.), a vapor-deposited metal layer, US Pat. Nos. 2,861,056 and
It may have a layer containing an ionic polymer as described in US Pat. No. 3,206,312 or an insoluble inorganic salt as described in US Pat. No. 3,428,451.

A method for obtaining a color image using the heat-developable recording material in the present invention is described in JP-A-7-13295, page 10, left column 4
There is a method described from the third line to the 11th left column, 40th line. Also, as a stabilizer for color dye images, UK Patent No. 1,326,889
No. 3,432,300, U.S. Pat.No. 3,698,909, U.S. Pat.
Nos. 574,627, 3,573,050, 3,764,337 and 4,042,394.

The heat-developable recording material of the present invention may be applied by any method. Specifically, extrusion coating, slide coating, curtain coating, dip coating, knife coating,
Various coating operations are used, including flow coating or extrusion coating using a hopper of the type described in U.S. Pat. No. 2,681,294, and are described by Stephen F. Kistl.
er, "LIQUID FILM COATING" by Peter M. Schweizer (C
Extrusion coating or slide coating described on pages 399 to 536, published by HAPMAN & HALL (1997) is preferably used, and particularly preferably slide coating is used. An example of the shape of the slide coater used for slide coating is shown in Figure 11 on page 427 of the same book.
in b.1. Also, if desired, the method described on page 399 to 536 of the same book, U.S. Pat.No. 2,761,791 and British Patent 837,0
Two or more layers can be coated simultaneously by the method described in No. 95.

In the heat-developable recording material of the present invention, additional layers, such as a dye-receiving layer for receiving a moving dye image, an opaque layer if reflective printing is desired, a protective topcoat layer and photothermographic techniques It may include a known primer layer and the like. It is preferable that the recording material of the present invention can form an image with only one material, and it is preferable that a functional layer necessary for image formation such as an image receiving layer does not become another material.

The recording material of the present invention may be developed by any method. Usually, the recording material exposed imagewise is heated and developed. The preferred development temperature is 80 to
The temperature is 250 ° C, more preferably 100 to 140 ° C. The development time is preferably from 1 to 180 seconds, more preferably from 10 to 90 seconds.

The recording material of the present invention may be exposed by any method, but a laser beam is preferred as an exposure light source.
As the laser beam according to the present invention, gas laser, YAG
Lasers, dye lasers, semiconductor lasers and the like are preferred. Further, a semiconductor laser and a second harmonic generation element can be used.

The recording material of the present invention has a low haze upon exposure and tends to cause interference fringes. Examples of the interference fringe prevention technology include a technology for obliquely entering a laser beam into a recording material as disclosed in JP-A-5-113548 and a multi-mode laser disclosed in WO95 / 31754 and the like. There is known a method of utilizing these techniques, and it is preferable to use these techniques.

For exposing the recording material of the present invention, SPIE vo
l.169 Laser Printing 116-128 (1979), JP-A-4-5104
No. 3, WO95 / 31754, etc., it is preferable to expose the laser beams so that they overlap each other so that the scanning lines are not visible.

[0166]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto. Example 1 Application samples Nos. 101 to 125 were prepared as follows, and the effects of the present invention were confirmed. First, a polymer latex used as a binder by adding to the emulsion layer coating solution of the present invention, La1 to L
A method for preparing a11, Lb1 to Lb7, and Lc1 to Lc7 will be described.

(Synthesis of La1) 136 g of styrene was placed in a glass autoclave (TEM-V1000, manufactured by Pressure Glass Co., Ltd.).
280 g of distilled water, 4.44 g of a surfactant (Sandet BL (manufactured by Sanyo Chemical Co., Ltd.)) and 6 g of acrylic acid were added, and the mixture was stirred under a nitrogen stream for 1 hour. Thereafter, the reaction vessel was sealed and 58 g of butadiene was added, and the temperature was raised to 60 ° C. Next, 20 g of an aqueous potassium persulfate solution (5 wt%) was added, and the mixture was stirred for 10 hours. Then, the temperature of the reaction vessel is lowered to room temperature, and the SBR
Latex was obtained. A 1N aqueous ammonia solution was added to the latex to adjust the pH to 8.1. Thus, a latex (La1) having an average particle size of 105 nm and a concentration of 40 wt% was obtained. The equilibrium water content of the polymer at 25 ° C. and 60% RH was 0.6 wt%.

(Synthesis of Lb1) 140 g of styrene was placed in a glass autoclave (TEM-V1000, manufactured by Pressure Glass Co., Ltd.).
280 g of distilled water, 4.44 g of a surfactant (Sandet BL (manufactured by Sanyo Chemical Co., Ltd.)) and 6 g of acrylic acid were added, and the mixture was stirred under a nitrogen stream for 1 hour. Thereafter, 54 g of 2-ethylhexyl acrylate was added, and the temperature was raised to 70 ° C. Next, 20 g of an aqueous solution of ammonium persulfate (5 wt%) was added, and the mixture was stirred for 10 hours. Thereafter, the temperature of the reaction vessel was lowered to room temperature to obtain a styrene-acryl latex. A 1N aqueous ammonia solution was added to the latex to adjust the pH to 7.5. Thus, a latex having an average particle size of 98 nm and a concentration of 42 wt% (Lb
1) was obtained. The equilibrium water content of the polymer at 25 ° C and 60% RH is 0.7
wt%.

(Synthesis of Lc1) 126 g of methyl methacrylate, 280 g of distilled water, and a surfactant (Sandet B) were placed in a glass autoclave (TEM-V1000, manufactured by Pressure Glass Co., Ltd.).
L (manufactured by Sanyo Kasei Co., Ltd.)) and acrylic acid (4 g) were added, and the mixture was stirred under a nitrogen stream for 1 hour. Thereafter, 70 g of ethyl acrylate was added, and the temperature was raised to 60 ° C. Next, 20 g of an aqueous potassium persulfate solution (5 wt%) was added, and the mixture was stirred for 10 hours. Thereafter, the temperature of the reaction vessel was lowered to room temperature to obtain an acrylic latex. A 1N aqueous ammonia solution was added to the latex to adjust the pH to 7.5. Thus, a latex (Lc1) having an average particle size of 101 nm and a concentration of 44 wt% was obtained.
The equilibrium water content of the polymer at 25 ° C. and 60% RH was 0.7% by weight.

(Synthesis of La2-La11, Lb2-Lb7, Lc2-Lc7) These latexes were prepared first. La1, Lb1, Lc
In the preparation method 1, part or all of the aqueous ammonia solution for pH adjustment was replaced with potassium hydroxide, or these latexes were prepared by using a combination of ultrafiltration (UF) purification methods described below. . The average particle diameter and the equilibrium water content are the same as those of La1, Lb1, and Lc1, respectively.

(UF Purification Method) A polymer latex appropriately diluted with distilled water was used to prepare a UF-purification module, FSO3
It was diluted and purified using -FC-FUY03A1 (Daisen Membrane System Co., Ltd.) until it reached the desired cation concentration. The measurement of the cation concentration was performed using the following apparatus and conditions.

(Measurement of Cation Concentration) Measuring device: Ion Chromato 8000 series (Detector is CM-80
Separation column: TSK Gel IC-Cation (without guard column) Eluent: 2 mM-HNO ₃ Flow rate: 1.2 ml / min Standard solution: Cation mixed standard solution I for chromatography
(Manufactured by Kanto Chemical Co., Ltd.) The cation concentrations of the prepared latex are summarized in Table 1.

<< Preparation of PET Support >> Intrinsic viscosity IV = 0.66 (measured at 25 ° C. in phenol / tetrachloroethane = 6/4 (weight ratio)) using terephthalic acid and ethylene glycol according to a conventional method. Got PET. This was pelletized, dried at 130 ° C. for 4 hours, melted at 300 ° C., extruded from a T-die, and rapidly cooled to prepare an unstretched film having a thickness of 175 μm after heat fixing.

This was longitudinally stretched 3.3 times using rolls having different peripheral speeds, and then transversely stretched 4.5 times using a tenter. The temperatures at this time were 110 ° C. and 130 ° C., respectively.
After that, it was heat-set at 240 ° C. for 20 seconds and relaxed 4% in the lateral direction at the same temperature. Then, after slitting the chuck portion of the tenter, knurling was performed on both ends and wound at 4 kg / cm ² to obtain a roll having a thickness of 175 μm.

<< Surface Corona Treatment >> Using a solid state corona treatment machine 6KVA model manufactured by Pillar Co., both surfaces of the support were treated at room temperature at 20 m / min. From the current and voltage readings at this time, it was found that the support was treated at 0.375 kV · A · min / m ² . At this time, the processing frequency was 9.6 kHz, and the gap clearance between the electrode and the dielectric roll was 1.6 mm.

<< Preparation of Undercoating Support >> (Preparation of Undercoating Coating Solution A) Polystyrene fine particles (average particle size: 0.2 μm) were added to 200 ml of a polyester copolymer aqueous dispersion Pesresin A-515GB (30 wt%, manufactured by Takamatsu Oil & Fats Co., Ltd.). ) 1g, surfactant
20 ml of 1 (1 wt%) was added, and distilled water was added thereto to make 1000 ml, thereby obtaining an undercoat coating liquid A.

(Preparation of Undercoating Coating Solution B) 200 ml of an aqueous dispersion of a styrene-butadiene copolymer (styrene / butadiene / itaconic acid = 47/50/3 (weight ratio), concentration of 30 wt%) in 680 ml of distilled water,
Add 0.1 g of polystyrene fine particles (average particle size 2.5 μm),
Further, distilled water was added to make 1000 ml to obtain an undercoating coating solution B.

(Preparation of Undercoating Coating Solution C) Inert Gelatin 1
0 g was dissolved in 500 ml of distilled water, and 40 g of an aqueous dispersion (40 wt%) of tin oxide-antimony oxide composite fine particles described in JP-A-61-20033 was added thereto, and distilled water was added thereto. Ten
Undercoating solution C was made up to 00 ml.

(Preparation of Undercoating Support) After the above-mentioned corona discharge treatment, the undercoating coating solution A was applied with a bar coater so that the wet coating amount was 5 ml / m ² , and dried at 180 ° C. for 5 minutes. The dry film thickness was about 0.3 μm. Then this back
After applying the corona discharge treatment to the (back side), the undercoat coating liquid
B is applied with a bar coater so that the wet coating amount is 5 ml / m ² , and the dried film thickness is about 0.3 μm, dried at 180 ° C. for 5 minutes, and further, an undercoat coating liquid C is wet-coated with a bar coater. An undercoating support was prepared by applying the solution in an amount of 3 ml / m ² and a dry film thickness of about 0.03 μm and drying at 180 ° C. for 5 minutes.

<< Preparation of Organic Acid Silver Dispersion >> 43.8 g of behenic acid (product name: Edenor C22-85R) manufactured by Henkel, 730 ml of distilled water,
While stirring tert-butanol (60 ml) at 79 ° C., 1N-NaOH aqueous solution (117 ml) was added over 55 minutes and reacted for 240 minutes. Then
112.5 ml of an aqueous solution of 19.2 g of silver nitrate was added over 45 seconds, left as it was for 20 minutes, and cooled to 30 ° C. Thereafter, the solid content was separated by suction filtration, and the solid content of the filtrate had a conductivity of 30 μS / cm.
And washed with water. The solid content thus obtained is handled as a wet cake without drying, and
To 100 g of the wet cake, 7.4 g of polyvinyl alcohol (trade name: PVA-205) and water were added to make the total amount 385 g, and the mixture was predispersed with a homomixer.

Next, the pre-dispersed stock solution is dispersed in a disperser (trade name: Microfluidizer M-110S-EH, manufactured by Microfluidics International Corporation, using G10Z interaction chamber).
The pressure was adjusted to 1750 kg / cm ² and the mixture was treated three times to obtain a silver behenate dispersion B. The silver behenate particles contained in the silver behenate dispersion thus obtained were needle-like particles having an average minor axis of 0.04 μm, an average major axis of 0.8 μm, and a variation coefficient of 30%. For particle size measurement, use MasterSizerX manufactured by Malvern Instruments Ltd.
I went in. In the cooling operation, a coiled heat exchanger was mounted before and after the interaction chamber, and the temperature of the refrigerant was adjusted to a desired dispersion temperature.

<< Preparation of 25 wt% Dispersion of Reducing Agent >> 1,1-bis
(2-Hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane 80 g and Kuraray Co., Ltd. did. 800 g of zirconia beads having an average diameter of 0.5 mm were prepared, put into a vessel together with the slurry, and dispersed with a dispersing machine (1 / 4G sand grinder mill: manufactured by IMEX Co., Ltd.) for 5 hours to obtain a reducing agent dispersion.
The reducing agent particles contained in the reducing agent dispersion thus obtained had an average particle size of 0.72 μm.

<< Preparation of 20 wt% Dispersion of Mercapto Compound >> 32 g of a 20 wt% aqueous solution of 3-mercapto-4-phenyl-5-heptyl-1,2,4-triazole 64 g and modified polyvinyl alcohol poval MP203 manufactured by Kuraray Co., Ltd. 224 g of water was added thereto and mixed well to form a slurry. 800 g of zirconia beads having an average diameter of 0.5 mm were prepared, placed in a vessel together with the slurry, and dispersed with a disperser (1 / 4G sand grinder mill: manufactured by IMEX Co., Ltd.) for 10 hours to obtain a mercapto dispersion. The mercapto compound particles contained in the thus obtained dispersion of the mercapto compound had an average particle size of 0.67 μm.

<< Preparation of 30 wt% dispersion of organic polyhalogen compound >> 48 g of tribromomethylphenylsulfone and 3-tribromomethylsulfonyl-4-phenyl-5-tridecyl-
224 g of water was added to 48 g of 1,2,4-triazole and 48 g of a 20 wt% aqueous solution of modified polyvinyl alcohol poval MP203 manufactured by Kuraray Co., Ltd., and mixed well to form a slurry. 800 g of zirconia beads having an average diameter of 0.5 mm are prepared, put into a vessel together with the slurry, and dispersed with a dispersing machine (1 / 4G sand grinder mill: manufactured by IMEX Co., Ltd.) for 5 hours to obtain an organic polyhalogen compound dispersion. Was. The polyhalogen compound particles contained in the polyhalogen compound dispersion thus obtained had an average particle size of 0.74 μm.

<< Preparation of methanol solution of phthalazine compound >> A solution of 26 g of 6-isopropylphthalazine in 100 ml of methanol was used.

<< Preparation of 20 wt% Dispersion of Pigment >> CI Pigmen
t 64 g of Blue 60 and 6.4 g of Demol N manufactured by Kao Corporation, 250 g of water
Was added and mixed well to obtain a slurry. Average diameter 0.5mm
Of zirconia beads was placed in a vessel together with the slurry, and dispersed by a dispersing machine (1 / 4G sand grinder mill: manufactured by Imex Co., Ltd.) for 25 hours to obtain a pigment dispersion. The pigment particles contained in the pigment dispersion thus obtained had an average particle size of 0.21 μm.

<< Preparation of Silver Halide Grain 1 >> Distilled water 1421c
Add 1wt% potassium bromide solution 6.7cc to c and add 1N nitric acid
While stirring the liquid containing 8.2 cc and 21.8 g of phthalated gelatin in a titanium-coated stainless steel reaction vessel, the liquid temperature was maintained at 35 ° C, and a solution obtained by adding distilled water to 37.04 g of silver nitrate to 159 cc and diluting the solution a1 with odor was added. A solution b1 in which 32.6 g of potassium iodide was diluted to a volume of 200 cc with distilled water was prepared, and the entire amount of the solution a1 was added over 1 minute at a constant flow rate while maintaining the pAg at 8.1 by the control double jet method (solution b1). Is added by the controlled double jet method). Thereafter, 30 cc of a 3.5 wt% aqueous hydrogen peroxide solution was added, and 3 wt% of benzimidazole was further added.
33.6 cc of the aqueous solution was added. Then, the solution a1 was again diluted with distilled water to 317.5 cc, and the solution b1 was dissolved with dipotassium hexachloride iridium acid so that the final concentration was 1 × 10 ^-4 mol per mol of silver with respect to the solution b1. Using a solution b2 diluted with distilled water to 400 cc twice the amount of the solution b1, again by the controlled double jet method, while maintaining the pAg at 8.1, the entire amount of the solution a2 was added at a constant flow rate over 10 minutes. (Solution b2
Is added by the controlled double jet method). afterwards
Add 50 cc of a 0.5 wt% methanol solution of 2-mercapto-5-methylbenzimidazole, further raise the pAg to 7.5 with silver nitrate, adjust the pH to 3.8 with 1N sulfuric acid, stop stirring, settle / desalinate / Perform a water washing process, 3.5 g of deionized gelatin
And 1N sodium hydroxide, pH 6.0, pAg
Adjusting to 8.2 produced a silver halide dispersion.

The grains in the completed silver halide emulsion are pure silver bromide grains having an average sphere equivalent diameter of 0.031 μm and a variation coefficient of the equivalent sphere diameter of 11%. The particle size and the like were determined from the average of 1000 particles using an electron microscope. The {100} plane ratio of these particles was determined to be 85% using the Kubelka-Munk method.

The emulsion was heated to 50 ° C. while stirring, and N,
5 ml of a 0.5 wt% methanol solution of N'-dihydroxy-N '', N ''-diethylmelamine and 5 cc of a 3.5 wt% methanol solution of phenoxyethanol were added, and after 1 minute, sodium benzenethiosulfonate was added to 1 mol of silver. 3 × 10 ^-5 mol was added. After 2 minutes, a solid dispersion of the spectral sensitizing dye 1 (aqueous gelatin solution)
Was added at 5 × 10 ⁻³ mol per mol of silver, and after 2 minutes, the tellurium compound was added at 5 × 10 ⁻⁵ mol per mol of silver, followed by aging for 50 minutes. Immediately before the completion of the ripening, the temperature was lowered by adding 1 × 10 ⁻³ mol of 2-mercapto-5-methylbenzimidazole per 1 mol of silver, and the chemical sensitization was terminated to prepare silver halide grains 1.

<< Preparation of silver halide grains 2 >> After dissolving 22 g of phthalated gelatin and 30 mg of potassium bromide in 700 ml of water, adjusting the pH to 5.0 at a temperature of 35 ° C., containing 18.6 g of silver nitrate and 0.9 g of ammonium nitrate An aqueous solution containing 159 ml of an aqueous solution and a 92: 8 molar ratio of potassium bromide and potassium iodide was pA
While maintaining the g at 7.7, it was added over 10 minutes by the control double jet method. Then, 1 ml in 476 ml and 1 liter of an aqueous solution containing 55.4 g of silver nitrate and 2 g of ammonium nitrate
An aqueous solution containing × 10 ⁻⁵ mol of dipotassium hexachloride iridate and 1 mol of potassium bromide was added over 30 minutes by a control double jet method while maintaining the pAg at 7.7.
Hydroxy-6-methyl-1,3,3a, 7-tetrazaindene (1 g) was added, and the pH was further lowered to cause coagulation and sedimentation for desalination. After that, 0.1 g of phenoxyethanol was added, and pH 5.
9, adjusted to pAg8.2 silver iodobromide grains (iodine content core 8 mol%,
Average 2 mol%, average size 0.05 μm, projection area variation coefficient 8
%, Cubic particles having a {100} face ratio of 88%).

The silver halide grains thus obtained were heated to 60 ° C., and 85 μmol of sodium thiosulfate and 2,2
1.1 × 10 ⁻⁵ mol of 3,4,5,6-pentafluorophenyldiphenylphosphine selenide, 1.5 × 10 ⁻⁵ mol of tellurium compound, 3.5 × 10 ⁻⁸ mol of chloroauric acid, 2.7 × 10 ^{− Four}
After aging for 120 minutes, the mixture was rapidly cooled to 40 ° C., and 1 × 10 ^-4 mol of spectral sensitizing dye 1 and 5 × 10 ^-4 mol of 2-mercapto-5-methylbenzimidazole were added. The mixture was rapidly cooled to ° C. to obtain a silver halide emulsion 2.

<< Preparation of Emulsion Layer Coating Solution >> (Emulsion Layer Coating Solution No. 1) 103 g of the organic acid silver dispersion obtained above and 5 g of a 20 wt% aqueous solution of polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.) were mixed. While keeping at 40 ° C., 23.2 g of the above 25 wt% reducing agent dispersion, 1.2 g of a 20 wt% aqueous dispersion of the pigment CI Pigment Blue 60, 10.7 g of an organic polyhalogen compound 30 wt% dispersion, and 20 wt% dispersion of a mercapto compound 3.1 g of the product were added.

Thereafter, the polymer latex La1 kept at 40 ° C. was added in an adjusted amount so that the latex solid content became 42.4 g, and after sufficient stirring, 6 ml of a methanol solution of a phthalazine compound was added, and the organic acid silver salt was added. A contained liquid was obtained. Also, 5 g of silver halide grains 1 and 5 g of silver halide grains 2
The mixture was mixed well in advance and mixed with a liquid containing an organic acid silver by a static mixer just before coating to prepare a coating solution for an emulsion layer, and the solution was directly sent to a coating die at a coating amount of 1.4 g / m ² .

The viscosity of the above emulsion layer coating solution was measured with a B-type viscometer of Tokyo Keiki Co., Ltd., and was found to be 85 mPa · s at 40 ° C. (No. 1 rotor).
s]. The viscosity of the coating solution at 25 ° C. using an RFS Fluid Spectrometer manufactured by Rheometrics Far East Co., Ltd. was determined at a shear rate of 0.1, 1, 10, 100, 1000 [1 /
Sec] were 1500, 220, 70, 40, and 20 [mPa · s], respectively.

<< Preparation of Emulsion Surface Intermediate Layer Coating Solution >> (Intermediate Layer Coating Solution) Polyvinyl alcohol PVA-205 (Kuraray)
772 g of a 10 wt% aqueous solution of methyl methacrylate / styrene / 2-ethylhexyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization weight ratio 59
/ 9/26/5/1) Aerosol OT in 27.5wt% latex liquid 226g
2 ml of a 5 wt% aqueous solution (manufactured by American Cyanamid Co., Ltd.), 4 g of benzyl alcohol, 1 g of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate and 10 mg of benzoisothiazolinone were added to the intermediate layer. The solution was fed to a coating die at 5 ml / m ² . The viscosity of the coating solution was 21 mPa · s at 40 ° C. (No. 1 rotor) using a B-type viscometer.

<< Preparation of Emulsion Surface Protective Layer First Layer Coating Solution >> (Protective Layer First Layer Coating Solution) 80 g of inert gelatin was dissolved in water, 138 ml of a 10 wt% methanol solution of phthalic acid, 28 ml of 1N sulfuric acid were added. Aerosol OT (American Cyanamid)
5 ml of a 5 wt% aqueous solution of phenoxyethanol 1 g was added,
Water was added so as to make the total amount 1000 g, thereby forming a coating solution for the first layer of the protective layer. The solution was fed to a coating die so as to have a concentration of 10 ml / m ² . The viscosity of the coating solution was measured using a B-type viscometer at 40 ° C (No. 1 rotor).
It was 17 [mPa · s].

<< Preparation of Coating Solution for Emulsion Surface Protective Layer Second Layer >> (Protective Layer Second Layer Coating Solution) Inert gelatin (100 g) was dissolved in water, and N-perfluorooctylsulfonyl-N-propylalanine potassium salt was 5 wt%. 20 ml of solution, aerosol
16 ml of a 5 wt% solution of OT (manufactured by American Cyanamid Co.), polymethyl methacrylate fine particles (average particle size 4.0 μm) 25
g, 44 ml of 1N sulfuric acid, 10 mg of benzoisothiazolinone and water to a total amount of 1555 g, and 445 ml of an aqueous solution containing 4 wt% chromium alum and 0.67 wt% phthalic acid were applied with a static mixer immediately before application. The mixture was used as a coating liquid for the second layer of the protective layer, and was fed to a coating die so as to have a concentration of 10 ml / m ² . The viscosity of the coating solution was 9 [mPa · s] with a B-type viscometer at 40 ° C. (No. 1 rotor).

<< Preparation of Back Surface Coating Solution >> (Preparation of Solid Precursor Dispersion of Base Precursor) 64 g of the base precursor compound and 10 g of a surfactant Demol N manufactured by Kao Corporation were mixed with 246 ml of distilled water. Beads are dispersed using a sand mill (1/4 Gallon sand grinder mill, manufactured by AIMEX Co., Ltd.), and the average particle diameter is 0.2 μm.
The solid precursor dispersion liquid of the base precursor was obtained.

(Preparation of Dye Solid Fine Particle Dispersion) 9.6 g of a cyanine dye compound and 5.8 g of sodium p-alkylbenzenesulfonate were mixed with 305 ml of distilled water, and the mixture was subjected to a sand mill (1/4 Gallon sand grinder mill, Amimex Co., Ltd.). )) To disperse the beads to obtain an average particle diameter of 0.
A dye solid fine particle dispersion of 2 μm was obtained.

(Preparation of Anti-Halation Layer Coating Solution) Gelatin 17 g, polyacrylamide 9.6 g, solid fine particle dispersion of the above base precursor 70 g, solid fine particle dispersion of the above dye 56 g, polymethyl methacrylate fine particles (average particle size 6.5 μm) 1.5 g, 2.2 g of sodium polyethylene sulfonate, 0.2 g of a 1% by weight aqueous solution of a coloring dye compound, 844 g of H ₂ O
The mixture was mixed to prepare an antihalation layer coating solution.

(Preparation of Coating Solution for Protective Layer) The container was kept warm at 40 ° C., and 50 g of gelatin and sodium polystyrene sulfonate were prepared.
0.2 g, N, N'-ethylenebis (vinylsulfoneacetamide) 2.4 g, t-octylphenoxyethoxyethaneethanesulfonate 1 g, benzoisothiazolinone 30 mg,
32 mg of C ₈ F ₁₇ SO ₃ K, C ₈ F ₁₇ SO ₂ N (C ₃ H ₇ ) (CH ₂ CH ₂ O) ₄ (CH ₂ ) ₄ -S
64 mg of O ₃ Na and 950 ml of H ₂ O were mixed to prepare a coating solution for a protective layer.

[0202]

Embedded image

<< Preparation of Photothermographic Material >> Emulsion Layer Coating Solution N
Using o.1, coating sample No. 101 was prepared by the following method.

The coating solution for the antihalation layer was applied to the undercoated support at a solid content of the solid fine particle dye of 0.04 g /
m ^2, and the protective layer coating solution was simultaneously coated as the coating amount of gelatin of 1 g / m ^2, dried and after creating the antihalation back layer, the emulsion layer from the undercoat surface opposite to the surface and back face, The intermediate layer, the protective layer first layer, and the protective layer second layer were simultaneously coated in multiple layers by a slide bead coating method to prepare a photothermographic material sample. The emulsion surface was applied without winding after coating the back surface.

The coating was performed at a speed of 160 m / min, the distance between the tip of the coating die and the support was set to 0.18 mm, and the pressure in the decompression chamber was set 392 Pa lower than the atmospheric pressure. In the subsequent chilling zone, air with a dry-bulb temperature of 18 ° C and a wet-bulb temperature of 12 ° C is blown at an average wind speed of 7 m / s for 30 seconds to cool the coating liquid, and then a wrap-around floating type drying zone A dry air having a dry-bulb temperature of 30 ° C. and a wet-bulb temperature of 18 ° C. was blown out from the holes at an air velocity of 20 m / sec for 200 seconds to volatilize the solvent in the coating solution.

Next, coating samples No. 102 to 125 were prepared by changing the polymer latex to be added to the emulsion layer coating solution to La2 to La11, Lb1 to Lb7, and Lc1 to Lc7. The prepared coating samples are shown together with the results in Table 1. The following evaluation was performed about each sample. Table 1 shows the results.

(Evaluation of Maximum Density Ratio) After exposing the coated sample with a laser sensitometer equipped with a 660 nm diode, the sample was developed at 122 ° C. for 19 seconds, and the obtained image density was measured with a densitometer. The highest concentration value was determined, and the highest concentration ratio was calculated by the following formula. As the value of the maximum density ratio is larger, a relatively high image density is obtained, which is evaluated as preferable. Maximum concentration ratio: (Maximum concentration in each sample) ÷ (Sample No. 1
01 highest concentration)

(Evaluation of minimum density ratio)
After developing at 122 ° C. for 19 seconds, the obtained image density was measured with a densitometer to determine the minimum density value, and the minimum density ratio was calculated by the following formula. As the value of the minimum density ratio is smaller, an image density with a relatively low noise level is obtained, which is evaluated as preferable. Minimum concentration ratio: (minimum concentration in each sample) ÷ (minimum concentration in sample No. 101) A sample having a large maximum concentration ratio and a small minimum concentration ratio is preferable for a sample having a high S / N.

(Evaluation of Silver Tone of Developed Sample) The coated sample was exposed through a step wedge, developed at 122 ° C. for 19 seconds, and the obtained developed sample was observed through white light. In the evaluation, the degree of deviation from the black color tone, which is considered to be practically preferable, was sensory evaluated according to the following evaluation criteria. ◎ 、 ○ 、 △
Is a practically acceptable level. A: Recognized as black and preferable. ○: slight change in color tone from black, but not bothersome. Δ: tends to be brown, yellow or red depending on the exposure amount. C: Brown, yellow, and red tend to be exhibited at any exposure amount, which is not preferable. XX: The deviation from black is remarkable and not practical.

[0210]

[Table 1]

From the results of Sample Nos. 105 to 111, 116 to 118, and 123 to 125, the photothermographic material of the present invention has a high S / N and a good silver tone of the developed sample, and can be provided for practical use. Is obtained. On the other hand, sample Nos. 101-104, 112-
It can be seen that in the case of 115, 119 to 122, a practical photothermographic material cannot be obtained because the two characteristics of S / N and silver tone are incompatible.

[0212]

According to the present invention, a heat-developable recording material having a high S / N and a good silver tone can be coated with a water solvent without using an organic solvent which is harmful to the environment and the human body and which is disadvantageous in cost. It can be seen that it can be manufactured.

[Procedure amendment]

[Submission date] October 22, 1998 (1998.10.
22)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 1

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

[0011]

The above object has been achieved by the present invention described below. (1) In a heat-developable recording material having at least an organic silver salt, a reducing agent, and a binder on a support, ammonium ion, sodium ion, and potassium ion are contained in an amount of 50% by weight or more of the total binder in the organic silver salt-containing layer. And a polymer latex containing 600 ppm or less in total. (2) The heat-developable recording material according to (1), wherein the total of sodium ions and potassium ions contained in the polymer latex is 200 ppm or less. (3) The heat-developable recording material according to the above (2), wherein the polymer latex contains 200 ppm or less of ammonium ions. (4) The above (1) to (3) containing a photosensitive silver salt
Any one of the heat-developable recording materials. (5) 25% 60% of the polymer of the polymer latex
The heat-developable recording material according to any one of (1) to (4), wherein the equilibrium water content at RH is 2% by weight or less. (6) The heat-developable recording material according to any one of the above (1) to (5), wherein the organic silver salt is an organic carboxylic acid silver salt.

[Procedure amendment 3]

[Document name to be amended] Abstract

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Abstract

【wrap up】

PROBLEM TO BE SOLVED: To provide a heat-developable recording material which has a good silver tone and gives a high S / N image.

SOLUTION: In a heat-developable recording material having at least an organic silver salt, a reducing agent, and a binder on a support, 50% by weight of the total binder in the layer containing the organic silver salt is used.
As described above, a heat-developable recording material using a polymer latex containing a total of 600 ppm or less of ammonium ion, sodium ion and potassium ion.

[Selection diagram] None

Claims (6)

[Claims] 1. A photothermographic material having at least an organic silver salt, a reducing agent, and a binder on a support, wherein at least 50% by weight of the total binder of the organic silver salt-containing layer is ammonium ion, sodium ion, and A heat-developable recording material using a polymer latex containing potassium ions in a total amount of 600 ppm or less. 2. The heat-developable recording material according to claim 1, wherein the total of sodium ions and potassium ions contained in the polymer latex is 200 ppm or less. 3. The heat-developable recording material according to claim 2, wherein ammonium ion contained in the polymer latex is 200 ppm or less. 4. The method according to claim 1, which comprises a photosensitive silver salt.
Any one of the heat-developable recording materials. 5. The polymer of the polymer latex at 25 ° C.
5. The heat-developable recording material according to claim 1, wherein an equilibrium water content at 60% RH is 2% by weight or less. 6. The heat-developable recording material according to claim 1, wherein the organic silver salt is an organic silver carboxylate.