JP2002023305A - Heat developable material having improved preservable property at high temperature - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat developable material which ensures low fog and high density although it is used in an aqueous coating system, gives a high quality image having desirable contrast and has low fog even in preservation at high temperature. SOLUTION: In the heat developable material having a photosensitive layer containing photosensitive silver halide grains on at least one face of the base, an organic silver salt and a reducing agent blocked by a group containing a nitrogen-containing aromatic group are contained in the photosensitive layer or at least one non-photosensitive layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-developable material for forming an image by heat development, and more particularly, to a low fog, a high density and a high contrast despite the water-based coating method. The present invention relates to a heat-developable material which can provide a high quality image and has low fog even when stored under high temperature.

[0002]

2. Description of the Related Art In recent years, in the fields of medical treatment and printing, waste liquid due to wet processing of image forming materials has become a problem in terms of workability. Weight loss is strongly desired. Therefore, there is a need for a technique relating to a photothermographic material for photographic technology that can form a high-resolution and clear black image by thermal development. As this technique, for example, US Pat.
No. 2,904, 3,487,075 and D.C. "Dry Silver Photographic" by Morgan
Materials) "(Handbook of I
Managing Materials, Marcel D
ekker, Inc. 48, 1991) are well known. These photosensitive materials are usually 8
Since the development is performed at a temperature of 0 ° C. or higher, it is called a heat development material.

By the way, most of the heat developing materials of this type have conventionally been manufactured by applying a solvent. The reason for this is that the photosensitive layer, which is coated by mixing a developer and an organic silver salt, has a drawback that the oxidation-reduction reaction proceeds through water and fog increases. For this purpose, a method has been considered in which a fogging inhibitor that makes fogging less likely to be caused by heat is searched for, and a block type developer that temporarily blocks the activity of the developer is used. For example,
JP-A-60-184879, JP-A-60-210
No. 491, JP-A-63-137888, JP-A-4-117351, JP-A-4-144787 and the like disclose a urethane-type block obtained by reacting a phenol compound with an isocyanate compound. Was to utilize an agent. At room temperature, these urethane-type blocked developers are inactive because hydroxyl groups are chemically blocked and can be stably present in water, and the stability of the liquid at the time of coating, that is, the stagnation property is good. When heated during development, it is decomposed into an original developer and an isocyanate compound to reduce organic silver salts such as behenic acid and arachidic acid. Therefore, a photosensitive material using this type of developer does not cause fog unless the decomposition temperature is reached, and does not cause unnecessary fog due to heat, humidity, or the like. Attempts have been made to apply reduction of organic silver salts with this reducing compound, but there was a drawback that the development temperature was high.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a low-fogging, high-density, high-contrast, high-quality image and a high-temperature image in spite of using an aqueous coating method. An object of the present invention is to provide a heat-developable material having low fog even when stored.

[0005]

The above object is achieved by the following.

[0006] 1. In a heat-developable material having a photosensitive layer containing photosensitive silver halide grains on at least one surface of the support, at least one of the photosensitive layer and the non-photosensitive layer,
A heat-developable material containing an organic silver salt and a reducing agent blocked with a group containing a nitrogen-containing aromatic group.

[0007] 2. In a heat-developable material having a photosensitive layer containing photosensitive silver halide grains on at least one surface of the support, at least one of the photosensitive layer and the non-photosensitive layer,
A heat-developable material comprising an organic silver salt, a reducing agent blocked with a group containing a nitrogen-containing aromatic group, and a mechanism for promoting the imagewise release of the reducing agent by heat.

[0008] 3. 3. The heat-developable material according to 1 or 2, wherein the reducing agent blocked with a group containing a nitrogen-containing aromatic group is represented by the general formula (1).

4. 4. The photothermographic material according to any one of items 1 to 3, wherein the hydrophobic latex in the layer containing the organic silver salt has a mass ratio of 1/5 to 10 times the amount of silver.

[0010] 5. 5. The photothermographic material according to any one of items 1 to 4, wherein a pH adjusting agent is contained in a layer adjacent to the photosensitive layer, and the pH in the film of the photosensitive layer is maintained at 2 or more and 5 or less.

Hereinafter, the present invention will be described in detail. Since the heat-developable material contains an organic silver salt and a reducing agent in the photosensitive layer containing silver halide particles, the reducing agent gradually reduces the silver halide and the organic silver salt during storage. Causes fog, and lowers sensitivity and softness. This reaction is promoted by the temperature, and at a high temperature, fog is more liable to occur, sensitivity is reduced, and softness is liable to occur, resulting in deterioration of image quality. Therefore, it is considered that if the reduction reaction can be suppressed in a normal state, this reaction can be suppressed. However, if the suppression is applied, the development activity will be reduced. Therefore, by using a precursor compound which releases the reducing agent in a timely manner by the heat of development, the preservability of the heat-developable material can be improved. . As the precursor compound from which the reducing compound is released by heat, a reducing agent blocked with a group containing a nitrogen-containing aromatic group is preferable, and a compound represented by the general formula (1) can be mentioned as a preferable example.

The compound represented by formula (1) will be described in detail. In the general formula (1), Ar represents an aryl group. Examples of the aryl group include a phenyl group, a bisphenyl group, a naphthyl group, and a bisnaphthyl group which may be substituted with a substituent such as an electron withdrawing group or an electron donating group. It represents an aromatic group or an aryl group such as a ring or a condensed ring containing a hetero atom. The electron withdrawing group and the electron donating group of the substituent of the aryl group represented by Ar can be appropriately selected. For example, an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, cyclopentyl group, hexyl group, cyclohexyl group, etc.), an alkenyl group (for example, vinyl group, allyl group, etc.) An alkynyl group (eg, propargyl group), an aryl group (eg, phenyl group), a heterocyclic group (eg, pyridyl group,
Thiazolyl group, oxazolyl group, imidazolyl group, furyl group, pyrrolyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, selenazolyl group, sulfolanyl group, piperidinyl group, pyrazolyl group, tetrazolyl group, etc., halogen atom (for example, chlorine atom, bromine Atom, iodine atom,
A fluorine atom), an alkoxy group (for example, a methoxy group,
Ethoxy group, propyloxy group, pentyloxy group, cyclopentyloxy group, hexyloxy group, cyclohexyloxy group, etc., aryloxy group (eg, phenoxy group, etc.), alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyloxycarbonyl Group, butyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, etc.), sulfonamide group (eg, methylsulfonylamino group, ethylsulfonylamino group, butylsulfonylamino group, hexylsulfonylamino group, cyclohexyl) Sulfonylamino group, phenylsulfonylamino group, etc., sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group) Hexyl aminosulfonyl group, cyclohexylaminosulfonyl group, phenyl aminosulfonyl group, 2-pyridyl aminosulfonyl group), a ureido group (e.g., methylureido group, an ethylureido group,
Pentylureido group, cyclohexylureido group, phenylureido group, 2-pyridylureido group, etc., acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, phenylcarbonyl group, pyridylcarbonyl) Carbamoyl group (eg, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.) Amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, phenylcarbonylamino ), A sulfonyl group (eg, a methylsulfonyl group, an ethylsulfonyl group, a butylsulfonyl group, a cyclohexylsulfonyl group, a phenylsulfonyl group, a 2-pyridylsulfonyl group, etc.), an amino group (eg, an amino group, an ethylamino group, a dimethylamino group) Group,
Butylamino group, cyclopentylamino group, anilino group, 2-pyridylamino group, etc.), cyano group, nitro group,
It can be selected from a sulfo group, a carboxyl group, a hydroxyl group, an oxamoyl group and the like.

[0013] X represents an oxygen atom or a sulfur atom or an amino group, an amino group -N (R ₁₎ - (wherein, R ₁ represents a hydrogen atom or a substituent) is represented by, R ₁ is hydrogen Atomic ones are preferred.

R represents a group containing a nitrogen-containing aromatic group,
Examples of the nitrogen-containing aromatic group, for example, pyridyl group, pyrimidinyl group, pyridazinyl group, pyrazinyl group, triazinyl group, quinolinyl group, phthalazinyl group, pyrrolyl group, imidazolyl group, pyrazolyl group, triazolyl group, tetrazolyl group, oxazolyl group, isoxazolyl group Benzoisoxazolyl group, thiazolyl group, benzothiazolyl group, oxadiazolyl group, thiadiazolyl group and the like, and these groups may be substituted with various substituents. The group containing a nitrogen-containing aromatic group represented by R is not particularly limited as long as it is a group containing the above-described nitrogen-containing aromatic group.

The reducing agent blocked by a group containing a nitrogen-containing aromatic group, which is a compound represented by the general formula (1) used in the present invention, comprises a reaction between a phenol compound and an acid halide,
It can be synthesized by a synthesis method such as a reaction between a phenol compound and an oxalyl halide, a reaction between a phenol compound and an isocyanate, and a reaction between a phenol compound and chloroformate.

Examples of the phenol compound blocked by the group containing a nitrogen-containing aromatic group include phenol, p-methoxyphenol, p-nitrophenol,
p-chlorophenol, p-bromophenol, 3,4
-Dichlorophenol, p-tert-butylphenol, p-phenylphenol, 3-diethylaminophenol, 1-naphthol, 2-naphthol, methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate,
butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, 4-hydroxy-4'-isopropyloxydiphenylsulfone, 4-methyl-4'-hydroxydiphenylsulfone, 4-hydroxy-4'-chlorodiphenylsulfone, salicylic acid, Ethyl salicylate, catechol, resorcinol, tert-butylcatechol, bis (4-hydroxyphenyl) sulfone, 4-methyl-3 ', 4'-dihydroxydiphenylsulfone,
3,3'-diallyl-4,4'-dihydroxydiphenylsulfone, 2,2-bis (p-hydroxyphenyl)
Propane, methyl bis (4-hydroxyphenyl) acetate, pyrogallol, phloroglucinol, gallic acid, methyl gallate, ethyl gallate, n-propyl gallate, butyl gallate, lauryl gallate, stearyl gallate and the like. .

In the case of a heat-developable material using a blocked developer, the temperature at which development starts depends on the dissociation temperature of the blocking group of the blocked developer.
It is an important factor in terms of the sensitivity of the heat developing material. Therefore, also in the blocked developer used in the heat developing material of the present invention, it is desirable that the dissociation temperature is as low as possible,
Even if it is high, those having a dissociation temperature of 160 ° C. or less are preferred.

Specific examples of the compound represented by the general formula (1) are shown below.

[0019]

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[0020]

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[0021]

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[0022]

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[0023]

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[0024]

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In the compound of the present invention in which the aromatic hydroxyl group represented by the general formula (1) is blocked, at least one of the substituents adjacent to the hydroxyl group is an alkyl group having 1 to 35 carbon atoms which may be substituted. It is preferably substituted. In particular, when a substituent is introduced at a position adjacent to a hydroxyl group, thermal elimination is promoted.
It is preferred to introduce a substituent. The substituents are preferably arranged on both sides adjacent to the hydroxyl group, but may be separated.

Examples of the substituent include a methyl group, an ethyl group,
Propyl group, iso-propyl group, tert-butyl group, tert-amyl group, adamantyl group, 1-methyladamantan-1-yl, 4-methylcyclohexanone-4-yl, lactone group, 1-methyllactone-1-yl And the like.

The method for synthesizing the compound represented by the general formula (1) of the present invention is described below. Compound (3) can be synthesized by the following synthesis route.

[0028]

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Compound (16) can be synthesized by the following synthetic route.

[0030]

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Compound (18) can be synthesized by the following synthetic route.

[0032]

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Compound (20) can be synthesized by the following synthetic route.

[0034]

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Other compounds can be easily synthesized by the same synthesis method. The method of adding the compound represented by formula (1) of the present invention can be added according to a known addition method. Alcohols such as methanol and ethanol, ketones such as methyl ethyl ketone and acetone,
It can be added after being dissolved in a polar solvent such as dimethylsulfoxide and dimethylformamide. Also, 1μ
m or less and dispersed in water or an organic solvent. Although many techniques have been disclosed for the fine particle dispersion technique, they can be dispersed according to these techniques.

The binder of the heat-developable material of the present invention provides a place where the organic silver salt reacts with the blocked developer, and the oxidation-reduction reaction needs to proceed appropriately.
On the other hand, any action may be used as long as it blocks moisture during storage and suppresses redox. Such polymers are preferably hydrophobic rather than hydrophilic, for example, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, cellulose derivatives such as ethyl cellulose, starch and its derivatives, polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl butyral, poly Sodium acrylate, polyethylene oxide, acrylamide-acrylate copolymer,
Styrene-maleic anhydride copolymer, polyacrylamide, sodium alginate, gelatin, casein, polystyrene, polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylate, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, Examples thereof include a vinyl chloride-vinyl acetate copolymer and a styrene-butadiene-acryl copolymer. After drying and forming a film, the coating film preferably has a low equilibrium moisture content. Poly (acrylates) such as cellulose acetate, cellulose acetate butyrate, poly (methyl methacrylic acid), poly (acrylic acid), poly (methacrylic acid), poly (vinyl chloride), copoly (styrene-maleic anhydride) , Copoly (styrene-acrylonitrile), copoly (styrene-butadiene), poly (vinyl acetal) s (eg, poly (vinyl formal) and poly (vinyl butyral)), poly (ester) s, poly (urethane) s, phenoxy There are resins, poly (vinylidene chloride), poly (epoxides), poly (carbonates), poly (vinyl acetate), cellulose esters, and poly (amides).

The preferred polymer composition further has a glass transition point of -20 ° C. to 80 ° C., particularly -5 ° C.
To 60 ° C. This is because if the glass transition point is high, the temperature for thermal development becomes high, and if the glass transition point is low, fogging is liable to occur, resulting in a decrease in sensitivity and softness. The water-dispersed polymer is preferably dispersed as fine particles having an average particle diameter in the range of 1 nm to several μm. The water-dispersed hydrophobic polymer is called a latex and is widely used as a binder for water-based coating.
The amount of the latex used for the purpose of obtaining water resistance as a binder is determined in consideration of coatability, but is preferably as large as possible from the viewpoint of moisture resistance. The content is preferably 50% or more and 100% or less, and 80% or more and 100% or less based on the total binder mass.

Specific examples of the water-dispersed latex are shown as preferable polymers. Here, styrene is St, methyl acrylate is MA, methyl methacrylate is MMA, ethyl acrylate is EA, butyl acrylate is BA,
HA for hexyl acrylate, INA for isononyl acrylate, CA for cyclohexyl methacrylate, HEA for hydroxyethyl acrylate, HEMA for hydroxyethyl methacrylate, AA for acrylic acid, IA for itaconic acid, MA for maleic acid, MA for acrylamide AA
m, styrenesulfonic acid is St-S, acrylamide-
2-Methylpropanesulfonic acid amide is abbreviated as AMPS, isoprenesulfonic acid is abbreviated as IP-S, and 2-propenyl-4-nonylphenoxyethylene oxide (n = 10) sulfonic acid ester is abbreviated as PF-S. The accompanying figures represent the mass ratio of the monomer composition.

[0039]

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[0040]

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Although the use of the blocked compound of the present invention which is less affected by moisture is proposed, in order to obtain a heat-developable material having higher performance, select a polymer material containing as little water as possible after forming the coating film. It is necessary to do.

In the present invention, when the amount of the polymer binder in the photosensitive layer is 1/5 to 10 times the amount of silver and the amount of silver is 2.0 g / m ² , the amount of the polymer is It is preferably from 0.4 g to 20 g / m ² . More preferably 1 to 7 times the amount of half the amount per silver, if the amount per of silver 2.0 g / m ^2, a 1.0~14g / m ^2. If the amount is less than one-fifth of the amount of silver, the fog density is significantly increased, and it may not be usable. On the other hand, if the amount of silver is more than 10 times, it becomes soft and may not be usable.

The mechanism for promoting the imagewise release of the reducing agent by heat used in the present invention is based on the additives such as silver halide, organic silver salt, reducing agent, and precursor of the reducing agent used in the present invention. Can be controlled by controlling the abundance, position, and the like in the layer. In particular, the precursor compound used in the present invention, which releases a reducing agent by heat, has a structure in which the reducing function is suppressed until it is heated. After the development processing, the function of the reducing agent is developed and the non-image area is easily developed, so that it is necessary to prevent this. In the first method, the amount of the compound that releases a reducing agent by heat caused to be present in the photosensitive layer is 9 (the amount of the reducing agent equivalent to the amount of silver to be reduced) which is originally required for reduction.
This can be achieved by using a reducing agent that is not partially blocked, controlled at 9.0% to 60%. When the reduction of the part to be imaged by light is started, protons are released from the starting point and silver fine particles are formed so that the exposed part preferentially removes the blocking group of the precursor compound as much as possible in the image It is because it operates.
A heat developing material incorporating such a mechanism has improved high-temperature aging performance after development. It is desirable that the unblocked form of the reducing agent is 1% to 40%.
% Or more can be set by adjusting the pH of the system, controlling the crosslink density in the binder, the mobility of molecules, and the like.

The mechanism for releasing the reducing agent as in the second image can be controlled by using a photoacid generator. Generation of an acid by light promotes the removal of the blocking group from the blocked compound, so that the action of the reducing agent can be made image-like.

Known photoacid generators can be used. It releases a substance that makes the system acidic from the compound by light, but its action performance changes depending on the type of light. Although effective against ultraviolet light, the effect can be enhanced by using it in combination with a sensitizing dye or a sensitizing aid. For example, triphenylsulfonium hexafluoroantimony, di- (4-t-butylphenyl) iodonium-2-trifluoromethylbenzenesulfonate,
Di- (4-t-butylphenyl) iodonium perfluorooctanesulfonate, triphenylsulfonium perfluorooctanesulfonate, triarylsulfonium perfluorooctanesulfonate, N-[(perfluorooctanesulfonyl) oxy ] -Norborane-2,3-dicarboximide, 1,
1-bis [p-methoxyphenyl] -2,2,2-trichloroethane, 1,2,5,6,9,10-hexabulmocyclodecane, 1,10-dibromodecane, 1,1-
Bis [p-chlorophenyl] -2,2-dichloroethane, 4,4-dichloro-2- (trichloromethyl) benzhydrol (Kelthane), hexachlorodimethylsulfone, 2-chloro-6- (trichloromethyl)
Pyridine, O, O-diethyl-O- (3,5,6-trichloro-2-pyridyl) phosphorothionate, 1,2,2
3,4,5,6-hexachlorocyclohexane, N-
(1,1-bis [p-chlorophenyl] -2,2,2-
Trichloroethyl) acetamide, tris [2,3-dibromopropyl] isocyanurate, 2,2-bis [p
Photoacid generator compounds such as -chlorophenyl] -1,1-dichloroethylene, tris [trichloromethyl] -s-triazine and their isomers, analogs, homologues and other derivatives can be mentioned. Suitable photoacid generators are described in European Patent Applications 0164248 and 023.
No. 2972.

Onium salts are also preferred acid generators. Onium salts containing weak nucleophilic anions have been found to be particularly suitable. Examples of such anions are divalent to heptavalent metals or non-metals, such as Sb, Sn, Fe, B
i, Al, Ga, In, Ti, Zr, Sc, D, Cr,
It is a halogen complex anion including not only Hf and Cu but also B, P and As. Examples of suitable onium salts are diaryl-diazonium salts and onium salts of Groups V a and b, Groups I a and b and Group I of the Periodic Table, such as halonium salts, quaternary ammonium, phosphonium and arsonium. Salts, aromatic sulfonium salts and sulfoxonium salts or selenium salts, and the like, as disclosed in US Pat. No. 4,442,1
Nos. 97, 4,603, 101 and 4,62
No. 4,912.

Another group of suitable photoacid generators is the family of sulfonated esters, including sulfonyloxyketones. Suitable sulfonated esters are described in "Journal of Photopolymer Science and Technology" (J. of Photopolymer Science).
e and Technology), Vol. 4, No. 3, No. 3,
37-340 (1991), whose esters include benzoyl tosylate, t-butylphenyl alpha- (p-toluenesulfonyloxy) -acetate, and t-butyl alpha- (p-toluenesulfonyl). Oxy) -acetate.

The pH adjusting agent used in the present invention is preferably an acid agent which keeps the system acidic and hardly volatilizes. Examples of preferred acid agents include organic carboxylic acids, for example, citric acid, lactic acid,
Succinic acid, itaconic acid, tartaric acid, phthalic acid, monochlorophthalic acid, tetrachlorophthalic acid, p-toluenesulfonic acid, p-phenylsulfonylphenylsulfonylacetic acid,
Nitric acid, hydrochloric acid, sulfuric acid and the like of strong acids can be selected. At the time of manufacture, those which do not corrode equipment and those which promote absorption of moisture after film formation can be avoided and selected as appropriate.
Preferred acids are those having an aromatic ring, the aromatic ring being substituted with an electron-withdrawing group, and having a carboxylic acid group or a sulfonic acid group. Specifically, phthalic acid,
Chlorophthalic acid, cyanophthalic acid, methanesulfonylphthalic acid, fluorinated phthalic acid and the like. In addition, the aliphatic carboxylic acid also has 1 to 6 carbon atoms bonded to the carboxylic acid.
Those having an electron withdrawing group in the second range are preferred.
Examples thereof include p-chlorophenylsulfonylacetic acid, p-methoxyphenylsulfonylphenylpropaneacetic acid, and the like.

The light absorber used in the present invention may be IR
Immonium or diimmonium compounds such as G002 (manufactured by Nippon Kayaku Co., Ltd.) and IRG022 (manufactured by Nippon Kayaku Co., Ltd.), bisdithiobenzylnickel complex, toluenedithiolnickel complex, 4-tert-butyl-1,
Dithiolate-based nickel complexes such as 2-benzenedithiol nickel complex, indocyanine green (manufactured by Daiichi Pharmaceutical Co., Ltd.), NK-2014 (manufactured by Nippon Kogaku Dyestuff Research Laboratories), NK-2612 (manufactured by Nippon Kosen Co. Dye Laboratories), 1,1,5,5-tetrakis (p-dimethylaminophenyl) -3-methoxy-1,4-pentadienetoluene, 1,1,5,5-tetrakis (p-diethylaminophenyl)- Cyanine dyes such as 3-methoxy-1,4-pentadienetoluene, NK-2772
Squarylium dyes, naphthoquinone dyes, phthalocyanine dyes,
Examples include naphthalocyanine dyes and anthraquinone dyes. These light absorbers may be used in combination.

The organic acid of the metal salt of the organic acid used in the present invention includes o-benzoylbenzoic acid, o-alkyl-substituted benzoylbenzoic acid, o-alkylbenzoic acid, m-alkylbenzoic acid, o-toluylbenzoic acid And benzoic acids such as m-toluylbenzoic acid, o-halogenated benzoic acid and m-halogenated benzoic acid, and fatty acids such as acetic acid, propionic acid, stearic acid, behenic acid and palmitic acid. The metal of the metal salt of the organic acid is preferably silver, but iron, zinc, and the like can be appropriately selected.

In the present invention, if necessary, a sensitizer, an organic or inorganic filler, a wax, a sticking inhibitor, an ultraviolet absorber, an antioxidant, a water-proofing agent, a dispersant may be added to the heat-developable material. , An antifoaming agent, a fluorescent dye, a metal salt of a higher fatty acid, or the like.

Examples of the sensitizer include a series of heat-fusible organic compounds known as sensitizers known in thermal development, and any of them can be used.

As organic or inorganic pigments, silica,
Kaolin, calcined kaolin, diatomaceous earth, talc, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide,
Examples include aluminum hydroxide, urea-formalin resin, and styrene-methacrylic acid copolymer.

Japanese Patent Application Laid-Open (JP-A) No. Sho 60-210492 discloses that the dissociation temperature of a blocked developer is reduced by adding a metal salt of a higher fatty acid. In addition, a metal salt of a higher fatty acid such as caproic acid, caprylic acid, lauric acid, palmitic acid, stearic acid, behenic acid, and iron, zinc, copper, nickel, tin or the like may be contained. In this sense, the combination of the blocked developer and the metal salt of the organic acid is such that the metal salt of the organic acid is a developing material,
It also has the effect of lowering the dissociation temperature of the blocked developer, which is more preferable.

The types and amounts of the blocked developer, the organic silver salt, the silver halide salt, the light absorber, the binder, and other various components are determined according to the required performance and recording suitability, and are not particularly limited. However, 1 to 10 parts of a blocked developer, 0.5 to 5 parts of an organic silver salt, and 0.
01 to 1 part, the binder uses 0.5 to 10 parts in the total solid content, and the filler is suitably 2 to 15 parts. The amount of the blocked developer to be used is preferably 1 × 10 ^-2 to 10 per mol of silver.
Mol, especially 1 × 10 ^{−2 to} 5 mol.

The photothermographic material thus obtained is
By light or heat, the blocking group of the blocked developer is dissociated to develop a developing function, and immediately reacts with silver halide and an organic silver salt for development. Therefore, the present heat development material is a heat development material excellent in heat resistance and solvent resistance, which does not cause development unless the blocking group of the blocked developer is dissociated, does not cause unnecessary development by heat and solvent. .

The aqueous coating system of the present invention means that the ratio of the organic solvent to the water in the coating liquid composition is 0% or more and 40% or less, preferably 20% or less in the preparation of the coating liquid.
Furthermore, it means that a coating solution having a content of 10% or less, most preferably 5% or less, is used. When applying this coating liquid, the application method used is a slide hopper type,
Various appropriate methods such as a Meyer bar method, a roll coater method, and a vacuum extrusion method can be selected.

The photosensitive silver halide used in the heat-developable material of the present invention can be produced by any method known in the field of photographic technology such as a single jet or double jet method.
For example, it can be prepared by any method such as an ammonia method emulsion, a neutral method and an acid method. Thus, it can be prepared in advance and then mixed with other components of the present invention and introduced into the composition used in the present invention. In this case, in order to sufficiently contact the photosensitive silver halide with the organic silver salt, for example, US Pat. Nos. 3,706,564 and 3,706 as protective polymers for preparing photosensitive silver halide. , 565
No. 3,713,833, No. 3,748,14
No. 3, British Patent No. 1,362,970 or the like, a method using a polymer other than gelatin such as polyvinyl acetal, or a photosensitive halogen described in British Patent No. 1,354,186. Means for enzymatically decomposing gelatin in a silver halide emulsion, or US Pat. No. 4,076,53
As described in No. 9, various methods such as a method of omitting the use of a protective polymer by preparing photosensitive silver halide grains in the presence of a surfactant can be applied.

The silver halide functions as an optical sensor, and preferably has a small grain size in order to suppress white turbidity after image formation and to obtain good image quality. The average particle size is 0.1 μm or less, preferably 0.1 μm or less.
01 μm to 0.1 μm, especially 0.02 μm to 0.08 μ
m is preferred. The shape of the silver halide is not particularly limited, and may be cubic, octahedral, so-called normal crystals, or non-normal crystals, such as spherical, rod-shaped, or tabular grains. The silver halide composition is not particularly limited, and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide, and silver iodide.

The amount of silver halide is 50% or less, preferably 25% or less, based on the total amount of silver halide and the organic silver salt described below.
0.1%, more preferably between 15% and 0.1%.

The light-sensitive silver halide used in the heat-developable material of the present invention can also be used in preparing an organic silver salt as described in GB 1,447,454. By injecting silver ions into a halogen component such as an organic silver salt-forming component and injecting silver ions into the organic silver salt-forming component, it is possible to generate the organic silver salt almost simultaneously.

As still another method, a silver halide forming component is allowed to act on a solution or dispersion of an organic silver salt prepared in advance or a sheet material containing the organic silver salt to expose a part of the organic silver salt to light. It can also be converted to neutral silver halide.
The silver halide thus formed is in effective contact with the organic silver salt and exhibits a preferable action. A silver halide-forming component is a compound capable of forming a photosensitive silver halide by reacting with an organic silver salt, and which compound is applicable and effective is determined by the following simple test. be able to. That is, an organic silver salt is mixed with a compound to be tested, and if necessary, after heating, it is examined by an X-ray diffraction method whether there is a peak specific to silver halide. Silver halide-forming components confirmed to be effective by such tests include inorganic halides, onium halides, halogenated hydrocarbons, N-halogen compounds, and other halogen-containing compounds. Are U.S. Pat. Nos. 4,009,039 and 3,45
7,075, 4,003,749, British Patent 1,498,956 and JP-A-53-27027;
The details are described in JP-B Nos. 53-25420, and an example is shown below. (1) inorganic halide: For example, M is halide (here represented by MX _n, H, NH _4, and represents a metal atom, n represents 1 when the M is H and NH _4, M is a metal When it is an atom, it represents its valency, such as lithium,
Examples include sodium, potassium, cesium, magnesium, calcium, strontium, barium, zinc, cadmium, mercury, tin, antimony, chromium, manganese, iron, cobalt, nickel, rhodium, cerium, and the like. ).
Further, halogen molecules such as bromine water are also effective. (2) Onium halides: quaternary ammonium halides such as trimethylphenylammonium bromide, cetylethyldimethylammonium bromide, trimethylbenzylammonium bromide, quaternary phosphonium halides such as tetraethylphosphonium bromide, and trimethylsulfur There are tertiary sulfonium halides, such as phonium iodide. (3) Halogenated hydrocarbons: for example, iodoform,
Bromoform, carbon tetrachloride, 2-bromo-2-methylpropane and the like. (4) N-halogen compounds: For example, N-chlorosuccinimide, N-bromosuccinimide, N-bromophthalimide, N-bromoacetamide, N-iodosuccinimide, N-bromophthalazone, N-bromooxazolinone , N-chlorophthalazone, N-bromoacetanilide, N, N-dibromobenzenesulfonamide, N-bromo-N-methylbenzenesulfonamide, 1,3-dibromo-4,4-dimethylhydantoin, N-bromourazole and the like. (5) Other halogen-containing compounds: for example, triphenylmethyl chloride, triphenylmethyl bromide, 2-bromoacetic acid, 2-bromoethanol, dichlorobenzophenone and the like.

These silver halide forming components are used in a small amount stoichiometrically with respect to the organic silver salt. Usually, the range is from 0.001 mol to 0.7 mol, preferably from 0.03 mol to 0.5 mol, per 1 mol of the organic silver salt. Two or more silver halide forming components may be used in combination within the above range. Various conditions such as a reaction temperature, a reaction time, and a reaction pressure in the step of converting a part of the organic silver salt into silver halide using the above-mentioned silver halide forming component can be appropriately set according to the purpose of production. Usually, the reaction temperature is −20 ° C. to 70 ° C., the reaction time is 0.1 second to 72 hours, and the reaction pressure is preferably set to the atmospheric pressure.
This reaction is also preferably performed in the presence of a polymer used as a binder described below. The amount of the polymer used at this time is 0.01 to 10 parts by mass per part by mass of the organic silver salt.
0 parts by mass, preferably 0.1 to 10 parts by mass.

The photosensitive silver halide prepared by the various methods described above includes, for example, a sulfur-containing compound, a gold compound,
Platinum compounds, palladium compounds, silver compounds, tin compounds,
Chemical sensitization can be performed by a chromium compound or a combination thereof. The method and procedure of the chemical sensitization are described in, for example, U.S. Pat. No. 4,036,650, British Patent 1,518,850, and JP-A-51-22430.
No. 51-78319 and No. 51-81124. Also, when a part of the organic silver salt is converted to a photosensitive silver halide by a silver halide forming component, as described in U.S. Pat. An amide compound having a molecular weight may coexist.

In addition, these photosensitive silver halides may be used in order to prevent illuminance failure and to adjust the gradation.
Metals belonging to group III, such as Rh, Ru, Re, Ir, O
An ion such as s or Fe, a complex thereof or a complex ion can be contained. It is particularly preferable to contain ions or complex ions of metals belonging to Groups 6 to 10 of the periodic table. As the above metals, W, Fe, Co, Ni,
Cu, Ru, Rh, Pd, Re, Os, Ir, Pt, A
u is preferable, and when it is used for a photosensitive material for plate making, it is preferably selected from Rh, Re, Ru, Ir, and Os.

These metals can be introduced into the silver halide in the form of a complex. In the present invention, the transition metal complex is preferably a six-coordinate complex represented by the following general formula.

In the formula [ML ₆ ] ^m , M is a transition metal selected from elements of Groups 6 to 10 of the periodic table, L is a bridging ligand, and m is 0, 1-, 2- or 3
Represents-. Specific examples of the ligand represented by L include halides (fluoride, chloride, bromide and iodide), cyanide, cyanate, thiocyanate, selenocyanate, tellurocyanate, azide and aquo. Ligand, nitrosyl, thionitrosyl and the like, preferably aquo, nitrosyl and thionitrosyl. If an aquo ligand is present, it preferably occupies one or two of the ligands. L may be the same or different.

Particularly preferred examples of M are rhodium (Rh), ruthenium (Ru), rhenium (Re) and osmium (Os).

The content of metal ions or complex ions in the silver halide grains is generally selected from silver halide grains 1
1 × 10 ⁻⁹ to 1 × 10 ⁻² mol per mol is suitable,
Preferably it is 1 × 10 ^-8 to 1 × 10 ^-4 mol. The compound that provides the ion or complex ion of these metals is preferably added during silver halide grain formation and incorporated into the silver halide grains. Preparation of silver halide grains, that is, nucleation, growth, and physical ripening It may be added at any stage before and after chemical sensitization, but is particularly preferably added at the stage of nucleation, growth, and physical ripening, more preferably at the stage of nucleation and growth. Preferably, it is added at the stage of nucleation. During the addition, it may be added in several divided portions, may be added uniformly in the silver halide grains, or may be added, as disclosed in JP-A-63-29603.
JP-A-2-306236, JP-A-3-167545, JP-A-4-76534, JP-A-6-110146, and JP-A-5-27
As described in, for example, No. 3683, etc., the particles may be contained in the particles with a distribution. Preferably, a distribution can be provided inside the particles. These metal compounds can be added by dissolving them in water or a suitable organic solvent (eg, alcohols, ethers, glycols, ketones, esters, amides). Aqueous solution or metal compound and NaCl, K
A method in which an aqueous solution in which Cl is dissolved together is added to a water-soluble silver salt solution or a water-soluble halide solution during grain formation, or as a third aqueous solution when the silver salt solution and the halide solution are simultaneously mixed. A method of adding silver halide grains by a method of simultaneous mixing of three liquids, a method of charging a required amount of an aqueous solution of a metal compound into a reaction vessel during grain formation, or a method of preparing a metal ion or complex in advance during silver halide preparation. There is a method in which another silver halide grain doped with ions is added and dissolved. In particular, a method of adding an aqueous solution of a powder of a metal compound or an aqueous solution in which a metal compound and NaCl and KCl are dissolved together is added to a water-soluble halide solution. When adding to the particle surface, a required amount of an aqueous solution of a metal compound can be charged into the reaction vessel immediately after the formation of the particles, during or at the end of physical ripening, or at the time of chemical ripening.

In the present invention, a matting agent is preferably contained on the photosensitive layer side. In order to improve the dimensional repeatability of the present invention, a polymer matting agent or an inorganic matting agent is added to all binders on the emulsion layer side. , 0.5 to 10 by mass ratio
%.

The material of the matting agent used in the present invention may be either an organic substance or an inorganic substance. For example, as inorganic substances, silica described in Swiss Patent No. 330,158, glass powder described in French Patent No. 1,296,995, etc., and alkali described in British Patent No. 1,173,181 etc. An earth metal or a carbonate such as cadmium or zinc can be used as a matting agent. As organic matter,
Starch described in U.S. Pat. No. 2,322,037, Belgian Patent No. 625,451 and British Patent No. 981,19
No. 8 and the like, and starch derivatives described in JP-B-44-3643.
No. 33, Swiss Patent No. 33
No. 0,158, polystyrene or polymethacrylate; U.S. Pat. No. 3,079,257; polyacrylonitrile; U.S. Pat. No. 3,022,16.
An organic matting agent such as polycarbonate described in No. 9 or the like can be used.

The shape of the matting agent may be either regular or irregular, but is preferably regular and spherical. The size of the matting agent is represented by a diameter when the volume of the matting agent is converted into a sphere. In the present invention, the particle diameter of the matting agent indicates the diameter converted into a sphere.

The matting agent used in the present invention preferably has an average particle size of 0.5 μm to 10 μm, more preferably 1.0 μm to 8.0 μm. The matting agent has a coefficient of variation of the particle size distribution of preferably 50% or less, more preferably 40% or less, and particularly preferably 30% or less.

Here, the variation coefficient of the particle size distribution is a value represented by the following equation. (Standard deviation of particle size) / (average value of particle size) × 100 The matting agent according to the present invention can be contained in any constituent layer, but is preferably photosensitive in order to achieve the object of the present invention. It is a constituent layer other than the layer, more preferably the outermost layer as viewed from the support.

The method for adding the matting agent according to the present invention may be a method in which the matting agent is dispersed in a coating solution in advance and applied.
A method of spraying a matting agent after the application liquid is applied and before the drying is completed may be used. When a plurality of types of matting agents are added, both methods may be used in combination.

The heat-developable material of the present invention forms a photographic image by heat-development processing, and includes a reducible silver source (organic silver salt), a catalytically active amount of silver halide, a hydrazine derivative,
It is preferable that the heat developing material contains a color tone agent for suppressing the color tone of silver, if necessary, usually in a state dispersed in a (organic) binder matrix. The heat-developable material of the present invention is stable at room temperature, but is exposed to high temperature (for example, 8
(0 ° C. to 140 ° C.). Heating generates silver through an oxidation-reduction reaction between an organic silver salt (functioning as an oxidizing agent) and a reducing agent. This oxidation-reduction reaction is accelerated by the catalytic action of the latent image generated on the silver halide upon exposure. The silver formed by the reaction of the organic silver salt in the exposed areas provides a black image, which contrasts with the unexposed areas, resulting in the formation of an image. This reaction process proceeds without supplying a processing liquid such as water from the outside.

The heat development material of the present invention has at least one photosensitive layer on a support. Although only a photosensitive layer may be formed on the support, at least one photosensitive layer may be formed on the photosensitive layer.
Preferably, a non-photosensitive layer is formed. A filter layer may be formed on the same side as or opposite to the photosensitive layer to control the amount or wavelength distribution of light passing through the photosensitive layer, or the photosensitive layer may contain a dye or pigment. . The photosensitive layer may be composed of a plurality of layers, and the sensitivity may be changed to a high-sensitive layer / low-sensitive layer or a low-sensitive layer / high-sensitive layer for adjusting the gradation. Various additives may be added to any of the photosensitive layer, the non-photosensitive layer, and other forming layers. For example, a surfactant, an antioxidant, a stabilizer, a plasticizer, an ultraviolet absorber, a coating aid, and the like may be used in the heat-developable material of the present invention.

It is preferable to add a toning agent to the heat-developable material of the present invention. Examples of suitable toning agents are Research.
h Disclosure No. 17029, which includes:

Imides (eg, phthalimide); cyclic imides, pyrazolin-5-ones, and quinazolinones (eg, succinimide, 3-phenyl-2-pyrazolin-5-one, 1-phenylurazole, quinazoline and , 4-thiazolidinedione); naphthalimides (eg, N-hydroxy-1,8-naphthalimide); cobalt complexes (eg, hexamine trifluoroacetate of cobalt), mercaptans (eg, 3
-Mercapto-1,2,4-triazole); N- (aminomethyl) aryldicarboximides (for example,
N- (dimethylaminomethyl) phthalimide); blocked pyrazoles, isothiuronium (isoth
uronium) derivatives and certain photobleaching combinations (eg, N, N'-hexamethylene (1-carbamoyl-3,5-dimethylpyrazole), 1,8-
A combination of (3,6-dioxaoctane) bis (isothiuronium trifluoroacetate) and 2- (tribromomethylsulfonyl) benzothiazole; a merocyanine dye (e.g., 3-ethyl-5-((3-ethyl -2-benzothiazolinylidene (benzothiazolinylidene))-1-methylethylidene) -2-thio-2,4
-Oxazolidinedione); phthalazinone, a phthalazinone derivative or a metal salt of these derivatives (for example, 4-
(1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxyphthalazinone, and 2,3
-Dihydro-1,4-phthalazinedione); a combination of phthalazinone and a sulfinic acid derivative (for example, 6-chlorophthalazinone + sodium benzenesulfinate or 8-methylphthalazinone + sodium p-trisulfonate); phthalazine + phthalate Acid combinations; phthalazine (including phthalazine adducts) and maleic anhydride,
And phthalic acid, 2,3-naphthalenedicarboxylic acid or o
At least one selected from phenylene acid derivatives and anhydrides thereof (for example, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic anhydride);
Quinazolinediones, benzoxazines, naloxazine derivatives; benzoxazine-2,4-diones (eg, 1,3-benzoxazine-2,4-dione); pyrimidines and asymmetric triazines (E.g., 2,4-dihydroxypyrimidine) and tetraazapentalene derivatives (e.g., 3,
6-dimercapto-1,4-diphenyl-1H, 4H-
2,3a, 5,6a-tetraazapentalene). Preferred toning agents are phthalazone or phthalazine.

The heat development material of the present invention may contain an antifoggant. What is known as the most effective antifoggant is mercury ion. The use of a mercury compound as an antifoggant in a light-sensitive material is disclosed in, for example, US Pat. No. 3,589,903. However, mercury compounds are environmentally unfriendly. Non-mercury antifoggants include, for example, US Pat. No. 4,546,075.
No. 4,452,885 and JP-A-59-57.
Preferred are antifoggants such as those disclosed in US Pat.

Particularly preferred non-mercury antifoggants are described in US Pat. Nos. 3,874,946 and 4,756,99.
No.9, -C (X ₁ )
(X ₂ ) A heterocyclic compound having one or more substituents represented by (X ₃ ) (where X ₁ and X ₂ are halogen and X ₃ is hydrogen or halogen). Examples of suitable antifoggants include paragraphs [0062] to JP-A-9-90550.
The compounds described in [0063] are preferably used.

Further, more suitable antifoggants are disclosed in US Pat. No. 5,028,523 and British Patent Application No. 92221.
No. 383.4, No. 9300147.7, No. 931
No. 1790.1.

The heat-developable material of the present invention includes, for example,
No. 3-159841, No. 60-140335, No. 63
No.-231437, No.63-259651, No.63-
Nos. 304242, 63-15245, U.S. Pat. Nos. 4,639,414, 4,740,455, 4,741,966, 4,751,175,
Sensitizing dyes described in the above-mentioned 4,835,096 can be used. Useful sensitizing dyes for use in the present invention include, for example, R
search Disclosure Item17
Section 643 IV-A (p. 23, December 1978), It
em1831X (August 1978, p. 437). In particular, a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of various scanner light sources can be advantageously selected. For example, JP-A-9-
No. 34078, No. 9-54409, No. 9-80679
The compounds described in (1) are preferably used.

As the support, a support such as paper, synthetic paper, nonwoven fabric, metal foil, plastic film and the like can be used, and a composite sheet obtained by combining these can be used arbitrarily.

The coating solution can be obtained as follows. A dispersion in which a blocked developer represented by the general formula (1) is dispersed together with a binder, a dispersion in which an organic silver salt and silver halide are dispersed together with a binder, and a sensitizer further containing a light absorber Is mixed with a binder to obtain a coating solution. When this coating solution is coated on a support and dried, a heat-developable material can be obtained.

[0086]

EXAMPLES The present invention will be described below in detail with reference to examples, but embodiments of the present invention are not limited thereto. (Production of Thermal Developing Material) Example 1 [Preparation of Subbed Photographic Support] A polyethylene terephthalate support having a thickness of 130 μm was subjected to a corona discharge treatment of 8 w / m ² · min on both surfaces. Undercoating coating liquid a
-1 is applied to a dry film thickness of 0.8 μm and dried to form an undercoat layer A-1. On the other side, the undercoat coating solution b-1 shown below has a dry film thickness of 0.8 μm. The coating was dried as described above to obtain an undercoat layer B-1. << Undercoat Coating Solution a-1 >> Copolymer latex liquid of butyl acrylate (30% by mass), t-butyl acrylate (20% by mass), styrene (25% by mass), and 2-hydroxyethyl acrylate (25% by mass) (Solid content: 30%) 270 g Hexamethylene-1,6-bis (ethylene urea) 0.8 g Finish to 1 liter with water << Undercoat coating solution b-1 >> Butyl acrylate (40% by mass), styrene (20% by mass) ), Copolymer latex liquid of glycidyl acrylate (40% by mass) (solid content: 30%) 270 g Hexamethylene-1,6-bis (ethylene urea) 0.8 g Finished to 1 liter with water. 1 and the upper surface of the undercoat layer B-1,
A corona discharge of 8 w / m ² · min. Was performed, and the following lower coating liquid a-2 was coated on the lower coating layer A-1 with a dry film thickness of 0.1 μm.
The lower coating layer B-2 is coated with the following coating liquid b-2 on the lower coating layer B-1 so as to have a dry film thickness of 0.8 μm. Coated as B-2. << Undercoat upper layer coating solution a-2 >> Gelatin 0.4 g / m ² mass Silica particles (average particle size 3 μm) 0.1 g Finish to 1 liter with water << Lower undercoat upper layer coating solution b-2 >> Styrene butadiene Polymer latex liquid (solid content 20%) 80 g Polyethylene glycol (weight average molecular weight 600) 6 g Finish to 1 liter with water <Preparation of silver halide grain emulsion A> 7.5 g of inert gelatin and 10 mg of potassium bromide in 900 ml of water Was dissolved and adjusted to a temperature of 35 ° C. and a pH of 3.0, and 370 ml of an aqueous solution containing 74 g of silver nitrate and an aqueous solution containing potassium bromide and potassium iodide in a molar ratio of (98/2) (equimolar to silver) Amount) was added over 10 minutes by the controlled double jet method while maintaining the pAg at 7.7. Then 4
0.3 g of -hydroxy-6-methyl-1,3,3a, 7-tetrazaindene was added, the pH was adjusted to 5 with NaOH, the average particle size was 0.06 μm, and the variation coefficient of the projected diameter area was 8%. 100] Cubic silver iodobromide grains having an area ratio of 87% were obtained. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant, desalted, and then added with 0.1 g of phenoxyethanol.
The pH was adjusted to 5.9 and the pAg was adjusted to 7.5 to obtain a silver halide grain emulsion A. (Preparation of water-dispersed organic silver salt) Behenic acid (111.4 g), arachidic acid (83.8 g), and stearic acid (54.9 g) were dissolved in 4720 ml of pure water at 80 ° C. Next, a 1.5 mol / L aqueous sodium hydroxide solution 540.
After adding 2 ml and adding 6.9 ml of concentrated nitric acid, the mixture was cooled to 55 ° C. to obtain a sodium organic acid solution. While maintaining the temperature of the organic acid sodium acid solution at 55 ° C., the silver halide grain emulsion A (containing 0.038 mol of silver) and pure water 4
50 ml was added and stirred for 5 minutes. Next, 760.6 ml of a 1 mol / L silver nitrate solution was added over 2 minutes, the mixture was further stirred for 20 minutes, and water-soluble salts were removed by filtration. Thereafter, washing with deionized water and filtration were repeated until the conductivity of the filtrate reached 2 μS / cm, and water was added until the filtrate reached 1 L to finish. <Preparation of Coating Solution for Photosensitive Layer> The following layers were sequentially formed on the support provided with the undercoat layer described above to prepare a sample. In addition, each drying was performed at 75 ° C. for 1 minute. Back side coating Back layer: A coating solution prepared by adding an aqueous solution or aqueous dispersion of the following composition to water was applied and dried so as to have the following coating amount.

Polyvinyl alcohol PVA205 Kuraray Co., Ltd. 2.0 g / m ² Dye C 70 mg / m ² Back layer protective film Inert gelatin 0.8 g / m ² Matting agent (PMMA: average particle diameter 3 μ) 0.02 g / m ² Surfactant: N-propyloctylsulfonamidoacetic acid 0.02 g / m ² Hardener: 1,2- (bisvinylsulfonamido) ethane 0.02 g / m ² Coating on photosensitive layer surface The preparation of the photosensitive layer has the following composition The aqueous dispersion of the product was added to water to prepare a coating solution. The coating solution was kept at 35 ° C., and Ag / AgCl in a 3 mol / L solution was passed through a salt bridge composed of a silver electrode (purity of 99.99% or more) and a 10% KNO ₃ salt solution.
The silver potential was measured using a silver electrometer formed from a reference electrode composed of an electrode, and then applied and dried so that the following amount was obtained.

A preparation solution of silver halide and an organic silver salt in an amount of 1.4 g / m ² in terms of silver was mixed with a polymer binder. The silver halide was added so as to be 1/10 equivalent to the organic silver salt.

[0089] Polyvinyl alcohol as binder (molecular weight: 40,000) 5.6 g / m ² sensitizing dye -1 12 mg / m ² antifoggant -1: pyridinium hydrobromide perbromide 0.3 mg / m ² antifoggant -2 : isothiazolone 1.2 mg / m ² antifoggant -3: 2-tribromomethylsulfonyl quinoline 120 mg / m ² phthalazone 360 mg / m ² developer: pH of 3.3 mmol / m ² photosensitive layer coating solution shown in Table 1 Was adjusted to 5.6. Surface protective layer: A coating solution prepared by adding an aqueous solution or a water dispersion of the following composition to water was applied and dried so as to have the following amount.

Inert gelatin 1.2 g / m ² Phthalazine 1.0 g / m ² 4-Methylphthalic acid 0.72 g / m ² Tetrachlorophthalic acid 0.22 g / m ² Tetrachlorophthalic anhydride 0.5 g / m ² Silica matting agent (average particle size 5 μm) 0.5 g / m ² 1,2- (bisvinylsulfone acetamide) ethane 0.3 g / m ²

[0091]

Embedded image

<< Evaluation of Photographic Performance >> Samples were prepared by suspending the coating solution containing the additives up to the developer for 1 hour and 24 hours. The stagnation performance was measured by measuring the difference in the rise in undeveloped heat development fog after the application of the photosensitive layer solution when the coating solution was stagnated for 1 hour and 24 hours. The angle between the exposed surface of the heat developing material and the exposed laser beam was 76 degrees. The room temperature test was performed after the coated and dried thermal developing material was placed in an atmosphere of 25 ° C. and 48% RH for 24 hours. 45 ° C 48% R as high temperature test
After storing for 3 days in an atmosphere of H, the same evaluation as above was performed.

The heat developing materials prepared as the stagnation test sample, the room temperature test sample, and the high temperature test sample were exposed with a laser sensitometer having a semiconductor laser of 810 nm, and then heat-developed at 120 ° C. for 8 seconds using a heat drum. Processed. At that time, exposure and development were performed in a room conditioned at 25 ° C. and 48% RH. Evaluation (sensitivity, fog, and maximum density (Dmax)) of the obtained image was performed using a densitometer. The sensitivity was evaluated by the reciprocal of the ratio of the exposure amount giving a density 0.3 higher than the fog (minimum) density (Dmin). It was expressed by relative evaluation with reference to 1.

Table 1 shows the results of the evaluation.

[0095]

[Table 1]

[0096]

Embedded image

When the blocked developer of the present invention is used, development does not occur unless the blocking group of the blocked developer is dissociated. Therefore, it can be seen that the fog is lower than that of the conventional one even when the coating solution is stagnated. Further, it is possible to obtain a heat-developable material having excellent storage stability over time and high-temperature storage stability.

Example 2 A heat-developable material was prepared in the same manner as in Example 1, except that the type and amount of the polymer binder were changed as shown in Table 2 in the preparation of the photosensitive layer instead of polyvinyl alcohol. As the developer, the blocked developer of the present invention ((5) of the compound of the general formula (1) of the present invention) was used. In order to improve the charging characteristics and the surface smoothness of the protective layer of the emulsion layer and the backing layer, sodium perfluorooctyl sulfonate as a fluorine-based surfactant was added at 0.2 g / m 2.
² was added. Table 2 shows the results.

[0099]

[Table 2]

From the results shown in Table 2, according to the present invention, when the amount of the polymer (hydrophobic latex) is changed from 1/5 to 10 times the amount of silver in the photosensitive layer, heat development at high temperature is low. It can be seen that the material can be provided. It can be seen that when the amount exceeds the range of the invention, fog increases and sensitivity decreases.

Example 3 A heat-developable material was prepared in the same manner as in Example 1, except that a photoacid generator was used as shown in Table 3 when a mixed coating solution of silver halide, silver behenate and developer was prepared. Was added and the pH was adjusted. As the developer, the blocked developer of the present invention ((4) of the compound of the general formula (1) of the present invention) was used. After the coating solution thus prepared was kept at 35 ° C. for 1 hour and 24 hours, a photosensitive material was prepared, and the fog density and sensitivity were measured. Table 3 shows the results.

[0102]

[Table 3]

From the results shown in Table 3, it can be seen that the present invention can provide a heat-developable material having low fog and high sensitivity by maintaining the pH at 5 or more and 2 or more.

Example 4 A photosensitive material was prepared in the same manner as in Example 1. However, when the blocked developer (reducing agent precursor compound) of the present invention, which releases a reducing agent by heat, was added, the corresponding material was used. Thermal development was performed by changing the amount of the reducing agent compound (without the blocking group) as shown in the following table. The amount added was expressed as a relative percentage. Developed photosensitive material at 45 ° C and 48% R
Fog and sensitivity after standing for 5 days in an atmosphere of H
The fog and the sensitivity after storage for 5 days in an atmosphere of 48% RH at 40 ° C. were compared. Table 4 shows the results.

[0105]

[Table 4]

From the results shown in Table 4, the blocked developer (precursor compound) of the present invention which releases the reducing agent by heat as a mechanism for promoting the imagewise release of the reducing agent by heat and its blocking group It can be seen that the high-temperature preservability is improved by controlling the ratio of the amount used to the reduced form desorbed.

Example 5 A heat-developable material was prepared in the same manner as in Example 1, except that a quarter mole of the blocked developer (precursor compound) of the present invention, which releases a reducing agent by heat, was used. A thermal developing material was prepared by adding an amount of the photoacid generator. After developing this, 45 ° C
Under fluorescent light of 200 lux in a room of 48% RH (medium light color 4
(0 Watt: National FLR40SD / M-X) and the fog and sensitivity after being left for 6 days were compared with the fog and sensitivity after storage for 6 days in an atmosphere of 25 ° C. and 48% RH. Table 5 shows the results.

[0108]

[Table 5]

(A): triphenylsulfonium hexafluoroantimony (B): di- (4-t-butylphenyl) iodonium-2-trifluoromethylbenzenesulfonate (C): di- (4-t-butyl) Phenyl) iodonium perfluorooctanesulfonate (D): triphenylsulfonium perfluorooctanesulfonate. From the results in Table 5, as a mechanism for promoting imagewise release of a reducing agent by heat,
It turns out that the use of the photoacid generator is effective.

Example 6 A heat-developable material was prepared in the same manner as in Example 2, except that the glass transition point of the polymer used was changed, and the blocked developer (14) of the present invention was used. The high temperature storability after imagewise exposure and development was evaluated. The fog and sensitivity of the developed photosensitive material after standing for 5 days in an atmosphere of 45 ° C. and 48% RH were compared with the fog and sensitivity after storage for 5 days in an atmosphere of 25 ° C. and 48% RH. Table 6 shows the results.

[0111]

[Table 6]

The glass transition point of the polymer is from 0 ° C. to 60 ° C.
It can be seen that up to the above is preferable in terms of fog and sensitivity and high-temperature storage stability.

[0113]

According to the present invention, despite the water-based coating method, low fog, a high density can be obtained, a high-quality image with favorable contrast can be obtained, and the fog has a low fog even under high temperature storage. A developing material can be provided.

Claims (5)

[Claims] 1. A heat-developable material having a photosensitive layer containing photosensitive silver halide grains on at least one surface of a support, wherein at least one of the photosensitive layer and the non-photosensitive layer contains an organic silver salt and a nitrogen-containing aromatic compound. A heat-developable material containing a reducing agent blocked with a group containing a group. 2. A heat-developable material having a photosensitive layer containing photosensitive silver halide grains on at least one surface of a support, wherein at least one of the photosensitive layer and the non-photosensitive layer contains an organic silver salt and a nitrogen-containing aromatic compound. A heat-developable material comprising a reducing agent blocked by a group containing a group and a mechanism for promoting imagewise release of the reducing agent by heat. 3. The heat-developable material according to claim 1, wherein the reducing agent blocked with a group containing a nitrogen-containing aromatic group is represented by the following general formula (1). Embedded image [In the formula, Ar represents an aryl group. X represents an oxygen atom, a sulfur atom or an amino group, R represents a group containing a nitrogen-containing aromatic group, and n and m are each an integer of 0 or 1. ] 4. The method according to claim 1, wherein the mass ratio of the hydrophobic latex in the layer containing the organic silver salt is 1/5 to 10 times the silver amount. Heat development material. 5. The heat development method according to claim 1, wherein a pH adjusting agent is contained in a layer adjacent to the photosensitive layer, and the pH in the film of the photosensitive layer is kept at 2 or more and 5 or less. material.