JP2001083654A - Heat developable photosensitive material with improved silver tone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat developable photosensitive material giving a high quality image excellent in silver tone and having high image density and good contrast whether water coating or solvent coating is carried out, and which is less liable to deteriorate silver tone even in storage at high humidity. SOLUTION: The heat developable photosensitive material contains photosensitive silver halide grains, an organic silver salt and a reducing agent for the silver salt in one layer or plural layers on at least one face of the substrate and contains at least one compound which releases an intra- or interlayer movable phthalazin derivative under heat in the layer or at least one layer adjacent to the layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photothermographic material which forms an image by thermal development, and more particularly to obtaining a high image quality excellent in silver tone even when produced by aqueous coating or solvent coating. The present invention relates to a photothermographic material having excellent storage stability, and having little change in silver tone even when stored under high humidity.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for a photothermographic material which does not cause waste liquid due to wet processing of a photographic material in the fields of medical treatment and printing in view of environmental protection and workability. As this technique, for example, U.S. Pat.
7,075 and D.C. “Dry Silver Photographic Materials (Dry Silver P) by Morgan
photographic Materials) ”(H
andbook of Imaging Materi
als, Marcel Dekker, Inc. Forty-eighth
1991) is well known. Since these photosensitive materials are usually developed at a temperature of 80 ° C. or higher, they are called photothermographic materials.

Conventionally, most photothermographic materials of this type have been manufactured by applying a solvent. The reason for this is that in a photosensitive layer coated with a mixture of a developer and an organic silver salt by aqueous coating, the oxidation-reduction reaction gradually proceeds with water as a medium, and the silver tone deteriorates. In a non-aqueous system, such degradation is small because the water-mediated oxidation-reduction reaction is suppressed. Until now, a large number of compounds that improve the silver tone and suppress the deterioration of the color tone have been searched so far, and phthalazine derivatives have attracted attention as a particularly effective compound for improving the silver tone, for example, see JP-A-10-339930. JP, JP-A-10-33993
No. 1 and JP-A-11-49756.

[0004] However, even with the use of these phthalazine derivatives, the performance relating to silver tone is not sufficient. Further, when a forced raw preservability test is carried out, disadvantages such as a decrease in image density and a deterioration in color tone cannot be completely solved, and this tendency is particularly strong in a humid state. Further, they have poor storage stability after heat treatment, and have disadvantages such as a decrease in image density and a deterioration in color tone.

[0005] When these phthalazine derivatives are used in aqueous coatings, the performance is naturally not always sufficient, and problems such as a decrease in image density and a deterioration in color tone by a forced raw storage test and a storage stability after heat treatment are found. Has not been improved.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photothermographic material which has an excellent silver tone, a high image density, and a high quality image having a preferable contrast even in aqueous coating and solvent coating. It is an object of the present invention to provide a photothermographic material which is capable of producing a photothermographic material having a low silver tone even when stored under high humidity.

[0007]

The above object is achieved by the following means.

[0008] 1. A photothermographic material comprising at least one surface of a support containing photosensitive silver halide grains, an organic silver salt and a reducing agent for the organic silver salt in one layer or in a plurality of layers; And a photothermographic material characterized in that at least one of the layers adjacent to the layer contains at least one compound which releases a phthalazine derivative which is movable in or between layers by heat.

[0009] 2. A photothermographic material comprising a photothermographic layer having at least one surface of a support having photosensitive silver halide grains, an organic silver salt and a reducing agent for the organic silver salt, wherein the photothermographic layer or A photothermographic material comprising, in a layer adjacent to the photothermographic material, at least one compound which releases a phthalazine derivative which is movable in or between layers by heat.

[0010] 3. 3. The photothermographic material according to item 1 or 2, wherein a compound that releases a phthalazine derivative is present in the latex.

4. (1) The compound as described in (1) or (2) above, wherein a compound releasing a phthalazine derivative is present in the wax.
2. The photothermographic material according to item 1.

5. 3. The photothermographic material according to the above item 1 or 2, wherein the compound releasing the phthalazine derivative is present in fine particles having voids.

6. 3. The photothermographic material according to item 1 or 2, wherein the compound that releases the phthalazine derivative is present in the photothermographic material in the form of fine particles.

7. 7. An image recording method, wherein an exposure is performed by a laser scanning exposure machine in which an angle between an exposure surface of the photothermographic material and the scanning laser beam is not substantially perpendicular.

[8] 7. An image recording method, wherein an exposure surface of the photothermographic material according to any one of 1 to 6 and a scanning laser beam are exposed by a laser scanning exposing machine in which the scanning laser beam is a vertical multi.

Hereinafter, embodiments of the present invention will be described in detail. In a photothermographic material (hereinafter sometimes simply referred to as a "photosensitive material"), a photosensitive layer containing silver halide grains usually contains an organic silver salt, an organic silver salt reducing agent, and a silver tone agent. A color tone agent such as phthalazine has an effect of improving the color tone of silver produced by an oxidation-reduction reaction of an organic silver salt and a reducing agent, and at the same time, has an effect of accelerating the oxidation-reduction reaction. Therefore, in the presence of phthalazine, the reducing agent gradually reduces silver halide or organic silver salt during storage, especially under high humidity.

Therefore, not only in the case of aqueous coating, but also in the case of non-aqueous coating, when exposed to high humidity conditions, etc.
During the stagnation of the coating solution, the generation of fog nuclei due to the contact between the organic silver salt and the reducing agent is accelerated in the presence of phthalazine, so that the silver color of the light-sensitive material is poor, fogging is easy, sensitivity is low, and storage stability is low. However, problems such as poor silver tone remarkable deterioration occur. Therefore, it is necessary to suppress the oxidation-reduction reaction that leads to fog nucleation in which silver halide, organic silver salt, reducing agent and silver toning agent cooperate between the preparation of the coating solution and the drying of the photosensitive material. If it can be suppressed by the above, it is considered that the preservability can be improved. However, if suppression is applied, the development activity will be reduced. In the present invention, in order to avoid this, by using a precursor compound that releases the silver toning agent in a timely manner by heat during development, the storage stability of the photothermographic material with respect to the silver tone can be improved without lowering the developing activity. It turns out that it can be enhanced. A compound that releases a silver toning agent, that is, a silver releasing compound precursor is a compound that is initially ballasted and does not effectively act as a toning agent, but effectively acts as a toning agent after the ballast is released by heat. It becomes a compound which can be obtained. When such a compound is used, it is contained in a state where it does not act as a color-toning agent at the time of coating and drying, or at the time of storage of the light-sensitive material, thereby causing an increase in fog, a decrease in sensitivity, a deterioration in color tone, and the like. The formation of fogging nuclei is unlikely to occur, and once the ballast is released and phthalazine is released by the thermal development process,
By exhibiting the function of the original color tone agent, it accelerates development and improves color tone, and suppresses fog nucleation during storage during production, resulting in low fog, high sensitivity, and thermal development. Later storage stability can also be improved.

The precursor compound from which the color toning agent is released by the heat is a phthalazine compound having a ballast group necessary for immobilizing the phthalazine in a phthalazine residue. The phthalazine is heat or acid. Is a compound having a removable ballast group, which releases a phthalazine derivative which is movable in a layer or between layers by releasing a ballast group. The leaving ballast group is required to be a bulky group necessary for immobilizing the compound. Generally, these immobilizing groups include alkyl groups having 4 or more carbon atoms,
An aryl group having an alkyl group having 3 or more carbon atoms, or a heterocyclic group, wherein the alkyl group is defined to include a cycloalkyl group, a bicycloalkyl group, and the like.

These leaving ballast groups are connected to the phthalazine nucleus via various bonds. Examples of these linking groups include various bonding groups such as an ether bond, a carbonate bond and a urethane bond. . Depending on the types and properties of these bonds, substituents such as a hydroxyl group, a carboxylic acid group, and an amino group may be left on the phthalazine nucleus, but these substituents do not inhibit the action of phthalazine as a color tone agent. Any substituent may be used. In some cases, traces of ballast groups are not left on the phthalazine nucleus due to decarboxylation or the like. These compounds are functionally represented by the following general formula.

Formula (1) (K) _m -PZ (wherein K represents a substituent capable of leaving by heating, m represents an integer of 1 or more and 4 or less. When m ≧ 2, a plurality of K May be the same or different.PZ represents a phthalazine nucleus, which may have an electron-withdrawing or electron-donating substituent on the phthalazine nucleus.) Any derivative may be used as long as it exhibits a function as a toning agent. The derivative may have an electron-withdrawing substituent or an electron-donating substituent on the phthalazine nucleus. Examples of the electron-withdrawing group and the electron-donating group which may be respectively substituted include, for example, C1 to C1.
25, an alkyl group (methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, cyclohexyl group, etc.), having 1 to 2 carbon atoms
5, a cycloalkyl group (eg, cyclohexyl group, cyclopentyl group), an alkynyl group (eg, propargyl group), an aryl group (eg, phenyl group), a heterocyclic group (eg, pyridyl group) having 1 to 25 carbon atoms , A thiazolyl group, an oxazolyl group, an imidazolyl group, a furyl group, a pyrrolyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a selenazolyl group, a siriphoranyl group, a piperidinyl group, a pyrazolyl group, a tetrazolyl group, a halogen atom (for example, a chlorine atom, Bromine atom, iodine atom, fluorine atom, etc., alkoxy group (eg, methoxy group, ethoxy group, propyloxy group, pentyloxy group, cyclopentyloxy group, hexyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group) Group), alkoxycarbo (For example, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, etc.), aryloxycarbonyl group (for example, phenyloxycarbonyl group, etc.), sulfonamide group (for example, methanesulfonamide group, ethanesulfonamide Group, butanesulfonamide group, hexanesulfonamide group, cyclohexanesulfonamide group, benzenesulfonamide group, etc.), sulfamoyl group (for example,
Aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group,
A hexylaminosulfonyl group, a cyclohexylaminosulfonyl group, a phenylaminosulfonyl group, a 2-pyridylaminosulfonyl group, etc., a ureido group (for example, a methylureido group, an ethylureido group, a pentylureido group, a cyclohexylureido group, a phenylureido group,
2-pyridylureido group, etc.), acyl group (eg, acetyl group, propionyl group, butanoyl group, hexanoyl group, cyclohexanoyl group, benzoyl group, pyridinoyl group, etc.), 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, acetamido group, propionamido group, butanamide group, Hexane amide group,
A benzamide group, 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, Dimethylamino group, butylamino group, cyclopentylamino group, anilino group,
2-pyridylamino group), cyano group, nitro group, sulfo group, carboxyl group, hydroxyl group, oxamoyl group and the like. These groups may be further substituted with these groups.

The compound in which the phthalazine is substituted with a removable ballast group and the ballast group is released by heat or acid is preferably a compound represented by the following general formulas (1a) and (1b).

Formula (1a) PZ- (OCOOR ₁ ) _m Formula (1b) PZ- (OCONHR ₁ ) _m wherein PZ represents a phthalazine mother nucleus as described above, and R ₁ represents the phthalazine compound. A group having a bulk necessary for immobilizing a phthalazine compound in each layer of the photothermographic material including the photothermographic layer, preferably an alkyl group having 4 or more carbon atoms, and an alkyl group having 3 or more carbon atoms. Represents an aryl group heterocyclic group having an alkyl group. m represents an integer of 1 or more and 4 or less. When m ≧ 2, a plurality of R ₁ may be the same or different.

Examples of these alkyl groups include isobutyl, tert-butyl, hexyl, tert-octyl, nonyl, dodecyl, hexadecyl, octadecyl, cyclohexyl, cyclopentyl and the like. Alicyclic containing a bicyclo ring such as a cycloalkyl group, an adamantyl group, a 1-methyladamantan-1-yl group, a tetracyclododecyl group, a tricyclodecanyl group, a mentyl group, an isobornyl group, etc. Group.

The aryl group containing an alkyl group having 3 or more carbon atoms and the heterocyclic group include bulky groups such as a p-tertbutylphenyl group and a 2,4-di-tert-pentylphenyl group. Examples include a heterocyclic group such as an aryl group and a 2,3-diisopropylpyrazolyl group.
These alkyl groups, aryl groups, and heterocyclic groups may be further substituted with various electron-withdrawing or electron-donating substituents mentioned as the substituents of phthalazine.

These compounds release these ballast groups (immobilizing groups) during thermal development to release phthalazine derivatives. In this case, the phthalazine compound having a hydroxyl group is released by decomposing between the oxygen atom and the carbonyl group of the urethane group and the alkoxyester group in the above structure. The elimination of these ballast groups proceeds by heat, and is accelerated by the presence of protons that are released with the progress of development in the developing section during thermal development.

The compounds represented by the general formulas (1a) and (1b) of the present invention have a structure in which a ballasting group is substituted for a hydroxyl group of a compound in which an aromatic ring of phthalazine is substituted with a hydroxyl group. . It is preferable that at least one of the substituents adjacent to the blocked hydroxyl group is substituted with an optionally substituted alkyl group having 1 to 35 carbon atoms. In particular, when the substituent adjacent to the hydroxyl group is a bulky group, thermal elimination is promoted. Therefore, it is preferable to introduce a bulky substituent in order to promote the elimination. The bulky substituent is preferably disposed on both sides adjacent to the hydroxyl group, but may be separated or may be introduced on one side of the hydroxyl group. Examples of the bulky substituent include a tert-butyl group, a tert-amyl group, an adamantyl group, a 1-methyladamantan-1-yl group, a 4-methyllactone-1-yl group, a tetracyclododecyl group, and a tricyclodecanyl group. , A menthyl group, an isobornyl group, and the like. Promoting elimination with such a bulky substituent can be referred to as sterically accelerated elimination.

Specific examples of the compounds represented by formulas (1a) and (1b) are shown below.

[0028]

Embedded image

[0029]

Embedded image

[0030]

Embedded image

[0031]

Embedded image

The above general formula (1a) used in the present invention,
The phthalazine silver toning agent having a removable ballast group represented by (1b) is obtained by introducing a urethane group or a carbonic acid group into a phthalazine mother nucleus as a group which is released by heat. These compounds can be synthesized based on phthalazine having a hydroxyl group. A method for blocking a hydroxyl group is disclosed in JP-A-4-144.
No. 787, a method of adding an isocyanate compound to a phenol compound, a method of converting a phthalazine compound having a hydroxyl group into an aryl chloroformate compound, and then condensing the aryl chloroformate compound with amines. Or can be produced using carbonate esters. Further, it can be synthesized by a method according to the specification of JP-A-6-183153.

These phthalazine derivatives having a ballast group which is released by heat or acid are hereinafter referred to as ballasted phthalazine.

In a photothermographic material using ballasted phthalazine, the color tone depends on the desorption temperature of the ballast group of the ballasted phthalazine. Therefore, the desorption temperature of the ballast group is determined in terms of the silver color tone of the photothermographic material. It is an important factor. For this reason, it is desirable that the desorption temperature of the ballast group of the blocked phthalazine used in the photothermographic material of the present invention is as low as possible.

In order to lower the desorption temperature of the ballast group of the ballasted phthalazine, it is first necessary to optimally set the balance between hydrophilicity and hydrophobicity of the binder on the aromatic nucleus side of phthalazine having a color tone function. Due to the good affinity of the binder and the toning agent portion, the dissolution of the ballasted phthalazine in the binder upon heating is promoted, so that the reaction of the deballasting group upon heating proceeds smoothly,
Elimination of the ballast group can be advantageously performed.

In this case, the ballast group can be advantageously eliminated by using an acid generator or the like.

The phthalazine derivative from which the ballast group has been eliminated has a reduced molecular weight so that it can be easily moved in the layer. The phthalazine derivative which has become mobile is adsorbed on the developed silver filament by approaching the silver halide. At the same time, the dissolution of the organic silver salt is promoted, and the supply of silver ions is actively promoted to promote the development and improve the silver tone. In the ballasted state, the phthalazine compound cannot effectively supply silver ions for enhancing the developing activity.

In general, the compound of the present invention is most preferably in the vicinity of a silver halide of a photothermographic layer containing silver halide, an organic silver salt, a reducing agent and the like. May be contained in a non-photosensitive layer, an intermediate layer, a protective layer, and the like adjacent to. These can be set so as to be in contact with the photothermographic layer and to move between layers to affect the storage stability.

Further, for example, in the case of a light-sensitive material in which any one of silver halide grains, organic silver salt, reducing agent and the like is divided and coated in a plurality of layers, the essential point is that the organic silver salt When considering a system in which the reaction of a reducing agent is accelerated by a toning agent, even if these are contained in an adjacent layer separated from a layer having either an organic silver salt, a reducing agent, or a silver halide component, a ballast group is formed. Since the phthalazine derivative released from the ballasted phthalazine when it comes off can move between layers, it participates in the reaction between the organic silver salt and the reducing agent on the silver halide and in any layer as long as the color tone can be blackened. It may be present. Further, even if it is contained in a layer provided separately from a plurality of layers containing these components, the phthalazine derivative released at the time of thermal development can diffuse between the layers.

The compound of the present invention can be added according to a known addition method. That is, it can be added by dissolving in alcohols such as methanol and ethanol, ketones such as methyl ethyl ketone and acetone, and polar solvents such as dimethyl sulfoxide and dimethylformamide. In addition, sand mill dispersion and jet mill dispersion,
Fine particles having a particle size of 1 μm or less can be added by dispersing in water or an organic solvent by ultrasonic dispersion or homogenizer dispersion. Although many techniques have been disclosed for the fine particle dispersion technique, they can be dispersed according to these techniques.

Various binders can be used as the binder for the photothermographic material of the present invention. Examples of the binder include cellulose derivatives such as hydroxyethylcellulose, carboxymethylcellulose, methylcellulose and ethylcellulose.
Starch and derivatives thereof, polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl butyral, sodium polyacrylate, polyethylene oxide, acrylamide-acrylate copolymer, styrene-maleic anhydride copolymer, acrylonitrile-butadiene copolymer, Examples thereof include a vinyl chloride-acetyl-partil copolymer and a styrene-butadiene-acrylic acid copolymer. However, the binder of the photothermographic material provides a place where the silver halide and the organic silver salt are adsorbed and reacted with the ballasted phthalazine, and the oxidation and reduction of the silver halide and the organic silver salt accelerated by the toning agent. It is necessary for the reaction to proceed properly, and the ballast group is eliminated, and phthalazine diffuses properly in the layer after thermal development and adsorbs on silver to act to increase the color tone of silver in the blackening direction. It is sufficient if the polymer has no diffusivity during storage and suppresses the reduction of silver halide. Such a polymer is preferably a hydrophobic polymer rather than a hydrophilic polymer. For example, polyvinyl alcohol (polyvinyl alcohol has a rather hydrophobic property rather than a hydrophilic property as a film due to strong hydrogen bonding between polymer chains), modified polyvinyl alcohol, polyvinyl butyral, cellulose esters, acrylamide-
Acrylic ester copolymer, styrene-maleic anhydride copolymer, acrylonitrile-butadiene copolymer,
Examples thereof include a vinyl chloride-acetyl-partil copolymer and a styrene-butadiene-acrylic acid copolymer. Further, after drying and forming a film, the coating film preferably has a low equilibrium moisture content. These include cellulose acetate, cellulose acetate butyrate, poly (acrylate esters), poly (vinyl chloride), copoly (styrene-maleic anhydride), copoly (styrene-acrylonitrile), copoly (styrene-butadiene) , Polyvinyl acetals (eg, polyvinyl formal, polyvinyl butyral), polyesters, polyurethanes, phenoxy resins, polyvinylidene chloride, polyepoxides, polycarbonates, polyvinyl acetate,
There are polyamides.

When the aqueous coating is performed, an aqueous latex can be used as a preferable polymer. These constitute an aqueous coating solution, but form a uniform polymer film at the stage of forming a coating film by drying after coating. When these are used, therefore, the heat-developable photosensitive layer is formed by applying an organic reduced salt, silver halide, a reducing agent, and the like as an aqueous dispersion, mixing with these latexes to form a uniform dispersion, and applying the dispersion. Form. Upon drying, the latex coalesces the particles to form a uniform film.

With respect to a preferred polymer composition, the glass transition point is more preferably from -20 ° C to 80 ° C,
Preferably from 5 ° C to 60 ° C. The higher the glass transition point, the higher the temperature for thermal development, and the lower the temperature, the easier it is to fog,
This is because the sensitivity is lowered or becomes soft. 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 among those widely used as a binder for aqueous coating, a latex that improves water resistance is preferable. The amount of latex used for obtaining water resistance as a binder is preferably as large as possible from the viewpoint of moisture resistance determined in consideration of coatability. The content is preferably 50% or more and 100% or less, and 80% or more and 100% or less based on the total binder weight.

Specific examples of preferred water-dispersed latex polymers are shown below. Here, styrene is St, methyl acrylate is MA, isononyl acrylate is INA, cyclohexyl methacrylate is CA, hydroxyethyl acrylate is HEA, and hydroxyethyl methacrylate is HEMA. AA for acrylic acid, IA for itaconic acid,
MA for maleic acid, AAm for acrylamide, St-S for styrenesulfonic acid, AMPS for acrylamide-2-methylpropanesulfonic acid amide, IP-S for isoprenesulfonic acid, 2-propenyl-4-nonylphenoxyethylene oxide (n = 10) The sulfonic acid ester is abbreviated as PF-S.

[0045]

Embedded image

[0046]

Embedded image

In the present invention, when the amount of the binder polymer is 1/4 to 10 times the amount of silver and the amount of silver is 2.0 g / m ² , the amount of the polymer is 0.1 g / m ² . It is preferably from 5 to ²⁰ g / m ² . More preferably 1 to 7 times the amount of half the amount per silver, if 2.0 g / m ² weight per silver is 1.0~14g / m ^2. If the amount is less than one-fourth of the amount of silver, the silver color tone is significantly degraded and may not be usable. If the amount of silver is more than ten times, the color becomes soft and may not be usable.

Although the present invention proposes the use of a ballasted compound which is less affected by moisture, in order to obtain a photothermographic material having higher performance, the compound of the present invention is incorporated in the latex particles. The method is preferred. As a method of incorporating the compound of the present invention in a latex, a compound of the present invention is dissolved in a suitable organic solvent in a latex emulsion, or a medium dispersion, ultrasonic dispersion, homogenizer dispersion, liquid-liquid facing high-speed collision method, or the like is performed to a particle size of 1 μm or less. Using a simple stirring method in which the dispersion of the fine particles is transferred to the inside of the latex by stirring and stirring, or by introducing a monomer when the compound of the present invention is converted into fine particles, radical polymerization,
A microcapsule method or the like in which addition polymerization, polycondensation, or the like is performed and confined inside can be employed.

The latex containing the ballasted phthalazine is mixed with another binder,
The water-dispersible latex may be added to the photothermographic layer, or when the water-dispersible latex is used as a binder, the latex used as the binder may be filled with ballasted phthalazine.

The mechanism for promoting the release of the phthalazine derivative by heat, which is used in the present invention, is based on the abundance and position in the layer of the additives used in the present invention, such as silver halide, organic silver salt and reducing agent. And the like can be controlled to achieve optimization.
Particularly, the compound used in the present invention that releases phthalazine by heat has a structure in which adsorption to silver halide is controlled until heated, but once heated, this control function is released. Therefore, after the heat development processing, the function of the color tone agent is developed, and the development promoting action is developed, and the color tone of the image area is improved. In the first method, the amount of the compound that releases the phthalazine derivative by heat caused in the photosensitive layer is 99.0% to 60% of the amount originally required for the color tone (the amount of the color tone agent equivalent to silver to be reduced). % And can be achieved by using a toning agent that does not ballast in one part. 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 to be imaged preferentially removes the ballast group of the phthalazine derivative It is because it operates. The photothermographic material incorporating such a mechanism improves the high-humidity temporal performance after development. The unblocked color tone is preferably 1% to 40%, but depending on the case, even if it is 1% or less, or even 40% or more, the phthalazine derivative can be adjusted by controlling the pH of the system, controlling the crosslinking density in the binder, or controlling the mobility of molecules. Can be appropriately set in the layer.

Further, the ballasted phthalazine of the present invention may be added by being contained in a wax, whereby the same effect as when it is contained in a latex as described above can be obtained. As the wax used in the present invention, a synthetic or natural wax can be widely used. In particular, carnauba wax obtained from the leaves of Brazilian palm trees is a typical example. The higher the ester content, the better, 84%
The standard is up to 85%, but it is preferable to use one having a purity of 80% or more and 100% or less.

Further, the ballasted phthalazine of the present invention may be added to a layer having voids by absorbing the particles. The particles having voids used in the present invention are preferably those having high visible transparency and capable of storing a large amount of the ballasted phthalazine of the present invention. Average particle size is 1 nm or more and 10
μm or less is preferred. The size of the void is preferably about 1/2 to 1/100 of the fine particles. As these void fine particles, commercially available ones can be used. Void silica fine particles, void styrene fine particles, zeolite fine particles, void mica fine particles, hollow calcium carbonate fine particles, α-type, β
Type, γ-type cyclodextrin, rotaxane, smectite and the like.

In order to disperse the compound of the present invention in fine particles, the compound of the present invention is dispersed in a sand mill using glass beads or zirconia fine particle media, and the solution is spouted from a thin tube at a high speed to be crushed in a hard plate shape, or from two directions. Any method may be used in which the liquid in the thin tube is made to collide and be dispersed. The fine particle dispersion preferably has a mean particle size of 1 nm or more and 10 μm or less in the aqueous solution, and preferably has a narrow particle distribution. In order to disperse in an aqueous solution, it is preferable that bubbles are not easily generated by stirring.

The use amount of the ballasted phthalazine of the present invention is preferably 1 × 10 ^-2 to 10 mol, particularly 1 × 10 ^{-2 to} 5 mol per mol of silver.

Hereinafter, other components used in the photothermographic material will be described.

The organic acid of the metal salt of the organic silver salt used in the present invention includes o-benzoylbenzoic acid, o-alkyl-substituted benzoylbenzoic acid, o-alkylbenzoic acid, m-alkylbenzoic acid, o-toluylbenzoic acid. Examples include benzoic acids such as acids, o-halogenated benzoic acids, and m-halogenated benzoic acids, and fatty acids such as acetic acid, propionic acid, stearic acid, behenic acid, and palmitic acid.

The photosensitive silver halide used in the photothermographic material of the present invention can be prepared by a method known in the field of photographic technology such as a single jet method or a double jet method, for example, by using an emulsion prepared by an ammonia method, a neutral method, or an acidic method. It can be prepared by any method such as the method. After being prepared in this way, it can be 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,
Nos. 3,713,833 and 3,748,143
No. 1,362,970, using a polymer other than gelatin such as polyvinyl acetal, and the method described in British Patent 1,354,186. Means for enzymatically decomposing gelatin in a light-sensitive silver halide emulsion, or US Pat.
As described in JP-A-76,539, various means 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, non-normal crystals such as spherical, rod-shaped, and 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 photosensitive silver halide used in the photothermographic material of the present invention can also be used in preparing an organic silver salt as described in British Patent 1,447,454. Halogen components such as ions coexist with organic silver salt-forming components, and silver ions are implanted into the components to produce organic silver salts 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. I can do things. 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-53-270.
Nos. 27 and 53-25420, each of which is described in detail below.

[0062] (1) inorganic halide: halide (wherein M represented by e.g. MX _n, H, NH _4, and represents a metal atom, n represents 1 when the M is H and NH _4, M
When is a metal atom, it represents its valence. Examples of the metal atom include lithium, sodium, potassium, cesium, magnesium, calcium, strontium, barium, zinc, cadmium, mercury, tin, antimony, chromium, manganese, iron, cobalt, nickel, rhodium, and cerium. ) And halogen molecules such as bromine water are also effective.

(2) Onium halides: quaternary ammonium halides such as, for example, trimethylphenylammonium bromide, cetylethyldimethylammonium bromide, trimethylbenzylammonium bromide, and quaternary phosphonium halides such as tetraethylphosphonium bromide And tertiary sulfonium halides such as trimethylsulfonium 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-bromo Oxazolinone, 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,
The reaction pressure is preferably set at 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 100 parts by weight, preferably 0.1 to 10 parts by weight per 1 part by weight of the organic silver salt.

The photosensitive silver halide prepared by the above-mentioned various methods includes, for example, sulfur-containing compounds, gold compounds,
Platinum compounds, palladium compounds, silver compounds, tin compounds,
Chemical sensitization can be achieved by a chromium compound or a combination thereof. The method and procedure of this chemical sensitization are described in, for example, U.S. Pat. No. 4,036,650, British Patent No. 1,518,850, JP-A-51-224.
No. 30, No. 51-78319, and No. 51-81124. Further, when a part of the organic silver salt is converted into a photosensitive silver halide by a silver halide forming component, as described in US Pat. No. 3,980,482, sensitization is achieved. A low molecular weight amide compound may coexist.

In addition, these photosensitive silver halides may have an illuminance failure, or may have an 11 to 11 group from the periodic table of the element to control 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. These metal ions may be directly introduced into silver halide as a metal salt, but can be introduced into silver halide in the form of a metal complex or complex ion. As these transfer metal complexes and metal complex ions, hexacoordinate complex ions represented by the following general formula are preferable.

In the general formula [ML ₆ ] ^m , M is a transition metal selected from the elements of Groups 6 to 11 of the periodic table, L is a bridging ligand, and m is 0, 1-, 2-, 3-. Or 4-. 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), iridium (Ir) and osmium (Os).

One of these metal complexes or complex ions may be used, or two or more of the same and different metals may be used in combination.

The content of these metal ions, metal complexes and complex ions is generally from 1 × 10 ^-9 to 1 × 10 ^-2 mol per mol of silver halide, preferably from 1 × 10 ^-9 to 1 × 10 ^-2 mol. X 10 ^-8 to 1 X 10 ^-4 mol. Compounds that provide these metal ions or complex ions are preferably added during silver halide grain formation and incorporated into silver halide grains, and preparation of silver halide grains,
That is, it may be added at any stage before and after nucleation, growth, physical ripening, and chemical sensitization, but it is particularly preferable to add at the stage of nucleation, growth, and physical ripening. It is preferably added at the stage of nucleation. In the addition, it may be added in several divided portions, may be uniformly contained in the silver halide grains, or may be added to JP-A-63-29603, JP-A-2-306236, and JP-A-2-306236. No. 167545, 4-
No. 76534, No. 6-110146, No. 5-2736
As described in JP-A-83, etc., the particles can be contained in the particles with a distribution. These metal compounds may be water or a suitable organic solvent (eg, alcohols, ethers, glycols, ketones, esters, amides).
, For example, an aqueous solution of a powder of a metal compound or a metal compound and NaCl, KCl
A method in which an aqueous solution obtained by dissolving the silver halide solution and the silver salt solution is added to a water-soluble silver salt solution or a water-soluble halide solution during grain formation, or added as a third aqueous solution when the silver salt solution and the halide solution are simultaneously mixed. A method of preparing silver halide grains by a three-liquid simultaneous mixing method, 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 metal ions or complex ions in advance when preparing silver halide. A method of adding another silver halide grain doped with and dissolving it. 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, and it is preferable to provide a matting agent on the surface of the photosensitive material in order to prevent damage to the image after thermal development. Is preferably contained in a weight ratio of 0.5 to 30% based on all binders on the photosensitive layer side.

When a non-photosensitive layer is provided on the opposite side of the photosensitive layer with the support interposed therebetween, it is preferable that at least one layer on the non-photosensitive layer side contains a matting agent, so that the slipping property of the light-sensitive material and the adhesion of fingerprints are improved. For prevention, it is preferable to provide a matting agent on the surface of the photosensitive material, and the matting agent is used in a weight ratio of 0.5 to 4 with respect to all binders in the layer on the side opposite to the photosensitive layer side.
It is preferable to contain 0%.

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. Examples of organic substances include starch described in U.S. Pat. No. 2,322,037, Belgian Patent No. 625,451 and British Patent No. 981,198.
Derivatives, polyvinyl alcohol described in JP-B-44-3643 and the like, 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 preferably has a variation coefficient of the particle size distribution of 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 These matting agents can be contained in any constituent layer, but in order to achieve the object of the present invention, it is preferable that the matting agent is supported. It is the outermost layer when viewed from the body.

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 comprises a reducible silver source (organic silver salt), a catalytically active amount of silver halide, a reducing agent, In general, the photothermographic material preferably contains a color tone agent which suppresses the color tone of silver in a state of being dispersed in an organic binder matrix. The photothermographic material of the present invention is stable at room temperature. High temperature after exposure (e.g.
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 photothermographic material of the present invention has at least one photosensitive layer on a support. Although only the photothermographic layer may be formed on the support, it is preferable to form at least one non-photosensitive layer thereon.

In order to control the amount or wavelength distribution of light passing through the photosensitive layer, a filter dye layer is formed on the same side as the photosensitive layer and / or an antihalation dye layer, so-called backing layer, is formed on the opposite side. Alternatively, the photosensitive layer may contain a dye or a pigment. Dyes and pigments that can be used in the present invention include IRG002 (Nippon Kayaku Co., Ltd.).
Or diimmonium compounds such as IRG022 (manufactured by Nippon Kayaku Co., Ltd.), bisdithiobenzylnickel complex, toluenedithiolnickel complex,
Dithiolate-based nickel complexes such as -tert-butyl-1,2-benzenedithiol nickel complex, indocyanine green (manufactured by Daiichi Pharmaceutical Co., Ltd.), NK-2014
(Manufactured by Japan Photographic Dye Laboratory), NK-2014
(Manufactured by Japan Photographic Dye Laboratories, Inc.), NK-2612
Cyanine dyes such as 1,1,5,5-tetrakis (P-dimethylaminophenyl) -3-methoxy-1,4-pentadienetoluene, NK-2772 (( Squarylium dyes, naphthoquinone dyes, phthalocyanine dyes, naphthalocyanine dyes, anthraquinone dyes, and the like. These light absorbers may be used in combination.

In the present invention, in addition to the ballasted phthalazine of the present invention, another kind of ordinary color tone agent which is not particularly ballasted or unblocked may be used. Examples of suitable toning agents to be used are Research Disclos
No. 17029, which includes the following.

Imides (for example, phthalimide); cyclic imides, pyrazolin-5-ones, and quinazolinones (for example, succinimide, 3-phenyl-2-pyrazolin-5-one, 1-phenylurazole, quinazoline and 2 , 4-thiazolidinedione); naphthalimides (e.g., N-hydroxy-1,8-naphthalimide); cobalt complexes (e.g., hexaamminetrifluoroacetate of cobalt); mercaptans (e.g., 3-mercapto-1,2,2 4-triazole); N
-(Aminomethyl) aryldicarboximides (eg, N- (dimethylaminomethyl) phthalimide);
Blocked pyrazoles (e.g., N, N'-hexamethylenebis (1-carbamoyl-3,5-dimethylpyrazole)); isothiuronium
onium) derivatives and certain photobleaches (eg, 1,8- (3,6-dioxaoctane) bis (isothiuronium trifluoroacetate) and 2-
(Combination of (tribromomethylsulfonyl) benzothiazole); phthalazinone, phthalazinone derivatives or metal salts of these derivatives (eg, 4- (1-naphthyl)
Phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxyphthalazinone, and 2,3-dihydro-1,
4-phthalazinedione); a combination of phthalazinone and a sulfinic acid derivative (for example, 6-chlorophthalazinone and sodium benzenesulfinate or 8-methylphthalazinone and sodium p-trisulfonate); a combination of phthalazine and phthalic acid; Phthalazine (including adducts of phthalazine) and maleic anhydride, and phthalic acid,
With at least one compound selected from 2,3-naphthalenedicarboxylic acid or o-phenylene acid derivatives and anhydrides thereof (for example, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic anhydride) Combinations; quinazolinediones, benzoxazines,
Naphthoxazine derivatives; benzoxazine-2,4-diones (for example, 1,3-benzoxazine-2,4-
Dione); pyrimidines and asymmetric triazines (eg, 2,4-dihydroxypyrimidine), and tetraazapentalene derivatives (eg, 3,6-dimercapto-
1,4-diphenyl-1H, 4H-2,3a, 5,6a
-Tetraazapentalene). Preferred toning agents are phthalazinone or phthalazine.

The photothermographic material of the present invention may contain an antifoggant. Mercury compounds known from, for example, U.S. Pat. No. 3,589,903 as effective antifoggants are environmentally undesirable. For this reason, non-mercury antifoggants have been studied for a long time. Non-mercury antifoggants include, for example, U.S. Pat. Nos. 4,546,075 and 4,452,885 and JP-A-59-5723.
No. 4 is preferred.

Particularly preferred non-mercury antifoggants are described in US Pat. Nos. 3,874,946 and 4,756,993.
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 JP-A-9-288328, paragraph [0030].
To [0036] are preferably used.

As another example of the preferred antifoggant, JP-A-9-90550, paragraph [006]
2] to [0063]. Further, other suitable antifoggants are disclosed in US Pat.
No. 28,523 and European Patent Nos. 600,587, 605,981 and 631,176.

The photothermographic materials of the present invention include, for example, JP-A Nos. 63-159841, 60-140335, 63-231437, 63-259651, and 6
3-304242, 63-15245, U.S. Pat. Nos. 4,639,414 and 4,740,455,
Nos. 4,741,966 and 4,751,175
No. 4,835,096. Useful sensitizing dyes for use in the invention include, for example, Research Disclosure 17643.
Section IV-A (p.23, December 1978), 18431
It is described in the literature described or cited in section X (p. 437, August 1979). 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-9-34078
And compounds described in JP-A Nos. 9-54409 and 9-80679 are preferably used.

In the present invention, a sensitizer, an organic or inorganic filler, a wax,
Surfactants, stain inhibitors, ultraviolet absorbers, antioxidants, water resistance agents, dispersants, stabilizers, plasticizers, coating aids,
Antifoaming agents, fluorescent dyes, metal salts of higher fatty acids and the like may be added.

The photothermographic layer may be composed of a plurality of layers, and the sensitivity may be made of a high-sensitivity layer / low-sensitivity layer or a low-sensitivity layer / high-sensitivity layer for adjusting the gradation. Various additives are photosensitive layer,
It may be added to any of the non-photosensitive layer and other forming layers.

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

The coating solution can be obtained as follows. A dispersion in which the ballasted phthalazine of the present invention is dispersed together with a binder; a dispersion in which an organic silver salt, silver halide and a developer are dispersed together with a binder; and a dispersion or dissolution in which necessary additives are further dispersed together with a binder. The coating liquid is obtained by mixing the liquids. When this coating solution is applied on a support and dried, a photothermographic material can be obtained.

As the coating method to be used, various methods such as a slide hopper method, a wire bar method, a roll coater method, and a vacuum extrusion method can be appropriately selected.

In the present invention, when water-based coating is performed using, for example, a latex or an aqueous solution of a binder as a binder, the water-based coating method refers to a method of preparing a coating solution.
The ratio of the organic solvent to water in the coating liquid composition is 0% or more 4
0% or less, preferably 20% or less, further 10%
Hereinafter, it means that a coating solution having a content of 5% or less is most preferably used. In applying such an aqueous coating solution, the ballasted phthalazine of the present invention significantly suppresses the fog progression reaction when the coating is stagnant as described above, thereby improving the sensitivity, fog, storage stability, etc. of the photosensitive material. it can.

In the photosensitive material of the present invention, the exposure is preferably performed by laser scanning exposure, but a laser scanning exposure machine is used in which the angle between the exposed surface of the photosensitive material and the scanning laser beam does not become substantially perpendicular. Is preferred.
Here, “not substantially vertical” means that the angle is most preferably vertical during laser scanning, preferably 55 °.
Degrees to 88 degrees, more preferably 60 degrees to 86 degrees, still more preferably 65 degrees to 84 degrees, and most preferably 70 degrees to 82 degrees. The beam spot diameter on the photosensitive material exposure surface when the laser light scans the photosensitive material is preferably 200 μm or less, more preferably 100 μm or less. It is preferable that the spot diameter is small in that the shift angle of the laser incident angle from the right angle can be reduced. The lower limit of the beam spot diameter is 1
0 μm. By performing such laser scanning exposure, it is possible to reduce image quality deterioration related to reflected light such as occurrence of interference fringe-like unevenness.

It is also preferable that the exposure in the present invention is performed using a laser scanning exposure machine which emits a scanning laser beam which is a vertical multi. As compared with the scanning laser beam in the longitudinal single mode, image quality deterioration such as generation of interference fringe-like unevenness is reduced.
To make vertical multi, use return light by combining,
A method such as applying high frequency superposition is preferred. In addition, the vertical multi means that the exposure wavelength is not single, and the distribution of the exposure wavelength is usually 5 nm or more, preferably 10 nm or more. The upper limit of the exposure wavelength distribution is not particularly limited, but is usually about 60 nm.

[0099]

EXAMPLES The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto.

Example 1 [Preparation of Subbed Photographic Support] <Preparation of PET Subbed Photographic Support> Commercially available biaxially stretched, heat-fixed, 175 μm thick, 0.170 in optical density
(Measured with a densitometer PDA-65 manufactured by Konica Corp.) 8 W / m ^{2 on} both sides of a blue colored PET film
・ A corona discharge treatment is performed for one minute, and the undercoating coating liquid a-1 shown below is applied to one surface so as to have a dry film thickness of 0.8 μm and dried to form an undercoating layer A-1. The surface was coated with the following undercoating coating solution b-1 so as to have a dry film thickness of 0.8 μm and dried to obtain an undercoating layer B-1.

<< Undercoating Coating Solution a-1 >> Butyl acrylate (30% by weight) t-butyl acrylate (20% by weight) Styrene (25% by weight) 2-hydroxyethyl acrylate (25% by weight) copolymer latex liquid (Solid content 30%) 270 g (C-1) 0.6 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 weight) ) Styrene (20% by weight) Glycidyl acrylate (40% by weight) copolymer latex liquid (solid content 30%) 270 g (C-1) 0.6 g Hexamethylene-1,6-bis (ethylene urea) 0.8 g Finish to 1 liter with water Then, on the upper surface of the undercoat layer A-1 and 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.

<< Coating Solution a-2 for Subbing Upper Layer >> Gelatin 0.4 g / m ² Weight (C-1) 0.2 g (C-2) 0.2 g (C-3) 0.1 g Silica particles ( (Average particle size: 3 μm) 0.1 g Finished to 1 liter with water << Lower upper layer coating solution b-2 >> (C-4) 60 g Latex solution containing (C-5) as a component (solid content: 20%) 80 g Ammonium sulfate 5 g (C-6) 12 g Polyethylene glycol (weight average molecular weight 600) 6 g Finish to 1 liter with water

[0103]

Embedded image

[0104]

Embedded image

(Preparation of Photosensitive Silver Halide Emulsion A) Water 9
6. Ossein gelatin having an average molecular weight of 100,000 in 00 ml
5 g and 10 mg of potassium bromide were dissolved at a temperature of 35 ° C.
After adjusting the pH to 3.0, 370 ml of an aqueous solution containing 74 g of silver nitrate and potassium bromide, potassium iodide and iridium chloride in a molar ratio of (98/2) equivalent thereto were added to 1 × 10 ^-4 per mol of silver. 370 ml of an aqueous solution containing
While maintaining the g at 7.7, the mixture was added over 10 minutes by the controlled double jet method. Then 4-hydroxy-6
-Methyl-1,3,3a, 7-tetrazaindene 0.3
g, adjust the pH to 5.0 with NaOH, average particle size 0.06 μm, coefficient of variation of particle size 12%,
[100] Cubic silver iodobromide grains having an area ratio of 87% were obtained.
This emulsion was subjected to coagulation sedimentation using a gelatin coagulant and desalting treatment, and then 0.1 g of phenoxyethanol was added thereto.
9, and adjusted to a pAg of 7.5 to obtain a photosensitive silver halide emulsion A.

(Preparation of Powdered Organic Silver Salt A) 111.4 g of behenic acid and 83.8 of arachidic acid were added to 4720 ml of pure water.
g and 54.9 g of stearic acid were dissolved at 80 ° C. Next, while stirring at a high speed, 540.2 ml of a 1.5 M aqueous sodium hydroxide solution was added, and the mixture was sufficiently stirred. Next, 6.9 ml of concentrated nitric acid was added, and the mixture was cooled to 55 ° C. to obtain a sodium organic acid solution. The temperature of the organic acid sodium solution is 55 ° C.
, And the above-mentioned silver halide emulsion (containing 0.038 mol of silver) and 450 ml of pure water were added thereto, followed by stirring for 5 minutes.
Next, 760.6 ml of a 1M silver nitrate solution was added over 2 minutes, and 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 to a predetermined concentration to finish.

(Preparation of Coating Solution for Photosensitive Layer) The following layers were sequentially formed on the undercoated support to prepare a sample. In addition, each drying was performed at 75 ° C. for 1 minute.

<Back Layer 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, manufactured by Kuraray Co., Ltd.) 2.0 g / m ² Dye C (Dye C of Example 1 of JP-A-10-161270) 70 mg / m ² Back layer protective film: 0.8 g of inert gelatin / M ² matting agent (PMMA: average particle size 3 μm) 0.02 g / m ² surfactant (N-propyloctylsulfonamidoacetic acid) 0.02 g / m ² hardening agent (1,2-bisvinylsulfonamidoethane) ) 0.02 g / m ²

[0110]

Embedded image

<Coating of Photosensitive Layer Side> A photosensitive layer was prepared by adding an aqueous dispersion of the following composition to water to prepare a coating solution. The phthalazine derivative of the present invention was added after using a sand mill disperser to form a fine particle dispersion aqueous solution having an average particle diameter of 60 nm to 150 nm (the solid content of the dispersion was 1%).
7%, and 1% of a solid content of sodium polystyrene sulfonate having a molecular weight of 500,000 was used as a dispersing aid). This coating solution is maintained at 35 ° C. and is formed from a silver electrode (purity of 99.9% or more) and a reference electrode composed of an Ag / AgCl electrode in a 3 molar solution via a salt bridge composed of a 10% KNO ₃ salt solution. After measuring the silver potential using a silver electrometer, the coating was 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.

Polyvinyl alcohol (PVA205 manufactured by Kuraray Co., Ltd.) 5.6 g / m ² Sensitizing dye A (sensitizing dye A of Example 1 of JP-A-10-161270) 2 mg / m ² Antifoggant 1 (pyridinium hydrobromide per bromide) 0.3 mg / m ² antifoggant 2 (isothiazolone) 1.2 mg / m ² antifoggant 3 (2-tribromomethylsulfonyl quinoline) 120 mg / m ² ballasted phthalazine (Table 1 Description) 360 mg / m ² developer (1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane) 3.3 mmol / m ^{2 The} photosensitive layer has a pH of 5.6. Was prepared.

[0114]

Embedded image

Surface protective layer: an aqueous solution of the following composition or
A coating solution prepared by adding the water dispersion to water was applied and dried so as to have the following amounts.

Inert gelatin 1.2 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 << Evaluation of photographic performance >> A photothermographic material was prepared as described above. At this time, a sample in which the coating solution containing the additive up to the developer was stagnated for 1 hour and a sample in which the coating solution was stagnated for 24 hours were prepared. Further, for a normal humidity test, the photothermographic material dried after applying the stagnant coating solution for 1 hour was dried at 25 ° C., 60% RH for 24 hours.
35 as a sample placed under an atmosphere of
A sample stored for 3 days in an atmosphere of 76 ° C. and 76% RH was prepared.

The stagnation test sample, the normal humidity test sample, and the high humidity test sample were each exposed with a laser sensitometer having a 780 nm semiconductor laser. At this time, the angle between the exposed surface of the photothermographic material and the exposed laser beam was 76 degrees. Next, heat development was performed at 120 ° C. for 8 seconds using a heat drum. At that time, exposure and development were performed in a room conditioned at 25 ° C. and 60% RH. The evaluation of the obtained image was performed by using a densitometer for (sensitivity, fog and maximum density Dmax), and the silver tone was visually evaluated. 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. The silver tone was evaluated relative to the darkest tone as 5 and the medium tone as 3 and a level inferior to 1. However, for the samples prepared to check the stagnation performance of the coating liquid, the difference in fog at the unexposed portion was measured, and the results are shown in Table 1 as a measure of the performance change due to stagnation.

Table 1 shows the results of the evaluation.

[0119]

[Table 1]

As described above, the use of the ballasted phthalazine of the present invention does not affect the silver tone and the developability unless the blocking group is eliminated, so that the coating liquid stagnation is more stable than the conventional one. It turns out there is. Further, a photothermographic material excellent in high humidity resistance in photographic performance such as silver tone, fog and sensitivity can be obtained.

Example 2 A photothermographic material was prepared in the same manner as in Example 1, except that the compound (2) was used as a ballasted phthalazine of the present invention in a latex as described in Table 2 during preparation of the photosensitive layer. The compound represented by was used internally. The latex was added in an amount of 4 times the weight of silver, and in order to incorporate the phthalazine derivative into the latex, ballasted phthalazine was finely dispersed to an average particle diameter of 60 nm, mixed with the latex, and stirred with a propeller at 46 ° C. for 6 hours. The ballasted phthalazine was added in an amount of 30 mmol based on silver. Also, sodium perfluorooctylsulfonate as a fluorine-based surfactant was added to the emulsion protective film and the protective film of the backing layer in an amount of 0.2 g / m ² to improve the charging characteristics and the surface slipperiness.

Table 2 shows the results. Here, as in Example 1, only the normal humidity performance and the high humidity preservability of the photothermographic material were evaluated.

[0123]

[Table 2]

From the results of Example 2, the present invention shows that the fog is low even when the ballasted phthalazine of the present invention is incorporated in a latex polymer and used under normal humidity conditions or when stored under high humidity conditions. It can be seen that a photothermographic material having excellent sensitivity can be provided, and further excellent performance can be obtained in color tone.

Example 3 A photothermographic material was prepared in the same manner as in Example 1, except that the ballasted phthalazine of the present invention was used by weight at the time of preparing a mixed coating solution of silver halide, silver behenate and developer. It was dispersed in carnauba wax 3 times and added as shown in Table 3 to prepare. After the coating solution thus prepared was allowed to stand at 35 ° C. for 1 hour and 24 hours, a light-sensitive material was prepared, and its silver tone, fog, and sensitivity were evaluated in the same manner as in Example 1.

Table 3 shows the results.

[0127]

[Table 3]

The results of Example 3 show that the photothermographic material containing the ballasted phthalazine of the present invention dispersed in wax according to the present invention has excellent silver tone even when the coating solution is stagnated for 24 hours, and has little fog increase. It can be seen that the sensitivity is high.

Example 4 Here, a light-sensitive material was prepared as in Example 1, but when adding the ballasted phthalazine of the present invention, void silica fine particles were used. Synthetic silica fine particles having an average particle diameter of 80 nm, a void of 10 nm in diameter, and a depth of 5 to 10 nm were used. 2. Ballasted phthalazine of the present invention
Three times the weight of void silica was dispersed in an aqueous solution in advance, and the ballasted phthalazine of the present invention was added thereto, followed by stirring at 35 ° C. for 6 hours.

[0130]

[Table 4]

It is understood that when the ballasted phthalazine of the present invention is used by being incorporated in fine particles having voids, the storage stability relating to silver tone is improved.

Example 5 In this example, the photothermographic materials of Examples 1 to 4 were used and the angle between the film surface and the laser beam was changed, and the laser beam was superimposed at a high frequency to obtain a vertical multi-exposure mode. Was output. The wavelength of the semiconductor laser was 810 nm, the output was 150 mW, and the development time was set at 123 ° C. for 12 seconds. As an image quality evaluation, the level of interference fringes due to laser exposure was visually evaluated. The level at which interference fringes were not visible near the density of 1.0 was set to 5 ranks, and the lowest level at which unevenness was observed with interference fringes was set to 1. The level at which there was substantially no problem even if interference fringes were visible was set to 3. The results are shown below. In the table below, the sample is indicated by connecting the example number and the sample number with a hyphen. The irradiation angle is expressed in degrees, and the multi uses a general vertical multi method. The storage conditions of the sample are the same as in Example 1.

[0133]

[Table 5]

It can be seen that the use of the photothermographic material and the exposure method of the present invention improves the level of interference fringes.

[0135]

The present invention can be applied to both aqueous coating and solvent coating, and has excellent silver color tone and excellent aging performance under high humidity.
Further, a photothermographic material having excellent coating solution stagnation during production can be obtained.

Claims (8)

[Claims] A photothermographic method comprising a photosensitive silver halide grain, an organic silver salt and a reducing agent for the organic silver salt in one or more layers on at least one surface of a support. A photothermographic material characterized in that at least one of said layer and a layer adjacent to said layer contains at least one compound which releases a phthalazine derivative which is movable in or between layers by heat. 2. A photothermographic material comprising, on at least one surface of a support, a photothermographic layer containing photosensitive silver halide grains, an organic silver salt and a reducing agent for the organic silver salt, A photothermographic material, characterized in that the photothermographic layer or a layer adjacent to the photothermographic layer contains at least one compound that releases a phthalazine derivative which is movable in or between layers by heat. 3. The photothermographic material according to claim 1, wherein a compound releasing a phthalazine derivative is present in the latex. 4. The compound according to claim 1, wherein a compound capable of releasing a phthalazine derivative is present in the wax.
2. The photothermographic material according to item 1. 5. The photothermographic material according to claim 1, wherein a compound capable of releasing a phthalazine derivative is present in fine particles having voids. 6. The photothermographic material according to claim 1, wherein the compound releasing the phthalazine derivative is present in the photothermographic material in the form of fine particles. 7. An image recording method, wherein an exposure is performed by a laser scanning exposure device in which an angle between an exposure surface of the photothermographic material according to claim 1 and a scanning laser beam is not substantially perpendicular. 8. An image recording method, comprising: exposing the exposed surface of the photothermographic material according to any one of claims 1 to 6 to a laser scanning exposing machine in which a scanning laser beam is a vertical multi-scan.