JP2003131343A - Heat developable photosensitive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat developable photosensitive material having a base coating layer which hardly causes blocking during storage, which is hardly damaged by scratching during conveyance and which has excellent adhesion property with a photosensitive layer. SOLUTION: The heat developable photosensitive material has at least one layer of a base coating layer containing a matting agent and a polymer latex having the primary particle size smaller than the particle size of the matting agent between a photosensitive layer and a supporting body. In the base coating layers, the amount of the polymer latex L (mg/m<2> ) in the layer farthest from the supporting body, the film thickness D (μm) of that layer and the whole amount of the matting agent M (mg/m<2> ) in the base coating layers satisfy both of formula (1): -9.19×L-34.5×M+3920×D>180 and formula (2): -27.9×L+36.7×M+6026×D<200.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a photothermographic material which forms an image by heat development.

[0002]

2. Description of the Related Art Conventionally, in the fields of medical treatment and printing plate making, a waste liquid caused by a wet process of an image forming material has been a problem in terms of workability. Weight loss is strongly desired. Therefore, there is a need for a technology related to photothermographic materials for photographic technology, which enables efficient exposure by a laser imager or a laser imagesetter and can form a clear black image with high resolution. As such a technology, for example,
U.S. Pat. Nos. 3,152,904 and 3,487,07
No. 5, and D.I. "Dry Silver Photographic Material" by Morgan
”Graphic Materials” (Hand
book of Imaging Material
s, Marcel Dekker, Inc. Page 48,
1991) and the like, a photothermographic material containing an organic silver salt, a photosensitive silver halide grain, and a reducing agent on a support is known. Since this heat-developable photosensitive material does not use any solution processing chemicals, it is possible to provide the user with a simpler system that does not damage the environment.

The design of these photothermographic materials requires special considerations specific to photothermographic development, which are different from the photothermographic materials developed by conventional developing solutions. Especially during heat development, usually 80 to 1
Since heat of 40 ° C is applied, a design different from the conventional one is required. For example, a photothermographic material has a photosensitive layer for forming an image and a backing layer containing a dye for absorbing a laser beam from an imager on a support. It must be firmly adhered to the support not only before development but also after heat development. In order to adhere these layers to the support, an undercoat layer having an easily adhering function is often provided on the support. It is generally known that an easy-adhesion layer for the purpose of adhering to the photosensitive layer is likely to soften near the heat development temperature, and if a material having a high compatibility with the upper layer component is used, the adhesion after heat development is good. Has been. However, in order to maintain the adhesive strength even at room temperature during storage or when heat is applied during development, the undercoat layer must be designed so that it can exhibit sufficient functions in a wide temperature range. Of course, in general, a material having high heat resistance must be used for the undercoat layer.

By the way, these photothermographic materials, like conventional photographic materials, are manufactured by a method of transporting a long and wide film, repeating coating and drying of each layer, and finally winding it into a roll. To be done. Since the wound film is stored in a roll form until the work of the next step, the films may stick to each other due to the temperature at the time of storage and the pressure due to its own weight. In addition, the films may rub against each other during contact with the roll during transport or during winding / unwinding, and the outermost surface of the film may be damaged. In order to prevent sticking and scratches, it is effective to provide a matting agent on the film surface. Therefore, it is not special to provide the undercoat layer, which is not actually treated as a product, with a matting agent in order to prevent problems during manufacturing.

As described above, the undercoat layer for a photothermographic material does not have all the functions of adhesiveness before and after thermal development, adhesiveness during storage, sticking resistance during production and scratch resistance. However, the design of the undercoat layer requires a study beyond the conventional wisdom of wet process photographic undercoat layers.

[0006]

The present invention has been made in view of the above circumstances, and an object thereof is to prevent blocking during storage, scratches during transportation, and a photosensitive layer containing an organic silver salt. The present invention provides a photothermographic material having an undercoat layer having excellent adhesiveness.

[0007]

The above problems in the present invention are solved by the following constitutions.

1. In a photothermographic material having a photosensitive silver halide, a non-photosensitive organic silver salt, and a photosensitive layer containing a reducing agent for the organic silver salt on at least one surface of the support, the support and the photosensitive layer Between them, at least one undercoat layer containing a matting agent and a polymer latex having a primary particle size smaller than the particle size of the matting agent, and the amount of the polymer latex in the layer farthest from the support of the undercoating layer. L (mg
/ M ² ), the film thickness D (μm) of the layer, and the total amount M (mg / m ² ) of the matting agent in the undercoat layer simultaneously satisfy the above (formula 1) and (formula 2). And a photothermographic material.

2. In a photothermographic material having a photosensitive silver halide, a non-photosensitive organic silver salt, and a photosensitive layer containing a reducing agent for the organic silver salt on at least one surface of the support, the support and the photosensitive layer And an undercoat layer containing a matting agent, a polymer latex having a primary particle size smaller than the particle size of the matting agent, and a water-soluble polymer, and the burial depth of the matting agent in the undercoating layer is Matting agent particle size of 10-6
A photothermographic material characterized by being 0%.

3. In a photothermographic material having a photosensitive silver halide, a non-photosensitive organic silver salt, and a photosensitive layer containing a reducing agent for the organic silver salt on at least one surface of the support, the support and the photosensitive layer A matting agent, an undercoat layer containing a polymer latex having a primary particle size smaller than the particle size of the matting agent, and a water-soluble polymer, and the matting agent per cm ^{2 on the} surface of the undercoat layer. Is 2
A photothermographic material, characterized in that the number is from 0,000 to 800,000.

4. In a photothermographic material having a photosensitive silver halide, a non-photosensitive organic silver salt, and a photosensitive layer containing a reducing agent for the organic silver salt on at least one surface of the support, the support and the photosensitive layer And an undercoat layer containing a matting agent and a polymer latex having a primary particle size smaller than that of the matting agent, the matting agent having a cross-linking group which reacts with the polymer latex or the water-soluble polymer on the surface. A photothermographic material having:

5. In a photothermographic material having a photosensitive silver halide, a non-photosensitive organic silver salt, and a photosensitive layer containing a reducing agent for the organic silver salt on at least one surface of the support, the support and the photosensitive layer A plurality of subbing layers between the subbing layers, a layer different from the layer furthest from the support in the subbing layer contains a matting agent, and the subbing layer furthest away from the support is It contains a polymer latex having a primary particle size smaller than the particle size of the matting agent and a water-soluble polymer, and the total film thickness of all undercoat layers is 1 of the average particle size of the matting agent.
A photothermographic material which is larger than / 5 and smaller than 4/5.

6. 6. The photothermographic material according to any one of 1 to 5, wherein the water-soluble polymer is a water-soluble polymer containing polyvinyl alcohol as a main component.

7. 6. The photothermographic material according to any one of 1 to 5, wherein the water-soluble polymer is a water-soluble polymer containing a water-soluble polyester as a main component.

Under the background as described above, the inventors of the present invention maintain the mechanical film strength around room temperature, that is, soften at a high temperature, while maintaining the adhesion with the upper layer whose state changes before and after the heat development treatment. In addition, the present invention has been completed by finding that it is necessary to design a function and a material to achieve sufficient adhesiveness and strength at room temperature, even though the material is compatible with the upper layer.

The present invention will be described below. First, the characteristic part of the present invention will be described. Since the photothermographic material of the invention has the following constitution in the undercoat layer, it is less likely to cause blocking during storage, is less likely to be scratched during transportation, and has excellent adhesiveness to the photosensitive layer. is there.

First, the undercoat layer contains a matting agent and a polymer latex having a primary particle size smaller than the particle size of the matting agent, and is the layer farthest from the support of the undercoating layer (also called the undercoating outermost layer). The amount of polymer latex L (mg / m ² ),
The film thickness D (μm) of the layer and the total amount M of the matting agent in the undercoat layer
(Mg / m ² ) simultaneously satisfies the following (formula 1) and (formula 2). (Formula 1) −9.19 × L-34.5 × M + 3920 × D> 180 (Formula 2) −27.9 × L + 36.7 × M + 6026 × D <200 This subbing layer is a layer immediately below the photosensitive layer. It contains a water-soluble polymer that is stable in a wide temperature range from room temperature to near the heat development temperature, a polymer latex that is highly compatible with the photosensitive layer near the heat development temperature, and a matting agent. If the polymer latex amount L is too large, the adhesiveness with the photosensitive layer before and after heat development is improved, but the mechanical strength as the undercoat layer is insufficient, and problems such as scratches occur during transportation and storage.

By controlling the particle size of the polymer latex used here and the film thickness D of the undercoat outermost layer to predetermined values,
A structure in which the polymer latex particles protrude from the undercoat layer can be imparted to the surface of the undercoat layer. Such a structure is an advantageous structure for the undercoat layer immediately below the photosensitive layer, which can obtain a sufficient adhesive force with a minimum addition amount of the polymer latex. In addition to the minimum amount L of polymer latex and the film thickness D required for adhesion, and further setting the amount M of the matting agent to a specified amount, the film strength of the undercoat layer is increased, and scratches during transport can be reduced. By satisfying the values of L, M, and D at the same time with (Equation 1) and (Equation 2), the above-mentioned problems are improved, and the undercoating having a structure and physical properties sufficiently exerting the effect of the present invention is obtained. A layer is obtained.

The undercoat layer contains a matting agent, a polymer latex having a primary particle size smaller than the particle size of the matting agent, and a water-soluble polymer. The composition is 10 to 60% of the particle diameter of the matting agent.

The matting agent in the undercoat layer is uniformly contained on the surface of the undercoat layer so as to protrude from the surface of the undercoat layer in order to prevent sticking (blocking) and scratches. When the protrusion height of the matting agent is such that the burying depth of the matting agent is 10 to 60% of the average particle diameter of the matting agent, the undercoat layer in which the effect of the present invention is sufficiently exhibited can be obtained. Burial depth is 1
If it is less than 0%, it may cause the mat to fall off, and if the burial depth exceeds 60%, the blocking prevention effect is reduced.

The undercoat layer contains a matting agent, a polymer latex having a primary particle size smaller than the particle size of the matting agent, and a water-soluble polymer.
The number of matting agents per m ² is 200,000 or more and 800,000 or less.

The matting agent in the undercoat layer is uniformly contained on the surface of the undercoat layer in a mixed system with a polymer latex containing a water-soluble polymer as a main component. Problems such as scratches are caused by contact with rolls during transport, contact between films during winding and unwinding, and misalignment. The matting agent protruding from the surface of the undercoat layer comes into contact with the roll or the film, and the matting agent embedded in the surface of the undercoat layer slides down while destroying the undercoat layer (matting off), causing scratches on the film surface. Traces remain. In order to prevent scratches from becoming a problem, it is better to reduce the number of matting agents that are the starting points of fracture.

In the present invention, from the viewpoint of exerting its effect, the number of matting agents per cm ² is 200,000 or more and 8 or more.
Optimally, it is less than or equal to 0,000, and favorable results are obtained. If the number of matting agents is too large, the matte will fall off and scratches will be generated, and if it is too small, the matting effect on the film surface will be reduced and sticking (blocking) will occur when rolled into a roll, which is not preferable. Here, the number of matting agents is determined from the electron micrograph of the undercoat layer surface to the undercoat layer surface 1
The value roughly calculated on the assumption that it is uniformly distributed over cm ² is used.

The undercoat layer contains a matting agent and a polymer latex having a primary particle size smaller than the particle size of the matting agent, and the matting agent has a cross-linking group which reacts with the polymer latex or the water-soluble polymer on the surface. Adopt a configuration that has.

The scratch, which is a problem in the present invention, occurs when the matting agent falls off. Therefore, in the undercoat layer, it is preferable to increase the chemical bonding force between the matting agent and the undercoat layer by using the below-described surface-modified matting agent to make it difficult for the mat to fall off.

The subbing layer is composed of a plurality of subbing layers, contains a matting agent in a layer different from the subbing outermost layer, and has a particle size smaller than the particle size of the matting agent in the subbing outermost layer. A composition containing a polymer latex having a secondary particle size and a water-soluble polymer and having a total thickness of all subbing layers larger than 1/5 of the average particle diameter of the matting agent and smaller than 4/5 is adopted. . As a method for preventing the slipping of the matting agent, there is a method in which a matting agent is contained in a layer lower than the undercoating outermost layer, and the undercoating outermost layer is coated so that the matting agent protrudes from the layer. . Containing the matting agent in a layer different from the subbing outermost layer has an effect of dispersing stress when an impact is applied to the matting agent, which is an object of the present invention, not only to prevent scratches but also to prevent blocking. Also exerts a sufficient effect. In that case, the thickness of the entire undercoat layer is 4/5 of the average particle diameter of the matting agent.
When it is smaller than the above, the matting agent may be present in any layer as long as it is a layer below the undercoating outermost layer. At this time, the subbing outermost layer is preferably a layer containing a water-soluble polymer and a polymer latex in terms of mechanical strength and adhesion to the photosensitive layer.

With respect to this effect, the effect of stress dispersion is not impaired even when used in combination with the matting agent contained in the outermost surface layer of the undercoat layer, that is, by containing the matting agent in two or more different layers.

In the present invention, when the undercoat layer has the above-mentioned structure, blocking is less likely to occur during storage of the photothermographic material, scratches are less likely to occur during transportation, and adhesion to the photosensitive layer is excellent. A photothermographic material having a coating layer is obtained.

Next, each material used for the undercoat layer will be described. (Polymer Latex) The polymer latex in the present invention refers to a polymer composed of a copolymer and dispersible in an aqueous solvent, and examples thereof include an acrylic type, a styrene-diolefin copolymer type, a vinylidene chloride type, and a polyurethane type. The average particle size of the polymer latex particles in the invention is preferably 0.005 to 0.4 μm, more preferably 0.01 to 0.25 μm. The particle size distribution of the dispersed particles is not particularly limited, and may be a wide particle size distribution or a monodisperse particle size distribution.

The polymer latex used in the present invention may be a so-called core / shell type latex in addition to the usual polymer latex having a uniform structure. In this case, it may be preferable that the core and the shell have different glass transition temperatures. The glass transition temperature of this polymer latex is preferably higher than room temperature and lower than the heat development treatment temperature, specifically between 40 ° C. and 110 ° C., particularly preferably 50 ° C. to 80 ° C. Is.

The polymer latex used in the present invention can be produced by an emulsion polymerization method. For example, using water as a dispersion medium, a monomer of 10 to 50 mass% with respect to water and a polymerization initiator of 0.05 to 5 mass% with respect to the monomer,
About 30 to 100 with 0.1 to 20% by weight of dispersant
C., preferably 60 to 90.degree. C., and polymerized under stirring for 3 to 8 hours. The conditions such as the amount of monomer, the amount of polymerization initiator, the reaction temperature and the reaction time can be widely changed.

As the polymerization initiator, a water-soluble peroxide (eg, potassium persulfate, ammonium persulfate, etc.), a water-soluble azo compound (eg, 2,2′-azobis (2-aminodipropane) hydrochloride, etc.) Alternatively, a redox polymerization initiator or the like in which a reducing agent such as Fe ²⁺ salt or sodium hydrogen sulfite is combined can be used.

A water-soluble polymer is used as the dispersant, and an anionic surfactant, a nonionic surfactant,
Both a cationic surfactant and an amphoteric surfactant can be used.

The polymer latex used in the present invention is used alone from the monomer group described below, or as a mixture of a plurality of other monomers such as other second and third monomers copolymerizable with the first monomer. Can be manufactured.

Examples of acrylic monomers include acrylic acid; methacrylic acid; acrylic acid esters such as alkyl acrylates (eg, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-). Butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, phenylethyl acrylate, etc.), hydroxy-containing alkyl acrylate (eg, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, etc.); methacrylic acid ester, eg, alkyl Methacrylate (eg, methyl methacrylate, ethyl methacrylate, n-propyl meta Relate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, phenylethyl methacrylate, etc., hydroxy-containing alkyl methacrylate (for example, 2-hydroxyethyl methacrylate) , 2-hydroxypropyl methacrylate, etc.); acrylamide; substituted acrylamides such as N-methyl acrylamide, N-methylol acrylamide, N, N-dimethylol acrylamide, N-
Methoxymethylacrylamide, etc .; Methacrylamide;
Substituted methacrylamide, such as N-methyl methacrylamide, N-methylol methacrylamide, N, N-dimethylol methacrylamide, N-methoxymethyl methacrylamide, etc .; Amino group substituted alkyl acrylate, such as N, N-diethylaminoethyl acrylate; amino Group-substituted alkyl methacrylates such as N, N-diethylaminomethacrylate; epoxy group-containing acrylates such as glycidyl acrylate; epoxy group-containing methacrylates such as glycidyl methacrylate; salts of acrylic acid such as sodium salts, potassium salts, ammonium salts; salts of methacrylic acid. , For example, sodium salt, potassium salt, ammonium salt. The above-mentioned monomers can be used in combination with the following comonomers.

Examples of comonomers capable of reacting with acrylic monomers include styrene and its derivatives; unsaturated dicarboxylic acids (eg itaconic acid, maleic acid, fumaric acid); esters of unsaturated dicarboxylic acids (eg methyl itaconate, Dimethyl itaconate, methyl maleate, dimethyl maleate, methyl fumarate, dimethyl fumarate); salts of unsaturated dicarboxylic acids (eg sodium salts, potassium salts, ammonium salts); sulfonic acid groups or salts thereof Monomers (for example, styrene sulfonic acid, vinyl sulfonic acid) and salts thereof (sodium salt, potassium salt, ammonium salt); acid anhydrides such as maleic anhydride and itaconic anhydride; vinyl isocyanate; allyl isocyanate; vinyl methyl ether;
Vinyl ethyl ether; acrylonitrile; vinylidene chloride; vinyl chloride; vinyl acetate. The above-mentioned monomers can be used alone or in combination of two or more.

Examples of the styrene-based monomer include styrene and styrene derivatives, such as methylstyrene, dimethylstyrene, ethylstyrene, diethylstyrene,
Isopropylstyrene, butylstyrene, hexylstyrene, cyclohexylstyrene, decylstyrene, benzylstyrene, chloromethylstyrene, trifluoromethylstyrene, ethoxymethylstyrene, acetoxymethylstyrene, methoxystyrene, 4-methoxy-3-.
Methylstyrene, dimethoxystyrene, chlorostyrene, dichlorostyrene, trichlorostyrene, tetrachlorostyrene, trichlorostyrene, tetrachlorostyrene, pentachlorostyrene, bromostyrene, dibromostyrene, iodostyrene, fluorostyrene, trifluorostyrene, 2- Brom-4-trifluoromethylstyrene, 4-fluoro-3-trifluoromethylstyrene, vinylbenzoic acid, vinylbenzoic acid methyl ester, divinylbenzene and the like can be mentioned, but styrene is preferred. Here, the substitution position of the styrene derivative for an alkyl group, an alkoxy group, and a halogen atom for ground ventilation is any one of o, m, and p.

As the diolefin-based monomer, conjugated dienes such as butadiene, isoprene and chloroprene, and non-conjugated dienes such as 1,4-pentadiene, 1,4-hexadiene, 3-vinyl-1,5-hexadiene, 1,
5-hexadiene, 3-methyl-1,5-hexadiene, 3,4-dimethyl-1,5-hexadiene, 1,2
-Divinylcyclobutane, 1,6-heptadiene, 3,
5-diethyl-1,5-heptadiene, 4-cyclohexyl-1,6-heptadiene, 3- (4-pentenyl)
-1-cyclopentene, 1,7-octadiene, 1,8
-Nonadiene, 1,9-decadiene, 1,9-octadecadiene, 1-cis-9-cis-1,2-octadecatriene, 1,10-undecadiene, 1,11-dodecadiene, 1,12-tridecadiene , 1,13-tetradecanediene, 1,14-pentadecadiene, 1,15
-Hexadecadiene, 1,17-octadecadiene,
1,21-docosadiene, cyclohexanediene, cyclobutanediene, cyclopentadiene, cycloheptadiene and the like can be mentioned, but butadiene, isoprene and chloroprene are preferable, and butadiene is particularly preferable.

As the polyurethane type, commercially available water-based polyurethanes shown below or JP-A-55-15825,
As described in JP-A-56-106860,
(1) a dihydroxy compound having a molecular weight of 750 to 3000,
(2) Polyisocyanate, (3) Water-soluble group of aliphatic aminocarboxylic acid or sulfonic acid having at least one hydrogen atom bonded to nitrogen, and (4) Isocyanate group as chain extender An emulsifier-free aqueous polyurethane dispersion in which two reactive hydrogen atoms and a salt-free compound having a molecular weight of 300 or less are dissolved or dispersed in an aqueous organic solvent to cause a reaction, and finally the organic solvent portion is removed. A liquid is included.

As an example of the commercially available water-based polyurethane, Takerak XW series W-700 manufactured by Takeda Pharmaceutical Co., Ltd.
4, W-6015, W-621, W-511, W-31
0, W-512, Bayer Implanil (impr
anil) DLH and Implanil DLN, Daiichi Kogyo Seiyaku Co., Ltd. Superflex 100, Superflex 200, Superflex 300, Hydran HW
-140, Hydran HW-111, Hydran HW-
100, Hydran HW-101, Hydran HW-3
12, Hydran HW-311, Hydran HW-31
0, Hydran LW-513, Hydran HC-20
0, Hydran HC-400M, Bondic 1010
C, Bondic 1050, Bondic 1070, Bondic 1310B, Bondic 1310F, Bondic 1310NS, Bondic 1340, Bondic 1510, Bondic 1610NS, Bondic 1630, Bondic 1640, Bondic 1
670 (N), Bondic 1670-40 and the like. Among these commercially available aqueous polyurethanes, W-7004 and W-601 are particularly preferable products.
5, Implanil DLH, Implanil DLN, Superflex 100, Superflex 200, Hydran HW-312, Hydran HW-140, Hydran HW-310, Hydran HW-311 and the like can be mentioned. (Water-Soluble Polymer) The water-soluble polymer used in the present invention may be either a natural product or a synthetic polymer, and is not limited. Oxide,
A water-soluble polymer having many functional groups or structural units having high affinity with water, such as carboxylic acid, sulfonic acid, and metal salts thereof, is preferable.

Examples of natural products include starches, polysaccharides, proteins and their derivatives, semi-synthetic polymers include viscose, cellulose, polyamides and their derivatives, and synthetic polymers such as polyvinyl alcohol and polyacrylamide. , Polyvinylpyrrolidone, polyalkylene glycol, polyvinyl ether, polystyrene sulfonic acid, and poly (meth) copolymer thereof. From the viewpoint of heat resistance, mechanical strength and photographic performance, a particularly preferred water-soluble polymer is preferably a polymer containing polyvinyl alcohol as a main component or a polymer containing water-soluble polyester as a main component.

Examples of the polymer containing vinyl alcohol as a main component include polyvinyl alcohol derivatives, copolymerized polyvinyl alcohol, modified compounds having a polyvinyl alcohol unit dissolved in water by partial formalization, acetalization, butyralization, and the like. You can

Polyvinyl alcohol has a degree of polymerization of 1
00 or more is preferable. Examples of the modified compound containing a vinyl alcohol unit include vinyl compounds such as ethylene and propylene, acrylic acid esters (t-butyl acrylate, phenyl acrylate and 2- Naphthyl acrylate, etc., Methacrylic acid esters (methyl methacrylate, ethyl methacrylate, 2-hydroxyethyl methacrylate, benzyl methacrylate, 2-hydroxypropyl methacrylate, phenyl methacrylate, cyclohexyl methacrylate, cresyl methacrylate, 4-chlorobenzyl methacrylate, ethylene glycol di) Methacrylate, etc., acrylamides (acrylamide, methyl acrylamide, ethyl acrylamide, propyl acrylamide, Acrylamide, tert-butyl acrylamide, cyclohexyl acrylamide, benzyl acrylamide, hydroxymethyl acrylamide, methoxyethyl acrylamide, dimethylaminoethyl acrylamide, phenyl acrylamide, dimethyl acrylamide, diethyl acrylamide, β-cyanoethyl acrylamide, diacetone acrylamide, etc.), methacrylamides (Methacrylamide, methylmethacrylamide, ethylmethacrylamide, propylmethacrylamide, butylmethacrylamide, tert-butylmethacrylamide, cyclohexylmethacrylamide, benzylmethacrylamide, hydroxymethylmethacrylamide, methoxyethylmethacrylamide, dimethylaminoethylmethacrylamide. , Phenylmethacrylamide, dimethylmethacrylamide, diethylmethacrylamide, β-cyanoethylmethacrylamide, etc.), styrenes (styrene, methylstyrene, dimethylstyrene, trimethylenestyrene, ethylstyrene, isopropylstyrene, chlorostyrene, methoxystyrene, acetoxystyrene) , Chlorostyrene, dichlorostyrene, bromstyrene, vinylbenzoic acid methyl ester, etc.), divinylbenzene, acrylonitrile, methacrylonitrile, N-vinylpyrrolidone, N-vinyloxazolidone, vinylidene chloride, phenyl vinyl ketone, etc. Mention may be made of polymers. Among these, ethylene copolymer polyvinyl alcohol is preferable.

The polymer whose main component is a water-soluble polyester is a substantially linear polyester obtained by polycondensation reaction of dibasic acid or its ester-forming derivative with glycol or its ester-forming derivative. , A component having a water-soluble group because it is more water-soluble, for example,
A polyester in which a component having a sulfonate, a diethylene glycol component, a polyalkylene glycol component, a polyalkylene glycol dicarboxylic acid component and the like are introduced as a copolymerization component in the polyester. As the component having a water-soluble group, an aromatic dicarboxylic acid having a sulfonate is preferable.

Examples of the dibasic acid component of the water-soluble polyester include terephthalic acid, isophthalic acid, phthalic acid,
Phthalic anhydride, 2,6-naphthalenedicarboxylic acid, 1,
5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-
Cyclohexanedicarboxylic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid, itaconic acid and the like can be used. The dicarboxylic acid having a sulfonate is particularly preferably one having a group of an alkali metal sulfonate, such as 4-sulfoisophthalic acid, 5-sulfoisophthalic acid, sulfoterephthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-
2,7-dicarboxylic acid, 5- (4-sulfophenoxy)
Examples thereof include alkali metal salts such as isophthalic acid, and among them, 5-sulfoisophthalic acid sodium salt is particularly preferable.

Examples of the glycol component include ethylene glycol, diethylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, dipropylene glycol, 1,6-hexanediol and 1,4-cyclohexanediene. methanol,
Examples thereof include xylylene glycol, polyethylene glycol (polyethylene oxide glycol), and polytetramethylene oxide glycol.

As the water-soluble polyester useful in the present invention, a water-soluble polyester modified with a vinyl polymer can be more preferably used. The water-soluble polyester modified with a vinyl-based polymer is a water-soluble polyester prepared by dissolving a water-soluble dispersion of a vinyl-based monomer in an aqueous solution of the water-soluble polyester, or a vinyl-based monomer in an aqueous solution of the water-soluble polyester. It can be obtained by dispersing and carrying out emulsion polymerization or suspension polymerization. The polymerization is preferably emulsion polymerization. The structure of the resulting modified water-soluble polyester is not known, but the inventor believes that the vinyl monomer in the water-soluble polyester solution may have a structure grafted (branched) to the water-soluble polyester during polymerization. .

Examples of vinyl monomers include (meth) acrylic monomers, hydroxy group-containing (meth) acrylic monomers such as 2-hydroxypropyl acrylate, amide group-containing (meth) acrylic monomers such as (meth) acrylamide, and glycidyl (meth). ) Epoxy group-containing (meth) acrylic monomers such as acrylate, acrylic acid, methacrylic acid and salts thereof (sodium salt, potassium salt,
Examples thereof include a monomer containing a carboxyl group such as ammonium salt) or a salt thereof. Further, as the monomer other than the acrylic monomer, for example, styrenesulfonic acid, vinylsulfonic acid and salts thereof (sodium salt,
Monomers containing sulfonic acid groups such as potassium salts and ammonium salts) or salts thereof, crotonic acid, itaconic acid,
Monomers containing carboxyl groups or salts thereof such as maleic acid, fumaric acid and salts thereof (sodium salt, potassium salt, ammonium salt, etc.), acid anhydride monomers such as maleic anhydride, itaconic anhydride, vinyl isocyanate, allyl Isocyanate, styrene, vinyltrisalkoxysilane, alkyl maleic acid monoester,
Alkyl fumaric acid monoester, acrylonitrile,
Methacrylonitrile, alkyl itaconic acid monoester, vinylidene chloride, vinyl acetate, vinyl chloride and the like can be mentioned. Of these, acrylic modified water-soluble polyester is preferable. (Matting Agent) The matting agent useful in the present invention may be inorganic fine particles or organic polymer fine particles, but it is preferable that the matting agent does not deform when heat-developed at 80 to 140 ° C.

As the matting agent for inorganic fine particles useful in the present invention, those having a structure of an inorganic compound described in Chemistry Encyclopedia 9 (Kyoritsu Shuppan), page 312 (Showa 43 reduced edition, 4th edition) are used. However, for example, the inorganic fine particles include CaCO ₃ , CaSO ₄ , ZnS, BaSO ₄ , and Mg.
CO ₃ , CaF ₂ , ZnO, ZnCO ₃ , TiO ₂ , SnO
₂ , SiO ₂ , Al ₂ O _{3 and the} like can be mentioned, and a composite metal compound thereof may be used. For example, SiO ₂ hydrolyzes ethyl orthosilicate (Si (OC ₂ H ₅ ) ₄ ) to form hydrous silica (Si (OH) ₄ ), and further forms hydrous silica monodisperse spheres. A silica matting agent can be prepared by forming a silica bond into a three-dimensionally grown product by dehydration treatment.
Among them, in the present invention, a matting agent made of silica is particularly preferable.

Further, a matting agent whose surface is modified with an alkoxide is more preferable. The matting agent whose surface is modified with an alkoxide is a drying step after synthesis in water and alcohol and / or after being interrupted when the particle size which is a synthesis process is reached, for example, after forming at a high temperature of about 300 ° C. Alcohol remains on the surface of the matting agent. For example, as a commercially available matting agent, Seahoster KE-P5
0, the same KE-P20, the same KE-P30, the same KE-40,
Same KE-50, Same KE-P70, Same KE-80, Same KE
-90, KE-P100, KE-P150 (all manufactured by Nippon Shokubai Co., Ltd.) and the like. See also KE
-E20, KE-E30, KE-E40, KE-
E50, KE-E70, KE-E80, KE-E
90, KE-E150, etc. (all manufactured by Nippon Shokubai Co., Ltd.)
Can also be mentioned. Examples of the alcohol include methanol, ethanol, propanol, butanol, amyl alcohol, benzyl alcohol, ethylene glycol and the like. Among them, methanol and ethanol are preferable, and methanol is more preferable.

The organic polymer fine particle matting agent useful in the present invention can be used without particular limitation as long as it is heat-resistant, highly elastic, hard to aggregate and hard to break. It is an organic polymer fine particle having on its surface a crosslinking group that reacts with the polymer latex or the water-soluble polymer in the undercoat layer. The organic polymer fine particles having a cross-linking group on the surface are mainly composed of a resin having a relatively high glass transition point, and have a surface having a plurality of polymerization-reactive groups such as vinyl groups, hydroxyl groups, epoxy groups, or isocyanate groups. , Fine particles having a relatively active functional group such as an active methylene group. Examples of the monomer used as the main component include acrylic acid esters, methacrylic acid esters, vinyl esters, acrylamides, methacrylamides, styrenes, divinylbenzene, acrylonitrile, methacrylonitrile, N-vinylpyrrolidone, N- Examples thereof include vinyl oxazolidone, vinylidene chloride, phenyl vinyl ketone and the like. Examples of the monomer having an active reactive group include ethylene glycol dimethacrylate, trimethylolpropane triacrylate, 1,4-butanediol diacrylate and 1,6-
Hexanediol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, glycerol dimethacrylate, glycerol diacrylate, glycerol acloxydimethacrylate, divinylbenzene, cyclopentadiene, Triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, diallyl terephthalate, diallyl phthalate, hydroxyethyl methacrylate, hydroxyethyl acrylate,
Examples thereof include dihydroxyethyl acrylate, dihydroxyethyl methacrylate and glycidyl methacrylate.

The matting agent useful in the present invention preferably has a more spherical shape. Ratio r of short diameter r1 and long diameter r2 of matting agent
It is preferable that 2 / r1 is in the range of 1 to 1.4 and the average particle size is 0.01 to 1.6 μm. More preferably, the ratio r2 / r1 is 1 to 1.25 and the average particle size is 0.1.
It is 0.7 μm. The ratio r2 / r1 in the present invention is obtained by drawing an inscribed circle having a minimum diameter and a circumscribing circle having a maximum diameter from an image obtained by enlarging matting agent particles to about tens of thousands of times with an electron microscope.
The diameter r1 of the inscribed circle and the diameter r2 of the circumscribed circle are measured and obtained. The average particle size in the present invention can be known by taking an electron micrograph of the matting agent and measuring the particle size of 500 matting agent particles. By using the matting agent having such a shape and average particle diameter, unlike the conventional matting agent, the matting agent does not abnormally project from the undercoat layer, and it is less likely to be scratched or come off.

Next, a technique common to the present invention will be described. A publicly known technique can be basically adopted as the common technique.

Materials for the support (hereinafter referred to as the support according to the present invention) which can be used in the photothermographic material of the present invention include various polymer materials, glass, wool cloth, cotton cloth,
Examples of the material include paper and a metal such as aluminum, but a material that can be processed into a flexible sheet or roll is preferable. Plastic film (eg cellulose acetate film, polyester film, polyethylene terephthalate film, polyethylene naphthalate film, polyamide film, polyimide film, cellulose triacetate film or polycarbonate film)
Is used.

When the photothermographic material of the present invention is used for medical purposes, the support of the present invention is preferably a blue-colored biaxially stretched heat-fixed polyethylene terephthalate film having a thickness of 70 to 180 μm. As another example, paragraph No. “0030” of JP 2001-22026 A
The techniques described in “0034” and the like can be used in the present invention. The support according to the present invention is preferably subjected to corona discharge treatment. The condition of the discharge amount is 5 to 30 W / m
² minutes is preferred. The undercoat layer according to the present invention is preferably applied to the corona-treated support within 1 to 2 months after the corona treatment.

The support according to the present invention may be subjected to plasma surface treatment. Particularly, plasma treatment near atmospheric pressure is preferable. As a processing gas for performing plasma discharge, a gas capable of imparting a polar functional group such as an amino group, a carboxyl group, a hydroxyl group, and a carbonyl group is preferable, and examples thereof include nitrogen (N ₂ ) gas, hydrogen (H ₂ ) gas, and oxygen. There are (O ₂ ) gas, carbon dioxide (CO ₂ ) gas, ammonia (NH ₃ ) gas, water vapor and the like. In addition to the reaction gas, an inert gas such as helium or argon is required, and the gas mixing ratio is 60
A stable discharge condition can be obtained when the content is at least%. However, when the plasma is generated by the pulsed electric field, the inert gas is not always necessary and the concentration of the reaction gas can be increased. Frequency of pulsed electric field 1-100
The kHz range is preferred. The time for which one pulsed electric field is applied is preferably 1 to 1000 μs, and the magnitude of the voltage applied to the electrodes is 1 to 100 kV /
The range of cm is preferable.

The organic silver salt that can be used in the photothermographic material of the present invention is a reducible silver source, and is a silver salt of an organic acid or a heteroorganic acid, particularly a long-chain (having 10 to 30 carbon atoms, preferably carbon atoms). 15-25) Silver salts of aliphatic carboxylic acids and nitrogen-containing heterocyclic compounds are preferred. Organic or inorganic complexes described in Research Disclosure 17029, 29963, in which the ligand has a total stability constant with respect to silver ions of 4.0 to 10.0, are also preferred. Examples of these suitable silver salts include silver salts of organic acids such as gallic acid, oxalic acid, behenic acid, stearic acid, arachidic acid, palmitic acid and lauric acid. Other examples include the organic silver salts described in paragraph No. “0193” of JP 2001-83659 A. Regarding the preparation method of the organic silver salt and the particle size of the organic silver salt, the description in paragraphs “0194” to “0197” of the publication can be referred to.
As the organic silver salt according to the present invention, JP-A 2001-4890
2 Publication paragraph number “0028” to paragraph number “0033”,
Japanese Patent Laid-Open No. 2000-72777 Paragraph No. "0025"-
The techniques described in paragraph number “0041” and the like can be used.

The photosensitive silver halide that can be used in the photothermographic material of the present invention (hereinafter referred to as the photosensitive silver halide according to the present invention) is originally a unique property of silver halide crystals. Or, it can absorb visible light or infrared light by an artificial physicochemical method, and when it absorbs visible light or infrared light, physicochemical changes occur in the silver halide crystal or on the crystal surface. Means a silver halide crystal grain that has been processed and prepared so that

The light-sensitive silver halide according to the present invention is described in P.
Chimieet Physiq by Glafkides
ue Photographique (Paul Mo
ntel, 1967), G.N. F. Photographic Emulsion Ch by Duffin
emissary (published by The Focal Press,
1966), V. L. Zelikman et al
By Making and Coating Photo
graphic Emulsion (TheFocal
It can be prepared as a silver halide grain emulsion by the method described in Press, 1964). Among these, the so-called controlled double jet method, in which silver halide grains are prepared while controlling the forming conditions, is preferable. The halogen composition is not particularly limited and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide and silver iodide. The formation of silver halide grains according to the present invention is usually divided into two stages, that is, silver halide seed grain (nucleus) generation and grain growth, and a method of continuously performing them at one time may be used. ) Forming and grain growth may be performed separately. As another example, JP-A-2001-83659, paragraph No. “006” may be used.
The technique described in "3" can be used.

The photosensitive silver halide according to the present invention preferably has a small average grain size in order to suppress white turbidity after image formation and obtain good image quality. The average particle size is 0.2 μm or less, more preferably 0.01 to 0.17.
μm, particularly 0.02 to 0.14 μm is preferable. The term "grain size" as used herein means the length of the edges of silver halide grains when the silver halide grains are cubic or octahedral so-called normal crystals. Further, when the silver halide grains are tabular grains, it means the diameter when converted into a circular image having the same area as the projected area of the main surface.

The particle size is preferably monodisperse. More specifically, the techniques described in paragraph Nos. “0064” to “0066” of JP 2001-83659 A can be used. The shape of the grains may be any of cubic, octahedral, tetradecahedral and tabular silver halide grains. In the case of tabular silver halide grains, the average aspect ratio is generally 1.5 or more and 100 or less, preferably 2 or more and 50 or less.
The following is good. These are US Pat. No. 5,264,337.
No. 5,314,798, No. 5,320,95
The technique described in No. 8 etc. can be applied. As a particle forming technique, Japanese Patent Laid-Open No. 2001-83659, paragraph number “006” is used.
The techniques described in "8" to paragraph number "0090" can be applied.

The photosensitive silver halide according to the present invention preferably contains an ion of a transition metal belonging to Groups 6 to 11 of the Periodic Table of the Elements in order to improve illuminance failure. The preferred content is 1 × 10 ⁻⁹ to 1 × 10 ⁻² mol per mol of silver,
More preferably, it is in the range of 1 × 10 ⁻⁸ to 1 × 10 ⁻⁴ .
A preferred transition metal complex or complex ion has a general formula [M
L ₆ ] ^m (where M is a transition metal selected from the elements of groups 6 to 11 of the periodic table, L is a ligand, and m is 0, −,
2-, 3-, or 4-) is represented. Specific examples of the ligand represented by L include halogen ions (fluorine ion, chlorine ion, etc.), cyanide, cyanate, thiocyanate, selenocyanate, tellurocyanate, azide and aco ligands, nitrosyl, Thionitrosyl and the like can be mentioned, with preference given to ako, nitrosyl and thionitrosyl. When an aco ligand is present, it preferably occupies one or two of the ligands. As the transition metal coordination complex ion, those described in JP-A-2001-83659, paragraph number “0094” to paragraph number “0095” can be used.

The photosensitive silver halide according to the present invention is preferably chemically sensitized. Regarding the preferable chemical sensitization, JP-A 2000-112057, paragraph No. “0”
044 ”to the paragraph number“ 0045 ”,
Technology can be used.

The photosensitive silver halide according to the present invention is preferably spectrally sensitized. Regarding preferable spectral sensitization, paragraph number “00” of JP 2001-83659 A is referred to.
The sensitizing dyes and techniques described in "99" to paragraph "0144" can be used.

The photosensitive silver halide according to the present invention is a dye which does not have a spectral sensitizing effect by itself, or a substance which does not substantially absorb visible light, together with a sensitizing dye, and exhibits a supersensitizing effect. You may use the supersensitizer. As the supersensitizer, compounds described in JP-A No. 2001-83659, paragraph numbers “0148” to “0152” can be used.

In the present invention, in addition to the supersensitizer described above, Japanese Patent Application No. 12-070296, paragraph No. “00” may be used.
22 ”to the compound represented by the general formula (1) described in Paragraph No.“ 0028 ”and a macrocyclic compound having at least one hetero atom can be used as a supersensitizer. Specific examples of the compound represented by the general formula (1) are described in Japanese Patent Application No. 12-07 / 12.
No. 0296 Specification, paragraph number “0034” to paragraph number “0”
039 ". Further, the macrocyclic compound having a hetero atom is described in Japanese Patent Application No. 12-070296, paragraph number “0044” to paragraph number “0054”.

The reducing agent that can be used in the photothermographic material of the present invention can be appropriately selected from the reducing agents known in the technical field of photothermographic materials.
In particular, when an aliphatic carboxylic acid silver salt is used as the organic silver salt, polyphenols in which two or more hydroxyphenyl groups are linked by an alkylene group or sulfur, especially at a position adjacent to the hydroxy substitution position of the hydroxyphenyl group are used. Two or more hydroxyphenyl groups in which at least one is substituted with an alkyl group (eg, methyl group, ethyl group, propyl group, t-butyl group, cyclohexyl group, etc.) or acyl group (eg, acetyl group, propionyl group, etc.) Bisphenols linked by an alkylene group or sulfur are preferred.

For example, the hindered phenol type reducing agents described in paragraph Nos. “0047” to “0048” of JP 2000-112057 A are preferably used in the present invention. For specific examples of the compound, refer to JP-A 2000-112057, paragraph number “005”.
0 ”to paragraph number“ 0051 ”. The amount of the reducing agent used is 1 × 10 ^-2 to 10 mol, preferably 1 × 10 ^{-2 to} 1.5 mol, per mol of silver.

The binder that can be used in the photothermographic material of the present invention (hereinafter referred to as the binder of the present invention) is transparent or translucent, generally colorless, and is a natural polymer or a synthetic polymer. As an example of the binder according to the present invention, JP-A-2001-66725, paragraph number “0”
And natural or synthetic polymers described in "193".
As the binder according to the present invention, polyvinyl acetals are preferable, and polyvinyl butyral is particularly preferable. As the amount of the binder used, the ratio of the binder to the organic silver salt is preferably 15: 1 to 1: 2, and particularly preferably 8: 1 to 1: 1. A polymer latex can also be preferably used as the binder according to the present invention. Regarding the polymer latex, JP-A-2001-6
6725 gazette paragraph number "0194" -paragraph number "020
The compounds and techniques described in "3" can be applied.

By using a crosslinking agent, the binder according to the present invention is expected to have an effect of improving film adhesion, reducing uneven development, and suppressing fog during storage and generation of printout silver after development. it can. JP-A-50-9
The aldehyde-based, epoxy-based, ethyleneimine-based, vinylsulfone-based, sulfonic acid ester-based, acryloyl-based, carbodiimide-based, and silane compound-based crosslinking agents described in 6216 can be used, but as preferred crosslinking agents. Is an isocyanate compound, a silane compound, an epoxy compound, or an acid anhydride.

For the isocyanate compound, the compounds and techniques described in paragraph Nos. “0159” to “0168” of JP 2001-83659 A can be applied. Regarding epoxy compounds, JP 2001-8
3659 gazette paragraph number "0170" -paragraph number "018"
The compounds and techniques described in "0" can be applied. For the acid anhydride, the compounds and techniques described in paragraph numbers “0182” to “0187” of JP 2001-83659 A can be applied. Regarding the silane compound, Japanese Patent Application No. 12-77904, paragraph No. “002”
The compounds and techniques described in 2 ”to paragraph number“ 0028 ”can be applied.

In the photothermographic material of the invention, a toning agent can be used if necessary. As toning agents that can be used in the present invention, there are JP-A-2000-198757.
The compounds and technologies described in paragraph number “0064” to paragraph number “0066” of the publication can be applied.

In the photothermographic material of the present invention, a filter layer is formed on the same side as the photosensitive layer or on the opposite side in order to control the amount or wavelength distribution of light passing through the photosensitive layer, or the photosensitive layer is formed. It is preferable to contain a dye or a pigment. As the dye used in the present invention, known compounds that absorb light in various wavelength regions depending on the color sensitivity of the light-sensitive material can be used. For example, when the photothermographic material of the present invention is used as an image recording material for infrared light, Japanese Patent Application No. 11-25
No. 5557, paragraph number “0032” to paragraph number “0”
It is preferable to use a squarylium dye having a thiopyrylium nucleus, a squarylium dye having a pyrylium nucleus, and the like as disclosed in “034”. It is also possible to use a croconium dye having a thiopyrylium nucleus or a croconium dye having a pyrylium nucleus similar to the squarylium dye.

In the photothermographic material of the present invention, since a reducing agent having a proton such as bisphenols and sulfonamidephenols is used as the reducing agent,
It is preferable to contain a compound capable of deactivating the reducing agent by generating active species capable of abstracting hydrogen. As the colorless photo-oxidizable substance, a compound capable of generating a free radical as a reactive species during exposure is preferable. As these compounds, Japanese Patent Application No. 2000-
057004 specification paragraph number “0065” to paragraph number “0069” the biimidazolyl compound which is disclosed, and Japanese Patent Application No. 2000-057004 specification paragraph number “00”.
71 ”to paragraph number“ 0082 ”can be used.

In the photothermographic material of the present invention, a compound that releases a halogen atom as an active species can be used as a compound that inactivates the reducing agent and prevents the reducing agent from reducing the organic silver salt to silver. . Specific examples of the compound that produces an active halogen atom include Japanese Patent Application No. 2000-0570.
04 specification paragraph number "0086" -paragraph number "010
The compounds disclosed in "2" can be used.

A silver saving agent can be used in the photothermographic material of the present invention. The silver saving agent refers to a compound capable of reducing the amount of silver necessary to obtain a constant silver image density. There are various conceivable modes of action for the function of reducing the amount, but compounds having a function of improving the covering power of developed silver are preferable.
Here, the covering power of developed silver means the optical density per unit amount of silver. Examples of the silver-saving agent that can be used in the present invention include hydrazine derivative compounds disclosed in Japanese Patent Application No. 11-238293, paragraph number “0075” to paragraph number “0081”, and Japanese Patent Application No. 11-238293.
No. Paragraph number "0109" to Paragraph number "0132"
Disclosed in Japanese Patent Application No. 11-2382
No. 93 specification, paragraph number “0150” to paragraph number “015”
And quaternary onium compounds disclosed in "8".

The photothermographic material of the present invention comprises an organic silver salt, a photosensitive silver halide, a reducing agent, and a support on which a subbing layer is provided.
And a binder containing a photosensitive layer, but it is preferable to form a non-photosensitive layer on the photosensitive layer.
For example, a protective layer is preferably provided on the photosensitive layer for the purpose of protecting the photosensitive layer, and a backing layer is preferably provided on the opposite surface of the support for preventing sticking. As a binder used for these protective layers and backing layers, a polymer having a higher glass transition point than the photosensitive layer and hardly causing scratches or deformation, for example, a polymer such as cellulose acetate or cellulose acetate butyrate is selected from the above binders. Be done. In order to adjust gradation, two or more photosensitive layers may be provided on one side of the support, or one or more photosensitive layers may be provided on both sides of the support.

The heat-developable light-sensitive material of the present invention is formed by dissolving or dispersing the materials of the above-mentioned constituent layers in a solvent to prepare a coating solution, applying a plurality of the coating solutions at the same time, and then performing a heat treatment. Preferably. Here, "a plurality of layers are coated at the same time" means that a coating solution for each constituent layer (for example, a photosensitive layer and a protective layer) is prepared, and when the coating solution is applied to a support, each layer is separately coated and dried. It means that each constituent layer can be formed in a state where the steps of simultaneously performing multilayer coating and drying can be performed simultaneously. That is, it is preferable to provide the upper layer before the residual amount of all the solvents in the lower layer becomes, for example, 70% by mass or less.

There are no particular restrictions on the method for applying multiple layers of each constituent layer at the same time, and known methods such as bar coater method, curtain coating method, dipping method, air knife method, hopper coating method and extrusion coating method are used. be able to. Of these, a pre-weighing type coating method called an extrusion coating method is more preferable. Unlike the slide coating method, the extrusion coating method is suitable for precision coating and organic solvent coating because the solvent does not evaporate on the slide surface. This coating method has been described for the side having the photosensitive layer, but the same applies to the case where the backcoat layer is coated together with undercoating. Of course, the photothermographic material of the present invention may be an aqueous solvent.

The developing conditions for the photothermographic material of the present invention will be described. Development conditions will vary depending on the equipment, equipment, or means used, but typically involve heating the imagewise exposed photothermographic dry imaging material at a suitable elevated temperature. The latent image obtained after exposure is, for example,
About 80-200 ° C, preferably about 100-200 ° C,
Development can be performed by heating for approximately 1 second to 2 minutes. If the heating temperature is 80 ° C or lower, sufficient image density cannot be obtained in a short time, and if the heating temperature is 200 ° C or higher, the binder melts and transfers to the roller, which adversely affects not only the image itself but also the transportability and the developing machine. . By heating, a silver image is generated by a redox reaction between an organic silver salt (which functions as an oxidizing agent) and a reducing agent.

This reaction process proceeds without supplying a treatment liquid such as water from the outside. The equipment, device or means for heating is a hot plate, iron, hot roller,
It may be performed by a heating means typical of a heat generator using carbon or white titanium. In the case where the photothermographic material of the invention has a protective layer, it is preferable that the surface on the side having the protective layer is brought into contact with a heating means for heat treatment in order to perform uniform heating, heat efficiency and workability. From the viewpoint of the above, it is preferable that the surface is conveyed while being brought into contact with a heat roller, heated, and developed.

During development, the photothermographic material of the present invention contains a solvent in an amount of 5 to 1000 mg / m ² , preferably 100.
Prepare to be ˜500 mg / m ² . As a result, the photothermographic material has high sensitivity, low fog and high maximum density.

As the solvent, ketones such as acetone, methyl ethyl ketone and isophorone, methyl alcohol,
Alcohols such as ethyl alcohol, isopropyl alcohol, cyclohexanol and benzyl alcohol, glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol and hexylene glycol, ether alcohols such as ethylene glycol monomethyl ether and diethylene glycol monoethyl ether. , Ethers such as isopropyl ether, esters such as ethyl acetate and butyl acetate,
Examples thereof include chlorides such as methylene chloride and dichlorobenzene, hydrocarbons and the like. In addition, water, formamide, dimethylformamide, toluidine, tetrahydrofuran,
Examples thereof include acetic acid. However, it is not limited to these. Further, these solvents can be used alone or in combination of several kinds.

The content of the solvent in the photothermographic material can be adjusted by changing the conditions such as the temperature conditions in the drying process after the coating process. Further, the content of the solvent can be measured by gas chromatography under conditions suitable for detecting the contained solvent.

The exposure conditions of the photothermographic material of the invention will be described. For exposure of the photothermographic material of the present invention, it is desirable to use a light source suitable for the color sensitivity imparted to the photothermographic material. For example, when infrared light can be felt, it can be applied to any light source in the infrared light range, but the laser power is high and the photothermographic material of the present invention is transparent. Infrared semiconductor lasers (780 nm, 820 nm) are preferably used from the viewpoints that they can be obtained.

The exposure of the photothermographic material of the present invention is preferably carried out by laser scanning exposure, and various exposure methods can be adopted.

A first preferable method is a method using a laser scanning exposure machine in which the angle formed by the scanning laser beam and the exposed surface of the photothermographic material is not substantially perpendicular. Here, “not substantially vertical” means an angle that is the most vertical during laser scanning, and is preferably 55 degrees or more and 88 degrees or less, more preferably 60 degrees or more and 8 degrees or less.
It is 6 degrees or less, more preferably 65 degrees or more and 84 degrees or less, and most preferably 70 degrees or more and 82 degrees or less. The beam spot diameter on the exposed surface of the photosensitive material when the laser light is scanned on the photosensitive material is preferably 200 μm or less, more preferably 100 μm or less. It is preferable that the spot diameter is smaller because the angle of deviation of the laser incident angle from the vertical can be reduced. The lower limit of the beam spot diameter is 10 μm. By performing such laser scanning exposure, it is possible to reduce image quality deterioration due to reflected light such as interference fringe-like unevenness.

As the second method, it is also preferable to perform exposure by using a laser scanning exposure device that emits scanning laser light of longitudinal multi. Image deterioration due to interference fringe-like unevenness is reduced as compared with the vertical single mode scanning laser light. In order to make the vertical multi, it is preferable to use the returning light by the multiplexing or to apply high frequency superposition. Here, the vertical multi means that the exposure wavelength is not single, and normally the distribution of the exposure wavelength is 5 nm or more, preferably 10 nm or more.
The upper limit of the exposure wavelength distribution is not particularly limited, but usually 60
It is about nm.

As a third aspect, it is also preferable to form an image by scanning exposure using two or more lasers. An image recording method using a plurality of lasers is a technique used in an image writing means of a laser printer or a digital copying machine, which writes an image in a plurality of lines in one scanning because of the demand for higher resolution and higher speed. There is, for example, Japanese Patent Application Laid-Open No. 60-166916. This is a method in which laser light emitted from a light source unit is deflected and scanned by a polygon mirror to form an image on a photoconductor through an fθ lens or the like. This is the same laser scanning optics in principle as a laser imager. It is a device. The image formation of the laser beam on the photothermographic material in the image writing means of a laser printer or a digital copying machine is
For the purpose of writing an image on a plurality of lines by one scan, the next laser beam is imaged with a shift of one line from the image formation position of one laser beam. Specifically, the two light beams are several tens of μm on the image plane in the sub-scanning direction.
They are close to each other at an order interval and the print density is 400 dp.
i (here, 1 inch, that is, the printing density of 1 dot per 2.54 cm is defined as dpi (dot per inch)), the pitch of two beams in the sub-scanning direction is 63.5 μ.
m is 42.3 μm at 600 dpi.

Unlike the method of shifting the resolution in the sub-scanning direction, it is also preferable to form an image by converging two or more lasers at the same location on the exposure surface while changing the incident angle. At this time, when the exposure energy on the exposure surface when writing with one normal laser (wavelength λ [nm]) is E, N lasers used for exposure have the same wavelength (wavelength λ [n]
m]) and the same exposure energy (En), 0.
The range of 9 × E ≦ En × N ≦ 1.1 × E is preferable. By doing so, energy is secured on the exposed surface, but the reflection of each laser light to the photosensitive layer is reduced because the exposure energy of the laser is low,
As a result, the generation of interference fringes can be suppressed. In the above description, the wavelength of a plurality of lasers is the same as λ, but different wavelengths may be used. In this case, λ [nm]
For (λ-30) <λ1, λ2 ... λn ≦ (λ +
It is preferably within the range of 30).

In the exposure methods of the above-mentioned first, second and third aspects, the laser used for scanning exposure is a well-known solid laser such as ruby laser, YAG laser, glass laser; He- Ne laser, Ar ion laser, Kr ion laser, CO
₂ laser, CO laser, He-Cd laser, N ₂ laser, gas laser such as excimer laser; InG
aP laser, AlGaAs laser, GaAsP laser, InGaAs laser, InAsP laser, C
A semiconductor laser such as a dSnP ₂ laser or a GaSb laser; a chemical laser, a dye laser or the like can be appropriately selected and used depending on the application, but among them, the wavelength is 600 to 1200 n due to the problems of maintenance and the size of the light source.
m semiconductor laser is preferably used.

In a laser used in a laser imager or a laser imagesetter, the beam spot diameter on the exposed surface when scanning a photothermographic material generally has a short axis diameter of 5 to 75 μm and a long axis diameter. 5 as diameter
The laser beam scanning speed can be set to an optimum value for each photothermographic material by the sensitivity and laser power at the laser oscillation wavelength peculiar to the photothermographic material.

[0093]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.
In the examples, the photosensitive layer is represented as the image forming layer.

Example 1 [Preparation of undercoated (undercoating layer coated) support] Corona discharge treatment under conditions of 10 W / m ² · min on both sides of a biaxially stretched polyethylene terephthalate film having a blue dye concentration of 0.185. Was applied to one side of the following << coating liquid for undercoating underlayer on the backcoat surface side >> so as to have a dry film thickness of 0.06 μm, and then dried at 140 ° C. Coating liquid for pulling upper layer >> dry film thickness 0.2 μm
And then dried at 140 ° C. On the opposite surface, the following << coating liquid for undercoating lower layer on image forming surface >> was applied so as to have a dry film thickness of 0.2 μm, and then the following << coating liquid for undercoating upper layer on image forming surface >> Dry film thickness 0.08μ
The coating was applied so as to have a thickness of m and then dried at 140 ° C. These were heat-treated at 125 ° C. for 2 minutes to prepare an undersampled sample 1-1. << Backcoat surface side undercoating lower layer coating liquid >> Styrene / glycidyl methacrylate / butyl acrylate 16.0 g (20/20/40) copolymerized polymer latex (solid content 30%) Styrene / butyl acrylate / hydroxymethyl methacrylate (25 / 45/30) copolymerized polymer latex (solid content 30%) 4.0 g SnO ₂ sol (solid content 10%) 91 g (synthesized by the method described in JP-A-10-059720) Surfactant (A) 0. Distilled water was added to 5 g or more to make 1000 ml to obtain a coating liquid. << Backcoat surface side undercoating upper layer coating liquid >> Modified aqueous polyester A (solid content 18%) 215.0 g Surfactant (A) 0.4 g True spherical silica matting agent Seahoster KE-P50 (manufactured by Nippon Shokubai Co., Ltd.) ) Distilled water was added to 0.3 g or more to make 1000 ml to obtain a coating liquid. << Synthesis of Modified Aqueous Polyester A >> In a polycondensation reaction vessel, 35.4 parts by mass of dimethyl terephthalate, 33.63 parts by mass of dimethyl isophthalate, 17.92 parts by mass of dimethyl 5-sulfo-isophthalic acid sodium salt, ethylene glycol. 62 parts by mass, calcium acetate monohydrate 0.065
Mass parts, manganese acetate tetrahydrate 0.022 parts by mass, under a nitrogen stream, after performing an ester exchange reaction while distilling off methanol at 170 to 220 ° C., trimethyl phosphate 0.04 parts by mass, As a polycondensation catalyst, 0.04 parts by mass of antimony trioxide and 6.8 parts by mass of 1,4-cyclohexanedicarboxylic acid were added, and at a reaction temperature of 220 to 235 ° C., a theoretical amount of water was distilled off to effect esterification. went. Then, the pressure inside the reaction system was further reduced over about 1 hour and the temperature was raised, and finally polycondensation was performed at 280 ° C. and 133 Pa or less for about 1 hour to obtain a precursor of modified aqueous polyester A-1.
The intrinsic viscosity of the precursor was 0.33.

2 L equipped with a stirring blade, a reflux condenser and a thermometer
850 ml of pure water was put into the three-necked flask described above, and 150 g of the above precursor was gradually added while rotating the stirring blade. After stirring at room temperature for 30 minutes as it was, it was heated for 1.5 hours so that the internal temperature became 98 ° C., and heated and dissolved at this temperature for 3 hours. After completion of heating, the mixture was cooled to room temperature over 1 hour and left overnight to prepare a solution having a solid content concentration of 15% by mass.

The above precursor solution 19 was placed in a 3 L four-necked flask equipped with a stirring blade, a reflux condenser, a thermometer, and a dropping funnel.
Add 00 ml, and while rotating the stirring blade, set the internal temperature to 8
Heated to 0 ° C. In this, 2 of ammonium peroxide
6.52 ml of a 4% aqueous solution was added, and a monomer mixture liquid (glycidyl methacrylate 28.5 g, ethyl acrylate 21.
4 g and methyl methacrylate 21.4 g) were added dropwise over 30 minutes, and the reaction was continued for another 3 hours. Then, the solution was cooled to 30 ° C. or lower and filtered to prepare a solution of modified aqueous polyester A having a solid content concentration of 18% by mass. << Coating liquid for undercoat lower layer on image forming surface side >> Styrene / butyl acrylate / hydroxymethyl methacrylate 70 g (25/45/30) copolymerized polymer latex (solid content 30%) Unitox D-110 (Acre Peterlite Co., USA) ) 5.0 g Surfactant (A) 0.3 g Distilled water was added to the above to make 1000 ml to obtain a coating liquid. << Coating liquid for undercoat upper layer on image forming surface side >> Ethylene copolymer polyvinyl alcohol RS2117 (manufactured by Kuraray Co., Ltd.) (solid content 5%) 80.0 g Styrene / butyl acrylate / hydroxymethyl methacrylate (25/45/30) Copolymerized polymer latex (solid content 30%) 2.4 g Surfactant (A) 0.4 g True spherical silica matting agent Sea Hoster KE-P50 (manufactured by Nippon Shokubai Co., Ltd.) 0.3 g Distilled water is added to the above 1000 ml. To obtain a coating liquid having a solid content concentration of 0.5%.

[0097]

[Chemical 1]

The composition of the undercoating upper layer on the image forming surface side is shown in Table 1, and the amount of polymer latex L (mg / mg /
m ² ), the amount of matting agent M (mg / m ² ), and the film thickness D (μm), except that the backcoat surface side was drawn downward and the image forming surface side was lowered in the same manner as in Sample 1-1. Subtraction coating was performed to prepare subbing samples 1-2 to 1-17. The undercoated sample thus prepared was continuously coated with a solvent-based image forming layer and a water-based image forming layer and a back coat layer, respectively, to prepare a photothermographic material. [Application of image forming layer and back coat layer] (Preparation of silver halide emulsion A) 7.5 g of inert gelatin and 10 mg of potassium bromide were dissolved in 900 ml of water to adjust the temperature to 35 ° C and pH to 3.0. And then silver nitrate 74
370 ml of an aqueous solution containing g and potassium bromide and potassium iodide in a molar ratio of (98/2) with respect to silver nitrate in the same mole, [I
The r (NO) Cl ₅ ] salt was added by 1 × 10 ⁻⁶ mol per mol of silver and the rhodium chloride salt was added by 1 × 10 ⁻⁴ mol per mol of silver by the controlled double jet method while keeping the pAg at 7.7. . Then 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene was added and Na
Adjust the pH to 5 with OH and average particle size 0.06μ
m, coefficient of variation of projected diameter area with monodispersity of 10% 8%,
Cubic silver iodobromide grains having a [100] plane ratio of 87% were obtained.
This emulsion was subjected to coagulation sedimentation using a gelatin coagulant, desalting, and 0.1 g of phenoxyethanol was added thereto to adjust the pH to 5.
9, pAg 7.5 was adjusted, and chemical sensitization was performed with chloroauric acid and inorganic sulfur to obtain a silver halide emulsion A. (Preparation of Na Behenate Solution) 32.4 g of behenic acid, 9.9 g of arachidic acid, and 5.6 g of stearic acid were dissolved in 945 ml of pure water at 90 ° C. Next, 98 ml of a 1.5 mol / L sodium hydroxide aqueous solution was added while stirring at high speed. Next, after adding 0.93 ml of concentrated nitric acid, the temperature was 55 ° C.
After cooling to room temperature and stirring for 30 minutes, a sodium behenate solution was obtained. (Preparation of Preform Emulsion of Silver Behenate and Silver Halide Emulsion A) 15.1 g of the above silver halide emulsion A was added to the above-mentioned Na behenate solution and the pH was adjusted to 8. with a sodium hydroxide solution.
After adjusting to 1, 147 ml of 1 mol / L silver nitrate solution
Was added over 7 minutes, the mixture was stirred for further 20 minutes, and the water-soluble salts were removed by ultrafiltration. The obtained silver behenate had a mean particle size of 0.8 μm and a monodispersity of 8%. After formation of flocs in the dispersion, water was removed, and the mixture was washed 6 times with water and then dried to obtain preform emulsions of silver behenate and silver halide emulsion A.

A backcoat layer was applied on the backcoat side of the undercoated sample, and an image forming layer and an image forming layer protective layer were applied on the image forming side of the undercoat. The drying was carried out at 60 ° C. for 15 minutes. << Backcoat layer (solvent system) >> Cellulose acetate butyrate (10% methyl ethyl ketone solution) 15 ml / m ² Dye-A 7 mg / m ² Dye-B 7 mg / m ² Matting agent: Monodispersity 15%, average particle size 8 μm Monodisperse silica 90 mg / m ² C ₈ F ₁₇ (CH ₂ CH ₂ O) ₁₂ C ₈ F ₁₇ 50 mg / m ² C ₉ F ₁₇ -C ₆ H ₄ -SO ₃ Na 10 mg / m ²

[0100]

[Chemical 2]

<Image forming layer (solvent system)> To the preform emulsion obtained above, the following binders and materials were added, and further methyl ethyl ketone was added to prepare an image forming layer coating solution. It was applied so that the amount would be 1.9 g / m ² .

[0102]   Polyvinyl butyral Butvar B-79 (manufactured by Monsanto)                                                               98 g   Toluene 107g   Sensitizing dye (0.1% methanol solution) 1.7 ml   Pyridinium bromide perbromide (6% methanol solution) 3 ml   Calcium bromide (0.1% methanol solution) 1.7 ml   Oxidizing agent (10% methanol solution) 1.2 ml   2- (4-chlorobenzoyl) benzoic acid (12% methanol solution)                                                           9.2 ml   2-mercaptobenzimidazole (1% methanol solution) 11 ml   Tribromomethylsulfoquinoline (5% methanol solution) 17 ml   Developer; 1,1-bis (2-hydroxy-3,5-dimethylphenyl)     -2-Methylpropane (20% methanol solution) 29.5 ml

[0103]

[Chemical 3]

<< Protective Layer for Image Forming Layer (Solvent System) >> Acetone 5 ml / m ² Methyl ethyl ketone 21 ml / m ² Cellulose acetate butyrate 2.3 g / m ² Methanol 7 ml / m ² Phthalazine 250 mg / m ² Matting agent: Monodispersity 10%, average particle size 4 μm monodisperse silica 5 mg / m ² CH ₂ = CHSO ₂ CH ₂ CH ₂ OCH ₂ CH ₂ SO ₂ CH = CH ₂ 35 mg / m ² Fluorosurfactant C ₁₂ F ₂₅ (CH ₂ CH ₂ O) ₁₀ C ₁₂ F ₂₅ 10 mg / m ² C ₈ F ₁₇ —C ₆ H ₄ —SO ₃ Na 10 mg / m ₂ << Backcoat layer (water-based) >> 35 g of ethyl acetate,
The following compound B 2.5 g and compound D 7.5 g were added and dissolved by stirring. 50 g of a 10 mass% aqueous solution of polyvinyl alcohol previously dissolved was added to the solution, and 5
Stir with a homogenizer for minutes. Then, ethyl acetate was volatilized with a desolvent and finally diluted with water to obtain a color developer dispersion. Subsequently, the following compounds were added, and water was added to form a coating solution for the back coat layer. The coating solid content was 1.5 g / m 2.
^It was applied so that it became ² .

[0105]   Coloring dispersion 50g   Compound H 20g   Sildex H121 (Doikai Chemical Co., Ltd. spherical silica, average particle size 12 μm)                                                             1.8 g

[0106]

[Chemical 4]

<< Image Forming Layer (Aqueous System) >> The following materials were added to 1 mol of silver of the preform emulsion prepared above, and water was further added to prepare an image forming layer coating solution. It was applied so as to be 2.0 g / m ² .

[0108]   Luck Star 3307B (manufactured by Dainippon Ink and Chemicals, Inc.)                                                     397g in solid content   1,1-bis (2-hydroxy-3,5-dimethylphenyl)     -3,5,5-Trimethylhexane 149g   Polyhalogen compound-A 44g   Polyhalogen compound-B 14g   Sodium ethylthiosulfonate 0.30 g   Benzotriazole 1.0 g   Polyvinyl alcohol (PVA-235 manufactured by Kuraray Co., Ltd.) 11 g   6-isopropylphthalazine 13 g   Sodium dihydrogen orthophosphate dihydrate 0.37 g   Compound Z 9.7 g   Nucleating agent; Compound AA 5.0 g   Dye AA 783 nm coating amount that makes the optical density 0.3 (0.37 as a guide) g)   Compound C 2.0 g

[0109]

[Chemical 5]

[0110]

[Chemical 6]

<< Image-Forming Layer Protective Layer (Aqueous) >> Water was added to the following materials to make 1000 ml, and coating was performed so that the solid content of the polymer latex was 3.0 g / m ² .

Copolymer polymer latex of methyl methacrylate / styrene / 2-ethylhexyl acrylate / 2-hydroxyethyl methacrylate / acrylic acid = 58.9 / 8.6 / 25.4 / 5.1 / 2 (solid content 22%) 140 g Compound E 21 g C ₁₂ H ₂₅ (OCH ₂ CH ₂ ) ₁₀ OH 1.0 g C ₁₆ H ₃₃ (OCH ₂ CH ₂ ) ₁₀ OH 1.9 g Compound F 7.95 g Compound G 0.72 g Matting agent (polystyrene, particles Diameter 6.5 μm) 2.1 g Carnauba wax dispersed particles (particle diameter 0.10 μm) 1.6 g Polyvinyl alcohol (Kuraray Co., Ltd., PVA-235, 5% aqueous solution) 8.30 g

[0113]

[Chemical 7]

Under-prepared Sample 1 produced as described above
1 to 1-17, the heat-developable photosensitive material was evaluated as follows for the resistance to undercoat scratches on the image forming surface side, the adhesiveness of the image forming layer, and the blocking resistance to undercoat. The results obtained are shown in Table 1. <Evaluation method> (Image formation surface side undercoat scratch resistance) The undercoat-coated sample was cut into a size of 15 cm in length and 6 cm in width, and the sample was preliminarily conditioned at 23 ° C. and 55% RH for 24 hours. did. On the undercoating surface to which the photosensitive layer is applied, that is, on the image forming surface-side undercoating surface, place a 500 g weight attached to the bottom with black Racha paper cut into 1 cm squares, and pull it horizontally on the sample. The sample surface at the position where the friction coefficient was maximum and in the vicinity thereof was observed with an optical microscope, and the number of scratches having a length of 100 μm or more in the scratch direction was evaluated according to the following ranks. The black rusher paper was replaced for each test.

○: 20 or less Δ: 21 to 60 × × more than 60 (adhesiveness of image forming layer) A pencil hardness test according to JISK5400 was performed on a hot plate heated to 120 ° C. went. Evaluation criteria are 9H, 8H, 7H, 6H, 5 in order of hardness.
H, 4H, 3H, 2H, H, F, HB, B, 2B, 3
B, 4B, 5B and 6B. If the pencil hardness is 2H or more, the adhesion of the undercoat with the image forming layer immediately after the heat development treatment is sufficient, and was ranked as ◯. Other than that, there is a problem in practical use, so I marked it as x. (Blocking resistance of undercoating) 5 samples with undercoating applied
It was cut into squares of 30 cm, and 30 sheets were stacked. The top and bottom are sandwiched between glass plates with a thickness of 2 mm, which is one size larger than the sample, and 2 k
A load of g was applied and the mixture was left at 45 ° C. for 24 hours. After leaving
While releasing the load and visually checking the degree of sticking,
The samples were peeled off one by one and the rank evaluation was performed. 1
The ones without sticking were ranked as ○, and the others were ranked as × because there is a concern that they may stick to each other when they are preserved after undercoating.

[0116]

[Table 1]

As is clear from Table 1, L (polymer latex amount, mg / m ² ), M (matting agent amount, mg / m ² ).
When m ² ) and D (film thickness, μm) are set in a range satisfying the formulas 1 and 2 of claim 1 of the present invention, scratch resistance and good adhesion between the image forming layer and the undercoat are obtained. It can be seen that the blocking resistance of the subbing is good.

Example 2 Same as Example 1 except that the particle size of the polymer latex used for the upper layer of the undercoat on the image forming surface side, the particle size of the matting agent and the total film thickness of the undercoat on the image forming surface side are as shown in Table 2. Then, an undercoated sample was prepared and a photothermographic material was prepared. Table 2 shows the results of evaluations of the abrasion resistance on the image forming surface side, the adhesion of the image forming layer, and the blocking resistance of the undercoat.

[0119]

[Table 2]

As is clear from Table 2, when the embedding depth of the matting agent is in the range of 10% to 60% of the particle diameter of the matting agent, there is abrasion resistance and the adhesion between the image forming layer and the undercoat is good, It can be seen that the pulling blocking resistance is good. However, when the latex particle size is large, the amount of protrusion from the undercoating surface is large, adhesion is seen during high temperature storage in the blocking test, and when the matting agent burial depth is small and large, scratch resistance and blocking I had poor tolerance.

Example 3 Except that the particle size of the polymer latex, the particle size and the number of the matting agent used in the undercoating upper layer on the image forming surface side are as shown in Table 3,
In the same manner as in Example 1, an undercoated sample and a photothermographic material were produced. Table 3 shows the results of evaluations of the abrasion resistance on the image forming surface side, the adhesion of the image forming layer, and the blocking resistance of the undercoat.

[0122]

[Table 3]

As is clear from Table 3, when the number of matting agents per cm ² is 200,000 or more and 800,000 or less, scratch resistance is exhibited, adhesion between the image forming layer and the undercoat is good, and the undercoating is good. It can be seen that the blocking resistance of is good. In the abrasion test, the one having a large number of matting agents had many breakages of the undercoating surface starting from the matting agent. Further, when the number of matting agents was small or the particle size of latex was large, the amount of protrusion from the undercoating surface was large, adhesion was observed during high temperature storage in the blocking test, and blocking resistance was poor.

Example 4 (Preparation of Sample 4-1 after Undercoating) Image forming surface side Undercoating The matting agent used for the upper layer was changed to the one having a crosslinking group on the surface shown below, and the image forming surface side An undercoated sample 4-1 was prepared in the same manner as in Example 1 except that the composition of the coating liquid for the pulling upper layer was changed as follows. << Synthesis of a matting agent having a cross-linking group on the surface >> A mixture of 68.0 g of methyl methacrylate and 17.0 g of hydroxyethyl methacrylate to which 6.8 g of lauryl peroxide was added as a polymerization initiator was added separately to 440.0 g of water.
Was added to a solution prepared by dissolving 0.6 g of sodium dioctylsulfosuccinate and 6.0 g of polyvinylpyrrolidone with stirring, and stirred for 5 minutes. This mixture was then added to T. K. HOMO DISPER (TOKUSHU K
IKA CO. Manufactured by K.K.) at 2000 rpm for 30 minutes. This suspension was placed in a 1 L round bottom flask and
A polymerization reaction was carried out at 5 ° C for 5 hours. However, in this 5 hour polymerization reaction, 85 g of a 5 mass% gelatin aqueous solution was added to the flask after the lapse of 3 hours in the first half, and the stirring was stopped for 2 hours while keeping the temperature at 70 ° C. It was then cooled. The produced polymer fine particles were separated by filtration to obtain a matting agent P-1. The average particle size of the obtained matting agent was 0.7 μm. << Coating Liquid for Image Forming Surface Side Undercoat Upper Layer >> Styrene / Glycidyl Methacrylate / Butyl Acrylate 2.9 g (20/20/40) Copolymer Latex (Solid Content 30%) Styrene / Butyl Acrylate / Hydroxymethyl Methacrylate (25 / 45/30) Copolymer latex (solid content 30%) 11.5 g Surfactant (A) 0.4 g Matting agent; P-1 0.3 g Distilled water is added to 1000 ml to make solid content concentration. The coating liquid was 0.5%. (Preparation of undercoated sample 4-2) The matting agent used for the undercoating upper layer on the image forming surface side is changed to the matting agent having a cross-linking group on the surface, and the coating solution for the undercoating upper layer on the image forming surface side is shown below. An undercoated sample 4-2 was prepared in the same manner as in Example 1 except that the composition was changed as follows. << Synthesis of Matting Agent Having Crosslinking Group on Surface >> 68.0 g of methyl methacrylate, 17 glydidyl methacrylate.
A mixture of 0 g of a polymerization initiator, 6.8 g of lauryl peroxide, was separately added to 440.0 g of water while stirring with a solution of 0.6 g of sodium dioctylsulfosuccinate and 6.0 g of polyvinylpyrrolidone. Stir for 5 minutes. This mixture was then added to T. K.
HOMO DISPER (TOKUSHU KIKAC
O. Manufactured by K.K.) at 2000 rpm for 30 minutes.
This suspension was placed in a 1 L round bottom flask, and a polymerization reaction was carried out at 70 ° C. for 5 hours. However, in this 5 hour polymerization reaction, 85 g of a 5 mass% gelatin aqueous solution was added to the flask after the lapse of 3 hours in the first half, and the stirring was stopped for 2 hours while keeping the temperature at 70 ° C. It was then cooled. The produced polymer fine particles were separated by filtration to obtain a matting agent P-2. The average particle size of the obtained matting agent was 0.35 μm. << Coating Liquid for Image Forming Surface Side Undercoat Upper Layer >> Styrene / Glycidyl Methacrylate / Butyl Acrylate 2.9 g (20/20/40) Copolymer Latex (Solid Content 30%) Styrene / Butyl Acrylate / Hydroxymethyl Methacrylate (25 / 45/30) Copolymer latex (solid content 30%) 11.5 g Surfactant (A) 0.4 g Matting agent; P-2 0.3 g Distilled water is added to 1000 ml to make solid content concentration. The coating liquid was 0.5%. (Preparation of subsampled sample 4-3) Subsampled sample 4 was prepared in the same manner as in sample 4-1 except that the matting agent was changed to a spherical silica matting agent, Seahoster KE-P50 (manufactured by Nippon Shokubai Co., Ltd.). 3 was produced. (Preparation of undercoated sample 4-4) The particle size of the polymer latex used in the coating liquid for the undercoating upper layer on the image forming surface side is 0.6.
A subsampled sample 4-4 was prepared in the same manner as the sample 4-2 except that the sample having a thickness of μm was used.

The image-forming layer and the back coat layer similar to those in Example 1 were continuously applied to the subbing sample thus produced to prepare a photothermographic material. Table 4 shows the results of evaluation of the resistance to scratches on the image forming surface side, the adhesion of the image forming layer, and the blocking resistance to the undercoat.

[0126]

[Table 4]

As is clear from Table 4, in the case of the sample using the matting agent whose surface is modified with a cross-linking group, scratch resistance is sufficient even if a water-soluble polymer is not used in the undercoating upper layer on the image forming surface side. It is found that the adhesion between the image forming layer and the undercoat is good, and the blocking resistance of the undercoat is excellent. With the polymer latex alone, when a matting agent whose surface was not modified with a cross-linking group was used, in the scratch test, the undercoating surface was broken, probably because the binding force between the matting agent and the undercoating was weak. In addition, when the particle size of the polymer latex was large, the amount of protrusion from the undercoating surface was large, adhesion was observed during high temperature storage in the blocking test, and blocking resistance was poor.

Example 5 Undercoating in the same manner as in Example 1 except that the particle size of the polymer latex used for the upper layer of the image forming surface side, the particle size of the matting agent and the film thickness of the undercoating are as shown in Table 5. Prepared sample,
A photothermographic material was prepared. Table 5 shows the results of evaluation of the resistance to scratches on the image forming surface side, the adhesion of the image forming layer, and the blocking resistance to the undercoat.

[0129]

[Table 5]

As is clear from Table 5, when the ratio of the undercoating film thickness to the particle size of the matting agent is in the range described in claim 5 of the present invention, the scratch resistance is sufficient and the image forming layer and It can be seen that the adhesion of the pulling is good and the blocking resistance of the undercoating is excellent. The polymer latex having a large particle size had a large amount of protrusion from the undercoating surface, showed adhesion during storage at high temperature in the blocking test, and had poor blocking resistance. Further, when the subbing film thickness was larger than 4/5 of the particle size of the matting agent, the height of the matting agent from the undercoating surface was not sufficient, and the blocking resistance was poor even if the latex particle size was small. When the subbing film thickness was smaller than ⅕ of the particle size of the matting agent, the matte was severely removed and scratches were observed.

[0131]

INDUSTRIAL APPLICABILITY According to the present invention, a photothermographic material having a subbing layer which is less likely to cause blocking during storage, is less likely to be scratched during transport, and has excellent adhesion to the image forming layer during development and immediately after development. It has a remarkably excellent effect of being able to provide.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H123 AB00 AB03 AB23 AB28 BA13                       BA16 BA45 BB00 BB15 BC00                       BC14 CB00 CB03

Claims (7)

[Claims] 1. A photothermographic material comprising a photosensitive silver halide, a non-photosensitive organic silver salt, and a photosensitive layer containing a reducing agent for the organic silver salt on at least one surface of a support,
At least one undercoat layer containing a matting agent and a polymer latex having a primary particle size smaller than the particle size of the matting agent is provided between the support and the photosensitive layer. Amount of polymer latex in the separated layer L (mg / m
² ), the film thickness D (μm) of the layer, and the total matting agent amount M (mg / m ² ) in the undercoat layer simultaneously satisfy the following (formula 1) and (formula 2). Photothermographic material. (Equation 1) −9.19 × L−34.5 × M + 3920 × D> 180 (Equation 2) −27.9 × L + 36.7 × M + 6026 × D <200 2. A photothermographic material comprising, on at least one surface of a support, a photosensitive silver halide, a non-photosensitive organic silver salt, and a photosensitive layer containing a reducing agent for the organic silver salt,
An undercoat layer containing a matting agent, a polymer latex having a primary particle size smaller than the particle size of the matting agent, and a water-soluble polymer is provided between the support and the photosensitive layer. The burial depth of the matting agent is 10 to 60 of the particle diameter of the matting agent.
% Is a photothermographic material. 3. A photothermographic material having a photosensitive silver halide, a non-photosensitive organic silver salt, and a photosensitive layer containing a reducing agent for the organic silver salt on at least one surface of a support,
An undercoat layer containing a matting agent, a polymer latex having a primary particle size smaller than the particle size of the matting agent, and a water-soluble polymer is provided between the support and the photosensitive layer. The number of matting agents per cm ² is 20
A photothermographic material, characterized in that the number is from 10,000 to 800,000. 4. A photothermographic material comprising a photosensitive silver halide, a non-photosensitive organic silver salt, and a photosensitive layer containing a reducing agent for the organic silver salt on at least one surface of a support,
An undercoat layer containing a matting agent and a polymer latex having a primary particle size smaller than the particle size of the matting agent is provided between the support and the photosensitive layer, and the matting agent is a polymer latex or a water-soluble polymer. A photothermographic material having a reactive cross-linking group on its surface. 5. A photothermographic material comprising a photosensitive silver halide, a non-photosensitive organic silver salt, and a photosensitive layer containing a reducing agent for the organic silver salt on at least one surface of a support,
A plurality of undercoat layers are provided between the support and the photosensitive layer, a matting agent is contained in a layer different from the layer farthest from the support among the undercoat layers, and the support of the undercoat layer. Contains a polymer latex having a primary particle size smaller than the particle size of the matting agent and a water-soluble polymer in the layer farthest away from, and the total film thickness of all the subbing layers is the average particle size of the matting agent. A photothermographic material which is larger than 1/5 and smaller than 4/5. 6. The photothermographic material according to claim 1, wherein the water-soluble polymer is a water-soluble polymer containing polyvinyl alcohol as a main component. 7. The photothermographic material according to claim 1, wherein the water-soluble polymer is a water-soluble polymer containing a water-soluble polyester as a main component.