JPH09258366A - Heat-developable photosensitive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the photosensitive material low in fog and freed of heat deformation on the surface at the time of heat development and superior in heat resistance and photographic performance by incorporating a polymer containing chlorinated polypropylene and phthalazine in one of the layers of this photosensitive material. SOLUTION: This photosensitive material has at least one photosensitive layer containing silver halide emulsion grains and a reducible nonphotosensitive silver source and a silver reducing agent on one side of a support and a layer containing the polymer comprising the chlorinated polypropylene, and the phthalazine. It is preferred that this polymer is contained in a non-photosensitive layer located farther than the photosensitive layers and it is further preferred that it is used for the binder of a surface protective layer. The polymer containing layer has a thickness of 0.1-10μm, preferably, 0.2-5μm, and an amount of the phthalazine to be added is 2-5000mg/m<2> , preferably, 10-3000mg/m<2> .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photothermographic material (hereinafter referred to as "photosensitive material"), and more specifically to a photosensitive material which has a small fog and is less likely to undergo thermal deformation on the surface during thermal development.

[0002]

2. Description of the Related Art There are many known photosensitive materials which have a photosensitive layer on a support and which form an image by imagewise exposure. Among them, a technology for forming an image by thermal development is one of the systems that can protect the environment and simplify the image forming means.

A method of forming an image by heat development is described in, for example, US Pat. Nos. 3,152,904 and 3,45.
No. 7,075, and D. Morgan and B. Shelley (S
hely) "Silver System Heat Treated (Therm
ally Processed Silver Systems) "(Imaging Processes & Materials)
esand Materials) Neblette 8th Edition, Sturg
e), V. Walworth, A. Shepp
Edited, p. 2, 1969). Such a light-sensitive material comprises a reducible non-photosensitive silver source (eg organic silver salt), a catalytically active amount of a photocatalyst (eg silver halide), and a silver reducing agent dispersed in a normal (organic) binder matrix. It is contained in the state of Photosensitive material is stable at room temperature, but high temperature after exposure (for example, 80 ℃ or higher)
When heated to a high temperature, silver is produced through a redox reaction between a reducible silver source (which functions as an oxidizing agent) and a reducing agent. This oxidation-reduction reaction is promoted by the catalytic action of the latent image generated by the exposure. The silver formed by the reaction of the reducible silver salt in the exposed areas provides a black image, which contrasts with the unexposed areas, resulting in the formation of an image.

In such a light-sensitive material, a technique for suppressing fogging to a small extent is important. It is known to add an antifoggant or to provide a protective layer for the purpose of suppressing fog.

Examples of antifoggants include mercury compounds. The use of mercury compounds as antifoggants in light-sensitive materials is described, for example, in US Pat.
89,903. However, mercury compounds are environmentally unfavorable. Non-mercury antifoggants include, for example, U.S. Pat. Nos. 4,546,075 and 4,4.
52,885 and JP-A-59-57234.

As the protective layer, for example, Japanese Examined Patent Publication No.
5410 describes cellulose propionate as disclosed in JP-A-55-142331, JP-A-57-119341,
No. 57-101835 and No. 56-5535 describe a protective layer containing cellulose diacetate as a binder. Further, JP-A-58-28736 discloses an example in which a water impermeable layer is used as a protective layer. However, even if these techniques are used, the fog reducing effect is insufficient, and a more effective fog reducing technique has been desired.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a light-sensitive material having less fog, and particularly to provide a light-sensitive material having low fog even when stored in a high temperature and high humidity atmosphere for a long time. is there. Furthermore, it is to provide a light-sensitive material having excellent photographic performance such that the surface does not undergo thermal deformation during heat development, has excellent heat resistance, has a high maximum density, has low fog, and has high sensitivity.

[0008]

[Means for Solving the Problems]

(1) A photothermographic material comprising, on at least one surface of a support, at least one photosensitive layer containing silver halide emulsion grains, a reducible non-photosensitive silver source and a silver reducing agent, A photothermographic material, wherein the photosensitive material has a layer containing a polymer containing chlorinated polypropylene and contains phthalazine.

(2) The photothermographic material according to (1), wherein the layer containing the polymer containing chlorinated polypropylene is a non-photosensitive layer provided at a position farther from the support than the photosensitive layer.

(3) The photothermographic material according to (1) or (2), wherein the layer containing a polymer containing chlorinated polypropylene is a surface protective layer.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The "polymer containing chlorinated polypropylene" of the present invention (hereinafter referred to as "polymer of the present invention") means a polymer containing a repeating unit of chlorinated polypropylene described below in the molecular chain of the polymer. Is. The term "repeating unit of chlorinated polypropylene" as used herein refers to a polypropylene repeating unit in which some or all of the hydrogen atoms are replaced with chlorine and is represented by the following general formula.

[0012]

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The chlorine content of the chlorinated polypropylene of the polymer of the present invention (polypropylene repeating unit (CH ₂ · CH (C
H ₃ )) is represented by how many hydrogen atoms out of the 6 hydrogen atoms are replaced by chlorine), but there is no particular limitation. However, flow deformation of the surface protective layer may occur, which is not preferable. On the contrary, if the chlorine content is high, the surface protection layer may be fragile and may cause problems such as cracking of the surface protective layer. Usually, the preferable range of chlorine content is about 20 to 70%. However, the “chlorine content” mentioned here is an average value of the entire chlorinated polypropylene component, and may be a polymer in which monomers having various chlorine contents are copolymerized. Of course, acceptable monomers include propylene, which has a chlorine content of 0.

The polymer of the present invention may be copolymerized with other monomer units in addition to chlorinated polypropylene.
Other monomers include the above propylene,
Other monomers may also be copolymerized. For example, a polymer obtained by copolymerizing (CH ₂ —CH (SO ₂ Cl)) with chlorinated polypropylene is convenient because it can be crosslinked if necessary.

There is no particular restriction on the molecular weight of the chlorinated polypropylene of the present invention. However, those having a molecular weight of 1,000 or less are not preferable because the strength of the film is low and cracks may occur in the surface protective layer. On the contrary, if the molecular weight is too large, the viscosity of the coating solution becomes too large, which is not preferable for coating. From the above, the preferable range of the molecular weight cannot be generally stated depending on the coating method, but it is about 3,000 to 50.
0000, and more preferably 5000-200000.

The polymers of the present invention may be linear or branched polymers. Specific examples of the polymer of the present invention are shown below.

[0017]

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The polymers of the present invention are not limited to these. The polymer of the present invention is commercially available,
Super Clone HP215, the same HP620 (made by Nippon Paper Industries Co., Ltd.), etc. are mentioned.

The polymer of the present invention is preferably contained in a non-photosensitive layer provided at a position farther from the support than the photosensitive layer, and more preferably used as a binder for the surface protective layer. As the binder of those layers, the polymer of the present invention may be used alone, or in some cases, other polymers may be blended and used. These polymers include chlorinated polyethylene polyvinyl butyral, cellulose diacetate, cellulose acetate butyrate, cellulose triacetate and vinyl chloride. Of course, two or more kinds of chlorinated polypropylene may be blended.

The thickness of the layer containing the polymer of the present invention (the surface protective layer in a preferred embodiment) is 0.1 to 10 μm, preferably 0.2 to 5 μm. In addition to the binder, additives such as a matting agent, a slip agent, a cross-linking agent, a surfactant, a dye and a UV absorber may be added to the protective layer of the present invention. For more information on these additives, read the Product Licensing Index magazine.
Volume 92 (December 1971) No. 9232, 10th
It is described on page 7. Further, the above-mentioned reducing agent, a toning agent to be described later, an antifoggant, a hydrazine nucleating agent and the like may be added to the protective layer of the present invention, if necessary.

The method for applying the layer containing the polymer of the present invention (protective layer in a preferred embodiment) is not particularly limited. Known coating methods such as dipping method, bar coater method, air knife method, curtain coating method and hopper coating method can be used.

The protective layer may be coated and dried simultaneously with the photosensitive layer, or the photosensitive layer may be coated and dried, then coated and then dried.

The solvent of the coating liquid for the layer containing the polymer of the present invention (protective layer in a preferred embodiment) can be used without particular limitation as long as it is a solvent capable of dissolving the chlorinated olefin as the binder and the additive. Examples of preferred solvents include ethyl acetate, butyl acetate, methyl ethyl ketone,
Methyl isobutyl ketone, methylene chloride, toluene, xylene and the like can be mentioned. The concentration of the polymer (binder) of the present invention in the coating solution is not particularly limited,
Usually 0.5 wt% to 25 wt%, more preferably 1 wt% to 2
The range of 0 wt% is preferred.

The photosensitive material of the present invention contains phthalazine. Phthalazine may be added to the photosensitive layer or may be added to a layer other than the photosensitive layer, for example, a surface protective layer, an intermediate layer, an antihalation layer or an undercoat layer. It is preferably a non-photosensitive layer, more preferably a surface protective layer containing the polymer of the present invention. The amount of phthalazine added is 2 mg / m ² ~
5000 mg / m ² , preferably 10 mg / m ^{2 to} 3000 mg /
A range of m ² is desirable.

In the present invention, the silver halide is any photosensitive silver halide (eg, silver bromide, silver iodide, silver chloride, silver chlorobromide, silver iodobromide, silver chloroiodobromide, etc.). Although it may be present, it is preferable to contain iodine ion. The silver halide may be added to the photosensitive layer in any manner, with the silver halide being placed in close proximity to the reducible silver source. Generally, it is preferred that the silver halide contain an amount of 0.75 to 30% by weight, based on the reducible silver source. Silver halide may be prepared by conversion of the silver soap portion by reaction with a halide ion, may be preformed and added during the generation of the soap, or a combination of these methods is possible. The latter is preferred.

The reducible silver source of the present invention can be any material containing a source of reducible silver ions. Silver salts of organic and heteroorganic acids, especially long chains (10-30, preferably 1
Silver salts of aliphatic carboxylic acids having 5 to 25 carbon atoms) are preferred. Organic or inorganic silver salt complexes in which the ligand has a total stability constant for silver ions of 4.0 to 10.0 are also useful. Examples of suitable silver salts include Research Disclosure 17,
029 and 29,963, which include: Salts of organic acids (eg, gallic acid, oxalic acid, behenic acid, stearic acid, palmitic acid, lauric acid, etc.),
A carboxyalkyl thiourea salt of silver (for example, 1- (3
-Carboxypropyl) thiourea, 1- (3-carboxypropyl) -3,3-dimethylthiourea, etc.), a silver complex of a polymer reaction product of an aldehyde and a hydroxy-substituted aromatic carboxylic acid (for example, aldehydes (formaldehyde, Acetaldehyde, butyraldehyde), hydroxy-substituted acids (eg salicylic acid, benzoic acid, 3,
5-dihydroxybenzoic acid, 5,5-thiodisalicylic acid), silver salts or complexes of thioenes (for example, 3- (2
-Carboxyethyl) -4-hydroxymethyl-4-thiazoline-2-thioene, and 3-carboxymethyl-
4-thiazoline-2-thioene), imidazole, pyrazole, urazole, 1,2,4-thiazole, and 1
H-tetrazole, 3-amino-5-benzylthio-
Complex or salt of nitric acid and silver selected from 1,2,4-triazole and benzotriazole, saccharin,
Examples thereof include silver salts such as 5-chlorosalicylaldoxime and silver salts of mercaptides. The preferred silver source is silver stearate or silver behenate, particularly preferably silver behenate. The reducible silver source is preferably 3 g / m ^{2 in} terms of silver amount.
It is as follows. More preferably, it is 2 g / m ² or less.

Examples of the reducing agent for silver ions of the present invention include so-called photographic developers such as phenidone and hydroquinones.
Catechol and the like may be contained, but hindered phenol is preferred. Color light-sensitive materials such as those disclosed in U.S. Pat. No. 4,460,681 are also considered in the realization of the present invention.

Examples of suitable reducing agents are described in US Pat. No. 3,773.
0,448, 3,773,512, 3,5
93,863, and Research Disclosure 17,02.
9 and 29,963, and includes the following. Aminohydroxycycloalkenone compounds (for example, 2-hydroxy-piperidino-2-cyclohexenone), aminoreductones as precursors of developers.
tones) ester (eg piperidinohexose reductone monoacetate), N-hydroxyurea derivative (eg N-p-methylphenyl-N-hydroxyurea), aldehyde or ketone hydrazone (eg anthracene aldehyde phenylhydrazone) ), Phosphoramidophenols, phosphoramidoanilines, polyhydroxybenzenes (eg, hydroquinone, t-butyl-hydroquinone, isopropylhydroquinone, and (2,5-dihydroxy-phenyl) methylsulfone), sulfhydroxamic acids. (Eg, benzenesulfhydroxamic acid), sulfonamideanilines (eg, 4- (N-methanesulfonamido) aniline), 2-tetrazolylthiohydroquinones (eg,
2-methyl-5- (1-phenyl-5-tetrazolylthio) hydroquinone), tetrahydroquinoxalines (eg, 1,2,3,4-tetrahydroquinoxaline),
Amidooxins, azines (eg, aliphatic carboxylic acid aryl hydrazides and ascorbic acid combinations), polyhydroxybenzene and hydroxylamine combinations, reductones and / or hydrazines, hydroxanoic acids, azines and sulfonamide phenols Combination, α-cyanophenylacetic acid derivative, bis-
Combination of β-naphthol and 1,3-dihydroxybenzene derivative, 5-pyrazolones, sulfonamide phenol reducing agent, 2-phenylindane-
1,3-dione, etc., chroman, 1,4-dihydropyridines (eg, 2,6-dimexy-3,5-dicarboethoxy-1,4-dihydropyridine), bisphenols (eg, bis (2-hydroxy- 3-t-butyl-
5-methylphenyl) methane, bis (6-hydroxy-)
m-tri) mesitol, 2,2-bis (4-
Hydroxy-3-methylphenyl) propane, 4,4-
Examples thereof include ethylidene-bis (2-t-butyl 6-methyl) phenol, UV-sensitive ascorbic acid derivative and 3-pyrazolidones. A preferred reducing agent is a hindered phenol of the following general formula.

[0029]

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Here, R is generally hydrogen or an alkyl group having 10 or less carbon atoms (for example, —C ₄ H ₉ , 2,4,4).
-Trimethylpentyl), wherein R ⁵ and R ⁶ are alkyl groups having 5 or less carbon atoms (eg, methyl, ethyl, t
-Butyl and the like).

It is suitable to add these reducing agents in the range of 1 to 5000 mg / m ² , more preferably 10 to 1000 mg / m ² .

Suitable binders used in the photosensitive layer of the light-sensitive material of the present invention are transparent or translucent and generally colorless,
Natural polymers Synthetic resins, polymers and copolymers, other film forming media such as gelatin, gum arabic, polyvinyl alcohol, hydroxyethyl cellulose, cellulose acetate, cellulose acetate butyrate, polyvinylpyrrolidone, casein, starch, polyacrylic acid, poly Methyl methacrylic acid, polyvinyl chloride, polymethacrylic acid, (styrene-maleic anhydride) copolymer, (styrene-acrylonitrile)
Copolymers, (styrene-butadiene) copolymers, polyvinyl acetals (for example, polyvinyl formal and polyvinyl butyral), polyesters, polyurethanes, phenoxy resins, polyvinylidene chloride, polyepoxides, polycarbonates, polyvinyl acetates, cellulose esters, polyamides. There are kinds.
The binder may be formed by coating from water or an organic solvent or emulsion.

An antifoggant may be added to the light-sensitive material of the present invention in order to further reduce fog. Preferred antifoggants include compounds such as those disclosed in U.S. Pat. Nos. 3,874,946 and 4,756,999, -CX ¹ X ² X ³ (where X ¹ and X ² are A heterocyclic compound having one or more substituents represented by halogen (eg, F, Cl, Br and I) and X ³ is hydrogen or halogen. Examples of suitable antifoggants include:

[0034]

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[0035]

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Further, more preferred antifoggants are US Pat. No. 5,028,523 and British Patent Application No. 9222.
1383.4, No. 9300147.7 and No. 9
No. 311790.1.

If necessary, a hydrazine nucleating agent may be added to the light-sensitive material of the present invention for increasing the contrast. Among the hydrazine nucleating agents, compounds that increase the contrast are disclosed in JP-A 2-1
No. 2236, page 2, upper right column, line 19 to page 7, right upper column, line 3; and JP-A 3-174143, page 20, lower right column, line 1 to page 27, upper right column, line 20 General formula (I
The compounds described in I) and Compound Examples II-1 to II-54 can be preferably used.

Further, among the hydrazine nucleating agents, as a compound that promotes a high contrast, a compound represented by the general formula from page 13, upper right column, line 13 to page 16, upper left column, line 10 of JP-A-2-103536 can be used. II-m) to (II-p) and Compound Example II-1
To II-22 and the compounds described in JP-A-1-179939 can be preferably used.

A sensitizing dye may be added to the light-sensitive material of the present invention. For example, JP-A-60-140335 and 63-63.
-15245, 63-159841, 63-2
No. 31437, No. 63-259651, No. 63-30
4242, U.S. Pat. Nos. 4,639,414 and 4,439.
740,455, 4,741,966, 4,7
The sensitizing dyes described in Nos. 51,175 and 4,835,096 can be used.

As the support of the light-sensitive material of the present invention, polyester cellulose nitrate such as polyethylene terephthalate and polyethylene naphthalate, cellulose derivative such as cellulose acetate, paper, polystyrene and glass can be used.

If necessary, an undercoat layer may be provided on both sides or one side of these supports. As the undercoat layer, known layers such as vinylidene chloride, acrylic acid ester, vinyl acetate, cellulose derivative, polyester and polyurethane can be used.

The light-sensitive material of the present invention may be provided with a back layer, a filter layer, an antihalation layer, etc., in addition to the photosensitive layer and the protective layer existing thereon. These layers may be provided either on the surface of the support on which the photosensitive layer is provided or on the opposite surface. Further, the number of photosensitive layers may be two or more.

The method of exposing the light-sensitive material of the present invention is not particularly limited. For example, a tungsten lamp, a mercury lamp, a laser light source, an iodine lamp, a xenon lamp, a CRT light source, and the like can be used. A particularly preferred light source is a red or infrared laser. The wavelength of the infrared laser is preferably 750 nm or more, more preferably 800 nm or more. When exposing with laser light, apply laser light at 5 ° or more and 30 ° to the photosensitive material surface
The exposure is preferably performed at an angle of 8 ° or more and 20 ° or less.

The developing method of the light-sensitive material of the present invention is not particularly limited. The heating method is not limited, but in consideration of simplicity, a method of contacting with a heating plate or a drum, a method of holding in a heated space, a method of using high frequency heating, etc. are preferable. The heating temperature is 80 to 150 ° C, preferably 100 to 1
A range of 30 ° C is suitable. The heating time varies depending on the temperature and cannot be generally stated, but the range of 1 second to 120 seconds, preferably 5 seconds to 40 seconds is suitable.

[0045]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Example 1 (Preparation of coating solution for emulsion layer) (a) Preparation of silver halide grains A 22 g of phthalated gelatin and 30 mg of potassium bromide were dissolved in 700 ml of water, and the pH was adjusted to 5.0 at 35 ° C. After that, 159 ml of an aqueous solution containing 18.6 g of silver nitrate and an aqueous solution of potassium bromide and potassium iodide (92/8) at a molar ratio of pAg of 7.7 were added by the control double jet method over 10 minutes. Then, silver nitrate 55.
An aqueous solution containing 4 g of 476 ml and an aqueous solution containing potassium bromide were added over 30 minutes while keeping the pAg at 7.7.
After H was lowered to cause coagulation sedimentation and desalting, 0.1 g of phenoxyethanol was added to adjust the pH to 5.9 and pAg to 8.2, and the silver iodide content was 8 mol% inside the grain, 2 mol% on average.
The above silver iodobromide grains were prepared. The average particle size of the obtained particles is 0.081 μm, and the variation coefficient of the projected diameter area is 8
%, The {100} plane ratio was 88%.

(B) Preparation of Organic Fatty Acid Silver Emulsion B 10.6 g of behenic acid was put in 300 ml of water, dissolved by heating at 90 ° C., and sufficiently stirred to prepare 1N sodium hydroxide 3
1.1 ml was added and left as it was for 1 hour.
Thereafter, the mixture was cooled to 30 ° C., 7.0 ml of 1N phosphoric acid was added, and the mixture was sufficiently stirred and N-bromosuccinimide 0.0
1 g was added. Thereafter, silver halide grains A prepared in advance were added with stirring while heating at 40 ° C. so that the silver amount was 10 mol% with respect to behenic acid. Further, 25 ml of a 1N silver nitrate aqueous solution was continuously added over 2 minutes, and the mixture was left for 1 hour with stirring.

While stirring this aqueous mixture, 37 g of 1.2 wt% polyvinyl acetate in n-butyl acetate was gradually added to form flocs of the dispersion. After that, the water was removed, and the water was washed twice more. Next, polyvinyl butyral (molecular weight 3000) 2-butanone solution 2.5 wt%
20 cc was added and stirred at a sufficient speed for 10 minutes. Next, 40 g of 2-butanone and 6.0 g of polyvinyl butyral (molecular weight 4000) were added to the following compounds and stirred at a sufficient speed for 1 hour to complete the preparation of the organic fatty acid silver emulsion B. To the organic fatty acid silver prepared as described above, the following chemicals were added per mol of silver to prepare an emulsion coating solution.

[0048]

[Chemical 6]

(Preparation of Surface Protective Layer Coating Solution) The surface protective layer coating solution was prepared as follows. Binder (types are as shown in Table-1) 7.5g Solvent (type and amount are as shown in Table-1)

[0050]

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Further, phthalazine or phthalazinone was added to the emulsion layer or the surface protective layer so that the coating amount was as shown in Table-1.

(Preparation of Backing Layer Coating Solution) A backing layer coating solution was prepared as follows. Polyvinyl alcohol 256g Deionized water 46g Methanol 46g Antihalation dye A 0.05g Polymethylmethacrylate (particle size 10μm) 15.0g

[0053]

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The backing layer coating solution prepared as described above was applied to a 175 μm thick biaxially stretched polyethylene terephthalate film colored blue with Dye-B so that the absorbance at 810 nm was 1.2. Drying was performed at 75 ° C. for 5 minutes.

[0055]

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(Preparation of coating sample) The prepared coating solution was coated on the opposite surface coated with the backing layer of polyethylene terephthalate so that the coated silver amount was 1.5 g / m ^2, and dried. After that, the binder for the surface protective layer coating liquid is 2.3 g /
It was applied so as to be m ² and dried. Dry at 75 ℃
Performed for 5 minutes. A coated sample was prepared in this manner and evaluated as follows. The results are shown in Table 1.

(Evaluation of Photographic Performance) After the photographic material was exposed with a laser sensitometer equipped with a 810 nm diode, the photographic material was heated (developed) at 120 ° C. for 25 seconds, and the obtained image was evaluated (sensitivity and fog and The maximum density (Dmax) was measured by a densitometer (fresh photographic property). The sensitivity was evaluated by the reciprocal of the ratio of the exposure dose that gives a density 0.3 higher than the minimum density (Dmin), and was expressed by relative evaluation using the coated sample 105 as a reference. The angle between the exposed surface of the photographic material and the exposure laser beam is 80 de
It was g.

Further, the sample was stored in an atmosphere of 50 ° C. and 75% RH for 3 days, and then the same evaluation was carried out (thermophotographic property).

(Evaluation of heat resistance) 12 with fine irregularities
The surface of the sample is pressed against a stainless plate at 0 ° C. at a pressure of 200 g / 20 cm ² for 10 seconds, peeled off, and cooled at room temperature. If the unevenness of the stainless steel plate is visible on the surface of the sensitive material, it is x, and if it is not visible, it is ◯. The results are shown in Table 1.

[0060]

[Table 1]

Cellulose acetate butyrate A: CAB-171-
15S (manufactured by Eastman Chemical Co.) Chlorinated polyethylene B: Supercron HE510 (manufactured by Nippon Paper Industries Co., Ltd.) Chlorinated polypropylene C: Supercron HP620
(Manufactured by Nippon Paper Industries Co., Ltd.) Chlorinated polypropylene D: Supercron HP215
(Nippon Paper Industries Co., Ltd.)

The sample having the surface protective layer of the present invention has little fog after thermostatting and has good heat resistance, and the effect of the present invention is clear. Further, the sample of the present invention had no significant difference in transparency and the like as compared with the comparative example, and there was no problem in practical use.

Example 2 The silver halide emulsion A prepared in Example 1 was chemically sensitized with 5.0 mg of sodium thiosulfate, 0.2 mg of chloroauric acid, and the following compound. A new organic fatty acid silver emulsion was prepared using the silver emulsion. Example 1
An emulsion layer coating liquid, a surface protective layer coating liquid, and a backing layer coating liquid were prepared in the same manner as in 1. above, and coating samples were prepared and evaluated. The same effects as in Example 1 were confirmed.

[0064]

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[0065]

EFFECTS OF THE INVENTION According to the embodiment of the present invention, the fog after the thermo is small and the heat resistance is good.

Claims (3)

[Claims] 1. A photothermographic material comprising, on at least one surface of a support, at least one photosensitive layer containing silver halide emulsion grains, a reducible non-photosensitive silver source and a silver reducing agent. A photothermographic material, wherein the photosensitive material has a layer containing a polymer containing chlorinated polypropylene and contains phthalazine. 2. The photothermographic material according to claim 1, wherein the layer containing a polymer containing chlorinated polypropylene is a non-photosensitive layer provided at a position farther from the support than the photosensitive layer. 3. The photothermographic material according to claim 1, wherein the layer containing a polymer containing chlorinated polypropylene is a surface protective layer.