JP2003322925A - Photothermographic imaging material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photothermographic imaging material excellent in antistatic performance without deteriorating visible light transmittance and excellent also in fog, sensitivity, raw stock preservability, light resistance and silver tone. <P>SOLUTION: In the photothermographic imaging material having a photosensitive layer comprising photosensitive silver halide grains, an organic silver salt, a reducing agent and a binder on a support and a photosensitive layer protecting layer on the photosensitive layer and having a back coating layer on a side of the support opposite to the side with the photosensitive layer, a dendrimer compound having π electron conjugated systems linked by a nitrogen or oxygen atom is contained. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photothermographic image forming material for forming an image by post-exposure heat development, and more specifically, it has excellent antistatic property without deterioration of visible light transmittance, and also has fog, sensitivity, The present invention relates to a photothermographic image forming material excellent in raw storage stability, light resistance and silver tone.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of environmental protection and workability in the medical field, there has been a strong demand for a photographic material capable of forming an image by light or heat treatment which does not generate waste liquid associated with a wet process, and particularly, both of light and heat are required. A technique relating to a photothermographic material for photographic technology, which is capable of forming a clear black image with high resolution by utilizing development, has been commercialized and rapidly spread. Since these photothermographic materials are usually developed at a temperature of 80 ° C. or higher, they are called photothermographic image forming materials, which are distinguished from conventional wet photosensitive materials which are liquid-developed in the range of 25 ° C. to 45 ° C.

Conventionally, this type of photothermographic image-forming material has a problem that it is liable to be charged with static electricity due to friction and peeling, and static marks and dust, which are image defects, are easily attached. The solution has been to apply inorganic fine particles such as conductive tin oxide or indium oxide between the support and the photosensitive layer. However, this method needs to contain fine particles to a density at which the fine particles come into contact with each other in order to obtain conductivity, and if the fine particles are contained to this density, the film strength is deteriorated. Although the problem has been solved by using a tough binder or a crosslinkable hardener to strengthen the film strength, it was difficult to obtain satisfactory performance.

On the other hand, the use of organic conductive polymers has been studied, but in all cases, there is no suitable solvent for dissolving the polymer, and thus it is difficult to apply, and light absorption of the π-electron conjugated system. Therefore, it is difficult to put into practical use due to the drawbacks such as easy coloring. Especially in the case of photothermographic imaging materials,
Since a reducing agent and an organic silver salt are contained as essential components in addition to the photosensitive silver halide, it is easy to fog, it is difficult to obtain high sensitivity, and raw storage stability, light resistance and silver tone are easily deteriorated. It was difficult to select a suitable antistatic agent because there was a problem to be solved. For fogging, Japanese Patent Laid-Open No. 5
7-643, JP-A-5-341432, 11-2.
As disclosed in JP-A No. 95846 and JP-A No. 2000-206642, examples using a disulfide compound are disclosed, but the fog-inhibiting effect is not sufficient, and there is a technique using a hydrazide compound for sensitivity. Fog tends to be high and is not sufficiently satisfied. For silver tones, a phthalazine compound or a derivative of a phthalic acid compound has been developed, but no good one has been found because its storage stability is likely to deteriorate. Examples of using dendrimer compounds are disclosed in JP-A Nos. 2000-66482 and 2000.
No. 187346, it is an example of using it as a charging member for electrophotography or a photoconductor, and its purpose and constitution are different from those of the present invention.

[0005]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to provide excellent antistatic property without deterioration of visible light transmittance, as well as excellent fog, sensitivity, raw storage stability, light resistance and silver tone. It is to provide a photothermographic image forming material.

[0006]

The above object of the present invention can be achieved by the following constitutions.

1. Photosensitive silver halide grains on a support,
Photothermographic image formation having a photosensitive layer containing an organic silver salt, a reducing agent and a binder, a photosensitive layer protective layer on the photosensitive layer, and a back coating layer on the side of the support opposite to the side having the photosensitive layer. A photothermographic image-forming material, comprising a dendrimer compound having a π-electron conjugated system connected by nitrogen atoms or oxygen atoms.

2. 2. The photothermographic image-forming material as described in 1 above, wherein the dendrimer compound having a π-electron conjugated system connected by a nitrogen atom or an oxygen atom is a compound represented by the general formula (1).

3. 3. The photothermographic image-forming material as described in 1 or 2 above, which contains a dendrimer compound and a thiuronium compound having a π-electron conjugated system connected by the nitrogen atom or the oxygen atom.

4. 1 to 3 characterized by containing a dendrimer compound and a hydrazine compound having a π-electron conjugated system connected by the nitrogen atom or the oxygen atom.
The photothermographic image forming material described in any one of 1.

5. The above-mentioned 1 containing a dendrimer compound and a polyhalomethane compound having a π-electron conjugated system connected by the nitrogen atom or the oxygen atom.
Alternatively, the photothermographic image-forming material as described in 2 above.

6. 3. The photothermographic image-forming material as described in 1 or 2 above, which contains a dendrimer compound and a disulfide compound having a π-electron conjugated system connected by a nitrogen atom or an oxygen atom.

7. 3. The photothermographic image-forming material as described in 1 or 2 above, which contains a dendrimer compound and a phthalazine compound each having a π-electron conjugated system connected by a nitrogen atom or an oxygen atom.

8. 3. The photothermographic image-forming material as described in 1 or 2 above, which contains a dendrimer compound and a phthalic acid compound having a π-electron conjugated system connected by the nitrogen atom or the oxygen atom.

The present invention will be described in detail below. The photothermographic image-forming material of the present invention has a photosensitive layer containing photosensitive silver halide grains, an organic silver salt, a reducing agent and a binder on a support and a photosensitive layer protective layer on the photosensitive layer. The body has a back coating layer on the side opposite to the side having the photosensitive layer, and preferably has a layer structure of at least two layers having a photosensitive layer and a photosensitive layer protective layer on one side of the support. A back coating layer (BC layer) and a protective layer for the BC layer are provided on the side of the body opposite to the side having the photosensitive layer. The photosensitive layer contains at least photosensitive silver halide grains which may be sensitized, an organic silver salt serving as a silver source, a reducing agent and a binder for developing the silver salt to form a silver image. . The dendrimer compound having a π-electron conjugated system linked by a nitrogen atom or an oxygen atom according to the present invention (hereinafter also simply referred to as a dendrimer compound according to the present invention) is preferably used in the photosensitive layer protective layer, It may be added to an intermediate layer adjacent to the photosensitive layer, an undercoat layer, or the like, or may be added to a layer through the intermediate layer. Preferred examples of the dendrimer compound according to the present invention include compounds represented by the general formula (1) or (2).

In the general formula (1) or (2),
R ¹ represents an atomic group having a π-electron conjugated system, n is 1 to
Represents an integer of 3. However, 2 ^n-2 , 2 ^n-3 n-2, n-3
When becomes negative, it is assumed that 2 ^n-2 = 0 and 2 ^n-3 = 0.

Examples of the group of atoms having a π-electron conjugated system represented by R ¹ include a benzene ring group, a biphenyl ring group, a thiophene ring group, a furan ring group, and a dipyridyl ring group which may have a substituent. Can be mentioned. Substituents on the ring group include an alkyl group (eg, methyl group, ethyl group, butyl group, octyl group, etc.), hydroxy group, alkoxy group (methoxy group, ethoxy group, butoxy group, etc.), cyano group, amino group Etc. can be mentioned.

N represents an integer of 1 to 3. When n exceeds 3, haze may increase, which is not preferable.

The dendrimer compound according to the present invention can be used alone or in combination with the following compounds. Examples of the compound that is preferably used in combination include a thiuronium compound, a hydrazine compound, a polyhalomethane compound, a disulfide compound, a phthalazine compound, and a phthalic acid compound. The amount used in combination is 1 mol based on 1 mol of the dendrimer compound according to the present invention. It is preferable to use in combination with addition of × 10 ^-8 mol to 1 × 10 ³ mol. The method of addition is dissolution or fine particles in water, alcohols (eg, methanol, ethanol, isobutyl alcohol, etc.), ketones (eg, acetone, methyl ethyl ketone, isobutyl ketone, etc.), aromatic organic solvents (eg, toluene, xylene, etc.). It can be dispersed and added. The average particle size when fine particles are dispersed is 1 to 300 nm.
Is preferred. Preferred specific examples of the dendrimer compound according to the present invention are shown below.

The dendrimer compound according to the present invention is
It can be synthesized with reference to Japanese Patent Publication Nos. 8-512345 and 9-512264.

[0021]

[Chemical 2]

[0022]

[Chemical 3]

[0023]

[Chemical 4]

[0024]

[Chemical 5]

[0025]

[Chemical 6]

[0026]

[Chemical 7]

[0027]

[Chemical 8]

[0028]

[Chemical 9]

[0029]

[Chemical 10]

The thiuronium compound, hydrazine compound, polyhalomethane compound, disulfide compound, cross-linking agent, phthalazine compound and phthalic acid compound used in combination with the dendrimer compound according to the present invention will be described in detail in order.

(Thiuronium Compound) As the thiuronium compound used in the present invention, an imidazole group, an oxazole group, a thiazole group, a benzoxazole group, a benzthiazole group, a benzimidazole group or the like is added to the sulfur atom of thiourea as an alkylene group (for example, Methylene group,
Those bonded via an ethylene group and a propylene group) are preferred. Addition amount is 1 mg to 10 g per 1 square meter
Is preferable, and 10 mg to 500 mg is particularly preferable. Preferred specific examples are shown below, but the present invention is not limited thereto.

[0032]

[Chemical 11]

(Hydrazine Compound) The hydrazine compound used in the present invention is preferably a compound having a —NHNH—CO— bond. Addition amount is 1m per 1 square meter
g to 10 g is preferable, and 10 mg to 600 mg is particularly preferable. As for the timing of addition, it may be added during chemical sensitization,
It may be added at any time after chemical sensitization and immediately before coating. Preferred specific examples are shown below, but the present invention is not limited thereto.

[0034]

[Chemical 12]

(Polyhalomethane Compound) The polyhalomethane compound used in the present invention is a compound having a polyhalomethyl group, wherein the polyhalomethyl group is an aromatic group (eg, phenyl group, naphthyl group and chlorophenyl group) or a heterocyclic group (eg, pyridyl group). Group, a furyl group, an imidazolyl group and an oxazolyl group) are preferably bonded directly or via a linking group. Preferred linking groups, -CO- _{group, -SO 2 -, - NHSO 2} -
Etc. can be mentioned. Examples of the polyhalomethyl group include a trimethylbromo group, a trichloromethyl group and a dibromomethyl group. The amount of addition is preferably 1 mg to 10 g per square meter, and particularly 10 mg to 400 mg.
Is preferred. Preferred specific examples are shown below, but the present invention is not limited thereto.

[0036]

[Chemical 13]

(Disulfide Compound) Examples of the disulfide compound used in the present invention include an alkyl group (eg, methyl group, ethyl group, propyl group and octyl group) at both ends of a disulfide group, an aromatic group (phenyl group, chlorophenyl group). , P-methylphenyl group and naphthyl group) or a heterocyclic group (for example, pyridyl group, furyl group, imidazolyl group, oxazolyl group and triazole group) are preferred. The amount of addition is preferably 1 mg to 10 g per square meter, particularly 10 mg to 5
00 mg is preferred. Preferred specific examples are shown below,
The present invention is not limited to these.

[0038]

[Chemical 14]

(Phthalazine) The phthalazine compound used in the present invention includes phthalazine 3,4,5,6,7.
And / or it may have a substituent at the 8-position. As a preferred substituent, an alkyl group (eg, methyl group, ethyl group, propyl group, octyl group, etc.), aromatic group (phenyl group, chlorophenyl group, p-methylphenyl group, naphthyl group, etc.) or heterocyclic group (eg, Pyridyl group, furyl group, imidazolyl group, oxazolyl group and triazole group) are preferably bonded. The amount of addition is preferably 1 mg to 10 g per square meter, and particularly 1
0 mg to 500 mg is preferable. Preferred specific examples are shown below, but the present invention is not limited thereto.

[0040]

[Chemical 15]

(Phthalic Acid Compound) The phthalic acid compound used in the present invention is preferably one having a substituent at the 3, 4, 5 and / or 6-position of orthophthalic acid. Preferred substituents are halogen atoms (eg, fluorine atom, chlorine atom, etc.), alkyl groups (eg, methyl group, ethyl group, propyl group, octyl group, etc.), alkoxy groups (eg, methoxy group, ethoxy group, isopropyl group). , N-propyl group, n-butyl group, etc.), carboxyl group, aromatic group (phenyl group, chlorophenyl group, p-methylphenyl group, naphthyl group, etc.) or heterocyclic group (eg pyridyl group, furyl group, imidazolyl group) Groups, oxazolyl groups, triazole groups, etc.) are preferred. Addition amount is 1 mg to 10 g per 1 square meter
Is preferable, and 10 mg to 500 mg is particularly preferable. Preferred specific examples are shown below, but the present invention is not limited thereto.

[0042]

[Chemical 16]

(Photosensitive Silver Halide Grain) The photosensitive silver halide grain contained in the photosensitive layer of the photothermographic image forming material of the present invention comprises a silver halide forming component obtained by a single jet or double jet method. By mixing by any method known in the technical field, it can be prepared in advance by any method such as an ammonia method emulsion, a neutral method and an acidic method. The photosensitive silver halide grains preferably have a small grain size in order to suppress white turbidity after image formation to a low level and to obtain good image quality. The average particle size is usually 0.1 μm or less, preferably 0.01 to 0.1 μm,
It is particularly preferably 0.02 to 0.08 μm. The shape of the photosensitive silver halide grains is not particularly limited,
There are so-called normal crystals such as cubic and octahedron, and non-normal crystals such as spherical particles, rod-shaped particles, and tabular particles. The silver halide composition is also not particularly limited and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide and silver iodide.

The amount of the photosensitive silver halide grains used is usually 50% by mass or less, preferably 25 to 0.1% by mass, based on the total amount of the photosensitive silver halide grains and the organic silver salt described below.
More preferably, it is between 15 and 0.1% by mass. A part of the organic silver salt can be converted into a photosensitive silver halide grain by using the above-mentioned silver halide-forming component, but various conditions such as reaction temperature, reaction time, reaction pressure and the like of the step are the purpose of preparation. It is preferable that the reaction temperature is −23 ° C. to 74 ° C., the reaction time is 0.1 second to 72 hours, and the reaction pressure is atmospheric pressure.

The photosensitive silver halide grains prepared by the above-mentioned various methods are chemically sensitized with, for example, a sulfur-containing compound, a gold compound, a platinum compound, a palladium compound, a silver compound, a tin compound, a chromium compound or a combination thereof. can do. The method and procedure of this chemical sensitization are described in, for example, U.S. Pat. No. 4,036,650, British Patent 1,518,850, and Japanese Patent Laid-Open No. 51-2243.
0, 51-78319, 51-81124 and the like.

The photosensitive silver halide grains used in the present invention can be sensitized with a spectral sensitizing dye, if necessary.
For example, JP-A-63-159841 and JP-A-60-1403.
No. 35, No. 63-231437, No. 63-25965.
No. 1, No. 63-304242, No. 63-15245
No. 4,639,414 and 4,743.
0,455, 4,741,966, 4,7
The sensitizing dyes described in Nos. 51,175 and 4,835,096 can be used. Useful sensitizing dyes for use in the present invention are, for example, Research Dis
Closure 17643 IV-A (1978 1
February p. 23) and Item 1831X (p.437, August 1978) or cited therein. In particular, a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of various scanner light sources can be advantageously selected. For example, JP-A-9-34078 and JP-A-9-54409.
Nos. 9-80679 are preferably used.

(Organic Silver Salt) The organic silver salt contained in the photothermographic image-forming material of the present invention is a reducible silver source and contains an organic acid, a heteroorganic acid and an acid polymer containing a reducible silver ion source. The silver salt and the like are used. Also, the ligand is
Organic or inorganic silver salt complexes having a total stability constant for silver ions of 4.0 to 10.0 are also useful. An example of silver salt is
Research Disclosure 1702
9 and 29963, including:
Silver salts of organic acids (eg, gallic acid, oxalic acid, behenic acid, stearic acid, palmitic acid, lauric acid, and other silver salts) and the like. The organic silver salt is prepared by mixing the alkali metal salt of the above organic acid and silver nitrate, but may be added by a controlled double jet method at the time of mixing, or may be added at a different timing. It may be added all at once to the arbitrary step of forming a silver salt or in several steps.

(Reducing Agent) Examples of preferable reducing agents contained in the photothermographic image-forming material of the present invention are described in US Pat.
70,448, 3,773,512, 3,59
No. 3,863, etc. and Research Discros
ure 17029 and 29963,
These include: (KG1) 1,1-bis (2-hydroxy-3,5-
Dimethylphenyl) -3,5,5-trimethylhexane (KG2) Bis (2-hydroxy-3-t-butyl-)
5-Methylphenyl) methane (KG3) 2,2-bis (4-hydroxy-3-methylphenyl) propane (KG4) 4,4-ethylidene-bis (2-t-butyl-6-methylphenol) (KG5) 2,2-Bis (3,5-dimethyl-4-hydroxyphenyl) propane The compound shown above can be used by being dispersed in water or dissolved in an organic solvent. As the organic solvent, alcohols such as methanol and ethanol; ketones such as acetone and methyl ethyl ketone; aromatic solvents such as toluene and xylene can be arbitrarily selected and used. The amount of reducing agent used is usually 1 × 10 ^-2 to 1 mol of silver.
It is 10 mol, preferably 1 × 10 ^{-2 to} 1.5 mol.

(Binder) The binder used in the present invention, that is, the polymer binder used in the photosensitive layer or the non-photosensitive layer of the photothermographic image-forming material of the present invention, is polyvinyl butyral, polyacrylamide, polystyrene, Examples thereof include polyvinyl acetate, polyurethane, polyacrylic acid ester, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, vinyl chloride-vinyl acetate copolymer, styrene-butadiene-acrylic copolymer. After further drying, after forming a film, it is preferable that the equilibrium water content of the coating film is low, as particularly low water content, for example, cellulose acetate of the organic solvent system, cellulose acetate butyrate and polyacetal. You can The polyacetal preferable for the present invention is preferably polybutyral acetalized with butyraldehyde or polyacetal acetalized with acetaldehyde (polyacetal in a narrow sense). The acetalization theoretically exists from 1% to 100%, but practically 20 to 95% is preferable. If the degree of acetalization is lower than this range, the number of hydroxyl groups will increase, and the photographic performance will show weak characteristics to humidity.If the degree of acetalization is high, the reaction temperature and time will be severely excessive, resulting in cost increase and productivity. Is reduced. The degree of polymerization of the polymer binder, which is the binder used in the present invention, can be freely selected from about 10 to about 10,000, but 100 to 6000 is preferable from the viewpoint of coating properties and productivity during synthesis.

(Crosslinking Agent) The binder can maintain the adhesion to the lower layer and the upper layer and obtain a film strength that is not easily scratched by forming a film alone. It is possible to improve film adhesion and film strength. However, when the cross-linking reaction of the cross-linking agent is slow, the photographic performance is not stable and the storage stability is deteriorated. As the quick-acting and preferable crosslinking agent used in the present invention, a polyfunctional crosslinking agent having at least two isocyanate groups can be mentioned. Preferred crosslinking agents are shown below. (H1) Hexamethylene diisocyanate (H2) Hexamethylene diisocyanate trimer (H3) Tolylene diisocyanate (H4) Phenylene diisocyanate (H5) Xylylene diisocyanate The crosslinking agent is water or alcohol. , Ketones, or non-polar organic solvents, and may be added after being dissolved, or may be added as a solid in the coating liquid. The addition amount is preferably equivalent to the crosslinkable group of the binder, but may be increased up to 10 times or may be decreased up to 1/10 or less.
If the amount is too small, the crosslinking reaction will not proceed, and if it is too large, the unreacted crosslinking agent deteriorates the photographic properties, which is not preferable.

(Dye Used in AH Layer or BC Layer if Necessary) The photothermographic image-forming material of the present invention is provided with a back coating layer (BC layer), and if necessary, an antihalation layer for preventing halation. (AH layer)
The dye that can be used in the AH layer or the BC layer may be any dye that absorbs image exposure light, and a preferable example thereof is JP-A-2-216140.
Nos. 7-13295, 7-11432, and U.S. Pat. No. 5,380,635.

(Support) The support is preferably a support such as polyethylene terephthalate, polyethylene naphthalate or syndiotactic polystyrene.
It is preferably axially stretched or heat-fixed and has a thickness of 50 to 400 μm, which has high optical isotropy and good dimensional stability.

(Image exposure) As an exposure method, Japanese Patent Application Laid-Open No. 9-29242
No. 304869, No. 9-311403 and JP-A-2
Laser exposure can be carried out by the method described in No. 000-10230. For exposure of the photothermographic image forming material of the present invention, it is desirable to use a light source suitable for the color sensitivity imparted to the photosensitive material. For example, when the sensitive material is made to be sensitive to infrared light, it can be applied to any light source in the infrared light range, but the laser power is high and the photosensitive material is transparent. From what you can do,
An infrared semiconductor laser (780 nm, 820 nm) is more preferably used for exposure.

(Heat Developing Device) As a device for developing a photothermographic image forming material, there are disclosed in JP-A-11-65067 and JP-A-11-65067.
The devices described in 1-72897 and 84619 can be used.

[0055]

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

Example 1 << Preparation of Subbed Substrate >> A polyethylene terephthalate support having a thickness of 175 μm was subjected to a corona discharge treatment of 12 W / m ² · min for both surfaces, and one surface thereof was coated with a subbing coating solution a- 1
Is coated to a dry film thickness of 0.6 μm and dried to form an undercoat layer A-1, and the undercoating coating solution b described below is provided on the opposite surface.
-1 was applied so as to have a dry film thickness of 0.6 μm and dried to form an undercoat layer B-1.

<Subbing coating liquid a-1> Butyl acrylate (30% by mass) t-butyl acrylate (20% by mass) Styrene (25% by mass) 2-Hydroxyethyl acrylate (25% by mass) copolymer latex liquid (Solid content 30%) is diluted 15 times.

<Subbing coating solution b-1> Butyl acrylate (40% by mass) Styrene (20% by mass) Glycidyl acrylate (40% by mass) Copolymer latex solution (solid content 30%) is diluted 15 times. .

Subsequently, the undercoat layer A-1 and the undercoat layer B-1
A corona discharge of 12 W / m ² · min was applied to the upper surface of the undercoat layer A-1, and the following undercoating upper layer coating solution a-2 was applied to the undercoating layer A-1 and dried to obtain the undercoating upper layer A-2 (photosensitive layer). (For the layer side), and the undercoating upper layer coating liquid b-2 below was applied and dried on the undercoating layer B-1 to provide the undercoating upper layer B-2 (for the BC layer) having an antistatic function. .

[0060]   <Undercoating upper layer coating liquid a-2>   1: 2 copolymer of styrene and butadiene 0.4g / m²   Butyl acrylate (30% by mass)     t-Butyl acrylate (20 mass%)     Styrene (25% by mass)     2-hydroxyethyl acrylate (20% by mass)     Methacrylic acid (5% by mass)     Copolymer latex liquid (solid content 30%) 0.3 g / m²   Matt particles (silica particles, average particle size 4.6 μm) 0.05 g / m²   Cross-linking agent: hexamethylene diisocyanate 0.1 g / m²   <Undercoat upper layer coating solution b-2>   1: 2 copolymer of styrene and butadiene 0.4g / m²   Butyl acrylate (30% by mass)     t-Butyl acrylate (20 mass%)     Styrene (25% by mass)     2-hydroxyethyl acrylate (20% by mass)     Methacrylic acid (5% by mass)     Copolymer latex liquid (solid content 30%) 0.3 g / m²   Matt particles (fine silica particles, average particle diameter 3.2 μm) 0.05 g / m²   Cross-linking agent: hexamethylene diisocyanate 0.1 g / m² << Preparation of Organic Silver Salt A >> Preparation of silver halide grain emulsion A
Then, using this, an organic silver salt A was prepared. <Preparation of silver halide grain emulsion A>
Dissolve 7.5 g of nato gelatin and 10 mg of potassium bromide
After unraveling and adjusting the temperature to 28 ° C and pH to 3.0, silver nitrate
Molar ratio of 370 ml aqueous solution containing 74 g and (98/2)
PAg of an aqueous solution containing potassium bromide and potassium iodide
Controlled double jet method while keeping at 7.7
Added over 10 minutes. In sync with the addition of silver nitrate
1 × 10 sodium salt of sachloroiridium ^-6Mol /
1 mol of silver was added. Then 4-hydroxy-6-methyl
Add 0.3g of -1,3,3a, 7-tetrazaindene
Then adjust the pH to 5 with NaOH and average particle size 0.0
36 μm, variation coefficient of projected diameter area 8%, [100] plane
Halogenated containing cubic silver iodobromide grains in proportion 87%
A silver particle emulsion was obtained. Using a gelatin flocculant in this emulsion
After coagulation and sedimentation and desalination, add water to finish to 160 ml
Gage. This is designated as silver halide grain emulsion A.

<Preparation of Organic Silver Salt A> 111.4 g of behenic acid, 83.8 g of arachidic acid and 54.9 g of stearic acid were dissolved in 3980 ml of pure water at 80 ° C. Next, while stirring at high speed, a 1.5 molar sodium hydroxide aqueous solution 54
After adding 0.2 ml and 6.9 ml of concentrated nitric acid,
Cooled to 0 ° C. to give a sodium acidate solution. While maintaining the temperature of the above-mentioned sodium salt of an organic acid at 55 ° C., 420 ml of pure water was added to the silver halide grain emulsion A (containing 0.038 mol of silver) and stirred for 5 minutes. Next, 760.6 ml of a 1 mol silver nitrate solution was added over 2 minutes, the mixture was stirred for 20 minutes, and water-soluble salts were removed by filtration. Thereafter, washing with deionized water and filtration were repeated until the electric conductivity of the filtrate reached 2 μS / cm, and finally centrifugal dehydration and drying were performed. This is referred to as organic silver salt A.

<< Preparation of Photothermographic Image-Forming Material >> The following photosensitive layer side coating and BC layer side coating were performed on the above-mentioned undercoated support, and drying was carried out on both the photosensitive layer side and the BC layer side for 4 times.
The photothermographic image-forming material was prepared by carrying out at 5 ° C. for 1 minute.

<Coating on BC layer side> On the back surface side, the following B
A coating solution prepared as a methyl ethyl ketone (MEK) solution so as to have a C layer composition and a BC layer protective layer composition was simultaneously multilayer coated so as to have the following amounts, and dried to form a BC layer and a BC layer protective layer.

<BC Layer Composition> Binder: PVB-1 1.8 g / m ² glycidyltrimethoxysilane 1 × 10 ⁻⁴ mol / m ² Dye: C1 2.2 × 10 ⁻⁵ mol / m ² <BC layer Protective Layer Composition> Binder: PVB-1 1.1 g / m ² Crosslinking agent: H1 1 × 10 ⁻⁴ mol / m ² <Coating on photosensitive layer side> On the photosensitive layer side, the following AH layer composition and photosensitive layer composition The coating solution prepared as a methyl ethyl ketone (MEK) solution so as to have the composition of the photosensitive layer protective layer is simultaneously multi-layered so as to have the following coverages and dried to form an AH layer, a photosensitive layer,
A photosensitive layer protective layer was formed.

<AH Layer Composition> Binder: PVB-1 0.4 g / m ² Dye: C1 1.3 × 10 ⁻⁵ mol / m ² <Photosensitive layer composition> Organic silver salt A Silver amount 1.36 g / m ² m ² binder: PVB-1 2.6 g / m ² crosslinking agent: H 2 2 × 10 ⁻³ mol / m ² spectral sensitizing dye A 1 2 × 10 ⁻⁵ mol / m ² antifoggant-1: pyridinium hydrobromide Perbromide 0.3 mg / m ² Antifoggant-2: Isothiazolone 1.2 mg / m ² Reducing agent: KG1 3 × 10 ⁻⁴ mol / m ² <Photosensitive layer protective layer composition> Binder: Cellulose acetate butyrate 1. 2 g / m ² tetrachlorophthalic anhydride 0.5 g / m ² Dendrimer compound according to the present invention (described in Table 1) 0.6 g / m ²

[0066]

[Chemical 17]

(Photographic properties) Unexposed sample was 48% at 25 ° C.
After being stored in an atmosphere of relative humidity for 3 days, it was exposed with a 810 nm sensitometer for semiconductor laser exposure.
After heating at ℃ for 8 seconds, the fog and sensitivity of the obtained sample were determined. Laser exposure was set in double mode with an incident angle of 76 degrees.

(Fog) Using a Macbeth densitometer, the fog value was measured by setting the optical density of the undercoated support to zero.

(Sensitivity) The reciprocal of the exposure amount that gives an optical density of 0.3 is obtained as the sensitivity, and is shown as a relative value with the sensitivity of Sample 101 being 100.

(Raw storability) The unexposed sample was 80% at 35 ° C.
After being stored in an atmosphere of relative humidity for 7 days, it was exposed with a 810 nm sensitometer for semiconductor laser exposure.
After heating at ℃ for 8 seconds, the fog of the obtained sample was determined. Laser exposure was set in double mode with an incident angle of 76 degrees.

(Antistatic property) After leaving the unexposed sample in a room at 20 ° C. and 20% relative humidity for 18 hours, the sample was rubbed with a synthetic fiber cloth (60% nylon, 40% polyester) 5 times,
This was held over 100 styrene beads (average particle diameter 3 mm) (approaching distance 15 mm), and the degree of bead adsorption was evaluated according to the following criteria.

[0072] 5: The number of adsorbed beads is 0 4: The number of adsorbed beads is 1-8 3: Number of adsorbed beads is 9 to 15 2: The number of adsorbed beads is 16 to 25 1: The number of adsorbed beads is 26 or more The results are shown in Table 1.

[0073]

[Table 1]

From Table 1, it can be seen that when the dendrimer compound according to the present invention is used, excellent antistatic property is obtained, fog is low, and sensitivity is high. Further, it can be seen that the raw storability is also excellent.

Example 2 A sample was prepared in the same manner as in Example 1, except that 86 mg each of the dendrimer compound, the thiuronium compound and the hydrazine compound according to the present invention were applied per 1 square meter of the sample. A coating liquid for the photosensitive layer protective layer was prepared. The thiuronium compound and the hydrazine compound were added next to the dendrimer compound according to the present invention.

The results are shown in Table 2.

[0077]

[Table 2]

From Table 2, it can be seen that when the dendrimer compound and the thiuronium compound or the hydrazine compound according to the present invention are added, excellent antistatic properties are obtained, and low fog, high sensitivity and good raw storage stability are obtained.

Example 3 A sample was prepared in the same manner as in Example 1, except that 1
A coating solution was prepared by adding 68 mg of each of the dendrimer compound and the polyhalomethane compound according to the present invention per square meter to the photosensitive layer protective layer. The polyhalomethane compound was added next to the dendrimer compound according to the present invention.

The light resistance was determined as follows. (Light resistance) The sample was allowed to stand on a Schaukasten of 1000 lux for 10 hours, and the optical fog value at that time was measured using a Macbeth densitometer.

The results are shown in Table 3.

[0082]

[Table 3]

From Table 3, it can be seen that when the dendrimer compound and the polyhalomethane compound according to the present invention are added, excellent antistatic properties are obtained, and low fog, high sensitivity and good light resistance are obtained.

Example 4 A sample was prepared in the same manner as in Example 1, except that 78 mg each of the dendrimer compound and the disulfide compound according to the present invention was added per 1 square meter of the sample to prepare a coating solution for the photosensitive layer protective layer. did. The disulfide compound was added next to the dendrimer compound according to the present invention.

The results are shown in Table 4.

[0086]

[Table 4]

From Table 4, it can be seen that when the dendrimer compound and disulfide compound according to the present invention are added, excellent antistatic property is obtained, and low fog, high sensitivity and good raw preservation property are obtained.

Example 5 A sample was prepared in the same manner as in Example 1, except that 56 mg of the dendrimer compound according to the present invention and 56 mg of phthalazine were added to each square meter of the sample. Was prepared. Phthalazine was added next to the dendrimer compound according to the present invention.

The silver tone was evaluated as follows. (Silver color tone) The samples after heat development were arranged on a Schaukasten, and the color tone of the silver image was visually evaluated using the following criteria as a guide.

5: Black and best without yellowing 4: Color tone slightly other than black is seen 3: Color tone other than black is slightly seen but practically no problem Level 2: Clearly color tone other than black Is observed, and the color tone is inferior and practically useless 1: Table 5 shows the result in which the color tone other than black is strongly observed and the color tone is the worst.

[0091]

[Table 5]

From Table 5, it is understood that when the dendrimer compound and the phthalazine compound according to the present invention are added, excellent antistatic property is obtained, and low fog, high sensitivity and good color tone are obtained.

Example 6 A sample was prepared in the same manner as in Example 5, except that 73 mg each of the dendrimer compound according to the present invention and phthalic acid was added per 1 square meter of the sample to prepare a coating solution for the photosensitive layer protective layer. did. Phthalic acid was added next to the dendrimer compound according to the invention. The results are shown in Table 6.

[0094]

[Table 6]

From Table 6, it can be seen that when the dendrimer compound and phthalic acid according to the present invention are added, excellent antistatic properties are obtained, and low fog, high sensitivity and good raw storage stability are obtained.

[0096]

According to the present invention, the antistatic property is excellent without deterioration of the visible light transmittance, and the fog, sensitivity, raw storability,
It is possible to provide a photothermographic image forming material having excellent light resistance and silver tone.

Claims (8)

[Claims] 1. A photosensitive layer containing a photosensitive silver halide grain, an organic silver salt, a reducing agent and a binder on a support, and a photosensitive layer protective layer on the photosensitive layer. A photothermographic image forming material having a back coating layer on the side opposite to the side having a dendrimer compound having a π-electron conjugated system linked by nitrogen atoms or oxygen atoms. 2. The dendrimer compound having a π-electron conjugated system connected by a nitrogen atom or an oxygen atom is a compound represented by the following general formula (1) or (2). Photothermographic image forming materials. [Chemical 1] (In the formula, R ¹ represents an atomic group having a π-electron conjugated system, and n
Represents an integer of 1 to 3. However, 2 ^n-2 , 2 ^n-3 n-
When 2 and n-3 are negative, it is assumed that 2 ^n-2 = 0 and 2 ^n-3 = 0. ) 3. The photothermographic image-forming material according to claim 1, which contains a dendrimer compound and a thiuronium compound having a π-electron conjugated system linked by the nitrogen atom or the oxygen atom. 4. A dendrimer compound and a hydrazine compound having a π-electron conjugated system connected by the nitrogen atom or the oxygen atom are contained.
The photothermographic image forming material described in any one of 1. 5. A dendrimer compound and a polyhalomethane compound having a π-electron conjugated system connected by the nitrogen atom or the oxygen atom are contained.
Alternatively, the photothermographic image-forming material as described in 2 above. 6. The photothermographic image-forming material according to claim 1 or 2, which contains a dendrimer compound and a disulfide compound having a π-electron conjugated system connected by a nitrogen atom or an oxygen atom. 7. The photothermographic image-forming material according to claim 1 or 2, which contains a dendrimer compound and a phthalazine compound having a π-electron conjugated system connected by a nitrogen atom or an oxygen atom. 8. The photothermographic image-forming material according to claim 1, which contains a dendrimer compound and a phthalic acid compound having a π-electron conjugated system connected by a nitrogen atom or an oxygen atom.