JP2000098531A - Image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image forming method using a heat developable photosensitive material by which excellent photographic characteristics can be obtd. and constant photographic characteristics can be always obtd. regardless to differences in environmental conditions during treatment, by controlling the difference of humidity between the ones when the photosensitive material is exposed and when the material is heat developed. SOLUTION: A heat developable photosensitive material containing org. silver salts, a reducing agent for silver ion, a polymer binder and photosensitive silver halides on a supporting body is imagewise-exposed and heat developed to form an image. In this process, the difference of humidity between the ones when the photosensitive material is exposed and when the material is heat developed is controlled to <=20%RH. The photosensitive silver halides contain an iridium compd. and are chemically sensitized. It is required that the exposure and development are carried out in the environment with <=20%RH difference of humidity between humidity at exposure time and that at development time, preferably <=15%RH. To satisfy the conditions above described, the exposure machine and the developing machine are separated from each other, and humidity is independently controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming method using a photothermographic material (hereinafter sometimes referred to as a photothermographic material).

[0002]

2. Description of the Related Art In recent years, there has been a strong demand in the medical field to reduce the amount of waste liquid from the viewpoint of environmental protection and space saving.
Therefore, a laser imagesetter or laser
There is a need in the art for photothermographic materials for medical diagnostic and photographic applications that can be exposed more efficiently by an imager and can form sharp black images with high resolution and sharpness. ing. These photothermographic materials can eliminate the use of solution processing chemicals and provide a simpler and more environmentally friendly thermal development system to customers.

[0003] Although there is a similar demand in the field of general image forming materials, medical images require high-quality images with excellent sharpness and granularity due to the need for fine depiction. From the viewpoint, there is a feature that a cool tone image is preferred. At present, various hard copy systems using pigments and dyes, such as ink jet printers and electrophotographs, are distributed as general image forming systems, but none of them are satisfactory as output systems for medical images.

On the other hand, a thermal image forming system using an organic silver salt is disclosed in many documents including US Pat. No. 2,910,377 and Japanese Patent Publication No. 43-4924. The thermal image forming system using these organic silver salts can achieve image quality and color tone that are satisfactory as medical images.

However, these thermal image forming systems are different from solution-based developing processes using a developing solution or the like, and are developed only by heating during processing. There is a problem that it will.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming method using a photothermographic material which is excellent in photographic characteristics and which can always obtain constant photographic characteristics even when environmental conditions during processing are different. Is to provide.

[0007]

This object has been achieved by the following means. (1) A method for forming an image by imagewise exposing a photothermographic material containing an organic silver salt, a reducing agent for silver ions, a polymer binder and a photosensitive silver halide on a support, followed by heat development to form an image, An image forming method, wherein the difference between the humidity at the time of exposing the photosensitive material and the humidity at the time of thermal development is 20% RH or less.

(2) The image forming method according to (1), wherein the photosensitive silver halide contains an iridium compound and is chemically sensitized.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The photothermographic material of the present invention may be heat-developed by any method, but the preferred development temperature is 80 to 250 ° C, more preferably 100 to 140 ° C. The development time is preferably from 1 to 180 seconds, more preferably from 10 to 90 seconds.

The light-sensitive material of the present invention may be exposed by any method, but a laser beam is preferred as an exposure light source.
As the laser beam according to the present invention, gas laser, YAG
Lasers, dye lasers, semiconductor lasers and the like are preferred. Further, a semiconductor laser and a second harmonic generation element can be used. The light-sensitive material of the present invention has a low haze at the time of exposure and tends to generate interference fringes. As this interference fringe generation prevention technology, a technology disclosed in Japanese Patent Application Laid-Open No. 5-113548 or the like, in which a laser beam is obliquely incident on a photosensitive material, or a multi-mode laser disclosed in WO95 / 31754 or the like is used. There are known methods for performing these methods, and it is preferable to use these techniques. To expose the photosensitive material of the present invention, SPIE vol.169 Laser Printing pages 116-128 (197
9), it is preferable to expose the laser beams so as to overlap each other so as to make the scanning lines invisible, as disclosed in JP-A-4-51043 and WO95 / 31754.

The exposure and development processing method of the present invention comprises:
Any of the above combinations may be used, but the treatment must be performed in an environment where the difference between the humidity at the time of exposure and the humidity at the time of development is 20% RH or less, preferably 15% RH or less. In order to satisfy such conditions, the exposure machine and the developing machine are separated and the humidity is controlled independently of each other, or the exposure machine and the developing machine are configured to easily take in the outside air and used under the same environment. May be taken. Regarding the absolute humidity in the exposure and the development, the treatment may be performed at any humidity as long as the exposure machine and the developing machine are out of order so as not to affect the others.

The photosensitive silver halide used in the present invention is not particularly limited as a halogen composition, and silver chloride, silver chlorobromide, silver bromide, silver iodobromide, and silver iodochlorobromide can be used. . The distribution of the halogen composition in the grains may be uniform, the halogen composition may change stepwise, or may change continuously. Further, silver halide grains having a core / shell structure can be preferably used. The preferred structure is
The core has a double / five-layer structure, and more preferably has a double / four-layer structure.
Shell particles can be used. A technique for localizing silver bromide on the surface of silver chloride or silver chlorobromide grains can also be preferably used.

Methods of forming light-sensitive silver halide are well known in the art, for example, Research Disclosure No. 17029, June 1978, and US Pat. No. 3,700,458.
Can be used.Specifically, a photosensitive silver halide is prepared by adding a silver-supplying compound and a halogen-supplying compound to gelatin or another polymer solution, and then the organic silver halide is added. A method of mixing with a silver salt is used. The grain size of the photosensitive silver halide is preferably small for the purpose of suppressing white turbidity after image formation, specifically, 0.20 μm or less, more preferably 0.01 μm or less.
μm or more and 0.15 μm or less, more preferably 0.02 μm or more and 0.12
μm or less is preferred. Here, the grain size means the length of the edge of the silver halide grain when the silver halide grain is a cubic or octahedral so-called normal crystal. Also,
In the case where the silver halide grains are tabular grains, the diameter means a diameter when converted into a circular image having the same area as the projected area of the main surface.
In the case of other than normal crystals, for example, in the case of spherical grains, rod-shaped grains, etc., it refers to the diameter of a sphere equivalent to the volume of silver halide grains.

The shape of the silver halide grains is cubic,
Octahedral, tabular particles, spherical particles, rod-like particles, potato-like particles and the like can be mentioned. In the present invention, cubic particles and tabular particles are particularly preferable. When the tabular silver halide grains are used, the average aspect ratio is preferably from 100: 1 to 2: 1, more preferably from 50: 1 to 3: 1. Further, grains having rounded corners of silver halide grains can also be preferably used. The surface index (mirror index) of the outer surface of the photosensitive silver halide grains is not particularly limited. preferable. The ratio is preferably at least 50%, more preferably at least 65%, even more preferably at least 80%. Miller index ｛100
The ratios of the｝ faces are the ｛111｝ face and ｛1
00 T. Tani; J. Imaging Sc
i., 29, 165 (1985).

The photosensitive silver halide grains of the present invention contain a metal or metal complex of Group VII or VIII of the periodic table. Rhodium, rhenium, ruthenium, osnium and iridium are preferably the metals of Group VII or VIII of the periodic table or the central metal of the metal complex. In particular, iridium compounds are preferably used for the purpose of the present invention. One kind of these metal complexes may be used, or two or more kinds of complexes of the same metal and different metals may be used in combination. The structure of a specific metal complex is described in JP-A-7-225449.
And the like.

Various compounds can be used as the iridium compound used in the present invention, and examples thereof include hexachloroiridium, hexaammineiridium, trioxalatoiridium, hexacyanoiridium, and pentachloronitrosyliridium. These iridium compounds are used after being dissolved in water or a suitable solvent. However, a method generally used for stabilizing a solution of the iridium compound, that is, an aqueous solution of hydrogen halide (for example, hydrochloric acid, hydrobromic acid, hydrofluoric acid) is used. Etc.) or a method of adding an alkali halide (eg, KCl, NaCl, KBr, NaBr, etc.). Instead of using water-soluble iridium, it is also possible to add and dissolve another iridium-doped silver halide grain during silver halide preparation. The addition amount of these iridium compounds is 1 × 10 ⁻⁷ mol to 1 × per mol of silver halide.
The range is preferably 10 ^-3 mol, particularly preferably 1 x 10 ^-5 mol to 1 x 10 ^-3 mol.

As the rhodium compound used in the present invention, a water-soluble rhodium compound can be used. For example, a rhodium (III) halide compound or a rhodium complex salt having a ligand such as halogen, amines, oxalato, etc., for example, hexachlororhodium (III)
Complex salt, pentachloroacolodium (III) complex salt, tetrachlorodiachodium (III) complex salt, hexabromorhodium
(III) complex salts, hexaammine rhodium (III) complex salts, and trizalatrodium (III) complex salts. These rhodium compounds are used by dissolving them in water or a suitable solvent. A method generally used for stabilizing a solution of a rhodium compound, that is, an aqueous hydrogen halide solution (for example, hydrochloric acid, hydrobromic acid, hydrofluoric acid) Etc.) or a method of adding an alkali halide (eg, KCl, NaCl, KBr, NaBr, etc.). Instead of using water-soluble rhodium, it is also possible to add and dissolve other silver halide grains doped with rhodium during the preparation of silver halide.

The addition amount of these rhodium compounds is preferably in the range of 1 × 10 ⁻⁸ mol to 5 × 10 ⁻⁶ mol, and particularly preferably in the range of 5 × 10 ⁻⁸ mol to 1 × 10 ⁻⁶ mol per mol of silver halide. Is a mole. These compounds can be appropriately added at the time of the production of silver halide emulsion grains and at each stage before coating the emulsion, but it is particularly preferable to add them at the time of emulsion formation and incorporate them into the silver halide grains. .

Rhenium, ruthenium and osmium used in the present invention are described in JP-A-63-2042 and JP-A-1-285941.
, 2-20852, 2-20855, etc. in the form of a water-soluble complex salt. Particularly preferred is a six-coordinate complex represented by the following formula. [ML ₆ ] ^n- where M represents Ru, Re or Os, L represents a ligand, n
Represents 0, 1, 2, 3 or 4. In this case, the counter ion is not important and ammonium or alkali metal ions are used. Preferred ligands are halide ligands, cyanide ligands, cyanide ligands,
Nitrosyl ligand, thionitrosyl ligand and the like can be mentioned. Examples of specific complexes used in the present invention are shown below, but the present invention is not limited thereto.

[ReCl₆ ]^3-, [ReBr₆]^3-, [ReCl_Five(N
O)]^2-, [Re (NS) Br_Five]^2-, (Re (NO) (CN)_Five]^2-, [Re
(O)_Two(CN)_Four]^3-, [RuCl₆]^3-, [RuCl_Four(H_TwoO)_Two]^-,
(RuCl_Five(H _TwoO))^2-, [RuCl_Five(NO))^2-, [RuBr_Five(NS))
^2-, [Ru (CO)_ThreeCl_Three]^2-, [Ru (CO) Cl _Five]^2-, [Ru (CO) B
r_Five]^2-, [OsCl₆]^3-, [OsCl_Five(NO))^2-, [Os (NO) (C
N)_Five]^{Two -}, (Os (NS) Br_Five]^2-, [Os (O)_Two(CN)_Four]^Four-

The addition amount of these compounds is 1
The range is preferably from 1 × 10 ^-9 mol to 1 × 10 ^-5 mol, and particularly preferably from 1 × 10 ^-8 mol to 1 × 10 ^-6 mol, per mol. These compounds can be appropriately added at the time of the production of silver halide emulsion grains and at each stage before coating the emulsion, but it is particularly preferable to add them at the time of emulsion formation and incorporate them into the silver halide grains. . To add these compounds during the formation of silver halide grains and incorporate them into silver halide grains, powder of metal complex or NaC
l, a method in which an aqueous solution dissolved together with KCl is added to a water-soluble salt or water-soluble halide solution during particle formation, or a third method in which a silver salt and a halide solution are simultaneously mixed.
And a method in which silver halide grains are prepared by a simultaneous three-liquid mixing method, or a method in which a required amount of an aqueous solution of a metal complex is charged into a reaction vessel during grain formation. In particular, a method in which a powder or an aqueous solution dissolved together with NaCl and KCl is added to a water-soluble halide solution is preferable.
For the addition to the particle surface, a required amount of an aqueous solution of a metal complex can be charged into the reaction vessel immediately after the formation of the particles, during or at the end of physical ripening, or at the time of chemical ripening.

The silver halide grains used in the present invention may further include cobalt, iron, nickel, chromium, palladium,
It may contain metal atoms such as platinum, gold, thallium, copper and lead. For compounds of cobalt, iron, chromium, and ruthenium, hexacyano metal complexes can be preferably used. Specific examples include ferricyanate ion, ferrocyanate ion, hexacyanocobaltate ion,
Examples include, but are not limited to, hexacyanochromate ions and hexacyanoruthenate ions. The phase containing the metal complex in the silver halide may be uniform, may be contained in the core at a high concentration, or may be contained in the shell at a high concentration, and there is no particular limitation. The amount of the above metal is preferably 1 × 10 ^-9 to 1 × 10 ^-4 mol per mol of silver halide. Further, in order to incorporate the metal, a metal salt in the form of a single salt, a double salt, or a complex salt can be added at the time of preparing particles.

The photosensitive silver halide grains can be desalted by washing with a method known in the art such as a noodle method or a flocculation method, but in the present invention, they may or may not be desalted. .

The silver halide emulsion of the present invention is preferably subjected to chemical sensitization. Known chemical sensitization methods such as sulfur sensitization, selenium sensitization, tellurium sensitization, gold sensitization, and noble metal sensitization can be used. In particular, a sulfur sensitization method, a selenium sensitization method, and a tellurium sensitization method are preferably used. When used in combination with gold sensitization, for example, sulfur sensitization and gold sensitization, selenium sensitization and gold sensitization, sulfur sensitization and selenium sensitization and gold sensitization, Sulfur sensitization, tellurium sensitization, and gold sensitization, and sulfur sensitization, selenium sensitization, tellurium sensitization, and gold sensitization are preferable.

The sulfur sensitization preferably used in the present invention is
Usually, the emulsion is added at a high temperature of 40 ° C or higher by adding a sulfur sensitizer.
This is performed by stirring for a certain period of time. As a sulfur sensitizer
Known compounds can be used.
In addition to sulfur compounds contained in tin, various sulfur compounds
Thiosulfates, thioureas, thiazoles,
-Danins and the like can be used. Preferred sulfur compounds
The products are thiosulfates and thiourea compounds. Sulfur sensitizer
Depends on the pH, temperature, silver halide grains during chemical ripening.
Changes under various conditions such as the size of silver halide
1 × 10 per mole ^-7~ 1 × 10^-2Mol and more preferred
1x10^-Five~ 1 × 10^-3Is a mole.

As the selenium sensitizer used in the present invention, known selenium compounds can be used. That is, it is usually carried out by adding an unstable and / or non-unstable selenium compound and stirring the emulsion at a high temperature of 40 ° C. or higher for a certain time. As unstable selenium compounds, JP-B-44-15748, JP-B-43-13489, JP-A-4-25832,
The compounds described in JP-A-4-109240, JP-A-3-21798 and the like can be used. In particular, the general formula (VIII) in JP-A-4-324855
It is preferable to use the compound represented by (IX).

The tellurium sensitizer used in the present invention is a compound that forms silver telluride which is presumed to be a sensitizing nucleus on the surface or inside of silver halide grains. The formation rate of silver telluride in a silver halide emulsion is described in JP-A-5-3132.
It can be tested by the method described in No. 84. Examples of tellurium sensitizers include diacyl tellurides, bis (oxycarbonyl) tellurides, bis (carbamoyl) tellurides, diacyl tellurides, bis (oxycarbonyl) ditellurides, bis (carbamoyl) ditellurides, P = Te
Compounds having a bond, tellurocarboxylates, Te-organyltellurocarboxylates, di (poly) tellurides, tellurides, tellurols, telluroacetals, tellurosulfonates, compounds having a P-Te bond,
Te-containing heterocycles, tellurocarbonyl compounds, inorganic tellurium compounds, colloidal tellurium, and the like can be used.
Specifically, U.S. Pat.Nos. 1,623,499 and 3,320,069
No. 3,772,031, UK Patent No. 235,211 and No. 1,12
No. 1,496, No. 1,295,462, No. 1,396,696, Canadian Patent No. 800,958, JP-A-4-204640, JP-A-3-53693,
3-131598, 4-129787, Journal of Chemical Society Chemical Communication (J. Che
m.Soc.Chem.Commun.), 635 (1980), ibid, 1102 (197
9), ibid, 645 (1979), Journal of Chemical Society Parkin Transaction 1 (J. Chem. Soc.
Perkin.Trans.1), 2191 (1980), edited by S. Patai,
The Chemistry of Organic Selenium and Tellurium Campounds
c Serenium and Tellunium Compounds), Vol 1 (1986),
The compounds described in Vol. 2 (1987) can be used.
Particularly, compounds represented by formulas (II), (III) and (IV) in JP-A-5-313284 are preferred.

The amount of the selenium and tellurium sensitizers used in the present invention varies depending on the silver halide grains to be used, the conditions of chemical ripening, and the like, but is generally 1 × 10 ^-8 to 1 × 10 ⁸ per mol of silver halide. ^-2 mol, preferably 1 × 10 ^-7 to 1
About ^10-3 mol is used. The conditions of the chemical sensitization in the present invention are not particularly limited, but the pH is 5 to 8, the pAg is 6 to 11, preferably 7 to 10, and the temperature is 40.
9595 ° C., preferably 45-85 ° C.

As the gold sensitizer used for sensitizing the silver halide emulsion of the present invention to gold, the oxidation number of gold may be +1 or +3, and is usually used as a gold sensitizer. Gold compounds can be used. Representative examples include chloroauric acid, potassium chloroaurate, auric trichloride, potassium auric thiocyanate, potassium iodooleate, tetracyano auric acidide, ammonium aurothiocyanate, pyridyl trichlorogold and the like. Although the amount of the gold sensitizer to be added varies depending on various conditions, the standard is 1 × 10 ⁻⁷ mol to 1 × 10 ⁻³ mol, more preferably 1 × 10 ⁻⁶ mol to 5 mol per mol of silver halide. × 10 ^-4 or less. In the silver halide emulsion used in the present invention, a cadmium salt, a sulfite, a lead salt, during the formation or physical ripening of silver halide grains,
A thallium salt may coexist.

In the present invention, reduction sensitization can be used. As specific compounds of the reduction sensitization method, in addition to ascorbic acid and thiourea dioxide, for example, stannous chloride, aminoiminomethanesulfinic acid, hydrazine derivatives, borane compounds, silane compounds, polyamine compounds and the like can be used. . Also, when the pH of the emulsion is 7 or more or p
Reduction sensitization can be achieved by aging while keeping Ag at 8.3 or less. Further, reduction sensitization can be achieved by introducing a single addition portion of silver ion during grain formation. The silver halide emulsion of the present invention has European special properties of 29.
A thiosulfonic acid compound may be added by the method described in 3,917. The silver halide emulsion in the light-sensitive material used in the present invention may be only one kind or two or more kinds (for example, those having different average grain sizes, those having different halogen compositions, those having different crystal habits, those having chemical sensitization, Those with different conditions) may be used in combination.

The amount of the photosensitive silver halide used in the present invention is preferably 0.01 mol to 0.5 mol, more preferably 0.02 mol to 0.3 mol, and more preferably 0.03 mol to 1 mol of the organic silver salt. It is particularly preferably at least 0.25 mol. Regarding the mixing method and mixing conditions of the separately prepared photosensitive silver halide and organic silver salt, the prepared silver halide particles and organic silver salt were mixed with a high-speed stirrer, ball mill, sand mill, colloid mill, vibration mill, homogenizer, etc. And the like, or a method of preparing an organic silver salt by mixing photosensitive silver halide prepared at any timing during the preparation of the organic silver salt. There is no particular limitation as long as it appears in. The preferable addition time of the silver halide of the present invention to the coating solution for the image forming layer is from 180 minutes to immediately before coating, and preferably from 60 minutes to 10 seconds before coating. There is no particular limitation as long as the effects of the invention are sufficiently exhibited. As a specific mixing method, a method of mixing in a tank in which the average residence time calculated from the addition flow rate and the amount of liquid sent to the coater is a desired time or N.Ha
There is a method using a static mixer or the like described in Chapter 8 of “Liquid Mixing Technology” (published by Nikkan Kogyo Shimbun, 1989) by Koji Takahashi, rnby, MFEdwards, AWNienow, and the like.

The organic silver salt that can be used in the present invention is
Relatively stable to light, but in the presence of an exposed photocatalyst (such as a latent image of photosensitive silver halide) and a reducing agent,
A silver salt that forms a silver image when heated to 80 ° C. or higher. The organic silver salt can be any organic substance including a source capable of reducing silver ions. Silver salts of organic acids, especially silver salts of long chain fatty carboxylic acids (with 10 to 30, preferably 15 to 28 carbon atoms) are preferred. Also preferred are organic or inorganic silver salt complexes in which the ligand has a complex stability constant in the range of 4.0 to 10.0. The silver donor is preferably about 5-70% by weight of the imaging layer.
Can be configured. Preferred organic silver salts include silver salts of organic compounds having a carboxyl group. Examples of these include, but are not limited to, silver salts of aliphatic carboxylic acids and silver salts of aromatic carboxylic acids. Preferred examples of the silver salt of the aliphatic carboxylic acid include silver behenate, silver arachidate, silver stearate, silver oleate, silver laurate, silver caproate, silver myristate, silver palmitate, silver maleate, and silver maleate. Silver salt, silver tartrate, silver linoleate, silver butyrate and silver camphorate, and mixtures thereof.

The organic acid silver which is preferably used in the present invention is
It is prepared by reacting silver nitrate with an alkali metal salt (eg, Na salt, K salt, Li salt, etc.) solution or suspension of the organic acid described above. The alkali metal salt of an organic acid of the present invention is obtained by treating the above organic acid with an alkali. The organic acid silver salt of the present invention can be performed palindrically or continuously in any suitable container. The stirring in the reaction vessel can be performed by any stirring method depending on the required characteristics of the particles. The silver salt of an organic acid can be prepared by gradually or rapidly adding an aqueous solution of silver nitrate to a reaction vessel containing a solution or suspension of an alkali metal salt of an organic acid, or by preparing an organic acid prepared in advance in a reaction vessel containing an aqueous solution of silver nitrate. Preferably, a method of gradually or rapidly adding an alkali metal salt solution or suspension, and a method of simultaneously adding a previously prepared aqueous solution of silver nitrate and a solution or suspension of an organic acid alkali metal salt into a reaction vessel are preferably used. Can be.

The silver nitrate aqueous solution and the organic acid alkali metal salt solution or suspension may be of any concentration for controlling the particle size of the organic silver salt to be adjusted, and may be added at any addition rate. it can. The silver nitrate aqueous solution and the organic acid alkali metal salt solution or suspension can be added by a method of adding at a constant addition rate, an accelerated addition method by an arbitrary time function, or a deceleration addition method. Also, the reaction solution may be added to the liquid surface,
Further, it may be added to the liquid. In the case of a method in which a previously prepared aqueous silver nitrate solution and an organic acid alkali metal salt solution or suspension are simultaneously added to the reaction vessel, either the silver nitrate aqueous solution or the organic acid alkali metal salt solution or suspension is preceded. Although it can be added, it is preferable to add the silver nitrate aqueous solution in advance. The degree of precedence is preferably from 0 to 50% of the total added amount, particularly preferably from 0 to 25%. Further, as described in JP-A-9-127643, a method of adding while controlling the pH or silver potential of the reaction solution during the reaction can be preferably used.

The silver nitrate aqueous solution or organic acid alkali metal salt solution or suspension to be added depends on the required properties of the particles.
pH can be adjusted. Any acid or alkali can be added for pH adjustment. Depending on the required characteristics of the particles, for example, the temperature in the reaction vessel can be arbitrarily set for controlling the particle size of the organic silver salt to be adjusted. Alternatively, the suspension can also be adjusted to any temperature. The organic acid alkali metal salt solution or suspension is preferably heated and kept at 50 ° C. or higher in order to ensure fluidity of the solution.

The organic acid silver used in the present invention is preferably prepared in the presence of a tertiary alcohol. The tertiary alcohol used in the present invention preferably has a total carbon number of 15 or less, particularly preferably 10 or less. Preferred examples of the tertiary alcohol include tert-butanol, but the present invention is not limited thereto.

The tertiary alcohol used in the present invention may be added at any time during the preparation of the silver salt of the organic acid. Is preferred. The amount of the tertiary alcohol of the present invention can be arbitrarily used in a weight ratio of 0.01 to 10 with respect to H ₂ O as a solvent at the time of preparing the silver salt of an organic acid. Is preferred.

Silver salts of compounds containing a mercapto group or a thione group and derivatives thereof can also be used. Preferred examples of these compounds include 3-mercapto-4-
Silver salt of phenyl-1,2,4-triazole, silver salt of 2-mercaptobenzimidazole, silver salt of 2-mercapto-5-aminothiadiazole, silver salt of 2- (ethylglycolamide) benzothiazole, S-alkylthio Silver salts of thioglycolic acid such as silver salts of glycolic acid (where the alkyl group has 12 to 22 carbon atoms); silver salts of dithiocarboxylic acids such as silver salts of dithioacetic acid; silver salts of thioamide; Silver salt of carboxyl-1-methyl-2-phenyl-4-thiopyridine, silver salt of mercaptotriazine, silver salt of 2-mercaptobenzoxazole, silver salt described in U.S. Pat.No.4,123,274, for example, 3-amino-5- Silver salts of 1,2,4-mercaptothiazole derivatives such as silver salts of benzylthio-1,2,4-thiazole, 3- (3-carboxyethyl) -4- described in U.S. Pat.No.3,301,678.
Includes silver salts of thione compounds such as silver salt of methyl-4-thiazoline-2-thione. Furthermore, compounds containing an imino group can also be used. Preferred examples of these compounds include silver salts of benzotriazole and derivatives thereof, for example, silver salts of benzotriazole such as silver methylbenzotriazole, silver salts of halogen-substituted benzotriazole such as silver 5-chlorobenzotriazole, and US Pat. No. 4,220,
No. 709, silver salts of 1,2,4-triazole or 1-H-tetrazole, and silver salts of imidazole and imidazole derivatives. For example, various silver acetylide compounds as described in U.S. Pat. Nos. 4,761,361 and 4,775,613 can also be used.

The shape of the organic silver salt that can be used in the present invention is not particularly limited, but a needle crystal having a short axis and a long axis is preferable. In the present invention, the minor axis is 0.01 μm or more and 0.2 μm or more.
0 μm or less, major axis of 0.10 μm or more and 5.0 μm or less, minor axis of 0.01 μm or more and 0.15 μm or less, and major axis of 0.10 μm or more and 4.0 μm or less are more preferred. The particle size distribution of the organic silver salt is preferably monodispersed. Monodisperse is the standard deviation of the lengths of the minor and major axes divided by the minor and major axes, respectively.
0 fraction is preferably 100% or less, more preferably 80% or less,
More preferably, it is 50% or less. The shape of the organic silver salt can be measured from a transmission electron microscope image of the organic silver salt dispersion. As another method of measuring monodispersity, there is a method of determining the standard deviation of the volume-weighted average diameter of the organic silver salt, the percentage of the value divided by the volume-weighted average diameter (coefficient of variation) is preferably 100% or less, more Preferably 80% or less,
More preferably, it is 50% or less. As a measuring method, for example, a particle size (volume weighted average diameter) obtained by irradiating a laser beam to an organic silver salt dispersed in a liquid and obtaining an autocorrelation function with respect to a time change of fluctuation of the scattered light.
Can be obtained from

The organic silver salt that can be used in the present invention includes:
Preferably, desalting can be performed. The method for desalting is not particularly limited, and a known method can be used. However, a known filtration method such as centrifugal filtration, suction filtration, ultrafiltration, or floc-forming water washing by a coagulation method can be preferably used.

In the present invention, in order to obtain an organic silver salt solid dispersion having a high S / N, a small particle size, and no aggregation, an organic silver salt which is an image forming medium and a photosensitive silver salt are substantially contained. It is preferable to use a dispersion method in which a water dispersion liquid which is not included in the liquid is converted into a high-speed flow and then the pressure is reduced.

After passing through these steps, the mixture is mixed with a photosensitive silver salt aqueous solution to prepare a photosensitive image forming medium coating solution. When a photothermographic material is prepared using such a coating solution, a haze is low, and a low-fogging, high-sensitivity photothermographic material can be obtained. On the other hand, when the photosensitive silver salt is coexistent when the light is converted into a high-pressure, high-speed flow and dispersed, the fog increases and the sensitivity is remarkably lowered. When an organic solvent is used instead of water as a dispersion medium, haze increases, fog increases, and sensitivity tends to decrease. On the other hand, when a conversion method for converting a part of the organic silver salt in the dispersion to the photosensitive silver salt is used instead of the method of mixing the aqueous solution of the photosensitive silver salt, the sensitivity is reduced. In the above, the high-pressure, the aqueous dispersion is dispersed and converted to high speed, is substantially free of photosensitive silver salt, the water content is 0.1 mol% based on the non-photosensitive organic silver salt The following is the case where the photosensitive silver salt is not positively added.

In the present invention, the solid dispersion apparatus and the technique used for carrying out the dispersion method as described above are described in, for example, "Dispersion Rheology and Dispersion Technology" (Toshio Kajiuchi and Hiroki Usui, 1991, Shinzansha Publishing Co., Ltd., p357
-P403), "The 24th Progress of Chemical Engineering", edited by The Society of Chemical Engineers, Tokai Branch, 1990, Maki Shoten, p184-p185),
Although detailed in the dispersing method of the present invention, the aqueous dispersion containing at least an organic silver salt is pressurized by a high-pressure pump or the like and sent into a pipe, and then passed through a narrow slit provided in the pipe, Thereafter, the dispersion is finely dispersed by causing an abrupt pressure drop in the dispersion.

The high-pressure homogenizer to which the present invention relates generally comprises (a) a "shear force" generated when the dispersoid passes through a narrow gap at a high pressure and a high speed; It is considered that the particles are dispersed into fine particles by a dispersing force such as “cavitation force” generated when the particles are released. As an example of this type of dispersing apparatus, a Gaulin homogenizer is mentioned in the past.In this apparatus, the liquid to be dispersed sent at a high pressure is converted into a high-speed flow through a narrow gap on a cylindrical surface, and the force is applied to the surrounding wall by the force. The particles collide and are emulsified and dispersed by the impact force. Working pressure is generally 10
0~600kg / cm ^2, the flow rate is in the range of a few M～30m / sec, be devised that the high flow rate portion was devised such increasing the number collisions in the saw-toothed in order to increase the dispersion efficiency I have. On the other hand, in recent years, apparatuses capable of dispersing at higher pressure and higher flow rate have been developed, and typical examples thereof include a microfluidizer (Microfluidex International Corporation) and a nanomizer (specialized machine). Industrial Co., Ltd.).

Examples of the dispersion apparatus suitable for the present invention include a microfluidizer M-110S-EH (with a G10Z interaction chamber), M-110Y (with a H10Z interaction chamber), and M-110S-EH manufactured by Microfluidics International Corporation. -140K (with G10Z interaction chamber), HC-5000 (with L30Z or H230Z interaction chamber), HC-8000 (with E230Z or L3
0Z interaction chamber).

Using these devices, an aqueous dispersion containing at least an organic silver salt is pressurized by a high-pressure pump or the like and fed into a pipe, and then passed through a narrow slit provided in the pipe to obtain a desired pressure. Is applied, and thereafter, the pressure in the pipe is rapidly returned to the atmospheric pressure, or the like, and a sudden pressure drop is caused in the dispersion to obtain an organic silver salt dispersion optimal for the present invention. .

Prior to the dispersion operation, it is preferable to pre-disperse the raw material liquid. As means for preliminary dispersion, known dispersion means (for example, high-speed mixer, homogenizer, high-speed impact mill, Banbury mixer, homomixer, kneader, ball mill, vibration ball mill, planetary ball mill, attritor, sand mill, bead mill, colloid mill,
Jet mill, roller mill, tron mill, high-speed stone mill) can be used. Instead of mechanically dispersing, fine particles may be formed by coarsely dispersing in a solvent by controlling the pH and then changing the pH in the presence of a dispersing agent. At this time, an organic solvent may be used as a solvent used for the coarse dispersion, and the organic solvent is usually removed after the completion of the fine particle formation.

In the organic silver salt dispersion of the present invention, the flow rate,
It is possible to disperse to a desired particle size by adjusting the pressure difference at the time of pressure drop and the number of treatments, but from the viewpoint of photographic characteristics and particle size, the flow rate is 200 m / sec to 600 m / sec. The pressure is preferably in the range of 900 to 3000 kg / cm ² and the flow rate is 3
00m / sec-600m / sec, differential pressure at the time of pressure drop is 1500-3000kg /
More preferably, it is in the range of cm ² . The number of times of dispersion processing can be selected as needed, but usually 1 to 10 times is selected, but from the viewpoint of productivity, about 1 to 3 times is selected. It is not preferable to raise the temperature of such an aqueous dispersion under high pressure from the viewpoint of dispersibility and photographic characteristics.At a temperature higher than 90 ° C., the particle size tends to increase, and the fog tends to increase. is there. Therefore, in the present invention, the step before the conversion to the high pressure and high flow rate, the step after the pressure is reduced, or both of these steps includes a cooling step, and the temperature of such water dispersion is reduced by 5% by the cooling step. It is preferably maintained in the range of ~ 90 ° C, more preferably in the range of 5 ~ 80 ° C, especially 5 ~ 65 ° C
Is preferably maintained within the range. In particular, 1500-30
It is effective to provide the above cooling step at the time of high pressure dispersion in the range of 00 kg / cm ² . As the cooler, a double tube, a double tube using a static mixer, a multi-tube heat exchanger, a coiled tube heat exchanger, or the like can be appropriately selected according to the required heat exchange amount. Further, in order to increase the efficiency of heat exchange, it is sufficient to select a suitable one such as a pipe thickness, a wall thickness and a material in consideration of a working pressure. The refrigerant used for the cooler should be 20 ° C well water, 5-10 ° C cold water treated by a refrigerator, and if necessary, -30 ° C ethylene glycol / water refrigerant, etc. You can also.

In the dispersion operation of the present invention, it is preferable to disperse the organic silver salt in the presence of an aqueous solvent-soluble dispersant (dispersing aid). Examples of the dispersing agent include polyacrylic acid, a copolymer of acrylic acid, a maleic acid copolymer, a maleic acid monoester copolymer, a synthetic anionic polymer such as an acrylomethylpropanesulfonic acid copolymer, and carboxymethyl. Starch, semi-synthetic anionic polymers such as carboxymethyl cellulose, alginic acid, anionic polymers such as pectic acid, the compounds described in JP-A-7-350753, or known anionic, nonionic, cationic surfactants and other polyvinyl Known polymers such as alcohol, polyvinylpyrrolidone, carboxymethylcellulose, hydroxypropylcellulose, and hydroxypropylmethylcellulose, and naturally occurring polymer compounds such as gelatin can be appropriately selected and used. Le compounds, particularly preferred water-soluble cellulose derivatives.

It is a general method to mix a dispersion aid with an organic silver salt powder or an organic silver salt in a wet cake state before dispersion, and to send the mixture as a slurry to a dispersing machine. Heat treatment or treatment with a solvent may be performed in the combined state to obtain an organic silver salt powder or a wet cake. The pH may be controlled by a suitable pH adjuster before, during or after dispersion.

In addition to mechanical dispersion, the dispersion may be roughly dispersed in a solvent by controlling the pH, and then the pH may be changed in the presence of a dispersing agent to form fine particles. At this time, an organic solvent may be used as a solvent used for the coarse dispersion, and the organic solvent is usually removed after the completion of the fine particle formation.

The prepared dispersion is stored with stirring for the purpose of suppressing sedimentation of fine particles during storage, or stored in a highly viscous state (for example, in a jelly state using gelatin) by means of a hydrophilic colloid. You can also.
Further, a preservative can be added for the purpose of preventing the propagation of various bacteria during storage.

The particle size (volume weight average diameter) of the organic silver salt solid fine particle dispersion of the present invention is determined, for example, by irradiating a solid fine particle dispersion dispersed in a liquid with a laser beam and changing the fluctuation of the scattered light with time. It can be obtained from the particle size (volume weight average diameter) obtained by obtaining the autocorrelation function. Average particle size 0.05μm or more 10.0μm
The following solid fine particle dispersions are preferred. More preferably, the average particle size is from 0.1 μm to 5.0 μm, and still more preferably, the average particle size is from 0.1 μm to 2.0 μm.

The particle size distribution of the organic silver salt is preferably monodispersed. Specifically, the percentage (coefficient of variation) of the value obtained by dividing the standard deviation of the volume load average diameter by the volume load average diameter is 80% or less, more preferably 50% or less, and still more preferably 30% or less.

The shape of the organic silver salt can be measured from a transmission electron microscope image of the organic silver salt dispersion.

The organic silver salt solid fine particle dispersion used in the present invention comprises at least an organic silver salt and water. The ratio between the organic silver salt and water is not particularly limited, but the ratio of the organic silver salt to the whole is preferably 5 to 50 wt%, particularly preferably 10 to 30 wt%. Although it is preferable to use the aforementioned dispersing aid, it is preferable to use a minimum amount in a range suitable for minimizing the particle size #,
It is preferably in the range of 1 to 30% by weight, particularly 3 to 15% by weight, based on the organic silver salt. In the present invention, it is possible to produce a photosensitive material by mixing an aqueous dispersion of an organic silver salt and an aqueous dispersion of a photosensitive silver salt,
The mixing ratio of the organic silver salt and the photosensitive silver salt can be selected according to the purpose. A range of 15 mol% is preferred. Mixing two or more aqueous dispersions of organic silver salts with two or more aqueous dispersions of photosensitive silver salts during mixing is a method preferably used for adjusting photographic characteristics.

[0057] While the organic silver salt according to the invention can be used in a desired amount, preferably 0.1-5 g / m ² as silver amount, more preferably from 1 to 3 g / m ^2.

The photothermographic material of the present invention preferably contains a reducing agent for an organic silver salt. The reducing agent for the organic silver salt may be any substance that reduces silver ions to metallic silver, preferably an organic substance. Conventional photographic developers such as phenidone, hydroquinone and catechol are useful, but hindered phenol reducing agents are preferred. The reducing agent is 5 to 50% based on 1 mol of silver on the surface having the image forming layer.
It is preferably contained in a molar amount, more preferably 10 to 40 mol%. The layer to which the reducing agent is added may be any layer on the side having the image forming layer. When it is added to a layer other than the image forming layer, it is preferable to use a relatively large amount of 10 to 50 mol% with respect to 1 mol of silver. Further, the reducing agent may be a so-called precursor which is derivatized so as to have a function effectively only during development.

In a photothermographic material using an organic silver salt, a wide range of reducing agents are disclosed in JP-A-46-6074 and JP-A-47-1238.
47-33621, 49-46427, 49-115540, 50-14
No. 334, No. 50-36110, No. 50-147711, No. 51-32632,
No. 51-1023721, No. 51-32324, No. 51-51933, No. 52-8
4727, 55-108654, 56-146133, 57-82828
No. 57-82829, JP-A-6-3793, U.S. Pat.
No. 86, No. 3,679,426, No. 3,751,252, No. 3,751,255
Nos. 3,761,270, 3,782,949, 3,839,048,
3,928,686, 5,464,738, German patent 2321328,
It is disclosed in European Patent No. 692732 and the like. For example, phenylamide oxime, 2-thienylamide oxime and
Amide oximes such as p-phenoxyphenylamide oxime; azines such as 4-hydroxy-3,5-dimethoxybenzaldehyde azine; combinations of 2,2′-bis (hydroxymethyl) propionyl-β-phenylhydrazine with ascorbic acid Combinations of such aliphatic carboxylic acid aryl hydrazides with ascorbic acid; polyhydroxybenzene, hydroxylamine, reductone and / or
Or a combination of hydrazines (eg, hydroquinone and
Bis (ethoxyethyl) hydroxylamine, a combination of piperidinohexose reductone or formyl-4-methylphenylhydrazine); hydroxamic acids such as phenylhydroxamic acid, p-hydroxyphenylhydroxamic acid and β-alinine hydroxamic acid; Combinations of azine and sulfonamidophenol (e.g., phenothiazine and 2,6-dichloro-4-benzenesulfonamidophenol, etc.); α such as ethyl-α-cyano-2-methylphenylacetate, ethyl-α-cyanophenylacetate -Cyanophenylacetic acid derivative; 2,2'-dihydroxy-1,
1'-binaphthyl, 6,6'-dibromo-2,2'-dihydroxy-1,
Bis-β-naphthol as exemplified by 1′-binaphthyl and bis (2-hydroxy-1-naphthyl) methane; bis-β-
Combinations of naphthol and 1,3-dihydroxybenzene derivatives (eg, such as 2,4-dihydroxybenzophenone or 2 ′, 4′-dihydroxyacetophenone); 5-pyrazolone, such as 3-methyl-1-phenyl-5-pyrazolone; Reductones as exemplified by dimethylaminohexose reductone, anhydrodihydroaminohexose reductone and anhydrodihydropiperidone hexose reductone; 2,6-dichloro-4-benzenesulfonamidophenol and p-benzenesulfone Sulfonamidophenol reducing agents such as amidophenol; 2-phenylindane
Chromanes such as 2,2-dimethyl-7-t-butyl-6-hydroxychroman; 1 such as 2,6-dimethoxy-3,5-dicarboethoxy-1,4-dihydropyridine 2,4-dihydropyridine; bisphenol (eg, bis (2-hydroxy-3-t-butyl-5-methylphenyl) methane, 2,2-bis
(4-hydroxy-3-methylphenyl) propane, 4,4-ethylidene-bis (2-t-butyl-6-methylphenol), 1,1,-
Bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane and 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane etc.); ascorbic acid derivatives
(Eg, 1-ascorbyl palmitate, ascorbyl stearate, etc.); and aldehydes and ketones, such as benzyl and biacetyl; 3-pyrazolidones and certain indan-1,3-diones; chromanols (such as tocopherol). Particularly preferred reducing agents are bisphenol and chromanol.

The reducing agent of the present invention may be added by any method such as a solution, a powder, and a solid fine particle dispersion. The dispersion of the solid fine particles is carried out by a known means for making fine (for example, a ball mill, a vibration ball mill, a sand mill, a colloid mill, a jet mill, a roller mill, etc.). When dispersing the solid fine particles, a dispersing aid may be used.

When an additive known as a "toning agent" for improving an image is contained, the optical density may be increased. The toning agent may also be advantageous in forming a black silver image. The toning agent is preferably contained in an amount of 0.1 to 50 mol% per mol of silver on the surface having the image forming layer,
More preferably, the content is 0.5 to 20 mol%. Further, the toning agent may be a so-called precursor which is derivatized so as to have a function effectively only during development.

In a photothermographic material utilizing an organic silver salt, a wide range of color tones are disclosed in JP-A-46-6077 and JP-A-47-10282.
Nos. 49-5019, 49-5020, 49-91215, 49-9
No. 1215, No. 50-2524, No. 50-32927, No. 50-67132,
No. 50-67641, No. 50-114217, No. 51-3223, No. 51-279
No. 23, No. 52-14788, No. 52-99813, No. 53-1020, No. 5
3-76020, 54-156524, 54-156525, 61-1836
No. 42, JP-A-4-56848, JP-B-49-10727, 54-2033
No. 3, U.S. Pat.Nos. 3,080,254, 3,446,648, 3,782,9
No. 41, No. 4,123,282, No. 4,510,236, British Patent 138079
No. 5, Belgian Patent No. 841910 and the like. Examples of toning agents are phthalimide and N-hydroxyphthalimide; succinimide, pyrazolin-5-one and quinazolinone, 3-phenyl-2-pyrazolin-5-one, 1-phenylurazole, quinazoline and 2,4-thiazolidinedione Cyclic imides such as; naphthalimides (eg, N
-Hydroxy-1,8-naphthalimide); cobalt complexes (eg, cobalt hexamine trifluoroacetate); 3-
Mercapto-1,2,4-triazole, 2,4-dimercaptopyrimidine, 3-mercapto-4,5-diphenyl-1,2,4-triazole and 2,5-dimercapto-1,3,4-thiadiazole N- (aminomethyl) aryldicarboximides, such as (N, N-dimethylaminomethyl) phthalimide and N, N- (dimethylaminomethyl) -naphthalene-2,3-dicarboximide ); And blocked pyrazoles, isothiuronium derivatives and certain photobleaching agents (eg, N, N'-hexamethylenebis (1-carbamoyl-3,5-dimethylpyrazole), 1,8-
(3,6-diazaoctane) bis (isothiuronium trifluoroacetate) and 2-tribromomethylsulfonyl)-(benzothiazole)); and 3-ethyl-5 [(3-
Ethyl-2-benzothiazolinylidene) -1-methylethylidene] -2-thio-2,4-oxazolidinedione; phthalazinone, a phthalazinone derivative or a metal salt, or 4- (1-
Naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-
Derivatives such as dimethoxyphthalazinone and 2,3-dihydro-1,4-phthalazinedione; phthalazinone and phthalic acid derivatives (for example, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic anhydride) Phthalazine, phthalazine derivative or metal salt,
Or derivatives such as 4- (1-naphthyl) phthalazine, 6-chlorophthalazine, 5,7-dimethoxyphthalazine and 2,3-dihydrophthalazine; phthalazine and phthalic acid derivatives (eg, phthalic acid, 4-methylphthalic acid) Quinazolinedione, benzoxazine or naphthoxazine derivatives; not only as a color tone regulator but also as a source of halide ions for silver halide formation in situ. A working rhodium complex, such as hexachlororhodium (III)
Ammonium phosphate, rhodium bromide, rhodium nitrate and potassium hexachlororhodate (III) and the like; inorganic peroxides and persulfates such as ammonium disulfide and hydrogen peroxide; 1,3-benzoxazine-2,4 -Dione, 8-methyl-1,3-benzoxazine-2,4-dione and
Benzoxazine-2,4-dione such as 6-nitro-1,3-benzoxazine-2,4-dione; pyrimidine and asymmetric triazines (eg, 2,4-dihydroxypyrimidine, 2-hydroxy-4-amino) Pyrazidine, etc.), azauracil, and tetraazapentalene derivatives (eg, 3,6-dimercapto-1,4-diphenyl-1H, 4H-2,3a, 5,6a-tetraazapentalene, and 1,4-diphenyl (o-chlorophenyl) -3,6-dimercapto-1H, 4H-2,3a, 5,6a-tetraazapentalene).

The color tone agent of the present invention may be added by any method such as a solution, a powder, and a solid fine particle dispersion. The dispersion of the solid fine particles is carried out by a known fine means (for example, ball mill, vibrating ball mill, sand mill, colloid mill, jet mill, roller mill, etc.). When dispersing the solid fine particles, a dispersing aid may be used.

The effect of the present invention is that the organic silver salt-containing layer is
When formed by applying and drying using a coating solution containing 30 wt% or more of water, the binder of the organic silver salt-containing layer (hereinafter referred to as “the polymer of the present invention”) can be added to an aqueous solvent (aqueous solvent). It is soluble or dispersible, and is particularly improved when the polymer latex has an equilibrium water content at 25 ° C. and 60% RH of 2% by weight or less. The most preferred form has an ionic conductivity of 2.5 mS /
cm or less, and such a preparation method includes, for example, a method of purifying using a separation functional membrane after polymer synthesis.

The aqueous solvent in which the polymer of the present invention is soluble or dispersible is water or a mixture of water and 70% by weight or less of a water-miscible organic solvent. Examples of the water-miscible organic solvent include, for example, alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol;
Examples thereof include cellosolves such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve, ethyl acetate, and dimethylformamide. Note that the term “aqueous solvent” is used herein even in a system in which the polymer is not thermodynamically dissolved but exists in a so-called dispersed state.

The “equilibrium water content at 25 ° C. and 60% RH” referred to in the present invention refers to the weight W1 of the polymer which is in a humidity control equilibrium in an atmosphere of 25 ° C. and 60% RH, and the weight of the polymer which is in an absolutely dry state at 25 ° C. weight
It can be expressed as follows using W0.

Equilibrium water content at 25 ° C. and 60% RH = [(W1-W0)
/ W0) × 100 (wt%)

The definition and measurement method of the water content are described in, for example, Polymer Engineering Course 14, Polymer Material Testing Method (edited by the Society of Polymer Science,
You can refer to Citizen Library). The equilibrium water content of the polymer of the present invention at 25 ° C. and 60% RH is preferably 2% by weight or less, more preferably 0.01% by weight or more and 1.5% by weight or less, further preferably 0.02% by weight or more and 1% by weight or less. The polymer of the present invention is not particularly limited as long as it is soluble or dispersible in the above-mentioned aqueous solvent and has an equilibrium water content at 25 ° C. and 60% RH of 2 wt% or less. Among these polymers, polymers that can be dispersed in an aqueous solvent are particularly preferred.

Examples of the dispersion state include a latex in which fine particles of a solid polymer are dispersed, and a dispersion state in which polymer molecules are dispersed in a molecular state or micelles.

In a preferred embodiment of the present invention, acrylic resin, polyester resin, rubber resin (for example, SB
R resin), a hydrophobic polymer such as a polyurethane resin, a vinyl chloride resin, a vinyl acetate resin, a vinylidene chloride resin, and a polyolefin resin. The polymer may be a linear polymer, a branched polymer, or a crosslinked polymer. The polymer may be a so-called homopolymer in which a single monomer is polymerized, or a copolymer in which two or more monomers are polymerized. In the case of a copolymer, even a random copolymer,
It may be a block copolymer. The polymer has a number average molecular weight of 5000 to 100000, preferably 10,000 to 200,000. If the molecular weight is too small, the mechanical strength of the emulsion layer is insufficient, and if it is too large, the film-forming properties are poor, which is not preferable.

The polymer of the present invention is a polymer in which these polymers are dispersed in an aqueous dispersion medium. Here, the aqueous system refers to a dispersion medium in which 30% by weight or more of the composition is water. The dispersion state may be any state such as emulsified and dispersed, micelle dispersed, and further dispersed in a molecular state of a polymer having a hydrophilic site in a molecule, and of these, latex is particularly preferred. .

Specific examples of preferred polymers include the following. In the following, the raw material monomers are used, the numerical value in parentheses is wt%, and the molecular weight is the number average molecular weight. P-1; -MMA (70) -EA (27) -MAA (3)-latex (molecular weight 370
00) Latex of P-2; -MMA (70) -2EHA (20) -St (5) -AA (5)-(molecular weight 40000) P-3; -St (50) -Bu (47) -MAA ( 3) -Latex (molecular weight 4500
0) Latex of P-4; -St (68) -Bu (29) -AA (3)-(molecular weight 6000
0) Latex of P-5; -St (70) -Bu (27) -IA (3)-(molecular weight 12000
0) Latex of P-6; -St (75) -Bu (24) -AA (1)-(molecular weight 10800
0) P-7; -St (60) -Bu (35) -DVB (3) -MAA (2)-latex (molecular weight 150,000) P-8; -St (70) -Bu (25) -DVB ( 2) -AA (3)-latex (molecular weight 280000) P-9; -VC (50) -MMA (20) -EA (20) -AN (5) -AA (5)-latex (molecular weight 80000) P-10; -VDC (85) -MMA (5) -EA (5) -MAA (5)-latex (molecular weight 67000) P-11; -Et (90) -MAA (10)-latex (molecular weight 12000)

The abbreviations of the above structures represent the following monomers.
MMA; methyl methacrylate, EA; ethyl acrylate, MAA; methacrylic acid, 2EHA; 2-ethylhexyl acrylate, St; styrene, Bu; butadiene, AA; acrylic acid, DVB; divinylbenzene, VC; vinyl chloride, AN; acrylonitrile, VDC; Vinylidene chloride, Et; ethylene, IA; itaconic acid.

The polymers described above are commercially available, and the following polymers can be used. Examples of the acrylic resin include Sebian A-4635,46583,4601 (all manufactured by Daicel Chemical Industries, Ltd.), Nipol Lx811, 814,821,820,
Examples of polyester resins such as 857 (manufactured by Nippon Zeon Co., Ltd.) include FINETEX ES650, 611, 675, 850 (manufactured by Dainippon Ink and Chemicals, Inc.), WD-size, WMS (manufactured by Eastman Chemical Co., Ltd.) Examples of polyurethane resins include HYDRAN AP10, 20, 30, and 40 (all manufactured by Dainippon Ink and Chemicals, Inc.). Examples of rubber resins include LACSTAR 73.
Examples of vinyl chloride resins such as 10K, 3307B, 4700H, 7132C (manufactured by Dainippon Ink and Chemicals, Inc.), Nipol Lx416, 410, 438C, and 2507 (manufactured by Nippon Zeon Co., Ltd.) include G3
Examples of vinylidene chloride resins include L502 and L513 (manufactured by Asahi Chemical Industry Co., Ltd.). Examples of olefin resins include Chemipearl S120 and SA100 (manufactured by Mitsui. Petrochemical Co., Ltd.). These polymers may be used alone as a polymer latex, or two or more may be blended if necessary.

The polymer latex used in the present invention is particularly preferably a styrene-butadiene copolymer latex. The weight ratio of the styrene monomer unit to the butadiene monomer unit in the styrene-butadiene copolymer is preferably from 40:60 to 95: 5. The ratio of the styrene monomer unit and the butadiene monomer unit in the copolymer is preferably 60 to 99% by weight. The preferred molecular weight range is the same as described above.
Examples of the styrene-butadiene copolymer latex that is preferably used in the present invention include the above-mentioned P-3 to P-8, commercially available products such as LACSTAR-3307B, 7132C, and Nipol Lx416.

The organic silver salt-containing layer of the light-sensitive material of the present invention may optionally contain a hydrophilic polymer such as gelatin, polyvinyl alcohol, methylcellulose and hydroxypropylcellulose. The amount of these hydrophilic polymers added is 30 wt% or less of the total binder in the organic silver salt-containing layer,
More preferably, it is 20 wt% or less. Although the organic silver salt-containing layer of the present invention is formed using a polymer latex, the amount of the binder in the organic silver salt-containing layer is such that the weight ratio of the total binder / organic silver salt is 1 / 1-10. / 1, even 1/5
A range of 44/1 is preferred. Such an organic silver salt-containing layer is usually a photosensitive layer (emulsion layer) containing a photosensitive silver halide which is a photosensitive silver salt. In such a case, the total binder / silver halide Is preferably in the range of 400-5, more preferably 200-10. The total amount of binder in the image forming layer of the present invention is 0.2 to 30 g / m ^2, more preferably in the range of 1 to 15 g / m ^2. A crosslinking agent for crosslinking, a surfactant for improving coating properties, and the like may be added to the image forming layer of the invention.

In the present invention, the solvent of the coating solution for the organic silver salt-containing layer of the light-sensitive material (the solvent and the dispersion medium are collectively referred to as a solvent for simplicity) is an aqueous solvent containing 30% by weight or more of water. As a component other than water, any water-miscible organic solvent such as methyl alcohol, ethyl alcohol, isopropyl alcohol, methyl cellosolve, ethyl cellosolve, dimethylformamide, and ethyl acetate may be used. The water content of the solvent in the coating solution is preferably at least 50 wt%, more preferably at least 70 wt%. An example of a preferred solvent composition is water /
Methyl alcohol = 90/10, water / methyl alcohol = 70/3
0, water / methyl alcohol / dimethylformamide = 80/1
5/5, water / methyl alcohol / ethyl cellosolve = 85/10 /
5, water / methyl alcohol / isopropyl alcohol = 8
5/10/5 and others.

As the sensitizing dye in the present invention, any dye can be used as long as it can spectrally sensitize silver halide grains in a desired wavelength region when adsorbed on silver halide grains. As the sensitizing dye, a cyanine dye, a merocyanine dye, a complex cyanine dye, a complex merocyanine dye, a holo-holerocyanine dye, a styryl dye, a hemicyanine dye, an oxonol dye, a hemioxonol dye, and the like can be used. Useful sensitizing dyes for use in the present invention include, for example, RESEARCH DISCLOSURE Item 17
Item 643IV-A (p.23, December 1978), Item 1831X (August 1979)
p.437) or in the literature cited. In particular, a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of the light source of various laser imagers, scanners, imagesetters and plate making cameras can be advantageously selected.

As an example of spectral sensitization to red light, He-Ne
For a so-called red light source such as a laser, a red semiconductor laser or an LED, a compound of I-1 to I-38 described in JP-A-54-18726, and a compound of I-1 described in JP-A-6-75322. I-3
5 and the compounds I-1 to I- described in JP-A-7-287338.
34 compounds, dyes 1 to 20 described in JP-B-55-39818,
The compounds I-1 to I-37 described in JP-A-62-284343 and the compounds I-1 to I-34 described in JP-A-7-287338 are advantageously selected.

For semiconductor laser light sources in the wavelength region of 750 to 1400 nm, various known dyes including cyanine, merocyanine, styryl, hemicyanine, oxonol, hemioxonol and xanthene dyes are spectrally advantageously sensitized. Can be done. Useful cyanine dyes are, for example, cyanine dyes having basic nuclei such as thiazoline nuclei, oxazoline nuclei, pyrroline nuclei, pyridine nuclei, oxazole nuclei, thiazole nuclei, selenazole nuclei and imidazole nuclei. Preferred useful merocyanine dyes include, in addition to the above basic nuclei, acidic nuclei such as thiohydantoin nucleus, rhodanine nucleus, oxazolidinedione nucleus, thiazolinedione nucleus, barbituric acid nucleus, thiazolinone nucleus, malononitrile nucleus and pyrazolone nucleus. Including. Among the above cyanine and merocyanine dyes, those having an imino group or a carboxyl group are particularly effective. For example, U.S. Patent 3,761,279,
3,719,495 and 3,877,943, British Patent 1,466,201
No. 1,469,117, No. 1,422,057, Tokuhei 3-10391
No. 6-52387, JP-A-5-341432, 6-94781,
It may be appropriately selected from known dyes as described in JP-A-6-301141.

Particularly preferred as the structure of the dye used in the present invention is a cyanine dye having a thioether bond-containing substituent (for example, JP-A Nos. 62-58239 and 3-1386).
No.38, No.3-138642, No.4-255840, No.5-72659, No.5
-72661, 6-222491, 2-230506, 6-258757
No., 6-317868, 6-324425, Tokuyohei 7-500926,
Dyes described in U.S. Pat.No. 5,541,054), dyes having a carboxylic acid group (for example, JP-A-3-163440, 6-30114
No. 1, dyes described in U.S. Pat.No.
No. 52-80829, No. 54-61517, No. 59-214846, No. 60-67
No. 50, 63-159841, JP-A-6-35109, 6-59381
No., 77-146537, 77-146537, Tokuyohei 55-50111,
Dyes described in British Patent 1,467,638 and US Patent 5,281,515). Further, as a dye forming a J-band, U.S. Pat. Can be used.

These sensitizing dyes may be used alone.
Two or more kinds may be used in combination. Combinations of sensitizing dyes are often used, especially for supersensitization. Along with the sensitizing dye, the emulsion may contain a dye which does not itself have a spectral sensitizing effect or a substance which does not substantially absorb visible light and exhibits supersensitization. Useful sensitizing dyes, combinations of dyes exhibiting supersensitization and substances exhibiting supersensitization are Re.
search Disclosure Volume 176, 17643 (Issued December 1978) Page 23
IV, J, or JP-B-49-25500, JP-B-43-4933, JP-A-59-19032, and JP-A-59-192242.

The sensitizing dyes may be added to the silver halide emulsion by dispersing them directly in the emulsion or by adding water, methanol, ethanol, propanol, acetone, methylcellosolve, 2,2, 3,3-tetrafluoropropanol, 2,2,2-trifluoroethanol, 3-methoxy
It may be added to the emulsion by dissolving it in a solvent such as 1-propanol, 3-methoxy-1-butanol, 1-methoxy-2-propanol, N, N-dimethylformamide, alone or in a mixed solvent.

As disclosed in US Pat. No. 3,469,987, a dye is dissolved in a volatile organic solvent, the solution is dispersed in water or a hydrophilic colloid, and this dispersion is dispersed in an emulsion. To Japanese Patent Publication No. 44-23389,
As disclosed in 44-27555, 57-22091, etc.,
A method in which a dye is dissolved in an acid and the solution is added to the emulsion, or a method in which an acid or a base is added to the emulsion as an aqueous solution in the coexistence thereof, as disclosed in U.S. Pat.Nos. 3,822,135 and 4,006,025, etc. A method of adding an aqueous solution or a colloidal dispersion in the presence of a surfactant to an emulsion, as disclosed in JP-A-53-102733 and JP-A-58-105141. Is directly dispersed, and the dispersion is added to the emulsion, as disclosed in JP-A-51-74624, the dye is dissolved using a compound that causes a red shift, and the solution is added to the emulsion. Can be used. Also, ultrasonic waves can be used for the solution.

The sensitizing dye used in the present invention may be added to the silver halide emulsion of the present invention at any time during the preparation of the emulsion which has been found to be useful. For example, U.S. Patents 2,735,766 and 3,628,960,
4,183,756, 4,225,666, JP-A-58-184142,
As disclosed in the specification of JP-A-60-196749 and the like, the timing before the step of forming silver halide grains and / or before desalting, during and / or after desalting and before the start of chemical ripening. As disclosed in the specification such as JP-A-58-113920, any time immediately before the chemical ripening or during the process, after the chemical ripening, and before the application of the emulsion before coating, It may be added during the process.
Further, as disclosed in the specification of U.S. Pat. No. 4,225,666, JP-A-58-7629, etc., the same compound may be used alone or in combination with a compound having a different structure, for example, during the particle forming step. The compound may be divided and added during the ripening step or after the completion of the chemical ripening, or may be added separately before or during the chemical ripening or after the completion of the chemical ripening. May be added.

The amount of the sensitizing dye used in the present invention may be a desired amount in accordance with the performance such as sensitivity and fog.
The amount is preferably from 10 ^-6 to 1 mol, more preferably from 10 ^-4 to 10 ^-1 mol, per mol of silver halide in the photosensitive layer.

The silver halide emulsion according to the present invention or /
And the organic silver salts can be further protected against the formation of additional fog by antifoggants, stabilizers and stabilizer precursors, and can be stabilized against reduced sensitivity during stock storage. Suitable antifoggants, stabilizers and stabilizer precursors that can be used alone or in combination are the thiazonium salts described in U.S. Pat.Nos. 2,131,038 and 2,694,716; U.S. Pat.Nos. 2,886,437 and 2,444,605. Azaindene, U.S. Pat.
8,663 mercury salt, U.S. Pat.No. 3,287,135 urazole, U.S. Pat.No. 3,235,652 sulfocatechol, British Patent 623,448 Oxime,
Nitrone, nitroindazole, U.S. Patent No. 2,839,405
No. 3,220,839, thiuronium salts, and U.S. Pat.Nos. 2,566,263 and 2,597,915, palladium, platinum and gold salts, U.S. Pat.Nos. 4,108,665 and 4,442,202 No. 4,128,557
Nos. 4,137,079 and 4,138,365 and 4,
No. 4,59,350 and U.S. Pat.
And the phosphorus compounds described in No. 1,985.

The antifoggant preferably used in the present invention is an organic halide, for example, as described in JP-A-50-119624.
No. 50-120328, No. 51-121332, No. 54-58022, No.
56-70543, 56-99335, 59-90842, 61-12964
No. 2, 62-129845, JP-A-6-208191, 7-5621,
Nos. 7-2781, 8-15809, U.S. Pat.
Compounds such as those disclosed in US Pat.

The antifoggant of the present invention may be added by any method such as a solution, a powder, and a dispersion of solid fine particles. The dispersion of the solid fine particles is carried out by a known means for making fine (for example, a ball mill, a vibration ball mill, a sand mill, a colloid mill, a jet mill, a roller mill, etc.). When dispersing the solid fine particles, a dispersing aid may be used.

Although not required to practice the present invention,
It may be advantageous to add a mercury (II) salt as an antifoggant to the emulsion layer. Preferred mercury (II) salts for this purpose are
Mercury acetate and mercury bromide. The amount of mercury used in the present invention is preferably 1 × 10 ⁻⁹ mol to 1 × 10 ⁻³ mol, more preferably 1 × 10 ⁻³ mol, per mol of coated silver.
It is in the range of 10 ⁻⁹ mol to 1 × 10 ⁻⁴ mol.

The photothermographic material of the present invention may contain benzoic acids for the purpose of increasing the sensitivity and preventing fog. The benzoic acids of the present invention may be any benzoic acid derivative, but examples of preferred structures include those described in U.S. Pat.
No. 9, No. 4, 152, 160, Japanese Patent Application No. 8-151242, No. 8-151241
And the compounds described in JP-A-8-98051 and the like. The benzoic acids of the present invention may be added to any part of the light-sensitive material. However, the added layer is preferably added to a layer having a light-sensitive layer, more preferably to an organic silver salt-containing layer. . The benzoic acid of the present invention may be added at any time during the preparation of the coating solution, and when it is added to the organic silver salt-containing layer, it may be added at any time from the preparation of the organic silver salt to the preparation of the coating solution. It is preferable after salt preparation and immediately before application. The benzoic acid of the present invention may be added by any method such as powder, solution, and fine particle dispersion. Further, it may be added as a solution mixed with other additives such as a sensitizing dye, a reducing agent and a color tone agent. The benzoic acid of the present invention may be added in any amount, but preferably from 1 × 10 ⁻⁶ mol to 2 mol per mol of silver, more preferably from 1 × 10 ⁻⁶ mol to 2 mol.
^- more preferably ³ mol to 0.5 mol.

In the present invention, a mercapto compound, a disulfide compound, and a thione compound are contained to control development by suppressing or accelerating development, to improve spectral sensitization efficiency, to improve storage stability before and after development, and the like. be able to. When using a mercapto compound in the present invention, any structure may be used, but Ar-SM, Ar-SSA
Those represented by r are preferred. Wherein M is a hydrogen atom or an alkali metal atom, and Ar is an aromatic or fused aromatic ring having one or more nitrogen, sulfur, oxygen, selenium or tellurium atoms. Preferably, the heteroaromatic ring is benzimidazole, naphthimidazole, benzothiazole, naphthothiazole, benzoxazole, naphthoxazole, benzoselenazole, benzotellurazole, imidazole, oxazole, pyrazole, triazole, thiadiazole, tetrazole, triazine, pyrimidine, pyridazine , Pyrazine, pyridine, purine, quinoline or quinazolinone. The heteroaromatic ring can be, for example, halogen (eg, Br and Cl), hydroxy, amino, carboxy, alkyl (eg, 1
From a substituent group consisting of at least one carbon atom, preferably having 1 to 4 carbon atoms, and alkoxy (for example, having at least one carbon atom, preferably having 1 to 4 carbon atoms). It may have one to be selected. As mercapto-substituted heteroaromatic compounds, 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole, 2-mercapto-5-
Methylbenzimidazole, 6-ethoxy-2-mercaptobenzothiazole, 2,2'-dithiobis- (benzothiazole, 3-mercapto-1,2,4-triazole, 4,5-diphenyl-2-imidazolethiol, 2- Mercaptoimidazole, 1-ethyl-2-mercaptobenzimidazole, 2-mercaptoquinoline, 8-mercaptopurine, 2-mercapto
-4 (3H) -quinazolinone, 7-trifluoromethyl-4-quinolinethiol, 2,3,5,6-tetrachloro-4-pyridinethiol, 4-amino-6-hydroxy-2-mercaptopyrimidine monohydrate , 2-amino-5-mercapto-1,3,4-thiadiazole, 3-amino-5-mercapto-1,2,4-triazole,
4-Hydrocyr-2-mercaptopyrimidine, 2-mercaptopyrimidine, 4,6-diamino-2-mercaptopyrimidine, 2
-Mercapto-4-methylpyrimidine hydrochloride, 3-mercapto-5-phenyl-1,2,4-triazole, 2-mercapto-4-phenyloxazole, and the like, but the invention is not limited thereto.

The addition amount of these mercapto compounds is preferably in the range of 0.001 to 1.0 mol per mol of silver in the emulsion layer, more preferably 0.01 to 0.1 mol per mol of silver.
3 moles.

In the photosensitive layer of the present invention, a polyhydric alcohol (for example, US Pat.
Glycerin and diols of the type described in U.S. Pat. No. 960,404), fatty acids or esters described in U.S. Pat. Nos. 2,588,765 and 3,121,060, and silicone resins described in British Patent No. 955,061.

In the present invention, a super-high contrast agent can be used for forming a super-high contrast image. For example, U.S. Patent No. 5,464,73
No. 8, No. 5,496,695, No. 6,512,411, No. 5,536,622,
Japanese Patent Application Nos. Hei 7-228627, Hei 8-215822, Hei 8-130842
Nos. 8-148113, 8-156378, 8-148111, 8-
The hydrazine derivative described in 148116, the compound having a quaternary nitrogen atom described in Japanese Patent Application No. 8-83566, and the acrylonitrile compound described in US Pat. No. 5,545,515 can be used. Specific examples of the compound include compounds 1 to 10 and 5,5,4 of the aforementioned U.S. Patent No. 5,464,738.
H-1 to H-28 of 96,695, I-1 to I-8 of Japanese Patent Application No. 8-215822
6, H-1 to H-62 of 8-130842, 1-1 to 1-2 of 8-148113
1, 1 to 50 of 8-148111, 1 to 40 of 8-148116, 8 to 8
No. 3,566, P-1 to P-26, and T-1 to T-18, U.S. Pat.
No. 5,515, CN-1 to CN-13 and the like.

Further, the present invention provides a method for forming a super-high contrast image.
A high contrast accelerator can be used in combination with the above-mentioned super-high contrast agent. For example, amine compounds described in U.S. Pat.No. 5,545,505, specifically AM-1 to AM-5, hydroxamic acids described in 5,545,507, specifically HA-1 to HA-11, and the like.
Acrylonitrile described in 5,545,507, specifically C
Hydrazine compounds described in N-1 to CN-13 and 5,558,983, specifically CA-1 to CA-6, onium salts described in Japanese Patent Application No. 8-132836, specifically A-1 to A-42, B-1 to
B-27, C-1 to C-14 and the like can be used. The synthesis method, addition method, addition amount, and the like of these super-high contrast agents and high-contrast accelerators can be performed as described in each of the cited patents.

The image forming material of the present invention may have a surface protective layer for the purpose of preventing adhesion of the image forming layer. Although any polymer may be used as the binder for the surface protective layer of the present invention, the binder preferably contains a polymer having a carboxylic acid residue in an amount of from 100 mg / m ^{2 to} 5 g / m ² . Examples of the polymer having a carboxyl residue include natural polymers (gelatin, alginic acid, etc.), modified natural polymers (carboxymethylcellulose, phthalated gelatin, etc.), and synthetic polymers (polymethacrylate, polyacrylate, polyalkylmethacrylate / acrylate). Copolymer, polystyrene / polymethacrylate copolymer, etc.). The content of carboxy residues in the polymer is 1 × 10 ^-2 mol or more per 100 g of the polymer.
It is preferably at most 4 mol. Further, the carboxylic acid residue may form a salt with an alkali metal ion, an alkaline earth metal ion, an organic cation, or the like.

As the surface protective layer of the present invention, any anti-adhesion material may be used. Examples of anti-adhesion materials include waxes, silica particles, styrene-containing elastomeric block copolymers (eg, styrene-butadiene-
Styrene, styrene-isoprene-styrene), cellulose acetate, cellulose acetate butyrate, cellulose propionate, and mixtures thereof. Further, a crosslinking agent for crosslinking and a surfactant for improving coating properties may be added to the surface protective layer.

In the image forming layer or the protective layer of the image forming layer in the present invention, US Pat. Nos. 3,253,921 and 2,27
It can be used in photographic elements containing light absorbing materials and filter dyes as described in 4,782, 2,527,583 and 2,956,879. Also, dyes can be mordanted, for example, as described in US Pat. No. 3,282,699. The amount of the filter dye used is preferably such that the absorbance at the exposure wavelength is 0.1 to 3.0, and 0.1.
2-1.5 is particularly preferred. The image forming layer or the image forming layer of the emulsion layer in the present invention may contain a matting agent such as starch, titanium dioxide, zinc oxide, silica, and US Pat.
Polymer beads including beads of the type described in 2,101 and 2,701,245 can be included.
The matte degree of the emulsion surface may be any value as long as no star dust failure occurs, but the Beck smoothness is preferably from 50 seconds to 10,000 seconds, and particularly preferably from 80 seconds to 10,000 seconds.

The temperature for preparing the image forming layer coating solution of the present invention is 30.
℃ 65 ℃ or less, more preferred temperature is 35 ℃ 60
It is below ° C. Further, the temperature of the image forming layer coating solution immediately after the addition of the polymer latex may be maintained at 30 ° C. or more and 65 ° C. or less. Preferably, the reducing agent and the organic silver salt are mixed before the latex is added. The fluid containing an organic silver salt or the coating solution for the thermal image forming layer in the present invention is preferably a so-called thixotropic fluid. The thixotropic property refers to a property in which the viscosity decreases as the shear rate increases. Although any apparatus may be used for the viscosity measurement of the present invention, an RFS fluid spectrometer manufactured by Rheometrics Far East Co., Ltd. is preferably used.
Measured at 5 ° C. Here, the viscosity of the fluid containing the organic silver salt or the coating solution for the thermal image forming layer in the present invention at a shear rate of 0.1 S ^-1 is 400 mPa.s. It is preferably from 100 mPa · s to 100,000 mPa · s, and more preferably from 500 mPa · s to 20,000 mPa · s. Further, at a shear rate of 1000 S ^-1 is preferably 1 mPas or more and 200 mPas or less, more preferably 5 mPas
s or more and 80 mPa · s or less.

Various systems expressing thixotropy are known, and are described in “Lecture / Rheology” edited by Polymer Publishing Association, Muroi,
It is described in Morino co-authored "Polymer Latex" (published by the Society of Polymer Publishing). In order for a fluid to exhibit thixotropic properties, it is necessary to contain a large amount of solid fine particles.
In order to enhance the thixotropic property, it is effective to include a thickened linear polymer, to increase the aspect ratio of the contained solid fine particles in an anisotropic shape, to increase the alkali thickening, and to use a surfactant.

The photothermographic material of the present invention comprises one or more layers on a support. One layer construction must include optional additional materials such as organic silver salts, silver halides, developers and binders, and toning agents, coating aids and other auxiliaries. The two-layer configuration is the first
It must contain an organic silver salt and silver halide in the emulsion layer (usually the layer adjacent to the base) and some other components in the second layer or both layers. However, a two-layer construction comprising a single emulsion layer containing all components and a protective topcoat is also contemplated. The construction of a multicolor photothermographic material may include a combination of these two layers for each color, and may include all components in a single layer as described in U.S. Pat.No. 4,708,928. Is also good. In the case of a multi-dye, multi-color photothermographic material, each emulsion layer is generally, as described in U.S. Pat.No. 4,460,681,
The use of a functional or non-functional barrier layer between each photosensitive layer keeps it distinct from each other.

Various dyes and pigments can be used in the photosensitive layer of the present invention from the viewpoint of improving color tone and preventing irradiation. Dyes and pigments used in the photosensitive layer of the present invention may be any, for example, there are pigments and dyes described in the color index, specifically pyrazoloazole dye, anthraquinone dye, azo dye, azomethine dye,
Organic dyes such as oxonol dyes, carbocyanine dyes, styryl dyes, triphenylmethane dyes, indoaniline dyes and indophenol dyes, azo pigments, polycyclic pigments (phthalocyanine pigments, anthraquinone pigments, etc.), dyeing lake pigments, Organic pigments including azine pigments, inorganic pigments and the like can be mentioned. Preferred dyes used in the present invention include anthraquinone dyes (for example, compounds 1 to 9 described in JP-A-5-341441, JP-A-5-165147).
Nos. 3-6-18 and 3-23-38), azomethine dyes (compounds 17-47 described in JP-A-5-341441), indoaniline dyes (e.g. compounds described in JP-A-5-289227) 11 to 19, compound 47 described in JP-A-5-341441,
Compounds 2-10 to 11 described in JP-A-5-165147) and azo dyes (compounds 10 to 16 described in JP-A-5-341441) are preferable pigments. Preferred pigments are anthraquinone-based indanthrone pigments (CI Pigment Blue 60). Phthalocyanine pigments (copper phthalocyanine such as CI Pigment Blue 15; CI
Pigment Blue 16 and the like, and non-metallic phthalocyanines such as Pigment Blue 16), dyed lake pigment based triarylcarbonyl pigments, indigo, and inorganic pigments (ultramarine, cobalt blue, etc.). As a method for adding these dyes and pigments, any method such as a solution, an emulsion, a solid fine particle dispersion, and a state in which the dye or pigment is mordanted with a polymer mordant may be used. The amount of these compounds used is determined depending on the desired absorption amount, but it is generally preferable to use them in an amount of 1 μg or more and 1 g or less per m ² .
Further, a dioxane-based pigment, a quinacridone-based pigment, a diketopyrrolopyrrole-based pigment, or the like may be used in combination for adjusting redness.

In the present invention, the antihalation layer can be provided on the side farther from the light source than the photosensitive layer. The antihalation layer preferably has a maximum absorption in a desired wavelength range of 0.3 or more and 2 or less, more preferably an absorption of an exposure wavelength of 0.5 or more and 2 or less, and an absorption in a visible region after processing of 0.001 or more. It is preferably less than 0.5, and more preferably a layer having an optical density of 0.001 or more and less than 0.3.

When an antihalation dye is used in the present invention, the dye has a desired absorption in the wavelength range, has a sufficiently low absorption in the visible region after the treatment, and has a desirable absorbance spectrum shape of the antihalation layer. Any compound can be used as long as it is possible. For example, the following are disclosed, but the present invention is not limited thereto.
As a single dye, JP-A-59-56458, JP-A-2-216140
No. 7-13295, No. 7-11432, U.S. Pat.No.5,380,635, JP-A-2-688539, page 13, lower left column, line 1
On page 9, lower left column, line 9, there are compounds described in JP-A-3-24539 from page 14, lower left column to page 16, lower right column. 53-132334, 56-501
480, 57-16060, 57-68831, 57-101835,
No. 59-182436, JP-A-7-36145, JP-A-7-199409, JP-B-48-33692, JP-B50-16648, JP-B-2-41734, U.S. Patent 4,088,497, JP-A-4,283,487, JP-A-4,548,896 No.
There is 5,187,049.

The photothermographic material of the present invention is a so-called one-sided light-sensitive material having at least one photosensitive layer containing a silver halide emulsion on one side of a support and a back layer on the other side. Preferably, there is.

In the present invention, a matting agent may be added to the single-sided photosensitive material in order to improve transportability. The matting agent is generally fine particles of an organic or inorganic compound insoluble in water. Any matting agent can be used, for example, U.S. Patent Nos. 1,939,213, 2,701,245, and 2,322,037.
No. 3,262,782, No. 3,539,344, No. 3,767,448, etc.
2,192,241, 3,257,206, 3,370,951, 3,52
Inorganic matting agents well-known in the art, such as inorganic matting agents described in the respective specifications such as 3,022 and 3,769,020, can be used. For example, specifically, examples of organic compounds that can be used as a matting agent include, as examples of water-dispersible vinyl polymers, polymethyl acrylate, polymethyl methacrylate, polyacrylonitrile, acrylonitrile-α-methylstyrene copolymer, and polystyrene. , Styrene-divinylbenzene copolymer, polyvinyl acetate, polyethylene carbonate, polytetrafluoroethylene, etc., examples of cellulose derivatives such as methylcellulose,
Examples of starch derivatives such as cellulose acetate, cellulose acetate propionate, carboxy starch, carboxynitrophenyl starch, urea-formaldehyde-
Gelatin hardened with a known hardener such as a starch reactant and hardened gelatin obtained by coacervate hardening to form fine capsule hollow particles can be preferably used. Examples of the inorganic compound include silicon dioxide, titanium dioxide, magnesium dioxide, aluminum oxide, barium sulfate, calcium carbonate, silver chloride desensitized by a known method, silver bromide, glass, and diatomaceous earth. . The above matting agents can be used by mixing different types of substances as necessary. The size and shape of the matting agent are not particularly limited, and those having an arbitrary particle size can be used. In practicing the present invention, it is preferable to use one having a particle size of 0.1 μm to 30 μm. Further, the particle size distribution of the matting agent may be narrow or wide. On the other hand, since the matting agent greatly affects the haze and surface gloss of the light-sensitive material, the particle size, shape, and particle size distribution can be changed as necessary during the preparation of the matting agent or by mixing a plurality of matting agents. preferable.

In the present invention, the matting degree of the back layer is preferably such that the Bekk smoothness is 250 seconds or less and 10 seconds or more, and more preferably 180 seconds or less and 50 seconds or more. In the present invention, the matting agent is preferably contained in the layer functioning as the outermost surface layer or the outermost surface layer of the light-sensitive material, or a layer close to the outer surface, and is contained in a layer acting as a so-called protective layer. Is preferred.

In the present invention, suitable binders for the back layer are transparent or translucent, generally colorless, and natural polymer synthetic resins, polymers and copolymers, and other film-forming media such as: gelatin, gum arabic, poly (vinyl) Alcohol), hydroxyethylcellulose, cellulose acetate, cellulose acetate butyrate, poly (vinylpyrrolidone), casein, starch, poly (acrylic acid), poly (methylmethacrylic acid), poly (vinyl chloride), poly (methacrylic acid), copoly (Styrene-maleic anhydride), copoly (styrene-
Acrylonitrile), copoly (styrene-butadiene), poly (vinyl acetal) s (eg, poly (vinyl formal) and poly (vinyl butyral)), poly (esters), poly (urethane) s, phenoxy resins, poly (chlorinated) Vinylidene), poly (epoxide) s,
Poly (carbonate) s, poly (vinyl acetate),
There are cellulose esters and poly (amides). The binder may be coated from water or an organic solvent or emulsion.

In the present invention, the back layer preferably has a maximum absorption of 0.3 or more and 2 or less in a desired wavelength range.
More preferably absorption is 0.5 or more and 2 or less, and the absorption in the visible region after the treatment is preferably 0.001 or more and less than 0.5, and more preferably a layer having an optical density of 0.001 or more and less than 0.3. . Examples of the antihalation dye used in the back layer are the same as those of the antihalation layer described above.

US Pat. Nos. 4,460,681 and 4,374,9
Backside resistive heating layer as shown in No. 21
stive heating layer) can also be used in a photosensitive heat developed photographic image system.

A hardener may be used for each layer such as the photosensitive layer, the protective layer and the back layer of the present invention. Examples of hardeners include T.
"THE THEORY OF THE PHOTOGRAPHIC PROCESS" by H. James
FOURTH EDITION "(published by Macmillan Publishing Co., Inc.,
Each method is described from page 77 to page 87.
Polyvalent metal ions described on page, U.S. Pat.No. 4,281,060,
Polyisocyanates such as JP-A-6-208193, epoxy compounds such as U.S. Pat.No. 4,791,042, JP-A-62-8904
Vinyl sulfone compounds such as No. 8 are preferably used. The hardener is added as a solution, and the time of addition of the solution to the protective layer coating solution is from 180 minutes to immediately before application, preferably from 60 minutes to 10 seconds before application, but regarding the mixing method and mixing conditions. Is not particularly limited as long as the effects of the present invention are sufficiently exhibited. As a specific mixing method, a method of mixing in a tank in which the average residence time calculated from the addition flow rate and the amount of liquid sent to the coater is a desired time or N.
There is a method using a static mixer or the like described in Chapter 8 of Harnby, MFE Edwards, AWNienow, "Liquid Mixing Technology" translated by Koji Takahashi (Nikkan Kogyo Shimbun, 1989).

In the present invention, a surfactant may be used for the purpose of improving coating properties and charging. As the surfactant, any surfactant such as nonionic, anionic, cationic, and fluorine can be used as appropriate. Specifically,
No. 62-170950, Fluoropolymer surfactants described in U.S. Pat.No. 5,380,644, JP-A-60-244945, JP-A-63-18
8135 No. fluorinated surfactants described in U.S. Pat.
No. 5,965, and the like, and polysiloxy acid-based surfactants described in JP-A-6-301140 and the like, and polyalkylene oxide and anionic surfactants.

Examples of the solvent used in the present invention include New Solvent Pocket Book (Ohm Co., 1994), but the present invention is not limited thereto. The solvent used in the present invention has a boiling point of 40 ° C or more and 180 ° C or more.
C. or lower is preferred. Examples of the solvent of the present invention include hexane, cyclohexane, toluene, methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, ethyl acetate, 1,1,1-trichloroethane, tetrahydrofuran, triethylamine, thiophene, trifluoroethanol, perfluoropentane, xylene , N-
Butanol, phenol, methyl isobutyl ketone, cyclohexanone, butyl acetate, diethyl carbonate, chlorobenzene, dibutyl ether, anisole, ethylene glycol diethyl ether, N, N-dimethylformamide,
Examples include morpholine, propane sultone, perfluorotributylamine, water and the like.

The heat-developable photographic emulsion of the present invention can be coated on various supports. Typical supports include polyester films, primed polyester films, poly (ethylene terephthalate) films, polyethylene naphthalate films, cellulose nitrate films, cellulose ester films, poly (vinyl acetal) films, polycarbonate films and related or resinous Including materials, as well as glass, paper, metal and the like. Flexible substrates, especially partially acetylated or baryta and / or α-olefin polymers, especially polyethylene, polypropylene, ethylene-
Paper supports coated with polymers of α-olefins having 2 to 10 carbon atoms, such as butene copolymers, are typically used. The support may be transparent or opaque, but is preferably transparent.

The light-sensitive material of the present invention comprises an antistatic or conductive layer such as a soluble salt (for example, chloride or nitrate), a vapor-deposited metal layer, US Pat. Nos. 2,861,056 and
It may have a layer containing an ionic polymer as described in US Pat. No. 3,206,312 or an insoluble inorganic salt as described in US Pat. No. 3,428,451.

As a method for obtaining a color image using the heat-developable photosensitive material of the present invention, there is a method described in JP-A-7-13295, page 10, left column, line 43 to 11 left column, line 40. Further, as a color dye image stabilizer, British Patent No. 1,326,889, U.S. Patent No. 3,432,300, No. 3,698,909, No. 3,574,62
No. 7, No. 3,573,050, No. 3,764,337 and No. 4,0
No. 42,394.

The photothermographic material of the present invention may be applied by any method. Specifically, extrusion coating, slide coating, curtain coating, dip coating, knife coating,
Various coating operations are used, including flow coating or extrusion coating using a hopper of the type described in U.S. Pat. No. 2,681,294, and are described by Stephen F. Kistl.
er, "LIQUID FILM COATING" by Peter M. Schweizer (C
Extrusion coating or slide coating described on pages 399 to 536, published by HAPMAN & HALL (1997) is preferably used, and particularly preferably slide coating is used. An example of the shape of the slide coater used for slide coating is shown in Figure 11 on page 427 of the same book.
in b.1. Also, if desired, the method described on page 399 to 536 of the same book, U.S. Pat.No. 2,761,791 and British Patent 837,0
Two or more layers can be coated simultaneously by the method described in No. 95.

In the heat-developable photographic material of the present invention, additional layers, such as a dye-receiving layer for receiving a moving dye image, an opaque layer if reflective printing is desired, a protective topcoat layer and photothermographic techniques A known primer layer or the like can be included. The light-sensitive material of the present invention is preferably capable of forming an image with only one light-sensitive material, and it is preferable that a functional layer required for image formation such as an image receiving layer does not become another light-sensitive material.

In the heat-developable photographic material of the present invention, additional layers, such as a dye-receiving layer for receiving a moving dye image, an opaque layer if reflective printing is desired, a protective topcoat layer and photothermographic techniques It may include a known primer layer and the like. The light-sensitive material of the present invention is preferably capable of forming an image with only one light-sensitive material, and it is preferable that a functional layer required for image formation such as an image receiving layer does not become another light-sensitive material.

[0121]

The present invention will be specifically described below with reference to examples. Example 1 << Preparation of PET support >> Terephthalic acid and ethylene glycol
PET with intrinsic viscosity IV = 0.66 (measured in phenol / tetrachloroethane = 6/4 (weight ratio) at 25 ° C.) according to a conventional method
I got This was pelletized, dried at 130 ° C. for 4 hours, melted at 300 ° C., extruded from a T-die, quenched, and formed into an unstretched film having a thickness of 175 μm after heat setting. .

This was longitudinally stretched 3.3 times using rolls having different peripheral speeds, and then transversely stretched 4.5 times using a tenter. The temperatures at this time were 110 ° C. and 130 ° C., respectively.
After that, it was heat-set at 240 ° C. for 20 seconds and relaxed 4% in the lateral direction at the same temperature. Then, after slitting the chuck portion of the tenter, knurling was performed on both ends and wound at 4 kg / cm ² to obtain a roll having a thickness of 175 μm.

<< Surface Corona Treatment >> Using a solid state corona treatment machine 6KVA model manufactured by Pillar Co., both surfaces of the support were treated at room temperature at 20 m / min. From the current and voltage readings at this time, it was found that the support was treated at 0.375 kV · A · min / m ² . The processing frequency at this time is
9.6kHz, gap clearance between electrode and dielectric roll
1.6 mm.

<< Preparation of Undercoating Support >> (Preparation of Undercoating Coating Solution A) Polystyrene fine particles (average particle size: 0.2 μm) ) 1g, surfactant 1
(1 wt%) 20 ml was added, and distilled water was added thereto to make 1000 ml, thereby obtaining an undercoating coating solution A.

(Preparation of Undercoat Coating Solution B) Styrene-butadiene copolymer aqueous dispersion (styrene / butadiene / itaconic acid = 47/50/3 (weight ratio), concentration: 30 wt%) in 680 ml of distilled water
0 ml and 0.1 g of polystyrene fine particles (average particle size 2.5 μm) were added, and distilled water was further added to make 1000 ml.
And

(Preparation of Undercoating Coating Solution C) Inert Gelatin 1
0 g was dissolved in 500 ml of distilled water, and 40 g of an aqueous dispersion (40 wt%) of tin oxide-antimony oxide composite fine particles described in JP-A-61-20033 was added thereto, and distilled water was added thereto. Ten
Undercoating solution C was made up to 00 ml.

(Preparation of Undercoating Support) After the above-described corona discharge treatment, the undercoating coating solution A was applied using a bar coater so that the wet coating amount was 5 ml / m ² , and dried at 180 ° C. for 5 minutes. The dry film thickness was about 0.3 μm. Next, after applying a corona discharge treatment to the back surface (back surface), the undercoat coating solution B was applied using a bar coater so that the wet coating amount was 5 ml / m ² and the dry film thickness was about 0.3 μm. After drying for 5 minutes, further apply undercoating coating solution C with a bar coater so that the wet coating amount is 3 ml / m ² and the dry film thickness is about 0.03 μm, and then dry at 180 ° C for 5 minutes to support the undercoating Created body.

<< Preparation of Organic Acid Silver Dispersion >> 43.8 g of behenic acid (product name: Edenor C22-85R) manufactured by Henkel, 730 ml of distilled water,
While stirring 60 ml of tert-butanol at 79 ° C., 117 ml of a 1N-NaOH aqueous solution was added over 55 minutes and reacted for 240 minutes. Then
112.5 ml of an aqueous solution of 19.2 g of silver nitrate was added over 45 seconds, left as it was for 20 minutes, and cooled to 30 ° C. Thereafter, the solid content was separated by suction filtration, and the solid content of the filtrate had a conductivity of 30 μS / cm.
And washed with water. The solid content thus obtained is handled as a wet cake without drying, and
To a wet cake equivalent to 100 g, 7.4 g of polyvinyl alcohol (trade name: PVA-205) and water were added, and the total amount was adjusted to 385 g, followed by preliminary dispersion with a homomixer.

Next, the pre-dispersed stock solution is dispersed in a disperser (trade name: Microfluidizer M-110S-EH, manufactured by Microfluidics International Corporation, using G10Z interaction chamber).
The pressure was adjusted to 1750 kg / cm ² and the mixture was treated three times to obtain a silver behenate dispersion B. The silver behenate particles contained in the silver behenate dispersion thus obtained were needle-like particles having an average minor axis of 0.04 μm, an average major axis of 0.8 μm, and a variation coefficient of 30%. For particle size measurement, use MasterSizerX manufactured by Malvern Instruments Ltd.
I went in. In the cooling operation, a coiled heat exchanger was mounted before and after the interaction chamber, and the temperature of the refrigerant was adjusted to a desired dispersion temperature.

<< Preparation of 25% Dispersion of Reducing Agent >> 1,1-bis (2-
(Hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane 80 g and 20% of modified Poval MP203 manufactured by Kuraray Co., Ltd.
176 g of water was added to 64 g of the aqueous solution and mixed well to form a slurry. 800 g of zirconia beads having an average diameter of 0.5 mm were prepared, placed in a vessel together with the slurry, and dispersed for 5 hours with a dispersing machine (1 / 4G sand grinder mill: manufactured by IMEX Co., Ltd.) to obtain a reducing agent dispersion. The reducing agent particles contained in the reducing agent dispersion thus obtained had an average particle size of 0.72 μm.

<< Preparation of 20% Dispersion of Mercapto Compound >> 3
224 g of water was added to 64 g of -mercapto-4-phenyl-5-heptyl-1,2,4-triazole and 32 g of a 20% aqueous solution of modified Poval MP203 manufactured by Kuraray Co., Ltd. and mixed well to form a slurry.
800 g of zirconia beads having an average diameter of 0.5 mm were prepared, placed in a vessel together with the slurry, and dispersed with a dispersing machine (1 / 4G sand grinder mill: manufactured by IMEX Co., Ltd.) for 10 hours to obtain a mercapto dispersion. The mercapto compound particles contained in the thus obtained mercapto compound dispersion have an average particle size.
It was 0.67 μm.

<< Preparation of 30% Dispersion of Organic Polyhalide >> 48 g of tribromomethylphenylsulfone and 3-tribromomethylsulfonyl-4-phenyl-5-tridecyl-1,2,4
-48 g of triazole and modified Poval MP203 manufactured by Kuraray Co., Ltd.
224 g of water was added to 48 g of a 20% aqueous solution of the above, and mixed well to form a slurry. Prepare 800 g of zirconia beads with an average diameter of 0.5 mm, put them in a vessel together with the slurry, and use a disperser (1/4
G sand grinder mill: manufactured by Imex Co., Ltd.) for 5 hours to obtain an organic polyhalogen compound dispersion.
The polyhalogen compound particles contained in the polyhalogen compound dispersion thus obtained had an average particle size of 0.74 μm.

<< Preparation of methanol solution of phthalazine compound >> 26 g of 6-isopropylphthalazine was dissolved in 100 ml of methanol and used.

<< Preparation of 20% Dispersion of Pigment >> CI Pigment
64 g of Blue 60 and 6.4 g of Demol N manufactured by Kao Corporation in 250 g of water
Was added and mixed well to obtain a slurry. Average diameter 0.5mm
Of zirconia beads was placed in a vessel together with the slurry, and dispersed in a dispersing machine (1 / 4G sand grinder mill: manufactured by Imex Co., Ltd.) for 25 hours to obtain a pigment dispersion. The pigment particles contained in the pigment dispersion thus obtained had an average particle size of 0.21 μm.

<< Preparation of Silver Halide Grain 1 >> Distilled water 1421
6.7 cc of a 1 wt% potassium bromide solution was added to the cc, and further, 8.2 cc of 1 N nitric acid and 21.8 g of phthalated gelatin were added thereto while stirring in a titanium-coated stainless steel reaction vessel at 35 ° C.
The solution a1 diluted with 159 cc by adding distilled water to 37.04 g of silver nitrate and 32.6 g of potassium bromide in distilled water to a volume of 200 cc
Was prepared, and the entire amount of the solution a1 was added at a constant flow rate over 1 minute while maintaining the pAg at 8.1 by the control double jet method. (The solution b1 was added by the controlled double jet method.) Then, 30 cc of a 3.5% hydrogen peroxide aqueous solution was added, and 3 wt% of benzimidazole was further added.
336 cc of the aqueous solution was added. Then, the solution a1 was again diluted with distilled water to 317.5 cc, and the solution b1 was dissolved with tripotassium hexachloride iridate to a final concentration of 1 × 10 ^-8 mol per mol of silver. 400cc twice the amount of solution b1
Using the solution b2 diluted with distilled water until, again by the controlled double jet method, while maintaining pAg at 8.1,
The solution a2 was added at a constant flow rate over 10 minutes. (solution
b2 added by controlled double jet method)
Add 50 cc of a 0.5% methanol solution of 2-mercapto-5-methylbenzimidazole, further raise the pAg to 7.5 with silver nitrate, adjust the pH to 3.8 with 1N sulfuric acid, stop stirring,
A precipitation / desalting / washing step was performed, 3.5 g of deionized gelatin was added, and 1N sodium hydroxide was added to adjust to pH 6.0 and pAg 8.2 to prepare a silver halide dispersion.

The grains in the completed silver halide emulsion are pure silver bromide grains having an average sphere equivalent diameter of 0.031 μm and a coefficient of variation in sphere equivalent diameter of 11%. The particle size and the like were determined from the average of 1000 particles using an electron microscope. The {100} face ratio of the particles was determined to be 85% using the Kubelka-Munk method.

The emulsion was heated to 50 ° C. while stirring, and N, N ′
5 cc of a 0.5 wt% methanol solution of -dihydroxy-N ″, N ″ -diethylmelamine and 5 cc of a 3.5 wt% methanol solution of phenoxyethanol were added, and after 1 minute, sodium benzenethiosulfonate was added 3 × to 1 mol of silver. 10 ^-5 mol was added. After a further 2 minutes, a solid dispersion of the spectral sensitizing dye 1 (aqueous gelatin solution) was added in an amount of 5 × 10 ⁻³ mol per mol of silver.
After 5 minutes, the tellurium compound was added in an amount of 5 × 10 ⁻⁵ mol per mol of silver, followed by aging for 50 minutes. Immediately before aging, 2-mercapto-5-
Methylbenzimidazole was added in an amount of 1 × 10 ⁻³ mol per mol of silver, the temperature was lowered, and the chemical sensitization was completed to prepare silver halide grains 1.

<< Preparation of Silver Halide Grains 2-8 >> Silver halide grains were prepared in the same manner as for silver halide grains 1 except that the amount of iridium tripotassium hexachloride was changed as shown in Table 1. Particles 2-8 were prepared.

<< Preparation of Emulsion Layer Coating Solution >> (Emulsion Layer Coating Solution No. 1) 103 g of the organic acid silver dispersion obtained above,
20 wt% of polyvinyl alcohol PVA-205 (Kuraray Co., Ltd.)
5 g of a 25% aqueous solution was mixed and kept at 40 ° C., 23.2 g of the 25% reducing agent dispersion, 1.2 g of a 20% aqueous dispersion of the pigment CI Pigment Blue 60, 10.7 g of an organic polyhalide 30% dispersion, 3.1 g of a 20% dispersion of a mercapto compound was added. Then, after adding 106 g of 40 wt% of UF-purified SBR latex kept at 40 ° C. and sufficiently stirring, 6 ml of a methanol solution of a phthalazine compound was added to obtain a liquid containing an organic acid silver salt. In addition, silver halide grains 1 to 8 were each mixed with a solution containing an organic acid silver by a static mixer immediately before coating 10 g of each of the silver halide grains to prepare an emulsion layer coating solution, and the silver coating amount was directly applied to a coating die at 1.4 g / m ^2. Was sent.

The viscosity of the emulsion layer coating solution was measured with a B-type viscometer (Tokyo Keiki Co., Ltd.) and found to be 85 mPa at 40 ° C. (using a No. 1 rotor).
.S]. 25 using an RFS fluid spectrometer manufactured by Rheometrics Far East Co., Ltd.
The viscosity of the coating solution at ℃ is 0.1, 1, 10, 100, 100
At 0 [1 / sec], 1500, 220, 70, 40, 20 (mP
a · s].

Incidentally, the SBR latex having the following composition was used. (SBR latex: -St (68) -Bu (29) -AA (3)-latex) Equilibrium water content at 25 ° C and 60% RH 0.6wt%, average particle size 0.1μ
m, concentration 45%, ionic conductivity 4.2mS / cm (Ion conductivity was measured using a conductivity meter CM-30S manufactured by Toa Denpa Kogyo Co., Ltd., and the latex stock solution (40%) was measured at 25 ° C), pH 8 .2

<< Preparation of Emulsion Surface Intermediate Layer Coating Solution >> (Intermediate Layer Coating Solution) 772 g of a 10 wt% aqueous solution of polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.), methyl methacrylate / styrene / 2-ethylhexyl acrylate / hydroxyethyl methacrylate / Acrylic acid copolymer (copolymerization weight ratio 59/9/26/5/1) Latex 27.5% liquid 226g with a 5 wt% aqueous solution of Aerosol OT (American Cyanamid Co.)
ml, benzyl alcohol 4g, 2,2,4-trimethyl-1,3-pentanediol mono-isobutyrate 1g and an intermediate layer coating solution was added benzoisothiazolinone 10 mg, a coating die to provide 5 ml / m ² The solution was sent to The viscosity of the coating liquid is B
It was 21 mPa · s at 40 ° C. (using a No. 1 rotor) with a mold viscometer.

<< Preparation of Emulsion Surface Protective Layer First Layer Coating Solution >> (Protective Layer First Layer Coating Solution No. 1) Inert gelatin (80 g) was dissolved in water, phthalic acid (10% methanol solution: 138 ml, 1N sulfuric acid) 28 ml, 5 ml of a 5 wt% aqueous solution of Aerosol OT (manufactured by American Cyanamid Co., Ltd.), 5 g of phenoxyethanol, and water to make a total amount of 1000 g were prepared as a coating solution.
The solution was fed to the coating die so as to be 0 ml / m ² . The viscosity of the coating solution is 17 with a B-type viscometer at 40 ° C (using a No. 1 rotor).
[MPa · s].

<< Preparation of Coating Solution for Emulsion Surface Protective Layer Second Layer >> (Protective Layer Second Layer Coating Solution) Inert gelatin (100 g) was dissolved in water, and N-perfluorooctylsulfonyl-N-propylalanine potassium salt 5% 20 ml of solution, aerosol OT
16 ml of a 5 wt% solution (manufactured by American Cyanamid Co., Ltd.) and polymethyl methacrylate fine particles (average particle size 4.0 μm) 25
g, 44 ml of 1N sulfuric acid, 10 mg of benzoisothiazolinone, water was added to a total amount of 1555 g, and 445 ml of an aqueous solution containing 4 wt% of chrome alum and 0.67 wt% of phthalic acid was applied with a static mixer immediately before application. The mixture was used as a coating solution for the surface protective layer, and was fed to a coating die so as to have a concentration of 10 ml / m ² . The viscosity of the coating solution was 9 mPa · S using a B-type viscometer at 40 ° C. (using a No. 1 rotor).

<< Preparation of Back Surface Coating Solution >> (Preparation of Solid Precursor Dispersion of Base Precursor) 64 g of a base precursor compound and 10 g of a surfactant Demol N manufactured by Kao Corporation were mixed with 246 ml of distilled water. Beads are dispersed using a sand mill (1/4 Gallon sand grinder mill, manufactured by AIMEX Co., Ltd.), and the average particle size is 0.2 μm.
m of a solid fine particle dispersion of a base precursor was obtained.

(Preparation of Dye Solid Fine Particle Dispersion) 9.6 g of a cyanine dye compound and 5.8 g of sodium p-alkylbenzenesulfonate were mixed with 305 ml of distilled water, and the mixed solution was subjected to a sand mill (1/4 Gallon sand grinder mill, Amimex Co., Ltd.). )) To disperse the beads to obtain an average particle diameter of 0.
A dye solid fine particle dispersion of 2 μm was obtained.

(Preparation of Coating Solution for Thermal Decoloring Antihalation Layer) 17 g of gelatin, 9.6 g of polyacrylamide, 70 g of solid fine particle dispersion of the above base precursor, 56 g of solid fine particle dispersion of the above dye, and polymethyl methacrylate fine particles (average particle (Size 6.5 μm) 1.5 g, 2.2 g of sodium polyethylene sulfonate, 0.2% 1% aqueous solution of coloring dye compound
g and H ₂ O were mixed to prepare an antihalation layer coating solution.

(Preparation of Coating Solution for Protective Layer) The container was kept at 40 ° C., gelatin 50 g, polystyrene sodium 0.2 g, N, N′-ethylenebis (vinylsulfone acetamide) 2.4 g, t-octylphenoxyethoxyethane Sodium sulfonate 1g, Benzoisothiazolinone 30m
_{g, C 8 F 17 SO 3} K to _{32mg, C 8 F 17 SO 2} N (C 3 H 7) (CH 2 CH 2 O) 4 (C
H _{2) 4} -SO ₃ Na and 64 mg, and a protective layer coating liquid was 950ml mixing H ₂ O.

[0149]

Embedded image

<< Preparation of Photothermographic Material >> On the undercoated support, the coating amount of the antihalation layer was 0.04 g / m ² , and the coating amount of the protective layer was gelatin. 1g / m ² was coated simultaneously and dried to form an antihalation back layer, and then the emulsion layer, intermediate layer and protective layer were placed on the opposite side of the back side from the undercoating side.
A layer of the heat-developable photosensitive material was prepared by simultaneously applying a layer and a protective layer in the order of the second layer by a slide bead coating method. After coating the back surface, the emulsion surface was coated without winding.

The coating was performed at a speed of 160 m / min, the distance between the tip of the coating die and the support was set to 0.18 mm, and the pressure in the decompression chamber was set 392 Pa lower than the atmospheric pressure. In the subsequent chilling zone, air with a dry-bulb temperature of 18 ° C and a wet-bulb temperature of 12 ° C is blown at an average wind speed of 7 m / s for 30 seconds to cool the coating liquid, and then a helical floating type drying zone A dry air having a dry-bulb temperature of 30 ° C. and a wet-bulb temperature of 18 ° C. was blown out from the holes at an air velocity of 20 m / sec for 200 seconds to volatilize the solvent in the coating solution.

The photothermographic materials were prepared as described above, and Sample Nos. 1 to 8 were obtained.

(Evaluation of photographic performance) After exposing the photographic material with a laser sensitometer equipped with a 660 nm diode,
After processing (developing) at 122 ° C. for 19 seconds, the obtained image was evaluated using a densitometer. The environment during exposure and thermal development is
Each device was placed in a constant temperature and humidity chamber, and the humidity during exposure and during development was changed. The result of the measurement evaluated the sensitivity.
The sensitivity was represented by a reciprocal of an exposure amount giving a density higher than Dmin by 2.0 as a relative value. For each sample, the sensitivity when the humidity during exposure and heat development is the same is 100, and the sensitivity when the humidity difference between exposure and heat development is 30% RH, 20% RH, and 10% RH is 0%. Table 1 shows the absolute value of the relative sensitivity difference as compared with the sensitivity at the time.

Table 1 ─────────────────────────────────── Sample Iridium addition amount Exposure time and development time Sensitivity difference due to humidity difference No.g / AgX1mol △ 30% RH △ 20% RH △ 10% RH ──────────────────────────── ─────── 1 1 × 10 ^-8 550 154 120 2 1 × 10 ^-7 400 125 115 3 1 × 10 ^-6 370 123 113 4 1 × 10 ^-5 280 116 107 5 1 × 10 ^-4 230 115 105 6 1 × 10 ^-3 225 113 104 7 1 × 10 ^-2 350 155 115 8 None 350 160 117 ───────────────────────── ──────────

Good results were obtained in the region of the present invention.

[0156]

According to the present invention, there is provided an image forming method using a photothermographic material capable of always obtaining a constant photographic characteristic with respect to fluctuations in environmental conditions.

Claims (2)

[Claims] 1. A method for forming an image by imagewise exposing a photothermographic material containing an organic silver salt, a reducing agent for silver ions, a polymer binder and a photosensitive silver halide on a support, followed by heat development. In, the humidity when the photosensitive material is exposed,
An image forming method, wherein a difference in humidity during heat development is 20% RH or less. 2. The image forming method according to claim 1, wherein the photosensitive silver halide contains an iridium compound and is chemically sensitized.