JP3240525B2 - Photothermographic material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photothermographic material, and more particularly to a photothermographic material capable of obtaining a high maximum density and having excellent development stability.

[0002]

BACKGROUND OF THE INVENTION Photothermographic materials in which the developing step is carried out by heating are known, and those which produce black-and-white images and color images are known. Further, a so-called transfer type photothermographic material which transfers an image obtained by thermal development from a photosensitive material to a dye image receiving layer is also well known. The photothermographic material usually has, on a support, at least one photosensitive layer containing a binder, a photosensitive silver halide emulsion, a reducing agent, and, if necessary, a dye-donating substance and an organic silver salt.

In a transfer type heat-developable color light-sensitive material, the light-sensitive material has an image-receiving layer capable of receiving silver or a dye, and has a separate image-receiving layer capable of receiving silver or a dye separately from the light-sensitive material. An image receiving material may be used in combination. The present invention relates to such a photothermographic material.

In the photothermographic material, an organic silver salt has been conventionally preferably used because it serves as a supply source of silver ions to shorten the developing time, increase the maximum density, and provide a high contrast effect. Among them, for example, JP-B-43-4921, JP-A-49-49
52626, 52-141222, 53-36224, 53-37626
Nos. 53-36224, 53-37610 and U.S. Pat.Nos. 3,330,633, 3,794,496, and 4,105,451.A silver salt of a long-chain aliphatic carboxylic acid described in, for example, US Pat. Silver salts of carboxylic acids (e.g., silver behenate, α-
(1-Phenyltetrazolethio) silver acetate, etc.) or JP-B-44-26582, JP-B-45-12700, JP-B-45-18416, and JP-B-45-228
No. 15, JP-A-52-137321, JP-A-58-118638, JP-A-58-11863
No. 9, US Pat. No. 4,123,274 and the like, silver salts of compounds having an imino group, acetylene silver described in JP-A-61-249044 and the like have been preferably used.

As a method for preparing these organic silver salts, for example, an organic silver salt is prepared as described in Examples of JP-A-49-52626.
After isolation, a method of mixing in a solvent, JP-A-62-78555
No. 63-259651 No. 63-259651 A method of preparing and isolating an organic silver salt as described in Examples, and then mechanically pulverizing and dispersing it into solid fine particles, JP-A-52-141222, JP-A-53-36224. , 53-37610
A method of performing centrifugal separation and washing operation on organic silver salt particles obtained by adding a silver ammonia complex salt aqueous solution to a raw material organic compound solution as described in Example No. and then dispersing the particles in a hydrophilic polymer, As described in JP-A-54-130019, a method is known in which an organic silver salt is pulverized by passing it through a supersonic gas stream and then dispersed in a dispersion medium. Further, as described in JP-A-1-100177, an organic silver salt dispersion obtained by adding a silver nitrate aqueous solution to a raw material organic compound dissolved in a hydrophilic colloid aqueous solution is p
There is also known a method in which H is precipitated by controlling H to remove soluble salts, and the like.

The use of an organic silver salt prepared as described above has a favorable effect on so-called developability such as an increase in the maximum density and a high contrast. Variations in gradation were likely to occur with respect to variations in time and time. For this reason, the above disadvantages are improved,
It has been desired to develop a photothermographic material having a high maximum density and excellent development stability against variations in the temperature and time of heat development.

[0007]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a heat-developable color light-sensitive material which has solved the above-mentioned problems. That is, an object of the present invention is to provide a photothermographic material capable of obtaining a high maximum density and having excellent development stability.

[0008]

The object of the present invention is to provide a photothermographic material having a photosensitive silver halide, a binder, a reducing agent and an organic silver salt on a support, wherein the average particle size of the organic silver salt particles is r. , Where σ is the standard deviation in the particle size distribution,
/ R is 0.5 or less.

Hereinafter, a specific configuration of the present invention will be described in detail.

The average particle size r of the organic silver salt particles in the present invention
Is defined as the diameter of the circular image when the projected image of the organic silver salt particles is converted into a circular image having the same area. Further, when the standard deviation in the particle size distribution is σ, the σ / r is adjusted to be 0.5 or less.

Conventionally, when organic silver salt particles are used in a photothermographic material, when the temperature or time of thermal development varies (so-called process variation), the gradation of the resulting image tends to vary. there were.

According to the study of the present inventors, it has been found that by preparing the organic silver salt particles so that σ / r is 0.5 or less as described above, it is possible to reduce the variation in gradation when the processing is varied. did.

The organic silver salt particles are considered to contribute to the improvement of developability by silver ions generated by dissolution of a part of the organic silver salt particles in the photothermographic material at the time of thermal development. It is believed to vary depending on the nature of the particles, such as particle size, shape, composition and the like. In the present invention, by controlling the particle size distribution of the organic silver salt particles to be narrow, the variation in the solubility of the organic silver salt particles during thermal development is reduced, and as a result, the variation in the gradation with respect to the processing variation is reduced. It is estimated that the reduction was achieved.

In the present invention, the organic silver salt particles preferably have an average particle diameter r of 0.1 μm or more and 0.8 μm or less.
When the average particle size is 0.8 μm or more, the variation in the maximum density with respect to the variation in the developing temperature tends to increase, and aggregation of organic silver salt particles as nuclei tends to occur when the coating solution is stagnated. On the other hand, when the average particle size is 0.1 μm or less, desensitization during storage of the photothermographic material is likely to be large, and foaming is likely to occur during preparation of the organic silver salt dispersion, which is likely to cause inconvenience in the process. .

As a method for preparing the dispersion of the organic silver salt particles used in the present invention, conventionally known methods can be used in combination. For example, after dissolving and mixing silver nitrate and a starting organic compound in water or an organic solvent such as methanol, the organic silver salt is isolated, and then pulverized and dispersed by means of a high-speed stirrer, a ball mill, a sand mill, a colloid mill, a vibration mill, or the like. Then, it can be used after being adjusted to a desired particle size distribution by centrifugation, pressure filtration or the like. However, in such a preparation method, it is difficult to control the particle size at the time of pulverization and dispersion, and the productivity is poor. Therefore, after preparing while controlling the particle size and distribution of the organic silver salt particles in a hydrophilic colloid aqueous solution, It is preferable to prepare a dispersion having a desired particle size and particle size distribution by a method for removing soluble salts.

Hereinafter, a method for preparing organic silver salt particles in a hydrophilic colloid aqueous solution will be described in more detail.

To prepare organic silver salt particles in an aqueous solution of hydrophilic colloid, a water-soluble silver salt is reacted with a raw material organic compound, and a conventionally known method can be used as a mixing method. For example, a method in which a raw material organic compound solution is put in a reaction vessel in advance, and a water-soluble silver salt solution is added thereto, or conversely, a water-soluble silver salt solution is put in a reaction solution in advance, and the raw material organic compound solution is put here. A method of adding a compound solution may, for example, be mentioned.

However, in order to control the particle size and the particle size distribution, a part of the raw material organic compound is put in a reaction vessel, and the water-soluble silver salt solution and the raw material organic compound are simultaneously added thereto while being controlled. Is preferred.
In any case, it is preferable to stir during the reaction to keep the inside of the reaction vessel uniform.

In the present invention, the preparation of the organic silver salt particles is preferably carried out in an aqueous solution of hydrophilic colloid in order to improve the dispersion stability of the formed silver salt particles. May be added to
Also, it may be added to the raw material organic compound solution, or may be added to both.

The concentration of the hydrophilic colloid during the reaction differs depending on the particle size of the organic silver salt particles to be prepared.
Preferably, it is in the range of 0.1 to 250 g per liter.
Examples of the hydrophilic colloid include gelatin and its derivatives, graft polymers of gelatin and other polymers, albumin, casein, cellulose and its derivatives, starch,
Natural and synthetic hydrophilic high molecular substances such as polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, polyacrylamide, polyvinyl butyral, kelcogel, kappa carrageenan, iota carrageenan and the like can be used.

The reaction is preferably carried out at a temperature of 10 to 90 ° C. When the raw material organic compound and the water-soluble silver salt are mixed to react with each other, it is preferable that the raw material organic compound is mixed in a ratio of 0.7 to 50 mol per 1 mol of silver. In order to obtain a desired particle size and particle size distribution, it is preferable to control the silver ion concentration and the pH during the reaction, and for that purpose, the addition rate of the water-soluble silver salt solution and the raw material organic compound solution may be adjusted. . It is also possible to add an acid or a base for controlling the pH.

As the water-soluble silver salt solution, aqueous solutions of various water-soluble silver salts can be used, and examples thereof include an aqueous solution of silver nitrate, an aqueous solution of silver sulfate, and an aqueous solution of silver acetate.

The above-mentioned organic silver salt particle forming reaction can also be carried out in the presence of a compound known as a silver halide solvent such as ammonia, thiocyanic acid and organic thioether. The amount of the compound that can be used as a silver halide solvent is preferably in the range of 1 × 10 ⁻⁴ mol to 1 mol per mol of silver. Also, salts such as sodium nitrate and ammonium sulfate can be used to control the particle size.

After the formation of the organic silver salt particles, it is preferable to perform so-called desalting for removing unnecessary soluble salts. As the desalting method, conventionally known methods can be used, for example, a method using a combination of a precipitation aid / polyvalent ion described in Japanese Patent Application No. 1-313206, an aggregated gelatin agent having an amino group modified, And a method using an aggregated polymer agent.
However, in order to prevent a decrease in sensitivity during storage and an increase in fog, it is preferable to use an aggregated gelatin agent or an aggregated polymer agent in which an amino group is modified. When using an aggregated gelatin agent or an aggregated polymer agent in which the amino group is modified, in particular, after the formation of the organic silver salt particles, a part or all of them are added before the start of desalting, and the amino group at the time of particle formation is reduced. A method of desalting in an amount larger than the amount of the modified aggregated gelatin agent or aggregated polymer agent is preferred.

The dispersion of the organic silver salt particles is preferably used after adjusting the pH to 5.0 to 9.0 in order to prevent an increase in fog and a decrease in the maximum density.

The composition of the organic silver salt particles is selected according to the intended use. For example, JP-B-43-4921 and JP-A-49-49
52626, 52-141222, 53-36224, 53-37626
Nos. 53-36224 and 53-37610 and U.S. Pat.
Nos. 330,633, 3,794,496, 4,105,451, etc., silver salts of long-chain aliphatic carboxylic acids and silver salts of carboxylic acids having a heterocyclic ring (for example, silver behenate, α- (1-phenyltetrazolethiol) ) Silver acetate, etc.)
-26582, 45-12700, 45-18416, 45-22815
No., JP-A-52-137321, JP-A-58-118638, JP-A-58-118639
And silver salts of compounds having an imino group described in US Pat. No. 4,123,274 and the like, silver acetylene described in JP-A-61-249044, and the like are preferably used.

Particularly preferred are silver salts of compounds having an imino group, for example, silver salts of benzotriazole and its derivatives.
(Eg, silver benzotriazole, silver 5-methylbenzotriazole, etc.) are particularly preferred.

The above-mentioned organic silver salts can be used alone or in combination of two or more. However, it is preferable to use them alone from the viewpoint of development stability.

As the photosensitive silver halide used in the photothermographic material of the present invention, conventionally known photosensitive silver halides can be used, for example, silver chloride, silver bromide, silver iodobromide, silver chlorobromide, Silver chloroiodobromide can be used.

The silver halide may have a uniform composition from the inside to the surface of the grain, or may have a composition that changes continuously or stepwise between the inside and the surface.

The shape of the silver halide may be one having a distinct crystal habit such as tabular, cubic, spherical, octahedral, dodecahedral, or tetrahedral or the like.

Further, for example, US Pat. Nos. 2,592,250 and 3,2,250
20,613, 3,271,257, 3,317,322, 3,511,62
No. 2, 3,531,291, 3,447,927, 3,761,266,
Internal latent image type silver halide emulsions described in JP-A Nos. 3,703,584, 3,736,140, 3,761,276, JP-A-52-15661, and JP-A-55-127549 can be used.

In the photosensitive silver halide, metal ion species such as iridium, gold, rhodium, iron, and lead can be added in a suitable salt form at the stage of grain formation.

The photosensitive silver halide emulsion has a particle size of about 0.1.
02 to 2 μm, preferably about 0.05 to 0.5 μm.

In the present invention, as a method for preparing a photosensitive silver halide, a photosensitive silver salt-forming component such as a water-soluble halide is allowed to coexist with an organic silver salt described later, and a part of the organic silver salt is subjected to photosensitive halide. It can also be formed by converting to a part of silver.

The photosensitive silver halide emulsion is a known sensitizer.
(E.g., active gelatin, inorganic sulfur, sodium thiosulfate, thiourea dioxide, sodium chloroaurate, etc.) can chemically sensitize the surface of silver halide grains, and use a nitrogen-containing heterocyclic compound or a mercapto group-containing heterocyclic compound. Chemical sensitization can also be performed in the presence of a compound.

Further, the photosensitive silver halide can be subjected to spectral sensitization to blue, green, red, and near-infrared light with a known spectral sensitizing dye such as cyanine and merocyanine used in ordinary photography.

These sensitizing dyes are used in an amount of 1 μmol to 1 mol, preferably 10 μmol to 0.1 mol, per mol of silver halide when forming silver halide grains, when removing soluble salts, before starting chemical sensitization, and during chemical sensitization. , Or at any time after completion of chemical sensitization.

The photothermographic material of the present invention is used as a black-and-white or color photographic material. When used as a color photographic material, a dye-providing substance is used.

Examples of the dye-donor include, for example, JP-A-61-6
No. 1157, No. 61-61158, No. 62-44738, No. 62-129850
Nos. 62-19851, 62-19852, 62-169158, and couplers forming diffusible dyes described in JP-A-3-73949, for example, described in JP-A-61-88254. Or the azo dye described in U.S. Pat.No. 4,235,957, or U.S. Pat.Nos. 4,463,079, 4,439,513, JP-A-59-60434, JP-A-59-65839, JP-A-59-71046, and JP-A-59-71046. 59-874
No. 50, No. 59-123837, No. 59-124329, No. 59-165054
And a dye-providing substance having a reducing property with respect to silver halide described in JP-A Nos. 59-165055. In particular, a compound which forms a diffusible dye by a coupling reaction is preferable, and is, for example, a compound represented by the general formula (A) on page 9, lower left column, second line, page 9 of JP-A-2-863. Among them, a polymer coupler having a polymer chain having a repeating unit derived from a monomer represented by the general formula (b) described in the right column of the lower right column on page 9 of the same publication is preferable.

Examples of the positive dye-providing substances include, for example, JP-A-59-55430, JP-A-59-165054, JP-A-59-154445, and JP-A-59-154445.
-116655, 59-124327, 59-152440, 59-1805
Nos. 48, 60-244947, and 64-13546.

The above dye-providing substances may be used alone or in combination of two or more.

The photothermographic material of the present invention is, for example,
JP-A-2-293753 and JP-A-2-308162, together with a polymerizable compound, a dye-providing substance is contained in a microcapsule, and the polymer is heat-developed to imagewise or reversely polymerize the polymerizable compound. The present invention can also be applied to a photothermographic material of a type in which an image is formed to cure a microcapsule and change the diffusibility of a dye-providing substance into an image receiving layer to form an image.

The reducing agent used in the photothermographic material of the present invention is selected from those conventionally known for photothermographic materials by a developing mechanism and a dye formation / release mechanism. The reducing agent mentioned here includes a reducing agent precursor that releases the reducing agent during thermal development.

Examples of the reducing agent that can be used in the present invention include, for example, US Pat.
Nos. 761,270, 3,764,328, 3,342,599,
No. 3,719,492 and Research Disclosure 12,146
No. 15,108, 15,127 and JP-A-56-27132,
53-135628, p-phenylenediamine-based and p-aminophenol-based developing agents, phosphoramidophenol-based developing agents, sulfonamidoaniline-based developing agents, and hydrazone-based developing agents described in No. 57-79035, phenols ,
Sulfonamidophenols, polyhydroxybenzenes, naphthols, hydroxybisnaphthyls, methylenebisphenols, ascorbic acids, 1-aryl
-3-pyrazolidones and precursors of the various reducing agents described above.

Further, the dye-providing substance can also serve as a reducing agent.

Particularly preferred reducing agents are N- (pN ', N'-dialkylamino) phenylsulfamate and its derivatives described in JP-A-56-146133 and JP-A-62-227141.
Specifically, Japanese Patent Application Laid-Open No. 2-863, page 7, lower left column, line 6 to 8
The compounds described in the lower right column of the page can be mentioned.

A thermal solvent can be used in the photothermographic material of the present invention for the purpose of accelerating the transfer of a dye and for other purposes. The thermal solvent is a compound which is liquefied during thermal development and has an action of promoting thermal development and thermal transfer of a dye, and is preferably in a solid state at normal temperature.

Examples of the thermal solvent that can be used in the present invention include, for example, US Pat. Nos. 3,347,675, 3,667,959,
No. 438,776, No. 3,666,477, Research Disclosure No. 17,643, JP-A-51-19525, No. 53-24829, No. 53-6
0223, 58-118640, 58-198038, 59-229556
No. 59-68730, No. 59-84236, No. 60-191251, No. 6
0-232547, 60-14241, 61-52643, 62-78554
No. 62-42153, No. 62-44737, No. 63-53548, No. 63
-161,446, JP-A 1-224751, 2-863, 2-20173
No. 9, No. 2-123354 and the like.

Specifically, urea derivatives (urea, dimethylurea, phenylurea, etc.), amide derivatives (eg, acetamido, stearylamide, p-toluamide, p-propanoyloxyethoxybenzamide, etc.), sulfonamide derivatives (eg, -Toluenesulfonamide, etc.) and polyhydric alcohols (eg, 1,6-hexanediol, pentaerythritol, polyethylene glycol, etc.) are preferably used.

The above thermal solvent is a photosensitive silver halide emulsion layer,
It can be added to any layer such as an intermediate layer, a protective layer, or an image receiving layer of an image receiving material, and the amount of addition is usually from 10% by weight to 500% by weight, more preferably from 20% by weight to 2% by weight, based on the binder.
00% by weight.

Examples of the binder which can be used in the photothermographic material of the present invention include, for example, JP-A-2-863.
The binders described in the upper right column, line 14 to the lower left column, line 10 of the page can be used including preferred combinations.
Particularly preferred binders are gelatin, polyvinylpyrrolidone, polyethylene glycol, and combinations thereof.

Various additives can be added to the photothermographic material of the present invention, if necessary, in addition to the above.

As the development accelerator, for example, JP-A-59-177
No. 550, No. 59-111636, No. 59-124333, No. 61-72233
No. 61-236548, No. 61-159642, JP-A-1-152454
Development accelerator releasing compounds described in JP-A Nos. 1-104645 and 3-67256 or metal ions having an electronegativity of 4 or more described in JP-A-1-274130 can also be used.

As antifoggants, for example, US Pat.
Higher fatty acids described in 645,739, JP-B-47-1111
No. 3, mercury salts described in No. 3, N-halides described in JP-A-51-47419, U.S. Pat. No. 3,700,457 and JP-A-51-50725
No. 2,294,548, mercapto compound-releasing compound described in 2-282241, arylsulfonic acid described in JP-A-49-125016, lithium carboxylate described in 51-47419, UK patent No. 1,455,271 and JP-A-50-101019
No. 53-19825, sulphinic acids and thiosulfonic acids, No. 51-3223, Thiouracils, No. 51-26019, Sulfur, No. 51-42529, No. 51-81124.
And disulfides and polysulfides described in JP-A-55-93149, rosin or diterpenes described in JP-A-51-57435, polymer acids having a carboxyl group or a sulfonic acid group described in JP-A-51-104338, and US Pat. No. 4,138,265. Thiazolythion, JP-A-54-51,821, 55-142,33
No. 1, triazoles described in U.S. Pat.No.4,137,079, thiosulfinic acid esters described in JP-A-55-140883,
JP-A-59-46641, JP-A-59-57233, di- or tri-halides described in JP-A-59-57234, thiol compounds described in JP-A-59-111636, JP-A-60-198540 and JP-A-60-227255 Hydroquinone derivatives described in JP-A-62-78554, antifoggants having a hydrophilic group described in JP-A-62-78554, polymer antifoggants described in JP-A-62-121452, ballast groups described in JP-A-62-123456 And a colorless coupler described in JP-A-1-61239.

As the base precursor, for example, those described in
56-130745, 59-157637, 59-166943, 59-1805
No. 37, No. 59-174830, No. 59-195237, No. 62-108249
No. 62-174745, No. 62-187847, No. 63-97942, No.
63-96159, JP-A-1-68746 and the like, and the compounds or base releasing technologies described in each publication.

Various known photographic additives other than those described above can be used in the photothermographic material of the present invention. Examples thereof include antihalation dyes, antiirradiation dyes, colloidal silver, fluorescent whitening agents, It may contain a hardening agent, an antistatic agent, a surfactant, an inorganic or organic matting agent, an anti-fading agent, an ultraviolet absorber, an antifungal agent, a white color tone adjusting agent and the like. These are described in, for example, Research Disclosure Nos. 17029 and 29,963, and JP-A-62-135825.
And Nos. 64-13546. Especially JP-A-63
Contaminants such as halogen-substituted heterocyclic compounds described in JP-A-118155, halogen-substituted aliphatic compounds described in JP-A-3-223852, and activated carbon described in JP-A-2-44356. It is preferable to contain an adsorbing substance to be adsorbed.

These various additives can be appropriately added not only to the photosensitive layer but also to any constituent layer such as an intermediate layer, an undercoat layer, a protective layer or a backing layer.

As the support used in the photothermographic material of the present invention, for example, those described in JP-A-2-863, page 12, upper left column, line 15 to upper right column, line 1 can be used.

Preferably, a polyethylene terephthalate support or a paper support such as cast-coated paper or baryta paper is used.

The photothermographic material of the present invention contains (a) a photosensitive silver halide emulsion, (b) a reducing agent, (c) a binder, and (d) organic silver. (E)
Contains a dye-providing substance. These may be contained in a single photographic component layer, or may be added separately in two or more layers.

The photosensitive layers having substantially the same color sensitivity can be composed of two or more photosensitive layers, and can be a low-sensitivity layer and a high-sensitivity layer, respectively.

When the photothermographic material of the present invention is used as a full-color recording material, it usually has three photosensitive layers having different color sensitivities, and a dye having a different hue is formed in each photosensitive layer by thermal development. Or released. in this case,
Generally, a yellow dye (Y) is contained in the blue photosensitive layer (B), a magenta dye (M) is contained in the green photosensitive layer (G), and a red photosensitive layer is provided.
The cyan dye (C) is combined with (R), but the present invention is not limited to this, and any combination is possible. Specifically, (BC)-(GM)-(RY), (infrared-sensitive-C)-(G
Combinations such as -Y)-(RM) are also possible.

The layer constitution of each layer is arbitrary, and layer arrangement such as RGB, GRRB, RG-infrared, GR-infrared can be employed in this order from the support side.

The photothermographic material of the present invention may optionally have a non-photosensitive layer such as an undercoat layer, an intermediate layer, a protective layer, a filter layer, a backing layer, and a release layer in addition to the photosensitive layer. .

When the photothermographic material of the present invention is of a transfer type, an image receiving material is preferably used. The image receiving material is composed of an image receiving layer having a dye receiving ability provided on a support, but the support itself can also serve as an image receiving layer having a dye receiving ability.

The image receiving layer can be broadly divided into a case where the binder constituting the image receiving layer itself has a dye receiving ability and a case where a mordant capable of receiving a dye is contained in the binder.

When the binder has a dye-receiving ability, a substance preferably used has a glass transition temperature of about 40 ° C. or more,
It is preferably formed of a polymer having a temperature of about 250 ° C. or lower.Specifically, `` Polymer Handbook Second Edition '' (Joy Brand Wrap, edited by E.H.Inmargat), John Willy and Sons Publishing Co., Ltd. ｛Polymer Handbook 2nd.ed. (J. Brandrup.EHI
Synthetic polymers having a glass transition temperature of about 40 ° C. or higher described in John Wiley & Sons, edited by mmergut) are useful, and generally those having a molecular weight of about 2,000 to 200,000 are useful. These polymers may be used alone or in combination of two or more, or may be copolymerizable polymers having two or more types of repeating units.

Specifically, JP-A No. 2-863, page 14, upper left column 1
The polymers described from the fourth line to the upper right column, line 14 can be used, including preferred polymers.

In the image receiving material in which the image receiving layer contains a mordant in a binder, a polymer containing a tertiary amine or a quaternary ammonium salt is preferably used as the mordant. For example, US Pat. No. -13546. As a binder used for holding these mordants, a hydrophilic binder such as gelatin or polyvinyl alcohol is preferably used.

A dye-receiving layer obtained by dispersing a hydrophobic polymer latex having dye-receiving ability in a hydrophilic binder in the same manner as the image-receiving layer having the mordant in the binder can also be used in the present invention.

The image-receiving material of the present invention may have a single image-receiving layer provided on a support, or may have a plurality of constituent layers coated thereon. It may be an image receiving layer, or only a part of the constituent layers may be an image receiving layer.

When the image receiving material has a support separately from the image receiving layer, the support of the image receiving material may be either a transparent support or a reflective support, and is described in JP-A-2-863, page 14, lower left column. The support described in line 15 to line 8 in the lower right column and the second support
It can be used by selecting from a reflective support having seed diffuse reflection properties.

The photothermographic material of the present invention is disclosed in Research Disclosure No. 15,108, JP-A-57-198458 and JP-A-57-198458.
A so-called mono-sheet type photothermographic material in which a photosensitive layer and an image receiving layer as described in JP-A-207250 and JP-A-61-80148 and the like are previously laminated on the same support can also be used.

Various known additives can be added to the image receiving material of the present invention. Such additives include, for example, antifouling agents, ultraviolet absorbers, fluorescent brighteners, image stabilizers, development accelerators, antifoggants, pH adjusters (acid and acid precursors, base precursors, etc.), heat Examples thereof include solvents, organic fluorine compounds, oil droplets, surfactants, hardeners, matting agents, and various metal ions.

The photothermographic material of the present invention can be exposed by a known exposure means suitable for the color sensitivity of the photosensitive material.

As the exposure light source, JP-A-2-863
Those described in the 13th to 16th lines in the lower left column of the page can be used, and a laser light source, a CRT light source, and an LED are preferably used. In addition, a semiconductor laser and an SHG element (second
A light source in combination with a harmonic generation element) can also be used.

The exposure time differs depending on whether one screen is exposed by one exposure or digital exposure is performed for each pixel. In the former case, the exposure time is usually 0.001 to 10 seconds. This is performed within a range of 10 ^-8 to 10 ^-2 seconds per pixel.

At the time of exposure, the color temperature of the exposure light source can be adjusted using a color filter as necessary.
Scanner exposure can also be performed with a laser or the like. The photothermographic material of the present invention is preferably used after imagewise exposure or simultaneously with exposure, preferably at 70 to 200 ° C, more preferably at 90 ° C.
~ 170 ° C for preferably 1 to 180 seconds, more preferably 2 ~
Heat development is performed for 120 seconds to form a dye image.

The transfer of the diffusible dye to the image receiving material may be carried out simultaneously with the thermal development by bringing the image receiving layer surface of the image receiving material into close contact with the photosensitive layer side of the photosensitive material during thermal development. Alternatively, the dye may be transferred by bringing the image receiving material into close contact with the photosensitive material after the thermal development, or after supplying water, the photosensitive material and the image receiving material may be brought into close contact. Further, the photosensitive material may be preheated at a temperature of 70 to 160 ° C. before exposure, or at least one of the photosensitive material and the image receiving material immediately before development as described in JP-A-60-143338 and JP-A-61-162041. Can be preheated in a temperature range of 80 to 120 ° C.

When the photothermographic material of the present invention is thermally developed, known heating means can be applied. For example, JP-A-2-863, page 13, upper left column, lines 12 to 19 Method, a method using far-infrared heating, or the like can be used.

The heating pattern at the time of thermal development is not particularly limited, and a method of performing the development at a constant temperature, a method of performing the initial development at a high temperature and performing the latter half of the development at a low temperature, or vice versa, and further increasing the temperature in three or more steps Any method such as a method of changing the area or a method of continuously changing the temperature can be used.

[0083]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below. However, needless to say, the present invention is not limited by the embodiments described below.

Example 1 Preparation of Silver Benzotriazole Dispersion (OG-1) First, a benzotriazole silver salt was prepared using the following two kinds of solutions.

(Solution A-1) Silver nitrate 170 g 28% ammonia water 160 ml Finished to 1250 ml with ion-exchanged water (Solution B-1) Benzotriazole 132 g 28% ammonia water 800 ml Finished to 5000 ml with ion-exchanged water (Solution A-1) was added at a constant speed over 30 minutes while stirring at 800 rpm while keeping -1). Stir for an additional 10 minutes after the addition is complete, then add 56% aqueous acetic acid
The pH was adjusted to 7.0 and stirring was continued for another hour.

After completion of the stirring, the mixture was filtered and washed twice with water and dried to prepare a benzotriazole silver salt.

To 200 g of the benzotriazole silver salt thus obtained, 280 ml of a 5% aqueous solution of a phenylcarbamoylated gelatin having a weight average molecular weight of 140,000 and 90% of the amino groups of the gelatin blocked and 750 ml of ion-exchanged water were added. , The average particle size by dispersing with a ball mill disperser for 24 hours
0.5 μm σ / r = 0.85 benzotriazole silver salt dispersion
(OG-1) was prepared.

Preparation of Silver Benzotriazole Dispersion (OG-2) To 1230 g of the above benzotriazole dispersion (OG-1) was added 1.2 liters of ion-exchanged water, and 90% of the amino groups of the gelatin were phenylcarbamoyl groups. 130 ml of a 20% aqueous solution of the substituted denatured gelatin having a weight average molecular weight of 140,000 was added, and the mixture was stirred at 40 ° C. and 800 rpm for 15 minutes, adjusted to pH 5.0 with acetic acid, allowed to stand for 5 minutes, sedimented, and the supernatant was decanted.
Then, 2 liters of ion-exchanged water was added, the pH was adjusted to 6.0 with an aqueous potassium hydroxide solution, and the mixture was stirred for 10 minutes.
After standing for 10 minutes, the mixture was settled and the supernatant was decanted.
Finally, the pH is adjusted to 6. with deionized water and aqueous potassium hydroxide solution.
0, By finishing to a total volume of 1000 ml, average particle size 0.7μ
m, σ / r = 0.45 benzotriazole silver salt dispersion (OG
-2) was prepared.

Preparation of Benzotriazole Silver Salt Dispersion (OG-3) In the preparation of benzotriazole silver salt dispersion (OG-1), a surfactant (SA-1) was used in addition to an aqueous gelatin solution and ion-exchanged water during ball mill dispersion. ) Was added to a 5% aqueous solution, and the mixture was dispersed in a ball mill for 15 hours to prepare a benzotriazole silver salt dispersion (OG-3) having an average particle size of 0.9 μm and σ / r = 0.30.

Preparation of Benzotriazole Silver Salt Dispersion (OG-4) First, a benzotriazole silver salt was prepared using the following six kinds of solutions.

(Solution G-2) Ossein gelatin 125 g Benzotriazole 5.0 g 28% aqueous ammonia 21 ml Deionized water 1 liter (Solution A-2) Silver nitrate 150.0 g 28% aqueous ammonia 140 ml Finished to 590 ml with ion exchanged water B-2) Benzotriazole 104.0 g 28% ammonia water 71 ml Make up to 590 ml with ion-exchanged water (Solution C-2) 28% ammonia water pH adjustment required (solution D-2) 56% acetic acid aqueous solution pH adjustment required (solution E-2) Benzotriazole 95 g 28% ammonia water 80 ml Finish to 900 ml with ion-exchanged water At 50 ° C, use a mixing stirrer to (Solution A-2) while stirring with (Solution G-2) at 1000 rpm (Solution A-2). (B-2) was added at an equal flow rate by the double jet method.

The pH during the simultaneous mixing was (solution C-2) or
It was controlled at 9.3 by adding (Solution D-2).
Also, pAg was increased to 11.7 by adding (solution E-2).
Was controlled to be. (Solution A-2) and (Solution B-2) were added at a constant rate over 60 minutes, and the process was completed when (Solution A-2) was completely added. 130 ml of a 20% aqueous solution of phenylcarbamoylated gelatin having a weight average molecular weight of 140,000 in which 90% of the amino groups of the gelatin are blocked is added to the organic silver salt dispersion thus obtained, and the mixture is stirred at 800 rpm at 40 ° C. for 15 minutes. After adjusting the pH to 5.0 with acetic acid, the mixture was allowed to stand for 5 minutes, sedimented, and the supernatant was decanted. Then, 2 liters of ion-exchanged water was added, the pH was adjusted to 6.0 with an aqueous solution of potassium hydroxide, the mixture was stirred for 10 minutes, the pH was adjusted to 4.5 with sulfuric acid, and the mixture was allowed to stand for 10 minutes, sedimented, and the supernatant was decanted. Finally, the pH was adjusted to 6.0 with ion-exchanged water and an aqueous potassium hydroxide solution to a total volume of 1,000 ml to prepare a benzotriazole silver salt dispersion (OG-4) having an average particle size of 0.4 μm and σ / r = 0.62.

Preparation of Silver Benzotriazole Dispersion (OG-5) The same solutions as the six kinds of solutions used for the preparation of silver benzotriazole dispersion (OG-4) were prepared, and benzotriazole was prepared as follows. A triazole silver salt dispersion was prepared.

At 50 ° C., using a mixing stirrer (solution G-2) and stirring at 1200 rpm (solution A-2) and solution (B-2).
2) was added at an equal flow rate by the double jet method.

The pH during the simultaneous mixing was (solution C-2) or
It was controlled at 9.3 by adding (Solution D-2).
The pAg was controlled to 11.7 by adding (solution E-2). (Solution A-2) and (Solution B-2) were added at a constant rate over 60 minutes, and the process was completed when (Solution A-2) was completely added. 130 ml of a 20% aqueous solution of a modified gelatin having a weight average molecular weight of 140,000 in which 75% of the amino groups of the gelatin are substituted with a phenylcarbamoyl group is added to the organic silver salt dispersion obtained in this manner, and the mixture is stirred at 800 rpm for 15 minutes at 40 ° C The mixture was stirred, adjusted to pH 5.0 with acetic acid, allowed to stand for 5 minutes, allowed to settle, and the supernatant was decanted.

Next, 2 liters of ion-exchanged water was added, the mixture was stirred for 10 minutes at a pH of 6.0 with an aqueous potassium hydroxide solution, and the pH was adjusted to 4.5 with sulfuric acid. The mixture was allowed to stand for 10 minutes, sedimented, and the supernatant was decanted. Finally, the pH was adjusted to 6.0 with ion-exchanged water and an aqueous potassium hydroxide solution to a total volume of 1,000 ml to prepare a benzotriazole silver salt dispersion (OG-5) having an average particle size of 0.4 μm and σ / r = 0.25.

Preparation of Silver Benzotriazole Dispersion (OG-6) The same solutions as the six kinds of solutions used for the preparation of silver benzotriazole dispersion (OG-4) were prepared and benzotriazole was prepared as follows. A silver salt dispersion was prepared.

At 50 ° C., using a mixing stirrer (solution A-2) and the solution (B-2) while stirring at 1000 rpm (solution G-2).
2) was added at an equal flow rate by the double jet method. During the co-mixing, the pH was controlled to change from 11.3 to 10.3 sequentially by adding (Solution C-2) or (Solution D-2). The pAg can be reduced to 1 by adding (Solution E-2).
Controlled to be 1.7.

The addition of (Solution A-2) and (Solution B-2) was performed in a manner such that the addition increased linearly with the addition time in 45 minutes.
The process was completed when (Solution A-2) was completely added. 130 ml of a 20% aqueous solution of phenylcarbamoylated gelatin having a weight average molecular weight of 140,000 in which 75% of the amino groups of the gelatin are blocked is added to the organic silver salt dispersion thus obtained.
Stir at 800 rpm for 15 minutes at ℃, adjust the pH to 5.0 with acetic acid,
The mixture was allowed to stand for 5 minutes, allowed to settle, and the supernatant was decanted.

Next, 2 liters of ion-exchanged water was added, the mixture was stirred at pH 6.0 with an aqueous potassium hydroxide solution, stirred for 10 minutes, adjusted to pH 4.5 with sulfuric acid, allowed to stand for 10 minutes, allowed to settle, and the supernatant was decanted. Finally, the pH was adjusted to 6.0 with ion-exchanged water and an aqueous potassium hydroxide solution to a total volume of 1,000 ml to prepare a benzotriazole silver salt dispersion (OG-6) having an average particle size of 0.5 μm and σ / r = 0.21.

Preparation of Silver Benzotriazole Dispersion (OG-7) The same solutions as the six kinds of solutions used for the preparation of silver benzotriazole dispersion (OG-4) were prepared and benzotriazole was prepared as follows. A silver salt dispersion was prepared.

At 50 ° C., the solution (B-2) and the solution (B-2) were stirred with a mixing stirrer at 1000 rpm (solution G-2).
2) was added at an equal flow rate by the double jet method. During the co-mixing, the pH was controlled to change from 11.3 to 10.3 sequentially by adding (Solution C-2) or (Solution D-2). Also, pAg can be obtained by adding (Solution E-2).
Controlled to be 11.7. (Solution A-2) and (Solution B-
The addition of 2) was performed so as to increase linearly with the addition time in 45 minutes, and was completed when all of the solution A-2 was added.

The thus obtained organic silver salt dispersion is
After adjusting the pH to 5.5 with an aqueous solution of potassium carbonate, 1200 ml of a 5% aqueous solution of Demol N manufactured by Kao Atlas Co. and 800 ml of a 20% aqueous solution of magnesium sulfate were added, and the mixture was allowed to stand for 30 minutes to settle. After decanting the supernatant, 5000 ml of ion-exchanged water
Was added and stirred again for 20 minutes. Thereafter, 750 ml of a 20% aqueous solution of magnesium sulfate was added, the mixture was allowed to stand for 30 minutes, sedimented, and the supernatant was removed by decantation. Finally, the pH was adjusted to 6.0 and the total amount was adjusted to 1000 ml with ion-exchanged water and an aqueous potassium hydroxide solution to prepare a benzotriazole silver salt dispersion (OG-7) having an average particle size of 0.6 μm and σ / r = 0.35.

Preparation of Silver Benzotriazole Dispersion (OG-8) The same solutions as the six kinds of solutions used for the preparation of silver benzotriazole dispersion (OG-4) were prepared and benzotriazole was prepared as follows. A silver salt dispersion was prepared.

At 45 ° C., the solution (B-2) was mixed with the solution (B-2) while stirring at 1500 rpm using a mixing stirrer (Solution G-2).
2) was added at an equal flow rate by the double jet method. During the co-mixing, the pH was controlled to change from 11.3 to 10.3 sequentially by adding (Solution C-2) or (Solution D-2). Also, pAg can be obtained by adding (Solution E-2).
Controlled to be 11.7. (Solution A-2) and (Solution B-
The addition of 2) was performed so as to increase linearly with the addition time in 30 minutes, and was completed when all of the solution A-2 was added.

The organic silver salt dispersion thus obtained is
20% of denatured gelatin with weight average molecular weight of 140,000 in which 75% of amino groups of gelatin are substituted with phenylcarbamoyl group
130 ml of an aqueous solution was added, the mixture was stirred at 40 ° C. and 800 rpm for 15 minutes, the pH was adjusted to 5.0 with acetic acid, and the mixture was allowed to stand for 5 minutes, settled down, and the supernatant was decanted. Subsequently, 2 liters of ion-exchanged water was added, the mixture was stirred at an adjusted pH of 6.0 with an aqueous potassium hydroxide solution for 10 minutes, adjusted to a pH of 4.5 with sulfuric acid, allowed to stand for 10 minutes, allowed to settle, and the supernatant was decanted. Finally, the pH was adjusted to 6.0 with ion-exchanged water and an aqueous solution of potassium hydroxide to a total volume of 1,000 ml to prepare a benzotriazole silver salt dispersion (OG-8) having an average particle size of 0.08 μm and σ / r = 0.27.

Preparation of Silver Benzotriazole Dispersion (OG-9) The same solutions as the six kinds of solutions used for the preparation of silver benzotriazole dispersion (OG-4) were prepared as follows. A silver salt dispersion was prepared.

At 55 ° C., the solution (B-2) and the solution (B-2) were stirred at 1000 rpm using a mixing stirrer (Solution G-2).
2) was added at an equal flow rate by the double jet method. During the co-mixing, the pH was controlled to change from 11.3 to 10.3 sequentially by adding (Solution C-2) or (Solution D-2). The pAg can be reduced to 1 by adding (Solution E-2).
Controlled to be 1.7. (Solution A-2) and (Solution B-
The addition of 2) was performed so as to increase linearly with the addition time in 50 minutes, and was completed when all of the solution (solution A-2) was added.

The thus obtained organic silver salt dispersion is
After adjusting the pH to 5.5 with an aqueous solution of potassium carbonate, 1200 ml of a 5% aqueous solution of Demol N manufactured by Kao Atlas Co. and 800 ml of a 20% aqueous solution of magnesium sulfate were added, and the mixture was allowed to stand for 30 minutes to settle. After decanting the supernatant, 5000 ml of ion-exchanged water
Was added and stirred again for 20 minutes. Thereafter, 750 ml of a 20% aqueous solution of magnesium sulfate was added, the mixture was allowed to stand for 30 minutes, sedimented, and the supernatant was removed by decantation. Finally, a benzotriazole silver salt dispersion (OG-9) having an average particle size of 0.9 μm and σ / r = 0.35 was prepared by finishing the pH to 6.0 and the total amount to 1000 ml with ion-exchanged water and aqueous potassium hydroxide solution.

Preparation of Photosensitive Silver Halide Emulsion (Em-1) A silver iodobromide emulsion (Em-1) was prepared using the following five types of solutions.
1) was prepared. As a seed emulsion, a silver iodobromide emulsion (SE-1) having a silver iodide content of 2 mol% and an average grain size of 0.09 μm was used.

(Solution A-11) Ossein gelatin 3010 g 10% methanol solution of sodium salt of polyisopropylene-polyethyleneoxy-disuccinate 2000 ml 28% ammonia water 11.74 l seed emulsion (SE-1) 36.59 mol equivalent ion exchange Water 721 l (Solution B-11) Ossein gelatin 2100 g KBr 84 kg KI 2440 g Finished to 210 l with ion-exchanged water (Solution C-11) Silver nitrate 113.76 kg 28% ammonia water 90 l Finished to 191.3 l with ion-exchanged water (Solution D-11 ) 50% KBr aqueous solution pAg adjustment required (Solution E-11) 56% acetic acid aqueous solution pH adjustment required Using a mixing stirrer as described in JP-A-57-92523 and JP-A-57-92524 at 40 ° C. (Solution B-11) and (Solution C-
11) was added at an equal flow rate by the double jet method.

The flow rate of (Solution D-11) was controlled so that the pAg during simultaneous mixing was kept at 8.8.

The pH was adjusted to 8.0 at the start of the addition of (Solution B-11) and (Solution C-11), and then continuously changed by controlling the flow rate of (Solution E-11). At the end of the addition of (Solution B-11) and (Solution C-11), it was controlled to be 7.0.

The addition of (Solution B-11) and (Solution C-11) was performed at an allowable maximum speed (critical speed) at which no small particles were generated.
1) When 157.1 liters were added, 9.0 × 10 ^-5 mol of potassium hexachloroiridate (IV) (K ₂ IrCl ₆ )
Was added as an aqueous solution.

The addition of (Solution B-11) and (Solution C-11) was further continued until the addition of (Solution C-11) was completed.

Subsequently, with (Solution D-11) (Solution E-11), p
Ag 10.4 and pH were adjusted to 6.0. Next, 120 liters of a 5% aqueous solution of Demol N manufactured by Kao Atlas Co. and 80 liters of a 20% aqueous solution of magnesium sulfate were added as precipitants, and the particles were allowed to stand to stand.

Thereafter, the supernatant was removed by decantation and dispersed in an aqueous solution containing 9.2 kg of ossein gelatin.
After adding 42 g of the compound ST-2 shown below, the total amount was adjusted to 300 liters with distilled water, and further (solution D-11) (solution E-
The pAg was adjusted to 8.5 and the pH to 5.8 using 11).

Emulsion (Em-1) thus obtained
Is an average grain size of 0.25 μm, cubic, silver iodide content of 2 mol%
Was obtained as a monodispersed silver iodobromide emulsion.

Preparation of green light-sensitive silver halide emulsion (G-1) While keeping 150 liters of silver iodobromide emulsion (Em-1) at 56 ° C. and stirring, one of the following sensitizing dyes (SG-1) was prepared. 24 liters of a 10% methanol solution was added, and 10 minutes after the completion of the addition, 1800 ml of 0.5% sodium thiosulfate was added. After aging for 120 minutes while keeping the temperature at 56 ° C and stirring, the temperature was lowered to 40 ° C, and ion exchange was performed by adding 250 g of 4-hydroxy-6-methyl-1,3,3a, 7-tetraazaindene. The total amount was adjusted to 200 liters with water to prepare a green light-sensitive silver halide emulsion (G-1).

Preparation of Photothermographic Material A photothermographic material (1) having the following layer constitution was prepared on a photographic baryta paper support having a thickness of 160 μm.

Here, the amount of each material to be added depends on the photothermographic material 1
It is shown in an amount per m ² .

The addition amounts of the photosensitive silver halide emulsion and the silver benzotriazole emulsion were expressed in terms of silver.

Layer structure of photothermographic material Undercoat layer Polyphenylene ether resin 2.0 g Polystyrene resin 1.5 g Antifoggant-1 0.7 g First layer (emulsion layer) Benzotriazole silver salt dispersion (OG-1) 0.73 g Dye Donor (1) 2.0 g Green photosensitive silver halide emulsion (G-1) 0.80 g Gelatin 1.84 g Polyvinylpyrrolidone (K-90) 0.03 g DAP-1 0.2 g Hot solvent-1 1.5 g 1,10-diiododecane 0.10 g Antifoggant-2 0.02g Tricresyl phosphate 0.98g Hardener-1 0.09g Second layer (protective layer) Gelatin 0.9g Polyvinylpyrrolidone (K-90) 0.07g Reducing agent precursor-1 1.06g Diisodecyl phthalate 0.08g UV absorber-1 0.3g Zinc sulfate 0.4g Hardener-1 0.05g Silica powder 0.15g Antifoggant-2 0.01g

[0124]

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[0125]

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[0126]

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[0127]

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[0128]

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[0129]

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[0130]

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[0131]

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The above surfactant SA-2 was used as a coating aid for each layer.

In the production of the photothermographic material (1), the first
The photothermographic materials (2) to (9) were prepared by replacing the benzotriazole silver salt dispersion (OG-1) in the layer with the benzotriazole silver salt dispersions (OG-2) to (OG-9). .

Preparation of Dye-Receiving Material (A) A polyvinyl chloride layer containing the following compound was applied as an image-receiving layer on a photographic baryta paper support having a thickness of 180 μm. Was prepared.

Polyvinyl chloride (average degree of polymerization: about 900) 12 g Image stabilizer-1 0.8 g Image stabilizer-2 0.2 g Image stabilizer-3 0.2 g Image stabilizer-4 0.3 g Image stabilizer-5 0.1 g Image Stabilizer-6 0.2 g The following items were evaluated for the photothermographic materials (1) to (9). Table 1 shows the results of the evaluation.

(Evaluation of photographic performance) Photothermographic materials (1) to
(9) was exposed to green light of 1600 CMS using an interference filter KL-54 (manufactured by Toshiba Corporation) through a step wedge, and heat-developed at 150 ° C. for 60 seconds. Dye transfer was performed by heating at 130 ° C. for 30 seconds while being superimposed on the image receiving material (A). Thereafter, the photosensitive material and the image receiving material were peeled off to obtain a transferred image on the image receiving material.

The obtained dye image was subjected to density measurement using a reflection densitometer PDA65 (manufactured by Konica Corporation) to obtain a characteristic curve.

From this characteristic curve, the maximum density (Dmax) and the gradation (γ) between the reflection densities 0.5 and 1.0 were determined.

At 150 ° C., the heat development time was 57 seconds and 6 hours.
The maximum density and gradation when changed to 3 seconds, and further, the maximum density and gradation when the development temperature was changed to 147 ° C and 155 ° C in a heat development time of 60 seconds were obtained in the same manner.
It was expressed by the maximum density and the magnitude of change with respect to gradation (ΔD, Δγ) when heat development was performed at 60 ° C. for 60 seconds.

[0140]

[Table 1]

From the above results, it can be seen that the photothermographic material of the present invention has a high maximum density and a small change in the maximum density and gradation with respect to fluctuations in development time and development temperature.

Example 2 Preparation of Blue-Sensitive Silver Halide Emulsion (B-1) 150 liters of a silver iodobromide emulsion (Em-1) was heated at 56 ° C. and stirred while 633 ml of 0.5% sodium thiosulfate was added. Was added. The temperature was kept at 56 ° C as it was, and aging was continued for 200 minutes with stirring, then the temperature was lowered to 40 ° C and 4-hydroxy-6-methyl-1,
After adding 250 g of 3,3a, 7-tetraazaindene, the total volume was adjusted to 200 liters with ion-exchanged water to prepare a blue-sensitive silver halide emulsion (B-1).

Preparation of Red-Sensitive Silver Halide Emulsion (R-1) While keeping 150 liters of silver iodobromide emulsion (Em-1) at 56 ° C. and stirring, one of the following sensitizing dyes (SR-1) was prepared. 24 liters of a 10% methanol solution was added, and 10 minutes after completion of the addition, 867 ml of 0.5% sodium thiosulfate was added. After aging for 150 minutes while keeping the temperature at 56 ° C and stirring, the temperature was lowered to 40 ° C, and 250 g of 4-hydroxy-6-methyl-1,3,3a, 7-tetraazaindene was added. Replace all with 200
Then, a red-sensitive silver halide emulsion (R-1) was prepared.

Preparation of heat-developable color light-sensitive material A heat-developable color light-sensitive material (21) having the following layer constitution was prepared on a photographic baryta paper support having a thickness of 160 μm.

Here, the added amount of each material is shown per 1 m ² of the heat-developable color light-sensitive material.

The amounts of the light-sensitive silver halide emulsion and silver benzotriazole emulsion were expressed in terms of silver.

Layer structure of heat-developable color light-sensitive material Undercoat layer Polyphenylene ether resin 2.0 g Polystyrene resin 1.5 g Antifoggant-1 0.7 g First layer (red light-sensitive layer) Benzotriazole silver salt dispersion (OG-1) 0.4 g Dye-donating substance (3) 1.5 g Red-sensitive silver halide emulsion (R-1) 0.40 g Gelatin 1.0 g Polyvinylpyrrolidone (K-90) 0.02 g DAP-1 0.1 g Hot solvent-1 1.2 g 1,10- Diiododecane 0.10 g Antifoggant-2 0.02 g Anti-irradiation dye-2 0.02 g Tricresyl phosphate 0.4 g Hardener-1 0.05 g Second layer (middle layer) Gelatin 0.8 g Thermal solvent-1 0.3 g Polyvinylpyrrolidone ( K-90) 0.08g Reducing agent precursor-1 0.86g Diisodecyl phthalate 0.08g Ultraviolet absorber-1 0.1g Zinc sulfate 0.4g Hardener-1 0.05g Third layer (green photosensitive layer)
Benzotriazole silver salt dispersion (OG-1) 0.4 g Dye donating substance (1) 0.6 g Green photosensitive silver halide emulsion (G-1) 0.36 g Gelatin 1.0 g Polyvinylpyrrolidone (K-90) 0.02 g DAP-1 0.1g Hot solvent-1 1.2g 1,10-diiododecane 0.09g Antifoggant-2 0.03g Anti-irradiation dye-1 0.03g Tricresyl phosphate 0.3g Hardener-1 0.05g 4th layer (intermediate layer) Gelatin 0.8g Hot solvent-1 0.3g Polyvinylpyrrolidone (K-90) 0.08g Diisodecyl phthalate 0.08g Yellow filter dye-1 0.4g Ultraviolet absorber-1 0.1g Zinc sulfate 0.4g Hardener-1 0.05g No.5 Layer (blue photosensitive layer) Benzotriazole silver salt dispersion (OG-1) 0.6 g Dye-donating substance (2) 1.3 g Blue-sensitive silver halide emulsion (B-1) 0.61 g gelatin 1.4 g polyvinylpyrrolidone (K-90 ) 0.03g DAP-1 0.2g Thermal solvent-1 1.4g 1,10-diiododecane 0.10g Polyethylene glycol (MW = 2, 000) 0.22g Antifoggant-2 0.03g Tricresyl phosphate 0.3g Hardener-1 0.04g 6th layer (protective layer) Gelatin 0.4g Polyvinylpyrrolidone (K-90) 0.03g Reducing agent precursor-1 0.66g Diisodecyl phthalate 0.04 g Ultraviolet absorber-1 0.2 g Zinc sulfate 0.1 g Hardener-1 0.05 g Silica powder 0.1 g Antifoggant-2 0.01 g In each layer, surfactant SA-2 is used as a coating aid. did.

Preparation of heat-developable color light-sensitive materials (22) to (29) In the preparation of the heat-developable color light-sensitive material (21), a dispersion of silver salt of benzotriazole (OG-
1) The above benzotriazole silver salt dispersion (OG-2)
(OG-9) for heat-developed color photosensitive material
(22) to (29) were produced.

The following items were evaluated for the heat-developable color light-sensitive materials (21) to (29). Table 2 shows the results of the evaluation.

(Evaluation of photographic performance) Heat-developable color photosensitive material
Exposure to white light of 1600 CMS was performed on each of 30 sheets (21) to (29) through a step wedge.
10 seconds each for thermal development at 147 ° C. for 80 seconds and 155 ° C. for 70 seconds, and then superposed on the dye receiving material (A) for 130
Dye transfer was performed by heating at 45 ° C. for 45 seconds. Thereafter, the photosensitive material and the image receiving material were peeled off to obtain a transferred image on the image receiving material.

About the obtained dye image, a reflection densitometer PD
The concentration was measured using A65 (manufactured by Konica Corporation) to obtain a characteristic curve. From this characteristic curve, the maximum density (Dmax) and the gradation (γ) between the reflection densities 0.5 and 1.0 were determined. And 150 ° C
The average value of the maximum densities of 10 sheets subjected to heat development for 75 seconds at D is D, the difference between the maximum and minimum values of the maximum density in 30 samples is ΔD, and the difference between the maximum value and the minimum value of the gradation Was set to Δγ, and evaluated as a value indicating the degree of processing variation. The results obtained are shown in Table 2 below.

[0152]

[Table 2]

As is clear from Table 2, the photothermographic material of the present invention has a high maximum density and a small change in gradation or maximum density with respect to fluctuations in development time and temperature. Example 3 With respect to the photothermographic materials (1) to (9) produced in Example 1, the following items were evaluated.

(Evaluation of Storage Property of Photothermographic Material) The photothermographic materials (1) to (9) were stored at 40 ° C. in an atmosphere of RH 80% for 7 days, and exposed in the same manner as in Example 1. , 150 ℃, 60
After 2 seconds of heat development, the dye image-receiving material (A) was
Dye transfer was performed by heating at 0 ° C. for 30 seconds. Thereafter, the photosensitive material and the image receiving material were peeled off to obtain a transferred image on the image receiving material.

At this time, the difference between the Dmin before storage and the Dmin after storage (ΔDmin) and the sensitivity after storage with respect to the sensitivity before storage of each photosensitive material are shown by desensitization rate (%). It was evaluated as a value indicating the storage stability. The results obtained are shown in Table 3 below.

[0156]

[Table 3]

As can be seen from Table 3, particularly in the present invention, when the average particle size of the organic silver salt particles is 0.1 μm or more and 0.8 μm or less, fog rise and desensitization during storage of the photothermographic material are reduced. It can be seen that it can be reduced.

[0158]

According to the present invention, a high maximum concentration can be obtained,
In addition, a photothermographic material having excellent development stability was obtained.

Claims (3)

(57) [Claims] 1. A photothermographic material having a photosensitive silver halide, a binder, a reducing agent and an organic silver salt on a support, wherein the organic silver salt particles have a pH in an aqueous solution of hydrophilic colloid.
Control and adjust the pH of the organic silver salt particle dispersion.
Is produced by a method in which is adjusted to 5.0 to 9.0.
A photothermographic material, which is mechanical silver salt particles, wherein σ / r is 0.5 or less, where r is the average particle size, and σ is the standard deviation in the particle size distribution. 2. The photothermographic material according to claim 1, wherein the average particle size r of the organic silver salt particles is 0.1 μm or more and 0.8 μm or less. 3. The photothermographic material according to claim 1, wherein the organic silver salt particles are prepared by a method of removing soluble salts after adjusting in an aqueous solution of hydrophilic colloid.