JPH0572697A - Heat developable photosensitive material - Google Patents

Abstract

PURPOSE:To obtain a heat developable photosensitive material containing solid particles which effectively adsorb a coloring matter produced during thermal development and showing no degradation of storage property of the photosensitive material. CONSTITUTION:This heat developable photosensitive material contains at least a hydrophilic binder, photosensitive silver halide, dye-producing material which releases or forms a diffusive dye during thermal development, and solid particles which adsorb the dye material produced during thermal development. The film surface in the photosensitive layer side of the photosensitive material has pH5.5-8 at 25 deg.C.

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 having an improved minimum density (Dmin).

[0002]

BACKGROUND OF THE INVENTION A thermal development process in which a development process is performed by heating is known, and a process for obtaining a black and white image and a color image is known. Further, a so-called transfer type photothermographic material is also well known, which transfers an image obtained by heat development from the photographic material to the image receiving layer.

The photothermographic material usually has a binder, a photosensitive silver halide emulsion, a reducing agent, and, if necessary, a dye-donor substance, an organic silver salt and various other photographic additives on a support. is doing. Further, in the transfer type photothermographic material, there are a case where the photosensitive material has an image receiving layer capable of receiving silver or a dye and an image receiving material having an image receiving layer capable of receiving silver or a dye separately from the photosensitive material. May be used together.

In particular, when the photothermographic material is used as a photothermographic color photosensitive material, a method is used in which a dye image receiving material is used, and after the diffusible dye image is formed, the image dye is diffuse-transferred to the dye image receiving material. It is preferable from the viewpoint of obtaining a highly pure dye image.

Many methods and improved techniques for this method have been disclosed in the past.

When the diffusible dye image released or formed on the photothermographic material by heat development is diffuse-transferred to the image receiving material,
In the non-transfer portion, it is necessary to suppress the occurrence of fog and stain as much as possible in order to obtain a high-quality transferred image. Therefore, many antifoggants and antistain agents have been conventionally proposed.

Since the photothermographic material undergoes thermal development at a high temperature as compared with a conventional wet-processed photosensitive material, various stain substances are easily generated during the thermal development. Further, since the generated stain substance is transferred to the image receiving layer without being subjected to a process such as washing with water, it is easily transferred to the image receiving layer together with the image dye.

Japanese Unexamined Patent Publication (Kokai) No. 2-44356 discloses a technique in which a substance that adsorbs a coloring substance is added to a photothermographic material in advance in order to prevent the coloring substance generated during the heat development from being transferred to the image receiving layer. ing.

Specifically, the substance that adsorbs the coloring substance is
Activated carbon, ion exchange resin, silica gel and the like are described.

However, the addition of the above-mentioned coloring substance to the light-sensitive material can certainly reduce the coloring substance generated during heat development, but if it is left as it is, it has a remarkable drawback in other performance in terms of photographic performance. found.

That is, when the above-mentioned activated carbon, silica gel, or solid fine particles of ion-exchange resin are contained in advance in the photothermographic material, sensitizing dyes, development inhibitors or sensitizers for photographic use It was found that the additive was also absorbed. Adsorption of the sensitizing dye is remarkable especially when the photothermographic material is stored under high humidity conditions for a long period of time, and the sensitivity in the color sensitized region is significantly lowered.
This problem can be alleviated to some extent by adding an adsorbing substance to a non-photosensitive layer such as an intermediate layer, an undercoat layer or a protective layer, but it is not always sufficiently improved.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a photothermographic material containing solid particles which effectively adsorb a coloring substance formed during heat development. It is to provide a photothermographic material that does not deteriorate the storage performance.

[0013]

The above-mentioned object of the present invention is to provide at least a hydrophilic binder, a photosensitive silver halide, a dye-donor substance which releases or forms a diffusible dye during thermal development, and a coloring which occurs during thermal development on a support. A photothermographic material containing solid particles that adsorb a substance, wherein the film surface pH on the photosensitive layer side of the photothermographic material is 5.5 to 8 at 25 ° C. ..

The structure of the present invention will be described in detail below.

The solid particles for adsorbing the coloring substance produced during the heat development of the present invention include, for example, "Design of adsorbent / adsorption operation" (written by Hiroshi Yanai, published by Gihodo Publishing Co., Ltd., Showa 57).
Although the materials described on pages 1 to 10 can be used, specifically, silica gel, natural zeolite,
Synthetic zeolite, activated clay, bauxite, alumina,
Examples include activated carbon, metal-adsorbed carbon, and ion exchange resin. Preference is given to activated carbon, silica gel, natural and synthetic zeolites. Most preferred is activated carbon.

The solid particles that adsorb the coloring substance preferably have an average particle size of 0.05 to 2 μm, and preferably 0.1.
μm to 1 μm. Particularly preferably, it is 0.2 to 0.7 μm.

The solid particles for adsorbing the coloring substance of the present invention are
It can be added to any constituent layer of the photothermographic material, but in order to maximize the effects of the present invention, it is preferably added to the undercoat layer, the intermediate layer or the protective layer. The amount of solid particles added is 0.01 g per 1 m ^{2 of} photothermographic material.
~ 5g, preferably 0.02g-1g.

The adsorbed solid particles are added to the photothermographic material in the form of fine particles dispersed in a hydrophilic binder, and the particles are dispersed in a hydrophilic binder, preferably the undercoat layer, intermediate layer or protective layer. It is used by adding it to a coating solution for forming a layer).

Film surface of the photothermographic material of the present invention on the photosensitive layer side
It is necessary that the pH is 5.5 to 8 at 25 ° C.

The film surface pH on the side of the photosensitive layer referred to herein means a small amount of pure water dropped on the surface on the side of the photosensitive layer, and the spot is a plane pH.
It can be easily measured by applying an electrode. The pure water used here is ion-exchanged water or distilled water having its own pH of 5 to 8 and an electric conductivity of 1 μs / cm or less at 25 ° C. The small amount of pure water dropped on the surface of the photosensitive layer can be measured by dropping about 10 μl with a microsyringe and bringing a flat electrode into contact therewith.

In the photothermographic material of the present invention, it is necessary that the film surface pH on the photosensitive layer side is 5.5 to 8, but if the film surface pH is less than 5.5, it is due to the adsorbed solid particles. Desorption of the sensitizing dye increases, and the effect of the present invention cannot be obtained. On the other hand, when the film surface pH exceeds 8, when the photothermographic material is stored in a high humidity state, the fog is high even if the fog formation of the emulsion is increased and the stain due to the adsorbed solid particles is decreased. As a result, good white background cannot be obtained. In the present invention, the film surface pH of the photosensitive layer
Is preferably performed in the range of 6 to 7.5.

Film surface of the photothermographic material of the present invention on the photosensitive layer side
In order to bring the pH within the range of the present invention, generally, it can be carried out by appropriately adjusting the pH of the coating liquid for the various constituent layers on the photosensitive layer side. In that case, the coating liquids of the plurality of photosensitive layers may have the same value or different values. Further, in order to adjust the film surface pH on the side of the photosensitive layer within the range of the present invention, after coating all the constituent layers on the side of the photosensitive layer of the photothermographic material, a preadjusted value is applied to the surface. You may adjust the water solubility which it has by applying and drying.

The pH of the coating solution can be adjusted with a known acid or base. Specifically, it can be performed with an inorganic or organic acid such as sulfuric acid, nitric acid, hydrochloric acid or citric acid, or a base such as sodium hydroxide, potassium hydroxide, calcium carbonate or sodium carbonate. The above acids and bases can be used in combination, but the bright weak acids such as acetic acid and propionic acid, and the bright weak bases such as aqueous ammonia are evaporated after applying the coating liquid. In many cases, it is difficult to sufficiently control the pH of the membrane surface, and it is not very preferable as a substance that regulates pH.

The adsorbed solid particles used in the present invention are
When the particle surface is partially subjected to adsorption treatment with another substance in advance, the prevention of desorption of the sensitizing dye by the adsorbed solid particles is further reduced.

The term "adsorption treatment with other substances" as used herein means that a wide range of compounds such as plasticizers, cationic surfactants, anionic surfactants, nonionic surfactants, dyes and photographic additives are pre-adsorbed. Say what you want to keep. The compound to be adsorbed in advance is preferably an organic compound, and particularly preferably a photographic additive contained in the photosensitive layer of the photothermographic material. Above all, it is most preferable to partially adsorb a compound or an anionic surfactant which is adsorbed on silver halide in advance.

Known anionic surfactants can be used as the anionic surfactants to be adsorbed on such adsorbed solid particles in advance, and specifically, the following compounds can be used as examples. However, the anionic surfactant that can be used in the present invention is not limited to these.

[0027]

[Chemical 1]

[0028]

[Chemical 2]

[0029]

[Chemical 3]

Another preferable adsorbing compound to be adsorbed on the adsorbing solid particles in advance is one contained in the photosensitive layer and having adsorbing property to the silver halide grains, and a preferable compound having a mercapto group. Examples thereof include compounds, nitrogen-containing heterocyclic compounds, and sensitizing dyes.
The effect of the present invention is greatest when a sensitizing dye is adsorbed.

The amount of the compound pre-adsorbed on the adsorbed solid particles varies widely depending on the kind of the compound pre-adsorbed. When the substance to be adsorbed is an anionic surfactant,
0.1 to 10% by weight, preferably 0.5, based on the adsorbed solid particles
Used in the range of up to 5% by weight. If it exceeds 10%, the effect of adsorbing the coloring substance during heat development, that is, the effect of preventing contamination tends to be lowered.

When the substance to be adsorbed in advance is a sensitizing dye, the sensitizing dye is 0.001 to 1 with respect to the adsorbed solid particles.
%, Preferably 0.01 to 0.5% by weight.

The adsorbed solid particles may be adsorbed at any time before coating the photosensitive layer, but preferably adsorbed in advance before adjusting the coating liquid containing the adsorbed solid particles. Preferably. Specifically, it is preferable to add the adsorbed solid particles at the stage of dispersing them in a fine particle state, and to adsorb the adsorbed solid particles after being dispersed in the fine particle state and before adding to the coating liquid.

The photothermographic material of the present invention preferably contains a water-soluble halide with respect to the total photosensitive silver halide. Here, as the water-soluble halide,
It refers to a compound that releases a halogen ion when it itself becomes an aqueous solution, and specifically refers to a halogen compound such as sodium, potassium, magnesium, ammonium, zinc, calcium, or lithium.

The amount of the halide is preferably 0.2 to 10 mol% with respect to the total photosensitive silver halide emulsion contained in the photothermographic material. As the halogen compound, it is particularly preferable to add the amount of the water-soluble chloride among the above water-soluble halides in an amount of 0.5 mol% or more and 10 mol% or less with respect to the total photosensitive silver halide.

As the halogen compound, bromide or iodide can be used in addition to the above chloride.

In the case of using particularly preferred activated carbon as the solid particles for adsorbing the coloring substance in the present invention, the solid particle-containing layer may be further combined with other solid particles, preferably zinc oxide, zinc hydroxide or titanium dioxide. More
The storage desensitization of the photothermographic material is improved.

Any photosensitive silver halide may be used in the photothermographic material of the present invention, but the silver iodide content is preferably 2 mol% or less, particularly preferably 1 mol% or less. Are silver chloride, silver bromide, silver chlorobromide and silver chloroiodobromide. More preferably, silver bromide or silver chlorobromide or silver bromide having a silver bromide content of 80 mol% or more is a latitude which satisfies the performance of both desorption of sensitizing dye and development inhibition of halogen ions. It is preferable because of its large size.

The grain size of the above silver chlorobromide emulsion is generally 0.05.
˜1 μm, preferably 0.1 to 0.5 μm. Particularly, silver halide spectrally sensitized with a sensitizing dye is preferably 0.1 to 0.4 μm.
If it is m, the effect of the present invention is great. The crystal habit of the photosensitive silver halide may be any one such as octahedron, cubic crystal and tetradecahedron. However, when a cubic silver halide emulsion is used, the water-soluble halide of the present invention is preferably used. The silver emulsion has a great effect of preventing desensitization during storage.

The silver halide may be a silver halide grain having a uniform composition from the inside to the surface of the grain, or a silver halide grain having a composition changing continuously or stepwise inside and on the surface.

Further, for example, US Pat. Nos. 2,592,250 and 3,2,2
20,613, 3,271,257, 3,317,322, 3,511,62
No. 2, No. 3,531,291, No. 3,447,927, No. 3,761,266,
The internal latent image type silver halide emulsions described in JP-A-3,703,584, JP-A-3736,140, JP-A-3,761,276, JP-A-52-15661 and JP-A-55-127549 can also be used.

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

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 below, and a part of the organic silver salt is subjected to photosensitive halogenation. It can also be formed by converting a part of silver.

The photosensitive silver halide emulsion is prepared by chemically sensitizing the surface of silver halide grains with a known sensitizer (eg, active gelatin, inorganic sulfur, sodium thiosulfate, thiourea dioxide, sodium chloroaurate). It is also possible to carry out chemical sensitization in the presence of a nitrogen-containing heterocyclic compound or a mercapto group-containing heterocyclic compound.

Further, the light-sensitive silver halide can be spectrally sensitized to blue, green, red and near-infrared light by a known spectral sensitizing dye such as cyanine and merocyanine which is 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.
Can be added at any time during the formation of silver halide grains, the removal of soluble salts, before the start of chemical sensitization, at the time of chemical sensitization, or after the end of chemical sensitization.

A known organic silver salt can be used in the photothermographic material of the present invention for the purpose of increasing sensitivity and improving developability.

The organic silver salt that can be used in the present invention is
For example, JP-B-43-4921, JP-A-49-52626, and JP-A-52-14
1222, 53-36224, 53-37626, 53-36224,
53-37610 and other publications and U.S. Patent 3,330,633,
No. 3,794,496, No. 4,105,451, etc., silver salts of long-chain aliphatic carboxylic acids and silver salts of carboxylic acids having a heterocycle (for example, silver behenate, α- (1-phenyltetrazolethio)). Silver acetate), Japanese Patent Publication No. 44-26582, No. 45-
No. 12700, No. 45-18416, No. 45-22815, JP-A-52-1373
No. 21, No. 58-118638, No. 58-118639, U.S. Pat.
Examples thereof include silver salts of compounds having an imino group described in JP-A No. 274 and the like, acetylene silver described in JP-A No. 61-249044, and the like.

Particularly, a silver salt of a compound having an imino group is preferable, and for example, a silver salt of benzotriazole and its derivative (for example, silver benzotriazole, silver 5-methylbenzotriazole, etc.) is particularly preferable.

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

Examples of dye-donor substances include JP-A-61-6
No. 1157, No. 61-61158, No. 62-44738, No. 62-129850
No. 62, No. 62-129851, No. 62-129852, No. 62-169158,
A coupler forming a diffusible dye described in Japanese Patent Application No. 1-200859, for example, a leuco dye described in JP-A-61-88254, an azo dye described in U.S. Pat.No. 4,235,957, or a U.S. Pat. , 4,439,513, JP-A-59-60434,
59-65839, 59-71046, 59-87450, 59-123
837, 59-124329, 59-165054, 59-165055 and the like. A compound that forms a diffusible dye by a coupling reaction is particularly preferable.
This is represented by the general formula (a) in the lower left column, second line, page 9 of the publication.

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 lower right column, line 8 of the same publication, is preferable.

Examples of positive type dye-donor substances include:
JP 59-55430, 59-165054, 59-154445,
59-116655, 59-124327, 59-152440, 64-13
There are compounds described in each publication such as No. 546.

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,
A dye-donor substance is contained in a microcapsule together with the polymerizable compound described in JP-A-2-293753 and JP-A-2-308162, and the resulting compound is thermally developed to image-wise the polymerization reaction of the polymerizable compound. Alternatively, it can also be applied to a photothermographic material of a type in which the microcapsules are cured in the reverse image to change the diffusivity of the dye-donor substance to the image receiving layer to form an image.

The photothermographic material of the invention may contain a known mercapto compound as an antifoggant or a development accelerator. Whether the mercapto-based compound functions as an antifoggant or a development accelerator depends on the method of heat development, but desorption of the sensitizing dye by the adsorbing solid particles causes such a mercapto compound to exist. In that case, it is likely to be promoted, and if sufficient water-soluble halide is added to completely prevent this, the sensitivity is lowered,
Alternatively, the developability is likely to be significantly reduced.

However, the desorption of the sensitizing dye by such a mercapto compound is small when the compound having a mercapto group having a water-soluble group is used, and the effect of the present invention by the water-soluble halide of the present invention is maximized. Can be demonstrated to.

The mercapto compound having a water-soluble group preferably used in the present invention is a mercapto compound having at least one amino group, carboxyl group, sulfo group, hydroxyl group, sulfinic acid group, and phosphorous acid group, For example, the following compounds can be mentioned.

[0059]

[Chemical 4]

In addition to the above, for example, JP-A-63-153539
, (A-1) to (A-10) and (A-
13), (A-16), (A-19), (A-21), (A-22), (A-34) ~
(A-37), (A-40), (A-41), and (1) to (24) described on pages 3 to 5 of JP-A No. 3-7113.

These mercapto compounds having a water-soluble group are used in an amount of 0.1 mol based on 1 mol of the total photosensitive silver halide emulsion.
~ 50 mmol can be used, but preferably 0.5
Used in the range of ~ 20 mmol. The reducing agent used in the photothermographic material of the present invention is selected from those conventionally known for photothermographic materials depending on the developing mechanism and the dye formation or release mechanism. The reducing agent referred to herein also 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 US Pat. Nos. 3,351,286 and 3,761,270,
3,764,328, 3,342,599, 3,719,492, Research Disclosure 12,146, 15,108
No. 15,127, and JP-A-56-27132, 53-135628.
No. 57-79035 p-phenylenediamine-based and, and p- aminophenol-based developing agent, phosphoric acid amide phenol-based developing agent, sulfonamide aniline-based developing agent, and hydrazone-based developing agent, phenols, sulfone Amidophenols, polyhydroxybenzenes,
There are naphthols, hydroxybisnaphthyls, methylenebisphenols, ascorbic acids, 1-aryl-3-pyrazolidones, hydrazones, and precursors of the above various reducing agents.

The dye-providing substance can also serve as the reducing agent.

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

Examples of the thermal solvent which can be used in the present invention include US Pat. Nos. 3,347,675, 3,667,959 and 3,347,675.
438,776, 3,666,477, Research Disclosure No. 17,643, JP-A-51-19525, 53-24829, 5
3-60223, 58-118640, 58-198038, 59-2295
No. 56, No. 59-68730, No. 59-84236, No. 60-191251,
No. 60-232547, No. 60-14241, No. 61-52643, No. 62-78
No. 554, No. 62-42153, No. 62-44737.
No. 63-53548, No. 63-161446, JP-A 1-224751
No. 2-863, No. 2-120739, No. 2-123354, and the like. Specifically, urea derivatives (urea, dimethylurea, phenylurea, etc.), amide derivatives (eg acetamide, stearylamide, p-
Toluamide, p-propanoyloxyethoxybenzamide etc.), sulfonamide derivative (eg p-toluenesulfonamide etc.) and polyhydric alcohols (eg 1,6 hexanediol, pentaerythritol, polyethylene glycol etc.) are preferably used.

The above thermal solvent can be added to any layer such as a light-sensitive silver halide emulsion layer, an intermediate layer, a protective layer, or an image receiving layer of an image receiving material. Wt% to 500 wt%, more preferably 20 wt% to 2
It is 00% by weight.

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

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

Examples of the development accelerator include, for example, JP-A-59-177.
550, 59-111636, 59-124333, 61-72233
No. 61-236548, JP-A 1-152454, JP-A 61-1596.
No. 42, JP-A-1-104645 and Japanese Patent Application No. 1-110767, or a development accelerator releasing compound, or a metal ion having an electronegativity of 4 or more described in JP-A-1-104645 can also be used. ..

Examples of the antifoggant include US Pat.
645,739, higher fatty acids, secondary mercury salts described in JP-B-47-11113, N-halides described in JP-A-51-47419, US Pat. No. 3,700,457, JP-A-51- Fifty
No. 725, Japanese Patent Application No. 1-69994, mercapto compound-releasing compounds described in 1-104271; arylsulfonic acid described in JP-A-49-125016; lithium carboxylate described in 51-47419; British Patent 1,455,271 and oxidizers described in JP-A-50-101019, sulfinic acids and thiosulfonic acids described in 53-19825, thiouracils described in 51-3223, sulfur described in 51-26019, sulfur, No. 51-42529, No. 51-811
No. 24, and No. 55-93149, disulfides and polysulfides, No. 51-57435, rosins or diterpenes, No. 51-104338, polymer acids having a carboxyl group or a sulfonic acid group, U.S. Pat. Thiazolythion described in 4,138,265, JP-A-54-51821 and JP-A-55-142,331.
No. 3, U.S. Pat. No. 4,137,079, triazoles, JP-A-55-140883, thiosulfinic acid esters, JP-A-59-46641, 59-57233, and 59-57234.
-Or tri-halide, a thiol compound described in JP-A-59-111636, a hydroquinone derivative described in JP-A-60-198540 and 60-227255, and a hydrophilic group described in JP-A-62-78554 Antifoggants, polymer antifoggants described in JP-A No. 62-121452, anti-foggants having a ballast group described in JP-A No. 62-123456, and colorless couplers described in JP-A No. 1-161239. Be done.

Various known photographic additives other than those mentioned above can be used in the photothermographic material of the present invention. Examples thereof include antihalation dyes, antiirradiation dyes, colloidal silver, optical brighteners, 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 background color tone adjusting agent and the like can be contained. For example, RD (Research
Disclosure) Nos. 17029, No. 29963, JP-A Nos. 62-135825, and 64-13546.

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, the supports 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 having a white pigment on a paper substrate such as cast coated paper or baryta paper is used.

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

The image-receiving layer is roughly classified into a case where the binder itself constituting the image-receiving layer has a dye-receiving ability and a case where a mordant capable of receiving the dye is contained in the binder. When the binder has a dye-accepting ability, the substance preferably used has a glass transition temperature of about 40 ° C. or higher and about 250.
Those formed of a polymer having a temperature of ℃ or less are preferable, and specifically, "Polymer Handbook Second Edition" (edited by Joy Brand Wrap, EH Inmargat), John Willie & Sons Publishing {Polymer Handbook 2nd.ed. (J. Brandrup, EHI
mmergut ed) John Wily & Sons} synthetic polymers having a glass transition temperature of about 40 ° C. or higher are useful,
Generally, the molecular weight of the polymer is 2,000 to 200,000.
Something is useful. These polymers may be used alone or in combination of two or more kinds, and may be a copolymerizable polymer having two or more kinds of repeating units.

Specifically, JP-A-2-863, page 14, upper left column 1
The polymers described from the 4th line to the 14th line in the upper right column can be used including the preferable polymers.

Further, in the image receiving material in which the image receiving layer contains a mordant in the binder, a polymer containing a tertiary amine or a quaternary ammonium salt is preferably used as the mordant. For example, US Pat. 64-64
Examples thereof include compounds described in Japanese Patent No. 13546. As the binder used for holding these mordants, hydrophilic binders such as gelatin and polyvinyl alcohol are preferably used.

A dye receiving layer obtained by dispersing a hydrophobic polymer latex having dye receiving ability in a hydrophilic binder in a form similar to 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, in which case all of them are dyes. It can be an image receiving layer, or only a part of the constituent layers can be an image receiving layer.

When the image-receiving material has a support separately from the image-receiving layer, the support for the image-receiving material may be either a transparent support or a reflective support. The support described in column 15 line to lower right column 8 line,
It can be selected from the reflective supports having the second type diffuse reflectance and used.

Various known additives can be added to the image-receiving material of the present invention. Examples of such additives include stain inhibitors, ultraviolet absorbers, optical brighteners, image stabilizers, development accelerators, antifoggants, pH regulators (acid and acid precursors, base precursors, etc.), heat Solvents, organic fluorine compounds, oil droplets, surfactants, hardeners, matting agents, various metal ions and the like can be mentioned.

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 which can be used, those described in JP-A-2-863, page 12, lower left column, lines 13 to 16 can be used, preferably a laser light source, CR
T light source and LED are used. Also, a light source in which a semiconductor laser and an SHG element (second harmonic generation element) are combined can be used.

The photothermographic material of the present invention is preferably 70 to 200 ° C., more preferably 90 to 170 ° C., preferably 1 to 180 seconds, more preferably 2 to 2 after or at the same time as imagewise exposure. It is heat-developed for 120 seconds to form a dye image. The transfer of the diffusible dye to the image-receiving material may be performed simultaneously with the heat-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 the heat-development. The dye may be transferred by bringing it into close contact with the material, and further, after supplying water, the photosensitive material and the image receiving material may be brought into close contact with each other. In addition, the photosensitive material is preheated in the range of 70 to 160 ° C. before exposure, or disclosed in JP-A-60-143338 and 61-16-16.
As described in No. 2041, immediately before development, at least one of the light-sensitive material and the image-receiving material can be preheated in the temperature range of 80 to 120 ° C.

When the heat-developable photosensitive 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 The described method, the method by far infrared heating, etc. can be used.

The heating pattern at the time of heat development is not particularly limited, and it may be carried out at a constant temperature, at a high temperature in the initial stage of development and at a low temperature in the latter half of development, or vice versa.
Further, any method such as a method of changing the temperature region in three or more steps or a method of continuously changing the temperature can be used.

[0087]

EXAMPLES Examples of the present invention will be shown below, but the embodiments of the present invention are not limited thereto.

Example 1 [Preparation of Photothermographic Material] A photothermographic material 1 having the layer constitution shown below was prepared on a photographic baryter paper having a thickness of 160 μm.

Here, the addition amount of each material is shown by the amount per 1 m ^{2 of the} photothermographic material.

The photosensitive silver halide emulsion and the organic silver salt are each expressed in terms of silver. (The amount of all the following additives used is also the same.) (Layer structure of the photothermographic material 1) Subbing layer Polyphenylene ether 2.0 g Polystyrene 2.0 g Antifoggant-2 1.0 g First layer (red photosensitive layer) Benzo Triazole silver 0.8g Tricresyl phosphate (TCP) 0.03g Dye donor (3) 1.2g Red-sensitive silver halide emulsion 0.68g (Ag) Gelatin 1.3g Polyvinylpyrrolidone (K-30) 0.6g Thermal solvent-A 4.5g Sodium chloride 0.001g Potassium bromide 0.003g Anti-irradiation dye-2 0.01g FR-1 0.005g Scavenger A 0.1g 2nd layer (1st intermediate layer) Gelatin 0.8g Reducing agent 1.12g TCP 0.2g 3rd layer (green) Photosensitive layer) Benzotriazole silver 0.24g TCP 0.2g Dye-donor (2) 0.9g Green-sensitive silver halide emulsion 0.31g
(Ag) Gelatin 2.0g PVP (K-30) 0.1g Hot solvent-A 3.45g Anti-irradiation dye 0.02g FR-1 0.008g Scavenger A 0.08g 4th layer (2nd intermediate layer) Gelatin 1.55g Reducing agent 1.2 g UV absorber-1 0.3g TCP 0.22g Yellow filter dye 0.26g Fifth layer (blue photosensitive layer) benzotriazole silver 0.7g TCP 0.344g Dye-donor (1) 1.2g Blue-sensitive silver halide emulsion 0.25g (Ag ) Gelatin 1.2g PVP (K-30) 0.4g Hot solvent-A 4.0g FR-1 0.002g Scavenger A 0.1g 6th layer (protective layer) Gelatin 0.7g Polyvinylpyrrolidone (K-30) 0.2g ZnSO ₄ 0.65g Reducing agent 0.34g TCP 0.2g DAP 0.1g UV absorber-1 0.4g Each addition amount represents the amount added per 1 m ² . For each layer,
It contains 0.03 g of bisvinylsulfonylmethyl ether per 1 g of gelatin as a hardening agent and also contains a surfactant (S-4) necessary for coating. The reducing agent is a 7: 3 (weight ratio) mixture of reducing agent-1 and reducing agent-2.

The structural formulas of the additives used in the photosensitive layer of the photothermographic material are shown below.

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[Chemical 5]

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[Chemical 6]

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[Chemical 7]

[Benzotriazole silver emulsion] Prepared by simultaneous mixing of an aqueous solution of ammoniacal silver nitrate and benzotriazole (containing 0.2 mol of ammonia water with respect to benzotriazole) in a 10% aqueous solution of phenylcarbamoyl gelatin at 50 ° C., and the addition was completed. Needle-like crystals (width 0.1-0.2μm, length 0.5-2μ)
m) got.

To this, 20 mg of ST-2 as a stabilizer was added per mol of benzotriazole silver. The photosensitive silver halide emulsion (AgBrCl) used is shown in the table below.

Item Blue Photosensitive Green Photosensitive (GEM-1) Red Photosensitive Halogen composition (Br mol%) 70 60 70 Particle shape Hexagonal cubic Cubic average particle size * 1 0.30 μm 0.19 μm 0.20 μm Particle size Distribution coefficient * 2 0.15 0.17 0.13 Surface chemical sensitization method * 3 S + Au S S + Au Stabilizer ST-1 ST-1 ST-2 Sensitizing dye BSD-1 GSD-1 RSD-1 * 1 Diameter in sphere conversion * 2 grains Diameter distribution coefficient = (particle size distribution standard deviation) / (average particle size) * 3 S + Au: gold-sulfur sensitization with sodium thiosulfate and potassium chloroaurate S: sulfur sensitization with sodium thiosulfate To each silver emulsion, 10 ^-6 mol of sodium iridium (IV) chloride was added per 1 mol of silver halide during grain formation.

ST-1: 5-methyl-1,3,3a, 7-tetrazaindene Each chemical sensitization was carried out in the presence of a sensitizing dye.

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[Chemical 8]

Next, in the photothermographic material-1, the layer-
2, activated carbon that adsorbs the coloring substances shown in Table 1 is added,
Photothermographic materials-2 to 18 were prepared.

Activated carbon was used in an aqueous solution per 1 g of activated carbon.
0.02 g of the exemplified surfactant (S-7) was added, and wet pulverization was performed for 20 hours by a sand mill disperser using 0.5 mm glass beads to obtain an activated carbon fine particle dispersion A having an average particle size of about 0.45 μm. .. The film surface pH of the photosensitive layer is the second layer and the fourth layer, respectively.
The pH values of the coating solutions for the first layer and the sixth layer were changed.

The obtained photothermographic material was heated at 40 ° C. and 65% RH.
It was stored for 48 days and hardened to a desired degree of dura. (Water absorption = 210% ± 40%) The film surface pH of the photosensitive layer of each of the obtained photothermographic materials was measured with a pH meter (HM-30S) manufactured by Toa Denpa Kogyo Co., Ltd. and a flat surface p.
The film surface pH of the photosensitive layer was measured using a combination of H electrodes (GST-5213F). Measurement is 25 ℃ in a room air-conditioned at 25 ℃ and 80% RH.
10 .mu.l of distilled water (conductivity at 25.degree. C. = 0.29 .mu.s / cm) was dripped onto the surface of the photosensitive layer with a microsyringe, the flat electrode was immediately pressed, and a stable pH was measured after about 30 seconds.

The results obtained are shown in Table 1.

[Preparation of Image Receiving Agent Material] An image receiving material was prepared by coating an image receiving layer having the following composition on the same photographic variator support as that used for producing the photothermographic material.

(The addition amount is the amount per 1 m ² of the image receiving material.) Polyvinyl chloride (average degree of polymerization: 500) 10 g Image stabilizer-1 1.1 g Image stabilizer-2 0.3 g Image stabilizer-3 0.5 g Image Stabilizer-4 0.5g Image stabilizer-5 0.3g Thermal solvent-B 4.2g

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[Chemical 9]

[Evaluation of Photothermographic Material] Each of the obtained photothermographic materials was subjected to imagewise exposure after being stored at 50 ° C. and relative humidity of 60% for 3 days and after not being stored. A heat development treatment was carried out at 150 ° C. for 60 seconds.

Then, the photothermographic material was superposed on the image receiving material-1 and superposed at 120 ° C. for 20 seconds to perform dye transfer. Sensitometry was performed on the magenta dye image of the obtained dye image to determine Dmax, Dmin and sensitivity. The results are shown in Table 1.

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[Table 1]

From the results shown in Table 1, the addition of activated carbon reduces the stain (blue reflection density) in the white background at the time of thermal development, but when the photothermographic material is stored, the surface pH of the photosensitive layer is reduced. Those having a pH of 5.5 to 8 within the scope of the present invention are
There is little desensitization on storage, but a photothermographic material having a photosensitive layer having a pH of less than 5.5 has a large desensitization on storage. Also,
The photothermographic material having a photosensitive layer surface pH of more than 8 is
It can be seen that the value of the minimum concentration (Dmin) becomes extremely high, and the effect of adding activated carbon cannot be obtained at all. It can be seen that the photosensitive layer having a film surface pH of 6 to 7.5 is most preferable.

Example-2 Photothermographic material in the same manner as in Example 1 except that the activated carbon dispersion A used in the photothermographic material-9 prepared in Example-1 was changed to the following B to G. Create 21-26,
It evaluated similarly to Example-1. Materials-21 to 25 were prepared and evaluated in the same manner as in Example-1.

Except for activated carbon dispersion B S-7, 0.001 g of C S-7 was added per 1 g of activated carbon, D S-7 was added at 0.008 g per 1 g of activated carbon, E S-7 was added at 0.08 g per 1 g of activated carbon F 0.002 g of green sensitizing dye GSD-1 was added per 1 g of activated carbon = 0.002 g of green sensitizing dye GSD-1 was added per 1 g of activated carbon in G dispersion C. The results are shown in Table 2.

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[Table 2]

From the results shown in Table 2, when the activator was added to the activated carbon fine particles, the addition amount was 0.01 to 10 relative to the activated carbon.
It can be seen that the one having a weight% shows a particularly favorable storage stability while maintaining a particularly good Dmin.

Further, it can be seen that the addition of the sensitizing dye more effectively suppresses the desensitization due to the adsorbed solid particles.

Example-3 In the photothermographic material-9 prepared in Example-1, solid particles shown in Table 3 were further added to the second layer containing activated carbon (zinc oxide having an average particle size of 0.3 μm, average particle size: 0.3 μm). Photothermographic materials 31 to 38 containing 0.42 μm zinc hydroxide) were prepared and evaluated in the same manner as in Example-1. The results are shown in Table 3.

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[Table 3]

From the results shown in Table 3, the effect of the present invention by combining solid particles with activated carbon, that is, the storage desensitizing effect of activated carbon, can be more remarkably reduced by controlling the film surface pH to a specific value. It turns out that

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According to the present invention, it is possible to provide a photothermographic material containing solid particles capable of effectively adsorbing a coloring substance produced at the time of heat development and which does not deteriorate the storage performance of the photothermographic material.

Claims (1)

[Claims] 1. A support comprising at least a hydrophilic binder, a photosensitive silver halide, a dye-donor substance that releases or forms a diffusible dye during heat development, and solid particles that adsorb a coloring substance generated during heat development. In the photothermographic material containing the photothermographic material, the film surface pH on the photosensitive layer side of the photothermographic material is 25
A photothermographic material having a temperature of 5.5 to 8 at ° C.