JPH01167744A - Heat developable photosensitive element - Google Patents

Abstract

PURPOSE:To provide an image which is less fogged at the time of heat development with a high sensitivity by chemically sensitizing the title element in such a manner that the latent image distribution of at least half of a silver halide emulsion has one maximal value in the particle and the position of such value is the depth of a prescribed value or below from the surface and the particle surface has the latent image as well. CONSTITUTION:This element has at least the silver halide emulsion and binder on a base. The silver halide emulsion is chemically sensitized in this case in such a manner that at least >=50% thereof has at least one maximal value within the particle in the latent image distribution after exposing and the position (mode) where this maximal value is <0.02mum from the surface and even the particle surface has the latent image. The sufficient effect of color sensitization of the internal latent image type emulsion is obtd. and the sufficient development and substantial sensitivity are obtd. in a practicable heat development processing only when the mode of the latent image distribution is <0.02mum and the particle surface has the latent image. The image which is less fogged at the time of the heat development is thereby obtd. with the high sensitivity.

Description

[Detailed description of the invention] ■Background of the invention Technical field The present invention relates to thermally developable photosensitive elements.

Prior art and its problems Photography using silver halide has traditionally been the most widely used method, as it has superior photographic properties such as sensitivity and gradation control compared to other photographic methods, such as electrophotography and diazo photography. It is used in

In recent years, a technology has been developed that allows images to be easily and quickly obtained by changing the image forming method for photosensitive elements using silver halide from the conventional wet processing using a developing solution to a dry processing using heating, etc. has been done.

Heat-developable photosensitive elements applied to such processing methods are well known in this technical field, and many methods have been proposed for obtaining color images. The law is JP 57-179840, JP 57-186774, JP 57-198458,
No. 57-207250, No. 58-58543, No. 5
No. 8-79247, No. 58-116537, No. 58-
No. 149046, No. 59-48764, No. 59-65
No. 839, No. 59-71046, No. 59-87450
No. 59-88730, etc.

When photosensitive silver halides and/or organic silver salts are reduced to silver by thermal development, they form or release mobile (diffusible) dyes in response to or inversely to this reaction, and this mobile (diffusible) dye is formed or released. This is a method in which a dye is transferred to a dye-fixing element.

Various types of silver halide emulsions are known for use in photosensitive elements in such thermal development image forming methods.

Incidentally, in an image forming method using a silver halide photosensitive element, it is necessary to improve the light absorption, quantum efficiency, and developability of the silver halide emulsion in order to satisfy both the sensitivity of the photosensitive element and the requirements for image quality.

For these reasons, the use of internal latent image type silver halide emulsions as silver halide emulsions has attracted attention in recent years.

Examples of such internal latent image type silver halide emulsions include those disclosed in US Pat. No. 3,979,213 (hereinafter referred to as Document A). This emulsion has significantly smaller inherent desensitization during color sensitization than silver halide emulsions of equal grain size that are chemically sensitized only on the surface, and as a result, it is possible to effectively use a large amount of sensitizing dye. It is possible to carry out color sensitization. However, the internal latent image type emulsion used here has most of the radiation-sensitive areas (or latent image forming areas) inside the grains, and the ratio of surface sensitivity to total sensitivity is 10% or less. An emulsion that forms a latent image sufficiently inside the grains will be insufficiently developed even when thermally developed, resulting in a substantial loss of sensitivity. Moreover, if a large amount of sensitizing dye as disclosed herein is adsorbed onto silver halide grains, development of the grains will be further inhibited, which is undesirable.

Similarly, Journal of Photographic Science Vol. 13, p. 48 (1965), Vol. 22, p. 174 (1965)
1974), Vol. 25, p. 19 (1977), Vol. 31
Vol. 41 (1986), Photographic Science and Engineering, Vol. 19, p. 333 (1)
975), U.S. Patent No. 4,035°185, U.S. Patent No. 3
, No. 850, 637, Berichte der Bunsen Gesellschaft Fair Physiikarische Chemie-16.
In internal latent image type emulsions such as those described in Vol. 7, p. 356 (1963), the largest number of radiation-sensitive areas is 0.
．． This is a deep position of 0.01 μm or more, and cannot be easily developed by heat development, so that optimum sensitivity and S/N ratio cannot be achieved.

Further, U.S. Pat. No. 3,966,476 discloses an emulsion in which the latent image is located in cavities that open toward the grain surface and is developable with a surface developer. However, an emulsion that can develop a sensitivity equal to or higher than that of a surface latent image type emulsion of the same size by processing with a surface developer cannot be called an internal latent image type emulsion, and the advantages of an internal latent image type emulsion described in Reference A However, color sensitization cannot be fully utilized.

Regarding the manufacturing method of silver halide emulsions with high internal sensitivity,
U.S. Pat. No. 3,206,313 discloses that chemically sensitized large grains are mixed with unchemically sensitized fine grain emulsions and subjected to Ostwald ripening. , No. 485 describes that silver ions and halide ions are added alternately in excess to chemically sensitized particles. By controlling the thickness of the shell using such a preparation method, it is possible to appropriately adjust the balance between surface sensitivity and internal sensitivity.

However, it is not clear what the depth at which the most latent images are formed is, and what is the distribution of latent images from the surface to the inside for the processing solutions and thermal development methods used in practical use. It is not clear whether this is preferable for achieving good sensitivity and image quality.

Under these circumstances, the applicant filed a patent application in 1982-127.
No. 391 states that in a conventional silver halide emulsion subjected to wet development, the latent image distribution has at least one maximum value inside the grains, and the position of this maximum value is located at a depth of about 0.01 μm from the surface. , and also has a number of latent images on the particle surface.

This material has sufficient sensitivity to the processing liquid used in practical use.

Incidentally, in heat-developable photosensitive elements, known auxiliary developing agents such as hydroquinones, hydroxyamines, pyrazolidones, etc., which have the effect of promoting development by mediating the reaction between silver halide and the developing agent, are used.

However, many of these auxiliary developers still cannot be said to have a sufficient development accelerating effect, and even if they do have a development accelerating effect, there are problems such as an increase in fog.

On the other hand, in thermal development, fogging that cannot be predicted from normal wet development (processing in a developer) often occurs.

This fog results in an increase in the minimum density for negative-working photosensitive elements that form color images in correspondence with the latent image, and a decrease in the maximum density for positive-working photosensitive elements that form color images in inverse correspondence with the latent image. . Various anti-fog techniques have been proposed to suppress this fog.

For example, US Pat. No. 3,589,903 describes that mercury compounds are effective in suppressing fog during thermal development, but it is undesirable to use such compounds that are harmful to the human body.

In addition, JP-A-60-198540 describes specific hydroquinone derivatives and 2,4-disulfonamidophenol derivatives, but these compounds cannot be said to have sufficient anti-fogging effects, and are highly sensitive to halogenated compounds. It has drawbacks such as causing desensitization to silver emulsions.

In fact, in the conventional so-called surface latent image type emulsions described above, even if an antifoggant is used, the antifogging effect is insufficient, and the development suppressing effect is large, making it impossible to obtain high sensitivity.

However, it has been found that the emulsion proposed in the above-mentioned Japanese Patent Application No. 127391/1980, which has a latent image mainly inside shallow grains, has less fog during thermal development and can provide high sensitivity.

! ! OBJECTS OF THE INVENTION An object of the present invention is to provide a heat-developable photosensitive element that can provide images with high sensitivity and less fog during heat development.

III Disclosure of the invention Such objects are achieved by the invention described below.

That is, the present invention provides a heat-developable photosensitive element having at least a silver halide emulsion and a binder on a support, in which at least 50% of the silver halide emulsion has at least one maximum value inside the grains in its latent image distribution. The position of this maximum value is 0.02μ from the surface.
This is a heat-developable photosensitive element characterized by being chemically sensitized so that the particle surface has a latent image at a depth of less than m.

■Specific structure of the invention Hereinafter, a specific configuration of the present invention will be explained in detail.

The heat-developable photosensitive element of the present invention has at least a silver halide emulsion and a binder on a support. in this case,
At least 50% or more, preferably 70% or more of the silver halide emulsion has at least one maximum value inside the grains in the latent image distribution after exposure, and the position where this maximum value exists ( mode) is 0.02 μm from the surface
The particle surface has a depth of less than 0.015 μm, preferably 0.015 μm or less, and has been chemically sensitized so that the particle surface also has a latent image. The number of latent images on the particle surface is preferably 175 or more and less than 1 times the maximum value.

Here, the latent image distribution is defined as the depth of the latent image from the particle surface (
X μm), the number of latent images (y) is plotted on the vertical axis, where X is S: silver halide emulsion average grain size (μm), Ag1: residual silver after performing the following treatment on an unexposed emulsion coated sample. Amount AgO: is the amount of coated silver before processing, and y is after white exposure for 1/100 seconds,
It is the reciprocal of the exposure amount that gives a density of fog +0.2 when the following processing is performed. The processing conditions for obtaining the above latent image distribution are: N-methyl-p-aminophenol sulfate 2.58 L-sodium ascorbate 10 g Sodium metashelate
35g potassium bromide 1
Add 0 to 10 g/l of anhydrous sodium sulfite to the treated solution (pH 9.6) by adding g water.
The treatment is carried out at 5°C for 5 minutes. Here, the amount of anhydrous sodium sulfite is O~10g/J! By changing the number of latent images in the silver halide grains during processing, the depth from the surface of the latent image in the silver halide grains developed during processing changes, and it is possible to know the change in the number of latent images in the depth direction.

If the maximum value of the latent image distribution determined in this manner exists at a position deeper than 0.02 μm from the surface, development will be insufficient and the sensitivity will be substantially impaired.

Only when the latent image distribution mode is less than 0.02 μm and a latent image is present on the grain surface, the color sensitizing effect of the internal latent image type emulsion is sufficient, and development in practical thermal development processing is sufficient. Therefore, substantial sensitivity can be obtained.

This effect especially increases the number of latent images on the particle surface to a maximum value of 11.
It increases by setting it to 5 or more and less than 1 times.

Silver halides that can be used in the present invention include silver chloride, silver bromide,
Any of silver iodobromide, silver chlorobromide, silver chloroiodide, and silver chloroiodobromide may be used.

The silver halide composition in the present invention is not particularly limited, but silver chloride is 50 mol% or less, and silver iodide is 10 mol%.
The following silver bromide, silver iodobromide, silver chlorobromide, and silver chloroiodobromide are preferred.

The silver halide grains in the present invention are cubic, octahedral,
So-called regular particles having regular crystal bodies such as tetradecahedrons may also be used.

Further, it may have an irregular crystal shape such as a tabular shape or a spherical shape, a crystal defect such as a twin plane, or a composite shape thereof. Among these, regular particles are preferred in terms of controlling the latent image distribution. Also, mixtures of various crystal forms may be used.

Tabular grains having an aspect ratio of 5 or more are also preferably used in the present invention.

The grain diameter of the silver halide may be fine grains of about 0.1 μm or less, or dog-sized grains with a projected area diameter of about 10 μm. Further, it may be a monodisperse emulsion with a narrow distribution or a monodisperse emulsion with a wide distribution. Among these, monodispersed emulsions are preferred in terms of improving graininess.

Monodispersed emulsions are typically those in which at least 95% by weight of the emulsions are within ±40% of the average grain diameter. The present invention uses an emulsion in which the average grain diameter is 0.05 to 3 μm, and at least 95% by weight or (number of grains) of silver halide grains are within the range of ±20% of the average grain diameter. can.

A method for making such an emulsion is described in U.S. Pat. No. 3,574.6.
No. 28, No. 3,655,394 and British Patent No. 1
, No. 413.748. Also, Tokukai Sho 4
No. 8-8600, No. 51-39027, No. 51-83
No. 097, No. 53-137133, No. 54-4852
No. 1, No. 54-99419, No. 5B-37635,
Monodisperse emulsions such as those described in Japanese Patent No. 58-49938 can also be preferably used in the present invention.

The silver halide emulsion comprising regular grains used in the present invention can be obtained by controlling PAg and pH during grain formation. For more information, see
Science and Engineering (Photog
rapicScience and Engineering
ring) Volume 6, pp. 159-165 (1962),
Journal of Photographic ΦScience (J
our own of Photographic 5ci
ence) Volume 12, pages 242-251 (1964)
, U.S. Patent No. 3,655.394 and British Patent No. 1
, No. 413,748.

Tabular grains are described by Gutoff, Photographic Science and Engineering.
tographic 5science and Eng
ineer-ing) Volume 14, pp. 248-257 (1
970); U.S. Patent No. 4,434,226;
No. 414,310, No. 4,433,048, No. 4,4
39,520 and British Patent No. 2.112,157.

When tabular grains are used, there are advantages such as increased covering power and increased color sensitization efficiency with sensitizing dyes.
It is described in detail in US Pat. No. 4,434,226, cited above.

The structure and manufacturing method of monodisperse hexagonal tabular grains as one type of tabular grains are described in Japanese Patent Application No. 61-299155. Briefly, such an emulsion is a silver halide emulsion containing a dispersion medium and silver halide grains, in which 70% or more of the total projected area of the silver halide grains has a minimum length. It is a hexagonal shape in which the ratio of the length of the longest side to the length of the side is 2 or less, and is occupied by tabular silver halide having two parallel surfaces as outer surfaces, and , the coefficient of variation of the grain size distribution of these hexagonal tabular silver halide grains (the variation in grain size expressed by the circular diameter of its projected area)
It has a monodispersity of 20% or less (standard deviation) divided by the average particle size), and an aspect ratio of 2.
5 or more and the particle size is 0.2 μm or more.

The hexagonal tabular grains may have a composition of silver bromide, silver iodobromide, or silver chloroiodobromide. If it contains a demon ion, its content is 0 to 30 mol%, and the crystal structure may be --like, the inside and outside may have different halogen compositions, or it may have a layered structure. .

Further, the concentration distribution may be provided for the entire layer or for each layer.

These silver halide grains can be produced through nucleation, Ostwald ripening and grain growth, the details of which are as described in Japanese Patent Application No. 61-299155.

The monodisperse hexagonal tabular grains can be sheathed into core-sheath emulsions by techniques well known in the art. The method for forming this silver salt sheath is described in U.S. Patent No. 3,367.7.
No. 76, No. 3,206,313, No. 3,317,
No. 322, No. 3,917,485, and No. 4.
The description in No. 164,878 can be referred to.

A method for preparing internal latent image emulsions is described in U.S. Patent No. 3.979.
, No. 213, No. 3,966.476, No. 3,206,
No. 313, No. 3,917゜485, Special Publication No. 43-29
405, Japanese Patent Publication No. 45-13259, etc. can be used, but in any method, in order to obtain an emulsion with a latent image distribution according to the present invention,
The method of chemical sensitization, the amount of silver halide to be precipitated after chemical sensitization, and the conditions for precipitation must be adjusted.

Specifically, in U.S. Pat. No. 3,979,213, an internal latent image type emulsion is prepared by a method in which silver halide is again precipitated on emulsion grains whose surfaces have been chemically sensitized by the Chondrald double jet method. . Once silver halide has been precipitated onto the grains in the amounts practiced in this patent, the ratio of surface sensitivity to total sensitivity is 10
It becomes smaller than 1/1. For this reason,
To obtain the latent image distribution of the present invention, the amount of silver halide precipitated after chemical sensitization must be less than that practiced in U.S. Pat. No. 3,979,213.

Further, US Pat. No. 3,966,476 also discloses a method in which silver halide is precipitated above emulsion grains after chemical sensitization by the Chondrald double jet method.
However, if silver halide is precipitated after chemical sensitization by the method practiced in this patent specification, photosensitive nuclei cannot be embedded inside the grains.

Therefore, the emulsion practiced in the above-mentioned patent specification has a lower original surface than an emulsion which has been chemically sensitized even by surface development.
The sensitivity increases by at least 0.021 ogE (E: exposure amount). Therefore, in order to obtain the latent image distribution in the present invention, the amount of silver halide to be precipitated after chemical sensitization must be increased or the precipitation conditions ( For example, it is necessary to control the solubility of silver halide during precipitation and the rate of addition of soluble silver salt and soluble halide.

A silver salt solution (for example, AgNO3 aqueous solution) added to accelerate grain growth during production of tabular grains in the present invention
A method of increasing the addition rate, amount, and concentration of a halide solution (for example, KBr aqueous solution) is preferably used.

These methods are described, for example, in British Patent No. 1.335,
No. 925, U.S. Patent No. 3,672.900, U.S. Patent No. 3,
850,757, 4,242,445, JP-A-55-142329, JP-A-55-158124, etc. can be referred to.

The properties of silver halide grains can be controlled by allowing various compounds to be present during the silver halide precipitation formation process. Such compounds may be initially present in the reactor or may be added along with one or more salts in accordance with conventional methods. U.S. Patent No. 2448.060, U.S. Patent No. 2,628,167, U.S. Patent No. 3
, No. 737, 313, No. 3,772.031, and Research Disclosure, Vol. 134, 1975.
Silver halide precipitation of compounds such as copper, iridium, lead, bismuth, cadmium, zinc (chalcogenic compounds such as sulfur, selenium and tellurium), gold and compounds of Group 8 noble metals as described in June 2013, 13452 The properties of silver halide can be controlled by having it present during the production process.

As described in Japanese Patent Publication No. 58-1410, by Moisar et al., Journal of Photographic Science, Vol. 25, 1977, pp. The inside can be reduced-sensitized.

In addition, known silver halide solvents (for example, ammonia, rhodankali, or Showa 54-100717
Physical ripening can also be carried out in the presence of thioethers and thione compounds (described in No. 2003 or JP-A-54-155828).

Chemical sensitization is described by T. H. James,
The Theory Talent Photographic Process
4th edition, Macmillan Publishing, 1977 (T, H, Jam
es, The Theory of the Phto
graphicProcess, 4th ed, Ma
Cmillan, 1977) pages 67-76.

Also Research Disclosure Volume 120, 197
April 4th, 12008; Research Disclosure, Volume 34, June 1975, 13452, U.S. Patent No. 2,642,361, U.S. Patent No. 3,297°446, U.S. Patent No. 3,772,031, U.S. Patent No. 3,772,031, U.S. Pat. No. 3.857,711;
3,901.714, 4,266.018, and 3,904,415, and pAg5-1 as described in British Patent No. 1°315.755.
0% sulfur at pH 5-8 and temperature 30-80°C,
This can be done using selenium, tellurium, gold, platinum, palladium, iridium or a combination of these sensitizers. Chemical sensitization is optimally performed in the presence of a gold compound and a thiocyanate compound and as described in U.S. Patent No. 3,857,71.
1, 4,266.018 and 4.054
It is carried out in the presence of a sulfur-containing compound such as a sulfur-containing compound or a hypo-, thiourea-based compound, or rhodanine-based compound described in , No. 457. Chemical sensitization can also be carried out in the presence of chemical sensitization aids. The chemical sensitization aid used is a compound known to suppress fog and increase sensitivity during the chemical sensitization process, such as azaindene, azapyridazine, and azapyrimidine. Examples of chemical sensitization aids and modifiers include U.S. Pat. No. 2,131,038.
No. 3,411.914, No. 3,554,75
No. 7, JP-A-58-126526, and the aforementioned "Photographic Emulsion Chemistry" by Duffin, pp. 138-143. In addition to or in place of chemical sensitization, U.S. Pat.
Reduction sensitization can be performed, for example, using hydrogen, as described in U.S. Patent No. 2,518,698;
2,743,182 and 2.743,18
3 using reducing agents such as stannous chloride, thiourea dioxide, polyamines, or low pAg
(eg less than 5) and/or high pH (eg greater than 8) treatment.

Also, U.S. Pat. No. 3,917,485 and U.S. Pat.
Spectral sensitization can also be improved by the chemical sensitization method described in No. 66.476.

Furthermore, the sensitization method using an oxidizing agent described in JP-A-61-3134 and JP-A-61-3136 can also be applied.

In order to remove soluble silver salts from the emulsion before and after physical ripening, the Tardel water washing method, flocculation sedimentation method, ultrafiltration method, etc. are used.

The additives used in the chemical ripening and spectral sensitization of the emulsion used in the present invention are listed in Research Disclosure N.
O, 1 Flo 43 (December 1978) and No. 1
8716 (November 1979).

The sensitizing dyes, antifoggants and stabilizers described below can be present in any step of the photographic emulsion manufacturing process, or can be present at any stage after manufacturing until immediately before coating. Examples of the former include a silver halide grain formation process, a physical ripening process, and a chemical ripening process. That is, the sensitizing dye, antifoggant and stabilizer are
In addition to its original function, other properties such as strong adsorption to emulsions can be used to limit the formation position of chemically sensitized nuclei, or to stop excessive halogen conversion when obtaining bonded structure grains with different halogen compositions. It is also used to maintain the bonding structure of different types of halogens. Regarding these, JP-A-55-26589, JP-A-58-1119
No. 35, JP-A-58-28738, JP-A-62-70
40, U.S. Patent No. 3,628,960, U.S. Patent No. 4,2
The description in No. 25,666 can be referred to.

Chemical sensitization occurs when some or all of the sensitizing dyes, antifoggants, and stabilizers are added before adding the chemical sensitizer, and then the chemical sensitizer is added and chemical ripening is performed. Since the positions where the nuclei are formed on the silver halide grains are limited to areas where the sensitizing dye, antifoggant and stabilizer are not adsorbed, latent image dispersion is prevented and photographic properties are improved. Particularly preferred. Especially (111) of silver halide grains
It is particularly preferable to add a sensitizing dye, an antifoggant, and a stabilizer that are selectively adsorbed to the surfaces, since chemical sensitizing nuclei are formed only at the edges of the hexagonal tabular grains.

Generally, the above-mentioned additives are preferentially adsorbed on the crystal surfaces forming the main surfaces of the tabular grains, so that chemical sensitization nuclei are generated on different crystal surfaces of the tabular grains.

It is also effective to carry out chemical sensitization in the presence of a silver halide solvent. As the silver halide solvent used, thiocyanate and the solvents described in Japanese Patent Application No. 61-299155 can be used. The concentration of the solvent used is 10
-5 to 10-1 mol/u is preferable.

In combination with either or both of the above techniques,
or independently as a third technique, silver salts such as silver thiocyanate, silver phosphate, silver carbonate, etc., which may form a precipitate on the particle surface immediately before or during chemical sensitization. , and soluble silver salts such as silver acetate, silver trifluoroacetate, and silver nitrate, as well as finely divided silver halides (i.e., silver bromide,
Silver iodide and/or silver chloride) particles can be introduced. For example, Lippmann emulsions can be introduced during the chemical sensitization process.

The coating amount of the photosensitive silver halide used in the present invention is in the range of 1 mg to 10 g/rri' in terms of silver.

The emulsion of the present invention can be spectral sensitized by methods well known in the art.

The amount of sensitizing dye should be the amount that gives the highest negative blue sensitivity, but this amount is about the same as the amount that gives the highest negative blue sensitivity in surface latent image type emulsions, and it is far more than that amount. It is not preferable to add a large amount of sensitizing dye because it inhibits the development of the particles.

The sensitizing dye used in the present invention may be a known one, and includes, for example, cyanine dye, merocyanine dye, composite cyanine dye, composite merocyanine dye, holopolar cyanine dye, hemicyanine dye, styryl dye, and hemioxonol dye. . Particularly useful dyes are those belonging to the cyanine dyes, merocyanine dyes, and complex merocyanine dyes. Any of the nuclei commonly used for cyanine dyes can be used as the basic heterocyclic nucleus for these dyes. That is, pyrroline nucleus, oxazoline nucleus, thiazoline nucleus, virol nucleus, oxazole nucleus,
Thiazole nucleus, selenazole nucleus, imidazole nucleus, tetrazole nucleus, pyridine nucleus, etc.; Nuclei in which a finger ring hydrocarbon ring is fused to these nuclei; and a nucleus in which an aromatic hydrocarbon ring is fused to these nuclei, that is, indolenine nucleus , a benzindolenine nucleus, an indole nucleus, a benzoxadol nucleus, a naphthoxazole nucleus, a benzothiazole nucleus, a naphthothiazole nucleus, a benzoselenazole nucleus, a dizimidazole nucleus, a quinoline nucleus, etc. These nuclei may be substituted on carbon atoms.

Merocyanine dyes or complex merocyanine dyes include a pyrazolin-5-one nucleus, a thiohydantoin nucleus, and a 2-thioxazolidine-2,4 nucleus having a ketomethylene structure.
5- to 6-membered heterocyclic nuclei such as -dione nucleus, thiazolidine-2,4-dione nucleus, rhodanine nucleus, and thiobarbic acid nucleus can be applied.

Specifically, sensitizing dyes represented by the general formulas (A) to (Y) described in JP-A No. 61-193143 are mentioned.
More specifically, JP-A-60-133442 No. (8
) to (11), No. (5) of JP-A-61-75339
) to (7) pages, (24) to (25) pages, JP-A-1982-
No. 6251, pages (10) to (15), JP-A-59-2
No. 12827, pages (5) to (7), JP-A-1983-1
No. 22928, pages (7) to (9), JP-A-59-1
Sensitizing dyes for spectrally sensitizing silver halide in the blue region, edge region, red region, or infrared region of the spectrum, which are described in pages (7) to (18) of No. 80553, can be mentioned.

These sensitizing dyes may be used alone or in combination, and combinations of sensitizing dyes are often used particularly for the purpose of supersensitization.

Along with the sensitizing dye, the emulsion may contain a dye that does not itself have a spectral sensitizing effect or a compound that does not substantially absorb visible light and exhibits supersensitization (for example, as described in US Pat. No. 933.390, No. 3,635,
No. 721, No. 3,743,510, No. 3,615
．． No. 613, No. 3,615,641, No. 3,61
No. 7,295 and No. 3,635,721).

These sensitizing dyes may be added to the emulsion during or before or after chemical ripening.
It may be carried out before or after nucleation of silver halide grains according to No. 756 and No. 4,225.666.

In addition, when using two or more types of pigments together, they may be added as a mixture, added separately, or added one by one at different times; in the latter case, the above-mentioned method may be used. It may contain a compound exhibiting supersensitization.

Sensitizing dyes can be used in water-compatible organic solvents such as methanol, ethanol, propatool, fluorinated alcohols, methyl cellosolve, dimethylformamide, acetone, etc.
It may be added after being dissolved in a solution (which may be alkaline or acidic), or two or more of the above may be used in combination.

It may also be added in the form of a dispersion in a water/gelatin dispersion or in the form of a lyophilized powder.

Furthermore, the powder dispersed using a surfactant may be added in the form of a solution.

The amount of sensitizing dye used is to”a per mole of silver halide.
mol-10-2 mol is suitable, preferably 5 x 10
-6 to 5×10 −3 moles.

Further, the silver halide emulsion used in the present invention may be a system that is spectral 1-sensitized by an antenna dye. Regarding spectral sensitization using antenna dyes, reference can be made to the descriptions in Japanese Patent Application Nos. 61-51396, 61-284271, and 61-284272.

The emulsion of the present invention can be used in combination with a conventional so-called "surface latent image type emulsion" in the same emulsion layer. Further, the emulsion of the present invention and the above-mentioned conventional emulsion can be used alone between emulsion layers having the same color sensitivity or different color sensitivity.

The conventional silver halide photographic emulsion used in the present invention can be produced by a known method, for example, Research Disclosure, Vol. 176, No. 17643 (December 1978), pp. 22-23, ゛°I.
Preparation and Types)”
and Volume 187, No. 18716 (November 1979)
May), p. 648 can be followed.

The photographic emulsion used in the present invention is from "Physics and Chemistry of Photography" by Glafkide, published by Paul Montell (P, Glafkide).
s, Chimie et Physique Photo
ographique Paul Montel,
+967), Duffin, “Photographic Emulsion Chemistry J,” published by Focal Press (G.

F, Duffin, Photographic Em
ulion Chemistry (Foal Pres.
s, 1966), "Manufacture and Coating of Photographic Emulsions" by Zelikman et al., published by Focal Press (V., L., Zeli.
kman et al., Making and Co.
atingPhotographic Emulsio
It can be prepared using the method described in, for example, J.D., Focal Press, 1964).

As mentioned above, the heat-developable photosensitive element of the present invention basically has the above-described photosensitive silver halide and binder on a support.

Furthermore, if necessary, an organic metal salt oxidizing agent, a dye-donating compound (which may also serve as a reducing agent as described later), etc. can be contained.

These components are often added to the same layer, but if they are in a reactable state, they can be divided and added to separate layers. For example, when a colored dye-providing compound is present in the lower layer of the silver halide emulsion, it prevents a decrease in sensitivity.
Although the reducing agent is preferably incorporated into the photothermographic element, it may also be supplied from the outside, for example by diffusing it from a dye fixing element as described below.

In order to obtain a wide range of colors in the chromaticity diagram using the three primary colors yellow, magenta, and cyan, at least three silver halide emulsion layers each sensitive to a different spectral region are used in combination. For example, blue-sensitive layer, green-sensitive layer,
There are combinations of three layers including a red-sensitive layer, a green-sensitive layer, a red-sensitive layer, and an infrared-sensitive layer. Each photosensitive layer can be arranged in a variety of arrangements known from conventional color photosensitive elements. Further, each of these photosensitive layers may be divided into two or more layers as necessary. For example, each photosensitive layer may have two layers, a high-sensitivity layer and a low-sensitivity layer, or three layers, a high-sensitivity layer, a medium-sensitivity layer, and a low-sensitivity layer.

The heat-developable photosensitive element can be provided with various auxiliary layers such as a protective layer, an undercoat layer, an intermediate layer, a yellow filter layer, an antihalation layer, and a backing layer.

In the present invention, an organic metal salt can also be used as an oxidizing agent together with photosensitive silver halide. Among such organic metal salts, organic silver salts are particularly preferably used.

Organic compounds that can be used to form the organic silver salt oxidizing agent described above include U.S. Pat.
There are benzotriazoles, fatty acids and other compounds described in columns 53 and the like. Furthermore, silver salts of carboxylic acids having an alkynyl group such as silver phenylpropiolate described in JP-A No. 60-113235, and JP-A No. 61-249044
Also useful is acetylene silver, described in No. Two or more types of organic silver salts may be used in combination.

The above-mentioned organic silver salts contain, per mol of photosensitive silver halide,
0.01 to 10 mol, preferably 0.01 to 1
Moles can be used together. The total coating amount of photosensitive silver halide and organic silver salt is 50 mg to 10 g in terms of silver.
/m” is appropriate.

Various antifoggants or photographic stabilizers can be used in the present invention. An example is RD17
643 (1978) pages 24-25, nitrogen-containing carboxylic acids and phosphoric acids described in JP-A-59-168442, or mercapto compounds and their Metal salts, acetylene compounds described in JP-A No. 62-87957, and the like are used.

As the reducing agent used in the present invention, those known in the field of heat-developable photosensitive elements can be used. Further, a dye-donating compound having reducing properties, which will be described later, is also included (in this case, other reducing agents can also be used in combination).
Further, a reducing agent precursor that does not itself have reducing properties but exhibits reducing properties by the action of a nucleophile or heat during the development process can also be used.

Examples of reducing agents used in the present invention include U.S. Pat.
, No. 500,826, columns 49-50, same No. 4,483
, No. 914, columns 30-31, same No. 4,330,617
No. 4,590.152, JP-A-60-1403
No. 35, pages (17) to (18), 57-40245
No. 56-138736, No. 59-178458, No. 59-53831, No. 59-182449, No. 59-182450, No. 60-119555, No. 6
From No. 0-128436 to No. 60-128439,
No. 60-198540, No. 60-181742, No. 61-259253, No. 62-244044, No. 6
There are reducing agents and reducing agent precursors described in European Patent No. 220,746A2, pages 78 to 96, from No. 2-131253 to No. 62-13'1256.

Combinations of various reducing agents can also be used, such as those disclosed in US Pat. No. 3,039,869.

If a diffusion-resistant reducing agent is used, an electron transfer agent and/or electron transfer agent is optionally added to facilitate electron transfer between the diffusion-resistant reducing agent and the developable silver halide. Combinations of precursors can be used.

The electron transfer agent or its precursor can be selected from the aforementioned reducing agents or its precursors.
It is desirable that the mobility of the electron transfer agent or its precursor is greater than that of the diffusion-resistant reducing agent (electron donor).

Particularly useful electron transfer agents are 1-phenyl-3-pyrazolidones or aminophenols.

The diffusion-resistant reducing agent (electron donor) used in combination with the electron transfer agent may be one of the above-mentioned reducing agents as long as it does not substantially migrate in the layer of the photosensitive element, and preferably hydroquinones, Examples include sulfonamide phenols, sulfonamide naphthols, compounds described as electron donors in JP-A-53-110827, and dye-donating compounds with diffusion resistance and reducing properties described below.

In the present invention, the amount of reducing agent added is 0 per mole of silver.
．． 01 to 20 mol, particularly preferably 0.1 to 10 mol.

In the present invention, silver can be used as the image forming material. In addition, when silver ions are reduced to silver under high temperature conditions, a compound that generates or releases a mobile (diffusible) dye in response to or inversely to this reaction, that is, a dye-donating compound. It can also contain.

Examples of dye-providing compounds used in the present invention include compounds (couplers) that form dyes through oxidative coupling reactions. The coupler may be a 4-equivalent coupler or a 2-equivalent coupler. Also preferred are two-equivalent couplers that have a diffusion-resistant group as a leaving group and form a diffusible dye through an oxidative coupling reaction.
Specific examples of developers and couplers can be found in "The Theory of the Photographic Process" by James, 4th edition (T.H.).

James “The Theory of
the Photographic Process
'') pp. 291-334 and 354-361, JP-A No. 58-123533, No. 5B-149046, No. 5
No. 8-149047, No. 59-111148, No. 59
-124399, 59-174835, 59-
No. 231539, No. 59-231540, No. 60-2
950, No. 60-2951, No. 60-14242, No. 60-23474, No. 60-66249, Japanese Patent Publication No. 52-24849, Japanese Patent Application Laid-open No. 53-129036, etc.

Further, as another example of the dye-providing compound, there can be mentioned a compound having a function of releasing or diffusing a diffusible dye in an imagewise manner. This type of compound can be represented by the following general formula (Ll).

(Dye-Y)n Z (Ll)Dye
represents a dye group, -temporally shortened dye group or dye precursor group, Y represents a mere bond or linking group,
Z corresponds to or inversely corresponds to the photosensitive silver salt having a latent image (Dye-Y), or causes a difference in the diffusivity of the compound represented by 71-Z, or releases Dye and releases it. represents a group having a property that causes a difference in diffusivity between Dye and (Dye-Y)1-Z, n represents 1 or 2, and when n is 2, two Dye
-Y may be the same or different.

Specific examples of the dye-providing compound represented by the general formula (Ll) include the following compounds (1) to (2).

Note that ■ to ■ below correspond inversely to the development of silver halide to form a diffusible dye image (positive dye image), and ■ and ■ correspond to the development of silver halide to form a diffusible dye image. It forms a dye image (negative dye image).

■U.S. Patent No. 3,134,764, U.S. Patent No. 3.362,
No. 819, No. 3,597,200, No. 3,544
, No. 545, No. 3,482.972, etc., in which a hydroquinone developer and a dye component are linked can be used. This dye developer is diffusible in an alkaline environment, but becomes non-diffusible when it reacts with silver halide.

■As described in US Pat. No. 4,503,137, etc., non-diffusible compounds that release diffusible dyes in an alkaline environment but lose this ability when reacted with silver halide can also be used.

Examples include compounds that release diffusible dyes through intramolecular nucleophilic substitution reactions described in U.S. Patent No. 3,980,479, and isoxacilone rings described in U.S. Pat. Examples include compounds that release diffusible dyes through intramolecular rewinding reactions.

■US Patent No. 4,559,290, European Patent No. 220
, No. 746A2, Technical Report No. 87-6199, non-diffusible compounds that are not oxidized by development and react with the remaining reducing agent to release a diffusible dye can also be used.

Examples include U.S. Patent No. 4,139,389, U.S. Pat.
No. 57-84453, etc., a compound that releases a diffusible dye by an intramolecular nucleophilic substitution reaction after being reduced, U.S. Patent No. 4,232,107, JP-A-59
-101649, 61-88257, RD240
25 (1984), etc., a compound that releases a diffusible dye by an intramolecular electron transfer reaction after being reduced, West German Patent No. 3,008.588A, JP-A-1988-1
No. 42530, U.S. Pat. No. 4,343,893, U.S. Pat. Nitro compounds that release diffusible dyes after accepting electrons, as described in U.S. Pat.
Examples include compounds that release a diffusible □ dye after accepting electrons, as described in No. 609,610.

Also, more preferably, European Patent No. 220.7
No. 46A2, Public Technical Report 87-6199, Patent Application 1986-3
Compounds having an N-X bond (X represents oxygen, sulfur, or nitrogen atom) and an electron-withdrawing group in one molecule, as described in No. 4953, No. 62-34954, etc., patent application No. 62-106
Compound having 802-X (X has the same meaning as above) and an electron-withdrawing group in one molecule described in No. 885, patent application No. 1982-1
A compound having a po-x bond (X has the same meaning as above) and an electron-withdrawing group in one molecule described in No. 06895, patent application No. 6
Examples include compounds having a c-x' bond (X' is synonymous with X or represents -302-) and an electron-withdrawing group in one molecule as described in No. 2-106887.

Among these, compounds having an N-X bond and an electron-withdrawing group in the -molecule are particularly preferred. A specific example is European Patent No. 2
Compounds (1) to (3) described in 20.746A2
, (7) to (10), (12), (13), (15),
(23) to (26), (31), (32), (35),
(36), (40), (41), (44), (53)~
(59), (64), (70), Technical Report 87-619
9, compounds (11) to (23), and the like.

■A compound that is a coupler that has a diffusible dye as a leaving group and releases the diffusible dye upon reaction with the oxidized form of a reducing agent (D
DR coupler) can be used. Specifically, British Patent No. 1,330°524, Japanese Patent Publication No. 4B-39165,
U.S. Patent No. 3,443,940, U.S. Patent No. 4,474°8
There are those described in No. 67, No. 4,483,914, etc.

■Reducing to silver halide or organic silver salt,
Compounds that release diffusible dyes upon reduction of their partner (DRR)
compounds) can be used.

Since this compound does not require the use of any other reducing agent, it is preferable since there is no problem of image staining due to oxidative decomposition products of the reducing agent. A typical example is U.S. Patent No. 3,928,312
No. 4.053.312, No. 4,055,42
No. 8, No. 4,336,322, JP-A-59-658
No. 39, No. 59-6983-9, No. 53-3819, No. 51-104343, RD17465, U.S. Patent No. 3,725,062, No. 3,728,113, No. 3,443 , No. 939, JP-A-58-11653
No. 7, No. 57-179840, U.S. Patent No. 4,500
, No. 626, etc. Specific examples of DRR compounds include the compounds described in columns 22 to 44 of the aforementioned U.S. Pat. No. 4,500°626, among which compounds (1) to (
3), (10) to (13), (16) to (19), (
28) ~ (30), (33) ~ (35), (38) ~ (
40), (42) to (64) are preferred. Also useful are the compounds described in U.S. Pat. No. 4,639,408, columns 37-39.

In addition, as dye-donating compounds other than the couplers and general formula (LI) mentioned above, dye silver compounds in which an organic silver salt and a dye are combined (Research Disclosure Magazine 1978
May issue, pages 54-58), azo dyes used in heat-developable silver dye bleaching methods (US Pat. No. 4,235.957, etc.),
Research Disclosure magazine, April 1976 issue,
30-32), leuco dye (U.S. Pat. No. 3,985)
, No. 565, No. 4゜022.617, etc.) can also be used.

Hydrophobic additives such as the dye-providing compounds and diffusion-resistant reducing agents described above can be incorporated into the layers of the photosensitive element by known methods such as those described in U.S. Pat. No. 2,322,027. In this case, Japanese Patent Application Laid-Open No. 59-83154,
No. 59-178451, No. 59-178452, No. 59-178453, No. 59-178454, No. 5
9-178455, 59-178457, etc., if necessary, at a boiling point of 50°C.
It can be used in combination with a low boiling point organic solvent of ~160°C.

The amount of high-boiling organic solvent is 1 g of the dye-donating compound used.
to3 or less, preferably 5g or less. Also, lcc or less, and even 0.1cc per 1g of binder.
5 cc or less, particularly 0.3 cc or less is suitable.

Dispersion methods using polymers described in Japanese Patent Publication No. 51-39853 and Japanese Patent Application Laid-Open No. 51-59943 can also be used.

In the case of a compound that is substantially insoluble in water, it can be dispersed and contained in the form of fine particles in the binder in addition to the method described above.

Various surfactants can be used when dispersing hydrophobic compounds in hydrophilic colloids. For example, JP-A-5
The surfactants listed on pages (37) to (38) of No. 9-157636 can be used.

In the present invention, a compound that activates development and simultaneously stabilizes images can be used in the photosensitive element. For specific compounds preferably used, see U.S. Patent Nos. 4 and 5.
No. 00,626, columns 51-52.

In systems that form images by diffusion transfer of dyes, dye-fixing elements are used in conjunction with photosensitive elements. The dye fixing element may be coated separately on a support separate from the photosensitive element, or may be coated on the same support as the photosensitive element. Regarding the relationship between the photosensitive element and the dye fixing element, the relationship with the support, and the relationship with the white reflective layer, the relationships described in column 57 of US Pat. No. 4,500,626 can be applied to the present application.

The dye fixing element preferably used in the present invention has at least one layer containing a mordant and a binder, that is, a dye fixing layer. As the mordant, those known in the photographic field can be used, and specific examples thereof include U.S. Pat.
Mordants described in columns 58 to 59 of No. 626 and pages (32) to (41) of JP-A No. 256-256;
Examples include those described in No. 244043 and No. 62-24403.

Also, dye-receiving polymeric compounds such as those described in US Pat. No. 4,463,079 may be used.

The dye fixing element can be provided with auxiliary layers such as a protective layer, a release layer, an anti-curl layer, and an undercoat layer, if necessary.

It is particularly useful to provide a protective layer.

Hydrophilic binders are preferably used for the constituent layers of the photosensitive element of the present invention and the dye fixing element used in combination therewith. An example of this is JP-A No. 62-253159.
Examples include those described on pages (26) to (28) of the issue. Specifically, transparent or translucent hydrophilic binders are preferred, and include natural compounds such as proteins or cellulose derivatives such as gelatin and gelatin derivatives, polysaccharides such as starch, gum arabic, dextran, and pullulan, and polyvinyl alcohol, Examples include polyvinylpyrrolidone, acrylamide polymer, and other synthetic polymer compounds. In addition, super absorbent polymers described in JP-A No. 62-245260, i.e. homopolymers of vinyl monomers having -COOM or -3O3M (M is a hydrogen atom or an alkali metal), or combinations of these vinyl monomers or other Copolymers with vinyl monomers (eg, sodium methacrylate, ammonium methacrylate, Sumikagel L-5H manufactured by Sumitomo Chemical ■) are also used.

Two or more of these binders can also be used in combination.

When employing a system that performs thermal development by supplying a small amount of water, the use of the above-mentioned super absorbent polymer makes it possible to quickly absorb water. Furthermore, when a highly water-absorbing polymer is used in the dye-fixing layer or its protective layer, it is possible to prevent the dye from being retransferred from the dye-fixing element to another object after transfer.

In the present invention, the amount of binder applied is preferably 20 g or less per lrn'', particularly 10 g or less, and more preferably 7 g.
It is appropriate to do the following.

Hardeners used in the constituent layers of light-sensitive elements and dye-fixing elements include U.S. Pat.
Examples include hardeners described in No. 1-18942 and the like. More specifically, aldehyde hardeners (such as formaldehyde), aziridine hardeners, and epoxy hardeners (CH2
-CH-CH2-0-(CH2) a -0-C)
12\1-co-co2, etc.)\1 Vinylsulfone hardeners (N,N'-ethylene-bis(vinylsulfonylacetamido)ethane, etc.), N-methylol hardeners (dimethylolurea, etc.), Alternatively, polymer hardeners (compounds described in JP-A No. 62-234157, etc.) may be used.

An image formation accelerator can be used in the photosensitive element of the present invention and/or the dye fixing element used in combination therewith. Image formation accelerators include accelerating redox reactions between silver salt oxidizing agents and reducing agents, accelerating reactions such as generation of dyes from dye-donating substances, decomposition of dyes, and release of diffusible dyes, and photosensitive element layers. It has functions such as promoting the movement of dye from the dye fixing layer to the dye fixing layer, and from a physicochemical function, it has the following functions: base or base precursor, nucleophilic gold compound, high-boiling organic solvent (oil), thermal solvent, surfactant, It is classified as a compound that interacts with silver or silver ions. However, these substance groups generally have multiple functions and usually have some of the above-mentioned promoting effects. For further details see U.S. Pat. No. 4,678,739, 38-40.
column.

Examples of base precursors include salts of organic acids and bases that are decarboxylated by heat, compounds that release amines by intramolecular nucleophilic substitution reaction, Rossen rearrangement, or Beckmann rearrangement. Specific examples thereof are described in U.S. Pat.

In a system in which thermal development and dye transfer are performed simultaneously in the presence of a small amount of water, it is preferable to include a base and/or a base precursor in the dye fixing element in order to improve the storage stability of the photosensitive element.

In addition to the above, combinations of poorly soluble metal compounds and compounds that can undergo complex formation reactions with metal ions constituting the poorly soluble metal compounds (referred to as complex-forming compounds), as described in European Patent Publication 210,860, and special Kaisho 61-232451
Compounds that generate bases by electrolysis, such as those described in this issue, can also be used as base precursors.

The former method is particularly effective. It is advantageous to add the poorly soluble metal compound and the complex-forming compound to the light-sensitive element and the dye-fixing element separately.

In the dye fixing element of the present invention and/or the dye fixing element used in combination therewith, various development stoppers may be used in order to always obtain a constant image despite fluctuations in processing temperature and processing time during development. Can be done.

The term "development stopper" as used herein refers to a compound that immediately neutralizes or reacts with a base to reduce the base concentration in the film and stop development after proper development, or a compound that interacts with silver and silver salts to stop development. It is an inhibitory compound. Specific examples include acid precursors that release acids when heated, electrophilic compounds that undergo a substitution reaction with a coexisting base when heated, nitrogen-containing heterocyclic compounds, mercapto compounds, and their precursors. More details are described in JP-A No. 82-253159 (pages 311-(32)).

The constituent layers (including the back layer) of the photosensitive element of the present invention or the dye fixing element used in combination therewith include dimensional stabilization,
Various polymer latexes can be contained for the purpose of improving the physical properties of the film, such as preventing curling, preventing adhesion, preventing cracking of the film, and preventing pressure sensitivity. Specifically, JP-A-62
-245258, 62-136648, 62-
Any of the polymer latexes described in No. 110066 and the like can be used. In particular, using a polymer latex with a low glass transition point (below 40°C) for the mordant layer can prevent cracking of the mordant layer, and using a polymer latex with a high glass transition point for the back layer can prevent curling. can get.

In the constituent layers of the photosensitive element of the present invention and the dye fixing element used in combination therewith, a high boiling point organic solvent can be used as a binder agent, a slippery agent, or a peelability improving agent between the photosensitive element and the dye fixing element. . Specifically, JP-A-62-2
There are those described in No. 53159, page (25), No. 62-245253, etc.

Furthermore, various silicone oils (
All silicone oils can be used, from dimethylsilicone oil to modified silicone oils in which various organic groups are introduced into dimethylsiloxane. Examples include various modified silicone oils, especially carboxy-modified silicone (product name: X-22-3
710) etc. are effective. Also, JP-A-62-215
Silicone oils described in No. 953 and Japanese Patent Application No. 62-23687 are also effective.

An antifading agent may be used in the photosensitive element of the present invention or the dye fixing element used in combination therewith.

Antifading agents include, for example, antioxidants, ultraviolet absorbers, or certain metal complexes.

Examples of antioxidants include chroman compounds, coumaran compounds, phenol compounds (for example, hindered phenols), hydroquinone derivatives, hindered amine derivatives, and spiroindane compounds. Compounds described in JP-A-61-159644 are also effective.

Benzotriazole compounds (
U.S. Patent No. 3,533,794, etc.), 4-thiazolidone compounds (U.S. Patent No. 3,352,681, etc.)
, and other JP-A-54-48535, JP-A No. 62-1366
There are compounds described in No. 41, No. 61-88256, and the like. Further, the ultraviolet absorbing polymer described in JP-A No. 62-260152 is also effective.

As metal complexes, U.S. Pat. No. 4,241°155;
No. 4,245,018, columns 3 to 36, No. 4,25
No. 4,195, columns 3 to 8, JP-A-50-87649,
No. 62-174741, No. 61-88256 (2
Pages 7) to (29), Patent Application No. 1983-234103, No. 6
There are compounds described in Japanese Patent Application No. 2-31096, Japanese Patent Application No. 62-230596, etc.

Examples of useful antifading agents are described in JP-A-62-215272, pages (125) to (137).

The antifading agent for preventing fading of the dye transferred to the dye fixing element may be contained in the dye fixing element in advance, or may be supplied to the dye fixing element from outside such as a photosensitive element. .

The above antioxidants, ultraviolet absorbers, and metal complexes may be used in combination.

A fluorescent brightener may be used in the photosensitive element of the present invention or the dye fixing element used in combination therewith.

In particular, it is preferable to incorporate the fluorescent whitening agent into the dye-fixing element or to supply it from outside the photosensitive element. Examples include K. Veenkataraman, ed.
e Chemistry of 5ynthetic
Dyes J Volume V Chapter 8, JP-A-61-143752
Examples include compounds described in No.

More specifically, examples include stilbene compounds, coumarin compounds, biphenyl compounds, benzoxacylyl compounds, naphthalimide compounds, pyrazoline compounds, and carbostyryl compounds.

Optical brighteners can be used in combination with antifade agents.

Various surfactants are used in the constituent layers of the photosensitive element of the present invention and the dye fixing element used in combination therewith for the purposes of coating aids, improving peelability, improving slipperiness, preventing static electricity, promoting development, etc. be able to. Specific examples of surfactants are given in Japanese Patent Application Laid-open No. 6
It is described in No. 2-173463, No. 62-183457, etc.

The constituent layers of the photosensitive element of the present invention or the dye fixing element used in combination therewith may contain an organic fluoro compound for the purpose of improving slipperiness, preventing static electricity, improving releasability, and the like. Representative examples of organic fluoro compounds include Japanese Patent Publication No. 57-90
No. 53, columns 8 to 17, JP-A No. 61-20944, No. 6
2-135826, hydrophobic fluorine compounds such as oily fluorine compounds such as fluorine oil, or solid fluorine compound resins such as tetrafluoroethylene resin.

A matting agent can be used in the photosensitive element of the present invention and the dye fixing element used in combination therewith. As matting agents, in addition to the compounds described in JP-A-61-88256, page (29) such as silicon dioxide, polyolefin, or polymethacrylate, there are also compounds such as benzoguanamine resin beads, polycarbonate resin beads, AS resin beads, etc. There are compounds described in No. 110064 and No. 62-110065.

In addition, the constituent layers of the photosensitive element of the present invention and the dye fixing element used in combination therewith may contain a thermal solvent, an antifoaming agent, an antibacterial and antibacterial agent, colloidal silica, and the like. Specific examples of these additives are given in JP-A No. 81-88256 (2).
It is described on pages 6) to (32).

As the support for the photosensitive element of the present invention and the dye fixing element used in combination therewith, those that can withstand processing temperatures are used. -For boat fishing, paper and synthetic polymers (films) can be used. Specifically, films made from polyethylene terephthalate, polycarbonate, polyvinyl chloride, polystyrene, polypropylene, polyimide, celluloses (e.g. triacetyl cellulose), films containing pigments such as titanium oxide, and polypropylene, etc. film method synthetic paper,
Mixed paper made from synthetic resin bulbs such as polyethylene and natural pulp, Yankee paper, baryta paper, coachite paper (particularly cast coated paper), metal, cloth, glass, etc. are used.

These can be used alone, or can be used as a support laminated on one or both sides with a synthetic polymer such as polyethylene.

In addition, JP-A No. 62-253159 (291-(
The supports described on page 31) can be used.

A hydrophilic binder, alumina sol, a semiconductive metal oxide such as tin oxide, carbon black or other antistatic agent may be applied to the surface of these supports.

Methods for exposing and recording images on the photosensitive element of the present invention include, for example, directly photographing landscapes and people using a camera, exposing through reversal film or negative film using a printer or enlarger, etc. A method of scanning and exposing an original image through a slit using an exposure device of a copying machine, a method of transmitting image information via an electric signal to a light emitting diode, various lasers, etc., a method of transmitting image information to a CRT, liquid crystal display, etc. There is a method of outputting the image to an image display device such as an electroluminescence display or a plasma display and exposing it directly or through an optical system.

Light sources for recording images on the photosensitive element include natural light, tungsten lamps, light emitting diodes, laser light sources, CRT light sources, etc., as mentioned above, such as U.S. Pat. No. 4,500,8
The light source described in No. 26, column 56 can be used.

The above-mentioned image information includes image signals obtained from video cameras, electronic still cameras, etc., television signals represented by the Nippon Television Signal Standard (NTSC), and images obtained by dividing an original image into a large number of pixels using a scanner. signal, CG, C
Image signals created using a computer such as AD can be used.

The heating temperature in the heat development step can be developed at about 0°C to about 250°C, and particularly useful is about 0°C to about 180°C. The dye diffusion transfer step may be performed simultaneously with the heat development, or may be performed after the heat development step is completed. In the latter case, the heating temperature in the transfer step can be in the range from the temperature in the heat development step to room temperature, but is particularly preferably 50° C. or higher and up to about 10° C. lower than the temperature in the heat development step.

Dye migration can also be caused by heat alone, but a solvent may be used to promote dye migration.

Also, JP-A-59-218443, JP-A No. 61-2380
56, etc., a method in which development and transfer are performed simultaneously or continuously by heating in the presence of a small amount of solvent (particularly water) is also useful. In this method, the heating temperature is preferably 50° C. or higher and below the boiling point of the solvent. For example, when the solvent is water, it is preferably 50° C. or higher and 100° C. or lower.

Examples of solvents used to accelerate development and/or transfer the diffusible dye to the dye fixing layer include water or basic aqueous solutions containing inorganic alkali metal salts or organic bases (these bases may Those described in the section on formation promoters can be used. Furthermore, a low boiling point solvent or a mixed solution of a low boiling point solvent and water or a basic aqueous solution can also be used. Further, a surfactant, an antifoggant, a complex-forming compound with a sparingly soluble metal salt, etc. may be included in the solvent.

These solvents can be used in a method in which they are applied to a dye-fixing element, a photosensitive element, or both. The amount used is less than or equal to the weight of the solvent corresponding to the maximum swelling volume of the entire coated film (
In particular, a small amount (not more than the amount obtained by subtracting the weight of the entire coating film from the weight of the solvent corresponding to the maximum swelling volume of the entire coating film) may be sufficient.

As a method for applying a solvent to the photosensitive layer or the dye fixing layer, there is, for example, the method described in JP-A-61-147244 (page 261). Alternatively, it can also be used by incorporating it into the dye fixing element or both.

Further, in order to promote dye transfer, a method may be adopted in which a hydrophilic thermal solvent that is solid at room temperature and dissolves at high temperature is incorporated into the photosensitive element or dye fixing element. The hydrophilic thermal solvent may be incorporated into either the photosensitive element or the dye fixing element.
It may be built into both. Further, the layer to be incorporated may be any of an emulsion layer, an intermediate layer, a protective layer, and a dye fixing layer, but it is preferably incorporated in the dye fixing layer and/or a layer adjacent thereto.

Examples of hydrophilic heat solvents include ureas, pyridines, amides, sulfonamides, imides, alnyls, oximes, and other heterocycles.

Further, in order to promote dye transfer, a high boiling point organic solvent may be contained in the photosensitive element and/or the dye fixing element.

Heating methods in the development and/or transfer process include contact with a heated block or plate, hot plate, hot breather, heat roller, halogen lamp heater, infrared and far-infrared lamp heater, etc. or passing through a high-temperature atmosphere. In addition, a resistive heating element layer is provided on the photosensitive element or the dye fixing element,
It may be heated by applying electricity to it.

As the heat generating layer, those described in JP-A-61-145544 and the like can be used.

As for the pressure conditions and the method of applying pressure when the photosensitive element of the present invention and the dye fixing element used in combination are superimposed and brought into close contact, the method described in JP-A-61-147244, page (27) can be used. .

Any of a variety of thermal development equipment can be used to process photographic elements constructed from the light-sensitive elements of this invention and the dye-fixing elements used in combination therewith. For example, JP-A-59-7
No. 5247, No. 59-177547, No. 59-181
No. 353, No. 60-18951, Utility Model Application No. 62-259
The apparatus described in No. 44 and the like is preferably used.

(2) Specific effects of the invention According to the invention, it is possible to obtain images with high sensitivity and less fog during thermal development.

(2) Specific Examples of the Invention Hereinafter, specific examples of the present invention will be shown and the present invention will be explained in more detail.

Example 1 Twelve types of silver iodobromide emulsions (iodine content: 3 mol %) as shown in Table 1 were prepared.

Table 1 2! J 拉1'' I Trial ienoni Q and L A (invention) Cube 0.7 B (comparison) Cube 0.7 0 (invention) Cube 0.7 D (comparison) Cube 0.7 E (comparison) Cube 0.7 F (comparison) Cube 0.7 G (invention) Cube 0.3 H (comparison) Cube Q, 3 I (invention) Cube 0.9 J (comparison) Cube 0.9 K (comparison) Cube 1.1 L (invention) Octahedron 0. 7M (comparison) Octahedron O0゛7 N (Invention) Octahedron 0. 70 (Comparative) Octahedron 0.7 The preparation method of these emulsions is described below.

(2) Preparation of a monodispersed emulsion having a (100) crystal habit: KBr and a silver nitrate aqueous solution while maintaining pBr at 4.5 in an aqueous gelatin solution kept at 70°C.

Add an aqueous solution containing Kl using a double jet 100)
A monodisperse emulsion (head length 0.68 μm) having a crystal habit was prepared. Next, this core emulsion was divided into three parts and shells were formed under the following separate conditions, and the final grain size was adjusted to 0.7.
The μm%AgI content was 3 mol%.

(Emulsion A) Sodium thiosulfate and potassium chloroaurate were added to the above core to perform chemical sensitization.

Thereafter, the shell was precipitated under the same conditions as for core formation.

(Emulsion B) After a shell was precipitated on the above core under the same conditions as in Emulsion A, chemical sensitization was performed.

(Emulsion C) The above core was subjected to chemical sensitization and shell precipitation in the same manner as Emulsion A, and then further chemical sensitization was performed.

(Emulsion D) An emulsion was prepared under the same conditions as Emulsion A except that a core smaller in size than that used in preparing Emulsions A to C was used.

(Emulsion E) Emulsion E was prepared under the same conditions as the emulsion except that the shell was precipitated under conditions where the pBr was increased to 5.0 and the solubility of silver halide was increased.

(Emulsion F) Emulsion F was prepared under the same conditions as Emulsion A, except that the shell was precipitated under conditions in which the pBr was lowered to 4.0 and the solubility of silver halide was lowered.

(Emulsions G and I) Emulsions having the same latent image distribution and final average grain sizes of 0.3 μm and 0.9 μm were prepared in the same manner as Emulsion A and designated as Emulsions G and I, respectively.

(Emulsions H, J, K) The final average grain size was 0.3μm, 0.9μm with the same latent image distribution as emulsion B.
m and 1.1 μm emulsions were prepared, and emulsions H and 'J
, Nitoshi.

■Preparation of monodisperse emulsion with (111) crystal habit Emulsion A, B
, C, and D were prepared in the same manner as before except that the pBr was changed to 3.3 during particle formation.

Monodisperse octahedral emulsions corresponding to B, C, and D and differing only in crystal habit were prepared, and emulsions M and N were prepared, respectively.

It was set to 0.

Sensitizing dye S-1 was added to the above emulsion and coated in an amount of 2 μg of silver per square centimeter. Emulsion A, B, C
, D, E, and F coating samples are shown in FIG. 1.

Next, we will describe how to make a gelatin dispersion of a dye-providing compound.

13 g of yellow dye-donating compound (1), 6.5 g of high-boiling organic solvent (1), and electron donor (ED-1)6.
Add and dissolve 5g in 37ml 1J of cyclohexanone,
% gelatin solution and 2.5% aqueous solution 6011112 of sodium dodecylbenzenesulfonate with stirring, and then mixed with a homogenizer for 10 minutes at 110,000 rpm.
It was dispersed.

This dispersion is called a yellow dye-providing compound dispersion.

Magenta dye-donating compound (2) 16.8g 1 high boiling point organic solvent (1) 8.4g and electron donor (ED-1)
Add and dissolve 6.3 g in 37 m5 I of cyclohexanone, stir and mix with 100 g of 10% gelatin solution and 60 g of 2.5% aqueous solution of sodium dodecylbenzenesulfonate, and then heat with a homogenizer for 10 minutes at 110,000 r.
Dispersed at p. This dispersion is called a dispersion of a magenta dye-providing compound.

15.4 g of cyan dye-providing compound (3), high boiling point organic solvent (1)7. 7g and electron donor (ED-1)
6.0g was added to 37g of cyclohexanone and dissolved, 10g
After stirring and mixing 100 g of % gelatin solution and 60 m of a 2.5% aqueous solution of sodium dodecylbenzenesulfonate,
Dispersion was performed using a homogenizer for 10 minutes at 110,000 rpm.

This dispersion is referred to as a dispersion of a cyan dye-providing compound.

From these, photosensitive elements as shown in Table 2 were produced.

The emulsions used are shown in Table 3.

0:0: ψ Q = C's Kodo 0 E 0 2:11's = -〇Table 2 Table 2 (Continued 1) Table 2 (Continued 2) Support (polyethylene terephthalate; thickness 1ooμ)
Water-soluble polymer (1) Medium Sumikagel L-5 (H) Made by Sumitomo Chemical ≧ u3 Surfactant (1) Medium aerosol OT ethane High boiling point organic solvent (1)! Tricyclohexylphosphate antifoggant (2) Middle ■ Electron donor (ED-1)! Electron transfer agent (X)! Reducing agent (ED-2) to H! Sensitizing dye (o-g sensitizing dye (D-2) Umbrella sensitizing dye (D-3) Umbrella silicone oil *1 Surfactant *2 Aerosol OT Kazusurfactant Medium 4 C11H23CONHCH2 polymer Umbrella 5 Vinyl alcohol acrylic Dextran (molecular weight 7) = 00 sodium nitrate copolymer (75725 molar ratio) C5) A tungsten bulb was used for each of the color photosensitive elements with the above multilayer structure, and the concentration was continuously changed. B, G , R and Gray color separation filters at 5000 lux for 1/1o second.

While feeding this exposed photosensitive element at a linear speed of 20 mm/sec, 15 m$1/rn'' of water was supplied to the emulsion surface using a wire bar, and then the dye-fixing element was immediately superimposed so that the membrane surface was in contact with the element. Ta.

The film was heated for 20 seconds using a heat roller whose temperature was adjusted so that the temperature of the water-absorbed film was 85°C. Next, when peeled off from the dye fixing element, B, G%R
Clear positive images of blue, green, red, and gray were evenly obtained in response to color separation filters of 1 and 2 and gray.

Table 5 shows the results of measuring the maximum density (Dmax), minimum density (Dmin), and sensitivity of each color of cyan, magenta, and yellow in the gray part. Here, the sensitivity is Dmax and D
It is expressed as a relative value of the reciprocal of the exposure amount that gives an intermediate density of min.

From the results in Table 5, it can be seen that the photosensitive elements using the emulsions of the present invention have high sensitivity and high maximum density, which indicates that there is little fog during thermal development.

Example 2 A photosensitive element was prepared which was exactly the same as the photosensitive element 101 of Example 1 described in JP-A-62-253159, except that emulsions (I), (rV), and (■) were changed as shown in Table 6. did.

Table 6 A', B5, C8, and B8 show the molar ratio of sensitizing dye D-4 to silver after preparing emulsions A, B, C, and D, respectively. , 0X10-' is added to the emulsion.

Sensitizing Dye D-4 This multilayered color photosensitive element 201-204 was exposed for 10-4 seconds using a xenon flash tube. At that time, exposure was performed through a three-color separation filter of green (G), red (R), and infrared (IR) whose density was continuously changed.

12 min 2 of water was supplied to the emulsion surface of the exposed light-sensitive element using a wire bar, and then the element was superimposed on the dye-fixing element described above so that the film surface was in contact with the element.

A negative image of yellow, magenta, and cyan film surface corresponding to the three-color separation filter of G%R and IR was obtained. Measure the maximum density (Dmax) and minimum density (Dmin) of each color using a Macbeth reflection densitometer (RD-519)
Measured using

In addition, sensitivity was measured using the relative value of the reciprocal of the exposure amount that gives a density of fog +0.2.

The results are shown in Table 7.

From the results in Table 7, photosensitive element 201 using the emulsion of the present invention
．． It can be seen that Emulsion No. 203 is an excellent emulsion that has higher sensitivity than the comparative ones, has a lower minimum density, and has less fog during thermal development.

[Brief explanation of the drawing]

Figure 1 shows the development distribution, and the horizontal axis X is the depth of the latent image (μ
m), and the vertical axis y represents the number of latent images. , Nei R- Patent attorney Yo Ishii - To 1.
:〒. FIG, 1 0 0.005 0.010 0.015
0.020 04) 25 deep; X (pm)

Claims (1)

[Claims] (1) In a heat-developable photosensitive element having at least a silver halide emulsion and a binder on a support, at least 50% of the silver halide emulsion has at least one maximum value inside the grains in its latent image distribution. A photothermographic element characterized in that the position of this maximum value is located at a depth of less than 0.02 μm from the surface, and the element is chemically sensitized so that the particle surface also has a latent image.