JPS6337368B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a heat-developable photosensitive material. Heat-developable photosensitive materials and methods for preparing them are already known. After imagewise exposure, such heat-developable photosensitive materials are generally heated to form a developed image in the absence of a separate processing solution. This heat-developable photosensitive material consists of an organic silver salt, a reducing agent, and a silver halide in catalytic contact with the organic silver salt.
No., Japanese Patent Publication No. 44-26582, and Japanese Patent Application Laid-open No. 46-6074. In addition to the above, heat-developable photosensitive materials that are activated and made photosensitive by heat treatment before imagewise exposure and then heated as a whole to form a developed image after imagewise exposure; A method of preparation has been proposed. This heat-developable photosensitive material consists of a heat-developable photosensitive element that does not contain silver halide or has no photosensitivity even if it contains silver halide. No. 29819, Special Publication No. 53-41967, Special Publication No. 1977
-Described in each publication No. 5687. While the above-mentioned heat-developable photosensitive materials have the advantage of not requiring a wet process for image formation, it is also true that improvements in sensitivity and thermal fog are insufficient, which is a major obstacle in practical use. . In particular, the causes of thermal fogging depend on various factors, but can be said to be due to the inclusion of an organic silver salt oxidizing agent and a reducing agent in the same system, and development by high-temperature heating. Up to now, methods for improving the occurrence of thermal fog and these heat-developable photosensitive materials have been proposed.
For example, there can be mentioned a method using a mercury compound and a heat-developable photosensitive material using the method described in Japanese Patent Publication No. 11113/1983. However, while it is known that the above-mentioned mercury compounds are effective in improving thermal fog, it is known that such mercury compounds are harmful in practice and may also cause pollution. It is being In addition, methods using organic compounds that are not harmful as described above and heat-developable photosensitive materials have been proposed. For example, a method using a thiouracil derivative and a heat-developable photosensitive material thereof described in JP-A-51-3223 can be mentioned. However, the method using the above-mentioned thiouracil derivative cannot sufficiently suppress thermal fog during heat development compared to the case where a mercury compound is used, and satisfactory results have not been obtained. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a heat-developable photosensitive material having an effect comparable to that of heat-developable photosensitive materials containing heavy metal salts such as mercury compounds in suppressing thermal fog. Another object of the present invention is to provide a heat-developable photosensitive material that has high image density and can form pure black images. Such an object of the present invention is to provide at least
(a) an oxidation-reduction image forming component consisting of a reducible organic silver salt and a reducing agent, (b) a photosensitive silver halide or (and) a photosensitive silver halide forming component, and (c) a heat developable image forming component consisting of a binder. In a heat-developable photosensitive material in which an optical element is formed in a single layer or in multiple layers, the heat-developable photosensitive element comprises (d) a disulfide compound represented by the following general formulas (A), (B), and (C). This can be achieved by using a heat-developable photosensitive material containing at least one type of photosensitive material. General formula (A) In the formula, R ₁ and R ₂ are hydrogen atoms, alkyl groups (e.g., methyl, ethyl, propyl, butal, t-butyl, pentyl, etc. having 1 to 5 carbon atoms)
alkyl groups), phenyl groups, alkoxycarbonyl groups (e.g., methoxycarbonyl groups, ethoxycarbonyl groups, propoxycarbonyl groups,
-Alkoxycarbonyl group having an alkoxy group having 1 to 8 carbon atoms such as ethylhexyloxycarbonyl group, acyl group (e.g. acetyl group, benzoyl group, propanoyl group, butanoyl group, 2-
(ethylhexanoyl group, naphthoyl group, furoyl group, etc.), and R ₁ and R ₂ may be condensed to form a benzene ring or naphthalene ring which may be substituted with a halogen atom. General formula (B) In the formula, R ₃ is an alkyl group (for example, an alkyl group having 1 to 5 carbon atoms such as a methyl group, ethyl group, or propyl group), a substituted or unsubstituted phenyl group (for example,
represents a phenyl group which may be substituted with a chlorine atom, a bromine atom, a methyl group, a methoxy group, a nitro group, a cyano group, etc. General formula (C) In the formula, R ₄ and R ₅ are alkyl groups (e.g., methyl group,
Ethyl group, propyl group, butyl group, pentyl group,
hexyl group, etc.), substituted or unsubstituted phenyl group (for example, phenyl group, or phenyl group substituted with methyl group, ethyl group, methoxy group, halogen atom, nitro group, cyano group, etc.). Specific disulfide compounds of the present invention described above are listed below. The disulfide compounds of the present invention can be easily produced by known methods. The method and timing of addition of the compounds represented by general formulas (A), (B), and (C) used in the present invention are not particularly limited, and the compounds represented by the general formulas (A), (B), and (C) used in the present invention may be added in a state in which they are dissolved in an appropriate solvent, preferably an alcoholic solvent. or directly added to the heat-developable photosensitive coating solution, or after coating the heat-developable photosensitive coating solution on the support and drying, the surface is coated with the general formulas (A), (B) and (C). A method of adding the compound by immersion in a solution containing the compound shown can be adopted. The preferred addition amount range of the disulfide compound of the present invention is 0.0001 mol per mole of the reducible organic silver salt.
mol ~ 0.1 mol, preferably 0.005 mol ~
It is 0.05 mole. Further, as shown in the Examples below, when the disulfide compound of the present invention is used in combination with a very small amount of a mercury compound, it exhibits a synergistic thermal fog prevention effect, and the amount of the mercury compound added can be significantly reduced. The heat-developable photosensitive element used in the present invention contains at least an oxidation-reduction image forming component consisting of a reducible organic silver salt and a reducing agent, a photosensitive silver halide or/and a photosensitive silver halide forming component, and a binder. These substances can be contained in a single layer, but the reducing agent may be contained in a separate layer to form a multilayer, or a reducible organic silver salt or reducing agent may be added above or below the single layer. It is also possible to have a multilayer structure including a layer containing . This reducible organic silver salt is disclosed in Japanese Patent Publication No. 4924-1983 and Japanese Patent Application Publication No. 46-1989.
Silver salts of organic acids described in each publication No. 6074, or silver salts of organic compounds having an imino group or mercapto group, especially silver salts of long-chain fatty acids having 12 to 24 carbon atoms, are oxidized at room temperature and under indoor light. This is preferable because it is less susceptible to undesirable changes such as darkening. Specific examples include silver behenate, silver stearate, silver palmitate, silver myristate, silver laurate, silver oleate, and silver hydroxystearate, among which silver behenate is particularly effective. . Various reducing agents can be used in the above-mentioned oxidation-reduction image forming component. In general, developers used in ordinary silver halide photosensitive materials, specifically hydroquinone, methylhydroquinone, chlorohydroquinone, methylhydroxynaphthalene, N,N'-diethyl-p-phenylenediamine, aminophenol, Examples include ascorbic acid, 1-phenyl-3-pyrazolidone, etc. In addition to these, 2,2'-methylenebis(6-tert-butyl-4-methylphenol), 4,4'-butylidenebis(6- tert-butyl-3-methylphenol), 4,
4'-thiobis(6-tert-butyl-3-methylphenol), etc., and also bisnaphthol reducing compounds described in JP-A No. 46-6074, or 4 described in Belgian Patent No. 802519. - Sulfonamide phenol compounds such as benzenesulfonamide phenol can be mentioned. The heat-developable photosensitive element according to the present invention may contain a binder alone or in combination in the layer. Suitable materials for the binder can be hydrophobic or hydrophilic, and transparent or translucent. Specifically, polyvinyl butyral, cellulose acetate butyrate, polymethyl methacrylate, polyvinylpyrrolidone, ethyl cellulose, cellulose acetate, polyvinyl acetate, polyvinyl alcohol, gelatin, and the sulfobetaine repeating unit described in Canadian Patent No. 774054. Examples include those that have. The content of the binder is preferably in a weight ratio of 10:1 to 1:10, more preferably 2:1 to 1:4, based on the weight of the reducible organic silver salt. This heat-developable photosensitive element contains silver halides such as silver chloride, silver bromide, silver iodide, silver iodobromide, silver iodochloride, and silver iodochlorobromide to impart photosensitivity. There is a need. This silver halide is
Particularly fine particles are effective, and as a method for preparing them, part of the reducible organic silver salt is mixed with silver halide forming components such as ammonium bromide, lithium bromide, sodium chloride, N-bromosuccinimide. , etc. to prepare fine silver halide. Furthermore, a method of incorporating so-called extra-system silver halide can also be used. A heat-developable photosensitive element containing this extra-system silver halide is described, for example, in Belgian Patent No. 774,436. That is, in other words outside of the heat-developable photosensitive element, the photosensitive silver halide is prepared outside of the oxidation-reduction image-forming components, and then the silver halide is added to and mixed with the image-forming components after preparation. It is prepared by A suitable content of silver halide (or silver halide forming component) is preferably per mole of reducible organic silver salt.
0.001 mol to 0.30 mol, more preferably 0.01 mol to
It is 0.15 mole. Moreover, a suitable color toning agent can be contained.
A toning agent for this purpose is US Pat. No. 3,080,254
phthalazinone or its derivatives as described in the specification,
These include cyclic imides described in JP-A No. 46-6074, phthalazinedione compounds described in JP-A-50-32927, and the like. Other suitable additives, such as development accelerators, hardeners, antistatic agents (layers), UV absorbers, fluorescent brighteners, filter dyes (layers)
etc. can be used. Elements according to the invention may contain suitable spectral sensitizers. Useful sensitizing dyes include cyanine dyes, merocyanine dyes, and xatene dyes, especially ``Product Licensing Index''.
Vol. 92, pp. 107-110 (published December 1971) or Belgian Patent No. 772371 are useful. The heat-developable photosensitive element according to the present invention can be coated on a suitable support to obtain a heat-developable photosensitive material. Typical supports include polyethylene,
polypropylene, polyethylene terephthalate,
Synthetic resin films such as polycarbonate and cellulose acetate, synthetic paper, paper coated with resin films such as polyethylene, art paper, baryta paper for photographs, and other papers, or metal plates (foils) such as aluminum, by the usual method. Examples include a synthetic resin film, a glass plate, and a glass plate having a metal-deposited film. The present invention will be described below with reference to Examples, but the present invention is of course not limited to these. Example 1 Silver behenate 25g, behenic acid 20g, xylene 325
ml and 325 ml of n-butanol were dispersed using a homomixer to prepare a dispersion. 40 g of polyvinyl butyral was added to this dispersion and dissolved with stirring.
Thereafter, the temperature was adjusted to 50°C, and 0.25 g of lithium bromide dissolved in 50 ml of methanol was added, and stirring was continued for 2 hours. After that, the temperature was adjusted to 30°C to prepare a first coating solution. The first coating liquid thus prepared was applied onto photographic base paper using a roll coater. The amount of application when drying is
It was 7.0g/ ^m2 . Next, on top of the film formed by applying the above first coating solution, a second coating solution consisting of the following components is overcoated using a roll coater so that the dry coating amount is 5.0 g/ ^m2 . A heat-developable photosensitive material (i) was prepared. Second coating liquid 2,2'-methylenebis-(6-t-butyl-4-
Methylphenol) 50g Phthalazinone 15g Polyvinyl butyral 40g Sensitizing dye* 0.01g Disulfide compound (1) (indicated by the disulfide compound number listed above. The same applies hereinafter) 0.14g Xylene 500ml n-butanol 500ml *Sensitizing dye; 3 -ethyl-5-[(3-methyl-
2-Thiazolinidene) ethylidene] rhodanine or the above-mentioned heat-developable photosensitive material (i) as a comparative sample
A heat-developable photosensitive material (ii) was prepared in the same manner as the heat-developable photosensitive material (i) except that the disulfide compound (1) was removed. Furthermore, instead of the disulfide compound (1), 2-
A heat-developable photosensitive material (iii) was prepared in the same manner as the heat-developable photosensitive material (i) except that 0.065 g of mercaptobenzothiazole was used. each for each sample
The light source is a 150W tungsten lamp for enlargement.
Exposure was applied at 400 lux for 10 seconds using a light wedge (Kodak Step Tablet No. 2), and heat development was performed at 115 DEG C. for 10 seconds using a heated roller to obtain the image characteristics shown in Table 1 below.

[Table] ※※Relative sensitivity indicates the relative amount of each sensitivity measured using the point of fog density + 0.1 as the reference amount (sensitivity was measured in the same way in the following examples),
The sensitivity of the photothermographic material (ii) is expressed as 100. As shown in Table 1, the heat-developable photosensitive material (i) using the disulfide compound (1) of the present invention exhibited an excellent thermal fog suppressing effect without a decrease in sensitivity. Example 2 In the description of Example 1, 0.15% of disulfide compound (8) was used instead of disulfide compound (1).
Using 0.14g of disulfide compound (9), heat-developable photosensitive material (v) was prepared.
A heat-developable photosensitive material (vi) was prepared using 0.09 g of the disulfide compound (10), and a heat-developable photosensitive material (vii) was prepared using 0.24 g of the disulfide compound (15). Exposure and heat development were carried out using the method described above, and the results shown in Table 2 below were obtained.

[Table] Example 3 In the description of Example 1, a heat-developable photosensitive material (viii) was prepared by adding 1.6 mg of mercuric acetate in addition to the disulfide compound (1). Furthermore, 1.6 mg of mercuric acetate was used instead of the disulfide compound (1), and the heat-developable photosensitive material (ix) was further replaced with mercuric acetate.
A heat-developable photosensitive material (x) was prepared using 160 mg. Exposure and heat development were performed according to the method described in Example 1, and the results shown in Table 3 below were obtained.

[Table] ※※※The sensitivity of the heat-developable photosensitive material (viii) is expressed as 100. As shown in Table 3, it was found that by using the disulfide compound of the present invention in combination with a mercury compound, the amount of the mercury compound used was significantly reduced, and a further significant fog-inhibiting effect was exhibited. Example 4 Silver behenate 25g, behenic acid 20g, xylene 325
ml and 325 ml of n-butanol were dispersed using a homomixer to prepare a dispersion. 60 g of polyvinyl butyral was added to this dispersion and dissolved with stirring. After 60℃
Heat to a controlled temperature and add 0.5 g of N-bromosuccinimide.
was added and stirring was continued for 2 hours. After that, adjust the temperature to 35℃ and
It was used as a coating liquid. The first coating solution thus prepared was applied onto photographic base paper using a roll coater. The coating amount upon drying was 0.85 g/m ² . Next, on the film formed by applying the first coating solution, a second coating solution used in preparing the heat-developable photosensitive material (i) described in Example 1 is applied by a roll coater to dry the film. A heat-developable photosensitive material (2) was prepared by repeating coating so that the coating amount was 5.0 g/m ² . When an image was formed by the method described in Example 1, a black image with a maximum density of 1.65 and a fog density of 0.10 was obtained.

Claims (1)

[Scope of Claims] 1. At least (a) an oxidation-reduction image forming component comprising a reducible organic silver salt and a reducing agent, (b) photosensitive silver halide or (and) photosensitive silver halide on a support. In a heat-developable photosensitive material in which a heat-developable photosensitive element comprising a forming component and (c) a binder is formed in a single layer or in multiple layers, the heat-developable photosensitive element has (d) the following general formulas (A) to ( A heat-developable photosensitive material comprising at least one disulfide compound represented by C). General formula (A) (However, in the formula, R ₁ and R ₂ are hydrogen atoms, alkyl groups,
It represents a phenyl group, an alkoxycarbonyl group, or an acyl group, and R ₁ and R ₂ may be condensed to form a benzene ring or a naphthalene ring which may be substituted with a halogen atom. ) General formula (B) (However, in the formula, R ₃ represents an alkyl group or a substituted or unsubstituted phenyl group.) General formula (C) (However, in the formula, R ₄ and R ₅ represent an alkyl group or a substituted or unsubstituted phenyl group.)