JPH0222936B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a silver halide photographic material, and particularly to a direct positive silver halide photographic material. When a silver halide photographic light-sensitive material is exposed to light containing light in the wavelength range to which the light-sensitive material is sensitive and developed, the blackening density increases as the exposure amount increases and reaches a maximum value. If the exposure amount is further increased, the blackening density decreases again and a positive image is finally formed. Such a phenomenon is generally called solarization. A similar reversal phenomenon is also observed when exposed to light in silver halide that has been optically or chemically fogged during the production process of silver halide emulsions. The direct positive silver halide photographic emulsion of the present invention is the latter of these, that is, it has been fogged with light or chemically in advance, and is processed to form a positive image after normal exposure to light and normal development. emulsion. Conventionally, with pre-fogged direct positive silver halide photographic emulsions, a sufficiently low minimum density cannot be obtained (that is, pure white areas cannot be obtained), and the contrast of the image deteriorates, making it impossible to achieve satisfactory image quality. This defect often occurred. Desensitizing compounds are used to reduce the minimum density, but conventional desensitizing compounds often reduce the maximum density as well as the minimum density, resulting in a decrease in contrast, This often causes undesirable phenomena in terms of image quality. Particularly in the field of graphic arts where high contrast is required, there has been a strong desire to develop photosensitive materials that can reduce the minimum density for reversal without reducing contrast. It is therefore an object of the present invention to provide a direct reversal silver halide photographic material with reduced minimum density without reducing contrast. The object of the present invention was achieved by combining at least one phenazine compound represented by the following general formula (), (), or () with a nitroindazole compound represented by the general formula (). . Considering that nitroindazole compounds alone have almost no effect on the minimum density of direct positive emulsions, the combination of phenazine compounds and nitroindazole compounds significantly reduces the minimum density of reversal in direct positive silver halide emulsions. is an unexpected effect. In the formula, R ₁ to _{R 4} may be the same or different, and each represents a hydrogen atom, an alkyl group (preferably a C ₁ to C ₄ group, such as methyl, ethyl, propyl, butyl, t-butyl, etc.), Aryl groups (preferably C ₆ to _{C 10} such as phenyl, naphthyl, tolyl, etc.), halogen atoms (chloro,
bromo, iodo, etc.) alkoxyl groups (preferably _C1 - _C4 , e.g. methoxy, ethoxy, etc.), hydroxyl groups, acylamino groups (preferably _C1 - _C4 , e.g. formylamino, acetamino, etc.), carboxyl group, a nitro group or a cyclic hydrocarbon group fused to a benzene ring (e.g.

[Formula], etc.). Among these, a hydrogen atom, an alkyl group, a halogen atom, an alkoxyl group, a nitro group, and a hydroxyl group are preferred, and a hydrogen atom, an alkyl group, and an alkoxyl group are particularly preferred. Also, m, n, p, and q are each 1, 2, or 3.
represents. Specific examples are given below, but the invention is not limited thereto. Compound of general formula () Compound of general formula () Compound of general formula () The compounds represented by the general formulas () to () are known and can be easily obtained or synthesized (see, for example, Japanese Patent Publication No. 47-8746). At least one compound represented by the general formula (), () or () is preferably used in an amount of 5 mg to 500 mg, particularly 20 mg to 200 mg, per mole of silver halide. Next, the compound represented by the general formula () will be explained. In the formula, R represents a hydrogen atom or an alkyl group (preferably a _C1 to _C5 group, such as methyl, ethyl, propyl, t-butyl, pentyl, etc.).
It is assumed that NO ₂ is substituted at the 5th, 6th or 7th position. in particular Examples include, but are not limited to, the following. Compounds of general formula () are also known and can be easily obtained or synthesized. The compound of the general formula () is preferably used in combination with at least one compound represented by the general formula (), () or () in a range of 10 mg to 500 mg per mole of silver halide. At least one of the compounds represented by the above general formula (), () or () of the present invention and the compound represented by the general formula () are dissolved in water or a preferably low-boiling organic solvent miscible with water, It is added to the emulsion at an appropriate time after desalting and before coating, preferably after fogging. Instead of being added to the emulsion, a portion may be added to a non-photosensitive hydrophilic colloid layer, such as a protective layer. In the fog-added direct reversal silver halide emulsion of the present invention, silver halides such as silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, and silver iodobromide emulsions are dispersed in the protective colloid layer described below. These emulsions can be prepared by various methods such as neutral method, ammonia method, acid method, or method using thioether solvent as described in U.S. Pat. No. 3,574,628.
Manufactured by various methods. The raw emulsions used in the direct positive silver halide photosensitive materials used in the present invention are classified into the following two types. One of the raw emulsions has a nucleus capable of trapping free electrons inside the silver halide. It is an emulsion whose surface is fogged with light or chemically. The feature of this type of raw emulsion is that it directly gives a positive image by itself, and by adding a sensitizing dye, it can not only increase the sensitivity through spectral sensitization but also sensitize the intrinsic absorption region. can give. Group metal salts are preferably used to form the free electron trap nuclei in this type of raw emulsion. Another raw emulsion is an emulsion in which the surface of silver halide is chemically covered without providing free electron trap nuclei inside the silver halide. This raw emulsion does not give any direct positive image by itself, but it gives a direct positive image by using an organic desensitizer. For raw emulsions with electron trap nuclei, see Tokkosho.
No. 43-4125, Special Publication No. 43-29405, U.S. Patent No.
No. 2401051, No. 2976149, No. 3023102, British Patent No. 707704, No. 1097999, French Patent No.
No. 1520824, No. 1520817, Belgian patent no.
It is described in No. 713272, No. 721567, and No. 681768. British Patent Nos. 1186717 and 1186714 regarding raw emulsions and organic desensitizers that do not have electron trap nuclei.
No. 1186716, No. 1520817, U.S. Patent No.
It is described in No. 3501306, No. 3501307, No. 3501310, No. 353128, etc. In the present invention, either raw emulsion classified into the above two categories can be used. The silver halide photographic emulsion used in the present invention is
As mentioned above, it is fogged with light or chemically in advance. Chemical fogging agents such as hydrazine derivatives, thiourea dioxide, formalin, amine borane, and stannous chloride can be used. The emulsion can also be fogged with metals that are more electrically positive than silver, such as rhodium, gold, platinum, iridium, and the like. The degree of fogging of direct reversal silver halide emulsions can be varied over a wide range, depending on the silver halide composition used,
The type of fogging agent used including the particle size,
concentration, pH of the emulsion at the time of fogging,
Related to pAg, temperature, time, etc. When implementing fogging, U.S. Patent No. 3867149, U.S. Patent No. 3062652,
You can refer to the descriptions of US reissued patents Re29930, Re29974, etc. Various compounds known as photographic additives, such as those described in Research Disclosure, Vol. 176, pages 22-31 (November 1979 issue), can be added to the silver halide photographic emulsion used in the present invention.
Stabilizers include, for example, mercapto compounds, tetrazaindene compounds, hardeners include aldehyde compounds, 2-hydroxy-
4,6-dichloro-1,3,5-triazine compounds, N-methylol compounds, vinyl sulfone compounds, etc. As coating aids, natural surfactants such as saponin, nonions such as alkylene oxides, glycidols, etc. Surfactants, anionic surfactants containing acidic groups such as carboxylic acids, sulfonic acids, phosphoric acids, sulfuric acid ester groups, and phosphoric ester groups, amphoteric surfactants such as amino acids, aminosulfonic acids, and leg-cleavers for lithographic development. A polyalkylene oxide compound which also acts as a polyalkylene oxide compound can be included. Further, for the purpose of improving dimensional stability, etc., a dispersion of a water-insoluble or sparingly soluble synthetic polymer can be included. For example, alkyl (meth)acrylate, alkoxyalkyl (meth)
Acrylates, (meth)acrylamides, vinyl esters (e.g. vinyl acetate), acrylonitrile, etc. can be used alone or in combination; specific examples thereof include U.S. Pat.
No. 2739137, No. 3411911, No. 3488708, No.
It is described in No. 3607290, No. 3635715, etc. The emulsion used in the present invention mainly uses gelatin as a protective colloid, and it is particularly advantageous to use inert gelatin for photographic properties. ), water-soluble synthetic polymers such as polyvinyl acrylate, polyvinyl alcohol, polyvinylpyrrolidone, etc. may be used. The emulsions of the present invention can be applied to any suitable photographic support,
For example, a positive silver halide photographic light-sensitive material is produced directly by coating glass, a film base (eg, cellulose acetate, cellulose acetate butyrate polyester, eg, poly(ethylene terephthalate)), or the like. The preferred amount of coated silver is in the range of 1 g/m ² to 6 g/m ² . Exposure to obtain a reversed image may be performed using a conventional method. That is, any of a variety of known light sources such as a tungsten electric lamp, a mercury lamp, a xenon arc lamp, a xenon flash lamp, etc. can be used. The direct positive silver halide light-sensitive material of the present invention may be subjected to the usual development process described in the aforementioned Research Disclosure Magazine, but the so-called ``Lith type'' development process (``Lith type'' development process) may be applied. Processing is a process in which dihydroxybenzenes are usually used as a developing agent and the development process is carried out contagiously under low sulfite ion concentrations for photographic reproduction of line images or halftone images. development process) and JP-A-54-37732,
It is possible to apply the so-called "ultra-high contrast" development treatment described in US Pat. No. 4,221,857 and other specifications in which development is performed in the presence of a hydrazide compound. Examples of the present invention will be shown below to further specifically explain the present invention. Example An aqueous solution of potassium bromide and an aqueous solution of silver nitrate were simultaneously added to an aqueous gelatin solution at 65° C. for about 60 minutes under stirring to prepare a silver bromide gelatin emulsion with an average grain diameter of about 0.2 μm. This emulsion was desalted by a flocculation method using a polyanionic polymer and adjusted to pH = 10 to yield 25mg per mole of silver.
of hydrazine was added and heated at 65°C for 70 minutes to give a fog. This emulsion was then divided into several equal parts, each containing 500 mg of 6-ethoxy-1-methyl-2-(3-nitrostyryl) per mole of Ag as the electron acceptor.
Quinolinium methyl sulfate was added, and a phenazine compound and a nitroindazole compound of the present invention were dissolved in methanol and added as shown in Table 1, respectively. Samples 1 to 9 were coated with each emulsion on a separate cellulose triacetate film at a silver content of 3 g/m ² . The coated sample was exposed to light through a light wedge using an Hg lamp light source, developed with a developer having the following formulation for 3 minutes at 20°C, and fixed to obtain strips. The density of this was measured using a P-type densitometer manufactured by Fuji Photo Film Co., Ltd., and a characteristic curve was obtained. The formulation and sensitometry results are shown in Table 1. In addition, to show an example of using a type of emulsion that has free electron trap nuclei inside the grains, an aqueous solution of potassium bromide and an aqueous solution of silver nitrate were added to an aqueous gelatin solution in the presence of a rhodium salt while stirring at 65°C. It takes about 60 minutes to add the particles, and the average particle diameter is about 0.2μ.
Make silver bromide and give it a fog in the same way as above,
Next, this emulsion was divided into several equal parts, the phenazine compound and the nitrointazolic compound of the present invention dissolved in methanol were added to each part as shown in Table 1, and 3 g/m of silver was added to each separate cellulose triacetate film. Samples ¹⁰ to 18
I got it. The coated sample was exposed to light using a mercury lamp light source through a light wedge, developed and fixed, and the density was measured. Table 1 shows the results. Composition of developer Metol 3.1g Sodium sulfite 45g Hydroquinone 12g Sodium carbonate 79g KBr 1.9g H ₂ O 1

[Table] Samples of the present invention using a combination of phenazine compounds and nitroindazole compounds as shown in Table 1
It can be seen that Nos. 4, 5, 8, 9, 13, 14, 17, and 18 have significantly lower minimum concentrations than Comparative Examples 2, 3, 6, 7, and 11, 12, 15, and 16.

Claims (1)

[Claims] 1. A compound characterized by containing at least one compound selected from the compounds represented by the following general formula (), (), or () and a compound represented by the general formula (). A direct positive silver halide photographic light-sensitive material. In the formula, R ₁ to _{R 4} may be the same or different and each represents a hydrogen atom, an alkyl group, an aryl group,
Represents a cyclic hydrocarbon fused to a halogen atom, alkoxyl group, hydroxyl group, acylamino group, carboxyl group, nitro group, or benzene ring. m, n, q, p represent 1, 2 or 3. In the formula, R is a hydrogen atom, an alkyl group (having 1 to 1 carbon atoms)
5), and NO ₂ is substituted at the 5th, 6th or 7th position.