JPH02301746A - Silver halide photographic sensitive material for direct positive - Google Patents

Abstract

PURPOSE:To provide the prescribed max. density and contrast and to lower the min. density by adding a soluble rhodium salt and soluble iridium salt to core silver halide particles after the formation of the particles and further forming silver halide shells, then fogging the shell surfaces. CONSTITUTION:The soluble rhodium salt and soluble iridium salt are added to the silver halide particles of the silver halide photographic sensitive material having previously fogged direct positive type silver halide emulsion layers after at least one of the above-mentioned particles forms the core silver halide particles and further, the silver halide shells are formed. The shell surfaces of these silver halide particles are fogged. The low min. density is obtd. and stable gammas are exhibited in this way without decreasing the max. density as the direct positive image.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a silver halide photographic light-sensitive material, and more particularly to the improvement of photographic properties of a direct positive type silver decagenide photographic light-sensitive material which has been fogged in advance. It is something.

[Background of the invention]

Usually, when a silver halide photographic light-sensitive material is exposed to light that includes light in the photosensitive range of the light-sensitive material and developed, its blackening density increases as the exposure amount increases, and reaches a maximum value at a certain exposure amount. However, when the exposure amount is further increased, a phenomenon is observed in which the blackening density decreases. This phenomenon is called solarization. Therefore, if a silver halide photographic emulsion is optically or chemically given an appropriate amount of fog so that the blackening density reaches its maximum value, solarization will occur upon exposure and a positive image can be directly obtained. . As is well known, a light-sensitive material that utilizes such a reversal phenomenon is called a direct positive silver halide photographic light-sensitive material.

This type of direct positive silver halide photographic light-sensitive material is used for copying various types of photographs, or when used for copying relatively continuous tone photographs such as X-ray photographs.
In order to perform good copying, a direct positive type photographic light-sensitive material with soft contrast is desired, and in particular, there is a demand for the development of a light-sensitive material that can effectively reduce contrast while maintaining a predetermined maximum density and has a low minimum density.

As one of this kind of technical means, for example, US Pat.
．． As described in No. 615,573, it has been proposed to reduce the contrast by mixing monodisperse direct reversal silver halide photographic emulsions with various degrees of fog. The process for producing silver photographic emulsions is relatively complicated, and it is difficult to produce them stably and with good reproducibility. In addition, as a simple method in terms of the manufacturing process, for example, as described in U.S. Pat. A method has been proposed. However, when such a sensitizing dye is directly added to a positive-working silver halide emulsion, fog nuclei are generally easily oxidized during storage of the direct-positive silver halide light-sensitive material, resulting in a decrease in maximum density and a change in gamma over time. In addition, after photographic processing of direct positive silver halide light-sensitive materials, dyes often remain in the silver halide emulsion, causing color staining, which is an unfavorable phenomenon in terms of photographic image quality.

Furthermore, in a direct positive emulsion with heterogeneously dispersed and irregularly shaped silver halide grains and a silver iodide content of 10 mol% to 20 mol%, as shown in JP-A No. 49-91632, Processability is poor due to the high content of silver iodide, leading to poor fixation and removal, and the eluted iodide contaminates the developer, which should adversely affect the processability of other films.

Furthermore, JP-A-57-82836 discloses a method of combining separate amounts of an emulsion and a fogging agent over a long period of time, thereby continuously fogging silver halide grains to various degrees and softening the contrast. However, since this method involves complicated manufacturing steps, it is difficult to manufacture it stably and with good reproducibility.

Furthermore, Japanese Patent Application Laid-open No. 61-286953 proposes a method of adding water-soluble iodide and then plucking it in the presence of thiosulfate and/or thioanate; however, this method is also sufficiently effective. However, in particular, the reduction in minimum concentration was not satisfactory.

[Purpose of the invention]

An object of the present invention is to provide a direct positive silver halide photographic light-sensitive material that has a predetermined maximum density and contrast, has a low minimum density, and exhibits little reduction in maximum density when developed over time. .

Other purposes will become clear in the following specification.

[Structure of the invention]

As a result of intensive studies, the inventors have achieved the above-mentioned object by the present invention as described below.

In a silver halide photographic light-sensitive material having a direct positive silver halide emulsion layer that has been fogged in advance, at least one of the silver halide grains contains soluble rhodium salt and soluble iridium after forming a core silver halide grain. Add salt;
Further, after forming a silver halide shell, the surface of the shell is formed of a direct positive silver halide photographic light-sensitive material in which fogged silver halide grains are formed.

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

The silver halide emulsion used in the present invention can be prepared by a neutral method, an acid method,
Any ammonia method may be used.

Also, single jet method, double jet method, Con I ~
Although a mixing method such as a rolled double jet method can be used, a controlled double diene 1-method in which particles are grown while controlling pH, p/kg, etc. is particularly preferred.

The halogen composition of the core silver halide may be any of silver chloride, silver chlorobromide, silver bromide, silver iodobromide, and silver chloroiodobromide.

The crystal habit may be cubic, tetradecahedral, octahedral, spherical, potato-shaped, etc., and may be monodisperse or polydisperse.

The halogen composition of the shell silver halide may be silver chloride, silver chlorobromide, silver bromide, silver iodobromide, or silver chloroiodobromide, but
Silver bromide or silver iodobromide is preferred. (In the case of silver iodobromide, it is preferable that the silver iodide content is 6 mol% or less.)
The ratio of shell to core is 1 as a molar ratio:
100-io:1 preferably 1:30-5:1.

The crystal habit after the shell may be cubic, tetradecahedral, octahedral, spherical, or potato-shaped, and the grain size is 0.
It is 1 to 2.0 μm, preferably 0.15 to 1.0 μm.

Next, the soluble rhodium salt according to the present invention is preferably a rhodium halide salt or a hexahalogen rhodium complex salt, and the amount added is in the range of 0.001 to 100 mmol per mol of silver halide after shelling. is preferred.

The soluble iridium salts are preferably hexahalogen iridium complex salts, hexacyanoiridium complex salts, etc., and the amount added is preferably in the range of 0.001 to 100 mmol per mol of silver halide after shelling.

The molar ratio of rhodium salt and iridium salt is 100:1~
l:100 is preferable, and moreover ■0:1 to i:to
is within the range of

After the silver halide shell layer has been formed, the silver halide emulsion according to the present invention is given a suitable fog using a reducing agent and a gold compound for the silver halide emulsion. Either at least 17 compounds selected from thiosulfate and/or thiocyanate are allowed to coexist, or after fogging with a reducing agent and a gold compound, thiosulfate and/or thiocyanate are formed. By containing at least one compound selected from acid salts, even better fogging can be imparted.

Hydrophilic colloids other than gelatin that can be used as protective colloids in the photosensitive material of the present invention include, for example, gelatin derivatives, graft polymers of gelatin and other polymers, proteins such as albumin and casein, hydroxyethyl cellulose, carboxymethyl cellulose, etc. , cellulose derivatives such as cellulose sulfate esters, sugar derivatives such as sodium alginate, starch derivatives: polyvinyl alcohol, polyvinyl alcohol partial acetal,
Various synthetic hydrophilic polymeric materials such as mono- or copolymers of poly-N-vinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinylimidazole, polyhinylvirazole, etc.

In the case of gelatin, use the baggy method to make jelly strong 81 It is preferable to use a material with a degree of 200 or more.

In the photographic material of the present invention, it is advantageous to use gelatin as a hydrophilic colloid that can be used in photographic constituent layers such as a protective layer, banking layer, and intermediate layer, which are formed as necessary. , and other hydrophilic colloids mentioned above can also be used alone or together with gelatin.

Other photographic additives may also be added to the direct positive silver halide emulsion according to the present invention. As stabilizers, for example, those described in Japanese Patent Publication Nos. 49-16053, 49-12651, and 48-66828, triazoles, azaindenes, benzothiazolium compounds, mercapto compounds, or cadmium and cobalt. , nickel, manganese, zinc, and other water-soluble inorganic salts. Hardeners such as formalin, glyoxal, aldehydes such as mucochloric acid, S-triazines, epoxies, aziridines, vinylsulfonic acid, etc.; coating aids such as saponin, sodium polyalkylene sulfonate of alkylphenol, polyethylene. Lauryl or oleyl monoether of glycol, aminated alkyl taurine, JP-A-49-10722,
Fluorine-containing compounds selected from those described in Japanese Patent Publication No. 49-46733, etc., and sensitizers such as
No. 25203, No. 43-1.0245, No. 43-13
No. 822, No. 43-17926, No. 43-17927
No. 46-21186, No. 49-8102, No. 4
It may also contain polyalkylene oxides and derivatives thereof selected from those described in No. 9-8332 and the like.

Further examples are Special Publication No. 45-249 IO and No. 45-298.
It is also possible to contain color couplers selected from those described in No. 78 and the like. In addition, brighteners, thickeners, preservatives, matting agents, antistatic agents, etc. can also be added as necessary.

Also, from the top of emulsion technology, Japanese Patent Publication No. 44-2523, No. 44-
As described in No. 9499, the developer is protected and contained, higher fatty acids such as liquid paraffin and higher unsaturated fatty acids such as stearyl acetate and glyceride are added to protect the film to improve the physical properties of the film, and color additives are added depending on the purpose. It is also possible to contain protectors such as couplers and stabilizers.

The direct positive silver halide emulsion thus obtained can be applied to any suitable photographic support such as glass, wood, metal, film, e.g. cellulose acetate-1, cellulose acetate butyrate, cellulose nitrate, polyester, polyamide. , polystyrene, etc., paper, baryta-coated paper, polyolefin-coated paper such as polyethylene or polypropylene-coated paper, etc., and the polyolefin-coated paper can be subjected to electron bombardment treatment to improve the adhesion of the emulsion.

〔Example〕

Examples of the present invention will be described in detail below. Note that, as a matter of course, the present invention is not limited to the embodiments described below.

Example Preparation of seed crystal A 60° OpAg = 8.0, pH = 2.0 controlled, a cube of silver iodobromide containing 2 mol % of silver iodide with an average grain size of 0.20 μm was prepared by the double jet method. Crystal particles were prepared.

Gelatin in which 90% of Ami7 groups are condensed with phenylcarbonyl groups is added to the mixed solution, stirred for 3 minutes, and then 0.13 g of potassium hydroxide/1 mol of AgX is added L pH
I changed it to 4.0. After standing still and decanting, 2.1 f2/AgX 1 mol of pure water at 40°C and 0.25 g/AgX 1 mol of potassium hydroxide were added to adjust the pH.
5.8i: L Stir for 5 minutes. Then nitric acid (1,
Add 1.5 mff/1 mole of AgX (7N) to pH = 4.
．． Set it to 3 and leave it still. Decanted. Furthermore, add gelatin and potassium hydroxide 0.2g/AgX 1mol and adjust the pH.
was adjusted to 5.8 and redispersed to obtain seed crystal A.

Growth from seed crystal A-1 Dissolve the above seed crystal in a gelatin solution kept at 40°C,
Furthermore, ammonia was added to adjust the pH to -8.0.

Rhodium trichloride and potassium hexachloroiridate were added to this solution as shown in Table 1, and 2 minutes later, a 1N ammoniacal silver nitrate aqueous solution and a 1N potassium bromide aqueous solution were added by a double jet method. pH during mixing is 8.0, EA
g was controlled to the values shown in Table 1.

After the mixing was completed, the pH was lowered to 6.0 with acetic acid. after that.

Desalting was carried out in the same manner as for the seed crystals, and emulsions No. 091 to No.
-13 was obtained.

Growth from Seed Crystal A-2 Emulsion No. 14 was grown in exactly the same manner as in Growth from Seed Crystal-1 except that a mixed aqueous solution of 1N potassium iodide and potassium bromide was used instead of the 1N aqueous solution of potassium bromide. ~2
I got 3. The silver iodide content after shell formation is as shown in Table 1.

Preparation of seed crystals BSC, D Seed crystals B (particle size 0.15 μm) and C (particle size 0.2
5 μm) and D (particle size 0.30 pm).

Growth from seed crystals B, C, and D Growth from seed crystal A was performed in the same manner as in I, and emulsion NO,2' with a finished grain size of 0.40 μm was grown from each seed crystal.
4-26 was obtained.

(Preparation of comparative emulsion-1) Gelatin 25g (a) Potassium iodide 8g water
1000mff
Silver nitrate 170g (b) Ammonia water equivalent water
300mff Potassium bromide 117g (c) Rhodium trichloride 42mg Water
500m1
2(d)acetic acid Amount to neutralize to pH 6.5 First, 40
At °C, add solution (b) to solution (a) and continue stirring.
(c) The solution was added over 20 minutes. After aging for 30 minutes, solution (2) was added to neutralize the mixture to pH 6.5.

(Preparation of Comparative Emulsion-2) 500 mQ of 4% gelatin solution was stirred at 65°C, 5 mff of 1% rhodium trichloride was added, and then 2000 m4 of 0.5N silver nitrate solution and 1960 m4 of 0.5N potassium bromide solution were added. 0.5N nonolium iodide solution 40mf
A mixed solution of f was added for 100 minutes, and the average particle size was 0.4 μm.
A cubic silver iodobromide emulsion was obtained.

Comparative Emulsion 1.2 above was also desalted in the same manner as Seed Crystal A.

Each emulsion obtained as above was adjusted to pH 6.8.
0 thiourea dioxide per mole of AgX at 0°C
3 mg of sulfur thiosulfate, 1.2 mg of sulfuric acid, and 1.5 mg of chloroauric acid were added, and the mixture was aged until proper fogging was obtained.

A spreading agent, hardener, wetting agent, thickener, stabilizer, etc. were added to each emulsion to prepare a coating emulsion. In addition, a nonionic surfactant was added to the gelatin solution as a protective film solution, and a spreading agent, a hardening agent, and a silica-based matting agent were further added.

A sample was prepared by simultaneously coating these solutions in multiple layers on a polyethylene terephthalate base coated with an undercoat layer and drying.

The coating amount per square meter was 3 g in terms of silver. The samples thus obtained were subjected to natural aging and forced deterioration treatment (50°, 080% RH for 3 days), and then exposed to light using an optical wedge. ], processing was performed for 90 seconds with New XD90 developer and New XF fixer (both manufactured by Konica Corp.), and the sensitivity of each sample was determined.

The sensitivity was determined by the reciprocal of the amount of light required for the blackening density to increase by 1.0, and was expressed as relative sensitivity with the sensitivity of comparative sample No. 1 in Table 1 set as 100.

=161 [Effects of the Invention] According to the present invention, a silver halide photographic light-sensitive material which has a low minimum density and stable gamma without reducing the maximum density as a direct positive image was obtained.

Furthermore, it had photographic characteristics with little change over time.

Claims (1)

[Claims] In a silver halide photographic light-sensitive material having a direct positive silver halide emulsion layer that has been fogged in advance, at least one of the silver halide grains contains soluble rhodium salt and soluble iridium after forming a core silver halide grain. Add salt;
Further, a silver halide photographic material for direct positive use is characterized in that after a silver halide shell is formed, the surface of the shell is a fogged silver halide grain.