JPH02179635A - Direct positive silver halide photographic sensitive material having high sensitivity - Google Patents

Abstract

PURPOSE:To obtain a direct positive silver halide photographic sensitive material having elevated sensitivity and increased maximum density and reduced fog by incorporating an emulsion prepd. by adding fine silver iodide particles and dissolving the particles before completion of growth of silver halide particles. CONSTITUTION:An emulsion contg. dissolved body is formed by adding and dissolving fine silver iodide particles before completion of silver halide particles and physical-ripening into >= one direct positive silver halide emulsion layer of the sensitive material. The direct positive emulsion is formed by generating fogs with a reducing agent and an Au compd., etc. A protective colloid such as gelatin and a binder for an emulsion such as polymer latex may be used in combination.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a silver halide photographic material, and particularly to a highly sensitive direct positive silver halide light-sensitive material.

[Conventional technology]

Normally, when a silver halide photographic light-sensitive material is exposed to light including light in the photosensitive range of the light-sensitive material and developed, the blackening density increases as the exposure amount increases, and reaches a maximum 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 reversal silver halide photographic light-sensitive material.

This type of direct reversal silver halide photographic light-sensitive material is used for copying various types of photographs, but when used for copying photographs with relatively continuous gradation such as X-ray photographs, it is important to obtain good reproduction. For this purpose, a soft direct reversal photographic material is desired. In particular, there is a need to develop a photosensitive material that maintains a predetermined maximum density, has high sensitivity, has little reversal fog, and has good storage stability over time.

According to conventional technical means, ammoniacal silver iodobromide emulsions are usually suitable as direct positive silver halide emulsions used in this type of light-sensitive materials because of their relatively high sensitivity. In some cases, only a high minimum concentration can be obtained.

In addition, as a simple method in terms of manufacturing process, for example, U.S. Patent No. 3,
As described in No. 364.026, a method has been proposed to reduce the contrast by adding merocyanine dyes of the sensitizing dye type directly to the reversal silver halide emulsion. However, when such a sensitizing dye is added to a direct reversal silver halide emulsion, fog nuclei are generally easily oxidized during storage of the direct reversal silver halide light-sensitive material, resulting in a decrease in maximum density and a change in gamma over time. Furthermore, after photographic processing of a direct reversal silver halide light-sensitive material, dyes often remain in the silver halide emulsion, resulting in color staining, which is an unfavorable phenomenon in terms of photographic image quality.

In addition, as shown in JP-A No. 49-91632, a direct positive emulsion with heterogeneously dispersed and irregularly shaped silver halide grains and a silver iodide content of 10 mol % to 20 mol % is used. The technology used has drawbacks such as poor processability due to the high content of silver iodide, which leads to poor fixation, and eluted iodide contaminates the developer, adversely affecting the processability of other photosensitive materials. be.

As mentioned above, conventional direct positive silver halide photographic materials have problems such as soft contrast, maximum density, sensitivity, reversal fog, and
In terms of storage stability over time, trying to satisfy these requirements would have other negative effects, and in the end, with conventional technology, the maximum concentration,
Only products with low sensitivity, high reversal fog, and poor storage stability over time were obtained.

[Purpose of the invention]

The present invention has been made in view of the problems of the prior art described above, and an object of the present invention is to have a predetermined maximum density, sensitivity, and low fog, and to reduce the maximum density when developed by storage over time. It is an object of the present invention to provide a direct positive silver halide photographic material with a small amount of direct positive light.

[Structure of the invention]

The above-mentioned object of the present invention is to provide a direct-positive silver halide photographic light-sensitive material having at least one direct-positive silver halide emulsion layer on at least one surface of a support. Adding silver iodide fine grains to at least one layer before the end of silver halide grain growth;
A direct-positive silver halide photographic light-sensitive material characterized by containing a dissolved direct-positive silver halide emulsion,
achieved.

The present invention will be explained in more detail below.

The light-sensitive material of the present invention has at least an IN direct positive silver halide emulsion layer, and the emulsion layer constitutes at least one layer of the light-sensitive layer. Silver halide grains contained in the silver emulsion layer are optional. Preferably, the silver halide grains contain silver iodide. The shape/crystal form of the particles is arbitrary, and may have a regular crystal system such as a cube, octahedron, or tetradecahedron, or may have a crystal system such as a tabular shape or a potato shape.

The silver halide photosensitive emulsion used in the silver halide photographic light-sensitive material of the present invention may be a polydisperse emulsion or a monodisperse emulsion, or may be a monodisperse emulsion alone or a mixture of at least two types. good.

In addition, in the present invention, in order to obtain a good positive image,
Any suitable electron trap can be used. This is effective in preventing reactions in which silver nuclei form and grow between photoelectrons and silver ions. As specific means, noble metal atoms or the like may be introduced as an inorganic desensitizer into the crystal interior of the silver halide grains, or an electron-capture desensitizing dye that is adsorbed on the crystal surface may be used.

When an inorganic desensitizer is used, a soluble metal salt of group (I), such as a soluble rhodium salt or a soluble iridium salt, may be added in order to incorporate the inorganic desensitizer into the silver halide grains. These soluble salts are preferably added in an amount of 10'' to 10-z mol, more preferably 10-' to 10-3 mol, per 1 mol of gffl halide, and this is added in an aqueous solution at the time of preparing silver halide grains. It is desirable to add it to the emulsion as a compound.

For techniques using electron-capture desensitizing dyes, see
British Patent No. 1186717, British Patent No. 1186714,
U.S. Patent No. 1186716, U.S. Patent No. 1520817, U.S. Patent No. 3501306, U.S. Patent No. 3501307, U.S. Patent No. 3
It is described in No. 501310, No. 3531288, etc.

The direct positive silver halide emulsion used in the present invention can be formed by imparting appropriate fog.

For example, fog can be imparted to a silver halide emulsion by using a reducing agent and a gold compound. In this case, at least one compound selected from thiosulfate and/or thiocyanate is allowed to coexist and then fogged, or after fogging is performed with a reducing agent and a gold compound, thiosulfate is Even better fogging can be imparted by containing at least one compound selected from thiocyanates and/or thiocyanates.

Regarding the direct positive silver halide emulsion used in the present invention,
By adding water-soluble iodide to the silver halide emulsion before fogging, good release can be obtained. Examples of water-soluble iodides include ammonium, potassium, lithium, and sodium iodides, and the amount added is preferably 1 water-soluble iodide per mol of silver halide.
~10 mmol. If the amount added is less than this, the removal may not be sufficient. If the amount is more than this, a sufficient maximum concentration may not be obtained or the concentration tends to decrease during storage.

Although the conditions for fogging silver halide can be varied over a wide range, the pH is generally preferably within the range of 5.5 to 9, more preferably within the range of pH 6 to 7. Also, PAg is
Generally preferred is within the range of 6.5 to 8.5, and the temperature is generally preferably 40"C to 100"C, more preferably 5
It is in the range of 0°C to 70°C.

A hydrophilic protective colloid such as gelatin that suspends the silver halide grains during fogging is a halogenated! ! It is preferably used in a proportion of 30 to 200 grams per mole.

Reducing agents used to impart fog include aldehyde compounds such as formalin, organic reducing agents such as organic amine compounds such as hydrazine, triethylenetetramine, thiourea dioxide, and imino-amino-methanesulfinic acid, and dichloromethane. Inorganic reducing agents such as tin or reducing agents such as amine borane are preferably used.

The concentration of the reducing agent used varies depending on the silver halide grains, field of application, purpose, etc., and also varies depending on the type of reducing agent, but generally it is o, oot per mole of silver halide.
The range is preferably from 1.00 mmol to 1.00 mmol.

The gold compounds used to impart fog are generally monovalent and trivalent soluble gold salts, such as chloroauric acid, gold thiocyanate, sodium chloroaurate, potassium chloroaurate, potassium bromoaurate, iodo Potassium gold acid, potassium gold cyanide, potassium gold thiocyanide, sodium gold thiomaleate, gold thioglucose, etc. are used.

The amount of gold compound used depends on the size, composition, and
Although it varies depending on the purpose of application, it is generally preferably within the range of o,ooot to 0.1 mmol per mole of silver halide, more preferably from 0.005 to 0.0 mmol.
Good results are obtained when used at low concentrations, in the range of 5 mmol.

Further, when thiosulfate or thiocyanate is used for fogging, specific examples thereof include sodium thiosulfate, ammonium thiosulfate, potassium thiocyanate, ammonium thiocyanate, or complex salts thereof. The compound is generally used preferably in an amount of 0.0003 to 10.0 mmol, more preferably 0.005 to 0.0 mmol per mol of silver halide.
Used at 5 mmol. These thiosulfate and thiocyanate salts may be used before fogging with the reducing agent and gold, during fogging, or after fogging, but the required amount will vary depending on the time of use. Increasing amounts are generally required, especially when added after fog formation.

In the light-sensitive material of the present invention, at least one of the direct positive silver halide emulsion layers contains a direct positive silver halide emulsion to which silver iodide fine grains are added and dissolved before the silver halide grain growth is completed. do.

The period until the end of silver halide grain growth generally means (in solution)
It refers to the formation of silver halide grains by means such as double decomposition of a soluble root salt and a soluble halide in an aqueous gelatin solution (usually in an aqueous gelatin solution), and until the physical ripening is completed.

As such silver iodide grains, it is preferable to use silver iodide fine grains separately produced in advance.

Here, the silver iodide fine grains separately produced in advance are silver halide-forming elements supplied to form and prepare direct positive silver halide grains in a seed emulsion and a direct positive silver halide emulsion, that is, a soluble root salt. Silver iodide grains (-silver nitrate for boat fishing) and silver iodide grains produced from a soluble halide solution, or silver iodide grains formed too quickly, refer to other silver iodide grains.

Further, the silver iodide fine grains preferably have an average grain size smaller than that of the emulsion that directly forms the positive silver halide emulsion, and are grains substantially composed of silver iodide. The average particle size of the silver iodide fine particles used is preferably 0.7 μm or less, more preferably 0.3 to 0.005 μm, and still more preferably 0.1 to 0.01 μm.

In carrying out the present invention, the silver iodide fine grains used are preferably used in the form of a monodispersed emulsion (emulsion with a small grain size distribution).

In the present invention, when referring to dissolving silver iodide fine particles, the term "dissolution" refers to the formation of a homogeneous phase mixture of silver iodide fine particles, that is, the phenomenon of forming a so-called solution.

Various other photographic additives can be added to the direct positive silver halide emulsion used in the present invention.

As a stabilizer, for example, Japanese Patent Publication No. 49-16053, No. 49
-12651, those described in JP-A-48-66828, etc., or triazoles, azaindenes,
A quaternary benzothiazolium compound, a mercapto compound, or a water-soluble inorganic salt such as cadmium, cobalt, nickel, manganese, zinc, etc. may be included. Further, hardening agents such as formalin, glyoxal, aldehydes such as mucochloric acid, S-triazines, epoxies, aziridines, vinyl sulfonic acid, etc., and coating aids such as saponin, sodium polyalkylene sulfonate, polyethylene glycol, etc. lauryl or oleyl monoether, aminated alkyl taurine, JP-A-49-
Fluorine-containing compounds selected from those described in Japanese Patent Publications No. 42-25203, Japanese Patent Publication No. 43-10245, etc. as aggravating agents, etc.
No. 43-13822, No. 43-17926, No. 43
-17927, 46-21186, 49-81
Polyalkylene oxides selected from those described in No. 02, No. 49-8332, and derivatives thereof may also be contained. Furthermore, it is also possible to contain a color coupler selected from those described in, for example, Japanese Patent Publication Nos. 45-24910 and 45-29878. In addition, brighteners, thickeners, preservatives, matting agents, antistatic agents, etc. can also be contained as necessary.

The silver halide emulsion used in the present invention includes protective colloids such as gelatin, gelatin derivatives, and natural substances such as albumin, agar, gum arabic, and algiic acid.
Furthermore, polyvinyl alcohol, polyvinyl acrylate,
Polyvinylpyrrolidone, cellulose ethers, partially hydrolyzed cellulose acetate, Japanese Patent Publication No. 49-20530
Poly(N-
Hydrophilic polymers such as (hydroxylalkyl) β-alanine derivatives can be included. Furthermore, a dispersion polymerized vinyl compound may also be contained as a binder for emulsion. For example, using a polymer latex of an unsaturated ethylenically monomer emulsion polymerized in the presence of an activator as described in Japanese Patent Publication No. 49-32344, and a ceric salt described in Japanese Patent Publication No. 49-20964, hydroxyl groups can be removed. It is also preferable from the viewpoint of improving the physical properties of the film to contain a polymer latex, etc., which is obtained by grafting a high molecular compound with an unsaturated ethylenic monomer.

Also, from the 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 acetoglyceride are protected and contained to improve film properties, and color couplers are added depending on the purpose. It is also possible to protect and contain stabilizers and the like.

The direct positive silver halide emulsion thus obtained is
Any suitable photographic support such as glass, wood, metal,
A film, such as cellulose acetate, cellulose acetate butyrate, cellulose nitrate, polyester, polyamide, polystyrene, etc., is coated on paper, baryta-coated paper, such as polyethylene or polypropylene-coated paper, to form a photosensitive material. Polyolefin coated paper can be made to have good emulsion adhesion by electron impact treatment.

The direct positive silver halide photosensitive material constructed in this manner maintains a predetermined maximum density and altitude, exhibits little reversal fog, and has good storage stability over time.

〔Example〕

The present invention will be explained in more detail below by showing examples of the present invention. However, as a matter of course, the present invention is not limited to the examples described below.

The compounds used in each of the following examples are as follows.

Compound CB) Example-1 (Preparation of Emulsion Em-1) An emulsion (Em-1) with an average particle size of about 0.5 μm was prepared according to the following formulation.
) grew.

(d) Acetic acid Amount to neutralize to pH 6.5 First,
Solution (b) was added to solution (a) at 40°C, and while stirring, solution (c) was further added over 20 minutes to form a silver iodobromide emulsion.

It was then aged for 30 minutes.

Thereafter, liquid (2) was added to neutralize the mixture to pH 6.5 to obtain a silver iodobromide emulsion with an average grain size of 0.5 μm.

The above is the particle formation step, followed by a desalination step in which excess salt is removed.

The silver halide emulsion formed in the above step was maintained at 40°C, and the compound (A) was mixed at 5 g/1 mole of AgX (AgX represents silver halide; the same throughout this specification) and Mg5O was mixed at 8 g/1 mole of AgX. 1 mole of AgX was added, stirred for 5 minutes, and then left to stand. Thereafter, the supernatant liquid was drained to give a liquid volume of 200 cc per mole of silver halide. Next 40″
1.8ffi/1 mol of AgX pure water of C was added and stirred for 5 minutes.

Next, 20 g/AgX1 mol of MgSO4 was added, stirred and left to stand in the same manner as above, and the supernatant liquid was removed to perform desalting.

This solution was then stirred.

After stirring, post-gelatin was added to redisperse the silver halide and the mixture was dispersed at 55°C. As a result, emulsion E
m-1 was obtained.

(Preparation of Emulsion Em-2) Emulsion Em-2 having an average grain size of 0.5 μm was grown according to the following recipe.

(H) Acetic acid Amount to neutralize to pH 6.5 First,
Solution (f) was added to solution (e) at 40°C, and while stirring, solution (g) was further added over 20 minutes to form a silver iodobromide emulsion.

It was then aged for 30 minutes.

After that, add solution (H) to neutralize to pH 6.5, and the average particle size is 0.
．． A 5 μm silver iodobromide emulsion was obtained.

The emulsion Em-1 was desalted in the same manner as in the case of emulsion Em-1.
-2 was prepared.

(Preparation of emulsions Em-3 and Em-4) Emulsion Em3 having an average grain size of 0.5 μm was grown according to the following recipe.

(l) Gelatin 26 ml / AgX 1 mol "L water 900 ml / Ag As a result of electron microscopy observation, the AgI particles had a particle size of about 0.05 μm.

This Agl fine grain emulsion was kept at 40°C and the above compound (
A) at 5 g/AgX1 mole and M g S Oa at 8
g/1 mol of AgX was added, stirred for 5 minutes, and then allowed to stand still. The supernatant was then drained and 200 g
The liquid volume was set to cc.

Thereafter, 40°C pure water (1,842/AgX1 mole) was added and stirred for 5 minutes. Next, 20g of MgS Oa
1 mol of /AgX was added, stirred and left to stand in the same manner as above, and the supernatant liquid was removed to perform desalting. Next, post-gelatin was added to disperse AgI again, and the mixture was stirred at 55°C for 20 minutes to disperse it. This emulsion (A) was made into an Agl fine grain emulsion.

110L42'' - The above emulsion (A) was prepared as Agl fine particles at 40°C.
The mixture was added to the liquid, and the liquid (e) was further added while stirring. Further, while stirring, solution (W) was added over 20 minutes to form a silver iodobromide emulsion.

It was then aged for 30 minutes. Then add the liquid and adjust the pH
The silver iodobromide emulsion was neutralized to 6.5 to obtain a silver iodobromide emulsion with an average grain size of 0.5 μm.

The emulsion Em-1 was desalted in the same manner as in the case of emulsion Em-1.
-3 was prepared.

Solution (E) was added to solution (L) at 40°C for one day, and while stirring, the emulsion (A) solution was further added in the form of Agl fine particles. Further, while stirring, solution (W) was added over 20 minutes to form a silver iodobromide emulsion.

Other than that, emulsion Em-
4 was prepared.

(Preparation of emulsion Em-5) In the manufacturing process of emulsion Em-3, rhodium trichloride (
Emulsion Em-5 was prepared in the same manner as the above emulsion Em-3, except that (b) it was not mixed in the liquid and (l) it was mixed in the liquid.

(Preparation of emulsion Em-6) In the manufacturing process of emulsion Em-3, rhodium trichloride (
Emulsion Em-6 was prepared in the same manner as the above emulsion Em-3 except that (e) the emulsion was not mixed in the liquid and (e) it was mixed in the liquid.

In the preparation of each of the emulsions Em-1 to Em-6, the above compound (BE) may be used in combination with (or as a substitute for) compound (A) during the desalting step.

(Preparation, processing, and evaluation of samples) After adjusting the pH of these emulsions to 6 and 8, an appropriate amount of potassium iodide was added to each emulsion. Then at 60°C,
Thiourea dioxide 0.5 .mu./AgX 1 mol, sodium thiosulfate 2.1 mg/AgX 1 mol, and chloroauric acid 2.7 .mu./Ag A spreading agent and a hardening agent were added to each matured emulsion, and glycidyl methacrylate (glycidyl methacrylate) 50
A copolymer aqueous dispersion obtained by diluting a copolymer consisting of three monomers (40 wt%, 10 wt% methyl acrylate, and 40 wt% butyl methacrylate) to a concentration of 10 wt% was subbed. A sample was prepared by coating on a polyester film base coated as a liquid so that 4 g of silver per plate was applied and drying. The samples obtained in this way were each exposed to light using a sensitometric light wedge, and developed for 90 seconds with NewXD-90 developer and NewXF fixer using a KX-500 automatic processor manufactured by Konica Corporation. The maximum and minimum concentrations and sensitivity of each sample were determined.

The results are shown in Table-1. Here, the sensitivity was calculated by subtracting the base density and fog density of the obtained sample to find the reciprocal of the amount of light when giving an optical density of 1.0, and expressed as relative sensitivity with the sensitivity of sample Nα1 in Table 1 set as 100. .

In addition, a storage test over time was conducted as follows.

The sample was left in an atmosphere with a temperature of 50°C and a humidity of 70% for 2 days. This sample was exposed and developed as described above. Table 1 shows the maximum concentration after storage over time.

As understood from Table 1, sample No. according to the present invention,
Samples 3 to 6 all have low reversal fog (sufficient sensitivity, high maximum density, high maximum density after storage over time, and good storage stability. In contrast, comparative samples No. 1 and No. 2 were inferior in all respects.

Table-1 Example-2 Unfogged emulsion Em- prepared in Example-1
1 to Em-6 were adjusted to pH 6.8, and then an appropriate amount of potassium iodide was added to each emulsion. Thereafter, 65.8 μm of stannous chloride/1 mole of AgX and 3.0 μm of potassium chloroaurate/1 mole of AgX were added at 60° C., and the mixture was aged until proper fogging was obtained. Samples were prepared in the same manner as in Example 1 using each emulsion that had been ripened. The samples thus obtained were exposed and developed in the same manner as in Example 1, and the maximum and minimum densities and sensitivities of each sample were determined. The results are shown in Table-2. Here, the sensitivity is obtained by subtracting the base density and fog density of the obtained sample to find the reciprocal of the amount of light when the optical density is 1.0.
It was expressed as a relative sensitivity set to 00. Example 1 of storage test over time
I did the same thing.

As is clear from Table 2, the same effects as in Example 1 were obtained in this example as well.

Table 2 [Effects of the Invention] As described above, the present invention provides a direct-positive silver halide photographic light-sensitive material that maintains a satisfactory maximum density, is highly sensitive, has little reversal fog, and has good storage stability over time. Can be done.

Claims (1)

[Claims] 1. In a direct positive silver halide photographic light-sensitive material having at least one direct positive silver halide emulsion layer on at least one surface of the support, at least one of the direct positive silver halide emulsion layers comprises: A direct positive silver halide photographic light-sensitive material characterized in that it contains a silver halide emulsion to which fine silver iodide grains are added and dissolved before the silver halide grain growth is completed.