JPH0273342A - Direct positive silver halide photographic sensitive material - Google Patents

Abstract

PURPOSE:To obtain a silver halide photographic sensitive material having small minimum density by incorporating silver halide particles which have been fogged by the addition of a reducing agent and an Au compd. after completing a specified stage of a prepn., together with at least one kind of water-soluble inorganic bromides as at least one of silver halide particles constituting an emulsion layer. CONSTITUTION:At least one of silver halide particles constituting an emulsion layer contains a silver halide particle which has been fogged by the addition of a reducing agent and an Au compd. and at least one kind of water-soluble inorganic bromides after coagulating the silver halide particles and a protective colloid with a flocculated polymer in the stage of prepn. of the emulsion layer and removing dissolved substances in a suspending medium. Thus, a silver halide photographic sensitive material having a small minimum density and a stable gamma value without causing decrease of the maximum density necessary for providing a direct positive picture, is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to /X silver halide photographic light-sensitive materials, and more specifically, to direct positive type /X silver halide photographic light-sensitive materials which have been fogged in advance. It is related to property improvement.

[Background of the invention]

Usually, 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, 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, but when used for copying photographs with relatively continuous gradation 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, U.S. Patent No. 3,
As described in No. 615.573, it has been proposed to reduce the contrast by mixing monodisperse direct reversal silver halide photographic emulsions with different fog degrees. The process for producing silver photographic emulsions is relatively complicated, and it is difficult to produce them stably and with good reproducibility. Furthermore, as a simple method in terms of manufacturing process, for example, as described in U.S. Pat. No. 3,364,026, a method of reducing contrast by directly adding a certain type of merocyanine dye of the sensitizing dye type to a positive silver halide emulsion is available. is proposed. However, when such a sensitizing dye is directly added to a positive-working silver halide emulsion, generally, during storage of the direct-positive silver halide photosensitive material,
Because fog nuclei are easily oxidized, the maximum density decreases and gamma changes over time, and after photographic processing of direct positive silver halide light-sensitive materials, dyes remain in the silver halide emulsion, resulting in color contamination. Moreover, it often causes undesirable phenomena.

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, Due to the high content of silver iodide, the geographical properties are poor, leading to poor fixation and penetration, and the eluted iodide contaminates the developer, adversely affecting the processability of other films.

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

JP-A-61-186953 proposes a method of adding water-soluble iodide and then fogging in the presence of thiosulfate and/or thiocyanate, but even this method is not sufficiently effective. 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.

That is, in a photographic light-sensitive material having a direct positive silver halide emulsion layer which has been fogged in advance, at least one of the silver halide grains constituting the emulsion layer is agglomerated with the halogen by an aggregating polymer during production. Silver halide particles and a protective colloid are aggregated, and after removing dissolved substances in a suspending medium, a reducing agent and a gold compound are added to fog the silver halide particles and at least one water-soluble inorganic bromide. It is made using a direct positive type silver halide photographic light-sensitive material which is characterized by the following.

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

Generally, in the manufacturing process of photographic silver halide emulsions,
Silver halide emulsions that have undergone physical ripening are usually subjected to a desalting step to remove excess halides as well as soluble salts such as alkali nitrates and ammonium.

As desalting methods, for example, the Tardel method, dialysis method, and coagulation sedimentation method using a coagulant are known, but among these, the coagulation sedimentation method is superior to other methods and has been widely put into practical use. has been done.

Next, as the aggregating polymer agent according to the present invention, modified gelatin in which 50% or more of the amino groups of gelatin molecules are substituted is advantageously used as a gelatin aggregating agent.

Examples of substitutions for amino groups in gelatin are given in U.S. Patent 2.69.
No. 1.582, No. 2.6-14,928, No. 2.52
It is described in No. 5.753.

Useful substituents include (1) acyl groups such as alkylacyl, arylacyl, acetyl, and substituted or unsubstituted benzoyl (2)
Carbamoyl groups such as alkylcarbamoyl and arylcarbamoyl; (3) sulfonyl groups such as alkylsulfonyl and arylsulfonyl; (4) thiocarbamoyl groups such as alkylthiocarbamoyl and arylthiocarbamoyl; (5) carbon atoms 1 to 18.
straight-chain or branched alkyl groups; (6) substituted or unsubstituted aryl groups such as aromatic heterocycles such as phenyl, naphthyl, pyridyl, and furyl;

Among the preferred agglomerated gelatin agents are acyl groups (-COR')
This is due to a carbamoyl group (-CONRI).

The above R1 is a substituted or unsubstituted aliphatic group (for example, a group having 1 to 1 carbon atoms)
18 alkyl groups, allyl groups), aryl groups, or aralkyl groups (for example, phenethyl groups), and R2 is a hydrogen atom, an aliphatic group, an aryl group, or an aralkyl group. Particularly preferred is the case where R3 is an aryl group and R2 is a hydrogen atom.

Specific examples of agglomerated gelatin agents are illustrated below using amine group substituents.

: Exemplary agglomerated gelatin agent (amine group substituent): G-I
G-2H3-Co-C-CI-13C0CH5CH.

The amount of flocculated gelatin used for desalting is not particularly limited, but is suitably 0.3 to IO times the amount (weight) of gelatin contained as a protective gelatin during desalting, and particularly preferably 1 to It is 5 times the amount (weight).

In addition to the gelatin flocculant described above, examples of the flocculating polymer agent according to the present invention include a polymer flocculant represented by the following general formula (1).

General 2 (1) R. R , , R , in the ZY formula each represent an alkyl group having 1 to 8 carbon atoms, which may be the same or different.

Z and Y each have the formula -〇〇〇M group, -COOR3 group or -M represents a hydrogen atom, an alkali metal atom or an ammonium group, and R represents an alkyl group or an aryl group having 1 to 20 carbon atoms.

Rt and Rs are hydrogen atoms, alkyl groups having 1 to 20 carbon atoms,
In the aryl group, R and R may be bonded to each other to form a heterocycle. n represents an integer of 10 to 104.

In the above general formula (I), the alkyl group of R++Rz has 1 to 8 carbon atoms, and more preferably has 1 to 5 carbon atoms, such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and the like.

These alkyl groups may have a substituent. R,
is an alkyl group having 1 to 20 carbon atoms, preferably 1 to 20 carbon atoms.
-12, such as a methyl group, ethyl group, butyl group, pentyl group, heptyl group, octyl group, dodecyl group, etc., and these alkyl groups may have a substitutable group.

An example of the aryl group is a phenyl group.

R 4,R represents an alkyl group having the same meaning as R;
Examples of the heterocycle formed by bonding 4 and R include a pyridyl group, a morpholino group, and an imidazole group.

Below is the general formula A polymer compound represented by H3 A specific example is shown below.

C11° The above compound is known as a polymer flocculant and is easily available as a commercial product.

The agglomerated polymeric agent represented by the general formula CI) has a molecular weight of 101 to 106, preferably 3 x 10" to
2 x 10', and the amount added is 1750 to 1/4, preferably 1/4 in weight ratio to gelatin contained in the emulsion.
40-1/10.

In an embodiment of the present invention, after adding these coagulating polymer agents, the pH is adjusted to coagulate the AgX emulsion.

The pH for coagulation is 2.0 or more and 5.5 or less, preferably 3.8 or more and 5.0 or less.

The acid used for pH adjustment is not particularly limited, but organic acids such as acetic acid, citric acid, and salicylic acid, and inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid are preferably used.

Heavy metal ions such as magnesium ions, cadmium ions, lead ions, zirconium ions, etc. may be added in combination with the polymer flocculant.

Desalination may be repeated once or several times. When repeating the process several times, the flocculating polymer agent may be added each time desalting is performed, or the flocculating polymer agent may be added only at the beginning.

The emulsion according to the present invention is prepared, for example, by adding a water-soluble silver salt solution and a water-soluble halide solution to a solution containing a protective colloid, and then adding the produced silver halide grains.
It is obtained by flocculating a suspension together with a protective colloid using an aggregating polymer agent and removing dissolved substances in the suspension.

Here, the aqueous solution containing a protective colloid refers to an aqueous solution in which a protective colloid is formed from gelatin or other substances that can constitute a hydrophilic colloid (substances that can become bangs, etc.), and preferably a colloidal protective colloid. It is an aqueous solution containing gelatin.

When carrying out the present invention, if gelatin is used as the protective colloid, the gelatin may be lime-treated or
It may be treated with an acid.

Hydrophilic colloids other than gelatin that can be used as protective colloids include, for example, gelatin derivatives, graft polymers of gelatin and other polymers, albumin,
Proteins such as casein; hydroxyethyl cellulose,
Cellulose derivatives such as carboxymethylcellulose and cellulose sulfate esters; sugar derivatives such as sodium alginate and starch derivatives; polyvinyl alcohol, polyvinyl alcohol partial acetal, poly-N-vinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinyl Various synthetic hydrophilic polymeric substances such as imidazole, polyvinylpyrazole, etc., singly or copolymers.

In the case of gelatin, use the baggy method with a gel strength of 200.
It is preferable to use the above.

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, a backing layer, and an intermediate layer, which are formed as necessary. The other hydrophilic colloids mentioned above can also be used alone or together with gelatin.

The water-soluble silver salt solution and the water-soluble/% halide solution are reacted to obtain the desired silver halide, and are appropriately selected and combined according to the desired silver halide composition.

The agglomerating polymeric agent refers to a polymeric substance capable of aggregating silver oxide grains together with a protective colloid.

Usually, gelatin, which is a protective colloid, is agglomerated and gelled using such an aggregating polymer agent, and a step (so-called desalting step) is performed in which dissolved substances such as soluble salts in the liquid are removed.

The emulsion according to the present invention is prepared by preparing an emulsion containing seed crystals,
It may be obtained by growing particles from seed crystals or without using seed crystals. When seed crystals are used, if the emulsion containing the seed crystals itself is an emulsion according to the present invention using a coagulating polymer agent, all emulsions obtained from this emulsion fall under the category of emulsions according to the present invention.

However, the seed crystal emulsion for obtaining the emulsion according to the present invention does not necessarily have to be the emulsion according to the present invention. Preferably, a seed crystal emulsion according to the present invention is used as a seed crystal, and an emulsion according to the present invention obtained by using the aggregating polymer agent according to the present invention is also used during grain growth from the seed crystal emulsion.

The silver halide composition of the emulsion according to the present invention is arbitrary. For example, silver halides that can be used include silver chloride, silver bromide, silver iodide, silver chlorobromide, silver iodobromide, silver chloroiodide, silver chloride Any 710 silver genide such as silver iodobromide and mixtures thereof are included, but silver iodobromide is particularly preferably used. When silver iodobromide is used, the silver iodide content is not particularly limited, but the average silver iodide content in the entire silver halide grains is 10 mol%.
It is preferably at most 8 mol%, more preferably at most 8 mol%, even more preferably from 2 to 8 mol%.

The emulsion according to the present invention is prepared by adding a water-soluble silver salt solution and a water-soluble halide solution to a solution containing a protective colloid to form silver halide grains. , various techniques can be used.

For example, pA in the liquid phase produced by silver halide, which is one type of simultaneous mixing method, double jet method, and simultaneous mixing method.
A method of keeping g constant, that is, the so-called Chondrold double-jet method, and another form of the double-jet method is the triple-jet method, in which soluble silver salts of different compositions are added independently to and soluble iodine salts) can also be used.

A forward mixing method can also be used, or a method in which particles are formed in an excess of silver ions (so-called back mixing method) can also be used.

According to the Chondrald double jet method, a silver decagenide emulsion having a regular crystal shape and a nearly uniform grain size can be obtained.

In order to obtain regular silver halide grains in this way, it is sufficient to adjust the reaction conditions when growing silver halide grains using a simultaneous mixing method. A method can be used in which a soluble silver salt such as a silver nitrate solution and a halide solution are added in approximately equal amounts to an aqueous solution of a protective colloid, generally with vigorous stirring.

The grain size of silver halide grains is not particularly limited, but
Those having an average particle size of 0.1 to 3 μm are preferable.

More preferably, it is 0.15 to 2 μm.

The emulsion according to the present invention can effectively exhibit the effects of the present invention whether it is a monodisperse emulsion or a polydisperse emulsion.

In addition, it is preferable to use soluble rhodium in the emulsion of the present invention, preferably /A halogenated rhodium salt or hexahalogen rhodium complex salt, etc., and the addition time is before mixing with silver halide, during mixing, or during physical ripening. is desirable, and the amount added is /%0.001-per mol of silver halide.
A range of 100 mmol is preferred.

The silver halide emulsion used in the present invention is given a suitable fog by using a reducing agent and a gold compound for the silver halide emulsion. At least one or more 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 added. Even better fogging can be imparted by containing at least one compound selected from salts.

In the present invention, fogging is imparted by the above method, but water-soluble iodide can be added to the silver halide emulsion before fogging is imparted.

The conditions for treating the silver halide can vary widely, but the pH is generally within the range of 5.5 to 9, preferably 6 to 7. Also, pAg is generally 6.5 to 8.5
The temperature is generally in the range of 40°C to 100°C, preferably 50°C to 70°C.

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

Reducing agents used in the present invention include aldehyde compounds such as formalin, hydrazine, triethylenetetramine,
Organic reducing agents such as organic amine compounds such as thiourea dioxide and imino-amino-methanesulfinic acid, inorganic reducing agents such as stannous chloride, or reducing agents such as amine borane are preferably used.

The concentration of the reducing agent used varies depending on the silver halide grains, application purpose, etc., and also varies depending on the type of reducing agent, but is generally 0.001 mol per mole of silver halide.
~1.00 mmol.

The gold compounds used in the present invention are monovalent and trivalent soluble gold salts, such as chloroauric acid, gold thiocyanate, sodium chloroaurate, potassium aurate, potassium chloroaurate,
Potassium bromoaurate, potassium iodoaurate, potassium gold cyanide, potassium gold thiocyanide, sodium gold thiomaleate, potassium gold thioglucose, etc. are used.

The amount of the gold compound to be used varies depending on the size composition of the silver halide particles, the purpose of application, etc., but is generally within the range of 0.0001 to 0.1 mmol per mol of silver halide, preferably 0.0001 mmol to 0.1 mmol per mol of silver halide. Good results are obtained when used at low concentrations within the range of 0.005 to 0.05 mmol.

Further, as specific examples of thiosulfates and thiothia:l salts that can be used in the present invention, sodium thiosulfate, ammonium thiosulfate, potassium thiocyanate, ammonium thiocyanate, or complex salts thereof are preferably used, and these compounds is generally 0.00 per mole of 7% silver
It is used in a range of 0.03 to 1O60 mmol, preferably 0.005 to 0.5 mmol. The thiosulfate and thiocyanate salts may be used before or during fog formation with the reducing agent and gold, or after fog formation, but the amount required will vary depending on the time of use. , especially when added after fog formation, it is necessary to increase the amount.

Specific examples of the water-soluble inorganic bromide used in the present invention include sodium bromide, lithium bromide, potassium bromide, ammonium bromide, calcium bromide, magnesium bromide, etc. Generally, halogen/silver bromide 1 0.01 per mole
It is used in the range of ~20 mmol, preferably 0.02 ~
10 mmol is used.

The addition time may be before fogging, during fogging, or after fogging, and it is usually added as an aqueous solution.

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 I; alkyl taurine, fluorine-containing compounds selected from those described in JP-A-49-10722, JP-A-49-46733, etc.; Kosho 42
-25203, 43-10245, 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.

Furthermore, for example, Japanese Patent Publication No. 45-2491O, No. 45-298
It is also possible to contain color couplers selected from those described in No. 78 and the like. In addition, a whitening agent, a thickener, a preservative, a matting agent, an antistatic agent, etc. can also be contained as necessary.

The silver halide emulsion according to the present invention includes protective colloids such as gelatin, polyvinyl alcohol, polyvinyl acrylate, polyvinyl pyrrolidone, cellulose ethers, partially hydrolyzed cellulose acetate, and polyethylene oxide grafted with ethylene oxide as described in Japanese Patent Publication No. 49-20530. A wood-loving polymer such as a (N~hydroxylalkyl)β-alanine derivative 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 ethylene 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 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 acetoglyceride are protected and contained to improve film properties, and color couplers and stabilizers are added depending on the purpose. It is also possible to protect and contain agents, etc.

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, 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 improve the adhesion of the emulsion by electron bombardment.

The direct positive silver halide photosensitive material constructed in this manner maintains a predetermined maximum density and contrast, and has photographic properties in which the minimum density does not increase during storage over time.

〔Example〕

EXAMPLES The present invention will be specifically described below with reference to Examples, but the embodiments of the present invention are not limited thereby.

Example 1 A silver iodobromide emulsion having an average grain size of 0.5 μm was prepared according to the following recipe.

Gelatin 25g (a) Potassium iodide 8g water
1,000sff silver nitrate 170g (b) Ammonia water equivalent water
300ma potassium bromide
117g (c) Rhodium trichloride
42n+g water
500mff(di)acetic acid 56%
First, solution (b) was added to solution (a) in an amount necessary to neutralize the pH to 6.0 at 40'O, and while stirring, solution (c) was further added over 3 minutes. After aging at 40'O for 20 minutes, solution (2) was added to neutralize to pH 6.0.

Next, excess soluble salts were removed by desalting methods (a) and (b) shown below.

Desalting method (a) (1) Add 5.5 g/Ag % Le, Mg5O, 8.5
g/1 mol of AgX was added, stirred for 3 minutes, and then left to stand.
Perform decantation.

2. Add 1.8 ff/AgX 1 mol of pure water at 40°C, t, and after dispersing, add 20 g/AgX of MgSO4.
After adding 1 mol and stirring for 3 minutes, let stand and decant.

3. Repeat step 2 above one more time.

4. Add 15 g of post-gelatin/1 mole of AgX and water, 4.
After finishing to 50cc/AgX 1 mol, 2
Stir for 0 minutes to disperse.

In this way, Emulsion-1 was obtained.

Desalting method (b): 1. Add 50% of the above-exemplified flocculated gelatin agent G-8 as a flocculating polymer agent to the mixed reaction solution at 40°C.
g/AgX 1 mol was added, then 56 wt% acetic acid H
AC llOμI! Add 1 mole of 1/Agx and adjust the pH to 5.
01: Drop, let stand, and decant.

2.40°C (1) After adding 1.8 (2/ AgX 1 mol) of pure water, KOFI (i, 3 g/AgX 1 mol processing, puwo 6.0 ni L, dispersed. Well dispersed. After this, 70 cc of 56 vt% HAC/1 mol of AgX is added to adjust the pH to 4.5, and the mixture is left to stand and decanted.

3. Repeat step 2 above once again.

4. After that, post-gelatin 15g/AgX l%/L-
Add KOH1g/AgX and water, 450cc/Ag
Finish to 1 mole of X.

In this way, emulsion-2 was obtained. The above desalination method (b)
This corresponds to a means for removing dissolved substances to obtain an emulsion according to the present invention.

Furthermore, in the desalting method (b), exemplary flocculated gelatin agent G-
Emulsions 3 to 7 were obtained in exactly the same manner as Emulsion-2 except that Emulsion 8 was changed to G-1, G-3, G-5, G-7, and G-8.

In addition, G-850g/AgX l mole was added to P-1, P-3,
P-6.

Emulsions 8 to 11 were obtained in exactly the same manner as Emulsion-2 except that the ratio was changed to 1 g of P-7/1 mol of AgX.

Next, each emulsion was adjusted to pH 6.8, and 0.7 g of potassium iodide per mole of AgX was added to each emulsion, followed by 0.3 mg of thiourea dioxide at 60°C.

Sodium thiosulfate 1.2+og and chloroauric acid 1.5m
g was added and aged until proper fog was obtained.

A water-soluble inorganic bromide was added to the ripened emulsion as shown in Table 1, and a spreading agent and a hardening agent were added, followed by a copolymer consisting of three types of heptadons: 50 vt% glycidyl methacrylate, 10 vt% methyl acrylate, and 4 Qwt% butyl methacrylate. A copolymer aqueous dispersion obtained by diluting the polymer to a concentration of 10 wt % was coated as a subbing liquid on a polyester film base, and 4 g of silver per square meter was applied.
A sample was prepared by coating and drying it so that it would look like this. The samples obtained in this way were each exposed to light using a sensitometric light wedge and
0 automatic developer, New XD-90 developer, Ne
w Development processing was performed for 90 seconds using an XF fixer, and the maximum and minimum densities and gamma and gamma of each sample were determined. The results are shown in Table 1.

The deterioration test sample was exposed to an atmosphere at a temperature of 50°C and a humidity of 70% for 2 days.As is clear from the results of 1, the emulsion desalted with a formalin condensate of naphthalene sulfonic acid did not improve the photographic properties. On the other hand, it can be seen that by using a water-soluble bromide in an emulsion desalted with the coagulating polymer agent according to the present invention, it is possible to maintain the maximum density and directly convert to a positive image with a small minimum density. Furthermore, even in a severe forced deterioration test, the characteristics of the samples of the present invention did not deteriorate.

Example 2 After adjusting the pH of emulsions 1 to 7 prepared in Example 1 to 6.8, 0.7 g of potassium iodide was added per 1 mole of AgX, and 1.5 mg of triethylenetetramine and 1.5 mg of chloroauric acid were added at 55°C. 5mg and ammonium thiocyanate 2.0mg
The mixture was aged until a suitable fog was obtained. After each ripening was completed, a spreading agent and a hardening agent were added, and the coating was dried in the same manner as in Example 1 to prepare a sample.

Table 2 shows the results of the same treatment as in Example 1.

Both No and Gamma, It was satisfying.

As is clear from Table 2, samples Nos. 23 to 28, which were desalted by the method of the present invention and fogged with a reducing agent and gold salt, and then used water-soluble bromide, had the maximum concentration and the minimum concentration [invention Effects of the Invention] According to the present invention, a silver halide photographic light-sensitive material which is a direct positive image without decreasing the maximum density, has a low minimum density, and exhibits stable gamma can be obtained.

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

Claims (1)

[Claims] In a photographic light-sensitive material having a direct positive-working silver halide emulsion layer which is fogged in advance, at least one of the silver halide grains constituting the emulsion layer is agglomerated with the halogen by an aggregating polymer agent during production. Silver halide particles and a protective colloid are aggregated, and after removing dissolved substances in a suspending medium, a reducing agent and a gold compound are added to fog the silver halide particles and at least one water-soluble inorganic bromide. A direct positive silver halide photographic material characterized by: