JPH06337488A - Silver halide photographic sensitive material improved in silver color tone - Google Patents

Abstract

PURPOSE:To provide a silver halide photosensitive material having a low fogging and a high sensitivity and improved in sliver color tone. CONSTITUTION:In a photographic sensitive material in which at least one layer of a sliver halide emulsion is formed on at least one side of a substrate, sliver halide particles contained in the emulsion, is composed of monodispersed twin crystal of iodic sliver bromide or iodic chloride silver having an averaged content rate of less than 1.0% of sliver iodide, having a ratio between particle size and particle thickness of more than 2, and is adjusted so that the averaged content rate of silver iodide on the outer surfaces of the particles is higher than that in a layer inward thereof. Further, this emulsion is chemically aged under the following conditions (1) to (3):(1) the volumetric ratio of the sliver halide particles contained in the sliver halide emulsion layer during the chemical aging is more than 7%; (2) pAg during the chemical aging is more than 8.2 but less than 8.5; and (3) a difference in pAg before and after the addition of a chemical sensitizer is more than 0.3 but less than 0.5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silver halide photographic light-sensitive material, and more particularly to a silver halide photographic light-sensitive material having a low fog and a high sensitivity and an improved silver tone.

[0002]

BACKGROUND OF THE INVENTION In recent years, the consumption of silver halide photographic light-sensitive materials has been increasing. Therefore, the number of silver halide photographic light-sensitive materials developed is increased, and it is required to further accelerate the development processing, that is, to increase the processing amount within the same time. The above tendency can be applied to any field of light-sensitive materials. For example, in the field of medical X-ray light-sensitive materials, the number of X-ray photographs taken is increasing due to a rapid increase in the number of diagnoses and inspection items. Therefore, it is necessary to inform the examinee of the diagnosis result as soon as possible, and therefore rapid processing is desired. Especially for angiography, intraoperative photography, etc., it is essentially necessary to see the photograph in a short time. In order to meet the demands of the medical community, it is necessary to accelerate the automation of diagnosis (imaging, transportation, etc.) and process X-ray film more rapidly. However, when ultra-rapid processing is performed, development processing is often performed at high pH and high temperature (30 to 40 ° C.), which causes deterioration of image quality.

Along with such a trend toward higher image quality, tabular silver halide grains have recently been used in response to the demand for rapid processing. Since the tabular silver halide grains have a large specific surface area, a large amount of sensitizing dye can be adsorbed, and therefore the spectral sensitivity can be increased, and the crossover light as in the light-sensitive material for X rays can be significantly reduced. At the same time, there is a feature that an image with little light scattering and high resolution can be obtained.

Therefore, by using such tabular grains, a silver halide photographic light-sensitive material having high sensitivity and high image quality is expected. However, according to the study by the present inventors, it is not always so simple. , For example, the color tone becomes yellowish. Since the X-ray film is a black-and-white photograph in which a developed silver image is directly viewed by the naked eye as an information source, the color tone of silver forming the image silver is a very important factor. That is,
The color tone influences the tone of the image, and it is strongly desired from the viewpoint of diagnosis that the low-density portion (D = 1.0 equivalent portion) has a black tone without red or yellow-red tint. There is. Many proposals have been made for these obstacles, such as improvement with a color tone agent, but it is difficult to say that all of them cause a load on photographic characteristics.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems of the prior art and to provide a silver halide photographic light-sensitive material having a low fog and a high sensitivity and an improved silver tone.

[0006]

The silver halide photographic light-sensitive material of the present invention which achieves the above object is a silver halide photographic light-sensitive material having at least one silver halide emulsion layer on at least one side of a support. The silver halide grains contained in the silver halide emulsion layer have an average silver iodide content of 1.0 mol% or less and a grain diameter / grain thickness ratio of 2 or more. Dispersed twin crystals are prepared so that the average silver iodide content on the grain surface is higher than that of the inner layer, and the emulsion is chemically ripened under the following conditions. . The volume ratio of silver halide grains contained in the silver halide emulsion layer during chemical ripening is 7% or more. PAg at the time of chemical aging is 8.2 or more and 8.5 or less. The difference in pAg before and after addition of the chemical sensitizer is 0.3 or more and 0.5 or less.

The present invention will be described below. (Silver Halide Grain) Silver halide grains are generally produced and used in the form of a silver halide emulsion containing the grains. The shape of the silver halide grains used in the present invention is a monodisperse twin crystal having a grain diameter / grain thickness ratio of 2: 1 or more. Preferably 50% of the total projected area has a thickness of 0.3μ
Monodispersed twin grains having a ratio of less than m and a grain diameter / grain thickness of 2: 1 or more, more preferably 50% or more of the total projected area has a thickness of less than 0.2 μm and a grain diameter / grain thickness. It is a monodisperse twin crystal grain having a size ratio of 5: 1 to 8: 1.

In the present invention, the particle size is a diameter when a projected image of particles is converted into a circular image having the same area. Grain thickness refers to the distance between two principal planes of tabular grains facing each other. The projected area of a grain can be calculated from the sum of the grain areas. The total projected area and the projected area for determining the grain diameter are both silver halide crystal samples distributed on the sample table to the extent that grains do not overlap,
It can be obtained by taking an image with an electron microscope at a magnification of 10,000 to 50,000 times and measuring the particle diameter on the print or the area at the time of projection (the number of measurement is indiscriminately 100
There shall be 0 or more). The thickness of the particles can be obtained by observing the sample obliquely with an electron microscope.

A particularly preferred highly monodisperse emulsion of the present invention is one in which the breadth of distribution defined by (grain size standard deviation) / (mean grain diameter) × 100 = (breadth of distribution)% is 30% or less. And more preferably 20% or less. Here, the particle size measuring method is based on the above-described measuring method, and the average particle size is a simple average. (Average particle size) = Σd ₁ n ₁ / Σn ₁

In the present invention, twin means a silver halide crystal having one or more twin planes in one grain. The twin morphology is classified by Klein and Moiser in the report “Photographie Correspondents” (Photo
graphische Korrespondenz)
99, 99, 100, 57. Two or more twin planes of a twin may or may not be parallel to each other. The twin plane can be observed directly with an electron microscope, but it can also be observed from the cross section as an ultrathin section sample by dispersing and solidifying silver halide in a resin.

The above-mentioned silver halide twin crystal grains constituting the silver halide emulsion according to the present invention are preferably those mainly having two or more parallel twin crystal planes, more preferably an even number, particularly preferably. Has two twin planes. Here, the term "mainly composed of twins having two or more parallel twin planes" means that the number of twin grains having two or more parallel twin planes is 50 when counted from the large-sized grains. % Or more, preferably 60% or more, particularly preferably 7
This is the case of 0% or more. The monodispersed twin crystal in the present invention is one having a particle size distribution of the twin particles of 30% or less, and more preferably 20% or less.

The silver halide composition of the silver halide emulsion used in the present invention has a silver iodide content of 1.0 mol% or less, preferably 1.0 to 0.05 mol%. Any silver halide of silver bromide may be used. Regarding the halogen distribution in the grain, the halogen composition may be different between the inside and the outside and may have a layered structure (core / shell structure), but the average silver iodide content on the surface of the grain Is prepared so as to be higher than the inner layer by supplying fine silver iodide and / or silver iodobromide.

The silver halide emulsion used in the present invention is formed by a method in which a previously formed silver halide emulsion is used as a seed emulsion and then grains are further grown. The silver halide photographic emulsion which can be used in the present invention may take any method such as an acidic method, a neutral method and an ammonia method, but a double jet method (simultaneous method is used as a method of reacting a soluble silver salt and a soluble halogen salt Mixed method) is used. As one form of the simultaneous mixing method, a method of keeping pAg in a liquid phase where silver halide is formed constant, that is, a so-called controlled double jet method can be used. According to this method, a silver halide emulsion having a regular crystal form and a substantially uniform grain size can be obtained.

(Silver iodide / silver iodobromide fine particles) The fine silver iodide grains and silver iodobromide grains (hereinafter referred to as "fine grains") used in the present invention will be described. Since the grain size of fine grains controls the supply rate of iodine ions, the preferable grain size varies depending on the size of the silver halide grains of the host and the halogen composition, but the average equivalent spherical diameter is 0.
Those having a thickness of 3 μm or less are used. More preferably 0.1
μm or less. In order for the fine particles to be laminated on the host particles by recrystallization, the particle size of the fine particles is preferably smaller than the equivalent spherical diameter of the host particles, and more preferably 1/10 or less of the equivalent spherical diameter. The fine grain halogen composition has a silver iodide content of 95 mol% or more, and is preferably pure silver iodide.

(Hydrophilic Colloid) In the silver halide emulsion according to the present invention, various hydrophilic colloids for wrapping silver halide are used as a binder. For this purpose, gelatin as well as synthetic polymers such as polyvinyl alcohol and polyacrylamide, and photographic binders such as colloidal albumin, polysaccharides and cellulose derivatives may be used.

(Desalting) The silver halide emulsion used in the practice of the present invention has a pAg ion concentration suitable for chemical sensitization by removing soluble salts by an appropriate method after the growth of silver halide grains is completed. be able to. Research Disclosure No. 17643 (Research Disclosure)
e 17643, December 1978), and a preferable washing method is, for example, Japanese Examined Patent Publication No.
-16086 method using an aromatic hydrocarbon aldehyde resin containing sulfonic acid, or JP-A-63-158
Exemplified G-3 and G-8 which are polymer flocculants described in No. 644.
And a desalting method using

(Chemical ripening) In the present invention, the term "chemical ripening" refers to the period from the time when the chemical sensitizer is added to the time when an operation for stopping the chemical ripening is performed thereafter. As a method of ending the chemical ripening, a method of lowering the temperature, a method of lowering the pH, a method of using a chemical ripening stopper, etc. are known, and any method may be used. Further, the addition of the chemical ripening agent may be carried out in several times with a time interval, but the chemical ripening in the present invention starts from the time when the first chemical sensitizer is added. The temperature of chemical aging is 30
The temperature is preferably in the range of -80 ° C, more preferably 40-65.
It is in the range of ° C.

(Photographic Additive) In the photographic light-sensitive material of the silver halide photographic emulsion of the present invention, various photographic additives can be used in the steps before and after physical ripening or chemical ripening of the emulsion. Examples of the compound that can be used in such a step include Research Disclosure (RD) 1 described above.
7643, (RD) 18716 (1979, 11
Month) and (RD) 308119 (December 1989)
Various compounds described in. These 3
The types and locations of the compounds listed in item (RD) are listed below.

Additive RD-17643 RD-18716 RD-308119 Page classification Page classification Page classification Chemical sensitizer 23 III 648 Upper right 996 III Sensitizing dye 23 IV 648-649 996-8 IV Desensitizing dye 23 IV 998B Dye 25-26 VIII 649-650 1003 VIII Development accelerator 29 XXI 648 Upper right fog inhibitor / stabilizer 24 IV 649 Upper right 1006-7 VI Whitening agent 24 V 998 III Hardener 26 X 651 Left 1004-5 X Surfactant Agents 26-27 XI 650 Right 1005-6 XI Plasticizer 27 XXI 650 Right 1006 XXI Sliding Agent 27 XXI Matting Agent 28 XVI 650 Right 1008-9 XVI Binder 26 XXII 1003-4 IX Support 10028 XVII 10028 XVII

Examples of the support used in the silver halide photographic light-sensitive material of the present invention include those described in the above RD. Suitable supports are plastic films and the like, and the surface of the support is coated. An undercoat layer may be provided to improve the adhesion of the layer, or a surface treatment such as corona discharge or ultraviolet irradiation may be applied.

(Processing) The processing of the light-sensitive material of the present invention is carried out, for example, by RD-17643, XX to XXI, 29 to 3.
Pp. 0 or 308119, XX to XXI, 1011
Treatment with a treatment liquid as described on page 1012 may be performed. As developers in black and white photographic processing, dihydroxybenzenes (eg hydroquinone), 3-pyrazolidones (eg 1-phenyl-3-pyrazolidone), aminophenols (eg N-methyl-aminophenol), etc., alone or in combination. Can be used. In the developer, various known additives such as preservatives, alkali agents, pH buffers, antifoggants, film hardeners, development accelerators, surfactants, defoamers, color tones, water softeners. A solubilizing agent, a viscosity imparting agent, etc. may be used as necessary.

A fixing agent such as thiosulfate or thiocyanate is used in the fixing solution and may further contain a water-soluble aluminum salt such as aluminum sulfate or potassium alum as a hardening agent. In addition, it may contain a preservative, a pH adjuster, a water softener, and the like.

[0023]

EXAMPLES Examples of the present invention will be described below. Naturally, the present invention is not limited to the examples described below. Example-1 (Preparation of seed emulsion) A hexagonal tabular seed emulsion was prepared by the following method. <Solution A0> Ocein gelatin 60.2g Distilled water 20.0l

[0024]

[Chemical 1]

KBr 26.8 g 10% H ₂ SO ₄ 144 ml

<Solution B0> 2.5N AgNO ₃ aqueous solution 3500 ml

<Solution C0> KBr 1029 g KI 29.3 g Distilled water up to 3500 ml

<Solution D0> 1.75N KBr aqueous solution The following silver potential control amount

At 35 ° C., Japanese Patent Publication No. 58-58288
No. 58-58289, the mixing stirrer is used to add solution B0 and solution C0 to each of 64.1 m.
1 was added by the double-sided mixing method over a period of 2 minutes to perform nucleation.

After stopping the addition of the solution B0 and the solution C0, it took 60 minutes to raise the temperature of the solution A0 to 60 ° C., and the solution B0 and the solution C0 were mixed again by the simultaneous mixing method.
Each was added at a flow rate of 68.5 ml / min for 50 minutes.
During this period, the silver potential (measured with a silver ion selective electrode using a saturated silver-silver chloride electrode as a reference electrode) was +6 mV using the solution D0.
Controlled to be. After the addition was completed, the pH was adjusted to 6 with 3% KOH, and immediately desalted and washed with water to obtain a seed emulsion EM.
It was set to -0. In the thus-produced seed emulsion EM-0, 90% or more of the total projected area of the silver halide grains consisted of hexagonal tabular grains having a maximum adjacent side ratio of 1.0 to 2.0, and the average thickness of the hexagonal tabular plate was It was found by electron microscope observation that the average diameter (circle diameter conversion) was 0.07 μm and the average diameter was 0.5 μm.

(Preparation of fine silver iodide particles) Fine silver iodide particles were prepared by the following method. <Solution A> Ocein gelatin 100 g KI 8.5 g Make up to 2000 ml with distilled water.

<Solution B> AgNO ₃ 360 g Distilled water up to 605 ml.

<Solution C> 352 g of KI Make up to 605 ml with distilled water. Add Solution A to the reaction vessel, keep at 40 ° C with stirring,
Solution B and solution C were added at a constant rate by the simultaneous mixing method over 30 minutes. The pAg during the addition was kept at 13.5 by a conventional pAg control means. The produced silver iodide has an average grain size of 0.0
It was a mixture of 6 μm β-AgI and γ-AgI. This emulsion is called a silver iodide fine grain emulsion.

(Preparation of Comparative Tabular Emulsions EM-1 to 3)
1.53 mol% Ag using the following three solutions
Tabular silver iodobromide emulsions EM-1 to 3 containing I were prepared. <Solution A1> Ocein gelatin 29.4 g Seed emulsion EM-0 0.588 mol equivalent

[0035]

[Chemical 2] Make up to 2000 ml with distilled water.

<Solution B1> 1404 g of AgNO ₃ 2360 ml with distilled water.

<Solution C1> KBr 968 g KI 20.6 g Make up to 2360 ml with distilled water. At 60 ° C, Japanese Patent Publication Nos. 58-58288 and 58-58
Solution A1 using the mixing stirrer shown in No. 58289.
Then, the total amount of solution B1 and solution C1 was mixed by a simultaneous mixing method so that the flow rate at the end of addition was 3 times the flow rate at the start of addition.
It took 10 minutes to perform additive growth. During this period, the silver potential was controlled to +25 mV by using a 1.75N potassium bromide aqueous solution.

After the addition was completed, the following sensitizing dyes (A) and (B) were added in an amount of 300 mg / Ag / mol and 15 mg / Ag, respectively.
After addition of 1 mol of ossein gelatin 92.I, after the addition of I mol, precipitation desalting was carried out using an aqueous solution of demole (manufactured by Kao Atlas) and an aqueous solution of magnesium sulfate in order to remove excess salts.
An aqueous gelatin solution containing 2 g was added, and the mixture was stirred and redispersed to prepare E.
It was set to M-1. EM-2 to 3 were performed in the same manner as EM-1 until desalting, and the washing water amount for desalting and the water amount of the gelatin aqueous solution were adjusted to the pAg and emulsion volume shown in Table 1.

Sensitizing dye (A): 5,5'-dichloro-9
-Ethyl 3,3-di- (3-sulfopropyl) oxacarbocyanine salt anhydrous

Sensitizing dye (B): 5,5'-di- (butoxycarbonyl) -1,1'-diethyl-3-3'-di-
(4-Sulfobutyl) benzimidazolocarbocyanine-sodium salt anhydrous

Approximately 3000 particles of EM-1 were observed and measured by an electron microscope to analyze the shape. As a result, a flat plate having an average circle-equivalent particle size of 1.05 μm, an average particle thickness of 0.25 μm, and a distribution width of 18%. It was a particle.

(Preparation of Comparative Tabular Emulsion EM-4 to 5) The same procedure as in EM-1 was conducted except that the solution C1 was changed to the solution C2.
EM-4-5 were prepared.

<Solution C2> KBr 975 g KI 10.9 g Distilled water up to 2360 ml.

Approximately 3000 particles of EM-4 were observed and measured by an electron microscope and the shape was analyzed. As a result, a flat plate having an average circle-equivalent particle size of 1.06 μm, an average particle thickness of 0.24 μm, and a distribution width of 18%. It was a particle.

(Preparation of Comparative Tabular Emulsion EM-6 to 7) The same procedure as in EM-1 was conducted except that the solution C1 was changed to the solution C3.
EM-6-7 were prepared.

<Solution C3> KBr 978 g KI 6.86 g Distilled water to make 2360 ml.

Approximately 3000 particles of EM-6 were observed and measured by an electron microscope and the shape was analyzed. As a result, a flat plate having an average circle-equivalent particle size of 1.06 μm, an average particle thickness of 0.24 μm and a distribution width of 18% was obtained. It was a particle.

(Preparation of Comparative Tabular Emulsion EM-8-10)
1.53 mol% Ag using the four solutions shown below
Tabular silver iodobromide emulsions EM-8 to 10 containing I were prepared.

<Solution A4> 29.4 g of ossein gelatin, seed emulsion EM-0 equivalent to 0.588 mol

[0050]

[Chemical 3] Make up to 2000 ml with distilled water.

<Solution B4> 1404 g of AgNO ₃ Make up to 2360 ml with distilled water.

<Solution C4> KBr 902 g KI 17.2 g Distilled water makes 2197 ml.

<Solution D4> KBr 65.8 g KI 2.84 g Make up to 163 ml with distilled water.

At 60 ° C., Japanese Examined Patent Publication No. 58-58288
No. 58-58289, using a mixing stirrer, 2197 ml of the solution B4 and the total amount of the solution C4 are mixed in the solution A4 by the simultaneous mixing method so that the flow rate at the end of the addition is 3 times the flow rate at the start of the addition. It took 102 minutes to perform additional growth. Next, the remaining amount of the solution A4 and the total amount of the solution D4 were added and grown for 10 minutes.

During this period, the silver potential was controlled to +25 mV by using a 1.75N potassium bromide aqueous solution.

After completion of the addition, the sensitizing dyes (A) and (B) were added at 300 mg / Ag 1 mol and 15 mg / Ag, respectively.
After the addition of 1 mol, in order to remove excess salts, precipitation desalting was carried out using a demole (manufactured by Kao Atlas) aqueous solution and an aqueous magnesium sulfate solution, and ossein gelatin 92.
An aqueous gelatin solution containing 2 g was added, and the mixture was stirred and redispersed to prepare E.
It was set to M-8. Further, EM-9 to 10 were carried out in the same manner as EM-8 until desalting, and the washing water amount for desalting and the water amount of the gelatin aqueous solution were adjusted to the pAg and emulsion volume shown in Table 1.

Approximately 3000 particles of EM-8 were observed and measured by an electron microscope and the shape was analyzed. As a result, a flat plate having an average circle-equivalent particle size of 1.05 μm, an average particle thickness of 0.25 μm and a distribution width of 18% was obtained. It was a particle.

(Preparation of Comparative Tabular Emulsions EM-11 to 12) EM-11 to 12 were prepared in the same manner as EM-8 except that the solution C4 was changed to the solution C5.

<Solution C5> KBr 907 g KI 7.0 g With distilled water, make up 2197 ml.

Approximately 3000 particles of EM-11 were observed and measured by an electron microscope and the shape was analyzed. As a result, a flat plate having an average circle-equivalent particle size of 1.06 μm, an average particle thickness of 0.24 μm and a distribution width of 18% was obtained. It was a particle.

(Preparation of Comparative Tabular Emulsion EM-13 to 14) EM-13 to 14 were prepared in the same manner as in EM-8 except that the solution C4 was changed to the solution C6.

<Solution C6> KBr 911 g KI 2.55 g Make up to 2197 ml with distilled water.

Approximately 3000 particles of EM-13 were observed and measured by an electron microscope, and the shape was analyzed. As a result, a flat plate having an average circle-equivalent particle diameter of 1.06 μm, an average particle thickness of 0.24 μm and a distribution width of 18% was obtained. It was a particle.

(Preparation of Comparative Tabular Emulsion EM-15 to 16) Tabular silver iodobromide emulsion EM-15 to 16 containing 1.53 mol% of AgI was prepared using the following five kinds of solutions.
It was created.

<Solution A7> 29.4 g of ossein gelatin, seed emulsion EM-0 0.588 mol equivalent

[0066]

[Chemical 4] Make up to 2000 ml with distilled water.

<Solution B7> 1404 g of AgNO ₃ Make up to 2360 ml with distilled water.

<Solution C7> KBr 902 g KI 17.2 g Make up to 2197 ml with distilled water.

<Solution D7> KBr 67.8 g Make up to 163 ml with distilled water.

<Solution E7> Silver iodide fine grain emulsion 0.017 mol equivalent At 60 ° C., Japanese Patent Publication Nos. 58-58288 and 58-58288
Solution A7 using the mixing stirrer shown in No. 58289.
Then, 2197 ml of the solution B7 and the total amount of the solution C7 were added and grown by the simultaneous mixing method for 102 minutes so that the flow rate at the end of addition was three times the flow rate at the start of addition.
Then, add the rest of solution A7 and the total amount of solution D7 and solution E7 to 1
It took 0 minutes to perform additive growth by the triple jet method. During this period, the silver potential was controlled to +25 mV using a 1.75N potassium bromide aqueous solution.

After the addition was completed, the sensitizing dyes (A) and (B) were added in an amount of 300 mg / Ag 1 mol and 15 mg / Ag, respectively.
After the addition of 1 mol, in order to remove excess salts, precipitation desalting was carried out using a demole (manufactured by Kao Atlas) aqueous solution and an aqueous magnesium sulfate solution, and ossein gelatin 92.
An aqueous gelatin solution containing 2 g was added, and the mixture was stirred and redispersed to prepare E.
It was set to M-15. EM-16 was carried out in the same manner as EM-15 before desalting, and the washing water amount for desalting and the water amount of the gelatin aqueous solution were adjusted to the pAg and emulsion volume shown in Table 1.

Approximately 3000 particles of EM-15 were observed and measured by an electron microscope and the shape was analyzed. As a result, a flat plate having an average circle-equivalent particle size of 1.05 μm, an average particle thickness of 0.25 μm and a distribution width of 18% was obtained. It was a particle.

(Comparative and Inventive Tabular Emulsion EM-17
Preparation of -23) EM- except that the solution C7 is changed to the solution C8
EM-17 to 23 were prepared in the same manner as 15.

<Solution C8> KBr 907 g KI 7.0 g With distilled water, make up 2197 ml.

Approximately 3000 particles of EM-17 were observed and measured by an electron microscope and the shape was analyzed. As a result, a flat plate having an average circle-equivalent particle size of 1.06 μm, an average particle thickness of 0.24 μm and a distribution width of 18% was obtained. It was a particle.

(Comparative and Inventive Planographic Emulsion EM-24 to
Preparation of 29) EM-1 except that the solution C7 is changed to the solution C9
EM-24 to 29 were prepared in the same manner as in Example 5.

<Solution C8> KBr 911 g KI 2.55 g Make up to 2197 ml with distilled water.

Approximately 3000 particles of EM-24 were observed and measured by an electron microscope to analyze the shape. As a result, a flat plate having an average circle-equivalent particle size of 1.06 μm, an average particle thickness of 0.24 μm and a distribution width of 18% was obtained. It was a particle.

(Preparation of Sample) For each emulsion, the sensitizing dyes (A) and (B) were added at 140 mg / Ag1 each.
After adding 1.4 mol / Ag of 1 mol, ammonium thiocyanate was added to 7.0 × 10 ⁻⁴ mol per mol of silver, and chloroauric acid and hypo were added to 4.5 mol per mol of silver.
Chemical ripening was carried out by adding × 10 ^-6 mol and 8.0 × 10 ^-5 mol to obtain a silver iodide grain emulsion having an average grain size of 0.06 μm at 6 × 1.
After adding 0 ^-4 mol / Ag 1 mol, 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene 3 × 10 ^-3
Stabilized on a molar basis.

Table 1 shows the pAg of each emulsion before and after chemical sensitization and the volume ratio of silver halide grains contained in the silver halide emulsion during chemical ripening.

Various additives described below were added to each emulsion.

Additives used in the emulsion liquid (light-sensitive silver halide coating liquid) are as follows. Addition amount is 1 silver halide
It is shown as the amount per mole.

[0083]

[Chemical 5]

T-butyl-catechol 400 mg polyvinylpyrrolidone (molecular weight 10,000) 1.0 g styrene-maleic anhydride copolymer 2.5 g trimethylolpropane 10 g diethylene glycol 5 g nitrophenyl-triphenyl-phosphonium chloride 50 mg 1,3- Ammonium dihydroxybenzene-4-sulfonate 4 g Ammonium 2-mercaptobenzimidazole-5-sulfonate 1.5 mg

[0085]

[Chemical 6] _{n-C 4 H 9 OCH 2} CH (OH) CH 2 N (CH 2 COOH) 2 1g The additives used in the protective layer solution are as follows. The added amount is shown as an amount per 1 g of gelatin. Matting agent composed of polymethylmethacrylate having an area average particle size of 7 μm 7 mg Colloidal silica (average particle size 0.013 μm) 70 mg 2,4-dichloro-6-hydroxy-1,3,5-triazine sodium salt 30 mg (CH ₂ = CHSO ₂ -CH ₂ -) ₂ O 36mg

[0086]

[Chemical 7]

F ₁₉ C ₉ —O— (CH ₂ CH ₂ O) ₁₀ CH ₂ CH ₂ —OH 3 mg or more of the coating solution was applied onto a blue-colored polyethylene terephthalate film base having a thickness of 180 μm and subjected to an undercoating treatment. Samples 1 to 29 were prepared as shown in Table 1 by uniformly coating on both surfaces and drying. The coated gelatin on both sides is 3.
Adjustments were made for all the samples so as to obtain 0 g / m ² .
The amount of silver coated on each sample was 2.0 g / m ² for one side.
I adjusted it to be.

[Evaluation of Sensitometry] The obtained sample was sandwiched with an X-ray photographic intensifying screen KO-250, irradiated with X-ray through a penetrometer type B, and then developed at 35 ° C. using a SRX-501 automatic developing machine. -SR, fixing liquid XF-SR was used to perform DRY to DRY processing for 45 seconds. (All manufactured by Konica Corporation) The sensitivity of each sample developed as described above was evaluated. Sensitivity: Fog of sample 1 +0.1
The reciprocal of the amount of bombardment energy required to give the concentration of 1
The relative value was set to 00. The results are shown in Table 1.

[Silver tone test after development] Sample 30 cm ×
After exposing to 30 cm so that the transmitted light density after development becomes 1.0, it is exposed to 35 ° C. using an SRX-501 automatic developing machine.
DRY t with developer XD-SR and fixer XF-SR
o DRY 45 seconds treatment was performed. (Both manufactured by Konica Corporation) The developed sample thus obtained is 50
After leaving it at a temperature of 80 ° C. and a humidity of 80% RH for 7 days, it was observed with a Schaukasten, and the silver color tone due to transmitted light was visually determined.

The evaluation was performed as follows. 5: Black 4: Slightly reddish black 3: Reddish black 2: Slightly yellow-reddish black 1: Yellow-reddish black The results are shown in Table 1.

[0091]

[Table 1]

[0092]

As shown in Table 1, the samples using the silver halide emulsion of the present invention have low fog, high sensitivity and improved silver tone after development.

Claims (2)

[Claims] 1. A silver halide photographic light-sensitive material having at least one silver halide emulsion layer on at least one side of a support, wherein the silver halide grains contained in the silver halide emulsion layer are It is a silver iodobromide or silver iodochlorobromide monodispersed twin crystal having an average silver iodide content of 1.0 mol% or less and a grain diameter / grain thickness ratio of 2 or more, and an average silver iodide content on the grain surface. The rate is adjusted to be higher than the inner layer,
Furthermore, the silver halide photographic light-sensitive material is characterized in that the emulsion is chemically ripened under the following conditions. The volume ratio of silver halide grains contained in the silver halide emulsion layer during chemical ripening is 7% or more. PAg at the time of chemical aging is 8.2 or more and 8.5 or less. The difference in pAg before and after addition of the chemical sensitizer is 0.3 or more and 0.5 or less. 2. The average silver iodide content on the grain surface is adjusted to be higher than that of the inner layer by supplying fine silver iodide and / or silver iodobromide grains. The silver halide photographic light-sensitive material according to claim 1, which is characterized in that.