JP2000275774A - Silver halide photographic sensitive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a silver halide photographic sensitive material excellent in residual color and stably exhibiting superior gradation reproducibility by spectrally sensitizing emulsion grains with a specified sensitizing dye and specifying characteristics in exposure with laser light. SOLUTION: The silver halide photographic sensitive material contains emulsion grains spectrally sensitized with at least one of sensitizing dyes of formulae I and II. When the sensitive material is exposed with laser light having 600-700 nm wavelength, the gradient of a characteristics curve obtained from optical density and the logarithm of light exposure does not exceed 3 over the entire region. In the formulae, Z and Z2 are each a group of formula III or the like, Y1-Y4 are each O, S or the like, L1 and L2 are each an optionally substituted methine, (n) is 1 or 2, R1-R4 are each an optionally substituted alkyl, R5 and R6 are each H, hydroxy, a halogen, alkyl or the like and M1 and M2 are each a counter ion for neutralizing an electric charge in each molecule.

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 having excellent storage stability, and more particularly to a silver halide photographic light-sensitive material used for a laser imager in medical imaging.

[0002]

2. Description of the Related Art In recent years, in the medical field, in order to obtain a hard copy of an output image of a diagnostic apparatus such as X-ray CT and MRI, a method of obtaining a transmission photographic image by laser scanning exposure corresponding to an output signal from each modality. The number of such laser imagers installed has been increasing steadily. Also, with the development of computer technology, the recording speed has been dramatically improved, and there has been a strong demand for shortening the processing time of photosensitive materials. In order to meet this demand, if the development, fixing, washing, and drying processes of the automatic development process are shortened and high-speed processing is to be achieved, the processing solution flows out, or the processing solution alkali, acid, sulfite ions, etc. In some cases, decolorization of the dye in the photographic material, which has been decolorized, does not proceed sufficiently, and a residual color that may cause a practical problem may occur.

[0003] Images used for image diagnosis are higher in sharpness, graininess, and graininess than ordinary ornamental images.
A linear and stable contrast is required, and as a method for achieving the object, a method using two or more kinds of silver halide emulsion grains having different grain sizes as described in JP-B-61-35537 is used. Can be obtained. Furthermore, according to this technology, a high blackening density can be obtained with a small amount of silver due to a high covering power of fine particles, and the sharpness of patient data etc. burned together with an image is also improved. There is also the advantage of doing so.

On the other hand, recently, as a light source of a laser imager used for such a purpose, 600 to 700 n is used.
Semiconductor lasers having a wavelength of m are small and inexpensive and have become widespread, and are expected to become the mainstream in the market in the future. For this purpose, the silver halide photographic material used in this imager must be Must be sensitized. However, since the sensitizing dye used for spectral sensitization of such a sensitizing material for laser imagers has a photosensitive wavelength in the visible region, it is necessary to add an amount necessary to impart sufficient sensitivity to laser exposure. In this case, there is a problem that the level of the residual color is often high.

As a method for obtaining high spectral sensitivity, spectral sensitization having extremely sharp absorption provided by a special aggregate called J-aggregate is known, but as described above, emulsion grains having different particle sizes are used. If emulsion sensitized emulsion particles of different particle sizes were present in the same coating liquid, the sensitivity of each emulsion may fluctuate due to rearrangement when staying in the coating liquid state, or a different coating liquid However, even when the multi-layer coating is performed simultaneously, the fluctuation of the sensitivity for each particle during storage after the coating is different, which causes a problem of unstable contrast. In the case of a sensitizing dye having such a high degree of adsorption, the development progress of each particle is affected by spectral sensitization, and the contrast often fluctuates during rapid processing or processing with a tired solution.

[0006]

An object of the present invention to solve the above problems is to provide a silver halide photographic light-sensitive material which is excellent in residual color and stably exhibits excellent gradation reproducibility. Is to provide.

[0007]

The above objects of the present invention have been attained by the following present invention.

At least one surface of the support has a light-sensitive silver halide emulsion layer containing at least two types of silver halide emulsion grains having different grain sizes, and each of the emulsion grains has the following general formula ( When spectrally sensitized by at least one sensitizing dye selected from the sensitizing dyes represented by 1) and (2) and exposed to laser light having a wavelength of 600 to 700 nm, the optical density is adjusted to the exposure amount. A silver halide photographic light-sensitive material characterized in that the slope thereof does not exceed 3 over the entire characteristic curve obtained with respect to the logarithm.

[0009]

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In the formula, Z ₁ is a general formula (A), (B),
(C) is shown. Y ₁ represents an oxygen atom, a sulfur atom, a selenium atom, or NR ₁₁ . L ₁ and L ₂ represent a methine group which may be substituted. n is 1 or 2. R ₁₁ and R ₁ represent an alkyl group which may be substituted. Further, when Z ₁ is represented by the general formula (A), at least one of R ₁ and R ₄ is
When Z ₁ is represented by the general formula (B), at least one of R ₁ and R ₇ is: When Z ₁ is represented by the general formula (C),
At least one of R ₁ and R ₉ is substituted with a water-soluble group. M ₁ represents a counter ion for neutralizing the charge of the molecule.

[0011]

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In the formula, Z ₂ is a general formula (A), (B),
(C) is shown. Y ₂ and Y ₃ represent an oxygen atom, a sulfur atom, a selenium atom, and NR ₁₂ . L ₁ and L ₂ represent a methine group which may be substituted. n is 1 or 2. R ₁₂ , R ₂ ,
R ₃ represents an optionally substituted alkyl group. Furthermore, Z ₂
If If is represented by the general formula (A), at least one of R _2, R _3, R ₄ is, that Z ₂ is represented by the general formula (B),
R _2, R _3, at least one of R ₇ is, Z ₂ is Formula (C)
When represented by at least one of R ₂ , R ₃ , R ₉ is
It is substituted with a water-soluble group. M ₂ represents a counter ion for neutralizing the charge of the molecule.

[0013]

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In the formula, Y ₄ represents an oxygen atom, a sulfur atom, a selenium atom, or NR ₁₃ . R ₁₃ and R ₄ represent an alkyl group which may be substituted. R ₅ and R ₆ each independently represent a hydrogen atom,
Hydroxy group, halogen atom, alkyl group, alkenyl group, alkoxy group, alkylthio group, arylthio group,
It represents an aryl group, an acyl group, an acyloxy group, an alkoxycarbonyl group, an alkylsulfonyl group, a carbamoyl group, a sulfamoyl group, a carboxyl group, or a cyano group. The above substituents may be further substituted. further,
R ₅ and R ₆ may be bonded to each other to form an aliphatic ring or an aromatic ring, and in this case, one or more of the substituents described for R ₅ and R ₆ which may be the same or different May be substituted.

[0015]

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In the formula, R ₇ represents an optionally substituted alkyl group. R ₈ each independently represents an alkyl group, an alkenyl group, an alkoxy group, a sulfo group, or a halogen atom. m
When R is 2 or more, a plurality of R ₈ may be the same or different, and may be linked to each other to form a ring.

[0017]

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In the formula, R ₉ represents an alkyl group which may be substituted.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
In the sensitizing dyes represented by the following general formulas (1) and (2), L ₁ , L ₂ , L ₃ and L ₄ may be substituted. Specific examples of the substituent include lower alkyl groups such as methyl group, ethyl group and isopropyl group, alkoxy groups such as methoxy group and ethoxy group, aryl groups such as amino group, phenyl group and naphthyl group, methylthio group and ethylthio group. Examples include heterocyclic groups such as an alkylthio group, a thienyl group, a furyl group, and a tetrahydropyranyl group.

Examples of the water-soluble group which can be introduced into R ₁ , R ₂ , R ₃ , R ₄ , R ₇ and R ₉ include a carboxymethyl group, a sulfoethyl group, a sulfopropyl group and a sulfobutyl group. Can be The water-soluble group may be esterified without taking the form of a free acid.

M ₁ and M ₂ represent inorganic or organic cations, and specific examples include hydrogen ions, sodium ions, potassium ions, and quaternary salts (triethylammonium ion, triethanolammonium ion DBU ion) and the like. . Specific examples of the sensitizing dye represented by the general formulas (1) and (2) are shown below, but the present invention is not limited to these.

[0022]

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[0023]

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[0024]

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[0025]

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The sensitizing dyes represented by the above general formulas (1) and (2) are described, for example, in "Cyanine Soybeans and Related Compounds" by FM Hammer (John
Willy and Sons, published in 1964) or JP-A-3-171135, 6-31.
3943, 7-287337, Japanese Patent Application No. 10-3082
9 can be synthesized.

The silver halide light-sensitive material of the present invention must have a gradient (gamma value) not exceeding 3 over the entire range of the characteristic curve in order to provide the density gradation required for diagnosis. In order to satisfy this condition in standard processing, the contrast of the silver halide light-sensitive material of the present invention can be adjusted by the type of emulsion grains used, dope of emulsion grains, chemical sensitization, organic additives and the like. .

The silver halide emulsion used in the silver halide photographic light-sensitive material of the present invention comprises two or more kinds of silver halide grains having different grain sizes, and each silver halide grain has an arbitrary halide composition. sell. When it contains iodide, its content is at most 3 mol%, more preferably at most 1 mol%. The iodide may be present uniformly in the particles, or may be localized inside or on the surface of the particles. The shape of the silver halide grains may be irregular or plate-like in addition to regular crystals such as cubic and octahedral, and cubic ones are particularly preferred.

For the grain formation of the silver halide emulsion used in the present invention, methods known in the art, such as forward mixing, reverse mixing, and simultaneous mixing, are used. Among them, the so-called controlled double jet method, which is one of the simultaneous mixing methods and maintains pAg in a liquid phase in which particles are formed, is preferably used by mixing two or more kinds of particles having different particle diameters to obtain a desired sensitivity, It is preferable in obtaining contrast. Each of the particles has a coefficient of variation represented by {(standard deviation of particle diameter) / (average particle diameter)} × 100 of 15% or less, more preferably 10% or less.

The grain size of the silver halide emulsion grains used in the present invention can be freely selected as long as the object of the present invention is achieved. Any number of two or more kinds of silver halide grains may be mixed. However, as long as the desired gradation can be obtained, it is preferable that the number of silver halide grains is as small as possible without complicating the process. There are many. In this case, the particles having a small particle diameter covering the low sensitivity region preferably have a sphere equivalent diameter of 0.35 μm or less in consideration of covering power. Further, the difference between the particle size and the large particle is preferably 0.3 μm or more.

The silver halide emulsion grains used in the present invention may be doped with iridium ions in order to give high sensitivity in high-intensity short-time exposure with laser light. In general, the doping amount is preferably 10 ^-8 to 10 ^-5 mol per mol of silver halide. For various purposes,
Cadmium salts, lead salts, zinc salts, thallium salts, rhodium salts and complexes thereof, iron salts and complexes thereof may be contained.

The silver halide emulsion used in the present invention is:
It is preferable to sensitize with various chemical sensitizers, and methods commonly used in the art such as a sulfur sensitization method, a selenium sensitization method, and a noble metal sensitization method can be used alone or in combination. Particularly, in the present invention, the gold sulfur sensitization method is preferable.

The silver halide photographic light-sensitive material of the present invention comprises
Known photographic additives can be used for various purposes. These are Research Disclosure Item 17643
(December 1978) and 18716 (November 1979) 308119 (198
December 1999) or in the cited references.

As the support which can be used as the silver halide light-sensitive material of the present invention, any support known in the art can be used, and in particular, polyester films such as cellulose acetate and polyethylene terephthalate are exemplified. be able to. These supports are
If necessary, an undercoating process or an antistatic treatment may be performed.

The developing agents used for processing the silver halide photographic light-sensitive material of the present invention include dihydroxybenzenes (for example, hydroquinone), aminophenol developing agents (for example, N-methyl-p-aminophenol), and 3-
Pyrazolidone developing agents (for example, 1-phenyl-3-pyrazolidone, 1-phenyl-4,4-dimethyl-3-pyrazolidone, 1-phenyl-4-methyl-3-pyrazolidone, 1-phenyl-4,4-dihydroxymethyl -3
-Pyrazolidone) alone or in combination. Particularly, a combination of hydroquinone and 3-pyrazolidones or a combination of hydroquinone and aminophenols is useful for high-temperature rapid treatment.

The developer used for processing the silver halide photographic light-sensitive material of the present invention includes a preservative, an alkali agent, a pH buffer, an organic or inorganic antifoggant, a water softener, a development accelerator, and a color tone. Adjusters, surfactants, defoamers, hardeners, dissolution aids, thickeners and the like may be used as necessary.

The developing temperature is usually selected between 18 ° C. and 50 ° C., and more preferably 25 ° C. to 40 ° C. The processing method of the present invention is particularly suitable for rapid processing using an automatic developing machine. As the automatic developing machine, any of a roller-conveying machine, a belt-conveying machine and the like can be used.
The processing time may be short, and the developing time is preferably 5 to 60 seconds. Since the slope of the characteristic curve of the processed light-sensitive material can vary depending on the development conditions, particularly in the present invention, conditions must be selected such that the slope does not exceed 3 over the entire area.

In the fixing solution, sodium thiosulfate, ammonium thiosulfate or the like is used as a fixing agent, water-soluble aluminum (eg, aluminum sulfate, potassium alum, etc.) as a hardening agent, and dibasic acid as an aluminum precipitation inhibitor. (E.g., tartaric acid, potassium tartrate, sodium tartrate, sodium citrate, lithium citrate, potassium citrate, etc.), and further may contain sulfites, bisulfites as preservatives, acetic acid, boric acid, etc. as pH buffers. .

[0039]

EXAMPLES The present invention will be described below in detail with reference to examples, but is of course not limited thereto. Example 1 <Preparation of silver iodobromide emulsion> A deionized lime-treated ossein gelatin aqueous solution (8% by weight) was maintained at 60 ° C.
The following compound HS was added in an amount of 15
0 mg, while maintaining the pAg at 7.5, an aqueous solution of silver nitrate and an aqueous solution of potassium bromide and potassium iodide (including potassium hexachloroiridate (III) in an amount of 2.5 × 10 ⁻⁷ mol per mol of silver) ) Was added over 80 minutes by the double jet method to obtain monodispersed cubic silver iodobromide particles (0.5 mol% of iodide) having an average particle size of 0.28 μm and a variation coefficient of 13%. This emulsion was coagulated by flocculation using a styrenesulfonic acid-maleic anhydride copolymer and sodium sulfate as a coagulation aid, washed with water, and re-dissolved by adding gelatin to obtain emulsion A.

The emulsion A before the coagulation and desalting was used as a seed crystal, and an aqueous silver nitrate solution and an aqueous halide solution having the same composition as those of the emulsion A were added by a double jet method over 50 minutes to give an average grain size of 0. Monodispersed cubic silver iodobromide grains (0.5 mol% iodide) having a variation coefficient of 0.65 μm and 9% were obtained. This emulsion was coagulated by flocculation using a styrenesulfonic acid-maleic anhydride copolymer and sodium sulfate as a coagulation aid, washed with water, and re-dissolved with gelatin to obtain emulsion B.

Emulsion A differs from Emulsion A only in that the flow rate of the aqueous silver nitrate / halide solution at the start of mixing is reduced and the pAg is set to 8.5 for the first 5 minutes. An aqueous solution of the iodide was added by a double jet method over 90 minutes to obtain monodispersed cubic silver iodobromide particles (0.5 mol% of iodide) having an average particle diameter of 0.35 μm and a variation coefficient of 15%. This emulsion was coagulated by flocculation using a styrenesulfonic acid-maleic anhydride copolymer and sodium sulfate as a coagulation aid, washed with water, and re-dissolved by adding gelatin to obtain emulsion C.

Each of the emulsions A to C obtained as described above
At 5 ° C., sodium thiosulfate, chloroauric acid and ammonium thiocyanate were added to perform optimal chemical sensitization according to a conventional method, and then 4-hydroxy-6-methyl-1,3,3, a, 7 was added.
-Tetrazaindene was added. The chemically sensitized emulsion A and the emulsion B were mixed at a ratio of 20:80 in terms of silver and the emulsion C were chemically sensitized, and the sensitizing dyes shown in Table 1 and the following additives were added. A silver halide emulsion coating solution was prepared. 5-nitroindazole 8 mg 5-methylbenzotriazole 10 mg Styrene-maleic anhydride copolymer (Mw = 3000) 3 g Surfactant S-1 1.5 g Acrylate latex 6 g 1,3-vinylsulfonyl-2 per mole of silver halide -Propanol 0.8g

[0043]

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[0044] (Preparation of emulsion surface side protective layer coating solution) 1 m ² per acid processed ossein gelatin 1.2g Colloidal silica 0.5g polymethylmethacrylate particles (4 [mu] m) 10 mg acrylate latex 0.2g of sodium polystyrenesulfonate 150mg surfactant S- 1 40mg Surfactant S-2 0.7mg 1,3-vinylsulfonyl-2-propanol 40mg

[0045]

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The above silver halide emulsion layer and protective layer were simultaneously coated on a subbed 7 mil polyethylene terephthalate base having a backing layer of the following composition. Note gelatin silver halide emulsion layer, 1 m ² per 2.
8 g. Further, the emulsion coating solution was kept at 36 ° C. for 12 hours while keeping the temperature, and the coated product was used as a coating solution retention sample. All samples were annealed at 40 degrees for 7 days and then evaluated as follows.

(Preparation of Backing Layer Coating Solution) Lime-treated gelatin 3.0 g per 1 m ² Polymethyl methacrylate particles (6 μm) 20 mg Acrylate latex 1 g Antihalation dye AH-1 100 mg Sodium polystyrene sulfonate 250 mg Surfactant S-1 60 mg Interface Activator S-2 0.7mg 1,3-vinylsulfonyl-2-propanol 120mg

[0048]

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Sensitometry is based on H at a wavelength of 633 nm.
After printing a wedge image with an e-Ne laser beam, a developer having the following composition is used to make
The processing was carried out at 36 ° C. for 20 seconds using a processor 260 roller transport type automatic developing machine. The contrast has two types of gamma values (gamma 1: Dmin +
0.1 to Dmin + 1.3, gamma 2: Dmin + 1.
3 to Dmin + 2.5), and the sensitivity value is Dmin + 1.3.
Was evaluated by the reciprocal of the exposure amount giving The residual color is visually evaluated on a scale of 5; 5 is the best, 1 is the worst, and 3 is the practically acceptable limit. The results are shown in Table 1.

<Formulation of developer> Potassium sulfite 60 g Potassium carbonate 45 g Potassium hydroxide Amount required to make pH 10.5 Hydroquinone 15 g 4-methyl-4-hydroxymethyl-1-phenyl 1.0 g -3-pyrazolidone diethylenetriaminepentaacetic acid 1.2 g Potassium bromide 5.0 g 5-Methylbenzotriazole 0.3 g Compound (AS) 0.4 g Add water to make 1 liter.

[0051]

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[0052]

[Table 1]

From Table 1, it can be seen that the silver halide photographic light-sensitive material of the present invention has stable sensitivity and contrast when the emulsion stays, and is excellent in the level of residual color.

Example 2 <Preparation of silver chloroiodide bromide emulsion> A deionized lime-treated ossein gelatin aqueous solution (8% by weight) was kept at 55 ° C, and the following compound HS was added at a rate of 10% per kg of the gelatin aqueous solution.
0 mg was added, and while maintaining the pAg at 8.5, an aqueous solution of silver nitrate and an aqueous solution of sodium chloride, potassium bromide, and potassium iodide (a potassium hexachloroiridate (III) in an amount of 1.7 × 10 ⁻⁷ mol per mol of silver were added) ) Was added over 90 minutes by the double jet method, and the average particle size was 0.1.
Monodisperse cubic salt silver iodobromide grains having a variation coefficient of 25 μm and 14% (chloride 69.5%, bromide 30%, iodide 0.5
Mol%). This emulsion was washed with water in the same manner as in Example 1,
Emulsion D was obtained by adding gelatin and re-dissolving.

Emulsion D before the coagulation and desalting was used as a seed crystal, and an aqueous silver nitrate solution and an aqueous halide solution having the same composition as in Emulsion C were added by a double jet method over 120 minutes while keeping the pAg at 8.5. And the average particle size is 0.6
Monodisperse cubic silver iodobromide grains having a variation coefficient of 8 μm and 11% (having the same halide composition as Emulsion D) were obtained. This emulsion was washed with water in the same manner, and gelatin was added and redissolved.
And

Emulsion D was different from emulsion D only in that the flow rate of the aqueous silver nitrate / halide solution at the start of mixing was reduced and the temperature was set at 62 ° C. , Added by a double jet method over 120 minutes to obtain an average particle size of 0.37 μm.
Monodisperse cubic silver iodobromide grains having a coefficient of variation of 14% (having the same halide composition as emulsion D) were obtained. This emulsion was similarly washed with water, and gelatin was added and redissolved to obtain Emulsion F.

Each of the emulsions D to F obtained as described above
At 0 ° C., sodium thiosulfate and chloroauric acid were added, and after optimal chemical sensitization according to a conventional method, 1-phenyl-5-mercaptotetrazole was added. The sensitizing dyes shown in Table 2 and the following additives were added to a mixture of the chemically sensitized emulsions D and E at a ratio of 30:70 in terms of silver amount and a chemically sensitized emulsion F. A silver halide emulsion coating solution was prepared. Per mole of silver halide Benzotriazole 30 mg Styrene-maleic anhydride copolymer (Mw = 3000) 4.5 g Surfactant S-1 1.5 g Acrylate latex 6 g 1,3-vinylsulfonyl-2-propanol 0.8 g

The above silver halide emulsion layer and the same protective layer as in Example 1 were simultaneously coated on the same polyethylene terephthalate base as in Example 1. The amount of gelatin in the silver halide emulsion layer was 2.8 g / m ² . All samples were annealed at 40 degrees for 7 days.

The sample prepared as described above was used for He-Ne
Wedge image exposure and test pattern exposure (based on SMPTE, RP-133) by laser imager of light source
Using the same developing solution as in Example 1, and a model fatigue solution obtained by treating No. 20 sample by 3 m ² without replenishment per liter of the developing solution, processing was performed at a developing time of 36 ° C. for 20 seconds. The gamma value and the sensitivity value were defined as in Example 1. In the test pattern exposure, the reference laser intensity was adjusted so that the reproduction of 50% of the gray scale became an optical density of 1.3. The linearity of the gray scale (0 to 100%) in the test pattern and the contrast were visually evaluated in five steps to determine whether the reproduction of the difference of 5% between the highlight portion and the shadow portion could be confirmed simultaneously. 5 is the best, 1 is the worst, and 3 is the practically acceptable limit level. The results are shown in Table 2.

[0060]

[Table 2]

From Table 2, it can be seen that the silver halide photographic light-sensitive material of the present invention shows linearity,
It can be seen that the contrast is stable.

[0062]

According to the present invention, two or more kinds of silver halide emulsion grains different in grain size, containing a sensitizing dye having a specific structure, and having a slope of 3 over the entire characteristic curve when subjected to laser exposure. Silver halide photographic materials that cannot exceed
It has low residual color and stably gives good tone reproducibility.

Claims (1)

[Claims] 1. A photosensitive silver halide emulsion layer comprising at least one silver halide emulsion grain having at least one particle size different from each other on at least one surface of a support. When exposed with a laser beam having a wavelength of 600 to 700 nm, which is spectrally sensitized by at least one sensitizing dye selected from the sensitizing dyes represented by the formulas (1) and (2), the optical density is exposed. A silver halide photographic light-sensitive material characterized in that its slope does not exceed 3 over the entire characteristic curve obtained with respect to the logarithm of the amount. Embedded image In the formula, Z ₁ represents the general formulas (A), (B), and (C). Y ₁
It represents an oxygen atom, a sulfur atom, a selenium atom, a NR _11.
L ₁ and L ₂ represent a methine group which may be substituted. n is 1 or 2. R ₁₁ and R ₁ represent an alkyl group which may be substituted. Furthermore, if Z ₁ is represented by the general formula (A), at least one of R _1, R ₄ is, Z ₁ is the general formula (B)
If in represented by at least one of R _1, R ₇ is, if Z ₁ is represented by the general formula (C), and at least one of R _1, R ₉ is substituted with soluble water-soluble group. M ₁ represents a counter ion for neutralizing the charge of the molecule. Embedded image In the formula, Z ₂ represents the general formulas (A), (B), and (C).
Y ₂ and Y ₃ are oxygen atom, sulfur atom, selenium atom, NR
Represents ₁₂ . L ₁ and L ₂ represent a methine group which may be substituted. n is 1 or 2. R ₁₂ , R ₂ and R ₃ represent an alkyl group which may be substituted. Furthermore, if Z ₂ may be represented by the general formula (A), at least one of R _2, R _3, R ₄ is, that Z ₂ is represented by the general formula _{(B), R 2, R} 3,
When at least one of R ₇ is Z ₂ represented by the general formula (C), at least one of R ₂ , R ₃ , and R ₉ is substituted with a water-soluble group. M ₂ represents a counter ion for neutralizing the charge of the molecule. Embedded image Wherein Y ₄ is an oxygen atom, a sulfur atom, a selenium atom, NR
Represents ₁₃ . R ₁₃ and R ₄ represent an alkyl group which may be substituted. R ₅ and R ₆ each independently represent a hydrogen atom, a hydroxy group, a halogen atom, an alkyl group, an alkenyl group, an alkoxy group, an alkylthio group, an arylthio group, an aryl group, an acyl group, an acyloxy group, an alkoxycarbonyl group, and an alkylsulfonyl group. , A carbamoyl group, a sulfamoyl group, a carboxyl group, and a cyano group. The above substituents may be further substituted. Further, R ₅ and R ₆ may be linked to each other to form an aliphatic ring or an aromatic ring. In this case, one of the substituents described for R ₅ and R ₆ may be the same or different. It may be substituted with one or more substituents. Embedded image In the formula, R ₇ represents an alkyl group which may be substituted. R ₈ each independently represents an alkyl group, an alkenyl group, an alkoxy group, a sulfo group, or a halogen atom. When m is 2 or more, a plurality of R ₈ may be the same or different, and may be linked to each other to form a ring. Embedded image In the formula, R ₉ represents an optionally substituted alkyl group.