JPS6364776B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a direct positive silver halide color photographic material, more particularly a reflective especially reflective material having an unfogged internal latent image type blue-sensitive silver halide emulsion layer with improved speed, gradation, color balance and developability. Concerning multilayer direct positive color photographic materials suitable for reproduction from manuscripts. Furthermore, the present invention provides a multilayer halogen-based silver halide emulsion having a blue-sensitive silver halide emulsion layer that is useful for directly obtaining a positive by surface-developing an unfogged internal latent image type silver halide emulsion while exposing the entire surface to light during development. Concerning silver chemical positive color photographic materials. If a positive silver halide photographic material is used directly to reproduce monochrome or color photographs or reflective originals such as printed matter, a positive photographic image can be easily created directly without the hassle of reversal processing or creating an internegative. It is well known that it can be done. Internal latent image type positive emulsions generally have high sensitivity and are suitable for applications requiring high sensitivity, and various types of emulsions are already known in this technical field. However, the current situation is that the known emulsions still have insufficient performance and are difficult to put into practical use. That is, in order to perform mass replication on a practical scale, the following points must be overcome. Must be highly sensitive. Capable of developing in large quantities without processing fluctuations. A stable finish can be obtained without being affected by fluorescent agents, ultraviolet absorbers, etc. of the subject. etc. Various emulsion preparation methods have been proposed as techniques for increasing sensitivity, such as U.S. Pat.
Same No. 3761266, Same No. 3761276, Same No. 3796577,
It is described in British Patent No. 1151363, etc.
These techniques yield emulsions with relatively high sensitivity, but because these emulsion techniques mainly contain silver iodobromide, they have poor developability and lack processing stability during short-term high-temperature processing. There is. In other words, even if there are slight variations in processing conditions (e.g., temperature, time, stirring, developer activity, etc.), large fluctuations in the development effect occur, making it impossible to obtain stable and uniform development results. . On the other hand, core/shell type emulsions such as those disclosed in JP-A-55-127549 have relatively stable developability, but are insufficient in sensitivity, and higher sensitivity is desired. There are two known processing methods for directly obtaining a positive image using an internal latent image type silver halide photographic material: a method using a fogging agent and a light fogging method. Although the method of obtaining a positive image by adding a fogging agent such as a hydrazine compound to a color developing solution is simple, it has the following disadvantages, making it difficult to carry out large-scale development processing. cannot be said to be an appropriate method. In other words, a high alkali with a PH value of 12 or higher is required to bring out the effect of the fogging agent, and since the fogging agent is unstable in the developer, the fogging effect will be lost if it is left for half a day or a day after being added. Since this results in a significant decrease in the development effect, a stable developing effect cannot be expected. On the other hand, the optical fog method is a method in which a suitable light is irradiated during the development process to add fog and develop the surface, but the advantage of this method is that it is possible to use a normal color processing developer. , is more suitable for large-volume development processing than development using a fogging agent. However, when the developer is used, the developing agent is oxidized due to fatigue, air oxidation, etc., and the solution gradually becomes colored, which increases the degree of optical fog. Specifically, when the developing agent becomes oxidized, the developer becomes brown and absorbs blue light during photofogging, resulting in a decrease in the degree of fogging of the blue-sensitive layer and a decrease in the density obtained. The inventor has discovered that this results in variations in quality. In addition, it has become clear that when a large number of copies are made, the results vary widely depending on the type of subject being photographed (for example, printed matter, color or monochrome photographs, etc.). There are several possible causes for this, but the most common ones include fluorescent whitening agents, ultraviolet absorbers (these are used to stabilize the subject material, or to stabilize the dye), etc. There is. There are also several problems caused by the mechanisms used for copying, such as cameras and printers. For example, in order to obtain uniform brightness during copying, it is difficult to set the number and position of light sources, and it is especially difficult to fit them into a small, limited space.
Although it is relatively easy to obtain uniform brightness using a diffused light source, the amount of light decreases due to the diffuser plate, and the spectral energy distribution of the light source changes due to irregular absorption inside the wall surface, etc. This change is particularly strong in the blue light region, resulting in deterioration of color balance due to a decrease in sensitivity of the blue-sensitive silver halide layer of the light-sensitive material used. Furthermore, duplication using a camera or printer generally causes flare, resulting in a finish that is significantly softer than that produced by contact-based duplication, and higher gradation characteristics are required to obtain desirable reproduction prints. It became clear. Under these circumstances, there is a demand for the development of a direct-positive silver halide color photographic material suitable for copying mainly reflective originals, which has high sensitivity, high contrast, and excellent development stability. The first object of the present invention is to provide a color photographic material comprising an unfogged blue-sensitive internally latent image type silver halide having improved sensitivity, gradation and development stability, in particular a direct positive halogen film suitable for reproduction. Our objective is to provide silver oxide color photographic materials. A second object is to provide a direct positive silver halide color photographic material that has a stable color balance against changes in the spectral energy (especially blue light) of a light source during copying. Furthermore, the third objective is to form a positive image while imparting fogging by uniform exposure over the entire surface during color development, so that it has a fogging property that is not affected by the coloring of the processing agent. An object of the present invention is to provide a positive silver halide color photographic material. The purpose of the present invention is to have a photosensitive maximum wavelength of 465 to 495 nm.
The silver halide composition of the shell of the silver halide grains contained in the emulsion layer is AgBr _x Cl _y This is achieved with a direct positive color photographic material in which I _z x=100-y-Z (mol%) y≧75 (mol%) 0.5≧Z≧0 (mol%). The present invention will be described in detail below. The sensitizing dye used in the present invention may be one that exhibits a maximum photosensitive wavelength of 465 to 495 nm when added to the core/shell type internal latent image type silver halide used in the present invention, and more preferably a maximum photosensitive wavelength of 465 to 495 nm. is from 470
A wavelength of 490 nm is suitable and is not limited by the type of sensitizing dye. Sensitizing dyes with a maximum sensitivity wavelength shorter than 465 nm are difficult to notice the effects of sensitization or contrast enhancement, and
Sensitizing dyes longer than 495 nm increase sensitivity, but
Deterioration of color reproduction characteristics (for example, maximum photosensitive wavelength is 510 nm)
In this case, the color separation between blue and green deteriorates), making it unsuitable as a color photosensitive material. Therefore, even with the same sensitizing dye, the maximum sensitivity can vary depending on the properties of the silver halide (for example, silver halide composition, silver halide grain size, crystal habit, presence or absence of other additives, etc.), the amount of sensitizing dye added, and the method of addition. Since the wavelength varies somewhat, it is preferable to select the sensitizing dye experimentally. Specifically, Special Publication No. 45-19034, No. 46-14830
No. 46-30023, No. 48-42968, No. 50-
No. 37538, JP-A-49-11320, JP-A No. 51-14019,
No. 51-29128, No. 51-29129, No. 51-30724,
The sensitizing dyes can be selected from among the sensitizing dyes described in Publications No. 51-80224, US Pat. No. 3,752,670, etc., and two or more types can be used in combination if necessary. Specific examples of sensitizing dyes used in the present invention are shown below. However, the scope of the present invention is not limited to these sensitizing dyes. General formula [] In the formula, Z and Z' represent an atomic group necessary to form a nucleus of quinoline, benzoxazole, benzothiazole, benzoselenazole, benzimidazole, naphthoxazole, naphthothiazole, naphthoselenazole, naphthoimidazole, etc. R and R' are an alkyl group having 1 to 15 carbon atoms, a substituted alkyl group, or an aralkyl group (for example, a methyl group,
(ethyl group, heptyl group, hydroxyethyl group, sulfobutyl group, carboxyethyl group, etc.). X ₁ represents an acid anion (eg, halogen ion, methyl sulfate ion, p-toluenesulfonate ion, etc.) that forms a salt with the ammonium cation of the basic cyanine nucleus. m represents 0 or 1. Specific examples of compounds represented by the general formula [] are shown below. General formula [] In the formula, Z ₄ is a 5-membered or 6-membered heterocyclic nucleus (e.g. oxazole, thiazole, selenazole, benzoxazole, benzothiazole, benzoselenazole, naphthoxazole, naphthothiazole, naphthoselenazole, thiazoline, pyridine, quinoline) , 3,3-dialkylindolenine, etc.). Z ₅ is an oxygen atom, sulfur atom, selenium atom or N
-R ₄ (R ₄ represents an alkyl group or an aryl group.
These may be substituted. ). R ₁ , R ₂ and R ₃ each represent an optionally substituted lower alkyl group, an aralkyl group, an aryl group, or the like. (For example, methyl group, ethyl group, sulfoethyl group, sulfobutyl group, carboxymethyl group,
hydroxyethyl group, benzyl group, phenyl group, etc.) d represents 0 or 1. Specific compounds represented by the general formula [] are shown below. General formula [] In the formula, R ₅ is an alkyl group having 1 to 6 carbon atoms, a sulfoalkyl group, a carboxyalkyl group, a hydroxyalkyl group, etc. (for example, -CH ₃ , -C ₂ H ₅ , -
(CH ₂ ) ₃ SO ₃ Na, -CH ₃ COOH, -C ₂ H ₅ OH, etc.). R ₆ and R ₇ are alkyl groups having 1 to 6 carbon atoms, substituted alkyl groups, aralkyl groups, aryl groups, substituted aryl groups, etc. (for example, -CH ₃ , -C ₂ H ₅ , -
C ₂ H ₅ SO ₃ H, ―C ₂ H ₅ SO ₃ Na, ―CH ₃ COOH, ―
_{C2H5OH ,}

【formula】

【formula】

[Formula] etc.) is shown. Z represents a sulfur atom or a selenium atom. Examples of compounds represented by the general formula [] are shown below. These blue-sensitizing dyes are described, for example, in "The Chemistry of Heterocyclic Compounds" by F.M. Harmer.
Chemistry of Heterocyclic Compounds) No. 18
Volume and "The Cyanine Dye and Related Compound"
Related Compounds; A Weissberger ed.
It can be easily synthesized according to the method described in Interscience, New York, 1964). In addition, in order to incorporate these blue-sensitizing dyes into a silver halide emulsion, silver halide is dissolved in a single or mixed solvent of various organic solvents such as water, methanol, acetone, etc. It can be added during any process from the formation, growth or physical ripening of grain nuclei to just before coating the emulsion. The amount used at this time may be at a concentration commonly used in this technical field, or may be used at a high concentration that would normally cause a desensitizing effect when a known emulsion is used. good. The amount of the sensitizing dye used in the present invention having a maximum photosensitive wavelength of 465 to 495 nm is about 1.0 x 10 ^-5 to about 1 x 10 ^-3 mol, preferably 4 x 10 ^-5 to 5 mol, per mol of silver halide. It may be used at an addition concentration of ×10 ⁻⁴ mol. In addition to the sensitizing dye of the present invention, there are
There is no problem even if a sensitizing dye of 465 nm or less is used in combination. The direct positive color photographic material of the present invention requires green and red sensitive layers in addition to the blue sensitive layer described above,
In addition, an undercoat layer, an intermediate layer, an ultraviolet absorbing layer, an antihalation layer, a colored (mainly yellow) filter layer, and a protective layer may be included as required. The preferred sensitivity wavelength range for green-sensitive emulsions is 500~
570nm, and the preferable maximum photosensitive wavelength is 540~
It is 560nm. Further, the preferable photosensitive wavelength range of the red-sensitive emulsion is 600 to 680 nm, and the preferable photosensitive maximum wavelength is 650 to 670 nm. Note that it is effective for the red-sensitive emulsion to have as little photosensitivity as possible to green light in order to obtain preferable color reproduction. The above-mentioned green-sensitive emulsion and red-sensitive emulsion are each optically sensitized using a suitable sensitizing dye to impart photosensitivity to a desired wavelength range. Sensitizing dyes used include methine dyes and sulityl dyes such as cyanine, merocyanine, hemicyanine, rhodacyanine, oxonol, and hemioxonol. Further, each of the sensitizing dyes may be used alone or in combination of two or more. Specific examples include JP-B No. 46-549, JP-A No. 50-40662, and JP-A-47.
-26126, 48-33817, 48-41733, 48-33817, 48-41733,
It is a green-sensitizing dye described in publications such as No. 48-59828 and US Pat. No. 2,177,402. Mata Tokuko Showa 43-4938
No. 48-42974, JP-A-49-106322, No. 49
It is a red-sensitizing dye described in No. 111629 and No. 48-56426. The core/shell type internal latent image type silver halide emulsion used in the present invention is one in which the silver halide grains contained in the emulsion consist essentially of core/shell type internal latent image type silver halide grains. , the silver halide composition of the shell portion of the emulsion contains 75 mol % or more of silver chloride and 0.5 to 0 mol % of silver iodide. Further, the composition of the silver halide in the core portion preferably contains 65 mol% or more of silver bromide and 1 mol% or less of silver iodide, and more preferably 75 mol% or more of silver bromide and 0.5 mol%. It contains the following silver iodide. The molar ratio of the core to the shell is preferably about 70/30 to 60/40 because it provides high stability during development. Furthermore, the composition of the total silver halide is 30 to 40 mol% silver chloride and silver bromide.
Silver chlorobromoiodide containing 70 to 60 mol% and silver iodide of 0.6 mol% or less is optimal. An internal latent image type silver halide emulsion is defined as the maximum density when a coated test piece is exposed for an exposure time of 1 second to 1/1000 second, and then developed for 3 minutes at 20°C with the following internal developer. The emulsion is at least 5 times, preferably more than 10 times, the maximum density when developed with the following surface developer at 20° C. for 4 minutes. Internal developer Hydroquinone 15g N-methyl-p-aminophenol sulfate
15g Sodium sulfite (anhydrous) 50g Potassium bromide 10g Sodium hydroxide 25g Sodium thiosulfate (crystal) 20g Add water 1 Surface developer p-hydroxyphenylglycine 10g Sodium carbonate (crystal) 100g Add water 1 bottle The emulsion of the invention contains commonly used stabilizers, such as compounds having an azaindene ring and heterocyclic compounds having a mercapto group, in order to keep the surface sensitivity as low as possible and to impart lower minimum density and more stable properties. can be done. Compounds with an azaindene ring include 4-
Hydroxy-6-methyl-1,3,3a,7-tetrazaindene is preferred. Examples of the nitrogen-containing heterocyclic compound having a mercapto group include a pyrazole ring,
1,2,4-triazole ring, 1,2,3-triazole ring, 1,3,4-thiadiazole ring,
1,2,3-thiadiazole ring, 1,2,4-thiadiazole ring, 1,2,5-thiadiazole ring, 1,2,3,4-tetrazole ring, pyridazine ring, 1,2,3-triazine ring, 1, 2, 4-
Triazine ring, 1,3,5-triazine ring, rings in which 2 to 3 of these rings are condensed, such as triazolotriazole ring, diazaindene ring, triazaindene ring, tetrazaindene ring, pentazaindene ring, etc. Examples include a phthalazinone ring and an indazole ring, but 1-phenyl-5-mercaptotetrazole is preferred. Various photographic additives may optionally be added to the internal latent image type silver halide emulsion according to the present invention. In addition, in the present invention, additives used depending on the purpose include wetting agents such as dihydroxyalkanes, and film property improvers such as alkyl acrylate or alkyl methacrylate and acrylic acid or Water-dispersible fine particulate polymeric substances obtained by emulsion polymerization such as copolymers with methacrylic acid, styrene-maleic acid copolymers, and styrene-maleic anhydride half-alkyl ester copolymers are suitable. Examples of coating aids include saponin and polyethylene glycol lauryl ether. Other photographic additives include gelatin plasticizers, surfactants, ultraviolet absorbers, PH regulators, antioxidants, antistatic agents, thickeners, graininess improvers, dyes, mordants, brighteners, and development speed. The use of conditioning agents, matting agents, anti-irradiation dyes, etc. is optional. In the color photographic materials of the invention, it is preferred to use dye-forming couplers that can be incorporated into the silver halide emulsion. Useful yellow dye-forming couplers include benzoylacetanilide type, pivaloylacetanilide type, and two-equivalent type yellow couplers in which the carbon atom at the coupling position is substituted with a so-called split-off group that can be separated during coupling. As the magenta dye-forming coupler, a 5-pyrazolone type, pyrazolotriazole type, pyrazolinobenzimidazole type, indazolone type, or a two-equivalent type magenta coupler having a split-off group is useful. As cyan dye-forming couplers, phenolic, naphthol, pyrazoquinazolone, or two-equivalent cyan couplers having a split-off group are useful. These dye-forming couplers can be selected arbitrarily;
Moreover, there are no particular limitations on the method of use, the amount used, etc. The photographic emulsion of the present invention is combined with a color image-providing material for diffusion transfer that releases a diffusible dye in response to development of silver halide to obtain a desired transferred image on an image-receiving material after an appropriate development process. It can also be used for. Examples of such color image-providing materials for diffusion transfer include US Pat. No. 3,227,551, US Pat.
No. 3443939, No. 3443940, No. 3658824, No. 3698897,
No. 3725062, No. 3728113, No. 3751406, British patents
No. 840781, No. 904364, No. 1038331, OLS No. 1930215, No. 2214381, No. 2228361,
No. 2242762, No. 2317134, No. 2402900, No. 2406626,
Those described in No. 2406653, JP-A-49-114424, etc. can be used. In addition, it is useful to use ultraviolet absorbers such as thiazolidone, benzotriazole, acrylonitrile, and benzophenone compounds to prevent color fading of dye images due to short-wavelength actinic rays. 326, same
It is advantageous to use 327 and 328 (both manufactured by Ciba Geigy) alone or in combination. In addition to gelatin, the silver halide color photographic material according to the present invention may contain a suitable gelatin derivative depending on the purpose. Examples of suitable gelatin derivatives include acylated gelatin, guanidylated gelatin, carbamylated gelatin, cyanoethanolated gelatin, and esterified gelatin. Further, in the present invention, other hydrophilic binders commonly used in silver halide emulsions may be included depending on the purpose.
Furthermore, the binder may contain a suitable plasticizer, lubricant, etc. depending on the purpose. Any support can be used for the direct positive color photographic material according to the present invention, but typical supports include polyethylene terephthalate film, polycarbonate film, polystyrene film, polypropylene film, which has been subbed as required. cellulose acetate film,
Includes glass, baryta paper, polyethylene laminate paper, etc. Note that a support that has been treated to make it white and opaque is particularly useful as a support in the present invention. With the color photographic material of the present invention, a positive image can be easily obtained directly by subjecting the material to surface development after photographing in a conventional manner. That is, the main step of directly forming a positive image consists of surface development of the uncoupled internal latent image type silver halide photosensitive material of the present invention while subjecting it to fogging treatment after image exposure. The fogging treatment can be carried out by exposing the entire surface to light or by using a fogging agent. In the present invention, the entire surface exposure is carried out by immersing or moistening the image-exposed photosensitive material in a developer and then uniformly exposing the entire surface to light. The light source used here may be any light as long as it has spectral energy over the sensitive wavelength range of the photographic material of the present invention, and high-intensity light such as flash light may be applied for a short time, or it may be a weak light source. You can expose it to light for a long time. Further, the overall exposure time can be varied over a wide range depending on the photosensitive material development processing conditions, the type of light source used, etc. so as to ultimately obtain the best positive image. The surface development treatment method means treatment with a developer substantially free of silver halide solvent. Color developing agents that can be used in the developer used in the photographic material of the present invention include:
N,N-diethylparaphenylenediamine, N-
Ethyl-N-(β-hydroxyethyl)paraphenylenediamine, 4-amino-N-ethyl-N-
(β-methanesulfonamidoethyl) metatoluidine, 4-amino-N-ethyl-N-(β-hydroxyethyl) metatoluidine, 4-amino-N
-ethyl-N-(β-methoxyethyl) metatoluidine, 4-amino-N-ethyl-N-(β-ethoxyethyl) metatoluidine, 4-amino-N
Examples thereof include -ethyl-N-{β-(β-ethoxy)ethoxyethyl} metatoluidine and their salts with organic or inorganic acids. These developers can also be included in the emulsion in advance and allowed to act on the silver halide during immersion in a high pH aqueous solution. The developer used in the photographic material of the present invention may further contain specific antifoggants and development inhibitors, or these developer additives may be optionally added to the layer of the silver halide photographic light-sensitive material. It is also possible to incorporate it into Commonly useful antifoggants include benzotriazoles such as 5-methylbenzotriazole, benzimidazoles, benzothiazoles, benzoxazoles, heterocyclic thiones such as 1-phenyl-5-mercaptotetrazole, aromatic and aliphatic mercapto compounds. It may also contain a development accelerator such as a polyalkylene oxide derivative or a quaternary ammonium salt compound. Other commonly used preservatives, alkaline agents,
It is also possible to contain a PH adjuster and the like. The present invention will be illustrated below with reference to Examples, but the embodiments of the present invention are not limited thereto. The development treatment in the examples is carried out by the following method. Color developer composition Potassium carbonate 28.9g Potassium sulfite 2.6g Sodium bromide 0.26g Benzyl alcohol 12.8g Ethylene glycol 3.4g Hydroxylamine sulfate 2.6g Diaminopropanoltetraacetic acid 0.09g Sodium chloride 3.2g Nitrilotriacetic acid 0.4g 3-Methyl-4 -amino-N-ethyl-N-
(β-methanesulfonamidoethyl)-aniline sulfate 4.25g Add water 1 PH (adjusted with potassium hydroxide) 10.20 Bleach-fix solution composition Ammonium thiosulfate 110g Sodium bisulfite 10g Iron ammonium ethylenediaminetetraacetate
60g Diammonium ethylenediaminetetraacetate
Add 5g bisthiourea 2g water 1PH (adjusted with aqueous ammonia) 6.5 Image exposure: Xenon light was irradiated using a stepped wedge with a density difference of 0.15. Development process Color development: 38℃ 2 minutes 30 seconds (after 10 seconds of immersion in the solution)
Perform light fog exposure of 10 CMS *) Bleach fixing: 38℃ 1 minute 30 seconds Washing with water: 30 to 38℃ 1 minute 30 seconds Drying: 65℃ 1 minute *Light fog exposure: White acrylic plate using white fluorescent light as the light source Attenuation and uniform light irradiation were performed using a neutral filter. Concentration measurement: Sakura photoelectric densitometer PDA-65 was used. However, the zero point was aligned with the surface of the support used. γ: Average gamma (tanα) at density 0.5 to 1.5 Sensitivity: Reciprocal of relative light amount (CMS) that provides density D=1.0. Measurement of spectral sensitivity: Image exposure was carried out using a grating type spectrophotometer (type TY-GR-2, manufactured by Narumi Shokai Co., Ltd.), and development was carried out in the usual manner. For the purposes of the present invention, the photographic properties (sensitivity, gradation (gamma), maximum density, minimum density, and maximum wavelength of sensitivity) in the examples are expressed by blue density measurement values indicating the values of the blue-sensitive emulsion layer. Example 1 An internal latent image type emulsion was prepared by the following method.
Preparation of core emulsion: While controlling the emulsification and ripening temperature to 60°C, emulsify by simultaneously injecting 175 ml of a 2 molar silver nitrate aqueous solution and 175 ml of a 2.1 molar potassium chloride aqueous solution into an aqueous solution containing 10 g of gelatin over 30 minutes. Mixed. After aging for 10 minutes, a 2 molar potassium bromide aqueous solution and a 1.0 molar potassium iodide aqueous solution were added over 1 minute in the amounts shown in Table 1, and the mixture was further aged for 10 minutes. Then, the temperature was lowered to 40° C., the silver halide was separated from the aqueous layer by adding magnesium sulfate, and the water-soluble salts were removed by a conventional precipitation washing method including decantation. Next, add 5g of gelatin and dissolve the entire amount.
The volume was 500ml.

[Table] The size of the silver halide was 0.55 to 0.58μ. Shelling was performed on each core emulsion in the following manner to obtain a layered internal latent image emulsion. While keeping 500ml of the core emulsion at 50℃, add silver nitrate,
Prepare an aqueous solution of potassium chloride and potassium bromide with a 1 molar concentration each, and an aqueous solution of potassium iodide with a 0.1 molar concentration, and add the silver nitrate solution and the halogen solution in the amounts listed in Table 2 over 5 minutes using a metering pump. The mixture was divided into two parts and simultaneously injected, aged for 10 minutes, washed with water for precipitation as described above, and after removing excess water-soluble salts, 20 g of gelatin was added to make the total volume 500 ml each.

[Table] The feature of the present invention is the blue-sensitive layer, and a specific method for producing a multilayer color photographic material using red and green light-sensitive layers and an intermediate layer in addition to the blue-sensitive layer will be described below. (1) Red light-sensitive layer The core emulsion described above was prepared in the same manner as core A except that the emulsification mixing time was 5 minutes, and the shell was prepared in the same manner as K. Furthermore, the following sensitizing dyes [] and [], stabilizers [] and cyan color dispersion []

[Table] Dissolved in ethyl acetate and dioctyl phthalate and protected and dispersed in sodium dodecylbenzenesulfonate and gelatin solution. was added to the emulsion using a conventional method, and an appropriate amount of gelatin was added to obtain a silver amount of 5 mg and a gelatin amount of 25 mg/dm ^{2 .}
Apply it so that (2) Intermediate layer Coat 0.5 mg of gray colloidal silver, 4 mg of 2,5-di-tert-octylhydroquinone protected and dispersed by ultrasonic waves, and 10 mg/dm ² of gelatin. (3) Green light-sensitive layer The following sensitizing dye [] and [] stabilizer [], magenta coupler dispersion [] and hardener [] were added to the same core/shell emulsion as used for the red light-sensitive layer. Add gelatin according to the method and apply so that the amount of silver is 4 mg and the amount of gelatin is 20 mg/dm ² .

[Table] Dissolved in ethyl acetate and dioctyl phthalate and protected and dispersed in sodium dodecylbenzenesulfonate and gelatin solution using ultrasonic waves. [] Add at a rate of 0.02mg per 1g of bis(vinylsulfonylmethyl)ether gelatin. (4) Yellow filter layer Coat by adding 1.5 mg of colloidal silver, 4 mg of 2,5-di-tert-octylhydroquinone protected and dispersed by ultrasonic waves, and a coating aid to make gelatin 10 mg/dm ² . (5) Blue light sensitive layer This will be explained separately. (6) Protective layer: 15mg of gelatin, 0.6mg of the above-mentioned hardener []
Coat by adding a coating aid so that the amount is mg/dm ² . (5) Blue light sensitive layer Shelling was performed on each of cores A, B, C, D and E by method L. To the emulsion thus prepared (listed in Table 3), sensitizing dye-6 or comparison-1 was prepared with and without the addition of 4×10 ^-4 mol of each, and in addition, 500 mg of stabilizer,
Add yellow coupler dispersion [], hardener [] coating aid, and appropriate amount of gelatin to reduce the amount of silver to 6.
The amount of gelatin was applied at 20 mg/dm ² . Comparison-1 [] Yellow coupler dispersion α-[4-(1-benzyl-2-phenyl-
3,5-dioxo-1,2,4-triazolidinyl)]-α-pivalyl-2-chloro-5
-[γ-(2,4-di-tert-amylphenoxy)butyramide]acetanilide 80g 2,5-di-tert-octylhydroquinone
1g Chinuvin 328 (manufactured by Ciba Geigy) 10g Tinuvin 120 ( ) 10g The above four types were mixed with ethyl acetate, dioctyl phthalate,
It was dissolved in dibutyl phthalate, added to a gelatin solution containing sodium dodecylbenzenesulfonate, and subjected to protective dispersion using ultrasonic waves. Apply 220 μl of the coating solution (1) to (6) thus prepared.
Samples were prepared by sequentially coating thick polyethylene coated paper. This sample was developed according to the method described above, and the sensitivity, maximum wavelength of exposure, maximum density, and minimum density were measured. The results are shown in Table-3. Note that sensitivity is expressed as relative sensitivity.

【table】

[Table] As seen in Table 3, the sensitization ratio is higher in the samples to which the sensitizing dye is added, but the samples according to the present invention (those to which -6 is added) have an even higher sensitization ratio than the comparison -1. It is clear that this shows the sensitivity ratio. Furthermore, as the molar ratio of silver chloride in the core increases, the sensitivity decreases, but in the case of the samples of the present invention, the degree of this decrease is small, and it will be understood that the sensitizing dye is effective.
Furthermore, as the silver iodide molar ratio of the core increases, the sensitivity increases, but the maximum density and γ decrease significantly, making it impractical. It was also observed that the density decreased when the color development time was shortened or that desilvering was insufficient when the bleach-fixing period was shortened. From the above, the composition of the core emulsion is silver bromide.
It will be appreciated that silver chlorobromoiodide containing at least 60 mole percent and less than 1 mole percent silver iodide is preferred. Example 2 Next, it will be shown that the silver halide composition of the shell has a great effect on photographic performance, and that a shell containing silver chloride as a main component is effective. A blue-sensitive core/shell emulsion was prepared as shown in Table 4 in the same manner as in Example 1, except for the same procedure as in Example 1.
I made it to be the same as. A was used for the core. The results are shown in Table-4.

[Table] From Table 4, it is understood that those with a higher silver chloride ratio have higher density and γ and exhibit better photographic properties, and furthermore, the samples using the sensitizing dye of the present invention have higher sensitivity. . The silver iodide content is limited to 0.5 mol%,
It can be understood from this that as the content increases, the decrease in γ and concentration increases, making it less practical. In addition, the silver halide composition of the shell emulsion is silver chloride.
It can be seen that silver chlorobromoiodide with a content of 75 mol% or more and a silver iodide content of 0.5 mol% or less is optimal. Example 3 It is shown that the maximum sensitivity wavelength of a sensitizing dye affects sensitivity and γ. Example 2 was carried out in the same manner as in Example 2, except that the sensitizing dye of the present invention and the comparative sensitizing dye were added to the core/shell (according to A/K) emulsion used in Example 2 in the amounts shown in Table 5. A sample was prepared. Comparison-1 Comparison-2

【table】

[Table] As is clear from Table 5, the sample of the present invention has high sensitivity and high contrast. Embodiment 4 Next, the influence of changes in the spectral energy of the light source during photographing will be explained. Using the sample used in Example-3, copies were made using a Sakura photocopier IDC-9210 (manufactured by Konishiroku Photo Industry Co., Ltd.). At this time, a gray reflective original was copied in order to see the substantial change in sensitivity between a new product and a used product (the inner wall surface was dirty after being used for three years). In addition, the spectral reflectance of the inner wall surface is
As shown in the figure. Table 6: Yellow positive images were measured using tone reproduction curves obtained by developing each sample.
It became like that. We also measured the difference in aperture when photographing using a color correction filter to correct for gray.

[Table] According to this, the sensitivity and Y of the present invention are high;
Also, the sensitivity of a practical camera is equivalent to about 1/2 aperture (approx.
50%) and that there is little deterioration in sensitivity between new and used photographic devices, and the effectiveness of the present invention can be clearly understood. Example 5 The effectiveness of the developer against coloring during development processing will be explained. It is already well known that when a developer is used for a long period of time, it becomes colored brown due to the oxidized product of the developing agent and other factors. It will become clear that there is. While processing a large amount of sensitive material while replenishing the developer, the degree of coloration of the developer was measured using a spectrophotometer (measurement wavelength: 435 nm) and the sample was developed. The development process was carried out in accordance with Example 1, and the depth of immersion of the sample in the developer was 10 mm from the surface. A point corresponding to a composite gray chart density of 1.5 treated with the new solution was compared with that point treated with the colored developer, and the difference in density was determined and shown in Table 7.

[Table] As is clear from Table 7, it was found that the samples of the present invention showed a small decrease in color density even with the filter effect on blue light due to the coloring of the developer and had a good color density balance. This characteristic is particularly effective when the developing process is automated by a machine, and is an important factor in obtaining safe results against fluctuations in the optical fogging effect due to changes in the processing solution.

[Brief explanation of drawings]

FIG. 1 is a graph showing the spectral reflectance of the inner wall surface of the photocopier used in the example.

Claims (1)

[Scope of Claims] 1. A blue-sensitive core/shell type internal latent image type silver halide emulsion layer containing a sensitizing dye having a maximum photosensitive wavelength of 465 to 495 nm, and a silver halide contained in the emulsion. A direct method characterized in that the silver halide composition of the shell of the grain is AgBr _x Cl _y I _z Positive color photographic material.