JPS6115421B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to improvements in light-sensitive silver halide color photographic emulsions containing hydrophobic cyan dye-forming couplers, and more specifically, silver halide colors containing at least two hydrophobic phenolic cyan dye-forming couplers with specific structures. It concerns photographic emulsions. In silver halide color photographic materials,
Usually, a support has silver halide selectively sensitized to form development nuclei upon exposure to blue light, green light, and red light, and includes a blue-sensitive emulsion layer and a green-sensitive emulsion layer. and a red light-sensitive emulsion layer. When such a color photographic light-sensitive material is exposed and then treated with a developer containing a color developing agent, the color developing agent reduces silver halide having development nuclei into developed silver and is itself oxidized. The oxidation product and coupler react to form a dye. Next, the developed silver is desilvered by bleaching and fixing, and the remaining silver halide without development nuclei is fixed to obtain a dye image. In this method, subtractive color reproduction is usually used for color reproduction, and in order to form yellow, magenta, and cyan color images, which are complementary colors to blue, green, and red, respectively, a yellow coupler is used in the blue-sensitive emulsion layer, and a yellow coupler is used in the blue-sensitive emulsion layer. The photosensitive emulsion layer contains a magenta coupler, and the red photosensitive emulsion layer contains a cyan coupler. Methods for incorporating couplers into silver halide color photographic light-sensitive materials include a water-dissolving method in which a coupler having a hydrophilic group in its skeleton structure is dissolved in water or an alkaline solution and added to a silver halide emulsion; A hydrophobic coupler with a lipophilic group introduced into its skeleton structure is dissolved in an organic solvent that is sparingly soluble or insoluble in water, and dispersed into minute oil droplet particles in an aqueous solution containing a surfactant and a hydrophilic protective colloid. There are two methods: an oil-soluble method in which it is added to a silveride emulsion. However, the oil-soluble method does not have the negative effect of stagnation and thickening, and it is easy to obtain a uniform coating film thickness.The coupler and the dye produced by the color development process are wrapped in an organic solvent, and are free from water and surrounding substances. Protected, the coupler and coloring dye have good stability over time, and since the coupler exists in an amorphous form as oil droplet particles, light absorption is sharp and the image has excellent sharpness and graininess. There are advantages. Therefore, this method is mostly adopted in the photography industry. However, hydrophobic couplers used in oil-soluble methods are required to have the following properties. (1) A highly pure coupler can be obtained by a simple synthesis method from readily available and inexpensive raw materials. (2) The coupler and the coloring dye produced by color development are well soluble in high boiling point organic solvents such as dibutyl phthalate and tricresyl phosphate, and a highly concentrated solution can be obtained. (3) After adding a coupler oil droplet dispersion to a silver halide emulsion, a stable coating film can be obtained without crystallization even after coating and drying on a support. (4) It should not have any adverse effect on the silver halide emulsion. (5) Good color development, transparency of color dye images, and excellent spectral absorption characteristics. (6) Colored dye images must be robust to heat, light, and humidity. Many proposals have been made to improve these points. Cyan dye-forming couplers, especially phenolic cyan couplers that are often used in photographic paper, have good coloring properties, excellent spectral absorption, and can provide desirable hues.
The following couplers (1) and (2) described in Specifications No. 2725291 and No. 2801171 are mentioned. However, these couplers have poor color fastness to heat and humidity, and the stability of the silver halide emulsion after being dispersed by an oil-soluble method and added to the silver halide emulsion, that is, oil droplet-dispersed particles. There is a problem that the stability over time is poor. As a method for increasing the fastness of coloring dyes against heat and humidity, a method has been proposed in which a hydrophobic antifading agent, such as an ultraviolet absorbing compound, is dispersed in oil droplets at the same time as a cyan coupler. However, in this method, it is necessary to add at least 10% by weight of the antifading agent to the coupler, and because the amount added is large, the stability of the oil droplets dispersed in the silver halide emulsion decreases, causing crystallization. It becomes easier. Further, there is a problem that crystals may precipitate during emulsification dispersion using a homogenizer or the like or during storage after emulsification and dispersion. As a method of increasing the stability of oil droplet-dispersed particles, it is possible to use a large amount of high-boiling point solvents such as tricresyl phosphate or dibutyl phthalate, or to use a large amount of high-boiling point solvents and to add surfactants, hydrophilic colloids, etc. It is known to be used in increasing amounts. However, this method increases the coating thickness and increases the tendency of the photographic material to curl. The permeability of the developing solution deteriorates, resulting in a decrease in color development. As the film becomes thicker, there are problems such as increased light scattering within the film layer, lowering the sharpness of the image, worsening the color uniformity, and increasing the amount of chemicals used. In addition, various methods have been proposed by improving coupler solvents, surfactants, etc., but none of them are currently satisfactory. Furthermore, as an improvement method using couplers, a method is known in which a long-chain alkyl group is introduced in order to increase lipophilicity by a hydrophobic group bonded to the skeletal structure of the coupler. This method increases the solubility in high boiling point solvents and stabilizes the oil droplet dispersed particles, but on the other hand, the molecular weight of the coupler increases,
In order to obtain the same color density, it is necessary to increase the amount of coupler added, and accordingly, the amount of solvent and protective colloid also need to be increased, resulting in less effective results. . The present invention has been made to solve the above problems. The first object is to provide a silver halide color photographic emulsion which has improved storage stability and stability of oil droplet dispersed particles of a hydrophobic cyan coupler contained in the silver halide color photographic emulsion. A second object is to provide a silver halide color photographic emulsion which can be obtained by reducing the amount of coupler solvent used, making the emulsion film thinner, and improving physical properties such as permeability of processing liquids. A third object of the invention is to provide a silver halide color photographic emulsion from which images having excellent fastness to heat and humidity can be obtained. As a result of repeated research to achieve the above object, the present inventors have found that the object can be achieved by using at least two types of hydrophobic phenol couplers represented by the following general formula [] dispersed in oil droplets. The present invention was completed. General formula [] (In the formula, R ₁ represents a hydrogen atom, a methyl group or an ethyl group, n represents an integer of 0 to 2, R ₂ and R ₃ represent a hydrogen atom, an alkyl group or an alkoxy group, provided that R ₂ and R ₃ (The total number of carbon atoms is 8 to 15.) It has been known that two or more types of couplers can be used in combination to achieve various purposes. For example, (1) a method of adjusting spectral absorption characteristics by using a combination of a phenolic cyan coupler and a naphthol type cyan coupler, which have different spectral absorption characteristics (for example, see Japanese Patent Publication No. 1983-6993); (2) color negative film; A method for correcting defects in color reproduction by using a colored coupler and a cyan coupler together with an automatic masking mechanism (e.g., U.S. Patent No.
(See the specifications of No. 2449966, No. 2455169, No. 2521908, No. 3034872, and No. 4004929), (3)
Combinations with development inhibitor-releasing couplers, (4) combinations of water-soluble couplers and hydrophobic couplers, etc. are known. Conventional techniques for using these couplers in combination include using couplers with different performances to complement each other, or using couplers with special performance together to achieve that performance. be. However, when the present inventors used two or more couplers represented by the above general formula [] in combination, they surprisingly found that dibutyl phthalate and tricresyl It has been found that the solubility in solvents such as phosphates is improved, and in particular, the stability of coupler particles dispersed in oil droplets is significantly improved. The use of two or more couplers in combination for stabilizing the oil droplet-dispersed particles of the coupler was completely unknown not only for cyan couplers but also for magenta couplers and yellow couplers. By using two or more couplers represented by the general formula [] in the present invention, the solubility in dibutyl phthalate, tricresyl phosphate, etc. is improved, and the dispersed oil droplet particles of the coupler are stabilized. Therefore, it is possible to increase the amount of a hydrophobic antifading agent such as an ultraviolet absorbing compound, which conventionally had to be added in a reduced amount, and to obtain a color photographic material with excellent fastness of a cyan dye image. Furthermore, since the amount of the coupler solvent can be reduced, the thickness of the coating film can be reduced, thereby improving the physical properties against curling etc. and improving the permeability of the processing liquid. Furthermore, excellent effects such as improved sharpness of dye images obtained by color development processing can be achieved. Next, typical cyan couplers represented by the general formula [] used in the present invention are shown.
However, it is not limited to this. These cyan couplers are disclosed in, for example, U.S. Pat.
It can be easily synthesized by the method described in Japanese Patent Publication No. 44-3660 and Japanese Patent Publication No. 51-40804. The mixing ratio of these two cyan couplers is 5 to 95 mol% for one and 95 to 5 mol% for the other, and the preferred ratio is 20 to 80 mol% for one and 80 to 20 mol% for the other. . The effect can be obtained by mixing two or more couplers represented by the general formula [], but the most effective ones are those whose structures are similar to those of the couplers to be mixed, and the specific Specifically, a mixture of the three types (C-1), (C-2) and (C-3) is particularly preferred. A drawback of the coupler represented by the general formula [] used in the present invention is that the fastness of the coloring dye image to heat and humidity is poor. Therefore, it is preferable to use anti-fading agents as shown in the following general formulas [] and [] in combination. General formula [] (In the formula, R ₄ is a hydrogen atom, an alkyl group (e.g., methyl, ethyl, n-propyl, isopropyl, aminopropyl, n-butyl, sec-butyl, tert
-butyl, chlorobutyl, n-amyl, isoamyl, hexyl, octyl, nonyl, stearylamide butyl, decyl, dodecyl, pentadecyl,
hexadecyl, cyclohexyl, benzyl, phenylethyl, phenylpropyl, etc.), alkenyl groups (e.g., vinyl, allyl, metaallyl, dotecenyl, tridecenyl, tetradecenyl, octadecenyl, etc.), aryl groups (e.g., phenyl, 4-methylphenyl, 4-ethoxyphenyl, etc.), enyl, 2-hexoxyphenyl, 3-hexoxyphenyl, etc.), acyl groups (e.g., acetyl, propionyl, ethoxycarbonylbutyroyl, hexanoyl, octanoyl, acetoacetyl,
-butenoyl, butoxypropionyl, phenylacetyl, etc.), alkyl or arylsulfonyl groups (methanesulfonyl, ethylsulfonyl,
(benzenesulfonyl, toluenesulfonyl, etc.), N-substituted carbamoyl group or sulfamoyl group, substituted or unsubstituted alkyl group, aryl group, alkoxy group or aryloxy group, oxalyl group, oxamoyl group, oxycarbonyl, oxalacetyl group. represent _R5 , _R6 ,
R ₇ , R ₈ and R ₉ may be the same or different, and include a hydrogen atom, a halogen atom (fluorine, chlorine, bromine, iodine), a nitro group, a hydroxyl group, an alkyl group,
alkenyl group, aryl group, alkoxy group, acyloxy group, aryloxy group, alkylthio group, arylthio group, mono- or dialkylamino group or 5- or 6-membered heterocyclic group containing oxygen or nitrogen (e.g. piperidino, morpholino, pyrrolidino, piperazino, etc.), R ₈ and R ₉
may be closed to form a 5- or 6-membered ring consisting of carbon atoms. General formula [] [In the formula, R ₁₀ represents an n-valent organic group, such as an unsubstituted alkyl group (which may be linear, branched, alicyclic, or unsaturated, and preferably has 20 or less carbon atoms. For example, methyl, ethyl, propyl, octyl, dodecyl, hexadecyl, ethylene, trimethylene, propylene, hexamethylene, glyceryl, cyclohexyl, allyl, butenediyl, etc.), substituted alkyl groups (such as alkoxyalkyl, halogenated alkyl, cyclohexanedimethyl, benzyl, phenethyl, etc.) ) or an aryl group (e.g. phenyl, alkyl-substituted phenyl, halogenated phenyl, o-, m- or p-
phenylenechloroglycylpyrocatechyl, etc.), and R ₁₁ and R ₁₂ each represent a substituted or unsubstituted alkyl group (which may be linear, branched, alicyclic, or unsaturated, preferably carbon For example, methyl, ethyl, propyl, butyl, amyl, hexyl, pentyl, amyl, octyl, benzyl, phenethyl, cyclopentyl,
cyclohexyl, etc.), and n represents an integer from 1 to 6. Examples of particularly useful compounds represented by the above general formula [] or [] are shown below, but of course the compounds are not limited thereto. The compounds represented by the general formulas [] and [] are known as ultraviolet absorbers, and are disclosed in British Patent No. 879144, US Patent No. 3042669, and US Patent No. 3042669.
No. 3112338, No. 3168492, No. 3206431, No. 3692525, No. 3794493, No. 3936305,
Special Publication No. 36-10466, No. 42-4786, No. 48-763
No. 50-025337 and the like. The anti-fading agent represented by these compounds is used in an amount of 0.10 to 1.0 parts by weight, based on 1 part by weight of the total amount of two or more couplers represented by the general formula [] of the present invention.
It is particularly preferable to add 0.25 to 0.75 parts by weight. Further, it is preferable to add a hydroquinone derivative together with the coupler used in the present invention for the purpose of preventing staining and color mixing. Specific examples of hydroquinone derivatives that can be used in the present invention are listed below. (Hq-1) 2,5-di-t-octylhydroquinone (Hq-2) 2-t-octyl-5-methylhydroquinone (Hq-3) 2,6-di-n-dodecylhydroquinone (Hq-4) 2-n-dodecylhydroquinone (Hq-5) 2,2'-methylenebis-5,5'-di-t-butylhydroquinone (Hq-6) 2,5-di-n-octyl-hydroquinone (Hq-7) 2-Dodecylcarbamoylmethylhydroquinone (Hq-8) 2-(β-n-dodecyloxycarbonyl)ethyl-hydroquinone (Hq-9) 2-(N・N-dibutylcarbamoyl)hydroquinone (Hq-10) 2-n- Dodecyl-5-chloro-hydroquinone (Hq-11) 2-octadecyl-5-methylhydroquinone (Hq-12) 2,5-di-(p-methoxyphenyl)hydroquinone (Hq-13) 2-t-octylhydroquinone (Hq-14) 2-[β-{3-(3-sulfobenzamide)benzamide}ethyl]hydroquinone (Hq-15) 2,5-dichloro-3,6-diphenylhydroquinone (Hq-16) 2,6 -Dimethyl-3-t-octylhydroquinone (Hq-17) 2,3-dimethyl-5-t-octylhydroquinone (Hq-18) 2-{β-(dodecanoyloxy)ethyl}carbamoylhydroquinone (Hq-19) 2-Dodecyloxycarbonylhydroquinone (Hq-20) 2-{β-(4-octanamidophenyl)ethyl}hydroquinone (Hq-21) 2-Methyl-5-dodecylhydroquinone These hydroquinone derivatives may be used alone or in combination can be used in combination, and the amount added is usually 0.01 to 10 per mole of the total amount of couplers.
Moles, especially 0.05 to 3 moles are preferred. The phenolic cyan coupler according to the present invention, the above-mentioned antifading agent, and the hydroquinone derivative are all hydrophobic, and are preferably mixed and dissolved together to be dispersed. These mixtures are dissolved in an organic solvent that is immiscible with high boiling point water with a boiling point of 170°C or higher, a mixed solvent of the high boiling point solvent and a low boiling point organic solvent, or a mixed solvent of the high boiling point organic solvent and a water-soluble organic solvent, and this solution is are finely dispersed into oil droplets in an aqueous solution of hydrophilic colloid such as an aqueous gelatin solution by ultrasonic or mechanical methods. In this case, in order to improve dispersibility and stability of the dispersion, it is preferable to add an emulsifier (for example, a surfactant such as sodium dodecylbenzenesulfonate) to the hydrophilic colloid solution. In addition, if necessary, the low-boiling organic solvent or water-soluble organic solvent may be removed by heating the dispersion under reduced pressure or by cooling the dispersion to form a "nudel" and then washing with water. You can also do that. These emulsification and dispersion techniques are described in detail in specifications such as US Pat. No. 2,322,027 and US Pat. No. 2,806,170. An emulsified dispersion containing a coupler obtained by such a method may be added to a silver halide emulsion. A large number of high-boiling point water-immiscible organic solvents and low-boiling point or water-soluble organic solvents are conventionally known, and any of them may be appropriately selected and used. Examples of organic solvents that are immiscible with high boiling point water include the following. Di-n-butyl phthalate, benzyl phthalate, triphenyl phosphate, tri-o-cresyl phosphate, diphenyl mono-p-t-butylphenyl phosphate, monophenyl di-p-t-butyl phosphate, monophenyl di-p- t-Butylphenyl phosphate, diphenyl mono-o-chlorophenyl phosphate, mono-phenyl di-o
-chlorophenyl phosphate, tri-pt-
Butylphenyl phosphate, 5-t-butyl-
2-phenyl phenyl phosphate, dioctyl phthalate, sinonyl phthalate, dibutyl sebacate acetyl tributyl citrate, tri-t
-octylmeritate, n-nonylphenol,
Dioctylbutyl phosphate, N.N-diethyl laurylamide, 3-pentadecyl phenyl ethyl ether, 2,5-disec-amyl phenyl butyl ether, etc. Examples of the low boiling point organic solvent or water-soluble organic solvent include the following. (1) Substantially insoluble in water with low boiling points such as methyl, ethyl, propyl and butyl acetate, ethyl propionate, isopropyl acetate, secondary butyl alcohol, ethyl formate, nitromethane, nitroethane carbon tetrachloride, chloroform, etc. organic solvent. (2) Methyl isobutyl ketone, β-ethoxyethyl acetate, tetrahydrofurofuryl adipate, diethylene glycol monoacetate,
Water-soluble organic solvents such as methoxy triglycol acetate, methyl cellosolve acetate, acetonyl acetone, diacetone alcohol, butyl carbitol, butyl cellosolve, methyl carbitol, methyl acetone, methanol, ethanol, acetonitrile, dimethyl formamide, dioxane, etc. . Usually, a cyan coupler dispersion is added to a red-sensitive silver halide emulsion, and this is also the most typical embodiment in the present invention. As the silver halide, all silver halides such as silver chloride, silver bromide, silver iodide, silver chlorobromide, silver iodobromide, silver chloroiodobromide, and mixtures thereof can be used. Hydrophilic colloids include gelatin, phthalated gelatin, phenylcarbamylated gelatin,
Gelatin derivatives such as malonated gelatin are commonly used, but it is also possible to use conventionally known hydrophilic colloids as a partial or complete substitute. In producing the silver halide color photographic emulsion of the present invention, all the methods conventionally used in these productions can be applied. For example, (1) sensitization with noble metal sensitizers, sulfur sensitizers, selenium sensitizers, ring element sensitizers, etc., (2) addition of binders for silver halide,
(3) Spectral sensitization and superchromatic sensitization by adding cyanine, merocyanine, carbocyanine dyes, or a combination of these with styryl dyes, etc. (4) Addition of agents to prevent sensitivity reduction and fogging. ,(Five)
Hardening of the emulsion, (6) addition of surfactants to improve coating properties, emulsification, permeability, defoaming, antistatic properties, adhesion resistance, etc. can be carried out as appropriate. The silver halide color photographic emulsion of the present invention can be applied to the production of all kinds of coupler-containing internal color photographic light-sensitive materials such as color negative films, color positive films, color reversal films, and color papers. Example 1 The solubility of a cyan coupler in a high boiling point organic solvent was tested. Weigh the couplers alone or in combination so that the total amount is 0.10 mol, and add 60
The solubility was compared using the minimum amount of dibutyl phthalate (DBP) required for complete dissolution at ℃.
The results were as shown in Table 1.

【table】

[Table] As is clear from the results in Table 1, the solubility of samples 4 to 7 according to the present invention is superior to samples 1 to 3 in which couplers were used alone. In addition, as is clear from the results of samples 10 to 12, in the method of combining couplers other than the present invention,
There is even a tendency for the solubility to deteriorate rather than to improve. Example 2 In order to produce a stable emulsified dispersion, it is preferable that the supersaturated solution has excellent stability. Therefore, in order to find out the stability of supersaturated solutions, 20 ml of dibutyl phthalate and a sample were sealed in a glass tube with an inner diameter of 1.5 cm.
It was heated to 100°C to completely dissolve it. Next, after cooling rapidly by standing in ice water, it was placed in an electric refrigerator and allowed to stand at 5°C to observe the state of crystal precipitation. The results were as shown in Table 2.

【table】

[Table] According to the results in Table 2, when the coupler of the present invention is used in combination, the stability of the supersaturated solution is improved, and the anti-fading agent is added to about 50% of the coupler without increasing the amount of the high-boiling organic solvent. There was no problem. Example 3

【table】

[Table] 〓Soda
After completely dissolving liquids A and B having the above composition at 60°C, add liquid A to liquid B, stir for 5 minutes in a homomixer, and then use a homogenizer to reduce the average particle size of the oil droplet dispersed particles to approx. It was dispersed until it became 0.2μ. Next, this dispersion was mixed into a red-sensitive silver chlorobromide emulsion (silver chloride 55
mol%, silver bromide 45 mol% silver halide 5 mol,
(containing 1300 g of gelatin) to prepare a coating solution for a red-sensitive emulsion layer. These silver halide emulsions were passed through stainless steel piping with an inner diameter of 5 cm for 48 hours at a flow rate of 2 per minute using a circulation pump while maintaining the temperature at 40°C. Inner wall area
The precipitate adhering to an area of 100 cm ² was collected, and only hydrophobic substances were separated and weighed. coupler used
(a), anti-fading agent (b) and dibutyl phthalate amount x
ml and the experimental results are shown in Table 3.

【table】

[Table] As is clear from the results in Table 3, it can be seen that the silver halide emulsions according to the present invention have excellent long-term stagnation properties even when the amount of high-boiling organic solvent used is small. Next, when samples with the same contents as those in Table 3 were coated for a long time using a small coating machine, data on coating properties correlated with the results in Table 3, and the samples with less deposits attached had better results. was obtained, and those with a large amount of deposits had defects such as coating streaks and repelling. Example 4 The same samples used in Example 3 were coated on polyethylene coated paper so that the amount of silver was 3.5 mg/100 cm ² . Furthermore, a protective layer is provided on each of these upper layers so that the gelatin content is 15mg/ ^100cm2 .
A silver halide color photographic material was prepared. These samples were exposed to a light wedge according to the sensitometric method, and then subjected to color development processing in the processing steps shown below. Processing process (30℃) Processing time Color development 3 minutes 30 seconds Bleach fixing 1 minute 30 seconds Water washing 3 minutes 30 seconds Dry Color developer composition: Benzyl alcohol 5.0ml Sodium hexametaphosphate 2.5g Anhydrous sodium sulfite 1.9g Sodium bromide 1.4g Potassium bromide 0.5g Borax 39.1g N-ethyl-N-β-methanesulfonamidoethyl-4-aminoaniline sulfate 5.0g Add water to make 1, and use sodium hydroxide to
Adjust to PH7.2. Bleach-fix solution composition: Iron ammonium ethylenediaminetetraacetate 61.0g Diammonium ethylenediaminetetraacetate 5.0g Ammonium thiosulfate 124.5g Sodium metabisulfite 13.3g Anhydrous sodium sulfite 2.7g Add water to make 1, use aqueous ammonia to adjust the pH.
Adjust to 7.20. The surface conditions of these treated samples were investigated.
The results were as shown in Table 4.

【table】

[Table] As is clear from the results in Table 4-1, the samples according to the present invention are good, but the samples other than the present invention have matte surfaces due to precipitation, or high boiling point When the amount of solvent was increased, the gloss deteriorated. Next, the results of measuring the sharpness of Samples 4, 9, 11, and 13 are shown in Table 4-2. The sharpness (U ₀ .5) is
This is the spatial frequency value at which the MTF decreases by 50%.

[Table] As is clear from Table 4-2, the images according to the present invention have excellent sharpness. Next, the image fastness of Samples 4, 9, 11, and 13 was examined in the same manner. It was stored in a dark place at 70°C and 80RH% for 21 days, and the concentration after storage of the part with an initial red density of 1.0 was measured. The results were as shown in Table 4-3.

[Table] As is clear from Table 4-3, the compound (9) in which the coupler according to the present invention is used can significantly reduce the amount of high-boiling organic solvent that degrades image fastness. Image robustness is improved compared to sample (4) using a coupler alone. Furthermore, since it is possible to add an anti-fading agent, the present invention can provide color photographic materials with excellent image fastness, such as Samples (11) and (13).

Claims (1)

[Scope of Claims] 1. A silver halide color photographic emulsion comprising at least two hydrophobic phenolic cyan dye-forming couplers represented by the following general formula dispersed in oil droplets. general formula [In the formula, R ₁ represents a hydrogen atom, a methyl group or an ethyl group, n represents an integer of 0 to 2, and R ₂ and R ₃ represent a hydrogen atom, an alkyl group or an alkoxy group. However, the sum of the number of carbon atoms of R ₂ and R ₃ is 8 to 15. ]