DE3785231T2 - METHOD FOR PRODUCING COLOR IMAGES. - Google Patents

Description

The present invention relates to a process for producing color images on silver halide color photographic materials and in particular to the use of improved color couplers without the use of benzyl alcohol to reduce processing time.

A silver halide color photographic material has a multilayer light-sensitive film coated on a support containing three kinds of silver halide emulsion layers which are selectively sensitized so that the layers can have photosensitivities to blue light, green light and red light, respectively. For example, a so-called color photographic paper (hereinafter referred to as "color paper") generally has a red-sensitive emulsion layer, a green-sensitive emulsion layer and a blue-sensitive emulsion layer coated on a support to be exposed, and in addition, for example, color stain preventive or ultraviolet absorbing intermediate layers and protective layers are provided between the light-sensitive layers.

To produce color photographic images, photographic couplers for the three colors yellow, magenta and cyan are added to the light-sensitive layers and the photographic materials are color-developed with a so-called color developer after they have been exposed. The coupling reaction between the oxidized product of an aromatic primary amine and the coupler causes the formation of colored dyes. As high a coupling rate of the reaction as possible and couplers with a higher coloring power so that a higher color density is obtained within the limited development time are desired. In addition, it is necessary that the colored dyes each are sharp cyan, magenta and yellow dyes with low side absorption and that they form colour photographic images with good colour reproducibility.

On the other hand, it is required that the color photographic images formed have good preservation stability under different conditions. In order to meet this requirement, it is important that the decolorization or color change rate of the colored dyes having different color tones is slow, and that the decolorization rate is as uniform as possible over the entire range of color image density, with the change in the color balance of the remaining color image being small.

To solve these problems, so-called oil-soluble couplers have been proposed, which are dissolved in a high-boiling or low-boiling organic solvent, and the resulting coupler solution is emulsified, dispersed and added to an emulsion layer. However, the use of such couplers is accompanied by difficult problems such as the color developer hardly penetrates into the oil droplet containing the coupler dispersion, the agent has poor oleophilic properties and a low color density. Under these circumstances, various types of developer penetrants have been studied. In particular, the addition of benzyl alcohol to color developers to accelerate color development has been widely used for processing color photographic materials, especially color papers, since the color-accelerating effect by the addition of benzyl alcohol is considerable.

However, the use of benzyl alcohol requires diethylene glycol, triethylene glycol or alkanolamines as solvents because benzyl alcohol has poor water solubility. Benzyl alcohol and these solvents have high BOD and COD values, which are environmental pollution load values, and therefore the elimination of benzyl alcohol is the need to reduce environmental pollution.

In addition, even if such solvents are used, the dissolution of benzyl alcohol in the solvents requires much time, and therefore the use of benzyl alcohol is not preferred since it is desirable to reduce the time required for the preparation of photographic processing solutions.

Furthermore, in the case where benzyl alcohol is carried into the bleaching bath or bleach-fixing bath, which is the bath following the developing bath, it causes the formation of a leuco dye of a cyan dye, thereby causing a decrease in color density. In addition, the use of benzyl alcohol retards the rate at which the developing components are washed out, which often adversely affects the image retention stability of the photographic materials after processing. Therefore, taking into account the reasons mentioned above, benzyl alcohol is preferably not used.

By conventional means, color development is generally completed within 3 to 4 minutes, and recently, with the reduction of the delivery time of commercial color images and the reduction of the workload of development laboratories, shortening the processing time has become necessary.

Despite this situation, the elimination of benzyl alcohol, which is a coloring accelerator, and the reduction of the development time without causing an inevitable noticeable deterioration of the color density was not possible.

To solve these problems, attempts have been made to use various types of color development accelerators (e.g. compounds described in US Patents 2,950,970, 2,515,147, 2,496,903, 2,304,925, 4,038,075 and 4,119,462, British Patents 1,430,998 and 1,455,413, Japanese Patent Application (OPI) Nos. 15831/78, 62450/80, 62451/80, 62452/80 and 62453/80 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application") and Japanese Patent Specifications Nos. 12422/76 and 49728/80) have been attempted to be used together with color developers, but sufficient color density has not yet been obtained.

The addition of 3-pyrazolidones to photographic materials (e.g. as described in Japanese Patent Application (OPI) Nos. 26338/85, 158444/85 and 158446/85) still has the defect that the sensitivity of the photographic materials is reduced and fog occurs during the formation of the photographic materials.

The addition of color developers to photographic materials (as described, for example, in U.S. Patents 3,719,492, 3,342,559 and 3,342,597 and Japanese Patent Application (OPI) Nos. 6235/81, 16133/81, 97531/82 and 83565/82) also has the defect that the speed of color development is reduced and fog occurs, which is undesirable.

To overcome these problems, the use of silver chloride emulsions (as described, for example, in Janan patent applications (OPI) 95345/83, 232342/84 and 19140/85) was proposed.

Furthermore, in the conventional method for forming color images in which a reflective silver halide photographic material is processed using a color developer containing little or no benzyl alcohol, the high boiling organic solvents used as coupler solvents are as follows: dibutyl phthalate (as disclosed in Japanese Patent Application (OPI) Nos. 200037/82, 50536/83, 48755/84, 177553/84 and 162256/85 and Japanese Patent Publication No. 29461/74), dioctyl phthalate (as described, for example, in Japanese Patent Application (OPI) Nos. 26338/85, 26339/85, 158446/85 and 172042/85), tricresyl phosphate (as described, for example, in Japanese Patent Application (OPI) Nos. 200037/82 and 50536/83 and Japanese Patent Publication No. 29461/74), dioctyl butyl phosphate (as described, for example, in Japanese Patent Application (OPI) No. 50536/83) and trioctyl phosphate (as described, for example, in Japanese Patent Applications 174836/84, 177553/84 and 162256/85).

However, no method has yet been found for forming more satisfactory color images in a shorter period of time using color developers containing substantially no benzyl alcohol.

Therefore, it is the object of the present invention to provide a method for forming color images in a short period of time by processing color photographic materials containing at least one oil-soluble coupler for color developers which contains substantially no benzyl alcohol, and the color images formed by this method should have good color reproducibility and high color image retention stability.

The object of the present invention can be achieved by providing a novel process for forming color images, wherein a silver halide color photographic material comprising at least one silver halide emulsion layer on a reflective support, which comprises an oleophilic fine grain dispersion containing a coupler capable of forming a color upon coupling with the oxidation product of an aromatic primary amine developing agent, and at least one high boiling organic solvent selected from the group consisting of the following formulas (I), (II), (III), (IV) and (V):

wherein W₁, W₂ and W₃ each represent a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, aryl or heterocyclic group: W₄ is W₁, O-W₁ or S-W₁: n is an integer of 1 to 5, and when n is 2 or more, W₄ may be the same or different: and in formula (V), W₁ and W₂ may be bonded to each other to form a condensed ring; imagewise exposed and then developed with a color developer containing an aromatic primary amine developing agent but substantially no benzyl alcohol, characterized in that the oleophilic fine grains have an average grain size of 0.25 µm or less, the organic solvents have a dielectric constant of 4.0 or more (25°C, 10 KHz) and the imagewise exposed photographic material is developed for 2 min 30 s or less.

In the present invention, the term "color developer substantially containing no benzyl alcohol" means that the concentration of benzyl alcohol in the color developer is 0.5 ml/L or less, and in particular, it is preferred that no benzyl alcohol is contained in the color developer.

The average grain size is measured using the photometric method of dynamic light scattering.

Preferred substances represented by the above formulas (I), (II), (III), (IV) and (V) are those in which the total of carbon atoms in W₁ and W₂ or W₁, W₂ and W₃ (or W₄) is about 8 or more, and whose dielectric constant is 4.00 or more (25°C, 10 KHz).

The dielectric constant can be readily obtained by measuring it by the transformer bridge method. When W₁, W₂ and W₃ have substituents, the substituents may contain one or more linking groups selected from -COO-, CON, -R⁸-N and -O-, wherein R⁸ represents a divalent to hexavalent group derived from a phenyl group by removing hydrogen atom(s) therefrom.

In formulas (I), (II), (III), (IV) and (V), the alkyl group represented by W₁, W₂, W₃ or W₄ may be either linear or branched, and includes, for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group or an eicosyl group.

The substituents for these alkyl groups are, for example, in the case of the aforementioned formula (I), halogen atoms, cycloalkyl groups, aryl groups and ester groups, examples of the substituted alkyl groups include:

halogen-substituted groups (such as F-, Cl- or Br-substituted groups) such as -C₂HF₄, -C₅H₃F₈, -C₄H₃F₁₆, -C₂H₄Cl, -C₃H₆Cl, -C₃H₅Cl₂, -C₃H₅ClBr, or -C₃H₅Br₂;

Cycloalkyl substituted groups such as

Aryl substituted groups such as

Dibasic, ester-forming acid groups such as

Lactate forming groups such as

Citrate forming groups such as

Malate forming groups such as

-CH2CH(OH)-COOC6H13;

Tartrate forming groups such as

-CH(OH)CH(OH)COOC�8;H₁₇, or

and the group

In formulas (II) to (V), the alkyl group may be substituted with the same substituents as those for the alkyl group of the formula (I) as mentioned above.

In addition, in the formula (V), W₁ and W₂ may be bonded to each other to form a condensed ring such as an oxirane ring, an oxolane ring or an oxane ring.

The cycloalkyl group represented by W₁, W₂, W₃ or W₄ is, for example,

and the substituted cyclohexyl group represented by W₁, W₂, W₃ or W₄ is, for example,

The aryl group represented by W₁, W₂, W₃ or W₄ includes, for example, aromatic, substituted or unsubstituted, fused or non-fused, six-membered rings such as

and the substituted aryl group represented by the same, for example

Alkenyl groups include, for example, -C₄H₇, -C₅H₆, -C₆H₁₁, -C₇H₁₃, -C₈H₁₅, -C₅₀H₁₃, -C₅₀H₁₃, and -C₅₀H₃₅; and substituted alkenyl groups include, for example, those substituted with a halogen atom (e.g. F, Cl, Br) -OC₈H₁₇, -OC₅₁₂H₂₅,

are substituted,

or include e.g.

The unsubstituted or substituted heterocyclic groups represented by W₁, W₂, W₃ or W₄ include, for example,

Preferably, the high boiling organic solvents substituted with the substituents W₁, W₂, W₃ and/or W₄ have a dielectric constant of 5.00 or more at 25°C (10 KHz) and a viscosity of 20 mPa.s or more at 25°C. It is surprising that compounds satisfying these conditions can improve the coloring power of coloring dyes without deteriorating the absorbance or other characteristics of the dyes. Although the reason for these results is not clear, it is believed that the high boiling organic solvents having a high dielectric constant can absorb a large amount of colour developers, and that those having a viscosity of 20 mPa.s or more at 25ºC can reduce some of the adverse effects of the couplers and silver halides in the oil drops.

In the present invention, the amount of the high boiling organic solvent represented by formula (I), (II), (III), (IV) or (V) may be any desired amount depending on the kind and amount of the couplers used. The weight ratio of high boiling solvent/coupler is preferably in the range of 0.05 to 20. The high boiling organic solvents represented by formula (I), (II), (III), (IV) or (V) of the present invention may be used alone or as a mixture of two or more thereof.

Of the compounds of formulas (I) to (V), those of formulas (I) and (II) are preferred, with those of formula (I) being particularly preferred.

Specific examples of high boiling organic solvents are given below.

The oleophilic fine grains to be used in the present invention can generally be obtained by a method in which a solution of the compound dissolved in a substantially water-insoluble high-boiling organic solvent and a hydrophilic colloid solution are mixed and dispersed. This method is described, for example, in U.S. Patents 2,322,027, 2,533,514 and 2,801,171. If necessary, a low-boiling solvent or a water-miscible organic solvent can be used, and these solvents are removed by evaporation to dryness or washing with water. In the case of this method, a surfactant is preferably used.

In general, the reduction in the grain size of the above oleophilic fine grains can be achieved by the ingenuity of the apparatus or the operation including the selection of the types of surfactants, the increase in the amount of surfactant to be used, the increase in the viscosity of the hydrophilic colloid solution, the reduction in the viscosity of the organic layer in which the above compound has been dissolved by the use of a low boiling point solvent, the increase in the rotation of the stirring blades in the emulsifier to enhance the cutting force, and the increase in the emulsification time. Other methods for preparing the oleophilic fine grain dispersion can also be used. as described, for example, in US Patent 3,619,195, West German Patent (OAS) No. 1,957,467 and Japanese Patent Application (OPI) No. 59943/76. Preferred surfactants are described, for example, in Japanese Patent Publication No. 4923/84 and US Patent 3,676,141.

Particularly preferred surfactants are the following compounds which have an aliphatic group and a sulfonic acid group.

These can be used alone or in combination.

The grain size of the oleophilic fine grains of the present invention is 0.25 µm or less, preferably 0.05 µm to 0.20 µm.

The oleophilic fine grains may contain, in addition to the coupler, a discoloration inhibitor, an ultraviolet absorber, a DIR coupler and similar oleophilic photographic elements.

The "reflective support" to be used in the present invention is one having an improved reflectivity which is effective in improving the sharpness of the color image formed in the silver halide emulsion layer. Examples of such reflective supports include those formed by coating a hydrophobic resin containing a dispersion of a light-reflecting substance such as titanium oxide, zinc oxide, calcium carbonate or calcium sulfate on a support, or those made of a hydrophobic resin containing a dispersion of such a light-reflecting substance. For example, baryta paper, polyethylene-coated paper, synthetic polypropylene paper, and transparent supports on which a reflective layer has been provided or which contain a reflective substance such as a glass plate, polyterephthalate, cellulose triacetate, cellulose nitrate and similar polyester films and polyamide films, polycarbonate films and polystyrene films. These supports can be suitably selected according to the use and purpose of the photographic materials.

Next, the photographic processing step (image forming step) of the present invention will be described below.

The color development step of the present invention proceeds rapidly: The processing time is 2 min 30 s or less. The preferred processing time is 1 to 2 min. "Processing time" means the time from the first contact of the photographic material to be processed with the color developer to the contact of the material with the next bath, including the time for material transfer between baths.

The color developer to be used in the present invention is preferably an alkaline aqueous solution mainly containing an aromatic primary amine color developer. Paraphenylenediamine compounds are preferably used as the color developer, and typical examples thereof are 3-methyl- 4-amino-N,N-diethylaniline, 3-methyl-4-amino-N-ethyl-N-β-hydroxyethylaniline, 3-methyl-4-amino-N-ethyl-N-β-methanesulfonamidoethylaniline, 3-methyl-4-amino-N-ethyl-N-β-methoxyethylaniline, and sulfates, hydrochlorides, phosphates, p-toluenesulfonates, tetraphenylborates and p-(t-octyl)benzenesulfonates thereof.

Of these, 3-methyl-4-amino-N-ethyl-N-β-hydroxyethylaniline and 3-methyl-4-amino-N-ethyl-N-β-methanesulfonamidoethylaniline are preferred, and in particular 3-methyl-4-amino-N-ethyl-N-β-methanesulfonamidoethylaniline is preferred.

Aminophenyl derivatives include, for example, o-aminophenol, p-aminophenol, 4-amino-2-methylphenol, 2-amino-3-methylphenol, and 2-hydroxy-3-amino-1,4-dimethylbenzene.

In addition, compounds described in L.F.A. Mason, Photographic Processing Chemistry, pages 226 to 229 (Focal Press), U.S. Patents 2,193,015 and 2,592,364 and Japanese Patent Application (OPI) No. 64933/73 can also be used. If necessary, two or more color developers can be used together.

The processing temperature of the color developers according to the invention is preferably 30 to 50°C, more preferably 33 to 45°C.

As the development accelerator, any compound can be used as long as it substantially does not contain benzyl alcohol. For example, various kinds of pyridinium compounds and other cationic compounds, cationic dyes such as phenosafarnin, neutral salts such as thallium nitrate and potassium nitrate described in U.S. Patent 2,648,604, Japanese Patent Publication No. 9503/69 and U.S. Patent 3,171,247, nonionic compounds such as polyethylene glycol and derivatives thereof and polythioethers described in Japanese Patent Publication No. 9304/69, U.S. Patents 2,533,990, 2,531,832, 2,950,970 and 2,577,127, thioether compounds described in U.S. Patent 3,171,247 and Japanese Patent Publication No. 3,171,247. Patent 3,201,242 and compounds described in Japanese Patent Application (OPI) Nos. 156934/83 and 220344/85.

For the short-term development according to the invention, not only means for accelerating the development but also techniques for preventing the formation of fog are an important subject.

A fog inhibitor can be used for the color developer of the present invention. Alkali metal halides such as potassium bromide, sodium bromide and potassium iodide and organic fog inhibitors are preferably used as the fog inhibitors of the present invention. Examples of useful organic fog inhibitors are nitrogen-containing heterocyclic compounds such as benzotriazole, 6-nitrobenzimidazole, 5-nitrosoindazole, 5-methylbenzotriazole, 5-nitrobenzotriazole, 5-chlorobenzotriazole, 2-thiazolylbenzimidazole, 2-thiazolylmethylbenzimidazole, hydroxyazaindolizine, mercapto-substituted heterocyclic compounds such as 1-phenyl-5-mercaptotetrazole, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole and also mercapto-substituted aromatic compounds such as thiosalicylic acid. In particular, the halides are particularly preferred. The fog inhibitor can be dissolved out of the photographic material during processing so that it settles in the color developer solution.

The color developer according to the invention can also contain pH buffers such as alkali metal carbonates, borates or phosphates, preservatives such as hydroxylamines, triethanolamines, compounds described in DE-A-2,622,950, sulfites or bisulfites, organic solvents such as diethylene glycol, dye-forming couplers, competing couplers, nucleating agents such as sodium borohydride, auxiliary developers such as 1-phenyl-3-pyrazolidone, adhesives and chelating agents such as aminopolycarboxylic acids, e.g. ethylenediaminetetraacetic acid, nitrilotriacetic acid, cyclohexanediaminetetraacetic acid, iminodiacetic acid, N-hydroxymethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminohexaacetic acid and compounds described in Japanese Patent Application (OPI) No. 195845/83. 1-Hydroxyethylidene-1,1'-diphosphonic acid, organic phosphonic acids described in Research Disclosure, RD No. 18170 (May 1979), aminophosphonic acids, e.g. aminotris(methylenephosphonic acid) and ethylenediamine-N,N,N',N'-tetramethylenephosphonic acid and phosphonocarboxylic acids described in the Japanese Patent Application (OPI) Nos. 102726/77, 42730/78, 121127/79, 4024/80, 4025/80, 126241/80, 65955/80 and 65956/80 and Research Disclosure RD No. 18170 (May 1979).

If necessary, the color development series may comprise two or more color development baths, and a color development replenisher may be replenished into the first pre-bath or the last post-bath, whereby the development time can be reduced and the amount of replenisher can be reduced.

The silver halide color photographic materials are generally bleached after they have been color developed. Bleaching can be carried out simultaneously with fixation (bleach-fixation) or alternatively separately. Bleaching agents that can be used include, for example, compounds of polyvalent metals such as iron(III), cobalt(III), chromium(VI) or copper(II), peracids, quinones and nitroso compounds. For example, ferricyanides, dichromates, organic complexes with iron(III) or cobalt(III) such as complexes of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, nitrilotriacetic acid, 1,3-diamino-2-propanoltetraacetic acid or similar aminopolycarboxylic acids or with citric acid, tartaric acid, hydroxysuccinic acid or similar organic acids, persulfates, manganates and nitrosophenol. In particular, potassium ferricyanide, sodium ethylenediaminetetraacetate/iron(III), ammonium ethylenediaminetetraacetate/iron(III), ammonium triethylenetetraaminepentaacetate/iron(III) and persulfates are particularly preferred. Ethylenediaminetetraacetate/iron(III) complexes can be used both in an independent bleaching solution and in a combined bleach-fixing solution.

The bleaching solution and the bleach-fixing solution may contain different types of accelerators if necessary. For example, a bromide ion, an iodide ion, and thiourea compounds described in US Patent 3,706,561, Japanese Patent Publication Nos. 8506/70 and 26586/74, Japanese Patent Application (OPI) Nos. 32735/78, 36233/78 and 37016/78, thiol compounds described in Japanese Patent Application (OPI) Nos. 124424/78, 95631/78, 57831/78, 32736/78, 65732/78 and 52534/79 and US Patent 3,893,858, heterocyclic compounds described in Japanese Patent Application (OPI) Nos. 59644/74, 140129/75, 28426/78, 141623/78, 104232/78 and 35727/79, thioether compounds described in Japanese Patent Application (OPI) Nos. 20832/77, 25064/80 and 26506/89, quaternary amines described in Japanese Patent Application (OPI) No. 84440/73 and tricarbamoyl compounds described in Japanese Patent Application (OPI) No. 42349/74.

As the fixing agents, thiosulfates, thiocyanates, thioether compounds, thioureas and a large number of iodides can be mentioned. In particular, thiosulfates are generally used. As preservatives for the bleach-fixing solution or the fixing solution, sulfites or bisulfites or carbonyldisulfuric acid adducts are preferred.

After bleach-fixing or fixing, the photographic materials are generally washed. In the washing step, various kinds of known compounds can be used for preventing precipitation or for water economy. For example, softeners for hard water such as inorganic phosphoric acids, aminopolycarboxylic acids or organic phosphoric acids, bactericides or fungicides for preventing the growth of various bacteria, algae or fungi, hardeners such as magnesium salts or aluminum salts and surfactants for preventing drying load or unevenness can be added if needed. If necessary, compounds described in LE West, Photographic Science and Engineering, Vol. 9, No. 6 (1965). In particular, the addition of the chelating agent or fungicide is effective. For the washing step, a multi-stage countercurrent flow system (eg, with two stages to five stages) can be used for water economy reasons.

After the washing step or instead of the washing step, the photographic material may be subjected to a multi-stage countercurrent stabilization system as described in Japanese Patent Application (OPI) No. 8543/82. This step requires a countercurrent system bath series comprising two to nine baths. Various types of compounds are added to the stabilization baths to stabilize images. For example, pH-regulating buffers (such as borates, metaborates, borax, phosphates, carbonates, potassium hydroxide, sodium hydroxide, ammonia, monocarboxylic acids, dicarboxylic acids and polycarboxylic acids) and formalin may be added. In addition, hard water softeners (such as inorganic phosphoric acids, aminopolycarboxylic acids, organic phosphoric acids, aminopolyphosphonic acids and phosphonocarboxylic acids), bactericides (such as proxel, isothiazolone, 4-thiazolylbenzimidazole and halogenated phenolbenzotriazoles), surfactants, optical brighteners and hardeners may be additionally added if required.

Various types of ammonium salts such as ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium phosphate, ammonium sulfite or ammonium thiosulfate can be added as film pH regulators to regulate the pH value of the film after processing.

The colour coupler added to the photographic materials preferably has a ballast group or is polymerised to be diffusion-resistant. 2-equivalent colour couplers in which the coupling-active sites are substituted with groups that can be split off are more suitable than 4- Equivalent color couplers having hydrogen atoms in the coupling active sites are preferred because the amount of silver to be coated can be reduced. Furthermore, couplers for forming colored dyes with appropriate diffusivity, non-coloring couplers, DIR couplers for releasing a development inhibitor during the coupling reaction, and couplers for releasing a development accelerator during the coupling reaction can also be used.

Typical examples of yellow couplers that can be used in the present invention are oil-protected acylacetamide couplers. Specific examples thereof are described in U.S. Patents 2,407,210, 2,875,057 and 3,265,506. In the present invention, 2-equivalent yellow couplers are preferably used, and typical examples thereof are the oxygen-releasing yellow couplers described in U.S. Patents 3,408,194 3,447,928, 3,933,501 and 4,022,620 and nitrogen-releasing yellow couplers described in Japanese Patent Publication No. 10739/83, U.S. Patents 3,408,194 3,447,928, 3,933,501 and 4,022,620. Patents 4,401,752 and 4,326,024, Research Disclosure, RD No. 18053 (April 1979), British Patent 1,425,020 and DE-A-2,219,917, 2,261,361, 2,329,587 and 2,433,812. α-pivaloylacetanilide couplers are excellent in terms of fastness particularly light fastness of colored dyes. On the other hand, α-benzoylacetanilide couplers are excellent in terms of producing high color density.

Magenta couplers which can be used in the present invention include oil-protected indazolone or cyanoacetyl couplers, preferably 5-pyrazolone couplers and pyrazoloazole couplers such as pyrazolotriazoles. Of the 5-pyrazolone couplers, those whose 3-position is substituted with an arylamino group or an acylamino group are preferred in view of the hue and color density of the colored dyes. Typical examples of these couplers are described in US Patents 2,311,082, 2,343,703, 2,600,788, 2,908,573, 3,062,653, 3,152,896 and 3,936,015. In view of the Groups of 2-equivalent 5-pyrazolone couplers which can be split off are nitrogen leaving groups described in US Patent 4,310,619 and arylthio groups described in US Patent 4,351,897, particularly preferred. In addition, ballast group-containing 5-pyrazolone couplers described in European Patent 73,636 are preferred for forming color images of high color density.

Pyrazoloazole couplers that can be used in the present invention include pyrazolobenzimidazoles described in U.S. Patent 3,369,879, preferably pyrazolo[5,1/c][1,2,4]triazoles described in U.S. Patent 3,725,067, pyrazolotetrazoles described in Research Disclosure, RD No. 24220 (June 1984), and pyrazolopyrazoles described in Research Disclosure, RD No. 24230 (June 1984). In particular, imidazo[1,2-b]pyrazoles, which are described in European Patent 119,741, are preferred because the yellow side absorption of the dyes formed is small and their light resistance is high, and in particular, pyrazolo[1,5-b][1,2,4]triazoles, which are described in European Patent 119,860, are particularly preferred.

Cyan couplers that can be used in the present invention are oil-protected naphthol and phenol couplers, typical examples of which are naphthol couplers described in U.S. Patent 2,474,293, preferably oxygen-leaving group 2-equivalent naphthol couplers described in U.S. Patents 4,052,212, 4,146,396, 4,228,233 and 4,296,200. Specific examples of phenol couplers are described in U.S. Patents 2,369,929, 2,801,171, 2,772,162 and 2,895,826.

Cyan couplers which are resistant to humidity and temperature are preferred in the present invention, and typical examples thereof are phenol cyan couplers whose phenol nucleus contains an ethyl or a higher alkyl group at the m-position described in U.S. Patent 3,772,002, 2,5-diacylamino-substituted phenol couplers described in U.S. Patents 2,772,162, 3,758,308, 4,126,396, 4,334,011 and 4,327,173, DE-A-3,329,729 and Japanese Patent Application (OPI) No. 166956/84, and phenol couplers having a 2-ureido group and a 5-acylamino group described in U.S. Patents 3,446,622, 4,333,999, 4,451,559 and 4,427,767.

The graininess can be improved by adding a coupler capable of forming a colored dye with suitable diffusivity. Such dye-diffusing couplers are magenta couplers described in U.S. Patent 4,366,237 and British Patent 2,125,570, and yellow, magenta or cyan couplers described in European Patent 96,570 and DE-A-3,234,533.

The dye-forming couplers and the above-mentioned special couplers may be in the form of a dimer or higher polymer. Typical examples of polymerized dye-forming couplers are described in U.S. Patents 3,451,820 and 4,080,211. Specific examples of polymerized magenta couplers are described in British Patent 2,102,173 and U.S. Patent 4,367,282.

Regarding the addition of the couplers to the photographic materials of the present invention, two or more kinds of the couplers may be added to the same layer of the light-sensitive layer, or the same compound may be added to two or more different layers so that the photographic material has the required properties.

The standard amount of color coupler to be used is within 0.001 to 1 mol per mol of light-sensitive silver halide, and preferably the amount of yellow coupler is 0.01 to 0.5 mol, that of magenta coupler 0.003 to 0.3 mol and that of cyan coupler 0.002 to 0.3 mol each per mole of silver halide.

The photographic light-sensitive material used in the present invention may contain, for example, hydroquinone derivatives, aminophenol derivatives, amines, gallic acid derivatives, catechol derivatives, ascorbic acid derivatives, non-coloring couplers and sulfonamidophenol derivatives as color fog inhibitors or anti-color discoloration agents.

The photographic light-sensitive materials used in the present invention may contain a known discoloration inhibitor. Typical examples of organic discoloration inhibitors that can be used are hindered phenols such as hydroquinones, 6-hydroxychromans, 5-hydroxycoumarans, spirochromans, p-alkoxyphenols and diphenols and gallic acid derivatives, methylenedioxybenzenes, aminophenols, hindered amines and their ether and ester derivatives whose phenolic hydroxyl group is silylated or alkylated. In addition, metal complexes such as (bissalicylaldoximato)nickel complexes and (bis-N,N-dialkyldithiocarbamato)nickel complexes can also be used.

Compounds having partial structures of both a hindered amine and a hindered phenol in one molecule, described in U.S. Patent 4,268,593, are effective for preventing deterioration of yellow-colored images under heat, humidity and light. Spiroindanes, described in Japanese Patent Application (OPI) No. 159644/81, and hydroquinone diether- or hydroquinone monoether-substituted chromans are effective for preventing deterioration of magenta-colored images particularly under light.

Benzotriazole type ultraviolet absorbers are preferably used to improve durability, particularly the lightfastness of the cyan images. The ultraviolet absorber can be co-emulsified with the cyan coupler.

The amount of ultraviolet absorber to be coated is sufficient to impart sufficient light resistance to the cyan images. However, if the amount is too large, the unexposed part (white background part) of the color photographic material becomes yellowish and therefore, in general, the amount must preferably fall within the range of 1 x 10-4 mol/m² to 2 x 10-3 mol/m², particularly 5 x 10-4 mol/m² to 1.5 x 10-3 mol/m².

In forming the light-sensitive layer of ordinary color papers, the ultraviolet absorber is added to either, preferably both, of the layers adjacent to the two sides of the cyan coupler-containing red-sensitive emulsion layer. When the ultraviolet absorber is added to the intermediate layer between the green-sensitive layer and the red-sensitive layer, it may be co-emulsified with a color stain preventing agent. When the ultraviolet absorber is added to the protective layer, another protective layer may be provided as the outermost layer. The protective layer may, for example, contain a matting agent having any grain size.

The photographic light-sensitive materials used in the present invention may contain the ultraviolet absorber in the hydrophilic colloid layer.

The photographic light-sensitive materials used in the present invention may contain a water-soluble dye in the hydrophilic colloid layer as a filter dye or for preventing scattering or halation or for other various purposes.

The photographic light-sensitive materials used in the present invention may contain brighteners such as stilbene type, triazine type, oxazole type and coumaran type compounds in the photographic emulsion layers or in other hydrophilic colloid layers. The brighteners to be used may be water-soluble or, as required, water-insoluble brighteners may be used in the form of a dispersion.

As mentioned above, the present invention can be used for multilayer and multicolor photographic materials having at least two layers of different spectral sensitivities on a support. Multilayer natural color photographic materials generally have at least one red-sensitive emulsion layer, at least one green-sensitive emulsion layer and at least one blue-sensitive emulsion layer on a support. The order of these layers to be provided on the support can be freely selected as required. Each of the emulsion layers may contain two or more layers having different degrees of sensitivity, or a photosensitive layer may be provided between two or more layers having the same color sensitivity.

The photographic light-sensitive materials used in the present invention preferably have, in addition to the silver halide emulsion layers, auxiliary layers such as a protective layer, intermediate layer, filter layer, antihalation layer and reinforcing layer, if necessary. Gelatin is advantageously used as a binder or protective colloid to be added to the emulsion layer or intermediate layer of the photographic light-sensitive materials of the present invention, and other hydrophilic colloids can of course be used.

For example, proteins such as gelatin derivatives, graft polymers of gelatin and other high molecular weight substances, proteins such as albumin and casein, cellulose derivatives such as hydroxyethylcellulose, carboxymethylcellulose and cellulose sulfates, saccharide derivatives such as sodium alginate and starch derivatives, mono-cocopolymers of various synthetic hydrophilic high molecular weight substances such as polyvinyl alcohol, partially acetalized polyvinyl alcohol, poly-N-vinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinylimidazole and polyvinylpyrazole can be used.

Gelatins that can be used in the present invention include lime-treated gelatin, acid-treated gelatin and enzyme-treated gelatin described in Bull. Soc. Sci. Phot. Japan, No. 16, page 30 (1966), and in addition, hydrolyzed or enzyme-decomposed products of gelatins can also be used.

The photographic light-sensitive materials used in the present invention may further contain, in addition to the above-mentioned additives, various kinds of stabilizers, discoloration inhibitors, developers or their precursors, lubricants, mordants, matting agents, antistatic agents, plasticizers and other various kinds of additives useful for photographic light-sensitive materials. Typical examples of these additives are described in Research Disclosure, RD Nos. 17643 (December 1978) and 18716 (November 1979).

The silver halide emulsions that can be used in the present invention are those of silver bromide, silver chlorobromide and silver chloride which are substantially free of any silver iodide, and preferred silver halides are silver chlorobromide containing 20-98 mol% silver bromide.

In particular, for even faster processing, silver chlorobromide containing more than 80 mol% silver chloride is preferably used. Furthermore, the present grains may have a combination of these structures.

The silver halide grains to be used in the present invention may contain different internal and surface layer phases, or they may have a multiphase constitution with an epitaxial structure, or on the other hand, they may have a completely uniform phase.

The average grain size of the silver halide grains to be used in the present invention is preferably 0.1 µm to 2 µm, particularly preferably 0.15 µm to 1 µm. (The grain size is the grain diameter in the case of spherical or nearly spherical grains, or it is the side length in the case of cubic grains, and the average grain size is represented on the basis of the average value of the projected area of the grains.) The grain size distribution may be either narrow or broad. In particular, a so-called monodispersed silver halide emulsion is preferably used for the present invention, in which the value of the standard deviation in the grain size distribution curve of the silver halide emulsion divided by the average grain size thereof (or that is, the coefficient of variation) may be within 20% or less, particularly preferably 15% or less. In order to satisfy the desired gradation of the photographic light-sensitive materials, two or more monodispersed silver halide emulsions (the monodispersed system preferably having the previously defined coefficient of variation) having substantially the same color sensitivity but having different grain size distributions may be added to the same layer or several different layers which are laminated. In addition, two or more kinds of polydispersed silver halide emulsions or a combination of a monodispersed emulsion and a polydispersed Emulsion can be used in a mixture or in a laminate.

The shape of the silver halide grains to be used in the present invention may be a cubic, octahedral, dodecahedral, tetradecahedral or similar regular crystal or may be a spherical or similar irregular crystal, or otherwise the present grains may contain composite forms of these crystal shapes. Cubic, tetradecahedral or similar regular crystal grains are preferably used. In addition, the present grains may be tabular, and in particular, an emulsion in which 50% or more of the total projected area of the grains contains tabular grains having an aspect ratio (length/thickness) of 5 or more, particularly 8 or more, can be used for the present invention. An emulsion containing a mixture of these various types of crystal shapes can of course be used. These various types of emulsions may be of either a surface latent image type in which a latent image is formed substantially on the surface of the grains or an internal latent image type in which a latent image is formed substantially in the internal part of the grains. In the present invention, surface latent image silver halide emulsions are preferably used.

The photographic emulsions to be used in the present invention can be prepared by a variety of methods, for example as described in P. Glafkides, Chemie et Physique Photographique Paul Montel Co., 1967), GF Duffin, Photographic Emulsion Chemistry (Focal Press Co., 1966) and VL Zelikman et al. Making and Coating Photographic Emulsion (Focal Press Co., 1964). For example, the present emulsions can be obtained by any of an acidic method, a neutral method or an ammonia method, and for the reaction of a soluble silver salt and a soluble halide, a single-jet method, a double-jet method or a double-jet method can be used. or a combination thereof. A so-called reverse mixing process in which the grains are formed in the presence of an excess of silver ions can also be used. In addition, a so-called controlled two-jet process, which is a type of the two-jet process, in which the pAg value in the liquid phase is kept constant to form the silver halide grains, can also be used. According to this process, silver halide emulsions with a regular crystalline shape and almost uniform grain size can be obtained.

In addition, emulsions prepared by a conversion process which includes a step for converting the silver halide grains already formed to those having a lower solubility product during the process until the formation of the silver halide grains is completed, or emulsions prepared by a process in which the same halogen conversion is applied to the grains already formed after the formation of these grains is completed, can be used.

For example, a cadmium salt, a zinc salt, a lead salt, a thallium salt, an iridium salt or a complex thereof, a rhodium salt or a complex thereof, and an iron salt or a complex thereof may be present in the step of forming the silver halide grains or physically ripening them for preventing the reciprocity law defect, e.g., increasing the sensitivity and controlling the gradation.

The silver halide grains are generally physically ripened, demineralized or chemically ripened after their formation and then coated on a support.

Known silver halide solvents (e.g. ammonia, phodan potassium or thioethers and thione compounds described in US Patent 3,271,157 and Japanese Patent Application (CPI) Nos. 12360/76, 82408/78, 144319/78, 100717/79 and 155828/78 described) can be used for precipitation, physical ripening and chemical ripening. The removal of soluble silver salts from the physically ripened solutions can be carried out by noodle washing, flocculation precipitation or ultrafiltration.

The silver halide emulsions to be used in the present invention can be sensitized by a sulfur sensitization method using sulfur-containing compounds that can react with an active gelatin or silver (e.g. thiosulfates, thioureas, mercapto compounds and rhodanines), a reductive sensitization method using reducing agents (e.g. tin(II) salts, amines, hydrazine derivatives, formamidine sulfine, silane compounds), or a noble metal sensitization method using metal compounds (e.g. gold complexes and complexes of metals of Group 8 of the Periodic Table such as Pt, Ir, Pd, Rh, Fe), and these sensitization methods can be used alone or in the form of a combination thereof.

Of these chemical sensitization methods, sulfur sensitization alone is preferred.

Each of the blue-sensitive, green-sensitive and red-sensitive emulsions of the present invention are spectrally sensitized with methine dyes of the similar other dyes so that they have the respective color sensitivity. Useful dyes include cyanine dyes, merocyanine dyes, cyanine complex dyes, merocyanine complex dyes, holopolar cyanine dyes, hemicyanine dyes, styryl dyes and hemioxonol dyes. Particularly useful dyes are those belonging to cyanine dyes, merocyanine dyes and merocyanine complex dyes. Any basic heterocyclic nucleus which may generally be contained in cyanine dyes, can be used for these dyes. For example, these nuclei include pyrroline, oxazoline, thiazoline, pyrrole, oxazole, thiazole, selenazole, imidazole, tetrazole and pyridine nuclei, heterocyclic nuclei fused with alicyclic hydrocarbon ring and heterocyclic nuclei fused with aromatic hydrocarbon ring such as indolenine, benzindolenine, indole, benzoxazole, naphthoxazole, benzothiazole, naphthothiazole, benzoselenazole, benzimidazole and quinoline nuclei. These nuclei may be substituted at their carbon atoms.

Merocyanine dyes and merocyanine complex dyes may contain a 5- or 6-membered heterocyclic nucleus containing a ketomethylene structure, such as a pyrazolin-5-one, thiohydantoin, 2-thiooxazolidine-2,4-dione, thiazolidine-2,4-dione, rhodanine or thiobarbituric acid nucleus.

These sensitizing dyes can be used alone or in the form of a mixture thereof, with the combination of sensitizing dyes often being used for the purpose of supersensitization. Typical examples of this are described in the U.S. Patents 2,688,545 2,977,229, 3,397,060, 3,522,052, 3,527,641, 3,617,293, 3,628,964, 3,666,480, 3,672,898, 3,679,428, 3,703,377, 3,769,301, 3,814,609, 3,837,862 and 4,026,707, British Patents 1,344,281 and 1,507,803, Japanese Patent Specifications Nos. 4936/68 and 12375/78 and Japanese Patent Applications (OPI) Nos. 110618/77 and 109925/77.

Dyes which do not themselves have spectral sensitizing activity or substances which do not absorb substantially any visible rays but have supersensitizing activity may be added to the emulsions together with the sensitizing dyes.

The present invention will be explained in more detail with reference to the following examples.

EXAMPLE 1

35 ml of ethyl acetate and 12 ml of comparative compound A (dielectric constant: 3.61) were added to 24.0 g of yellow coupler (Y-1) and dissolved, and the resulting solution was added to 160 ml of a 12% aqueous gelatin solution containing 12 ml of 20% sodium dodecylbenzenesulfonate and emulsified and dispersed with a high-speed stirrer to obtain an emulsified dispersion containing dispersed grains having an average grain diameter of 0.46 µm. (The grain size was measured using a laser beam scattering grain size measuring apparatus.) The entire amount of the resulting dispersion was added to a silver chlorobromide emulsion containing 80% Br (Ag content: 70 g/kg), and the resulting emulsion was coated on a paper support both sides of which were laminated with polyethylene, the coating amount of Ag was 0.31 g/m², and a gelatin layer was provided on the thus-coated layer to obtain Sample No. 1. Sodium 1-hydroxy-3,5-dichloro-s-triazine was used as a gelatin hardener.

Then, other emulsified dispersions shown in Table 1 below were prepared in the same manner as before except that the compound shown below was used in place of Comparative Compound A and that the emulsification conditions were varied (by changing the rotation number of the stirring blades in the emulsifier and the time for emulsification), and thus, in the same manner as in the formation of Sample No. 1, Sample Nos. 2 to 12 were obtained. The compounds used were as follows:

Comparison compound B (dielectric constant: 3.63)

Compound (S-7) (dielectric constant: 4.80)

Compound (S-9) (dielectric constant: 4.46)

Compound (S-16) (dielectric constant: 7.33)

Compound (S-25 dielectric constant: 6.45)

Further, Sample Nos. 13 to 20 and Sample Nos. 21 to 28 were formed in the same manner as Sample Nos. 1 to 12 except that a magenta coupler (M-1) and a cyan coupler (C-1) were used instead of a yellow coupler (Y-1), respectively. In the case of using the magenta coupler, the amount of the coupler coated was 0.37 g/m² and the coating amount of Ag of the silver chlorobromide emulsion (Br content: 75 mol%) was 0.20 g/m², and in the case of using the cyan coupler, the amount of the coupler coated was 0.33 g/m² and the coating amount of Ag of the silver chlorobromide emulsion (Br content: 70 mol%) was 0.28 g/m². Yellow coupler (Y-1) Magenta coupler (M-1) Cyan coupler (C-1) Comparison compound A (dielectric constant: 3.61)

Comparison compound B (dielectric constant: 3.63)

O=P(OC₁₈H₃₅)₃

These samples were subjected to gradation exposure for sensitometry and then processed in the following steps (A) or (B), each using the following color developers (A) and (B), respectively. The steps (A) and (B) were the same, with only the use of color developers (A) or (B) differing in each step. The evaluation of the photographic properties was carried out using the two characteristics of maximum density (Dmax) and minimum density (Dmin).

The results are shown in Table 1. Processing stage Temperature (ºC) Time (min) Development Bleach-fixation Washing

Composition of developers: Color developer (A):

3Well . Nitrilotriacetic acid 2.0 g

Benzyl alcohol 15 ml

Diethylene glycol 10 ml

Na₂SO₃ 2.0 g

KBr 0.5 g

Hydroxylamine sulfate 3.0 g

4-Amino-3-methyl-N-ethyl-N-[β- (methanesulfonamido)ethyl]-p- phenylenediamine sulfate 5.0 g

Na₂CO₃ (monohydrate) 30.0 g

Water to 1000 ml

(pH10.1)

Color developer (B):

3Well . Nitrilotriacetic acid 2.0 g

Na₂SO₃ 2.0 g

KBr 0.5 g

Hydroxylamine sulfate 3.0 g

4-Amino-3-methyl-N-ethyl-N-[β- (methanesulfonamido)ethyl]-p- phenylenediamine sulfate 5.0 g

Na₂CO₃ (monohydrate) 30.0 g

Water to 1000 ml

(pH10.1)

Composition of the bleach-fixing solution:

Ammonium thiosulfate (54 wt%) 150 ml

Na₂SO₃ 15 g

NH4[Fe(III) (EDTA)] 55 g

EDTA . 2Na 4g

Water to 1000 ml

(pH6.9) Table 1 Photographic characteristics Level Sample No. Coupler High boiling point organic solvent Average grain diameter of emulsion (µm) Note Comparison compound comparison invention Photographic characteristics Level Sample No. Coupler High boiling organic solvent Average grain diameter of the emulsion (um) Notes Comparison compound Comparison Invention Photographic characteristics Level Sample No. Coupler High boiling organic solvent Average grain diameter of the emulsion (um) Notes Comparison compound Comparison Invention

Table 1 demonstrates that the samples of the invention (Sample Nos. 6, 8, 10, 12, 16, 18, 20, 24, 26 and 28) had sufficient maximum density in both Step (A) and Step (B) using any of the yellow, magenta and cyan couplers, while the decrease in color density of the comparative samples (Sample Nos. 1 to 5, 7, 9, 11, 13 to 15, 17, 19, 21 to 23, 25 and 27) was particularly notable when processed in Step (B) without benzyl alcohol.

EXAMPLE 2

A multilayer color photographic paper according to the present invention was formed having layers as shown in the following Table 2, the layers being provided on a paper support laminated on both sides thereof with polyethylene.

This photosensitive material was designated as sample (a).

The coating solutions were prepared as follows:

Preparation of the coating solution for the first layer:

27.2 ml of ethyl acetate and 7.9 ml of solvent (c) were added to 19.1 g of yellow coupler (a) and 4.4 g of color image stabilizer (b) and dissolved. The resulting solution was added to 185 ml of 10% aqueous gelatin solution containing 16 ml of 10% sodium dodecylbenzenesulfonate and emulsified in a homogenizer to obtain an emulsified dispersion having an average grain diameter of 0.15 µm. (The grain size was measured using a laser beam scattering grain sizer.)

On the other hand, the following blue-sensitive sensitizing dye was added to a silver chlorobromide emulsion (silver bromide content: 80 mol%, silver content: 70 g/kg) in a amount of 7.0 x 10⁻⁴ mol per mol of silver chlorobromide to obtain 90 g of a blue-sensitive emulsion.

The emulsified dispersion and the emulsion were mixed and dissolved, and the gelatin concentration was adjusted as shown in Table 2 to obtain a coating solution for the first layer.

The other coating solutions for the second to seventh layers were prepared in the same way as the coating solution for the first layer.

Sodium 1-hydroxy-3,5-dichloro-s-triazine was used as gelatin hardener in each layer,

The spectral sensitizer used in each emulsion was as follows. Blue-sensitive emulsion layer: (7.0 × 10⊃min;⊃4; mol per mol of silver halide was added) Green sensitive emulsion layer: (4.0 × 10⁻⁴ mol per mol of silver halide was added) (7.0 × 10⁻⁴ mol per mol of silver halide was added) Red-sensitive emulsion layer: (1.0 × 10⊃min;⊃4; mol per mol of silver halide was added)

The antihalation dye used in each layer was as follows: green-sensitive emulsion layer: red-sensitive emulsion layer:

The couplers and other compounds used in the present examples have the following structural formulas: (a) Yellow coupler (Y-35) : (b) Color image stabilizer: (c) Solvent : (d) Anti-colour discolouration agents: (e) Magenta coupler (M-23) : (f) Color image stabilizer : (g) Solvent mixture (2/1 by weight) of (C�8H₁₇O)₃-P=O and (h) Ultraviolet absorber : mixture (1/5/3 molar ratio) of the following: (i) Anti-colour discolouration agents:

(i) Solvent :

(iso-C�9;H₁�9;)₃-P=O (k) Cyan coupler : (l) Colour image stabilizer: mixture (1/3/3 molar ratio) of the following:

(m) Solvent :

(S-16)

TABLE 2 Seventh layer: protective layer

Gelatin 1.33 g/m²

Acrylic modified polyvinyl alcohol copolymer (modification level: 17%) 0.17 g/m²

Sixth layer: UV-absorbing layer

Gelatin 0.54 g/m²

UV absorber (h) 0.21 g/m²

Solvent (j) 0.09 ml/m²

Fifth layer: Red-sensitive layer

Silver chlorobromide emulsion (silver bromide: 70 mol%) Ag 0.26 g/m²

Gelatin 0.98 g/m²

Cyan coupler (k) 0.34 g/m²

Color image stabilizer (l) 0.17 g/m²

Solvent (m) 0.23 ml/m²

Fourth layer: UV-absorbing layer

Gelatine 1.60 g/m²

UV absorber (h) 0.62 g/m²

Anti-colour discolouration agent (i) 0.05 g/m²

Solvent (j) 0.26 ml/m²

Third layer: Green-sensitive layer

Silver chlorobromide emulsion (silver bromide: 75 mol%) Ag 0.16 g/m²

Gelatine 1.80 g/m²

Magenta coupler (s) 0.34 g/m²

Color image stabilizer (f) 0.20 g/m²

Solvent (g) 0.68 ml/m²

Second layer: anti-color discoloration layer

Gelatin 0.99 g/m²

Anti-colour discolouration agent (d) 0.08 g/m²

First layer: Blue-sensitive layer

Silver chlorobromide emulsion (silver bromide: 80 mol%) Ag 0.30 g/m²

Gelatin 1.86 g/m²

Yellow coupler (a) 0.82 g/m²

Color image stabilizer (b) 0.19 g/m²

Solvent (c) 0.34 ml/m²

Carrier:

Polyethylene laminated paper (containing a white pigment TiO₂ and bluish dye ultramarine in the polyethylene on the side bearing the first layer).

Next, the following photographic light-sensitive material samples (b) to (d) were formed.

Sample (b):

This was the same sample as sample (a) except that the average grain sizes of the emulsified dispersions in each of the first, third and fifth layers were varied as shown in Table 3 below by controlling the emulsification conditions of the dispersions.

Sample (c):

This was the same sample as sample (a) with the except that the solvents for the first, third and fifth layers were replaced by the same volume of control compound A.

Sample (d):

This was the same sample as sample (c) except that the mean grain sizes of the emulsified dispersions for each of the first, third and fifth layers were varied as shown in Table 3 by controlling the emulsification conditions of the dispersions.

These samples were subjected to gradation exposure for sensitometry through the blue, green and red filters, respectively, using a sensitometer with a light source with a color temperature of 3200ºK. The exposure time was 0.5 s and the exposure amount was 250 CMS.

The exposed samples were then processed with a color developer (A) or (B) in the following steps (A) or (B) as shown below.

Photographic processing included color development, bleach-fixation and washing; and the photographic characteristics of the samples were determined by varying the development 1 min, 2 min and 3 min.

Steps (A) and (B) were the same except for the use of color developer (A) or (B) in each step.

The evaluation of the photographic properties was based on four characteristics, namely the relative sensitivity, gradation, maximum density (Dmax) and minimum density (Dmin).

The relative sensitivity is represented by a relative value based on the index value (100) of the sensitivity of each sample processed in the step (A) in which the color development time was 2 min. The sensitivity was designated by the relative value of the reciprocal of the exposure amount required to obtain a density comprising the minimum density plus 0.5.

The gradation was designated by the density difference between the sensitivity point and the point that includes the logarithm of the exposure amount (logE) plus 0.5.

The results are shown in Table 3. Processing stage Temperature (ºC) Time (min) Development Bleach-fixation Washing

Composition of developers: Color developer (A):

3Na . Nitrilotriacetate 2.0 g

Benzyl alcohol 15 ml

Diethylene glycol 10 ml

Na₂SO₃ 2.0 g

KBr 0.5 g

Hydroxylamine sulfate 3.0 g

4-Amino-3-methyl-N-ethyl-N-[β- (methanesulfonamido)ethyl]-p- phenylenediamine sulfate 5.0 g

Na₂CO₃ (monohydrate) 30.0 g

Water to 1000 ml

(pH10.1)

Color developer (B):

3Na . Nitrilotriacetate 2.0 g

Na₂SO₃ 2.0 g

KBr 0.5 g

Hydroxylamine sulfate 3.0 g

4-Amino-3-methyl-N-ethyl-N-[β- (methanesulfonamido)ethyl]-p- phenylenediamine sulfate 5.0 g

Na₂CO₃ (monohydrate) 30.0 g

Water to 1000 ml

(pH10.1)

Composition of the bleach-fixing solution:

Ammonium thiosulfate (54 wt%) 150 ml

Na₂SO₃ 15 g

NH4[Fe(III)(EDTA)] 55 g

EDTA . 2NA 4g

Water to 1000 ml

(pH6.9) Table 3 Stage Development time Sample *Layer Average grain size of emulsified dispersion (µm) Invention Comparison Note* : B: first layer in samples (a) to (d), G: third layer in samples (a) to (d), R: fifth layer in samples (a) to (d), 1: relative sensitivity, 2: gradation

Table 3 shows that the photographic light-sensitive material sample (a) of the present invention is superior to the other comparative photographic light-sensitive material samples (b) to (d) in that the difference in photographic properties (including relative sensitivity, gradation and maximum density) between processing (A) and processing (B) is small, and therefore even in processing (B) the same result as in processing (A) without benzyl alcohol can be obtained.

In addition, good photographic properties could be obtained with the development with a development time of 2 min in the present sample (a).

Example 3

Samples (e), (f), (g) and (h) were prepared in the same manner as previously described for samples (a), (b), (c) and (d), respectively, except that silver halide emulsions used for the first layer (blue-sensitive layer), the third layer (green-sensitive layer) and the fifth layer (red-sensitive layer) were a silver chlorobromide emulsion (silver bromide: 1 mol%, cubic shape, average grain size: 1.0 µm), a silver chlorobromide emulsion (silver bromide: 1.5 mol%, cubic shape, average grain size: 0.4 µm) and a silver chlorobromide emulsion (silver bromide: 1.5 mol%, cubic shape, average grain size: 0.5 µm), respectively.

The samples were exposed as in Example 2 and then processed in the following steps (c) or (d) with color developers (C) or (D) as shown below to obtain color images.

Stages (C) and (D) were the same except for the use of color developers (C) or (D) in each stage.

The evaluation of the photographic characteristics is carried out based on two aspects, the maximum density (Dmax) and the minimum density (Dmin).

The results are shown in Table 4 below. Processing stage Temperature (ºC) Time (s) Development Bleach-fixation Washing* Drying *: A four-stage countercurrent system was used for the washing stage.

Composition of developers: Color developer (C):

Ethylenediamine-N,N,N',N'-tetramethylenephosphonic acid 1.5 g

1,4-Diazabicyclo[2,2,2]octane 6.0 g

Sodium chloride 1.4 g

Potassium carbonate 25 g

N-Ethyl-N-(β-methanesulfonamidoethyl)-3-methyl-4-aminoaniline sulfate 5.0 g

N,N-Diethylhydroxylamine 4.2 g

Optical brightener (4,4-diaminostilbene type) 2.0 g

Benzyl alcohol 10.0 ml

Water to 1000 ml

(pH10.10)

Colour developer (D):

This was the same as Color Developer (C) with the exception that it did not contain benzyl alcohol.

Composition of the bleach-fixing solution:

Ammonium thiosulfate (70 wt%) 100 ml

Na₂SO₃ 18 g

NH4[Fe(III) (EDTA) 55 g

EDTA . ONa 3g

Ammonium bromide 40 g

Glacial acetic acid 8g

Water to 1000 ml

(pH5.5)

Watering solution:

Demineralized water (containing no more than 3 ppm calcium or magnesium.) Table 4 Stage Sample *Layer Average grain size of the emulsified dispersion (µm) Invention Comparison *: B: 1st layer in samples (e) to (h) G: 3rd layer in samples (e) to (h) R: 5th layer in samples (e) to (h)

Table 4 shows that the photographic light-sensitive material sample (e) of the present invention is superior to the other comparative photographic light-sensitive material samples (f) to (h) in that the coloring property is high, and the difference in the photographic properties of the step (C) and those of the step (D) is small.

In addition, good photographic properties could be obtained with the development with a short development time and without benzyl alcohol in the present sample (e).

Claims (27)

1. A process for producing color images, wherein a silver halide color photographic material comprising at least one silver halide emulsion layer on a reflective support, which comprises an oleophilic fine grain dispersion containing a coupler capable of forming a color upon coupling with the oxidation product of an aromatic primary amine developing agent, and at least one high-boiling organic solvent selected from the group consisting of the following formulas (I), (II), (III), (IV) and (V): wherein W₁, W₂ and W₃ each represent a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, aryl or heterocyclic group; W₄ is W₁, O-W₁ or S-W₁; n is an integer of 1 to 5, and when n is 2 or more, W₄ may be the same or different; and in formula (V), W₁ and W₂ may be bonded to each other to form a condensed ring; imagewise exposed and then developed with a color developer containing an aromatic primary amine developing agent but substantially no benzyl alcohol, characterized in that the oleophilic fine grains have an average grain size of 0.25 µm or less, the organic solvents have a dielectric constant of 4.0 or more (25°C, 10 kHz) and the imagewise exposed photographic material is developed for 2 min 30 s or less. 2. The process according to claim 1, wherein W₁, W₂ and W₃ in the formulas (I) to (V) each represent an unsubstituted alkyl, cycloalkyl, alkenyl, aryl or heterocyclic group. 3. The process according to claim 1, wherein W₁, W₂ and W₃ in the formulas (I) to (V) each represent an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group or a heterocyclic group substituted with one or more substituents with one or more linking groups selected from the group consisting of -COO-, -CON, -R⁸N and -O-, wherein R⁸ represents a divalent to hexavalent group derived from a phenyl group by removing one or more hydrogen atoms. 4. The process according to claim 1, wherein W₁, W₂, W₃ or W₄ in the formulae (I) to (V) represents a linear or branched alkyl group optionally substituted with one or more substituents selected from a halogen atom, a cycloalkyl group, an aryl group and an ester group. 5. The process according to claim 1, wherein W₁ and W₂ in the formula (V) are bonded together to form an oxirane ring, an oxolane ring or an oxane ring. 6. The process according to claim 1, wherein the high-boiling organic solvents of formulas (I) to (V) have a dielectric constant of 5.00 or more at 25°C, 10 kHz, and a viscosity of 20 mPa.s or more at 25°C. 7. Process according to claim 1, wherein one or more high-boiling organic solvents of the formulas (I) and (II) are used. 8. The process according to claim 1, wherein the high-boiling organic solvent of formula (I) is used. 9. The method according to claim 1, wherein the concentration of benzyl alcohol in the color developer is 0.5 ml/l or less. 10. The method of claim 1, wherein the color developer does not contain benzyl alcohol. 11. The method according to claim 1, wherein the color development time is 1 to 2 minutes. 12. The process according to claim 1, wherein the oleophilic fine grains have an average grain size of 0.05 µm to 0.20 µm. 13. The method according to claim 1, wherein the color developer is an alkaline aqueous solution mainly comprising an aromatic primary amine type color developing agent. 14. The method according to claim 1, wherein the processing temperature of the color developer is 30 to 50°C. 15. The method according to claim 1, wherein the processing temperature of the color developer is 33 to 45°C. 16. The process according to claim 12, wherein the high-boiling organic solvent of formula (I) is used. 17. The method of claim 12, wherein the color developer does not contain benzyl alcohol. 18. A process according to claim 4, wherein the ester group is a 2-basic acid ester group, a group derived from lactate, a group derived from citrate, a group derived from malate or a group derived from tartrate. group and -CH₂-C(COOC₈H₁₇)(OH)CH₂COOC₈H₁₇. 19. The process of claim 1, wherein the weight ratio of the high-boiling organic solvent to the coupler is from 0.05/1 to 20/1. 20. The method according to claim 1, wherein the silver halide color photographic material further contains an alkali metal halide or an organic fog inhibitor. 21. The method according to claim 1, wherein the silver halide emulsion layer contains silver halide grains of cubic or tetradecahedral crystal form. 22. The method according to claim 1, wherein the silver halide emulsion layer contains a silver halide emulsion having a variation coefficient of 20% or less. 23. The method of claim 22, wherein the coefficient of variation is 15% or less. 24. The process of claim 1, wherein the silver halide emulsion layer contains a silver chlorobromide having from 20 to 98 mol% silver bromide content but substantially no iodide. 25. The method of claim 1, wherein the silver halide emulsion layer contains a silver chloride or a silver chlorobromide having a silver chloride content of more than 80 mol%. 26. A process according to claim 1, wherein the silver halide emulsion layer comprises a silver halide emulsion mainly having a latent image on its surface formed by exposure. 27. The process of claim 1 wherein the aromatic primary amine developing agent is 3-methyl-4-amino-N-ethyl-N-β-hydroxyethylaniline or 3-methyl-4-amino-N-ethyl-N-β-methanesulfonamidoethylaniline.