EP0747762A1

EP0747762A1 - Silver halide color photographic light-sensitive elements having improved granularity

Info

Publication number: EP0747762A1
Application number: EP95108592A
Authority: EP
Inventors: Enzo Coraluppi; Ferdinando Orengo
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: Tulalip Consultoria Comercial SU
Priority date: 1995-06-06
Filing date: 1995-06-06
Publication date: 1996-12-11
Anticipated expiration: 2015-06-06
Also published as: JPH08328218A; EP0747762B1; JP3549982B2; DE69529977D1; DE69529977T2

Abstract

Silver halide photographic element comprising a support having coated thereon red-, green- and blue-sensitive silver halide emulsion layers comprising, respectively, cyan, magenta and yellow dye-forming couplers, wherein the green-sensitive layer comprises three green-sensitive layers having different sensitivity, an uppermost green-sensitive layer being more sensitive than an intermediate green-sensitive layer which is more sensitive than a lowermost green-sensitive layer, the layers arranged with the lowermost green-sensitive layer being closer to the support, the intermediate green-sensitive layer being adjacent said lowermost green-sensitive layer and the uppermost green-sensitive layer being above the intermediate green-sensitive layer, characterized in that the uppermost green-sensitive emulsion layer comprises 4-equivalent 5-pyrazolone magenta dye-forming couplers, and the intermediate and the lowermost green-sensitive emulsion layers comprise 2-equivalent 4-arylthio-5-pyrazolone magenta dye-forming couplers.

Description

FIELD OF THE INVENTION

The present invention relates to silver halide color photographic light-sensitive elements containing photographic couplers and, more particularly, 4-equivalent and 2-equivalent 5-pyrazolone magenta dye-forming couplers.

BACKGROUND OF THE INVENTION

It is well known that color photographic light-sensitive elements, using the subtractive process for color reproduction, comprise silver halide emulsion layers selectively sensitive to blue, green and red light and associated with yellow, magenta and cyan dye-forming couplers which form (upon reaction with an oxidized primary amine type color developing agent) the complementary color thereof. For example, an acylacetanilide type coupler is used to form a yellow color image; a 5-pyrazolone, pyrazolotriazole, cyanacetophenone or indazolone type coupler is used to form a magenta color image; and a phenol type, such as a phenol or naphthol, coupler is used to form a cyan color image.
Usually, the color photographic light-sensitive elements comprise non-diffusible couplers incorporated independently in each of the light-sensitive layers of the material (incorporated coupler materials). Therefore, a color photographic light-sensitive element usually comprises 1) a blue-sensitive silver halide emulsion layer (or layers) which contains a yellow dye-forming coupler and which is mainly sensitive to blue light (substantially to wavelengths less than about 500 nm); 2) a green-sensitive silver halide emulsion layer (or layers) which contains a magenta dye-forming coupler and which is mainly sensitive to green light (substantially to wavelengths of about 500 to 600 nm); and 3) a red-sensitive silver halide emulsion layer (or layers) which contains a cyan dye-forming coupler and which is mainly sensitive to red light (substantially to wavelengths longer than about 590 nm).
The silver halide emulsions used in the past for such photographic elements were the so-called mixed emulsions, that is, emulsions comprising a combination of a more sensitive emulsion (containing coarse silver halide grains) and a less sensitive emulsion (containing fine silver halide grains) whereby a straight density-log exposure curve could be obtained for each blue-, green- and red-sensitive layer.
Since granularity of the dye image in color photographic elements depends mainly upon the size of the silver halide grains employed, attempts to increase the sensitivity of the color photographic material by increasing the size of the silver halide grains (sensitivity of silver halide grains generally is proportional to the size of the silver halide grains) caused a coarsening of the granularity of the dye image.
As a method for improving sensitivity, a technique has been known in which the regular layer sequence of having respective red-sensitive, green-sensitive and blue-sensitive silver halide emulsion layers is provided by subdividing a part or whole of each of the emulsion layers into higher and lower sensitivity emulsion layers, each subdivided layer containing a color coupler forming substantially the same hue as the other subdivided layer and wherein these layers are coated adjacent to each other.
For example, GB 818,687 describes a method for increasing sensitivity in multilayer color photographic elements in which the emulsion layer which is applied closest to the support consists of two partial layers sensitized to the same region of the spectrum, the lower layer consisting of a less sensitive silver halide emulsion layer and the upper layer consisting of a more sensitive silver halide emulsion, both partial layers containing color-forming couplers in the same concentration. An element of this type has, however, the disadvantage that the increase in sensitivity is accompanied by an increase of granularity.
To overcome this disadvantage and lower the granularity of color images, GB 923,045 describes a method for increasing the sensitivity of a color photographic element without coarsening the granularity of the dye image by providing an uppermost more sensitive emulsion layer and a lowermost less sensitive emulsion layer, both layers being sensitive to the same region of the visible spectrum and each containing non-diffusing color couplers, with the maximum color density of the more sensitive emulsion layer being adjusted to be lower than that of the less sensitive emulsion layer, in particular being lower in an amount from 0.20 to 0.60.
US 3,516,831 describes a process for improving the sharpness of the color image, according to which two layers which are sensitized to the same spectral region of the spectrum contain different couplers, the more sensitive emulsion layer containing 4-equivalent couplers and the less sensitive emulsion layer 2-equivalent couplers.
Both processes described in GB 923,045 and US 3,516,831 have numerous disadvantages, for example a worsening of granularity in high-sensitivity photographic elements. A process for improving granularity is described in US 3,726,681 wherein granularity of high-sensitivity photographic elements is improved by using a coupler having a fast coupling reaction rate in a more sensitive silver halide emulsion layer and a coupler having a slow coupling reaction rate in a less sensitive silver halide emulsion layer. Since, however, sharpness is not sufficiently improved, EP 107,112 describes a color photographic element in which at least one of the silver halide emulsion layers is composed of two silver halide emulsion layers sensitive to the same color, the more sensitive layer containing a high reaction rate coupler, and the less sensitive silver halide emulsion layer containing a low reaction rate coupler in a range of 1/1.3 to 1/15 of that of the high reaction rate coupler and a diffusible DIR coupler. The purpose of DIR couplers is to help in reducing graininess and improve sharpness of the image due to intralayer or intraimage effects (that is in the same layers or the same dye image) and improve color reproduction due to interlayer or interimage effects (that is effect between different layers or different dye images).
Recently, the picture size of photographic films has been reduced to miniaturize photo cameras, and silver halide grains have become coarser to increase sensitivity of photographic elements. Therefore, the degrading tendency of the granularity has been increased, even if the aforesaid double layer system is used.
US 3,843,369 describes a method for further increasing the sensitivity of a color photographic element by providing three emulsion layers sensitive to the same spectral region of visible light, the uppermost silver halide emulsion layer having the highest light sensitivity and the lowermost silver halide emulsion layer having the lowest light sensitivity, the uppermost and the intermediate layer each having a maximum density of 0.6 or less.
US 4,582,780 describes a method for increasing sensitivity and improving adjacency effects by providing three emulsion layers sensitive to the same spectral region of visible light, the uppermost silver halide emulsion layer having the highest light sensitivity and the lowermost silver halide emulsion layer having the lowest light sensitivity, wherein the maximum color density of the uppermost silver halide emulsion layer, after color development, is lower than 0.60 and the maximum color densities of both the intermediate and the lowermost silver halide emulsion layers, after color development, are each higher than 0.60.
EP 583,020 discloses a technique for improving granularity by providing a multilayer color photographic elements comprising a plurality of blue, green and three red sensitive silver halide emulsion layers, the layers being arranged on the support in the sequence: a red least sensitive layer, a green least sensitive layer, a red mid-sensitive layer, a red most sensitive layer, a green most sensitive layer, a blue most sensitive layer, and a blue least sensitive layer.
EP 608,464 discloses a technique for enhancing the speed-granularity relationship of dye images by providing multicolor photographic elements containing blue, green and red sensitive layer units wherein at least one layer unit contains three superimposed silver halide emulsion layers of different sensitivity comprising silver bromoiodide tabular grains of different iodide content.
It is known that 2-equivalent 5-pyrazolone magenta couplers having an arylthio group attached to the 4-position of the pyrazolone ring have a number of advantages compared to 4-equivalent 5-pyrazolone magenta couplers in which the 4-position of the pyrazolone ring is free (that is having only hydrogen atoms). For example, 2-equivalent 5-pyrazolone couplers require only two equivalent of silver to produce each molecule of dye, are less sensitive to certain chemical vapors, for example formaldehyde, and have high dye light and dye dark stability. However, 2-equivalent 5-pyrazolone magenta couplers have the disadvantage that they may cause worsening of granularity.

SUMMARY OF THE INVENTION

The present invention relates to a multilayer color photographic element comprising a support having coated thereon red-, green- and blue-sensitive silver halide emulsion layers comprising, respectively, cyan, magenta and yellow dye-forming couplers, wherein the green-sensitive layer comprises three green-sensitive layers having different sensitivity, an uppermost green-sensitive layer being more sensitive than an intermediate green-sensitive layer which is more sensitive than a lowermost green-sensitive layer, the layers arranged with the lowermost green-sensitive layer being closer to the support, the intermediate green-sensitive layer being adjacent said lowermost green-sensitive layer and the uppermost green-sensitive layer being above the intermediate green-sensitive layer, characterized in that the uppermost green-sensitive emulsion layer comprises 4-equivalent 5-pyrazolone magenta dye-forming couplers, and the intermediate and the lowermost green-sensitive emulsion layers comprise 2-equivalent 4-arylthio-5-pyrazolone magenta dye-forming couplers.
The color photographic elements containing the aforesaid layer arrangement provide good speed-granularity relationship.

DETAILED DESCRIPTION OF THE INVENTION

In particular, said 2-equivalent 4-arylthio-5-pyrazolone magenta coupler for use in this invention may be represented by 1-phenyl-3-anilino-4-phenylthio-5-pyrazolone magenta couplers of the following formula (I):
wherein

a represents an integer from 0 to 3,
b represents an integer from 0 to 2,
R₁ and R₂ are each individually hydrogen, alkyl, alkoxy, halogen, aryl, aryloxy, acylamino, sulfonamido, sulfamoyl, carbamoyl, arylsulfonyl, aryloxycarbonyl, alkoxycarbonyl, alkoxysulfonyl, aryloxysulfonyl, alkylureido, arylureido, nitro, cyano, hydroxyl or carboxy group,
R₃ is halogen atom, alkyl group or aryl group,
X is a direct link or a linking group,
Ball is a ballasting group of such size and configuration as to render a group to which it is attached non-diffusible in photographic coatings, and
the sum of the sigma values of R₁, R₃ and X-Ball is less than 1.3.

In the above formula, examples of R₁ and R₂ include hydrogen; alkyl group, including straight or branched chain alkyl group, such as alkyl group containing 1 to 8 carbon atoms, for example methyl, trifluoromethyl, ethyl, butyl, and octyl; alkoxy group, such as an alkoxy group having 1 to 8 carbon atoms, for example methoxy, ethoxy, propoxy, 2-methoxyethoxy, and 2-ethylhexyloxy; halogen, such as chlorine, bromine, and fluorine; aryl group, such as phenyl, naphthyl, and 4-tolyl; aryloxy group, such as phenoxy, p-methoxyphenoxy, p-methylphenoxy, naphthyloxy, and tolyloxy; acylamino group, such as acetamido, benzamido, butyramido, and t-butylcarbonamido; sulfonamido group, such as methylsulfonamido, benzenesulfonamido, and p-toluylsulfonamido; sulfamoyl group, such as N-methylsulfamoyl, N,N-diethylsulfamoyl, and N,N-dimethylsulfamoyl; carbamoyl group, such as N-methylcarbamoyl, and N,N-dimethylcarbamoyl; arylsulfonyl, such as tolylsulfonyl; aryloxycarbonyl group, such as phenoxycarbonyl; alkoxycarbonyl group, such as alkoxycarbonyl group containing 2 to 10 carbon atoms, for example methoxycarbonyl, ethoxycarbonyl, and benzyloxycarbonyl; alkoxysulfonyl group, such as alkoxysulfonyl group containing 2 to 10 carbon atoms, for example methoxysulfonyl, octyloxysulfonyl, and 2-ethylhexylsulfonyl; aryloxysulfonyl group, such as phenoxysulfonyl; alkylureido group, such as N-methylureido, N,N-dimethylureido, and N,N-dibutylureido; arylureido group, such as phenylureido; nitro, cyano, hydroxyl and carboxy group.
Examples of R₃ include halogen, such as chlorine, bromine, and fluorine; alkyl group, including straight or branched chain alkyl group, such as alkyl group containing 1 to 8 carbon atoms, for example methyl, trifluoromethyl, ethyl, butyl, and octyl; aryl group, such as phenyl, naphthyl, and 4-tolyl.
"Ball" is a ballasting group, i.e., an organic group of such size and configuration as to render a group to which it is attached non-diffusible from the layer in which is coated in a photographic element. Said ballasting group may include an organic hydrophobic residue having 8 to 32 carbon atoms bonded to the coupler either directly or through a divalent linking group X, such as an alkylene, imino, ether, thioether, carbonamido, sulfonamido, ureido, ester, imido, carbamoyl, and sulfamoyl group. Specific examples of suitable ballasting groups include alkyl groups (linear, branched, or cyclic), alkenyl groups, alkoxy groups, alkylaryl groups, alkylaryloxy groups, acylamidoalkyl groups, alkoxyalkyl groups, alkoxyaryl groups, alkyl groups substituted with an aryl group ar a heterocyclic group, aryl groups substituted with an aryloxyalkoxycarbonyl group, and residues containing both an alkenyl or alkenyl long-chain aliphatic group and a carboxy or sulfo water-soluble group, as described, for example, in US 3,337,344, 3,418,129, 3,892,572, 4,138,258, and 4,451,559, and in GB 1,494,777.
When the term "group" or "residue" is used in this invention to describe a chemical compound or substituent, the described chemical material includes the basic group or residue and that group or residue with conventional substitution. Where the term "moiety" is used to describe a chemical compound or substituent, only the unsubstituted chemical material is intended to be included. For example, "alkyl group" includes not only such alkyl moiety as methyl, ethyl, butyl, octyl, stearyl, etc., but also moieties bearing substituent groups such as halogen, cyano, hydroxyl, nitro, amino, carboxylate, etc. On the other hand, "alkyl moiety" includes only methyl, ethyl, stearyl, cyclohexyl, etc.
In the present invention, the sum of sigma values of substituents on the 1-phenyl and 3-anilino groups, such as R₁, R₃ and -X-Ball is less than 1.3. The values of sigma constants can be easily found in the published literature (see, for example, "The Chemists' Companion", A.J. Gordon and R.A. Ford, John Wiley & Sons, New York, 1972, "Progress in Physical Organic Chemistry", V. 13, R.W. Taft, John Wiley & Sons, New York, "Substituents Constants for Correlation Analysis in Chemistry and Biology", C. Hansch and A.J. Leo, John Wiley & Sons, New York, 1979, and "Comprehensive Medicinal Chemistry", A.J. Leo, Pergamon Press, New York, V. 4, 1990), or can be calculated using the Medchem program (see "Comprehensive Medicinal Chemistry", A.J. Leo, Pergamon Press, New York, V. 4, 1990). Generally, sigma values increase with increasing electron withdrawing power of the substituent, with hydrogen = zero. For sigma values, only the atoms close to the phenyl ring have an electron withdrawing effect and remote atoms have no effect. Examples of sigma values for chemical groups or atoms are as follows: alkyl group = -017, chlorine atom = 0.23, alkoxycarbonyl group = 0.45, acylamino group = 0.21, sulfamoyl group = 0.57, alkylsulfonyl group = 0.78, and carbamoyl = 0.36.
Among the couplers described above, a preferred embodiment is represented by the above formula wherein the groups R₁ are chlorine atoms, a is 3, and the chlorine atoms are attached to the carbon atoms in position 2, 4 and 6 with respect to the carbon atom attached to the nitrogen atom.
A particularly preferred embodiment is represented by the above formula wherein the group R₃ is a chlorine atom.
Specific examples of 2-equivalent 1-phenyl-3-anilino-4-phenylthio-5-pyrazolone magenta couplers for use in the present invention are illustrated below, but the present invention should not be construed as being limited thereto.
Other illustrative couplers include:

wherein Q represents a coupling-off group according to the invention.
Illustrative coupling-off groups Q are as follows:
In particular, the 4-equivalent 5-pyrazolone magenta coupler for use in this invention may be represented by the following formula (II):
wherein R₁, R₃ and a have the same meaning as in formula (I), and n represents 0 or 1.
Among the 4-equivalent 5-pyrazolone magenta dye-forming couplers, a preferred embodiment is represented by the above formula (II) wherein the groups R₁ are chlorine atoms, a is 3, and the chlorine atoms are attached to the carbon atoms in position 2, 4 and 6 with respect to the carbon atom attached to the nitrogen atom.
Specific examples of 4-equivalent 5-pyrazolone magenta dye-forming couplers for use in the present invention are illustrated below, but the present invention should not be construed as being limited thereto.
In the present invention, the green-sensitive layer is composed of three silver halide emulsion layers sensitized to the same spectral region of the visible spectrum, the uppermost silver halide emulsion layer of which having the highest sensitivity and the lowermost silver halide emulsion layer having the lowest sensitivity, as described for example in US 3,843,369 and US 4,582,780. The three silver halide emulsions are arranged so that light travels through the uppermost highest sensitivity green-sensitive layer before striking the lowermost lowest sensitivity green-sensitive layer. The difference in sensitivity between the highest and the lowest green-sensitive layers, as referred to herein, is preferably such that extended latitude in the photographic element is achieved without an appreciable distortion of the shape of the sensitometric curve. Generally, this difference in sensitivity should be within the range of from about 0.2 to about 1 logE (E being dosage of exposure), and preferably will be about 0.3 to 0.6 logE. The intermediate medium sensitivity emulsion layer, having an intermediate sensitivity between the sensitivity of the uppermost highest sensitivity emulsion layer and the lowermost lowest sensitivity emulsion layer, generally has a sensitivity difference from the highest sensitivity emulsion layer of 0.1 to 0.55 logE and a sensitivity difference with the lowest sensitivity emulsion layer of 0.1 to 0.55 logE. Also, the uppermost highest sensitivity green-sensitive emulsion layer produces upon development a colored image of lower color density than the intermediate and the lowermost green-sensitive emulsion layers. Generally, the uppermost highest sensitivity green-sensitive emulsion layer is relatively "starved" with respect to its color coupler content in order to improve granularity of this layer (as disclosed by US 3,843,369 and US 4,582,780). That is, relatively smaller amounts of coupler are used in the highest sensitivity layer, such that, upon exposure and development, this layer produces a colored image which is less dense than that produced in the lowest sensitivity layer.
In the present invention, the uppermost highest sensitivity green-sensitive silver halide emulsion layer comprises the 4-equivalent 5-pyrazolone magenta coupler, while the intermediate medium sensitivity and the lowermost lowest sensitivity green-sensitive silver halide emulsion layers comprise the 2-equivalent 5-pyrazolone magenta coupler as described above. In the uppermost layer, the 4-equivalent 5-pyrazolone magenta dye-forming coupler is preferably used in an amount ranging from 0.01 to 0.5 mol per mol of silver halide, more preferably 0.02 to 0.1 mol, in the intermediate layer the 2-equivalent 5-pyrazolone magenta dye-forming coupler is preferably used in an amount ranging from 0.01 to 0.5 mol per mol of silver halide, more preferably 0.02 to 0.1 mol , and in the lowermost layer the 2-equivalent 5-pyrazolone magenta dye- forming coupler is preferably used in an amount ranging from 0.02 to 1.0 mol per mol of silver halide, more preferably 0.04 to 0.2 mol.
The color photographic elements of the present invention can be conventional photographic elements containing a silver halide as a light-sensitive substance.
The silver halides used in the multilayer color photographic elements of this invention may be a fine dispersion (emulsion) of silver chloride, silver bromide, silver chloro-bromide, silver iodo-bromide and silver chloro-iodo-bromide grains in a hydrophilic binder. Preferred silver halides are silver iodo-bromide or silver iodo-chloro-bromide containing 1 to 20% mole silver iodide. In silver iodo-bromide emulsions or silver iodo-chloro-bromide, the iodide can be uniformly distributed among the emulsion grains, or iodide level can varied among the grains. The silver halides can have a uniform grain size or a broad grain size distribution. The silver halide grains may be regular grains having a regular crystal structure such as cubic, octahedral, and tetradecahedral, or the spherical or irregular crystal structure, or those having crystal defects such as twin plane, or those having a tabular form, or the combination thereof.
The term "cubic grains" according to the present invention is intended to include substantially cubic grains, that is grains which are regular cubic grains bounded by crystallographic faces (100), or which may have rounded edges and/or vertices or small faces (111), or may even be nearly spherical when prepared in the presence of soluble iodides or strong ripening agents, such as ammonia. Particularly good results are obtained with silver halide grains having average grain sizes in the range from 0.2 to 3 µm, more preferably from 0.4 to 1.5 µm. Preparation of silver halide emulsions comprising cubic silver iodobromide grains is described, for example, in Research Disclosure, Vol. 184, Item 18431, Vol. 176, Item 17644 and Vol. 308, Item 308119.
Other silver halide emulsions for use in this invention are those which employ one or more light-sensitive tabular grain emulsions. The tabular silver halide grains contained in the emulsion of this invention have an average diameter:thickness ratio (often referred to in the art as aspect ratio) of at least 2:1, preferably 2:1 to 20:1, more preferably 3:1 to 14:1, and most preferably 3:1 to 8:1. Average diameters of the tabular silver halide grains suitable for use in this invention range from about 0.3 µm to about 5 µm, preferably 0.5 µm to 3 µm, more preferably 0.8 µm to 1.5 µm. The tabular silver halide grains suitable for use in this invention have a thickness of less than 0.4 µm, preferably less than 0.3 µm and more preferably less than 0.2 µm.
The tabular grain characteristics described above can be readily ascertained by procedures well known to those skilled in the art. The term "diameter" is defined as the diameter of a circle having an area equal to the projected area of the grain. The term "thickness" means the distance between two substantially parallel main planes constituting the tabular silver halide grains. From the measure of diameter and thickness of each grain the diameter:thickness ratio of each grain can be calculated, and the diameter:thickness ratios of all tabular grains can be averaged to obtain their average diameter:thickness ratio. By this definition, the average diameter:thickness ratio is the average of individual tabular grain diameter:thickness ratios. In practice, it is simpler to obtain an average diameter and an average thickness of the tabular grains and to calculate the average diameter:thickness ratio as the ratio of these two averages. Whatever the used method may be, the average diameter:thickness ratios obtained do not greatly differ.
In the silver halide emulsion layer containing tabular silver halide grains, at least 15%, preferably at least 25%, and, more preferably, at least 50% of the silver halide grains are tabular grains having an average diameter:thickness ratio of not less than 2:1. Each of the above proportions, "15%", "25%" and "50%" means the proportion of the total projected area of the tabular grains having a diameter:thickness ratio of at least 2:1 and a thickness lower than 0.4 µm, as compared to the projected area of all of the silver halide grains in the layer.
It is known that photosensitive silver halide emulsions can be formed by precipitating silver halide grains in an aqueous dispersing medium comprising a binder, gelatin preferably being used as a binder.
The silver halide grains may be precipitated by a variety of conventional techniques. The silver halide emulsion can be prepared using a single-jet method, a double-jet method, or a combination of these methods or can be matured using, for instance, an ammonia method, a neutralization method, an acid method, or can be performed an accelerated or constant flow rate precipitation, interrupted precipitation, ultrafiltration during precipitation, etc. References can be found in Trivelli and Smith, The Photographic Journal, Vol. LXXIX, May 1939, pp. 330-338, T.H. James, The Theory of The Photographic Process, 4th Edition, Chapter 3, US Patent Nos. 2,222,264, 3,650,757, 3,917,485, 3,790,387, 3,716,276, 3,979,213, Research Disclosure, Dec. 1989, Item 308119 "Photographic Silver Halide Emulsions, Preparations, Addenda, Processing and Systems", and Research Disclosure, Sept. 1976, Item 14987.
One common technique is a batch process commonly referred to as the double-jet precipitation process by which a silver salt solution in water and a halide salt solution in water are concurrently added into a reaction vessel containing the dispersing medium.
In the double jet method, in which alkaline halide solution and silver nitrate solution are concurrently added in the gelatin solution, the shape and size of the formed silver halide grains can be controlled by the kind and concentration of the solvent existing in the gelatin solution and by the addition speed. Double-jet precipitation processes are described, for example, in GB 1,027,146, GB 1,302,405, US 3,801,326, US 4,046,376, US 3,790,386, US 3,897,935, US 4,147,551, and US 4,171,224.
The single jet method in which a silver nitrate solution is added in a halide and gelatin solution has been long used for manufacturing photographic emulsion. In this method, because the varying concentration of halides in the solution determines which silver halide grains are formed, the formed silver halide grains are a mixture of different kinds of shapes and sizes.
Precipitation of silver halide grains usually occurs in two distinct stages. In a first stage, nucleation, formation of fine silver halide grain occurs. This is followed by a second stage, the growth stage, in which additional silver halide formed as a reaction product precipitates onto the initially formed silver halide grains, resulting in a growth of these silver halide grains. Batch double-jet precipitation processes are typically undertaken under conditions of rapid stirring of reactants in which the volume within the reaction vessel continuously increases during silver halide precipitation and soluble salts are formed in addition to the silver halide grains.
In order to avoid soluble salts in the emulsion layers of a photographic material from crystallizing out after coating and other photographic or mechanical disadvantages (stickiness, brittleness, etc.), the soluble salts formed during precipitation have to be removed.
In preparing the silver halide emulsions for use in the present invention, a wide variety of hydrophilic dispersing agents for the silver halides can be employed. As hydrophilic dispersing agent, any hydrophilic polymer conventionally used in photography can be advantageously employed including gelatin, a gelatin derivative such as acylated gelatin, graft gelatin, etc., albumin, gum arabic, agar agar, a cellulose derivative, such as hydroxyethylcellulose, carboxymethylcellulose, etc., a synthetic resin, such as polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, etc. Other hydrophilic materials useful known in the art are described, for example, in Research Disclosure, Vol. 308, Item 308119, Section IX.
The silver halide grain emulsion for use in the present invention can be chemically sensitized using sensitizing agents known in the art. Sulfur containing compounds, gold and noble metal compounds, and polyoxylakylene compounds are particularly suitable. In particular, the silver halide emulsions may be chemically sensitized with a sulfur sensitizer, such as sodium thiosulfate, allylthiocyanate, allylthiourea, thiosulfinic acid and its sodium salt, sulfonic acid and its sodium salt, allylthiocarbamide, thiourea, cystine, etc.; an active or inert selenium sensitizer; a reducing sensitizer such as stannous salt, a polyamine, etc.; a noble metal sensitizer, such as gold sensitizer, more specifically potassium aurithiocyanate, potassium chloroaurate, etc.; or a sensitizer of a water soluble salt such as for instance of ruthenium, rhodium, iridium and the like, more specifically, ammonium chloropalladate, potassium chloroplatinate and sodium chloropalladite, etc.; each being employed either alone or in a suitable combination. Other useful examples of chemical sensitizers are described, for example, in Research Disclosure 17643, Section III, 1978 and in Research Disclosure 308119, Section III, 1989.
The silver halide emulsion for use in the present invention can be spectrally sensitized with dyes from a variety of classes, including the polymethyne dye class, which includes the cyanines, merocyanines, complex cyanines and merocyanines, oxonols, hemioxonols, styryls, merostyryls, and streptocyanine.
The cyanine spectral sensitizing dyes include, joined by a methine linkage, two basic heterocyclic nuclei, such as those derived from quinoline, pyrimidine, isoquinoline, indole, benzindole, oxazole, thiazole, selenazole, imidazole, benzoxazole, benzothiazole, benzoselenazole, benzoimidazole, naphthoxazole, naphthothiazole, naphthoselenazole, tellurazole, oxatellurazole.
The merocyanine spectral sensitizing dyes include, joined by a methine linkage, a basic heterocyclic nucleus of the cyanine-dye type and an acidic nucleus, which can be derived from barbituric acid, 2-thiobarbituric acid, rhodanine, hydantoin, 2-thiohydantoin, 2-pyrazolin-5-one, 2-isoxazolin-5-one, indan-1,3-dione, cyclohexane-1,3-dione, 1,3-dioxane-4,6-dione, pyrazolin-3,5-dione, pentane-2,4-dione, alkylsulfonylacetonitrile, malononitrile, isoquinolin-4-one, chromane-2,4-dione, and the like.
One or more spectral sensitizing dyes may be used. Dyes with sensitizing maxima at wavelengths throughout the visible and infrared spectrum and with a great variety of spectral sensitivity curve shapes are known. The choice and relative proportion of dyes depends on the region of the spectrum to which sensitivity is desired and on the shape of the spectral sensitivity desired.
Examples of sensitizing dyes can be found in Venkataraman, The chemistry of Synthetic Dyes , Academic Press, New York, 1971, Chapter V, James, The Theory of the Photographic Process , 4th Ed., Macmillan, !977, Chapter 8, F.M.Hamer, Cyanine Dyes and Related Compounds , John Wiley and Sons, 1964, and in Research Disclosure 308119, Section III, 1989.
The silver halide emulsions for use in this invention can contain optical brighteners, antifogging agents and stabilizers, filtering and antihalo dyes, hardeners, coating aids, plasticizers and lubricants and other auxiliary substances, as for instance described in Research Disclosure 17643, Sections V, VI, VIII, X, XI and XII, 1978, and in Research Disclosure 308119, Sections V, VI, VIII, X, XI, and XII, 1989.
The silver halide emulsion for use in the present invention can be used for the manufacture of multilayer light-sensitive silver halide color photographic elements, such as color negative photographic elements, color reversal photographic elements, color positive photographic elements, false color address photographic elements (such as those disclosed in US 4,619,892) and the like, the preferred ones being color negative photographic elements.
Silver halide multilayer color photographic elements for use in the present invention usually comprise, coated on a support, at least two red sensitized silver halide emulsion layers associated with cyan dye-forming color couplers, three green sensitized silver halide emulsion layers associated with magenta dye-forming color couplers and at least two blue sensitized silver halide emulsion layers associated with yellow dye-forming color couplers. These elements additionally comprise other non-light sensitive layers, such as intermediate layers, filter layers, antihalation layers and protective layers, thus forming a multilayer structure. These color photographic elements, after imagewise exposure to actinic radiation, are processed in a chromogenic developer to yield a visible color image. The layer units can be coated in any conventional order, but in a preferred layer arrangement the red-sensitive layers are coated nearest the support and are overcoated by the green-sensitive layers, a yellow filter layer and the blue-sensitive layers.
Suitable color couplers are preferably selected from the couplers having diffusion preventing groups, such as groups having a hydrophobic organic residue of about 8 to 32 carbon atoms, introduced into the coupler molecule in a non-splitting-off position. Such a residue is called a "ballast group". The ballast group is bonded to the coupler nucleus directly or through an imino, ether, carbon-amido, sulfonamido, ureido, ester, imido, carbamoyl, sulfamoyl bond, etc. Examples of suitable ballasting groups are described in US patent 3,892,572.
Said non-diffusible couplers are introduced into the light-sensitive silver halide emulsion layers. On exposure and color development, said couplers give a color which is complementary to the light color to which the silver halide emulsion layers are sensitive. Consequently, at least one non-diffusible cyan image-forming color coupler, generally a phenol or an α-naphthol compound, is associated with red-sensitive silver halide emulsion layers, 4-equivalent and 2-equivalent 5-pyrazolone non-diffusible magenta image-forming color couplers are associated with green-sensitive silver halide emulsion layers, and at least one non-diffusible yellow image-forming color coupler, generally an acylacetanilide compound, is associated with blue-sensitive silver halide emulsion layers.
As known, color couplers may be 4-equivalent and/or 2-equivalent couplers, the latter requiring a smaller amount of silver halide for color production. As it is well known, 2-equivalent couplers derive from 4-equivalent couplers since, in the coupling position, they contain a substituent which is released during coupling reaction. 2-equivalent couplers which may be used in silver halide color photographic elements include both those substantially colorless and those which are colored ("masking couplers"). The 2-equivalent couplers also include white couplers which do not form any dye on reaction with the color developer oxidation products. The 2-equivalent color couplers include also DIR couplers which are capable of releasing a diffusing development inhibiting compound on reaction with the color developer oxidation products.
The most useful cyan-forming couplers are conventional phenol compounds and α-naphthol compounds. Examples of cyan couplers can be selected from those described in US patents 2,369,929; 2,474,293; 3,591,383; 2,895,826; 3,458,315; 3,311,476; 3,419,390; 3,476,563 and 3,253,924; in British patent 1,201,110, and in Research Disclosure 308119, Section VII, 1989.
The most useful magenta-forming couplers, which can be used in combination with the 4-equivalent and 2-equivalent magenta image-forming couplers described hereinbefore, are conventional pyrazolone type compounds, indazolone type compounds, cyanoacetyl compounds, pyrazolotriazole type compounds, etc., and particularly preferred are pyrazolone type compounds. Magenta-forming couplers are described for example in US patents 2,600,788, 2,983,608, 3,062,653, 3,127,269, 3,311,476, 3,419,391, 3,519,429, 3,558,319, 3,582,322, 3,615,506, 3,834,908 and 3,891,445,in DE patent 1,810,464, in DE patent applications 2,408,665, 2,417,945, 2,418,959 and 2,424,467; in JP patent applications 20,826/76, 58,922/77, 129,538/74, 74,027/74, 159,336/75, 42,121/77, 74,028/74, 60,233/75, 26,541/76 and 55,122/78, and in Research Disclosure 308119, Section VII, 1989.
The most useful yellow-forming couplers are conventional open-chain ketomethylene type couplers. Particular examples of such couplers are benzoylacetanilide type and pivaloyl acetanilide type compounds. Yellow-forming couplers that can be used are specifically described in US patents 2,875,057, 3,235,924, 3,265,506, 3,278,658, 3,369,859, 3,408,194, 3,415,652 3,528,322, 3,551,151, 3,682,322, 3,725,072 and 3,891,445, in DE patents 2,219,917, 2,261,361 and 2,414,006, in GB patent 1,425,020, in JP patent 10,783/76 and in JP patent applications 26,133/72, 73,147/73, 102,636/76, 6,341/75, 123,342/75, 130,442/75, 1,827/76, 87,650/75, 82,424/77 and 115,219/77, and in Research Disclosure 308119, Section VII, 1989.
Colored couplers can be used which include those described for example in US patents 3,476,560, 2,521,908 and 3,034,892, in JP patent publications 2,016/69, 22,335/63, 11,304/67 and 32,461/69, in JP patent applications 26,034/76 and 42,121/77 and in DE patent application 2,418,959. The light-sensitive silver halide color photographic element may contain high molecular weight color couplers as described for example in US Pat. No. 4,080,211, in EP Pat. Appl. No. 27,284 and in DE Pat. Appl. Nos. 1,297,417, 2,407,569, 3,148,125, 3,217,200, 3,320,079, 3,324,932, 3,331,743, and 3,340,376, and in Research Disclosure 308119, Section VII, 1989.
Colored cyan couplers can be selected from those described in US patents 3,934,802; 3,386,301 and 2,434,272, colored magenta couplers can be selected from the colored magenta couplers described in US patents 2,434,272; 3,476,564 and 3,476,560 and in British patent 1,464,361. Colorless couplers can be selected from those described in British patents 861,138; 914,145 and 1,109,963 and in US patent 3,580,722 and in Research Disclosure 308119, Section VII, 1989.
Also, couplers providing diffusible colored dyes can be used together with the above mentioned couplers for improving graininess and specific examples of these couplers are magenta couplers described in US Pat. No. 4,366,237 and GB Pat. No. 2,125,570 and yellow, magenta and cyan couplers described in EP Pat. No. 96,873, in DE Pat. Appl. No. 3,324,533 and in Research Disclosure 308119, Section VII, 1989.
Also, among the 2-equivalent couplers are those couplers which carry in the coupling position a group which is released in the color development reaction to give a certain photographic activity, e.g. as development inhibitor or accelerator or bleaching accelerator, either directly or after removal of one or further groups from the group originally released. Examples of such 2-equivalent couplers include the known DIR couplers as well as DAR, FAR and BAR couplers. Typical examples of said couplers are described in DE Pat. Appl. Nos. 2,703,145, 2,855,697, 3,105,026, 3,319,428, 1,800,420, 2,015,867, 2,414,006, 2,842,063, 3,427,235, 3,209,110, and 1,547,640, in GB Pat. Nos. 953,454 and 1,591,641, in EP Pat. Appl. Nos. 89,843, 117,511, 118,087, 193,389, and 301,477 and in Research Disclosure 308119, Section VII, 1989.
Examples of non-color forming DIR coupling compounds which can be used in silver halide color elements include those described in US patents 3,938,996; 3,632,345; 3,639,417; 3,297,445 and 3,928,041; in German patent applications S.N. 2,405,442; 2,523,705; 2,460,202; 2,529,350 and 2,448,063; in Japanese patent applications S.N. 143,538/75 and 147,716/75, in British patents 1,423,588 and 1,542,705 and 301,477 and in Research Disclosure 308119, Section VII, 1989.
In order to introduce the couplers into the silver halide emulsion layer, some conventional methods known to the skilled in the art can be employed. According to US patents 2,322,027, 2,801,170, 2,801,171 and 2,991,177, the couplers can be incorporated into the silver halide emulsion layer by the dispersion technique, which consists of dissolving the coupler in a water-immiscible high-boiling organic solvent and then dispersing such a solution in a hydrophilic colloidal binder under the form of very small droplets. The preferred colloidal binder is gelatin, even if some other kinds of binders can be used.
Another type of introduction of the couplers into the silver halide emulsion layer consists of the so-called "loaded-latex technique". A detailed description of such technique can be found in BE patents 853,512 and 869,816, in US patents 4,214,047 and 4,199,363 and in EP patent 14,921. It consists of mixing a solution of the couplers in a water-miscible organic solvent with a polymeric latex consisting of water as a continuous phase and of polymeric particles having a mean diameter ranging from 0.02 to 0.2 micrometers as a dispersed phase.
Another useful method is further the Fischer process. According to such a process, couplers having a water-soluble group, such as a carboxyl group, a hydroxy group, a sulfonic group or a sulfonamido group, can be added to the photographic layer for example by dissolving them in an alkaline water solution.
Useful methods of introduction of couplers into silver halide emulsions are described in Research Disclosure 308119, Section VII, 1989.
The layers of the photographic elements can be coated on a variety of supports, such as cellulose esters supports (e.g., cellulose triacetate supports), paper supports, polyesters film supports (e.g., polyethylene terephthalate film supports or polyethylene naphthalate film supports), and the like, as described in Research Disclosure 308119, Section XVII, 1989.
The photographic elements according to this invention, may be processed after exposure to form a visible image upon association of the silver halides with an alkaline aqueous medium in the presence of a developing agent contained in the medium or in the material, as known in the art. The aromatic primary amine color developing agent used in the photographic color developing composition can be any of known compounds of the class of p-phenylendiamine derivatives, widely employed in various color photographic process. Particularly useful color developing agents are the p-phenylendiamine derivatives, especially the N,N-dialkyl-p-phenylene diamine derivatives wherein the alkyl groups or the aromatic nucleus can be substituted or not substituted.
Examples of p-phenylene diamine developers include the salts of: N,N-diethyl-p-phenylendiamine, 2-amino-5-diethylamino-toluene, 4-amino-N-ethyl-N-(α-methanesulphonamidoethyl)-m-toluidine, 4-amino-3-methyl-N-ethyl-N-(α-hydroxyethyl)-aniline, 4-amino-3-(α-methylsulfonamidoethyl)-N,N-diethylaniline, 4-amino-N,N-diethyl-3-(N'-methyl-α-methylsulfonamido)-aniline, N-ethyl-N-methoxy-ethyl-3-methyl-p-phenylenediamine and the like, as described, for instance, in US patents No. 2,552,241; 2,556,271; 3,656,950 and 3,658,525.
Examples of commonly used developing agents of the p-phenylene diamine salt type are: 2-amino-5-diethylaminotoluene hydrochloride (generally known as CD2 and used in the developing solutions for color positive photographic material), 4-amino-N-ethyl-N-(α-methanesulfonamidoethyl)-m-toluidine sesquisulfate monohydrate (generally known as CD3 and used in the developing solution for photographic papers and color reversal materials) and 4-amino-3-methyl-N-ethyl-N-(β-hydroxy-ethyl)-aniline sulfate (generally known as CD4 and used in the developing solutions for color negative photographic materials).
Said color developing agents are generally used in a quantity from about 0.001 to about 0.1 moles per liter, preferably from about 0.0045 to about 0.04 moles per liter of photographic color developing compositions.
In the case of color photographic materials, the processing comprises at least a color developing bath and, optionally, a prehardening bath, a neutralizing bath, a first (black and white) developing bath, etc. These baths are well known in the art and are described for instance in Research Disclosure 17643, 1978, and in Research Disclosure 308119, Sections XIX and XX, 1989.
After color development, the image-wise developed metallic silver and the remaining silver salts generally must be removed from the photographic element. This is performed in separate bleaching and fixing baths or in a single bath, called blix, which bleaches and fixes the image in a single step. The bleaching bath is a water solution having a pH equal to 5.60 and containing an oxidizing agent, normally a complex salt of an alkali metal or of ammonium and of trivalent iron with an organic acid, e.g., EDTA.Fe.NH₄, wherein EDTA is the ethylenediaminotetracetic acid, or PDTA.Fe.NH₄, wherein PDTA is the propylene-diaminotetraacetic acid. While processing, this bath is continuously aired to oxidize the divalent iron which forms while bleaching the silver image and regenerated, as known in the art, to maintain the bleach effectiveness. The bad working of these operations may cause the drawback of the loss of cyan density of the dyes.
In addition to the above mentioned oxidizing agents, the blix bath can contain known fixing agents, such as for example ammonium or alkali metal thiosulfates. Both bleaching and fixing baths can contain other additives, e.g., polyalkyleneoxide compounds, as described for example in GB patent 933,008 in order to increase the effectiveness of the bath, or thioether compounds known as bleach accelerators.
The present invention will be illustrated with reference to the following examples, but it should be understood that these examples do not limit the present invention.

EXAMPLE 1

A multilayer silver halide color photographic film A1 was prepared by coating a cellulose triacetate support base, subbed with gelatin, with the following layers in the following order:

(1) a layer of black colloidal silver dispersed in gelatin having a silver coverage of 0.26 g/m² and a gelatin coverage of 1.33 g/m²;
(2) a layer of low sensitivity red-sensitive silver halide emulsion comprising a sulfur and gold sensitized low-sensitivity silver iodobromide emulsion (having 2.5% silver iodide moles and a mean grain size of 0.18 µm), optimally spectrally sensitized with sensitizing dyes S-1, S-2 and S-3, at a total silver coverage of 0.70 g/m² and a gelatin coverage of 1.3 g/m², containing the cyan dye-forming coupler C-1 at a coverage of 0.34 g/m², the cyan dye-forming DIR coupler C-2 at a coverage of 0.02 g/m² and the magenta colored cyan-dye forming masking coupler C3 at a coverage of 0.022 g/m², dispersed in a mixture of triphenylphosphate and butylacetanilide;
(3) a layer of medium-sensitivity red-sensitive silver halide emulsion comprising a sulfur and gold sensitized silver iodochlorobromide emulsion (having 7% silver iodide moles, 5% silver chloride moles and a mean grain size of 0.45 µm), optimally spectrally sensitized with sensitizing dyes S-1, S-2 and S-3, at a silver coverage of 0.82 g/m² and a gelatin coverage of 0.79 g/m², containing the cyan dye-forming coupler C-1 at a coverage of 0.28 g/m², the cyan dye-forming DIR coupler C-2 at a coverage of 0.019 g/m², and the magenta colored cyan dye-forming masking coupler C-3 at a coverage of 0.049 g/m², dispersed in a mixture of triphenylphosphate and butylacetanilide;
(4) a layer of high-sensitivity red-sensitive silver halide emulsion comprising a sulfur and gold sensitized silver iodobromide emulsion (having 12% silver iodide moles and a mean grain size of 1.1 µm), optimally spectrally sensitized with sensitizing dyes S-1, S-2 and S-3, at a silver coverage of 1.55 g/m², and a gelatin coverage of 1.08 g/m², containing the cyan dye- forming coupler C-1 at a coverage of 0.134 g/m², the cyan dye-forming DIR coupler C-2 at a coverage of 0.003 g/m², the cyan dye-forming coupler C-4 at a coverage of 0.051 g/m², and the magenta colored cyan dye-forming masking coupler C-3 at a coverage of 0.013 g/m², dispersed in a mixture of tricresylphosphate and butylacetanilide;
(5) an intermediate layer containing 1.13 g/m² of gelatin, 0.069 g/m² of 2,5-di-t-octylhydroquinone and 0.071 g/m² of the hardener H-1;
(6) a layer of low sensitivity green sensitive silver halide emulsion comprising a sulfur and gold sensitized silver iodobromide emulsion (having 2.5% silver iodide moles and a mean grain size of 0.18 µm), at a silver coverage of 0.64 g/m², optimally spectrally sensitized with sensitizing dyes S-4 and S-5, at a gelatin coverage of 1.2 g/m², containing the magenta dye-forming coupler M-1 at a coverage of 0.29 g/m², the magenta dye-forming DIR coupler M-2 at a coverage of 0.009 g/m², and the yellow colored magenta dye-forming couplers M-3 and M-4 at a coverage of 0.102 g/m², dispersed in tricresylphosphate;
(7) a layer of medium-sensitivity green sensitive silver halide emulsion comprising a sulfur and gold sensitized silver iodochlorobromide emulsion (having 7% silver iodide moles, 5% silver chloride moles and a mean grain size of 0.45 µm), optimally spectrally sensitized with sensitizing dyes S-4 and S-5, at a silver coverage of 0.74 g/m² and a gelatin coverage of 0.9 g/m², containing the magenta dye-forming coupler M-1 at a coverage of 0.23 g/m², the magenta dye-forming DIR coupler M-2 at a coverage of 0.024 g/m², and the yellow colored magenta dye forming couplers M-3 and M-4 at a coverage of 0.102 g/m², dispersed in tricresylphosphate;
(8) a layer of high-sensitivity red-sensitive silver halide emulsion comprising a sulfur and gold sensitized silver iodobromide emulsion (having 12% silver iodide moles and a mean grain size of 1.1 µm), optimally spectrally sensitized with sensitizing dyes S-4 and S-5, at a silver coverage of 1.5 g/m² and a gelatin coverage of 1.2 g/m², containing the magenta dye-forming coupler M-1 at a coverage of 0.106 g/m², and the yellow colored magenta dye forming couplers M-3 and M-4 at a coverage of 0.084 g/m², dispersed in tricresylphosphate;
(9) an intermediate layer containing 1.06 g/m² of gelatin;
(10) a yellow filter layer containing 1.14 g/m² of gelatin, 0.045 g/m² of silver, and 0.065 g/m² of the hardener H-1;
(11) a layer of low-sensitivity blue-sensitive silver halide emulsion comprising a blend of 63% by weight of the low-sensitivity emulsion of layer (2) and of 37% by weight of the medium-sensitivity emulsion of layer (3) at a total silver coverage of 0.57 g/m², optimally spectrally sensitized with sensitizing dye S-6, at a gelatin coverage of 1.26 g/m², containing the yellow dye forming coupler Y-1 at a coverage of 1.0 g/m² and the yellow dye forming DIR coupler Y-2 at a coverage of 0.033 g/m², dispersed in a mixture of diethyllauramide and dibutylphthalate;
(12) a layer of high-sensitivity blue sensitive silver halide emulsion comprising a sulfur and gold sensitized silver iodobromide emulsion (having 12% silver iodide moles and a mean grain size of 1.1 µm), optimally spectrally sensitized with sensitizing dye S-6, at a silver coverage of 0.84 g/m² and a gelatin coverage of 1.15 g/m², containing the yellow dye-forming coupler Y-1 at a coverage of 0.282 g/m² and the yellow dye forming DIR coupler Y-2 at a coverage of 0.03 g/m², dispersed in a mixture of diethyllauramide and dibutylphthalate;
(13) a protective layer of 1.19 g/m² of gelatin, comprising the UV absorber UV-1 at a coverage of 0.131 g/m², the UV absorber UV-2 at a coverage of 0.131 g/m², a fine grain silver bromide emulsion at a silver coverage of 0.22 g/m²; and
(14) a top coat layer of 0.86 g/m² of gelatin containing 0.190 g/m² of polymethylmethacrylate matting agent MA-1 in form of beads having an average diameter of 2.5 micrometers, and the hardener H-2 at a coverage of 0.408 g/m².

Film A2 was prepared in a similar manner as film A1, but containing in the 8th uppermost highest sensitivity green-sensitive layer 0.175 g/m² of the magenta dye-forming coupler M1 and 0.006 g/m² of the magenta dye-forming DIR coupler M2.
Film A3 was prepared in a similar manner as film A1, but replacing in the 8th uppermost highest sensitivity green-sensitive layer the magenta dye-forming coupler M1 with 0.246 g/m² of the magenta dye-forming coupler M6.
Film A4 was prepared in a similar manner as film A1, but replacing in the 8th uppermost highest sensitivity green-sensitive layer the magenta dye-forming coupler M1 with 0.266 g/m² of the magenta dye-forming coupler M5.
Samples of films A1 to A4 were exposed to a light source having a color temperature of 5,500 K (white light exposure). The exposed samples were then color processed using the KODAK FLEXICOLOR (C41) process as described in British Journal of Photography Annual , 1988, pp. 196-198, in the following sequence:

1. Color development
2. Bleach
3. Wash
4. Fix
5. Wash

For each processed sample, the characteristic curve for the green light absorption was obtained conventionally. The following Table 1 reports values of fog (Dmin), maximum optical density (Dmax), sensitivity in Log E at density of 0.2 above Dmin (Speed1), toe contrast (Gamma), values of interimage effects (IIE) and granularity (RMS) for the green-sensitive layer. The interimage effects were calculated as follows. Samples of each film were exposed to a light source having a color temperature of 5,500 K through a Kodak Wratten™ W99 filter and an optical step wedge (selective exposure). Other samples of each film were exposed as above but without any filter (white light exposure). All the exposed samples were developed as described above. Contrasts of the obtained sensitometric curves for selective exposures (gamma_s) and white light exposures (gamma_w) were measured in the low dye-density or toe region. Interimage effects (IIE) are calculated as follows:

IIE = \frac{{gamma}_{s} {- gamma}_{w}}{{gamma}_{w}} x 100

wherein the higher the numbers, the better the interimage effects. The measure of RMS granularity was made at density 1.0 above Dmin, using the ISO Standard 10505 (IOW 161): the lower the number, the lower the granularity of the image.

Table 1

Film	M _Coupler	Layer	Dmin	Dmax	Speed1	Gamma	IIE	RMS
A1	M1	8th	0.70	2.73	2.29	0.61	8	10.5
A2	M1	8th	0.68	2.82	2.29	0.68	17	9.0
A3	M6	8th	0.63	2.63	2.27	0.59	21	8.0
A4	M5	8th	0.71	2.71	2.28	0.57	30	10.1

The data show that the overall image properties (inter-image effects and speed-granularity relationship) of Films A3 and A4, containing in the uppermost highest sensitivity green-sensitive emulsion layer 4-equivalent 5-pyrazolone magenta couplers according to this invention, are better than comparison films A1 and A2 containing in all green-sensitive emulsion layers a 2-equivalent 5-pyrazolone magenta coupler.
Formulas of compounds used in this example will be presented below.

EXAMPLE 2

A multilayer color photographic film B1 was prepared similar to film A1 of Example 1, but having the following composition for the 6th, 7th and 8th green-sensitive layers:

(6) a layer of low sensitivity green sensitive silver halide emulsion comprising a sulfur and gold sensitized silver iodobromide emulsion (having 2.5% silver iodide moles and a mean grain size of 0.18 µm), optimally spectrally sensitized with sensitizing dyes S-4 and S-5, at a silver coverage of 0.55 g/m² and a gelatin coverage of 1.37 g/m², containing the magenta dye-forming coupler M-1 at a coverage of 0.283 g/m², the magenta dye-forming DIR coupler M-2 at a coverage of 0.07 g/m², and the yellow colored magenta dye-forming couplers M-3 and M-4 at a coverage of 0.1 g/m², dispersed in tricresylphosphate;
(7) a layer of medium-sensitivity green sensitive silver halide emulsion comprising a sulfur and gold sensitized silver iodochlorobromide emulsion (having 7% silver iodide moles, 5% silver chloride moles and a mean grain size of 0.45 µm), optimally spectrally sensitized with sensitizing dyes S-4 and S-5, at a silver coverage of 0.81 g/m² and a gelatin coverage of 1.05 g/m², containing the magenta dye-forming coupler M-1 at a coverage of 0.144 g/m², the magenta dye-forming DIR coupler M-2 at a coverage of 0.016 g/m², and the yellow colored magenta dye forming couplers M-3 and M-4 at a coverage of 0.113 g/m², dispersed in tricresylphosphate;
(8) a layer of high-sensitivity red-sensitive silver halide emulsion comprising a sulfur and gold sensitized silver iodobromide emulsion (having 12% silver iodide moles and a mean grain size of 1.1 µm), optimally spectrally sensitized with sensitizing dyes S-4 and S-5, at a silver coverage of 1.56 g/m² and a gelatin coverage of 1.23 g/m², containing the magenta dye-forming coupler M-1 at a coverage of 0.116 g/m², and the yellow colored magenta dye forming couplers M-3 and M-4 at a coverage of 0.051 g/m², dispersed in tricresylphosphate;

A multilayer color photographic element B2 was prepared similar to film B1, but containing in the 7th green-sensitive layer 0.218 g/m² of the magenta dye-forming coupler M1 and 0.0213 g/m² of the magenta dye-forming DIR coupler M2, and in the 8th green-sensitive layer 0.273 g/m² of the magenta dye-forming coupler M6 instead of coupler M1.
A multilayer color photographic element B3 was prepared similar to film B1, but containing in the 7th green-sensitive layer 0.303 g/m² of the magenta dye-forming coupler M6 instead of coupler M1 and magenta dye-forming DIR coupler M2 was omitted, and in the 8th green-sensitive layer 0.116 g/m² of the magenta dye-forming coupler M1.
Samples of films B1, B2 and B3 were exposed and processed as described in Example 1. For each processed sample, the characteristic curve for the green light absorption was obtained conventionally. The following Table 2 reports values of fog (Dmin), maximum optical density (Dmax), sensitivity in Log E at density of 0.2 above Dmin (Speed1), toe contrast (Gamma), and values of interimage effects (IIE) and granularity (RMS, at density 1.3 above Dmin) for the green-sensitive layers. Table 2

Film M _Coupler Layer Dmin Dmax Speed1 Gamma IIE RMS

B1 M1 8th 0.72 2.77 2.31 0.59 13 7.3

B2 M6 8th 0.67 2.68 2.29 0.60 22 6.4

B3 M1 8th 0.72 2.81 2.33 0.60 19 7.3
The data show that film B2, having the 4-equivalent 5-pyrazolone magenta coupler in the uppermost highest sensitivity green-sensitive emulsion layer, gives better interimage effects and granularity.

Claims

A silver halide photographic element comprising a support having coated thereon red-, green- and blue-sensitive silver halide emulsion layers comprising, respectively, cyan, magenta and yellow dye-forming couplers, wherein the green-sensitive layer comprises three green-sensitive layers having different sensitivity, an uppermost green-sensitive layer being more sensitive than an intermediate green-sensitive layer which is more sensitive than a lowermost green-sensitive layer, the layers arranged with the lowermost green-sensitive layer being closer to the support, the intermediate green-sensitive layer being adjacent said lowermost green-sensitive layer and the uppermost green-sensitive layer being above the intermediate green-sensitive layer, characterized in that the uppermost green-sensitive emulsion layer comprises 4-equivalent 5-pyrazolone magenta dye-forming couplers, and the intermediate and the lowermost green-sensitive emulsion layers comprise 2-equivalent 4-arylthio-5-pyrazolone magenta dye-forming couplers.
A photographic element as claimed in claim 1, wherein the 2-equivalent 4-arylthio-5-pyrazolone magenta coupler is represented by the formula
wherein
a represents an integer from 0 to 3,

b represents an integer from 0 to 2,

R₁ and R₂ are each individually hydrogen, alkyl, alkoxy, halogen, aryl, aryloxy, acylamino, sulfonamido, sulfamoyl, carbamoyl, arylsulfonyl, aryloxycarbonyl, alkoxycarbonyl, alkoxysulfonyl, aryloxysulfonyl, alkylureido, arylureido, nitro, cyano, hydroxyl or carboxy group,

R₃ is halogen atom, alkyl group or aryl group,

X is a direct link or a linking group,

Ball is a ballasting group which renders a group to which is attached non-diffusible in photographic coatings, and

the sum of the sigma values of R₁, R₃ and X-Ball is less than 1.3.
A photographic element as claimed in claim 2, wherein Ball comprises a hydrophobic group of at least 8 carbon atoms.
A photographic element as claimed in claim 2, wherein R₁ is chlorine, a represents 3 and chlorine atoms are in the positions 2, 4 and 6 with respect to the carbon atom attached to the nitrogen atom.
A photographic element as claimed in claim 2, wherein R₃ is chlorine.
A photographic element as claimed in claim 1, wherein the 4-equivalent 5-pyrazolone magenta dye-forming coupler is represented by the formula
wherein
a represents an integer from 0 to 3,

R₁ is hydrogen, alkyl, alkoxy, halogen, aryl, aryloxy, acylamino, sulfonamido, sulfamoyl, carbamoyl, arylsulfonyl, aryloxycarbonyl, alkoxycarbonyl, alkoxysulfonyl, aryloxysulfonyl, alkylureido, arylureido, nitro, cyano, hydroxyl or carboxy group,

R₃ is halogen atom, alkyl group or aryl group,

X is a direct link or a linking group,

Ball is a ballasting group which renders a group to which is attached non-diffusible in photographic coatings, and

n represents 0 or 1.
A photographic element as claimed in claim 6, wherein R₁ is chlorine, a represents 3 and chlorine atoms are in the positions 2, 4 and 6 with respect to the carbon atom attached to the nitrogen atom.
A photographic element as claimed in claim 1, wherein the 4-equivalent 5-pyrazolone magenta dye-forming coupler is used in the uppermost highest sensitivity green-sensitive emulsion layer in an amount ranging from 0.01 to 0.5 mol per mol of silver halide.
A photographic element as claimed in claim 1, which consists of a support comprising in the order an antihalation layer, three layers of silver halide emulsions sensitized to the red light of increasing sensitivity from the support and containing cyan dye-forming couplers, three layers of silver halide emulsions sensitized to the green light of increasing sensitivity from the support and containing magenta dye-forming couplers, a yellow dye filter layer, and two layers of silver halide emulsions sensitized to the blue light of increasing sensitivity from the support and containing yellow dye-forming couplers.