US3816121A - Direct positive photographic material containing a color coupler under one micron in size and fogged silver halide grains with substantially no internal sensitivity having absorbed on the surface a desensitizing dye containing a solubilizing group - Google Patents

Abstract

A color photographic material having at least one silver halide photographic emulsion layer containing chemically fogged direct positive silver halide grains, said silver halide photographic emulsion layer simultaneously satisfying the following criteria: 1. SAID SILVER HALIDE PHOTOGRAPHIC EMULSION HAVING SUBSTANTIALLY NO FREE ELECTRON TRAP IN SAID SILVER HALIDE GRAINS; 2. SAID SILVER HALIDE PHOTOGRAPHIC EMULSION HAVING ADSORBED ON THE SURFACE OF SAID SILVER HALIDE GRAINS AN ELECTRON ACCEPTOR HAVING A WATER-SOLUBLE ANIONIC GROUP OR AN ANIONIC GROUP FORMING A BETAINE STRUCTURE; 3. SAID SILVER HALIDE EMULSION CONTAINING DROPLETS OF AN OILSOLUBLE COLOR COUPLER DISPERSED THEREIN, THE MEAN DROPLETS SIZE IN DIAMETER OF SAID COUPLER BEING SMALLER THAN ABOUT 1 MICRON; AND 4. SAID SILVER HALIDE EMULSION LAYER FORMING A COLOR IMAGE ON DEVELOPMENT WITH A COLOR DEVELOPING SOLUTION CONTAINING A PHENYLENEDIAMINE OR A DERIVATIVE THEREOF AS THE COLOR DEVELOPING AGENT IS DISCLOSED.

Description

United States Patent [191 Shiba et al.

1 June 11, 1974 1 DIRECT POSITIVE PHOTOGRAPHIC MATERIAL CONTAINING A COLOR COUPLER UNDER ONE MICRON IN SIZE AND FOGGED SILVER HALIDE GRAINS WITH SUBSTANTIALLY NO INTERNAL SENSITIVITY HAVING ABSORBED ON THE SURFACE A DESENSITIZING DYE CONTAINING A SOLUBILIZING GROUP [75] Inventors: Keisuke Shiba; Hiroyuki Amano;

Hirozo Ueda; Akira Sato, all of Kanagawa, Japan [73] Assignee: Fuji Photo Film Co., Ltd.,

Kanagawa, Japan 22 Filed: Sept. 5, 1972 211 Appl. No.: 286,395

[30] Foreign Application Priority Data Sept, 4, 1971 Japan 46-68250 [52] US. Cl 96/97, 96/101, 96/107,

' 96/108, 96/94 R, 96/74, 96/100 [51] Int. Cl. G03c 1/10, G03c l/36, G03c 1/28 [58] Field of Search 96/101, 100, 97, 107, 108,

Mee et a1 3,501,305 3/1970 lllingsworth 96/101 3,501,306 3/1970 lllingsworth 96/ l 01 3,687,674 8/1972 Sato et a1 96/101 [57] ABSTRACT A color photographic material having at least one silver halide photographic emulsion layer containing chemically fogged direct positive silver halide grains, said silver halide photographic emulsion layer simultaneously satisfying the following criteria:

1. said silver halide photographic emulsion having substantially no free electron trap in said silver halide grains;

2. said silver halide photographic emulsion having adsorbed on the surface of said silver halide grains an electron acceptor having a water-soluble anionic group or an anionic group forming a betaine structure;

3. said silver halide emulsion containing droplets of an oil-soluble color coupler dispersed therein, the mean droplets size in diameter of said coupler being smaller than about 1 micron; and

4. said silver halide emulsion layer forming a color image on development with a color developing solution containing a phenylenediamine or a derivative thereof as the color developing agent is disclosed.

17 Claims, 15 Drawing Figures PATENTEDM I 1 m4 smellzl SHEET HP 2 FIG. 2

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DIRECT POSITIVE PHOTOGRAPHIC MATERIAL CONTAINING A COLOR COUPLER UNDER ONE MICRON IN SIZE AND F OGGED SILVER HALIDE GRAINS WITH SUBSTANTIALLY NO INTERNAL SENSITIVITY HAVING ABSORBED ON THE SURFACE A DESENSITIZING DYE CONTAINING A SOLUBILIZING GROUP BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color photographic material for obtaining a color positive image directly by using a color developing solution containing a conventionally used phenylenediamine derivative. More particularly, the invention relates to a direct positive type color photographic material having improved sensitivity-, clearness of the highlight portions, exposure latitude, and color reproducibility as well as an excellent stability.

2. Description of the Prior Art With the coming of the information era, the development of information recording materials having a high density recording capacity and capable of recording by a faster and easier process has become necessary. One of such recording materials is a silver halide photographic light-sensitive material. Silver halide photographic light-sensitive materials ordinarily used are developed in various manners according to their uses and thus it has been also required to simplify the developing procedure.

In order to increase the density and capacity for recording, various attempts have been proposed. For instance, various attempts have been proposed such that the granularity is made fine, the sharpness is increased, the light-sensitive wave length region is extended to the wave length regions sensitive to electron beams, gamma-rays, X-rays, ultraviolet rays, visible rays, and near infrared rays, a multilayer type sensitive material is em ployed, the absorption wave length region of the imageforming materials obtained is changed, that is, the gray image formed by the reduced silver and the colored image such as the yellow image, the magenta image, the cyan image, the red image, the blue image, etc., obtained by color development are utilized, and the like.

In the case of a silver halide photographic lightsensitive material ordinarily employed, a negative image of an original is obtained by a series of developing procedures including one developing process. Accordingly, in order to obtain a positive image of an original using such an ordinary silver halide photographic light-sensitive material, it is required that the negative image obtained by conducting the above-described series of developing procedures is exposed again for printing and further another series of developing procea washing, a bleaching, a washing, a fixing, a washing, and a stabilization. In general, such a system is quite troublesome and requires a considerable period of time. Therefore, it is frequently advantageous to record or reproduce a positive image directly as the positive image.

The direct positive color photographic material of this invention can provide a color positive image directly from an original by processing it using color developing procedures ordinarily used for developing color photographic negative materials and color photographic positive materials and in particular color photographic papers. By using the direct positive color photographic material of this invention, a color positive image can be obtained from an original rapidly, easily and economically by using conventionally employed color developing procedures. However, such an ordinary direct positive color photographic material has been found at present to have various defects. Furthermore, as compared with direct positive black and white photographic materials, the production of the direct positive color photographic materials encounters specific technical difficulties. They are as follows:

The first difficulty is that the sensitivity is low, in particular, the spectral sensitivity in a specific wave length region is low. The second difficulty is that the clearness at the highlight portions is insufficient. The third difficulty is that in the process of producing photographic sensitive materials, the flowable emulsions are poor in stability and also the maintenance of uniform photographic properties is difficult. The fourth difficulty is that the direct positive color photographic materials are poor in stability. The fifth difficulty is that a sufficient gradation is difficult to obtain.

An object of this invention is, therefore, to improve these defects.

SUMMARY OF THE INVENTION The inventors have discovered that the aforesaid difficulties can be overcome by using a direct positive silver halide photographic emulsion satisfying the following four criteria: that is,

l. a silver halide photographic emulsion which has substantially no free electron trap in the silver halide grains,

2. a silver halide emulsion which contains adsorbed on the surface of the silver halide grains an electron acceptor having a water-soluble anionic group or such an anionic group that can provide a betaine structure in the molecule, in particular at least one sulfo group, carboxyl group, or phosphoric acid group,

3. a silver halide emulsion which contains a hydrophobic color coupler dispersed in a hydrophilic colloid or water, in particular an oil-soluble color coupler in such a condition that the mean particle size thereof is less than about one micron,

4. a silver halide emulsion which can provide a colored dye image by using a color developing solution containing a phenylenediamine derivative (this term includes those compounds which are equivalent to the derivative) as the color developing agent.

Thus, a color photographic material meeting the objects of this invention is provided according to this invention by applying to an appropriate support at least one layer of the fogged direct positive silver halide photographic emulsion satisfying the aforesaid four criteria.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS FIGS. 1, 2, 3,and 4 are characteristic curves of the silver halide photographic emulsion of this invention and silver halide photographic emulsions prepared for the purposes of comparison.

1 FIGS. 5 to 14 are spectrophotographs obtained using the silver halide photographic emulsions of this inventron.

FIG. 15 is a spectral transmittance curve of Filter K-31 and Wratten 47B Filter. 1

DETAILED DESCRIPTION OF THE INVENTION The inventors will first assert that the above described constitution and the advantages of this invention have never been anticipated from the combinations of the individually conventional techniques in the field and also believe that this will be fully understood from the detailed explanation of this invention and advantages obtained as set forth below in this specification.

The first feature of this invention is in the photosensitive characteristics of the silver halide grains contained in the silver halide photographic emulsion. That is to say, the surface of the silver halide grains in the direct positive type silver halide photographic emulsion has been chemically fogged and the fogged silver halide grains absorb exposed radiations, preferably visible rays, ultraviolet rays, electron beams, gamma-rays, etc., to generate free electrons in the grains, while forming positive holes at the surface of or inside of the silver halide grains. In this case, if electron trap are present in the silver halide grains preferably at the central portion of each silver halide grain, the free electrons are caught by the electron trap. Furthermore, if an electron acceptor or an electron trap site is present at the surface of the silver halide grains, the free electron is caught by it. On the other hand, a portion of the positive holes are recombined with the free electron or caught by the physical defect of the silver halide grains but the greater portion of the positive holes shift to the surface of the silver halide grains, where they are caused to react with the fogging specks to lose developing activity. Thereafter, by subjecting the silver halide emulsion layer to the subsequent developing processing, developing centers giving a positive image directly can be obtained in conformity with the exposed energy or image. The silver halide photographic emulsion used in this invention comprises silver halide particles having substantially no free electron trap in the particles and a hydrophilic colloid.

Now, a direct positive photographic emulsion having electron trap is well known as the internal sensitive emulsion, the core-outershell type emulsion and so on which are disclosed in Japanese Patent Publication No. 4125/68; Japanese Patent Publication No. 29,405l68; the specifications of US. Pat. Nos. 2,401,051; 2,717,833; 2,976,149; and 3,023,102; the specifications of British Pat. Nos. 707,704; 1,097,999; and 690,997; the specifications of French Pat. Nos. 1,520,822; 1,520,824; 1,520,817; and 1,523,626; and the specifications 'of Belgian Pat. Nos. 713,272; 721,567; and 681,768.

The direct positive photographic emulsion of the type having electron trap has a comparatively high possibility that the positive holes are recombined with electrons generated in the silver halide grains and since the positive holes are reluctant to react effectively with the fogging specks, such a direct positive emulsion has a characteristic that the provision of high sensitivity to the emulsion is difficult. Furthermore, the important matter in such a direct positive emulsion is that the free electron trap in the silver halide grains become a latent image and if they are positioned comparatively at a surface portion, they act as developing centers and they reduce the highlight clearness. Moreover, they give a negative image in the highlight domain to greatly narrow the exposure latitude. This disadvantage appears markedly in the case of color development as compared with the case of the infectious development used for developing lithographic light-sensitive materials and in the case of the Metol-hydroquinone development or the Metol-pyrazolidone development used for developing ordinary black and white light-sensitive materials.

On the other hand, a photographic emulsion having substantially no free electron trap in the silver halide grains does not give a sufficient direct positive image by itself. Therefore, in order to improve the properties of such a photographic emulsion, it has been proposed to adsorb an electron acceptor or a material having a similar function to any electron acceptor on the surface of silver halide grains.

The inventors have discovered that whether a direct positive type silver halide emulsion is a photographic emulsion of the type having substantially no free electron trap in the silver halide grains as in this invention or not can be easily and clearly determined by one skilled in the art according to the following method: That is to say, a fogged direct positive silver halide photographic emulsion is coated on a support such as a glass sheet, a polyethylene terephthalate film base or a cellulose triacetate film base in a dry thickness of less than about 5 microns. In this case it is preferable that the amount of silver halide coated be so selected that the maximum optical density obtained due to development becomes 1.0 to 1.5. The sample thus prepared is exposed behind an optical wedge to a sufficient amount of blue light or white light, developed for 2 minutes at 20C. using a Developer D-72 made by the Eastman Kodak Company, having the following composition:

Composition of Developer D-72 Water 500 cc Metal 3 g Anhydrous Sodium Sulfite 45 g Hydroquinone 12 g Anhydrous Sodium Carbonate 67.5 g Potassium Bromide 2 g Water to make L000 cc (This developer is used by diluting with an equal volume of water) The developed sample was then fixed, whereby a characteristic curve of a direct positive type is obtained. In this case, the blue light used in the above exposure is obtained using a tungsten light passed through a Filter K-31 made by the Fuji Photo Film Co., or a Wratten 478 Filter. In place of the Developer D-72, a Developer D-19 may also be employed, which has the following composition:

Composition of Developer DI) Water 500 cc Metal 2 g Anhydrous Sodium Sulfite 90 g Hydroquinone 8 g Sodium Carbonate Monohydrate 52.5 g Potassium Bromide g Water to make 1,000 cc On the other hand, a sample prepared in the same manner as described above is degassed for longer than 17 hours at normal temperature under a reduced pressure of mm/I-Ig and subjected to sensitometry using the same blue light or a white light as described above under reduced pressure to provide a characteristic curve. Usually, the characteristic curve obtained by conducting sensitometry in air is compared with the characteristic curve obtained by conducting the sensitometry in vacuo after subjecting the sample to a degassing treatment. In this case, when the minimum optical density value D,,,,,,. (the clearness of the highlight portions) of the latter is higher than the optical density corresponding to 30 percent of the maximum optical density value D (fog density in the unexposed state) of the former or alternatively the sensitivity of the latter at a point of one-half of the maximum optical density thereof is lower than 65 percent of the sensitivity of the former at the point of one-half of the maximum optical density thereof, the silver halide photographic emulsion of the sample is defined to have substantially no electron trap in the silver halide particles as in this invention. This definition can be applied not only the samples prepared by the preparation method as described above but also to direct positive light-sensitive materials. Even though the degassing treatment as described above is conducted in a vacuum condition higher than 10" mm/Hg, the above defined value is easily obtained and thus even in such case, the results meeting the definition for the photographic emulsion of this invention are frequently obtained.

For providing the electron trap in the inside of the silver halide grains, it is known to apply a chemical sensitization or apply iodine ion, an ion of a metal belonging to Group II of the periodic table such as a Zn ion or a Sr ion, an ion of a metal of Group VIII, such as an Ir ion, a Rh ion, a Ru ion, or a Pt ion, or an ion ofa metal of Group V, such as a Bi ion or an As ion. Example of materials which can be used to provide the above metal ions include zinc chloride, zinc nitrate, strontium chloride, strontium sulfate, hexahalogeno iridate, trihalogeno iridate, hexahalogeno rhodate, hexahalogeno ruthenate, hexahalogeno platinate and the like. However, even if such a compound as described above is incorporated in a silver halide photographic emulsion, it will not be detennined that there are electron trap in the silver halide grains from this fact alone. On the other hand, the method of using the degassing effect discovered by the inventors of the present invention is based on the fact that the efficiency of the free electrons which can be accepted on the surface of the silver halide grains or accepted outside the grains are extremely reduced and it is believed to be a very clear, excellent, and reasonable method. This method will be further explained more specifically in Experiment 1.

A second feature of this-invention is in the point that an electron acceptor having at least one anionic radical, which is a water-soluble radical such as a sulfo radical, a carboxyl radical or a phosphoric acid radical, and can form a betaine structure in the molecule with a core atom having a positive charge formed by the localized presence of IT-ElCCU'OIlS or by ionization is adsorbed on the surface of the silver halide grains. F urthermore, the silver halide photographic emulsion of this invention contains the electron acceptor and a color coupler together.

It is known to introduce a sulfo radical, a carboxyl radical, a phosphoric acid radical, an amino radical, or a radical derived from each of the aforesaid radicals to a sensitizing dye for preventing the reduction of spectral sensitivity caused by the presence of the color coupler in an ordinary negative type silver halide emulsion. However, such an effect is not known with respect to an electron acceptor.

In the electron acceptor used in this invention, by introducing at least one of the anionic radicals as defined above into the electron acceptor, not only is the reduction of the spectral sensitivity prevented but also the desensitization of the silver halide grains by the adsorption of the color coupler and the reduction of the clearness of the highlight portions are also prevented and further the intrinsic sensitivity of the silver halide grains is also increased. Thus, it has been astonishingly discovered that when the electron acceptor asdefined in this invention is present together with a color coupler, excellent results meeting the objects of this invention are obtained.

When the electron acceptor in this invention is used together with a soluble bromine ion, iodine ion, or a mixture thereof, the adsorption of the electron acceptor is further improved, the desensitization by a color coupler is prevented, and in particular the spectral sensitivity is also increased, which give advantageous results to the production of the color photographic materials of this invention. The electron acceptor used in this invention includes many of so-called desensitizers or deor non-sensitizing dyes. In other words, the electron acceptor may be a compound capable of catching the free electrons of silver halide grains and having the lowest vacant electron energy level lower than the electron conduction band of the grains. More preferably, the electron acceptor in this invention is a compound having a maximum occupied electron energy level lower than the valence electron band of the silver halide grains. It is known that those electron energy levels correspond linearly to the cathodic polarographic halfwave potential (E or the anodic polarographic halfwave potential (E The electron acceptor of this invention is preferably a compound having an E value equal to or more positive than l.0 volt and an E value equal to or more positive than 0.7 volt. An E value equal to or more positive than l.0 volt means that the electron acceptor has an electron affinity capable of sufficiently catching the free electrons. Also, an E value equal to or more positive than 0.7 volt means that the electron acceptor has an ionization potential capable of not too effectively catching the positive holes formed in the silver halide grains.

The E value is determined by measuring in an acetonitrile solution containing tetra-n-propylammonium perchlorate as a supporting electrolyte at 25C. using a mercury dropping electrode and further a saturated calomel electrode (SCE) as a reference electrode. Furthermore, the value is measured in an acetonitrile solution of l X 10" mole to l X 10 mole per liter.

The E value is determined by using sodium perchlorate as a supporting electrolyte, a rotary platinum electrode as an anode, and a saturated calomel electrode as a reference electrode (see, the specification of German OLS No. 2,010,762).

The third feature of this invention is in the point that the silver halide emulsion contains an oil-soluble color coupler in a dispersed state of fine particles having a mean particle size of less than about 1.0 micron.

Various methods are known for dispersing color couplers in hydrophilic colloids. By one of those known method, a sulfo radical, a carboxyl radical, a hydroxyl radical, or an amino radical is introduced into the molecule of a color coupler, the color coupler is dispersed in a hydrophilic colloid as an aqueous solution or an alkaline solution thereof, and the dispersion is incorporated in a silver halide emulsion in micelle form. There is also provided a method of solubilizing the color coupler with the aid of a surface active agent and incorporating the coupler in a silver halide emulsion.

Also, using another method, a color coupler which is soluble in an oil such as fat but substantially insoluble in water (for instance, having a solubility in water of less than 1 percent by weight) is dissolved at least partially in a high boiling plasticizer such as tricresyl phosphate, polyethyl acrylate, polybutyl methacrylate, di-

butyl phthalate, and a biphenyl ether derivative or an oil such as a fat or an oil, it is then dispersed in an emulsion as fine particles with the aid of a surface active agent. Also, where the oil-soluble color coupler itself is oily or in a liquid state at high temperatures, a method is known in which the coupler is directly dispersed in an emulsion with the aid of a surface active agent. Furthermore, in the case of employing a solid color coupler, the coupler is mechanically ground into fine particles and they are dispersed in an emulsion. Still further, a color coupler can be dispersed in an emulsion together with a hydrophilic colloid by utilizing the intramolecular co-action between the coupler and the hydrophilic colloid.

Many color couplers used for color photographic materials are known. A color coupler capable of forming a dye with a color developing solution containing a penylenediamine derivative as a color developing agent in the presence of silver halide grains which have become developable by exposure or chemical fogging can be said to have a certain reducing power, principally, to the oxidation product of the color developing agent. When a color coupler is adsorbed on silver halide grains, it frequently forms positive hole traps in the silver halide grains. In particular, a magenta couple r, for instance, a coupler having a -pyrazolone nucleus, a coupler having an indazolone nucleus, and a coupler having a cyanoacetophenone nucleus has a strong tendency for this. Accordingly, when such a color coupler is incorporated in a direct positive silver halide emulsion, it tends to give adverse effects such as a reduction in sensitivity, a reduction in the cleamess of the highlight portions, and a deterioration of the stability. Thus, when such a color coupler is used for color photographic materials, a specific technique is required.

The inventors have discovered that the above disadvantages can be removed by pre-dispersing the oilsoluble color coupler which is substantially insoluble, in water in a sufiiciently fine state corresponding to the size of the silver halide grains, e.g., as fine particles of less than 1 micron and adding the dispersion to a silver halide emulsion. This remarkable phenomenon is not presently known by persons skilled in the art and the surprising effects have not been reported in any of the literature.

On the other hand, even if the above process is applied to a conventional negative type color photographic materials, no such effect as described above is obtained. It is particularly important to disperse an oilsoluble color coupler discretely as sufficiently small fine particles and if the same oil-soluble color coupler is dispersed as coarse particles or the solubility thereof in water is microscopically increased or the color coupler is brought into contact with the silver halide particles as the results of using a surface active agent or a solvent aid in a wrong manner, the sensitivity of the silver halide emulsion is reduced and further the clearness of the highlight portions is also reduced. This will be more practically explained in Experiment 2.

The fourth feature of this invention is in the point that a direct positive color photographic image having good cleamess of the highlight portions, a wide exposure latitude, and sufficient gradation can be obtained by the developing process in a' color developing solution using a conventional phenylene-diamine type color developing agent.

A conventionally employed color developing solution has generally the property of developing even an internal latent image and also-a physical developing property. Therefore, in the case of developing in such a conventional color developing solution, the cleamess of highlight portions is greatly reduced and thus the highlight portion is apt to be developed to form a negative image again in comparison with the case of using a conventional black and white developing solution. Accordingly, a specific improvement has been required in the color developing process. However, as described above, it is extremely economical from the standpoint of simplification in a mono-bath process to employ the conventional color developing process. Thus, the aforesaid difficulties in the case of using the conventional color developing process have been overcome by preparing the direct positive type silver halide emulsion, selecting specifically the electron acceptor used for preparing the emulsion, and selecting the color coupler to be incorporated therein and the dispersing method for dispersing the coupler according to the present invention.

The fifth feature of the present invention is in the point that the objects of this invention can be first attained by combining the above-described factors of this invention. This will be readily understood from the following description in this specification.

The silver halide photographic emulsion used in this invention is one which has previously been fogged chemically. The fogged nuclei are provided by the addition of an inorganic reducing compound such as stannous chloride or a hydrated borate or an organic reducing compound such as a hydrazine derivative, formalin, thiourea dioxide, a polyamine compound, an amine borane, and methyl dichlorosilane. Also, a combination of a reducing agent and metal ions more noble than silver ions or a combination of a reducing agent and hydride ions can be used for the chemical foggingof silver halide photographic emulsion as described in the specifications of, e.g., US. Pat. Nos. 2,497,875; 2,588,982;

3,023,102; and 3,367,778; British Pat. Nos. 707,704; 723,019; 821,251; and 1,097,999; French Pat. Nos. 1,513,840; 1,518,095; 739,755; 1,498,213; 1,518,094; 1,520,822; and 1,520,824; Belgian Pat. Nos. 708,563 and 720,660; and Japanese Patent Publication No. 13488/1968.

In the silver halide photographic emulsions used in this invention, gelatin is ordinarily used as the protective colloid but the use of inactive gelatin is particularly advantageous. However, an inactive gelatin derivative or a hydrophilic synthetic polymer such as polyvinyl acrylate, polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl alginate may also be used in place of the gelatm.

The silver halide photographic emulsion of this invention may contain a mercapto compound, a thion compound, or a tetraazaindene derivative as a stablizer for the fogged nuclei; a stilbene compound or a triazine compound as a modifier for clearness;.a brightening agent; a ultraviolet adsorbent; a fading preventing agent for colored images; chrome alum, a 2,4-dichloros-triazine compound, an aziridine compound; or an epoxy compound as a hardening agent; an anionic surface active agent or an amphoteric surface active agent as a dispersing and spreading agent; a lubricating agent; and a plasticizer.

Now, the electron acceptors used in this invention will be illustrated below although this invention is not to be interpreted as being limited to the specifically illustrated compounds.

General Formula I:

wherein B represents an atomic group necessary for forming a heterocyclic ring, which is usually selected from the heterocyclic ring nuclei used in cyanine dyes such as 2-quinoline benzoxazole, quinoxaline, indolenine nuclei; R, represents an alkyl group (including substituted alkyl groups), an unsaturated aliphatic group or an aryl group, the alkyl groups being preferably a lower alkyl group having 1 to 6 carbon atoms such as methyl, ethyl, propyl, methylvinyl, acetoxyethyl, sulfopropyl, carboxymethyl, carboxyethyl and the like; A, represents a phenyl group having at least one nitro group, a naphthyl or a heterocyclic ring nucleus such as indole and pyrazol nuclei and the like; m and n each represents an integer of l or 2, the compound forming a betaine structure when m is l; and X represents an anion usually used in cyanine dyes; the R,, B or A, containing at least one of a sulfo group, a carboxyl group or a phosphoric acid group.

General Formula ll:

wherein Z, represents an oxygen atom, a Nl-l group, or a CH== group; Z represents an atomic group necessary for forming a cycloheptatriene ring; A

represents a hydrogen atom, an oxygen atom (=0), or a halogen atom; L, and L each represents a methine group (including a substituted methine group such as those substituted by methyl, phenyl, cyano or the like); Z represents an atomic group necessary for forming a heterocyclic ring, particularly a heterocyclic nucleus usually used in cyanine dyes; X, n, and m have the same meaning as described in General Formula I; and R represents an alkyl group (including a substituted alkyl group (aralkyl group)) having at least one sulfo group, a carboxyl group, or a phosphoric acid group or an unsaturated aliphatic group, such as methyl, ethyl, propyl, carboxyethyl, carboxybutyl, sulfopropyl, sulfoisobutyl and the like.

GeneraLFormula Ill:

wherein 2, represents an indole nucleus, a carbazole nucleus, or a phenothiazine nucleus; Z has the same meaning as described for Z in the General Formula ll; R, represents an alkyl group (including a substituted alkyl group), an unsaturated aliphatic group, or an aryl group such as methyl, ethyl, propyl, carboxyethyl, sulfobutyl, phosphopropyl, methylvinyl, p-sulfobenzyl and the like; the alkyl group being preferably a lower alkyl group having 1 to 6 carbon atoms; the Z Z, or R wherein Z and Z, each represents an atomic group necessary for forming a S-membered or 6-membered heterocyclic nucleus, at least one of Z, and Z representing an atomic group necessary for forming a S-membered or 6-membered heterocyclic nucleus having an electron accepting property or a desensitizing action, in particular 2,, or Z, representing indole, nitrosubstituted indolenine, imidazoquinoxaline, nitrosubstituted benzothiazole, pyrrolopyridine, or nitrosubstituted benzoxazole; R and R have the same meaning as described for R, in the General Formula 1; at least one of the R and R containing a sulfo group, a carboxyl group, or a phosphoric acid group; q represents an integer of l, 2, or 3; r and s each represents an integer of l or 2; L,, L and L each represents a methine group (including a substituted methine group); and X and m have the same meaning as described in the General Formula 1.

The examples of the aforesaid heterocyclic nuclei usually used in cyanine dyes include an oxazole nucleus, a benzoxazole nucleus, a naphthoxazole nucleus, a thiazole nucleus, a benzothiazole nucleus, a naphthothiazole nucleus, a selenazole nucleus, a benzoselennucleus, and a pyrrolopyride nucleus.

Also, the examples of the anions usually used in cyanine dyes include halogen ions, chlorate ions, thiocyanate ions, methyl sulfate ions, ethyl sulfate ions, sulfonate ions, and p-toluenesulfonate ions.

Suitable specific examples of the compounds used as the electron acceptors in this invention are illustrated below:

( B940 0 OH The mean grain size used in this invention can be easily obtained from the analysis of the wave length dependence of the light scattering of a coupler-containing emulsion. This method is fundamentally based upon the principle described in the report of R. J. Gledhill et 5 al., Journal of Optical Society of America, Vol. 53, 239-246( 1963).

Suitable specific examples of the compounds used as l (Q s u color couplers in this invention are illustrated below but the invention is not in any way intended to be inter- (C4) preted as limited to these examples. NH-oo nao-o-o 0-CH1-C ONH- 0-1 15 :11, (El

( 111-0 (t)Cs n C2 s l a u O-GHzC ONH (t) s n 20 Amthat m W 05H OCH; (C 5) 0,11, COCHz (0051111 -0-CHCO-IIIH COOCHHN 25 (00 m -CO- Q-o oo HT-c O-NH 0 CH;

(')CH; CH-CONH OCOCH:

{CT-ET 01 m (3H3 II;C-ZC0-(|1IICO-NH (0051111 l OCH;

s 7.. t (a) cumQ-oomo ONE H" Q-coom-orq (C-IO) E (IJZH5 \NH Q-O-CH-GONH (C-ll) (UCsHn (U iHn 0 01-120 O-NH oomronocoom 11 fi-CONECHKJIL- CzHs Q-NHCO 6H-O-Q-(t) CBHII 01- NHCOCH:O(1:) 011111 H5O (fl sHn wCONHC H (Comparison Color'Coupler (0)) These color couplers above give colored images with a color developing agent comprising pphenylenediamine or a derivative thereof. It is preferable to use those color couplers having at the active methylene position a substituent group capable of conducting splitting development imagewise at the step of color development, such as a halogen atom, an aryldiazo group, an arylthio group, an aryloxy group, or a carboxyl group (the compounds described in, e.g., the specifications of US. Pat. Nos. 3,311,476; 3,408,194; and 3,447,928).

The color developing solution used in this invention contains as a color developing agent phenylenediamine or a derivative thereof and a small amount of a sulfite and having a pH in an alkaline region or preferably a pH of higher than 9.8. Suitable examples of such color developing agents are p-amino-N-ethyl-N-B- (methanesulfoamidoethyl -m-toluidine sesquisulfate monohydrate, diethylamino-p-phenylenediamine sesquisulfite, p-amino-N,N-diethyl-m-toluidine hydrochloride, p-amino-N-ethyl-N-B-hydroxyethylphenylene sesquisulfate monohydrate, etc.

In the present invention any known color developing solutions for color photographic negative materials, cine-color photographic negative materials, cine-color photographic positive materials, color photographic papers, and instant color photographic materials can be employed. For instance, such color developing processes which may be employed in this invention are described in the specifications of Japanese Patent Publication No. 35,749/1970; Japanese Patent Application No. 67,798/ 1969, and Japanese Patent Application No. 13,313/ 1971 as well as described in H. Gordon; The British Journal of Photography; pages 558-, published on Nov. 15, 1954; ibid.; pages 440-, published on Sept. 9, 1955, ibid.; pages 2-, published on Jan. 6, 1956, S. Horwitz; ibid.; pages 212-, published on Apr. 22, 1960; E. Gehret, ibid., pages 122-, published on Mar. 4, 1960; ibid., pages 396-, published onMay 7, 1965; and

A .1. Meech, ibid., pages 182-, published onApr. 3, 1959.

' Suitable silver halide photographic emulsions which can be used in this invention are a pure silver bromide emulsion, a silver iodobromide emulsion (including silver bromide grains having iodine ions adsorbed on the surface), a silver chlorobromide emulsion, a silver chloroiodobromide emulsion, and mixtures thereof. The grain size of the silver halide in the photographic emulsion ranges from 0.04 micron to 2 microns, in particular 0. 15-07 micron. A pure silver chloride emulsion or a silver halide emulsion containing silver halide grains coarser than 1 micron is undesirable since in this case the internal sensitivity of the silver halide grains becomes too high. Furthermore, bromine ions or iodine ions can be adsorbed on the surface of the silver halide grains or further the ions having an electron-accepting property or a desensitizing action, such as the ions of a metal of Group lb, Group IVb or Group VIII, e. g., cupric chloride, lead nitrate, lead bromide, hexachloro iridate, hexachloro rhodate, ferricyanate salt can be adsorbed on the surface of the silver halide grains.

The electron acceptorin this invention can be used alone as well as used in combination with other dyes in particular as an electron acceptor. It is preferable to use the electron acceptor in an amount of -.from 1 X 10 mole to5 X 10. mole, preferably from 1 X 10' to 5 X 10 mole per mole of the silver halide in the photographic emulsion. Still further, a photographic dye such as an antihalation dye, an dye which prevents light scattering, or a dye for filter layer can also be used. In particular, a water-soluble dye such as a triphenylmethane dye such as those disclosed in F r'ench Patent No. 2,012,545; British Pat. Nos. 1,027,747; 1,025,567; US. Pat. Nos. 3,382,074 and 3,406,069, a diazo dye such as those disclosed in US. Pat. No.

3,409,433, an anthraquinone dye such as those disclosedin US. Pat. Nos. 3,575,704 and 2,865,752, a dye having a nitro group, and a metal chelate dye such as those disclosed in US. Pat. No. 3,364,029 is preferably used. The amount of the color coupler can range from 2mole to l/ 100 mole per one mole of silver halide, preferably 1 mole to 1/60 mole.

The finished silver halide emulsion in this invention may be applied on any photographic support such as a glass sheet, a cellulose acetate film, a cellulose acetate butyrate film, apolyester film, a photographic paper, a paper coated with baryta or a polyolefin, or a synthetic paper. A suitable coating amount of the silver halide photographic emulsion can range from 5 mg. to 200 mg., preferably from mg. to 100 mg. per 100 cm based on the amount of silver.

The color photographic material of this invention may be one having only one silver halide photographic emulsion layer on a support or having multi-layers of silver halide photographic emulsions on a support. Furthermore, an intermediate layer may be disposed betweenthe two silver halide photographic emulsion layers on a support. Still further, an antihalation layer may be formed on the back side of the support of the color photographic material of this invention or a protective layer or a filter layer may be formed on the silver halide photographic emulsion layer of the color photographic material.

Now, specific examples of producing the silver halide photographic emulsions used in this invention will be illustrated in greater detail below. Unless otherwise indicated all parts and percents are by weight.

Example 1 (Emulsion A) To a first liquid prepared by heating to 60C a mixture of 8 g of inactive gelatin, 5 cc of a one normal aqueous solution of potassium bromide, and 500 cc of water were added with stirring over a period of 50 minutes a second liquid prepared by dissolving 100 g of silver nitrate in 500 cc of water under heating to 60C and a third liquid prepared by dissolving 70 g of potassium bromide in 150 cc of water under heating to 60C and then the mixture was subjected to physical ripening for 5 minutes. Then, after adding to the mixture cc of a 0.2 normal aqueous solution of potassium iodide, the pAg of the mixture was adjusted to 6.0 using an aqueous silver nitrate solution. Furthermore, after adding to the mixture hydrazine and potassium chloroaurate, the pH of the resultant mixture was adjusted to 10 using an aqueous sodium hydroxide solution to complete the ripening. Then, the mixture was neturalized with citric acid and washed with water. Thereafter, a fourth liquid prepared by dissolving 75 g of inactive gelatin in 300 cc of water was added to the above-prepared mixture to provide the silver halide emulsion. The mean grain size of the silver halide emulsion thus prepared was about 0.2 micron and the emulsion contained grains of a normal tetragonal system having a (100) plane.

(Comparison Emulsion a) To a first liquid prepared by heating to 60C a mixture of 10 g of inactive gelatin, 5 cc of a one normal aqueous solution of sodium chloride, and 500 cc of water were added with stirring over a period of min-- utes a second liquid prepared by dissolving 100 g of silver nitrate in 500 cc of water at 60C and a third liquid prepared by dissolving 23g of sodium chloride and 23 g of potassium bromide in 150 cc of water and adding further 50 mg of potassium hexachloroiridate (K lrCl while maintaining the mixture at 60C. Thereafter, 15 cc of a 0.2 normal aqueous solution of potassium iodide was added to the mixture and after reducing the temperature thereof, the mixture was washed with water. Furthermore, the mixture was melted and after adjusting the pAg thereof to 4.0, hydrazine and potassium chloroaurate were added to the mixture. Then, after adjusting the pHof the mixture to 10, the mixture was ripened for 10 minutes and then the pH thereof was neutralizedto 6.5 using citric acid; After reducing the temperature, the mixture was washed with water and the mixture was melted. Then, the pAg of the melt was adjusted to 7.0 by adding thereto a mixed solution of an aqueous sodium chloride solution and aqueous potassium bromide solution and then a fourth solution prepared by dissolving g of inactive gelatin in 300 cc of water was added to the resultant mixture to provide the comparison silver halide emulsion. The mean grain size of the silver halide emulsion was about 0.15

.micron and the substantially all of the grains of the silver halide contained the grains of a normal tetragonal system having a plane.

Now, the fact that the silver halide emulsion A prepared above was the silver halide photographicemulsion having substantially no free electron trap in the silver halide grains will be shown by the following experi ments.

Experiment 1 Table 1 No. Emulsion Compound Used for Characteristic Used Sensitization Curve (100 g) (mole concentration) 1 Emulsion A Compound 5-] Curves l and 2 (8 X 10) 40 CC in FIG. 1 2 Comparison Comparison compound a Curves 3 and 4 Emulsion a (2 X 10') 4 cc and in FIG. 2

Comparison compound b 8 x 10') 4 cc Each of the samples thus prepared was exposed using an optical wedge to blue light through a k.31 Filter made by the Fuji Photo Film Co., Ltd. by using a tungsten lamp of 2854K under a normal temperature and normal pressure. The sample, then, was developed in the following developing solution for 2 minutes at 20C and fixed at 20C for 20 minutes in a fixing solution having the following composition to provide a strip:

Water to make By measuring the density of the strip using a S-type Densitometer made by the Fuji Photo Film Co., Ltd., the charactristic curve was obtained. The results obtained are shown as the curve 1 in FIG. 1 of the accompanying drawings and also as the curve 3 in FIG. 2.

On the other hand, thesame sample prepared above was allowed to stand under vacuum conditions of about mm Hg using an oil diffusion pump for about l7 hours at normal temperature to conduct the degassing. Thereafter, the sample was exposed using an optical wedge through a window of the vacuum vessel to blue light through the K-31 Filter using a tungsten lamp of At use, the composition was diluted with water in a volume ratio of l l.

The formulae of the Comparison Compounds (a) and (11) used in the experiment are shown below:

Comparison Compound (a):

Comparison Compound (b):

H5020 NO:

CH: CHa'S O 3' The r'sluiiQGi the s ensit ometry Table 2.

Table 2 Sample (A) D,,,,,, D,,,,,,. Sens. D,,,,,, D, Sens.

(Emul.A) No. 2 (Comp.

Emul. a)

0.04 1.04 l l0 0.07 1.06 l.ll

2854K under the same vacuum conditions as described above. The sample was also developed and fixed as described above and also subjected to sensitometry under the same conditions as described above. The characteristic curves thus obtained are shown as the curve 2 in FIG. 1 of the accompanying drawings and as the curve 4 in FIG. 2. The apparatus used for the evacuation degassing and exposure were similar in principle to those conducted by W. C. Lewis and T. H. James (as described in W. C. Lewis et al., Photographic Science and Engineering; Vol. 13, No. 2, 54 (1969)).

It will be understood from the characteristic curves of FIG. 1 and FIG. 2 that the Emulsion A was the silver halide emulsion of this invention having substantially no free electron trap in the silver halide grains, while the Comparison Emulsion a was not such a silver halide emulsion of this invention.

Furthermore, when the emulsion A was used alone without using the compound for sensitization (for in-' stance, without the Compound S-l a reversal image was hardly obtained, while when the Comparison Emulsion a was used alone, the reversal image could be obtained and thus the effect of the evacuation degassing was less.

The composition of the developing solution used in the above process was as follows:

Composition of the Developing Solution Water (about 50C) Metol 3 g Potassium Bromide 2 g Water to make 1,000 cc In the above table, (A) designates normal temperature and normal pressure; (B) designates after evacuation degassing; D,,,,-, designates minimum optical density; D designates maximum optical density; and Sens. designates sensitivity, the value of logE at the point of D /Z.

40 As shown in Table 2, in Sample No. l in which the ,Emulsion A of this invention was used, the sensitometry under the evacuation condition showed that the D,,,,-, of the sample thus treated was more than 100 percent higher than D of the sample which had not been subjected to the evacuation condition, and, the

sensitivity of the Sample No. l subjected to the evacuation treatment was almost lost. On the other hand, in the Sample No. 2 in which the Comparison Emulsion a was used, the D,,,,-,, was less than 7 percent of the D of the sample which had not been subjected to the evacuation treatment, and, the sensitivity of the Sample No. 2 was hardly reduced by the evacuation treatment.

Experiment 2 Each of the original emulsions prepared by the same added a dispersion of the above indicated Color Coupler (G7) in an amount of 50 g per g of the emulsion. On the other hand, a5 percent aqueous solution of the Comparison Coupler (c) described above was prepared using a one normal aqueous solution of sodium hydroxide and after the aqueous solution was 5 added to the sensitized emulsion prepared above so that the amount of the coupler was an equimolar amount to the Color Coupler (C-7), the emulsion was neutralized with aqueous citric acid solution.

g of the Color Coupler (C-7) was dissolved by heatmg m cc of tricresy] ph h t d h solution was Composition of the Bleaching Solution added to a 10 percent aqueous solution of inactive gel- Potassium Nitrate g am at 60C. After, furthermore, adding 5 cc of a 5 perl Femcyan'd" B Potassium Bromide 8.0 g cent aqueous solution of sodium dodecylbenzene sulfo- 5 Bmic Acid g nate to the emulsion, it was dispersed therein using an ultrasonic oscilator. The mean grain size was 0.12 miwater to make (PH 72) I cron. By quenching the dispersion, an emulsion of the Coupler G7 was obtained.

Table 3 No. Compound Used for Coupler Photo. Charact.

Sensitization per Used Sens. D Emulsion A lOO g (logE) 5 S-1 8 x l0mole) C47 l.28 0.04 Curve 5 50 cc in FIG. 3 6 do. Comp.

Coupler 2.40 0.12 Curve 6 (c) in FIG. 3 7 Compound (b) (2 X lO mole) C-7 0.55 Curve 7 4 cc in FIG. 3 8 do. Comp.

Coupler 0.6 Curve 8 (cl in FIG. 3

By adding a 2 percent aqueous solution of N- Composition of the Hardening Fixing Solution tetradecyl-l\l,N-di(polyoxyethylene)-a-betain in an amount of 10 cc/ 1 kg of emulsion and an appropriate Ammonium Thiosulfate 120.0 g amount of a dichlorotriazinic hardening agent to the zg 'g'g g 21 5 silver halide emulsion containing the color coupler thus Formalin 35-40% 40.0 c c obtained in essentially the same manner as described in make (pH 95 1 Experiment 1, a finished emulsion was obtained. After o h emulslonliodsiand Ti 2 The density of the strip thus obtained was measured e 2 y 1: u 056 i through a green filter, whereby a characteristic curve m ry t m ness 0 out mlcronsh(seei) Z was obtained. The results of the sensitometry are Each of the four kinds of samples t us 0 taine was shown in Table 3 and FIG exposed f Opncal wedge to blue l'ght enough a From these results, it will be understood that the 31 Fllter a tungsten lamp of 2854 K under electron acceptors of this invention gave excellent renormal temperalufe and normal pressure and P sults in comparison with the comparison compounds. It Cessed the followmg y 40 will further be understood that even if the same eleca tron acceptor as in this invention and also the chemical 1. Color Development 29.5 C 6 min. 2. Stop Fixing 2 d structure of the functional nucleus for dye forming of 3. Rinsing 2 do. the coupler were the same, the sample of this invention gajj g ui 3 3:- had a higher sensitivity and the sample of this invention 6. Hardening Fixing 4 an was excellent in clearness of the highlight portions in 7. wr ter ashing g comparison with the comparison sample. 3 gf 'gf The same procedure as described above was repeated while changing the method of dispersing the The compositions of the processing baths used in the coupler. That is to say, a dispersion containing coarse above processings are shown below: coupler oil drops having a particle size of about 2 microns was prepared and after preparing a sample in the Composition of the Color Developing Solution same way 38 Shown in Table 3, N0. 5, the sensitometry was conducted on the sample under the same condig gf 2 29 3-8 g tions as described above, the results of which are shown z l' s zi Sulfa. 5 as curve 9 in FIG. 3 of the accompanying drawings. Potassium Bromide 0. g From the results, it has astonishingly been found that gg ig gfigfgi Mme 2'8 2 the sensitivity was only about 30 percent of the sample Benzyl Alcohol 15.8 cc of this invention prepared as described above and also methylene Glycol 200 CC the clearness of the highlight portion was poor. This is i' i igl' g f g z rg" 8 0 g considered to be caused by the size of the dispersed wiiterio make 1 liter coupler particles as being too coarse in comparison (PH 10-6) with the grain size of the silver halide grains in the silver halide emulsion, and as a result they are brought into Composition of the Stopping Fixing Solution contact with the silver halide grains and the coupler ad- I 120 0 sorbs on the silver halide grains. g 'z g g gf' gg gfs 5 Consequently, even if the oil-soluble color coupler of Glacial Acetic Acid 10.0 g this invention is used, disadvantageous results will be Waiter to make 1 liter obtained if the coupler is not sufi'iciently dispersed. The dispersion state of the coupler can be controlled by 23 controlling the particle size of the oil droplets of the coupler. That is to say, by using the coupler dispersion containing the oil droplets of a coupler having a mean particle size of less than about 1 micron, the objects of l Thereafter, 500 g of the dispersion of the coupler prepared by the method shown in Experiment 2 of Example was added to the above mixture and melted. The coupler used is shown in Table 4.

this invention can be attained. Then, by adding to the mixture cc of a 2 percent When the samples shown in Table 3 were subjected aqueous solution of N-tetradecyl-N,N-di-polyoxyethyl to the evacuation treatment or degassing under the betaine and 10cc of a 2 p cent aqu ous ution conditions as shown in Experiment 1 and exposed in 4-dichloro-6-hydroxy-s-trla a finlshed fimulSlOfl vacuo in situ, reversal images were hardly obtained on Was Oblamedcolor development. 10 The finished emulsion thus prepared was applied to EX eriment 4 a transparent cellulose triacetate film in a dry thickness p of about 3 microns. The photosensitive material ob- 40 cc of a 8 X 10 mole 9 of h compognd tained was exposed using an optical wedge to a tung- S-l was added to 100 g of the Comparison Emulsion Sten lamp f 54 under normal temperature d (a) and after further adding to the mixture 50 g of the l 5 normal pressure emulsion of the Coupler (C- I the resultant emulsion The exposed sample was subjected to a sensitometric was apphed to a cellulose macetate film as Expat" .test according to the procedure as described in Exammam 1 or 3 to Provlde sample 9 TWO Sheets of ple l. The results are shown in Table 4. Furthermore, such a Sample were Prepared by exposing the photosensitive materials prepared The emulsion of the Coupler (C-l) used above was above using a spectrograph d b Narumi Shokai P by repeatfng the Sams procedur? as descnbed and developing them as described above, spectro- Experiment 2 the P P of the photographs were obtained. The results obtained are Coupler The mean Partlcle We of the 011 dropshown in FIG. 5 to FIG. 14 of the accompanying drawlets of the coupler was less than 0.12 micron. i

" Table 4 No Coupler Used Sensitizcr Used Photographic (A) (mean particle Designation Amount Properties size in 1) X l0' mole) Color of Relative Image Humidity 9 C-l 0.l2 8-] 0.32 Yellow l00' FIG. 5 l0 C-l (0.l2 5-2 0.40 Yellow 50 FIG. 6 ll 06 (0.20 s-s 0.32 Yellow FIG. 7 l2 (-7 (0.20) 5-7 0.45 Magenta 63 FIG. 8 l3 C-IO (0.l5) 5-8 0.32 Magenta 450 FIG. 9 I4 09 (0.15 5-9 0.32 Red 400 FIG. l0 l5 (-2 (0.!8) Sl0 0.32 Yellow 10 FIG. ll 16 C-l3 0.ll 8-12 0.40 Cyan 32 Flo l2 l7 C-l2 0.09 5-13 0.40 Cyan 200 Y FIG l3 l8 C-i4 (0.25 S-l4 0.32 Cyan 160 FIG 14 In the above table. (A) means spcctrophotography.

The two samples were exposed in the same way as shown in Experiment 1 and one of the samples was subjected to black and white development, while the other was subjected to the color development procedures as described in Experiment 2. Then, the density of each sample was measured through a blue filter. In this experiment, the former gave a black and white image having good clearness of the highlight portion as shown by curve 10 in F IG. 4, while the latter gave poor clearness of the highlight portion and low sensitivity as shown b curve 11 in FIG. 4.

These results showed that the use of the Comparison Emulsion (a), i.e., the silver halide emulsion having free electron trap in the silver halide grains was disadvantageous for the attainment of the objects of this in- 60 vention.

Example 2 By repeating Example 1, a fogged silver halide Emulsion A was prepared. After adding the electron accep- 5 tor shown in Table 4 to one kilogram of the emulsion prepared, the mixture was stirred for 20 minutesat 40C. I

The values of E and E of the dyes used in the experiment are shown in Table 5. It will be understood that the values of E and E of the dyes used satisfied the above-indicated values (E 2 about 1 .0 volt, E about 0.7 volt).

According to the same procedures as described above, the finished emulsions as shown in Table 6 were prepared and each of the emulsions was applied to a polyethylene coated paper, which had been subjected to a corona discharging treatment for improving the ad- -hesivity of the emulsion. When the photosensitive material thus prepared was subjected to the sensitometric test as described above, a color positive image having good clearness of the highlight portion could be obtained.

26 7. The color photographic material of claim 1, wherein said electron acceptor is selected from the group consisting of compounds of the general formula I While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

What is claimed is:

l. A color photographic material having at least one silver halide photographic emulsion layer containing chemically fogged direct positive silver halide grains, said silver halide photographic emulsion layer simultaneously satisfying the following criteria:

1. said silver halide photographic emulsion having substantially no free electron trap in said silver halide grains;

2. said silver halide photographic emulsion having adsorbed on the surface of said silver halide grains a desensitizing dye electron acceptor having a water-soluble anionic group or an anionic group forming a betaine structure, selected from the class consisting of at least one sulfo group, carboxy group or phosphoric acid group, said electron acceptor having an E value equal to or more positive than l.0 volt and an E value equal to or' more positive than 0.7 volt;

3. said silver halide emulsion containing droplets of an oil-soluble color coupler dispersed therein, the mean droplets size in diameter of said coupler being smaller than about one micron; and

4. said silver halide emulsion layer forming a color image on development with a silver halide developing solution containing a phenylenediamine as the color developing agent.

2. The color photographic material of claim 1, in which said silver halide grains contain at least 50 mole percent bromine ions and less than 2 mole percent iodine ions and further in which said silver halide grains have a mean grain size of less than 0.7 micron.

3. The color photographic material of claim 1, in which said electron acceptor has at least one sulfoalkyl group or carboxyalkyl group.

4. The color photographic material of claim 1, in which the silver halide grains have a mean particle size ranging from 0.04 micron to 2 microns.

5. The color photographic material of claim 1, in which said silver halide is silver bromide, silver iodobromide. silver chlorobromide, or silver chloroiodobromide.

6. The color photographic material of claim 1, wherein said electron acceptor is present in said emulsion in an amount of from 1 X 10 mol to X 10 mol per mol of silver halide.

wherein B represents an atomic group necessary for forming a heterocyclic ring, R represents an alkyl group, an unsaturated aliphatic group, or an aryl group, A represents a phenol group having at least one nitro group, a naphthyl group or a heterocyclic ring nucleus, m and n each represents an integer of l or 2, and X represents an anion, and wherein at least one of R B or A. contains at least one of a sulfo group, a carboxyl group, or a phosphoric acid group;

General Formula ll:

wherein Z represents an oxygen atom, a Nl-l-- group, or a Cl-l=group, Z represents an atomic group necessary for forming a cycloheptatriene ring, A represents a hydrogen atom, an oxygen atom, or a halogen atom, L and L each represents a methine group, Z represents an atomic group necessary for forming a heterocyclic ring, X, n, and m have the same meaning as described above, and R represents an alkyl group having at least one sulfo group, a carboxyl group or a phosphoric acid group or an unsaturated aliphatic p;

General Formula Ill:

"I-IIQHZS z.-L,=L2o: oH-orr r'-i-m n-l i wherein Z, represents an indole nucleus, a carbazole nucleus, or a phenothiazine nucleus, Z represents an atomic group necessary for forming a heterocyclic ring, R represents an alkyl group, an unsaturated aliphatic group, or an aryl group, at least one of Z Z or R containing at least one of a sulfo group, a carboxyl group, or a phosphoric acid group, L and L each repwherein Z, and Z each represents an atomic group I necessary for forming a S-membered or 6-membered heterocyclic nucleus, at least one of said Z and Z representing an atomic group necessary for forming a S-membered or 6-membered heterocyclic nucleus selected from the group consisting of indolc, nitrosubstituted indolenine, imidazoquinoxuline, nitrosubstituted benzothiazole, pyrrolopyridine, or nitrosubstituted benzoxazole, having an electron accepting property or a desensitizing action, R and R each represents an alkyl group, an unsaturated aliphatic group, or an aryl group, at least one of said R and R containing a sulfo group, a carboxyl group, or a phosphoric acid group, q represents an integer of l, 2, or 3, r and s each represents an integer of l or 2, L L and L each represents a methine group, and X and m are as described above.

8. The color photographic material of claim 7, wherein said heterocyclic nucleus is an oxazole nucleus, a benzoxazole nucleus, a naphthoxazole nucleus, a thiazole nucleus, a benzothiazole nucleus, a naphthothiazole nucleus, a selenazole nucleus, a benzoselenazole nucleus, a naphthoselenazole nucleus, an indolenine nucleus, an indole nucleus, an imidazole nucleus, a benzoimidazole nucleus, an imidazoquinoxaline nucleus, or a pyrrolopyride nucleus.

9. A color photographic element comprising a support having coated thereon a layer of the color photographic materials of claim 1.

10. The color photographic material of claim 9, wherein said support is a glass sheet, a cellulose acetate film, a cellulose acetate butyrate film, a polyester film, a photographic paper, a buryta coated paper, a polyolefin coated paper, or a synthetic paper.

11. The color photographic material of claim 1, wherein said anionic group is a sulfo group.

12. The color photographic material of claim 1, wherein said anionic group is a carboxy group.

13. The color photographic material of claim 1, wherein said anionic group is a phosphoric acid group.

14. The color photographic material of claim 1, wherein a silver halide photographic emulsion having substantially no electron traps is determined according to the following test procedures:

the silver halide emulsion layer is coated to a thickness of less than about 5 microns, exposed to blue light and white light, developed for 2 minutes at 20C. using developer D72 or developer D- l 9, and fixed, to obtain a characteristic curve of the direct positive type, a sample prepared in the above manner compared to a sample prepared identically but being degassed for longer than I? hours at normal temperature under a reduced pressure of 10" mm/Hg illustrating the following relationship: the minimal optical density value D of the degassed sample being higher than the optical density corresponding to 30 percent of the maximum optical density value D of the non-degassed sample or the sensitivity of the degassed sample at a point of one-half of the maximum optical density thereof being lower than 65 percent of the sensitivity of the non-degassed sample at the point of one-half of the maximum optical density thereof, such a silver halide photographic emulsion having substantially no electron traps.

15. The color photographic material of claim 1, wherein said color coupler has an active methylene group substituted with a splitting-off substituent selected from the group consisting of a halogen atom, an

,aryldiazo group, an arylthio group, an aryloxy group or a carboxyl group.

16. The color photographic material of claim 1, wherein said color developing solution further contains a small amount of a sulfite and has a pH greater than 9.8.

17. The color photographic material of claim 1, wherein the grain size of the silver halide ranges from 0.04 microns to 2 microns.

Claims (23)

1. SAID SILVER HALIDE PHOTOGRAPHIC EMULSION HAVING SUBSTANTIALLY NO FREE ELECTRON TRAP IN SAID SILVER HALIDE GRAINS;

2. SAID SILVER HALIDE PHOTOGRAPHIC EMULSION HAVING ADSORBED ON THE SURFACE OF SAID SILVER HALIDE GRAINS AN ELECTRON ACCEPTOR HAVING A WATER-SOLUBLE ANIONIC GROUP OR AN ANIONIC GROUP FORMING A BETAINE STRUCTURE;

2. The color photographic material of claim 1, in which said silver halide grains contain at least 50 mole percent bromine ions and less than 2 mole percent iodine ions and further in which said silver halide grains have a mean grain size of less than 0.7 micron.

2. said silver halide photographic emulsion having adsorbed on the surface of said silver halide grains a desensitizing dye electron acceptor having a water-soluble anionic group or an anionic group forming a betaine structure, selected from the class consisting of at least one sulfo group, carboxy group or phosphoric acid group, said electron acceptor having an Ered value equal to or more positive than -1.0 volt and an Eox value equal to or more positive than 0.7 volt;

3. said silver halide emulsion containing droplets of an oil-soluble color coupler dispersed therein, the mean droplets size in diameter of said coupler being smaller than about one micron; and

3. The color photographic material of claim 1, in which said electron acceptor has at least one sulfoalkyl group or carboxyalkyl group.

3. SAID SILVER HALIDE EMULSION CONTAINING DROPLETS OF AN OILSOLUBLE COLOR COUPLER DISPERSED THEREIN, THE MEAN DROPLETS SIZE IN DIAMETER OF SAID COUPLER BEING SMALLER THAN ABOUT 1 MICRON; AND

4. SAID SILVER HALIDE EMULSION LAYER FORMING A COLOR IMAGE ON DEVELOPMENT WITH A COLOR DEVELOPING SOLUTION CONTAINING A PHENYLENEDIAMINE OR A DERIVATIVE THEREOF AS THE COLOR DEVELOPING AGENT IS DISCLOSED.

4. The color photographic material of claim 1, in which the silver halide grains have a mean particle size ranging from 0.04 micron to 2 microns.

4. said silver halide emulsion layer forming a color image on development with a silver halide developing solution containing a phenylenediamine as the color developing agent.

5. The color photographic material of claim 1, in which said silver halide is silver bromide, silver iodobromide, silver chlorobromide, or silver chloroiodobromide.

6. The color photographic material of claim 1, wherein said electron acceptor is present in said emulsion in an amount of from 1 X 10 6 mol to 5 X 10 3 mol per mol of silver halide.

7. The color photographic material of claim 1, wherein said electron accepTor is selected from the group consisting of compounds of the general formula I

8. The color photographic material of claim 7, wherein said heterocyclic nucleus is an oxazole nucleus, a benzoxazole nucleus, a naphthoxazole nucleus, a thiazole nucleus, a benzothiazole nucleus, a naphthothiazole nucleus, a selenazole nucleus, a benzoselenazole nucleus, a naphthoselenazole nucleus, an indolenine nucleus, an indole nucleus, an imidazole nucleus, a benzoimidazole nucleus, an imidazoquinoxaline nucleus, or a pyrrolopyride nucleus.

9. A color photographic element comprising a support having coated thereon a layer of the color photographic materials of claim 1.

10. The color photographic material of claim 9, wherein said support is a glass sheet, a cellulose acetate film, a cellulose acetate butyrate film, a polyester film, a photographic paper, a buryta coated paper, a polyolefin coated paper, or a synthetic paper.

11. The color photographic material of claim 1, wherein said anionic group is a sulfo group.

12. The color photographic material of claim 1, wherein said anionic group is a carboxy group.

13. The colOr photographic material of claim 1, wherein said anionic group is a phosphoric acid group.

14. The color photographic material of claim 1, wherein a silver halide photographic emulsion having substantially no electron traps is determined according to the following test procedures: the silver halide emulsion layer is coated to a thickness of less than about 5 microns, exposed to blue light and white light, developed for 2 minutes at 20*C. using developer D-72 or developer D-19, and fixed, to obtain a characteristic curve of the direct positive type, a sample prepared in the above manner compared to a sample prepared identically but being degassed for longer than 17 hours at normal temperature under a reduced pressure of 10 4 mm/Hg illustrating the following relationship: the minimal optical density value Dmin of the degassed sample being higher than the optical density corresponding to 30 percent of the maximum optical density value Dmax of the non-degassed sample or the sensitivity of the degassed sample at a point of one-half of the maximum optical density thereof being lower than 65 percent of the sensitivity of the non-degassed sample at the point of one-half of the maximum optical density thereof, such a silver halide photographic emulsion having substantially no electron traps.

15. The color photographic material of claim 1, wherein said color coupler has an active methylene group substituted with a splitting-off substituent selected from the group consisting of a halogen atom, an aryldiazo group, an arylthio group, an aryloxy group or a carboxyl group.

16. The color photographic material of claim 1, wherein said color developing solution further contains a small amount of a sulfite and has a pH greater than 9.8.

17. The color photographic material of claim 1, wherein the grain size of the silver halide ranges from 0.04 microns to 2 microns.

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