US3790388A

US3790388A - Direct positive color photographic materials

Info

Publication number: US3790388A
Application number: US00288826A
Authority: US
Inventors: K Shiba; S Kubodera; K Sano; A Okumura
Original assignee: Fuji Photo Film Co Ltd
Current assignee: Fujifilm Holdings Corp
Priority date: 1971-09-13
Filing date: 1972-09-13
Publication date: 1974-02-05
Anticipated expiration: 1991-02-05
Also published as: DE2244924A1; JPS4838149A; GB1389570A

Abstract

A direct positive color photographic material having a silver halide photographic emulsion layer containing chemically fogged silver halide grains, said silver halide emulsion layer containing a magenta color coupler precursor having a pyrazole nucleus substituted by an acyloxy group at the five-position. The direct positive color photographic material containing such a magenta color coupler precursor has a high sensitivity, shows good clearness in the highlight portions, and has improved stability.

Description

United States Patent [191 Shiba et al. Feb. 5, 1974 [5 DIRECT POSITIVE COLOR 2,706,685 4/1955 Salminen 96/100 PHOTOGRAPH: MATERIALS I 3,501,307 3/1970 lllingsworth 3,501,312 3/1970 Mac at al 96/107 [75] Inventors: Keisuke Shiba; Kazuya Sano; Akio Okumura; Seiiti Kubodera, all of Kanagawa, Japan Primary ExaminerJ. Travis Brown [73] Assignee: Fuji Photo Film Co., Ltd., $23 ,2 1 Flrm sughme Rothweu Mlon Kanagawa, Japan [22] Filed: Sept. 13, 1972 [21] Appl. No.: 288,826 [57] ABSTRACT A direct positive color photographic material having a [30] Forelgn Apphcatlon Pnomy Data silver halide photographic emulsion layer containing Se t. 13, 1971 Japan 46-71065 chemically fogged silver halide grains, said Silver ide emulsion layer containing a magenta color coupler [52] US. Cl 96/100, 96/56.5, 96/60 R, precursor having a pyrazole nucleus substituted by an 96/61 96/94 R, 96/107 96/108 acyloxy group at the five-position. Thedirect positive [51] Int. Cl G03c l/40 1 photographic material containing Such a [58] Field of Search 96/100, 107, 108 gema color coupler precursor has a high sensitivity, shows good cleamess in the highlight portions, and has 56] References Cited improved stability.

UNITED STATES PATENTS 2,436,130 2/1948 Weissberger et al. 96/100 10 Claims, 7 Drawing Figures PAIENTEBFEB 51914 Y 3199,39

FIG]

" mgsb 10 E RELATIVE VALUE 400 500 e00 700 WAVELENGTH m ,(nm)

400 500 600 70o WAVELENGTH 400 500 600 'YOOWAVELENGTH- v (nm) 400 500 600 YOOWAVELENGTH v (nm) 400 500 600 700 WAVELENGTH DIRECT POSITIVE COLOR PHOTOGRAPIIIC MATERIALS BACKGROUND OF THE INVENTION visible rays and by a subsequent one step of a series of materials is generally accompanied with specific difficulties in comparison with the production of negative photographic materials. In particular, the production of.

direct positive color photographic materials encounters more difficulties. A first difficulty is that a sufficiently high sensitivity is hard to obtain. A second difficulty is that sufficient clearness of the highlight portions is hard to obtain. A third difficulty is that the flowable silver halide photographic emulsion to be used is poor in stability and thus it is difficult to obtain consistent photo-.

graphic properties. A fourth difficulty is that color negative images appear in the highlight areas and thus the latitude tends to be narrow.

An object of this invention is to provide a direct positive color photographic material unaccompanied by the aforesaid difficulties.

SUMMARY OF THE INVENTION It has now been discovered that the above-described difficulties are overcome by this invention. That is to say, the above objects have been attained by using, as the photographic emulsion for the direct positive color photographic material, a chemically fogged direct positive silver halide photographic emulsion containing a color coupler precursor having a-pyrazole nucleus substituted by an acyloxy group at the five-position in the structural formula. The acyl moiety of the acyloxy group indicated above includes, in addition to an aliphatic or aromatic group attached to a carbonyl group (i.e., where the acyl group is aliphatic- II I C or aromatic l3 but also an aliphatic or'aromatic group attached to the carbonyl group through an oxygen atom (i.e., where the acyl group is aliphatic A first feature of the present invention is in the silver halide photographic emulsion used. That is to .say, the surface of the silver halide grains of the photographic emulsion has been chemically fogged.

A second feature of this invention is in the use of a magenta color coupler precursor having a pyrazole nucleus substituted by an acyloxy group at th e -p osition thereof is used.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS FIG. 1 is a graphical representation showing the photographic properties used in determining the characteristics of a silver halide emulsion used in this invention.

FIGS. 2-7 are spectrograms obtained for embodiments of the photographic material of this invention.

DETAILED DESCRIPTION OF THE INVENTION Silver halide direct positive photographic emulsions containing color couplers are known. For example, the direct positive silver halide photographic emulsions as described above are disclosed in the specifications of French Pat. Nos. 1,498,213; 1,520,823; 1,522,354; and 1,520,819; British Pat. Nos. 1,186,711; and 1,186,712; US. Pat. Nos. 3,501,307 and 3,501,312; and German Pat. Offenlegungsschrift No. 1,815.967.

Color couplers are those organic compounds which can form colored dyes in an aqueous solution containing a phenylenediamine derivative as the color developing agent and which is alkaline, preferably a pH of at least 9.8 in the presence of silver halide grains which have become developable by being fogged by exposure or by a chemical treatment. Color couplers can be said to have,'in principle, a certain reducing powerwith respect to the oxidation product of the color developing agent. As compounds useful as such color couplers, benzoylacetanilide derivatives, pivaloyl acetanilide derivatives, cyanoacetanilide derivatives, S-pyrazolone derivatives, indazolone derivatives, oxynaphthoic acid derivatives, and phenol derivatives are known.

The inventors have discovered that of these known color couplers the 5-'pyrazolone derivative, when it is incorporated in a direct positive silver halide photographic emulsion, greatly reduces the sensitivity of the emulsion, the clearness of the highlight portion, and also the stability of the emulsion. However, the 5- pyrazolone derivative, in contradistinction, is a coupler which has various excellent properties. That is to say, a S-pyrazolone derivative has an excellent coupling activity, gives a color image having excellent spectral absorptions, and also is easily available industrially.

However, the S-pyrazolone derivative, when it is used in direct positive silver halide emulsions, gives rise to disadvantages are improved remarkably by using a magenta color coupler precursor containing a pyrazole nucleus substituted with an acyloxy group at the 5- I position thereof.

Some of these effects have also been observed in regard to the benzoylacetanilide couplers, etc, although the 5-acyloxy group substituted pyrazole nucleus magenta color coupler precursor of this invention.

The silver halide photographic emulsions in this invention are generally classified into an A-type emulsion and a B-type emulsion.

That is to say, the A-type emulsion is a silver halide photographic emulsion which has been chemically fogged and has free electron trap nuclei in the silver halide grains:

A silver halide emulsion of this type gives a reversal image by sufficient exposure. Also, various attempts have been made to increase further the reversivity, i.e., the reversal sensitivity 'of silver halide emulsions, to improve additionally the clearness of the highlight portions, and to prevent further the formation of negative images at the highlight areas.

Firstly, some attempts have been made to form positively electron trap nuclei in the silver halidegrains for preventing the free electrons from being recomthe extent of the effects may differ from that by use of bined with the positive holes. This method has been known for a long time as a means of increasing the internal sensitivity of silver halide grains. That is to say, there are a method wherein iodide ions are incorporated in silver halide emulsions that have not been chemically ripened; a method wherein silver halide grains having sensitive nuclei obtained by chemical ripening are converted into inside nuclei by converting the outer surfaces of the silver halide grains with another silver halide; and further a method wherein a salt of a metal belonging to Group VIII or Group lb of the periodic table is incorporated in the silver halide emulsions in the step of precipitating the silverhalide are known (see, US. Pat. Nos. 2,401,051; 2,717,833; 2,976,149; and 3,023,103; British Pat. Nos. 707,704; 1,097,999; and 690,997; French Pat. Nos. 1,520,822; 1,520,824; 1,520,817; and 1,523,626; Japanese Pat. Publication Nos. 4125/1968 and 29,405/1968; and Belgian Pat. Nos. 713,272; 721,567; and 681,768).

Secondly, electron acceptors and/or halogen acceptors are adsorbed on the surface of silver halide grains, whereby, in many cases, the silver halide grains are spectrally sensitized toincrease the sensitivity andalso the clearness of the highlight portions is improved. The halogen acceptors used in this invention may be defined as M-band type sensitizing dyes. The electron acceptors used in this invention also includes the socalled sensitizers and may be defined as materials having the ability to capture free electrons generated in silver halide grains. Those definitions are well known to one skilled in the art.

Thirdly, silver halide grains having the properties that the silver halide grains have less positive hole-capturing sites in the grains and the positive holes have suitable sizes for attacking the fogged nuclei disposed on'the surface of the silver halide grains. Bromide ions or iodide ions may also be used together with the halogen acceptor or the electron acceptor.

On the other hand, the B-type emulsion is a silver halide photographic emulsion that has substantially no free electron trap nuclei in the silver halide grains and which has been chemically fogged:

The original silver halide emulsion of this type can give less or no reversal images by itself and a direct positive image can be obtained using such a silver halide photographic emulsion by adsorbing the electron acceptor on the surface of the silver halide grains. A silver halide emulsion of this type has the following advantages. Firstly, because there are substantially no free electron trap nuclei in the silver halide grains, negative images rarely appear at the highlight area and thus a broad latitude is obtained. The free electron-trapped nuclei of the silver halide grains tend to become developing centers. In particular, a color developing solution containing phenylenediamine as the color developing agent has an essential property of developing readily the developing centers in the silver halide grains. Secondly, the silver halide grains have no sites or a substantially smaller member of sites for capturing free positive holes in the silver halide .grains. Electron trap nuclei in silver halide grains tend to become, disadvantageously, centers for recombination with positive holes. Thirdly, the use of the electron acceptor is inevitable. The properties of the electron acceptor exhibit an important role in the photographic properties (see, Japanes efat. application No. 24,967/1971).

The A-type emulsion can be clearly and readily distinguished from the B-type emulsion by any of the following manners:

First, as original silver halide emulsions, the A-type emulsion can be a direct positive emulsion by itself, while the B-type emulsion cannot give rise to sufficient positive images by itself.

Secondly, as finished silver halide emulsions, they can be distinguished each other by the following manner.

That is to say, the finished silver halide emulsion is applied to a support such as a polyethylene terephthal-' ate film, a cellulose acetate film, or a glass sheet in a thickness below about 5 microns. In this case, the

amount of the coated silver is preferably so selected that the maximum optical density obtained by development is 0.1 to 1.5. The coated sample is cut into a strip and the strip is exposed behind an optical wedge to blue light obtained by passing the light from a tungsten lamp (2,854 K) through a Wratten Filter No. 478 or a K-3l Filter made by the Fuji Photo Film Co., Ltd.. Also,

. white light may be used in the exposure. In this case,

one of the samplesis exposed at normal temperatures and normal pressures, while the other sample is evacuated at room temperature for more than 17 hours under a high vacuum of below 10" mm. Hg and then exposed under the high vacuum. Thereafter, each of the samples is developed for 2 minutes at 20 C and then fixed. As the developing solution, a D-72 developing solution, a D19 developing solution, or a Papitol developing solution having the following composition is used.

Compositionof D 72 Developing Solution N-Methyl-p-Aminophenol. Sulfate Sodium Sulfite (Anhydrous) Hydroquinone Sodium Carbonate (Anhydrous) Potassium Bromide Water to make Composition of D-l9 Developing Solution Composition of Papitol Developer Solution Water to make At use, the composition is diluted with water in a 1 l by volume ratio.

By measuring the density of the strips thus obtained, the characteristic curves are obtained. The characteristic curve (a) of the strip which was exposed under normal temperatures and normal pressures and the characteristic curve (b) of the strip which was exposed at normal temperatures under vacuum are shown in Table 1 and in FIG. 1 of the accompanying drawings.

When the results of the measurement satisfy the following two factors, that the silver halide photographic emulsion used for the sample strip has substantially no free electron trap nuclei in the silver halide grains is defined. That is to say, (1) where the minimum optical density (clearness of the highlight portions) of the latter strip described above, D,,,,,,(b), is 30 percent or more of the maximum density (fogged density at the unexposed area) of the former strip, D,, (a); i.e., Dmi1l(b) Q.3 D ga) and (2) the sensitivity Sb at the point of /2 of the maximum density of the latter strip described above is reduced to 65 percent or less of that Sa of the former strip; i.e., Sb 0.65 X Sa.

This definition can be applied additionally to direct positive photographic materials as well as direct positive color photographic materials (in this case the photographic materials are developed using a developer formulation specific to the photographic material). The aforesaid method discovered by the inventors is quite clear, precise, and reasonable method based mainly on the efficiency of the free electrons generated in silver halide grains being captured by the electron acceptor adsorbed on the surface of the grains (see, Japanese Pat. Publication No. 24,967/1971).

In the present invention any types of the emulsions as indicated above may be used but the use of the B-type emulsion is particularly preferable. An example of preparing the B-type emulsion will be illustrated below.

PREPARATION EXAMPLE 1 To a first liquid prepared by dissolving 8g of inert gelatin and 5 cc of a 1N aqueous solu tion gfpotas sium bromide in 500 cc of water'by h eating the mixture to 60 C were added, a second liquid prepared by dissolving 100g of silver nitrate in 500 cc of water by heating the mixture to 60 C and a third liquid prepared by dissolving 70g of potassium bromide in 1,500 cc of water by heating the mixture to 60 C and then the mixture was subjected to physical ripening for 5 minutes. Then, cc ofa 0.2 N solution of potassium iodide was added to the emulsion thus ripened and after adjusting the pAg thereof to 6.0 using an aqueous silver nitrate solution, hydrazine sulfate and potassium chloroaurate were added to the emulsion. Then, after further adjusting the pH of the mixture to 10 using an aqueous sodium hydroxide solution, the mixture was ripened further. Then, the mixture was neutralized with citric acid and washed with water. Furthermore, after melting the resultant mixture, a fourth liquid prepared by dissolving 75g of inert gelatin in 300 cc of water was added to the mixture to provide a silver halide original emulsion. The silver halide grains in the emulsion were grains of a regular tetragonal system having a mean grain size of about 0.2 micron and a (1,0,0) plane.

A typical example of preparing the A-type. emulsions will be illustrated below.

PREPARATION EXAMPLE 2 To a first liquid prepared by dissolving 10g of inert gelatin and 5 E 9 N aq ussq ytiqnp sqdi n chloride in 500 cc of waterat 60 C were added with stirring simultaneously a second liquid prepared by dissolving g of silver nitrate in 500 cc of water at 60 C and a third liquid prepared by dissolving 23g of sodium chloride and 23g of potassium bromide in cc of water, adding further 50 mg of potassium hexachloroiridate (IV) (K IrCl to the solution, and maintaining the mixture at 60C over a period of 20 minutes. Thereafter, 15 cc of a 0.2 N aqueous solution of potassium iodide was added to the mixture, the resultant mixture was set by reducing the temperature thereof, and washed with water. Then, after meltingthe mixture, the pAg thereof was adjusted to 4.0 and hydrazine sulfate and potassium chloroaurate (III) were added to the mixture. After adjusting, then, the pH of the mixture to 10, the mixture was ripened for 10minutesand then neutralized to a pH of 6.5 using citric acid. Thereafter, the mixture was set by reducing the temperature thereof and washed with water. After melting the mixture, a mixture of a sodium chloride solution and a potassium bromide solution was added to the mixture and then the pAg thereof was adjusted to 7.0. Thereafter, a fourth liquid prepared by dissolving 75g of inert gelatin in 300 cc of water was added to the mixture to provide a silver halide original emulsion. The silver halide grains in the emulsion prepared above were the grains of a regular tetragonal system having a mean grain size of about 0.15 micron and substantially, all of the grains exhibited the (1,0,0).

The electron acceptors which can be used in this invention are disclosed in, e.g., the specifications of U.S. Pat. Nos. 3,023,102; 3,314,796; 2,901,351; and 3,367,779; British Pat. Nos. 723,019; 698,575; 698,576; 834,839; 667,206; 748,681; 796,873; 975,887; 905,237; 907,367; 940,152; and 1,075,654; French Pat. Nos. 1,520,824; 1,518,094; 1,518,095; 1,520,819; 1,520,823; 1,520,821; and 1,523,626; Belgian Pat. Nos. 722,457 and 722,594; and Japanese Pat. Publication Nos. 13167/1968 and 14500/1968.

Also, the halogen acceptors which can be used in this invention are disclosed in, e.g., the specifications of U.S. Pat. Nos. 2,497,876 and 3,364,026; French Pat. Nos. 1,520,822 and 2,012,545; British Pat. No. 655,009; and German Pat. No. 1,190,331. The electron acceptor and the halogen acceptor used in this invention are preferably ones having at least one sulfo group, carboxyl group, or phosphate group.

The direct positive silver halide photographic emulsion in this invention may be chemically fogged in the following way. That is to say, fogged nuclei are obtained by adding to the silver halide emulsion an inorganic reducing compound such as stannous chloride, sodium borohydride, and cuprous chloride or by adding an organic reducing compound such as hydrazine, a hydrazine derivative, formalin, thiourea dioxide, a polyamino compound, an amine borane, and methyldichlorosilane. Also, metal ions. having a lower ionization potential than silver ions or halide ions may be used together with the above-indicated reducing agent for further improving the stability of the fogged nuclei and facilitating the breakage of the fogged nuclei by positive holes (see, U.S. 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

I and 720,660; and Japanese Pat. Publication No.

A l-phenyl(substituted or unsubstituted)-3- amylamino-pyrazole coupler substituted by an msulfobenzoxy group at the 5-position is disclosed in the specification of U.S. Pat. No. 2,706,685.

However, the object of this U.S. Patent is to provide a coupler having an alkali-soluble group so that it can be dispersed as an aqueous solution thereof in a negative silver halide emulsion and further to provide a coupler having a high coupling activity. Accordingly, such a disclosure in the patent differs fundamentally from the objects of this invention.

Many methods are known for dispersing color couplers in hydrophilic colloids. According to one of those known methods, a coupler having in the coupler molecule a water-soluble group such as a sulfo group, a carboxyl group, a hydroxyl group or an amino group is incorporated in a silver halide emulsion in a micellar state as an aqueous solution or an alkali solution thereof. In another method, a coupler is solubilized in a surface active agent and then the coupler is incorporated in a silver halide emulsion. According to still another method, at least a part of an oil-soluble color coupler substantially insoluble in water (having a solubility in water of less than 1%) is dissolved in a high boiling plasticizer such as tricresyl phosphate, dibutyl phthalate, a biphenyl ether derivative, and oil (including fats) and then dispersed in a silver halide emulsion as fine particles using a surface active agent. By even another method, when an oil-soluble coupler itself is in an oily state or in a liquid state at high temperatures, the coupler is directly dispersed, as liquid, in a silver halide emulsion using a surface active agent. By another method a color coupler is dispersed physically in a silver halide emulsion as fine solid particles. According to an another method a'color coupler is dispersed in a silver halide emulsion together with a hydrophilic colloid utilizing the coaction between the coupler molecule and the colloid molecule. Any methods described above can be used in this invention but the third, fourth, and sixth methods as described above are particularly useful. 1

The color coupler precursor used in this invention is a coupler having a pyrazole nucleus substituted by an acyloxy group at the 5-position thereof and it may be represented by, for example, the following general formula:

wherein A represents a monocyclic aryl group, such as a phenyl group, a chlorophenyl group, a methylphenyl group, an ethylphenyl group, an ethoxyphenyl group, a

cyanophenyl group and a substituted derivative thereof wherein the further substituent may be a halogen atom such as chlorine and/or an alkyl group such as a methyl group; W represents an alkyl group, such as a methyl group, an ethyl group, a propyl group, a butyl group, a chloromethyl group, a methoxymethyl group, a methoxyethyl group, an ethoxyethyl group, a phenoxymethyl group, a benzyl group, and a substituted derivative thereof wherein the further substituent may be a halogen atom such as chlorine and/or an alkyl group such as a methyl group or an aryl group, such as a phenyl group, a chlorophenyl group, a bromophenyl group, a methoxyphenyl group, a nitrophenyl group, a tolyl group, a naphthyl group, a chloronaphthyl group, and a substituted derivative thereof wherein the further substituent may be a halogen atom such as chlorine and/or an alkyl group such as a methyl group; and Zv represents a diffusion resisting balasting group, preferably an acylamino group, a ureido group, or the like which are well known to one skilled in the art. The balasting group is preferably those having greater than 8 carbon atoms.

Now, the specific examples of the color coupler precursors used in this invention are given below although the color couplers are not limited to these compounds only.

who;

C iisHaicoNH Each of those acyloxypyrazoles may be prepared by condensing a triethylamine salt of the corresponding pyrazolone and an acid chloride. For example, Coupler (01) may be prepared by the following manner.

SYNTHESIS EXAMPLE 1 60 g of l-(2,4,6-trichlorophenyl )-3-( 3- hexadecaneamidobenzamido)-5-pyrazolone and g of triethylamine were added to 400 ml of acetonitrile and after dissolving the additives by heating, the solution prepared was cooled with ice, thereby colored 10 crystals were precipitated. By recovering the crystals thus precipitated by filtration and drying them, 65 g of the triethylamine salt of the pyrazolone was obtained.

The entire amount of the salt obtained above was dissolved in 350 ml of acetonitrile and after adding thereto 13 g of acetyl chloride, the resultant mixture was refluxed for 2 hours. When the mixture was, then, cooled with ice, colorless crystals were precipitated. When the crystals were recovered by filtration, washed with acetonitrile, and recrystallized quicl ly from 230 are? massif, 29 g (FC oupler C -Dhavinga melting point of 1 15 C was obtained. I

Other acyloxy pyrazoles used in this invention may also be prepared in a similar manner according to the method shown in the above Synthesis Example 1.

Comparison color couplersused in the comparison examples are as follows:

(7.5? ii'siil' o'oiiiii A For the silver'ha'lid'e emulsion in this invention, a gel atin protective colloid, in particular inert gelatin is advantageously used. In place of such gelatin, a partially inert gelatin derivative and hydrophilic synthetic polymers such as polyvinyl acrylate, polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl algina'te may also be used. The silver halide grains used in this invention are grains of silver salts composed of chloride ions, bromide ions, iodide ions, or a mixture of these ions. However, for the B-type emulsion it is preferable to use silver bromide or silver iodobromide. The electron acceptor or the halogen acceptor is preferably used in an amount of l X 10 mol to 5 X 10" mol per mole of the silver salt or salts.

The silver halide emulsion used in this invention may contain materials having known functions and used in conventional light sensitive materials, for example, a

stabilizer for fogged nuclei, such as a mercapto compound, a thion compound, a tetrazole derivative, and a tetrazaindene derivative; an improving agent for clearness, such as a stilbene compound and a triazine compound; a ultraviolet absorbing dye for improving COMPARISON EXPERIMENT A silver chlorobromide emulsion prepared in a conventional manner for the production of the A-type emulsion was placed in three pots each in an amount of 100 g and was heated to 40 C. Then, 20 cc of a 5 wt% ethyl acetate solution 5f the compoundt'c 'nwas' added to the first pot while stirring vigorously with ultrasonic waves. Further, 20 cc of a 5 wt% ethyl acetate solution of the comparison compound (A) was similarly added to the second pot. Also, 20 cc of a 5 wt% alkaline aqueous solution of the comparison compound (B) was added to the third pot and then the mixture in the third pot was neutralized (to the pH of 6.5) using an aqueous citric acid solution.

To each of the emulsions thus prepared were added 4 cc of a 2% aqueous solution of sodium dodecylbenzenesulfonate and 4 cc of a 2% aqueous solution of 2,4- dichloro-6-hydroxy-S-triazine. Then, the emulsion was immediately applied to a cellulose triacetate film so that the dry thickness was about 6 microns.

Each of the three kinds of samples was exposed through an optical wedge to light of a tungsten lamp of 2,854 K and then processed using following steps:

(I) Color Development 29.5C 6 min. (2) Stop Fixing 2 min. (3) Rinse 2 min. (4) Bleaching 2 min. (5) Rinse 2 min. (6) Hardening Fixing 4 min. (7) Rinse 4 min. (8) Stabilization 2 min. (9) Drying By measuring the densities of the strips thus obtained through a green filter, characteristic curves were obtained, the results of which are shown in Table 1.

Table 1 Coupler Photographic Properties No. Type- W Relative Minimum Emulsion Compound Amount Sensitivity Density (100g) l A-type (C-l) l g I 0.l4 2 (A) 28 0.32 (B) 0.65

' The relative sensitivity was less than 5 and thus an accurate measurement of the sensitivity was not obtained.

' The sensitivity at the density point of A of the maximum density.

From the results shown in Table I, it can be seen that .t sgqssnta saurl tprsqa sm. sed n this inxc r Compound (01). gave rise to excellent properties such as less fog and a remarkably high sensitivity in comparison with the known pyrazolone couplers (A) and (B).

The compositions of the processing baths used in the above processings were as follows:

Color Developing Solution Sodium Mctahorate 25.0 g Sodium Sulfite 2.0 g Hydroxylamine Sulfate 2.0 g Potassium Bromide 0.5 g o-Nitrobenzimidazole Nitrate 0.02 g Sodium Hydroxide 4.0 g Benzyl Alcohol 15.8 cc Diethylenc Glycol 20.0 cc N-Ethyl-N-B-(methancsulfoamidoJ-p-phcnylenediaminc 8.0 g Water added to make I liter (pH l().6)

Stop Fixing Solution Ammonium Thiosulfate v 120.0 g Sodium Metabisulflte 20.0 g Glacial Acetic Acid 10.0 g Water added to make 1 liter (pH 4.5)

Bleaching Solution Potassium Nitrate 25.0 g Potassium Ferricyanide 20.0 g Potassium Bromide 8.0 g Boric Acid 5.0 g Borax 2.5 g Water added to make 1 liter (pH 7.2)

Hardening Fixing Solution Ammonium Thiosulfate l20.0 g Sodium Sulfite 5.0 g Boric Acid 2.5 g Formalin (3540 percent) 40.0 cc Water added to make 1 liter (pH 9.5)

EXAMPLE 1 A silver iodobromide emulsion prepared in a conventional manner for the preparation of the B-type emulsion was placed in each pot in an amount of 1 Kg and melted at 40 C. Then, a electron acceptor or a mixture of an electron acceptor and a halogen acceptor as shown in Table 2 were added to the emulsion for adsorption on the silver halide grains. The emulsion was 7 then allowed to stand for about 20 minutes. Thereafter,

59912929. of smu sifissl. dispersion d qr d hereinafter, of the compounds (O1), (C-2), (C-3), (C-4), and (C-5) of this invention shown in Table 2 was added to the emulsion followed by stirring.

Then, 10 cc of a 2% aqueous solution of N tetradecyl-N,N-di-polyoxyethylene betaine and 10 cc of a 2% aqueous solution of 2,4-dichloro-6-hydroxy-S- triazine were added to the silver halide emulsion to provide a finished silver halide emulsion. The emulsion was applied to a transparent cellulose triacetate film and dried so that the dry thickness of the emulsion layer was about 6 microns.

The emulsified dispersion of the coupler precursor of this inv e n t ior i t 1sed above was prepared by the following manner. That is to say. 1 Kg of a 10 wt% aqueous solution of inert gelatin was heated to 60 C. Thereafter, cc of a 5% aqueous solution of sodium dodecylbenzene sulfonate was added to the emulsion. On the other hand, 0.15 mole of the coupler precursor was added to a mixture of 100 g of dibutyl phthalate and 50 cc of butyl acetate and the former was dissolved completely in the solvent mixture by heating. The solution thus prepared was added to the gelatin solution prepared above, dispersed immediately in the gelatin solution using a high speed rotary mixer and a ultrasonic vibrator, and after adding further 1 Kg of water to the dispersion followed by stirring, the mixture was set by cellent photographic properties such as a very high senrapid cooling. sitivity and less formation of fog in comparison with The photosensitive films prepared above were subconventional materials are obtained by using the ma jected to sensitometry according to the procedure as genta coupler precursor having a pyrazolone nucleus shown in the Comparison Experiment 1. The results of substituted with an acyloxy group at the 5-position thewhich are shown in Table 2. reof.

TABLE?" Sensitizing Dye Photographic Properties spectrogram No. Coupler Precursor Electron Acceptor Halogen Acceptor Relative Minimum Density (amount) Sensitivity -4 (C-l) (8-!) (0.4 millimole) None 100 0.12 FIG. 2 5 02 (S-l)(0.6 125 0.11 FIG. 3 6 (C-3) (s-2 0.4 400 0.12 FIG. 4 7 c4 s-3)(0.3 400 0.11 FIG, 5 s (05 s-4 0.4 250 0.11 FIG. 6 9 05) (8-1 04 s-5) 0.2 millimole) 175 0. 12 FIG. 7

2 The sensitivity at the sensity point of H2 of the maximum density. N W 1 The chemical structural formulae of the sensitizing dyes used in this example were as follows:

(s-1): Thep hotosensitive film coated thereon with the direct positive silver hallde photographic emulsion in accordance with the present invention can be prepared \N/ by the conventional procedure. Suitable support for the photosensitive film includescellulose esters such as S cellulose diacetate, cellulose triacetate, cellulose ace- A' N02 tate butyrate and the like, synthetic resin films such as CH=CH l polyethylene terephthalate, polystyrene, polycarbon- 3Q ate, polyethylene, polypropylene, polyvinyl'acetal films The thickness of the emulsion layer containing the magenta coupler precursor can range from 1 to 20 u. The amount of the color coupler can range from 2 to l/lOO mole per one mole of silver halide, preferably from 1 to 1/60 mole. Suitable amount of silver halide can range from 5 mg to 200 mg, preferably from 10 mg to 100 mg per 100 cm of the coating based on the 40 amount of silver.

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:

o N N 1. A color photographic material giving colored im- N02 ages by color developmentin a color developing solu- CH=CHCH= L tion containing a phenylenediamine as the color devel- ,t \N i and the like, glass, paper, a laminate of paper and a m a resin such as polyethylene, a metal plate and the like.

5 oping agent comprising a support having thereon at least one direct positive silver halide photographic H9430- emulsion layer, said silver halide emulsion layer containing silver halide grains in which the surface of said grains are chemically fogged and said silver halide emulsion layer containing a magenta color coupler precursor having a pyrazole nucleus substituted with an O acyloxy group at the 5-position of said pyrazole nucleus. Q CH CH CH 2. The color photographic material as set forth in claim 1, wherein said silver halide emulsion has the fol- (flmofksor 4313920114, OaHN (ozHm lowing characteristics:

Ha Ha g X D -A3.)

and

From the above descriptions, in particular the results 0 shown in Table l and Table 2, it can be seen that the Sb direct positive color photographic materials having exwherein D (b) is the minimum optical density of the silver halide emulsion coated on a test strip, subjected to a vacuum of below mmHg for more than 17 hours, exposed to a blue light through an optical wedge under said vacuum and developed, wherein D, (a) is the maximum optical density of the silver halide emulsion coated on a test strip, ex-

posed to a blue light through an optical wedge and wherein A represents a monocyclic aryl group, W rep resents an alkyl group or an aryl group, and Z represents a diffusion resisting acylamino group or a diffusion resisting ureido group.

4. The color photographic material as set forth in claim 1, wherein said color coupler precursor is a compound represented by the formula wherein A represents a monocyclic aryl group, W represents an alkyl group or an aryl group, and Z represents a diffusion resisting acylarnino group or a diffusion resisting ureido group.

5. The color photographic material as set forth in claim 1, wherein said silver halide grains of said silver halide photographic emulsion have adsorbed thereon an electron acceptor having at least one of a sulfo group, a carboxyl group, or a phosphate group.

6. The color photographic material as set forth in claim 1, wherein the silver halide grains of said silver halide photographic emulsion have adsorbed thereon an electron acceptor having at least one of a sulfo group, a carboxyl group, or a phosphate group and a halogen acceptor having at least one of a sulfo group or a carboxyl group.

7. The color photographic material as set forth in claim 1, wherein said silver halide grains are chemically fogged using stannous chloride, sodium borohydride, cuprous chloride, hydrazine, a hydrazine derivative, formalin, thiourea dioxide, a polyamino' compound, an amine borane, or methyl dichlorosilane.

8. The color photographic material of claim l, wherein said emulsion is a gelatin emulsion and wherein saidsilver halide is silver chloride, silver bro-- mide, silver iodide, or mixtures thereof.

9. The color photographic material as set forth in claim 6, wherein said electron acceptor and said halogen acceptor are present at a level of from 1 X l0 to 5 X 10 mole per mole of silver halide.

10. A color photographic element comprising a support having thereon at least one layer of the color photographic material of claim 1.

Claims

2. The color photographic material as set forth in claim 1, wherein said silver halide emulsion has the following characteristics: 1. Dmin (b) 0.3 X Dmax (a) and 2. Sb < or = 0.65 X Sa wherein Dmin (b) is the minimum optical density of the silver halide emulsion coated on a test strip, subjected to a vacuum of below 10 4 mmHg for more than 17 hours, exposed to a blue light through an optical wedge under said vacuum and developed, wherein Dmax (a) is the maximum optical density of the silver halide emulsion coated on a test strip, exposed to a blue light through an optical wedge and at normal pressures and developed, wherein Sa is the sensitivity of the silver halide emulsion at said maximum optical density obtained at normal pressures, wherein Sb is the sensitivity of the silver halide emulsion at 1/2 of the maximum optical density of the silver halide emulsion evaluated at under said vacuum.
3. The color photographic material as set forth in claim 1, wherein said color coupler precursor is a compound represented by the formula
4. The color photographic material as set forth in claim 1, wherein said color coupler precursor is a compound represented by the formula
5. The color photographic material as set forth in claim 1, wherein said silver halide grains of said silver halide photographic emulsion have adsorbed thereon an electron acceptor having at least one of a sulfo group, a carboxyl group, or a phosphate group.
6. The color photographic material as set forth in claim 1, wherein the silver halide grains of said silver halide photographic emulsion have adsorbed thereon an electron acceptor having at least one of a sulfo group, a carboxyl group, or a phosphate group and a halogen acceptor having at least one of a sulfo group or a carboxyl group.
7. The color photographic material as set forth in claim 1, wherein said silver halide grains are chemically fogged using stannous chloride, sodium borohydride, cuprous chloride, hydrazine, a hydrazine derivative, formalin, thiourea dioxide, a polyamino compound, an amine borane, or methyl dichlorosilane.
8. The color photographic material of claim 1, wherein said emulsion is a gelatin emulsion and wherein said silver halide is silver chloride, silver bromide, silver iodide, or mixtures thereof.
9. The color photographic material as set forth in claim 6, wherein said electron acceptor and said halogen acceptor are present at a level of from 1 X 10 6 to 5 X 10 3 mole per mole of silver halide.
10. A color photographic element comprising a support having thereon at least one layer of the color photographic material of claim 1.