US3297447A - Stabilization of synergistically sensitized photographic systems - Google Patents

Description

United States Patent 3,297,447 STABILIZATION OF SYNERGISTICALLY SENSI- TIZED PHOTOGRAPHIC SYSTEMS Patricia A. McVeigh, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey N Drawing. Filed Sept. 9, 1965, Ser. No. 486,235 22 Claims. (Cl. 96-109) This application is a continuationdn-part application of my copending application Serial No. 384,528, filed July 22, 1964, now abandoned. V

This invention relates to photography and more particularly to the stabilization of photographic systems sensitized with a combination of a noble metal sensitizer, e.g., a gold salt, and a labile selenium sensitizer.

It is known that photographic systems such as silver halide systems, particularly gelatino silver halide emulsions, can be sensitized chemically with a combination of a noble metal sensitizer, e.g. a gold salt, and a labile sulfur compound. It is, furthermore, known that photographic silver halide emulsions can be sensitized with labile selenium compounds. It has been generally thought that he sensitization of such emulsions by means of labile selenium requires a somewhat larger amount of sensitizer than when a sulfur sensitizer is employed.

In copending applications Serial No. 343,456, filed February 10, 1964, now abandoned, and Serial No. 468,972, filed July 1, 1965, of Joseph S. Dunn, it is shown that small amounts of selenium sensitizers can be employed in combination with noble metal sensitizers to produce effects which cannotbe obtained with a combination of sulfur sensitizer and noble metal sensitizer, even where a considerably larger amount of sulfur sensitizer than selenium sensitizer is employed. Since the prior art tends to treat selenium and sulfur sensitizers as equivalents, this behavior was not anticipated.

While the Dunn photographic systems referred to above do produce marked increases in speed, as compared with gold-and sulfur-sensitizer photographic systems, they introduce a problem of stability, which can be an important factor in some instances.

It is, therefore, an object of my invention to provide new stabilized photographic systems sensitized with a combination of a labile selenium sensitizer and a noble metal sensitizer for increasing the speed synergistically of such photographic systems. It is another object of this invention to provide new stabilized synergistically sensitized silver halide emulsions without adversely affecting the speed of such emulsions. Other objects will become apparent from a consideration of the following description and examples.

I have now found that photographic systems sensitized with a combination of a noble metal and labile selenium can be effectively stabilized by including in the photographic system a labile sulfur compound. In my invention, these labile sulfur compounds do not cause any phenomenal increase in the speed of the emulsions but they do cause a very significant increase in the stability of such sensitized photographic systems. While the invention described in the aforementioned Dunn applications is outstanding in providing marked increases in speed, as compared with known methods of chemical sensitization, the method of Dunn sometimes leads to an increase in fog. While there are certain means described by Dunn for controlling fog, I have found that the labile sulfur compounds of my invention provide a particularly efficacious means of controlling fog without deleteriously affecting the speed of the stabilized photographic system. In some instances there may also be a small increase in speed as a consequence of the addition of the labile sulfur compound.

Particularly useful labile sulfur compounds for my invention include the well-known class of compounds which have been previously identified as labile sulfur sensitizers. These include the water-soluble thiosulfa-tes such as alkali metal thiosulfates including sodium and potassium thiosulfates, as well as ammonium thiosulfate; thioureas such as thiourea, allylisothiourea, diacetylthiourea; thiosemicarbazide; thiocarbamates such as isopropylthiocarbamate; and the like labile sulfur compounds. Other labile sulfur compounds useful in my invention are described in an article by T. H. James and W. Vanselow in J. Phot. Sci., vol. 1 (1953), page 133, as well as in an article by A Hautot and H. Sauvenier in Sci. Ind. Phot., vol. 27 (1957), No.1.

The amount of labile sulfur compound used in my invention can vary considerably depending upon the particular sensitized photographic system employed, finishing conditions, including temperature and time of digestion and ripening, etc. In general, I have found that the unique stabilizing effect of labile sulfur compounds can be accomplished at a somewhat lower concentration than might be required in their use as sulfur sensitizers. With reference to silver halide photographic systems, particularlyuseful results have been obtained at concentrations of about 0.1 to 10 mg. per mole of silver halide. Larger or smaller quantities can be employed without adversely affecting the sensitometric properties of the photographic system. The labile sulfur compounds are efficaciously added to be present during the chemical sensitization of the photographic system.

The selenium sensitizers useful in my invention include a wide variety of labile selenium sensitizers, many having been previously suggested for use alone in sensitizing photographic silver halide emulsions. Suitable selenium addenda are disclosed in Sheppard et al. US. Patent 1,623,- 499, issued April 5, 1927, .as well as Sheppard US. Patents 1,574,944, issued March 2, 1926, and 1,602,592, issued October 12, 1926. The labile selenium sensitizers of my invention which have been found to be particularly useful are organic selenium compounds wherein the selenium atom is doubly bonded to a carbon atom of the organic compound through a covalent linkage. Thus, especially useful compounds include selenoamides, selenoketones (especially ketones having an alkyl radical attached to the L J=Se l moiety), selenocarboxylic acids and esters, etc. Useful groups of selenium sensitizers include aliphatic selenoureas wherein the aliphatic radical is, for example, an alkyl radical such as methyl, ethyl, propyl, isopropyl, butyl, heXyl, octyl, etc. Such selenoureas have at least one hydrogen atom attached to the nitrogen atom thereof, thus making possible the formation of an enol tautomer. Also useful in my invention are analogous selenoureas containing one or more aromatic radicals, such as phenyl, tolyl, etc., or heterocyclic radicals, such as benzothiazolyl,

syridyl, etc., and aliphatic isoselenocyanates. Other useful labile selenium sensitizers are selenophosphates such as tri-alkyl and tri-aryl selenophosphates. It has also been found that colloidal selenium itself is a useful sensitizer.

Illustrative addenda suitable for furnishing the labile selenium moiety in the stabilized photographic systems of the invention include:

colloidal selenium, selenoacetone, selenoacetophenone, tetramethylselenourea,

N- (fi-carboxyethyl) -N,N'-dimethylselenourea, selenoacetamide, diethylselenide, triphenylphosphine selenide, tri-p-tolylselenophosphate, tri-n-butylselenophosphate, 2-selenoproponic acid, 3-selenobutyric acid, methyl-3-selenobutyrate, allyl isoselenocyanate, and dioctylselenourea.

The concentration of selenium sensitizer can be varied considerably depending upon the particular selenium addendum employed (some sensitizers being more efficacious than others), the nature of the photographic system, the amount and chemical nature of the noble metal sensitizer, etc. In silver halide systems, for example, I have found that useful results can be obtained using amounts as small as 0.05 mg. of selenum sensitizer per mole of silver halide although considerably larger amounts can also be employed, such as 5.0 mg. or more per mole of silver halide.

The term labile as used herein has the meaning well understood by those skilled in the art of photography, i.e., a material which yields a silver salenide or sulfide that is insoluble in water at room temperature (20 C.) upon addition to an aqueous silver nitrate solution. For example, selenourea is a labile selenium compound, since silver selenide precipitates when selenourea is added to an aqueous silver nitrate solution. Similarly, colloidal selenium precipitates silver selenide upon addition to aqueous silver nitrate and is, therefore, a labile selenium addendum or sensi-tizer of invention. Likewise, sodium thiosulfate is a labile sulfur compound as silver sulfide precipitates when an aqueous sodium thiosulfate solution is added to an aqueous silver nitrate solution.

The noble metal sensitizers useful in the photographic systems stabilized in accordance with my invention include the well-known gold sensitizers which have been previously recognized as useful in the photographic art and found to be outstanding intheir sensitizing action, including water-soluble and water-insoluble organic and inorganic gold compounds and salts, although other noble metal sensitizers can be used, including palladium, platinum, etc., sensitizers such as are disclosed in Smith et al., U.S. Patent 2,448,060, issued August 31, 1948. Typical suitable gold sensitizers are described in Waller et al., U.S. Patent 2,399,083, issued April 23, 1946, and Damschroder et al., U.S. Patent 2,642,361, issued June 16, 1953.

Illustrative addenda suitable for furnishing the noble metal moiety in the sensitizer combinations of the invention include:

gold chloride,

potassium aurate,

potassium auriaurite,

potassium auricyanide,

potassium aurithiocyanate,

gold sulfide,

gold selenide,

gold iodide,

potassium chloroaurate, ethylenediamine-bis-gold chloride,

4 ammonium chloroplatinite, i.e., (NH PtCl ammonium chloropalladate, i.e., (NI-I PdCl and organic gold sensitizers having the formulas:

CH: C

II. S\

I C-SAu N N C2 H5 C1 III. 0

N zHa C=GHCH=G (LL s Au i S P3 O1 N om. C=C y: SM N S 12115 CCH3 C2115 AllCl;

VI. S H H2 CCH=CHN OH: (I C N\ Hz H2 Cfia AuCl; VII. f

@ N O $2115 (lg H5 AuCh VIII. S i S\ C=CH-C N N i 'zHa C2 Ha U C=CH 1 \N/ N CzH A1101: $2155 AuCh X. s s

/ I C=CHC I 2 5 C2115 The quantity of noble metal sensitizer useful in sensitizing the photographic systems of the invention can likewise be varied as in the case of selenium sensitizer. I have found, for example, that amounts varying from about 0.1 to 5.0 mg. of gold sensitizer per mole of silver halide are quite satisfactory.

The noble metal moiety and the labile selenium moiety used in sensitizing the photographic systems stabilized in accordance with the invention are more generally added to the photographic system as separate entities, although such is not necessary.

It has been found that particularly useful results are obtained in prepared noble metal and selenium sensitizing combinations in cases where as water-soluble thiocyanate compound is present. Typical thiocyanates include sodium thiocyanate, potassium thiocyanate, ammonium thiocyanate, etc. Other water-soluble thiocyanates can be employed to equal advantage. The amount of thiocyanate compound used can likewise be varied, depending upon the particular system being sensitized, relative amounts of selenium and noble metal sensitizers,

etc.

The sensitizing addenda used in sensitizing the photographic systems stabilized in accordance with the invention can be added in a variety of ways to photographic systems and at various stages in the preparation of such. In general, with respect to silver halide emulsions, such addenda can be added with useful effects at the completion of the Ostwald ripening and prior to one or more of the final digestion operations. The sensitizing addenda of the invention are preferably added to silver halide emulsions after the silver halide grains are substantially in their final size and shape. The addenda can be added in the form of their aqueous solutions, Where they are soluble in water, or in an innocuous organic solvent where the sensitizer does not have suflicient solubility in water to be used in the form of an aqueous solution. Particulanly useful organic solvents include ethanol, methanol, pyridine, acetone, dioxane, etc. That is, organic solvents which have a rather high degree of polarity are preferred. Where it is desired to add the sensitizing addenda in some other form than a solution, this procedure is also possible, especially where the sensitizer is available in the form of a colloidal suspension. In some cases, it is possible to add the sensitizers suspended in an organic solvent which forms very small suspended particles or globules in the photographic emulsion similar to the type of colloidal particle produced in preparing coupler dispersions. Dispersing media useful for this purpose include tricresyl phosphate, dibutyl phthalate, triphenyl phosphate, etc. The order of addition of sensitizers and stabilizers to the emulsion can be varied. For example, the sensitizers (part or all) can be added before or after the sulfur stabilizer. Especially useful results are obtained where all addenda are added prior to the final digestion.

In the preparation of dispersions of light-sensitive materials such as silver halide and the like, there can be employed as the dispersing agent gelatin or some other colloidal material, such as colloidal albumin, a cellulose derivative or a synthetic resin, for instance, a polyvinyl compound. Hydrophilic colloids which can be used are polyvinyl alcohol or a hydrolyzed polyvinyl acetate as described in Lowe U.S. Patent 2,286,215, issued June 16, 1942; a far hydrolyzed cellulose ester such as cellulose acetate hydrolyzed to an acetyl content of 19 to 26% as described in U.S. Patent 2,327,808, of Lowe and Clark,

issued August 24, 1943; a water-soluble ethanolamine cellulose acetate as described in Yutzy U.S. Patent 2,322,- 085, issued June 15, 1943; a polyacrylamide or an imidized polyacrylamide as described in Lowe, Minsk and Kenyon U.S. Patent 2,541,474, issued February 13, 1951; copolymers (alone or in admixture with another colloid, e.g., gelatin) of an alkyl acrylate, e.g., ethyl or butyl acrylate, and acrylic acid, such as those described in Houck et al. U.S. Patent 3,062,674 issued November 6, 1962 and Houck et al. U.S. application Serial No. 139,- 313, filed September 19, 1961; zein as described in Lowe U.S. Patent 2,563,791, issued August 7, 1951; a vinyl alcohol polymer containing urethane carboxylic acid groups of the type described in Unruh and Smith U.S. Patent 2,768,154, issued October 23, 1956; or containing cyanoacetyl groups such as the vinyl alcohol-vinyl cyanoacetate copolymer as described in Unruh, Smith and Priest U.S. Patent 2,808,331, issued October 1, 1957; or a polymeric material which results from polymerizing a protein or a saturated acylated protein with a monomer having a vinyl group as described in U.S. Patent 2,852,- 382, of Illingsworth, Dann and Gates, iissued September 16, 1958. Mixtures of such dispersing agents in a wide range of proportions can be utilized, typical of such mixtures being mixtures of gelatin and an acrylate-acrylic acid copolymer.

The loss of density sometimes occurring when a photographic emulsion is dried can be prevented or substantially reduced by incorporating in the gelatin silver halide emulsions of my invention a water-soluble, gelatin-compatible vinyl monomer. Only a small amount of such an addendum is generally required, and frequently amounts as small as about 5%, based on total solids in the emulsion are useful, although it is obvious that much larger amounts, such as about can be employed in certain types of emulsions. Typical polymers which can be used in combination with gelatin to prevent loss of density and thereby increase the covering power in the processed, dried layer include the polyvinyl lactams, such as polyvinylpyrrolidone, as well as other polyvinyl lactams described in Du Pont British Patent 867,899, published May 10, 1961. Other useful polymers include polyacrylamide types, such as polyacrylamide itself, or copolymers of acrylic amide with other ethylenically-unsaturated monomers, including acrylic acid, methacrylic acid, methacylamide, acrylonitrile, methyl acrylate, butyl acrylate, methyl methacrylate, butyl methacrylate, or mixtures of these monomers. Other colloids useful in preventing or inhibiting such density losses include natural gums, salicylic acid condensates, etc.

I have found that the speed of noble metal-selenium sensitized emulsions stabilized with a labile sulfur compound can be further increased by including in the emulsions a variety of hydrophilic colloids, such as carboxymethyl .protein of the type described in U.S. Patent 3,011,- 890, issued December 5, 1961. Polysaccharides of the type described in Canadian Patent 635,206 can also be used to further increase the speed of my emulsions.

Such emulsions can contain speed-increasing compounds of the quaternary ammonium type of CarrollU.S. Patent 2,271,623, issued February 3, 1942; Carroll and Allen U.S. Patent 2,288,226, issued June 30, 1942; and Carroll and Spence U.S. Patent 2,334,864, issued November 23, 1943; or the polyethylene glycol type of Carroll and Beach U.S. Patent 2,708,162, issued May 10, 1955; or the quaternary ammonium salts and polyethylene glycols of Piper U.S. Patent 2,886,437, issued May 12, 1959; as well as the thiopolymers of Graham and Sagal U.S. Patent 3,046,129, issued July 24, 1962, and the Dann and Chechak U.S. Patent 3,046,134, issued July 24, 1962. Prequently, useful effects can be obtained by adding the aforementioned speed-increasing compounds to the photographic developer solutions instead of, or in addition to, the photographic emulsions.

The photographic systems stabilized according to the technique of my invention are especially useful in the preparation of integral screen X-ray materials. Such X-ray materials have the advantage of convenience of handling and improved sharpness, inasmuch as they can be prepared using a single silver halide emulsion coated on but one side of the photographic support, as compared with conventional X-ray materials which have a silver halide emulsion layer coated on each side of the support (i.e., duplitized material). Since an opaque screen is employed in integral X-ray materials, the possibility of using an emulsion on only one side of the support is most desirable, and by using the novel emulsions of my invention, it is possible to use silver halide emulsion having finer grain to reach a given speed. This results in higher contrast for such a material, since finer grain emulsions inherently produce higher contrast. Thus, for the same grain size, it is possible to obtain higher speeds with the selenium-gold sensitized emulsions of my invention. An integral screen X-ray material using the novel emulsions of my invention can have the layer arrangement shown in French Patent 1,324,023, issued March 4, 1963. In such an arrangement the intensifying screen is located on the side opposite to the emulsion so that the screen remains with the positive after stripping. Other arrangements which can be used in the preparation of integral screen materials are described in Blake et al. US. Patent 2,887,379, issued May 19, 1959 (col. 8, lines 4 to 21). In a typical integral screen X-ray material of my invention, a conventional support is coated in succession with an intensifying screen, receiving layer, silver halide emulsion layer containing my novel combination of selenium and noble metal sensitizers, and if desired, a thin protective layer of gelatin (which can be omitted, if desired). Other arrangements will become apparent to those skilled in the art.

In addition to being useful in X-ray and other nonoptically sensitized systems, the stabilized photographic systems of the invention can also be used in orthochromatic, panchromatic, and infrared sensitive systems. Various silver salts can be used as the sensitive salt in sensitized silver halide systems stabilized in accordance with the invention such as silver bromide, silver iodide, silver chloride, or mixed silver halides, such as silver chlorobromide or silver bromoiodide. The present photographic systems can be used for color photography, for example, in silver halide emulsions containing color-forming couplers or emulsions to be developed by solutions containing couplers or other color-generating materials, emulsions of the mixed-packet type, such as described in Godowsky US. Patent 2,698,794, issued January 4, 1955; in silver dye-bleach systems; and emulsions of the mixedgrain type, such as described in Carroll and Hanson US. Patent 2,592,243, issued April 8, 1952.

Typical color-forming compounds or couplers which are useful in color photography, according to our invention, include the following:

COUPLERS PRODUCING CYAN IMAGES 5-(p-amylphenoxybenzenesulfonamino) -1-naphthol 5 (N-benzyl-N-naphthalenesulfonamino) -1 -naphtho1 5-(n-benzyl-N-n-valerylamino) -1-naphthol S-caproylamino-1-naphthol 2-chloro-5- (N-n-valeryl-N-p-isoproylbenzylamino 1-naphthol-2-carboXylic-a-naphthalide 1-naphthol-5-sulfo-cyclohexylamide 5 -phenoxyacetaminol-naphthol S-B-phenylpropionylaminol-naphthol Monochlor-5- (N-y-phenylpropyl-N-p-sec.-amylbenzoylamino)-l-naphthol Z-acetylamino-5-methylphenol .2-benzoylamino-3,S-dimethylphenol Z-oz (p-tert. amylphenoxy) n-butyrylamino-S-methylphenol 6 {v-{4- ['y- 2,4-di-tert. amylphenoxy butyramido] phenoxy} acetamido}-2,4-dichloro-3 -methylphenol l-hydroxy-Z- 5- 2,4-di-tert. amylphenoxy) -n-butyl] naphthamide Z-cc (p-tert. amylphenoxy) -n-butyrylamino-4-chloro- S-methylphenol 2- p-tert. amylphenoxy-p-benzoyl) amino-4-chloro- S-methylphenol 2- 4-tert. amyl-3 -phenoxybenzoylamino -3,5-dimethyll-phenol 2-phenylacetylamino-4-chloro-S-methylphenol 2-benzoylamino-4-chloro-5-methylphenol 2-anilinoacetylamino-4-chloro-5-methylphenol 2-{4'- [a- 4-tert. amylphenoxy -n-butyrylamino] benzoylamino}-4-chloro-5-methylphenol 2- 4-,3 (4-tert. amylphenoxy benzoylamino] benzoylamino-4-chloro-5 -methylphenol 2-p-nitrobenzoylamino-4-chloro-5-methylphenol 2-m-aminobenzoyl-4-ch1oro-5-methylphenol 2-acetarnino-4-chloro-5 -metl1ylphenol 2 (4-sec. amylbenzamino) -4-chloro-5-methylphenol 2 (4-n-amyloxybenzamino -4-chloro-5-methylphenol 2 (4-phenoxybenzoylamino phenol 2 (4"-tert. amyl-3 '-phenoxybenzoylamino phenol 2- oz- (4-tert. butylphenoxy) propionylamino] phenol 2- u- (4'-tert. amyl phenoxypropionylamino] phenol 2- [N-methyl-N- (4"-tert. amyl-3 phenoxybenzoylamino) phenol 2- (4"-tert. amyl-3 '-phenoxybenzoylamino -3-methyll-phenol 2- (4"-tert. amyl-3 '-phenoxybenzoylamino -6-methyll-phenol 2- 4"-tert. amyl-3 '-phenoxybenzoylamino -3,6-dimethylphenol 2,6-di (4-tert. amyl-3 '-phenoxybenzoylamino l-phenol Z-oc- (4'-tert. amylphenoxy) butyrylaminol-phenol 2 (4-tert. amyl-3 -phenoxybenzoylamino -3,5-dimethyll-phenol 2- a- (4'-tert. amylphenoxy -n-butyrylamino] -5-methy1- l-phenol 2 (4-tert. amyl-3 '-phenoxybenzoylamino -4-cl1lorol-phenol 3- a- (4-tert. amylphenoxy -n-butylrylamino] -6-chlorophenol 3- (4-tert. amyl-3 -phenoxybenzoylamino phenol 2- oz- (4-tert. amylphenoxy) -n-butyrylan1ino] -6-chlorophenol 3- Ot- (4'-tert. amylphenoxy -n-butyrylamino] -4-chlorophenol 3 06- (4-tert. amylphenoxy -n-butyrylamino] -5-chlorophenol 3 a- (4-tert. amylphenoxy) -n-butyrylamino] -2-chlorophenol Z-nc- (4-tert. amylphenoxybutyrylamino) -5-chlorophenol 2- (4"-tert. amyl-3 '-phenoxybenzoylamino -3-chlorophenol 5-benzene sulfonamino-l-naphthol 2,4-dichloro-5-benzenesulfonaminol-naphthol 2,4-dichloro-5- (p-toluenesulfonamino -l -naphthol 5-(1,2,3,4-tetrahydronaphthalene-6-sulfamino-1-naphthol 2,4-dichloro-5- (4'-bromodiphenyl-4-sulfon amino l-naphthol 5 quinoline-S -sulfamino -1-naphthol Any of the acylaminophenol couplers disclosed in Salminen and Weissberger US. Patent 2,423,730, dated July 8, 1947, can be used as couplers for the cyan image,

etc.

COUPLERS PRODUCING MAGENTA IMAGES l-p-sec. amylphenyl-3-n-amyl-5-pyrazolone 2-cyanoacetyl-5- (p-sec. amylbenzoylamino) coumarone 2-cyanoacetylcoumarone-5- (n-amyl-p-sec. amylsulfanilide) Z-cyanoacetylcoumarone-S- (N-n-amyl-p-tert. amylsulfanilide) 2-cyanoacetylcoumarone-5-sulfon-N-n-buty1anilide Z-cyanoacetyl-S-benzoylamino-coumarone Z-cyanoacetylcoumarone--sulfondimethylamide Z-cyanoacetylcoumarone-S-sulfon-N-methylanilide Z-cyanoacetylnaphthalene sulfon-N-methylanilide 2-cyanoacetylcoumarone-5- (N'y-phenylproyl -p-tert.

amylsulfonanilide l-p-laurylphenyl-3 -methyl-5-pyrazolone 1-B-naphthyl-3 -amyl-5-pyrazolone l-p-nitrophenyl-3-n-amyl-5-pyrazolone 1-p-phenoxyphenyl-3-n-amyl 5-pyrazolone 1-phenyl-3 -n-amyl-5-pyrazolone 1,4-phenylene bis-3-( l-phenyl-S-pyrazolone) 1-phenyl-3-acety1amino-S-pyrazolone 1-phenyl-3-propionylamino-S-pyrazolone 1-phenyl-3-n-valerylamino-S-pyrazolone l-phenyl-3-chloroacetylamino-S-pyrazolone 1-phenyl-3-dichloroacetylamino-5-pyrazolone 1-phenyl-3-benzoylamino-S-pyrazolone 1-phenyl-3- (m-aminobenzoyl) amino-S-pyrazolone 1-phenyl-3- (p-sec. amylbenzoylamino -5-pyrazolone l-phenyl-3-diamylbenzoylamino-5-pyrazolone 1-phenyl-3-fi-naphthoylamino-S-pyrazolone 1-phenyl-3 -phenylcarb amylamino-S-pyrazolone 1-phenyl-3 -pa1mitylamino-S-pyrazolorie 1-phenyl-3-benzenesulfony1amino-5 -pyrazolone 1- (p-phenoxyphenyl) -3- (p-tert. amyloxybenzoyl amino- S-pyrazolone 1- 2,4,6'-tribromophenyl -3-benzamido-5-pyrazolone 1-(2.,4',6'-trichlorophenyl) -3-benzamido-5-pyrazolone 1- (2,4,6'-trichlorophenyl -3 -phenylacetamido- 5-pyrazolone 1- 2,4',6'-tribromophenyl) -3 -phenylacetamido- 5 -pyrazolone 1- (2,4-dichlorophenyl) -3 [3 (2"',4"'-di-tert. amylphenoxyacetamido benzamido] -5-pyrazolone 1- (2',4',6-trichlorophenyl -3- 3-(2"',4'-di-tert. amylphenoxy-acetamido)benzamido1-5-pyrazolone 1- 2',4',6'-tr1brornophenyl -3- 3"- 2",4"-di-tert.

amylphenoxy-acetamido )benzamido] -5-pyrazolone l-2,4',6-trichlorophenyl) -3- [3- (2',4"'-di-tert. amylphenoxy) -propionamido] -5-pyrazolone 1- (2',4,6-tribromophenyl) -3- [18- (2',4'-di-te1't. amylphenoxy) -propionamido] -5-pyrazolone 1- (2,5 '-dichloro) -3- 3"- (4"-tert. amylphenoxy) benzamido1-S-pyrazolone 1- (2',4,6-tribromophenyl) -3- [3 (4"'-tert. amylphenoXy) benzamido] -5 -pyrazolone l-(2',5-dichlorophenyl) -3- [3 2",4"'-di-tert. amylphenoxyacetamido benzamido] -5-pyrazolone COUPLERS PRODUCING YELLOW IMAGES N-amyl-p-benzoylacetaminobenzenesulfonate N-(4-anisoy1acetaminobenzenesulfonyl) -N-benzyl-mtoluidine N- (4-benz0y1acetaminobenzenesulfonyl) -N-benzyl-mtoluidine N-(4-benzoylacetaminobenzenesulfonyl) -N-n-amy1-ptoluidine N- (4-benzoylacetaminobenzenesulionyl -N-benzylaniline w- (p-benzoylbenzoyl) acetanilide w-benzoylacet-2,S-dichloroanilide w-benzoyl-p-sec. amylacetanilide N,N'-di(w-benzoylacetyl -p-phenylenediamine N,N-di- (acetoacetamino) diphenyl oc{ 3- [a- 2,4-di-tert.-amylphen0xy) butyramido] benzoyl}-2-methoxyacetanilide a-{3- a- 2,4-di-tert.-amylphenoxy) acetamido] benzoyl}-2-methoxyacetanilide 4,4-diacetoacetamino -3,3 -dimethyldiphenyl p,p'-diacetoacetamino) diphenylmethane ethyl-p-benz0ylacetaminobenzenesulfonate Nonyl-p-benzoylacetaminobenzenesulfonate N-phenyl-N- (p-acetoacetaminophenyl urea n-propyl-p-benzoylacetaminobenzensulfonate acetoacetpiperidine w-benzoylacetpiperidide N (w-benzoylacetyl 1 ,2,3 ,4-tetrahydroquinoline N (w-benzoylacetyl) morpholine Photographic emulsions of the invention intended for use in color photography in systems wherein a dye (e.g., dye-bleach process) or the color-forming components are incorporated in the emulsions themselves, it is to be understood that these bleachable dyes or color-forming components can be incorporated in the emulsions according to any of the methods well known to those skilled in the art of photography. Since it is desired that the color-forming -components or couplers not wander from the layers in which they are incorporated, couplers which do have wandering tendencies can be employed in a useful manner according to the technique described in Jelley and Vittum US. Patent 2,322,027, issued June 15, 1943. This method comprises adding the color coupler to a water-immiscible crystalloidal solvent, such as tr icresyl phosphate or dibutyl phthalate and adding the solution to an aqueous emulsion. Where the couplers are characterized by inherent non-wandering characteristics due to the presence in the coupler molecules of a fatty type radical (e.g., l-(2,4,6-trichlorophenyl)-3-n-pentadecyl-5- pyrazolone; 1 phenyl 3 n-pentadecyl-4-(l-phenyl-S- tetrazolylthio) 5 pyrazolone; 1-phenyl-3-(3,5-disulfobenzamido) 4 (2-hydroXy-4-n-pentadecylphenylazo)-5- pyrazolone dipotassium salt, etc.), the coupler can be incorporated in the emulsion simply by dissolving it in a convenient organic solvent which does not have any deleterious effect upon the emulsion. Of course, the nature of the solvent will vary depending upon the solubility characteristics of the particular coupler. In general, solvents, such as pyridine, triethanolamine, ethyl alcohol, etc., can be employed for this purpose.

When used in the preparation of photographic systerns such as silver halide systems intended for color photography, such systems can be optically sensitized with cyanine and merocyanine dyes, such as those described in Brooker U.S. Patents 1,846,301, issued February 23, 1932; 1,846,302, issued February 23, 1932, and. 1,942,854, issued January 9, 1934; White U.S. Patent 1,990,507, issued February 12, 1935; Brooker and White U.S. Patents 2,112,140, issued March 22, 1938; 2,165,338, issued July 11, 1939; 2,493,747, issued January 10, 1950, and 2,739,964, issued March 27, 1956; Brooker and Keyes U.S. Patent 2,493,748, issued January 10, 1950; Sprague U.S. Patents 2,503,776, issued April 11, 1950, and 2,519,001, issued August 15, 1950; Heseltine and Brooker U.S. Patent 2,666,761, issued January 19, 1954; Heseltine U.S. Patent 2,734,900, issued February 14, 1956; Van Lare U.S. Patent 2,739,149, issued March 20, 1956; and Kodak Limited British Patent 450,958, accepted July 15, 1936.

The present photographic systems intended can also be used in diffusion transfer processes which, for example, utilize undeveloped silver halide in non-image areas of the negative to form a positive by dissolving the undeveloped silver halide and precipitating it on a receiving layer in close proximity to the original silver halide emulsion layer. Such processes are described in Rott U.S. Patent 2,352,014, issued June 20, 1944, and Land U.S. Patents 2,584,029, issued January 29, 1952; 2,698,236, issued December 28, 1954; 2,543,181, issued February 27, 1951, and 2,698,245, issued December 28, 1954; and Yackel et al. U.S. Patent 3,020,155, issued February 6, 1962. My photographic systems can be advantageously used in diflusion transfer systems utilized for document copying, and in those wherein a silver halide emulsion layer is coated adjacent to a fogged silver halide emulsion layer or a layer containing silver precipitating nuclei, such as nickel sulfide. The sensitive emulsion, following development, is then washed off, leaving the positive image in the light-insensitive layer containing the diffused silver image.

The present photographic systems can also be used in color transfer processes which utilize the diffusion transfer of an imagewise distribution of developer, coupler or dye, from a light-sensitive layer to a second layer, while the two layers are in close proximity to one another. Color processes of this type are described in Land U.S. Patents 2,559,643, issued July 10, 1951, and 2,698,798, issued January 4, 1955; Land and Rogers Belgian Patents 554,933 and 554,934, granted August 12, 1957; International Polaroid Belgian Patents 554,212, granted July 16, 1957, and 554,935, granted August 12, 1957; Yutzy U.S. Patent 2,756,142, granted July 24, 1956, and Whitmore and Mader Canadian Patent 602,607, issued August 30, 1960. The sensitizing combinations are compatible with a wide variety of dye-developer combinations, including anthraquinone dye developers, such as 4-[1,5'- bis (2",5"-dihydroxyphenyl) 3' pentyl] amino 1- hydroxyanthraquinone, or azo dye developers, such as 2,4 bis (2,5 dimethoxy 3' [2"-(2",5-dihydroxy- 4 methylbenzoyl)isopropyl] phenylazo) 1 naphthol. Such dye developers can be incorporated in the lightsensitive emulsions themselves, or they can be incorporated in a hydrophilic colloid (e.g., gelatin) layer located contiguous to the noble metal-selenium sensitized lightsensitive emulsion.

The present photographic systems can be used in the preparation of photographic products wherein a photographic developing agent is incorporated in a light-sensitive emulsion, or in a hydrophilic colloid layer contiguous with the emulsion, for example, in photographic products of the type described in Yutzy et al. U.S. Patent 2,725,298, issued November 29, 1955, or in Yutzy et al. U.S. Patent 2,739,890, issued March 27, 1956. The novel photographic systems of my invention can be used in the production of photographic products containing, for example, at least about 5 grams per mole of silver halide of a developing agent, such as 1-phenyl-3-pyrazolidone and wherein the emulsion is coated on a fibrous support which contains sufiicient moisture so that upon heating the exposed element, a negative silver image is obtained directly without the application of liquids. Such a product is described in Stewart et al. U.S. application Serial No. 221,031, filed September 4, 1962. This is not to say that the emulsions of my invention cannot be used in liquid systems which may or may not use a wide variety of processing solutions or viscous liquids, including systems which use pod processing. They can also be used in the preparation of photographic materials which are designed to be processed in non-aqueous systems or in systems designed to be processed by the application of steam.

The novel photographic systems of the invention can also be used in monobath processes such as are described in Haist et al. U.S. Patent 2,875,048, issued February 24, 1959, and in web-type processes, such as the one described in Tregillus et al. U.S. patent application Serial -No. 835,473, filed August 24, 1959, now U.S. Patent No. 3,179,517.

Also, the novel photographic systems of the invention can be used in the preparation of lithographic printing plates using, for example, techniques as described in Kodak French Patent 1,280,832, issued November 27, 1961.

It has been found that the photographic systems of my invention can contain, in addition to labile sulfur compounds, certain stabilizers or antifoggants that are particularly useful for reducing incubation fog. Useful stabilizing compounds for the emulsions of my invention include the salts of noble metals, especially palladium and platinum, including such salts as are described in Trivelli and Smith U.S. Patents 2,566,245, issued August 28, 1951, and 2,566,263, issued August 28, 1951. 7 Another group of stabilizers which are quite useful in my invention comprise the alkane-, areneand heterocyclic sulfinic acids and their water-soluble salts (sodium benzene sulfinate, methane sulfinic acid, ethane disulfinic acid, etc., includ ing stabilizers disclosed in Brunken U.S. Patent 2,057,764, issued October 20, 1936). Another group of useful stabilizing compounds include urazole stabilizers, such as urazole, l-phenyl dithiourazole, l-ethyl dithiourazole, etc., including stabilizers disclosed in Howe U.S. Patent 2,538,599, issued December 19, 1950. Other useful stabilizers include mercury compounds such as those disclosed in Allen et al. U.S. Patent 2,728,663, issued December 27, 1955; Carroll et al. U.S. Patent 2,728,664, issued December 27, 1955 and Leubner et al. U.S. Patent 2,728,665, issued December 27, 1955. It has also been found that the photographic systems of the invention can be further stabilized with disulfide compounds, including the cyclic disulfides of Kodak Belgian Patent 569,317, or the aliphatic disulfides of Herz and Kalenda U.S. Patent 3,043,696, issued July 10, 1962. Another group of disulfide stabilizing compounds which have useful effects in my invention include those containing a carbamylalkyl radical, wherein the carbamyl radical is aliphatic or cycloaliphatic (e.g., where the nitrogen atom of the carbamyl radical forms a part of a heterocyclic ring, such as pipen'dyl, morpholinyl, etc., as in the case of bis-(N- morpholinylcarbonyloxyethyl)-disulfide). Also useful in stabilizing the emulsions of my invention is Nitron and similarly constituted tetrazoles, particularly Nitron in combination with a salicylic acid such as 5-(1,1,3,3-tetramethylbutyl)salicylic acid. 1-phenyl-5-mercaptotetrazoles are useful stabilizers in the invention. Water-soluble salts of Group H elements of the Periodic Table such as magnesium, calcium, strontium, barium, cadmium and zinc, organic tertiary phosphines and azaindenes such as triazaindenes, tetrazaindenes and pentazaindenes are also useful stabilizers in the photographic systems of the invention. Typical suitable azaindenes are disclosed in Heimbach and Kelly U.S. Patents 2,444,605 and 2,444,606, issued July 6, 1948; Heimbach U.S. Patents 2,444,607, issued July 6, 1948, and 2,450,397, issued September 28, 1948; Heimbach and Clark U.S. Patent 2,444,609, issued July 6, 1948; Allen and Reynolds U.S. Patents 2,713,541, issued July 19, 1955, and 2,743,181, issued April 24, 1956; Carroll and Beach 13 U.S. Patent 2,716,062, issued August 23, 1955; Allen and Beilfuss U.S. Patent 2,735,769, issued February 21, 1956; Reynolds and Sagal U.S. Patent 2,756,147, issued July 24, 1956; Allen and Sagura U.S. Patent 2,772,164, issued November 27, 1956 and Z. Wiss. Phot., vol. 47, 1952, pages 2 to 28.

A particularly useful class of stabilizers or antifoggants that can be utilized to control fog in the photographic systems of the invention are the derivatives of hydroxy carboxylic acids described in the copending application of Humphlett, U.S. Serial No. 413,962, filed November 25, 1964, and which stabilizer addenda can be represented by the following Formulas A and B:

A. O I! ($11M)... o l (drum and wherein: M and Z are each hydroxy radicals or acyloxy radicals wherein R is an alkyl radical or an aryl radical); X is a hydrogen atom, an acyloxymethyl radical if (-CHgOCR wherein R is an alkyl radical or an aryl radical) or a carbinol radical (CH OH); Y is a carboxy radical II (-0 OH) 21 carbamyl radical II N112) or a radical having the formula II COR wherein R is an alkyl radical (more generally having 1 to 2 carbons, particularly when Z is a hydroxyl radical); A is a carbinol radical, a radical having the formula as described for Y, a carboxy radical, an acyloxymethyl radical or a carbamyl radical; m is an integer of 2 to 3; n is an integer of 1 to 5; and 0 is an integer of O to 2. The subject addenda contain at least one carbamyl or ester moietyincluding a or 6 lactone or inner ester groups (e.g., Formula A) as Well as the more conventional ester groups described above ii i (e.g., -ocr -oon Hence, at least one of A, Yand Z of Formula B forms a carbamyl or an ester radical. Typical useful antifoggant 'addenda can be represented by the following more subgeneric formulas:

wherein: R is an alkyl radical having 1 to 2 carbon atoms; R and R are each an alkyl radical which more generally has 1 to 8 carbon atoms or a phenyl radical, including substituted phenyl radicals; R is an alkyl radical which more generally has 1 to 8 carbon atoms or a hydrogen atom; p is an integer of 2 to 3; and q is an integer of 1 to 5. Other subgeneric formulas defining antifoggant addenda of the invention included within generic Formulas A and B can be formulated. The alkyl substituents described above suitably have 1 to 20 carbon atoms, and preferably 1 to 8 carbon atoms, including methyl, ethyl, isopropyl, butyl, heptyl, octyl, decyl, octadecyl, eicosyl and the like. The aryl substituents described above include such radicals as phenyl, tolyl, naphthyl and the like, phenyl being preferred.

The above-described stabilizers or antifoggants can be utilized in conventional antifoggant amounts, the amount utilized varying with the particular stabilizer and the elfect desired in accordance with usual practice. Mixtures or combinations of more than one of the above-described stabilizers can be utilized. Such stabilizers, e.g., the azaindenes and mercury salts, which are normally added just prior to coating can, if desired, be included during the chemical sensitization of the silver halide emulsion.

The photographic systems stabilized with a labile sulfur compound in accordance with the invention can be any photographic system that is sensitized with noble metals and labile selenium. The invention thus has utility, not only for silver halide photographic systems, but also, for other light-sensitive systems such as other light-sensitive silver salts, thallous halides, cuprous halides, lead halides and related light-sensitive heavy metal salts.

The following examples will serve to illustrate the useful stabilizing effects obtained in my invention when combinations of noble metal sensitizers and selenium sensitizers are employed.

Example 1 dimethylselenourea (a labile selenium compound) and 4.0

mg. per mole of potassium chloroaurate, this emulsion being further modified by the addition of mg. per mole of sodium thiocyanate (Coating B). The third portion of emulsion was sensitized exactly as in the case of the second portion of emulsion, except that 8.0 mg. per mole of sodium thiosulfate (a labile sulfur compound) were added (Coating C). Each of the portions of emulsion was then coated on a cellulose acetate film support 15 and dried, the coating samples being designated A, B and C, respectively, in Table I. The samples were then exposed in the usual manner on an Eastman Ib sensitometer and developed for minutes at 72 F., fixed in hypo,

of 540 mg, of silver and 400 mg. of gelatin per square foot. A sample of each coating was exposed in an Eastman Ib sensitometer, developed for 8 minutes at 72 F., fixed in hypo, washed and dried in the usual manner.

washed and dried in the usual manner. The developing 5 The developing composition utilized had the following composition utilized is set out below: composition:

Grams Grams gI n.1ethyl-p ammop henol Sulfate u N-methyl-p-aminophenol sulfate 2.0 odiumsulfite (anhydrous) 30.0 S lfit h d 90 O Hydroquinone 2.5 10 0 mm e an y mus S Hydroqumone 8,0

0 rum metaborate octahydrate 10.0 Potassium bromide u 05 Sodium carbonate monohydrate 52.5 Water to make 1.0 liter. Potassium bmmlde Water to make 1.0 liter. The results are summarized in the data set out in Table I. TABLE In TABLE I Coating Sulfur Compound Relative 'y Fog Rela- Speed Coating Feature Addenda (mg/Ag mole) tive Fog speed (A). None 100 3.26 0.23 0 (B) Sodium thiosull'ate 100 3.48 0.15 Sulfur (1G.0)+gold (4.0) 100 .08 Selenium (3.2)+g0ld (4.0).. 132 .20

Sulfur (8.0)+gold (4.0)|selemum (1.6) 141 07 Exampl 4 As illustrated by the data set out in Table I, the labile A fi e- Siivei' gelatin) Fhioiobromide emuisiofl ulf Compound fi ti ly controlled h f h fog containing 60 mole percent bromide was chemically sensior sensitizing fog of the selenium-gold sensitized emuliiZeCi y adding, p mole of SiiVei' e b of P sion. Similar results were obtained when a fine-grained iasslilm ChiOTO'fmIeTe, 50 of Sodium Y gelatino silver chlorobromide (60 mole percent bromide) gof N,N'd1meii{Yi5eieI10ufea,. and 2 gof Sodlllm emulsion was treated with a labile sulfur compound (e.g., iiilosilifaie f heeilng for 10 minutes at C" the P 10 g. of sodium thiosulfate) in addition to being selenium 0f the emuisloi} being at fiuiiilg epe i of sand gold sensitized as dgscribed above A second portion was chemically sensitized 1n the same manner but with the addition of 220 mg. of 4-hydroxy-6- Example 2 methyl-1,3,3a,7-tetraazaindene per mole of silver halide A moderately coarse-grained, gelatino silver bromoand heated for the same time, at the same temperature iodide emulsion containing 3.24 mole percent iodide was and p The Chemically sensitized emulsions were each chemically sensitized by adding, per mole of silver halide, coated on cellulose acetate film supports at coverages of 2 mg. of potassium chloroaurate, 100 mg. of sodium thio- 540 mg. of silver and 400 mg. of gelatin per square foot. cyanate, and 0.8 mg. of N,N-dimethylselenourea and heat- A sample of each coating was exposed on an Eastman ing for 30 minutes at 60 C. (Coating A). Other por- Ib sensitometer and processed as described in Example 3. tions (Coatings B and C), were chemically sensitized in TABLE IV the same manner but with the addition of a labile sulfur compound as shown in Table II and heated at the time Coating Amount of Azamdene Relative 7 Fog and temperature shown in Table II. The chemically sen- Speed sitized emulsions were each coated on a cellulose acetate support at coverages of 540 mg. of silver and 500 mg. of (A)- Nnne 100 5,30 0,14 gelatin per square foot. A sample of each coating was (B) 220 mg'hmie sliver 100 exposed on an Eastman lb sensitometer and processed as described in Example 1. Similar results are obtained if mercury salts are substi- TABLE II Ctg. Sulfur Compound (mg/mole) Time. Temp. of Relative 'y Fog Heat Treatment Speed (A) None 100 3.06 0. 26 (13).--- Diacetylthiuurea (1 mg.) 100 3. 34 0.12 (0)...- Isopropylthiocarbamate (2 mg.) 95 3.50 0.09

Similar results as those described in Table II are obtained tuted for the tetraazaindene as antifoggants (e.g., 1 mg. it 0.8 mg. of colloidal selenium per mole of silver halide of mercuric chloride per mole of silver halide). Mixtures were substituted for the N,N-dimethylselenourea as the 0 of such azaindenes and mercury salts are also useful anti labile selenium addendum. foggant combinations. Likewise, 300 mg. of 5carbeth- Example 3 oxy-2,6-dirnethyl-4-thiopyrimidine per mole of silver halide substituted for the tetraazaindene further reduced A moderately fine-grained, gelatino silver bromoiodide the fog level. emulsion containing 5.2 mole percent iodide was chemi- Example 5 cally sensitized by adding, per mole of silver halide, 3 mg. of potassium chloroaurate, 100 mg. of sodium thiocyanate, A fi i gelatin) f f bromolodldf i and 24 of NN dimethylselenourea and heating for containing 4.2 mole percent iodide was chemically sensi- 10 minutes at c. (Coating A). A second portion was e by addmg, P mole 0f Sliver f 2 0f chemically sensitized by adding, per mole of silver halide, 70 tasslum chloroaurate, 100 of Sodium thiocyanaie, 4 mg. of potassium chloroaurate, 100 mg. of sodium thioof N,Ndimethyiseienourea, and 4 mg of Sodium t 34 mg of N,Ndimethylselenourea and 4 thiosulfate and heating for 10 minutes at 65 C. (Coatof sodium thiosulfate and heating 12 minutes at 60 C. ing A Second Portion Was Chemically sensitized in (Coating B). The chemically sensitized emulsion was the Same manner but with the addition of 267 mg. 4- coated on a cellulose acetate film support at a coverage hydroxy-6-methyl-1,3,3a,7-tetraazaindene per mole of TABLE V Coating Amount of Tetraazaindene Relative 7 Speed Fog Similar results as those set out in Table V were obtained when 400 mg. of -acetamido-4-hydroxy-6-methyl-1,3,3a, 7-tetraazaindene per mole of silver halide or 400 mg. of 2 methyl-mercapto 4 hydroxy-6-methyl-l,3,3a,7-tetraazaindene per mole of silver were substituted for the 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene. Such tetraazaindenes also substantially reduced the fog level of the coatings that were incubated for one week at 120 F. and 50% RH.

Example 6 A moderately coarsegrained gelatino silver bromoiodide emulsion containing 3.24 mole percent iodide was chemically sensitized by adding, per mole of silver halide, 2 mg. of potassium chloroaurate, 100 mg. of sodium thiocyanate, and 4 mg. of tri-p-tolylselenophosphate and heating for 15 minutes at 65 C. (Coating A). A second portion was chemically sensitized in the same manner, but with the addition of 2 mg. sodium thiosulfate and heated for the same time at 65 C. (Coating B). The chemically sensitized emulsions were coated on cellulose acetate fi-lm supports. A sample of each coating was exposed on an Eastman Ib sensitometer and processed as described in Example 1.

TABLE VI Coating Relative 'y Fog Sulfur Compound Speed None- Sodium thiosul fate The -tri-p-tolylselenophosphate used in this example was prepared by the method described by Heiks and Croxton in Industrial and Engineering Chemistry, vol. 43 (1951), page 876. Such selenium compounds can be called selenophosphates and can be represented by the following general formula:

wherein R represents an alkyl radical, such as butyl, isopropyl, amyl, isoamyl, etc., or an aromatic radical, such as phenyl, tolyl (o, m or p), etc. Such selenium compounds can be used as labile selenium compounds in sensitizing the emulsions of the invention.

Example 7 'A moderately coarse-grained gelatino silver bromo iodide emulsion containing 3.24 mole percent iodide was chemically sensitized by adding, per mole of silver halide, 2 mg. of potassium chloroaurate, 100 mg. of sodium thiocyanate, and 2.6 mg. of selenobenzophenone and heating for 20 minutes at C. (Coating A). Other portions were chemically sensitized in the same manner, but with the addition of sodium thiosulfate in the amounts shown below, and heated at 65 C. for the length of time shown in Table VII (Coatings B and C). The chemically sensitized emulsions were then coated on cellulose acetate filrn supports. A sample of each coating was exposed on an Eastman Ib sensitometer and processed as described in Example 1.

To one mole of a gelatino silver bromoiodide (94 mole percent bromide, 6 mole percent iodide) photographic emulsion was added 2 mg. potassium chloroaurate, 2 mg. sodium thiosulfate pentahydrate, 100 mg. sodium thiocyanate and 1.6 mg. N,N-dimethylselenourea. The emulsion was then digested at 60 C. to obtain optimum sensitivity. The emulsion was then divided into several portions to which were added the concentrations of the addenda listed in Table VIII below. The emulsions were then coated on a film support to yield a silver coverage of 540 mg. per square foot and a gelatin coverage of 500 mg. per square foot. Samples of fresh and incubated coatings were exposed in an Eastman Ib sensitometer and processed as described in Example 1 to yield the following results:

TABLE VIII Fresh One Week Inc.

120F.50%R.H. Feature Addenda (gJAg mole) Rel. 1 Fog Rel. 1 Fog Speed Speed Control 100 2. 64 0. 16 120 1. 42 1. 94 Control plus Compound II (10.0). 100 2. 64 0. 12 95 2. 20 0. 98 Control plus Compound II (20.0) 105 2. 64 0. 12 100 2. 42 0. Cont ol plus Compound III (20 0) 91 2. 66 0.12 69 1. 93 1. 30 Control plus Compound IV (10.0) 100 2.70 0.16 120 1. 86 1.38 Control plus Compound 1 (2.0) 100 3.00 0.07 138 2.80 0.17 Control plus Compound I (2.0) plus Compound II (10.0) 100 2. 84 0. 06 115 2. 70 0. 13 Control plus Compound I (2.0) plus Com- 0) plus Compound III (20.0) 2. 94 0. 06 2. 50 0. 11 Control plus Compound I (2.0. plus Compound IV (10.0) 105 2. 80 0. 08 120 2. 50 0. 24 Control plus Compound I (2.0) plus Cornpound IV (20.0) 2.82 0. O6 2. 62 0.18

19 In the above table, Compound I is 4-hydroxy-6-methyl-l,3, 3a,7-tetraazaindene, Compound H is methyl-L-arabonate, Compound III is D-arabonamide and Compound IV is 'glucono-y-lactone. Other related hydroxy carboxylic acid derivates that can also be suitably utilized as antifoggants in the described gelatino silver bromoiodide emulsion at concentrations of 20 grams per mole of silver halide, or in combination with 2 grams per mole of silver halide of 4-hydroxy-6-methyl-l,3,3a,7-tetraazaindene, include: diethyl mucate, methyl D-arabonate, ethyl D-ara-bonate, methyl L-arabonate tetraacetate, D-arabono- -lactone, isopropyl L-arabonate, isobutyl D-arabonate tetraacetate, methyl (tetraacetyl-D-arabonyl)glycolate, D gluco-D- guloheptone- -lactone, D gl-uco-D-gulo heptonoamide, methyl D,L-glycerate, dimethyl D-tartrate, D-glucono-filactone, D-gluco-namide, D-gluco-D-guloheptonic acid hexaacetate monohydrate, D-galactonic acid pentaacetate, D-arabono-y-lactone, D-galactonamide, D-lyxono-y-lactone, D-mannonamide, and the like. Such hydroxy carboxylic acid derivatives can be utilized in a wide range of autifoggant concentrations, although concentrations of about 5 to 100 grams per mole of silver halide are generally utilized.

Example 9 A coating of vacuum deposited silver bromide is made on a cellulose acetate film support and overcoated with a thin layer of gelatin by the method described in Example 1 of copending Rasch et al. application U.S. Serial No. 415,596, filed December 3, 1964. The resulting photographic element is immersed for five minutes at 68 F. in the following sensitizing solution:

Mg. Sodium thiosulfate 4.00 Potassium chloroaurate 4.00 N,N-dimethylselenourea 0.25 Water to make 200.00 ml.

(pAg adjusted to 8.5 with aqueous potassium bromide.)

The resulting treated photographic element is then allowed to air dry in the dark at 68 F. The resulting dried photographic element is then exposed to roomlight for 10 seconds through a neutral density stepwedge and developed for 10 seconds in Kodak D-72 developing solution, fixed in hypo, washed and dried in the usual manner. The fog level of the resulting processed photographic element is low when compared to a similarly exposed and processed photographic element prepared in the same manner except that the sodium thiosulfate is omitted from the sensitizing solution.

Example 10 To a fine-grained gelatino silver chlorobromide emulsion containing 60 mole percent bromide and 40 mole percent chloride was added 4.4 mg. of potassium chloroaurate, 50 mg. of sodium thiocyanate, 2.2 mg. of N,N- dimethylselenourea, and 2 mg. of sodium thiosulfate, and the emulsion heated at about 60 C. for about minutes. Thereafter to separate portions of the emulsion were added the antifoggants listed in Table IX below and the emulsions were coated on cellulose acetate film supports at coverages of 137 mg. of silver and 202 mg. of gelatin per square foot. Samples of the films were exposed in an Eastman lb sensitometer, both before and after an incubation period and processed as described in Example 3. The data set out in Table IX illustrates that S-mercaptotetrazoles can be utilized in emulsions of the invention to reduce incubation fog.

2% TABLE 1X Fresh One Week Ine.,

120 F. Compound MgJAg mole Rel. y Fog Rel. 7 Fog Speed Speed None Control 100 1. 96 0.10 91 0.78 (A). "2-- 500 91 1.88 0.06 120 1.75 0.27

B 94 1. 86 0. 18 1%0 Control 1. 96 0. 1 7 2" 90 94 2. 08 0.07 91 1.63 0. 24

The compounds of Table IX are identified as follows:

(A) :1- 3-acetamidophenyl) -5- mercaptotetraz0le (B) :1-(3,5-dicarboxyphenyl)-o-mercaptotetrazole (C) :1- o-curhomethoxyphenyl) -5-mercaptotetrazole Example 11 A moderately coarse-grained, gelatino thallous bromoiodide emulsion containing 13 mole percent iodide and 87 mole percent bromide is chemically sensitized by adding, per mole of thallous halide, 10 mg. of potassium chloroaurate, 40 mg. of seleno-DL-cystine and 10 mg. of sodium thiosulfate, and thereafter heating for 10 minutes at 40 C., then cooling to 35 C. The chemically sensitized emulsion is coated on a cellulose acetate film support at a coverage of 306 mg. of thallium and 450 mg. of gelatin per square foot. A sample of coating is hardened by bathing 5 minutes in a 3 percent solution of potassium chrome alum, washed, and dried. The sample is exposed through a step tablet for 5 minutes with a SOO-watt photoflood lamp at a distance of 9 inches. The exposed sample is processed at 68 F. by bathing 5 minutes in a 10 percent silver nitrate solution, washing 1 minute in distilled water, bathing 5 minutes in a 2 percent potassium bromide solution, washing 1 minute in distilled water, developing 4 minutes in the developer described in Example 3, followed by the usual fixing in hypo, washing, and drying. A similar coating of an emulsion prepared in the absence of the labile sulfur compound, sodium thiosulfate, during the chemical sensitization has a substantially higher fresh fog level when exposed and processed as described above. The preparation of thallous bromide and thallous bromoiodide emulsions is described in papers by J. A. Thom, Sci. et Ind. Phot. (2), 18, 193-204 (1946); N. Ritchie and J. A. Thom, Trans. Far. Soc. 42, 418 (1946); and E. Brauer and H. J. Wehran, Phot. Korr. 93, 67 (1957). Chemical sensitizations of thallous bromoiodide emulsions by rhodium chloride, gold chloride, sodium thiosulfate, cystine, and active gelatins (alone or in combination) are described in papers by E. Brauer, Phot. Korr. 94, 35 (1958), E. Brauer, Phot. Korr., 93, 67 (1957), and E. Brauer, Sci. et Ind. Phot. (2), 29, 161 (1958).

Example 12 In a manner similar to that described in Table G, column 25 of US. Patent 3,046,129, issued July 24, 1962, a conventional photographic gelatino silver bromoiodide emulsion was divided into three aliquot portions, each portion containing a conventional magenta coupler, such as one of those identified in Fierke et al. US. Patent 2,801,171 (e.g., coupler No. 7). A sample of the emulsion is sensitized to its optimum sensitivity with aurous thiosulfate at 3.3 mg. per mole of silver halide and dimethylselenourea at 0.2 mg. per mole of silver halide, the emulsion containing sodium thiosulfate at 2 mg. per mole of silver halide during the sensitization. The emulsion is coated on a cellulose acetate film support and dried. The film sample is then exposed to daylight quality illumination in an Eastman Ib sensitometer and given a conventional negative development in the developing composition as described in Example 1. The coating is then flashed to white light and developed once again in an alkaline color developing composition con- 21 taining 4=amino-N,N-diethyl-3-methylaniline hydrochloride as the active developing agent. The metallic silver is then removed by successive treatments with a ferricyanide bleach bath and fixing bath, followed by water washing in the usual manner. A reversal magenta image is obtained.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinaoove and as defined in the appended claims.

Iclaim:

1. In a photographic system sensitized with a noble metal and labile selenium, the improvement which comprises utilizing a labile sulfur compound as a stabilizer.

In a photographic system sensitized with gold and labile selenium, the improvement which comprises utilizing a labile sulfur compound as a stabilizer.

3. In a silver halide system sensitized with gold and labile selenium, the improvement which comprises utilizing a labile sulfur compound as a stabilizer.

4. A photographic silver halide emulsion sensitized with at least two different sensitizers,'one of said sensitizers being a noble metal sensitizer and the other being a labile selenium sensitizer, said silver halide emulsion being stabilized by the addition thereto of a labile sulfur compound.

5. A photographic silver halide emulsion sensitized with at least two different sensitizers, one of said sensitizers being a gold salt and the other being a labile selenium sensitizer, said silver halide emulsion being stabilized by the addition thereto of a labile sulfur compound.

6. A photographic silver halide emulsion sensitized with a gold salt and an organic selenium compound containing divalent selenium doubly bonded to a carbon atom of said compound through a covalent linkage, said silver halide emulsion being stabilized by the addition thereto of a labile sulfur compound.

7. A photographic silver halide emulsion sensitized With a gold salt and a labile selenium sensitizer, said silver halide emulsion being stabilized by the addition thereto of a labile sulfur compound and a tetraazaindene antifoggant.

8. A photographic silver halide emulsion sensitized with a gold salt and a labile selenium sensitizer, said silver halide emulsion being stabilized by the addition thereto of a labile sulfur compound and a mercury compound antifoggant.

9. A photographic gelatino silver halide emulsion sensitized with a gold salt and a labile selenium sensitizer, and containing a labile sulfur compound as a stabilizer.

10. A photographic silver halide emulsion as described in claim 4 wherein the labile selenium sensitizer is a selenourea.

11. A photographic silver halide emulsion as described in claim 4 wherein the labile selenium sensitizer is a selenophosphate.

12. A photographic silver halide emulsion as described in claim 4 wherein the labile sulfur compound is a thiosulfate.

13. A photographic silver halide emulsion as described in claim 4 wherein the emulsion contains a color-forming photographic coupler.

14. A photographic silver halide emulsion as described in claim 4, sensitized in the presence of a watersoluble thiocyanate.

15. A photographic silver halide emulsion as described in claim 5 wherein the labile selenium sensitizer is N,N-dimethylselenourea.

16. A photographic silver halide emulsion as described in claim 5 wherein the labile sulfur compound is sodium thiosulfate.

22 17. A photographic silver halide emulsion as described in claim 5 wherein the labile sulfur compound is u G i (outing, o and (UHZ)n H (nmo X wherein:

(l) M and Z are each selected from the group consisting of a hydroxy radical and an acyloxy radical having the formula i o CR wherein R is selected from the group consisting of 12.11 alkyl radical and an aryl radical;

(2) X is selected from the group consisting of a hydrogen atom, a carbinol radical, a radical having the formula II -OH2OCR wherein R is selected from the group consisting of an alkyl radical and an aryl nadical;

(3) Y is selected from the group consisting of a carboxy radical, a carbamyl radical and a radical having the formula ll GOR1 wherein R is an alkyl radical;

(4) A is selected from the group consisting of a carbinol radical, a carbamyl radical, a carboxy radical, a radical having the formula u OOR wherein R is an alkyl radical and a radical having the formula i oHzohR wherein R is selected from the group consisting of an alkyl nadical and an aryl radical;

(5) m is an integer of 2 to 3;

(6) n is an integer of 1 to 5; and

(7) o is an integer of 0 to 2; except that at least one of A, Y and Z forms a radical selected from the group consisting of a carbamyl radical and an ester radical.

22. A photographic silver halide emulsion as described in claim 5 wherein the labile selenium sensitizer is colloidal selenium.

No references cited.

NORMAN G. TORCHIN, Primary Examiner.

J. RAUBITSCHEK, Assistant Examiner.

Claims (1)

1. IN A PHOTOGRAPHIC SYSTEM SENSITIZED WITH A NOBLE METAL AND LABILE SELENIUM, THE IMPROVEMENT WHICH COMPRISES UTILIZING A LABILR SULFUR COMPOUND AS A STABILIZER.