US3676135A - Process for forming dye images - Google Patents

Abstract

FORMAZAN DYE IMAGE DENSITIES FORMED BY TREATING A PHOTOGRAPHIC METAL IMAGE IN A HYDROPHILIC COLLOID BINDER LAYER WITH A TETRAZOLIUM SALT SOLUTION IN THE PRESENCE OF A METAL COMPLEXING LIGAND ARE ENCHANCED BY THE PRESENCE IN SAID BINDER LAYER OF A DISPERSION OF AT LEAST ONE HIGHBOILING SUBSTANTIALLY COLORLESS, CRYSTALLOIDAL ORGANIC OIL, THE WEIGHT RATIO OF OIL TO HYDROPHILIC COLLOID PREFEREABLY BEING IN THE RANGE OF FROM ABOUT 10:1 TO ABOUT 1:30 AND THE DISPERSED PARTICLES OF THE OIL PREFERABLY HAVING DIAMETERS IN THE RANGE UP TO ABOUT 2U.

Description

United States Patent 01 3,676,135 Patented July 11, 1972 3,676,135 PROCESS FOR FORMING DYE IMAGES Walter J. Musliner, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, NY. No Drawing. Filed June 22, 1970, Ser. No. 48,546

Int. Cl. G03c 7/00 us. or. 96-54 14 Claims ABSTRACT OF THE DISCLOSURE This invention is related to photography, photographic elements, compositions for use in photographic processing and photographic processes for forming high density dye images from photographic metal images.

In photography, it is sometimes desired to convert a photographic metal image into a dye image or to add to a photographic silver image a corresponding dye image. Processes are desired that will make it possible to obtain photographic reproductions having good image densities with elements containing less silver than usual or with photographic silver images having lower image densities than needed. 'If a dye image alone is desired, it is necessary to provide a convenient method for removing the metallic 1mage.

Processes have been described in British Pat. 908,299 in which a silver image in a photographic emulsion layer is converted into a formazan dye image .by treating the silver image with a tetrazolium salt in the presence of cyanide ions and, subsequently, bleaching the image with a ferricyanide bromide bleach bath, followed by washing, fixing with a sodium thiosulfate bath, washing and drying. It is desired to prepare higher density dye images from metal images than is possible from the prior art processes.

It is an object of my invention to provide a novel process for converting a novel photographic metal image in the presence of certain organic oils into a higher density dye image than is possible with the prior art processes and preferably without using cyanide ions and without a separate bleach step and a separate fixing step.

Another object of my invention is to provide a novel, single-step process for converting a metal image to a high density formazan dye image and, simultaneously, to remove the metal image from a black-and-white developed photographic element.

Still another object of my invention is to provide a novel method which is valuable for the conversion of even a low density silver image into a formazan dye image of a density higher than previously realized with the same dyes.

Still another object of my invention is to enhance an image or improve the image contrast obtainable from a silver image alone, by the use of high density formazan dye images. 1 i

Still another object of my invention is to provide a novel photographic element for producing silver images which are convertible to formazan dye images of higher density and higher covering power than formazan dye images produced from silver images in elements outside my invention.

Still other objects of my invention will become apparent from a consideration of the following specification and claims.

These and still other objects of my invention are accomplished by making my novel photographic element comprising a support coated with at least one hydrophilic colloid layer containing a dispersion of light-sensitive metal salt, preferably, silver halide grains and a dispersion of particles of a high-boiling crystalloidal organic oil that is substantially solute-free (i.e., contains substantially no dissolved material, e.g., color-forming couplers, dyes, ultraviolet-absorbing compounds, brightening agents, etc.), and using this photographic element which contains substantially no color-forming coupler to make a metal image with a standard oxidation potential more positive than -0.98 volt and then replacing at least part of this metal image with a formazan dye image by contacting the metal image with an aqueous solution of a tetrazolium salt (T-salt) until the T-salt oxidizes the metal image to a metal ion and the T-salt is reduced to the corresponding formazan dye in situ. The T-salt is used in the presence of a metal complexing ligand that forms a metal complex. This metal complexing ligand is either (1) a separate compound in the T-salt solution or (2) a moiety of the T-salt molecule, or the complexing function is filled by a combination of (1) and (2). The formazan dye which is produced from the T-salt is nondilfusible and replaces at least a portion of the metal image.

The formazan dye image formed remains at the site of the original zero valent metal image that has been converted to a metal ion. The metal ion is complexed as part of the formazan dye when the T-salt (and formazan dye formed from it) contains a moiety that is a metal ion complexing agent, or the metal ion is removed by a fixing step or the use of a complexing agent which renders the metal ion solution and which is present in the T-salt solution. Alternatively, the metal ion is reconverted to the zero valent metal image by a subsequent reduction step so the formazan dye image formed previously is supplemented by a metallic image.

My invention is characterized by forming an insoluble formazan dye image at the site of a zero valent metal image in a hydrophilic colloid binder and in the presence of a dispersion of at least one high-boiling crystalloidal organic oil that is preferably substantially colorless. My organic oils have molecules that contain at least one polar group such as an ester group, an amide group, an imide group, a ketone group, a hydroxyl group, an oxygen ether group and a halogen atom. The particles of dispersed organic oils used in my photographic elements advantageously have diameters in the range up to about 2 and preferably in the range up to about I in diameter. The weight ratio of my organic oil to the hydrophilic colloid binder is advantageously in the range of from about 1:0.1 to about 1:30 with a preferred range of from about 1:1 to about 1:35. The presence of my dispersed organic oil in a hydrophilic colloid layer with a zero valent metal image, produces a valuable increase in the formazan dye image density, especially in the D that is obtained from a given zero valent metal image density. The zero valent metal image is advantageously formed in any photographic element containing an appropriate light-sensitive metal salt prepared in a hydrophilic colloid binder that contains one of my high-boiling crystalloidal organic oils.

In accordance with my invention, I have found that the above objects are accomplished by forming formazan dye images in hydrophilic colloid layers from metal images in the presence of a dispersion of at least one high-boiling (i.e., above about 175 C.) crystalloidal organic oils represented by the following formulas:

wherein R R R R R and R each represent the same or a diiferent member, e.g., hydrogen, halogen (e.g., chlorine, bromine, fluorine, etc.), an alkyl group of from 1 to 20 carbons (e.g., methyl, ethyl, propyl, butyl, amyl, phytyl, etc.), a phenyl group (e.g., phenyl, tolyl, chlorophenyl, etc.), an alkoxy group of from 1 to 20 carbons (e.g., methoxy, ethoxy, phytyloxy, etc.), a phenoxy group (e.g., phenoxy, tolyloxy, etc.);

R (II) 2 (H) wherein R and R are as defined previously and R represents a group, such as, an alkyl group of from 1 to 20 carbons (e.g., methyl, ethyl, propyl, butyl, hexyl, phytyl, etc.), an aryl group, such as, a phenyl group (e.g., phenyl, tolyl, ethylphenyl, chlorophenyl, methoxyphenyl, etc.), etc.;

u and wherein R and R represent the same or different group, such as, an alkyl group of from 1 to 20 carbons (e.g., methyl, ethyl, propyl, 2,3-dihydroxypropyl, butyl, decyl, pentadecyl, nonadecyl, benzyl, etc.), an aryl group [e.g., a phenyl group (e.g., phenyl, tolyl, ethylphenyl, amylphenyl, methoxyphenyl, ethoxyphenyl, chlorophenyl, dichloropehnyl, etc.), a-naphthyl, B-naphthyl, etc.]; R represents a group, such as, an alkyl of from 1 to 20 carbons (e.g., methyl, benzyl, ethyl, butyl, hexyl, butoxymethyl, methoxyethyl ethoxymethyl, pentadecyl, nonadecyl, etc.), an aryl group [e.g., a phenyl group (e.g., phenyl, tolyl, ethylphenyl, chlorophenyl, methoxyphenyl, etc.), anaphthyl, fi-naphthyl, etc.], and L represents a divalent group, e.g.,

-CH OH 0 CHzO 1R1 group and a group wheerin R and R are as defined previously and n rep resents an integer of from 2 to 3;

o 0 ll Ru0 ZCOR3 wherein R is as described previously, Z represents a group, such as, -CH=CH-, (CH etc.; in represents an integer of from 1 to 10; R represents a group such as is defined for R ORB m wherein R and R are as defined previously and R represents a member such as hydrogen, an alkyl group of from 1 to 20 carbons (e.g., methyl, ethyl, butyl, dodecyl, phytyl, etc.), an alkoxy group of from 1 to 20 carbons (e.g., methoxy, ethoxy, butoxy, phytyloxy, etc.), a halogen atom (e.g., clorine, bromine, fluorine, etc.);

(VII) 0 wherein R is a defined previously; R represents a member, such as, hydrogen, an alkyl group of from 1 to 20 carbons (e.g., methyl, ethyl, butyl, phytyl, benzyl, phenethyl, etc.), an aryl group [e.g., a phenyl group (e.g., phenyl, tolyl, butylphenyl, methoxyphenyl, chlorophenyl, etc.), a naphthyl group (e.g., a-naphthyl, ,6- naphthyl, etc.)] and nonmetallic atoms which, taken together with R and the nitrogen atom between R and R from a 5- to 6-membered heterocyclic ring (e.g., a piperidyl group, a morpholinyl group, etc.), and R represents a member, such as, hydrogen, an alkyl group of from 1 to 20 carbons (e.g., methyl, ethyl, butyl, phytyl, benzyl, phenethyl, etc.), an aryl group [e.g., a phenyl group (e.g., phenyl, tolyl, butylphenyl, methoxyphenyl, chlorophenyl, etc.), a naphthyl group (e.g., rat-naphthyl, ,B-naphthyl, etc.)] and the nonmetallic atoms which when taken together with R and the nitrogen between R and R12, form a 5- to 6-membered heterocyclic ring (e.g., a piperidyl group, a morpholinyl group, etc.);

wherein Z, R and R are as defined previously; R represents a member, such as, hydrogen, an alkyl group of from 1 to 20 carbons (e.g., methyl, ethyl, butyl, phytyl, benzyl, phenethyl, etc.), an aryl group [e.g., a phenyl group (e.g., phenyl, tolyl, butylphenyl, methoxyphenyl, chlorophenyl, etc.), a naphthyl group (e.g., a-naphthyl, fl-naphthyl, etc.)] and nonmetallic atoms which, taken together with R and the nitrogen atom between R and R form 5- to 6-membered heterocyclic ring (e.g., a piperidyl group, a morpholinyl group, etc.), and R represents a member, such as, hydrogen, an alkyl group of from 1 to 20 carbons (e.g., methyl, ethyl, butyl, phytyl, benzyl, phenethyl, etc.), an aryl group [e.g., a phenyl group (e.g., phenyl, tolyl, butylphenyl, methoxyphenyl, chlorophenyl, etc.), a naphthayl group (e.g., 0cnaphthyl, fl-naphthyl, etc.] and the nonmetallic atoms which, when taken together with R and the nitrogen between R and R form a 5- to 6-membered heterocyclic ring (e.g., a piperidyl group, a morpholinyl groun. etc.);

wherein R is as defined previously and D represents a divalent group, such as, -(CH CH=CH-,

where R-, is as defined previously and R represents an alkyl group of from 8 to carbons (e.g., octyl, decyl, dodecyl, pentadecyl, octadecyl, etc.), an aryl group [e.g., a phenyl group, (e.g., phenyl, tolyl, ethylphenyl, amylphenyl, methoxyphenyl, ethoxyphenyl, chlorophenyl, dichlorophenyl, etc.), a-naphthyl, ,B-naphthyl, etc.];

wherein R represents an alkyl group of from 7 to 20 carbons (e.g., octyl, decyl, dodccyl, pentadecyl, octadecyl, butylphenoxyethyl, octyloxyethyl, benzyl, a-hexylbenzyl, etc.), a 4-alkylaryl group in which the alkyl group has from 1 to 20 carbons [a 4-alkylphenyl group (e.g., 4-amylphenyl, 2,4-diamylphenyl, 4-methylphenyl, 4-dodecylphenyl, 4 dodecyl 2 chlorophenyl, 4-amyl-2-methoxyphenyl, etc.), a 4-alkylnaphthyl group (e.g., 4-methyl-u-naphthyl, 4-dodecyl-u-naphthyl, etc.); and

wherein R represents an alkyl group of from 1 to 20 carbons (e.g., methyl, ethyl, butyl, octyl, phytyl, fi-hydroxyethyl, fi-hydroxyethoxyethyl, B-ethoxyethoxyethyl, acetoxyethoxyethyl, etc.), a phenyl group (e.g., phenyl, tolyl, ethylphenyl, butylphenyl, chlorophenyl, methoxyphenyl, ethoxyphenyl, etc.) and R represents an alkyl group of from 2 to 20 carbons (e.g., ethyl, butyl, dodecyl, phytyl, etc.) and an aryl group, such as, a phenyl group (e.g., phenyl, tolyl, methoxyphenyl, ethoxyphenyl, butoxyphenyl, decylphenyl, allylphenyl, etc.) and a naphthyl group (e.g., a-naphthyl, fi-naphthyl, etc.) and preferably where R and R have a total of at least 9 carbon atoms. Typical examples of organic esters of inorganic acids, such as, phosphate esters of Formula I and sulfonate esters of Formula II include the following:

Triphenyl phosphate Tricresyl phosphate Diphenyl mono-p-tert. butyl phenyl phosphate Monophenyl di-p-tert. butyl phenyl phosphate Diphenyl mono-o-chlorophenyl phosphate Monophenyl di-o-chlorophenyl phosphate Tri-p-tert. butyl phenyl phosphate T ri-o-phenylphenyl phosphate Di-p-tert. butyl phenyl mono (S-tert. butyl-Z-phenylphenyl) phosphate Methyl p-toluenesulfonate Phenyl p-toluenesulfonate Hexyl p-toluenesulfonate Methyl methoxybenzenesulfonate Typical examples oforganic esters of monobasic organic acids of Formulas HI and IV include the following:

Ethyl-m-naphthoate Methyl o-methoxybenzoate Butyl o-rnethoxybenzoate u-Naphthyl acetate Tetrahydrofurfuryl benzoate Benzyl benzoate n-Hexyl benzoate Ethyl palmitate Ethyl o-anisate Resorchinol diacetate Ethylene glycol dilaurate Triacetin Tripropionin Trivalerin Typical examples of organic esters of dibasic organic acids of Formulas V and VI include the following:

Methyl abietate p-Ethoxyethyl sebacate fl-Ethoxyethyl maleate fi-Ethoxyethyl adipate Tetrahydrofurfuryl succinate Ethyl benzyl malonate Methyl phthalate Ethyl phthalate Propyl phthalate n-Butyl phthalate n-Amyl phthalate Iso-amyl phthalate Octyl phthalate Benzyl phthalate fl-Methoxyethyl phthalate fl-Ethoxyethyl phthalate fi-Butoxyethylphthalate Typical examples of amides having Formulas VII and VHI include the following:

Acetyl n-butyl aniline Acetyl methyl p-toluidine Benzoyl piperidine N-amyl succinamide Typical examples of imides of Formula IX include the following:

N-n-amylphthalimide N-n-amyl succinimide N-2-cyanobutylphthalimide Typical examples of ketones of Formula X include the following:

Benzophenone 2,4'-dichlorobenzophenone a-Methoxy acetophenone Acetophenone 2,4-dihydroxy valerophenone p-Sec.-amylbenzophenone Typical examples of alcohols of Formula XI include the following:

Heptadecanol n-Hexanol Octyl alcohol n-Hexylphenylcarbinol fl-(p-tert. butyl phenoxy)-ethyl alcohol Typical examples of ethers of Formula XII include the following:

Ethylene glycol monobenzyl ether Diethylene glycol monobutyl ether Diethylene glycol monobutyl ether monoacetate Diethylene glycol monoethyl ether Diethylene glycol diethyl ether Ethylene glycol monophenyl ether Veratrole (1,2-dimethoxybenzene) Eugeneol methyl ether Hydroquinonedimethyl ether The metal images, e.g., images made of palladium or any metal more easily oxidized (i.e., has a standard oxidation potential more positive than -0.98 volt) (e.g., silver, nickel, copper, iron, palladium, zinc, lead, tin, etc.) in hyrophilic colloid layers containing a dispersion of one or more of my organic oils are used to advantage in the preparation of my hight density formazan dye images. The metal images are produced in the presence of my organic oils by any conventional image-forming methods and especially by photographic methods using chemical or physical developing-out photographic elements and processes.

Silver images, for example, are produced advantageously by developing latent images in light-sensitive silver salt dispersions in my novel photographic hydrophilic colloid emulsion in the presence of a dispersion of at least one of my organic oils. Any of the silver halide emulsions, e.g., silver chloride, silver bromide, silver iodide, silver chlorobromide, silver bromoiodide, silver chlorobromoiodide, etc., as well as other light-sensitive silver salts dispersed in gelatin or gelatin substitute and always in the presence of a dispersion of at least one of my organic oils are used to advantage. These emulsions are advantageously coated on any of the usual supports, including paper, glass, polymeric films, e.g., cellulose acetate film, polyvinyl acetal film, polystyrene film, polypropylene film and other polyolefin films, polycarbonate film, polyethylene terephthalate film and other polyester films.

'Hydrophilic colloids used to advantage in my photographic elements include gelatin, colloidal albumin, a cellulose derivative, or a synthetic resin, for instance, a polyvinyl compound. Some colloids which may be used are polyvinyl alcohol or a hydrolyzed polyvinyl acetate as described in Lowe, U.S. Pat. 2,286,215, issued June 1 6, 1942; a far hydrolyzed cellulose ester, such as, cellulose acetate hydrolyzed to an acetyl content of 1926% as described in Lowe et al., U.S. Pat. 2,327,808, issued Aug. 24, 1943; a water-soluble ethanolamine cellulose acetate as described by Yutzy, U.S. 2,322,085, issued June 15, 1943; a polyacrylamide having a combined acrylamide content of 30-60% and a specific viscosity of 0.25-1.5 or an imidized polyacrylamide of like acrylamide content and viscosity as described in Lowe et al., U.S. Pat. 2,541,- 474, issued Feb. 13, 1951; zein as described in Lowe, U.S. Pat. 2,563,791, issued Aug. 7, 1951, a vinyl alcohol poly mer containing urethane carboxylic acid groups of the type described in Un-ruh et al., U.S. Pat. 2,768,154, issued Oct. 23, 1956, or containing cyano-acetyl groups, such as, the vinyl alcohol-vinyl cyano-acetate copolymer as described in Unruh et al., U.S. Pat. 2,808,331, issued Oct. 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 Illingsworth ct al., U.S. Pat. 2,852,382, issued Sept. 16, 195 8.

The emulsions used in the photographic elements of my invention can be chemically sensitized by any of the accepted procedures. The emulsions can be digested with naturally active gelatin, or sulfur compounds can be added, such as those described in Sheppard, U.S. Pat. 1,574,944, issued Mar. 2, 1926; Sheppard et al., U.S. Pat. 1,623,499, issued Apr. 5, 1927; and Sheppard et al., U.S. Pat. 2,410,689, issued Nov. 5, 1946.

The emulsions can also be treated with salts of the noble metals, such as ruthenium, rhodium, palladium, iridium and platinum, as described in Smith et al., U.S. Pat. 2,448,060, issued Aug. 31, 1948 and as described in Trivelli et al., U.S. Pats. 2,566,245 and 2,566,263, both issued Aug. 28, 1951.

The emulsions can also be spectrally sensitized with cyanine and merocyanine dyes, such as those described in Brooker, U.S. Pats. 1,846,301 and 1,846,302, both issued Feb. 23, 1932; and 1,942,854, issued Jan. 9, 1934; White, U.S. Pat. 1,990,507, issued Feb. 12, 1935 Brooker and White, U.S. Pats. 2,112,140, issued Mar. 22, 1938; 2,165,338, issued July 11, 1939; 2,493,747, issued Jan. 10, 1950; and 2,739,964, issued Mar. 27, 1956; Brooker et al., US. Pat. 2,493,748, issued Jan. 10, 1950; Sprague, U.S. Pats. 2,503,776, issued Apr. 11, 1950 and 2,519,001, issued Aug. 15, 1950; Heseltine et al., U.S. Pat. 2,666,761, issued J an. 19, 1954; Heseltine, U.S. Pat. 2,734,900, issued Feb. 14, 1956; VanLare, U.S. Pat. 2,739,149, issued Mar. 20, 1956; and Kodak Limited, British 450,958, accepted July 15, 1936.

The emulsions may also contain speed-increasing compounds of the quaternary ammonium type of Carroll, U.S. Pat. 2,271,623, issued Feb. 3, 1942; Carroll et al., U.S. Pat. 2,288,226, issued June 30, 1942; and Carroll et al., U.S. Pat. 2,334,864, issued Nov. 23, 1943; and the polyethylene glycol type of Carroll et al., U.S. Pat. 2,708,162, issued May 10, 1955.

The emulsions can also be chemically sensitized with gold salts as described in Waller et al., U.S. Pat. 2,399,- 083, issued Apr. 23, 1946, or stabilized with gold salts as described in Damschroder, U.S. Pat. 2,597,856, issued May 27, 1-952; and Yutzy et al., U.S. 2,597,915, issued May 27, 1952. Suitable compounds are potassium chloroaurite, potassium aurithiocyanate, potassium chloroaurate, auric trichloride and 2-aurosulfobenzothiazole methochloride.

Latent images produced by the usual image-exposure techniques with infrared, visible light, ultraviolet, X-rays, etc., are advantageously developed to silver images by treating with an aqueous alkaline solution of a developing agent such as hydroquinone, a catechol, a pyrogallol, an aminophenol, a 3-pyrazolidone, etc., followed by fixing in a fixing bath containing an alkali metal thiosulfate, thiocyanate or thiourea.

Nickel images, for example, are produced by physically developing an exposed photo-sensitive material of the type containing a layer of palladium nuclei on a Ti0 coated support, described in Examples 15 and 17 on pages 18 and 19 of Belgian Pat. 718,019.

Any water-soluble difiusible T-salt is used advantageously according to my invention to convert the metal image to a corresponding formazan dye image. Included among the useful T-salts are those having the formulas:

N wish-1 captophenyl group, a nitrophenyl group, etc.), a naphthyl group (e.g., u-naphthyl, B-naphthyl, a carboxynaphthyl group, a hydroxynaphthyl group, a sulfonaphthyl group, a mercaptonaphthyl group, an aminouapht hyl group, a carbamylnaphthyl group, a sulfonamidonaphthyl group, a sulfamylnaphthyl group, a nitronaphthyl group, etc.) etc., and a heterocyclic group, preferably containing from to 6 atoms, and preferably containing hetero atoms, such as nitrogen, sulphur, oxygen and selenium, such as, for example, a thiazolyl group, a benzothiazolyl group, an oxazolyl group, a benzoxazolyl group, a selenazolyl group, a benzoselenazolyl group, a benzimidazolyl group, a naphthimidazolyl group, a triazinyl group, a pyrimidinyl group, a pyridyl group, a quinolyl group, a thienyl group, etc; R represents any of the groups represented by R and, in addition, represents an alkyl group (e.g., methyl, butyl, hexyl, dodecyl, mercaptomethyl, mercaptoethyl, etc.) etc., hydrogen, hydroxyl, carboxyl, a salt of a carboxyl group (e.g., an alkali metal salt or ammonium salt), a carboxy ester group (e.g., methoxycarbonyl, ethoxycarbonyl, phenoxycarbonyl, etc.), an amino group (e.g., amino, ethylamino, dimethylamino, anilino, etc.), a carbamyl group (e.g., carbamyl, ethylcarb-amyl, dimethylcarbamyl, phenylcarbamyl, etc.), sulfo, a salt of a sulfo group (e.g., an alkali metal salt), a sulfoamido group (e.g., methylsulfonamido, butylsulfonamido, phenylsulfonamido, etc.), a sulfamyl group (e.g., sulfamyl, methylsulfamyl, butyl sulfamyl, phenylsulfamyl, etc.), the mercapto group, the nitro group, or any other substituent cited as being present in this position of the formazan or the tetrazolium salt in Chem. Rev. 55, 355- 483 (.1955); and the substituents R and R advantageously contain an electron-sharing group capable of forming metal chelates or complexes, such as primary, secondary and tertiary amino, substituted amino, oxime, thioether, keto, thioketo, hydroxyl, mercapto, carboxyl, sulfo, phospho, alkoxy groups or complexes; X" represents ananion (e.g., chloride, iodide, bromide, thiocyanate, thiosulfate, sulfate, paratolulenesulfonate, methylsulfate, ethylsulfate, nitrate, acetate, perchlorate, perborate, sulfite, hydroxide, carbonate, etc.); D represents a divalent aromatic group (e.g., a phenylene, diphenylene, naphthalene, phenylmet'hylphenyl, etc.); and E rep resents a divalent group such as an alkylene group (e.g., methylene, ethylene, propylene, butylene, etc.), an arylene group (e.g., phenylene naphthalene, diphenylene, etc.), an arylene alkylene group, for example, a phenylene al-kylene group (e.g., phenylene methylene, phenylene butylene, phenylene hexylene, etc.), a naphthylene alkylene group (e.g., naphthylene methylene, naphthylene butylene, naphthylene propylene, etc.), etc.; q represents an integer of from 1 to 5. #Solutions of T-salts in which at least one of R R and R represents a thiazolyl nucleus, a benzothiazolyl nucleus, a naphthothiazolyl nucleus, a benzimidazolyl nucleus, a naphthimidazolyl nucleus, or a pyridyl nucleus and/or X represents a chloride ion, a bromide ion, an iodide ion, a thiocyanate ion or a thiosulfate ion do not require a separate metal ion complexing agent for use in converting our metal images to formazan dye images; however, a separate complexing agent is used if additional complexing activity is desired.

Tetrazolium salts used to advantage according to my invention include the following representative compounds:

TABLE-Continued No. T-salt name 8 2,5-diphenyl-3-(pyrid-3-yl)-2H-tetrazolium chloride.

9 2-(4-ch1orophenyl)-3-(2-chlorophenyl)-5-(pyrid-2-y1)-2H- tetrazolium iodide.

10 2,3-diphenyl-5-(benzimidazol-Z-yl)-2H-tetrazollum chloride.

11... 2,3-di(4-bromophenyl)-5-(benzothiazol-2-yl)-2H-tetrazolium chloride. 2-(beuzothiazol-2-yl)-3-phenyl-5-(2-phenyltriezol-5-yl)- 2H-tetrazo1i um chloride.

13 2,2-di(benzotniazol-Z-yl)-3,3-diohenyl-5,5-diethylene di-(2H-tetrazolium chloride).

14... 2,2-di(benzothiazol-2-yl)-3,3-diphenyl-5,5'-di-i,6-hexylene di-(2H-tetrazolium chloride).

15... 2,2-di (thiazol-fZ-yl)-3,3-dipheny1-5,5-dipheny1ene-di- (ZH-tetrazolium iodide).

17 3,3-di (thiazol-2-yl)-5,5-di (thien-Z-yl)-2,2-di-p-(3,3-dimethoxydiphenylene) di-(ZH-tetrazolium chloride).

18 3,3,5,5-tetrapheny1-2,2-syn-p-phenylthiourea di-(2H- tetrazolium bromide).

20 2-(benzothiazol-2-yl)-5-(4-acetamidophenyl)-3(4- phenylazophenyl) -2H-tetrazoli1nn bromide.

21 2-(benzothiazol-2-yl)-3-(4-methoxyphenyl)-5-phenyl-2H- tetrazolium bromide.

22-.. 2-(4,E-dimethylthiazol-Z-yl) -3,5-dipheny1-2H-tetrazolium bromide.

23 2- (-chlorophenyl) -3-(2-chlorophcnyl) -5- (pyri d-2-yl) -2H- tetrazolium iodide.

24 2-(benzimidazol-2-yl)-5-(2-chlorophenyl)-3-phenyl-2IEI- tetrazolinm chloride.

25 3,5-diphenyl-2-(pyrid-2-yl)-2]E[-tetrazoliu.rn chloride.

26 3-(benzothiazol-2-yl)-5-phenyl-2-(triazin-Z-yl)-2H- tetrazolium chloride.

27 2,5-di(beuzothiazol-Zyl)3-(p-hydroxyphenyl)-2H- tetrazolium chloride.

28 3-(o-carboxyphenyl)-5-methyl-2-(4-phenylthiazol-Z-yl)- 2H-tetrazolium bromide.

29 3-(o-carboxyphenyl)-5methyl-Z-(naphthathiazol-Z-yl)- ZH-tetrazolium chloride.

30.--.. 2- (b enzothi azol-Z-yl) -3-(p-sulfa.mylphenyl) -5-hexyl-2H- tetrezolium chloride.

31 2,3-di(benzothiazol-2-yl) -5-dodecyl-2H-tetrazolium chloride.

32. 2,3-di (pyrid-Z-yl)-5-hydroxy-2Htetrazol.um chloride.

33- 2,3-di(benzimidazol-Z-yl)-5 mercapto 2H-tetrazolium bromide.

84. fi-arkrxilin o( 13(benzothiazp l-2-yl) -2phenyi-2H-tetrazolium c on e.

35 fi-benzamido-3-(4,5-dimethylthiazo1-2-yl)2-phenyl-2H- tetrazolium chloride 39 2-(benzothiazol-2-yl)-5-(Z-chlorophenyl)-3-(4-nitrophenyl)- 2H-tet'razelium bromide.

40 2-(benzothiazol-2-yl)-5-phenyl-3-(4-to1yl)-2H-tetrazolium bromide.

41 2-(benzothiazol-2-yD-3-(4-chloropheny1)-5-phenyl-2H- tetrazolium bromide.

42 Z-(benzothiazol-Z-yl)-5(4-chlorophenyl)-3 (4'nitrophenyl) ZH-tctrazolium bromide.

43 3-gaenzoghi azol-2-yl) -2-phenyl-5-(quinol-Z-yl) -2H-tetrazolium 44 B-(benzothiazol-Z-yl)-2-phenyl-5-propyl-2H-tetrazolium iodide.

45 B-(benzothiazol-Z-yl) -2-phenyl-5-(pyrimidine-2-y1) -2H- tetrazolium bromide.

46 2-(naphthimidazol-2-yl)3,5-diphenyl-2H-tetrazolium acetate.

47- B-(benZirnidaZOLZ-yl)-2,5-diphenyl-ZH-tetrazolium nitrate.

48- 3,5-diphenyl-2-(pyrid-2-yl)-2H-tetrezolium sulfate.

49 2,5-dipdhenyl-3(4,5-dimethy1thiazol-2-vl)-2H-tetrazolium iodi e.

50 2,3-diphenyl-2Htetrazolium thiosulfatc.

51 2,B-diphenyl-ZH-tetrezoliurn thiocyanate.

52 2,3,5-triphenyl-2H-tetrazolium chloride.

53 2,3-diphenyl-2H-tetrazolium chloride.

54 2,3-diphenyl-2H-tetrazolium iodide.

55 2,3-diphenyl-5-methyl-2H-tetrazolium chloride.-

56 2,3-diphenyl-5-methyl-ZH-tetrazolium bromide.

57 3-(ril-fiyii'oxyphenyl)-5-methyl-Z-phenyl-ZH-tetrazolium c or e.

58 3-(ril-isulfamylphenyl)-5-mcthyI-2-phenyl-ZH-tetrazolium c o e.

59 2,3-diphenyl-5-ethyl-2H-tertazo1ium chloride.

60 3(-pk-1slu1a1mylphenyl)-3-phenyl-5-propyl-ZH-tetrazolium c or. e.

61 2,3-diphenyl-5-isobutyl-ZH-tetrazolium chloride.

62- I 2,S-diphenyl-fi-n-hexyl-2H-tetrazolium chloride.

63 2,3-diphenyl fi-dodecyl-2Htetrazoliu.m chloride.

64 2,3-diphenyl-5-hydroxy-ZH-tetrazolium betaine.

65 2,3-diphenyl-5-hydroxy-2H-tetrazelium chloride.

66 2,3-diphenyl-5-mereapto-2H-tetrazolium betaine.

67 5-amino-2,3-dipheny1-2H-tetre.zolium chloride.

68 5-benzamido-2,3-diphenyl-2H-tetrezolium chloride.

69 B-benzamido-2,3-diphenyl-2H-tetrazolium betaine.

70 5-cyano-2,3-diphenyl-2H-tetrazollum chloride.

71 5-carboxy-2,3-diphenyi-2H-tetrazolium betaine.

72 E-carboxy-2,3-diphenyl-ZH-tetrazolium chloride.

73 5-carboxy-2,3-diphenyl-2H-tetrazolium nitrate.

74 5-ethoxycarbonyl-2,3-diphenyl-2H-tetrazolium chloride.

76 23-12111-(pdethoxyphenyl)-5-ethoxycarbonyl-2H-tetrazolium c or e.

77- 5-acetyl-2,3-diphenyl-2H-tetrazolium chloride.

78 5-benzoyl-2,3-diphenyl-2H-tetrazolium chloride.

79 2,5-dipheuyl-3-(p-tolyl)-2H-tetrazolinm bromide.

80 2,5-dipheny1-3-(p-isopropylphenyl)-2H-tetrazolium bromide.

TABLEContlnued T-salt No. T-salt name 81 2,5-dipheny1-3-(p-n-dodecylphenyl)2H-tetrazolium iodide. 82 2,5-diphenyl-3-(p diphenyl)-2H-tetrazoluim chloride.

2,3-diphenyl-5-(p-diphenyl)-2H-tetrazolium chloride.

84 2,5-diphenyl-3-(p-chlorophenyl)-2H-tetrazolium iodide.

85 2,5-diphenyl-s-(iodophenyl)-2H-tetrazolium chloride.

86- 3,5-d1(p-bromophenyl)-2-phenyl-2H-tetrlazolium chloride.

87 5-(p.bromophenyl)-2-phenyl-3-(2,4,6-tr1bromophenyl)-2H- tetrazolium bromide.

88 B-(p-lodophenyl)-2-(p-nitrophenyl)-5-phenyl-2H-tetrazolium 1O chloride.

89 3-(p-hydroxyphenyl)-5-(p-nitrophenyl)-2-phenyl-2H-tetrazoliuin chloride.

90 5-(8,4dimethoxypheny1)-3-methoxyphenyl-2-phenyl-2H- tetrazolium iodide.

5-(3-methoxyphenyl) -3-(a-triiiuoromethylphenyl)-2-phenylzH-tetrazolium acetate.

92 5-(4-eyanophenyl)-2,B-diphenyl-ZH-tctrazolium chloride.

- 5-(fur-2-yl)-2,3-dlphenyl-2H-tetrazollum chloride.

.. 2,3-diphenyl5-n1tro-2H-tetrazolium chloride.

107 2,3-diplienyl-5-sulfo-2H-tetrazolium chloride.

108- 2,3-diphenyl-5-sulfonamido-ZH-tetrazolium chloride.

109 2,2'fi,figegraphenyl-5,5-diethylene di-(2H-tetrazolium 111 2,2h?,3fietraphenyl-5,5-di-p-phenylene dl-(2H-tetrazo1ium c or 112 5,5'-dimethyl;3,3-diphenyl-2,2'-di-p-diphonylene di-(ZH- tetrazolium ,(lllOlldB) 113 3,3,5,5-tetrap enyl-2,2'-di-p-(3,3-dimethyl-diphenylene) di-(ZH-tetrazolium chloride).

114 3,3,5,5-tetraphenyl-2,2-syn-p-phenylthiourea di-(ZH- tetrazolium chloride).

115 3,3',5,5-tetraphenyl-2,2-syn-p-phenyl sulfoxide di-(2H- tetrazolium chloride) 116 2,2',3,3-tetraphenyl-5,5'-p-phenylene ethylene di-(ZH- tetrazolium chloride.

These tetr'azolium salts are well known in the art, most of them having been described in literature references such as Chemical Revue 55, published bi-monthly 5 for the American Chemical Society by the Williams and Wilkins Co., Baltimore, 1955. Any tetrazolium salts that are not shown specifically in the prior art are advantageously prepared by methods well known in the art.

When aqueous solutions of my T-salts are brought into contact with metal images of palladium or any metal more easily oxidized (i.e., has a standard oxidation potential more positive than -0.98 volt) (e.g., silver, nickel, copper, iron, palladium, zinc, lead, tin, etc.), the metal is oxidized to its ion and the T-salt is reduced to produce the corresponding formazan dye. The following equation shows a typical reaction:

Formazan Dye Any ligand that is a silver complexing agent is advantageously used that produces a silver ion complex.

Included among the ligands used to advantage are the following typical examples: water-soluble thiosulfates (e.g., sodium thiosulfate, potassium thiosulfate, ammonium thiosulfate, etc.), thiourea, ethylenethiourea, a water-soluble thiocyanate (e.g., sodium thiocyanate, potassium thiocyanate, ammonium thiocyanate), a watersoluble sulfur containing dibasic acid. Water-soluble diols used to advantage include those having the formula:

wherein r is an integer of from 2 to 13; the Zfs represent oxygen or sulfur atoms such that at least one-third of the Z atoms are sulfur and there are at least two consecutive Z s in the structure of the compound which are sulfur atoms. The diols advantageously used are also included in comp ounds having the formula:

wherein X and X represent oxygen or sulfur, such that when X represents oxygen, X represents sulfur and when X represents sulfur, X represents oxygen; 0, d, e, f and g each represent an integer of from 1 to 15, such that the sum of c+d+e+f+g represents an integer of from 6 to 19, and such that at least one third of the total of all the X s plus all the X s represent sulfur atoms and at least two consecutive X s and/or X s in the structure of the compound are sulfur atoms.

Typical diols include the following:

(1) 3,6-dithia-l,8-octanedio1 HOCH CH SCH CH SCH CH OH (2) 3,6,9-trithia-l,1 l-undecanediol HOCH CH SCH CH SCH CH SCH CH OH (3) 3,6,9,12-tetrathia-1,14-tetradecanediol HO (CH CH S CH CH OH (4) 9-oxa-3 ,6,9,12,15-tetrathia-1,17-heptadecanediol HO (CH CH S CH CH O (CH CH S) CH C-H OH (5) 9, 12-dioxa-3,6, 15,18-tetrathia-1,20-eicosanediol HO(CH CH S) 2 (CH CH O (CH CH S CH CH O-H (6) 3,6-dioxa-9,12-dithia-l,14-tetradecanediol HO(CH CH O 2 (CH CH S) CH CH OH (7) 3,12-dioxa-6,9-ditl1ia-1,l4-tetradecanediol 'HOCH CH O (CH CH S) CH CH OCH CH OH (8) 3,l8-dioxa-6,9,12,1S-tetrathia-1,20-eicosanediol HOCH CH O CH CH S) CH CH O CH CH OH (9) 12,l8-dioxa-3,6,9,15,21,24,27-heptathia-1,29-nonacosanediol l0) 6,9,15,18-tetrathia-3,12,2l-trioxa-1,23-tricosanedi0l HOCH CH O (CHzCHgS) CH CH O (CH CH S) CH CH OCH CH OH Water-soluble sulfur containing dibasic acids used to advantage include those having the formula:

HOOCCH (SCH CH SCI-I COOH in which 1 represents an integer of from 1 to, and includmg, 3 and the alkali metal and ammonium salts of said acids. Typical illustrative examples include:

ethylene-bis-thioglycolic acid HOOCCH SCH CH SCH CO0H 3,6,9-trithiahendecanedioic acid HOOCCH (SCH CH SCH COOH 3,6,9,l2-tetrathiatetradecanedioic acid 13 nooccnnscu cun scn coon ethylene-bis-thioglycolic acid di-soclium salt ethylene-bis-thioglyco1ic acid di-potassium salt ethylene-bis-thioglycolic acid di-ammonium salt 3,6,9-trithiahendecanedioic acid di-sodium salt 3,6,9,12-tetrathiatetradecanedioic acid di-sodium salt The concentration of the T-salt and the ligand in my compositions can be varied considerably, with an operable range of concentrations extending from the solubility limit of the T-salt and the solubility limit of the ligand down to a minimum concentration where the overall reaction potential for the specific T-salt, ligand and specific metal image just remains positive, usually above +0.01 volt. The operable concentration ranges and the preferred concentration ranges are readily determined by methods well known in the art and need not be discussed further.

The following examples are included for a further understanding of my invention:

EXAMPLE 1 Dispersions identified as A, B, C and D are made having the compositions indicated below for high-boiling crystalloidal onganic oils A, B, C and D, respectively, as identified below:

Organic oil g 44.0 10% gelatin solution g 220.0 Alkanol B c 4.4

Mill 5 times, then add distilled Water to a total weight of 300 g. The average diameter of the oil particles is about 1 11.

Each of the dispersions A, B, C and D are blended with separate portions of a gelatino silver bromoiodide emulsion and each of these blends is further blended with a formaldehyde solution just before coating on each side of a polyethylene terephthalate support using the coating technique dual melting as described in US. Pat. 2,912,343 so that there is coated on each side of the support per square foot 175 mg. of silver, 134 mg. of gelatin and 89 mg. of organic oil. Each coating is identified according to the identification of the organic oil used. Control Coating X is made just like the other coatings, but by substituting for the organic oil dispersion suflicient gelatin so that the control coating has in each square foot on each side of the support 134 mg. of gelatin and 175 mg. of silver. After the coatings are dried, strips of the coatings are sensitometrically exposed to light with a sensitometer and processed at 35 C. with six minutes development in a conventional aqueous alkaline developer solution containing p-methylaminophenol and hydroquinone, five minutes fixing in the fixing bath described later in this example, washing and drying. The dried and processed strips are each cut in half so that each half of a strip contains identical silver images. One-half of each of the strips are given no further treatment while the other half are given the following additional process steps at a temperature of 35 C.:

The T-salt bath has the composition:

2,3,5-triphenyl-2H-tetrazoliumchloride g 15 Thiourea g 15 Sodium thiosulfate g 50 Distilled water to make 1 l.

The fixing bath has the composition:

Sodium thiosulfate g 2400 Sodium sulfite (desiccated) g 15.0 Acetic acid, 28% cc 48.0 Boric acid crystals g 7.5 Potassium alum g 15.0

Water to 1.0 l.

The densities of the silver images in the halves of the strips of processed Coatings X, A, B, C and D that were not given the T-salt bath treatment are measured with a densitometer and from these data the -D and fog values are recorded and the gamma and relative speed values are computed with the relative speed of the Control Strip X arbitrarily set at and the relative speeds for Strips A, B, C and D related to the relative speed set for the control. The densities of the silver plus formazan dye images in the other half of the strips of processed Coatings X, A, B, C and D that were given the T-salt bath treatment are measured with a densitometer and from these data the D and fog values are recorded and the gamma and relative speed values are computed with the relative speed values related to the relative speed of 100 set for Control Coatings X (without T-salt bath treatment). The percent increase in relative speed, 7 and D produced in Strips X, A, B, C and D by treatment with the T-salt bath are tabulated in Table II:

TABLE II Percent increase in- Rel. speed '7 from Dmux from Organic from T-salt T-salt bath T-salt bath oil bath treatment treatment treatment None 23 20 23 A 41 91 81 B 54 100 103 C 68 69 D 58 41 The data in Table III show very substantially higher percent increases in D and 7 from treatment of my silver images in the presence of organic oils A, B, C and D with the T-salt bath compared to treatment of the silver image in the control strip containing no organic oil. Strips A and B with organic oils A and B, respectively, have substantially higher percent increase in relative speed from treatment with the T-salt bath than is shown with the same T-salt bath in Control Strip X without any organic oil. An analysis is made of the amount of silver in each of the Strips X, A, B, C and D, both those strips that were given the T-salt bath treatment as well as those without the T-salt bath treatment. The decrease in silver caused by T-salt bath treatment in Coatings X, A, B, C and D is calculated and recorded in Table III. The increase in 13 density produced by T-salt bath treatment is determined for each coating and recorded in Table III. The change in covering power==Increase in D x 10 /L0ss in Ag produced by the T-salt bath treatment is calculated and recorded in Table III for each coating.

TABLE III Covering Loss in Increase in power in- Ag from Dmnx from crease from Organic T-salt bath T-salt bath T-salt bath Coating oil treatment treatment treatment X.- None.--- 79 0.28 3.5 A 142 1.01 7. 1 B 1.26 6. 5 169 0. 84 5. 0 83 0.48 5.8

The data in Table III show that the addition of my organic oils A, B, C and D to my photographic emulsions increases the amount of silver utilized in the conversion 15 of silver metal image to formazan dye image resulting in a very substantial increase in optical density and in covering power. The presence of Organic Oil A in my Coating A results in twice the increase in covering power produced by the same T-salt bath treatment in Control Coating X without an organic oil.

EXAMPLE 2 Example 1 is repeated exactly, except that the Coatings X, A, B, C and D are sensitometrically exposed with X-rays instead of light to produce comparable latent images. The results obtained are identical to those obtained in Example 1.

EXAMPLE 3 Example 1 is repeated, except that the T-salt bath used is 24 C. instead of 35 C. and the treatment time increased enough to produce a silver plus formazan dye image in the Control Coating X that is equivalent to the silver plus formazan dye image produced in Control Coating X in Example 1. The data show that treatment with the T-salt bath produces in my elements improvements in covering power, D 'y and speed that are similar to those obtained in Example 1.

EXAMPLE 4 Thirteen sets of strips of Coatings A, B, C and D of my invention and Control Coating X are prepared, sensitometrically exposed, developed, fixed, washed, dried and slit, all as described in Example 1. One-half of each of these processed strips is given no further treatment and the other half is presoaked, treated with T-salt solution bath, fixed, washed and dried as described in Example 1, except that each set of Strips A, B, C, D and X are put through a T-salt bath of Example 1, but in which the 2,3,5-triphenyl-2H-tetrazolium chloride (of Example 1) is replaced by 15 g. of a different T-salt from the following list:

2,3-dipheny1-5- (pyrid-Z-yl -2H-tetrazolium bromide 2,3-diphenyl-5- (benzoxazol-Z-yl) -2H-tetrazolium chloride 2,3 -di (4-bromophenyl -5- (benzothiazol-Z-yl) -2H- tetrazolium chloride 5 ,5 '-dimethyl-3 ,3 '-diphenyl-2,2'-di (p-diphenylene di (ZH-tetrazolium chloride) T-Salt Name 2,2',3,3-tetraphenyl-S,5-diethylene-di(2H- tetrazolium chloride) 2,3'-diphenyl-ZH-tetrazolium chloride 3- (p-hydroxyphenyl) -5-methyl-2H-tetrazolium chloride 2,3-diphenyl-5-dodecyl-2H-tetrazolium chloride 2,3-diphenyl-S-hydroxy-ZH-tetrazolium chloride 5-amino-2,3-diphenyl2H-tetrazolium chloride 5-carboxy-2,3-diphenyl-2H-tetrazolium chloride S-benzamido-2,3-diphenyl-2H-tetrazolium chloride 5-ethoxycarbonyl-2,3-diphenyl-2H-tetrazolium chloride D 7, relative speed and covering power data are obtained for each half of the thirteen sets of Coatings A, B, C, D and X, as described in Example 1. The data for each set of coatings show that my Coatings A, B, C and D give substantially the same increases in covering power, D 'y, and relative speed from treatment in the T-salt baths using the T-salts of this example as are obtained for Coatings A, B, C and D, respectively, from the treatment with the T-salt bath described in Example 1.

EXAMPLE 5 Example 1 is repeated, but the dispersions of organic oil are prepared so that the average diameters of the oil particles is about 2,11. instead of l,u.. Improvements in cover- 1 6 ing power, D 'y, and relative speed, similar to those in Example 1, are obtained.

EXAMPLE 6 Example 1 is repeated, except that the formulation of the organic oil dispersions is altered so that the weight ratio of organic oil to gelatin in the coated elements is about 1:0.1 instead of the 1:15 weight ratio used in Example 1. The results show that these elements provide useful improvements in image covering power, D 'y, and relative speed over the control without any organic oil when developed and fixed silver images in these elements are treated with the T-salt bath.

EXAMPLE 7 Example 1 is repeated, except that the formulation of the organic oil dispersions is altered so that the weight ratio of organic oil to gelatin is about 1:30 instead of 1:1.5, as in Example 1. The results show that these elements of my invention provide useful improvements over the control when treated with the T-salt bath.

EXAMPLE 8 Example 1 is repeated, except that instead of the organic oils used in Example 1, the other phosphate esters and sulfonate esters listed on page 10 of this application, the organic esters listed on pages 11 and 12, the amides, the imides, the ketones, the alcohols, all listed on page 12, and the ethers listed on page 13, are used as the organic oil. Silver images in my elements containing dispersions of these organic oils are converted to silver plus formazan dye images with substantially greater increases in covering power by treatment with the T-salt bath than the increase in covering power produced in silver images in the control elements by the same treatment.

Similarly, it can be shown that elements of my invention containing dispersions of still other organic oils of Formulas I through XII will give greater increases in image covering power than a corresponding control when metal images such as silver, nickel, copper, iron palladium, zinc, lead, tin, etc. are treated with a T-salt bath containing a T-salt and a metal complexing agent.

Similarly, it can be shown that any of my photographic elements, such as are described in Example 1, are advantageously treated with T-salt baths using any of the specific T-salt Numbers 1 through 117 in my process to produce silver plus formazan dye images having substantially higher covering power than the silver plus formazan dye images produced in a control element containing none of my dispersed organic oil.

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

I claim:

1. In the process of replacing at least a portion of a photographic metal image in a hydrophilic colloid binder layer with a formazan dye image, wherein said metal image reduces a tetrazolium salt to form said formazan dye and a metal complexing ligand forms a metal complex, the improvement wherein said replacement of said metal image with said formazan dye image is conducted in a hydrophilic colloid binder layer containing a dispersion of at least one high boiling, substantially colorless, crystalloidal, organic oil having molecules that contain at least one polar group selected from the class consisting of an ester group, an amide group, an imide group, a ketone group, a hydroxyl group, an oxygen ether group and a halogen atom.

2. The process of claim 1 in which said binder comprises gelatin containing said organic oil as dispersed particles having diameters in the range up to about 2 3. The process of claim 1 in which said binder comprises gelatin containing a dispersion of said organic oil 17 in which the ratio of said oil to said gelatin is in the range of from about 1:0.1 to about 1:30.

4. In the process of replacing at least a portion of a photographic silver image in a hydrophilic colloid binder layer with a formazan dye image, wherein said silver image reduces a tetrazolium salt to form said formazan dye and a metal complexing ligand forms a metal complex, the improvement wherein said replacement of said silver image with said formazan dye image is conducted in a hydrophilic colloid binder layer containing a dispersion of at least one high-boiling, substantially colorless, crystalloidal, organic oil selected from those having the formulas:

wherein R R R R R and R each represent a member independently selected from the class consisting of hydrogen, halogen, an alkyl group, a phenyl group, an alkoxy group and a phenoxy group;

II. R2

g -ORQ R A wherein R and R are as defined previously and R represents a group selected from the class consisting of an alkyl group and an aryl group;

III. 0

R7-O R3 group and a group R and R are as defined previously and n represents an integer of from 2 to 3;

wherein R is as described previously; R represents a group selected from the class consisting of an alkyl group and an aryl group; Z represents a divalent group selected from the class consisting of CH=CH and -(CH2)mand m represents an integer from 1 to 10;

iii-0R o iii-O R0 wherein R and R are as defined previously, and R represents a member selected from the class consisting of hydrogen, an alkyl group, an alkoxy group and a halogen atom;

VII. Ru

wherein Z, R and R are as defined previously, and R and R each represent a member independently selected from the class consisting of hydrogen, an alkyl group, an aryl group, and nonmetallic atoms which, when taken together with the nitrogen atom, between them complete a 5- to 6-membered heterocyclic ring;

wherein R is as defined previously and D represents a divalent group selected from the class consisting of a (CH),, group, CH=CH-, a Brag group I a R group, a B; group io a 2 an integer of from 1 to 3, and R is as defined previously; X

-' p, 9 represents wherein R, is as defined previously and R represents a group selected from the class consisting of an alkyl group and an aryl group;

(XI) R -OH wherein R represents a group selected from the class consisting of an alkyl group and a 4-alkylaryl group; and

wherein R represents a group selected from the class consisting of an alkyl group, and a phenyl group; and R represents a group selected from the class consisting of an alkyl group and a phenyl group.

5. The process of claim 4 in which said binder comprises gelatin containing said organic oil as dispersed particles having diameters in the range of up to about 2 6. The process of claim 4 in which said binder comprises gelatin containing a dispersion of said organic oil in which the ratio of said oil to said gelatin is in the range of from about 1:0.1 to about 1:30.

7. In the process of replacing at least a portion of a photographic silver image in a hydrophilic colloid binder layer with a formazan dye image, wherein said silver image has a standard oxidation potential more positive than -0.=98 volt and reduces a tetrazolium salt to form said formazan dye and a metal complexing ligand forms a metal complex, the improvement wherein said replacement of said silver image with said formazan dye image is conducted in a hydrophilic colloid binder layer containing a dispersion of at least one high-boiling, substantially colorless, crystalloidal, organic oil selected from those having the formula:

wherein R R R R R and R each represent a member independently selected from the class consisting of hydrogen, halogen,= an alkyl group, a phenyl group, an alkoxy group and a phenoxy group.

8. In the process of replacing at least a portion of a photographic silver image in a hydrophilic colloid binder layer with a formazan dye image, wherein said silver image reduces a tetrazolium salt to form said formazan dye and a metal complexing ligand forms a metal complex, the improvement wherein said replacement of said silver image with said formazan dye image is conducted in a hydrophilic colloid binder layer containing a dispersion of at least one high-boiling, substantially colorless, crystalloidal, organic oil selected from those having the formula:

wherein R and R are each independently selected from the class consisting of an alkyl group and an aryl group, and R10 represents a member selected from the class consisting of hydrogen, an alkyl group, an alkoxy group and a halogen atom.

9. In the process of replacing at least a portion of a photographic silver image in a hydrophilic colloid binder layer with a formazan dye image, wherein said silver image reduces a tetrazolium salt to form said formazan dye and a metal complexin-g ligand forms a metal complex, the improvement wherein said replacement of said silver image with said formazan dye image is conducted in a hydrophilic colloid binder layer containing a dispersion of at least one high-boiling, substantially colorless, crystalloidal, organic oil selected from those having the formula:

R1; R1 /N wherein R represents a group selected from the class consisting of an alkyl group and an aryl group; R and R each represent a member independently selected from the class consisting of hydrogen, an alkyl group, an aryl group and nonmetallic atoms which, when taken together with the nitrogen atom, between them complete a to G-membered heterocyclic ring.

10. In the process of replacing at least a portion of a photographic silver image in a hydrophilic colloid binder layer with a formazan dye image, wherein said silver image reduces a tetrazolium salt to form said formazan dye and a metal complexing ligand forms a metal complex, the improvement wherein said replacement of said silver image with said formazan dye image is conducted in a hydrophilic colloid binder layer containing a dispersion of at least one high-boiling, substantially colorless, crystalloidal, organic oil selected from those having the formula:

R -OH wherein R represents a group selected from the class consisting of an alkyl group and a 4-alkylaryl group.

11. In the process of replacing at least a portion of a photographic metal image in a hydrophilic colloid binder layer with a formazan dye image, wherein said metal image reduces a tetrazolium salt to form said formazan dye and a metal complexing ligand forms a metal complex, the improvement wherein said replacement of said metal image with said formazan dye image is conducted in a hydrophilic colloid binder layer containing a dispersion of tricresyl phosphate with the weight ratio of tricresyl phosphate to gelatin being about 1:1.5.

12. In the process of replacing at least a portion of a photographic metal image in a hydrophilic colloid binder layer with a formazan dye image, wherein said metal image reduces a tetrazolium salt to form said formazan dye and a metal complexing ligand forms a metal complex, the improvement wherein said replacement of said metal image with said formazan dye image is conducted in a hydrophilic colloid binder layer containing a dispersion of di-n-butyl phthalate with the weight ratio of di-nbutyl phthalate to gelatin being about 1: 1.5.

13. In the process of replacing at least a portion of a photographic metal image in a hydrophilic colloid binder layer with a formazan dye image, wherein said metal image reduces a tetrazolium salt to form said formazan dye and a metal complexing ligand forms a metal complex, the improvement wherein said replacement of said metal image with said formazan dye image is conducted in a hydrophilic colloid binder layer containing a dispersion of diethyl lauramide with the weight ratio of diethyl lauramide to gelatin being about 1:15.

14. In the process of replacing at least a portion of a photographic metal image in a hydrophilic colloid binder layer with a formazan dye image, wherein said metal image reduces a tetrazolium salt to form said formazan dye and a metal complexing ligand forms a metal complex, the improvement wherein said replacement of said metal image with said formazan dye image is conducted in a hydrophilic colloid binder layer containing a dispersion of 2,4-di-tert-amylphenol with the weight ratio of di-tert-amylphenol to gelatin being about 1:15.

References Cited UNITED STATES PATENTS 2,949,360 8/1960 Julian 96-400 3,185,567 5/1965 Rogers 963 3,257,205 6/1966 Cassiers 9695 3,287,132 11/1966 Hunt 96-20 3,438,776 4/ 1969 Yudelson 96-28 3,503,741 3/1970 Wilson 9699 3,519,428 7/ 1970 Ishikawa 9695 3,576,634 4/1971 Woodward 96-66 FOREIGN PATENTS 884,494 12/ 1961 Great Britain 96-84 NORMAN G. TORCHIN, Primary Examiner J. R. HIGHTOWER, Assistant Examiner US. Cl. X.R. 9667