Photographic Sulfonamido Compounds and Elements and Processes Using Them

This invention relates to photography. In particular it relates to novel redox releasing compounds which can be used in photographic elements and processes to release dyes and other photographically useful groups as a function of silver halide development.

In the past a variety of different ballast groups have been attached in a non-coupling position to coupler materials for use in various color photographic processes, including conventional, subtractive color photographic processes as well as color diffusion transfer processes. The primary purpose for attaching a ballast group is to immobilize or render non-diffusible the coupler material so that it does not migrate into adjacent photographic layers where it is not needed or where it could undesirably interfere with other materials. Among the various ballast groups which have been found useful with coupler materials are N,N-disubstituted carbamoyl ballast groups. Representative prior art publications describing the use of disubstituted carbamoyl substituents for various phenolic and naphtholic couplers include U.S. Pat. No. 2,498,466 issued Feb. 21, 1950; U.S. Pat. No. 3,458,315 issued July 29, 1969; U.S. Pat. No. 3,476,563 issued Nov. 4, 1969; U.S. Pat. No. 3,591,383 issued July 6, 1971; U.K. Pat. No. 1,038,331 published Aug. 10, 1966; U.S. Pat. No. 3,148,062 issued Sept. 8, 1964; and U.S. Pat. Nos. 3,227,550 through 3,227,552 all issued on Jan. 4, 1966.

More recently, a new, improved color diffusion transfer photographic process has been discovered which does not employ coupler materials, but which, in accord with certain preferred embodiments thereof, employs nondiffusible compounds which are alkali-cleavable upon oxidation to thereby release a diffusible dye or dye precursor or another photographically useful group. These compounds have come to be known as redox releasing compounds and dye redox releasing compounds. This new color diffusion transfer process and materials useful therewith are described in Fleckenstein et al., Published U.S. patent application Ser. No. B351,673 dated Jan. 28, 1975. Additional useful materials and processes are described in Research Disclosure, Vol. 151, November 1976, Items 15157 and 15162. (Research Disclosure is published by Industrial Opportunities, Ltd., Homewell Havant, Hampshire P09 1EF, U.K.) One useful class of compounds described in U.S. patent application Ser. No. B351,673 are ballasted dye-releasing sulfonamido compounds, including sulfonamidophenols and sulfonamidoanilines.

As described in U.S. patent application Ser. No. B351,673 the ballast group which is attached to the various sulfonamido compounds described therein is an organic ballasting radical of such molecular size and configuration, including simple organic groups or polymeric groups, as to render the compound non-diffusible during development in an alkaline processing composition. A variety of specific individual ballast groups are suggested for use with the various sulfonamido compounds disclosed in the above-noted Fleckenstein et al. patent application.

Although the various ballasted sulfonamidophenol and sulfonamidoaniline compounds specifically disclosed in the Fleckenstein et al. patent application noted above have been found to be very useful, investigations have continued to further improve these compounds. In particular, it would be desirable to find compounds which are capable of providing, among other advantages, one or more of the following improvements: more rapid release of the photographically useful group (such as a dye or a photographic reagent) so that high quality images can be obtained in less time; a greater amount of the photographically useful group released per unit of developed silver halide emulsion; improved effectiveness in release capability with a broader range of cross oxidizing developing agent; ability to provide high quality color images over a broader range of pH conditions; increased photographic speed; and better image discrimination.

We have found that when the ballast group of a sulfonamido redox releasing compound is a N,N-disubstituted carbamoyl group, the compounds exhibit an unexpectedly high degree of efficiency with respect to the release of the photographically useful group and thus lead to desired improvements enumerated above.

Accordingly, this invention is directed to novel N,N-disubstituted carbamoyl sulfonamido redox releasing compounds, to photographic elements containing such compounds and to processes for forming images with elements containing such compounds.

In accordance with one embodiment of the present invention there is provided a photographic element comprising a support and at least one photosensitive silver halide emulsion layer having associated therewith a ballasted non-diffusible redox releasing compound having attached thereto through a sulfonamido group, a photographically useful group which is alkali-cleavable upon oxidation, the redox releasing compound being ballasted with an N,N-disubstituted carbamoyl group. Useful redox releasing compounds can be acyclic, carbocyclic or heterocyclic.

Acyclic redox releasing compounds useful in accordance with this invention can be represented by the structure: ##STR1## where:

m and n are integers of 1 or 2;

R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 independently represent a hydrogen or halogen atom or a cyano, amino, alkyl, alkoxy, aryl or acyl group; providing that R.sub.3 is ##STR2## when n and m are equal to 1, one of R.sub.3 or R.sub.4 is ##STR3## when one of m or n is equal to 2, and one of R.sub.3, R.sub.4, R.sub.5 or R.sub.6 is ##STR4## when m and n are both equal to 2; wherein R.sub.1 and R.sub.2 independently represent an aliphatic, alicyclic or aromatic group;

G represents an --OR.sub.5 group or an --NHR.sub.6 group, where R.sub.5 is hydrogen or a hydrolyzable moiety such as an acyl group and R.sub.6 is hydrogen, an alkyl group of 1 to 22 carbon atoms (e.g. methyl, ethyl, butyl, decyl, hexadecyl, etc.) or an --SO.sub.2 PUG moiety; and

PUG represents a photographically useful group.

Carbocyclic and heterocyclic redox releasing compounds useful in accordance with this invention can be represented by the structure: ##STR5## where:

R.sub.1 and R.sub.2 independently represent an aliphatic, alicyclic or aromatic group;

G represents an --OR.sub.5 group or an --NHR.sub.6 group, where R.sub.5 is hydrogen or a hydrolyzable moiety such as an acyl group and R.sub.6 is hydrogen, an alkyl group of 1 to 22 carbon atoms (e.g. methyl, ethyl, butyl, decyl, hexadecyl, etc.) or an --SO.sub.2 PUG moiety;

Z represents the atoms necessary to complete a one-, two- or three-ringed carbocyclic or heterocyclic group containing 5 to 7 nuclear atoms in each ring, the sulfonamido group being joined to a position on Z so as to be conjugated to G; and

PUG represents a photographically useful group.

Representative Z groups include benzene, naphthalene, anthracene, pyrazolone, pyridine, quinoline, pyrimidine, coumarin, indole, and the like.

Representative PUG groups include a dye, a dye precursor, or a photographic reagent such as a development inhibitor, a development accelerator, a bleach inhibitor, a bleach accelerator, a developing agent, a silver halide solvent, a silver complexing agent, a fixing agent, a toner, a hardener, a fogging agent, an antifoggant, a chemical or spectral sensitizer, a desensitizer and the like.

In accordance with a preferred embodiment of the present invention there is provided a photographic element comprising a support and at least one photosensitive silver halide emulsion layer having associated therewith a ballasted non-diffusible p-sulfonamidophenol or p-sulfonamidoaniline having attached through the sulfonamido group, a photographically useful group which is alkali-cleavable upon oxidation, the p-sulfonamidophenol or p-sulfonamidoaniline containing, meta to the sulfonamido group, an N,N-disubstituted carbamoyl ballast group. As used herein the terms phenol and aniline are generic to monocyclic and bicyclic compounds, and, hence, would encompass naphthols as well as phenols and naphthylamines as well as anilines.

Preferred p-sulfonamidophenols and p-sulfonamidoanilines of this invention can be represented by the structure: ##STR6## where:

X represents the atoms required to complete a benzene or naphthalene ring;

R.sub.1 and R.sub.2 independently represent an alicyclic, aliphatic or aromatic group;

G represents an --OR.sub.5 group or an --NHR.sub.6 group, where R.sub.5 is hydrogen or a hydrolyzable moiety such as an acyl group and R.sub.6 is hydrogen, an alkyl group of 1 to 22 carbon atoms (e.g. methyl, ethyl, butyl, decyl, hexadecyl, etc.) or an --SO.sub.2 PUG moiety; and

PUG is a photographically useful group.

In the above Formulae I, II and III, the substituents R.sub.1 and R.sub.2 in the N,N-disubstituted carbamoyl ballast group are of such size and configuration that the compound to which the ballast group is attached is rendered non-diffusible during development in an alkaline process composition. Preferably R.sub.1 and R.sub.2 together contain a total of eight or more carbon atoms, e.g., 8 to 50 carbon atoms.

Exemplary of suitable R.sub.1 and R.sub.2 groups are alicyclic groups such as cycloalkyl of 4 to 22 carbon atoms (e.g. cyclopropyl, cyclohexyl, cyclodecyl, cyclooctadecyl, etc.), aliphatic groups such as straight and branched chain alkyl groups of 1 to 22 carbon atoms including aralkyl groups and aryloxyalkyl groups (e.g. methyl, butyl, dodecyl, benzyl, phenoxypropyl, etc.) and aromatic groups such as aryl groups of 6 to 22 carbon atoms including alkaryl groups and alkoxyaryl groups (e.g. phenyl, naphthyl, methylphenyl, butoxyphenyl, etc.).

In a particularly preferred embodiment of this invention R.sub.1 and R.sub.2 are straight chain alkyl groups of 1 to 22 carbon atoms such as ethyl, pentyl, octyl, dodecyl, pentadecyl, octadecyl, 2,4-di-t-pentylphenoxybutyl, and the like and together R.sub.1 and R.sub.2 contain a total of eight or more carbon atoms. In a highly preferred embodiment R.sub.1 and R.sub.2 each represent the same straight chain alkyl group containing 10 to 22 carbon atoms, such as decyl, dodecyl, pentadecyl and octadecyl.

In a particularly preferred embodiment of this invention G is --OR.sub.5 and R.sub.5 is hydrogen.

In a particularly preferred embodiment of this invention PUG represents a dye or dye precursor moiety. Such moieties are well known to those skilled in the art and include dyes such as azo, azomethine, azopyrazolone, indoaniline, indophenol, anthraquinone, triarylmethane, alizarin, merocyanine, nitro, quinoline, cyanine, indigoide, phthalocyanine, metal complexed dyes, etc and dye precursors such as leuco dyes, shifted dyes, etc.

These dye and dye precursor moieties may contain solubilizing groups, if desired, to aid in transfer of the dye. Dye precursor moieties can be converted to dyes by means well known to those skilled in the art, e.g. hydrolysis or oxidation, either in the photosensitive element, in the processing composition or in the dye image-receiving layer to form a visible dye. Preferred dyes and dye precursors are described in U.S. Pat. No. 3,880,658 of Lestina et al., U.S. Pat. No. 3,931,144 of Eldredge et al., U.S. Pat. No. 3,932,380 of Krutak et al., U.S. Pat. No. 3,932,381 of Haase et al. and U.S. Pat. No. 3,942,987 of Landholm et al. As used hereinafter, unless the context indicates otherwise, the term "dye" includes dye precursors, it being understood that the dye precursor is converted to the desired dye to form the final image.

Particularly preferred p-sulfonamido phenols and anilines of this invention can be represented by the structure: ##STR7## where:

X represents the atoms to complete a benzene or naphthalene ring;

Dye is a dye or dye precursor moiety as defined above; and

R.sub.1 and R.sub.2 are each straight chain alkyl groups of 1 to 30 carbon atoms and together contain a total of 8 to 50 carbon atoms.

Preferred compounds within the scope of this invention include:

Photographic elements containing redox releasing compounds of the present invention can be used in a variety of processes in which an imagewise distribution of the photographically useful group is desired to aid in image formation or enhancement. The photographically useful group can be released in an imagewise manner from the redox releasing compound (and thereby provide an imagewise distribution of a photographically useful compound such as a photographic dye or dye precursor or a photographic reagent) by treating an imagewise exposed silver halide element containing a redox releasing compound with an alkaline processing composition (having a pH of e.g. 9-14) in the presence of a silver halide developing agent to effect development of the silver halide as a function of exposure. In developing silver halide, the developing agent is converted to its oxidized form, in which form it crossoxidizes (directly or indirectly) the redox releasing compound, which in its oxidized form cleaves thus releasing an imagewise distribution of the photographically useful compound. This imagewise distribution can be used in a variety of ways to form or enhance a photographic image.

The redox releasing compounds described herein have particular utility in diffusion transfer processes where it is desired to have a dye or dye precursor released imagewise. However, in certain embodiments this invention relates to the release of an imagewise distribution of a diffusible photographically useful compound which is a photographic reagent. Typical useful photographic reagents are known in the art, such as in U.S. Pat. Nos. 3,227,551, 3,698,898, 3,379,529 and 3,364,022, for example, a silver complexing agent, a silver halide solvent, a toner, a hardener, an antifoggant, a fogging agent, a chemical or spectral sensitizer, a desensitizer, a developer, a development inhibitor, a development-accelerator, a bleach inhibitor or a bleach accelerator. In other words, -NHSO.sub.2 PUG in the above formulae includes any moiety which, in combination with a hydrogen atom, provides a photographic reagent upon cleavage.

The use of dye redox releasing compounds to form photographic color images will be described in detail hereinafter as exemplary of the ways in which redox releasing compounds of this invention can be used.

Photographic color images can be prepared with elements of this invention by treating the element in the manner described above to form an imagewise distribution of diffusible dye or dye precursor as a function of the imagewise exposure of the silver halide emulsion. Images can be formed employing the imagewise released diffusible dye, or the remaining imagewise distribution of unreacting dye redox releaser, or both. The released diffusible dye or dye precursor can be allowed to diffuse to a receiver sheet or layer to form a transfer image. Alternatively, it can merely be removed from the element and not made further use of. Whether the imagewise pattern of diffusible dye is used to form an image or not, the remaining dye redox releaser can be used as a retained image in the layer in which it was initially coated. This could include removing residual silver and silver halide by any conventional procedure known to those skilled in the art, such as a bleach bath followed by a fix bath, a bleach-fix bath, etc. In the event that the photographically useful group in the redox dye releaser is a dye precursor rather than a dye, the process for forming a retained image would include the step of converting the dye precursor to the desired dye. Alternatively, once the initially formed diffusible dye is removed from the element, the residual dye redox releaser can be employed to form a transfer image by oxidizing the dye redox releaser (e.g. by cross oxidation, or otherwise) to yield a second distribution of diffusible dye which can be transferred to a suitable receiver sheet or layer.

A preferred process for producing a photographic transfer image in color using compounds of our invention comprises the steps of:

1. treating an imagewise exposed photosensitive element of the invention with an alkaline processing composition in the presence of a silver halide developing agent to effect development of the silver halide emulsion layers as a function of exposure, thereby oxidizing the developing agent and the oxidized developing agent in turn cross-oxidizing the dye redox releasing compound;

2. forming an imagewise distribution of diffusible released dye as a function of the development of the silver halide emulsion layers by cleaving, under alkaline conditions, cross-oxidized dye redox releasing compounds; and

3. diffusing out of the layer in which the dye redox releaser was coated at least a portion of the imagewise distributions of diffusible released dye.

The photosensitive element in the above-described process can be treated with an alkaline processing composition to effect or initiate development in any manner. A preferred method for applying processing compositions is by the use of a rupturable container or pod which contains the composition. In general, the processing composition contains the developing agent for development although the composition could just be an alkaline solution where the developer is incorporated in the photosensitive element, in which case the alkaline solution serves to activate the incorporated developer.

A preferred photographic film unit according to our invention comprises:

1. a photographic element as described above;

2. an alkaline processing composition; and

3. means for discharging the alkaline processing composition within the film unit (such as a rupturable container which is adapted to be positioned during processing of the film unit so that a compressive force applied to the container by the pressure-applying members will effect a discharge of the contents of the container within the film unit); the film unit containing a silver halide developing agent.

The film unit can include a dye image-receiving layer located on a separate support adapted to be superposed on the photographic element after exposure thereof. Such dye-image-receiving layers are generally disclosed, for example, in U.S. Pat. No. 3,362,819. When the means for discharging the processing composition is a rupturable container, typically it is positioned in relation to the photographic element and the image-receiving element so that a compressive force applied to the container by pressure-applying members, such as found in a camera designed for in-camera processing, will effect a discharge of the contents of the container between the dye-image-receiving layer and the outermost layer of the photographic element. After processing, the dye image-receiving element is separated from the photographic element.

The film unit can include a dye image-receiving layer located integral with the photographic element. One useful format for integral receiver photographic elements is disclosed in Canadian Pat. No. 928,560. In such an embodiment, the support for the photographic element is transparent and is coated with a dye-image-receiving layer, a substantially opaque light reflective layer, e.g. TiO.sub.2, and then the photosensitive layer or layers described above. After exposure of the photographic element, a rupturable container containing an alkaline processing composition and an opaque process sheet are brought into superposed position. Pressure-applying members in the camera rupture the container and spread processing composition over the photographic element as the film unit is withdrawn from the camera. The processing composition develops each exposed silver halide emulsion layer and dye images are formed as a function of development which diffuse to the dye-image-receiving layer to provide a positive, right-reading image which is viewed through the transparent support on the opaque reflecting layer background.

Another format for integral receiver photographic elements in which the present invention can be employed is disclosed in Canadian Pat. No. 928,559. In this embodiment, the support for the photographic element is transparent and is coated with the dye-image-receiving layer, a substantially opaque, light-reflective layer and the photosensitive layer or layers described above. A rupturable container containing an alkaline processing composition and an opacifier is positioned adjacent to the top layer and a transparent top sheet. The film unit is placed in a camera, exposed through the transparent top sheet and then passed through a pair of pressure-applying members in the camera as it is being removed therefrom. The pressure-applying members rupture the container and spread processing composition and opacifier over the photographic element to render the negative portion light insensitive. The processing composition develops each silver halide layer and the dye images, which are formed as a result of development, diffuse to the dye image-receiving layer to provide a right-reading image when viewed through the transparent support against the opaque reflecting layer background.

Still other useful integral formats in which the sulfonamido compounds can be employed are described in U.S. Pat. Nos. 3,415,644; 3,415,645; 3,415,646; 3,647,437; and 3,635,707.

The photographic elements of the present invention can be used to produce positive images in single or multicolors. In a three-color system, the silver halide emulsion layers of the photographic element will have associated therewith a dye-image-providing material, at least one of which is a dye redox releasing compound of this invention, each dye-image-providing material possessing a predominant spectral absorption within the region of the visible spectrum to which said silver halide emulsion is sensitive, i.e., the blue-sensitive silver halide emulsion layer will have a yellow dye-image-providing material associated therewith, the green-sensitive silver halide emulsion layer will have a magenta dye-image-providing material associated therewith, and the red-sensitive silver halide emulsion layer will have a cyan dye-image-providing material associated therewith. Those silver halide emulsion layers that do not have associated therewith a dye redox releasing compound of this invention can have associated therewith another dye redox releasing compound or another dye-image-providing material. The dye redox releasing compound associated with the silver halide emulsion layer can be contained either in the silver halide emulsion layer itself or in a layer contiguous to the silver halide emulsion layer.

The concentration of the dye redox releasing compounds that are employed in the present invention can be varied over a wide range depending upon the particular compound employed and the results which are desired. For example, the dye redox releasing compounds of the present invention can be coated in layers as dispersions in a hydrophilic film-forming natural or synthetic polymer, such as gelatin, polyvinyl alcohol, etc., which is adapted to be permeated by aqueous alkaline processing composition. Preferably, the ratio of dye redox releasing compound to polymer will be about 0.25 to about 4.0. The compounds can then be incorporated in a gelatin by techniques known in the art (e.g., use of a high boiling water immiscible organic solvent or a low boiling or water miscible organic solvent). Any silver halide developing agent can be used as long as it cross oxidizes with the image dye providing compounds used herein. The developer can be employed in the photosensitve element to be activated by the alkaline processing composition. Suitable developers can be selected from hydroquinone, aminophenols, e.g., N-methylaminophenol, Phenidone (1-phenyl-3-pyrazolidone) trademark of Ilford, Ltd; Dimezone (1-phenyl-4,4-dimethyl-3-pyrazolidone) trademark of Eastman Kodak Company; 1-phenyl4-methyl-4-hydroxymethyl-3-pyrazolidone, N,N-diethyl-pphenylenediamine, 3-methyl-N,N-diethyl-p-phenylenediamine, 3-methoxy-N,N-diethyl-p-phenylenediamine, N,N,N',N'-tetramethyl-p-phenylenediamine, etc. The black-and-white developers in this list are preferred, in that they have a reduced propensity to stain the dye image-receiving layer.

In a preferred embodiment of our invention, the silver halide developer in our process becomes oxidized upon development and reduces silver halide to silver metal. The oxidized developer then cross-oxidizes the redox dye releasing compound. The product of cross-oxidation then undergoes alkaline hydrolysis, thus releasing an imagewise distribution of diffusible dye or dye precursor which then diffuses to the receiving layer to provide the dye image. The diffusible moiety is transferable in alkaline processing composition either by virture of its self-diffusivity or by having attached to it one or more solubilizing groups.

In using dye redox releasing compounds according to our invention, the production of diffusible dye images is a function of development of the silver halide emulsions with a silver halide developing agent to form either negative or direct positive silver images in the emulsion layers. If the silver halide emulsion employed forms a direct positive silver image, such as a direct positive internal-image emulsion or a solarizing emulsion, which develops in unexposed areas, a positive image can be obtained in the dye image-receiving layer. After exposure of the film unit, the alkaline processing composition permeates the various layers to initiate development in the unexposed photosensitive silver halide emulsion layers. The development agent present in the film unit develops each of the silver halide emulsion layers in the unexposed areas (since the silver halide emulsions are direct-positive ones), thus causing the developing agent to become oxidized imagewise corresponding to the unexposed areas of the direct-positive silver halide emulsion layers. The oxidized developing agent then cross-oxidizes the dye redox releasing compounds and the oxidized form of the compounds then undergoes a base-catalyzed reaction, in a preferred embodiment of our invention, to release the preformed dyes imagewise as a function of the imagewise exposure of each of the silver halide emulsion layers. At least a portion of the imagewise distributions of diffusible dyes diffuse to the image-receiving layer to form a positive image of the original subject. After being contacted by the alkaline processing composition, a pH-lowering layer in the film unit lowers the pH of the film unit (or the image-receiving unit) to terminate development and stabilize the image.

Useful internal-image silver halide emulsions are direct positive emulsions that form latent images predominantly inside the silver halide grains, as distinguished from silver halide grains that form latent images predominantly on the surface thereof. Such internal image emulsions are described by Davey et al in U.S. Pat. No. 2,592,250, by Evans in U.S. Pat. No. 3,761,276, dated Sept. 25, 1973 and by Klotzer et al in U.S. Pat. Nos. 3,935,014 and 3,957,488. Internal-image silver halide emulsions can be defined in terms of the increased maximum density obtained when developed with "internal-type" developers over that obtained when developed with "surface-type" developers. Suitable internal-image emulsions are those which, when measured according to normal photographic techniques by coating a test portion of the silver halide emulsion on a transparent support, exposing to a light intensity scale having a fixed time between 0.01 and 1 second, and developing for 3 minutes at 20.degree. C. in Developer A below ("internal-type" developer), have a maximum density at least five times the maximum density obtained when an equally exposed silver halide emulsion is developed for 4 minutes at 20.degree. C. in Developer B described below ("surface-type" developer). Preferably, the maximum density in Developer A is at least 0.5 density unit greater than the maximum density in Developer B.

The internal-image silver halide emulsions when processed in the presence of fogging or nucleating agents provide direct positive silver images. Such emulsions are particularly useful in the above-described embodiment. Suitable fogging agents include the hydrazines disclosed in Ives U.S. Pat. Nos. 2,588,982 issued Mar. 11, 1952, and 2,563,785 issued Aug. 7, 1951; the hydrazides and hydrazones disclosed in Whitmore U.S. Pat. No. 3,227,552 issued Jan. 4, 1966; hydrazone quaternary salts described in Lincoln and Heseltine U.S. Pat. No. 3,615,615 issued Oct. 16, 1971; hydrazone containing polymethine dyes described in Spence and Janssen U.S. Pat. No. 3,718,470 issued Feb. 27, 1973; hydrazide-containing thioureas and thiones described in Leone et al U.S. Pat. 4,030,925 and U.S. Application Ser. No. 700,981 filed June 29, 1976, now U.S. Pat. No. 4,080,207; or mixtures thereof. The quantity of fogging agent employed can be widely varied depending upon the results desired. Generally, the concentration of fogging agent is from about 0.4 to about 8 grams per mole of silver in the photosensitive layer in the photosensitive element or from about 0.1 to about 2 grams per liter of developer if it is located in the developer. The fogging agents described in U.S. Pat. Nos. 3,615,615, 3,718,470, 4,030,925 and Ser. No. 700,981, however, are preferably used in concentrations of about 2 to 400 milligrams per mole of silver in the photosensitive layer.

The solarizing direct-positive silver halide emulsions useful in the above-described embodiment are well-known silver halide emulsions which have been effectively fogged either chemically, such as by the use of reducing agents, or by radiation to a point which corresponds approximately to the maximum density of the reversal curve as shown by Mees, The Theory of the Photographic Process, published by the Macmillan Co., New York, New York, 1942, pages 261-297. Typical methods for the preparation of solarizing emulsions are shown by Groves British Pat. No. 413,245, Feb. 25, 1936, who subjected emulsions to Roentgen rays "until an emulsion layer formed therefrom, when developed without preliminary exposure, is blackened up to the apex of its graduation curve"; Szaz British Pat. No. 462,730, Mar. 15, 1937, the use of either light or chemicals such as silver nitrate, to convert ordinary silver halide emulsions to solarizing direct positive emulsions; and Arens U.S. Pat. No. 2,005,837, June 25, 1935, the use of silver nitrate and other compounds in conjunction with heat to effect solarization. Particularly useful are the fogged direct-positive emulsions of Berriman U.S. Pat. No. 3,367,778; Illingsworth U.S. Pat. Nos. 3,501,305, 3,501,306, 3,501,307; and combinations thereof.

Other embodiments in which our redox dye-releasing compounds can be employed include the materials and techniques described in U.S. Pat. Nos. 3,227,550, 3,227,551, 3,227,552 and 3,364,022.

Negative silver halide emulsions useful in certain embodiments of this invention can comprise, for example, silver chloride, silver bromide, silver chlorobromide, silver bromoiodide, silver chlorobromoiodide or mixtures thereof. The emulsions can be coarse- or fine-grain and can be prepared by any of the well-known procedures, e.g. single-jet emulsions such as those described in Trivelli and Smith, The Photographic Journal, Vol. LXXIX, May 1939 (pp. 330-338), double-jet emulsions, such as Lippmann emulsions, ammoniacal emulsions, thiocyanate or thioether ripened emulsions such as those described in Nietz et al U.S. Pat. No. 2,222,264 issued Nov. 19, 1940; Illingsworth U.S. Pat. No. 3,320,069 issued May 16, 1967; and Jones U.S. Pat. No. 3,574,628 issued Apr. 13, 1971. The emulsions may be monodispersed regular-grain emulsions such as the type described in Klein and Moisar, Journal Photographic Science, Vol. 12, No. 5, September-October, 1964 (pp. 242-251).

Another embodiment of our invention uses the image-reversing technique disclosed in British Pat. No. 904,364, page 19, lines 1-41. In this system our redox dye-releasing compounds are used in combination with physical development nuclei in a nuclei layer contiguous to the photosensitive silver halide negative emulsion layer. The film unit contains a silver halide solvent, preferably in a rupturable container with the alkaline processing composition.

The various silver halide emulsion layers of a color film assembly of the invention can be disposed in the usual order, i.e., the blue-sensitive silver halide emulsion layer first with respect to the exposure side, followed by the green-sensitive and red-sensitive silver halide emulsion layers. If desired, a yellow dye layer or a yellow colloidal silver layer can be present between the blue-sensitive and green-sensitive silver halide emulsion layer for absorbing or filtering blue radiation that may be trasmitted through the blue-sensitive layer. If desired, the selectivity sensitized silver halide emulsion layers can be disposed in a different order, e.g. the blue-sensitive layer first with respect to the exposure side, followed by the red-sensitive and green-sensitive layers.

The rupturable container employed in this invention can be of the type disclosed in U.S. Pat. Nos. 2,543,181; 2,643,886; 2,653,732; 3,724,051; 3,056,492; 3,056,491 and 3,152,515. In general, such containers comprise a rectangular sheet of fluid and air impervious material folded longitudinally upon itself to form two walls which are sealed to one another along their longitudinal and end margins to form a cavity in which processing solution is contained.

In a color film unit according to this invention, each silver halide emulsion layer containing a redox dye releasing compound or having a redox dye releasing compound present in a contiguous layer may be separated from the other silver halide emulsion layers in the image-forming portion of the film unit by materials such as gelatin, calcium alginate, those disclosed in U.S. Pat. No. 3,384,483, polymeric materials such as polyvinylamides as disclosed in U.S. Pat. No. 3,421,892, and those described in French Pat. No. 2,028,236 or U.S. Pat. Nos. 2,992,104; 3,043,692; 3,044,873; 3,061,873; 3,061,428; 3,069,263; 3,069,264; 3,121,011; 3,427,158; and in Research Disclosure, Item No. 15162 (November 1976). Research Disclosure is published by Industrial Opportunities Ltd., Homewell Havant, Hampshire, PO9 1EF, U.K.

Generally speaking, except where noted otherwise, the silver halide emulsion layers in the invention comprise photosensitive silver halide dispersed in gelatin and are about 0.3 to 3 microns in thickness; the dye image-providing materials are dispersed in an aqueous alkaline solution-permeable polymeric binder, such as gelatin, as a separate layer about 0.3 to 3 microns in thickness; and the alkaline solution-permeable polymeric interlayers, e.g., gelatin, are about 0.5 to 5 microns in thickness. Of course, these thicknesses are approximate only and can be modified according to the product desired.

Any material can be employed as the image-receiving layer in this invention as long as the desired function of mordanting or otherwise fixing the dye images will be obtained. The particular material chosen will, of course, depend upon the dye to be mordanted. If acid dyes are to be mordanted, the image-receiving layer can contain basic polymeric mordants such as polymers of amino guanidine, derivatives of vinyl methyl ketone such as described in Minsk U.S. Pat. No. 2,882,156, issued Apr. 14, 1959, and basic polymeric mordants such as described in Cohen et al U.S. Pat. No. 3,625,694, issued Dec. 7, 1971; U.S. Pat. No. 3,709,690, issued Jan. 9, 1973; and U.S. Pat. No. 3,898,088 issued Aug. 5, 1975; U.S. Pat. No. 3,859,096, issued Jan. 1, 1975; and Research Disclosure, Item No. 15162 (November 1976). Research Disclosure is published by Industrial Opportunities Ltd., Homewell Havant, Hampshire, PO9 1EF, U.K.

Preferred mordants are cationic mordants such as polymeric compounds composed of a polymer having quaternary nitrogen groups and at least two aromatic nuclei for each quaternary nitrogen in the polymer cation (i.e., having at least two aromatic nuclei for each positively charged nitrogen atom), such polymeric compounds being substantially free of carboxy groups. These preferred polymeric cationic mordants are described further in the above-mentioned U.S. Pat. No. 3,709,690, U.S. Pat. No. 3,898,088, and U.S. Pat. No. 3,958,995.

Other mordants useful in our invention include poly-4-vinylpyridine, the 2-vinyl pyridine polymer methyl p-toluenesulfonate and similar compounds described in Sprague et al U.S. Pat. No. 2,484,430, issued Oct. 11, 1949, and octyl trimethylammonium bromide, etc. Effective mordanting compositions are also described in Whitmore U.S. Pat. No. 3,271,148 and Bush U.S. Pat. No. 3,271,147, both issued Sept. 6, 1966.

Generally, good results are obtained when the image-receiving layer, preferably alkaline solution-permeable, is transparent and about 0.25 to about 0.40 mil in thickness. This thickness, of course, can be modified depending upon the result desired. The image-receiving layer can also contain ultraviolet absorbing materials to protect the mordanted dye images from fading due to ultraviolet light, brightening agents such as the stilbenes, coumarins, triazines, oxazoles, dye stabilizers such as the chromanols, alkylphenols, etc.

Use of pH-lowering material in the dye image-receiving element of a film unit according to the invention will usually increase the stability of the transferred image. Generally, the pH-lowering material will effect a reduction in the pH of the image layer from about 13 or 14 to at least 11 and preferably 4-8 within a short time after imbibition. For example, polymeric acids as disclosed in U.S. Pat. No. 3,362,819, or solid acids or metallic salts, e.g. zinc acetate, zinc sulfate, magnesium acetate, etc., as disclosed in U.S. Pat. No. 2,584,030 may be employed with good results. Such pH-lowering materials reduce the pH of the film unit after development to terminate development and substantially reduce further dye transfer and thus stabilize the dye image.

An inert timing or spacer layer can be employed in the practice of our invention over the pH-lowering layer which "times" or controls the pH reduction as a function of the rate at which alkali diffuses through the inert spacer layer. The timing layer may be effective in evening out the various reaction rates over a wide range of temperatures, e.g., premature pH reduction is prevented when imbibition is effected at temperatures above room temperature, for example, at 95.degree.-100.degree. F. The timing layer is usually about 0.1 to about 0.7 mil in thickness. Especially good results are obtained when the timing layer comprises a hydrolyzable polymer or a mixture of such polymers which are slowly hydrolyzed by the processing composition. Examples of such hydrolyzable polymers include polyvinyl acetate, polyamides, cellulose esters (e.g. cellulose acetate), maleic anhydride-styrene copolymers, and mixtures of such hydrolyzable polymers. Suitable timing layers are described in U.S. Pat. No. 4,009,030 and U.S. application Ser. Nos. 676,945 and 676,947, both filed Apr. 14, 1976 and now U.S. Pat. Nos. 4,056,394 and 4,061,496 respectively.

The alkaline processing composition employed in this invention is the conventional aqueous solution of an alkaline material, e.g., sodium hydroxide, sodium carbonate or an amine such as diethylamine, preferably possessing a pH in excess of 11, and preferably containing a developing agent as described previously. The solution also preferably contains a viscosity-increasing compound such as a high-molecular-weight polymer, e.g. a water-soluble ether inert to alkaline solutions such as hydroxyethyl cellulose or alkali metal salts of carboxymethylcellulose such as sodium carboxymethyl cellulose. A concentration of viscosity-increasing compound of about 1 to about 5 percent by weight of the processing composition is preferred which will impart thereto a viscosity of about 100 cp. to about 200,000 cp. In certain embodiments of our invention, an opacifying agent, e.g., TiO.sub.2, carbon black, pH indicator dyes, etc. may be added to the processing composition.

While the alkaline processing composition used in this invention can be employed in a rupturable container, as described previously, to conveniently facilitate the introduction of processing composition into the film unit, other methods of inserting processing composition into the film unit could also be employed, e.g., interjecting processing solution with communicating members similar to hypodermic syringes which are attached either to a camera or camera cartridge.

The alkaline solution-permeable, substantially opaque, light-reflective layer employed in certain embodiments of photographic film units of our invention can generally comprise any opacifier dispersed in a binder as long as it has the desired properties. Particularly desirable are white light-reflective layers since they would be esthetically pleasing backgrounds on which to view a transferred dye image and would also possess the optical properties desired for reflection of incident radiation. Suitable opacifying agents include titanium dioxide, barium sulfate, zinc oxide, barium stearate, silver flake, silicates, alumina, zirconium oxide, zirconium acetyl acetate, sodium zirconium sulfate, kaolin, mica, or mixtures thereof in widely varying amounts depending upon the degree of opacity desired. The opacifying agents may be dispersed in any binder such as an alkaline solution-permeable polymeric matrix such as, for example, gelatin, polyvinyl alcohol, and the like. Brightening agents such as the stilbenes, coumarins, triazines and oxazoles can also be added to the light reflective layer, if desired. When it is desired to increase the opacifying capacity of the light-reflective layer, dark-colored opacifying agents, e.g., carbon black, nigrosine dyes, etc., may be added to it, or coated in a separate layer adjacent to the light-reflective layer.

The supports for the photographic elements of this invention can be any material as long as it does not deleteriously effect the photographic properties of the film unit and is dimensionally stable. Typical flexible sheet materials include cellulose nitrate film, cellulose acetate film, poly(vinyl acetal) film, polystyrene film, poly(ethyleneterephthalate) film, polycarbonate film, poly-.alpha.-olefins such as polyethylene and polypropylene film, and related films or resinous materials. The support can be from about 2 to about 9 mils in thickness.

The silver halide emulsions useful in our invention are well known to those skilled in the art and are described in Product Licensing Index, (Research Disclosure), Vol. 92, December, 1971, publication 9232, p. 107, paragraph I, "Emulsion types"; they may be chemically and spectrally sensitized as described on page 107, paragraph III, "Chemical sensitization," and pp. 108-109, paragraph XV, "Spectral sensitization," of the above article; they can be protected against the production of fog and can be stabilized against loss of sensitivity during keeping by employing materials described on p. 107, paragraph V, "Antifoggants and stabilizers," of the above article; they can contain development modifiers, hardeners and coating aids as described on pp. 107-108, paragraph IV, "Development modifiers"; paragraph VII, "Hardeners"; and paragraph XII, "Coating aids", of the above article; they and other layers in the photographic elements used in this invention can contain plasticizers, vehicles and filter dyes described on p. 108, paragraph XI, "Plasticizers and lubricants," and paragraph VIII, "Vehicles", and p. 109, paragraph XVI, "Absorbing and filter dyes," of the above article; they and other layers in the photographic elements used in this invention may contain addenda which are incorporated by using the procedures described on p. 109, paragraph XVII, "Methods of addition," of the above article; and they can be coated by using the various techniques described on p. 109, paragraph XVIII, "Coating procedures," of the above article, the disclosures of which are hereby incorporated by reference.

The following examples are provided for a further understanding of the invention. ##STR32##

To 26.5 g of the ester a were added 35.3 g of di-n-dodecylamine. The mixture was heated at about 120.degree. C. for 15 minutes. The temperature of the oil bath was then increased to 180.degree.-190.degree. C. and the phenol sideproduct was removed under a vacuum aspirator. The amber-colored oil was then added while hot to 400 ml of n-hexane. No precipitation appeared on cooling and standing. The solvent was removed in vacuo to yield an oil which gave a yellow precipitate on cooling in a dry ice--acetone bath. Crystallization from ethyl alcohol gave light-yellow crystals. A second crystallization from ethyl alcohol gave practically colorless crystals, m.p. 30.degree.-32.degree. C. ##STR33##

To 15.0 g of the naphthol b dissolved in methanol, sodium hydroxide and tetrahydrofuran, was added, at 0.degree. C., a diazonium salt solution prepared from 3.7 g of p-anisidine, 30 ml of water, 9.0 ml concentrated hydrochloric acid and 2.1 g of sodium nitrite dissolved in 30 ml water. The mixture was stirred for 30 minutes at 5.degree. C. A solution of 25 ml of glacial acetic acid in 300 ml of ice water was then added while stirring vigorously. The bright orange precipitate turned a light brown. The product was collected and was washed thoroughly with water. ##STR34##

To 9.2 g of the azonaphthol c dissolved in 200 ml of hot ethanol was added a solution of 6.0 g of sodium dithionite in 50 ml of water. The reaction mixture was stirred vigorously while heating to reflux. After 1/2 hour the dark solution had become yellow in color and an oil was visible on top of the solution. The reaction mixture was stirred and heated for 1/2 hour followed by cooling in an ice bath with vigorous stirring. At about 5.degree. C. the light oil solidified. The off-white product was then collected and washed thoroughly with water. Crystallization from n-hexane gave off-white crystals; m.p. 55.degree.-56.degree. C. ##STR35##

To 4.0 g of the aminonaphthol d dissolved in 50 ml of dry pyridine were added 2.8 g of the sulfonyl chloride e at 12.degree. C. under nitrogen (temperature rose to about 15.degree. C.). The reaction mixture was stirred at 15.degree. C. for 2 hours and at room temperature overnight. The reaction mixture was then added to a mixture of 50 ml of concentrated hydrochloric acid and about 50 ml of ice water while stirring vigorously. The product was collected and washed thoroughly with water. Crystallization from acetonitrile (twice) gave 2.5 g of yellow-orange crystals; m.p. 91.degree.-93.degree. C. ##STR36##

To 3.0 g of the aminoaphthol d (prepared according to Steps 1 through 3 of Example 1) dissolved in 50 ml of dry pyridine were added 2.6 g of the sulfonyl chloride f at 15.degree. C. under nitrogen. The reaction mixture was stirred at 15.degree. C. for 2 hours and at room temperature overnight. The reaction mixture was then added to a mixture of 50 ml of concentrated hydrochloric acid and 50 ml water with vigorous stirring. The magenta product was collected and washed thoroughly with water. Crystallization from ethyl acetate gave 2.1 g of product; m.p. 185.degree.-188.degree. C.

Color photographic elements identified by the following schematic structure were prepared. The quantities of components are stated as grams/meter.sup.2 in parenthesis. Silver halide quantities are given in terms of silver.

Separate elements contained a cyan, magenta or yellow dye redox releaser of the invention, as compared to control elements containing dye redox releasers of the prior art having the same cyan, magenta and yellow dye moieties. The incorporated dye redox releaser and its quantity in each element was as follows: ##STR37##

Samples of each element were exposed through a graduated density test object and processed by immersing the sample in a developer solution consisting of:

Elements A and B were developed for 8 minutes at 24.degree. C., elements C and D for 6 minutes at 24.degree. C., and elements E and F for 3 minutes at 24.degree. C. All samples were then washed for 1 minute, bleach-fixed for 2 minutes, washed for 2 minutes and immersed in a pH 7.0 buffer solution for 1 minute. There was obtained a graduated density dye image.

The results were evaluated by generating from the dye images the density vs. exposure curves shown in FIGS. 1, 2 and 3.

It is observed that the cyan, magenta and yellow dye images produced with the dye redox releasers of this invention demonstrate a substantial increase in photographic speed and significant reduction in minimum densities. Furthermore, to evaluate yellow stain, the density to blue light in the D.sub.min areas of the dye images exhibited in FIGS. 1 and 2 were measured and showed 0.16 vs. 0.09 for Element A vs. B, and 0.21 vs. 0.12 for element C vs. D.

To compare the results at various processing pH's of dye-releasing-redox compounds of this invention relative to similar compounds of the prior art, two color photographic elements, similar to Elements C and D of Example 3, were prepared according to the following schematic structures:

Samples of each element were exposed through a graduated-density test object and processed by immersing separate samples in portions of a developer solution differing only in pH for 11/2 and 6 minutes at 38.degree. C. The process was as follows:

The sensitometric results were measured by plotting the dye images as density vs. exposure curves and are tabulated in Table I.

The data in Table I illustrates the following improvements with this invention: (1) lower green D.sub.min for the element of this invention compared with the control element. This demonstrates a more effective release of dye per unit of developed silver for the inventive element. (2) lower blue D.sub.min for the element of this invention compared with the control element. This presumably is due to less yellow strain from the residual ballasted carrier moiety of the invention as well as less residual dye. (3) Improved image discrimination for the inventive element, particularly under relatively low pH processing conditions is indicated by the larger difference between green D.sub.min and green D.sub.max for elements of this invention compared with the control element. (4) More rapid development. This is suggested by the release of dye from unexposed areas at elevated ph conditions; which indicates that the development times employed in this example were too long for the inventive element.

A control element was prepared containing prior art sulfonamidonaphthol dye redox releasers. The element was prepared by coating the following suitably hardened layers in the order given on a transparent poly(ethylene terephthalate) film support. The quantities of components are stated as grams/meter.sup.2 in parenthesis. Silver halide quantities are given in terms of silver.

Element I (control)

(1) image-receiving layer of a poly[styrene-co-N-benzyl-N,N-dimethyl-N-vinylbenzylammoniumsulfate-co-divi nylbenzene) latex mordant (2.16) and gelatin (2.16);

(2) reflecting layer of titanium dioxide (21.60) and gelatin (3.24);

(3) opaque layer of carbon black (290) and gelatin (1.73);

(4) cyan-dye-providing compound A (0.59) dissolved in diethyl lauramide (0.30) and dispersed in gelatin (1.08);

(5) red-sensitive, direct-positive silver bromide emulsion (1.35), gelatin (1.35), 5-sec-octadecylhydroquinone-2-sulfonic acid (16 g/mole silver), 1-[4-(2-formylhydrazino)-phenyl]-3-phenylthiourea (3.5 mg/mole silver), 1-acetyl-2-{p-[5-amino-2-(2,4-di-t-pentylphenoxy)benzamido]phenyl} hydrazine (85 mg/mole silver); (6) interlayer of gelatin (1.62) and 2,5-di-sec-dodecylhydroquinone (1.30);

(7) magenta-dye-providing compound B (0.54) dissolved in diethyllauramide (0.27) and dispersed in gelatin (1.22);

(8) green-sensitive, direct-positive silver bromide emulsion (1.35), gelatin (1.35), 5-sec-octadecylhydroquinone-2-sulfonic acid (16 g/mole silver), 1-[4-(2-formylhydrazino)phenyl]-3-phenylthiourea (2.5 mg/mole silver), 1-acetyl-2-{p-[5-amino-2-(2,4-di-t-pentyl phenoxy)-benzamido]phenyl}hydrazine (70 mg/mole silver);

(9) interlayer of gelatin (1.62) and 2,5-di-sec-dodecylhydroquinone (1.30);

(10) yellow-dye-providing compound C (0.65) dissolved in diethyllauramide (0.32) and dispersed in gelatin (1.46);

(11) blue-sensitive, direct-positive silver bromide emulsion (1.24), gelatin (1.24), 5-sec-octadecylhydroquinone-2-sulfonic acid (16 g/mole silver), 1-[4-(2-formylhydrazino)phenyl]-3-phenylthiourea (3.3 mg/mole silver), 1-acetyl-2-{p-[5-amino-2-(2,4-di-t-pentyl phenoxy)benzamido]-phenyl} hydrazine (80 mg/mole silver);

(12) overcoat layer of gelatin (0.89). ##STR38##

A second photographic element was prepared as above except that the cyan, magenta and yellow dye redox releasing compounds were replaced with lesser amounts of dye redox releasing compounds according to this invention, which contained the same release dyes as the control. Other variations included the use of less silver halide emulsion and gelatin and increased amounts of nucleating agents. The element is described as follows:

(1-3) same as the control;

(4) cyan dye redox compound IV (0.32) dissolved in diethyllauramide (0.16) and dispersed in gelatin (1.08);

(5) red-sensitive, direct-positive silver bromide emulsion (0.92), gelatin (0.92) and other components similar to the control;

(6) interlayer same as the control;

(7) magenta dye redox releasing compound XII (0.32) dissolved in diethyllauramide (0.16) and dispersed in gelatin (1.22);

(8) green-sensitive, direct-positive silver bromide emulsion (0.92), gelatin (0.92) and other components similar to the control;

(9) interlayer same as the control;

(10) yellow dye redox releasing compound XXIX (0.43), dissolved in diethyllauramide (0.22) and dispersed in gelatin (1.46);

(11) blue-sensitive, direct-positive silver bromide emulsion (0.92), gelatin (0.92) and other components similar to the control;

(12) overcoat layer same as the control.

Samples of the above-prepared photosensitive elements were exposed through a multicolor graduated density test object. The exposed samples were then processed at 72.degree. F. (22.degree. C.) by rupturing a pod containing a viscous processing composition between the photosensitive element and a transparent cover sheet.

The processing composition was as follows:

The cover sheet consisted of a transparent poly(ethylene terephthalate) film support having coated thereon:

(1) a polyacrylic acid layer (189 meq/m.sup.2)

(2) a timing layer comprising 2.16 g/m.sup.2 of a mixture of 89% cellulose acetate (40% acetyl) and 11% poly(styrene-co-maleic anhydride) (approximately 50% hydrolyzed)

(3) a second timing layer comprising 2.16 g/m.sup.2 of a latex dispersion of poly(acrylonitrile co-vinylidene chloride-co-acrylic acid.

Multicolor transferred images were produced in the receiving layer as viewed through the transparent support. The resulting images were evaluated by generating the characteristic curves (density vs. exposure) shown in FIGS. 4 and 5.

It is observed from FIGS. 4 and 5 that substantially equal dye densities were produced with both elements, although significantly less material, e.g. silver halide, gelatin, and dye redox releasing compounds, were employed in the element of this invention. Additionally, a significant increase in speed, particularly in the green sensitive layer, was observed in the element according to this invention.

This 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.