US3687660A - Diffusion transfer photographic elements comprising 5-hydroxy-4-azabenzimidazole and a second azabenzimidazole,and processes for their use - Google Patents

Diffusion transfer photographic elements comprising 5-hydroxy-4-azabenzimidazole and a second azabenzimidazole,and processes for their use Download PDF

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US3687660A
US3687660A US81025A US3687660DA US3687660A US 3687660 A US3687660 A US 3687660A US 81025 A US81025 A US 81025A US 3687660D A US3687660D A US 3687660DA US 3687660 A US3687660 A US 3687660A
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image
layer
dye
azabenzimidazole
transfer
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James D Gondolfe
Ruth Seanlan
Jeanne A Ward
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Polaroid Corp
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Polaroid Corp
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C8/00—Diffusion transfer processes or agents therefor; Photosensitive materials for such processes
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
    • G03C1/34—Fog-inhibitors; Stabilisers; Agents inhibiting latent image regression

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  • the present invention relates to photography and more particularly to photographic products and processes.
  • photosensitive silver halide emulsions and particularly photosensitive gelatino-silver halide emulsions, have a tendency to lose sensitivity and to become spontaneously developable without exposure to light.
  • This phenomenon characterized as chemical fog, may be defined as the density above base level that is developed in emulsion areas that have received no intentional exposure and, in general, is not uniformly distributed over a selectively photoexposed emulsion, being greatest in the unexposed areas and decreasing with increased exposure in a non-linear manner.
  • Chemical fog may be divided into two classes: inherent fog, that is, fog which is emulsion initiated; and induced fog, that is, fog which is initiated during development. Induced fog appears to be due to physical development about extra-granular centers and inherent fog is probably due to the presence of grains bearing a catalytic site sensitivity speck which is unavoidably introduced and which is equivalent in its properties to latent image. Induced fog accordingly may be unaffected by the level of inherent fog.
  • an emulsion susceptible to the development of chemical fog requires silver halide grains possesing a catalytic center of sufficient size to be spontaneously developable and/or grains unprotected from non-discriminatory development.
  • This invention relates primarily to the latter item above, and more particularly to the use of a specified combination of synthetic, organic antifoggants.
  • Another object of the present invention is to provide novel processes and products, particularly adapted for obtaining monochromatic and multichromatic images by diffusion transfer, which exhibit decreased fog formation throughout an extended temperature range, and at the same time, exhibit an extended exposure latitude.
  • a still further object of the present invention is to provide novel photographic elements comprising not less than one silver halide emulsion having associated therewith specified transfer image-forming components which exhibit increased effective exposure latitude.
  • the invention accordingly comprises the process involving the several steps and the relation and order of one or more of such steps with respect to each of the others and the product possessing the features, properties and the relation of the elements which are exemplified in the following detailed disclosure and the scope of the application of which will be indicated in the claims.
  • FIG. 1 is a diagrammatic enlarged cross-sectional view of one embodiment of a film unit for obtaining multicolor images by a diffusion transfer photographic process illustrating the association of elements during one stage of the performance of a diffusion transfer process the thickness of the various materials being exaggerated;
  • FIG. 2 is a graph showing the characteristic curves of dye transfer images determined by plotting the reflection density of the transfer image, the red component thereof being taken as representative, as a function of the log exposure of the photoresponsive silver halide emulsion, wherein Curve A (solid line) represents the charactertistic curve of the red component of the transfer image prepared in accordance with the present invention and employing the novel combination of antifoggant materials as described herein, and Curve B (broken line) represents the charactertistic curve of the red component of the transfer image prepared in accordance with heretofore known techniques and employing an antifoggant component known to the prior art, said curves being set forth for the purpose of providing comparative data.
  • Curve A solid line
  • Curve B broken line
  • an exposed photographic emulsion is developed and, substantially concurrently therewith, an imagewise distribution of transfer image-forming components is provided as a function of the point-to-point degree of development. At least part of that imagewise distribution is transferred by diffusion to a contiguous image-receiving layer to provide the desired transfer image formation to that layer.
  • an exposed silver halide emulsion is developed and, substantially concurrently therewith, an imagewise distribution of soluble silver complex is obtained by reaction of a silver solvent with silver halide of the emulsion as a function of its point-to-point degree of exposure.
  • the photosensitive silver halide emulsion is developed with a viscous processing composition which is spread between an element comprising the silver halide emulsion and a print receiving element comprising a suitable silver precipitating layer.
  • the processing composition affects development of the emulsion and substantially contemporaneously therewith forms a soluble silver complex, for example, a thiosulfate or thiocyanate, as a function of the point-to-point degree of emulsion exposure.
  • a soluble silver complex for example, a thiosulfate or thiocyanate
  • This soluble silver complex is, at least in part, transported in the direction of the print receiving element and the silver thereof is largely precipitated in the silver precipitating layer of said element to form a transfer image therein.
  • U.S. Pat. No. 3,019,124 discloses the manufacture of photographic color screen elements particularly adapted for employment in multicolor dilfusion transfer processes; and U.S. Pats. Nos. 2,968,554 and 2,983,606 disclose diffusion transfer processes wherein a color screen element is utilized to provide a multicolor transfer image to a superposed imagereceiving layer.
  • U.S. Pats Nos. 2,774,608; 2,983,606; 3,087,817; and 3,345,163 discloses diffusion transfer processes wherein complete dyes are utilized to provide a color transfer image to a superposed image-receiving layer.
  • a photosensitive element containing a dye developer and a silver halide emulsion is exposed and wetted by a liquid processing composition, for example, by emersion, coating, spraying, flowing, etc., in the dark, and the exposed photosensitive element is superposed prior to, during or after wetting on a sheet-like support element which may be utilized as an image-receiving element.
  • the liquid processing composition is applied to the photosensitive element in a substantially uniform layer as the photosensitive element is brought into superposed relationship with the image-receiving layer.
  • the liquid processing composition permeates the emulsion to initiate development.
  • the dye developer is immobilized or precipitated in, for example, exposed areas as a function of the development.
  • Such immobilization is apparently, at least in part, due to a change in the solubility characteristics of the dye developer upon oxidation; particularly with regard to its solubility in alkaline solutions. It may also be due in part to a tanning effect on the emulsion by oxidized developing agent and in part to a localized exhaustion of alkali as a result of development.
  • the dye developer unreacted and diffusible, provides an imagewise distribution of unoxidized dye developer dissolved in a liquid processing composition as a function of the point-to-point degree of exposure of the silver halide emulsion.
  • At least part of this imagewise distribution of unoxidized dye developer is transferred by imbibition to a superposed image-receiving layer or element.
  • the layer of liquid processing composition may be utilized as the image-receiving layer.
  • the image-receiving element receives a depthwise diffusion of dye developer without appreciably disturbing the imagewise distribution thereof to provide the color transfer image.
  • the image-receiving element may contain agents adapted to mordant or other- Wise fix dye developer. If the color of the transferred dye developer is aifected by change in the pH of the image-receiving element, this pH may be adjusted to provide a pH affording the desired color.
  • the desired dye image carried by the image-receiving layer may be separated from the photosensitive element by stripping at the end of a suitable imbibition period.
  • the image-receiving layer need not be separated from its superposed contact with the photosensitive element, subsequent to transfer image formation, if the image-receiving element is transparent and a processing composition containing a substance effective to mask the exposed photosensitive element is spread between the image-receiving layer and the silver halide emulsion layer.
  • Dye developers are compounds "which contain in the same molecule both the chromophoric system of a dye and also a silver halide developing function.
  • a silver halide developing function is meant a grouping adapted to develop exposed silver halide.
  • a preferred silver halide developing function is a hydroquinonyl group.
  • Other suitable developing functions include ortho-dihydroxyphenyl and orthoand para-amino substituted hydroxyphenyl groups.
  • the development function includes a benzenoid developing function, that is, an aromatic developing group which forms quinonoid or quinone substances when oxidized.
  • the preferred dye developers comprise monoazo and anthraquinone dyes which possess one or two hydroquinonyl groups attached to the auxochromophobic system of the dye by means of a conjugationinterrupting divalent group such as, for example, an alkylene group.
  • Multicolored images may be obtained using color imageforming components, such as, for example, the previously mentioned dye developers, in diifusion transfer processes, by several techniques.
  • One such technique con-templates the use of a photosensitive silver halide stratum comprising at least two sets of selectively sensitized minute photosensitive elements arranged in the form of a photosensitive screen. Transfer processes of this type are disclosed in the previously noted U.S. Patent No. 2,983,606.
  • each of the minute photosensitive elements has associated therewith an appropriate dye developer in or behind a silver halide emulsion portion.
  • a suitable photosensitive screen prepared in accordance 'with the disclosure of said patent comprises minute red sensitized emulsion elements, minute green sensitized emulsion elements and minute blue sensitized emulsion elements arranged in side-by-side relationship in a screen pattern and having associated therewith, respectively, a cyan dye developer, a magenta dye developer and a yellow dye developer.
  • Another process for obtaining multicolor transfer images utilizing dye developers employs an integral multilayer photosensitive element such as is disclosed in the aforementioned U.S. Patents Nos. 2,983,606 and 3,345,- 163, wherein at least two selectively sensitized photosensitive strata and associated dye developers are superposed on a single support and are processed simultaneously and without separation with a single common imagereceiving layer.
  • a suitable arrangement of this type comprises a support carrying a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum, and a blue-sensitive silver halide emulsion stratum, said emulsions having associated therewith respectively, for example, a cyan dye developer, a magenta dye developer and a yellow dye developer.
  • the dye developer may be utilized in the silver halide emulsion layer, for example, in the form of particles, or it may be employed as a layer behind the appropriate silver halide emulsion stratum, for example, a layer of dye developer applied by the use of a coating solution containing about 0.5 to 8%, by weight, of the respective dye developer.
  • Each set of silver halide emulsion and associated dye developer strata may be separated from other sets by suitable interlayers, for example, gelatin and the synthetic polymeric materials disclosed in copending application of Lloyd D. Taylor, Ser. No. 641,669, filed Feb. 7, 1967 (now U.S. Patent No. 3,421,892 issued J an. 14, 1969).
  • suitable interlayers for example, gelatin and the synthetic polymeric materials disclosed in copending application of Lloyd D. Taylor, Ser. No. 641,669, filed Feb. 7, 1967 (now U.S. Patent No. 3,421,892 issued J an. 14, 1969).
  • a yellow filter in front of the green-sensitive emulsion and such yellow filter may be incorporated in an interlayer.
  • a yellow dye developer of appropriate spectral characteristics which is present in a state capable of functioning as a yellow filter may be employed. In such instances a separate yellow filter may be omitted.
  • the preceding color image-forming components are preferably selected for their ability to provide colors that are useful in carrying out subtractive color photography, i.e., cyan, magenta and yellow. It should be noted that it is within the scope of this invention to use mixtures of dye developers, for example, to obtain a desired color, e.g., black. Thus it is to be understood that the expression color as used herein is intended to include the use of a plurality of colors to obtain black, as well as the use of a single black dye developer.
  • US. Patent No. 3,362,819 discloses image-receiving elements, particularly adapted for employment in color diffusion transfer processes, for example, of the type disclosed in aforementioned US. Patent No. 2,983,606, which comprise a support layer possessing on one surface thereof, in sequence, a polymeric acid layer, an inert timing layer or spacer layer in the preferred embodiment, and an image-receiving layer adapted to provide a visible image upon transfer to said layer of diffusible dye image-forming substance.
  • the polymeric acid layer comprises polymers which contain acid groups, such as carboxylic acid and sulfonic acid groups, which are capable of forming salts with alkali metals, such as sodium, potassium etc., or with organic bases, particuuarly quaternary ammonium bases, such as tetramethyl ammonium hydroxide, or potentially acid-yielding groups, such as anhydrides or lactones, or other groups which are capable of reacting with bases to capture and retain them.
  • the acid-reacting group is, of course, nondiffusible from the acid polymer layer.
  • the acid polymer contains free carboxyl groups and the transfer processing composition employed contains a large concentration of sodium and/or potassium ions.
  • the acid polymers stated to be most useful are characterized by containing free carboxyl groups, being insouble in water in the free acid form, and by forming watersoluble sodium and/or potassium salts.
  • the acid polymer layer is disclosed to contain at least sufficient acid groups to effect a reduction in the pH of the image layer from a pH of about 12 to 14 to a pH of at least 11 or lower at the end of the im'bibition period, and preferably to a pH of about 5 to 8 Within a short time after imbibition.
  • the pH of the processing composition employed preferably is of the order of at least 12 to 14.
  • the pH of the image layer is kept at a level of pH 12 to 14 until the positive dye image has been formed after which the pH is reduced very rapidly to at least about pH 11, and preferably about pH 9 to 10, before the positive transfer image is separated and exposed to air.
  • Unoxidized dye developers containing hydroquinonyl developing radicals diffuse from the negative to the positive as the quaternary ammonium, sodium or other alkali salt.
  • the diffusion rate of such dye image-forming components thus is at least partly a function of the alkali concentration, and it is necessary that the pH of the image layer remain on the order of 12 to 14 until transfer of the necessary quantity of dye has been accomplished.
  • the subsequent pH reduction in addition to its desirable effect upon image light stability, serves a highly valuable photographic function by substantially terminating further dye transfer.
  • the processing technique thus effectively minimizes changes in color balance as a result of longer imbibition times in multicolor, transfer processes using multiplayer negatives.
  • the transfer image thus formed is unstable over an extended period of time.
  • the dye image instability is due, at least in part to the presence of what is, in general, a relatively high pH alkaline composition in intimate contact with the dye or dyes forming the image. This contact itself provides instability to the molecular structure of dye by, for example, catalyzing degradation and undesirable structural shifts effecting the spectral absorption characteristics of the image dye.
  • an alkaline composition possessing a pH at which the dye, for example, in reduced form, diffuses also provides an integral dynamic system wherein oxidized dye, immobilized in areas of the photosensitive element, as a function of its development, with the passage of time attempts to generate, in such areas, an equilibrium between oxidized and reduced dye.
  • the pH of the dynamic system is such that diffusion of the reduced form of the dye will occur, such reduced dye will, at least in part, transfer to the image-receiving layer and the resultant diffusion will imbalance the equilibrium, in such areas of the photosensitive element, in favor of additional formation of reduced dye.
  • the ultimate result is substantially the same overall image distortion as occurs when the image-receiving layer acts as a dye sink, with the exception that the dye is more extensively distributed ,throughout the film unit and the ultimate overall dyeing of the image-receiving layer itself is of lower saturation.
  • an integral photographic film unit particularly adapted for the production of a dye transfer image of unexpectedly improved stability and other properties, 'by a color diffusion transfer process will be constructed, for example, in accordance with aforementioned US. Pat. No. 3,415,644, to include a photosensitive element com prising a laminate having, in sequence, as essential layers, a dimensionally stable opaque layer; a photosensitive silver halide emulsion layer having associated therewith dye image-providing material which is soluble and diifusible, in alkali, at a first pH; an alkaline solution permeable polymeric layer dyeable by the dye image-providing material; a polymeric acid layer such as those disclosed in aforementioned U.S. Pat. No.
  • 3,362,819 containing sufficient acidifying groups to effect reduction, subsequent to substantial transfer dye image formation, of a selected processing solution having the first pH to a second pH at which said dye image-providing material is insoluble and nondiffusible; and a dimensionally stable transparent layer.
  • a rupturable container retaining an aqueous alkaline processing composition having the first pH and containing a material, preferably a reflecting agent, in a quantity sufficient to mask the dye image-providing material, is fixedly positioned and extends transverse a leading edge of the laminate whereby to effect unidirectional discharge of the containers contents between the alkaline solution permeable and dyeable polymeric layer and the photosensitive silver halide emulsion layer next adjacent thereto, upon application of compressive force to the container.
  • the dimensionally stable polymeric support layer next adjacent the photosensitive silver halide emulsion layer or layers may be transparent, as disclosed in aforementioned U.S. Patent No. 3,415,646, and that in such instance, the masking agent may be initially dispersed in the composite film unit intermediate the dyeable polymeric layer and the silver halide emulsion layer next adjacent, as disclosed in aforementioned U.S. Pat. No. 3,415,645.
  • the acid groups of the stated polymeric acid component are disclosed to be so distributed in the acid polymer layer that the rate of their availability to the alkali is controllable, e.g., as a function of the rate of swelling of the polymer layer which rate in turn has a direct relationship to the diffusion rate of the hydroxyl ions.
  • the desired distribution of the acid groups in the acid polymer layer may be effected by mixing the acid polymer with a polymer free of acid groups, or lower in concentration of acid groups, and compatible therewith, or by using only the acid polymer but selecting one having a relatively lower proportion of acid groups.
  • the layer containing the polymeric acid may contain a water insoluble polymer, preferably a cellulose ester, which acts to control or modulate the rate at which the alkali salt of the polymer acid is formed.
  • a water insoluble polymer preferably a cellulose ester
  • cellulose esters contemplated for use mention is made of cellulose acetate, cellulose acetate, butyrate, etc.
  • the particular polymers and combinations of polymers employed in any given embodiment are, of course, selected so as to have adequate wet and dry strength and when necessary or desirable, suitable subcoats may be employed to help the various polymeric layers adhere to each other during storage and use.
  • the inert spacer layer of the aforementioned patent acts to time" control the pH reduction by the polymeric acid layer.
  • This timing is disclosed to be a function of the rate at which the alkali diffuses through the inert spacer layer. It was stated to have been found that the pH does not drop until the alkali has passed through the spacer layer, i.e., the pH is not reduced to any significant extent by the mere diffusion into the spacer layer, but the pH drops quite rapidly once the alkali diffuses through the spacer layer into the acid polymer layer.
  • the last-mentioned inert spacer layer was found to provide an effective diffusion barrier timewise preventing effective traverse of the inert spacer layer by alkali having temperature depressed diffusion rates. This barrier resulted in maintenance of the transfer processing environrnents high pH for such an extended time interval as to facilitate formation of transfer image stain and its resultant degradation of the positive transfer images color definition.
  • Additional polymers which may be particularly advantageously employed are temperature-inverting polyvinylamide graft copolymers, as disclosed in copending application Ser. No. 790,147, 'filed Jan. 13, 1969, in the name of Lloyd D. Taylor (new U.S. Patent No. 3,575,701 issued Apr. 20, 1971).
  • an integral photographic film unit of simplified construction and particularly adapted for the production of dye transfer images of improved stability and other desirable properties by a color diffusion transfer process can be constructed to include a photosensitive element comprising a composite structure possessing, in sequence, as essential layers, a first dimensionally stable layer, a photosensitive silver halide emulsion layer having associated therewith a dyeimage-forming material which is soluble and diffusible at a first processing composition solvent concentration, a polymeric layer dyeable by the dye image-forming material, and a second dimensionally stable layer transparent to incident actinic radiation, wherein the dimensionally stable layers taken together, possess a processing composition solvent vapor permeability sufficient to effect, subsequent to substantial dye transfer image formation and preceding substantial dye transfer image degradation, osmotic transpiration of processing composition solvent in a quantity effective to decrease the first solvent concentration, at which the dye image-forming material is soluble and dilfusible, to a second solvent concentration, at which the dye image-forming material is substantially nondiffusible.
  • a rupturable container retaining a processing composition comprising the solvent is fixedly positioned and extends transverse a leading edge of the composite structure whereby to effect, upon application of compressive pressure, discharge of the processing composition intermediate the dyeable polymeric layer and the photosensitive silver halide emulsion layer next adjacent, in a quantity sufficient to provide the first solvent concentration.
  • an integral photographic film unit particularly adapted for the production of dye transfer images of improved stability and other desirable properties by a color diffusion transfer process can be con? structed to include a photosensitive element comprising a composite structure possessing, in sequence as essential layers, a first dimensionally stable layer, a photosensitive silver halide emulsion layer having associated therewith a dye image-forming material which is soluble and diffusible as a function of the point-to-point degree of emulsion photoexposure, a polymeric layer dyeable by the dye image-forming material, and a second dimensionally stable layer transparent to incident actinic radiation.
  • a photosensitive element comprising a composite structure possessing, in sequence as essential layers, a first dimensionally stable layer, a photosensitive silver halide emulsion layer having associated therewith a dye image-forming material which is soluble and diffusible as a function of the point-to-point degree of emulsion photoexposure, a polymeric layer dyeable by the dye image-forming material, and
  • a rupturable container retaining a processing composition is fixedly positioned and extends transverse a leading edge of the composite structure whereby to effect, upon application of compressive pressure, discharge of the processing composition intermediate the dyeable polymeric layer and the photosensitive silver halide emulsion and associated dye image-forming material next adjacent thereto.
  • the aforementioned integral photographic film unit possesses means for interposing between said dyeable polymeric layer and the photosensitive silver emulsion next adjacent thereto, a continuous dye image forming material impermeable polymeric layer after substantial image formation has been accomplished in said dyeable polymeric layer in order to obviate further dye migration.
  • Means for the formation of such a continuous polymeric layer include, for example, incorporating in the processing composition a particulate dispersion of a processing composition insoluble polymer as a discontinuous phase, said polymer being adapted, upon decrease in processing composition solvent, to coalesce at ambient temperature.
  • processing composition insoluble polymers suitable for such an application, mention may be made of the various polymeric solid and liquid materials which provide a latex when dispersed in a solvent in which they are insoluble and stable and, particularly when dispersed in water possessing a preselected pH, known in the art to coalesce at ambient temperatures and at relatively rapid rates upon loss of dispersant solvent to provide relatively impermeable substantially continuous films or polymeric layers including butadiene/ styrene copolymers; polyacrylamides; polymethylmethacrylates; polyvinyl chlorides and copolymers thereof; polyvinyl acetates and copolymers thereof; acrylonitrile/ethyl acrylate copolymers; acrylonitrile/styrene/butadiene terpolymers; and the like.
  • the permeability of such a material decreases to an ultimate point at which dye imageforming material is incapable of passing therethrough.
  • a pH valve Such a system may be visualized as a pH valve.
  • polymeric materials which may be used to provide a substantially continuous dye image-forming material impermeable stratum between the image-receiving layer and the photosensitive silver halide emulsion layer next adjacent thereto, mention may be made of the various polymeric materials which are known to act as a pH valve as aforenoted, such as, for example, polyphenolic polymers such as the acetal of hydroxybenzaldehyde and polyvinyl alcohol; sulfonamides, such as, for example, the acetal of a primary formyl benzene sulfonamide and polyvinyl alcohol; polymers comprising a-trifluoromethylvinyl alcohol segments; the benzene s'ulfonamide of deacetylated chitin; polyhydroxymethylene; the ace
  • such materials comprise weakly ionized polymeric acids, for example, those having an ionization constant between about 10- and 10
  • the above-denoted polymeric compositions whose permeability is directly related to the environmental pH may be utilized by being dissolved in the alkaline processing composition and being spread between the image-receiving layer and the next adjacent photosensitive layer to provide a substantially continuous stratum; or such materials may be coated intermediate the photosensitive silver halide emulsion next adjacent the image-receiving layer, and the image-receiving layer, as a continuous film to be rendered permeable at such time as the processing composition container is ruptured to thereby release the alkaline processing composition whereby the pH valve is rendered permeable to image-producing material until such time as the pH of the system is dropped below a dataum level.
  • the viscosityincreasing ingredients utilized in the processing composi tion are cross-linked subsequent to substantial image formation in the image-receiving layer to the extent required to provide an image-forming material impermeable layer between the image-receiving layer and the next adjacent silver halide emulsion layer.
  • Such a system may be carried out by incorporating a ditfusible cross-linking agent or suitable precursors thereof in the composite photosensitive structure, which, following rupture of the processing composition container, diffuse into distributed processing composition to thereby cross-link a thickening substance or other polymeric material incorporated in said processing composition.
  • hydroxyethyl cellulose is commonly utilized as a viscosity-increasing agent in conventional diffusion transfer processes, as more fully disclosed and discussed in numerous of the aforementioned patents and particularly in US. Pat. No. 2,983,606; suitable cross-linking agents for this and similar materials include divinyl s-ulfone and precursors thereof, e.g., bis-pyridinium ethyl sulfone chloride, and fl-ketoethyl onium salts as disclosed in Us. Pat. No. 3,345,177.
  • a still further technique for accomplishing the abovedenoted barrier formation as disclosed in copending application Ser. No. 867,583 is to provide a coating intermediate the dye image-forming layer and the photosensitive silver halide emulsion next adjacent thereto wherein a cross-linking agent for the material comprising said coating is incorporated in an element of the photographic film unit whereby after substantial image formation in the polymeric dye image-receiving layer sufiicient cross-linking agent contacts said coating to render it substantially impermeable to dye image-forming materials.
  • a polyvinyl alcohol overcoat may be utilized either over the image-receiving layer or over the next adjacent photosensitive silver halide layer, and a cross-linking agent therefor which will not have a substantial deleterious etfect on gelatin may be incorporated within one of the layers comprising the film unit, as, for example, in the denoted interlayer between the red-sensitive silver halide emulsion layer and the magenta dye developer layer.
  • a boric acid cross-linking agent for polyvinyl alcohol may be incorporated in the above-denoted interlayer.
  • processing composition Upon rupture of the processing composition container, processing composition is distributed between the image-receiving element and the negative element, rendering the boric acid material diifusible within the system. As this material comes into contact with the polyvinyl alcohol overcoat between the image-receiving layer and the next adjacent photosensitive emulsion layer, the polyvinyl alcohol is cross-linked and becomes impermeable to image-forming materials.
  • solution dyeable polymers such as nylons as, for example, N methoxymethyl polyhexamethylene adipa- 12 mide; partially hydrolyzed polyvinyl acetate; polyvinyl alcohol with or Without plasticizers; cellulose acetate with ifillers as, for example, one-half cellulose acetate and onehalf oleic acid; gelatin; and other materials of a similar nature.
  • Particularly useful materials have comprised polyvinyl alcohol or gelatin, having admixed therewith a dye mordant such as poly-4-vinylpyridine, as disclosed in US. Pat. No.
  • the liquid processing composition referred to for effecting monochromatic and multicolor transfer processes comprises at least an aqueous solution of an alkaline compound, for example, diethylamine, sodium hydroxide or sodium carbonate and possesses a pH in excess of 12 preferably.
  • an alkaline compound for example, diethylamine, sodium hydroxide or sodium carbonate
  • the liquid processing composition includes a viscosity-increasing compound consituting a film-forming material of the type which, when said composition is spread and dried, forms a relatively firm and relatively stable film.
  • a preferred filmforming material is a high molecular weight polymer such as a polymeric, water-soluble ether which is inert to an alkaline solution such as, for example, a hydroxyethyl cellulose or sodium carboxymethyl cellulose.
  • an alkaline solution such as, for example, a hydroxyethyl cellulose or sodium carboxymethyl cellulose.
  • Other filmforming materials or thickening agents whose ability to increase viscosity is substantially unaffected if left in solution for a long period of time may also be used.
  • the filmforming material is preferably contained in the processing composition in suitable quantities to impart to said composition a viscosity in excess of 1,000 centipoises at a temperature of approximately 24 C. and preferably of the order of 1,000 to 200,000 centipoises at said temperature.
  • liquid processing composition employed may contain an auxiliary or accelerating developing agent, such as p-methylaminophenol, 2,4-diaminophenol, p-benzylaminophenol, hydroquinone, toluhydroquinone, phenylhydroquinone, 4'-methylpl1enylhydroquinone, etc. It is also contemplated to employ a plurality of auxiliary or accelerating developing agents, such as a 3-pyrazolidone developing agent and a benzenoid developing agent, as disclosed in US. Pat. No. 3,039,869, issued June 19, 1962.
  • auxiliary developing agents examples include 1-phenyl-3-pyrazolidone in combination with p-benzylaminophenol and 1-phenyl-3-pyrazolidone in combination with 2,5-bis-ethyleneimino-hydroquinone.
  • auxiliary developing agents may be employed in the liquid processing composition or they may be initially incorporated, at least in part, in one or more permeable strata of the film unit. It may be noted that at least a portion of the dye developer oxidized during development may be oxidized and immobilized as a result of a reaction, e.g., an energytransfer reaction, with the oxidation product of an oxidized auxiliary developing agent, the latter developing agent being oxidized by the development of exposed silver halide. Such a reaction of oxidized developing agent with unoxidized dye developer would regenerate the auxiliary developing agent for further reaction with the exposed silver halide.
  • development may be desirably effected in the presence of an onium compound, particularly a quaternary ammonium compound, in accordance with the processes disclosed in US. Pat. No. 3,173,786.
  • color image quality may be enhanced by effecting development in the presence of imidazole, as disclosed in US. Pat. No. 3,377,166.
  • an antifoggant in a photographic system may be responsible for reducing both inherent and induced fog and will, therefore, produce a more attractive end product, both from aesthetic and technological points of view. Such products doubtless have a competitive advantage over other photographic products not quite as attractive or technologically efficient.
  • the antifoggant composition is particularly helpful in minimizing or preventing reaction of a dye developer with unexposed silver halide and may be added to the processing composition and/or to one or more processing composition permeable layers of the photosensitive and/ or image-receiving elements.
  • the pertinent art has recognized many compounds which have fog inhibiting characteristics, such as sodium and potassium bromide and iodide, 6-nitro-benzimidazole, benzotriazole, chlorobenzotriazole, S-methyl-benzimidazole, 2-amino-benzimidazole, thio acetanilide, etc.
  • azabenzimidazole antifoggants may be used alone or in conjunction with other conventional antifoggants.
  • the azabenzimidazole antifoggants were utilized in conjunction with a conventional antifoggant compound, such as benzotriazole, whose effectiveness responds normally to changes in temperature, to provide to the system development and control characteristics satisfactory over a greater temperature range than that achieved by the teachings set forth in the art.
  • a conventional antifoggant compound such as benzotriazole
  • antifoggant comprising a first azabenzimidazole consisting of 5-hydroxy-4-azabenzimidazole in combination with a second azabenzimidazole of the formula:
  • R is selected from the group consisting of hydrogen and lower alkyl groups, i.e., containing less than six carbon atoms; and R and R are each selected from the group consisting of hydrogen, halogen, lower alkyl, i.e., containing less than six carbon atoms, nitro, lower alkoxy i.e., containing less than six carbon atoms, aryl, sulfonamido, and carboxamido groups, it being understood that R and R taken together may form an annulated hydrocarbon ring system, in diffusion transfer photographic processes of the type described, results in a wider exposure range over which useful information may be effectively recorded in the processed positive print.
  • a photosensitive element which is specifically adapted to provide for the production of a multicolor dye transfer image and comprises a dimensionally stable support layer carrying at least two selectively sensitized silver halide emulsion strata each having a dye developer material of predetermined color associated therewith which is soluble and diffusible in alkali at a first pH.
  • the preferred photosensitive image-receiving element comprises an alkaline solution permeable polymeric layer dyeable by the dye developer; a polymeric spacer layer comprising a polymer possessing decreasing alkaline solution permeability with increasing temperature; an alkaline solution permeable polymeric acid layer containing sufiicient acidifying groups to effect reduction, subsequent to substantial multicolor transfer dye image formation, of the image-receiving element from the first pH- to a second pH, at which the dye image-providing material is insoluble and nondiffusible; and a dimensionally stable support layer.
  • the silver halide emulsions comprising the multicolor photosensitive laminate preferably possess predominant spectral sensitivity to separate regions of the spectrum and each has associated therewith a dye, which is a silver halide developing agent and is, most preferably, substantially soluble in the reduced form only at the first pH, possessing a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion.
  • a dye which is a silver halide developing agent and is, most preferably, substantially soluble in the reduced form only at the first pH, possessing a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion.
  • each of the emulsion strata, and its associated dye is separated from the remaining emulsion strata, and their associated dye, by separate alkaline solution permeable polymeric interlayers.
  • the silver halide emulsion comprises photosensitive silver halide dispersed in gelatin and is about 0.6 to 6 microns in thickness; the dye itself is dispersed in an aqueous alkaline solution polymeric binder, preferably gelatin, as a separate layer about 1 to 7 microns in thickness; the alkaline solution permeable polymeric interlayers are about 1 to 5 microns in thickness; the alkaline solution permeable and dyeable polymeric layer is transparent and about 0.25 to 0.4 mil in thickness; the polymeric spacer layer intermediate the dyeable polymeric layer and the polymeric acid layer is transparent and about 0.1 to 0.7 mil in thickness; the alkaline solution permeable polymeric acid layer is transparent and about 0.3 to 1.5 mils in thickness; and each of the dimensionally stable support layers are alkaline solution impermeable and about 2 to 6 mils in thickness.
  • the relative dimensions recited above may be appropriately modified, in accordance with the desires of the operator, with respect to the specific
  • the respective silver halide/dye developer units of the photosensitive element will be in the form of a tripack configuration which will ordinarily comprise a cyan dye developer/red-sensitive emulsion unit contiguous the dimensionally stable support layer, the yellow dye developer/blue-sensitive emulsion unit most distant from the support layer and the magenta dye developer/ green-sensitive emulsion unit intermediate those units, recognizing that the relative order of such units may be varied in accordance with the desires of the operator.
  • FIG. 1 of the drawing wherein there is illustrated a preferred film unit of the present invention.
  • film unit 10 comprises a photosensitive laminate 11 including, in order, dimensionally stable support layer 12, preferably a flexible sheet material; cyan dye developer layer 13; red-sensitive silver halide emulsion layer 14; interlayer 15, magenta dye developer layer 16; green-sensitive silver halide emulsion layer 17; interlayer 18; yellow dye developer layer 19; blue-sensitive silver halide emulsion layer 20; auxiliary layer 21, which may contain an auxiliary silver halide developing agent; and an image-receiving element 22 including image-receiving layer 23; spacer layer 24; neutralizing layer 25; and dimensionally stable support layer 26, preferably a flexible sheet material.
  • the multilayer exposed photosensitive element 11 is shown in processing relationship with an image-receiving element 22 and a layer 27 of processing solution distributed intermediate elements 11 and 22.
  • the unit In the performance of a diffusion transfer multicolor process employing film unit 10, the unit is exposed to radiation, actinic to photosensitive laminate 11.
  • film unit 10 may be processed by being passed through opposed suitably gapped rolls in order to apply compressive pressure to a frangible container in order and to effect rupture of the container and distribution of alkaline processing composition 27, having a pH at which the cyan, magenta and yellow dye developers are soluble and difiusible, intermediate dyeable polymeric layer 23 and auxiliary layer 21.
  • Alkaline processing solution 27 permeates emulsion layers 14, 17 and 20 to initiate development of the latent images contained in the respective emulsions.
  • the cyan, magenta and yellow dye developers, of layers 13, 16 and 19, are immobilized, as a function of the development of their respective associated silver halide emulsions, preferably substantially as a result of their conversion from the reduced form to their relatively insoluble and nondiffusible oxidized form, thereby providing imagewise distributions of mobile, soluble and diffusible cyan, magenta and yellow dye developer, as a function of the point-to-point degree of their associated emulsions exposure.
  • At least part of the imagewise distributions of mobile cyan, magenta and yellow dye developer transfers, by diffusion, to aqueous alkaline solution permeable polymeric layer 23 to provide a multicolor dye transfer image to that layer.
  • a suflicient portion of the ions comprising aqueous alkaline solution 27 transfers, by diffusion, through permeable polymeric layer 23, permeable spacer layer 24 and to permeable polymeric acid layer 25
  • alkaline solution 27 decreases in pH, as a function of neutralization, to a pH at which the cyan, magenta and yellow dye developers, in the reduced form, are insoluble and nondiffusible, to provide thereby a stable multicolor dye transfer image.
  • print-receiving element 22 may be manually dissociated from the remainder of the film unit, for example, by stripping.
  • print-receiving element 22 need not be dissociated from the remainder of the film unit, but may be maintained in superposed relationship thereto; the final positive image is then viewable through transparent support layer 26.
  • reflecting materials mention may be made of barium sulfate, zinc oxide, titanium dioxide, barium stearate, silver flake, silicates, alumina, zirconium oxide, zirconium acetyl acetate, sodium zirconium sulfate, kaolin, mica, and the like.
  • a particularly preferred agent comprises titanium di oxide due to its highly effective reflection properties.
  • a processing composition containing about 40- 70 grams of titanium dioxide dispersed in 100 cc. of water Will provide a percent reflectance of about -90% In the most preferred embodiments, the percent reflectance particularly desired will be in the order of above 85%.
  • the American Standards Association, Incorporated has established standards for quantitative evaluation of the sensitivity of photosensitive materials. These standards specify techniques for plot-ting the characteristic H and D curve of a negative material, that is, the curve relating to the logarithm of the original exposure of the negative to density in said negative. These techniques are described in detail in the publication of the American Standards Association, Incorporated, PH 2.5-1954, and titled American Standard Method for Determining Photographic Speed and Exposure Index. In diffusion transfer processes, a similar evaluation of reflection prints may be based on a curve relating original exposure of the negative to the density in the resultant positive, i.e., a curve plotting the reflecting density of the positive as a function of the log exposure of the negative.
  • the Dynamic Range of a diffusion transfer image comprises an empirically derived relative measurement of the range of exposure from which a useful transfer image may be derived. This range is determined by subtracting the log exposure value determined at the point on the toe portion of the transfer images characteristic curve where the gradient is 0.4from the log exposure value determined at the point on the shoulder portion of the curve, where the gradient is 0.4. The resultant gradient range is then equivalent to the log of the ratio of the 0.4 toe gradient to the 0.4 shoulder gradient in units of exposure. The anti-log of the resultant exposure gradient provides the ratio of minimum to maximum exposure in a subject which can be usefully recorded by the film and is designated as the Dynamic Range.
  • the speed of the photosensitive material comprises generally an empirically derived relative measurement which may be defined as a value representing the reciprocal of the exposure required to produce a given result. Any precise valuation of speed," therefore, is based upon the selection of a particular reference point on the density scale of the characteristic curve for the material.
  • shoulder speed is the minimum amount of exposure which can be used to expose the negative emulsion and give a transfer image in which there is the minimum contrast which the eye can distinguish, i.e., there is visible detail in the shadow regions of the transfer image. This exposure is determined at the point on the shoulder portion of the previously described characteristic curve of the positive transfer image where the gradient is 0.4.
  • 0.6 speed refers to the amount of exposure needed to result in a positive transfer image having a density of 0.6 on the density scale of the characteristic curve.
  • the toe of the characteristic curve of a positive transfer image refers to the point in the curve where the system begins to respond to reduce exposure from high intensity to lower intensities.
  • the toe extent refers to that portion of the characteristic curve of a positive transfer image wherein the eye can begin to distinguish" density differences in the image at high intensity exposures, and may be determined by the horizontal distance between the point on the toe portion of the curve where the gradient is 1.0 and the point on the toe portion of the curve where the gradient is 0.2.
  • the slope of designated central portions of the characteristic curve of a position transfer image may be used as an indication of the tonal range of these portions of the system; thus, a low slope value is indicative of a film having the ability to record a large range of tones, whereas a higher slope value reflects'a correspondingly smaller range of tones.
  • two slope values are indicative of a film having the ability to record a large range of tones, whereas a higher slope value reflects'a correspondingly smaller range of tones.
  • A- A1 slope and -40 normalized slope.
  • the A% slope may be determined by the formula:
  • Y is the point on the density scale corresponding to D
  • D D X is the exposure needed to result in the density represented by the value Y
  • X is the exposure resulting in the density represented by the value Y
  • the 9040 normalized slope is a similar measurement, but which enables a more direct comparison of the tonal ranges of positive color images having different color saturations and densities; it may be determined by the formula D max. unn.
  • S9040 is the slope of the curve between the .9 and .4 density intercepts.
  • EXAMPLE 1 An image-receiving element was prepared by coating a transparent polyethylene terephthalate base with the partial butyl ester of polyethylene/maleic anhydride copolymer prepared by refluxing, for 14 hours, 300 g. of a DX-84031 resin (trade name of Monsanto Chemical Co., St. Louis, Mo., for high viscosity polyethylene/maleic anhydride), g. of n-butyl alcohol and 1 cc. of 85% phosphoric acid to provide a polymeric acid layer approximately 0.7 mil thick.
  • a DX-84031 resin trade name of Monsanto Chemical Co., St. Louis, Mo.
  • the external surface of said acid layer was coated with an emulsion comprising a graft copolymer of diacetone acrylamide and acrylamide on polyvinyl alcohol at a coverage of 750 mg./ft. to provide a spacer layer.
  • a spacer layer Spacer layers for diffusion transfer color image-receiving elements comprising graft vinylamide copolymers and procedures for preparing such polymers are described in copending application Ser. No. 790,747, filed Jan. 13, 1969, in the name of Lloyd D. Taylor.
  • the external surface of thespacer layer was then coated with a 2:1 mixture, by weight, of polyvinyl alcohol and poly-4- vinylpyridine, at a coverage of approximately 600 mgs. per square foot, to provide a polymeric image-receiving layer approximately 0.40 mil thick.
  • the thus-prepared image-receiving element was then baked at F. for 30 minutes and then allowed to cool.
  • a multicolor, multilayer photosensitive element was prepared in a manner similar to that disclosed in the aforementioned U.S. Patent No. 3,345,163 and detailed hereinbefore.
  • the photosensitive elements comprised a support carrying a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum and a blue-sensitive silver halide emulsion stratum.
  • the emulsions had dispersed behind'them in water: immiscible organic solvents and contained in separate gelatin polymeric layers, respectively, a cyan dye developer, a magenta dye developer and a yellow dye developer.
  • a vinyl amide polymer interlayer was positioned between the yellow dye developer layer and the greensensitive emulsion stratum, and also between the magenta dye developer layer and the red-sensitive emulsion stratum.
  • Interlayers for diffusion transfer color photosensitive elements comprising vinyl amide polymers and procedures for preparing such polymers are described in U.S. Patent No. 3,575,700 issued Apr. 20, 1971 on copending application Ser. No. 790,648, filed Jan. 13, 1969, in the name of Lloyd D. Taylor.
  • dye developers employed were metal-complexed dye developers of the following formulae:
  • no-cm-cm N-SOz- N N "-011, HO-CHz-CH: l N 1?/ ⁇ eo if 0 O-c-omama magenta dye developer;
  • the photosensitive element was then exposed to an analytical target, and processed for three minutes at room temperature by spreading a processing composition comprising:
  • the resulting positive image showed a D of 2.21 (red), 2.15 (green), and 1.93 (blue) and a D of .05 (red), .19 (green), and .24 (blue), and exhibited the following characteristics:
  • Example 5 The process of Example 2 was repeated, except that 6 bromo 5 methyl 4 azabenzi-midazole was omitted altogether from the processing composition, and 1.72 g. of phenethylpicolinium bromide per cc. of water was employed. The resulting positive image exhibited the following characteristics:
  • Example 3 The process of Example 3 was repeated, except that hydroxy 4 azabenzimidazole was omitted altogether from the processing composition.
  • the resulting positive image exhibited the following characteristics:
  • FIG. 2 shows characteristic curves of the red components of the transfer images prepared in Examples 3 and 6, wherein Curve A (solid line) represents the characteristic curve of the red component of the transfer image of Example 3, and Curve B (broken line) represents the characteristic curve of the red component of the transfer image of Example 6.
  • Curve A solid line
  • Curve B broken line
  • Example 3 Experiments similar to that of Example 3 were conducted using 6-methyl-4-azabenzimidazole in combination with 5-hydroxy-4-azabenzimidazole. It was observed that the resulting transfer images exhibited results similar to those obtained in Example 3, particularly with respect to greater dynamic range, faster 0.6 speed, and lower stain as compared with control experiments not containing 5-hydroxy-4 azabenzimidazole. Similar results were obtained in experiments wherein the antifoggant component comprised a combination of 6 chloro-4-azabenzimidazole and 5-hydroxy-4-azabenzimidazole.
  • the optimum concentration of the total antifoggant component to be employed should be determined empirically for each specific photographic system. In general, such concentration range is between 0.005 to 5.0 mgs. per millimole of silver halide present in the silver halide emulsion of concern, depending on the fogging characteristics of the silver halide emulsion. In a preferred embodiment, the incorporation of from between about 0.15 to 2.0 g. of the combination of compounds of the present invention per 100 cc. of the processing composition utilized in the diifusion transfer photographic process, provides particularly desirable results. Although con centrations in excess of the first mentioned range may be employed, an increase in the concentration beyond the designated limits generally provides no additional beneficial results. Conversely, concentrations below that of the designated range merely decrease fog control below the effective levels generally sought, but do not negate the achievement of some beneficial fog control.
  • the agents themselves may be initially disposed in any one or more processing composition permeable layers of the film nnits photosensitive and/or image-receiving elements, for example, at any stage during its manufacture, in supplementation of, or in replacement of, the previously illustrated disposition as a component of the processing composition.
  • the support layers referred to may comprise any of the various types of conventional rigid or flexible supports, for example, glass, paper, metal, and polymeric films of both synthetic types and those derived from naturally occurring products.
  • Suitable materials include paper; polymethacrylic acid, methyl and ethylesters; vinyl chloride polymers; polyvinyl acetal; polyamides such as nylon; polyesters such as polymeric films derived from ethylene glycol terephthalic acid and cellulose derivatives such as cellulose acetate, triacetate, nitrate, propionate, butyrate, acetate-propionate, or acetate-butyrate.
  • silver halides of varying halide concentrations may be advantageously employed and that the silver halide emulsions employed may be sensitized chemically and optically by any of the accepted procedures.
  • a rupturable container provides a convenient means for spreading a liquid processing composition between layers of a film unit whereby to permit the processing to be carried out within a camera apparatus
  • the practices of this invention may be otherwise effected.
  • a photosensitive element after exposure in suitable apparatus and while preventing further exposure thereafter to actinic light, may be removed from such apparatus and permeated with the liquid processing composition, as by coating the composition on said photosensitive element or otherwise wetting said element with the composition, following which the permeated, exposed photosensitive element, still, without additional exposure to actinic light, is brought into contact with the image-receiving element for image formation in the manner heretofore described.
  • the expression positive image has been used. This expression should not be interpreted in a restrictive sense since it is used primarily for purposes of illustration, in that it defines the image produced on the image-carrying layer as being reversed, in the positive-negative sense, with respect to the image in the photosensitive element.
  • the expression positive image assume that the photosensitive element is exposed to actinic light through a negative transparency. In this case, the latent image in the photosensitive element will be a positive and the image produced on the image-carrying layer will be a negative.
  • the expression positive image is intended to cover such an image produced on the image-carrying layer.
  • a process for forming a photographic silver image which comprises the step of developing an exposed photosensitive element containing a silver halide emulsion with an aqueous processing composition, the improvement which comprises conducting said process in the presence of an eifective amount of an antifoggant composition comprising the combination of a first azabenzimidazole consisting of S-hydroxy-4-azabenzimidazole and a second azabenzimidazole of the formula wherein R is hydrogen or a lower alkyl group; and R and R are each hydrogen, halogen, lower al-kyl, nitro, lower alkoxy, aryl, sulfonamido, or carboxamido groups.
  • a process as defined in claim 1 which includes the steps of developing said exposed photosensitive element with an aqueous alkaline diffusion transfer processing composition; forming thereby an imagewise distribution of image-forming components in said photosensitive element, as a function of the point-to-point degree of exposure thereof; and transferring at least part of said imagewise distribution, by diffusion, to a contiguous imagereceiving layer to provide thereto a photographic diffusion transfer image.
  • color image-forming components comprise a dye which is a silver halide developing agent.
  • a process for forming transfer images in color which includes, in combination, the steps of exposing a photosensitive element which comprises at least two selectively sensitized silver halide emulsion layers each having a dye of predetermined color associated therewith, which dye is a silver halide developing agent and is soluble and diffusible in alkali; contacting said exposed photosensitive element with an aqueous alkaline processing composition; effecting thereby development of the latent images contained in each of said silver halide elements; immobilizing the dye associated with each of said emulsions as a result of development; forming thereby an imagewise distribution of mobile dye, as a function of the point-to-point degree of exposure thereof; and transferring, by imbibition, at least a portion of each of said imagewise distributions of mobile dye to a superposed image-receiving element to provide thereto a multicolor dye transfer image.
  • a process of forming transfer images in color which includes, in combination, the steps of exposing a photosensitive element comprising blue-sensitive, green-sensitive, and red-sensitive gelatino silver halide emulsion layers mounted on a common support, said blue-sensitive, green-sensitive, and red-sensitive silver halide emulsion layers having associated therewith, respectively, yellow, magenta, and cyan dyes, each of said dyes being a silver halide developing agent soluble and difiusible in alkali; contacting said exposed photosensitive element with an aqueous alkaline processing composition;
  • each 'silver halide emulsion immobilizing said yellow, magenta, and cyan dye, as a function of development of their respective associated silver halide emulsion; forming thereby an imagewise distribution of mobile yellow, magenta, and cyan dye; and transferring, by imbibition, at least a portion of each of said imagewise distributions of mobile dye to a superposed image-receiving element to provide thereto a multicolor dye transfer image.
  • a process as defined in claim 10 wherein said second azabenzimidazole is 6-bromo-5-methyl-4-azabenzimidazole.
  • a process as defined in claim 10 wherein said second azabenzimidazole is 6-methyl-4-azabenzimidazole.
  • a process as defined in claim 10 wherein said second azabenzimidazole is 6-chlo ro-4-azabenzimidazole.
  • a process as defined in claim 10 wherein the mole ratio of said 5-hydroxy-4-azabenzimidazole to said second azabenzimidazole is from about 1:0. 14 to about 1:20.
  • a process as defined in claim 10 wherein said anti foggant composition includes benzotriazole.
  • a photosensitive element which comprises a support layer carrying a photosensitive silver halide emulsion having associated therewith an antifoggant composition comprising the combination of a first azabenzimidazole consisting of 5-hydroxy-4-azabenzimidwherein R is hydrogen or a lower alkyl group; and R and R are each hydrogen, halogen, lower alkyl, nitro, lower alkoxy, aryl, sulfonamido, or carboxamido groups.
  • a photosensitive element as defined in claim 17 wherein the mole ratio of said 5-hydroxy-4- azabenzimidazole to said second azabenzimidazole is from about 1:0.14 to about 1:20.
  • each of said selectively sensitized photosensitive emulsion layers has predominant spectral sensitivity to separate regions of the spectrum and the dye associated with each of said emulsion layers possesses a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsionlayer.
  • a photographic fihn unit as defined in claim 27 including a rupturable container retaining an aqueous alkaline processing composition afiixed one edge of one of said photosensitive and said image-receiving elements and adapted upon rupture to distribute its contents intermediate said photosensitive element and said imagereceiving element upon super-positioning of said elements.
  • a photographic film unit as defined in claim 26 including a diffusion transfer image-receiving element affixed at least one edge of said photosensitive element and a rupturable container retaining an aqueous alkaline processing composition containing said antifoggant composition afiixed one edge of at least one of said photosensitive and said image-receiving elements and adapted upon rupture to distribute its contents intermediate said photosensitive element and said imagereceiving element upon super-positioning of said elements.
  • a film unit as defined in claim 30 wherein said antifoggant composition includes benzotriazole.

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