US3617275A

US3617275A - Differential color moiety mobility in monochromatic diffusion-transfer elements and processes

Info

Publication number: US3617275A
Application number: US12944A
Authority: US
Inventors: Stanley M Bloom; Joel M Peisach; Robert K Stephens
Original assignee: Polaroid Corp
Current assignee: Polaroid Corp
Priority date: 1970-02-20
Filing date: 1970-02-20
Publication date: 1971-11-02
Anticipated expiration: 1988-11-02

Abstract

Novel systems for preparing dye images utilizing novel elements including a dyeable stratum and a layer containing a colorproviding material which is nondiffusible but upon oxidation can release a diffusible color-providing moiety for transfer to the dyeable stratum to impart thereto a color transfer image.

Description

United States Patent [72] Inventors Stanley M. Bloom Joel M. Peisach, Hudson; Robert K. Stephens, Burlington, all of Mass.

Polaroid Corporation Cambridge, Mass.

DIFFERENTIAL COLOR MOIETY MOBILITY IN MONOCIIROMATIC DIFFUSION-TRANSFER ELEMENTS AND PROCESSES 15 Claims, 1 Drawing Fig.

US. Cl

Primary Examiner-Norman G. Torchin Assistant Examiner-Alfonso T. SuroPico Attorneys-Brown and Mikulka and Alvin lsaacs ABSTRACT: Novel systems for preparing dye images utilizing novel elements including a dyeable stratum and a layer containing a color-providing material which is nondiffusible but upon oxidation can release a diffusible color-providing moiety for transfer to the dyeable stratum to impart thereto a color transfer image.

SUPPORT 5 PROCESSING COMPOSITION SILVER HALI DE LAYER COLOR-PROVIDING MATERIAL STRIPPING LAYER [\-DYEABLE STRATUM PSUPPORT PATENIED NUV2 I97! -suPPoRT -S|LVER HALI DE LAYER PROCESSING COMPOSITION COLOR-PROVIDING MATERIAL 'STRIPPING LAYER DYEABLE STRATUM ----SUPPORT I N VENTORS STA d JOEL M. PEISACH and BY ROBER .STEPHENS 6mm m wrwl I M fmw ATTORNEYS Y M. BLOOM DIFFERENTIAL COLOR MOIETY MOBILITY IN MONOCHROMATIC DIFFUSION-TRANSFER ELEMENTS AND PROCESSES BACKGROUND OF THE INVENTION The copending application of Stanley M. Bloom, Ser. No. 655,338 tiled July 24, 1967, describes and claims novel compounds containing a color-providing moiety and an anchoring" or immobilizing moiety. These compounds are immobile and nondiffusible in anaqueous alkaline; medium, but are capable of providing, upon oxidation, an oxidation product which may autoreact intramolecularly to form a heterocyclic ring and, as a function of this ring formation, to split off a mobile and diffusible color-providing material. This reaction may also be defined as a ring-closure of the oxidation product resulting in a separation or freeing of the mobile color-providing moiety from the anchoring moiety."

US. Pat. No. 3,443,939 issued to Stanley M. Bloom and Robert K. Stephens discloses systems employing the aforementionednondifi'usible compounds to obtain negative color transfer images. According to. this copending patent application a photosensitive element containing at least one light-sensitive silver halide emulsion and associated compound of the foregoing description is exposed and then developed with an aqueous alkaline processing composition including a silver ha,- lide developing agent which upon development providestan oxidation product capable of being reduced by a redox reac tion with the aforementioned compound, the developer further being sufficiently mobile in its oxidized state so as to be capable of migrating to the layer containing the colorproviding compound; oxidizing the developing agent as a function of development to provide an imagewise distribution of oxidized developing agent in terms of exposed and developed areas of the emulsion; transferring this imagewise distribution at least in part, to contact the color-providing compound, whereby a redox reaction takes place to reducethe developing agent and to oxidize the color-providingcompound to form an oxidation product which then ring-closes to split off the mobile color-providing moiety in turn to form an imagewise distribution of mobile and diffusible color providing compound in terms of exposed areas of the emulsion; and transferring this latter imagewise distribution, at least in part, by imbibition, to a superposed dyeable stratum to impart: thereto a negative color transfer image.

SUMMARY OF THE INVENTION The present invention is directed to novel products and systems utilizing the procedures described in the aforementioned US. Pat. No. 3,443,939.

In accordance with the present invention use is made of a structure comprising a support. carrying a dyeable stratum and a layer of the aforementioned color-providing material, a stripping layer preferably but not necessarily being disposed therebetween. When a photosensitive element comprising a support containing a light-sensitive silver halide layer, e.g,,, high speed gelatino silver halide emulsion, is photoexposed to provide a developable image and this image is then developed, by spreading between the thus exposed element and the aforementioned element containing the color-providing material and dyeable stratum an aqueous alkaline processing composition including a silver halide developing agent, the oxidation product of which is capable of entering into the aforementioned redox reaction with the color providing material, the color-providing moiety is released and a dye transfer image is imparted to the dyeable stratum.

The present invention provides certain advantages over the product structures described in US. Pat. No. 3,443,939

wherein the color providing material is contained in a layer on the photosensitive element, chief of which is the ability to obtain dye images of greater resolution. This andother advantages will be stated in greater particularity hereinafter.

The present invention is particularly useful in color radiography, e.g., in the preparation of negative X-ray transpareneies.

BRIEF DESCRlPTlON OF DRAWING The FIG. is a partially schematic, enlarged, fragmentary sectional view illustrating the products and photographic systems of this invention.

DESCRIPTION OF PREFERRED EMBODIMENT The preferred embodiment is directed to the formation of color transparencies and the support for the dyeable stratum is accordingly substantially transparent. As wasv mentioned previously, a stripping layer is preferably disposed between this stratum and the layer of color-providing material to facilitate clean separation of the color image. following development.

As was mentioned previously, this invention relates to photography and, more particularly, to novel products and processes for forming color images.

A primary object of this invention, therefore, is to provide novel products and processes of the foregoingdescription.

Another object is to provide novel procedures utilizing as the color-providing material, a nondiffusible compound containing a diffusible color-providing moiety, e.g., a diffusible dye moiety, which compound is capableof forming by a redox reaction with oxidized, silver halide developing agent an oxidization product which can autoreact intra-molecularly to effect ring-closure and'to eliminate the diffusible color-providing moiety of the compound for transfer.

Yet another object is to provide novelproducts including a support carrying a dyeable stratum and a layer carrying a color-providing material of the foregoing description, which products may be employed in conjunction with a photosensitive element comprising asupport carrying a light-sensitive silver halidelayer in photographic processes for forming color transfer images.

Still another object is to provide novel products and processes for preparing negative color images, e.g.. color transparencies, of excellent resolution and density.

A still further object is'to provide novel procedures for. preparing color radiographs.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation and order of one or more of such steps with respect to eachof the others and the product possessing the features, properties and the relation of elements which are exemplified in thefollowing detailed disclosure, and the scope of the application otI-which will be indicated in the claims,

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing.

As was mentioned previously, the present invention utilizes as the color image-forming components compounds containing a color-providing moiety and an anchoring or immobilizing moiety, which are described and claimed in the aforementioned copending application, Ser. No. 655,338. These compounds are immobile and,nondiffusible in anaqueous alkaline medium, but are capable of providing, upon oxidation, anoxwherein:

A and A each represent the atoms necessary to complete abenzene or naphthalene ring, which ring may be further substituted;

D is a color-providing moiety, e.g., a complete dye such as a monoazo, disazo or anthraquinone dye which may, if desired, be metallized in known manner;

Y is any substituent which completes or forms an amide with, and reduces the basic character of the amino group in the 3-position, such as the residue of an acid, linking the colorproviding moiety D to the 3-nitrogen atom, and which is capable of being eliminated during the ring formation to be described with more particularity hereinafter, e.g.,

etc.;

R and R each represent an anchoring" or immobilizing substituent rendering the compound nondiffusible, e.g., higher alkyl such as decyl, dodecyl, stearyl, oleyl, etc. linked directly to the aromatic nucleus or linked indirectly thereto through an appropriate linking group, e.g., CONH,

etc., an aromatic ring, e.g., of the benzene or naphthalene series, or a heterocyclic ring, which rings may be either bonded to a single carbon atom of the aromatic nucleus or fused thereto, i.e., bonded to a pair of adjacent carbon atoms; or R and/or R may be a plurality of short chain radicals which together provide the anchoring moiety, each of said short chain radicals being linked directly or indirectly to a different carbon atom of the aromatic nucleus formed by the A and/or A moieties;

X is hydrogen, hydroxy, amino, e.g., a primary, secondary or tertiary amino substituent of the formula:

wherein each R may be hydrogen, a hydrocarbon radical, e.g., alkyl, such as methyl, ethyl, butyl, dodecyl, etc., aryl such as phenyl or naphthyl attached through a carbon atom thereof to the nitrogen atom, a cyclic alkyl such as cyclopentyl or cyclohexyl, i.e., where both R s are alkylene comprising together with the nitrogen atom a heterocyclic ring, a substituted alkyl, such as hydroxyethyl, methoxyethoxyethyl, polyglycoloxyethyl, carboxymethyl, benzyl, phenylethyl, sulfo-phenylethyl, acetylaminophenylethyl, succinylaminophenylethyl, furanemethyl, etc.; or a substituted aryl such as methylphenyl, ethylphenyl, etc., or the anchoring substituent X is hydrogen, hydroxy, an amino group such as may be contained by said X moiety, as previously described, or the anchoring substituent R", provided that one of said X and X moieties must be hydroxy or amino;

R is hydrogen, an alkyl such as methyl, ethyl, propyl, butyl, hexyl, octyl, dodecyl, cyclohexyl, etc.; or a substituted alkyl such as 2-hydroxyethyl, 3-dihydroxypropyl, carboxymethyl, carboxyethyl, carboxybutyl, carboxydecyl, hydroxyethylether, polyglyeoloxyethyl, furanemethyl, benzyl, phenylethyl, carboxyphenylethyl, sulfo-phenylethyl, acylaminophenylethyl, etc.; and

n and n each is a positive integer from 1 to 2, provided that when R or R alone or together comprise one of those hereto fore named substituents rendering the compound nondiffusible, either or both of n and n may be I but when R' and R alone or together do not provide such an anchoring moiety at least one ofn and n must be 2.

Preferred are those compounds within the scope of the above formula which are of the following formula:

wherein the anchoring moiety R or R comprises a long chain amide, e.g., of at least 13 carbon atoms; and nuclear substituted derivatives thereof, e.g., where any of the nuclear carbon atoms not specifically substituted may contain a carboxy, alkyl, alkoxy, amino, chloro, hydroxy or amide substituent.

The present invention utilizes the principles described and claimed in the aforementioned U.S. Pat. No. 3,443,939 to effect transfer of such a color providing material to a dyeable stratum to impart thereto a negative color image, the essence of the invention being providing the layer of color-providing material on the image-receiving element as distinguished from providing it on the photosensitive element, i.e., providing the color-providing material in a layer on the support carrying the dyeable stratum on which the negative color image is to be formed, in order to provide certain significant advantages.

The invention will be more readily understood by reference to the accompanying drawing.

As shown in the FlG., a novel product of this invention comprises a support 10 carrying on one side thereof a dyeable stratum 12, a stripping layer 14 and a layer 16 containing a color-providing material of the foregoing description, e.g., of formulas A or B, which materials are described and claimed in the aforementioned copcnding application, Ser. No. 655,338.

Support 10 may be transparent or opaque, depending upon whether transparencies or reflection prints are contemplated. It may even be translucent so as to provide a support or base sheet for an image viewable either as a reflection print or as a transparency. in any event, it may comprise any of the support materials heretofore employed for such purposes. By way of illustration, it may be made of cellulose nitrate, cellulose acetate, polyvinyl acetal, polystyrene, polyethylene terephthalate, polyethylene, polypropylene, polycarbonate, etc., paper, glass or other materials. Translucency may be obtained with any of the foregoing transparent materials by application of a layer ofa suitable white pigment, e.g., titanium dioxide.

As was mentioned previously, the present invention is particularly adaptable to the formation of color transparencies and accordingly, in a preferred form of this invention, the support is composed of a transparent material such as the transparent materials mentioned above.

Dyeable stratum 12 may comprise any of the materials heretofore employed in color transfer processes and may, for example, comprise a polymeric material such as polyvinyl alcohol or a mixture of polyvinyl alcohol and a polyvinyl pyridine, e.g., a poly-4-vinylpyridine. Such strata are described, for example, in U.S. Pat. No. 3,148,061. The dyeable stratum may also include other reagents performing specified desired functions, e.g., hardeners, diffusion agents or other reagents to reduce water-sensitivity, dye mordants, antifoggants, oxidizing agents, pH adjusters, or the like, all of which additional reagents are known in the art.

imagewise pattern of oxidized Stripping layer 14 is not necessary to the practice of this invention but is preferably employed to facilitate clear separation of the image-containing stratum 12 following processing,

as will be described with greater particularity hereinafter.

Stripping layers have heretofore been well known in diffusion transfer processes and per se comprise no part of this invention. As an example of such materials, mention may be made of cellulose acetate hydrogen phthalate.

The silver halide in layer 20 may be any of the heretofore employed light-sensitive silver halides, e.g., silver chloride, silver bromide or mixed halides such as silver bromoiodide, silver chlorobromide or silver chlorobromoiodide. The silver halide is preferably contained in a suitable polymeric matrix, the preferred being gelatino silver halide emulsions and more preferably those mixed halide gelatino silver halide emulsions known in the art as high speed emulsions.

Processing composition 22 comprises at least an aqueous medium containing an alkaline material such as sodium or potassium hydroxide and a silver halide developing agent of the type described in US. Pat. No. 3,443,939, which upon development will provide an oxidation product which can undergo a redox reaction with the color providing material in layer 16. Such developing agents include dihydroxybenzene developers such as the hydroquinones, aminophenol developers suchas metol, and diaminobenzene developers such as 2-amino-5-diethylamino-toluene. Any of these ingredients may be present initially in either or both of the respective elements, e.g., in layers 16 and/or 20, in which event the developing composition is obtained by applying the aqueous material to dissolve the component or components so contained. The processing composition may also contain various other reagents performing specific desired functions, e.g., stabilizers, antifoggants, viscous reagents and the like. In a preferred procedure, the processing composition is applied in a viscous form by including therein a viscous reagent such as hydroxyethyl cellulose, sodium carboxymethyl cellulose, etc. The processing composition may be contained initially in a frangible container or pod of the type heretofore well known in the art and disclosed, for example, in US. Pat. Nos. 2,543,l8 1, 2,647,056, as well as many others.

Upon applying the processing composition such as in the manner shown in the drawing, exposed and developable silver halide is developed and as a function of this development an developing agent is formed in terms of developed silver halide. This imagewise pattern of oxidized developing agent then contacts the color-providing material in layer 16 and this in turn causes the occurrence of the redox reaction referred to above and in US. Pat. No. 3,443,939,'thereby releasing the difi'usible color-providing moiety to provide an imagewise distribution of the same which is then transferred, by diffusion, to stratum 12 to impart thereto a negative color transfer image. Following development the dyeable stratum is separated from the stripping layer to reveal the desired image. As stated previously, in a preferred procedure contemplated by this invention, support is transparent and the resulting image is thus a negative color transparency.

As was mentioned previously the present invention is readi ly adaptable to the formation of radiographs or the like wherein the photosensitive element is exposed through the subject matter to be reproduced to penetrating ionizing radiation such as X-rays. In such procedures it is common practice to employ what is known in the art as an intensifier screen in order to reduce the amount of exposure or dosage of such radiation needed to provide the requisite exposure. A typical intensifier screen comprises a layer of a material which is fluorescent, e.g., contained phosphors which emit visible light upon activation by exposure to penetrating ionizing radiation. Thus a portion of this radiation contacts the silver halide to effect exposure thereof while another portion contacts the intensifier screen causing it to emit visible light or which further exposes or intensifies the exposure of the photosensitive layer to provide the desired developable image. As is well known in the art, the intensifier screen is placed in close optical proximity to the photosensitive layer during photo-exposure in order to provide a sharp developable image. The intensifier screen may be present as a separate element, i.e., contained on a separate support, or, in lieu thereof, it may be contained in a layer on the photosensitive element in accordance with procedures heretofore known in the art. The use of an intensifier screen and its precise structure and location during photoexposure per se comprise no part of this invention and the foregoing description is made merely for purposes of illustrating how one might prepare a radiograph in accordance with this invention.

The following example shows by way of illustration and not by way of limitation the practice of this invention.

EXAMPLE On a Mylar" (trademark of E. l. du Pont de Ncmours & Co. for a transparent film of polyethylenev terephthalate resin) support sheet was coated a dyeable stratum comprising a mixture of polyvinyl alcohol and poly-4-vinyl pyridine at a coverage of about 700 mgms./ft. sq. of surface area. Over this was applied a stripping layer by coating a solution of cellulose acetate hydrogen phthalate in acetone to provide a layer containing about 60 mgms. per sq. ft. of cellulose acetate hydrogen phthalate. An aqueous dispersion containing a dye of the formula:

I NH

was coated over the stripping layer to provide a layer containing about mgms. of the dye per sq. ft. of surface area, thereby providing an element as shown in the drawing. A high speed silver halide emulsion was exposed and then developed by applying between the thus exposed element and the element prepared above at a gap of 0.0016 inch a processing composition containing the following proportions of ingredients:

Water 2000.0 cc. Hydroxyethyl Cellulose I410 g. Sodium hydroxide 78.0 8. Metal 32.0 g. Zinc nitrate 10.0 g. Sodium bromide I00.0 g.

After an imbibition period of about 60 seconds the support carrying the dyeable stratum was separated to reveal a negative dye image of excellent resolution and quality.

Since the color-providing material has a shorter distance to diffuse from the layer containing the same to the dyeable stratum than in systems wherein the color-providing material is contained in the photosensitive element and must diffuse through this element and then across the "gap to the superposed dyeable stratum to form the desired color transfer image, the present invention has been found to provide transfer images of greater resolution or sharpness than those obtainable by the procedures wherein the color-providing material is contained in the photosensitive element. For the very same reason, the procedures of this invention make it possible to obtain transfer images of greater dye density. The present invention also provides certain other advantages over systems wherein the color providing material is contained in the photosensitive element. One such additional advantage is the fact that the present invention provides more versatility in the selection of the photosensitive materials, i.e., permits one to use any of the negatives including the various high speed negatives commercially available. In this regard it also permits one to use photosensitive elements for radiography wherein the intensifier screen is contained in the photosensitive element. Moreover since the color-providing material is not a pan of the photosensitive element, the coating of the same and any subsequent coatings may be prepared in the light, thereby facilitating commercial preparation of the element containing this material. Other advantages will be apparent from the foregoing description.

Since certain changes may be made in the above products and processes without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description and shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. An element for use in preparing photographic images in color comprising a support carrying on one side thereof a layer of a nondiffusible material containing a diffusible colorproviding moiety, which material is capable of forming by a redox reaction an oxidation product which can autoreact intramolecularly to effect ring-closure and to eliminate the color-providing moiety of said material for transfer; and a dyeable stratum disposed between said layer and said support.

2. An element as defined in claim 1 including a stripping layer disposed between said layer of nondiffusible material and said stratum.

3. An element as defined in claim 1 wherein said support is substantially transparent.

4. A photographic product including an element as defined in claim 1 and a photosensitive element comprising a support carrying a light-sensitive silver halide layer adapted for placement in superposition therewith.

5. A product as defined in claim 4 including a quantity of an aqueous alkaline processing composition adapted for spreading between said elements when in superposition.

6. An element as defined in claim 1 wherein said nondiffusible material is of the formula:

wherein:

each of A and A represents the atoms necessary to complete an aromatic ring;

D is a color-providing moiety;

Y is a substituent which completes an amide with and reduces the basic character of the 3-amino substituent bonded thereto, said Y substituent further being a divalent radical linking said D moiety to said 3-nitrogen atom;

X and X each is hydrogen, hydroxy, amino or the substituent R, provided that at least one of X and X must be hydroxy or amino;

R and R each represents an anchoring moiety rendering said compound nondiffusible;

R is hydrogen, alkyl or substituted alkyl; and

n and n each is l or 2, provided that when R is an alkyl radical or X or X is a secondary or tertiary amino comprising an anchoring moiety rendering said compound nondiffusible or when R, X and X together contribute an anchoring moiety, n and n may be I, but when said substituents alone or together do not contribute an anchoring moiety at least one of n and n must be 2.

7. An element for use in preparing photographic images in color comprising a support carrying on one side thereof, in order, a dyeable stratum, a stripping layer, and a layer containing a compound of the formula:

Roi-1) wherein:

each of R and R comprises an amide of at least 13 carbon atoms, said amide being bonded directly to a nuclear carbon atom of the shown benzene moiety or linked thereto through a phenylene or alkylene substituent; each ofn and n is l or 2, provided that at least one of said n and n is 2; and D is a monoazo, diazo or anthraquinone dye moiety. 8. An element as defined in claim 7 wherein said support is substantially transparent.

9. A photographic process comprising the steps of exposing a light-sensitive silver halide layer to form a developable image; developing said image by applying between the thus exposed layer and an element as defined in claim I an aqueous alkaline processing composition including a silver halide developing agent which when oxidized is capable of undergoing a redox reaction with said material; as a function of said development providing an imagewise distribution of oxidized developing agent in terms of developed areas of said silver halide layer; contacting said nondiffusible material with said imagewise distribution of oxidized developing agent whereby said material is selectively oxidized by a redox reaction with said oxidized silver halide developing agent to effect said ringclosure and to release said diffusible color-providing moiety in an imagewise pattern corresponding to said imagewise distribution of oxidized developing agent; and transferring said imagewise pattern of diffusible color-providing material, by diffusion, to said dyeable stratum whereby to impart thereto a color transfer image.

10. A process as defined in claim 9 wherein said color image is a negative transparency.

11. A process as defined in claim 9 wherein said nondiffusible material is a compound of the formula:

wherein:

each of A and A represents the atoms necessary to complete an aromatic ring; D is a color-providing moiety; Y is a substituent which completes an amide with and reduces the basic character of the 3-amino substituent bonded. thereto, said Y substituent further being a divalent radical linking said D moiety to said 3-nitrogen atom;

X and X each is hydrogen, hydroxy, amino or the sub stituent R, provided that at least one of X and X must be hydroxy or amino;

R is hydrogen, alkyl or substituted alkyl; and

n and n each is l or 2, provided that when R is an alkyl radical or X or X is a secondary or tertiary amino comprising an anchoring moiety rendering said compound nondiffusible or when R, X and X together contribute an anchoring moiety, n and n may be 1, but when said substituents alone or together do not contribute an anchoring moiety at least one or n and n must be 2.

12. A process as defined in claim 11 wherein said exposure to form said developable image is effected by penetrating ionizing radiation.

13. A process as defined in claim 12 wherein X-radiation radiation is X-radiation and said color image is a transparent radiograph.

14. A process as defined in claim 13 wherein an intensifier screen is positioned between said layer and said source of exposing radiation during said exposure.

15. A process as defined in claim 9 wherein the support for said element is substantially transparent and said material is a compound of the formula:

I OH

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3,617,275 Dated November 2, 1971 n fls) Stanley M. Bloom, Joel M. Peisach and Robert K.

Stephens It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 8, line 29 (appl. page 18, claim 7, line 14) "diazo" should be --disazo-.

Column 9, lines 19 and 20 (appl. page 20, claim 13,

should be line 2), "X-radiation radiation is X-radiation" -said radiation is Xradiation--.

Signed and sealed this 19th day of September 1972.

(SEAL) Attest:

ROBERT GU'I'TSCHALK EDWARD M.FLETCHER,JR. Attesting Officer Commissioner of Patents USCOMM-DC GOS'IG-PBQ

Claims

2. An element as defined in claim 1 including a stripping layer disposed between said layer of nondiffusible material and said stratum.
3. An element as defined in claim 1 wherein said support is substantially transparent.
4. A photographic product including an element as defined in claim 1 and a photosensitive element comprising a support carrying a light-sensitive silver halide layer adapted for placement in superposition therewith.
5. A product as defined in claim 4 including a quantity of an aqueous alkaline processing composition adapted for spreading between said elements when in superposition.
6. An element as defined in claim 1 wherein said nondiffusible material is of the formula:
7. An element for use in preparing photographic images in color comprising a support carrying on one side thereof, in order, a dyeable stratum, a stripping layer, and a layer containing a compound of the formula:
8. An element as defined in claim 7 wherein said support is substantially transparent.
9. A photographic process comprising the steps of exposing a light-sensitive silver halide layer to form a developable image; developing said image by applying between the thus exposed layer and an element as defined in claim 1 an aqueous alkaline processing composition including a silver halide developing agent which when oxidized is capable of undergoing a redox reaction with said material; as a function of said development providing an imagewise distribution of oxidized developing agent in terms of developed areas of said silver halide layer; contacting said nondiffusible material with said imagewise distribution of oxidized developing agent whereby said material is selectively oxidized by a redox reaction with said oxidized silver halide developing agent to effect said ring-closure and to release said diffusible color-providing moiety in an imagewise pattern corresponding to said imagewise distribution of oxidized developing agent; and transferring said imagewise pattern of diffusible color-providing material, by diffusion, to said dyeable stratum whereby to impart thereto a color transfer image.
10. A process as defined in claim 9 wherein said color image is a negative transparency.
11. A process as defined in claim 9 wherein said nondiffusible material is a compound of the formula:
12. A process as defined in claim 11 wherein said exposure to form said developable image is effected by penetrating ionizing radiation.
13. A process as defined in claim 12 wherein X-radiation radiation is X-radiation and said color image is a transparent radiograph.
14. A process as defined in claim 13 wherein an intensifier screen is positioned between said layer and said source of exposing radiation during said exposure.
15. A process as defined in claim 9 wherein the support for said element is substantially transparent and said material is a compound of the formula: