US3502468A - Color diffusion transfer process with a methine or methylene coupler - Google Patents

Description

United States Patent 3,502,468 COLOR DIFFUSION TRANSFER PROCESS WITH A METHINE OR METHYLENE COUPLER Howard G. Rogers, Weston, Mass., assignor to Polaroid Corporation, Cambridge, Mass., a corporation of Delaware No Drawing. Filed May 12, 1965, Ser. No. 455,302 Int. 'Cl. G03c 5/54, 7/30 US. Cl. 96-29 37 Claims ABSTRACT OF THE DISCLOSURE Photographic diffusion transfer systems using a dihydroxyphenyl silver halide developing agent, including systems employing dye developers containing a dihydroxyphenyl developing function to obtain color transfer images, wherein unwanted transfer of oxidized developing agent formed as a function of development is obviated by contacting said oxidized developing agent with a coupler, e.g., a compound containing a methine or methylene group substituted by at least one activating group having no formal charge, to form a more bulky molecule which is substantially less mobile in the processing composition.

This invention relates to photography and, more particularly, to novel photographic products and processes for preparing color images utilizing dye developers.

A primary object of this invention is to provide novel photographic products and processes for preparing transfer images.

Another object is to provide novel products and processes for improving the color separation of color transfer images.

Yet another object is to provide novel products and processes for preparing color transfer images possessing whiter highlight areas.

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

The invention accordingly comprises the process involving the several steps with respect to each of the others, and the product possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of 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.

US. Patent No. 2,983,606 issued to Howard G. Rogers relates to diffusion transfer processes wherein dye developers are utilized to develop an exposed photosensitive element and to form a color transfer image on a superposed image-receiving layer. Dye developers are dyes which contain, in the same molecule, a silver halide developing function and a chromophoric system of a dye. A particularly useful class of dye developers are those con taining a hydroquinonyl developing function.

In processes of this type, an exposed photosensitive element containing at least one silver halide emulsion is wetted by a liquid processing composition, for example, by immersing, coating, spraying, flowing, etc., in the dark, and the exposed photosensitive element may be superposed prior to, during, or after wetting, on a sheet-like image-receiving element containing a dyeable stratum for receiving a dye transfer image. In a preferred embodiment, the photosensitive element contains a layer of dye developer associated with each of one or more silver halide emulsions (depending upon whether monochromatic or multicolor images are contemplated) and the liquid processing composition is applied to the photosensitive element in a uniform layer as the photosensitive element is brought into superposed relationship with the image receiving element. As is disclosed in the aforementioned patent, the processing composition may be confined in a rupturable container which is capable, upon rupturing, of spreading its contents in a substantially uniform layer between the superposed elements. Where monochromatic images are desired, the dye developer may also be present initially in the liquid processing composition. The processing composition permeates the emulsion to initiate development and as a function thereof, the dye developer is oxidized and rendered less mobile and less diffusible, at least in the processing composition which is alkaline. In unexposed and partially exposed areas of the emulsion, the dye developer is unreacted land diffusible, thus providing, as a function of the point-to-point degree of development of the silver halide emulsion, an imagewise distribution of unoxidized dye developer diffusible in the liquid processing composition. At least part of this imagewise distribution of unoxidized dye developer is transferred, by imbibition, to the superposed imagereceiving element to form thereon a positive dye image.

While transfer of oxidized dye developer is substantially excluded, it has been found that in many instances at least some, albeit minimal amounts, of oxidized dye developer does in fact transfer to the image-receiving element. This transfer of oxidized dye developer results in less than perfect color separation or isolation, which in turn affects the color fidelity of the transfer image and, hence, is unwanted. The greater the transfer of oxidized dye, the poorer the color separation and, in turn, the poorer the quality of the transfer image. The undesired transfer of oxidized dye developer is believed to be due primarily to the fact that the mobility of the oxidation product, i.e., the oxidized dye developer, is not sufficiently low in the processing composition to prevent at least minimal transfer of dye and even such minimal transfer may affect to some degree the quality of the dye transfer image. In multilayer photosensitive elements, the unwanted transfer of dye from exposed areas may also be due, at least in part, to reduction of oxidized dye developers by unoxidized dye developer migrating from the photosensitive element toward the image-receiving element. In fact, the reduction of oxidized dye in multilayer photosensitive elements permits of greater transfer of unwanted dye than that obtained by transfer of dye developer in its oxidized form.

To obviate the problem of unwanted transfer of oxidized dye developer along with unoxidized dye developer (or reduction of oxidized dye developer and subsequent transfer thereof), it has heretofore been suggested to employ certain additives which will react with the oxidized dye developer to render it even less mobile and less diifusible, thereby precluding transfer.

For example, in the aforementioned patent it is suggested that, when employing a dye developer having a free amino group as a part of its developing function, e.g., an aminophenol or diaminobenzene developing function, a dye or coupler capable of coupling with the oxidized developer to provide a less mobile reaction product, may also be employed.

In addition to the above-mentioned use of dyes and couplers which will couple with the oxidation product of an amino-containing developing function of the foregoing description, U.S. Patent No. 3,173,786 issued to Milton Green and Howard G. Rogers discloses the concept of employing an onium compound which not only will increase the transfer of the desired unoxidized dye developer to increase the density of the dye image, but will also inhibit transfer of oxidized dye developer to improve the highlights. The latter concept is particularly useful since it may be employed in conjunction with dye developers containing a hydroquinonyl developing func- 3 tion, which, as was heretofore noted, is the preferred developer moiety.

The present invention relates to an alternate method of precluding transfer of oxidized dye developer, which provides cerain advantages over the use of onium compounds or onium compounds alone.

According to the present invention, unwanted transfer of the oxidation product of a dye developer containing a dihydroxyphenyl developing function formed as a function of development of an exposed photosensitive silver halide emulsion with the said dye developer, and/or reduction of the oxidation product and subsequent transfer thereof may be obviated by utilizing in conjunction therewith a compound capable of coupling with the oxidation product to form a more bulky molecule which is substantially less mobile and preferably is effectively insoluble and immobile in the processing composition. The dihydroxyphenyl developing functions to which this invention is directed are those containing at least one free or unsubstituted position ortho to one of the said hydroxy radicals, e.g., hydroquinonyl and substituted hydroquinonyl radicals containing at least one free position.

These coupling compounds may be defined as compounds containing a methine H or methylene (CH group substituted by at least one activating group having no formal charge, preferably a strongly activating group such as a cyano or carbonyl group, and most preferably substituted by (bonded to) two activating groups. In those compounds containing a methine group, the third substituent bonded thereto may be an activating group, an insolubilizing group or a group which inhibits or minimizes color in the reaction product.

These compounds may also be described as having an activated hydrogen atom on a carbon atom alpha to at least one activating group having no formal charge, preferably a strongly activating group, and most preferably alpha to two activating groups.

In any event, the designated carbon atom may be part of an open chain structure or it may be a member of a ring system. The compound containing the same may be a monomer or a polymer and is preferably colorless or substantially colorless.

Compounds of this nature are generally known in the photographic art as useful couplers with color developing agents, e.g., the p-phenylene diamine series, to form a dye, (see, for example, Mees, The Theory of the Photographic Process, revised edition, 1954, pp. 594-597) although, as far as is known, it has never heretofore been contemplated that such compounds may be employed in the manner herein contemplated, namely to couple with the oxidation product of a dihydroxyphenyl silver halide developing function of the foregoing description or a compound containing the same, e.g., a dye developer.

The coupling reaction contemplated by the Present invention is also distinguishable chemically from the aforementioned known coupling with amine-containing developers. In the latter case coupling occurs on the nitrogen atom whereas in the present case, coupling is believed to occur on a ring carbon atom ortho to a quinone linkage formed as a function of oxidation of the dihydroxyphenyl developing moiety.

As examples of compounds of the foregoing description which are useful in the practice of this invention, mention may be made of the following:

CEN

GEN

C O O C2H5 'H C H; H OlN Tautomer k/ CO O C2H NEG-CHz-CEN CHCEN (Q7 i CH2CEN (53) O O OH OH OH Lil CH2-C0CH (56) GEN CH=COOCH m d m...

They may be employed in conjunction with photosensitive elements containing a single emulsion layer, i.e., a monochrome photosensitive element, or they may be employed in conjunction with a multilayer photosensitive element, i.e., one employed in the preparation of multicolor images. As is disclosed in the aforementioned patent of Howard G. Rogers, such a photosensitive element may for example contain a blue-sensitive emulsion and associated yellow dye developer; a green-sensitive emulsion and associated magenta dye developer; and a red-sensitive emulsion and associated cyan dye developer. The dye developers may be present in the respective associated emulsion layers or they may be present in a layer therebeneath. Suitable spacer layers may be provided, if desired, in which event the coupler may be incorporated into one or more spacer layers, or, as mentioned above, it may be incorporated in a single layer or overcoat over the outermost emulsion layer.

It will be appreciated that, in multilayer photosensitive elements such as described above, a coupler compound may be associated with any or all of the emulsion layers, e.g., in a layer between the emulsion layer and dye developer-containing layer associated therewith. It will also be appreciated that the coupler may be used in conjunction with the onium compounds heretofore mentioned or other compounds for increasing dye density and/or color separation.

The ability to employ the compounds of this invention in the photosensitive element affords a distinct advantage over the use of onium compounds for the same purpose, since it has been found that many onium compounds cannot be employed in the photosensitive emulsion in large amounts without causing desensitization of the emulsion and other such problems. Employing the compound in the photosensitive element, as distinguished from having it contained initially elsewhere, e.g., in the processing composition, makes it possible to obtain more eflicient usage thereof, since the coupler is in immediate proximity with the dye developer so as to react with and thus immobilize oxidized dye developer before it has had opportunity to migrate from the photosensitive element.

In addition to the foregoing advantage, the present invention provides a further significant practical advantage over the use of onium compounds.

in photographic processes utilizing dye developers in the preparation of a color transfer image, it is often desirable to employ, for example, in the processing composition, one or more auxiliary or accelerating silver halide developing agents such as 4'-rnethylphenylhydroquinone. Although such compounds are substantially colorless, at least in their unoxidized form, it has been found that when oxidized they may cause some staining or greying of the highlight areas in the transfer print. While the exact reason for this greying or staining of the highlight areas is not clear, it is believed that this discoloration is due to the formation of a colored reaction product from the onium compound heretofore employed and the oxidized auxiliary developer. In any event, it has been found that the coupling compounds of this invention do not so react with auxiliary developers such as 4-methylphenylhydroquinone to form a colored reaction product which causes discoloration of the highlights, and in fact may provide whiter highlight areas than are obtainable with or without additives such as the onium compounds.

The present invention also makes it possible to employ a wider range of dye developers since it is possible for the dye developers to contain solubilizing groups, for example on the dye moiety, and still be immobilized in terms of exposed areas by the coupling reaction.

The reaction product formed by coupling may be of substantially the same color as the dihydroxyphenyl-containing compound or the reaction product may possess materially different spectral absorption characteristics.

In the following series of illustrative examples, comparison is made between the color separation or isolation obtained by exposing a multilayer photosensitive element (negative) and developing the thus-exposed negative with a control aqueous processing composition containing only 10 EXAMPLE 4 Example 1 was repeated employing similar materials and processing conditions, except that the processing composition also contained 1,29 g. of 2-cyano-1-tetralone,

alkali and a viscous reagent and that obtained by extautomer (Formula posing and developing a similar negative with a like processing composition containing the designated coupler EXAMPLE 5 Example 1 was repeated employing similar materials 1 Instances negatlve 15 l h blue and processing conditions, except that the processing sensitive, green-sensltlve and redsensltive s lver iodobrocomposition also contained of ethylacetamido bide emulsion layers have positioned behind them, recyanoacetate (Formula spectively, a. yellow dye developer, a magenta dye developer and a cyan dye developer. A gelatin interlayer is EXAMPLE 6 Positioned between the Yellow y developed 631 and Example 1 was repeated employing similar materials the gee-Sensitive emulsion, and between the magenta y 15 and processng conditions, except that the processing comdevelopel' and the Tedfiehsitive emulsioh- Multilayfil' hegaposition also contained 1.33 g. of 3-phenyl-2,4-pentadione, tives of this type are disclosed, for example, in "FIG. 9 tautomel- (F l 6), of the aforementioned US. Patent No. 2,983,606. The dye developer layers are prepared by dissolving each dye EXAMPLE 7 developer in a water-imiscible solvent and dispersing the The dye transfer images obtained in Examples 1-6 resulting solution in gelatin. The particular yellow, rnawere analyzed to determine color isolation, i.e., the genta and cyan dye developers employed were: l-phenylamount of unwanted dye transfer from areas correspond- 3 N-n-hexylcarbamyl-4-[p-(2,5'-dihydroxyphenethyl)- ing to exposed areas of the emulsion layer with which the phenylazo]-5-pyrazolone (yellow); 2-[p-(2',5-dihydroxydye was associated. To determine isolation, the neutral, phenethyl) phenylazo] 4 isopropoxy-1-napth0l(ma-, the red, the green and the blue columns on the respective genta); and 1,4 bis [a methyl-,B-hydroquinonyl-ethyldye transfer images were read on a MacBeth densitomeamino]-5,S-dihydroxy-anthraquinone(cyan). ter. The integral densities of red, green and blue light The image-receiving element was one containing a received were then transposed to dye densities by use of layer of a polymeric acid separated from the image-rean analytical computer. The cyan density of the neutral ceiving layer (dyeable stratum) by an inert layer, such column was compared to the cyan density of the red as described and claimed in application Ser. No. 234,864, column and the difference was recorded as isolation efl'ifiled Nov. 1, 1962, in the name of Edwin H. Land, now ciency. The same procedure was performed for the ma- U.S. Patent No. 3,362,819. genta dye density in the neutral column versus the magenta dye density of the green column, and the yellow dye EXAMPLE 1 density of the neutral column versus the yellow dye The negative described above was Subjected to ah density of the blue column. The number of dye density y yp exposure consisting of a fed, a green and a units and the percent of improvement in color isolation blue exposure, Which combined gave a neutral (1011111111 based upon the difference in dye density units between the and singly gave green and blue colhmhs- A p control and the processing composition containing the tablet was used to alternate light in one-stop increments 40 coupler were d t i d to form various densities in the neutral colmn from These lt are set forth in the following table, white to black and in the red, green and blue columns wherein C, M and Y represent cyan, magenta and from color to black. The duration of exposure was oneyellow, respectively, and the numerical data represent one-thousandth of asecond. Following exposure, the the number of dye density units.

TABLE 1 Example 2 Example 3 Example 4 Example 5 Example 6 o M Y o M Y 0 M Y C M Y c M Y Test (Example No.) .02 .10 .14 .03 .24 .20 .01 .16 .20 .01 .13 .23 0 .14 .21 Control (Example 1) O .34 .27 0 .34 .27 0 .34 .27 0 .34 .27 0 .34 .27 Density improvement (Decrease in dye density units) None .18 .13 None .10 .01 None .18 .07 None .21 .04 None .20 .06 Percent improvement None 53 .48 None 32 4 None 53 39 None 62 15 None 59 29 negative was developed by spreading between the thus- EXAMPLE 8 pq negatlve. and the .albove'mentioned Examples 1-6 were repeated in each instance adding celvmguelement superposltion therewllh at a gap of 0.6 g. of 4-methylphenylhydroquinone to the processing 00044 the followmg processmg compostlon: composition. Color isolation of the dye transfer images Water-100 cc. obtained thereby was determined in the manner described Potassium hydroxide-11.2 g. in Example 7. The improvement in color isolation was Hydroxyethyl cellulose (high viscosity)3.9 g. 60 generally comparable, in some instances being less and After an imbibition period of about sixty seconds, the m some Instances f if i greatelr' image-receiving element was separated to provide the From the foregoing 1 ustratwe examp It W111 be observed that the coupler compounds materially reduced control dye transfer image.

, transfer of oxldlzed magenta and yellow dye developer, EXAMPLE 2 thereby materially improving color separation and thus Example 1 was repeated employing Similar materials the fidelity of reproduction of the original subject matter. and processing conditions, except that the processing Although number of cyan dye t uhlts composition also contained 1.18 g. of 2,2-dicyanoethylgeneraliy lPcreased, by one or F umts, thls mmute benzene (Formula crease 1s visually nconsequential and the overall effect was a substantial improvement in color separation. EXAMPLE 3 It will be noted that in each of the above examples, a Example 1 was repeated employing similar materials Single coup e compound Was added to the Processing d processing di i except h t th processing composition. It is within the scope of this invention to composition also contained 1.32 g. of benzyl cyanoacetic employ a mixture of two or more such compounds, and, acid (Formula 2). in fact, such a mixture has been found in some instances to provide a still greater improvement in color separa tion. For example, a processing solution containing a mixture of 0.41 g. of benzyl cyanoacetic acid (Formula 2), and 0.32 g. of Z-cyano-l-tetralone, tautomer (Formula 3), 11.2 g. of potassium hydroxide and 3.9 g. of hydroxyethyl cellulose in 100 cc. of water, gave better color separation than when either compound alone was added to the processing composition, e.g., as described in Examples 3 and 4. The fact that the total amount of coupler in the mixture was less than the amount of either coupler singly in Example 3 or 4 indicates that the greater color separation obtained by admixture of the two may be synergistic rather than being merely synergetic.

As was mentioned previously, it is possible to employ the coupler compounds of this invention in the photosensitive element without the problems of desensitization, etc., inherent in the use of onium compounds.

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

EXAMPLE 9 A multilayer photosensitive element similar to that employed in the foregoing examples was overcoated with a 2% solution of cellulose acetate hydrogen phthalate in acetone/methanol (20:80) at a rate of 15 ft./n1inute to provide a control negative. A similar photosensitive element was overcoated at the same speed with a solution prepared by dissolving 0.57 g. of ethyl-a-benzyl acetoacetate (Formula 45) in 14.5 cc. of a 2% solution of cellulose acetate hydrogen phthalate in acetone/methanol (20:80). The solution concentration was 3.8%. Each of these negatives was exposed and processed in the manner described in Example 1. After separation from the negative, the resulting positive dye transfer images were washed with 2% boric acid to remove any processing reagent which may have adhered. Analysis in the manner described in Example 8, provided the following resultsi C M Y Negative with coupler 02 07 06 Control negative 81 18 Density improvement (decrease dye density units 0 .24 12 Percent improvement 0 78 67 EXAMPLE EXAMPLE 1 l The dye densities (stain) of the highlight regions of the transfer images prepared in Example 9 were determined. The results were as follows:

C M Y Negative with coupler 02 06 04 Control negative 01 16 16 Density improvement (decrease density units) 0 10 12 Percent improvement 0 68 70 EXAMPLE 12 The dye densities (stain) of the highlights of the 12 transfer images obtained in Example 10 were determined. The results were as follows:

From Examples 11 and 12, it will be observed that the negative with coupler also provided cleaner or whiter highlights.

EXAMPLE 13 Substitution of the other mentioned illustrative compounds, i.e., Formula 5, and 764 in the procedures set forth in Examples 1 and 2 demonstrated the ability of all of these compounds to couple with oxidized dye developer to improve color separation materially.

While the above examples have been given for purposes of illustrating the invention, it will be appreciated that the invention is not restricted to the particular com bination of ingredients or proportions thereof, nor is the invention restricted to the recited structures. For example, improved color separation over that of a control transfer image has also been obtained by incorporating the coupler in a layer in the image-receiving element.

Likewise, improved color separation has been obtained by employing a coupler in combination with an onium compound. Hence, this combination of ingredients function together to improve the quality of the image.

While the illustrative examples all pertain to multicolor images, it will be apparent that the invention is also useful in the preparation of monochromatic images.

Although reference has been made throughout the foregoing specification to color photography, it will be noted that the present invention is also useful in black-andwhite photographic products and processes, e.g., in those directed to the preparation of positive silver transfer images. In such processes, staining of the highlight areas sometimes occurs due to the presence on the receiving layer of oxidized silver halide developing agent, e.g., 4- methylphenylhydroquinone, or a reaction product thereof. It will therefore be apparent that the ability of the couplers to react with such developers in accordance with the practice of this invention to form a less mobile and/or colorless reaction product, will be useful in black-andwhite transfer processes as well.

Since certain changes maybe made in the above process and product without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description shall be interpreted as i lustrative and not in a limiting sense.

What is claimed is:

1. In a photographic process for fonning a color transfer image wherein an exposed photosensitive element having at least one light-sensitive silver halide emulsion containing a developable image is contacted wtih an aqueous alkaline dye developer composition to develop exposed areas of said emulsion, said dye developer being a dye containing a dihydroxyphenyl silver halide developing function, said dye developer being oxidized in developed areas of said emulsion as a function of development, an imagewise distribution of unoxidized dye developer is formed in undeveloped areas, and said imagewise distribution is at least in part transferred, by diffusion, to a superposed image-receiving element to form a positive dye transfer image thereon; the step which comprises contacting said oxidized dye developer with a coupler to form a reaction product which is substantially less mobile in an aqueous alkaline medium than said oxidized dye developer, said coupler being a compound containing a member of the group consisting of methine and methylene radicals substituted by at least one activating group having no formal charge.

13 2. A process as defined in claim 1 wherein said radical is substituted by at least one strongly activating group.

3. A process as defined in claim 2 wherein said strongly activating group is selected from the group conslsting of cyano and carbonyl radicals.

v 4. A process as defined in claim 2 wherein said radical is substituted by two activating groups.

5. A process a defined in claim 1 wherein said processing composition contains at least one of said couplers.

6. Aprocess as defined in claim 1 wherein said processing composition contains a mixture of said couplers.

7. Aprocess as defined in claim 1 wherein at least one coupler is disposed initially in said photosensitive element.

8. A process as defined in claim 1 wherein a mixture of said couplers is disposed initially in said photosensitive element.

9. A process as defined in claim 1 wherein at least one coupler-is disposed initially in said image-receiving element.

10. A process as defined in claim 1 wherein said coupler issubstantially colorless.

11. A process as defined in claim 1 wherein said reaction product possesses substantially the same spectral absorption characteristics as said dye developer.

12. In a photographic process comprising the steps of exposing a photosensitive element containing a plurality of light-sensitive silver halide emulsions, each of said emulsions having associated therewith a dye developer, each of said dye developers containing a dihydroxyphenyl silver halide developing function, whereby to form a developa'ble image; developing said exposed photosensitive element by contacting it with an aqueous processing composition, oxidizing said dye developer as a function of development to form an imagewise distribution of OX1- dized dye developer in developed areas of each of said associated emulsions while forming in undeveloped areas of each of said emulsions an imagewise distribution of said associated dye developer in unoxidized and dilfusible form, and transferring, by diffusion, at least a portion of each said imagewise distribution of unoxidized dye developer' to a superposed image-receiving layer to form a dye transfer image thereon; the step which comprises contacting at least one of said imagewise distributions of x1- dized dye developers with a coupler to form a reaction product which is substantially less mobile than said 0x1- dized dye developer in said processing composition, said coupler being a compound containing a member of the group consisting of methine and methylene radicals substituted by at least one activating group having no formal charge.

131 A process as defined in claim 12 wherein said radicalfis substituted by two activating groups.

14. A process as defined in claim 13 wherein at least one coupler is present in at least one layer in said photosensitive element.

15. A process as defined in claim 13 wherein at least one coupler is in a layer over the outermost of said emulsions.

16. A process as defined in claim 15 wherein a mixture of said couplers is disposed initially in said photosensitive element.

17. A process as defined in claim 12 wherein at least one coupler is disposed initially in said processing composition.

18. A process as defined in claim 17 wherein said processing composition contains a mixture of said coupiers.

19. A process as defined in claim 12'wherein said processing composition contains an accelerating silver halide developing agent.

20. A process as defined in claim 19 wherein said accelerating developing agent is 4'-methylphenylhydroquinone.

21. A process as defined in claim 12 wherein the dihydroxyphenyl developing function of at least one of said dye developers comprises a hydroquinonyl radical.

22. A process as defined in claim 12 wherein said coupler is substantially colorless. Y

23. In a photographic process for preparing transfer images wherein a photosensitive element containing a light-sensitive silver halide emulsion is exposed to form a developable image, said exposed element is contacted with an aqueous processing composition containing at least one dihydroxyphenyl silver halide developing agent to develop said image and to form an imagewise distribution of image-forming constituents which is transferred, by diffusion, to a superposed image-receiving layer to form a transfer image thereon, said developing agent being oxidized in developed areas as a function of said development, the improvement which comprises reacting said oxidized developing agent with a compound containing a member of the group consisting of methine and methylene radicals substituted by at least one activating group having no formal charge to form a reaction product substantially less mobile than said oxidized developing agent.

24. A process as defined in claim 23 wherein said developing agent is 4'-methylphenylhydroquinone.

25. A process as defined in claim 24 wherein said transfer image is a positive silver image.

26. In a photographic process wherein an exposed photosensitive element having at least one light-sensitive silver halide emulsion containing a developable image is developed by contacting it with an aqueous processing composition containing a dihydroxyphenyl silver halide developing agent, said developing agent being oxidized in developed areas of said emulsion as a function of development; the improvement which comprises contacting said oxidized developing agent with a coupler to form a reaction product which is substantially less mobile than said oxidized developing agent, said coupler being a compound containing a member of the group consisting of methine and methylene radicals substituted by at least one activating group having no formal charge.

27. A process as defined in claim 26 wherein said developing agent is a dye developer.

28. A photographic product comprising a support containing on the same side thereof a dye developer, said dye developer being a dye containing a dihydroxyphenyl silver halide developing radical having a free position ortho to at least one of said hydroxy substituents; a light-sensitive silver halide emulsion; and a compound containing a member of the group consisting of methine and methylene radicals substituted by at least one activating group having no formal charge.

29. A photographic product as defined in claim 28 wherein said dye developer, emulsion and compound are disposed in separate layers.

30. A photographic product comprising a support having thereon a red-sensitive silver halide emulsion layer, a green-sensitive silver halide emulsion layer, and a bluesensitive silver halide emulsion layer, each of said emulsion layers having associated therewith, respectively, a cyan dye developer, a magenta dye developer, and a yellow dye developer, each of said dye developers being disposed in an alkali-permeable layer behind its associated emulsion layer, each of said dye developers being a dye containing a dihydroxyphenyl silver halide developing radical having a free position ortho to at least one of said hydroxy substituents, said product further including at least one compound containing a member of the group consisting of methine and methylene radicals substituted by at least one activating group having no formal charge, said compound being capable of reacting with oxidized dihydroxyphenyl silver halide developing agent to form a reaction product which is substantially less mobile than said oxidized developing agent.

31. A photographic product as defined in claim 36 wherein said compound is in a layer positioned over the outermost of said emulsion layers.

32. A photographic product as defined in claim 31 wherein said last-named layer contains a mixture of said compounds.

33. A sheet-like element comprising a support having thereon an image-receiving layer including at least one compound containing a member of the group consisting of methine and methylene radicals substituted by at least one activating group having no formal charge.

34. An element as defined in claim 33 wherein Said compound is disposed in said image-receiving layer.

35. A photographic product comprising: (a) a photosensitive element comprising a support having thereon at least one silver halide emulsion, each of said silver halide emulsion having associated therewith a dye developer, each said dye developer being a dye containing a dihydroxyphenyl silver halide developing radical having a free position ortho to at least one of said hydroxy substituents; (b) an image-receiving element comprising a support carrying an image-receiving layer; and (c) a rupturable container releasably holding an aqueous alkaline processing composition, said photosensitive element and said image-receiving element being adapted to be placed in superposition with said rupturable container positioned therebetween, said rupturable container being adapted to release the processing composition confined therein upon rupturing of said container, in a substantially uniform layer between said superposed elements; one of said photosensitive element, image-receiving element and processing composition further including at least one compound containing a member of the group consisting of methine and methylene radicals substituted by at least one activating group having no formal charge, said compound being capable of reacting with oxidized dihydroxyphenyl silver halide developing agent to form a reaction product which is substantially less mobile than said oxidized developing agent 36. A photographic product as defined in claim 35 wherein said compound is disposed in said processing composition.

37. A photographic product as defined in claim 36 wherein said processing composition contains a mixture of said compounds.

References Cited UNITED STATES PATENTS 5/1961 Rogers.

OTHER REFERENCES GEORGE F. LESMES, Primary Examiner I. P. BRAMMER, Assistant Examiner US. Cl. X.R. 963