US3578447A - Dye developer color liffusion transfer processes and elements comprising alpha and gamma hydroxy and gamma amino substituted pyridines - Google Patents

Abstract

DYE-DEVELOPER DIFFUSION TRANSFER COLOR PROCESSES AND ELEMENTS AND COMPOSITIONS FOR EMPLOYMENT THEREIN, COMPRISING A COMPOUND SELECTED FROM ALPHA AND GAMMA HYDROXY AND GAMMA AMINO SUBSTITUTED PYDRIDINES ADAPTED TO REACT WITH THE OXIDATION PRODUCTS OF THE DYE DEVELOPERS TO PROVIDE DURING PROCESSING A PRODUCT WHICH IS LESS DIFFUSIBLE IN THE PROCESSING COMPOSITION THAN THE SAID DYE DEVELOPER OXIDATION PRODUCTS.

Description

DEVELOPER 00 May 11,1 DYE M. DIFFUS SIMON 3,578,447

TRANSFER PROCESSES AND ELEMENTS COMPRISING L HA AND GAMMA HYDROXY AND GAMMA AMINO SUBSTITUTED PYRIDINES Filed May 2 1969 )0 IZ /SUPPORT I3A\ r CYAN DYE DEvELoPER LAYER RED SITIVE SILVER HALIDE N LAYER l5* INTERLAYER H Is- -l -MAGENTA DYE DEVELOPER LAYER GREEN SENSI sILvER HALIDE EMuLsIoN LA Isl flNTERLAYER IQA\\\\\\\ YELLow DYE DEVELOPER LAYER 2o\, A BLUE SENSITIVE sILvER HALIDE EMuLsIoN LAYER 3I'-: ovERcoAT LAYER 27 -:I ':-'E- uEous ALKALINE PROCESSING I it: E MPOSITION 25% ///I/IMAGERECEIVING LAYER 24- -SPACER LAYER 22 25- ///I -NEUTRALIZING LAYER 2em sup om VENTO 8. SIM

ATTORNEYS United States Patent ()flice DYE DEVELOPER COLOR DIFFUSION TRANSFER PROCESSES AND ELEMENTS COMPRISING ALPHA AND GAMMA HYDROXY AND GAMMA AMINO SUBSTITUTED PYRIDINES Myron S. Simon, West Newton, Mass, assignor to Polaroid Corporation, Cambridge, Mass. Filed May 2, 1969, Ser. No. 821,191 Int. Cl. G03c 5/54, 7/00 U.S. Cl. %3 19 Claims ABSTRACT OF THE DISCLOSURE Dye-developer diffusion transfer color processes and elements and compositions for employment therein, comprising a compound selected from alpha and gamma hydroxy and gamma amino substituted pyridines adapted to react with the oxidation products of the dye developers to provide during processing a product which is less diffusible in the processing composition than the said dye developer oxidation products.

The present invention relates to photography and, more particularly, to processes for forming photographic diffusion transfer color images and products and compositions particularly adapted for employment in such processes.

Accordingly, it is a primary object of the present invention to provide novel photographic diffusion transfer color processes and novel products and compositions particularly adapted for employment in such processes; to provide novel photographic diffusion transfer color processes particularly adapted for the production of monochromatic and multichromatic images; to provide novel photographic products which comprise a photosensitive element which includes at least one photosensitive emulsion having associated therewith, as a color image-forming component, a dye of predetermined color which is a silver halide developing agent and a nucleophilic reagent adapted to react with the oxidation product of the dye to provide a dye adduct less diifusible during photographic processing than said oxidation product of said dye; to provide novel photographic products which include a photosensitive element which comprises at least one photosensitive silver halide emulsion having associated therewith a dye developer of predetermined color and a compound selected from a group consisting of alpha and gamma hydroxy and gamma amino substituted pyridines adapted to react with the oxidation product of the dye developer to provide a dye less diifusible during processing than the oxidation product of the dye; to provide novel photo graphic products, of the last-identified type, in combination with a photographic diffusion transfer image-receiving element including a layer dyeable by said dye; to provide novel photographic products comprising a film unit, of the last-identified type, in combination with a rupturable container adapted to retain fluid processing composition affixed one edge of one of said photosensitive and said image-receiving elements and adapted to distribute its fluid contents in contact with said photosensitive element: to provide novel photographic products, of the last identified type, wherein said rupturable container retains an aqueous alkaline processing solution in which said dye is diffusible; and to provide novel photographic products, of the last-identified type, wherein said rupturable container is positioned and extends transverse a leading edge of said film unit whereby to effect unidirectional discharge of said containers contents intermediate said photosensitive and said image-receiving element.

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

The invention accordingly comprises the processes 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 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 taken in connection with the accompanying drawing wherein:

The drawing is a diagrammatic enlarged cross-sectional vieW illustrating the association of elements during one stage of the performance of a diffusion transfer process for the production of a multicolor transfer image according to the present invention, the thickness of the various materials being exaggerated.

As disclosed in U.S. Pat. No. 2,983,606, a photosensitive element containing a dye developer and a silver halide emulsion is exposed and wetted by a liquid processing composition, for example, by immersion, coating, spraying, flowing, etc., in the dark, and the exposed photosensitive element is superposed prior to, during, or after Wetting, on a sheetlike support element which may be utilized as an image-receiving element. In a preferred embodiment, 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 of the latent image contained therein. The dye developer is immobilized or precipitated in exposed areas as a consequence of the development of the latent image. This immobilization is apparently, at least in part, due to a change in the solubility characteristics of the dye developer upon oxidation and especially as regards 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. In unexposed and partially exposed areas of the emulsion, the dye developer is unreacted and diifusible and thus provides an imagewise distribution of unoxidized dye developer dissolved in the liquid processing composition, as a function of the pointto-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, said transfer substantially excluding oxidized dye developer. The imagereceiving element receives a depthwise diffusion, from the developed emulsion, of unoxidized dye developer without appreciably disturbing the imagewise distribution thereof to provide the reversed or positive color image of the developed image. The desired positive image is revealed by stripping the image-receiving layer from the photosensitive element at the end of a suitable imbibition period.

The dye developers, as noted above, are compounds which contain, in the same molecule, both the chromophoric system of a dye and also a silver halide developing function. By a silver halide developing function is meant a grouping adapted to develop exposed silver halide. A preferred silver halide development function is a hydroquinonyl group. Other suitable developing functions include ortho-dihydroxyphenyl and ortho and para-amino substituted hydroxyphenyl groups. In general, the development function includes a benzenoid developing function, that is, an aromatic developing group which forms quinonoid or quinone substances when oxidized.

Multicolor images may be obtained using color image forming components such as, for example, the previously mentioned dye developers, in diffusion transfer processes Patented May 11, 1971 by several techniques. One such technique contemplates 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 US. Pat. No. 2,983,606. In such an embodiment, each of the minute photosensitive elements has associated therewith an appropriate dye developer in or behind the silver halide emulsion portion. In general, a suitable photosensitive screen, prepared in accordance with the disclosures of said patents, comprises minute red-sensitized emulsion elements, minute greensensitized emulsion elements and minute blue-sensitive 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 copending US. Patent No. 3,345,163, issued Oct. 3, 1967, wherein at least two selectively sensitized photosensitive strata are superposed on a single sup.- port and are processed, simultaneously and without separation, with a single, common image-receiving 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 bluesensitive silver halide emulsion stratum, said emulsions having associated therewith, respectively, for example, a cyan die 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 strata. Each set of silver halide emulsion and associated dye developer strata may be separated from other sets by suitable interlayers, for example, by a layer of gelatin or polyvinyl alcohol. In certain instances, it may be desirable to incorporate a yellow filter in front of the green-sensitive emulsion and such yellow filter may be incorporated in an interlayer. However, where desirable, a yellow dye developer of the appropriate spectral characteristics and present in a state capable of functioning as a yellow filter may be employed. In such instances, a separate yellow filter may be omitted.

An extensive compilation of specific dye developers particularly adapted for employment in photographic diffusion transfer processes is set forth in aforementioned US. Pat. No. 2,983,606, and in the various copending US. applications referred to in that patent, especially in the table of US. applications incorporated by reference into the patent as detailed in column 27. As examples of additional US. patents detailing specific dye developers for photographic transfer process use, mention may also be made of US. Pat. Nos. 2,983,605; 2,992,106; 3,047,386; 3,076,808; 3,076,820; 3,077,402; 3,126,280; 3,131,061; 3,134,762; 3,134,765; 3,135,604; 3,135,605; 3,135,606; 3,135,734; 3,141,772; 3,142,565; and the like.

As additional examples of synthetic, film-forming, permeable polymers particularly adapted to retain dispersed dye developer, mention may be made of nitrocarboxymethyl cellulose, as disclosed in US. Pat. No. 2,992,104;

, an acrylamidobenzene sulfo ester of a partial sulfobenzal of polyvinyl alcohol, as disclosed in U.S. Pat. No. 3,043,- 692; polymers of N-alkyl-afi-unsatumted carboxamides and copolymers of N-all yl-a,,8-carboxamides with N- hydroxyalkyl-nap-unsaturated carboxamides, as disclosed in US. Pat. No. 3,069,263; copolymers of vinyl-phthalimide and a,;8-unsaturated carboxylic acids, as disclosed in US. Pat. No. 3,061,428; copolymers of N-vinylpyrolidones, oc,[3-unsaturated carboxylic acids and terpolymers of N-vinylpyrrolidones, n p-unsaturated ,carboxylic acids and alkyl esters of cap-unsaturated carboxylic acids, as disclosed in US. Pat, No. 3,044,873; co-

4 polymers of N,N dialkyl-u,p-unsaturated carboxamides with cap-unsaturated carboxylic acids, the corresponding amides of such acids, and copolymers of N-aryland N-cycloalkyl-a,,B-unsaturated carboxamides with u,[S'-unsaturated carboxylic acids, as disclosed in US. Pat. No. 3,069,264; and the like.

In addition to conventional techniques for the direct dispersion of a particulate solid material in a polymeric, or colloidal, matrix such as ball-milling and the like tech niques, the preparation of the dye developer dispersion may also be obtained by dissolving the dye in an appropriate solvent, or mixture of solvents, and the resultant solution distributed in the polymeric binder, with optional subsequent removal of the solvent, or solvents, employed, as, for example, by vaporization where the selected solvent, or solvents, possesses a sufficiently low boiling point or Washing where the selected solvent, or solvents, possesses a sufficiently high differential solubility in the wash medium, for example, water, when measured against the solubility of the remaining composition components, and/ or obtained by dissolving both the polymeric binder and dye in a common solvent.

For further detailed treatment of solvent distribution systems of the types referred to above, and for an extensive compilation of the conventional solvents traditionally employed in the art to effect distribution of photographic color-providing materials in polymeric binders, specifically for the formation of component layers of photographic film units, reference may be made to US. Pats. Nos. 2,269,158; 2,322,027; 2,304,939; 2,304,940; 2,801,- 171; and the like.

US. Pat. No. 3,362,819, issued Jan. 9, 1968, discloses image-receiving elements, particularly adapted for employment in the preceding diffusion transfer processes, which comprise a support layer possessing on one surface thereof, in sequence, a polymeric acid layer, an inert timing or spacer layer, and an image-receiving layer adapted to provide a visible image upon transfer to said layer of diffusible dye image-forming substance.

As set forth in the last-mentioned patent, 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, particularly 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, nondiifusible from the acid polymer layer.

In order to prevent premature pH reduction during transfer processing, as evidenced, for example, by an undesired reduction in image density, the acid groups 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 alkali 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. These embodiments are illustrated, respectively, in the copending application, by (a) a mixture of cellulose acetate and cellulose acetate hydrogen phthalate and (b) a cellulose acetate hydrogen phthalate polymer having a much lower percentage of phthalyl groups than the first-mentioned cellulose acetate hydrogen phthalate.

It is also disclosed that 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.

In addition, as disclosed in the last-mentioned patent, an inert spacer layer, for example, comprising polyvinyl alcohol or gelatin may be employed to time control the pH reduction by the polymeric acid layer as a function of the rate at which alkali diffuses through the spacer layer.

As disclosed in the previously cited patents, the liquid processing composition referred to for effecting multicolor diffusion transfer processes comprises at least an aqueous solution of an alkaline material, for example, diethylamine, sodium hydroxide or sodium carbonate and the like, and preferably possessing a pH in excess of 12. Where this liquid processing composition is to be applied to the photosensitive emulsion stratum by being spread thereon, preferably in a relatively thin and uniform layer intermediate that stratum and a superposed image-receiving layer, it is disclosed to include a viscosity-increasing compound constituting a film-forming material of the type which, when the composition is spread and dried, forms a relatively firm and relatively stable film. The preferred film-forming materials disclosed comprise high molecular weight polymers such as polymeric, watersoluble ethers which are inert to an alkaline solution such as, for example, a hydroxyethyl cellulose or sodium carboxymethyl cellulose. Additionally, film-forming materials or thickening agents whose ability to increase viscosity is substantially unaffected if left in solution for a long period of time are also disclosed to be capable of utilization. As stated, the film-forming material is preferably contained in the processing composition in such suitable quantities as to impart to the composition a viscosity in excess of 100 cps. at a temperature of approximately 24 C. and preferably in the order of 100,000 cps. to 200,000 cps. at that temperature.

For the production of the photoresponsive gelatino silver halide emulsions employed to provide the film unit, the silver halide crystals may be prepared by reacting a Water-soluble silver salt, such as silver nitrate, with at least one water-soluble halide, such as ammonium, potassium or sodium bromide, preferably together with a corresponding iodide, in an aqueous solution of a peptizing agent such as a colloidal gelatin solution; digesting the dispersion at an elevated temperature, to provide increased crystal growth; washing the resultant dispersion to remove undesirable reaction products and residual water-soluble salts by chilling the dispersion, noodling the set dispersion, and washing the noodles with cold water, or, alternatively, employing any of the various floc systems, or procedures, adapted to effect removal of undesired components, for example, the procedures described in US. Pats. Nos. 2,614,928; 2,614,929; 2,728,662; and the like; after-ripening the dispersion at an elevated temperature in combination with the addition of gelatin and various adjuncts, for example, chemical sensitizing agents of US. Pats. Nos. 1,574,944; 1,623,499; 2,410,689; 2,597,856; 2,597,915; 2,487,850; 2,518,698; 2,521,926; and the like; all according to the traditional procedures of the art, as described in Neblette, C. 3., Photography, Its Materials and Processes, 6th ed., 1962.

Optical sensitization of the emulsions silver halide crystals may be accomplished by contact of the emulsion composition with an effective concentration of the selected optical sensitizing dyes dissolved in an appropriate dispersing solvent such as methanol, ethanol, acetone, water, and the like; all according to the traditional procedures of the art, as described in Hammer, F. M., The Cyanine Dyes and Related Compounds.

Additional optional additives, such as coating aids, hardeners, viscosity-increasing agents, stabilizers, preservatives, and the like, for example, those set forth hereinafter, also may be incorporated in the emulsion formulation, according to the conventional procedures known in the photographic emulsion manufacturing art.

The photoresponsive material of the photographic emulsion will, as previously described, preferably comprise a crystal of silver, for example, one or more of the silver halides such as silver chloride, silver iodide, silver bromide, or mixed silver halides such as silver chlorobromide or silver iodobromide, of varying halide ratios and varying silver concentrations.

The emulsions may include the various adjuncts, or addenda, according to the techniques disclosed in the art, such as speed-increasing compounds, stabilizers, hardening agents, coating aids, plasticizers, and the like.

As the binder for the respective emulsion strata, the aforementioned gelatin may be, in whole or in part, replaced with some other colloidal material such as albumin; casein; or zein; or resins such as a cellulose derivative, as described in U.S. Pats. Nos. 2,322,085 and 2,327,- 808; polyacrylamides, as described in US. Pat. N0. 2,541,474.

While transfer of oxidized dye developer according to the previously desirable diffusion transfer process is substantially excluded, it has been found that in 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 rendition, separation and/ or isolation, which in turn affects the color fidelity of the transfer image and, hence, is undesired. The greater the transfer of oxidized dye, the poorer the acuity 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, may not be sufficiently low in a selected processing composition to prevent at least minimal transfer of dye and even such minimal transfer may affect to a 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 developer by uuoxidized dye developer diffusion d'uring processing from the photosensitive element toward the image-receiving element. In fact, such reduc tion of oxidized dye in multilayer photosensitive elements statistically permits of greater transfer of undesired dye than that obtained by transfer of dye developer in its oxidized form.

To obviate the problem of undesired transfer of oxidized dye developer along with uuoxidized 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 diffusible, thereby precluding transfer.

For example, in aforementioned US. Pat. No. 2,983,- 606, 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, US. Pat. 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 uuoxidized 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 function, which, as was heretofore noted, is the preferred developer moiety.

It has now been quite unexpectedly discovered, however, that improved positive diffusion transfer monochromatic and multichromatic images may be provided by a photographic diffusion transfer color process which comprises selectively exposing a photographic film unit which includes a photosensitive element comprising a photosensitive silver halide emulsion having associated therewith a dye developer; contacting the photosensitive silver halide emulsion with an aqueous alkaline processing composition having an alkali concentration at which the dye developer is ditfusible to a contiguous image-receiving layer and a nucleophilic reagent adapted to react with the oxidation product of the dye developer to provide a dye developer adduct substantially nondiffusible in aqueous alkaline processing composition to a contiguous imagereceiving layer; effecting thereby development of the selectively exposed silver halide emulsion; forming thereby an imagewise distribution of diifusible dye developer, as a function of the point-to-point degree of emulsion exposure; and transferring, by diffusion, at least a portion of the image-wise distribution of diffusible dye developer to an image-receiving element which includes a polymeric layer dyeable by the dye developer to provide thereto a dye image in terms of the imagewise distribution.

Specifically, it has been unexpectedly discovered that the aforementioned diffusion transfer process employing an aqueous alkaline processing composition in which the dye developer is dilfusible may be improved by being conducted in the presence of a nucleophilic reagent capable of reacting with the oxidation product of the dye developer as a function of and proportional to development, for example, a reactive nucleophilic reagent comprising a phenolic hydroxyl or amino group adapted to react with oxidized dye developer, to provide a dye developer adduct which is less diifusible to a contiguous image-receiving layer than oxidized dye developer and is thus substantially nondiffusible to such layer. By this mechanism there is thus provided an image wise distribution of mobile, diffusible dye in terms of unexposed areas of the photosensitive emulsion for transfer by diffusion to a contiguous dye image-receptive element for production of an improved positive dye developer transfer image.

Particularly suitable nucleophilic reagents comprise alpha and gamma hydroxy and gamma amino pyridines which during diffusion transfer processing provide a pyridine dye developer, nucleophilic adduct by addition to oxidized dye developer, resultant from development of exposed silver halide, proportional to and as a function of exposure, which adduct is less ditfusfble than oxidized dye developer at alkali concentrations at which reduced dye developer is diffusible to the contiguous image-receiving element.

According to the present invention, undesired or unwanted transfer of the oxidation product of a dye developer, formed as a function of the development of an exposed photosensitive silver halide emulsion and/ or reduction of the oxidation product and subsequent transfer thereof, may be obviated by utilizing in conjunction with such dye developer, a nucleophilic reagent of the aforementioned type which is adapted to react with dye developer oxidation product to provide a molecule which is substantially less mobile, and preferably is effectively insoluble and nondilfusible, in the transfer processing composition employed. As illustrative examples of particularly preferred reagents contemplated for employment in the practice of the present invention, mention may be made of Various compounds particularly preferred for employment in the practice of the present invention may be prepared by synthetic procedures well known in the art, for example synthetic procedures of the types set forth in The Chemistry of Heterocyclic Compounds, vol. 14, Pyridine and Its Derivatives, Part 3, Chapter XII, Pyridinols and Pyridines, Interscience Publishers, New York, N.Y., and the literature articles incorporated therein by reference and in particular, Bardhan, J. C., J. Chem. Soc., 1929, p. 2223 and Bassu, 1., Indian Chem. Soc. 7, 815 (1930).

Among the plurality o synthetic procedures available for the production of the preferred compounds, a particularly preferred procedure adopted for the expedious preparation of a multiplicity of such compounds in high yield may be represented synthetic process equation:

CNCH2CONH2 RCOCl+R COCHa ROOCHZCOR R @CEN R OH R- the CEN groups of which may be readily removed, at the election of the operator, by alkaline hydrolysis and concurrent decarboxylation of the selected compound synthesized.

Although the reagents of the present invention are herein referred to and described employing the stated pyridine structural designation, it will be recognized that the subject reagents may exist in any one or more of the various isomeric (tautomeric) forms which are capable, theoretically at least, of changing into each other, and may be employed in any form active for the purpose of the invention, such as, for example, the corresponding pyridine forms.

In a preferred embodiment of the present invention, the photosensitive element is employed which is specifi- CEN cally 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 is diffusible, in alkali at the selected processing concentration. The preferred photoinsensitive 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 elements initial alkali processing concentration to a lower alkali concentration; and a dimensionally stable transparent 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 diffusible in the reduced form at the alkali concentration employed for processing possessing, subsequent to processing, a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion.

In the preferred embodiment, each of the emulsion strate, and its associated dye, is separated from the remaining emulsion strata, and their associated dye, by separate alkaline solution permeable polymeric interlayers and the dyeable polymeric layer is separated from the polymeric acid layer by an alkaline solution permeable polymeric spacer layer having decreasing permeability to alkaline solution with increasing temperature.

In such preferred embodiment of the invention, 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, preferably gelatin, 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. It will be specifically recognized that the relative dimensions recited above may be appropriately modified, in accordance with the desires of the operator, with respect to the specific product to be ultimately prepared.

In general, the optimum concentration of the specific pyridine to be employed should be determined empirically for each specific photographic color transfer system employed. However, in general the preferred concentration falls within the range of about 0.5 to 150 g. per 100 cc. of processing composition solvent, i.e., water, employed to effect processing of the film unit, depending upon the specific characteristics of the individual dye developer or developers and pyridine or pyridines selected. Although concentrations in excess of the range may be employed, increasing the concentration beyond the stated limits generally provides no additional beneficial results in most instances. Conversely, concentrations below that of the designated range, merely decrease the effect of the additive below the effective level generally sought, but do not prevent operation of the invention. Where desired, however, substantial quantities of the additive may be employed without introducing seriously deleterious photographic effects.

In the preferred embodiment of the present inventions film unit for the production of a multicolor transfer image, 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.

The reagents of the present invention may be present initially in the processing composition, the photo-sensitive element and/or the image-receiving element as a monomeric and/or polymeric reagent. The reagent may be thus disposed, in the preferred multicolor film unit, associated with any or all of the emulsion layers constituting the film unit, in a layer intermediate respective emulsion layers of the unit and/ or dye developer containing layers associated with the emulsions, and may be employed in conjunction with the onium compounds identified above and/ or other such compounds as are known in the art for increasing dye image fidelity.

Reference is now made to the drawing wherein there is illustrated a preferred film unit of the present invention.

As illustrated in the drawing, 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 1S; 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. Each of emulsion layers 14, 17 and 20 most preferably contain a dispersion of the nucleophilic reagent adapted to react with the oxidation product of its respective, associated dye developer, as a function of and proportional to development of the emulsion layer, to provide a dye developer adduct less iffusible in a selected processing composition medium than oxidized dye developer.

As shown in the drawing, 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.

In the performance of a diffusion transfer multicolor process employing film unit 10, the unit is exposed to radiation, actinic to photosensitive laminate 11.

Subsequent to exposure, 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 an alkali concentration at which the cyan, magenta and yellow dye deveopers are dilfusible, 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 14, 17 and 20, are mobilized, as a function of the development of their respective associated silver halide emulsions, preferably substantially as a result of their conversion from the diffusible reduced form to their relatively nondifiusible adduct form, thereby providing imagewise distribution of mobile, soluble and ditfusible 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 1 ll yellow dye developer transfers, by diffusion, to aqueous alkaline solution permeable polymeric layer 23 to provide a multicolor dye transfer image to that layer. Subsequent to substantial transfer image formation, 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 whereby alkaline solution 27 decreases in alkali concentration, as a function of neutralization, to an alkali concentration providing enhanced stability to the multicolor dye transfer image.

Subsequent to substantial transfer image formation, print-receiving element 22 may be manually dissociated from the remainder of the film unit, for example, by stripping.

The present invention will be illustrated in greater detail in conjunction with the following specific examples which set out representative photographic products and processes which, however, are also intended to be illustrative and not of limiting efiect.

An image-receiving element of the type set forth in the drawing may be prepared by coating a cellulose nitrate subcoated opaque baryta paper with the partial butyl ester of poly-ethylene/maleic anhydride copolymer prepared by refluxing, for 14 hours, 300 grams of DX-840-31 resin [tradename of Monsanto Chemical Co., St. Louis, Mo., for high viscosity poly-(ethylene/maleic anhydride) 140 grams of n-butyl alcohol and 1 cc. of 85% phosphoric acid to provide a polymeric acid layer approximately 0.3 mil thick. The external surface of the acid layer may be coated with a 4% solution of polyvinyl alcohol in watermethanol-isopropanol to provide a polymeric spacer layer approximately 0.15 mil thick. The external surface of the spacer layer may then be coated with a 2:1 mixture, by weight, of polyvinyl alcohol and poly-4-vinyl pyridine, at a coverage of approximately 600 mgs./ft.. to provide a polymeric image-receiving layer approximately 0.40 mil thick.

A multicolor, multilayer photosensitive element of the type set forth in the drawing may be prepared in a manner similar to that disclosed in the aforementioned US. Pat. No. 3,345,163 and detailed hereinbefore. In general, the photosensitive elements may comprise an opaque support carrying a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum and a bluesensitive silver halide emulsion stratum, each containing a nucleophilic adjunct. In turn, the emulsions may have 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 gelatin interlayer may be positioned between the yellow dye developer layer and the green-sensitive emulsion stratum, and also between the magenta dye developer layer and the red-sensitive emulsion stratum. The particular nucleophilic reagent selected may comprise The particular dye developers employed in the photosensitive elements may comprise 1,4-bis-(a-methyl-{i-hydroquinonylethylamino -5,8-dihydroxyanthraquinone (a cyan dye developer); 2- p- [2,5 -dihydroxyphenethyl] -phenylazo)-4-isopropoxy-l-naphthol (a magenta dye developer); and 1-phenyl-3-n-hexylcarbamyl 4 (p-[hydroquinonylethyl]-phenylaZo--pyrazolone (a yellow dye developer). The last-mentioned yellow and magenta dye developers are disclosed in US. Pat. No. 3,134,764 and the cyan dye developer is disclosed in U.S. Pat. No. 3,135,606.

12 The photosensitive element may then be exposed in a Polaroid Land Camera and processed by spreading an aqueous liquid processing composition comprising:

Watercc.

Hydroxyethyl cellulose (high viscosity) [commercially available from Hercules Powder Co., Wilmington, Del., under the trade name Natrosol 250]3.8 g.

Potassium hydroxide1l.2 g.

Benzotriazole3.5 g.

between image-receiving element and the exposed multicolor element in superposed relationship. After an imbibition period of about 60 seconds, the image-receiving element may be separated from the remainder of the film unit to reveal the requisite positive dye image formation.

Examination of resultant dye transfer prints will reveal image formation to be substantially completed and to exhibit the required color balance, hues, saturation and isolation, within the stated period.

For the explicit purpose of providing definitive comparative data evaluating the unexpected and advantageous results obtained by means of the practice of the present invention, as compared with processes disclosed in the prior art, two separate photosensitive elements were prepared as detailed below.

The first photosensitive element was prepared by coating a gelatin subcoat carrying opaque cellulose triacetate film base, in succession, with a layer comprising l-phenyl- 3-n-hexyl-carbamyl 4 (p-[hydroquinonylethyl] -phenylaZo)-5-pyrazolone (a yellow dye developer) in gelatin at a coverage of 54 mgs./ft. dye and 68 mgs./ft. gelatin; a layer comprising a greenand blue-sensitive gelatino silver halide emulsion containing an ortho-hydroxy pyridine adjunct of the specific formula CEN 1'1 HggCn \N OH and coated at a coverage of 193 mgs./ft. silver, 183 mgs./ft. gelatin and 147 mgs./ft. pyridine; and a gelatin layer coated at a coverage of 30 mgs./ft.

A second, optimized control photosensitive element was prepared as above by coating the gelatin subcoated opaque cellulose triacetate film base with a layer comprising 54 mgs./ft. of the yellow dye developer identified above; a greenand blue-sensitive gelatino silver halide emulsion comprising 176 mgs./ft. silver and 172 mgs./ft. gelatin; and a gelatin layer coated at a coverage of 30 mgs./ft.

Each of the photosensitive elements were then selectively exposed to incident blue light and processed by spreading of the aqueous liquid processing composition set forth above between the thus exposed photosensitive element and an image-receiving element of the structure detailed above in superposed relationship. After a period of about 60 seconds the respective image-receiving elements were separated from the remainder of the film units.

The test procedure was then repeated employing a processing composition which additionally contained 1.9 grams of the quaternary salt compound benzylpyridini-um bromide and again repeated employing a processing composition which additionally contained 2.0 grams of the active quaternary salt compound benzyl-u-picolinium bromide.

The dye transfer images thus obtained detail the quantum of undesired dye transfer from areas of the photosensitive element corresponding to photoexposed areas of the emulsion layer with which the dye was associated.

The number of density units and the percent improvement based upon the difference of dye density units between the structure of the present invention, the control structure and the active and inactive quaternary compound containing structures of the prior art is detailed hereinafter in the following table wherein the D f represents yellow dye density, respectively, of the transfer image, in areas of the image-receiving element directly corresponding to areas of the photosensitive element exposed to blue light.

3,039,869, issued June 19, 1962. As examples of suitable combinations of auxiliary developing agents, mention may be made of l-phenyl-3-pyrazolidone in combination with p-benzylaminophenol and 1-phenyl-3-pyrazolidone in com- TABLE Density Density Density improveimproveimprovement vs. ment vs. ment vs. control inactive active (decrease quaternary quaternary Percent Percent Percent in dye system system improveimproveimprovedensity (decrease (decrease ment vs. ment vs. ment vs. units) in dye in dye control inactive active density density quaternary quaternary Dmin, units) units) system system Test 0. 25 0.36 0. 35 0. 51 59 58 67 Control Inactive quaternary system Test and inactive quaternary system. Active quaternary system Test and active quaternary system 1 Equal to test results within degree of experimental error.

2 Competition with active quaternary compound for oxidized dye destroyed test compound efiect. From the foregoing tabular date, it will be directly obbination with 2,5-bis-ethylenimino-hydroquinone. Such served that the compounds of the present invention materially reduce transfer of oxidized yellow dye developer when directly compared with a control and prior art inactive and active onium systems; thus directly increasing the information fidelity of the photographic diffusion transfer system employing such.

Although in each of the above examples a single reagent of the present invention was employed, it will be apparent that the simultaneous and requential employment of two or more of such compounds is intended to be within the scope of this invention and that, as previously noted, one or more of such agents may optionally be initially disposed in the photosensitive element, the image-receiving element and/or the processing composition at the election of the operator. In addition, the compounds of the present invention, unlike the onium compounds of the prior art, fail to exhibit the problems of density active, when initially disposed in the photosensitive element, as is inherent in the employment of active onium compounds of the prior art.

The alkali concentration of the alkaline processing solution initially employed must be a concentration at which the dye developers selected are diffusible in their reduced form. Although it has been found that the specific alkali concentration to be employed may be readily determined emperically for any dye developer or group or dye developers, most particularly desirable dye developers are diffusible in alkali concentrations providing a pH above 9 and the system can be readily balanced accordingly for such dye developers. In addition, although as previously noted, the processing composition, in the preferred embodiment, will include the stated film-forming viscosityincreasing agent, or agents, to facilitate spreading of the composition and to provide maintenance of the spread composition as a structurally stable layer of the laminate, subsequent to distribution, it is not necessary that such agent be employed as a component of the composition. In the latter instance, however, it will be preferred that the concentration of solvent, that is, water, etc., comprising the composition be the minimum amount necessary to conduct the desired transfer process, in order not to adversely affect the structural integrity of the laminate and that the layers forming the laminate can readily accommodate and dissipate the solvent throughout during processing and drying without effecting undesirable dimensional changes in the layers forming the laminate.

It will be noted that the liquid processing composition employed as previously mentioned may contain an auxiliary or accelerating developing agent, such as p-methylaminophenol, 2,4-diaminophenol, p-benzylaminophenol, hydroquinone, toluhydroquinone, phenylhydroquinone, 4- methylphenylhydroquinone, 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.

auxiliary developing agents may be employed in the liquid processing composition or they may be initially incorporated, at least in part, in any one or more of the silver halide emulsion strata, the strata containing the dye developers, the interlayers, the overcoat layed, the image-receiving layer, or in any other auxiliary layer, or layers, 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 energy-transfer 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.

It will be apparent that the relative proportions of the agents of the diffusion transfer processing composition may be altered to suit the requirements of the operator. Thus, it is within the scope of this invention to modify the herein described developing compositions by the substitution of preservatives, alkalies, etc., other than those specifically mentioned, provided that the pH of the composition is initially at the first pH required. When desirable, it is also contemplated to include, in the developing composition, components such as restrainers, accelerators, etc. Similarly, the concentration of various components may be varied over a wide range and when desirable adaptable components may be disposed in the photosensitive element, prior to exposure, in a separate permeable layer of the photosensitive element and/ or in the photo sensitive emulsion.

The dimensionally stable layers referred to may comprise any of various types of conventional opaque and transparent rigid or flexible materials, for example, glass, paper, metal, and polymeric films of both synthetic types and those derived from naturally occuring products. Suitable materials include alkaline solution impermeable materials such as polymethacrylic acid, methyl and ethyl esters; vinyl chloride polymers; polyvinyl aeetal; 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. It will be recognized that one or more of the designated layers may not be required where the remaining layers of the laminate are such as to provide the functions of these layers in the absence of same, for example, where the remaining layers of the laminate provide the requisite dimensional stability and radiation filtering properties.

In all examples of this specification, percentages of components are given by weight unless Otherwise indicated.

The present invention also includes the employment of a black dye developer and the use of a mixture of dye developers adapted to provide a black and white transfer image, for example, the employment of dye developers of the three subtractive colors in an appropriate mixture in which the quantities of the dye developers are proportioned such that the colors combine to provide black.

Where in the specification, 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 substantially reversed as to its conformation with respect to the silver image formed in the photosensitive emulsion layers.

In addition to the described essential layers, it will be recognized that the film unit may also contain one or more subcoats or layers, which, in turn, may contain one or more additives such as plasticizers, intermediate essential layers for the purpose, for example, of improving adhesion, and that any one or more of the described layers may comprise a composite of two or more strata of the same, or different, components and which may be contiguous, or separated from, each other, for example, two or more neutralizing layers or the like, one of which may be disposed intermediate the cyan dye image-forming component retaining layer and the dimensionally stable support layer.

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

What is claimed is:

1. A photographic film unit which comprises a photosensitive element containing photosensitive silver halide having associated therewith a dye which is a silver halide developing agent and a compound selected from the group consisting of alpha and gamma hydroxy and gamma amino substituted pyridines adapted to react with the oxidation product of said dye to provide a dye-pyridine adduct less diffusible in aqueous alkaline solution than said dye.

2. A photographic film unit as defined in claim 1 wherein said dye includes a phenyl group containing at least two groups selected from the group consisting of hydroxy and amino groups, at least one of said groups substituted in one of ortho and para positions with respect to one other of said groups.

3. A photographic film unit as defined in claim 2 wherein said dye contains at least one para dihydroxyphenol group.

4. A photographic film unit as defined in claim 3 wherein said compound is 5. A photographic film unit as defined in claim 1 including an image-receiving element containing a polymeric layer dyeable by said dye afiixed at least one edge of said phtotosensitive element and adapted to be superposed on photosensitive element.

6. A photographic film unit as defined in claim 5 including a rupturable container adapted to retain a fluid processing composition afiixed one edge of one of said photosensitive and said image-receiving elements and to distribute its fluid contents intermediate said elements in superposed relationship.

7. A photographic film unit as defined in claim 6 wherein said compound is initially disposed in said fluid processing composition.

8. A photographic film unit as defined in claim 5 wherein said image-receiving element comprises a support carrying said dyeable polymeric layer and retaining intermediate said support and said dyeable layer a permeable polymeric acid layer.

9. A photographic film unit as defined in claim 1 wherein said photosensitive element comprises at least two selectively sensitized silver halide emulsion layers each having a dye, which dye is a silver halide developing agent of predetermined color associated therewith.

10. A photographic film unit as defined in claim 9 wherein each of said selectively sensitized silver halide emulsion layers possesses predominant spectral sensitivity to separate regions of the visible spectrum and the dye associated with each of said silved halide emulsion layers possesses subsequent to processing a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion layer.

11. A photographic film unit as defined in claim 10 wherein said photosensitive element contains, as essential layers, a red-sensitive silver halide emulsion layer, having cyan dye associated therewith, a green-sensitive silver halide emulsion layer having magneta dye associated therewith, and a blue-sensitive silver halide emulsion layer having yellow dye associated therewith, each of said cyan, magenta and yellow dyes being silver halide developing agents.

12. A process of forming transfer images in color which comprises, in combination, the steps of:

(a) exposing a photographic film unit which includes,

in combination, a photosensitive element containing a photosensitive silver halide emulsion having associated therewith a dye, which dye is a silver halide developing agent;

(b) contacting said photosensitive silver halide emulsion with an aqueous alkaline processing composition having an alkali concentration at which said dye is diflusible and a compound selected from a group consisting of an alpha and gamma hydroxy and gamma amino pyridine adapted to react with the oxidation product of said dye to provide a dye-pyridine adduct substantially nondiffusible to a superposed image-receiving element which includes a polymeric layer dyeable by said dye;

(c) effecting thereby development of said silver halide emulsion and oxidation of said dye as a function of the point-to-point degree of emulsion exposure;

((1) forming thereby an imagewise distribution of diffusible dye; and

(e) transferring, by diifusion, at least a portion of said imagewise distribution of diffusible dye to said image-receiving element to provide thereto a dye image in terms of said imagewise distribution.

13. A process as defined in claim 12 wherein said photosensitive element comprises in contiguous relationship at least two selectively sensitized silver halide emulsion layers each having a dye, which dye is a silver halide developing agent, of predetermined color associated therewith, each of said dyes nondiffusible in said processing composition at said alkali concentration.

14. A process as defined in claim 13 wherein each of said selectively sensitized silver halide emulsion layers possess predominant spectral sensitivity to separate regions of the visible spectrum and the dye associated with each of said emulsion layers possesses subsequent to processing a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion layer.

15. A process as defined in claim 14 wherein each of said silver halide emulsion layers and its associated dye is separated from the next adjacent layer and its associated dye by an alkaline solution permeable polymeric interlayer.

16. A process as defined in claim 15 wherein said photosensitive element contains, as essential layers, in sequence, a support layer; an alkaline solution permeable polymeric layer containing cyan dye; a red-sensitive silver halide emulsion layer; an alkaline solution permeable polymeric layer containing a magenta dye; a greensensitive silver halide emulsion layer; an alkaline solution permeable polymeric layer containing a yellow dye; a blue-sensitive silver halide emulsion layer, each of said cyan, magenta and yellow dyes being a silver halide developing agent and wherein said image-receiving element contains, as essential layers, in sequence, an alkaline solution permeable polymeric layer dyeable by said dyes; an alkaline solution permeable polymeric acid layer; and a support layer.

17. A photographic process as defined in claim 12 wherein said dye includes a phenyl group containing at least two groups selected from the group consisting of 15 18 19. A process as defined in claim 18 wherein said compound is References Cited UNITED STATES PATENTS 3,502,468 3/1970 Rogers 96-29 J. TRAVIS BROWN, Primary Examiner A. T. SURO PICO, Assistant Examiner U.S. Cl. X.R.

Images