US3345163A

US3345163A - Photographic diffusion transfer color processes

Info

Publication number: US3345163A
Application number: US565135A
Authority: US
Inventors: Edwin H Land; Howard G Rogers
Original assignee: Polaroid Corp
Current assignee: Polaroid Corp
Priority date: 1956-02-13
Filing date: 1956-02-13
Publication date: 1967-10-03
Anticipated expiration: 1984-10-03
Also published as: SE335061B; US3236893A; GB858673A; FR1185402A; NL214522A; NL218146A; US3019107A; NL105917C; GB853479A; FR1185401A; GB853478A; GB853482A; CH361194A; DE1047620B; NL293714A; BE554935A; CH444344A; FR1196814A; DE1287717B; GB853480A

Description

Oct. 3, 1967 LAND ET AL 3,345,163

PHOTOGRAPHIC DI FFUSION TRANSFER COLOR PROCESSES Filed Feb. 13, 1956 2 Sheets-Sheet 1 Suppor+ 'yer of Cyan Dye Developer ed Sensll'ive Emulsion ela'lin Layer l3 [2' QC'f'/ /i Ti;.(/ reen Sensilive Emulsion I4 '4 U a o u 5 u r'l'icles of Magenla Dye Developer 14b l l v l l l l elal'in. Layer Conl'ainlng Yellow Fill r l5 l6{ 22 O o Blue Sensil'ive Emulsion r'l'icles of Yellow Dye Developer Image Receiving Elemenl' 20 X /Suppor+ 2| {Parficles of Orange Red 2|: Sensil'lve Emulsion 2| 9 G 6 E] Q g l Parl'icles of Cyan Dye Developer 23 Q E f l 6 Barrier Layer 22 1) A Am i i :7 ZQ Q A'- {Par'l'lcles of Blue Green A a) G) A a) m 9 4 Sensi'l'ive Emulsion 2 2 Parl'icles of Orange Dye Developer 34-$+ra+a of Green Sensi'l'ive Emulsion 33-Slral'a of Magenla Dye Developer Suppor'l Sl'ra-l'a of Cyan Dye Developer Sl'ral'a of Red Sensi'l'ive Emulsion arrier Layer Layer of Yellow Dye Developer Blue Sensil'ive Emulsion ATTORNEYS Oct. 3, 1967 HLAND ETAL 3,345,163

PHOTOGRAPHIC DIFFUSION TRANSFER COLOR PROCESSES :Filed Feb. 13, 1956 2 SheetS Sheet 2 Suppor'l' Layer of Cyan Dye Developer L I l Red Sensilive Emulsion 43 l a Barrier Layer I 44 l I, Loyer of Magenla Dye Developer- 45, Green Sensirive Emulsion 46 Barrier Layer 4? Layer of Yellow Dye Developer 48 lue Sensi'l'ive Emulsion- FIG. 4

Supporl' 5O Layer of Cyan Dye {Red Sensi+ive Emulsion Conl'aining 5 Non-Diffusing Tanning Developer Layer of Magenl'a Coupling Dye 54 Green Sensilive Emulsion C'onl'aining Non- Difl using Color Developer 56 Yellow Fill'er' Loyer 57 lue Sensil'ive Emulsion 58 Image Receiving Elemenl' Liquid Processing Composil'ion Conl'aini-ng Yellow Dye Developer FlG. 5

[Liquid Processing Composil'ion Con'l'aining Insoluble SaH' Forming Reagenl' 5| I Blue-Sensil'ive Emulsion 62 Yellow Dye Developer 63 Spa'l'ial Barrier Layer 64 vGreen-Sensi'l'ive Emulsion Magen'l'a Dye Developer 67 Spal'ial Barrier Layer 53 l l Red -Sensi+ive Emulsion 69 Cyan Dye Developer 70 Layer Con'laining SolubIe-Sal+Forming Reagenl pp INV NTORS I 2 BYM E OAVTTORNEYS United States Patent PHOTOGRAPHIC DIFFUSION TRANSFER COLOR PROCESSES Edwin H. Land, Cambridge, and Howard G. Rogers, Weston, Mass., assignors to Polaroid Corporation, Cambridge, Mass., a corporation of Delaware Filed Feb. 13, 1956, Ser. No. 565,135 7 Claims. (Cl. 96-3) This invention relates to the art of photography, and more particularly to novel processes for the formation of color images and to photographic products for use with such processes.

It has been proposed in US. Patent No. 2,647,049, issued to Edwin H. Land on July 28, 1953, to form multicolor pictures by a diffusion transfer-reversal process wherein a plurality of positive dye images are formed in separate image-receiving layers, which layers are thereafter superposed in registered relationship to provide a multicolor picture. In such a process, a plurality of separate photosensitive layers containing latent color record images are processed to develop said latent images and to form a plurality of positive color records in separate image-receiving layers.

The present invention is concerned with improvements in the formation of color images by diffusion transferreversal processes and especially processes for the formation of such images using an integral, multilayer, negative photosensitive element.

It is a primary object of this invention to provide novel difiusion transfer-reversal processes wherein a positive multicolor image may be obtained on a single imagereceiving layer using an integral multilayer photosensitive element, and to provide suitable photographic products for performing such processes.

Another object of this invention is to provide difiusion transfer-reversal processes wherein diffusion of the colorproviding substances associated with at least one emulsion layer of an integral multilayer photosensitive element to an image-receiving layer is controlled in such a way as to be deferred until at least substantial development of the latent color record contained in said emulsion layer has occurred.

It is a further object of this invention to provide improved processes for the formation of the positive multicolor photographs wherein accurate registration of separately formed color records may be readily obtained on a single image-receiving layer.

These and further objects of the 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 products 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 disclosure taken in connection with the accompanying drawings wherein:

FIGURE 1 is a diagrammatic cross-sectional view of one embodiment of a multilayer photosensitive element suitable for use in the process of this invention in association with an image-receiving element and a rupturable container holding a liquid processing composition;

FIG. 2 is a diagrammatic cross-sectional view of another embodiment of a multilayer photosensitive element;

FIG. 3 is a dagrammatic cross-sectional view of a further embodiment of a multilayer photosensitive element wherein one photosensitive layer comprises a photosensitive screen;

3,345,163 Patented Oct. 3, 1967 FIG. 4 is a diagrammatic cross-sectional view of a furthe; embodiment of a multilayer photosensitive element; an

FIG. 5 is a diagrammatic cross-sectional view of still another embodiment of a multilayer photosensitive element in association With an image-receiving element and a rupturable container similar to that of FIGURE 1.

In diffusion transfer-reversal processes of the type herein contemplated, an exposed photosensitive silver halide emulsion layer containing a latent color record image is processed by a liquid processing composition to obtain an imagewise distribution of diffusible color-providing substances. The imagewise distribution of diffusible colorproviding substances results from the immobilization or trapping of color-providing substances in exposed areas, in situ with the developed silver, as a result of development of the latent image. A positive image may be obtained by the transfer of such difiusible, nonimmobilized color-providing substances, by imbibition, from the developed photosensitive layer to a superposed image-receiving layer. The desired positive image is revealed by stripping the image-receiving layer from the developed photosensitive layer after a suitable imbibition period.

Diffusion transfer-reversal color processes described in the prior art have found it necessary to employ separate, independent negative layers to record each portion of the spectrum, process them separately and form the respective positive color images on separate, independent imagereceiving layers which must thereafter be superposed in registered relationship to obtain the desired multicolor image. Alternatively, the multicolor positive image might be formed by successively bringing each separate negative layer, individually processed, into superposed registered relationship with an image-receiving element.

It has now been discovered that a positive multicolor image may be formed on a common image-receiving element by the use of a negative element comprising a plurality of superposed emulsion layers, said negative element being processed as an integral unit and superposed on said common image-receiving element without separation of the several emulsion layers. The novel, integral multilayer photosensitive elements contemplated offer great advantages over the prior art in producing superior multicolor images as well as increased simplicity in manufacture and use.

In its preferred aspect, this invention comprises the discovery that superior multicolor positive images may be imparted to a single image-receiving layer from an integr al multilayer photosensitive element comprising a plurality of superposed photosensitive emulsion layers Which are processed as a unit in conjunction with a common image-receiving element, by suitably controlling the diffusibility, i.e., availability for transfer, of at least the colora providing substances associatedwith the inner emulsion layer or layers and which have not been immobilized as a result of development of said emulsion, whereby such nonimmobilized color-providing substances are not rendered diffusible until after at least substantial development of the latent image in the next outermost emulsion layer. Such control of the diffusion of color-providing substances may be effected by restricting their outward diffusibility, i.e., deferring or retarding their ability to diffuse to the image-receiving layer, until after the desired development has occurred, whereby participation of such nonimmobilized color-prodiving substances in the development of other emulsion layers may be avoided. Thus, by deferred diffusibility it is intended to cover situations where nonimmobilized color-providing substances associated with an inner emulsion are rendered diifusible after at least substantial development of an outer emulsion has occurred but simultaneously with the development of said inner emulsion, or where development of both said inner and outer emulsion layers has been substantially completed.

The expression color-providing substances as used herein is intended to include all types of reagents which may be utilized to produce a color image, and such reagents may initially possess the desired color or may undergo a reaction after transfer to give the desired color. In a preferred embodiment, the color-providing substances are dye developers, that is, complete dyes which have a silver halide developing function, as disclosed in the copending application of Howard G. Rogers, Ser. No. 415,- 073, filed Mar 9, 1954, now abandoned and replaced by a continuation-in-part thereof, Ser. No. 748,421, filed July 14, 1958 now US. Patent No. 2,983,606 issued May 9, 1961. The use of color formers or couplers which react with the oxidation product of color developers to produce a dye is also contemplated within the term color-providing substances. The use of complete dyes per se as colorforming substances is also within the scope of this invention. The nature of these and other color-providing substances will be referred to in more detail hereinafter.

The expression integral multilayer photosensitive element as used herein is intended to include photosensitive elements comprising at least two separate, superposed layers of photosensitive material, each layer being selectively sensitized to an appropriate portion of the spectrum, at least the inner layer or layers having associated therewith appropriate color-providing substances. The integral multilayer photosensitive element is intended to be processed without separation of the layers. The imagewise distribution of diffusible color-forming substances present in each layer as a result of the development of latent images therein is transferred to a single, common image-receiving element to provide the desired multicolor image. As will be demonstrated hereinafter, the term layer is intended to include a stratum comprising a mixture of two differently sensitized photosensitive emulsions, as well as a stratum comprising a photosensitive screen comprising two sets of differently sensitized, minute photosensitive elements.

As noted hereinabove, multicolor positive images are formed in accordance with this invention by suitable control of the diffusibility or availability for diffusion of colorproviding substances associated with at least the inner photosensitive layer or layers to other photosensitive layers of an integral multilayer photosensitive element or to the image-receiving layer. This control of the availability of color-providing substances may be described as deferred mobility, deferred diffusibility or retarded mobility. Such control of the nonimmobilized color-providing substances is necessary to insure that they do not participate in the development of the latent color record image in a photosensitive layer or stratum other than that with which they are associated. This is particularly essential where the nonimmobilized color-providing substance is capable of developing exposed silver halide. Color-providing substances whose ability to diffuse has not been impaired by the development of the latent image are termed diffusible or nonimmobilized color-providing substances. Those color-providing substances, which are no longer free to diffuse as a result of development of exposed silver halide, are termed immobile or immobilized colorproviding substances. It is to be understood that, prior to development, all of the color-providing substances present are considered mobile in that they are potentially diffusible. Various mechanisms may be utilized to create the desired deferred diffusibility of the color-providing substances, and a particular integral multilayer photosensitive elements may utilize the same or several different mechanisms for creating the desired deferred diffusibility in the several layers.

While it is essential that the color-providing substances in the inner layer or layers have a deferred diffusibility, it is contemplated that the color-providing substances associated with the outermost photosensitive layer may transfer or diffuse to the image-receiving element at any stage in the processing thereof. It is necessary, however, to insure that such color-providing substances do not diffuse inwardly. Thus it will be seen that the color-providing substances to be associated with the outermost layer may, if desired, be introduced as ingredients of the liquid processing composition.

Although it is desirable that the deferred diffusibility of the nonimmobilized color-providing substances associated wtih an inner layer should be such that said substances do not become available for diffusion until development of at least the latent color record image in the next outer emulsion layer is substantially complete, it is only necessary that this deferred diffusibility be of such duration as to restrict diffusion until after at least substantial development of said latent image has occurred.

By the expression substantial development, as used in this specification and in the claims, is meant the minimum development of the latent image, i.e., negative density, adapted to produce substantially clean highlights of a color record in the transferred, positive image and to be substantially unaffected by diffusion into said emulsion of an unoxidized developing agent originally associated with a differently sensitized emulsion.

In general, it may be stated that the desired deferred diffusibility of color-providing substances may be obtained by two types of processing. In one, the latent color record images in the several emulsion layers are substantially simultaneously developed prior to the time the nonimmobilized color-providing substances in unexposed areas achieve the requisite diffusibility. In the second type of processing, the integral multilayer photosensitive element is processed layerwise, one emulsion layer being develop-ed and the color-providing substances associated therewith, but not immobilized by development, rendered diffusible to the image-receiving layer substantially prior to the time development and diffusion occurs in another layer. In certain instances, an integral multilayer photosensitive element may be so constructed as to utilize both types of processing techniques.

It will be noted that certain embodiments of this invention utilize the ability of a developing agent to develop a latent image contained in an exposed silver halide emulsion before a color-providing substance associated with said emulsion is sufficiently dissolved by a liquid processing composition to become diffusible. Where, as in the preferred embodiment, the color-providing substance is also the developing agent, e.g., a dye developer, such developer may be rendered effective to reduce adjacent exposed silver halide before unoxidized dye developer is sufficiently solubilized to be rendered diffusible.

As previously noted, development of a latent color record image results in an imagewise distribution of diffusible or nonimmobilized color-providing substance in unexposed areas of the emulsion. Immobilization of a color-providing substance may be due to a change in solubility resulting from the development, particularly where the color-providing substance is also a developer; to a barrier erected by tanning or hardening of the emulsion carrier due to the development; to a reaction with an immobile oxidized developer agent; etc.

As previously noted, the preferred color-providing substances are dye developers. The desired imagewise distribution of diffusible dye developer results from the immobilization of the dye developer oxidized in developing the latent image.

As examples of suitable dye developers, mention may be made of 2 naphthylazohydroquinone, 1 phenyl 3- methyl 4 [p (2',5 dihydroxyphenethyl) phenylazoJ-S-pyrazolone and phenylazohydroquinone, for yellow; 2-hydr0xynaphthylazohydroquinone, 2-[p-(2',5'-dihydroxyphenethyl)-phenylazo] 4 methoxy-l-naphthol and 1-amino-4-phenylazo-2-naphthol, for magenta; 1,4- bis (2,S dihydroxyanilino) anthraquinone, 1,4 bis- [[3 (2",5' dihydroxyphenyl) ethylamino] anthraquinone and 1,4 bis [/3 (2',5' dihydroxyphenyl)- propylamino]-anthraquinone, for cyan.

In lieu of creating the positive image dye by a coupling reaction between an oxidized color developer and a color coupler, one may form the desired dye by the reaction of unreacted coupler with a stabilized diazonium salt. It is well known that stabilized diazonium salts readily react in an alkaline environment with certain types of color couplers to provide a colored azo compound or dye. In such an embodiment a nondilfusing silver halide color developer is disposed in the photosensitive emulsion and a suitable phenolic or naphtholic type coupler is associated with said emulsion. Each coupler employed should be of a character which is dispersible or soluble in a processing liquid and reactable with the oxidation prodnet of the silver halide color developer and also of a character which is reactable with the stabilized diazotized salt to provide a dye of the desired color. The diazotized salt is disposed in the image-receiving layer and is available for reaction and coupling with unreacted color coupler which diffuses from unexposed portions of the negative.

In another embodiment, one may use as a color-providing substance 2. coupling dye, i.e., a complete dye which is capable of coupling with the oxidation product of a color developer, e.g., diethy-l p-phenylene diamine, to form an immobile dye. The desired imagewise distribution of diffusible color-providing substance results from the immobilization of the coupling dye in situ with the developed image as a result of the coupling reaction. Preferably, the coupling dye possesses the requisite color and may be utilized in the image-receiving layer without further reaction.

Dyes, i.e., coupling dyes, which are particularly suited for reaction with an oxidation product of a color developer are found in those dyes having an open position on a ring, which position is para to a hyd-roxyl or an amino group, or those dyes having a reactive methylene group. Many suitable dyes coming within this classification are found among the azo, pyrazolone and triphenyl methane dyes, as is well known in the art. By way of illustration, mention may be made of waterand alkalisoluble dyes such as Fast Crimson 6BL (Cl. 57) as well as water-insoluble but alkali-soluble dyes such as 1,5-dihydroxynaphthalene-4-azobenzene.

In lieu of a coupling'dye, one may also use dyes having an azo substitutent which is displaceable by reaction with oxidized photographic developer. Examples of such dyes are open chain reactive methylene compounds having an azo substituent attached to the reactive methylene group, compounds having a heterocyclic system containing an azo substituted methylene group and an adjacent carbonyl group as part of the ring structure, and phenolic compounds having an azo substituent attached to the phenol nucleus in a position para to the hydroxyl group; see U.S. Patents 2,453,661; 2,455,169; 2,455,170 and 2,521,908. By suitable selection of compounds of this type or by the addition of solubilizing groups, one may have an initially dilfusible dye which may be rendered immobile =by reaction with the oxidized developer. Thus, one may place the solubilizing groups, e.g., sulfo, on the azo substituent. In exposed areas, the coupling reaction with oxidized developer would thus remove the solubilizing groups and give an immobile product, while the dye in unexposed areas would be diffusible.

It is further contemplated to utilize, as a color-providing substance, a complete dye which is immobilized by tanning or by otherwise reducing the permeability of the emulsion by oxidized developer, whereby outward diffusion of the dye is prevented.

The use of conventional color couplers and color developers is also contemplated as within the scope of this invention. Preferred couplers for this embodiment of the invention are those which form azomethine, indaniline and indophenol dyes when reacted with a silver halide secondary color developer in the presence of an oxidizing agent. Such couplers may comprise nitriles, acyl nitriles. thioindoxyls, cyanaoetanilides, pyrazolones, phenols, naphthols, substituted ketones, esters and acyl acetanilides. Particularly suitable coupers which react with the oxidation product of a color developer to provide dyes are 2,4-dichloro-1-naphthol, for cyan; 1-p-nitrophenyl-3-methyl-5-pyrazolone and 1-phenyl-3-butyramido-5-pyrazo1one, for magenta; and acetoacet-Z,5-dichloranilide, acetoacet-Z- 'chloranilide and benzoylacetanilide, for yellow.

Suitable silver halide color developers for use with the just-described couplers comprise such secondary developing agents as the p-phenylene diamines and other characterized by their ability when oxidized to condense with couplers to form dyes of the above type. Combinations of color developers and couplers which form the least mobile dyes are preferred since such combinations give the cleanest highlights and the sharpest detail to the positive image. As an illustrative example of a standard color developer with which the invention may be practiced, mention may be made of Z-amino-S-diethylamino toluene.

Other suitable color-providing substances include leuco dyes which are capable of developing a latent silver halide image and whose oxidation product is a dye. Examples of such leuco dyes include leuco indophenols, e.g., 2-chloro- 4-(4-diethylamino-2'-methylanilino)-5-nitro-l naphthol hydrochloride, for cyan; leu-coquinizarin, for yellow; and leuco azomethines, e.g., l-phenyl-3-methyl-4-(2'-methyl- 4'-diethylamino)-anilino-5-pyrazolone hydrochloride, for magenta. One may also utilize self-coupling developers, that is, developers which couple with their oxidation product to give dyes.

Where color-providing substances are utilized which require oxidation to provide the desired color, this oxidation may be effected by aerial oxidation after diffusion. Preferably, the image-receiving element has incorporated therein an oxidizing agent for the purpose of speeding up dye image formation, and providing full density insmediately upon stripping. The incorporation of an oxidizing agent in the image-receiving element is described in US. Patent No. 2,559,643 issued to Edwin H. Land. As examples of suitable oxidizing agents, mention may be made of peroxy compounds such as sodium or potassium perborate, and compounds having polyvalent metallic elements in higher valent form, such as copper, iron or cerium, wherein the metallic element is in higher valent form. Examples of these latter mentioned agents are cupric salts such as cupric sulfate. Another suitable oxidizing agent is benzoyl peroxide.

Deferred diifusibility may be provided by incorporating the color-providing substances in an environment which initially prevents diffusion but which, by action of a liquid processing composition thereon, permits diffusion to occur after a suitable initial development period. The environment is so constituted that application of a liquid processing composition renders the developing agent substantially immediately effective for development without rendering said color-providing substances soluble enough to be immediately diffusible. As the processing continues, the color-providing substances which are not immobilized as a result of development are released for transfer.

In one embodiment, a color-providing substance may be incorporated in a water-immiscible material which is slowly permeable by alkaline solutions. One means of so incorporating color-providing substances is to emulsify them in particles of a liquid plasticizer which is preferably a high boiling, waterand alkali-immiscible liquid. Due to a greater afiinity of the color-providing substance for the liquid processing composition than for the liquid plasticizer in which it is emulsified, the color-providing substance is rendered increasingly ditfusible by a differential extraction process. An example of a suitable liquid plasticizer is tricresyl phosphate. When a color-providing substance is incorporated in the form of particles or droplets, it isdesirable that such particles be of a relatively coarse nature such that their covering power is relatively low and therefore they do not substantially affect the speed of the silver halide emulsion with which they are associated.

If desired, one may utilize a slowly hydrolyzable material, such as described below, in lieu of the previously mentioned high boiling liquid plasticizers where it is desired to incorporate the color-providing substances in the form of particles.

Another method of effecting deferred diffusibility by utilizing the difference between the rate of development and the rate of solubilization of color-providing substances is by incorporating the color-providing substance, e.g., a dye developer, in a particle such that the color-providing substance is surrounded by silver halide. In exposed areas the color-providing substance would be immobilized by the development reaction before it became sufficiently solubilized to diffuse. Such particles may be utilized in a binder, e.g., carboxymethyl cellulose, in which the nonimmobilized color-providing substance may move freely. Particles containing redand green-sensitive silver halide are preferably provided with a suitable yellow filter.

Alternatively, one may utilize a color-providing substance, e.g., a dye developer, which is solubilized immediately but has a slow rate of diffusion, so that it may be immobilized in exposed areas before it is able to diffuse.

One may also grind a dye developer into fine particles which are then dispersed in, on or behind the emulsion, in lieu of incorporating it in a droplet or particle of a high boiling liquid plasticizer or a slowly hydrolyzable material. It has been found that a dye developer utilized in the form of such fine particles apparently is more slowly dissolved than if molecularly dispersed, thus permitting one to effect the desired deferred diffusibility. These ground particles of dye developer should be of a relatively coarse nature, so as to have a relatively low covering power.

In a further embodiment of the invention, a white pigment may be utilized in forming particles of color-providing substances in lieu of a high boiling liquid plasticizer or a slowly hydrolyzable material. This may be accomplished by treating a pigment wettable by organic solvents, such, for example, as titanium dioxide, with an organic solution of the desired color-providing substance, after which the pigment is dried in the form of fine particles. These particles may then be finely dispersed in a photosensitive silver halide emulsion without adversely affecting the emulsion speed. The nonimmobilized color-providing substances are rendered diffusible by being dissolved in the liquid processing composition.

In another embodiment of this invention, a slowly hydrolyzable material may be used as a barrier layer separating an outer emulsion layer and its associated colorproviding substance from an inner emulsion layer and its associated color-providing substance. Permeation by the liquid processing composition initiates development of the latent color record image and also hydrolysis of the barrier material. By employing a barrier material whose rate of hydrolysis is slower than the rate of development of the latent image, it is possible to effect the processing in a stepwise or layerwise manner. The color-providing substances may be associated with the appropriate emulsions in any suitable manner, for example in a layer in, on or behind the emulsion, in the form of particles dispersed through the emulsion, etc.

Where the processing is effected in a stepwise manner using a slowly hydrolyzable barrier material, it may be desirable to incorporate an alkaline material of the requisite strength for effecting the hydrolysis elsewhere than in the liquid processing composition. It will be noted that stepwise processing, e.g. by the use of a barrier layer between each set of photosensitive emulsion layers and their associated color-providing substances, permits development of the latent color record image in an emulsion layer and diffusion of the resulting imagewise distribution of diffusible color-providing substances to be substantially completed prior to initiation of development and diffusion in another emulsion layer. Thus, where the color-providing substances are dye developers, an unoxidized dye developer being diffused from an inner emulsion layer is not trapped by development of exposed but undeveloped silver halide grains in an outer emulsion layer, while unoxidized dye developer from an outer emulsion layer has diffused to the image-receiving layer and is unavailable for rearward diffusion to participate in the development of an inner emulsion layer.

Another means of effecting this type of layerwise processing is by theuse of a barrier layer which is slowly permeated by the liquid processing composition, such that permeation of the liquid processing composition from an outer emulsion layer into the next inner emulsion layer is deferred until processing of said outer emulsion layer is substantially complete. One may employ, as a slowly permeable barrier layer, a layer of material which is slowly dissolved by a solvent therefor contained in the liquid processing composition. An example of another suitable layer for this purpose is a copolymer of methyl methacrylate and methacrylic acid which is rendered permeable more slowly than development occurs. Other suitable barrier layers may be prepared by incorporating a slowly alkali-soluble material, such as benzoic anhydride, into a polymer so that the permeability of such polymer to an alkaline solution is dependent on the rate at which the slowly alkali-soluble material is dissolved.

One may also control the diffusion availability of nonimmobilized color-providing substances by developing the latent images at a pH which is low enough to permit development to occur without rendering nonimmobilized color-providing substances diffusible, and thereafter releasing an alkali capable of providing a sufficiently higher pH at which the nonimmobilized color-providing substances are rendered diffusible. Thus, one may use a weak alkali such as sodium carbonate or phosphate to initiate development without rendering the color-providing substances diffusible. After a suitable interval, a stronger alkali such as sodium hydroxide may be released to render the nonimmobilized color-providing substances diffusible. In this embodiment, one may omit barrier layers between each emulsion layer and its associated color-providing substance, whereby development of the several emulsions is accomplished substantially simultaneously, followed by introduction or release of the stronger alkali to render diffusible the several nonimmobilized color-providing substances.

In accordance with the last-mentioned embodiment, one may introduce the stronger alkali by application subsequent to the application of the weak alkali. Thus, one may use a film unit containing two pods or containers, rupture of one such container being utilized to apply the weak alkali followed by rupture of the second container after a suitable interval to apply the stronger alkali. The use of two containers to release different compositions at different stages of processing is disclosed and claimed in the copending application of Edwin H. Land, Ser. No. 299,358, filed July 17, 1952 now US. Patent No. 2,846,309 issued Aug. 5, 1958. Such a two-stage application may be modified by having the liquid processing composition contained in the first ruptured container merely an aqueous composition effective to permeate the photosensitive element and release a weak alkali contained therein. One may also incorporate the strong alkali in the integral multilayer photosensitive element in such a way as to be slowly released by the action of a liquid processing composition containing a weak alkali.

A further method of utilizing a weak alkali to initiate development followed by the introduction of a strong alkali to render the nonimmobilized color-providing substances diffusible utilizes an outermost layer which permits water, but not an alkali, to pass through. The water of the liquid processing composition permeates this layer and solubilizes a weak alkali present in the photosensitive element, whereby development of the latent color record images is initiated. This outer layer reacts slowly with a strong alkali initially present in the liquid process ing composition and, after an interval of time sufficient to permit the necessary minimum development, becomes sufiiciently permeable to the strong alkali to permit it to permeate the photosensitive element and render the nonimmobilized color-providing substances dilrusible. Such a layer may be a thin layer of cellulose acetate or cellulose nitrate, which is slowly saponified by the strong alkali. Another suitable material is a polymeric substance containing a slowly alkali-soluble material, such as the previously mentioned benzoic anhydride-containing polymers.

Deferred dilfusibility of color-providing substances may be accomplished also by the use of a temporary mordant mechanism, i.e., a color-providing substance may be associated with a substituent or substance which renders it temporarily insoluble, in lieu of the previously discussed barrier-type mechanism. Application of a liquid processing composition slowly renders the temporary mordanted color-providing substances difiusible, as by hydrolyzing off an insolu'bilizing substituent such as an amine mordant. One may also utilize a layer of hydrolyzable nylon dispersed throughout the emulsion to temporarily mordant a color-providing substance. In lieu of destroying the temporary mordant, one may use an image-receiving layer which has substantially more aflinity for the nonimmobilized color-providing substance than does the temporary mordant.

Still another method of deferring the diffusibility of nonimmobilized color-providing substances, e g., dye developers, is by the temporary formation of salts of such color-providing substances, which salts are substantially insoluble in the liquid processing composition. In such an embodiment, the liquid processing composition may contain a reagent which forms an insoluble salt of the dye developer as it permeates the photosensitive element, thus temporarily preventing unoxidized dye developer from diffusing to the image-receiving element without interfering in the development of the latent image. A reagent capable of converting this insoluble salt to a salt soluble in the liquid processing composition is disposed behind the innermost strata of emulsion and/or dye developer. Permeation of the liquid processing composition into the layer containing this soluble-salt-forming reagent solubilizes it and permits to to diffuse outwardly and form the soluble salt of the dye developer. As an illustration, the insoluble-salt-forming reagent may be a metal hydroxide which is soluble in water and forms an alkaliinsoluble salt, e.g., barium or calcium hydroxide, and which may replace a part of the alkali in the liquid processing composition, and the soluble-salt-forming reagent may be a source of sodium ions. As a modification of this technique, it is also contemplated that the dye developer may initially be present in the photosensitive element in the form of such an insoluble salt.

As a further method of obtaining the desired deferred diffusibility of nonimmobilized color-providing substances, one may temporarily suppress their solubility in the liquid processing composition. In such an embodiment, one may include in the liquid processing composition a solubilitysuppressing salt, e.g., sodium sulfate. After the requisite development has occurred, the suppressed solubility may be eliminated by precipitating the sodium sulfate, or by reacting it with a material, contained in an innermost layer, which will form a salt having less solubility suppression efiect. Examples of such materials include barium citrate and barium acetate.

It is further contemplated to utilize unoxidized or unexhausted developing agent to effect the release of nonimmobilized color-providing substances in unexposed regions of the emulsion. In one such embodiment, the colorproviding substance may be incorporated in aparticle or envelope of pre-exposed silver bromide which is more slowly developable than the exposed silver halide .of tilt emulsion. In exposed areas, the developer is exhauster without developing the pre-exposed silver bromide of sucl particles, thus keeping immobile the color-providing substance in such particles. In unexposed areas the developer reduces the pre-exposed silver bromide, so changing the nature of the particle as to release the color-providing substance for diffusion. As an alternative, the color-providing substance may be incorporated in a particle or envelope or a silver complex precipitant, such as zinc sulfide, and a silver halide solvent incorporated in the liquid processing composition. In unexposed regions silver bromide is dissolved and migrates to the particles containing the color-providing substance where it reacts with the silver complex precipitant, releasing the color-providing substance contained therein for diffusion.

A further modification of the above use of the unexhausted developer to effect the desired deferred diffusibility involves the use of a color-providing substance, e.g., a dye of desired color, containing a reducible component, e.g., a quinone group, which component in its unreduced state renders the dye immobile, such dye being made diffusible by the reducing action of the unoxidized developer. Such a reducible component is more slowly reducible by the unoxidized developing agent than is the exposed silver halide but faster than the unexposed silver halide. In unexposed areas, the developing agent reduces this component, rendering the dye dilfusible. Where a quinone group is so used, the reduced quinone is preferably a weak developing agent and thus does not interfere with normal development. Such uses of unexha-usted developer comprise the subject matter of the c-opending application of Howard G. Rogers, Ser. No. 599,122, filed July 20, 1956 (now abandoned in favor of a continuation-in-part thereof, Ser. No. 825,359, filed July 6, 1959, now US. Patent No. 3,185,567 issued May 25, 1965).

In the previously described embodiments of this invention, it has been desirable to avoid participation by a nonimmobilized color-providing substance in the development of an emulsion other than that with which it is associated.

It is also within the scope of this invention to process an integral multilayer photosensitive element by a simultaneous permeation of the several emulsion layers by a liquid processing composition, wherein a difierent reaction is utilized in each layer to develop the several latent images. A process of this type may be described as a noninterfering process, since the several developing agents cannot interfere in the development of emulsions other than the one with which they are associated. Diffusion of the color-providing substances is deferred until after at least substantial development has occurred. This deferred difiusibility may be effected by utilizing the various techniques set forth in this specification. In such a process, the innermost emulsion layer of a three-color integral multilayer photosensitive element may utilize a nondiflusing tanning developer to develop the latent color record image therein. Tanning of the emulsion by the oxidized, nondiffusing tanning developer would be effective to prevent transfer, in exposed areas, of a dye initially present in a layer behind said emulsion. The middle and outermost emulsion layers may utilize a nondifiusing couplin developer, such, for example, as 4- amino-S-n-butoxydiethyl aniline or decyloxyamiuophenol, to control the transfer of a coupling dye associated therewith. Coupling dyes are dyes containing substituents which permit coupling thereof with the oxidation product of a color developer to form an immobile dye, as previously described. Alternativel the outermost emulsion layer maybe developed by a dye developer which may be introduced as an ingredient of the liquid processing composition. It may be desirable to utilize a layer behind this emulsion layer which will prevent permeation of the dye developer into inner emulsion layers. One may also utilize an outermost emulsion layer having properties such that the dye developer cannot permeate through all of said layer during the imbibition period. If desired, one may utilize an image-receiving layer which is only slowly permeated by the dye developer whereby imbibition of the dye developer is delayed and dye developer stain in the highlights is avoided.

In lieu of the use of a nondiffusible tanning developer in the innermost layer, one may alsouse a nondiffusible developer which possesses a free amino group as part of its developing function to harden a carrier material for silver halide such, for example, as a polymer which is normally permeable to alkaline Solutions but which can be made less permeable by a coupling reaction with an oxidized amino developer. One specific example of a polymer of this nature is a modified polyvinyl alcohol wherein positions on its chain have been substituted with phenol or naphthol groups and wherein the substituted phenols or naphthols have open positions for coupling, which positions are para to hydroxyl groups. Another example occurs where the polyvinyl alcohol has been substituted with a compound containing a reactive methylene group which is available for coupling. The incorporation of a light-sensitive silver halide in polymers of the character mentioned is well understood in the art, an example thereof being disclosed in US. Patent No. 2,397,- 864. As the coupling group forms the only substitution of the polymer, its penmeability to alkaline solutions is radically lowered upon coupling with the oxidation product of the nondiifusible amino developer.

In those embodiments of this invention wherein the exposed photosensitive element is processed using a polyhydroxy-type developing agent, e.g., a dye developer possessing a hydroquinonyl developing function, processing is preferably effected in the presence of a small amount of a short induction period-accelerating developing agent, for example, Metol (p-methylaminophenol) or Phenidone (lphenyl-3-pyrazolidone), hereinafter referred to as accelcrating developers. By a small amount is meant an amount insufficient to give any appreciable negative density by it self. Such an accelerating developer may be incorporated in the liquid processing composition or in the emulsion so that it is substantially immediately available for development upon application of the liquid processing composition. The accelerating developer appears to initiate development of the latent color record image before the principal developing agent, e.g., the dye developer, present in the photosensitive element, is sufficiently activated, e.g., solubilized, to begin development and the colorproviding substance rendered diffusible. Thus, one might refer to it as priming development. It appears that the oxidized accelerating developer is reduced or regenerated by reaction with unoxidized dye developer, apparently by an energy-transfer mechanism, immobilizing the dye developer substantially where the accelerating developer was oxidized by the exposed silver halide. The regenerated accelerating developer is thus made available to repeat the cycle. This reaction between the oxidized accelerating developer and the unoxidized principal developer may occur while the latter is still in an immobile condition, i.e., prior to its being solubilized by the liquid processing composition. The use of such accelerating developers has been found to greatly improve the contrast of the color record image and to give increased development rates with low mobility principal developing agents. It has been found to be particularly useful in controlling transfer of a dye developer disposed in an emulsion, since part of the dye developer nearest to the outer surface of the emulsion might otherwise transfer before it was immobilized by adjacent exposed silver halide. This priming development, illustrated by accelerating developers, and explainable by an energy-transfer mechanism, facilitates the creation of the desired deferred diffusibility by rapidly initiating the imagewise development necessary to control the transfer of the color-providing substances.

In lieu of applying a dye developer in the form of a continuous layer, it may be desirable to apply the dye developer in the form of minute spots, as by printing with a suitable halftone plate. Such spots may be approximately 0.0001 of an inch in thickness. As a suitable carrier material for the dye developers, mention may be made of cellulose acetate hydrogen phthalate. In some instances it may be desirable to use a carrier material which will control the release of the dye developer, e.g.. a copolymer of methyl methacrylate and methacrylic acid, as previously discussed. Utilization of the dye developer in such spots has the advantages over a continuous layer of permitting faster permeation of the liquid processing composition as well as reduced danger of inward diffusion of dye developer. Such spots would give greater resolving power than if one uses particles or grains, as well as a more efiicient distribution of the dye developer. As will be apparent, this technique is applicable to both the two outermost dye developers, whereas no particular advantage would result from its use with the innermost dye developer.

A two-layer integral multilayer photosensitive element may also be constructed and processed in a similar manher.

The techniques of this invention may be utilized in both two-color and three-color photographic processes. The sensitivities of the several emulsions may be selected in accordance with well-known photographic principles. For example, an integral multilayer photosensitive element suitable for use in two-color processes may have one emulsion sensitized to the blue and green portions of the spectrum, and the other emulsion to the orange and red portions of the spectrum. The color-providing substances associated with such two-color photosensitive elements are, respectively, orange and cyan. In some instances it may be desirable to utilize a yellow filter layer over the emulsion layers in accordance with known techniques.

Suitable three-color integral multilayer photosensitive elements may comprise an outer blue-sensitive emulsion separated by a yellow filter layer from inner red-sensitive and green-sensitive emulsion layers. Where a yellow dye developer is utilized in processing the blue-sensitive outer emulsion layer, a layer of such dye developer behind the blue-sensitive emulsion may be utilized as an efficient yellow filter. Where the color-providing substance associated with the blue-sensitive emulsion is dispersed therein or otherwise utilized in such a way as to be incapable of effectively functioning as a yellow filter, a suitable yellow filter layer may be used. In a preferred embodiment, a yellow filter layer may be prepared using a pigment comprising a suspension of a benzidine yellow, such as that commercially avialable under the name of Padding Yellow GL from Textile Colors Division, Interchemical Corporation, Hawthorne, NJ.

The liquid processing composition utilized to process the exposed photosensitive element comprises at least an aqueous solution, and may contain an alkaline reagent. If the liquid processing composition is to be applied to the exposed photosensitive element by being spread thereon, preferably in a relatively thin, uniform layer, it may also include a viscosity-increasing compound constituting a film-forming material of the type which, when said composition is spread and dried, will form a relatively firm and relatively stable film. A preferred film-forming material is a high molecular weight polymer such as a polymeric water-soluble ether which is inert to an alkaline solution as, for example, a hydroxyethyl cellulose or sodium carboxymethyl cellulose. Other film-forming materials or thickening agents whose ability to increase viscosity is substantially unaffected when left in solution for a long period of time may also be used. The filmforming material is preferably contained in the processing composition in suitable quantities to impart to said composition a viscosity in excess of 1,000 centipoises at a temperature of approximately 24 C. and preferably of the order of 1,000 to 200,000 centipoises at said temperature. Illustrations of suitable liquid processing compositions may be found in the several patents and copending applications herein mentioned, and also in the examples hereinafter given. Under certain circumstances, it may be desirable to apply the liquid processing composition to the integral multilayer photosensitive element prior to exposure in accordance with the technique described in the copending application of Edwin H. Land, Ser. No. 498,672, filed Apr. 1, 1955 now US. Patent No. 3,087,- 816 issued Apr. 30, 1963.

It will be noted that whether an alkaline material is present in the liquid processing composition, and whether such alkaline compound is a strong or weak alkali, will depend upon the nature of the technique employed to create the desired deferred mobility as discussed above.

Several embodiments wherein this invention may be practiced are illustrated in the accompanying drawings. References to particular color-providing substances in the description of these embodiments is intended to be illustrative only. While the preferred color-providing substances are dye developers and the several embodiments are illustrated by the use of dye developers, it is to be understood that other types of color-providing substances also may be employed, as set forth in this specification.

FIGURE 1 of the accompanying drawings diagram matically illustrates in cross section one example of an integral multilayer photosensitive element constructed in accordance with this invention. A support has coated thereon an innermost layer 11 of a cyan dye developer over which has been coated a layer 12 of a red-sensitive silver halide emulsion. A middle layer 14 of a greensensitive emulsion 14a containing discrete particles 14b of a magenta dye developer is separated from the innermost red-sensitive emulsion layer 12 by a gelatin interlayer 13. The outermost layer 16 comprises a blue-sensitive silver halide emulsion 16a having dispersed therein discrete particles 16b of a yellow dye developer, and has been applied over a gelatin layer containing a yellow filter. In processing such an integral multilayer photosensitive element, a container 17 is ruptured and a liquid processing composition contained therein is spread between the exposed, integral, multilayer photosensitive element and a superposed image-receiving element 18. The alkaline liquid processing composition is permeated into the exposed photosensitive element whereby the dye developers are rendered eifective to develop the exposed silver halide.

Particles

14b and 16b containing magenta and yellow dye developers, respectively, comprise particles, globules or droplets of a material which permits the liquid processing composition to activate dye developer contained therein to reduce exposed silver halide but which restricts the ability of unreacted dye developer contained therein to diffuse and transfer to the imagereceiving element until after at least substantial development of the exposed silver halide has occurred, at which stage of processing, diflusion of unreacted dye developer from an inner layer may be etfected without interfering in the development of I a dilferently sensitized emulsion.

Where the color-providing substances are utilized in the form of particles from which they are slowly released by action of the alkaline liquid processing composition, the particles may be prepared from suitable plasticizers, or suitable, slowly hydrolyzable materials, such as esters, or mixtures thereof. In addition to the previously mentioned plasticizer, tricresyl phosphate, other suitable materials and mixtures for use in forming such particles include:

benzoic anhydride+tricresyl phosphate n-butyl oxamate+tricresyl phosphate ethyl oxamate-i-tricresyl phosphate n-butyl oxalate-i-tricresyl phosphate n-butyl oxalate .The following example describes the preparation and processing of a two-color, integral, multilayer photosensi tive element constructed in a manner analogous to th three-color element illustrated in FIG. 1 and describe above, and given only to illustrate the techniques b] which this invention may be practiced.

The emulsion sensitivities as well as the color prop erties of the color-providing substances, e.g., dye de velopers, employed in the following example and alsc in the other examples of this specification are intended only to illustrate the techniques employed, without trying to obtain accurate color reproduction of the photographed subject matter.

Example 1 An integral multilayer photosensitive element is prepared by coating a gelatin-coated film base with a composition comprising 4% of a yellow dye developer (napht-hylazohydroquinone) in a 4% solution of cellulose acetate hydrogen phthalate in an :20 mixture, by volume, of acetone and methanol. After this coating has dried, a green-sensitive silver halide emulsion is applied, followed by a thin layer of gelatin using a 2% gelatin solution. A layer of red-sensitive emulsion containing a cyan dye developer dispersed therein is applied over the dried gelatin layer. The dispersion of cyan dye developer in the red-sensitive emulsion is prepared by emulsifying 1.35 g. of 1,4-bis-[B(2'-,5'-dihydroxyphenyl) ethylamino]-anthraquinone, 4 cc. of n-butyl oxalate, 6 cc. of butylacetate and 15 cc. of 2% gelatin solution. 10 cc. of the thus prepared emulsion is added to 35 cc. of water containing a small amount of an emulsifying agent, and this composition is thoroughly mixed with 10 cc. of a red-sensitive silver halide emulsion. The thus prepared red-sensitive silver halide emulsion containing dispersed particles of cyan dye developer is then coated over the gelatin interlayer.

After exposure, the integral multilayer photosensitive element is processed by spreading an aqueous liquid proc essing composition comprising:

Percent Sodium hydroxide 2.5 1-phenyl-3-pyrazolidone 0.2 Potassium bromide 0.2 Sodium carboxymethyl cellulose 4.5

between the exposed integral multilayer photosensitive element and an image-receiving element comprising a coating of 4% Nylon Type F8 (trade name of E. I. du Pont de Nemours & 00., Wilmington, Del., for N-methoxymethyl polyhexamethylene adipamide) applied over a cellulose acetate-coated baryta paper, as said elements are brought into superposed relationship. After an imbibition period of approximately five minutes, the imagereceiving element is stripped from the developed photosensitive element revealing a yellow, cyan and green positive image.

Suitable structure for a two-color diffusion transferreversal process is illustrated in FIG. 2, wherein an inner layer 21 containing particles 21a of a cyan dye developer and particles 21b of an orangeand red-sensitive emulsion has been applied to a support layer 20. An outer layer 22, separated from said inner layer 21 by a barrier layer 23, comprises a mixture of particles 22a of an orange dye developer and particles 22b of a blueand greensensitive emulsion. When processed by application of a liquid processing composition, the exposed blueand green-sensitive emulsion particles of said outer layer 22 are developed by the orange dye developer dispersed therein. Unoxidized orange dye developer is ditfused to a suitable image-receiving layer, not shown. After at least substantial development of said outer layer 22 has occurred, the liquid processing composition permeates said inner layer 21 and renders the cyan dye developer dispersed therein as particles 21a eifective to develop exposed orangeand red-sensitive emulsion particles 21b,

unoxidized cyan dye developer being rendered diffusible to the image-receiving layer.

As previously noted, the term layer as herein used also contemplates a stratum containing a combination of two differently photosensitized emulsions. Such a stratum may comprise a mixture of two sets of particles of hardened gelatin, each encasing particles of a suitably sensitized emulsion together with its appropriate colorproviding substance. These hardened gelatin particles may be formed by procedures similar to those taught in US. Patent No. 2,618,553.

The term layer" also contemplates a stratum comprising two sets of selectively sensitized minute photosensitive elements arranged in the form of a photosensitive screen, such as illustrated in FIG. 3 of the drawings.

Referring to said figure, a photosensitive screen 38 comprising minute red-sensitized emulsion elements 32 and minute green-sensitized emulsion elements 34 arranged in side-by-side relationship in a screen pattern, and having associated therewith

strata

31 and 33 of cyan and magenta dye developers, respectively, is disposed on a support layer 30. Suitable photosensitive screens for use in this embodiment may be prepared as disclosed in the aforementioned application Ser. No. 415,073 (now abandoned in favor of a continuation-in-part thereof, Ser. No. 748,421, now US. Patent No. 2,983,606 issued May 9, 1961) and also in the copending .application of Edwin H. Land, Ser. No. 448,441, filed Aug. 9, 1954, now US. Patent No. 2,968,534 issued Jan. 17, 1961. A barrier layer 35 separates said screen layer 38 from a layer 36 of a yellow dye developer over which is applied an outer layer 37 of a blue-sensitive emulsion. In processing an integral multilayer photosensitive element such as contemplated in FIG. 3, the liquid processing composition permeates the blue-sensitive emulsion layer 37 and its associated layer 36 of yellow dye developer. The barrier layer 35 serves to delay permeation of the liquid processing composition into the photosensitive screen layer 38 until at least substantial development of the blue-sensitive emulsion layer 37 has occurred. The redand green-sensitized elements of the photosensitive screen layer 38 are then developed simultaneously and unoxidized cyan and magenta dye developers simultaneously rendered diffusible from the unexposed areas thereof. It will be apparent that the color-providing substances associated with the photosensitive screen may be incorporated in the emulsion or in separate strata behind the emulsion strata.

It will be noted that sidewise diffusion may be advantageously employed to cause an overlapping or intermingling on the positive image-receiving layer of col-orforming substances diffused from the photosensitive screen inner layer of a negative, integral, multilayer, photosensitive material, e.g., photosensitive screen 38 of FIG. 3. This overlapping of these color-providing substances is essential in order to obtain subtractive mixtures of the colors needed to form the desired multicolor image on the image-receiving layer. In this connection, it is desirable that each unit portion of such color-providing substance transferred to the image-receiving layer be disposed over a surface area of the image-receiving layer which is greater in magnitude than the surface layer of the negative from which said unit portion of color-providing substance originates. The extent of the overlap is controlled by the spacing employed between the negative and positive elements while undergoing processing. This spacing apart of the negative and positive elements will, of course, be dependent upon the thickness of the liquid processing composition spread between and in contact with said elements. The thickness of the layer of liquid composition will, in turn, be dependent, as will be well understood by the art, upon the liquid volume being spread, the viscosity of the liquid, the separation or gap between the pressure rolls or other spreading means and similar interrelated factors.

FIG. 4 of the accompanying drawings illustrates an integral, multilayer, photosensitive element wherein development and diffusion of the nonimmobilized color-providing substances is performed layerwise, i.e., development and diffusion of nonimmobilized color-providing substances is substantially completed in one layer before being initiated in an adjacent layer. Support layer 40 has coated thereon a layer 41 of a cyan dye developer and a layer 42 of a red-sensitive emulsion. Barrier layer 43 separates the layer 42 of red-sensitive emulsion from a layer 44 of a magenta dye developer and its associated layer 45 of a green-sensitive emulsion. A blue-sensitive emulsion layer 48 and its associated layer 47 of a yellow dye developer is separated from the green-sensitive emulsion by a barrier layer 46. An example of a suitable material for barrier layers 43 and 46 is gelatin.

It is further contemplated that the structure shown in FIG. 4 may be modified by disposing a layer of dye developer between two layers of commonly sensitized emulsion, e.g., a layer of a yellow dye developer may be cast between two layers of a blue-sensitive emulsion. The layer of magenta dye developer may be similarly cast between two layers of a green-sensitive emulsion. In such an embodiment, the layer of dye developer may effectively serve as a filter for an inner emulsion layer. Casting the layer of dye developer between two layers of a commonly sensitized emulsion may also permit one to use thinner barrier layers between the several emulsion layers or to even omit such barrier layers completely, since the innermost of the two emulsion layers will function as a barrier layer to reduce or eliminate inward diffusion of the dye developer.

The following example illustrates the preparation and processing of a two-color, integral, multilayer, photosensitive element similar in structure to the three-color element shown in FIG. 4, and is given only to illustrate the techniques of this invention.

Example 2 An integral, multilayer, photosensitive element is prepared by coating a gelatin-coated film base with a 4% solution of 1,4 bis [,8 (2',5'-dihydroxyphenyl)-propylamino]-anthraquinone in a solution of 4% cellulose acetate hydrogen phthalate in a 50:50 mixture, by volume, of acetone and tetrahydrofuran. A red-sensitive emulsion is then applied, followed by a gelatin layer cast from a 4% aqueous gelatin solution. A layer of yellow dye developer is then applied using a solution of 1.5% of naphthylazohydroquinone in a 4% solution of cellulose acetate hydrogen phthalate in a 50:50 mixture, by volume, of acetone and tetrahydrofuran, followed by a layer of a slightly diluted, green-sensitive emulsion. The thus prepared photosensitive element is exposed and processed by application of an aqueous liquid processing composition comprising:

Percent Sodium hydroxide 2.0 1-phenyl-3-pyrazolidone 0.2 Potassium bromide 0.2 Sodium carboxymethyl cellulose 4.5

The liquid processing composition is applied by spreading between the exposed, integral, multilayer, photosensitive element and an image-receiving element, similar to that described in Example 1, as said elements are brought into superposed relationship. After an imbibition period of ap-' proximately 1 /2 minutes, the image-receiving element is stripped from the developed photosensitive element. The positive dye image in the image-receiving element has yellow, cyan and green portions, thus indicating that the desired color separation has been accomplished.

Permeation of the liquid processing composition into the exposed, integral, multilayer, photosensitive element whereby that element is processed layerwise may be effected by appropriate selection of the thickness of each photosensitive layer, as well as by the selection of emulsions which are of themselves slowly permeable, or by a combination of both of these practices. Additionally, one may utilize the increase of thickness of a photographic emulsion due to its swelling when wetted with the processing composition as a means of controlling the permeation of the'liquid processing composition. Furthermore, various materials may be added to a photosensitive emulsion layer to retard the rate of permeation by the liquid processing composition. Examples of suitable materials for this purpose include gum arabic, polyvinyl alcohol, and other materials which are compatible with gelatin.

Referring to FIG. 5, there is illustrated an integral, multilayer, photosensitive element wherein the several emulsion layers of an exposed photosensitive element are intended to be processed by dilferent or noninterfering development reactions in each of said layers. A support layer 50 carries a layer 51 of a cyan dye over which is coated a layer 52 of a red-sensitive emulsion containing a nondiffusing, tanning developer, such as a long chain alkyl-substituted hydroquinone. There is next applied a layer 53 of a magenta coupling dye associated with a layer 54 of a green-sensitive emulsion containing a nondiffusing color developer. Suitable procedures for providing a dye image by the use of coupling dyes, i.e., complete dyes which are soluble in alkaline solution and which are reactable with the oxidation product of a color developer, are disclosed in the copending application of Howard G. Rogers, Ser. No, 358,012, filed May 28, 1953, now U.S. Patent No. 2,774,668 issued Dec. 18, 1956, and also in a continuation-in-part thereof, Ser. No. 613,691, filed Oct. 3, 1956, now U.S. Patent No. 3,087,817 issued Apr. 30, 1963. Over the green-sensitive emulsion layer 54 is coated a yellow filter layer 55 followed by a layer 56 of a blue-sensitive emulsion. A yellow dye developer is contained in a liquid processing composition disposed in a rupturable container 57 which is adapted, upon rupture, to release its contents for spreading across the exposed photosensitive element. Application of the liquid processing composition containing the yellow dye developer simultaneously effects development of the bluesensitive emulsion layer 56 and permeation of the greenand red-sensitive emulsion layers 54 and 52. The bluesensitive emulsion layer 56 is so constituted as to permit permeation of the alkaline processing composition, but not the yellow dye developer, to the inner greenand redsensitive emulsion layers 54 and 52. Where development occurs in the red-sensitive emulsion layer 52, the emulsion is tanned by the oxidized, nondilfusing tanning developer, thus preventing the cyan dye from dilfusing therethrough. Development of the exposed green-sensitive emulsion layer 54 by the nondiffusing color developer disposed therein immobilize's the magenta coupling dye in the exposed portions thereof. Unoxidized yellow dye developer remains free to diffuse from the unoxidized portions of the bluesensitive emulsion layer 56.

Suitable structure utilizing an insoluble-salt-forming mechanism for obtaining the desired deferred diffusibility is illustrated in FIG. 6. A support 70 has coated thereon a layer 69 comprising a soluble-salt-forming reagent or material, for example sodium sulfate or an ion exchange resin capable of yielding sodium ions. Over this is applied a layer '68 of a cyan dye developer followed by a layer 67 of a red-sensitive silver halide emulsion. A spatial barrier layer 66, which may be a layer of gelatin, silver halide emulsion or other material adapted to restrict inward diffusion of dye developer without restricting permeation of the liquid processing composition, separates the red-sensitive emulsion layer from a layer 65 of a magenta dye developer and its associated green-sensitive emulsion layer 64. Similarly, a spatial barrier layer 63, similar to the previously mentioned spatial barrier layer 66, separates the green-sensitive emulsion layer 64 from a layer 62 of a yellow dye developer and its associated layer 61 of a blue-sensitive emulsion. After exposure, a liquid processing composition 60 containing an insoluble-salt-forming reagent, such as barium hydroxide, and also preferably containing a small amount of an alkaline material, such as sodium hydroxide or diethylamine, is applied by rupture of its container. Permeation of this liquid processing composition into the exposed, integral, multilayer, photosensitive element renders the dye developers effective for development of the latent color record images, but also forms a salt of the unoxidized dye developer, which salt is substantially insoluble in the liquid processing composition. Permeation of the liquid processing composition into the innermost layer releases a soluble-salt-forming reagent or ion, which, as it dilfuses outwardly, converts the temporarily insolubilized, unoxidized dye developer into a salt which is soluble in the liquid processing composition and therefore ditfusible to the image-receiving element, and precipitates the insoluble-salt-forming reagent, e.g., the barium ion. It may be noted that in the process of precipitating barium ions by the release of sodium ions, the pH of the liquid processing composition may be increased due to the greater alkalinity of sodium hydroxide. Release of the soluble-salt-forming reagent is effected only after at least substantial development has occurred.

The following example illustrates the preparation and processing of a two-color, integral, multilayer, photosensitive element similar in structure to the three-color element shown in FIG. 6, and is given only as an illustration of this technique.

Example 3 An integral, multilayer, photosensitive element is prepared by coating a film base with an aqueous gelatin solution containing 1% sodium sulfate. Over this is applied a layer of a yellow dye developer cast from a solution of 4% naphthylazohydroquinone in a 4% solution of cellulose acetate hydrogen phthalate in a 50:50 mixture, by volume, of acetone and tetrahydrofuran, followed by a layer of a green-sensitive emulsion. A gelatin layer is then applied, using a 4% aqueous gelatin solution. Over this is applied a layer of cyan dye developer, using a solution comprising 3% of 1,4-bis-[fl-(2,5'-dihydroxyphenyl)-propylaminoJ-anthraquinone in a solution of 4% cellulose :acetate hydrogen phth-alate in a 50:50 mixture, by volume, of acetone and tetrahydrofuran, followed by a layer of a red-sensitive emulsion. After exposure, this photosensitive element is processed by application of an aqueous liquid processing composition comprising:

Percent Sodium hydroxide 1.5 Potassium bromide 0.2 '1 phenyl 3 pyrazolidone 0.2 Barium hydroxide 2.0 Sodium carboxymethyl cellulose 4.5

The liquid processing composition is applied by spread ing between the exposed, integral, multilayer, photosensitive element and an image-receiving element, similar to that described in Example 1, as said elements are brought into superposed relationship. After an imbibition period of approximately two minutes, the image-receiving element is stripped from the developed photosensitive element. The positive dye image in the image-receiving element has yellow, green and cyan portions, indicating that color separation has been effected.

Except in the lowest, i.e., innermost emulsion layer, it is undesirable that the carrier or binder material of the silver halide emulsion be rendered impermeable as by tanning, hardening, etc. Such hardening of the emulsion would prevent color-providing substances from diffusing outwardly from unexposed areas of an inner layer or layers. One may avoid such hardening by using a nontanning developer, an emulsion carrier or hinder whose permeability is unaffected by the oxidation product of the developing agent or, where one is using a normally tanning developer, sufficient sulfite to avoid undesirable tanning.

Although the structure of the integral, multilayer, photosensitive element has been illustrated as having emulsion layers from top to bottom sensitized to blue, green, and red portions of the spectrum, respectively, it is to be understood that the order of these emulsions may vary in accordance with well known practices in the art.

The emulsion layers or strata are approximately 0.0001 to 0.0005 of an inch in thickness, while the barrier layers may be approximately 0.00005 to 0.0002 of an inch thick. It will be apparent that the thickness of the barrier layer will vary according to the nature of the material used and the nature of the liquid processing composition.

Since the reaction development results in a lowering of the pH at the point of development, suitable precautions should be taken to ensure that the liquid processing composition possesses the requisite pH for developing each of the emulsions.

The color-providing substances are preferably selected for their ability to provide colors useful in carrying out subtractive color photography. The color-providing substances are used in a quantity per unit portion of emulsion sufficient to be completely immobilized by the development reaction as said unit portion is fully exposed. When one relies upon tanning or hardening of the emulsion to restrict diffusion of the color-providing substance, then such color-providing substance may be used in excess of said quantity. The color-providing substances are intended to be so distributed as to have a substantially uniform concentration for each unit surface area of the emulsion layer with which they are associated.

Where the color-providing substance in the form utilized in the integral multilayer photosensitive element possesses the desired subtractive color, it may effectively function as a filter for the light reaching an inner emulsion layer. For this purpose, the color-providing substance may be placed in, on or behind its respective emulsion layer. Preferably it is placed behind the emulsion, since dispersing such a colored substance in an emulsion may possibly reduce the exposure given inner portions of that emulsion layer.

In all products employed in the practice of this invention, it is preferable to expose the integral, multilayer, photosensitive element from the emulsion side. It is, therefore, desirable to hold said photosensitive element and the image-receiving element together at one end thereof by fastening means not shown but comprising hinges, staples, or the like in such manner that the photosensitive element and the image-receiving element may be spread apart from their processing positions illustrated in FIG. 1. Where the film unit is of the roll film type, said photosensitive element and image-receiving element are wound into separate rolls and the free ends of said rolls are connected together in the manner described. A camera apparatus suitable for processing roll film of the type just mentioned is provided by the Polaroid Land Camera Model 95A, sold by Polaroid Corporation, Cambridge, Massachusetts, or similar camera structure such, for example, as the camera forming the subject matter of US. Patent No. 2,435,717. Camera apparatus of this type permits successive exposure of individual frames of the photosensitive elements from the emulsion side thereof as well as individual processing of an exposed frame by bringing said exposed frame into superposed relation with a predetermined portion of the image-receiving element while drawing these portions of the film assembly between a pair of pressure rollers which rupture a container associated therewith and effect the spreading of the processing liquid released by rupture of said container, between and in contact with the exposed photosensitive frame and the predetermined, registered area of the image-receiving element.

The nature and construction of rupturable containers, such as container 17 of FIG. 1, is well understood in the art; see, for example, US. Patent No. 2,543,181, issued to Edwin H. Land on Feb. 27, 1951 and US. Patent No.

20 2,634,886, issued to Edwin H. Land on Apr. 14, 1953.

The image-receiving element comprises an image-receiving layer of opaque or transparent material which is liquid permeable and dyeable from alkaline solutions and which has been illustrated for purposes of simplicity as comprising a single sheet of permeable material, for example paper. This element, however, may comprise a support upon which at least one liquid-permeable and dyeable layer is mounted. The support layer may have a water-impermeable subcoat over which the stratum of permeable and dyeable material is applied. In certain instances, the dyeable layer may comprise a layer of liquid processing composition which is adapted to remain adhered to the support layer upon stripping.

A preferred material for the image-receiving layer is a nylon and preferably a nylon such as N-methoxymethyl polyhexamethylene adipamide which is available under the trade name of Nylon Type F8 from E. I. du Pont de Nemours & Co. Other materials suitable for imagereceiving layers comprise a paritally hydrolyzed polyvinyl acetate such as that commercially available under the trade name of Vinylite MA-28-18 from Bakelite Division, Carbide and Carbon Chemicals Co.; polyvinyl alcohol with or without plasticizers; baryta paper, i.e., a support having a baryta coating thereon; cellulose acetate with filler as, for example, one-half cellulose acetate and one-half oleic acid, and other materials of a similar nature, as is well known in the art.

While a rupturable container 17, such as has been illustrated with the film unit of FIG. 1, provides a convenient means for spreading a liquid processing composition between layers of a film unit whereby to permit the processing to be carried out within a camera apparatus, the practices of this invention may be otherwise effected. For example, an integral, multilayer, photosensitive element, after exposure in suitable apparatus and while preventing further exposure thereafter to actinic light, may be removed from such apparatus and permeated with the liquid processing composition as by coating the composition on said photosensitive element or otherwise wetting said element with the composition following which the permeated, exposed, photosensitive element, still without additional exposure to actinic light, is brought into contact with the image-receiving element for image formation in the manner heretofore described.

It is also to be understood that the invention may be successfully practiced without the use of a film-forming material in the liquid processing composition. As an illustration, a nonviscous liquid processing composition is particularly applicable with the processing technique last mentioned above and may be applied to the exposed photosensitive element by imbibition or coating practices and may be similarly applied to the image-receiving element before said elements are brought into superposed relation or contact for carrying out the transfer of nonimmobilized color-providing substances.

It is recognized that it has been previously proposed, in connection with color diffusion transfer-reversal processes, to utilize a retarding mechanism to effect substantial completion of development before the formation of the positive transfer image; see, for example, US. Patent No. 2,661,293, issued to Edwin H. Land on Dec. 1, 1953. Such disclosures are to be distinguished from the processes of this invention since they were concerned not with integral, multilayer, photosensitive elements but with the formation of monochromatic images, and sought only to delay the reaction of unreacted color developer and coupler on the image-receiving element. They were not concerned with deferring the diffusibility of nonimmobilized color-providing substances from an inner emulsion layer until after at least substantial development of an outer emulsion layer had occurred. Nor were such prior disclosures concerned with avoiding reaction of a developing agent in an emulsion layer other than that for which it is intended.

It is also recognized that it has been suggested, in connection with the preparation of photosensitive screen elements such as disclosed in the copending application of Howard G. Rogers, Ser. No. 358,011, filed May 28, 1953 (now abandoned in favor of a continuation-in-part thereof, Ser. No. 577,711, now US. Patent No. 3,019,124 issued Jan. 30, 1960), to control the penetration of the liquid processing composition. Such practice is distinguishable from the invention herein disclosed in that permeation controls utilized in the preparation of screen elements are intended to completely prevent permeation of a lower layer by the liquid processing composition during the imbibition period.

It has also been previously proposed in US. Patent No. 2,559,643, issued July 10, 1951 to Edwin H. Land, to use a tripack film structure for the negative photosensitive element in a diffusion transfer-reversal process. A tripack film structure utilizes a plurality of separable, individual emulsion layers held together in superposed relationship during exposure but processed separately, in conjunction with separate image-receiving layers, which layers are thereafter superposed in registered relationship on a common support. Such structure is readily distinguishable from the herein contemplated integral, multilayer, photosensitive element which is processed as a unit and in conjunction with a common image-receiving layer or element, and is in the nature of a monopack material.

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

Throughout the specification and appended claims the expression positive image has been used. This expression should not be interpreted in a restrictive sense since it is used primarily for purposes of illustration, in that it defines the image produced on the image-carrying layer as being reversed, in the positive-negative sense, with respect to the image in the photosensitive element. As an example of an alternative meaning for positive image, assume that the photosensitive element is exposed to actinic light through a negative transparency. In this case the latent image in the photosensitive element will be a positive and the image produced on the imagecarrying layer will be a negative. The expression posi tive image is intended to cover such an image produced on the image-carrying layer.

In preceding portions of the specification the expression color has been frequently used. This expression is intended to include the use of three colors to obtain black.

Throughout the specification and claims the expression superimposing has been used. This expression is intended to cover the arrangement of two layers in overlying relation to each other either in face-to-face contact or in separated condition and including between them at least one layer or stratum of a material which may be a viscous liquid.

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

What is claimed is:

1. A process of forming positive transfer images in color comprising the steps of: exposing an integral, multilayer, photosensitive monopack element comprising a support carrying a plurality of continuous, coextensive, superposed photosensitive silver halide emulsion layers, each said emulsion having associated with it a color-providing substance selected from the class consisting of an image dye and an intermediate for said image dye, each said silver halide emulsion being sensitized to different portions of the spectrum, developing each of said emulsions, immobilizing in developed areas, as a function of said development, said color-providing substance associated wit] each said emulsion thereby providing in undevelopet areas of each said emulsion an imagewise distributior of nonimmobilized, diifusible color-providing substance transferring by imbibition at least a portion of each 0: said imagewise distributions of nonimmobilized, diffusible color-providing substance to a single, superposed image receiving layer to impart thereto a plurality of dye images thereby providing a positive, multicolor image, said development and said transfer being effected by the application of a single liquid composition, wherein said colorproviding substance associated with undeveloped areas 01 at least each inner emulsion layer of said multilayer, photosensitive element is rendered diffusible only after at least substantial development of the next outer emulsion layer has occurred.

2. A process of forming positive transfer images in color as defined in claim 1 wherein said integral, multilayer, photosensitive element comprises a blue-sensitive silver halide emulsion layer, a green-sensitive silver halide emulsion layer and a red-sensitive silver halide emulsion layer, said emulsion layers being continuous, coextensive and superposed over each other and carried on a common support, said blue-sensitive silver halide emulsion layer being positioned most distant from said support and having associated therewith a yellow dye developer, said green-sensitive silver halide emulsion layer having associated therewith a magenta dye developer, and said red-sensitive sil ver halide emulsion layer having associated therewith a cyan dye developer, each of said dye developers being a compound which is, respectively, a yellow dye, a magenta dye, and a cyan dye, each said compound also being a silver halide developing agent, permeating said exposed integral, multilayer, photosensitive element with a liquid alkaline composition to solubilize said dye developers and to develop each of said emulsions, oxidizing, as a function of said development, said dye developers in exposed areas of each of said emulsions to provide an imagewise distribution of unoxidized yellow dye developer in said blue sensitive emulsion layer, an imagewise distribution of unoxidized magenta dye developer in said green-sensitive silver halide emulsion layer, and an imagewise distribution of unoxidized cyan dye developer in said red-sensitive silver halide emulsion layer, and transferring, by imbibition, at least a portion of each of said imagewise distributions of unoxidized yellow, magenta and cyan dye developers to said single image-receiving layer in superposed relationship with said exposed photosensitive element, to form said multicolor positive image.

3. A process of forming positive transfer images in color comprising the steps of: exposing an integral, multilayer, photosensitive monopack element comprising a support carrying a plurality of continuous, coextensive, superposed photosensitive silver halide emulsion layers, each said emulsion having associated with it a color-providing substance selected from the class consisting of an image dye and an intermediate for said image dye, each said silver halide emulsion being sensitized to different portions of the spectrum, developing each of said emulsions, immobilizing in developed areas, as a function of said development, said color-providing substance associated with each said emulsion thereby providing in undeveloped areas of each said emulsion an imagewise distribution of nonimmobilized, diffusible color-providing substance, transferring by imbibition at least a portion of each of said imagewise distributions of nonimmobilized, diffusible color-providing substance to a single, superposed imagereceiving layer to impart thereto a plurality of dye images, thereby providing a positive, multicolor image, said development and said transfer being effected by the application of a single liquid composition, wherein said permeation of said integral, multilayer, photosensitive element proceeds substantially layerwise, so that development of an outer emulsion layer is substantially completed and diffusion of the color-providing substance associated 23 with undeveloped areas is at least partially completed prior to substantial permeation and development of the next inner emulsion layer by said liquid composition.

4. A process of forming positive transfer images in color comprising the steps of: exposing an integral, multilayer, photosensitive monopack element comprising a support carrying a plurality of continuous, coextensive, superposed photosensitive silver halide emulsion layers, each said emulsion having associated with it a color-providing substance selected from the class consisting of an image dye and an intermediate for said image dye, each said silver halide emulsion being sensitized to different portions of the spectrum, developing each of said emulsions, immobilizing in developed areas, as a function of said development, said color-providing substance associated with each said emulsion thereby providing in undeveloped areas of each said emulsion an imagewise distribution of nonimmobilized, diffusible color-providing substance, transferring by imbibition at least a portion of each of said imagewise distributions of nonimmobilized, diffusible color-providing substance to a single, superposed image-receiving layer to impart thereto a plurality of dye images, thereby providing a positive, multicolor image, said development and said transfer being effected by the application of a single liquid composition, wherein said color-providing substances are initially insoluble in said liquid processing composition, said process including the step of rendering said nonimmobilized color-providing substances soluble in said liquid processing composition whereby they may diffuse to said image-receiving layer.

5. A photographic product comprising an integral, multilayer photosensitive monopack element comprising a support carrying a plurality of continuous, coextensive, superposed photosensitive silver halide emulsion layers and adapted to be processed wtihout separation of said layers, each of said photosensitive emulsion layers being sensitized to different portions of the spectrum and having associated therewith a color-providing substance selected from the group consisting of an image dye and an intermediate for said image dye, said color-providing substance being nondilfusible from developed areas of said emulsion and diffusible from undeveloped areas of said emulsion as a function of the development of said emulsion, an image-receiving element comprising an imagereceiving layer for receiving by diffusion transfer mobile, ditfusible color-providing substance from each of said superposed silver halide emulsion layers to provide a plurality of dye images, means interconnecting said integral, multilayer, photosensitive element for movement relative to said image-receiving element whereby said integral, multilayer, photosensitive element is positionable in superposed relation and in relatively close proximity to said image-receiving element, a rupturable container holding a liquid processing composition including a solvent for a silver halide developing agent, said container being capable of being fractured and of releasing its liquid content between said integral, multilayer, photosensitive element and said image-receiving element when said elements are brought into superposed relationship, a silver halide development agent soluble in said liquid composition positioned in one of said photosensitive elements and said liquid composition, said liquid composition being the sole liquid composition required to effect development of said silver halide emulsions after exposure thereof and to effect transfer of mobile color-providing substances from undeveloped areas of each of said emulsions to said imagereceiving layer, wherein said colorproviding substances associated with at least the inner photosensitive emulsion layers are adapted to be rendered ditfusible in said liquid composition only after at least substantial development of the next outermost photosensitive silver halide emulsion layer has occurred.

6. A photographic product as defined in claim 5, wherein said integral, multilayer photosensitive element comprises a support having superposed thereon, in sequence, a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum, and a blue-sensitive silver halide emulsion stratum, each of said emulsions being continuous and coextensive and having associated therewith, respectively, a cyan dye developer, a magenta dye developer and a yellow dye developer, each of said dye developers being a compound which is a dye of the aforesaid color, which compound is also a silver halide developing agent.

7. A photographic product as set forth in claim 5 wherein said silver halide emulsion layers of said integral, multilayer, photosensitive element are adapted to be developed sequentially by the permeation of said liquid processing composition.

References Cited UNITED STATES PATENTS Photographic Publishing (20., Boston, 1944, chapters 9 and 11 relied on, pp. 99, and 127 especially relied on.

J. TRAVIS BROWN, Primary Examiner.

PHILIP E. MANGAN, MILTON STERMAN, NOR- MAN TORCHTN, Examiners.

H. LEVINE, J. L. SPROULL, T. D. KERWIN, B. E. EDELSTEIN, G. H. BJORGE, Assistant Examiners.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,345,163 October 3, 1967 Edwin H. Land et a1.

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

Column 3, line 70, "elements" should read element Column 5, line 47, "substitutent" should read substituent Column 6, line 5, "coupers" should read couplers line 13, "other" should read others Column 9, line 47, "to", first occurrence, should read it Column 10, line 10, "or" shoul read of Column 24, line 1, "development" should read developing line 45, "2,774,668" should read 2,774,669

Signed and sealed this 24th day of February 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr. E.

Atlesting Officer Commissioner of Patents

Claims

1. A PROCESS OF FORMING POSITIVE TRANSFER IMAGES IN COLOR COMPRISING THE STEPS OF:EXPOSING AN INTEGRAL, MULTILAYER, PHOTOSENSITIVE MONOPACK ELEMENT COMPRISING A SUPPORT CARRYING A PLURALITY OF CONTINUOUS, COEXTENSIVE, SUPERPOSED PHOTOSENSITIVE SILVER HALIDE EMULSION LAYERS, EACH SAID EMULSION HAVING ASSOCIATED WIT IT A COLOR-PROVIDING SUBSTANCE SELECTED FROM THE CLASS CONSISTING OF AN IMAGE DYE AND AN INTERMEDIATE FOR SAID IMAGE DYE, EACH SAID SILVER HALIDE EMULSION BEING SENSITIZED TO DIFFERENT PORTIONS OF THE SPECTRUM, DEVELOPING EACH OF SAID EMULSIONS, IMMOBILIZING IN DEVELOPED AREAS, AS A FUNCTION OF SAID DEVELOPMENT, SAID COLOR-PROVIDING SUBSTANCE ASSOCIATED WITH EACH SAID EMULSION THEREBY PROCIDING IN UNDEVELOPED AREAS OF EACH SAID EMULSION AN IMAGEWISE DISTRIBUTION OF NONIMMOBILIZED, DIFFUSIBLE COLOR-PROVIDING SUBSTANCE, TRANSFERRING BY IMBIBITION AT LEAST A PORTION OF EACH OF SAID IMAGEWISE DISTRIBUTIONS OF NONIMMOBILIZED, DIFFUSIBLE COLOR-PROVIDING SUBSTANCE TO A SINGLE, SUPERPOSED IMAGERECEIVING LAYER TO IMPART THERTO A PLURALITY OF DYE IMAGES, THEREBY PROVIDING A POSITIVE, MULTICOLOR IMAGE, SAID DEVELOPMENT AND SAID TRANSFER BEING EFFECTED BY THE APPLICATION OF A SINGLE LIQUID COMPOSITION, WHEREIN SAID COLORPROVIDING SUBSTANCE ASSOCIATED WITH UNDEVELOPED AREAS OF AT LEAST EACH INNER EMULSION LAYER OF SAID MULTILAYER, PHOTOSENSITIVE ELEMTNT IS RENDERED DIFFUSIBLE ONLY AFTER AT LEAST SUBSTANTIAL DEVELOPMENT OF THE NEXT OUTER EMULSION LAYER HAS OCCURRED.

2. A PROCESS OF FORMING POSITIVE TRANSFER IMAGES IN COLOR AS DEFINED IN CLAIM 1 WHEREIN SAID INTEGRAL, MULTILAYER, PHOTOSENSITIVE ELEMENT COMPRISES A BLUE-SENSITIVE SILVER HALIDE EMULSION LAYER, A GREEN-SENSITIE SILVER HALIDE EMULSION LAYER AND A RED-SENSITIVE SILVER HALIDE EMULSION LAYER, SAID EMULSTION LAYERS BEING CONTINUOUS, COEXTENSIVE AND SUPERPOSED OVER EACH OTHER AND CARRIED ON A COMMON SUPPORT, SAID BLUE-SENSITIVE SILVER HALIDE EMULSION LAYER BEING POSITINED MOST DISTANT FROM SAID SUPPORT AND HAVING ASSOCIATED THEEWITH A YELLOW DYE DEVELOPER, SAID GREEN-SENSITIVE SILVER HALIDE EMULSTIO LAYER HAVING ASSOCIATED THEREWITH A MAGENTA DYE DEVELOPER, AND SAID RED-SENSITIVE SILVER HALIDE EMULSION LAYER HAVING ASSOCIATED THEREWITH A CYAN DYE DEVELOPER, EACH OF SAID DYE DEVELOPERS BEING A COMPOUND WHICH IS, RESPECTIVELY, A YELLO DYE, A MAGENTA DYE, AND A CYAN DYE, EACH SAID COMPOUND ALSO BEING A SILVER HALIDE DEVELOPING AGENT, PERMEATING SAID EXPOSED INTEGRAL, MULTILAYER, PHOTOSENSITIVE ELEMENT WITH A LIQUID ALKALINE COMPOSITION TO SOLUBILIZE SAID DYE DEVELOPERS AND TO DEVELOP EACH OF SAID EMULSIONS, OXIDIZING, AS A FUNCTION OF SAID DEVELOPMENT, SAID DYE DEVELOPERS IN EXPOSED AREAS OF EACH OF SAID EMULSIONS TO PROVIDE AN IMAGEWISE DISTRIBUTION OF UNOXIDIZED YELLOW DYE DEVELOPER IN SAID BLUE SENSITIVE EMULSION LAYER, AN IMAGEWISE DISTRIBUTIO OF UNOXIDIZED MAGENTA DYE DEVELOPER IN SAID GREEN-SENSITIVE SILVER HALIDE EMULSION LAYER, AND AN IMAGEWISE DISTRIBUTION OF UNOXIDIZED CYAN DYE DEVELOPER IN SAID RED-SENSITIVE SILVER HALIDE EMULSION LAYER, AND TRANSFERRING, BY IMBIBITION, AT LEAST A PORTION OF EACH OF SAID IMAGEWISE DISTRIBUTIONS OF UNOXIDIZED YELLOW, MAGENTA AND CYAN DYE DEVELOPERS TO SAID SINGLE IMAGE-RECEIVING LAYER IN SUPERPOSED RELATIONSHIP WITH SAID EXPOSED PHOTOSENSITIVE ELEMENT, TO FORM SAID MULTICOLOR POSITIVE IMAGE.