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Publication numberUS3787209 A
Publication typeGrant
Publication dateJan 22, 1974
Filing dateApr 24, 1972
Priority dateApr 24, 1972
Also published asCA1007089A1, DE2319470A1, DE2319470C2
Publication numberUS 3787209 A, US 3787209A, US-A-3787209, US3787209 A, US3787209A
InventorsLand E
Original AssigneePolaroid Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Color diffusion transfer color process and film with silver precipitating layer
US 3787209 A
Abstract
Diffusion transfer color processes are disclosed wherein the color image is retained with the developed silver halide emulsion(s) as part of an integral negative-positive reflection print. Provision of a silver precipitating layer between the developed silver halide emulsion layer(s) and a light-reflecting layer substantially reduces discoloration of the color transfer image highlights resulting from undesired transfer of silver ion after formation of the color image.
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Description  (OCR text may contain errors)

[ Jan. 22, 11974 COLOR DIFFUSION TRANSFER COLOR PROCESS AND FILM WITH SILVER PRECIPITATING LAYER Inventor: Edwin ll. Land, Cambridge, Mass.

Polaroid Corporation, Cambridge, Mass.

Filed: Apr. 24, 1972 Appl. No.: 246,671

Assignee:

US. Cl 96/3, 96/29 R, 96/29 D, 96176 R, 96/107 Int. Cl G03c 7/00 Field of Search ..96/3, 29 D, 77, 107, 109, 96/66.3, 61 M, 76

[56] References Cited UNITED STATES PATENTS 3,415,644 12/1968 Land ..96/3

3,647,437 3/1972 Land 96/3 Primary Examiner-4. Travis Brown Assistant ExaminerR. L. Schilling Attorney, Agent, or FirmStanley H. Mervis et al.

[57] ABSTRACT Diffusion transfer color processes are disclosed wherein the color image is retained with the developed silver halide emulsion(s) as part of an integral negative-positive reflection print. Provision of a silver precipitating layer between the developed silver halide emulsion layer(s) and a light-reflecting layer substantially reduces discoloration of the color transfer image highlights resulting from undesired transfer of silver ion after formation of the color image.

59 Claims, 2 Drawing Figures 24% TRANSPARENT SUPPORT 22+ OPAQUE LAYER I6; DEVELOPED SILVER HALIDE SILVER PRECIPITANT I47 LI 6 HT-REFLECTING LAYER IZ- C DYE IMAGE TRANSPARENT SUPPORT PATENTEDEmza 1974 3, 787, 209

mi OPAQU E S U PPORT IGtDEVELOPED SILVER HALIDE 26% SILVER PRECIPITANT I Mf LIGHT REFLECTING LAYER l2 DYE IMAGE ZOt TRANSPA RE NT SUPPORT VIEW FEST

24% TRANSPARENT SUPPORT ZZ EOPAQUE LAYER IGtDEVELOPED SILVER HA Ll DE I475 Ll G HT-REFLECTI NG LAYER IE DYE IMAGE 20+; TRANSPARENT SUPPORT VIIEW (IOLOR DIFFUSION TRANSFER COLOR PROCESS AND FILM WITH SILVER PREC if ITATEQG LAYER This invention is concerned with photography and, more particularly, with the formation of images in color by diffusion transfer processing.

A number of diffusion transfer photographic processes have been proposed wherein the resulting photograph comprises the developed silver halide emulsions retained with the dye-image carrying layer as part of a permanent laminate. The image-carrying layer is separated from thedeveloped silver halide emulsions in said laminate by a light-reflecting layer, preferably a layer containing titanium dioxide. Illustrative of patents describing such products and processes are U. S. Pat. No. 2,983,606 issued Mar. 9, 1961 to Howard G. Rogers, U. S. Pat. Nos. 3,415,644, 3,415,645 and 3,415,646 issued Dec. 10, 1968 to Edwin H. Land, U. S. Pat. Nos. 3,594,164 and 3,594,165 issued July 20, 1971 to Howard G. Rogers, and U. S. Pat. No. 3,647,347 issued Mar. 7, 1972 to Edwin H. Land.

Referring more specifically to the aforementioned U. S. Pat. No. 3,415,644, said patent discloses photographic products and processes employing dye developers wherein a photosensitive element and an imagereceiving layer are maintained in fixed relationship prior to photoexposure and this fixed relationship is maintained after processing and image formation to provide a laminate including the processed silver halide emulsions and the image-receiving layer. Photoexposure is 'made through a transparent (support) element and application of a processing composition provides a layer of light-reflecting material to provide a white background for viewing the image and to mask the developed silver halide emulsions. The desired color transfer image is viewed through said transparent support against said white background.

It has been found that such processes provide very useful and good quality images but that such images have a tendency to discolor in time.

It is therefore a primary object of this invention to provide novel diffusion transfer products and processes which provide high quality dye images as part of a permanent laminate, said dye images exhibiting good resistance to discoloration with time.

It is a further object of this invention to provide diffusion transfer color processes wherein silver halide not developed in forming the dye transfer image is reduced non-imagewise. Yet another object of this invention is to provide improved color diffusion transfer processes for forming integral negative-positive reflection prints wherein a silver halide solvent is used to improve the sensitometric properties of said print.

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

The invention accordingly comprises the product possessing the features, properties and relation of components and the process involving the several steps and the relation and order of one or more of such steps with respect to each of the others which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description of the invention taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a diagrammatic enlarged schematic illustration of a diffusion transfer dye image formed in accordance with one embodiment of this invention, and

FIG. 2 is a similar schematic illustration of a diffusion transfer dye image formed in accordance with another embodiment of this invention.

As noted above, this invention is concerned with diffusion transfer processes wherein the layer containing the diffusion transfer dye image, i.e., the imagereceiving layer, is not separated from the developed photosensitive layers after processing but both components are retained together as part of a permanent laminate. Film units particularly adapted to provide such diffusion transfer images have frequently been referred to as integral negative-positive film units. The resulting image may be referred to as an integral negativepositive reflection print and as so used is intended to refer to a reflection print wherein the developed photosensitive layers have not been separated from the image layer, i.e., the layer containing the transfer dye image. A light-reflecting layer between the developed photosensitive layer(s) and the image layer provides a white background for the dye image and masks the developed photosensitive layer(s). These layers are part of a permanent laminate which usually includes dimensionally stable outer or support layers, the transfer dye image being viewable through one of said supports. This invention is concerned with preventing or at least minimizing discoloration of the whites or highlights of such integral negative-positive reflection prints.

The present invention is applicable to a wide variety of color diffusion transfer processes and the arrangement and order of the individual layers of the film used in such color processes may vary in many ways as is known in the art, provided the final image is an integral negative-positive reflection print as described above. For convenience, however, the more specific description of the invention may be by use of dye developer diffusion transfer color processes and of integral negative-positive film units of the type contemplated in the previously mentioned U. S. Pat. No. 3,415,644.

It is known that the presence of small amounts of a silver halide solvent during development may desirably affect the sensitometric results. The addition of such silver halide solvents has been found to be useful in color diffusion transfer processes, even though a silver transfer image is neither desired nor formed. The incorporation of sodium thiosulfate or potassium thiosulfate in dye developer color transfer processes has been found to result in increased photographic sensitivity or speed.

In such integral negative-positive reflection prints, the various layers comprising the laminate tend to remain wet for a period of time much longer than the processing time, i.e., the time required simply to develop the exposed silver halide and to form the transfer image. This extended wet condition thus may permit reactions to occur which will adversely affect the color transfer image. These further reactions are most readily evidenced by changes in the highlights or whites of the color image. The incorporation within the film unit of a mechanism to reduce the pH, such as the acidic polymer layer set forth in the above-mentioned US. Pat. No. 3,415,644, has been found to greatly reduce these problems to the point where such darkening may not be evidenced until a number of days have elapsed.

It has now been found that such darkening is frequently due, at least in part, to the fact that a quantity of complexed silver does in fact transfer in a nonimagewise manner to the image-receiving layer even though said image-receiving layer is free of any silver precipitating agent, i.e., no silver precipitating agent has been included therein. This transferred silver complex is colorless or white, but subsequent photolysis or photolytic reduction is effective to reduce such complexed silver to a colored species which may be metallic silver. If the photographic laminate is exposed to appreciable quantities of light before the water within the laminate has been removed by evaporation or transpiration through the supports, sufficient complexed silver may be photolytically reduced to give an increase in the reflection density of the whites of as much as 0.3 or even more. The transfer of unreduced silver complex to the image-receiving element is believed to be a result of the inclusion within the system of a silver halide solvent, such as sodium thiosulfate, to improve the sensitometry of the process, and the continued wet" condition of the laminate.

It has now been found that the sensitometric properties of the color transfer image may be improved and the darkening substantially reduced, or even essentially eliminated, by insuring that the various reagents are substantially completely utilized during or shortly after transfer image formation. More specifically, it has been found that color transfer images having good highlights and sensitometry may be obtained using a film unit in which the photosensitive and image-receiving layers are maintained as a laminate after processing if a stratum of silver precipitating nuclei is provided, preferably between the silver halide emulsions and the lightreflecting layer. In accordance with this invention, transfer of silver to the stratum of silver precipitating nuclei and reduction to metallic silver is delayed until after the desired image dye density has been obtained. Precipitation of silver behind the light-reflecting layer insures that it will not be visible to the viewer of the color transfer image. This transfer of silver halide and reduction to silver not only insures that any silver halide which may be dissolved by the processing composition will be precipitated in a position not detrimental to transfer image quality but also provides a mechanism by which image dyes undesired in the transfer dye image may be affirmatively excluded from transfer. In addition, the more complete development of the silver halide present provides an additional consumption of alkali, thereby providing an additional pH control mechanism. The silver deposited in the silver precipitating stratum is nonimagewise.

As noted above, the addition of a silver halide solvent, such as sodium thiosulfate, in dye developer transfer processes has been taught in the art to be useful in increasing the effective film speed. Examination of image-receiving elements has shown very little, if any, silver ion to be present where the image-receiving element has been separated from the photosensitive element after transfer image formation has been completed, e.g., after about 60 seconds. It was therefore surprising to discover that complexed silver could and did later transfer to the image-receiving layer where the transfer image layer was part of a permanent laminate containing the developed silver halide emulsions. lt further was surprising to discover that a quantity of complexed silver of the order of to 40 mg. per square foot could transfer to the image-receiving layer from fully developed areas of the photosensitive silver halide emulsions, i.e., from silver halide areas which were sufficiently exposed and developed as to substantially completely prevent the transfer of image dye to the superposed areas of the image-receiving layer so that said areas of the transfer image were essentially free of dye and appear whilte.

The art has taught the use of sulfur-containing silver halide solvents, e.g., sodium or potassium thiosulfate, sodium or potassium thiocyanate. Experiments now indicate that such silver halide solvents form soluble silver complexes which are photolytically reducible. While the exact mechanism is not known, it is believed that the thio-containing silver halide solvent may decompose to provide nucleation sites for the complexed silver, thereby facilitating reduction of the complexed silver and formation of a colored species containing silver. The inclusion of an acid-reacting reagent to reduce the pH by neutralizing the alkaline system may in fact increase the susceptibility of such silver halide solvents and their silver complexes to photolytic reduction. The provision of an ultraviolet absorber is useful in reducing the severity of such photolytic darkening, but the ultraviolet absorbers most effective also absorb some visible light and therefore tend to introduce a tint or color of their own to degrade the whites of the image.

As disclosed and claimed in the copending application of Edwin H. Land, Stanley M. Bloom and Howard G. Rogers, Ser. No. 246,669 filed concurrently herewith, the use of a silver halide solvent which does not contain sulfur atoms markedly reduces darkening due to exposure to light. Particularly useful silver halide solvents are cyclic imides such as uracils. The substitution of S-methyl uracil for potassium thiosulfate, for example, has been found to reduce the D density increase by approximately percent. if a sulfur-free second silver halide complexing agent capable of forming a relatively less soluble silver complex, e.g., a 6-alkylaminopurine such as 6-benzylamino-purine, is substituted for a sulfur-containing second silver halide complexing agent such as l-phenyl-5-mercaptotetrazole, substantially all photolytic darkening can be prevented. This maintenance of white areas is effected even though analytical studies confirm that similar quantities of silver ion are still transferred to the dye image-containing layer, thus confirming the present of presence of silver ion in a form highly resistant to photolysis.

Particularly useful silver halide solvents which are free of sulfur atoms are cyclic imides such as those disclosed in U. S. Pat. No. 2,857,274, issued Oct. 21, 1958 to Edwin H. Land et al. and particularly uracils such as uracil, S-methyl uracil and 6-methyl uracil.

The present invention therefore is concerned with providing diffusion transfer color processes for forming integral negative-positive reflection prints which processes may use silver halide solvents, whether or not said solvents contain sulfur atoms, while minimizing photolytically reducible silver complex in the dye image layer. Suitable silver halide solvents include alkali metal and other thiosulfates or thiocyanates as well as the above cyclic imide silver halide solvents and other known silver halide solvents.

The silver halide solvent may be used in combination with a second silver halide complexing agent capable of forming a relatively insoluble silver salt or complex,

such as 1-phenyl-5-mercaptotetrazole and other mercaptans disclosed in the art to be useful as development restrainers. See, for example, US. Pat. No. 3,265,498 issued Aug. 9, 1966 to Howard G. Rogers and Harriet W. Lutes. A preferred group of sulfur-containing compounds of this type are the hydropyrimidine thiones disclosed in the -copending application of Stanley M. Bloom and Milton Green, Ser. No. 210,650, filed Dec. 22, 1971 as a continuation-in-part of now abandoned application ,Ser. No. 60,272, filed Aug. 30, 1970, and in the copending application of Donald 0. Rickter, Ser. No. 214,665, filed Jan. 3, I972. Particularly useful are tetrahydro-pyrimidine-2-thione and hexahydro-4, 5- trimethylenepyrimidine-Z-thione. Very useful sulfurfree compounds capable of forming a relatively less soluble complex with silver are 6-alkylamino-purines of the formula:

wherein R is an alkyl group, it being understood that alkyl is intended to include aralkyl, such as O CH:

Where the alkyl group is a simple alkyl group, better results are generally obtained when the alkyl group contains more than one or two carbons. As will be apparent from the above, the alkyl group may be substituted, e.g., by halogen, alkoxy, etc. (The use of such 6alkylamino-purines in dye developer processes is the subject of the copending application of Edwin H. Land, Stanley M. Bloom and Howard G. Rogers, Serial No. 2l l,7l8, filed Dec. 23, 1971.)

It has further been found that one may adjust the sensitometric properties of dye transfer images by varying the respective concentrations of the silver halide solvent and the second silver halide complexing agent providing a relatively insoluble silver complex.

FIGS. 1 and 2 illustrate in a simplified or schematic form the arrangement of layers in photographic films of the type with which this invention is concerned, the film or film unit being depicted as an integral laminate after processing and image formation. Since the two film units shown have many elements in common, the two figures will be described together. As will be evident from the figures, a diffusion transfer image in an image-receiving or image-carrying layer 12 is viewed through a transparent support against a lightreflecting layer 12 which in turn masks the developed I silver halide emulsion(s) 16. In FIG. 11, an opaque support 18 completes the film unit 10. The light-reflecting layer 14 preferably comprises a white pigment, particularly titanium dioxide. While only one layer 16 of silver halide emulsion is shown, it will be understood that in multicolor embodiments the silver halide emulsion layer" 16 may comprise a plurality of silver halide emulsions (blue-, greenand red-sensitive) arranged in overlying coplanar relationship or in a side-by-side or screen-like arrangement as is well known in the art. An image dye-providing material associated with each of the silver halide emulsions, in the same layer or in a contiguous layer, provides an image dye or an intermediate for an image dye having a color complementary to the light by which the associated silver halide emulsion is exposable, as is well known in subtractive color processes.

I In accordance with this invention, a layer 26 of silver precipitant is positioned between the developed silver halide emulsion l6 and the image-receiving layer 12. Soluble silver complex formed in either the exposed or unexposed areas of the silver halide emulsion 16 cannot diffuse to the image-receiving layer 12 for it will be precipitated in the silver precipitant layer 26 where it is masked by the light-reflecting layer 14.

Silver precipitating agents useful in this invention may be readily selected from among the many materials taught in the art to be useful in silver transfer processes. Examples of particularly suitable silver precipitating agents are the metallic sulfides and selenides and colloidal metals disclosed in U. S. Pat. No. 2,698,237. As will be readily apparent, suitable precautions should be taken to insure that the silver precipitating agent is confined in its own layer and is not introduced into other layers where it might adversely affect the sensitometry.

It will be understood that the elements of the film may be superposed and comprise an integral film unit during photographic exposure, i.e., photoexposure being effected throughthe transparent support 20 as shown, for example, in the aforementioned U. S. Pat. No. 3,415,644. Alternatively, the image-receiving layer 12 and its transparent support 20 may be separated from the photosensitive layers during exposure, the resulting laminate 10 being formed by the superposing of the respective elements with a processing composition containing a light-reflecting pigment distributed therebetween, as described, for example, in the aforementioned U. S. Pat. No. 2,983,606.

If the film unit is to be processed outside of a dark chamber, i.e., if it is to be removed from the camera prior to image completion and while the film is still photosensitive, appropriate opacifying reagents and/or layers should be provided. A particularly useful opacifying system for film units providing integral prints of the type shown in FIG. I and in the aforementioned U. S. Pat. No. 3,415,644 utilizes a color dischargeable reagent, preferably a pII-sensitive optical filter agent or dye, as is described in detail in U. S. Pat. No. 3,647,437 issued Mar. 7, 1972 to Edwin H. Land. In film units adapted to provide a laminate of the type shown in FIG. 2, photoexposure is effected from the side opposite the side from which the image is viewed, and an appropriate opaque layer 22 is provided over the silver halide emulsion(s) layer 116. This may be done by distributing a processing composition providing an opaque layer 22, e.g., containing carbon black, between the photosensitive layer 16 and the transparent support 24. Alternatively, opaque layer 22 may be omitted and lightprotection provided by an opaque layer (not shown) superposed over the transparent support 24 or directly over the photosensitive layer 16 after exposure.

In the preferred film structures for obtaining integral negative-positive reflection prints of the type shown in FIG. 1, photoexposure is effected through the same transparent support 20 through which the final dye transfer image is viewed.

In the preferred film units for obtaining integral negative-positive reflection prints of the type shown in FIG. 2, photoexposure is effected through the transparent support 24 and an opaque layer 22 to protect the exposed silver halide from further exposure may be provided by including a light-absorbing opacifying agent, e.g., carbon black, in the processing composition which is distributed between the photosensitive layer 16 and a transparent support 24. In such film units, it may be desirable to include a preformed opaque layer (not shown), e.g., a dispersion of carbon black in a polymer permeable to the processing composition, between a preformed light-reflecting layer 14 and the silver halide emulsion(s) 16. These embodiments are shown and described in the aforementioned U. S. Pat. Nos. 3,594,164 and 3,594,165. If desired, the silver precipitating agent may be positioned in said permeable preformed opaque layer instead of being in a separate layer.

The image dye-providing materials which may be employed in such processes generally may be characterized as either (1) initially soluble or diffusible in the processing composition but are selectively rendered non-diffusible in an imagewise pattern as a function of development; or (2) initially insoluble or non-diffusible in the processing composition but which are selectively rendered diffusible or provide a diffusible product in an imagewise pattern as a function of development. These materials may be complete dyes or dye intermediates, e.g., color couplers. The requisite differential in mobility or solubility may, for example, be obtained by a chemical action such as a redox reaction or a coupling reaction.

As examples of initially soluble or diffusible materials and their application in color diffusion transfer, mention may be made of those disclosed, for example, in U. S. Pat. Nos. 2,774,668; 2,968,554; 2,983,606; 2,087,817; 3,185,567; 3,230,082; 3,345,163; and 3,443,943. As examples of initially non-diffusible materials and their use in color transfer systems, mention may be made of the materials and systems disclosed in U. S. Pat. Nos. 3,185,567; 3,443,939; 3,443,940; 3,227,550; and 3,227,552. Both types of image-dye providing substances and film units useful therewith also are discussed in the aforementioned US. Pat. No. 3,647,437 to which reference may be made.

In any of these systems, multicolor images are obtained by employing a film unit containing at least two selectively sensitized silver halide layers each having associated therewith an image dye-providing material exhibiting desired spectral absorption characteristics. The most commonly employed elements of this type are the so-called tripack structures employing blue-, a greenand a red-sensitive silver halide layers having associated therewith, respectively, a yellow, a magenta and a cyan image dye-providing material, as disclosed in U. S. Pat. No. 3,345,163 issued Oct. 3, 1967 to Edwin H. Land and Howard G. Rogers.

A particulary useful system for forming color images by diffusion transfer is that described in U. S. Pat. No. 2,983,606, employing dye developers (dyes which are also silver halide developing agents) as the image dyeproviding materials. In such systems, a photosensitive element comprising at least one silver halide layer having a dye developer associated therewith (in the same or in an adjacent layer) is developed by applying an aqueous alkaline processing composition. Exposed and developable silver halide is developed by the dye developer which in turn becomes oxidized to provide an oxidation product which is appreciably less diffusible than the unreacted dye developer, thereby providing an imagewise distribution of diffusible dye developer in terms of unexposed areas of the silver halide layer, which imagewise distribution is then transferred, at least in part, by diffusion, to a dyeable stratum to impart thereto a positive dye transfer image. Multicolor images may be obtained with a photosensitive element having two or more selectively sensitized silver halide layers and associated dye developers, a tripack structure of the type described above in various patents including the aforementioned U. S. Pat. Nos. 2,983,606 and 3,345,163 being especially suitable for accurate color recordation of original subject matter.

In such color diffusion transfer systems, color transfer images are obtained by exposing a photosensitive element, sometimes referred to as a negative component, comprising' at least a light-sensitive layer, e.g., a gelatino silver halide emulsion layer, having an image dye-providing material associated therewith in the same or in an adjacent layer, to form a developable image; developing this exposed element with a processing composition to form an imagewise distribution of a diffusible image dye-providing material; and transferring this imagewise distribution, at least in part, by diffusion, to a superposed image-receiving layer, sometimes referred to as a positive component, comprising at least a dyeable stratum to provide a color transfer image. The negative and positive components initially may be carried on separate supports which are brought together during processing and thereafter retained together as the final integral negative-positive reflection print, or they may initially comprise a unitary structure, e.g., integral negative-positive film units wherein the negative and positive components are part of a photosensitive laminate or they may otherwise be physically retained together in superposed relationship prior to, during and after image formation. (Procedures for forming such film units wherein the positive and negative components are temporarily laminated together prior to exposure are described, for example in U. S. Pat. No. 3,652,281 to Albert J. Bachelder and Frederick J. Binda and in U. S. Pat. No. 3,652,282 to Edwin H. Land, both issued Mar. 28, 1972.) In either instance, the positive component is not removed from the negative component for viewing purposes. The preferred film units comprise a plurality of essential layers including a negative component comprising at least one light-sensitive silver halide and associated dye imageproviding material and a positive component comprising a dyeable stratum. These components may be laminated together or otherwise secured together in physical juxtaposition as an essentially integral structure. Film units intended to provide multicolor images comprise two or more selectively sensitized silver halide layers each having associated therewith an appropriate image dye-providing material providing an image dye spectral absorption characteristics substantially complementary to the light by which the associated silver halide is exposed. The most commonly employed negative components for forming multicolor images are of the tripack structure and contain blue-, greenand redsensitive silver halide layers each having associated therewith in the same or in a contiguous layer a yellow, a magenta and a cyan image dye-providing material rebe provided between the respective silver halide layers and associated image dye-providing materials or between other layers. In addition to the aforementioned essential layers, such film units further include means for providing a reflecting layer between the dyeable stratum and the negative component in order to mask effectively the silver image or images formed as a function of development of the silver halide layer or layers and also to mask image dye-providing material which is not transferred, thereby providing a background, preferably white, for viewing the color image formed in the dyeable stratum, without separation, by reflected light. This reflecting layer may comprise a preformed layer of a reflecting agent included in the film unit or the reflecting agent may be provided after photoexposure, e.g., by including the reflecting agent in the processing composition. The dye transfer image is then viewable through a dimensionally stable protective layer or support. Most preferably another dimensionally stable layer or support, which may be transparent or opaque, is positioned on the opposed surface of the essential layers so that the aforementioned essential layers are between a pair of dimensionally stable layers or support members, one of which is transparent to permit viewing therethrough of the color transfer image. A rupturable container of known description contains the requisite processing composition and is adapted upon application of pressure torelease its contents for development of the exposed film unit, e.g., by distributing the processing composition in a substantially uniform layer between a pair of predetermined layers. In film units providing an integral negative-positive reflection print of the type illustrated in FIG. 1, a processing composition containing a white pigment may be distributed between the dyeable stratum and the negative component to provide the light-reflecting layer 14.

A preferred opacification system to be contained in the processing composition to effect processing outside of a camera is that described in the above-mentioned U. S. Pat. No. 3,647,437, and comprises a dispersion of an inorganic light-reflecting pigment which also con tains at least one light-absorbing agent, i.e., optical filter agent, at a pH above the pKa of the optical filter agent in a concentration effective when the processing composition is applied, to provide a layer exhibiting optical transmission density than about 6.0 density units with respect to incident radiation actinic to the photosensitive silver halide and optical reflection density than about 1.0 density units with respect to incident visible radiation.

In lieu of having the light-reflecting pigment in the processing composition, the light-reflecting pigment used to mask the photosensitive strata and to provide the requisite background for viewing the color transfer image formed in the receiving layer may be present initially in whole or in part as a performed layer in the film unit. As an example of such a preformed layer, mention may be made of that disclosed in U. S. Pat. No. 3,615,421 issued Oct. 26, 1971 and in U. S. Pat. No. 3,620,724 issued Nov. 16, 1971, both in the name of Edwin H. Land. The reflecting agent may be generated in situ as is disclosed in U. S. Pat. Nos. 3,647,434 and 3,647,435, both issued Mar. 7, 1972 to Edwin H. Land.

The dye developers (or other image dye-providing substances) are preferably selected for their ability to with the development process. Suitable spacer or timing" layers for this purpose are described with particularity in U. S. Pat. Nos. 3,362,819; 3,419,389; provide colors that are useful in carrying out subtractive color photography, that is, the previously mentioned cyan, magenta and yellow. They may be incorporated in the respective silver halide emulsion or, in the preferred embodiment, in a separate layer behind the respective silver halide emulsion. Thus a dye developer may, for example, be in a coating or layer behind the respective silver halide emulsion and such a layer of dye developer may be applied by use of a coating solution containing the respective dye developer distributed, in a concentration calculated to give the desired coverage of dye developer per unit area, in a filmforming natural, or synthethic, polymer, for example, gelatin, polyvinyl alcohol, and the like, adapted to be permeated by the processing composition.

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

The image-receiving layer may comprise one of the materials known in the art, such as polyvinyl alcohol, gelatin, etc. It may contain agents adapted to mordant or otherwise fix the transferred image dye(s). Preferred materials comprise polyvinyl alcohol or gelatin containing a dye mordant such as poly-4-vinylpyridine, as disclosed in U. S. Pat. No. 3,148,061, issued Sept. 8, 1964 to Howard C. Haas. If the color of the transferred image dye(s) is affected by changes in pH, the pH of the image layer may be adjusted to provide a pH affording the desired color.

In the various color diffusion transfer systems which have previously been described and which employ an aqueous alkaline processing fluid, it is well known to employ an acid-reacting reagent in a layer of the film unit to lower the environmental pl-I following substantial dye transfer in order to increase the image stability and/or to adjust the pH from the first pH at which the image dyes are diffusible to a second (lower) pH at which they are not. For example, the previously mentioned U. S. Pat. No. 3,415,644 discloses systems wherein the desired pH reduction may be effected by providing a polymeric acid layer adjacent the dyeable stratum. These polymeric acids may be polymers which contain acid groups, e.g., carboxylic acid and sulfonic acid groups, which are capable of forming salts with alkali metals or with organic bases; or potentially acidyielding groups such as anhydrides or lactones. Preferably the'acid polymer contains free carboxyl groups. A1- tematively, the acid-reflecting reagent may be in a layer adjacent the silver halide most distant from the image-receiving layer, as disclosed in U. S. Pat. No. 3,573,043 issued Mar. 30, 1971 to Edwin H. Land. Another system for providing an acid-reacting reagent is disclosed in U. S. Pat. No. 3,576,625 issued Apr. 27, 1971 to Edwin H. Land.

An inert interlayer or spacer layer may be and is preferably disposed between the polymeric acid layer and the dyeable stratum in order to control or time the pH reduction so that it is not premature and interfere 3,421,893; 3,455,686; and 3,575,701.

While the acid layer and associated spacer layer are preferably contained in the positive component employed in systems wherein the dyeable stratum and photosensitive strata are contained on separate supports, e.g., between the support for the receiving element and the dyeable stratum; or associated with the dyeable stratum in those integral film units, e.g., on the side of the dyeable stratum opposed from the negative components, they may, if desired, be associated with the photosensitive strata, as is disclosed, for example, in U. S. Pat. Nos. 3,362,821 and 3,573,043. In film units such as those described in the aforementioned U. S. Pat. Nos. 3,594,164 and 3,594,165, they also may be contained on the spreader sheet employed to facilitate application of the processing fluid.

As is now well known and illustrated, for example, in the previously cited patents, the liquid processing composition referred to for effecting multicolor diffusion transfer processes comprises at least an aqueous solution of an alkaline material, for example sodium hydroxide, potassium hydroxide, and the like, and preferably possessing a pH in excess of 12, and most preferably includes a viscosity-increasing compound constituting a film-forming material of the type which, when the composition is spread and dried, forms a relatively firm and relatively stable film. The preferred film-forming materials disclosed comprise high molecular weight polymers such as polymeric, water-soluble ethers which are inert to an alkaline solution such as, for example, a hydroxyethyl cellulose or sodium carboxymethyl cellulose. Additionally, film-forming materials or thickening agents whose ability to increase viscosity is substantially unaffected if left in solution for a long period of time are so disclosed to be capable of utiliza tion. As stated, the film-forming material is preferably contained in the processing composition in such suitable quantities as to impart to the composition a viscosity in excess of 100 cps. at a temperature of approximately 24 C. and preferably in the order of 100,000 cps. to 200,000 cps. at that temperature.

This invention will be further illustrated by the following example intended to be illustrative only.

EXAMPLE A multicolor photosensitive element using, as the cyan, magenta andyellow dye developers a v I cyan:

was prepared by coating a gelatin-subcoated 4 mil. opaque polyethylene teraphthalate film base with the following layers:

1. a layer of cyan dye developer dispersed in gelatin and coated at a coverage of about mgs./ft. of dye and about 80 mgs./ft. of gelatin;

2. a red-sensitive gelatino silver iodobromide emulsion coated at a coverage of about mgs./ft. of silver and about 70 mgs./ft. of gelatin;

3. a layer of a 60-30-4-6 copolymer of butylacrylate, diacetone acrylamide, styrene and methacrylic acid and polyacrylamide coated at a coverage of about mgs./ft." of the copolymer and about 5 mgs./ft. of polyacrylamide;

4. a layer of magenta dye developer dispersed in galatin and coated at a coverage of about 1 l2 mgsJft. of dye and about 100 mgs./ft. of gelatin;

5. a green-sensitive gelatino silver iodobromide emulsion coated at a coverage of about 100 mgs./ft. of silver and about 50 mgs./ft. of gelatin;

6. a layer containing the copolymer referred to above in layer 3 and polyacrylamide coated at a coverage of about 100 mgs./ft. of copolymer and about 12 mgs./ft. of polyacrylamide;

7. a layer of yellow dye developer dispersed in gelatin and coated at a coverage of about 70 mgsJft. of dye and about 56 mgs./ft. of gelatin;

8. a blue-sensitive gelatino silver iodobromide emulsion layer including the auxiliary developer 4'- methylphenyl hydroquinone coated at a coverage of about 120 mgs./ft. of silver, about 60 rugs/ft. of gelatin and about 30 mgs/ft. of auxiliary developer; and

9. a layer of gelatin coated at a coverage of about 50 mgsJft. of gelatin.

A very thin coating of zinc sulfide in colloidal silica was applied to the surface of the photosensitive element to provide a silver precipitating layer.

A transparent 4 mil. polyethylene teraphthalate film base was coated, in succession, with the following layers to form an image-receiving component:

l. as a polymeric acid layer, the partially butyl ester of polyethylene/maleic anhydride copolymer at a coverage of about 2,500 mgs./ft.

2. a timing layer containing about a 40:1 ratio of a 60-30-4-6 copolymer of butylacrylate, diacetone acrylamide, styrene and methacrylic acid and polyacrylamide at a coverage of about 500 mgs./ft. and

3. a polymeric image-receiving layer containing a 2:1 mixture, by weight, of polyvinyl alcohol and poly-4- vinylpyridine, at a coverage of about 300 mgs/ftf. The two components thus prepared were then taped together, in laminate form, at their respective edges to provide an integral film unit, with a rupturable container retaining an aqueous alkaline processing solution fixedly mounted on the leading edge of each of the components, by pressure-sensitive tapes, so that, upon application of compressive pressure to the container to rupture the containers marginal seal, its contents were distributed in a layer approximately 0.0026 inches thick between the image-receiving layer and the gelatin overcoat layer of the photosensitive component. The aqueous alkaline processing composition comprised:

Grams Potassium hydroxide (85%) 7.24 Titanium dioxide 2].] Hydroxyethyl cellulose (Hercules Type 2.78 250M medium viscosity) Benzotriazole l. l 7 Zinc nitrate 0.29 6-methyl-5-bromo- 4-azabenzimidazole 0.59 N-benzyl-a-picolinium bromide (50% 1.17 solution in water) N-phenethyl-a-picolinium bromide 0.29 6-methy] uracil 1.2] bis-(B-aminoethyl)-sulfide 0.084 Hexahydro-4,6-trimethyl-pyrimidine-2-thione HO O C NHSO2C Ha3- H H l m l i ll.

i @0011 moox Water to make g.

The photosensitive element was exposed through the transparent support and the layers thereon, the processing composition distributed by passing the film unit between a pair of pressure-applying rolls and into a lighted area. The laminate obtained by distribution of the processing composition was maintained intact to provide an integral negative-positive reflection print which exhibited good color quality and separation. Accelerated ageing of the print showed that darkening of the highlights due to silver ion transferred to the imagereceiving layer was reduced by at least 50 percent. A similarly prepared integral negative-positive reflection print was peeled apart about 5 to 10 minutes after the processing composition was applied. A layer of black silver, substantially nonimagewise, was found to be present between the blue-sensitive silver halide emulsion of the light-reflecting titanium dioxide layer.

It will be recognized that the concentration of the silver halide solvent and of the other silver halide complexing agent(s) may be varied over a wide range. If the second silver halide complexing agent, e.g., PMT or 6 benzylaminopurine, is initially present in the imagereceiving layer, a higher concentration will be coated therein per unit area than is required if it is initially disposed in the processing composition. It should be noted that the second silver halide complexing agent may be initially present as a component of the processing composition and therefore available for permeation into the silver halide layers as soon as the processing composition is applied. This is true even of such strongly complexing mercaptans as l-phenyl-S-mercaptotetrazole which has generally been initially positioned in the image-receiving element so as to reach the silver halide only after a delay, earlier contact with the developing silver halide emulsion being taught as prematurely stopping development and permitting dye developer to be transferred to the image-receiving layer from exposed areas. While this feature. in itself is contrary to the prior general teachings, it has been found that good color separation and saturation are maintained over a wide temperature range and especially at low temperatures where it would have been expected that the presence of such mercaptans in the processing composition would reduce the control of dye transfer. The use of the preferred 6-alkylaminopurines gives especially good sensitometric results in dye developer transfer processes over a very wide temperature range. Thus, it has been found that a given concentration of 6- benzylamino-purine will give good sensitometric results over a broader temperature range than will a given concentration of a mercaptan such as PMT.

It will be understood that dye transfer images which are neutral or black-and-white instead of multicolor may be obtained by use of a mixture of dyes of the appropriate colors, the transfer of which may be controlled by a single layer of silver halide, in accordance with known techniques. It is also to be understood that direct positive" silver halide emulsions may also be used, depending upon the particular dye imageproviding substances employed and whether a positive or negative color transfer image is desired.

It will be recognized that in the use of certain image dye-providing materials, the precipitation of silver by the silver precipitating agent could give rise to a reaction product, e.g., an oxidized developing agent, which could react with said image dye-providing material to generate a diffusible image dye or image dye intermediate. Such unwanted dye density in the transfer image may be avoided by positioning a scavenger for such reaction product intermediate the silver precipitating layer and the image dye-providing material. Thus, if the reaction product were an oxidized developing agent, a nondiffusible reducing agent positioned between the silver precipitating layer and the image dye-providing material could be used to reduce the oxidized developing agent before it could enter into the dye release reaction.

in those embodiments wherein the process is performed outside of a dark chamber, the layer of silver deposited in the silver precipitating layer may assist in providing the requisite opacification. In particular, the opacification provided by the layer of silver thus created may permit discharging the color of an optical filter at a more rapid rate. It is within the scope of this invention to employ as one or both of the support layers polymeric or other materials which transmit water vapor at a rate adapted to dry the laminate rapidly. Suitable supports of this type are described, for example, in U. S. Pat. No. 3,573,044 issued Mar. 30, 1971 to Edwin H. Land.

It will be seen from the above that this invention provides a marked reduction in the tendency of diffusion transfer integral negative-positive color reflection prints to exhibit discoloration of the highlights from photolytic degradation of unreduced silver ion present in the dye image layer.

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

What is claimed is:

l. A photographic product for forming a diffusion transfer image in dye within a permanent laminate including at least one developed silver halide layer, said photographic product comprising, in combination, an image-receiving layer; at least one silver halide emulsion, each said silver halide emulsion having associated therewith an image dye-providing substance selected from the group consisting of image dyes and image dye intermediates; means providing a light-reflecting layer between said image-receiving layer and said silver halide emulsion(s) to mask said silver halide emulsion(s) after development thereof and to provide a white background for viewing a dye image in said image-receiving layer; a transparent support through which imagereceiving layer may be viewed; a rupturable container releasably retaining a processing composition for developing said silver halide emulsion(s) after photoexposure and for forming a transfer image in at least one dye in said image-receiving layer; said product including a silver halide solvent capable of forming a soluble silver complex and means providing a silver precipitating layer including a silver precipitating agent adapted to precipitate soluble silver complex, said silver precipitating layer being positioned on the same side of said light-reflecting layer as said silver halide emulsion(s) whereby silver precipitated in said silver precipitating layer is masked by said light-reflecting layer.

2. A photographic product as defined in claim 1 wherein each said image dye-providing substance is a dye. I

3. A photographic product as defined in claim 2 wherein each said dye is a dye developer.

4. A photographic product as defined in claim 1 wherein each said image dye-providing substance is an intermediate for an image dye.

5. A photographic product as defined in claim 1 wherein said silver halide emulsions are a red-sensitive silver halide emulsion, a green-sensitive silver halide emulsion and a blue-sensitive silver halide emulsion, and said silver halide emulsions have associated therewith, respectively, a cyan image dye-providing substance, a magenta image dye-providing substance and a yellow image dye-providing substance.

6. A photographic product as defined in claim 1 wherein said silver halide emulsion(s) are adapted to be exposed through said transparent support.

7. A photographic product as defined in claim 1 wherein said silver precipitating layer is positioned between said silver halide emulsion(s) and said lightreflecting layer.

8. A photographic product as defined in claim 1 wherein said silver halide solvent is an alkali metal thiosulfate.

9. A photographic product as defined in claim 1 wherein said silver halide solvent is a uracil.

10. A photographic product as defined in claim 1 wherein said means providing a light-reflecting layer comprise a white pigment dispersed in said processing composition, said rupturable container being positioned to distribute said processing composition containing said pigment between said image-receiving layer and said silver halide emulsion(s).

11. A photographic product as defined in claim 1, including a second silver halide complexing agent, said second silver halide complexing agent being capable of forming a less soluble complex with silver halide than said silver halide solvent.

12. A photographic product as defined in claim 8 wherein said second silver halide complexing agent contains a mercapto group or a group which provides a mercapto group during processing.

13. A photographic product as defined in claim 11 wherein said second silver halide complexing agent contains no sulfur atoms.

14. A photographic product as defined in claim 1 comprising a temporary laminate including said layers confined between two dimensionally stable supports, at least one of said supports being transparent, the bond between a predetermined pair of layers being weaker than the bond between other pairs of layers, said rupturable container being so positioned as to distribute said processing composition between said predetermined layers, said processing composition being adpated to provide said permanent laminate following distribution and drying.

15. A photographic product as defined in claim 1 wherein said transparent support is polyester.

16. A photographic product as defined in claim wherein said polyester is polyethylene terephthalate.

17. A photographic product as defined in claim 1 wherein said transparent support is cellulose acetate.

13. A photographic product comprising a first support; a red-sensitive silver halide emulsion; a greensensitive silver halide emulsion; and a blue-sensitive silver halide emulsion; said silver halide emulsions having associated therewith, respectively, a cyan dye developer, a magenta dye developer and a yellow dye developer; an image-receiving layer for receiving image dyes transferred thereto by diffusion as a function of exposure and development of said silver halide emulsion layers; a second support which is transparent and through which said image-receiving layer may be viewed; a rupturable container releasably holding a processing composition adapted, upon distribution between predetermined layers of said film to develop said silver halide emulsions and to effect the formation of a transfer image in dye in said image-receiving layer, said processing composition also being adapted to provide a permanentlaminate including said developed silver halide emulsions and said image-receiving layer; and means providing a light-reflecting layer between said image-receiving layer and said silver halide emulsions effective to provide a white background for viewing said transfer image and for masking said developed silver halide emulsions; said product including a silver halide solvent capable of forming a soluble silvercomplex, and a layer of silver precipitating agent positioned between said silver halide emulsion layers and said light-reflecting layer.

19. A photographic product as defined in claim 18 wherein said means for providing a light-reflecting layer comprises a preformed layer of a white pigment.

20. A photographic product as defined in claim 18 wherein said means for providing a light-reflecting layer comprises a white pigment dispersed in said processing composition.

21. A photographic product as defined in claim 18 wherein said first support is opaque.

22. A photographic product as defined in claim 13 wherein said transparent support is a polyester.

23. A photographic product as defined in claim 22 wherein said polyester is polyethylene teraphthalate.

24. A photographic product as defined in claim 23 wherein said opaque support is polyethylene teraphthalate.

25. A photographic product as defined in claim 18 wherein said transparent support is cellulose acetate.

26. A photographic product as defined in claim 18 wherein said silver halide solvent is a cyclic imide.

27. A photographic product as defined in claim 26 wherein said silver halide solvent is a uracil.

2%. A photographic product as defined in claim 27 wherein said uracil is fi-methyl uracil.

29. A photographic product as defined in claim 18 wherein said silver halide solvent is a component of said processing composition.

30. A photographic product as defined in claim 13 wherein said silver halide solvent is an alkali metal thiousulfate.

31. A photographic product as defined in claim 30 wherein said silver halide solvent is potassium thiosulfate.

32. A photographic product as defined in claim 18 wherein said product includes a second silver halide complexing agent, said second silver halide complexing agent being capable of forming a less soluble complex with silver halide than said silver halide solvent.

33. A photographic product as defined in claim 32 wherein said second silver halide complexing agent contains a mercapto group or a group which provides a mercapto group during processing.

34. A photographic product as defined in claim 33 wherein said second silver halide complexing agent is a mercaptotetrazole.

35. A photographic reagent as defined in claim 33 wherein said secondsilver halide complexing agent is a mercapto-substituted tetrahydropyrimidine.

36. A photographic product as defined in claim 32 wherein said second silver halide complexing agent contains no sulfur atoms.

37. A photographic product as defined in claim 36 wherein said second silver halide complexing agent is a 6-alkylamino-purine.

38. A photographic product as defined in claim 37 wherein said 6-alkylamino-purine is 6-benzylaminopurine.

39. A photographic product as defined in claim 18 wherein said product includes a uracil.

40. A photographic product as defined in claim 18 wherein said transparent support and said imagereceiving layer comprise a separate element adapted to be brought into superposed relationship with said silver halide emulsions.

41. A photographic product as defined in claim 18 wherein said layers are held in fixed relationship between said supports prior to and during exposure.

42. A photographic product as defined in claim 41 wherein said fixed relationship is provided by binder tape along at least two parallel sides of said product.

43. A photographic product as defined in claim 41 wherein said product is a laminate of said layers between said first and said second supports, the bond between a pair of predetermined layers being weaker than the bonds between the other layers, said rupturable container being so positioned as to release said processing composition for distribution between said pair of layers.

44. A photographic product as defined in claim 13 wherein said silver halide emulsions are present as separate planar layers.

45. A photographic product as defined in claim 18 wherein said silver halide emulsions are present in the form of minute elements arranged in side-by-side relationship in a photosensitive screen pattern.

46. A photographic product as defined in claim 44 wherein said blue-sensitive silver halide emulsion layer is between said image-receiving layer and said other silver halide emulsion layers.

47. A photographic product as defined in claim 44 wherein said blue-sensitive silver halide emulsion layer is between said first support and said other silver halide emulsion layers, and said first support is transparent.

48. A photographic product as defined in claim 18 including means to reduce the pH of a layer of said processing composition from a first pH to a second pH.

49. A photographic product as defined in claim 48 wherein said means to reduce the pH comprises a layer of an acid-reacting reagent positioned between said transparent support and said image-receiving layer.

50. A photographic product as defined in claim 49 wherein said acid-reacting reagent is a polymer.

51. A photographic product as defined in claim 18 wherein said processing composition includes an optical filter agent which is colored at the pH of said processing composition, said optical filter agent being adapted to be rendered colorless by reducing said pH.

52. In a method of forming a diffusion transfer dye image by developing an exposed silver halide emulsion in the presence of a silver halide solvent, forming a imagewise distribution of a diffusible dye image-providing substance as a function of said development, and transferring at least a portion of said imagewise distribution of diffusible dye image-providing substance to an image-receiving layer in superposed relationship with said silver halide emulsion to provide said dye image, said image-receiving layer and said silver halide emulsion forming a permanent laminate including a lightreflecting layer positioned between said imagereceiving layer and said silver halide emulsion, the improvement wherein soluble silver complex capable of diffusing to said image-receiving layer is precipitated in a layer between said silver halide emulsion and said light-reflecting layer.

53. The method defined in claim 52 wherein said silver halide solvent is a cyclic imide.

54. The method as defined in claim 52 wherein said silver halide solvent is a thiosulfate.

S5. The method as defined in claim 52 wherein said development and transfer are eflected in the presence of a silver halide complexing agent which forms an insoluble silver complex.

56. The method as defined in claim 52 wherein said diffusible dye image-providing substance is a dye developer.

57. The method as defined in claim 51 wherein a redsensitive silver halide emulsion, a green-sensitive silver halide emulsion and a blue-sensitive silver halide emulsion are present, said silver halide emulsions having associated therewith, respectively, a cyan dye developer,

a magenta dye developer and a yellow dye developer, and said dye image is a multicolor image.

58. A photographic product comprising a support carrying a red-sensitive silver halide emulsion layer, a green-sensitive silver halide emulsion layer, and a bluesensitive silver halide emulsion layer, said red-sensitive silver halide emulsion having associated therewith a cyan image dye-providing substance, said greensensitive silver halide emulsion having associated therewith a magenta image dye-providing substance, and said blue-sensitive silver halide emulsion having associated therewith a yellow image dye-providing substance, each said image dye-providing substance being selected from the group consisting of image dyes and image dye intermediates, the outermost said silver halide emulsion layer carried by said support carrying a silver precipitating layer including a silver precipitating agent.

59. A photographic product as defined in claim 58 wherein said image dye-providing substances are, respectively, a cyan dye developer, a magenta dye developer and a yellow dye developer.

k m a n:

PatentNo. 3,787,2 09- Da ted' January 2;. 1974 Inventofls) I Edwin H. Land It is certified that error appears in the above-identified patent and that said Letters Patentere hereby corrected as shown below:

Column 4, line 8, "whilte" should be -white.

j Column 5, line 38, "6alkylamino" should be -6alkylamino.

' Column 9, line 57, "performed" should be preformed-m Column 9, delete lines 67 and 68..

Column 10, delete lihe l. Column l l,,'.'be fo re line 1, insert -with the development process. Suitable spacer or "timing" layers for this purpose are described with particularity in U. 8. Patents Nos.

Column 12,- line 45,- "teraphthalate" should be -terephtha .late--.

Column 12, line 58, "gelatin" should be --ge1a-tin- Column .13, line 14, "teraphthalate" should be '---terephthalate---.

I Column line 51 "teraphthalate" should be --terephthalate--.

Column 17, line; 66, "thiousulfa'te" should be -'-thiosulfate-- Signedand sea led this 19th day of November 1974.

V'(SEAL) 1 Attest:

' McCOY M. GIBSON JR. c MARSHALL DANN Attestgng Officer Commissioner of Patents 'OFiM 5 0-1050 (10-69) uscouM-oc bean-Pas \l.$. GOVIIIIIMINY VRIIITING OPTIC! 1 I90 O-!lO-Sll

Patent Citations
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US3415644 *Mar 10, 1967Dec 10, 1968Polaroid CorpNovel photographic products and processes
US3647437 *Dec 18, 1970Mar 7, 1972Polaroid CorpPhotographic products, processes and compositions
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3933494 *Nov 8, 1973Jan 20, 1976Minnesota Mining And Manufacturing CompanyMethod for obtaining a color contrast photographic image by color development and silver salt diffusion transfer processing of one photographic element
US4102685 *Aug 26, 1976Jul 25, 1978Polaroid CorporationPhotographic uses of polyvinylphenylmercapto-tetrazole:multivalent metal cation combinations
US4134768 *Apr 1, 1977Jan 16, 1979Polaroid CorporationPhotographic uses of polyvinyl-phenylmercapto-tetrazoles
US4820608 *Oct 21, 1987Apr 11, 1989Agfa-Gevaert, N.V.Dye diffusion transfer imaging process and image receptor used therein
US5543258 *Jun 22, 1994Aug 6, 1996Fuji Photo Film Co., Ltd.Photoconductive material on paper support comprising zinc oxide and a resin binder
Classifications
U.S. Classification430/214, 430/218
International ClassificationG03C8/08, G03C8/16, G03C8/48, G03C8/02, G03C8/00
Cooperative ClassificationG03C8/16
European ClassificationG03C8/16