US3756816A

US3756816A - Orming polymer dispersion photographic film units including a layer comprising an aqueous filmf

Info

Publication number: US3756816A
Application number: US00209229A
Authority: US
Inventors: C Sullivan
Original assignee: Polaroid Corp
Current assignee: Polaroid Corp
Priority date: 1971-12-17
Filing date: 1971-12-17
Publication date: 1973-09-04
Anticipated expiration: 1990-09-04

Abstract

COATING COMPOSITIONS FOR PREPARING AN INTERLAYER BETWEEN TWO SILVER HALIDE LAYERS EACH OF WHICH HAS A DYE IMAGE-PROVIDING MATERIAL ASSOCIATED THEREWITH IN A FILM UNIT FOR PREPARING COLOR IMAGES; AND FILM UNITS INCLUDING AT LEAST ONE SUCH INTERLAYER, WHEREIN THE COATING COMPOSITION INCLUDES A DYE IMPERMEABLE COALESCED ESSENCE OF AN AQUEOUS FILM-FORMING POLYMER DISPERSION AND A PROCESSING COMPOSITION PERMEABLE MATERIAL ASSOCIATED THEREWITH AND ADAPTED TO RENDER THE INTERLAYER FORMED THEREFROM PERMEABLE TO SOLUBILIZED DYE IMAGE-FORMING MATERIAL SUBSEQUENT TO BEING CONTACTED WITH THE PROCESSING COMPOSITION EMPLOYED TO DEVELOP THE FILM UNIT, AND WHEREIN THE COALSCED ESSENCE MATERIAL HAS A MEAN PARTICLE SIZE OF FROM ABOUT 0.095U TO ABOUT 0.115U.

Description

p 4, 1973 c. I. SULLIVAN 3,756,816

PHOTOGRAPHIC FILM UNITS INCLUDING A LAYER CO RISING AN AQUEOUS FIL MFORMING POLYMER DISPERS Filed Dec. 17, 1971 /CYAN DYE DEVELOPER LAYER a RED-SENSlTIVE SILVER HALIDE EMULSION LAYER |5- \JINTERLAYER l6- L/MAGENTA DYE DEVELOPER LAYER |7- GREEN-SENSITIVE SILVER HALIDE EMULSION LAYER I84 flNTERLAYER fYELLOW DYE DEVELOPER LAYER REE-SENSITIVE SILVER HALIDE EMULSION LAYER PAUXILIARY LAYER IMAGERECEIVING LAYER /SPACER LAYER ./-NEUTRALIZING LAYER SUPPORT United States Patent O 3,756,816 PHOTOGRAPHIC FILM UNITS INCLUDING A LAYER COMPRISING AN AQUEOUS FILM- FORMING POLYMER DISPERSION Charles I. Sullivan, Melrose, Mass., assignor to Polaroid Corporation, Cambridge, Mass. Filed Dec. 17, 1971, Ser. No. 209,229 Int. Cl. G03c 7/00, /54 US. Cl. 96-3 21 Claims ABSTRACT OF THE DISCLOSURE Coating compositions for preparing an interlayer between two silver halide layers each of which has a dye image-providing material associated therewith in a film unit for preparing color images; and film units including at least one such interlayer, wherein the coating composition includes a dye impermeable coalesced essence of an aqueous film-forming polymer dispersion and a processing composition permeable material associated therewith and adapted to render the interlayer formed therefrom permeable to solubilized dye image-forming material subsequent to being contacted with the processing composition employed to develop the film unit, and wherein the coalesced essence material has a mean particle size of from about 0.095 1. to about 0.l15,u..

BACKGROUND OF THE INVENTION Film units for use in preparing color images including at least two selectively sensitized silver halide emulsion layers each having a dye image-providing material associated therewith are per se well known in the art. It is also well known to employ an interlayer between each set of silver halide layers and associated dye image-providing material. Such interlayers may be referred to simply as negative interlayers. Most commonly, such film units for use in preparing multicolor images are of the so-called tripack configuration including a red-sensitive, a green-sensitive and a blue-sensitive silver halide emulsion layer having associated therewith, respectively, a cyan, a magenta and a yellow dye image-providing ma terial. An interlayer is typically disposed between the first and second emulsion sets and between the second and third emulsion sets.

Film units of this type may be employed in accordance with various diffusion transfer systems for forming color images. Generally speaking, in such diffusion transfer systems, the photosensitive strata are exposed to form a developable image, the thus exposed unit is contacted with a developing composition to develop the image and to form, as a function of this development, an imagewise distribution of dye image-providing material which is then transferred, at least in part, by diffusion, to a dyeable stratum to impart thereto the desired color transfer image. The dyeable stratum may be contained on a separate (image-receiving) element, i.e., an element separate from the photosensitive element, or the aforementioned layers may be contained as a single element, e.g., on a single support member or confined between a pair of support members, as a unitary film unit. As examples of such unitary film units, mentioned may be made of the integral negative-positive film units described and claimed in US. Pat. Nos. 3,415,644; 3,415,645; 3,415,646; 3,473,- 925; 3,573,042; 3,573,043; 3,573,044; 3,576,625; 3,576,- 626; 3,578,540; 3,579,333; 3,594,164; 3,594,165 and others.

The dye image-providing materials which may be employed in such processes generally may be characterized as either (1) initially soluble or difiusible in the processing composition but are selectively rendered non-diifusible in an imagewise pattern as a function of development; or

Patented Sept. 4, 1973 (2) initially insoluble or non-diifusible in the processing composition but which are selectively rendered dilfusible in an imagewise pattern as a function of development. These materials may be complete dyes or dye intermediates, e.g., color couplers.

As examples of initially soluble or dilfusible materials and their application in color dilfusion transfer, mention may be made of those disclosed, for example, in US. Pats. Nos. 2,647,049; 2,661,293; 2,698,244; 2,698,- 798; 2,802,735; 2,774,668; and 2,983,606. As examples of initially non-ditfusible materials and their use in color transfer systems, mention may be made of the materials and systems disclosed in US. Pats. Nos. 3,443,939; 3,443,- 940; 3,227,550; 3,277,551; 3,227,552; 3,227,554; 3,243,- 294- and 3,445,228.

A particularly useful system for forming color images by diffusion transfer is that described in US. Pat. No. 2,983,606, employing dye developers (dyes which are also silver halide developing agents) as the dye image-providing 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 ditfusible 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 postive 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 and in various patents including the aforementioned US. Pat. No. 2,983,606 being especially suitable for accurate color recordation of the original subject matter.

The copending application of Avtges et al., Ser. No. 119,331, filed Feb. 26, 1971, and now US. Pat. No. 3,625,685, describes and claims negative interlayers for use in the foregoing film units comprising a dye impermeable coalesced essence of an aqueous film-forming poymer dispersion and a processing composition permeable material associated therewith and adapted to render said layer permeable to solubilized dye image-forming material subsequent to being contacted with processing composition.

It is to film units employing negative interlayers of the foregoing description that this invention is directed.

SUMMARY OF THE INVENTION In accordance with this invention, the coalesced essence polymer employed in the preparation of the negative interlayer will possess a mean particle size of from about 0.095 to 0.115 as will be discussed in more detail hereinafter.

BRIEF DESCRIPTION OF THE DRAWING The figure is an enlarged, fragmentary, diagrammatic, sectional view of a film unit contemplated by this invention.

DESCRIPTION OF PREFERRED EMBODIMENT In the preferred embodiment, the film unit will include a layer of a cyan dye developer, a red-sensitive gelatino silver iodobromide emulsion layer, a first interlayer as described previously, a layer of a magenta dye developer, a green-sensitive gelatino silver iodobromide emulsion layer, a second interlayer as described previously, a layer of a yellow dye developer, and a blue-sensitive silver iodobromide emulsion layer. While the foregoing may comprise the essential layers of a photosensitive element to be used in systems for forming a color transfer image on a separate image-receiving element including a dyeable stratum, e.g., as shown in FIG. 9 of the aforementioned U.S. Pat. No. 2,983,606, the most preferred film units contemplated by this invention are those integral negative-positive film units of the types disclosed in the aforementioned patents wherein these essential layers comprise the negative component and the film unit further includes a positive component containing at least the dyeable stratum.

The present invention is directed to color film units, particularly multicolor film units for use in preparaing reproductions in eolor'of the original subject matter, which film units include at least one negative interlayer of the type described and claimed in the aforementioned U.S. Pat. No. 3,625,685.

As is stated in this copending application, if one or more of the interlayers is specifically selected to comprise the coalesced essence of a latex comprising a synthetic polymer (hereinafter referred to in the present application as latex) as a continuous phase, and a material which provides predetermined image-forming dye permeation characteristics to the coalesced latex and is compatible therewith (hereinafter referred to in the present application as permeator) as a discontinuous phase, interimage effects are minimized and color purity is maximized. The essence of that invention therefore resides in the utilization of a photosensitive element comprising at least two selectively sensitized silver halide strata separated by an interlayer comprising the coalesced essence of an aqueous film-forming synthetic polymer dispersion, as a continuous phase, and a material compatible therewith, as a discontinuous phase, characterized in that said compatible material is permeable to, and said coalesced dispersion is either permeable or impermeable to, but preferably permeable to, various photographic-associated materials such as water molecules, hydroxyl ions, antifoggant molecules and various other adjuncts generally contained in diifusion transfer photographic processing compositions; and, subsequent to contact of said interlayers with said processing composition, said interlayer is rendered permeable to processing composition solubilized dye image-forming material by reason of said compatible material being rendered image-forming dye permeable.

In the foregoing description, the latex portion has been denoted as the continuous phase; while the permeator portion has been denoted as the discontinuous phase. Such terminology is considered to connote an admixture of the two components with the former component being present in greater concentration than the latterwhich may be present in the form of continuous channels, etc. throughout the coalesced latex. The interlayer may also be regarded as comprising a plurality of layers of dye-impermeable latex particles of a given particle size with the interstices of the interlayer containing the dye-permeable permeator. I

Among the various latex materials which have been found to impart the requisite functionality to the herein considered systems are latices of polyvinylidene chloride, lightly carboxylated styrene butadiene copolymers, polyvinyl chloride, vinyl chloride-vinyl acetate copolymers, acrylic polymers and copolymers as, for example, a terpolymer of butylacrylate, methylmethacrylate and small amounts of acrylic acid or methacrylic acid, and innumerable other latices which will readily come to mind to one of ordinary skill in polymer chemistry. An extensive compilation of appropriate latices which may be utilized herein will be found in U.S. Pat. No. 2,795,564. The latex component of the system comprising the present invention may be chosen so that the coalescedfilm produced therewith provides a desired hydroxide ion permeability when cast into a film. Preferred latex materials comprise a 60-38-2 copolymer of methylmethacrylate, butylacrylate and acrylic acid, respectively; a 60-30-4-6 copolymer of butyacrylate, diacetone acrylamide, styrene and methacrylic acid, respectively; and a 603046-l.5-0.5 copolymer of butylacrylate, diacetone, acrylamide, styrene, methacrylic acid, 2-sulfoethyl methacrylate and divinyl benzene, respectively, all proportion designations being on a by weight basis unless otherwise denoted.

As examples of useful permeators disclosed in U.S. Pat. No. 3,625,685, mention may be made of isopropyl cellulose, preferably containing about 1.3 isopropyl groups per cellulosic monomer unit, hydroxypropyl cellulose, acrylonitrile acrylic acid copolymers, methylacrylate acrylic acid copolymers, preferably containing about 3% by weight acrylic acid, poly-N-ethyl acrylamide, polyacrylamide, polyethylene oxide, terpolymers of N-ethylacrylamide, methacrylamide and acrylamide, copolymers of N-ethylacrylamide and 2-vinyl pyridine, copolymers of N-isopropyl acrylamide and N-vinyl pyrrolidone, copolymers of N-isopropyl acrylamide and dimethylaminoethyl acrylate, etc. As is disclosed in U.S. Pat. No. 3,421,892, many of the above-denoted materials have been found to provide an increase in temperature latitude in various diffusion transfer photographic systems in that the rate at which the permeation induction propensities of such materials are activated after contact with processing composition comprises an inverse function of temperature so that, with increasing temperature, the permeation characteristics of the material diminish, while with decreasing temperature, an increase in permeation propensities is accomplished.

Among other materials which may be utilized as dye permeation-inducing compositions are graft copolymers, particularly on a polyvinyl alcohol backbone, as, for example, those disclosed in U.S. Pat. No. 3,575,700.

The essence of the present invention is the discovery that the particle size of the latex in the interlayer has an important effect upon the efficiency of its function. If the latex particle size is too great, the permeator-filled interstices are in turn too large and the layer is therefore too loose, permitting some back-diffusion of dye and the resulting interimage effects. On the other hand, if the latex particle size is too small, the interstices are also too small and the layer is too tight, impeding dye transfer therethrough.

In accordance with the present invention it has been discovered that the particle size of substantially all of the latex particles in the interlayer should be from about 0095 to about 0.115 to achieve optimum efficiency of the interlayer.

The particle size of the latex may be controlled to a predetermined desired particle size during its manufacture simply by regulating the amount of emulsifier employed in the synthesis of the latex. The greater the amount of emulsifier employed, the finer the particle size; and, conversely, with lesser amounts, coarser particles are obtained. In the following illustrative synthesis, latex particles within the range contemplated by this invention were obtained by employing 0.5 :0.2 of emulsifier to 100 parts of monomer mix.

Preparation of a 60-3046 copolymer of butylacrylate,

diacetone acrylamide, styrene and methacrylic acid To a reactor containing 1700 g. of deionized Water add 11.52 g. of a 45% solution of Dowfax 2A1 (trademark of Dow Chemical Co. for an emulsifier, sodium dodecyl diphenylether disulfonate). Adjust the temperature of the reactor to about C. In a separate container add 621.6 g. of butylacrylate, 38.52 g. of styrene and 64.35 g. of methacrylic acid while agitating. Then add 310.8 g. of diacetone acrylamide. When the diacetone acrylamide is almost dissolved (approximately 15 minutes), add 16.77 g. of deionized water while continuing mixing. Add about 15% (158.0 g.) of this mixture to the reactor slowly while using moderate agitation and while maintaining the temperature at about 75 C. Mix for about minutes and then add about 44.26 g. of an initiator solution prepared by dissolving 4.11 g. of potassium persulfate in 130.0 g. of deionized water. Whenthe reaction has peaked, add the remaining 85% of the monomer mix at about 9.9 g./min. while maintaining the temperature between about 78-83 C. About 30 minutes after beginning the addition of the rest of the monomer, start adding 88.51 g. of the above-mentioned initiator and continue at a rate of about .98 g./min. About 30 minutes after completing this step, add a solution of 0.40 g. of tertiary butyl hydroperoxide and 0.22 g. of 45% Dowfax 2A1 in 2.24 g. of deionized water and mix well. Then add a solution of 0.40 g. of ascorbic acid in 43.4 g. of deionized water while mixing well. Hold the temperature of the mixture at about 78-83" C. for about 2 hours more to provide an emulsion of the above-mentioned copolymer of butylacrylate, diacetone acrylamide, styrene and methacrylic acid.

While the latex prepared above may be employed in the preparation of the interlayer coating solutions to which this invention is directed, it is preferred that the pH first be adjusted from the initial acidic pH which may be on the order of about 2.2 to a more neutral pH, e.g., a pH on the order of from about 6.0 to about 8.5. While there does not appear to be any sensitometric advantages in this neutralizing step and the latex may therefore be employed as prepared above and without being neutralized, it has been found that neutralizing enhances the stability of the latex polymer during the handling and coating operations. For example, the neutralized latex has a much higher shear and can stand more abuse with the pumps and other equipment employed in the handling and coating steps. Moreover, since the adjacent layers in the film unit typically have a pH on the order of about 5.5 to 6, as compared to a pH of around 2.2 for the non-neutralized latex, the more acidic latex coating has a tendency to be a shock to the film unit, causing reduced stability at the interfaces if the latex pH is too low, causing coascervation or some other irregularity.

This neutralization may be obtained by adding a suitable base, e.g., an ammonium hydroxide solution, to the emulsion prepared above. If desired, bases having a quantitatively traceable cation may be employed as a tagging means for quantitative analysis of the interlayer. As an example of such a base, mention may be made of rubidium hydroxide, cesium hydroxide and the like.

The coating solution for preparing the negative interlayer may be obtained simply by adding an aqueous solution of the permeator to the latex emulsion to provide the latex/permeator coating solution containing the appropriate ratios of ingredients. This solution may then be coated as a layer in the film unit by standard coating techniques to provide the negative interlayer at the desired coverage.

As was mentioned previously, the negative interlayers of this invention may be employed in photosensitive elements including at least two sets of silver halide layers each having a dye image-providing material, e.g., a dye developer, associated therewith. An illustrative photosensitive element of this description includes, in order, a layer of a cyan image-providing material, a red-sensitive silver halide layer, an interlayer, a layer of a magenta image-providing material, a green-sensitive silver halide layer, an interlayer, a layer of a yellow image-providing material and a blue-sensitive silver halide layer. The photosensitive element may also contain additional layers performing specific desired functions. In any event, the aforementioned layers are usually contained on a suitable support member which may be opaque or transparent. This photosensitive element may be employed in any of the known subtractive or additive color systems. A particularly useful system is diffusion transfer wherein the photosensitive element is used in conjunction with a second or image-receiving element including at least a dyeable stratum. In such systems, the photosensitive element is exposed and then developed to provide, as a function of this development, an imagewise distribution of a dye image-providing material which is transferred, at least in part, by diffusion, to the superposed receiving element to impart thereto a color transfer image. The respective elements may be retained together or they may be separated following image formation to provide the desired color image.

The preferred film units contemplated by this invention are so-called integral negative-positive film units having a negative component including at least two sets of silver halide layers each having a dye image-providing material associated therewith, i.e., a component containing the various layers mentioned above in the description of a photosensitive element contemplated by this invention; and a positive component including at least a dyeable stratum, particularly such film units as are described and claimed in the illustrative patents pertaining thereto which were mentioned in the Background of the Invention and which may be employed to obtain a color transfer image viewable without separation as a reflection print. In addition to the aforementioned layers, such film units preferably also contain an acid-reducing or neutralizing layer, e.g., a polymeric acid layer of the type described in U.S. Pat. No. 3,362,819. This neutralizing layer is preferably contained in the positive component on the side of the dyeable stratum opposed from the negative component and most preferably a spacer layer is disposed between the dyeable stratum and this neutralizing layer. Suitable spacer layers are described in the aforementioned U.S. Pat. No. 3,362,819 and in U.S. Pat. Nos. 3,421,893; 3,455,686; 3,575,701 and others.

In such film units the positive and negative components are laminated and/ or otherwise retained in superposition by physical means, such as a binding tape, the essential layers comprising the two components being contained either on a single support member or confined between a pair of support members. Where a support member is associated with the positive component where the color image is to be formed, it will be appreciated that at least this support member should be transparent to permit viewing therethrough of the color transfer image. In addition to the aforementioned essential layers, such film units further include means for providing a reflecting layer, most preferably a white reflecting layer, between the dyeable stratum of the positive component and the negative component in order to mask effectively the silver image or images for-med as a function of development and any associated dye image-providing material remaining after development and transfer image formation and to provide a background for viewing the color image so formed in the dyeable stratum, without separation, by reflected light, as is disclosed in the various patents mentioned above. This reflecting layer which may, for example, comprise a white pigment such as titanium dioxide, may be present as a preformed layer included in the essential layers of the film unit or the reflecting agent may be provided after photoexposure, e.g., by including the reflecting agent in the processing composition. The film unit may also contain other layers performing specific desired functions, e.g., spacer layers, barrier layers, neutralizing layers, etc. In a particularly preferred form, these film units are employed in conjunction with a rupturable container of known description containing the requisite processing composition and adapted, upon application of compressive pressure, of applying its contents to develop the exposed film unit, e.g., by applying the processing composition in a substantially uniform layer between the dyeable stratum and the negative component.

Opacifying means may be provided on either side of the negative component so that the film unit may be processed in the light to provide the desired color transfer image. In a particularly useful embodiment such opacifying means may comprise an opaque dimensionally stable layer or support member positioned on the free or outer surface of the negative component, i.e., on the surface of the film unit opposed from the positive component containing the dyeable stratum, to prevent photoexposure by actinic light incident thereon from this side of the film unit and an opacifying agent applied during development between the dyeable stratum and the negative component, e.g., by including the opacifying agent in a developing composition so applied in order to prevent further exposure (fogging) by actinic light incident thereon from the other side of the film unit when the thus exposed film unit is developed in the light. The last mentioned opacifying agent may comprise the aforementioned reflecting agent which masks the negative component and provides the requisite background for viewing the transfer image formed thereover. Where this refiecting agent is insufficient to provide the requisite opacity, it may be employed in combination with an additional opacifying agent in order to prevent further exposure of the light-sensitive silver halide layer or layers by actinic light incident thereon.

In general these film units may be exposed to form a developable image and thereafter developed by applying the appropriate processing composition to develop exposed silver halide and to form, as a function of development, an imagewise distribution of diffusible dye imageproviding material which is then transferred, at least in part, by diffusion to the dyeable stratum to impart thereto the desired color transfer image. As was heretofore mentioned, common to all of these systems is the provision of a reflecting layer between the dyeable stratum and the photosensitive strata to mask effectively the latter and to provide a background for viewing the color image imparted to the dyeable stratum, whereby this image may be viewed, by reflected light, without separation from the other layers or elements of the film unit.

A preferred opacification system to be contained in the processing composition is that described in the copending applications of Edwin H. Land, Ser. No. 43,782, filed June 5, 1970 (now abandoned), and Ser. No. 101,968, filed Dec. 28, 1970, now U.S. Pat. No. 3,647,437 comprising an inorganic reflecting pigment dispersion containing at least one 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 layer and optical reflection density than about 1.0 density with respect to incident visible radiation.

In lieu of having the reflecting pigment contained in the processing composition, e.g., as disclosed in the abovementioned copending applications, the reflecting pigment needed to mask the photosensitive strata and to provide the requisite background for viewing the color transfer image formed in the receiving layer may be contained initially in whole or in part as a preformed layer in the film unit. As an example of such a preformed layer, mention may be made of that disclosed on the copending applications of Edwin H. Land, Ser. Nos. 846,441, filed July 31, 1969, now U.S. Pat. No. 3,615,421, and 3,645, filed Jan. 19, 1970 and now U.S. Pat. No. 3,620,724. The reflecting pigment may also be generated in situ as is disclosed in the copending applications of Edwin H. Land, Ser. Nos. 43,741 and 43,742, both filed June 5, 1970 and now U.S. Pats. Nos. 3,647,434 and 3,647,435, respectively.

Particularly preferred integral negative po sitive film units contemplated by this invention are those described in the aforementioned U.S. Pat. No. 3,415,644 and which comprise a composite structure containing, as essential layers, in sequence, a dimensionally stable alkali solution impermeable opaque layer, a layer containing a cyan dye developer, a red-sensitive silver halide emulsion layer, a layer containing a magenta dye developer, a green-sensitive silver halide emulsion layer, a layer of yellow dye developer, a blue-sensitive silver halide emulsion layer, a dyeable stratum, a spacer layer, a neutralizing layer and a dimensionally stable alkali solution impermeble transparent layer, the composite structure being employed in combination with a rupturable container retaining an aqueous alkaline processing composition including a white reflecting agent (preferably of the type described in the above-mentioned applications which further includes at least one optical filter agent), the container being fixedly positioned and extending along a leading edge of the composite structure so as to be capable of effecting unidirectional discharge of its contents between the dyeable stratum and the blue-sensitive silver halide emulsion layer upon application of compressive pressure. The structural integrity of this film unit may be maintained, at least in part, by the adhesive capacity exhibited between the various layers comprising the laminate at their 0pposed surfaces. However, such adhesive capacity exhibited at the interface intermediate the dyeable stratum and the next adjacent layer of the negative component should be less than that exhibited at the interface between the opposed surfaces of the remaining layers in order to permit distribution of the processing composition between the dyeable stratum and the next adjacent layer of the negative component as contemplated. The structural integrity may also be enhanced or provided in whole or in part by providing a binding member, e.g., a pressuresensitive tape as is described with particularity in the aforementioned patents.

An illustrative negative-positive film unit of the foregoing description is shown in the drawing as comprising, as the essential layers, a layer 13 of cyan dye developer, red-sensitive silver halide emulsion layer 14, interlayer 15, a layer of magneta dye developer 16, green-sensitive silver halide emulsion layer 17, interlayer 18, yellow dye developer layer 19, blue-sensitive silver halide emulsion layer 20, auxiliary layer 21, image receiving layer or dyeable stratum 22, spacer layer 23, and a pH-reducing or neutralizing layer 24. Layers 13-21 comprise the negative component and layers 22-24 comprise the positive component. These essential layers are shown to be confined between a dimensionally stable layer or support member 12 which is preferably opaque so as to permit development in the light and dimensionally stable layer or support member 25 which is effectively transparent to permit viewing of a color transfer image formed as a function of development in receiving layer or dyeable stratum 22.

Layers

12 and 25 are preferably dimensionally stable liquid-impermeable layers which when taken together may possess a processing composition solvent vapor permeably sufiicient to effect, subsequent to substantial transfer image formation and prior to any substantial environmental image degradation to which the resulting image may be prone, osmotic transpiration of processing composition solvent in a quantity effective to decrease the solvent from a first concentration at which the colorproviding material is diffusible to a second concentration at which it is not. Although these layers may possess a vapor transmission rate of l or less gms./24 hrs/ in. /mil., they preferably possess a vapor transmission rate for the processing composition solvent averaging not less than about 100 gms./24 hrs/100 in. /mil., most preferably in terms of the preferred solvent, water, a vapor transmission rate averaging in excess of about 300 gms. of water/24 hrs./100 in. /mil., and may advantageously comprise a microporous polymeric film possessing a pore distribution which does not unduly interfere with the dimensional stability of the layers or, where required, the optical characteristics of such layers. As examples of useful materials of this nature, mention may be made of those having the aforementioned characteristics and which are derived from ethylene glycol terephthalic acid; vinyl chloride polymers; polyvinyl acetate; cellulose derivatives, etc. As heretofore noted layer 12 is of sufiicient opacity to prevent fogging from occurring by light passing therethrough, and layer 26 is transparent to permit photoexposure and for viewing of a transfer image formed on receiving layer 23.

The silver halide layers preferably comprise photosensitive silver halide, e.g., silver chloride, bromide or iodide or mixed silver halides such as silver iodobromide or chloriododbromide dispersed in a suitable colloidal binder such as gelatin and such layers may typically be on the order of 0.6 to 6 microns in thickness. It will be appreciated that the silver halide layers may and in fact generally do contain other adjuncts, e.g., chemical sensitizers such as are disclosed in U.S. Pats. Nos. 1,574,944; 1,623,499; 2,410,689; 2,597,856; 2,597,915; 2,487,850; 2,518,698; 2,521,926; etc.; as well as other additives performing specific desired functions, e.g., coating aids, handeners, viscosity-increasing agents, stabilizers, preservatives, ultraviolet absorbers and/or speed-increasing compounds. While the preferred binder for the silver halide is gelatin, others such as albumin, casein, zein, resins such as cellulose derivatives, polyacrylamides, vinyl polymers, etc, may replace the gelatin in whole or in part. In a typical film unit of the type shown in the drawing, layer 14 may comprise a red-sensitive gelatino silver iodobromide emulsion containing from about 120 to about 180 mgs./ft. of silver; layer 17 may comprise a greensensitive gelatino silver iodobromide emulsion containing from about 100 to about 130 mgs./ft. of silver; and lay-er 20 may comprise a blue-sensitive silver iodobromide emulsion containing from about 100 to about 125 rings/ft. of silver. These illustrative emulsion layers may and typically do contain other materials, as heretofore noted.

The respective dye developers which may be any of those heretofore known in the art, are preferably dispersed in an aqueous alkaline permeable polymeric binder, e.g., gelatin, as a layer from about 1 to 7 microns in thickness. Layer 13 may, for example, include from about 85 to about 130 mgs/ft. of a phthalocyanine cyan dye developer of the type described in U.S. Pat. No. 3,- 482,972; layer 16 may include from about 70 to about 120 mgsJft. of a 1:1 chrome-complexed azo magenta dye developer of the type deecribed in U.S. Pats. Nos. 3,563,739 and 3,551,406; and layer 19 may include from about 65 to about 85 mgs./ft. of a 1:1 chrome-complexed azomethine yellow dye developer of the type described in U.S. Pat. No. 3,597,200.

Interlayers 15 and 18 are of the type to which the present invention is directed. These layers may, for example, contain on the order of from about 50 to about 200 mgs./ft. of solids and the ratio of latex to permeator as well as the total coverage in the respective layers may be the same or different. Preferably, the pH has been adjusted, as heretofore noted, to on the order of 6.0 to 8.5; and the pH of the respective interlayers may also be the same or different. Interlayer 21 preferably comprises an alkaline permeable material such as gelatin. Any of the interlayers may also contain additional reagents performing specific functions. By way of example, interlayers 15 and/ or 18 may include a cross-linking agent such as succindialdehyde, as disclosed in the aforementioned application Ser. No. 119,331. Layer 18 may include an auxiliary developing agent such as 4-methylphenyl hydroquinone.

The image-receiving layer may the on the order of 0.25 to 0.4 mil. in thickness. Typical materials heretofore employed for this layer include dyeable polymers such as nylon, e.g., N-methoxymethyl poly-hexamethylene adipamide; partially hydrolyzed polyvinyl acetate; polyvinyl alcohol with or without plasticizers; cellulose acetate with filler as, for example. one-half cellulose acetate and onehalf oleic acid; gelatin; polyvinyl alcohol or gelatin containing a dye mordant such as poly-4-vinylpyridine, etc. Such receiving layers may, if desired, contain suitable mordants, e.g., any of the conventional mordant materials for acid dyes such as those disclosed, for example, in the aforementioned U.S. Pat; No. 3,227,550; as well as other additives such as ultraviolet absorbers, pH-reducing substances, etc. It may also contain specific reagents performing desired functions, e.g., a development restrainer, as disclosed, for example, in U.S. Pat. No. 3,265,498.

The spacer or timing layer may be on the order of 0.1 to 0.7 mil. thick. Materials heretofore used for this purpose include polymers which exhibit inverse temperature-dependent permeability to alkali, e.g., as disclosed in U.S. Pat. No. 3,445,686. Materials previously employed for this layer include polyvinyl alcohol, cyanoethylated polyvinyl alcohol, hydroxypropyl polyvinyl alcohol, polyvinyl methyl ether, polyethylene oxide, polyvinyl oxazolidinone, hydroxypropyl methyl cellulose, partial acetals of polyvinyl alcohol such as partial polyvinyl butyral and partial polyvinyl propional, polyvinyl amides such as polyacrylamide, etc.

The neutralizing layer may be on the order of 0.3 to 1.5 mil. in thickness. Materials used heretofore in the preparation of this layer include the polymeric acids disclosed in U.S. Pat. No. 3,362,819, e.g., dibasic acid halfester derivatives of cellulose, which derivatives contain free carboxyl groups, e.g., cellulose acetate hydrogen phthalate, cellulose acetate hydrogen glutarate, cellulose acetate hydrogen succinate, ethyl cellulose hydrogen succinate, ethyl cellulose acetate hydrogen succinate, cellulose acetate hydrogen succinate hydrogen phthalate; ether and ester derivatives or cellulose modified with sulfoanhydrides, e.g., with ortho-sulfobenzoic anhydride; polystyrene sulfonic acid; carboxymethyl cellulose; polyvinyl hydrogen phthalate; polyvinyl acetate hydrogen phthalate; polyacrylic acid; acetals of polyvinyl alcohol with carboxy or sulfo substituted aldehydes, e.g., o-, m-, or p-benzaldehyde sulfonic acid or canboxylic acid; partial esters of ethylene/maleic anhydride copolymers; partial esters of methyl-vinyl ether maleic anhydride copolymers; etc.

By way of further illustrating the practice of this invention, an integral negative-positive film unit of the type described and claimed in U.S. Pat. No. 3,415,644 may be prepared, for example, by coating, in succession, on a gelatin subbed, 4 mil. opaque polyethylene terephthalate film base, the following layers:

(1) A layer of cyan dye developer dispersed in gelatin and coated at a coverage of about 100 tugs/ft. of dye and about mgs./ft. of gelatin;

(2) A red-sensitive gelatino silver iodobromide emulsion coated at a coverage of about 140 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 methaerylic acid and polyacrylamide, the ratio of latex copolymer to polyacrylamide permeator being about 28:1, coated at a pH of about 8.2 to provide an interlayer containing about 140 mgs./ft. of solids.

(4) A layer of magenta dye developer dispersed in gelatin and coated at a coverage of about 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 latex and permeator referred to above in layer 3, the ratio of latex to permeator being about 9:1, coated at a pH of about 6.4 to provide an interlayer containing about 107 mgs./ft. of solids.

(7) A layer of yellow dye developer dispersed in gelatin and coated at a coverage of about 70 mgs./ft. 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 mgs./ft. of silver, about 60- mgs./ft. of gelatin and about 30 mgs./ft. of auxiliary developer; and

a yellow dye developer.

Then a transparent 4 mil. polyethylene terephthalate film base may be coated, in succession, with the following illustrative layers:

(1) A polymeric acid neutralizing layer containing a 7:3 mixture, by weight, of polyethylene/maleic anhydride copolymer and 88-90% hydrolyzed polyvinyl acetate at a coverage of about 1000 mgs/ftl";

(2) A graft copolymer of acrylamide and diacetone acrylamide on a polyvinyl alcohol backbone in a molar ratio of 1:3.2:1 at a coverage of about 800 mgs./ft. to provide a polymeric spacer or timing layer; and

(3) A 2:1 mixture, by weight, of polyvinyl alcohol and poly 4 vinylpyridine, at a coverage of about 900 mgs./

ft. and including about 20 mgs./ft. of a development restrainer, 1 phenyl 5 mercaptotetrazole, to provide a polymeric image-receiving layer containing development restrainer.

The two components may then be laminated together to provide the desired integral film unit.

A rupturable container comprising an outer layer of lead foil and an inner liner or layer of polyvinyl chloride retaining an aqueous alkaline processing solution may then be fixedly mounted on the leading edge of each of the laminates, by pressure-sensitive tapes, interconnecting the respective container and laminates so that, upon application of compressive pressure to the container to rupture the containers marginal seal, its contents may be distributed between the dyeable stratum (layer 3 of the positive component) and the gelatin layer (layer 9) of the negative component.

An illustrative processing composition to be employed in the rupturable container may comprise the following properties of ingredients:

Water cc. Potassium hydroxide 11.2 mm. Hydroxyethyl cellulose (l h viscosity) [commercially available from Hercules Powder 00., Wilmington, Delaware,

under the tradcname N atrasol 250] 3.4 gms. N-phenethyl-a-picolinium bromide 2.7 gms. Benzotriazole 1.15

Titanium dioxide--.

CH;NC 1125-11 L0H, II I O OH This film unit may then be exposed in known manner to form a deyelopable image and the thus exposed element, may then be developed by applying compressive pressure to the rupturable container in order to distribute the aqueous alkaline processing composition, thereby forming a multicolor transfer image which is viewable through the transparent polyethylene terephthalate film base as a positive reflection print. As was heretofore discussed, due to the fact that the negative component is suitably protected from fogging, this development may be effected in the presence of actinic light.

In the foregoing illustrative film unit, the negative interlayers wherein the latex possesses the stated particle size were found to be optimum in function in that they function best as a dye barrier against back diffusion and the resulting interimage problems while still permitting the necessary forward diifusion to achieve the desired dye transfer image.

In addition to the sensitometric considerations for employing the latex particle sizes of this invention, i.e., from about 0095a to about 0.115 it has further been found if coarser particle sizes are employed, the latex is not as compatible with the permeator so that there is a tendency for separation or coascervation to provide a coating having inconsistent or irregular degrees of permeability.

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

What is claimed is:

1. In a composition for preparing an interlayer in a photosensitive element for use in color photography, said interlayer comprising a dye-impermeable coalesced essence of an aqueous film-forming polymer dispersion and an aqueous alkaline solution permeable material associated therewith and adapted to render said interlayer permeable to solubilized dye image-forming material subsequent to being contacted with said aqueous alkaline solution, said composition including said coalesced essence dispersion and an aqueous solution of said permeable material;

the improvement wherein the particle size of said coalesced essence is from about 0.095 to about 0.115u.

2. A composition as defined in claim 1 including a cross-linking agent.

3. A composition as defined in claim 2 wherein said agent is succindialdehyde.

4. A composition as defined in claim 1 including a neutralizing agent for raising the pH of said composition.

5. A composition as defined in claim 4 wherein said neutralizing agent is an inorganic base and the pH of said composition is from about 6.0 to about 8.5.

6. A composition as defined in claim 5 wherein said base is ammonium hydroxide, cesium hydroxide or rubidium hydroxide.

7. In a photosensitive element including at least two sets of silver'halide layers each of which has a dye image-providing material associated therewith, the improvement which comprises disposing between said sets an interlayer comprising the composition of claim 1.

8. A photosensitive element comprising a red-sensitive silver halide layer having a cyan dye image-providing material associated therewith; a first interlayer; a greensensitive silver halide layer having a magneta dye imageproviding material associated therewith; a second interlayer; and a blue-sensitive silver halide layer having a yellow dye image-providing material associated therewith, at least one of said interlayers comprising a dye-impermeable coalesced essence of an aqueous filrn-forming polymer dispersion and an aqueous alkaline solution permeable material associated therewith and adapted to render said interlayer permeable to a solution of said dye image-providing material subsequent to being contacted with an 14 aqueous processing composition, said coalesced essence having a particle size from about 0.095 to about 0.115

9. A photosensitive element comprising a layer of a cyan dye developer; a red-sensitive gelatino silver halide emulsion layer; a first interlayer; a layer of a magenta dye developer; a green-sensitive silver halide emulsion layer; a second interlayer; a layer of a yellow dye developer; and a blue-sensitive gelatino silver halide emulsion layer, each of said interlayers comprising a dye-impermeable coalesced essence of an aqueous film-forming polymer dispersion and an aqueous alkaline solution permeable material associated therewith and adapted to render said interlayer permeable to a solution of said dye image-providing material subsequent to being contacted with an aqueous processing composition, said coalesced essence having a particle size from about 0.95 1. to about 0.ll5,u.

10. A film unit as defined in claim 9 wherein the pH of said interlayers is from about 6.0 to about 8.5.

11. A film unit as defined in claim 9 including a dyeable stratum.

12. A film unit as defined in claim 11 including means for providing a reflecting agent between said dyeable stratum and photosensitive strata and associated dye developer, whereby a color transfer image imparted to said dyeable stratum by exposing said film unit and then developing the thus exposed film unit may be viewed, without separation, as a reflection print.

13. A film unit as defined in claim 12 wherein said dyeable stratum is on the side of said blue-sensitive emulsion layer opposed from said yellow dye developer layer and a transparent support is on the side of said dyeable stratum opposed from said blue-sensitive emulsion layer.

14. A photosensitive element including a composite structrue containing, as essential layers, in sequence, a dimensionally stable alkaline solution imperable opaque layer, a layer of a cyan dy image-providing material, a red-sensitive silver halide emulsion layer, a first spacer layer, a layer of a magenta dye image-providing material, a green-sensitive silver halide emulsion layer, a second spacer layer, a layer of a yellow dye image-providing material, a blue-sensitive silver halide emulsion layer, a third spacer layer, a dyeable stratum, a polymeric acid layer containing sufiicient acidifying groups to effect reduction of a processing solution having a first pH at which said image-providing materials are soluble and diifusible to a second pH at which said materials are substantially insoluble and non-ditfusible and a dimensionally stable alkaline solution impermeable transparent layer, each of said first and second spacer layers comprising a dye-impermeable coalesced essence of an aqueous film-forming polymer dispersion and an aqueous alkaline solution permeable material associated therewith and adapted to render said interlayer permeable to a solution of said dye image-providing material subsequent to being contacted with an aqueous alkaline processing solution having said first pH, said coalesced essence having a particle size from about 0.95 11. to about 0.ll5,u; means securing at least the side edges of said opposed layers in fixed relationship; and a rupturable container retaining said aqueous alkaline processing solution having said first pH and containing dispersed therein a white inorganic pigment in a quantity sutficient to mask effectively said silver halide layers and any dye image-providing material associated therewith after development and to provide a background for viewing a diffusion transfer image formed by development of said film unit, by reflected light, through said transparent layer, said rupturable container being fixedly positioned and extending transverse a leading edge of said photosensitive element so as to be capable of eifccting unidirectional discharge of the containers contents between said dyeable stratum and said third spacer layer upon application of compressive force to said container.

15. A film unit as defined in claim 14 wherein each of said dye image-providing materials is a dye developer.

16. A film unit as defined in claim 15 wherein said cyan dye developer is a phthalocyanine dye developer; said magenta dye developer is a 1:1 chrome-complexed azo dye developer and said yellow dye developer is a 1:1 chrome-complexed azomethine dye developer.

17. A film unit as defined in claim 16 wherein the pH of said first and second spacer layers is from about 6.0 to about 8.5.

18. A film unit as defined in claim 15 wherein at least one of said spacer layers includes a tagging cation.

19. A film unit as defined in claim 16 wherein at least one of said spacer layers includes a cross-linking agent.

20. A photographic process for preparing color diffusion transfer images comprising the steps of exposing a photosensitive element as defined in claim 7 to form a developable image; contacting said exposed element with an aqueous alkaline processing composition to develop said image and to form, as a function of development, an imagewise distribution of said dye image-providing material which is soluble and diffusible in said processing composition; and transferring said imagewise distribution at least in part, by diffusion, to a superposed dyeable stratum to impart thereto a color transfer image.

21. A photographic process for forming a color transfer image comprising exposing a film unit of claim 14 to form a developable image; rupturing said container and thereby applying its contents in a layer between said dyeable stratum and said third spacer layer to develop said image and to form, as a function of development, an imagewise distribution of said dye image-providing material which is soluble and diffusible in said aqueous alkaline processing solution; and transferring said imagewise distribution at least in part, by diffusion, to said dyeable stratum to impart thereto a color transfer image which is viewable through said transparent layer as a positive color transfer reflection print.

References Cited UNITED STATES PATENTS 3,625,685 10/1971 Autges et al. 96-3 NORMAN G. TORCHIN, Primary Examiner A. T. SURO PICC'), Assistant Examiner US. Cl. X.R. 96-29 D, 76 C, 77