GB2055110A - Radiation polymerisation of acid reacting layers and photographic products containing such layers - Google Patents

Abstract

Acid-reacting polymeric acid layers in sheet-like elements layers which are utilized in the manufacture of elements employed in photographic diffusion transfer products and processes for control of environmental pH, are formed by the in situ radiation-induced polymerisation of a composition comprising an aliphatic ethylenically- unsaturated carboxylic acid or anhydride and a comonomeric acrylate or methacrylate ester.

Description

SPECIFICATION Radiation polymerisation of acid reacting layers and photographic products containing such layers This invention relates to coated elements comprising a sheet-like element having bonded thereto a polymeric acid reacting layer formed by radiation-induced polymerisation. More particularly, it relates to elements and products utilising a polymerised layer of acid reacting material for control of environmental pH in photographic diffusion transfer products and processes and to methods for making-such elements and products.

Materials for use as polymeric acid reacting materials in such products must meet particular requirements.

For instance a polymeric acid material suited, for example, to application as an acid-reacting reagent in an image-receiving element of a diffusion transfer film unit, in addition to providing required functionality as a pH-reducing material, will be required to be transparent so as to permit viewing of the desired transfer image. Such polymeric layer should be flexible, i.e. exhibit a non-brittle character and should be adherent to the support material. In addition, the polymeric layershould be non-discolouring, compatible with other materials customarily utilised in diffusion transfer film units and be non-contaminating i.e. substantially free of fugitive or migrating monomeric or other species having a deleterious effect upon the diffusion transfer process.A polymeric acid layer suited to application in a diffusion transfer photo-graphic element or product will also be one which can be formed without unreasonable energy requirements.

We have now surprisingly found that despite these requirements it is possible, and indeed advantageous, to make such layers from particular polymerisable mixtures by radiation polymerisation. Radiation polymerisation is, of course, well known as a generality and is known often to be capable of permitting reduced power consumption, improved production rates and economy of operation relative to traditional methods involving solvent removal and recovery. Unfortunately it is often not possible to make by radiation polymerisation polymers intended for particular use requirements.

In the invention coated elements comprising a sheet-like substrate material having bonded thereto an acid reacting layer of polymeric acid material are formed by the radiation polymerisation of a comonomeric mixture of an aliphatic ethylenically-unsaturated carboxylic acid or anhydride and an acrylate or methacrylate ester.The present invention is based in part upon the discovery that such elements, especially useful in photographic products and processes and having a polymeric acid reacting material meeting the requirements to which such layers are subjected in such diffusion transfer products and processes, can be provided by coating a suitable support material with a radiation polymerisable composition comprising an aliphatic ethylenically-unsaturated carboxylic acid or anhydride and a comonomeric acrylate or methacrylate ester, and subjecting the coating to radiation sufficient to polymerise the coating and bond it to the support material.Radiation polymerisation of such a composition by, for example, the use of the ionising radiation of an electron beam accelerator, results in the formation of a transparent, flexible, non-discolouring and non-contaminating laer of acid reacting polymeric material which is compatible with the elements and components of a diffusion transfer product or process and which is strongly bonded to the support material so as to effectively resist delamination under the use conditions of a photographic diffusion transfer film unit.

According to the invention, a product suitable for use in a photographic diffusion transfer process comprises a sheet-like support and an acid reacting polymer layer bonded to the support and formed by radiation polymerisation of a radiation polymerisable composition comprising an aliphatic ethylenically unsaturated carboxylic acid or anhydride and an acrylate or methacrylate ester in a molar ratio of the acid or anhydride to the ester of from 0.5:1 to 15:1. Naturally the amount of radiation should be sufficient to cause polymerisation and bonding of the layer to the support.

A method according to the invention for preparing a photographic product including an acid reacting polymeric layer is characterised by the steps of coating a sheet material with a radiation polymerisable comonomeric mixture of an aliphatic ethylenically unsaturated carboxylic acid or anhydride and an acrylate or methacrylate ester in a molar ratio of acid or anhydride to ester of from 0.5:1 to 15:1 and subjecting the coating to radiation sufficient to polymerise the coating and bond it to the sheet material.

Preferably the amount of the mixture is such that the polymeric layer has an acid reacting functionality in a range of from 108 to 269, most preferably 151 to 215, meq/m2.

The product may include also an alkaline solution permeable timing layer. The product may comprise, in order, the support, the acid reacting layer and the timing layer. The product may also include an alkaline solution permeable and dyeable image receiving layer. This layer may be carried on the support, in which event the product preferably comprises, in order, the support, the timing layer and the image receiving layer.

Generally, any image receiving layer is superposed to the acid reacting layer.

The product may also include at least one silver halide layer having associated therewith an image forming material. Generally, this image forming material is an image dye-providing material. The silver halide layer or layers may be carried on the support.

The invention is of value in various types of photographic product, and in particular in a number of photographic film units for forming diffusion transfer images. Such products often comprise at least one sheet-like support; an image receiving layer; at least one photosensitive silver halide emulsion layer, each silver halide emulsion having associated therewith an image forming material; means for providing a processing composition for developing each silver halide emulsion after photo-exposure and for forming a diffusion transfer image in the image receiving layer; and bonded to at least one sheet-like support an acid reacting polymeric layer as defined in more detail herein.

One such product is for forming an image within a permanent laminate and comprises: a first sheet-like element comprising an opaque support carrying at least one photosensitive silver halide emulsion layer having associated therewith an image forming material; a second sheet-like element comprising a transparent support having bonded thereto an acid reacting polymeric layer as defined in more detail herein and carrying an image receiving layer comprising a dyeable and alkali solution permeable layer in superposed relation to the polymeric acid reacting layer; a rupturable container releasably holding an aqueous alkaline processing composition including a light reflecting pigment material; the first and second sheet-like elements being held in superimposed fixed relationship with the supports outermost during photoexposure and processing and with the at least silver halide emulsion layer being exposable through the transparent support; the rupturable container being positioned so as to release the processing composition for distribution between the sheet-like elements after photoexposure to provide a light reflecting layer of the pigment material, the light reflecting layer providing a background against which the diffusion transfer image formed in the image receiving layer may be viewed through the transparent support without separation of the superposed first and second sheet-like elements.

Another such product comprises: a first sheet-like element comprising a first transparent support having bonded thereto an acid reacting polymeric layer as defined in more detail herein and a second sheet-like element comprising a second support carrying, in sequence, an image receiving layer, a light reflecting layer comprising a light reflecting pigment material and at least one photosensitive silver halide emulsion layer, each silver halide emulsion layer having associated therewith an image forming material; a rupturable container releasably holding an aqueous alkaline opaque procesing composition; the first and second sheet-like elements being held in superposed fixed relationship with said supports outermost during photoexposure and processing and with the at least one silver halide emulsion layer being exposable through the first transparent support; the rupturable container being positioned so as to release the aqueous alkaline opaque processing composition for distribution between the first and second sheet-like elements.

Another product of the invention is a photographic film unit for forming a diffusion transfer image comprising a photosensitive element comprising a support carrying at least one silver halide emulsion layer having associated therewith an image providing material; an image receiving element adapted to be separated from said photosensitive element after transfer image formation and comprising a support having bonded thereto an acid reacting polymeric layer as defined in more detail herein the acid reacting polymeric layer carrying an alkali permeable and dyeable image receiving layer; and, integrated with the photosensitive and image receiving elements, means for retaining a processing composition can be distributed between the superposed elements after photoexposure of the photosensitive element.

The invention is now described in more detail and with reference to the accompanying drawings in which Figure 1 is a diagrammatic cross-sectional view of an article of the invention comprising a sheet element having bonded thereto a radiation-polymerised acid-reacting polymeric layer material and having thereon a timing layer.

Figure 2 is a diagrammatic cross-sectional view of an image-recording element of the invention comprising a support material, a radiation-polymerised acid-reacting layer, a spacer or timing layer and an image-receiving layer.

Figure 3 is a simplified or schematic view of an arrangement of elements of a preferred film unit of the invention embodying a radiation-polymerised acid-reacting polymeric layer and which is shown after exposure and processing.

Figures 4 and 5 are simplified or schematic views of other preferred arrangements of film units of the present invention embodying a radiation-polymerised acid-reacting layer and which are shown after exposure and processing.

The radiation-polymerizable comonomeric mixture of aliphatic ethylenically-unsaturated carboxylic acid or anhydride and acrylate or methacrylate ester described herein can be utilized for the formation of polymeric acid-reacting layers strongly bonded to a support material so as to provide articles useful in different types of photographic diffusion transfer products and processes. Thus, a suitable support material is provided with a coating of such mixture of radiation-polymerizable composition and subjected to radiation sufficient to effect polymerization thereof.In accordance with one embodiment of the invention, an element having such radiation-polymerized layer is provided with a suitable timing layer for the provision of an element suited to employment as a spreader sheet or element for the facilitation of the uniform spreading or distribution of an alkaline processing composition in a photographic diffusion transfer film unit. In another embodiment of the present invention, a suitable support carrying an acid-reacting layer as described herein, by the integration of at least a dyeable stratum, can be utilized as an image-receiving element useful in photographic diffusion transfer products and processes and as shown generally at Figure 2. A support material having bonded thereto a radiation-polymerized acid-reacting layer as herein described can also, by the integration of additional layers of components, be utilized in the provision of photographic diffusion transfer products as shown generally in Figures 3 to 5.

The first essential component of the radiation-polymerizable compositions utilized in the conduct of the present invention is an aliphatic ethylenically-unsaturated carboxylic acid or anhydride. The acidic or anhydride component provides in the radiation-polymerized or cured layer, the acid-reacting functionality important in diffusion transfer products and processes for the control of environmental pH as previously described in the art.

As used herein in reference to the radiation-polymerized or cured layer, the term "acid-reacting" refers to the acidic nature of the layer in its reactions. Aliphatic ethylenically-unsaturated carboxylic acids or their anhydrides which are hydrolyzable under aqueous use conditions to the corresponding acids can be utilized to provide such acid-reacting layers. Thus, the utilization of such acid or anhydride monomer components permits the formation of a polymeric layer which can be utilized to lower the environmental pH of a diffusion transfer process following substantial dye transfer and provide desired image stability in the manner described, for example, in U.S. Patents 3,362,819; 3,362,821; 3,415,644; 3,594,165.Examples of suitable acid-reacting monomers useful herein are the aliphatic ethylenically-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, 3-chloro-2-methyl acrylic acid, 3-butenoic acid, 4-pentenoic acid, 2-hexenoic acid, the corresponding anhydrides and mixtures thereof. Preferred acid-reacting monomeric materials are the acid of the formula:

wherein R is hydrogen and R1 and R2 are each hydrogen or alkyl of from 1 to 3 carbon atoms and the corresponding anhydrides. Especially preferred herein is acrylic acid. While reference is made throughout the present specification to aliphatic ethylenically-unsaturated carboxylic acid as suitable acid-reacting materials, it will be appreciated that such term is utilized herein as likewise including the corresponding anhydride materials.Such anhydrides are hydrolyzed under aqueous conditions, e.g., the aqueous alkaline conditions of a photographic processing composition, to a corresponding acid and can be utilized herein.

The second essential component of the radiation-polymerizable composition is an acrylate or methacrylate ester. The ester component provides important functions in the provision of a polymerized acid-reacting layer having a high level of acid-reacting functionality and a relatively low content of water-extractable and unreacted monomeric or other fugitive or mobile species that may have a deleterious effect upon the diffusion transfer process. The ester component, which imparts hydrophobicity and reduces the volatility and exotherm of the polymerization reaction, is believe to promote completeness of polymerization and provision of an acid-reacting polymer layer having a high level of acid-reacting functionality.Additionally, the resulting polymerized acid-reacting layer exhibits good adhesion to the support material, paticularly in the swollen state which is promoted by contact with an aqueous alkaline processing composition customarily utilized in diffusion transfer processing.

It has been found, from attempts to prepare a polymeric acid-reacting layer of poly (acrylic acid), that the radiation-induced polymerization of acrylic acid results in the formation of a polymeric material having an undesirable level of water-extractable species. Such water-extractable species may adversely affect the diffusion transfer process as a result oftheirfugutive or migrating character and their presence in an acid-reacting polymeric layer is desirably minimized or avoided.

The utilization of a comonomeric species of acrylate or methacrylate ester in the polymerization of the acid-reacting ethylenically-unsaturated carboxylic acid permits the desired formation of a polymeric layer having a reduced level of such water-extractable species. In addition, the resulting polymeric layer exhibits greater flexibility and clarity.

The acrylate or methacrylate esters utilized herein are esters of acrylic or methacrylic acid and include, for example, hydrocarbyl esters of acrylic acid or methacrylic acid. Suitable hydrocarbyl esters include esters of acrylic or methacrylic acid and alkanol, e.g., the methyl, ethyl, isobutyl, n-hexyl, 2-ethylhexyl, decyl or isodecyl esters of acrylic or methacrylic acid; and esters of acrylic or methacrylic acid and a cycloaliphatic alcohol, e.g., cyclohexyl, isobornyl, dicyclopentadienyl acrylate or methacrylate. Other hydrocarbyl acrylates and methacrylates suited herein are the aryl acrylates and methacrylates, e.g., phenyl acrylate; alkaryl acrylates and methacrylates, e.g., tolyl acrylate or methacrylate; and aralkyl acrylates and methacrylates, e.g., benzyl acrylate and methacrylate.Among suitable esters of acrylic or methacrylic acid and a heterocyclic alcohol mention may be made of tetrahydrofurfuryl acrylate and methacrylate. The acrylates and methacrylates herein described can be derived from acrylic or methacrylic acids and an alcohol having one or more substituents exemplified by aryloxy, alkoxy, ether, nitro, ester or the like provided that such substituents are not present in such amount or proportion as to alter substantially the hydrocarbyl nature of the alcohol-derived moiety or otherwise interfere with the desired polymerization reaction. Such acrylates or methacrylates are inclusive, for example, of aryloxyalkyl acrylates and methacrylates such as phenoxyethyl acrylate and methacrylate; and alkoxyalkyl acrylates and methacrylates such as methoxyethyl acrylate and methacrylate.

Preferred acrylate and methacrylate esters are those which impart hydrophobicityto the copolymerizable mixture of ethylenically-unsaturated acid and acrylate or methacrylate ester and which are normally liquid or solid so as to facilitate desired coating of the mixture and minimize volatiles losses. Suitable esters from these standpoints are benzyl acrylate, 2-phenoxyethyl acrylate, isobornyl acrylate, dicyclopentadienyl acrylate, cyclohexyl acrylate and the corresponding methacrylates. These esters can be readily coated onto a suitable substrate and polymerized to desired acid-reacting polymeric layers.

The proportions of each of the aliphatic ethylenically-unsaturated carboxylic acid and acrylate or methacrylate ester components of the radiation-polymerizable composition utilized herein can vary depending upon the particular nature of such components utilized, the desired thickness of the polymeric coating and the particular and desired properties thereof. In general, the ethylenically-unsaturated carboxylic acid will be employed in the radiation-polymerizable composition in an amount to provide the radiation-polymerized layer with the acidic functionality requisite for desired environmental pH control.

Similarly, the acrylate or methacrylate ester will be employed in an amount sufficient to provide substantially complete polymerization of the ethylenically-unsaturated carboxylic acid and the manufacture of a polymeric acid-reacting layer relatively free of unreacted acidic monomer and other fugutive or mobile species that might exhibit a harmful or deleterious effect on a photographic diffusion transfer process. In general, the ethylenically-unsaturated carboxylic acid and acrylate or methacrylate ester components will be utilized in the radiation-polymerizable composition in molar proportions, respectively, of from about 0.5:1 to about 15:1. Preferably, such components will be utilized in proportions of from about 1.5:1 to about 10:1.

Such proportions permit the manufacture of an acid-reacting polymeric layer having desired acidic functionality without the need to resert to high substrate coverage rates that may adversely affect the flexibility or other physical characteristics of the polymeric layer. Additionally, the utilization of such proportions permits desired control of extractable acid levels in the polymeric layer. In a preferred practice of the invention, a radiation-polymerizable mixture of acrylic acid and 2-phenoxyethyl acrylate is utilized for the provision on a suitable substrate material of an acid-reacting polymeric layer having preferred properties from the stand-points of low water-extractable and unreacted monomeric species.

The acid-reacting polymeric layer bonded to the support material on which it is polymerized can be formed by applying the radiation-polymerizable composition to the support material and effecting polymerization thereof by subjecting the support and coating to a suitable form of polymerizing irradiation. The nature of the support employed will depend upon the particular application contemplated for the resulting support carrying the polymeric acid-reacting layer. Typically, the support material will comprise a support onto which the radiation-polymerizable composition can be suitably applied for polymerization and will include glass, paper, metallic and polymeric support materials derived from naturally occurring products or of a synthetic type.Thus, paper; aluminium, methyl and ethyl esters of polymethacrylic acid; vinyl chloride polymers; polyvinyl acetal; polyamides such as nylon; polyesters such as ethylene glycol terephthalate or such cellulosic derivatives as cellulose acetate, triacetate, nitrate, propionate, butyrate, acetate-propionate or acetate-butyrate can be employed. It will be apparent that, depending upon the desired application of the substrate material carrying the polymeric acid-reacting layer, the nature of the substrate material as a transparent, translucent or opaque suppot will be a matter of choice. It will be appreciated that, in the case of photographic applications where a photographic image is desirably viewed through the substrate carrying the acid-reacting polymeric layer, a transparent support material will be utilized.A preferred support material is a transparent web or sheet material onto which the radiation-polymerizable composition can be suitable applied and polymerized with the provision of a transparent element suited to such application.

The support material can, where desired, be subjected to a pretreatment step prior to the application and polymerization of the radiation-polymerizable composition. Such pretreatment step can be employed to facilitate adhesion between the polymeric layer and the support material and can comprise, for example, a corona discharge treatment as is known in the art. Polymeric layers, of vinylidene chloride, gelatin, polyvinyl alcohol or the like can be utilized as sub-coats onto which the acid-reacting polymeric layer is formed. Such pretreatment or utilization of sub-coats need not, however, be employed and the radiation-polymerizable composition can be applied to the substrate material without such pretreatment or sub-coats with formation of the desired polymeric layer by in situ polymerization as herein described.

The radiation-polymerizable composition can be applied to the support material on which it is polymerized and bonded in any of a number of ways. For example, the composition can be applied to the substrate material by roll coating, gravure coating, extrusion coating, doctor-blade coating, air-knife coating, curtain coating, or the like. A preferred means for effecting the application of the radiation-polymerizable composition onto the sheet material involves advancing a continuous web or sheet of support material through a coating zone in which the radiation-polymerizable composition is applied in a uniform and continuous manner utilizing any of the aforesaid coating techniques. The viscosity of the radiation polymerizable composition applied to the substrate material will vary depending upon the particular monomeric components thereof and their relative proportions. In general, the composition will be applied to the support material in the form of a relatively thin coating and the relative conformation of the applied coating will be retained as the substrate carrying the coating is advanced to the polymerizing or curing operation.

The amount of radiation-polymerizable composition applied to the substrate material will vary with the particular composition employed, the desired level of acid-reacting functionality, the coating technique utilized, the conditions utilized in the polymerization or curing thereof, particularly the radiation dose, and the particular use or application contemplated for the polymer-carrying substrate material. Normally, acid-reacting polymeric layers exhibiting good adhesion properties and low levels of water-extractable components can be conventionally obtained by applying to a suitable substrate material for subsequent radiation polymerization a thin coating of the radiation-polymerizable composition.In accordance with a preferred embodiment of the invention, a coating of radiation-polymerizable composition will be applied to a suitable support material in an amount sufficient to provide the desired acid-reacting functionality, usually from about 10 to about 25 milli-equivalents of neutralization capacity per square foot (about 108 to about 269 meq./m2), and preferably, from about 14 to about 20 meq./ft2 (about 151 to about 215 meq./m2).

The radiation-polymerizable composition can be polymerized or cured to a solid acid-reacting layer by resort to any of a variety of known techniques for effecting radiation polymerization or curing of radiation-polymerizable or curable compositions. Apparatus and methods for effecting such polymerization or curing are well known and include, for example, the utilization of actinic radiation such as ultra-violet radiation of suitable intensity and high-energy ionizing radiation such as x-rays, gamma rays, beta rays and accelerated electrons. Typically, the radiation utilized will be of a sufficient intensity to penetrate substantially the coated layer of radiation-polymerizable composition and the dosage employed will be sufficient to effect the polymerizaton of the radiation-polymerizable composition to a solid or non-tacky polymeric layer.The amount of radiation employed will, however, vary with the thickness of coating and the speed with which the coated substrate is advanced through the irradiation zone. Typically, a dosage in the range of from about 1 to about 20 megarads, and more usually in the range of from about 2 to about 6 megarads, will be employed. The amount of radiation utilized for polymerization of the radiationpolymerizable composition can be supplied as a single dose of irradiation. Alternatively, a coated substrate can be subjected to multiple passes through the irradiation zone to effect polymerization.

The polymerization of the radiation-polymerizable composition by the utilization of actinic light can be effected by subjecting the composition on a suitable substrate to a source of actinic light such as ultraviolet light. In general, sources of such light in the range of from about 1800 to about 4000 Angstroms can be employed. Suitable sources of such actinic light include mercury arc quartz lamps, carbon arcs, plasma arcs and ultraviolet-emitting lamps of the mercury-vapor type. When the polymerization of the radiationpolymerizable composition is effected by the utiliztion of ultraviolet radiation, a photoinitiatorwill be included in the composition.Examples of photoinitiators which have been described in the art for such purposes include butyl benzoin ether, isobutyl benzoin ether, ethylbenzoin ether, benzophenone, benzoin, acetophenone, dimethyl quinoxiline, 4,4'-bis (dimethylamino)benzophenone and the like. Such photoinitiators, which may be used singly or in admixture, need not be employed when the polymerization is effected by high-energy electrons.

A preferred practice of the invention comprises the utilization of ionizing irradiation for the polymerization of the radiation-polymerizable composition. As used herein, the term "ionizing irradiation" refers to radiation of an energy sufficient to produce ions or to break chemical bonds and is inclusive of high-energy radiation and/or the secondary energies resulting from conversion of electrons or other particle energy to X-rays or gamma radiation. While such high-energy ionizing radiation as X-rays, gamma rays or beta rays can be utilized to effect polymerization, it will be preferred from the standpoints of convenience and economic efficiencies to utilize a source of accelerated high-energy electrons.Various types of high-power electron linear accelerators are commercially available and produce ionizing electromagnetic irradiation as the result of bombardment of a metallic target such as tungsten with electrons of high energy conferred by potential accelerators of over 0.1 million electron volts (mev.). Typically, an electron beam will be provided as a single-point electron beam or in the form of a curtain from a wire filament electron source. Examples of commercially available sources of ionizing electromagnetic irradiation include such equipment as the ARCO-type travelling wave accelerator, Model Mark I, operating at 3 to 10 million electron volts, such as supplied by High Voltage Engineering Corp., Burlington, Massachusetts; a filament-source Electrocurtain system, while as available from Energy Sciences, Inc., Woburn, Massachusetts; and other accelerators as described in U.S.Patent 2,763,609 and in British Patent 762,953.

While the utilization of inionizing electromagnetic irradiation in the form of an ion beam constitutes a preferred practice of the invention, it is intended that ionizing radiation inclusive of ionizing particle radiation can also be employed. The term "ionizing particle radiation" is used herein to designate the emission of electrons or highly accelerated nuclear particles such as protons, neutrons, alpha particles, deuterons, beta particles, or their analogs, directed in such a way that the particle is projected into the mass to be irradiated.

Charged particles can be accelerated by the aid of voltage gradients by such devices as accelerators with residence chambers, Van der Graaff generators, betatrons, synchrotons, cyclotrons, or the like. Neutron radiation can be produced by bombarding a selected light metal such as berylium with positive particles of high energy. Particle radiation can also be obtained by the use of an atomic pile, radioactive isotopes or other natural or synthetic radioactive materials.

The polymerization of the radiation-polymerizable composition can be effected in the presence of an inert atmosphere so as to minimize the inhibitory effects of oxygen. Accordingly, the copolymerizable mixture can be applied in a coating zone which is substantially oxygen-free by utilization of an inert gas flush or purge, e.g., a nitrogen purge. Similarly, the polymerization reaction can be effected by irradiating the copolymerizable mixture in an inert atmosphere and the polymerized coating can be advanced into an inert atmosphere until the temperature of the polymer-containing substrate approaches ambient temperature.

Additives in the nature of oxygen scavengers, e.g., triphenyl phosphine, can also be utilized and can conveniently be employed in the comonomeric polymerizable composition as a means of minimizing the polymerization-retarding or inhibiting effects of oxygen.

Additional components, e.g., photoinitators as described hereinbefore, UV stabilizers, opacification agents, plasticizers, surface-active agents or the like, can also be employed for their known purposes in the radiation-polymerizable compositions utilized herein. Preformed polymers can be employed to facilitate coatability, to provide hydrophobicity or the like. Suitable polymeric materials for addition to the copolymerizable composition includes cellulosic derivatives such as cellulose acetate butyrate or ethyl cellulose.

The radiation-polymerizable compositions described herein can be utilized to provide aticles or products having a polymeric acid-reating layer useful in different types of diffusion transfer photographic products where control of environmental pH is advantageously employed. In one embodiment of the present invention, there is provided an article, generally shown in Figure 1, useful as a spreading sheet to facilitate the uniform spreading or distribution of alkaline processing composition in a diffusion transfer film unit and to provide predetermined pH reduction in such a film unit.

Referring to Figure 1,there is shown a coated article of the invention 10 comprising support material 12 carrying a layer of acid-reacting polymer formed by the radiation-induced polymerization of a radiationpolymerizable composition as herein defined. Such an article can be employed, for example, as a spreader sheet in a diffusion transfer process. Support material 12 can comprise any of the support materials described hereinbefore. Depending upon the particular application intended for the polymer layercontaining article, support 12 can be opaque, translucent or transparent. A preferred applicaton of article 10 is in the manufacture of diffusion transferfilm units of the type shown in Figures 3 and 4 described in greater detail hereinafter.It will be preferred for such applications that support 12 be a transparent sheet-like support material in the nature of polyethylene glycol terephthalate or the like. Article 10 is shown in Figure 1 as including a timing layer 16. Timing layer 16 provides a means by which the initiation and rate of capture of alkali by acid-reacting layer 14 can be controlled in a diffusion transfer process. Materials suited for the provison of timing layer 16 include, for example, gelatin, polyvinyl alcohol or other polymer through which alkali may diffuse to the polymeric acid-reacting layer 14. A preferred timing layer comprises a blend of a tetrapolymer of butyl acrylate/diacetone acrylamide/styrene/methacrylic acid and polyvinyl alcohol. Other timing layer materials are set forth, for example, in U. S. Patents 3,362,819; 3,419,389; 3,421,893; 3,455,686; 3,577,237; and 3,575,701.

In Figure 2 is shown an image-receiving element 20 of the invention comprising a suitable support 22, a radiation-polymerized acid-reacting layer 24 as herein described, a timing layer 26 and an image-receiving layer or stratum 28 of suitable dyeable material. Image-receiving element 20 can be conveniently manufactured by passing a suitable sheet-like support material 22, preferably of transparent material, into a coating zone for coating the polymerizable composition and advancing the coated support material into an irradiated zone to effect polymerization of the coated composition and formation of radiation-polymerized acid-reacting layer 24. An image-receiving layer 28, of polyvinyl alcohol, for example, can then be applied to polymeric acid layer 24 by resort to known methods for the formation thereof.Optionally, and preferably, a timing or spacer layer 26 will be applied to polymeric acid layer 24 and image-receiving layer 28 will be applied over such timing or spacer layer 26 as shown in Figure 2. The resulting image-receiving element can be utilized in photographic diffusion transfer products and processes as shown generally in Figure 3 and described in greater detail hereinafter.

The acid-reacting radiation-polymerized layers prepared in accordance with the present invention find applicability to a number of photographic diffusion transfer products and processes. A preferred embodiment of the present invention is based upon the utilization of such acid-receiving polymeric layers in photographic film units adapted to the provision of photographs comprising the developed silver halide emulsion(s) retained as part of a permanent laminate, with the desired image being viewed through a transparent support against a reflecting background. In such photographs, the image-carrying layer is separated from the developed silver halide emulsion(s). Diffusion transfer photographic products providing an image viewable without separation against a reflecting background in such a laminate have been referred to in the art as "integral negative-positive film units".

Integral negative-positive film units of a first type are described, for example, in U.S. Patent No. 3,415,644 and include appropriate photosensitive layer(s) and image dye-providing materials carried on an opaque support, an image-receiving layer carried on a transparent support and means for distributing a processing composition between the elements of the film unit. Photoexposure is made through the transparent support carrying the acid-reacting radiation-polymerized layer of the invention and the image-receiving layer. A processing composition containing a reflecting pigment is distributed between the image-receiving and photosensitive components. After distribution of the processing and composition and before processing is complete, the film unit can be, and usually is, transported into light. Accordingly, in integral negativepositive film units of this type, the layer provided by distributing the reflecting pigment provides a reflecting background for viewing through the transparent support the image transferred to the image-receiving layer.

Integral negative-positive film units of a second type, as described, for example, in U.S. Patent No.

3,594,165, include a transparent support, carrying the appropriate photosensitive layers and associated image dye-providing materials, a permeable opaque layer, a permeable and preformed light-reflecting layer, and means for distributing a processing composition between the photosensitive layer and a transparent cover or spreader sheet carrying an acid-reacting radiation-polymerized layer as herein described. Integral negative-positive film units of this second type include an opaque processing composition which is distributed after photoexposure to provide a second opaque layer which can prevent additional exposure of the photosensitive element. In film units of this second type, exposure is made through the transparent cover or spreader sheet. The desired transfer image is viewed against the reflecting pigment-containing layer through the transparent support element.

The arrangement and order of the individual layers of the diffusion transfer film units described herein may vary in many ways as is known in the art, provided the film units comprise an acid-reacting radiation polymerized layer bonded to a suitable support or sheet-like element thereof. For convenience however, the more specific descriptions of the invention hereinafter set forth will be by use of dye developer diffusion transfer color processes and of diffusion transfer film units of the type generally contemplated in previously mentioned patents. Thus, details relating to integral negative-positive film units of the first type described hereinbefore can be found in such patents as U. S. Patents 3,415,644 and 3,647,437 while details of the second type are found in U.S. Patents 3,594,165.It will be readily apparent from such descriptions that other image-forming reagents may be used, e.g., color couplers, coupling dyes, or compounds which release a diffusible dye or dye intermediate as a result of coupling or oxidation.

Referring now to the drawings, Figure 3 shows a film unit of the type described in referenced U.S. Patents 3,415,644 and 3,657,437, following exposure and processing. The film unit 30 includes a radiationpolymerized acid-reacting layer 34 of the invention. After photoexposure of photosensitive layer(s) 42 through transparent support 32, radiation-polymerized acid-reacting layer 34, timing layer 36 and image-receiving layer 38, the processing compositon retained in a rupturable container (not shown) is distributed between layers 38 and 42. Processing compositions used in such film units of the present invention are aqueous alkaline photographic processing compositions comprising a reflecting pigment, usually titanium dioxide, and a polymericfilm4orming agent and will preferably contain an optical filter agent described in detail in U.S. Patent 3,647,437.

Distribution of the processing composition over photoexposed portions of photosensitive system 42 provides a light-reflecting layer 40 between image-receiving layer 38 and photosensitive layer(s) 42. This layer, at least during process provides sufficient opacity to protect photosensitive system 42 from further photoexposure through transparent support 32. As reflective layer 40 is installed, by application of the processing composition, development of photoexposed photosensitive layer(2) 42 is initiated to establish in manners well known in the art an imagewise distribution of diffusible image-providing material which can comprise soluble silver complex or one or more dye or dye intermediate image-providing materials.The diffusible image-providing material is transferred through permeable, light-reflecting layer 40 where it is mordanted, precipitated or otherwise retained in known manner in or on image-receiving layer 38 where the transfer image is viewed through transparent support 32 against light-reflecting layer 40.

The light-reflecting layer 40 provided by the embodiment of the invention shown in Figure 3 is formed by solidification of the stratum of processing composition distributed after exposure. The processing composition will include the film-forming polymer which provides the polymeric binder matrix for the light-reflecting pigment of layer 40. Absorption of water from the applied layer of processing composition results in a solidified film comprising the polymeric binder matrix and the pigment material, thus, providing the light-reflecting layer 40 which permits the viewing thereagainst of image 38 through tranparent support 32. In addition, light-reflecting layer 40 serves to laminate together the developed photosensitive system 42 and the image bearing layer 38 to provide the final photographic laminate.

The radiation-polymerized acid-reacting layer 34 of film unit 30 provides important functions in the processing thereof to the desired photographic laminate. The processing compositions typically employed in diffusion transfer processes of the type contemplated herein will generally comprise an aqueous alkaline composition having a pH in excess of about 12, and frequently in the order of 14 or greater. The liquid processing composition permeates the emulsion layer(s) of the photosensitive element to effect development thereof. The elevated environmental pH conditions of the film unit upon spreading or distribution of the alkaline processing composition are conducive to the transfer of image dyes.The radiation-polymerized acid-reacting layer 34 is, thus, employed to lower in predetermined manner the environmental pH of the film unit following substantial dye transfer in order to increase image stability and/or adjust the pH from the first pH at which the image dyes are diffusible to a second and lower pH at which such image dyes are not diffusible. Simultaneously, the reduction of pH permits decolorization of opacification dyes utilized in the film unit to provide in-light development capability.

In each of the articles shown in Figures 2 to 5 is shown a timing layer, which is optionally, but preferably, included for the control of the pH-reducing properties of the polymeric acid-reacting layer. Thus, there is shown in Figure 3, timing layer 36 positioned between radiation-polymerized acid-reating layer 34 and image-receiving 38. The space layer will be comprised of polyvinyl alcohol, gelatin or other polymer through which the alkali may diffuse to the polymeric acid-reacting layer. The presence of such a timing layer between the image-receiving layer 38 and the acid-reacting layer 34 effectively controls the initiation and the rate of capture of alkali by the acid-reacting layer. Suitable materials for the formation of timing layers and the advantages thereof in diffusion transfer systems are described with particularity in U.S. Patents 3,362,819; 3,419,389; 3,421,893; 3,455,686; 3,577,237; and 3,575,701.

In each of image-receiving element 20 of Figure 2 and film units 30, 50 and 60 of Figures 3,4 and 5, respectively, is shown an image-receiving layer comprising a dyeable stratum which mordants or otherwise fixes the desired transfer image. Thus, there is shown in Figure 3, image-receiving layer 38, corresponding generally to image-receiving layer 28 shown in image-receiving element 20 of Figure 2, and comprising any of a variety of dyeable materials heretofore utilized as image-receiving layers in diffusion transfer photographic processes.

In accordance with a preferred embodiment of the invention, a photographic film unit will comprise a temporary laminate including the several layers of the photographic film unit confined between two dimensionally stable supports and having the bond between a predetermined pair of layers being weaker than the bond between other pairs of layers. Thus, with reference to Figure 3, an image-receiving element 32a, comprising transparent support 32, radiation-polymerized acid-reacting layer 34, timing layer 36 and.

image-receiving layer 38 and corresponding generally to image-receiving element 20 of Figure 2, can be arranged in article 30 such that image-receiving layer 38 is temporarily bonded to the silver halide emulsion layer 42 prior to exposure. The rupturable container or pod (not shown) can then be positioned such that, upon its rupture, the processing composition will delaminatethetemporary bond and be distributed between the aforesaid layers 38 and 42. The distributed layer of processing composition upon drying forms light-reflecting layer 40 which serves to bond the layers together to form the desired permanent laminate.

Procedures for forming such prelaminated film units, i.e., film units in which the several elements are temporarily laminated together prior to exposure, are described, for example, in U.S. Patent No. 3,625,281 issued to Albert J. Bachelder and Frederick J. Binda and in U. S. Patent No. 3,652,282 to Edwin H. Land, both issued March 28, 1972. A particularly useful and preferred prelamination utilizes a water-soluble polyethylene glycol is described and claimed in U. S. Patent 3,793,023, issued February 19,1974two E. H.

Land.

If desired, the film unit shown in Figure 3 may utilize a transprent support instead of the opaque support 44 shown therein. In accordance with this alternative embodiment, an opaque layer, e.g., pressure-sensitive, should be superposed over said transparent support to avoid further exposure through the back of the film unit during processing outside of the camera. In the embodiment illustrated in Figure 3, photoexposure is effected through the image-receiving element. While this is a particularly useful and preferred embodiment, it will be understood that the image-receiving element may be initially positioned out of the exposure path and superposed upon the photosensitive element after photoexposure, in which event the processing and final image stages would be the same as in Figure 3.

In Figure 4 is shown, following exposure and processing, a second integral negative-positive type of diffusion transfer film unit of the invention utilizing an arrangement of elements generally described in U.S.

Patent 3,594,165 and British Patent 1,330,524. Such arrangement provides an integral negative-positive reflection print and exposure and viewing are effected from opposite sides. Film unit 50 includes a processing composition initially retained in a rupturable container (not shown) arranged to distribute the processing composition between photosensitive system or layer 60 and a cover or spreader sheet 68a comprising a transparent sheet material 68, radiation-polymerized acid-reacting layer 66 of the invention and optional timing layer 64. Such a spreader sheet, 68a, shown generally in Figure 1 as article 10, facilitates uniform distribution of processing composition after photoexposure of photosensitive system or layer 60 which is effected through transparent sheet material 68.Processing compositions used in such film units are aqueous, alkali photographic processing compositions which include a light-absorbing opacifying agent, e.g., carbon black.

Distribution of the processing composition between photoexposed photosensitive system or layer 64 and spreader sheet 68a installs and opaque layer 62 which protects system or layer 60 from further photoexposure through transparent spreader sheet 68a. Like the film units of Figure 3, as and after opaque layer 62 is installed, the processing composition initiates development of photoexposed photosensitive system or layer 60 to establish an imagewise distribution of diffusible image-providing material in manners well known to the art. For example, the processing composition alone may cause development or developing agents may be in film unit so that they can be carried to system or layer 60 by the processing composition.The diffusible imagewise distribution is transferred to image-receiving layer 54 through permeable light-reflecting layer 56 which comprises a preformed layer including a light-reflecting pigment.

Film units of the type shown in Figure 4 may also comprise a preformed and permeable opaque layer 58 including a light-absorbing pigment, e.g., a dispersion of carbon black in a polymer permeable to the processing composition. Such layer between photosensitive system or layer 60 and light-reflecting layer 56, permits in-light development of film unit 50, providing opacification for the protection of photoexposed photosensitive system of layer 60 against further exposure through transparent support 52 and layers 54 and 56. The transfer image is viewed through transparent support 52 against light-reflecting layer 56.

The radiation-polymerized acid-reating layers of the invention can be utilized in so-called peel-apart diffusion transferfilm units designed to be separated after processing. Such a diffusion transfer film unit of the invention is shown Figure 5 as film unit 70. The film unit shown in Figure 5 comprises a photosensitive element 72a comprising an opaque support 72 carrying a photosensitive layer or system 74. In film units of this type, the photosensitive layer or system 74 is photoexposed and a processing composition 76 is then distributed over the photoexposed layer or system. An image-receiving element 86a, corresponding generally to image-receiving element 20 of Figure 2, is superposed on the photoexposed photosensitive element.As shown in Figure 5, image-receiving element 86a comprises an opaque support material 86, and a light-reflecting layer 84, against which the desired transfer image is viewed and which typically will comprise a polymeric matrix containing a suitable white pigment material, e.g., titanium dioxide. A radiation-polymerized acid-reacting layer 82 of the invention is shown bonded to light-reflecting layer 84 on which is shown optional timing layer 80 and, in turn, image-receiving layer 78, each of which layers is comprised of materials described hereinbefore in connection with the articles and film units shown in Figures 1 to 4.Like the film units shown in Figures 3 and 4, the processing composition permeates photoexposed photosensitive layer or system 74 to provide an imagewise distribution of diffusible dye image-providing material which is transferred at least in part to image-receiving layer 78. Unlike the film units of Figures 3 and 4, however, the transferred dye image is viewed in image-bearing layer 78 against light-reflecting layer 84 after separation of image-receiving element 86a from photosensitive element 72a.

While support material 86 of image-receiving element 86a is shown as being of opaque material, it will be appreciated that a transparent support material can be employed and that the film unit can be processed in the dark or an opaque sheet (not shown), preferably pressure-sensitive, can be applied over such transparent support to permit in-light development. In accordance with a preferred embodiment of the invention, whereby a reflection print is provided upon separation of image-receiving element 86a from photosensitive element 72a, opaque support 86 and light-receiving layer 84, will comprise, for example, a suitable paper support, coated, preferably on both sides, with a polymeric coating, e.g., polyethylene, pigmented with titanium dioxide.Such a support material can be suitably coated with a radiation-polymerizable composition of the invention and polymerized or cured as described hereinbefore. The resulting article can then be provided with optional timing layer 80 and image-receiving layer 78 as shown in Figure 5 with formation of image-receiving element 86a.

It will be appreciated that, where a transparency is desirably provided from film unit 70 of Figure 5, support 86 can be transparent and light-reflecting layer 84 omitted. In this case, a radiation-polymerizable composition of the invention will be applied to a suitable transparent support material and cured to the desired polymeric acid-reacting layer. The desired image in image-bearing layer 78 can then, upon separation of image-receiving element 86a from photosensitive element 72a, be viewed as a positive transparency through transparent support material 86.

The film units illustrated in Figures 3 to 5 have, for convenience, been shown as monochrome films.

Multicolor images may be obtained by providing the requisite number of differentially exposable silver halide emulsions, and said silver halide emulsions are most commonly provided as individual layers coated in superposed relationship. 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 having spctral 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 contains blue-, green-, and red-sensitive silver halide layers each having associated therewith in he same or in a continuous layer a yellow, a manenta and a cyan image dye-providing material, respectively.

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; and (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 or 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 materi and their application in color diffusion transfer, mention may made of those disclosed, for example in U.S. Patent Nos. 2,7742,968,554; 2,983,606; 2,087,817; 3,185,567; 3,230,082; 3,345,16 and 3,443,943. As examples of initially non-diffusible material and their use in color transfer systems, mention may be made of the materials and systems disclosed in U. S.

Patent Nos. 3,185, 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 U. S. Patent No. 3,647,437 to which reference may be made.

The acid-reacting polymeric layers of the invention possess a number of properties of particular use in photographic diffusion transfer products and processes. As discussed hereinbefore, such layers are of principle value in permitting predetermined control of environmental pH within a diffusion transfer process.

Thus, the acid-reacting polymeric layers of the invention can be employed in a diffusion transfer film unit and process utilizing image-forming dye developers to lowerthe environmental pH following substantial dye transfer. Desirably, the action of the acid-reacting polymeric layer will be controlled in a manner as not to interfere with either development of the negative or transfer of unoxidized dye developer. For this reason, the pH of the image-receiving layer will be kept at a pH level of from 12 to 14 until the positive dye image has been formed and will be rapidly reduced to a pH of less than 11,and usually to a pH of from 5 to 8.

The acid-reacting polymeric layers of the invention, in addition to the aforesaid advantages, are characterized by adherence to the support material to which they are bonded and relative freedom from defects in the nature of reticulation or "lacing". Such reticulation, believed to be attributable to differential swelling, is evident upon swelling of the polymeric acid-reacting layer as the result of permeation of the polymer layer by an aqueous alkaline processing composition as is commonly employed in photographic diffusion transfer processing.While applicants do not wish to be bound by any precise theory in explanation of polymer film reticulation, it is believed that such reticulation is the result of non-uniform or discontinuous polymer swelling such that a network or reticulation of swelled polymer is observed within expansive areas of polymer film having greater wet strength and resistance to swelling. By the present invention, acid-reacting polymeric film having uniform physical characteristics and free of such reticulation defects can be prepared.

The utilization of a comonomeric acrylic or methacrylic acid ester in the copolymerizable compositions utilized herein provides additional advantages in reducing the loss of acid-reacting monomer volatiles, fouling of the irradiation chamber or equipment and attenuation of the ion beam resulting from vapors of acid-reacting monomer. Dilution of the acid-reacting monomer with a nonvolatile acrylate or methacrylate ester in the manner of the present invention effectively reduces volatility of the resulting copolymerizable mixture, reduces the exotherm of the polymerization system and results in a net reduction of monomer losses.

The following examples are illustrative of the present invention and it will be understood that the invention is not limited thereto. All parts and percentages are by weight, except as otherwise indicated.

Example I A polyester sheet material having a radiation-polymerized acid-reacting layer bonded thereto was prepared in the following manner. A series of runs was conducted utilizing pieces of four-mil (0.1 Omm.)gelatin-subbed polyester film base (ethylene glycol terephthalate) onto which was coated, with the aid of a wire-wound coating rod, a layer of radiation-polymerizable composition. The radiationpolymerizable composition comprised, in the case of control Samples 1 to 3, acrylic acid (AA), and in the case of Samples 4 to 8, a mixture of acrylic acid (AA) and an acrylate ester, benzyl acrylate (BA) or 2-phenoxyethyl acrylate (PEA) in the molar proportions indicated in TABLE 1.In each instance, the amount of radiation-polymerizable composition coated onto the polyester support sheet is set forth in TABLE 1 as coverage in gms./ft2, and parenthetically, in gms./m2. The coated pieces of polyester sheet were subjected to polymerizing irradiation by passing the pieces, on a carrier web traveling at a rate of 18 ft./min (5.5m./min), beneath a source of ionizing irradiation of a dose expressed in TABLE 1 in megarads, wherein reference to "2 + 2" denotes two passes, each at a dose of two megarads. In each Sample, the coated polyester pieces were subjected after coating of the radiation-polymerizable composition to an inerting atmosphere of nitrogen so as to maintain the monitored level of oxygen below a concentration of 500 ppm.The radiation employed was a curtain of ionizing irradiation from a wire-filament electron source, available as the Electrocurtain system from Energy Sciences, Inc., Woburn, Massachusetts. The electron beams for the wire-filament source were passed through a beam window in the shielding cylinder and onto the continuously advancing coated pieces, placed on the carrier web, so as to effect polymerization of the coating.

The sheet material containing the bonded layer of acid-reacting acrylic acid/acrylate ester copolymer was, in each instance where reported, evaluated for content of water-soluble acid and neutralization speed. The results of these evaluations, reported in TABLE I, were obtained in the following manner.

Water-soluble acid content was determined by placing a sample piece of sheet material containing the bonded layer of acrylic acid/acrylate ester copolymer in a 500 ml. beaker containing distilled water and stirring for two hours. The size of each sample tested was six square inches (38.7 cm2). The water, containing dissolved acid from the sample piece, was titrated with standardized 0.1 N potassium hydroxide solution.

The amount of alkali consumed by titration is expressed in milliequivalents. By comparison of the amount of alkali consumed with the milliequivalents of acidity present in the test sample, and set forth in TABLE I as milliequivalents of acidity per square foot, the percentage of residual acidity in the sample may be expressed and is reported in TABLE The speed of the test samples in the neutralization of alkali from an alkaline processing composition was determined by observation of color change of an alizarin indicator dye in the alkaline processing composition. Each test sample was superposed in sandwich-like fashion on a transparent element comprising a cellulose triacetate film base having a coating of cross-linked gelatin at a coverage of 300 mgs/ft2 (3229 mgs/m2).An aqueous alkaline processing composition having a pH of about 14 and including alkaline potassium hydroxide, carboxymethyl hydroxyethyl cellulose thickening agent, benzotriazole, and an indicator dye (alizarin) undergoing a color change at about pH 8, was spread at a 0.003 in. (0.076 mm.) gap between the superposed elements in sandwich-like fashion as aforesaid described.The time measured in seconds, for the sandwich to start to change color from blue to pink, was recorded (Start) and the time for completion of the color change (Finish) was also measured and reported in seconds in TABLE l: TABLE 1 Wet Sample Composition Coverage* Dose Start/Finish Total Acidity** Residual Water No. (Mol. %) (g./ft) (Megarads) (secs) (Meq H+/ft) Soluble Acid (wt.%) 1 100 AA 1.96 (21.1) 4 10/10 23.2 (250) 20.3 2 100 AA 1.84 (19.8) 2 10/22 21.9 (236) 21.9 3 100 AA 1.49 (16.0) 1 5/12 20.5 (221) 24.4 4 83.7AA/16.3BA 1.87 (20.1) 2 12/26 16.8 (181) 4.8 5 68.8AA/31.2BA 1.80 (19.4) 2 + 2 15/90 8.5 (91.5) 0 6 48.6AA/51.4BA 1.77 (29.8) 2 + 2 40/175 6.8 (73.2) 0 7 85.4AA/14.6PEA 1.59 (17.1) 2 15.26 15.1 (163) 4 8 71.5AA/28.5PEA 2.21 (23.8) 2 + 2 30/80 12.0 (129) 0 9 51.9AA/48.1PEA 1.94 (20.9) 2 + 2 50/ 4.1 (44.1) 0 * parenthetical data in g./m ** parenthetical data in meq./m As can be seen from inspection of the data presented in TABLE I, the sheet materials of Samples 4 to 9 having a bonded layer of acrylic acidlacrylate ester copolymer exhibited acid-reacting functionality in the neutralization of alkali from an alkaline processing composition.In addition, the articles of Samples 4 to 9, compared to the control articles of Samples 1 to 3, exhibited lower levels of water-soluble acidity.

Example II Samples of polyester sheet material having bonded thereto an acid-reacting acrylic acid/acrylate ester copolymerwere prepared utilizing the materials and procedure and apparatus described in EXAMPLE I except that cyclohexyl acrylate (CHA) was utilized as the acrylate ester comonomeric material. Speed of neutralization was not measured. The results of the evaluation of such articles are shown in TABLE II as follows: TABLE II Wet Run Composition Coverage* Dose Total Acidity** Residual Water No. (Mol. %) (g./ft2) (Megarads) (meq. H+/ft2) Sloluble Acid(Wt.%) 10 83.3AA/16.7CHA 1.95(21.0) 2 + 2 18.34(197.4) 1.9 11 68.1AA/31.9CHA 2.09(22.5) 2 13.97(150.4) 2.0 12 47.8AA/52.2CHA 2.50(26.9) 2 10.23(110.1) 2.1 * parenthetical data in g./m2 ** parenthetical data in meq./m2 From the date set forth in TABLE II, it can be seen that the articles of Samples 10 to 12 exhibited low tevels of water-soluble acidity.

Example /// Samples of polyester sheet material having an acid-reacting acrylic acid/acrylate ester copolymer were prepared utilizing the materials, procedure and apparatus described in EXAMPLEI, except that isobornyi acrylate (IBA) and dicyclopentadienyl acrylate (DCPDA) were utilized as the acrylate ester comonomeric material. Speed of meutralization was not measured. The results of the evaluation of the articles of EXAMPLE I@I are setforthin TABLE I@I TABLE III Wet Run Composition Coverage* Dose Total Acidity** Residual Water No. (Mol. %) (g./ft) (Megarads) (meq.H+/ft) Soluble Acid (wt. %) 13 87.1AA/12.9 IBA 2.63 (28.3) 2 25.0 (269) 1.19 14 74.3AA/25.7 IBA 2.55 (27.4) 2 17.4 (187) 1.10 15 55.3AA/44.7 IBA 2.51 (27.0) 2 + 2 10.4 (112) 0 16 86.9AA/13.1 DCPDA 2.56 (27.6) 2 + 2 22.1 (238) 1.15 17 73.9AA/26.1 DCPDA 2.45 (26.4) 2 + 2 10.2 (110) 0.81 18 54.9AA/45.1 DCPDA 2.40 (25.8) 2 + 2 9.8 (105) 0 * parenthetical data in g./m ** parenthetical data in meq./m From the data set forth in TABLE Ill, it can be seen that the articles of Samples 13 to 18 exhibited low levels of water-soluble acidity.

Example IV Image-receiving elements having the structure generally shown in Figure 2 were prepared in the following manner. A series of runs was conducted utilizing pieces of four-mil (0.1 0mum) gelatin-subbed polyester film base (ethylene glycol terephthalate) onto which was coated, and with the aid of a wire-wound coating rod, a layer of radiation-polymerizable composition. The radiation-polymerizable composition comprised, in the case of control Sample 19, acrylic acid (AA), and in the case of Samples 20 to 29, a mixture of acrylic acid (AA) and an acrylate ester-2-phenoxyethyl acrylate (PEA), benzyl acrylate (BA), cyclohexyl acrylate (CHA) or tetrahydrofurfuryl acrylate (THFA) in the molar proportions indicated in TABLE IV. Each of the radiationpolymerizable compositions contained 0.25%, by weight of the composition, of Fluorad FC-430, a wetting agent.In each instance, the coated pieces of polyester sheet were subjected to polymerizing irradiation by passing the pieces, on a carrier web traveling at a rate of 20 ft./min. (6.1 ./min.) beneath a source of ionizing irradiation of a dose expressed in Table IV in megarads, wherein reference to "2 + 2" denotes two passes, each at a dose of two megarads, and wherein reference to "2+2+2" denotes three passes, each at a dose of two megarads. In the preparation of each Sample, the coated polyester pieces were subjected, after coating of the radiation-polymerizable composition, to an inerting atmosphere so as to maintain the monitored level of oxygen below a concentration of 500 ppm.The radiation employed was a curtain of ionizing irradiation from a wire-filament electron source, available as the Electrocurtain system from Energy Sciences, Inc., Woburn, Massachusetts. The electron beams from the wire-filament source were passed through a beam window in the shielding cylinder and onto the continuously advancing coated pieces, placed on the carrier web, so as to effect polymerization of the coating.

Each of the sheet materials containing the bonded layer of acid-reacting acrylic acid/acrylate ester copolymer (identified as Samples 19 to 29) were provided with a timing layer and an image-receiving layer.

In each instance, the timing layer was a 94:6 blend of a 60/30/4/6 tetrapolymer of butyl acrylate/diacetone acrylamide/styrene/methacrylic acid and polyvinyl alcohol coated with the aid of a wire-wound coating rod and dried for four minutes at 115 C in a circulating air oven. An image-receiving layer, a blend of 2 parts polyvinyl alcohol, one part poly-4-vinyl pyridine and one part of a graft of 4-vinyl pyridine and vinylbenzyltrimethyl ammonium chloride on hydroxyethyl cellulose, was coated onto each timing layer with the aid of a wire-wound coating rod and dried for three minutes at 1 000C. The ratios of the graft copolymer were as follows: 2.2 parts hydroxyethyl cellulose, 2.2 parts 4-vinyl pyridine and one part vinylbenzyltrimethyl ammonium chloride.

As a means for establishing a comparative reference, a control image-receiving element (identified as Sample 30) was prepared in the manner described in EXAMPLE IV except that, in lieu of the radiation-polymerized acid-reacting layer, an acid-reacting polymer layer was coated from solvent onto the polyester support and comprised nine parts of monobutyl ester of ethylene/maleic anhydride copolymer and one part polyvinyl butyral. Additionally, the polyester support material of the control image-receiving element was coated on the side opposing the acid-reacting layer with a quarter-wave anti-reflection coating of the type described in U. S. Patent 3,925,081.

In the following TABLE IV is set forth the nature of the image-receiving elements described in EXAMPLE IV.

TABLE IV Image-Receiving Polymerizable Element Composition Dose (Sample No.) (Mole %) (Megarads) 19 100%AA(Control) 4 20 85.4AA/14.6 PEA 4 21 71.5 AA/28.5 PEA 2+2 22 51.9AA148.1 PEA 2+2+2 23 83.7 AA/16.3 BA 2+2 24 68.8 AA/31.2 BA 2+2 25 83.3 AA/16.7 CHA 2+2 26 68.1 AA/31.9 CHA 2+2 27 48.5 AA/51.5 CHA 2+2 28 83.5 AA/16.5 THFA 2+2 29 68.4 AA/31.6 THFA 2+2 Example V Photographic diffusion transfer film units (A through L) utilizing the test and control image-receiving elements described in EXAMPLE IV were prepared in the following manner. A multi-color photosensitive element was placed in a superposed relation to each of the test and control image-receiving elements in the manner shown generally in Figure 3.After photoexposure under identical conditions, the film units were processed in the dark by passing the film units through mechanical spreading rolls at a 0.0032 inch (0.081 mm.) gap so as to rupture the marginal seal of a rupturable container and thereby uniformly spread the content of aqueous alkaline processing composition between the image-receiving and photosensitive elements.

The multicolor photosensitive element, using as cyan, magenta and yellow developers, the following compounds

yellow:

was a gelatin-subcoated three-mil (0.08mm) opaque polyethylene terephthalate film base having the following layers: 1. a layer of cyan dye developer, (4'-methyl-phenyl hydroquinone), and (2-phenyl benzimadole) dispersed in gelatin and coated at a coverage of about 69 mgs./ft2 (743 mgs./m2) dye developer, about 6.3 mgs./ft2 (67.8 mgs./m2) 4'-methyl-phenyl hydroquinone, about 25.1 mgs./ft2 (270 mgs./m2) or 2-phenyl benzimidazole and about 138 mgs./ft2 (1485 mgs./m2 of gelatin:: 2. a red-sensitive gelatino silver iodobromide emulsion coated at a coverage of about 120 mgs./ft2 (1292 mgs./m2) of silver and about 72 mgs./ft.2 (775 mgs./m2) of gelatin; 3. a layer of a 60-30-4-6 tetrapolymer of butylacrylate, diacetone acrylamide, styrene and methacrylic acid and polyacrylamide coated at a coverage of about 232 mgs./ft.2 (2497 mgs./m2) of the tetrapolymer and about 7.2 mgs./ft.2 (77.5 mgs./m2) of polyacrylamide; 4. a layer of magenta dye developer and 2-phenyl benzimidazole dispersed in gelatin and coated at a coverage of about 60 mgs./ft.2 (646 mgs./m2) of dye developer and about 42 mgs./ft2 (452 mgs./m2) of gelatin; 5. a green-sensitive gelatino silver iodobromide emulsion coated at a coverage of about 74 mgs./ft.2 (797mgs./m2) of silver and about 36 mgs./ft.2 (388 mgs./m2) of gelatin;; 6. a layer containing the tetrapolymer referred to above in layer 3, polyacrylamide and succinidialdehyde hardener coated at a coverage of about 127 mgs./ft.2 (1367 mgs./m2) of tetrapolymer, 1.8 mgs./ft.2 (87.2 mgs./m2) polyacrylamide and about 8.1 mgs./ft.2 (87.2 mgs./m2) of succinidialdehyde; 7. a layer of yellow dye developer and 2-phenyl benzimidazole dispersed in gelatin and coated at a coverage of about 90 mgs./ft.2 (969 mgs./m2) of dye developer, about 19 mgs./ft.2 (205 mgs./m2) 2-phenyl benzimidazole and about 42 mgs./ft.2 (452 mgs./m2 of gelatin; ; 8. a blue-sensitive gelatino silver iodobromide emulsion layer including the auxiliary developer 4'-methyl-phenyl hydroquinone coated at a coverage of about 119 mgs./ft.2 (1281 mgs./m2) of silver, about 62 mgs./ft.2 (667 mgs./m2) of gelatin and about 19 mgs./ft.2 (205 mgs./m2) of auxiliary developer; and 9. a layer of gelatin coated at a coverage of about 45 mgs./ft.2 (484 mgs./m2) gelatin.

The aqueous alkaline processing composition distributed from the rupturable container comprised the following ingredients: Ingredient Weight Percent Titanium dioxide 37.4 Carboxymethyl hydroxyethyl cellulose 1.90 Potassium hydroxide 5.26 Hydroxyethyl tricarboxymethyl ethylene diamine 0.75 Polyethylene glycol (Union Carbide Corporation, Carbowax 4000) 0.22 Benzotriazole 0.55 4-aminopyrazolo-(3,4d) pyrimidine 0.22 2-(benzimidazolyl methyl) sulfide 0.06 6-methyl uracil 0.70 3,5-dimethylpyrazole 0.20 N-phenethyl-a-picolinium bromide 1.27 3/1 mixture of Indathrone and Celanthrene Fast Pink 3B 0.06 Silicon dioxide colloidal suspension 0.55

Water Balance to 100 Following photoexposure and development of the film units described herein, Dmax and Dmin reflection density measurements were conducted and are reported as follows in TABLE V.

TABLE V Image Receiving Acid-Reacting Layer of D-Max D-Min Film Unit Element Image-Receiving Eiement R G B R G B A(Control) Sample=19 9Control) 100 mole %AA 1.67 1.52 1.38 .18 .18 .17 B Sample=20 85.4/14/6 mole %AA/PEA 1.70 1.53 1.66 .16 .17 .16 C Sample=21 71.5/28/5 mole %AA/PEA 1.63 1.50 1.83 .16 .17 .16 D Sample=22 51.9/48.1 mole %AA/PEA 1.83 1.67 1.75 .17 .19 .18 E Sample=23 83.7/16.3 mole %AA/BA 1.62 1.52 1.76 .18 .19 .18 F Sample=24 68.8/31.2 mole %AA/BA 1.76 1.62 1.75 .18 .19 .18 G Sample=25 83.3/16.7 mole %AA/CHA 1.62 1.48 1.75 .17 .18 .17 H Sample=26 68.1/31.9 mole %AA/CHA 1.69 1.54 1.75 .18 .19 .17 I Sample=27 48.5/51.5 mole %AA/CHA 1.92 1.68 1.57 .18 .19 .18 J Sample=28 83.5/16.5 mole %AA/THFA 1.58 1.50 1.87 .18 .19 .17 K Sample=29 68.4/31.6 mole %AA/THFA 1.85 1.68 1.65 .20 .21 .19 L Sample=30 (Control) Solvent-coated acidic polymer 2.03 1.77 1.80 .14 .18 .14 As can be seen from inspection of the Dmin and Dmax sensitometric results reported in Table V, acid-reacting layers prepared by the irradiation of radiation-polymerisable compositions as described herein were useful in diffusion transfer image-formation (Film units B through K).

Claims (37)

1. A product suitable for use in a photographic diffusion transfer process and comprising a sheet like support and an acid reacting polymer layer bonded to the support and formed by radiation polymerisation of a polymerisable composition comprising an aliphatic ethylenically-unsaturated carboxylic acid or an anhydride and an acrylate or methacrylate ester in a molar ratio of the acid or anhydride to the ester of from 0.5:1 to 15:1.

2. A product according to claim 1 in which the polymer layer has an acid reacting functionality in the range of 108 - 269 meq/m2.

3. A product according to claim 2 in which the polymeric layer has an acid reacting functionality in the range of 151-215 meq/m2.

4. A product according to any preceding claim in which the aliphatic ethylenically-unsaturated carboxylic acid has the formula R1 R O I I II R2-C =C-COH wherein R is hydrogen and R1 and R2 are each hydrogen or alkyl of from 1 to 3 carbon atoms.

5. A product according to claim 4 in which each R1 and R2 is hydrogen.

6. A product according to any preceding claim in which the molar ratio of the acid or anhydride to the ester is in the range 1.5:1 to 10:1.

7. A product according to any preceding claim also including an alkali solution permeable timing layer.

8. A product according to claim 7, comprising in order the support, the acid reacting layer and the timing layer.

9. A product according to any preceding claim also including an alkali solution permeable and dyeable image receiving layer.

10. A product according to claim 9, in which the image receiving layer is carried on the sheet support.

11. A product according to claims 8 and 10, comprising, in order, the support, the acid reacting layer, the timing layer and the image receiving layer.

12. A product according to claim 9, in which the image receiving layer is superposed to the acid reacting layer.

13. A product according to any of claims 1 to 12 also including at least one silver halide layer having associated therewith an image forming material.

14. A product according to claim 13, in which the at least one silver halide layer is carried on the support.

15. A product which is a photographic film unit for forming a diffusion transfer image comprising at least one sheet-like support; an image receiving emulsion layer; at least one photosensitive silver halide emulsion layer, each silver halide emulsion having associated therewith an image forming material; means for providing a processing composition for developing each silver halide emulsion after photo-exposure and for forming a diffusion transfer image in the image receiving layer; and bonded to at least one sheet-like support an acid reacting polymeric layer as defined in any of claims 1 to 6.

16. A product which is a photograhic film unitforforming a diffusion transfer image within a permanent laminate which comprises: a first sheet-like element comprising an opaque support carrying at least one photosensitive silver halide emulsion layer having associated therewith an image forming material; a second sheet-like element comprising a transparent support having bonded thereto an acid reacting polymeric layer as defined in any of claims 1 to 6 and carrying an image receiving layer comprising a dyeable and alkali solution permeable layer in superposed relation to the polymeric acid reacting layer; a rupturable container releasably holding an aqueous alkaline processing composition including a light reflecting pigment material; the first and second sheet-like elements being held in superposed fixed relationship with the supports outermost during photoexposure and processing and with the at least one silver halide emulsion layer being exposable through the transparent support; the rupturable container being positioned so as to release the processing composition for distribution between the sheet-like elements after photoexposure to provide a light reflecting layer of the pigment material, the light-reflecting layer providing a background against which the diffusion transfer image formed in the image receiving layer may be viewed through the transparent support without separation of the superposed first and second sheet-like elements.

17. A product which is a photographic film unit for forming a diffusion transfer image within a permanent laminate which comprises: a first sheet-like element comprising a first transparent support having bonded thereto an acid reacting polymeric layer as defined in any of claims 1 to 6; a second sheet-like element comprising a second support carrying, in sequence, an image receiving layer, a light reflecting layer comprising a light reflecting pigment material and at least one photosensitive silver halide emulsion layer, each silver halide emulsion layer having associated therewith an image forming material; a rupturable container releasably holding an aqueous alkaline opaque processing composition; the first and second sheet-like elements being held in superposed fixed relationship with said supports outermost during photoexposure and processing and with the at least one silver halide emulsion layer being exposable through the first transparent support; the rupturable container being positioned so as to release the aqueous alkaline opaque processing composition for distribution between the first and second sheet-like elements.

18. A product which is a photographic film unitforforming a diffusion transfer image comprising a photosensitive element comprising a support carrying at least one silver halide emulsion layer having associated therewith an image providing material; an image receiving element adapted to be separated from said photosensitive element after transfer image formation and comprising a support having bonded thereto an acid reacting polymeric layer as defined in any of claims 1 to 6, the acid reacting polymeric layer carrying an alkali permeable and dyeable image receiving layer; and, integrated with the photosensitive and image receiving elements, means for retaining a processing composition such that the processing composition can be distributed between the superposed elements after photoexposure of the photosensitive element.

19. A product according to any of claims 13 to 18 in which the image forming material is an image dye-providing material.

20. A product according to any preceding claim, in which the acrylate or methacrylate ester is a hydrocarbyl acrylate or methacrylate ester.

21. A product according to claim 20, in which the ester is an alkyl acrylate or methacrylate ester.

22. A product according to any of claims 1 to 19 in which the acrylate or methacrylate ester is an aryloxyalkyl acrylate or methacrylate ester.

23. A product according to claim 22, in which the aryloxyalkyl comprises phenoxyethyl.

24. A product according to claim 1 substantially as herein described.

25. A method for preparing a photographic product including an acid-reacting polymeric layer characterised by the steps of coating a sheet material with a radiation-polymerisable comonomeric mixture of an aliphatic ethylenically-unsaturated carboxylic acid or anhydride and an acrylate or methacrylate ester in a molar ratio of said aliphatic ethylenically-unsaturated carboxylic acid or anhydride to said acrylate or methacrylate ester of from about 0.5:1 to about 15:1 and subjecting the coating to radiation sufficient to polymerise the coating and bond it to the sheet material.

26. Method according to claim 25 wherein the radiation-polymerisable comonomeric mixture is coated onto said sheet material in an amount sufficient to provide said polymeric layer with an acid-reacting functionality in the range of from about 108 to about 269 meq./m2.

27. Method according to claim 26 wherein the radiation-polymerisable comonomeric mixture is coated onto the sheet material in an amount sufficient to provide the polymeric layer with an acid-reacting functionality in the range of from about 151 to about 215 meq./m2.

28. Method according to any of claims 25 to 27 wherein the radiation is at a dosage in the range of from about one to about ten megarads.

29. Method according to claim 28 wherein the dosage is in the range of from about two to about six megarads.

30. Method according to any of claims 25 to 29 wherein the radiation comprises ionising irradiation.

31.Method according to any of claims 25 to 30 wherein the aliphatic ethylenically-unsaturated carboxylic acid has the formula: R1 R O R2-C = C-COH wherein R is hydrogen and R1 and R2 are each hydrogen or alkyl of from 1 to 3 carbon atoms.

32. Method according to claim 31 wherein each of R1 and R2 is hydrogen.

33. Method according to any of claims 25 to 32 wherein the acrylate or methacrylate ester is a hydrocarbyl acrylate or methacrylate ester.

34. Method according to claim 33 wherein the ester is an alkyl acrylate or methacrylate ester.

35. Method according to any of claims 25 to 32 wherein said acrylate or methacrylate ester is an aryloxyalkyl acrylate or methacrylate ester.

36. Method according to claim 35 wherein the aryloxy-alkyl comprises phenoxyethyl.

37. Method according to any of claims 25 to 36 wherein the molar ratio of the acid or anhydride to the ester is in the range of from about 1.5:1 to about 10:1.