DE2910270A1 - Diffusion control layer for photographic diffusion transfer materials - comprises graft copolymer with grafted units of hydrophobic monomer and monomer capable of beta elimination in alkaline environment - Google Patents

Abstract

Photographic diffusion transfer prod. comprises a support with >=1 of (a) a photosensitive Ag halide emulsion layer with an associated processing compsn.-soluble, diffusible image-forming material; (b) a polymeric acid layer-and (c) an image-receiving layer, together with (d) a diffusion control layer comprising a graft copolymer (I). (II) has an organic polymeric backbone with grafted recurring units of (i) a hydrophobic monomer and (ii) units of a monomer capable of undergoing beta-elimination in an alkaline medium, of formula: R- CO- O- C(A)(E)- CH (D) (Y) (II). In (II), R is an ethylenically unsatd. 2-5 C alkyl gp., A, D and E are H, methyl or phenyl, provided that >1 of A, D and E is methyl or phenyl, and Y is an activating gp. (e.g. CN). The diffusion control layer controls premature migration of active materials in photographic multilayer diffusion transfer prods., e.g. to prevent premature migration of colour-providing materials during processing, which gives undesirable inter-image effects.

Description

The invention relates to photographic products for the manufacture

position of diffuse transfer images.

The main purpose of the invention is to create new layers for control diffusion in photographic diffusion transfer processes. These layers contain graft copolymers.

Another purpose of the invention is to create new image receiving elements, those especially for photographic diffusion transfer products and processes are suitable and which contain a graft copolymer Nateri al, the monomeric compounds, which are subject to ß-elimination in an alkaline environment, as well as hydrophobic ones Contains comonomers, each grafted onto an organic polymeric framework are.

Furthermore, according to the invention, new image receiving elements should in particular for color diffusion transfer photographic processes that represent composite structures. These composite structures contain a Carrier layer; a polymeric acid layer; one permeable to an alkaline solution Graft copolymer layer with special permeability properties; and a dyeable one polymeric image receiving layer.

Furthermore, according to the invention, a photosensitive element for photographic diffusion transfer methods are provided, that is, an intermediate layer or a top layer made of a graft copolymer material with predetermined permeability properties.

The invention also relates to a cover layer for an image receiving element, which is a graft copolymer material with monofunctional units that work in an alkaline medium subject to ß-limitation, as well as contains hydrophobic comonomer units, each of which is grafted onto an organic polymeric framework.

Other objects of the invention will emerge from the following Executions.

The invention is explained below with reference to the drawing. Show it: Fig. 1 is a section through a photographic film unit incorporating the invention Diffusion control layers; Fig. 2 is a section through an image receiving element with a retardation layer according to the invention for controlling the diffusion; and 3 shows a model arrangement for determining the "holding time" of the inventive Intermediate layers.

In the simultaneously filed patent application P (our reference: 3920-I-10.601) it is indicated that layers for controlling the diffusion in diffusion transfer film units, which from a state in which they are practically impermeable to alkalis or other reagents, in a state , in which they are practically permeable to these substances after ß-elimination, can be used as impermeable diffusion barriers to these substances until ß-elimination takes place. These polymers contain monomeric units which are subject to β-elimination under the influence of alkali and which have the structural formula where the symbols have the following meanings: R "is the addition polymerization product of an ethylenically unsaturated alkyl group with 2 to 5 carbon atoms, A, D and E are hydrogen, methyl or phenyl, with no more than one A, E or D being methyl or phenyl and Y is an activating group. Typical activating groups are: 0 0 -SO2W, -CT, -SG and -CN, where W = -C6H5CH3, -CH3, -OC2H5, -C6H5, -NR2, -N (CH2C6H5 ) 2; T is -OC2H5, -CH3, -H, -NH2, -NR2; G is phenyl, methyl or ethyl and R is methyl or ethyl.

It is indicated in the above-referenced patent application that Layers for controlling the diffusion from such polymerization products as Intermediate layers and top layers in photosensitive elements and as top layers and retardation layers suitable for controlling diffusion in image receiving elements are.

It was found that graft copolymers with monomeric units, which are subject to the ß-Elir.ainierunb and with hydrophobic comonomer units, which are grafted onto a polymeric framework as layers for controlling the Diffusion can be used in photographic diffusion transfer units can, especially in those units with which colored diffusion transfer images These graft copolymers have been found to be particularly useful are suitable in layers to control the diffusion in image capture elements, being a rapid transformation from a state in which the layers are opposite Alkali are practically impermeable, in a state in which they are practically permeable are done. These graft copolymers are also in the form of interlayers or Top layers in photosensitive elements or in the form of top layers in Image receiving elements useful for controlling diffusion.

In a preferred embodiment of the invention in which the graft copolymers used according to the invention in retardation layers of image receiving elements there may be minor fluctuations in the gap between the photosensitive Element and the image receiving element are balanced, the volume of the gap determines the amount of alkaline processing composition when the film unit develops will. The pH of the developer mass must be lowered to an excessive Transfer of the dye image-forming material to the image-receiving element impede. Furthermore, the retardation layer made of the graft copolymer enables that the alkalinity required to transfer the image dye is retained longer can become what is desired.

The graft copolymers used in the present invention become useful by grafting one or more monomer units onto a polymeric framework material, this in a manner known per se, with the formation of reactive sites for auto-fuming the monomeric compound (s) can be oxidized to the polymeric structure. For example, an ethylenically unsaturated monomer or a mixture of corresponding Comonomers expediently by means of an oxidation known per se with a transition metal ion catalyst on a polymeric framework material on ID qft.

It can all transition metal ion catalysts with a first Oxidation state, the oxidation potential of which in acidic solution is at least about 1 Volts when the transition metal to the next lower level is stable in solution Oxidation state is reduced, can be used for this purpose. As preferred Examples of catalysts are the transition metal ions V + 5, Ce 4 and Cr + 6.

With respect to the backbone polymer of the graft copolymer, generally all organic polymers are suitable repeating units with the grouping contain, where U is a hydroxyl, amino, amido, mercapto, acyl uder aroyl group, and which can be oxidized by a transition metal ion catalyst, as described above, provided that the graft copolymer obtained is on a suitable substrate can be applied to provide a barrier layer capable of transitioning from a relatively impermeable state to a relatively permeable state. The terms hydroxyl, acyl and aroyl used above also include the partial acetals of these special functional groups. Suitable builder polymers are polyvinyl alcohol, gelatin, hydroxyethyl cellulose, polyvinylpyrrolidone, polyacrylamide and the like. Preferred builder substances are polyvinyl alcohol and substituted or unsubstituted cellulose polymers such as hydroxyethyl cellulose that is used in the oxidation of the group assumes that free radicals are formed in the framework polymer, which attack the double bonds of the comonomers and in this way start the polymerization.

On the polymeric backbone is also a hydrophobic monomer or a Mixture of such monomers poured on. These monomers give it as a polymer Bulky copolymer to be applied has a certain hydrophobicity.

This hydrophobicity enables the desired control of the permeability properties of the graft copolymer.

Examples of useful hydrophobic ionomers are N-methylacrylamide; Methacrylamide; Ethyl acrylate; Butyl acrylate; Methyl methacrylate; N-methyl methacrylamide; N-ethyl acrylamide; N-methylolacrylamide; N, N-dimethylacrylamide; N, N-dimethyl methacrylamide; N- (n-propyl) acrylic? N-isopropyl acrylamide; N- (β-hydroxyethyl) acrylamide; N- (β-dimethylamino) acrylamide; N-t-butyl acrylamide; N- (β- (dimethylamino) ethyl) methacrylamide; 2- (2 '- (acrylamide) ethoxy) ethanol; N- (3'-methoxypropyl) acrylamide; 2-acrylamide-3-methylbutyramide; Acrylamidoacetamide; Methacrylamidoacetamide; 2- (2'-methacrylamido-3'-methylbutyramido) acetamide and diacetone acrylamide or mixtures thereof.

The graft copolymers used in the layers to control diffusion contain, as essential components, monomeric units from monomers which are subject to β-elimination in an alkaline medium and which have the formula given below: in which the symbols have the following meanings: R is an ethylenically unsaturated alkyl radical having two to five carbon atoms; A, E and D are hydrogen, methyl and phenyl, it being possible for no more than one A, E or D to be methyl or phenyl; and Y is an activating group.

Typical monomers that give their polymerization product a ß-eliminating Providing activating group are 2-cyanoethyl acrylate and 2-cyanoethyl methacrylate and 2-Oar 'ethoxyethyl methacrylate.

The graft copolymers according to the invention can contain additional units Contained from other ethylenically unsaturated monomers to specific and desirable Deliver properties. For example, compounds such as ethyl acrylate or 2-acrylamido-2-methylpropane sulfonic acid can be used to achieve a hydrophobicity-hydrophilicity balance to control the temperature range and the permeability during diffusion transfer to accomplish.

In accordance with the invention useful copolymers are for example: (1) acrylamide / diacetone acrylamide / β-cyanoethyl acrylate, a grafted on polyvinyl alcohol PVA / DAA / AA / CEA = 22/180/12/12 (parts by weight) (2) AcrylamidlDiac.eton.acrylamidJß-Cyanathylacrylat, grafted onto polyvinyl alcohol PVA / DAA / AA / CEA = 22/180 / 6J24 (parts by weight) (3) Diacetone acrylamide / ß-cyanoethyl acrylate, grafted onto polyvinyl alcohol PVA / DAA / OEA = 22/180/36 (parts by weight) (4) Acrylamide / diacetone acrylamide / ß-cyanoethyl acrylate, grafted onto polyvinyl alcohol PVA / DAA / AA / CEA = 22/180/12/24 (parts by weight) Other useful copolymers for layers to control diffusion in diffusion transfer photographic units are given below: (5) diacetone acrylamide / 8-cyanoethyl acrylate / 2-acrylamido-2 methylpropane sulfonic acid / ethyl acrylate grafted onto polyvinyl alcohol PVA / DAA / AMPS / EA = 22/180 / 1/12 (parts by weight) (6) diacetone acrylamide / ß-cyanoethyl acrylate / 2-acrylamido-2-methylpropane sulfonic acid / acrylamide, grafted onto polyvinyl alcohol PVA / DAA / CEA / AMPS / AA = 22/180/24/1 / 42 (parts by weight) (7) diacetone acrylamide / ß-cyanoethyl acrylate / 2-acrylamido-2-methylpropane sulfonic acid / acrylamide, grafted onto polyvinyl alcohol PVA / DAA / CEA / AMPS / AA = 22/180/24/116 (parts by weight) (8 ) Diacetone acrylamide / 2-acrylamido-2-methylpropane sulfonic acid / 8-cyanoethyl acrylate, grafted onto polyvinyl alcohol PVA / DAA / AMPS / CEA = 22/180/1/36 (parts by weight).

The abbreviations given above mean: PVA = polyvinyl alcohol; DAA - diacetone acrylamide; AA - acrylamide; CEA = β-cyanoethyl acrylate; AMPS = 2-acrylamido-2-methylpropane sulfonic acid; and EA = ethyl acrylate.

That used to prepare the graft copolymers of the invention β-eliminating monomer is used in such an amount as the graft copolymer the properties impart that it is made of a relatively impermeable State can pass into a relatively permeable state and so into acts as a diffusion control layer as described above. The amount of ß-eliminating monomer depends on the nature of the backbone polymer and the hydrophobic comonomers, their proportions and the respective and predetermined permeability properties of the layer for dispersing the Diffusion.

Generally, the β-eliminating monomer is used in such an amount used that the units of the monomer or monomers about 2 to about 30 Weight percent of the graft copolymer, preferably about 5 to about 25 weight percent. In a corresponding way, the hydrophobic units make the (s) ethylenic unsaturated monomer (s) from about 50 to about 90 weight percent of the graft copolymer.

Preferred graft copolymers are the graft products of β-eliminating Monomers and hydrophobic monomers based on polyvinyl alcohol. With these graft copolymers based on polyvinyl alcohol is a preferred β-eliminating mono.

mer the ß-Cyanäthylacrylat, while preferred hydrophobic monomers Diacetone acrylamide, alkyl acrylates such as ethyl acrylate and butyl acrylate as well as alkyl methacrylates, such as methyl methacrylate. These preferred graft copolymers produce the desired one Barrier layer that will be converted into a relatively permeable layer can, and are particularly suitable for coating on a surface where they dried simultaneously with several other layers of an image-receiving element can be. These graft copolymers also have a considerable temperature latitude as retardation layers, i.e. they give longer hold times at lower ones Temperatures, e.g., around 40C (400F), compared to the "hold times" at higher Temperatures, e.g. around 24 ° C (75 ° F).

The graft copolymers according to the invention, which in an alkaline medium subject to ß-elimination are suitable for delayed diffusion control in photographic film units for diffusion transfer. The ones from these Layers built up by graft copolymers to control the diffusion can be used as intermediate layers or cover layers in light-sensitive elements as well as control layers (e.g. Retardation layers or cover layers) are formed in image receiving elements. These polymeric substances must exposed to ß-elimination before significant swelling occurs, with ß-elimination and the swelling conditions are that certain substances in a aqueous alkaline developer liquid are soluble or made soluble by this will penetrate through them.

The ß-elimination of the polymers of the diffusion control layers are exposed according to the invention, ensures that after touching the DiffusiC "ns control layer through the developer the permeability is delayed, whereby the alkali or the soluble or solubilized material is retained; afterward a rapid release or opening follows, so that the soluble or solubilized Material can pass through. The polymers can be used as retention-release polymers be considered, which is the diffusion of alkali or substances present in the developer liquid are soluble or are made soluble by them, via a predetermined process Period, e.g.

from less than 5 seconds to more than a few hundred seconds, inhibit.

The mechanism by which the graft copolymers according to the invention undergo α-elimination in order to exhibit the desired "hold-release" effect can be illustrated with reference to the general scheme of β-elimination. By incorporating double bonds into a molecule with single bonds, atoms or groups of neighboring atoms are removed or eliminated. If elimination reactions occur with ß-substituted esters, acids, ketones, aldehydes and nitro compounds, these are referred to as ß-eliminations. According to Hendrickson, Cram and Hammond, Organic Chemistry (3rd edition, McGraw-Hill Book Company, 1970), the electron withdrawing groups have strong effects on the acid strength on the a-proton, which is removed by a base during the reaction. This 1,2-elimination under basic conditions is very common, as can be seen from FIG. 14-3 from Hendrickson, Oram and Hammond given below.

where L is a leaving group, B is a base and -NO2 is a typical activating group. In general, this equation can be stated as follows: wherein Y is an activating group.

Substituents that cause ß-elimination under basic conditions activate are known. The nature of the activation upon β-elimination has been suggested by J. Crosby and C.J.M. Stirling in J.Chem.Soc. (3) 1970, page 671 examined. Ss was found that resonance stabilization of a carbanion is an important component which is activating.

Such a ß-substituted compound can, I described above, be grafted onto a polymer to produce a polymer that is resistant to alkali or certain substances that are soluble in an alkaline developer composition or be solubilized thereby, is practically impermeable until through the ß-Elimination bonds are broken, whereby groups are released, which are able to absorb and swell water, so that the polymer for these soluble or solubilized substances become permeable; such a Polymer can be used in the form of a layer to control diffusion, wherein the predetermined delay is a premature diffusion of alkali or soluble or solubilized substances prevented. By setting the inolar Proportion or ratio of these β-elimination groups that are grafted onto the polymer are, as well as by the thickness of the polymer layer one can determine a predetermined Achieve permeability time as required for a particular diffusion transmission system is desirable.

With reference to the general equation for ß-elimination above, the ß-elimination scheme for a graft copolymer of polyvinyl alcohol, ß-eliminating monomer, and hydrophobic monomer (diacetone acrylamide = DAA) can be represented as follows: and R 'is, for example, hydrogen or methyl and Y is one of the groups -S02W, -CT, -SG or -CN, where W = 0 0 -C6H50H3, -CH3, -0C2H5, C6H5, -NR2, -N ( CH2C6H5) 2; T = -OC2H5, CH3, -H, NH2, -NR2; G = phenyl, methyl or ethyl and R is alkyl; B, A, E and D have the meanings given above.

The graft copolymers can be used in various diffusion transfer photographic processes be used in which an image-wise transfer of diffusible image-forming Material, e.g. of dyes, dye intermediates or soluble silver complexes, he follows. A particularly suitable system for the generation of color images by Diffusion transfer is described in US Pat. No. 2,983,606, wherein a developer dye is used as an imaging material. In such systems, a light-sensitive element with at least one silver halide layer to which a developer dye is assigned is dehydrated by the application of an aqueous-alkaline developer. That exposed and developable silver halide is developed by the developer dye, which in turn is oxidized to an oxidation product that is widely diffusible is considered to be the unreacted developer dye, causing an imagewise distribution of diffusible developer dye on the unexposed surface of the silver halide layer is produced; this uniform distribution is then at least partially due to diffusion transferred to a dyeable layer wherein a positive dye transfer image Multi-colored images can be obtained with a photosensitive element containing two or more selectively sensitized silver halide layers, to which developer dyes are assigned. A so-called "tripack" structure of this Type is described in numerous patents, particularly in the US patents 2 983 606 and 3 345 163.

In such color diffusion transmission systems, colored transmission images are produced obtained in the following way: a photosensitive element, sometimes called a negative component is designated and that at least one light-sensitive layer, e.g. Material in the same or an adjacent layer is exposed, to create a developable image. The exposed element is coated with a developer develops, with an imagewise distribution of a diffusible image dye-producing Material results. This image-wise distribution is at least partly due to diffusion on an overlying image-receiving layer, which is sometimes called the "positive component" and which contains at least one dyeable layer, transferred, whereby a colored transfer image is created. The negative and the positive Components can originally be attached to separate carrier layers, and are brought together during development and then separated from each other or held together as a finished integral negative-positive reflection image; she can also form a uniform structure right from the start, e.g. an integral one Negative-positive film unit in which the negative and positive components Form part of a photosensitive laminate. But you can also do this in other ways before, listening to and after the composition of the image are physically held one on top of the other. Film units for multicolored images contain two or more selectively sensitized silver halide layers, each of which is assigned a suitable image dye-generating material, the provide an image dye having spectral absorption properties essentially are complementary to the light through which the corresponding silver halide is exposed became. The most common negative components used to create multicolored Images have a "tripack" structure and contain blue, green and red sensitized Silver halide layers, each in the same or in an adjacent one Layer a yellow, purple, or blue-green image dye-generating material assigned. Between the corresponding silver halide layers and the associated ones Image dye-forming substances or between other layers can be intermediate layers or spacer layers made of the graft copolymers according to the invention may be arranged.

The image receiving layer can be built up from substances known per se e.g. made of polyvinyl alcohol, gelatin, etc.

They can be mordants or other means of fixing the transferred Contain image dyes. Changes the color of the transferred image dyes If the pH value is impaired, the pH value of the image layer can be adjusted that the desired color is created.

In the various known color diffusion transmission systems, in which an aqueous-alkaline developer is used, it is known to use a To use acidic storage reagent in one layer of the film unit, through which the pH of the environment is lowered after the dye has largely been coated will. This increases the image stability. Furthermore, in this way the pH of a first pH value at which the image dyes are diffusible, after a second (lower) pHT: Jert at which they are not diffusible, shifted will. For example, the aforementioned US Pat. No. 3,415,644 describes systems that in which the desired reduction in pH can be achieved, that a polymeric acid layer is provided adjacent to the dyeable layer is.

These polymeric acids can be polymers, they contain acidic groups, E.g. carboxylic acid and sulforic acid groups, which are mixed with alkalis or with organic Bases form salts. However, potential acid groups can also be used, e.g.

Anhydrides or lactones. Preferably the acidic polymer contains free ones Carboxyl groups. The acidic reacting reagent can, however, also be arranged in one layer that of the silver halide layer furthest from the image-receiving layer is adjacent.

Preferably, and are located between the polymeric acid layer the dyeable layer an inert intermediate layer or spacer layer around the Control or delay reduction in pH so that this does not occur prematurely occurs and disrupts the development process.

Although the acid layer and the associated spacer layer are preferred are contained in the positive component when the dyeable layer and the light-sensitive layer are contained on separate carrier layers (e.g. between the support layer for the image-receiving element and the dyeable layer), or in the integral film units of the dyeable Assigned to shift are (e.g. on the side of the dyeable If desired, they can also be assigned to the light-sensitive layers such as disclosed in U.S. Patents 3,362,821 and 3,573,043 is. In units of film as disclosed in U.S. Patents 3,594,164 and 3,594,165 they can also be included on the distribution film for better distribution of the Developing fluid is used.

In U.S. Patent 3,362,819, image receiving elements are described which are particularly suitable for diffusion transfer processes and the one carrier layer contain, on one side of which the following layers in the order given applied are: a polymeric acid layer; an inert retardation or spacer layer; and an image receiving layer for generating a visible image upon transfer of the diffusible dye image-forming substances on this layer.

The acidic polymer layer contains at least as many acid groups as that the pH of the image: receiving layer from about 12 to 14 after a certain Time is decreased to at least about 11, and preferably about 5 to 8.

It is of course necessary for the polymeric acid to act so it is controlled that neither the development of the negative nor the image transfer the non-oxidized developer dyes is disturbed. Because of this, the The pH of the image layer is kept at a value of about 12-14 until the positive Dye transfer image is built up, causing the pH to rise very quickly desired final value is reduced.

The inert spacer layer, a layer containing, for example, polyvinyl alcohol or contains gelatin, it contributes to the lowering of the pH by the polymer Acid layer to control in terms of a time delay. This delay depends on the speed with which the alkali passes through the inert spacer layer dii'i% 'nded.

If the alkali barrier layer (spacer layer) does not hold the alkali back a certain time, whereupon it suddenly lets it through, but lets the alkali through all ..; I'll seep through ", this is how the differences become in the case of shortened developments more pronounced in the maxi forest densities as a function of development time.

The use of the graft copolymers according to the invention in layers for diffusion control in diffusion transfer photographic units can be better explained with the aid of the drawing. As shown in Fig. 1, the layers according to the invention can be used to control diffusion in a photographic A unit may be used which includes a photosensitive member 26 and an image receiving member 27 contains. The intermediate layers 13 and 16 are located between the red and green sensitive resp.

between the blue- and green-sensitive silver halide emulsion in the photosensitive element. These interlayers and the emulsions with their associated dye-image-forming material, e.g. a developer dye, are preferably on a film pad / 10 in the order given below arranged: a layer 11 with a cyan developer dye, a red-sensitive one Silver halide emulsion layer 12, an intermediate layer 13, a layer 14 with a purple dye developer, a green-sensitive silver halide emulsion layer 15, an intermediate layer 16, a layer 17 with a yellow developer dye and a blue-sensitive silver halide emulsion layer 18. A top layer 19 from a graft polymer used according to the invention or from another polymer can be applied to the blue-sensitive silver halide emulsion layer.

The image receiving element of Fig. 1 contains in the order given an image receiving layer 21, a spacer or retardation layer 22, a neutralizing one Layer 23 and a Tgag layer 24. The image-receiving layer lies during development closest to the photosensitive element.

After exposure, the photosensitive element becomes an aqueous alkaline one Developer composition 20 between the photosensitive element and the image receiving element introduced; it penetrates the emulsion layers in order to develop the inside the latent image contained in it, and a medium for dye diffusion transfer to create the image receiving element. The dye image-forming substances that communicate with unexposed parts of the emulsion layers, diffuse in a manner known per se to the image receiving element, as indicated in US Pat. No. 3,362,819 there is a neutralizing layer under the image receiving layer, which contains a polymeric acid, through which the alkali in the developer composition is neutralized a predetermined time.

The delay or spacer layer of polymeric material that is arranged between the image receiving layer and the neutralizing layer, is used to control the reduction in pH. Layers to control diffusion, which contain the ß-eliminating graft copolymer according to the invention are at a preferred embodiment, the intermediate layers 13 and / or 16. In a further In a preferred embodiment, the spacer layer 22 can be a layer according to the invention to control diffusion through the graft copolymer.

The image receiving element 27 of FIG. 2 contains a carrier layer 28, a neutralizing layer 29, a spacer or retardation layer 30, a Image receiving layer 31 and an overcoat 32. During development the top layer of the image-receiving element is against the photosensitive element next. In one embodiment of the invention, the cover layer 32 is a layer to control the diffusion and contains the ß-eliminating graft copolymer according to the invention.

For multi-colored diffusion transfer products such as those above in which two or more silver halide layers are used, to each of which a dye image-forming material is assigned, a premature Migration of color-producing substances during development, undesirable inter-image effects cause the dye or other color-producing material at least is partly controlled by the lifalscheu silver halide layer, i.e. by a silver halide layer to which it was not originally assigned.

This problem can also be seen from a common "Tripack '" negative are explained with developer dyes, with the negative on a film base carries the following layers: a red-sensitive silver halide layer, which is an SSu-green Assigned to the developer dye, a green-sensitive silver halide layer, to which a purple developer dye is assigned, and a blue-sensitive one Silver halide layer to which a yellow developer dye is assigned. Ideally the solubilized developer dye should diffuse to its silver halide layer, and if it is not bound in this layer, it should continue into the image receiving element diffuse. Diffusion through the silver halide layer is generally controlled by the development of the silver halide layer. When the developer dye can migrate into other silver halide layers before its silver halide layer is developed, the resulting transfer image has due to loss of dye and / or transfer of the wrong dye does not achieve the desired color fidelity.

To explain these difficulties further: If the purple one Diffuse the developer dye back into the red-sensitive silver halide layer before this layer is developed by the cyan developer dye, karji part of the purple developer dye the silver halide in this one Develop the "wrong" layer and bind it there or make it non-diffusible will. This leads to a loss of purple dye, i.e. a so-called "Purple waste" in the transfer image. It also enables the development of the red-sensitive Silver halide layer by the purple developer dye that part of the blue-green developer dye, which should be oxidized, in the image: npfangselenent diffuses, resulting in undesirable cyan transfer.

In order to avoid or reduce these inter-image effects, you can Interlayers of graft copolymers, as described, in photosensitive Elements between the emulsions and their respective associated dye image-forming agents Substances are used. The ß-elimination that occurs in the graft copolymers of the Diffusion control layers according to the invention ensures that occurs after contact with the diffusion control layer by the developer, the permeability is delayed, whereby the soluble or solubilized material is initially retained will; this is followed by a quick release "or opening, so that the soluble or solubilized material can pass through the layer. The polymers can be viewed as cling-release '2 polymers that promote the diffusion of Substances that are soluble in or through the developer liquid are made to inhibit for a predetermined period of time. The time for ß-elimination after contact with the developer and for the subsequent hydration should be sufficient to provide the interlayer opposite the solubilized dye image-forming Keep material practically impermeable until the emulsion between the intermediate layer and the image receiving layer is at least largely developed, but before any significant obscuration of the emulsion layer with the largest Speed of obfuscation has occurred.

The layers according to the invention for controlling diffusion can used as intermediate layers between silver halide emulsion layers, sensitized to different areas of the spectrum, each with ~ '. emulsionXein is assigned dye imaging material. For example, you can use as described in U.S. Patents 3,615,422 and 3,421,892, wherein the "hold-on release" graft copolymers according to the invention instead of the interlayer polymers described there are used.

The ability of the graft copolymer layers according to the invention to Diffusion control to delay the passage of image-forming dyes, until the copolymer is relatively permeable to the dye through β-elimination can be determined using the test arrangement shown in FIG will. Here, on the transparent film carrier 33 of FIG. 3, a layer 34 with a blue-green dye developer, gelatin and a hardening agent such as cucchinaldehyde is applied using a conventional frame applicator will. A layer of the graft copolymer to be tested is applied to this layer. A transparent element 38 made from a polyester film backing is placed on top of this test element and an opaque alkaline developer, the titanium dioxide is inserted therebetween as shown in FIG. The optical one Reflection density against the red light of the test arrangement, through the film backing 33, can then be read continuously, with a MacBeth Quanta-Log densitometer can be used with a Hewlett-Packard 17505A recorder This density is made up of proportions of the in the dye layer bereaved dye image forming material and dye image forming material;: ateriais in the test shift. The titanium dioxide in the developer mass masks the dye-imaging agent Material in the layer of developer compound.

So by seeing the dye transfer through the polymeric test material followed, one can determine its "hold-release" properties, namely in analogy to the mode of action of this material, e.g. as an intermediate layer in one photosensitive element.

As stated earlier, the use of a graft copolymer layer represents a preferred one as a retardation or spacer layer in an image receiving element Embodiment of the invention. Such a layer is between the in the Diffusion transfer film unit introduced alkaline developer composition and a neutralizing layer, e.g., a polymeric acid layer, and it can effectively control the onset of pH lowering by acting as practically impermeable barrier for the alkaline developer composition acts until the ß-elimination takes place. The negligence properties of the here as retardation layers The graft copolymers used can expediently by measuring the "clearing time" under Can be determined using the method given below.

An image-receiving element comprising, in the order listed, a carrier layer, a polymeric acid layer, the retardation layer to be tested and a pickling layer contains, is made with an alkaline developer with a high pH value, which contains an indicator dye that stains strongly at pH values of about 12-14 and is colorless below about 10, coated. A transparent cover sheet laid. The view through the cover sheet to the image receiving element appears dark until the alkali has passed through the polymeric acid layer in which the pH is lowered by alkali consumption. This will the indicator dye is colorless and the system "clear". An experienced one Observer can determine when the "clearing" begins and when it is finished A leaky retardation layer leaves some alkali immediately after the first contact through and shows no sudden changes at the beginning and at the end of the clearing. A retardation layer with the graft copolymer according to the invention holds that Alkali returns a certain time and then allows for a very short period of time the passage of sufficient alkali to keep the pH below the transition range lower the indicator dye.

The clearing time can be determined for an arrangement that is a complete Represents image receiving element, or else for a simplified model arrangement, in which only a retardation layer on the polymeric acid layer on the Pad is applied. The first clarification period is called "clarification by the pickling agent" referred to, while the second clarification with the model arrangement as "clarification by the delay layer is counted.

In the following, the invention is non-restrictive by means of the examples Way explained.

Examples 1 to 4 There were four test elements by coating an approximately 0.1 mm (4 mil) thick polyethylene terephthalate film backing with a polymeric acid layer made, the 80 parts by weight of a polyvinyl methyl ether-maleic anhydride mers contained in a mixture with 20 parts by weight of polyvinyl alcohol; the layer thickness was about 0.025 mm (1 mil). Thereupon were the retardation layers indicated below applied: No. 1 A graft copolymer of diacetone acrylamide (180 Parts by weight) 2-cyanoethyl acrylate (12 parts by weight), 2-acrylamido-2-methylpropane sulfonic acid (1 part by weight) and ethyl acrylate (12 parts by weight) to 22 parts by weight of polyvinyl alcohol.

Kr. 2 A graft copolymer of diacetone acrylamide (180 parts by weight) 2-cyanoethyl acrylate (24 parts by weight), 2-acrylanido'2-methylpropane sulfonic acid (1 Part by weight) and acrylamide (12 parts by weight) to 22 parts by weight of polyvinyll alcohol.

No. 3 A graft copolymer of diacetone acrylamide (180 parts by weight) 2-cyanoethyl acrylate (24 parts by weight), 2-acrylamido-2-methylpropane sulfonic acid (1 Part by weight) and acrylamide (6 parts) to 22 parts by weight of polyvinyl alcohol.

No. 4 A graft copolymer of diacetone acrylamide (180 parts by weight) , 2-acrylamido-2-methylpropane sulfonic acid (1 part by weight) and 2-cyanoethyl acrylate (36 parts by weight) to 22 parts by weight of polyvinyl alcohol.

A standard element was made by relying on the the polymeric acid layer located on the film base applied a retardation layer which was 100 parts by weight of a 60/4/30/6 polymer of butyl acrylate / styrene / diacetonac Ryl amide / methacrylic acid contained in a mixture with 7 parts by weight of polyvinyl alcohol.

The polymer of the retardation layer No. 1 was prepared as follows: To a solution of 22 g (0.5 mol) of polyvinyl alcohol in 1 liter of distilled water 180 g (1.07 mol) of diacetone acrylamide, 12 g (0.10 mol) of 2-cyanoethyl acrylate and 1 g (0.005 mol) 2-AcrylSmido-2-methylpropane sulfonic acid added.

After the monomers dissolved, the pH of the solution became with concentrated nitric acid adjusted to 1.5. The solution was an hour with Nitrogen vented. After completion of the venting, 4.4 g of a surfactant was obtained (Triton X-100) added. The reaction was stirred until the surfactant was complete was resolved. Then there were 12 g (0.12 mol) of ethyl acrylate, which had previously been deaerated was added dropwise over a period of several minutes.

Then 4 g of cerium (IV) -X = monius nitrate in 20 ml of water were added and the polymerization was continued for 2 hours at room temperature. The transformation of the monomer into the polymer was greater than 98.5%.

The polymer of the retardation layer # 2 was prepared as follows: To a solution of 22 g (05 mol) of polyvinyl alcohol in 1 liter of distilled water 180 g (1.07 mol) of diacetone acrylamide, 12 g (0.17 mol) of acrylamide, 24 g (0.19 mol) 2-cyanathylacrylate and 1 g (0.005 mol) 2-acrylamido-2-IIIethylpropane sulfonic acid given. After dissolving the monomers, the pH of the solution was concentrated with Nitric acid adjusted to 1.5. The stirred solution was with nitrogen for one hour vented. After deaeration, 4.4 g of a surfactant (Triton X-100) was added. Stirring was continued until all of the surfactant had dissolved.

While nitrogen was passed over this solution, 4 g of cerium (IV) ammonium nitrate, dissolved in 20 ml of water, added to the stirred reaction solution. Then was still Stirred for a further 2 hours. The conversion of the monomer to the polymer was more than 28.5%.

The polymers of the retardation layers No. 3 and No. 4 were used in prepared in the same manner as the polymer of No. 2, with only the amounts of acrylamide and 2-cyanoethyl acrylate was varied On a transparent one Element in the form of a clear polyester film backing were the test elements as well laid the standard element, whereby laminated bodies were obtained. Then became a Developer compound with the composition given below between the test material layer and inserted the transparent element with the gap widths given below were used: 100 Lnl water 4.0 g Mydroxyäthyl-Carboxymethylcellulose 20.8 g 50% potassium hydroxide solution 1.1 g benzotriazole 0.5 g thymolphthalein.

The time (penetration time in seconds) after which the F @ of the composite changes from blue to colorless, is egg.

Measure of the time that the developer compound needs to create a retardation layer to penetrate and with the polymeric:., acid layer reducing the pH zu reagi: The times are referred to as the "beginning" when the stratified body is to clear-begins, and with "end" when the Schicil body is practically completely clear has become.

Clearing times (start, end), sec.

Gap width in mm standard example example example example (inch) 1 2 3 4 0.09 (0.0036) 180-265 585-665 61-69 120-137 83-114 0.07 (0.0028) 144-224 585-684 60-65 120-140 80-110 0.05 (0.0022) 103-203 610-697 N.M * N.M * N.M * 0.04 (0.0016) N.M * 60-66 122-139 80-106 * not determined The ones given above Values show the relative independence of the permeability values of the graft copolymers on the gap width (amount of the spread developer mass). Continue to show the values the relatively "leaky" nature of the standard bonding layers compared to the "hold-on release" properties of the retardation layers from the graft copolymers.

With handle 5 The following example shows the constancy of the invention Graft copolymer "hold-release" retardation layers as a function the alkali concentration, compared with the relative dependence of a usual one Retardation layer of fluctuating alkali content.

Test elements were made by coating a transparent polyethylene terephthalate film base (0.1 mm) with the following layers: 1. A polymer Acid layer made from 80 parts by weight of a polyvinyl methyl ether-maleic anhydride copolymer with 20 parts by weight of polyvinyl alcohol; Layer thickness about 0.025 mm (1 mil); and 2. a retardation layer with a graft copolymer of 180 parts by weight of diacetone acrylamide and 36 parts by weight of 2-cyanoethyl acrylate to 22 parts by weight of polyvinyl alcohol; Application weight approximately 5.38 g / m2 (500 mg / ft2).

Common comparisons were made by making a clear Polyethylene terephthalate film base two mm) with the layers indicated below was coated: 1. A polymeric acid layer at 80 parts by weight a polyvinyl methyl ether-maleic anhydride copolymer mixed with 20 parts by weight Polyvinyl alcohol; Layer thickness 0.025 mm (1 mil); and 2. a delay layer from a 60/30/4/6 / interpolymer of butyl acrylate, diacetone acrylamide, styrene and Methacrylic acid thickened with 7 -9 weight polyvinyl alcohol; Order weight approx 5, g / u2 (500 mg / ft2).

On a clear element made from a clear polyester film backing the test elements were placed to obtain laminates. An alkaline one Developer was placed between the polymer test material layer and the clear Element brought with the gap width was about 0.07 mm (0.002 pounds inch). The passage time was measured as in Examples 1-5.

For Experiment No. 5A, the alkaline one given below was used Developer compound used: 100 ml of water 4.0 g of hydroxyethyl carboxymethyl cellulose 4.2 g 5030 potassium hydroxide solution 1.1 g benzotriazole 0.5 g thymolphthalein.

For Experiment No. 5B, the alkaline one given below was used Developer compound used: 100 ml of water 4.0 g of hydroxyethyl carboxymethyl cellulose 20.8 g 50% potassium hydroxide solution 1.1 g benzotriazole 0.5 g thymolphthalein attempt Clearing time clearing time start (sec) end (sec.) 5A test 77 104 5A comparison o 9 5B test 30 110 5B Compare 144 224 This shows that the clearing time for the comparison element strongly depends on the alkali concentration, while the clearing time for the test elements with the graft copolymers according to the invention also at four times the amount of alkali Remaining surprisingly constant.

Examples 6 to 7 Image-receiving elements Eb and E7 and a standard, each on a clear polyethylene terephthalate film backing (0.1 mm) of a polymeric acid layer, a retardation layer and an image receiving layer (explained in more detail below).

E6 E7 Standard polymeric acid layer Ia Ia Ib retardation layer IIa IIa IIb Image receiving layer IIIa IIIb IIIa Here, Ia is a mixture of 80 Parts by weight of a polyvinyl methyl ether-maleic anhydride copolymer, mixed with 20 parts by weight of polyvinyl alcohol (layer thickness about 0.025 mm (1 mil); IIa is a graft copolymer made from diacetone acrylamide (180 parts by weight), acrylamide (6 Parts by weight), 2-cyanoethyl acrylate (24 parts by weight) and 2-acrylamido-2-methylpropane sulfonic acid (2 parts by weight to 22 parts by weight of polyvinyl alcohol; application weight about 5.38 g / m2 (500 mg / ft²). IIIa is a mixture of 2 parts by weight of polyvinyl alcohol, 1 part by weight of poly-4-vinylpyridine and 1 part by weight of a graft polymer 4-vinylpyridine and vinylbenzyltrimethylammonium chloride on hydroxyethyl cellulose (Ratios in graft polymer: I-hydroxyethyl cellulose 2.2, 4-vinylpyridine 2.2, Vinylbenzyltrimethylammonium chloride 1); Coating weight about 3.23 g / m² (300 mg / ft²); Ib is a polyvinylene / maleic anhydride copolymer mixed at 20 parts by weight Polyvinyl alcohol; Coating weight about 17.2 g / m (1600 mg / ft²); lib is a 4: 1 mixture a 60-30-4-6 tetrapolymer of butyl acrylate, diacetone acrylamide, styrene and methacrylic acid and polyvinyl alcohol; Coating weight is about 5,38 g / m² (500 mg / ft²); IIIb is a graft polymer of 4-vinylpyridine (2.2 parts by weight) and vinylbenzyltrimethylammonium chloride (1 part by weight) on hydroxyethyl cellulose (2.2 parts by weight), application weight about, 23 g / m² (300 mg / ft2).

The following developer compositions A and B were used: Developer composition A: 100 ml of water 4.0 g of hydroxyethylcarboxymethyl cellulose 20.8 g of 50% potassium hydroxide solution 1.1 g of benzotriazole 0.5 g of thymolphthalein developer composition B: 100 ml of water 4.8 g Hydroxyäthylcarboxymethylcellulose 25.7 g 45% potassium hydroxide solution 1.8 g benzotriazole 0.5 g 4-aminopyrazolo-3.4, D-pyramidine 0.5 g 5-methyluracil 0.? the connection 3.2g of the connection 1.9 g of ethylenediaminetetraacetic acid 0.05 g of bis (ß-aminoethyl) sulfide 1.2 g of high molecular weight polyethylene glycol 88.8 g of titanium dioxide 3.9 g of colloidal silica 5.7 g of N-phenethyl-α-picolinium bromide The clearing times were as in the examples 1 to 4 determined.

The times are given in the table below: Element developer composition Gap width time '(sec.) Start-end mm (inch) E6 A 0.07 (0.0023) 176-184 E6 A 0.05 (0.0022) 225-165 E7 A 0.07 (0.0023) 222-267 E7 A 0.05 (0.0022) 304-357 hours A 0.07 (0.0028) 180-222 hrs A 0.05 (0.0022) 138-173 E7 B G, 08 (0.0030) 223-272 hrs B 0.08 (0.0030) 199-424 The above values show the relative independence of the images catch elements according to the invention with the graft copolymers against fluctuations the gap width as well as the "hold-up release" properties of these graft copolymers compared to the "leaky" retardation layers of the standard image receiving element.

Examples 8 and 9 Two further test elements are produced, by placing a clear polyethylene terephthalate film base (0.1 mm) with a polymeric acid layer was coated, the 89 parts by weight of the half-butyl ester of the ethylene / maleic anhydride copolymer in a mixture with 11 parts by weight of polyvinyl butyral contained; Layer thickness about 0.05 mm (2 mils). The following retardation layers were then applied applied: Example 8: A graft copolymer of butyl acrylate (180 Parts by weight), 2-cyanathylacrylate (40 parts by weight), 2-acrylamido-2-methylpropane sulfonic acid (1 part by weight) to 22 parts by weight of polyvinyl alcohol.

Example 9: A graft copolymer of butyl acrylate at (90 parts by weight), Nethyl methacrylate (40 parts by weight), 2-cyanoethyl acrylate (20 parts by weight) 22 parts by weight of polyvinyl alcohol.

A second standard element (Std 2) was made by via the mixture of the half-butyl ester of the polymers on the film base Acid and polyvinyl butyral a retardation layer was applied, which is 100 parts by weight of a 60/40/30/6 polymer of butyl acrylate / styrene / diacetone acrylanide / methacrylic acid contained in a mixture with 7 parts by weight of polyvinyl alcohol.

The polymer of the retardation layer (Example 8) was prepared as follows: To a solution of 22 g (0.5 mol) of polyvinyl alcohol in 1 liter of distilled water 180 g (1.4 mol) of butyl acrylate, 40 g (0.32 mol) of 2-cyanoethyl acrylate and 1 g (0.005 mol) of 2-acrylamido-2-methylpropane sulfonic acid added. The pH of the mixture was adjusted to 1.5 with concentrated nitric acid. Then the mixture became deaerated with nitrogen for one hour. After venting was complete, 26 g a surfactant (Abex 265) added. The reaction mixture was stirred until the Surfactant was completely dissolved. Then 4 g of cerium (IV) ammonium nitrate in 20 ml of water was added and the polymerization was continued at room temperature for 2 hours. The conversion of the monomer into the polymer was more than 98.5 ° ó.

The polymer of the retardation layer according to Example 9 was made as follows manufactured: To a solution of 22 g (0.5 mol) of polyvinyl alcohol in 100 ml of distilled. Water was 90 g; (0.7 mol) butyl acrylate, 40 g (0.4 mol) Methyl methacrylate and 20 g (0.16 mol) of 2-cyanoethyl acrylate were added. The pH of the Mixture was adjusted to 1.5 with concentrated nitric acid. That touched Mixture was vented with nitrogen for one hour.

After the end of the venting, 15 g of a surfactant (Abex 265) admitted. Stirring was continued until the surfactant was completely dissolved. While While nitrogen was passed over the solution, 4 g of cerium (IV) ammonium nitrate were dissolved in 20 ml of water. Stirring was then continued for a further two hours. The transformation of the monomer in the polymer was more than 9E, 5 p.

The test elements (Examples 8 and 9) were made in the same manner as evaluated the test elements according to Examples 1 to 4, the following The results obtained were: clearances (start-end) sec.

Gap width, mm Standard Example 8 Example 9 (inch) 0.09 (0.0036) 255-307 500-710 120-210 0.07 (0.0028) 180-222 553-730 130-195 0.05 (0.0022) 138-173 601-748 140-195 The test elements (Examples 8 and 9) were made in the same manner evaluated as in Example 5, the following results being obtained: attempt Clearing time clearing time start (sec) end (sec) 5A test (example 8) 840 1380 5A comparison (Standard 2) 28 41 5A test (example 9) 208 368 5B test (example 8) 553 730 5B Comparison (Standard 2) 180 222 5B Test (Example 9) 1) "0 195 The above values show that the retardation layers with the graft copolymers according to the examples 8 and 9 develop remarkable "hold-on-release" properties and ability have to increase the penetration properties by changing the alkali concentration steer.

Claims (48)

Graft polymers as a layer for controlling diffusion in photographic products. PATENT CLAIMS L Photographic diffusion transfer film unit, comprising a) a photosensitive element with at least one photosensitive silver halide emulsion layer to which an image-forming material which is soluble and diffusible in a developer composition is associated; b) an image receiving element; c) means for distributing an alkaline developer composition in the film unit and d) a layer for controlling diffusion in the light-sensitive element and / or in the image-receiving element; characterized in that the layer for controlling the diffusion contains a core copolymer with an organic polymeric structure, on which recurring units of a hydrophobic monomer and recurring units of a monomer which is subject to β-elimination in an alkaline medium and which has the formula where the symbols have the following meanings: R is an ethylenically unsaturated alkyl radical with 2 to 5 carbon atoms; A, E and D are hydrogen, methyl and Phenyl, with no more than one A, E and D being methyl or or phenyl is; and Y is an activating group. 2. Film unit according to claim 1, characterized in that the photosensitive Element contains at least two silver halide emulsion layers, one of which is in assigned to a developer composition soluble and diffusible image-forming material and that the diffusion control layer is one between the silver halide emulsion layers represents arranged intermediate layer. 3. Film unit according to claim 1, characterized in that the layer represents a cover layer in the photosensitive element to control the diffusion. 4. Film unit according to claim 1, characterized in that the layer for controlling the diffusion in the image receiving element present in the image receiving element and is preferably a retardation layer or an overcoat of the image receiving element represents. 5. Film unit according to one of claims 1 to 4, characterized in that that the imaging material is a dye developer. 6. Film unit according to one of claims 1 to 5, characterized in that the activating group is one of the groups represents, in which the symbols have the following meanings: W is -C6H5CH3, -CH3, -OC2H5, -C6H5, -NR2, -N (CH2C6H5) 2; T is -OC2H5, -CH3, -H, -NH2, -NR2; G is phenyl, methyl or ethyl and R is methyl or ethyl. 7. Film unit according to one of claims 1 to 6, characterized in that that the monomer 2-cyanoethyl acrylate, 2-cyanoethyl methacrylate, which is subject to β-elimination or is 2-carbethoxyethyl methacrylate. 8. Film unit according to one of claims 1 to 7, characterized in that that the units from the monomer subject to β-elimination are about 2 to 30 Constitute weight percent of the graft copolymer. 9. film folder according to one of claims 1 to 7, characterized in that that the units of the hydrophobic monomer are about 50 to about 90% by weight of the graft copolymer turn off. 10. Film unit according to one of claims 1 to 9, characterized in that that the hydrophobic monomer diacetone acrylamide, an alkyl acrylate, an alkyl methacrylate or a mixture of these substances. II. Film unit according to one of Claims 1 to 10, characterized in that that the organic polymeric structure is a structure made of cellulosic polymers, vinyl polymers and / or gelatin. 12. Film unit according to claim 11, characterized in that the organic polymeric backbone represents polyvinyl alcohol. 13. A photosensitive element for diffusion transfer photographic processes comprising: a support layer; at least two selectively sensitized silver halide emulsion layers which are applied to the carrier layer, each emulsion layer being assigned an image-forming material which is soluble and diffusible in a developer composition; and an intermediate layer arranged between at least two silver halide emulsion layers, characterized in that the intermediate layer contains a graft copolymer with an organic polymeric skeleton, on which recurring units of a hydrophobic monomer and recurring units of a monomer which is subject to ß-elimination in an alkaline medium and which has the formula has, are grafted, in which the symbols have the following meanings: R is an ethylenically unsaturated alkyl radical having 2 to 5 carbon atoms; A, E and D are hydrogen, methyl and Phenyl, where no more than one A, E and 3 are methyl or or phenyl is; and Y is an activating group. 14. Photosensitive element according to claim 13, characterized in that that the imaging material is a dye developer. 15. Element according to claim 13 or 14, characterized in that the activating group is one of the groups represents, in which the symbols have the following meanings: W is -C6H5CH3, -CH3, -OC2H5, -C6H5; -NR2, -N (CH2C6H5) 2; T is -OC2H5, -CH3, -H, -NH2, -NR2; G is phenyl, methyl or ethyl and R is methyl or ethyl. 16. Element according to one of claims 13 to 15, characterized in that that the monomer 2-cyanoethyl acrylate, 2-cyanoethyl methacrylate, which is subject to β-elimination or is 2-carbethoxyethymethacrylate. 17. Element according to one of claims 13 to 16, characterized in that that the units from the monomer subject to β-elimination are about 2 to 30 Make up <% 'by weight of the graft copolymer. 18. Element according to one of claims 13 to 16, characterized in that that the units of the hydrophobic monomer are from about 50 to about 90 percent by weight of the graft copolymer turn off. 19. Element according to one of claims 13 to 18, characterized in that that the hydrophobic monomer diacetone acrylamide, an alkyl acrylate, an alkyl methacrylate or a mixture of these substances. 20. Element according to one of claims 13 to 19, characterized in that that the organic polymeric structure is a structure made of cellulosic polymers, vinyl polymers and / or gelatin. 21. Element according to claim 20, characterized in that the organic polymeric backbone is polyvinyl alcohol. 22. Photosensitive element for diffusion transfer photographic processes; comprising: a backing layer; at least one light-sensitive silver halide emulsion layer, which is applied to the carrier layer, wherein the emulsion layer in the Developer compound assigned to soluble and diffusible image-forming material is; and a top layer; characterized in that the top layer contains a graft copolymer with an organic polymeric backbone, repeating on the Units of a hydrophobic monomer and repeating units of a monomer, which is subject to ß-elimination in an alkaline medium and which has the formula O A D R-C-O-C-C-Y EH, are grafted, in which the symbols have the following meanings have: R is an ethylenically unsaturated alkyl radical with 2 to 5 carbon atoms; A, E and D are hydrogen, methyl and Phenyl, with no more than one A, 9 Iid D methyl or or phenyl is; and Y is an activating group. 23. Element according to claim 22, characterized in that the imaging M material is a developer dye. 24. Element according to claim 22 or 23, characterized in that the activating group is one of the groups represents, in which the symbols have the following meanings: W is -C6H5CH3, -CH3, -002H5, -C6H5, -NR2, -N (CH2C6H5) 2; T is -0C2H5, -CH3, -H, NH2 'NR2; G is phenyl, methyl or ethyl and R is methyl or ethyl. 25. Element according to one of claims 22 Dis 24, characterized in that that the monomer 2-cyanoethyl acrylate, 2-cyanoethyl methacrylate, which is subject to β-elimination or is 2-carbethoxyethyl methacrylate. 26. in element according to one of claims 2, oi..s 25 characterized that the units from the monomer subject to β-elimination are about 2 to 30 Make up by weight 'of the graft copolymer 27. Element according to any one of claims 22 bi 25, characterized in that the units of the hydrophobic monomer are about 50 constitute up to about 90 percent by weight of the graft copolymer. 28. Element according to one of claims 22 to 27, characterized in that that the hydrophobic monomer Diacetonacrylami d, an alkyl acrylate, an alkyl methacrylate or a mixture of these substances. 29. Element according to one of claims 22 to 28, characterized in that that the organic polymeric structure is a structure made of cellulosic polymers, vinyl polymers and / or gelatin. 30. Element according to claim 29, characterized in that the organic polymeric backbone is polyvinyl alcohol. 31. A photographic film unit in the form of a combination of a photosensitive member and an image receiving member for diffusion transfer, comprising: a support layer; at least two selectively sensitized silver halide emulsion layers which are applied to the carrier layer, each emulsion layer being assigned an image-forming material which is soluble and diffusible in a developer composition; an intermediate layer disposed between at least two silver halide layers; and an image-receiving layer which is permeable to an alkaline developer and can be dyed, characterized in that the intermediate layer contains a graft copolymer with an organic polymer backbone on which recurring units of a hydrophobic monomer and recurring units of a monomer which is subject to ß-elimination in an alkaline medium and which has the formula has, are grafted, in which the symbols have the following meanings: R is an ethylenically unsaturated alkyl radical; a with 2 to 5 carbon atoms; A, E and D are hydrogen, methyl and Phenyl, with no more than one A, E and D being methyl or or phenyl is; and Y is an activating group. 32. Film unit according to claim 31, characterized in that the imaging material is a dye developer. 33. Film unit according to claim 31 or 32, characterized in that the activating group is one of the groups represents, in which the symbols have the following meanings: W is -C6H5CH3, -CH3, -OC2H5, -C6H5, -NH2, -N (CH2C6H5) 2; T is -OC2H5, -CH3, -H, -NH2, -NR2; G is phenyl, methyl or ethyl and R is methyl or ethyl. 34. A film unit according to any one of claims 31 to 33, characterized in that that the monomer 2-cyanoethyl acrylate, 2-cyanoethyl methacrylate, which is subject to β-elimination or is 2-carbethoxyethyl methacrylate. 35. Film unit according to one of claims 31 to 34, characterized in that that the units as Us of the monomer subject to β-elimination are about 2 to 30 Constitute weight percent of the graft copolymer. 36. Film unit according to one of claims 31 to 34, characterized in that that the units of the hydrophobic monomer are from about 50 to about 90 percent by weight of the graft copolymer turn off. 37. Film unit according to one of Claims 31 to 36, characterized in that that the hydrophobic monomer diacetone acrylamide, an alkyl acrylate, an A1kyl'ethacrylat or a mixture of these substances. 38. Film unit according to one of claims 31 to 37, characterized in that that the organic polymeric structure is a structure made of cellulosic polymers, vinyl polymers and / or gelatin. 39. A film unit according to claim 38, characterized in that the organic polymeric backbone is polyvinyl alcohol 40. An element for photographic diffusion transfer processes, comprising: a support layer; a polymeric acid layer; and a further polymeric layer, characterized in that the further polymeric layer contains a graft copolymer with an organic polymeric structure on which recurring units of a hydrophobic monomer and recurring units of a monomer which is subject to β-elimination in an alkaline medium and which has the formula has, are grafted, in which the symbols have the following meanings: R is an ethylenically unsaturated alkyl radical having 2 to 5 carbon atoms; A, E and D are hydrogen 'methyl and Phenyl, with no more than one A, E and D being methyl or or phenyl is; and Y is an activating group. 41. Element according to claim 40, characterized in that there is a contains alkali-permeable and dyeable image-receiving layer. 42. Element according to claim 40 or 41, characterized in that the activating group is one of the groups represents, in which the symbols have the following meanings: W is -C6H5CH3, -CH3, -OC2H5, -C6H5, -NR2, -N (CH2C6H5) 2; T is -OC2H5, -CH3, -H, -NH2, -NR2; G is phenyl, methyl or ethyl and R is methyl or ethyl. 43. Element according to one of claims 40 to 42, characterized in that dä3 the monomer 2-cyanoethyl acrylate, 2-cyanoethyl methacrylate, which is subject to β-elimination or is 2-carbethoxyethyl methacrylate. 44 Element according to one of Claims 40 to 43, characterized in that that the units from the monomer subject to 3-elination are about 2 to 30 Constitute weight percent of the graft copolymer. 45. Element according to one of claims 40 to 43, characterized in that that the units of the hydrophobic monomer are from about 50 to about 90 percent by weight of the graft copolymer turn off. 46. Element according to one of Claims 40 to 45, characterized in that that the hydrophobic monomer diacetone acrylamide, an alkyl acrylate, an alkyl methacrylate or a mixture of these substances. 47. Element according to one of claims 40 to 46, characterized in that that the organic polymeric structure is a structure made of cellulosic polymers, vinyl polymers and / or gelatin. 48. Element according to claim 47, characterized in that the organic polymeric backbone is polyvinyl alcohol.