US3043692A - Photographic products and processes - Google Patents

Description

July 10, 1962 H. c. I-IAAs ET AL 3,043,692

PHOTOGRAPHIC PRODUCTS AND PROCESSES Filed Dec. 17, 1958 SILVER HALIDE EMULSION LAYER P-ACETAMIDOBENZENE SULFONATE OF A PARTIAL O-SODIUM SULFOBENZAL OF POLYVINYL ALCOHOL CONTAINING A OLOR-PROVIDING SUBSTANCE BLUE-SENSITIVE SILVER HALIDE EMULSION LAYER P-ACETAMIDOBENZENE SULFONATE OF A PARTIAL O-SODIUIVI SULFOBENZAL OF POLYVINYL ALCOHOL CONTAINING A 36 YELLOW DYE DEVELOPER T RLAYER GREEN-SENSITIVE sILvER HALIDE MULSION LAYE 0- \{P-ACETAMIDOBENZENE SULFONATE OF A as PARTIAL O-SODIUM SULFOBENZAL OF POLYVINYL ALCOHOL CONTAINING A 26 T MAGENTA DYE DEVELOPER XX 24 \{lNTERLAYER 22 RED-sENsITIvE SILVER HALIDE EMULSION LAYER- 20 P-ACETAMIDOBENZENE SULFONATE OF A PARTIAL O-SODIUM SULFOBENZAL OF POLYVINYL ALCOHOL CONTAINING A cYAN DYE DEVELOPER SUPPORT FIG.2

' INVENTORS MQ.M

United rates The present invention is concerned with photography and more particularly with novel photographic products and novel photographic processes utilizing said products.

One object of thisinvention is to provide novel photosensitive elements for color diffusion transfer processes comprising at least one silver halide emulsion layer and at least one layer of a polymeric material having a colorproviding substance disposed therein, said polymeric layor being an acylamidobenzene sulfo ester of a partial sulfobenzal of polyvinyl alcohol.

Another object of this invention is to provide improved color diffusion transfer processes utilizing said photosensitive elements.

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

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

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

FIGURE 1 is a diagrammatic cross-sectional view of one embodiment of a photosensitive element of this invention; and

FIG. 2 is a diagrammatic cross-sectional view of one embodiment of a multilayer photosensitive element within the scope of this invention.

The present invention is particularly related to color diffusion transfer processes. In such processes a photosensitive element including a silver halide emulsion layer is exposed to create therein a latent image. The latent image is developed and, concurrent with and under the control of this development, an imagewise distribution of mobile color-providhrg substances is formed. At least aportion of these color-providing substances is transferred by means of an alkaline aqueous processing liquid to a superposed image-receiving layer to form a color image thereon. As examples of such processes, mention may be made of the processes disclosed and claimed in the copending U.S. application of Howard G. Rogers, Serial No. 748,421, filed July 14, 1958, as a continuation-in-part of U.S. application, Serial No. 415,07 filed March 9, 1954, and now abandoned, said continuation-impart application now U.S. Patent 2,983,606 issued May 9, 1961, wherein dye developers (i.e., compounds which contain in the same molecule both the chromophoric system of a dye and also a silver halide developing function) are the colorsproviding substances, the processes claimed and disclosed in U.S. Patent No. 2,647,049, issued July 28, 1953,

to Edwin H. Land, wherein color developers are employed to develop the latent image and color couplers are the color-providing substances, and the processes dis- In an especially useful mode of carrying out color diffusion transfer processes such as described above, the color-providing substances are disposed in a separate alkali-permeable layer in the photosensitive element. The separate alkali-permeable layer may be placed either in front of or behind the photosensitive emulsionwith which it is associated; however, in a preferred embodiment it is placed behind, i.e., on the side of the emulsion which is most distant from the photographed subject when the emulsion is exposed, and preferably also adapted to be most distant from the image-receiving element when in superposed relationship therewith. In carrying out the processes, the photosensitive element is exposed and wetted with an aqueous alkaline processing solution, for example, by immersing, coating, spraying, flowing, etc., in the dark, and the photosensitive element is superposed prior to, during or after wetting on an image-receiving element. In a preferred embodiment the aqueous alkaline processing solution contains a viscosity-increasing compound andis applied to the photosensitive element in a substantially uniform layer asthe photosensitive element is brought into superposed position with the image receiving element. The alkaline aqueous processing solutionpermeates the photosensitive emulsion and alkali permeable layers and solubilizes the color-providing substances to provide a substantially uniform distribution of the color-providing substances therein. As the processes proceed, the exposed silver halide image is developed and an imagewise distribution of mobile color-providing substances is formed. At least a portion of the color-providing substances is transferred to and imbibed on the image-receiving element to form the image there on. The image is viewed by stripping the image-receiving element from the photosensitive element.

When the color-providing substances are incorporated into a separate alkali-permeable layer, it is desirable that said alkali-permeable layer have good dry adhesion to the other layers present in order to withstand the stresses and strains such a layer would be normally subjected to during, for example, coating operations, and especially to withstand the stresses and strains which are encountered if the photosensitive element is a part of a roll film unit. Such adhesion must be achieved in the presence of relatively high amounts of the color-providing substances which generally have little or no adhesiveness in themselves and which often have an adverse effect on the bonding. It is furtherdesirable, and no less important, that said alkali-permeable layers have good wet adhesion to the other layers present; otherwise, during processing, upon stripping the image-receiving element.

from the photosensitive element, delamination may take place and portions of the photosensitive element would adhere to the surface of the image-receiving element and mar the quality of the transfer image. #It is still further desirable that the alkali-permeable layer readily release the color-providing substances in order to make the maxi? mum amount of said materials available for forming the positive image. In the past, film-forming polymers such, for example, as cellulose acetate hydrogen phthalate have been proposed as materials for the alkali-permeable layers.

It has been discovered that when the colorrproviding substances are disposed in polymeric layers comprising the acylaminobenzene sulfo esters of partial sulfobenzals of polyvinyl alcohol, such polymers provide wet and dry adhesion which is superior to that obtained with cellulose acetate hydrogen phthalate, and, further, said polymers readily release the color-providing substances.

The ability of the polymers of this invention to release the color-providing materials is especially demonstrable when dye developers are the color-providing materials,

contain in the same molecule both the chromophoric system of a dye and also a silver halide developing function. By a silver halide .developing function is meant a radical which is capable of developing an exposed silver halide image. Particularly useful dye developers are those in which the silver halide developing function is provided by a benzenoid developing radical. A preferred benzenoid developing radical in such compound is a hydroquinonyl group. Examples of representative dye developers are given in the previously mentioned US. application of Howard G. Rogers, Serial No. 748,421. Additional useful dye developers are described in the following copending US. applications:

Application Serial No. 449,514, filed August 12, 1954, in

' the names of Elkan R. Blout and Myron S. Simon.

Application Serial No. 471,542, filed November 26, 1954, in the names of Elkan R. Blout, Saul G. Cohen, Milton Green, Howard G. Rogers, Myron S. Simon and Robert B. -Woodward.

Application Serial No. 478,922, filed December 30, 1954,

r in the names of Elkan R. Blout, Marilyn R. Cohler,

Milton Green, Myron S. Simon and Robert B. Woodward.

Application Serial No. 612,045, filed September '25, 1956, in the names of Elkan R. Blout, Milton Green and Howard 6.. Rogers.

Application Serial No. 612,052, filed September 25, 1956, in the names of Milton Green and Howard G. Rogers.

Application Serial No. 612,053, filed September 25, 1956,

. in the name of Myron S. Simon.

Application Serial No. 612,054, filed September 25, 1956, in the names of Helen P. Husek and Myron S. Simon.

Application Serial No. 612,055, filed September 25, 1956,

. in the "name of Helen P.-Husek.

Application Serial No. 755,804, filed August 18,1958, in the namesof Elkan R. Blout, Saul G. Cohen, Milton Green, and Myron S. Simon.

' In color difiusion transfer processes employing dye developers the dye developer, 'as mentioned previously for color-providing substances in general, is preferably placed in a separate alkali-permeable layer behind the photosensitive layer. Uponprocessing, the alkaline aqueous processing solution permeates to the separate alkalipermeable layer'and solubilizes the dye developer therebibed-on a superposed image-receiving element to create thereon the positive dye image. In such processes the immobilization of the dye developers in the exposed areas is apparently due,'at least, in part, to a change in the solubility characteristics of the dye developer upon oxidation, -It may also be due in part to a tanning .eflect on the emulsion by the oxidized developer. 7

FIG. 1 of the accompanying drawing illustrates one embodiment of a photosensitive element for use in 'color diffusion transfer processes wherein a p-acetamidobenzene sulfonate of a partially acetalized o-sodium sulfobenzal of polyvinyl alcohol is used as the material for a separate' alkali-permeable layer. The photosensitive element shown therein comprises a support 10, a layer 12 of a pacetamidobenzene sulfonate of'a partially acetalized sodium sulfobenzal of polyvinyl alcohol containing a color-providing substance and a photosensitive layer 14. i In preparing photosensitive elements of the type men- 'tioned above and in preparing other photosensitive elements within the scope of this invention, ,the polymeric layers may be'conveniently applied from coating solutions containing the desired polymer; The preferred coating solutions comprise 2 to of polymer; however, this amount-may be varied to suit particular needs. The

coating and drying operations may be carried out according to procedures well known to the art. The colorproviding substances which are to be disposed in the separate alkali-permeable layer may be incorporated into the coating solution and applied therewith, or they may be imbibed onto the layer after its application. When the color-providing substances are incorporated into the coating solutions, they may be dispersed or solubilized therein, depending upon the color-providing substance itself, the solvent used and the state desired for the diifusion transfer processes. As examples of suitable solvents which can be used in preparing'the coating solutions, mention may be made of methanol, 95% ethanol, and methanol-tetrahydrofuran mixtures. When the coating solution is applied directly to a support such, for example, as baryta, cellulose acetate, etc., said support may be first subcoated to further enhance the adhesion.

The polymers of this invention are also suitable as materials for alkali-permeable layers in integral multilayer photosensitive elements for use in multicolor diffusion transfer processes. As an example of such photosensitive elements, mention may be made of the photosensitive elements disclosed and claimed in the copending US. application of Edwin H. Land and Howard vG. Rogers, Sen'alNo. 565,135, filed February 13, 1956, wherein at least two selectively sensitized photosensitive strata are superposed on a single support and are processed, simultaneously and without separation, with a single common image-receiving element. A suitablearrangement of this type comprises a support carrying a red-sensitive silver halide emulsion stratum, a greensensitive silver halideemulsion stratum, and a blue-sensitive silver halide emulsion stratum, said emulsions having associated therewith, respectively, a cyan dye developer,

a magenta dye developer and a yellow dye developer. In one of the preferred embodiments of photosensitive elements of this type, the dye developers are disposed in separate alkali-permeable layers behind the photosensitive silver halide emulsion stratum with which they are associated. As in monochromatic photosensitive elements, the polymers of this invention, when used as materials for the alkali-permeable layers, provide superior wet and dry adhesion, as compared with cellulose acetate hydrogen phthalate, and also readily release the color-providing substances. When the polymers of this invention are used in such multicolor film units, at least one and usually all the color-providing substances are disposed in layers comprising the polymers of this invention. However, it should be understood that in certain instances it may be desirable for reasons such, for example, as permeation rates, transfer rates, etc., to dispose some of the colorproviding substances in the silver halide emulsions or in alkali-permeable layers of materials other than those disclosed herein.

A multilayer photosensitive element of the type mentioned above is illustrated in FIG. 2 of the accompanying drawing. A support 20 carries a layer 22 of a pacetamidobenzene sulfonate of a'partial o-sodium sulfobenzal of polyvinyl alcohol containing a cyan dye developer; a layer 24 of a red-sensitive silver halide emulsion; an interlayer 26, e.g., polyvinyl alcohol, gelatin, etc.; a layer 28 of a p-acetamidobenzene sulfonate of a partial o-sodium 'sulfobenzal. of polyvinyl alcohol containing a magenta dye developer; a layer 30 of a green-sensitive silver halide emulsion; an interlayer 32; a layer 34 of a p-acetamidobenzene sulfonate of a partial o-sodium sulfobenzal of polyvinyl alcohol containing a yellow dye developer; and an outermost layer 36 of a blue-sensitive silver halide emulsion. In certain instances, for example, when the yellow dye developer is not present in a state capable of functioning as a filter, a yellow filter-is placed in interlayer. 32. g 1 7 Although the mixed sulfo ester-acetal polymer layers in the photosensitive element of FIG. 2 are shown principally adhered to gelatin or polyvinyl alcohol layers, it

should be noted that the polymers of this invention show good adhesion to hydrophilic, alkali-permeable film-forming materials in general. As a result of this, wide discretion may be exercised in selecting film-forming materials as carriers for the silver halide emulsion, interlayers, and other layers which may be adjacent to the copolymer layers. For example, one may replace gelatin, which is the carrier usually used in the silver halide emulsion layer, in whole or in part, with gelatin substitutes such, for example, as cellulose ethers, polyvinyl alcohols, partially hydrolyzed organic esters of polyvinyl alcohols, acetals of polyvinyl alcohols, etc. Similar discretion may be exercised in selecting the film-forming materials for the interlayers and other layers. In certain instances, if desired, the polymers of this invention may be used as the carrier in the iuterlayers and other layers which may be present.

' Although the polymers of this invention provide good adhesion in and by themselves, in certain instances their adhesion to adjacent layers maybe enhanced by incorporating a small amount of said polymers into the layers to which they are to be adhered. The amount of polymer, so incorporated, may be varied to suit particular needs; generally, however, an amount comprising about by weight, of the adjacentcarrier material will provide the increased adhesion.

Both the monochromatic and multicolor photosensitive elements within the scope of this invention may be used in roll films which contain a plurality of photosensitive frames. The photosensitive elements of this invention are especially useful in composite roll films intended for use in a Polaroid Land Camera, sold by Polaroid Corporation, Cambridge 39, Massachusetts, or a similar camera structure such, for example, as the camera forming the subject matter of US. Patent No. 2,435,717, issued to Edwin H. Land on February 10, 1948. In general, such composite roll films comprise -a photosensitive roll, a roll of image-receiving material and a plurality of pods containing an aqueous alkaline processing solution. The rolls and pods are so associated with each other that, upon processing, the photosensitive element may be superposed on the image-receiving element and the pods may be ruptured to spread the aqueous alkaline processing solution between the superposed elements. The nature and construction of the pods used in such units are well known to the art. See, for example, U.S. Patents Nos. 2,543,181 and 2,634,886, issued to Edwin H. Land.

The polymers for use in preparing the photosensitive elements of this invention may be prepared by partially acetalizing polyvinyl alcohol with an ortho-, metaor para-benzaldehyde sulfonic acid and then reacting the resulting partial acetai with an ortho-, metaor para-acylamidobenzene sulfonyl chloride. Suitable polyvinyl alcohols, for use in the preparation, may be selected from the low, medium and high viscosity, partially and completely hydrolyzed polymers which are commercially available. As examples of such polymers, mention may be made of Elvanol 70-05 (low viscosity, completely hydrolyzed), Elvanol 31-31 (medium viscosity, about 76- 79% hydrolyzed), trade names of E. I. du Pont de Nemours & Co., Wilmington, Delaware) and Gelvatol 2-75 (trade name of Shawinigan Products Corp, New York, N.Y., for high viscosity, completely hydrolyzed polyvinylalcohol). The preferred acylamidobenzene sulfonyl chlorides, for use in the preparation, are those in which the acyl group comprises less than four carbon atoms, e.g., acetamidobenzene sulfonyl chloride and propionylamidobenzene suifonyl chloride. In preparing the polymers of this invention, the degree to which the hydroxyl groups are substituted by benzal or ester groups and the ratio of benzal substituted hydroxyl groups to sulfo esterified hydroxy groups can usually be varied to suit particular needs; however, the polymers which have been found to be particularly useful are those in which the hydroxyl groups are substantially fully substituted and in which said ratio is about 1.4 to 1. Although it is contemplated that thepolymers may be used as the free acid or as a salt, they are preferably employed as a salt because of their greater stability in such form. The preferred salts are those which are derived from bases which are capable of forming water-soluble salts, e.g., alkali metals, ammonia, amines, etc. When it is desired to have increased water resistance, hydrophobic amine salts of the polymers may be employed.

The following nonlimiting example illustrates the preparation of polymers within the scope of this invention:

Example 1 44 gms. of polyvinyl alcohol 70-05were placed in 400 m1. of glacial acetic acid'and gms. of o-benzaldehyde sulf-onie' acid (sodium salt) and 2 gms. of p-toluene sulfonic acid were added. The reaction was stirred and heated at 60 C. under nitrogen, for eighteen hours. The product was isolated by precipitation into acetone, purified by reprecipitation from methanol into acetone and dried, undervacuum, at 40 C. A sulphur analysis on the product indicated 41.6% of the hydroxyl groups remained unsubstituted.

10 gms. of the partial o-sodium sulfobenzal of polyvinyl alcohol 70-05, prepared as above, were dispersed in 75 gms. of dry pyridine. 14.61 gms. of p-acetamidobeuzene sulfonyl chloride were added 'and the mixture was stirred and heated at 40 C. The polymer was isolated by precipitation into acetone, purified by reprecipitation from water into acetone and dried, under vacuum at 45 C.

The following nonlimiting examples illustrate the preparation and use of photosensitive elements within the scope of this invention.

Example 2 A methanol-tetrahydrofuran coating solution (1 to l, by volume) comprising 2% of the polymer, as prepared in Example 1, and 3% of 1-phenyl-3-N-n-hexyl-carboxamido 4 [p-(2',5-dihydroxyphenethyl)-phenylazo]-5- pyrazolone (prepared by the processes disclosed in the previously mentioned copending US. application, Serial No. 612,045) was coated on a gelatin-subcoated cellulose acetate support. When the coating solution had dried, a silver halide emulsion layer was applied. 7

The above photosensitive element was exposed and then processed by spreading an aqueous processing solution comprising:

Percent Sodium carboxymethyl cellulose 5.0 Sodium hydroxide 2.0 1-phenyl-3-pyrazolidone 0.6

G-nitrobenzimidazole 0.12 2,5 -biseethyleneiminohydroquinone 0.4

between said photosensitive element and an image-receiving element as said elements were brought into superposed relationship. The image-receiving element comprised a cellulose acetate coated baryta paper which had been coated with an ethanol solution containing 4% of Nylon Type F 8 (trade name of El. du Pont de Nemours & Co., Wilmington, Delaware, for N-methoxymethyl polyhexamethylene adipamide). After an imbibition period of approximately one minute, the image-receiving element was separated and contained a dense yellow positive dye image of the photographed subject. No signs of wet delamination were observed. v

In the above example, the dry adhesion of the polymer layer was tested by adhering a strip of an adhesive film to the photosensitive element, stripping it from the element and observing for delamination. The photosensitive element, prepared in the above example, was superior to similar photosensitive elements prepared with cellulose acetate hydrogen phthalate as the dye carrier. The dry adhesion was further tested by bending the photosensitive phthalate as the carrier, without showing signs of delamination.

As mentioned previously the polymers of this invention may be used in integral multilayer photosensitive elements such as those disclosed in copending application No. 748,421. As examples of suitable coating solutions which may be used to apply the cyan, magenta and yellow dye developer layers in such elements mention may be made of:

(l) A tetrahydrofuran-methanol solution (1 to 1, by volume) comprising 5.5 %*of 1,4-bis-[B-(2',5'-dihydroxyphenyl)-isopropylamino]-anthaquinone (a cyan dye developer prepared in a manner similar to that disclosed in the previously mentioned copending application No. 478,922) and 2% of the polymer as prepared in Example 1. a

(2) A tetrahydrofuran-methanol solution (1 to 1, by volume) comprising 3.5% of 2-[p-(2',5'-dihydroxyphenethyle)-phenylazo]-4-n-propoxy-1-naphthol (a magenta dye developer prepared in a manner similar to that disclosed in the previously mentioned copending application No. 612,045) and 2% of the polymer, as prepared in Example 1.

(3) A tetrahydrofuran-methanol solution (1 to 1, by volume) comprising 3% of 1-phenyl-3-N-n-hexyl-carboxamido-4-[p-(2',5'-dihydroxyphenethyl) phenyla'zo] pyrazalone, (a yellow dye developer prepared in a manner similar to that disclosed in the previously mentioned copending application No. 612,045) and 2% of the polymer as prepared in Example 1.

The polymers of this invention are further suitable for use in screen type photosensitive elements such as disclosed in the aforementioned application of Howard G. Rogers, Serial No. 748,421, and also the copending application of Edwin H. Land, Serial No. 448,441, filed August 9, 1954, wherein at least two selectively sensitized silver halide emulsions are arranged in the form of a screen and the color-providing substances, as in multilayer photosensitive elements, are preferably placed in a separate alkali-permeable layer in back of the photosensitive emulsion with which they are associated.

In certain instances, minor irregular patterns, e.g., slight waviness, may be observed in the monochrome and multicolor transfer images produced from photosensitive elements wherein the color providing substances are disposed in hydrophilic layers. Such patterns, which detract only slightly from the good overall photographic quality of the image, appear to occur most frequently when aqueous coating solutions are usedto apply the layers which are to be directly over the layers containing the color-providing substances. Although the cause of such patterns is not known for certain, it is believed that in the coating operation the water of the coating solution permeates the hydrophilic layers and causes slight swellings and distortions which are transmitted to the transfer image. It has been discovered that such minor irregular patterns may be substantially eliminated by incorporating a small amount of a hydrophobic polymer into the hydrophilic layers. As examples of hydrophobic polymers which have been found to be especially useful, mention may be made of cellulose acetate and cellulose nitrate. The amount of hydrophobic polymers added may be varied to suit particular needs. Usually an amount equal to about 25% .of the hydrophilic polymer will produce the desired results.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it isintended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and notina sense.

What is claimed is:

1. A photosensitive element for difiusion transfer color processes, said element comprising a support, a polymeric layer having a color-providing substance selected from the group consisting of dyes and dye intermediates dis- -posed therein and a silver halide emulsion layer, said polymeric layer comprising a. polymer prepared by acetalizing a portion of the hydroxy groups of polyvinyl alcohol with a compound selected from the group consisting of ortho, metaand para-benzaldehyde sulfonic acids and then esterifying the resulting partial acetal with a compound selected from the group consisting of ortho-,

metaand para-acylamidobenzene sulfonyl chlorides, the

acyl group of said chlorides comprising less than 4 carbon atoms.

2. A photosensitive element as defined in claim 1 wherein said color-providing substance is a dye developer.

3. A photosensitive element as defined in claim 1 wherein said polymeric layer is between said support and said silver halide emulsion layer.

4. A photosensitive element as defined in claim 1 wherein the hydroxyl groups of said polymer are substantially fully substituted.

5. A photosensitive element as defined in claim 1 wherein the ratio of benzal substituted hydroxyl groups to sulfo esterified hydroxy groups in said polymer is about 1.4 to 1.

6. A photosensitive element as defined in claim 1 wherein said polymeric layer comprises a salt of said polymer.

7. A photosensitive element as defined in claim 6 wherein said salt is an alkali metal salt.

8. A photosensitive element for color difiusion transfer processes, said element comprising a plurality of photosensitive silver halide emulsions, each of said emulsions being selectively sensitized to different portions of the spectrum, a dye developer associated with each of said emulsions, said dye developer being a compound which contains within the same molecule a chromophoric system of a dye and also a silver halide developing function, atleast one of said dye developers being disposed in a polymeric layer contiguous with the emulsion with which it is associated, said polymeric layer comprising a polymer prepared by acetalizing a portion of the hydroxy groups of polyvinyl alcohol with a compound selected from the group consisting of ortho-, metaand para-benzaldehyde sulfonic acids and then esterifying the resulting partial acetal with a compound selected from the group consisting of ortho-, metaand para-acylamidobenzene sulfonyl chlorides, the acyl group of said chlorides comprising less than 4 carbon atoms.

9. A photosensitive element as defined in claim 8 wherein the hydroxyl groups of said polymer are substantially fully substituted.

10. A photosensitive element as defined in claim 8 wherein the ratio of benzal substituted hydroxyl groups to sulfo esterified hydroxyl groups in said polymer is about 1.4 to 1.

11. A photosensitive element as defined in claim 8 wherein said polymeric layer comprises a salt of said polymer.

12. A photosensitive element as defined in claim 11 wherein said salt is an alkali .metal salt.

13. In a process of forming a photographic image in color wherein the latent image contained in an exposed silver halide emulsion layer of a photosensitive element is developed to provide an imagewise distribution of C0101? providing substances selected from the group consisting of dyes and dye intermediates in said emulsion and said imagewise distribution of color-providing substances is transferred by an aqueous alkaline processing solution to a superposed image-receiving layer to impart to said image-receiving layer a color image, the improvement comprising having the color-providing substance in a polymeric layer behind the silver halide emulsion layer and, during processing, permeating said photosensitive element with said aqueous alkaline processing solution and solubilizing said color-providing substance from said polymeric layer, said polymeric layer comprising a polymer prepared by acetalizing a portion of the hydroxy groups of polyvinyl alcohol with a compound selected from the group consisting of ortho-, metaand parabenzaldehyde sulfonic acids and then esteri-fying the resulting partial acetal with a compound selected from the group consisting of ortho-, metaand para-acylamidobenzene sulfonyl chlorides, the acyl group of said chlorides comprising less than 4 carbon atoms.

14. A process as defined in claim 13 wherein the hydroxy-l groups of said polymer are substantially fully su stituted.

15. A process as defined in claim 13 wherein the ratio of benzal substituted hydroxyl groups to sulfo esterified hydroxyl groups in said polymer is about 1. 4 to 1.

16. A process as defined in claim 13 wherein said polymeric layer comprises a salt of said polymer.

17. A process as defined in claim 16 wherein said salt is an alkali metal salt. I

18. In a process of forming transparent images in color which comprises exposing a photosensitive emulsion containing a silver halide emulsion layer and a polymeric layer, said polymeric layer containing a dye developer, said dye developer being a compound which contains within the same molecule a chromoph'oric system of a dye and also a silver halide developing function, permeating said photosensitive element with an aqueous alkaline processing solution and solubilizing at least a portion of said d-ye developer from said polymeric layer, developing the latent image in the exposed emulsion in the presence of said dye developer whereby said dye developer is immobilized in the exposed areas but is mobile in unexposed areas, thereby providing an imagewise distribution of mobile dye developer, and transferring at least a portion of said mobile dye developer to a superposed image-receiving layer to form a positive image, the improvement comprising having the dye developer in a polymeric layer comprising a polymer prepared by acetalizing a portion of the hydroxy groups of polyvinyl alcohol with a compound selected from the group consisting of ortho-, metaand para-benzaldehyde sulfonic acids and then esterifying the resulting partial acetal with a compound selected from the group consisting of ortho-, metaand para-acylamidobenzene sulfonyl chlorides, the acyl group of said chlorides comprising less than 4 carbon atoms.

19. A process as defined in claim 18 wherein the hydroxyl groups of said polymer are substantially fully substituted.

20. A process as defined in claim 18 wherein the ratio of benzal substituted hydroxyl groups to sulfo esterified hydroxyl groups in said polymer is about 1.4 to l.

21. A process as defined in claim 18 wherein said polymeric layer comprises a salt of said polymer.

22. A process as defined in claim 21 wherein said salt is an alkali metal salt.

References Cited in the file of this patent UNITED STATES PATENTS 2,546,400 Murray Mar. 27, 1951 2,774,668 Rogers Dec. 18, 1956 2,892,710 Cohler et a1. June 30, 1959 FOREIGN PATENTS 484,306 Canada June 24, 1952

Claims (1)

1. A PHOSTOSENSITIVE ELEMENT FOR DIFFUSION TRANSFER COLOR PROCESSES, SAID ELEMENT COMPRISING A SUPPORT, A POLYMERIC LAYER HAVING A COLOR-PROVIDING SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF FYES AND DYE INTERMEDIATES DISPOSED THEREIN AND A SILVER HALIDE EMULSION LAYER, SAID POLYMERIC LAYER COMPRISING A POLYMER PREPARED BY ACETALIZING A PORTION OF THE HYDROXY GROUPS OF POLYVINYL ALCOHOL WITH A COMPOUND SELECTED FROM THE GROUP CONSISTING OF ORTHO-, META- AND PARA-BENZEALDEHYDE SULFONIC ACIDS AND THE ESTERIFYING THE RESULTING PARTIAL ACETAL WITH A COMPOUND SELECTED FROM THE GROUP CONSISTING OF ORTHOMETA-AND PARA-ACYLAMIDOBENZENE SULFONYL CHLORIDES THE ACYL GROUP OF SAID CHLORIDES COMPRISING LESS THAN 4 CARBON ATOMS.

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