EP0127431A2

EP0127431A2 - Hydrophilic layers adjacent a stripping layer for diffusion transfer assemblages

Info

Publication number: EP0127431A2
Application number: EP84303481A
Authority: EP
Inventors: John Francis Bishop; Thomas Otto Braun
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1983-05-23
Filing date: 1984-05-23
Publication date: 1984-12-05
Also published as: JPS633300B2; JPS59220727A; EP0127431B1; DE3474220D1; CA1213458A; EP0127431A3

Abstract

Photographic assemblages are described wherein a stripping layer is employed to enable an image-receiving layer to be separated from the rest of the assemblage after processing. Each side of the stripping layer has a hydrophilic layer immediately adjacent thereto, only one of which layers contains particulate material substantially insensitive to light and in a volume percentage of 5 to 75 percent of the hydrophilic material-particulate material mixture, so that upon separation, substantially all of the stripping layer will remain with the portion of the assemblage having the hydrophilic layer containing the particulate material.

Transparencies or prints which are less bulky can thereby be obtained from integral assemblages.

Description

This invention relates to photography, and more particularly to black-and-white and color diffusion transfer photography wherein a stripping layer with adjacent hydrophilic layers, one of which contains particulate material in a certain amount, is employed to enable an image-receiving layer to be cleanly separated from the rest of the assemblage after processing. In a preferred embodiment, the separated image-receiving layer has substantially none of the stripping layer adhered thereto.
Various formats for color, integral transfer elements are described in the prior art, such as U.S. Patents 3,415,644; 3,415,645; 3,415,646; 3,647,437; 3,635,707; 3,756,815, and Canadian Patents 928,559 and 674,082. In these formats, the image-receiving layer containing the photographic image for viewing remains permanently attached and integral with the image generating and ancillary layers present in the structure when a transparent support is employed on the viewing side of the assemblage. The image is formed by dyes, produced in the image generating units, diffusing through the layers of the structure to the dye image-receiving layer. After exposure of the assemblage, an alkaline processing composition permeates the various layers to initiate development of the exposed photosensitive silver halide emulsion layers. The emulsion layers are developed in proportion to the extent of the respective exposures, and the image dyes which are formed or released in the respective image generating layers begin to diffuse throughout the structure. At least a portion of the imagewise distribution of diffusible dyes diffuses to the dye image-receiving layer to form an image of the original subject. The user does not have to time this process.
A problem with the integral assemblages described above is that the silver halide and other imaging layers, the spent pod which originally contained processing fluid, and the trap which retains excess processing fluid remain with the print after processing. The resulting prints are bulky and are somewhat difficult to stock or store in albums.
Peel-apart formats for color diffusion transfer assemblages have previously been described, for example, in U.S. Patents 2,983,606, 3,362,819 and 3,362,821. In these formats, the image-receiving element must be separated from the photosensitive element after a certain amount of time has elapsed, usually about one minute. This requires the customer to time the process which may be a disadvantage if a clock is not available. Also, the portion of the assemblage to be discarded is wet with caustic processing fluid, and care must be taken with its handling.
U.S. Patent 3,730,718 relates to diffusion transfer assemblages wherein a stripping layer is employed so that an image-receiving layer may be separated from a light-sensitive element during development. In the example in that patent, a stripping layer is employed between layers, both of which contain particulate material. However, assemblages wherein particulate material is present in layers on both sides of a stripping layer exhibit nonuniform fracture of the stripping layer upon separation, with the dis- advantages as described below.
U.S. Patent 4,359,518 also relates to diffusion transfer assemblages wherein a stripping sheet is employed in conjunction with a release layer to effect stripping a photosensitive layer from a film unit after processing. Particulate material such as silica particles are employed in a timing layer of the stripping sheet to prevent blocking and to function as an antistatic agent. In Example A of that patent, a release layer is employed between a silver halide emulsion layer and a "protective layer", the composition of which appears to be unknown. This patent, however, does not disclose the use of a hydrophilic layer located between the stripping layer and the silver halide emulsion layer and which contains particulate material as described herein.
A problem has developed with the use of stripping layers in assemblages such as described above. While it is highly desirable to have the stripping layer be removed in one uniform piece and remain with the separated portion that is to be discarded, in practice it has been found that the stripping layer itself fractures. This results in portions of the stripping layer randomly adhering to the two separated surfaces. A very blotchy appearance thus results on the back of the separated image-receiving layer which is undesirable in a commercial product. This blotchy appearance is particularly noticeable in D_min areas of a transparency format.
The object of the present invention is to provide a photographic assemblage comprising

a) a photosensitive element comprising a support having thereon at least one photosensitive silver halide emulsion layer;
b) an image-receiving layer; and
c) a stripping layer located between said silver halide emulsion layer and said image-receiving layer so that said image-receiving layer may be separated, after processing, from the portion of said assemblage containing said silver halide emulsion layer.

This object is achieved with a photographic assemblage as described above which is characterized in that each side of the stripping layer has a hydrophilic layer immediately adjacent thereto, other than a photosensitive silver halide emulsion layer or an image-receiving layer, and only one of the hydrophilic layers contains particulate material substantially insensitive to light and in a volume percentage of 5 to 75 percent of the hydrophilic material-particulate material mixture in that layer, so that upon separation, substantially all of the stripping layer will remain with the portion of the assemblage having the hydrophilic layer containing the particulate material.
In a preferred embodiment of the invention, the hydrophilic layer which contains the particulate material is located between the stripping layer and the silver halide emulsion layer so that upon separation, substantially all of the stripping layer will remain with the portion of the assemblage containing the silver halide emulsion layer.
In forming a black-and-white image, the exposed photosensitive element is developed. In the unexposed areas, a silver halide complexing agent dissolves the silver halide and transfers it to the image-receiving layer. Silver precipitating nuclei in the image-receiving layer then cause the transferred silver halide complex to be reduced to silver, thereby forming an image pattern corresponding to the original. Details of the process are well known to those skilled in the art as shown, for example, by U.S. Patents 3,220,835 and 3,820,999.
In a preferred embodiment of the invention, the silver halide emulsion layer has associated therewith a dye image-providing material.
Any material may be employed as the stripping layer in the invention provided it has the required properties. Such materials are disclosed, for example, in U.S. Patents 3,220,835, 3,730,718 and 3,820,999 and include gum arabic, sodium alginate, pectin, polyvinyl alcohol and hydroxyethyl cellulose. In a preferred embodiment of this invention, hydroxyethyl cellulose is employed.
The stripping layer materials employed in this invention can be employed in any amount which is effective for the intended purpose. Good results have been obtaiqed at a concentration of from 5 to 2000 mg/m² of element. The particular amount to be employed will vary, of course, depending on the particular stripping layer material employed and the particular diffusion transfer element selected.
The materials employed in the hydrophilic layers on each side of the stripping layer in this invention include any of the well known materials commonly used in the photographic art for such use. These materials include, for example, gelatin, polysaccharides, acrylamide polymers and other polymeric materials such as those disclosed in Research Disclosure, Vol. 176, December 1978, Item 17643, page 26. In a preferred embodiment of the invention, gelatin is employed. The coverage of the hydrophilic layer can be widely varied, as desired. Good results have been obtained at coverages ranging from 0.1 to 2.0 g/m² of element.
The particulate material employed in the hydrophilic layers of the invention described above can be any material provided it produces the desired results of tightly bonding that layer to the adjacent stripping layer. Such material should not be light-sensitive since it would interfere with the imaging chemistry in the light-sensitive portion of the photosensitive element. Good results have been obtained with carbon black, such as Cabot Regal 400^* carbon black, average particle diameter 0.07pm and CITGO (Columbia) Carbon Raven 410°, average particle diameter 0.07 pm; titanium dioxide, such as Gulf and Western Horsehead° Rutile, average particle diameter 0.25 pm; colloidal silica such as DuPont Ludox° AM, average particle diameter 0.012 pm; and poly(methyl methacrylate) beads, average particle diameter 0.5 um. In a preferred embodiment, carbon black is employed.
The particle size of the particulate material employed in the invention can vary widely, as evidenced by the range of particle sizes shown above. In general, the particle size will range from 0.01 um to 0.5 um. The amount of particulate material to be coated can also vary widely, as long as the volume percentage of particulate material in the hydrophilic material-particulate material mixture in that layer is from 5 to 75 percent. Where less than 5 percent, or more than 75 percent, of particulate material is employed the desirable improvements in layer separation will not be realized. This percentage is commonly referred to in the art as a PVC percentage (pigment volume content). A preferred range of PVC percentages for the invention is from 10 to 50 percent. The amount of particulate material to be coated in the hydrophilic layer is a function of its density.
Particulate material has been employed in photographic elements for a number of reasons. For example, in U.S. Patent 4,259,518, discussed above, it is disclosed in column 4 that silica particles in the outermost layer prevents blocking when the stripping layer is wound upon itself. Such materials are known in the art as "anti-blocking" agents. It would have been expected, therefore, that such material in a layer would decrease the adhesion of that layer to an adjacent layer. It was unexpectedly found in accordance with this invention, however, that just the opposite occurred. It was found that the hydrophilic layer adjacent the stripping layer which contains the particulate material has a stronger bond to the stripping layer than does the hydrophilic layer on the other side thereof. Since stripping occurs at the weakest interface bond, this enables the stripping layer to remain, after separation, with the portion of the assemblage to be discarded, usually the portion containing the silver halide emulsion layer or layers. Thus, the stripped image-receiving layer in that case will have a clean appearance on the reverse side thereof.
The employment of particulate material in one of the hydrophilic layers adjacent to the stripping layer in the assemblages described herein is the means whereby the bond between these two layers can be strengthened. This ensures that stripping will take place at the opposite side of the stripping layer. The hydrophilic layer on the opposite side of the stripping layer should be substantially free of particulate material since any appreciable amount of particulate material in that layer would tend undesirably to strengthen the bond between that layer and the stripping layer.
This invention can be used in diffusion transfer assemblages where a reflection print is obtained without the bulkiness of silver halide and other layers, the spent pod and trap. In other words, the assemblages of this invention combines the handling and storage characteristics of conventional photographs with the convenience and benefits of instant photography. Transparencies can also be obtained in the same manner. In addition, transparency elements can also be obtained in accordance with the invention by employing a transparent support and utilizing the retained image in the element along with the subsequent removal of residual image dye, silver halide and opacifying layers. In that embodiment, it would be desirable to have the stripping layer remain with the portion of the assemblage containing the dye image-receiving layer, since that portion is the one to be discarded. In that case, the particulate material would be located in the hydrophilic layer between the stripping layer and the dye image-receiving layer. Clean separation would then occur on the other side of the stripping layer where it is desired.
By removing the silver halide and dye image-providing material layers from the assemblage, there is also provided the option of recovery of these expensive materials from the discarded portion of the assemblage, if it is economically feasible to do so.
A process for producing a photographic image in color according to this invention comprises:

I) exposing a photosensitive element comprising a support having thereon at least one photosensitive silver halide emulsion layer having associated therewith a dye image-providing material;
II) treating the element with an alkaline processing composition in the presence of a silver halide developing agent to effect development of each exposed silver halide emulsion layer, whereby:
- (a). an imagewise distribution of the dye image-providing material is formed as a function of the development of the silver halide emulsion layer; and
- (b) at least a portion of the imagewise distribution of the dye image-providing material diffuses to a dye image-receiving layer; and
III) separating the dye image-receiving layer from the rest of the photosensitive element by means of a stripping layer and adjacent hydrophilic layers as described above, so that substantially all of said stripping layer will remain with the portion of the element having the hydrophilic layer containing the particulate material as described above.

The photographic element in the above- described process can be treated with an alkaline processing composition to effect or initiate development in any manner. A preferred method for applying processing composition is by use of a rupturable container or pod,which contains the composition.
In a preferred embodiment of the invention the photographic assemblage comprises:

a) a photosensitive element comprising a support having thereon at least one silver halide emulsion layer having associated therewith a dye image-providing material;
b) a transparent cover sheet located over the layer outermost from the support of the photosensitive element;
c) a dye image-receiving layer located either in the photosensitive element or on the transparent cover sheet; and
d) an alkaline processing composition and means containing same for discharge between the photosensitive element and the transparent cover sheet;
and wherein the assemblage contains a stripping layer and adjacent hydrophilic layers as described above.

In a preferred embodiment of the invention, the means containing the alkaline processing composition is a rupturable container or pod which is adapted to be positioned during processing of the assemblage so that a compressive force applied to the container by pressure-applying members, such as would be found in a camera designed for in-camera processing, will effect a discharge of the container's contents within the assemblage.
The dye image-providing material useful in this invention is either positive- or negative-working, and is either initially mobile or immobile in the photographic element during processing with an alkaline composition.
A format for integral negative-receiver photographic elements in which the present invention is useful is disclosed in Canadian Patent 928,559. In this embodiment, the support for the photographic element is transparent and is coated with the image-receiving layer, a substantially opaque, light- reflective layer, the stripping layer and adjacent hydrophilic layers described above, and the photosensitive layer or layers described above. A rupturable container, containing an alkaline processing composition including a developing agent and an opacifier, is positioned between the top layer and a transparent cover sheet which has thereon, in sequence, a neutralizing layer, and a timing layer. The film unit is placed in a camera, exposed through the transparent cover sheet and then passed through a pair of pressure-applying members in the camera as it is being removed therefrom. The pressure-applying members rupture the container and spread processing composition and opacifier over the negative portion of the film unit to render it light-insensitive. The processing composition develops each silver halide layer and dye images, formed as a result of development, diffuse to the image-receiving layer to provide a positive, right-reading image which is viewed through the transparent support on the opaque reflecting layer background.
Still other useful integral formats in which this invention can be employed are described in U.S. Patents 3,415,644; 3,415,645; 3,415,646; 3,647,437 and 3,635,707.
The assemblage of the present invention is used to produce positive images in single or multicolors. In a three-color system, each silver halide emulsion layer of the film assembly will have associated therewith a dye image-providing material which possesses a predominant spectral absorption within the region of the visible spectrum to which said silver halide emulsion is sensitive. The dye image-providing-material associated with each silver halide emulsion layer is contained either in the silver halide emulsion layer itself or in a layer contiguous to the silver halide emulsion layer.
A variety of silver halide developing agents are useful in this invention. Specific examples of developers or electron transfer agents (ETA's) useful in this invention include hydroquinone, catechol and 3-pyrazolidinone compounds. A combination of different ETA's, such as those disclosed in U.S. Patent 3,039,869, can also be employed.
Use of a neutralizing material in the described assemblages increases the stability of the transferred image. The neutralizing material will effect a reduction in the pH of the image layer from about 13 or 14 to at least 11 and preferably 5 to 8 within a short time after imbibition. Suitable materials and their functioning are disclosed on pages 22 and 23 of the July 1974 edition of Research Disclosure, and pages 35 through 37 of the July 1975 edition of Research Disclosure.--
A timing or inert spacer layer can be employed over the neutralizing layer which "times" or controls the pH reduction as a function of the rate at which alkali diffuses through the inert spacer layer. Examples of such timing layers and their functioning are disclosed in the Research Disclosure articles mentioned in the paragraph above concerning neutralizing layers.
The term "nondiffusing" used herein has the meaning commonly applied to the term in photography and denotes materials that for all practical purposes do not migrate or wander through organic colloid layers, such as gelatin, in the photographic elements of the invention in an alkaline medium and preferably when processed in a medium having a pH of 11 or greater. The same meaning is to be attached to the term "immobile". The term "diffusible" as applied to the materials of this invention has the converse meaning and denotes materials having the property of diffusing effectively through the colloid layers of the photographic elements in an alkaline medium. "Mobile" has the same meaning as "diffusible".
The term "associated therewith" as used herein is intended to mean that the materials can be in either the same or different layers, so long as the materials are accessible to one another.
The following examples are provided to further illustrate the invention.

Example 1

A) A control integral imaging-receiver (IIR) element was prepared by coating the following layers in the order recited on a transparent poly(ethylene terephthalate) film support. Quantities are parenthetically given in grams per square meter, unless otherwise stated.

(1) Image-receiving layer of poly(styrene-co-N-benzyl-N,N-dimethyl-N-vinylbenzylammonium chloride-co-divinylbenzene) (molar ratio 49/49/2) (1.1) and gelatin (1.2);
(2) Image-receiving layer of poly(styrene-co-l-vinylimidazole-co-3-benzyl-1-vinylimidazolium chloride) (50:40:10 mole ratio) (1.6) and gelatin (0.75);
(3) Reflecting layer of titanium dioxide (17) and gelatin (2.6);
(4) Opaque layer of carbon black (0.95) and gelatin (0.65);
(5) Gelatin interlayer (0.54);
(6) Stripping layer of Natrosol° GXR-250 hydroxyethyl cellulose (0.81);
(7) Gelatin interlayer (0.65);
(8) Cyan dye releaser B of U.S. Patent 4,356,250 (0.37) and gelatin (0.54); and
(9) Gelatin overcoat (0.43).

It should be noted that layers 8 and 9 represent the top and bottom layers of a complete IIR such as described in Example 1 of U.S. Patent 4,356,250. For purposes of this test, it was not necessary to have a complete light-sensitive element.
B) An IIR similar to A) was prepared except that layer 7 also contained poly(methylmethacrylate) beads (0.56), average particle diameter 0.5 µm, 47X PVC (pigment volume content).
C) An IIR similar to A) was prepared except that layer 7 also contained poly(methylmethacrylate) beads (0.18), average particle diameter 0.5 µm, PVC 22%.
D) An IIR similar to A) was prepared except that layer 7 also contained DuPont Ludox° AM colloidal silica (0.95), average particle diameter 0.012 pm, PVC 471.
E) An IIR similar to A) was prepared except that layer 7 also contained DuPont Ludox° AM colloidal silica (0.32), average particle diameter 0.012 pm, PVC 23%.
F) An IIR similar to A) was prepared except that layer 7 also contained Cabot Regal 400 carbon black (0.95), average particle diameter 0.07 µm, PVC 50%.
G) An IIR similar to A) was prepared except that layer 7 also contained Cabot Regal 400 carbon black (0.32), average particle diameter 0.07 pm, PVC 25%.
H) An IIR similar to A) was prepared except that layer 7 also contained Gulf and Western Horsehead Rutile titanium dioxide (1.8), average particle diameter 0.25 pm, PVC 48%.
I) An IIR similar to A) was prepared except that layer 7 also contained Gulf and Western Horsehead Rutile titanium dioxide (0.59), average particle diameter 0.25 pm, PVC 24%.
The above coatings were prepared with nearly constant PVC percentages of particulate material, thus the actual coated weights vary.
A "tape test" was run on the above IIR's. This test has a high correlation with actual stripping performances in actual photographic coatings. The test consists of firmly applying a short strip of 3M Scotch° 810 Magic Transparent Tape on the top of layer 9 of the IIR to be tested and then rapidly pulling on the tape.
IIR's B through I thus tested stripped at the point between layers 6 and 5, thus indicating the weakest bond in the element. In control IIR A, a random discontinuous stripping occurred.
A second tape test was run on the residual element on top of layer 6 to determine the next weakest bond. If layer 6 was not removed by this second test, then the bond between layers 7 and 6 was considered to be strong. If layer 6 was removed by the second tape test, then the bond was considered to be weak (but none-the-less stronger than the bond between layers 6 and 5).
The following results were obtained:
The above results indicate that in all instances, employing particulate material in a hydrophilic layer adjacent a stripping layer improves the adhesion between those two layers, thus causing stripping to occur on the opposite side of the stripping layer. In IIR elements B, D, F and H, a strong bond was obtained between layers 6 and 7 due to the higher concentration of particulate material employed.

Example 2

A) An IIR similar to that of A) in Example 1 was prepared except that after layer 7, the following layers were employed:

(8) Cyan redox dye-releaser layer,
(9) Gelatin interlayer,
(10) Red-sensitive silver halide emulsion layer,
(11) Gelatin interlayer,
(12) Magenta redox dye-releaser layer,
(13) Green-sensitive silver halide emulsion layer,
(14) Gelatin interlayer,
(15) Yellow redox dye-releaser layer,
(16) Blue-sensitive silver halide emulsion layer, and
(17) Gelatin overcoat layer.

Layers 8-17 are similar to those described in Example 1 of U.S. Patent 4,356,250 of Irani et al.
B) An IIR similar to A) was prepared except that layer 7 also contained DuPont Ludox° AM colloidal silica (0.11), average particle diameter 0.012 µm, PVC of 9.
C) An IIR similar to A) was prepared except that layer 7 also contained DuPont Ludox° AM colloidal silica (0.32), average particle diameter 0.012 pm, PVC of 23.
D) An IIR similar to A) was prepared except that layer 7 also contained DuPont Ludox° AM colloidal silica (0.65), average particle diameter 0.012 µm, PVC of 38.
E) An IIR similar to A) was prepared except that layer 7 also contained DuPont Ludox° AM colloidal silica (0.95), average particle diameter 0.012 µm, PVC of 48.
F) An IIR similar to A) was prepared except that layer 7 also contained CITGO (Columbia) Carbon Raven 410° carbon black (0.11), average particle diameter 0.07 µm, PVC of 10.
G) An IIR similar to A) was prepared except that layer 7 also contained CITGO (Columbia) Carbon Raven 410⁰ carbon black (0.32), average particle diameter 0.07 µm, PVC of 25.
H) An IIR similar to A) was prepared except that layer 7 also contained CITGO (Columbia) Carbon Raven 410° carbon black (0.65), average particle diameter 0.07 µm, PVC of 40.
I) An IIR similar to A) was prepared except that layer 7 also contained CITGO (Columbia) Carbon Raven 410° carbon black (0.95), average particle diameter 0.07 µm, PVC of 52.
A cover sheet and processing pod were also prepared similar to those in Example 1 of U.S. Patent 4,356,250, and assembled into film assemblages.
The above film assemblages were exposed to a graduated density color test object (to verify that the stripping layer and adjacent hydrophilic layer had no sensitimetric effect). The assemblages were then processed by spreading the contents of the processing pod between the cover sheet and IIR by using a pair of juxtaposed rollers. The film assemblages, as assembled, were then incubated for 1 week at room temperature, 3 weeks at room temperature, and 3 weeks at 32°C/15% RH. Each assemblage was then manually peeled apart to separate the receiver portion from the upper silver halide emulsion layers.
Ideally, separation should occur between layers 5 and 6 (designated as location 1). Sometimes the separation occurred between layers 6 and 7 (designated as location 2). This leaves objectionably visible irregular shaped areas of the stripping layer on the back of the peeled receiver. In other instances, separation occurred in various locations from layer 8 upward (designated as location 3). This is the least desirable point of separation as the emulsion layer(s) and dye releaser layer(s) are retained on the element with the image and may cause stain problems in addition to being visually objectionable.
The data below show the stripping behavior for the different particulate materials in layer 7, coated adjacent to stripping layer 6. The area percent separation is tabulated by locations 1/2/3. Ideal separation would thus be 100/0/0; 100 area percent separation between layers 5 and 6 for both wet (center) and dry (edge) areas. Very poor separation, such as 30/60/10, indicates that less than one-third of the area separated between layers 5 and 6, almost two-thirds of the stripping layer was retained on the back of the separated receiver, and significant portions of the emulsion layers were fractured.
Separation is initiated in the dry outer mask area of the assemblage and continues through the initially wet center image area. Thus, clean separation is desirable within both the dry and wet areas of the assemblage as well as at the interface. The following results were obtained:
The above results indicate that the addition of particulate material to layer 7 improved both wet and dry stripping. In most cases, improved separation between layers 5 and 6 was obtained as the quantity of silica or carbon black was increased. Very high levels should be avoided, however, as problems will arise with poor layer integrity (spontaneous separation) and brittleness.

Claims

1. A photographic assemblage comprising:

a) a photosensitive element comprising a support having thereon at least one photosensitive silver halide emulsion layer;

b) an image-receiving layer; and

c) a stripping layer located between said silver halide emulsion layer and said image-receiving layer so that said image-receiving layer may be separated, after processing, from the portion of said assemblage containing said silver halide emulsion layer, characterized in that each side of said stripping layer has a hydrophilic layer immediately adjacent thereto, other than a photosensitive silver halide emulsion layer or an image-receiving layer, and only one of'.said hydrophilic layers contains particulate material substantially insensitive to light and in a volume percentage of from 5 to 75 percent of the hydrophilic material-particulate material mixture in that layer, so that upon separation, substantially all of said stripping layer will remain with the portion of said assemblage having said hydrophilic layer containing said particulate material.

2. An assemblage according to claim 1 characterized in that said hydrophilic layer which contains particulate material is located between said stripping layer and said silver halide emulsion layer so that upon separation, substantially all of said stripping layer will remain with the portion of said assemblage containing the silver halide emulsion layer.

3. An assemblage according to claim 2 characterized in that there is also contained an alkaline processing composition and means containing same for discharge within said assemblage.

4. An assemblage according to claim 3 characterized in that said image-receiving layer contains silver precipitating nuclei.

5. An assemblage according to claim 3 characterized in that said silver halide emulsion layer has associated therewith a dye image-providing material.

6. An assemblage according to claim 5 characterized in that said stripping layer comprises hydroxyethyl cellulose.

7. An assemblage according to claim 5 characterized in that said particulate material comprises carbon black, titanium dioxide, silica or poly(methyl methacrylate) beads.

8. An assemblage according to claim 5 characterized in that each said hydrophilic layers - comprises gelatin.

9. An assemblage according to claim 8 characterized in that said particulate material is carbon black.

10. An assemblage according to claim 5 characterized in that said particulate material has an average particle diameter of from 0.01 pm to 0.5 pm and is present in a volume percentage of from 10 to 50 percent of said hydrophilic material-particulate material mixture in that layer.