Diffusion transfer films and processes are disclosed wherein the processing composition includes a light-reflecting pigment and an optical filter agent, and the image-receiving layer carries over it a layer containing a substantially non-diffusible agent adapted to decolorize optical filter agent immediately adjacent the interface between said processing composition and said decolorizing layer.

This invention is concerned with photography and, more particularly, with 
photographic processes which are conducted outside of the camera in which 
the film is exposed. 
U.S. Pat. No. 3,415,644 issued Dec. 10, 1958 to Edwin H. Land discloses 
photographic products and processes wherein a photosensitive element and 
an image-receiving element are maintained in fixed relationship prior to 
exposure, and this relationship is maintained as a laminate after 
processing and image formation. In these products and processes, the final 
image is viewed through a transparent (support) element against a 
reflection, i.e., white, background. Photoexposure is made through said 
transparent element and application of the processing composition provides 
a layer of light-reflecting material to provide a white background for 
viewing the final image through said transparent support. The 
light-reflecting material (referred to in said patent as an "opacifying 
agent") is preferably titanium dioxide, and it also performs an opacifying 
function, i.e., it is effective to mask the developed silver halide 
emulsions so that the transfer image may be viewed without interference 
therefrom, and it also helps to protect the photoexposed silver halide 
emulsions from post-exposure fogging by light passing through said 
transparent layer if the photoexposed film unit is removed from the camera 
before image-formation is completed. 
U.S. Pat. No. 3,647,437, issued Mar. 7, 1972 to Edwin H. Land, discloses 
photographic products which may be processed outside of the camera in 
which the film is exposed, fogging of the film by ambient light being 
prevented by provision of one or more opacifying dyes, sometimes referred 
to as light-absorbing optical filter agents, appropriately positioned in 
the film unit after photoexposure. In a particularly useful embodiment of 
that invention, the film unit is a film unit of the type described in the 
aforementioned U.S. Pat. No. 3,415,644 and comprises first and second 
sheet-like elements, the first sheet-like element comprising an opaque 
base carrying a silver halide emulsion, and the second sheet-like element 
comprising a transparent support carrying an image layer, i.e., a layer 
adapted to receive an imagewise distribution of an image-forming material 
initially present in said first sheet-like element. After photoexposure a 
processing composition, adapted to develop the exposed silver halide 
emulsion and to form the desired image in said image layer, is distributed 
in a thin layer between said sheet-like elements. The processing 
composition contains a light-reflecting pigment, such as titanium dioxide, 
and at least one light-absorbing optical filter agent, such as a 
pH-sensitive phthalein dye which is colored at the initial pH of said 
processing composition. As disclosed in said U.S. Pat. No. 3,647,437, the 
concentrations of said light-reflecting pigment and said optical filter 
agent(s) are such that the layer of processing composition is sufficiently 
opaque to light actinic to the silver halide emulsion that the film unit 
may be ejected from the camera immediately after the processing 
composition is distributed, notwithstanding the fact that the second 
sheet-like element will transmit light incident on the surface thereof. 
This opacification system is quite effective and is employed in Polaroid 
Land SX-70 film. The light-absorbing capacity of the optical filter agent 
is discharged after this ability is no longer needed, so that the optical 
filter agent need not be removed from the film unit. Where the optical 
filter agent is a pH-sensitive dye, such as a phthalein indicator dye, it 
may be discharged or decolorized by reducing the pH after a predetermined 
time, e.g., by making available an acid-reacting material such as a 
polymeric acid. 
In the preferred embodiments of the opacification system described in U.S. 
Pat. No. 3,647,437 the concentrations of the light-reflecting pigment and 
light-absorbing optical filter agent in the layer of processing 
composition will be such that that layer will have a transmission density 
of at least about 6 but a reflection density not greater than about 1. The 
presence of a long chain substituent, e.g., a long chain alkoxy group, on 
the optical filter agent is useful in reducing its diffusibility so that 
diffusion to the image-receiving layer is minimized. 
A reflection density of about 1 will be recognized as very small compared 
with a transmission density of 6 or more for the same layer. In practice 
it has been possible to use a concentration of optical filter agents and 
titanium dioxide such that the reflection density of the processing 
composition layer, as measured about 30 seconds after distribution, is 
much lower than 1, e.g., about 0.5 to 0.6. While transferring dye and the 
emerging dye image may be seen at opacification system reflection 
densities of about 0.5, the presence of such temporary coloration of the 
highlight or white areas of the image, and the temporary distortion of the 
colors of the already transferring image dyes, is aesthetically 
undesirable. 
As noted above, where the optical filter agent is a pH-sensitive dye, it is 
"discharged", i.e., rendered substantially colorless, by a reduction of 
the pH of the strata containing the optical filter agent. These strata 
include the light-reflecting pigment layer, provided by the processing 
composition, as well as the image-receiving layer and any other layers 
between the light-reflecting pigment layer and the transparent support 
through which the final image is viewed. This pH reduction is effected, to 
a pH level below the pKa of the optical filter agent, after a 
predetermined time. This delay is necessary in order that silver halide 
development be substantially completed before incident light is 
transmitted to the developing silver halide emulsions. Since the image 
dyes are preferably soluble and diffusible at the initial pH of the 
process but substantially nondiffusible at a lower pH, reduction of the pH 
to the appropriate lower pH after a predetermined period serves the very 
important function of controlling unwanted continued transfer of image 
dyes after the desired dye image has been formed. 
It will be recognized that these desired results of pH reduction are only 
partly compatible, for early pH reduction to provide a white background 
early in the process could prematurely stop transfer of image dyes, 
resulting in a pale, i.e., low density, image which may also have an 
unbalanced color balance. 
The copending application of Edwin H. Land, Leon D. Cerankowski and Neil 
Mattucci, Ser. No. 33,001, filed Apr. 24, 1979 (now abandoned and replaced 
by a continuation-in-part thereof, Ser. No. 143,293 filed Apr. 24, 1980), 
discloses and claims diffusion transfer products and processes of the 
foregoing type where the background appears substantially white to the 
viewer, substantially immediately after the processing composition is 
applied while retaining opacification. As disclosed in said application, 
it has been found that it is possible to significantly reduce the 
reflection density provided by the layer of processing composition 
containing the light-reflecting pigment and the optical filter agent 
without significantly reducing the transmission density thereof. This 
highly desirable improvement is obtained by decolorizing, substantially 
immediately after application of the processing composition, the optical 
filter agent immediately adjacent the interface between the processing 
composition and the layer of the second sheet-like element in contact with 
the processing composition. It is only necessary to decolorize a very 
small fraction of the applied optical filter agent in order to effectively 
render the interface substantially "white" when viewed by reflection. 
Since the reflection density is the result of light being absorbed twice 
by a given quantity of dye--once when the light enters and a second time 
when it is reflected back--it will be seen that decolorization of even a 
few molecules of dye adjacent the interface provides an effect which is so 
amplified by the optics of reflection that one can substantially lower the 
reflection density and increase the apparent whiteness of the layer of the 
processing composition providing the background against which the image is 
viewed without reducing the transmission density of the "white" layer to 
any significant extent. 
The "decolorizing" layer is provided between the image-receiving layer and 
the layer of processing composition. This decolorizing layer comprises a 
substantially nondiffusible agent adapted to decolorize the small 
concentration of optical filter agent which is present immediately 
adjacent the interface between the processing composition and the 
decolorizing layer. This decolorizing is essentially limited to the 
optical filter agent which is present immediately adjacent the interface 
between the decolorizing layer and the processing composition. Even though 
the decolorizing layer is relatively thin it inhibits diffusion of optical 
filter agent into the image-receiving layer where it may react with the 
mordant to form a "new species" whose color is discharged only at a lower 
pH; e.g., the new species exhibits a much lower pKa and remains colored 
until the pH is reduced to a much lower level than otherwise would be 
required for decolorization. The remaining optical filter agent is 
discharged or decolorized by a subsequent pH reduction. 
In the preferred embodiments, the decolorizing agent is a polyoxyalkylene 
polymer and the optical filter agent is a pH-sensitive phthalein dye. Such 
polyoxyalkylene polymers tend to be "soft" or waxy materials, tend to rub 
off or to "block" when the sheet is rolled up and be pulled off when the 
sheet is unrolled. 
The present invention provides decolorizing layers containing polyether, 
i.e., polyoxyalkylene polymers which layers are "hard" and exhibit good 
adhesion to the image-receiving layer of the image-receiving element. In 
accordance with the present invention, the decolorizing layer comprises a 
polyoxyalkylene polymer hydrogen-bonded to another polymer to provide a 
"hard" decolorizing layer. 
As indicated above, this invention is primarily directed to photographic 
processes wherein the desired image is obtained by processing an exposed 
photosensitive silver halide material, with a processing composition 
distributed between two sheet-like elements, one of said elements 
including said photosensitive material. The processing composition is so 
applied and confined within and between the two sheet-like elements as not 
to contact or wet outer surfaces of the superposed elements, thus 
providing a film unit or film packet whose external surfaces are dry. The 
processing composition is viscous and preferably is distributed from a 
single-use rupturable container; such pressure rupturable processing 
containers are frequently referred to as "pods". The final image may be 
black-and-white, monochrome or multicolor and either negative or positive 
with respect to the photographed subject. The present invention is 
especially, if not uniquely, adapted for facilitating processing outside 
of a camera film units which are maintained as an integral laminate after 
processing, the desired image being viewed through one face of said 
laminate. 
In diffusion transfer embodiments of this invention the diffusible 
image-providing substance may be a complete dye or a dye intermediate, 
e.g., a color coupler. The preferred embodiments of this invention use a 
dye developer, that is, a compound which is both a silver halide 
developing agent and a dye disclosed in U.S. Pat. No. 2,983,606, issued 
May 9, 1961 to Howard G. Rogers. As is now well known, the dye developer 
is immobilized or precipitated in developed areas as a consequence of the 
development of the latent image. In unexposed and partially exposed areas 
of the emulsion, the dye developer is unreacted and diffusible and thus 
provides an imagewise distribution of unoxidized dye developer, diffusible 
in the processing composition, as a function of the point-to-point degree 
of exposure of the silver halide emulsion. At least part of this imagewise 
distribution of unoxidized dye developer is transferred, by imbibition, to 
a superposed image-receiving layer to provide a reversed or positive color 
image of the developed image. The image-receiving layer preferably 
contains a mordant for transferred unoxidized dye developer. As disclosed 
in the aforementioned U.S. Pat. Nos. 2,983,606 and 3,415,644, the 
image-receiving layer need not be separated from its superposed contact 
with the photosensitive element, subsequent to transfer image formation, 
if the support for the image-receiving layer, as well as any other layers 
intermediate said support and image-receiving layer, is transparent and a 
processing composition containing a substance, e.g., a white pigment, 
effective to mask the developed silver halide emulsion or emulsions is 
applied between the image-receiving layer and said silver halide emulsion 
or emulsions. 
Dye developers, as noted above, are compounds which 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 
grouping adapted to develop exposed silver halide. A preferred silver 
halide development function is a hydroquinonyl group. 
Multicolor images may be obtained using the color image-forming components, 
for example, dye developers, in an integral multi-layer photosensitive 
element, such as is disclosed in the aforementioned U.S. patents and in 
U.S. Pat. No. 3,345,163 issued Oct. 3, 1967 to Edwin H. Land and Howard G. 
Rogers. A suitable arrangement of this type comprises a support carrying a 
red-sensitive silver halide emulsion stratum, a green-sensitive silver 
halide emulsion stratum and a blue-sensitive silver halide emulsion 
stratum, said emulsions having associated therewith, respectively, for 
example, a cyan dye developer, a magenta dye developer and a yellow dye 
developer. The dye developer may be utilized in the sliver halide emulsion 
stratum, for example in the form of particles, or it may be disposed in a 
stratum (e.g., of gelatin) behind the appropriate silver halide emulsion 
stratum. Each set of silver halide emulsion and associated dye developer 
strata preferably are separated from other sets by suitable interlayers. 
In certain instances, it may be desirable to incorporate a yellow filter 
in front of the green-sensitive emulsion and such yellow filter may be 
incorporated in an interlayer. However, if the yellow dye developer has 
the appropriate spectral characteristics and is present in a state capable 
of functioning as a yellow filter, a separate yellow filter may be 
omitted. 
For convenience, further description of this invention will be in the 
context of the use of dye developers and positive transfer images. Also 
for convenience, the disclosure of the aforementioned copending 
application, Ser. No. 33,001, now abandoned, is expressly incorporated 
herein.

Referring to the FIGURE, Stages A, B and C show in diagrammatic 
cross-section, respectively, imaging, processing, and the finished print 
in one embodiment of this invention. For ease of understanding, the FIGURE 
illustrates the formation of a monochrome image using a single dye 
developer. In Stage A, there is shown a photosensitive element 30 in 
superposed relationship with an image-receiving element 32, with a 
rupturable container 16 (holding an opaque processing composition 17) so 
positioned as to discharge its contents between said elements upon 
suitable application of pressure, as by passing through a pair of pressure 
applying rolls or other pressure applying means (not shown). 
Photosensitive element 30 comprises an opaque support 10 carrying a layer 
12 of a dye developer over which has been coated a silver halide emulsion 
layer 14. The image-receiving element 32 comprises a transparent support 
24 carrying, in turn, a polymeric acid layer 22, a spacer layer 20, an 
image-receiving layer 18 and a decolorizing layer 26. Photoexposure of the 
silver halide emulsion layer is effected through the transparent support 
24 and the layers carried thereon, i.e., the polymeric acid layer 22, the 
spacer layer 20, the image-receiving layer 18 and the decolorizing layer 
26, which layers are also transparent, the film unit being so positioned 
within the camera that light admitted through the camera exposure or lens 
system is incident upon the outer or exposure surface 24a of the 
transparent support 24. After exposure the film unit is advanced between 
suitable pressure-applying members, rupturing the container 16, thereby 
releasing and distributing a layer 17a of the opaque processing 
composition and thereby forming a laminate, as illustrated in processing 
Stage B, of the photosensitive element 30 and the image-receiving element 
32 with their respective support members providing the outer layers of the 
laminate (illustrated in Stage B). The opaque processing composition 
contains a film-forming polymer, a white pigment and has an initial pH at 
which one or more optical filter agents contained therein are colored; the 
optical filter agent (agents) is (are) selected to exhibit the appropriate 
light absorption, i.e., optical density, over the wavelength range of 
light actinic to the particular silver halide emulsion(s). As a result, 
ambient or environmental light within that wavelength range incident upon 
transparent support surface 24a and transmitted transversely through said 
transparent support and the transparent layers carried thereon in the 
direction of the exposed silver halide emulsion 14a is absorbed thereby 
avoiding further exposure of the photoexposed and developing silver halide 
emulsion 14a. In exposed and developed areas, the dye developer is 
oxidized as a function of the silver halide development and immobilized. 
Unoxidized dye developer associated with undeveloped and partially 
developed areas remains mobile and is transferred imagewise to the 
image-receiving layer 18 to provide the desired positive image therein. 
Permeation of the alkaline processing composition through the 
image-receiving layer 18 and the spacer layer 20 to the polymeric acid 
layer 22 is so controlled that the process pH is maintained at a high 
enough level to effect the requisite development and image transfer and to 
retain the optical filter agent (agents) in colored form within the 
processing composition layer 17a and on the silver halide emulsion side of 
said layer 17a, after which pH reduction effected as a result of alkali 
permeation into the polymeric acid layer 22 is effective to reduce the pH 
to a level which changes the optical filter agent to a colorless form. 
Absorption of the water from the applied layer 17a of the processing 
composition results in a solidified film composed of the film-forming 
polymer and the white pigment dispersed therein, thus providing reflecting 
layer 17b which also serves to laminate together the photosensitive 
component 30 and the image-receiving component 32 to provide the final 
laminate (Stage C). The positive transfer image in dye developer present 
in the image-receiving layer 18a is viewed through the transparent support 
24 and the intermediate transparent layers against the reflecting layer 
17b which provides an essentially white background for the dye image and 
also effectively masks from view the developed silver halide emulsion 14b 
and dye developer immobilized therein or remaining in the dye developer 
layer 12. 
The optical filter agent is retained within the final film unit laminate 
and is preferably colorless in its final form, i.e., exhibiting no visible 
absorption to degrade the transfer image or the white background therefor 
provided by the reflecting layer 17b. The optical filter agent may be 
retained in the reflecting layer under these conditions, and it may 
contain a suitable "anchor" or "ballast" group to prevent its diffusion 
into adjacent layers. Some of the optical filter agent may diffuse into 
the photosensitive component and be mordanted by the gelatin or other 
material present on the silver halide emulsion side of the reflecting 
layer 17b; optical filter mordanted in the photosensitive component 30 may 
be colorless or colored in its final state so long as any color exhibited 
by it is effectively masked by the reflecting layer 17b. In a preferred 
embodiment, the image-receiving element is free of gelatin; the 
photosensitive element contains gelatin, and the optical filter agent(s) 
is a pH-sensitive phthalein dye. 
In the illustrated embodiment, photoexposure is effected through the 
image-receiving element. While this is a particularly useful and preferred 
embodiment, especially where the photosensitive element and the 
image-receiving element are secured together as shown in U.S. Pat. Nos. 
3,415,644 and 3,647,437, it will be understood that the image-receiving 
element may be initially positioned out of the exposure path and 
superposed upon the photosensitive element after photoexposure. 
A light-absorbing material optical filter agent, preferably a pH-sensitive 
dye such as an indicator dye, is provided so positioned and/or constituted 
as not to interfere with photoexposure but so positioned between the 
photoexposed silver halide emulsions and the transparent support during 
processing after photoexposure as to absorb light which otherwise might 
fog the photoexposed emulsions. Furthermore, the light-absorbing material 
is so positioned and/or constituted after processing as not to interfere 
with viewing the desired image shortly after said image has been formed. 
In the preferred embodiments, the optical filter agent is initially 
contained in the processing composition in colored form together with a 
light-reflecting material, e.g., titanium dioxide. 
The concentration of indicator dye is selected to provide the optical 
transmission density required, in combination with other layers 
intermediate the silver halide emulsion layer(s) and the incident 
radiation, to prevent nonimagewise exposure, i.e., fogging, by incident 
actinic light during the performance of the particular photographic 
process. The transmission density and the indicator dye concentration 
necessary to provide the requisite protection from incident light may be 
readily determined for any photographic process by routine 
experimentation, as a function of film speed or sensitivity, processing 
time, anticipated incident light intensity, etc., as described in said 
U.S. Pat. No. 3,647,437. It will be recognized that a particular 
transmission density may not be required for all portions of the spectrum, 
lesser density being sufficient in wavelength regions corresponding to 
lesser sensitivities of the particular photosensitive material. 
In a particularly useful embodiment, the light-absorbing dye is highly 
colored at the pH of the processing composition, e.g., 13-14, but is 
substantially non-absorbing of visible light at a lower pH, e.g., less 
than 10-12. Particularly suitable are phthalein dyes having a pKa of about 
13 to 13.5; many such dyes are described in the aforementioned U.S. Pat. 
No. 3,647,437. This pH reduction may be effected by an acid-reacting 
reagent appropriately positioned in the film unit, e.g., in a layer 
between the transparent support and the image-receiving layer, as 
described in more detail below. 
It will be understood that a mixture of light-absorbing materials may be 
used so as to obtain absorption in all critical areas of the visible and 
near-visible by which the silver halide emulsions, e.g., a panchromatic 
black-and-white silver halide emulsion or a multicolor silver halide 
photosensitive element, being used are exposable. Many dyes which change 
from colored to colorless as a function of pH reduction, e.g., phthalein 
dyes, are known and appropriate selection may be made by one skilled in 
the art to meet the particular conditions of a given process and film 
unit; such dyes are frequently referred to in the chemical and related 
arts as indicator dyes. 
In accordance with this invention the optical filter agent(s) is a 
pH-sensitive phthalein dye and the decolorizing agent is a polyether, 
i.e., a polyoxyalkylene polymer, coated with another polymer which can 
form a hydrogen bond complex with the polyether to provide a decolorizing 
layer which is sufficiently "hard" to resist rub off and blocking. 
The polyether should be substantially non-diffusible from the decolorizing 
layer into the processing composition, thereby avoiding premature 
discharge of the optical filter agent in the processing composition layer. 
This factor may be controlled by selecting a higher molecular weight 
polyether or by selecting a polyether having a sufficient hydrocarbon 
group to reduce its diffusibility. The polyether should not be a liquid at 
room temperature. The preferred polyethers are waxes at room temperature. 
The ability of a given polyether to decolorize the particular optical 
filter agent(s) may be readily determined by a procedure such as the 
following: the optical filter agent in question is dissolved in 1.5 molar 
aqueous potassium hydroxide to provide a solution of about 0.01 weight 
percent of the optical filter agent in a test tube. The test decolorizing 
agent is added to the test tube in small increments. Decolorizing agents 
which decolorize or substantially reduce the visible absorption of the 
optical filter agent when added to the potassium hydroxide in quantities 
less than about 35 times (by weight) the optical filter agent 
concentration in said solution are preferred as they avoid the need to use 
undesirably high decolorizing layer coverages, e.g., such thickness as 
might undesirably slow down or reduce the transfer of image dye. 
As examples of polyethers useful in this invention, mention may be made of 
the polyoxyethylene polyoxypropylene block copolymer commercially 
available under the tradename "Pluronic F-127" from BASF Wyandotte Corp. 
(avarage molecular weight about 12,500) and the nonylphenyl terminated 
polyoxyethylene 
##STR1## 
sold under the tradename "Igepal CO-890" by GAF. 
As noted in the aforementioned copending application Ser. No. 33,001, now 
abandoned, Pluronic F-127 has been found effective with a number of 
phthalein dyes. Igepal CO-890 has been found to be at least as effective 
as Pluronic F-127, and to be more effective in decolorizing phthalein dyes 
such as: 
##STR2## 
The mechainism by which the decolorization occurs using the polyether is 
not a pH change. It has been determined that the addition of either Igepal 
CO-890 or Pluronic F-127 did not change the pH. It appears that the 
presence of a long chain substituent on the phthalein dye markedly reduces 
the quantity of the polyether required to effect the decolorization. It is 
believed that the polyether forms a complex with the phthalein dye which 
complex exhibits an apparent pKa higher than said phthalein dye in the 
alkaline processing composition. It also appears that phthalein dyes 
containing the grouping 
##STR3## 
are more readily decolorized by the polyether. 
As noted above, use of a polyoxyethylene polyoxypropylene block copolymer 
has been found to be useful in the practice of this invention. Such block 
copolymers may be represented by the formula 
##STR4## 
Varying the ratios a, b and c will vary the hydrophobic-hydrophillic 
balance of the block copolymer and such varying may be of value in the 
practice of this invention. Other polyoxyalkylene polymers, such as high 
molecular weight polyethylene glycol (m.wt. 6000) commercially available 
under the tradename Carbowax 6000 also may be used, although the above 
block copolymers are more effective. 
A particularly effective polymer hydrogen bonding a polyether decolorizing 
agent is a copolymer of diacetone acrylamide and methacrylic acid, 
preferably a 1:1 monomer ratio. Hydrogen bonding--a non-valent bonding--is 
believed to occur between the --COOH groups provided by the methacrylic 
acid and the oxygen of the ether group (--CH.sub.2 --CH.sub.2 
--O--CH.sub.2 --CH.sub.2 --). The diacetone acrylamide provides a 
hydrophobic property, and the ratio of the two monomers may be adjusted to 
provide the balance of hydrophillic and hydrophobic properties desired for 
a given photographic system. 1:1 copolymers of methacrylic acid and 
diacetone acrylamide having a molecular weight of about 10,000 to 20,000 
have been found to be particularly useful. The polymeric polyether 
preferably has a molecular weight of at least about 2000; the molecular 
weight in combination with the hydrophillic/hydrophobic properties of the 
polymeric polyether should be such as to render it substantially 
nondiffusible from the decolorizing layer. Where the ether groups do not 
hydrogen bond with sufficient --COOH groups to give the desired 
"hardness", e.g., because the molecular geometry does not provide the 
appropriate "fit", another hydrogen bonding polymer, e.g., polyvinyl 
pyrrolidone, may be incorporated. Hydrogen bonding also may occur between 
the carboxyl group and the amide groups. The particular hydrogen bonding 
group is not important, and suitable materials may be readily selected by 
routine experimentation. The hydrogen bonded complex should precipitate in 
water. The hydrogen bond is reversible in aqueous alkaline solution, thus 
making the polyether decolorizing agent available to complex with the 
phthalein optical filter agent and to permit rapid diffusion of the image 
dye (s) through the decolorizing layer to the image-receiving layer. 
As noted above, methacrylic acid is a preferred monomer in the hydrogen 
bonding polymer. Acrylic acid also may be used but is a less effective 
hydrogen bonding agent, possibly because fewer corboxyl groups are 
properly positioned to hydrogen bond with the polyether. The pendant 
methyl groups of the methacrylic acid moieties are believed to limit the 
ability of the carboxyl group to rotate around the polymer backbone, so 
that more of the carboxyl groups are properly positioned. 
In the preferred embodiment of this invention the decolorizing layer 
comprises a mixture of a 1:1 diacetone acrylamide/methacrylic acid 
copolymer, the nonyl phenol meno ether of a polyethylene glycol (n=40) 
(Igepal CO-890), and a low molecular weight polyvinyl pyrrolidone, e.g., 
"PVP K-30" polyvinyl pyrrolidone having a molecular weight of about 15,000 
and commercially available from GAF Corporation. Suitable ratios of these 
components, respectively, include 1.0/1.0/0.35 and 1.0/0.75/0.35 parts by 
weight. Such mixtures may be coated at a coverage of about 50 to 100 
mg./ft..sup.2 (about 538 to 1076 mg./m.sup.2. Suitable coating solvents 
include aqueous ethanol, to which may be added a ketone such as methyl 
ethyl ketone. The solvent system should be selected to avoid having an 
adverse effect upon the image-receiving layer and to minimize the 
formation of haze. Examples of suitable solvent systems for coating such 
decolorizing layers include (by volume) (1) and 80/20 water/ethanol 
mixture and (2) 50/35/15 acetone, ethanol and water. The DAA/MAA copolymer 
is added as the ammonium salt, with the free acid being regenerated during 
drying by volatilization of ammonia. 
The following examples of image-receiving elements empolying decolorizing 
layers in accordance with this invention are intended to be illustrative 
and are not intended to be limiting. All parts and percentages are by 
weight unless otherwise stated. 
EXAMPLE 1 
An image-receiving element was prepared by coating a transparent 
polyethylene terephthalate 4 mil (0.1 mm) support wih the following 
layers: 
1. a neutralizing layer comprising approximately 9 parts of a half-butyl 
ester of polyethylene/maleic anhydride and 1 part of polyvinly butyral 
coated at a coverage of about 2500 mg./ft.sup.2 (about 26,900 mg/m.sup.2); 
2. a timing layer comprising about 270 mg/ft.sup.2 (about 2900 mg/m.sup.2) 
of a 60.6/29/6.3/3.7/0.4 pentapolymer of butylacrylate, diacetone 
acrylamide, styrene, methacrylic acid and acrylic acid and about 30 
mg.ft.sup.2 (about 320 mg./ft.sup.2 of polyminyl alcohol; 
3. an image-receiving layer coated at a coverage of about 300 mg./ft.sup.2 
(about 3330 mg/m.sup.2 of a mixture of 3 parts of (a) a 2:1 mixture of 
polyvinyl alcohol and poly-4-vinyl pyridine and 1 part of (b) a graft 
copolymer comprising 4-vinyl pyridine (4VP) and vinyl benzyl trimethyl 
ammonium chloride (TMQ) grafted onto hydroxethyl cellulose (HEC) at a 
ratio HEC/4VP/TMQ of 2.2/2.2/1, and about 10 mg./ft.sup.2 (about 108 
mg/m.sup.2) of 1,4-butanediol diglycidyl ether cross-linking agent; and 
4. a decolorizing layer coated at a coverage of about 100 mg./ft.sup.2 
(about 1076 mg/m.sup.2) and comprising 1 part of a tetrapolymer of 
diacetone acrylamide, methacrylic acid, styrene and butyl acrylate at a 
ratio of 1/1/0.1/0.1, 0.75 part of Igepal CO-890 nonylphenoxyethylene 
oxide ethanol and 0.35 part of polyvinly pyrrolidone. 
EXAMPLE 2 
An image-receiving element was prepared as described in Example 1 except 
that the copolymer of diacetone acrylamide and methacrylic acid was 1:1. 
EXAMPLE 3 
An image-receiving element was prepared as described in Example 2 except 
that the ratio of the diacetone acrylamide/methacrylic acid polymer, 
Igepal CO-890 and polyvinyl pyrrolidone was 1/0.75/0.35. 
EXAMPLE 4 
An image-receiving element was prepared as described in Example 3 except 
that the neutralizing and timing layers were omitted. 
EXAMPLE 5 
An image-receiving element was prepared by coating a transparent subcoated 
polyethylene terephthalate 4 mil (0.1 mm) support with the following 
layers: 
1. an image-receiving layer comprising about 3170 mg/m.sup.2 of a graft 
copolymer of 2.2 parts 4-vinyl pyridine and 1 part vinyl benzyl trimethyl 
ammonium chloride on 2.2 parts of hydroxyethyl cellulose and about 43 
mg/m.sup.2 of 1,4-butanediol diglycidyl ether; and 
2. a decolorizing layer comprising about 1076 mg/m.sup.2 of a mixture of 1 
part 1:1 copolymer of diacetone acrylamide and methacrylic acid, 0.75 part 
Igepal CO-890, and 0.35 part of polyvinly pyrrolidone. 
When the above described image-receiving elements were used in an integral 
multicolor diffusion transfer process of the Polaroid SX-70 type using the 
following cyan, magenta and yellow dye developers 
##STR5## 
in a multilayer negative of the type described in said Ser. No. 33,001, 
using a layer approximately 0.0026 inch thick of a processing composition 
comprising: 
______________________________________ 
Water 40.80 g. 
Potassium hydroxide (100%) 4.59 g. 
Poly-diacetone acrylamide oxime 
0.67 g. 
Titanium dioxide 48.49 g. 
Benzotriazole 0.46 g. 
4-aminopyrazolo-(3,4d)-pyrimidine 
0.24 g. 
6-methyl uracil 0.25 g. 
N-2-hydroxyethyl-N,N',N'-tris- 
carboxymethyl-ethylene diamine 
0.63 g. 
Polyethylene glycol 
(mol. wt. about 4000) 0.38 g. 
bis-(.beta.-aminoethyl)-sulfide 
0.017 g. 
Colloidal silica 
(30% dispersion) 0.78 g. 
N-phenethyl-.alpha.-picolinium bromide 
1.07 g. 
##STR6## 1.31 g. 
##STR7## 0.29 g. 
______________________________________ 
good multicolor transfer images were obtained. The background provided by 
the layer of titanium dioxide appeared apparently substantially white to 
the viewer within 5 to 10 seconds after the processing composition was 
distributed between the image-receiving element, demonstrating that the 
decolorizing polyether had been effective. The decolorizing layers were 
found to be very resistant to rub off and blocking. 
Where the image-receiving element does not contain a neutralizing layer and 
a timing layer, as in Examples 4 and 5 above, these layers were coated in 
the photosensitive element between the opaque support and the cyan dye 
developer layer, as described in U.S. Pat. No. 3,573,043 issued Mar. 30, 
1971 to Edwin H. Land. 
In certain embodiments of this invention, the positive component 32 and the 
negative component 30 are temporarily laminated to each other so that the 
decolorizing layer 26 is in optical contact with the outer layer of the 
negative component 30. This bond should be of such a nature that these 
layers may be readily separated by the distribution of the processing 
composition following rupture of the pod 17. A particularly useful method 
of providing such a temporary lamination is to apply an aqueous solution 
of a polyethylene glycol, e.g., a polyethylene glycol having a molecular 
weight of about 6000 such as that commercially available under the 
tradename "Carbowax 6000" from Union Carbide Corporation. Such uses of 
polyethylene glycols are disclosed in U.S. Pat. No. 3,793,023 issued Feb. 
19, 1974 to Edwin H. Land and to which reference may be made. A 
particularly useful composition to provide such a temporary lamination is 
a 50:50 mixture by weight of Carbowax 6000 and Pluronic F-127. 
In certain preferred embodiments of this invention, the positive component 
32 and the negative component 30 are held in superposed relationship 
without being temporarily laminated together. In such embodiments the 
decolorizing layer also acts to prevent blocking of the positive and 
negative components in the integral film unit during storage prior to use. 
It is well known in the art that for in camera processing the processing 
composition should include a viscosity-increasing polymer of the type 
which, when the composition is spread and dried, forms a relatively firm 
and stable film. High molecular weight polymers are preferred, and include 
cellulosic polymers such a sodium carboxymethyl cellulose, hydroxyethyl 
cellulose and hydroxyethyl carboxymethyl cellulose. Another class of 
useful viscosity-increasing polymers comprises the oxime polymers 
disclosed and claimed in the copending application of Lloyd D. Taylor, 
Ser. No. 894,545 filed Apr. 7, 1978 (now U.S. Pat. No. 4,202,694 issued 
May 13, 1980). Suitable oxime polymers include polydiacetone acrylamide 
oxime as well as copolymers, e.g., grafts of diacetone acrylamide oxime 
onto hydroxyethyl cellulose. It has been found that the decolorizing of 
the optical filter agent immediately adjacent the interface is 
particularly effective when the concentration of the viscosity-providing 
polymer is about 1% by weight or less, e.g., about 0.8% by weight as in 
the above examples. 
Neutralizing layers such as the polymeric acid layer are well known in the 
art and are described in detail, for example, in the above-noted U.S. Pat. 
Nos. 3,415,644, 3,573,043 and 3,647,437 to which patents reference may be 
made. 
It will be understood that the concentration of the decolorizing agent is 
such that in the absence of a pH neutralizing mechanism, such as the 
polymeric acid layer, the decolorizing agent is insufficient to discharge 
or "clear" all of the optical filter agent present. Thus, if the polymeric 
acid layer is omitted one observes that the optical filter agent adjacent 
the processing composition interface is decolorized but the color of the 
optical filter agent reappears after a period of time, presumably due to 
later diffusing optical filter agent. 
This invention is applicable to a wide variety of photographic processes as 
will be readily apparent to one skilled in the art. Dye developers are 
preferred image-providing substances, as indicated above, and constitute 
an example of initially diffusible dye image-providing substances. Other 
useful dye image-providing substances include initially diffusible dyes 
useful as image dyes per se and which couple with the oxidation product of 
a silver halide developing agent to provide a non-diffusible product, 
initially diffusible color couplers which couple with the oxidation 
product of a silver halide developing agent to provide image dyes, 
initially non-diffusible compounds which react with the oxidation product 
of a silver halide developing agent, as by coupling or by cross-oxidation, 
to release a diffusible dye useful as an image dye per se. The final image 
may be formed as a result of the diffusion transfer of a soluble complex 
of undeveloped silver halide, in which event the image may be in silver as 
is well known. In another dye release system a soluble silver complex 
formed from undeveloped silver halide may be used to effect a cleavage 
reaction and release a dye or dye intermediate for transfer. Since these 
image-forming processes are well known and form no part per se of the 
present invention, it is not necessary to describe them in detail herein. 
It will be understood that the transfer image may be positive or negative, 
with respect to the photographed subject matter, as a function of the 
particular image-forming system employed. The silver halide emulsion may 
be negative-working or positive-working (e.g., internal latent image) as 
appropriate for the particular imaging system. 
For convenience, the disclosures of the aforementioned U.S. Pat. Nos. 
3,415,644, 3,575,043 and 3,647,437 are expressly incorporated herein. 
Since certain changes may be made in the above product and process without 
departing from the scope of the invention herein involved, the invention 
is not intended to be limited thereto but to include variations and 
modifications obvious to those skilled in the art and which are within the 
spirit of the invention and the scope of the appended claims.