US3721562A - Integral laminate photographic units comprising developing composition-spreader sheets containing a polymeric acidifying layer - Google Patents

Abstract

Novel system for forming visible images wherein an aqueous alkaline processing composition is applied between a first sheet comprising a photosensitive element and a second sheet including an acid-neutralizing layer, said sheets being adapted for being maintained together after application of the processing composition. In a preferred embodiment, a system is disclosed for forming negative images wherein a developed and fixed negative image in silver is provided with a transparent overlay through which the image may be viewed. In another disclosed embodiment, an image in color, which may be a positive transfer image, is provided with such a transparent overlay.

Description

United States Patent [1 1 Land [ 1March 20, 1973 INTEGRAL LAMINATE PHOTOGRAPHIC UNITS COMPRISING DEVELOPING COMPOSITION- SPREADER SHEETS CONTAINING A POLYMERIC ACIDIFYING LAYER [75] Inventor: Edwin H. Land, Cambridge, Mass.-v

[73] Assignee: Polaroid Corporation, Cambridge,

Mass.

[22] Filed: July 29, 1971 [211 App]. No.: 167,455

Related U.S. Application Data [63] Continuation-in-part b? Ser. 'NoI 888,919,

Dec. 29 1969.

[52] [1.8. C]. ..96/61 M, 96/3, 96/29 D, 96/29 R, 96161 M, 96/66 R [51] Int. Cl ..G03c 5/38, G030 5/54, G03c 7/00 [58] Field of Search ..96/3, 29 R, 29 D 56] References Cited UNITED STATES PATENTS 3,362,819 Land ..96/3

3,549,364 12/ i970 Morse ..96/29 R Primary Examiner-J. Travis Brown Assistant Examiner-Alfonso T. SuroPico Attorney-Charles Mikulka et al.

[57] ABSTRACT 7 Novel system for forming visible images wherein an I transfer image, is provided with such a transparent overlay.

22 Claims, No Drawings INTEGRAL LAMINATE PI'IOTOGRAPHIC UNITS COMPRISING DEVELOPING COMPOSITION- SPREADER SHEETS CONTAINING A POLYMERIC ACIDIFYING LAYER This is a continuation in part of application Ser. No. 888,919 filed Dec.29, 1969.

BACKGROUND OF THE INVENTION U.S. Pat. No. 3,343,958 discloses a one-step system for forming a developed and fixed negative image which requires no stabilizing aftertreatment, e.g., washing to remove spend processing composition and/or printcoating. According to this patent, a photosensitive element comprising a light-sensitive silver halide layer is exposed to form a developable image and the thus exposed element is then developed with an aqueous alkaline processing composition containing at least one silver halide developing agent and a silver halide solvent system which will fix the developed image by forming from undeveloped silver halide a transparent silver complex which will not subsequently precipitate as image silver. The silver halide solvent system employed to form this stable, transparent silver complex consists essentially of the combination of cysteine (aamino-B-mercaptopropionic acid) and a nitrogenous base, preferably a volatile nitrogenous base. Examples of useful nitrogenous bases include: ammonia, sec. amylamine, ethylamine, n-butyl-amine, allylamine, diethylamine, dipropylamine, trimethylamine, triethanol amine, diethylene triamine, triethylene tetramine, N-hydroxyethyl propylene diamine, trimethylene diamine, ethylene diamine, aminoethyl ethanol amine, hydroxyethyl diethylene triamine, tetraethylene pentamine, quanidine hydrochloride, piperidine, pyrrolidine, 2,5-dimethyl piperazine, polyethylene imine, symmetrical dimethyl hydrazine and unsymmetrical dimethyl hydrazine.

This silver halide solvent system is preferably employed in processing compositions including the silver halide developing system described and claimed in the application of Meroe M. Morse, Ser. No. 438,044, filed Mar. 8, 1965 and which was abandoned in favor of application Ser. No. 690,728, filed Dec. 15, 1967, now U.S. Pat. No. 3,549,364 as a continuation-in-part thereof. As is disclosed in these applications, the necessity for some aftertreatment, e.g., washing, to prevent the harmful effects resulting from the presence of exhausted and/or unexhausted developing agent is greatly reduced, if not obviated, by employing as the developing system the combination of a high concentration of a low-energy silver halide developing agent and an extremely low concentration of a high-energy silver halide developing agent.

Many so-called high-energy developing agents are known in the art. Preferred are the aminophenols, particularly 4-aminophenols containing a lower alkyl, lower alkoxy and/or amino group in a position or positions ortho to the hydroxyl group. Particularly useful examples of such high-energy silver halide developing agents include 2,4-diaminoortho-cresol, 4-amino-2,6-

dimethyl-phenol and 2,6-dimethoxy-4-amino-phenol.

Other examples of suitable high-energy silver halide developing agents may be found in U.S. Pat. Nos. 3,091,530, 3,108,001 and others.

Particularly useful low-energy silver halide developthose which have substantially colorless oxidation products and/or are volatilized from the image, particularly the ascorbic acids, such as ascorbic acid, isoascorbic acid, etc., and hydroxylamines, e.g., N,N-diethylhydroxylamine, and N.,N,-dimethoxyethyl-hydroxylamine. N,N- dimethoxyethyl-hydroxylamine. hydroxylamine silver halide developing agents include those disclosed in U. S. Pat. Nos. 2,857,276, 3,287,125 and others.

As stated above, the high-energy silver halide developing agent is used in extremely low concentrations, i.e., a concentration ineffective, if used as the sole developing agent, to develop appreciable negative density, e.g., less than about 0.3, within the predetermined, usually very short, processing period. Although the low-energy silver halide developing agent is used in substantial concentrations, it too is ineffective to develop appreciable negative density within the predetermined processing period if used in that concentration as the sole developing agent. However, this ing an exposed silver halide emulsion to obtain a silver image of excellent density and detail without leaving any reagents capable of impairing the quality of the image.

In addition to the foregoing ingredients, processing compositions employed in such systems for forming a developed and fixed negative image may contain an alkaline material necessary for initiating development such as sodium or potassium hydroxide, sodium carbonate, etc., and they may contain other ingredients performing specific desired functions, e.g., a viscous film-formingreagent such as hydroxyethyl cellulose, sodium carboxymethyl cellulose, etc., antifoggants, toning agents and the like. In systems employing the aforementioned. silver halide solvent system, the processing composition may also contain a small amount of sodium or potassium thiosulfate, which, as is disclosed in the aforementioned U.S. Pat. No. 3,343,958 has been found to lower appreciably the imbibition time necessary to obtain a fixed negative image of the desired density and contrast.

To prepare a negative image with the above-mentioned processing compositions, the exposed photosensitive element is contacted with the processing composition for a suitable period of time to develop and fix the image. A particularly useful procedure for applying the processing composition is by spreading the composition containing the viscous reagent in a substantially uniform layer between the thus exposed element and a superposed spreader sheet. After the development period, the spreader sheet is removed to reveal the developed and fixed negative image. Such procedures employing a spreader sheet are disclosed, for instance, in the illustrative examples of the aforementioned patent and applications.

In the procedures described above, following development it is necessary to separate the spreader sheet to reveal the image. This spreader sheet is then discarded, thereby requiring the photographer to find a place to deposit it until it may be disposed of. The objections to storing it in ones pocket or carrying a spe- N,N-diethoxyethyl-hydroxylamine,

cial litter container will be apparent. It would therefore be desirable. to device a system which obviates these objectional features.

It was first thought that this could be accomplished by employing as the spreader sheet one of the known transparent sheet materials which would be retained on V the negative image to provide as the final product a sheet and the superposed photosensitive element to ef-' fect development, after a short period of time the reagent dries sufficiently to act as an adhesive effectively bonding and retaining these materials in superposition. It was found, however, that in such a lamination or sandwich, after a relatively short period of time, e.g., 24 hours, tiny pin holes appeared in the silver areas of the negative image, producing minute transparent areas which reproduced in positive prints obtained therefrom as corresponding tiny black dots in the highlight areas of the print. In other words, while a negative image produced in accordance with the teachings of the aforementioned patent and application was extremely stable, as evidenced by the fact that such negatives with no aftertreatment were found to exhibit no density fading or density increase in highlights when stored for over two years, when the final product was in the form of a sandwich containing the transparent overlay, something happened which caused removal of image silver to produce the tiny transparent dots mentioned previously. The exact reason for this phenomenon is not clearly understood. However, it is believed to be initiated by the fact that the processing composition is confined and hence removal of moisture and resulting drying time is materially extended over systems wherein the surface of the developed negative is fully exposed to air.

One embodiment of this invention is directed towards obviating this problem so as to provide a stable developed and fixed negative image provided with a transparent overlay through which the image may be viewed.

Procedures have also heretofore been known wherein a visible image in color is obtained by developing an exposedphotosensitive element comprising at least one light-sensitive silver halide layer having a dye image-providing material associated therewith with an aqueous alkaline processing composition. Multicolor images are so obtained by employing photosensitive elements containing more than one such silver halide layer and associated dye image-providing material, the preferred such film unit for forming multicolor images being of the so-called tripack configuration including a blue-, a greenand a red-sensitive silver halide layer having associated therewith, respectively, a yellow, a magenta, and a cyan dye im age-forming material which may be a complete dye or a dye intermediate, e.g., a color coupler. Such color processes generally speaking may be referred to as being additive or subtractive color systems. A particularly useful system for forming color images is one of the known color diffusion transfer systems wherein an exposed film unit of the foregoing description is developed to provide, as a function of such exposure and development, an imagewise distribution of mobile and diffusible dye image-providing material which is then transferred, at least in part, by diffusion, to a superposed dyeable stratum to impart thereto a color transfer image which may be a positive or a negative color image, depending upon the particular photographic system employed. In general, the dye image-providing materials employed in such color processes may be defined as being either initially mobile and diffusible materials which are selectively rendered immobile or non-diffusible; or initially immobile and non-diffusible materials which are selectively rendered mobile and diffusible as a function of development. As examples ofthe former type of imageproviding materials and systems employing them to prepare color images, mention may be made of those disclosed, for example, in U.S. Pat. Nos. 2,647,049; 2,661,293; 2,698,244; 2,698,798; 2,802,735; 2,774,668; and 2,983,606; as examples of thelatter type of image-providing materials and systems employing them to prepare color images, mention may be made of those disclosed, for example, in U.S. Pat. Nos. 3,443,939; 3,443,940; 3,227,550; 3,227,551; 3,227,552; 3,227,554; 3,243,294; and 3,445,228.

One particularly useful class of dye image-providing materials are dye developers, i.e., dyes which are also silver halide developing agents. Photographic systems employing dye developers are disclosed in the aforementioned U.S. Pat. No. 2,983,606 as well as in many subsequently issued patents and since such photographic systems are well known in the art, further detailed description is not necessary.

It is also advisable to adapt these color systems of the processing composition, it has been found that the stability and/or quality of the resulting image suffersunless means are provided for lowering the pH after sub-- stantial development and color image formation has been completed. To accomplish this objective it has heretoforebeen suggested that the film unit contain an acid neutralizing layer, e.g., apolymeric acid layer. Color systems employing such pH-reducing means are disclosed,for example, in U. S. Pat. No. 3,362,819. In diffusion transfer systems, this layer is usually associated with the dyeable stratum or image-receiving layer, although systems are also known wherein the acid-neutralizing layer is associated with the photosensitive strata, e.g., with the silver halide layer or layers.

It is to such systems wherein an alkaline processing composition is applied between a first sheet material comprising an exposed photosensitiveelement and a second sheet material or spreader sheet to provide a visible image, that this invention is directed.

SUMMARY OF THE INVENTION In accordance with this invention, the aforementioned problems in the various film systems such as those described above are obviated by employing as the second (spreader) sheet or overlay, a sheet material, preferably transparent for viewing purposes, having a layer of a material which will remove, neutralize or otherwise render innocuous a sufficient quantity of unexhausted alkaline material following development and substantial image formation. This layer may be a polymeric acid layer of the type described in the aforementioned U. S. Pat. No. 3,362,819.

DESCRIPTION OF PREFERRED EMBODIMENT In the preferred embodiment this layer contains a polymeric acid and means are also provided for preventing premature interaction between the alkaline ions and the polymeric acid, i.e., pH reduction prior to development of the exposed photosensitive element. In a particularly preferred form, the polymeric acid is disposed in a layer between the transparent sheet material and an inert alkali-permeable spacer layer which serves to time control diffusion through this layer to the underlying polymeric acid layer and subsequent pH reduction.

As was mentioned previously, this invention relates to photography and, more particularly, to photographic procedures which are litter-free, namely do not involve the use in the development process of materials which must latter be discarded, thereby avoiding all of the inconveniences inherent in prior systems of this nature.

A primary object of this invention is to provide novel photographic procedures of the foregoingdescription.

Another object is to provide novel systems wherein a photosensitive element or film unit is developed by applying a viscous aqueous alkaline processing solution between the exposed element and a superposed second or spreader sheet including an acid-neutralizing layer to provide, as the desired photographic print, a sandwich" comprising the visible image formed as a function of development and the superposed spreader sheet, which image is viewable without separation of the respective sheets.

Another object is to provide novel procedures wherein an exposed photosensitive element is developed and fixed in a single step by spreading an aqueous alkaline processing composition between the thus exposed element and a superposed transparent element to provide, as the final product, a highly stable negative image in the form of a sandwich consisting essentially of the developed and fixed negative image, the surface of which is adhered to the transparent element through the adhesive action of the spent or exhausted processing composition interposed therebetween.

Still another object is to provide a novel process wherein a photosensitive element comprising a lightsensitive silver halide layer is exposed to form a developable image; the thus exposed element is then developed and fixed in a single step by spreading between the exposed element and a superposed transparent element comprising a transparent sheet material bearing on the side to be placed closest to the photosensitive element a polymeric acid layer, a viscous aqueous alkaline processing composition containing a silver halide solvent system comprising the mixture of cysteine and a nitrogenous base and a silver halide developing system comprising the combination of a small amount of a high-energy silver halide developer and a large amount of a low-energy silver halide developing agent; and the respective elements are retained in superposition as the final product.

Yet another object is to provide a sandwich of the foregoing description including a photographic image in color. I

A still further object is to provide a positive color transfer image having a transparent overlay of the foregoing description through which the color image may be viewed.

Other objects of the present 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.

As was mentioned previously, the present invention is directed to'photographic procedures wherein an exposed photosensitive element is developed by applying an alkaline processing composition between the exposed element and a superposed spreader sheet to provide a visible image which may be viewed without separation of this spreader sheet. The present invention therefor contemplates systems wherein a spreader sheet is employed to facilitate application of a viscous alkaline processing composition in a substantially uniform layer over the surface of the film unit to initiate development and thereafter need not be discarded. I

One photographic system particularly contemplated by this invention is the one-step system for forming a developed and fixed negative image described in U. S. Pat. No. 3,343,958 and described with more particularity in the Background of the Invention. As was also mentioned in the Background of the Invention, when a conventional transparent sheet material is employed as this spreader sheet, instability of the negative image occurs. This instability manifests itself in a relatively short period of time, say, for example, after 24 hours as tiny transparent dots or pin holes in the areas of developed silver, which reproduce in positive prints obtained therefrom as tiny black dots in the highlight (non-image) areas. In accordance with the present invention it has been discovered that this.

problem may be effectively obviated by employing as the spreader sheet a transparent sheet material having a layer to which the alkaline ions may diffuse following development and be captured and retained in place, e.g., by' neutralization. This layer may, for example, comprise a polymeric acid. Stated another way, the essence of the present invention is the discovery that the problem of pin holes in silver areas of the negative image formed by applying the viscous processing fluid between the exposed photosensitive element and the superposed spreader sheet and retaining these elements in superposition as the final product, may be obviated by employing as this spreader sheet an elementincluding means for lowering the pH of the spent processing fluid to at least about pH 8 and preferably below pH after image formation.

The spreader sheet (transparent overlay) contemplated for use in this invention comprises a transparent sheet material, for example, a transparent plastic such as polyethylene terephthalate, a vinyl resin, e.g., a copolymer of vinyl acetate and vinyl chloride, a cellulose ester such as cellulose acetate, cellulose triacetate, cellulose butyrate, etc., carrying a polymeric acid layer which removes alkaline ions and lowers the pH by diffusion of these ions from the surface of the negative image and/or the processing fluid to this layer where they are precipitated.

Useful polymeric acids include various polymers containing carboxylic or sulfonic acid groups which are capable of forming salts with the alkaline ions, as well as polymers containing potential acid-yielding groups, such as anhydrides, lactones, etc. The acid polymers found to be most useful are characterized by containing free carboxyl groups, being insoluble in water in the free acid form, and by forming water-soluble sodium salts. One may employ polymers containing carboxylic acid anhydride groups, at least some of which preferably have been converted to free carboxyl groups prior to imbibition. While the most readily available polymeric acids are derivatives of cellulose or of vinyl polymers, polymeric acids from other classes of polymers may be used. As examples of specific polymeric acids contemplated as being used in this invention, mention may be made of dibasic acid halfester derivatives of cellulose, which derivatives contain free carboxyl groups, e.g., cellulose acetate hydrogen phthalate, cellulose acetate hydrogen glutarate, cellulose acetate hydrogen succinate, ethyl cellulose hydrogen succinate, ethyl cellulose acetate hydrogen succinate, cellulose acetate hydrogen succinate hydrogen phthalate; ether and ester derivatives of cellulose modified with sulfoanhydrides, e.g., with orthosulfobenzoic anhydride; polystyrene sulfonic acid; carboxymethyl cellulose; polyvinyl hydrogen phthalate; polyvinyl acetate hydrogen phthalate; polyacrylic acid; acetals of polyvinyl alcohol with carboxy or sulfo substituted aldehydes, e.g., 0-, m-, or p-benzaldehyde sulfonic acid or carboxylic acid; partial esters of ethylene/maleic anhydride copolymers; partial esters of methylvinyl ether/maleic anhydride copolymers; etc.

It will be appreciated that the pH-reducing action by the polymeric acid should be controlled so as not to interfere with the development step. In order to prevent premature pH reduction, the acid groups are preferably distributed in the acid polymer layer'such that the rate of their availability to the alkali is controllable, e.g., as a function of the rate of swelling of the polymer layer, which rate in turn has a direct relationship to the diffusion rate of the alkali ions. The desired distribution of the acid groups in the acid polymer layer may be effected by mixing the-acid polymer with a polymer free of acid groups or lower in concentration of acid groups and compatible therewith, or by using only the acid polymer, but selecting one having a relatively lower proportion of acid groups.

In the preferred embodiment of this invention, an inert spacer layer or timing layer is provided over the polymeric acid layer to obtain still further improvements in control of the pH reduction by the polymeric acid layer. This spacer layer comprises a polymer, or mixture of polymers, inert to alkali but through which the alkaline ions may diffuse to the polymeric acid layer. As examples of useful polymeric materials for this timing layer, mention may be made of polyvinyl alcohol, a partial acetal of polyvinyl alcohol, e.g., partial polyvinyl butyral, gelatin, a cyanoethylated polyvinyl alcohol, a polyvinyl amide, a graft polymer, e.g., a polyvinyl amide graft polymer such as the graft copolymer of diacetone acrylamide and acrylamide on polyvinyl alcohol, etc.

Polymeric acid layers and timing layers of the foregoing description have heretofore been contained on image-receiving elements further containing a dyeable stratum and hence are heretofore known in the art of color diffusion transfer photography. Accordingly, such layers per se comprise no part of this invention. As examples of patents pertaining to color im age-receiving elements containing such layers, mention may be made of U. S. Pat., No. 3,362,819 issued to Edwin H. Land;

No. 3,419,389 issued to Howard C. Haas and Henry S.

Kolesinski; No. 3,421,893 issued to Lloyd D. Taylor; and No. 3,433,633 issued to Howard C. Haas. Timing layers comprising a polyvinyl amide graft copolymer, mentioned previously, are described and claimed in the copending application of Lloyd D. Taylor, Ser. No. 790,747 filed Jan. 13, 1969, now U.S. Pat. No. 3,575,701.

In a preferred form of this invention, the processing composition is contained in a frangible or rupturable container of the type heretofore known in the art and disclosed for example, in U. S. Pat. Nos. 2,543,181 and 2,634,886, issued to Edwin H. Land.

To prepare a negative image according to this invention, an exposed photosensitive element comprising a light-sensitive silver halide layer is developed by applying a viscous aqueous alkaline processing composition of the type previously described between the thus exposed element and a superposed transparent element of the foregoing description. After a suitable development time, e.g., 30 seconds, a fully developed and fixed negative image is obtained. The spreader sheet which was adhered to the surface of this negative image is retained as an integral part of the finished product, rather than being a waste material requiring disposal. Negatives prepared in accordance with this invention have been found to be highly stable, requiring no aftertreatment. They may be employed subsequently in standard photographic techniques for obtaining one or more positive prints of the original subject matter.

The following examples show by way of illustration and not by way of limitation the practice of this invention.

EXAMPLE 1 A photosensitive element having a gelatino silver halide emulsion on a transparent film base was exposed and then developed by spreading between the thus exposed emulsion and a superposed subcoated cellulose triacetate spreader sheet, at a gap of 0.0022, a viscous processing composition containing the following proportions of ingredients:

Water 902.0 cc Hydroxyethyl cellulose 4L5 g. Sodium sulfite 33.0 3. Potassium thiosulfate 14.0 g.

Ascorbic acid 60.0 g. 2,4-diamino-orthocresol 2.0 g. cysteine 2.2 g. diethylamine 50.0 cc. Sodium hydroxide 25.0 g.

After an imbibition time of about 30 seconds, an excellent negative image was obtained. The spreader sheet was retained on the negative and the resulting sandwich was stored at room temperature. After about 24 hours tiny pin holes were observed in the areas of developed silver. These tiny transparent areas reproduced as corresponding tiny black dots in the highlight areas of positive prints obtained from this negative image. 1

EXAMPLE 2 A spreader sheet was prepared by applying to the subcoated surface of a cellulose triacetate sheet an aqueous solution comprising 70 parts by weight of poly-(. ethylene/maleic anhydride) [commercially available from Monsanto Chemical Co. as DX Resin Grade 840-1 l-03] and 30 parts by weight ofElvanol 70-05 (trademark of E. I. duPont de Nemours and Co. for a low viscosity, completely hydrolyzed polyvinyl alcohol). The solution was dried to provide a polymeric acid layer about 0.4 mil. thick. Over this was applied a timing layer about 0.15 mil. thick comprising a graft copolymer of diacetone acrylamide and acrylamide on polyvinyl alcohol prepared in the manner described in the aforementioned copending application, Ser. No. 790,747. The procedure of Example 1 repeated, substituting this spreader sheet for the spreader sheet employed in Example 1, the processing fluid being spread between the exposed photosensitive element and the coated side of the spreader sheet. An excellent image similar to that obtained in Example 1 was formed. Again, the spreader sheet was retained as an integral part of the final product. Negative images prepared in the manner described in this example failed to exhibit the pin hole effect after months of storage, thereby indicating that the stability problem illustrated in Example 1 had been obviated.

EXAMPLE 3 A negative image containing the transparent overlay prepared as in Example 2 was subjected to a standard heat-humidity storage test by storing it for 40 hours at separation of the spreader sheet from the film unit or' photosensitive element containing the image. Preferred systems of this nature are those wherein a color image is imparted, by diffusion transfer, to a dyeable stratum and a white reflecting agent is provided between the thus formed image and the photosensitive strata, e.g.,

. on the side of the dyeable stratum opposed from the viewing surface of the film unit, so that the color image can be viewed, without separation, as a reflection print. As an example of such color systems, mention may be made of those described in the copending applications of Howard G. Rogers, Ser. No. 39,646, now US. Pat. No. 3,594,165, and Ser. No. 39,666, now US. Pat. No. 3,594,164, both filed May 22, 1970. These applications disclose systems wherein a processing composition is applied between a dimensionally stable support layer, e.g., spreader sheet, and the coated surface of a photosensitive element including at least one light-sensitive silver halide layer and associated dye imageproviding material, a layer of reflecting agent, e.g., a white pigment, and, a dyeable stratum contained on a dimensionally stable transparent support member, to v I provide a color transfer image viewable, by reflected light, through the transparent support member of the photosensitive element. In such systems, it is often desirable, if not necessary, for image stability and/or optimum image quality, to provide neutralizing means to lower the pH after substantial color image formatiori. The present invention provides such neutralizing 1 the use of the present invention in color photography,

the color image so formed being a transfer image viewable, without separation, as a reflection print.

EXAMPLE 4 Over the coated surface of a conventional type multicolor negative employing dye developers and comprising an opaque support material containing the following layers:

a layer of a cyan dye developer, 1,4-bis-(B- hydroquinonyl-a-methyl-ethylamino)-5 ,8-dihydroxyanthraquinone dispersed in gelatin;

2. a red-sensitive gelatino silver iodobromide emulsion;

3. a gelatine interlayer;

4. a layer of a magenta dye developer, 2-(p-[B- hydroquinonylethyl l-phenylazo )-4-isopropoxyl naphthol dispersed in gelatin;

5. a green-sensitive gelatino silver iodobromide emulsion;

6. a gelatin interlayer;

7. a layer of a yellow dye developer 4-(p-[B- hydroquinonylethyl]-phenylazo)-3-(N-hexylcarboxamido)-1-phenyl-5-pyrazolone dispersed in gelatin;

8. a blue-sensitive gelatino iodobromide emulsion; and

9. a layer containing 4-methylphenyl hydroquinone dispersed in gelatin was coated the following additional layers:

10. a white reflecting layer containing about 650 mgs./ft. of titanium dioxide; 55 mgsJft. of gelatin; and 15 mgs./ft. of CAB-O-SIL (trademark of Godfrey L. Cabot for a fire-dry 99 percent pure fumed silica with a particle size of 0.015 micron); and

11. a dyeable stratum comprising a 2:1 mixture, by

weight, of polyvinyl alcohol and poly-4-vinylpyridine, and including a development restrainer, l-phenyl-S- mercaptotetrazole to provide a multicolor film unit containing the photosensitive strata and associated dye image-providing material and the dyeable stratum or receiving layer separated by a layer of white reflecting agent. This film unit was then exposed through the coated surface and then developed by applying between the thus exposed element and the coated surface of a spreader sheet comprising a transparent polyester base containing a 72.5 mixture, by weight, of polyethylen elmaleic anhydride copolymer and polyvinyl alcohol at a coverage of about 1,000 mgs./ft., as the acid-neutralizing layer, and a spacer layer comprising a 1:9 mixture of styrene/maleic anhydride copolymer and vinyl acetate at a coverage of about 1,000 mgs./ft., at a gap of about 0.0050 inch, a processing fluid containing the following proportions of ingredients:

to provide a multicolor image viewable the spreader sheet as a positive reflection print. When compared with a control prepared in the same manner except the spreader sheet was a standard transparent sheet containing no neutralizing layer, the aforementioned print (prepared with a spreader sheet including an acidneutralizing layer in accordance with this invention) was significantly better, particularly in the rendering of the blues, greens and cyans.

The present invention is also useful in systems for preparing composite prints comprising superposed negative and positive silver images as well as in additive color processes which may employ this concept and wherein the film unit is exposed through an optical screen, e.g., a trichromatic additive color screen of the conventional type to form a developable image and is then developed with an aqueous alkaline processing fluid including a silver halide solvent to form a negative silver image and a silver transfer image of greater density or covering power than the negative image in a superposed stratum. The resulting composite print may then be viewed as a color image by light transmitted through the optical screen. Additive color reproduction systems employing silver diffusion transfer techniques are per se known and are described, for example, in U. S. Pat. Nos. 2,726,154 and 2,944,894,

both issued to Edwin H. Land.

By way of illustration a film unit including a transparent support carrying an additive color screen, a silver receptive stratum of known description having description including an acid-neutralizing layer. Fol-- lowing development, if the spreader sheet is transparent, it may be left intact and the resulting structure may then be viewed by transmitted light as a color transparency. Film units of the foregoing description comprising a permanently fixed laminate including a support carrying on one surface thereof an additive color screen, photosensitive silver halide and silver precipitating nuclei are described with greater particularity, for example, in U. S. Pat. No. 3,536,488 issued to Edwin H. Land on Oct. 27, 1970; copending applications Ser. No. 889,656, now US. Pat. No. 3,615,427 and Ser. No. 889,636, now US. Pat. No. 3,615,426 both in the name of Frank E. Debruyn, Jr.; and copending applications Ser. No. 889,657, now US. Pat. No. 3,615,428 and, Ser. No. 889,660, now US. Pat. No. 3615,429 both in the name of Lucretia J. Weed, all filed Dec. 31, 1969.

By way of further illustration such a film unit may comprise a transparent polyester support carrying on one side thereof, in order, a trichromatic additive color screen of a conventional type having about 500 lines to the inch, a silver receptive stratum comprising copper deacetylated chitan and 0.25 mgs./ft. coppersulfide,

and a gelatino silver iodochlorobromide emulsion. In accordance with this invention the film unit may beex posed through the screen to provide a developable image and then developed by applying a processing fluid of known description including an alkaline material such as sodium or potassium hydroxide, a silver halide developing agent such as the known hydroquinones, p-aminophenols, etc., and a silver halide solvent such as sodium or potassium thiosulfate, sodium thiocyanate, ammonium thiocyanate, etc., between the thus exposed film unit and the coated surface of a spreader sheet comprising a polyester base having coated thereon a neutralizing layer comprising a 7:3 mixture of polyethylene/maleic anhydridecopolymer and polyvinyl alcohol at a coverage of about 1,000 mgs./ft. and a spacer layer comprising a 1:9 mixture of styrene/maleic anhydride copolymer and vinyl acetate at a coverage of about 1,000 mgs./ft. Following development the transparent spreader sheet may be retained with the film unit and a resulting sandwich may be employed in known manner by light transmitted through the screen to provide a positive color reproduction of the original subject matter.

While the preferred photographic systems contemplated by this invention employ a transparent sheet, as was mentioned previously it is also contemplated that one may in certain systems employ an opaque spreader sheet. It will be appreciated, however, that where transparencies are contemplated, the opaque spreader sheet must be separated following image formation for viewing. lnsystems providing reflection prints, the opaque spreader sheet must also be separated where the print is to be viewed by reflected light from the surface of the film unit in superposition with the spreader sheet. Where the print is to be viewed by reflected light through a transparent support for the film unit, however, the opaque spreader sheet may be retained. An opaque spreader sheet contemplated by this invention may be prepared by coating on an opaque cellulose Since certain changes may-be made in the above product and process without departing from'the scope of the invention herein involved, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a photographic process for preparing visible images wherein an exposed photosensitive element ineluding a silver halide layer containing a developable image is developed by applying an aqueous alkaline processing composition between the thus exposed element and a superposed spreader sheet employed to facilitate application of said processing composition and to form a visible image only in said photosensitive element, the improvement which includes employing as said spreader sheet a sheet material containing a reagent for substantially lowering the pH of said processing composition following substantial image formation, said spreader sheet being retained in superposition following formation of said image.

2. A process as defined in claim 1 wherein said spreader sheet is transparent.

3. A process as defined in claim 1 wherein said sheet includes a polymeric layer comprising acid capacity effective to lower the pH of said composition upon contact therebetween from a first pH to a second pH at which said visible image exhibits increased stability.

4. A process as defined in claim 3 wherein said spreader sheet further contains a spacer layer to time control the availability of said acid capacity to contact and thereby lower the pH of said processing composition, said polymeric layer being disposed between said sheet material and said spacer layer. I

5. A process as defined in claim 1 wherein said image is in silver.

6. A process for preparing a negative image comprising the steps of exposing a light-sensitive silver halide layer to form a developable image; applying an aqueous alkaline processing composition between said layer and a superposed transparent element to develop and fix said image; and thereafter reducing the pH of said image and said composition to a lower pH level substantially precluding image instability in the form of tiny transparencies in silver areas of said image while retaining said transparent element in superposition with said layer.

7.-ln a process for preparing a negative image comprising the steps of exposing a light-sensitive silver halide layer to form a developable image and developing said image by contacting said layer with an aqueous alkaline processing composition to form a developed and fixed negative image in said layer; the improvement which comprises applying said processing composition in a substantially uniform layer between said exposed silver halide layer and the coated side of a transparent sheet material bearing a layer of a reagent for reducing after said image formation the pH of said image and said composition to a lower pH level substantially precluding image instability in the form of tiny transparencies in silver areas of said image.

8. A process as defined in claim 7 wherein said processing composition includes a silver halide solvent system comprising a mixture of cysteine and a nitrogenous base.

9. A process as defined in claim 7 wherein said processing composition includes a silver halide developing system comprising a high-energy and a lowenergy silver halide developing agent, said low-energy developing agent being present in substantially greater concentration than said high-energy developing agent, the amount of each of said developing agents alone being insufficient to develop appreciable negative density, but said respective amounts together are capable of developing exposed silver halide to a desired usable density.

10. A process as defined in claim 7 wherein said reagent in said layer on said transparent sheet material comprises a polymeric acid.

11. In a process wherein an exposed silver halide layer containing a developable image is developed to form a fixed negative image by contacting said exposed dipropylamine,

layer with a viscous aqueous alkaline processing composition including a silver halide solvent system comprising the mixture of cysteine and a nitrogenous base and a silver halide developing system comprising a high-energy aminophenol silver halide developing agent and a low-energy silver halide developing agent selected from the group consisting of ascorbic acids and hydroxylamines, the low-energy developer being present in substantially greater concentration than the high-energy developing agent, the amount of each of said low-energy and high-energy developing agents alone being insufficient to develop appreciable negative density, but said respective amounts together are capable of developing exposed silver halide to a desired usable density;

the improvement which comprises developing said exposed silver halide layer by spreading said viscous processing composition in a substantially uniform layer between said silver halide layer and the coated side of a transparent sheet material having thereon a layer of a polymeric acid reactable with alkaline ions in said processing composition to reduce the pH in the environment of said negative image.

12. A process as defined in claim 11 wherein said nitrogenous base is a compound selected from the group consisting of ammonia, sec. amylamine, ethylamine, n-butylamine, allylamine, diethylamine, trimethylamine, triethanol amine, diethylene triamine, triethylene tetramine, N-hydroxyethyl propylene diamine, trimethylene diamine, ethylene diamine, aminoethyl ethanol amine, hydroxyethyl'diethylene triamine, tetraethylene pentamine, guanidine hydrochloride, piperidine, pyrrolidine,,2,5 dimethyl piperazine, polyethylene, imine, symmetrical dimethyl hydrazine and unsymmetrical dimethyl hydrazine; and said aminophenol contains in a position ortho to the phenolic hydroxyl group at least one substituent selected from the group consisting of amino, lower alkyl and lower alkoxy groups.

13. A process as defined in claim 11 wherein an inert alkaline ion-permeable polymeric layer is disposed over the outer surface of said polymeric acid layer.

14. A process as defined in claim 13 wherein said polymeric layer comprises a polyvinyl amide graft silver halide layer; a spreader sheet adapted to be placed in superposition with the side of said film unit containing said layer and which is employed to facilitate application of an aqueous alkaline processing composition between said film unit and said spreader sheet subsequent to exposure of said film unit in order to develop said film unit to form a visible image in said film unit; and a quantity of an aqueous alkaline processing composition adapted for spreading between said spreader sheet and said film unit;

the improvement wherein said spreader sheet contains, on the side of said sheet adapted for superposition with said film unit, a layer of a reagent for substantially lowering after substantial image formation the pH of said processing composition applied between said sheet and said film unit to develop said film unit and to form a visible image.

17. A product as defined in claim 16 wherein said support member is transparent.

18. A product as defined in claim 16 wherein said spreader sheet is transparent.

19. A product as defined in claim 16 wherein said spreader sheet further contains a spacer layer to time control the availability of said polymeric acid to contact and thereby lower the pH of said processing composition, said polymeric acid layer being disposed between said sheet material and said spacer layer.

20. A photographic product comprising, in combination, a photosensitive element comprising a light-sensitive silver halide layer contained on a transparent support member; a transparent element adapted for placement in superposition with said photosensitive element,

said transparent element comprising a transparent base member carrying a layer of a polymeric acid; and a quantity of a viscous processing reagent adapted for spreading in a substantially uniform layer between said respective elements when in superposition, said processing reagent comprising a viscous aqueous alkaline solution of a silver halide solvent system comprising the mixture of cysteine and a nitrogenous base and a silver halide developing system comprising a high-energy aminophenol silver halide developing agent and a low-energy silver halide developing agent selected from the group consisting of ascorbic acids and hydroxylamines, the low-energy developer being present in substantially greater concentration that the high-energy developing agent, the amount of each of said low-energy and high-energy developing agents along being insufficient to develop appreciable negative density, but said respective amounts together are capable of developing exposed silver halide to a desired usable density.

21. A product as defined in claim 20 wherein said nitrogenous base is a compound selected from the group consisting of ammonia, sec. amylamme,

ethylamine, n-butylamine, allylamine, diethylamine, dipropylamine, trimethylamide, triethanol amine, diethylene triamine, triethylene tetramine, N-hydroxyethyl propylene diamine, trimethylene diamine, ethylene diamine, aminoethyl ethanol amine, hydroxyethyl diethylene triamine, tetraethylene pentamine, guanidine hydrochloride, piperidine, pyrrolidine, 2,5- dimethyl piperazine, polyethylene imine, symmetrical dimethyl hydrazine and unsymmetrical dimethyl hydrazine.

22. A product as defined in claim 21 wherein said processing composition is confined in a frangible container.

Claims (21)

1. 2. A process as defined in claim 1 wherein said spreader sheet is transparent.
2. 3. A process as defined in claim 1 wherein said sheet includes a polymeric layer comprising acid capacity effective to lower the pH of said composition upon contact therebetween from a first pH to a second pH at which said visible image exhibits increased stability.
3. 4. A process as defined in claim 3 wherein said spreader sheet further contains a spacer layer to time control the availability of said acid capacity to contact and thereby lower the pH of said processing composition, said polymeric layer being disposed between said sheet material and said spacer layer.
4. 5. A process as defined in claim 1 wherein said image is in silver.
5. 6. A process for preparing a negative image comprising the steps of exposing a light-sensitive silver halide layer to form a developable image; applying an aqueous alkaline processing composition between said layer and a superposed transparent element to develop and fix said image; and thereafter reducing the pH of said image and said composition to a lower pH level substantIally precluding image instability in the form of tiny transparencies in silver areas of said image while retaining said transparent element in superposition with said layer.
6. 7. In a process for preparing a negative image comprising the steps of exposing a light-sensitive silver halide layer to form a developable image and developing said image by contacting said layer with an aqueous alkaline processing composition to form a developed and fixed negative image in said layer; the improvement which comprises applying said processing composition in a substantially uniform layer between said exposed silver halide layer and the coated side of a transparent sheet material bearing a layer of a reagent for reducing after said image formation the pH of said image and said composition to a lower pH level substantially precluding image instability in the form of tiny transparencies in silver areas of said image.
7. 8. A process as defined in claim 7 wherein said processing composition includes a silver halide solvent system comprising a mixture of cysteine and a nitrogenous base.
8. 9. A process as defined in claim 7 wherein said processing composition includes a silver halide developing system comprising a high-energy and a low-energy silver halide developing agent, said low-energy developing agent being present in substantially greater concentration than said high-energy developing agent, the amount of each of said developing agents alone being insufficient to develop appreciable negative density, but said respective amounts together are capable of developing exposed silver halide to a desired usable density.
9. 10. A process as defined in claim 7 wherein said reagent in said layer on said transparent sheet material comprises a polymeric acid.
10. 11. In a process wherein an exposed silver halide layer containing a developable image is developed to form a fixed negative image by contacting said exposed layer with a viscous aqueous alkaline processing composition including a silver halide solvent system comprising the mixture of cysteine and a nitrogenous base and a silver halide developing system comprising a high-energy aminophenol silver halide developing agent and a low-energy silver halide developing agent selected from the group consisting of ascorbic acids and hydroxylamines, the low-energy developer being present in substantially greater concentration than the high-energy developing agent, the amount of each of said low-energy and high-energy developing agents alone being insufficient to develop appreciable negative density, but said respective amounts together are capable of developing exposed silver halide to a desired usable density; the improvement which comprises developing said exposed silver halide layer by spreading said viscous processing composition in a substantially uniform layer between said silver halide layer and the coated side of a transparent sheet material having thereon a layer of a polymeric acid reactable with alkaline ions in said processing composition to reduce the pH in the environment of said negative image.
11. 12. A process as defined in claim 11 wherein said nitrogenous base is a compound selected from the group consisting of ammonia, sec. amylamine, ethylamine, n-butylamine, allylamine, diethylamine, dipropylamine, trimethylamine, triethanol amine, diethylene triamine, triethylene tetramine, N-hydroxyethyl propylene diamine, trimethylene diamine, ethylene diamine, aminoethyl ethanol amine, hydroxyethyl diethylene triamine, tetraethylene pentamine, guanidine hydrochloride, piperidine, pyrrolidine, 2,5-dimethyl piperazine, polyethylene, imine, symmetrical dimethyl hydrazine and unsymmetrical dimethyl hydrazine; and said aminophenol contains in a position ortho to the phenolic hydroxyl group at least one substituent selected from the group consisting of amino, lower alkyl and lower alkoxy groups.
12. 13. A process as defined in claim 11 wherein an inert alkaline ion-permeable polymeric layer is disposed over the outer surface of sAid polymeric acid layer.
13. 14. A process as defined in claim 13 wherein said polymeric layer comprises a polyvinyl amide graft copolymer.
14. 15. A process as defined in claim 11 wherein said polymeric acid is present in an amount sufficient to lower the pH in the environment of said negative image to below pH 8.
15. 16. In a photographic product comprising a film unit including a support member carrying a light-sensitive silver halide layer; a spreader sheet adapted to be placed in superposition with the side of said film unit containing said layer and which is employed to facilitate application of an aqueous alkaline processing composition between said film unit and said spreader sheet subsequent to exposure of said film unit in order to develop said film unit to form a visible image in said film unit; and a quantity of an aqueous alkaline processing composition adapted for spreading between said spreader sheet and said film unit; the improvement wherein said spreader sheet contains, on the side of said sheet adapted for superposition with said film unit, a layer of a reagent for substantially lowering after substantial image formation the pH of said processing composition applied between said sheet and said film unit to develop said film unit and to form a visible image.
16. 17. A product as defined in claim 16 wherein said support member is transparent.
17. 18. A product as defined in claim 16 wherein said spreader sheet is transparent.
18. 19. A product as defined in claim 16 wherein said spreader sheet further contains a spacer layer to time control the availability of said polymeric acid to contact and thereby lower the pH of said processing composition, said polymeric acid layer being disposed between said sheet material and said spacer layer.
19. 20. A photographic product comprising, in combination, a photosensitive element comprising a light-sensitive silver halide layer contained on a transparent support member; a transparent element adapted for placement in superposition with said photosensitive element, said transparent element comprising a transparent base member carrying a layer of a polymeric acid; and a quantity of a viscous processing reagent adapted for spreading in a substantially uniform layer between said respective elements when in superposition, said processing reagent comprising a viscous aqueous alkaline solution of a silver halide solvent system comprising the mixture of cysteine and a nitrogenous base and a silver halide developing system comprising a high-energy aminophenol silver halide developing agent and a low-energy silver halide developing agent selected from the group consisting of ascorbic acids and hydroxylamines, the low-energy developer being present in substantially greater concentration that the high-energy developing agent, the amount of each of said low-energy and high-energy developing agents along being insufficient to develop appreciable negative density, but said respective amounts together are capable of developing exposed silver halide to a desired usable density.
20. 21. A product as defined in claim 20 wherein said nitrogenous base is a compound selected from the group consisting of ammonia, sec. amylamine, ethylamine, n-butylamine, allylamine, diethylamine, dipropylamine, trimethylamide, triethanol amine, diethylene triamine, triethylene tetramine, N-hydroxyethyl propylene diamine, trimethylene diamine, ethylene diamine, aminoethyl ethanol amine, hydroxyethyl diethylene triamine, tetraethylene pentamine, guanidine hydrochloride, piperidine, pyrrolidine, 2,5-dimethyl piperazine, polyethylene imine, symmetrical dimethyl hydrazine and unsymmetrical dimethyl hydrazine.
21. 22. A product as defined in claim 21 wherein said processing composition is confined in a frangible container.