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Publication numberUS3260597 A
Publication typeGrant
Publication dateJul 12, 1966
Filing dateDec 2, 1960
Priority dateDec 2, 1960
Publication numberUS 3260597 A, US 3260597A, US-A-3260597, US3260597 A, US3260597A
InventorsSalminen Wilho M, Weyerts Walter J
Original AssigneeEastman Kodak Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Photographic multicolor diffusion transfer process using dye developers and development arrestors
US 3260597 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

y 1966 w. J. WEYERTS ETAL 3,260,597


This invention relates to the art of photography and more particularly to a multicolor diffusion transfer process in photography and materials adapted to use in the process.

A diffusion transfer color process has been described in a number of patents, including British Patent 804,971, published November 26, 1958, wherein photographic elements containing silver halide emulsion layers and layers containing diffusible dye developers (dyes having a silver halide developing function) are exposed to record the latent image in the silver halide and then treated with an alkaline processing composition which permeates the emulsion layers and layers containing the dye developers which then develop the latent images to silver images. At the same time oxidation products of the dye developers are formed in situ with the silver images and which are relatively non-diffusing in the colloid vehicle of the layers. The non-diffusing character of the oxidized dye developers is apparently due at least in part to a decrease in solubility in the alkaline processing liquid, and may also be due to a hardening effect of the oxidized developer upon the colloid vehicles of the layers which retards the diffusion of the oxidized dye developers. The residual unoxidized dye developers remaining in the layers in imagewise distribution are transferred by diffusion to a superposed reception element substantially to the exclusion of the silver image and oxidized dye developer to provide a positive dye image.

When an element containing differentially sensitized silver halide emulsion layers is used and subtractively colored dye developers are present in or contiguous to the respective emulsion layers, upon treatment with the processing liquid the dye developers are oxidized and rendered non-diffusing in the developed regions of the layers and the residual dye developer images in the positive regions are transferred by diffusion and in register to the reception element to provide a multicolor reproduction.

As is apparent, the success of the process depends in part upon the extent to which the dye developers in the exposed (negative) regions of the emulsion layers have been rendered substantially non-diffusing in the development reaction. Thus, if a quantity of unoxidized dye developer remains in a fully exposed negative region corresponding to the highlights of the subject, it will be transferred to the reception layer along with the unreacted dye developer in the positive regions and appears as high minimum density on the resultant color print. Typical dye developers such as 1,4-bis[p-(2,5-dihydroxyphenyl) ethylamino] -anthraquinone 3,Z9,597 Patented July 12, 1966 o nuomom H OH 0 NHCHaCH I on are relatively weak silver halide developing agents even when used at the comparatively high pH of the order of 13 required in the process and do not so rapidly develop silver halide emulsion as to take full advantage of known sensitometric properties of the emulsions and to obtain dye images having a full scale of density and contrast expected with other developing agents. As a result, color prints obtained in the processes may exhibit an undesirable high minimum density in the highlight regions, low color saturation, contrast and density and the color separation is poor. These effects are due in part to the inefficiency of the dye developers as silver halide developing agents, the lack of discrimination of the dye developers for the silver halide they should develop and other factors.

The above British patent, and other patents such as referred to hereinafter, relate to various features of the basic diffusion transfer color process using the dye developers, disclose how to carry out monochrome processes using the dye developers and that the monochrome principles of the particular invention are applicable to the multicolor reproduction. It has been discovered that when sensitive elements adapted to multicolor reproduction and containing a plurality of differently sensitized silver halide emulsion layers and contiguous dye developers for subtractive color reproduction are used in the process, the problems of the multicolor process and solutions thereof, are much dififerent from those of the monochrome process. For example, the development products of one emulsion tend to effect the development of the other emulsions, the diffusion of a dye developer from a lower layer can be affected i.e. be hindered, by a dye developer or other substance in an upper layer, the exhaustion of the processing solution by an outer layer may aifect development of a lower layer and one layer may not develop to the extent of another layer, and particularly one dye developer may not be immobilized sufficiently to prevent it from transferring and causing color contamination of a dye image of another color. Also, a given dye developer may develop some grains of silver halide in the wrong emulsion layer with the result than an insuflicient amount of that dye developer is available for transfer and the corresponding colors are unsaturated thus a magneta dye developer may develop some grains of red sensitive silver halide and become immobilized thus decreasing the magenta available to produce red colors which then appear unsaturated.

The above-mentioned losses in maximum density of the dye developer images may result from other causes. As

in other photographic processes, in the development of silver halide emulsions it is desirable to develop substantially only the exposed regions of the emulsions, however, unless precautions are taken development also proceeds to a certain extent in the unexposed regions resulting in the production of development fog. Compounds known as antifoggants are commonly used to suppress this fog, these compounds being used in the emulsions, developing solutions or both. In the above direct positive color transfer process using the dye developers, the formation of development fog in the unexposed regisions results in dye developers being immobilized which should not be, therefore, less dye developer is available for transfer to the receiving layer and the resulting images are lacking in density.

We have investigated the effect of using common antifoggants such as benzotriazole and 6-nitrobenzimidazole in the alkaline processing solution in order to prevent these losses in density due to the formation of fog. However, substantial overall fog accompanied by loss of density in the dye developer images is still obtained.

We have now discovered that if the development of the emulsions is arrested, not just suppressed, by means of development arrestors, at the time when development of the negative is substantially complete, the dye developer images have greatly increased maximum density. The latent images are thus allowed to develop very rapidly and the development arresting effect is delayed until the development of the exposed areas has essentially reached completion before development is appreciably arrested. This results in the prevention of development of the unexposed areas and the prevention of further development of the exposed areas. The development arrestors such as l-phenyl-5-mercaptotetrazole should not be confused with conventional development antifoggants such as 6- nitrobenzimidazole which retard the reduction of unexposed silver halide but allow the development of exposed silver halide to proceed. The development arrestors stop development of both exposed and unexposed silver halide and are most effective when an antifoggant is also present in the alkaline processing solution. This complete arrestment of development, particularly in the unexposed areas, results in a greater amount of dye developer being made available for transfer of the receiving layer, therefore, the greater overall maximum density is obtained in the prints. This complete arrestment of development is particularly important because the unexposed silver halide is easily reduced under the strongly alkaline conditions of the processing solution and this causes the dye developers in these unexposed regions to be made immobile and thus not available for transfer to the receiving layer. The development arrestors cannot be used in the alkaline processing solution in any appreciable amount or development will be stopped particularly in the outer blue and green sensitive emulsion layers. When the development arrestors are in the receiving layer and certain hydroquinone derivatives (below) are also present either in a layer of the sensitive element, in the solution or in a receiving layer, maximum density is increased and color contamination and minimum density are reduced. Furthermore, when the onium compounds (below) are used particularly together with the hydroquinone derivatives even further reductions in color contamination and minimum density and further increases in maximum density are obtained. Also, color drop-off decreases.

Color contamination usually appears in the prints as a degradation of one or more colors by one or more other colors and may be due to the failure of one or more dye developers to be immobilized sufficiently to prevent them from transferring from regions where they should have been immobilzed. Drop-off appears as a degradation in color quality of the prints apparently caused by one dye developer developing silver halide grains in the wrong emulsion layer, eg the magenta dye developer developing some red sensitive silver halide grains with the result that more magenta dye developer is immobilized than should be and the red colors are thus deficient in magenta and thus less saturated. The mentioned co-action between the development arrestors, antifog-gants, the onium compounds and the hydroquinone derivatives is particularly evident when the organic colloid vehicle of the sensitive element containing the dye developers, is composed principally of gelatin. Many of the common optical sensitizing dyes are conjugated quaternary ammonium salts but they are ordinarily not useful in place of the colorless onium compounds particularly because they are not suflicien tly soluble and diifusible and they impart undesirable stain to the prints.

One object of the invention is to provide photographic elements comprising several superposed differentially sensitized silver halide emulsion layers having contiguous dye developers and preferably hydroquinone derivatives, and to provide means for processing the elements including alkaline solutions, preferably containing antifoggants, for initiating development, and reception layers containing development arrestors, the onium compounds preferably being present. Sensitive elements, processing compositions and reception elements particularly adapted to the taking of pictures in a camera and the processing thereof in a camera will be provided.

The objects of the invention are accomplished in part by description hereinafter of representative sensitive elements comprising a plurality of silver halide emulsion layers differentially light-sensitive (sensitive to different regions of the spectrum), having contiguous dye developers which may be subtractively colored with respect to the sensitivity of the corresponding emulsion layer, and contiguous hydroquinone derivatives (preferably in a layer of the element), and by processing the exposed element by wetting with alkaline processing solution preferably containing an antifoggant in contact with the reception layer containing the development arrestor, preferably in contiguity with an onium compound diffusible in alkaline solution through the layers such as ternary sulfonium, quaternary phosphonium and especially quaternary ammonium compounds, to develop the exposed silver halide in the emulsion layers and thereby render the dye developers thereof non-diffusing in the regions of development, and the development arrestor to diffuse to the emulsion layers and stop further development, and allowing the dye developers in the undeveloped regions to transfer imagewise by diffusion and in register to the reception layer to yield a multicolor dye developer image thereon having increased density and decreased color contamination, color drop-01f and minimum density.

In the accompanying drawings are shown in greatly enlarged cross-sectional view the appearance of representative elements employed in a typical process of the invention.

In FIG. 1 of the drawings is shown in flow-sheet form a typical process embodying our invention according to which in stage 1 the sensitive element comprises a support 10, layers 11, 12 and 13 containing subtractively colored alkali-soluble cyan, magenta and yellow dye developers, the light-sensitive halide emulsion layers 14, 15 and 16 sensitive to red, green and blue light respectively, the interlayers 17 and 18 separating the green-sensitive emulsion and its contiguous subtractively colored magenta dye developer layer from the other layers and the overcoating layer 19 containing one of the hydroquinone compounds of the invention. The reception element containing support 20 and reception layer 21 containing a development arrestor (which may contain the onium salt) is positioned so as to receive dye images transferring by diffusion from the sensitive element, with a rupturable container of alkaline quaternary ammonium salt-silver halide solvent processing solution 22 which preferably contains an antifoggant therebetween. Upon rupture of the container 22 as by means of passing the. assembly between rollers in a camera so as to distribute he contents uniformly across a predetermined area of the sensitive element, the solution penetrates layer 19 dissolving the substantially water-insoluble alkali-soluble and dilfusible hydroquinone derivative and transporting it to the underlying layers Where the latent images in the silver halide of areas 23, 24 and 25 are developed to silver and the dye developers in the areas contiguous to areas 23, 24 and 25 each become immobilized and rendered non-difiusing. Thereafter, the unreacted dye developers of layers 11, 12 and 13 diffuse imagewise in register to the reception layer 21 and form the dye images thereon. The method of preparation of the described sensitive element and its use in the processes of the invention is described hereinafter.

In FIG. 2 of the drawings is shown an element in which the dye developers are incorporated into the differentially sensitized emulsion layers 31, 32 and 33, and the hydroquinone derivative is present in the layer 34 outermost from the support.

In FIG. 3 of the drawings is shown in schematic form, a light-impervious enclosure useful for processing an exposed roll of film containing silver halide emulsions and dye developers so as to wet the film with alkaline activator solution and bring it into contact with a mordanted reception sheet for transfer of a series of multicolor dye developer images to the sheet.

The development arrestors with which our invention is concerned are to be understood as including those compounds which are capable of diffusing in alkaline solution from a receiving 'layer to a contiguous silver halide emulsion layer undergoing development and thereby stopping development of exposed and unexposed silver halide, as opposed to antifoggants capable of only restraining development of silver halide emulsions.

The compounds which are effective as the development arrestors are either mercaptoazoles diffusible in alkaline solution and azoles which hydrolyze in alkaline solution to yield mercaptoazoles diffusible in alkaline solution; or iodides diffusible in alkaline solution and compounds releasing in alkaline solution iodides dilfusible in alkaline solution. The compounds increase the maximum density of the color prints Without substantially increasing minimum density.

The following are illustrative of the azole compounds:

S-myristoylthio-l-phenyl-1,2,3,4-tetrazole H N C- S 0 H20 H 0 C H: hydrolyzes to mercaptan) i C a O 5 5-,8-acetylethylthio-l-phenyl-1,2,3,4-tetrazole 2-mercapto-5-phenyl-1,3,4-oxadiazole 2-mercaptonaphth( 1,2) oxazole Z-mercaptobenzoxazole C-SH Z-mercaptobenzothiazole CSCH2C (C O 0 CH5): (hydrolyzes to mercaptan) 2- (2-dicarbethoxy )ethylmercaptobenzoxazole The iodide-containing or iodide-releasing compounds are illustrated by the following:

Potassium iodide.

(iodide-releasing) III-C Ha Benzothiazolium methiodide.

.HI Hgn (iodide-releasing) NH2 \N/ a bis-(Z-amino-S-iodopyridine hydroiodide)mercuric iodide.

It has been mentioned that the development arrestors are particularly effective when an onium compound is present with the result that increased density and decreased minimum density, color contamination and dropoff are obtained.

It is believed that the onium compounds interact with the dye developers to form salts thereof and that the improvements, particularly in density and highlights, are at least due in part to the effect of such salt formation on the solubility and diffusibility of the dye developers. There is evidence that the onium compounds actually temporarily delay the migration of the dye developers so that the initial difiusion rates of the dye developers are reduced, yet more of the dye developers transfer from less exposed areas to increase the density.

Onium compounds haae been used in the photographic art for quite some time. For example, U.S. Patent No. 2,648,604 discloses the use of non-surface-active quaternary ammonium compounds as development accelerators and US. Patents Nos. 2,271,623, 2,271,622 and 2,275,727 disclose the use of quaternary ammonium, quaternary phosphonium and tertiary sulfonium compounds as sensitizers for silver halide emulsions. Notwithstanding the fact that such onium compounds have been previously used as sensitizers and as development accelerators, the mentioned results obtained by using onium compounds in conjunction with the dye developers in the diffusiontransfer processes of this invention are worthy of note. In the processes disclosed in the above-mentioned US. patents, there is an increase in silver density in the negative due to the use of the onium compounds; however, the increase in density in such processes takes place in the exposed areas of the negative and is attributable to the above-mentioned ability of the onium compounds to sensitize an emulsion or to accelerate development. In the present processes, when an increase in density is obtained it takes place in the positive image and is primarily the result of increased transfer of the dye developer from unexposed areas of the negative. The fact that the onium compounds would coact with dye developers to increase the transfer of such dye developers from unexposed areas of the negative in no way was expected from the prior use made of such compounds as sensitizers or development accelerators. Further, the improvements in the present processes are not necessarily the result of improved surface activity due to the onium compounds because the onium compounds which usually bring about the greatest improvement in density would not be generally classified as surface active. It is believed that the increase in density is at least due in part to the ability of the onium compounds to increase the solubility of the dye developers.

The fact that the onium compounds would also act, especially in the presence of the hydroquinone derivatives, to inhibit transfer of the oxidized dye developers from the exposed areas and thus improve the highlights, -was similarly unexpected. This improvement in highlights is believed to be due to the ability of the onium compounds to control, especially in the exposed areas, the dilfusibility of such dye developers.

Especially useful results have been obtained through the use of quaternary ammonium compounds. As is known, quaternary ammonium compounds are organic compounds containing a pentavalent nitrogen atom. Generally, they can be considered as derivatives of ammonium compounds wherein the four valences usually occupied by the hydrogen atoms are occupied by organic radicals. Generally, the organic radicals are joined directly to .the pentava'lent nitrogen through a single or double carbon-to-nitrogen bond. The term quaternary ammonium, as used herein, .is intended to cover compounds wherein the pentavalent nitrogen is one of the nuclear atoms in a heterocyclic ring as well as those wherein each of the four valences is attached to separate organic radicals, e.g., tetraalkyl quaternary ammonium compounds. As illustrations of quaternary ammonium compounds, mention may be made of those represented by the following formulae:

wherein each R is an organic radical, Y is an anion, e.g., hydroxy, bromide, chloride, toluene sulfonate, etc., and Z represents the atoms necessary to complete a heterocyclic ring. As examples of compounds within Formulae 1, 2 and 3, mention may be made of tetraethylammonium bromide, N-ethylpyridinium bromide, N,N-diethylpiperdiniu bromide, ethylene-bis-pyridinium bromide, l-ethylpyridinium bromide, 1-phenethyl-3-picolinium bromide, tetra-alkylammonium salts, cetyltrimethylammonium bromide, polyalkylene oxide bis-quaternary ammonium salts such as polyethylene oxide bis-pyridinium perchlorate, the heterocyclic quaternary ammonium salts mentioned which form the methylene bases including 3-methyl-2- ethylisoquinolinium bromide, 3 methylisoquinolinium methyl p toluenesulfonate, 1 ethyl 2 methyl 3- phenethylbenzimidazolium bromide, 5,6-dichloro-l-ethyl- 2-methyl-3-(3-sulfobutyl)-benzimidazolium betaine and the pyridinium salts below.

The tertiary sulfonium and quaternary phosphonium compounds may be represented by the formulae:

wherein each R is an organic radical, e.g., alkyl, aralkyl, aryl, etc. groups, and X is an anion, e.g., hydroxy, bromide, chloride, toluene sulfonate, etc. As examples of tertiary sulfonium and quaternary phosphonium compounds, mention may be made of lauryldimethyl-sulfonium p-toluene-sulfonate, nonyl-dimethyl sulfonium ptoluene sulfonate and octyldimethylsulfonium p-toluene sulfonate, butyldimethylsulfonium bromide, triethylsulfonium bromide, tetraethylphosphonium bromide, dimethylsulfonium p-toluene sulfonate, dodecyldimethylsulfonium p-toluene sulfonate, decyldimethylsulfonium p-toluene sulfonate and ethylene-bis-oxymethyltriethylphosphonium bromide.

The onium compounds may be used as the hydroxide or as the salt. When the onium compounds are used as the salt, the anion may be a derivative of any acid. However, it should be noted that when the anion is iodide, such iodide may have deleterious efiects on the emulsion and suitable precautions should be taken. Especially good results were obtained when the onium compounds were employed as the bromide.

The particularly efiicacious heterocyclic quaternary ammonium compounds which form the methylene bases dilfusible in alkaline solution have the general formula wherein D represents the non-metallic atoms necessary to complete the heterocyclic nucleus of the quaternary ammonium compound containing 1 or more of the reactive methyl groups -CI-I R' in one or more of the nuclear positions, the other nuclear positions being substituted or not, such as quaternary salts of the pyridine, quinoline, benzoquinoline, benzoxazole, benzoselenazole, thn'azole, benzothiazole, naphthothiazole, benzimidazole, isoquinoline series, etc., n is 0 or 1, R is an alkyl group, an aryl or aralkyl group of the benzene series, or substituted alkyl, aryl or aralkyl groups of the benzene series, the alkyl chains preferably being lower alkyl of from 1 to 4 carbon atoms, R' is a hydrogen atom or one of the groups represented by R, and X represents OH- or an acid anion such as Br, CH SO or One or more of these quaternary ammonium compounds can be used alone or in combination with the onium compounds having the Formulae 1, 2, 3, 4 and 5 above, and are advantageously employed in either the processing solution, the reception element, or both, and less desirably in the light-sensitive element per se, to improve the print quality by a mechanism not fully understood. When the hydroquinone derivatives are also present a co-action with the quaternary compound takes place such that a greatly improved efl'ect is obtained distinguishable from the effect of either the hydroquinone derivative or the quaternary compound. The dye prints obtained exhibit appreciably less color contamination and improved color saturation, density and contrast.

The onium compounds can be used in varying amounts depending upon the particular compound and two or more can be used in combination. When used in the alkaline processing solution, useful results can be obtained with from about 0.2 to 15% of onium compound. In some cases about 0.2 to 3% is best. Similarly, the amount used in the sensitive element and receiving sheet will vary with the onium compound selected.

The quaternary ammonium compounds comprising a preferred embodiment of the invention are pyridinium salts which form the ditfusible methylene bases and which have the above Formula 6, the pyridinium nucleus being substituted with from 1 to 3 active methyl groups CH R' present in at least one of the 2, 4 or 6 positions, e.g. a

7 lower alkyl group such as methyl, ethyl, propylor substituted lower alkyl groups such as hydroxyalkyl, e.g. hydroxyethyl, which alkyl groups act as methylene base precursors. Positions 3 and may or may not be substituted with e.g. halogen, lower alkyl and haloalkyl groups such as chlorine, methyl, ethyl, propyl or chloroethyl groups.

Typical salts having the above Formula 6 are as follows:

l-benzyl-Z-picolinium bromide Br- CH3. Ni

I CsHaN pts Br Anhydro-1-(4-sulfobutyl) -2-picolinium hydroxide i CH2 drmsoh OH- a-picoline-fi-naphthoylmethylbromide i OHa- 1-18-phenylcarbamoyloxyethyl-Z-picolinium bromide (i12H4OCONHCoH 1-methyl-2-picolinium pts 1-phenethyl-2,4,6-trimethylpyridinium bromide l-phenethyl 4-n-propylpyridinium bromide 4- y-hydroxypropyl-l-phenethylpyridinium bromide, and l-n-heptyl-Z-picolinium bromide A number of pyridinium salts having the above general formula do not form methylene bases sutficiently diffusible in alkaline solution to be of practical use in the process e.g.

1-n-decyl-2-picolinium bromide 1,2-dibenzyl pyridinium bromide 6-amino-l-phenethyl-Z-picolinium bromide Z-amino-l-phenethyl-4-picolinium bromide Z-benzyl-l-phenethyl pyridinium bromide 4-benZy1-1phenethy1 pyridinium bromide The following which do not form methylene bases in alkali solutions are also less useful.

1Q l-phenethyl pyridinium bromide l-ethyl pyridinium bromide l-phenethyl-3-picolinium bromide l-n-nonylpyridinium pts The hydroquinones which have the requisite properties are substantially colorless, substantially water-insoluble, and soluble and difiusible in alkaline solution through organic colloid layers such as gelatin and are exemplified by the following Phenylhydro quinone 2-hydroxyphenylhydroquinone Phenoxyhydroquinone 4-methylphenylhydroquinone 1,4-dihydroxynaphthalene 2- (4-aminophenethyl) -5-bromohydroquinone 2- (4-aminophenethyl) -5-methylhydroquinone 4'-aminophenethylhydroquinone 2,S-dimethoxyhydroquinone 2,5-dibutoxyhydroquinone m-Xylohydroquinone Bromohydroquinone 3,6-dichlorohydroquinone 2-dimethylaminomethyltoluhydroquinone 2-cyclohexylhydroquinone Sec. 'butylhydroquinone 2,5-dichloro-hydroquinone 2,5-diisopropylhydroquinone 2,5-diiodohydroquinone 3-chlorotoluhydroquinone Tetrachlorohydroquinone 2,5-diphenylhydroquinone 2,5 -diresorcylhydroquinone 2,5-dioctylhydroquinone Dodecylhydroquinone The useful hydroquinone derivatives are particularly distinguished from the dye developers containing hydroquinonyl moieties mentioned hereinafter, in being substantially colorless and therefore do not impart any color to the print.

The processes of the invention are thus preferably carried out with the silver halide emulsions and dye developers in contiguity with the onium compounds and the hydroquinone derivatives a development arrestor being in the reception layer and an antifoggant preferably in the alkaline solution. The onium compound may be present in either or both the alkaline processing solution, in the reception sheet, less desirably in the sensitive element, and the hydroquinone derivative in any of the layers of sensitive element such as an overcoating layer, emulsion layer, dye developer layer, an interlayer or in a reception layer. For some purposes the hydroquinone derivatives may be present in the processing fluid; however, in the present invention this is less desirable since the hydroquinone derivatives are unstable in such solutions and readily undergo oxidation accompanied by discolorationof the prints.

The hydroquinone derivatives used as described, are preferably incorporated into emulsion layers, overcoating interlayers or other layers, as dispersions in the hydrophilic organic colloid vehicle of the layer. The hydroquinone derivatives may be dissolved in alkaline solution and precipitated into aqueous gelatin solutions by raising the acidity of the solution. However, this is a less desirable procedure because of the instability of the compounds in alkaline solution. The hydroquinone derivatives may be dissolved in a solvent, such as a lower alcohol, and precipitated into aqueous gelatin solutions for coating on the sensitive element. They may be added to gelatin solutions which are ball-milled to reduce the crystal size. However, the hydroquinones are preferably dissolved in a low molecular weight water-insoluble organic crystalloidal solvent permeable to the alkaline processing solutions and having a boiling point above about C. such as dibutyl phthalate and added to an aqueous gelatin solution which is passed through a colloid mil-l until the desired degree of subdivision has been attained. An auxiliary organic solvent can also be used such as one having a solubility in water greater than that of the crystalloidal solvent, of the order of at least about 2 parts per 100 parts of water. Thus the auxiliary organic solvent can be Washed from a chilled gelatin dispersion in the presence of the other solvent. The auxiliary solvent may be one having a boiling point at least about 25 C. lower than the crystalloidal solvent in order that it can be removed by volatilization during the drying of a coating to leave the hydroquinone derivative dispersed in only the crystalloidal solvent. As a result, the hydroquinone derivatives are quickly and uniformly dissolved by the alkaline processing composition and transported throughout the sensitive element to produce more uniform development than when the hydroquinone derivatives are incorporated into the element by other means.

The hydroquinone derivatives may be used in one or more layers of the sensitive element in quantities of the order of from about to 100 mgs. or more per square foot. However, the quantity used depends in part upon the amount of silver halide, the layer in which it is contained, the amount of dye developer and the amount of pyridinium salt in the sensitive element or processing solution of reception element. In some instances it may be desirable to form a complex of the hydroquinone derivatives by reaction with sulfur dioxide in a wellknown manner and to incorporate the complex in the overcoating layer, outer emulsion or other layer of th sensitive element. These complexes tend to be moi stable than the hydroquinone derivatives themselves.

The dye developers which are used in the emulsion layers or in layers adjacent to the emulsion layers are compounds which are both a silver halide developing agent and a dye. They are characterized by being relatively non-diffusible in the colloid layers at a neutral pH but ditfusible in the layers in the presence of the alkaline processing solutions. For the most part the dye developers are insoluble in water per se, which property usually necessitates the use of organic solvents to incorporate the dye developers into the organic colloid layers of the sensitive elements. Otherwise, the solubility of the dye developers is not particularly important and so long as the dye developers are capable of being immobilized in the layers in the presence of the alkaline processing solution and they are transferrable to the reception element, they are useful in the process of the inven tion. The dye developers are particularly characterized by containing both a chromophore moiety and at least one moiety such as a hydroquinonyl radical having a silver halide developing agent function and which radical imparts silver halide development activity to the dye developer molecule as a whole with the result that during development of a silver halide image, the dye developers are oxidized to less difiusible compounds in the region of exposure and development and the residual dye developers in the undeveloped regions are transported imagewise to mordanted reception layers to provide a dye image thereon. The dye developers of course should not have a desensitizing action toward silver halide emulsions.

Representative dye developers of use in the sensitive elements of the invention have the general formula in which M is an aromatic or heterocyclic ring or ring system such as a benzene, naphthalene, tetralin, anthracene, anthraquinone, pyraz'ole, qu-inoliue, etc., ring and may also be substituted, as by hydroxyl amino, keto, nitro, alkoxy, aryloxy, acyl, alkylamido, arylamido, alkyl, aryl, carboxamido, sulfonamido, carboxyl or sul-fo groups. D represents a silver halide developing agent moiety imparting the developing agent function to the dye developer such as a hydroquinolyl group which may be substituted with amino, alkylamino, alkyl, hydroxyl, alkoxyl or halogen groups.

A very useful type of dye developers disclosed in Australian Patent 220,279 accepted December 17, 1958 and German Patent 1,036,640, August 14, 1958 have the general formula open chain reaction methylene coupler containing the group -CO-CH CO--, for example:

4- [p-( 2',5 -dihydroxyphenyl) -phenylazo] -5-acetamido- 1-n aphthol.

4- [p-( 2',5 -dihydroxyphenethyl) -phenylazo] -5-benzamido- 1 -naphthol.

1-phenyl-3 -methyl-4- [p-(2',5 '-dihydroxyphenethyl) phenylazo] -5-pyrazolone.

2- [p- 2, -dihydroxyphenethyl) -phenylazo] -4- acetamidol-naphthol.

2- [p- 2, 5 dihydroxyphenethyl) -phenylazo] -4- aminol-naphthol.

(|)H O H CHa-OH2N=N (magenta dye developer) I O H O C H3 2- [p- (2',5 '-dihydroxyphenethyl) -phenylazo] -4- methoxy-l-naphthol.

2- [p- (2',5 'dihydroxyphenethyl -phenylazo] -4- ethoxyd-naphthol.

2- [p- (2', '-dihydroxyphenethy1) -phenylazo] -4- n-propoxyl-naphthol (Compound 11) l-phenyl-3-N-n-butyl-carboxamido-4-[p- 2',5-dihydroxyphenethyl) -phenylazo] -5 -pyrazolone.

1-phenyl-3-N-n-hexylcarb ox amido-4- p-'( 2',5 '-dihydroxyphenethyl) phenylazo] -5-pyrazolone (Compound IH) l 1-phenyl-3-carbethoxy-4- [p-=(2,5 '-dihydroxyphenethyl) phenylazo] -5-pyrazolone.

2- [p 2',5 -dihydroxyphenethyl) phenylazo] -4-isopropoxyl -naphthol.

1-phenyl-3-N-cyclohexyloarb ox amido-4- [p- 2',5 '-dihydroxyphenethyl) phenylazo] -5-pyrazolone.

1-phenyl-3-phenyl-4- [p-( 2',5 -dihydroxyphenethyl) phenylazo] -5 -pyrazolone.

2-(4- [p- (2",5 "-dihydroxyphenethyl) -phenylazo] -0tnaphthylazo-4-methoxy)-1-naphtho1.

1-phenyl-3-amino-4- (4'- [p-(2,5-dihydroxyphenethyl) -phenylazo] -2',5 '-diethoxyphenylazo pyrazolone.

1-acetoxy-2- [p-(B-hydroquinonylethyl) -phenylazo] -4- methoxy naphthalene.

4-isobutoxy-2- [p- (B-hydroquinonylethyl) -phenylazo] l-naphthcl.

l-acetoxy-Z- [p-(ti-hydroquinonylethyl) -phenylazo] -4- propoxy naphthalene.

2- [p- 2',5 -dihydroxy-4'-methylphenethyl) phenylazo] 4-propoxyl -naphthol.

1-phenyl-3- [N-( B-ethylhexyl) -carboxamido] -4- [p-(fl-hydroquinonylethyl) -phenylazo] -5-pyrazolone.

1-phenyl-3( N-n-heptyl) carboxamido-4-[p- (ti-hydroquinonylethyl) -phenylazo] -5-pyrazolone.

l- (o-carboxyphenyl -3-phenyl-4- [p-(2,5-trifluoro acetoxy-fl-phenylethyl) phenylazo] -5-hydroxy pyrazole lactone.

lo-carboxyphenyl) -3-N-phenylcarb oxarnido-4- [p-(BC hydroquinonylethyl) -phenylazo] -5-hydroxy pyrazole lactone.

I Another class of dye developers disclosed by British Patent 804,971, November 26, 1958, and British Patent 804,973, November 26, 1958 have the general formula group, which may be aliphatic, e.g., acetyl or aromatic, 'e.g. benzoyl, Z is a bivalent organic radical containing at least one methylene (CH group, m is a positive integer less than 5 and each Y may be a hydrogen or halogen atom or an amino, alkyl, aryl, nitro, alkylamino, arylamino, aryloxy, alkoxy, hydroxyl, sulphonamido,

carboxamido, carboxy, sulpho,

' Examples of these dye developers are 1,4-bis-( 2',5'-dihydroxyani1ino -anthraquinone, 1,5 -bis(2,5 -dih'ydroxyanilino -4,8-dihydroxyanth'raquinone,

1,4-bis ,8-( 3 ',4'-dihydroxyphenyl ethylamino] anthraquinone,

OH CH3 I I O lfHCH-CHzl l I (cyan dye developer) 0 H NH? H-CH CH:

1,4-bis [,B- (2',5-dihydroxyphenyl) -isopropylamino] anthraquinone,

. 1,4-bis ,8- (2',5 '-dihydroxyphenyl -ethylamino] anthraquinone,

1-chloro-4-[B-(2',5'-dihydroxyphenyl)ethylamino] anthraquinone, N-monobenzoyl-lA-bis-[fi-(3',4'-dihydroxyphenyl) ethylamino] -anthraquinone, N-monobenzoyl-l,4-bis[B-(2',5'-dihydroxyphenyl)- ethylamino] -anthraquinone, 5,8-dihydroxy-1,4-bis[(p-hydroquinonyl-a-methyl) ethylamino]-anthraquinone (Compound I) 1,4-bis 8-hydroquinonyl-a-ethyl) ethylamino] anthraquinone,

5 -hydroxy-1 ,4-bis fi-hydroquinonyl-a-methyl) ethylamino] -anthraquinone,

1- B-hydroxy-w-ethyl-ethyl amino -4- a-hydroquinonyla-methy lethyl-amino-anthraquinone and 1-(butanol-2'-amino)-5,8-dihydroxy-4-hydroquinonylisopropyl-amino-anthraquinone.

In the formulas above the expression bivalent organic radical Z refers to organic radicals having the two free valences attached to different atoms. As examples of such suitable bivalent organic radicals, mention may be made of alkylene radicals such as (I311: -CHg, -C H2-CHz, O HZ CH as well as bivalent radicals such as It is also intended that Z may be saturated, unsaturated, such as CH CH=CH-CH or substituted, such as chloroalkylene or hydroxyalkylene.

Where Z is an alkylene group, best results are obtained by the use of a lower alkylene group, e.g. an alkylene group, containing less than about six carbons, and preferably an ethylene (CH CH group. Alkylene groups containing more carbon atoms may be used, however, providing that the resulting dye developer is capable of being dissolved in the liquid processing composition described herein, and its oxidation product rendered im mobile in the developed emulsion layer.

Acylation of amino-nitrogen atoms which are part of the chro-mophoric system has the effect of shifting the visible absorption band of the compound toward higher frequencies (shorter wave-lengths). Thus, acylating one amino-nitrogen of the cyan, 1,4-bis-[[3-(2',5'-dihydroxyphenyl)ethylamino]-anthraquinone changes its color to a magenta, and acylating both the amino-nitrogen atoms changes its color to an orange-yellow. Similarly the acylation of hydroxyl groups of the above types of dye developers can be expected to shift the color of the dye developers. Thus, the dye developers may undergo a change in structure and/or color during the development reaction, for example through hydrolysis, and the dye which is transferred may have a color different than that of the dye developer originally present in the sensitive element.

Additional dye developers are disclosed in Belgium Patent 554,935, British Patents 804,971, 804,973-5 and French Patent No. 1,168,292.

The following dye developers are also useful in the sensitive elements and processes of the invention:

Cyanurated dye developers such as 2-hydroquinoneamino-4- (p-phenylazo)anilino-6-hydroxy-4-triazine (Canadian Patent No. 579,038).

Anthraquinone dye developers such as 1,4-bis(2',5'- dihydroxyanilino)-a11thraquinone and 1,4-diamino-N- (/3- 2,5 dihydroxyphenyl-a-methyl-ethyl) -2,3 -anthraquinonedicarboximide.

Amino substituted tanthraquinoue dye developers such as prepared by reaction of 1-amino-4-(p-aminoanilino)- anthraquinone-Z-sodium sulfonate with chloroacetamido hydroquinone mon'obenzoate.

Dye developers obtained by reaction of 1-phenyl-3- amino-4-phenylazo-5-pyrazolone or 1,4-bis-(18-aminoethylamino) -anth raquinone with h'omogentisic acid lactone or acid chloride, or gentisic acid chloride e.g. 1-phenyl-3-(2',

'-dihydroxyphenyl-acetamido -4-phenylazo-5-pyr azolone' (Blout et a1. Canadian Patent 577,021 dated June 2, 1959).

Naphthamide dye developer such as 1-(2,5-dimethoxyphenyl-azo 2-hydroxy N (2',5'-dihydroxypheny-l)-3- naghthamide (French Patent 1,168,292 dated August 25, 19 8).

Disazo dye developers such as 2-[p-(1-hydroxy-3,6- disulfo-8-amino-2-naphthylazo)-3,3'-dimethoxybisphenyleneazo]-hydroquinone and 2-(2',5'-dimethoxy-4'[p-(2", 5" dihydroxyphenethyl) phenylazo] phenylazo)-l,8- naphthalene diol-3,6-disulfonic acid.

Arylazonaphthol dye developers, e.g. 1-a-min0-4-phenylazo-2-naphthol.

Anthrapyridone dye developers e.g. l-acetyl-3-fl-(2', 5'-dihydroxyphenyl)-ethyl-6-fl-(2',5 dihydroxyphenyl)- ethylaminoanthrapyridone.

Thiohydroquinoyl dye developers, e.g. l-phenyl-3- methyl 4 [p (2',5 dihydroxyphenylthioethyl)- phenylazo]-5-pyrazolone (Belgian Patent 568,344).

Ortho coupled dye developers exhibiting limited sensitivity to changes of pH e.g. 2-(p-[2",5"-dihydroxyphenoxy]phenylazo)-4-methoxy-1-naphthol and 1-phenyl-3- methyl-4-[p-hydroquinolylsulfonyl)-phenylazo-] S-pyrazolone.

Oxalyl ester dye developers, e.g. 1-phenyl-3-amino-4 [p-(2,5'-bis-ethoxalyloxyphenethyl) phenylazo] 5-pyrazolone.

Leuco compounds may be used similarly e.g. l-phenyl- 3-methyl 4-(2'-methyl-4'-diethylamino)anilino-S-pyrazolone, which do not exert a filtering action on underlying emulsion layers and which are immobilized in the developed regions, difiuse imagewise from undeveloped areas to the reception layer and are oxidized to colored images therein.

The dye developers may be incorporated into the emulsion layers or into the layers thereunder by several methods. For example, the dye developers may be dissolved in organic solvents and precipitated into gelatin solution or the dye developers may be ball-milled in gelatin solutions to reduce their particle size. However, particularly favorable results are obtained when the hydroquinone derivatives of the invention are present in one or more of the layers of the sensitive element and the dye developers have been incorporated into the gelatin layers under the emulsion layers (as shown in FIG. 1) by dissolving the dye developers in high boiling solvents such as ditetrahydrofurfuryl adipate or 2-(2-butoxyethoxy)ethyl acetate and milling the mixture in gelatin solution in a colloid mill. When high boiling solvents having low solvent activity for the dye developers, such as dibutyl phthalate, are used it is desirable to dissolve the dye developer in a mixture of the high boiling solvent and a low boiling solvent such as cyclohexanone, methanol, etc., which evaporates readily from the coatings during the subsequent drying operation. Many of the dye developers can be used with the high boiling solvents (in absence of low boiling solvents) such as the following:

Ditetrahydrofurfuryl phthalate B-methoxyethyl phthalate Ethyl N,N-di-n-butylcarbamate Guaiacol acetate (o-methoxyphenyl acetate) Tetrahydrofurfuryl propionate Triethyl citrate Acetyl triethyl citrate Tricresyl phosphate Tri-p-tert.butylphenyl phosphate Triethylphosphate Tri-n butylphosphate Triphenylphosphate 1.6 Isoamyl acetate Ditetrahydrofurfuryl succinate Methyl acetate Ditetrahydrofurfuryl adipate Tetrahydrofurfuryl benzoate N-n-amylphthalimide Ethyl N,N-di-n-butylcarbamate Diethyl lauramide Dibuytl lauramide Lauroyl piperidine N-n-butyl acetanilide Tetraethyl phthalamide N-n-amyl succinirnide 4-methyl-2-pentanol 2,4-di-n-amylphenol Ethylene glycol monobenzyl ether Methyl isobutyl carbinol Furfuryl alcohol Cyclohexanone 2-(2-butoxyethoxy)ethyl acetate The isomeric 2-, 3- and 4-methylcyclohexanones are particularly useful lower-boiling solvents for use with the above high-boiling solvents for dispersion of dye developers such as the cyan dye developers l,4-bis-(-2,5-dihydroxyphenylisopropylamino)-anthraquinone, 5,8-bis [B- hydroquinoyl-a-methyl)ethylamino]quinizarin and 1,4- bis(2,5-dihydroxyphenylisopropylamino) 5 hydroxyanthraquinone, and the magenta dye developer 4-meth- 0xy-2-[p-(,B-hydroquinoylethyl) phenylazo]-1-naphthol. As a result the gelatin solutions containing dispersions of dye developers produce stable dried coatings in which the dye developers do not tend to crystallize out.

The dye developers are employed in the sensitive elements contiguous to the silver halide of the emulsion layers, that is, they may be present in one or more of the emulsion layers or preferably in a hydrophilic organic colloid layer immediately next to and particularly under the silver halide emulsion layer. Especially good results are obtained when the dye developers are positioned so as to be present in the layer immediately under the emulsion layer, the sensitivity of which iscomplementary to the color of the dye developer as shown in FIG. 1 of the drawings. It appears less desirable to locate the dye developer in a layer positioned above the corresponding layer of silver halide emulsion. The contiguity of the dye developer with respect to the silver halide can take the form of a mixed packet system wherein the dye developer may be present in a matrix surrounding a particle or globule containing silver halide grams.

In multilayer sensitive elements of the type shown in FIG. 1 the order of arrangement of the dilferentially sensitized silver halide emulsion layers on the support can be diflerent, e.g. reversed so as to have the bluesensitive emulsion layer on the support and. the redsensit-ive emulsion layer outermost. In such arrangements of layers the sensitivities of the silver halide emulsions should be adjusted so as to prevent recording unwanted blue light images in the emulsions primarily sensitive to the red and green regions of' the spectrum, e.g. a silver bromide emulsion can be used for the blue sensitive emulsion and silver chloride emulsions for the other layers. In instances of this type it may be desirable to utilize the leuco compounds mentioned above in place of one or more of the dye-developers which, since they may have some blue absorption, might tend to exert an undue filtering action on the blue-sensitive, bottom emulsion layer.

The hydrophilic organic colloid vehicle of the emulsion layers, overcoating layers, of the dye developer layers and of interlayers can be varied somewhat, for example, gelatin, gelatin derivatives such as dibasic acid esters of gelatin, polyvinyl alcohol and cellulose acetate hydrogen phthalate or mixtures of these may be used. However, the best and most consistent results, and conshould be at least about 75% of the measured thickness of the yellow dye developer layer and contain at least about two times the amount of gelatin present in that layer in order to prevent undue wandering of the dye development products from layer to layer. Other hydrophilic organic colloids yield less desirable results when used in the layers. For example, when some of the layers contain gelatin vehicle and 'interlayers of polyvinyl alcohol or cellulose acetate hydrogen phthalate are used, the layers tend to strip apart particularly when dry. Also, when gelatin is used throughout more uniform transfer of the alkaline processing solution and hydroquinone derivative through the layers is obtained and the dye developers comprising the final print transfer more readily to the reception layer.

The processing solution used to initiate development of the exposed sensitive elements containing the dye developers and hydroquinone derivatives, and which may contain the quaternary ammonium salt, should be strongly alkaline to accelerate the development activity of the dye developer as much as possible. Alkali metal hydroxides such as sodium hydroxide or alkaline salts such as sodium carbonate are advantageously used in the activator composition for this purpose. However, quaternary ammonium hydroxides or volatile amines such as diethyl amine, which have the advantage of being volatilized from the prints and therefore leave no residue of alkali thereon which might tend to decompose the dye images, may also be used. As mentioned previously, since the hydroquinone derivatives may tend to be unstable in the strongly alkaline activator, they are preferably not incorporated in the processing solution although when the pyridinium salts are present, results are obtained which are satisfactory in other respects. The results most desired are obtained when the hydroquinone derivative is present in the layers of the sensitive elements. Therefore, no silver halide developing agent need be present in the processing solution.

The sensitive elements of the invention are of course adapted to use in a camera for taking pictures in the usual manner. Moreover, the development of the sensitive elements, i.e. the treatment with an alkaline activator solution to initiate development, can also be carried out in the camera by use of rupturable containers of processing solution used as illustrated in FIG. 1 of the drawings or other means may be used to spread the processing solution uniformly across the picture area of one or more consecutively exposed images and in contact with the reception layer. For this purpose, it may be desirable to use a processing solution containing in addition to strong alkali a thickening agent such as carboxymethyl cellulose or high-viscosity hydroxyethyl cellulose in suitable quantity to obtain the desired viscosity. Other means can be used such as spraying, dipping, roller coating, etc. to apply to the processing solution to the exposed element and to initiate its development. The alkaline processing solution may be replaced with Water or a water solution of pH 7.5 or less if the contiguous receiving sheet contains an alkali or an alkali releasing material. If the water or water solution is integumented and incorporated in the light sensitive element or in the mordanted receiving sheet it may be released by suitable mean such as by pressure or by heat.

Thus, several consecutive exposures on a strip of the sensitive element can all be wetted with the alkaline processing solution and the dye developer images transferred to a single strip of reception material to provide several color prints in a single transfer operation.

One method for obtaining the color prints from a strip of the sensitive element containing a series of, for example, three or four consecutive exposures, is to apply a viscous processing solution from a releasably confining or rupturable container in a compartment such as a magazine, integral with a camera in the manner described below, to cause each of the exposed areas to be wetted with the processing composition at approximately the same time in cont-act with a strip of reception material and the corresponding multicolor images to transfer thereto to provide a series of colored images on a single strip of the reception material.

A different means for providing prints from the sensitive element containing a series of image exposures such as three or four consecutive exposures, is to expose the element to several subjects in a conventional camera not necessarily adapted to use of rupturable containers of the processing composition, and withdrawing the exposed element from the camera in a convenient manner so as to prevent fogging of the emulsions. Thus, the element can be exposed and wound upon itself on a spool in an ordinary roll-film type of camera so as to exclude light, by use of a light-impervious covering such as black paper, a cassette or a magazine. The element can then be withdrawn from the camera and placed in a convenient portable light-impervious enclosure of small dimension such as shown in FIG. 3, for application of the processing fluid to the element from, for example, a single rupturable container or several rupturable containers corresponding to the number of exposures recorded on the strip of sensitive element, or by application of the viscous or non-viscous fluid to the element by means of a Wick, roller or similar applicator, so that each of the exposed areas is wetted. As a result, the element comprising several image exposures on a single strip of differentially light-sensitive emulsion layers and subtractively colored dye developers contiguous to the silver halide of each emulsion layer, is wetted with the alkaline fluid in the presence of the cationic onium salts, and in the presence of the hydroquinone derivatives, and brought into contact with the reception layer for a time sufficient for adequate development of each image, to cause the silver halide in the several exposed areas of each emulsion layer to develop and thereby render the corresponding dye developers immobile and the dye developers in the unexposed portions of each of the several exposed areas to transfer to the reception layer and provide a series of prints thereon composed of the dye developers. In FIG. 3 is shown a schematic representation of an apparatus useful for this purpose and the process for making the series of prints from a sensitive element containing a series of exposures. The film 40 wound emulsion side inwards, having the structure shown in FIG. 1, Stage 1 and comprising a support having superposed thereon differentially sensitized emulsions and contiguous dye developers, which has been exposed so as to record a series of multicolor subjects, is quickly passed between rollers 41 and 42 so as to pick up the alkaline activator solution 43, such as Activator II, contained in pan 44, which is supplied by roller 42 dipping into the solution. Thence the film continues between rollers 45 and 46 where it is brought into contact with the mordanted receiving sheet 47, such as Receiving Sheet A, to form the sandwich 48. The exposed silver halide in each emulsion layer then develops, corresponding dye developers become immobilized and the unreacted dye developers then transfer to sheet 47, after which the sandwich passes out of the enclosure and is stripped apart to provide a series of positive dye developer images on sheet 47 at 50.

Camera apparatus of the type useful for exposing and processing the sensitive elements of the invention have been described, for example, in US. Patent 2,435,717. Such cameras permit successive exposure of individual frames of the photosensitive element from the emulsion side as Well as processing of an exposed frame by bringing the exposed portion of the photosensitive element in superposed relation with a portion of the print receiving element while drawing these portions of the film assembly between a pair of pressure rollers which rupture the container associated therewith and spread the processing liquid between and in contact with the photosensitive element and the corresponding registered area of the print receiving element. The photosensitive element and print receiving element during the spreading of the container contents become formed into a combination wherein the photosensitive element and print receiving element are so superposed with respect to each other that the spread liquid has access to both of the elements. This superposed relationship between the photosensitive and print receiving elements is maintained until the elements are stripped apart following the deposit on the print receiving element of the dye forming the final color image.

The reception layers containing the development arrestors may be composed of various materials such as linear polyamides, proteins such as gleatin, polyvinyl pyrrolidones, poly-4-vinyl pyridine, polyvinyl acetate, polyvinyl alcohol, cellulose acetate, polyvinyl salicylal, partially hydrolyzed polyvinyl acetate, methyl cellulose, regenerated cellulose, carboxym'ethyl cellulose and hydroxyethyl cellulose, and mixtures thereof.

As will be apparent from a consideration of other color processes using dyes, the prints composed of the dye developers undergo decomposition to some extent when exposed to heat, light and moisture. Accordingly, it is advantageous to treat the prints to reduce these effects as much as possible. For this purpose solutions of a number of materials can be swabbed on, sprayed on or otherwise applied to the prints to improve the stability of the dye images such as solutions of tannic acid, a condensation product of naphthalene sulfonic acid and formaldehyde, and polyvinyl pyrrolidinone. An exceptionally useful synergistic composition is a solution of polyvinyl alcohol containing a saccharide such as mannitol, levulose, arabinose, maltose, mannose, etc., neither the polyvinyl alcohol nor the saccharide being effective per se to stabilize the dye developer images.

It may be desirable to use a silver halide solvent in the process. The use of silver halide solvent is not to be confused with the use of silver halide solvent in the Wellknown silver halide diffusion transfer processes, since in the present processes such small amounts of silver halide solvent are used that virtually no silver halide is transferred to the receiving sheet during the transfer of the dye developed images. The presence of the silver halide solvent appears to alter the characteristics of the activator in that there apparently occurs a catalyst reduction of the latent image centers of the exposed areas of the negative element. The activator solutions which appear to have some solvent action on the silver halide tend, especially in the presence of the onium compound, to produce more effective development of the exposed silver halide grains. Also, the desired results are not obtained by use of silver halide solvent alone, in absence of either the onium compound or the hydroquinone derivative. Useful results are obtained using from about 0.5 to 2 percent by Weight of silver halide solvent in the alkaline processing solution. The amount used in the receiving sheet will vary depending in part upon the rate of diffusion of the silver halide solvent from the sheet into the alkaline processing solution. Silver halide solvents are those commonly used in the art and having no deleterious efi'ect on the process and include sodium, potassium and ammonium thiosulfates and thiocyanates. The silver halide solvent can be present in the alkaline processing solution or in the receiving sheet, the hydroquinone derivative for most purposes being present in the sensitive element and less desirably in the alkaline processing solution and the receiving sheet, and the onium compound being present in the alkaline processing solution or the receiving sheet or both but less desirably in the sensitive element. When both the silver halide solvent and the hydroquinone derivatives are present, a substantial decrease in color contamination and minimum density of the prints is observed. When the silver halide solvent and the onium compounds are present, a similar decrease in color contamination and minimum density is obtained as well as an appreciable decrease in color drop-01f especially when the silver halide solvent, the hydroquinone derivative and the onium compound are all present. In addition, a substantial improvement in effective speed of the sensitive element is obtained which may have been produced by (1) a latensifying action of the silver halide solvent-containing activator resulting in increased developer activity producing development of grains which may have received somewhat too little exposure to develop in normal activators or by (2) physical development or intensification occurring simultaneously with normal development.

The invention contemplates sensitive elements wherein the emulsion layers, contiguous hydroquinone derivatives and dye developer layers are integral with the support e.g. coated on a support capable of receiving the dye developed images and containing one of the development arrestors, the support being of a nature such that it can be stripped away from the sensitive layers or a stripping layer may be provided between the reception layer and the other layers to facilitate the stripping operation. The alkaline fluid can thus be supplied as described above or in case the alkali is contained in one of the layers and fluid may merely be water supplied to release the alkali.

The silver halide emulsions of the sensitive elements of the invention include well-known silver halides and mixtures thereof, for example, silver bromide, silver bromoiodide or silver chlorobrimide emulsions.

The following examples will serve to illustrate the invention.

EXAMPLE l.USE OF DEVELOPMENT ARRESTOR IN RECEIVING SHEET AND ALKALINE ACTI- VATOR SOLUTION A sensitive element having the structure shown in Stage 1 of FIG. 1 was prepared by coating a subbed film support 10 with suitable hardened gelatin layers as follows:

Layer 11 An aqueous gelatin solution containing the cyan dye developer (Compound I above) dissolved in a mixture of N-n-butylacetanilide, 4-methy1 cyclohexanone and dispersing agent Alkanol B, and the mixture passed through a colloid mill several times, coated and dried so as to volatilize the 4-methyl cyclohexanone.

Layers 14, 15 and 16 Gelatino silver bromoiodide emulsion layers sensitized, respectively, to the red, green and blue regions of the spectrum.

Layers 17 and 18 Gelatin interlayers.

Layer 12 An aqueous gelatin solution containing the magenta dye developer (Compound II above) dissolved in a mixture of cyclohexanone, N-n-butylacetanilide and Alkanol B, and the mixture passedthrough a colloid mill several times, coated and dried to volatilize the cyclohexanone.

Layer 13 An aqueous gelatin solution containing the yellow dye developer (Compound III above) dissolved in a mixture of ditetrahydrofurfuryl adipate, ethylene glycol monobenzyl ether, and Alkanol B, and the mixture passed through a colloid mill several times, the resulting dispersion chilled to set it, washed to remove ethylene glycol rinonobenzyl ether followed by coating upon layer 18 and rymg.

Alkanol B aqueous solution) ml 2 136 1 Heat at 70 C. to dissolve then 0001 to 40 C. 2 Heat to 40 C.

Part A was slowly added to Part B with the aid of mechanical agitation. The solution obtained was then passed through a Manton-Gaulin laboratory colloid mill five times. The colloid mill was then rinsed and the dispersion was adjusted to a weight of 3775 g., chill set and stored in a refrigerator.

The coating composition for layer 19 was prepared as follows:

Part I:

Dispersion D-1 g 1 3775 Water ml 1 2225 Part II:

% gelatin solution g 3180 Water ml 2 12,000 Mucochloric acid (2.7% aqueous solution) ml 2 515 1 Heat to 40 C. 2 Heat to 40 (3., adjust pH to 5.5.

Parts I and II were then combined and diluted with water to 22,700 ml. This solution was coated as layer 19 of FIG. I to yield a coverage of approximately 120 mg. of gelatin per sq. ft. and 40 mg. per sq. ft. of 4-methylphenylhydroquinone identified hereinafter as MPHQ.

Samples of the resultant film each designated as 756 were exposed under a step table through red, green and blue filters and each wetted with the Activators II, IX, X and XI (described below) in contact with Receiving Sheets A or C (below). After about two minutes the receiving sheets were removed and the D and D values of the prints were recorded using red, green and blue filters in the usual manner. These data are tabulated in Table I below as Tests 1-6. By comparing Tests 1 and 2 it can be seen that when the development arrestor Compound IX (cpd IX) was in the receiving sheet appreciably higher D was obtained. Also, the addition of IX to the activator (Tests 5 and 6) did not improve D compared to use of IX in the Receiving Sheet A (Test 3).

Moreover, use of appreciable amounts of IX in the Activator (Test 6) prevented development of the outer emulsion layer 16 to the extent that high yellow minimum density (1.23) was obtained in the print. Moreover. when the Activator XI contained neither development arrestor nor antifoggant (Test '2) low D was obtained due to an overall fog level compared to use of Activator II containing antifoggant (Test 4).

COMPOUND I: 4'-methylphenylhydroquinone COMPOUND IX: 1-phenyl-5-mercaptotetrazole COMPOUND X: Z-mercaptobenzothiazole ACTIVATOR I: 3.5% hydroxyethylcellulose (Hercules type 250, high viscosity); 4.5% NaOH; 2.0% benzotriazole (NF-1) (1895-141-1) ACTIVATOR II: Activator I 2.0% 1-phenethyl-2- picolinium bromide (Q l) (1895-144-2, 1895-147-1) ACTIVATOR III: Activator 1 2% 1-benzyl-2-picolinium bromide (Q-2) (1895-141-3) ACTIVATOR VII: Activator III 1.0% sodium thiosulfate (1895-141-6) ACTIVATOR IX: Activator II 0.005% l-phenyl-S- mercaptotetrazole (1895-144-2) ACTIVATOR X: Activator II 0.05% l-phenyl-S-mercaptotetrazole (1895-14-3) ACTIVATOR XI: 3.5% hydroxyethylcellulose (Hercules type 250, high viscosity); 4.5% NaOH; 2.0% l-phenethyl-Z-picolinium bromide (Q-l) (J895-1444) ACTIVATOR XII: Activator XI 0.2% nitrobenzimidazole (NF-2) (J895-1472) ACTIVATOR XIII: Activator XI .2% benzimidazole ACTIVATOR XIX: Activator XI 0.2% imidazole RECEIVING SHEET A: A white pigmented cellulose ester support carrying a layer containing 300 mg./ft. gelatin, 300 mg./ft. poly-4-vinylpyridine and 15 mg./ft. 1-phenyl-5-mercapotetrazole (K3 19-3 1-1) RECEIVING SHEET B: A white pigmented cellulose ester support carrying a layer containing 300 mg./ft. gelatin, 300 mg./ft. poly-4-vinylpyridine and 15 mg./ft. 1-phenyl-5-mercapotetrazole plus 100 mg./ft. l-phenethyl-Z-picolinium bromide (J 895141-3) RECEIVING SHEET C: A white pigmented cellulose ester support carrying a layer containing 300 mg./ft. gelatin, 300 mg./ft. poly-4-vinylpyridine (J 895-141-6) RECEIVING SHEET D: A white pigmented cellulose ester support carrying a layer containing 300 mg./ft. gelatin, 300 mg./ft. poly-4-vinylpyridine and 15 mg./ft. 2-mercaptobenzothiazole (K441-182) TABLE I Neutral Scale Test No. Negative Activator Receiving Sheet Dmin Din Red Green Blue Red Green Blue 756 (MPHQ) XI (Q1) A pd. IX 19 20 41 1. 58 1. 13 1. 756 (MPHQ) XI (Q,1) C (Mordant only) .21 23 .37 1. 24 94 1. 27 756 (MPH II (NF- A pd. IX .19 .20 .25 1.97 1.60 1.93 756 (MPHQ) I (NF1) C (Mordant only) .17 .20 .24 1. 52 1. 52 2.07 (MPH IX (cpd. IX) do .18 .21 .25 1.41 1.58 2.13 756 (MPH X (cpd. IX) .....(10 17 .40 1.23 1. 53 1.67 2.18 756 (MPHQ) (NF- A (cpd. IX) 19 20 25 1. 97 1. 1. 93 756 (MPHQ) II (NF1) C (Mordant 0n1y) 17 20 24 1. 52 1. 52 2.07 339 (MPHQ) A (cpd. IX) 17 20 .27 1. 82 1. 48 1. 83' 339 (MPHQ) 16 20 36 1.54 1. 35 1. 339 (MPHQ) .16 21 41 1. 65 1. 40 1. .16 .21 51 1.39 1.15 1.83 .19 .20 .41 1. 58 1.13 1. 55 .69 1.15 1. 72 1.61 1.91 2.11 55 69 95 1. 42 1. 81 1. 99 53 .89 2. 32 1. 76 1. 97 2. 36 20 25 53 1. 68 1. 99 2. 49 55 69 95 1. 42 1. 81 1. 99 32 25 26 1. 71 1. 79 2.05 20 25 53 1. 68 1. 99 2. 49 19 20 41 1. 58 1. 13 1. 55 21 23 37 1. 24 94 1. 27 20 30 42 2.01 1. 99 2. 20 22 25 36 1. 94 1. 93 2. 14

23 EXAMPLE 2.--THE USE OF A RECEIVING SHEET CONTAINING A DEVELOPMENT ARRESTOR AND MORDANT Negative 756 was processed as in Example 1, with Activator II using Receiving Sheets A and C (Tests 7 and 8). The data of Table I shows that Compound ]X increased D in the presence of a mordant.

EXAMPLE 3.-USE OF VARIOUS DEVELOPMENT ARRESTORS A negative prepared as in Example 1 and designated 339 was processed with Activators II, XII, XIII, XIV and XI using Receiving Sheet A, containing Compound DC, (Tests 9l3). The data of the table show that the anti- 24 the resultthat the two development arrestors IX and X were found to give similar results as can be seen from the data of Tests 23 and 24 and from viewing the prints.

EXAMPLE 7.COMPA-RISON OF USE OF ANTI- FOGGANTS AND DEVELOPMENT ARRESTORS IN RECEIVING SHEET Samples of a negative prepared as in Example 1 were processed with Activator VII using control receiving sheets containing po1y-4-vinylpyridine mordant and experimental sheets containing this mordant plus the compounds shown in Table II (Tests l-17). The maximum densities of the neutral scale to red, green and blue light were recorded and the change in maximum density foggants of Tests 9-12 all produced beneficial results com- 15 (A D caused by the compounds is shown in Table H.

TABLE II Neutral Scale (AD-n) Test Compound Red Green Blue 1-phenyl-5-mereaptotetrazole 05 07 5-myristoylthio-l-phenyltetrazole 10 08 09 5-5 aeetylethylthio-l-phenyltetrazole 11 03 06 2-mereapto-5 phenyl-l, 3, 4-oxad1azole 15 21 Zmereaptonaphthll, 2]oxazole 11 05 03 2-mercaptobenzoxazole 09 07 16 2-(2-d.iearbethoxy)ethylmercaptobenzoxazole 11 04 07 Potassium iodide 12 19 24 Benzothizaole methiodide 32 28 Bls-(2-amino-5-iodopyridine hydro e) rc dide 09 18 21 Thiovarbiturie acid 19 08 06 Benzotriazole 15 07 15 Benzothiazole metho methyl sulfate 06 03 11 Thioacetanilide 02 06 15 7-mercapto-1, 3, 4, G-tetrazaindene- 05 03 99 l-methyl-l, 2, 3, fi-tetrahydrol-l, 3, 5-triazine-4-thiol 1. 07 83 85 l-cyelohexyl-l, 2, 3, fi-tetrahydro-l, 3, 5-triazine-4-thiol 1. 19 1. 31 1.49

pared to Test 13 where no antifoggant was in the solution.

EXAMPLE 4.EFFEOT OF HYDROQUIN ONE DERIVATIVE IN NEGATIVE Negative 371 (containing MPHQ and prepared as in Example 1) and 368 prepared in the same manner but containing no MPHQ in layer 19, were processed with Activator I and Receiving Sheets A and B with the results shown in Table I (Tests 14-17). In the presence of MPHQ an appreciable decrease in D is obtained (Tests 14 vs. 15). Moreover, the print of Test 15 showed reduced color contamination. When the quaternary salt Q-l was present, reduced color contamination, drop-01f and minimum density was obtained (Tests 14 vs. 16). When both MPHQ and Q-l were present an even greater increase in D and reduction in D was obtained (Test 15 vs. 17). Also the print of Test 17 showed even less color contamination and drop-off.

EXAMPLE 5.EFFECT OF QUATERNARY SALT Negatives prepared as in Example 1 (756) were processed with Activators I, II and XI using Receiving Sheets A, B and C in the combinations and with the results shown in Tests 18-22 of Table I. The data show that very substantial improvement in D and D were obtained when the activator contained an antifoggant (NF-1) and the Receiving Sheet contained a development arrestor (DO i.e. Tests 19 to 22 vs. 18. Less color drop-off and color contamination also showed in the prints. However, useful results were observed from a system where the activator did not contain antifoggant while the receiving sheet contained development arrestor and quaternary compound.

EXAMPLE 6.USE OF Z-MERCAPTOBENZO- THIAZOLE A negative 646 prepared as in Example 1 was processed with Activator HI using Receiving Sheets A and D with The data of Tests 1-10 clearly show the substantial improvement in D obtained by use of the development arrestors in the receiving sheets. Tests 11-17 show that the antifoggant compounds either reduced or only slightly improved D accompanied by other disadvantages. Thus, benzothiazole reduces D compared to increasing D when it is present in the activator (Tests 1, 2, Table I). Thiobarbituric acid in addition to reducing D (Table II, Test 11) produced overall yellow strain on the print. Thioacetanilide slightly increased the D but disadvantageously increased minimum density of the prints. The compounds of Tests 15, 16 and 17 reduced D very greatly as can be seen.

The unique results obtained with the heterocyclic quaternary ammonium compound forming methylene bases may be due to their reaction with two moles of a quinone (obtained by oxidation of a dye developer or other hydroquinone derivative) to form an addition product of the quinone and the methylene base and regenerate a hydroquinone, as shown by James, Snell and Weissberger J.A.C.S. 60 2084 (1938).

The emulsion addenda described in the Whitmore et al. US. Patent application Serial No. 734,141, filed May 9, 1958, now abandoned, and French Patent 1,205,755, August 17, 1959, including the noble metal salts, stannous salts, polyamides, optical sensitizing dyes, mercury and azaindene stabilizing compounds, quaternary ammonium salt and polyethylene glycol speed-increasing compounds, plasticizers, hardeners, coating aids in colloid vehicles disclosed therein may be used advantageously in the silver halide emulsion layers and adjacent layers of the sensitive elements of the present invention.

What we claim is:

1. A multicolor diffusion transfer process which comprises exposing to a subject a sensitive element including a plurality of light-sensitive silver halide emulsion layers sensitive to different regions of the spectrum, dye developers being contiguous to the silver halide of each emulsion layer, said dye developer being a compound which is both a silver halide developing agent and a dye, applying an alkaline solution to the emulsion layers while they are in superposed contact with a reception layer containing a silver halide development arrestor diffusible in the alkaline solution selected from the group consisting of (a) amercaptoazole,

(b) an azole that hydrolyzes in alkaline solution to form a mercaptoazole,

(c) an iodide, and

(d) an iodine-containing compound that releases an iodide in alkaline solution,

thereby developing the silver halide and rendering the dye developers non-diffusing in the region of development, the development arrestor difiusing to the emulsion layers and stopping further development, allowing the dye developers in the undeveloped regions to transfer imagewise by diffusion and in register to the reception layer, and removing the reception layer to obtain a multicolor image thereon composed of the dye developers.

2. The process of claim 1 wherein the development arrestor is a member of the class consisting of iodides diffusible in the alkaline solution and compounds releasing in alkaline solution iodides difi'usible in the alkaline solution.

3. The process of claim 1 wherein the development arrestor is a member of the class consisting of mercapto azoles ditfusible in alkaline solution and azoles hydrolyzing in the alkaline solution to yield mercaptoazoles diffusible in alkaline solution.

4. The process of claim 1 wherein the alkaline solution contains an antifoggant for silver halide.

5. The process of claim 1 wherein the sensitive element contains red, green and blue light-sensitive emulsion layers coated in order on a support, and the dye developers are subtractively colored and present in contiguous layers underlying the emulsion layers.

6. The process of claim 1 wherein a substantially colorless and substantially water-insoluble hydroquinone soluble and diflFusible in the alkaline solution is present in a layer of the sensitive element.

7. A multicolor diifusion transfer process as described in claim 1 wherein the development arrestor is selected from the group consisting of 1) 1-phenyl-5-mercapto-1,2,3,4-tetrazole,

(2) S-myristoylthio-l-phenyl-l,2,3,4-tetrazole,

(3) S-B-acetylethylthio- 1-phenyl-1,2,3 ,4,-tetrazole,

(4) 3-mercapto-5-pheny1-1,3,4-oxadiazole,

(5) 2-mercaptonaphth( 1,2,) oxazole,

(6) Z-mercaptobenzoxazole,

(7) 2-mercaptobenzothiazole,

(8) 2-(2'-dicarbethoxy)ethylmercaptobenzoxazole,

(9) Potassium iodide,

(10) Benzothiazolium methiodide, and

( 1 1) Bis(2-amino-5-iodopyridine hydroiodide) mercuric iodide.

8. The process of claim 1 wherein the alkaline solution contains a quaternary ammonium compound diifusible in the alkaline solution.

9. In the processing of an exposed photographic element comprising a support, superposed red, green and blue light-sensitive silver halide emulsion layers, and a dye developer which is both a silver halide developing agent and a dye contiguous to the silver halide of each of said silver halide emulsion layers, said processing being effected by treating said photographic element with an aqueous alkaline solution, developing latent images in the regions of exposure of said silver halide emulsion layers and thereby immobilizing dye developers in said regions of exposure, dye developers in undeveloped regions diffusing imagewise to the surface of said photographic element, and transferring the resulting difiused images from said undeveloped regions in register to a dye developer receiving sheet superposed on said photographic element, the improvement which comprises utilizing 1- phenyl-5-mercapto-,2,3,4-tetrazole as a silver halide development arrestor in said receiving sheet.

References Cited by the Examiner UNITED STATES PATENTS 2,334,864 l1/1943 Carroll et al 96109 X 2,636,821 4/1953 Sargent 9622 2,725,290 11/1955 Smith 9622 2,784,090 3/1957 Carroll 96107 2,886,437 5/1959 Piper 9666 2,983,606 5/1961 Rogers 9629 3,017,270 1/ 1962 Tregillus et a1 9629 3,020,155 2/1962 Yackel et al 9629 NORMAN G. TORCHIN, Primary Examiner.



Assistant Examiners.

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U.S. Classification430/240, 430/218, 430/219, 430/239
International ClassificationG03C8/02, G03C8/16, G03C8/52, G03C8/00
Cooperative ClassificationG03C8/52, G03C8/16
European ClassificationG03C8/52, G03C8/16