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Publication numberUS3173786 A
Publication typeGrant
Publication dateMar 16, 1965
Filing dateAug 22, 1960
Priority dateAug 22, 1960
Also published asDE1174160B
Publication numberUS 3173786 A, US 3173786A, US-A-3173786, US3173786 A, US3173786A
InventorsGreen Milton, Howard G Rogers
Original AssigneePolaroid Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Color diffusion transfer process, element and composition therefor
US 3173786 A
Abstract  available in
Images(9)
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Claims  available in
Description  (OCR text may contain errors)

United States Patent 3,173,786 COLOR DIFYUSIGN TRANSFER PROCESS, ELE- MENT AND COM'PGSITIQN THEREFOR Milton Green, Newton Highlands, and Howard GJRogers,

Weston, Mass., assignors toPolaroid Corporation, Cambridge, Mass, a corporation of Delaware No Drawing. Filed Aug. 22, 1960,Scr. No. 56,851

.31 Claims. (Cl. 9-6-3) The present invention is concerned with photography and, more particularly, with color diifusion-transfer processess.

One object of the present invention is to provide processes for improving the density of transfer images which are produced by diffusion-transfer processes utilizing dye developers.

Another object of the invention is to provide processes for improving the color separation and highlights of multicolor transfer images produced by difiusiontransfer processes utilizing dye developers.

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

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description.

The copending application of Howard G. Rogers, Serial No. 748,421, filed July 14-, 1958, now US. Patent No. 2,983,606, issued May 9, 1961, which is a continuationin-part of U.S. application, Serial No. 415,073, filed March 9, 1954 (now abandoned); discloses and claims processes wherein dye developers (i.e., dyes which contain in the same molecule a silver halide developing function and the chromophoric system of a dye) are used to form color-transfer images. In such processes, a photosensitive element is exposed to create therein a latent image. The latent image is developed in the presence of a dye developer; and an imagewise distribution of unrcacted dye developer, from which the postive image may be created, is formed. At least a portion of the unreaoted dye developer is transferred to a superposed image-receiving layer to create thereon a positive image.

in a useful mode of carrying out processes of this type, a photosensitive element containing a silver halide emulsion is exposed and wetted by a liquid processing composition, for example, by immersing, coating, spraying, flowing, etc., in the dark and the exposed photosensitive element is superposed prior to, during, or after Wetting, on a sheetlike support element which may be utilized as an image-receiving element. In a preferred embodiment, the photosensitive element contains a layer of dye developer and the liquid processing composition is applied to the photosensitive element in a uniform layer as the photosensitive element is brought into superposed relationship with an image-receiving element. It is also contemplated to utilize the dye developer in the liquid processing composition where monochromatic images are desired. The liquid processing composition permeates the emulsion to initiate development of the latent image contained therein. The dye developer is immobilized or precipitated in exposed areas as a consequence of the development of the latent image. This immobilization i apparently, at least in part, due to a decrease in the solubility of the dye developer upon oxidation. In unexposed and partially exposed areas of the emulsion, the dye developer is at least partly unreacted, and thus provides an imagewise distribution of unoxidized dye developer, dissolved in the liquid processing composition,

3,173,786 Patented 'Mar. 16, 1965 as a function of the point-to-point degree of exposure of the silver halide emulsion. At least :part of this imagewise distribution of unoxidized dye developer is transferred, by 'imbibition, to a superposed image-receiving layer or element, said transfer substantially excluding oxidized dye developer. The image-receiving element receives a depthwise diliusion from the developed emulsion of unoxidized dye developer without appreciably disturbing the imagewise distribution thereof to provide a reversed or positive color image of the developed image.

Multicolored transfer images may be produced through various methods 'by using at least two differentially sensitized silver halide emulsions and developing each emulsion in the presence of a differently colored dye dveloper. One method comprises using integral photosensitive elements and processes such, for example, as those claimed and disclosed in the copending U.S. application of Edwin H. Land and Howard G. Rogers, Serial No. 565,135, filed February 13, 1956, wherein at least two selectively sensitized photosensitive strata are superposed on a single support and are processed with a single processing solution and transferred to a common image-receiving layer. A suitable arrangement of this type comprises a support carrying a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum, and -a blue-sensitive silver halide emulsion stratum, each of said emulsions having associated therewith, respectively, a cyan dye developer, n magenta dye developer, and a yellow dye developer. In one of the preferred embodiments of photosensitive elements used in such processes, the dye developer is disposed in a separate alkali-permeable layer, preferably behind the photosensitive silver halide emulsion with which it is associated. The processes of the present invention are especially useful in processing these integral multilayer photosensitive elements.

It has now been found that 'the density of highlights of the transfer images produced by such dye developer processes may be substantially improved by carrying out the development in the presence of at least one onium compound and especially in the presence of at least one onium compound selected from the group consisting of quaternary ammonium, quaternary phosphonium, and tertiary sulfonium compounds.

It is believed that such onium compounds interact with the dye developers to form salts thereof and that the improvements in density and highlights are at least due in due in part to the client of such salt formation on the solubility and diffusibility of the dye developers.

Onium compounds have 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-aotive quaternary ammonium compounds as development accelerators and U.S. 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 results and especially the increase in density ob tained by using onium compounds in conjunction with the dye developers in the diffusion-transfer processes of this invention are worthy of note. In the processes disclosed in the above-mentioned U.S. 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, the increase in density which is referred to is that which takes place in the positive image and is primarily the result of increased transfer of the dye developer from and 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 compoundsas sensitizers or development accelerators. Further, the increase in density in the present processes is not the result of improved surface activity due to the onium compounds because, as will be hereinafter shown, 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 so act with the dye developers to inhibit transfer of such developers from exposed areas and thus improved the highlights, is similarly unexpected. This improvement in highlights is believed to be due at least in part to the ability of the oniums, through salt formation with the dye developers, to control, especially in exposed areas, the diffusibility 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.

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

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 lauryldimethylsulfonium p-toluene sulfonate, nonyl-dimethylsulfonium ptoluene sulfonate and octyldimethylsulfonium p-toluene sulfonate, butyldimethylsulfonium bromide, triethylsulfonium bromide, tetraethylphosphonium bromide.

The onium compounds may be used as the free base 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 effects on the emulsion and suitable precautions should be taken. Especially good results were obtained when the onium compounds were employed as the bromide. When using onium compounds, which have an anion other than bromide, it has been found advantageous in certain instances to add a small amount of potassium bromide.

Generally, the effect of the onium compounds on the density and highlights will vary with the molecular size of the particular onium cation employed. Usually the increase in density will be especially marked as the molecular size of the onium cation decreases. Conversely, the cleanness of the highlights will be especially noticeable with increasing molecular size. Onium cations of intermediate molecular size may provide an especially marked improvement in both the density and highlights. Generally, the cation of the onium compounds which will especially promote increased density, will be devoid of hydrophobic chains having, for example, more than 3 carbon atoms. As examples of such low molecular size onium compounds, mention may be made of: l-ethylpyridinium p-toluene sulfonate, l-propyl-pyridinium p-toluene sulfonate, N-phenyl-N,N,N-trimethylammonium p-toluene sulfonate, l-propylpyridinium bromide, 1-ethyl-2- methylpyridinium bromide, l-(fi-hydroxyethyl)-pyridinium bromide, 1-ethyl-2,3-dimethylpyridinium p-toluene sulfonate, 1-ethy1-Z-methoxypyridinium bromide, tetraethylammonium bromide, dimethyldiethylammonium ptoluene sulfonate, 1,1-diethylpiperidinium bromide, l-ethyl pyridazinium methosulfate, ethyldimethylsulfonium bromide, methyl-diethylsulfonium p-toluene sulfonate, trimethylsulfonium bromide, tetramethylphosphonium bromide, ethyltrimethylphosphonium bromide, diethyldimethylphosphonium p-toluene sulfonate and propyltrimethylphosphonium bromide.

The cation of oniums which will especially promote improved highlights generally will include a hydrophobic chain comprising at least, for example, 4 carbon atoms. In a preferred embodiment the hydrophobic chain will comprise between 4 and 16 carbon atoms and, more preferably, between about 4 and about 10 carbon atoms. As examples of such hydrophobic chains, mention may be made of pentyl, octyl, nonyl decyl, etc., groups. The hydrophobic chain is preferably substituted directly on the nitrogen, sulfur, or phosphorous atoms. However, in certain instances such, for example, as in heterocyclic quaternary ammonium compounds, it may be present else- Where in the molecule, e.g., on the heterocyclic ring. The upper limit on the molecular Weight and length of the hydrophobic chain in such onium compounds is preferably determined by the solubility and mobility of the complex of such compounds and the dye developers in the aqueous alkaline processing solution. As examples of onium compounds containing a hydrophobic chain, mention may be made of I-octyLZ-methylpyridinium p-toluene sulfonate, octyltrimethylammonium bromide, lauryltrimethylammonium bromide, l-octyl-l-methylpiperidinium methosulfate, octyltrimethylphosphonium bromide, and octyldimethylsulfonium p-toluene sulfonate.

Hydrophobic substituents which have been found particularly useful in the onium compounds of this invention are the aralkyls .and especially the phenalkyls. Onium compounds containing such substituents have been found especially useful in producing a marked improvement in both the density and the highlights. Particularly good results are obtained when the phenalkyl substituents are selected from those wherein the alkyl portion of the molecule comprises 1 to 4 carbon atoms, e.g., benzyl, phenethyl, phenylpropyl and phenylbutyl radicals.

A class of onium compounds which has been found especially useful are those which contain a reactive methyl group, Le, a methyl group which in allrali is capable of forming a methylene base. Such compounds, in addition to improving the density of highlights, also provide improved color separation, i.e., the transfer of the dye de velopers is more closely controlled by the silver halide emulsion with which each is associated. Pyridiniurri quaternary ammonium compounds having a methyl substituent in the 2. or 4 positions of the heterocyclic ring have been found especially useful as such onium compounds possessing a reactive methyl group. The preerred 2 and 4 methyl-substituted pyridinium compounds are those wherein the nitrogen atoms is substituted by a phenalkyl group and especially by a phenalkyl in which the alkyl portion of the molecule comprises 1 to 4 carbon atoms. Preferred compounds Within this group are l-(fi-phenethyl)-2-methylpyridiniurn bromide and 1- benzyl-2-methylpyridinium bromide.

In one embodiment of this invention a combination of onium compounds is employed. Through the use of such a combination, one may strike a desired balance between the increase in density and the improvement in the highlights. One such combination comprises using an onium compound of small molecular "size such, for example, as those mentioned above, which are devoid of hydrophobic chains comprising more than 3 carbon atoms, with an onium compound containing a hydrophobic chain of at least 4 carbon atoms. One of the pre ferred combinations comprises using an onium compound of small molecular size with a large onium compound such as mentioned above which also contains a reactive methyl group. Such a combination is particularly eifective in producing transfer images having increased density and improved highlights and color separation. In an especially useful combination, the onium compound possessing the active methyl group is substituted by a phenalkyl group. As an example of such an especially use ful combination, mention may be made of the use of N-ethylpyridinium bromide in combination with N-([i phenethyl)-2-methylpyridinium bromide. In a further modification of the preferred combination, a higher molecular weight onium compound, e.g., lauryl-trimethylammonium bromide is also used in the combination. The use of such higher molecular weight onium compounds further improves the highlights of the transfer image.

Generally, the ability of the onium compounds to improve the color separation and highlights will be proportional .to the ease with which such onium compounds are adsorbed on the silver halide grains of the light- I sensitive emulsions.

In certain instances, it may be desirable to use, in conjunction with the onium compounds, an aqueous alkaline processing solution which includes in part at least one organic, water-miscible solvent. As examples of solvents which have been found useful in this embodiment, mention may be made of dioxane, N,N-dimethy1 ethanolamine, N,N-diethyl ethanolamine, tetrahydrofuran, and diethylaminopropanediol. Processing solutions comprising about of the organic, water-miscible solvent have been employed; however, it should be understood that this percentage may be varied to suit particular needs.

In the abovementioned copending US. application Serial No. 748,421, it is disclosed that the density, color separation and highlights of transfer images, which are produced in dye developer processes, may be substantially improved by carrying out the process in the presence of at least one silver halide developer in addition to the dye developers. The present invention provides another method of bringing about these improvements which does not necessitate the use of such silver halide developers. In a further embodiment of this invention, additional improvement may be made in the transfer images by using at least one onium compound in combination with at least one silver halide developer. As examples of combinations of onium compounds and silver halide developers which have been found especially useful in the processes of this invention, mention may be made of the use of I-(B-phenethyl)-2-methylpyridinium bromide with trimethylhydroquinone and the use of l-(B-phenethyl)-2-methylpyridiniuni p-toluene sulfonate with 4'- methylphenylhydroquinone.

In carrying out the processes of this invention, there is no necessity that the onium compounds be present in the photosensitive element at the time of exposure. As a result of this, the onium compounds may be introduced into the processes by various methods. In one embodiment, which has been found especially useful, the onium compounds are incorporated directly into the processing solution and inbibed into the photosensitive element along with the other reagents used. In another embodiment, the onium compounds are disposed in the imagereceiving element and during processing they are solubilized therefrom and transferred to the photosensitive element so as to be present during development. In still another embodiment, the onium compounds are disposed in the photosensitive element, e.g., in special reagent layers, in the dye developer layers, etc. When using the latter embodiment, care should be taken to prevent the onium compounds from desensitizing the emul- 510115.

In carrying out the processes of this invention, the amount of onium compounds used may be varied to suit particular needs. Generally, good results have been obtained by using processing solutions comprising about 1 to 10% of the onium compounds and especially good results have been obtained by using processing solutions comprising 2 to 4% of such compounds.

The previously mentioned improvements in density were especially marked in processes wherein an antifoggant was used in combination with the onium compounds. Such antifoggants tend to offset the fogging which may occur as an effect of the onium compounds ability to accelerate development. As examples of antifoggants which have been found useful, mention may be made of thioacetanilide, S-methylbenzimidazole, S-nitrobenzimidazole, 2 aminobenzimidazole and 1 phenyl 5- mercaptotetrazole.

The following non-limiting examples illustrate processes within the scope of the present invention:

Example 1 A photosensitive element was prepared by coating 2. gelatin-subcoated cellulose acetate film support with the following coating solutions:

(1) A te-trahydrofuranacetone solution (1 to l by volume) comprising 5.5% of 1,4-bis-[,3-(2',5-dihydroxyphenyl)-isopropylamino]-anthraquinone (a cyan dye deveolper), about 0.8% of Resofiex 296 (trade name of Cambridge Industries (10., Inc., Cambridge, Mass, for an alkyd resinous plasticizer) and 2% cellulose acetate hydrogen phthalate.

(2) A red-sensitive silver halide emulsion.

(3) An acetone solution comprising 2% cellulose acetate hydrogen phthalate, 0.75% cellulose acetate and 0.05% S-nitrobenzimidazolc.

(4) A 2% aqueous polyvinyl alcohol solution.

(5) A 'tetrahydrofuran-acetone solution (1 to l by volume) comprising 3.5% of 2-'[p-(2',5'-dihydroxyphenethyD-phenylazo]-4-n-propoXy-l-naphthol (a magenta dye developer), 2% of cellulose acetate hydrogen phthalate and 0.4% of Resofiex 296.

(6) A green-sensitive silver halide emulsion.

(7) An acetone solution comprising 2% cellulose acetate hydrogen phthalatc, 0.5% cellulose acetate and 0.04% 5-nitrobenzimidazole (8) A 2% aqueous polyvinyl alcohol solution.

(9) A tetrahydrofuran solution comprising 3% of lphenyl-3-N-n-hexyl-carbamyl 4 [p-(2,5-dihydroxy phenethyD-phenylazo]-5-pyrazolone (a yellow dye deoxymethyl polyhexamethylene adipamide.

veloper), 2% of cellulose acetate hydrogen phthalate and 0.4% Resoflex 296.

' (10) Ablue-sensitive'silver halide emulsion.

The above photosensitive element was exposed and then processed by spreading an aqueous processing solution comprising I Percent 1-phenyl-3-pyrazolidone 1.2 2,5-bis-ethyleniminohydroquinone 0.9

S-nitrobenzhnidazole 0.125

l-ethylpyridinium bromide 2.5 Sodium carboxymethyl cellulose 3.0 Sodium hydroxide 3.0

Example 2 A photosensitive element was prepared, exposed and processed in a manner similar to that employed in Example 1 except that an aqueous processing solution comprising:

Percent l-ethylpyridinium p-toluene sulfonate 3.0 -nitrobenzimidazole 0.12

Sodium hydroxide 3.0 Sodium carboxymethyl cellulose 5.0

was employed.

Example 3 A photosensitive element was prepared, exposed and processed in a manner similar to that employed in Example 1 except that an aqueous processing solution comprising:

Percent Sodium carboxymethyl cellulose 5.25 Sodium hydroxide 4.0

1-butylpyridinium p-toluene sulfonate 5.0

was employed.

Example 4 A photosensitive element was prepared and processed in a manner similar to that employed in Example 1 except that an aqueous processing solution comprising:

Percent Sodium hydroxide 3.0 Sodium carboxymethyl cellulose 5.0 1,1-ethylenebis-(pyridinium bromide) 5.0

was employed.

Example 5 A photosensitive element was prepared and processed in a manner similar to that employed in Example 1 except that an aqueous processing solution comprising:

Example 6 A photosensitive element was prepared and processed in a manner similar to that employed in Example 1 except that an aqueous processing solution comprising:

Percent Sodium hydroxide 3.0 Sodium carboxymethyl cellulose 5.0 1,2,G-trimethylquinolinium p-toluene sulfonate 5.0 S-nitrobenzimidazole 1.0 was employed. a

8 Example 7 An aqueous processing solution comprising:

Percent Sodium hydroxide 4.0 Sodium carboxymethyl cellulose 3.0 /3-Hydroxyethyl-trirnethylammonium chloride 8.0 l-(fi-phenethyl) 2-rnethylpyridinium bromide 5.0 S-methylbenzimidazole 0.5

was used to process an exposed photosensitive element such as employed in Example 1.

Example 8 An aqueous processing solution comprising:

Percent Sodium hydroxide 4.0 Sodium carboxymethyl cellulose 3.0 l-ethylpyridinium bromide 8.0 l-(B-phenethyl)-2-methylpyridinium bromide 5.0 S-methylbenzimidazole 0.5

was used to process an exposed photosensitive element similar to that employed in Example 1.

Example 9 An aqueous processing solution comprising:

Percent Sodium hydroxide 4.0 Sodium carboxymethyl cellulose 3.0 l-ethylpyridinium bromide 8.0 l-(fi-phenethyl)-2-methylpyridinium bromide 5.0 Cetyl-trimethylammonium bromide 2.0 S-methylbenzimidazo-le 0.5 Sodium thiosulfate 1.0

was used to process an exposed photosensitive element prepared in a manner similar to that employed in Example l.

The following examples utilize a photosensitive element prepared in a manner similar to that disclosed above except that (a) the dye developers were dissolved in a Waterimmiscible solvent and dispersed in gelatin rather than placed in a cellulose acetate hydrogen phthalate layer; (b) a single gelatin interlayer Was used in place of the polyvinyl alcohol and cellulose acetate hydrogen phthalatecellulose acetate layer; and (c) the outer blue-sensitive emulsion was overcoated with a thin gelatin layer comprising about 15 mg. per square foot of 4-methylphenylhydroquinone.

Example 10 n An all gelatin photosensitive element similar to that described above was exposed and processed by spreading an aqueous processing composition comprising:

Water cc Sodium carboxymethyl cellulose gms 4.8 Sodium hydroxide gms 4.8 1-( ,B-phenethyl)-2-methylpyridinium bromide gms-.. 2.4 S-nitrobenzimidazole gm 0.24 Hexamethylenetetramine gms- 6.0

Example 11 A processing solution comprising:

Water cc 100 Sodium hydroxide gms 4.0 Sodium carboxymethyl cellulose gms 2.5 l-ethylpyridinium bromide gms 5.0 l- (fi-phen ethyl -2-methylpyridinium bromide gms 4.0 5-nitrobenzimidazole gm 0.5 Tetrahydrofuran cc 10.0

was used to process an exposed photosensitive element in a manner similar to that employed in Example 10.

Example 12 A photosensitive element similar to that employed in Example was processed in a manner similar to that employed in Example 10 except using a processing solution comprising:

Example 14 The process of Example 10 was repeated except that an aqueous processing solution comprising:

Percent Sodium hydroxide 4.0 Sodium carboxymethyl cellulose 4.0 Tetrahydrofuran 10.0 Cetyl-dimethyl-benzylammonium bromide 1.0 S-nitrobenzimidazole 0.2 Sodium thiosulfate 1.0

was used.

Example 15 The process of Example 10 was repeated except that an aqueous processing solution comprising:

Percent Sodium hydroxide 4.0 Sodium carboxymethyl cellulose 4.0 Sodium thiosulfate 1.0 l-(B-phenethyl)-2-methylpyridinium p-toluene sulfonate 2.0 1-(B-phenethyl)-3-methylpyridinium bromide 2.0 S-nitrobenzimidazole 0.2 Hexamethylenetetramine 5.0

was used.

Example 16 The process of Example 10 was repeated except that an aqueous processing solution comprising:

Percent Sodium hydroxide 4.0

Sodium carboxymethyl cellulose 4.0

Sodium thiosulfate 1.0 1ethyl-2,4,6-trimethylpyridinium p-toluene sulfonate 2.0

Hexamethylenetetramine 5.0

was used.

Example 17 The process of Example 10 was carried out except that an aqueous processing solution comprising:

Percent Sodium hydroxide 4.0 Sodium carhoxymethyl cellulose 5.5 Triphenyl-phenacyl-phosphonium chloride 4.4 S-nitrobenzimidazole 0.1 Tetrahydrofuran 10.0 Hexamethyienetetramine 5.0

was used.

Example 18 The process of Example 10 was repeated except that an aqueous processing solution comprising the followmg:

Percent Sodium hydroxide 4.0 Sodium carboxymethyl cellulose 3.5 T-riethylsulfonium tosylate 4.2 S-nitrobenzimidazole 0.5 was employed.

Each of the transfer images produced in the above examples showed substantial improvements over similar transfer images produced without the use of the onium compounds.

It should be noted that in Example 4, the process is carried out in the presence of a compound containing two quaternary ammonium radicals. The term onium compound as used herein is intended to include compounds containing one or more onium radicals.

As examples of additional onium compounds which have been similarly tested and found useful, mention may be made of the following:

p-Chlorophenacyl pyridinium bromide Z-methylbenzothiazole-N-B-carboxyethobromide Z-methylbcnzothiazole-N-carboxymethobromide l-benzylpyridinium bromide l-benzyl-a-picolinium bromide 1,2-di-(2-[N-benzyH-pyridinium)-1,2-ethane-diol bromide l-mcthyl pyridinium tosylate lnethyl u-picolinium tosylate l-methyl-y-picolinium tosylate Carboxymethyl-triphenyl-phosphonium bromide l-rnethyl-2,6-lutidinium p-toluene sulfonate 2,3,4-trimethylthiazole tosylate Diethyl-carboxymethyl sulfoniurn bromide N-r'nethyl-Z-benzylmercaptothiazoliniurn methyl sulfate N- nethyl-Z-methylmercaptothiazoline methyl sulfate l-benzyl Z-ethylpyridinium bromide l-methoxy-a-picolinium methosulfate 6-methoxy-1- (fi-phenethyl -quinolinium bromide phenylene diamrnonium bromide 1- js-phenethyl -a-picolinium perchlorate l-benzyl-4-n-propyl pyridinium bromide l-ethyl-a-picolinium bromide l-methyl-a-picolinium bromide l-n-propyl-wpicolinium bromide l-benzyl-Z-benzyl pyridinium bromide 1-benzyl-4-benzyl pyridinium bromide l-benzyl-Z-n-amyl pyridinium bromide l-benzyloxy-a-picolinium bromide 1-( p-methylbenzyl)-a-picolinium bromide l-(y-phenoxypropyl)-a-picolinium bromide l (p-nitrobenzyl) -a-picolinium bromide 'l-laurylpyridinium p-toluene sulfonate Trimethylphenylammonium benzene sulfonate 2,6-dimcthyl-1-methyl quinoliniurn toluene sulfonate l-ethylpyridinium p-toluene sulfonate 1-methyl quinoliniurn chloride N-methylquinolinium methyl sulfate Trimethylphenylammonium hydroxide Tetrabutylammonium bromide Tetrabutylamrnonium hydroxide Tetraethylammonium hydroxide Cetyldimethylbenzylarnmonium chloride Tetra-n-propylammonium hydroxide l-methylpyridinium hydroxide N,N-dimethylpyrrolidinium hydroxide The effectiveness of the onium compounds in improving the density and color separation of the transfer images was evidenced by tests wherein areas of 3-color nega .tives such as used in Examples through 18 were exposed to (1) blue and green light only, (2) red and blue light only, and (3) red and green light only. Transfer images were prepared from one negative by using an aqueous processing solution containing no onium compounds (Solution A), from a second negative by using an aqueous solution containing the oniums (Solution B) and from a third negative by using an aqueous process ing solution comprising both the oniums and a watermiscible solvent (Solution C). The solutions comprised the following.

Solution A: Percent Sodium hydroxide 4.0 Sodium carboxymethyl cellulose 3.5 S-nitrobenzimidazole 0.5

Solution B:

Sodium hydroxide 4.0 Sodium carboxymethyl cellulose 3.5 l-ethylpyridinium bromide 5.0

=1-(,B-phenethyl)=2-methylpyridinium bromide 4.0

S-nitrobenzimidazole 0.5

Solution C:

Sodium hydroxide 4.0 Sodium carboxymethyl cellulose 5.5 l-ethylpyridinium bromide 1.0 1- (fl-phenethyl) -2-methylpyridinium bromide 4.0

S-nitrobenzimidazole 0.5 Tetrahydrofuran -Q 10.0

The analytical cyan, magenta and yellow densities of the resulting transfer images were measured by reflectance. Theoretically, only cyan dye developer should transfer from the negatives exposed to green and blue light, only magenta dye developer should transfer from the negatives exposed to red and blue light and only yellow dye developer should transfer from the negatives which were exposed to green and red light. The results obtained appear in tabular form below:

SOLUTION A SOLUTION C Density Exposure Cyan Magenta Yellow Blue and Green -Q 1. 31 0.12 0. 13 Red and Blue 0.20 0. 65 0. 12 Red and Green 0.12 0.16 1. 24

Similar tests wherein areas of the negative were exposed to blue, red and green light only, further exidenced the ability of the onium to increase the density and color separation.

The dye developers which are used in the processes of this invention, as noted above, are compounds which contain in the same molecule both the chromophoric system of a dye and also a silver halide developing function. Particularly useful results have been obtained when the onium compounds were. used in conjunction with dye developers comprising hydroxy-substituted benzenoid silver halide developing radicals and especially benzenoid silver halide radicals which are substituted by at least two hydroxy groups, e.g., hydroquinone and catechol radicals. Representative dye developers for use in the processes of this invention are disclosed in the previously mentioned US. application of Howard G. Rogers, Serial No. 748,421, now US. Patent No. 2,983,- 606. Additional useful dye developers are described in the following copending US.. applications:

Application Serial No. 824,785, filed July 3, 1959, now abandoned, in the names of Elkan R. Blout, Marilyn R. Cohler, Milton Green, Myron S. Simon and Robert B. Woodward.

Application Serial No. 612,045, filed September 25, 1956,

now abandoned, in the names of Elkan R. Blout, Milton Green andHowardG. Rogers.

Application Serial No. 612,052, filed September 25, 1956,

now abandoned, in the name of Myron S. Simon.

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

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

now abandoned, in the name of Helen P. Husek.

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

Application Serial No. 849,727, filed October 30, 1959 now abandoned, in the names of Elkan R. Blout and Myron S. Simon.

Application Serial'No. 1,442, filed January 11, 1960, in the names of Elkan R. Blout, Saul G. Cohen, Milton Green, Howard G. Rogers, Myron S. Simon and Robert B. Woodward.

The aqueous solutions used'in the processes of this invention are alkaline in nature and preferably should have a pH of at least 12. Some examples of alkaline materials which may be used are sodium hydroxide and potassium hydroxide, etc. In certain instances, an all quaternary processing solution may be employed by using quaternary hydroxides such as choline and tetrarnethylammonium hydroxide in place of the alkali metal hydroxides.

- As pointed out above, in one of the preferred embodiments of this invention, the onium compounds are used in combination with a silver halide developer in addition to the dye developers. The silver halide developers which have been found especially useful in this embodiment are the hydroxyl-substituted aryl developers, for example, toluhydroquinone, 5,8-dihydro-1,4-naphthohydroquinone, o-

13 toluthiohydroquinone, 5,6,7,8-tetrahydro-1,4-naphthohydroquinone, methoxyhydroquinone and 2,6-dimethylhydroquinone.

As will be understood, the onium compounds for use in the processes of this invention will be difiusible in the alkali-permeable film-forming materials which are used in the emulsion and other layers of the photosensitive element. Many alkali-permeable, film-forming materials are available for this use and the particular materials employed will vary depending on ones particular choice. As examples of film-forming materials, which have been used, mention may be made of gelatin, polyvinyl alcohol and cellulose acetate hydrogen phthalate.

It will be further understood that the oniums will be preferably colorless so as not to alter the color of the transfer image.

The coaction of the onium compounds with the dye developers was evidenced by a dye diffusion front test wherein the initial diffusion rate of 2-[p-(2',5'-dihydroxyphenethyl -phenylazo] -4-n-propoXy-1-naphthol (magenta dye developer) through gelatin was measured using a processing solution containing no quaternary ammonium compound and using a processing solution containing N-{S-phenethyl-a-picolinium bromide. It was found that the quaternary ammonium compound reduced the initial diffusion rate of the dye developer. It is believed that this reduction in the initial difiusion rate of the dye developers tends to prevent premature transfer and thus promotes an improvement in the highlights.

The processes of this invention are especially useful in composite film units intended for use in a Polaroid Land Camera, made by Polaroid Corporation, Cambridge 39, Massachusetts, or a similar camera structure such, for example, as the camera forming the subject matter of US. Patent No. 2,435,717, issued to Edwin H. Land on February 10, 1948. In general, such composite film units comprise a photosensitive element, such as the integral multilayer element heretofore described, an imagereceiving element and a rupturable pod containing an aqueous alkaline processing solution. The photosensitive element, image-receiving element and pod are so associated with each other that, upon processing, the photosensitive element may be superposed on the image-receiving element and the pods may be ruptured to spread the aqueous alkaline processing solution between the superposed elements. The nature and construction of the pods used in such rolls are well known to the art. See, for example, US. Patents Nos. 2,543,181 and 2,634,886, issued to Edwin H. Land.

The processes of this invention are further suitable for use with screen type photosensitive elements such as disclosed in the aforementioned application of Howard G. Rogers, Serial No. 748,421, now US. Patent No. 2,983,- 606, and also the copending application of Edwin E. Land, Serial No. 448,441, filed August 9, 1954, now US. Patent No. 2,968,554, wherein at least two selectively sensitized silver halide emulsions are arranged in the form of a screen and the color-providing substances, as in multilayer photosensitive elements, are preferably placed in a separate alkali-permeable layer in back of the photosensitive emulsion with which they are associated.

The term dye developer as used herein is intended to include color-shifted dye developers such as those disclosed in the copending application of Howard G. Rogers, Serial No. 789,080, filed January 26, 1959.

Since certain changes may be made in the above processes and products 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. A process of forming a transfer image in color which comprises exposing a photosensitive element comprising at least one silver halide emulsion, each of said silver halide emulsions having associated therewith a dye dei l veloper, each of said dye developers containing a hydroxysubstituted benzeuoid silver halide developing radical, developing said exposed photosensitive element, forming in undeveloped areas of each said silver halide emulsion, as a function of said development, an imagewise distribution of said associated dye developer in unoxidized, diilusible condition, and transferring, by diffusion, at least a portion of each said imagewise distribution of unoxidized dye developer to a superposed image-receiving layer to form said color transfer image, said process including the step of efi'ecting said development and transfer in the presence of at least one onium compound selected from .the group consisting of quaternary ammonium, quaternary phosphonium and tertiary sulfonium compounds, said onium compound being provided by application to said photosensitive element of an aqueous alkaline processing solution containing said onium compound.

2. A process as defined in claim 1 wherein said onium compound is added to said processing solution as the salt thereof.

3. A process as defined in claim 1 wherein said onium compound is a quaternary ammonium compound.

4. A process as defined in claim 3 wherein said quaternary ammonium compound is a tetraalkyl quaternary ammonium compound.

5. A process as defined in claim 3 wherein said quaternary armnonium compound is a heterocyclic quaternary ammonium compound.

6. A process as defined in claim 5 wherein said heterocyclic quaternary ammonium compound is a derivative of pyridine.

'7 A process as defined in claim 5 wherein said heterocyclic quaternary ammonium compound contains a phenalkyl substituent on the pentavalent nitrogen atom.

8. A process as defined in claim 7 wherein said phenalltyl substituent is a phenethyl group.

9. A process as defined in claim 7 wherein said phenallryl group is a benzyl group.

10. A process as defined in claim 1 wherein development is carried out in the presence of at least one substantially colorless silver halide developing agent in addition to said dye developer.

11. A process as defined in claim 1 wherein said hydroxy-substituted benzenoid silver halide developing radical in said dye developer is a hydroquinoyl radical.

12. A process as defined in claim 1 wherein said aqueous alkaline processing solution includes a water-miscible organic solvent.

13. A process as defined in claim 1 wherein said aqueous alkaline processing solution has a pH of at least l2.

14. A process as defined in claim 1 wherein said development is carried out in the presence of at least a first and a second onium compound, each of said onium compounds being selected from the group consisting of quaternary ammonium, quaternary phosphoniurn, and tertiary sulfonium compounds, the cation of said first onium compound being free of hydrophobic chains comprising more than 3 carbon atoms and the cation of said second onium compound containing a hydrophobic chain of at least 4 carbon atoms.

15. A process as defined in claim 14 wherein said first onium compound is a quaternary ammonium compound and said second onium compound is a quaternary ammonium compound.

16. A process as defined in claim 1 wherein said onium compound is free of hydrophobic chains comprising more than 3 carbon atoms.

17. A process as defined in claim 15 wherein the hydro phobic chain of said second onium compound comprises from 4 to 16 carbon atoms.

18. A process as defined in claim 15 wherein the hydrophobic chain of said second onium compound comprises from 4 to 10 carbon atoms.

19. A process as defined in claim 1 wherein an antifoggant is present in said processing solution with said onium compound.

20. A process as defined in claim 1 wherein said processing composition contains an alkali metal hydroxide.

21. A process as defined in claim 1 wherein said onium compound is present in said processing solution in a concentration of about 1% to 10%.

22. A process as defined in claim 1 wherein said onium compound is present in said processing solution in a concentration of about 2% to 4%.

23. A process as defined in claim 1 wherein said onium compound is colorless.

24. A photographic product comprising (a) a photosensitive element, said photosensitive el'ment comprising a support carrying at least one silver halide emulsion, each said silver halide emulsion having associated therewith a dye developer, each of said dye developers containing a hydroXy-substituted benzenoid silver halide developing radical, (b) an image-receiving element comprising a support carrying an image-receiving layer, and (c) a rupturable container releasably holding an aqueous alkaline processing solution, said aqueous alkaline processing solution including an onium compound selected from the group consisting of quaternary ammonium, quaternary phosphonium and tertiary sulfonium compounds, said photosensitive element and said imagereceiving element being capable of being superposed on each other with said rupturable containerpositioned therebetween so as to release said processing solution, upon rupture of said container, to permeate said silver halide emulsions and said image-receiving layer.

25. A photographic product as defined in claim 24, wherein said photosensitive element comprises a support carrying a red-sensitive silver halide emulsion stratum, 'a green-sensitive silver halide emulsion stratum, and a blue-sensitive silver halide emulsion stratum, each of said silver halide emulsions having associated therewith, respectively, a cyan dye developer, a magenta dye developer, and a yellow dye developer, each said dye developer being disposed in an alkali-permeable layer behind its associated silver halide emulsion.

26. A photographic product as defined in claim 20, wherein said onium compound is added to said processing solution in the form of a bromide salt thereof.

27. A photographic developer composition comprising an aqueous alkaline solution comprisin'gan alkali metal hydroxide, a dye developer, said dye developer containing a hydroxy-substituted benzenoid silver halide developing radical, and at least one colorless onium compound selected from the group consisting of quaternary ammonium, quaternary phosphonium and tertiary sulfonium compounds.

28. A photographic developer composition as defined in claim 27 wherein said composition includes sodium carboxymethyl cellulose.

29. A photographic developer composition as defined in claim 27 wherein said composition also includes a substantially colorless silver halide developing agent.

30. A process of forming a'transfer image in color which comprises exposing a photosensitive element comprising at least one silver halide emulsion, each of said silver halide emulsions having associated therewith a dye developer, each of said dye developers containing a hydroXy-substituted benzenoid silver halide developing radical, developing said exposed photosensitive element, forming in undeveloped areas of each said silver halide emulsion, as a function of said development, an imagewise distribution of said associated dye developer in unoxidized, diffusible condition, and transferring, by diffusion, at least a portion of each said imagewise distribution of unoxidized dye developer to a superposed image receiving layer to form said color transfer image, said process including the step of effecting said development and transfer in the presence of at least one onium compound selected from the group consisting of quaternary ammonium, quaternary phosphonium and tertiary sulfonium compounds, said onium compound being initially positioned in one of (a) said photosensitive element, (12) an aqueous alkaline processing composition applied to said photosensitive element to efiect said development and transfer, and (c) an image-receiving element including 'said image-receiving layer, said onium compound being transferred by diflusion from its initial location to each said silver halide emulsion, whereby the density of said color transfer image is increased.

31. A process as defined in claim 30 wherein said onium compound is initially positioned in said image-receiving layer, said aqueous alkaline processing solution is applied between said image-receiving element and said photosensitive element, and said onium compound is solubilized by said aqueous alkaline processing solution and transferred by diifusion to each said silver halide emul- SlOIl.

References Cited by the Examiner UNITED STATES PATENTS 2,197,809 4/40 McQueen 9666 2,271,622 2/42 Carroll et al 96107 X 2,271,623 2/42 Carroll 96--107 X 2,275,727 3/42 Carroll et al. 96107 X 2,371,740 3/45 Dearing 9661 2,648,604 8/53 Welliver et al. 9655 X 2,868,077 1/59 Ryan et al. 88-65 2,886,437 5/59 Piper et al. 9666 2,983,606 5/61 Rogers 9629 2,997,390 8/61 Land 9629 3,019,108 1/62 Dershowitz 96--29 3,034,894 5/62 Jeffreys 9699 3,043,692 7/62 Haas et al. 9629 3,061,437 10/62 Burness et al. 96108 3,061,453 10/62 Rogers 11734 3,065,075 11/62 Dershowitz 9629 3,077,400 2/ 63 Rogers et al. 96-==-3 FOREIGN PATENTS 554,935 8/57 Belgium. 221,880 5/59 Australia.

OTHER REFERENCES James et al.: JACS, 60, 2084-2093 (1938).

Mosher: American Dyestuff Reporter, Ian. 20 (1941), pp. P32-P38.

Willems: Science et Industr. Phot., 27, 487-488 (1956).

NORMAN G. TORCHIN, Primary Examiner.

PHILIP E. MANGAN, Examiner.

UNITED STATES PATENT oTTTcE CERTIFMATE 0i QQRREQTMN Patent No. 3,173,786 March 16, 1965 Milton Green et ale It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as correctedbelow.

Column 2, line 14, for "dveloper" read developer line 36, for "of" read and same column 2, line 46, strike out "due in"; column 3, line 17, for "improved" read improve column 5, line 14, for "atoms" read atom column 6, lines 53 and 54, for "deveolper" read developer column 9, line 29, after "that" insert a column ll, line 25, for "following." read following: column 12, line 12, for exidenced" read evidenced Signed and sealed this 26th day of Ocotber 1965!.

(SEAL) Attest:

ERNEST W, SWIDER EDWARD J. BRENNER Amzsting Qfficer Commissioner of Patents

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Classifications
U.S. Classification430/218, 430/941, 430/224, 430/239, 430/243, 430/469, 430/467
International ClassificationG03C8/16
Cooperative ClassificationY10S430/142, G03C8/16
European ClassificationG03C8/16