US3276872A - Photographic products, processes and compositions utilizing cesium hydroxide - Google Patents

Description

United States Patent "ice 3 276,872 PHOTOGRAPHIC PRbDUCTS, PROCESSES AND COMPOSITIONS UTILIZING CESIUM 'HY- DROXIDE George H. Fernald, Jr., Lincoln, Mass, assignor to Polaroid Corporation, Cambridge, Mass., a corporation of Delaware No Drawing. Filed Dec. 28, 1962, Ser. No. 247,867 23 Claims. (Cl. 96-29) This invention relates to photography and more particularly to products, compositions and processes useful in the development of photosensitive silver halide elements.

One object of the present invention is to provide novel processes and compositions for the development of silver halide emulsions, said developing compositions containing cesium hydroxide.

Another object of (the present invention is to provide novel processes and compositions for the development of silver halide emulsions, in which the novel developing composition is capable of developing an exposed silver halide emulsion and imparting a reversed or positive image of the developed image to a superposed image-receiving material, wherein the rate of diffusion transfer of colorproviding substances from said emulsion to said imagereceiving material to form the color image is substantially increased.

A further object is to provide novel processes and compositions suitable for use in preparing monochromatic and multichromatic photographic images.

Still another object is to provide novel photographic products containing cesium hydroxide as a component of the processing compositions.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the process involving the several steps and the relation and order of one or more of such steps with respect to each of the others, and the products possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of 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 photographic processes and compositions disclosed herein are particularly useful in the treatment of a latent image present in a photosensitive element, such as an exposed silver halide emulsion, whereby a positive dye image thereof may be imparted to another element, herein referred to as an image-carrying or image-receiving element.

US. Patent No. 2,983,606, issued May 9, 1961 to Howard G. Rogers, discloses diffusion transfer processes wherein a photographic negative material, such as a photographic element comprising an exposed silver halide emulsion, is developed in the presence of a dye developer to impart to an image-receiving layer a reversed or positive dye image of the developed image by permeating into said emulsion a suitable liquid processing composition and bringing said emulsion into superposed relationship with an appropriate image-receiving layer. The inventive concepts herein set forth provide novel liquid processing compositions for use in such processes.

In carrying out the process of this invention, a photosensitive element containing a silver halide emulsion is 3,276,872 Patented Oct. 4, 1966 exposed and wetted with the novel liquid processing composition of this invention, for example by immersing, coating, spraying, flowing, etc., in the dark, and the photosensitive element superposed, prior to, during or after wetting, on 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 thin, substantially uniform layer as the photosensitive element is brought into superposed position with an image-receiving element. The liquid processing composition permeates the emulsion to provide a solution of dye developer substantially uniformly distributed therein. As the exposed silver halide emulsion is developed, the oxidation product of the dye developer is immobilized or precipitated in the developed areas, thereby providing an imagewise distribution of unoxidized dye developer dissolved in the liquid processing composition. This immobilization is apparently due, at least in part, to a change in the solubility characteristics of the dye developer upon oxidation, and especially as regards its solubility in alkaline solutions. It may also be due, in part, to .a tanning effect on the emulsion by the oxidized developing agent. At least part of this imagewise distribution of unoxidized dye developer is transferred by imbibition, to a superposed image-receiving layer, said trans-fer substantially excluding silver or oxidized dye developer. The image-receiving layer receives a depthwise diffusion, from the emulsion, of unoxidized dye developer, without appreciably disturbing the imagewise distribution thereof, to provide a reversed or positive, colored image of the developed or negative image. The image-receiving element may contain agents adapted to mordant or otherwise fix the dilfused, unoxidized dye developer. Imbibition periods of approximately one minute have been found to give good results with monochrome transfers and from about one to three minutes with multicolor transfers, but this contact period may be adjusted where necessary to compensate for variations in temperat-ure or other conditions. The desired positive image is revealed by stripping the image-receiving layer from the photosensitive element at the end of the imbibition period.

The dye developers may be utilized in the photosensitive element, for example in, on or behind the silver halide emulsion, or they may be utilized in the image-receiving element or in the liquid processing composition. In the preferred embodiment, a coating or layer of the dye developer is placed behind the silver halide emulsion, i.e., on the side of the emulsion adapted to be located most distant from the photographed subject when the emulsion is exposed and preferably also adapted to be most distant from the image-receiving layer when in superposed relationship therewith. Placing the dye developer behind the emulsion layer, as in the preferred embodiment, has the advantage of providing increased contrast in the positive image, and also minimizes any light-filtering action by the colored dye developer. In this preferred embodiment, the layer of dye developer may be applied by using a coating solution containing about 0.5 to 8%, by weight, of the dye developer. Similar concentrations may be used if the dye developer is utilized as a component of the liquid processing composition. In an especially useful mode of disposing the dye developers in the photosensitive elements, the dye developer is dissolved in a waterimmiscible solvent and then dispersed in a gelatin coating solution. 7

It has now been found that when a photosensitive element is processed with a liquid processing composition Containing cesium hydroxide as at least a portion of its alkaline component, a number of unexpected and highly beneficial effects accrue as a result of processing with said cesium hydroxide. Concentrations of cesium hydroxide which have been found to be useful in accordance with this invention fall within the range of about 0.1 to about 25%, by weight, the higher concentrations being used when cesium hydroxide is the sole or principal source of alkalinity.

When photosensitive elements are processed with the novel liquid processing composition of this invention, a marked increase in development rate is noted. This substantial rate increase is apparent when cesium hydroxide is used as the sole alkaline component of the processing composition, as well as when mixtures of sodium hydroxide and cesium hydroxide constitute the alkaline components. f

In addition to an increase in the development rate,the novel cesium hydroxide-containing processing compositions of this invention also provide a significantly shorter development induction period than, for example, a so-.

dium hydroxide processing composition, inprocessing photosensitive elements of the same construction and composition. The term induction period as used herein is understood to pertain to that period of time from the contacting of the processing liquid with the exposed photosensitive element to the start of development of silver halide. In other words, the cesium hydroxide-containing processing compositions of this invention act as more efiicient initiators of development than prior art alkaline materials.

In comparing a dye developer transfer color image formed by processing with the novel cesium hydroxidecontaining processing composition of this invention with an image formed by another alkaline processing composition, a significant increase in the transfer rates of the dyes is noted. This is particularly true of the anthraquinone dyes, particularly a cyan anthraquinone dye. For example, three-color negatives were processed with equimolar aqueous solutions of sodium hydroxide and cesium hydroxide, each with a thickener added. After a 3 minute imbibition with the sodium hydroxide solution, integral densities of 0.33, 1.01, and 1.37 for cyan, magenta and yellow, respectively, were observed, while a negative processed for the same period of time with the cesium hydroxide solution showed integral densities of 1.13, 1.46 and 1.38 for cyan, magenta and yellow, respectively. A monochrome containing a magenta anthraquinone dye developer showed approximately a 10% increase in transfer density when processed with a cesium hydroxide processing composition.

From the foregoing,it can be seen that photographic processing compositions employing cesium hydroxide are of particular interest where it is desired to hasten the diffusion of a dye component of a negative that is located most distant from an image-receiving element superposed on said negative. Dyes locatedin such a position must travel the greatest distance during processing to reach the image-receiving layer, and therefore are often one of the major factors in determining the total necessary processing time. Cesium hydroxide speeds the diffusion of such a dye and particularly an arthraquinone dye.

The resultant increase in efficiency of dye transfer also permits the construction of photosensitive elements using less dye than would be required if the processing were to be carried out with, e.g., a sodium hydroxide processing composition. By this, it is meant that a more efiicient use is made of the initial dye content, with a higher proportion being transferred to give the same transfer density. An appropriate adjustment must be made in the ratio of thedyes in the negative to provide for the differing degrees of increasein diffusion rates of the various dyes.

It has now been found that use of a cesium hydroxidecontaining processing solution makes more practical the use of thinner layers of processing compositions than has been heretofore practical with prior art sodium hydroxide processing compositions. In the past, when an extremely.

has been found desirableto utilize a processing composition comprising, both cesium hydroxide and another 211- kaline material, e.g., sodium hydroxide. By the use of cesium hydroxide as an additive to other alkaline materials, in photographic processing compositions, it is possible to achieve a significant degree, of the above-mentioned advantages provided by cesium hydroxide processing compositions and at the same time minimize the cost by also using sodium hydroxide. In such mixtures, ratios of 0.252% cesium hydroxide and 4.5-7% sodium hydroxide have been found particularly useful. The liquid processing composition within the scope of this invention may also contain, as well as cesium hydroxide alone or cesium hydroxide and sodium hydroxide, a dye developer and, in some instances, it may contain an additional silver halide developing agent. If the liquid processing composition is to be applied to the emulsion by being spread thereon, preferably in a relativelythin, uniform layer, it may also include a viscosity-increasing compound constituting film-forming material of the type which, when spread over a water-absorbent base, will form a relatively firm and relatively stable film. A preferred film-forming-material is a high molecular Weight polymer such as a polymeric, water-soluble ether inert to an alkali solution, as, for example, a hydroxyethyl cellulose or sodium carboxymethyl cellulose. Other filmforming materials'or thickening agents whose ability; to increase viscosity is substantially unaffected when left in solution for a long period of time may also be used.

The liquid processing composition may also contain antifoggants, e.g., befizotriazole, and quaternary ammonium compounds, e.g., N-phenethyl-u-picoliniu-m bromide, N-benzyl-a-picoliniumbromide, as disclosed in the copending application of Milton Greenand Howard G. Rogers, Serial No. 50,851, filed August 22, 1960 (now U.S. Patent No. 3,173,786, issued March 16, 1965).

The novel, processing compositions of this invention were tested in diffusion transfer processes on multilayer photosensitive elements prepared in a manner similar to that disclosed in the above-mentionedUS. Patent No. 2,983,606 and in the copending application of EdwinH. Land and Howard G. Rogers, Serial No. 565,135, filed February 13, 1956, and image-receiving elements comprising polyvinyl alcohol and poly-4-vinylpyridine, such as those disclosed and claimed in the copending application of Howard C. Haas, Serial No. 50,848, filed August 22, 1960, now U.S. Patent No. 3,148,061, issued Sept. 8, 1964. In general, the photosensitive elements comprised a support carrying a red-sensitive silver halide emulsion stratum, a green-sensitive'silver halide emulsion stratum and a blue-sensitive silverhalide emulsion stratum; said emulsions having dispersed in separate gelatin layers behind them, respectively, a cyan dye developer, a magenta dye developer and a yellow dye developer, each pair of emulsion and dye developer.

layers being separated by an interlayer. The particular dye developers employed inthe photosensitive elements were 1) 1,4-bis-[a-methyl-fl-(2',5'-dihydroxyphenyl) ethylamino]-anthraquinone (a cyan dye developer), (2) 2 [p (2',5' dihydroxyphenethyl) phenylazo] 4-isopropoxy-l-naphthol (a magenta dye developer), and (3) 1-phenyl-3-N-n-hexyl-carbamyl 4 [p (hydroquinonyL ethyl) -phenylazo1-5-pyrazolone (a yellow dye developer).

In conducting the tests, areas of photosensitive elements were exposed to blue and green light only, red and blue light only, and red and green light only. The photosensitive elements were then imbibed for 3 minutes in superposed relationship with the aforementioned image-receiving element, using the novel processing compositions of this invention. The integral cyan, magenta and yellow densities were then measured in the various areas of the image-receiving sheet.

The following aqueous processing compositions were used to process the above-described photosensitive elements.

COMPOSITION NO. 1

Percent Cesium hydroxide 22.5 Hydroxyethyl cellulose 4.5

COMPOSITION NO. 2

Cesium hydroxide 18.8 Hydroxyethyl cellulose 4.5

COMPOSITION NO. 3

Cesium hydroxide 17.5 Hydroxyethyl cellulose 4.5

COMPOSITION NO. 4

Cesium hydroxide 22.5

Hydroxyethyl cellulose 4.5 N-phenethyl-a-picolinium bromide 2.0

COMPOSITION NO. 5

Cesium hydroxide 22.5 Hydroxyethyl cellulose 4.5 Benzotriazole 2.0

COMPOSITION NO. 6

Cesium hydroxide 22.5

Hydroxyethyl cellulose 4.5 N-phenethyl-a-picolinium bromide 2.0 Benzotriazole 2.0

The above-described photosensitive elements were also processed with the following sodium hydroxide processing compositions for purposes of comparison.

COMPOSITION NO. 7

The density measurements of photosensitive elements and image-receiving elements processed by the above processing compositions are set forth below in tabular form.

Integral Densities of the Dye Cyan Magenta Yellow Cesium Hydroxide Processing Oompositions:

NoIfi Sodium Hydroxide Processing Compositions:

As stated above, it has also been found desirable to utilize aqueous processing compositions comprising both cesium hydroxide and another alkaline material, e.g., sodium hydroxide. The processing composition set forth below illustrates this embodiment of the invention.

COMPOSITION NO. 14

Sodium hydroxide Cesium hydroxide Hydroxyethyl cellulose Benzotriazole N-benzyl-a-picolinium bromide As previously noted, use of cesium hydroxide-containing processing compositions results in reduced imbibition times and permits the use of thinner layers of the processing composition. These advantages are illustrated by the experiments described below using the above composition 14 and the following composition 15:

COMPOSITION NO. 15

Gm. Sodium hydroxide 5.17 Hydroxyethyl cellulose 4.5 Benzotriazole 2.3 N-benZyl-a-picolinium bromide 2.3 Sodium thiosulfate 1.15

In conducting the tests, areas of photosensitive elements were exposed to (1) blue and green light only, (2) red and blue light only, (3) red and green light only, (4) totally exposed, and (5) no exposure. One photosensitive element was processed with the cesium hydroxide containing composition No. 14 at a gap of 0.0032 in., for 1 /2 minutes. The second photosensitive element was processed with the sodium hydroxide processing composition No. 15 at a gap of 0.0036 in., for 2 minutes. The integral densities in the various areas of the two image-receiving sheets, appearing in tabular form below, were measured by reflectance using red, green and blue filters.

Transfer densities COMPOSITION NO. 14 (1.5 MIN. IMBIBITION) Exposure Red Green Blue Filter Filter Filter Blue and Green 1. 46 0.52 0.43 Red and Blue 0. l2 0. 71 0. 51 Red and Green 0. 08 0. 22 1. 12 Total Exposure 0. 08 0. 14 0. 17 No Exposure 1. 79 2. 04 2. 21

Use of a sodium hydroxide processing composition containing 0.5%, by weight, cesium hydroxide gave a increase in transfer image density when used to process a monochrome negative containing 1,4-diamiuo-2-[ (2',5-dihydroxy) hydrocinnamido amoxy anthraquinone, as compared with the magenta transfer density obtained in the use of substantially the same processing composition except that cesium hydroxide was not present.

In many transfer processes employing dye developers, it is desirable to effect development in the presence of a substantially colorless, auxiliary or accelerating silver halide developing agent, such as phenyl-hydroquinone, toluhydroquinone, 4,4-dimethyl-l-phenyl-3-pyrazolidone, 4-methylphenyl-hydroquinone, etc. This auxiliary developing agent may be present initially in the processing solution, or it may be contained in one or more layers of the negative, e.g., in an interlayer and/ or in an overcoat on the negative.

The novel processing compositions have also been found useful in processing photosensitive elements with the image-receiving elements set forth in the copending application of Edwin H. Land, Serial No. 234,864, filed November 1, 1962, wherein the image-receiving element contains a layer of polymeric acid. The above-mentioned ability to shorten the induction time, increase the rate of diffusion of the dyes and increase the density of the dyes is also noted on the aforementioned image-receiving elements containing a layer of polymeric acid between the image-receiving layer and the support.

The .novel processing composition of this invention may also be used in conventional development processes, black and white as well as color.

It will be understood that cesium hydroxide also may be formed, in situ, as by adding an appropriate cesium salt, e.g., cesium nitrate, to a solution containing, e.g., sodium hydroxide.

Since certain changes may be made in the above prodnet and process Without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description shall be interrupted as illustrative and not in a limiting sense...

What is claimed is:

1. A photographic developing composition comprising an aqueous solution of cesium hydroxide and a quaternary ammonium compound.

2. A product as defined in claim 1 wherein said cesium hydroxide comprises from about 0.1 to 25% by weight of the solution, and said solution contains a silver halide developing agent.

3. A product as defined in claim 1 wherein said developing composition contains a thickening agent.

4. A product as defined in claim 1 wherein said developing composition contains an antifoggant.

5. A process of forming a photographic image in color, comprising developing an exposed silver halide emulsion in the presence of an aqueous alkaline solution comprising cesium hydroxide and at least one dye developer to thereby provide an imagewise distribution of unoxidized dye developer, and transferring at least a part of said imagewise distribution of unoxidized dye developerato an image-receiving layer in superposed relationship with said silver halide emulsion to impart a dye imageto said imagereceiving layer.

6. A process as defined in claim 5 wherein said cesium hydroxide comprises from about 0.1 to 25% by weight of the aqueous alkaline solution.

7. The process as defined in claim 5 wherein said dye developer is disposed, prior to exposure, in the photosensitive element comprising said exposed silver halide emulsion, and the solution containing said dye developer is formed by permeating said photosensitive element with said aqueous alkaline solution.

8. The process as defined in claim 5 wherein said aqueous alkaline solution is introduced by being spread in a substantially uniform layer ,as said photosensitive element and image-receiving layer are brought into superposed relationship.

9. The process as defined in claim 5 wherein said aqueous alkaline solution contains a thickener for increasing viscosity and facilitating the spreading thereof between said photosensitive element and said image-receiving layer.

10. The process as defined in claim 5 wherein said dye developer is an anthraquinone dye developer, whereby the transfer of said anthraquinone dye developer is substantially greater as a result of processing with cesium hydroxide. solution. 7

11. The process as defined in claim 10 wherein said dye developer is 1,4-bis-[rx-methyl-[i-(2',5'-dihydroxyphenyl -ethylamino] -anthraquinone.

12. The process as defined in claim 5 wherein said photosensitive element contains a cyan,a magenta and a yellow dye developer.

13. A process of developing an exposed silver halide emulsion which comprises treating said emulsion with an aqueous alkaline solution comprising cesium hydroxide and at least one dye developer.

14. A process as defined in claim 13 wherein said dye developer is an anthraquinone dye developer.

15. A process as defined in claim 14 wherein said anthraquinone dye developer is 1,4-bis-[a-methyl-B-(2',5'- dihydroxyphenyl) -ethylamino] -anthraquinone.

16. A process as defined in claim 13 wherein said solution contains about 0.1 to 25% cesium hydroxide, by weight.

17. A photographic product for use in a diffusion transfor process comprising a photosensitive element, including a silver halide emulsion, having at least one dye developer in a layer of said photosensitive element, each said dye developer being adapted to form an imagewise distribution of mobile dye developer as a function of development of the silver halide emulsion, an imagereceiving element, and a rupturable container holding an aqueous alkaline processing solution, said aqueous alkaline processing solution including cesium hydroxide, said elements being capable of being superposed, and said container being associated with said elements in such a manner that the container, upon being ruptured, is capable of releasing said processing solution between said superposed elements to permeate said superposed elements, said image-receiving element comprising a support bearing a dyeable image-receiving stratum.

18. A product as defined in claim 17 wherein said photosensitive element contains a cyan, a magenta and a yellow dye developer.

19. A product as defined in claim 17 wherein said aqueous alkaline solution contains a thickening agent.

20. A product as defined in claim 17 wherein said cesium hydroxide comprises about 0.1 to 25% by weight of the aqueous alkaline solution.

21. A product as defined in claim 17 wherein said dye develowr is 1,4-bis-[u-methyl-fi-(2',5'-dihydroxyphenyl)- ethylamino] -anthraquin one.

22. A product as defined in claim 18 wherein said dye developers are 1,4-bis-[u-methyl B (2,5' dihydroxyphenyl) ethylamino] anthraquinone, 2-[p-(2',5'-dihydroxyphenethyl)-5-phenylazo]-4-propoxy-1-naphthol and 10 1-pheny1-3-N-n-hexyl-carbamyl 4 [P-(hydroquinonylethyl) -phenylazo] -5-pyrazolone.

23. A photographic developing composition as defined in claim 1 wherein said solution also contains sodium hydroxide.

No references cited.

NORMAN G. TORCHIN, Primary Examiner.

J. T. BROWN, Assistant Examiner.

Claims (1)

1. 5. A PROCESS OF FORMING A PHOTOGRAPHIC IMAGE IN COLOR, COMPRISING DEVELOPING AN EXPOSED SILVER HALIDE EMULSION IN THE PRESENCE OF AN AQUEOUS ALKALINE SOLUTION COMPRISING CESIUM HYDROXIDE AND AT LEAST ONE DYE DEVELOPER TO THEREBY PROVIDE AN IMAGEWISE DISTRIBUTION OF UNOXIDIZED DYE DEVELOPER, AND TRANSFERRING AT LEAST A PART OF SAID IMAGEWISE DISTRIBUTION OF UNOXIDIZED DYE DEVELOPER TO AN IMAGE-RECEIVING EMULSION TO IMPART A DYE IMAGE TO SAID IMAGESILVER HALIDE EMULSION TO IMPART A DYE IMAGE TO SAID IMAGERECEIVING LAYER.