US2860977A - Photographic foam processing - Google Patents

Description

Nov. 18, 1958 TREGILLUS 77 PHOTOGRAPHIC FOAM PROCESSING Filed Aug. 26. l953 Leonard mfl'egillus INVENTOR.

2,860,97 7 Patented v. 18, 1958 PHOTOGRAPHIC FOAM- PROCESSING Leonard W. Tregillus, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application August 26, 1953, Serial No. 376,733

3 Claims. c1. 96- 61) This invention relates to photographic processes and particularly to a method for processing photographic layers.

In specialized applications of photography employing photosensitive emulsions it is desirable to apply to' the emulsion layer or to any surface associated with the photographic process a minimum" amount of solution required to develop, stabilize; tone, dye or otherwise re'-' act with the photosensitive material or its reaction prod-- proposed for spreading photographic solutions by means: 25

nets in the emulsion layer. Various methodshave been of brushes; sponges or bead applicators. In.each case.

there is the danger of spilling the bulk fluid or applying too muchior too little fluid to the photographic sheet. In many cases, thephotographic sheet is simply immersed in thesolution to avoid the complications of these fluid spreadingmeans but this has the disadvantage with .absorbing materials of undesirably wetting the base or support for the photosensitive layer.

It is therefore an object of the presentinvention to provide' a novelmethod for processing photographic layers. Afurther object is to provide a processing method which does not involve excess wetting of the photographic sup: port. A still further object is to provide a processing method applicable to photographic transfer processes. Other objects willappear from the following description of my invention.

These objects are accomplished, in the broader aspects of my invention, by spreading the processing agent on the photographicsheet as a foam.

Inthe accompanying drawing Fig. l is a perspective view showing a method of applying the foam to a spreading device,

' Fig. 2 is a sectional view showing the manner. in which the spreading device applies the foam to a photosensitive sheet, and c Fig. 3 is a sectional view showing a method of transfer of a foam-developed photographic image to a second sheet.

Foam as used herein means a system consisting of a concentrated dispersion of gas bubbles in-a liquid.. The gas bubbles may be macroscopic, microscopic or ultramicroscopic, whereas the layers of liquid which separate them are of micronic or submicronic dimensions (10 to 5 ma). A foam may therefore be considered as a system of laminae which enclose gas bubbles in the interstices (see Thorpes Dictionary of Applied Chemistry, I. F. Thorpe and M. A. Whitely, Longmans, Green and Company, London, 1941). Inthe foam used for photographic processing according to my invention, the volume of liquid is preferably between 2% and of the foam volume.

The novel feature of my invention is the foam processingof the photographic sheet. The physical structure andstability of the foam may be varied within wide limits to meet the requirements of the particular process and application for which it is. intended. By suitable choice 2. of foaming agents, it is possible to produce foams consisting of large or small bubbles carrying a minimum or maximum of liquid and having a stability from less than a second to several hours or days. With a foam of short life, for example, 3 seconds,it.is possible to spread the foam over the photosensitive sheet and the bubbles break down almost immediately to leave. a uniformflayer of liquid on the sheet. On the other handja stabl'effoam requires some mechanical means of moving the'bubbles on the sheet to insure uniformity of reaction and wetting and also some means either physical or chemicaloffremoving or dispersing the bubbles afterthereaction is complete. With an unstable foam it is generally'neces sary to provide traps to collect the excess liquid from the collapsed bubbles and battles to prevent splattervfrorn reaching parts of the apparatus whichare' intended to be kept dry. A stable foam may be moreeasily contained within the reaction areas but a trap should be provided for reconverting the excess foam back into a liquidf or otherwise disposing ofit. It is to be understood thatmy' invention includes the use of foams of any degree ofstability which may be used to apply. a processinglagent to' a photographic sheet. t c

The production of foams requires that the. parentliquid must possess certain physical' properties such as low surface tension, a high spreading coefficient,.low volatility, etc. A foaming agent, generally surface-active, is usually added to the solution to produce afoam of the required A stability. Solutions for photographic processing in most cases contain fairly high concentrations; of electrolytes some of which may have foaming or anti-foaming prop.- erties. The type offoaming agent to be added is, therefore, dependent on the composition of ,the solution and its pH. Foams of short life may be produced from; certain developing solutions by the addition of lower alkyl.

alcohols, e. g., isopropyl alcohol, nbutyl alcoholyter-y tiary butyl alcohol and isoamyl alcohol. In acid;stabilizing ,baths short life foams may be producedbythe acid itself, e. g., acetic acid. t

For longer-lifed foams; a more highly surface-active agent is required. Cationic detergents, e. g., AerosollB (diisobutyl sodium sulfosuccinate), may beused for solu-' tions of low pH. and anionic detergents,-e.' g., Duponol ME (sodium lauryl sulfate) for solutions ofjhigh pH. Examples of foam-producing non-ionic surface-active agents aresaponin and Onyxol 9162 (a condensed fatty acid alkanolamideLwhichmay beused in acid or alkaline solutions. The choice of a foamingvagent depends onthe specific composition of the solution. In an acid stabilization bath, for example, a short-lifed foam is ob-..

tained due to the presence of acetic acid. The addition' of-O.1% Aerosol IB gives a more stable foamdf the photographic stabilizing agent is thiourea, but not if the stabilizing agent is sodium thiosulfate. Combinations of foaming and anti-foaming agents may be used to obtain. Certain addenda the desired foam life and bubble size. such as glycerine are useful in producing flexible bubble walls. It is the purposeof my,invention to usefoam'for photographic! processing regardless of the particular agentused to producethe foam.

The instability of most foams necessitates that-they be generated immediately before use. In the case of developing solutions, continued exposure of the; thin films'of liquid in the foam to the air would lead to premature of solution poured into the funnel and the air turned on the foam is collected at the top of the funnel. A photographic sheet, emulsion side down, is passed over the top of the funnel to come in contact with the foam. The short time during which the air is in contact with the foambubbles; does not .lead to appreciable oxidation in: the case of. developing solutions. In the case wherethe'gas is stored underjpressure with the solution in ani enclosed container ,a gas compatible with the solution components should be chosen. Dichlorodifluoromethane is satisfac t'ory'providing that an age'ntis present to increaseits solubility in water when under pressure. In some cases the surface-active agent performs this function.

t A particular advantage of the foam processing system is that the means for si ipplying the foam may he andis "posable completely .s'elf-contai'ned unit. Apparatus of this'type' is in use 'commercially for dispensing whipped cream' a nd shaving lather. Ina photographic processing systemthe'foam making cans containing the appropriate s'olutionsmay be attached'to the processing apparatus to supply'foam'fas required, thus eliminating the need for trays or complicated liquid spreading means.

In addition to"providing a foam for photographic processingit is contemplated, by my invention that in the ta'ges of the operation reconversion of the foam to liqui may be accomplished. For example, the bulk of the excess foam is greatly'reduced if reconverted tofa liquid in which state it can be caught in smalltraps. It is to be preferred'btitflnot entirely necessary that the foam attached to the pho' ographicsheet become a liquid in order to achieve "more uniform I spreading.

De foarning may be brought about by physical or "1 chemical means. The suction of the capillary action of blotting} paper-"willcause a foam to collapse with great rapidity, particularly if the normal life of the foam is less than one minute. At the-same time, the blotting paper serves as'an eflicient trap' for the excess liquid from the foam. The removal of a stable foam from the-surface of the photographic sheet may be accomplished by the application of a squeegee or doctor blade, or passage of the 'sheetbetween a pair of wringer rollers. The collapsing o'f;-th'e roam by chemical means may be brought about by=suitablef choice of a foaming agent so that the life of the foam is just sufficient to transport the liquid from the foam generator'to the surface of the photo-sensitive sheet.

Itis po'ss'ible also -to'incorporate in the surface at which defoaming is to'take place certain anti-foaming agents which .will react with the foaming agent in the foam. As an example,a piece 'of blotting paper which has been soaked in %potas'sium chloride solution and dried will cause a quicker collapse of th'efoam than untreated blotting paper,

if the foaming'agenfis Duponol ME, the potassium salt of which is insoluble. I

Apparatus for 'foam processing must provide principally a means of applying the foam to the photosensitive s'urface. Forlaboratory purposes the photographic sheet, emulsion sidedown, was moved over the top of the Biichner funnel with fritted glass disc, from which the foam rwas issuing.- After-allowing a few seconds for development to take place the sheet was squeegeed. If a 'stable foamis used the problem of containment of the foam, is simplified in that there is a minimum tendency for the foam to run. Thephotosensitive sheet may con- I .stitu te the top, bottom or side of the space in which the 'foam is released. Instead of a squeegee, a wringer roller ,may -be 'employed to remove the excess liquid' or foam.

Since only. one side of the photosensitive sheet is wet and only for a short time the sheet is substantially dry after passage through'the wringer.

, Anelementary system for developing and processing a sheet of silver halide photosensitive paper with a stable foam is shown in Figures 1 and 2 of the accompanying drawing. As shown therein, a spreading device, consisting of a doctor blade 10 set at an acute angle and two side members 11, serving to hold the doctor blade 10 at its predetermined angle, is first sprayed as in Figure 1, while in tainer 12. The spreading device, in an upright position,,

an exposed photosensitive layer 14, sheet 13 resting on a; sheet of blotting paper 15 for the purpose of absorbmg,

an inverted position, with foam from a pressurized con-J is set down, as in Figure 2, on a sheet 13 having thereon excess foam. On setting the spreading device down on the photosensitive sheet 13, the doctor blade 10 presses the foam laterally over the photosensitive layer 14 to the. limits established by the side members 11. The spreading device is moved over the photosensitive layer 14, with the edge of the doctor blade 10 going last and removing: substantially all of the excess surface foam 16. The acute angle at which the doctor blade 10 is set serves to slide the foam 16 over the photosensitive surface 14 to insure uniform development, .The energy of the developing.v agents in the foam and the size and speed of movement of the spreading device are adjusted so that development of the image 17 is essentially complete while the photosensi- M J tive layer 14 is under the doctor blade 10. After the 1 f foam is spread on the photosensitive layer 14, the sheet 13 is inverted and blotted on sheet 15 to remove any foam] which may have slipped out from under the spreading device.

ifs'repeated. This completes the processing.

containing processing agents.

' Foam processing is also especially suited to the method described in Yutzy and Yackel U. S. Patent 2,740,717, in which the negative developer is contained within the nega-. F

tive' emulsion and is non-wandering and the receiving sheet contains compounds which precipitate the silver' i complex ions diffusing from the negative sheet without the aid of a developing agent, thereby eliminating the problem.

. of receiving sheet stain.

- technique of foam procesisng is useful in many other systerns; for example, a foam processing agent may be applied to a sensitive material described in Yutzyand Yackel The method of processing a material of the solvent transfer type is illustrated by the sectional view of Fig. 3 Asshown therein, a sheet of paper or other suitable flexiaq ble support 18 has thereon a silver halide emulsion layer" 19 which may or may not contain a developing agent."

This layer is exposed in the usual way and a foam of processing agent 20 'is then applied to it and spread over' i the photosensitive surface in any suitable manner. The} sheet carrying the foam is then placed in contact with a receiving sheet 21 and the sandwich is passed between wringer rollers 22 which press the two sheets together.

After remaining in contact for about a minute the sheets are stripped apart and a positive image is found onthe',

transfer sheet 21.

As illustrated in Fig. 3, it is necessary in some systems that the receiving sheet 21 be water-proof in order that the sandwich does not become too dry during the course of the transfer operation owing to the absorption of liquid by the paper base of sheet 21. If receiving sheet 21 is,

for example, baryta paper and not water-proofed, then application'of a foam of processing agent 20 to both." sheets 18 and 21 willsupply enough moisture for'th'e' transfer operation.

' In addition to theapplications referred to' abovethe U. S. Patent 2,596,756, May 13, 1952, in which unhardened portions of gelatin are transferred from a sensitive 7 layer to a receiving sheet in a document copying process.

A further use of foam processing is in aerial protorecon-'- j I naissance, where it is desirable to process ordinary films v A second foam containing stabilizing agent is dispensed on a" second spreading device from a second pressurized can and the spreading and blotting process befdrethe aircraftjhas returned to its base. Rapid processing of motion picture films for televisionv may be speeded up with reduction inthe amount of apparatus required because ofthe minimum amount. of solution applied to the film and the consequent reduction in swelling of gelatin. In the processing'of duplitized motion picture .film a: foam. can .be .used. easily. to apply solution .to only one side ofthe film. at a time. Foam solutionsmay be ifcompoundedutodevelop,. bleach, dye, tone or clear the. film .asurequired. Similarly, foam application to a multilayercolonfilmmay.be.employed to restrain reaction tozthe. outermostlayerwhere desired. Facsimile reproduction can be simplified .with foam processing.

Foam processing .techniques may be .used with'v photographic processes .othenthan those based on silver halide sensitivity. Reproduction processes employing diazoniurn compounds maybe simplified by applying the coupling solutions as-afoarn. Development by foam may be applied also to systems based on the photosensitivity of iron salts.

Examples of foam processing follow, it being understood that these are merely illustrative and that the invention is not limited to the materials, proportions, apparatus or manipulations set forth therein.

Example 1 A sheet of thin coated gelatino-silver chloride paper was exposed to a line image and was then drawn over the top of a foam generator, the foam being produced from 10 cc. of developing solution in a 50 cc. funnel with a fritted glass plate, air being supplied through the stem by means of a hose connected to an air compressor, with a needle valve control. In order to make up the final developing solution, a developing solution was first made up as follows:

Grams N-methyl-p-aminophenol sulfate 3.1 Hydroquinone 12 Sodium sulfite, desiccated 45 Sodium carbonate, monohydrate 80 Potassium bromide 1.9

Water to 1 liter.

Thiourea 10% solution cc 10 Acetic acid cc 0.5 Saponin g 0.0004

After 10 seconds the excess solution was removed with a squeegee. The image area had good black tones and the non-image areas were resistant to print-out upon exposure to a No. 2 Photofiood lamp for one minute at two inches.

Example 2 A sheet of thin-coated gelatino-silver chloride paper was exposed to a line image and processed with a developer and a stabilizer in the manner illustrated by Figures 1 and 2. In order to make up the final developing solution, a developing solution was first made up as follows:

Water cc 200 Sodium sulfite, desiccated grams l Hydroquinone do 4 Sodium hydroxide do 3.2 Potassium bromide do 0.4 l-phenyl-3-pyrazolidone -do 0.4 Onyx-o1 9162 (condensed fatty acid alkanolamide) cc 8.0

To 50 cc. of this developing solution, in'the pressurized" container chilled in a Dry Ice-acetone bath, there was added 10 cc. of liquid dichlorodifiuoromethane; after capping, the container was warmed to room temperature for use. p

In a similar manner, a stabilizing solution was prepared as follows: V

Water 1 cc Thiourea grams' 10 Acetic acid cc 15 Onyxo19162 cc 2 A second pressurized container was filled with 50 cc. of this solution and 6 cc. of liquid dichlorodifluoromethane.

The foam of the developing solution was dispensed on the spreading device from which itwa's transferred to the photosensitive paper. After blotting,- the photosensitjive paper had applied 'to it a foam of the stabilizing solution in a similar manner.

Example 4 This example illustrates foam processing in a solvent transfer process.

A receiving sheet was first prepared in a manner similar to that disclosed by E. H. Land in U. S. Patent No. 2,635,048 by rubbing baryta paper with a mixture consisting of:

Silica (Linde) grams 30 1% sodium sulfide cc 280 Cadmium acetate grams 3 1% lead acetate cc 1 Water cc 20 The sheet was squeegeed and dried before use.

A negative-speed gelatino-silver bromoiodide emulsion was exposed to a continuous tone image and was developed by foam application in the manner described in Example 1 with a developer consisting of:

Hydroquinone gram 0.35 Sodium sulfite, desiccated do 0.89 Sodium thiosulfate do' 0.15 Sodium hydroxide do 0.28 Potassium bromide do 0.025 Benzotriazole 0.5% solution cc 0.25 Isopropyl alcohol cc 0.1 Water cc 10 Immediately afterwards the foam was applied to the receiving sheet. The negative sheet and the receiving sheet were placed in contact face-to-faee and passed between a pair of rollers. After one minute the sheets were separated and a positive image of good characteristics was obtained on the receiving sheet.

It will be understood that the examples and modifications described herein are illustrative only, and that my invention is to be taken as limited only by the scope of the appended claims.

What I claim is:

1. The method of forming a visible image in an exposed gelatino-silver halide emulsion layer, which comprises spreading on said exposed layer a foam consisting of a concentrated dispersion of gas bubbles in a liquid the volume of liquid being between 2% and 30% of the foam volume, said foam containing an aqueous solution of an anionic surface active agent and at least hydroquinone as a developing agent, allowing said foam to remain in contact with said layer for about 5 seconds, removing the excess foam from said layer, spreading on said layer a stabilizing foam of thiourea and a surface-active agent which creates a stable physical foam for an appreciable period of time, allowing said stabilizing foam to remain in contact with said layer for about 10 seconds, and then removing the excess stabilizing foam from said layer.

2. The method of forming a visible image in an exposed gelatino-silver halide emulsion layer, which comprises spreading on saidrexposed layer a foam consisting of a concentrated dispersion of gas bubbles in a liquid, the volume of liquid being between 2% and 30% of the foam volume, said foam containing an aqueous solution of approximately 1.2%, hydroquinone, approximately 3%, N-methyl-p-aminophenol sulfate, approximately 4.5%, sodium sulfite and .01 to .1% sodium lauryl sulfate, allowing said foam to remain in contact with said layer for about 5 seconds, removing the excess foarnfrom saidlayen spreading onsaid layer astabilizing foam comvolume, said foam containing thiourea and a.surface active agent which creates a stable physical foam for a appreciable period of time. ,v I 5 References Citedin the file of this patent v UNITED STATES PATENTS 1,751,881 Pifer l. M281; 25'; 1930 2,000,353 Schaeffer May '7,-19'35 0 2,178;450 Jaegeret al Oct. 31, 1 939 1 2,333,821 Salo et'al Nov. 9,194; 2,375,007 Larsen -4 May 1, 1945- 12,453,346 Russell Now-9,1948 2,578,075 Kienast Dec.1l, 195-li v 2,644,756 Land July .7, 1953 Y 15 2,655,480." 1 Spitzer et a1; Oct.13, -1 953;

FOREIGN PATENTS" 4,689

' Great Britain of 1 8 94;

Claims (1)

1. THE METHOD OF FORMING A VISIBLE IMAGE IN AN EXPOSED GELATINO-SILVER HALIDE EMULSION LAYER, WHICH COMPRISES SPREDING ON SAID EXPOSED LAYER A FOAM CONSISTING OF A CONCENTRATED DISPERSION OF GAS BUBBLES IN A LIQUID THE VOLUME SAID FOAM CONTAINING AN AQUEOUS SOLUTION FOAM VOLUME, SAID FOAM CONTAINING AN AQUEOUS SOLUTION OF AN ANIONIC SURFACE-ACTIVE AGENT AND AT LEAST HYDROQUINONE AS A DEVELOPING AGENG, ALLOWING SAID FOAM TO REMAIN IN CONTACT WITH SAID LAYER FOR ABOUT 5 SECONDS, REMOVING THE EXCESS FOAM FROM SAID LAYER, SPREDING ON SAID LAYER A STABILIZING FOAM OF THIQUREA AND A SURFACE-ACTIVE AGENT WHICH CREATES A STABLE PHYSICAL FOAM FOR AN APPRECIABLE PERIOD OF TIME, ALLOWING SAID STABLILZING FOAM TO REMAIN IN CONTACT WITH SAID LAYER FOR ABOUT 10 SECONDS, AND THEN REMOVING THE EXCESS STABILIZING FOAM FROM SAID LAYER.

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