Патент USA US2403428код для вставки
July 2, 1946. F. w. H. MUELLER EI'AL } 2,403,423 INTENSIFIGATION OF THE LATENT IMAGE Filed Sept. 50, 1942 2 Sheets-Sheet l 722,0ed 7b Blower Outlet Acz'a’ Jodi-ed INVENTORS Fritz I44 Hellmut Mueller ' . BY James E Bates AT ORNEY. July 2; 1946. F. w. H. MUELLER EI'AL 7 2,403,428 INTENSIFICATION OF THE LATENT IMAGE Filed Sept. 50, 1942 . > 2 Sheets-Sheet 2 'Ki \k’ _. N m x \> -- ‘‘ ‘ N‘ ‘$1 ' E -- K $ x Q‘ Q: ‘Q g b Q K $3 -- Q8 ‘g -- 3 Q §‘Q Q . \“ % M Y ?g \ '\> E’ ? ‘ ‘1 CD [229x55 I . INVENTORS Fritz ///./ l/ellmuZ Mueller By James 15 Eates A TTORNEY I Patented July 2,v 1946 2,403,428 UNITED STATES‘ PATENT OFFICE‘; 2,403,428 _ INTENSIFICATION OF THE LATENT IMAGE Fritz W. Hellmut Mueller and James E. Bates, Binghamton, N. Y., asslgnors/to General Aniline & Film Corporation, New York, N. Y., a corpo ration of Delaware Application September 80, 1942, Serial No. 460,196 10 Claims. (Cl. 9546) ' 2 1 The present invention relates to a new photo graphic process and more particularly to a meth 0d of intensifying or hyper-sensitizing exposed photographic emulsions. The purpose of _such intensi?cation is to increase the effective sensi tivity of a photographic emulsion or a photo culiar disadvantage that the increase in e?‘ec-‘ tive speed produced by such treatments is rather small when applied to high-speed emulsion ?lms while the greater speed increases are obtained only with the low speed emulsion ?lms. Such known methods are also cumbersome or involve the use of expensive apparatus and unstable In the art of photography it is often desirable chemical compounds or solutions. It is, there to increase the effective speed of photographic fore, an object of the present invention to pro emulsions as much as possible. This is partic 10 vide a simple method for treating photographic ularly so when exposure must be made under emulsions whereby the quality and speed of the marginal light conditions. Intensifying the la photographic emulsions and particularly medium tent image obtained by exposure of a light sen and high-speed ‘photographic emulsions are im sitive silver halide emulsion under marginal light proved to such a degree that the sensitivity of conditions permits the photographer to obtain a 15 the emulsion is increased far beyond its original fully graduated, shadow-detailed and well de?ned value. It is a further object to provide a sim picture where otherwise the quality of the neg ple method of obtaining photographic records ative would be poor because of under-exposure. under extremely limited light conditions which In motion picture photography where very in would not produce a sufficiently developable la tense illumination is employed, the cost of such 20 tent image on the high-speed commercially avail illumination can be materially reduced ,and the able ?lms to permit of obtaining proper photo graphic element. _ - working conditions, rendered disagreeable by the amount of illumination required, ‘can be materiq graphic recording under ordinary conditions of development. It is still another object of this invention to provide a method of intensi?cation 25 of the latent image which does not necessitate ally improved by the use of a process ‘for inten si?cation of thelatent image. The results ob tainable by press and aerial night photographers the use of materials di?cult' to handle or un working under conditions where the lighting is stable under ordinary conditions. 4 limited can also be greatly improved by intensi In the accomplishment of these andother ob ?cation of the latent image after exposure. jects according to this invention, it has been dis Various methods for intensifying the latent im 30 covered that the latent image produced on a age-have beendescribed. In U. S. P. No. 2,168,971, > photographic element by exposure can be inten issued August 8, 1939, there is described a meth . si?ed by treatment of the exposed and undevel od of increasing the speed of photographic emul oped material with the vapors of organic acids sions by submitting exposed and undeveloped or solutions of organic acids in suitable solvents. ?lms to an atmosphere having a relative humid 35 This method gives substantial increases in the ity of about 80% ‘and a temperature of 120° F. for a predetermined length of time. U. S. P. No. case of lowv and medium speed emulsions and yields outstanding results in they case of high speed emulsions. The e?ect of the intensi?ca tion achieved by this method in the case of the 2,201,591, issued May 21, 1940, achieves a similar I eilect by pro-bathing the exposed and undevel oped ?lm in activating solutions, the activating 40 highest speed emulsion is to increase the sensi agents of which are meta substituted amino and tivity by 400% of its original value without pro hydroxy derivatives of benzene such as resorcinol ducing objectionable fog or any noticeable in or meta. nitraniline. According to U. S. P. No.’ 2,146,802, issued February 14, 1939, the'effective crease in the grain size of the silver halide. It is, therefore, possible to obtain pictures'possess speed of photographic emulsions ‘before and after 45 ing a de?nition of detail and brilliance not here exposure may be increased by treatment with tofore obtainable with any known photographic mercury vapor. G. S. Moore, in the Photo ‘material when making the exposure under ex graphic Journal, volume 81, pages 27-32 (1941), refers to exposure of the latent image to green light and in U. S. P. No. 2,220,882, issued Novem ber 12, 1940, ?ashing of the latent image with tremely poor light conditions and developing the ?lm by known methods. In principle, this proc . ess of intensi?cation is carried out as follows: The exposed and undeveloped ?lm which may be either black and white or color ?lm, hard ened or non-hardened, sensitized or unsensitized, For the most part these prior art processes for is exposed to an atmosphere of organic acids in a intensi?cation of the latent image have the pe 55 vapor state containing at least traces of water infrared radiation is suggested for the same pur 2,408,428 3 sisting of ‘75% C. P. glacial acetic acid and 25% C. P. formic acid. The cabinet was closed and the fan put in operation. The conditioning with rachloride which alcohol or non-polar solvent contains at least traces of water but not more than 1% by volume. By “traces 01’ water” we the acid vapor occurred at an average room tem perature of 70° F. and an average relative humid ity of 50%. After 10 minutes’ treatment, the ma mean to include amounts of water which are. for instance, as low as two parts or water per mil lion. . The treatment is carried out at room tem perature or slightly elevated temperatures, pref 4 dish was charged with 25 cos. 0! a mixture con vapor or is immersed in a bath consisting of a solution of an organic acid in an alcohol or'a non-polar solvent such as benzene or carbon tet terial was developed at 68° F. in a metol hydro quinone developer for 14 minutes. A suitable 10 metol hydroquinone developer is one of the fol- lowing composition diluted 1:1 (one part devel oper and one part water). , atmospheric conditions or in vacuo. Increases in the speed of the emulsion of some 50% to 400% Hot water (125° F.) ________________ __cc__. 750 have been observed and in contrast to known Metol _________________________ __grams__ 1.5 methods 01' intensi?cation, the high-speed emul 15 Sodium sul?te, anhyd ____________ __do____ 45 sions show the greatest response to the treat Sodium bisulfite ________________ __do____ 1 ,ment; that is, a greater increase in the sensitiv Hydroquinone __________________ --do____ 3 ity or high-speed emulsions is achieved than in Sodium carbonate, monohydrated___do____ 6 erably not higher tha 85° to 90° F. under normal _ the low and medium speed emulsions. _ In carrying out the process by treatment of 20 the exposed ?lm with the acid vapors .any con venient enclosure, which will con?ne the vapors and permit of intimate contact of all parts of the Potassium bromide_._-___; ________ __do____ Water to make _________________ "liters" 0.8 1 The effective speed of the ?lm was tripled with out appreciable increase in fog in comparison with an untreated ?lm exposed and developed emulsion surface of the ?lm with the acid va pors, may be employed. For cut ?lm a wooden 25 under identical conditions. cabinet 12" x 21" x 34" has been found suit Example 2 able. This will hold a number of ?lm strips which can be treated simultaneously. An electric "Triple’S” Pan Portrait ?lm was exposed and fan should be provided therein to give even cir treated as above for 20 minutes. The e?‘ective culation of the vapors rising from an open dish 30 speed was doubled in comparison with untreated of the acid. With such an arrangement the ?lm exposed and developed under identical con treatment requires from 10 minutes to 11/2 hours, ditions. depending upon the type and concentration of Example 3 the acid. While all organic acids which possess Exposed SS Pan Aerial ?lm was placed for 6 a su?lciently high vapor pressure at temperatures 35 minutes in a solution of commercial benzene con which are not detrimental to the photographic taining %% by volume of acetic acid and 1/r% materials may be used, it has been found prac by volume of formic acid at ‘72° F. Agitation was tical in order to cut down the time of the treat provided for 5 seconds every 2 minutes. After ment to use lower molecular weight, aliphatic acids and particularly formic acid, acetic acid, 40 removal of the ?lm from this solution and evapo propionic acid or isobutyric acid; Mixtures of ration of the benzene, the film was tank-devel oped at 68° F. for 15 minutes in a metol X-ray formic acid and acetic acid have in some in ?lm developer of the following composition: stances been found to give more rapid results than acetic acid alone and the selection of a suit Hot water (125° F.) __________________ __cc 750 able ratio between the formic and acetic acids 45 Metol _____________________ __.___grams__ 3.5 enables the operator to choose the more conven Sodi m sul?te, anhyd ___________ __do____ 60 ient length of time for the treatment. A par Hyd oquinone __________________ __do____ 9 ticularly advantageous container for carrying out Sodium carbonate, monohydrated __do____ 40 the vapor treatment is the so-called Smith de Potassium bromide ______________ __do_-__ 2 veloping machine modi?ed to allow for acid va 50 Water to make _________________ __liters__"‘ 1 porization and circulation. This device is illus The effective speed of the ?lm was tripled in trated in the drawings wherein Figure I is a per comparison with untreated ?lm exposed and de-' spective view of the top and core of the Smith veloped under identical conditions. _ developing machine and Figure II is a perspec tive view of the can or container for the core of 55 Example 4 Figure I. The legends on these’ ?gures adequate ly explain the elements which have been added Exposed “Triple S” Pan Aerial ?lm was placed to the regular Smith developing machine to for 32 minutes in a solution of commercial car adapt it to this use. When the acid treatment bontetrachloride, containing %% by volume of is carried out by bathing the ?lm in, for instance, 60 acetic acid and 1A% by volume of formic acid at a benzene solution of the organic acid, the solu 72° F. Agitation was provided for 5 seconds ev tion should be placed in a tank provided with ery 4 minutes. The ?lm was developed at 68° F. agitating means to provide for circulation of the for 15 minutes in a metol X-ray ?lm developer of acid solution in contact with the ?lm. the following composition: The following examples will serve to speci?s 65. Hot water (125° F.) ________________ __cc__ ‘750 cally describe the process as applied to particu Metol ________________________ __grams__ 3.5 lar types of ?lms. They should not be construed Sodium sul?te, anhyd ___________ __do____ 60 as limiting or restricting this invention to the use Hydroquinone __________________ __do____ 9 of any of the containers or speci?c conditions mentioned therein, but shall be considered as il 70 Sodium carbonate, monohydrated__do____ 40 lustrative. - Example 1 SS Pan Aerial ?lm was exposed and placed in a wooden conditioning chamber (12" x 21" x 24") Potassium bromide ______________ __do____ 2 Water to make ____ __- ___________ __liters__ 1 The effective speed after the treatment was 11/2 that of an untreated ?lm exposed and de equipped with a small electric fan. A 4"-Petri 75 veloped under identical conditions. 2,403,42a 5 6 Example 5 it is necessary to give the absorbed acid an opportunity to exert its speed increasing in?u SS Pan Aerial ?lm was treated for 10 minutes in a Smith developing machine modi?ed as ence upon the latent image after exposure. It development takes place too soon after exposure of a ?lm which has 'been pretreated .with the shown in the drawings discussed above. The apparatus was prepared for the treatment by placing a solution of 2 parts of glacial acetic acid and 8 parts of formic acid on absorbing or acid, desensitization invariably occurs since there has been no opportunity for the acid to act on the latent image. Development of a ?lm so treated, therefore, should be delayed for several blotter paper shown attached to a side wall of the can. The cover ?tting over the winding after exposure. Although this alternative knobs and motor supports was taped tightly over 10 hours procedure is of advantage where it is not the can top during the treatment. Air was blown into the can to circulate the acid vapors - > possible to condition the already exposed ?lm by treatment with the organic acid vapors, the pre around‘the ?lm through the rubber inlet tube taped to the blower outlet. This air circulates past the acid-soaked blotter where it becomes ferred practice is to submit the photographic material after exposure to the treatment with the acid vapors. In either case it will be apparent » saturated with acid vapors. The humidity of the that the latent image produced by exposure of air itself supplies the necessary water content for the photographic material is acted upon by the the vapor mixture. It then circulates around the acid vapors in the presence of moisture. Simi ?lm as the latter is run from spool to spool and is carried. out of the tank or can through the 20 lar considerations apply to the treatment of the photographic elements containing latent images exhaust tube. 15 cc. of the acid mixture was in solutions of the organic acids. Thus the ?lm may be treated prior to exposure in a solution of the organic acid in a suitable solvent. su?icient for this treatment. The reels and ?lm were removed and placed in another tank containing a developer of the following com position: It has-‘been found that the solution methods . are more suitable for out ?lm or short lengths of roll ?lm and, although any solvent which will dissolve the organic acid with at least traces of water is suitable for the solution treatment, methanol and ethenol and such non-polar sol Hot water (125° F.) _____________ __cc____ 750 Metol _________________________ "grams" Sodium sul?te, anhyd ___________ __do____ 3.5 60 Hydroquinone ___________________ __do____ 9 Sodium carbonate, monohydrated__do____ 40 vents as benzene and carbontetrachloride have Potassium bromide ______________ __do____ Water to make _________________ "liters-" 2 1 been found most suitable. It is interesting to note that whilepre-bathing of an exposed pho tographic element containing a latent image in Development was carried out in the usual Way at 72° F. for 10 to 12 minutes. The eifective speed of this ?lm was three times that of un treated ?lm exposed and developed under identical conditions. ' The conditions of the vapor treatment may be varied and advantageously adapted according to dilute aqueous solutions of organic acids such as acetic acid does not produce intensi?cation of the latent image and may lead to desensitiz ing if the acid concentration increases, neverthe less, pre-bathing in alcohol such as methanol and 40 ethenol containing up to 10% acetic acid or an the speci?c results desired. The speed of acid vapor intensi?cation of the latent image can also be increased some ?ve times by carrying out the process in vacuo. Also, formic acid reacts on the latent image about ?ve times as rapidly as acetic acid and higher concentrations of either acid permit of shortening the time of the treatment as does also more rapid circulation of the vapor or increase of the temperature above room tem acetic-formic acid mixture produces a substantial intensi?cation of the latent image. The water content of such an alcohol acid bath preferably should not be more than 1% by volume. Obvi ously. alcoholic bathing solutions can best be practiced in accordance with the process of this invention where the light-sensitive layer‘to be treated rests upon a support which is not readily attacked by that type of solvent. In. the case of perature to approximately 85° to 90° F. The 50 non-polar solvent such as benzene or carbontetra chloride which are not miscible with water in any process is not limited to any particular type of appreciable proportions the water necessary for emulsion but is applicable to emulsions sensi the process may be provided by the natural im tized for any region of the spectral range, such purities of the solvents. A water content of, for as ortho, panchromatic and infrared emulsions. instance, 0.0002% in benzene containing 1% Simple experimental tests will establish the acetic acid will give the intensi?cation of the la optimum treatment for each particular type of tent image as described in Example 3. ( The per ?lm. In general, shorter treatments produce less centages given are by volume.) Immersion times intensi?cation, but an insu?iciently hardened for the liquid method treatment range from 5 to emulsion may soften excessively under a more. extended treatment. Also, the acid which the 60 30 minutes for optimum effects. The solvent absorb-ed by the ?lm during immersion should ?lm absorbs in the conditioning chamber con be removed from the ?lm before development tinues to react after removing the ?lm from the chamber until it has evaporated or becomes neu tralized by the developer. Consequently, if a ?lm has received optimum conditioning in the chamber there should be no delay in the develop ment. Otherwise, over-treatment _will result. Conversely, a less than optimum treatment may be corrected by withholding development for a few hours. This same effect permits‘of submit ting the ?lm before exposure to the organic acid vapor treatment and employing the acid absorbed by the ?lm during such treatment for ‘intensi?cation of‘ the latent image after exposure. In following such a procedure as this, 75 since such solvents as benzene and carbontetra chloride are immiscible with the usual devel opers. This removal of the solvent after the acid treatment can be effected by evaporation or rins ing in an ethenol bath, care being taken in the latter case to keep the rinsing time short enough not to alfyect the ?lm base. In all of the liquid methods or immersion treatments, vigorous agi tation of the acid solution is desirable and the temperature of the bath can be raised to ap proximately 85° to 90° F. in order to speed up . the action. As further examples of the results which 'are ' 2,403,428 _ 8 7 polar solvents containing up to 1% of water and developing the latent image. obtainable by this process, the following speed in . creases are typical: “Ansco” Ultra Speed Pan, Su persensitive Pan Aerial and Infrared emulsions can be made 3 to 4 times faster‘; cine negative 2. The process of intensifying the latent image of an exposed photographic silver halide emul “Supreme,” “Triple S” Pan and “Triple S” Ortho sion which comprises introducing the exposed emulsion prior to development into an atmos phere of organic acid vapors containing at least traces of water vapor, removing it therefrom, and when developed in developers conventionally used developing the latent image. for those ?lms. In cases where extreme speed 3. The process or intensifying the latent image and contrast are of primary importance and a 10 of an exposed photographic silver halide emul slight increase in graininess and fog less essen sion which comprises immersing the exposed ' tial, the use of more energetic developers, for emulsion prior to development in a bath con instance those of the X-ray type, will produce sisting of a solution of an organic acid in a maximum speed. Increases obtained by the acid vapor treatment were evidenced in most cases 15 volatile non-polar solvent containing such amounts of water as are miscible with the sol by an extension of the threshold sensitivity, but vent, removing the emulsion from the bath, evap gave a material increase of all the densities up orating the solvent and developing‘the latent im to approximately 1.0 or 1.2. At this point the age. increase became relatively smaller, until at the v4. The process of intensifying the latent image shoulder region either no increase or a slight de of an exposed photographic silver halide emul crease of density resulted. Such extension of the sion which comprises immersing the exposed toe produced an overall ?attening of the grada emulsion prior to development in a bath consist tion, but for miniature camera work where low ingiof a volatile- alcohol solution of an organic density negatives are customary this ?attening is not a disadvantage. The flattening of the 25 acid containing up to 1% of water, removing the cut ?lm can be doubled in speed; Finopan and “Fluorapid” film can be made 11/2 times as fast emulsion from the bath, evaporating the solvent > gradation may also, if desired, be counteracted by a slight extension of the developing time. Figure and developing the latent image. 5. The process of treating an exposed photo-t graphic silver halide emulsion containing a latent III of the accompanying drawings, illustrates typ ical speed increases obtained by the organic acid treatment. In said Figure III, wherein the ordi 30 image which comprises contacting said exposed emulsion prior to development with an organic nates represent densities and the abscissae rep acid vapor ‘containing at least traces of water resent the log of exposure. “A” is the density curve for “Ansco” Ultraspced Pan ?lm which has vapor for at least 10 minutes at a temperature been exposed and developed in the ordinary of‘ from room temperature to 90° F. and develop manner, “B” is the density curve for the same 35 ing the latent image. 6. The process of treating an exposed photo type of ?lm exposed under the same conditions graphic silver halide emulsion containing a latent and treated with acetic acid vapor prior to de velopment in accordance with the method of the present invention. A similar curve is obtained by treating the exposed film with a solution of image which comprises contacting said exposed emulsion with an organic acid vapor containing at least traces of water vapor for from 10 min utes to 11/2 hours while circulating the said va pors in contact with the emulsion at a tempera ture of from room temperature to 90° F. and acetic acid in benzene containing water as an im purity of the solvent. _ ' In .contrast to other known methods for in tensi?cation of the latent image the increase in 45 developing the latent image. 7. The process of claim 6 wherein the organic sensitivity obtained by the acid vapor treatment acid vapor is a mixture of acetic and formic acid of this invention is quite permanent. In fact, if vapors. ~ development is somewhat delayed after treat 8. The process of intensifying the latent image ment, the increase in sensitivity progresses for several days, then does not noticeably change for 50 of an exposed photographic silver halide emul two or three weeks. sion which comprises immersing the exposed After four to seven weeks’ emulsion prior to development in a bath con storage the increase will be reduced only to ap sisting of a 1% solution of an organic acid in proximately %2 its original value and the increased benzene containing at least traces of water at a sensitivity will not be completely lost until it has been stored for approximately 10 months. The 55 temperature of from room temperature to 90° F. and removing the emulsion from the bath, increased sensitivity of ?lms submitted to other evaporating the benzene and developing the la known methods of intensi?cation in some in tent image. stances begins to diminish shortly after the 9. The process of claim 8 wherein the organic treatment and in most cases has been completely lost in a few weeks’ time. ‘ Having thus described our invention, what we 60 acid is a mixture of acetic-and formic acids. 10. The process of intensifying the latent im claim as new and desire to secure by Letters. Pat age of an‘ exposed photographic silver halide cut is: emulsion which comprises immersing the exposed . ' ‘ v emulsion prior to development in a bath consist 1. The process of intensifying the latent image of an exposed photographic silver halide emulsion 65 ing of a 10% acetic acid methanol solution con taining not more than 1% water, removing the which comprises contacting the exposed emul emulsion from the bath, evaporating the meth sions prior to development with a member of the anol and developing the latent image. group consisting of organic acid vapors contain _ ' FRITZ W. HELLMUT MUELLER. ing at least traces of water and solutions of or, JAMES E. BATES. ganic acids in volatile alcohols and volatile non 70 .