US2113329A

US2113329A - Color photography

Info

Publication number: US2113329A
Application number: US8516A
Authority: US
Inventors: Leopold D Mannes; Jr Leopold Godowsky
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1934-06-15
Filing date: 1935-02-27
Publication date: 1938-04-05
Anticipated expiration: 1955-04-05
Also published as: DE723388C; NL44563C; DE721610C; BE412165A; FR791320A; BE409947A; GB447092A; FR802755A; FR791319A; NL44564C; FR797400A; GB440032A; NL44565C; BE409946A

Description

April 5, 1938.

L: D. MANNE-S ET AL coLoR PHOTOGRAPHY Filed Feb. 27, 1935 SENSITIVE EMULS/0N LAYER (YELLOW) NERT LAYER CONTA/NIN@ YELLOIJ DYE SENSITIVE EMULS/ON LAYERMAGENTA) SENSITIVE EMULS/ON LAYER BLUE 'GREENI LA TENTBLUE IMAGE gvwmtom Lefoulzummw duomwc -Patented Apr. 5, 1938 COLOR PHOTOGRAPHY Leopold D. Mannes and Leopold Godowsky, Jr.,

Rochester, N. Y., assignors, by mesne assignments, to Eastman Kodak Company, Jersey City, N. J., a corporation of New Jersey Application February 27, 1935, Serial No. 8,516

19 Claims.

'I'his invention relates to color photography and more particularly to a process in which a plurality of light-sensitive layers are treated to form a colored photographic record.

This application is a continuation-in-part of our application, Serial Number 634,182, filed September 21, 1932, matured into U. S. Patent No. 2,059,884, of November 3, 1936. i

It is known in. processes for producing colored l0 photographs in which a plurality of layers of differently sensitized emulsions are treated to produce a colored photographic record by simultaneously exposing the. layers, and then developing, fixing and coloring the resulting images in various ways. It has been proposed to dye the sensitired emulsion layer prior to exposure and later to remove the dye at the image or non-image portions. Processes have also been devised in which a dye-forming compound is mixed with the emulsion layer and a dye formed upon development. These processes all have numerous objectionable features, among which are the difficulties in processing and the inability of the` user to obtain satisfactory colors.

An object of the present invention is to produce a satisfactorily colored photograph in two or more colors by simple and practical procedure. A further object is to produce a film adapted for taking pictures in' three colors in which no color- A ing matter or color-forming substances is mixed with the emulsion prior to exposure. Other objects and advantages will'be apparent from the following description.

'I'hese objects are accomplished by' the following invention in which the colors are formed by a chemical coupling or dye formation, a dye being formed simultaneously and in situ with the development of the image.

Reference will be had to the accompanying 40 drawingin which:

Fig. 1 is a sectional view of a film having three separate emulsion layers;

Fig. 2 is a modified form of lm; Figs. 3, 4, 5 and 6 are sectional views of the film illustrating the condition of the emulsion layers at various stages of the processing.

Fig. 'I is a sectional view of a finished lm having a sound track recorded in three layers. Y In practicing the invention we prefer to use a iilm of the type illustrated in Fig..1 in which I0 is the usual type of transparent base such as cellulose nitrate or cellulose acetate. The sensitized silver halide emulsions are' coated on one side of this base in three layers, the layer II coated next to the base being sensitive to red light, the intermediate layer I2 sensitiveto green light and the top or outermost layer I3 sensitive to blue light. These layers are preferably'separated by layers of inert material such as gelatin illustrated at I4 and I5. The layer I5 may con- 5 tain a yellow dye in order to filter out blue light and prevent it-from reaching the layers II and I2, which, while sensitive to red and green, are also sensitive to blue light. This yellow dye may,

if desired, be'incorporated in the outer blue sen- 10 sitive layer I 3.

The layers II and I2 are the usual silver halide emulsion layers sensitized to red and green light, respectively, with sensitizing dyes which are well known in the art. A suitable red sensitizing dye 15 is naphthocyanol, and a suitable green sensitizing dye is erythrosin.

The process may be considered as divided into a series of units, each comprising a number of steps, and we will designate these as units A, B, and C.

This film is exposed in the usual way to form an image and since no filter is essential except that which is incorporated in the film itself, a shorter exposure may be made than with colored films heretofore used. However, a lter may be used to overcome errors in the color ratio, or to produce special eects.

In treating the film after exposure a reversal development may be used, thus forming a posi- 30 tive picture directly or the film may be developed as a negative and positives printed from it. An essential feature inthe processing is a differential treatmentV of the layers by means of which the outer layer I3 may be treated without aifect- 35 ing layers I I and I2 or the outer layers I2 and I3 may be treated without affecting layer II. In order to aid in treating only the desired layers, the inert gelatine layers I4 and I5 are inserted between the sensitized layers to allow the opero ator some leeway. It has been found, however, that the differential treatment of the layers can be controlled with such a degree of accuracy that these inert layers are not absolutely necessary and in Fig. 2 a modification of the film is illus- 45 trated in which the sensitized emulsion layers are coated-directly one on top of the other.

The process will first be described with'reference to a reversal development. In using a film such as that illustrated, in which the base is 50 coated with layers sensitive to three colors, the process steps may be divided into three separate units, at the end of each' of which one of the layers is colored with the dye winch it finally retains. Referring to Figs. 3 to 6 the steps of 55 unit A will now be described. The illm after exposure contains latent images in each of the three emulsion layers, I I, I2 and I3. These are illustrated in Fig. 3, I6 being the latentv image corresponding to the red of the object photographed, I1 the latent image corresponding to the green and I8 the latent image corresponding to the blue. The film is developed in an M-Q developer, forming silver images I9, 20 and 2| corresponding, respectively, to the red, green and blue of the object photographed.

A suitable developer has the formula:`

The ilim is next washed and then bleached in a bath which removes the silver but does not attack the silver halide present in each layer.

This bleach bath may have the followingcomposition:

Grams Potassium permanganate (4% solution).... 1 Sulfuric acid (20% solution) 1 Water 20 After the bleaching, the film is again washed, and then subjected to a clearing bath oi sodium 0r potassium bisulfite or any other bath capable of removing from the lm the manganese compounds or any other products that may have been formed in the bleaching operation. The customary bath for this purpose is a 2% solution of sodium bisulflte. The illm is again washed, and is then ready to be exposed. Each of these washing steps, as well as the clearing bath, is carried out at 70 F. for about 4 minutes. The bleach bath is kept at a slightly lower temperature, about 65 F. f

The developer contains, in addition to the usual developer constituents, including a para-amino aniline as the developing agent, a coupling or dye-forming compound such as any of the hydroiw diphenyls described in my copending application, Serial No. 8,520, led February 27, 1935, inatgred into U. S. Patent No. 2,039,730, of May A suitable developer is the following:

(a) p-Amino diethyl aniline monohydrochloride g-- 3 Sodium sulfite g-- 5 Sodium carbonate g-- 50 Potassium thiocyanate g-- 1/2 Water to cc 1000 .(b) m-Hydroxy diphenyl g-- 21/2 Methyl alcohol." cc 100 (In use, b is added to a) Since the oxidation illustrated at Fig.'6 and contains the threelayer images consisting of metallic silver and blue-green dye at 25, 26 and 21. The film is then xed to removel any residual silver halide which may be present, washed, and thoroughly dried. This completes unit A.

The first step of unit B is the de-coloring of the dye in the outer layers I2 and I3, and the re-conversion of the metallic silver in these layers to silver halide. This may be done by the use of a bleach bath consisting of a solution of quinone and concentrated hydrochloric acid containing a retardant such as glycerine and isopropyl alcohol to control the depth of penetration of tlie bleach.

Such a bath may have the composition:

Glycerine cc 500 Iso-propyl alcohol cc 1000 Water cc 75 Quinone g-- 5 Hydrochloric acid (conc.) g 20 Sodium bicarbonate g-- l5 Iso-propyl alcohol cc 1000 Glycerine cc 1000 Water cc 1000 The stop bath which will be used will depend, of course, upon the type of bleach bath used, an alkaline stop bath being used to neutralize the action of the acid bleach bath. The dye contained in the outer layers I2 and I3 has now been de-colorized and the silver converted to silver chloride at the points at which there was a bluegreen silver image at 26 and 21 in these layers. The lm is then washed to insure removal of the de-colorized dye compounds and is then redeveloped in a second color-forming developer which develops the silver chloride in the outer o layers I2 and I3 to metallic silver and forms a magenta dyev at the points at which the silver is formed. Such a developer may contain as the color-forming component p-nitro phenyl aceto nitrile, which couples with the oxidation product of the developer.

The magenta developer may have the following composition:

(a) 2-amino 5diethyl`amino toluene hy- (In use, b is added to a) The film is now Washed and dried. A'I'his completes unit B, and the lm now contains a. blue-green image in the innermost layer II and magenta images in the layers I2 and I3.

`As the first step in unit "C" the magenta. dye lcontained in the outer layer I3 is bleached and the silver re-converted to silver halide. The bath used for this purpose is similar to the bleach bath used in unit B although the treatment is for a shorter time, for example two minutes at 72 to 74 F. The action of this bath is terminated by a stop bath as in the case of unit B and the' (a) p-Amino dimethyl aniline sulfate g 1 Sodium sulflte g 2 Sodium carbonate -g-.. 30 Water to cc-.. 1000 (b) 4-nitro acetoacetanilide g 2% Iso-propyl alcohol cc (In use, b is added to a.)

The film now contains a blue-green image in the inner layer Il, a magenta image in the intermediate layer I2 and a yellow image in the outer layer I3, together with metallic silver in each of the layers. 'I'he metallic silver is removed in a suitable bath such as potassium ferricyanide solution, leaving the film as illustrated in Fig. 7 (where a sound track is included), the emulsion layers now containing blue-green image 29 in the inner layer. magenta image 30 in the intermediate layer, and yellow image 3l in the outer layer. The film is then washed and dried.

We have described our process employing a film in which the emulsion layers are sensitized, from the base to the outer surface, to red, green, and blue light, respectively. 'I'he emulsion layers need not, however, be coated on the film in this order. For example, the green sensitive emulsion. might be coated next to the base.

If it is desired to produce a, negative from which positives may be printed, the exposed film mayy be treated in various ways.

(1) The film is developed in an ordinary metolhydroquinone type of developer which may -have the same formula as that used for the first development in the reversal processing. The film is ihen fixed to remove undeveloped silver halide and the remaining silver bleached to silver halide, for example, in a hydrochloric acid oxidizing -bleach bath.. The film is then color developed in a bluegreen color-developer having the same formula as that referred to in the description of the reversal development process. This results in bluegreen negative images in each of the three layers.

'I'he film is then processed as described above under units B and C. The film then has negative blue-green, magenta, and yellow images in the three layers.

(2) Instead of developing in an ordinary developer, the negative images may be developed directly in a color forming developer. However,

when using this method excessive exposure seems to be necessary. Therefore, the use of a normal black and white photographic developer for' initial negative development is preferable, giving maximum effective speed in the camera. After this color development, the film is treated as described in units B and C above.

(3) 'I'he film containing thelatent images may lbe developed directly in a black and white photographic developer, fixed and bleached in dilute potassium ferricyanide to convert the silver images to silver ferrocyanide. This method is substantially the same as that described under method (l) above, except that the silver images are bleached to silver ferricyanide rather than silver halide. This is sometimes desirable because the silver ferrocyanide produced is very easily reducible back to metallic silver. A suitable bleach for this purpose is:

Potassium ferricyanide grams-- 10 Ammonia- 28% solution cc 10 Water to cc-- 1000 The next step is the exposure and redevelopment of the bleached images in the color forming developer yielding insoluble monochrome dye images together with redeveloped silver. The images in the outer layers are then bleached andI recolored as described above under units B and C. The outer images are preferably bleached to silver halide, although a ferricyanide bleach may be (4) An alternative ferricyanide method may be used and-while it involves more steps.than method 3, it'has the advantage of minimizing any tendency to harden the gelatin in the image portions and, therefore, facilitates the attainment of satisfactory balance between the emulsions throughout the useful density range. By this method, the film is developed, fixed, Washed and bleached in potassium ferricyanide to convert the images in both layers. The film is then exposed and the top layer only redeveloped to silver by controlling the penetration of an energetic developer and arresting the development as soon as the desired depth is reached. This arresting action is attained by loading the developer solution with an arresting agent, such as sodium sulphate. The following developer may be used:

Hydroquinone grams 12.5 Sodium sulflte do 19 Potassium hydroxide do 4l Sodium sulfate do 200 Water to cc 1000 The action of this developing bath is arrested by immediate immersion in a stop bath, kept at very low temperature, for example'O" C. to 5 C. Such a stop bath is Sodium sulfite grams- '50 Glacial acetic acid.l cc 30 Water to cc-- 1000 .These methods of controlling and arresting the action of a bath-so asto restrict its effect to an upper stratum is the subject of co-pending application, Serial No. 8,517,.led February 27,

` used together with an acid to decolorize the dye.

1935 matured into U. S. Patent No. `2,059,887 y of November 3, 1936.

At this stage of the processing, the-film contains a developable silver ferrocyanide .image in the inner layer and metallic silver images in the outer'layers. The film is immersed in a bluegreen color forming developer and the image in the inner layer developed to silver and bluegreen dye. The silver images in the outer layers are, of course,` inert to the color forming developer. 'The silver `images in the outer layers mayl then be bleached in a potassium ferricyanide bath, the diffusion being controlled in the manner described in our said co-pending application SerialNo. 8,517, matured into U. S. Patent No. 2,059,887 of November 3, 1936, to prevent its action on the dyeimage in theinner layer. The silver ferrocyan'ide images in the or more dyes.

outer layers may then be color developed to a single color and the outer layer only bleached and recolored, or the outer layer only may be redeveloped to silver and the intermediate layer then color developed by controlled penetration, and the outer layer nally converted to a silver salt and color developed.

In the negative processing the dyes used in addition to having the property of being easily bleached in the chromic acid, or other bleach by controlling the spectral transmission of the light used for recording the sound track on thel finished print, so that the track is recorded only on the layer or layers sensitive to light of the color used. It is possible to allow the sound track in the various layers to bleach and c olor develop along with the development of the picture portion. or the sound track may be formed of one color in one or more of the layers and the sound track portion of the illmvarnished before the illm is -treated in subsequent treatment baths in order tolimit the sound track toa single color. Fig. 7 shows a multilayer lm in which the base I l carries the three emulsion layers Il, I2 and Il in which an image is recorded and also having a sound track portion 28 having the sound recorded in three layers.

We have described our process as adapted to the lformation of three color component images, since a better,` reproduction of color may be.

obtained in this way. It is apparent, however, that the process is also applicable to the formationof two color component images by treating two diierentially sensitized emulsion layers by the methods described. Where two colors only areused, the emulsion layers are sensitized with suitable color separation dyes, such as blue-green and red-orange.

. Various other modications of the process may' be used. Numerous color forming compounds are suitable, as well as' various bleach and stop baths.v The emulsion layers may be coated on a paper or other support as well as on the trans- `parent illms and plates described. Numerous other modiilcations and variations of the process not herein specifica/ily described are available arid-we intend to be limited only as we are restricted by the appended claims.

What we claim is:

1. The process of producing a colored photographic record on a sensitive element having a plurality of superposed, differently sensitized sily ver halide layers, which comprises simultaneously forming latent images in the layers, the images being dierent .color sensation records of a subject, simultaneouslysdeveloping the latent images to metallic silver images, bleaching the images to remove the silver, exposing the sensitive element to light, redeveloping the images' in a color-forming developer, selectively bleaching at least the outer layer and redeveloping said last mentioned layer in a developer.

2. 'I'he process of producing a colored photographic .record on a sensitive element having three superposed, differently sensitized silver halide layers, which comprises simultaneously forming latent images in the layers, the images being different color sensation records of a subject, simultaneously developing the latent images to metallic silver images, bleaching the images to remove the silver, exposing the sensitive element to light, ,redeveloping the images in a coloriorming developer, selectively bleaching the two outer layers, redeveloping the two outer layers in a second color-forming developer, bleaching the outer layer and redeveloping it in a third color-forming developer.

3. 'Ihe process of producing a colored photographic record on a sensitive element having a plurality of superposed, diierently sensitized silver halide layers, which comprises simultaneously forming latent images in the layers, the images being diiIerent color sensation records of a subject, simultaneously developing the latent images to metallic silver images, bleaching the images to remove the silver, exposing the sensitive element to`light, redeveloping the images in a color-forming developer in which a color second color-forming is formed simultaneously and in situ with development of a silver image. selectively bleaching at least the outer layer and redeveloping said last mentioned layer in a second color forming developer.

4. 'I'he process of producing a colored photographic record on a sensitive element having a plurality of superposed. diilerently sensitized silver halide layers, which comprises simultaneously forming latent images in the layers, the images being different color sensation records of a subject, simultaneously developing the latent images to metallic silver images, bleaching the images toremove the silver, exposing the sensitive element to light, redeveloping the images in a color-iormlngdeveloper in which a`color is formed by chemical coupling of a color-forming compound presenti 'the developer with an oxidation product of' the developer, selectively bleaching at least the outer layer and redeveloping said last-mentioned layer in a second color-forming developer.

5. The process of producing a colored photo? veloper, ilxing out the unexposed silver halide,-

selectively bleaching at least the outer layer and redeveloping said last mentioned layer in a colorforming developer.

6. 'I'he process of producing a colored photographic record on a sensitive element having a plurality of superposed differently sensitized silver halide layers which comprises simultaneously exposing from the same .side to form latent images in the layers, the images being different color sensation records of a subject, simultaneously developing the latent images to metallic silver and dye images by means of a color-formingdeveloper in which a color is formed by chemical coupling of a color-forming compound present in the developer with an oxidation product ot fix the developer, ilxing out the unexposed silver halide, selectively bleaching at least the outer layer and redeveloping said last mentioned layer in a color-forming developer.

7'. The process of producing a sound track on a sensitive element having a plurality of ysuperposed differently sensitized, silver halide layers which comprises forming a latent image of the sound track in each layer, developing said 1atent images to metallic silver, bleaching the images to remove the silver, exposing the sensitive element to light, redeveloping the images in a color-forming developer, selectively bleaching at least the image in the outer layer, and redeveloping said last-mentioned layer in a second color-forming developer.

8. The process of producing a sound track on a sensitive element .having a plurality of superposed, differently-sensitized, silver halidelayers which comprises forming a latent image of the sound track on the sound track portion of the illm, developing said latent image to metallic silver and dye images in a color-forming developer, coating the sound track portion of the illm.

with a material impervious to subsequent treatment baths, and processing the film to produce color component images in the remaining portions of the film.

9. 'I'he process of forming nent images in registry in two diierent strata on the same side of a photographic support that comprises forming acolor component `latent image in each stratum by exposing the strata from the same side of the support, developing each latent image into a silver image by a process which includes also the development of a color image in the lower stratum, subjecting the element for a controlled time to a bleaching bath containing a retardant for the diffusion thereof whereby the effect of the bath is limited to the upper stratum and the image therein is transformed into a developable image, and developing said image into a color image of different color than the image in the lower stratum.

10. The process of forming two.color component images in registry in twodifferent strata on the same side of a photographic support that comprises forming a color component latent image in each stratum by exposing the strata from the same side of the support, developing each latent image into a silver image by a process which includes also the development of a color image in the lowerstratum, subjecting the element for a controlled time to a bleaching bath containing a retardant for the diffusion thereof whereby the effect of the bath is limited to the upper stratum and the image ,therein is transformed into a developable image, and developing said image into a silver image and a color image of a different color than the image in the lower stratum, and removing the silver images from both layers, leaving differently colored images in the respective strata.

1l. The process of forming two color component images in registry in two different strata on the same side of a photographic support that comprises forming a color component latent image in each stratum by exposing the strata from thesame side of the support, transforming each latent'image into a silver image by a process which includes also the development of a color image in the lower stratum, subjecting the element for a controlled time to a bleaching bath containing a retardant ,for the diffusion thereof whereby the effect of the bath is limited to the two color compoupper stratum and the image therein is transformed into a developable image, and developing said image into a color image of different color than the image in the lower stratum.

12. The method of making a color photograph that comprises forming two images of silver and dye in different strata on the same side of a support by exposing the strata from the` same side of th'e support, bleaching only the-outer image in a bath that transform the silver into a developable salt and decolorizes the we and then redeveloping in a single step the outer image only into an image of silver and of dye of different color from the first named dye.

13. The method of making a color photograph that comprises forming two images of silver and dye in different strata on the same side of a support by exposing the strata from the same side of the support, bleaching only the outer image in a bath that transforms the silver into a developable salt and decolorizes the dye and then redeveloping in a single step the outer image only into an image of silver and of dye of different color from the iirst named dye and then removing the silver from both images, leaving in the diilerent strata dye images of diiferent colors.

14. The process of forming two color com- \ponent images in registry in two different strata on the same side of a photographic .support that comprises forming a color component latent im- 1 age in each stratumbyexposing the strata from .the same side of the support, transforming both latent images by a single process into images of metallic silver and of the same dye by color developing, bathing the outer image only in a bath that transforms the silver image into a metallic salt image and that removes the dye and then treating the metallic salt image to form an image complementary in color to the image in the inner 15. The method of making a color photograph in an element having sensitized material in layer form on one side of a support, that comprises forming two images of the same color in two dierent strata of said sensitized material by exposing the strata from the same side of the support, submitting said element to a bath that diffuses into said material and is capable of decolorizing said images, said bath including a re tardant for the diffusion thereof, stopping the action of the bath when the outer image only has been decolorized and then coloring said outer image .a different color than the lower layer.

16. 'Ihe process of forming two color component images in registry in two different strata on the same side of a photographic support that comprises forming a color component latent image in each stratum by exposing the strata from the same side of the support, transforming both latent images by a common process into images of silver and of the same dye, bathing the outer image only in a bath that transforms the silver image into a metallic salt image and that removes' affected by said bath, quickly submitting the photographic element to a bath that immediately arrests the action of the first named bath and then treating the metallic salt image to forman image complementary in color to the image in the lower stratum.

17. 'I'he process of producing a colored photographic record on a sensitive element having a. plurality of superposedl diiferently sensitized silver halide layers, which comprises simultaneously forming latent images in the layers, the images being different color sensation records of a subject, simultaneously developing the latent images to metallic silver images, bleaching the plurality of superposed differently sensitized silver halide layers, which comprises simultaneously exposing from the same side to form latent images in the layers, the images being dllerent color sensation records of a subject, simultaneously developing the latent images to metallic silver and dye images by means of a color-forining developer, fixing out the unexposed silver halide, selectively bleaching at least the outer layer to remove the dye and convert the silver to silver chloride, and redeveloping said last-mentioned layer in a color-forming developer. LEOPOLD D. MANNES. LEOPOLD GODOWSKY. Jn.