US2653874A

US2653874A - Process for the production of color photographic images

Info

Publication number: US2653874A
Application number: US87851A
Authority: US
Inventors: Dreyfuss Paul Daniel
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-04-15
Filing date: 1949-04-15
Publication date: 1953-09-29
Anticipated expiration: 1970-09-29

Description

Sept. 29, 1953 P. D. DREYr-uss PROCESS FOR THE PRODUCTION OF COLOR PHOTOGRAPHIC IMAGES Filed April l5, 1949 y INVENTOR QA-WL @1v/w12 @ffy/fuss,

Patented Sept. 29, 1953 PROCESS FOR THE PRODUCTION OF COLOR PHOTOGRAPHIC IMAGES Paul Daniel Dreyfuss, Van Nuys, Calif., assignor, by mesne assignments, to Bela Gaspar, Beverly Hills, Calif.

Application April 15, 1949, Serial No. 87,851

6 Claims.

This invention relates to the production of dye images from photographic silver images by a process which comprises the synthesis of an azo dye in the exposed photographic emulsion layer.

In the United States Letters Patent 2,071,688 dated February 23, 1937 is described and claimed a method of producing color photographic images in which the photographic layer is subjected to two treatments, the first treatment consisting of the conversion of a dye-forming substance into a dye, and the second treatment consisting of the local dye destruction at the required points. Thus, for example, a diazo compound is transformed into an azo dye by coupling with a phenol; or a phenol or other azo coupler is transformed into an azo dye by treatment with a diazo compound, the azo dyes thus formed then being destroyed locally. In the same patent is described and claimed an alternative process in which the rst treatment consists of the local destruction of the dye-forming substance; the second treatment then consists of the conversion of the remaining dye-forming substance into the dye. Further alternative processes are described in the U. S. Patents 2,166,049; 2,271,176; 2,333,126; 2,361,541; 2,368,463 and in the co-pending patent applications S. N. 518,256 iiled January 14, 1944, now Patent No. 2,514,233, and S. N. 541,282 led June 20, 1944, now abandoned.

It is known that diazo compounds are easily reduced by metallic silver, particularly in the presence of acids. This behaviour of diazo compounds can successfully serve to produce dye images directly from coupling components in one step. This process has the advantage of simplicity, but it is sometimes diflicult to control. A much better control is obtained when the diazo compound is decomposed at a pH which is low enough to avoid coupling at this stage, the coupling being performed in a successive step at a higher pH as described in Letters Patent 2,271,176.

The process, described hereafter, in spite of requiring some additional processing steps has the advantage of being controlled with particular ease and of giving more reproducible results as regards density and gradation of the dye images.

The object of the present invention is the process which consists of a rst treatment whereby a dye-forming substance is converted into a diffusely dispersed dye and in a second treatment whereby the dye is destroyed locally at the required points. More particularly, it is the object of this invention to provide a novel process whereby the contact of free diazo compounds with metallic silver is avoided, the metallic silver images being converted, prior to the diazo treatment, into such other images which are inert towards diazo compounds, said other images being capable of reacting directly or indirectly with the azo dyes formed in the coupling.

Whereas diazo compounds are decomposed by metallic silver in the presence of acids, they are stable in the presence of silver salts. It is therefore possible to produce a dye image in the following way: A photographic material comprising at least one silver halide emulsion layer and an azo coupling component diffusely distributed therein is exposed to light, developed and nxed. Thereupon the metallic silver image is converted into a rsilver salt image and the azo coupling component is coupled with a diazo compound whereby a homogeneous dyeing is produced. The silver salt image is reconverted into a metallic silver image, and the dye is destroyed locally where metallic silver is present. After removing the silver, a dye image is obtained.

The accompanying drawing shows a flow diagram of a modication of the process according to the invention.

The difference in the results between previously known procedures and the process of the present invention is clearly shown by the comparative steps described in Example l below.

Example 1 (a) A light sensitive silver halide emulsion layer is treated in a bath containing 1% N-toluenesulfo-H-acid, thereupon in a solution containing 1% diphenylguanidine acetate, washed and dried. The layer is exposed, developed and iixed in the usual manner. Instead of impregnating the layer with the diphenylguanidine salt of toluenesulfo-H-acid before the exposure, the impregnation may also be effected with the exposed and developed layer containing the silver image.

(b) The layer, treated as above, is immersed in a strongly acid diazo solution, e. g., in a solution containing 0.5% diazotized sulfanilic acid and 1% hydrochloric acid. Thereupon the layer is immersed in a sodium acetate or sodium carbonate solution. The silver is oxidized in an acid copper chloride bath and removed in ahypo bath. A reversed magenta dye image is obtained.

(c) The layer, treated as described in Section a, is immersed in an acid copper chloride bath 3 and washed. Thereupon it is treated in an acid diazo solution and in a buffering solution as described in Section b, and finally the silver is removed in a hypo bath. A uniformly magenta dyed layer is obtained which shows no trace of an image.

(d) The layer, treated as described in Section a, is immersed in an acid copper chloride bath and washed. Thereupon it is treated in an acid diazo solution and in a buffering solution as described in Section b. The silver salt image is reduced in a developer to metallic silver and the azo dye is then destroyed locally in a bleaching bath containing 2% hydrochloric acid and 0.002 2,3-diaminophenazine. After the oxidation of the residual silver in an acid copperA chloride bath and after its removal in a hypo bath, a reversed magenta dye image is obtained. l y

A comparison of the images obtained in the processes b and d shows that the image (d) has much better definition than the image (b) The image (a) being a step wedge which shows 12 steps, the image (d) shows to 11 steps, whereas the image (b) shows only 8 steps. Furthermore the image (d) has much clearer whites at the places of complete bleaching than has the image (b).

As the decomposition of diazo compounds by metallic silver is speeded up by strong acids, the inactivation of the silver image is of particular importance whenever the photographic material must be treated with diazo compounds in the presence of strong acids. This is the case when diazo compounds, such as 1,4-phenylene-tetrazonium borofluoride or 2-bromo-4-nitrobenzenediazonium sulfate, stable only in acid solution, are being used. Other compounds such as antidiazotates, nitrosoarylamides or diazoamino compounds sometimes need strong acids for their conversion into diazonium salts. Still other diazo compounds are best coupled in acid solutions. In all these cases, a homogeneous dyeing of the photographic material is more readily obtained with a process which includes the previous inactivation of the silver image.

This inactivation of the silver image is effected after the development. The removal of the undeveloped silver halide is not necessary at this stage, as it is possible to convert the metallic silver into a compound which is different from the original silver halide; e. g., a layer comprising silver chloride and a silver image is treated in a copper bromide bath. Silver chloride and bromide are attacked with different ease by reducing agents and they have different solubilities in silver salt solvents. It is therefore possible to convert one of said salts into metallic silver while the other of said salts is removed after the azo coupling has taken place.

The preferred inactivated image consisting of silver chloride or silver bromide as the metallic silver image is easily converted into such silver salt image, and this silver salt image can easily be converted into a metallic image which is able to react with the azo dye, with no loss in image details through this chain of reactions.

However, this invention is not limited to the conversion into said salts. The metallic silver images may be converted into silver thiocyanate, into a mixture of silver chloride and mercurous chloride, into complex salts such as ferrocyanides and other compounds which are well known in the arts of reduction, intensiiication and toning of silver images. Many of these compounds are inert with regard to diazo compounds and after- 4 wards can serve for the local destruction of the azo dyes.

The method, consisting of the inactivation of the metallic silver image is suitable for obtaining diffusely dyed layers by diazo coupling, no matter how the diazonium salt is brought into contact with the photographic layers. For example, the diazo compound may be dissolved in a photographic bath which is acid or alkaline or it may be produced within the photographic layer from a diazo forming substance evenly distributed therein.

Eample 2 The following layers are coated in successive order on a transparent film base:

1. A red sensitive silver halide emulsion, having incorporated therein the dye 4-nitraniline-2- sulfonic acid- N-benzoyl-1,5-aminonaphthol in its weakly colored (acidic) form.

2. A silver halide emulsion, which is sensitized for green light and which contains the coupling component N-N(

naphthalene

1,5 disulfo) -8- amino-1naphthol3,6disulfonic acid and the diazo-forming component 2,2-disulfodiphenyl- 4,4-bis-diazopiperidide, both components precipitated with the base described in Example 2 of U. S. Patent 2,317,134, namely, anhydrobiguanidobenzylalcohol acetate.

3. An interlayer containing colloidal silver.

4. A blue sensitive silver halide emulsion containing 1,1-l2,2disulfodiphenylene(4.4)l-bis- [pyrazolone-()-carboxylic acid-(3)] and the same diazo-forming component and precipitating agent as in layer (2) above.

The diazo-forming component 2,2'disulfodi phenyl-4,4-bis-diazopiperidide is prepared by tetrazotiziiig benzidine-2,2'-disulfonic acid and pouring the tetrazotized solution into an aqueous piperidine solution. The barium salt of tlie piperidide is isolated as an oil which is washed with water. It becomes solid by washing with ethanol.

The multilayer material, produced in the indicated manner, is exposed to light, developed and fixed. Thereupon, the superimposed silver images are iehalogenized in a potassium icrricyanide potassium bromide bath. The piperidide is split in a diluted hydrochloric acid bath and the tetrazonium salt, freed in this last bath, is coupled with the azo components by immersing the material in a sodium acetate bath. The silver salt image is reduced in an alkaline developer, and all three of the azo dyes are destroyed in the places where silver is present, e. g., according to Reissue Patent 22,308. The residual silver is oxidized in an acid copper chloride bath and removed in a hypo bath. Finally the lm is treated in an alkaline bath to turn the dye in the bottom layer into its cyan form, and dried.

The splitting of the piperidide and the coupling of the components to form the azo dye can be performed in a single step, i. e., the hydrochloric acid bath and the sodium acetate bath of the above directions are omitted and replaced by a diluted acetic acid or an acetic acid-sodium acetate bath. If the pH of this bath is high enough to ease the coupling, the splitting takes place only slowly. If, on the other hand, the pH is low enough to allow the splitting in a short time the coupling becomes sluggish. A method permittin T the splitting and coupling in one step consists oi' the exposure of the weakly acidic buiered material to a higher temperature, e. g., by hanging the buiiered material in an air current of 50 C. Furthermore, it was found that the splitlfrom the green sensitive emulsion layer (2) and from the blue sensitive emulsion layer (4) and incorporated instead in the interlayer (3).k

Example 3 A red sensitive emulsion containing the azo coupling component .naphthalene-1,5di-(sulfonaphthionyl-1,5aminonaphthol) is coated on a transparent base. On top of this emulsion layer is coated a clear gelatin interlayer and then a high speed green sensitive emulsion containing the n-amyl ether of m-(l\l,N-diethylamino) -phenoi. Thereupon follows a gelatin layer containing a yellow filter dye, and finally the top layer consisting of a blue sensitive emulsion containing N,Ndecamethylene-bis(2,4

dioxo

1,2,8,4 tetrahydroquinoline) The material is exposed, developed, fixed, rehalogenized in an acid copper chloride bath and treated for 7 minutes in a bath containing 1% acetic acid and 0.1% 4-nitro-l-diazonaphthalenec-sulfonic acid. Thereupon it is developed again and treated in a dye destruction bath as in the foregoingexample. After the silver is removed in known manner the material is immersed for a short time in an aqueous solution containing 0.4% ethanolamine and 3% polyethylene glyco1 300 (Carbide & Carbon Corp). After drying, a photograph in natural colors is obtained.

Further applications of this invention are obvious for anyone skilled in the art. For exam- Die, a multilayer material comprising three superimposed silver images may be partially rehalogenized before the coupling. The parts containing metallic silver will produce more contrasty dye images than the parts containing the rehalogenized image. The material may be locally rehalogenized by controlled diffusion of a rehalogenizing or of a redeveloping solution or by local application of the reagents; e. g., the dye formation in the sound track of a film is avoided by the presence of metallic silver only in the sound track, whereas the other parts of the lm are rehalogenized.

Having described my invention, what I claim as new, and desire to protect by Letters Patent 1s:

T. claim:

1. In a process of producing a photographic dye image which includes exposing and developing a silver halide emulsion layer to produce a metallic silver image in said layer, the steps which comprise converting the metallic silver image in the developed emulsion layer into a silver salt image which is different from any remaining silver halide still contained in the layer and which is inert to diazo compounds in acid baths, then treating the emulsion layer containing such silver salt image with a diazo compound under an acid condition, coupling Within said layer said diazo compound with an azo coupling component in the presence of said silver salt image to dye said layer and developing a metallic silver image in said layer from a silver salt thereinand destroying said azo' dye in said layer inproportion to the metallic silver image in said layer.

2. In a process of producing a photographic dye image Which includes exposing and developing a silver halide emulsion layer to produce a metallic silver image in said layer, the steps which comprise converting the metallic silver image in the developed emulsion layer into a silver halide image Which is different from any remaining silver halide still contained in the layer, then treating the emulsion layer containing such silver halide image with a diazo compound under an acid condition, coupling Within said layer said diazo compound with an azo coupling component in the presence of said silver halide image to dye the layer, developing a metallic silver image in said layer from a silver halide therein and destroying said azo dye in said layer in proportion to the metallic silver image within the layer to form a photographic dye image.

3. In a process of producing a photographic dye image the steps which comprise exposing a silver halide emulsion layer, developing said layer to produce a metallic silver image in the presence 0f an undeveloped image of said silver halide, converting the metallic silver image in said layer into an image of a silver halide other than the first mentioned silver halide, then treating the emulsion layer containing said silver halide images with a diazo compound under an acid condition, coupling within said layer said diazo compound With an azo coupling component in the presence of said silver halide images'to dye the layer diffusely, developing a metallic silver image in said layer from one of said silver halide images and destroying said azo dye in said layer in proportion to the metallic silver image Within the layer to form a photographic dye image.

4. In a process of producing a photographic dye image the steps which comprise exposing a silver halide emulsion layer, developing said layer to produce a metallic silver image, fixing out any remaining undeveloped silver halide, converting the metallic silver image in said layer into a. silver halide image, then treating the emulsion layer containing said silver halide image with a diazo compound under acid conditions, coupling within said layer said diazo compound with an azo coupling component in the presence of said silver halide image to dye said layer diifusely, developing a metallic silver image from said silver halide image and destroying said azo dye in said layer in proportion to the metallic silver image within the layer to form a photographic dye image.

5. In a process of producing a photographic dye image which includes exposing and developing a silver halide emulsion layer containing an azo coupling component to produce a metallic silver image in said layer, the steps which comprise converting the metallic silver image in the developed emulsion layer into a silver salt image which is diierent from any remaining silver halide still contained in the layer and which is inert to diazo compounds in acid baths, then treating said layer containing said silver salt image with a solution of a diazo compound under acid conditions, coupling the diazo compound with the azo coupling component within the layer in the presence of said silver saltI image to dye such layer diifusely, developing a metallic silver image in said layer from a silver salt therein and destroying said a-zo dye in said layerzin proportion to the metallic silver image in said layer.

6. In a process of producing a photographic dye image which includes exposing Vand developing a silver halide emulsion layer to yproduce Aa metallic silver image in said layer, the .steps which comprise converting the metallic silver image .in the developed emulsion layer into .asilver salt image which is different from any remaining silver halide still contained in the layer and which is inert to diazo -compounds in 'acid baths, then forming a, diazo compound withinsaid .layer containing said silver salt image under an acid condition, coupling within said layer vsaid diazocompound 'with .an azo coupling component in the presence of said silver saltmage to :dye said layer and developing a metallic silver image in `s'aicl layer yfrom a silver salt therein .and destroying .-8 said azo dye in said layer in proportion to the metallic .silver image in said layer.

.PAUL DANIEL DREYFUSS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,758,572 Lierg May 13, 1930 2,132,154 .Gaspar Oct. 4, 1938 2,179,228 Eggert et al. Nov. 7, 1939 2,251,965 Verkinderen Aug. 12, 1941 '2,333,126 Schwarc Nov. 2, 1943 2,350,736 Ehrenfried June 6, 1944 2,376,822 Schneider et al May 22,1945

FOREIGN PATENTS Number Country Date -503,873 Great Britain Apr. 17, 1939

Claims

1. IN A PROCESS OF PRODUCING A PHOTOGRAPHIC DYE IMAGE WHICH INCLUDES EXPOSING AND DEVELOPING A SILVER HALIDE EMULSION LAYER TO PRODUCE A METALLIC SILVER IMAGE IN SAID LAYER, THE STEPS WHICH COMPRISE CONVERTING THE METALLIC SILVER IMAGE IN THE DEVELOPED EMULSION LAYER INTO A SILVER SALT IMAGE WHICH IS DIFFERENT FROM ANY REMAINING SILVER HALIDE STILL CONTAINED IN THE LAYER AND WHICH IS INERT TO DIAZO COMPOUNDS IN ACIDS BATHS, THEN TREATING THE EMULSION LAYER CONTAINING SUCH SILVER SALT IMAGE WITH A DIAZO COMPOUND UNDER AN ACID CONDITION, COUPLING WITHIN SAID LAYER SAID DIAZO COMPOUND WITH AN AZO COUPLING COMPONENT IN THE PRESENCE OF SAID SILVER SALT IMAGE TO DYE SAID LAYER AND DEVELOPING A METALLIC SILVER IMAGE IN SAID LAYER FROM A SILVER SALT THEREIN AND DESTROYING SAID AZO DYE IN SAID LAYER IN PROPORTION TO THE METALLIC SILVER IMAGE IN SAID LAYER.