DE1597550B - Production of colored pictures by the silver color bleaching process - Google Patents

Description

The invention relates to the production of colored images by the silver dye bleaching process in which a color photographic material having at least one light-sensitive silver halide emulsion layer and at least one bleachable dye imagewise exposed and developed as well as the Dye is bleached on the resulting silver image.

The production of multicolored images by the silver dye bleaching process is based on use color photographic materials comprised of a plurality of superimposed silver halide emulsion layers consist, each of which contains a bleachable azo dye, its color the color of the spectral range in which the relevant silver halide layer is sensitive, is complementary. Such a photographic material is exposed to light, developed and then treated in a bleach bath in which the dyes correspond to that formed during development metallic silver can be discolored. After removing the remaining silver and silver halide bleaching the silver, fixing the silver halide and washing gives a positive one Dye image. However, such a silver dye bleaching method has a disadvantage that the photosensitive Silver halide emulsion layers incorporated azo dyes in a substantial amount absorb the incident light, increasing the effective sensitivity of the material considerably is decreased.

Attempts have been made to avoid this disadvantage by separating the dyes from under the layers lying on the silver halide layers. While such an arrangement of the dyes improved the effective speed of the film somewhat, it was due to the increasing thickness of the film, however, results in blurred images as the incident light is scattered and the dye fade catalyst to cover a greater diffusion path on its migration from silver to dye has.

Other attempts to overcome these shortcomings, e.g. B. by a changed arrangement of the Layers, d. H. an arrangement different from the normal arrangement: blue sensitive layer, yellow filter layer, green-sensitive layer, red-sensitive layer, layer support deviates, or coloring of the Films after exposure were also found to be unsatisfactory.

Also the replacement of the azo dyes by the most varied forms of colorless compounds, the form dyes during the silver dye bleaching process, such as by nitroso compounds or azo couplers, were found not to be particularly beneficial in converting these compounds makes at least one additional treatment step necessary in their corresponding dyes.

Finally, it is common silver azo dye fade materials to increase the sensitivity also known to incorporate special azo dyes into the material, which depend on the pH value of the surrounding medium can be colored differently. At the time of exposure these point pH-sensitive dyes such colors indicate which light of the wavelengths compared to which the these Layers containing dyes or the layers below these layers are sensitive are, let through. These materials have therefore not proven to be particularly advantageous, as an additional, The pH-changing treatment bath is required to change the hue of the dyes to shift far so that the pictures get the desired coloring. Another disadvantage of such The method using materials consists in the fact that the special dyes have only a low stability own.

Another difficulty encountered with the use of azo dyes is limited Selection of dyes, especially cyan dyes. Many azo dyes in themselves due to their ability to fade and their compatibility with silver halide emulsions for the production of Silver dye bleach materials would be suitable, due to their inadequate stability, their unsuitable broad absorption bands and their absorption not in the appropriate wavelength range Not used.

The invention was therefore based on the object of specifying a silver dye bleaching process in which Implementation of the image-generating dyes and substances used the effective sensitivity of the silver halide emulsion layers during their exposure do not counteract the imaging dyes, especially those sensitive to green and red Emulsion layers associated dyes have improved spectral properties and the under Use of the dyes mentioned produced color images against light and unfavorable atmospheric conditions Conditions have good stability.

The invention was based on the knowledge that the task at hand can be achieved by using Formazan dyes, formazan dye chelates and colorless tetrazolium salts, which are hereinafter also referred to are referred to as formazan dye formers, can be solved.

The subject of the invention is the production of colored pictures according to the silver color bleaching process, wherein a color photographic material having at least one light-sensitive silver halide emulsion layer and at least one bleachable dye imagewise exposed and developed as well as ( the dye is bleached on the resulting silver image, which is characterized in that one a color photographic material is used which has at least one formazan dye, a chelate of a formazan dye or a colorless compound produced by reduction forms a formazan dye during development.

Conventional azo dye fade procedures can be used in practicing the process of the invention operate without the need for additional treatment steps. After the procedure of the invention, both monochrome and multicolor formazan dye images can be obtained will. The formazan dye images obtained by practicing the process of the invention represent Reverse images of the silver images. Preferably, those formazan compounds are used which do not diffuse in hydrophilic colloids.

In a particularly advantageous embodiment of the method of the invention, an exposed A photographic material comprising a light-sensitive silver halide emulsion layer and a

colorless tetrazolium salt in contact therewith in the presence of a weak reducing agent, e.g. B. the photographic developer or one Auxiliary reducing agent, brought to a higher pH, making the tetrazolium salt evenly is converted into a formazan dye throughout the photographic material. When performing the The process becomes metallic using the silver halide developer in the layer Silver image developed and the formazan dye imagewise, d. H. in the areas of the metallic silver picture, faded. Preferably, the image of the finished photographic copy consists only of Formazan dyes or formazan dye chelates.

The tetrazolium salt can be in the silver halide emulsion layer or in one adjacent thereto Layer be included.

According to a further advantageous embodiment of the method of the invention, at least one of the formazan dyes present in the silver dye bleach material by chelating with a stabilized suitable metal compound and converted into a different colored compound. Such a one Chelation of a formazan dye can either be prior to incorporating the dye into the silver dye bleach material or during the development of that material.

The method of the invention is particularly advantageously suitable for the production of multicolored Photos. In this case, a photographic material composed of a support is used with at least three separately superimposed, hydrophilic colloid layers applied to it, which are sensitive to red, green and blue light are used. The single ones Layers of this photographic material are each associated with a formazan compound, (i.e., a Formazan dye or a tetrazolium salt) in contact, the blue-green, purple or yellow dye images deliver. These cyan, magenta, or yellow dye images can thereby be produced that one formazan dyes of the respective colors, tetrazolium salts, from which formazan dyes such colors are formed, formazan dye chelates or formazan dyes, which in a Chelation to give blue-green, purple or yellow compounds is used.

In the first step of the process of the invention the exposed photographic material is with treated with a silver halide developer, with a metallic silver image in at least one of the layers is being developed. As the silver halide is developed, the pH of the photographic becomes Material usually increased sufficiently so that a uniform formation of the formazan dye in the layers containing a formazan dye former.

The second stage of the method of the invention is a bleaching process in which the formazan dye in contact with any layer in which a silver image has formed is destroyed image by image. The metallic silver and the silver halide are then extracted from the photographic material removed. Chelation of the formazan dye can optionally occur take place in order to achieve a suitable coloring or to increase the stability of the formazan image raise.

Tetrazolium salts particularly useful in practicing the process of the invention can be used represented by the general formula I. They can be reversible in general formazan dyes Formula II can be converted according to the equation given below.

R ₁ -N NR ₃

R ₂

(i)

reduction

oxidation

H
NR ₃

(Π)

In the given formulas I and II, Υ ^{Θ denote} an anion, R ₁ and R ₃ optionally substituted aryl or heterocyclic radicals, which preferably contain 5 or 6 atoms and nitrogen, sulfur, oxygen and / or selenium as heteroatoms, and R ₂ Hydrogen atom or an optionally substituted aryl or heterocyclic radical, which preferably contains 5 or 6 atoms and the heteroatom nitrogen, sulfur, oxygen and / or selenium or an alkyl, hydroxyl, carboxyl, sulfonyl, mercapto or nitro radical.

Suitable radicals R ₁ , R ₂ and R ₃ are, for example, optionally substituted phenyl, naphthyl, thiazolyl, benzothiazolyl, oxazolyl, benzoxazolyl, selenazolyl or benzoselenazolyl radicals. R ₂ can also have the meaning of an alkyl radical, e.g. B. a methyl, butyl, hexyl or dodecyl radical.

Other suitable substituents by which the formazan dyes or tetrazolium salts are substituted can be z. B. in the journal "Chemical Rev.", 55, pp 355 to 483 (1955), described.

The substituents R ₁ and R ₃ can optionally contain radicals with free electron pairs which are capable of forming metal chelates or complexes. Examples of such chelating or complex-forming groups are primary, secondary and tertiary amino, imino, substituted imino, oxime, thioether, keto, thioketo, hydroxyl, mercapto, carboxyl, sulfo, phospho as well as alkoxy radicals or complexes.

Formazan dyes and tetrazolium salt precursors useful in practicing the process of the invention are also the bis compounds of the following general formulas III and IV.

θ
R ₁ -N-

Il

-Ν — X-N-

I I

N N

-NR ₃ N

^S C ^X
R ₂

R,

(III)

Υ ^ΘΘ ίο

reduction

R ₁ -N

H H

I I

Ν — Χ — N N N

oxidation

NR ₃

20th

C ⁷

R ₂

In the formulas, Υ ^{θΘ is} an anion and X is an alkylene or arylene radical, and R ₁ , R ₂ and R ₃ have the meanings already given.

Tetrazolium salts and formazan dyes useful in practicing the process of the invention are for example:

Connect R. R ' TT R " manure 4-OCH3 No. -NO ₂ TT 1 -NO ₂ TT 2

Connect R. R ' TT R " manure - H No. - H - H TT 3 -OCH ₃ 4-CH ₃ TT 4th CH3 - H - H 5 -NO ₃ 4-Cl - H 6th -Cl 4-NO ₂ - H 7th -NO ₂ - H - H 8th -NO ₂ - H TT 9 -NO ₂ TT -Cl 10 TT - H -Cl 11th -NO ₂ 4-CH = CHC ₆ H ₅ -OCH ₃ 12th -NO ₂ 3-NO ₂ CH ₃ 13th -NO ₂ 3-OCH ₃ TT 14th -NO ₂ TT 15th -NO ₂ - H 16

R-N = N

Br®

C-R '

Connect
manure
No. O ₂ N- R. S0 ₃ e R ' 40 -ό- 17th ~ ^ C \ ~ ^OC 6 ^H 13 45 18th SO ₃ K- so ₃ © - ^^> - OC ₆ H ₁₃ 50 55 19th - ^^ - OC ₆ H ₁₃

connection
No.

20th

OCH ₃ Br®

f V-N = N

// V

OCH,

Connection no.

continuation

CH, - C - S

CH, -C-N

Br ^e

—N = N

N-N

OCH,

_Br e

θ
N = N

/ V ^s \ / V

OCH,

C — Ν — Ν

OH Br ⁰

NaSO ₃

HOOC

N-N

24

©
N = N

C - (CH ₂ ) J-CH ₃ Br ©

C — Ν — Ν

25th

N = N

C- (CH _{2) S-CH3}

COOH

26th

H ₃ CC

H ₃ CC /

^X N

C-N = N

Ν — Ν

Βγ ^θ

27

N = N

Ν — N C1®

connection
No.

28

continuation
OH

ΛΛ-Ν-Ν COOH

ei®

29

30th

NO,

■■ ^>

Cl ©

SO ₃ Na

It is known that tetrazolium salts can be converted into their corresponding formazan dyes. It is also known to contain tetrazolium salts in a silver halide photographic layer to be reduced to formazans in situ with a previously developed silver image. Reference is made to this to British patent specification 908 299 and the work by A. W. Ni η e h a m, "Chemistry of Formazans and Tetrazoliums "published in Chemical Reviews, Vol. 55 (1955), p. 421. This type of Formazan dye formation in a photographic material is different from that Process of the invention, however, not only in that for this purpose a special treatment of the photographic Material in a further treatment solution is required, but also in that the Dyes are formed (simultaneously) in place with the metallic silver image, with im Ultimately, a negative and not a positive copy is obtained.

Finally, it is also known to decolorize formazan dyes in filter layers. The conversion of Formazan dyes to colorless products in filter layers are not done imagewise; H. without Consider reduced or non-reduced silver halide. However, in such a method it is neither intended nor possible to produce color photographic images.

Furthermore, it is known, for. B. from British Patent 884 494, a color change of a pre-formed yellow formazan dye in coupler-containing silver halide color photographic emulsion layers to correct unwanted blue absorption of the developed magenta or cyan dyes. at In this process, the reaction products of the p-phenylenediamine type color developers convert yellow formazan dye corresponding to the metallic silver produced during color development into a colorless connection around. This method differs from the method of the invention in that that the dye, corresponding to the developed silver image, is more likely to be reversible through oxidation corresponding tetrazolium salt is converted as irreversibly destroyed by reduction. Farther the formazan dye also serves in the known process for producing a color correction image to the main images produced by development in the presence of color couplers became.

The drawings serve to explain the method of the invention in more detail. It is shown in detail in

F i g. 1 shows the schematic sequence of the process of the invention in the production of a monochromatic one Dye image using a photographic one containing a colorless tetrazolium salt Materials and

F i g. Figure 2 shows the schematic sequence of the process of the invention in the production of a three-color one Image using a different one in the differently sensitized silver halide emulsion layers photographic material containing colorless tetrazolium salts.

As can be seen from Fig. 1, the monochromatic photographic material consists of a support 10 and a tetrazolium salt-containing photosensitive silver halide emulsion layer 11 applied thereto la and exposed districts 1 b formed. And, during the development in a conventional black-and-white developer solution (step 2) appears in the exposed areas 2 b a silver image while the silver halide in the unexposed areas la is not changed. At the same time, during the phase 2

guided development, the colorless tetrazolium salt is reduced uniformly in the entire emulsion layer 11 (ie in the exposed areas 2b and in the unexposed areas 2 a) to the corresponding formazan dye. The non-reduced silver halide is then made soluble in the areas not affected by the light (la, 2a) in a conventional fixing bath and then removed by washing out. The material is then placed in a dye bleach bath in which the formazan dye in the areas of the developed silver image 2b is destroyed. Finally, the silver is bleached and the material is set and washed to remove all of the remaining silver and silver salt. The image obtained after bleaching and fixing in stage 3 is a positive, colored copy of the original image the districts 3 a of the layer 11 was completely bleached. If necessary, the formazan dye present in the areas 3a of the layer 11 can be converted into a chelate. For example, a purple formazan dye image formed in layer 11 may change color to cyan through chelation.

According to FIG. 2 illustrates the method of the invention with a three-color photographic material, which contains various colorless tetrazolium salts in the individual light-sensitive layers.

The color photographic material used in the present case consists of a carrier 20, a red-sensitive silver halide emulsion layer 21; a green-sensitive emulsion layer 22 and a blue-sensitive silver halide emulsion layer 23. The layer 21 contains a tetrazolium salt, from which a bleachable blue-green dye is formed. Layer 22 contains a tetrazolium salt which can be converted into a bleachable purple dye. the Layer 23 contains a tetrazolium salt, from which a bleachable yellow dye is formed. This in Photographic material constructed in the manner described is exposed imagewise in step 1. In stage 2 arise during the development * of the exposed material in layers 21 (2 c), 22 (2 b) and 23 (2 a) metallic silver pictures. At the same time, those in the individual layers are used during development Tetrazolium salts in the corresponding dyes, namely in layer 21 in a blue-green, in Layer 22 converted to a purple dye and layer 23 to a yellow dye. In stage 3 will removes the undeveloped silver halide from the photographic material, the formazan dye faded image by image in the areas of the metallic silver image and the metallic silver removed. In layers 21, 22 and 23 thus produce a blue-green, purple-red and yellow formazan dye image, respectively. The image obtained is a positive, three-color copy of the original artwork.

The tetrazolium salts and formazan dyes used in practicing the process of the invention can be carried out according to the usual methods, such as those in the journals »Chem. Rev. «, 55, Pp. 355 to 483 (1955); "J .. Org. Chem.", 25, pp. 575 to 578 (1960), and "Chemischeberichte", 87, p. 1505 (1954).

The following are two typical manufacturing processes by which the compounds described can be produced, called:

A. Manufacture of
1,3-diaryl-5- (a-benzothiazolyl) formazan

A suspension of 0.1 mol of an aromatic amine in 21 ml of concentrated hydrochloric acid and 25 ml Water is at 0 to 5 ° C with 8.9 g (0.13 mol) of sodium nitrite, which has been dissolved in 20 ml of water was, diazotized. The resulting diazonium salt solution becomes one at the temperature of one at a time Acetone-dry ice mixture held and violently stirred solution of 0.1 mol of arylaldehyde-2-benzthiazolylhydrazone added in 1 l of tetrahydrofuran. Immediately thereafter, gradually in small Portions of 120 ml of a 20% strength aqueous potassium hydroxide solution were added. During the encore the mixture takes on a deep blue color. After stirring for 1 hour, the mixture is allowed to reach room temperature assume, whereupon 1 1 of water is added and stirring is continued for a further hour. the black precipitate is filtered off and washed with hot water until the Wash water remains clear. By recrystallization from a mixture of tetrahydrofuran and water pure 1,3-diaryl-5- (a-benzothiazolyl) formazan can be obtained.

B. Preparation of 2,5-diaryl-3- (2-benzothiazolyl) tetrazolium bromide

To a hot solution of 0.02 mol of 1,3-diaryl-5- (2-benzothiazolyl) formazan in 1 l of ethyl acetate, a solution of 0.03 mol of N-bromosuccinimide in 250 ml of ethyl acetate is added with stirring. The received The mixture is stirred for 1 hour at room temperature, during which time a yellow precipitate forms separates. The precipitate is filtered off and first with ethyl acetate, then with cold tetrahydrofuran and finally washed with ether. By dissolving the crude tetrazolium bromide in Methanol and reprecipitation with ether can obtain pure 2,5-diaryl-3- (2-benzothiazolyl) tetrazolium bromide will.

In the silver dye bleach materials suitable for carrying out the process of the invention, the tetrazolium salts and formazan dyes can advantageously be used in concentrations of 1.61 to 10.76, preferably 2.15 to 8.61 mg / dm ² carrier area ^{per 10.76 mg silver / dm 2 support area} be used.

The conversion occurring in a silver dye bleach material in the process of the invention a formazan dye of one color to a formazan dye of another color can z. B. perform as follows:

A red sensitive gelatin silver halide emulsion layer which is a colorless tetrazolium salt contains, is exposed and developed in black and white. When developing, the tetrazolium salt uniformly converted into the corresponding purple formazan dye throughout the emulsion layer. The emulsion layer is colored purple-red and contains a visible, negative silver image. During the following treatment in a bleach-fix bath, the dye is correspondingly reduced or reduced. metallic silver decolorized and the reduced silver and the silver halide bleached or fixed, see above that they are in the subsequent watering from the

Allow the emulsion layer to be removed. The resulting positive, magenta formazan dye image is then displayed converted into a positive cyan formazan dye image by placing the film in a suitable Metal salt or a suitable metal complex-containing solution bathes, the dye obtained the desired color and improved stability as a result of chelation.

On the other hand, the dye can also be used before bleaching and fixing or during this process stage, chelated, for example, by incorporating the chelating agent into the bleach-fix bath will.

About migration or diffusion of the dyes or the dye formers from those containing them To prevent film-forming layers, they can do this in a known manner by dissolving them in one with Water immiscible solvent and dispersing fine droplets in the colloidal binder are incorporated into the layers.

Contain the formazan color formers or formazan dyes one or more ballast groups in their molecule, e.g. B. long chain alkyl groups by whose presence the compounds are not diffusible, so they can affect the film-forming material can be added directly. In the latter case, the compounds preferably additionally contain a solubilizing agent Rest, e.g. B. a sulfonic or carboxylic acid residue.

The diffusion of the tetrazolium salts or formazan dyes can optionally also be prevented by that the film-forming layers have a ballast group-containing mordant with acidic Incorporated substituents. Suitable mordant compounds, such as 5- [4- (2,4-di-t-amylphenoxy) - 3 - (phenylcarbamyl) phenylcarbamyl] -1,3-benzenedisulfonic acid, Dipotassium salt, e.g. In U.S. Patent 2,756,149.

The formazan dyes used in the process of the invention bleach in the presence of metallic silver quickly and completely. This is of particular advantage in procedures which have to be done very quickly. In one proposed method, exposed, silver dye bleach materials containing the salt of an acid are developed by exposure to them a developer tape in contact, which contains acidic components, one or more Able to exchange hydrogen ions for the cation of the acid salt, so that the salt in the free Acid is transferred. In doing so, the pH of the layer is reduced and the dye is in the presence a silver complexing agent image-wise bleached in the areas of the metallic silver image. the Silver complexing agent can optionally also be present in the developer belt.

Expediently, between the individual emulsion layers, in the context of the process, the Invention used silver dye bleaching materials arranged hydrophilic colloid interlayers, welehe possibly the most varied of additives, such as, for example, quinones provided with ballast groups (to prevent diffusion of the reduced dye fade catalyst into the interlayer) and removable filter dyes.

The dye chelates useful in the process of the invention have a heterocyclic structure and consist of the connection of a metal atom with one or more formazan dye molecules, those for the formation of two or more coordinative covalent bonds with the metal atom are capable. The improved chelated formazan image dyes are easily passed through Treatment of the dye-containing Ulm-forming layers with a metal compound obtained. Typical metals are, for example, cesium, magnesium, aluminum and the transition metals of the periodic table with atomic weights from about 50 to about 201. Suitable transition metals are for example chromium, manganese, iron, cobalt, nickel, copper, zinc, rhodium, cadmium and mercury.

Suitable metal compounds which can be used in an advantageous manner are, for. B. Salts of these metals, such as nitrates, thiocyanates, sulfates, chlorides, formates and acetates. Also suitable are complex salts of hydroxycarboxylic acids, such as lactic acid, Tartaric acid, citric acid and salicylic acid. All of the hydroxycarboxylic acids mentioned contain the desired metal as a cation.

Further compounds suitable as chelating agents are, for. B. Metal complexes with nitrogen compounds, z. B. ammonia, short-chain aliphatic amines, such as methyl and ethylamine, triethanolamine, Pyridine or amino acids such as glycine.

Although the chelation of the dyes at the time of incorporation into the photographic Material can already have been made, the individual dyes are preferably only after their incorporation into the photographic material, d. H. for example during the treatment of the exposed silver dye bleach material converted into the corresponding chelates. The chelation takes place in an advantageous manner the dyes in the alkaline solution of the black and white developer or in the bleach or fixer bath instead of. The chelation can, however, also take place in a separate aqueous solution containing a chelating agent Solution take place.

The exposed photographic emulsion layers can be developed in the presence of a silver halide developer take place in that the pH of the emulsion layers is increased with an alkaline developer or treatment solution. In the pH of the layers is advantageously increased to 8 or above. It can be of the most varied alkaline solutions such as sodium or potassium hydroxide solutions can be used.

The image dyes are advantageously bleached in the presence of suitable catalysts, such as phenazines, quinoxalines or anthraquinones. Suitable catalysts are z. Described in U.S. Patents 2,183,395 and 2,270,118. The catalysts can the emulsion, the alkaline treatment baths, the acidic developer tape and / or the acidic Dye bleach bath can be incorporated.

example 1

250 mg of Compound No. 27 were dissolved in 30 ml of water with stirring at a temperature of 40 ° C dissolved, whereupon the solution with 30 ml of an orthochromatically sensitized silver bromoiodide emulsion (6 mol percent iodide), which contained 108 g silver and 540 g gelatin per 3 kg emulsion would. The resulting mixture was made on a one-off basis

Cellulose acetate was applied in such a way that approximately 8.61 mg of silver, 43.05 mg of gelatin and 1.99 mg of compound no. 27 were used ^{per dm 2 of support surface.} After drying, a sample strip of the film obtained was sensitometrically exposed through a 0.3 log E neutral density step wedge for 1 second using a copier lamp from a distance of 45.7 cm and then developed in the manner described below.

IO

step 1

Develop for 2 minutes at a temperature of 23.9 ° C in a solution of the following composition: ,

Ascorbic acid 50 g

l-phenyl-3-pyrazolidone Ig

Sodium carbonate, monohydrate 50 g

Potassium bromide 5 g

Benzotriazole Ig

6-nitrobenzimidazole Ig

The pH of the solution was adjusted to 12.0 with 20% sodium hydroxide solution. Then the Solution made up to 11 with water.

While developing a negative silver image arose, the tetrazolium salt reacted with excess Developer, whereby it is uniform in the entire emulsion layer by reduction in the corresponding purple formazan dye is transferred.

Level 2

1 minute fixing of the undeveloped silver halide at a temperature of 2O ⁰ C in a fixer having the following composition:

Water at about 5O ⁰ C 600 ml

Sodium thiosulfate 240 g

Sodium sulfite, dried 15g

Acetic acid (28%) 48 ml

Crystalline boric acid 7.5 g

Potassium aluminum sulfate 15g

Made up to 1 liter with cold water.

level 3

1 minute washing in running water at a temperature of 20 ° C.

Level 4

30 seconds of bleaching at a temperature of 51.7 ° C in a bleach bath of the following composition:

Hydrochloric acid 100 ml

Thiourea 125 g

2-Hydroxy-3-aminophenazine 500 mg

Topped up with water to 11

In the bleach bath described, the dye was imagewise in proportion to the amount of the previously developed silver removed.

Level 5

Wash for 2 minutes in running water at a temperature of 20 ° C.

Level 6

Drying the developed sample strip in warm compressed air. It was an excellent positive, obtained purple copy of the photographed test pattern.

Similar results were obtained with the colorless dye former no. In the spectrophotometric In the curve of the formazan dye produced from this compound, an absorption maximum occurred at 548 nm.

B e i s ρ i e 1 2

Following the procedure described in Example 1, a photographic material was prepared which differed from that described in Example 1 in that the silver halide emulsion used was blue sensitive and the magenta color former of Example 1 by an equimolecular Quantity of color former no. 24 was replaced. Using the produced film, one could excellent positive yellow copy of the photographed test pattern can be obtained. In the spectrophotometric An absorption maximum occurred in the curve of the formazan dye produced from this color former at 433 nm.

B e i s ρ i e 1 3

Following the procedure described in Example 1, a photographic material was prepared which differed from the material described in Example 1 in that the silver halide emulsion used panchromatically sensitized and the purple-red color former used in Example 1 was replaced with an equimolecular amount of color former No. 20. When using the produced film could produce an excellent positive, blue-green copy of the test pattern photographed can be obtained. In the spectrophotometric curve of the resulting from the color former Formazan dye occurred an absorption maximum at 725 nm.

Example 4

320 mg of the purple formazan dye from compound no. 26 were dissolved in 30 ml of water and added with stirring at a temperature of 40 ^° C. to 40 ml of an orthochromatically sensitized silver chlorobromoiodide emulsion which contained 108 g of silver and 600 g of gelatin per 4 kg of emulsion. The coating material obtained was applied to a photographic support made of paper in such a way that 8.61 mg of silver, 53.8 mg of gelatin and 2.87 mg of compound no. 26 were used ^{per dm 2 of the support surface.} After drying, a strip of the film obtained was exposed to light and, as described in Example 1, developed. An excellent positive purple copy of the test sample was obtained. In the spectrophotometric curve of the formazan dye, an absorption maximum occurred at 562 nm.

Example 5

The procedure described in Example 4 was repeated with the exception that the emulsion was only sensitive to blue light and that in place of the purple formazan dye the yellow formazan dye from compound no. 25 was used. It turned out to be an excellent one positive yellow copy received. In the spectrophotometric curve of the formazan dye an absorption maximum occurred at 434 nm.

109525/297

Example 6

a) The procedure described in Example 4 was repeated, with the exception that the emulsion panchromatically sensitized and instead of the purple formazan dye the blue-green one Formazan dye from Compound No. 20 was used. An excellent positive blue-green copy was obtained. In the spectrophotometric On the curve of this image dye, an absorption maximum occurred at about 650 nm.

b) The procedure described under a) was repeated, with the exception that the blue-green formazan dye from compound no. 22 was used would. The copy obtained corresponded to the copy obtained in the process under a). In the According to the spectrophotometric curve of this image dye, an absorption maximum occurred at about 625 nm.

Example 7

layer gelatin
Blue sensitive
Silver bromoiodide
emulsion layer
silver
gelatin
Pickling agent ¹ )
Fading
catalyst ² )
Yellow dye) .. ·
gelatin
2,5-dioctylbenzo-
chinone ^)
Green sensitive
Silver bromoiodide
emulsion layer
silver
gelatin
Pickling agent ¹ )
Fading
catalyst ² ) ......
Crimson
Dye ⁵ )
gelatin
2,5-dioctylbenzo-
chinone ³ ) Support surface
mg / cm ² A.
B.
C.
D.
E. 10.76
'8.72
26.05
21.52
1.07
7.53
8.61
4.31
14.53
24.33
16.36
2.15
6.67
8.61
4.31

IO

layer Red sensitive Support surface Silver bromj odid- mg / cm ² p- emulsion layer silver gelatin Pickling agent ¹ ) 26.90 Fading 33.47 catalyst ² ) 18.30 Bluish green Dye ⁶ ) 4.31 gelatin 6.35 G 10.76

By applying the layers indicated below to a polyethylene terephthalate support a multilayer photographic material was prepared.

') Mordants: poly-a-methylallyl-N-guanidylketimine glycolate (USA.-Patent 2,882,156).
² ) Fading catalyst: 6,7-dimethyl-2,3-dipyridylquinoxaline

(see Belgian patent specification 685 342).
⁶ ) Blue-green formazan dye from compound no. 20.

35

40

45

55

60

') Pickling agents: poly-a-methylallyl-N-guanidylketimine glycolate (U.S. Patent 2,882,156).

² ) Fading catalyst: 6,7-dimethyl-2,3-dipyridylquinoxaline (cf. Belgian patent 685 342).

³ ) 2,5-dioctylbenzoquinone was used to flush out migrating bleaching catalysts (cf. Belgian patent 685 342).

⁴ ) Yellow formazan dye from compound no.25.

⁵ ) Purple formazan dye from compound no.19.

Layer G lay directly on the polyethylene terephthalate support on.

A strip of the obtained film was passed through a neutral density intensity scale test object which was directly was on adjacent strips of a blue, green and red filter, exposed. To After exposure, the film was developed in the manner described below:

step 1

Development for 1.5 minutes at a temperature of 24.4 ° C in a developer with the following composition:

Water of about 50 ⁰ C 500 ml

p-methylaminophenol sulfate 3 g

Sodium sulfite, dried 45 g

Hydroquinone 12 g

Sodium carbonate, monohydrate .... 80 g

Potassium bromide 2 g

Potassium thiocyanate 2 g

0.5% aqueous 5-methyl

benzotriazole solution 10 ml

Topped up with water to 11

Level 2

Seconds rinse in water at a temperature of 20 ⁰ C.

level 3

Minute fixation at 20 ° C in a fixer bath with the following composition:

Water at about 5O ⁰ C 600 ml

Sodium thiosulfate 240.0 g

Sodium sulfite, dried 15.0 g

Acetic acid (28%) 48.0 ml

Crystalline boric acid 7.5 g

Potassium aluminum sulfate 15.0 g

Filled up with cold water to ... 1.0 1

Level 4

Second rinse in water at a temperature of 20 ° C.

19 20

Level 5. This increase in sensitometric values

35 seconds of bleaching of the dye in the case of a Ueß, however, only at the expense of a decreasing one

Temperature of 23.9 ° C in a bleach bath of the fol- Image sharpness of the m these two layers

The following composition: get ₅ drawn pictures.

Concentrated hydrochloric acid 100 ml B e i s ρ i e 1 9

2-Hydroxy-3-aminophenazine *) 150 mg

Thiourea 100 g The procedure described in Example 7 was followed

Repeatedly made up to 11 with water. However, this time a photographic

*) The 2-hydroxy-3-aminophenazine was used for itself in a "cal material, in which the individual

Mixture of 15 ml of water and 15 ml of glacial acetic acid dissolved, whereupon the silver halide emulsion layers incorporated color

obtained solution to the mixture of thiourea, hydrochloric acid substances in these in the form of their corresponding color

and water was added. _{loose tet} razolium salts were present, that is, the

Stage 6 formed dyes of layers B, D and F of the im

-, λ η ι j ο »i - ± -MT ■ -r 15 Example 7 films described were through the

Replace 30 seconds of coils with water of a temperature calibrating colorless compound. Therewith

from to c. So layer B contained the yellow color former

Step 7 No. 25, Layer D the purple color former

1 minute fading of the silver at a temperature no. 19 and the layer F the blue-green color

temperature of 27.8 ° C in a solution of the following zu- ^ o formers no. 20. In addition, contained the used

composition: photographic material in the intermediate layer

_T. ,. , _TT . i_, -j TT / -ν, "η a dispersion of colloidal silver (Carey Lea

Copper (I) chloride · H ₂ O 100 g _{sec over)} £ _{a concentration of 2} i5 mg / dm ²

Concentrated hydrochloric acid 25 ml carrier surface

Filled up with water to 11 ^ _ß |. _{Evaluation of the} exposed and

e, ο wrapped film, carried out sensitometric measurement

^The following results were obtained:
Rinse for 30 seconds with one temperature water

from 20 ° C. 1. Practically the same contrasts, maximum color

30 dense and effective sensitivities for the three separately recorded color images.

1 minute fixation at a temperature of 2O ⁰ C 2. Higher contrasts, maximum dye densities,

Sharpening and effective sensitivities of the specified in step 3 in a fixer

composition. Magenta and cyan dye images in comparison

35 equal to the values of the corresponding color

MuIe IU images in the exposed and treated films

3 minutes washing with water at one temperature, Examples 7 and 8.
temperature of 20 ° C and subsequent drying.

It became a tri-color, positive copy of test example 10
object, whereby exposure through the 40th

Blue filter in the uppermost, ie the blue-sensitive one. The method described in Example 7 emulsion layer gave a yellow color image and was repeated by loading. This time, however, a photographic alignment was used through the green or red filter in the greenish material, which, with regard to the shape or red-sensitive emulsion layer, obtained a purple azane dye in the red or blue-green image described below. 45 way had been modified. The yellow dye, the contrast, the sensitivity and the D- from compound no. 25 were left in layer B, values that were obtained in the originally green- and red-sensitive purple-red dye from compound no. 19 lent emulsion layers its corresponding colorless tetra cyan images were lower than the contrast that zolium salt replaced, and the cyan dye from sensitivity and the maximum dye density in 50 Compound No. 20 and the mordant became the original blue-sensitive layer. That is housed in Layer E instead of in Layer F. Blue-green image had the lowest values. Those with the exposed and developed film _. -ίο results obtained corresponded practically ö e ι s ρ 1 e results obtained with the method described in Example 9 The procedure described in Example 7 was exposed and developed film 55, repeated using a material which only in the layer G recorded cyan yellow dye and the mordant instead of in image had a slightly lower contrast, the emulsion layer (B) in the intermediate layer (C) a lower D _x value and a lower sensitivity and the purple dye and the mordant sensitivity and sharpness,
instead of in the emulsion layer (D) in the intermediate 60
layer (E) contained. Example 11

When comparing the sensitometric results,

A silver chlorobromide (2 mole percent chloride, with the 98 mole percent bromide described in Example 7), gelatin, a mordant results were found that the sensitivity, contrast and coating properties with this photographic material were found to be 65 as well as a tetrazolium salt the density of the in the original composition was applied to a recorded image in such a way that the cellulose acetate support was applied to a recorded image to produce a single silver-blue and green-sensitive emulsion layer that per dm ²

21 22

Support area 10.76 mg silver, 43.04 mg gelatin, 2.58 mg of the mordant of the formula

C ₅ H ₁₁ -I

and 2.69 mg of the tetrazolium salt (2,5-diphenyl-3- (4,5-dimethyl-2-thiazolyl) -tetrazolium bromide) accounted for.

The mordant served to mordant the tetrazolium salt in the obtained photographic material.

The film obtained was cut into three strips, two of which were exposed and the following Way were developed. The temperature of all treatment baths was 23.9 ° C.

step 1

Develop for 10 seconds in a developer with the following composition:

Hydroquinone 10 g

1-phenyl-3-pyrazolidone 5 g

Ascorbic acid 50 g

Aminoethanol 25 ml

Potassium bromide 2 g

0.5% 5-methylbenzotriazole

solution 25 ml

Topped up with water to 11

The pH was adjusted to 12 by adding a 40% sodium hydroxide solution.

Level 2

10 seconds of bleaching in a bleach bath with the following composition:

Thiourea 100 g

Concentrated hydrochloric acid 100 ml

Hydroxyaminophenazine 150 mg

Sodium m-nitrobenzenesulfonate ... 5 g Make up to 11 with water

level 3

By bathing for 30 seconds in 5% aqueous solutions of nickel (II) thiocyanate or cadmium (II) acetate the metal chelates of the dyes present in the two film strips were formed.

SO ₃ K

SO ₃ K

Level 4

Wash with water for 30 seconds. Level 5

Fixing for 30 seconds in a fixer with the following composition:

Water at about 50 ° C 600 ml

Sodium thiosulfate 240 g

Sodium sulfite, dried 15g

Glacial acetic acid, concentrated 13 ml

Crystallized boric acid 7.5 g

Potassium aluminum sulfate 15g

Made up to 1 1 with cold water

Level 6
60 seconds wash with water.

Level 7

Dry.

In each of the two film strips, the almost colorless tetrazolium salt was in the developer bath purple formazan dye 1,3-diphenyl-5 - (4,5 - dimethyl - 2 - thiazolyl) - formazan transferred. This formazan dye was added to the bleach in proportion to the amount formed in the layer metallic silver (i.e. in proportion to exposure). The third filmstrip (control film) was exposed in the same way and, with the exception of the chelating bath, in the same way treated.

All three treated film strips were then cut again into three different strips, two of which were exposed to a xenon arc lamp for 24 and 48 hours, respectively. On that the spectrophotometric curves of the D ^ regions of all nine film strips were recorded. The results obtained are given in the table below.

30th

Post-exposed with a xenon arc lamp

24 hours

Fading
in %

48 hours

Fading in%

Strip A (comparative sample)
not in a chelate bath
treated

Strip B Ni (SCN) ₂ in one
Chelated bath treats

Strip C (CH ₃ COO) ₂ Cd in
treated in a chelate bath

640 656 650

1.72 1.74 2.70 640
656
650

1.08

1.72
2.60

37
1.15

3.7

640
656
650

0.6

1.72 2.5

65 1.15

7.4

The results obtained show:

1. the desired bathochromic absorption shift that occurs when the formazan

. Image dyes in the developed strips B and C in nickel and cadmium chelates, respectively Development of these strips with the described nickel or cadmium salt solution occurred, and

2. A significant improvement in the light stability of the chelated image dyes

compared to the light stability of the same unchelated image dyes.

Example 12

Similar results were obtained when the procedure described in Example 11 was repeated using tetrazolium salts 2, 15, 19 and 21 and a number of other chelating agents. The ^ as "values ^ ^{he n} i ^crit in chelates placed under dyes and placed under chelates dyes are given in the following table:

Metal salt used for chelation

Movie
No. Used
Tetrazolium salt Without
(Comparison test)
A _11111x Nickel (II) -thio-
cyanate Ni (SCN) ₂
'■ _m ax Copper (II) nitrate
Cu ₂ (NOj) ₂
'"Max Cobalt (II) acetate
(CH ₃ COO) ₂ Co
/ ■ ",» * Cadmium (II) acetate
(CH ₃ COO) ₂ Cd (around) (nm) (nm) (nm) (nm) 1 21 562 656 - - 2 15th 502 570 600 542 610 3 19th 550 620 660 564 645 4th 2 498 650 642 600 655

The spectrophotometric curves of the D "," regions were obtained from test strips of the films obtained and after 48 hours of bleaching with a Xenon arc lamp using a 2 B filter recorded. The following table shows the percent fading of the individual dyes for all of them Experiments (i.e. all films or with all metal salts) given.

Movie
No. Used
Tetrazolium salt Without
(Comparison test)
Fading in% Nickel (II) -thio-
cyanate Ni (SCN) ₂
Fading in% Copper (II) nitrate
Cu ₂ (NO ₃ ),
Fading in% iel 13 Cobalt (II) acetate
(CH ₃ COO) ₂ Co
Fading in% Cadmium (II) acetate
(CH ₃ COO) ₂ Cd
Fading in% 1 21 75 2 5.5 2 15th 2.8 '2.4 2.6 - - 3 19th 58.2 6.4 - - - 4th 2 31.6 8.5 1.2 13.0 7.0 B e i s ρ

The following example illustrates suitable pairs of formazan dyes, each of which can be chelated with the same metal compound, whereby in the green-sensitive Layer a stable magenta image and a stable cyan image is obtained in the red-sensitive emulsion layer.

By applying differently modified coating compounds to transparent substrates nine multilayer films were made. All blue sensitive silver halide emulsion layers contained the azo dye Solantine Yellow RL, while the green- and red-sensitive silver halide emulsion layers contained the corresponding magenta and cyan image-forming dyes in the form of their colorless tetrazolium salts. The color formers were the gelatin-containing silver halide layers either together with a mordant or in the form of a dispersion in a suitable solvent such as di-n-butyl phthalate or 2,4-di-t-amylphenol or else in the form of aqueous solutions. In the latter case they had to Color formers on the one hand have sufficient ballast groups so that they do not migrate, and on the other hand be sufficiently soluble, including the presence of at least one solubilizing group in the molecule was required.

All nine films were structured as follows:

₅₅ shift Clear gelatin top layer
Blue sensitive silver
halide emulsion layer
silver Support surface
mg / dm ² A.
B.
60 gelatin 10.76
8.61
25.80
8.61
9.47
4.31 Yellow dye
(Solantine Yellow RL)
Gelatin interlayer
Gelatin ... 65 / ~ l 2,5-dioctylbenzoquinone ..

109 525/297

25th
continuation

layer Green sensitive silver
halide emulsion layer
silver Support surface
mg / dm ² D. Gelatin '. 16.56
32.28
7.53
9.47
4.31 Color formers Gelatin interlayer
gelatin E. 2,5-dioctylbenzoquinone ..

layer 26th Support surface
mg / dm ² F. 24.76
44.13
7.53 5 Red sensitive silver
halide emulsion layer
silver gelatin IO Color formers

Layer F lay directly on the transparent film support.

The films obtained were, as indicated in Example 11, exposed and developed.

The following table shows the magenta and cyan dye images used in each of the nine films generating tetrazolium salts, their colors after the black-and-white development and after chelation and the metals used to chelate each dye pair.

Movie
No. Tetrazolium salt
No in the shift Color and /., "" ,. after
Black and white development 431
499 Color and /. "," ,. after chelation 515
623 For chelation
used metal 1 24 / D
18 / F yellow
yellow 431
499 Purple
Blue green 541
639 } Zinc 2 25 / D
18 / F Light orange
yellow 431
525 Purple
Blue green 515
642 J copper 3 24 / D
23 / F yellow
Purple 431
496 Purple
Blue green 515
642 j zinc 4th 24 / D
28 / F yellow
Purple 431
551 Purple
Blue green 515
653 } Zinc 5 24 / D
19 / F yellow
slightly brownish 502
496 Purple
Blue green 542
676 1 zinc 6th 15 / D
28 / F Red orange
Purple 496
562 Purple
Blue green 676
654 } Cobalt 7th 28 / D
26 / F Pink brown
Pink brown 496
551 Purple
Blue green 676
673 > Cadmium 8th 28 / D
19 / F Pink brown
Pink brown 525
496 Purple
Blue green 536
517 > Cadmium 9 , 23 / D
30 / F Pink brown
Yellow-brown Purple
Blue green > Cadmium

Claims (6)

Patent claims: 1. Production of colored images by the silver color bleaching process, in which a color photographic Material having at least one light-sensitive silver halide emulsion layer and at least one bleachable dye imagewise exposed and developed as well as the Dye is bleached on the resulting silver image, characterized in that a color photographic material is used which has at least one as a bleachable dye Formazan dye, a chelate of a formazan dye, or a colorless compound that forms a formazan dye by reduction during development. 2. The method according to claim 1, characterized in that the formazan dyes by Chelation stabilized. 3. Process according to Claims 1 and 2, characterized in that the colorless, a tetrazolium salt is used by reduction of a compound which provides a formazan dye. 4. The method according to claim 3, characterized in that there is a tetrazolium salt of the following Formula used: R ₁ -N- Il -NR ₃
N- R ₂ in which R ₁ and R _{3 are} aryl or heterocyclic radicals, R _{2 is} a hydrogen atom or an alkyl, aryl, hydroxyl, carboxyl, sulfonyl, mercapto, nitro or heterocyclic radical and Y is an anion. 5. The method according to claim 4, characterized in that the tetrazolium salt used corresponds to the following formula: N-N -N ei ^θ 6. Process according to claims 1 to 5, characterized in that a multilayer color photographic material used. 1 sheet of drawings