JPS5945144B2 - Bleaching method for color photographic materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for photographically processing a silver halide color photographic light-sensitive material, and particularly to a rapid bleaching method for color photographs in which environmental pollution caused by wastewater can be ignored.

In photographic processing of silver halide color photographic light-sensitive materials, the light-sensitive material (silver halide photographic emulsion may be fogged in advance) after exposure.

) is developed with a developer containing an aromatic primary amine developing agent in the presence of a color-forming coupler to obtain a color image, and the simultaneously produced developed silver is rehalogenated by bleaching and is then combined with the undeveloped silver halide. Removed by fixing (or bleach-fixing). Conventionally, red blood salt (ferricyanide), ferric chloride, aminopolycarboxylic acid ferric complex salt, etc. have been mainly used as bleaching agents.

However, if these bleaches are mixed into wastewater, they cause environmental pollution, and to prevent this, it is necessary to recover these bleaching agents. Bleaching baths used in color photographic processing must not destroy the dyes or dye intermediates produced during color development. The use of bleaching powder and sulfamic acid as a bleaching agent for color photographic materials was established in 1973.
No. 1068, this bleaching agent causes destruction of pigments, leading to changes in hue and loss of density of color images. In addition, this bleaching method causes pollution problems due to bad odors caused by the bleaching powder. Although it was known to use free chlorine in the bleaching process of color photographic materials, it had serious drawbacks and could not be put to practical use. One possible method for silver bleaching color photographic materials is to use free bromine. Free bromine can be generated by electrolytically oxidizing bromide ions in an aqueous solution. When an aqueous solution containing bromide ions is electrolyzed using a carbon anode, an oxidation reaction occurs at O, 8 V (vs. saturated Kanaga electrode) or higher, and an oxidizing agent (Br2) capable of bleaching silver is provided. However, Br2 has a bad odor and is toxic.
Furthermore, when this was tried to be used as a photographic bleaching agent, its oxidizing power was too strong, leading to destruction of dyes and gelatin crosslinking, making it extremely difficult to use it as a photographic bleaching agent. These drawbacks could only be solved by coexisting ammonium ions in the bromine source. The first object of the present invention is to provide a method for bleaching color photographic materials in which environmental pollution caused by wastewater can be ignored.

A second object of the present invention is to provide a method for bleaching color photographic materials that does not require recovery of bleaching agents in order to prevent environmental pollution.

A third object of the present invention is to provide a method for bleaching color photographic materials that causes less damage such as decomposition of dyes.

The above objects of the present invention are to achieve exposure and development (black and white development and/or
When bleaching a silver halide color photographic material that has been subjected to color development or color development, bromine (BrOmine) is removed by electrolytic oxidation.
) is obtained by coexisting bromine and ammonium ions, which are generated by electrolyzing an aqueous solution containing a water-soluble compound which generates This was effectively achieved by a method of bleaching using a bleaching solution having bleaching activity.

Since the bleaching solution according to the present invention does not cause destruction of dyes or gelatin crosslinks, it is presumed that a relatively stable reaction intermediate is produced by ammonia and bromine generated by electrolysis. It is thought that this intermediate acts as a good bleaching agent. Water-soluble compounds that generate bromine through electrolytic oxidation can be selected from bromine-containing inorganic compounds and organic compounds, such as alkali metal bromide salts (e.g., sodium salts and potassium salts), water-soluble bromides such as ammonium bromide, etc. , water-soluble bromates (counter ions include, for example, the above-mentioned alkali metal ions and ammonium ions), tetraalkylammonium bromides (eg, tetramethylammonium bromide, tetraethylammonium bromide, etc.), and the like.

Among these, salts that dissociate bromide ions in an aqueous solution, such as alkali metal bromide salts and ammonium bromide, are preferred.
Particular preference is given to using ammonium bromide. That is, the bromide ions used in the present invention are a source of bromine, and also act as a counter ion for silver ions produced by bleaching, thereby acting as a promoter of the bleaching reaction.

The specific amount of the bromine generating compound added is approximately 5.times.10@-3 to 3 mol per ton of electrolytic solution. The preferred amount to be added can be appropriately determined by conventional experimental procedures. Water-soluble compounds that generate bromine through electrolytic oxidation are typically salts that release bromide ions in aqueous solution, as mentioned above, so we will refer to them as "bromide ions" below. .

It is appropriate that ammonium ions be contained in an amount of about 0.1 to 5 moles per ton of aqueous solution containing them (the preferred amount can be determined as appropriate), and halides (such as bromides and chlorides) should be added to the aqueous solution. etc., of which bromides are preferred) or as aqueous ammonia. In addition, water-soluble salts such as sulfates and nitrates may be added. As for the ratio of bromide ion and ammonium ion, both may be used so that the amount of coexisting M-maru+ is greater than the amount of bromine generated. For example, the use of ammonium bromide satisfies this condition. On the other hand, if the concentration of NH3 in the reaction system does not satisfy the above conditions, it may be replenished by adding aqueous ammonia or ammonium bromide. The bleaching solution...is about 5-9.
A value of 5 is appropriate, and a value of 7 to 8.5 is particularly preferred.

For this purpose, the initial pH of the solution that starts electrolysis may be set a little higher (for example, about 0.4) than this (if electrolysis is continued, the pH of the system will drop somewhat). An aqueous solution containing bromide ions and ammonium ions has no activity unless electrolyzed, but becomes bleaching active through electrolysis and can be used as a bleaching solution.

Sufficient bleaching activity can be provided by using an amount of electricity of 96,500 clones or more per mole of silver in the sensitive material during electrolysis. The upper limit of this amount of electricity is determined by how many hours the bleaching process is to be carried out, and ultimately depends on the amount of the photosensitive material to be bleached. Next, regarding the material of the electrode used for electrolysis, the anode may be any electrically conductive material or semiconductor material that does not dissolve by electrolysis, such as carbon (which may be in the form of a plate or fiber), platinum, titanium, etc. alloy(
Synthetic components are Ti and others A4CrlFesMnlMO
(selected from metals such as 1). As the cathode, any corrosion-resistant and electrically conductive material may be used, but stainless steel (components include Fe, Cr, and N)
Selected from metals such as i. SUS32 is preferred. )
etc. are appropriate. The electrolytic cell may have a diaphragm, but it is not necessary. It is preferable to stir the solution during electrolysis. Appropriate current for electrolysis is about 0.1 to 20 A/Dm2.

Electricity should be passed within a range that does not cause an excessive rise in temperature due to heat generation. It is advantageous for the temperature of the electrolyzing solution to be approximately the same as that required for the bleaching solution. However, these temperatures do not have to be the same. The liquid obtained by electrolysis has only a pale yellow color and only a slight odor of ammonia, so there is no concern about pollution.

Ammonium ions, bromide ions and...buffers (
Any substance that can be used as a pH buffering agent for a bleaching solution can be used.

For example, any known material that can be used for this purpose can be used. ) When an aqueous solution consisting of The amount of active bromide also increases, but takes a saturated value. Therefore, the solution after electrolysis for a certain period of time contains a stable amount of oxidizing agent, and the pH and redox potential are also stable, so that a stable bleaching solution can be obtained. Further, after a certain period of time (for example, about one day) has passed after the electrolysis is stopped, the active bromide loses its bleaching edge and becomes bromide ions. When electrolysis is started again, active bromide is obtained, and the cycle can be repeated. That is, according to the present invention, a stable bleaching solution can be obtained by simply replenishing the bromide ions and ammonium ions lost in bleaching treatment and continuing electrolysis, and furthermore, the processing solution that has been deactivated after stopping electrolysis or after bleaching treatment can be discarded. However, it causes almost no environmental pollution. In addition to bromide ions, ammonium ions, and PH buffers, anticorrosive agents (eg, alkali metal salts of nitric acid (eg, sodium salts, potassium salts), ammonium salts, etc.) can also be present. Below, an apparatus for carrying out electrolysis in the method of the present invention will be explained.

First, a so-called "two-tank type" device (hereinafter referred to as "Embodiment 1") in which an electrolytic bath and a sensitive material processing bath are provided separately is introduced.
I will explain about it. The electrolytic cell consists of an anode, a cathode, and an electrolytic solution (bleaching solution), each connected to a DC power source, and may also be provided with stirring means (for example, a propeller).

On the other hand, the sensitive material processing tank is also a container equipped with a stirring means, and includes a pipe with a circulation pump installed in the middle (this is located relatively below the tank) and another pipe (this is located relatively above). It is connected to the electrolytic cell via two pipes. These two pipes allow the electrolyte (bleaching solution) to circulate between both tanks. A circulation pump may be installed in the middle of the upper pipe. [When electrolyzing an aqueous solution containing bromide ions and ammonium ions, the electrode reaction is 2Br at the anode.
-1Br2+2e and a reaction between the generated Br2 and M circle+ occurs, and at the cathode 2H++2e→H2, Br2+
2e→2Br-.

] One aspect of the shape of the electrode used is as follows. anode:
In order to prevent the generated Br2 from scattering before it reacts with NH4+, excess Br2 is reduced to Br- again.
In order to obtain a constant amount of oxidizing agent, the anode is placed below the cathode and parallel to the bottom of the electrolytic cell, with only the parallel surface serving as the conductive part, and the vertical part (conducting wire) being shielded with organic synthetic resin. ing. Cathode: In order to prevent the generated hydrogen gas from adsorbing to the electrode and increasing electrical resistance, it is not parallel to the bottom of the electrolytic cell, but has an inclination of about 45 mm, and grooves are provided on the surface to prevent the electrode from adsorbing. Facilitates the rise and desorption of hydrogen gas from

Next, an apparatus (embodiment 2) which also belongs to the two-tank type will be explained.

An aqueous solution containing bromide ions and equipped with an electrode (electrolytic cell) and an aqueous solution containing ammonium ions (sensitive material processing bath)
is separated through a porous partition wall, and the generated Br2 (
Similarly, H2 can be introduced through the partition wall into an aqueous solution containing ammonium ions to form a bleaching solution.

The partitions used in this method are continuous microporous partitions that do not allow ions to pass through but allow gases to pass through, and are made of, for example, poly(tetrafluoroethylene) or poly(tetrafluoroethylene) and polyethylene, polypropylene, polyvinyl chloride. It consists of a mixture with polymers such as.
In the latter case, the content of poly(tetrafluoroethylene) is preferably 50 percent or more. Average pore diameter is approximately 0.2~
100 microns is suitable, but 0.5 to 50 microns is preferred. The thickness of the partition wall is approximately 0.01~577111L
．． Preferably it is 0.1 to 2 m. Such porous partition walls are disclosed in Japanese Patent Application Laid-Open No. 46-7284 and Japanese Patent Publication No. 42-1356.
No. 0, Special Publication No. 49-41265, U.S. Patent No. 3,315
, No. 020 and No. 3,664,915. If the partition body is tubular, the inner diameter is approximately 0.4H!
l~10CT! L is suitable, but about 1 to 1071i!
It is preferred. When using this method, the pH of the electrolyte
is suitably 7 or less, but preferably about 5 to 7, and... of the aqueous solution containing ammonium ions is about 5 to 9.
．． A value of 5 is appropriate, and a value of 7.0 to 8.5 is particularly preferred. At this time, it is preferable that the electrolytic cell containing the electrolyte be sealed during electrolysis.By sealing it, it is possible to prevent the bad odor of Br2, etc., and also to prevent the inside of the electrolytic cell from being heated due to the generation of hydrogen gas. This is because it becomes a pressure state, which facilitates the passage of Br2 and hydrogen gas through the partition wall, and conversely prevents the reverse intrusion of ammonia gas.
As another embodiment, a tank type in which both tanks are combined is also possible.

In the case of a single-tank type, both electrodes may be perpendicular to the bottom of the tank, in which case stirring can be achieved from the top. The electrolytic cell, electrode shape, and sensitive material processing bath described above are representative embodiments of the present invention, and are not limited thereto.

The method of the present invention uses color negative film, color paper,
It can be applied to any processing of silver halide color photographic materials such as color positive films, color reversal films, and silver dye bleaching materials.

In the method of the present invention, the processing steps of the image-exposed color negative film, color positive film, color vapor, etc. are usually (1) stopping color development → bleaching, washing with water, constant fixing, washing with water, stabilizing, drying, (2) color development. It is based on the following steps: - stop - bleach - fix - wash - stabilize - dry; or (3) color development → stop and fix → bleach → fix - wash, wash, stabilize → dry.

In the steps (1) to (3), a pre-bath, hardening bath, etc. may be further provided before color development, and a stabilizing bath, washing with water after bleaching, etc. can be omitted. The processing steps for color reversal film are usually (4) black and white development, one stop, one water wash, one brush, one water wash, one color development, one stop, one water wash → bleaching, one water wash, one water set → water washing → stabilization and drying, or (5) black and white development. The basic process is one stop of development, one wash with water, then a brush, one wash with water, one stop of color development, one wash with water, one bleach, one wash with water, one stabilization, and one dry.

In steps (4) and (5), a pre-bath, a pre-dural bath, a neutralization bath, etc. can be further provided. Further, stable dissolution, washing with water after bleaching, etc. can be omitted. The force brush bath can be replaced by re-exposure, or the force brush bath can be omitted by adding a force brush agent to the color developer. Although the steps shown in (1) to (5) above are useful in the photographic processing method of the present invention, the present invention is not limited to these steps. The color developer used in the present invention has the composition of a general color developer containing an aromatic primary amine developing agent.

Preferred examples of aromatic primary amine color developing agents are p-phenylenediamine derivatives as shown below. N,N-diethyl-p-phenylenediamine, 2-amino-5-diethylaminotoluene, 2-amino-5-(N-ethyl-N-laurylamino)toluene, 4-[N-ethyl-
N-(β-hydroxyethyl)amino]aniline, 2-
Ethyl-4-[N-ethyl-N-(β-hydroxyethyl)amino]aniline, N-ethyl-N-(β-methanesulfamidoethyl)-3-methyl- as described in U.S. Pat. No. 2,193,015 4-Aminoaniline, US Patent 2,
N-(2-amino-5-diethylaminophenylethyl)methanesulfonamide described in No. 592,364, N,
N-dimethyl-p-phenylenediamine, U.S. Pat. No. 3,
4-amino-3-methyl-N-ethyl-N-methoxyethylaniline, 4-amino-3-methyl-N-ethyl-N-β-described in No. 656,950, No. 3,698,525, etc. Ethoxyethylaniline and 4-amino-
Preferred representative examples include 3-methyl-N-ethyl-N-β-butoxyethylaniline and salts thereof (eg, sulfate, hydrochloride, sulfite, p-toluenesulfonate, etc.).

The color developer may contain other known developer components. For example, as the alkaline agent or buffering agent, caustic soda, caustic potash, soda carbonate, potassium carbonate, tertiary sodium phosphate or potash, potassium metaphosate, silica sand, etc. may be used alone or in combination. In addition to the above additives, hydrogen phosphate 2.
Various salts are used, such as sodium or potassium, potassium or sodium dihydrogen phosphate, sodium or potassium bicarbonate, phosphoric acid, alkali nitrate, and alkali sulfate. If necessary, any development accelerator can be added to the color developing solution. For example, various pyridinium compounds and other cationic compounds represented by U.S. Patent No. 2,648,604, Japanese Patent Publication No. 44-9503, and U.S. Pat. Neutral salts such as thallium and potassium nitrate;
U.S. Patent No. 2,533,990, U.S. Patent No. 2,531,
No. 832, U.S. Patent No. 2,950,970, U.S. Patent No. 2
, 577.127, nonionic compounds such as polyethylene glycol and its derivatives, polythioethers, etc., Japanese Patent Publication No. 44-9509, Pelkey Patent No. 682,86
Organic solvents and organic amines (e.g. ethanolamine, ethylenediamine, diethanolamine) described in No. 2, etc.
In addition, L. F. A. “PhOtOgra” by MasOn
phicPrOcessigChemistry”P
4O~43 (FOcalPress-LOndO "19
66) can be used.
Other useful development accelerators include benzyl alcohol and phenylethyl alcohol as described in U.S. Pat. It is. In addition, sulfites commonly used as preservatives, such as sodium sulfite, potassium sulfite, potassium bisulfite, sodium bisulfite, hydroxylamine, ascorbic acid, pentose, hexose, etc., can be added.

In the present invention, any antifoggant can be added to the color developing solution if necessary.

Antifoggants include potassium bromide, sodium bromide,
Alkali metal halides such as potassium iodide and organic anticapriants can be used. Examples of organic antifoggants include nitrogen-containing heterocyclic compounds such as benzotriazole, 6-nitrobenzimidazole, 5-nitroisointazole, 5-methylbenzotriazole, 5-nitrobenzotriazole, and 5-chlorobenzotriazole;
Mercapto-substituted heterocyclic compounds such as -phenyl-5-mercaptotetrazole, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, and also mercapto-substituted aromatic compounds such as thiosalicylic acid can be used. Preferred are nitrogen-containing heterocyclic compounds, particularly preferred are nitrogen-containing heterocyclic compounds that are not mercapto-substituted. The amount of the antifoggant added is within the range of about 1 mσ to 5 t1, preferably 5 m7 to 1 t, per 1 t of color developing solution. Furthermore, polyphosphoric acid compounds represented by sodium hexametaphosphate, sodium tetrapolyphosphate, sodium tripolyphosphate, or potassium salts of the above polyphosphoric acids, phosphonocarboxylic acids, α-amino acids, ethylenediaminetetraacetic acid, nitrilotriacetic acid, and cyclohexanediaminetetraacetic acid. , iminodiacetic acid, N-hydroxymethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, and the like can be used as the water softener. The amount added varies depending on the hardness of the water used, but is usually about 0.5 to 1 t/t. Other calcium and magnesium pigments can also be used in photographic processing solutions. These are J. Will
``Belgische Chemi-Sc'' by lems
heIndustrie”, volume 21, page 325 (1
956) and Volume 23, page 1105 (1958). In the case of reversal color processing, competing couplers, force brushing agents and compensating developers may also be added to the color developer.

Citrazic acid, J acid, H acid, etc. are useful as competitive couplers.

For example, U.S. Patent No. 2,742,832,
No. 9504, No. 44-9506, No. 44-9507, U.S. Pat. No. 3,520,690, U.S. Patent No. 3,560,21
Compounds described in No. 2, No. 3,645,737, etc. can be used. Power brushing agents include alkali metal borohydride (e.g. sodium borohydride), amine borane (e.g. t-butylamine borane), tin-aminopolycarboxylic acid complex, tin-pyrophosphate complex, tin-tetrapolyphosphate complex, tin-hexamethalin. Acid complex salts, ethylenediamine, etc. can be used.

Other compounds described in Japanese Patent Publication No. 47-38,816 are also useful. Compensation developers include p-aminophenol, N-benzyl-p-aminophenol, 1-aminophenol,
Phenyl-3-pyrazolidone and the like can be used.

Others, such as Special Publication No. 45-41,475, No. 46-
Compounds described in No. 19,037 are also useful. The value of the color developer is in the range of about 7 to 14, particularly preferably in the range of about 8 to 13.

The processing method of the present invention is suitable for color photography in which dye-forming couplers are included in the light-sensitive material, such as U.S. Pat.
No. 2,027, No. 2,376,679, No. 2,801
, 171, as well as color photography methods in which color formers are included in the developer, such as U.S. Pat.
, 252,718, 2,590,970, and 2,592,243.

However, at present, the former method is mainly used.

When a dye-forming coupler is included in a light-sensitive material, a multilayer light-sensitive material is generally used, in which the coupler remains in a given layer and does not diffuse into other layers during manufacturing, storage, and processing steps. This is desirable. As the fixer, one having a commonly used composition can be used.

As a fixing agent, thiosulfates, thiocyanates, thioureas, thioglycols, water-soluble organic diols containing sulfur and oxygen in the molecule (for example, 3,6-dithia-1,
8-octyldiol) and the like. In addition to the fixing agent, the fixing solution contains stabilizers such as sulfites (e.g., sodium sulfite) (especially preferred when thiosulfate is used as the fixing agent), buffering salts, etc. Swell-inhibiting salts (eg, hardeners such as potash alum) may be included. In addition, the black and white developer used in silver dye bleaching and reversal color photography can contain commonly used developing agents.

As developing agents, dihydroxybenzenes (e.g. hydroquinone, sodium hydroquinone monosulfonate), 3-pyrazolidones (e.g. 1-phenyl-3
-pyrazolidones), aminophenols (e.g. N-
(methyl-p-aminophenol), ascorbic acid, etc. can be used alone or in combination.
Developing solutions generally contain preservatives, alkaline agents, buffering agents, etc.
Contains anti-fogging agents, and if necessary, solubilizing agents,
It may also contain toning agents, development accelerators, surfactants, defoamers, water softeners, hardeners, tackifiers, etc. (the details of these additives are well known in the art). .
The stabilizing bath contains an image stabilizer (depending on the target color photosensitive material).
(e.g. formaldehyde), surfactants (e.g. polyethylene oxide), hardeners (e.g. potassium alum), UV blowing agents (e.g. bistriacylaminostilbenes), mold inhibitors (e.g. sodium benzoate), buffering agents, etc. But that's fine. In carrying out photographic processing in accordance with the present invention, all processing temperatures are approximately 20 to 7
The temperature may be set appropriately within the range of 0°C, but the range of 25 to 60°C is preferable.

When couplers are used in the practice of this invention, the couplers can be either four-equivalent couplers or two-equivalent couplers. Further, at least a part thereof may be a dynamic coupler for color correction, a colorless coupler, or a coupler that releases a development inhibitor during development (so-called DIR coupler). As the yellow coupler, an open chain ketomethylene coupler can be used. Among these, benzoylacetanilide and pivaloylacetanilide compounds are advantageous. Specific examples of yellow couplers that can be used include U.S. Pat.
No. 506, No. 3,0408,194, No. 3,551,
No. 155, No. 3,582,322, No. 3,725,0
No. 72, No. 3,894,875, West German Patent Publication 1,5
No. 47,868, West German patent application (0LS) 2,213,
No. 461, No. 2,219,917, No. 2,261,3
No. 61, No. 2,263,875, No. 2,414,00
There are some listed in No. 6, etc. As the magenta coloring coupler, 5-pyrazolone compounds are mainly used, but intazolone compounds and cyanoacetyl compounds can also be used. Examples are U.S. Patents 2,600,788, 2,983,608, 3,062,653,
, No. 127,269, No. 3,311,476, No. 3,
No. 419,391, No. 3,476,560, No. 3,5
No. 19,429, No. 3,558,319, No. 3,58
No. 2,322, No. 3,615,506, West German patent 1,
No. 810,464, West German Patent Application (0LS) 2,408
, No. 665, No. 2,418,959, No. 2,424,
No. 467, Special Publication No. 40-6031, No. 44-2016
This is what is written in the issue. Phenol or naphthol derivatives are mainly used as cyan color-forming couplers. Specific examples include U.S. Pat.
, No. 521,908, No. 2,895,826, No. 3,
No. 034,892, No. 3,311,476, No. 3,3
No. 86,830, No. 3,458,315, No. 3,47
No. 6,563, No. 3,583,971, No. 3,591
, No. 383, and JP-A-48-78905. In addition, specific examples of DIR couplers and other [compounds that release development-inhibiting compounds] include U.S. Patent No. 3,227,554, U.S. Pat. , No. 701, 783, 3
, 790,384, British Patent No. 953,454, West German Patent Application (0LS) No. 2,414,006, 0LS No. 2,41
No. 7,914, No. 2,417,945, No. 2,454
, No. 301, No. 2,454,329, U.S. Patent No. 3,2
It is described in No. 97,445, No. 3,379,529, etc.

In addition, JP-A-51-102636, JP-A No. 26541, JP-A-50-159336, JP-A-51-20826, JP-A-51-26034, Japanese Patent Application No. 114,445/1983,
No. 50-1,792, No. 50-70,592, No. 5
No. 0-96,435, No. 50-118,029, No. 5
Couplers described in each specification of No. 0-118,540 can also be used.

Two or more types of the above-mentioned couplers can be used in the same layer in order to satisfy the characteristics required of a photosensitive material, and the same coupler can of course be added to two or more different layers.

These couplers are generally dispersed in the silver halide photographic emulsion layer with a solvent of appropriate polarity. Useful solvents are tri-0-cresyl phosphate, trihexyl phosphate, dioctyl butyl phosphate, dibutyl phthalate, diethyl laurylamide, 2,4-diallylphenol, octyl benzoate, and the like. Typical color image forming substances for the silver dye bleaching photosensitive material processed in the present invention include, for example, azo dyes.

A color light-sensitive material to be photographically processed by the method of the present invention has at least one silver halide emulsion layer on a support. Usually, a red-sensitive silver halide emulsion layer, a red-sensitive silver halide emulsion layer,
It has a green-sensitive silver halide emulsion layer and a blue-sensitive silver halide emulsion layer.

More specifically, a support typically contains a red-sensitive silver halide emulsion layer containing a cyan image-forming coupler, a green-sensitive silver halide emulsion layer containing a magenta image-forming coupler, and a yellow image-forming coupler. Each has at least one blue-sensitive silver halide emulsion layer. Such photographic elements may have non-light sensitive photographic layers such as antihalation layers, interlayers to prevent color mixing, etc., yellow filter layers, protective layers, etc. Furthermore, there is no particular restriction on the order in which the red-sensitive layer, green-sensitive layer, and blue-sensitive layer are arranged. Silver halide photographic emulsions, whether surface latent image type or internal latent image type, can be used, and those manufactured according to conventionally known methods can be used. As explained above in detail, there are no particular limitations on the method for producing the silver halide emulsion of the light-sensitive material used in the present invention, the layer structure, photographic additives, photographic materials, photographic processing liquid, etc.

By applying the bleaching method of the present invention, the following advantages can be obtained.

(1) Environmental pollution is negligible.

(a) If the bleaching solution is left for about a day after use, the oxidizing power will be almost gone and the wastewater will not contain any compounds that cause environmental pollution.

(b) Bleach solution is almost neutral and does not require adjustment when disposed of.

(c) The bleaching solution is almost colorless and does not cause environmental pollution due to coloring even if it is discarded.

(Conventional bleaching solutions are brown in color.) (2) Liquid management is easy.

Activation and stopping of electrolysis can be easily and automatically achieved through control using at least one of a PH meter and a potentiometer.

Therefore, a secondary effect is obtained in that the use of a PH buffer is not essential. (3) Sufficient color density can be obtained.

When conventional bleaching agents (e.g., Fe-EDTA complexes) are used, the reaction product between the oxidized color developer and the coupler is not sufficiently oxidized to the dye state and remains in the leuco state, resulting in only a low color density. However, in this method, the oxidizing power is moderately strong and sufficient color density can be obtained.

(4) It is inexpensive.

All the reagents used in the bleaching solution are inexpensive, and the electrolytic device has a simple structure and is sufficiently effective and inexpensive.

(5) No stain occurs on the processed photosensitive material.

No iron stains occur because no iron compounds are used as bleaching agents. (6) Bleaching is rapid.

A bleaching rate equivalent to that of known bleaching solutions (for example, bleaching solutions in which the bleaching agent is a complex salt of an aminopolycarboxylic acid and ferric iron, a ferric salt, or a ferrician iron salt) can be obtained.

Examples Single-layer films in which a blue-sensitized silver iodobromide gelatin emulsion, a green-sensitized silver iodobromide gelatin emulsion, and a red-sensitized silver iodobromide gelatin emulsion were coated on a cellulose triacetate support were prepared as shown below. The treatment process and treatment solution [Formulation A and B (pre-electrolysis solution)] were used to compare the difference in effectiveness between the known bleaching solution and the present bleaching solution.

Since this test was conducted to examine the bleaching effect, it was not necessary to carry out the test in a dark room, and all treatments were carried out in a bright room. The method for preparing the bleaching solution is as follows.

The liquid composition before electrolysis was ammonium bromide 120t/t1 boric acid 8f/t1 borax (decahydrate) 3f/TSPH8. O
(Liquid temperature: approximately 25°C).

700 mt of this solution is put into the electrolytic cell and sensitive material processing tank in the apparatus of Embodiment 1 described above. Next, the liquid is stirred by propellers (stirring means) provided in both tanks, and at the same time, the liquid is circulated by a pump. Next, direct current is applied to both poles from the power source to begin electrolysis. As electrode materials, the anode is Carbo 7 fiber (polyvinyl chloride resin was used as the support), and the cathode is SUS3.
2 stainless steel was used. The electrolytic conditions were a current of 1 A (cathode current density of about 4.5 A/Dm2).

The anode current density was not determined because the surface area of the carbon fiber of the anode material was not easily determined. ), the voltage at this time was about 3 to 3.2. The flow rate was about 10t/Hr. The prescription solution before electrolysis has no bleaching ability.

The voltage, ..., RedOx potential (versus saturated calomel electrode), temperature, and amount of active bromine (in terms of Br) associated with electrolysis time (quantity of electricity) are shown in Table 1 below.

The decrease in value due to electrolysis is thought to be due to the scattering of ammonia and the production of Br2 (including the destruction of NH3).

It is believed that the temperature increase is due to the heat of reaction between ammonia and Br2. The reason why the amount of active bromine does not increase in spite of the increase in the amount of electricity is thought to be due to the cathodic reaction of Br2+2e-$2Br- and the reaction of Br2 with ammonia ions to form bromide ions. The fact that the amount of active bromine does not increase in this way is very convenient in terms of liquid management. From the values in Table 1, it can be seen that the solution obtained by electrolysis for at least 10 minutes has a sufficient bleaching edge and is effective as a bleaching solution.

Each silver halide emulsion used in the test was prepared by a conventional method, but for reference, the types of couplers and silver halide used as main materials, and the amounts used thereof are listed.

The processing steps were the same as step A except that bleaching was carried out at 29.4°C.

The treatment solution composition was A, except that the bleaching solution was as shown below.
Same composition as . The results obtained are shown in the table below.

As is clear from the values in the table above, it can be seen that when bleaching with the B formulation of the present invention, a higher color density is obtained than with the A formulation, and good results are obtained in that the residual silver is low.

Moreover, the B formulation according to the present invention provided various advantages ((1) to (6) listed above) that were not obtained with the A formulation. These results were also the same in the processing of multilayer color sensitive materials.

Claims (1)

[Scope of Claims] 1. A method of bleaching an exposed silver halide color photographic light-sensitive material using a bleaching solution after development, the bleaching solution comprising:
Bleaching obtained by coexisting bromine generated by electrolyzing an aqueous solution containing a water-soluble bromine-containing compound that generates bromine through electrolytic oxidation and ammonium ions in an aqueous solution (either an electrolytic solution or a photosensitive material processing solution). A bleaching method for color photographic materials characterized by using an active aqueous solution. 2. Claim 1, characterized in that the bleaching solution is a bleaching active aqueous solution obtained by electrolyzing an aqueous solution containing ammonium ions and a water-soluble bromine-containing compound that generates bromine through electrolytic oxidation. bleaching treatment method.