JPH0136094B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for photographically processing silver halide photographic materials, and particularly to a method for fixing silver halide color photographic materials which have good stability, excellent processing efficiency, and can cause negligible environmental pollution. More specifically, silver can be easily recovered, and even when recycled, it does not deteriorate and can be recycled without being discarded by adding a regenerating agent or replenisher as necessary. The present invention relates to a bleach-fixing method for silver halide color photographic materials that can be recycled and used repeatedly, and environmental pollution caused by wastewater can be ignored. A color image is obtained by developing an exposed silver halide color photographic light-sensitive material, followed by bleaching and fixing. In this case, a processing method in which bleaching and fixing are performed separately (bleach-fixing) There is a processing method (bleach-fixing process) in which both processes are performed simultaneously. In other words, in the bleach-fixing process, the image silver developed in the color development process is bleached and converted into soluble salts, and then in the fixing process, all the soluble silver salts are dissolved and removed to desilver and obtain a color image. It will be done. On the other hand, in the bleach-fixing process, the image silver is bleached in the presence of a fixing agent, fixing is also performed, and the silver is desilvered to obtain a color image. Therefore, it has been desired to perform a bleach-fixing process because it is superior in simplifying and speeding up the process compared to a bleach-fixing process. In response to this demand, bleach-fix solutions were developed and used. Bleaching agents used in conventional bleach-fix solutions usually include ferric complex salts, typical examples of which include red blood salt and ethylenediaminetetraacetic acid iron () ammonium salt. However, if these complex salts are mixed into wastewater, they cause environmental pollution, and in order to prevent this, it is necessary to recover the used bleach, and furthermore, when recovering silver from the bleach-fix solution, it is necessary to collect iron ions. There were problems such as complicated processing. On the other hand, there is a method using persulfuric acid as a bleaching agent (US Pat. No. 3,772,020) or a method using bromine and ammonium ions generated by electrolysis (Japanese Patent Laid-Open No. 116,830/1989).
New bleaching methods have been proposed to reduce environmental pollution. However, none of these methods can be used in combination with a fixing agent (for example, sodium thiosulfate) and cannot be used in bleach-fixing processes. For this reason, there has been a strong desire to develop an excellent bleach-fixing method that does not pollute the environment. A first object of the present invention is to provide a bleach-fixing method for 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 and fixing color photographic materials in which silver in a bleach-fixing solution can be easily recovered using electrolysis or other silver recovery methods. A third object of the present invention is to dispose of all of the bleach-fixing solution by simply replenishing it with new bleach-fixing solution (regenerating agent or replenisher) and improving the bleach-fixing performance when it is used repeatedly after silver is recovered. It is an object of the present invention to provide a bleach-fixing method for color photographic materials that can be recycled and used repeatedly without having to be recycled. A fourth object of the present invention is that the bleach-fixing solution used is highly stable, does not deteriorate in bleach-fixing performance even when recycled and used over a long period of time, or is stored for a long period of time, and is inexpensive. An object of the present invention is to provide an economical rapid bleach-fixing method for color photographic materials. An object of the present invention is to provide a method of bleach-fixing an exposed silver halide color photographic light-sensitive material using a bleach-fixing solution after developing the exposed silver halide color photographic material.
A bleach-fix solution containing mol/mol of iodide ions and at least 0.17 mol/silver halide fixing agent, substantially free of metal salts of polycarboxylic acids or aminopolycarboxylic acids, and having a pH of 7 or less. This is achieved by using The iodide used in the present invention to contain iodide ions has the following general formula ()
It is indicated by. General formula () I ^- _o M ⁿ⁺ In the formula, M ⁿ⁺ is an alkali metal ion (for example, each ion such as potassium, sodium, etc., in which case n = 1),
It represents an alkaline earth metal ion (for example, each ion such as magnesium or calcium, in which case n=2) or an ammonium ion represented by the following general formula (in which case n=1). General formula () In the formula, R ₅ , R ₆ , R ₇ and R ₈ are hydrogen atoms, alkyl groups (for example, methyl groups, ethyl groups, etc.), aryl groups (for example, phenyl groups, 2-quinolyl groups, etc.), aralkyl groups ( For example, it represents a benzyl group). Further, R ₅ , R ₆ and R ₇ may jointly form a 5- to 6-membered aromatic ring (for example, each aromatic ring such as a pyrrole ring or a pyridine ring). Preferably, M ⁿ⁺ is an alkali metal ion (for example, potassium, sodium, etc. ions) or an ammonium ion represented by the general formula (),
More preferable M ⁿ⁺ is an ammonium ion represented by the general formula (), and among these ammonium ions, R ₅ , R ₇ and R ₈ are particularly preferable from the viewpoint of the processability of hydrogen atoms. These iodides can be used alone or in combination of two or more, and when used in combination, the mixing ratio of the combinations is arbitrary. The iodide ions of the present invention are required to be contained in an amount of at least 1.7 mol/mole, so that the above-mentioned objects of the present invention can be fully achieved, but it is particularly desirable to maintain the viscosity of the solution low and to maintain the content of the bleach-fix solution. In order to maintain a high diffusion rate and increase processing efficiency, the iodide ion concentration is preferably from 2 mol to 6 mol/. The silver halide fixing agent used in the present invention is a compound that reacts with silver halide to form a water-soluble complex salt, such as potassium thiosulfate, sodium thiosulfate, and ammonium thiosulfate, which are used in ordinary fixing processes. thiosulfates, potassium thiocyanate, sodium thiocyanate,
Typical examples include thiocyanate thioureas such as ammonium thiocyanate. Also,
These fixing agents can be used alone or in a suitable combination of two or more, and when used in combination, the mixing ratio of the combination is arbitrary. Among these fixing agents, thiosulfates and thioureas are preferred, and it is particularly preferred to use ammonium thiosulfate and thiourea in combination. Although alkali metal or ammonium halides may exhibit a fixing effect, the silver halide fixing agent of the present invention is defined herein as not containing these halides. The fixing agent of the present invention is required to be contained in an amount of at least 0.17 mol/mole, so that the above-mentioned objects of the present invention can be fully achieved, but it is particularly desirable to maintain the viscosity of the bleach-fixing solution low and to In order to maintain a high liquid diffusion rate and increase processing efficiency, the amount is preferably 0.5 mol to 1.8 mol/. As mentioned above, in the present invention, the fixing agent may be mixed and contained, but in this case, depending on the amount of the combination, the total amount is at least
It is sufficient if the content is 0.17 mol/. Further, when using thiosulfate, it is preferable to add sulfite (for example, ammonium sulfite, sodium sulfite, etc.) as a stabilizer. The amount added is preferably about 1/10 of the amount of thiosulfate. The thiourea fixing agent that can be used in the present invention is represented by the following general formula (). In the formula, R ₁ , R ₂ , R ₃ and R ₄ each represent a hydrogen atom, an alkyl group which may have a substituent, an aryl group, an aralkyl group, a carbamoyl group, a thiocarbamoyl group, an amino group, and R ₁ and R ₂ or
R ₃ and R ₄ , R ₁ and R ₃ , or R ₂ and R ₄ may each work together to form a 5- to 6-membered ring. _R1 ,
Examples of substituents that can be substituted for each group of R ₂ , R ₃ and R ₄ include a carboxy group, a sulfo group, an amino group, a nitro group, an alkyl group, and a hydroxy group. Preferably, R ₁ to R ₄ represent a hydrogen atom, an alkyl group which may have a substituent, or an amino group. More specifically, thiourea, N-methylthiourea,
N,N-dimethylthiourea, N,N,N',N'-
Examples include tetramethylurea and thiosemicarbazide, with thiourea being particularly effective. The bleach-fixing solution according to the present invention is required to be used at a pH of 7 or lower, so that the above-mentioned objects of the present invention can be fully achieved.
It is preferable to use it in the range of 2.5 to 6.5. The bleach-fixing method of the present invention uses a bleach-fixing solution having the above-mentioned composition, and an oxidizing agent that can coexist with the fixing agent may be added as a further compound.
Typical oxidizing agents include nitro compounds (e.g. m-nitrobenzenesulfonic acid, 2-
Nitro-4-sulfobenzoic acid, etc., quinones (e.g. p-benzoquinone, 5,8-quinolinedione, etc.), free radical nitroxy compounds (e.g. 2,2,5,5-tetramethyl-1-pyrrolidinyl-oxy- 3-carboxylic acid, etc.).
It was found that the bleach-fixing ability was clearly improved by adding these compounds. The bleach-fixing method of the present invention is characterized in that it contains a large amount of iodide ions and a silver halide fixing agent, and has a pH of 7 or less. Conventionally, an aqueous solution of potassium iodide and sodium thiosulfate has been used as a reducing solution for silver images. The action of this force-reducing liquid was mild, and it was used for slight force reduction. This is described, for example, in the photo positive painting method, written by Goro Miyamoto (Hirokawa Shoten). However, it goes without saying that it is completely impossible to bleach-fix a color photosensitive material using this reducing solution. This was achieved for the first time by using a solution containing a fixing agent and having a pH of 7 or less. Although it cannot be said to be an exact value, when measuring the time to complete bleach-fixing (clearing time), the bleach-fixing method of the present invention is shortened to about one tens of thousands to one millionth of the time compared to the reducing solution. ing. The iodide and silver halide fixing agents used in the bleach-fixing method of the present invention are both very common compounds and can be easily obtained, and are also inexpensive, making them an economically superior bleach-fixing solution. This makes it possible to supply Furthermore, the bleach-fixing solution according to the present invention is similar to the conventional second bleach-fixing solution.
Unlike bleach-fix solutions that use iron ions, the silver ions dissolved in the solution can be easily recovered and the solution has extremely good stability, so after recovering the silver ions, it can be recycled as needed. After adding a replenisher or a replenisher to improve the bleach-fixing ability, it can be used repeatedly. As the method for recovering silver from a bleach-fix solution according to the present invention, any method conventionally known as a method for recovering silver from a fix solution can be adopted. Typical examples include silver precipitation using a precipitant;
Examples include an electrolytic method using electrolysis, a metal replacement method using ionization tendency, an exchange method using an ion exchange resin, etc. In the present invention, the electrolytic method is particularly preferred for repeated use in regenerating the liquid. Regarding the recovery method of these silvers, M.L. Schlebe (M.L.
Present status of Silver Recovery Motion Picture Your Laboratories
silver recovery motion picture Laboratories)
It is described in Vol. 74, pp. 505-514 (1965). Next, the present invention will be illustrated with reference to Examples, but the embodiments of the present invention are not limited thereto. Example 1 Commercially available Sakura color paper was passed through a step wedge and subjected to decomposition exposure, developed using Conidor X (monochrome developer) at 20°C for 4 minutes, washed with water, and dried to obtain a monochrome silver image. The maximum density of the red sensitive layer at that time was 0.92. The above sample was immersed in a bleach-fixing solution of each composition shown in Table 1 below, and the time required to complete bleach-fixing (clearing time) until the silver image in the red-sensitive layer of the sample was dissolved to become a white background was measured. . The temperature was 34°C in all cases.

[Table] Each sample No. 1 to 8 was diluted with water.
shall be. In Table 1, Samples No. 3 to 7 are of the bleach-fixing method of the present invention, and Samples No. 1, 2, 8, and 9 are of a method other than the present invention. Furthermore, sample No. 10 was obtained by a commonly used known bleach-fixing method. As is clear from Table 1, the bleach-fixing method of the present invention has a bleach-fixing completion time (clearing time) within a range that can be adapted to the bleach-fixing time normally used for color paper, that is, within 90 seconds. The object of the invention is achieved. In addition, on the white background of sample No. 8, a paper obtained by a commonly used known bleach-fixing method, yellowish brown color staining (probably caused by silver sulfide) remains imagewise. However, no color staining was observed on the white background of the paper obtained by the bleach-fixing method of the present invention. This suggests that when obtaining a color image, a highly pure color image with less color contamination can be obtained. Example 2 Using the same sample as in Example 1 and using a bleach-fixing solution with each composition shown in Table 2, the bleach-fixing time (clearing time) until the silver salt in the red-sensitive layer dissolves to form a white background was measured. ) was measured. The temperature was 34°C in all cases.

[Table] Samples Nos. 11 to 17 were all diluted with water, and after adjusting the pH to 4.0, 10 ml of a 0.5% silver sulfate aqueous solution was added. The Ag potential was measured before paper processing (clearing time measurement) using a saturated calomel electrode (model HC-205 manufactured by Toa Denpa) as a reference electrode and a PH meter HM-5A manufactured by Toa Denpa together with the Ag electrode. (Samples Nos. 12, 15, 16 and 17 can be said to be almost the same as Samples Nos. 2, 3, 4 and 5 of Example 1, respectively. Samples Nos. 11 to 14 are outside the scope of the present invention. ) The results of Example 2 are expressed as shown in Figure 1 by taking the logarithm of the clearing time (in seconds) on the vertical axis and taking the Ag potential on the horizontal axis. From Figure 1, it is clear that there is a linear relationship between the silver potential and the logarithm of the clearing time. For example, it contains 250g of ammonium thiosulfate and 25g of ammonium sulfite per unit, PH=4,
If the time of 0 is Condition-C, the clearing time can be made within 90 seconds by setting the silver potential at Condition-C to -492 mV or less as shown in Example 2, and the present invention objectives are achieved. In addition, this can be cleared by using additives other than those used in Example 2 (for example, ammonium bromide, ammonium iodide, and thiourea) to lower the silver potential to -492 mV or less during condition-C. It suggests that ring time can be reduced to under 90 seconds. Example 3 Commercially available Sakura color paper was passed through a step wedge, subjected to decomposition exposure, and then processed according to the following steps and processing recipe.

[Color photographic developer]

Benzyl alcohol 5.0ml Sodium hexametaphosphate 3.00g Anhydrous sodium sulfite 1.85g Sodium bromide 1.40g Potassium bromide 0.50g Boric acid (Na ₂ B ₄ O ₇・10H ₂ O) 39.10 g N-ethyl-N-[2-( Methanesulfonamide ethyl)]-3-methyl-4-aminoaniline sulfate 4.50g Add water to make up to 1, and add sodium hydroxide to
The pH was adjusted to 10.3. [Bleach-fix solution]-A Ethylenediaminetetraacetate iron ammonium
61.0g Ethylenediaminetetraacetate-2-ammonium 5.0g Ammonium thiosulfate 124.5g Sodium metabisulfite 13.3g Sodium sulfite 2.7g Water was added to bring the mixture to 1, and the pH was adjusted to 6.5. [Bleach-fix solution]-B Ammonium iodide 800g Ammonium thiosulfate 250g Ammonium sulfite 25g Water was added to make the solution 1, and the pH was adjusted to 4.0 with acetic acid. Processing step-A is a known and commonly used bleach-fixing method used for comparison, and processing step-B is a bleach-fixing method of the present invention. Table 3 shows the fog and maximum density of the color images obtained in each step.

[Table] From the table, it can be seen that the bleach-fixing method of the present invention using a conventional bleach-fixing solution that does not use compounds that cause environmental pollution produces sufficient bleach-fixing effects as in the conventional method. Furthermore, although color images with excellent transparency were obtained in each process, the color images obtained in processing step-B clearly had less contamination on the white background (as seen in the reduction in fog) and had high color purity. It was hot. When [bleach-fix solution]-B was left to stand for 30 days and then subjected to the same treatment, the same results as shown in Table 3 were obtained. This shows that the bleach-fixing performance is stable even when stored for a long time without deterioration.

Claims (1)

[Claims] 1. In a method in which an exposed silver halide color photographic light-sensitive material is developed and then bleach-fixed using a bleach-fix solution, the bleach-fix solution has a concentration of at least 1.7
Contains mol/mol of iodide ions and at least 0.17 mol/silver halide fixing agent, substantially does not contain metal salts of polycarboxylic acids or aminopolycarboxylic acids, and has a pH of 7 or less A bleach-fixing method for silver halide color photographic materials.