JP2000194089A - Heat developable photosensitive material and method for recovering silver from waste solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate a substrate and a coating film from a heat developable photosensitive material and to recycle silver and the substrate. SOLUTION: Silver is recovered from a heat developable photosensitive material with at least a photosensitive layer and a protective layer on at least one side of the substrate by using an organic solvent selected from hydrocarbon, alcohol, ketone and ester solvents, a mixed solvent selected from hydrocarbon and alcohol mixed solvents or a mixed solvent comprising the organic solvent and water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solution in which a silver compound obtained by separating a support of a photothermographic material and a coating film of a photosensitive layer and subjecting the coating film of the photosensitive layer to a solvent is dispersed, or a photothermographic material. The present invention relates to a method for efficiently recovering silver from a waste solution containing a silver compound generated during the production of silver.

[0002]

2. Description of the Related Art Conventionally, silver has been recovered from a silver halide photographic light-sensitive material when a coating film is peeled off from a support, since a main binder is gelatin, a strong base solvent (eg, potassium hydroxide, sodium hydroxide) is used. Etc.). In the case of the waste solution, since the solvent was water, silver could be recovered by an electrolytic oxidation method, an ion exchange method, a reverse osmosis method, a physicochemical treatment method, a biological treatment method, or the like.

However, in the case of a photothermographic material,
The binder of the coating film applied on the support was very poorly soluble in strong acids and strong bases, and it was difficult to peel and separate the coating film from the support in an aqueous solvent system. In addition, the coating film was difficult to decompose in biological treatment.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for easily recovering silver from a photothermographic material, wherein the separated silver, the solvent used for the separation and the separated silver are used. The purpose is to make effective use of supports and the like to reduce costs and reduce environmental problems.

[0005]

When silver is recovered from a photothermographic material, it is necessary to first peel off the coating from the support, and in order to dissolve the binder in the coating, the main solvent is water. However, it was necessary to use an organic solvent system. The coating film is dissolved or swelled and separated from the support of the photothermographic material by using the following specific organic solvent, silver is recovered from the separated coating solution, and cost reduction and environmental problems due to resource reuse. At the same time.

The above problem has been solved by the following method.

[0007] 1. In a photothermographic material having a photosensitive layer and a protective layer on at least one of the supports, a hydrocarbon-based material,
One kind of an organic solvent selected from alcohols, ketones and esters, a mixed solvent selected from hydrocarbons and alcohols, or a mixed solvent of the organic solvent and water is used. A method for recovering silver from a developed photosensitive material.

[0008] 2. The silver according to the above 1, wherein the hydrocarbon solvent is any one of octane, o-xylene, m-xylene, p-xylene, cyclohexane, cyclopentane, dipentene, methylcyclohexane, and methylcyclopentane. Collection method.

3. 2. The method according to the above 1, wherein the alcohol solvent is any one of methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, sec-butyl alcohol, ter-butyl alcohol, and allyl alcohol. Silver recovery method.

[0010] 4. The ester solvent is methyl formate, ethyl formate, propyl formate, butyl formate, isobutyl formate, isoamyl formate, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, s-butyl acetate,
2. The method of claim 1, wherein the method is any one of isobutyl acetate, isoamyl acetate, and allyl acetate.

5. Wherein the ketone solvent is any one of acetone, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, methyl isobutyl ketone, methyl amyl ketone, diethyl ketone, dipropyl ketone, diisopropyl ketone, and diisobutyl ketone. The silver recovery method as described.

6. 2. The method for recovering silver from a photothermographic material according to the above item 1, wherein the mixed solvent is any one of a mixed solvent of ethanol and toluene, isopropyl alcohol and xylene, and butyl alcohol and solvent naphtha.

7. 2. The method for recovering silver from a photothermographic material according to the above item 1, wherein the weight ratio of water of the mixed solvent of the organic solvent and water is 80% or less.

8. The method according to any one of 1 to 7, wherein the support and the coating film are separated from the photothermographic material, the solvent is recovered from the separated coating solution, and then silver is recovered from the residue. Characterized silver recovery method.

9. The support and the coating film are separated from the photothermographic material using the solvent according to any one of the above items 1 to 7, the separated coating solution is incinerated, and silver is recovered from the obtained residual ash. A method for recovering silver, comprising:

10. The support and the coating film are separated from the photothermographic material using the solvent according to any one of 1 to 7,
A silver recovery method comprising recovering a solvent from a separated coating solution and then recovering silver from residual ash obtained by incinerating the residue.

11. The support and the coating film are separated from the photothermographic material using the solvent according to any one of 1 to 7,
11. The silver recovery method according to any one of the above items 8 to 10, wherein silver is recovered from a mixed solution obtained by adding a waste solution generated from a process of manufacturing the photothermographic material to the separated coating solution. .

[12] 12. The silver recovery method according to any one of 1 to 11, wherein the silver recovery method is a bluing method.

Hereinafter, the present invention will be described in detail.

As described above, the photothermographic material is difficult to separate the photosensitive coating film from the support by treatment with an acid or alkali, and there is no other method than disposal or incineration. The above-mentioned method makes it possible to recover silver from the photothermographic material. Further, by reusing the separated support and recycling the used solvent, effective use of resources and reduction of environmental impact are reduced. It was something that could be done.

Various waste liquids are generated from the process of producing a photothermographic material. Among them, a waste liquid containing silver may be generated as a solvent-based solution. It is called a waste solution generated in the process of manufacturing the photosensitive material.

As a method for recovering silver, any method can be used as long as it can obtain purified silver. For example, a bluing method, a by-product recovery method, a calomel method (amalgam method) and the like are generally widely used. Used.

The photothermographic material usually has the following structure.

On the support, there is provided a photosensitive coating containing an organic silver salt, a photosensitive silver halide and a reducing agent for reducing the organic silver salt and a binder, and if necessary, a protective layer, a backing layer, and an undercoat. Layers are made.

Silver halide used in the photothermographic material functions as an optical sensor. The halogen composition is not particularly limited, and various types such as silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide, silver iodide and the like can be used. Usually, silver halide is contained in an amount of 0.75 to 30% by weight based on the organic silver salt.

The organic silver salt is a reducible silver source, and is an organic acid containing a reducible silver ion source. Examples of the organic acid include an aliphatic carboxylic acid, a carbocyclic carboxylic acid, a heterocyclic carboxylic acid, and a heterocyclic compound.
An aliphatic carboxylic acid having 0 to 30, preferably 15 to 25 carbon atoms) and a heterocyclic carboxylic acid having a nitrogen-containing heterocyclic ring are preferably used.

Examples of the silver salt of an organic acid include Research.
h Disclosure Nos. 17029 and 29963
And the following: silver salts of fatty acids (eg, gallic acid, oxalic acid, behenic acid, arachidic acid,
Silver salts such as stearic acid, palmitic acid and lauric acid);
Silver carboxyalkylthiourea salt (for example, 1- (3
-Carboxypropyl) thiourea, 1- (3-carboxypropyl) -3,3-dimethylthiourea, etc.); silver complexes of polymerization products of aldehydes with hydroxy-substituted aromatic carboxylic acids (for example, aldehydes (formaldehyde, formaldehyde, Acetaldehyde, butyraldehyde, etc.) and a hydroxy-substituted aromatic carboxylic acid (eg, a silver complex of a polymerization reaction product of salicylic acid, benzoic acid, 3,5-dihydroxybenzoic acid, 5,5-thiodisalicylic acid, etc.), Silver salts or complexes of thiones (eg, 3- (2-carboxyethyl) -4-hydroxymethyl-4-thiazoline-
2-thione and 3-carboxymethyl-4-thiazoline-2-thione), imidazole, pyrazole, urazole, 1,2,4-thiazole and 1H-tetrazole, 3-amino-5-benzylthio-1,2,4 -Complexes or salts of silver and nitrogen acids selected from triazoles and benzotriazoles; silver salts such as saccharin and 5-chlorosalicylaldoxime; and silver salts of mercaptides.
Among the organic silver salts described above, a silver salt of a fatty acid is preferably used, and silver behenate is more preferably used.
Silver arachidate and silver stearate.

For example, an organic acid alkali metal salt soap (eg, sodium behenate, sodium arachidate, etc.) is prepared by adding an alkali metal hydroxide (eg, sodium hydroxide, potassium hydroxide, etc.) to an organic acid. By using a control double jet method, silver nitrate and silver halide can be simultaneously added and mixed to prepare an aqueous organic silver salt dispersion used in the present invention.

The photothermographic material contains a reducing agent. Examples of reducing agents are described in U.S. Pat. No. 3,770,448;
No. 3,773,512, No. 3,593,863, and Research Disclosure No. 1702
9 and 29996, and include the following. Aminohydroxycycloalkenonone compounds (eg, 2-hydroxypiperidino-2-cyclohexenone); aminoreductones esters (eg, piperidinohexose reductone monoacetate) as precursors of reducing agents; N- Hydroxyurea derivatives (for example, Np-methylphenyl-N
Hydrazones of aldehydes or ketones (e.g. anthracene aldehyde phenylhydrazone); phosphoramidophenols; phosphoramidoanilines; polyhydroxybenzenes (e.g. hydroquinone, t-butyl-hydroquinone, isopropylhydroquinone and (2,5-dihydroxy-phenyl) methylsulfone); sulfhydroxamic acids (for example, benzenesulfhydroxamic acid); sulfonamidoanilines (for example, 4- (N-methanesulfonamido) aniline); 2-tetrazoli Ruthiohydroquinones (eg, 2-methyl-5- (1-phenyl-5-tetrazolylthio) hydroquinone); tetrahydroquinoxalines (eg, 1,2,3,4-tetrahydroquinoxaline); Synths; Azines (for example, a combination of an aliphatic carboxylic acid arylhydrazide and ascorbic acid); a combination of polyhydroxybenzene and hydroxylamine; reductone and / or hydrazine; hydroxamic acids; a combination of azines and sulfonamidophenols Α-cyanophenylacetic acid derivatives; combinations of bis-β-naphthol and 1,3-dihydroxybenzene derivatives; 5-pyrazolones; sulfonamide phenol reducing agents; 2-phenylindane-1,
3-dione and the like; chroman; 1,4-dihydropyridines (eg, 2,6-dimethoxy-3,5-dicarbethoxy-1,4-dihydropyridine); bisphenols (eg, bis (2-hydroxy-3- t-butyl-5
-Methylphenyl) methane, bis (6-hydroxy-m
-Tri) mesitol, 2,2-bis (4-hydroxy-3-methylphenyl) propane,
4,5-ethylidene-bis (2-t-butyl-6-methyl) phenol), ultraviolet-sensitive ascorbic acid derivatives and 3-pyrazolidones.

In the photothermographic material, for example, surfactants, antioxidants, stabilizers, plasticizers, ultraviolet absorbers, coating aids, and the like are used in addition to those described above.

Binders suitable for the photothermographic material are transparent or translucent, generally colorless, and include natural polymer synthetic resins, polymers and copolymers, and other film-forming media such as gelatin, gum arabic, and poly (vinyl alcohol). ), Hydroxyethyl cellulose, cellulose acetate, cellulose acetate butyrate,
Poly (vinylpyrrolidone), casein, starch, poly (acrylic acid), poly (methyl methacrylic acid), poly (vinyl chloride), poly (methacrylic acid), copoly (styrene-maleic anhydride), copoly (styrene-acrylonitrile) , Copoly (styrene-butadiene), poly (vinyl acetal) s (eg, poly (vinyl formal) and poly (vinyl butyral)), poly (esters), poly (urethane) s, phenoxy resins, poly (vinylidene chloride) , Poly (epoxides), poly (carbonates), poly (vinyl acetate), cellulose esters, and poly (amides). It may be hydrophilic or non-hydrophilic. In order to protect the surface of the light-sensitive material and prevent abrasion, a non-light-sensitive layer may be provided outside the light-sensitive layer. The binder used for these non-photosensitive layers may be the same or different from the binder used for the photosensitive layers.

The support is made of a plastic film (eg, polyethylene terephthalate, polycarbonate, polyimide, nylon, cellulose triacetate, polyethylene naphthalate, etc.) in order to prevent deformation of the image after development processing.

The heat-developable photosensitive material forms a photographic image by a heat-development process. The heat-developable light-sensitive material is used for reducing a silver source (organic silver salt), a photosensitive silver halide, a reducing agent and, if necessary, a silver tone. This is a photothermographic material which usually contains a color tone suppressing agent dispersed in a (organic) binder matrix.

The present invention uses such a photothermographic material,
Silver that could be easily recovered by separating into a support and a coating film using a specific solvent, a mixed solvent thereof, or a mixed solvent thereof and water, and treating the separated solvent layer. It is.

In addition, various waste liquids such as process waste liquids generated during the production of photothermographic materials, for example, residual coating liquid waste, stagnant loss waste liquid, abnormal loss waste liquid, and test waste liquid, are produced by the present invention. Silver recovery from the solution is also a target, and in the present invention, in particular, in the present invention, the support and the coating film are separated by using a specific solvent for the photothermographic material, and the separated coating solution is mixed with a waste solution. It is a preferable method to recover silver using a mixed solution. It is efficient and most preferable to use a method of recovering the solvent from the mixed solution in advance and then burning the residue, and then recovering silver from the residual ash.

[0036]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples.

(Preparation of Support) A 175 μm-thick PET film colored at a density of 0.170 (densitometer PDA-65 manufactured by Konica Corporation) was colored 8 w / m on both sides.
^{A 2} -minute corona discharge treatment was performed.

(Preparation of photosensitive silver halide emulsion) Water 90
Ossein gelatin having an average molecular weight of 100,000 in 0 ml 7.5
g and 10 mg of potassium bromide are dissolved at a temperature of 35 ° C. and p
After adjusting H to 3.0, an aqueous solution 3 containing 74 g of silver nitrate was used.
An aqueous solution containing potassium bromide and potassium iodide in a molar ratio of 70 ml and (98/2) and 1 × 10 ⁻⁴ mol of iridium chloride per mol of silver were controlled by a controlled double jet method while maintaining a pAg of 7.7. It was added over a minute. Thereafter, 4-hydroxy-6-methyl-1,3,3
a) Cubic silver iodobromide having an average grain size of 0.06 μm, a grain size variation coefficient of 12%, and a [100] face ratio of 87% by adjusting the pH to 5 with NaOH and adding 0.3 g of 7-tetrazaindene. Particles were obtained. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant, and after desalting, 0.1 g of phenoxyethanol was added to adjust the pH to 5.9 and the pAg to 7.5 to obtain a photosensitive silver halide emulsion.

(Preparation of Organic Silver Salt Compound) In 9450 ml of pure water, 233 g of behenic acid, 157 g of arachidic acid and 110 g of stearic acid were dissolved at 80 ° C. Next, while stirring at a high speed, 1000 m of a 1.5 M aqueous sodium hydroxide solution
1 was added. Next, after adding 13.8 ml of 60% concentrated nitric acid, the mixture was cooled to 55 ° C. and stirred for 30 minutes, and the silver halide emulsion (containing 0.08 mol of silver and 900 ml of water) was added in 5 seconds. After stirring for 5 minutes, 1410 ml of a 1 M silver nitrate solution was added over 2 minutes, the mixture was further stirred for 20 minutes, and water-soluble salts were removed by filtration. Thereafter, washing with deionized water and filtration are repeated until the conductivity of the filtrate becomes 2 μS / cm, and centrifugal dehydration is performed.
Drying with warm air was carried out until no weight loss was obtained, to obtain a powdered organic silver salt compound.

(Preparation of photosensitive emulsion dispersion) Polyvinyl butyral powder (Butvar B manufactured by Monsanto)
-79) 14.6 g was dissolved in 1457 g of methyl ethyl ketone, and 500 g of a powdery organic silver salt compound was gradually added while stirring with a dissolver-type homogenizer, followed by thorough mixing. Then add 1mm Zr beads (Toray) to 80
The dispersion was carried out at a peripheral speed of 13 m and a residence time in the mill of 0.5 minute with a media-type disperser (manufactured by gettzmann) filled with% to prepare a photosensitive emulsion dispersion.

(Preparation of Coating Solution for Photosensitive Layer) Each of the following addition solutions was added in the order described to prepare a coating solution for the photosensitive layer.

The photosensitive emulsion dispersion: 50 g Antifoggant 1 (10% methanol solution): 0.4 ml Calcium bromide (10% methanol solution): 0.9 ml Polyvinyl butyral (Monsanto Butv)
ar B-79): 13.3 g phthalazine: 0.3 g tetrachlorophthalic acid: 0.1 g 4-methylphthalic acid: 0.14 g infrared dye 1: 37 mg antifoggant 2 (6% MEK solution): 5.0 ml Developer (1,1-bis (2-hydroxy-3,5-dimethylphenyl) -2-methylpropane) (20% MEK
Solution): 12.5 ml Desmodur N3300 (Mobay Co., aliphatic isocyanate) 10% MEK solution: 1.60 ml The following layers were sequentially formed on a support to prepare a photothermographic material. The drying was performed at 75 ° C. for 5 minutes.

[0043]

Embedded image

<Coating on Back Side> Cellulose acetate butyrate (10% methyl ethyl ketone solution) 15 ml / m ² Matting agent (monodispersity 15%, average particle size 10 μm monodisperse silica) 30 mg / m ² <Photosensitive layer side coating> Photosensitive layer: The above-mentioned photosensitive layer coating solution was applied so that the coated silver amount was 2 g / m ² .

Surface protective layer: A solution having the following composition was applied on the photosensitive layer.

Methyl ethyl ketone 17 ml / m ² Cellulose acetate 2.3 g / m ² Matting agent (monodispersity 10% average particle size 4 μm monodisperse silica) 1 m ^{2 of the} photothermographic material obtained in a manner of 70 mg / m ² or more Using
The sheet was cut into 5 cm squares (400 sheets), stirred for 3 hours using 50 liters of various solvents shown in Table 1 (temperature: normal temperature), and the state of peeling of the coating film from the support was observed. Table 1 shows the results.

After separating the coating solution layer, the solvent was removed by distillation, the residue was incinerated, and the residual ash was separated from silver by the bluing method shown below. The silver recovery was evaluated on the following five scales. The results are shown in Table 1.

(Bluing method) A strong bluing solution (concentration: 0.1 to
(0.5% potassium cyanide) was gradually added thereto, and air was blown in while stirring, followed by stirring for 5 hours.

The solution is filtered, the enzyme is removed by a claw vacuum method, and a precipitant (zinc powder) is added to precipitate silver. The obtained crude silver was dried and the silver recovery was calculated.

The calculation of the silver recovery rate is based on 1 m ^{2 of the} photothermographic material.
Is incinerated without separating the support and the coating film as it is, and based on the amount of silver recovered from the residual ash, 5 is the recovery rate above the standard, 4 is equivalent to the standard, and 3 is the standard Slightly lower, 2 is considerably lower than the standard, and 1 is hardly recovered in 5 steps.

[0051]

[Table 1]

It can be seen that the use of the solvent of the present invention provides good separation between the support and the coating film and, as a result, a high silver recovery rate. The support separated using the solvent of the present invention had good coating film separation, and was at a level that could be used as it was in the support recovery step.

Example 2 Next, 10 liters of the photosensitive layer coating solution prepared in the step of preparing the photothermographic material of Example 1 was used as a waste solution due to process loss, and the coating solution obtained in Example 1 ( After the solvent was recovered in the same manner as in Example 1, the residue was incinerated and silver was recovered from the residual ash. The same silver recovery as in Example 1 could be obtained.

[0054]

According to the present invention, the support and the photosensitive coating can be easily separated from the photothermographic material, and the silver and the support can be recovered and reused.

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Claims (12)

[Claims] 1. A photothermographic material having a photosensitive layer and a protective layer on at least one of a support, wherein at least one of an organic solvent selected from hydrocarbon, alcohol, ketone and ester is used. A method for recovering silver from a photothermographic material, comprising using either a mixed solvent selected from alcohols or a mixed solvent of the organic solvent and water. 2. The hydrocarbon solvent is octane, o-xylene, m-xylene, p-xylene, cyclohexane,
Cyclopentane, dipentene, methylcyclohexane,
The method for recovering silver according to claim 1, wherein the method is any one of methylcyclopentane. 3. The alcohol solvent is methyl alcohol,
The silver recovery method according to claim 1, wherein the silver recovery method is any one of ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, sec-butyl alcohol, ter-butyl alcohol, and allyl alcohol. 4. An ester solvent comprising methyl formate, ethyl formate, propyl formate, butyl formate, isobutyl formate, isoamyl formate, methyl acetate, ethyl acetate, propyl acetate,
2. The silver recovery method according to claim 1, wherein the silver recovery method is any one of isopropyl acetate, butyl acetate, s-butyl acetate, isobutyl acetate, isoamyl acetate, and allyl acetate. 5. The ketone solvent is acetone, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone,
Methyl isobutyl ketone, methyl amyl ketone, diethyl ketone, dipropyl ketone, diisopropyl ketone,
2. The method for recovering silver according to claim 1, wherein the method is any one of diisobutyl ketone. 6. The method for recovering silver from a photothermographic material according to claim 1, wherein the mixed solvent is a mixed solvent of ethanol and toluene, isopropyl alcohol and xylene, butyl alcohol and solvent naphtha. 7. The method for recovering silver from a photothermographic material according to claim 1, wherein the weight ratio of water of the mixed solvent of the organic solvent and water is 80% or less. 8. A support and a coating film are separated from the photothermographic material using the solvent according to any one of claims 1 to 7, and the solvent is recovered from the separated coating film solution. A silver recovery method comprising recovering silver. 9. A film obtained by separating a support and a coating film from a photothermographic material using the solvent according to claim 1 and incinerating the separated coating solution. A silver recovery method comprising recovering silver from ash. 10. A support and a coating film are separated from a photothermographic material using the solvent according to claim 1;
A silver recovery method comprising recovering a solvent from a separated coating solution and then recovering silver from residual ash obtained by incinerating the residue. 11. A support and a coating film are separated from the photothermographic material using the solvent according to claim 1;
The method for recovering silver according to any one of claims 8 to 10, wherein a mixed solution obtained by adding a waste solution generated from a step of manufacturing a photothermographic material to the separated coating solution is used. 12. The silver recovery method according to claim 1, wherein the silver recovery method is a bluing method.