Separation and recovery method of aluminum foil laminate

Abstract

To provide a method capable of separating and recovering an aluminum foil from an aluminum foil laminate.SOLUTION: Provided according to the present invention is a separation and recovery method of an aluminum foil laminate including sequentially: a first releasing step of separating and recovering a hardly-releasable aluminum foil laminate; a dilution step; and a second releasing step of separating and recovering an easily-releasable aluminum foil laminate. Therein: releasing solution contains formic acid, carboxylate ester, and water; a sum of content of the formic acid and the carboxylate ester is equal to or greater than 30 wt% and equal to or less than 99 wt%; and a sum of content of the formic acid, the carboxylate ester, and the water is equal to or less than 100 wt%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for separating and recovering an aluminum foil laminate, in which a resin is laminated on at least one side of an aluminum foil, for separating the aluminum foil and the resin. [Background technology]

[0002] Traditionally, aluminum foil with resin laminated on both sides has been widely used as a packaging material for food and pharmaceuticals, where barrier properties are required to protect the contents from external environments such as oxygen, water vapor, and ultraviolet rays. In recent years, there has been a demand for recyclability in resin products, and packaging materials made solely from resin are being recycled actively.

[0003] For example, Patent Document 1 discloses a recycling method including a step of selectively dissolving and separating aluminum foil, a step of crushing the separated multilayer film layers and separating them based on differences in specific gravity, a step of heating the crushed material in an organic solvent to separate some of the resin components, and a step of recovering each component.

[0004] Furthermore, Patent Document 2 discloses a method for separating and recovering composite materials, which includes a crushing step for crushing the composite material, a peeling step for penetrating a peeling solution into the crushed material to dissolve the adhesive layer and thereby peel off the individual materials that make up the composite material, and a separation and recovery step for separating and recovering the individual materials by gravity sorting. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-205160 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-19003 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the above-mentioned conventional techniques have the following problems.

[0007] In the recycling method disclosed in Patent Document 1, the aluminum layer is completely dissolved, so it is not possible to recover it as metallic aluminum foil. Furthermore, the use of a strong basic aqueous solution may damage the resin that constitutes the film. Furthermore, the use of a strong basic aqueous solution places a heavy burden on the environment, making it incompatible with the recent increase in environmental awareness.

[0008] The separation and recovery method disclosed in Patent Document 2 peels off the adhesive layer by swelling it with a peeling solution, but the peeling process is long, lasting 4 to 30 hours, and there is also the problem that it cannot be applied to composite materials that are laminated by a method that does not involve an adhesive layer, such as heat lamination.

[0009] Furthermore, to peel hard-to-peel aluminum foil laminates such as battery casings, laminate tubes, and PTP (press-through package) laminates, a stripping solution containing a relatively high concentration of strong acid or strong base is required, while on the other hand, to peel easily peelable aluminum foil laminates such as PTP aluminum foil, cheese packaging, and chocolate packaging, a stripping solution with a low concentration may be sufficient. Therefore, using a relatively high concentration stripping solution even for easily peelable aluminum foil laminates is not preferable from the viewpoint of environmental impact.

[0010] Therefore, the present invention has been made in consideration of the above circumstances, and provides a method for separating and recovering an aluminum foil laminate including a resin layer and an aluminum foil layer in a manner that imposes a low environmental load. [Means for solving the problem]

[0011] In order to solve the above problem, the present inventors have conducted extensive research into methods for separating the resin layer and the aluminum foil of an aluminum foil laminate (hereinafter also simply referred to as "laminate"). The present inventors have found that a method for separating and recovering an aluminum foil laminate comprising, in order, a first peeling step in which a difficult-to-peel aluminum foil laminate is immersed in a stripping solution containing formic acid, a carboxylic acid ester, and water as main components in specific proportions, and the components are mixed together to peel the aluminum foil and the resin layer; a dilution step in which at least a portion of the stripping solution is diluted with water by 5 to 20 times to obtain a diluted stripping solution; and a second peeling step in which the easily-peelable aluminum foil laminate is peeled into the aluminum foil and the resin layer using the diluted stripping solution, enables separation and recovery without dissolving the aluminum foil, and furthermore, by using a weak acid with a low environmental impact and reusing the diluted acid, the aluminum foil laminate can be separated and recovered into the aluminum foil and the resin layer in a method with a lower environmental impact, which has led to the completion of the present invention.

[0012] That is, according to the present invention, an aluminum foil laminate in which an aluminum foil and a resin layer are laminated is provided with the following steps in this order: (1) a first peeling step in which a hard-to-peel aluminum foil laminate having a resin layer thickness of more than 7 μm is peeled into a first aluminum foil and a first resin layer using a peeling solution; a dilution step in which at least a part of the peeling solution is diluted with water by 5 to 20 times to obtain a diluted peeling solution; and (2) a second peeling step in which an easy-to-peel aluminum foil laminate having a resin layer thickness of 7 μm or less is brought into contact with the diluted peeling solution to peel into a second aluminum foil and a second resin layer, wherein the peeling solution contains formic acid at a concentration of 15 wt % to 98 wt %. The present invention provides a method for separating and recovering an aluminum foil laminate, characterized in that the aluminum foil laminate contains one or more carboxylic acid esters selected from the group consisting of methyl formate, ethyl formate, propyl formate, butyl formate, pentyl formate, hexyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, pentyl acetate, and hexyl acetate in an amount of 1 wt% to 84 wt%; and contains 1 wt% to 70 wt% of water, wherein the sum of the contents of the formic acid and the carboxylic acid esters is 30 wt% to 99 wt% and the sum of the contents of the formic acid, the carboxylic acid esters, and the water is 100 wt% or less.

[0013] In the method for separating and recovering an aluminum foil laminate of the present invention, by using the above-described stripping solution, the aluminum foil is hardly dissolved, and the aluminum foil and the resin are easily peeled off. In addition, by using a diluted stripping solution obtained by diluting the stripping solution used in the first peeling step for peeling the hard-to-peel aluminum foil laminate in the second peeling step for peeling the easy-to-peel aluminum foil laminate, a separation and recovery method with a lower environmental impact can be achieved.

[0014] The method may further include a step of crushing the hard-to-peel aluminum foil laminate before the first peeling step and / or crushing the easy-to-peel aluminum foil laminate before the second peeling step. By including the crushing step, the stripping solution and the diluted stripping solution can easily penetrate into the cross section of the aluminum foil laminate, making it easier to peel the aluminum foil laminate into the aluminum foil and the resin layer.

[0015] The method for separating and recovering an aluminum foil laminate of the present invention may further include a recovery step of recovering the diluted stripping solution after the dilution step. By recovering the diluted stripping solution from the reaction tank in which the first peeling step was performed and transferring it to another reaction tank in which the second peeling step is performed, the first aluminum foil and the first resin layer from which the hard-to-peel aluminum foil laminate was peeled and the second aluminum foil and the second resin layer from which the easy-to-peel aluminum foil laminate was peeled do not mix, and therefore efficient separation and recovery can be achieved.

[0016] The method for separating and recovering an aluminum foil laminate of the present invention may include, after the recovery step, a first washing step of washing the aluminum foil and the resin layer with a washing solution, and a first dehydration step of removing the washing solution adhering to the first aluminum foil and the first resin layer, in that order. By including these steps, the amount of diluted stripping solution remaining on the first aluminum foil and the first resin layer after peeling the hard-to-peel aluminum foil laminate is reduced, thereby suppressing odor and corrosion of the aluminum foil.

[0017] The method for separating and recovering an aluminum foil laminate of the present invention may include, after the second peeling step, a draining step of discharging a diluted stripping solution, a second washing step of washing the second aluminum foil and the second resin layer with a washing solution, and a second dehydration step of removing the washing solution adhering to the aluminum foil and the resin layer, in that order. By including these steps, the amount of diluted stripping solution remaining on the second aluminum foil and the second resin layer after peeling the easily peelable aluminum foil laminate is reduced, and odor is suppressed.

[0018] The method may further include a first preliminary dehydration step between the first stripping step and the dilution step, in which a predetermined amount of the stripping solution is removed, and / or a second preliminary dehydration step between the second stripping step and the second cleaning step, in which a predetermined amount of diluted stripping solution is removed. By including the first preliminary dehydration step, the amount of stripping solution can be reduced in advance according to the desired concentration and amount of diluted stripping solution, thereby reducing the amount of water used for dilution.

[0019] The method may further include a first separation step between the first washing step and the first dehydration step, in which the first aluminum foil and the first resin layer are separated by gravity separation, and / or a second separation step between the second washing step and the second dehydration step, in which the second aluminum foil and the second resin layer are separated by gravity separation. By including the first separation step and / or the second separation step, it becomes possible to recover the peeled aluminum foil and resin layer, respectively. [Effects of the Invention]

[0020] The method for separating and recovering an aluminum foil laminate of the present invention uses a weak acid as a stripping solution, so that the aluminum foil laminate can be separated into the aluminum foil and the resin layer without dissolving the aluminum foil, and further has a lower environmental impact than conventional separation and recovery methods that use strong acids or alkalis. In addition, since the stripping solution is recovered and reused, the aluminum foil laminate can be separated and recovered in a method with a lower environmental impact. [Brief explanation of the drawings]

[0021] [Figure 1]3 is a flowchart showing a method for separating and recovering an aluminum foil laminate according to the first embodiment. [Figure 2] 10 is a flowchart showing a method for separating and recovering an aluminum foil laminate according to a second embodiment. [Figure 3] 10 is a flowchart showing a method for separating and recovering an aluminum foil laminate according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] (First embodiment) As shown in Figure 1, the separation and recovery method for aluminum foil laminates of the present invention targets difficult-to-peel aluminum foil laminates and easily peelable aluminum foil laminates containing aluminum foil and resin. The difficult-to-peel aluminum foil laminate is contacted with an aluminum foil laminate peeling solution containing formic acid, a carboxylic acid ester, and water as main components, with each component blended in a specific ratio, to peel off the first aluminum foil and the first resin layer. A first peeling step S10, and a dilution step S20 in which at least a portion of the peeling solution is diluted with water by 5 to 20 times to obtain a diluted peeling solution, are sequentially provided. Further, a second peeling step S30 is provided in which the easily peelable aluminum foil laminate is contacted with the diluted solution to peel off the second aluminum foil and the second resin layer. This allows the aluminum foil and resin to be separated and recovered using a method with low environmental impact. (aluminum foil laminate)

[0023] In the present invention, the aluminum foil laminate includes at least aluminum foil and a resin. Preferably, it is a laminate in which a resin film is laminated on each side of the aluminum foil. An adhesive, paper, nonwoven fabric, anchor coat, etc. may be provided between the aluminum foil and the resin film.

[0024] The laminate is generally in the form of a sheet, and can be formed by laminating one or more resin films and aluminum foils together.

[0025] The method for bonding the layers constituting the laminate is not particularly limited, and specific examples include dry lamination using a two-component curing adhesive such as a polyester urethane or polyester adhesive, co-extrusion, extrusion coating, extrusion lamination, heat sealing, and heat lamination using an anchor coating agent. (resin)

[0026] The resin constituting the aluminum foil laminate is preferably a resin film. As the resin, a wide variety of films made of known resins can be used, and there is no particular limitation. Specifically, a film made of one or more resins selected from polyethylene, polypropylene, polybutylene, polyethylene terephthalate, polyethylene naphthalate, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene vinyl acetate copolymer, polyamide, polyimide and vinyl chloride can be used. (aluminum foil)

[0027] The aluminum foil constituting the aluminum foil laminate is not particularly limited, and known materials can be used. For example, any material for aluminum foil used in packaging materials, such as A1N30 material, A8021 material, and A8079 material specified in JIS H4160:1994, can be used. (Hard-to-peel aluminum foil laminate)

[0028] A difficult-to-peel aluminum foil laminate refers to an aluminum foil laminate in which the resin layer is thicker than 7 μm. When resin layers are formed on both sides of the aluminum foil, this refers to a laminate in which at least one resin layer is thicker than 7 μm. Such a laminate can be manufactured by, for example, extrusion lamination. Resins with metal adhesive properties, such as modified polyolefins and ionomers, can be used as the resin layer. Such aluminum foil laminates have relatively high mechanical and chemical adhesion between the aluminum foil and the resin layer, requiring a relatively concentrated stripping solution for peeling. When the difficult-to-peel aluminum foil laminate has multiple resin layers, it is sufficient that at least one resin layer has the above-described configuration. The thickness of the other resin layers, the type of resin, and the lamination method are not particularly limited.

[0029] Although not particularly limited, any known method for improving the adhesion between the aluminum foil and the resin layer can be employed. For example, the aluminum foil may be subjected to a surface treatment such as a chemical conversion treatment, a corona treatment, or a roughening treatment.

[0030] Such hard-to-peel aluminum foil laminates are used in applications requiring strength, chemical resistance, etc., and are employed in applications such as battery exterior packaging materials, laminate tubes, and PTP laminates. (Easily peelable aluminum foil laminate)

[0031] An easily peelable aluminum foil laminate refers to an aluminum foil laminate in which the mechanical and chemical adhesion between the aluminum foil and the resin layer is relatively low. Specifically, it refers to a laminate in which the resin layer has a thickness of 7 μm or less. When a resin layer is formed on both sides of the aluminum foil, it refers to a laminate in which the thickness of all resin layers is 7 μm or less.

[0032] Such laminates can be produced by laminating, for example, by dry lamination using gravure coating. Resins such as polyolefins and polyamides can be used as the resin layer, but are not limited thereto. This also includes those simply coated or printed on the surface of aluminum foil.

[0033] Such easily peelable aluminum foil laminates are used in applications such as aluminum foil for PTP, packaging material for cheese, and packaging material for chocolate. (Aluminum foil laminate peeling solution)

[0034] The stripping solution for aluminum foil laminates of the present invention contains 15 wt% to 98 wt% formic acid, 1 wt% to 84 wt% of one or more carboxylic acid esters selected from the group consisting of methyl formate, ethyl formate, propyl formate, butyl formate, pentyl formate, hexyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, pentyl acetate, and hexyl acetate, and 1 wt% to 70 wt% of water, wherein the sum of the contents of the formic acid and the carboxylic acid esters is 30 wt% to 99 wt%, and the sum of the contents of the formic acid, the carboxylic acid esters, and the water is 100 wt% or less. The components of the stripping solution for aluminum foil laminates used in the present invention are described in detail below. (formic acid)

[0035] Formic acid is a type of carboxylic acid, which is an organic acid. Unlike strong acids such as hydrochloric acid and sulfuric acid, carboxylic acids react violently with aluminum foil and are not lost during separation from the resin layer. On the other hand, formic acid exhibits the strongest acidity among monovalent aliphatic carboxylic acids, with an acidity constant Ka of 1.8 x 10 -4 For example, the acidity constant Ka of acetic acid is 1.8 × 10 -5 Since the Ka of formic acid is 10 times larger, it breaks the adhesion at the aluminum interface and the resin layer interface, further promoting peeling between the aluminum foil and the resin layer.

[0036] However, unlike strong acids such as hydrochloric acid, formic acid does not ionize most monovalent aliphatic carboxylic acids. Therefore, to promote the peeling action of aluminum laminates using formic acid, based on Le Chatelier's principle, it is important to (a) increase the concentration of formic acid to shift the reaction equilibrium toward the side that promotes the peeling action, (b) increase the amount of carboxylic acid that ionizes in the reaction field, and (c) as a physical effect, to make it easier for formic acid to penetrate into the resin and reach the interface where the laminates are bonded.

[0037] The stripping solution of the present invention must contain 15 wt% to 98 wt% of formic acid, and the sum of the content of formic acid and the content of the carboxylic acid ester described below must be 30 wt% to 99 wt%. If the formic acid content is less than 15 wt%, the separation effect will not work sufficiently due to Le Chatelier's principle. On the other hand, if only formic acid is used, i.e., if the formic acid content is 100 wt% and no carboxylic acid ester is included, the physical penetration into the resin layer will be insufficient as described above, and the resin layer will not be sufficiently stripped.

[0038] Therefore, the content of formic acid in the stripping solution is not particularly limited as long as the sum of the contents of formic acid and carboxylic acid ester is 30 wt % or more and 99 wt % or less, but is preferably 15 wt % or more and 98 wt % or less, more preferably 20 wt % or more and 80 wt % or less, and even more preferably 45 wt % or more and 65 wt % or less.

[0039] The sum of the contents of formic acid and carboxylic acid ester in the stripping solution is preferably 30 wt% to 99 wt%, more preferably 40 wt% to 99 wt%, and even more preferably 65 wt% to 85 wt%. If the sum of the contents of formic acid and carboxylic acid ester exceeds 99 wt%, the remaining water will be less than 1 wt%, making it difficult to obtain the hydrolysis effect described below. On the other hand, if the sum of the contents of formic acid and carboxylic acid ester is less than 30 wt%, the laminate stripping effect of formic acid and carboxylic acid ester cannot be obtained.

[0040] The stripping solution used in the present invention may further contain a carboxylic acid other than formic acid, as long as it contains 15 wt% to 98 wt% of formic acid and the sum of the contents of formic acid and the carboxylic acid ester is 30 wt% to 99 wt%. For example, mixing acetic acid with formic acid further enhances the laminate stripping effect of formic acid. Examples of such carboxylic acids other than formic acid include acetic acid and propionic acid. As long as the stripping solution contains 15 wt% to 98 wt% of formic acid and the sum of the contents of formic acid and the carboxylic acid ester is 30 wt% to 99 wt%, the content of the carboxylic acid other than formic acid in the stripping solution is not particularly limited, but is preferably 69 wt% or less, and more preferably 22.5 wt% or less. (carboxylic acid ester)

[0041] In the present invention, the carboxylic acid ester is one or more selected from the group consisting of methyl formate, ethyl formate, propyl formate, butyl formate, pentyl formate, hexyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, pentyl acetate, and hexyl acetate. The carboxylic acid ester penetrates into a resin layer such as PVC or OPP, swelling the resin layer and facilitating peeling from the aluminum foil.

[0042] The stripping solution preferably contains 1 wt% to 84 wt% of carboxylic acid ester, and the sum of the content of carboxylic acid ester and formic acid is preferably 30 wt% to 99 wt%. Without a carboxylic acid ester, formic acid does not sufficiently penetrate the resin layer, making it impossible to sufficiently strip resin layers such as PVC and OPP. On the other hand, in a stripping solution of the present invention containing at least 15 wt% or more of formic acid, if the carboxylic acid ester content is greater than 84 wt%, the remaining water content excluding formic acid will be less than 1 wt% at most, making it difficult to achieve the effects of water (due to hydrolysis) described below.

[0043] Furthermore, the content of the carboxylic acid ester in the stripping solution is more preferably 5 wt% to 65 wt%, and even more preferably 20 wt% to 65 wt% in addition to the above range. This is because an aqueous solution containing a carboxylic acid such as formic acid or acetic acid can dissolve even esters that are normally immiscible in water, up to hexyl acetate with a carbon number of 7. However, if the carbon number exceeds 7, the ester becomes immiscible in water, the water and the carboxylic acid ester separate, and the solution no longer functions as a stripping solution for laminates. (water)

[0044] In the present invention, the stripping solution contains 1 wt% to 70 wt% water. However, the sum of the contents of formic acid, carboxylic acid ester, and water is 100 wt% or less. When water is present in the stripping solution, a small portion of the carboxylic acid ester is hydrolyzed in the acidic stripping solution by formic acid to form formic acid and acetic acid, enabling the stripping action of the laminate to be sustained for a long period of time. However, the hydrolysis of ordinary carboxylic acid esters requires an acid catalyst such as a strong acid such as sulfuric acid or hydrochloric acid, and therefore hydrolysis does not proceed sufficiently with water alone.

[0045] Therefore, in the stripping solution used in the present invention, although the equilibrium shifts toward the ionization of formic acid due to hydrolysis of the carboxylic acid ester in the presence of water, promoting the stripping action of the laminate, the carboxylic acid ester is hardly lost in the reaction. Therefore, in the present invention, a stripping solution containing an appropriate amount of formic acid, carboxylic acid ester, and water is preferred, and more specifically, the water content is more preferably 5 wt% to 50 wt%, and even more preferably 5 wt% to 35 wt%, in addition to the above range. (Remainder)

[0046] The stripping solution used in the present invention may contain, as the balance other than the above-mentioned components, one or more additives (solvents) selected from the group consisting of ketones, ethers, alkylbenzenes, dioxolanes, and cycloalkanes. In particular, since the stripping solution of the present invention contains water, the stripping solution may separate into two layers depending on the ratio of carboxylic acid ester to formic acid. Therefore, the above-mentioned solvents may be added appropriately to favorably mix the stripping solution. Furthermore, although ketones, ethers, aromatic hydrocarbons, and heterocyclic compounds do not have the same effect as carboxylic acid esters, they still have the ability to penetrate into the resin layer, so it is more preferable to add the above-mentioned solvents to the balance.

[0047] Examples of ketones that can be used in the present invention include acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, isophorone, acetophenone, and benzophenone. Of these, methyl ethyl ketone is often used as a true solvent for resin coating agents and is preferred from the viewpoint of solubility.

[0048] Examples of ethers include dimethyl ether, ethyl methyl ether, diethyl ether, diphenyl ether, ethylene oxide, tetrahydrofuran (THF), furan, 1,4-dioxane, anisole, benzofuran, dibenzofuran, and crown ether. Taking into consideration miscibility with water, tetrahydrofuran (THF), furan, and 1,4-dioxane are preferred.

[0049] As the alkylbenzene, xylene or toluene can be added as appropriate. Dioxolane is preferred because it has good miscibility with water and penetrates well into the resin layer. As the cycloalkane, cyclohexane, cycloheptane, cyclooctane, etc. can be used.

[0050] When the stripping solution used in the present invention contains an additive such as a ketone, ether, alkylbenzene, dioxolane, or cycloalkane, the content of the additive is preferably 10 wt% or more and 69 wt% or less, and more preferably 16.7 wt% or more and 50 wt% or less. (Other additives)

[0051] The stripping solution used in the present invention may contain additives such as buffer solutions as long as they do not impair the ability to strip laminates. For example, buffer solutions composed of phosphoric acid and alkali metal hydroxides have the effect of stabilizing the pH of the stripping solution, but adding excessive additives may slow down the reaction that promotes the stripping of laminates. Therefore, in the present invention, the amount of additive added is preferably 3 wt% or less. (Diluted stripping solution)

[0052] The diluted stripper solution of the present invention can be obtained by diluting the stripper solution with water in a ratio of 5 to 20 times in the dilution step.

[0053] The diluted stripping solution of the present invention contains 1.5 wt% to 9.8 wt% formic acid, 0.1 wt% to 8.4 wt% of one or more carboxylic acid esters selected from the group consisting of methyl formate, ethyl formate, propyl formate, butyl formate, pentyl formate, hexyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, pentyl acetate, and hexyl acetate, and 10 wt% to 97 wt% water, and the sum of the contents of the formic acid and the carboxylic acid esters may be 3 wt% to 9.9 wt% and the sum of the contents of the formic acid, the carboxylic acid ester, and the water may be 100 wt% or less. Within this concentration range, odor is suppressed and damage to the aluminum foil and resin layer is suppressed, allowing for efficient peeling of the easily peelable aluminum foil laminate. (First peeling step S10)

[0054] In the present invention, the first peeling step S10 is a step of peeling the first aluminum foil and the first resin layer constituting the difficult-to-peel aluminum foil laminate by contacting the difficult-to-peel aluminum foil laminate with a peeling solution. According to one embodiment of the separation and recovery method of the present invention, the first peeling step S10 may be a step of immersing the difficult-to-peel aluminum foil laminate in the peeling solution and stirring it under specific conditions to peel it off.

[0055] In the separation and recovery method of the present invention, the first peeling step S10 is performed under the temperature conditions of 20° C. to 90° C. and the stirring time is 1 minute to 24 hours. If the first peeling step S10 is performed under these conditions in the peeling solution of the present invention, each layer can be peeled off in a relatively short time without altering the aluminum foil surface of the hard-to-peel aluminum foil laminate.

[0056] If the temperature is lower than 20°C, it takes time for the stripping solution to penetrate into the resin layer, which can result in a longer stripping time. If the temperature is higher than 90°C, some of the components of the stripping solution will volatilize, changing the compounding ratio and potentially resulting in a longer stripping time. From these perspectives, a more preferable temperature condition is 40°C or higher and 80°C or lower.

[0057] The stirring time is more preferably 10 minutes or more and 10 hours or less in order to fully peel the hard-to-peel aluminum foil laminate and to prevent deterioration of the aluminum foil surface.

[0058] The weight ratio of the weight of the stripping solution to the weight of the hard-to-peel aluminum foil laminate immersed in the stripping solution is preferably 10:1 to 10:5, more preferably 10:2 to 10:4. When the weight ratio of the laminate to the stripping solution is high, the penetration of the stripping solution into the resin can be expected to be promoted by collisions between the individual pieces of the laminate. Furthermore, the amount of laminate that can be processed at one time can be increased. When the weight ratio of the laminate immersed in the stripping solution exceeds 10:5, stirring becomes difficult and the stirring device may stop due to overload. (Dilution step S20)

[0059] The separation and recovery method of the present invention includes a dilution step S20 following the first peeling step S10. The dilution step refers to a step in which at least a portion of the stripping solution in the first peeling step S10 is diluted with water by a ratio of 5 to 20 times to obtain a diluted stripping solution. Dilution with water less than 5 times results in a large amount of stripping solution remaining on the first aluminum foil and first resin layer after the hard-to-peel aluminum foil laminate has been peeled off, which is undesirable because it hinders recycling and causes odors. Dilution with water more than 20 times may result in the diluted stripping solution being too diluted, which may result in an insufficient concentration for peeling the easy-to-peel aluminum foil laminate when reused in the second peeling step S30. In addition, a large amount of water is required for dilution, which is undesirable from a cost perspective because a large tank is required.

[0060] The dilution method is not particularly limited, and may be a method of immersing the hard-to-peel aluminum foil laminate in water or a method of showering the hard-to-peel aluminum foil laminate with water. (Second peeling step S30)

[0061] In the present invention, the second peeling step S30 is a step of bringing the easily peelable aluminum foil laminate into contact with a diluted peeling solution to peel off the second aluminum foil and the second resin layer that constitute the easily peelable aluminum foil laminate. In the method for separating and recovering an aluminum foil laminate according to the first embodiment, the easily peelable aluminum foil laminate is put into and brought into contact with the diluted stripping solution in the second peeling step S30.

[0062] In the separation and recovery method of the present invention, the second peeling step S30 is preferably performed by immersing the easily peelable aluminum foil laminate in a diluted solution and stirring the same, and the temperature conditions are preferably 20 ° C. or higher and 90 ° C. or lower, and the stirring time is preferably 1 minute or higher and 24 hours or lower. If the second peeling step is performed under such conditions in the diluted peeling solution of the present invention, each layer can be peeled off in a relatively short time without altering the aluminum foil surface of the easily peelable aluminum foil laminate.

[0063] If the temperature is lower than 20°C, it takes time for the diluted stripping solution to penetrate into the resin layer, which can result in a longer stripping time. If the temperature is higher than 90°C, some of the components of the diluted stripping solution will volatilize, changing the compounding ratio and potentially resulting in a longer stripping time. From these viewpoints, a more preferable temperature condition is 40°C or higher and 80°C or lower.

[0064] The stirring time is more preferably 10 minutes or more and 10 hours or less in order to fully peel the easily peelable aluminum foil laminate and to prevent deterioration of the aluminum foil surface.

[0065] The weight ratio of the diluted stripping solution to the weight of the easily peelable aluminum foil laminate immersed in the diluted stripping solution is preferably 10:1 to 10:5, more preferably 10:2 to 10:4. When the weight ratio of the laminate to the easily peelable solution is high, the collision of the individual pieces of the laminate can be expected to promote penetration of the diluted stripping solution into the resin. Furthermore, the amount of laminate that can be processed at one time can be increased. When the weight ratio of the laminate immersed in the diluted stripping solution exceeds 10:5, stirring becomes difficult and the stirring device may stop due to overload. (Second embodiment)

[0066] FIG. 2 is a flowchart showing the method for separating and recovering an aluminum foil laminate according to the second embodiment.

[0067] The separation and recovery method of the second embodiment differs in that it includes a recovery step S24 and a first spin-drying step S28 following the dilution step S20, and further includes a draining step S34 and a first spin-drying step S38 following the second peeling step S30. Since the method is otherwise similar to the first embodiment, the following description will focus on the differences and omit any further description. (Recovery process S24)

[0068] The separation and recovery method of the second embodiment may include a recovery step S24 of recovering the diluted stripping solution after the dilution step. In this step, the diluted stripping solution is recovered from the reaction tank in which the first peeling step S10 was performed and transferred to another reaction tank for the second peeling step S30. This prevents the first aluminum foil and first resin layer from being peeled off from the hard-to-peel aluminum foil laminate from being mixed with the second aluminum foil and second resin layer from being peeled off from the easy-to-peel aluminum foil laminate, allowing for efficient separation and recovery. (First dehydration step S28)

[0069] The first dehydration step S28 is a step of removing the diluted stripping solution and cleaning solution adhering to the first aluminum foil and the first resin layer from the peeled hard-to-peel aluminum foil laminate. The dehydration method is not particularly limited, and may be, for example, centrifugal dehydration. (Drainage step S34)

[0070] The separation and recovery method of the second embodiment may include a draining step S34 of discharging the diluted stripping solution following the second peeling step. By including this step, the diluted stripping solution adhering to the aluminum foil and resin layer peeled from the easily peelable aluminum foil laminate can be removed, and odor can be suppressed.

[0071] The diluted stripping solution removed in the draining step S34 may or may not be reused in the second stripping step S30, but it is preferable not to reuse it because it contains a small amount of formic acid and carboxylic acid ester, which is insufficient for stripping the easily peelable aluminum foil laminate. (Second dehydration step S38)

[0072] The separation and recovery method of the second embodiment includes a second dehydration step S38 following the drainage step S34. The second dehydration step S38 is a step of removing the diluted stripping solution and cleaning solution adhering to the second aluminum foil and the second resin layer obtained by peeling the easily peelable aluminum foil laminate. The dehydration method is not particularly limited, and may be, for example, centrifugal dehydration. (Third embodiment)

[0073] FIG. 3 is a flowchart showing a method for separating and recovering an aluminum foil laminate according to the third embodiment.

[0074] The separation and recovery method of the third embodiment includes a crushing step S08 prior to the first peeling step S10 and the second peeling step S20, and includes the first peeling step S10, the first preliminary dehydration step S12, the dilution step S20, the recovery step S24, the first washing step S25, and the first separation step S26 in that order, and the second peeling step S30, the draining step S34, the second washing step S35, the second separation step S36, and the second dehydration step S39 in that order, and further includes a method of recovering the first aluminum foil and the first resin layer peeled from the hard-to-peel aluminum foil laminate, and the second aluminum foil and the second resin layer peeled from the easy-to-peel aluminum foil laminate, respectively.

[0075] In the following description, differences from the first and second embodiments will be described, and other descriptions will be omitted. (Crushing process S08)

[0076] The separation and recovery method of the present invention may include a step of crushing the hard-to-peel aluminum foil laminate before the first peeling step S10 and / or a step of crushing the easy-to-peel aluminum foil laminate before the second peeling step S30.

[0077] The crushing step is a step of crushing the hard-to-peel aluminum foil laminate and / or the easy-to-peel aluminum foil laminate into small pieces, and is carried out to improve the processing efficiency of the first peeling step S10 and / or the second peeling step S30.

[0078] The method for crushing the aluminum foil laminate is not particularly limited, but a known crusher generally used for crushing packaging, resin containers, etc. can be suitably used. Specific examples include a uniaxial crusher, a biaxial crusher, a pusher crusher, and a screw crusher that cut and crush the aluminum foil laminate with a blade. The blade rotation speed and crushing time of such a crusher can be appropriately set depending on the amount, thickness, and materials contained in the aluminum foil laminate.

[0079] In the crushing process of the present invention, the size of the small pieces after crushing is not limited, and generally includes crushing into a roughly geometric planar shape with a longitudinal length of about 20 mm to 300 mm, as well as crushing into a roughly geometric planar shape of about 2 mm to 20 mm and fine crushing into pieces of less than 2 mm. The size of the small pieces of the aluminum foil laminate in this crushing process is not particularly limited, but preferably has a roughly geometric planar shape with a longitudinal length of about 1 mm to 300 mm. More preferably, it has a roughly geometric planar shape with a longitudinal length of about 5 mm to 50 mm. By having the small pieces have a roughly geometric planar shape with a longitudinal length of about 5 mm to 50 mm, the corners of the ends of the small pieces are less likely to bend, making it easier to peel the aluminum foil and the resin layer from each other. Furthermore, small pieces within this size range are less likely to fly and can be obtained in a short time using a known crusher, so the separation of the aluminum foil and the resin layer is efficient. Note that the roughly geometric planar shape referred to here includes not only roughly triangular and roughly rectangular shapes, but also circles, stars, and irregular shapes that combine these. The term "approximate triangle" or "approximate rectangle" is not limited to triangles formed by three straight lines, such as equilateral triangles, isosceles triangles, and right-angled triangles, or rectangles formed by four straight lines, such as squares, rectangles, rhombus, and trapezoids, but also includes shapes with a bent or missing corner or a curved side. For pentagons, shapes with more than two corners, and irregular shapes, the longitudinal length may be defined as the diameter of a circumscribing circle.

[0080] In addition, cuts or small holes may be made in the aluminum foil laminate before, after, and / or during the crushing process. By making cuts or small holes in the aluminum foil laminate, the stripping solution or a diluted solution of the stripping solution comes into closer contact with the peripheral edges of the cuts or small holes in the aluminum foil laminate, promoting peeling. Methods for making cuts or small holes in the aluminum foil laminate include using a uniaxial crusher, a biaxial crusher, a pusher crusher, a screw crusher, or the like to make cuts in the aluminum foil laminate at a slower rotation speed than when crushing the aluminum foil laminate, or perforating the aluminum foil laminate with a needle to make small holes. (First peeling step S10 in the third embodiment)

[0081] In the separation and recovery method of the third embodiment, in the second peeling step S10, the crushed hard-to-peel aluminum foil laminate is immersed in the peeling solution and stirred, so that peeling can be performed in a shorter time. (First preliminary dehydration step S12)

[0082] The separation and recovery method of the present invention may include a first preliminary dehydration step S12 in which a predetermined amount of stripping solution is removed prior to the dilution step S20. By including the first preliminary dehydration step S12, the amount of water used for dilution can be reduced by reducing the amount of stripping solution in advance according to the concentration and amount of the desired diluted stripping solution. In addition, it is also preferable to reuse the stripping solution removed in this step in the first peeling step S10 of another hard-to-peel aluminum foil laminate, as this reduces the amount of new stripping solution used and makes it a separation and recovery method with a lower environmental impact.

[0083] When the first preliminary dehydration step S12 is performed, the amount of the diluted stripping solution is reduced, and therefore the first preliminary dehydration step S12 may be performed as appropriate depending on the amount of the hard-to-peel aluminum foil laminate to be separated and recovered. (First cleaning step S25)

[0084] The separation and recovery method of the present invention may include, after the recovery step S24, a first washing step S25 of washing the first aluminum foil and the first resin layer with a washing solution, and a first dehydration step S28 of removing the washing solution adhering to the first aluminum foil and the first resin layer, in that order. By including these steps, the amount of diluted stripping solution remaining on the first aluminum foil and the first resin layer after peeling the hard-to-peel aluminum foil laminate is reduced, thereby suppressing odor and corrosion of the aluminum foil.

[0085] The washing method is not particularly limited, and may be a method in which the aluminum foil and the resin layer from which the hard-to-peel aluminum foil laminate has been peeled are placed in a washing solution, or a method in which the washing solution is showered. The washing liquid is not particularly limited, and organic solvents such as water, ethanol, toluene, ketones, and esters can be used alone or in mixture. Additives such as surfactants and neutralizing agents may also be added as needed. Washing with water is preferred. Furthermore, when the first separation step S26 described below is performed, washing with a separation liquid may also be used. (First separation step S26)

[0086] The separation and recovery method of the present invention includes a first separation step S26 between the first washing step S25 and the first dehydration step S28, in which the first aluminum foil and the first resin layer are separated by gravity separation. The liquid that can be used for gravity separation may be water, an aqueous solution, or a heavy liquid, and is selected appropriately depending on the desired specific gravity. The gravity separation liquid may also be a washing liquid.

[0087] The specific gravity of resins is, for example, 0.91 to 0.965 for polyethylene, approximately 0.95 for ethylene-vinyl acetate copolymer resin, 1.01 to 1.04 for ABS resin, 1.04 to 1.07 for polystyrene, 1.17 to 1.20 for acrylic (PMMA), 1.01 to 1.02 for nylon, approximately 1.40 for polyethylene terephthalate, 1.23 to 1.45 for polyvinyl chloride, 1.37 to 1.65 for phenolic resin, approximately 1.76 for polyvinylidene fluoride, and approximately 1.8 for epoxy resin. In contrast, the specific gravity of aluminum is approximately 2.70, which is significantly different from the specific gravity of resin. Therefore, the difference in specific gravity between resin and aluminum foil can be utilized to easily separate (sort) them.

[0088] Specifically, even the highest specific gravity of resin is about 1.8, which is significantly different from the specific gravity of aluminum, 2.70. Therefore, by selecting and using a specific gravity separation liquid with a specific gravity of 2.6 or less depending on the type of resin to be separated, the aluminum foil will settle and the resin will float, allowing them to be separated. The type of specific gravity separation liquid is not limited and can be selected depending on the type of resin to be separated. Examples of the specific gravity separation liquid include medium-chain fatty acid triglycerides with a specific gravity of 0.91, water with a specific gravity of 1, ethylene glycol with a specific gravity of about 1.11, brine that can be adjusted to a specific gravity of 1.01 to 1.21 depending on the salt concentration, the stripping solution described above that can be adjusted to a specific gravity of 0.92 to 1.21 depending on the formic acid concentration, carbon tetrachloride with a specific gravity of about 1.58, pentachloroethane with a specific gravity of about 1.68, trichloroethylene with a specific gravity of about 1.46, a zinc chloride aqueous solution with a specific gravity of about 2.0, and a zinc bromide aqueous solution with a specific gravity of about 2.21. The resin may be dissolved in the gravity separation liquid, making it possible to separate it from the aluminum foil. However, in order to recover and recycle the resin, it is preferable to use a gravity separation liquid that does not easily dissolve the resin.

[0089] In addition, the first separation step S26 may separate not only aluminum foil and resin but also different types of resin. For example, when an aluminum foil laminate contains multiple resins with different specific gravities, such as polyethylene and polystyrene, the resins may be further separated by type after separating the aluminum foil from the aluminum foil laminate. For example, saltwater with a specific gravity of approximately 1.10 is first prepared as a specific gravity sorting liquid. Small pieces of an aluminum foil laminate containing polyethylene with a specific gravity of 0.91 to 0.965, polystyrene with a specific gravity of 1.04 to 1.07, and aluminum foil with a specific gravity of approximately 2.70 are separated in the saltwater. The resin components containing polyethylene and polystyrene float in the specific gravity sorting liquid, while the aluminum foil settles. The settled aluminum foil is then removed, and the specific gravity sorting liquid containing the remaining resin is filtered to extract the resin. This is then dropped into water with a specific gravity of 1.0 as the specific gravity sorting liquid. This causes the polyethylene to float in the specific gravity sorting liquid, while the polystyrene sinks. This allows the separation of different resins, polyethylene and polystyrene, as well.

[0090] Here, a method for separating the precipitated and floating components in the gravity separation liquid will be described in detail. The aluminum foil and resin can be separated by separating the layer containing the precipitated components of the gravity separation liquid or the layer containing the supernatant component of the gravity separation liquid. Specifically, the gravity separation liquid containing the aluminum foil and resin is placed in a tank to settle the aluminum foil and float the resin, and a plug at the bottom of the tank is opened to remove the precipitated components containing the aluminum foil from the tank. Once the precipitated components have been removed, the plug is closed to separate the gravity separation liquid containing the resin remaining in the tank from the gravity separation liquid containing the aluminum foil removed from the tank. Alternatively, the gravity separation liquid containing the aluminum foil and resin can be placed in a tank to settle the aluminum foil and float the resin, and the resin floating in the gravity separation liquid can be scooped up using a mesh, filter, or the like to separate the aluminum foil sunk in the gravity separation liquid from the scooped resin. (First dehydration step S28)

[0091] The first dehydration step S28 is a step of removing the diluted stripping solution and cleaning solution adhering to the first aluminum foil and the first resin layer obtained by peeling the hard-to-peel aluminum foil laminate, but when the first separation step S26 is included, it may be a step of recovering the settled first aluminum foil and removing the specific gravity separation solution adhering to the first aluminum foil. The dehydration method is not particularly limited, and may be, for example, dehydration by centrifugal dehydration. (Second cleaning step S35)

[0092] The separation and recovery method of the present invention may include a second washing step S35 following the second peeling step S30. The second washing step refers to a step of washing away the diluted stripping solution adhering to the second aluminum foil and the second resin layer obtained by peeling the easily peelable aluminum foil laminate in the second peeling step.

[0093] The washing method is not particularly limited, and may be a method in which the second aluminum foil and the second resin layer from which the easily peelable aluminum foil laminate has been peeled are placed in water, or a method in which a washing liquid is showered.

[0094] The washing liquid is not particularly limited, and organic solvents such as water, ethanol, toluene, ketones, and esters can be used alone or in mixtures. Additives such as surfactants and neutralizing agents may also be added as needed. Washing with water is preferred. Furthermore, when the first separation step described below is carried out, washing with a gravity separation liquid may also be used. (Second separation step S38)

[0095] The separation and recovery method of the present invention may include a second separation step between the second washing step S35 and the second dehydration step S38, in which the second aluminum foil and the second resin layer are separated by gravity separation. The liquid that can be used for gravity separation may be water, an aqueous solution, or a heavy liquid, and is selected appropriately depending on the desired specific gravity. The gravity separation liquid may also be a washing liquid. The second separation step S38 is performed in the same manner as the first separation step S26, but the gravity separation liquid may be the same or different from that used in the first separation step S26. A gravity separation liquid with a desired specific gravity can be selected to separate the second aluminum foil and the second resin layer. (Second dehydration step S38)

[0096] The second dehydration step S38 is a step of removing the diluted stripping solution and cleaning solution adhering to the second aluminum foil and the second resin layer peeled from the easily peelable aluminum foil laminate, but when the second separation step S36 is included, it may be a step of recovering the precipitated second aluminum foil and removing the specific gravity separation liquid adhering to the second aluminum foil. The dehydration method is not particularly limited, and may be, for example, dehydration by centrifugal dehydration.

[0097] This method for separating and recovering aluminum foil laminates allows the first aluminum foil and first resin layer obtained by peeling off the hard-to-peel aluminum foil laminate, and the second aluminum foil and second resin layer obtained by peeling off the easy-to-peel aluminum foil laminate, to be individually recovered and reused. [Examples and Comparative Examples] [Example]

[0098] The features of the present invention will be further clarified below by showing examples and comparative examples. [Example 1] (Creation of a hard-to-peel aluminum foil laminate)

[0099] For the aluminum foil, a 45 μm thick 8021 material (manufactured by Toyo Aluminum Co., Ltd.) was used. Next, a urethane adhesive was used as the adhesive, and a base agent (manufactured by Toyo Ink Co., Ltd.: base agent TMK-55, solid content 30 mass %) and a curing agent (CAT56-3K, solid content 70 mass %) were prepared, and 100 parts by weight, 10 parts by weight, and 40 parts by weight of the base agent, curing agent, and ethyl acetate were mixed until the color became uniform, to prepare a 25 mass % urethane resin mixed solution.

[0100] The mixed solution was mixed immediately before coating, and the weight after drying with bar coater #16 was 5.0 g / m 2 The mixture was applied to the glossy surface of the aluminum foil so that the coating was as follows: and dried at 100°C for 40 seconds.

[0101] Next, a 20 μm thick stretched polypropylene film (Futamura Chemical Co., Ltd.: FOR) was laminated using a small laminator at a nip temperature of 90° C. and a speed of 5 m / min.

[0102] Furthermore, a urethane adhesive was applied to the matte side of the aluminum foil in the same manner as the glossy side, and then dried. A 15 μm thick nylon film (Bonyl RX, manufactured by Kohjin Film & Chemicals Co., Ltd.) was then attached, and the film was cured at 40°C for 4 days to produce a non-peelable aluminum foil laminate. (Creation of easily peelable aluminum foil laminate)

[0103] The aluminum foil used was a 20 μm thick 1N30 material (manufactured by Toyo Aluminum Co., Ltd.). Next, a nitrocellulose-based coating agent (manufactured by DIC Graphics Corporation: SF1009 Clear NT, solid content 20% by mass) was applied to the glossy side of the aluminum foil using a bar coater #18 so that the weight after drying was 5.0 g / m 2A resin layer was formed by applying the coating solution to the surface of the aluminum foil so that the coating amount was 5.0 g / m2 and drying at 150 ° C. for 1 minute. A vinyl chloride vinyl acetate copolymer coating agent (Leader Corporation: LD#S837G Clear, solid content 21% by mass) was then applied to the poppy side of the aluminum foil using bar coater #18 so that the weight after drying was 5.0 g / m2 and dried at 150 ° C. for 1 minute to form a resin layer. An easily peelable aluminum foil laminate was produced. (Preparation of stripping solution)

[0104] A stripping solution was prepared by adding 45 g of formic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 20 g of butyl acetate (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 25 g of purified water (AS ONE Corporation, ASSWS-20), and 10 g of methyl ethyl ketone (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade) to a 100 mL glass bottle and stirring at room temperature for 10 minutes.

[0105] The hard-to-peel aluminum foil laminate was cut into a size of 20 × 20 mm. Next, 100 g of the prepared peeling solution was measured into a 100 mL glass bottle (mouth inner diameter × body diameter × height: φ31.9 × φ48.5 × 87 mm). 10 pieces of the hard-to-peel aluminum foil laminate cut into the glass bottle and one rotor (As One Corporation, tapered shape, length 25 mm, diameter 8 mm, material PTFE) were placed in the glass bottle, and the glass bottle containing the peeling solution was placed in a single heating and stirring dry bath (As One Corporation: HDBS-6). The glass bottle was heated for 60 minutes while stirring at 60 ° C. and 200 rpm to promote peeling of the aluminum foil and resin (first peeling step). The time until at least 5 of the 10 hard-to-peel aluminum foil laminates introduced were peeled into the aluminum foil and resin layer was measured.

[0106] Next, 95 g of the stripping solution was weighed out and removed from the glass bottle (first preliminary dehydration step). Next, 45 g of purified water was added to the glass bottle to dilute the stripping solution 10 times (dilution step). Next, the aluminum foil and resin layer were separated from the diluted stripping solution by filtration using filter paper (recovery step), and then dried at 100°C for 1 hour (first dehydration step).

[0107] The easily peelable aluminum foil laminate was cut into a size of 20 × 20 mm. Next, about 50 g of the diluted peeling solution recovered in the first washing step described above was weighed into a 100 mL glass bottle (mouth inner diameter × body diameter × height: φ31.9 × φ48.5 × 87 mm). 10 easily peelable aluminum foil laminates cut into the glass bottle and one rotor (As One Corporation, tapered shape, length 25 mm, diameter 8 mm, material PTFE) were placed in the glass bottle, and the glass bottle containing the diluted peeling solution was placed in a single heating and stirring dry bath (As One Corporation: HDBS-6). The glass bottle was heated for 60 minutes while stirring at 60 ° C. and 200 rpm to promote peeling of the aluminum foil and resin (second peeling step). The time until 5 or more of the 10 easily peelable aluminum foil laminates introduced were peeled into the aluminum foil and resin layer was measured.

[0108] Next, the aluminum foil and the resin layer were separated by filtration using filter paper (draining step), washed with purified water (second washing step), and dried at 100° C. for 1 hour (second dehydration step). [Example 2]

[0109] A 100 mL glass bottle was charged with 22.5 g of formic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 22.5 g of acetic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 20 g of butyl acetate (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), and 25 g of purified water (AS ONE Corporation, ASSWS-20), and the mixture was stirred at room temperature for 10 minutes to prepare a stripping solution.

[0110] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. [Example 3]

[0111] A 100 mL glass bottle was charged with 80 g of formic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 5 g of butyl acetate (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 5 g of purified water (AS ONE Corporation, ASSWS-20), and 10 g of methyl ethyl ketone (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), and the mixture was stirred at room temperature for 10 minutes to prepare a stripping solution.

[0112] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. [Example 4]

[0113] A stripping solution was prepared by adding 65 g of formic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 20 g of butyl acetate (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 5 g of purified water (AS ONE Corporation, ASSWS-20), and 10 g of methyl ethyl ketone (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade) to a 100 mL glass bottle and stirring at room temperature for 10 minutes.

[0114] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. [Example 5]

[0115] A stripping solution was prepared by adding 45 g of formic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 40 g of butyl acetate (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 5 g of purified water (AS ONE Corporation, ASSWS-20), and 10 g of methyl ethyl ketone (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade) to a 100 mL glass bottle and stirring at room temperature for 10 minutes.

[0116] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. [Example 6]

[0117] A stripping solution was prepared by adding 20 g of formic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 65 g of butyl acetate (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 5 g of purified water (AS ONE Corporation, ASSWS-20), and 10 g of methyl ethyl ketone (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade) to a 100 mL glass bottle and stirring at room temperature for 10 minutes.

[0118] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. [Example 7]

[0119] A stripping solution was prepared by adding 20 g of formic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 20 g of butyl acetate (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 10 g of purified water (AS ONE Corporation, ASSWS-20), and 50 g of methyl ethyl ketone (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade) to a 100 mL glass bottle and stirring at room temperature for 10 minutes.

[0120] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. [Example 8]

[0121] A stripping solution was prepared by adding 45 g of formic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 5 g of butyl acetate (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), and 50 g of purified water (AS ONE Corporation, ASSWS-20) to a 100 mL glass bottle and stirring at room temperature for 10 minutes.

[0122] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. [Example 9]

[0123] A stripping solution was prepared by adding 15 g of formic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 15 g of butyl acetate (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 1 g of purified water (AS ONE Corporation, ASSWS-20), and 69 g of methyl ethyl ketone (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade) to a 100 mL glass bottle and stirring at room temperature for 10 minutes.

[0124] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. [Example 10]

[0125] A 100 mL glass bottle was charged with 29 g of formic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 1 g of hexyl acetate (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 1 g of purified water (AS ONE Corporation, ASSWS-20), and 69 g of methyl ethyl ketone (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), and the mixture was stirred at room temperature for 10 minutes to prepare a stripping solution.

[0126] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. [Example 11]

[0127] A stripping solution was prepared by adding 98 g of formic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 1 g of hexyl acetate (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), and 1 g of purified water (AS ONE Corporation, ASSWS-20) to a 100 mL glass bottle and stirring at room temperature for 10 minutes.

[0128] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. [Example 12]

[0129] A stripping solution was prepared by adding 15 g of formic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 84 g of butyl acetate (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), and 1 g of purified water (AS ONE Corporation, ASSWS-20) to a 100 mL glass bottle and stirring at room temperature for 10 minutes.

[0130] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. [Example 13]

[0131] A stripping solution was prepared by adding 15 g of formic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 15 g of ethyl acetate (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), and 70 g of purified water (AS ONE Corporation, ASSWS-20) to a 100 mL glass bottle and stirring at room temperature for 10 minutes.

[0132] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. [Example 14]

[0133] A 100 mL glass bottle was charged with 45 g of formic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 20 g of methyl acetate (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 25 g of purified water (AS ONE Corporation, ASSWS-20), and 10 g of methyl ethyl ketone (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), and the mixture was stirred at room temperature for 10 minutes to prepare a stripping solution.

[0134] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. [Example 15]

[0135] 33 g of sodium hydroxide (Fujifilm Wako Pure Chemical Industries, Ltd., granular, special reagent grade) and 77 g of purified water (AS ONE Corporation, ASSWS-20) were placed in a 100 mL PE container and stirred at room temperature for 30 minutes to prepare a 33 wt% aqueous solution of sodium hydroxide. Then, 30 g of phosphoric acid (Fujifilm Wako Pure Chemical Industries, Ltd., Wako Grade 1) and 70 g of purified water (AS ONE Corporation, ASSWS-20) were placed in another 100 mL PE container and stirred at room temperature for 30 minutes to prepare a 30 wt% aqueous solution of phosphoric acid.

[0136] Next, 2.5 g of 30 wt % aqueous phosphoric acid solution (0.8 g of solid content) was added dropwise to 5.3 g of the 33 wt % aqueous sodium hydroxide solution (1.7 g of solid content) in a 100 mL glass bottle while stirring at room temperature, and the mixture was further stirred for 30 minutes to prepare 7.8 g of phosphoric acid-sodium hydroxide buffer solution.

[0137] Furthermore, 38 g of formic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 17 g of butyl acetate (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 20.5 g of purified water (ASSWS-20, AS ONE Corporation) (a total of 25.8 g of purified water including the purified water in the buffer solution), and 16.7 g of methyl ethyl ketone (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade) were added to the glass bottle containing the buffer solution, and the mixture was stirred at room temperature for 30 minutes to prepare a stripping solution.

[0138] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. [Comparative Example 1]

[0139] 33 g of sodium hydroxide (Fujifilm Wako Pure Chemical Industries, Ltd., granular, special reagent grade) and 77 g of purified water (AS ONE Corporation, ASSWS-20) were placed in a 100 mL PE container and stirred at room temperature for 30 minutes to prepare a 33 wt% aqueous solution of sodium hydroxide. Then, 30 g of phosphoric acid (Fujifilm Wako Pure Chemical Industries, Ltd., Wako Grade 1) and 70 g of purified water (AS ONE Corporation, ASSWS-20) were placed in another 100 mL PE container and stirred at room temperature for 30 minutes to prepare a 30 wt% aqueous solution of phosphoric acid.

[0140] Next, 3.0 g (0.9 g solids) of 30 wt% phosphoric acid aqueous solution was added dropwise to 6.3 g (2.1 g solids) of the 33 wt% sodium hydroxide aqueous solution in a 100 mL glass bottle at room temperature while stirring, and the mixture was further stirred for 30 minutes to prepare 9.3 g of phosphoric acid-sodium hydroxide buffer solution.

[0141] Furthermore, 45 g of formic acid (special grade reagent, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 45.7 g of purified water (AS ONE Corporation, ASSWS-20) (52 g in total of purified water including the purified water in the buffer solution) were added to the glass bottle containing the buffer solution, and the mixture was stirred at room temperature for 30 minutes to prepare a stripping solution of composition 2 described in Patent Document 2, which is a current technology.

[0142] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. Comparative Example 2

[0143] A 100 mL PE container was charged with 33 g of sodium hydroxide (Fujifilm Wako Pure Chemical Industries, Ltd., granular, special reagent grade) and 77 g of purified water (AS ONE Corporation, ASSWS-20) and stirred at room temperature for 30 minutes to prepare a 33 wt% sodium hydroxide solution. A separate 100 mL PE container was charged with 30 g of phosphoric acid (Fujifilm Wako Pure Chemical Industries, Ltd., Wako Grade 1) and 70 g of purified water (AS ONE Corporation, ASSWS-20) and stirred at room temperature for 30 minutes to prepare a 30 wt% phosphoric acid solution. Next, 3.0 g of 30 wt% phosphoric acid solution (0.9 g of solids) was added dropwise to 6.3 g of the 33 wt% sodium hydroxide solution (2.1 g of solids) in a 100 mL glass bottle while stirring at room temperature. The mixture was further stirred for 30 minutes to prepare a 9.3 g phosphoric acid-sodium hydroxide buffer solution. Furthermore, 45 g of glacial acetic acid (Fujifilm Wako Pure Chemical Industries, Ltd., 99.7%+%) and 45.7 g of purified water (AS ONE Corporation, ASSWS-20) (52 g in total of purified water including the purified water in the buffer solution) were added to the glass bottle containing the buffer solution, and the mixture was stirred at room temperature for 30 minutes to prepare a stripping solution.

[0144] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. Comparative Example 3 A stripping solution was prepared by adding 100 g of formic acid (special grade reagent, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to a 100 mL glass bottle.

[0145] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. Comparative Example 4

[0146] A stripping solution was prepared by adding 90 g of formic acid (special grade reagent, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 10 g of purified water (AS ONE Corporation, ASSWS-20) to a 100 mL glass bottle and stirring at room temperature for 10 minutes.

[0147] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. Comparative Example 5

[0148] A stripping solution was prepared by adding 14 g of formic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 15 g of methyl acetate (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), and 71 g of purified water (AS ONE Corporation, ASSWS-20) to a 100 mL glass bottle and stirring at room temperature for 10 minutes.

[0149] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. Comparative Example 6

[0150] A stripping solution was prepared by adding 45 g of formic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 20 g of heptyl acetate (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), and 35 g of purified water (AS ONE Corporation, ASSWS-20) to a 100 mL glass bottle and stirring at room temperature for 10 minutes.

[0151] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out. Comparative Example 7

[0152] A stripping solution was prepared by adding 14 g of formic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), 85 g of methyl acetate (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), and 1 g of purified water (AS ONE Corporation, ASSWS-20) to a 100 mL glass bottle and stirring at room temperature for 10 minutes.

[0153] Next, in the same manner as in Example 1, the first peeling step, dilution step, recovery step, first dehydration step, second peeling step, drainage step, second washing step, and second dehydration step were carried out.

[0154] (Evaluation test) In the first peeling step, the time until the hard-to-peel aluminum foil laminate peeled into the aluminum foil and the resin layer (stretched polypropylene film) was measured, and the resin layer peeled within 30 minutes was evaluated as ◎, the resin layer peeled within 45 minutes was evaluated as ◯, the resin layer peeled within 60 minutes was evaluated as △, and the resin layer did not peel even after 60 minutes was evaluated as ×. Table 1 shows the compositions of the stripping solutions of Examples 1 to 15 and Comparative Examples 1 to 8 and the evaluation results for each.

[0155] [Table 1]

[0156] In the second peeling step, the time until the easily peelable aluminum foil laminate was peeled off into the aluminum foil and the resin layer was measured, and the resin layer peeled off within 60 minutes was evaluated as ◯, and the resin layer did not peel off even after 60 minutes was evaluated as ×. Table 1 shows the compositions of the stripping solutions of Examples 1 to 15 and Comparative Examples 1 to 8 and the evaluation results for each.

[0157] [Table 2] <Consideration>

[0158] Comparing Examples 1 to 15 and Comparative Examples 1 to 8 shown in Tables 1 and 2, the stripping solutions of Examples 1 to 15 contain formic acid at 15 wt% to 98 wt%, carboxylic acid ester at 1 wt% to 84 wt%, and water at 1 wt% to 70 wt%, and the sum of the contents of the formic acid and the carboxylic acid ester is 30 wt% to 99 wt%, and the sum of the contents of the formic acid, the carboxylic acid ester, and water is 100 wt% or less. In the evaluation test, it was found that excellent separation effect of the hard-to-peel aluminum foil laminate was exhibited. Furthermore, it was found that excellent separation effect was exhibited by applying the diluted stripping solution to the peeling process of the easy-to-peel aluminum foil laminate.

[0159] Therefore, the separation and recovery method of the present invention makes it possible to quickly separate aluminum foil laminates in a manner that places a low burden on the environment.

Claims

1. A method for separating and recovering an aluminum foil laminate in which an aluminum foil and a resin layer are laminated, into the aluminum foil and the resin layer, (1) A first peeling step in which a hard-to-peel aluminum foil laminate having a resin layer thickness of more than 7 μm is contacted with a stripping solution to peel it into a first aluminum foil and a first resin layer; and a dilution step in which at least a portion of the stripping solution is diluted with water from 5 to 20 times to obtain a diluted stripping solution. (2) A second peeling step in which an easily peelable aluminum foil laminate having a resin layer thickness of 7 μm or less is contacted with the diluted peeling solution to peel it into a second aluminum foil and a second resin layer; Each of these is provided in order, The stripper solution Contains formic acid in an amount of 15 wt% or more and 98 wt% or less, containing 1 wt % or more and 84 wt % or less of one or more carboxylic acid esters selected from the group consisting of methyl formate, ethyl formate, propyl formate, butyl formate, pentyl formate, hexyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, pentyl acetate, and hexyl acetate, The separation and recovery method is characterized in that the mixture contains water in an amount of 1 wt % or more and 70 wt % or less, the sum of the contents of the formic acid and the carboxylic acid ester is 30 wt % or more and 99 wt % or less, and the sum of the contents of the formic acid, the carboxylic acid ester, and the water is 100 wt % or less.

2. The diluted stripping solution in the second stripping step is Contains 1.5 wt% or more and 9.8 wt% or less of formic acid, containing 0.1 wt % or more and 8.4 wt % or less of one or more carboxylic acid esters selected from the group consisting of methyl formate, ethyl formate, propyl formate, butyl formate, pentyl formate, hexyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, pentyl acetate, and hexyl acetate, 2. The separation and recovery method according to claim 1, wherein the mixture contains 10 wt % or more and 97 wt % or less of water, the sum of the contents of the formic acid and the carboxylic acid ester is 3 wt % or more and 9.9 wt % or less, and the sum of the contents of the formic acid, the carboxylic acid ester, and the water is 100 wt % or less.

3. The separation and recovery method according to claim 1, characterized in that the hard-to-peel aluminum foil laminate is crushed before the first peeling step and / or the easy-to-peel aluminum foil laminate is crushed before the second peeling step.

4. The separation and recovery method according to claim 1 , further comprising a recovery step of recovering the diluted stripping solution after the dilution step.

5. 5. The separation and recovery method according to claim 4, further comprising a first cleaning step of cleaning the first aluminum foil and the first resin layer with a cleaning liquid after the recovery step, and a first dehydration step of removing the cleaning liquid adhering to the first aluminum foil and the first resin layer.

6. 6. The separation and recovery method according to claim 5, further comprising, in sequence, a draining step of discharging a diluted stripping solution, a second cleaning step of cleaning the second aluminum foil and the second resin layer with a cleaning solution, and a second dehydration step of removing the cleaning solution adhering to the second aluminum foil and the second resin layer, after the second peeling step.

7. 2. The separation and recovery method according to claim 1, further comprising a first preliminary dehydration step between the first stripping step and the dilution step, for removing a predetermined amount of the stripping solution.

8. A first separation step of separating the first aluminum foil and the first resin layer by a gravity separation method between the first washing step and the first dehydration step, and / or a second separation step of separating the second aluminum foil and the second resin layer by a gravity separation method between the second washing step and the second dehydration step. The separation and recovery method according to any one of claims 1 to 7, characterized in that it comprises:

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