Laminate and method for producing recovered aluminum

Abstract

To provide a laminate in which aluminum foil and a plastic base material are laminated and from which aluminum can be separated and recovered with a basic aqueous solution in a high yield, and to provide a method for producing recycled aluminum.SOLUTION: A laminate comprising at least one plastic substrate, a release layer, and a separation layer in this order, wherein the separation layer comprises a first polymer layer, an aluminum foil, and a second polymer layer in this order, the release layer is a peelable polymer layer composed of a material having an acid number higher than an acid number of a material constituting the inorganic material-deposited layer and / or the first polymer layer and higher than an acid number of a material constituting the second polymer layer, and when the laminate is cut into 1cm * 1cm and statically immersed in a 1% by mass sodium hydroxide aqueous solution at 60 °C for 6 hours, the aluminum foil-containing laminate including the separation layer can be separated and recovered by peeling off the release layer from the plastic substrate.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminate and a method for producing recovered aluminum. [Background technology]

[0002] Aluminum is a widely used recyclable material. However, recycling aluminum in laminates, such as packaging with aluminum foil between multiple layers, requires a more complex process than conventional aluminum product recycling, as it must first be separated from other materials, such as plastics.

[0003] Regarding material recycling of such laminates having aluminum foil, for example, Patent Document 1 discloses a technology in which a laminate having an aluminum layer as a detachment layer is treated with a basic aqueous solution to detach the detachment layer and the printed layer from not only surface-printed laminates but also laminates having a multi-layer structure. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-175620 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a multilayer laminate having an aluminum layer is treated with a basic aqueous solution as in the technology described in Patent Document 1, the aluminum layer is dissolved in whole or in part, resulting in an extremely low recovery yield of aluminum. Furthermore, a chemical reaction between the basic component in the basic aqueous solution and aluminum proceeds, and the basic component is consumed with the dissolution of the aluminum layer, reducing the ability of the basic aqueous solution to detach the detachment layer, which was previously possessed by the basic aqueous solution. This also reduces the efficiency of treating the laminate relative to the amount of aqueous solution, making it difficult to recover aluminum. Furthermore, from the viewpoint of recovering plastic substrates, the finely divided aluminum adheres to the plastic substrate, causing discoloration during recycling, which reduces the quality of recycled plastics produced from the recovered plastic substrates. On the other hand, if an attempt is made to recycle the aluminum layer by a known method without peeling it from the laminate, the plastic substrate in the laminate will be incinerated when the aluminum is melted. Therefore, with conventional methods, it has been difficult to recover aluminum at a high yield from a multi-layer laminate having an aluminum layer, and it has been even more difficult to recover the plastic substrate and obtain high-quality recycled plastic.

[0006] An object of the present invention is to provide a laminate and a method for producing recycled aluminum, which can separate and recover aluminum from a laminate in which aluminum foil and a plastic substrate are laminated together with a basic aqueous solution at a high yield. [Means for solving the problem]

[0007] That is, the present invention relates to the following [1] to

[14] .

[0008] [1] A laminate having at least one plastic substrate, a release layer, and a separation layer in this order, the separating layer comprises a first polymer layer, an aluminum foil, and a second polymer layer in this order; the release layer is an inorganic substance vapor deposition layer and / or a releaseable polymer layer made of a material having an acid value higher than that of a material constituting the first polymer layer and higher than that of a material constituting the second polymer layer; When the laminate is cut into 1 cm x 1 cm pieces and immersed in a 1% by mass aqueous solution of sodium hydroxide at 60°C for 6 hours, the peel layer peels off from the plastic substrate, thereby enabling the aluminum foil-containing laminate including the separation layer to be separated and recovered.

[0009] [2] The laminate according to [1], wherein the acid value of the material constituting the first polymer layer or the acid value of the material constituting the second polymer layer is less than 5 mgKOH / g.

[0010] [3] The laminate according to [1], wherein the acid value of the material constituting the first polymer layer and the acid value of the material constituting the second polymer layer are less than 5 mgKOH / g.

[0011] [4] The laminate according to any one of [1] to [3], wherein at least one layer of the plastic substrate contains a polyolefin resin.

[0012] [5] The laminate according to any one of [1] to [4], wherein the first polymer layer and / or the second polymer layer contains one or more resins selected from the group consisting of vinyl chloride-vinyl acetate resin, urethane resin, epoxy resin, and nitrocellulose resin.

[0013] [6] The laminate according to any one of [1] to [5], wherein the first polymer layer and / or the second polymer layer has a structure derived from a crosslinking agent containing one or more selected from the group consisting of an isocyanate-based crosslinking agent, an amino-based crosslinking agent, and a silane coupling agent.

[0014] [7] The laminate according to any one of [1] to [6], wherein the first polymer layer and / or the second polymer layer contains a colorant.

[0015] [8] 8. The laminate according to claim 1, wherein the peelable polymer layer is a cured product of an adhesive containing a polyester polyol and a polyisocyanate.

[0016] [9] The laminate according to any one of [1] to [8], wherein the aluminum foil has a thickness of 5 μm or more.

[0017]

[10] a separation step of contacting the laminate according to any one of [1] to [9] with a basic aqueous solution to peel the release layer from at least one plastic substrate layer, thereby obtaining an aluminum foil-containing laminate including a separation layer; A method for producing recovered aluminum, comprising an aluminum recovery step of obtaining recovered aluminum from the aluminum foil-containing laminate.

[0018]

[11] The manufacturing method according to

[10] , wherein the amount of recovered aluminum relative to the amount of aluminum foil contained in the laminate before the separation step is 70 mass % or more.

[0019]

[12] The method according to

[10] or

[11] , wherein the basic aqueous solution contains an anionic surfactant and / or a nonionic surfactant.

[0020]

[13] The manufacturing method according to any one of

[10] to

[12] , further comprising separating and recovering the plastic substrate to obtain a recovered plastic substrate.

[0021]

[14] The manufacturing method according to

[13] , wherein the amount of the recovered plastic substrate relative to the amount of the plastic substrate contained in the laminate before the separation step is 70 mass % or more. [Effects of the Invention]

[0022] The present invention makes it possible to provide a laminate and a method for producing recycled aluminum, which can separate and recover aluminum with a high yield from a laminate in which aluminum foil and a plastic substrate are laminated together using a basic aqueous solution. DETAILED DESCRIPTION OF THE INVENTION

[0023] The following describes in detail the embodiments of the present invention. However, the following description of the embodiments or requirements is merely an example of an embodiment of the present invention, and the present invention is not limited to these contents as long as it does not exceed the gist of the present invention.

[0024] <Laminate> The laminate of the present invention is a laminate having at least one plastic substrate, a release layer, and a separation layer in this order, wherein the separation layer has a first polymer layer, an aluminum foil, and a second polymer layer in this order, and the release layer is an inorganic vapor deposition layer and / or a peelable polymer layer made of a material having an acid value higher than the acid value of the material constituting the first polymer layer and higher than the acid value of the material constituting the second polymer layer. Furthermore, when the laminate of the present invention is cut into a piece of 1 cm x 1 cm and left to stand in a 1% by mass aqueous solution of sodium hydroxide at 60°C for 6 hours, the peel layer peels off from the plastic substrate, thereby enabling the aluminum foil-containing laminate including the separation layer to be separated and recovered.

[0025] In the present invention, "cutting" refers to adjusting the laminate to a desired size. Cutting can be performed by a known method, and for small amounts, scissors or a utility knife can be used, and for large amounts, a known plastic cutter or crusher can be used. In the present invention, "peeling" refers to the peeling of the release layer from the plastic substrate as a result of the release layer being dissolved or swollen by a basic aqueous solution. In the present invention, "separation and recovery" refers to obtaining an aluminum foil-containing laminate or plastic substrate containing a separation layer in a state in which other components and unpeeled laminate have been selected and removed as much as possible.

[0026] Because the laminate of the present invention has the above-mentioned configuration, when it is contacted with a basic aqueous solution under appropriate conditions, the release layer is peeled off from at least one layer of plastic substrate, and an aluminum foil-containing laminate in which the aluminum foil, the first polymer layer, and the second polymer layer are integrated can be separated and recovered, and as a result, aluminum can be separated and recovered with a high yield. In addition, in a more preferred embodiment of the present invention, in addition to the above, a highly transparent plastic substrate with little aluminum foil mixed in can be separated and recovered with a high yield from a laminate in which aluminum foil and a plastic substrate are laminated.

[0027] <Laminate structure> Examples of laminate structures of the present invention are given below, but the present invention is not limited to these. Furthermore, in the following structures, the "plastic substrate," "release layer," "first polymer layer," and "second polymer layer" do not necessarily have to be single layers, and multiple layers may be laminated. In the following structure descriptions, " / " indicates the boundary between each layer. Plastic substrate / release layer / first polymer layer / aluminum foil / second polymer layer Plastic substrate / release layer / first polymer layer / aluminum foil / second polymer layer / / plastic substrate Plastic substrate / release layer / first polymer layer / aluminum foil / second polymer layer / release layer / plastic substrate

[0028] <Plastic substrate> Examples of plastic substrates that can be used in the laminate of the present invention include polyolefin resins, polyester resins, polyamide resins, polystyrene resins, vinyl chloride resins, vinyl acetate resins, ABS resins, acrylic resins, acetal resins, polycarbonate resins, polyvinyl alcohol resins, and cellulose-based plastics. The plastic substrate may be a single layer or a substrate made of multiple plastic layers, and in the case of multiple plastic layers, an adhesive layer or the like may be interposed between them. In the case of multiple plastic layers, if the plastic substrate has a structure made of similar plastic layers, so-called monomaterial, the recovery and recycling of the plastic substrate becomes easier.

[0029] From the viewpoint of separating and recovering plastic substrates and reusing them as recycled substrates, the plastic substrate is preferably a substrate containing a plastic with a specific gravity of less than 1.2 or less than 1.1, such as nylon, polystyrene, or polyolefin, which has a different sedimentation rate in specific gravity separation from the aluminum foil-containing separation layer and is easy to separate, and is more preferably a polyolefin substrate containing a polyolefin resin. Examples of substrates containing such polyolefin resins include plastic substrates such as polyethylene (PE) and biaxially oriented polypropylene (OPP), as well as sealant substrates such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), acid-modified polyethylene, unstretched polypropylene (CPP), acid-modified polypropylene, and copolymer polypropylene.

[0030] The thickness of the plastic substrate is not particularly limited and may be appropriately selected depending on the application. It is preferably 5 to 1000 μm, and more preferably 10 to 500 μm. The plastic substrate may be laminated with a gas barrier layer or the like, and a vapor-deposited film having an inorganic vapor-deposited layer of metal, silica, alumina, or the like may be used as the gas barrier layer. These inorganic vapor-deposited layers dissolve in a basic aqueous solution and are peeled off from the plastic substrate, so the inorganic vapor-deposited layer also functions as a release layer.

[0031] <Release layer> In an embodiment of the present invention, the release layer is a layer that is arranged in contact with at least one plastic substrate and can be peeled off from the plastic substrate using a known release liquid, and the material that constitutes the release layer is an inorganic vapor deposition layer and / or a peelable polymer layer that has an acid value that is higher than the acid value of the material that constitutes the first polymer layer and is also higher than the acid value of the material that constitutes the second polymer layer. The release layer may be an inorganic vapor deposition layer, a release polymer layer, or may include both an inorganic vapor deposition layer and a release polymer layer. Here, the material constituting the release layer refers to a material constituting a release layer in a dried or hardened state obtained by vapor-depositing, coating, or printing the release layer-forming material on a plastic substrate. The acid value of the material constituting the release polymer layer may be a theoretical value calculated from the formulation of the release layer-forming material.

[0032] (Inorganic vapor deposition layer) The inorganic vapor-deposited layer (hereinafter also referred to as the vapor-deposited layer) is composed of inorganic substances such as aluminum, aluminum oxide, and silica, and can be formed by conventionally known methods, with no particular limitations on its composition or formation method. The vapor-deposited layer is preferably composed of a non-crystalline (amorphous) layer. Furthermore, the vapor-deposited layer is preferably a vapor-deposited layer of one or more inorganic substances selected from the group consisting of aluminum, aluminum oxide, and silica, and the inorganic substance is more preferably aluminum oxide and / or silica from the viewpoint of visible light transmittance, and more preferably aluminum to achieve a form exhibiting light-blocking properties. However, the presence of elements or compounds other than aluminum, aluminum oxide, and silica during vapor deposition is not excluded. The inorganic vapor-deposited layer may have two or more vapor-deposited layers. When two or more vapor-deposited layers are present, the layers may have the same composition or different compositions. When the packaging material has a vapor-deposited layer, the vapor-deposited layer also functions as an oxygen and / or water vapor barrier layer before being subjected to a peeling treatment using a basic aqueous solution.

[0033] The vapor-deposited layers made of aluminum oxide and silica preferably contain Al2O3 and SiO2, respectively. For example, when aluminum oxide is expressed as AlOn and silica as SiOn, the value of n may be in the range of 0.5 to 1.5 for aluminum oxide and in the range of 1 to 2 for silica, and this does not exclude forms of aluminum oxide or silica other than Al2O3 and SiO2. On the other hand, from the viewpoint of light-blocking properties, the vapor-deposited layer made of aluminum is preferably a vapor-deposited film made substantially of aluminum only.

[0034] The thickness of the vapor-deposited film is usually in the range of 1 to 400 nm, preferably in the range of 5 to 300 nm, and more preferably in the range of 10 to 200 nm.

[0035] When the inorganic substance constituting the vapor-deposited layer is aluminum, the thickness is preferably 5 to 300 nm, more preferably 10 to 100 nm, and even more preferably 10 to 60 nm. When the inorganic substance constituting the vapor-deposited layer is aluminum oxide and / or silica, the thickness is preferably 5 to 300 nm, more preferably 10 to 100 nm, and even more preferably 10 to 60 nm. The thickness of the vapor-deposited film can be measured by the fundamental parameter method using, for example, an X-ray fluorescence analyzer manufactured by Hitachi High-Tech Science Corporation (model names: EA6000VX or EA8000).

[0036] (Formation of vapor deposition layer) Suitable methods for forming the vapor deposition layer include, for example, physical vapor deposition methods (PVD methods) such as vacuum deposition, sputtering, and ion plating; and chemical vapor deposition methods (CVD methods) such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition. Commercially available plastic substrates having such a vapor deposition layer include, for example, "GL FILM" (manufactured by Toppan Printing Co., Ltd.) and IB-FILM (manufactured by Dai Nippon Printing Co., Ltd.), which have a vapor deposition layer of alumina or the like laminated on a first substrate.

[0037] The vapor-deposited layer may further have an easy-adhesion layer. The easy-adhesion layer is preferably an easy-adhesion layer containing one or more resins selected from a polyurethane resin layer, an acrylic resin layer, a polyester resin, and a polyvinyl alcohol, and the resin is more preferably aqueous. The easy-adhesion layer can be formed by printing or other known methods.

[0038] (Releasable polymer layer) The release polymer layer of the present invention is formed from a release layer-forming material containing a polymer. The release layer-forming material can be in the form of a varnish, ink, adhesive, or other known material that can be peeled from a plastic substrate in a layered state using a basic aqueous solution. That is, the release polymer layer is a layer containing a compound having an acidic group that promotes peeling using a basic aqueous solution while maintaining the water resistance of the laminate. Furthermore, the acid value of the material that constitutes the release polymer layer is higher than the acid value of the material that constitutes the first polymer layer and is also higher than the acid value of the material that constitutes the second polymer layer. Here, when each layer is made of a plurality of materials, the acid value of the material constituting each layer is a value determined for a mixture of the materials.

[0039] It is presumed that the presence of a compound having an acidic group in the release polymer layer allows the release liquid to penetrate more easily, making the release polymer layer more likely to swell, thereby significantly accelerating the release of the release layer.

[0040] (Compounds with an acidic group) The compound having an acidic group may be a resin or a low molecular weight compound. One type of compound having an acidic group may be used alone, or two or more types may be used in combination. Examples of resins having an acidic group include water-soluble resins having an acidic group and water-insoluble resins having an acidic group.

[0041] Examples of resins having an acidic group include cellulose resins, urethane resins, polyamide resins, vinyl chloride / vinyl acetate copolymers, ketone resins, polyester resins, and (meth)acrylic resins. Examples of the acidic group include a carboxy group, a phosphate group, a sulfo group, a sulfino group, or an ester or salt thereof, and urethane resins are preferred. Furthermore, as the resin having an acidic group, a rosin-modified resin having an acid value, such as maleic rosin or fumaric rosin, can be used. Furthermore, examples of resins having an acidic group that can be used include radical copolymers such as styrene-(meth)acrylic resin, styrene-maleic (anhydride) resin, and terpene-maleic (anhydride) resin, which are copolymerized with polymerizable monomers having an acidic group, such as polymerizable monomers having a carboxy group, such as itaconic acid, maleic acid, fumaric acid, and cinnamic acid; polymerizable monomers that are acid anhydrides, such as itaconic acid anhydride and maleic acid anhydride; polymerizable monomers having a sulfonic acid group, such as sulfonated styrene; and polymerizable monomers having a sulfonamide group, such as vinylbenzenesulfonamide; and acid-modified polyolefin resins. These may be used alone or in combination of two or more.

[0042] A low-molecular-weight compound having an acidic group refers to a compound that does not have a molecular weight distribution and has a molecular weight of 1,000 or less. Examples of such compounds include saturated fatty acids such as lauric acid, myristic acid, palmitic acid, margaric acid, and stearic acid; unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, and sorbic acid; hydroxy acids such as lactic acid, malic acid, and citric acid; aromatic carboxylic acids such as benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, mellitic acid, and cinnamic acid; dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, and maleic acid; tricarboxylic acids such as aconitic acid; oxocarboxylic acids such as pyruvic acid and oxaloacetic acid; carboxylic acid derivatives such as amino acids and nitrocarboxylic acids; and acid anhydrides such as trimellitic anhydride and pyromellitic anhydride. The low molecular weight compound having an acidic group can be used in combination with the above-mentioned resin having an acidic group or a known binder resin that constitutes the release polymer layer to form the release polymer layer.

[0043] From the viewpoint of adhesiveness to the plastic substrate and aluminum foil, the peelable polymer layer preferably contains a urethane resin and / or a polyolefin resin having an acidic group, and more preferably contains a urethane resin having stronger adhesiveness. The peelable polymer layer may contain one of these resins alone or two or more of them in combination.

[0044] [Urethane resin having an acidic group] The urethane resin having an acidic group is not particularly limited, and examples thereof include a urethane resin obtained by reacting a polyol having an acidic group with a polyisocyanate, a resin obtained by acid-modifying the hydroxyl groups in a urethane resin obtained by reacting a polyol with a polyisocyanate, and a resin obtained by acid-modifying the amino groups in a urethane urea resin obtained by reacting a polyamine with the isocyanate groups in a urethane resin obtained by reacting a polyol with a polyisocyanate. Furthermore, as the urethane resin having an acidic group, a resin obtained by reacting a polyol containing a hydroxy acid with a polyisocyanate may be used. By using a hydroxy acid as the polyol, an acid value derived from a carboxy group can be imparted to the urethane resin, thereby improving the releasability. Furthermore, when the urethane resin having an acidic group has an isocyanate group, a polyamine may be reacted with a portion of the isocyanate group to introduce a urea bond, thereby forming a urethane urea.

[0045] <Polyol> Polyol is a general term for compounds having at least two hydroxyl groups in one molecule. The number-average molecular weight of the polyol is preferably 500 to 10,000, more preferably 1,000 to 5,000. The number-average molecular weight is calculated from the hydroxyl value of the polyol, and the hydroxyl value refers to a value measured according to JIS K 0070. When the number-average molecular weight of the polyol is 500 or more, the flexibility of the release polymer layer is excellent and the adhesion to plastic substrates is improved. When the number-average molecular weight is 10,000 or less, the blocking resistance to plastic substrates is excellent.

[0046] The polyol is not particularly limited, and more preferably, at least one polyol selected from the group consisting of polyester polyols, polyether polyols, and polycarbonate polyols is used. The polyol may further include other polyols such as dimer diols, hydrogenated dimer diols, and castor oil-modified polyols. That is, the urethane resin preferably contains a structural unit derived from at least one polyol selected from the group consisting of polyester polyol, polyether polyol, and polycarbonate polyol, and more preferably contains a structural unit derived from a polyester polyol, since alkaline hydrolysis of the ester bond site of the polyester polyol improves releasability. The content of the polyol-derived structural units is preferably 10 to 75 mass%, more preferably 15 to 70 mass%, and even more preferably 20 to 65 mass%, based on the total amount of the urethane resin. The content of the polyester polyol-derived structural units is preferably 5 mass% or more, more preferably 30 mass% or more, even more preferably 60 mass% or more, and particularly preferably 80 mass% or more, based on the total amount of the polyol-derived structural units.

[0047] Hydroxy acids The polyol may contain a hydroxy acid. The hydroxy acid refers to a compound having both a hydroxyl group, which is an active hydrogen group, and an acidic functional group in one molecule. The acidic functional group refers to a functional group that can be neutralized with potassium hydroxide when measuring the acid value, and specific examples include a carboxy group and a sulfonic acid group, with a carboxy group being preferred. As such a hydroxy acid, for example, a dimethylolalkanoic acid such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, or 2,2-dimethylolvaleric acid is preferably used.

[0048] <Polyisocyanate> The polyisocyanate is not particularly limited and can be selected from conventionally known polyisocyanates. Preferably, it contains a diisocyanate or triisocyanate, and more preferably, it contains an aromatic, aliphatic, or alicyclic diisocyanate. These may be used alone or in combination of two or more.

[0049] Polyamines The polyamine for forming the urethane urea is not particularly limited, but is preferably a diamine compound. Furthermore, a diamine having a hydroxyl group may be used because it can introduce a hydroxyl group into the urethane resin. Examples of diamines include ethylenediamine, propylenediamine, hexamethylenediamine, pentamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, and p-phenylenediamine. Examples of diamines having a hydroxyl group include 2-hydroxyethylethylenediamine, 2-hydroxyethylpropyldiamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine.

[0050] The acid value of the urethane resin having an acidic group is preferably 15 mgKOH / g or more, more preferably 15 to 70 mgKOH / g, and even more preferably 20 to 50 mgKOH / g. An acid value of 15 mgKOH / g or more is preferable because it improves removability with a basic aqueous solution, and an acid value of 70 mgKOH / g or less is preferable because it improves substrate adhesion and retort resistance. The hydroxyl value of the urethane resin is preferably 1 to 35 mgKOH / g, more preferably 10 to 30 mgKOH / g. A hydroxyl value of 1 mgKOH / g or more is preferred because it improves removability with a basic aqueous solution, and a hydroxyl value of 35 mgKOH / g or less is preferred because it improves adhesion to substrates.

[0051] The weight-average molecular weight of the urethane resin having an acidic group is preferably 10,000 to 100,000, more preferably 15,000 to 70,000, and even more preferably 15,000 to 50,000. The molecular weight distribution (Mw / Mn) of the urethane resin is preferably 6 or less. Mw represents the weight-average molecular weight, and Mn represents the number-average molecular weight. When the molecular weight distribution is 6 or less, the release properties, drying properties of the release layer-forming material, and retort resistance may be excellent. Furthermore, the smaller the molecular weight distribution, i.e., the sharper the molecular weight distribution, the more uniform the dissolution or release action by a basic aqueous solution, and the more improved the release properties of the release layer. The molecular weight distribution is more preferably 5 or less, and even more preferably 4 or less. Furthermore, the molecular weight distribution is preferably 1.5 or more, and more preferably 1.2 or more. In the present invention, Mw, Mn and molecular weight distribution (Mw / Mn) are values ​​calculated in terms of polystyrene obtained by gel permeation chromatography (GPC).

[0052] The urethane resin having an acidic group may have an amino group. When the urethane resin has an amino group, the amine value is preferably 0.1 to 20 mgKOH / g, more preferably 1 to 10 mgKOH / g. When the amine value is within the above range, excellent adhesion to substrates may be obtained.

[0053] The number of urethane bonds in the polyurethane resin having acidic groups is preferably 1 to 3 mmol / g, more preferably 1.5 to 2 mmol / g. The number of urea bonds is preferably 0 to 3 mmol / g, more preferably 0.2 to 1 mmol / g. The total number of urethane bonds and urea bonds is preferably 1 to 6 mmol / g, more preferably 1.7 to 3 mmol / g. By setting the number of urethane bonds and the number of urea bonds within the above ranges, the releasability and the ability to prevent re-adhesion to plastic substrates may be improved.

[0054] [Polyolefin resin having acidic groups] As the polyolefin resin having an acidic group, commercially available known resins can be used. Specific examples include maleic anhydride-modified polypropylene, ethylene-(meth)acrylic acid copolymer, ethylene-acrylic acid ester-maleic anhydride terpolymer, and ethylene-methacrylic acid ester-maleic anhydride terpolymer. Specific examples are commercially available as "Modic" manufactured by Mitsubishi Chemical Corporation, and "Admer" and "Unistall" manufactured by Mitsui Chemicals, Inc.

[0055] (Other ingredients) The release polymer layer may contain a resin other than the compound having an acidic group. Examples of such resins include cellulose resins, polyamide resins, vinyl chloride resins such as vinyl chloride-vinyl acetate copolymer resins and vinyl chloride-acrylic copolymer resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, acrylic resins, styrene resins, dammar resins, styrene-acrylic copolymer resins, polyester resins, alkyd resins, terpene resins, phenol-modified terpene resins, ketone resins, cyclized rubbers, chlorinated rubbers, butyral, polyacetal resins, petroleum resins, and modified resins thereof. These resins may be used alone or in combination of two or more. Among these, the release layer preferably contains at least one resin selected from the group consisting of cellulose resin, vinyl chloride resin, rosin resin, and acrylic resin, and more preferably contains vinyl chloride resin and / or acrylic resin. The mass ratio of the resin having an acidic group to the other resin (resin having an acidic group:other resin) is preferably 95:5 to 50:50 from the viewpoint of maintaining good releasability.

[0056] The release polymer layer may further contain known extender pigments and additives. Known extender pigments include, for example, silica, barium sulfate, kaolin, clay, calcium carbonate, magnesium carbonate, zinc oxide, zirconium oxide, and other metal oxides. Among these, silica is preferred, and hydrophilic silica is more preferred. Examples of known additives include dispersants, wetting agents, adhesion aids, leveling agents, antifoaming agents, antistatic agents, viscosity modifiers, metal chelates, trapping agents, antiblocking agents, and wax components other than those mentioned above.

[0057] The thickness of the peelable polymer layer is preferably in the range of 0.1 to 10.0 μm, more preferably 0.3 to 7.0 μm, and even more preferably 0.5 to 5.0 μm, and can be formed using a known method.

[0058] When the release layer-forming material forming the release polymer layer is in the form of an adhesive, the release polymer layer is preferably a cured product of an adhesive containing a polyol and a polyisocyanate. The cured product corresponds to the resin having an acidic group. In this case, the release polymer layer may be a cured product of an adhesive containing a polyester polyol having an acidic group and a polyisocyanate, or a cured product of an adhesive containing a polyester polyol, a polyisocyanate, and a low-molecular-weight compound having an acidic group.

[0059] <Separation layer> The separation layer has a first polymer layer, an aluminum foil, and a second polymer layer in this order, and is in contact with the above-mentioned release layer. The separation layer is separated from the plastic substrate by peeling the above-mentioned release layer with a basic aqueous solution. This results in an aluminum foil-containing laminate including a separation layer. In the separation layer, the first polymer layer and the second polymer layer coat both sides of the aluminum foil. Hereinafter, the first polymer layer and the second polymer layer may be collectively referred to simply as "polymer layer".

[0060] <First polymer layer, second polymer layer> In an embodiment of the present invention, the polymer layer is disposed in contact with the aluminum foil. The polymer layer is a layer that prevents the aluminum foil from being dissolved in a basic aqueous solution. When the release layer is a release polymer layer, the acid values ​​of the materials constituting the first polymer layer and the second polymer layer must be lower than the acid value of the material constituting the release polymer layer. Here, the materials constituting the first polymer layer and the second polymer layer refer to materials constituting the polymer layer in a dried or cured state by applying, printing, or extrusion laminating the polymer layer-forming material. The acid values ​​of the materials constituting the first polymer layer and the second polymer layer may be theoretical values ​​calculated from the formulation of the polymer layer-forming material. When calculating the theoretical value, the calculation is performed assuming that the polymer layer-forming material is applied, printed, or extrusion laminated, and then dried or cured.

[0061] The first polymer layer and the second polymer layer in the present invention are formed from a polymer layer-forming material, which can be in the form of varnish, ink, adhesive, or the like. The acid value of the material constituting the first polymer layer or the material constituting the second polymer layer is preferably less than 5 mgKOH / g, and more preferably less than 5 mgKOH / g. If the acid value of the material constituting the first polymer layer and / or the material constituting the second polymer layer is less than 5 mgKOH / g, dissolution of the aluminum foil by the basic aqueous solution used when peeling the laminate can be further suppressed, thereby increasing the aluminum recovery rate.

[0062] In view of adhesion to aluminum foil and physical properties when the laminate is used as a packaging material, the first polymer layer and the second polymer layer preferably contain one or more resins selected from the group consisting of vinyl chloride-vinyl acetate resin, urethane resin, epoxy resin, and nitrocellulose resin. These resins are suitably used as binder resins for varnishes, inks, adhesives, etc., and a polymer layer can be formed by coating or printing a polymer layer-forming material containing these known resins.

[0063] The thickness of the first polymer layer and the second polymer layer formed by coating or printing can be adjusted as appropriate depending on the function of the polymer layer, such as coloring or adhesion, but from the viewpoint of protecting the aluminum foil from the basic aqueous solution and the adhesion of the formed layer to the aluminum foil, the thickness is preferably about 0.3 μm to 10 μm, more preferably 0.5 μm to 5 μm.

[0064] When the first polymer layer and the second polymer layer are formed by extrusion lamination, a known method can be applied in which, for example, a polymer layer forming material containing a molten polyolefin resin or the like is extruded using an extruder, extruded into a film using a jig called a T-die, and then pressed and laminated with an aluminum layer using a press roll and a cooling roll.

[0065] The resin contained in the polymer layer forming material used for extrusion lamination can be appropriately selected from known polyolefin resins, etc. From the viewpoint of processability, a resin having a density of 0.85 to 0.93 g / cm 3 A low-density polyethylene having a melt flow rate (MFR) of 1 to 30 g / 10 min is preferably used. The melting temperature of the polymer layer-forming material can be adjusted by the melt flow rate of the resin contained, and from the viewpoint of adhesive strength, it is preferably 270° C. or higher immediately below the T-die extrusion, more preferably 290° C. or higher. Commercially available examples of such polyolefin resins include the Novatec LD series (manufactured by Japan Polyethylene Corporation), the Pedrosene series (manufactured by Tosoh Corporation), and the Novatec PP series (manufactured by Japan Polypropylene Corporation). These polyolefin resins may be used alone or in combination of two or more. The thickness of the polymer layer formed by extrusion lamination is preferably 10 μm to 50 μm, more preferably 10 μm to 30 μm, from the viewpoint of achieving good adhesive strength.

[0066] <Crosslinking agent> When the polymer layer is formed by coating or printing, the polymer layer-forming material preferably contains a crosslinking agent, and the crosslinking agent preferably contains one or more crosslinkers selected from the group consisting of isocyanate-based crosslinking agents, amino-based crosslinking agents, and silane coupling agents. These crosslinking agents crosslink within the polymer layer formed by coating or printing, improving durability to basic aqueous solutions and thereby further suppressing dissolution of the aluminum foil in basic aqueous solutions. These crosslinking agents can be mixed in any ratio and used immediately before coating or printing the polymer layer-forming material.

[0067] (Isocyanate-based crosslinking agent) The isocyanate-based crosslinking agent is not particularly limited and can be selected from conventionally known agents, such as aliphatic polyisocyanates and araliphatic polyisocyanates. These may be used alone or in combination of two or more.

[0068] As the aliphatic polyisocyanate, well-known aliphatic diisocyanates, alicyclic diisocyanates, araliphatic diisocyanates, or derivatives thereof can be used. Examples of aliphatic diisocyanates include aliphatic diisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, and 2,6-diisocyanate methyl caproate; 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), and methyl ... alicyclic diisocyanates such as methyl 2,4-cyclohexane diisocyanate, methyl 2,6-cyclohexane diisocyanate, 1,4-bis(isocyanatomethyl)cyclohexane, and 1,3-bis(isocyanatomethyl)cyclohexane; araliphatic diisocyanates such as 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω,ω'-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene or a mixture thereof; and polyisocyanates such as allophanate, nurate, biuret, and adduct derivatives derived from the above diisocyanates, or complexes thereof.

[0069] As the aromatic polyisocyanate, well-known aromatic diisocyanates or derivatives thereof can be used. Examples of aromatic diisocyanates include toluene diisocyanate, diphenylmethane diisocyanate, and allophanate, nurate, biuret, and adduct derivatives derived from the above diisocyanates, or complexes thereof.

[0070] The polyisocyanate is preferably an adduct polyisocyanate (hereinafter referred to as an adduct), biuret polyisocyanate (hereinafter referred to as a biuret), or isocyanurate polyisocyanate (hereinafter referred to as an isocyanurate) of tolylene diisocyanate (hereinafter referred to as TDI), diphenylmethane diisocyanate (hereinafter referred to as MDI), or hexamethylene diisocyanate (hereinafter referred to as HDI), and more preferably a trimethylolpropane adduct (HDI-TPM), biuret, or isocyanurate derived from hexamethylene diisocyanate.

[0071] (Amino-based crosslinking agent) The amino-based crosslinking agent is not particularly limited and can be selected from conventionally known crosslinking agents, such as melamine compounds, alkylated ureas, and benzoguanamine compounds. These may be used alone or in combination of two or more. A typical melamine compound is monoalkylated melamine-formaldehyde resin.

[0072] When the polymer layer-forming material contains an amino-based crosslinking agent, it is also preferable to further use a carboxylic acid compound, a phosphoric acid compound, a sulfonic acid compound, or the like as a curing catalyst.

[0073] (Silane coupling agent) The silane coupling agent is not particularly limited and can be selected from conventionally known agents, such as epoxy-based alkoxysilanes, amino-based alkoxysilanes, and isocyanate-based alkoxysilanes. These may be used alone or in combination of two or more.

[0074] The content of the crosslinking agent is preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, and even more preferably 1 to 25% by mass, based on the total solid content of the polymer layer-forming material. When the content of the crosslinking agent is within the above range, crosslinking can be performed while maintaining the flexibility of the polymer layer, thereby enabling the polymer layer to exhibit good adhesion to the aluminum layer. Furthermore, the laminate may be aged depending on the type and amount of the resin and crosslinking agent that constitute the polymer layer, so that the crosslinking agent can react sufficiently.

[0075] <Coloring agent> When the first polymer layer and the second polymer layer are inks or varnishes, the polymer layers preferably further contain a colorant from the viewpoint of resistance to basic aqueous solutions. The colorant is preferably a pigment, and examples of organic pigments include, but are not limited to, soluble azo pigments, insoluble azo pigments, azo pigments, phthalocyanine pigments, halogenated phthalocyanine pigments, anthraquinone pigments, anthanthrone pigments, dianthraquinonyl pigments, anthrapyrimidine pigments, perylene pigments, perinone pigments, quinacridone pigments, thioindigo pigments, dioxazine pigments, isoindolinone pigments, quinophthalone pigments, azomethine azo pigments, flavanthrone pigments, diketopyrrolopyrrole pigments, isoindoline pigments, indanthrone pigments, and carbon black pigments. Other suitable examples include carmine 6B, lake red C, permanent red 2B, disazo yellow, pyrazolone orange, carmine FB, cromophtal yellow, cromophtal red, phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone magenta, quinacridone red, indanthrone blue, pyrimidine yellow, thioindigo bordeaux, thioindigo magenta, perylene red, perinone orange, isoindolinone yellow, aniline black, diketopyrrolopyrrole red, and daylight fluorescent pigments. CI pigments listed in the Color Index can also be used as the colorant.

[0076] Examples of inorganic pigments include white inorganic pigments such as titanium oxide, silica, zinc oxide, zinc sulfide, and chromium oxide. Among inorganic pigments, titanium oxide is preferred. Titanium oxide exhibits a white color and is preferred in terms of coloring power, hiding power, chemical resistance, and weather resistance. From the viewpoint of printing performance, titanium oxide that has been treated with silica and / or alumina is preferred.

[0077] The first polymer layer and the second polymer layer are preferably subjected to a baking process after lamination. The baking process improves the adhesive strength between the aluminum foil and the polymer layer, making it easier to suppress dissolution of the aluminum layer in a basic aqueous solution. The heating temperature in the baking process is preferably 50°C to 350°C, more preferably 100°C to 250°C, as the surface temperature of the aluminum foil. The heating method in the baking process is not particularly limited, and may be an oven, a metal roll, or heating with molten resin during extrusion lamination.

[0078] <Aluminum foil> The aluminum foil in the embodiment of the present invention is a metallic luster layer having a metallic aluminum film, and preferably, a hard or soft aluminum foil having a thickness of 5 μm or more can be used, and the thickness is more preferably 7 μm or more from the viewpoint of recycling efficiency, and further preferably 10 to 30 μm. The aluminum foil may contain a small amount of metal elements other than aluminum, and examples of such metal elements include iron, silicon, copper, etc. As the aluminum foil, a known aluminum foil can be used. In addition, the aluminum foil generally has one side called a glossy surface and the other side called a matte surface (also simply called a matte surface), and the two surfaces have different glosses. In such a case, the polymer layer is located on both the glossy surface and the matte surface.

[0079] <Method of manufacturing recycled aluminum> The method for producing recovered aluminum of the present invention includes a separation step of contacting the laminate of the present invention with a basic aqueous solution to peel off the release layer from at least one plastic substrate layer to obtain an aluminum foil-containing laminate including a separation layer, and an aluminum recovery step of obtaining recovered aluminum from the aluminum foil-containing laminate. The aluminum foil-containing laminate can be preferably melted and regenerated to recycle the aluminum. From the viewpoint of improving the recycling yield, it is preferable that the unpeeled laminate contains as little plastic substrate as possible.

[0080] <Separation process> The separation step is a step in which the laminate of the present invention is brought into contact with a basic aqueous solution to peel the release layer from at least one plastic substrate layer, thereby obtaining an aluminum foil-containing laminate including a separation layer.

[0081] (basic aqueous solution) The basic aqueous solution is prepared by dissolving a basic compound in water. The basic compound may be any compound that swells and / or dissolves the release layer, and examples thereof include metal hydroxides such as sodium hydroxide and amine compounds such as ammonia. Among these, metal hydroxides are preferred because they are strongly alkaline in small amounts and provide good release performance, and sodium hydroxide, which has high solubility in water, is particularly preferred. The concentration of the basic compound can be adjusted appropriately depending on the basicity and solubility of the type of basic compound and the temperature. For example, in the case of a sodium hydroxide aqueous solution at 50°C, the concentration is preferably 0.1% to 10.0%, more preferably 0.5% to 5.0%. A low concentration of the basic compound reduces release performance, while a high concentration facilitates dissolution of the aluminum foil.

[0082] In the separation step, the temperature of the basic aqueous solution is preferably 20°C or higher and 80°C or lower, more preferably 30°C or higher and 70°C or lower. If the temperature is 70°C or higher, the aluminum foil is dissolved or corroded by the basic aqueous solution, and the recovery rate of the aluminum foil tends to decrease. If the temperature is lower than 20°C, the release layer is not sufficiently dissolved or swollen by the basic aqueous solution, and the release performance tends to decrease, making it difficult to separate the plastic substrate and the aluminum foil, and the recovery rate tends to decrease.

[0083] In the separation step, the contact time of the laminate with the basic aqueous solution is preferably 1 minute to 24 hours, more preferably 1 minute to 12 hours, and more preferably 1 minute to 6 hours. When the laminate is contacted with the basic aqueous solution, stirring or circulation is preferably performed to improve the peeling efficiency of the release layer. In this case, the rotation speed is preferably 80 to 5000 rpm, more preferably 80 to 4000 rpm.

[0084] The basic aqueous solution may further contain a surfactant to improve peeling performance. The surfactant is preferably an anionic surfactant and / or a nonionic surfactant. Examples of anionic surfactants include alkyl ether carboxylates and alkylbenzene sulfonates, and examples of nonionic surfactants include polyoxyethylene alkyl ethers. Known surfactants can be used.

[0085] The content of the laminate when contacting it with the basic aqueous solution is preferably 0.1% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 8% by mass or less, even more preferably 1.5% by mass or more and 7% by mass or less, and even more preferably 2% by mass or more and 6% by mass or less, based on the total mass of the basic aqueous solution. A content of 0.1% by mass or more is preferred from the viewpoint of treatment efficiency. A content of 10% by mass or less is preferred from the viewpoint of peeling performance.

[0086] (Cutting and crushing) In the method for producing recovered aluminum of the present invention, it is preferable to cut or crush the laminate before the separation step. In the embodiment of the present invention, "cutting" refers to adjusting the laminate to a desired size. Cutting can be performed by a known method, and scissors or a utility knife can be used for small amounts, and a known plastic cutter or crusher can be used for large amounts. The basic aqueous solution penetrates from the edge portion of the laminate, contacts the release layer, and dissolves or swells it, thereby separating the plastic substrate and the separation layer. Therefore, in order to efficiently proceed with the peeling process, it is preferable that the laminate is cut or crushed and immersed in the basic aqueous solution so that the release layer is exposed on the cross section. The cut size of the laminate is preferably 0.1 cm 2 ~25cm 2 , and more preferably 0.5 cm 2 ~10cm 2 When the cut size of the laminate is within the above range, the contact area between the basic aqueous solution and the aluminum foil is not too large, so excessive dissolution of aluminum is suppressed, and the recovery rate of aluminum is further improved. At the same time, cutting to an appropriate size allows the basic aqueous solution to effectively contact and penetrate into the release layer, so the peeling efficiency is further improved and the recovery rate of the laminate and the efficiency of cutting can be ensured.

[0087] <Aluminum recovery process> In the aluminum recovery step, the first polymer layer and the second polymer layer are removed from the aluminum foil-containing laminate. The polymer layers can be removed, for example, by the washing step and the heat-melting step described below. (Washing step) A step of washing the recovered aluminum foil-containing laminate with water. (Heat melting process) A process in which the first polymer layer, the second polymer layer, and other plastics are heated and burned from the aluminum foil-containing laminate obtained in the washing process, and then the aluminum is melted and separated to obtain recycled aluminum ingots.

[0088] The washing step is carried out to remove basic aqueous solution components such as basic compounds and surfactants that have adhered to the aluminum foil-containing laminate that has been separated and recovered from the plastic substrate. The heat-melting step can be carried out by a known method such as that shown in Japanese Patent Application Laid-Open No. 11-92838. Because the recycled aluminum base metal is recycled with the plastic substrate peeled off, it is made of aluminum with a higher purity than the laminate before the separation step, and can be used in a variety of fields such as daily necessities and machine parts by casting.

[0089] Furthermore, when the first polymer layer and the second polymer layer are made of materials having an acid value, instead of the heat-melting step, the polymer layers can be peeled off by contacting the aluminum foil-containing laminate with a basic aqueous solution under conditions harsher than those for peeling the release layer. Contact under harsh conditions includes contact for a longer period of time, contact at a higher temperature, contact under stirring at a higher rotation speed, etc. The contact is carried out within a range that can achieve the object of the present invention.

[0090] Since the present invention aims to recover and recycle aluminum, an embodiment in which as much aluminum as possible is separated and recovered from the laminate is preferred. Specifically, it is preferable that 50% by mass or more of the theoretical mass of aluminum contained in the laminate is recovered relative to 100% of the laminate. More preferably, 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 90% by mass or more is recovered.

[0091] In the method for producing recovered aluminum of the present invention, it is preferable to further separate and recover plastic substrates to obtain recovered plastic substrates. The recovered plastic substrates are preferably obtained simultaneously with or after the separation step. The method for separating and recovering the plastic substrate is not particularly limited, and examples thereof include known methods such as optical sorting, gravity sorting, and size sorting. In the present invention, gravity sorting is preferably used because it is possible and simple to separate the plastic substrate and aluminum by utilizing the difference in specific gravity between them. The gravity sorting is preferably performed after the peeling of the release layer in the separation step. The recovered plastic substrate is preferably recyclable by melting after recovery, and therefore preferably contains a small amount of the first polymer layer, the second polymer layer, and the aluminum foil contained in the unpeeled laminate, as well as the aluminum foil dissolved and pulverized by a basic aqueous solution, so that the plastic substrate can be regenerated into a colorless, transparent plastic that is free from coloration and obscuration during melting and recycling. In the separation and recovery of the plastic substrates, it is preferable that 50% by mass or more of the plastic substrates contained in the laminate are recovered relative to 100% of the laminate, more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 90% by mass or more.

[0092] The recovered plastic substrate can be melt-kneaded, for example, in the following steps to produce a molding material. (Plastic washing process) A process in which the recovered plastic substrates are washed with water. (Melting and kneading process) The plastic base material obtained in the plastic washing process is melted and kneaded to obtain recycled resin. (Masterbatch mixing process) A process in which the masterbatch is mixed with the recycled resin obtained in the melt-kneading process.

[0093] The plastic washing process is performed to remove basic aqueous solution components, such as basic compounds and surfactants, adhering to the recovered plastic substrate. The melt-kneading process involves adding various additives as needed, mixing using a Henschel mixer, tumbler, disperser, or the like, and then mixing and dispersing using a batch mixer such as a kneader, roll mill, super mixer, Henschel mixer, Schuggie mixer, vertical granulator, high-speed mixer, Farmatrix, ball mill, steel mill, sand mill, vibration mill, attritor, or Banbury mixer, a twin-screw extruder, a single-screw extruder, or a rotor-type twin-screw kneader. This results in a recycled resin, which is a resin composition. The shape of the recycled resin is not particularly limited and may be in the form of pellets, powder, granules, or beads. A twin-screw extruder is preferably used for the melt-kneading process.

[0094] (Masterbatch mixing process) The recycled resin derived from the recovered plastic substrate can be further mixed with a masterbatch to form a molding material. The masterbatch is not particularly limited as long as it is compatible with the recycled resin, and generally, a mixture of a thermoplastic resin such as a polyethylene resin or a polypropylene resin and a colorant can be used. The thermoplastic resin contained in the masterbatch may be used alone or in combination of two or more types. The molding material may contain, within the scope that does not impair the effects of the present invention, metal soap of an alkali metal, alkaline earth metal, or zinc, hydrotalcite, nonionic surfactant, cationic surfactant, anionic surfactant, amphoteric surfactant, antistatic agent, flame retardant such as a halogen-based, phosphorus-based, or metal oxide, lubricant such as ethylene bisalkylamide, antioxidant, ultraviolet absorber, or filler.

[0095] <Method of manufacturing molded body> The molding material obtained by the above-described production method can be heated and molded to obtain a molded article. The heating and molding method is not particularly limited, and examples thereof include injection molding, extrusion molding, blow molding, and compression molding. Molding materials produced using plastic substrates recovered according to particularly preferred embodiments of the present invention are of high quality because the printing layer and adhesive layer have been detached and further because reattachment of the detached components is suppressed, and can be used in a variety of fields, including home appliances, stationery, automobile parts, toys, sporting goods, medical use, and building or construction materials. [Example]

[0096] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the examples, parts and % represent parts by mass and % by mass unless otherwise noted.

[0097] <Molecular weight and molecular weight distribution> The weight average molecular weight (Mw), number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) were measured by GPC (gel permeation chromatography) and calculated as molecular weights converted using polystyrene as a standard substance. The measurement conditions are shown below. GPC equipment: Showa Denko Shodex GPC-104 Columns: The following columns were used in series. Showa Denko Shodex LF-404 (2 pieces) Showa Denko Shodex LF-G Detector: RI (differential refractometer) Measurement conditions: Column temperature 40°C Eluent: tetrahydrofuran Flow rate: 0.3mL / min

[0098] <Acid value, hydroxyl value> The acid value and hydroxyl value were measured according to the method described in JIS K 0070 (1992).

[0099] <Production of materials for forming the peelable polymer layer, the first polymer layer, and the second polymer layer> [Synthesis Example 1-1] (Polyurethane Resin P1) In a reactor equipped with a reflux condenser, a dropping funnel, a gas inlet pipe, a stirrer, and a thermometer, 152.2 parts of PPA (a polyester polyol composed of a polycondensate of propylene glycol and adipic acid and having a number average molecular weight of 2,000), 15.2 parts of PPG (a polyether polyol composed of polypropylene glycol and having a number average molecular weight of 2,000), 13.6 parts of BD (1,4-butanediol), 99.8 parts of IPDI (isophorone diisocyanate), and 200 parts of NPAC (normal propyl acetate) were charged while introducing nitrogen gas, and the mixture was allowed to react at 90°C for 5 hours to obtain a urethane prepolymer solution having isocyanate groups at its terminals. Next, a mixture of 19.2 parts of AEA (2-(2-aminoethylamino)ethanol) and 350 parts of IPA (isopropyl alcohol) was added dropwise at room temperature over 60 minutes, and then the mixture was allowed to react at 70°C for 3 hours to obtain a polyurethane resin solution. NPAC was added to the resulting polyurethane resin solution to adjust the solid content, yielding a solution of polyurethane resin P1 with a solid content concentration of 30%, a weight average molecular weight of 27,000, Mw / Mn=3.1, and an acid value of 0.0 mgKOH / g.

[0100] [Synthesis Example 1-2] (Polyurethane Resin P2) In a reactor equipped with a reflux condenser, a dropping funnel, a gas inlet tube, a stirrer, and a thermometer, 135.7 parts of PPA, 13.6 parts of PPG, 28.3 parts of DMPA (2,2-dimethylolpropanoic acid), 105.7 parts of IPDI, and 200 parts of NPAC were charged while introducing nitrogen gas, and the mixture was reacted at 90°C for 5 hours to obtain a urethane prepolymer solution having an isocyanate group at its terminal. Next, a mixture of 16.7 parts of AEA and 350 parts of IPA was added dropwise at room temperature over 60 minutes, and then the mixture was allowed to react at 70° C. for 3 hours to obtain a polyurethane resin solution. NPAC was added to the resulting polyurethane resin solution to adjust the solid content, yielding a solution of polyurethane resin P2 with a solid content concentration of 30%, a weight average molecular weight of 30,000, Mw / Mn=3.0, and an acid value of 39.3 mgKOH / g.

[0101] [Preparation of Resins for Peelable Polymer Layer, First Polymer Layer, and Second Polymer Layer] The materials were stirred and mixed using a disperser in the blending ratios shown in Table 1 to prepare resin varnishes P3 to P6.

[0102] [Table 1]

[0103] The details of the materials in Table 1 are as follows: NC DHX 8-13: Nobel NC Company, acid value <0.1 Solbin M5: Nissin Chemical Industry Co., Ltd., acid value 5.8 JER1007: Mitsubishi Chemical Corporation, acid value <0.1 Byron 200: Toyobo MC Co., Ltd., acid value 1.0 MEK: Methyl ethyl ketone

[0104] [Preparation of Varnishes H1 to H3 for Peelable Polymer Layers] The materials were mixed and stirred using a disperser in the blending ratios shown in Table 2 to prepare varnishes H1 to H3 for the peelable polymer layer.

[0105] [Table 2]

[0106] [Preparation of Varnishes R1 to R5 for the First Polymer Layer and the Second Polymer Layer] The materials were mixed and stirred using a disperser in the blending ratios shown in Table 3 to prepare varnishes R1 to R5.

[0107] [Table 3]

[0108] Details of the materials in Tables 2 and 3 are as follows: Duranate D-101: Asahi Kasei Corporation, acid value <0.1, solids content 100% KBM-403: Shin-Etsu Chemical Co., Ltd., acid value <0.1, solids 100% CYMEL325: ALLNEX, acid value <0.1, solids content 80%

[0109] [Preparation of Inks I1 to I4 for First Polymer Layer and Second Polymer Layer] (Preparation of Ink I1) 20 parts of Resin Varnish P3, 30 parts of titanium dioxide (Tipake PF736: Ishihara Sangyo Kaisha), 10 parts of ethyl acetate, and 10 parts of IPA were mixed and stirred, and dispersed for 20 minutes using a sand mill. Then, 10 parts of Ink Resin Varnish P2, 10 parts of ethyl acetate, 8.5 parts of IPA, and 1.5 parts of Coronate 2785 were mixed and stirred to obtain Ink I1.

[0110] (Preparation of Inks I2 to I4) Inks I2 to I4 were prepared in the same manner as ink I1, except that the blending ratios were changed to those shown in Table 4.

[0111] [Table 4]

[0112] The details of the materials in Table 4 are as follows: LIONOL YELLOW 1805-G:P.Y83 Toyocolor

[0113] [Synthesis Example 2-1] (Polyester polyol B1) A reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping tank, and nitrogen gas inlet tube was charged with 124 parts of ethylene glycol, 212 parts of neopentyl glycol, 368 parts of 1,6-hexanediol, 645 parts of isophthalic acid, 36 parts of adipic acid, and 265 parts of sebacic acid. The mixture was heated to 250°C with stirring under a nitrogen stream to carry out an esterification reaction. The reaction was continued until a predetermined amount of water was distilled and the acid value reached 5 or less. The pressure was then gradually reduced, and the deglycolization reaction was carried out at 1 mmHg or less for 5 hours to obtain a polyester polyol. Subsequently, 35 parts of isophorone diisocyanate was gradually added, and the reaction was carried out at 150°C for approximately 2 hours to obtain a polyester polyurethane polyol. 12.0 parts of ethylene glycol bis-anhydrotrimellitate was added to 100 parts of this polyester polyurethane polyol, and the mixture was allowed to react at 180°C for approximately 2 hours. The mixture was then diluted with ethyl acetate to a solids concentration of 50%, yielding a solution of partially acid-modified polyester polyol B1 with a number average molecular weight of 9,000 and an acid value of 30.3 mgKOH / g.

[0114] [Synthesis Example 2-2] (Polyester polyol B2) A reactor equipped with a stirrer, thermometer, reflux condenser, dropping tank, and nitrogen gas inlet tube was charged with 263 parts of ethylene glycol, 937 parts of neopentyl glycol, 472 parts of isophthalic acid, and 528 parts of adipic acid. The mixture was heated to 250 ° C. with stirring under a nitrogen stream to carry out an esterification reaction. After a predetermined amount of water was distilled and the reaction was continued until the acid value reached 5 or less, the pressure was gradually reduced and the deglycolization reaction was carried out at 1 mmHg or less for 5 hours to obtain a polyester polyol. The mixture was then diluted with ethyl acetate to a solids concentration of 50%, yielding a polyester polyol solution B2 with a number average molecular weight of 2,700 and an acid value of 0.5 mgKOH / g.

[0115] <Preparation of polyisocyanate solution> [Preparation Example 1] (Polyisocyanate C1) Coronate 2785 (biuret type polyisocyanate derived from hexamethylene diisocyanate, manufactured by Tosoh Corporation) was diluted with ethyl acetate to adjust the solid concentration to 50% and NCO%=9.6%, to obtain a solution of polyisocyanate C1.

[0116] <Adhesive manufacturing> [Manufacturing Example 2-1] (Adhesive D1) 100 parts of the polyester polyol B1 solution and 8 parts of the polyisocyanate C1 solution were mixed, and ethyl acetate was added to prepare an adhesive solution D1 with a solids concentration of 30% and an acid value of 28.1. [Manufacturing Example 2-2] (Adhesive D2) 100 parts of the polyester polyol B2 solution and 30 parts of the polyisocyanate C1 solution were mixed, and ethyl acetate was added to prepare adhesive solution D2 with a solids concentration of 30% and an acid value of 0.4. [Manufacturing Example 2-3] (Adhesive D3) 100 parts of Unistall P-401 (Mitsui Chemicals) and 2 parts of polyisocyanate C1 solution were mixed, and toluene was added to prepare adhesive solution D3 with a solids concentration of 7% and an acid value of 50.

[0117] <Production of laminate> The method for producing the laminate will be described below: The ink and varnish were diluted with MEK to a viscosity of 14 to 18 seconds (25°C, Zahn cup #3 (manufactured by Rigo Co., Ltd.) before use.

[0118] [Example 1] (Laminate L1) Diluted varnish H1 was printed onto OPP (biaxially oriented polypropylene, thickness 20 μm) using a gravure printing machine equipped with a gravure plate with a plate depth of 30 μm so that the thickness after drying would be 1 μm, and the print was dried at 70°C to obtain a laminate consisting of a base layer (OPP) / varnish layer (H1). Next, the diluted varnish R1 was printed onto the matte surface of an aluminum foil (manufactured by Toyo Aluminum, thickness 20 μm) using a gravure printing machine equipped with a gravure plate with a plate depth of 30 μm so that the thickness after drying would be 1 μm, and the print was baked at 250°C to obtain a laminate consisting of aluminum foil / varnish layer (R1). Next, adhesive D2 was applied to a thickness of 3 μm on the varnish layer of the resulting laminate having a base layer (OPP) / varnish layer (H1) structure using a dry laminator and dried, and then laminated with aluminum foil / varnish layer (R1) to obtain laminate L1 having a structure of base layer (OPP) / varnish layer (H1) / adhesive layer (D2) / aluminum foil / varnish layer (R1).

[0119] [Examples 2 to 4] (Laminates L2 to L4) Except for changing the materials shown in Table 5, the same method as in the production of the laminate L1 was used to obtain laminates L2 to L4.

[0120] [Example 5] (Laminate L5) The diluted ink I1 was printed on the matte surface of an aluminum foil (manufactured by Toyo Aluminum Co., Ltd., thickness 20 μm) using a gravure printing machine equipped with a gravure plate with a plate depth of 30 μm so that the thickness after drying would be 1 μm, and the print was baked at 250°C to obtain a laminate consisting of aluminum foil / ink layer (I1). Subsequently, ink I1 was printed in the same manner on the glossy side of the aluminum foil of the above laminate to obtain a laminate having a structure of ink layer (I1) / aluminum foil / ink layer (I1). Next, adhesive D1 was applied to OPP (thickness 20 μm) using a dry laminator to a thickness of 3 μm and dried, and then it was bonded to a laminate having a configuration of ink layer (I1) / aluminum foil / ink layer (I1) to obtain laminate L5 having a configuration of base layer (OPP) / adhesive layer (D1) / ink layer (I1) / aluminum foil / ink layer (I1).

[0121] [Examples 6 to 11] (Laminates L6 to L11) Laminates L6 to L11 were obtained in the same manner as in the production of laminate L5, except that the materials were changed as shown in Table 5. In Example 11, PET was used as a substrate having a thickness of 12 μm.

[0122] [Example 12] (Laminate L12) Diluted varnish H1 was printed onto OPP (thickness 20 μm) using a gravure printing machine equipped with a gravure plate with a plate depth of 30 μm so that the thickness after drying would be 1 μm, and the print was dried at 70°C to obtain a laminate consisting of a base layer (OPP) / varnish layer (H1). Next, adhesive D2 was applied to the varnish layer of the obtained base layer (OPP) / varnish layer (H1) laminate using a dry laminator to a thickness of 3 μm and dried, and then it was bonded to the glossy side of aluminum foil (manufactured by Toyo Aluminum, thickness 7 μm) to obtain a laminate consisting of base layer (OPP) / varnish layer (H1) / adhesive layer (D2) / aluminum foil. Ink I1 was then printed on the matte surface of the aluminum foil of the laminate to a thickness of 1 μm after drying. Adhesive D1 was then applied to Ink I1 using a dry laminator to a thickness of 3 μm and dried, after which it was laminated to CPP (unstretched polypropylene, 30 μm thick) to obtain laminate L12 having a structure of base layer (OPP) / varnish layer (H1) / adhesive layer (D2) / aluminum foil / ink (I1) / adhesive layer (D1) / CPP.

[0123] [Examples 13 to 15] (Laminates L13 to L15) Laminates L13 to L15 were obtained in the same manner as laminate L12, except that the materials were changed as shown in Table 5. In producing laminate L15, ink I1 was not printed, adhesive D2 was used instead of adhesive D1, and aluminum-deposited CPP (thickness 25 μm) was used instead of CPP.

[0124] [Example 16] (Laminate L16) Adhesive D1 was applied to OPP (thickness 20 μm) using a gravure printing machine to a thickness of 0.3 μm and dried, and then LDPE (low-density polyethylene) was extrusion-laminated to a thickness of 10 μm at 310°C using an extrusion laminator, thereby laminating it with the glossy side of aluminum foil (manufactured by Toyo Aluminum K.K., thickness 7 μm), to obtain a laminate consisting of base layer (OPP) / adhesive layer (D1) / LDPE / aluminum foil. Next, ink I1 was printed on the matte surface of the aluminum foil of the above laminate using a gravure printing machine so that the thickness after drying would be 1 μm, and then adhesive D1 was applied to a thickness of 0.3 μm and dried.After that, LDPE was extrusion laminated to a thickness of 15 μm at 310°C using an extrusion laminator, thereby obtaining a laminate L16 having a configuration of base layer (OPP) / adhesive layer (D1) / LDPE / aluminum foil / ink (I1) / adhesive layer (D1) / LDPE.

[0125] [Example 17] (Laminate L17) The diluted ink I1 was printed on the matte surface of an aluminum foil (manufactured by Toyo Aluminum Co., Ltd., thickness 20 μm) using a gravure printing machine equipped with a gravure plate with a plate depth of 30 μm so that the thickness after drying would be 1 μm, and the print was baked at 250°C to obtain a laminate consisting of aluminum foil / ink layer (I1). Next, ink I4 was similarly printed on the glossy side of the aluminum foil of the above laminate so that the thickness after drying would be 1 μm, thereby obtaining a laminate having a structure of ink layer (I4) / aluminum foil / ink layer (I1). Next, adhesive D1 was applied to the ink layer (I1) of the above laminate using a dry laminator to a thickness of 3 μm and dried, and then it was laminated with CPP (thickness 30 μm) to obtain laminate L17 having a structure of ink layer (I4) / aluminum foil / ink layer (I1) / adhesive layer (D1) / LDPE.

[0126] [Example 18] (Laminate L18) Laminate L18 was obtained in the same manner as laminate L17, except that adhesive D2 was used instead of adhesive D1 and aluminum-deposited CPP (thickness 25 μm) was used instead of CPP, so as to have the configuration shown in Table 5.

[0127] [Example 19] (Laminate L19) Diluted varnish R3 was printed onto the matte surface of aluminum foil (manufactured by Toyo Aluminum, thickness 20 μm) using a gravure printing machine equipped with a gravure plate with a plate depth of 30 μm so that the thickness after drying would be 1 μm, and the print was baked at 250°C to obtain a laminate consisting of aluminum foil / varnish layer (R3). Next, ink I1 was similarly printed on the glossy side of the aluminum foil of the above laminate so that the thickness after drying would be 1 μm, thereby obtaining a laminate having a configuration of ink layer (I1) / aluminum foil / varnish layer (R3). Next, adhesive D3 was applied to the ink layer (I1) of the above laminate to a thickness of 5 μm and baked at 250°C to obtain a laminate having a structure of adhesive layer (D3) / ink layer (I1) / aluminum foil / varnish layer (R3). Furthermore, the adhesive layer (D3) of the above laminate was pressed against a CPP (thickness 300 μm) at 200°C for 0.5 seconds to obtain a laminate L19 having a structure of base layer (CPP) / adhesive layer (D3) / ink layer (I1) / aluminum foil / varnish layer (R3).

[0128] <Production of Comparative Laminates LL1 to LL5> The method for producing the comparative laminate will be explained below with reference to Table 6.

[0129] [Comparative Example 1] (Comparative laminate LL1) Adhesive D1 was applied to OPP (thickness 20 μm) using a dry laminator to a thickness of 3 μm and dried, and then laminated with aluminum foil (thickness 20 μm) to obtain a comparative laminate LL1 having a structure of base layer (OPP) / adhesive layer (D1) / aluminum foil.

[0130] [Comparative Example 2] (Comparative laminate LL2) The diluted ink I1 was printed on the glossy side of an aluminum foil (thickness 20 μm) using a gravure printing machine equipped with a gravure plate with a plate depth of 30 μm so that the thickness after drying would be 1 μm, and the print was baked at 250°C to obtain a laminate consisting of an ink layer (I1) / aluminum foil. Next, adhesive D1 was applied to a thickness of 3 μmg / m on OPP (thickness 20 μm) using a dry laminating machine. 2After applying and drying the ink layer (I1) so that the ink layer (I1) was in the above laminate having a structure of ink layer (I1) / aluminum foil, the ink layer (I1) was adhered to the ink layer (I1) of the above laminate having a structure of ink layer (I1) / aluminum foil to obtain a comparative laminate LL2 having a structure of base layer (OPP) / adhesive layer (D1) / ink layer (I1) / aluminum foil.

[0131] [Comparative Example 3] (Comparative laminate LL3) The diluted ink I1 was printed onto the matte surface of an aluminum foil (thickness 20 μm) using a gravure printing machine equipped with a gravure plate with a plate depth of 30 μm so that the thickness after drying would be 1 μm, and the print was baked at 250°C to obtain a laminate consisting of aluminum foil / ink (I1). Next, adhesive D1 was applied to OPP (thickness 20 μm) using a dry laminator to a thickness of 3 μm and dried, and then this was bonded to the glossy side of the aluminum foil of the above laminate having a structure of aluminum foil / ink layer (I1) to obtain a comparative laminate LL3 having a structure of base layer (OPP) / adhesive layer (D1) / aluminum foil / ink layer (I1).

[0132] [Comparative Example 4] (Comparative laminate LL4) The diluted ink I1 was printed onto the matte surface of an aluminum foil (thickness 20 μm) using a gravure printing machine equipped with a gravure plate with a plate depth of 30 μm so that the thickness after drying would be 1 μm, and the print was baked at 250°C to obtain a laminate consisting of aluminum foil / ink (I1). Next, adhesive D2 was applied to OPP (thickness 20 μm) using a dry laminator to a thickness of 3 μm and dried, and then it was bonded to the glossy aluminum foil side of the aluminum foil / ink layer (I1) laminate to obtain a comparative laminate LL4 having a structure of base layer (OPP) / adhesive layer (D2) / aluminum foil / ink layer (I1).

[0133] [Comparative Example 5] (Comparative laminate LL5) Adhesive D2 was applied to OPP (thickness 20 μm) using a dry laminator to a thickness of 3 μm and dried, and then the adhesive was attached to the glossy side of aluminum foil (thickness 7 μm) to obtain a laminate consisting of base layer (OPP) / adhesive layer (D2) / aluminum foil. Furthermore, adhesive D2 was applied to the matte surface of the aluminum foil of the above laminate using a dry laminator to a thickness of 3 μm and dried, and then CPP (thickness 30 μm) was attached to obtain a comparative laminate LL5 having a structure of base layer (OPP) / adhesive layer (D2) / aluminum foil / adhesive layer (D2) / CPP.

[0134] [Table 5]

[0135] [Table 6]

[0136] [Examples 20 to 41, Comparative Examples 1 to 5] <Production of recycled aluminum> Using the laminates produced in the above Examples and Comparative Examples, recovered aluminum was produced in the following manner. 50 g of the laminate was cut into 1 cm × 1 cm pieces and added to 2000 g of a basic aqueous solution having the composition shown in Tables 7 and 8, followed by stirring at 50°C for 3 hours. After cooling, the mixture was allowed to stand for separation, and the floating matter was removed from the upper part of the liquid. The sediment containing the aluminum-containing laminate was then recovered by filtration to obtain the aluminum-containing laminate (separation step). After the settling separation, if the plastic substrate was floating, the plastic substrate was recovered from the upper part of the liquid. If the plastic substrate had settled, the floating matter was removed from the upper part of the liquid, and then the sediment containing the plastic substrate was recovered by filtration to obtain a recovered plastic substrate. In Example 33, after all the sediment was recovered, the settling separation was similarly carried out in a heavy liquid of sodium polytungstate adjusted to a specific gravity of 2.0, and the plastic substrate and sediment were recovered. The aluminum-containing laminate was washed with water to remove the basic aqueous solution, then dried, and heated at 600 ° C in an electric furnace with N gas introduced to obtain recovered aluminum ingot.

[0137] The activators used in the basic aqueous solutions in Examples 30 to 41 are as follows: Nonionic surfactant: Polyoxyethylene (POE) lauryl ether, POE addition number: 4, solid content: 100% Anionic surfactant: POE lauryl ether phosphate, POE addition number: 4, solid content: 100% Cationic surfactant: Lauryltrimethylammonium chloride, solid content 27%

[0138] <Evaluation> The following evaluations were carried out for Examples 20 to 41 and Comparative Examples 1 to 5. The results are shown in Tables 7 and 8.

[0139] (peelability) The laminate was cut into 1 cm x 1 cm pieces and immersed in a 1% by mass aqueous solution of sodium hydroxide at 60°C for 6 hours. The peeling of the release layer was visually evaluated to determine whether the plastic substrate and the aluminum-containing laminate including the separation layer had separated (good) or not (bad).

[0140] (Plastic recovery rate) The plastic substrates recovered in Examples 20 to 41 and Comparative Examples 1 to 5 were washed with water and then dried. The mass of the recovered plastic substrate was measured and compared with the mass of the plastic substrate in the laminate before the peeling treatment to calculate the recovery rate. [Evaluation criteria] A (Excellent): Recovery rate is 90% or more B (Good): Recovery rate is less than 90% and more than 70% C (Acceptable): Recovery rate is less than 70% and more than 50% D (Not acceptable): Recovery rate is less than 50% or separation and recovery is not possible

[0141] (aluminum recovery rate) The aluminum-containing laminates recovered in Examples 20 to 41 and Comparative Examples 1 to 5 were washed with water and dried, and the mass and inorganic matter ratio of the recovered aluminum-containing laminates were measured, and the aluminum recovery rate was calculated using the following formula: The inorganic matter ratio was determined as the residual fraction when heated to 600°C in a N2 atmosphere using a Shimadzu DTG-60 by thermogravimetric analysis according to JIS K 7120.

[0142] Calculation formula

number

[0143] [Evaluation criteria] A (Excellent): Recovery rate is 90% or more B (Good): Recovery rate is less than 90% and more than 70% C (Acceptable): Recovery rate is less than 70% and more than 50% D (Not acceptable): Recovery rate is less than 50% or separation and recovery is not possible

[0144] (Coloring of recycled film) The plastic substrates recovered in Examples 20 to 41 and Comparative Examples 1 to 5 were pelletized at a melting temperature of 200°C for OPP or CPP, or 290°C for PET, to obtain recycled resin pellets. The pellets were extruded using a T-die film molding machine at 200°C for OPP or CPP, or 290°C for PET, to produce recycled films with a thickness of 100 μm. Regarding the coloration of the recycled film, the total light transmittance was measured using a haze meter (SH7000, manufactured by Nippon Denshi Kogyo Co., Ltd.) and evaluated according to the following criteria. [Evaluation criteria] A (Excellent): Total light transmittance is 90% or more B (Good): Total light transmittance is 80% or more but less than 90% C (Acceptable): Total light transmittance is 70% or more but less than 80% D (unacceptable): Total light transmittance is less than 70%

[0145] (Repeatability) In Examples 20 to 41 and Comparative Examples 1 to 5, after recovering the plastic substrate and aluminum-containing laminate, the laminate before the peeling treatment was again placed in the basic aqueous solution and subjected to the peeling treatment in the same manner. This was repeated five times, and the change in the plastic recovery rate was evaluated. [Evaluation criteria] A (Excellent): Change in recovery rate is less than 10% B (Good): The change in recovery rate is between 10% and 20%. C (Acceptable): The change in recovery rate is 20% or more but less than 30% D (unacceptable): The change in recovery rate is 30% or more.

[0146] [Table 7]

[0147] [Table 8]

[0148] The above evaluation results show that aluminum can be separated and recovered with a high yield by treating the laminate of the embodiment of the present invention with a basic aqueous solution. In a more preferred embodiment, the basic aqueous solution causes little deterioration, so the laminate can be repeatedly peeled off. In a more preferred embodiment, plastic substrates can be recovered with a high yield, and high-quality plastics with high transmittance can be recycled from the recovered plastic substrates.

Claims

1. A laminate having at least one plastic substrate, a release layer, and a separation layer in this order, the separating layer comprises a first polymer layer, an aluminum foil, and a second polymer layer in this order; the release layer is an inorganic substance vapor deposition layer and / or a releaseable polymer layer made of a material having an acid value higher than that of a material constituting the first polymer layer and higher than that of a material constituting the second polymer layer; When the laminate is cut into a piece of 1 cm x 1 cm and immersed in a 1% by mass aqueous solution of sodium hydroxide at 60°C for 6 hours, the peel layer peels off from the plastic substrate, thereby enabling the aluminum foil-containing laminate including the separation layer to be separated and recovered.

2. The laminate according to claim 1 , wherein the acid value of the material constituting the first polymer layer or the acid value of the material constituting the second polymer layer is less than 5 mg KOH / g.

3. 2. The laminate according to claim 1, wherein the acid value of the material constituting the first polymer layer and the acid value of the material constituting the second polymer layer are less than 5 mg KOH / g.

4. 4. The laminate according to claim 1, wherein at least one layer of the plastic substrate comprises a polyolefin resin.

5. 4. The laminate according to claim 1, wherein the first polymer layer and / or the second polymer layer comprises at least one resin selected from the group consisting of a vinyl chloride-vinyl acetate resin, a urethane resin, an epoxy resin, and a nitrocellulose resin.

6. The laminate according to any one of claims 1 to 3, wherein the first polymer layer and / or the second polymer layer has a structure derived from a crosslinking agent containing one or more selected from the group consisting of an isocyanate-based crosslinking agent, an amino-based crosslinking agent, and a silane coupling agent.

7. 4. The laminate according to claim 1, wherein the first polymer layer and / or the second polymer layer contains a colorant.

8. 4. The laminate according to claim 1, wherein the peelable polymer layer is a cured product of an adhesive containing a polyester polyol and a polyisocyanate.

9. The laminate according to any one of claims 1 to 3, wherein the aluminum foil has a thickness of 5 µm or more.

10. a separation step of contacting the laminate according to any one of claims 1 to 3 with a basic aqueous solution to peel the release layer from at least one plastic substrate layer to obtain an aluminum foil-containing laminate including a separation layer; A method for producing recovered aluminum, comprising an aluminum recovery step of obtaining recovered aluminum from the aluminum foil-containing laminate.

11. The method according to claim 10, wherein the amount of recovered aluminum relative to the amount of aluminum foil contained in the laminate before the separation step is 70 mass% or more.

12. The method according to claim 10, wherein the basic aqueous solution contains an anionic surfactant and / or a nonionic surfactant.

13. The method according to claim 10, further comprising separating and recovering the plastic substrate to obtain a recovered plastic substrate.

14. The method according to claim 13, wherein the amount of the recycled plastic substrate relative to the amount of the plastic substrate contained in the laminate before the separation step is 70% by mass or more.