Separation chemical solution and separation method

Abstract

Provided is a chemical for separation for separating at least one component from a mixed material or a composite material composed of two or more components including at least an ester bond-containing polymer component having an ester bond in a main chain structure, the chemical containing alcohol, a basic catalyst, and an auxiliary solvent.

Description

[Technical Field]

[0001] The present invention relates to a separation chemical solution for separating at least one component from a mixed material or composite material composed of two or more components, each containing at least an ester bond-containing polymer component having an ester bond in its main chain structure, and to a separation method using such a separation chemical solution. [Background technology]

[0002] From the perspective of protecting the global environment, methods are being considered for separating one or more components from various mixed and composite materials and making them recyclable.

[0003] For example, Patent Document 1 proposes a method for recovering polypropylene resin by dissolving the polyurethane resin in a resin composite formed from polyurethane resin and polypropylene resin using a treatment solution containing alcohols, ketones, or ethers. However, this technique in Patent Document 1 requires the treatment solution to be at a high temperature of around 145°C, which presents problems such as requiring a large amount of energy to achieve the high temperature and necessitating the use of large-scale equipment.

[0004] Furthermore, Patent Document 2 proposes a method for peeling a composite material by immersing it in a peeling solution containing a peeling agent and an aqueous solvent containing water in a ratio of more than 51% by weight and 100% by weight. However, in this method of Patent Document 2, since the peeling solution uses an aqueous solvent containing more than 51% by weight and 100% by weight of water, the swelling force necessary for penetration into the interfaces of each material constituting the composite material is insufficient, resulting in the problem that it takes a long time to peel or separate each material constituting the composite material. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2011-231277 [Patent Document 2] Special Publication No. 2023-530345 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The object of the present invention is to provide a separation solution that can suitably separate at least one component from a mixed material or composite material composed of two or more components, each containing at least an ester bond-containing polymer component having an ester bond in its main chain structure, under relatively mild conditions and in a relatively short time. [Means for solving the problem]

[0007] [1] According to one aspect of the present invention, a separation solution is provided for separating at least one component from a mixed material or composite material composed of two or more components, each containing at least an ester bond-containing polymer component having an ester bond in its main chain structure, the separation solution comprising an alcohol, a basic catalyst, and an auxiliary solvent.

[0008] [2]According to aspect 2 of the present invention, a separation chemical solution of aspect 1 is provided, wherein the mixed material or composite material is a laminate having a layer containing the ester bond-containing polymer component.

[0009] [3]According to aspect 3 of the present invention, a separation chemical solution of aspect 2 is provided, wherein the laminate is a packaging container.

[0010] [4]According to aspect 4 of the present invention, a separation chemical solution is provided which is any of aspects 1 to 3, wherein the auxiliary solvent is a dialkyl ketone, a halogenated alkane, or a cyclic ether.

[0011] [5]According to aspect 5 of the present invention, a separation chemical solution is provided which is any of aspects 1 to 4, wherein the auxiliary solvent is acetone.

[0012] [6] According to Aspect 6 of the present invention, there is provided a separation chemical solution according to any one of Aspects 1 to 5, wherein the content ratio of the alcohol to the auxiliary solvent is in the range of 10 / 90 to 90 / 10 in terms of the weight ratio of "alcohol / auxiliary solvent".

[0013] [7] According to Aspect 7 of the present invention, there is provided a separation chemical solution according to any one of Aspects 1 to 6, wherein the base catalyst is at least one selected from potassium carbonate, sodium hydroxide, potassium hydroxide, sodium alkoxide, and potassium alkoxide.

[0014] [8] According to Aspect 8 of the present invention, there is provided a separation chemical solution according to any one of Aspects 1 to 7, wherein the water content ratio is 10% by weight or less.

[0015] [9] According to Aspect 9 of the present invention, there is provided a separation method for separating at least one component from a mixed material or composite material composed of two or more components, which at least contains an ester bond-containing polymer component having an ester bond in the main chain structure, the method comprising the step of bringing the mixed material or composite material into contact with a separation chemical solution containing alcohol, a basic catalyst, and an auxiliary solvent.

[0016]

[10] According to Aspect 10 of the present invention, there is provided a separation method according to Aspect 9, wherein the mixed material or composite material is brought into contact with the separation chemical solution under temperature conditions of 0 to 65°C. [Advantages of the Invention]

[0017] According to the separation chemical solution of the present invention, at least one component can be preferably separated from a mixed material or composite material composed of two or more components, which at least contains an ester bond-containing polymer component having an ester bond in the main chain structure, under relatively mild conditions and in a relatively short time. [Brief Description of the Drawings]

[0018] [Figure 1] Figs. 1(A) to 1(C) are sample photos of Example 1.

Embodiments for Carrying Out the Invention

[0019] <Chemical Solution for Separation> The chemical solution for separation of the present invention contains alcohol, a basic catalyst, and a co-solvent. The chemical solution for separation of the present invention is used for separating at least one component from a mixed material or composite material composed of two or more components, which contains at least an ester bond-containing polymer component having an ester bond in the main chain structure.

[0020] According to the chemical solution for separation of the present invention, at least one component can be preferably separated from a mixed material or composite material composed of two or more components, which contains at least an ester bond-containing polymer component having an ester bond in the main chain structure (hereinafter, appropriately referred to as "ester bond-containing polymer component") under relatively mild conditions (preferably, temperature conditions of 0 to 65°C) and in a relatively short time.

[0021] Specifically, according to the chemical solution for separation of the present invention, it acts on the ester bond contained in the main chain structure of the ester bond-containing polymer component contained in the mixed material or composite material, whereby the ester bond-containing polymer component can be depolymerized under relatively mild conditions and in a relatively short time. And thereby, at least one component can be preferably separated from the mixed material or composite material. In particular, as a result of intensive studies by the present inventors, it has been found that a chemical solution for separation containing alcohol, a basic catalyst, and a co-solvent can cause the depolymerization of the ester bond-containing polymer component contained in the mixed material or composite material to proceed and be decomposed thereby under relatively mild conditions and in a relatively short time, and thus the present invention has been completed.

[0022] The mixed material or composite material used for separation by the separation chemical solution of the present invention is a mixed material or composite material composed of two or more components, wherein the components include at least an ester bond-containing polymer component having an ester bond in its main chain structure. It may be a mixed material formed by mixing two or more components, or a composite material formed by combining two or more components.

[0023] The mixed material comprising two or more components is not particularly limited, but may be a mixed material in which two or more components are uniformly mixed, or a mixed material in which at least one component is localized and distributed (for example, in the form of a polymer blend, alloy, or composite composed of two or more components). However, it is preferable that at least an ester bond-containing polymer component and components other than the ester bond-containing polymer component are mixed. For example, by contacting such a mixed material with the separation chemical solution of the present invention, the ester bond-containing polymer component contained in the mixed material can be depolymerized and decomposed, thereby separating components other than the ester bond-containing polymer component from the mixed material.

[0024] Furthermore, while the composite material is not particularly limited to two or more components, examples include materials in which two or more components are compounded in contact with each other, and even materials in which two or more components simply coexist. For example, laminates in which two or more components are stacked in layers, and fibers in which two or more fibers are blended are preferred examples. In particular, in the case of laminates, at least one layer L containing an ester bond-containing polymer component is preferred. E and layer L which does not contain ester bond-containing polymer components O A laminate having (i.e., a layer composed of components other than the ester bond-containing polymer component) is preferred. For example, by contacting such a laminate with the separation chemical solution of the present invention, the layer L containing the ester bond-containing polymer component is separated. EThe ester bond-containing polymer component that constitutes it can be depolymerized and decomposed, whereby layer L that does not contain the ester bond-containing polymer component can be separated from the laminate. O It can be separated.

[0025] In addition, layer L containing the ester bond-containing polymer component E may contain two or more ester bond-containing polymer components, and layer L that does not contain the ester bond-containing polymer component can be separated from the laminate. O Within the range where separation is possible, it may contain components other than the ester bond-containing polymer component (for example, fillers and polymers other than the ester bond-containing polymer component). Also, layer L that does not contain the ester bond-containing polymer component O only needs to be a layer composed of components other than the ester bond-containing polymer component, and may contain two or more components other than the ester bond-containing polymer component.

[0026] Further, as the laminate as a composite material, for example, layer L that does not contain the ester bond-containing polymer component O may be adhered to each other through layer L that contains the ester bond-containing polymer component as an adhesive layer, and a laminate having a structure of three or more layers may be used. For example, the laminate may have a three-layer structure of "layer L that does not contain the ester bond-containing polymer component E / layer L that contains the ester bond-containing polymer component O_1 / layer L that does not contain the ester bond-containing polymer component E O_2 ". In this case, by bringing the separation chemical solution of the present invention into contact, the layer L that contains the ester bond-containing polymer component E O_1 can be depolymerized and decomposed, whereby layer L that does not contain the ester bond-containing polymer component O_2 and layer L that does not contain the ester bond-containing polymer component E can be separated from the laminate.

[0027] Such a laminate is not particularly limited. For example, layer L that contains the ester bond-containing polymer component EExamples include packaging materials such as packaging containers containing the material, optical equipment component materials such as optical films, and industrial component materials such as electronic equipment, batteries, capacitors, and magnetic tapes. Examples of packaging containers include retort pouch packaging containers for retort pouch foods, metal cans for beverages, refill pouches for liquid detergents, packaging containers for confectionery, and packaging containers for pharmaceuticals. When the laminate is a packaging container, the components constituting the packaging container can be suitably separated, thereby enabling recycling. Furthermore, when the laminate is a packaging container, it may also include layers for providing product information or design features, such as an ink layer.

[0028] The ester bond-containing polymer component constituting the mixed or composite material can be any polymer having ester bonds in its main chain structure, and is not particularly limited, but examples include polyester, polyester polyol, and polyester polyol-based polyurethane. Polyesters are not particularly limited, but examples include aromatic polyester, fully aromatic polyester, polycarbonate ester, and aliphatic polyester, with aromatic polyester being preferred. Aromatic polyesters contain diol units and dicarboxylic acid units. Examples of diol compounds for forming diol units include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, 1,6-hexylene glycol, cyclohexanedimethanol, and ethylene oxide adducts of bisphenol A, with ethylene glycol being preferred among these. Examples of dicarboxylic acid compounds for forming dicarboxylic acid units include aromatic dicarboxylic acids and their derivatives, such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, and francicarboxylic acid, with terephthalic acid being preferred among these. Specific examples of polyester include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polyethylene furanoate, among which polyethylene terephthalate, a copolymer of ethylene glycol and terephthalic acid, is preferred. The above-mentioned polyester is not limited to that derived from petroleum raw materials, but may also be derived from plant raw materials, or may be a recycled polyester derived from these petroleum or plant raw material polyesters. Furthermore, the above-mentioned polyester may be used individually or in mixtures.

[0029] Polyethylene terephthalate may contain units consisting of dicarboxylic acids other than ethylene glycol that can copolymerize with ethylene glycol and terephthalic acid, within its total monomer units. Examples of dicarboxylic acids other than terephthalic acid include malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedionic acid, eicosanedionic acid, pimelic acid, azelaic acid, methylmalonic acid and ethylmalonic acid, adamantanedicarboxylic acid, norbornenedicarboxylic acid, cyclohexanedicarboxylic acid, decalindicarboxylic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 5-sodium sulfisoisophthalic acid, phenylendanedicarboxylic acid, anthracenedicarboxylic acid, phenantradicarboxylic acid, 9,9'-bis(4-carboxyphenyl)fluorenic acid, 2,5-franzicarboxylic acid and their ester derivatives, among which isophthalic acid is preferred.

[0030] Polyethylene terephthalate may contain units consisting of diols other than ethylene glycol that can copolymerize with ethylene glycol and terephthalic acid in the total monomer units. Such diols other than ethylene glycol include 1,2-propanediol, 1,3-propanediol, butanediol, 2-methyl-1,3-propanediol, hexanediol, neopentyl glycol, cyclohexanedimethanol, cyclohexanediethanol, decahydronaphthalenedimethanol, decahydronaphthalenediethanol, norbornanediethanol, norbornanediethanol, tricyclodecanediethanol, tricyclodecanediethanol, tetracyclododecanediethanol, tetracyclododecanediethanol, decalindiethanol, decalindiethanol, 5-methylol-5-ethyl-2-(1,1-dimethyl-2-hydroxyethyl Examples include (L)-1,3-dioxane, cyclohexanediol, bicyclohexyl-4,4'-diol, 2,2-bis(4-hydroxycyclohexylpropane), 2,2-bis(4-(2-hydroxyethoxy)cyclohexyl)propane, cyclopentanediol, 3-methyl-1,2-cyclopentadiol, 4-cyclopentene-1,3-diol, adamandiol, paraxylene glycol, bisphenol A, bisphenol S, styrene glycol, trimethylolpropane, pentaerythritol, diethylene glycol, triethylene glycol, and bis-β-hydroxyethyl terephthalate (BHET), among which diethylene glycol is preferred.

[0031] Furthermore, the ester bond-containing polymer component may be any polymer having ester bonds in its main chain structure, or a polymer that also has ester bonds in its side chains. However, if the polymer has ester bonds only in its side chains, when the separation solution of the present invention is applied, the ester bonds in the side chains will decompose, but the decomposition of the main chain structure will not progress, and depolymerization will not proceed. Therefore, polymers having ester bonds only in their side chains are undesirable.

[0032] Furthermore, components other than the ester bond-containing polymer component that constitute the mixed or composite material are not particularly limited, but include polymer components that do not have ester bonds in their main chain structure, low molecular weight organic components, and inorganic components. Various polymer materials can be used as polymer components that do not have ester bonds in their main chain structure, and are not particularly limited, but include polyolefin resins such as polyethylene and polypropylene, polyamide resins such as nylon, acrylic resins such as polymethyl methacrylate, fluororesins such as ABS resin and polytetrafluoroethylene, polyvinyl alcohol-based resins such as polyvinyl alcohol and ethylene vinyl alcohol copolymer, resin materials such as polystyrene, polycarbonate, and polyvinyl chloride; rubber materials such as acrylonitrile butadiene rubber, styrene butadiene rubber, butadiene rubber, isoprene rubber, acrylic rubber, ethylene propylene rubber, urethane rubber, fluororubber, and silicone rubber; natural fibers such as cotton and hemp, and cellulose-based materials such as rayon; and polyurethanes consisting of components other than the ester bond-containing polymer component, such as polyether polyol-based polyurethanes. Low molecular weight organic and inorganic components that do not have ester bonds in their main chain structure are not particularly limited, but include various additives commonly used with polymer materials such as polymerization catalysts, polymerization stabilizers, plasticizers, compatibilizers, light stabilizers, antioxidants, UV absorbers, flame retardants, colorants, pigments, fillers, mold release agents, antistatic agents, fragrances, foaming agents, and antibacterial / antifungal agents. More specifically, examples include metals and metal oxides such as aluminum and steel, silicate minerals, inorganic fiber materials such as carbon fiber and glass fiber, carbon black, and titanium dioxide.

[0033] The separation solution of the present invention is used for separating the above-mentioned mixed materials or composite materials, and contains an alcohol, a basic catalyst, and an auxiliary solvent.

[0034] The alcohol can be any compound having an alcoholic hydroxyl group and is not particularly limited, but examples include monoalcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and amyl alcohol; and dialcohols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and 2,3-butanediol. These alcohols may be used individually or in combination of two or more. Among these alcohols, monoalcohols are preferred, methanol or ethanol is more preferred, and methanol is particularly preferred, from the viewpoint of more easily promoting the depolymerization of the ester bond-containing polymer component.

[0035] The base catalyst can be any catalyst that promotes the decomposition reaction of ester bonds via alcohol, and is not particularly limited, but examples include carbonates such as potassium carbonate, calcium carbonate, sodium carbonate, barium carbonate, magnesium carbonate, lithium carbonate, ammonium carbonate, copper(II) carbonate, iron(II) carbonate, and silver(I) carbonate; alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide; alkali metal alkoxides such as lithium methoxide, lithium ethoxide, lithium tert-butoxide, sodium methoxide, sodium ethoxide, sodium tert-butoxide, potassium methoxide, potassium ethoxide, and potassium tert-butoxide; and alkaline earth metal alkoxides such as calcium dimethoxide, calcium diethoxide, calcium ditert-butoxide, magnesium dimethoxide, magnesium diethoxide, and magnesium ditert-butoxide. These base catalysts may be used individually or in combination of two or more. Among these, carbonates, alkali metal hydroxides, and alkali metal alkoxides are preferred as base catalysts. Among carbonates, potassium carbonate is more preferred. Among alkali metal hydroxides, sodium hydroxide and potassium hydroxide are more preferred. Among alkali metal alkoxides, sodium methoxide and potassium methoxide are more preferred. Alkali metal hydroxides are even more preferred, and among alkali metal hydroxides, sodium hydroxide and potassium hydroxide are even more preferred.

[0036] The auxiliary solvent is an organic solvent without alcoholic hydroxyl groups that enhances the impregnation of the separation solution of the present invention into the ester bond-containing polymer component, thereby facilitating the depolymerization of the ester bond-containing polymer component. Any good solvent for the ester bond-containing polymer component can be used as the auxiliary solvent without particular limitations. Examples include dialkyl ketones such as acetone, methyl ethyl ketone, and diethyl ketone; nitriles such as acetonitrile; halogenated alkanes such as dichloromethane and chloroform; and cyclic ethers such as tetrahydrofuran. The auxiliary solvent may be used alone or in combination of two or more. Among these, dialkyl ketones, halogenated alkanes, and cyclic ethers are preferred as auxiliary solvents, with acetone, dichloromethane, and tetrahydrofuran being more preferred. From the viewpoint of ease of removal (ease of solvent removal from the solution after depolymerization), acetone is even more preferred.

[0037] In the separation solution of the present invention, the content ratio of alcohol and auxiliary solvent is preferably in the range of 10 / 90 to 90 / 10, more preferably 20 / 80 to 90 / 10, even more preferably 25 / 75 to 85 / 15, even more preferably 30 / 70 to 80 / 20, and particularly preferably 40 / 60 to 80 / 20, expressed as a weight ratio of "alcohol / auxiliary solvent". By setting the content ratio of alcohol and auxiliary solvent within the above range, the time required for separating components from mixed or composite materials using the separation solution can be shortened, thereby effectively increasing the efficiency of the separation process. Although not particularly limited, the total amount of alcohol and auxiliary solvent in the separation solution of the present invention is preferably 80 to 99.9% by weight, more preferably 85 to 99.7% by weight, even more preferably 90 to 99.7% by weight, and particularly preferably 95 to 99.7% by weight, relative to the total amount of the separation solution.

[0038] Furthermore, the amount of base catalyst in the separation solution of the present invention is preferably 0.1 to 20% by weight, more preferably 0.3 to 15% by weight, even more preferably 0.3 to 10% by weight, and particularly preferably 0.3 to 5% by weight, relative to the total amount of the separation solution. By setting the amount of base catalyst within the above range, the time required for separating components from mixed or composite materials using the separation solution can be shortened, thereby effectively increasing the efficiency of the separation process.

[0039] The separation chemical solution of the present invention is a combination of alcohol, an auxiliary solvent, and a base catalyst. Monoalcohols and dialkylketones and alkali metal hydroxides, dialcohols and dialkylketones and alkali metal hydroxides, monoalcohols and halide alkanes and alkali metal hydroxides, dialcohols and halide alkanes and alkali metal hydroxides, monoalcohols and cyclic ethers and alkali metal hydroxides, dialcohols and cyclic ethers and alkali metal hydroxides, monoalcohols and nitriles and alkali metal hydroxides, dialcohols and nitriles and alkali metal hydroxides, Monoalcohols and dialkylketones and carbonates, dialcohols and dialkylketones and carbonates, monoalcohols and halide alkanes and carbonates, dialcohols and halide alkanes and carbonates, monoalcohols and cyclic ethers and carbonates, dialcohols and cyclic ethers and carbonates, monoalcohols and nitriles and carbonates, dialcohols and nitriles and carbonates, Preferably, the combinations are monoalcohol, dialkylketone and alkali metal alkoxide; dialcohol, dialkylketone and alkali metal alkoxide; monoalcohol, halogenated alkane and alkali metal alkoxide; dialcohol, halogenated alkane and alkali metal alkoxide; monoalcohol, cyclic ether and alkali metal alkoxide; dialcohol, cyclic ether and alkali metal alkoxide; monoalcohol, nitrile and alkali metal alkoxide; or dialcohol, nitrile and alkali metal alkoxide. Among these, Methanol, acetone, and sodium hydroxide; ethanol, acetone, and sodium hydroxide; ethylene glycol, acetone, and sodium hydroxide; methanol, dichloromethane, and sodium hydroxide; ethanol, dichloromethane, and sodium hydroxide; ethylene glycol, dichloromethane, and sodium hydroxide; methanol, tetrahydrofuran, and sodium hydroxide; ethanol, tetrahydrofuran, and sodium hydroxide; ethylene glycol, tetrahydrofuran, and sodium hydroxide, Methanol, acetonitrile, and sodium hydroxide; ethanol, acetonitrile, and sodium hydroxide; ethylene glycol, acetonitrile, and sodium hydroxide; Methanol, acetone, and potassium hydroxide; ethanol, acetone, and potassium hydroxide; ethylene glycol, acetone, and potassium hydroxide; methanol, dichloromethane, and potassium hydroxide; ethanol, dichloromethane, and potassium hydroxide; ethylene glycol, dichloromethane, and potassium hydroxide; methanol, tetrahydrofuran, and potassium hydroxide; ethanol, tetrahydrofuran, and potassium hydroxide; ethylene glycol, tetrahydrofuran, and potassium hydroxide, Methanol, acetonitrile, and potassium hydroxide; ethanol, acetonitrile, and potassium hydroxide; ethylene glycol, acetonitrile, and potassium hydroxide; Methanol and acetone and potassium carbonate, ethanol and acetone and potassium carbonate, ethylene glycol and acetone and potassium carbonate, methanol and dichloromethane and potassium carbonate, ethanol and dichloromethane and potassium carbonate, ethylene glycol and dichloromethane and potassium carbonate, methanol and tetrahydrofuran and potassium carbonate, ethanol and tetrahydrofuran and potassium carbonate, ethylene glycol and tetrahydrofuran and potassium carbonate, Methanol, acetonitrile, and potassium carbonate; ethanol, acetonitrile, and potassium carbonate; ethylene glycol, acetonitrile, and potassium carbonate; Methanol and acetone and sodium methoxide, ethanol and acetone and sodium methoxide, ethylene glycol and acetone and sodium methoxide, methanol and dichloromethane and sodium methoxide, ethanol and dichloromethane and sodium methoxide, ethylene glycol and dichloromethane and sodium methoxide, methanol and tetrahydrofuran and sodium methoxide, ethanol and tetrahydrofuran and sodium methoxide, ethylene glycol and tetrahydrofuran and sodium methoxide, Methanol, acetonitrile, and sodium methoxide; ethanol, acetonitrile, and sodium methoxide; ethylene glycol, acetonitrile, and sodium methoxide; Methanol and acetone and potassium methoxide, ethanol and acetone and potassium methoxide, ethylene glycol and acetone and potassium methoxide, methanol and dichloromethane and potassium methoxide, ethanol and dichloromethane and potassium methoxide, ethylene glycol and dichloromethane and potassium methoxide, methanol and tetrahydrofuran and potassium methoxide, ethanol and tetrahydrofuran and potassium methoxide, ethylene glycol and tetrahydrofuran and potassium methoxide, Preferably, the combinations are methanol, acetonitrile and potassium methoxide, ethanol, acetonitrile and potassium methoxide, or ethylene glycol, acetonitrile and potassium methoxide. More preferably, the combinations are methanol, acetone, and sodium hydroxide, or methanol, acetone, and potassium hydroxide.

[0040] Furthermore, the separation solution of the present invention may contain other components in addition to alcohol, a basic catalyst, and an auxiliary solvent. Examples of such other components include water, adsorbents, compatibilizers, defoamers, and viscosity modifiers. On the other hand, when water is included as another component, the impregnation of the separation solution into ester-bonded polymer components tends to decrease. Therefore, it is preferable to keep the water content in the separation solution to 10% by weight or less, more preferably 5% by weight or less, even more preferably 1% by weight or less, and particularly preferable to substantially contain no water. In other words, it is preferable to not intentionally add water and to keep the water content as an unavoidable component to 5000 ppm by weight or less.

[0041] <Separation method using separation chemicals> The separation method of the present invention is a separation method for separating at least one component from a mixed material or composite material composed of two or more components, each containing at least an ester bond-containing polymer component having an ester bond in its main chain structure. The invention comprises the step of bringing the mixed material or composite material into contact with the separation chemical solution of the present invention described above.

[0042] In the separation method of the present invention, the method of bringing the mixed material or composite material into contact with the separation chemical solution is not particularly limited, but immersion of the mixed material or composite material in the separation chemical solution is preferred, and stirring or shaking operations may be performed as needed.

[0043] The temperature at which the mixed or composite material is brought into contact with the separation chemical solution is not particularly limited, but it is preferable that the temperature be below the boiling point of methanol and the auxiliary solvent contained in the mixed solvent. Specifically, the temperature at which the material is brought into contact with the separation chemical solution is preferably 0 to 65°C, more preferably 20 to 60°C, and even more preferably 35 to 55°C, from the viewpoint of eliminating the need for heating and cooling and saving energy.

[0044] The contact time when the mixed material or composite material is brought into contact with the separation chemical solution should be such that the separation of each component from the mixed material or composite material is completed. While not particularly limited, it is preferably 0.5 to 24 hours, and more preferably 1 to 8 hours. As described above, the separation chemical solution of the present invention makes it possible to suitably separate at least one component from the mixed material or composite material in a relatively short time, even under relatively mild conditions (relatively low temperature conditions).

[0045] After contacting the mixed or composite material with a separation solution to complete the separation, the components may be subjected to further isolation as needed. While not limited to these methods, examples of isolation methods include solid-liquid separation such as sieving, filter pressing, and centrifugal filtration, as well as crystallization, purification by distillation, magnetic separation, and specific gravity separation. [Examples]

[0046] Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

[0047] [Example 1] (Preparation of separation chemical solution) A mixed solvent was prepared by mixing methanol as an alcohol and acetone as an auxiliary solvent in a methanol / acetone weight ratio of 30 / 70. Then, 0.13 mmol of potassium carbonate (K2CO3) as a base catalyst was added to 2.5 mL of the resulting mixed solvent to prepare a separation solution (amount of base catalyst in the separation solution: 0.90% by weight). The resulting separation solution was substantially water-free (water content was 5000 ppm by weight or less).

[0048] (Immersion separation test) The separation solution prepared above was heated to 50°C, and two 1cm square test laminates 1 were immersed in the separation solution maintained at 50°C. The temperature of the separation solution was maintained at 50°C using an aluminum block temperature controller (Tosoh, DF-8321H), and the immersion separation test was performed by shaking at 100 rpm. The test laminate 1 used was a six-layer laminate consisting of a PET layer, an ink layer, a polyester polyol-based urethane layer (adhesive layer), a nylon layer, a polyester polyol-based urethane layer (adhesive layer), and a polypropylene layer.

[0049] Three hours after the start of the immersion separation test, the polypropylene layer peeled off. After five hours, the nylon layer, PET layer, and ink layer peeled off, and after eight hours, the PET layer disappeared. This result confirms that the action of the separation chemical solution causes the depolymerization and decomposition of the polyester polyol-based urethane layer, which acts as an adhesive layer, and the outermost PET layer. As a result, the polypropylene layer separates after three hours, and the nylon layer, PET layer, and ink layer separate after five hours, making it possible to suitably recycle the polypropylene layer and nylon layer. Figures 1(A) to 1(C) show sample photographs of Example 1. Figure 1(A) is a photograph of test laminate 1 before the immersion separation test, Figure 1(B) is a photograph of the polypropylene layer separated by the immersion separation test, and Figure 1(C) is a photograph of the nylon layer separated by the immersion separation test.

[0050] [Example 2] An immersion separation test was conducted in the same manner as in Example 1, except that the temperature of the separation solution was changed to 23°C. As a result of the immersion separation test, the polypropylene layer and the nylon layer separated after 24 hours, confirming that the polypropylene layer and the nylon layer can be suitably recycled.

[0051] [Example 3] (Preparation of separation chemical solution) A separation solution was prepared in the same manner as in Example 1, except that the mixing ratio of methanol as the alcohol and acetone as the auxiliary solvent was 50 / 50 in terms of methanol / acetone by weight (amount of base catalyst in the separation solution: 0.90% by weight). The resulting separation solution was substantially water-free (water content was 5000 ppm by weight or less).

[0052] (Immersion separation test) An immersion separation test was conducted in the same manner as in Example 1, except that the chemical solution prepared above was used as the separation solution. As a result of the immersion separation test, the polypropylene layer separated after 2 hours, and then the nylon layer separated after 3 hours, confirming that the polypropylene layer and the nylon layer can be suitably recycled.

[0053] [Example 4] (Preparation of separation chemical solution) A separation solution was prepared in the same manner as in Example 1, except that the mixing ratio of methanol as the alcohol and acetone as the auxiliary solvent was 80 / 20 in terms of methanol / acetone by weight (amount of base catalyst in the separation solution: 0.90% by weight). The resulting separation solution was substantially water-free (water content was 5000 ppm by weight or less).

[0054] (Immersion separation test) An immersion separation test was conducted in the same manner as in Example 1, except that the chemical solution prepared above was used as the separation solution. As a result of the immersion separation test, the polypropylene layer separated after 5 hours, and then the nylon layer separated after 8 hours, confirming that the polypropylene layer and the nylon layer can be suitably recycled.

[0055] [Example 5] (Preparation of separation chemical solution) A separation solution was prepared in the same manner as in Example 1, except that dichloromethane was used instead of acetone as an auxiliary solvent (methanol / dichloromethane = 30 / 70 (weight ratio)) (amount of base catalyst in the separation solution: 0.61% by weight). The resulting separation solution was substantially water-free (water content was 5000 ppm by weight or less).

[0056] (Immersion separation test) An immersion separation test was conducted in the same manner as in Example 1, except that the chemical solution prepared above was used as the separation solution. As a result of the immersion separation test, the polypropylene layer and the nylon layer separated after 3 hours, confirming that the polypropylene layer and the nylon layer can be suitably recycled.

[0057] [Example 6] (Preparation of separation chemical solution) A separation solution was prepared in the same manner as in Example 1, except that tetrahydrofuran was used instead of acetone as an auxiliary solvent (methanol / tetrahydrofuran = 30 / 70 (weight ratio)) (amount of base catalyst in the separation solution: 0.83% by weight). The resulting separation solution was substantially water-free (water content was 5000 ppm by weight or less).

[0058] (Immersion separation test) An immersion separation test was conducted in the same manner as in Example 1, except that the chemical solution prepared above was used as the separation solution. As a result of the immersion separation test, the polypropylene layer and the nylon layer were separated after 8 hours, confirming that the polypropylene layer and the nylon layer can be suitably recycled.

[0059] [Comparative Example 1] (Preparation of separation chemical solution) The separation solution was prepared in the same manner as in Example 1, except that acetone was not used as an auxiliary solvent. The resulting separation solution was substantially water-free (water content was 5000 ppm by weight or less).

[0060] (Immersion separation test) An immersion separation test was conducted in the same manner as in Example 1, except that the chemical solution prepared above was used as the separation solution. As a result of the immersion separation test, no delamination of any of the layers occurred even after 24 hours.

[0061] [Comparative Example 2] An immersion separation test was conducted in the same manner as in Example 1, except that Test Laminate 2 was used instead of Test Laminate 1. As a result of the immersion separation test, no delamination of any of the layers occurred even after 24 hours. Test Laminate 2 was a three-layer laminate consisting of an ethylene vinyl alcohol copolymer layer, a maleic anhydride-modified polyolefin resin layer (adhesive layer), and a polypropylene layer.

[0062] Table 1 summarizes the examples 1-6 and comparative examples 1 and 2.

[0063] [Table 1]

[0064] [Examples 7-13] (Preparation of separation chemical solution) The separation solution was prepared in the same manner as in Example 1, except that potassium hydroxide was used instead of potassium carbonate as the base catalyst, and the mixing ratio of methanol as the alcohol and acetone as the auxiliary solvent was set to the value in Table 2 in terms of the "methanol / acetone" weight ratio (amount of base catalyst in the separation solution: 0.37% by weight). The obtained separation solution was substantially water-free (water content was 5000 ppm by weight or less). The amount of potassium hydroxide was 0.13 mmol, the same as in Example 1 (the same applies to Examples 17, 18, and 21 described later).

[0065] (Immersion separation test) An immersion separation test was conducted in the same manner as in Example 1, except that the chemical solution prepared above was used as the separation solution. As a result of the immersion separation test, the polypropylene layer separated at the time elapsed shown in Table 2, followed by the separation of the nylon layer. This confirmed that the polypropylene layer and the nylon layer can be suitably recycled.

[0066] [Comparative Example 3] (Preparation of separation chemical solution) The separation solution was prepared in the same manner as in Example 1, except that potassium hydroxide was used instead of potassium carbonate as the base catalyst, and acetone was not used as the auxiliary solvent. The resulting separation solution was substantially water-free (water content was 5000 ppm by weight or less).

[0067] (Immersion separation test) An immersion separation test was conducted in the same manner as in Example 1, except that the chemical solution prepared above was used as the separation solution. As a result of the immersion separation test, no delamination of any of the layers occurred even after 24 hours.

[0068] Table 2 summarizes the details of Examples 7-13 and Comparative Example 3.

[0069] [Table 2]

[0070] [Example 14] (Preparation of separation chemical solution) A separation solution was prepared in the same manner as in Example 1, except that sodium methoxide was used instead of potassium carbonate as the base catalyst (amount of base catalyst in the separation solution: 0.35% by weight). The resulting separation solution was substantially water-free (water content was 5000 ppm by weight or less). The amount of sodium methoxide was 0.13 mmol, the same as in Example 1.

[0071] (Immersion separation test) An immersion separation test was conducted in the same manner as in Example 1, except that the chemical solution prepared above was used as the separation solution. As a result of the immersion separation test, the polypropylene layer separated after 5 hours, and then the nylon layer separated after another 5 hours, confirming that the polypropylene layer and the nylon layer can be suitably recycled.

[0072] Table 3 shows an overview of Example 14.

[0073] [Table 3]

[0074] [Example 15] Except for using test molded bodies 1 (totaling 25.0 mg) cut into 3-10 mg pieces instead of test laminate 1, the immersion separation test was performed in the same manner as in Example 1 using the separation chemical solution obtained in the same manner as in Example 1. As test molded bodies 1, glass fiber reinforced polybutylene terephthalate molded bodies (chopsticks; chopstick-shaped molded bodies of polybutylene terephthalate with glass fibers added) were used.

[0075] After 24 hours following the start of the immersion separation test, the total weight of the molded body was 9.6 mg, representing a weight reduction of 61.5%. Furthermore, when the separation solution from which the molded body was removed was filtered, glass fibers were detected on the filter paper. This confirmed that it is possible to effectively separate glass fibers from fiber-reinforced plastic.

[0076] [Example 16] Except for using a 23 mg test fabric 1 measuring 1 cm square instead of test laminate 1, the immersion separation test was performed in the same manner as in Example 1 using the separation chemical solution obtained in the same manner as in Example 1. The test fabric 1 used was a blended fabric consisting of 53% cotton and 47% polyester by weight.

[0077] After 24 hours following the start of the immersion separation test, the total weight of the woven fabric was 11.6 mg, representing a 49.6% weight reduction. Furthermore, the remaining fabric was confirmed to be cotton. This confirmed that it is possible to effectively separate cotton from blended fabrics.

[0078] [Example 17] Except for using potassium hydroxide instead of potassium carbonate as the base catalyst, the separation solution was prepared in the same manner as in Example 15, and the immersion separation test was performed using test molded body 1 in the same manner as in Example 15.

[0079] After 24 hours following the start of the immersion separation test, the total weight of the molded body was 5.0 mg, representing an 80.0% weight reduction. Furthermore, when the separation solution from which the molded body was removed was filtered, glass fibers were detected on the filter paper. This confirmed that it is possible to effectively separate glass fibers from fiber-reinforced plastic.

[0080] [Example 18] The separation solution was prepared in the same manner as in Example 16, except that potassium hydroxide was used instead of potassium carbonate as the base catalyst. An immersion separation test was then performed using test fabric 1 in the same manner as in Example 16.

[0081] After 24 hours following the start of the immersion separation test, the total weight of the woven fabric was 12.0 mg, representing a weight reduction of 47.7%. Furthermore, when the separation solution from which the molded body was removed was filtered, glass fibers were detected on the filter paper. The remaining fabric was confirmed to be cotton. This confirmed that it is possible to effectively separate cotton from blended fabrics.

[0082] [Example 19] Except for using a 0.5 cm square test metal laminate 1 instead of test laminate 1, the immersion separation test was performed in the same manner as in Example 1 using the separation chemical solution obtained in the same manner as in Example 1. The test metal laminate 1 used was a metal laminate (aluminum can for soft drinks) consisting of five layers from the outside: a finishing varnish layer, an ink layer, a PET resin layer, an aluminum can body metal layer, and a PET resin layer.

[0083] After 24 hours following the start of the immersion separation test, the ink layer and the aluminum can shell metal layer were recovered in a separated state. At this time, no PET resin layer was observed on the surface of the recovered material. In other words, this result confirmed that the PET resin layer depolymerizes and decomposes due to the action of the separation chemical, making it possible to suitably recycle the aluminum can shell metal layer.

[0084] [Example 20] Except for using a 0.5 cm square test metal laminate 2 instead of test laminate 1, the immersion separation test was performed in the same manner as in Example 1 using the separation chemical solution obtained in the same manner as in Example 1. As test metal laminate 2, a metal laminate (steel can for soft drinks) consisting of five layers from the outside inward was used: a finishing varnish layer, an ink layer, a PET resin layer, a steel can body metal layer, and a PET resin layer.

[0085] After 24 hours following the start of the immersion separation test, the ink layer and the steel can body metal layer were recovered in a separated state. At this time, no PET resin layer was observed on the surface of the recovered material. In other words, this result confirmed that the PET resin layer depolymerizes and decomposes due to the action of the separation chemical, making it possible to suitably recycle the steel can body metal layer.

[0086] [Example 21] Except for using potassium hydroxide instead of potassium carbonate as the base catalyst, the separation solution was prepared in the same manner as in Example 19, and the immersion separation test was performed using test metal laminate 1 in the same manner as in Example 19.

[0087] After 24 hours following the start of the immersion separation test, the ink layer and the aluminum can shell metal layer were recovered in a separated state. At this time, no PET resin layer was observed on the surface of the recovered material. In other words, this result confirmed that the PET resin layer depolymerizes and decomposes due to the action of the separation chemical, making it possible to suitably recycle the aluminum can shell metal layer.

[0088] [Comparative Example 4] Except for not using a base catalyst, the separation solution was prepared in the same manner as the separation solution used in Example 19, and the immersion separation test was performed using test metal laminate 1 in the same manner as in Example 19.

[0089] Even after 24 hours had elapsed since the start of the immersion separation test, no delamination of any of the layers occurred.

[0090] [Comparative Example 5] Except for not using a base catalyst and not using methanol as the alcohol, the separation solution was prepared in the same manner as the separation solution used in Example 19, and the immersion separation test was performed using test metal laminate 1 in the same manner as in Example 19.

[0091] Even after 24 hours had elapsed since the start of the immersion separation test, no delamination of any of the layers occurred.

Claims

1. A separation solution for separating at least one component from a mixed material or composite material composed of two or more components, each containing at least an ester bond-containing polymer component having an ester bond in its main chain structure, by depolymerization, It contains alcohol, a basic catalyst, and an auxiliary solvent as essential components. The alcohol is at least one monoalcohol selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and amyl alcohol. The auxiliary solvent is at least one dialkyl ketone selected from the group consisting of acetone, methyl ethyl ketone, and diethyl ketone, at least one halogenated alkane selected from the group consisting of dichloromethane, and chloroform, or tetrahydrofuran. A separation chemical solution that contains virtually no water.

2. A separation chemical solution according to claim 1, A separation chemical solution wherein the mixed material or composite material is a laminate having a layer containing the ester bond-containing polymer component.

3. The separation chemical solution according to claim 2, The aforementioned laminate is a packaging container for a separation chemical solution.

4. A separation chemical solution according to any one of claims 1 to 3, A separation solution in which the auxiliary solvent is acetone.

5. A separation chemical solution according to any one of claims 1 to 3, A separation solution in which the content ratio of the alcohol to the auxiliary solvent is in the range of 10 / 90 to 90 / 10 in terms of the weight ratio of "alcohol / auxiliary solvent".

6. A separation chemical solution according to any one of claims 1 to 3, A separation chemical solution wherein the basic catalyst is at least one selected from potassium carbonate, sodium hydroxide, potassium hydroxide, sodium alkoxide, and potassium alkoxide.

7. A separation chemical solution according to any one of claims 1 to 3, A separation solution in which the total amount of the alcohol and the auxiliary solvent in the separation solution is 80 to 99.9% by weight of the entire separation solution.

8. A separation method for separating at least one component from a mixed material or composite material composed of two or more components, each containing at least an ester bond-containing polymer component having an ester bond in its main chain structure, by depolymerization, The process includes contacting the aforementioned mixed material or composite material with a separation solution containing an alcohol, a basic catalyst, and an auxiliary solvent as essential components. The alcohol is at least one monoalcohol selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and amyl alcohol. The auxiliary solvent is at least one dialkyl ketone selected from the group consisting of acetone, methyl ethyl ketone, and diethyl ketone, at least one halogenated alkane selected from the group consisting of dichloromethane, and chloroform, or tetrahydrofuran. The separation method wherein the separation solution substantially does not contain water.

9. A separation method according to claim 8, A separation method comprising contacting the mixed material or composite material with the separation chemical solution under temperature conditions of 0 to 65°C.

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