Decomposition method

Abstract

To provide a new method for decomposing a treating object (a) having a constituent component containing at least one urethane bond.SOLUTION: When the molar ratio X / Y is adjusted to 0.002 or more and the molar ratio Z / Y is adjusted to 0.5 or more and 40 or less in the treatment liquid containing the catalyst (b), the nucleophilic agent (c), and the solvent (d) (where Xmol%, Ymol%, and Zmol% represent the molar fractions of the respective components (provided that X + Y + Z = 100)), the urethane bond contained in the treatment target (a) can be decomposed at a temperature lower than that in the related art, particularly at a temperature lower than 100 °C.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for decomposing a processing object.

[0002] In the present invention, the term "subject to be treated" refers to an object having at least one chemical part. In addition, a series of operations in the present invention will be abbreviated as "treatment." Here, the "chemical part" refers to a component that is bonded via a specific chemical bond. That is, in the present invention, it refers to a component that can be decomposed under conditions in which a specific catalyst, nucleophile, and solvent are appropriately combined and at a temperature of less than 100°C (hereinafter, such reaction conditions may be abbreviated as "the reaction conditions of the present invention"). On the other hand, a component that is not bonded via a specific chemical bond, i.e., a component that cannot be decomposed and remains under the reaction conditions of the present invention, is distinguished as a "material part." The processing target of the present invention may include a material part.

[0003] In the present invention, the term "decomposition" refers to a process of causing a nucleophilic substitution reaction at the specific chemical bond to separate the compound into components derived from two or more constituent elements. Hereinafter, such a chemical reaction will be abbreviated as a "decomposition reaction." Therefore, in the present invention, "decomposition" does not include a case in which only the chemical part contained in the target to be treated is simply dissolved in a solvent without being separated into components derived from two or more constituent elements. In the reaction conditions of the present invention, the specific chemical bond that undergoes the nucleophilic substitution reaction is at least one selected from a urethane bond, an ester bond, and a carbonate bond. On the other hand, nucleophilic substitution reaction does not occur in a urea bond or an amide bond. Therefore, for example, when a urethane bond and an amide bond coexist in the treatment target, the urethane bond can be selectively decomposed, while the amide bond remains undecomposed, allowing material recycling of the material part having the amide bond. [Background technology]

[0004] Plastics are inexpensive and highly durable materials. Due to their convenience, polyethylene terephthalate (PET) in particular has been widely used in a wide range of applications, including fibers, films, and bottles, and its production and consumption have rapidly increased over the past few decades. However, despite its durability, PET is not easily biodegradable, leading to the filling of landfills around the world and the resulting marine pollution caused by microplastics, which is a major social issue in terms of environmental destruction. Given this background, there is a need for the development of recycling technologies for PET and other plastic waste. Compared to Europe and the United States, Japan has a higher proportion of thermal recycling, which utilizes the heat energy generated during incineration, but there are concerns about global warming due to carbon dioxide emissions. As a result, much research has been conducted into chemical recycling of polyester products, i.e., methods of chemically converting polyester products into monomers, recovering them, and reusing these monomers.

[0005] Patent Document 1 discloses a method for continuously producing aromatic dimethyl dicarboxylic acid and dihydric alcohol, which are monomer components of aromatic polyester such as PET, from the aromatic polyester using supercritical alcohol, but requires high temperatures of 300°C or higher.

[0006] Patent Document 2 discloses a method for producing dimethyl terephthalate by depolymerizing polyester with alkylene glycol and then transesterifying it with methanol. The method is characterized by the use of a specific calcium-containing catalyst, which allows the second-stage transesterification reaction to be carried out at temperatures between 35°C and 90°C. The first-stage depolymerization reaction is carried out in excess alkylene glycol heated to 120-230°C. Furthermore, in order to reduce the amount of methanol used in the second-stage transesterification reaction, it is preferable to concentrate the depolymerized liquid obtained after the depolymerization reaction by distilling and evaporating a portion of the alkylene glycol from the depolymerized liquid. Furthermore, it has been shown that the purity of dimethyl terephthalate can be increased by separating the resulting dimethyl terephthalate crystals into solids and liquids using solid-liquid separation means such as centrifugation, or by purifying the resulting crude dimethyl terephthalate by distillation when a highly pure product is desired. Therefore, the recycling process involves a large number of steps, consuming a lot of energy. Considering the effective use of limited resources, a method with many steps is not desirable, and it is also desirable to reduce energy consumption.

[0007] In contrast to these prior art documents, research has already been conducted into methods for decomposing polyesters at temperatures below 100°C. Patent Document 3 discloses a process for converting polyethylene terephthalate or poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate) into terephthalic acid esters by depolymerization. The process includes contacting the polyester with a solvent for swelling, an alcoholic solvent, and a substoichiometric amount of alkoxide. In particular, the examples use dichloromethane or dimethyl sulfoxide as the solvent for swelling the polyester, methanol as the alcoholic solvent, and a substoichiometric amount of sodium methoxide as the alkoxide, and demonstrate that polyethylene terephthalate is converted to dimethyl terephthalate at 50 to 60°C.

[0008] Research is also underway into methods for decomposing polycarbonate resins with high reactivity, even under mild conditions with little environmental impact. Patent Document 4 discloses a method for producing bisphenols by decomposing a polycarbonate resin in the presence of an alkyl ester, an aliphatic alcohol, and a catalyst. In particular, it is disclosed that the aliphatic alcohol is any one selected from the group consisting of methanol, ethanol, butanol, and ethylene glycol. It also discloses that the catalyst is any one selected from the group consisting of alkali metal hydroxides, alkali metal alkoxides, alkali metal carbonates, alkali metal oxides, alkylamines, and pyridines. It also discloses that the decomposition temperature is 150°C or lower.

[0009] Meanwhile, although research is also being conducted into the decomposition of polyurethane materials, the majority of the decomposition occurs under high temperature conditions of 100°C or higher. Patent Document 5 discloses a method for decomposing waste urethane resin, filled with a uniformly dispersed reinforcing material, into monomers using a decomposing agent whose main component is alcohol. In particular, the method for decomposing reinforcing-material-filled urethane resin involves carrying out decomposition treatment at a temperature of 240 to 350°C for 1 to 30 minutes using 5 to 20 parts by weight of the decomposing agent per 100 parts by weight of the waste urethane resin.

[0010] In recent years, methods for decomposing polyurethane materials under milder conditions have also been reported. Patent Document 6 discloses a method for decomposing polymer compounds having a specific conjugated structure under mild conditions. Specifically, the decomposition method involves cleaving the main chain of the polymer compound through a conjugate substitution reaction with a nucleophilic agent, which is a compound that generates carboxylate ions, thiolate ions, amide ions, alkoxide ions, or phenolate ions. Furthermore, in the examples, the polymer compound is decomposed by stirring at room temperature for 24 hours in N,N-dimethylformamide solvent or without solvent. However, since the method is limited to polymer compounds having a conjugated structure, it cannot be said to be a general-purpose decomposition method.

[0011] Patent Document 7 discloses a method for producing recycled reinforcing fibers, which includes a step of treating a fiber-reinforced resin material containing reinforcing fibers and a resin component with a treatment liquid containing a solvent, and dissolving at least a portion of the resin component in the treatment liquid. The resin component is not particularly limited, and may be, for example, either a thermosetting resin or a thermoplastic resin, and various resin types are exemplified. It also indicates that acidic and basic substances can be used as catalysts, and that the catalyst content in the treatment solution can be 10% by weight or more and 50% by weight or less. It also indicates that various solvents can be used, and that one type can be used alone or two or more types can be used in combination. Here, "dissolution" is not limited to the direct dissolution of the resin component itself in the treatment solution, but also includes the decomposition of the resin component to generate a reaction product, which then dissolves in the treatment solution. In other words, the purpose is to "dissolve" various types of resins using a strongly acidic or strongly basic treatment solution containing a large amount of catalyst, and the selectivity of the decomposable resin type is not taken into consideration. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-039908 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-131729 [Patent Document 3] Special Publication No. 2020-533395 [Patent Document 4] Japanese Patent Application Publication No. 2023-124421 [Patent Document 5] Japanese Patent Application Publication No. 7-145262 [Patent Document 6] Japanese Patent Application Publication No. 2022-168399 [Patent Document 7] International Publication No. 2022 / 118756 Brochure Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention has been made in view of the above background, and has as its object to provide a method for decomposing an object to be treated that has constituent components containing specific chemical bonds. More specifically, the present invention aims to provide a method for decomposing an object to be treated that has at least one or more chemical moieties. Here, the chemical part has at least one urethane bond, and also includes the case where it has at least one ester bond and / or carbonate bond in addition to at least one urethane bond. Hereinafter, treatment targets having constituent components containing urethane bonds, ester bonds, and carbonate bonds as main components may be abbreviated as "urethane composition," "ester composition," and "carbonate composition," respectively. [Means for solving the problem]

[0014] As shown in the above-mentioned prior art documents, it is known that the decomposition reaction of an ester composition or a carbonate composition can be promoted at a temperature of less than 100°C by combining the specific catalyst, nucleophile, and solvent used in the present invention. Meanwhile, the present inventors conducted extensive research to solve the above problems and found that the decomposition reaction of a urethane composition can also be promoted by further adjusting the combination of a specific catalyst, nucleophile, and solvent. They also found that the decomposition reaction of a urethane composition can be promoted at temperatures lower than those of conventional techniques, particularly at temperatures below 100°C. According to the present invention, the decomposition reaction of a urethane composition can be promoted without relying on a specific structure such as a conjugated structure.

[0015] More specifically, the present inventors discovered that, when the molar fractions of a treatment liquid containing a specific catalyst, a nucleophile, and a solvent are X mol%, Y mol%, and Z mol%, respectively, relative to the total (where X + Y + Z = 100), by adjusting the molar ratio X / Y to be 0.002 or greater and the molar ratio Z / Y to be 0.5 to 40, the decomposition reaction of a treatment target containing a component having at least one urethane bond (excluding those having a conjugated structure) proceeds at temperatures greater than 40°C and less than 100°C, leading to the completion of the present invention. Furthermore, the present inventors discovered that, as a condition for higher catalytic activity, the decomposition reaction proceeds even at temperatures greater than 20°C and less than 40°C by adjusting the composition of the treatment liquid so that the molar ratio X / Y is 0.10 or greater and the molar ratio Z / Y is 0.3 to 40, leading to the completion of the present invention.

[0016] The treatment target (a) in the present invention can be exemplified by various targets as described below, but is preferably a target having at least one or more chemical parts (a1). That is, a target containing a component having a specific chemical bond, such as a urethane bond, an ester bond, or a carbonate bond. More specifically, a target containing a component having at least one or more urethane bonds. Examples include packaging laminate films using urethane adhesives, urethane mats, and urethane sheets. Flexible urethane foams, such as urethane masks, can also be given as examples. As the catalyst (b) in the present invention, various metal salts and nitrogen-containing organic base compounds can be used as described below, and are not particularly limited, but for example, at least one selected from the group consisting of alkali metal hydroxides, alkali metal alkoxides, and nitrogen-containing organic base compounds can be selected for implementation. More specifically, sodium hydroxide, sodium methoxide, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene can be mentioned as examples. The nucleophilic agent (c) in the present invention is not particularly limited and at least one of various agents can be selected as described below, but is preferably a monohydric alcohol having 1 to 8 carbon atoms. More specifically, methanol can be given as an example. The solvent (d) in the present invention is not particularly limited and at least one of various solvents can be selected as described below, but is preferably an aliphatic and / or aromatic hydrocarbon solvent such as n-hexane, cyclohexane, mineral spirits, toluene, xylene, solvent naphtha, etc. More specifically, toluene can be given as an example. [Effects of the Invention]

[0017] According to the present invention, the material to be treated can be subjected to chemical recycling through the decomposition reaction. That is, the decomposition products resulting from the chemical parts contained in the material to be treated can be reused as resources. Therefore, it can also contribute to reducing carbon dioxide emissions. In particular, since the decomposition reaction can proceed at a temperature of less than 100°C, the energy consumption required for the decomposition reaction can be reduced. [Brief explanation of the drawings]

[0018] [Figure 1] 1 shows the results of GPC in Example 1-A of the present invention. [Figure 2] 1 shows the results of GPC for Example EX1-A of the present invention and Comparative Example EX1-A. [Figure 3] 1 shows the results of GPC for Example EX2-A of the present invention. [Figure 4] 1 shows the results of GPC in Reference Example 5 of the present invention.

[0019] In the GPC results, the horizontal axis represents retention time (minutes). Figures 1 to 4 show the results of multiple GPCs with the retention times aligned. DETAILED DESCRIPTION OF THE INVENTION

[0020] In the present invention, the nucleophilic substitution reaction of a specific chemical bond contained in the chemical part of the treatment target (a) can be carried out under conditions containing a catalyst (b), a nucleophile (c), and a solvent (d). The blending ratio of each of these components can be appropriately changed within the range in which the nucleophilic substitution reaction proceeds. Each component used in the present invention will be described in detail below, focusing on the composition of the "treatment liquid" containing the catalyst (b), the nucleophile (c), and the solvent (d). The molar fractions of the catalyst (b), the nucleophile (c), and the solvent (d) in the treatment liquid are X mol%, Y mol%, and Z mol%, respectively (X + Y + Z = 100). The raw materials exemplified in the following description do not limit the configuration of the present invention, and may be modified within the scope of the present invention.

[0021] <Processing target (a)> The treatment object (a) in the present invention is an object having at least one or more chemical parts (a1). Two or more types of the treatment object (a) can be mixed and used. Here, the chemical part (a1) is a component having at least one specific chemical bond (urethane bond, ester bond, carbonate bond). The treatment target (a) in the present invention may take the form of a complex or mixture containing a material part (a2), but the material part (a2) does not inhibit the decomposition reaction of the chemical part (a1).

[0022] The following are examples of the form of a urethane composition, i.e., a composition in which the treatment target (a) of the present invention has a constituent component containing a urethane bond as a main component. Examples include soft urethane foams used in urethane mats, urethane sheets, cushioning materials for chairs and sofas, bed mattresses, carpet backings, etc.; rigid urethane foams used in heat insulation materials, surfboard cores, etc.; thermoplastic urethane elastomers used as components of shoe soles, cable covering materials, and decorative films, etc.; elastic fibers used in synthetic leather, clothing, urethane masks, etc.; and non-foams such as urethane resins used in paints and adhesives.

[0023] Examples of the form of an ester composition, i.e., a composition in which the treatment target (a) of the present invention has a component containing an ester bond as the main component, are given below. Examples include polyester resin products such as polyethylene terephthalate (PET), amorphous polyethylene terephthalate (A-PET), glycol-modified polyethylene terephthalate (G-PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), polyarylate (PAR), polycaprolactone (PCL), polylactic acid (PLA), and polyethylene adipate (PEA); and polyester composites such as food trays, fibers, adhesives, pressure-sensitive adhesives, inks, and coatings. To explain the polyester composite more specifically using the structure of a typical PET bottle as an example, it is composed of a bottle body, a cap, and a label. Here, the bottle body (main component: polyethylene terephthalate) corresponds to the chemical part (a1), and the cap (main component: polyethylene and / or polypropylene) and the label (main component: polystyrene) correspond to the material part (a2). These can be said to be composites in which two or more different components are physically combined without chemical bonding. In recent years, products in which PET bottles are compounded with polyamide resin to impart gas barrier properties have been adopted for wine and other beverages, but the present invention can be applied to such composites that physically contain additional substances. Since the present invention cannot decompose amide bonds, in the above example, polyethylene terephthalate, the raw material of PET bottles, decomposes, while the polyamide resin remains undecomposed. Similarly, examples of composites in which two or more different constituent components are physically combined without chemical bonding include those in which a vapor deposition layer is provided on the surface of a polyester product, and those in which a coloring component is mixed to impart a design. In either case, the ester component can be decomposed by applying the present invention.

[0024] The carbonate composition, i.e., the composition in which the target of treatment (a) of the present invention has a component containing a carbonate bond as a main component, is exemplified below. Examples include construction materials; transparent vehicle components such as automobile window glass, headlight covers, and motorcycle windshields; eyeglass lenses; optical recording media such as optical disks; and resins for paints and adhesives.

[0025] Although the above examples have been given, there are no particular limitations on the shape or form of the object to be treated (a) in the present invention. For example, it can be in the form of a lump, fiber, film, pellet, etc. However, in order to efficiently proceed with the decomposition reaction of the object to be treated (a), it is necessary to allow the treatment liquid containing the catalyst (b), nucleophile (c), and solvent (d) used in the present invention to sufficiently interact with the object to be treated (a). To achieve this, it is preferable to process the object to be treated (a) to increase its surface area. It is also possible to use it without processing, but this will require a longer treatment time and consume more energy. It is also preferable to suppress the influence of impurities on the decomposition reaction, and it is therefore preferable to wash and dry the treatment object (a) before use.

[0026] <Chemical Part (a1)> The chemical part (a1) in the present invention is a component having at least one specific chemical bond (urethane bond, ester bond, carbonate bond). Therefore, components that do not contain the specific chemical bond but have other chemical bonds, such as ether bonds, amide bonds, imide bonds, urea bonds, azo bonds, carbon-carbon bonds, carbon-hydrogen bonds, carbon-halogen bonds, silicon-silicon bonds, etc., are not decomposed under the reaction conditions of the present invention and are therefore not included in the chemical part (a1). However, if a molecule contains the specific chemical bond, it is included in the chemical part (a1) even if other chemical bonds coexist in the same molecule. On the other hand, the material part (a2) is a component that does not contain the specific chemical bond. In the case of acrylic resins, polyvinyl acetate, partially saponified polyvinyl alcohol, etc., the main chain skeleton is not cleaved under the reaction conditions of the present invention, but the ester bonds in the side chain skeleton undergo transesterification, and therefore, these are included in the chemical part (a1).

[0027] To give a specific example of a resin composition used in a packaging laminate adhesive, a polyurethane composition consisting of a polyol composition and a polyisocyanate composition is generally used as the resin composition. Various compositions such as polyester polyol, polyether polyol, and polycarbonate polyol are used as the polyol composition depending on the application of the laminate film. That is, resin compositions such as polyester polyurethane, polyether polyurethane, and polycarbonate polyurethane are used as the adhesive. The adhesive may be water-based, solvent-based, or solventless, and may be one-component or multi-component. The adhesive layer may be formed by any of room temperature curing, heat curing, moisture curing, oxidative polymerization curing, and active energy ray curing.

[0028] When a PET film is included as a constituent film of a laminate film, the PET film corresponds to the chemical part (a1). Also, when an ink layer in a laminate film is formed containing any of a urethane bond, an ester bond, and a carbonate bond, the ink layer corresponds to the chemical part (a1). On the other hand, nylon films, aluminum foils, vapor-deposited layers, etc. are not subject to the decomposition reaction under the reaction conditions of the present invention, and therefore do not fall under the category of the chemical part (a1).

[0029] <Material Part (a2)> In the present invention, the material part (a2) of the treatment target (a) is a component that does not undergo a decomposition reaction under the reaction conditions of the present invention. More specifically, it is a component that does not have a urethane bond, an ester bond, or a carbonate bond. That is, the material part (a2) is a component that does not inhibit the decomposition reaction of the chemical part (a1). Furthermore, the material part (a2) is a component whose composition is not chemically changed by the solvent (d).

[0030] Examples of the material part (a2) include polyolefin components such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), biaxially oriented polypropylene (OPP), and solid polypropylene (CPP); metal components such as aluminum foil (AL); nylon (NY) components; cellulose components; polyphenylsulfide (PPS) components; polyimide (PI) components; vinyl chloride-based components; and fluororesin-based components such as PTFE. Polystyrene (PS) components can also be used. These components may be colored. Furthermore, mineral components such as sodium chloride may be mixed in.

[0031] <Catalyst (b)> As the catalyst (b) of the present invention, metal salts and nitrogen-containing organic basic compounds can be suitably used. These catalysts can be used alone or in combination of two or more.

[0032] Examples of metal salts that can be used include hydroxides, carbonates, fatty acid salts, and alkoxides of alkali metals; hydroxides, carbonates, fatty acid salts, alkoxides, and oxides of alkaline earth metals; and hydroxides, carbonates, fatty acid salts, and alkoxides of transition metals. It is particularly preferable to use hydroxides and alkoxides of alkali metals. These catalysts can be used alone or in combination of two or more.

[0033] Examples of alkali metal hydroxides include lithium hydroxide, sodium hydroxide, and potassium hydroxide. Of these, sodium hydroxide is particularly preferred.

[0034] Examples of alkali metal alkoxides include lithium methoxide, lithium ethoxide, lithium tert-butoxide, sodium methoxide, sodium ethoxide, sodium tert-butoxide, potassium methoxide, potassium ethoxide, and potassium tert-butoxide. Of these, it is particularly preferable to use sodium methoxide.

[0035] Examples of nitrogen-containing organic base compounds include trimethylamine, triethylamine, tributylamine, pyrazole, imidazole, N-methylimidazole, benzimidazole, N-methylbenzimidazole, triazoles, benzotriazole, pyridine, quinoline, isoquinoline, triazines, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 1,8-azabicyclo[5.4.0]undec-7-ene (DBU), and 1,3-dimesitylimidazol-2-ylidene. Among these, TBD is particularly preferred.

[0036] <Nucleophile (c)> As the nucleophilic agent (c) of the present invention, an alcohol can be used. Alternatively, an amine can be used. Among these, an alcohol having 1 to 8 carbon atoms is preferred. A monohydric alcohol having 1 to 8 carbon atoms is more preferred. The nucleophilic agent (c) is characterized by generating an anion upon proton abstraction by the catalyst (b) and performing a nucleophilic attack on a urethane bond, an ester bond, or a carbonate bond, and is distinguished from the solvent (d) described below.

[0037] Examples of monohydric alcohols having 1 to 8 carbon atoms include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol (n-butanol), 2-butanol, tert-butanol, 2-ethylhexanol, and benzyl alcohol. Also usable are glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, butylene glycol monomethyl ether, and butylene glycol monobutyl ether. These may be used alone or in combination of two or more. Among these, primary alcohols are preferred, and methanol is particularly preferred.

[0038] Examples of polyhydric alcohols having 1 to 8 carbon atoms include dihydric alcohols such as 1,2-ethanediol (ethylene glycol), 1,2-propanediol (propylene glycol), 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,2-propanediol, 1,2-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,8-octanediol, 2-ethyl-1,3-hexanediol, 1,2-benzenedimethanol, 1,3-benzenedimethanol, and 1,4-benzenedimethanol; and trihydric or higher alcohols such as trimethylolpropane, glycerin, erythritol, xylitol, and sorbitol.

[0039] The amine is not particularly limited, and monoamines and polyamines can be used. Amino alcohols can also be used. Examples of monoamines include primary amines such as n-butylamine, tert-butylamine, n-octylamine, 2-ethylhexylamine, aminomethylcyclohexane, and benzylamine; secondary amines such as di-n-butylamine, dioctylamine, di(2-ethylhexyl)amine, pyrrolidine, piperidine, and pyrrole; and tertiary amines such as triethylamine, tri-n-butylamine, tri-n-octylamine, and tri-2-ethylhexylamine. Examples of polyamines include ethylenediamine, 1,4-diaminobutane, 1,6-diaminohexane, 1,8-diaminooctane, 1,3-bisaminomethylcyclohexane, 1,4-bisaminomethylcyclohexane, 4-aminopiperidine, isophoronediamine, p-phenylenediamine, 2,4-tolylenediamine, 4,4'-diaminodiphenylmethane, diethylenetriamine, N,N'-dimethylethylenediamine, N,N'-dimethyl-1,2-diaminobutane, N,N'-dimethyl-1,4-diaminobutane, and piperazine. Examples of amino alcohols include aminoethanol, aminoethylethanolamine, dimethylaminoethanol, N,N-diethylethanolamine, N,N-dimethylethanolamine, N-ethyldiethanolamine, triethanolamine, and the like.

[0040] <Solvent (d)> The solvent (d) of the present invention can be appropriately selected as long as it does not inhibit the decomposition reaction, and examples thereof include aliphatic and / or aromatic hydrocarbon solvents such as n-hexane, cyclohexane, mineral spirits, toluene, xylene, and solvent naphtha; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; ester solvents such as ethyl acetate, n-butyl acetate, isobutyl acetate, and ethylene glycol monomethyl ether acetate; carbonate solvents such as dimethyl carbonate and ethyl methyl carbonate; ether solvents such as dioxane, diethyl ether, and tetrahydrofuran; amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; chlorine-containing solvents such as dichloromethane and trichloroethylene; sulfur-containing solvents such as dimethyl sulfoxide; and nitrogen-containing solvents such as acetonitrile and benzonitrile. These may be used alone or in combination of two or more. However, the use of alcohol-based or glycol ether-based solvents as the solvent (d) is excluded. For reasons described below, it is preferable to use an aliphatic and / or aromatic hydrocarbon solvent, and it is particularly preferable to use cyclohexane, toluene, or xylene.

[0041] The solvent (d) may be distilled and reused. However, in order to reduce the energy consumption required for the distillation operation, the boiling point of the solvent (d) is preferably 200°C or lower, more preferably 150°C or lower, and even more preferably 120°C or lower. However, if the boiling point of the solvent (d) is 40°C or lower, the reaction temperature cannot be increased, resulting in a longer reaction time. Also, the catalyst (b) is more likely to be deactivated, making it necessary to increase the amount of the catalyst (b) added.

[0042] The nucleophilic substitution reaction in the present invention is believed to be initiated by an anion generated by proton abstraction from the nucleophile (c) by the catalyst (b). That is, the amount of the catalyst (b) added contributes to the catalytic activity of the nucleophilic substitution reaction, and it is important to adjust the molar ratio of the catalyst (b) to the nucleophile (c). Specifically, the molar ratio X / Y of the catalyst (b) to the nucleophile (c) in the treatment liquid is preferably 0.002 or more, more preferably 0.01 or more, and even more preferably 0.10 or more. By setting the molar ratio within this range, the decomposition of the urethane composition can be achieved at temperatures below 100°C. Note that, when the decomposition of the urethane composition is to proceed in a low temperature range of 20°C or more to 40°C or less, it is necessary to further increase the catalytic activity, and the molar ratio X / Y is preferably 0.10 or more, and more preferably 0.20 or more. The amount of catalyst (b) added can be varied as appropriate depending on the size and shape of the object to be treated (a) and the reaction temperature. However, adding a large amount of catalyst (b) is undesirable because it increases costs. Furthermore, since the basicity of the treatment solution increases depending on the amount of catalyst (b) added, for example, if the material part (a2) contains aluminum, there is a risk of aluminum being deteriorated, which is undesirable from the viewpoint of material recycling. The molar ratio X / Y is preferably 1.0 or less, and more preferably 0.50 or less. On the other hand, adding a small amount of catalyst (b) may result in insufficient decomposition reaction due to deactivation.

[0043] In order to reduce the activation energy required for the nucleophilic substitution reaction in the present invention, it is preferable to use an aprotic solvent as the solvent (d). Although solvents with low polarity can be used, non-polar solvents such as n-hexane are thought to have poor compatibility with the anion generated by the proton abstraction of the nucleophile (c) by the catalyst (b), resulting in a decrease in catalytic activity. Since the nucleophile (c) can also function as a protic polar solvent, it is important to adjust the molar ratio of the solvent (d) to the nucleophile (c). Specifically, the molar ratio Z / Y of the solvent (d) to the nucleophile (c) in the treatment solution is preferably 0.5 to 40, and more preferably 1.0 to 30. Under conditions of high catalytic activity (the molar ratio X / Y of the catalyst (b) to the nucleophile (c) is 0.10 or more), the molar ratio Z / Y is preferably 0.3 to 40, more preferably 0.5 to 40, and even more preferably 1.0 to 30. Within this range, the amount of the solvent (d) added can be adjusted appropriately depending on the size and shape of the object to be treated (a). It can also be adjusted appropriately depending on the reaction apparatus. The contact area of ​​the object to be treated (a) with the solvent (d) is increased by processing it to an appropriate size. However, if the amount of the solvent (d) added is small, the contact with the catalyst (b) and the nucleophile (c) becomes insufficient, making it difficult for the decomposition reaction to proceed. If the amount of nucleophile (c) added is small, the decomposition reaction can be resumed by adding more nucleophile (c).

[0044] <Other ingredients (e)> In addition to the above (a) to (d), other components such as a desiccant and a component that is not involved in the decomposition reaction may be included. These do not limit the configuration of the present invention, and may be added as appropriate within the scope of the present invention.

[0045] <Desiccant> Desiccants include physical desiccants and chemical desiccants, which can be used alone or in combination of two or more.

[0046] Physical desiccants include those that utilize the increased water and / or moisture transport path due to the matrix structure inside the desiccant, and those that utilize physical interactions such as adsorption of water and / or moisture with the desiccant.Specific examples include silica gel, molecular sieves, zeolites, and activated carbon.

[0047] Chemical desiccants include those that adsorb moisture and / or humidity through chemical reactions. Specific examples include metal oxides such as calcium oxide, barium oxide, and magnesium oxide; metal salts such as sodium sulfate, calcium sulfate, magnesium sulfate, calcium chloride, magnesium chloride, sodium carbonate, and potassium carbonate; diphosphorus pentoxide; silane compounds such as vinyltrimethoxysilane, dimethyldimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, diphenyldimethoxysilane, and phenyltrimethoxysilane; and orthoester compounds such as methyl orthoformate, ethyl orthoformate, methyl orthoacetate, and ethyl orthoacetate.

[0048] The decomposition reaction of the present invention preferably proceeds at a temperature of 20° C. or higher but lower than 100° C., preferably 30° C. or higher but lower than 90° C., and more preferably 40° C. or higher but lower than 80° C. Although the decomposition reaction proceeds at temperatures below 20° C., the catalytic activity is insufficient. Furthermore, although the decomposition reaction proceeds at temperatures above 100° C., this is not preferable from the viewpoint of energy costs.

[0049] The decomposition reaction of the present invention can be carried out under normal pressure or reduced pressure, but may also be carried out under increased pressure. There is no particular limitation on the reaction time, but it can be, for example, 0.5 to 24 hours.

[0050] Examples of the mixing method include stirring with a ceramic rotor, mechanical stirring with a stirring blade, and mixing by circulation. [Example]

[0051] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0052] In the examples shown below, the following raw materials were used unless otherwise specified. <Processing target (a)> PET pellets: Commercially available products were used. Polycarbonate plate (PC plate): Mitsubishi Engineering Plastics Corporation, Yubilon IMR05 The following films were used as the material part (a2). Nylon (NY) film: Unitika Ltd., Emblem ONBC-RT, thickness 15 μm PE film: RM Tocello Co., Ltd., TUX-FC-S, thickness 60 μm Aluminum foil (AL): Toyo Aluminum Co., Ltd., thickness 20 μm

[0053] <Catalyst (b)> Sodium methoxide: Fujifilm Wako Pure Chemical Industries, Ltd., Wako First Grade Lithium methoxide: manufactured by Tokyo Chemical Industry Co., Ltd. Potassium methoxide: Fujifilm Wako Pure Chemical Industries, Ltd. Sodium tert-methoxide: manufactured by Tokyo Chemical Industry Co., Ltd. Sodium hydroxide: Kanto Chemical Co., Ltd., Grade 1 Potassium hydroxide: Kanto Chemical Co., Ltd. Calcium hydroxide: Special grade manufactured by Kanto Chemical Co., Ltd. 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD): manufactured by Tokyo Chemical Industry Co., Ltd. Sulfuric acid: Kishida Chemical Co., Ltd., special grade

[0054] <Nucleophile (c)> Methanol: Fujifilm Wako Pure Chemical Industries, Ltd., ultra-dehydrated grade Ethanol: Fujifilm Wako Pure Chemical Industries, Ltd., ultra-dehydrated grade Isopropyl alcohol: Fujifilm Wako Pure Chemical Industries, Ltd., ultra-dehydrated grade n-Butanol: Fujifilm Wako Pure Chemical Industries, Ltd., special grade t-Butanol: Fujifilm Wako Pure Chemical Industries, Ltd., special grade Benzyl alcohol: manufactured by Tokyo Chemical Industry Co., Ltd. Ethylene glycol monobutyl ether: Tokyo Chemical Industry Co., Ltd. · 1,4-Butanediol: Manufactured by Tokyo Chemical Industry Co., Ltd.

[0055] <Solvent (d)> · Toluene: Manufactured by Kanto Chemical Co., Inc., special grade · Xylene: Manufactured by FUJIFILM Wako Pure Chemical Corporation, special grade · Methylcyclohexane: Manufactured by Tokyo Chemical Industry Co., Ltd. · n-Hexane: Manufactured by Kanto Chemical Co., Inc., special grade · Dimethyl carbonate: Manufactured by Kanto Chemical Co., Inc., extra special grade [[ID=· 15]] · MEK: Manufactured by FUJIFILM Wako Pure Chemical Corporation · Dichloromethane: Manufactured by Kanto Chemical Co., Inc., special grade · Ethyl acetate: Manufactured by Kanto Chemical Co., Inc., special grade · Acetonitrile: Manufactured by FUJIFILM Wako Pure Chemical Corporation, special grade · N,N-Dimethylformamide (DMF): Manufactured by Kanto Chemical Co., Inc., special grade

[0056] <Filter> · Stainless steel with a mesh size of 0.5 mm

[0057] [Evaluation method] <GPC (Gel Permeation Chromatography)> The weight average molecular weight in the present invention is a value in terms of polystyrene by GPC. For example, the measurement conditions in the following examples are as follows: the temperature of the column (KF-805L × 2 manufactured by Showa Denko K.K.) is 35 °C, tetrahydrofuran (THF) is used as the eluent, the flow rate is 1.0 mL / min, the detection is performed with a RI detector (differential refractometer), and the sample concentration is 0.3 mass%.

[0058] <FT-IR (Fourier Transform Infrared Spectroscopy)> FT-IR was performed using IRPrestige-21 manufactured by Shimadzu Corporation.

[0059] <Evaluation criteria for the degree of decomposition of the urethane composition> Unless otherwise specified, the degree of decomposition of the urethane composition was determined from the results of GPC. Specifically, the degree to which the urethane bond had undergone a nucleophilic substitution reaction was determined from the change in molecular weight of the treatment object (a). Note that the decomposition of ester compositions and carbonate compositions that do not contain urethane bonds is shown as a reference example. From the perspective of promoting the recycling of urethane compositions, it is preferable that the degree of decomposition is rated as △ or higher, and ○△ or higher is more preferable. A rating of △ or higher can be said to indicate that the resin has lost its original performance and is in a recyclable state, so a degree of decomposition greater than this was considered acceptable. ○: Peaks derived from components before decomposition have disappeared, and peaks derived from constituent components have been detected. ○△: Peaks derived from the components before decomposition have almost disappeared, and peaks derived from the constituent components are detected. △: The peaks derived from the components before decomposition have become slightly sharper, but remain. △×: Peaks derived from constituent components are detected, but do not change significantly from the peaks derived from the components before decomposition. ×: No change from the peaks derived from the components before decomposition.

[0060] <Preliminary Consideration> As a preliminary study, in order to simplify the consideration of the decomposition reaction, the reaction conditions of the present invention were applied to the main component of the following adhesive composition. [Main component of polyester polyurethane adhesive (hereinafter referred to as AD1)] Rockbond J RU-40 (manufactured by Rock Paint Co., Ltd.) was used, which contains urethane bonds and ester bonds. [Main ingredient of polyether polyurethane adhesive (hereinafter abbreviated as AD2)] It was synthesized using the following manufacturing method. It contains urethane bonds and ether bonds, but does not contain ester bonds or carbonate bonds.

[0061] [AD2 main ingredient manufacturing method] Three polyalkylene glycols with different molecular weights, aromatic bifunctional isocyanate monomers, and a tin catalyst were added to a reaction vessel equipped with a nitrogen inlet tube, a stirrer, and a condenser. The mixture was allowed to react for 4 hours at an internal temperature of 80°C while stirring. FT-IR confirmed that the absorption of the isocyanate group had completely disappeared, yielding the main component of AD2. The weight-average molecular weight was 3,800. The composition of the main agent of AD2 can be schematically represented as in Chemical Formula 1 below. That is, it contains urethane bonds and ether bonds as chemical bonds other than carbon-carbon bonds (in the formula, R represents an aliphatic or aromatic hydrocarbon. R1, R2, and R3 represent aliphatic hydrocarbons. m1, m2, and m3 represent integers of 1 or greater. n1, n2, and n3 represent integers of 0 or 1, one of which is 0 and the remaining two are 1. For example, when n3=0, n1=n2=1, which indicates that no ether chain resulting from R3 is included).

[0062] [ka]

[0063] [Example 1-A] To a reaction vessel containing the main component of AD2 (6.00 parts by weight) as the treatment target (a), sodium methoxide (0.33 parts by weight) as the catalyst (b) and methanol (9.73 parts by weight) as the nucleophile (c) were added. Toluene (83.94 parts by weight) was added as the solvent (d), and the mixture was stirred at 65°C for 2 hours. The molar ratio of the catalyst (b), nucleophile (c), and solvent (d) was 0.02:1:3. After the reaction was completed, the reaction solution was filtered, but no filtration residue was obtained. The filtrate was dried and the resulting components were analyzed by GPC. As shown in Figure 1, the peaks derived from the components before decomposition disappeared, and peaks derived from the constituent components were detected. The retention times of these peaks almost coincided with the peak retention times of the polyalkylene glycols that were the raw materials for the main component of AD2 (the degree of decomposition was evaluated as ○). From the above, it was determined that the urethane bond in the main component of AD2 had undergone a nucleophilic substitution reaction, i.e., the main component of AD2 had decomposed. Hereinafter, when an alkali metal alkoxide is used as the catalyst (b), the example will be suffixed with "A."

[0064] [Example 1-B] The molar ratio of the catalyst (b), the nucleophile (c), and the solvent (d) was fixed, and the main component of AD2 was treated in the same manner as in Example 1-A, unless otherwise specified, except that the catalyst (b) was changed to sodium hydroxide based on Example 1-A. After the reaction was completed, the reaction solution was filtered, but no filtration residue was obtained. The filtrate was dried and the obtained components were analyzed by GPC, and the results were the same as those in Figure 1, and it was determined that the main component of AD2 had decomposed (the degree of decomposition was evaluated as ○). Hereinafter, when a hydroxide is used as the catalyst (b), the example will be suffixed with "B."

[0065] [Examples 1-C and 1-C'] In Example 1-C, the molar ratio of the catalyst (b), the nucleophile (c), and the solvent (d) was fixed, and the main component of AD2 was treated in the same manner as in Example 1-A, unless otherwise specified, except that the catalyst (b) was changed to TBD based on Example 1-A. After the reaction was completed, the reaction solution was filtered, but no residue was obtained. The filtrate was dried and the resulting components were analyzed by GPC. The peaks derived from the components before decomposition were slightly sharper, but still remained (the degree of decomposition was evaluated as fair). On the other hand, in Example 1-C', when the amount of catalyst (b) added was increased to five times the amount, the degree of decomposition was improved to an excellent rating.

[0066] [Reference examples 1-A, 2-A, 1-B, 2-B] In Reference Example 1-A, the molar ratio of the catalyst (b), the nucleophile (c), and the solvent (d) was fixed, and the treatment object (a) was changed to PET pellets based on Example 1-A, and the treatment was carried out in the same manner as in Example 1-A unless otherwise specified. After the reaction was complete, the reaction solution was filtered, but no filter residue was obtained. The filtrate was washed with water, and the organic layer was dried to obtain a solid. When the resulting components were analyzed by FT-IR, the peaks due to polyethylene terephthalate disappeared, and peaks due to dimethyl terephthalate were observed. Therefore, it was determined that the ester bonds in the polyethylene terephthalate had undergone alcoholysis, i.e., the PET pellets had decomposed. In Reference Example 2-A, when the reaction temperature was changed to 20°C based on Reference Example 1-A, the peak due to polyethylene terephthalate disappeared and a peak due to dimethyl terephthalate was observed, as in Reference Example 1-A. Therefore, it was determined that the PET pellets were decomposed even at 20°C. In Reference Examples 1-B and 2-B, the treatments were carried out in the same manner as in Examples 1-A and 2-A, respectively, except that the catalyst (b) was changed to sodium hydroxide, based on Reference Examples 1-A and 2-A, unless otherwise specified. It was determined that the PET pellets were decomposed when sodium hydroxide was used as catalyst (b), just as when sodium methoxide was used.

[0067] [Example EX1-A, Comparative Example EX1-A] In Example EX1-A, the molar ratio of the catalyst (b), the nucleophile (c), and the solvent (d) was fixed, and the treatment object (a) was changed to the main agent AD1 based on Example 1-A, except that the treatment was carried out in the same manner as in Example 1-A unless otherwise specified. After the reaction was completed, the reaction solution was filtered, but no filtration residue was obtained. The filtrate was dried and the resulting components were analyzed by GPC. As shown in Figure 2, the peaks due to the main component of AD1 disappeared, and peaks due to the constituent components were detected (the degree of decomposition was evaluated as ○). In addition, based on the results of Reference Examples 1-A and 2-A, it was determined that the ester bond contained in the main component of AD1 had also decomposed. On the other hand, in Comparative Example EX1-A, when the reaction temperature was changed to 20°C based on Example EX1-A, the peak due to the main component AD1 disappeared, but as shown in Figure 2, a broader peak remained in the higher molecular weight region than in Example EX1-A. Considering the results of Reference Examples 1-A and 2-A, it is thought that at 20°C, the urethane bond did not undergo nucleophilic substitution reaction, and only the ester bond did. In other words, it can be said that the nucleophilic attack on the urethane bond by the nucleophile (c) proceeds less easily than the nucleophilic attack on the ester bond.

[0068] [Example EX1-B, Comparative Example EX1-B] In Example EX1-B and Comparative Example EX1-B, the treatments were the same as in Example EX1-A and Comparative Example EX1-A, respectively, except that catalyst (b) was changed to sodium hydroxide, unless otherwise specified. When sodium hydroxide was used as catalyst (b), urethane bonds and ester bonds decomposed at 65°C, just as when sodium methoxide was used, but at 20°C, only ester bonds decomposed and urethane bonds did not decompose.

[0069] [Table 1]

[0070] Table 1 lists the weight fraction and molar fraction of each component. Unless otherwise specified, the following discussion will be based on Example 1, using the AD2 base agent (6.00 parts by weight) and treatment solution (94.00 parts by weight) as the treatment target (a), and will focus on the molar ratios of the catalyst (b), nucleophile (c), and solvent (d) that make up the treatment solution. The cases will also be divided according to the type of catalyst (b), with Pattern A representing sodium methoxide and Pattern B representing sodium hydroxide.

[0071] <1. Comparison of catalyst (b)> Based on the results of the above preliminary investigation, each component was investigated. First, the types of catalyst (b) were compared.

[0072] [Examples 1-A-2 to 1-A-4] Unless otherwise specified, the main agent of AD2 was treated in the same manner as in Example 1-A, except that the catalyst (b) was changed to a metal alkoxide of an alkali metal shown in Table 2. The degree of decomposition was evaluated as ○ in all cases.

[0073] [Examples 1-B-2 to 1-B-3] In Example 1-B-2, the main component of AD2 was treated in the same manner as in Example 1-B, except that the catalyst (b) was changed to potassium hydroxide, unless otherwise specified. The degree of decomposition was evaluated as ○. On the other hand, in Example 1-B-3, the main agent of AD2 was treated in the same manner as in Example 1-B, except that the catalyst (b) was changed to calcium hydroxide. The degree of decomposition was evaluated as fair. This is thought to be due to the fact that when an alkaline earth metal hydroxide is used as the catalyst (b), the catalytic activity is lower than when an alkali metal hydroxide is used.

[0074] [Comparative Example 1] Unless otherwise specified, the main component of AD2 was treated in the same manner as in Example 1-A, except that the catalyst (b) was changed to sulfuric acid. The degree of decomposition was evaluated as △×. In Example 1-A, it is believed that the nucleophilic substitution reaction of the urethane bond proceeds starting from proton abstraction of the nucleophile (c) by sodium methoxide. On the other hand, when sulfuric acid is used as a catalyst, it is believed that such proton abstraction is less likely to occur, making it difficult for the nucleophilic substitution reaction of the urethane bond to proceed.

[0075] Comparative Example 2 Unless otherwise specified, the main component of AD2 was treated in the same manner as in Example 1-A, except that the catalyst (b) was not added. The degree of decomposition was evaluated as x. It is believed that when the catalyst (b) was not added, proton abstraction of the nucleophile did not occur, and therefore the nucleophilic substitution reaction of the urethane bond did not proceed.

[0076] [Table 2]

[0077] <2. Comparison of nucleophiles (c)> Next, the types of nucleophiles (c) were compared.

[0078] [Examples 2 to 8] Unless otherwise specified, the main component of AD2 was treated in the same manner as in Example 1, except that the nucleophilic agent (c) was changed to the alcohols shown in Table 3. The degree of decomposition was evaluated as fair or better in all cases.

[0079] Comparative Example 3 Unless otherwise specified, the main component of AD2 was treated in the same manner as in Example 1, except that the nucleophile (c) was not added. The degree of decomposition in Comparative Example 3-A was evaluated as △×. Although methanol was not added as the nucleophile (c), it is believed that the sodium methoxide used as the catalyst (b) decomposed due to moisture in the air to produce methanol, which acted as the nucleophile (c). However, the amount of methanol that could be produced was so small that it was insufficient to proceed with the nucleophilic substitution reaction of the urethane bond. On the other hand, the degree of decomposition in Comparative Example 3-B was rated as ×. It is believed that the nucleophilic substitution reaction of the urethane bond did not proceed because methanol cannot be produced from sodium hydroxide used as catalyst (b).

[0080] [Table 3]

[0081] <3. Comparison of solvents (d)> Next, the types of solvent (d) were compared.

[0082] [Examples 9 to 17] The main component of AD2 was treated in the same manner as in Example 1, unless otherwise specified, except that the solvent (d) was changed to the solvent shown in Table 4. The degree of decomposition was evaluated as ○ in all cases except when n-hexane was used. This is thought to be due to the low polarity of n-hexane, which has poor compatibility with the anion generated by proton abstraction of the nucleophile (c) by the catalyst (b). Dichloromethane has a low boiling point and can only reach 40°C when heated, so the degree of decomposition was rated as fair under the same conditions as in Example 1. However, when the amount of catalyst was increased five times, the results were improved to a rating of good, as shown in Table 4.

[0083] Comparative Example 4 The main component of AD2 was treated in the same manner as in Example 1, except that the solvent (d) was not added. The degree of decomposition was evaluated as △×. This is thought to be because methanol also acts as a protic solvent, stabilizing the anion generated when the catalyst (b) abstracts the proton of the nucleophile (c), increasing the activation energy required to proceed with the nucleophilic substitution reaction of the urethane bond.

[0084] [Table 4]

[0085] <4. Comparison of reaction temperatures> Next, the reaction temperature was compared.

[0086] [Comparative Examples 5 to 6] As shown in Table 5, the main agent of AD2 was treated in the same manner as in Example 1, except that the reaction temperature was changed to 20°C or 40°C, unless otherwise specified. The degree of decomposition was evaluated as x in all cases. It is believed that the catalytic activity could not be sufficiently increased in the low temperature range of 20°C to 40°C.

[0087] [Examples 18 to 21] Unless otherwise specified, the main component of AD2 was treated in the same manner as in Example 1, except that the reaction temperature was changed to 20°C or 40°C and the amount of catalyst (b) added was changed as shown in Table 5. The degree of decomposition was evaluated as good or better in all cases. This is thought to be because increasing the amount of catalyst (b) added provided sufficient catalytic activity to allow the nucleophilic substitution reaction of the urethane bond to proceed even at a low reaction temperature.

[0088] [Table 5]

[0089] <5. Comparison of the composition of processing solutions> Next, the compositions of the treatment solutions were compared.

[0090] [Examples 22 to 28, Comparative Example 7] The main component of AD2 was treated in the same manner as in Example 1, unless otherwise specified, except that the molar ratio of the catalyst (b) and the nucleophile (c) was fixed and the molar ratio of the solvent (d) was changed as shown in Table 6. The degree of decomposition clearly differed depending on the molar ratio Z / Y of the solvent (d) and the nucleophile (c). It is believed that the nucleophilic substitution reaction of the urethane bond proceeds starting from an anion generated when the catalyst (b) abstracts a proton from the nucleophile (c). However, when the molar ratio Z / Y was large, i.e., when the amount of the solvent (d) was high relative to the amount of the nucleophile (c), the degree of decomposition was thought to worsen due to the influence of a decrease in the concentration of the anion. On the other hand, when the molar ratio Z / Y is small, that is, when the amount of the solvent (d) is small relative to the amount of the nucleophile (c), the proportion of the nucleophile (c) acting as a protic solvent becomes relatively large, which is thought to have increased the activation energy required for the nucleophilic substitution reaction of the urethane bond, thereby worsening the degree of decomposition.

[0091] [Table 6]

[0092] [Examples 29 to 34, Comparative Examples 8 to 10] The molar ratio of the catalyst (b) was fixed, and the total molar ratio of the nucleophile (c) and the solvent (d) was fixed. The main component of AD2 was treated in the same manner as in Example 1, unless otherwise specified, except that the molar ratios of the nucleophile (c) and the solvent (d) were changed as shown in Table 7. The degree of decomposition clearly differed depending on the molar ratio Z / Y of the solvent (d) and the nucleophile (c). This is thought to be due to the same reasons discussed in Examples 22 to 28 and Comparative Example 7.

[0093] [Table 7]

[0094] [Examples 35 to 38, Comparative Example 11] The AD2 base material was treated in the same manner as in Example 1, unless otherwise indicated, except that the molar ratio of the nucleophile (c) and the solvent (d) was fixed and the molar ratio of the catalyst (b) was changed as shown in Table 8. At 65°C, even when the amount of catalyst was 1 / 10 of that in Example 1, the degree of decomposition was rated as good (Example 35). In Example 28 shown in Table 6, the degree of decomposition was rated as fair, but when the amount of catalyst was increased five times, the degree of decomposition improved to a rating of good (Example 36). As shown in Comparative Example 11, when the molar ratio Z / Y of the solvent (d) to the nucleophilic agent (c) was 0.3, the degree of decomposition was evaluated as △×. On the other hand, when the amount of catalyst was increased to 5 or 10 times the amount, the degree of decomposition was improved to △ or ○ (Examples 37 and 38).

[0095] [Table 8]

[0096] As shown in the results in Tables 2 to 8, a treatment solution containing a specific catalyst (b), a nucleophile (c), and a solvent (d) was prepared for a treatment object (a) having at least one urethane bond, and the molar ratio of the catalyst (b) and the solvent (d) to the nucleophile (c) was set within a specific range, thereby enabling the decomposition of the urethane bond.

[0097] <6. Comparison of processed object (a)> Finally, a comparative study was conducted on treatment target (a).

[0098] [Examples EX2 to 5, Comparative Examples EX2 to 7] Unless otherwise specified, the same procedure as in Example 1 was carried out except that the treatment object (a) was changed to that shown in Table 9. However, since the bulkiness of each treatment object (a) was not necessarily the same, the composition of the treatment liquid was fixed (the molar ratio of catalyst (b), nucleophile (c), and solvent (d) was 0.02:1:3), and the addition ratio of the treatment liquid to the treatment object (a) was changed as appropriate.

[0099] In Example EX2, decomposition was attempted using a cured film of AD1. Rockbond J RU-40 (Rock Paint Co., Ltd.), the base agent of AD1, was mixed with Rockbond J H-4 (Rock Paint Co., Ltd.), the curing agent of AD1, and a film was formed on a glass plate using an applicator, followed by drying at 40°C for 3 days. After drying, the cured film was peeled off from the glass plate and used. After the reaction was completed, the reaction solution was filtered, but no filtration residue was obtained. The filtrate was dried and the resulting components were analyzed by GPC. As shown in Figure 3, the peaks derived from the components before decomposition disappeared, and peaks derived from the constituent components were detected. From the above, it was determined that decomposition had also progressed in the cured film of AD1 (the degree of decomposition was evaluated as ○). Furthermore, when a laminated film for packaging consisting of OPP / AD1 / CPP was used for the study, the constituent films, OPP and CPP, could be separated and recovered by decomposing AD1, with no residual AD1 remaining in these films.

[0100] In Examples EX3 to EX5, decomposition was attempted using a commercially available urethane mat, urethane sheet, and urethane mask. These urethane foams did not dissolve in the solvent before decomposition, making it impossible to measure their molecular weight. However, when the reaction solution was filtered after the reaction was completed, no filter residue was obtained. This means that these urethane foams did not simply dissolve in the toluene used as solvent (d), but rather that the decomposition products dissolved in the toluene. Furthermore, when the filtrate was dried and analyzed by FT-IR, it was confirmed that a slight peak due to the urethane bond remained. In both cases, the degree of decomposition was rated as fair, although this was a simple evaluation.

[0101] In Comparative Examples EX2 and EX3, decomposition was attempted using an acrylic resin (Kuraray Co., Ltd., COMOGRASS) and a PVA resin (Wako Co., Ltd., PVA super absorbent cloth), respectively. In studies using these, a viscous substance was obtained after the reaction was completed. When the reaction solution was dried and the resulting components were analyzed by GPC, the peaks attributable to the resin before the reaction were reduced, but the peaks attributable to high molecular weight compounds remained, indicating that complete decomposition had not occurred. The ester bonds in the resin side chains were transesterified with methanol, resulting in a slight reduction in molecular weight, but the main chain structure was not cleaved, so it is thought that a viscous substance remained. In Comparative Example EX4, decomposition was attempted using EVA resin (multipurpose EVA sheet manufactured by Trusco Nakayama Corporation), but almost no change was observed.

[0102] In Comparative Examples EX5 and EX6, decomposition was attempted using a melamine decorative board (C-6000BG, manufactured by Aica Kogyo Co., Ltd.) and a phenolic resin (FL102, manufactured by Futamura Chemical Co., Ltd.), respectively. After the reaction was completed, the reaction solution was filtered to obtain a melamine decorative board and a phenolic resin, both of which were unchanged from their pre-reaction states. Therefore, under the reaction conditions of the present invention, the decomposition reaction could not proceed for only the material part (a2), i.e., the component not having the specific chemical bond (urethane bond, ester bond, carbonate bond).

[0103] In Comparative Example EX7, decomposition was attempted using a styrene resin (Kyoei PS, manufactured by Kyoei Resin Co., Ltd.). After the reaction was completed, the reaction solution was filtered, but no residue was obtained. However, when the components remaining after the reaction solution was dried were analyzed by GPC, no decrease in molecular weight was observed. In other words, the styrene resin simply dissolved in the toluene used as the solvent (d), and no decomposition of the styrene resin occurred.

[0104] [Table 9]

[0105] [Examples EX6 to EX11, Reference Examples 3 to 5] Unless otherwise specified, the same procedures as in Example 1 were carried out except that the treatment object (a) and material part (a2) shown in Table 10 were used.

[0106] In Example EX6, the treatment object (a) was a mixture of the main agent of AD2 and PET pellets. After the reaction was completed, the reaction solution was filtered, but no filtration residue was obtained. As in Example 1 and Reference Example 1, the mixture was analyzed by GPC and FT-IR, and it was determined that decomposition had also progressed in the mixed system of the urethane composition and the ester composition (the degree of decomposition was evaluated as ○).

[0107] In Example EX7, the treatment object (a): a mixture of the main agent of AD2 and the material part (a2): a nylon film. After the reaction was completed, the reaction solution was filtered, and only a nylon film was obtained. The nylon film obtained was not altered. Meanwhile, the filtrate was dried and the resulting components were analyzed by GPC, and it was determined that the main component of AD2 had decomposed, as in Example 1 (the degree of decomposition was evaluated as ○). In Reference Examples 3 and 4, decomposition was attempted using only nylon film. In Reference Example 3, the reaction time was extended to 4 hours, and in Reference Example 4, the reaction temperature was raised to 110°C, but no change was observed in the nylon film. Therefore, it is considered that decomposition of amide bonds does not proceed under the reaction conditions of the present invention. Furthermore, even in a mixed system of the target (a) and the material part (a2), it can be said that the material part (a2) does not inhibit the decomposition of urethane bonds contained in the target (a).

[0108] In Example EX8, the treatment object (a) was a mixture of the main agent AD2 and nylon-composite PET. Here, the nylon-composite PET was a composite of PET pellets and Nylon-MXD6 (a crystalline polyamide obtained by polycondensation reaction of metaxylenediamine and adipic acid, manufactured by Mitsubishi Gas Chemical Company, Inc.) in a weight ratio of 95:5. The reaction solution was filtered, and the remaining unreacted nylon-composite PET was removed from the resulting residue. FT-IR analysis of the residue detected amide bonds originating from nylon-MXD6. Therefore, it was confirmed that decomposition also proceeded in the composite system of the treatment target (a) and the material part (a2) (the degree of decomposition was evaluated as ○).

[0109] In Reference Example 5, decomposition was attempted using only a polycarbonate plate (PC plate). After the reaction was completed, the reaction solution was filtered, but no filter residue was obtained. The filtrate was dried and the resulting components were analyzed by GPC. As shown in Figure 4, the peaks derived from the components before decomposition disappeared, and peaks derived from the constituent components were detected. The retention times of these peaks almost coincided with the peak retention times of bisphenol A, the raw material for PC boards. From the above, it was determined that the carbonate bonds of the PC boards underwent a nucleophilic substitution reaction with methanol, and decomposition proceeded all the way to the raw material bisphenol A. In Example EX9, the treatment object (a) was a mixture of the main agent of AD2 and PC board. After the reaction was completed, the reaction solution was filtered, but no filtration residue was obtained. As in Example EX6, decomposition of the urethane bond also progressed in the mixed system of the urethane composition and the carbonate composition (the degree of decomposition was evaluated as ○).

[0110] In Examples EX10 to EX11, the treatment object (a): a mixture of the main agent of AD2 and the material part (a2): a PE film or aluminum foil was used. After the reaction was completed, the reaction solution was filtered, and only a PE film and an aluminum foil were obtained. These films were not altered. Meanwhile, the filtrate was dried and the resulting components were analyzed by GPC. As in Example 1, it was determined that the main component of AD2 had decomposed (both degrees of decomposition were evaluated as ○).

[0111] [Table 10]

Claims

1. A method for decomposing a urethane bond contained in a treatment target (a) using a treatment liquid, comprising: The treatment target (a) contains a component having at least one urethane bond (excluding those having a conjugated structure), the treatment liquid contains a catalyst (b), a nucleophilic agent (c), and a solvent (d); When the molar fractions of the catalyst (b), the nucleophilic agent (c), and the solvent (d) relative to the total amount are X mol %, Y mol %, and Z mol %, respectively (where X + Y + Z = 100), the molar ratio X / Y is 0.002 or more, and the molar ratio Z / Y is 0.5 or more and 40 or less, characterized in that it proceeds at a temperature greater than 40°C and less than 100°C; How to break down urethane bonds.

2. A method for decomposing a urethane bond contained in a treatment target (a) using a treatment liquid, comprising: The treatment target (a) contains a component having at least one urethane bond (excluding those having a conjugated structure), the treatment liquid contains a catalyst (b), a nucleophilic agent (c), and a solvent (d); When the molar fractions of the catalyst (b), the nucleophilic agent (c), and the solvent (d) relative to the total amount are X mol %, Y mol %, and Z mol %, respectively (where X + Y + Z = 100), the molar ratio X / Y is 0.10 or more, and the molar ratio Z / Y is 0.3 or more and 40 or less, The reaction proceeds at a temperature of 20°C or higher and lower than 100°C. How to break down urethane bonds.

3. The treatment target (a) contains a component having at least one urethane bond (excluding those having a conjugated structure), Furthermore, the composition is characterized in that it contains a component having at least one ester bond and / or carbonate bond. The method for decomposing a urethane bond according to claim 1 or 2.

4. the catalyst (b) is at least one selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal alkoxides, and nitrogen-containing organic basic compounds; The method for decomposing a urethane bond according to claim 1 or 2.

5. the catalyst (b) is at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium methoxide, sodium methoxide, potassium methoxide, sodium tert-butoxide, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene; The method for decomposing a urethane bond according to claim 4.

6. The nucleophilic agent (c) is a monohydric alcohol having 1 to 8 carbon atoms. The method for decomposing a urethane bond according to claim 1 or 2.

7. The nucleophile (c) is methanol. The method for decomposing a urethane bond according to claim 6.

8. The solvent (d) contains an aliphatic and / or aromatic hydrocarbon solvent. The method for decomposing a urethane bond according to claim 1 or 2.

9. The solvent (d) contains at least one selected from the group consisting of cyclohexane, toluene, and xylene. The method for decomposing a urethane bond according to claim 7.

10. The molar ratio X / Y is 0.01 or more, and the molar ratio Z / Y is 1.0 or more and 30 or less. The method for decomposing a urethane bond according to claim 1.

11. The molar ratio X / Y is 0.20 or more, and the molar ratio Z / Y is 0.5 or more and 40 or less. The method for decomposing a urethane bond according to claim 2.

12. The treatment object (a) is a packaging laminate film using a urethane adhesive, The method for decomposing a urethane bond according to claim 1 or 2.

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