Method for decomposing cured product of curable resin composition, method for recovering filler, and method for recovering decomposed product

Abstract

Disclosed is a method for decomposing a cured product of a curable resin composition, the method including decomposing the cured product of the curable resin composition, which includes a compound having a thioethylamine structure, with use of a decomposition liquid that includes a peroxide. Also disclosed are: a method for recovering a filler, the method using the above-described method for decomposing the cured product of the curable resin composition; and a method for recovering a decomposed product.

Description

Method for decomposing a cured product of a curable resin composition, method for recovering a filler, and method for recovering a decomposed product

[0001] The present invention relates to a method for decomposing a cured product of a curable resin composition, a method for recovering a filler, and a method for recovering a decomposed product.

[0002] Curable compounds such as epoxy resins are widely used in paints, adhesives, and, when combined with fillers (carbon fiber, glass fiber, etc.), in automobile and wind turbine parts, etc. Cured products of curable resin compositions containing such fillers are difficult to decompose and remove, making it difficult to recover the fillers.

[0003] Pyrolysis and dissolution methods are known as techniques for recovering fillers from cured products of curable resin compositions containing fillers (see Patent Document 1). However, the pyrolysis method raises concerns about the deterioration of filler quality and increased environmental impact due to high-temperature treatment. On the other hand, although the dissolution method uses milder conditions than the pyrolysis method, lowering the treatment temperature to reduce environmental impact tends to increase the treatment time.

[0004] Japanese Patent Application Laid-Open No. 2022-015366

[0005] Under these circumstances, there is a demand for a technique that can decompose a cured product of a curable resin composition in a short time even at a low temperature. The present invention aims to solve this problem and to provide a method for decomposing a cured product of a curable resin composition that can decompose a cured product of a curable resin composition in a short time even at a lower temperature than conventional methods, a method for recovering a filler, and a method for recovering a decomposed product.

[0006] In light of the above-mentioned problems, the present inventors have conducted research and found that the above-mentioned problems can be solved by decomposing a cured product of a curable resin composition containing a compound having a thioethylamine structure using a decomposition liquid containing a peroxide. Specifically, the above-mentioned problems have been solved by the following means. <1> A method for decomposing a cured product of a curable resin composition, which includes decomposing a cured product of a curable resin composition containing a compound having a thioethylamine structure using a decomposition liquid containing a peroxide. <2> The decomposition method according to <1>, wherein the thioethylamine structure is represented by formula (1). (In formula (1), -X- represents -S-, -S(=O)-, -S(=O) ２ -, -SS-, -SS(=O)-, -SS(=O) ２ -, -S(=O)-S(=O)-, -S(=O)-S(=O) ２ - or -S(=O) ２ -S(=O) ２ -, * indicates the bonding position with other sites, R １ are each independently a substituent, and R ２is a hydrogen atom or a substituent. m1 is an integer of 0 to 2.) <3> The decomposition method according to <1> or <2>, wherein the compound having a thioethylamine structure is a curing agent for a curable resin. <4> The decomposition method according to <1> or <2>, wherein the compound having a thioethylamine structure is a curable resin. <5> The decomposition method according to <1> or <2>, wherein the compound having a thioethylamine structure is a curable resin and a curing agent for the curable resin. <6> The decomposition method according to any one of <1> to <5>, wherein the peroxide contained in the decomposition liquid includes hydrogen peroxide. <7> A method for recovering a filler, comprising decomposing a cured product of a curable resin composition containing a compound having a thioethylamine structure and a filler using a decomposition liquid containing a peroxide, and recovering the filler. <8> The method for recovering a filler according to <7>, wherein the cured product of the curable resin composition is decomposed by the method according to any one of <1> to <6>. <9> The method for recovering a filler according to <7> or <8>, wherein the filler comprises a reinforcing fiber. <10> A method for recovering a decomposition product, comprising: decomposing a cured product of a curable resin composition containing a compound having a thioethylamine structure using a decomposition liquid containing a peroxide and a solvent, adding a poor solvent, and recovering a solid decomposition product by filtration. <11> The method for recovering a decomposition product according to <10>, wherein the amount of solvent in the decomposition liquid is reduced and then the poor solvent is added. <12> The method for recovering a decomposition product according to <10> or <11>, wherein the decomposition of the cured product of the curable resin composition is carried out by the method described in any one of <1> to <6>. <13> A method for recovering a decomposition product, comprising: decomposing a cured product of a curable resin composition containing a compound having a thioethylamine structure and a filler using a decomposition liquid containing a peroxide and a solvent, recovering the filler, adding a poor solvent, and recovering a solid decomposition product by filtration. <14> The method for recovering a decomposition product according to <13>, wherein the amount of solvent in the decomposition liquid is reduced and then the poor solvent is added. <15> The method for recovering decomposition products according to <13> or <14>, wherein the cured product of the curable resin composition is decomposed by the method according to any one of <1> to <6>.

[0007] The present invention makes it possible to provide a method for decomposing a cured product of a curable resin composition, a method for recovering a filler, and a method for recovering a decomposed product, which can decompose the cured product of a curable resin composition at a lower temperature in a shorter time than conventional methods.

[0008] Figure 1 shows an image of a compound having a thioethylamine structure as an amine-based curing agent for a curable resin. Figure 2 shows an image of a compound having a thioethylamine structure as a thiol-based curing agent for a curable resin. Figure 3 shows an image of a compound having a thioethylamine structure as a curable resin.

[0009] Hereinafter, a detailed description will be given of an embodiment of the present invention (hereinafter simply referred to as "the present embodiment"). Note that the following present embodiment is an example for explaining the present invention, and the present invention is not limited to this embodiment. In this specification, the term "to" is used to mean that the numerical values ​​before and after it are included as lower and upper limits. In this specification, various physical property values ​​and characteristic values ​​are those at 23°C unless otherwise specified. In the description of a group (atomic group), a notation that does not indicate substituted or unsubstituted encompasses both a group (atomic group) that has no substituent and a group (atomic group) that has a substituent. For example, the term "alkyl group" encompasses not only an alkyl group that has no substituent (unsubstituted alkyl group) but also an alkyl group that has a substituent (substituted alkyl group). In this specification, when a notation that does not indicate substituted or unsubstituted is used, unsubstituted is preferred. Examples of the substituent in this specification are preferably a halogen atom, a cyano group, a nitro group, a hydroxy group, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, a heterocyclic group, a heterocyclicoxy group, an alkenyl group, an alkylsulfanyl group, an arylsulfanyl group, an acyl group, or an amino group, more preferably a halogen atom, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an alkenyl group, or an acyl group, even more preferably an alkyl group, an aryl group, an aryloxy group, or an alkenyl group, and still more preferably an alkyl group. The formula weight of these substituents is preferably 15 or more, and preferably 200 or less. The formula weight is, for example, the formula weight of a methyl group (-CH３ ) is 15. These substituents may further have a substituent, but it is preferable that they have no substituent.

[0010] In this specification, the term "process" does not only refer to an independent process, but also includes processes that cannot be clearly distinguished from other processes as long as the process achieves its intended effect. If the measurement methods, etc. described in the standards shown in this specification vary from year to year, they will be based on the standards as of January 1, 2023, unless otherwise specified.

[0011] Here, the resin solid content means components other than the filler and solvent contained in the curable resin composition, and includes the curable resin, the curing agent, and, as necessary, a flame retardant, an ultraviolet absorber, an antioxidant, a silane coupling agent, etc.

[0012] The method for decomposing a cured product according to the present embodiment involves decomposing a cured product of a curable resin composition containing a compound having a thioethylamine structure using a decomposition liquid containing a peroxide. This configuration allows the cured product of the curable resin composition to be decomposed at a lower temperature in a shorter time than conventional methods. As a result, the filler can be recovered while maintaining its quality.

[0013] The cured product of this embodiment has a thioethylamine structure. In the thioethylamine structure shown below, the wavy line portion is bonded to another portion. By adding peroxide to the cured product having a thioethylamine structure, the S portion becomes S(=O). ２ (However, as shown in the formula (1) below, S(=O) ２(In some cases, N becomes NO, and when NO becomes NOH, the C-N bond between the N and the adjacent carbon atom is presumably cleaved. Therefore, it is presumed that the cured product can be easily decomposed. In particular, since the above-mentioned cured product contains a bond in its structure that is easily cleaved by peroxide, it can be decomposed more easily at lower temperatures than conventional products. Furthermore, the decomposition time can be shortened. Furthermore, since the above-mentioned cured product contains a bond in its structure that is easily cleaved by peroxide, it is also valuable in that it can be decomposed without the use of acid or the like. That is, when decomposition is performed with acid, the cured product, especially the filler, may be damaged by the acid. However, the decomposition method of this embodiment can decompose the cured product without the use of acid, which is beneficial when recovering the filler. Furthermore, neutralization of the decomposed product is not required, as is the case with decomposition using acid. Note that a single thioethylamine structure may be contained in one molecule of a compound having a thioethylamine structure, or two or more thioethylamine structures may be contained.

[0014] The curable resin composition according to the present embodiment contains a compound having a thioethylamine structure. The thioethylamine structure is preferably represented by formula (1). (In formula (1), -X- represents -S-, -S(=O)-, -S(=O) ２ -, -SS-, -SS(=O)-, -SS(=O) ２ -, -S(=O)-S(=O)-, -S(=O)-S(=O) ２ - or -S(=O) ２ -S(=O) ２ -, * indicates the bonding position with other sites, R １ are each independently a substituent, and R ２ is a hydrogen atom or a substituent. m1 is an integer of 0 to 2.

[0015] In formula (1), -X- represents -S-, -S(=O)-, -S(=O) ２ -, -SS-, -SS(=O)-, -SS(=O) ２ -, -S(=O)-S(=O)-, -S(=O)-S(=O) ２ - or -S(=O) ２ -S(=O) ２-, -S-, -S(=O)- or -S(=O) ２ In formula (1), R is preferably —, and more preferably —S—. １ are each independently a substituent, preferably a halogen atom, a cyano group, a nitro group, a hydroxy group, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, a heterocyclic group, a heterocyclicoxy group, an alkenyl group, an alkylsulfanyl group, an arylsulfanyl group, an acyl group, or an amino group, more preferably a halogen atom, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an alkenyl group, or an acyl group, even more preferably an alkyl group, an aryl group, an aryloxy group, or an alkenyl group, still more preferably an alkyl group, even more preferably a linear alkyl group having 1 to 5 carbon atoms, and still more preferably a methyl group. The formula weight of the substituent is preferably 15 or more, and preferably 200 or less, preferably 100 or less, more preferably 50 or less, and even more preferably 30 or less.

[0016] In formula (1), R ２is a hydrogen atom or a substituent, preferably a hydrogen atom, a halogen atom, a cyano group, a nitro group, a hydroxy group, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, a heterocyclic group, a heterocyclicoxy group, an alkenyl group, an alkylsulfanyl group, an arylsulfanyl group, an acyl group, or an amino group; more preferably a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an alkenyl group, or an acyl group; even more preferably a hydrogen atom, an alkyl group, an aryl group, an aryloxy group, or an alkenyl group; even more preferably a hydrogen atom or an alkyl group; even more preferably a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms; even more preferably a hydrogen atom or a methyl group; and particularly preferably a hydrogen atom. The formula weight of the substituent is preferably 15 or more, and preferably 200 or less, preferably 100 or less, more preferably 50 or less, and even more preferably 30 or less. In formula (1), m1 is an integer of 0 to 2, preferably 0 or 1, and more preferably 0.

[0017] The compound having a thioethylamine structure may be a curing agent for a curable resin, a curable resin, or both a curable resin and a curing agent for a curable resin. The curable resin is preferably a thermosetting resin.

[0018] When a compound having a thioethylamine structure is a curing agent for a curable resin, the curing agent is not particularly limited as long as it has a thioethylamine structure and is a compound that cures the curable resin (which may or may not have a thioethylamine structure), but it is preferable to include a curing agent that has a thioethylamine structure and has an amino group and / or a thiol group.

[0019] When a compound having a thioethylamine structure is used as a curing agent for a curable resin, its molecular weight is preferably 100 or more, more preferably 105 or more, even more preferably 110 or more, still more preferably 115 or more, and even more preferably 120 or more. By setting the molecular weight at or above the lower limit, handling properties tend to be further improved. Furthermore, the molecular weight of the curing agent is preferably 500 or less, more preferably 450 or less, even more preferably 400 or less, still more preferably 350 or less, and even more preferably 300 or less. By setting the molecular weight at or below the upper limit, the fluidity of the curable resin composition and the thermal properties of the cured product tend to be improved.

[0020] In a first embodiment of the compound having a thioethylamine structure, the compound having a thioethylamine structure is a curing agent (amine-based curing agent) having an amino group. The first embodiment will be described with reference to FIG. 1 . FIG. 1 illustrates an image of a case in which the compound having a thioethylamine structure is an amine-based curing agent, where 1 indicates the curable resin curing agent (amine-based curing agent), 2 indicates the curable resin (epoxy resin), and 3 indicates the partial structure of the cured product. As shown in FIG. 1 (1), the curing agent of the curable resin has a thioethylamine structure. Curing agent 1 reacts with the epoxy group of curable resin 2 to form cured product 3. It is presumed that immersing such a cured product in a decomposition solution containing peroxide breaks the C-N bond in the thioethylamine structure (dotted line portion in FIG. 1), decomposing cured product 3. When the curable resin composition contains a filler, the filler can also be easily recovered.

[0021] The amine-based curing agent is more preferably an amine-based curing agent represented by formula (2). (In formula (2), R １ are each independently a substituent, and R ３ is a hydrocarbon group which may have a substituent, and R ３The hydrocarbon may contain at least one group of group A consisting of —O—, —S—, —NH—, —C(═O)—, —C(═O)O— and —C(═O)NH—, and the atom adjacent to the group of group A is a carbon atom. m1 is an integer of 0 to 2.

[0022] In formula (2), R １ and m1 are R in formula (1), respectively. １ and m1 have the same meanings and preferred ranges as well. ３ is a hydrocarbon group which may have a substituent, and R ３ The hydrocarbon in R may contain at least one group of Group A consisting of -O-, -S-, -NH-, -C(=O)-, -C(=O)O-, and -C(=O)NH-, and the atom adjacent to the group of Group A is a carbon atom. Preferably, the atom adjacent to the group of Group A is a carbon atom, and at least one of the carbon atoms is bonded to a hydrogen atom or an alkyl group having 1 to 3 carbon atoms (preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom), and R ３ The number of atoms connecting the adjacent N and S is 1 to 18.

[0023] The R ３ The hydrocarbon group as R may preferably be a non-aromatic aliphatic group which may be substituted, more preferably a linear or branched aliphatic group which may be substituted, and even more preferably a linear aliphatic group which is not substituted. The number of carbon atoms in the aliphatic group is preferably 1 or more, more preferably 2 or more, and is preferably 18 or less, more preferably 16 or less, even more preferably 14 or less, and may further be 12 or less, 10 or less, 8 or less, 6 or less, or 4 or less. In this embodiment, R may further be ３ is two or more -CH ２ -, or two or more -CH ２ and at least one group selected from group A consisting of —O—, —S—, —NH—, —C(═O)—, and —C(═O)O—, and two or more —CH ２-, or two or more -CH ２ A group consisting of a combination of - and -S- is more preferred, and two or more -CH ２ More preferably, the group is a group consisting of two or more —CH ２ The group consisting of - is preferably 18 or less, more preferably 10 or less, even more preferably 6 or less, and even more preferably 4 or less -CH ２ - is a group consisting of

[0024] The atom adjacent to the group A is a carbon atom, and at least one of the carbon atoms is bonded to a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. ３ When the non-aromatic chain hydrocarbon contains —O—, at least —C(R) ２ -O-C(R) ２ It has a structure of R- (R is a hydrogen atom or a substituent, and at least one of R is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms). ３ The number of atoms connecting the adjacent N and S is preferably 1 to 18. For example, in the case of the following compound, R ３ The number of atoms connecting the adjacent N and S is 8.

[0025] R ３ The number of atoms connecting adjacent N and S is preferably 2 or more, and is preferably 16 or less, more preferably 14 or less, and even more preferably 12 or less, 10 or less, 8 or less, 6 or less, or 4 or less. By making the number equal to or less than the upper limit, the fluidity of the curable resin composition and the thermal properties of the cured product tend to be improved.

[0026] In a first embodiment of the compound having a thioethylamine structure, R ３ is R ３ Preferably, the atoms connecting the adjacent N and S are all carbon atoms, and R ３ It is more preferable that R is composed of only carbon atoms and hydrogen atoms. ３The phrase "both atoms connecting adjacent N and S are carbon atoms" means that, for example, as shown below, the atom connecting N and S may be a carbon atom, and another group (a fluorine atom in the following example) may be bonded to the carbon atom connecting N and S.

[0027] Below, R ３ One side is NH of formula (2) ２ and the other is bonded to S. n is an integer from 0 to 17. n1 and n2 are each an integer from 1 to 16, and the sum of n1 and n2 is an integer from 2 to 17. n3 is an integer from 1 to 8.

[0028]

[0029] Specific examples of the compound having a thioethylamine structure represented by formula (1) used in this embodiment are shown below, but it goes without saying that this embodiment is not limited to these.

[0030] The amine-based curing agent represented by formula (2) used in the first embodiment of the compound having a thioethylamine structure is produced by a known method.

[0031] In a second embodiment of the compound having a thioethylamine structure, the compound having a thioethylamine structure is a curing agent having a thiol group (thiol-based curing agent). The second embodiment of the compound having a thioethylamine structure will be described with reference to FIG. 2. FIG. 2 shows an image of a case in which the compound having a thioethylamine structure is a thiol-based curing agent, in which 11 indicates the curing agent (thiol-based curing agent) for the curable resin, 21 indicates the curable resin (epoxy resin), and 31 indicates a partial structure of the cured product. As shown by 11 in FIG. 2, the thiol-based curing agent 11 has a thioethylamine structure. The thiol-based curing agent 11 reacts with the epoxy group of the curable resin 21 to form a cured product 31. It is presumed that immersing such a cured product in a decomposition solution containing peroxide breaks the C-N bond in the thioethylamine structure (the dotted line in FIG. 2), causing the cured product 31 to decompose.

[0032] The type of the thiol-based curing agent is not particularly limited, but it is more preferable that the thiol-based curing agent be a thiol-based curing agent represented by formula (3). (In formula (3), R １ is a substituent, and R ２ is a hydrogen atom or a substituent, and R ３ is a hydrocarbon group which may have a substituent, and R ３ The hydrocarbon may contain at least one group of group A consisting of —O—, —S—, —NH—, —C(═O)—, —C(═O)O— and —C(═O)NH—, and the atom adjacent to the group of group A is a carbon atom. m1 is an integer of 0 to 2.

[0033] In formula (3), R １ , R ２ and m1 are R in formula (1), respectively. １ , R ２ or m1, and the preferred range is also the same. ３ is R in formula (2). ３ The same applies to the preferred range.

[0034] The thiol-based curing agent represented by the above formula (3) is produced by a known method.

[0035] A third embodiment of the compound having a thioethylamine structure is a curing agent (aminothiol-based curing agent) in which the compound having a thioethylamine structure has an amino group and a thiol group.

[0036] The aminothiol curing agent is not particularly limited in type, but is preferably a curing agent represented by formula (4). (In formula (4), R １ is a substituent, and R ２ is a hydrogen atom or a substituent, and R ３ is a non-aromatic hydrocarbon group which may have a substituent, and R ３ The hydrocarbon may contain at least one group of group A consisting of —O—, —S—, —NH—, —C(═O)—, —C(═O)O— and —C(═O)NH—, and the atom adjacent to the group of group A is a carbon atom. m1 is an integer of 0 to 2.

[0037] In formula (4), R １ , R ２ and m1 are R in formula (1), respectively. １ , R ２ or m1, and the preferred range is also the same. ３ is R in formula (2). ３ The same applies to the preferred range.

[0038] The aminothiol curing agent represented by formula (4) is produced by a known method.

[0039] In a fourth embodiment of the compound having a thioethylamine structure, the compound having a thioethylamine structure is a curable resin. The fourth embodiment of the compound having a thioethylamine structure will be described with reference to FIG. 3 . FIG. 3 illustrates an image of a case where a compound having a thioethylamine structure is a curable resin, in which 12 indicates a curing agent for the curable resin, 22 indicates a curable resin (epoxy resin) that is a compound having a thioethylamine structure, and 32 indicates a partial structure of the cured product. As indicated by 22 in FIG. 3 , the curable resin 22 has a thioethylamine structure. In this embodiment, the curing agent 12 reacts with the epoxy group of the curable resin 22 to form a cured product 32. It is presumed that immersing such a cured product in a decomposition solution containing peroxide breaks the C-N bond in the thioethylamine structure (dotted line in FIG. 3 ), causing the cured product 32 to decompose.

[0040] The curable resin used in the fourth embodiment of the compound having a thioethylamine structure is not particularly limited as long as it is a resin having a thioethylamine structure. Examples include epoxy compounds, oxetane compounds, unsaturated polyesters, polyimides, and polyurethanes, with epoxy compounds being preferred. The epoxy compound is not particularly limited as long as it is a compound having one or more epoxy groups per molecule, and a wide variety of known epoxy compounds can be used. The number of epoxy groups in the epoxy compound is preferably 2 to 12, more preferably 2 to 6, even more preferably 2 to 4, even more preferably 2 or 3, and even more preferably 2. The number of thioethylamine structures per molecule of the curable resin is preferably 1 or more (preferably 12 or less, more preferably 10 or less).

[0041] As described above, in the curable resin composition of the present embodiment, the compound having a thioethylamine structure may be a curing agent for a curable resin, may be a curable resin, or may be both a curable resin and a curing agent for a curable resin.

[0042] When the curable resin does not have a thioethylamine structure, there is no particular restriction as long as it is a curable resin whose curing is accelerated by a curing agent having a thioethylamine structure, but the curable resin is preferably a thermosetting resin, more preferably an epoxy compound, an oxetane compound, or an unsaturated polyester, and even more preferably an epoxy compound. The epoxy compound is not particularly limited as long as it is a compound having one or more epoxy groups (preferably 2 to 12, more preferably 2 to 6, even more preferably 2 to 4, still more preferably 2 or 3, and even more preferably 2) per molecule, and a wide variety of known epoxy compounds can be used. Examples of the epoxy compound include bisphenol-based epoxy compounds (bisphenol A-type epoxy compounds, bisphenol E-type epoxy compounds, bisphenol F-type epoxy compounds, bisphenol S-type epoxy compounds, etc.), phenol novolac-type epoxy compounds, bisphenol A novolac-type epoxy compounds, glycidyl ester-type epoxy compounds, aralkyl novolac-type epoxy compounds, biphenyl aralkyl-type epoxy compounds, naphthylene ether-type epoxy compounds, cresol novolac-type epoxy compounds, multifunctional phenol-type epoxy compounds, naphthalene-type epoxy compounds, anthracene-type epoxy compounds, naphthalene skeleton-modified novolac-type epoxy compounds, phenol aralkyl-type epoxy compounds, naphthol aralkyl-type epoxy compounds, dicyclopentadiene-type epoxy compounds, biphenyl-type epoxy compounds, alicyclic epoxy compounds, polyol-type epoxy compounds, phosphorus-containing epoxy compounds, glycidyl amines, glycidyl esters, compounds in which the double bond of butadiene or the like has been epoxidized, and compounds obtained by reacting hydroxyl-containing silicone compounds with epichlorohydrin. Preferably, the epoxy compound is a bisphenol-based epoxy compound. Further, with regard to the epoxy compound, the descriptions in paragraphs 0076 to 0077 of JP-A-2014-227427, the descriptions in paragraphs 0036 to 0039 of JP-A-2018-83905, and the descriptions in paragraphs 0032 to 0035 of JP-A-2018-135433 can be referred to, the contents of which are incorporated herein by reference.

[0043] The content of the curable resin (a curable resin not having a thioethylamine structure and a curable resin having a thioethylamine structure) in the curable resin composition in this embodiment is preferably 60 parts by weight or more, more preferably 65 parts by weight or more, even more preferably 70 parts by weight or more, even more preferably 75 parts by weight or more, and even more preferably 80 parts by weight or more, relative to 100 parts by weight of the resin solids in the curable resin composition. By setting the content at or above the lower limit, the thermal properties of the cured product tend to be improved. Furthermore, the upper limit of the content of the curable resin is preferably 99.5 parts by weight or less, more preferably 99 parts by weight or less, even more preferably 97 parts by weight or less, even more preferably 91 parts by weight or less, and even more preferably 90 parts by weight or less, relative to 100 parts by weight of the resin solids in the curable resin composition. By setting the content at or below the upper limit, the thermal properties of the cured product tend to be improved. The curable resin composition in this embodiment may contain only one type of curable resin, or may contain two or more types of curable resin. When two or more types are contained, the total amount is preferably within the above range.

[0044] On the other hand, when the compound having a thioethylamine structure is the curable resin, the curing agent may or may not have a thioethylamine structure. The type of curing agent not having a thioethylamine structure is not particularly limited as long as it can cure the curable resin having a thioethylamine structure. Examples of the curing agent include amine-based curing agents not having a thioethylamine structure, guanidine-based curing agents, acid anhydride-based curing agents (such as carboxylic acid anhydrides), phenol-based curing agents (such as novolac resins), thiol-based curing agents not having a thioethylamine structure, Lewis acid amine complex-based curing agents, onium salt-based curing agents, imidazole-based curing agents, and urea-based curing agents.

[0045] Examples of amine-based curing agents that do not have a thioethylamine structure include aliphatic amine-based curing agents such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, diethylaminopropylamine, hexamethylenediamine, methylpentamethylenediamine, trimethylhexamethylenediamine, guanidine, tetramethylguanidine, and oleylamine; menthenediamine, isophoronediamine, norbornanediamine, piperidine, N,N'-dimethylpiperazine, N-aminoethylpiperazine, Ramiron C-260 manufactured by BASF, and Araldit manufactured by CIBA. Alicyclic amine-based curing agents such as HY-964, Rohm and Haas Company's menthenediamine, 1,2-diaminocyclohexane, diaminodicyclohexylmethane, bis(4-amino-3-methylcyclohexyl)methane, bis(4-aminocyclohexyl)methane, polycyclohexylpolyamine, and 1,8-diazabicyclo[5,4,0]undecene-7 (DBU); aromatic amine-based curing agents such as m-xylylenediamine, m-phenylenediamine, 4,4'-diaminodiphenylmethane, and 4,4'-diaminodiphenylsulfone; (CH ３ ) ２ N (CH ２ ) ｎ N (CH ３ ) ２ (wherein n is an integer of 1 to 10), a linear diamine represented by (CH ３ ) ２ -N(CH ２ ) n-CH ３ (wherein n is an integer of 0 to 10), a linear tertiary amine represented by the formula N{(CH ２ ) nCH ３} ３(wherein n is an integer of 1 to 10); aliphatic aromatic amines such as benzyldimethylamine, 2-(dimethylaminomethyl)phenol, and 2,4,6-tris(dimethylaminomethyl)phenol; polyetheramine-based curing agents such as 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5,5]undecane (ATU), morpholine, N-methylmorpholine, polyoxypropylenediamine, polyoxypropylenetriamine, and polyoxyethylenediamine; and hydroxyl group-containing amine-based curing agents such as diethanolamine and triethanolamine, among which aliphatic amine-based curing agents, alicyclic amine-based curing agents, and polyetheramine-based curing agents are preferred, and polyetheramine-based curing agents are more preferred.

[0046] The content of the curing agent (a curing agent having a thioethylamine structure and a curing agent not having a thioethylamine structure) contained in the curable resin composition of this embodiment is preferably 0.5 parts by weight or more, more preferably 1.0 parts by weight or more, even more preferably 3.0 parts by weight or more, even more preferably 9.0 parts by weight or more, and even more preferably 10.0 parts by weight or more, relative to 100 parts by weight of the resin solid content in the curable resin composition. The upper limit of the content of the curing agent contained in the curable resin composition is preferably 40 parts by weight or less, more preferably 35 parts by weight or less, even more preferably 30 parts by weight or less, even more preferably 25 parts by weight or less, and even more preferably 20 parts by weight or less, relative to 100 parts by weight of the resin solid content in the curable resin composition. The curable resin composition of this embodiment may contain only one type of curing agent, or may contain two or more types. When two or more types are contained, the total amount falls within the above range.

[0047] The curable resin composition used in this embodiment may contain a filler. Examples of fillers include fumed silica, precipitated silica, crystalline silica, fused silica, dolomite, anhydrous silicic acid, hydrous silicic acid, carbon black, heavy calcium carbonate, colloidal calcium carbonate, magnesium carbonate, diatomaceous earth, calcined clay, clay, talc, titanium oxide, bentonite, organic bentonite, ferric oxide, aluminum fine powder, flint powder, zinc oxide, activated zinc white, shirasu balloons, glass microballoons, and reinforcing fibers (glass fiber, carbon fiber, etc.). Reinforcing fibers are preferred, and carbon fiber is more preferred. If included, the content of the filler in the curable resin composition used in this embodiment is preferably 1 part by weight or more, more preferably 10 parts by weight or more, and preferably 1,500 parts by weight or less, per 100 parts by weight of the resin solids. The curable resin composition used in this embodiment may contain only one type of filler, or may contain two or more types. When two or more types are included, the total amount is within the above range.

[0048] The curable resin composition used in this embodiment may contain components other than the curable compound and the curing agent, such as a reactive diluent, a non-reactive diluent, a curing accelerator, a plasticizer, a pigment, a dye, a release agent, a toughening agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a fluidizing agent, a leveling agent, an antifoaming agent, a flame retardant, or a thickener.

[0049] In this embodiment, the cured product is formed from the curable resin composition. An example of the cured product is fiber-reinforced plastic (FRP). The cured product is preferably a cured product used in architectural paints, adhesives, automotive parts, aircraft parts, composite materials, printed circuit board materials, insulating impregnation materials for heavy electrical equipment, encapsulants for electronic elements, and the like. Cured products used for the applications described in paragraph 0045 of JP-A No. 2018-83905, paragraph 0053 of JP-A No. 2018-135433, paragraphs 0039 to 0043 of JP-T No. 2016-527384, and paragraph 0048 of JP-A No. 2011-213983 are also preferably used, and the contents of these applications are incorporated herein by reference.

[0050] On the other hand, the method for decomposing a cured product of this embodiment includes decomposing the cured product of the curable resin composition using a decomposition liquid containing a peroxide. The cured product of this embodiment has a thioethylamine structure, so it can be easily decomposed with peroxide. As a result, the filler contained in the cured product can be easily recovered. Examples of peroxides include organic compounds having a peroxide structure (-O-O-) or a percarboxylic acid structure (-C(=O)-O-O-) as a functional group, and inorganic compounds having peroxide ions (O ２ ２－ ) is not particularly specified. The molecular weight of the peroxide is preferably 34 to 500. In this embodiment, the peroxide preferably used is hydrogen peroxide, percarboxylic acid (performic acid, peracetic acid, metachloroperbenzoic acid), methyl ethyl ketone peroxide, benzoyl peroxide, acetone peroxide, diethyl ether, hexamethylene triperoxide diamine, dimethyldioxirane, di-tert-butyl peroxide, benzoyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 1,1'-di-t-butylperoxy-3,3,5-trimethylenecyclohexane, 1,3-di-(t-butylperoxy)-diisopropylbenzene, lithium peroxide, potassium peroxide, sodium peroxide, magnesium peroxide, calcium peroxide, barium peroxide, zinc peroxide, or the like. Furthermore, among these, hydrogen peroxide ultimately decomposes into harmless water and oxygen after the reaction, producing less waste and making it suitable for industrial use. In this embodiment, the decomposition liquid preferably contains 1 to 80 wt % of peroxide, more preferably 10 to 60 wt %. The decomposition method of this embodiment is advantageous in that it can effectively decompose the cured product and recover the filler, even when decomposed using only hydrogen peroxide at low temperatures (for example, 50°C or less, or even 40°C or less) and at normal pressure.

[0051] The decomposition liquid in this embodiment may contain a component other than peroxide. The decomposition liquid in this embodiment may contain at least one selected from the group consisting of a surfactant (preferably a nonionic surfactant or an ionic surfactant), a carboxylic acid (preferably formic acid or acetic acid), a heteropolyacid (preferably tungstophosphoric acid or molybdophosphoric acid), and a heteropolyacid salt (preferably sodium tungstophosphate (metal oxide) or sodium molybdophosphate). In this embodiment, the decomposition liquid may or may not contain a surfactant. If a surfactant is contained, the content thereof is preferably 0% by weight or more, more preferably 0.01% by weight or more, and may even be 1% by weight or more or 5% by weight or more. It is also preferably 30% by weight or less, more preferably 20% by weight or less, and even more preferably 10% by weight or less, and may even be 5% by weight or less, 1% by weight or less, or 0.1% by weight or less. The inclusion of a surfactant tends to improve the decomposition property of the cured product and the solubility of the decomposition product. In this embodiment, when the decomposition liquid contains a carboxylic acid, the content is preferably 1 to 80 wt %, and more preferably 20 to 60 wt %. The inclusion of a carboxylic acid tends to improve the decomposition property of the cured product and the solubility of the decomposition product. In this embodiment, the decomposition liquid may be substantially free of a carboxylic acid. For example, by using a peroxide in combination with a surfactant, the cured product can be dissolved in the decomposition liquid, allowing the filler to be appropriately recovered. In this embodiment, when the decomposition liquid contains a heteropolyacid and / or a heteropolyacid salt, the content is preferably 0.02 wt % or more, more preferably 0.04 wt % or more, and preferably 1 wt % or less, more preferably 0.5 wt % or less, and even more preferably 0.1 wt % or less. The combined use of a peroxide and a heteropolyacid and / or a heteropolyacid salt tends to improve the decomposition property of the cured product.

[0052] Furthermore, the decomposition liquid in this embodiment may or may not contain water. In this embodiment, the water content in the decomposition liquid is preferably 50% by weight or less, and may even be 45% by weight or less, with the lower limit being 0% by weight or more. By setting the water content to 50% by weight or less, the solubility of the decomposition products can be further improved. Furthermore, the decomposition liquid in this embodiment may contain a solvent other than water. The solvent other than water may be an organic solvent or an inorganic solvent, and preferably contains an organic solvent. Examples of organic solvents include hydrocarbon solvents, alcohol solvents, ketone solvents, ester solvents, ether solvents, glycol solvents, glycol ester solvents, glycol ether solvents, amide solvents, sulfoxide solvents, and nitrile solvents. Hydrocarbon solvents, alcohol solvents, amide solvents, and nitrile solvents are preferred, and hydrocarbon solvents and nitrile solvents are more preferred. Examples of hydrocarbon solvents include aromatic hydrocarbon solvents such as benzene, toluene, and m-xylene, and aliphatic hydrocarbon solvents such as ethane, hexane, octane, and heptane, with aromatic hydrocarbon solvents being preferred. Examples of nitrile solvents include acetonitrile, propionitrile, and benzonitrile, with acetonitrile being preferred. The inclusion of a solvent other than water tends to improve the solubility of the decomposition products. In this embodiment, when the decomposition liquid contains a solvent other than water, the content of the solvent other than water is preferably 1 to 90 wt %, and more preferably 10 to 80 wt %.

[0053] These components other than the peroxide may each be contained alone or in combination of two or more.

[0054] In the decomposition method of this embodiment, the decomposition temperature can be set to 150°C or lower, and can further be set to 130°C or lower, 110°C or lower, 100°C or lower, 90°C or lower, 80°C or lower, 70°C or lower, or 65°C or lower. The lower limit of the decomposition temperature is usually 40°C or higher, and may be 45°C or higher, 50°C or higher, 55°C or higher, or 60°C or higher. This embodiment is valuable in that decomposition can proceed effectively without raising the decomposition temperature. In addition, in the decomposition method of this embodiment, the decomposition temperature can be set to be 5°C or higher, and can be 10°C or higher, lower than the glass transition temperature of the cured product. The decomposition temperature refers to the temperature of the decomposition liquid. The glass transition temperature is measured in accordance with ISO 11357-2.

[0055] In the decomposition method of the present embodiment, the decomposition time can be determined as appropriate. For example, when a cured product is cut into a piece 15 mm wide, 15 mm long, and 1 mm thick and immersed in 10 mL of decomposition liquid, the decomposition time can be set to 8 hours or less, and more practically, 1 hour or more.

[0056] In the decomposition method of this embodiment, the pKa of each component contained in the decomposition solution is preferably 0 or higher, more preferably 2 or higher, and even more preferably 3 or higher. There is no particular upper limit, but the pKa is usually 13 or lower. Furthermore, when the decomposition solution contains a carboxylic acid, the pKa thereof is preferably 0 to 5.

[0057] The filler recovery method of this embodiment includes decomposing a cured product of a curable resin composition containing a compound having a thioethylamine structure and a filler using a decomposition liquid containing a peroxide, and recovering the filler. As described above, the cured product can be decomposed at low temperature in a short time, allowing the filler to be effectively recovered. In particular, the decomposition of the cured product in this embodiment is preferably carried out by the above-mentioned method for decomposing a cured product.

[0058] A first embodiment of the decomposition product recovery method of this embodiment includes decomposing a cured product of a curable resin composition containing a compound having a thioethylamine structure using a decomposition liquid containing peroxide and a solvent, adding a poor solvent, and recovering a solid decomposition product by filtration. A second embodiment of the decomposition product recovery method of this embodiment includes decomposing a cured product of a curable resin composition containing a compound having a thioethylamine structure and a filler using a decomposition liquid containing peroxide and a solvent, recovering the filler, adding a poor solvent, and recovering a solid decomposition product by filtration. As a method for recovering the decomposition product, it is preferable to reduce the amount of solvent in the decomposition liquid and then add a poor solvent. By adding a poor solvent, organic solvents (toluene or acetonitrile), water, and peroxides can be removed from the decomposition liquid, making it possible to efficiently recover a solid decomposition product. The poor solvent used in this embodiment is a solvent in which the solid decomposition product does not substantially dissolve. For example, the solubility of the solid decomposition product at 23°C (weight ratio of the solid decomposition product dissolved in 100 g of solvent) is preferably 15 wt% or less, more preferably 10 wt% or less, even more preferably 5 wt% or less, even more preferably 1 wt% or less, even more preferably 0.5 wt% or less, and even more preferably 0.1 wt% or less. Examples of poor solvents include water, alcohols such as methanol and ethanol, aliphatic hydrocarbon solvents such as ethane, hexane, octane, and heptane, and acetone, with water being preferred. Use of such a poor solvent allows the decomposition product to be efficiently precipitated from the solution obtained after decomposition of the cured product. Alternatively, the hydrophilic compound and the solvent of the decomposition solution can be more easily separated. A method for recovering the decomposition product in this embodiment includes, for example, concentrating the solution in which the cured product is dissolved under reduced pressure at 30°C to obtain a concentrate. Water is added to the obtained concentrate to precipitate the decomposition product, and the solid decomposition product is recovered by filtration. Furthermore, as described above, the cured product can be decomposed at a low temperature in a short time, and therefore the decomposed product can be effectively recovered. In particular, the decomposition of the cured product in this embodiment is preferably carried out by the above-described method for decomposing a cured product.

[0059] The present invention will be explained in more detail below with reference to examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. If the measuring instruments used in the examples are difficult to obtain due to discontinuation or the like, measurements can be made using other instruments with equivalent performance.

[0060] < １ H-NMR Analysis> １ The synthesis of the target compound was confirmed by H-NMR analysis. Instrument used: AVANCE III 500 (500 MHz) manufactured by Bruker Corporation

[0061] <Evaluation of Degradability of Cured Product> The degradability of the cured product was evaluated by cutting the resulting cured product into pieces 15 mm wide, 15 mm long, and 1 mm thick. Specifically, the cut cured product was immersed in 10 mL of decomposition solution and heated at 60°C, and the time required for the cured product to completely dissolve or liquefy was measured. Samples that dissolved or liquefied within 4 hours, 6 hours, and 8 hours were designated A, B, and C, respectively, and the sample that did not decompose within 8 hours was designated D.

[0062] Synthesis Example 1: Synthesis of 3-(2-aminoethylsulfanyl)propan-1-amine A mixture of 9.79 g (105 mmol) of allylamine hydrochloride (Tokyo Chemical Industry Co., Ltd.), 11.9 g (105 mmol) of cysteamine hydrochloride (Tokyo Chemical Industry Co., Ltd.), 1.75 g (10.6 mmol) of 2,2'-azobis(isobutyronitrile) (Fujifilm Wako Pure Chemical Industries, Ltd.), and 17.6 g of ethanol was bubbled with nitrogen gas for 15 minutes and then reacted at 75°C for 5 hours. After completion of the reaction, the reaction solution was concentrated and washed with ethanol, acetonitrile, and hexane. The resulting solid was dissolved in an aqueous sodium hydroxide solution and extracted with dichloromethane. The extract was concentrated to obtain 2.50 g (yield 18%) of 3-(2-aminoethylsulfanyl)propan-1-amine. The resulting 3-(2-aminoethylsulfanyl)propan-1-amine １ The results of H-NMR were as follows: １ H-NMR (CDCl３ , δppm): 1.28 (s, 4H), 1.75 (q, 2H), 2.58 (t, 2H), 2.63 (t, 2H), 2.80 (t, 2H), 2.88 (t, 2H)

[0063] Synthesis Example 2: Synthesis of 2-((2-(3-((2-aminoethyl)thio)-4-methylcyclohexyl)propyl)thio)ethanamine A mixture of 10.2 g (71.7 mmol) of (R)-(+)-limonene (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), 24.5 g (216 mmol) of cysteamine hydrochloride (manufactured by Tokyo Chemical Industry Co., Ltd.), 3.62 g (21.9 mmol) of 2,2′-azobis(isobutyronitrile) (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), and 24.0 g of ethanol was bubbled with nitrogen gas for 15 minutes and then reacted at 75° C. for 24 hours. After completion of the reaction, the reaction solution was concentrated and washed with ethanol, acetonitrile, and hexane. The obtained solid was dissolved in sodium hydroxide, extracted with dichloromethane, and the extract was concentrated to obtain 5.20 g (yield 25%) of 2-((2-(3-((2-aminoethyl)thio)-4-methylcyclohexyl)propyl)thio)ethanamine shown in Formula 3. １ The results of H-NMR were as follows: １ H-NMR (CDCl ３ , δppm): 0.96-1.09 (m, 6H), 1.28-1.88 (m, 13H), 2.34 (m, 3H), 2.60 (m, 4H), 2.87 (m, 4H)

[0064] Synthesis Example 3: Synthesis of bis(2-aminoethyl)-sulfoxide A mixture of 5 mL (43.7 mmol) of 2,2'-thiobis(ethylamine) (Tokyo Chemical Industry Co., Ltd.), 2.6 g (45.9 mmol) of 60 wt% hydrogen peroxide (Mitsubishi Gas Chemical Company, Inc.), and 43.0 g of pure water was reacted at 0°C for 30 minutes, and then at room temperature for 25 hours. After completion of the reaction, the reaction solution was concentrated. After drying in vacuo overnight, 4.88 g of bis(2-aminoethyl)-sulfoxide was obtained. １ The results of H-NMR were as follows: １ H-NMR (D ２ O, δppm): 3.02 (t, 4H), 3.10 (m, 4H)

[0065] Synthesis Example 4: Synthesis of bis(2-aminoethyl)-sulfone A mixture of 4 mL (35.0 mmol) of 2,2'-thiobis(ethylamine) (Tokyo Chemical Industry Co., Ltd.), 3.96 g (69.9 mmol) of 60 wt% hydrogen peroxide (Mitsubishi Gas Chemical Company, Inc.), and 37 g of pure water was reacted at 0°C for 30 minutes and then at room temperature for 24 hours. After completion of the reaction, the reaction solution was concentrated. After drying in vacuo overnight, 5.32 g of bis(2-aminoethyl)-sulfone was obtained. １ The results of H-NMR were as follows: １ H-NMR (D ２ O, δppm): 3.05 (t, 4H), 3.10-3.14 (m, 4H)

[0066] Example 1 An epoxy resin composition was prepared by mixing 86.1 parts by weight of bisphenol A epoxy resin (jER-828, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: approximately 190 g / eq) and 13.9 parts by weight of 2,2'-thiobis(ethylamine) (manufactured by Tokyo Chemical Industry Co., Ltd., active hydrogen equivalent: approximately 30 g / eq). This composition was heated at 80°C for 10 minutes and then at 100°C for 2 hours to obtain a cured product. The decomposition properties of the resulting cured product were measured according to the conditions described above using a decomposition liquid containing a 1:1 mixture of 35 wt% hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Company, Inc.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). The results are shown in Table 1.

[0067] Example 2 An epoxy resin composition was prepared by mixing 84.7 parts by weight of bisphenol A epoxy resin (jER-828, manufactured by Mitsubishi Chemical Corporation) and 15.3 parts by weight of 3-(2-aminoethylsulfanyl)propan-1-amine (active hydrogen equivalent: approximately 34 g / eq) obtained in Synthesis Example 1. This composition was heated at 80°C for 10 minutes, followed by heating at 90°C for 2 hours and then at 100°C for 1 hour to obtain a cured product. The decomposition properties of the resulting cured product were measured according to the conditions described above using a decomposition liquid containing a 1:1 mixture of 35 wt% hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Company, Inc.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). The results are shown in Table 1.

[0068] Example 3 An epoxy resin composition was prepared by mixing 71.9 parts by weight of bisphenol A epoxy resin (jER-828, manufactured by Mitsubishi Chemical Corporation) and 28.1 parts by weight of 2-((2-(3-((2-aminoethyl)thio)-4-methylcyclohexyl)propyl)thio)ethanamine (active hydrogen equivalent: approximately 73 g / eq) obtained in Synthesis Example 2. This composition was heated at 50°C for 10 minutes, followed by heating at 100°C for 2 hours and then at 110°C for 1 hour to obtain a cured product. The decomposition properties of the resulting cured product were measured according to the conditions described above, using a decomposition liquid prepared by mixing 35 wt% aqueous hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Company, Inc.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a weight ratio of 1:1, and the results are shown in Table 1.

[0069] Example 4 An epoxy resin composition was prepared by mixing 84.5 parts by weight of bisphenol A epoxy resin (jER-828, manufactured by Mitsubishi Chemical Corporation) and 15.5 parts by weight of bis(2-aminoethyl)-sulfoxide (active hydrogen equivalent: approximately 34 g / eq) obtained in Synthesis Example 3, and then heated at 70°C for 10 minutes and then at 100°C for 2 hours to obtain a cured product. The decomposition properties of the obtained cured product were measured according to the conditions described above using a decomposition liquid obtained by mixing 35 wt% hydrogen peroxide water (manufactured by Mitsubishi Gas Chemical Company, Inc.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a weight ratio of 1:1, and the results are shown in Table 1.

[0070] Example 5 An epoxy resin composition was prepared by mixing 83 parts by weight of bisphenol A epoxy resin (jER-828, manufactured by Mitsubishi Chemical Corporation) and 17 parts by weight of bis(2-aminoethyl)sulfone (active hydrogen equivalent: approximately 38 g / eq) obtained in Synthesis Example 4. This composition was heated at 70°C for 10 minutes and then at 100°C for 2 hours to obtain a cured product. The decomposition properties of the resulting cured product were measured according to the conditions described above, using a decomposition liquid prepared by mixing 35% by weight of aqueous hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Company, Inc.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a weight ratio of 1:1, and the results are shown in Table 1.

[0071] Example 6 8.00 g of cystamine dihydrochloride (Tokyo Chemical Industry Co., Ltd.), 6.03 g of potassium hydroxide (Fujifilm Wako Pure Chemical Industries, Ltd.), and 50.4 g of distilled water were mixed and stirred for 10 minutes, followed by extraction with dichloromethane. The extract was concentrated to obtain 4.96 g of cystamine. An epoxy resin composition was prepared by mixing 83.0 parts by weight of bisphenol A epoxy resin (jER-828, Mitsubishi Chemical Corporation) and 17.0 parts by weight of cystamine (active hydrogen equivalent: approximately 38 g / eq). The epoxy resin composition was heated at 50°C for 10 minutes, then heated at 100°C for 2 hours and then at 110°C for 1 hour to obtain a cured product. The decomposition properties of the obtained cured products were measured according to the above-mentioned conditions using a decomposition liquid containing a mixture of 35 wt % hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Company, Inc.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a weight ratio of 1:1. The results are shown in Table 1.

[0072] Example 7 An epoxy resin composition was prepared by mixing 82.3 parts by weight of bisphenol A epoxy resin (jER-828, manufactured by Mitsubishi Chemical Corporation), 16.3 parts by weight of isophorone diamine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., active hydrogen equivalent: approximately 43 g / eq), and 1.3 parts by weight of 2,2'-thiobis(ethylamine) (manufactured by Tokyo Chemical Industry Co., Ltd.). This composition was heated at 50°C for 10 minutes, followed by heating at 90°C for 2 hours and then at 100°C for 1 hour to obtain a cured product. The decomposition properties of the resulting cured product were measured according to the conditions described above using a 1:1 mixture of 35 wt% hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Company, Inc.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as the decomposition liquid, according to the conditions described above. The results are shown in Table 1. Isophorone diamine 2,2'-thiobis(ethylamine)

[0073] Example 8 An epoxy resin composition was prepared by mixing 83.6 parts by weight of bisphenol A epoxy resin (jER-828, manufactured by Mitsubishi Chemical Corporation), 11.0 parts by weight of isophoronediamine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 5.4 parts by weight of 2,2'-thiobis(ethylamine) (manufactured by Tokyo Chemical Industry Co., Ltd.). The composition was heated at 50°C for 10 minutes, followed by heating at 90°C for 2 hours and then at 100°C for 1 hour to obtain a cured product. The decomposition properties of the resulting cured product were measured according to the conditions described above using a 1:1 mixture of 35 wt% hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Company, Inc.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as the decomposition liquid, according to the conditions described above. The results are shown in Table 2.

[0074] Example 9 An epoxy resin composition was prepared by mixing 76.5 parts by weight of bisphenol A epoxy resin (jER-828, manufactured by Mitsubishi Chemical Corporation), 22.2 parts by weight of Jeffamine D-230 (manufactured by Tomoe Engineering Co., Ltd., active hydrogen equivalent: approximately 60 g / eq), and 1.3 parts by weight of 2,2'-thiobis(ethylamine) (manufactured by Tokyo Chemical Industry Co., Ltd.). This composition was heated at 50°C for 10 minutes, followed by heating at 90°C for 2 hours and then at 100°C for 1 hour to obtain a cured product. The decomposition properties of the resulting cured product were measured according to the conditions described above using a 1:1 mixture of 35 wt% hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Company, Inc.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as the decomposition liquid, and the results are shown in Table 2. Jeffamine D-230

[0075] Example 10 An epoxy resin composition was prepared by mixing 79.5 parts by weight of bisphenol A epoxy resin (jER-828, manufactured by Mitsubishi Chemical Corporation), 15.4 parts by weight of Jeffamine D-230 (manufactured by Tomoe Engineering Co., Ltd.), and 5.1 parts by weight of 2,2'-thiobis(ethylamine) (manufactured by Tokyo Chemical Industry Co., Ltd.). The composition was heated at 50°C for 10 minutes, followed by heating at 90°C for 2 hours and then at 100°C for 1 hour to obtain a cured product. The decomposition properties of the resulting cured product were measured according to the conditions described above using a 1:1 mixture of 35 wt% hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Company, Inc.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as the decomposition liquid, according to the conditions described above. The results are shown in Table 2.

[0076] Example 11 An epoxy resin composition was prepared by mixing 87.2 parts by weight of bisphenol A epoxy resin (jER-828, manufactured by Mitsubishi Chemical Corporation), 7.2 parts by weight of 1,5-diaminopentane (manufactured by Tokyo Chemical Industry Co., Ltd., active hydrogen equivalent: approximately 26 g / eq), and 5.6 parts by weight of 2,2'-thiobis(ethylamine) (manufactured by Tokyo Chemical Industry Co., Ltd.). This composition was heated at 50°C for 10 minutes, followed by heating at 90°C for 2 hours and then at 100°C for 1 hour to obtain a cured product. The decomposition properties of the resulting cured product were measured according to the conditions described above using a 1:1 mixture of 35 wt% hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Company, Inc.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as the decomposition liquid, according to the conditions described above. The results are shown in Table 2. 1,5-Diaminopentane

[0077] Example 12 An epoxy resin composition was prepared by mixing 86.8 parts by weight of bisphenol A epoxy resin (jER-828, manufactured by Mitsubishi Chemical Corporation), 4.8 parts by weight of 1,5-diaminopentane (manufactured by Tokyo Chemical Industry Co., Ltd.), and 8.4 parts by weight of 2,2'-thiobis(ethylamine) (manufactured by Tokyo Chemical Industry Co., Ltd.). This composition was heated at 50°C for 10 minutes, followed by heating at 90°C for 2 hours and then at 100°C for 1 hour to obtain a cured product. The decomposition properties of the resulting cured product were measured according to the conditions described above using a 1:1 mixture of 35 wt% hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Company, Inc.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as the decomposition liquid, according to the conditions described above. The results are shown in Table 2.

[0078] Comparative Example 1 An epoxy resin composition was prepared by mixing 81.9 parts by weight of bisphenol A epoxy resin (jER-828, manufactured by Mitsubishi Chemical Corporation) and 18.1 parts by weight of isophorone diamine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and a cured product was obtained by heating at 100°C for 3 hours. The decomposition properties of the resulting cured product were measured according to the conditions described above, using a decomposition liquid prepared by mixing 35% by weight of hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Company, Inc.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a weight ratio of 1:1, and the results are shown in Table 2.

[0079] Comparative Example 2 An epoxy resin composition was prepared by mixing 87.9 parts by weight of bisphenol A epoxy resin (jER-828, manufactured by Mitsubishi Chemical Corporation) and 12.1 parts by weight of 1,5-diaminopentane (manufactured by Tokyo Chemical Industry Co., Ltd.), and this composition was heated at 50°C for 10 minutes and then at 90°C for 2 hours to obtain a cured product. The decomposition properties of the resulting cured product were measured according to the conditions described above, using a decomposition liquid prepared by mixing 35% by weight of aqueous hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Company, Inc.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a weight ratio of 1:1, and the results are shown in Table 2.

[0080]

[0081] Example 13 The decomposition properties of the cured product obtained in Example 1 were evaluated according to the conditions described above using a decomposition liquid prepared by mixing 60% by weight of hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Company, Inc.) and Tween 80 (manufactured by Tokyo Chemical Industry Co., Ltd.) in a weight ratio of 63:7. The results are shown in Table 3.

[0082] Example 14 The decomposition properties of the cured product obtained in Example 1 were evaluated according to the conditions described above using a decomposition liquid prepared by mixing 60% by weight of hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Company, Inc.) and Sanisol B-50 (manufactured by Kao Corporation) in a weight ratio of 63:7. The results are shown in Table 3.

[0083] Example 15 The decomposition properties of the cured product obtained in Example 1 were evaluated according to the conditions described above using a decomposition liquid prepared by mixing 60 wt % hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Company, Inc.) and methyl acetate (manufactured by Tokyo Chemical Industry Co., Ltd.) in a weight ratio of 1:4. The results are shown in Table 3.

[0084] Example 16 The decomposition properties of the cured product obtained in Example 1 were evaluated according to the conditions described above using a decomposition liquid prepared by mixing 60 wt % hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Company, Inc.) and N,N-dimethylformamide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a weight ratio of 1:1. The results are shown in Table 3.

[0085] Example 17 The decomposition properties of the cured product obtained in Example 1 were evaluated according to the conditions described above using a decomposition liquid prepared by mixing 60 wt % hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Company, Inc.), acetonitrile (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and toluene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a weight ratio of 1:1:3. The results are shown in Table 3.

[0086] Example 18 The decomposition properties of the cured product obtained in Example 1 were evaluated according to the conditions described above using a decomposition liquid containing a mixture of 60 wt% hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Company, Inc.), acetonitrile (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.), 12-tungsto(VI) sodium phosphate n-hydrate (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.), and cetylpyridinium chloride monohydrate (manufactured by Tokyo Chemical Industry Co., Ltd.) in a weight ratio of 1:4:0.0027:0.0008. The results are shown in Table 3.

[0087] Comparative Example 3 The decomposition property of the cured product obtained in Comparative Example 1 was evaluated according to the conditions described above using a decomposition liquid prepared by mixing 60 wt % hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Company, Inc.) and Tween 80 (manufactured by Tokyo Chemical Industry Co., Ltd.) in a weight ratio of 63:7. The results are shown in Table 3.

[0088] Comparative Example 4 The decomposition property of the cured product obtained in Comparative Example 1 was evaluated according to the conditions described above using a decomposition liquid prepared by mixing 60 wt % hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Company, Inc.) and Sanisol B-50 (manufactured by Kao Corporation) in a weight ratio of 63:7. The results are shown in Table 4.

[0089] Comparative Example 5 The decomposition property of the cured product obtained in Comparative Example 1 was evaluated according to the conditions described above using a decomposition liquid prepared by mixing 60 wt % hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Company, Inc.) and methyl acetate (manufactured by Tokyo Chemical Industry Co., Ltd.) in a weight ratio of 1:4. The results are shown in Table 4.

[0090] Comparative Example 6 The decomposition property of the cured product obtained in Comparative Example 1 was evaluated according to the conditions described above using a decomposition liquid prepared by mixing 60 wt % hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Company, Inc.) and N,N-dimethylformamide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a weight ratio of 1:1. The results are shown in Table 4.

[0091] Comparative Example 7 The decomposition property of the cured product obtained in Comparative Example 2 was evaluated according to the conditions described above using a decomposition liquid prepared by mixing 60 wt % hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Company, Inc.) and Tween 80 (manufactured by Tokyo Chemical Industry Co., Ltd.) in a weight ratio of 63:7. The results are shown in Table 4.

[0092] Comparative Example 8 The decomposition property of the cured product obtained in Comparative Example 2 was evaluated according to the conditions described above using a decomposition liquid prepared by mixing 60 wt % hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Company, Inc.) and Sanisol B-50 (manufactured by Kao Corporation) in a weight ratio of 63:7. The results are shown in Table 4.

[0093] Comparative Example 9 The decomposition property of the cured product obtained in Comparative Example 2 was evaluated according to the conditions described above using a decomposition liquid prepared by mixing 60 wt % hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Company, Inc.) and methyl acetate (manufactured by Tokyo Chemical Industry Co., Ltd.) in a weight ratio of 1:4. The results are shown in Table 4.

[0094] Comparative Example 10 The decomposition property of the cured product obtained in Comparative Example 2 was evaluated according to the conditions described above using a decomposition liquid prepared by mixing 60 wt % hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Company, Inc.) and N,N-dimethylformamide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a weight ratio of 1:1. The results are shown in Table 4.

[0095]

[0096] Example 19 The decomposition liquid obtained in Example 17, in which 0.27 g of the decomposition product of the cured product was dissolved, was concentrated under reduced pressure at 30° C. to obtain a concentrate. Water was added to the obtained concentrate, and 0.19 g of a solid decomposition product was collected by filtration.

[0097] Example 20 The decomposition liquid obtained in Example 18, in which 0.27 g of the decomposition product of the cured product was dissolved, was concentrated under reduced pressure at 30° C. to obtain a concentrate. Water was added to the obtained concentrate, and 0.18 g of a solid decomposition product was collected by filtration.

[0098] As is clear from the above results, the decomposition method of this embodiment was excellent in decomposition ability.

[0099] 1, 11, 12 Curing agent 2, 21, 22 Curing resin 3, 31, 32 Cured product

Claims

1. A method for decomposing a cured product of a curable resin composition, comprising decomposing the cured product of the curable resin composition containing a compound having a thioethylamine structure using a decomposition solution containing a peroxide.

2. The decomposition method according to claim 1, wherein the thioethylamine structure is represented by formula (1). 【Chemistry 1】 (In equation (1), -X- is -S-, -S(=O)-, -S(=O) ２ -, -SS-, -SS(=O)-, -SS(=O) ２ -, -S(=O)-S(=O)-, -S(=O)-S(=O) ２ - or -S (=O) ２ -S (=O) ２ - indicates the connection point with other parts, and R １ Each of these is an independent substituent, R ２ m1 is an integer between 0 and 2.

3. The decomposition method according to claim 1 or 2, wherein the compound having the thioethylamine structure is a curing agent for a curable resin.

4. The decomposition method according to claim 1 or 2, wherein the compound having the thioethylamine structure is a curable resin.

5. The decomposition method according to claim 1 or 2, wherein the compound having the thioethylamine structure is a curable resin and a curing agent for the curable resin.

6. The decomposition method according to claim 1 or 2, wherein the peroxide contained in the decomposition solution includes hydrogen peroxide.

7. A method for recovering a filler, comprising decomposing a cured product of a curable resin composition containing a compound having a thioethylamine structure and a filler using a decomposition solution containing a peroxide to recover the filler.

8. The method for recovering a filler according to claim 7, wherein the decomposition of the cured product of the curable resin composition is carried out by the method described in claim 1 or 2.

9. The method for recovering a filler according to claim 7, wherein the filler contains reinforcing fibers.

10. A method for recovering decomposition products, comprising decomposing a cured product of a curable resin composition containing a compound having a thioethylamine structure using a decomposition solution containing a peroxide and a solvent, adding a poor solvent, and recovering the decomposition products in solid form by filtration.

11. The method for recovering a decomposition product according to claim 10, wherein the amount of solvent in the decomposition solution is reduced, and then the poor solvent is added.

12. A method for recovering decomposed products according to claim 10, wherein the decomposition of the cured product of the curable resin composition is carried out by the method described in claim 1 or 2.

13. A method for recovering decomposition products, comprising decomposing a cured product of a curable resin composition containing a compound having a thioethylamine structure and a filler using a decomposition solution containing a peroxide and a solvent to recover the filler, then adding a poor solvent and recovering the solid decomposition product by filtration.

14. The method for recovering a decomposition product according to claim 13, wherein the amount of solvent in the decomposition solution is reduced, and then the poor solvent is added.

15. A method for recovering decomposed products according to claim 13, wherein the decomposition of the cured product of the curable resin composition is carried out by the method described in claim 1 or 2.

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