WO2025100426A1 - Method for decomposing cured product of curable resin composition, method for recovering filler, and method for recovering decomposed product - Google Patents

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

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 the decomposed product.

Curable compounds such as epoxy resins are used in a wide variety of applications, including paints and adhesives, and also in automobile and wind turbine parts when combined with fillers (carbon fiber, glass fiber, etc.). When cured products of curable resin compositions containing such fillers are cured, it is difficult to decompose and remove the resin, and the filler is difficult to recover.

Thermal decomposition and dissolution methods are known as techniques for recovering fillers from the cured product of a curable resin composition that contains the filler (Patent Document 1). However, with the thermal decomposition method, there are concerns that the high temperature treatment can cause a deterioration in the quality of the filler and increase the environmental burden. On the other hand, although the dissolution method has milder conditions than the thermal decomposition method, lowering the treatment temperature to reduce the environmental burden tends to increase the treatment time.

JP 2022-015366 A

Under these circumstances, there is a demand for a technology that can decompose a cured product of a curable resin composition in a short time even at low temperatures.
The present invention aims to solve such problems, and to provide a method for decomposing a cured product of a curable resin composition, which can decompose the cured product of a curable resin composition at a lower temperature in a shorter time than conventional methods, a method for recovering a filler, and a method for recovering the decomposed product.

（式（１）中、－Ｘ－は、－Ｓ－、－Ｓ（＝Ｏ）－、－Ｓ（＝Ｏ）_２－、－Ｓ－Ｓ－、－Ｓ－Ｓ（＝Ｏ）－、－Ｓ－Ｓ（＝Ｏ）_２－、－Ｓ（＝Ｏ）－Ｓ（＝Ｏ）－、－Ｓ（＝Ｏ）－Ｓ（＝Ｏ）_２－または－Ｓ（＝Ｏ）_２－Ｓ（＝Ｏ）_２－であり、＊は他の部位との結合位置であり、Ｒ^１は、それぞれ独立に置換基であり、Ｒ^２は、水素原子または置換基である。ｍ１は０～２の整数である。）
＜３＞前記チオエチルアミン構造を有する化合物が、硬化性樹脂の硬化剤である、＜１＞または＜２＞に記載の分解方法。
＜４＞前記チオエチルアミン構造を有する化合物が、硬化性樹脂である、＜１＞または＜２＞に記載の分解方法。
＜５＞前記チオエチルアミン構造を有する化合物が、硬化性樹脂および硬化性樹脂の硬化剤である、＜１＞または＜２＞に記載の分解方法。
＜６＞前記分解液に含まれる過酸化物が過酸化水素を含む、＜１＞～＜５＞のいずれか１つに記載の分解方法。
＜７＞チオエチルアミン構造を有する化合物と充填剤を含む硬化性樹脂組成物の硬化物を、過酸化物を含む分解液を用いて分解して、充填剤を回収することを含む、充填剤の回収方法。
＜８＞前記硬化性樹脂組成物の硬化物の分解を、＜１＞～＜６＞のいずれか１つに記載の方法によって行う、＜７＞に記載の充填剤の回収方法。
＜９＞前記充填剤が強化繊維を含む、＜７＞または＜８＞に記載の充填剤の回収方法。
＜１０＞チオエチルアミン構造を有する化合物を含む硬化性樹脂組成物の硬化物を、過酸化物および溶媒を含む分解液を用いて分解して、貧溶媒を添加し、ろ過により固形状の分解物を回収することを含む、分解物の回収方法。
＜１１＞前記分解液中の溶媒の量を低減した後、前記貧溶媒を添加する、＜１０＞に記載の分解物の回収方法。
＜１２＞前記硬化性樹脂組成物の硬化物の分解を、＜１＞～＜６＞のいずれか１つに記載の方法によって行う、＜１０＞または＜１１＞に記載の分解物の回収方法。
＜１３＞チオエチルアミン構造を有する化合物と充填剤を含む硬化性樹脂組成物の硬化物を、過酸化物および溶媒を含む分解液を用いて分解して、充填剤を回収した後、貧溶媒を添加し、ろ過により固形状の分解物を回収することを含む、分解物の回収方法。
＜１４＞前記分解液中の溶媒の量を低減した後、前記貧溶媒を添加する、＜１３＞に記載の分解物の回収方法。
＜１５＞前記硬化性樹脂組成物の硬化物の分解を、＜１＞～＜６＞のいずれか１つに記載の方法によって行う、＜１３＞または＜１４＞に記載の分解物の回収方法。 In light of the above-mentioned problems, the present inventors have conducted studies and have 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 problems were solved by the following means.
<1> A method for decomposing a cured product of a curable resin composition, the method comprising decomposing the cured product of the 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- is -S-, -S(=O)-, -S(=O) ₂ -, -S-S-, -S-S(=O)-, -S-S(=O) ₂ -, -S(=O)-S(=O)-, -S(=O)-S(=O) ₂ - or -S(=O) ₂ -S(=O) ₂ -; * is a bonding position to another moiety; each R ¹ is independently a substituent; R ² is a hydrogen atom or a substituent; and 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 or 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 decomposition of the cured product of the curable resin composition is carried out by any one of the methods according to <1> to <6>.
<9> The method for recovering a filler according to <7> or <8>, wherein the filler contains reinforcing fibers.
<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 the 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 any one of the methods according to <1> to <6>.
<13> A method for recovering a decomposition product, the method 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 the solvent in the decomposition liquid is reduced and then the poor solvent is added.
<15> The method for recovering a decomposition product according to <13> or <14>, wherein the decomposition of the cured product of the curable resin composition is carried out by any one of the methods according to <1> to <6>.

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

FIG. 1 shows an image of a case where a compound having a thioethylamine structure is an amine-based curing agent for a curable resin. FIG. 2 shows an image diagram in which a compound having a thioethylamine structure is a thiol-based curing agent for a curable resin. FIG. 3 shows an image diagram in which a compound having a thioethylamine structure is a curable resin.

Hereinafter, an embodiment of the present invention (hereinafter, simply referred to as the present embodiment) will be described in detail. Note that the present embodiment is an example for explaining the present invention, and the present invention is not limited to the present embodiment.
In this specification, the word "to" is used to mean that the numerical values before and after it are included as the lower limit and upper limit.
In this specification, various physical properties and characteristic values are those at 23° C. unless otherwise specified.
In the description of groups (atomic groups) in this specification, the notation that does not indicate whether it is substituted or unsubstituted includes both groups (atomic groups) that have no substituents and groups (atomic groups) that have substituents. For example, "alkyl group" includes not only alkyl groups that have no substituents (unsubstituted alkyl groups), but also alkyl groups that have substituents (substituted alkyl groups). In this specification, the notation that does not indicate whether it is substituted or unsubstituted is preferably unsubstituted.
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 heterocyclic oxy 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 even more preferably an alkyl group. The formula weight of these substituents is preferably 15 or more, and preferably 200 or less. For example, the formula weight is 15 for a methyl group (-CH ₃ ). These substituents may further have a substituent, but it is preferable that they do not have a substituent.

In this specification, the term "process" refers not only to an independent process, but also to a process that cannot be clearly distinguished from other processes, as long as the intended effect of the process is achieved.
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.

Here, resin solids refers to the components other than the filler and solvent contained in the curable resin composition, including the curable resin, curing agent, and, if necessary, flame retardants, UV absorbers, antioxidants, silane coupling agents, etc.

The method for decomposing a cured product in this 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. By adopting such a configuration, the cured product of the curable resin composition can be decomposed in a short time at a lower temperature than before. As a result, the filler can be recovered while maintaining its quality.

　そして、チオエチルアミン構造を有する硬化物に過酸化物を添加することにより、Ｓの部分がＳ（＝Ｏ）_２となり（ただし、後述する式（１）で示す通り、そもそもＳ（＝Ｏ）_２の場合もある）、ＮがＮＯとなり、さらに、ＮＯがＮＯＨになる際にＮと隣接する炭素原子の間のＣ－Ｎ結合が切断されると推測される。そのため硬化物を容易に分解することができると推測される。
　特に、上記硬化物は、過酸化物により容易に切断される結合を構造中に含むため、従来よりも低温でも容易に硬化物を分解させることができる。さらに、分解時間も短くできる。
　また、上記硬化物は、過酸化物により容易に切断される結合を構造中に含むため、酸などを用いずに硬化物を分解できる点でも価値が高い。すなわち、酸で分解させる場合、硬化物、特に、充填剤が酸によってダメージを受けることがあるが、本実施形態の分解方法では、酸を用いずとも分解できるため、充填剤を回収する場合に有益である。また、酸で分解させる場合のように分解物の中和も必要ない。
　なお、チオエチルアミン構造は、チオエチルアミン構造を有する化合物一分子中に１つのみ含まれていてもよいし、２つ以上含まれていてもよい。 The cured product of the present embodiment has a thioethylamine structure in the cured product. In the following thioethylamine structure, the wavy line portion is bonded to another portion.

It is presumed that by adding a peroxide to a cured product having a thioethylamine structure, the S portion becomes S(=O) ₂ (however, as shown in formula (1) described later, there are cases where the S portion is S(=O) ₂ in the first place), N becomes NO, and when NO becomes NOH, the C-N bond between the N and the adjacent carbon atom is broken. Therefore, it is presumed that the cured product can be easily decomposed.
In particular, since the above-mentioned cured product contains in its structure bonds that are easily cleaved by peroxides, the cured product can be easily decomposed at lower temperatures than before. Furthermore, the decomposition time can be shortened.
In addition, the above-mentioned cured product contains bonds in its structure that are easily broken by peroxide, so it is valuable in that it can be decomposed without using acid or the like. That is, when decomposing with acid, the cured product, especially the filler, may be damaged by the acid, but the decomposition method of the present embodiment can decompose without using acid, which is useful when recovering the filler. Also, there is no need to neutralize the decomposed product as in the case of decomposing with acid.
The compound having a thioethylamine structure may contain only one thioethylamine structure or two or more thioethylamine structures in one molecule.

（式（１）中、－Ｘ－は、－Ｓ－、－Ｓ（＝Ｏ）－、－Ｓ（＝Ｏ）_２－、－Ｓ－Ｓ－、－Ｓ－Ｓ（＝Ｏ）－、－Ｓ－Ｓ（＝Ｏ）_２－、－Ｓ（＝Ｏ）－Ｓ（＝Ｏ）－、－Ｓ（＝Ｏ）－Ｓ（＝Ｏ）_２－または－Ｓ（＝Ｏ）_２－Ｓ（＝Ｏ）_２－であり、＊は他の部位との結合位置であり、Ｒ^１は、それぞれ独立に置換基であり、Ｒ^２は、水素原子または置換基である。ｍ１は０～２の整数である。） The curable resin composition according to the present embodiment includes a compound having a thioethylamine structure. The thioethylamine structure is preferably represented by formula (1).

(In formula (1), -X- is -S-, -S(=O)-, -S(=O) ₂ -, -S-S-, -S-S(=O)-, -S-S(=O) ₂ -, -S(=O)-S(=O)-, -S(=O)-S(=O) ₂ - or -S(=O) ₂ -S(=O) ₂ -; * is a bonding position to another moiety; each R ¹ is independently a substituent; R ² is a hydrogen atom or a substituent; and m1 is an integer of 0 to 2.)

In formula (1), -X- represents -S-, -S(=O)-, -S(=O) ₂ -, -S-S-, -S-S(=O)-, -S-S(=O) ₂ -, -S(=O)-S(=O)-, -S(=O)-S(=O) ₂ - or -S(=O) ₂ -S(=O) ₂ -, with -S-, -S(=O)- or -S(=O) ₂ - being preferred, and -S- being more preferred.
In formula (1), R ¹ is 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 heterocyclic oxy 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, even more preferably an alkyl group, even more preferably a linear alkyl group having 1 to 5 carbon atoms, and even more preferably a methyl group. The formula weight of the substituent is preferably 15 or more, and is preferably 200 or less, preferably 100 or less, more preferably 50 or less, and even more preferably 30 or less.

In formula (1), R ² is 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 heterocyclic oxy 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 even more preferably a hydrogen atom. The formula weight of the substituent is preferably 15 or more, and is 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.

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. The curable resin is preferably a thermosetting resin.

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 cures the curable resin (which may or may not have a thioethylamine structure), but it is preferable for the curing agent to have a thioethylamine structure and include a curing agent having an amino group and/or a thiol group.

When a compound having a thioethylamine structure is 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 making it equal to or greater than the lower limit, handling properties tend to be improved. In addition, 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 making it 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.

A first embodiment of the compound having a thioethylamine structure is a curing agent having an amino group (amine-based curing agent). The first embodiment will be described with reference to FIG.
FIG. 1 shows an image diagram of a case where a compound having a thioethylamine structure is an amine-based curing agent, in which 1 shows a curing agent (amine-based curing agent) for a curable resin, 2 shows a curable resin (epoxy resin), and 3 shows a partial structure of a cured product. As shown in FIG. 1, 1, the curing agent for a curable resin has a thioethylamine structure. The curing agent 1 reacts with an epoxy group of the curable resin 2 to form a cured product 3. It is presumed that such a cured product is immersed in a decomposition liquid containing a peroxide, whereby the C-N bond in the thioethylamine structure is broken (dotted line portion in FIG. 1), and the cured product 3 is decomposed. When the curable resin composition contains a filler, the filler can also be easily recovered.

（式（２）中、Ｒ^１は、それぞれ独立に、置換基であり、Ｒ^３は、置換基を有していてもよい炭化水素基であり、Ｒ^３中の炭化水素中に－Ｏ－、－Ｓ－、－ＮＨ－、－Ｃ（＝Ｏ）－、－Ｃ（＝Ｏ）Ｏ－および－Ｃ（＝Ｏ）ＮＨ－からなる群Ａの少なくとも１つの基を含んでいてもよく、前記群Ａの基に隣接する原子は炭素原子である。ｍ１は０～２の整数である。） The amine-based curing agent is more preferably an amine-based curing agent represented by formula (2).

(In formula (2), R ¹ 's are each independently a substituent, R ³ is a hydrocarbon group which may have a substituent, and the hydrocarbon in R ³ 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.)

In formula (2), ^R1 and m1 have the same meanings as ^R1 and m1 in formula (1), respectively, and the preferred ranges are also the same.
In formula (2), R ³ is a hydrocarbon group which may have a substituent, and the hydrocarbon in R ³ 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 the number of atoms connecting the N and S adjacent to R ³ is 1 to 18.

The hydrocarbon group which may have a substituent as ^R3 is preferably a non-aromatic aliphatic group which may have a substituent, more preferably a linear or branched aliphatic group which may have a substituent, and even more preferably a linear aliphatic group which has no substituent. 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 ³ is preferably a group consisting of two or more -CH ₂ -, or a group consisting of a combination of two or more -CH ₂ - and at least one group of group A consisting of -O-, -S-, -NH-, -C(=O)-, and -C(=O)O-, more preferably a group consisting of two or more -CH ₂ -, or a group consisting of a combination of two or more -CH ₂ - and -S-, and even more preferably a group consisting of two or more -CH ₂ -. Here, the group consisting of two or more -CH ₂ - is preferably a group consisting of 18 or less, more preferably 10 or less, even more preferably 6 or less, and even more preferably 4 or less -CH ₂ -.

Furthermore, the atom adjacent to the group A group 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. For example, when the non-aromatic chain hydrocarbon in ^R3 contains -O-, at least the structure taken is -C(R) ₂ -O-C(R) ₂ R- (R is a hydrogen atom or a substituent, and at least one of the Rs is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms).
In this embodiment, the number of atoms connecting the N and S adjacent to ^R3 is preferably 1 to 18. For example, in the case of the compound below, the number of atoms connecting the N and S adjacent to ^R3 is 8.

The number of atoms connecting N and S adjacent to ^R3 is preferably 2 or more, and is preferably 16 or less, more preferably 14 or less, and further preferably 12 or less, 10 or less, 8 or less, 6 or less, or 4 or less. By making it equal to or less than the upper limit, the flowability of the curable resin composition and the thermal properties of the cured product tend to be improved.

In the first embodiment of the compound having a thioethylamine structure, it is preferable that all of the atoms connecting the N and S adjacent ^{to R3} are carbon atoms, and it is more preferable that ^R3 is composed only of carbon atoms and hydrogen atoms.
The phrase "all atoms connecting N and S adjacent to ^R3 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) may be bonded to the carbon atom connecting N and S.

A preferred structure of ^R3 is shown below. One side is bonded to N of _NH2 in formula (2), and the other side 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.

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

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.

The second embodiment of 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 shows an image diagram of a case where a compound having a thioethylamine structure is a thiol-based curing agent, in which 11 indicates a curing agent for a curable resin (thiol-based curing agent), 21 indicates a curable resin (epoxy resin), and 31 indicates a partial structure of a 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 by immersing such a cured product in a decomposition liquid containing peroxide, the C-N bond in the thioethylamine structure (the dotted line portion in FIG. 2) is broken, and the cured product 31 is decomposed.

（式（３）中、Ｒ^１は、置換基であり、Ｒ^２は、水素原子または置換基であり、Ｒ^３は、置換基を有していてもよい炭化水素基であり、Ｒ^３中の炭化水素中に－Ｏ－、－Ｓ－、－ＮＨ－、－Ｃ（＝Ｏ）－、－Ｃ（＝Ｏ）Ｏ－および－Ｃ（＝Ｏ）ＮＨ－からなる群Ａの少なくとも１つの基を含んでいてもよく、前記群Ａの基に隣接する原子は炭素原子である。ｍ１は０～２の整数である。） The thiol-based curing agent is not particularly limited in terms of type, but is more preferably a thiol-based curing agent represented by formula (3).

(In formula (3), R ¹ is a substituent, R ² is a hydrogen atom or a substituent, R ³ is a hydrocarbon group which may have a substituent, and the hydrocarbon in R ³ 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.)

In formula (3), R ¹ , R ² and m1 have the same meanings as R ¹ , R ² and m1 in formula (1), respectively, and the preferred ranges are also the same.
In formula (3), ^R3 has the same meaning as ^R3 in formula (2), and the preferred range is also the same.

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

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

（式（４）中、Ｒ^１は、置換基であり、Ｒ^２は、水素原子または置換基であり、Ｒ^３は、置換基を有していてもよい非芳香族性の炭化水素基であり、Ｒ^３中の炭化水素中に－Ｏ－、－Ｓ－、－ＮＨ－、－Ｃ（＝Ｏ）－、－Ｃ（＝Ｏ）Ｏ－および－Ｃ（＝Ｏ）ＮＨ－からなる群Ａの少なくとも１つの基を含んでいてもよく、前記群Ａの基に隣接する原子は炭素原子である。ｍ１は０～２の整数である。） The aminothiol-based curing agent is not particularly limited in terms of type, but is preferably a curing agent represented by formula (4).

(In formula (4), R ¹ is a substituent, R ² is a hydrogen atom or a substituent, R ³ is a non-aromatic hydrocarbon group which may have a substituent, and the hydrocarbon in R ³ 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.)

In formula (4), R ¹ , R ² and m1 have the same meanings as R ¹ , R ² and m1 in formula (1), respectively, and the preferred ranges are also the same.
In formula (4), ^R3 has the same definition as ^R3 in formula (2), and the preferred range is also the same.

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

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 shows an image diagram of a case where a compound having a thioethylamine structure is a curable resin, where 12 indicates a curing agent for the curable resin, 22 indicates a curable resin (epoxy resin) which is a compound having a thioethylamine structure, and 32 indicates a partial structure of the cured product. As shown in 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 by immersing such a cured product in a decomposition liquid containing peroxide, the C-N bond in the thioethylamine structure (dotted line in FIG. 3) is broken, and the cured product 32 is decomposed.

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, but examples thereof include epoxy compounds, oxetane compounds, unsaturated polyesters, polyimides, and polyurethanes, and epoxy compounds are preferred.
The epoxy compound is not particularly limited as long as it has one or more epoxy groups in one 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, still more preferably 2 or 3, and even more preferably 2.
The number of thioethylamine structures in one molecule of the curable resin is preferably 1 or more (preferably 12 or less, more preferably 10 or less).

As described above, in the curable resin composition of this 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.

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. However, the curable resin is preferably a thermosetting resin, more preferably an epoxy compound, an oxetane compound, or an unsaturated polyester, and further preferably an epoxy compound.
The epoxy compound is not particularly limited as long as it is a compound having one or more (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) epoxy groups in one 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, polyfunctional 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 bonds of butadiene, etc. are epoxidized, and compounds obtained by reacting hydroxyl group-containing silicone compounds with epichlorohydrin. It is preferable to include a bisphenol-based epoxy compound.
For 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.

The content of the curable resin (curable resin without a thioethylamine structure and curable resin with 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 solid content in the curable resin composition. By making it equal to or more than the lower limit, the thermal properties of the cured product tend to be improved. In addition, 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 solid content in the curable resin composition. By making it equal to or less than the upper limit, the thermal properties of the cured product tend to be improved.
The curable resin composition in the present embodiment may contain only one type of curable resin, or may contain two or more types. When two or more types are contained, the total amount is preferably in the above range.

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. As for the curing agent without a thioethylamine structure, there is no particular restriction on the type, etc., as long as it can cure the curable resin having a thioethylamine structure. Examples of the curing agent include amine-based curing agents without 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 without a thioethylamine structure, Lewis acid amine complex-based curing agents, onium salt-based curing agents, imidazole-based curing agents, and urea-based curing agents.

Examples of amine-based curing agents not having 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; linear diamines represented by the formula (CH ₃ ) ₂ N(CH ₂ ) _n N(CH ₃ ) ₂ (wherein n is an integer of 1 to 10), (CH ₃ ) ₂ -N(CH ₂ ) n -CH ₃ Examples of the curing agents include linear tertiary amines represented by the formula: N{(CH ₂ )nCH ₃ } ₃ (wherein n is an integer from 0 to 10), alkyl tertiary monoamines represented by the formula: N{(CH 2 )nCH 3 } 3 (wherein n is an integer from 1 to 10), aliphatic aromatic amines such as benzyldimethylamine, 2-(dimethylaminomethyl)phenol, and 2,4,6-tris(dimethylaminomethyl)phenol, and 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, and the like. Among these, 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.

The content of the curing agent (curing agent having a thioethylamine structure and 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 in the present 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 is in the above range.

The curable resin composition used in the present embodiment may contain a filler.As the filler, fumed silica, precipitated silica, crystalline silica, fused silica, dolomite, silicic anhydride, hydrated silicic acid, and 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 oxide, silase balloon, glass microballoon, reinforced fiber (glass fiber, carbon fiber, etc.), reinforced fiber is preferable, and carbon fiber is more preferable.
The content of the filler in the curable resin composition used in the present embodiment, if included, 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 solid content.
The curable resin composition used in the present embodiment may contain only one type of filler, or may contain two or more types. When two or more types are contained, the total amount falls within the above range.

The curable resin composition used in this embodiment may contain components other than the curable compound and the curing agent. Specifically, it may contain reactive diluents, non-reactive diluents, curing accelerators, plasticizers, pigments, dyes, release agents, toughening agents, antioxidants, UV absorbers, light stabilizers, fluidizing agents, leveling agents, defoamers, flame retardants, thickeners, etc.

The cured product in this embodiment is formed from the above-described curable resin composition.
An example of the cured product is fiber reinforced plastic (FRP).
The cured product is preferably used for architectural paints, adhesives, automobile parts, aircraft parts, composite materials, printed circuit board materials, insulating impregnation materials for heavy electrical equipment, sealing materials for electronic elements, and the like.
In addition, cured products used for the applications described in paragraph 0045 of JP2018-83905A, the applications described in paragraph 0053 of JP2018-135433A, the applications described in paragraphs 0039 to 0043 of JP-T2016-527384A, and the applications described in paragraph 0048 of JP2011-213983A are also preferably used, and the contents of these applications are incorporated herein by reference.

On the other hand, the method for decomposing a cured product of the present embodiment includes decomposing the cured product of the curable resin composition using a decomposition liquid containing a peroxide. Since the cured product in the present embodiment has a thioethylamine structure, it can be easily decomposed by a peroxide. As a result, the filler contained in the cured product can be easily recovered.
There are no particular restrictions on the peroxide, so long as it is an organic compound having a peroxide structure (-O-O-) or a percarboxylic acid structure (-C(=O)-O-O-) as a functional group, or an inorganic compound containing a peroxide ion (O ₂ ^2- ). 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, etc. Among these, hydrogen peroxide is decomposed into harmless water and oxygen after the reaction, so that it is less likely to generate waste and is suitable for industrial use.
In this embodiment, the decomposition liquid preferably contains a peroxide in a ratio of 1 to 80% by weight, and more preferably contains a peroxide in a ratio of 10 to 60% by weight.
The decomposition method of the present embodiment is advantageous in that the cured material can be effectively decomposed and the filler can be recovered even when decomposition is performed using only hydrogen peroxide at low temperatures (for example, 50° C. or less, or even 40° C. or less) and at normal pressure.

The decomposition liquid in this embodiment may contain components other than peroxide.
The decomposition liquid in the present embodiment may contain at least one selected from the group consisting of a surfactant (preferably a nonionic surfactant, an ionic surfactant), a carboxylic acid (preferably formic acid, acetic acid), a heteropolyacid (preferably tungstophosphoric acid, molybdophosphoric acid), and a heteropolyacid salt (preferably sodium tungstophosphate (metal oxide), sodium molybdophosphate).
In this embodiment, the decomposition liquid may or may not contain a surfactant. If the decomposition liquid contains a surfactant, the content thereof is preferably 0% by weight or more, more preferably 0.01% by weight or more, and may be 1% by weight or more or 5% by weight or more, and is preferably 30% by weight or less, more preferably 20% by weight or less, and even more preferably 10% by weight or less, and may be 5% by weight or less, 1% by weight or less, or 0.1% by weight or less.
By including a surfactant, the decomposition property of the cured product and the solubility of the decomposition product tend to be improved.
In the present embodiment, when the decomposition liquid contains a carboxylic acid, the content thereof is preferably 1 to 80% by weight, and more preferably 20 to 60% by weight.
By including a carboxylic acid, the decomposition property of the cured product and the solubility of the decomposition product tend to be improved.
In the present embodiment, the decomposition liquid may be substantially free of carboxylic acid. For example, by using a peroxide and a surfactant in combination, the hardened material can be dissolved in the decomposition liquid, and the filler can be appropriately recovered.
In the present embodiment, when the decomposition liquid contains a heteropolyacid and/or a heteropolyacid salt, the content thereof is preferably 0.02% by weight or more, more preferably 0.04% by weight or more, and is preferably 1% by weight or less, more preferably 0.5% by weight or less, and even more preferably 0.1% by weight 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.

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 be 45% by weight or less, with the lower limit being 0% by weight or more. By making the water content 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 the organic solvent 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 the hydrocarbon solvent include aromatic hydrocarbon solvents such as benzene, toluene, and m-xylene, and aliphatic hydrocarbon solvents such as ethane, hexane, octane, and heptane, and aromatic hydrocarbon solvents are preferred. Examples of the nitrile solvent include acetonitrile, propionitrile, and benzonitrile, and acetonitrile is preferred.
By including a solvent other than water, the solubility of the decomposition products tends to be improved.
In the present embodiment, when the decomposition liquid contains a solvent other than water, the content thereof is preferably 1 to 90% by weight, and more preferably 10 to 80% by weight.

These components other than peroxides may contain only one type, or two or more types.

In the decomposition method of the present embodiment, the decomposition temperature can be 150° C. or lower, and can further be 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, may be 45° C. or higher, 50° C. or higher, 55° C. or higher, or may be 60° C. or higher.
This embodiment is highly valuable in that decomposition can be effectively promoted without increasing the decomposition temperature.
In addition, in the decomposition method of the present embodiment, the decomposition temperature can be set to be 5° C. or more, and 10° C. or more lower than the glass transition temperature of the cured product.
The decomposition temperature means the temperature of the decomposition liquid. The glass transition temperature is measured in accordance with ISO 11357-2.

In the decomposition method of this embodiment, the decomposition time can be determined as appropriate, but for example, when the cured material is cut to a size of 15 mm wide, 15 mm long, and 1 mm thick and immersed in 10 mL of decomposition liquid, the decomposition time can be 8 hours or less, and more than 1 hour is practical.

In the decomposition method of this embodiment, the pKa of each component contained in the decomposition liquid is preferably 0 or more, more preferably 2 or more, and even more preferably 3 or more. There is no particular upper limit, but the pKa is usually 13 or less. Furthermore, if the decomposition liquid contains a carboxylic acid, the pKa is preferably 0 to 5.

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

A first embodiment of the method for recovering the decomposition product of the present embodiment includes 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.
A second embodiment of the method for recovering the decomposition product of the present 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 a solvent, recovering the filler, adding a poor solvent, and recovering a solid decomposition product by filtration.
As a method for recovering the decomposition products, it is preferable to add a poor solvent after reducing the amount of the solvent in the decomposition liquid. By adding the poor solvent, it becomes possible to remove the organic solvent (toluene or acetonitrile), water, and peroxides in the decomposition liquid and efficiently recover the solid decomposition products.
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% by weight or less, more preferably 10% by weight or less, even more preferably 5% by weight or less, even more preferably 1% by weight or less, even more preferably 0.5% by weight or less, and even more preferably 0.1% by weight or less. Examples of poor solvents include water, alcohols such as methanol and ethanol, aliphatic hydrocarbon solvents such as ethane, hexane, octane, and heptane, acetone, etc., and water is preferred. By using such a poor solvent, the decomposition product can be efficiently precipitated from the solution after decomposing the cured product. Alternatively, the hydrophilic compound and the solvent of the decomposition liquid can be more easily separated.
In the present embodiment, the decomposition product can be recovered by, 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 concentrate to precipitate the decomposition product, and the solid decomposition product is recovered by filtration. As described above, the cured product can be decomposed at low temperature in a short time, and therefore the decomposition product can be effectively recovered. In particular, the decomposition of the cured product in the present embodiment is preferably performed by the above-mentioned method for decomposing a cured product.

The present invention will be described in more detail below with reference to examples. The materials, amounts, ratios, processing contents, processing procedures, etc. shown in the following examples can be appropriately changed 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.

< ^1H -NMR Analysis>
The synthesis of the target product was confirmed by ¹ H-NMR analysis.
Equipment used: Bruker AVANCEIII500 (500MHz)

<Evaluation of decomposition property of cured product>
The decomposition property of the cured product was evaluated by cutting the obtained cured product into a size of 15 mm wide, 15 mm long, and 1 mm thick. Specifically, the cut cured product was immersed in 10 mL of decomposition liquid 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 indicated as A, B, and C, respectively, and a sample that did not decompose within 8 hours was indicated as D.

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 the reaction was completed, the reaction solution was concentrated and washed with ethanol, acetonitrile, and hexane. The obtained solid was dissolved in an aqueous sodium hydroxide solution and extracted with dichloromethane, and the extract was concentrated to obtain 2.50 g (yield 18%) of 3-(2-aminoethylsulfanyl)propan-1-amine.
^{The 1} H-NMR results of the obtained 3-(2-aminoethylsulfanyl)propan-1-amine are shown below.
¹ H-NMR (CDCl ₃ , 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)

<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 the reaction was completed, the reaction solution was concentrated and washed with ethanol, acetonitrile, and hexane. The obtained solid was dissolved in sodium hydroxide and 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.
The results of ¹ H-NMR of the resulting 2-((2-(3-((2-aminoethyl)thio)-4-methylcyclohexyl)propyl)thio)ethanamine were as shown below.
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)

<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 Co., Ltd.), 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 vacuum overnight, 4.88 g of bis(2-aminoethyl)-sulfoxide was obtained.
^{The 1} H-NMR results of the obtained bis(2-aminoethyl)-sulfoxide were as shown below.
¹ H-NMR (D ₂ O, δppm): 3.02 (t, 4H), 3.10 (m, 4H)

<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 Co., Ltd.), 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 vacuum overnight, 5.32 g of bis(2-aminoethyl)-sulfone was obtained.
^{The 1} H-NMR results of the obtained bis(2-aminoethyl)-sulfone were as shown below.
¹ H-NMR (D ₂ O, δppm): 3.05 (t, 4H), 3.10-3.14 (m, 4H)

Example 1
An epoxy resin composition was prepared by mixing 86.1 parts by weight of bisphenol A type epoxy resin (jER-828, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent of about 190 g/eq) and 13.9 parts by weight of 2,2'-thiobis(ethylamine) (manufactured by Tokyo Chemical Industry Co., Ltd., active hydrogen equivalent of about 30 g/eq), and then 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 obtained cured product were measured according to the above-mentioned conditions using a mixture of 35% by weight hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a weight ratio of 1:1 as the decomposition liquid, and the results are shown in Table 1.

Example 2
An epoxy resin composition was prepared by mixing 84.7 parts by weight of bisphenol A type 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: about 34 g/eq) obtained in Synthesis Example 1, and then heated at 80°C for 10 minutes, followed by heating at 90°C for 2 hours and at 100°C for 1 hour to obtain a cured product. The decomposition properties of the obtained cured product were measured according to the above-mentioned conditions using a mixture of 35% by weight 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 as the decomposition liquid, and the results are shown in Table 1.

Example 3
An epoxy resin composition was prepared by mixing 71.9 parts by weight of bisphenol A type 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: about 73 g/eq) obtained in Synthesis Example 2, and then heated at 50°C for 10 minutes, followed by heating at 100°C for 2 hours and at 110°C for 1 hour to obtain a cured product. The decomposition property of the obtained cured product was measured according to the above-mentioned conditions using a mixture of 35% by weight 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 as a decomposition liquid, and the results are shown in Table 1.

Example 4
An epoxy resin composition was prepared by mixing 84.5 parts by weight of bisphenol A type epoxy resin (jER-828, manufactured by Mitsubishi Chemical Corporation) and 15.5 parts by weight of bis(2-aminoethyl)-sulfoxide (active hydrogen equivalent: about 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 property of the obtained cured product was measured according to the above-mentioned conditions using a mixture of 35% by weight 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 as the decomposition liquid, and the results are shown in Table 1.

Example 5
An epoxy resin composition was prepared by mixing 83 parts by weight of bisphenol A type epoxy resin (jER-828, manufactured by Mitsubishi Chemical Corporation) and 17 parts by weight of bis(2-aminoethyl)-sulfone (active hydrogen equivalent: about 38 g/eq) obtained in Synthesis Example 4, 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 above-mentioned conditions using a mixture of 35% by weight of 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 as the decomposition liquid, and the results are shown in Table 1.

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, and then extracted 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 type epoxy resin (jER-828, manufactured by Mitsubishi Chemical Corporation) and 17.0 parts by weight of cystamine (active hydrogen equivalent: about 38 g/eq), and then heated at 50° C. for 10 minutes, followed by heating at 100° C. for 2 hours and at 110° C. for 1 hour to obtain a cured product. The decomposition properties of the obtained cured product were measured according to the above-mentioned conditions using a mixture of 35% by weight 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 as the decomposition liquid, and the results are shown in Table 1.

２，２’－チオビス（エチルアミン）

Example 7
An epoxy resin composition was prepared by mixing 82.3 parts by weight of bisphenol A type 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 of about 43 g/eq), and 1.3 parts by weight of 2,2'-thiobis(ethylamine) (manufactured by Tokyo Chemical Industry Co., Ltd.), and the composition was heated at 50°C for 10 minutes, followed by heating at 90°C for 2 hours and at 100°C for 1 hour to obtain a cured product. The decomposition properties of the obtained cured product were measured according to the above-mentioned conditions using a mixture of 35% by weight hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a weight ratio of 1:1 as the decomposition liquid, and the results are shown in Table 1.
Isophoronediamine

2,2'-thiobis(ethylamine)

Example 8
An epoxy resin composition was prepared by mixing 83.6 parts by weight of bisphenol A type epoxy resin (jER-828, manufactured by Mitsubishi Chemical Corporation), 11.0 parts by weight of isophorone diamine (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.), and the composition was heated at 50°C for 10 minutes, followed by heating at 90°C for 2 hours and at 100°C for 1 hour to obtain a cured product. The decomposition properties of the obtained cured product were measured according to the above-mentioned conditions using a mixture of 35% by weight hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a weight ratio of 1:1 as the decomposition liquid, and the results are shown in Table 2.

<Example 9>
An epoxy resin composition was prepared by mixing 76.5 parts by weight of bisphenol A type 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 of about 60 g/eq), and 1.3 parts by weight of 2,2'-thiobis(ethylamine) (manufactured by Tokyo Chemical Industry Co., Ltd.), and the composition was heated at 50°C for 10 minutes, followed by heating at 90°C for 2 hours and at 100°C for 1 hour to obtain a cured product. The decomposition properties of the obtained cured product were measured according to the above-mentioned conditions using a mixture of 35% by weight hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a weight ratio of 1:1 as the decomposition liquid, and the results are shown in Table 2.
Jeffamine D-230

Example 10
An epoxy resin composition was prepared by mixing 79.5 parts by weight of bisphenol A type 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.), and the composition was heated at 50°C for 10 minutes, followed by heating at 90°C for 2 hours and at 100°C for 1 hour to obtain a cured product. The decomposition properties of the cured product were measured according to the above-mentioned conditions using a mixture of 35% by weight hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a weight ratio of 1:1 as the decomposition liquid, and the results are shown in Table 2.

Example 11
An epoxy resin composition was prepared by mixing 87.2 parts by weight of bisphenol A type 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 of about 26 g/eq), and 5.6 parts by weight of 2,2'-thiobis(ethylamine) (manufactured by Tokyo Chemical Industry Co., Ltd.), and a cured product was obtained by heating at 50°C for 10 minutes, followed by heating at 90°C for 2 hours and at 100°C for 1 hour. The decomposition properties of the obtained cured product were measured according to the above-mentioned conditions using a mixture of 35% by weight hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a weight ratio of 1:1 as the decomposition liquid, and the results are shown in Table 2.
1,5-Diaminopentane

Example 12
An epoxy resin composition was prepared by mixing 86.8 parts by weight of bisphenol A type 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.), and the composition was heated at 50°C for 10 minutes, followed by heating at 90°C for 2 hours and at 100°C for 1 hour to obtain a cured product. The decomposition properties of the cured product were measured according to the above-mentioned conditions using a mixture of 35% by weight hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a weight ratio of 1:1 as the decomposition liquid, and the results are shown in Table 2.

<Comparative Example 1>
An epoxy resin composition was prepared by mixing 81.9 parts by weight of bisphenol A type 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 obtained cured product were measured according to the above-mentioned conditions using a mixture of 35% by weight hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Industry Co., Ltd.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a weight ratio of 1:1 as the decomposition liquid, and the results are shown in Table 2.

<Comparative Example 2>
An epoxy resin composition was prepared by mixing 87.9 parts by weight of bisphenol A type 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 the 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 cured product were measured according to the above-mentioned conditions using a mixture of 35% by weight hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) and acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a weight ratio of 1:1 as the decomposition liquid, and the results are shown in Table 2.

<Example 13>
The decomposition property of the cured product obtained in Example 1 was evaluated according to the above-mentioned conditions using a decomposition liquid prepared by mixing 60% by weight of hydrogen peroxide (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.

<Example 14>
The decomposition property of the cured product obtained in Example 1 was evaluated according to the above-mentioned conditions using a decomposition liquid prepared by mixing 60% by weight of hydrogen peroxide (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.

<Example 15>
The decomposition property of the cured product obtained in Example 1 was evaluated according to the above-mentioned conditions using a decomposition liquid prepared by mixing 60% by weight of hydrogen peroxide (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.

<Example 16>
The decomposition property of the cured product obtained in Example 1 was evaluated according to the above-mentioned conditions using a decomposition liquid prepared by mixing 60% by weight of hydrogen peroxide (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.

<Example 17>
The decomposition property of the cured product obtained in Example 1 was evaluated according to the above-mentioned conditions using a decomposition liquid that was a mixture of 60 wt% hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Co., 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.

<Example 18>
The decomposition property of the cured product obtained in Example 1 was evaluated according to the above-mentioned conditions using a mixture of 60% by weight hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Co., Ltd.), 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 as a decomposition liquid. The results are shown in Table 3.

<Comparative Example 3>
For the cured product obtained in Comparative Example 1, decomposition property was evaluated according to the above-mentioned conditions using a decomposition liquid prepared by mixing 60% by weight of hydrogen peroxide (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.

<Comparative Example 4>
For the cured product obtained in Comparative Example 1, decomposition property was evaluated according to the above-mentioned conditions using a decomposition liquid prepared by mixing 60% by weight of hydrogen peroxide (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.

<Comparative Example 5>
The decomposition property of the cured product obtained in Comparative Example 1 was evaluated according to the above-mentioned conditions using a decomposition liquid prepared by mixing 60% by weight of hydrogen peroxide (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.

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

<Comparative Example 7>
For the cured product obtained in Comparative Example 2, decomposition property was evaluated according to the above-mentioned conditions 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.

<Comparative Example 8>
For the cured product obtained in Comparative Example 2, decomposition property was evaluated according to the above-mentioned conditions 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.

<Comparative Example 9>
The decomposition property of the cured product obtained in Comparative Example 2 was evaluated according to the above-mentioned conditions using a decomposition liquid prepared by mixing 60% by weight of hydrogen peroxide (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.

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

<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 concentrate, and 0.19 g of a solid decomposition product was collected by filtration.

<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.

As is clear from the above results, the decomposition method of this embodiment had excellent decomposition properties.

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

Claims (15)

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 liquid containing a peroxide. The decomposition method according to claim 1 , wherein the thioethylamine structure is represented by formula (1).

(In formula (1), -X- is -S-, -S(=O)-, -S(=O) ₂ -, -S-S-, -S-S(=O)-, -S-S(=O) ₂ -, -S(=O)-S(=O)-, -S(=O)-S(=O) ₂ - or -S(=O) ₂ -S(=O) ₂ -; * is a bonding position to another moiety; each R ¹ is independently a substituent; R ² is a hydrogen atom or a substituent; and m1 is an integer of 0 to 2.) The decomposition method according to claim 1 or 2, wherein the compound having a thioethylamine structure is a curing agent for a curable resin. The decomposition method according to claim 1 or 2, wherein the compound having a thioethylamine structure is a curable resin. The decomposition method according to claim 1 or 2, wherein the compound having a thioethylamine structure is a curable resin and a curing agent for the curable resin. The decomposition method according to any one of claims 1 to 5, wherein the peroxide contained in the decomposition liquid includes hydrogen peroxide. 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 to recover the filler. The method for recovering a filler according to claim 7, in which the decomposition of the cured product of the curable resin composition is carried out by the method according to any one of claims 1 to 6. The method for recovering a filler according to claim 7 or 8, wherein the filler contains reinforcing fibers. 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. The method for recovering decomposition products according to claim 10, wherein the amount of solvent in the decomposition liquid is reduced, and then the poor solvent is added. The method for recovering the decomposition product according to claim 10 or 11, in which the decomposition of the cured product of the curable resin composition is carried out by the method according to any one of claims 1 to 6. 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 the solid decomposition product by filtration. The method for recovering decomposition products according to claim 13, wherein the amount of solvent in the decomposition liquid is reduced, and then the poor solvent is added. The method for recovering the decomposition product according to claim 13 or 14, in which the decomposition of the cured product of the curable resin composition is carried out by the method according to any one of claims 1 to 6.

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