JP2024048992A - Bisphenol composition, method for producing bisphenol composition, method for producing epoxy resin, and method for producing cured epoxy resin - Google Patents

Abstract

[Problem] To provide a bisphenol composition with little coloration. [Solution] A solid bisphenol composition comprising a bisphenol metal alkoxide and a bisphenol glycerin ether metal alkoxide represented by general formula (1) (wherein R is each independently a hydrogen atom, a halogen atom, or an alkyl group having from 1 to 4 carbon atoms; X is each independently a direct bond, a hydrocarbon group having from 1 to 14 carbon atoms, a halogenated hydrocarbon group having from 1 to 14 carbon atoms, -SO2-, -S-, -CO-, or -O-; M is each independently an alkali metal, an alkaline earth metal, magnesium, or aluminum; n is the valence of M), in which the ratio of the content of the bisphenol glycerin ether metal alkoxide to the content of the bisphenol metal alkoxide is 15 mass% or less. TIFF2024048992000011.tif31170 [Selected Figures] None

Description

The present invention relates to a bisphenol composition, a method for producing a bisphenol composition, a method for producing an epoxy resin, and a method for producing a cured epoxy resin.

Epoxy resin is an important material that is used in a variety of applications, such as adhesives, insulating materials, paints, casting materials, and composite materials, due to its excellent adhesiveness, electrical properties, and heat resistance. The epoxy resin cured material obtained by curing this epoxy resin does not melt easily, and is difficult to dissolve in general-purpose solvents. This is because the epoxy resin cured material has a complex structure that is crosslinked three-dimensionally.

In light of the recent trend towards carbon neutrality, there is a demand for chemical recycling of epoxy resin cured materials back into the monomer raw materials. Under these circumstances, a bisphenol composition is known that can be obtained by chemical recycling from epoxy resin cured materials (Non-Patent Document 1).

Green Chem.,2021,23,6356-6360

In the method disclosed in Non-Patent Document 1, a cured epoxy resin is converted into an easily decomposable acetate ester by oxidizing it in an acetic acid solvent under an atmosphere of hydrogen peroxide or oxygen, and bisphenol A is obtained from the resulting acetate ester. However, the harsh conditions of the oxidation reaction are necessary, and column purification is required to obtain the acetate ester from the complex mixture, making it difficult to commercialize.

In addition, the bisphenol composition obtained by other conventional chemical recycling of epoxy resin cured products is a complex mixture containing impurities derived from decomposition catalysts. The impurities also include components that cause discoloration. Therefore, there is a problem that the bisphenol composition obtained by chemical recycling of epoxy resin cured products and the recycled resin produced by reusing this bisphenol A composition are discolored. Therefore, in order to obtain recycled resin with good color tone, it is required that the bisphenol composition is less discolored, even if it is obtained by chemical recycling.

The present invention has been made in consideration of the above circumstances, and aims to provide a bisphenol composition with little coloration. It also aims to provide a method for producing an epoxy resin using the bisphenol composition. It also aims to provide a method for producing a cured epoxy resin product using the epoxy resin obtained by the method for producing an epoxy resin.

As a result of investigations conducted by the inventors to solve the above problems, they discovered that a bisphenol composition containing a metal alkoxide of bisphenol glycerin ether is less colored. That is, the gist of the present invention includes the following.

（一般式（１）中、Ｒは、それぞれ独立に、水素原子、ハロゲン原子、又は炭素数１以上４以下のアルキル基であり；Ｘは、それぞれ独立に、直接結合、炭素数１以上１４以下の炭化水素基、炭素数１以上１４以下のハロゲン化炭化水素基、－ＳＯ_２－、－Ｓ－、－ＣＯ－、又は－Ｏ－であり；Ｍは、それぞれ独立に、アルカリ金属、アルカリ土類金属、マグネシウム、又はアルミニウムであり；ｎは、Ｍの価数である。）
〔２〕
前記ビスフェノール金属アルコキシドの含有量に対する前記ビスフェノールグリセリンエーテル金属アルコキシドの含有量の比率が、０．１質量ｐｐｍ以上である、〔１〕に記載のビスフェノール組成物。
〔３〕
前記ビスフェノール金属アルコキシドが、一般式（２）で表される化合物である、〔１〕又は〔２〕に記載のビスフェノール組成物。

（一般式（２）中、Ｒ、Ｘ、Ｍ、及びｎは、それぞれ、一般式（１）中のＲ、Ｘ、Ｍ、及びｎと同義である。）
〔４〕
前記一般式（１）中、Ｒが水素原子であり、Ｘがジメチルメチレン基である、〔１〕～〔３〕のいずれかに記載のビスフェノール組成物。
〔５〕
前記一般式（１）中、Ｍがアルカリ金属である、〔１〕～〔４〕のいずれかに記載のビスフェノール組成物。
〔６〕
前記一般式（１）中、Ｍがアルカリ土類金属である、〔１〕～〔４〕のいずれかに記載のビスフェノール組成物。
〔７〕
〔１〕～〔６〕のいずれかに記載のビスフェノール組成物を製造する方法であって、以下の工程Ａ～工程Ｃを含む、ビスフェノール組成物の製造方法。
工程Ａ：熱硬化性樹脂硬化物を分解し、前記ビスフェノール金属アルコキシド及び前記ビ
スフェノールグリセリンエーテル金属アルコキシドを含む分解液Ａを得る工程
工程Ｂ：工程Ａで得られた分解液Ａに水を加え、油水２相液Ｂを得る工程
工程Ｃ：工程Ｂで得られた油水２相液Ｂを油水分離し、得られた水相Ｃと有機溶媒とを混合し、懸濁液Ｄを得る工程
工程Ｄ：工程Ｃで得られた懸濁液Ｄを固液分離し、固相を回収する工程
〔８〕
前記工程Ｂが、前記工程Ａで得られた分解液Ａを固液分離して不溶解物を除去した分解液Ａ’を得て、該分解液Ａ’に水を加えることで油水２相液Ｂを得る工程である、〔７〕に記載のビスフェノール組成物の製造方法。
〔９〕
〔１〕～〔６〕のいずれかに記載のビスフェノール組成物とエピハロヒドリンとを接触させ、前記ビスフェノール組成物中の前記ビスフェノール金属アルコキシドと、前記ビスフェノールグリセリンエーテル金属アルコキシドと、前記エピハロヒドリンとを反応させる工程を含む、エポキシ樹脂の製造方法。
〔１０〕
〔９〕に記載の製造方法で得られたエポキシ樹脂と、多価ヒドロキシ化合物とを反応させる工程を含む、エポキシ樹脂の製造方法。
〔１１〕
〔９〕又は〔１０〕に記載の製造方法で得られたエポキシ樹脂と硬化剤とを含むエポキシ樹脂組成物を硬化する工程を含む、エポキシ樹脂硬化物の製造方法。 [1]
The metal alkoxide is a bisphenol metal alkoxide represented by general formula (1),
A solid bisphenol composition, wherein the ratio of the content of the bisphenol glycerin ether metal alkoxide to the content of the bisphenol metal alkoxide is 15 mass % or less.

(In general formula (1), each R is independently a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms; each X is independently a direct bond, a hydrocarbon group having 1 to 14 carbon atoms, a halogenated hydrocarbon group having 1 to 14 carbon atoms, -SO ₂ -, -S-, -CO-, or -O-; each M is independently an alkali metal, an alkaline earth metal, magnesium, or aluminum; and n is the valence of M.)
[2]
The bisphenol composition according to [1], wherein the ratio of the content of the bisphenol glycerin ether metal alkoxide to the content of the bisphenol metal alkoxide is 0.1 ppm by mass or more.
[3]
The bisphenol composition according to [1] or [2], wherein the bisphenol metal alkoxide is a compound represented by general formula (2):

(In general formula (2), R, X, M, and n are the same as R, X, M, and n in general formula (1), respectively.)
[4]
The bisphenol composition according to any one of [1] to [3], wherein in the general formula (1), R is a hydrogen atom and X is a dimethylmethylene group.
[5]
The bisphenol composition according to any one of [1] to [4], wherein in the general formula (1), M is an alkali metal.
[6]
The bisphenol composition according to any one of [1] to [4], wherein in the general formula (1), M is an alkaline earth metal.
[7]
A method for producing the bisphenol composition according to any one of [1] to [6], comprising the following steps A to C:
Step A: A step of decomposing a cured thermosetting resin material to obtain a decomposition liquid A containing the bisphenol metal alkoxide and the bisphenol glycerin ether metal alkoxide. Step B: A step of adding water to the decomposition liquid A obtained in step A to obtain an oil-water two-phase liquid B. Step C: A step of subjecting the oil-water two-phase liquid B obtained in step B to oil-water separation, mixing the obtained aqueous phase C with an organic solvent, and obtaining a suspension D. Step D: A step of subjecting the suspension D obtained in step C to solid-liquid separation, and recovering the solid phase [8].
The method for producing a bisphenol composition according to [7], wherein the step B is a step of obtaining a decomposition liquid A' by subjecting the decomposition liquid A obtained in the step A to solid-liquid separation to remove insoluble matter, and obtaining an oil-water two-phase liquid B by adding water to the decomposition liquid A'.
[9]
A method for producing an epoxy resin, comprising the steps of contacting the bisphenol composition according to any one of [1] to [6] with epihalohydrin, and reacting the bisphenol metal alkoxide in the bisphenol composition, the bisphenol glycerin ether metal alkoxide, and the epihalohydrin.
[10]
A method for producing an epoxy resin, comprising a step of reacting the epoxy resin obtained by the method according to [9] with a polyvalent hydroxy compound.
[11]
A method for producing an epoxy resin cured product, comprising a step of curing an epoxy resin composition containing the epoxy resin obtained by the method for producing an epoxy resin cured product according to [9] or [10] and a curing agent.

The present invention provides a bisphenol composition with little coloration. In addition, the bisphenol composition can be used to produce an epoxy resin. Furthermore, the epoxy resin can be cured to produce a cured epoxy resin.

The following describes in detail the embodiments of the present invention, but the present invention is not limited to the following description, and can be modified as desired without departing from the spirit of the present invention. In this specification, when "~" is used to express a numerical value or physical property value, it is used to include the values before and after it.

1. Bisphenol Composition
A first embodiment of the present invention is a solid bisphenol composition comprising a bisphenol metal alkoxide and a bisphenol glycerin ether metal alkoxide having a specific structure. In the bisphenol composition according to this embodiment, the ratio of the content of the bisphenol glycerin ether metal alkoxide to the content of the bisphenol metal alkoxide is 15 mass% or less.

The bisphenol composition according to this embodiment is a solid composition. In this specification, solid means that the composition is in a solid state in a temperature range of 15°C or higher and 40°C or higher. Such a solid bisphenol composition is preferably a paste-like, granular, or powder-like composition, and more preferably a powder-like composition.

The bisphenol composition according to this embodiment can be suitably produced by the method described in the section <2. Method for producing bisphenol composition> below. However, the method for producing the bisphenol composition is not limited to this production method, and may be, for example, a method of mixing various components.

<1-1. Bisphenol glycerin ether metal alkoxide>
The bisphenol composition according to the present embodiment contains a bisphenol glycerin ether metal alkoxide. The bisphenol composition may contain one type of bisphenol glycerin ether metal alkoxide alone, or may contain two or more types in any combination and ratio. The bisphenol glycerin ether metal alkoxide is a compound represented by the general formula (1).

In general formula (1), R's are each independently a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group.
Of these, R is preferably a hydrogen atom.

In general formula (1), each X is independently a direct bond, a hydrocarbon group having 1 to 14 carbon atoms, a halogenated hydrocarbon group having 1 to 14 carbon atoms, -SO ₂ -, -S-, -CO- or -O-.
In this specification, the hydrocarbon group may be an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a group in which an aliphatic hydrocarbon group and an aromatic hydrocarbon group are bonded. The aliphatic hydrocarbon group may be a straight-chain aliphatic hydrocarbon group, or an aliphatic hydrocarbon group containing a branched structure and/or a cyclic structure. The aromatic hydrocarbon group may be any of monocyclic, polycyclic, and condensed ring aromatic hydrocarbons, or may be a heterocyclic aromatic hydrocarbon group.

The number of carbon atoms in the hydrocarbon group having 1 to 14 carbon atoms, represented by X, is preferably 1 to 10, more preferably 1 to 6, and even more preferably 4 or less.
The hydrocarbon group having 1 to 14 carbon atoms is not particularly limited, and examples thereof include a methylene group, a methylmethylene group, a dimethylmethylene group, a diphenylmethylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a 1,3,5-trimethylpentamethylene group, a hexamethylene group, a cyclohexane-1,1-diyl group, a heptamethylene group, an octamethylene group, a nonamethylene group, a decamethylene group, and an undecamethylene group. Examples of the alkyl group include a methylene group, a dodecamethylene group, a tridecamethylene group, a tetradecamethylene group, a 1,2-xylylene group, a 1,3-xylylene group, a 1,4-xylylene group, a 1,2-phenylene group, a 1,3-phenylene group, a 1,4-phenylene group, a 1,8-naphthylene group, a 2,3-naphthylene group, a 2,6-naphthylene group, a 2,7-naphthylene group, a 9H-fluorene-9,9-diyl group, and a 4,4'-biphenylylene group.
Of these, X is preferably a dimethylmethylene group.

The halogenated hydrocarbon group having 1 to 14 carbon atoms, represented by X, is obtained by substituting a hydrogen atom bonded to a carbon atom of the above-mentioned hydrocarbon group having 1 to 14 carbon atoms with a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The hydrocarbon group portion of the halogenated hydrocarbon group has the same meaning as the above-mentioned hydrocarbon group having 1 to 14 carbon atoms, and the preferred embodiments thereof are also the same. In addition, the position of substitution with a halogen atom in the hydrocarbon group and the number of substitutions are not particularly limited.

In the general formula (1), M is each independently an alkali metal, an alkaline earth metal, magnesium, or aluminum. Examples of the alkali metal include lithium, sodium, potassium, and cesium. Examples of the alkaline earth metal include calcium, strontium, and barium.
M is preferably an alkali metal or an alkaline earth metal, more preferably an alkali metal, and even more preferably sodium.

In general formula (1), n is the valence of M, and is therefore preferably an integer of 1 to 3, more preferably 1 or 2, and even more preferably 1.

Taking all of the above into consideration, it is particularly preferable that the bisphenol glycerin ether metal alkoxide is a metal alkoxide of 2-hydroxy-1,3-bis{4-[2-(4-hydroxyphenyl)propyl]phenoxypropane, and most preferably a disodium alkoxide of 2-hydroxy-1,3-bis{4-[2-(4-hydroxyphenyl)propyl]phenoxypropane.

The bisphenol glycerin ether metal alkoxide may be a hydrate to which water molecules are added. When the bisphenol glycerin ether metal alkoxide is a hydrate, decomposition is suppressed and stability is improved.
Therefore, the bisphenol composition preferably contains water in the form of a bisphenol glycerin ether metal alkoxide, and also preferably contains water in the form of a hydrate of a bisphenol metal alkoxide, as described below. The bisphenol composition may contain water in a form other than these.

Bisphenol glycerin ether metal alkoxides can be produced by appropriately combining known organic synthesis methods, but are preferably produced by the method described in <2. Method for producing bisphenol composition> below.

The content of the bisphenol glycerin ether metal alkoxide in the bisphenol composition is not particularly limited, but the upper limit of the ratio of the content of the bisphenol glycerin ether metal alkoxide to the content of the bisphenol metal alkoxide is usually 15 mass% or less, preferably 13 mass% or less, more preferably 10 mass% or less, and even more preferably 5 mass% or less. The lower limit of the ratio is not particularly limited, and is usually more than 0 mass ppm, preferably 0.1 mass ppm or more (1.0×10 ⁻⁶ mass% or more), more preferably 10 mass ppm or more (1.0×10 ⁻³ mass% or more), even more preferably 1,000 mass ppm or more (0.1 mass% or more), and particularly preferably 10,000 mass ppm or more (1 mass% or more).
When the ratio of the content of the bisphenol glycerin ether metal alkoxide to the content of the bisphenol metal alkoxide is within the above range, a bisphenol composition with little coloration can be obtained.

<1-2. Bisphenol metal alkoxide>
The bisphenol composition according to the present embodiment contains a bisphenol metal alkoxide. The bisphenol composition may contain one type of bisphenol metal alkoxide alone, or may contain two or more types in any combination and ratio. The bisphenol metal alkoxide is not particularly limited, but is preferably a compound represented by the general formula (2).

In general formula (2), R, X, M, and n are the same as R, X, M, and n in general formula (1), and the preferred embodiments thereof are also the same.

Specific examples of bisphenols in bisphenol metal alkoxides include 4,4'-biphenol, bis(4-hydroxyphenyl)methane (i.e., bisphenol F), bis{(4-hydroxy-3,5-dimethyl)phenyl}methane, 1,1-bis(4-hydroxyphenyl)ethane (i.e., bisphenol E), 1,1-bis(4-hydroxyphenyl)-1-phenylethane (i.e., bisphenol AP), 2,2-bis(4-hydroxyphenyl)hexafluoropropane (i.e., bisphenol AF), 2,2-bis(4-hydroxyphenyl)propane (i.e., bisphenol A), 2,2-bis{(4-hydroxyphenyl)-1-phenylethane}(i.e., bisphenol AP), bisphenol AF, ... Bisphenol B, 1,1-bis(4-hydroxyphenyl)-1,1-diphenylmethane (i.e., bisphenol BP), 4,4'-isopropylidenebis(2-methyl-phenol) (i.e., bisphenol C), 2,2-bis(4-hydroxyphenyl)butane (i.e., bisphenol B), ... B), 1,1-bis(4-hydroxyphenyl)-1,1-diphenylmethane (i.e., bisphenol B), 1,1-bis(4-hydroxyphenyl)-1,1-diphenylmethane (i.e., bisphenol B), 1,1-bis(4-hydroxyphenyl)-1,1-diphenylmethane (i.e., bisphenol B), 1,1-bis(4-hydroxyphenyl)-1,1-diphenylmethane (i.e., bisphenol 1,1-bis(4-hydroxyphenyl)-4-isopropylcyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 9,9-bis(4-hydroxyphenyl)-3-isopropylcyclohexane, 9,9-bis(4-hydroxyphenyl)-3-methylbutane, 9,9-bis(4-hydroxyphenyl)-3-isopropylcyclohexane ... 4,4'-dihydroxydiphenyl)fluorene, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, α,α'-bis(4-hydroxyphenyl)-o-diisopropylbenzene, α,α'-bis(4-hydroxyphenyl)-m-diisopropylbenzene, α,α'-bis(4-hydroxyphenyl)-p-diisopropylbenzene, 1,3-bis(4-hydroxyphenyl)-5,7-dimethyladamantane, 4,4'-dihydroxydiphenyl sulfone (i.e., bisphenol S), 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl ketone, and 4,4'-dihydroxydiphenyl ether.

Of these, the bisphenol is more preferably selected from 2,2-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)-1,1-diphenylmethane, 4,4'-isopropylidenebis(2-methyl-phenol), 1,1-bis(4-hydroxyphenyl)ethane, bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxy-3-isopropylphenyl)propane, and 4,4'-dihydroxydiphenylsulfone, and even more preferably 2,2-bis(4-hydroxyphenyl)propane.

The metal of the bisphenol metal alkoxide is the metal listed as M in general formula (1). That is, the metal of the bisphenol metal alkoxide is an alkali metal, an alkaline earth metal, magnesium, or aluminum, preferably an alkali metal or an alkaline earth metal, and more preferably sodium.

Taking all of the above into consideration, it is particularly preferred that the bisphenol metal alkoxide is a metal alkoxide of 2,2-bis(4-hydroxyphenyl)propane, and it is most preferred that the bisphenol metal alkoxide is a disodium alkoxide of 2,2-bis(4-hydroxyphenyl)propane.

In this embodiment, it is also preferable that the bisphenol metal alkoxide is a compound represented by general formula (2), and that R, X, M, and n in general formula (2) are the same as R, X, M, and n in general formula (1), respectively.

The bisphenol metal alkoxide may be a hydrate to which water molecules are added. When the bisphenol metal alkoxide is a hydrate, its decomposition is suppressed, and its stability is improved.
Therefore, the bisphenol composition according to this embodiment preferably contains water in the form of a hydrate of a bisphenol metal alkoxide, and, as described above, also preferably contains water in the form of a bisphenol glycerin ether metal alkoxide.

Bisphenol metal alkoxides can be produced by appropriately combining known organic synthesis methods, but are preferably produced by the method described in <2. Method for producing bisphenol composition> below.

In this specification, bisphenol metal alkoxides are sometimes written as "bisphenol-M (M has the same meaning as M in general formula (1))". Specifically, for example, bisphenol A sodium alkoxide is sometimes written as "bisphenol A-2Na" following the above notation.

The content of the bisphenol metal alkoxide in the bisphenol composition according to this embodiment is not particularly limited, and is usually 20% by mass or more, preferably 30% by mass or more, more preferably 35% by mass or more, and even more preferably 40% by mass or more, and is usually 90% by mass or less, preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less.

<1-3. Other ingredients>
The bisphenol composition according to this embodiment may contain components other than the bisphenol metal alkoxide and the bisphenol glycerin ether metal alkoxide within the range that does not impair the effects of the present invention. When the bisphenol composition is produced by the production method according to the second embodiment of the present invention, the other components include, for example, inorganic substances such as carbon, glass, metals, and metal compounds; thermoplastic resins such as polyethylene and polypropylene; and the like.

2. Method for producing bisphenol composition
The second embodiment of the present invention is a method for producing a bisphenol composition according to the first embodiment of the present invention, and includes the following steps A to C.
Step A: A step of decomposing a cured thermosetting resin material to obtain a decomposition liquid A containing the bisphenol metal alkoxide and the bisphenol glycerin ether metal alkoxide. Step B: A step of adding water to the decomposition liquid A obtained in step A to obtain an oil-water two-phase liquid B. Step C: A step of separating the oil-water two-phase liquid B obtained in step B into oil and water, and mixing the obtained aqueous phase C with an organic solvent to obtain a suspension D.

According to this manufacturing method, the bisphenol metal alkoxide and bisphenol glycerin ether metal alkoxide in the obtained bisphenol composition are compounds derived from the monomers and curing agents of the thermosetting resin.

<2-1. Process A>
Step A is a step of decomposing a cured thermosetting resin material to obtain a decomposition liquid A containing a bisphenol metal alkoxide and a bisphenol glycerin ether metal alkoxide.

(Thermosetting resin cured product)
The cured thermosetting resin to be decomposed in step A is a thermosetting resin cured without using a curing agent or with using a curing agent.

The thermosetting resin of the cured thermosetting resin is not particularly limited, and examples thereof include copolymers of the above-mentioned bisphenol and other monomers, homopolymers of the above-mentioned epoxidized bisphenol, and copolymers of the above-mentioned epoxidized bisphenol and other monomers. Examples of such thermosetting resins include epoxy resins and phenolic resins. Among thermosetting resins, epoxy resins are resins that have epoxy groups as a constituent element, and phenolic resins are resins that have phenol, an aromatic compound, as a constituent element. The cured thermosetting resin may be a cured product of one type of thermosetting resin, or may be a cured product of two or more types of thermosetting resins.

The epoxy resin is not particularly limited, and examples thereof include diglycidyl ethers of the above bisphenols, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, and bisphenol A novolac type epoxy resins, as well as alkyl substituted derivatives, halides, and hydrogenated derivatives thereof. One type of epoxy resin may be used alone, or two or more types may be used in combination.

Examples of hardeners for thermosetting resins include acid anhydrides, amine compounds, bisphenols, phenolic compounds, and isocyanate compounds. One type of hardener may be used alone, or two or more types may be used in combination.

The curing accelerator used when curing the thermosetting resin is not particularly limited, and examples thereof include alkali metal compounds, imidazole compounds, tertiary amine compounds, quaternary ammonium salts, and organic phosphorus compounds. One type of curing accelerator may be used alone, or two or more types may be used in combination.

The thermosetting resin cured product may be mixed with other components to form a composite material, as long as the effect of the present invention is not impaired. Examples of other components include inorganic substances such as carbon, glass, metals, and metal compounds; thermoplastic resins such as polyethylene and polypropylene; and the like. Examples of the shape of the inorganic substances include fibers, particles, and foils. The fibers may be in the form of nonwoven fabric or woven fabric. In the case of woven fabric, the fibers may be a cloth material made by weaving fiber bundles, or a UD (Uni-Direction) material in which fiber bundles are arranged in one direction. The inorganic substances may contain one type alone, or two or more types.

(Disassembly method)
As a method for decomposing a cured thermosetting resin, a known method for decomposing a cured thermosetting resin or a method similar to a known method, which can produce a bisphenol metal alkoxide and a bisphenol glycerin ether metal alkoxide, can be appropriately adopted. A preferred known method is, for example, a method in which a cured thermosetting resin is brought into contact with a treatment liquid containing a decomposition catalyst and an organic solvent.

The decomposition catalyst contained in the treatment liquid is not particularly limited as long as it can decompose the thermosetting resin cured material to produce bisphenol metal alkoxide and bisphenol glycerin ether metal alkoxide. Examples of the decomposition catalyst include metal hydrides, hydroxides, borohydrides, amide compounds, fluorides, chlorides, bromides, iodides, borates, phosphates, carbonates, sulfates, nitrates, organic acid salts, and alkoxides. The metal contained in the decomposition catalyst is the same metal as the metal of the bisphenol metal alkoxide and bisphenol glycerin ether metal alkoxide to be produced, that is, alkali metals such as lithium, sodium, and potassium; magnesium; and aluminum; and is preferably an alkali metal, and more preferably sodium. Note that the decomposition catalyst may be used alone or in combination of two or more types.

Among the above compounds, the decomposition catalyst is preferably a metal alkoxide from the viewpoint of suppressing corrosion of the reaction vessel, thinning of the reaction vessel, and contamination of the product due to corrosion of the reaction vessel. Metal alkoxides are compounds in which the hydrogen atoms of the hydroxyl groups of alcohols are replaced with metals, and can be obtained by adding a metal to an alcohol.

The alcohol used to obtain the metal alkoxide is not particularly limited, and may be methanol, ethanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 2-methyl-2-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, 2,2-dimethyl-1-propanol, 1-hexanol, 2-hexanol, 3-hexanol, 2-methyl-1-pentanol, 4-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, 2-ethylhexanol, dodecanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 4-methylcyclohexanol, benzyl alcohol, phenoxyethanol, 1-(2-hydro Examples of the alcohols include (2-pyrrolidone), diacetone alcohol, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol, polyethylene glycol (molecular weight 200 to 400), 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, glycerin, and dipropylene glycol. These alcohols may be used alone or in combination of two or more.

The metal alkoxide may be in a solid state or a solution state. From the viewpoint of decomposition efficiency of a thermosetting resin cured material, the metal alkoxide is preferably selected from sodium methoxide, sodium ethoxide, sodium propoxide, sodium isopropoxide, sodium benzyl alkoxide (sodium benzyl oxide), potassium methoxide, potassium ethoxide, potassium propoxide, isopropoxide, and potassium benzyl alkoxide (potassium benzyl oxide).

These alkali metal alkoxides may be used alone or in combination of two or more.

The organic solvent is not particularly limited, and examples thereof include alcohol-based solvents, ether-based solvents, and aromatic solvents.

The alcohol solvent is not particularly limited, and examples thereof include 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 2-methyl-2-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, 2,2-dimethyl-1-propanol, 1-hexanol, 2-hexanol, 3-hexanol, 2-methyl-1-pentanol, 4-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, 2-ethylhexanol, dodecanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 4-methylcyclohexanol, benzyl alcohol, and phenoxyethanol. The alcohol-based solvent may be used alone or in combination of two or more.

The ether-based solvent is not particularly limited, and examples thereof include diethyl ether, dipropyl ether, dibutyl ether, butyl methyl ether, butyl ethyl ether, diisoamyl ether, hexyl methyl ether, octyl methyl ether, cyclopentyl methyl ether, and dicyclopentyl ether. One type of ether-based solvent may be used alone, or two or more types may be used in combination.

The aromatic solvent is not particularly limited, and examples thereof include benzene, toluene, xylene, alkylbenzenes such as trimethylbenzene and ethylbenzene, and alkylnaphthalenes such as methylnaphthalene, ethylnaphthalene, and dimethylnaphthalene. Aromatic solvents may be used alone or in combination of two or more.

In addition, one or more types of alcohol-based solvents may be used in combination with one or more types of ether-based solvents, one or more types of alcohol-based solvents may be used in combination with one or more types of aromatic solvents, one or more types of ether-based solvents may be used in combination with one or more types of aromatic solvents, or one or more types of alcohol-based solvents, one or more types of ether-based solvents, and one or more types of aromatic solvents may be used in combination.

Of these, alcohol-based solvents are preferred because they have excellent solubility in decomposition products of cured thermosetting resins. In addition, when a metal alkoxide is used as the decomposition catalyst, it is preferable that at least a portion of the organic solvent contains the same alcohol-based solvent as the raw material alcohol of the metal alkoxide.

In addition, from the viewpoint that heating is required for decomposing the cured thermosetting resin material, the organic solvent is preferably an organic solvent having a boiling point of 100° C. or higher under atmospheric pressure, more preferably 120° C. or higher, and particularly preferably 150° C. or higher.
From this viewpoint, benzyl alcohol (boiling point: 205° C.) is a preferred organic solvent.

The treatment liquid may further contain other components in addition to the decomposition catalyst and the organic solvent, if necessary, such as a surfactant and a low-viscosity solvent.

From the viewpoint of improving the decomposition efficiency of the cured thermosetting resin material, the concentration of the decomposition catalyst in the treatment liquid is preferably 0.001 mol/L or more and 100 mol/L or less, more preferably 0.005 mol/L or more and 50 mol/L or less, and even more preferably 0.01 mol/L or more and 20 mol/L or less. The higher the concentration of the decomposition catalyst, the more efficiently the cured thermosetting resin material can be decomposed. The lower the concentration of the decomposition catalyst, the more efficiently the cured thermosetting resin material can be decomposed without increasing the viscosity of the treatment liquid.

When preparing the treatment liquid, the decomposition catalyst may be mixed with the organic solvent in a solid state or in a solution state. There is no need to heat the treatment liquid, and the treatment liquid can be prepared by mixing the organic solvent and the decomposition catalyst at room temperature of about 5 to 35°C.

The reaction vessel used when contacting the treatment liquid with the cured thermosetting resin is preferably a vessel containing stainless steel from the viewpoint of corrosion prevention. Stainless steel is not particularly limited, but examples include austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, austenitic-ferritic stainless steel, and precipitation hardening stainless steel, and is preferably austenitic stainless steel, particularly preferably SUS304, SUS316, or SUS316L.

The reaction vessel is not particularly limited as long as it is capable of contacting the treatment liquid with the cured thermosetting resin material. As long as the vessel can be used as a decomposition tank, it may be box-shaped, cylindrical, mesh-like cage-shaped, or made of a porous material.
The ratio (filling rate) of the volume of the cured thermosetting resin placed in the container to the volume of the container is preferably within the range of 5% to 25% from the viewpoint of dissolution efficiency.

The bisphenol glycerin ether metal alkoxide produced by decomposition of the cured thermosetting resin is further decomposed to become a bisphenol metal alkoxide. Therefore, the content of bisphenol metal alkoxide in the bisphenol composition and the ratio of the content of bisphenol glycerin ether metal alkoxide to the content of bisphenol metal alkoxide vary depending on the heating temperature and contact time of the treatment liquid when the treatment liquid is brought into contact with the cured thermosetting resin. In other words, the decomposition rate increases when the heating temperature is increased, and the decomposition progresses further when the contact time is extended. Therefore, the heating temperature and contact time may be appropriately selected from the following ranges depending on the desired content of bisphenol metal alkoxide and the ratio of the content of bisphenol glycerin ether metal alkoxide to the desired content of bisphenol metal alkoxide.

The heating temperature of the treatment liquid is preferably 100°C or higher, more preferably 130°C or higher, and particularly preferably 150°C or higher, from the viewpoint of improving the decomposition efficiency of the cured thermosetting resin. On the other hand, this temperature is preferably 300°C or lower, particularly preferably 250°C or lower, from the viewpoint of suppressing denaturation of the solvent and decomposition products.

The contact time between the treatment liquid and the cured thermosetting resin varies depending on the type of thermosetting resin, the type and concentration of the decomposition catalyst and organic solvent used, and the treatment temperature, but typically 50% or more by weight of the cured thermosetting resin can be decomposed in about 2 to 50 hours.

<2-2. Process B>
In step B, water is added to the decomposition liquid A obtained in step A to obtain an oil-water two-phase liquid B. In this step, the bisphenol metal alkoxide and the bisphenol glycerin ether metal alkoxide contained in the decomposition liquid A are dissolved in water. On the other hand, decomposition products of the cured thermosetting resin other than bisphenol metal alkoxide and bisphenol glycerin ether metal alkoxide are insoluble or poorly soluble in water, and therefore most of them are selectively extracted into the oil phase. Therefore, according to the production method of the present embodiment, the bisphenol metal alkoxide and the bisphenol glycerin ether metal alkoxide are selectively recovered from the decomposition products of the cured thermosetting resin. It becomes possible.

The water to be added to the decomposition liquid A is not particularly limited, and may be, for example, tap water, distilled water, ion-exchanged water, ultrapure water, or the like.
Although water may be added to the decomposition liquid A in the form of an acid aqueous solution in which an acid is dissolved, it is preferable to add water that is substantially free of acid in order to avoid conversion to bisphenol metal alkoxide and bisphenol glycerin ether metal alkoxide. Note that "water that is substantially free of acid" means that it is not an acid aqueous solution in which acid has been intentionally added to water, and is not intended to exclude water that inevitably contains acid (for example, water in which carbon dioxide in the atmosphere has been dissolved).
When the water contains an acid, the tolerable amount of the acid is preferably an amount that does not neutralize the aqueous phase of the oil-water two-phase liquid B. A specific tolerable amount of the acid is an amount that makes the pH (25° C.) of the aqueous phase of the oil-water two-phase liquid B preferably 3.0 or more, more preferably 4.0 or more, and even more preferably 5.0 or more.

The amount of water to be added to the decomposition liquid A is not particularly limited as long as it is an amount that can sufficiently extract the bisphenol metal alkoxide and bisphenol glycerin ether metal alkoxide produced in step A, and when the water contains an acid, it is an amount that can bring the pH of the aqueous phase of the oil-water two-phase liquid B into the above range. Specifically, the weight ratio of water to the decomposition liquid is preferably 0.001 to 1000, more preferably 0.010 to 100, and even more preferably 0.050 to 10. If the amount of water is equal to or more than the lower limit, the bisphenol metal alkoxide and bisphenol glycerin ether metal alkoxide can be sufficiently extracted. Furthermore, if the amount of the organic solvent is equal to or less than the upper limit, a large-sized container is not required for the extraction of the bisphenol metal alkoxide and bisphenol glycerin ether metal alkoxide, and high production efficiency can be ensured.

Step B may be a step of obtaining a decomposition liquid A' by removing insoluble matters by solid-liquid separation of the decomposition liquid A obtained in step A, and obtaining an oil-water two-phase liquid B by adding water to the decomposition liquid A'. The insoluble matters are, for example, matters that remain in the decomposition liquid A without being decomposed together with the thermosetting resin cured product in step A, and do not dissolve in either the aqueous phase or the organic phase of the oil-water two-phase liquid B. Examples of the insoluble matters include inorganic matters and thermoplastic resins contained in the thermosetting resin cured product; other impurities; and the like. When the decomposition liquid A contains insoluble matters, the insoluble matters are removed by performing step B as described above, and the content of the bisphenol metal alkoxide and the bisphenol glycerin ether metal alkoxide in the bisphenol composition can be increased.

<2-3. Process C>
Step C is a step of separating the oil-water two-phase liquid B obtained in step B into oil and water, and mixing the resulting aqueous phase C with an organic solvent to obtain a suspension D. Since the bisphenol metal alkoxide and the bisphenol glycerin ether metal alkoxide are extracted into the aqueous phase, an aqueous solution C containing these can be obtained by separating the oil from the water and recovering the aqueous phase. By mixing with the solvent, the bisphenol metal alkoxide and the bisphenol glycerin ether metal alkoxide dissolved in the aqueous phase C are precipitated by the organic solvent, which is a poor solvent, to obtain a suspension D.

The organic solvent used in step C is not particularly limited as long as it is a solvent in which the bisphenol metal alkoxide and the bisphenol glycerin ether metal alkoxide have low solubility and are soluble in water, and examples thereof include ketone solvents having 1 to 8 carbon atoms, such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; alcohol solvents having 1 to 6 carbon atoms, such as methanol, ethanol, propanol, isopropanol, butanol, and isobutanol; and ether solvents having 1 to 6 carbon atoms, such as dimethyl ether, diethyl ether, and dipropyl ether. Of these, the organic solvent is preferably a ketone solvent, and more preferably acetone, in terms of being able to efficiently precipitate the bisphenol metal alkoxide and the bisphenol glycerin ether metal alkoxide.

The method of mixing the aqueous phase C with the organic solvent in step C is not particularly limited, but from the viewpoint of reducing the amount of organic solvent used and precipitating the bisphenol metal alkoxide and the bisphenol glycerin ether metal alkoxide in a short time, it is preferable to mix the aqueous phase C by dropping it into the organic solvent, to distill off the water in the aqueous phase C by reduced pressure distillation or the like and then mix it with the organic solvent, or to distill off the water in the aqueous phase C by reduced pressure distillation or the like and then drop it into the organic solvent.

In step C, the weight ratio of the organic solvent to the aqueous phase C is preferably 0.001 to 1000, more preferably 0.010 to 100, and even more preferably 0.050 to 10. If the amount of the organic solvent is equal to or greater than the lower limit, the bisphenol metal alkoxide and the bisphenol glycerin ether metal alkoxide can be sufficiently precipitated. If the amount of the organic solvent is equal to or less than the upper limit, a large vessel is not required for the precipitation of the bisphenol metal alkoxide and the bisphenol glycerin ether metal alkoxide, and high production efficiency can be ensured.

The temperature of the system in which the organic solvent and aqueous phase C are mixed is preferably equal to or lower than the boiling point of the organic solvent, more preferably equal to or lower than 70°C, and even more preferably equal to or lower than 50°C.

<2-4. Process D>
Step D is a step of subjecting the suspension D obtained in step D to solid-liquid separation and recovering the solid phase. The suspension D contains the bisphenol metal ions precipitated by mixing with the organic solvent in step C. Since alkoxide and bisphenol glycerin ether metal alkoxide are present, a solid phase containing bisphenol metal alkoxide and bisphenol glycerin ether metal alkoxide can be recovered as a bisphenol composition by solid-liquid separation.

The method of solid-liquid separation in step D is not particularly limited, and methods such as filtration, decantation, gravity separation, and centrifugation can be used. Filtration may be performed at normal pressure, but the time required for separation can be shortened by performing filtration under increased or reduced pressure.

3. Method for producing epoxy resin
The third embodiment of the present invention is a method for producing an epoxy resin, comprising the steps of contacting the bisphenol composition according to the first embodiment of the present invention with epihalohydrin, and reacting the bisphenol metal alkoxide in the bisphenol composition with the epihalohydrin. Examples of the epihalohydrin include epichlorohydrin and epibromohydrin, and epichlorohydrin is preferred.
Hereinafter, the epoxy resin produced by the production method according to this embodiment may be referred to as "recycled epoxy resin."

In the manufacturing method according to this embodiment, a recycled epoxy resin can be manufactured in accordance with a known one-step method for manufacturing recycled epoxy resin. The one-step method for manufacturing recycled epoxy resin is a method for obtaining recycled epoxy resin by reacting a hydroxy compound raw material with epihalohydrin. In the manufacturing method according to this embodiment, at least a part of the hydroxy compound raw material is the bisphenol metal alkoxide and bisphenol glycerin ether metal alkoxide contained in the bisphenol composition according to the first embodiment of the present invention. In addition to the bisphenol metal alkoxide and bisphenol glycerin ether metal alkoxide, the hydroxy compound raw material may also contain a polyhydric hydroxy compound (hereinafter, sometimes referred to as "other polyhydric hydroxy compound").

Here, "other polyhydric hydroxy compounds" is a general term for bisphenols and other dihydric or higher alcohol compounds. In the one-stage method for producing recycled epoxy resins, the "hydroxy compound raw material" is the total hydroxy compound including bisphenol metal alkoxide, bisphenol glycerin ether metal alkoxide, and other polyhydric hydroxy compounds used as needed.

Other polyhydric hydroxy compounds include various polyhydric phenols such as bisphenol A, tetramethyl bisphenol A, bisphenol F, tetramethyl bisphenol F, bisphenol S, bisphenol C, bisphenol AD, bisphenol AF, hydroquinone, resorcin, methyl resorcin, biphenol, tetramethyl biphenol, dihydroxynaphthalene, dihydroxydiphenyl ether, thiodiphenols, phenol novolac resins, cresol novolac resins, phenol aralkyl resins, biphenyl aralkyl resins, naphthol aralkyl resins, terpene phenol resins, dicyclopentadiene phenol resins, bisphenol A novolac resins, naphthol novolac resins, brominated bisphenol A, brominated phenol novolac resins, and the like; various phenols and benzaldehyde, hydroxybenzaldehyde, and the like. Examples include polyhydric phenol resins obtained by condensation reactions with various aldehydes such as aldehyde, crotonaldehyde, and glyoxal; polyhydric phenol resins obtained by condensation reactions between xylene resin and phenols; various phenol resins such as co-condensation resins of heavy oil or pitches, phenols, and formaldehydes; chain aliphatic diols such as ethylene glycol, trimethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, and 1,6-hexanediol; cyclic aliphatic diols such as cyclohexanediol and cyclodecanediol; polyalkylene ether glycols such as polyethylene ether glycol, polyoxytrimethylene ether glycol, and polypropylene ether glycol; and the like.

During the reaction, the bisphenol composition and other polyhydric hydroxy compounds are dissolved in epihalohydrin to form a homogeneous solution.

The amount of epihalohydrin used is preferably an amount equivalent to usually 1.0 to 14.0 equivalents, and particularly 2.0 to 10.0 equivalents, per equivalent of the total hydroxyl groups in the hydroxy compound raw material (all hydroxy compounds). If the amount of epihalohydrin is equal to or greater than the lower limit, it is preferable because it is easier to control the polymerisation reaction and the resulting recycled epoxy resin can have an appropriate epoxy equivalent. On the other hand, if the amount of epihalohydrin is equal to or less than the upper limit, production efficiency tends to improve, which is preferable.

Next, while stirring the solution, an alkali metal hydroxide is added in the form of a solid or an aqueous solution in an amount corresponding to usually 0.1 to 3.0 equivalents, preferably 0.8 to 2.0 equivalents per equivalent of the total hydroxyl groups of the hydroxy compound raw material, to cause a reaction. When the amount of the alkali metal hydroxide added is equal to or greater than the lower limit, the unreacted hydroxyl groups and the generated epoxy resin are less likely to react, making it easier to control the polymerizing reaction, which is preferred. When the amount of the alkali metal hydroxide added is equal to or less than the upper limit, impurities due to side reactions are less likely to be generated, which is preferred. The alkali metal hydroxide used here is usually sodium hydroxide or potassium hydroxide.

This reaction can be carried out under normal pressure or reduced pressure, and the reaction temperature is preferably 20 to 200°C, more preferably 40 to 150°C. A reaction temperature equal to or higher than the lower limit is preferred because the reaction is easier to proceed and easier to control. A reaction temperature equal to or lower than the upper limit is preferred because side reactions are less likely to proceed, and it is particularly easy to reduce the amount of polymer.

This reaction is also carried out while dehydrating the reaction liquid by azeotroping it while maintaining a specified temperature as necessary, cooling the volatilizing steam, separating the condensate obtained, and returning the oil with the moisture removed to the reaction system. In order to prevent a rapid reaction, the alkali metal hydroxide is added intermittently or continuously in small amounts, preferably over a period of 0.1 to 24 hours, more preferably over a period of 0.5 to 10 hours. If the addition time of the alkali metal hydroxide is equal to or greater than the above lower limit, the reaction can be prevented from proceeding too rapidly, making it easier to control the reaction temperature, which is preferable. If the addition time is equal to or less than the above upper limit, it is easier to reduce the amount of polymer, which is preferable.

After the reaction is complete, the insoluble by-product salts are removed by filtration or by washing with water, and the unreacted epihalohydrin can then be removed by heating and/or distillation under reduced pressure.

In addition, in this reaction, catalysts such as quaternary ammonium salts such as tetramethylammonium chloride and tetraethylammonium bromide; tertiary amines such as benzyldimethylamine and 2,4,6-tris(dimethylaminomethyl)phenol; imidazoles such as 2-ethyl-4-methylimidazole and 2-phenylimidazole; phosphonium salts such as ethyltriphenylphosphonium iodide; and phosphines such as triphenylphosphine may be used.

In addition, in this reaction, inert organic solvents such as alcohols such as ethanol and isopropanol; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; ethers such as dioxane and ethylene glycol dimethyl ether; glycol ethers such as methoxypropanol; and aprotic polar solvents such as dimethyl sulfoxide and dimethylformamide may be used.

[Production of recycled epoxy resin with reduced total chlorine content]
When it is necessary to reduce the total chlorine content of the regenerated epoxy resin obtained as described above, a regenerated epoxy resin having a reduced total chlorine content can be produced by reaction with an alkali.

An organic solvent for dissolving the recycled epoxy resin may be used for the reaction with the alkali. There are no particular limitations on the organic solvent used in the reaction, but it is preferable to use a ketone-based organic solvent in terms of production efficiency, handling, workability, etc. Also, from the viewpoint of further reducing the amount of hydrolyzable chlorine, an aprotic polar solvent may be used.

Examples of ketone-based organic solvents include ketone-based solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Methyl isobutyl ketone is particularly preferred because of its effectiveness and ease of post-treatment. These may be used alone or in combination of two or more.

Examples of aprotic polar solvents include dimethyl sulfoxide, diethyl sulfoxide, dimethyl sulfone, sulfolane, dimethylformamide, dimethylacetamide, and hexamethylphosphoramide. These may be used alone or in combination of two or more. Among these aprotic polar solvents, dimethyl sulfoxide is preferred because it is easily available and has excellent effects.

The amount of the above solvent used is such that the concentration of the recycled epoxy resin in the liquid subjected to the alkali treatment is usually 1 to 95% by mass, preferably 5 to 80% by mass.

As the alkali, a solid or solution of an alkali metal hydroxide can be used. Examples of the alkali metal hydroxide include potassium hydroxide and sodium hydroxide, and sodium hydroxide is preferred. The alkali metal hydroxide may be dissolved in an organic solvent or water. Preferably, the alkali metal hydroxide is used as a solution in an aqueous solvent or an organic solvent.

The amount of alkali metal hydroxide used is preferably 0.01 to 20.0 parts by mass or less per 100 parts by mass of recycled epoxy resin, calculated as the solid content of the alkali metal hydroxide. More preferably, it is 0.10 to 10.0 parts by mass. If the amount of alkali metal hydroxide used is less than the lower limit, the effect of reducing the total chlorine content is low, and if it is more than the upper limit, a large amount of polymer is produced, resulting in a low yield.

The reaction temperature is preferably 20 to 200° C., more preferably 40 to 150° C., and the reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 10 hours.
After the reaction, excess alkali metal hydroxide and secondary salts can be removed by washing with water or the like, and the organic solvent can be further removed by heating and/or distillation under reduced pressure and/or steam distillation.

4. Method for producing epoxy resin
The fourth embodiment of the present invention is a method for producing an epoxy resin, comprising a step of reacting the epoxy resin obtained by the production method according to the third embodiment of the present invention with a polyhydric hydroxy compound. The polyhydric hydroxy compound in this embodiment is a general term for bisphenol and other dihydric or higher alcohols.
Hereinafter, the epoxy resin produced by the production method according to this embodiment may be referred to as "recycled epoxy resin."

In the manufacturing method according to this embodiment, recycled epoxy resin can be manufactured in accordance with the known two-stage method for manufacturing recycled epoxy resin. The two-stage method for manufacturing recycled epoxy resin includes a step of reacting an epoxy resin raw material with a polyhydric hydroxy compound raw material. In this embodiment, at least a part of the epoxy resin raw material is an epoxy resin obtained by the manufacturing method according to the third embodiment of the present invention.

That is, the method for producing recycled epoxy resin by the two-stage method is a method for reacting an epoxy resin raw material containing an epoxy resin obtained by the production method according to the third embodiment of the present invention with a polyhydric hydroxy compound raw material containing a polyhydric hydroxy compound.

The epoxy resin raw material may contain other epoxy resins as necessary in addition to the epoxy resin obtained by the manufacturing method according to the third embodiment of the present invention.

The other epoxy resins are as described below in the method for producing a cured epoxy resin according to the fifth embodiment of the present invention, and the polyhydric hydroxy compounds are the same as the other polyhydric hydroxy compounds in the method for producing a recycled epoxy resin according to the third embodiment of the present invention.

The amount of recycled epoxy resin in the epoxy resin raw material is not particularly limited, but a high recycled epoxy resin content is more environmentally friendly, so 1 to 100% by mass is preferred, and 10 to 100% by mass is more preferred.

In the two-stage reaction, the amounts of epoxy resin raw material and polyhydric hydroxy compound raw material used are preferably such that the equivalent ratio (epoxy group equivalent):(hydroxyl group equivalent) is 1:0.1-2.0. More preferably, it is 1:0.2-1.2. If this equivalent ratio is within the above range, it is preferable because it is easy to proceed with high molecular weight and more epoxy group terminals can be left.

In addition, a catalyst may be used in the reaction by the two-stage method. The catalyst may be any compound that has catalytic ability to promote the reaction between the epoxy group and the phenolic hydroxyl group or the alcoholic hydroxyl group. Examples of the catalyst include alkali metal compounds, organic phosphorus compounds, tertiary amines, quaternary ammonium salts, cyclic amines, imidazoles, etc. Among these, quaternary ammonium salts are preferred. The catalyst may be used alone or in combination of two or more types. The amount of catalyst used is usually 0.001 to 10% by mass based on the epoxy resin raw material.

In the two-stage reaction, a solvent may be used, and any solvent that dissolves the epoxy resin raw material may be used. Examples include aromatic solvents, ketone solvents, amide solvents, and glycol ether solvents. Only one type of solvent may be used, or two or more types may be used in combination. The resin concentration in the solvent is preferably 10 to 95% by mass. More preferably, it is 20 to 80% by mass. If a highly viscous product is produced during the reaction, additional solvent may be added to continue the reaction. After the reaction is completed, the solvent may be removed or further added as necessary.

In the two-stage reaction, the reaction temperature is preferably 20 to 250°C, more preferably 50 to 200°C. If the reaction temperature is above the upper limit, the epoxy resin produced may deteriorate. If the reaction temperature is below the lower limit, the reaction may not proceed sufficiently. The reaction time is usually 0.1 to 24 hours, preferably 0.5 to 12 hours.

5. Method for producing epoxy resin cured product
The fifth embodiment of the present invention is a method for producing a cured epoxy resin product, which includes a step of curing an epoxy resin composition containing a curing agent and a recycled epoxy resin obtained by the production method according to the third or fourth embodiment of the present invention. It is also possible to obtain a composite material again by further blending an inorganic substance with the epoxy resin composition and curing the epoxy resin composition. In this way, according to this embodiment, a new chemical recycling method can be established.

In this embodiment, the epoxy resin composition may be appropriately blended with other epoxy resins, curing agents, curing accelerators, inorganic fillers, coupling agents, etc., other than the recycled epoxy resin obtained by the manufacturing method according to the third or fourth embodiment of the present invention, as necessary.

The content of recycled epoxy resin in the epoxy resin composition is not particularly limited. Since a high content of recycled epoxy resin is environmentally friendly, the recycled epoxy resin is preferably 40 parts by mass or more, more preferably 60 parts by mass or more, per 100 parts by mass of all epoxy resin components in the epoxy resin composition. When other epoxy resins are included, the recycled epoxy resin can be 40 to 99 parts by mass, 60 to 99 parts by mass, etc., per 100 parts by mass of all epoxy resin components in the epoxy resin composition. Note that "total epoxy resin components" corresponds to the amount of all epoxy resins contained in the epoxy resin composition, and is the sum of the recycled epoxy resin and other epoxy resins used as necessary.

(Hardening agent)
The curing agent contained in the epoxy resin composition refers to a substance that contributes to the crosslinking reaction and/or the chain extension reaction between epoxy groups of the epoxy resin. In this embodiment, even a substance that is usually called a "curing accelerator" is considered to be a curing agent as long as it contributes to the crosslinking reaction and/or the chain extension reaction between epoxy groups of the epoxy resin.

In the epoxy resin composition, the content of the curing agent is preferably 0.1 to 1,000 parts by mass per 100 parts by mass of the total epoxy resin components. More preferably, it is 500 parts by mass or less.

There are no particular limitations on the curing agent, and any agent generally known as an epoxy resin curing agent can be used. Examples include amine-based curing agents such as phenol-based curing agents, aliphatic amines, polyetheramines, alicyclic amines, and aromatic amines; acid anhydride-based curing agents; amide-based curing agents; tertiary amines; imidazoles; and the like. The curing agent may be used alone or in combination of two or more. When using two or more types of curing agents in combination, they may be mixed in advance to prepare a mixed curing agent before use, or when mixing the components of the recycled epoxy resin obtained by the manufacturing method according to the third or fourth embodiment of the present invention and other epoxy resins, each component of the curing agent may be added separately and mixed simultaneously.

Specific examples of phenol-based hardeners include bisphenol A, tetramethylbisphenol A, bisphenol F, tetramethylbisphenol F, bisphenol C, bisphenol S, bisphenol AD, bisphenol AF, hydroquinone, resorcin, methylresorcin, biphenol, tetramethylbiphenol, dihydroxynaphthalene, dihydroxydiphenyl ether, thiodiphenols, phenol novolac resin, cresol novolac resin, phenol aralkyl resin, biphenyl aralkyl resin, naphthol aralkyl resin, terpene phenol resin, dicyclopentadiene phenol resin, bisphenol A novolac resin, trisphenolmethane type resin, naphthol novolac resin, and brominated bisphenol A. , brominated phenol novolac resins, and other polyhydric phenols; polyhydric phenol resins obtained by condensation reactions of various phenols with various aldehydes such as benzaldehyde, hydroxybenzaldehyde, crotonaldehyde, and glyoxal; polyhydric phenol resins obtained by condensation reactions of xylene resins and phenols; co-condensation resins of heavy oils or pitches, phenols, and formaldehydes; phenol-benzaldehyde-xylylene dimethoxide polycondensates, phenol-benzaldehyde-xylylene dihalide polycondensates, phenol-benzaldehyde-4,4'-dimethoxide biphenyl polycondensates, and phenol-benzaldehyde-4,4'-dihalide biphenyl polycondensates.

These phenolic hardeners may be used alone or in any combination of two or more in any ratio.

The amount of the phenol-based curing agent is preferably 0.1 to 1,000 parts by mass, and more preferably 500 parts by mass or less, per 100 parts by mass of the total epoxy resin components in the epoxy resin composition.

Examples of amine-based curing agents (excluding tertiary amines) include aliphatic amines, polyether amines, alicyclic amines, and aromatic amines.

Examples of aliphatic amines include ethylenediamine, 1,3-diaminopropane, 1,4-diaminopropane, hexamethylenediamine, and 2,5-dimethylhexamethylenediamine.
Examples include trimethylhexamethylenediamine, diethylenetriamine, iminobispropylamine, bis(hexamethylene)triamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, N-hydroxyethylethylenediamine, and tetra(hydroxyethyl)ethylenediamine.

Examples of polyetheramines include triethylene glycol diamine, tetraethylene glycol diamine, diethylene glycol bis(propylamine), polyoxypropylene diamine, and polyoxypropylene triamines.

Examples of alicyclic amines include isophorone diamine, methacenediamine, N-aminoethylpiperazine, bis(4-amino-3-methyldicyclohexyl)methane, bis(aminomethyl)cyclohexane, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro(5,5)undecane, and norbornene diamine.

Examples of aromatic amines include tetrachloro-p-xylylenediamine, m-xylylenediamine, p-xylylenediamine, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, 2,4-diaminoanisole, 2,4-toluenediamine, 2,4-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 4,4'-diamino-1,2-diphenylethane, 2,4-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, m-aminophenol, m-aminobenzylamine, benzyldimethylamine, 2-(dimethylaminomethyl)phenol, triethanolamine, methylbenzylamine, α-(m-aminophenyl)ethylamine, α-(p-aminophenyl)ethylamine, diaminodiethyldimethyldiphenylmethane, and α,α'-bis(4-aminophenyl)-p-diisopropylbenzene.

The amine-based curing agents listed above may be used alone or in any combination of two or more in any ratio.

The above amine-based curing agent is preferably used so that the equivalent ratio of the functional groups in the curing agent to the epoxy groups in all epoxy resin components contained in the epoxy resin composition is in the range of 0.1 to 2.0. More preferably, the equivalent ratio is in the range of 0.8 to 1.2. If it is within this range, it is preferable because unreacted epoxy groups and functional groups of the curing agent are less likely to remain.

Examples of tertiary amines include 1,8-diazabicyclo(5,4,0)undecene-7, triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol.
The tertiary amines listed above may be used alone or in any combination of two or more kinds in any blend ratio.

The above tertiary amines are preferably used so that the equivalent ratio of the functional groups in the curing agent to the epoxy groups in all epoxy resin components contained in the epoxy resin composition is in the range of 0.1 to 2.0. More preferably, the equivalent ratio is in the range of 0.8 to 1.2. This range is preferable because unreacted epoxy groups and functional groups of the curing agent are less likely to remain.

Acid anhydride-based hardeners include acid anhydrides and modified acid anhydrides.

Examples of the acid anhydride include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, dodecenylsuccinic anhydride, polyadipic anhydride, polyazelaic anhydride, polysebacic anhydride, poly(ethyloctadecanedioic) anhydride, poly(phenylhexadecanedioic) anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, methylhimic anhydride, trialkyltetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylhimic anhydride, trialkyltetrahydrophthalic anhydride, methylhexa ... ethylcyclohexene dicarboxylic anhydride, methylcyclohexene tetracarboxylic anhydride, ethylene glycol bistrimellitate dianhydride, HET anhydride, Nadic anhydride, methylnadic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexane-1,2-dicarboxylic anhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride, and 1-methyl-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride.

Examples of modified acid anhydrides include those obtained by modifying the above-mentioned acid anhydrides with glycols. Examples of glycols that can be used for modification include alkylene glycols such as ethylene glycol, propylene glycol, and neopentyl glycol; and polyether glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol. Furthermore, copolymer polyether glycols of two or more of these glycols and/or polyether glycols can also be used.

The above-listed acid anhydride curing agents may be used alone or in any combination of two or more in any amount.

When an acid anhydride curing agent is used, it is preferable to use it so that the equivalent ratio of the functional groups in the curing agent to the epoxy groups in all epoxy resin components in the epoxy resin composition is in the range of 0.1 to 2.0. More preferably, the equivalent ratio is in the range of 0.8 to 1.2. If it is within this range, it is preferable because unreacted epoxy groups and functional groups of the curing agent are less likely to remain.

Examples of the amide-based curing agent include dicyandiamide and its derivatives, and polyamide resins.
The amide-based curing agent may be used alone or in any combination and ratio of two or more kinds.
When an amide-based curing agent is used, it is preferable to use the amide-based curing agent in an amount of 0.1 to 20 mass % based on the total amount of all epoxy resin components and the amide-based curing agent in the epoxy resin composition.

Examples of imidazoles include 2-phenylimidazole, 2-ethyl-4(5)-methylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyano-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2′-methylimidazolyl- Examples of the imidazoles include 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and adducts of epoxy resins and the above imidazoles. Since imidazoles have catalytic activity, they can generally be classified as curing accelerators, but in the present invention, they are classified as curing agents.
The imidazoles listed above may be used alone or in any combination and ratio of two or more kinds.

When using imidazoles, it is preferable to use them in an amount of 0.1 to 20 mass% based on the total amount of all epoxy resin components and imidazoles in the epoxy resin composition.

In addition to the above-mentioned curing agents, other curing agents can be used in the epoxy resin composition. There are no particular limitations on the other curing agents that can be used in the epoxy resin composition, and any curing agent generally known as a curing agent for epoxy resins can be used.
These other curing agents may be used alone or in combination of two or more.

(Other epoxy resins)
The epoxy resin composition may further contain other epoxy resins (other epoxy resins) in addition to the recycled epoxy resin obtained by the production method according to the third or fourth embodiment of the present invention. By containing other epoxy resins, various physical properties can be improved.

Other epoxy resins that can be used in the epoxy resin composition include all epoxy resins other than the recycled epoxy resin obtained by the manufacturing method according to the third or fourth embodiment of the present invention. Specific examples include bisphenol A type epoxy resin, bisphenol C type epoxy resin, trisphenolmethane type epoxy resin, anthracene type epoxy resin, phenol-modified xylene resin type epoxy resin, bisphenol cyclododecyl type epoxy resin, bisphenol diisopropylidene resorcin type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, bisphenol AF type epoxy resin, hydroquinone type epoxy resin, methyl hydroquinone type epoxy resin, dibutyl hydroquinone type epoxy resin, resorcin type epoxy resin, methyl resorcin type epoxy resin, biphenol type epoxy resin, tetramethyl biphenol type epoxy resin, tetramethyl bisphenol F type epoxy resin, dihydroxy diphenyl ether type epoxy resin, epoxy resin derived from thiodiphenols, dihydroxy naphthalene type epoxy resin, dihydroxy anthracene type epoxy resin, dihydroxy dihydro anthracene type epoxy resin, dicyclopentadiene type epoxy resin, dihydro Examples of the epoxy resins include epoxy resins derived from hydroxystilbenes, phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A novolac type epoxy resins, naphthol novolac type epoxy resins, phenol aralkyl type epoxy resins, naphthol aralkyl type epoxy resins, biphenyl aralkyl type epoxy resins, terpene phenol type epoxy resins, dicyclopentadiene phenol type epoxy resins, epoxy resins derived from a phenol-hydroxybenzaldehyde condensate, epoxy resins derived from a phenol-crotonaldehyde condensate, epoxy resins derived from a phenol-glyoxal condensate, epoxy resins derived from a co-condensation resin of heavy oil or pitches, phenols, and formaldehydes, epoxy resins derived from diaminodiphenylmethane, epoxy resins derived from aminophenols, epoxy resins derived from xylylenediamine, epoxy resins derived from methylhexahydrophthalic acid, and epoxy resins derived from dimer acids. These may be used alone or in any combination of two or more in any ratio.

When the epoxy resin composition contains the above-mentioned other epoxy resins, the content thereof is preferably 1 to 60 parts by mass, and more preferably 40 parts by mass or less, per 100 parts by mass of the total epoxy resin components in the composition.

(Cure Accelerator)
The epoxy resin composition preferably contains a curing accelerator. By containing the curing accelerator, it is possible to shorten the curing time and lower the curing temperature, and it is possible to easily obtain a desired cured product.

The curing accelerator is not particularly limited, but specific examples include organic phosphines, phosphorus compounds such as phosphonium salts, tetraphenylboron salts, organic acid dihydrazides, and boron halide amine complexes.

Phosphorus compounds that can be used as curing accelerators include triphenylphosphine, diphenyl(p-tolyl)phosphine, tris(alkylphenyl)phosphine, tris(alkoxyphenyl)phosphine, tris(alkyl-alkoxyphenyl)phosphine, tris(dialkylphenyl)phosphine, tris(trialkylphenyl)phosphine, tris(tetraalkylphenyl)phosphine, tris(dialkoxyphenyl)phosphine, tris(trialkoxyphenyl)phosphine, tris(tetraalkoxyphenyl)phosphine, trialkylphosphine Examples include organic phosphines such as phenylphosphine, dialkylarylphosphine, and alkyldiarylphosphine; complexes of these organic phosphines with organic borons; compounds obtained by adding these organic phosphines to quinone compounds such as maleic anhydride, 1,4-benzoquinone, 2,5-toluquinone, 1,4-naphthoquinone, 2,3-dimethylbenzoquinone, 2,6-dimethylbenzoquinone, 2,3-dimethoxy-5-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, and phenyl-1,4-benzoquinone, and compounds such as diazophenylmethane; and the like.

Among the curing accelerators listed above, organic phosphines and phosphonium salts are preferred, and organic phosphines are most preferred. In addition, the curing accelerator may be used alone or in any combination and ratio of two or more of the above-listed accelerators.

The curing accelerator is preferably used in the range of 0.1 to 20 parts by mass per 100 parts by mass of the total epoxy resin components in the epoxy resin composition. When the content of the curing accelerator is equal to or greater than the lower limit, a good curing acceleration effect can be obtained, while when the content is equal to or less than the upper limit, it is preferable because the desired cured physical properties are easily obtained.

(Inorganic filler)
An inorganic filler can be blended into the epoxy resin composition. Examples of inorganic fillers include fused silica, crystalline silica, glass powder, alumina, calcium carbonate, calcium sulfate, talc, and boron nitride. These may be used alone or in any combination of two or more in any blending ratio. The blending amount of the inorganic filler is preferably 10 to 95 mass% of the total epoxy resin composition.

(Release agent)
A mold release agent can be blended into the epoxy resin composition. Examples of the mold release agent include natural waxes such as carnauba wax, synthetic waxes such as polyethylene wax, higher fatty acids and metal salts thereof such as stearic acid and zinc stearate, and hydrocarbon-based mold release agents such as paraffin. These may be used alone or in any combination of two or more in any blending ratio.

The amount of release agent is preferably 0.001 to 10.0 parts by mass per 100 parts by mass of the total epoxy resin components in the epoxy resin composition. If the amount of release agent is within the above range, it is preferable because good release properties can be achieved while maintaining the curing characteristics.

(Coupling Agent)
A coupling agent can be blended into the epoxy resin composition. The coupling agent is preferably used in combination with an inorganic filler, and blending the coupling agent can improve the adhesion between the epoxy resin matrix and the inorganic filler. Examples of the coupling agent include a silane coupling agent and a titanate coupling agent.

Examples of silane coupling agents include epoxy silanes such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino silanes such as γ-aminopropyltriethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, γ-aminopropyltrimethoxysilane, and γ-ureidopropyltriethoxysilane; mercapto silanes such as 3-mercaptopropyltrimethoxysilane; vinyl silanes such as p-styryltrimethoxysilane, vinyltrichlorosilane, vinyltris(β-methoxyethoxy)silane, vinyltrimethoxysilane, vinyltriethoxysilane, and γ-methacryloxypropyltrimethoxysilane; and polymeric epoxy, amino, and vinyl silanes.

Examples of titanate coupling agents include isopropyl triisostearoyl titanate, isopropyl tri(N-aminoethyl aminoethyl) titanate, diisopropyl bis(dioctyl phosphate) titanate, tetraisopropyl bis(dioctyl phosphite) titanate, tetraoctyl bis(ditridecyl phosphite) titanate, tetra(2,2-diallyloxymethyl-1-butyl)bis(ditridecyl)phosphite titanate, bis(dioctyl pyrophosphate)oxyacetate titanate, and bis(dioctyl pyrophosphate)ethylene titanate.

These coupling agents may be used alone or in any combination and ratio of two or more.

When a coupling agent is used in the epoxy resin composition, the amount of the coupling agent is preferably 0.001 to 10.0 parts by mass per 100 parts by mass of the total epoxy resin components. When the amount of the coupling agent is equal to or greater than the lower limit, the effect of improving the adhesion between the epoxy resin matrix and the inorganic filler by adding the coupling agent tends to be improved. On the other hand, when the amount of the coupling agent is equal to or less than the upper limit, the coupling agent is less likely to bleed out from the resulting cured product, which is preferable.

(Other ingredients)
The epoxy resin composition may contain components other than those described above. Examples of other components include flame retardants, plasticizers, reactive diluents, and pigments, and these may be added as necessary. However, this does not preclude the addition of components other than those listed above.

Examples of flame retardants include halogen-based flame retardants such as brominated epoxy resins and brominated phenol resins; antimony compounds such as antimony trioxide; phosphorus-based flame retardants such as red phosphorus, phosphate esters, and phosphines; nitrogen-based flame retardants such as melamine derivatives; and inorganic flame retardants such as aluminum hydroxide and magnesium hydroxide.

(Curing method)
An epoxy resin cured product can be obtained by curing the epoxy resin composition. Although the curing method is not particularly limited, a cured product can usually be obtained by a thermosetting reaction by heating. During the thermosetting reaction, it is preferable to appropriately select the curing temperature depending on the type of curing agent used. For example, when a phenol-based curing agent is used, the curing temperature is usually 80 to 250°C. In addition, it is also possible to lower the curing temperature by adding a curing accelerator to these curing agents. The reaction time is preferably 0.01 to 20 hours. If the reaction time is equal to or greater than the lower limit, the curing reaction tends to proceed sufficiently, which is preferable. On the other hand, if the reaction time is equal to or less than the upper limit, it is preferable because deterioration due to heating and energy loss during heating are easily reduced.

(Application)
The epoxy resin cured product obtained by curing the epoxy resin composition has a low linear expansion coefficient and excellent heat crack resistance.
Therefore, the epoxy resin cured product can be effectively used in any application where these physical properties are required. For example, it can be suitably used in any of the following applications: coating fields such as electrodeposition coatings for automobiles, heavy-duty anticorrosive coatings for ships and bridges, and coatings for the inner surfaces of beverage cans; electrical and electronic fields such as laminates, semiconductor encapsulants, insulating powder coatings, and coil impregnation; earthquake-resistant reinforcement of bridges, concrete reinforcement, flooring materials for buildings, linings for water facilities, drainage and water-permeable pavements, and adhesives for vehicles and aircraft; and civil engineering, construction, and adhesive fields such as adhesives for vehicles and aircraft.

The epoxy resin composition may be used for the above-mentioned applications after curing, or may be cured during the manufacturing process for the above-mentioned applications.

The present invention will be explained in more detail below with reference to examples and comparative examples. However, the present invention is not limited to the following examples as long as the gist of the invention is not exceeded.

[Raw materials and reagents]
Bisphenol A type epoxy resins (epoxy equivalent weights 950 and 183) and products manufactured by Mitsubishi Chemical Corporation were used.
Rikacid M-700 (acid anhydride), a product of New Japan Chemical Co., Ltd., was used.
Curesol 2E4MZ (curing catalyst) was a product of Shikoku Chemical Industry Co., Ltd.
The phenol novolac resin (PSM-4261) used was a product of Gun-ei Chemical Industry Co., Ltd.
48% by weight sodium hydroxide aqueous solution, sodium bicarbonate, disilediamide (DI
CY) and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) were products of Fujifilm Wako Pure Chemical Industries, Ltd.
Benzyl alcohol used was a product of Sankyo Chemical Co., Ltd.

[analysis]
The production of bisphenol A·2Na was confirmed using a Fourier transform infrared spectrophotometer according to the following procedures and conditions.
Apparatus: Thermo Fisher Scientific FT-IR Nicolet 6700
・Pretreatment: KBr tablet method ・Measurement method: Transmission method ・Light source: Mid-infrared ・Detector: DTGS
Resolution: 4 ^cm
・Number of times accumulated: 32 times

The purity and quantity of bisphenol A.2Na were confirmed and determined by high performance liquid chromatography according to the following procedure and conditions.
Equipment: JASCO RHPLC, JASCO 03150-3M Unifinepak C18 3 μm 150 mm × 3.0 mm ID
Method: Gradient method Analysis temperature: 40°C
Eluent composition:
Liquid A: Acetonitrile Liquid B: Water At analysis time 0 minutes, the ratio of liquid A: liquid B was 30:70 (volume ratio, the same applies below), and from analysis time 0 to 25 minutes the ratio gradually became 100:0.
Flow rate: 0.40 mL/min Detection wavelength: 280 nm

The presence of disodium alkoxide of 2-hydroxy-1,3-bis{4-[2-(4-hydroxyphenyl)propyl]phenoxypropane represented by the following formula (3) (hereinafter, sometimes referred to as "compound (3)") in the bisphenol compositions obtained in the Examples and Comparative Examples was confirmed by the following procedures and conditions.
Separation equipment: AQUITY UPLC H-CLASS manufactured by Waters Corporation, Unifinepak manufactured by JASCO
C18 3μm 150mm x 3.0mm ID.
Method: Gradient method Analysis temperature: 40°C
Eluent composition:
Liquid A: distilled water Liquid B: acetonitrile At analysis time 0 minutes, the ratio of liquid A: liquid B was 90:10 (volume ratio, the same applies below), and from analysis time 0 to 15 minutes, the ratio gradually became 100:0.
Flow rate: 0.50 mL/min Detector: Xevo TQD tandem quadrupole mass spectrometer

[Dissolved color of bisphenol composition]
The dissolution color of the bisphenol composition was measured by mixing the bisphenol composition with distilled water to prepare a 3% by mass solution of the dissolution color, and measuring the Yellow Index (YI) thereof using a ZE6000 made by Nippon Denshoku Industries Co., Ltd.

[Epoxy resin melt color]
The dissolved color of the epoxy resin was measured by mixing the epoxy resin with acetone to prepare a 3% by mass dissolved color solution, and measuring the Hazen color number (APHA) using a Nippon Denshoku Industries Co., Ltd. "ZE6000."

Example 1
500 g of bisphenol A type epoxy resin (epoxy equivalent: 950) and 10 g of 5% by mass aqueous sodium hydrogen carbonate solution were placed in an aluminum cup and thoroughly mixed to obtain mixture A. The obtained mixture A was cured at 200° C. for 100 hours to obtain a single resin cured product.

630 g of benzyl alcohol and 50 g of 48% by weight aqueous sodium hydroxide solution were placed in a separable flask equipped with a stirring blade, a cooling tube, and a thermometer under a nitrogen atmosphere. After creating a full vacuum inside the separable flask, the internal temperature was gradually increased and some of the water and benzyl alcohol were extracted, completely distilling off the water in the separable flask. The pressure inside the separable flask was restored with nitrogen, yielding 640 g of treated liquid.

60 g of the cured single resin was added to 640 g of the resulting treatment liquid, and the temperature was then raised to 200°C at normal pressure over 1 hour. The liquid inside the separable flask was kept at 200°C for 3 hours, causing the cured single resin to completely dissolve, and 700 g of decomposition liquid a was obtained. When the composition of a portion of the resulting decomposition liquid a was confirmed by high-performance liquid chromatography, it was found to contain 4.3 mass% (4.3 mass% x 700 g = 30.1 g) of bisphenol A.2Na.

700 g of water was added to 700 g of decomposition liquid a, and oil-water separation was performed at room temperature to obtain 650 g of aqueous phase a. Water was distilled off from aqueous phase a under reduced pressure to concentrate it 5 times, and the concentrated liquid was added dropwise to 2800 g of acetone to obtain suspension a. Suspension a was filtered, and the residue was air-dried to obtain 42 g of powdered bisphenol composition A.

A portion of the resulting bisphenol composition A was examined using a Fourier transform infrared spectrophotometer, and it was found to contain bisphenol A·2Na.
In addition, a part of the obtained bisphenol composition A was analyzed by high performance liquid chromatography to confirm the composition, and it was found that the content of bisphenol A.2Na was 45% by mass (45% by mass×42 g=18.9 g), and the ratio of the content of compound (3) to the content of bisphenol A.2Na was 3.5% by mass (3.5% by mass×18.9 g=0.7 g). In addition, the Yellow Index of a 3% by mass aqueous solution was 18.4.

Example 2
The same procedure as in Example 1 was carried out except that the temperature was maintained at 200° C. for 5 hours after mixing the thermosetting resin and the treatment liquid, to obtain a decomposition liquid b.
Thereafter, the same procedure as in Example 1 was carried out to obtain a powdered bisphenol composition B. A part of the obtained bisphenol composition B was subjected to high performance liquid chromatography to confirm the composition, and it was found that the content of bisphenol A.2Na was 39 mass%, and the ratio of the content of compound (3) to the content of bisphenol A.2Na was 0.5 mass%. In addition, the Yellow Index of a 3 mass% aqueous solution was 19.7.

Example 3
The same procedure as in Example 1 was carried out except that the temperature was maintained at 190° C. for 3 hours after mixing the thermosetting resin and the treatment liquid, to obtain decomposition liquid c.
Thereafter, a powdered bisphenol composition C was obtained in the same manner as in Example 1. A part of the obtained bisphenol composition C was subjected to high performance liquid chromatography to confirm the composition, and it was found that the content of bisphenol A.2Na was 42 mass%, and the ratio of the content of compound (3) to the content of bisphenol A.2Na was 12.9 mass%. In addition, the yellow index of a 3 mass% aqueous solution was 19.8.

Comparative Example 1
The same procedure as in Example 1 was carried out except that the temperature was maintained at 200° C. for 1.5 hours after mixing the thermosetting resin and the treatment liquid, to obtain a decomposition liquid d.
Thereafter, the same procedure as in Example 1 was carried out to obtain a powdered bisphenol composition D. When the composition of a part of the obtained bisphenol composition D was confirmed by high performance liquid chromatography, the content of bisphenol A.2Na was 45 mass%, and the ratio of the content of compound (3) to the content of bisphenol A.2Na was 37.4 mass%.
The yellow index of the aqueous solution was 22.0.

The ratio of the content of compound (3) to the content of bisphenol A.2Na in the bisphenol compositions obtained in Examples 1 to 3 and Comparative Example 1, and the dissolution color of the bisphenol compositions are summarized in Table 1. From Table 1, it can be seen that bisphenol compositions in which the ratio of the content of compound (3) to the content of bisphenol A.2Na is 15 mass% or less have little coloring and good dissolution color.

Example 4
280 g of bisphenol A type epoxy resin (epoxy equivalent: 183), 2 g of DICY, and 3 g of DCMU were placed in an aluminum cup and mixed thoroughly to obtain a mixture f. The obtained mixture f was heated at 150° C. for 3 hours to obtain an amine cured product.

Bisphenol composition E was obtained in the same manner as in Example 1, except that 60 g of the amine cured product was used as the thermosetting resin. When the composition of a portion of the obtained bisphenol composition E was confirmed by high performance liquid chromatography, the content of bisphenol A.2Na was 41 mass%, and the ratio of the content of compound (3) to the content of bisphenol A.2Na was 5.6 mass%. In addition, the Yellow Index of a 3 mass% aqueous solution was 13.5.

The types of cured resins in Examples 1 and 4, the ratio of the content of compound (3) to the content of bisphenol A·2Na, and the dissolution color of the bisphenol compositions are summarized in Table 2. From Table 2, it can be seen that bisphenol compositions with little coloring can be obtained regardless of the type of cured resin.

Example 5
In a 1 L four-neck flask equipped with a thermometer, a stirrer, and a cooling tube, 44 g of bisphenol composition A, 259 g of epichlorohydrin, 100 g of isopropanol, and 36 g of water were charged, and the mixture was heated to 40° C. to dissolve uniformly. Then, 3 g of a 48.5% by mass aqueous solution of sodium hydroxide was added.
8g was added dropwise over 90 minutes. At the same time as the dropwise addition, the temperature was raised from 40°C to 65°C over 90 minutes. After that, the mixture was held at 65°C for 30 minutes to complete the reaction, and the reaction liquid was transferred to a 1L separatory funnel, and 69g of water at 65°C was added and left to stand at 65°C for 1 hour. After standing, the aqueous phase was extracted from the separated oil phase and aqueous phase, and by-product salts and excess sodium hydroxide were removed. Then, epichlorohydrin was completely removed under reduced pressure at 150°C, 102g of methyl isobutyl ketone was charged, and the mixture was heated to 65°C and uniformly dissolved, and then 1.4g of a 48.5% by mass aqueous sodium hydroxide solution was charged and reacted for 60 minutes. After the reaction, 57g of methyl isobutyl ketone was charged into the reaction mixture, and the mixture was washed with 200g of water four times. Then, methyl isobutyl ketone was completely removed under reduced pressure at 150°C to obtain epoxy resin A. The epoxy equivalent of the obtained epoxy resin A was measured in accordance with JIS K 7236 (2009) and found to be 230 g/equivalent. The Hazen color number of a 3 mass% acetone solution of the obtained epoxy resin A was 41.

<Comparative Example 2>
The same procedure as in Example 5 was carried out to obtain epoxy resin D from bisphenol composition D.
The epoxy equivalent of the obtained epoxy resin D was measured according to IEC 61114-1 (2009) and was found to be 235 g/equivalent. The Hazen color number of a 3% by mass acetone solution of the obtained epoxy resin D was 127.

The dissolved colors of the bisphenol compositions and the epoxy resins in Example 5 and Comparative Example 2 are summarized in Table 3. From Table 3, it can be seen that by using a bisphenol composition with little coloring, an epoxy resin with little coloring can be obtained.

Claims (12)

The metal alkoxide is a bisphenol metal alkoxide represented by general formula (1),
A solid bisphenol composition, wherein the ratio of the content of the bisphenol glycerin ether metal alkoxide to the content of the bisphenol metal alkoxide is 15 mass % or less.

(In general formula (1), each R is independently a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms; each X is independently a direct bond, a hydrocarbon group having 1 to 14 carbon atoms, a halogenated hydrocarbon group having 1 to 14 carbon atoms, -SO ₂ -, -S-, -CO-, or -O-; each M is independently an alkali metal, an alkaline earth metal, magnesium, or aluminum; and n is the valence of M.) The bisphenol composition according to claim 1, wherein the ratio of the content of the bisphenol glycerin ether metal alkoxide to the content of the bisphenol metal alkoxide is 0.1 mass ppm or more. The bisphenol composition according to claim 1, wherein the bisphenol metal alkoxide is a compound represented by general formula (2):

(In general formula (2), R, X, M, and n are the same as R, X, M, and n in general formula (1), respectively.) The bisphenol composition according to claim 1, wherein in the general formula (1), R is a hydrogen atom and X is a dimethylmethylene group. The bisphenol composition according to claim 1, wherein in the general formula (1), M is an alkali metal. The bisphenol composition according to claim 1, wherein in the general formula (1), M is an alkaline earth metal. A method for producing the bisphenol composition according to any one of claims 1 to 6, comprising the following steps A to C:
Step A: A step of decomposing a cured thermosetting resin material to obtain a decomposition liquid A containing the bisphenol metal alkoxide and the bisphenol glycerin ether metal alkoxide. Step B: A step of adding water to the decomposition liquid A obtained in step A to obtain an oil-water two-phase liquid B. Step C: A step of subjecting the oil-water two-phase liquid B obtained in step B to oil-water separation, mixing the obtained aqueous phase C with an organic solvent, and obtaining a suspension D. Step D: A step of subjecting the suspension D obtained in step C to solid-liquid separation, and recovering the solid phase. The method for producing a bisphenol composition according to claim 7, wherein the step B is a step of obtaining a decomposition liquid A' by subjecting the decomposition liquid A obtained in the step A to solid-liquid separation to remove insoluble matters, and obtaining an oil-water two-phase liquid B by adding water to the decomposition liquid A'. A method for producing an epoxy resin, comprising the steps of contacting the bisphenol composition according to any one of claims 1 to 6 with epihalohydrin, and reacting the bisphenol metal alkoxide in the bisphenol composition, the bisphenol glycerin ether metal alkoxide, and the epihalohydrin. A method for producing an epoxy resin, comprising a step of reacting the epoxy resin obtained by the method according to claim 9 with a polyhydric hydroxy compound. A method for producing a cured epoxy resin product, comprising a step of curing an epoxy resin composition containing an epoxy resin and a curing agent obtained by the method according to claim 9. A method for producing a cured epoxy resin product, comprising a step of curing an epoxy resin composition containing an epoxy resin obtained by the method of claim 10 and a curing agent.