WO2023182522A1

WO2023182522A1 - Epoxy resin, cured body of same and method for producing epoxy resin

Info

Publication number: WO2023182522A1
Application number: PCT/JP2023/012033
Authority: WO
Inventors: 世吾小野; 勇司江口
Original assignee: 積水化学工業株式会社
Priority date: 2022-03-24
Filing date: 2023-03-24
Publication date: 2023-09-28
Also published as: JPWO2023182522A1; JP7537028B2

Abstract

The present invention provides an epoxy resin which has a skeleton represented by formula (1). In formula (1), each of R⁴ and R⁵ independently represents a hydrogen atom, an alkoxy group or -OG; * may be a binding site to be bonded with another structure; n represents an integer of 0 to 100; and G represents a glycidyl group.

Description

Epoxy resin, its cured product, and method for producing epoxy resin

The present invention relates to an epoxy resin having a truxylate structure and a cured product thereof.

Since petroleum is a limited resource and causes global environmental problems such as carbon dioxide emissions, there has been a demand in recent years for the use of alternative resources. The use of biomass is attracting attention as an alternative resource to oil. Polylactic acid and polyhydroxybutyric acid have been commercialized as resins made from biomass, and production volumes are increasing in response to expanding demand, particularly in the EU.

As for biomass, edible biomass is mainly used from the viewpoint of ease of handling, but as edible biomass competes with use as food, there is a growing demand for the use of non-edible biomass. , various studies have been conducted. For example, in Non-Patent Document 1, a bifunctional epoxy resin obtained using ferulic acid, which can be obtained by depolymerizing lignin, has a higher glass transition temperature and excellent tensile strength than conventional bisphenol A epoxy resins. It has been disclosed that it exhibits strength, and it has also been shown that performance is improved by compounding glycidyl ether of furfuryl alcohol.

In addition, in recent years, consideration has been given to producing valuable materials using microorganisms. For example, using microorganisms to produce compounds with a hydroxycinnamic acid structure such as p-coumaric acid from biomass-derived compounds such as L-tyrosine. known to be synthesized. Generally, microbial reactions are highly efficient and can be carried out in a mild environment.

Compounds that can be synthesized by microorganisms are also being considered for use in resin production. For example, in Patent Document 1, an epoxy resin is synthesized by reacting epichlorohydrin with p-hydroxycinnamic acid, and the obtained epoxy resin is cured with a curing agent together with glycidyl furfuryl ether, thereby achieving a high glass transition temperature and It is disclosed that it has excellent mechanical strength.

China Publication No. 112409298

However, since components derived from non-edible biomass such as lignin have low degradability, it is difficult to efficiently obtain raw material compounds, and the process for synthesizing epoxy resins tends to be complicated. Furthermore, there is a problem that compounds obtained from biomass generally have inferior performance compared to polymers derived from petrochemicals.

Therefore, an object of the present invention is to provide an epoxy resin that is a compound that can be obtained from biomass, can be easily produced, and has good thermal performance.

The present inventors have discovered that an epoxy resin obtained from dihydroxytruxylic acid, which is a dimer of paracoumaric acid that can be easily produced by microorganisms, can solve the above problems, and have completed the present invention. The present invention provides the following [1] to [13].
[1] An epoxy resin having a skeleton represented by the following formula (1).

In addition, in formula (1), R ⁴ and R ⁵ are each independently a hydrogen atom, an alkoxy group, or -OG. * may be a binding site with another structure. G represents a glycidyl group.
[2] The epoxy resin according to [1] above, which has a structure represented by the following formula (1-1).

In addition, in formula (1-1), R ¹ and R ³ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, which may have a heteroatom, or a glycidyl group, and R ² is It is a divalent hydrocarbon group having 2 to 20 carbon atoms that may have a heteroatom. In each benzene ring, one of R ⁴ and R ⁵ is a hydrogen atom, and the other is a hydrogen atom, -OCH ₃ or -OG. n is an integer from 0 to 100.
[3] The epoxy resin according to [1] above, which has a structure represented by the following formula (1-2).

In addition, in formula (1-2), R ¹ and R ³ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, which may have a hetero atom, or a glycidyl group, and R ² is It is a divalent hydrocarbon group having 2 to 20 carbon atoms that may have a heteroatom. n is an integer from 0 to 100.
[4] The epoxy resin according to [2] or [3] above, wherein R ¹ and R ³ are glycidyl groups, and n is 0.
[5] The epoxy resin according to [2] or [3] above, wherein R ¹ and R ³ are alkyl groups having 1 to 6 carbon atoms, and n is 0.
[6] The epoxy resin according to the above [2] or [3], wherein R ¹ and R ³ are methyl groups.
[7] The epoxy resin according to the above [1], which has a structure represented by the following formula (1-3).

In each benzene ring of formula (1-3), one of R ⁴ and R ⁵ is a hydrogen atom, and the other is a hydrogen atom, -OCH ₃ or -OG. Further, R ⁶ is a hydrogen atom, -COOG, or -COOR ¹ , and R ⁷ is a hydrogen atom, -COOG, or -COOR ³ . R ¹ and R ³ are alkyl groups.
[8] The epoxy resin according to any one of [1] to [7] above, wherein the skeleton represented by formula (1) is derived from biomass.
[9] A cured product obtained by curing the epoxy resin according to any one of [1] to [8] above.
[10] A method for producing an epoxy resin, which comprises reacting a compound having a skeleton represented by the following formula (2) with epihalohydrin to obtain an epoxy resin.

In addition, in formula (2), R ¹⁴ and R ¹⁵ are each independently a hydrogen atom, an alkoxy group, or -OH. * may be a binding site with another structure.
[11] The method for producing an epoxy resin according to [10] above, wherein an epoxy resin is obtained by reacting a compound represented by the following formula (2-1) with epihalohydrin.

In the above formula (2-1), R ¹¹ and R ¹³ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms which may have a hetero atom. R ¹² is a divalent hydrocarbon group having 2 to 20 carbon atoms which may have a heteroatom. In each benzene ring, one of R ¹⁴ and R ¹⁵ is a hydrogen atom, and the other is a hydrogen atom, -OCH ₃ or -OH. m is an integer from 0 to 100.
[12] The method for producing an epoxy resin according to the above [10], wherein an epoxy resin is obtained by reacting a compound represented by the following formula (2-2) with epihalohydrin.

In the above formula (2-2), R ¹¹ and R ¹³ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms which may have a hetero atom. R ¹² is a divalent hydrocarbon group having 2 to 20 carbon atoms which may have a heteroatom. m is an integer from 0 to 100.
[13] The method for producing an epoxy resin according to the above [10], wherein an epoxy resin is obtained by reacting a compound represented by the following formula (2-3) with epihalohydrin.

In each benzene ring of formula (2-3), one of R ¹⁴ and R ¹⁵ is a hydrogen atom, and the other is a hydrogen atom, -OCH ₃ or -OH. R ¹⁶ is a hydrogen atom or -COOR ¹¹ , and R ¹⁷ is a hydrogen atom or -COOR ¹³ . R ¹¹ and R ¹³ are each independently a hydrogen atom or an alkyl group.

The present invention can provide an epoxy resin that is a compound that can be obtained from biomass, is easily produced, and has good thermal performance.

1 shows a ¹ H-NMR spectrum of dimethyl 4,4'-dihydroxytruxylate synthesized in Example 1. 1 shows a ¹ H-NMR spectrum of the epoxy resin synthesized in Example 1.

<Epoxy resin>
Hereinafter, the present invention will be described in more detail using embodiments.
The epoxy resin of the present invention has a skeleton represented by the following formula (1). Although the epoxy resin having the skeleton of the following formula (1) is a compound that can be obtained from biomass, it can be easily produced and has good thermal performance.

In formula (1), R ⁴ and R ⁵ are each independently a hydrogen atom, an alkoxy group, or -OG. * may be a binding site with another structure. G represents a glycidyl group.

In the above formula (1), the alkoxy groups of R ⁴ and R ⁵ may be, for example, alkoxy groups having 1 to 4 carbon atoms, such as methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group. , sec-butoxy group, tert-butoxy group, etc. Among these, methoxy group (-OCH ₃ ) is preferred.
In formula (1), R ⁴ and R ⁵ in each benzene ring may be the same or different, but in each benzene ring, either one of R ⁴ and R ⁵ independently It is preferable that one is a hydrogen atom and the other is a hydrogen atom, an alkoxy group, or -OG. Note that the other of R ⁴ and R ⁵ in one molecule is preferably the same group.
When either one of R ⁴ and R ⁵ is a hydrogen atom, it can be easily produced using coumaric acid or a compound obtained from coumaric acid by reaction using an enzyme, as described below.

When * becomes a bonding site, it may be bonded to another skeleton shown in formula (1) via a linking group (for example, -COO-R ² -COO-, which will be described later), or it may be bonded to another functional group. (For example, functional groups represented by -COOR ¹ and -COOR ³ , which will be described later). Furthermore, if it does not serve as a bonding site, it may serve as a site that bonds to two hydrogen atoms.

The epoxy resin of the present invention is preferably a compound having a structure represented by the following formula (1-1).

In formula (1-1), R ¹ and R ³ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, which may have a hetero atom, or a glycidyl group, and R ² is a hetero atom. It is a divalent hydrocarbon group having 2 to 20 carbon atoms which may have . n is an integer from 0 to 100. G represents a glycidyl group.
Moreover, R ⁴ and R ⁵ are the same as above. Therefore, it is preferable that in each benzene ring, one of R ⁴ and R ⁵ is a hydrogen atom, and the other is one of a hydrogen atom, -OCH ₃ and -OG. In addition, it is preferable that the other of R ⁴ and R ⁵ in one molecule is the same group.

Furthermore, in formulas (1) and (1-1), both R ⁴ and R ⁵ are preferably hydrogen atoms from the viewpoint of easy synthesis from biomass. Therefore, the epoxy resin of the present invention preferably has a structure represented by the following formula (1-2).

In addition, in formula (1-2), R ¹ and R ³ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, which may have a hetero atom, or a glycidyl group, and R ² is It is a divalent hydrocarbon group having 2 to 20 carbon atoms that may have a heteroatom. n is an integer from 0 to 100. G represents a glycidyl group.

In each of the above formulas (1-1) and (1-2), the monovalent hydrocarbon group having 1 to 20 carbon atoms in R ¹ and R ³ may be an aliphatic hydrocarbon group or an aromatic ring. It may be an aromatic hydrocarbon group having These may or may not have heteroatoms. Further, examples of the heteroatom include a nitrogen atom, a sulfur atom, an oxygen atom, a halogen atom, and a phosphorus atom. Heteroatoms include, but are not particularly limited to, oxygen atoms forming ether bonds, ester bonds, keto groups, alkoxy groups, etc., sulfur atoms forming sulfonyl groups, thiol bonds, etc., and hydrogen atoms substituted for hydrocarbon groups. Examples include halogen atoms.
The monovalent hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and still more preferably 1 to 3 carbon atoms.

The aliphatic hydrocarbon group in R ¹ and R ³ may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group, and examples thereof include an alkyl group and an alkenyl group. The monovalent hydrocarbon group in R ¹ and R ³ is preferably an alkyl group because it is easy to manufacture and tends to improve thermal stability. The alkyl group may be linear, have a branched structure, or have a cyclic structure. Specific alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, various pentyl groups, various hexyl groups, and various heptyl groups. group, and various octyl groups. In addition, "various" means various isomers including sec-, tert-, iso-, etc. in addition to linear (n-), and the same applies below. Further, the alkyl group may have a cyclic structure such as a cyclohexyl group.
The alkyl groups in R ¹ and R ³ each independently preferably have 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, even more preferably 1 to 3 carbon atoms, and most preferably both are methyl groups. preferable.

In each of formulas (1-1) and (1-2), n is 0 to 100 as described above, preferably 0 to 50, more preferably 0 to 10, still more preferably 0 to 5, particularly preferably It is 0. By reducing the number of n, it is possible to prevent the epoxy resin from increasing in molecular weight, suppressing variations in quality, and improving handleability.

The divalent hydrocarbon group having 2 to 20 carbon atoms in R ² may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group having an aromatic ring. These may or may not have a heteroatom. Details of the heteroatom are as described for R ¹ and R ³ .
The aliphatic hydrocarbon group in R ² may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group, but a saturated hydrocarbon group is preferable. The saturated hydrocarbon group in R ² may be linear, have a branched structure, or have a cyclic structure. As mentioned above, the saturated hydrocarbon group may or may not have a heteroatom, but it is preferable that it does not have a heteroatom. The number of carbon atoms in the divalent hydrocarbon group in R ² is preferably 2 to 10, more preferably 2 to 6, and still more preferably 2 to 4.

In addition to the above, the aliphatic hydrocarbon group which may have a heteroatom in R ² is also preferably a hydroxypropylene group. A hydroxypropylene group is a functional group obtained by removing two hydrogen atoms bonded to a carbon atom from hydroxypropane, and is also called a hydroxypropanediyl group. The hydroxypropylene group is a structural unit derived from epihalohydrin, which will be described later.
In the hydroxypropylene group, the position of the hydrogen atom to be removed and the position of the hydroxyl group are arbitrary, but typically it is a 2-hydroxypropane-1,3-diyl group (-CH ₂ CHOHCH ₂ -). The compounds represented by formulas (1-1) and (1-2) each have a 2-hydroxypropane-1,3-diyl group in which R ² is a 2-hydroxypropane-1,3-diyl group. In particular, it can be easily synthesized from compounds shown in formulas (2-4) to (2-6).
In addition, when there is a plurality of R ² in one molecule, the plurality of R ² in one molecule may be the same or different. Among the above, R ² is preferably a hydroxypropylene group.

In the present invention, in the structures represented by formulas (1-1) and (1-2), both R ¹ and R ³ are preferably glycidyl groups. Epoxy resins in which both R ¹ and R ³ are glycidyl groups make it easier to obtain an epoxy cured product with a high crosslinking density. Even when both R ¹ and R ³ are glycidyl groups, R ² and n are as described above in the epoxy resin having the structures shown in formulas (1-1) and (1-2), respectively. Therefore, in the epoxy resin in which both R ¹ and R ³ are glycidyl groups, it is particularly preferable that n is 0.

In the present invention, it is also preferable that in the compounds having formulas (1-1) and (1-2), both R ¹ and R ³ are monovalent hydrocarbon groups which may have a heteroatom. . In the epoxy resin having the structures shown in formulas (1-1) and (1-2) according to this embodiment, R ² and n are as described above, and even if R ¹ and R ³ have a heteroatom, Preferred embodiments of the monovalent hydrocarbon group are also as described above. Therefore, in this embodiment, R ¹ and R ³ are both preferably alkyl groups, and the alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 3 carbon atoms. most preferably both R ¹ and R ³ are methyl groups. Also in this embodiment, n is particularly preferably 0 as described above. The epoxy resin in this embodiment makes it easier to obtain a cured epoxy product with relatively excellent flexibility.

In the epoxy resin of the present invention, n is preferably 0 as described above, and therefore, it is also preferably a compound having the structure shown in the following formula (1-3).

In formula (1-3), R ⁶ is a hydrogen atom or -COOR ¹ , and R ⁷ is a hydrogen atom or -COOR ³ . R ¹ , R ³ , R ⁴ and R ⁵ are as described above.

Details of preferred embodiments of R ⁴ and R ⁵ are as described above. Therefore, in formula (1-3), in each benzene ring, one of R ⁴ and R ⁵ is a hydrogen atom, and the other is one of a hydrogen atom, -OCH ₃ , and -OG. is preferable, and in this case, it is more preferable that the other of R ⁴ and R ⁵ in one molecule is the same functional group. More preferably, both R ⁴ and R ⁵ are hydrogen atoms.
Further, preferred embodiments of R ¹ and R ³ are also as described above. Therefore, also in formula (1-3), R ⁶ is a hydrogen atom, -COOG, or -COOR ¹ , R ⁷ is a hydrogen atom, -COOG, or -COOR ³ , and R ¹ and R ³ are preferably alkyl groups. Among these, it is more preferable that R ⁶ and R ⁷ are both a hydrogen atom, -COOG, or -COOR.

As the epoxy resin having the structure of the above formula (1-3), compounds having the structures represented by the following formulas (1-4) to (1-10) are preferable, and among them, compounds having the structure represented by the formula (1-4) are preferred. More preferred are compounds exhibiting the following structure. Compounds having structures represented by the following formulas (1-4) to (1-10) are coumaric acid, ferulic acid obtained by enzymatic conversion of coumaric acid, caffeic acid, or caffeic acid obtained by enzymatic conversion of coumaric acid. , and can be easily synthesized from 4-vinylphenol obtained by decarbonizing reaction, so it can be easily produced from biomass raw materials.

(In formulas (1-8), (1-9), and (1-10), R is an alkyl group. Details of the alkyl group are as above.)

<Production method of epoxy resin>
The epoxy resin of the present invention can be synthesized by reacting a compound having a skeleton represented by the following formula (2) (hereinafter also referred to as a raw material compound) with epihalohydrin.

In addition, in formula (2), R ¹⁴ and R ¹⁵ are each independently a hydrogen atom, an alkoxy group, or -OH. * may be a binding site with another structure.
In the above formula (2), the alkoxy groups of R ¹⁴ and R ¹⁵ are the same as the alkoxy groups of R ⁴ and R ⁵ described above, and are preferably methoxy groups.
In formula (2), R ¹⁴ and R ¹⁵ in each benzene ring may be the same or different, but in each benzene ring, either one of R ¹⁴ and R ¹⁵ is independently selected. is a hydrogen atom, and the other is preferably a hydrogen atom, an alkoxy group such as a methoxy group, or -OH. Note that the other of R ¹⁴ and R ¹⁵ in one molecule is preferably the same group.

In the above formula (2-1), R ¹¹ and R ¹³ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms which may have a hetero atom. R ¹² is a divalent hydrocarbon group having 2 to 20 carbon atoms which may have a heteroatom. The details of the monovalent hydrocarbon group having 1 to 20 carbon atoms which may have a hetero atom and the divalent hydrocarbon group having 2 to 20 carbon atoms which may have a hetero atom are as described above. be. However, the divalent hydrocarbon group having 2 to 20 carbon atoms which may have a heteroatom is usually a structural unit derived from a dihydroxy compound described below, and therefore is usually other than a hydroxypropylene group, for example, A saturated hydrocarbon group having no heteroatom or a saturated hydrocarbon group having an ether bond as a heteroatom is preferred.
R ¹⁴ and R ¹⁵ are as described above.
In formula (2-1), m is an integer of 0 to 100, preferably 0 to 50, more preferably 0 to 10, still more preferably 0 to 5, particularly preferably 0.

Furthermore, in formulas (2) and (2-1), both R ¹⁴ and R ¹⁵ are preferably hydrogen atoms. Therefore, the raw material compound preferably has a structure represented by the following formula (2-2).

In the compound represented by formula (2-2), R ¹¹ , R ¹² , R ¹³ and m are as described above.

Further, in the raw material compound of the present invention, m is preferably 0 as described above, and therefore, it is also preferably a compound having the structure shown in the following formula (2-3).

In formula (2-3), R ¹⁶ is a hydrogen atom or -COOR ¹¹ , and R ¹⁷ is a hydrogen atom or -COOR ¹³ . R ¹¹ , R ¹³ , R ¹⁴ and R ¹⁵ are as described above.

Preferred embodiments of R ¹⁴ and R ¹⁵ are as described above. Therefore, in formula (2-3), in each benzene ring, one of R ¹⁴ and R ¹⁵ is a hydrogen atom, and the other is one of a hydrogen atom, -OCH ₃ , and -OH. is preferable, and in this case, it is more preferable that the other of R ¹⁴ and R ¹⁵ is the same functional group. More preferably, both R ¹⁴ and R ¹⁵ are hydrogen atoms.
Further, preferred embodiments of R ¹¹ and R ¹³ are also as described above. Also in formula (2-3), R ¹⁶ is a hydrogen atom or -COOR ¹¹ , and R ¹⁷ is a hydrogen atom or -COOR ¹³ . R ¹¹ and R ¹³ are each independently a hydrogen atom or an alkyl group. Among these, it is more preferable that R ¹⁶ and R ¹⁷ are both a hydrogen atom, -COOH, or -COOR (R is an alkyl group).

More specifically, the raw material compound is preferably dihydroxytruxylic acid represented by the following formula (2-4) or an ester compound thereof.

Dihydroxytruxylic acid represented by the above formula (2-4) is a paracoumaric acid dimer, and can be obtained by dimerizing paracoumaric acid. The method of dimerizing paracoumaric acid is not particularly limited, but examples include a method of dimerizing paracoumaric acid by light irradiation such as ultraviolet irradiation. Paracoumaric acid is dimerized by the double bond at the beta position of paracoumaric acid being cleaved by UV irradiation and the molecules recombining with each other, and paracoumaric acid dimer having the structure shown in the above formula (2-4). You can get a body.

Further, the raw material compound may be a compound represented by any of the following formulas (2-5) to (2-7), or an ester compound of a compound represented by (2-5) or (2-6). . The compounds of formulas (2-5) to (2-7) below can be obtained by dimerizing ferulic acid, caffeic acid, and 4-vinylphenol, respectively. The method of dimerization is not particularly limited, but may include a method of dimerization by light irradiation such as ultraviolet irradiation, similar to paracoumaric acid. Ferulic acid, caffeic acid, and 4-vinylphenol are obtained by enzymatic conversion reaction of coumaric acid, or by enzymatic conversion of coumaric acid and decarbonization reaction, so the formula (2-4) Similar to dihydroxytruxylic acid shown in , it can be easily produced from biomass raw materials.

The ester compound of dihydroxytruxylic acid shown in the above formula (2-4) is preferably a compound having the structure shown in the following formula (2-8), which is obtained by esterifying the above dihydroxytruxylic acid with a monohydroxy compound. can be mentioned.

In the above formula (2-8), R ¹⁸ and R ¹⁹ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms which may have a hetero atom. Details of the monovalent hydrocarbon group having 1 to 20 carbon atoms which may have a heteroatom are as described above. Therefore, R ¹⁸ and R ¹⁹ are each independently preferably an alkyl group, more preferably an alkyl group having 1 to 10 carbon atoms, even more preferably an alkyl group having 1 to 6 carbon atoms, even more preferably a carbon alkyl group. It is an alkyl group of number 1 to 3, and R ¹⁸ and R ¹⁹ are most preferably both methyl groups.

Further, as the ester compound of the compound represented by the above formula (2-5) or formula (2-6), preferably a compound having the structure represented by formula (2-9) or a structure represented by formula (2-10) is used. Examples include compounds having the following.

In the above formulas (2-9) and (2-10), R ¹⁸ and R ¹⁹ are as described in the above formula (2-8).

Further, the paracoumaric acid ester compound represented by formula (2-4) may be a compound obtained by esterifying the above-mentioned dihydroxytruxylic acid with a dihydroxy compound, or a dihydroxy compound and a monohydroxy compound. The compound esterified with at least a dihydroxy compound in this way is a compound in which m is 1 or more in formula (2-1) or formula (2-2).
In the case of esterification with a dihydroxy compound and a monohydroxy compound, dihydroxytruxylic acid may be esterified with a dihydroxy compound and then further esterified with a monohydroxy compound, or after esterification with a monohydroxy compound, it may be esterified with a dihydroxy compound. or esterification with a dihydroxy compound and esterification with a monohydroxy compound may be performed in parallel.
When esterifying with a dihydroxy compound and a monohydroxy compound, m is 1 or more in formula (2-1) or (2-2), and at least one of R ¹¹ and R ¹³ may have a hetero atom. Although it is a monovalent hydrocarbon group, it is preferable that both R ¹¹ and R ¹³ are monovalent hydrocarbon groups that may have a heteroatom.

The method of esterifying dihydroxytruxylic acid with a hydroxy compound (monohydroxy compound, dihydroxy compound, or both) is not particularly limited, but includes a method of condensing a carboxylic acid and a hydroxy compound with an acid catalyst, a method of esterifying dihydroxytruxylic acid with a hydroxy compound, Examples include, but are not limited to, a method in which an acid halide such as an acid chloride is reacted with a hydroxy compound.

The monohydroxy compound used in the above esterification may be an aromatic monohydroxy compound or an aliphatic monohydroxy compound, but an aliphatic monohydroxy compound is preferable, and an alkyl monoalcohol is more preferable among them. The alkyl monoalcohol may be a straight-chain alcohol, but may also have a branched structure or a cyclic structure.
Specifically, the alkyl monoalcohols include methanol, ethanol, isopropanol, n-propanol, n-butanol, isobutanol, sec-butanol, tert-butanol, various pentanols, various hexanols, various heptanols, various octanols, Examples include various nonanol, various decanol, cyclopentanol, cyclohexanol, methylcyclohexanol, cyclohexane methanol, and among these, metal is particularly preferred.

Further, the dihydroxy compound used for esterification may be an aromatic dihydroxy compound or an aliphatic dihydroxy compound, but aliphatic dihydroxy compounds are preferable, and among them, alkyl diols are more preferable. The aliphatic dihydroxy compound may be a straight-chain alcohol, but may also have a branched structure or a cyclic structure.
Specific examples of aliphatic dihydroxy compounds include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 3-methyl. -1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, neopentyl glycol, 1,4 -cyclohexanediol, 1,4-cyclohexanedimethanol and the like. Among these, ethylene glycol is preferred.

Furthermore, as the ester compound of the compound represented by formula (2-5) or formula (2-6), the compound represented by formula (2-5) or formula (2-6) above can be used as a dihydroxy compound, or a dihydroxy compound and It may also be a compound esterified with a monohydroxy compound. The compound esterified with at least a dihydroxy compound in this way is a compound in which m is 1 or more in formula (2-1) or formula (2-2).
Details of the compound obtained by esterifying the compound represented by formula (2-5) or formula (2-6) with a dihydroxy compound, or a dihydroxy compound and a monohydroxy compound are the same as those for the compound represented by formula (2-4). Therefore, the explanation will be omitted.

Epihalohydrins that can be used in the synthesis of epoxy resins include epifluorohydrin, epichlorohydrin, epibromohydrin, and epiiodohydrin, and among these, epichlorohydrin is preferred in terms of reactivity and economy.

As mentioned above, the epoxy resin of the present invention can be obtained by reacting a compound having the skeleton shown in formula (2) with epihalohydrin. For the epoxy resin, a compound having the skeleton shown in formula (2) and epihalohydrin are preferably mixed and reacted, for example, in a reactor.
In this production method, the amount of epihalohydrin added to the compound having the skeleton shown in formula (2) in the reaction system is preferably 1 equivalent or more. By adding 1 equivalent or more of epihalohydrin, the compound represented by formula (1) can be synthesized. Note that the term "equivalent" refers to the molar equivalent to the functional groups (hydroxyl group and carboxy group) possessed by the compound having the skeleton shown in formula (2), and the same applies below.
Furthermore, from the viewpoint of reducing the number of n and synthesizing the compound represented by formula (1) where n is small, preferably 0, in a high yield, it is preferable that the amount of epihalohydrin added is in large excess. . Specifically, it is preferably 2 equivalents or more, more preferably 5 equivalents or more, and still more preferably 8 equivalents or more.
In addition, from the viewpoint of making it easier to remove unreacted epihalohydrin after the reaction and increasing production efficiency, the amount of epihalohydrin added is preferably 50 equivalents or less with respect to the functional group of the compound shown in formula (2), It is more preferably 30 equivalents or less, still more preferably 20 equivalents or less, even more preferably 15 equivalents or less.

As a raw material compound, formula (2-1), formula (2-2) or formula (2-3) (however, in formula (2-3), R ¹⁶ and R ¹⁷ are -COOR ¹¹ and -COOR ¹³ , respectively) ), R ¹¹ and R ¹³ are hydrogen atoms (especially when using any of the compounds of formulas (2-4) to (2-6) as raw materials), and n When increasing the number of epihalohydrin, the amount of epihalohydrin added may be reduced, for example, 2 equivalents or less. When R ¹¹ and R ¹³ are hydrogen atoms, if the amount of epihalohydrin added is reduced, oligomerization of the compound having the skeleton shown in formula (2) and epihalohydrin will proceed more easily. -1) or the compound represented by formula (1-2) can be easily obtained.

The reaction between the compound having the skeleton shown in formula (2) above and epihalohydrin is preferably carried out in the presence of a catalyst. Examples of the catalyst include quaternary ammonium salts such as benzyltriethylammonium chloride, benzyltriethylammonium bromide, tetrabutylammonium fluoride, and tetrabutylammonium bromide. One type of catalyst may be used alone, or two or more types may be used in combination. The amount of the catalyst added is preferably 0.01 to 2 mol, more preferably 0.05 to 1 mol, and still more preferably 0.1 to 0.0 mol, per mol of the compound having the skeleton shown in formula (2). It is 5 moles.

The above reaction may be carried out in the presence of a solvent, or may be carried out without a solvent. The compound having the skeleton shown in formula (2) can be appropriately diluted with epihalohydrin by using a large excess of epihalohydrin as described above, and the above reaction can be carried out appropriately even if the reaction is carried out without a solvent or with a small amount of solvent. can proceed. As the reaction solvent, aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, halogen solvents, ester solvents, ether solvents, etc. can be used.
The reaction in the presence of the above catalyst is carried out at, for example, 40 to 150°C, preferably 60 to 120°C, for example, for 30 minutes to 24 hours, preferably for 2 to 12 hours.

Furthermore, in this production method, it is preferable to add a basic compound to the reaction system in addition to the above catalyst. By adding a basic compound, dehydrohalogenation progresses more easily, making it possible to improve the yield of the desired epoxy resin. It is preferable that the basic compound is reacted for a certain period of time in the presence of the above-mentioned catalyst, then added to the reaction system, and further reacted for a certain period of time. The reaction after addition of the basic compound is carried out at, for example, -10 to 30°C, preferably 0 to 15°C, for example, 10 minutes to 24 hours, preferably 30 minutes to 12 hours.

The basic compound used is not particularly limited as long as it functions as a base. Specifically, lithium hydroxide, sodium hydroxide, potassium hydroxide, cesium hydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, lithium hydride, sodium hydride, potassium hydride, lithium carbonate, sodium carbonate. , potassium carbonate, cesium carbonate, magnesium carbonate, calcium carbonate, barium carbonate, lithium alkoxide, sodium alkoxide, potassium alkoxide, and other metal bases. Among these, it is preferable to use at least one of sodium hydroxide and potassium hydroxide in terms of economy and availability.
The basic compound is not particularly limited, but may be added to the reaction system, for example, in the form of an aqueous solution.
The amount of the basic compound added may be, for example, more than 1 equivalent, preferably 1.5 to 20 equivalents, and more preferably It is 2 to 15 equivalents.

In this production method, the target epoxy resin is purified by distilling off epihalohydrin, distilling off the reaction solvent used as necessary, and extracting the target epoxy resin and water-soluble mixture using water and a hydrophobic solvent. General unit operations such as separation of chemical compounds, distillation of extraction solvent, distillation, etc., or a suitable combination of these can be carried out.

In the epoxy resin of the present invention, at least a part of the raw materials can be produced from biomass, and an epoxy resin with a high biomass ratio can be obtained. Specifically, dihydroxytruxylic acid represented by formula (2-4) is obtained by obtaining paracoumaric acid from a biomass-derived compound such as L-tyrosine through microbial synthesis, and photodimerizing paracoumaric acid as described above. Obtainable. Similarly, the compounds represented by formulas (2-5) to (2-7) can also be produced from biomass as described above. Therefore, the skeleton represented by formula (1) of the present invention can be derived from biomass, particularly from a compound synthesized by microorganisms. Among these, it is preferable that the structural unit derived from dihydroxytruxylic acid in formula (1-2) be derived from biomass, particularly from a compound synthesized by microorganisms.
In addition, the method for obtaining paracoumaric acid by microbial synthesis has stereoselectivity and can obtain paracoumaric acid in high yield, and the subsequent dimerization and epoxidation are also relatively simple. The epoxy resin having the skeleton represented by formula (1) can be easily produced even though it is a compound that can be obtained from biomass.

Furthermore, in the compounds shown in formulas (1-1) to (1-3), R ¹ and R ³ may be derived from a monohydroxy compound, and R ² may be derived from a dihydroxy compound; It is preferable that the monohydroxy compound and the dihydroxy compound are derived from biomass. By using these as biomass-derived epoxy resins, it is possible to obtain epoxy resins with even higher biomass content. Specifically, biomass-derived methanol, ethanol, and butanol are known as monohydroxy compounds, and biomass-derived ethylene glycol, 1,3-propanediol, and 1,4-butanediol are known as dihydroxy compounds. etc. are known, and by using these, the biorate of epoxy resin can be further improved.

<Cured body>
The cured product of the present invention (hereinafter also referred to as "epoxy cured product") is obtained by curing the above-mentioned epoxy resin. The epoxy cured product is generally cured with a curing agent, and therefore is preferably a cured product of a curable composition containing an epoxy resin and a curing agent.
The curing agent that can be used in the epoxy cured product is not particularly limited as long as it can cure the epoxy resin, but compounds that react with the epoxy resin to form a three-dimensional network structure (network polymer) are preferred.
Specific curing agents include amine-based curing agents, acid anhydride-based curing agents, polyamide resins that are condensates of dimer or trimer acids and polyamines, Lewis acids such as boron trifluoride-amine complexes, phenol or its like. Examples include derivatives. Further, as the curing agent, a mercapto curing agent can also be used.

Examples of the amine curing agent include polyamines such as aliphatic polyamines and aromatic polyamines. Examples of the aliphatic polyamines include ethylenediamine, diethylenetriamine, triethylenetetramine, dipropylenetriamine, tetraethylenepentamine, dimethylaminopropylamine, bishexamylenetriamine, cyclohexylaminopropylamine, aminoethylethanolamine, and monohydroxyethyl Diethylenetriamine, bishydroxyethyldiethylenetriamine, N-(2-hydroxypropyl)ethylenediamine, hexamethylenediamine, diethylene glycol bis(3-aminopropyl)ether, diethylaminopropylamine, 3,9-bis(3-aminopropyl)-2,4 , 8,10-tetrasoxaspiro[5,5]undecane, menthanediamine, isophoronediamine, 4,4'-methylenebis(cyclohexylamine), bis(4-amino-3-methylcyclohexyl)methane, N-aminoethyl Examples include piperazine.
Aromatic polyamines are amines having an aromatic ring, and specifically include various xylylene diamines such as phenylene diamine, diaminodiphenylmethane, diaminoanisole, toluene diamine, metaxylylene diamine, and diaminodiphenylsulfone.

Further, the amine curing agent may be an imidazole curing agent, an amidoamine curing agent, or the like. Examples of imidazole curing agents include 2-methylimidazole, 2-ethylimidazole, 2-undecylimidazole, 2,4-dimethylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, and 1,2-diethylimidazole. , 2-phenyl-4-methylimidazole, 2,4,5-triphenylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methyl Imidazole, 1-cyanoethyl-2-undecylimidazole, 1-benzyl-2-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-aryl-4,5-diphenylimidazole, 2,4-diamino- 6-[2'-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-phenyl-4-methyl-5-hydroxymethylimidazole, etc. Can be mentioned. Examples of amidoamine curing agents include dicyandiamide and the like.

Examples of acid anhydride curing agents include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, chlorendic anhydride, dodecynyl succinic anhydride, and methyltetrahydro Examples include phthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, and methylhexahydrophthalic anhydride represented by 4-methylhexahydrophthalic anhydride.
Examples of phenol derivatives include bisphenols and their derivatives such as bisphenol F and bisphenol A, trifunctional phenols and their derivatives such as tri(hydroxyphenyl)methane and tri(hydroxyphenyl)ethane, phenols such as phenol novolak, and formaldehyde. Examples include compounds obtained by reacting with.
Examples of mercapto curing agents include compounds with two mercapto groups in the molecule such as 1,4-bis(3-mercaptobutyryloxy)butane, and compounds with mercapto groups such as pentaerythritol tetrakis (3-mercaptobutyrate). Compounds having three or more can also be used.
The curing agents may be used alone or in combination of two or more.

Among the curing agents mentioned above, amine curing agents are preferred, and polyamines are particularly preferred. The polyamines preferably have a total of two or more primary amino groups and secondary amino groups in one molecule, and preferably have at least one primary amino group, and more preferably have a primary amino group. Have two or more. The total number of primary amino groups and secondary amino groups in one molecule of polyamines is not particularly limited, but is, for example, 8 or less, preferably 5 or less, more preferably 3 or less.

The blending amount of the curing agent is, for example, 1 to 100 parts by weight, preferably 2 to 50 parts by weight, based on 100 parts by weight of the epoxy resin. If it is above these lower limits, it can be properly cured. For example, when a three-dimensional network structure is formed, the structure becomes strong and mechanical properties and thermal properties tend to be good. In addition, by setting the amount to be below these upper limits, the amount of the curing agent can be prevented from increasing more than necessary, and mechanical properties and thermal properties tend to be good.
The blending amount of the curing agent should be adjusted according to the epoxy equivalent of the epoxy resin and, if an amine curing agent is used, the amount of active hydrogen in the amine curing agent (i.e., the hydrogen atom bonded to the nitrogen atom in the amino group). You can adjust it as appropriate. For example, the ratio of the number of active hydrogens to the number of epoxy groups may be adjusted to 1 or close to 1, specifically 0.5 to 2, preferably 0.75 to 1.5, more preferably It is 0.9 to 1.1.

The glass transition temperature (Tg) of the epoxy cured product measured with a differential scanning calorimeter is preferably 150° C. or higher. When the temperature is 150° C. or higher, thermal performance can be improved, and the heat resistance of the cured epoxy product can be improved. Further, the glass transition temperature (Tg) of the epoxy cured product is more preferably 160°C or higher, and still more preferably 170°C or higher. The glass transition temperature (Tg) of the epoxy cured product is not particularly limited, but is, for example, 300° C. or lower.
Further, from the same viewpoint, the glass transition temperature (Tg) of the epoxy cured product measured with a dynamic viscoelasticity device is preferably 150°C or higher, more preferably 160°C or higher, and even more preferably 170°C or higher. , for example, 300°C or less.

Although the epoxy cured product is not particularly limited, it can be produced by mixing an epoxy resin and a curing agent to obtain a curable composition, and heating as necessary. The heating temperature is not particularly limited, but is, for example, room temperature (23°C) to 300°C, preferably 40°C to 250°C, and heating within the above temperature range is for example 10 minutes to 13 hours, preferably 1 to 6 hours. good. The heating temperature may be increased stepwise as curing progresses. Further, the curable composition containing an epoxy resin and a curing agent may be diluted by adding a solvent or the like, or may contain other components as appropriate. In the case of diluting with a solvent, the solvent may be removed by appropriately drying the solvent by the above-mentioned heating.

The curable composition may contain a curing accelerator in addition to the epoxy resin and curing agent of the present invention.
A curing accelerator is a component that accelerates curing by a curing agent. For example, among the curing agents, dicyandiamide and the like have a high curing temperature when used alone, so a curing accelerator can be used to increase the curing activity of dicyandiamide and the like. Examples of the curing accelerator for dicyandiamide include urea-based, imidazole-based, tertiary amine-based, caprolactam, and the like. Among these, urea-based and imidazole-based are preferred, including 2,4-diamino-6-(2-methylimidazolyl-(1))-ethyl-s-triazine, 3-(3,4-dichlorophenyl)-1,1 -dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea) are more preferred. The content of the curing accelerator is, for example, about 0.1 to 10 parts by mass based on 100 parts by mass of the epoxy resin.

The epoxy resin and epoxy cured product of the present invention can be used in various fields, including, but not limited to, electrical fields, transportation fields, civil engineering fields, architecture fields, mechanical fields, medical fields, etc. be. The epoxy resin and epoxy cured product of the present invention can be used in various forms such as various molded products, adhesives, paints, fillers, films, powders, composite materials, and foams.
More specifically, adhesives for dissimilar materials, rubber-resin adhesives, well bonding applications, bonding between substrates and semiconductor elements such as die attach, flexible substrate adhesives such as bonding films, and various construction and civil engineering applications. Applications for adhesives such as adhesives, anti-fog paints, electrodeposition paints, anti-corrosion paints, floor coatings, other paints for architecture and civil engineering, sealing for covered electric wires, etc. It can be used for various purposes such as fiber reinforcement materials, fiber sizing agents, prepregs, electrical insulation materials and protective materials for electronic components, photosensitive resins, lens applications, and dental materials, but is not limited to these applications.

The epoxy resin-containing composition containing the epoxy resin of the present invention can contain various components depending on the intended use. In addition to the above-mentioned curing agents and curing accelerators, such components include resins other than the epoxy resin of the present invention, latex, fillers, pigments, silane coupling agents, surfactants, ultraviolet absorbers, and antioxidants. , stabilizers, plasticizers, leveling agents, antifoaming agents, antistatic agents, flame retardants, lubricants, dispersants and the like.
Below, compositions containing the epoxy resin of the present invention used for various purposes (hereinafter also referred to as "epoxy resin-containing compositions") and compositions containing components derived from the epoxy resin of the present invention will be explained in more detail. However, each of the following compositions may contain components other than those specifically explained below, as necessary.

(Adhesive application)
For example, when used as an adhesive, the epoxy resin-containing composition may contain an epoxy resin and a curing agent. From this point of view, for example, polymer fine particles may be contained. When containing polymer fine particles, the adhesive is preferably used for dissimilar material adhesive applications in fields such as automobiles, and for well bond applications. The dissimilar materials used in dissimilar adhesive applications include two types selected from various materials such as various steel materials, aluminum, aluminum alloys, fiber reinforced plastic (FRP) plates such as carbon fiber and glass fiber, and carbon fiber reinforced plastic (CFRP). Examples include combinations. In addition to the epoxy resin of the present invention, the epoxy resin-containing composition used for the adhesive application may contain an epoxy resin other than the epoxy resin of the present invention.

The polymer fine particles are preferably polymer fine particles having a core-shell structure. A polymer particle having a core-shell structure refers to a polymer particle in which the molecular structure is different between the central part (core part) and the outer peripheral part (shell part).
Examples of the components constituting the core part of the polymer fine particles having a core-shell structure include butadiene rubber (BR), acrylic rubber (ACM), silicone rubber (Si), butyl rubber (IIR), nitrile rubber (NBR), and styrene-butadiene rubber. (SBR), isoprene rubber (IR), ethylene propylene rubber (EPR), and the like. Among them, butadiene rubber is preferred. It is preferable that the component constituting the shell part of the polymer fine particles having a core-shell structure is graft-polymerized to the above-mentioned core part and covalently bonded to the polymer constituting the core component. Examples of the components constituting the shell portion include acrylic ester monomers, methacrylic ester monomers, and aromatic vinyl monomers.
The content of the polymer fine particles is, for example, 1 to 100 parts by weight, preferably 2 to 80 parts by weight, and more preferably 4 to 60 parts by weight, based on 100 parts by weight of the epoxy resin contained in the curable composition. Polymer fine particles having a core-shell structure may be used alone, or two or more types may be used in combination.

In the above-mentioned adhesive for dissimilar material adhesive use or well bond use, the epoxy resin-containing composition preferably contains dicyandiamide, although the curing agents listed above are used as appropriate. The content of the curing agent is preferably 0.01 to 30 parts by weight, more preferably 0.1 to 25 parts by weight, and even more preferably 1 to 20 parts by weight, based on 100 parts by weight of the epoxy resin.
Moreover, when using the said adhesive for well bonding, it is preferable that the epoxy resin containing composition contains blocked urethane. Blocked urethane is an elastomer type compound containing a urethane group and/or a urea group, and has an isocyanate group at the end of various blocks in which all or part of the terminal isocyanate group has an active hydrogen group. Compounds capped with agents are contemplated. Particularly preferred is a compound in which all of the terminal isocyanate groups are capped with a blocking agent. Specific examples of blocked urethanes include compounds described in International Publication No. 2016/163491.
The content of blocked urethane in the epoxy resin-containing composition is preferably 1 to 50 parts by weight, more preferably 2 to 40 parts by weight, and even more preferably 5 to 30 parts by weight, based on 100 parts by weight of the epoxy resin.

The epoxy resin-containing composition may also be used as a rubber-resin adhesive in tires and the like. An example of the rubber-resin adhesive includes, in addition to the epoxy resin of the present invention, a curable composition containing synthetic rubber latex.
Synthetic rubber latexes include, but are not particularly limited to, those containing unsaturated dienes, such as styrene-butadiene copolymer rubber latex, vinylpyridine-styrene-butadiene copolymer rubber latex, and carboxyl group-modified styrene. -Butadiene copolymer rubber latex, nitrile rubber latex, chloroprene rubber latex, etc. can be mentioned. These may be used alone or in combination of two or more.
In the epoxy resin-containing composition used for the rubber-resin adhesive, the content of the synthetic rubber latex is not particularly limited, but is, for example, 25 to 80% by mass, preferably 35% by mass, based on solid content. ~75% by weight, more preferably 55-75% by weight.

Furthermore, the curable composition containing the synthetic rubber latex preferably further contains a water-soluble carbodiimide. Water-soluble carbodiimide refers to a carbodiimide that is soluble in water, and includes carbodiimides that are water-based and partially water-soluble. The water-soluble carbodiimide is a compound having carbodiimide (chemical formula: -N=C=N-) and a hydrophilic segment in the molecule. Water-soluble carbodiimide can be used as a dehydration condensation agent capable of forming an ester bond or an amide bond between a COOH group and an OH group or an amino group of a compound contained in an aqueous solution. For example, 1-ethyl-3-(3-(dimethylaminopropyl)carbodiimide (WSC) activates carboxyl groups, and its active intermediates can react with amino and hydroxyl groups to form amides and esters. Are known.

It is presumed that the water-soluble carbodiimide can coat the surface of synthetic rubber latex containing an unsaturated diene while crosslinking, and can be combined with the epoxy resin of the present invention to bond the resin of the adherend to the rubber. Ru.
The water-soluble carbodiimide is preferably a water-soluble salt such as a hydrochloride or a sulfate. More specifically, the water-soluble carbodiimide includes 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC); 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide-meth-p -Water-soluble salts of 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide such as toluene sulfate; 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmol Examples include triazine condensing agents such as phorinium chloride (DMT-MM), and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) is preferably used.
In the thermosetting composition used as a rubber-resin adhesive, the content of water-soluble carbodiimide is not particularly limited, but is preferably 0.1 to 15% by mass on a solid content basis. It is more preferably 0.3 to 10% by weight, even more preferably 0.5 to 7% by weight, even more preferably 0.5 to 5% by weight.

Further, the epoxy resin of the present invention used in the rubber-resin adhesive may have two or more epoxy groups in one molecule, but preferably contains four or more epoxy groups in one molecule. It's good to do that.
In the epoxy resin-containing composition of the rubber-resin adhesive, the content of the epoxy resin is not particularly limited, but is preferably 0.1 to 40% by mass on a solid content basis, and It is preferably 0.4 to 40% by weight, particularly preferably 1.0 to 30% by weight.
The epoxy resin-containing composition for the rubber-resin adhesive is not particularly limited, but each component is preferably dispersed or dissolved in water and used as a dispersion.

In adhesive applications, it may be used in electronic equipment applications, for example, in applications where a base material and a semiconductor element are bonded together. More specifically, it may be used for die attach purposes, and it may also be used as a silver paste material, for example, with silver particles added thereto.
When used as a silver paste material, the epoxy resin-containing composition may include silver particles, the epoxy resin of the present invention, and a curing agent, and the composition is used after being diluted with a solvent. Good. The epoxy resin-containing composition may contain epoxy resins other than the epoxy resin of the present invention. Further, as the curing agent, phenol derivatives and dicyandiamide are preferable, and these may be used in combination.
In the epoxy resin-containing composition, the content of silver particles is, for example, 70 to 98% by mass, preferably 75 to 95% by mass, based on solid content. Further, the content of the epoxy resin is, for example, 1 to 20% by mass, preferably 2 to 15% by mass, based on solid content. Further, the content of the curing agent is, for example, 0.1 to 1.5% by mass, preferably 0.2 to 1.0% by mass.

When used as an adhesive, it may also be used for flexible substrates. As an adhesive for a flexible substrate, it is used, for example, to bond a copper foil and a polyimide film constituting the substrate, and may be used, for example, as a bonding film.
The epoxy resin-containing composition for flexible substrates is preferably a curable resin composition containing the epoxy resin of the present invention and a curing agent, and may also contain epoxy resins other than the epoxy resin of the present invention, or epoxy resins other than the epoxy resin of the present invention. It may contain a resin, and such resins include polyester polymers such as polyester polyurethane resins. The polyester polyurethane resin is preferably a resin obtained by reacting at least a polyester polyol, a polyisocyanate, and a chain extender such as a diol compound other than the polyester polyol as raw materials. Further, in addition to the polyester polyurethane resin, a resin having a carboxy group or a carboxylic acid anhydride structure may be contained.
Further, as the curing agent, those mentioned above may be used as appropriate, but imidazole derivatives such as imidazole silane compounds may also be used in addition to those mentioned above.
Furthermore, the above-described epoxy resin-containing composition for flexible substrates may contain an organic filler, a metal filler, an inorganic filler other than the metal filler, and the like.
In the epoxy resin-containing composition used for the above flexible substrate, the content of the epoxy resin is preferably 1 to 60% by mass, and preferably 2 to 40% by mass, based on the total amount of components other than the filler. %, and even more preferably 3 to 20% by mass.

(Paint application)
The epoxy resin of the present invention may be used for paint purposes, or may be used as a binder resin for paints. Specifically, when used as an anti-fog coating, for example, it may be used in a coating composition containing the epoxy resin of the present invention and silica particles. The present coating composition may contain a silane coupling agent and the like as appropriate. When used as an anti-fog coating, the coating composition is preferably used as a dispersion by dispersing or dissolving each component in a liquid medium such as water. Further, the binder resin may include an epoxy resin other than the epoxy resin of the present invention or a resin other than the epoxy resin.
As the silica particles, water-dispersed silica is preferred, and colloidal silica or the like is preferably used. In addition, examples of the liquid medium include water and organic solvents, preferably water or a mixed solvent of water and an organic solvent. In the case of a mixed solvent, the organic solvent may be any organic solvent as long as it can disperse silica. For example, ethylene glycol monobutyl ether may be used. In the above coating composition, the content of the epoxy resin may be 0.1 to 1000 parts by mass, 0.5 to 500 parts by mass, and 1 to 100 parts by mass, based on 100 parts by mass of silica particles. It may be up to 100 parts by mass.

(For electrodeposition coating)
For example, when used in electrodeposition coating applications, an epoxy resin may be reacted with an amine and used as an aminated epoxy resin. Specific examples of amines include primary amines such as butylamine, octylamine, and monoethanolamine; secondary amines such as diethylamine, dibutylamine, methylbutylamine, diethanolamine, and N-methylethanolamine; and complex amines such as diethylenetriamine. Can be mentioned. The reaction of the above-mentioned primary amine can be controlled by forming a ketimine group using a ketone compound and forming a so-called block. Further, as the amine, a tertiary amine may be used, and specific examples thereof include triethylamine, N,N-dimethylbenzylamine, and N,N-dimethylethanolamine.
The coating composition for electrodeposition coating may contain, for example, an aminated epoxy resin and a curing agent such as a blocked polyisocyanate curing agent, and may further contain a pigment dispersion paste if necessary. The pigment dispersion paste includes a pigment dispersion resin and a pigment. The coating composition for electrodeposition coating may be used as an emulsion or the like.

(Anti-corrosion paint)
In coating applications, the coating composition may be a cured composition containing the epoxy resin of the present invention and a curing agent. Such a coating composition may contain an epoxy resin other than the epoxy resin of the present invention, a pigment or a pigment dispersant, and a silane coupling agent or the like to improve adhesion. May contain. Further, it may generally be used after being diluted with an organic solvent. A coating composition containing an epoxy resin and a curing agent is preferably used, for example, as an anticorrosive coating composition, and particularly preferably used for anticorrosion of ships. In the coating composition, the content of the epoxy resin is preferably 1 to 60% by mass, more preferably 5 to 50% by mass, based on solid content.

(floor coating agent)
The epoxy resin of the present invention may be used in architecture and civil engineering applications, for example, as a floor coating agent. The epoxy resin-containing composition used as a floor coating agent preferably contains the epoxy resin of the present invention and a curing agent, and further preferably contains an inorganic filler. As the inorganic filler, known inorganic fillers used as flooring agents such as carbon nanotubes, silica, silica sand, barite, calcium carbonate, and talc may be used. In addition to these inorganic fillers, pigments used as colorants may also be appropriately blended. Furthermore, the epoxy resin may contain epoxy resins other than those of the present invention.
In the epoxy resin-containing composition for floor coating, the content of the inorganic filler is, for example, about 1 to 1000 parts by mass, preferably 10 to 200 parts by mass, more preferably 20 to 200 parts by mass, based on 100 parts by mass of the epoxy resin. It is 100 parts by mass.
Of course, the epoxy resin-containing composition may be used in construction and civil engineering applications other than as a floor coating, and may also be used as a tank paint, a pipe interior paint, an exterior paint, and the like. It may also be used as an adhesive in architecture and civil engineering applications, for example, for bonding various structures.

(Encapsulant use)
When the epoxy resin of the present invention is used as a sealing material, preferably for sealing a covered electric wire, it may be used, for example, as a curable composition containing an epoxy resin and a curing agent. As the curing agent used in the sealant application, the above-mentioned curing agents can be used as appropriate, but amine-based curing agents and mercapto-based curing agents can be preferably used. Moreover, it is preferable that the curable composition used as a sealant contains a silane coupling agent.

(fiber sizing agent)
When the epoxy resin of the present invention is used as a fiber sizing agent, it may be used in combination with a polyester resin having a sulfonic acid group. As the polyester resin having a sulfonic acid group, an aromatic polyester resin, an aliphatic polyester resin, etc. can be used, but it is preferable to use an aromatic polyester resin. The aromatic polyester resin preferably has a structural unit derived from an aromatic dicarboxylic acid such as isophthalic acid or terephthalic acid.
In addition, the epoxy resin-containing composition for the fiber sizing agent preferably contains a surfactant in addition to the above-mentioned epoxy resin and polyester resin having a sulfonic acid group. Surfactants are preferred. Aromatic nonionic surfactants include polyoxyalkylene alkylphenyl ether, polyoxyalkylene styrenated phenyl ether, polyoxyalkylene benzylphenyl ether, polyoxyalkylene cumyl phenyl ether, polyoxyalkylene naphthylphenyl ether, polyoxyalkylene Examples include styrenated phenyl ethers (alkylphenyl ethers), and among these, polyoxyalkylene styrenated phenyl ethers such as polyoxyethylene styrenated phenyl ethers are preferred.
The epoxy resin-containing composition for fiber sizing agent may contain epoxy resins other than the epoxy resin of the present invention.
The epoxy resin-containing composition for a fiber sizing agent is preferably used as an aqueous composition, for example, as an aqueous dispersant.
In the epoxy resin-containing composition for a fiber sizing agent, the content of the epoxy resin is, for example, 75 to 95% by mass, and preferably 80 to 95% by mass, based on the solid content.

(Prepreg application)
The epoxy resin of the present invention may be used for prepreg applications, and is preferably used as a matrix resin to be impregnated into fiber materials such as reinforcing fibers used for prepreg applications.
When used as a matrix resin, the epoxy resin-containing composition may be a curable composition and may contain the epoxy resin of the present invention and a curing agent.
In addition, in the epoxy resin-containing composition, the epoxy resin of the present invention may be used alone as a resin component, but it may also be used in combination with other resin components, and epoxy resins other than the epoxy resin of the present invention, polyfunctional A (meth)acrylate compound, a cyanate ester resin containing two or more cyanato groups, etc. may be contained. Moreover, it is also preferable that the epoxy resin-containing composition contains a thermoplastic resin. Furthermore, the epoxy resin-containing composition used for prepreg applications may contain a flame retardant. Examples of the flame retardant include phosphorus-containing compounds such as phosphoric acid esters, nitrogen-containing compounds such as red phosphorus, melamine, melamine cyanurate, and melamine isocyanurate, metal hydroxides, metal oxides, and the like.
In the epoxy resin-containing composition used for prepreg applications, the content of epoxy resin is preferably about 20 to 99% by mass, more preferably about 50 to 80% by mass. Further, the content of the curing agent is preferably 1 to 25% by mass, more preferably 2 to 20% by mass.

(Electrical insulation materials and protective materials)
The epoxy resin of the present invention may be used in electronic substrates and the like, and specifically, it may be used as a protective material and an electrically insulating material for forming an electrically insulating layer.
When used for electrical insulation materials or protective materials, a curable resin composition containing a filler in addition to the epoxy resin of the present invention and a curing agent is preferable. The filler is preferably insulating. Such fillers include silica, alumina, aluminum nitride, boron nitride, silicon carbide, silicon nitride, and the like. Further, as the filler, fillers other than the above-mentioned inorganic fillers may be used, or organic fillers may be used. In the curable resin composition, the filler content is, for example, 50 to 90% by mass, preferably 65 to 85% by mass, based on solid content.

Curable resin compositions used for electrical insulation materials and protective materials may contain resins other than the epoxy resin of the present invention, for example, may contain rubbery polymer compounds such as conjugated diene rubber. Good too. The content of the rubbery polymer compound is, for example, 30 to 70% by mass, preferably 40 to 60% by mass, based on the solid content of all components other than the filler. Further, it may contain an epoxy resin other than the epoxy resin of the present invention, and may contain a thermosetting resin other than the epoxy resin, such as a phenoxy resin. It may also contain a silane coupling agent.
In the curable resin composition used for electrical insulation materials and protective materials, the content of epoxy resin is, for example, 20 to 70% by mass, preferably 25 to 40% by mass, based on the solid content of the total amount of components other than fillers. .

(Photosensitive resin)
When used as an electrical insulation material or protective material for electronic boards, the epoxy resin-containing composition may be used as a photosensitive resin composition, and in such a case, in addition to the epoxy resin, It may be a composition containing a photosensitive resin such as a carboxyl group-containing photosensitive resin, a photopolymerization initiator, a reactive diluent, a photosensitive monomer, a filler, and the like.
Furthermore, when used as a photosensitive resin composition, it may be used for purposes other than the above-mentioned protective material for electronic substrates and electrical insulating material. When used in a photosensitive resin composition, the epoxy resin of the present invention may be used in combination with a photoacid generator such as iodonium salts, sulfonium salts, and pyridinium salts. The photoacid generator is an agent that generates acid upon irradiation with light, and the epoxy resin is preferably polymerized by the acid generated by decomposition of the photoacid generator.
In addition, when used as a photosensitive resin composition as described above, applications include, but are not limited to, dental applications, and more specifically, filling and restoring materials used for repairing damaged teeth. , lining materials for denture bases, hybrid ceramics for dental crown restorations, etc. Further, it may be used for lens applications as described below.

(Lens use)
In lens applications, the epoxy resin of the present invention may be used in combination with resin components such as epoxy resins other than the epoxy resin of the present invention and oxtacene compounds. In addition to the resin, other epoxy resins, oxtacene compounds, etc. may be contained. Examples of other epoxy resins include diglycidyl ether compounds having a bisphenol skeleton, bifunctional alicyclic epoxy compounds having no bisphenol skeleton, and trifunctional or higher functional epoxy compounds having an isocyanurate ring structure. Further, when used for lens applications, the epoxy resin-containing composition is preferably a photosensitive resin composition, and may contain, for example, the above-mentioned photoacid generator.
The uses and specific formulations for each use explained above are only examples, and may be used for purposes other than those explained above, and the formulation of each composition for each use may be different from the above-mentioned formulation. Anything other than that is fine.

The present invention will be explained below with reference to Examples, but the present invention is not limited in any way by these Examples. In addition, each measurement condition in the following examples is as follows.
<Measurement conditions>
[ ^1H -NMR spectrum measurement]
Measurement was performed at 23° C. using an NMR measuring device “ECX-400” manufactured by JEOL Ltd., using heavy dimethyl sulfoxide (heavy DMSO) or THF as a solvent.

[Glass transition temperature (Tg)]
Using a differential scanning calorimeter (product name: "DSC-60") manufactured by Shimadzu Corporation, measurements were performed under argon atmosphere at a heating rate of 10°C/min, and the midpoint of the baseline displacement was determined as the glass transition temperature. did. At this time, the temperature was raised to 250°C at a rate of 10°C/min, the temperature was lowered to 30°C, and the glass transition temperature was measured when the temperature was raised again.
Using a dynamic viscoelasticity device (trade name "Rheogel-E4000") manufactured by UBM Co., Ltd., it was measured under a nitrogen atmosphere at a temperature increase of 3°C/min, and the peak top temperature of tan δ was taken as the glass transition temperature. .

Synthesis example 1
[Synthesis of paracoumaric acid dimer]
Paracoumaric acid (manufactured by Tokyo Kasei Co., Ltd.) was suspended in hexane, and the suspended solution was irradiated with UV light using an incandescent mercury lamp. The double bond at the beta position of paracoumaric acid was cleaved by UV irradiation, and the molecules recombined with each other, resulting in dimerization. After removing hexane from the reaction solution, it was resuspended in ethanol and filtered. The powder remaining on the filtration membrane was obtained as paracoumaric acid dimer. In addition, when the powder remaining on the filter membrane was subjected to ¹ H-NMR measurement, it was confirmed that it was paracoumaric acid dimer (4,4'-dihydroxytruxylic acid) shown by formula (2-1). did it.

[Synthesis of epoxy resin]
Example 1
5 g of the paracoumaric acid dimer obtained in Synthesis Example 1 was suspended in 50 ml of methanol and 0.3 ml of concentrated sulfuric acid, and reacted at 80° C. for 6 hours. After the reaction was completed, methanol was removed and the mixture was dried. The dried methyl ester was dissolved in 50 ml of ethyl acetate, and then washed twice with 5% by mass NaHCO ₃ solution. It was further washed twice with saturated brine, and the ethyl acetate layer was collected. After dehydrating the obtained organic phase by adding anhydrous magnesium sulfate, ethyl acetate and remaining volatile components were removed to obtain 3.31 g of methyl ester (dimethyl 4,4'-dihydroxytruxylate) (yield: 61 .0%). The structure was identified by ¹ H-NMR measurement in THF. Figure 1 shows the ¹ H-NMR spectrum.

1 g of the methyl ester obtained by the above method, 5.2 g of epichlorohydrin (10 equivalents to the methyl ester), and 0.18 g of tetrabutylammonium bromide were reacted at 100° C. for 5 hours. After the reaction was completed, 2.5 ml of a 40% by mass aqueous sodium hydroxide solution was added dropwise to the solution while cooling it with ice, and then the reaction was allowed to proceed in ice-cold water for 1 hour. After the reaction, 20 ml of ion-exchanged water was added to dissolve the precipitated salt, and then 30 ml of ethyl acetate was added and mixed thoroughly to separate the aqueous phase. After dehydrating the obtained organic phase by adding anhydrous magnesium sulfate, ethyl acetate and remaining volatile components were removed to obtain 0.57 g of the desired epoxy resin (yield 44.0%). The structure was identified by ¹ H-NMR measurement in THF. Figure 2 shows the ¹ H-NMR spectrum. Moreover, the reaction formula in Example 1 is shown below.

[Preparation of cured epoxy body]
Example 2
4.64 g of the epoxy resin obtained in Example 1 and 0.85 g of isophorone diamine were mixed. Thereafter, a cured product was produced by heating at 100°C for 1 hour, at 160°C for 1 hour, and then at 200°C for 1 hour. When the obtained cured product was finely crushed and its Tg was measured using a differential scanning calorimeter (DSC), the Tg was 165° C., indicating good heat resistance.

Example 3
[Synthesis of epoxy resin]
5 g of the paracoumaric acid dimer obtained in Synthesis Example 1, 56.4 g of epichlorohydrin (10 equivalents to the paracoumaric acid dimer), and 1 g of tetrabutylammonium bromide were reacted at 100° C. for 5 hours. After the reaction was completed, 2.5 ml of a 40% by mass aqueous sodium hydroxide solution was added dropwise to the solution while cooling it with ice, and then the reaction was allowed to proceed in ice-cold water for 1 hour. After the reaction, 20 ml of ion-exchanged water was added to dissolve the precipitated salt, and then 30 ml of ethyl acetate was added and mixed thoroughly to separate the aqueous phase. After dehydrating the obtained organic phase by adding anhydrous magnesium sulfate, ethyl acetate and remaining volatile components were removed to obtain 5.42 g of the desired epoxy resin (yield 63.3%). The structure was identified by ¹ H-NMR measurement in heavy DMSO, and it was confirmed that the desired epoxy resin had been synthesized. The reaction formula in Example 3 is shown below.

[Preparation of cured epoxy body]
Example 4
5.52 g of the epoxy resin obtained in Example 3 and 1.70 g of isophoronediamine were mixed. Thereafter, a cured product was produced by heating at 100°C for 1 hour, at 160°C for 1 hour, and then at 200°C for 1 hour. When the obtained cured product was finely crushed and the Tg was measured using a differential scanning calorimeter (DSC), no clear Tg could be shown. Therefore, measurement was performed using a dynamic viscoelasticity method (DMA), and the Tg could be read as 251° C. from the peak top temperature of tan δ. It showed good heat resistance.

Comparative example 1
A petroleum-derived bisphenol A epoxy resin (trade name "jER828", manufactured by Mitsubishi Chemical Corporation) was mixed with isophorone diamine as a curing agent so that the ratio of epoxy group to NH group was 1:1. Curing was performed under the same conditions to produce a cured product. The obtained cured product was cut into pieces and the Tg was measured using a differential scanning calorimeter (DSC), and the result was that the Tg was 152°C.

Claims

An epoxy resin having a skeleton represented by the following formula (1).

In addition, in formula (1), R 4 and R 5 are each independently a hydrogen atom, an alkoxy group, or -OG. * may be a binding site with another structure. G represents a glycidyl group.
The epoxy resin according to claim 1, having a structure represented by the following formula (1-1).

In addition, in formula (1-1), R 1 and R 3 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, which may have a heteroatom, or a glycidyl group, and R 2 is It is a divalent hydrocarbon group having 2 to 20 carbon atoms that may have a heteroatom. In each benzene ring, one of R 4 and R 5 is a hydrogen atom, and the other is a hydrogen atom, -OCH 3 or -OG. n is an integer from 0 to 100.
The epoxy resin according to claim 1, having a structure represented by the following formula (1-2).

In addition, in formula (1-2), R 1 and R 3 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, which may have a hetero atom, or a glycidyl group, and R 2 is It is a divalent hydrocarbon group having 2 to 20 carbon atoms that may have a heteroatom. n is an integer from 0 to 100.
The epoxy resin according to claim 2 or 3, wherein R 1 and R 3 are glycidyl groups, and n is 0.
The epoxy resin according to claim 2 or 3, wherein R 1 and R 3 are alkyl groups having 1 to 6 carbon atoms, and n is 0.
The epoxy resin according to claim 2 or 3, wherein R 1 and R 3 are methyl groups.
The epoxy resin according to claim 1, having a structure represented by the following formula (1-3).

In each benzene ring of formula (1-3), one of R 4 and R 5 is a hydrogen atom, and the other is a hydrogen atom, -OCH 3 or -OG. Further, R 6 is a hydrogen atom, -COOG, or -COOR 1 , and R 7 is a hydrogen atom, -COOG, or -COOR 3 . R 1 and R 3 are alkyl groups.
The epoxy resin according to any one of claims 1 to 3 and 7, wherein the skeleton represented by formula (1) is derived from biomass.
A cured product obtained by curing the epoxy resin according to any one of claims 1 to 3 and 7.
A method for producing an epoxy resin, which comprises reacting a compound having a skeleton represented by the following formula (2) with epihalohydrin to obtain an epoxy resin.

In addition, in formula (2), R 14 and R 15 are each independently a hydrogen atom, an alkoxy group, or -OH. * may be a binding site with another structure.
The method for producing an epoxy resin according to claim 10, wherein the epoxy resin is obtained by reacting a compound represented by the following formula (2-1) with epihalohydrin.

In the above formula (2-1), R 11 and R 13 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms which may have a hetero atom. R 12 is a divalent hydrocarbon group having 2 to 20 carbon atoms which may have a heteroatom. In each benzene ring, one of R 14 and R 15 is a hydrogen atom, and the other is a hydrogen atom, -OCH 3 or -OH. m is an integer from 0 to 100.
The method for producing an epoxy resin according to claim 10, wherein the epoxy resin is obtained by reacting a compound represented by the following formula (2-2) with epihalohydrin.

In the above formula (2-2), R 11 and R 13 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms which may have a hetero atom. R 12 is a divalent hydrocarbon group having 2 to 20 carbon atoms which may have a heteroatom. m is an integer from 0 to 100.
The method for producing an epoxy resin according to claim 10, wherein the epoxy resin is obtained by reacting a compound represented by the following formula (2-3) with epihalohydrin.

In each benzene ring of formula (2-3), one of R 14 and R 15 is a hydrogen atom, and the other is a hydrogen atom, -OCH 3 or -OH. R 16 is a hydrogen atom or -COOR 11 , and R 17 is a hydrogen atom or -COOR 13 . R 11 and R 13 are each independently a hydrogen atom or an alkyl group.