Epoxy resin, cured body, and method for producing epoxy resin

Abstract

This invention provides a highly heat-resistant epoxy resin using biomass-derived compounds such as hydroxycinnamic acids as starting materials. [Solution] An epoxy resin represented by the following formula (I). JPEG2026122918000022.jpg5377 In the formula, m is an integer from 1 to 100, and R1 to R 10 These are independently H, a halogen atom, a hydroxyl group, or an organic group having 1 to 20 carbon atoms, at least one of R1 to R5 and R6 to R 10 At least one of them is independently a hydroxyl group or a glycidyloxy group. 11 and R 13 H is R 12 The compound is H, and has at least one glycidyloxy group in formula (I).

Description

[Technical Field]

[0001] The present invention relates to epoxy resin, a cured epoxy resin, and a method for producing epoxy resin. [Background technology]

[0002] Because petroleum is a finite resource and causes global environmental problems such as carbon dioxide emissions, the use of alternative resources has been increasingly sought in recent years. Biomass is attracting attention as an alternative resource to petroleum, and in recent years, the synthesis of epoxy resins from biomass has been investigated. For example, Patent Document 1 discloses the synthesis of epoxy resins by dimerizing 4-vinylsyringol and 4-vinylguaiacol, which can be produced from biomass, and then further glycidylating the resulting dimers with epichlorohydrin.

[0003] Furthermore, in recent years, the production of valuable substances using microorganisms with biomass as a starting material has also been considered. For example, it is known that hydroxycinnamic acids such as p-coumaric acid can be synthesized from L-tyrosine using microorganisms. Therefore, the effective utilization of hydroxycinnamic acids is being investigated. For example, Patent Document 2 discloses a method for synthesizing poly(hydroxystyrene) compounds using hydroxycinnamic acids as a starting material. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] French Public Gazette No. 3071836 [Patent Document 2] Special Publication No. 2009-545648 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, Patent Document 2 only describes a method for synthesizing poly(hydroxystyrene) compounds from hydroxycinnamic acids, and does not disclose a method for synthesizing epoxy resins using hydroxycinnamic acids as a starting material.

[0006] Furthermore, Patent Document 1 does not anticipate the use of hydroxycinnamic acids as a starting material, and therefore it is not possible to synthesize epoxy resins using hydroxycinnamic acids as a starting material. Moreover, Patent Document 1 only shows a method for synthesizing dimer compounds, making it difficult to provide epoxy resins that can achieve high crosslinking density, and furthermore, due to its structure, there are concerns about the generation of by-products during curing or synthesis. In addition, biomass-derived epoxy resins generally have lower heat resistance compared to petroleum-derived epoxy resins.

[0007] Therefore, the object of the present invention is to provide a highly heat-resistant epoxy resin using biomass-derived compounds such as hydroxycinnamic acids as starting materials. [Means for solving the problem]

[0008] The gist of this invention is as follows: [1] An epoxy resin represented by the following formula (I). [ka] (In equation (I), m is an integer from 1 to 100, and R1 to R 10 Each of these is an organic group having 1 to 20 carbon atoms, which may independently have a hydrogen atom, a halogen atom, a hydroxyl group, or a heteroatom, and at least one of R1 to R5 and R6 to R 10 At least one of these is independently a hydroxyl group or a glycidyloxy group. R 11 and R 13 is a hydrogen atom, and R 12 (where is a hydrogen atom or a group represented by the following formula (II), and formula (I) has at least one glycidyloxy group.) [ka] (In formula (II), n is an integer from 1 to 100, and R 14 ~R 18 are each independently a hydrogen atom, a halogen atom, a hydroxyl group, or an organic group having 1 to 20 carbon atoms which may have a hetero atom, and R 14 ~R 18 at least one of which is a hydroxyl group or a glycidyloxy group, R 19 is a hydrogen atom, and * indicates the bonding position in R 12 in formula (I).) (However, a compound in which m is 1, R3 and R8 are glycidyloxy groups, R2 and R7 are methoxy groups, and R1, R4 to R6, R9 to R 13 are hydrogen atoms, and a compound in which m is 1, R3 and R8 are glycidyloxy groups, R2, R4, R7 and R9 are methoxy groups, and R1, R5, R6 and R 10 ~R 13 are hydrogen atoms are excluded.) [2] The epoxy resin according to [1] above, wherein m is 2 or more in formula (I). [3] At least one of R1 to R5 is a hydroxyl group or a glycidyloxy group, the group adjacent to the hydroxyl group or the glycidyloxy group is other than a hydroxyl group, a glycidyloxy group and an alkoxy group, and R6~R 10 at least one of which is a hydroxyl group or a glycidyloxy group, the group adjacent to the hydroxyl group or the glycidyloxy group is other than a hydroxyl group, a glycidyloxy group and an alkoxy group, R 12 is a group represented by formula (II), R 14 ~R 18 at least one of which is a hydroxyl group or a glycidyloxy group, the group adjacent to the hydroxyl group or the glycidyloxy group is other than a hydroxyl group, a glycidyloxy group and an alkoxy group, the epoxy resin according to [1] or [2] above. [4] The epoxy resin according to any one of [1] to [3] above, wherein R 12 is a hydrogen atom. [5] R1~R 10Each of these is independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group, a glycidyloxy group, or a hydrocarbon group, and furthermore, R 12 If the group is represented by formula (II), then R 14 ~R 18 The epoxy resin according to any one of the above [1] to [4], wherein each is independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group, a glycidyloxy group, or a hydrocarbon group. [6] R3 and R8 are glycidyloxy groups, and R1, R2, R4~R7, and R9~R 13 An epoxy resin according to any of the above [1] to [5], wherein is a hydrogen atom. [7] The epoxy resin described in [6] above, wherein m is 1. [8] A method for producing epoxy resin, comprising heating a compound represented by the following formula (III) in the presence of a basic substance to obtain a hydroxystyrene polymer, and reacting the hydroxystyrene polymer with an epihalohydrin to obtain an epoxy resin. [ka] (In formula (III), R 21 ~R 25 Each of these is an organic group having 1 to 20 carbon atoms, which may independently contain a hydrogen atom, a halogen atom, a hydroxyl group, or a heteroatom, and R 21 ~R 25 At least one of them is a hydroxyl group. [9] A method for producing the epoxy resin according to [8] above, wherein a compound represented by formula (III) is heated in a mixed solvent of water and a specific organic solvent represented by the following formula (IV) in the presence of the basic substance to obtain the hydroxystyrene polymer. [ka] (In formula (IV), R 26 This is an organic group having 1 to 10 carbon atoms, which may contain heteroatoms.

[10] In equation (IV), R 26 The method for producing epoxy resin as described in [9] above, wherein the structure is represented by the following formula (V). [ka] (In formula (V), R 27 R is an alkyl group having 1 to 4 carbon atoms. 28 (where * indicates a hydrogen atom or methyl group, and * indicates the bond position to the hydroxyl group in formula (IV).)

[11] In equation (V), R 27 R is either a methyl group or an ethyl group, 28 A method for producing the epoxy resin described in

[10] above, wherein is a methyl group.

[12] The method for producing epoxy resin according to any one of [8] to

[11] above, wherein the basic substance is at least one of an alkali metal or alkaline earth metal hydroxide, carbonate, or bicarbonate.

[13] The method for producing an epoxy resin according to

[12] above, wherein the basic substance is an alkali metal hydroxide.

[14] A cured body obtained by curing an epoxy resin according to any of the epoxy resins described in [1] to [7] above, or an epoxy resin obtained by a method for producing an epoxy resin described in any of the epoxy resins described in [8] to

[13] above. [Effects of the Invention]

[0009] In this invention, a highly heat-resistant epoxy resin can be provided using biomass-derived compounds such as hydroxycinnamic acids as starting materials. [Brief explanation of the drawing]

[0010] [Figure 1] The 1H-NMR spectrum of the epoxy resin synthesized in Example 1 is shown. [Figure 2] The 1H-NMR spectrum of the compound that is the main component of the trimer of the HS oligomer synthesized in Production Example 1 is shown. [Figure 3] The HH COSY spectrum of the compound that is the main component of the trimer of the HS oligomer synthesized in Production Example 1 is shown. [Figure 4]The 1H-NMR spectrum of a compound that is a component of the trimer of the HS oligomer synthesized in Production Example 1 is shown. [Figure 5] The HH COSY spectrum of a compound that is a component of the trimer of the HS oligomer synthesized in Production Example 1 is shown. [Modes for carrying out the invention]

[0011] <Epoxy resin> The present invention will be described in more detail below using embodiments. An epoxy resin according to one embodiment of the present invention is represented by the following formula (I). [ka] In equation (I), m is an integer from 1 to 100, and R1 to R 10 Each of these is an organic group having 1 to 20 carbon atoms, which may independently have a hydrogen atom, a halogen atom, a hydroxyl group, or a heteroatom, and at least one of R1 to R5 and R6 to R 10 At least one of these is independently a hydroxyl group or a glycidyloxy group. R 11 and R 13 is a hydrogen atom, and R 12 is a hydrogen atom or a group represented by the following formula (II), and has at least one glycidyloxy group in formula (I).

[0012] [ka] In equation (II), n is an integer from 1 to 100, and R 14 ~R 18 Each of these is an organic group having 1 to 20 carbon atoms, which may independently contain a hydrogen atom, a halogen atom, a hydroxyl group, or a heteroatom, and R 14 ~R 18 At least one of them is a hydroxyl group or a glycidyloxy group, R 19 * is a hydrogen atom, and * is R in formula (I). 12 This shows the binding position. However, in the epoxy resin shown in formula (I), m is 1, R3 and R8 are glycidyloxy groups, R2 and R7 are methoxy groups, and R1, R4~R6, R9~R 13 A compound in which is a hydrogen atom, and m is 1, R3 and R8 are glycidyloxy groups, R2, R4, R7 and R9 are methoxy groups, and R1, R5, R6 and R 10 ~R 13 Excluding compounds in which the atom is a hydrogen atom.

[0013] Epoxy resins having the above structure can be synthesized using biomass-derived compounds such as hydroxycinnamic acids as starting materials, and can also have high heat resistance. The principle of high heat resistance is not entirely clear, but possible reasons include the fact that the compound shown in formula (I) has double bonds between aromatic compounds, which suppresses the movement of aromatic rings and thus improves heat resistance, or that the polymerization of the double bonds increases the crosslinking density and thus improves heat resistance. In addition, due to its structure, epoxy resins shown in formula (I) tend to suppress the formation of by-products during curing or synthesis.

[0014] Note that in equation (I), R is typically 12 and R 13 This is often a positional relationship that results in a transformer, for example, when manufactured using the manufacturing method described later, R 12 and R 13 It is basically a transformer. However, the epoxy resin shown in formula (I) may isomerize due to light irradiation, etc., R 12 and R 13 The cis position may also be the cis position. The epoxy resin is R 12 and R 13 Compounds that are trans and R 12 and R 13 It may also be a compound mixture in the cis state.

[0015] R1~R 10 , R 14 ~R 18 Examples of halogen atoms in this context include fluorine, chlorine, bromine, and iodine atoms. R1~R 10, R 14 ~R 18 The C1-C20 organic group which may have a heteroatom is a hydrocarbon group which may have a heteroatom. The hydrocarbon group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group which has an aromatic ring. The aliphatic hydrocarbon group may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group. Examples of heteroatoms include nitrogen atoms, sulfur atoms, oxygen atoms, halogen atoms, and phosphorus atoms. While not particularly limited, examples of heteroatoms include oxygen atoms constituting ether bonds, ester bonds, keto groups, alkoxy groups, and nitro groups; sulfur atoms constituting sulfonyl groups and thiol bonds; nitrogen atoms constituting nitro groups and cyano groups; and halogen atoms substituted for hydrogen atoms in hydrocarbon groups. Note that ether bonds may form cyclic ethers, and more specifically, epoxy groups. Heteroatoms may be located in the middle of a hydrocarbon chain or at its terminus. The number of carbon atoms in the above organic group is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 3. Preferred specific examples of the organic group are alkoxy groups, glycidyloxy groups, or hydrocarbon groups.

[0016] Among those mentioned above, R1~R 10 Each of these is preferably independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group, a glycidyloxy group, or a hydrocarbon group. Furthermore, if R8 is a hydroxyl group or a glycidyloxy group, R7 may be a group represented by the following formula (I-3). Compounds in which R7 is a group represented by the following formula (I-3) are usually produced together with other compounds in the manufacturing method described later. [ka] In formula (I-3), * indicates the bond position with the aromatic ring. 38 R is a hydroxyl group or a glycidyloxy group, 36 , R 37 , R 39 , R 40These are organic groups that may each independently have a hydrogen atom, a halogen atom, a hydroxyl group, or a heteroatom. Among them, R 36 , R 37 , R 39 , R 40 Each of these is preferably independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group, a glycidyloxy group, or a hydrocarbon group.

[0017] Furthermore, R 12 If is the group shown by formula (II), then R 14 ~R 18 Each of these is preferably independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group, a glycidyloxy group, or a hydrocarbon group. Compounds having the above structure can be easily synthesized using biomass-derived compounds such as hydroxycinnamic acids as starting materials.

[0018] Examples of alkoxy groups include alkoxy groups having 1 to 4 carbon atoms, such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, and tert-butoxy groups. Among these, the methoxy group is preferred. Furthermore, alkyl groups are preferred as hydrocarbon groups. Alkyl groups may be linear, branched, or cyclic. Specific examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, various pentyl groups, various hexyl groups, various heptyl groups, and various octyl groups. "Various" refers to various isomers including linear (n-), sec-, tert-, iso-, etc., and the same applies hereafter. In addition, alkyl groups may also have cyclic structures such as cyclohexyl groups. The alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, even more preferably 1 to 3 carbon atoms, and most preferably a methyl group. Among them, R1~R 10It is more preferable that each of these independently be a hydrogen atom, a hydroxyl group, a methoxy group, a glycidyloxy group, or a methyl group. 12 If is the group shown by formula (II), then R 14 ~R 18 It is more preferable that each of these is independently a hydrogen atom, a hydroxyl group, a methoxy group, a glycidyloxy group, or a methyl group.

[0019] Furthermore, it is preferable that at least one of R1 to R5 is a hydroxyl group or a glycidyloxy group, and that the group adjacent to the hydroxyl group or glycidyloxy group is other than a hydroxyl group, a glycidyloxy group, or an alkoxy group. In this case, it is more preferable that the group adjacent to the hydroxyl group or glycidyloxy group is a hydrogen atom, and it is even more preferable that the at least one of the hydroxyl groups or glycidyloxy groups is a glycidyloxy group. In this way, by ensuring that a hydroxyl group or glycidyloxy group is not adjacent to a hydroxyl group, glycidyloxy group, or alkoxy group within a single aromatic ring, intramolecular side reactions within the same aromatic ring can be suppressed during synthesis or curing. Similarly, R6~R 10 Preferably, at least one of the groups is a hydroxyl group or a glycidyloxy group, and the group adjacent to the hydroxyl group or glycidyloxy group is other than a hydroxyl group, a glycidyloxy group, or an alkoxy group. In this case, the group adjacent to the hydroxyl group or glycidyloxy group is more preferably a hydrogen atom, and it is more preferable that the at least one of the hydroxyl groups or glycidyloxy groups is a glycidyloxy group. Furthermore, R 12 If is the group shown by formula (II), then R 14 ~R 18 Preferably, at least one of the groups is a hydroxyl group or a glycidyloxy group, and the group adjacent to the hydroxyl group or glycidyloxy group is other than a hydroxyl group, a glycidyloxy group, or an alkoxy group. In this case, the group adjacent to the hydroxyl group or glycidyloxy group is more preferably a hydrogen atom, and it is more preferable that the at least one of the hydroxyl groups or glycidyloxy groups is a glycidyloxy group.

[0020] Also, as described above, at least one of R1 to R5 is a hydroxyl group or a glycidyloxy group, but it is preferable that one or two of R1 to R5 are a hydroxyl group or a glycidyloxy group, and more preferably one is a hydroxyl group or a glycidyloxy group. Further, it is preferable that at least one of R1 to R5 is a glycidyloxy group, more preferably one or two are glycidyloxy groups, and even more preferably one is a glycidyloxy group. Similarly, at least one of R6 to R 10 is a hydroxyl group or a glycidyloxy group, but it is preferable that one or two of R6 to R 10 are a hydroxyl group or a glycidyloxy group, and more preferably one is a hydroxyl group or a glycidyloxy group. Further, it is preferable that at least one of R6 to R 10 is a glycidyloxy group, more preferably one or two are glycidyloxy groups, and even more preferably one is a glycidyloxy group. Furthermore, when R 12 is a group represented by the formula (II), at least one of R 14 to R 18 is a hydroxyl group or a glycidyloxy group, but it is preferable that one or two of R 14 to R 18 are a hydroxyl group or a glycidyloxy group, and more preferably one is a hydroxyl group or a glycidyloxy group. Further, it is preferable that at least one of R 14 to R 18 is a glycidyloxy group, more preferably one or two are glycidyloxy groups, and even more preferably one is a glycidyloxy group.

[0021] Furthermore, it is preferable that one or two of R1 to R5 are a glycidyloxy group or a hydroxyl group, and the others are a hydrogen atom or a methoxy group, and one or two of R6 to R 10 are a glycidyloxy group or a hydroxyl group, and the others are a hydrogen atom or a methoxy group, and R 12If is the group shown by formula (II), then R 14 ~R 18 It is more preferable that one or two of them are glycidyloxy groups or hydroxyl groups, and the others are hydrogen atoms or methoxy groups. In this case, one of R1 to R5, R6 to R 10 one of the following, and R 14 ~R 18 It is more preferable that one of them is a glycidyloxy group or a hydroxyl group, and it is even more preferable that the glycidyloxy group or hydroxyl group is a glycidyloxy group.

[0022] In particular, from the viewpoint of being easily manufactured from biomass-derived raw materials, one embodiment is such that R3 and R8 are each independently a glycidyloxy group or a hydroxyl group, R2 and R7 are each independently a hydrogen atom, a methoxy group, or a glycidyloxy group or a hydroxyl group, R4 and R9 are each independently a hydrogen atom or a methoxy group, and R1, R5, R6, and R 10 It is more preferable that all of them are hydrogen atoms. And R 12 If is the group shown by formula (II), then R 16 is a glycidyloxy group or a hydroxyl group, R 15 is a hydrogen atom, a methoxy group, or a glycidyloxy group or a hydroxyl group, R 17 is a hydrogen atom or a methoxy group, R 14 , and R 18 It is more preferable that is a hydrogen atom. In this embodiment, the glycidyloxy group or hydroxyl group is preferably a glycidyloxy group. Furthermore, in this embodiment, it is even more preferable that both R4 and R9 are hydrogen atoms, and R 12 If is the group shown by formula (II), then R 17 It is even more preferable that it is a hydrogen atom.

[0023] Furthermore, from the viewpoint of being easily manufactured from biomass-derived raw materials, and from the viewpoint of minimizing the occurrence of side reactions during epoxy resin manufacturing and curing, in another embodiment, one of R1 to R5 is a glycidyloxy group or a hydroxyl group, and the rest are hydrogen atoms, and R6 to R10 It is more preferable that one of them is a glycidyloxy group or a hydroxyl group, and the rest are hydrogen atoms. 12 If is the group shown by formula (II), then R 14 ~R 18 It is more preferable that one of them is a glycidyloxy group or a hydroxyl group, and the rest are hydrogen atoms. In this other embodiment as well, it is preferable that the glycidyloxy group or hydroxyl group is a glycidyloxy group. Also, among these, R1~R 10 It is even more preferable that R3 and R8 are independently a glycidyloxy group or a hydroxyl group, and the remainder is a hydrogen atom, 12 If is the group shown by formula (II), then R 14 ~R 18 R 16 It is even more preferable that one of the groups is a glycidyloxy group or a hydroxyl group, and the remainder is a hydrogen atom. In this case as well, it is preferable that the glycidyloxy group or hydroxyl group is a glycidyloxy group.

[0024] In formula (I), m may be 1 or greater as described above, but in one embodiment, it is preferable that it be 2 or greater. When m is 2 or greater, trimerization or more occurs, increasing the number of epoxy groups that are spaced far apart from each other in the molecule, which increases the crosslinking density of the cured product and improves toughness and other properties. However, m may also be 1, in which case, for example, the heat resistance of the cured product tends to improve. It is presumed that when m is 1, the proportion of double bonds in a single molecule increases, thus improving heat resistance. Furthermore, while m may be 100 or less, it is preferable that it be 50 or less, more preferably 20 or less, and even more preferably 10 or less, from the viewpoint of ease of manufacture, handling, and heat resistance.

[0025] Furthermore, the epoxy resin shown in formula (I) may be a mixture of two or more types with different numbers of m. Therefore, the epoxy resin shown in formula (I) can also be characterized by the average value of m. The average value of m should be 1 or greater, but from the viewpoint of facilitating the formation of a crosslinked structure, it is better if it is greater than 1, and from that viewpoint, 1.1 or greater is preferred, 1.5 or greater is more preferred, and 1.8 or greater is even more preferred. Also, the average value of m should be 100 or less, but preferably 20 or less, more preferably 10 or less, even more preferably 5 or less, and even more preferably 4 or less.

[0026] R 12 It is preferable that R is a hydrogen atom. 12 When the group is represented by formula (II), n may be 1 or more as described above, but may also be 2 or more. When n is 2 or more, the number of epoxy groups that are far apart from each other can be increased, which increases the crosslinking density of the cured product and makes it easier to improve toughness and other properties. However, even if n is 1, it is preferable from the viewpoint of making it easier to improve properties such as the heat resistance of the cured product. Furthermore, n may be 100 or less, but from the viewpoint of ease of manufacture, handling, and heat resistance, it is preferably 50 or less, more preferably 20 or less, even more preferably 10 or less, and even more preferably 5 or less. Furthermore, the epoxy resin may be a mixture of two or more types with different numbers of n. In addition, the epoxy resin may be R 12 Compounds in which R is a hydrogen atom, 12 It may be a mixture of compounds in which is the group represented by formula (II). 12 Compounds in which n is a hydrogen atom can also be called compounds in which n is 0, and epoxy resins can be characterized by the average value of n, similar to m. The average value of n can be 0 or greater, or 0.5 or greater.

[0027] However, R 12 As described above, it is preferable that n is a hydrogen atom, and therefore, it is preferable that n is 0. 12The fact that the atom is a hydrogen atom prevents the molecular structure of the epoxy resin from becoming complex, resulting in good ease of manufacturing and handling. The average value of n can be 100 or less, but from the above viewpoint, it is better to make it smaller, preferably 10 or less, more preferably 5 or less, even more preferably 2 or less, and even more preferably 1 or less.

[0028] When R8 is a hydroxyl group or a glycidyloxy group, R7 may be the group shown in formula (I-3) above, in which case m is more preferably 1, and in formula (I-3), R 36 , R 37 , R 39 , R 40 It is even more preferable that all of them are hydrogen atoms. In that case, in formula (I), R 12 It is preferable that R3 is a hydrogen atom, and it is also preferable that R3 is a hydroxyl group or a glycidyloxy group.

[0029] The epoxy resin shown in formula (I) is obtained by glycidylating the hydroxyl groups of a hydroxystyrene polymer, as described later. It is preferable that all hydroxyl groups are glycidylated, and therefore, it is preferable that the epoxy resin does not contain hydroxyl groups. However, if the number of repeating units of n or m is large, it may be difficult for glycidylation to proceed completely. Therefore, the epoxy resin shown in formula (I) may contain hydroxyl groups, but even if it contains hydroxyl groups, it is preferable that the number of hydroxyl groups in one molecule be small. Specifically, in the epoxy resin shown in formula (I), the number of glycidyloxy groups should be 50% or more of the total number of hydroxyl groups and glycidyloxy groups, preferably 70-100%, more preferably 80-100%, even more preferably 90-100%, and most preferably 100%.

[0030] Furthermore, the epoxy resin shown in formula (I) has R3 and R8 as glycidyloxy groups, and R1, R2, R4~R7, and R9~R 13 It is particularly preferable that the atom is a hydrogen atom. In this case, the epoxy resin is as shown in the following formula (I-1). [ka] In formula (I-1), G is a glycidyl group, and m is the same as described above. Epoxy resins having the above structure can be easily synthesized from p-coumaric acid in high yield, and therefore can be efficiently synthesized from biomass. In formula (I-1) above, the value of m is as described above, and may be 1 or 2 or more. When m is 1, the heat resistance is further improved. Also, when m is 2 or more, the crosslinking density is improved, and toughness and other properties are improved. In formula (I-1) above, the epoxy resin exhibits a trans structure, but it may also have a cis structure or be a mixture of trans and cis structures.

[0031] Furthermore, in the present invention, an epoxy resin in another embodiment is R 12 This is the group represented by formula (II). Therefore, in another embodiment, the epoxy resin is preferably the compound represented by the following formula (I-2). [ka] In formula (I-2), G is a glycidyl group, and m and n are the same as above. The epoxy resin having the structure shown in formula (I-2) above can be synthesized from p-coumaric acid and can be efficiently synthesized from biomass. In this case, the value of m is as described above and may be 1 or greater than or equal to 2. Similarly, the value of n is as described above and may be 1 or greater than or equal to 2.

[0032] Furthermore, in yet another embodiment of the present invention, the epoxy resin may be such that R7 is the group represented by formula (I-3) described above. Therefore, in yet another embodiment, the epoxy resin may be the compound represented by the following formula (I-4). [ka] In formula (I-4), G represents a glycidyl group. The epoxy resin having the structure shown in formula (I-4) above can be synthesized from p-coumaric acid and can be efficiently synthesized from biomass.

[0033] In the epoxy resin, in the compound represented by formula (I-1), all of the OG groups may be glycidyloxy groups, but some of the OG groups may be hydroxyl groups, and the proportion of glycidyloxy groups in the compound represented by formula (I-1) is as described above. Similarly, in the compound represented by formula (I-2), all of the OG groups may be glycidyloxy groups as described above, but some of the OG groups may be hydroxyl groups, and the proportion of glycidyloxy groups in the compound represented by formula (I-2) is as described above. Similarly, in the compound represented by formula (I-4), all of the OG groups may be glycidyloxy groups as described above, but some of the OG groups may be hydroxyl groups, and the proportion of glycidyloxy groups in the compound represented by formula (I-4) is as described above. Furthermore, the epoxy resin of the present invention may be a mixture of the compound represented by formula (I-1) and the compound represented by formula (I-2). Furthermore, the epoxy resin of the present invention may be a mixture of the compound represented by formula (I-1) and the compound represented by formula (I-4). In this case, the compound represented by formula (I-1) preferably contains at least a compound in which m is 1, and preferably contains at least a compound in which m is 1 and a compound in which m is 2. Furthermore, the compound may be a mixture of the compound shown in formula (I-1), the compound shown in formula (I-2), and the compound shown in formula (I-4).

[0034] <Method for manufacturing epoxy resin> The present invention provides a method for producing epoxy resin, which involves heating a compound represented by formula (III) in the presence of a basic substance to obtain a hydroxystyrene polymer, and then reacting the obtained hydroxystyrene polymer with an epihalohydrin to obtain an epoxy resin. The resulting epoxy resin is preferably the epoxy resin represented by formula (I) above, but epoxy resins other than the epoxy resin represented by formula (I) above may also be produced. The epoxy resin obtained by the manufacturing method of the present invention has good heat resistance because it contains a double bond in the linking group connecting the aromatic rings. Furthermore, by using the compound shown in formula (III) as a raw material, it can be easily manufactured using biomass-derived compounds as starting materials. [ka] In formula (III), R 21 ~R 25 Each of these is an organic group having 1 to 20 carbon atoms, which may independently contain a hydrogen atom, a halogen atom, a hydroxyl group, or a heteroatom, and R 21 ~R 25 At least one of them is a hydroxyl group. In formula (III), the double bond connecting the carboxyl group and the benzene ring structure is trans; however, compounds shown in formula (III) may isomerize upon light irradiation, and there may also be compounds where the double bond connecting the carboxyl group and the benzene ring structure is cis.

[0035] R 21 ~R 25 Halogen atoms in include fluorine, chlorine, bromine, and iodine. 21 ~R 25 The C1-C20 organic group which may have a heteroatom is a hydrocarbon group which may have a heteroatom. The hydrocarbon group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group which has an aromatic ring. The aliphatic hydrocarbon group may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group. Examples of heteroatoms include nitrogen atoms, sulfur atoms, oxygen atoms, halogen atoms, and phosphorus atoms. While heteroatoms are not particularly limited, examples include oxygen atoms that constitute ether bonds, ester bonds, keto groups, alkoxy groups, and nitro groups; sulfur atoms that constitute sulfonyl groups and thiol bonds; nitrogen atoms that constitute nitro groups and cyano groups; and halogen atoms that substitute for hydrogen atoms in hydrocarbon groups. Heteroatoms may be located in the middle of a hydrocarbon chain or at its terminus. The number of carbon atoms in the above organic group is preferably 1 to 10, more preferably 1 to 6, even more preferably 1 to 3, and most preferably 1. Preferred specific examples of the organic group are alkoxy groups or hydrocarbon groups.

[0036] Among those mentioned above, R 21 ~R 25 Each of these is preferably independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group, or a hydrocarbon group. Furthermore, an alkyl group is preferred as the hydrocarbon group. Details of the alkoxy group and alkyl group are as described in formula (I). Furthermore, R 21 ~R 25 It is more preferable that each of these is independently a hydrogen atom, a hydroxyl group, a methoxy group, or a methyl group.

[0037] Furthermore, R 21 ~R 25 Preferably, at least one of the groups is a hydroxyl group, and the groups adjacent to the hydroxyl group are other than hydroxyl and alkoxy groups. In this way, by ensuring that the hydroxyl group is not adjacent to hydroxyl and alkoxy groups within a single aromatic ring, intramolecular side reactions within the same aromatic ring can be suppressed during synthesis and other processes.

[0038] R 21 ~R 25 At least one of them is a hydroxyl group, R 21 ~R 25 Preferably, one or two of them are hydroxyl groups, R 21 ~R 25It is more preferable that one of them is a hydroxyl group. Furthermore, R 21 ~R 25 It is also preferable that one or two of the components are hydroxyl groups, and the others are hydrogen atoms or methoxy groups. In particular, from the viewpoint of being easily obtainable from biomass-derived raw materials, one embodiment is R 23 is a hydroxyl group, R 22 is a hydrogen atom, a methoxy group, or a hydroxyl group, and R 24 is a hydrogen atom or a methoxy group, R 21 and R 25 Preferably, all of them are hydrogen atoms. In this embodiment, R 24 It is even more preferable that it be a hydrogen atom. Furthermore, from the viewpoint of being easily obtainable from biomass-derived raw materials and minimizing the occurrence of side reactions during epoxy resin production and curing of the obtained epoxy resin, as another embodiment, R 21 ~R 25 It is also preferable that one of them is a hydroxyl group and the rest are hydrogen atoms, and in particular, R 23 Preferably, one of the atoms is a hydroxyl group, and the remainder is a hydrogen atom.

[0039] Specific examples of the compound represented by formula (III) include o-coumaric acid, m-coumaric acid, p-coumaric acid, ferulic acid, sinapic acid, caffeic acid, isoferulic acid, umberic acid, 3,4,5-trihydroxycinnamic acid, and 2,4,5-trihydroxycinnamic acid. Among these, p-coumaric acid, ferulic acid, or caffeic acid are preferred, with p-coumaric acid being particularly preferred. These compounds, especially p-coumaric acid, ferulic acid, or caffeic acid, are preferred because biomass-derived compounds are readily available. The compound represented by formula (III) may be used alone or in combination of two or more.

[0040] (Synthesis of hydroxystyrene polymers) In this manufacturing method, a compound represented by formula (III) as described above is heated in the presence of a basic substance to obtain a hydroxystyrene polymer. Here, the basic substance used is preferably used as a catalyst to decarboxylate and polymerize the compound represented by formula (III). From the viewpoint of ensuring that decarboxylation and polymerization proceed appropriately, the basic substance is preferably a non-amine basic substance. Specifically, the basic substance is preferably at least one of an alkali metal or alkaline earth metal hydroxide, carbonate, or bicarbonate.

[0041] More specifically, examples include alkali metal hydroxides such as potassium hydroxide, sodium hydroxide, lithium hydroxide, and cesium hydroxide; alkaline earth metal hydroxides such as magnesium hydroxide, calcium hydroxide, and barium hydroxide; alkali metal carbonates such as potassium carbonate, sodium carbonate, and lithium carbonate; alkaline earth metal carbonates such as magnesium carbonate, calcium carbonate, and barium carbonate; alkali metal bicarbonates such as potassium bicarbonate, sodium bicarbonate, and lithium bicarbonate; and alkaline earth metal bicarbonates such as magnesium bicarbonate, calcium bicarbonate, and barium bicarbonate. These basic substances may be used individually or in combination of two or more. Among the above, alkali metal hydroxides are preferred, and from the standpoint of economy and availability, it is preferable to use at least one of sodium hydroxide and potassium hydroxide.

[0042] The amount of basic catalyst added is not particularly limited, but is preferably 0.01 to 5 moles, more preferably 0.1 to 4 moles, and even more preferably 0.2 to 2 moles per mole of the compound shown in formula (III). In this manufacturing method, the number of repeating units (n and m in formulas (I) and (II)) can be adjusted as appropriate by changing the type and amount of basic substance added.

[0043] In this manufacturing method, the compound represented by formula (III) is heated in a solvent in the presence of a basic substance to obtain a hydroxystyrene polymer. Here, the solvent is preferably a mixed solvent of water and a specific organic solvent represented by the following formula (IV) (hereinafter also referred to as the specific solvent). [ka] In formula (IV), R 26 This is an organic group having 1 to 10 carbon atoms, which may contain heteroatoms. By using the above-mentioned mixed solvent in this manufacturing method, decarboxylation and polymerization proceed appropriately, and the yield of the resulting hydroxystyrene polymer can be easily improved.

[0044] In formula (IV) above, the C1-C10 organic group which may have a heteroatom is a hydrocarbon group which may have a heteroatom. The hydrocarbon group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group having an aromatic ring. The aliphatic hydrocarbon group may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group. Examples of heteroatoms include nitrogen atoms, sulfur atoms, oxygen atoms, halogen atoms, and phosphorus atoms. While not particularly limited, examples of heteroatoms include oxygen atoms constituting ether bonds, ester bonds, keto groups, alkoxy groups, and nitro groups; sulfur atoms constituting sulfonyl groups and thiol bonds; nitrogen atoms constituting nitro groups and cyano groups; and halogen atoms substituted for hydrogen atoms in hydrocarbon groups. Heteroatoms may be located in the middle or at the end of a hydrocarbon chain. Furthermore, the heteroatom is preferably an oxygen atom, and more preferably an oxygen atom constituting an ether bond or an alkoxy group. The number of carbon atoms in the above organic group is preferably 2 to 8, more preferably 3 to 6.

[0045] In equation (IV), R 26 It is preferable that the structure is represented by the following formula (V). [ka] In formula (V), R 27 R is an alkyl group having 1 to 4 carbon atoms. 28 * indicates a hydrogen atom or a methyl group, and * indicates the bond position to the hydroxyl group in formula (IV).

[0046] R 27 Examples of alkyl groups in include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl groups. In addition, in formula (V), R 27 is a methyl group or an ethyl group, and R 28 It is more preferable that the group is a methyl group. In this manufacturing method, if the specific solvent has the structure shown in formula (V) above, decarboxylation and polymerization proceed more appropriately, and the yield of the resulting hydroxystyrene polymer can be more easily improved. From the viewpoint of minimizing the formation of by-products during the reaction, secondary alcohols are preferred as the specific solvent. Furthermore, from the viewpoint of reaction rate, solvents with a boiling point of around 100 to 130°C are preferred, as are those with good miscibility with water.

[0047] Specific examples of specific solvents include 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 3-ethoxy-1-propanol, 3-methoxy-1-propanol, 1-methoxy-2-methyl-2-propanol, 1-(2-methoxy-2-methylethoxy)-2-propanol, 1-propoxy-2-propanol, 1-isopropoxy-2-propanol, and 1-butoxy-2-propanol. 26 The compound may be anything other than a compound having the structure shown in formula (V), such as 2-butanol, 2-pentanol, or isopropanol. Among the above, 1-methoxy-2-propanol and 1-ethoxy-2-propanol are preferred, and 1-methoxy-2-propanol is more preferred.

[0048] In this mixed solvent, the mixing ratio of water to the specific solvent is not particularly limited, but the volume ratio of the specific solvent to water (specific solvent / water) is preferably 1 / 9 to 9 / 1, more preferably 3 / 7 to 7 / 3, and even more preferably 4 / 6 to 6 / 4. The volume ratio is preferably calculated using the volumes of water and the specific solvent at 25°C. The reaction is carried out by adding the above-mentioned basic substance and the compound shown in formula (III) to the solvent. The solvent should be adjusted so that the concentration of the compound shown in formula (III) is, for example, about 10 to 500 g / L, preferably about 50 to 300 g / L.

[0049] In this manufacturing method, the compound represented by formula (III) is reacted by heating it in the mixed solvent described above, preferably in the presence of a basic substance. The reaction is preferably carried out at a temperature of 50°C or higher, preferably 70°C or higher, and more preferably 90°C or higher, but it is even more preferable to carry it out under reflux conditions. Therefore, the heating temperature may be, for example, 120°C or lower. The reaction is preferably carried out at the above heating temperature for 30 minutes to 24 hours, preferably 2 to 12 hours. In this manufacturing method, increasing the reaction time makes it easier to increase the number of repeating units (m, n).

[0050] Through the above reaction, the compound shown in formula (III) is decarboxylated and polymerized to obtain a hydroxystyrene polymer. The obtained hydroxystyrene polymer is preferably the compound shown in formula (I) before glycidylation. Therefore, the hydroxystyrene polymer is preferably a compound in which the glycidyloxy group in the structure shown in formula (I) is a hydroxyl group. That is, at least one of R1 to R5 and R6 to R 10 At least one of them is independently a hydroxyl group, and R 12 If is the group shown by formula (II), then R 14 ~R 18 Aside from being a compound in which at least one of the groups is a hydroxyl group, it may have the structure shown in formula (I) described above, and the preferred embodiment is also as described above, except that the glycidyloxy group is a hydroxyl group.

[0051] The obtained hydroxystyrene polymer may be separated and purified as needed, and then reacted with the epihalohydrin described later. Separation and purification of the hydroxystyrene polymer can be carried out by general unit operations such as solvent removal, separation of the hydroxystyrene polymer by extraction using water and a hydrophobic solvent, solvent removal, and distillation, or by combining these as appropriate. Among these, it is preferable that the obtained hydroxystyrene polymer be separated from the solvent by solvent removal, extraction, etc., before being reacted with the epihalohydrin.

[0052] (Glycidylation) In this manufacturing method, epoxy resin can be obtained by reacting the resulting hydroxystyrene polymer with an epihalohydrin. The reaction between the hydroxystyrene polymer and the epihalohydrin is preferably carried out in the presence of a catalyst. Examples of catalysts include quaternary ammonium salts such as benzyltriethylammonium chloride, benzyltriethylammonium bromide, tetrabutylammonium fluoride, and tetrabutylammonium bromide. The catalyst may be used alone or in combination of two or more. The amount of catalyst added is preferably 0.001 to 0.5 equivalents, more preferably 0.01 to 0.4 equivalents, and even more preferably 0.03 to 0.3 equivalents, based on the structural units derived from the compound shown in formula (III) in the hydroxystyrene polymer.

[0053] Examples of epihalohydrins that can be used in glycidylation include epifluorohydrin, epichlorohydrin, epibromohydrin, and epiiodohydrin, among which epichlorohydrin is preferred in terms of reactivity and cost-effectiveness.

[0054] The above reaction may be carried out in the presence of a solvent, or it may be carried out without a solvent. By using an excess amount, especially a large excess, of epihalohydrin relative to the hydroxystyrene polymer, the hydroxystyrene polymer is appropriately diluted by the epihalohydrin, and the reaction can proceed appropriately even without a solvent or with only a small amount of solvent. Specifically, the amount of epihalohydrin is preferably more than 1 equivalent, more preferably 2 equivalents or more, more preferably 5 equivalents or more, and even more preferably 8 equivalents or more, based on the hydroxyl groups in the hydroxystyrene polymer. Furthermore, in order to facilitate the removal of unreacted epihalohydrins after the reaction and to improve production efficiency, the amount of epihalohydrin used is preferably 50 equivalents or less, more preferably 40 equivalents or less, and even more preferably 30 equivalents or less, based on the hydroxyl groups in the hydroxystyrene polymer. In addition, aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, halogenated solvents, ester solvents, and ether solvents can be used as reaction solvents. The reaction in the presence of the catalyst is carried out, for example, at 40 to 150°C, preferably 60 to 120°C, for 30 minutes to 24 hours, preferably 2 to 12 hours.

[0055] In this manufacturing method, the epoxy resin obtained by the above reaction may be separated and purified as appropriate. Separation or purification of the epoxy resin can be carried out by general unit operations such as distillation of epihalohydrin, distillation of reaction solvent used as needed, separation of the target epoxy resin and water-soluble compound by extraction using water and a hydrophobic solvent, distillation of the extraction solvent, distillation, or a combination of these as appropriate. The separated epihalohydrin may be reused in the glycidylation reaction described above.

[0056] The epoxy resin shown in formula (I) and the epoxy resin produced by the above manufacturing method can be produced from biomass for at least a portion of the raw materials, and an epoxy resin with a high bio-content can be obtained. Specifically, the compound shown in formula (III) can be obtained from biomass-derived compounds such as L-tyrosine by microbial synthesis. Therefore, the epoxy resin shown in formula (I) and the epoxy resin produced by the above manufacturing method can be derived from biomass, particularly from compounds synthesized by microorganisms. Furthermore, the method of obtaining p-coumaric acid by microbial synthesis is stereoselective, allows for the acquisition of paracoumaric acid in high yield, and subsequent polymerization and glycidylation are relatively simple. Therefore, the epoxy resin represented by formula (I) of the present invention can be easily manufactured, even though it is a compound that can be obtained from biomass. Furthermore, in the above manufacturing method, typically, among the compounds shown in formula (I), R 12 Compounds in which R is a hydrogen atom are produced, 12 In addition to compounds in which R is a hydrogen atom, 12 Compounds in which the group is represented by formula (II) may also be produced.

[0057] <Cured body> The cured product of the present invention (hereinafter also referred to as the "epoxy cured product") is obtained by curing an epoxy resin. The epoxy resin may be the epoxy resin shown in formula (I) above, or an epoxy resin produced by the manufacturing method described above. In the following description, these will be collectively referred to as the "epoxy resin of the present invention." Epoxy cured bodies are generally cured by a curing agent, and therefore, they are preferably cured bodies of a curable composition containing an epoxy resin and a curing agent. That is, one embodiment of the present invention also provides 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 is capable of curing 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 which are condensates of dimer or trimer acids and polyamines, Lewis acids such as boron trifluoride-amine complexes, phenols or their derivatives, etc. Mercapto-based curing agents can also be used.

[0058] Amine-based curing agents include polyamines such as aliphatic polyamines and aromatic polyamines. Examples of aliphatic polyamines include ethylenediamine, diethylenetriamine, triethylenetetramine, dipropylenetriamine, tetraethylenepentamine, dimethylaminopropylamine, bishexamitylentriamine, cyclohexylaminopropylamine, aminoethylethanolamine, monohydroxyethyldiethylenetriamine, bishydroxyethyldiethylenetriamine, N-(2-hydroxypropyl)ethylenediamine, hexamethylenediamine, diethylene glycol bis(3-aminopropyl) ether, diethylaminopropylamine, 3,9-bis(3-aminopropyl)-2,4,8,10-tetrasuoxaspiro[5,5]undecane, menthanediamine, isophoronediamine, 4,4'-methylenebis(cyclohexylamine), bis(4-amino-3-methylcyclohexyl)methane, and N-aminoethylpiperazine. Aromatic polyamines are amines having an aromatic ring, and specifically include phenylenediamine, diaminodiphenylmethane, diaminoanisole, toluenediamine, various xylylenediamines such as metaxylylenediamine, and diaminodiphenylsulfone.

[0059] In addition, amine-based curing agents, imidazole-based curing agents, amidoamine-based curing agents, etc., may also be used. Examples of imidazole-based curing agents include 2-methylimidazole, 2-ethylimidazole, 2-undecylimidazole, 2,4-dimethylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 1,2-diethylimidazole, 2-phenyl-4-methylimidazole, 2,4,5-triphenylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, and 1-benzyl-2-phenylimidazole. Examples include zyl-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, and 2-phenyl-4-methyl-5-hydroxymethylimidazole. Examples of amidoamine-based curing agents include dicyandiamide.

[0060] Examples of acid anhydride-based curing agents include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, chloridenic anhydride, dodecinyl succinic anhydride, methyltetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, and methylhexahydrophthalic anhydride, represented by 4-methylhexahydrophthalic anhydride. Examples of phenol derivatives include bisphenols such as bisphenol F and bisphenol A and their derivatives, trifunctional phenols such as tri(hydroxyphenyl)methane and tri(hydroxyphenyl)ethane and their derivatives, and compounds obtained by reacting phenols such as phenol novolac with formaldehyde. As mercapto-based curing agents, compounds having two mercapto groups in the molecule, such as 1,4-bis(3-mercaptobutyryloxy)butane, and compounds having three or more mercapto groups, such as pentaerythritol tetrakis(3-mercaptobutyrate), can also be used. The hardening agent may be used alone or in combination of two or more types.

[0061] As a curing agent, amine-based curing agents are preferred among those mentioned above, and polyamines are preferred among them. Polyamines preferably have a total of two or more primary and secondary amino groups in one molecule, and preferably have at least one primary amino group, and more preferably have two or more primary amino groups. The total number of primary and secondary amino groups in one molecule of polyamines is not particularly limited, but is for example 8 or less, preferably 5 or less, and more preferably 3 or less.

[0062] The amount of curing agent to be added is, for example, 1 to 100 parts by mass, preferably 2 to 50 parts by mass, per 100 parts by mass of epoxy resin. If the amount is above this lower limit, proper curing can be achieved, and if a three-dimensional network structure is formed, for example, the structure will be strong, and the mechanical and thermal properties will tend to be good. If the amount is below this upper limit, it is possible to prevent the amount of curing agent from being excessively large, and the mechanical and thermal properties will tend to be good. The amount of curing agent to be added should be appropriately adjusted according to the epoxy equivalent of the epoxy resin, and, if an amine-based curing agent is used, according to the amount of active hydrogen of the amine-based curing agent (i.e., the hydrogen atoms bonded to the nitrogen atom in the amino group). For example, it is good to adjust it so that the ratio of the number of active hydrogens to the number of epoxy groups is 1 or approximately 1, specifically 0.5 to 2, preferably 0.75 to 1.5, and more preferably 0.9 to 1.1.

[0063] The glass transition temperature (Tg) of the epoxy cured material, as measured by differential scanning calorimeter, is, for example, 120°C, preferably 140°C or higher, more preferably 145°C or higher, and even more preferably 148°C or higher. By increasing the glass transition temperature of the epoxy cured material, the thermal performance can be improved, resulting in good heat resistance. Furthermore, the glass transition temperature (Tg) of the epoxy cured material is not particularly limited, but may be, for example, 300°C or lower, or 200°C or lower.

[0064] The epoxy cured body is not particularly limited, but can be produced by mixing an epoxy resin and a curing agent to obtain a curable composition, and then heating it as needed. The heating temperature is not particularly limited, but for example, it can be room temperature (23°C) to 300°C, preferably 40°C to 250°C, and heating within this temperature range may be for, for example, 10 minutes to 13 hours, preferably 1 to 6 hours. The heating temperature may be gradually increased as curing progresses. The curable composition containing the epoxy resin and curing agent may be diluted by adding a solvent, and may contain other components as appropriate. If diluted with a solvent, the solvent may be removed by drying it as appropriate through the heating process.

[0065] The curable composition may contain a curing accelerator in addition to the epoxy resin and curing agent of the present invention. The curing accelerator is a component that promotes curing by the curing agent. For example, since dicyandiamide and the like have a high curing temperature when used alone, a curing accelerator can be used to enhance the curing activity of dicyandiamide and the like. Examples of curing accelerators for dicyandiamide include urea-based, imidazole-based, tertiary amine-based, and caprolactam. Among these, urea-based and imidazole-based are preferred, and 2,4-diamino-6-(2-methylimidazolyl-(1))-ethyl-s-triazine, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, and 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 per 100 parts by mass of epoxy resin.

[0066] The epoxy resin and epoxy cured product of the present invention can be used in a variety of fields, and are not particularly limited, but can be used in any field, such as the electrical, transportation, civil engineering, construction, mechanical, and medical fields. The epoxy resin and epoxy cured product of the present invention can be used in various forms, such as various molded articles, adhesives, paints, fillers, films, powders, composites, and foams. More specifically, it can be used in a variety of applications, including adhesives for dissimilar materials, rubber-resin adhesives, wellbond applications, bonding substrates to semiconductor elements such as die attach, bonding films for flexible substrates, various adhesives for construction and civil engineering applications, various coating applications such as anti-fogging paints, electrodeposition coatings, corrosion-resistant paints, floor coatings, and other coatings for construction and civil engineering applications, sealing materials such as for insulated wires, fiber scrubbers, fiber reinforcement materials such as for prepregs, electrical insulating materials and protective materials for electronic components, photosensitive resins, lens applications, dental materials, and more, but is not limited to these applications.

[0067] The epoxy resin-containing composition containing the epoxy resin of the present invention can be blended with various components depending on the application. In addition to the curing agent and curing accelerator mentioned above, such components include resins other than the epoxy resin of the present invention, latex, fillers, pigments, silane coupling agents, surfactants, ultraviolet absorbers, antioxidants, stabilizers, plasticizers, leveling agents, defoamers, antistatic agents, flame retardants, lubricants, and dispersants.

[0068] The following describes in more detail compositions containing the epoxy resin of the present invention (hereinafter also referred to as "epoxy resin-containing compositions") used for each application, and compositions having components derived from the epoxy resin of the present invention. However, each of the following compositions may, if necessary, contain components other than those specifically described below. The epoxy resin-containing composition may be a curable composition containing a curing agent in addition to the epoxy resin, but depending on the application, it may be a composition that does not contain a curing agent.

[0069] (For adhesive use) For example, when used as an adhesive, the epoxy resin-containing composition may contain epoxy resin and a curing agent, but in addition to these, it may also contain polymer fine particles as a filler component, from the viewpoint of improving the adhesive strength and imparting impact properties to the adhesive. When polymer fine particles are included, the adhesive is preferably used for dissimilar material adhesive applications in fields such as automobiles, or for well-bond applications. Examples of dissimilar materials in dissimilar adhesive applications include combinations of two materials selected from various materials such as various steel materials, aluminum, aluminum alloys, fiber-reinforced plastic (FRP) sheets such as carbon fiber and glass fiber, and carbon fiber reinforced plastic (CFRP). Furthermore, the epoxy resin-containing composition used in the above adhesive applications may contain epoxy resins other than the epoxy resin of the present invention in addition to the epoxy resin of the present invention.

[0070] The polymer microparticles are preferably polymer microparticles having a core-shell structure. Polymer microparticles having a core-shell structure refer to polymer particles in which the molecular structure differs between the central part (core) and the outer part (shell). Examples of components constituting the core portion of polymer microparticles having a core-shell structure include butadiene rubber (BR), acrylic rubber (ACM), silicone rubber (Si), butyl rubber (IIR), nitrile rubber (NBR), styrene-butadiene rubber (SBR), isoprene rubber (IR), and ethylene propylene rubber (EPR). Among these, butadiene rubber is preferred. The components constituting the shell portion of polymer microparticles having a core-shell structure are graft polymerized onto the core portion and are preferably covalently bonded to the polymer constituting the core component. Examples of components constituting the shell portion include acrylic acid ester monomers, methacrylic acid ester monomers, and aromatic vinyl monomers. The polymer fine particles are contained in the epoxy resin-containing composition in an amount of, for example, 1 to 100 parts by mass, preferably 2 to 80 parts by mass, and more preferably 4 to 60 parts by mass, per 100 parts by mass of epoxy resin contained in the epoxy resin-containing composition. The polymer fine particles having a core-shell structure may be used alone or in combination of two or more types.

[0071] In the above-mentioned adhesives for dissimilar material bonding or wellbond applications, the epoxy resin-containing composition may use any of the curing agents listed above as appropriate, but it is preferable to include dicyandiamide. The curing agent content is preferably 0.01 to 30 parts by mass, more preferably 0.1 to 25 parts by mass, and even more preferably 1 to 20 parts by mass, per 100 parts by mass of epoxy resin. Furthermore, when the above adhesive is used for Wellbond, the epoxy resin-containing composition preferably contains blocked urethane. Blocked urethane refers to an elastomer type compound containing urethane groups and / or urea groups, and having isocyanate groups at its terminals, wherein all or part of the terminal isocyanate groups are capped with various blocking agents having active hydrogen groups. Compounds in which all of the terminal isocyanate groups are capped with blocking agents are particularly preferred. Specific examples of blocked urethane include the compounds described in International Publication No. 2016 / 163491. The amount of blocked urethane in the epoxy resin-containing composition is preferably 1 to 50 parts by mass, more preferably 2 to 40 parts by mass, and even more preferably 5 to 30 parts by mass, per 100 parts by mass of epoxy resin.

[0072] Furthermore, the epoxy resin-containing composition may be used as a rubber-resin adhesive in tires and the like. An example of a rubber-resin adhesive is a curable composition containing synthetic rubber latex in addition to the epoxy resin of the present invention. The synthetic rubber latex is not particularly limited, but examples include those containing an unsaturated diene, such as styrene-butadiene copolymer rubber latex, vinylpyridine-styrene-butadiene copolymer rubber latex, carboxyl group-modified styrene-butadiene copolymer rubber latex, nitrile rubber latex, and chloroprene rubber latex. These may be used individually or in combination of two or more. In an epoxy resin-containing composition used as a 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 to 75% by mass, and more preferably 55 to 75% by mass, based on solid content.

[0073] Furthermore, it is preferable that the curable composition containing synthetic rubber latex further contains a water-soluble carbodiimide. A water-soluble carbodiimide means a carbodiimide that is soluble in water, and includes carbodiimides that are aqueous and partially water-soluble. The water-soluble carbodiimide is a compound having a carbodiimide (chemical formula: -N=C=N-) and a hydrophilic segment in its molecule. The water-soluble carbodiimide can be used as a dehydration condensation agent capable of forming ester or amide bonds between the COOH group and the OH group or amino group of a compound contained in an aqueous solution. For example, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (WSC) is known to activate a carboxyl group, and its active intermediate reacts with an amino group and a hydroxyl group to form an amide and an ester.

[0074] It is presumed that water-soluble carbodiimide can crosslink and coat the surface of synthetic rubber latex having an unsaturated diene, and that when compounded with the epoxy resin of the present invention, it can bond the resin of the adherend to the rubber. The water-soluble carbodiimide is preferably a water-soluble salt such as a hydrochloride or sulfate. More specifically, examples of water-soluble carbodiimides include 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC); water-soluble salts of 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide such as 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide-metho-p-toluenesulfate; triazine-based condensing agents such as 4-(4,6-dimethoxy-1,3,5-triazine-2-yl)-4-methylmorpholinium chloride (DMT-MM); and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) is preferably used. In a 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, more preferably 0.3 to 10% by mass, even more preferably 0.5 to 7% by mass, and still more preferably 0.5 to 5% by mass, based on solid content.

[0075] Furthermore, the epoxy resin of the present invention used in rubber-resin adhesives only needs to have two or more epoxy groups per molecule, but preferably it contains four or more epoxy groups per molecule. In an epoxy resin-containing composition for rubber-resin adhesives, the epoxy resin content is not particularly limited, but is preferably 0.1 to 40% by mass, more preferably 0.4 to 40% by mass, and particularly preferably 1.0 to 30% by mass, based on solid content. The epoxy resin-containing composition for rubber-resin adhesives is not particularly limited, but it is preferable that each component be dispersed or dissolved in water and used as a dispersion.

[0076] In adhesive applications, it may be used in electronic equipment applications, for example, in applications where it is used to bond a substrate to a semiconductor element. More specifically, it may be used in die-attach applications, and may also be used as a silver paste material by incorporating silver particles, for example. When used as a silver paste material, the epoxy resin-containing composition may contain silver particles, the epoxy resin of the present invention, and a curing agent, and the composition may be used diluted with a solvent. The epoxy resin-containing composition may also contain epoxy resins other than the epoxy resin of the present invention. Furthermore, phenol derivatives and dicyandiamides are preferred as curing agents, and these may be used in combination. In the epoxy resin-containing composition, the silver particle content is, for example, 70 to 98% by mass, preferably 75 to 95% by mass, based on solid content. The epoxy resin content is, for example, 1 to 20% by mass, preferably 2 to 15% by mass, based on solid content. The curing agent content is, for example, 0.1 to 1.5% by mass, preferably 0.2 to 1.0% by mass.

[0077] When used as an adhesive, it may be used for flexible substrates. As an adhesive for flexible substrates, for example, it may be used to bond copper foil to the polyimide film that makes up the substrate, and may be used 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. It may also contain epoxy resins other than the epoxy resin of the present invention, or resins other than epoxy resins. Examples of such resins include polyester polymers such as polyester polyurethane resin. 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 polyester polyol as raw materials. In addition to the polyester polyurethane resin, it may also contain a resin having a carboxyl group or a carboxylic acid anhydride structure. Furthermore, while the above-mentioned curing agents may be used as appropriate, imidazole derivatives such as imidazole silane compounds may also be used in addition to those mentioned above. Furthermore, the epoxy resin-containing compositions for flexible substrates described above may also contain organic fillers, metal fillers, inorganic fillers other than metal fillers, and the like. In the epoxy resin-containing composition used for the flexible substrate described above, the epoxy resin content is preferably 1 to 60% by mass, more preferably 2 to 40% by mass, and even more preferably 3 to 20% by mass, based on the total amount of components other than the filler mentioned above.

[0078] (Paint application) The epoxy resin of the present invention may be used in paint applications or as a binder resin for paints. Specifically, for example, when used as an anti-fogging paint, it may be used in a paint composition containing the epoxy resin of the present invention and silica particles. This paint composition may optionally contain a silane coupling agent or the like. When used as an anti-fogging paint, it is preferable that the paint composition be used as a dispersion by dispersing or dissolving each component in a liquid medium such as water. Furthermore, the binder resin may include epoxy resins other than the epoxy resin of the present invention or resins other than epoxy resins. As silica particles, water-dispersible silica is preferred, and colloidal silica is also preferred. As liquid media, water and organic solvents are examples, with water or a mixed solvent of water and an organic solvent being preferred. In the case of a mixed solvent, the organic solvent can be any solvent that can disperse silica, for example, ethylene glycol monobutyl ether is preferred. In the above coating composition, the epoxy resin content may be 0.1 to 1000 parts by mass, 0.5 to 500 parts by mass, or 1 to 100 parts by mass per 100 parts by mass of silica particles.

[0079] (For electrodeposition coating) For example, when used in electrodeposition coating applications, epoxy resin may be reacted with an amine to form an aminerated 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. The above primary amines can be controlled by forming a ketimine group using a ketone compound, which is known as blocking. Tertiary amines may also be used as amines, and specific examples include triethylamine, N,N-dimethylbenzylamine, and N,N-dimethylethanolamine. The coating composition for electrodeposition coating may, for example, contain an amineralized epoxy resin and a curing agent such as a blocked polyisocyanate curing agent, and may also optionally contain a pigment dispersion paste. The pigment dispersion paste contains a pigment dispersion resin and a pigment. The coating composition for electrodeposition coating may be used as an emulsion or the like.

[0080] (Anti-corrosion paint) In paint applications, the paint composition may be a curing composition containing the epoxy resin of the present invention and a curing agent. Such a paint composition may contain epoxy resins other than the epoxy resin of the present invention, and may also contain pigments and pigment dispersants, and may contain silane coupling agents to improve adhesion. It may also be used after being diluted with an organic solvent. A paint composition containing epoxy resin and a curing agent is preferably used, for example, in a corrosion-resistant paint composition, and is particularly preferably used for corrosion protection of ships. In the paint composition, the epoxy resin content is preferably 1 to 60% by mass, more preferably 5 to 50% by mass, based on solid content.

[0081] (Floor coating agent) The epoxy resin of the present invention may be used in building and civil engineering applications, for example, as a floor coating agent. When used as a floor coating agent, the epoxy resin-containing composition may contain the epoxy resin of the present invention and a curing agent, but it is preferable to further contain an inorganic filler. As the inorganic filler, known inorganic fillers used in floor coating 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 an epoxy resin-containing composition for floor coatings, the inorganic filler content is, for example, about 1 to 1,000 parts by mass, preferably 10 to 200 parts by mass, and more preferably 20 to 100 parts by mass, per 100 parts by mass of epoxy resin. Of course, epoxy resin-containing compositions may be used in building and civil engineering applications other than as floor coatings, and may be used as tank paints, pipe interior paints, exterior paints, etc. They may also be used as adhesives in building and civil engineering applications, for example, to bond various structures.

[0082] (For encapsulant use) When the epoxy resin of the present invention is used for sealing applications, preferably for sealing coated wires, it may be used as a curable composition containing, for example, an epoxy resin and a curing agent. While any of the above-mentioned curing agents can be used as the curing agent in sealing applications, amine-based curing agents and mercapto-based curing agents are preferred. Furthermore, the curable composition used in sealing applications preferably contains a silane coupling agent.

[0083] (Fiber scrubber) When the epoxy resin of the present invention is used as a fiber sizing agent, it is preferable to use it in combination with a polyester resin having a sulfonic acid base. As the polyester resin having a sulfonic acid base, aromatic polyester resins and aliphatic polyester resins can be used, but it is preferable to use an aromatic polyester resin. As the aromatic polyester resin, it is preferable to have structural units derived from aromatic dicarboxylic acids such as isophthalic acid and terephthalic acid. Furthermore, the epoxy resin-containing composition for fiber sizing agents preferably contains a surfactant in addition to the epoxy resin and the polyester resin having a sulfonic acid base as described above, and an aromatic nonionic surfactant is preferred as the surfactant. Examples of aromatic nonionic surfactants include polyoxyalkylene alkylphenyl ethers, polyoxyalkylene styrene phenyl ethers, polyoxyalkylene benzylphenyl ethers, polyoxyalkylene cumylphenyl ethers, polyoxyalkylene naphthylphenyl ethers, and polyoxyalkylene styrene (alkylphenyl ethers), and among these, polyoxyalkylene styrene phenyl ethers such as polyoxyethylene styrene phenyl ether are preferred. The epoxy resin-containing composition for fiber sizing agents may also contain epoxy resins other than the epoxy resin of the present invention. The epoxy resin-containing composition for fiber sizing agents is preferably used as an aqueous composition, and is preferably used as an aqueous dispersant, for example. In an epoxy resin-containing composition for fiber sizing agents, the epoxy resin content is, for example, 75 to 95% by mass on a solid content basis, but preferably 80 to 95% by mass.

[0084] (For prepreg use) The epoxy resin of the present invention may be used in prepreg applications, and is particularly suitable for use as a matrix resin impregnated into fibrous materials such as reinforcing fibers used in prepreg applications. When used as a matrix resin, the epoxy resin-containing composition may be any curable composition, and may contain the epoxy resin and curing agent of the present invention. Furthermore, in epoxy resin-containing compositions, the epoxy resin of the present invention may be used alone as a resin component, or it may be used in combination with other resin components. Other epoxy resins, polyfunctional (meth)acrylate compounds, cyanate ester resins containing two or more cyanate groups, etc., may also be included. It is also preferable that the epoxy resin-containing composition contains a thermoplastic resin. Furthermore, epoxy resin-containing compositions used for prepreg applications may contain a flame retardant. Examples of flame retardants include phosphorus-containing compounds such as phosphate esters, nitrogen-containing compounds such as red phosphorus, melamine, melamine cyanurate, and melamine isocyanurate, metal hydroxides, and metal oxides. In epoxy resin-containing compositions used for prepreg applications, the epoxy resin content is preferably about 20 to 99% by mass, and more preferably about 50 to 80% by mass. The curing agent content is preferably 1 to 25% by mass, and more preferably 2 to 20% by mass.

[0085] (Electrical insulating materials and protective materials) The epoxy resin of the present invention may be used in electronic substrates and the like, and more specifically, it may be used as a protective material or an electrical insulating material for forming an electrical insulating layer. When used as an electrical insulating material or protective material, the curable resin composition of the present invention preferably contains a filler in addition to the epoxy resin and curing agent. The filler preferably has insulating properties. Examples of such fillers include silica, alumina, aluminum nitride, boron nitride, silicon carbide, and silicon nitride. In addition, a filler other than the inorganic filler described above may be used, and an organic filler may also 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 the solid content.

[0086] Curable resin compositions used for electrical insulating materials and protective materials may contain resins other than the epoxy resin of the present invention, for example, rubbery polymer compounds such as conjugated diene rubber. 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 the total amount of components other than fillers. Furthermore, epoxy resins other than the epoxy resin of the present invention may be contained, and thermosetting resins other than epoxy resins such as phenoxy resin may be contained. Silane coupling agents may also be contained. In curable resin compositions used for electrical insulating materials and protective materials, the epoxy resin content 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.

[0087] (Photosensitive resin) When used as an electrical insulating material or protective material for electronic circuit boards, the epoxy resin-containing composition may also be used as a photosensitive resin composition. In such cases, the composition may contain, in addition to the epoxy resin, 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 applications other than the protective materials and electrical insulating materials for electronic substrates described above. When used as a photosensitive resin composition, the epoxy resin of the present invention may be used in combination with photoacid generators such as iodonium salts, sulfonium salts, and pyridinium salts. A photoacid generator is an agent that generates acid upon light irradiation, and the epoxy resin is preferably polymerized by the acid produced by the decomposition of the photoacid generator. Furthermore, as described above, the applications of the photosensitive resin composition are not particularly limited, but include dental applications, more specifically, filling and restorative materials used to repair damaged teeth, denture base relining materials, and hybrid ceramics for crown restorations. It may also be used for lens applications, as described below.

[0088] (Lens applications) In lens applications, the epoxy resin of the present invention may be used in combination with other epoxy resins or resin components such as oxacene compounds. Therefore, epoxy resin-containing compositions for lens applications may contain other epoxy resins or oxacene compounds in addition to the epoxy resin of the present invention. Examples of other epoxy resins include diglycidyl ether compounds having a bisphenol skeleton, bifunctional alicyclic epoxy compounds without a bisphenol skeleton, and polyfunctional epoxy compounds with three or more functions having an isocyanurate ring structure. Furthermore, when used in lens applications, the epoxy resin-containing composition is preferably a photosensitive resin composition, and may contain, for example, the photoacid generator described above. The uses and specific formulations described above are merely examples, and the materials may be used for purposes other than those described above, and the formulations of each composition for each use may differ from those described above. [Examples]

[0089] The present invention will be described below with reference to examples, but the present invention is not limited in any way by these examples. This is not the case. The measurement conditions in the following examples are as follows.

[0090] <Measurement conditions> [ 1 [H-NMR spectral measurement] The NMR spectrometer "ECX400" manufactured by JEOL Ltd. was used, with deuterated dimethyl sulfoxide (deuterated DMSO) as the solvent, and measurements were taken at 23°C. [Two-dimensional HH COSY] Equipment used: JEOL Ltd. "ECX400" (400MHz) Solvent: DMSO-d6 Concentration and sample volume: Dissolve the sample in 0.8 mL of DMSO-d6. Reference material: None Measurement temperature: Room temperature Measurement parameters Pulse sequence: Standard COSY sequence (device default conditions) Total number of times: 4 (NS) Number of data points: X_point 1024 points, Y_point 256 points Spectral width: Measurement range: Observation center 5 [ppm], observation width 15 [ppm] Relaxation time: 1.5 [s] [Glass transition temperature (Tg)] A differential scanning calorimeter (product name "DSC-60") manufactured by Shimadzu Corporation was used to measure the temperature under a nitrogen atmosphere and a heating rate of 10°C / min. The midpoint of the baseline displacement was defined as the glass transition temperature. In this case, the temperature was raised to 200°C at a rate of 10°C / min, then cooled to -20°C, and then heated again at a rate of 10°C / min. [GPC] The GPC measurement method is as follows: Measurements were taken using a GPC system manufactured by Shimadzu Corporation. The conditions were as follows: Columns: Two SHODEX "KF803L" columns manufactured by Showa Denko (exclusion limit molecular weight 70,000) are used in series. Column temperature: 40°C, Flow rate: 1.0 ml / min, Eluent: Tetrahydrofuran Detectors: RI, UV (PDA) (Note that the samples consisted mostly of oligomers of HS quantities, and since the difference would be large if converted to the usual polystyrene equivalent, molecular weight and molecular weight distribution calculations were not performed.)

[0091] Manufacturing Example 1 [HS oligomer synthesis by alkaline treatment of p-coumaric acid] 2.0 g (50 mmol) of sodium hydroxide and 50 ml of deionized water were added to a mini separable flask and stirred with a stirrer to obtain a homogeneous aqueous solution. 8.2 g (50 mmol) of p-coumaric acid was added and dissolved. 50 ml of 1-methoxy-2-propanol was added to the resulting mixture, and then a Liebig condenser, a thermocouple for temperature measurement, and a three-way stopcock for nitrogen introduction were set up. The system was then purged with nitrogen while stirring at room temperature for several minutes. The heater was then set to 120°C and the reaction was carried out under reflux conditions for 4 hours. The reflux temperature was 98°C. After cooling, 50 ml of deionized water was added to dissolve the precipitated inorganic salts, and then 50 ml of ethyl acetate was added to obtain the organic phase. Subsequently, the target product was extracted from the aqueous phase three times with 50 ml of ethyl acetate, and the organic phase was dehydrated with anhydrous MgSO4, concentrated, and vacuum dried to obtain the target product, HS oligomer (hydroxystyrene polymer). The result was an orange, viscous liquid (some crystals later precipitated), with a yield of 5.44 g (91% yield). Dissolve in DMSO-d6. 1 The structure was confirmed by measuring 1H-NMR. The average degree of polymerization, calculated from the integrated protons of the vinyl group and aromatic ring, was 2.07. Furthermore, GPC measurements confirmed that the obtained HS oligomers were a mixture of dimers (m=1), trimers, tetramers, and pentamers or more. The RI area ratio in the GPC was 62 / 22 / 16 for dimers / trimers / tetramers or more.

[0092] The obtained HS oligomers were then subjected to column separation based on polarity to confirm the structure of the trimer. 1 Upon examination of the H-NMR spectrum and HH-COSY spectrum, it was determined that the main component is the compound shown in formula (I-4), and that the OG is a hydroxystyrene polymer in which the OG is a hydroxyl group rather than a glycidyloxy group. 1The 1H-NMR spectra and 1H-COSY spectra are shown in Figures 2 and 3, respectively. In Figure 2, the assignment of each peak is indicated, and the proton peaks enclosed by solid and dashed lines were confirmed by two-dimensional 1H-COSY. Furthermore, regarding the components obtained by further separation based on polarity: 1 Confirmation by H-NMR spectroscopy and HH-COSY spectroscopy revealed that the isolated component was a trimer represented by formula (I-1) with m = 2, and contained a hydroxystyrene polymer in which OG is a hydroxyl group rather than a glycidyloxy group. 1 The 1H-NMR and 1H-COSY spectra are shown in Figures 4 and 5. In Figure 4, the assignment of each peak is shown, and the proton peaks a to d were confirmed by two-dimensional 1H-COSY.

[0093] The reaction equation for the main reaction during the synthesis of the HS oligomer in Production Example 1 is shown below. [ka] In equation (VII), m is as described above.

[0094] Example 1 [Epoxy resin synthesis by glycidylation of HS oligomers] In a mini-separable flask, 3.6 g (30 mmol based on hydroxystyrene) of the HS oligomer obtained in Preparation Example 1 and 55.5 g (600 mmol) of epichlorohydrin were added and stirred with a stirrer to obtain a homogeneous solution. To this, 0.48 g (1.5 mmol) of tetrabutylammonium bromide (TBAB) was added and stirred. Then, a Liebig bottle cap, a thermocouple for temperature measurement, and a three-way stopcock for nitrogen introduction were set up, and the system was purged with nitrogen while stirring at room temperature for several minutes. After nitrogen purging, the system was heated at a heater temperature of 90°C and the reaction was continued for 6 hours, after which it was allowed to cool, and 41.7 g of a 4% by mass KOH / IPA solution was added dropwise at room temperature. Immediately after the start of dropwise addition, a white precipitate, presumably an inorganic salt, began to precipitate. After the dropwise addition was complete, 30 ml of deionized water was added to dissolve the precipitated salt. Then, 30 ml of ethyl acetate was added to separate the two phases, and the aqueous phase was separated. Subsequently, the organic phase was washed once with 30 ml of 1% by mass NaH2PO4 aqueous solution and twice with 30 ml of deionized water. After dehydration with anhydrous MgSO4, the solution was concentrated and vacuum dried to obtain the target epoxy resin. The result was a yellow-orange viscous liquid with a yield of 4.74 g (90% yield). The obtained epoxy resin was dissolved in DMSO-d6. 1 The structure was confirmed by measuring 1H-NMR. 1 The 1H-NMR spectrum is shown in Figure 1. The average degree of polymerization, determined from the integral values ​​of protons in the vinyl group and aromatic ring, was 1.97. Furthermore, from the GPC measurement results, it was confirmed that the obtained epoxy resin is a mixture of dimers (m=1), trimers, tetramers, and pentamers or more. In addition, based on the structure of the hydroxystyrene polymer, the trimer is thought to have the compound shown in formula (I-4) as its main component, and also to include the compound shown in formula (I-1) where m=2.

[0095] The reaction equation for the main reaction during epoxy resin synthesis in Example 1 is shown below. [ka] In equation (VIII) above, m is as described above.

[0096] Example 2 [Preparation of hardened material] 0.95 g of the epoxy resin obtained in Example 1 and 0.23 g of isophorone diamine were uniformly mixed and cured at 100°C for 1 hour, 160°C for 1 hour, and 200°C for 1 hour to obtain a cured product. The cured sample was finely crushed and the DSC was measured, revealing a glass transition temperature (Tg) of 149°C, which was almost equivalent to the good heat resistance observed when using a bisphenol A type epoxy resin with relatively good heat resistance, as demonstrated in Comparative Example 1 described later.

[0097] Example 3 An epoxy resin was synthesized in the same manner as in Example 1, using an HS dimer (i.e., the compound with m=1 in formula (VII)) separated by column chromatography from an HS oligomer synthesized in the same manner as in Production Example 1.

[0098] Example 4 Using the epoxy resin obtained in Example 3, a sample was obtained by curing it in the same manner as in Example 2, and the DSC was measured in the same manner as in Example 2. The glass transition temperature (Tg) was 147°C, which was almost equivalent to the good heat resistance observed when using a bisphenol A type epoxy resin with relatively good heat resistance, as demonstrated in Comparative Example 1 described later.

[0099] Comparative Example 1 0.95 g of bisphenol A type epoxy resin (Tokyo Chemical Co., Ltd.) and 0.21 g of isophorone diamine were uniformly mixed and cured under the same conditions as in Example 2. The glass transition temperature of the cured product was measured in the same manner as in Example 2, and the glass transition temperature (Tg) of the cured product was 153°C.

Claims

1. The epoxy resin represented by the following formula (I). 【Chemistry 1】 (In equation (I), m is an integer from 1 to 100, R １ ~R １０ Each of these is an organic group having 1 to 20 carbon atoms, which may independently have a hydrogen atom, a halogen atom, a hydroxyl group, or a heteroatom, and R １ ~R ５ At least one of and R ６ ~R １０ At least one of these is independently a hydroxyl group or a glycidyloxy group. R １１ and R １３ is a hydrogen atom, R １２ is a hydrogen atom or a group represented by the following formula (II), and has at least one glycidyloxy group in formula (I).) 【Chemistry 2】 (In equation (II), n is an integer from 1 to 100, R １４ ~R １８ Each of these is an organic group having 1 to 20 carbon atoms, which may independently have a hydrogen atom, a halogen atom, a hydroxyl group, or a heteroatom, and R １４ ~R １８ At least one of them is a hydroxyl group or a glycidyloxy group, R １９ * is a hydrogen atom, and * is R in formula (I). １２ (This indicates the bonding position in [the compound].) (However, m is 1, R ３ and R ８ is a glycidyl oxy group, R ２ and R ７ is a methoxy group, and R １ , R ４ ~R ６ , R ９ ~R １３ Compounds in which is a hydrogen atom, and m is 1, R ３ and R ８ is a glycidyl oxy group, R ２ , R ４ , R ７ and R ９ is a methoxy group, and R １ , R ５ , R ６ and R １０ ~R １３ (Excluding compounds in which the atom is a hydrogen atom.)

2. The epoxy resin according to claim 1, wherein m is 2 or more in formula (I).

3. R １ ~R ５ This is characterized by having at least one hydroxyl group or glycidyloxy group, and having a group adjacent to the hydroxyl group or glycidyloxy group that is other than a hydroxyl group, glycidyloxy group, and alkoxy group, R ６ ~R １０ This is characterized by having at least one hydroxyl group or glycidyloxy group, and having a group adjacent to the hydroxyl group or glycidyloxy group other than a hydroxyl group, glycidyloxy group, and alkoxy group. R １２ If the group is represented by formula (II), then R １４ ~R １８ The epoxy resin according to claim 1 or 2, wherein at least one of the groups is a hydroxyl group or a glycidyloxy group, and the group adjacent to the hydroxyl group or glycidyloxy group is other than a hydroxyl group, a glycidyloxy group, or an alkoxy group.

4. R １２ The epoxy resin according to claim 1 or 2, wherein is a hydrogen atom.

5. R １ ~R １０ Each of these is independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group, a glycidyloxy group, or a hydrocarbon group, and furthermore, R １２ If the group is represented by formula (II), then R １４ ~R １８ The epoxy resin according to claim 1 or 2, wherein each of them is independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group, a glycidyloxy group, or a hydrocarbon group.

6. R ３ and R ８ is a glycidyloxy group and R １ , R ２ , R ４ ~R ７ , and R ９ ~R １３ The epoxy resin according to claim 1 or 2, wherein is a hydrogen atom.

7. The epoxy resin according to claim 6, wherein m is 1.

8. A method for producing epoxy resin, comprising heating a compound represented by the following formula (III) in the presence of a basic substance to obtain a hydroxystyrene polymer, and then reacting the hydroxystyrene polymer with an epihalohydrin to obtain an epoxy resin. 【Transformation 3】 (In formula (III), R ２１ ~R ２５ Each of these is an organic group having 1 to 20 carbon atoms, which may independently have a hydrogen atom, a halogen atom, a hydroxyl group, or a heteroatom, and R ２１ ~R ２５ (At least one of them is a hydroxyl group.)

9. A method for producing an epoxy resin according to claim 8, comprising heating a compound represented by formula (III) in a mixed solvent of water and a specific organic solvent represented by the following formula (IV) in the presence of the basic substance to obtain the hydroxystyrene polymer. 【Chemistry 4】 (In formula (IV), R ２６ (This is an organic group having 1 to 10 carbon atoms, which may contain heteroatoms.)

10. In equation (IV), R ２６ A method for producing an epoxy resin according to claim 9, wherein the structure is represented by the following formula (V). 【Transformation 5】 (In formula (V), R ２７ R is an alkyl group having 1 to 4 carbon atoms. ２８ (where * indicates a hydrogen atom or methyl group, and * indicates the bond position to the hydroxyl group in formula (IV).)

11. In equation (V), R ２７ R is either a methyl group or an ethyl group, ２８ A method for producing an epoxy resin according to claim 10, wherein is a methyl group.

12. The method for producing an epoxy resin according to any one of claims 8 to 11, wherein the basic substance is at least one of an alkali metal or alkaline earth metal hydroxide, carbonate, or bicarbonate.

13. The method for producing an epoxy resin according to claim 12, wherein the basic substance is an alkali metal hydroxide.

14. A cured body obtained by curing an epoxy resin according to claim 1 or 2, or an epoxy resin obtained by a method for producing an epoxy resin according to any one of claims 8 to 11.

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