Curable epoxy composition

Abstract

Provided is a curable epoxy composition which can form a cured product having improved heat resistance, by using an alicyclic epoxy compound.　The curable epoxy composition includes: an alicyclic epoxy compound (A) having an alicyclic structure and an epoxy group in a molecule; nanodiamond particles (B); a curing agent (C); and a curing accelerator (D), or a curing catalyst (E). The nanodiamond particles (B) are dispersed in a matrix of the alicyclic epoxy compound (A), and the average dispersed particle diameter of the nanodiamond particles (B) in the curable epoxy composition is preferably 100 nm or less.

Description

[Technical Field]

[0001] The present disclosure relates to a curable epoxy composition. More particularly, the present disclosure relates to a curable epoxy composition containing an alicyclic epoxy compound. This application claims priority from Japanese Patent Application No. 2020-040922, filed on March 10, 2020, the contents of which are incorporated herein by reference. [Background technology]

[0002] In recent years, optical semiconductor devices have become increasingly powerful, and resins (encapsulants) that cover optical semiconductor elements in such optical semiconductor devices are required to have high heat resistance and light resistance. Conventionally, compositions containing, for example, epoxy compounds having an alicyclic structure (alicyclic epoxy compounds) have been known as encapsulants for forming encapsulants with high heat resistance (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 138988 [Non-patent literature]

[0004] [Non-Patent Document 1] Polymer, 2012, Issue 53, 5965-5971 Summary of the Invention [Problem to be solved by the invention]

[0005] Cured products of alicyclic epoxy compounds tend to have better heat resistance than cured products of other epoxy compounds, but even better heat resistance is sometimes required. Possible methods for improving the heat resistance of cured products using alicyclic epoxy compounds include developing new alicyclic epoxy compounds or examining the composition of compositions containing alicyclic epoxy compounds. However, these approaches may change the viscosity and physical properties of the alicyclic epoxy compound or composition, potentially resulting in a decrease in the performance of the cured product.

[0006] Incidentally, Non-Patent Document 1 discloses a composite material in which surface-aminated nanodiamonds are dispersed in a matrix of bisphenol A diglycidyl ether, an epoxy compound, and states that the Young's modulus of the epoxy compound can be improved by using this composite material (see Non-Patent Document 1).

[0007] However, Non-Patent Document 1 does not describe dispersing nanodiamond particles in alicyclic epoxy compounds, nor does it describe the heat resistance of epoxy compounds. Furthermore, it was confirmed that the nanodiamond particles partially formed aggregates in the composite material disclosed in Non-Patent Document 1, and the dispersibility was not sufficient.

[0008] Therefore, an object of the present disclosure is to provide a curable epoxy composition that uses an alicyclic epoxy compound and is capable of forming a cured product with improved heat resistance. [Means for solving the problem]

[0009] As a result of intensive research to achieve the above object, the inventors of the present disclosure have found that a curable epoxy composition containing an alicyclic epoxy compound and nanodiamond particles can be used to form a cured product with improved heat resistance. The present disclosure relates to a product that has been completed based on these findings.

[0010] The present disclosure provides a curable epoxy composition comprising an alicyclic epoxy compound (A) having an alicyclic structure and an epoxy group in the molecule, nanodiamond particles (B), a curing agent (C) and a curing accelerator (D) or a curing catalyst (E).

[0011] In the curable epoxy composition, the nanodiamond particles (B) are preferably dispersed in a matrix having the alicyclic epoxy compound (A) as a continuous phase.

[0012] The average primary particle size of the nanodiamond particles (B) in the curable epoxy composition is preferably 10 nm or less.

[0013] The average dispersed particle size of the nanodiamond particles (B) in the curable epoxy composition is preferably 100 nm or less.

[0014] The nanodiamond particles (B) preferably include surface-modified nanodiamond particles.

[0015] The surface modifying group that modifies the surface of the nanodiamond particle preferably has a group represented by the following formula (1). -X(-R 2 -X) n -R 1 (1) [In formula (1), X represents a linking group containing a heteroatom in the main chain. R 1 represents a substituted or unsubstituted monovalent organic group, and R 2 represents a substituted or unsubstituted divalent organic group, and R 1 and R 2 The atom bonded to X in formula (1) is a carbon atom. n represents an integer of 0 or more, and when n is an integer of 1 or more, the multiple Xs in formula (1) may be the same or different.]

[0016] In the above formula (1), X is preferably a linking group containing one or more heteroatoms selected from the group consisting of nitrogen atoms, oxygen atoms, and sulfur atoms in the main chain.

[0017] In the above formula (1), X is preferably -NH-, -O-, -OC(=O)-, -C(=O)-O-, -NH-C(=O)-, -C(=O)-NH-, -NH-C(=O)-O-, -OC(=O)-NH-, -S-, a divalent group in which two or more of these bonds are bonded together, or a group in which one or more of these bonds are bonded to -C(=O)-.

[0018] In the above formula (1), R 1 and R 2 The total number (molar ratio) of carbon atoms therein is preferably 1-8.

[0019] In the above formula (1), R 1 represents a substituted or unsubstituted monovalent hydrocarbon group, and R 2 preferably represents a substituted or unsubstituted divalent hydrocarbon group.

[0020] The above formula (1) may be a group represented by the following formula (2). -R 3 -X(-R 2 -X) n -R 1 (2) [In formula (2), R 3 represents a substituted or unsubstituted divalent organic group. The rest are the same as those in the above formula (1).

[0021] In the above formula (2), R 1 , R 2 , and R 3 The total number (molar ratio) of carbon atoms therein is preferably 1-8.

[0022] In the above formula (2), R 3 preferably represents a substituted or unsubstituted divalent hydrocarbon group.

[0023] R in the above formula (2) 3 The bond extending to the left from may be bonded to the nanodiamond particle via a silicon atom.

[0024] The alicyclic epoxy compound (A) preferably has two or more epoxy groups in the molecule.

[0025] The alicyclic epoxy compound (A) preferably contains (I) a compound having an epoxy group composed of two adjacent carbon atoms and an oxygen atom that constitute an alicyclic ring in the molecule, and / or (II) a compound having an epoxy group directly bonded to an alicyclic ring via a single bond.

[0026] The alicyclic epoxy compound (A) preferably contains a compound having a cyclohexene oxide group.

[0027] The present disclosure also provides a cured product of the curable epoxy composition.

[0028] The cured product preferably has a glass transition temperature of 120°C or higher.

[0029] The present disclosure also provides an optical member comprising the above cured product. [Effects of the Invention]

[0030] According to the curable epoxy composition of the present disclosure, a cured product with improved heat resistance can be formed while using an alicyclic epoxy compound. DETAILED DESCRIPTION OF THE INVENTION

[0031] [Curable Epoxy Composition] A curable epoxy composition according to one embodiment of the present disclosure is a curable composition comprising at least an alicyclic epoxy compound (A), nanodiamond particles (B), a curing agent (C), and a curing accelerator (D). Also, a curable epoxy composition according to another embodiment of the present disclosure is a curable composition comprising at least an alicyclic epoxy compound (A), nanodiamond particles (B), and a curing catalyst (E).

[0032] In the curable epoxy composition, the nanodiamond particles (B) are dispersed in a matrix having the alicyclic epoxy compound (A) as a continuous phase.

[0033] (Alicyclic epoxy compound (A)) The alicyclic epoxy compound (A) is a compound having one or more alicyclic rings (alicyclic structures) and one or more epoxy groups (oxirane rings) in the molecule. The alicyclic epoxy compound (A) preferably has two or more epoxy groups in the molecule.

[0034] The alicyclic epoxy compound (A) may be a known or conventional alicyclic epoxy compound, and is not particularly limited. Examples include (I) a compound having an epoxy group (referred to as an "alicyclic epoxy group") composed of two adjacent carbon atoms and an oxygen atom that constitute an alicyclic ring in the molecule; (II) a compound in which an epoxy group is directly bonded to an alicyclic ring via a single bond; and (III) a compound having an alicyclic ring and a glycidyl ether group in the molecule (glycidyl ether type epoxy compound).

[0035] The above (I) compound having an alicyclic epoxy group in the molecule includes a compound having a cyclohexene oxide group, such as a compound represented by the following formula (i). [ka]

[0036] In the above formula (i), Y represents a single bond or a linking group (a divalent group having one or more atoms). Examples of the linking group include a divalent hydrocarbon group, an alkenylene group in which some or all of the carbon-carbon double bonds have been epoxidized, a carbonyl group, an ether bond, an ester bond, a carbonate group, an amide group, and groups in which multiple of these are linked together. Note that a substituent such as an alkyl group may be bonded to one or more of the carbon atoms constituting the cyclohexane ring (cyclohexene oxide group) in formula (i).

[0037] Examples of the divalent hydrocarbon group include a linear or branched alkylene group having 1 to 18 carbon atoms and a divalent alicyclic hydrocarbon group. Examples of the linear or branched alkylene group having 1 to 18 carbon atoms include a methylene group, a methylmethylene group, a dimethylmethylene group, an ethylene group, a propylene group, and a trimethylene group. Examples of the divalent alicyclic hydrocarbon group include a divalent cycloalkylene group (including a cycloalkylidene group) such as a 1,2-cyclopentylene group, a 1,3-cyclopentylene group, a cyclopentylidene group, a 1,2-cyclohexylene group, a 1,3-cyclohexylene group, a 1,4-cyclohexylene group, and a cyclohexylidene group.

[0038] Examples of the alkenylene group in the alkenylene group in which some or all of the carbon-carbon double bonds have been epoxidized (sometimes referred to as an "epoxidized alkenylene group") include linear or branched alkenylene groups having 2 to 8 carbon atoms, such as vinylene, propenylene, 1-butenylene, 2-butenylene, butadienylene, pentenylene, hexenylene, heptenylene, and octenylene. In particular, the epoxidized alkenylene group is preferably an alkenylene group in which all of the carbon-carbon double bonds have been epoxidized, and more preferably an alkenylene group having 2 to 4 carbon atoms in which all of the carbon-carbon double bonds have been epoxidized.

[0039] Representative examples of the alicyclic epoxy compound represented by formula (i) above include (3,4,3',4'-diepoxy)bicyclohexyl and compounds represented by formulas (i-1) to (i-10) below. In formulas (i-5) and (i-7) below, l and m each represent an integer of 1 to 30. R' in formula (i-5) below is an alkylene group having 1 to 8 carbon atoms, and among these, a linear or branched alkylene group having 1 to 3 carbon atoms, such as a methylene group, an ethylene group, a propylene group, or an isopropylene group, is preferred. In formulas (i-9) and (i-10) below, n1 to n6 each represent an integer of 1 to 30. Other examples of the alicyclic epoxy compound represented by the above formula (i) include 2,2-bis(3,4-epoxycyclohexyl)propane, 1,2-bis(3,4-epoxycyclohexan-1-yl)ethane, 1,2-epoxy-1,2-bis(3,4-epoxycyclohexan-1-yl)ethane, and bis(3,4-epoxycyclohexylmethyl)ether. [ka] [ka]

[0040] Examples of the compound (II) in which an epoxy group is directly bonded to an alicyclic ring via a single bond include compounds represented by the following formula (ii). [ka]

[0041] In formula (ii), R" is a group (p-valent organic group) obtained by removing p hydroxyl groups (-OH) from the structural formula of a p-valent alcohol, and p and n each represent a natural number. pExamples of the compound represented by formula (ii) include polyhydric alcohols (e.g., alcohols having 1 to 15 carbon atoms) such as 2,2-bis(hydroxymethyl)-1-butanol. p is preferably 1 to 6, and n is preferably 1 to 30. When p is 2 or more, n in each group in ( ) (in the outer parentheses) may be the same or different. Specific examples of the compound represented by formula (ii) include 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol [for example, trade name "EHPE3150" (manufactured by Daicel Corporation)].

[0042] The above-mentioned (III) compounds having an alicyclic ring and a glycidyl ether group in the molecule include, for example, glycidyl ethers of alicyclic alcohols (particularly, alicyclic polyhydric alcohols). More specifically, for example, hydrogenated compounds of bisphenol A type epoxy compounds such as 2,2-bis[4-(2,3-epoxypropoxy)cyclohexyl]propane, 2,2-bis[3,5-dimethyl-4-(2,3-epoxypropoxy)cyclohexyl]propane (hydrogenated bisphenol A type epoxy compounds); bis[o,o-(2,3-epoxypropoxy)cyclohexyl]methane, bis[o,p-(2,3-epoxypropoxy)cyclohexyl]methane, bis[p,p-(2,3-epoxypropoxy)cyclohexyl]methane, bis[3,5-dimethyl-4- Examples of suitable epoxy compounds include hydrogenated compounds of bisphenol F epoxy compounds such as (2,3-epoxypropoxy)cyclohexyl)methane (hydrogenated bisphenol F epoxy compounds); hydrogenated biphenol epoxy compounds; hydrogenated phenol novolac epoxy compounds; hydrogenated cresol novolac epoxy compounds; hydrogenated cresol novolac epoxy compounds of bisphenol A; hydrogenated naphthalene epoxy compounds; hydrogenated epoxy compounds of epoxy compounds obtained from trisphenolmethane; and hydrogenated epoxy compounds of other epoxy compounds having an aromatic ring.

[0043] The content of the alicyclic epoxy compound (A) in the curable epoxy composition is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 50% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more, based on the total amount (100% by mass) of the curable epoxy composition. The content is, for example, 99.9999% by mass or less.

[0044] (Nanodiamond particles (B)) The nanodiamond particles (B) are nano-sized diamond particles and are not particularly limited, and known or conventional nanodiamond particles can be used. The nanodiamond particles (B) may be nanodiamond particles with a modified nanodiamond surface (surface-modified nanodiamond particles), or may be nanodiamond particles that are not surface-modified. Note that the non-surface-modified nanodiamond particles have hydroxy groups (-OH) on their surfaces. Among them, surface-modified nanodiamond particles are preferred from the viewpoint of excellent affinity with the alicyclic epoxy compound (A) and superior dispersibility of the nanodiamond particles in the alicyclic epoxy compound matrix. Only one type of nanodiamond particle (B) may be used, or two or more types may be used.

[0045] The nanodiamond particles (B) preferably contain primary particles of nanodiamond. In addition, they may contain secondary particles formed by aggregation (adhesion) of several to several tens of the above primary particles. Furthermore, when the nanodiamond particles (B) are surface-modified nanodiamond particles, the group (surface-modifying group) modifying the surface of the surface-modified nanodiamond particles may be only one type, or may be two or more types.

[0046] In the surface-modified nanodiamond, the surface modifying group preferably has a group represented by the following formula (1): By having the group represented by formula (1), heteroatoms and organic groups are present in a balanced manner in the surface modifying group present on the nanodiamond particle surface, so that the nanodiamond particles (B) have excellent affinity with the alicyclic epoxy compound (A) and the nanodiamond particles have excellent dispersibility in the alicyclic epoxy compound matrix. -X(-R 2 -X) n -R 1 (1) [In formula (1), X represents a linking group containing a heteroatom in the main chain. R 1 represents a substituted or unsubstituted monovalent organic group, and R 2 represents a substituted or unsubstituted divalent organic group, and R 1 and R 2 The atom bonded to X in formula (1) is a carbon atom. n represents an integer of 0 or more, and when n is an integer of 1 or more, the multiple Xs in formula (1) may be the same or different.]

[0047] X represents a linking group containing a heteroatom in the main chain. The main chain is a linking group between the nanodiamond particle and R in the formula (1). 1 The chain or R that connects 1 and R 2 The linking group may have a carbon atom in the main chain to which a heteroatom is directly bonded in a side chain, but the linking group does not have a carbon atom in the main chain to which a heteroatom is not directly bonded in a side chain. For example, -C(=O)- can be a linking group, but an unsubstituted methylene group is not included in the linking group.

[0048] The heteroatom in X is preferably a nitrogen atom, an oxygen atom, or a sulfur atom, more preferably an oxygen atom or a nitrogen atom. X may contain only one type of heteroatom, or may contain two or more types of heteroatoms.

[0049] Examples of X include -NH-, -O-, -OC(=O)-, -C(=O)-O-, -NH-C(=O)-, -C(=O)-NH-, -NH-C(=O)-O-, -OC(=O)-NH-, -S-, a divalent group in which two or more of these bonds are bonded, and a group in which one or more of these bonds are bonded to -C(=O)-. Among these, -O-, -OC(=O)- and -NH-C(=O)-O- are preferred.

[0050] R 1 represents a substituted or unsubstituted monovalent organic group. Examples of the monovalent organic group include monovalent hydrocarbon groups, monovalent heterocyclic groups, and groups in which two or more of these are combined. Examples of the monovalent hydrocarbon group include monovalent aliphatic hydrocarbon groups, monovalent alicyclic hydrocarbon groups, monovalent aromatic hydrocarbon groups, and groups in which two or more of these are combined.

[0051] Examples of the monovalent aliphatic hydrocarbon group include an alkyl group, an alkenyl group, and an alkynyl group. Examples of the alkyl group include a linear or branched alkyl group (preferably C 1 1-8 Alkyl groups, more preferably C 1-5 alkyl group, more preferably C 2-4 Examples of the alkenyl group include linear or branched alkenyl groups (preferably C 1 2-10 Alkenyl groups, more preferably C 2-5 Examples of the alkynyl group include linear or branched alkynyl groups (preferably C alkynyl groups) such as ethynyl and propynyl groups. 2-10 Alkynyl groups, more preferably C 2-5 alkynyl groups).

[0052] The monovalent aliphatic hydrocarbon group is preferably a linear or branched alkylene group or a linear or branched alkenylene group, more preferably a linear or branched alkylene group.

[0053] Examples of the monovalent alicyclic hydrocarbon group include C groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cyclododecyl group. 3-12 Cycloalkyl groups; C such as cyclohexenyl groups 3-12 Cycloalkenyl group; C such as bicycloheptanyl group, bicycloheptenyl group 4-15 Examples include a bridged cyclic hydrocarbon group.

[0054] Examples of the monovalent aromatic hydrocarbon group include C groups such as phenyl and naphthyl groups. 6-14 Aryl groups (especially C 6-10 aryl groups).

[0055] Examples of the heterocycle in the monovalent heterocyclic group include aromatic heterocycles and non-aromatic heterocycles. Examples of such heterocycles include 3- to 10-membered rings (preferably 4- to 6-membered rings) containing carbon atoms and at least one heteroatom (e.g., oxygen atom, sulfur atom, nitrogen atom, etc.) as ring-constituting atoms, and condensed rings thereof. Specific examples include heterocycles containing an oxygen atom as a heteroatom (e.g., 3-membered rings such as oxirane ring; 4-membered rings such as oxetane ring; 5-membered rings such as furan ring, tetrahydrofuran ring, oxazole ring, isoxazole ring, γ-butyrolactone ring; 6-membered rings such as 4-oxo-4H-pyran ring, tetrahydropyran ring, morpholine ring; condensed rings such as benzofuran ring, isobenzofuran ring, 4-oxo-4H-chromene ring, chroman ring, isochroman ring); 3-oxatricyclo[4.3.1.1 4,8 ]undecan-2-one ring, 3-oxatricyclo[4.2.1.0 4,8]nonan-2-one ring and the like), heterocycles containing a sulfur atom as a heteroatom (for example, five-membered rings such as a thiophene ring, a thiazole ring, an isothiazole ring, and a thiadiazole ring; six-membered rings such as a 4-oxo-4H-thiopyran ring; fused rings such as a benzothiophene ring), heterocycles containing a nitrogen atom as a heteroatom (for example, five-membered rings such as a pyrrole ring, a pyrrolidine ring, a pyrazole ring, an imidazole ring, and a triazole ring; six-membered rings such as an isocyanuric ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a piperidine ring, and a piperazine ring; and fused rings such as an indole ring, an indoline ring, a quinoline ring, an acridine ring, a naphthyridine ring, a quinazoline ring, and a purine ring).

[0056] Examples of the group in which the monovalent aliphatic hydrocarbon group and the monovalent alicyclic hydrocarbon group are bonded together include a cyclohexylmethyl group, a methylcyclohexyl group, etc. Examples of the group in which the monovalent aliphatic hydrocarbon group and the monovalent aromatic hydrocarbon group are bonded together include C groups such as a benzyl group and a phenethyl group. 7-18 Aralkyl groups (especially C 7-10 aralkyl group), cinnamyl group, etc. 6-10 Aryl-C 2-6 C such as alkenyl group, tolyl group 1-4 C such as alkyl-substituted aryl groups and styryl groups 2-4 Alkenyl-substituted aryl groups and the like are included.

[0057] The monovalent organic group may have a substituent. The substituent preferably has 0 to 20 carbon atoms, more preferably 1 to 10 carbon atoms. Examples of the substituent include alkoxy groups (preferably C alkoxy groups) such as methoxy, ethoxy, propoxy, isopropyloxy, butoxy, and isobutyloxy groups. 1-6 Alkoxy groups, more preferably C 1-4 Alkoxy group; alkenyloxy group such as allyloxy group (preferably C 2-6 Alkenyloxy groups, more preferably C 2-4 alkenyloxy group); phenoxy group, tolyloxy group, naphthyloxy group, etc., with C in the aromatic ring 1-4 Alkyl group, C 2-4Alkenyl group, C 1-4 An aryloxy group (preferably C) which may have a substituent such as an alkoxy group 6-14 aryloxy group; aralkyloxy group such as benzyloxy group, phenethyloxy group (preferably C 7-18 aralkyloxy groups; acyloxy groups such as acetyloxy groups, propionyloxy groups, (meth)acryloyloxy groups, and benzoyloxy groups (preferably C 1-12 acyloxy group; alkylthio group such as methylthio group, ethylthio group (preferably C 1-6 Alkylthio groups, more preferably C 1-4 Alkylthio group; alkenylthio group such as allylthio group (preferably C 2-6 Alkenylthio groups, more preferably C 2-4 alkenylthio group); phenylthio group, tolylthio group, naphthylthio group, etc., with C in the aromatic ring 1-4 Alkyl group, C 2-4 Alkenyl group, C 1-4 An arylthio group (preferably C) which may have a substituent such as an alkoxy group 6-14 arylthio group; aralkylthio group such as benzylthio group, phenethylthio group (preferably C 7-18 Aralkylthio groups; alkoxycarbonyl groups such as methoxycarbonyl groups, ethoxycarbonyl groups, propoxycarbonyl groups, and butoxycarbonyl groups (preferably C 1-6 Alkoxy-carbonyl group; aryloxycarbonyl group such as phenoxycarbonyl group, tolyloxycarbonyl group, naphthyloxycarbonyl group (preferably C 6-14 Aryloxycarbonyl group; aralkyloxycarbonyl group such as benzyloxycarbonyl group (preferably C 7-18 aralkyloxy-carbonyl group; dialkylamino group such as dimethylamino group or diethylamino group (preferably di-C 1-6 alkylamino group; acylamino group such as acetylamino group, propionylamino group, benzoylamino group (preferably C 1-11acylamino group; epoxy group-containing groups such as glycidyloxy group; oxetanyl group-containing groups such as ethyloxetanyloxy group; acyl groups such as acetyl group, propionyl group, and benzoyl group; oxo group; two or more of these may be optionally C 1-6 Examples include groups in which the terminal is an organic group, such as a group bonded via an alkylene group.

[0058] The monovalent organic group is preferably a monovalent hydrocarbon group, more preferably C 1-8 Hydrocarbon groups, more preferably C 1-5 Hydrocarbon groups, particularly preferably C 2-4 When the number of carbon atoms is within the above range, the dispersibility of the nanodiamond particles in the alicyclic epoxy compound matrix is ​​better.

[0059] R 2 represents a substituted or unsubstituted divalent organic group. Examples of the divalent organic group include a divalent hydrocarbon group, a divalent heterocyclic group, and a group in which two or more of these are bonded together. Examples of the divalent hydrocarbon group include a divalent aliphatic hydrocarbon group, a divalent alicyclic hydrocarbon group, a divalent aromatic hydrocarbon group, and a group in which two or more of these are bonded together.

[0060] Examples of the divalent aliphatic hydrocarbon group include an alkylene group, an alkenylene group, and an alkynylene group. Examples of the alkylene group include a linear or branched alkylene group (preferably C ) such as a methylene group, an ethylene group, a propylene group, an isopropylene group, a butylene group, a hexylene group, an octylene group, or an isooctylene group. 1-8 Alkylene groups, more preferably C 1-5 Alkylene groups, more preferably C 2-4 Examples of the alkenylene group include linear or branched alkenylene groups (preferably C 1 2-10 Alkenylene groups, more preferably C2-5 alkenylene groups).

[0061] The divalent aliphatic hydrocarbon group is preferably a linear or branched alkylene group or a linear or branched alkenylene group, more preferably a linear or branched alkylene group.

[0062] Examples of the divalent alicyclic hydrocarbon group include C groups such as a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, and a cyclododecylene group. 3-12 Cycloalkylene group; C such as cyclohexenylene group 3-12 Cycloalkenylene group; C such as bicycloheptanylene group, bicycloheptenylene group 4-15 Examples include a bridged cyclic hydrocarbon group.

[0063] Examples of the divalent aromatic hydrocarbon group include C phenylene groups, naphthylene groups, etc. 6-14 Arylene groups (especially C 6-10 arylene groups).

[0064] The heterocycle in the divalent heterocyclic group includes R 1 Examples of heterocycles in the monovalent heterocyclic group include those exemplified and explained in the above.

[0065] The divalent organic group may have a substituent. Examples of the substituent include R 1 In the above, examples of the substituent in the monovalent organic group include those exemplified and explained above. Other examples include a hydroxy group, an amino group, a carboxy group, a thiol group, and a halogen atom.

[0066] The divalent organic group is preferably a divalent hydrocarbon group, more preferably C 1-8 Hydrocarbon groups, more preferably C 1-5 Hydrocarbon groups, particularly preferably C 2-4When the number of carbon atoms is within the above range, the dispersibility of the nanodiamond particles in the alicyclic epoxy compound matrix is ​​better.

[0067] Specific examples of the group represented by the above formula (1) include alkoxy groups such as a methoxy group, an ethoxy group, a propyloxy group, a 1-methylethyloxy group, and a 2-methylethyloxy group; alkenyloxy groups such as a vinyloxy group; acyloxy groups such as an acryloyloxy group and a methacryloyloxy group; alkyl-substituted amino groups such as an aminomethyl group; 2 -X) n However, the (-R 2 -X) n is a polyoxyalkylene chain; (-R 2 -X) n is a polyglyceryl chain.

[0068] (-R 2 -X) n is a polyoxyalkylene chain, X represents an oxygen atom, and R 2 represents an alkylene group, preferably C 1-4 It is an alkylene group. 1-4 Examples of the alkylene group include an ethylene group, an isopropylene group, an isobutylene group, and a tetramethylene group. Among these, an ethylene group and an isopropylene group are preferred. When n is an integer of 2 or more, a plurality of R 2 may be the same or different. 2 are different, the oxyalkylene (-R 2 The bonding form of the oxyalkylene (-R 2-X) and represents an integer of 2 or more. n is preferably an integer of 2 to 50, more preferably an integer of 4 to 45, and even more preferably an integer of 6 to 40. When n is 2 or more, steric hindrance between the surface modifying groups increases, making them more likely to disperse in the matrix. When n is 50 or less, entanglement of the surface modifying groups is suppressed, making them more likely to disperse in the matrix. Furthermore, the properties as a diamond material are less likely to be impaired. Furthermore, X outside the parentheses in the above formula (1) is preferably -NH-C(=O)-O-.

[0069] Specific examples of the polyoxyalkylene chain include polyethylene glycol chains, polypropylene glycol chains, polytetramethylene glycol chains, and polybutylene glycol chains. Furthermore, in each surface modifying group, the polyoxyalkylene chain may consist of only one type of oxyalkylene, or may consist of two or more types of oxyalkylene. Examples of polyoxyalkylene chains consisting of two or more types of oxyalkylene include polyethylene glycol-polypropylene glycol chains. When the polyoxyalkylene chain consists of two or more types of oxyalkylene, the bonding form of the two or more types of oxyalkylene may be random, alternating, or block.

[0070] The polyoxyalkylene chain preferably has a number average molecular weight of 100 to 10,000, more preferably 200 to 5,000, even more preferably 300 to 4,000, still more preferably 400 to 2,500, and particularly preferably 500 to 3,000 as polyoxyalkylene.

[0071] The average degree of polymerization (number average degree of polymerization) of the oxyalkylene groups in the polyoxyalkylene chain is preferably 2 to 50, more preferably 4 to 45, and even more preferably 6 to 40. When the average degree of polymerization is 2 or more, the steric hindrance between the surface modifying groups becomes large, making them more likely to disperse in the matrix. When the average degree of polymerization is 50 or less, the surface modifying groups are prevented from becoming entangled with each other, making them more likely to disperse in the matrix. In addition, the properties of the diamond material are less likely to be impaired.

[0072] (-R 2 -X) n is a polyglycerol chain, (-R 2 -X) n is preferably a polyglycerol chain represented by the following formula (A): -(C3H6O2) p -(C3H5O2R a ) q - (A) [In formula (A), p and q each represent the average degree of polymerization of the repeating units in the parentheses, where p is a value of 0 or more, q is a value exceeding 0, and p+q represents an integer of 1 or more. a represents a monovalent organic group.

[0073] [C3H6O2] with p in the above formula (A) has one or more structures represented by the following formulas (a) to (c). -CH2-CHOH-CH2-O- (a) -CH2-CH(CH2OH)-O- (b) -CH(CH2OH)-CH2-O- (c)

[0074] In the above formula (A), q is added to [C3H5O2R a has one or more of the structures represented by the following formulas (d) to (f). -CH2-CH(OR a )-CH2-O- (d) -CH2-CH(CH2OR a )-O- (e) -CH(CH2OR a )-CH2-O- (f)

[0075] p+q is preferably 1 to 100, more preferably 2 to 40, and even more preferably 3 to 30. When p+q is 1 or more, the steric hindrance between the surface modification groups becomes large, making them more easily dispersed in the matrix. When p+q is 100 or less, the surface modification groups are prevented from becoming entangled with each other, making them more easily dispersed in the matrix. Furthermore, the properties of the nanodiamond material are less likely to be impaired. It is preferable that [q / (p+q)] is 0.6 or more (for example, 0.8 to 1.0).

[0076] The above average degree of polymerization is defined as the number of glycidol units constituting the polyglycerin chain bonded to one surface functional group of the raw nanodiamond, and the number of surface functional groups of the raw nanodiamond can be determined by measuring the elemental analysis value of the raw nanodiamond, measuring the acid value, or a combination of both.

[0077] In the above formula (1), R 1 and R 2 The total number of carbon atoms (molar ratio) therein is preferably 1 to 8, more preferably 1 to 3, and even more preferably 1 to 2. When the molar ratio is within the above range, heteroatoms and organic groups are present in a well-balanced manner in the surface modifying groups present on the nanodiamond particle surface, so that the nanodiamond particles (B) have a better affinity with the alicyclic epoxy compound (A) and the nanodiamond particles have better dispersibility in the alicyclic epoxy compound matrix.

[0078] In the above formula (1), the bond extending to the left from X (X outside the parentheses) is directly or indirectly bonded to the nanodiamond particle. In the above formula (1), it is preferable that the bond extending to the left from X (X outside the parentheses) is bonded to a divalent organic group. In other words, it is preferable that the group represented by the above formula (1) is a group represented by the following formula (2). -R 3 -X(-R 2 -X) n -R 1 (2) [In formula (2), R 3represents a substituted or unsubstituted divalent organic group. The rest are the same as those in the above formula (1).

[0079] R 3 represents a substituted or unsubstituted divalent organic group. The divalent organic group is R in the above formula (1). 2 The divalent organic groups exemplified and described as:

[0080] R 3 The divalent organic group in is preferably a divalent hydrocarbon group, more preferably C 1-20 Hydrocarbon groups, more preferably C 1-10 Hydrocarbon groups, particularly preferably C 1-5 When the number of carbon atoms is within the above range, the dispersibility of the nanodiamond particles in the alicyclic epoxy compound matrix is ​​better.

[0081] In the above formula (2), R 1 , R 2 , and R 3 The total number of carbon atoms (molar ratio) therein is preferably 1 to 8, more preferably 1 to 3, and even more preferably 1 to 2. When the molar ratio is within the above range, heteroatoms and organic groups are present in a well-balanced manner in the surface modifying groups present on the nanodiamond particle surface, so that the nanodiamond particles (B) have a better affinity with the alicyclic epoxy compound (A) and the nanodiamond particles have better dispersibility in the alicyclic epoxy compound matrix.

[0082] In the above formula (2), R 3 The bond extending to the left from is directly or indirectly bonded to the nanodiamond particle. 3 The bond extending to the left from may be bonded to the nanodiamond particle via a silicon atom. In this case, R 3Preferably, the bond extending to the left from is bonded to a silicon atom. The group represented by the above formula (2) is preferably a group represented by the following formula (3). Such surface modifying groups are easy to introduce onto the surface of nanodiamond particles. -O-Si-R 3 -X(-R 2 -X) n -R 1 (3)

[0083] In the above formula (3), the bond extending to the left from the oxygen atom is bonded to the nanodiamond particle. The silicon atom in formula (3) is bonded to the oxygen atom and R 3 In addition, it bonds to a hydrogen atom, an aliphatic hydrocarbon group having 1 to 3 carbon atoms, a nanodiamond particle, or a silicon atom via an oxygen atom.

[0084] In the above formula (3), the structure in which a silicon atom is bonded to a hydrogen atom via an oxygen atom represents a structure in which an unreacted alkoxysilyl group in the group represented by the above formula (3) bonded to the nanodiamond particle is hydrolyzed. In addition, in the above formula (3), the structure in which a silicon atom is bonded to an aliphatic hydrocarbon group having 1 to 3 carbon atoms via an oxygen atom represents a structure in which an unreacted alkoxysilyl group remains in the group represented by the above formula (3) bonded to the nanodiamond particle. In addition, the structure in which a silicon atom is bonded to a silicon atom in a silicon atom via an oxygen atom represents a structure in which an unreacted alkoxysilyl group in the group represented by the above formula (3) bonded to the nanodiamond particle is reacted with an unreacted silane coupling agent (described below) or an alkoxysilyl group in another group represented by the above formula (3) bonded to the nanodiamond particle by dehydration condensation.

[0085] Zirconia may be attached (fixed) to the surface-modified nanodiamond. The surface-modified nanodiamond with zirconia attached thereto may be referred to as a "surface-modified nanodiamond composite." In other words, the surface-modified nanodiamond composite includes the surface-modified nanodiamond and zirconia attached to the surface-modified nanodiamond. The state of attachment of zirconia may be physical (fixed, adhered, etc.), chemical (covalent bond with nanodiamond particles or surface-modifying groups, bond due to intermolecular forces, hydrogen bond, ionic bond, etc.), or both. Only one type of zirconia may be used, or two or more types may be used.

[0086] As the nanodiamond particles (B) or the nanodiamond particles before surface modification in the above-mentioned surface-modified nanodiamond particles, for example, detonation nanodiamonds (i.e., nanodiamonds produced by detonation) or high-temperature high-pressure nanodiamonds (i.e., nanodiamonds produced by high-temperature high-pressure) can be used.Among them, detonation nanodiamonds are preferred because they tend to have many functional groups for introducing surface modification groups, and have better dispersibility in the matrix, that is, the particle size of the primary particles is one digit nanometer.

[0087] The detonation nanodiamonds include air-cooled detonation nanodiamonds (i.e., nanodiamonds produced by air-cooled detonation) and water-cooled detonation nanodiamonds (i.e., nanodiamonds produced by water-cooled detonation).Among them, air-cooled detonation nanodiamonds are preferred because their primary particles are smaller than those of water-cooled detonation nanodiamonds.

[0088] Surface-modified nanodiamond particles having a surface modification group containing a group represented by the above formula (3) can be produced, for example, through a modification process in which nanodiamond particles having a hydroxyl group (-OH) on the surface are reacted with a specific silane coupling agent. Note that nanodiamond particles that are not surface-modified usually have a hydroxyl group on the surface. The specific silane coupling agent is a compound in which the silicon atom in the group represented by the above formula (3) is R 3 The other three bonds are connected to C via an oxygen atom. 1-3 It is a compound bonded to an aliphatic hydrocarbon group.

[0089] The modification step is carried out by stirring a mixed solution containing dried nanodiamonds, a silane coupling agent, and a solvent in a reaction vessel.

[0090] Examples of the solvent include water, organic solvents, and ionic liquids. Examples of the organic solvent include aliphatic hydrocarbons (e.g., linear saturated aliphatic hydrocarbons) such as hexane, heptane, and octane; aromatic hydrocarbons such as benzene, toluene, and xylene; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; aprotic polar solvents such as dimethylformamide (DMF), dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide; halogenated hydrocarbons such as chloroform, dichloromethane, dichloroethane, carbon tetrachloride, chlorobenzene, and trifluoromethylbenzene; linear or cyclic ethers such as diethyl ether, diisopropyl ether, dimethoxyethane, tetrahydrofuran (THF), and dioxane; esters such as ethyl acetate and butyl acetate; linear ketones such as methyl ethyl ketone (MEK) and methyl isobutyl ketone; and nitriles such as acetonitrile. Among these, cyclic ethers (e.g., THF) and linear ketones (e.g., MEK and MIBK) are preferred. One or more of the solvents may be used.

[0091] In the modification step, if the nanodiamond particles contain nanodiamond particle aggregates (aggregates) formed by the aggregation of nanodiamond particles to form secondary particles, the reaction between the silane coupling agent and the nanodiamond particles may be carried out while the nanodiamond particles are being crushed or dispersed. This allows the nanodiamond particle aggregates to be crushed into primary particles, the surfaces of the primary nanodiamond particles to be modified, and the dispersibility of the nanodiamond particles (B) to be improved.

[0092] Methods for crushing or dispersing nanodiamond particles include, for example, processing using a high-shear mixer, high-shear mixer, homomixer, ball mill, bead mill, high-pressure homogenizer, ultrasonic homogenizer, colloid mill, jet mill, etc. Among these, ultrasonic treatment in the presence of crushing media (e.g., zirconia beads, etc.) is preferred. Using zirconia beads as crushing media can also result in the above-mentioned surface-modified nanodiamond composites and curable epoxy compositions containing zirconia. Ultrasonic treatment generates cavitation (microbubbles), and the jet stream generated when the cavitation collapses provides the crushing media with extremely high kinetic energy. The crushing media then collide with the nanodiamond aggregates, imparting impact energy, which disintegrates (crushes) the nanodiamond particles from the nanodiamond aggregates. A silane coupling agent acts on the dissociated nanodiamond particles, bonding them together. If the nanodiamond particles (B) contain nanodiamond aggregates formed by the adhesion of nanodiamond particles, these nanodiamond aggregates can be broken down into primary particles, the surfaces of the primary nanodiamond particles can be modified, and surface-modified nanodiamonds with excellent dispersibility in the matrix can be obtained.

[0093] The diameter of the above-mentioned crushing media (for example, zirconia beads) is, for example, 15 to 500 μm, preferably 15 to 300 μm, and particularly preferably 15 to 100 μm.

[0094] The ratio (mass ratio) of the nanodiamond particles to the silane coupling agent used in the reaction is, for example, 2:1 to 1:80. The concentration of the nanodiamond particles in the solvent is, for example, 0.5 to 10% by mass, and the concentration of the silane coupling agent in the solvent is, for example, 5 to 60% by mass.

[0095] The reaction time between the nanodiamond particles and the silane coupling agent is, for example, 4 to 20 hours. The reaction is preferably carried out while cooling the generated heat with ice water or the like.

[0096] The average primary particle diameter of the nanodiamond particles (B) in the curable epoxy composition is, for example, 10 nm or less, preferably 8 nm or less, and more preferably 7 nm or less. The lower limit of the average primary particle diameter is, for example, 2 nm. The smaller the average primary particle diameter, the better the dispersibility in the curable epoxy composition, and the better the heat resistance of the cured product. The average primary particle diameter of the nanodiamond particles (B) is the average value of the primary particle diameters of each nanodiamond particle (B) dispersed in the curable epoxy composition. For example, when nanodiamond particles produced by a detonation method or surface-modified products thereof are used as the nanodiamond particles (B), the average primary particle diameter tends to be within the above range.

[0097] The average dispersed particle size of the nanodiamond particles (B) in the curable epoxy composition is, for example, 100 nm or less, preferably 50 nm or less, and more preferably 40 nm or less. The lower limit of the average dispersed particle size is, for example, 5 nm. The smaller the average dispersed particle size, the more improved the heat resistance of the cured product. The average dispersed particle size of the nanodiamond particles (B) in the curable epoxy composition may be calculated as the average dispersed particle size of the nanodiamond particles (B) in the cured product obtained by curing the curable epoxy composition. Since it is unlikely that the nanodiamond particles (B) will disperse or aggregate significantly upon curing the curable epoxy composition, if the average dispersed particle size of the nanodiamond particles (B) in the cured product is within the above range, it can be determined that the average dispersed particle size of the nanodiamond particles (B) in the curable composition is also within the above range. In other words, the average dispersed particle size of the nanodiamond particles (B) in the cured product is preferably within the above range. The above-mentioned average dispersed particle diameter can be calculated by measuring the longest length of each of 300 dispersed nanodiamond particles (or aggregates of dispersed nanodiamond particles in the case of aggregates) in an image obtained by observation of the curable epoxy composition or cured product with a transmission electron microscope (TEM), and taking the average of these.

[0098] The content of the nanodiamond particles (B) in the curable epoxy composition is not particularly limited, but is, for example, 0.1 ppm to 10% by mass relative to the total amount (100% by mass) of the curable epoxy composition. The content of the nanodiamond particles (B) in the curable epoxy composition is, for example, 0.01 to 50 parts by mass, preferably 0.05 to 40 parts by mass, and more preferably 0.1 to 10 parts by mass relative to 100 parts by mass of the total amount of the alicyclic epoxy compound (A).

[0099] The content of nanodiamond particles (B) can be calculated from the absorbance at 350 nm. If the content of surface-modified nanodiamond particles is low (for example, 2000 mass ppm or less), the compound that has surface-modified the nanodiamond particles can be detected by high-frequency inductively coupled plasma atomic emission spectroscopy (ICP atomic emission spectroscopy) and the content can be determined based on the amount detected.

[0100] The content of zirconia in the curable epoxy composition is, for example, 0.001 to 10 mass%, preferably 0.01 to 1.0 mass%, and more preferably 0.05 to 0.5 mass%, relative to the total amount (100 mass%) of the curable epoxy composition.

[0101] The zirconia content can be determined by detecting Zr by high-frequency inductively coupled plasma atomic emission spectroscopy (ICP atomic emission spectroscopy) and based on the amount of Zr detected using a dispersion with a known content as a standard.

[0102] The mass ratio of zirconia to the surface-modified nanodiamond particles in the curable epoxy composition [former / latter] is, for example, 0.01 to 1.0, preferably 0.05 to 0.75, and more preferably 0.1 to 0.5. When the mass ratio is 0.01 or more, the effect of including zirconia can be more fully exhibited. When the mass ratio is 1.0 or less, the effect of the surface-modified nanodiamond particles can be more fully exhibited.

[0103] (Curing agent (C)) The curing agent (C) is a compound that reacts with a compound having an epoxy group, such as the alicyclic epoxy compound (A), to cure the curable epoxy composition. The curing agent (C) can be any known or conventional curing agent for epoxy resins, and is not particularly limited. Examples of the curing agent include, but are not limited to, acid anhydrides (acid anhydride curing agents), amines (amine curing agents), polyamide resins, imidazoles (imidazole curing agents), polymercaptans (polymercaptan curing agents), phenols (phenol curing agents), polycarboxylic acids, dicyandiamides, and organic acid hydrazides. The curing agent (C) may be used alone or in combination.

[0104] As the acid anhydride (acid anhydride-based curing agent) as the curing agent (C), known or conventional acid anhydride-based curing agents can be used, and are not particularly limited. Examples thereof include methyltetrahydrophthalic anhydride (4-methyltetrahydrophthalic anhydride, 3-methyltetrahydrophthalic anhydride, etc.), methylhexahydrophthalic anhydride (4-methylhexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, etc.), dodecenyl succinic anhydride, methyl-endomethylenetetrahydrophthalic anhydride, phthalic anhydride, maleic anhydride, tetrahydrophthalic anhydride, heptane Examples of suitable acid anhydrides include hexahydrophthalic anhydride, methylcyclohexene dicarboxylic anhydride, pyromellitic anhydride, trimellitic anhydride, benzophenone tetracarboxylic anhydride, nadic anhydride, methyl nadic anhydride, hydrogenated methyl nadic anhydride, 4-(4-methyl-3-pentenyl)tetrahydrophthalic anhydride, succinic anhydride, adipic anhydride, sebacic anhydride, dodecanedioic anhydride, methylcyclohexene tetracarboxylic anhydride, vinyl ether-maleic anhydride copolymer, and alkylstyrene-maleic anhydride copolymer. Among these, from the viewpoint of handleability, acid anhydrides that are liquid at 25° C. [e.g., methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, dodecenyl succinic anhydride, methylendomethylenetetrahydrophthalic anhydride, etc.] are preferred. On the other hand, when an acid anhydride that is solid at 25° C. is dissolved in an acid anhydride that is liquid at 25° C. to form a liquid mixture, the handleability of the curing agent in the curable epoxy composition tends to be improved. From the viewpoint of the heat resistance and transparency of the cured product, the acid anhydride-based curing agent is preferably an anhydride of a saturated monocyclic hydrocarbon dicarboxylic acid (including those having a substituent such as an alkyl group bonded to the ring).

[0105] As the amines (amine-based curing agents) as the curing agent (C), known or conventional amine-based curing agents can be used, and are not particularly limited. Examples thereof include aliphatic polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenediamine, diethylaminopropylamine, and polypropylenetriamine; menthenediamine, isophoronediamine, bis(4-amino-3-methyldicyclohexyl)methane, diaminodicyclohexylmethane, bis(aminomethyl)cyclohexane, N-aminoethylpiperazine, Examples include alicyclic polyamines such as 3,9-bis(3-aminopropyl)-3,4,8,10-tetraoxaspiro[5,5]undecane; mononuclear polyamines such as m-phenylenediamine, p-phenylenediamine, tolylene-2,4-diamine, tolylene-2,6-diamine, mesitylene-2,4-diamine, 3,5-diethyltolylene-2,4-diamine, and 3,5-diethyltolylene-2,6-diamine; and aromatic polyamines such as biphenylenediamine, 4,4-diaminodiphenylmethane, 2,5-naphthylenediamine, and 2,6-naphthylenediamine.

[0106] As the phenol (phenol-based curing agent) as the curing agent (C), known or commonly used phenol-based curing agents can be used, and although not particularly limited, examples thereof include aralkyl resins such as novolac-type phenolic resins, novolac-type cresol resins, paraxylylene-modified phenolic resins, and paraxylylene-metaxylylene-modified phenolic resins, terpene-modified phenolic resins, dicyclopentadiene-modified phenolic resins, and triphenolpropane.

[0107] Examples of polyamide resins as the curing agent (C) include polyamide resins having either or both of a primary amino group and a secondary amino group in the molecule.

[0108] As the imidazoles (imidazole-based curing agents) as the curing agent (C), known or conventional imidazole-based curing agents can be used, and are not particularly limited. Examples thereof include, but are not limited to, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, and 1-methylimidazole. ethyl-2-undecylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2-methylimidazolium isocyanurate, 2-phenylimidazolium isocyanurate, 2,4-diamino-6-[2-methylimidazolyl-(1)]-ethyl-s-triazine, 2,4-diamino-6-[2-ethyl-4-methylimidazolyl-(1)]-ethyl-s-triazine, and the like.

[0109] Examples of polymercaptans (polymercaptan-based curing agents) as the curing agent (C) include liquid polymercaptan and polysulfide resins.

[0110] Examples of polycarboxylic acids as the curing agent (C) include adipic acid, sebacic acid, terephthalic acid, trimellitic acid, and carboxy group-containing polyesters.

[0111] Among these, acid anhydrides (acid anhydride curing agents) are preferred as the curing agent (C) from the viewpoint of heat resistance and transparency of the cured product.

[0112] The content (amount) of the curing agent (C) in the curable epoxy composition is not particularly limited, but is preferably 50 to 200 parts by mass, more preferably 80 to 150 parts by mass, per 100 parts by mass of the total amount of epoxy group-containing compounds (e.g., alicyclic epoxy compound (A)) contained in the curable epoxy composition. More specifically, when an acid anhydride is used as the curing agent (C), it is preferably used in a proportion of 0.5 to 1.5 equivalents per equivalent of epoxy groups in all epoxy group-containing compounds contained in the curable epoxy composition. By using a content of the curing agent (C) of 50 parts by mass or more, curing can be sufficiently promoted, and the toughness of the cured product tends to be further improved. On the other hand, by using a content of the curing agent (C) of 200 parts by mass or less, coloration is further suppressed, and a cured product with excellent hue tends to be obtained.

[0113] (Curing accelerator (D)) The curing accelerator (D) is a compound that has the function of accelerating the reaction rate when a compound having an epoxy group reacts with the curing agent (C). Known or conventional curing accelerators can be used as the curing accelerator (D), and are not particularly limited. Examples of the curing accelerator include 1,8-diazabicyclo[5.4.0]undecene-7 (DBU) or its salts (e.g., phenol salt, octylate salt, p-toluenesulfonate, formate salt, tetraphenylborate salt, etc.); 1,5-diazabicyclo[4.3.0]nonene-5 (DBN) or its salts (e.g., phenol salt, octylate salt, p-toluenesulfonate, formate salt, tetraphenylborate salt, etc.); benzyldimethylamine, 2,4,6-tris(dimethylamine), Examples of the curing accelerator (D) include tertiary amines such as 2-ethyl-4-methylimidazole and N,N-dimethylcyclohexylamine; imidazoles such as 2-ethyl-4-methylimidazole and 1-cyanoethyl-2-ethyl-4-methylimidazole; phosphate esters; phosphines such as triphenylphosphine and tris(dimethoxy)phosphine; phosphonium compounds such as tetraphenylphosphonium tetra(p-tolyl)borate; organic metal salts such as zinc octoate, tin octoate, and zinc stearate; and metal chelates such as aluminum acetylacetone complex. One or more types of the curing accelerator (D) may be used.

[0114] The content (amount) of the curing accelerator (D) in the curable epoxy composition is not particularly limited, but is preferably 0.01 to 5 parts by mass, more preferably 0.03 to 3 parts by mass, and even more preferably 0.03 to 2 parts by mass, per 100 parts by mass of the total amount of compounds having an epoxy group contained in the curable epoxy composition. By setting the content of the curing accelerator (D) to 0.01 parts by mass or more, a more efficient curing acceleration effect tends to be obtained. On the other hand, by setting the content of the curing accelerator (D) to 5 parts by mass or less, coloration is further suppressed, and a cured product with excellent hue tends to be obtained.

[0115] (Curing catalyst (E)) The curing catalyst (E) is a compound that initiates and / or accelerates the curing reaction (polymerization reaction) of a cationically polymerizable compound such as the alicyclic epoxy compound (A), thereby curing the curable epoxy composition. The curing catalyst (E) is not particularly limited, but examples thereof include cationic polymerization initiators (e.g., photocationic polymerization initiators, thermal cationic polymerization initiators, etc.) that generate cationic species and initiate polymerization upon exposure to light or heat treatment, Lewis acid-amine complexes, Bronsted acid salts, and imidazoles. The curing catalyst (E) may be used singly or in combination of two or more.

[0116] Examples of the photocationic polymerization initiator as the curing catalyst (E) include hexafluoroantimonate salts, pentafluorohydroxyantimonate salts, hexafluorophosphate salts, and hexafluoroarsenate salts. More specific examples include sulfonium salts (particularly triarylsulfonium salts) such as triarylsulfonium hexafluorophosphate (e.g., p-phenylthiophenyldiphenylsulfonium hexafluorophosphate) and triarylsulfonium hexafluoroantimonate; iodonium salts such as diaryliodonium hexafluorophosphate, diaryliodonium hexafluoroantimonate, bis(dodecylphenyl)iodonium tetrakis(pentafluorophenyl)borate, and iodonium [4-(4-methylphenyl-2-methylpropyl)phenyl]hexafluorophosphate; phosphonium salts such as tetrafluorophosphonium hexafluorophosphate; and pyridinium salts such as N-hexylpyridinium tetrafluoroborate.

[0117] Examples of the thermal cationic polymerization initiator as the curing catalyst (E) include aryl diazonium salts, aryliodonium salts, arylsulfonium salts, allene ion complexes, etc. Further examples of the thermal cationic polymerization initiator include a compound of a chelate compound of a metal such as aluminum or titanium with acetoacetic acid or a diketone and a silanol such as triphenylsilanol, or a compound of a chelate compound of a metal such as aluminum or titanium with acetoacetic acid or a diketone and a phenol such as bisphenol S.

[0118] The Lewis acid-amine complex used as the curing catalyst (E) may be a known or conventional Lewis acid-amine complex curing catalyst, and may include, but is not limited to, BF3·n-hexylamine, BF3·monoethylamine, BF3·benzylamine, BF3·diethylamine, BF3·piperidine, BF3·triethylamine, BF3·aniline, BF4·n-hexylamine, BF4·monoethylamine, BF4·benzylamine, BF4·diethylamine, BF4·piperidine, BF4·triethylamine, BF4·aniline, PF5·ethylamine, PF5·isopropylamine, PF5·butylamine, PF5·laurylamine, PF5·benzylamine, and AsF5·laurylamine.

[0119] As the Brønsted acid salt as the curing catalyst (E), known or conventional Brønsted acid salts can be used, and although not particularly limited, examples thereof include aliphatic sulfonium salts, aromatic sulfonium salts, iodonium salts, and phosphonium salts.

[0120] As the imidazole as the curing catalyst (E), known or conventional imidazoles can be used, and are not particularly limited. Examples thereof include, but are not limited to, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-methylimidazole, Examples include undecylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2-methylimidazolium isocyanurate, 2-phenylimidazolium isocyanurate, 2,4-diamino-6-[2-methylimidazolyl-(1)]-ethyl-s-triazine, and 2,4-diamino-6-[2-ethyl-4-methylimidazolyl-(1)]-ethyl-s-triazine.

[0121] The content (amount) of the curing catalyst (E) in the curable epoxy composition is not particularly limited, but is preferably 0.01 to 15 parts by mass, more preferably 0.01 to 12 parts by mass, even more preferably 0.05 to 10 parts by mass, and particularly preferably 0.05 to 8 parts by mass, relative to 100 parts by mass of the total amount of the cationically polymerizable compounds contained in the curable epoxy composition. Using the curing catalyst (E) within the above range tends to increase the curing rate of the curable epoxy composition and improve the heat resistance and transparency of the cured product in a balanced manner.

[0122] The curable epoxy composition may contain a cationic curable compound other than the alicyclic epoxy compound (A). The content of the alicyclic epoxy compound (A) among the cationic curable compounds in the curable epoxy composition is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more, based on the total amount (100% by mass) of all cationic curable compounds in the curable epoxy composition. In addition, the content of the alicyclic epoxy compound (A) in 100% by mass of compounds having epoxy groups contained in the curable epoxy composition is preferably within the above range.

[0123] The curable epoxy composition may contain other components in addition to the above-mentioned components. For example, the addition of a compound having a hydroxy group, such as ethylene glycol, diethylene glycol, propylene glycol, or glycerin, can slow the reaction. Other additives that can be used within the range that does not impair viscosity or transparency include silicone-based or fluorine-based antifoaming agents, leveling agents, coupling agents such as silane coupling agents such as γ-glycidoxypropyltrimethoxysilane and 3-mercaptopropyltrimethoxysilane, surfactants, inorganic fillers such as silica and alumina, flame retardants, colorants, antioxidants, UV absorbers, ion adsorbents, colorants, phosphors (e.g., inorganic phosphor particles such as YAG-based phosphor particles and silicate-based phosphor particles), release agents, thickeners, dispersants, rust inhibitors, corrosion inhibitors, freezing point depressants, and anti-wear additives.

[0124] The curable epoxy composition can be prepared by stirring and mixing the above-mentioned components, optionally with heating, without any particular limitation. The curable epoxy composition can be used as a one-component composition in which the components are premixed and used as is, or as a multi-component (e.g., two-component) composition in which, for example, two or more components stored separately are mixed before use. The stirring and mixing method is not particularly limited, and known or conventional stirring and mixing means can be used, such as various mixers such as dissolvers and homogenizers, kneaders, rolls, bead mills, and planetary stirring devices. After stirring and mixing, the mixture may be degassed under vacuum.

[0125] The curable epoxy composition is preferably liquid at 25°C. The viscosity of the curable epoxy composition at 25°C is not particularly limited, but is preferably 100 to 10,000 mPa·s, more preferably 200 to 9,000 mPa·s, and even more preferably 300 to 8,000 mPa·s. A viscosity of 100 mPa·s or higher at 25°C tends to improve workability during casting and further improve the heat resistance of the cured product. On the other hand, a viscosity of 10,000 mPa·s or lower at 25°C tends to improve workability during casting and reduce the occurrence of defects in the cured product due to poor casting. The viscosity of the curable epoxy composition at 25°C can be measured, for example, using a digital viscometer (model number "DVU-EII" manufactured by Tokimec Inc.) under the following conditions: rotor: standard 1°34' x R24, temperature: 25°C, and rotation speed: 0.5 to 10 rpm.

[0126] [Cured product] By curing the curable epoxy composition, a cured product with excellent heat resistance can be obtained. Curing can be achieved by known or conventional methods such as heat treatment or light irradiation. The temperature (curing temperature) for curing by heating is not particularly limited, but is preferably 45 to 200°C, more preferably 50 to 190°C, and even more preferably 55 to 180°C. The heating time (curing time) for curing is also not particularly limited, but is preferably 30 to 600 minutes, more preferably 45 to 540 minutes, and even more preferably 60 to 480 minutes. A curing temperature and curing time of 45°C or higher ensures sufficient curing, while a curing temperature of 200°C or lower can suppress decomposition of the resin component. Curing conditions vary depending on various factors, but can be appropriately adjusted, for example, by shortening the curing time when the curing temperature is increased and lengthening the curing time when the curing temperature is decreased. Curing can be performed in one step or in multiple steps (two or more steps). In the cured product, the nanodiamond particles (B) are dispersed in a matrix in which the continuous phase is an epoxy resin formed by polymerizing the alicyclic epoxy compound (A).

[0127] The glass transition temperature (Tg) of the cured product is preferably 120°C or higher. The glass transition temperature may be, for example, 200°C or lower, or 150°C or lower. When the glass transition temperature is 120°C or higher, the cured product has sufficient heat resistance. The glass transition temperature of the cured product can be measured by various thermal analyses (DSC (differential scanning calorimeter), TMA (thermomechanical analyzer), etc.) or dynamic viscoelasticity measurement, and more specifically, can be measured by the measurement method described in the Examples.

[0128] The curable epoxy composition and the cured product can be used in a variety of applications, such as an encapsulant for optical semiconductors (an encapsulant for an optical semiconductor element in an optical semiconductor device), an adhesive, an electrical insulating material, a laminate, a coating agent, an ink, a paint, a sealant, a resist, a composite material, a transparent substrate, a transparent sheet, a transparent film, an optical element, an optical lens, an optical member, stereolithography, electronic paper, a touch panel, a solar cell substrate, an optical waveguide, a light guide plate, and a holographic memory.

[0129] Each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. Each configuration and combination thereof in each embodiment is an example, and addition, omission, substitution, and other modifications of configurations are possible as appropriate within the scope of the present disclosure. Furthermore, each invention according to this disclosure is not limited by the embodiments or the following examples, but is limited only by the scope of the claims. [Example]

[0130] Hereinafter, one embodiment of the present disclosure will be described in more detail based on examples. It should be noted that Examples 3 to 10 should be read as Reference Examples 1 to 7.

[0131] Example 1 The surface-modified nanodiamond particles, curable epoxy composition, and cured product were prepared as follows.

[0132] (Preparation of surface-modified nanodiamond particles) First, the nanodiamond production process was carried out by detonation. In this process, the formed explosive with an electric detonator attached was placed inside a pressure-resistant container for detonation and the container was sealed. The container was made of iron and had a volume of 15 m. 3 The explosive used was a mixture of 0.50 kg of TNT and RDX. The mass ratio of TNT to RDX in this explosive (TNT / RDX) was 50 / 50. Next, an electric detonator was detonated to detonate the explosive inside the container (production of nanodiamonds by detonation method). The container and its interior were then allowed to cool for 24 hours at room temperature. After cooling, the crude nanodiamond product (including the aggregates of nanodiamond particles and soot produced by the detonation method) adhering to the inner wall of the container was scraped off with a spatula, and the crude nanodiamond product was recovered.

[0133] The crude nanodiamond product obtained by repeating the above-described production process multiple times was then subjected to an acid treatment process. Specifically, 200 g of the crude nanodiamond product was added to 6 L of 10% by mass hydrochloric acid to obtain a slurry, which was then heated under reflux at atmospheric pressure for 1 hour. The heating temperature in this acid treatment was 85 to 100°C. Next, after cooling, the solid matter (including nanodiamond aggregates and soot) was washed with water by decantation. The solid matter was repeatedly washed with water by decantation until the pH of the precipitated liquid reached 2 from the low pH side.

[0134] Next, an oxidation treatment step was carried out. Specifically, 6 L of 98% by mass sulfuric acid and 1 L of 69% by mass nitric acid were added to the precipitate liquid (containing nanodiamond aggregates) obtained through decantation after the acid treatment to form a slurry, and this slurry was then heat-treated for 48 hours under reflux at atmospheric pressure. The heating temperature in this oxidation treatment was 140 to 160°C. Next, after cooling, the solid content (including nanodiamond aggregates) was washed with water by decantation. The supernatant liquid was colored at the beginning of the washing, so the solid content was repeatedly washed with water by decantation until the supernatant liquid became visually transparent.

[0135] Next, the precipitate liquid (liquid containing nanodiamond aggregates) obtained after the above-mentioned water washing process was subjected to a drying process to obtain dry powder (nanodiamond aggregates). The drying method used in the drying process was evaporation to dryness using an evaporator.

[0136] Next, a surface modification process was performed. Specifically, 0.30 g of the nanodiamond powder obtained through the drying process described above was weighed into a 50 mL sample bottle. A solution containing the nanodiamond powder, 14 g of THF (solvent), and 1.2 g of 3-(trimethoxysilyl)propyl acrylate (Tokyo Chemical Industry Co., Ltd.) (silane coupling agent) was mixed and stirred for 10 minutes. Next, 34 g of zirconia beads (product name "YTZ", diameter 30 μm, Tosoh Corporation) were added to the solution. The mixed solution was then subjected to surface modification using an ultrasonic homogenizer (product name "UH-600S Ultrasonic Disperser", SMT Corporation). Specifically, the tip of the ultrasonic generator's transducer was inserted into a reaction vessel and immersed in the mixed solution. The mixed solution in the reaction vessel was subjected to ultrasonic treatment for 8 hours while the reaction vessel was cooled with ice water. During this treatment, the initially cloudy gray solution gradually darkened and became more transparent. This is thought to be due to the nanodiamond particles gradually being disintegrated (disintegrated) from the nanodiamond aggregates, and the silane coupling agent acting on the dissociated nanodiamond particles to bond them, resulting in the dispersion and stabilization of the surface-modified nanodiamond particles in the THF solvent. After 8 hours of surface modification treatment, the particle size D50 of the nanodiamond dispersion was measured using dynamic light scattering and found to be 15 nm. In this way, a dispersion of surface-modified nanodiamond particles was prepared.

[0137] The supernatant liquid collected after leaving the dispersion of the surface-modified nanodiamond particles overnight was dropped into a mixed solvent of 16 mL of toluene and 4 mL of hexane (total dropped amount: 10 mL), and the mixed solvent after dropping was centrifuged (centrifugal force 20,000 G, centrifugation time 10 minutes) to recover the settled solid matter (surface-modified nanodiamond particles of Example 1). THF was added to the recovered solid matter to prepare a THF solution of surface-modified nanodiamond particles (solid concentration 6.5 mass%), and the solution was subjected to ultrasonic treatment for 10 minutes using an ultrasonic treatment device (trade name "ASU-10", AS ONE Corporation). The particle size D50 of the surface-modified nanodiamond particles in the THF solution after this ultrasonic treatment was measured by dynamic light scattering and was found to be 12 nm.

[0138] (Preparation of Curable Epoxy Composition) The epoxy curing agent was prepared by uniformly mixing "RIKACID MH-700" (manufactured by New Japan Chemical Co., Ltd.), "U-CAT 18X" (manufactured by San-Apro Co., Ltd.), and ethylene glycol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in the proportions (unit: parts by mass) shown in Table 1 using a planetary stirrer (product name: "Awatori Rentaro AR-250" manufactured by Thinky Corporation) and degassing the mixture. The alicyclic epoxy compound (product name: "Celloxide 2021P" manufactured by Daicel Corporation), the surface-modified nanodiamond particles (solid content) from Example 1, and the epoxy curing agent in the proportions (unit: parts by mass) shown in Table 1 using a planetary stirrer (product name: "Awatori Rentaro AR-250" manufactured by Thinky Corporation) and degassing the mixture. A curable epoxy composition was prepared by uniformly mixing the epoxy curing agent and the surface-modified nanodiamond particles (solid content) from Example 1 in the proportions (unit: parts by mass) shown in Table 1 using a planetary stirrer (product name: "Awatori Rentaro AR-250" manufactured by Thinky Corporation).

[0139] (Preparation of cured product) The curable epoxy composition obtained above was filled into a mold and cured by heating in an oven at 120°C for 5 hours to produce a cured product.

[0140] Example 2 Curable epoxy compositions and cured products were prepared in the same manner as in Example 1, except that the amount of surface-modified nanodiamond particles was changed as shown in Table 1.

[0141] Example 3 The surface-modified nanodiamond particles, curable epoxy composition, and cured product were prepared as follows.

[0142] (Preparation of surface-modified nanodiamond particles) 10 mmol of polyalkylene glycol (trade name "UNIOX M-550" manufactured by NOF Corporation) was dissolved in 100 mL of THF, and 60 mmol of triethylamine was slowly added. 10 mmol of 3-(Trimethoxysilyl)propyl isocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.) was then added, and the mixture was allowed to react at 80°C for 48 hours with a reflux condenser attached. After the reaction was completed, the THF was removed by vacuum distillation using an evaporator. The mixture was then left to stand in a vacuum dryer at 110°C for 24 hours to completely remove the triethylamine, yielding a polyoxyalkylene chain-containing silane coupling agent ([(MeO)SiCHNHC(=O)-PEG], terminal: aliphatic hydrocarbon group, number average molecular weight as polyoxyalkylene: 550).

[0143] 0.30 g of the nanodiamond aggregate obtained through the drying process in Example 1 was weighed into a reaction vessel, and 15 cc of MEK, 4.0 g of the polyoxyalkylene chain-containing silane coupling agent, and 35 g of zirconia beads (trade name "YTZ", diameter 30 μm, manufactured by Tosoh Corporation) were added. After addition, the mixture was cooled in ice water and ultrasonicated for 15 hours using a homogenizer (trade name "UH-600S Ultrasonic Disperser", manufactured by SMT Corporation) with the tip of the ultrasonic disperser's vibrator immersed in the solution in the reaction vessel, causing the nanodiamond particles and polyoxyalkylene chain-containing silane coupling agent to react. Initially, the mixture was gray, but the particle size gradually decreased and the dispersion improved, eventually becoming a uniform, black liquid. This is thought to be because the nanodiamond particles are gradually disintegrated (disintegrated) from the nanodiamond aggregates, and the polyoxyalkylene chain-containing silane coupling agent acts on the dissociated nanodiamond particles to bond them, resulting in the dispersion and stabilization of the surface-modified nanodiamond particles in the MEK solvent. A 1:2 toluene / hexane mixture was added to the resulting dispersion, followed by centrifugation at 13,000 G for 15 minutes, the supernatant was removed, and the settled solids (surface-modified nanodiamond particles of Example 3) were recovered. 15 mL of THF was added to the resulting solids, which were then stirred in an ultrasonic cleaner to obtain a surface-modified nanodiamond dispersion. The particle size D50 of the surface-modified nanodiamond particles in the resulting surface-modified nanodiamond dispersion was 36 nm.

[0144] (Preparation of Curable Epoxy Composition and Cured Product) A curable epoxy composition and a cured product were prepared in the same manner as in Example 2, except that the solid content of the surface-modified nanodiamond particles of Example 3 obtained above was used instead of the surface-modified nanodiamond particles of Example 1.

[0145] Example 4 The surface-modified nanodiamond particles, curable epoxy composition, and cured product were prepared as follows.

[0146] (Preparation of surface-modified nanodiamond particles) A polyoxyalkylene chain-containing silane coupling agent ([(MeO)SiCHNHC(=O)-PPG], terminal: aliphatic hydrocarbon group, number average molecular weight as polyoxyalkylene: 700) was synthesized in the same manner as in Example 3, except that 10 mmol of polyalkylene glycol (trade name "UNILUBE MB-7", manufactured by NOF Corporation) was used instead of 10 mmol of polyalkylene glycol (trade name "UNIOX M-550", manufactured by NOF Corporation).

[0147] 0.30 g of the nanodiamond aggregate obtained through the drying process in Example 1 was weighed into a reaction vessel, and 15 cc of MEK, 4.0 g of the polyoxyalkylene chain-containing silane coupling agent, and 35 g of zirconia beads (trade name "YTZ", diameter 30 μm, manufactured by Tosoh Corporation) were added. After addition, the mixture was cooled in ice water and ultrasonicated for 15 hours using a homogenizer (trade name "UH-600S Ultrasonic Disperser", manufactured by SMT Corporation) with the tip of the ultrasonic disperser's vibrator immersed in the solution in the reaction vessel, causing the nanodiamond particles and polyoxyalkylene chain-containing silane coupling agent to react. Initially, the mixture was gray, but the particle size gradually decreased and the dispersion improved, eventually becoming a uniform, black liquid. This is thought to be because the nanodiamond particles are gradually dissociated (disintegrated) from the nanodiamond aggregates, and the polyoxyalkylene chain-containing silane coupling agent acts on the dissociated nanodiamond particles to bond them, and the surface-modified nanodiamond particles are dispersed and stabilized in the MEK solvent. After adding 8 times the amount of hexane to the resulting dispersion, the mixture was centrifuged at 13,000 G for 15 minutes, the supernatant was removed, and the settled solids (surface-modified nanodiamond particles of Example 4) were recovered. 15 mL of THF was added to the resulting solids and stirred in an ultrasonic cleaner to obtain a surface-modified nanodiamond dispersion. The particle size D50 of the surface-modified nanodiamond particles in the resulting surface-modified nanodiamond dispersion was 40 nm.

[0148] (Preparation of Curable Epoxy Composition and Cured Product) A curable epoxy composition and a cured product were prepared in the same manner as in Example 3, except that the solid content of the surface-modified nanodiamond particles of Example 4 obtained above was used instead of the surface-modified nanodiamond particles of Example 3.

[0149] Example 5 The surface-modified nanodiamond particles, curable epoxy composition, and cured product were prepared as follows.

[0150] (Preparation of surface-modified nanodiamond particles) A polyoxyalkylene chain-containing silane coupling agent ([(MeO)SiCHNHC(=O)-PPG-PEG], terminal: aliphatic hydrocarbon group, number average molecular weight as polyoxyalkylene: 500) was synthesized in the same manner as in Example 3, except that 10 mmol of polyalkylene glycol (trade name "Uniloop 50MB-5", manufactured by NOF Corporation) was used instead of 10 mmol of polyalkylene glycol (trade name "Uniox M-550", manufactured by NOF Corporation).

[0151] 0.30 g of the nanodiamond aggregate obtained through the drying process in Example 1 was weighed into a reaction vessel, and 15 cc of MEK, 4.0 g of the polyoxyalkylene chain-containing silane coupling agent, and 35 g of zirconia beads (trade name "YTZ", diameter 30 μm, manufactured by Tosoh Corporation) were added. After addition, the mixture was cooled in ice water and ultrasonicated for 15 hours using a homogenizer (trade name "UH-600S Ultrasonic Disperser", manufactured by SMT Corporation) with the tip of the ultrasonic disperser's vibrator immersed in the solution in the reaction vessel, causing the nanodiamond particles and polyoxyalkylene chain-containing silane coupling agent to react. Initially, the mixture was gray, but the particle size gradually decreased and the dispersion improved, eventually becoming a uniform, black liquid. This is thought to be because the nanodiamond particles are gradually dissociated (disintegrated) from the nanodiamond aggregates, and the polyoxyalkylene chain-containing silane coupling agent acts on the dissociated nanodiamond particles to bond them, and the surface-modified nanodiamond particles are dispersed and stabilized in the MEK solvent. After adding one volume of hexane to the resulting dispersion, the mixture was centrifuged at 13,000 G for 15 minutes, the supernatant was removed, and the settled solids (surface-modified nanodiamond particles of Example 5) were recovered. 15 mL of THF was added to the resulting solids and stirred in an ultrasonic cleaner to obtain a surface-modified nanodiamond dispersion. The particle size D50 of the surface-modified nanodiamond particles in the resulting surface-modified nanodiamond dispersion was 45 nm.

[0152] (Preparation of Curable Epoxy Composition and Cured Product) A curable epoxy composition and a cured product were prepared in the same manner as in Example 3, except that the solid content of the surface-modified nanodiamond particles of Example 5 obtained above was used instead of the surface-modified nanodiamond particles of Example 3.

[0153] Comparative Example 1 A curable epoxy composition and a cured product were prepared in the same manner as in Example 2, except that a bisphenol A epoxy resin (trade name "YD-128", manufactured by Nippon Steel Chemical & Material Co., Ltd.) was used instead of the alicyclic epoxy compound.

[0154] Comparative Example 2 A curable epoxy composition and a cured product were prepared in the same manner as in Comparative Example 1, except that the surface-modified nanodiamond particles were not added.

[0155] Comparative Example 3 A curable epoxy composition and a cured product were prepared in the same manner as in Example 1, except that the surface-modified nanodiamond particles were not added.

[0156] Comparative Example 4 A curable epoxy composition and a cured product were prepared in the same manner as in Example 1, except that fullerene was used instead of the surface-modified nanodiamond particles.

[0157] Example 6 Curable epoxy compositions and cured products were prepared as follows.

[0158] (Preparation of Curable Epoxy Composition) The product name "Celloxide 2021P" (manufactured by Daicel Corporation), the surface-modified nanodiamond particles (solid content) from Example 1, and the product name "Sanaid SI-100L" (manufactured by Sanshin Chemical Industry Co., Ltd.) were mixed uniformly in the proportions (unit: parts by mass) shown in Table 2 using a planetary stirring device (product name "Awatori Rentaro AR-250", manufactured by Thinky Corporation), and then degassed to prepare a curable epoxy composition.

[0159] (Preparation of cured product) The curable epoxy composition obtained above was filled into a mold and cured by heating in an oven at 80°C for 2 hours and then at 140°C for 2 hours to produce a cured product.

[0160] Example 7 Curable epoxy compositions and cured products were prepared in the same manner as in Example 6, except that the amount of surface-modified nanodiamond particles was changed as shown in Table 2.

[0161] Example 8 A curable epoxy composition and a cured product were prepared in the same manner as in Example 7, except that the surface-modified nanodiamond particles of Example 3 were used instead of the surface-modified nanodiamond particles of Example 1.

[0162] Example 9 A curable epoxy composition and a cured product were prepared in the same manner as in Example 7, except that the surface-modified nanodiamond particles of Example 4 were used instead of the surface-modified nanodiamond particles of Example 1.

[0163] Example 10 A curable epoxy composition and a cured product were prepared in the same manner as in Example 7, except that the surface-modified nanodiamond particles of Example 5 were used instead of the surface-modified nanodiamond particles of Example 1.

[0164] Comparative Example 5 A curable epoxy composition and a cured product were prepared in the same manner as in Example 7, except that a bisphenol A epoxy resin (trade name "YD-128", manufactured by Nippon Steel Chemical & Material Co., Ltd.) was used instead of the alicyclic epoxy compound.

[0165] Comparative Example 6 A curable epoxy composition and a cured product were prepared in the same manner as in Comparative Example 5, except that the surface-modified nanodiamond particles were not added.

[0166] Comparative Example 7 A curable epoxy composition and a cured product were prepared in the same manner as in Example 6, except that the surface-modified nanodiamond particles were not added.

[0167] Comparative Example 8 A curable epoxy composition and a cured product were prepared in the same manner as in Example 6, except that fullerene was used instead of the surface-modified nanodiamond particles.

[0168] <Evaluation> The surface-modified nanodiamond particles, curable epoxy compositions, and cured products obtained in the examples and comparative examples were subjected to the following evaluation tests.

[0169] (D50 particle size in nanodiamond dispersion) The median diameter (particle size D50) of the nanodiamond particles in the nanodiamond dispersion is a volume-based value measured from the particle size distribution of the nanodiamonds obtained by dynamic light scattering. Specifically, the particle size distribution of the nanodiamonds was measured by dynamic light scattering (non-contact backscattering) using a Malvern device (trade name "Zetasizer Nano ZS").

[0170] (Average dispersed particle size in the cured product) The average dispersed particle diameter of nanodiamond particles in the cured product was calculated by observation with a transmission electron microscope (TEM). Specifically, the cured product was observed with a transmission electron microscope (trade name "JEM-1400Plus", manufactured by JEOL Ltd.) for 300 nanodiamond particles, and the longest linear distance between the ends of the nanodiamond particles (in the case of aggregates, the aggregates of nanodiamond particles) was measured as the dispersed particle diameter, and the average value was calculated. The obtained average value was then used as the average dispersed particle diameter in the cured product, and it was determined that the average dispersed particle diameter in the curable epoxy composition was equal to or less than the average dispersed particle diameter in the cured product.

[0171] (glass transition temperature) The glass transition temperature of the cured product was measured using a differential scanning calorimeter (product name "Q2000", manufactured by TA Instruments) under conditions of a temperature rise rate of 20°C / min and a measurement temperature range of -50 to 250°C under a nitrogen gas flow after pre-treatment (heating from -50°C to 250°C at a heating rate of 20°C / min, followed by cooling from 250°C to -5°C at a rate of -20°C / min). The inflection point of the obtained temperature dimensional change curve was then taken as the glass transition temperature.

[0172] [Table 1]

[0173] [Table 2]

[0174] As can be seen from Tables 1 and 2, the cured product of the alicyclic epoxy compound containing nanodiamond particles has a higher glass transition temperature (Example) than the product without nanodiamond particles (Comparative Examples 3 and 7), indicating improved heat resistance. Furthermore, when fullerenes were used instead of nanodiamond particles, the glass transition temperature of the cured product did not improve (Comparative Examples 4 and 8). Furthermore, when bisphenol A epoxy resin, an epoxy compound with an aromatic ring, was used instead of the alicyclic epoxy compound, the increase in the glass transition temperature of the cured product was small, and heat resistance did not improve significantly (Comparative Examples 1, 2, 5, and 6).

[0175] The components used in the examples and comparative examples are as follows: (epoxy compounds) Celloxide 2021P: Product name "Celloxide 2021P" [3,4-epoxycyclohexylmethyl (3',4'-epoxy) cyclohexanecarboxylate], manufactured by Daicel Corporation YD-128: Product name "YD-128" [bisphenol A type epoxy resin], manufactured by Nippon Steel Chemical & Material Co., Ltd. (epoxy hardener) MH-700: Product name "Rikacid MH-700" [hardener] [4-methylhexahydrophthalic anhydride / hexahydrophthalic anhydride = 70 / 30], manufactured by New Japan Chemical Co., Ltd. U-CAT 18X: Product name "U-CAT 18X" [curing accelerator], manufactured by San-Apro Co., Ltd. Ethylene glycol: Fujifilm Wako Pure Chemical Industries, Ltd. (curing catalyst) San-Aid SI-100L: Product name "San-Aid SI-100L", manufactured by Sanshin Chemical Industry Co., Ltd.

[0176] Variations of the invention according to the present disclosure are described below. [Appendix 1] A curable epoxy composition comprising an alicyclic epoxy compound (A) having an alicyclic structure and an epoxy group in the molecule, nanodiamond particles (B), a curing agent (C) and a curing accelerator (D), or a curing catalyst (E). [Appendix 2] A curable epoxy composition according to Appendix 1, in which nanodiamond particles (B) are dispersed in a matrix of an alicyclic epoxy compound (A). [Appendix 3] A curable epoxy composition according to Appendix 2, wherein the average primary particle diameter of the nanodiamond particles (B) in the curable epoxy composition is 10 nm or less (preferably 8 nm or less, more preferably 7 nm or less). [Appendix 4] A curable epoxy composition according to Appendix 2 or 3, wherein the average dispersed particle diameter of the nanodiamond particles (B) in the curable epoxy composition is 100 nm or less (preferably 50 nm or less, more preferably 40 nm or less). [Appendix 5] A curable epoxy composition comprising an epoxy compound (A') having an epoxy group in the molecule and nanodiamond particles (B) dispersed in a matrix in which the epoxy compound (A') is the continuous phase, wherein the average dispersed particle size of the nanodiamond particles (B) in the curable epoxy composition is 100 nm or less (preferably 50 nm or less, more preferably 40 nm or less). [Appendix 6] A curable epoxy composition according to Appendix 5, wherein the average primary particle diameter of the nanodiamond particles (B) in the curable epoxy composition is 10 nm or less (preferably 8 nm or less, more preferably 7 nm or less). [Appendix 7] A curable epoxy composition according to Appendix 5 or 6, wherein the epoxy compound (A') comprises an alicyclic epoxy compound (A) having an alicyclic structure and an epoxy group in the molecule. [Appendix 8] A curable epoxy composition according to any one of Appendices 1 to 7, wherein the nanodiamond particles (B) comprise surface-modified nanodiamond particles.

[0177] [Appendix 9] A curable epoxy composition according to Appendix 8, wherein the surface modifying group that modifies the surface of the nanodiamond particles has a group represented by the following formula (1): -X(-R 2-X) n -R 1 (1) [In formula (1), X represents a linking group containing a heteroatom in the main chain. R 1 represents a substituted or unsubstituted monovalent organic group, and R 2 represents a substituted or unsubstituted divalent organic group, and R 1 and R 2 The atom bonded to X in formula (1) is a carbon atom. n represents an integer of 0 or more, and when n is an integer of 1 or more, the multiple Xs in formula (1) may be the same or different.] [Appendix 10] The curable epoxy composition according to Appendix 9, wherein in the formula (1), X is a linking group containing one or more heteroatoms selected from the group consisting of nitrogen atoms, oxygen atoms, and sulfur atoms in the main chain. [Appendix 11] The curable epoxy composition according to Appendix 10, wherein in the formula (1), X is -NH-, -O-, -OC(=O)-, -C(=O)-O-, -NH-C(=O)-, -C(=O)-NH-, -NH-C(=O)-O-, -OC(=O)-NH-, -S-, a divalent group in which two or more of these bonds are bonded, or a group in which one or more of these bonds are bonded to -C(=O)-. [Appendix 12] In the formula (1), the ratio of R to the total amount of X 1 and R 2 12. The curable epoxy composition according to any one of Appendices 9 to 11, wherein the total number (molar ratio) of carbon atoms therein is 1 to 8 (preferably 1 to 3, more preferably 1 to 2). [Appendix 13] In the formula (1), R 1 13. The curable epoxy composition according to any one of claims 9 to 12, wherein represents a substituted or unsubstituted monovalent hydrocarbon group. [Appendix 14] The monovalent hydrocarbon group is C 1-8 Hydrocarbon group (preferably C 1-5 Hydrocarbon groups, more preferably C 2-4 14. The curable epoxy composition according to claim 13, wherein the aryl group is a hydrocarbon group. [Appendix 15] The curable epoxy composition according to Appendices 13 and 14, wherein the monovalent hydrocarbon group is a monovalent aliphatic hydrocarbon group (preferably a linear or branched alkylene group, or a linear or branched alkenylene group, more preferably a linear or branched alkylene group). [Appendix 16] In the formula (1), R 2 16. The curable epoxy composition according to any one of claims 9 to 15, wherein represents a substituted or unsubstituted divalent hydrocarbon group. [Appendix 17] The divalent hydrocarbon group is C 1-8 Hydrocarbon group (preferably C 1-5 Hydrocarbon groups, more preferably C 2-4 17. The curable epoxy composition according to claim 16, wherein the aryl group is a hydrocarbon group. [Appendix 18] The curable epoxy composition according to Appendices 16 and 17, wherein the divalent hydrocarbon group is a divalent aliphatic hydrocarbon group (preferably a linear or branched alkylene group, or a linear or branched alkenylene group, more preferably a linear or branched alkylene group). [Appendix 19] The group represented by the formula (1) is an alkoxy group, an alkenyloxy group, an acyloxy group, an alkyl-substituted amino group, or (-R 2 -X) n is a polyoxyalkylene chain, and (-R 2 -X) n 19. The curable epoxy composition according to any one of claims 9 to 18, wherein is one or more groups selected from the group consisting of groups which are polyglyceryl chains.

[0178] [Appendix 20] The group represented by the formula (1) is (-R 2 -X) n 19. The curable epoxy composition according to claim 18, wherein [Appendix 21] The curable epoxy composition according to Appendix 20, wherein X outside the parentheses in formula (1) is —NH—C(═O)—O—. [Appendix 22] The curable epoxy composition according to Appendix 20 or 21, wherein the polyoxyalkylene chain constituting the polyoxyalkylene chain is a polyethylene glycol chain, a polypropylene glycol chain, a polytetramethylene glycol chain, a polybutylene glycol chain, or a polyoxyalkylene chain in which two or more of these are bonded. [Appendix 23] The curable epoxy composition according to any one of Appendices 20 to 22, wherein the polyoxyalkylene chain has a number average molecular weight as polyoxyalkylene of 100 to 10,000 (preferably 200 to 5,000, more preferably 300 to 4,000, even more preferably 400 to 2,500, and particularly preferably 500 to 3,000). [Appendix 24] The curable epoxy composition according to any one of Appendices 20 to 23, wherein the average degree of polymerization (number average degree of polymerization) of the oxyalkylene groups in the polyoxyalkylene chain is 2 to 50 (preferably 4 to 45, more preferably 6 to 40).

[0179] [Appendix 25] The group represented by the formula (1) is (-R 2 -X) n 20. The curable epoxy composition of claim 19, wherein [Appendix 26] (-R 2 -X) n is a polyglycerin chain represented by the following formula (A): -(C3H6O2) p -(C3H5O2R a ) q - (A) [In formula (A), p and q each represent the average degree of polymerization of the repeating units in the parentheses, where p is a value of 0 or more, q is a value exceeding 0, and p+q represents an integer of 1 or more. a represents a monovalent organic group. [Appendix 27] The curable epoxy composition according to Appendix 26, wherein, in the formula (A), p+q is 1 to 100 (preferably 2 to 40, more preferably 3 to 30). [Appendix 28] The curable epoxy composition according to appendix 26 or 27, wherein in formula (A), [q / (p+q)] is 0.6 or more (preferably 0.8 to 1.0).

[0180] [Appendix 29] The curable epoxy composition according to any one of Appendices 9 to 28, wherein the group represented by formula (1) is a group represented by the following formula (2): -R 3 -X(-R 2 -X) n -R 1 (2) [In formula (2), R 3 represents a substituted or unsubstituted divalent organic group. The rest are the same as those in the formula (1). [Appendix 30] In the formula (2), R 1 , R 2 , and R 3 29. The curable epoxy composition according to claim 29, wherein the total number (molar ratio) of carbon atoms therein is 1 to 8 (preferably 1 to 3, more preferably 1 to 2). [Appendix 31] In the formula (2), R 3 31. The curable epoxy composition according to claim 29 or 30, wherein represents a substituted or unsubstituted divalent hydrocarbon group. [Appendix 32] The divalent hydrocarbon group is C 1-20 Hydrocarbon group (preferably C 1-10 Hydrocarbon groups, more preferably C 1-5 32. The curable epoxy composition according to claim 31, wherein the aryl group is a hydrocarbon group. [Appendix 33] R in the above formula (2) 3 A curable epoxy composition according to any one of claims 29 to 32, wherein the bond extending to the left from is bonded to the nanodiamond particle via a silicon atom.

[0181] [Appendix 34] The curable epoxy composition according to Appendix 33, wherein the group represented by formula (2) is a group represented by the following formula (3): -O-Si-R 3 -X(-R 2 -X) n -R 1 (3) [In formula (3), the bond extending to the left from the oxygen atom is bonded to the nanodiamond particle. The silicon atom in formula (3) is bonded to the oxygen atom and R 3 In addition, it bonds to a hydrogen atom, an aliphatic hydrocarbon group having 1 to 3 carbon atoms, a nanodiamond particle, or a silicon atom via an oxygen atom.] [Appendix 35] A curable epoxy composition according to any one of Appendices 8 to 34, wherein the surface-modified nanodiamond has zirconia attached thereto. [Appendix 36] The curable epoxy composition according to Appendix 35, wherein the content of zirconia in the curable epoxy composition is 0.001 to 10 mass% (preferably 0.01 to 1.0 mass%, more preferably 0.05 to 0.5 mass%) relative to the total amount of the curable epoxy composition. [Appendix 37] A curable epoxy composition according to any one of Appendices 1 to 36, wherein the content of nanodiamond particles (B) in the curable epoxy composition is 0.1 mass ppm to 10 mass % relative to the total amount of the curable epoxy composition. [Appendix 38] A curable epoxy composition according to any one of Appendices 1 to 4 and 7 to 37, wherein the content of nanodiamond particles (B) in the curable epoxy composition is 0.01 to 50 parts by mass (preferably 0.05 to 40 parts by mass, more preferably 0.1 to 10 parts by mass) per 100 parts by mass of the total amount of alicyclic epoxy compound (A).

[0182] [Appendix 39] The curable epoxy composition according to any one of Appendices 1 to 4 and 7 to 38, wherein the alicyclic epoxy compound (A) has two or more epoxy groups in the molecule. [Appendix 40] The alicyclic epoxy compound (A) is a curable composition according to any one of Appendices 1 to 4 and 7 to 39, which comprises one or more compounds selected from the group consisting of: (I) a compound having an epoxy group composed of two adjacent carbon atoms and an oxygen atom that constitute an alicyclic ring in the molecule; (II) a compound in which an epoxy group is directly bonded to an alicyclic ring via a single bond; and (III) a compound having an alicyclic ring and a glycidyl ether group in the molecule. [Appendix 41] The curable epoxy composition according to Appendix 40, wherein the alicyclic epoxy compound (A) comprises (I) a compound having an epoxy group composed of two adjacent carbon atoms and an oxygen atom that constitute an alicyclic ring in the molecule, and / or (II) a compound having an epoxy group directly bonded to the alicyclic ring via a single bond. [Appendix 42] The curable epoxy composition according to any one of Appendices 1 to 4 and 7 to 41, wherein the alicyclic epoxy compound (A) comprises a compound having a cyclohexene oxide group. [Appendix 43] The curable epoxy composition according to any one of Appendices 1 to 4 and 7 to 42, wherein the content of the alicyclic epoxy compound (A) in the curable epoxy composition is 10% by mass or more (preferably 20% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more), relative to the total amount of the curable epoxy composition. [Appendix 44] The curable epoxy composition according to any one of Appendices 1 to 4 and 7 to 43, wherein the content of the alicyclic epoxy compound (A) in the cationic curable compounds in the curable epoxy composition is 50% by mass or more (preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more), relative to the total amount of all cationic curable compounds in the curable epoxy composition. [Appendix 45] The curable epoxy composition according to any one of Appendices 1 to 4 and 7 to 44, wherein the content of the alicyclic epoxy compound (A) in 100% by mass of compounds having an epoxy group contained in the curable epoxy composition is 50% by mass or more (preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 90% by mass or more, particularly preferably 95% by mass or more).

[0183] [Appendix 46] A cured product of the curable epoxy composition according to any one of Appendices 1 to 45. [Appendix 47] The cured product according to Appendix 46, having a glass transition temperature of 120°C or higher. [Appendix 48] A cured product according to appendix 46 or 47, having a glass transition temperature of 200°C or lower (preferably 150°C or lower). [Appendix 49] A curable epoxy composition according to any one of Appendices 46 to 48, wherein the average primary particle diameter of the nanodiamond particles (B) in the cured product is 10 nm or less (preferably 8 nm or less, more preferably 7 nm or less). [Appendix 50] An optical member comprising the cured product according to any one of Appendices 46 to 49.

[0184] [Appendix 51] A sealant comprising the curable epoxy composition according to any one of Appendices 1 to 44. [Appendix 52] An adhesive comprising the curable epoxy composition according to any one of Appendices 1 to 44. [Appendix 53] A coating agent comprising the curable epoxy composition according to any one of Appendices 1 to 44.

Claims

1. The composition comprises an alicyclic epoxy compound (A) having an alicyclic structure and an epoxy group in the molecule, nanodiamond particles (B), a curing agent (C) and a curing accelerator (D), or a curing catalyst (E), The nanodiamond particles (B) include surface-modified nanodiamond particles; The surface modifying group that modifies the surface of the nanodiamond particle has a group represented by the following formula (1): The content of the nanodiamond particles (B) is 0.01 to 50 parts by mass per 100 parts by mass of the total amount of the alicyclic epoxy compound (A), The curable epoxy composition further comprises a compound having a hydroxy group. -X(-R ２ -X) ｎ -R １ (1) [In formula (1), X represents -O-, -O-C(=O)-, -C(=O)-O-, -S-, a divalent group formed by combining two or more of these bonds, or a group formed by combining one or more of these bonds with -C(=O)-. R １ represents a substituted or unsubstituted monovalent organic group, and R ２ represents a substituted or unsubstituted divalent organic group, and R １ and R ２ The atom bonded to X in formula (1) is a carbon atom. n represents an integer of 0 or more, and when n is an integer of 1 or more, the multiple Xs in formula (1) may be the same or different.]

2. 2. The curable epoxy composition according to claim 1, wherein the nanodiamond particles (B) are dispersed in a matrix having the alicyclic epoxy compound (A) as a continuous phase.

3. The curable epoxy composition according to claim 2, wherein the average primary particle diameter of the nanodiamond particles (B) in the curable epoxy composition is 10 nm or less.

4. The curable epoxy composition according to claim 2 or 3, wherein the average dispersed particle size of the nanodiamond particles (B) in the curable epoxy composition is 100 nm or less.

5. In the formula (1), the ratio of R to the total amount of X １ and R ２ The curable epoxy composition according to any one of claims 1 to 4, wherein the total amount (molar ratio) of carbon atoms in the

6. In the formula (1), R １ represents a substituted or unsubstituted monovalent hydrocarbon group, R ２ The curable epoxy composition according to any one of claims 1 to 5, wherein represents a substituted or unsubstituted divalent hydrocarbon group.

7. The curable epoxy composition according to any one of claims 1 to 6, wherein the formula (1) is a group represented by the following formula (2): -R ３ -X(-R ２ -X) ｎ -R １ (2) [In formula (2), R ３ represents a substituted or unsubstituted divalent organic group. The rest are the same as those in formula (1).

8. In the formula (2), the ratio of R to the total amount of X １ , R ２ , and R ３ The curable epoxy composition of claim 7, wherein the total amount (molar ratio) of carbon atoms in the

9. In the formula (2), R ３ The curable epoxy composition according to claim 7 or 8, wherein represents a substituted or unsubstituted divalent hydrocarbon group.

10. R in the formula (2) ３ The curable epoxy composition according to any one of claims 7 to 9, wherein the bond extending to the left from is bonded to the nanodiamond particle via a silicon atom.

11. The curable epoxy composition according to any one of claims 1 to 10, wherein the alicyclic epoxy compound (A) has two or more epoxy groups in the molecule.

12. The curable epoxy composition according to any one of claims 1 to 11, wherein the alicyclic epoxy compound (A) comprises (I) a compound having an epoxy group composed of two adjacent carbon atoms and an oxygen atom that constitute an alicyclic ring in the molecule, and / or (II) a compound having an epoxy group directly bonded to an alicyclic ring via a single bond.

13. The curable epoxy composition according to any one of claims 1 to 12, wherein the alicyclic epoxy compound (A) comprises a compound having a cyclohexene oxide group.

14. A cured product of the curable epoxy composition according to any one of claims 1 to 13.

15. The cured product according to claim 14, which has a glass transition temperature of 120°C or higher.

16. An optical component comprising the cured product according to claim 14 or 15.

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