Base generator, curable resin composition, cured product thereof, and printed wiring board

Abstract

Provided are a base generator, a curable resin composition, and a printed wiring board, which have excellent storage stability in a one-component form and exhibit high catalytic activity at a desired curing temperature to cause a curing reaction in a short time. A base generator represented by the following formula (a), which comprises an imidazolium cation and an anion residue of an organic acid or an inorganic acid. [Formula 1] TIFF0007819427000026.tif22170In formula (a), A represents a divalent group of 1 to 8 carbon atoms which may contain a heteroatom, R1 to R4 each independently represent a hydrogen atom, an alkyl group of 1 to 8 carbon atoms which may have a substituent, an aryl group of 6 to 20 carbon atoms which may have a substituent, or an alkylaryl group of 7 to 20 carbon atoms which may have a substituent, and R1 and R2, R2 and R3, and R3 and R4 may each bond to form a ring structure. R5 to R9 each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms which may have a substituent, a halogen atom, a hydroxyl group, an alkoxy group, a mercapto group, a sulfide group, a silyl group, a silanol group, a nitro group, a nitroso group, a cyano group, a sulfino group, a sulfo group, a sulfonato group, a phosphino group, a phosphinyl group, a phosphono group, a phosphonato group, an amino group, or an ammonio group, and R5 and R6, R6 and R7, R7 and R8, and R8 and R9 may each bond to form a ring structure. - is the anionic residue of an organic or inorganic acid.

Description

[Technical Field]

[0001] The present invention relates to a base generator, a curable resin composition containing the base generator, a cured product thereof, and a printed wiring board. [Background technology]

[0002] Conventionally, curing accelerators for thermosetting resins, particularly those for epoxy resins, include phosphorus-based or pyridine-based curing accelerators. Phosphorus-based curing accelerators are known to have high curing power and to produce cured products with high electrical reliability. Examples of latent curing accelerators among phosphorus-based curing accelerators include tetraphenylphosphonium tetra(4-methylphenyl)borate (Patent Document 1), (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, butyltriphenylphosphonium thiocyanate (Patent Document 2), tetrabutylphosphonium 2-pyrrolidone-5-carboxylate, tetrabutylphosphonium 2-pyrrolidone-5-carboxylate (Patent Document 3), quaternary phosphonium salts of divalent or higher carboxylic acids (Patent Document 4), phosphonium carboxylate (Patent Document 5), quaternary phosphonium compounds (Patent Document 6), phosphonium thiocyanate (Patent Document 7), and 1,2-bis(diphenylphosphino)acetylene (Patent Document 8). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent No. 3638258 [Patent Document 2] International Publication No. 2010 / 087526 [Patent Document 3] International Publication No. 2009 / 014270 [Patent Document 4] Japanese Patent Publication No. 3-20065 [Patent Document 5] Japanese Patent Application Publication No. 2016-113475 [Patent Document 6] Japanese Patent Application Publication No. 11-158251 [Patent Document 7] Japanese Patent Publication No. 2010-209150 [Patent Document 8] Japanese Patent Application Publication No. 2015-172136 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional curing accelerators do not react at room temperature, but are insufficient in terms of potential to accelerate curing in response to external stimuli such as heating. An object of the present invention is to provide a base generator and a curable resin composition which have excellent storage stability in a one-part form and which exhibit high catalytic activity at a desired curing temperature to initiate a curing reaction in a short time. [Means for solving the problem]

[0005] That is, the present invention relates to the following [1] to

[16] . In this application, "(Numerical value 1) to (Numerical value 2)" indicates that the upper and lower limit values ​​are included. [1] A base generator represented by the following formula (a), which comprises a pyridinium cation and an anion residue of an organic acid or an inorganic acid:

[0006] [ka]

[0007] In formula (a), A represents a divalent group having 1 to 8 carbon atoms which may contain a heteroatom; R1 to R4 are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms which may have a substituent, an aryl group having 6 to 20 carbon atoms which may have a substituent, or an alkylaryl group having 7 to 20 carbon atoms which may have a substituent; R1 and R2, R2 and R3, and R3 and R4 may each bond to form a ring structure; R5 to R9 are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms which may have a substituent, a halogen atom, a hydroxyl group, an alkoxy group, a mercapto group, a sulfide group, a silyl group, a silanol group, a nitro group, a nitroso group, a cyano group, a sulfino group, a sulfo group, a sulfonato group, a phosphino group, a phosphinyl group, a phosphono group, a phosphonato group, an amino group, or an ammonio group; R5 and R6, R6 and R7, R7 and R8, and R8 and R9 may each bond to form a ring structure; X - is the anionic residue of an organic or inorganic acid. [2] The base generator according to the above item [1], wherein in the formula (a), R1 is a methyl group or a phenyl group, R2 is a methyl group or a benzyl group, and R3 and R4 are hydrogen atoms. [3] The base generator according to item [1] or [2] above, wherein A in formula (a) is an unsubstituted divalent hydrocarbon group having 1 to 8 carbon atoms, or a divalent group having 1 to 8 carbon atoms containing a carbonyl group, an ether group, an ester group, an amide group, or a sulfide group. [4] The anionic residue X in the formula (a) -

[0023] The base generator according to any one of the preceding items [1] to [3], wherein contains a halogen atom, a boron atom, or a silicon atom. [5] The anionic residue X in the formula (a) - The base generator according to any one of the above items [1] to [3], wherein the base generator is represented by the following formula (b-1):

[0008] [ka]

[0009] In formula (b-1), R 10 ~R 13 each independently represents a linear alkyl group having 1 to 16 carbon atoms, a branched alkyl group having 3 to 16 carbon atoms, or a substituted or unsubstituted aromatic ring having 6 to 16 carbon atoms. [6] R in the formula (b-1) 10 ~R 13 The base generator according to the above item [5], wherein each of [7] The anionic residue X in the formula (a) - The base generator according to any one of the above items [1] to [3], wherein the base generator is represented by the following formula (b-2):

[0010] [ka]

[0011] In formula (b-2), Y1 and Y2 are organic groups and may be the same or different from each other. Z1 represents an organic group having a substituted or unsubstituted aromatic ring or heterocyclic ring, or a substituted or unsubstituted aliphatic group. [8] The anionic residue X in the formula (a) - The base generator according to any one of the above items [1] to [3], wherein the base generator is represented by the following formula (b-3) or the following formula (b-4):

[0012] [ka]

[0013] [ka]

[0014] [9] A curable resin composition containing the base generator according to any one of items [1] to [8] above.

[10] The curable resin composition according to the above item [9], further comprising an epoxy resin.

[11] The curable resin composition according to item [9] or

[10] , further comprising a curing agent.

[12] The curable resin composition according to any one of items [9] to

[11] , further comprising at least one selected from the group consisting of maleimide compounds, polyphenylene ether compounds, compounds having an ethylenically unsaturated bond, cyanate compounds, polybutadiene and modified products thereof, polystyrene and modified products thereof, and polyethylene and modified products thereof.

[13] The curable resin composition according to any one of items [9] to

[12] , further comprising at least one selected from the group consisting of a thermal polymerization initiator, a photopolymerization initiator, an anionic curing accelerator, and a cationic curing accelerator.

[14] The curable resin composition according to any one of items [9] to

[13] above, which is used for a semiconductor encapsulant, an adhesive, an adhesive film, a prepreg, an interlayer insulating material, or a thermally conductive and heat-dissipating material.

[15] A cured product of the curable resin composition according to any one of the preceding items [9] to

[14] .

[16] A printed wiring board having the cured product according to the preceding item

[15] . [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a base generator and a curable resin composition which have excellent storage stability in a one-part form and which exhibit high catalytic activity at a desired curing temperature to initiate a curing reaction in a short time. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a 1H-NMR chart of Synthesis Example 1. [Figure 2] 1 is a 1H-NMR chart of Synthesis Example 2. [Figure 3] 1 is a 1H-NMR chart of Synthesis Example 3. [Figure 4] 1 is a 1H-NMR chart of Comparative Synthesis Example 1. [Figure 5] 1 is a 1H-NMR chart of Synthesis Example 4. [Figure 6] 1 is a 1H-NMR chart of Synthesis Example 5. DETAILED DESCRIPTION OF THE INVENTION

[0017] The base generator of the present invention comprises an imidazolium cation and an anion residue of an organic or inorganic acid, and is represented by the following formula (a): The base generator is a compound that generates a base upon irradiation with ultraviolet or visible light or upon heating.

[0018] [ka]

[0019] In the above formula (a), A represents a divalent group of 1 to 8 carbon atoms which may contain a heteroatom. A is preferably an unsubstituted divalent hydrocarbon group of 1 to 8 carbon atoms, or a divalent group of 1 to 8 carbon atoms which contains a carbonyl group, an ether group, an ester group, an amide group, or a sulfide group. A more preferably has 1 to 5 carbon atoms, particularly preferably 1 to 3 carbon atoms, and most preferably A is a methylene group. Examples of heteroatoms include an oxygen atom, a sulfur atom, and a nitrogen atom.

[0020] In the above formula (a), R1 to R4 are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms which may have a substituent, an aryl group having 6 to 20 carbon atoms which may have a substituent, or an alkylaryl group having 7 to 20 carbon atoms which may have a substituent, and R1 and R2, R2 and R3, and R3 and R4 may each be bonded to form a ring structure. R1 is preferably a methyl group or a phenyl group, R2 is preferably a methyl group or a benzyl group, and R3 and R4 are preferably hydrogen atoms.

[0021] In the above formula (a), R5 to R9 each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms which may have a substituent, a halogen atom, a hydroxyl group, an alkoxy group, a mercapto group, a sulfide group, a silyl group, a silanol group, a nitro group, a nitroso group, a cyano group, a sulfino group, a sulfo group, a sulfonato group, a phosphino group, a phosphinyl group, a phosphono group, a phosphonato group, an amino group, or an ammonio group, and R5 and R6, R6 and R7, R7 and R8, and R8 and R9 may each bond to form a ring structure.

[0022] The anionic residue X in the above formula (a) - Preferably, contains a halogen atom, a boron atom, or a silicon atom. The anionic residue X in the above formula (a) - is more preferably represented by either formula (b-1) or (b-2) below.

[0023] [ka]

[0024] In the above formula (b-1), R 10 ~R 13 each independently represents a linear alkyl group having 1 to 16 carbon atoms or a branched alkyl group having 3 to 16 carbon atoms, or a substituted or unsubstituted aromatic ring having 6 to 16 carbon atoms, preferably a substituted or unsubstituted aromatic ring having 6 to 16 carbon atoms.

[0025] [ka]

[0026] In the formula (b-2), Y1 and Y2 are organic groups, which may be the same or different, and are preferably substituted or unsubstituted aromatic rings. Z1 represents an organic group having a substituted or unsubstituted aromatic ring or heterocyclic ring, or a substituted or unsubstituted aliphatic group, and is preferably a substituted or unsubstituted aromatic ring. Specific examples of the anionic residue represented by formula (b-2) include those represented by either formula (b-3) or (b-4) below.

[0027] [ka]

[0028] [ka]

[0029] The base generator represented by the formula (a) can be used as a curing accelerator for a curable resin composition. The base generator represented by the formula (a) has low catalytic activity at low temperatures (e.g., about 50°C) and does not cure the curable resin composition, but at a desired curing temperature (e.g., about 150°C), it exhibits high catalytic activity and has the latency to cure in a short time (e.g., about 300 to 500 seconds). Therefore, a curable resin composition containing the base generator represented by the formula (a) has excellent storage stability in a one-part form.

[0030] When the curable resin composition is in a liquid state, storage stability can be confirmed by viscosity measurement. In the present invention, storage stability is confirmed by dividing the viscosity of the curable resin composition after standing at 25°C for 24 hours by the initial viscosity. The viscosity after standing at 25°C for 24 hours is preferably 1.8 times or less, and more preferably 1.5 times or less, of the initial viscosity. When the curable resin composition is in a solid state, storage stability can be confirmed by gel time measurement. In the present invention, the gel time retention is calculated by dividing the gel time after standing the curable resin composition at 50°C for 6 hours by the initial gel time. The closer the gel time retention is to 100%, the better the storage stability. Specifically, the gel time retention is preferably 80% or more, and more preferably 90% or more.

[0031] Curability can also be confirmed by gel time and DSC (differential scanning calorimetry). Generally, curability and storage stability are often in a trade-off relationship, making it difficult to satisfy both properties. Therefore, by comparing the curability of curable resin compositions with equivalent storage stability, differences in properties can be compared.

[0032] When the base generator of the present invention is used in electric and electronic parts, it is preferable that the cured product contains as few conductive impurities as possible.

[0033] The method for synthesizing the base generator represented by the above formula (a) is not particularly limited, but it can be obtained as follows.

[0034] The base generator represented by the above formula (a) can be obtained, for example, by an addition reaction between an imidazole derivative and an alkyl halide, followed by an anion exchange reaction with sodium borates or sodium silicates, as required, but is not limited to the above. The addition reaction is preferably carried out without a catalyst, but a catalyst may be used if required.

[0035] Specific examples of organic solvents that can be used in the above addition reaction include alcohols such as methanol and ethanol; alkanes such as hexane, cyclohexane, and heptane; aromatic hydrocarbon compounds such as toluene and xylene; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and anone; ethers such as diethyl ether, tetrahydrofuran, and dioxane; and ester compounds such as ethyl acetate, butyl acetate, and methyl formate.

[0036] The addition reaction proceeds sufficiently even at a temperature of about 20° C. In consideration of reaction time, the reaction temperature is preferably 30 to 200° C., more preferably 40 to 200° C., and particularly preferably 40 to 150° C.

[0037] Next, the curable resin composition of the present invention will be described. The curable resin composition of the present invention contains a base generator represented by the above formula (a).

[0038] [Epoxy resin] The curable resin composition of the present invention may contain an epoxy resin. Preferred examples of the epoxy resin include, but are not limited to, the following. The epoxy resin may be liquid or solid, and may be used alone or in combination.

[0039] Examples of liquid epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AF type epoxy resins, naphthalene type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, phenol novolac type epoxy resins, alicyclic epoxy resins having an ester skeleton, cyclohexane type epoxy resins, cyclohexanedimethanol type epoxy resins, and epoxy resins having a butadiene structure. Specific examples include "RE310S" and "RE410S" (all manufactured by Nippon Kayaku Co., Ltd., bisphenol A type epoxy resin), "RE303S", "RE304S", "RE403S", and "RE404S" (all manufactured by Nippon Kayaku Co., Ltd., bisphenol F type epoxy resin), "HP4032", "HP4032D", and "HP4032SS" (all manufactured by DIC Corporation, naphthalene type epoxy resin), "828", "828US", "828EL", "825", and "828XA" (all manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin), "jE807", and "1750" (all manufactured by Mitsubishi Chemical Corporation, bisphenol F type epoxy resin), and "jER152" (manufactured by Mitsubishi Chemical Corporation, phenol novolac). Examples of epoxy resins include "bisphenol A epoxy resin," "630," and "630LSD" (all manufactured by Mitsubishi Chemical Corporation; glycidylamine epoxy resins), "ZX1059" (manufactured by Nippon Steel Chemical & Material Co., Ltd.; a mixture of bisphenol A epoxy resin and bisphenol F epoxy resin), "EX-721" (manufactured by Nagase ChemteX Corporation; glycidyl ester epoxy resin), "Celloxide 2021P" (manufactured by Daicel Corporation; alicyclic epoxy resin having an ester skeleton), "PB-3600" (manufactured by Daicel Corporation; epoxy resin having a butadiene structure), and "ZX1658" and "ZX1658GS" (all manufactured by Nippon Steel Chemical & Material Co., Ltd.; liquid 1,4-glycidylcyclohexane epoxy resin). These may be used alone or in combination of two or more.

[0040] Preferred examples of solid epoxy resins include bixylenol-type epoxy resins, naphthalene-type epoxy resins, naphthalene-type tetrafunctional epoxy resins, cresol novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol-type epoxy resins, biphenyl-type epoxy resins, naphthylene ether-type epoxy resins, anthracene-type epoxy resins, bisphenol A-type epoxy resins, bisphenol AF-type epoxy resins, and tetraphenylethane-type epoxy resins, and examples of such solid epoxy resins include naphthol-type epoxy resins, bisphenol AF-type epoxy resins, naphthalene-type epoxy resins, and biphenyl-type epoxy resins. Specific examples include "HP4032H" (manufactured by DIC Corporation, naphthalene-type epoxy resin), "HP-4700", "HP-4710" (all manufactured by DIC Corporation, naphthalene-type tetrafunctional epoxy resin), "N-690" (manufactured by DIC Corporation, cresol novolac-type epoxy resin), "N-695" (manufactured by DIC Corporation, cresol novolac-type epoxy resin), "HP-7200", "HP-7200HH", "HP-7200H" (all manufactured by DIC Corporation, dicyclopentadiene-type epoxy resin), "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP-6000" (all manufactured by DIC Corporation, naphthylene ether-type epoxy resin), "EPPN-502H" (manufactured by Nippon Kayaku Co., Ltd., trisphenol-type epoxy resin), "NC-7000L", "NC- 7300" (all manufactured by Nippon Kayaku Co., Ltd., naphthol-cresol novolac type epoxy resin), "NC-3000H", "NC-3000", "NC-3000L", "NC-3100" (all manufactured by Nippon Kayaku Co., Ltd., biphenyl aralkyl type epoxy resin), "XD-1000-2L", "XD-1000-L", "XD-1000-H" (all manufactured by Nippon Kayaku Co., Ltd., dicyclopentadiene type epoxy resin), "ESN475V" (manufactured by Nippon Steel Chemical & Material Co., Ltd., naphthol type epoxy resin), "ESN485" (manufactured by Nippon Steel Chemical & Material Co., Ltd., naphthol novolac type epoxy resin), "YX-4000H", "YX-4000", "YL6121" (all manufactured by Mitsubishi Chemical Corporation, biphenyl type epoxy resin), "YX-4000HK" (manufactured by Mitsubishi Chemical Corporation, bixylenol type epoxy resin),Examples include "YX-8800" (manufactured by Mitsubishi Chemical Corporation, anthracene-type epoxy resin), "PG-100", "CG-500" (manufactured by Osaka Gas Chemicals Co., Ltd., fluorene-based epoxy resin), "YL-7760" (manufactured by Mitsubishi Chemical Corporation, bisphenol AF-type epoxy resin), "YL-7800" (manufactured by Mitsubishi Chemical Corporation, fluorene-type epoxy resin), "jER (registered trademark) 1010" (manufactured by Mitsubishi Chemical Corporation, solid bisphenol A-type epoxy resin), "jER1031S" (manufactured by Mitsubishi Chemical Corporation, tetraphenylethane-type epoxy resin), CNE-195LL (manufactured by Chang Chun Synthetic Resin Co., Ltd., orthocresol novolac-type epoxy resin), and "TEPIC-S" (manufactured by Nissan Chemical Industries, isocyanuric-type epoxy resin). These may be used alone or in combination of two or more.

[0041] Of these epoxy resins, those having high heat resistance are preferred, and therefore bixylenol-type epoxy resins, naphthalene-type epoxy resins, naphthalene-type tetrafunctional epoxy resins, cresol novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol-type epoxy resins, biphenyl-type epoxy resins, naphthylene ether-type epoxy resins, anthracene-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, and tetraphenylethane-type epoxy resins are preferred, and glycidyl ether-type epoxy resins such as naphthol-type epoxy resins, bisphenol AF-type epoxy resins, naphthalene-type epoxy resins, and biphenyl-type epoxy resins are more preferred.

[0042] The base generator represented by the above formula (a) is preferably used in the range of 0.001 to 15 parts by mass, more preferably 0.01 to 5 parts by mass, per 100 parts by mass of the epoxy resin.

[0043] [Hardening agent] The curable resin composition of the present invention may be used in combination with a curing agent. Examples of curing agents that can be used in combination include amine compounds, acid anhydride compounds, phenolic compounds, carboxylic acid compounds, and active ester compounds. Among these, amine compounds, acid anhydride compounds, phenolic compounds, carboxylic acid compounds, and active ester compounds are preferred.

[0044] [Amine compounds] The amine compound is preferably a compound having two or more amino groups in the molecule. For example, 4,4'-methylenebis(2-ethyl-6-methylaniline) (MDEA), diaminodiphenylmethane, 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, diaminodiphenylsulfone, isophoronediamine, naphthalenediamine, aniline novolak (a reaction product of aniline and formalin), N-methylaniline novolak (a reaction product of N-methylaniline and formalin), orthoethylaniline novolak (a reaction product of orthoethylaniline and formalin), a reaction product of 2-methylaniline and formalin, a reaction product of 2,6-diisopropylaniline and formalin, a reaction product of 2,6-diethylaniline and formalin, a reaction product of 2-ethyl-6-ethylaniline and formalin, a reaction product of 2,6-dimethylaniline and formalin, Examples of suitable aniline-based compounds include, but are not limited to, reaction products of aniline with phosphorus, aniline resins obtained by reacting aniline with xylylene chloride, reaction products of aniline with substituted biphenyls (such as 4,4'-bis(chloromethyl)-1,1'-biphenyl and 4,4'-bis(methoxymethyl)-1,1'-biphenyl) as described in Japanese Patent No. 6429862, reaction products of aniline with substituted phenyls (such as 1,4-bis(chloromethyl)benzene, 1,4-bis(methoxymethyl)benzene and 1,4-bis(hydroxymethyl)benzene), 4,4'-(1,3-phenylenediisopropylidene)bisaniline, 4,4'-(1,4-phenylenediisopropylidene)bisaniline, reaction products of aniline with diisopropenylbenzene, and dimer diamine. These compounds may be used singly or in combination.

[0045] [Acid anhydride compounds] Examples of acid anhydride compounds include phthalic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, nadic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, butanetetracarboxylic anhydride, bicyclo[2.2.1]heptane-2,3-dicarboxylic anhydride, and methylbicyclo[2.2.1]heptane-2,3-dicarboxylic anhydride. Commonly available acid anhydride compounds include, but are not limited to, "KAYAHARD (registered trademark) MCD" (manufactured by Nippon Kayaku Co., Ltd.), "RIKACID (registered trademark) MH-700" (manufactured by New Japan Chemical Co., Ltd., 4-methylhexahydrophthalic anhydride), "RIKACID TH" (manufactured by New Japan Chemical Co., Ltd., tetrahydrophthalic anhydride), "RIKACID HH" (manufactured by New Japan Chemical Co., Ltd., hexahydrophthalic anhydride), and RIKACID MH-T (manufactured by New Japan Chemical Co., Ltd.; main component is 4-methylhexahydrophthalic anhydride). These compounds may be used alone or in combination.

[0046] [Phenol compounds] The phenolic compound is preferably a compound having two or more phenolic hydroxyl groups in the molecule. Examples include reaction products of phenols and aldehydes (phenol novolac curing agents), reaction products of phenols and diene compounds, reaction products of phenols and ketones, reaction products of phenols and substituted biphenyls, reaction products of phenols and substituted phenyls, and reaction products of bisphenols and aldehydes. Commonly available phenolic compounds include, but are not limited to, phenol novolac curing agent H-1 (manufactured by UBE Corporation) and cresol novolac curing agent KA-1160 (manufactured by DIC Corporation). These compounds may be used alone or in combination. Specific examples of the above raw materials are given below, but are not limited to these. <Phenols> Phenol, alkyl-substituted phenol, aromatic-substituted phenol, hydroquinone, resorcinol, naphthol, alkyl-substituted naphthol, dihydroxybenzene, alkyl-substituted dihydroxybenzene, dihydroxynaphthalene, etc. <Aldehydes> Formaldehyde, acetaldehyde, alkyl aldehyde, benzaldehyde, alkyl-substituted benzaldehyde, hydroxybenzaldehyde, naphthaldehyde, glutaraldehyde, phthalaldehyde, crotonaldehyde, cinnamaldehyde, furfural, and the like. <Diene compounds> Dicyclopentadiene, terpenes, vinylcyclohexene, norbornadiene, vinylnorbornene, tetrahydroindene, divinylbenzene, divinylbiphenyl, diisopropenylbiphenyl, butadiene, isoprene, and the like. <Ketones> Acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, benzophenone, fluorenone, etc. <Substituted biphenyls> 4,4'-bis(chloromethyl)-1,1'-biphenyl, 4,4'-bis(methoxymethyl)-1,1'-biphenyl, 4,4'-bis(hydroxymethyl)-1,1'-biphenyl and the like. <Substituted phenyls> 1,4-bis(chloromethyl)benzene, 1,4-bis(methoxymethyl)benzene, 1,4-bis(hydroxymethyl)benzene and the like.

[0047] [Carboxylic acid compounds] The carboxylic acid compound is preferably a compound having two or more carboxyl groups in the molecule. Examples include aromatic carboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, benzophenonetetracarboxylic acid, and furandicarboxylic acid, succinic acid, adipic acid, dodecanedioic acid, sebacic acid, thiodipropionic acid, cyclohexanedicarboxylic acid, tris(2-carboxymethyl)isocyanurate, tris(2-carboxyethyl)isocyanurate, tris(2-carboxypropyl)isocyanurate, and bis(2-carboxyethyl)isocyanurate, but are not limited thereto. These compounds may be used alone or in combination.

[0048] [Active ester compounds] An active ester compound refers to a compound containing at least one ester bond in its structure, with an aliphatic chain, an aliphatic ring, or an aromatic ring bonded to both sides of the ester bond. Examples of active ester compounds include phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds, which have two or more highly reactive ester groups per molecule. These compounds are obtained by a condensation reaction between at least one of a carboxylic acid compound, an acid chloride, or a thiocarboxylic acid compound and at least one of a hydroxy compound or a thiol compound. From the viewpoint of improving heat resistance, active ester compounds are preferably obtained from a carboxylic acid compound or an acid chloride and a hydroxy compound, with phenol compounds or naphthol compounds being preferred as the hydroxy compound. Active ester compounds may be used singly or in combination of two or more.

[0049] Examples of the carboxylic acid compound include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, phthalic acid, isophthalic acid, terephthalic acid, pyromellitic acid, 5-hydroxyisophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodiumsulfoisophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, cyclohexanedicarboxylic acid, biphenyldicarboxylic acid, naphthalenedicarboxylic acid, benzophenonedicarboxylic acid, furandicarboxylic acid, 4,4'-dicarboxydiphenyl ether, and 4,4'-dicarboxydiphenyl sulfide. Commercially available products include G4-142MHR (manufactured by Nippon Kayaku Co., Ltd.).

[0050] Examples of the acid chloride include acetyl chloride, acrylic acid chloride, methacrylic acid chloride, malonyl chloride, succinic acid dichloride, diglycolyl chloride, glutaric acid dichloride, suberic acid dichloride, sebacic acid dichloride, adipic acid dichloride, dodecandioyl dichloride, azelaic acid chloride, 2,5-furandicarbonyl dichloride, phthaloyl chloride, isophthaloyl chloride, terephthaloyl chloride, trimesic acid chloride, bis(4-chlorocarbonylphenyl) ether, 4,4'-diphenyldicarbonyl chloride, and 4,4'-azodibenzoyl dichloride.

[0051] Examples of the phenol compound and naphthol compound include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalene, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucinol, benzenetriol, dicyclopentadiene-type diphenol compounds, phenol novolak, and the phenolic resins described below. Here, the term "dicyclopentadiene-type diphenol compound" refers to a diphenol compound obtained by condensing one dicyclopentadiene molecule with two phenol molecules.

[0052] Preferred specific examples of the active ester compound include active ester compounds containing a dicyclopentadiene-type diphenol structure, active ester compounds containing a naphthalene structure, active ester compounds containing an acetylated product of phenol novolac, active ester compounds containing a benzoylated product of phenol novolac, the compound described in Example 2 of WO 2020 / 095829, and the compounds disclosed in WO 2020 / 059625. Among these, active ester compounds containing a naphthalene structure and active ester compounds containing a dicyclopentadiene-type diphenol structure are more preferred. The dicyclopentadiene-type diphenol structure refers to a divalent structural unit consisting of phenylene-dicyclopentylene-phenylene.

[0053] Commercially available active ester compounds include, for example, "EXB9451," "EXB9460," "EXB9460S," "HPC-8000-65T," "HPC-8000H-65TM," "EXB-8000L-65TM," and "EXB-8150-65T" (manufactured by DIC Corporation) as active ester compounds containing a dicyclopentadiene-type diphenol structure, "EXB9416-70BK" (manufactured by DIC Corporation) as an active ester compound containing a naphthalene structure, and "EXB9416-70BK" (manufactured by DIC Corporation) as an active ester compound containing an acetylated product of phenol novolac. Examples of such compounds include "DC808" (manufactured by Mitsubishi Chemical Corporation) as an active ester compound containing a benzoyl compound of phenol novolac, "YLH1026," "YLH1030," and "YLH1048" (manufactured by Mitsubishi Chemical Corporation), "DC808" (manufactured by Mitsubishi Chemical Corporation) as an active ester curing agent which is an acetylated compound of phenol novolac, "EXB-9050L-62M" (manufactured by DIC Corporation) as an active ester curing agent containing a phosphorus atom, and "Unifiner (registered trademark) W-575" (manufactured by Unitika Ltd.) as an active ester compound containing a bisphenol A structure.

[0054] Regarding the compounding ratio of the active ester compound and the epoxy resin, the ratio (α / β) of the active ester equivalent (α) to the epoxy equivalent (β) is preferably 0.5 to 1.5, more preferably 0.8 to 1.2, and even more preferably 0.90 to 1.10. If the ratio is outside this range, excess epoxy groups or active ester groups may remain in the system, which may deteriorate the properties in high-temperature storage tests (e.g., 150°C, 1000 hours) or long-term reliability tests under high-temperature and high-humidity conditions (e.g., temperature: 85°C, humidity: 85%).

[0055] The compounding ratio of epoxy resin to curing agent is preferably 0.5 to 1.5 equivalents (considering carboxylic acid as monofunctional and acid anhydride as monofunctional) of active groups in the curing agent for curable resins that can react with the epoxy groups per equivalent of epoxy groups in the epoxy resin, and particularly preferably 0.5 to 1.2 equivalents. If the ratio is less than 0.5 equivalents or more than 1.5 equivalents per equivalent of epoxy groups, curing may be incomplete and good cured physical properties may not be obtained.

[0056] [Curing accelerator] In addition to the base generator represented by formula (a), the curable resin composition of the present invention may also contain a curing accelerator. As the curing accelerator other than the base generator represented by formula (a), an anionic curing accelerator that accelerates the curing reaction by generating anions upon irradiation with ultraviolet light or visible light or heating, or a cationic curing accelerator that accelerates the curing reaction by generating cations upon irradiation with ultraviolet light or visible light or heating, is preferred.

[0057] [Anionic curing accelerator] Examples of anionic curing accelerators include imidazoles such as 2-methylimidazole, 2-ethylimidazole, and 2-ethyl-4-methylimidazole; trialkylamines such as triethylamine and tributylamine; 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo(5,4,0)-undecene, with 4-dimethylaminopyridine and 1,8-diazabicyclo(5,4,0)-undecene being preferred. Other examples include phosphines such as triphenylphosphine; and quaternary ammonium salts such as tetrabutylammonium salt, triisopropylmethylammonium salt, trimethyldecanylammonium salt, cetyltrimethylammonium salt, and hexadecyltrimethylammonium hydroxide, but are not limited thereto. These may be used alone or in combination.

[0058] [Cationic curing accelerator] Examples of cationic curing accelerators include, but are not limited to, quaternary phosphonium salts such as triphenylbenzylphosphonium salt, triphenylethylphosphonium salt, and tetrabutylphosphonium salt, and transition metal compounds (transition metal salts) such as tin octoate, octope Zn (2-ethylhexanoate), zinc carboxylate (zinc 2-ethylhexanoate, zinc stearate, zinc behenate, zinc myristate), and zinc phosphate ester (zinc octylphosphate, zinc stearylphosphate). These may be used alone or in combination. The counter ion of the quaternary phosphonium salt is not particularly limited and may be a halogen, an organic acid ion, a hydroxide ion, or the like, but is particularly preferably an organic acid ion or a hydroxide ion.

[0059] The curing accelerator other than the base generator represented by the formula (a) is preferably used in the range of 0.001 to 15 parts by mass, more preferably 0.01 to 5 parts by mass, per 100 parts by mass of the epoxy resin.

[0060] [Thermal polymerization initiator] The curable resin composition of the present invention may contain a thermal polymerization initiator. The thermal polymerization initiator is a compound capable of polymerizing an olefin functional group such as an ethylenically unsaturated bond, and examples thereof include an olefin metathesis polymerization initiator, a thermal anionic polymerization initiator, a thermal cationic polymerization initiator, and a thermal radical polymerization initiator. Among these, it is preferable to use a thermal radical polymerization initiator that has curability and appropriate stability. The thermal radical polymerization initiator is a compound that generates radicals upon heating and initiates a chain polymerization reaction. Examples of the thermal radical polymerization initiator include organic peroxides, azo compounds, and benzopinacols. It is preferable to use an organic peroxide because it is effective in controlling the curing temperature, suppresses outgassing, and has little effect on the electrical properties of decomposed products.

[0061] [Organic peroxide] Examples of organic peroxides include ketone peroxides such as methyl ethyl ketone peroxide and acetylacetone peroxide; diacyl peroxides such as benzoyl peroxide; dialkyl peroxides such as dicumyl peroxide and 1,3-bis-(t-butylperoxyisopropyl)-benzene; peroxyketals such as t-butyl peroxybenzoate and 1,1-di-t-butylperoxycyclohexane; α-cumylperoxyneodecanoate, t-butylperoxyneodecanoate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, t-amylperoxy-2-ethylhexanoate, and t-butylperoxy. Examples of the peroxycarbonates include, but are not limited to, alkyl peresters such as di-2-ethylhexyl peroxydicarbonate, t-amylperoxy-3,5,5-trimethylhexanoate, t-butylperoxy-3,5,5-trimethylhexanoate, and t-amylperoxybenzoate; peroxycarbonates such as di-2-ethylhexyl peroxydicarbonate, bis(4-t-butylcyclohexyl)peroxydicarbonate, t-butylperoxyisopropyl carbonate, and 1,6-bis(t-butylperoxycarbonyloxy)hexane; and t-butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxyoctoate, and lauroyl peroxide. These may be used alone or in combination. Among the above organic peroxides, ketone peroxides, diacyl peroxides, hydroperoxides, dialkyl peroxides, peroxyketals, alkyl peresters, peroxycarbonates, etc. are preferred, with dialkyl peroxides being more preferred.

[0062] [Azo compounds] Examples of azo compounds include, but are not limited to, azobisisobutyronitrile, 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2,4-dimethylvaleronitrile), etc. These compounds may be used alone or in combination.

[0063] [Photopolymerization initiator] The curable resin composition of the present invention may contain a photopolymerization initiator. Examples of the photopolymerization initiator include radical photopolymerization initiators, cationic photopolymerization initiators, and photobase initiators. Among these, radical photopolymerization initiators, which have high curability, are preferred.

[0064] [Radical photopolymerization initiator] Examples of the radical photopolymerization initiator include 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)] (manufactured by BASF Japan, "IRGACURE (registered trademark) OXE-01"), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime) (manufactured by BASF Japan, "IRGACURE OXE-02); benzoins such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, and benzoin isobutyl ether; acetophenones such as acetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 2-hydroxy-2-methyl-phenylpropan-1-one, diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one; 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-chloroanthraquinone, and 2-amylanthraquinone. Examples of known general radical photopolymerization initiators include anthraquinones such as thraquinone; thioxanthones such as 2,4-diethylthioxanthone (manufactured by Nippon Kayaku Co., Ltd., "DETX-S"), 2-isopropylthioxanthone, and 2-chlorothioxanthone; ketals such as acetophenone dimethyl ketal and benzil dimethyl ketal; benzophenones such as benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide and 4,4'-bismethylaminobenzophenone; and phosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.

[0065] [Cationic photopolymerization initiator] Examples of the cationic photopolymerization initiator include diazonium salts of Lewis acids, iodonium salts of Lewis acids, sulfonium salts of Lewis acids, phosphonium salts of Lewis acids, other halides, triazine-based photopolymerization initiators, borate-based photopolymerization initiators, and other photoacid generators.

[0066] <Diazonium salt of Lewis acid> Examples of the diazonium salt of a Lewis acid include p-methoxyphenyldiazonium fluorophosphonate and N,N-diethylaminophenyldiazonium hexafluorophosphonate (San-Aid SI-60L / SI-80L / SI-100L, etc., manufactured by Sanshin Chemical Industry Co., Ltd.). <Iodonium salts of Lewis acids> Examples of iodonium salts of Lewis acids include diphenyliodonium hexafluorophosphonate and diphenyliodonium hexafluoroantimonate. Examples of sulfonium salts of Lewis acids include triphenylsulfonium hexafluorophosphonate (Cyracure UVI-6990 manufactured by Union Carbide, etc.) and triphenylsulfonium hexafluoroantimonate (Cyracure UVI-6974 manufactured by Union Carbide, etc.). <Phosphonium salt of Lewis acid> Examples of the phosphonium salt of a Lewis acid include triphenylphosphonium hexafluoroantimonate.

[0067] <Other halides> Other halides include 2,2,2-trichloro-[1-4'-(dimethylethyl)phenyl]ethanone (e.g., Trigonal PI manufactured by AKZO), 2,2-dichloro-1-4-(phenoxyphenyl)ethanone (e.g., Sandray 1000 manufactured by Sandoz), and α,α,α-tribromomethylphenyl sulfone (e.g., BMPS manufactured by Seitetsu Kagaku Co., Ltd.). Examples of the triazine initiator include 2,4,6-tris(trichloromethyl)-triazine, 2,4-trichloromethyl-(4'-methoxyphenyl)-6-triazine (Triazine A manufactured by Panchim, etc.), 2,4-trichloromethyl-(4'-methoxystyryl)-6-triazine (Triazine PMS manufactured by Panchim, etc.), 2,4-trichloromethyl-(piperonyl)-6-triazine (Triazine PP manufactured by Panchim, etc.), 2,4-trichloromethyl-(4'-methoxynaphthyl)-6-triazine (Triazine B manufactured by Panchim, etc.), 2[2'(5-methylfuryl)ethylidene]-4,6-bis(trichloromethyl)-s-triazine (manufactured by Sanwa Chemical Co., Ltd., etc.), and 2(2'-furylethylidene)-4,6-bis(trichloromethyl)-s-triazine (manufactured by Sanwa Chemical Co., Ltd.).

[0068] <Borate-based photopolymerization initiator> Examples of the borate initiator include NK-3876 and NK-3881 manufactured by Nippon Kanko Shikishiki Co., Ltd. <Other photoacid generators, etc.> Other examples of photoacid generators include 9-phenylacridine, 2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2-biimidazole (e.g., Biimidazole manufactured by Kurogane Chemical Industries, Ltd.), 2,2-azobis(2-amino-propane) dihydrochloride (e.g., V50 manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 2,2-azobis[2-(imidazolin-2yl)propane] dihydrochloride (e.g., V50 manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). VA044, etc.), [eta-5-2-4-(cyclopentadecyl)(1,2,3,4,5,6,eta)-(methylethyl)-benzene]iron(II) hexafluorophosphonate (Irgacure 261, manufactured by CibaGeigy, etc.), and bis(y5-cyclopentadienyl)bis[2,6-difluoro-3-(1H-pyri-1-yl)phenyl]titanium (CGI-784, manufactured by CibaGeigy, etc.).

[0069] [Photobase initiator] Examples of the photobase initiator include TRD-001 (manufactured by Nippon Kayaku Co., Ltd.), TRD-008 (manufactured by Nippon Kayaku Co., Ltd.), WPBG-300 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), WPBG-345 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), PBG-266 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), WPBG-018 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), WPBG-027 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), WPBG-140 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and WPBG-165 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

[0070] The amount of the photopolymerization initiator added is preferably 0.01 to 5 parts by mass, and particularly preferably 0.01 to 3 parts by mass, per 100 parts by mass of the curable resin composition. One type of photopolymerization initiator can be used alone, or two or more types can be used in combination.

[0071] [Polymerization inhibitor] The curable resin composition of the present invention may contain a polymerization inhibitor. The inclusion of a polymerization inhibitor improves storage stability and enables control of the reaction initiation temperature. Controlling the reaction initiation temperature makes it easier to ensure fluidity, prevents impregnation into glass cloth and the like from being impaired, and facilitates B-staging, such as prepreg formation. If the polymerization reaction proceeds too much during prepreg formation, problems such as difficulty in lamination during the lamination process are likely to occur.

[0072] The amount of the polymerization inhibitor used is 0.008 to 1 part by mass, and preferably 0.01 to 0.5 parts by mass, relative to 100 parts by mass of the curable resin composition of the present invention.

[0073] Examples of the polymerization inhibitor include phenol-based, sulfur-based, phosphorus-based, hindered amine-based, nitroso-based, and nitroxyl radical-based. One type of polymerization inhibitor may be used alone, or multiple types may be used in combination. Among these, in this embodiment, phenol-based, hindered amine-based, nitroso-based, and nitroxyl radical-based inhibitors are preferred.

[0074] [Phenol-based polymerization inhibitor] Examples of phenolic polymerization inhibitors include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-p-ethylphenol, stearyl-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2,4-bis-(n-octylthio)-6-(4-hydroxy-3, Monophenols such as 5-di-t-butylanilino)-1,3,5-triazine and 2,4-bis[(octylthio)methyl]-o-cresol; 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), Triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl ) propionate], 3,5-di-t-butyl-4-hydroxybenzylphosphonate-diethyl ester, 3,9-bis[1,1-dimethyl-2-{β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]2,4,8,10-tetraoxaspiro[5,5]undecane, bis(3,5-di-t-butyl-4-hydroxybenzylsulfonate)calcium bisphenols;Examples of polymeric phenols include, but are not limited to, 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, bis[3,3'-bis-(4'-hydroxy-3'-t-butylphenyl)butyric acid]glycol ester, tris-(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanurate, 1,3,5-tris(3',5'-di-t-butyl-4'-hydroxybenzyl)-S-triazine-2,4,6-(1H,3H,5H)trione, and tocopherol.

[0075] [Sulfur-based polymerization inhibitor] Examples of sulfur-based polymerization inhibitors include, but are not limited to, dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, and distearyl-3,3'-thiodipropionate.

[0076] [Phosphorus-based polymerization inhibitor] Examples of phosphorus-based polymerization inhibitors include triphenyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite, tris(nonylphenyl) phosphite, diisodecyl pentaerythritol phosphite, tris(2,4-di-t-butylphenyl) phosphite, cyclic neopentanetetrayl bis(octadecyl) phosphite, cyclic neopentanetetrayl bis(2,4-di-t-butylphenyl) phosphite, cyclic neopentanetetrayl bis(2,4-di-t-butyl-4-methylphenyl) phosphite, bis[2-t 10-(3,5-di-t-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(3,5-di-t-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and other oxaphosphaphenanthrene oxides, but are not limited to these.

[0077] [Hindered amine polymerization inhibitor] Examples of hindered amine polymerization inhibitors include ADK STAB (registered trademark) LA-40MP, ADK STAB LA-40Si, ADK STAB LA-402AF, ADK STAB LA-87, ADK STAB LA-82, ADK STAB LA-81, ADK STAB LA-77Y, ADK STAB LA-77G, ADK STAB LA-72, ADK STAB LA-68, ADK STAB LA-63P, ADK STAB LA-57, and ADK STAB LA-52 (all manufactured by ADEKA Corporation); Examples of the terpolymer include, but are not limited to, Chimassorb (registered trademark) 2020FDL, Chimassorb 944FDL, Chimassorb 944LD, Tinuvin (registered trademark) 622SF, Tinuvin PA144, Tinuvin 765, Tinuvin 770DF, Tinuvin XT55FB, Tinuvin 111FDL, Tinuvin 783FDL, and Tinuvin 791FB (all manufactured by BASF Japan Ltd.).

[0078] [Nitroso-based polymerization inhibitors] Examples of nitroso-based polymerization inhibitors include, but are not limited to, p-nitrosophenol, N-nitrosodiphenylamine, and the ammonium salt (cupferron) of N-nitrosophenylhydroxyamine. Of these, the ammonium salt (cupferron) of N-nitrosophenylhydroxyamine is preferred.

[0079] [Nitroxyl radical polymerization inhibitor] Examples of nitroxyl radical polymerization inhibitors include, but are not limited to, di-tert-butyl nitroxide, 2,2,6,6-tetramethylpiperidine-1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-acetoxy-2,2,6,6-tetramethylpiperidine-1-oxyl, and 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl.

[0080] [Flame retardant] The curable resin composition of the present invention may contain a flame retardant. Examples of the flame retardant include halogen-based flame retardants, inorganic flame retardants (antimony compounds, metal hydroxides, nitrogen compounds, boron compounds, etc.), and phosphorus-based flame retardants. From the viewpoint of achieving halogen-free flame retardancy, phosphorus-based flame retardants are preferred.

[0081] The phosphorus-based flame retardant may be either a reactive type or an additive type. Specific examples include phosphate esters such as trimethyl phosphate, triethyl phosphate, tricresyl phosphate, trixylylene phosphate, cresyl diphenyl phosphate, cresyl-2,6-dixylylene phosphate, 1,3-phenylenebis(dixylylene phosphate), 1,4-phenylenebis(dixylylene phosphate), and 4,4'-biphenyl(dixylylene phosphate); phosphanes such as 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 10(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide; phosphorus-containing epoxy compounds obtained by reacting epoxy resins with the active hydrogen of the phosphanes; and red phosphorus. These may be used alone or in combination. Of the above-mentioned exemplified substances, phosphate esters, phosphanes, and phosphorus-containing epoxy compounds are preferred, and 1,3-phenylenebis(dixylilenyl phosphate), 1,4-phenylenebis(dixylilenyl phosphate), 4,4'-biphenyl(dixylilenyl phosphate), and phosphorus-containing epoxy compounds are particularly preferred.

[0082] The content of the flame retardant is preferably in the range of 0.1 to 0.6 parts by mass per 100 parts by mass of the curable resin composition. If the content is less than 0.1 part by mass, the flame retardancy may be insufficient, and if the content is more than 0.6 part by mass, the moisture absorption and dielectric properties of the cured product may be adversely affected.

[0083] [Light stabilizer] The curable resin composition of the present invention may contain a light stabilizer. As the light stabilizer, a hindered amine light stabilizer (HALS) or the like is preferable. Examples of HALS include the reaction product of dibutylamine·1,3,5-triazine·N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-1,6-hexamethylenediamine and N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine, the reaction product of dimethyl succinate-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine, and poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl) Examples of suitable hydroxybenzyl compounds include, but are not limited to, bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butyl malonate, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate, and bis(1,2,2,6,6-pentamethyl-4-piperidyl) 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonate. These compounds may be used alone or in combination.

[0084] The content of the light stabilizer is preferably in the range of 0.001 to 0.1 parts by mass relative to 100 parts by mass of the curable resin composition. If the content is less than 0.001 part by mass, the light stabilizing effect may be insufficient, and if the content is more than 0.1 part by mass, the moisture absorption and dielectric properties of the cured product may be adversely affected.

[0085] [Binder resin] The curable resin composition of the present invention may contain a binder resin. Examples of binder resins include, but are not limited to, polyphenylene ether compounds, polyamide resins, polyimide resins, polybutadiene and modified products thereof, polystyrene and modified products thereof, polyethylene and modified products thereof, butyral resins, acetal resins, acrylic resins, epoxy-nylon resins, NBR-phenol resins, epoxy-NBR resins, and silicone resins. These may be used alone or in combination.

[0086] [Polyphenylene ether compounds] From the viewpoints of heat resistance and electrical properties, the polyphenylene ether compound is preferably a polyphenylene ether compound having an ethylenically unsaturated bond, and more preferably a polyphenylene ether compound having an acrylic group, a methacrylic group, or a styrene structure. Commercially available products include SA-9000 (manufactured by SABIC, a polyphenylene ether compound having a methacrylic group) and OPE-2St 1200 (manufactured by Mitsubishi Gas Chemical Company, a polyphenylene ether compound having a styrene structure). The number average molecular weight (Mn) of the polyphenylene ether compound is preferably 500 to 5000, more preferably 2000 to 5000, and even more preferably 2000 to 4000. If the molecular weight is less than 500, the heat resistance of the cured product tends to be insufficient. On the other hand, if the molecular weight is more than 5000, the melt viscosity increases and sufficient fluidity cannot be obtained, which tends to result in molding defects. In addition, the reactivity decreases, the curing reaction takes a long time, and the amount of unreacted material not incorporated into the curing system increases, which tends to lower the glass transition temperature of the cured product and reduce the heat resistance of the cured product. When the number average molecular weight of the polyphenylene ether compound is 500 to 5000, it is possible to maintain excellent dielectric properties while exhibiting excellent heat resistance, moldability, etc. The number average molecular weight here can be specifically measured using gel permeation chromatography, etc.

[0087] The polyphenylene ether compound may be obtained by a polymerization reaction or by a redistribution reaction of a high-molecular-weight polyphenylene ether compound having a number-average molecular weight of approximately 10,000 to 30,000. Alternatively, these compounds may be used as raw materials and reacted with a compound having an ethylenically unsaturated bond, such as methacrylic acid chloride, acrylic acid chloride, or chloromethylstyrene, to impart radical polymerizability. A polyphenylene ether compound obtained by a redistribution reaction may be obtained, for example, by heating a high-molecular-weight polyphenylene ether compound in a solvent such as toluene in the presence of a phenolic compound and a radical initiator to cause a redistribution reaction. Such polyphenylene ether compounds obtained by a redistribution reaction are preferred because they have hydroxyl groups derived from phenolic compounds at both ends of the molecular chain that contribute to curing, thereby maintaining even higher heat resistance. Furthermore, functional groups can be introduced at both ends of the molecular chain even after modification with a compound having an ethylenically unsaturated bond. Furthermore, polyphenylene ether compounds obtained by a polymerization reaction are preferred because they exhibit excellent fluidity.

[0088] In the case of polyphenylene ether compounds obtained by polymerization, the molecular weight of the polyphenylene ether compound can be adjusted by adjusting the polymerization conditions, etc. Furthermore, in the case of polyphenylene ether compounds obtained by redistribution, the molecular weight of the resulting polyphenylene ether compound can be adjusted by adjusting the conditions, etc. of the redistribution reaction. More specifically, adjusting the amount of the phenolic compound used in the redistribution reaction can be considered. That is, the greater the amount of the phenolic compound, the lower the molecular weight of the resulting polyphenylene ether compound. In this case, poly(2,6-dimethyl-1,4-phenylene ether) or the like can be used as the high-molecular-weight polyphenylene ether compound that undergoes the redistribution reaction. Furthermore, the phenolic compound used in the redistribution reaction is not particularly limited, but preferred are, for example, polyfunctional phenolic compounds having two or more phenolic hydroxyl groups per molecule, such as bisphenol A, phenol novolac, and cresol novolac. These compounds may be used alone or in combination of two or more.

[0089] The content of the polyphenylene ether compound is not particularly limited, but is preferably 5 to 1000 parts by mass, and more preferably 10 to 750 parts by mass, relative to 100 parts by mass of the curable resin composition. When the content of the polyphenylene ether compound is within the above range, it is preferable in that a cured product not only has excellent heat resistance and the like, but also fully exhibits the excellent dielectric properties of the polyphenylene ether compound.

[0090] [Polyamide resin] Examples of polyamide resins include reaction products of one or more of diamines, diisocyanates, and oxazolines with dicarboxylic acids, reaction products of diamines with acid chlorides, and ring-opening polymers of lactam compounds. These may be used alone or in combination. Specific examples of the above raw materials are given below, but are not limited to these. <Diamine> Ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decanediamine, undecanediamine, dodecanediamine, tridecanediamine, tetradecanediamine, pentadecanediamine, hexadecanediamine, heptadecanediamine, octadecanediamine, nonadecanediamine, eicosanediamine, 2-methyl-1,5-diaminopentane, 2-methyl 1,8-diaminooctane, dimer diamine, cyclohexanediamine, bis-(4-aminocyclohexyl)methane, bis(3-methyl-4-aminocyclohexyl)methane, xylylenediamine, norbornanediamine, isophoronediamine, bisaminomethyltricyclodecane, phenylenediamine, diethyltoluenediamine, naphthalenediamine, diaminodiphenylmethane, bis(4-amino-3,5-dimethylphenyl)methane, bis(4-amino-3,5-diethylphenyl)methane , 4,4'-methylenebis-o-toluidine, 4,4'-methylenebis-o-ethylaniline, 4,4'-methylenebis-2-ethyl-6-methylaniline, 4,4'-methylenebis-2,6-diisopropylaniline, 4,4-ethylenedianiline, diaminodiphenyl sulfone, diaminodiphenyl ether, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 4,4-bis(4-aminophenoxy)biphenyl, 2,2-bis[4-(4-amino 4,4'-(1,3-phenylenediisopropylidene)bisaniline, 4,4'-(1,4-phenylenediisopropylidene)bisaniline, 9,9-bis(4-aminophenyl)fluorene, 2,7-diaminofluorene, aminobenzylamine, diaminobenzophenone, and the like. <Diisocyanate> Benzene diisocyanate, toluene diisocyanate, 1,3-bis(isocyanatomethyl)benzene, 1,3-bis(isocyanatomethyl)cyclohexane, bis(4-isocyanatophenyl)methane, isophorone diisocyanate, 1,3-bis(2-isocyanato-2-propyl)benzene, 2,2-bis(4-isocyanatophenyl)hexafluoropropane, dicyclohexylmethane-4,4'-diisocyanate, and the like. <Dicarboxylic acid> Oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, 5-hydroxyisophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodium sulfoisophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, cyclohexanedicarboxylic acid, biphenyldicarboxylic acid, naphthalenedicarboxylic acid, benzophenonedicarboxylic acid, furandicarboxylic acid, 4,4'-dicarboxydiphenyl ether, 4,4'-dicarboxydiphenyl sulfide, etc. <Acid chloride> Acetyl chloride, acrylic acid chloride, methacrylic acid chloride, malonyl chloride, succinic acid dichloride, diglycolyl chloride, glutaric acid dichloride, suberic acid dichloride, sebacic acid dichloride, adipic acid dichloride, dodecandioyl dichloride, azelaic acid chloride, 2,5-furandicarbonyl dichloride, phthaloyl chloride, isophthaloyl chloride, terephthaloyl chloride, trimesic acid chloride, bis(4-chlorocarbonylphenyl) ether, 4,4'-diphenyldicarbonyl chloride, 4,4'-azodibenzoyl dichloride and the like. <Lactam> ε-caprolactam, ω-undecanelactam, ω-laurolactam, and the like.

[0091] [Polyimide resin] Examples of polyimide resins include, but are not limited to, reaction products of the above diamines with the tetracarboxylic dianhydrides listed below. Specific examples include LDFI089 (a polyimide compound obtained by the method described in WO2023013224A1). These may be used alone or in combination. <Tetracarboxylic acid dianhydride> 4,4'-(Hexafluoroisopropylidene)diphthalic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-cyclohexene-1,2dicarboxylic anhydride, pyromellitic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 2,2',3, 3'-Biphenyltetracarboxylic dianhydride, methylene-4,4'-diphthalic dianhydride, 1,1-ethylidene-4,4'-diphthalic dianhydride, 2,2'-propylidene-4,4'-diphthalic dianhydride, 1,2-ethylene-4,4'-diphthalic dianhydride, 1,3-trimethylene-4,4'-diphthalic dianhydride, 1,4-tetramethylene-4,4'-diphthalic dianhydride, 1,5-pentamethylene-4,4'-diphthalic dianhydride, 4,4'-oxydiphthalic dianhydride, thio-4,4'-diphthalic dianhydride, sulfonyl-4,4'-diphthalic acid Dianhydride, 1,3-bis(3,4-dicarboxyphenyl)benzene dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,3-bis[2-(3,4-dicarboxyphenyl)-2-propyl]benzene dianhydride, 1,4-bis[2-(3,4-dicarboxyphenyl)-2-propyl]benzene dianhydride, bis[3-(3,4-dicarboxyphenoxy)phenyl]methane dianhydride, bis[4-(3,4-dicarboxyphenoxy)phenyl]meth 2,2-bis[3-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, bis(3,4-dicarboxyphenoxy)dimethylsilane dianhydride, 1,3-bis(3,4-dicarboxyphenyl)-1,1,3,3-tetramethyldisiloxane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3,4,9,10-Perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride, ethylenetetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, cyclohexane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride tetracarboxylic acid dianhydride, 3,3',4,4'-bicyclohexyltetracarboxylic acid dianhydride, carbonyl-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, methylene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 1,2-ethylene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 1,1-ethylidene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 2,2-propylidene- 4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, oxy-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, thio-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, sulfonyl-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, rel-[1S,5R,6R]-3-oxabicyclo[3,2 ,1]Octane-2,4-dione-6-spiro-3'-(tetrahydrofuran-2',5'-dione), 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid anhydride, ethylene glycol-bis-(3,4-dicarboxylic acid anhydride phenyl) ether, 4,4'-biphenyl bis(trimellitic acid monoester acid anhydride), 9,9'-bis(3,4-dicarboxyphenyl)fluorene dianhydride, etc.,

[0092] [Allyl compounds] Examples of the allyl compound include monoallyl isocyanurate, diallyl isocyanurate, triallyl isocyanurate, etc. Specific examples include "TAIC" (manufactured by Mitsubishi Chemical Corporation), "MA-DGIC", and "DA-MGIC" (all manufactured by Shikoku Chemical Industry Co., Ltd.).

[0093] [Polybutadiene and its modified products] Polybutadiene and its modified products are compounds having polybutadiene or a structure derived from polybutadiene in the molecule. The unsaturated bonds in the polybutadiene-derived structure may be partially or entirely converted to single bonds by hydrogenation. Examples of polybutadiene and its modified products include, but are not limited to, polybutadiene, hydroxyl-terminated polybutadiene, (meth)acrylate-terminated polybutadiene, carboxylic acid-terminated polybutadiene, amine-terminated polybutadiene, and styrene-butadiene rubber. These may be used alone or in combination. Of these, polybutadiene or styrene-butadiene rubber is preferred from the viewpoint of dielectric properties. Examples of styrene-butadiene rubber (SBR) include RICON-100, RICON-181, and RICON-184 (all manufactured by Cray Valley Chemical Industries, Ltd.) and 1,2-SBS (manufactured by Nippon Soda Co., Ltd.). Examples of polybutadienes include B-1000, B-2000, and B-3000 (all manufactured by Nippon Soda Co., Ltd.). The molecular weight of polybutadiene and styrene-butadiene rubber is preferably a weight-average molecular weight of 500 to 10,000, more preferably 750 to 7,500, and even more preferably 1,000 to 5,000. Below the lower limit of the above range, the amount of volatilization is high, making it difficult to adjust the solids content during prepreg production. Above the upper limit of the above range, compatibility with other curable resins deteriorates. In general, compounds containing heteroatoms such as oxygen and nitrogen, such as bismaleimides and polymaleimides, have difficulty ensuring compatibility with low-polarity compounds, such as compounds composed mainly of hydrocarbons or compounds composed solely of hydrocarbons, due to their polarity. On the other hand, the compound of the present embodiment does not have a skeleton design in which heteroatoms such as oxygen and nitrogen are actively introduced, and therefore has excellent compatibility with materials having low polarity and low dielectric properties and compounds composed only of hydrocarbons.

[0094] [Polystyrene and its modified products] Polystyrene and its modified products are polystyrene or compounds having a structure derived from polystyrene in the molecule. Examples of polystyrene and modified products thereof include polystyrene, styrene-2-isopropenyl-2-oxazoline copolymer (Epocross RPS-1005, RP-61, both manufactured by Nippon Shokubai Co., Ltd.), SEP (styrene-ethylene-propylene copolymer: Septon 1020, manufactured by Kuraray Co., Ltd.), SEPS (styrene-ethylene-propylene-styrene copolymer: Septon 2002, Septon 2004F, Septon 2005, Septon 2006, Septon 2063, Septon 2104, all manufactured by Kuraray Co., Ltd.), SEEPS (styrene-ethylene / ethylene-propylene-styrene block copolymer: Septon 4003, Septon 4044, Septon 4055, Septon 4077, Septon 4099, all manufactured by Kuraray Co., Ltd.), SEBS (styrene-ethylene-butylene-styrene copolymer: Septon 4003, Septon 4044, Septon 4055, Septon 4077, Septon 4099, all manufactured by Kuraray Co., Ltd.), Examples of suitable block copolymers include Septon 8004, Septon 8006, and Septon 8007L (all manufactured by Kuraray Co., Ltd.), SEEPS-OH (a styrene-ethylene / ethylene-propylene-styrene block copolymer having a terminal hydroxyl group: Septon HG252, manufactured by Kuraray Co., Ltd.), SIS (styrene-isoprene-styrene block copolymer: Septon 5125 and Septon 5127, both manufactured by Kuraray Co., Ltd.), hydrogenated SIS (hydrogenated styrene-isoprene-styrene block copolymer: Hybrar 7125F and Hybrar 7311F, both manufactured by Kuraray Co., Ltd.), and SIBS (styrene-isobutylene-styrene block copolymer: SIBSTAR 073T, SIBSTAR 102T, and SIBSTAR 103T (all manufactured by Kaneka Corporation), and Septon V9827 (manufactured by Kuraray Co., Ltd.)), but are not limited to these. These may be used alone or in combination. Polystyrene and its modified products are preferably free of unsaturated bonds, since they have higher heat resistance and are less susceptible to oxidative degradation. The weight-average molecular weight of polystyrene and its modified products is not particularly limited as long as it is 10,000 or more, but if it is too large, compatibility with not only polyphenylene ether compounds but also low-molecular-weight components with a weight-average molecular weight of about 50 to 1,000 and oligomer components with a weight-average molecular weight of about 1,000 to 5,000 deteriorates, making it difficult to ensure mixing and solvent stability. Therefore, the weight-average molecular weight is preferably about 10,000 to 300,000.

[0095] [Polyethylene and its modified products] Polyethylene and its modified products are polyethylene or compounds having a polyethylene-derived structure in the molecule. Examples of polyethylene and its modified products include, but are not limited to, ethylene-propylene copolymers, ethylene-styrene copolymers, ethylene-propylene-ethylidene norbornene copolymers (EBT: K-8370EM, K-9330M, etc., manufactured by Mitsui Chemicals, Inc.), ethylene-propylene-vinyl norbornene copolymers (VNB-EPT: PX-006M, PX-008M, PX-009M, etc., manufactured by Mitsui Chemicals, Inc.), ethylene-vinyl alcohol copolymers, and ethylene-vinyl acetate copolymers. From the viewpoint of improving heat resistance, it is preferable to use ethylene-propylene-ethylidene norbornene copolymers or ethylene-propylene-vinyl norbornene copolymers containing a crosslinkable structure. These may be used alone or in combination. There are no particular restrictions on the weight-average molecular weight of polyethylene and modified polyethylenes thereof as long as it is 10,000 or more. However, if it is too large, compatibility with not only polyphenylene ether compounds but also low-molecular-weight components with a weight-average molecular weight of about 50 to 1,000 and oligomer components with a weight-average molecular weight of about 1,000 to 5,000 deteriorates, making it difficult to ensure mixing and solvent stability. Therefore, it is preferably about 10,000 to 300,000.

[0096] The amount of binder resin is preferably within a range that does not impair the flame retardancy and heat resistance of the cured product, and is preferably 0.05 to 50 parts by mass, more preferably 0.05 to 20 parts by mass, per 100 parts by mass of the curable resin composition, as needed. Among these compounds, polyphenylene ether compounds, polybutadiene and modified polybutadiene, and polystyrene and modified polybutadiene are preferred in terms of the balance of heat resistance, adhesion, and dielectric properties. The inclusion of these compounds can improve the brittleness of the cured product and adhesion to metals, and can suppress package cracking during solder reflow and reliability tests such as thermal cycling.

[0097] [Inorganic filler] The curable resin composition of the present invention may contain an inorganic filler. Examples of inorganic fillers include, but are not limited to, powders such as fused silica, crystalline silica, porous silica, alumina, zircon, calcium silicate, calcium carbonate, quartz powder, silicon carbide, silicon nitride, boron nitride, zirconia, aluminum nitride, graphite, forsterite, steatite, spinel, mullite, titania, talc, clay, iron oxide, asbestos, and glass powder, as well as inorganic fillers obtained by shaping these into spherical or crushed forms. These fillers may be used alone or in combination.

[0098] When preparing a curable resin composition for a semiconductor sealant, a thermally conductive material, or the like, the amount of inorganic filler used is preferably 80 to 92 parts by mass, and more preferably 83 to 90 parts by mass, per 100 parts by mass of the curable resin composition. When preparing a curable resin composition for an interlayer insulating layer-forming material, or a substrate material such as a copper-clad laminate, prepreg, or RCC, the amount of inorganic filler used is preferably 5 to 80 parts by mass, and more preferably 10 to 60 parts by mass, per 100 parts by mass of the curable resin composition.

[0099] The curable resin composition of the present embodiment may further contain a compound having an ethylenically unsaturated bond, an isocyanate compound, a maleimide compound, a cyanate compound, or the like, and these may be used alone or in combination.

[0100] [Compounds containing ethylenically unsaturated bonds] A compound containing an ethylenically unsaturated bond is a compound that has one or more ethylenically unsaturated bonds in the molecule that can be polymerized by heat or light, regardless of whether a polymerization initiator is used or not. Examples of the compound containing an ethylenically unsaturated bond include (meth)acrylate compounds such as isobornyl acrylate and acryloylmorpholine, reaction products of the above phenolic compounds with ethylenically unsaturated bond-containing halogen compounds (chloromethylstyrene, allyl chloride, methallyl chloride, acrylic acid chloride, methacrylic acid chloride, etc.), reaction products of ethylenically unsaturated bond-containing phenols (2-allylphenol, 2-propenylphenol, 4-allylphenol, 4-propenylphenol, eugenol, isoeugenol, etc.) with halogen compounds (1,4-bis(chloromethyl)benzene, 4, Examples of the reactant include, but are not limited to, reaction products of epoxy resins or alcohols with (meth)acrylic acids (acrylic acid, methacrylic acid, etc.), reaction products of epoxy resins or alcohols with (meth)acrylic acids (acrylic acid, methacrylic acid, etc.), and acid-modified products thereof, styrene resins, allyl group-containing compounds, acenaphthyl group-containing compounds (acenaphthylene, etc.), and isocyanuric acid derivatives (TAIC manufactured by Mitsubishi Chemical Corporation, MA-DGIC, DA-MGIC, MeDAIC, L-DAIC, DD-1 manufactured by Shikoku Chemical Industry Co., Ltd.). These may be used alone or in combination.

[0101] As the (meth)acrylate compound, commercially available products can be used, for example, STR-2000 (Zylok type styrene resin, manufactured by Nippon Kayaku Co., Ltd.), KAYARAD (registered trademark) R-604, KAYARAD (registered trademark) R-684, KAYARAD (registered trademark) HX-220, KAYARAD (registered trademark) HX-620, KAYARAD (registered trademark) DPHA, KAYARAD (registered trademark) DPCA-60, KAYARAD (registered trademark) DPEA-12, KAYARAD (registered trademark) PET-30, KAYARAD (registered trademark) ZXR-1801H (trade name, manufactured by Nippon Kayaku Co., Ltd.), KAYARAD (registered trademark) ZXR-1806H (trade name), Examples of suitable ethylenically unsaturated compounds include KAYARAD (registered trademark) ZXR-1810H (trade name), KAYARAD (registered trademark) ZXR-1889H (trade name), KAYARAD (registered trademark) ZCR-6001H, KAYARAD (registered trademark) ZCR-6002H, KAYARAD (registered trademark) ZCR-8001H, KAYARAD (registered trademark) ZCR-8002H, KAYARAD (registered trademark) ZAR-2001H, KAYARAD (registered trademark) ZAR-2002H, KAYARAD (registered trademark) UXE-3000, KAYARAD (registered trademark) PCR-1222H, CCR-1171H, and KAYARAD (registered trademark) ZFR-1494H. These compounds having an ethylenically unsaturated bond can be used alone or in appropriate mixtures of two or more.

[0102] [Isocyanate compounds] An isocyanate compound is a compound having two or more isocyanate groups in the molecule. Examples of isocyanate resins include, but are not limited to, aromatic diisocyanates such as p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylene diisocyanate, m-xylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and naphthalene diisocyanate; aliphatic or alicyclic diisocyanates such as isophorone diisocyanate, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hydrogenated xylene diisocyanate, norbornene diisocyanate, and lysine diisocyanate; polyisocyanates such as biuret compounds of one or more types of isocyanate monomers or isocyanate compounds obtained by trimerizing the above-mentioned diisocyanate compounds; and polyisocyanates obtained by a urethanization reaction between the above-mentioned isocyanate compounds and polyol compounds. These may be used alone or in combination.

[0103] [Maleimide compounds] A maleimide compound is a compound having one or more maleimide groups in the molecule. Examples of maleimide compounds include phenylmaleimide, 4,4'-diphenylmethane bismaleimide, polyphenylmethane maleimide, m-phenylene bismaleimide, 2,2'-bis[4-(4-maleimidophenoxy)phenyl]propane, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 4,4'-diphenylether bismaleimide, 4,4'-diphenylsulfone bismaleimide, 1,3-bis(3-maleimidophenoxy)benzene, 1,3-bis(4-maleimidophenoxy)benzene), and Xylox-type maleimide compounds (anilix). Maleimide, manufactured by Mitsui Chemicals Fine Co., Ltd.), biphenylaralkyl-type maleimide compounds (solidified by distilling off the solvent under reduced pressure from a resin solution containing the maleimide compound (M2) described in Example 4 of Japanese Patent Application Laid-Open No. 2009-001783), bisaminocumylbenzene-type maleimide (maleimide compounds described in International Publication No. 2020 / 054601), maleimide compounds having an indane structure described in Japanese Patent Application Laid-Open No. 6629692 or International Publication No. 2020 / 217679, MATERIAL STAGE Vol. 18, No. 12 2019 "Continued Story of Epoxy Resin CAS Numbers - Hardener CAS Number Memorandum No. 31 Bismaleimide (1)" and MATERIAL STAGE Vol. 19, No. 2 2019 "Continued Story of Epoxy Resin CAS Numbers - Hardener CAS Number Memorandum No. 32" Examples of commercially available maleimide compounds include those described in "Bismaleimides (2)." Commercially available products include MIR-3000-70MT (biphenylaralkyl maleimide compound, manufactured by Nippon Kayaku Co., Ltd.) and MIZ-001 (manufactured by Nippon Kayaku Co., Ltd.), but are not limited to these. These compounds may be used alone or in combination.

[0104] [Cyanate compounds] Cyanate compounds are cyanate ester compounds obtained by reacting phenolic resins with cyanogen halides. Specific examples include dicyanatobenzene, tricyanatobenzene, dicyanatonaphthalene, dicyanatobiphenyl, 2,2'-bis(4-cyanatophenyl)propane, bis(4-cyanatophenyl)methane, bis(3,5-dimethyl-4-cyanatophenyl)methane, 2,2'-bis(3,5-dimethyl-4-cyanatophenyl)propane, 2,2'-bis(4-cyanatophenyl)ethane, 2,2'-bis(4-cyanatophenyl)hexafluoropropane, bis(4-cyanatophenyl)sulfone, bis(4-cyanatophenyl)thioether, phenol novolac cyanate, and phenol-dicyclopentadiene co-condensates in which the hydroxyl groups have been converted to cyanate groups. Commercially available products include, but are not limited to, SYTESTER TA (bisphenol A cyanate resin, manufactured by Mitsubishi Gas Chemical Co., Ltd.) These may be used alone or in combination. Furthermore, the cyanate compound whose synthesis method is described in Japanese Patent Application Laid-Open No. 2005-264154 is particularly preferred as the cyanate compound because it has low moisture absorption, flame retardancy, and excellent dielectric properties.

[0105] The cyanate compound may optionally contain a catalyst such as zinc naphthenate, cobalt naphthenate, copper naphthenate, lead naphthenate, zinc octoate, tin octoate, lead acetylacetonate, or dibutyltin maleate in order to trimerize the cyanate group to form a sym-triazine ring. The catalyst is preferably used in an amount of 0.0001 to 0.10 parts by mass, and more preferably 0.00015 to 0.0015 parts by mass, per 100 parts by mass of the cyanate compound and curable resin composition.

[0106] The curable resin composition of the present invention may be used in combination with a commonly available latent curing catalyst. Examples of commonly available latent curing catalysts include tetraphenylphosphonium tetraphenylborate (TPP-K manufactured by Hokko Chemical Co., Ltd.), tetraphenylborate salt of benzyl-modified 1,8-diazabicyclo[5,4,0]-7-undecene (DBU) (U-CAT5002 manufactured by San-Apro Co., Ltd.), phenolic resin salt of 1,5-diazabicyclo[4,3,0]-5-nonene (DBN) (U-CAT881 manufactured by San-Apro Co., Ltd.), adduct-type latent curing agents (PN-23J manufactured by Ajinomoto Fine-Techno Co., Ltd., Fujicure FXR-1030 manufactured by T&K TOKA Co., Ltd., etc.), and thiol-based liquid latent curing agents (Fujicure 7004 manufactured by T&K TOKA Co., Ltd.), but are not limited thereto. These may be used alone or in combination.

[0107] [Additives] The curable resin composition of the present invention may contain additives, such as modified acrylonitrile copolymers, polyethylene, fluororesins, silicone gels, silicone oils, surface treatment agents for fillers such as silane coupling agents, release agents, and colorants such as carbon black, phthalocyanine blue, and phthalocyanine green.

[0108] If necessary, the curable resin composition of the present invention may contain, as additives other than those described above, commonly used additives for epoxy resins, such as dyes, fluorescent brighteners, reinforcing materials, white pigments or other pigments, nucleating agents, surfactants, plasticizers, viscosity modifiers, flowability modifiers, antioxidants, ultraviolet absorbers, and light stabilizers.

[0109] The amount of the additive to be added is preferably 1,000 parts by mass or less, more preferably 700 parts by mass or less, per 100 parts by mass of the curable resin composition.

[0110] The curable resin composition of the present invention may be prepared by any method without particular limitation, for example, by premixing the components in predetermined amounts and then mixing or melt-kneading them using a roll mixer, kneader, extruder, or the like.

[0111] The curable resin composition of the present invention may be cured by any known curing method, such as a sealed curing oven or a tunnel oven capable of continuous curing. The heat source is also not particularly limited, and any known method, such as hot air circulation, infrared heating, or high-frequency heating, may be used. The curing temperature and curing time may be appropriately set.

[0112] The use of the curable resin composition of the present invention is not particularly limited, and it can be applied to various fields and products in which resin materials are used, and can be widely used in electrical and electronic materials, construction, civil engineering, automotive, medical materials, etc.

[0113] For example, examples of applications in electrical and electronic materials include adhesives, adhesive films, sealants, semiconductor encapsulants, insulating materials, heat conductive and heat dissipating materials, hot melt materials, paints, potting agents, etc., but more specific examples include encapsulating materials and layer forming materials for electronic components such as printed wiring boards, copper foils, copper-clad laminates, interlayer insulating materials, wiring coating films, resin-coated copper foils (RCC), and prepregs; forming materials for display devices such as color filters, films for flexible displays, resist materials, solder resist inks, and alignment films; forming materials for semiconductor devices such as resist materials and buffer coat films; and forming materials for optical components such as holograms, optical waveguides, optical circuits, optical circuit components, and antireflection films. [Example]

[0114] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" and "%" in the text are based on mass.

[0115] [ 1H-NMR measurement] 1 H-NMR was measured by the following method. A 10 mg sample was dissolved in approximately 0.5 ml of deuterated dimethyl sulfoxide (DMSO-d6), placed in a φ5 mm sample tube, and measured with a nuclear magnetic resonance spectrometer (JNM-ECS400, manufactured by JEOL Ltd.). The shift value was measured using DMSO (δ = 2.49 ppm) as the reference.

[0116] [Synthesis Example 1] Synthesis of Compound C1 7.20 parts of 1,2-dimethylimidazole (1.2DMZ: manufactured by Shikoku Chemicals Corporation) and 30.59 parts of acetone were placed in a 300 ml separable flask and heated to 50°C to dissolve. Then, 13.20 parts of benzyl bromide were added dropwise, taking care to avoid heat generation, and the mixture was allowed to react for 2 hours. The mixture was then cooled to 30°C to crystallize. The solid was collected by suction filtration and washed three times with an excess amount of acetone. The obtained wet cake was dried under reduced pressure at 80°C for 1 hour to obtain compound C1 represented by the following formula (1) as a white solid in a yield of 83%. The obtained C1 1 The H-NMR spectrum data is shown in Figure 1.

[0117] [ka]

[0118] [Synthesis Example 2] Synthesis of Compound C2 A 300 ml separable flask was charged with 12.00 parts of sodium tetraphenylborate and 14.23 parts of methanol and dissolved. A solution prepared by dissolving compound C1 (9.09 parts) in 15.82 parts of methanol was slowly added dropwise to this solution, and the mixture was allowed to react for 2 hours, resulting in the precipitation of crystals. The solid was collected by suction filtration and washed three times with an excess amount of methanol. The obtained wet cake was dried under reduced pressure at 80°C for 1 hour, yielding compound C2 represented by the following formula (2) as a white solid in a yield of 99%. 1 The H-NMR spectrum data is shown in Figure 2.

[0119] [ka]

[0120] [Synthesis Example 3] Synthesis of Compound C3 A 300 ml separable flask was charged with 11.56 parts of 1-benzyl-2-phenylimidazole (1B2PZ: manufactured by Shikoku Chemical Industries Co., Ltd.) and 30.39 parts of acetone, and the mixture was heated to 50°C to dissolve. Then, 8.70 parts of benzyl bromide was added dropwise, taking care not to generate heat, and the mixture was allowed to react for 2 hours. The mixture was then concentrated under reduced pressure while maintaining the temperature at 50°C until acetone no longer distilled off. The resulting waxy concentrate was diluted with 31.14 parts of methanol, and a solution prepared by dissolving 19.32 parts of sodium tetraphenylborate in 34.26 parts of methanol was slowly added dropwise. The mixture was allowed to react for 2 hours, resulting in the precipitation of crystals. The solid was recovered by suction filtration and washed three times with an excess amount of methanol. The resulting wet cake was dried under reduced pressure at 80°C for 1 hour to obtain compound C3 represented by the following formula (3) as a white solid in a yield of 31.62 parts by mass. 1 The H-NMR spectrum data is shown in Figure 3.

[0121] [ka]

[0122] [Comparative Synthesis Example 1] Synthesis of Compound C4 A 300 ml separable flask was charged with 7.92 parts of phenyltrimethoxysilane, 6.40 parts of 2,3-dihydroxynaphthalene, and 40 parts of methanol, and the mixture was dissolved. A solution of 1.6 parts of sodium hydroxide dissolved in 7.9 parts of methanol was added to the resulting solution, and the mixture was stirred for 30 minutes. A solution of 16.80 parts of tetraphenylphosphonium bromide dissolved in 19.9 parts of methanol was slowly added dropwise to the resulting solution, and the mixture was allowed to react for 2 hours, resulting in the precipitation of crystals. The solid was recovered by suction filtration and washed three times with an excess amount of methanol. The resulting wet cake was dried under reduced pressure at 45°C for 4 hours, yielding compound C4 represented by the following formula (4) as a gray solid in a yield of 72%. The resulting C4 1 The H-NMR spectrum data is shown in Figure 4.

[0123] [ka]

[0124] [Synthesis Example 4] Synthesis of Compound C5 A 300 ml separable flask was charged with 5.53 parts of 1,2-dimethylimidazole (1.2DMZ: manufactured by Shikoku Chemicals Corporation) and 16.31 parts of acetone, and the mixture was heated to 50°C to dissolve the components. A solution of 10.00 parts of 3-chloropropiophenone dissolved in 6.99 parts of acetone was added to this solution, while taking care to avoid heat generation, and the mixture was allowed to react for 2 hours. The mixture was then cooled to 30°C to crystallize. The solid was recovered by suction filtration and washed three times with an excess amount of acetone. The resulting wet cake was dried under reduced pressure at 80°C for 1 hour. 5.00 parts of the resulting white solid was dissolved in 15.00 parts of methanol. A solution of 7.11 parts of sodium tetraphenylborate dissolved in 15.00 parts of methanol was slowly added dropwise to this solution, and the mixture was allowed to react for 2 hours, resulting in the precipitation of crystals. The solid was recovered by suction filtration and washed three times with an excess amount of methanol. The obtained wet cake was dried under reduced pressure at 80°C for 1 hour to obtain a compound C5 represented by the following formula (5) as a white solid with a yield of 9.88 parts by mass. 1 The H-NMR spectrum data is shown in Figure 5.

[0125] [ka]

[0126] [Synthesis Example 5] Synthesis of Compound C6 A 300 ml separable flask was charged with 13.48 parts of 1-benzyl-2-phenylimidazole (1B2PZ: manufactured by Shikoku Chemicals Corporation) and 24.65 parts of acetone, and the temperature was raised to 50°C to dissolve the compound. A solution of 10.00 parts of 3-chloropropiophenone dissolved in 10.57 parts of acetone was added to the resulting solution, and the mixture was allowed to react for 2 hours. The pressure was then reduced while the temperature remained at 50°C, and the mixture was concentrated under reduced pressure until acetone no longer distilled off. 5.00 parts of the resulting waxy concentrate was diluted with 8.75 parts of methanol, and a solution of 4.67 parts of sodium tetraphenylborate dissolved in 8.75 parts of methanol was slowly added dropwise. The mixture was allowed to react for 2 hours, resulting in the precipitation of a solid. The solid was recovered by suction filtration and washed three times with an excess amount of methanol. The resulting solid was dried under reduced pressure at 80°C for 1 hour, yielding compound C6 represented by the following formula (6) as a yellow solid with a yield of 6.90 parts by mass. 1 The H-NMR spectrum data is shown in Figure 6.

[0127] [ka]

[0128] [Examples 1 to 4 and Comparative Example 1] Phenol novolac curing agent PN(H-1) (hydroxyl equivalent: 107, manufactured by UBE Corporation), epoxy resin NC-3000 (hydroxyl equivalent: 276, manufactured by Nippon Kayaku Co., Ltd.), and various curing accelerators were added in the amounts shown in Table 1, and 3.45 parts of acetone was added. The mixture was stirred and mixed, and then dried under reduced pressure at 80°C for 1 hour to obtain a solid curable resin composition (equivalent ratio of epoxy equivalent to hydroxyl equivalent: 1.0).

[0129] [150℃ gel time measurement] Appropriate amounts of the curable resin compositions obtained in Examples 1 to 4 and Comparative Example 1 were placed on a hot plate at 150°C and stirred using a Teflon (registered trademark) spatula, and the time until the torque increased by 20% from the initial value was measured using a gel time measuring device (Madoka MDK13G manufactured by Cyber ​​Corporation). The result is shown in Table 1 as the initial gel time "Initial (1)". In addition, after storing the curable resin composition at 50°C for 6 hours, the gel time was measured in the same manner as above, and the gel time after storing at 50°C for 6 hours was shown in Table 1 as "After storing at 50°C for 6 hours (2)." The gel time retention rate was calculated by dividing the gel time (2) after storage at 50°C for 6 hours by the initial gel time (1). The results are shown in Table 1.

[0130] [DSC measurement] The curable resin compositions obtained in Examples 1 to 4 and Comparative Example 1 were measured using a thermogravimetric differential thermal analyzer (TGA / DSC1 manufactured by Mettler-Toledo) under conditions of a measurement temperature range of 50 to 350°C and a heating rate of 10°C / min, and the exothermic peak top temperatures are shown in Tables 1 and 2.

[0131] [Table 1]

[0132] [Table 2]

[0133] As shown in Table 1, it was confirmed that the curable resin compositions of the Examples had higher gel time retention rates and better storage stability than the curable resin compositions of the Comparative Examples.

[0134] <Curing test> [Reference example 1] 0.2 parts of the compound (C3) obtained in Synthesis Example 3, 20 parts of NC-3000 (manufactured by Nippon Kayaku Co., Ltd., biphenylaralkyl type epoxy resin), 0.5 parts of KAYAHARD GPH-65 (manufactured by Nippon Kayaku Co., Ltd., biphenylaralkyl type phenol resin), 0.5 parts of MDEA: 4,4'-methylenebis(2-ethyl-6-methylaniline) (manufactured by Tokyo Chemical Industry Co., Ltd., amine resin), 0.5 parts of KAYAHARD MCD (manufactured by Nippon Kayaku Co., Ltd., acid anhydride compound), 0.5 parts of Unifiner W-575 (manufactured by Unitika Ltd., activated ester resin), 0.5 parts of G4-142MHR (manufactured by Nippon Kayaku Co., Ltd., carboxylic acid compound), 2.5 parts of MIR-3000-70MT (manufactured by Nippon Kayaku Co., Ltd., maleimide resin), 2.5 parts of MIZ-001 (manufactured by Nippon Kayaku Co., Ltd., maleimide resin), CYTESTER 0.5 parts of TA (Mitsubishi Gas Chemical Co., Ltd., bisphenol A type cyanate resin), 60 parts of OPE-2St 2200 (Mitsubishi Gas Chemical Co., Ltd., polyphenylene ether compound), 3 parts of STR-2000 (Nippon Kayaku Co., Ltd., styrene resin), 1 part of KAYARAD R-684 (Nippon Kayaku Co., Ltd., acrylate resin), 1 part of polyamide-imide resin obtained by the method described in WO2023013224A1, 1 part of Septon 2104 (Kuraray Co., Ltd., hydrogenated styrene-based thermoplastic elastomer), 1 part of TAIC: triallyl isocyanurate (Mitsubishi Chemical Co., Ltd., allyl compound), 0.5 parts of acenaphthylene (Tokyo Chemical Industry Co., Ltd.), 0.5 parts of phenylmaleimide (Tokyo Chemical Industry Co., Ltd.). The mixture was mixed in the following proportions: 1 part of DICY: dicyandiamide (Tokyo Chemical Industry Co., Ltd., amide compound), 1 part of DCP: dicumyl peroxide (Kayaku Nouryon Co., Ltd., curing accelerator), 0.5 parts of 2E4MZ: 2-ethyl-4-methylimidazole (Shikoku Chemical Industry Co., Ltd., curing accelerator), 0.5 parts of TPP: triphenylphosphine (Hokuko Chemical Co., Ltd., curing accelerator), 0.1 parts of Octope Zn (Hope Pharmaceutical Co., Ltd., curing accelerator), 0.1 parts of San-Aid SI-B5 (Sanshin Chemical Co., Ltd., curing accelerator), 99.2 parts of toluene as a solvent, and 49.6 parts of tetrahydrofuran. The mixture was heated at 110°C for 10 minutes in a nitrogen atmosphere, and then heated at 220°C for 1 hour to obtain a cured product.

[0135] [Reference example 2] A mixture of 0.5 parts of compound (C3) obtained in Synthesis Example 3, 50 parts of NC-3000 (biphenylaralkyl epoxy resin manufactured by Nippon Kayaku Co., Ltd.), 10 parts of MIZ-001 (maleimide resin manufactured by Nippon Kayaku Co., Ltd.), 5 parts of STR-2000 (styrene resin manufactured by Nippon Kayaku Co., Ltd.), 45 parts of KAYARAD R-684 (acrylate resin manufactured by Nippon Kayaku Co., Ltd.), 1 part of Irgacure OXE-04 (photopolymerization initiator manufactured by BASF), and 1 part of Irgacure 290 (photopolymerization initiator manufactured by BASF) was applied to a PET film to a thickness of 100 μm. A PET film was also attached to the side not in contact with the film, and the mixture was irradiated with 3000 mJ / cm using a high-pressure mercury lamp (365 nm). 2 A cured product could be obtained by irradiating the composition with ultraviolet light. [Industrial Applicability]

[0136] The base generator of the present invention can be used, for example, as a latent curing accelerator for epoxy compounds. Because of its excellent storage stability, refrigeration of the composition is unnecessary, and because of its excellent curing properties, it can be cured at low temperatures. Therefore, the base generator of the present invention is useful for resin encapsulation of various electric and electronic components and semiconductor components. This application claims priority based on Japanese Patent Application No. 2024-118040, filed July 23, 2024, and Japanese Patent Application No. 2024-206115, filed November 27, 2024.

Claims

1. A base generator represented by the following formula (a), which comprises an imidazolium cation and an anion residue of an organic acid or an inorganic acid: 【Chemistry 1】 In formula (a), A represents a divalent group having 1 to 8 carbon atoms which may contain a heteroatom; R 1 is a methyl group or a phenyl group, R 2 is a methyl group or a benzyl group, R 3 and R 4 are hydrogen atoms, R ５ ~R ９ each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms which may have a substituent, a halogen atom, a hydroxyl group, an alkoxy group, a mercapto group, a sulfide group, a silyl group, a silanol group, a nitro group, a nitroso group, a cyano group, a sulfino group, a sulfo group, a sulfonato group, a phosphino group, a phosphinyl group, a phosphono group, a phosphonato group, an amino group, or an ammonio group; R ５ and R ６ , R ６ and R ７ , R ７ and R ８ , R ８ and R ９ may be bonded to each other to form a ring structure, X － is the anionic residue of an organic or inorganic acid.

2. The base generator according to claim 1, wherein A in formula (a) is an unsubstituted divalent hydrocarbon group having 1 to 8 carbon atoms, or a divalent group having 1 to 8 carbon atoms containing a carbonyl group, an ether group, an ester group, an amide group, or a sulfide group.

3. The anionic residue X in the formula (a) － The base generator according to claim 1 , wherein contains a halogen atom, a boron atom, or a silicon atom.

4. The anionic residue X in the formula (a) － The base generator according to claim 1, wherein the base generator is represented by the following formula (b-1): 【Chemistry 2】 In formula (b-1), R １０ ~R １３ each independently represents a linear alkyl group having 1 to 16 carbon atoms, a branched alkyl group having 3 to 16 carbon atoms, or a substituted or unsubstituted aromatic ring having 6 to 16 carbon atoms.

5. R in the formula (b-1) １０ ~R １３ The base generator according to claim 4, wherein each of the is a phenyl group.

6. A base generator represented by the following formula (a), which comprises an imidazolium cation and an anion residue of an organic acid or an inorganic acid: 【Transformation 3】 In formula (a), A represents a divalent group having 1 to 8 carbon atoms which may contain a heteroatom; R １ ~R ４ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms which may have a substituent, an aryl group having 6 to 20 carbon atoms which may have a substituent, or an alkylaryl group having 7 to 20 carbon atoms which may have a substituent, and R １ and R ２ , R ２ and R ３ , R ３ and R ４ may be bonded to each other to form a ring structure, R ５ ~R ９ each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms which may have a substituent, a halogen atom, a hydroxyl group, an alkoxy group, a mercapto group, a sulfide group, a silyl group, a silanol group, a nitro group, a nitroso group, a cyano group, a sulfino group, a sulfo group, a sulfonato group, a phosphino group, a phosphinyl group, a phosphono group, a phosphonato group, an amino group, or an ammonio group; R ５ and R ６ , R ６ and R ７ , R ７ and R ８ , R ８ and R ９ may be bonded to each other to form a ring structure, X － is an anionic residue represented by the following formula (b-2), in which Y 1 and Y 2 are organic groups and may be the same or different from each other. Z 1 represents an organic group having a substituted or unsubstituted aromatic ring or heterocycle, or a substituted or unsubstituted aliphatic group. 【Chemistry 4】

7. A base generator represented by the following formula (a), which comprises an imidazolium cation and an anion residue of an organic acid or an inorganic acid: 【Transformation 5】 In formula (a), A represents a divalent group having 1 to 8 carbon atoms which may contain a heteroatom; R １ ~R ４ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms which may have a substituent, an aryl group having 6 to 20 carbon atoms which may have a substituent, or an alkylaryl group having 7 to 20 carbon atoms which may have a substituent, and R １ and R ２ , R ２ and R ３ , R ３ and R ４ may be bonded to each other to form a ring structure, R ５ ~R ９ each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms which may have a substituent, a halogen atom, a hydroxyl group, an alkoxy group, a mercapto group, a sulfide group, a silyl group, a silanol group, a nitro group, a nitroso group, a cyano group, a sulfino group, a sulfo group, a sulfonato group, a phosphino group, a phosphinyl group, a phosphono group, a phosphonato group, an amino group, or an ammonio group; R ５ and R ６ , R ６ and R ７ , R ７ and R ８ , R ８ and R ９ may be bonded to each other to form a ring structure, X － is an anionic residue represented by the following formula (b-3) or (b-4). 【Transformation 6】 【Transformation 7】

8. A curable resin composition containing the base generator according to claim 1 , 6 or 7 .

9. The curable resin composition according to claim 8, further comprising an epoxy resin.

10. The curable resin composition according to claim 9, further comprising a curing agent.

11. The curable resin composition according to claim 8, further comprising at least one selected from the group consisting of maleimide compounds, polyphenylene ether compounds, compounds having an ethylenically unsaturated bond, cyanate compounds, polybutadiene and modified products thereof, polystyrene and modified products thereof, and polyethylene and modified products thereof.

12. The curable resin composition according to claim 8, further comprising at least one selected from the group consisting of a thermal polymerization initiator, a photopolymerization initiator, an anionic curing accelerator, and a cationic curing accelerator.

13. The curable resin composition according to claim 8, which is used for any one of a semiconductor encapsulant, an adhesive, an adhesive film, a prepreg, an interlayer insulating material, and a thermally conductive and heat-dissipating material.

14. A cured product of the curable resin composition according to claim 8.

15. A printed wiring board comprising the cured product according to claim 14.

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