Epoxy resin composition, cured epoxy resin composition, prepreg, laminate, printed circuit board, method for decomposing cured epoxy resin composition

Abstract

It exhibits excellent solubility in solvents and epoxy resins, provides excellent processability and moldability in resin compositions with epoxy resins, and offers a cured product with excellent low dielectric properties, low water absorption properties, easy peelability, and easy decomposition. [Solution] An epoxy resin composition characterized by comprising a curing agent containing a compound represented by the following formula (1) and an epoxy resin. [Formula 1] TIFF2026106065000012.tif29151 [In the formula, R 1 and R 2 These independently represent organic groups, Ar 1 and Ar 2 [where n independently represents an aromatic group that may have substituents (except phenolic hydroxyl groups), and n and m independently represent integers of 1 or more.]

Description

[Technical Field]

[0001] The present invention relates to an epoxy resin composition comprising a curing agent and an epoxy resin. More specifically, the present invention relates to an epoxy resin composition that provides a cured product that is easy to handle, has excellent processability and moldability, has excellent dielectric properties, and is also easily disassembled. [Background technology]

[0002] Epoxy resin compositions, consisting of epoxy resin and a curing agent, are used in a wide range of applications, including paints, civil engineering adhesives, castings, electrical and electronic materials, and film materials, due to their excellent adhesion, flexibility, heat resistance, chemical resistance, insulation, and curing reaction. On the other hand, cured products obtained from epoxy resin compositions are difficult to decompose; for example, adhesives and electronic materials using epoxy resin are not easily disassembled once cured. In recent years, from the perspective of environmental protection and resource recycling, there has been a growing demand for curing agents that exhibit stable strength, heat resistance, and adhesion when in use, but can be easily peeled off and decomposed by specific stimuli when not needed.

[0003] As a curing agent that can be easily dismantled, curing agents containing a diacylhydrazine skeleton have been reported. Patent Document 1 discloses a bisphenol curing agent having a diacylhydrazine skeleton. In the epoxy resin composition described in that document, the diacylhydrazine skeleton is well decomposed by an oxidizing agent such as sodium hypochlorite.

[0004] However, the bisphenol curing agent having a diacylhydrazine skeleton disclosed in the above-mentioned patent document has a high melting point and poor solubility in solvents and epoxy resins, resulting in poor handling and processability of the resin composition. Poor uniformity of the epoxy resin composition can easily lead to curing failures, reducing the reliability of the cured product, such as decreased chemical resistance and strength.

[0005] Furthermore, in recent years, information devices have been rapidly becoming smaller and more high-performance. Consequently, epoxy resin compositions used in the fields of semiconductors and electronic components are required to have low dielectric properties and low moisture absorption properties to accommodate the thinning and high functionality of substrates. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 5580109 [Overview of the project] [Problems that the invention aims to solve]

[0007] The present invention aims to provide an epoxy resin composition that exhibits excellent solubility in solvents and epoxy resins, as well as excellent workability and moldability, and to provide a cured product that has excellent dielectric properties, low hygroscopicity, and is easily peelable and easily disassembled. Another object of the present invention is to provide a method for decomposing such a cured epoxy resin composition by decomposition treatment such as oxidative decomposition. [Means for solving the problem]

[0008] As a result of diligent research to solve the above problems, the present inventors have found that a curing agent containing a diacylhydrazine skeleton having an active ester group provides excellent processability and moldability in resin compositions with epoxy resins, and that it is possible to provide a cured product with low dielectric properties, low hygroscopicity, easy peelability, and easy decomposition, thus completing the present invention.

[0009] In other words, the present invention is an epoxy resin composition characterized by comprising a curing agent containing a compound represented by the following formula (1) and an epoxy resin. [ka] [In the formula, R 1 and R 2 These independently represent organic groups, Ar 1 and Ar 2represents an aromatic group which may independently have a substituent (excluding phenolic hydroxy group), and n and m each independently represent an integer of 1 or more.

Advantages of the Invention

[0010] In the epoxy resin composition according to the present invention, by using the compound represented by the above formula (1) as a curing agent, it has excellent solubility in a solvent and an epoxy resin, gives excellent processing moldability in a resin composition with an epoxy resin, and can provide a cured product excellent in low dielectric properties, low moisture absorption, easy peeling property, and easy decomposability. Further, a method for decomposing the cured product of such an epoxy resin composition by decomposition treatment can be provided.

Modes for Carrying Out the Invention

[0011] The epoxy resin composition of the present disclosure contains, as essential components, an epoxy resin and a curing agent containing a compound having a structure represented by the following formula (1). With the structure of the following formula (1), it shows solubility in a solvent and an epoxy resin, and an epoxy resin composition excellent in uniformity can be obtained, and it has excellent processing moldability. Further, a cured product obtained by curing the epoxy resin composition of the present invention exhibits excellent dielectric properties and low moisture absorption, and in addition, can exhibit easy peeling property and easy disintegration property. Therefore, disassembly at the time of discarding a product and subsequent recycling are easy.

[0012]

Chemical formula

[0013] In the above formula (1), n and m each independently represent an integer of 1 or more, and are preferably an integer of 1 to 3. From the viewpoint of storage stability in the resin composition, n and m are more preferably 1 or 2 respectively and independently.

[0014] In the above formula (1), Ar 1 , Ar 2 each independently represents an aromatic group which may have a substituent, Ar 1 and Ar 2may be the same or different.

[0015] Examples of the aromatic group include groups derived from aromatic hydrocarbons and aromatic heterocycles. Examples of the aromatic hydrocarbon group include those derived from benzene, pentalene, indene, naphthalene, anthracene, azulene, acenaphthene, phenalene, fluorene, phenanthrene, biphenyl, terphenyl, quarterphenyl, pyrene, 9,9-diphenylfluorene, 9,9'-spirobi[fluorene], 9,9-dialkylfluorene, and the like. Examples of the aromatic heterocyclic group include pyridine, pyrazine, pyridazine, pyrimidine, triazine, quinoline, isoquinoline, quinoxaline, quinazoline, naphthyridine, acridine, phenazine, benzoquinoline, benzoisoquinoline, phenanthridine, phenanthroline, benzoquinone, coumarin, fluorenone, furan, thiophene, benzofuran, benzothiophene, dibenzofuran, dibenzothiophene, pyrrole, indole, carbazole, imidazole, benzimidazole, pyrazole, indazole, oxazole, isoxazole, benzoxazole, benzisoxazole, thiazole, isothiazole, benzothiazole, benzisothiazole, imidazolinone, benzimidazolinone, imidazopyridine, imidazopyrimidine, azadibenzofuran, azacarbazole, azadibenzothiophene, diazadibenzofuran, diazacarbazole, diazadibenzothiophene, xanthone, thioxanthone, and the like.

[0016] Ar 1 and Ar 2 When the aromatic group of has a substituent, examples of the substituent include, for example, an alkyl group, an alkoxy group, a halogen atom (which may be any of a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an amino group, an acyl group, and the like, but are not limited thereto. However, from the viewpoint of deterioration of processing and molding properties, the phenolic hydroxy group is excluded from the substituent.

[0017] From the viewpoint of realizing a resin composition excellent in both processing and molding properties and dielectric properties, Ar1 Ar 2 The number of carbon atoms in the aromatic group is preferably 6 to 14, and more preferably 6 to 10. Examples of the aromatic group include a phenyl group, a naphthyl group, and an anthracenyl group.

[0018] R 1 , R 2 R indicates an organic group. 1 and R 2 These may be the same or different. Examples of organic groups include linear or branched alkyl groups, linear or branched alkenyl groups, aromatic hydrocarbon groups, and aromatic heterocyclic groups. 1 and R 2 The organic group may be unsubstituted or may have substituents (excluding phenolic hydroxyl groups).

[0019] Examples of alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, tert-pentyl group, neopentyl group, 1,2-dimethylpropyl group, n-hexyl group, isohexyl group, 1,3-dimethylbutyl group, 1-isopropylpropyl group, 1,2-dimethylbutyl group, n-heptyl group, 1,4-dimethylpentyl group, 3-ethylpentyl group, and 2-methyl-1-isopropylpropyl group. Examples include pyr group, 1-ethyl-3-methylbutyl group, n-octyl group, 2-ethylhexyl group, 3-methyl-1-isopropylbutyl group, 2-methyl-1-isopropyl group, 1-tert-butyl-2-methylpropyl group, n-nonyl group, 3,5,5-trimethylhexyl group, n-decyl group, isodecyl group, n-undecyl group, 1-methyldecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, and n-octadecyl group.

[0020] Examples of alkenyl groups include allyl, 1-propenyl, 2-butenyl, 1,3-butadienyl, 2-pentenyl, and isopropenyl groups.

[0021] Aromatic hydrocarbon groups include groups derived from aromatic hydrocarbons such as benzene (benzene ring), pentalene, indene, naphthalene, anthracene, azulene, acenaphthene, phenalene, fluorene, phenanthrine, biphenyl, terphenyl, quaterphenyl, pyrene, 9,9-diphenylfluorene, 9,9'-spirobio[fluorene], and 9,9-dialkylfluorene.

[0022] Aromatic heterocyclic groups include pyridine, pyrazine, pyridazine, pyrimidine, triazine, quinoline, isoquinoline, quinoxaline, quinazoline, naphthyridine, acridine, phenazine, benzoquinoline, benzoisoquinoline, phenanthridine, phenanthroline, benzoquinone, coumarin, fluorenone, furan, thiophene, benzofuran, benzothiophene, dibenzofuran, dibenzothiophene, pyrrole, indole, carbazole, imidazole, benzimidazole, and pyrazoline. Examples of groups derived from heterocyclic aromatic compounds include thiazole, indazole, oxazole, isoxazole, benzoxazole, benzoisoxazole, thiazole, isothiazole, benzothiazole, benzoisothiazole, imidazolinone, benzimidazolinone, imidazopyridine, imidazopyrimidine, azadibenzofuran, azacarbazole, azadibenzothiophene, diazadibenzofuran, diazacarbazole, diazadibenzothiophene, xanthone, and thioxanthone.

[0023] R 1 and R 2 When the organic group has substituents, the substituents are not particularly limited except for phenolic hydroxyl groups, but examples include alkyl groups, alkoxy groups, halogen atoms (which may be fluorine, chlorine, bromine, or iodine atoms), amino groups, acyl groups, etc. 1 and R 2If an organic group has two or more substituents, they may be the same or different.

[0024] R 1 and R 2 From the viewpoint of workability, alkyl groups or alkenyl groups are preferred, and from the viewpoint of heat resistance, aromatic hydrocarbon groups or aromatic heterocyclic groups are preferred. Of these, from the viewpoint of balancing workability and the heat resistance of the cured product, R 1 and R 2 The C1-C12 alkyl group or C6-C14 aromatic hydrocarbon group is preferred, more preferably C1-C6 alkyl group or C6-C10 aromatic hydrocarbon group, and even more preferably C1-C3 alkyl group or C6-C10 aromatic hydrocarbon group.

[0025] The compounds of this disclosure can be produced by known methods. For example, they can be produced by referring to the methods of the following examples. Specifically, an aromatic compound having an ester group and a carboxyl group (e.g., 3-acetoxybenzoic acid) is reacted with a chloride acylating agent (e.g., thionyl chloride) to obtain a compound (intermediate A) in which the carboxyl group is converted to a -COCl group. This intermediate A can then be reacted with hydrazine.

[0026] In addition, the epoxy resin composition of the present invention is a resin composition comprising a curing agent containing the compound represented by formula (1) and an epoxy resin. The cured product obtained by curing the epoxy resin composition of the present invention exhibits excellent strength, heat resistance, adhesion, and other functions similar to general epoxy resin cured products, but can be easily decomposed and disassembled by appropriate treatment (for example, oxidative decomposition).

[0027] As the epoxy resin used to obtain the epoxy resin composition of the present invention, one or more types of epoxy resins may be used in combination as needed.

[0028] Epoxy resins preferably have two or more epoxy groups in their molecule, such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, bisphenol Z type epoxy resin, bisphenol fluorene type epoxy resin, diphenyl sulfide type epoxy resin, diphenyl ether type epoxy resin, naphthalene type epoxy resin, hydroquinone type epoxy resin, resorcinol type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, and alkyl novolac. Examples of epoxy resins include various types of epoxy resins such as styrene-type epoxy resins, styrene-phenol novolac type epoxy resins, bisphenol novolac type epoxy resins, naphthol novolac type epoxy resins, phenol aralkyl type epoxy resins, β-naphthol aralkyl type epoxy resins, naphthalenediol aralkyl type epoxy resins, α-naphthol aralkyl type epoxy resins, biphenyl aralkylphenol type epoxy resins, biphenyl type epoxy resins, triphenylmethane type epoxy resins, dicyclopentadiene type epoxy resins, alkylene glycol type epoxy resins, and aliphatic cyclic epoxy resins.

[0029] In the epoxy resin composition of the present invention, the molar ratio of active hydrogen groups of the curing agent to 1 mole of epoxy groups of the total epoxy resin is preferably 0.2 to 1.5 moles, more preferably 0.3 to 1.4 moles, even more preferably 0.5 to 1.3 moles, and particularly preferably 0.8 to 1.2 moles. If the ratio falls outside this range, curing may be incomplete, and good cured properties may not be obtained.

[0030] In this invention, an active hydrogen group refers to a functional group having active hydrogen that reacts with an epoxy group (including functional groups having latent active hydrogen that generates active hydrogen through hydrolysis, etc., and functional groups that exhibit equivalent curing activity). Specifically, examples include acid anhydride groups, carboxyl groups, amino groups, phenolic hydroxyl groups, and active ester groups. Regarding active hydrogen groups, 1 mole of carboxyl groups or phenolic hydroxyl groups is calculated as 1 mole, and 2 moles of amino groups (NH2). Furthermore, if the active hydrogen group is not clearly defined, the active hydrogen equivalent can be determined by measurement. For example, the active hydrogen equivalent of the curing agent used can be determined by reacting a monoepoxy resin such as phenyl glycidyl ether, whose epoxy equivalent is known, with a curing agent whose active hydrogen equivalent is unknown, and measuring the amount of monoepoxy resin consumed.

[0031] As a curing agent, in addition to the compound represented by formula (1), one or more other commonly used curing agents such as various phenolic resins, acid anhydrides, amines, hydrazides, and acidic polyesters may be used in combination as needed. When these other curing agents are used in combination, the amount of the other curing agents used is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 50% by mass or less of the total curing agent. If the proportion of the curing agents used in combination is too high, the decomposition and disintegration properties of the cured product tend to decrease. That is, the amount of the compound represented by formula (1) is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 50% by mass or more of the total curing agent.

[0032] Specific examples of phenolic resin curing agents that can be used in the epoxy resin composition of the present invention include bisphenols such as bisphenol A, bisphenol F, bisphenol C, bisphenol K, bisphenol Z, bisphenol S, tetramethylbisphenol A, tetramethylbisphenol F, tetramethylbisphenol S, tetramethylbisphenol Z, dihydroxydiphenyl sulfide, and 4,4'-thiobis(3-methyl-6-t-butylphenol); dihydroxybenzenes such as catechol, resorcinol, methylresorcinol, hydroquinone, monomethylhydroquinone, dimethylhydroquinone, trimethylhydroquinone, mono-t-butylhydroquinone, and di-t-butylhydroquinone; hydroxynaphthalenes such as dihydroxynaphthalene, dihydroxymethylnaphthalene, and trihydroxynaphthalene; phosphorus-containing phenolic curing agents such as LC-950PM60 (manufactured by Shin-AT&C); and Showol BRG-555 (manufactured by Aica Kogyo Co., Ltd.). Examples include phenolic compounds known as novolac phenolic resins, such as phenol novolac resins, cresol novolac resins such as DC-5 (manufactured by Nippon Steel Chemical & Material Co., Ltd.), aromatic modified phenol novolac resins, bisphenol A novolac resins, trishydroxyphenylmethane type novolac resins such as Resitopp TPM-100 (manufactured by Gun-ei Chemical Industry Co., Ltd.), naphthol novolac resins, condensates of phenols, naphthols and / or bisphenols with aldehydes, condensates of phenols, naphthols and / or bisphenols with xylylene glycol, condensates of phenols and / or naphthols with isopropenylacetophenone, reaction products of phenols, naphthols and / or bisphenols with dicyclopentadiene, and condensates of phenols, naphthols and / or bisphenols with biphenyl crosslinking agents. From the standpoint of availability, phenol novolac resins, dicyclopentadiene-type phenolic resins, trishydroxyphenylmethane-type novolac resins, aromatically modified phenol novolac resins, etc., are preferred.

[0033] In the case of novolacphenol resins, examples of phenols include phenol, cresol, xylenol, butylphenol, amylphenol, nonylphenol, butylmethylphenol, trimethylphenol, and phenylphenol. Examples of naphthols include 1-naphthol and 2-naphthol, and other bisphenols include those listed above. Examples of aldehydes include formaldehyde, acetaldehyde, propylaldehyde, butyraldehyde, valeraldehyde, caproaldehyde, benzaldehyde, chloraldehyde, bromaldehyde, glyoxal, malonaldehyde, succinaldehyde, glutaraldehyde, adipinealdehyde, pimelinaldehyde, sebacinaldehyde, acrolein, crotonaldehyde, salicylaldehyde, phthalaldehyde, and hydroxybenzaldehyde. Examples of biphenyl-based crosslinking agents include bis(methylol)biphenyl, bis(methoxymethyl)biphenyl, bis(ethoxymethyl)biphenyl, and bis(chloromethyl)biphenyl.

[0034] Examples of acid anhydride-based curing agents include methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, pyromellitic anhydride, phthalic anhydride, trimellitic anhydride, and methylnadic acid.

[0035] Examples of amine-based curing agents include amine compounds such as diethylenetriamine, triethylenetetramine, metaxylenediamine, isophoronediamine, diaminodiphenylmethane, diaminodiphenylsulfone, diaminodiphenyl ether, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, dicyandiamide, and polyamidoamine, which are condensates of acids such as dimer acids and polyamines.

[0036] Furthermore, from the viewpoint of low dielectric constant and low dielectric loss tangent, active ester-based curing agents are preferred. For example, compounds having two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds, are preferred. Among these, phenol esters obtained by reacting a carboxylic acid compound with an aromatic compound having a phenolic hydroxyl group are more preferred. Specific examples of carboxylic acid compounds include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of aromatic compounds having a phenolic hydroxyl group include catechol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadienyldiphenol, and phenol novolac.

[0037] Other curing agents include, specifically, phosphine compounds such as triphenylphosphine, phosphonium salts such as tetraphenylphosphonium bromide, imidazoles such as 2-methylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, and 1-cyanoethyl-2-methylimidazole, imidazole salts which are salts of imidazoles with trimellitic acid, isocyanuric acid, or boron, etc., quaternary ammonium salts such as trimethylammonium chloride, diazabicyclo compounds, salts of diazabicyclo compounds with phenols or phenol novolac resins, etc., complex compounds of boron trifluoride with amines or ether compounds, etc., aromatic phosphonium, or iodonium salts.

[0038] A curing accelerator may be used in the epoxy resin composition as needed. The inclusion of a curing accelerator can accelerate the curing reaction between the epoxy resin and the curing agent, allowing for efficient adjustment of the curing time and curing temperature. As the curing accelerator, it is preferable to use one or more selected from conventionally known amine-based curing accelerators, organophosphorus-based curing accelerators, and imidazole-based curing accelerators. When using a curing accelerator, the amount used is preferably 0.02 to 5 parts by mass per 100 parts by mass of the epoxy resin component in the epoxy resin composition of the present invention.

[0039] The epoxy resin composition may be used with an organic solvent or reactive diluent to adjust its viscosity.

[0040] Examples of organic solvents include amides such as N,N-dimethylformamide and N,N-dimethylacetamide; ethers such as ethylene glycol monomethyl ether, dimethoxydiethylene glycol, ethylene glycol diethyl ether, diethylene glycol diethyl ether, and triethylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohols such as methanol, ethanol, 1-methoxy-2-propanol, 2-ethyl-1-hexanol, benzyl alcohol, ethylene glycol, propylene glycol, butyl diglycol, and pine oil; and vinegar. Examples of acetate esters such as butyl acid, methoxybutyl acetate, methyl cellosolve acetate, cellosolve acetate, ethyl diglycol acetate, propylene glycol monomethyl ether acetate, carbitol acetate, and benzyl alcohol acetate; benzoic acid esters such as methyl benzoate and ethyl benzoate; cellosolves such as methyl cellosolve, cellosolve, and butyl cellosolve; carbitols such as methyl carbitol, carbitol, and butyl carbitol; aromatic hydrocarbons such as benzene, toluene, and xylene; and dimethyl sulfoxide, acetonitrile, and N-methylpyrrolidone, but are not limited to these.

[0041] Examples of reactive diluents include, but are not limited to, monofunctional glycidyl ethers such as allyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and tolyl glycidyl ether; difunctional glycidyl ethers such as resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, and propylene glycol diglycidyl ether; polyfunctional glycidyl ethers such as glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, trimethylolethane polyglycidyl ether, and pentaerythritol polyglycidyl ether; glycidyl esters such as neodecanoic acid glycidyl ester; and glycidylamines such as phenyl diglycidylamine and tolyl diglycidylamine.

[0042] These organic solvents or reactive diluents are preferably used individually or in combination in the epoxy resin composition in an amount of 90% by mass or less, and the appropriate type and amount are selected as appropriate depending on the application. For example, in printed circuit board applications, polar solvents with a boiling point of 160°C or less, such as methyl ethyl ketone, acetone, and 1-methoxy-2-propanol, are preferred, and the amount used is preferably 40 to 80% by mass. In adhesive film applications, for example, ketones, acetate esters, carbitols, aromatic hydrocarbons, dimethylformamide, dimethylacetamide, and N-methylpyrrolidone are preferred, and the amount used is preferably 30 to 60% by mass.

[0043] The epoxy resin composition may contain other thermosetting resins or thermoplastic resins to the extent that it does not impair the properties. Examples include, but are not limited to, phenolic resins, acrylic resins, petroleum resins, indene resins, coumarone indene resins, phenoxy resins, polyurethane resins, polyester resins, polyamide resins, polyimide resins, polyamide-imide resins, polyetherimide resins, polyphenylene ether resins, modified polyphenylene ether resins, polyethersulfone resins, polysulfone resins, polyetheretherketone resins, polyphenylene sulfide resins, and polyvinyl formal resins.

[0044] Various known flame retardants can be used in the epoxy resin composition to improve the flame retardancy of the resulting cured product. Examples of usable flame retardants include halogen-based flame retardants, phosphorus-based flame retardants, nitrogen-based flame retardants, silicone-based flame retardants, inorganic flame retardants, and organometallic salt-based flame retardants. From an environmental standpoint, halogen-free flame retardants are preferred, and phosphorus-based flame retardants are particularly preferred. These flame retardants may be used individually or in combination of two or more types.

[0045] Phosphorus-based flame retardants can be either inorganic phosphorus compounds or organophosphorus compounds. Examples of inorganic phosphorus compounds include ammonium phosphates such as red phosphorus, monoammonium phosphate, diammonium phosphate, triammonium phosphate, and polyammonium phosphate, as well as inorganic nitrogen-containing phosphorus compounds such as phosphate amides. Examples of organophosphorus compounds include aliphatic phosphate esters, phosphate ester compounds, condensed phosphate esters such as PX-200 (manufactured by Daihachi Chemical Industry Co., Ltd.), phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phospholane compounds, and organic nitrogen-containing phosphorus compounds, as well as metal salts of phosphinic acid, cyclic organophosphorus compounds such as 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(2,5-dihydrooxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide, and 10-(2,7-dihydrooxynaphthyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide, and derivatives obtained by reacting these with compounds such as epoxy resins and phenolic resins, such as phosphorus-containing epoxy resins and phosphorus-containing curing agents.

[0046] The amount of flame retardant added is appropriately selected depending on the type of phosphorus-based flame retardant, the components of the epoxy resin composition, and the desired degree of flame retardancy. For example, the phosphorus content in the organic components (excluding organic solvents) of the epoxy resin composition is preferably 0.2 to 4% by mass, more preferably 0.4 to 3.5% by mass, and even more preferably 0.6 to 3% by mass. If the phosphorus content is too low, it may be difficult to ensure flame retardancy, and if it is too high, it may adversely affect the heat resistance. Furthermore, when using phosphorus-based flame retardants, flame retardant additives such as magnesium hydroxide may be used in combination.

[0047] Fillers may be used in epoxy resin compositions as needed. Specifically, examples include fused silica, crystalline silica, alumina, silicon nitride, aluminum hydroxide, boehmite, magnesium hydroxide, talc, mica, calcium carbonate, calcium silicate, calcium hydroxide, magnesium carbonate, barium carbonate, barium sulfate, boron nitride, carbon, carbon fiber, glass fiber, alumina fiber, silica-alumina fiber, silicon carbide fiber, polyester fiber, cellulose fiber, aramid fiber, ceramic fiber, fine particle rubber, thermoplastic elastomer, and pigments. Generally, the reason for using fillers is to improve impact resistance. In addition, when metal hydroxides such as aluminum hydroxide, boehmite, and magnesium hydroxide are used, they act as flame retardant aids, improving flame retardancy. The amount of these fillers in the epoxy resin composition (excluding organic solvents) is 1 to 80% by mass, more preferably 5 to 70% by mass. If the amount is too high, the adhesion required for laminate applications may decrease, and the cured product may become brittle, resulting in insufficient mechanical properties. Furthermore, if the amount of filler used is too small, the intended effects of the filler, such as improved impact resistance of the cured product, may not be realized.

[0048] When epoxy resin compositions are used to form plate-shaped substrates, fibrous materials are preferred as fillers in terms of dimensional stability and flexural strength. More preferably, glass fiber substrates are made by weaving glass fibers into a mesh.

[0049] The epoxy resin composition may further contain radionuclide additives such as silane coupling agents, antioxidants, mold release agents, defoaming agents, emulsifiers, thixotropy-inducing agents, smoothing agents, flame retardants, and pigments, as needed. The amount of these additives added is preferably in the range of 0.01 to 20% by mass relative to the epoxy resin composition.

[0050] The epoxy resin composition can be used to create prepregs for use in printed circuit boards and the like by impregnating it into a fibrous substrate. The fibrous substrate can be inorganic fibers such as glass, or woven or nonwoven fabrics of organic fibers such as polyester resin, polyamine resin, polyacrylic resin, polyimide resin, or aromatic polyamide resin, but is not limited to these. The method for producing a prepreg from an epoxy resin composition is not particularly limited, but for example, it can be obtained by impregnating the epoxy resin composition into a resin varnish prepared by adjusting the viscosity with an organic solvent, and then heating and drying it to partially cure (B-stage) the resin component. For example, it can be heated and dried at 100 to 200°C for 1 to 40 minutes. Here, the amount of resin in the prepreg is preferably 30 to 80% by mass.

[0051] Furthermore, while the curing method for laminates commonly used in the manufacture of printed circuit boards can be used to cure prepregs, it is not limited to this method. For example, when forming a laminate using prepregs, one or more prepregs are stacked, metal foil is placed on one or both sides to form a laminate, and this laminate is heated and pressurized to integrate the layers. Here, single, alloy, or composite metal foils of copper, aluminum, brass, nickel, etc., can be used as the metal foil. Then, the prepreg is cured by pressurizing and heating the created laminate to obtain a laminate. At that time, the heating temperature is 160~220°C and the pressurizing pressure is 50~500 N / cm 2 Preferably, the heating and pressurizing time is set to 40 to 240 minutes, which allows for obtaining the desired cured product. If the heating temperature is too low, the curing reaction will not proceed sufficiently, and if it is too high, the decomposition of the epoxy resin composition may begin. Also, if the pressurizing pressure is too low, air bubbles may remain inside the resulting laminate, which may reduce its electrical properties, and if it is too high, the resin may flow before curing, which may prevent obtaining a cured product of the desired thickness. Furthermore, if the heating and pressurizing time is too short, the curing reaction may not proceed sufficiently, and if it is too long, thermal decomposition of the epoxy resin composition in the prepreg may occur, which is undesirable.

[0052] Epoxy resin compositions can be cured in the same way as known epoxy resin compositions to obtain cured epoxy resin products. Methods for obtaining cured products can be the same as those for known epoxy resin compositions, and methods such as casting, injection, potting, dipping, drip coating, transfer molding, compression molding, etc., or lamination of resin sheets, resin-coated copper foil, prepregs, etc., followed by heating, pressing, and curing to form laminates are preferably used. The curing temperature is usually 100-300°C, and the curing time is usually 1-5 hours, but this can be appropriately set depending on the components and their amounts in the epoxy resin composition.

[0053] The cured product of the epoxy resin composition of the present invention can take the form of a laminate, molded product, adhesive product, coating film, film, or the like.

[0054] Furthermore, as described above, the cured product of the epoxy resin composition of the present invention has easy peelability and easy decomposition properties due to the use of the compound represented by formula (1) as a curing agent, and can be easily decomposed by treatments such as oxidative decomposition, as can be seen in the examples described later. Oxidative decomposition is a more preferred embodiment. The decomposition agent that can be used for oxidative decomposition according to this disclosure is not particularly limited and can be appropriately selected depending on the composition of the epoxy resin composition. Specifically, examples include sodium hypochlorite and potassium permanganate. Of these, sodium hypochlorite is preferred from the viewpoint of ease of obtaining the reagent itself and the safety of the reagent itself. Here, the decomposition agent may be used as is, but from the viewpoint of ease of mixing and ease of decomposition, it is preferable to use it in the form of a solution, and it is more preferable to decompose the cured product by immersing it in an aqueous solution containing the decomposition agent. That is, in the preferred embodiment of the present invention, oxidative decomposition is preferably carried out using an aqueous solution of sodium hypochlorite.

[0055] When using an aqueous sodium hypochlorite solution for oxidative decomposition, the concentration of the aqueous sodium hypochlorite solution is not particularly limited, but is preferably 1 to 12% by mass, and more preferably 3 to 10% by mass.

[0056] Furthermore, the decomposition rate can be accelerated by mixing an organic solvent with an aqueous sodium hypochlorite solution. The organic solvent is not particularly limited, but water-soluble organic solvents such as acetone, tetrahydrofuran, dimethylformamide, and dimethylacetamide are preferred. The content of the organic solvent is preferably 1 to 50% by mass in the decomposition agent.

[0057] Furthermore, the oxidative decomposition conditions are not particularly limited and can be appropriately selected depending on the composition of the epoxy resin composition. The oxidative decomposition temperature is preferably, for example, 25 to 80°C, and more preferably 25 to 60°C. The oxidative decomposition time is preferably, for example, 1 to 72 hours. [Examples]

[0058] Next, the present invention will be described with reference to examples, but the present invention is not limited thereto. In each example, parts are all parts by weight. The physical properties in the examples were measured using the method described below.

[0059] 1) Solvent soluble 1.0 g of the sample was dissolved in 10 mL of tetrahydrofuran (THF), cyclohexanone (ANON), or N-methylpyrrolidone (NMP). The transparency of the dissolved sample was visually checked and classified as ○: transparent, ×: opaque or not completely dissolved to evaluate its compatibility.

[0060] 2) Solubility with epoxy resin 1.0 g of the sample was mixed with either bisphenol A type liquid epoxy resin (YD-128, manufactured by Nippon Steel Chemical & Material Co., Ltd.) or phenol novolac type liquid epoxy resin (YDPN-6300, manufactured by Nippon Steel Chemical & Material Co., Ltd.), and the mixture was heated to 180°C. Solubility was evaluated by visually checking the transparency of the sample at 180°C and classifying it as follows: ○: transparent, △: partially dissolved, ×: not dissolved.

[0061] 3) Dielectric properties Relative permittivity and dielectric loss tangent: These were evaluated by determining the relative permittivity and dielectric loss tangent at a frequency of 1 GHz using the capacitance method with a material analyzer (AGILENT Technologies) in accordance with IPC-TM-6502.5.5.9.

[0062] 4) Assessment of demolition feasibility A decomposition solution was prepared by mixing 30g of Kitchen Hyter (manufactured by Kao Corporation, an alkaline aqueous solution containing sodium hypochlorite, sodium hypochlorite concentration: approximately 6%) with 5g of THF. 1g of hardened material, formed into a plate shape, was immersed in the decomposition solution at room temperature for 48 hours. After immersion, the material was visually inspected. ○ indicated that the hardened material had completely decomposed within 48 hours, △ indicated that some decomposition, such as surface damage, was observed but the plate shape was maintained, and × indicated that it had not decomposed (no visible change).

[0063] 5) Water absorption rate Water absorption rate: Compliant with JIS K7209 standard. The test specimens used were the same samples used for measuring dielectric constant and dielectric loss tangent, and were measured after immersion in 23°C water for 24 hours.

[0064] Synthesis Example 1 300 g of 3-hydroxybenzoic acid, 443 g of acetic anhydride, and 11 g of pyridine were added to a 2 L reactor and reacted at 50°C for 4 hours. 500 g of pure water was added to the reaction solution to precipitate 3-acetoxybenzoic acid. After recovering the 3-acetoxybenzoic acid by suction filtration, it was further washed with pure water to obtain 3-acetoxybenzoic acid.

[0065] 100 g of 3-acetoxybenzoic acid, 99 g of thionyl chloride, 100 mL of dichloromethane, and 0.4 g of dimethylformamide obtained above were added to 500 mL of a reaction group and reacted at 60°C for 5 hours. Unreacted thionyl chloride and dichloromethane were removed by vacuum distillation to obtain 3-acetoxybenzoic acid chloride as the residue. Next, 100 mL of tetrahydrofuran was added to the reactor, and 43 g of hydrazine monohydrate was added dropwise over 60 minutes while cooling with ice water. After filtering the precipitated white solid, the solvent was removed from the filtrate using an evaporator. The remaining solid was washed with water to obtain compound A (active ester equivalent 178 g / eq.) represented by the following formula (2). [ka]

[0066] Synthesis Example 2 Using 100 g of 3,5-dihydroxybenzoic acid, 199 g of acetic anhydride, and 5 g of pyridine, 3,5-diacetoxybenzoic acid was synthesized by performing the same procedure as in Synthesis Example 1.

[0067] Using 100 g of 3,5-diacetoxybenzoic acid, 77 g of thionyl chloride, 0.1 g of dimethylformamide, 100 g of dichloromethane, 35 g of hydrazine monohydrate, and 100 mL of tetrahydrofuran obtained above, the same procedure as in Synthesis Example 1 was performed to obtain synthetic product B (active ester equivalent 118 g / eq.) represented by the following formula (3). [ka]

[0068] Synthesis Example 3 3-(benzoyloxy)benzoic acid was synthesized based on the method described in Journal of Physical Organic Chemistry, 2017, 30, 3. Next, using 100 g of 3-(benzoyloxy)benzoic acid, 74 g of thionyl chloride, 0.1 g of dimethylformamide, 100 g of dichloromethane, 31 g of hydrazine monohydrate, and 100 mL of tetrahydrofuran, the same procedure as in Synthesis Example 1 was performed to obtain synthetic product C (active ester equivalent 240 g / eq.) represented by the following formula (4). [ka]

[0069] Comparative Synthesis Example 1 50 g of compound A obtained in Synthesis Example 1, 58 g of potassium carbonate, and 300 g of methanol were placed in a 500 mL reactor and stirred for 6 hours. The precipitated solid was filtered and collected to obtain comparative compound D (phenol equivalent 136 g / eq.), represented by the following formula (5). [ka]

[0070] Reference example 1 The solvent solubility of compounds A-C and comparative compound D obtained in the synthesis examples was evaluated.

[0071] [Table 1]

[0072] Reference example 2 The solubility of synthetic compounds A-C and comparative compound D obtained in the synthesis examples with epoxy resin was evaluated.

[0073] [Table 2]

[0074] Tables 1 and 2 show that compounds A to C exhibit excellent solvent solubility and solubility with epoxy resins. Therefore, uniformity between the epoxy resin and the curing agent can be ensured by various methods, resulting in excellent processability and moldability.

[0075] Next, we will describe examples of cured products with epoxy resin, but the components used other than those mentioned above are as follows.

[0076] [Epoxy resin] YD-128: Bisphenol A type liquid epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., epoxy equivalent 187g / eq.) YDPN-6300: Phenolic novolac type liquid epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., epoxy equivalent 177g / eq.) [Hardening agent] BPA: Bisphenol A (manufactured by Nippon Steel Chemical & Material Co., Ltd., phenol equivalent 114g / eq.) [Curing catalyst] DMAP: N,N'-dimethyl-4-aminopyridine (manufactured by Tokyo Chemical Industry Co., Ltd.) 2E4MZ: 2-Ethyl-4-methylimidazole (manufactured by Shikoku Chemicals Co., Ltd.)

[0077] Example 1 Ten parts of epoxy resin YDPN-6300, 10.1 parts of compound A, and 0.1 parts of DMAP were mixed and reacted at 150°C for 5 minutes to obtain an epoxy resin composition. Furthermore, a cured product with a thickness of 2 mm was obtained by pressing for 90 minutes under the conditions of a vacuum of 0.5 kPa, a heating temperature of 220°C, and a press pressure of 2 MPa. A 2 mm spacer was used to adjust the thickness.

[0078] Examples 2-3, Comparative Example 1 A cured product was prepared by performing the same procedure as in Example 1, according to the amount (parts) of each raw material shown in Table 3.

[0079] [Table 3]

[0080] Examples 4-6 A hardened product was prepared by performing the same procedure as in Example 1, according to the amount (parts) of each raw material shown in Table 4. The disassembly properties were then evaluated.

[0081] [Table 4]

[0082] As shown in Table 3, in Examples 1-3, compounds A-C exhibited excellent solubility with epoxy resin, allowing for the production of cured products that possessed excellent dielectric properties, low hygroscopicity, and decomposability. In Comparative Example 1, poor compatibility with epoxy resin at 150°C prevented the curing reaction from proceeding, resulting in no cured product being obtained. Table 4 shows that decomposability decreases as the content of the compound represented by formula (1) in the curing agent decreases. [Industrial applicability]

[0083] The cured product of the epoxy resin composition of the present invention can be easily recycled by being easily disassembled when the product is discarded.

Claims

1. An epoxy resin composition characterized by comprising a curing agent containing a compound represented by the following formula (1) and an epoxy resin. 【Chemistry 1】 [In the formula, R １ and R ２ Ar independently represents an organic group. １ and Ar ２ [where n independently represents an aromatic group which may have substituents (except phenolic hydroxyl groups), and n and m independently represent integers of 1 or more.]

2. The epoxy resin composition according to claim 1, wherein the content of the compound represented by the above formula (1) among the curing agents is 30% by mass or more.

3. In the above formula (1), R １ and R ２ The epoxy resin composition according to claim 1, characterized in that is an alkyl group having 1 to 6 carbon atoms or a phenyl group which may have a substituent (except a phenolic hydroxyl group).

4. The epoxy resin composition according to claim 1, wherein in formula (1), n ​​or m is an integer from 1 to 3.

5. The epoxy resin composition according to claim 1, further comprising a curing catalyst.

6. The epoxy resin composition according to claim 5, wherein the curing catalyst comprises an amine-based curing catalyst or an imidazole-based curing catalyst.

7. A cured product characterized by being obtained by curing an epoxy resin composition according to any one of claims 1 to 6.

8. A prepreg characterized by using the epoxy resin composition described in any one of claims 1 to 6.

9. A laminate characterized by using the epoxy resin composition described in any one of claims 1 to 6.

10. A printed circuit board characterized by using the epoxy resin composition described in any one of claims 1 to 6.

11. A method for decomposing the cured product described in claim 7 by oxidative decomposition.

12. The method according to claim 11, wherein the oxidative decomposition is carried out using an aqueous solution of sodium hypochlorite.

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