Epoxy resin composition and cured product thereof

Abstract

Provided are: an epoxy resin composition that achieves both storage stability and reactivity at a high level; and a cured product thereof. Specifically, this epoxy resin composition comprises an epoxy resin (A) and a curing agent (B), wherein the curing agent (B) contains, as raw materials, a metal (b2) and a compound (b1) having one or more heteroatoms selected from the group consisting of nitrogen, oxygen, and phosphorus in a molecule; a carboxylic acid is included as the compound (b1); and the content of the curing agent (B) is 0.1-15 parts by mass with respect to 100 parts by mass of the epoxy resin (A).

Description

Epoxy resin composition and cured product thereof

[0001] This invention relates to epoxy resin compositions and cured products thereof.

[0002] Epoxy resins are used in a wide range of applications, such as paints, electrical and electronic insulating materials, and adhesives, because their cured products exhibit excellent mechanical, electrical, thermal, chemical resistance, and adhesive properties.

[0003] Because epoxy resins are difficult to cure on their own, one-component epoxy resin compositions are known in which a curing agent is pre-mixed with the epoxy resin and stored as a composition, and then heated or otherwise cured when needed. For example, Patent Document 1 discloses the use of a salt (white solid) formed by pre-mixing 1,8-diazabicyclo[5.4.0]undecene-7 (DBU) and benzoic acid as a latent curing agent. Patent Document 2 also discloses a latent curing agent composition that is liquid at room temperature, obtained by mixing an imidazole compound with a phosphite compound having one or more hydroxyl groups.

[0004] Japanese Patent Publication No. 2008-019350 Japanese Patent Publication No. 2010-168516

[0005] As described in Patent Document 1, most curing agents for epoxy resins are solid. In the case of solid curing agents, the curing reaction with the epoxy resin often proceeds when the curing agent dissolves. In other words, the melting point of the curing agent triggers the curing reaction. Therefore, when using a solid curing agent, there are issues with the dispersibility and handling of the curing agent when mixed with epoxy resin, as well as an increase in the viscosity of the composition.

[0006] On the other hand, liquid curing agents that are in liquid state at room temperature, such as the latent curing agent described in Patent Document 2, have also been developed. However, in epoxy resin curing systems, those with excellent storage stability have low reactivity (curability), and those with excellent reactivity have poor storage stability. In the composition disclosed in Patent Document 2, the curing reaction proceeds gradually with respect to temperature, resulting in low storage stability. In particular, with the recent rise of SDGs, there is a strong demand for improved storage stability from the perspective of reducing transportation and storage costs, and for improved reactivity from the perspective of increasing productivity. Therefore, the establishment of a curing technology in which the curing reaction proceeds rapidly at a specific temperature is desired.

[0007] Therefore, in view of the problems of the prior art described above, the present invention aims to provide an epoxy resin composition that achieves a high degree of both storage stability and reactivity. The present invention also aims to provide a cured product obtained by curing the epoxy resin composition.

[0008] As a result of diligent research, the inventors discovered that the above problems could be solved by adding a specific curing agent, and thus completed the present invention.

[0009] That is, the present invention relates to the following: 1. An epoxy resin composition comprising an epoxy resin (A) and a curing agent (B), wherein the curing agent (B) comprises a compound (b1) having one or more heteroatoms selected from the group consisting of nitrogen, oxygen, and phosphorus in its molecule and a metal (b2) as raw materials, wherein the compound (b1) includes carboxylic acids, and the content of the curing agent (B) is 0.1 to 15 parts by mass per 100 parts by mass of the epoxy resin (A). 2. The epoxy resin composition according to 1, wherein the viscosity of the curing agent (B) at 40°C is 20,000 mPa·s or less. 3. The epoxy resin composition according to 1 or 2, wherein the content of the curing agent (B) is 0.1 to 15 parts by mass as solid content per 100 parts by mass of solid content of the epoxy resin (A). 4. 1. The epoxy resin composition according to any one of 1 to 3, wherein the amount of carboxyl groups of the carboxylic acids is 0.8 to 20 moles per mole of metal atoms in the metal (b2). 5. The epoxy resin composition according to any one of 1 to 4, wherein the metal content in composition (B) is 1 to 30% by mass. 6. The epoxy resin composition according to any one of 1 to 5, wherein the molecular weight of compound (b1) is 500 or less. 7. The epoxy resin composition according to any one of 1 to 6, wherein the metal (b2) comprises one or more metals selected from the group consisting of potassium, cobalt, nickel, copper, and zinc. 8. The epoxy resin composition according to any one of 1 to 7, further comprising a curing agent (C). 9. The epoxy resin composition according to 8, wherein the metal (b2) comprises one or more metals selected from the group consisting of sodium, potassium, magnesium, calcium, strontium, barium, manganese, cobalt, nickel, copper, lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, and bismuth, and the curing agent (C) is dicyandiamide. 10. The epoxy resin composition according to 9, wherein the metal (b2) comprises one or more metals selected from the group consisting of sodium, potassium, and cesium, and one or more metals selected from the group consisting of nickel, lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, and bismuth.11. An epoxy resin composition according to any one of 8 to 10, wherein the amount of curing agent (C) is such that the equivalent amount of active hydrogen of the amino groups in the cured product (C) is in the range of 0.1 to 1.5 per mole of epoxy groups in the epoxy resin (A). 12. An epoxy resin composition according to any one of 1 to 11, wherein the curing agent (B) satisfies the relationship 1.5(X・n) ≤ Y・m (where X is the valence of the metal (b2), n is the amount of substance of the metal (b2), Y is the valence of the compound (b1), and m is the amount of substance of the compound (b1)). 13. An epoxy resin composition according to any one of 1 to 12, which does not contain imidazoles. 14. A cured product of the epoxy resin composition according to any one of 1 to 13.

[0010] According to the present invention, it is possible to provide an epoxy resin composition that achieves a high degree of both storage stability and reactivity, and a cured product thereof.

[0011] The present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be modified and implemented as appropriate without departing from the spirit of the invention. Furthermore, the "~" indicating a numerical range is used to mean that the numbers written before and after it are included as the lower limit and upper limit.

[0012] ≪Epoxy Resin Composition≫ The epoxy resin composition of this embodiment comprises an epoxy resin (A) and a curing agent (B), wherein the curing agent (B) contains a compound (b1) having one or more heteroatoms selected from the group consisting of nitrogen, oxygen, and phosphorus in its molecule, and a metal (b2) as raw materials, and the compound (b1) includes carboxylic acids, and the content of the curing agent (B) is 0.1 to 15 parts by mass per 100 parts by mass of the epoxy resin (A). The components constituting the epoxy resin composition of this embodiment will be described below.

[0013] <Epoxy Resin (A)> The epoxy resin (A) constituting the epoxy resin composition of this embodiment is not particularly limited, and a wide variety of compounds can be used. Furthermore, one type of epoxy resin may be used alone, or two or more types may be used in combination.

[0014] Specific examples of the epoxy resin (A) include, for example, aliphatic epoxy resins, hydroxybenzene type epoxy resins, hydroxynaphthalene type epoxy resins, biphenol type epoxy resins, bisphenol type epoxy resins, novolac type epoxy resins, triphenolmethane type epoxy resins, tetraphenolethane type epoxy resins, phenol or naphthol aralkyl type epoxy resins, phenylene or naphthylene ether type epoxy resins, dicyclopentadiene-phenol addition reaction type epoxy resins, phenolic hydroxyl group-alkoxy group-containing aromatic compound cocondensation type epoxy resins, glycidylamine type epoxy resins, and other naphthalene skeleton-containing epoxy resins.

[0015] Examples of the aliphatic epoxy resin include glycidyl ethers of various aliphatic polyol compounds. Examples of the aliphatic polyol compounds include ethylene glycol, propylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, heptamethylene glycol, 1,3-propanediol, 2-methylpropanediol, 1,2,2-trimethyl-1,3-propanediol, 2,2-dimethyl-3-isopropyl-1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,4-bis(hydroxymethyl)cyclohesane, and 2,2,4-tri Examples include aliphatic diol compounds such as methyl-1,3-pentanediol, 1,9-nonanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,15-pentadecanediol, 1,16-hexadecanediol, 2-methyl-1,11-undecanediol, 3-methyl-1,11-undecanediol, and 2,6,10-trimethyl-1,11-undecanediol; and trifunctional or more aliphatic polyol compounds such as trimethylolethane, trimethylolpropane, glycerin, hexanetriol, pentaerythritol, ditrimethylolpropane, and dipentaerythritol. Among these, glycidyl ether derivatives of aliphatic diol compounds are preferred because they exhibit excellent mechanical strength when the epoxy resin composition of this embodiment is cured.

[0016] The hydroxybenzene-type epoxy resins mentioned above include, for example, hydroxybenzenes such as phenol and cresol; dihydroxybenzenes such as hydroquinone, resorcinol, and catechol; trihydroxybenzenes such as pyrogallol, 1,2,4-trihydroxybenzene, and 1,3,5-trihydroxybenzene; triphenylmethane-type phenols such as 4,4',4"-trihydroxytriphenylmethane; alicyclic structure-containing phenols such as polyadditives of phenol and dicyclopentadiene, and polyadditives of phenol and terpene compounds; and so-called Zylok-type phenol resins which are condensation reaction products of phenol and phenylene dimethyl chloride or biphenylene dimethyl chloride, which are obtained by glycidyl etherification with an epihalohydrin. Furthermore, the compounds may have a structure in which a methyl group, a t-butyl group, or a halogen atom is substituted as a substituent on the aromatic ring of each of the above compounds.In addition, the alicyclic structure-containing phenols and the Zylok-type phenol resins may contain not only difunctional components but also trifunctional or higher components simultaneously.In the present invention, they may be used as is, or only the difunctional components may be isolated and used after purification through a column or other purification process.

[0017] Examples of the hydroxynaphthalene-type epoxy resin include naphthols such as bis(2-hydroxy-1-naphthyl)methane and bis(2-hydroxy-1-naphthyl)propane; tetrafunctional naphthols such as 1,1'-methylenebis-(2,7-naphthalenediol), 1,1'-binaphthalene-2,2',7,7'-tetraol, and 1,1'-oxybis-(2,7-naphthalenediol) obtained by coupling naphthols and dihydroxynaphthalenes; and dihydroxynaphthalenes such as 1,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, and 2,6-dihydroxynaphthalene, which are glycidyl etherified with an epihalohydrin. Furthermore, the compounds may have a structure in which a methyl group, a t-butyl group, or a halogen atom is substituted as a substituent on the aromatic ring of each of the above compounds.

[0018] The biphenol-type epoxy resin mentioned above can be obtained by glycidyl etherifying one or more biphenol compounds selected from the group consisting of biphenols such as biphenol and tetramethylbiphenol with an epihalohydrin. Among these, biphenol-type epoxy resins having an epoxy equivalent in the range of 150 to 300 g / equivalent are preferred.

[0019] The bisphenol-type epoxy resin mentioned above can be obtained by glycidyl etherifying one or more bisphenol compounds selected from the group consisting of bisphenol A, bisphenol F, bisphenol S, bisphenol AD, etc., with epihalohydrin. Among these, a bisphenol-type epoxy resin having an epoxy equivalent in the range of 150 to 300 g / equivalent is preferred.

[0020] The aforementioned novolac-type epoxy resin can be obtained by glycidyl etherifying a novolac resin, which consists of one or more phenolic compounds selected from the group consisting of various phenolic compounds such as phenol, cresol, xylenol, dihydroxybenzene, trihydroxybenzene, naphthol, dihydroxynaphthalene, bisphenol, and biphenol, with an epihalohydrin.

[0021] Examples of the aforementioned triphenolmethane-type epoxy resin include those having a repeating structural unit represented by the following structural formula (3).

[0022]

[0023] In the above formula (3), R ７ , R ８ Each of these is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkylene group having 1 to 10 carbon atoms, or a halogen atom. n is an integer of 1 or more. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0024] Examples of the phenol or naphthol aralkyl type epoxy resin include those having a molecular structure in which benzene or naphthalene to which a glycidyl ether group is bonded is knotted at a structural site represented by any of the following structural formulas (4-1) to (4-3).

[0025]

[0026] In the above formula (4-3), X is one of the following: an alkyl group having 1 to 6 carbon atoms, an alkylene group having 1 to 6 carbon atoms, an ether bond, a carbonyl group, a sulfide group, or a sulfonyl group.

[0027] Examples of the glycidylamine-type epoxy resin include N,N-diglycidylaniline, 4,4'-methylenebis[N,N-diglycidylaniline], triglycidylaminophenol, and N,N,N',N'-tetraglycidylxylylenediamine.

[0028] An example of the naphthalene skeleton-containing epoxy resin is an epoxy resin represented by any of the following structural formulas (5-1) to (5-3).

[0029]

[0030] Among the epoxy resins (A) mentioned above, from the viewpoint of improving the heat resistance and mechanical strength of the cured product obtained by curing the epoxy resin composition of this embodiment, it is preferable to use a hydroxybenzene epoxy resin, a hydroxynaphthalene type epoxy resin, a bisphenol type epoxy resin, a triphenolmethane type epoxy resin, a glycidylamine type epoxy resin, or an epoxy resin represented by any of the structural formulas (5-1) to (5-3) mentioned above.

[0031] In this embodiment, the properties of the epoxy resin (A) are not particularly limited. Specifically, an epoxy resin that is solid at 25°C may be used, a liquid epoxy resin having a viscosity of 5000 Pa·s or less at 25°C may be used, a liquid epoxy resin having a viscosity of 500 Pa·s or less may be used, or a liquid epoxy resin having a viscosity of 50 Pa·s or less may be used. When a liquid epoxy resin having a viscosity of 5000 Pa·s or less at 25°C is used as the epoxy resin (A), for example, the epoxy resin composition of this embodiment can be suitably used for the production of composite materials.

[0032] The epoxy equivalent of the epoxy resin (A) is preferably 100 to 500 g / equivalent, more preferably 110 to 400 g / equivalent, and even more preferably 120 to 300 g / equivalent. When the epoxy equivalent of the epoxy resin (A) is within the above range, the heat resistance of the resulting cured product can be improved. When two or more epoxy resins are used in combination, the epoxy equivalent of the epoxy resin (A) is the average epoxy equivalent of all the epoxy resins. The measurement of the epoxy equivalent can be carried out based on JIS K 7236.

[0033] In the epoxy resin composition of this embodiment, the content of the epoxy resin (A) is preferably 10 to 95% by mass, more preferably 20 to 90% by mass, even more preferably 30 to 80% by mass, and particularly preferably 40 to 80% by mass with respect to the entire epoxy resin composition.

[0034] In this embodiment, the epoxy resin (A) may be synthesized by a known method or a commercially available product may be used.

[0035] <Curing Agent (B)> The curing agent (B) constituting the epoxy resin composition of this embodiment is characterized by containing, as raw materials, a compound (b1) having one or more heteroatoms selected from the group consisting of nitrogen, oxygen, and phosphorus in the molecule and a metal (b2).

[0036] The curing agent (B) is, for example, a liquid curing agent having a viscosity of 20,000 mPa·s or less at 40°C. Having the viscosity of the curing agent (B) at 40°C within this range enhances ease of handling, uniformity of the curing reaction, and reactivity in minute spaces. The viscosity of the curing agent (B) at 40°C is preferably 15,000 mPa·s or less, more preferably 12,000 mPa·s or less, and even more preferably 10,000 mPa·s or less. The lower limit of the viscosity of the curing agent (B) at 40°C is not particularly limited, but is, for example, 10 mPa·s. The viscosity of the curing agent (B) can be measured by a rotational viscometer or the like.

[0037] The curing agent (B) comprises a compound (b1) having one or more heteroatoms selected from the group consisting of nitrogen, oxygen, and phosphorus in its molecule, and a metal (b2) as raw materials. The curing agent (B) may also contain, for example, a metal complex in which the compound (b1) and the metal (b2) are complexed by coordinate bonds. Furthermore, the curing agent (B) may contain a mixture of the compound (b1) and the metal (b2). Moreover, the metal complex and the mixture may be in a mixture.

[0038] As a result of intensive studies, the inventors of the present invention have found that by appropriately selecting the structure and type of the compound (b1) and the type of the metal (b2), and adjusting the interaction between the compound (b1) and the metal (b2) (for example, a coordination bond through an unshared electron pair of a heteroatom), it is possible to control the properties of the obtained curing agent and the reactivity of the epoxy derived from the curing agent. More specifically, by controlling the interaction between the compound (b1) and the metal (b2) to dissociate by, for example, thermal energy, an interaction (for example, a coordination bond through an unshared electron pair of a heteroatom) is generated between the compound (b1) and the metal (b2) in the low temperature range, the curing acceleration ability of the curing agent (B) is suppressed, and the progress of the curing reaction can be suppressed or prevented. Further, in the high temperature range, by controlling the dissociation of the interaction (coordination bond), the dissociated ligand attacks the epoxy ring, and the anionic polymerization of epoxy proceeds. Furthermore, it is considered that the central metal attacks the epoxy ring due to the dissociation of the ligand, and the cationic polymerization of epoxy also proceeds. Therefore, the curing reaction of the epoxy resin composition containing the curing agent can be rapidly advanced by using thermal energy (temperature) exceeding the interaction between the compound (b1) and the metal (b2) as a trigger, and as a result, it is possible to achieve both storage stability in the low temperature range and curability (reactivity) in the high temperature range.

[0039] Further, since the curing agent (B) also contributes to improving the adhesion to the substrate, when the epoxy resin composition of the present embodiment is used as a paint, an adhesive, a sealing material, a composite material, etc., its adhesion (adhesiveness) can be improved.

[0040] (Compound (b1) having at least one heteroatom selected from the group consisting of nitrogen, oxygen and phosphorus in the molecule) In the present embodiment, the compound (b1) which is a raw material of the curing agent (B) has at least one heteroatom having an unshared electron pair selected from the group consisting of nitrogen, oxygen and phosphorus in the molecule. The compound (b1) excludes those corresponding to the metal (b2) described later, that is, those containing a metal atom.

[0041] In this embodiment, compound (b1) includes carboxylic acids. By including carboxylic acids as compound (b1), the viscosity of the resulting curing agent (B) can be reduced, and the handling properties of the resulting epoxy resin composition can be improved.

[0042] The carboxylic acids mentioned above are not particularly limited as long as they are compounds having a carboxyl group, but specifically, examples include aliphatic carboxylic acids, alicyclic carboxylic acids, and aromatic carboxylic acids. The carboxylic acid may be either a saturated carboxylic acid or an unsaturated carboxylic acid.

[0043] The aliphatic carboxylic acid may be a primary, secondary, or tertiary carboxylic acid. The aliphatic group portion of the aliphatic carboxylic acid may be linear or branched. Examples of linear primary carboxylic acids include acetic acid, propionic acid, butyric acid (butanoic acid), valeric acid (pentanoic acid), caproic acid (hexanoic acid), enanthic acid (heptanoic acid), caprylic acid (octanoic acid), pelargonic acid (nonanoic acid), capric acid (decanoic acid), undecanoic acid (undecylic acid), lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanediic acid, dodecanediic acid, hexadecanedioic acid, octadecanediic acid, eicosanedioic acid, docosanedioic acid, and diglycolic acid. Branched primary carboxylic acids include structural isomers of the linear primary carboxylic acids mentioned above. Examples of the branched primary carboxylic acids include, specifically, 3,5,5-trimethylhexanoic acid, 3-methylvaleric acid, 4-methylvaleric acid, 5-methylhexanoic acid, 4-methyloctanoic acid, 4-ethyloctanoic acid, 4-methylnonanoic acid, 1,2,4-butanetricarboxylic acid, 1,3,5-pentanetricarboxylic acid, 1,2,6-hexanetricarboxylic acid, 1,3,6-hexanetricarboxylic acid, 1,3,5-cyclohexanetricarboxylic acid, trimesic acid, and the like. The secondary carboxylic acids include structural isomers of the linear primary carboxylic acids. Examples of the secondary carboxylic acids include isobutyric acid, 2-methylbutyric acid, 2-ethylbutyric acid, 2-methylvaleric acid, 2-methylhexanoic acid, octic acid (2-ethylhexanoic acid), 2-methylheptanoic acid, 2-propylbutyric acid, 2-hexylvaleric acid, 2-hexyldecanoic acid, 2-heptylundecanoic acid, 2-methylhexadecanoic acid, 4-methylcyclohexanecarboxylic acid, hexadecendioic acid, octadecendioic acid, eicosendioic acid, and 2,2,4-trimethyladipic acid. The tertiary carboxylic acids include structural isomers of the linear primary carboxylic acids.Examples of the aforementioned tertiary carboxylic acids include pivalic acid, 2,2-dimethylbutyric acid, 2,2-dimethylhexanoic acid, 2,2-dimethylheptanoic acid, and neodecanoic acid.

[0044] Examples of the alicyclic carboxylic acid include, specifically, cyclohexanecarboxylic acid, methylcyclohexanecarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, cyclohexenedicarboxylic acid, norbornanedicarboxylic acid, tris(2-carboxyethyl) isocyanurate, DL-pipecolic acid, and the like.

[0045] Examples of the aforementioned aromatic carboxylic acids include salicylic acid, phthalic acid, benzoic acid, toluic acid, ethylbenzoic acid, picolinic acid, methyl picolinic acid, dipicolinic acid, phenylacetic acid, terephthalic acid, isophthalic acid, phthalic acid, m-xylylenedicarboxylic acid, p-xylylenedicarboxylic acid, 3-hydroxypicolinic acid, pyridine-3-carboxylic acid, pyridine-4-carboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid.

[0046] Furthermore, the unsaturated carboxylic acid is not particularly limited as long as it is a carboxylic acid containing an unsaturated group in its structure, and examples include (meth)acrylic acid, 2-methchloroyloxyethyl succinic acid, fumaric acid, maleic acid, crotonic acid, geranic acid, cinnamic acid, eicosendiic acid, and the like.

[0047] Among these, from the viewpoint of achieving a high degree of both storage stability and curability (reactivity), the number of carbon atoms in the carboxylic acids is preferably 2 to 30, more preferably 4 to 20, and even more preferably 6 to 12.

[0048] Furthermore, from the viewpoint of adjusting the viscosity of the resulting curing agent (B), the carboxylic acids are preferably aliphatic carboxylic acids. Among the aliphatic carboxylic acids, it is more preferable that they be secondary carboxylic acids, tertiary carboxylic acids, or unsaturated carboxylic acids, and even more preferable that they be secondary carboxylic acids or tertiary carboxylic acids.

[0049] Furthermore, in this embodiment, the carboxylic acids may be used individually or in combination of two or more. For example, the primary aliphatic carboxylic acid may be used in combination with the secondary aliphatic carboxylic acid and / or the tertiary aliphatic carboxylic acid.

[0050] In the case where the epoxy resin composition of this embodiment consists of the epoxy resin (A), the curing agent (B), the <other resins> described later, and the <other components> described later, the amount of carboxylic acids used is preferably such that the carboxyl groups of the carboxylic acids are in the range of 0.8 to 20 moles, more preferably in the range of 0.9 to 15 moles, even more preferably in the range of 1.0 to 10 moles, and particularly preferably in the range of 1.0 to 6 moles, per mole of metal atoms in the metal (b2). If the amount of carboxylic acids used is within the above range, an epoxy resin composition that achieves a high degree of both storage stability and curability (reactivity) can be obtained. When multiple types of carboxylic acids are used as the carboxylic acids, it is preferable to set the total number of carboxyl groups that each carboxylic acid has to be within the above range. Furthermore, if the epoxy resin composition of this embodiment also contains a curing agent (C) described later, the amount of carboxylic acids used is preferably such that the amount of carboxyl groups of the carboxylic acids is in the range of 0.8 to 20 moles, more preferably in the range of 0.9 to 15 moles, even more preferably in the range of 1.0 to 10 moles, and particularly preferably in the range of 1.0 to 8 moles, per mole of metal atoms in the metal (b2) described later. By using an amount of carboxylic acids within the above range, an epoxy resin composition that achieves a high degree of both storage stability and curability (reactivity) can be obtained.

[0051] In this embodiment, compound (b1) essentially contains carboxylic acids, but may also contain other compounds having specific heteroatoms in the molecule. That is, compound (b1) may be alone or two or more may be used in combination. Specific examples of compounds (b1) other than carboxylic acids that have specific heteroatoms in the molecule include amines, imidazoles, quaternary ammonium salts, phosphine compounds, phosphonium salts, triazine ring-containing compounds, alcohols, and the like.

[0052] Examples of the amines include N-methylmorpholine, pyridine, picolinamide, picolylamine, phenanthroline, 1,8-diazabicyclo[5.4.0]undecene-7 (DBU), 1,5-diazabicyclo[4.3.0]nonene-5 (DBN), 1,4-diazabicyclo[2.2.2]octane (DABCO), 4-dimethylaminoamine (DMAP), dicyandiamide (DICY), tri-n-butylamine, dimethylbenzylamine, butylamine, 1,2-propanediamine, 1,2-cyclohexanediamine, octylamine. N, monoethanolamine, diethanolamine, triethanolamine, triethylamine, trimethylenediamine, ethylenediamine, N,N,N',N'-tetramethylethylenediamine, pentamethyldiethylenetriamine, triethylenediamine, dipropylenediamine, N,N,N',N'-tetramethylpropylenediamine, tetramethylenediamine, pentanediamine, hexamethylenediamine, trimethylhexamethylenediamine, N,N,N',N'-tetramethylhexamethylenediamine, N,N-dimethylcyclohexyl Amines, diethylenetriamine (DTA), triethylenetetramine, tetraethylenepentamine, dimethylaminopropylamine, diethylaminopropylamine, dibutylaminopropylamine, 1,4-diazabicyclo(2,2,2)octane(triethylenediamine), polyoxyethylenediamine, polyoxypropylenediamine, bis(2-dimethylaminoethyl) ether, dimethylaminoethoxyethoxyethanol, dimethylaminohexanol, benzylmethylamine, m-xylenediamine, α-methylbenzylmethylamine , 2-[[(2-dimethylamino)ethyl]methylamino]ethanol, 2,2'-[propane-1,2-diyrbis(azanylylidenemetanylylidene)]diphenol, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, methylmorpholine)aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropylmethyldimethoxysilane, tetramethylammonium hydroxide, 8-quinolinol, 5-chloro-8-quinolinol, 2,Examples include 2'-bipyridyl and its derivatives, 2,2'-[propane-1,2-diylbis(azanylylidenemetanylylidene)]diphenol and its derivatives, and 2,2'-methylenebis[6-(2h-benzotriazole-2-yl)-4-tert-octylphenol]. When the amines are used as compound (b1), their content is preferably 0.1 to 10 moles, more preferably 0.2 to 5 moles, even more preferably 0.3 to 3 moles, and particularly preferably 0.4 to 2 moles, per mole of metal atoms in the metal (b2). When the content of the amines is within the above range, an epoxy resin composition that achieves a high degree of both storage stability and curability (reactivity) can be obtained.

[0053] Examples of the imidazoles include imidazole, 1-methylimidazole, 2-methylimidazole, 3-methylimidazole, 4-methylimidazole, 1-ethylimidazole, 2-ethylimidazole, 3-ethylimidazole, 4-ethylimidazole, 1-n-propylimidazole, 2-n-propylimidazole, 1-isopropylimidazole, 2-isopropylimidazole, 1-n-butylimidazole, 2-n-butylimidazole, 1-isobutylimidazole, 2-isobutylimidazole, 2-undecyl-1H-imidazole, 2-heptadecyl-1H-imidazole, 1-vinylimidazole, 1,2-dimethylimidazole, 1,3-dimethylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 1- Examples include phenylimidazole, 2-phenyl-1H-imidazole, 4-methyl-2-phenyl-1H-imidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 2-phenylimidazole isocyanuric acid adduct, 2-methylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and 1-cyanoethyl-2-phenyl-4,5-di(2-cyanoethoxy)methylimidazole. Furthermore, the imidazoles may also be imidazolium salts such as 1-dodecyl-2-methyl-3-benzylimidazolium chloride and 1-benzyl-2-phenylimidazole hydrochloride. Among these, in this embodiment, it is preferable to use imidazoles having a substituent at position 1. Examples of substituents include methyl groups, ethyl groups, isopropyl groups, or vinyl groups.Imidazoles having a substituent at position 1 include at least one of the following: 1-methylimidazole, 1-ethylimidazole, 1-n-butylimidazole, 1-isobutylimidazole, 1-isopropylimidazole, 1-phenylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-benzyl-2-phenylimidazole hydrochloride, and 1-vinylimidazole. It is preferable to use at least one of 1-methylimidazole, 1-ethylimidazole, 1-isopropylimidazole, 1-phenylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1-vinylimidazole, and it is particularly preferable to use at least one of 1-methylimidazole and 1-vinylimidazole. When the above imidazoles are used as the compound (b1), the content is preferably 0.1 to 10 moles, more preferably 0.2 to 5 moles, even more preferably 0.3 to 3 moles, and particularly preferably 0.4 to 2 moles per mole of metal atoms in the metal (b2). When the content of the imidazoles is within the aforementioned range, an epoxy resin composition that achieves a high degree of both storage stability and curability (reactivity) can be obtained.

[0054] Examples of the quaternary ammonium salt include tetraalkylammonium salt, trioctylmethylammonium chloride, and trioctylmethylammonium acetate. When the quaternary ammonium salt is used as compound (b1), its content is preferably 0.1 to 10 moles, more preferably 0.2 to 5 moles, even more preferably 0.3 to 3 moles, and particularly preferably 0.4 to 2 moles, per mole of metal atoms in the metal (b2). When the content of the quaternary ammonium salt is within the above range, an epoxy resin composition that achieves a high degree of both storage stability and curability (reactivity) can be obtained.

[0055] Examples of the phosphine compounds include trimethylphosphine, tributylphosphine, trioctylphosphine, tri-tert-butylphosphine, triphenylphosphine, tritlylphosphine, trixylylphosphine, tri-tert-butoxyphenylphosphine, diphenylpyridylphosphine, diphenylcyclohexylphosphine, tricyclohexylphosphine, di-tert-butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, di-tert-butylphenylphosphine, and [4-(N,N-dimethylamino)phenyl]di-tert-butylphosphine. Examples include tris(diethylamino)phosphine, bis(diphenylphosphino)ethane, bis(diphenylphosphino)propane, bis(diphenylphosphino)butane, bis(diphenylphosphino)pentane, bis(diphenylphosphino)diphenyl ether, 9,9-dimethyl-4,5-bis(diphenylphosphino)-9H-xanthene, 9,9-dimethyl-4,5-bis(di-tert-butylphosphino)-9H-xanthene, bis(diphenylphosphino)ferrocene, bis(di-iso-propylphosphino)ferrocene, bis(di-tert-butylphosphino)ferrocene, and diphenylphosphinostyrene. When the phosphine compound is used as compound (b1), its content is preferably 0.1 to 10 moles, more preferably 0.2 to 5 moles, even more preferably 0.3 to 3 moles, and particularly preferably 0.4 to 2 moles, per mole of metal atoms in the metal (b2). When the content of the phosphine compound is within the above range, an epoxy resin composition that achieves a high degree of both storage stability and curability (reactivity) can be obtained.

[0056] Examples of the phosphonium salts include tetramethylphosphonium chloride, tetraethylphosphonium chloride, tetrapropylphosphonium chloride, tetrabutylphosphonium chloride, tetrabutylphosphonium bromide, trimethyl(2-hydroxypropyl)phosphonium chloride, triphenylphosphonium chloride, benzylphosphonium chloride, and methyltributylphosphonium dimethyl phosphate. When the phosphonium salt is used as compound (b1), its content is preferably 0.1 to 10 moles, more preferably 0.2 to 5 moles, even more preferably 0.3 to 3 moles, and particularly preferably 0.4 to 2 moles, per mole of metal atoms in the metal (b2). When the content of the phosphonium salt is within the above range, an epoxy resin composition that achieves a high degree of both storage stability and curability (reactivity) can be obtained.

[0057] In addition to the above, other examples include sulfur compounds such as thiolactic acid, 2-aminothiophenol, and 2,2'-dithiodianiline. Tert-butyl isocyanide and adamantyl isocyanide can also be used.

[0058] Furthermore, in this embodiment, the compound (b1) having one or more heteroatoms selected from the group consisting of nitrogen, oxygen, and phosphorus in its molecule may also contain an organic solvent. Examples of the aforementioned organic solvents include ketone solvents such as methyl ethyl ketone, acetone, dimethylformamide, methyl isobutyl ketone, cyclohexanone, and dimethylacetamide; cyclic ether solvents such as tetrahydrofuran and dioxolane; ester solvents such as methyl acetate, ethyl acetate, and butyl acetate; alcohol solvents such as carbitol, cellosolve, methanol, ethanol, propanol, isopropanol, butanol, cyclohexanol, and propylene glycol monomethyl ether; ether solvents such as propyl ether, methyl cellosolve, cellosolve, butyl cellosolve, and methyl carbitol; glycol ether solvents such as alkylene glycol monoalkyl ether, dialkylene glycol monoalkyl ether, and dialkylene glycol monoalkyl ether acetate; vegetable oils such as soybean oil, linseed oil, rapeseed oil, and safflower oil; and methoxypropanol, cyclohexanone, methyl cellosolve, diethylene glycol monoethyl ether acetate, and propylene glycol monomethyl ether acetate. These organic solvents can be used individually or in combination of two or more. By including the organic solvent as compound (b1), the metal carboxylate salt obtained from the carboxylic acids and the metal (b2) as raw materials dissolves in the organic solvent. This allows for easy adjustment of the viscosity of the resulting curing agent (B), and an epoxy resin composition with excellent handling and dispersibility is obtained. In this embodiment, the organic solvent is used as a general organic solvent as described above, but a portion of the organic solvent may coordinate to a metal cation derived from the metal (b2) described later.

[0059] Furthermore, the number of heteroatoms in compound (b1) is preferably two or more, and more preferably two to five. When the number of heteroatoms in compound (b1) is within the above range, the interaction between the heteroatoms in compound (b1) and the metal (b2) facilitates the formation of a more stable complex, thereby improving storage stability.

[0060] The molecular weight of compound (b1) is preferably 500 or less. When the molecular weight of compound (b1) is within the above range, the complex formed by the interaction of heteroatoms in compound (b1) with the metal in metal (b2) is easily stabilized, and storage stability is improved. The molecular weight of compound (b1) is more preferably 60 to 500, even more preferably 70 to 400, and particularly preferably 80 to 300.

[0061] Furthermore, in this embodiment, the amount of compound (b1) used is preferably 0.8 to 10 moles per mole of metal atoms in the metal (b2) described later. By using compound (b1) within this range, an epoxy resin composition that achieves a high degree of both storage stability and curability (reactivity) can be obtained. The amount of compound (b1) used is more preferably 0.9 to 8 moles, and particularly preferably 1.0 to 5 moles.

[0062] When the valency of metal (b2) is X and the amount of substance is n, and the valency of compound (b1) is Y and the amount of substance is m, the curing agent (B) preferably satisfies the relationship 1.5(X・n) ≤ Y・m, more preferably 2.0(X・n) ≤ Y・m, and even more preferably 3.0(X・n) ≤ Y・m. It is presumed that the latent properties of the curing agent (B) can be increased by excessively coordinating compound (b1) to metal (b2). For example, when there are two or more types of metal (b2), the valency X is the average amount of substance of metal (b2). Similarly, when there are two or more types of compound (b1), the valency Y is the average amount of substance of compound (b1).

[0063] (Metal (b2)) In this embodiment, the metal (b2) is a substance containing at least one metal element. The substance containing the metal element may be, for example, a pure metal or a metal compound. Specific examples of the metal compound include metal hydroxides, metal oxides, metal salts, and the like.

[0064] Examples of the aforementioned metal salts include nitrates, carbonates, halide salts, sulfates, chlorides, and fatty acid metal salts. These metal salts can be used individually or in combination of two or more.

[0065] The metal (b2) is not particularly limited as long as it is a metal from groups 1 to 16 of the periodic table, excluding hydrogen, boron, carbon, nitrogen, oxygen, silicon, phosphorus, sulfur, germanium, arsenic, selenium, antimony, tellurium, bismuth, and polonium, and a metalloid (boron, carbon, silicon, phosphorus, germanium, arsenic, selenium, antimony, tellurium, bismuth, polonium). Examples of metals that make up the aforementioned metal (b2) include lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, aluminum, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, iridium, platinum, gold, bismuth, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, and the like. Among these, it is preferable that the metal constituting the metal (b2) includes one or more metals selected from the group consisting of sodium, potassium, magnesium, calcium, strontium, barium, cesium, aluminum, vanadium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, gadolinium, and bismuth; more preferably that it includes one or more metals selected from the group consisting of potassium, cesium, cobalt, nickel, copper, zinc, neodymium, and bismuth; and even more preferably that it includes one or more metals selected from the group consisting of potassium, nickel, zinc, neodymium, and bismuth. When the metal constituting the metal (b2) is one of the above, the heteroatoms in compound (b1) readily form a complex (e.g., coordination state) that interacts with the metal (b2), and the resulting epoxy resin composition can achieve a high degree of both storage stability and reactivity.

[0066] The form of the curing agent (B) in the epoxy resin composition according to this embodiment is not particularly limited. The curing agent (B) may be solid (including waxy) or liquid (including paste) at room temperature (25°C).

[0067] The content of the curing agent (B) in the epoxy resin composition according to this embodiment is 0.1 to 15 parts by mass, more preferably 1 to 12 parts by mass, and particularly preferably 2 to 10 parts by mass, per 100 parts by mass of the epoxy resin (A). When the content of the curing agent (B) is within the above range, a high degree of both storage stability and reactivity can be achieved. In the case where the epoxy resin composition according to this embodiment contains a curing agent (C) described later, the content of the curing agent (B) is preferably 0.1 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, and particularly preferably 1 to 8 parts by mass, per 100 parts by mass of the epoxy resin (A), from the viewpoint of further improving storage stability and reactivity.

[0068] In the epoxy resin composition according to this embodiment, the solid content of the curing agent (B) is preferably 0.1 to 15 parts by mass, more preferably 1 to 10 parts by mass, and particularly preferably 2 to 8 parts by mass, based on 100 parts by mass of the solid content of the epoxy resin (A), from the viewpoint of achieving both storage stability and reactivity. When the epoxy resin composition according to this embodiment contains a curing agent (C) described later, the solid content of the curing agent (B) is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 8 parts by mass, and particularly preferably 1 to 5 parts by mass, based on 100 parts by mass of the solid content of the epoxy resin (A). When the curing agent (C) is included, if the solid content of the curing agent (B) is within the above range, a high degree of both storage stability and reactivity can be achieved.

[0069] Furthermore, the metal content in the curing agent (B) is preferably 1 to 30% by mass. By having the metal content in the curing agent (B) within this range, a high degree of both storage stability and reactivity can be achieved. The metal content in the curing agent (B) is more preferably 3 to 28% by mass, and particularly preferably 4 to 26% by mass.

[0070] The curing agent (B) is obtained using the compound (b1) and the metal (b2) as raw materials. Specifically, when using only the carboxylic acids as the compound (b1), the curing agent (B) can be produced by adding a metal hydrate, hydroxide, carbonate, or oxide to the carboxylic acids and then stirring and reacting under heating conditions. The reaction temperature is usually 10°C to 200°C, preferably 20°C to 150°C. The reaction time is usually 0.1 to 10 hours, preferably 0.5 to 5 hours. When using a primary aliphatic carboxylic acid and a secondary aliphatic carboxylic acid and / or a tertiary aliphatic carboxylic acid in combination as the carboxylic acids, it is preferable to first mix the secondary aliphatic carboxylic acid and / or the tertiary aliphatic carboxylic acid with a metal hydrate or the like to form a metal salt of the secondary aliphatic carboxylic acid and / or a metal salt of the tertiary aliphatic carboxylic acid, and then add the primary aliphatic carboxylic acid. Another method for producing the curing agent (B) is to dissolve the carboxylic acids as salts soluble in water or alcohol solvents, such as sodium salts or potassium salts, in water or alcohol solvents, add a metal salt soluble in water or alcohol solvents to this mixture, carry out an ion exchange reaction called double decomposition, wash with water, dehydrate (desolvent remover), and filter. The reaction temperature and reaction time in the ion exchange reaction are preferably within the same range as described above. In this embodiment, the curing agent (B) obtained above may be used as is, or it may be used after undergoing a purification process such as column chromatography.

[0071] Furthermore, in this embodiment, if the curing agent (B) is a liquid curing agent, an organic solvent other than compound (b1) may be included in order to adjust the viscosity of the liquid curing agent and obtain an epoxy resin composition with excellent handling and dispersibility. Examples of organic solvents other than compound (b1) include hydrocarbon solvents such as toluene, xylene, heptane, hexane, and mineral spirits; aromatic solvents such as toluene, xylene, and solvent naphtha; and alicyclic solvents such as cyclohexane and methylcyclohexane. These organic solvents can be used individually or in combination of two or more. In addition, commercially available organic solvents that do not fall under the above compound (b1) can also be used. Examples of such commercially available products include: ENEOS Corporation's "Spindle Oil No. 1", "Solvent No. 3", "Solvent No. 4", "Solvent No. 5", "Solvent No. 6", "Naphthezol H", "Alken 56NT", "AF Solvent No. 4", "AF Solvent No. 5", "AF Solvent No. 6", "AF Solvent No. 7"; Mitsubishi Chemical Corporation's "Diadol 13", "Dialen 168"; Nissan Chemical Corporation's "F Oxocol", "F Oxocol 180"; Idemitsu Kosan Co., Ltd.'s "Supersol LA35", "Supersol LA38"; ExxonMobil Examples include Chemical's "Exol D80," "Exol D110," "Exol D120," "Exol D130," "Exol D160," "Exol D100K," "Exol D120K," "Exol D130K," "Exol D280," "Exol D300," and "Exol D320."

[0072] <Curing agent (C)> The epoxy resin composition according to this embodiment may contain a curing agent (C) other than the curing agent (B) mentioned above, from the viewpoint of further enhancing reactivity.

[0073] The curing agent (C) is not particularly limited as long as it reacts with epoxy groups. Specifically, examples of the curing agent (C) include amine compounds, acid anhydrides, amide compounds, phenolic hydroxyl group-containing compounds, carboxylic acids, thiol compounds, azo compounds, organic peroxides, polyol compounds, cyanate ester resins, resins having a benzoxazine structure, and activated ester resins. The curing agent (C) can be used alone or in combination of two or more types.

[0074] Examples of the amine compounds include trimethylenediamine, ethylenediamine, N,N,N',N'-tetramethylethylenediamine, pentamethyldiethylenetriamine, triethylenediamine, dipropylenediamine, N,N,N',N'-tetramethylpropylenediamine, tetramethylenediamine, pentanediamine, hexamethylenediamine, trimethylhexamethylenediamine, N,N,N',N'-tetramethylhexamethylenediamine, N,N-dimethylcyclohexylamine, diethylenetriamine (DTA), and triethylenetetramine. Aliphatic amine compounds such as tetraethylenepentamine, dimethylaminopropylamine, diethylaminopropylamine, dibutylaminopropylamine, 1,4-diazabicyclo(2,2,2)octane(triethylenediamine), polyoxyethylenediamine, polyoxypropylenediamine, bis(2-dimethylaminoethyl) ether, dimethylaminoethoxyethoxyethanol, triethanolamine, dimethylaminohexanol, benzylmethylamine, dimethylbenzylamine, m-xylenediamine, α-methylbenzylmethylamine, etc.

[0075] Alicyclic and heterocyclic amine compounds such as piperidine, piperazine, menthanediamine, isophoronediamine, methylmorpholine, ethylmorpholine, N,N',N''-tris(dimethylaminopropyl)hexahydro-s-triazine, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxyspiro(5,5)undecane adduct, N-aminoethylpiperazine, trimethylaminoethylpiperazine, bis(4-aminocyclohexyl)methane, N,N'-dimethylpiperazine, and 1,8-diazabicyclo-[5.4.0]-undecene (DBU);

[0076] Aromatic amine compounds such as o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, pyridine, and picoline;

[0077] Modified polyamine compounds such as epoxy-modified polyamines (polyamines modified by epoxy compound addition reactions), Michael addition-modified polyamines (polyamines modified by Michael addition reactions), Mannich-modified polyamines (polyamines modified by Mannich addition reactions), thiourea-modified polyamines (polyamines modified by thiourea addition reactions), and ketone-modified polyamines (polyamines modified by ketone blockade reactions);

[0078] Examples include dicyandiamide, guanidine, organic acid hydrazides, diaminomaleonitrile, amineimides, boron trifluoride-piperidine complexes, boron trifluoride-monoethylamine complexes, and other amine compounds. These amine compounds can be used individually or in combination of two or more.

[0079] Examples of the aforementioned acid anhydrides include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, polypropylene glycol maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride. These acid anhydrides can be used individually or in combination of two or more.

[0080] Examples of the amide compounds include polyamidoamines. Polyamidoamines can be obtained by reacting, for example, aliphatic polyamines or polyamines having polyoxyalkylene chains. These amide compounds can be used individually or in combination of two or more.

[0081] The phenolic hydroxyl group-containing compound is not particularly limited, and examples include the hydroxybenzenes, dihydroxybenzenes, naphthols, and dihydroxynaphthalene. These phenolic hydroxyl group-containing compounds can be used individually or in combination of two or more.

[0082] Examples of the carboxylic acids include those listed in the section "Compounds having one or more heteroatoms selected from the group consisting of nitrogen, oxygen, and phosphorus in their molecule (b1)". Other examples include carboxylic acid-terminated polyesters, polyacrylic acid, maleic acid-modified polypropylene glycol, and carboxylic acid polymers such as copolymers of styrene and maleic anhydride. These carboxylic acids can be used individually or in combination of two or more.

[0083] The thiol compound is preferably one that contains two or more thiol groups in one molecule. Examples include 3,3'-dithiodipropionic acid, trimethylolpropane tris(thioglycolate), pentaerythritol tetrakis(thioglycolate), ethylene glycol dithioglycolate, 1,4-bis(3-mercaptobutyryloxy)butane, tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), dipentaerythritol hexakis(3-mercaptopropionate), 1,3,4,6-tetrakis(2-mercaptoethyl)glycoluryl, 4-butanedithiol, 1,6-hexanedithiol, and 1,10-decandithiol. These thiol compounds can be used individually or in combination of two or more.

[0084] Examples of the azo compound include azobisisobutyronitrile.

[0085] Examples of the aforementioned organic peroxides include ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxyesters, peroxydicarbonates, and alkyl peroxycarbonates. These organic peroxides can be used individually or in combination of two or more.

[0086] Examples of the polyol compounds include polyol monomers such as ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, glycerin, glycerin mono(meth)acrylate, trimethylolethane, trimethylolmethane mono(meth)acrylate, trimethylolpropane, trimethylolpropane mono(meth)acrylate, pentaerythritol mono(meth)acrylate, and pentaerythritol di(meth)acrylate; and the polyol monomers and succinic acid, adipic acid, azelaic acid, sebastic acid Examples include polyester polyols obtained by co-condensation with dicarboxylic acids such as nic acid, terephthalic acid, isophthalic acid, orthophthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, and 1,4-cyclohexanedicarboxylic acid; lactone-type polyester polyols obtained by polycondensation reaction of the polyol monomer with various lactones such as ε-caprolactone, δ-valerolactone, and 3-methyl-δ-valerolactone; and polyether polyols obtained by ring-opening polymerization of the polyol monomer with cyclic ether compounds such as ethylene oxide, propylene oxide, tetrahydrofuran, ethyl glycidyl ether, and propyl glycidyl ether. These polyol compounds can be used individually or in combination of two or more.

[0087] Examples of the cyanate ester resins include bisphenol A type cyanate ester resin, bisphenol F type cyanate ester resin, bisphenol E type cyanate ester resin, bisphenol S type cyanate ester resin, bisphenol sulfide type cyanate ester resin, phenylene ether type cyanate ester resin, naphthylene ether type cyanate ester resin, biphenyl type cyanate ester resin, tetramethylbiphenyl type cyanate ester resin, polyhydroxynaphthalene type cyanate ester resin, phenol novolac type cyanate ester resin, and cresol novolac. Examples include cyanate ester resins of the cubic type, triphenylmethane type, tetraphenylethane type, dicyclopentadiene-phenol addition reaction type, phenol aralkyl type, naphthol novolac type, naphthol aralkyl type, naphthol-phenol co-condensed novolac type, naphthol-cresol co-condensed novolac type, biphenyl-modified novolac type, and anthracene type. These cyanate ester resins can be used individually or in combination of two or more types.

[0088] Among the cyanate ester resins mentioned above, bisphenol A type cyanate ester resin, bisphenol F type cyanate ester resin, bisphenol E type cyanate ester resin, polyhydroxynaphthalene type cyanate ester resin, naphthylene ether type cyanate ester resin, and novolac type cyanate ester resin are preferred in terms of obtaining cured products with particularly excellent heat resistance, and dicyclopentadiene-phenol addition reaction type cyanate ester resin is preferred in terms of obtaining cured products with excellent dielectric properties.

[0089] There are no particular limitations on the resin having the benzoxazine structure, but examples include the reaction product of bisphenol F, formalin, and aniline (F-a type benzoxazine resin), the reaction product of diaminodiphenylmethane, formalin, and phenol (P-d type benzoxazine resin), the reaction product of bisphenol A, formalin, and aniline, the reaction product of dihydroxydiphenyl ether, formalin, and aniline, the reaction product of diaminodiphenyl ether, formalin, and phenol, the reaction product of dicyclopentadiene-phenol addition resin, formalin, and aniline, the reaction product of phenolphthalein, formalin, and aniline, and the reaction product of diphenyl sulfide, formalin, and aniline. These resins having the benzoxazine structure can be used individually or in combination of two or more types.

[0090] There are no particular restrictions on the activated ester resin, but generally, 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. The activated ester resin is preferably obtained by a condensation reaction between carboxylic acids and / or thiocarboxylic acids and hydroxy compounds and / or thiol compounds. Particularly from the viewpoint of improving heat resistance, activated ester resins obtained from carboxylic acids or their halides and hydroxy compounds are preferred, and activated ester resins obtained from carboxylic acids and / or their halides and phenol compounds and / or naphthol compounds are more preferred. Examples of phenol compounds or naphthol compounds include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, dihydroxydiphenyl ether, phenolphthalein, 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, phloroglucin, benzenetriol, and dicyclopentadiene-phenol addition resins.

[0091] Specifically, the active ester resins are preferably active ester resins containing a dicyclopentadiene-phenol addition structure, active ester resins containing a naphthalene structure, active ester resins which are acetylated phenol novolacs, and active ester resins which are benzoylated phenol novolacs. Among these, active ester resins containing a dicyclopentadiene-phenol addition structure and active ester resins containing a naphthalene structure are more preferred because they are excellent at improving peel strength. These active ester resins can be used individually or in combination of two or more types.

[0092] The content of the curing agent (C) is preferably in the range of 1 to 60 parts by mass, more preferably 5 to 50 parts by mass, and particularly preferably 6 to 40 parts by mass, per 100 parts by mass of solids of the epoxy resin (A), in order to obtain an epoxy resin composition that has excellent storage stability and reactivity and can form a cured product with excellent heat resistance and adhesion to the substrate. Also, from the same viewpoint as above, the content of the curing agent (C) is preferably such that the amount of functional groups in the curing agent (C) that can react with the epoxy groups is 0.3 to 5 equivalents, more preferably 0.5 to 3 equivalents, and even more preferably 0.7 to 2 equivalents, per mole of epoxy groups in the epoxy resin (A). Examples of functional groups in the curing agent (C) that can react with the epoxy groups include carboxyl groups, phenolic hydroxyl groups, and amino groups.

[0093] In this embodiment, since an epoxy resin composition is obtained that has excellent storage stability and reactivity, and furthermore, can form a cured product with excellent heat resistance and adhesion to the substrate, it is preferable to include an amine compound as the curing agent (C) other than the curing agent (B), and more preferably to include dicyandiamide. When dicyandiamide is included, the starting temperature of the curing reaction tends to be high, but in this embodiment, by adding the specific curing agent (B) mentioned above, the curing reaction can proceed sufficiently even at low temperatures.

[0094] Furthermore, when the curing agent (C) is dicyandiamide, the content of the curing agent (C) is preferably in the range of 1 to 50 parts by mass, more preferably in the range of 3 to 40 parts by mass, even more preferably in the range of 5 to 20 parts by mass, and particularly preferably in the range of 6 to 15 parts by mass, per 100 parts by mass of solids of the epoxy resin (A), in order to obtain an epoxy resin composition that has excellent storage stability and reactivity and that can form a cured product with excellent heat resistance and adhesion to the substrate. When the content of the curing agent (C) is within the above range, an epoxy resin composition that has excellent storage stability and reactivity and that can form a cured product with excellent heat resistance and adhesion to the substrate is obtained. Furthermore, from the same viewpoint as above, when the curing agent (C) is dicyandiamide, the content of dicyandiamide is preferably in an amount such that the equivalent amount of active hydrogen of the amino group of dicyandiamide is 0.1 to 1.5 per mole of epoxy group of epoxy resin (A), more preferably in an amount such that it is 0.2 to 1.2, and even more preferably in an amount such that it is 0.3 to 1.1.

[0095] The epoxy resin composition of this embodiment is not particularly limited in terms of the combination of components as long as it contains the epoxy resin (A) and the curing agent (B), but it is preferable that it is one of the following combinations. (1) an embodiment in which the compound (b1) is a carboxylic acid; (2) an embodiment in which the compound (b1) is a carboxylic acid and the metal (b) includes one metal selected from the group consisting of potassium, cobalt, nickel, copper, and zinc; (3) an embodiment in which the compound (b1) is a carboxylic acid and the metal (b2) includes one or more metals selected from the group consisting of sodium, potassium, magnesium, calcium, strontium, barium, manganese, cobalt, nickel, copper, lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, and bismuth, and further contains dicyandiamide as the curing agent (C); (4) an embodiment in which a primary aliphatic carboxylic acid and a secondary aliphatic carboxylic acid and / or the tertiary aliphatic carboxylic acid are used in combination as the compound (b1), the metal (b2) includes at least one selected from the group consisting of sodium, potassium, and cesium, and further contains dicyandiamide as the curing agent (C).

[0096] The above (1) is an embodiment in which only carboxylic acids are used as the compound (b1). In this embodiment, an anion (carboxylic acid anion) made of the carboxylic acids coordinates to the metal cation derived from the metal (b2) to form a metal carboxylate salt. Furthermore, in this embodiment, from the viewpoint of further improving handling and dispersibility, the carboxylic acids are preferably aliphatic carboxylic acids. Among the aliphatic carboxylic acids, the secondary carboxylic acids or tertiary carboxylic acids are more preferred.

[0097] The above (2) is an embodiment in which the compound (b1) is a carboxylic acid and the metal constituting the metal (b2) is at least one metal selected from the group consisting of potassium, cobalt, nickel, copper, and zinc.

[0098] The above-mentioned (3) is an embodiment in which the compound (b1) is a carboxylic acid, the metal (b2) contains one or more metals selected from the group consisting of sodium, potassium, magnesium, calcium, strontium, barium, manganese, cobalt, nickel, copper, lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, and bismuth, and the curing agent (C) contains dicyandiamide. By adopting such an embodiment, the storage stability and reactivity of the resulting epoxy resin composition can be greatly enhanced. Furthermore, in the embodiment of (3), it is more preferable that the metal constituting the metal (b2) includes one or more metals selected from the group consisting of sodium, potassium, and cesium, and one or more metals selected from the group consisting of nickel, lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, and bismuth. Including one or more of the above-mentioned specific metals as the metal constituting the metal (b2) can more significantly enhance the storage stability and reactivity.

[0099] The above (4) is an embodiment in which a primary aliphatic carboxylic acid and a secondary aliphatic carboxylic acid and / or the tertiary aliphatic carboxylic acid are used in combination as the compound (b1), the metal (b2) comprises at least one selected from the group consisting of sodium, potassium, and cesium, and the curing agent (C) contains dicyandiamide. By adopting such an embodiment, the storage stability and reactivity of the resulting epoxy resin composition can be greatly enhanced. When the primary aliphatic carboxylic acid and the secondary aliphatic carboxylic acid and / or the tertiary aliphatic carboxylic acid are used in combination as the compound (b1), the stability of the resulting epoxy resin composition can be more significantly enhanced. Although the detailed mechanism by which such an effect is obtained is unknown, it is thought that the primary aliphatic carboxylic acid surrounds the surface of the metal complex obtained by the coordination of a metal cation derived from the metal (b2) described later with the secondary aliphatic carboxylic acid and / or the tertiary aliphatic carboxylic acid, thereby improving stability compared to when the carboxylic acids are used alone. When a primary aliphatic carboxylic acid and a secondary aliphatic carboxylic acid and / or a tertiary aliphatic carboxylic acid are used in combination as the carboxylic acids, it is preferable to use a carboxylic acid with an acid dissociation constant (pKa) of 5.0 or less as the primary aliphatic carboxylic acid. Also, from a similar viewpoint, it is preferable that the number of carbon atoms in the primary aliphatic carboxylic acid is 2 to 10. Preferred specific examples of the primary carboxylic acid in this embodiment include hexanoic acid and octanoic acid. Furthermore, it is preferable to use 2-ethylhexanoic acid as the secondary aliphatic carboxylic acid and neodecanoic acid as the tertiary aliphatic carboxylic acid. In addition, in this embodiment, from the viewpoint of achieving a high degree of both storage stability and curability (reactivity), it is preferable that the amount of primary aliphatic carboxylic acid used is such that the carboxyl groups of the carboxylic acid are in the range of 0.3 to 10 moles, more preferably in the range of 0.4 to 8 moles, even more preferably in the range of 0.5 to 6 moles, and particularly preferably in the range of 0.5 to 3 moles, per mole of metal atoms in the metal (b2).Furthermore, from a similar viewpoint, in this embodiment, the total amount of carboxyl groups from the secondary aliphatic carboxylic acid and the tertiary aliphatic carboxylic acid is preferably 0.1 to 5.0 moles, more preferably 0.5 to 3.0 moles, and particularly preferably 0.5 to 2.0 moles, per mole of carboxyl groups from the primary aliphatic carboxylic acid.

[0100] The epoxy resin composition according to this embodiment preferably does not contain imidazoles. Here, "does not contain" means that they are intentionally omitted from the epoxy resin composition, and does not mean that impurity levels of contamination are eliminated. Also, here, "imidazoles" refers to compounds containing an imidazole ring structure. The absence of imidazoles in the epoxy resin composition can improve its latent properties.

[0101] <Other Resins> Depending on the intended use and performance, other thermosetting resins and thermoplastic resins may be used in combination with the epoxy resin composition according to this embodiment, to the extent that they do not impair the effects of this embodiment.

[0102] Other thermosetting resins include, for example, vinyl benzyl compounds and acrylic compounds. When using other thermosetting resins as described above, the amount used is not particularly limited as long as it does not hinder the effects of this embodiment, but it is preferably in the range of 1 to 50 parts by mass per 100 parts by mass of the epoxy resin composition.

[0103] Furthermore, various vinyl polymers may be used as other resins. Examples of these vinyl polymers include homopolymers or copolymers thereof of vinyl compounds such as polyhydroxystyrene, polystyrene, polyvinylnaphthalene, polyvinylanthracene, polyvinylcarbazole, polyindene, polyacenaphthylene, polynorbornene, polycyclodecene, polytetracyclododecene, polynortricycline, and poly(meth)acrylate.

[0104] The thermoplastic resins mentioned above refer to resins that can be melt-molded by heating. Specific examples include polyethylene resin, polypropylene resin, polystyrene resin, rubber-modified polystyrene resin, acrylonitrile-butadiene-styrene (ABS) resin, acrylonitrile-styrene (AS) resin, polymethyl methacrylate (PMMA) resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyethylene terephthalate resin, ethylene vinyl alcohol resin, cellulose acetate resin, ionomer resin, polyacrylonitrile resin, polyamide resin, polyacetal resin, polybutylene terephthalate resin, polylactic acid resin, polyphenylene ether resin, modified polyphenylene ether resin, polycarbonate resin, polysulfone resin, polyphenylene sulfide (PPS) resin, polyetherimide resin, polyethersulfone resin, polyarylate resin, thermoplastic polyimide resin, polyamideimide resin, polyetheretherketone resin, polyketone resin, liquid crystal polyester resin, fluororesin, syndiotactic polystyrene resin, and cyclic polyolefin resin. These thermoplastic resins can be used individually or in combination of two or more. When the epoxy resin composition of this embodiment contains the thermoplastic resin, the amount used is not particularly limited as long as it does not hinder the effects of this embodiment, but it is preferably in the range of 1 to 50 parts by mass per 100 parts by mass of the epoxy resin composition.

[0105] <Other Components> The epoxy resin composition of this embodiment may further contain, as needed, curing accelerators, non-halogenated flame retardants, fillers, fibrous substrates, organic solvents, additives, etc., to the extent that they do not impair the effects of the present invention. The order of compounding when manufacturing the epoxy resin composition is not particularly limited as long as it is a method that achieves the effects of the present invention. The following describes materials that can be contained in the epoxy resin composition of this embodiment.

[0106] (Curing accelerator) The epoxy resin composition of this embodiment may contain a curing accelerator that does not belong to curing agent (B) or curing agent (C). Various curing accelerators can be used, but examples include urea compounds, phosphorus compounds, tertiary amines, Lewis acids, amine complex salts, imidazoles, etc.

[0107] Examples of the urea compounds include p-chlorophenyl-N,N-dimethylurea, 3-phenyl-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-N,N-dimethylurea, and N-(3-chloro-4-methylphenyl)-N',N'-dimethylurea.

[0108] Examples of the phosphorus compounds include alkylphosphines such as ethylphosphine and butylphosphine, primary phosphines such as phenylphosphine; dialkylphosphines such as dimethylphosphine and dipropylphosphine; secondary phosphines such as diphenylphosphine and methylethylphosphine; and tertiary phosphines such as trimethylphosphine, triethylphosphine, and triphenylphosphine.

[0109] Examples of the aforementioned tertiary amines include triethylamine, N,N-dimethylbenzylamine, N,N-diethylbenzylamine, 1,8-diazabicyclo[5.4.0]undecene, and 1,4-diazabicyclo[2.2.2]octane.

[0110] Examples of the Lewis acid include complexes of boron halides and bases, such as boron trifluoride-piperidine complex, boron trifluoride-monoethylamine complex, boron trifluoride-triethanolamine complex, and boron trichloride-octylamine complex.

[0111] Examples of the amine complex salts include boron trifluoride monoethylamine complex, boron trifluoride diethylamine complex, boron trifluoride isopropylamine complex, boron trifluoride chlorophenylamine complex, boron trifluoride benzylamine complex, boron trifluoride aniline complex, or mixtures thereof, and other boron trifluoride complexes.

[0112] Examples of the imidazoles mentioned above include those listed in the section "Compounds having one or more heteroatoms selected from the group consisting of nitrogen, oxygen, and phosphorus in their molecule (b1)".

[0113] When the epoxy resin composition of this embodiment is used as an adhesive, urea compounds, particularly 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), are preferred due to their excellent workability and low-temperature curing properties. When used as a semiconductor encapsulating material, triphenylphosphine is preferred among phosphorus compounds, and 1,8-diazabicyclo-[5.4.0]-undecene (DBU) is preferred among tertiary amines due to their excellent curability, heat resistance, electrical properties, and moisture resistance reliability.

[0114] (Non-halogen flame retardant) When the epoxy resin composition of this embodiment is used in applications requiring high flame retardancy, a non-halogen flame retardant that substantially does not contain halogen atoms may be added.

[0115] Examples of the non-halogenated flame retardants include phosphorus-based flame retardants, nitrogen-based flame retardants, silicone-based flame retardants, inorganic flame retardants, and organometallic salt-based flame retardants. There are no restrictions on their use, and they can be used individually or in combination of two or more types.

[0116] The phosphorus-based flame retardant can be either an inorganic compound or an organophosphorus compound. Examples of the inorganic compound 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.

[0117] Furthermore, it is preferable that the red phosphorus is surface-treated to prevent hydrolysis and the like. Examples of surface treatment methods include (i) coating with an inorganic compound such as magnesium hydroxide, aluminum hydroxide, zinc hydroxide, titanium hydroxide, bismuth oxide, bismuth hydroxide, bismuth nitrate, or a mixture thereof; (ii) coating with a mixture of an inorganic compound such as magnesium hydroxide, aluminum hydroxide, zinc hydroxide, titanium hydroxide, and a thermosetting resin such as phenolic resin; and (iii) double coating with a thermosetting resin such as phenolic resin on top of a coating of an inorganic compound such as magnesium hydroxide, aluminum hydroxide, zinc hydroxide, titanium hydroxide, etc.

[0118] Examples of the aforementioned organophosphorus compounds include general-purpose organophosphorus compounds such as phosphate ester compounds, phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phospholane compounds, and organic nitrogen-containing phosphorus compounds, as well as 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.

[0119] The amount of phosphorus-based flame retardant to be blended is appropriately selected depending on the type of phosphorus-based flame retardant, the other components of the resin composition, and the desired degree of flame retardancy. For example, in 100 parts by mass of the epoxy resin composition of this embodiment, when red phosphorus is used as a non-halogen-based flame retardant, it is preferable to blend it in the range of 0.1 to 2.0 parts by mass. Similarly, when an organophosphorus compound is used, it is preferable to blend it in the range of 0.1 to 10.0 parts by mass, and more preferably in the range of 0.5 to 6.0 parts by mass.

[0120] When using the phosphorus-based flame retardant, hydrotalcite, magnesium hydroxide, boron compounds, zirconium oxide, black dyes, calcium carbonate, zeolite, zinc molybdate, activated carbon, etc., may be used in combination with the phosphorus-based flame retardant.

[0121] Examples of the nitrogen-based flame retardants include triazine compounds, cyanuric acid compounds, isocyanuric acid compounds, and phenothiazines, among which triazine compounds, cyanuric acid compounds, and isocyanuric acid compounds are preferred.

[0122] Examples of the triazine compounds include melamine, acetoganamine, benzoguanamine, melon, melam, succinoguanamine, ethylenedimelamine, polyphosphate melamine, triguanamine, etc., as well as (1) sulfate aminotriazine compounds such as guanylmelamine sulfate, melem sulfate, and melam sulfate; (2) co-condensates of phenols such as phenol, cresol, xylenol, butylphenol, and nonylphenol, and melamines such as melamine, benzoguanamine, acetoganamine, and formuanamine, and formaldehyde; (3) mixtures of the co-condensates of (2) and phenol resins such as phenol-formaldehyde condensates; and (4) the above (2) and (3) further modified with tung oil, isomerized linseed oil, etc.

[0123] Examples of the cyanuric acid compound include cyanuric acid and melamine cyanurate.

[0124] The amount of nitrogen-based flame retardant to be blended is appropriately selected depending on the type of nitrogen-based flame retardant, the other components of the resin composition, and the desired degree of flame retardancy. For example, in the epoxy resin composition of this embodiment, it is preferable to blend it in the range of 0.05 to 10 parts by mass, and more preferably in the range of 0.1 to 5 parts by mass.

[0125] When using the aforementioned nitrogen-based flame retardant, metal hydroxides, molybdenum compounds, etc., may be used in combination.

[0126] The silicone-based flame retardant can be any organic compound containing silicon atoms, and examples include silicone oil, silicone rubber, and silicone resin. The amount of the silicone-based flame retardant is appropriately selected depending on the type of silicone-based flame retardant, the other components of the resin composition, and the desired degree of flame retardancy. For example, it is preferable to include it in the range of 0.05 to 20 parts by mass in 100 parts by mass of the resin composition containing the non-halogen-based flame retardant and all other fillers and additives. Furthermore, when using the silicone-based flame retardant, molybdenum compounds, alumina, etc., may be used in combination.

[0127] Examples of the inorganic flame retardants include metal hydroxides, metal oxides, metal carbonate compounds, metal powders, boron compounds, and low-melting-point glass.

[0128] Examples of the aforementioned metal hydroxides include aluminum hydroxide, magnesium hydroxide, dolomite, hydrotalcite, calcium hydroxide, barium hydroxide, and zirconium hydroxide.

[0129] Examples of the aforementioned metal oxides include zinc molybdate, molybdenum trioxide, zinc stannate, tin oxide, aluminum oxide, iron oxide, titanium oxide, manganese oxide, zirconium oxide, zinc oxide, molybdenum oxide, cobalt oxide, bismuth oxide, chromium oxide, nickel oxide, copper oxide, and tungsten oxide.

[0130] Examples of the aforementioned metal carbonate compounds include zinc carbonate, magnesium carbonate, calcium carbonate, barium carbonate, basic magnesium carbonate, aluminum carbonate, iron carbonate, cobalt carbonate, and titanium carbonate.

[0131] Examples of the aforementioned metal powders include aluminum, iron, titanium, manganese, zinc, molybdenum, cobalt, bismuth, chromium, nickel, copper, tungsten, and tin.

[0132] Examples of the boron compounds mentioned above include zinc borate, zinc metaborate, barium metaborate, boric acid, borax, and boric acid esters.

[0133] The low melting point glass is, for example, Seeply manufactured by Air Brown Co., Ltd., hydrated glass SiO ２ - MgO - H ２ O, PbO - B ２ O ３ system, ZnO - P ２ O5 - MgO system, P ２ O ５ - B ２ O ３ - PbO - MgO system, P - Sn - O - F system, PbO - V ２ O ５ - TeO ２ [[ID=S24]] system, Al ２ O ３ - H ２ O system, lead borosilicate system and other glassy compounds can be mentioned.

[0134] The blending amount of the inorganic flame retardant is appropriately selected according to the type of the inorganic flame retardant, other components of the resin composition, and the desired degree of flame retardancy. For example, in 100 parts by mass of the epoxy resin composition containing all of the non - halogen - based flame retardant and the other fillers and additives, it is preferably blended within the range of 0.05 parts by mass to 20 parts by mass, and more preferably blended within the range of 0.5 parts by mass to 15 parts by mass.

[0135] The organometallic salt - based flame retardant includes, for example, ferrocene, acetylacetonate metal complex, organometallic carbonyl compound, organic cobalt salt compound, organic sulfonic acid metal salt, and compounds in which metal atoms are ion - bonded and / or coordinated with aromatic compounds and / or heterocyclic compounds.

[0136] The blending amount of the organometallic salt - based flame retardant is appropriately selected according to the type of the organometallic salt - based flame retardant, other components of the resin composition, and the desired degree of flame retardancy. For example, in 100 parts by mass of the epoxy resin composition containing all of the non - halogen - based flame retardant and the other fillers and additives, it is preferably blended within the range of 0.005 parts by mass to 10 parts by mass.

[0137] (Filler) The epoxy resin composition of the present embodiment may contain a filler. Examples of the filler include inorganic fillers and organic fillers. Examples of the inorganic filler include inorganic fine particles and the like.

[0138] Examples of the aforementioned inorganic fine particles include, for example, alumina, magnesia, titania, zirconia, silica (quartz, fumed silica, precipitated silica, anhydrous silicic acid, fused silica, crystalline silica, ultrafine amorphous silica, etc.) which have excellent heat resistance; boron nitride, aluminum nitride, aluminum oxide, titanium oxide, magnesium oxide, zinc oxide, silicon oxide, diamond, etc. which have excellent thermal conductivity; metal fillers and / or metal-coated fillers using elemental metals or alloys (e.g., iron, copper, magnesium, aluminum, gold, silver, platinum, zinc, manganese, stainless steel, etc.) which have excellent electrical conductivity; and minerals such as mica, clay, kaolin, talc, zeolite, wollastonite, smectite, etc., as well as potassium titanate, magnesium sulfate, sepiolite, zonolite, etc. which have excellent barrier properties. Examples of photocatalytic materials include: ion, aluminum borate, calcium carbonate, titanium dioxide, barium sulfate, zinc oxide, and magnesium hydroxide; materials with high refractive index include barium titanate, zirconia oxide, and titanium dioxide; materials exhibiting photocatalytic properties include photocatalytic metals such as titanium, cerium, zinc, copper, aluminum, tin, indium, phosphorus, carbon, sulfur, ruthenium, nickel, iron, cobalt, silver, molybdenum, strontium, chromium, barium, and lead, as well as composites of the aforementioned metals and their oxides; materials with excellent wear resistance include metals such as silica, alumina, zirconia, and magnesium oxide, and their composites and oxides; materials with excellent conductivity include metals such as silver and copper, tin oxide, and indium oxide; materials with excellent insulation properties include silica; and materials with excellent ultraviolet shielding properties include titanium dioxide and zinc oxide. These inorganic fine particles can be selected as appropriate depending on the application, and may be used individually or in combination of multiple types. Furthermore, since the inorganic fine particles have various properties other than those listed as examples, they should be selected as appropriate for the application.

[0139] When using silica as the inorganic fine particles, for example, there are no particular limitations, and known silica fine particles such as powdered silica or colloidal silica can be used. Examples of commercially available powdered silica fine particles include silica fine particles manufactured by Nippon Aerosil Co., Ltd. (product names: Aerosil 50, 200), silica fine particles manufactured by AGC Inc. (product names: Sildex H31, H32, H51, H52, H121, H122), silica fine particles manufactured by Nippon Silica Industry Co., Ltd. (product names: E220A, E220), silica fine particles manufactured by Fuji Silysia Chemical Co., Ltd. (product name: SYLYSIA470), and silica fine particles manufactured by Nippon Sheet Glass Co., Ltd. (product name: SG Flake).

[0140] Furthermore, commercially available colloidal silica can be found in, for example, the methanol silica sol manufactured by Nissan Chemical Corporation (product names: IPA-ST, MEK-ST, NBA-ST, XBA-ST, DMAC-ST, ST-UP, ST-OUP, ST-20, ST-40, ST-C, ST-N, ST-O, ST-50, ST-OL).

[0141] As the silica nanoparticles, silica nanoparticles with a modified surface may be used. For example, silica nanoparticles that have been surface-treated with a reactive silane coupling agent having a hydrophobic group, or silica nanoparticles that have been modified with a compound having a (meth)acryloyl group, are examples. Examples of commercially available powdered silica modified with a compound having a (meth)acryloyl group include silica manufactured by Nippon Aerosil Co., Ltd. (product names: Aerosil RM50, R711), and examples of commercially available colloidal silica modified with a compound having a (meth)acryloyl group include colloidal silica manufactured by Nissan Chemical Industries, Ltd. (product name: MIBK-SD).

[0142] The shape of the silica nanoparticles is not particularly limited, and spherical, hollow, porous, rod-shaped, plate-shaped, fibrous, or irregularly shaped nanoparticles can be used. The primary particle diameter of the silica nanoparticles is preferably in the range of 5 to 200 nm.

[0143] As the titanium dioxide nanoparticles, not only extender pigments but also ultraviolet light-responsive photocatalysts can be used, such as anatase-type titanium dioxide, rutile-type titanium dioxide, and brookite-type titanium dioxide. Furthermore, particles designed to respond to visible light by doping different elements into the crystal structure of titanium dioxide can also be used. Suitable elements for doping titanium dioxide include anionic elements such as nitrogen, sulfur, carbon, fluorine, and phosphorus, and cationic elements such as chromium, iron, cobalt, and manganese. In terms of form, powder, sol dispersed in an organic solvent or water, or slurry can be used. Examples of commercially available powdered titanium dioxide nanoparticles include Aerosil (product name: P-25) manufactured by Nippon Aerosil Co., Ltd., and titanium dioxide nanoparticles (product name: ATM-100) manufactured by Teika Co., Ltd. Examples of commercially available slurry-type titanium dioxide nanoparticles include titanium dioxide nanoparticles (product name: TKD-701) manufactured by Teika Co., Ltd.

[0144] Examples of organic fillers include polyacrylate particles, co-acryl-type polyacrylate particles, polystyrene particles, acrylic-styrene copolymer particles, polypropylene particles, polyethylene particles, and the like.

[0145] (Fibrous Substrate) The epoxy resin composition of this embodiment may further contain a fibrous substrate. The fibrous substrate is not particularly limited, but those used in fiber-reinforced resins are preferred, and examples include inorganic fibers and organic fibers.

[0146] Examples of the inorganic fibers include carbon fibers, glass fibers, boron fibers, alumina fibers, silicon carbide fibers, as well as carbon fibers, activated carbon fibers, graphite fibers, tungsten carbide fibers, silicon carbide fibers (silicon carbide fibers), ceramic fibers, natural fibers, mineral fibers such as basalt, boron nitride fibers, boron carbide fibers, and metal fibers. Examples of the metal fibers include aluminum fibers, copper fibers, brass fibers, stainless steel fibers, and steel fibers.

[0147] Examples of the aforementioned organic fibers include synthetic fibers made from resin materials such as polybenzazole, aramid, PBO (poly-p-phenylenebenzoxazole), polyphenylene sulfide, polyester, acrylic, polyamide, polyolefin, polyvinyl alcohol, and polyarylate; natural fibers such as cellulose, pulp, cotton, wool, and silk; and regenerated fibers such as proteins, polypeptides, and alginic acid.

[0148] Among these, carbon fibers and glass fibers are preferred because they have a wide range of industrial applications. The fibrous substrate can be used alone or in combination of two or more types.

[0149] The fibrous matrix may be an aggregate of fibers, and the fibers may be continuous or discontinuous, and may be woven or unwoven. It may also be a bundle of fibers aligned in one direction, or a sheet made of arranged bundles of fibers. Furthermore, it may be a three-dimensional shape with thickness given to the aggregate of fibers.

[0150] (Organic Solvents) The epoxy resin composition of this embodiment may contain organic solvents from the viewpoint of adjusting the solid content and viscosity of the resin composition. Examples of organic solvents that can be used as other components include the "organic solvent corresponding to compound (b1)" and the "organic solvent not corresponding to compound (b1)" described in the "curing agent (B)" section above. These organic solvents can be used individually or in combination of two or more.

[0151] (Additives) The epoxy resin composition according to this embodiment may contain additives. When the epoxy resin composition of this embodiment contains additives, other properties such as rigidity and dimensional stability are improved in the resulting cured product. Examples of additives that can be added include plasticizers, antioxidants, UV absorbers, light stabilizers and other stabilizers, antistatic agents, conductivity imparters, stress relievers, mold release agents, crystallization accelerators, hydrolysis inhibitors, lubricants, impact imparters, sliding properties improvers, compatibilizers, nucleating agents, strengthening agents, reinforcing agents, flow regulators, dyes, sensitizers, coloring pigments, rubbery polymers, thickeners, anti-settling agents, anti-sagging agents, defoaming agents, coupling agents, rust inhibitors, antibacterial and antifungal agents, antifouling agents, conductive polymers, etc.

[0152] The epoxy resin composition according to this embodiment exhibits excellent storage stability and reactivity, and can therefore be used in various applications where it is cured and used as is, specifically, paints, electrical and electronic materials, adhesives, substrate materials, molded products, and the like. In addition to the above applications, it can also be suitably used in fiber-reinforced composite materials and fiber-reinforced resin molded products.

[0153] <Method for Manufacturing the Epoxy Resin Composition> The method for manufacturing the epoxy resin composition of this embodiment is not particularly limited and can be manufactured by known methods. Specifically, for example, a method of manufacturing by mixing each component can be used. The mixing method is not particularly limited and may be a paint shaker, disperser, roll mill, bead mill, ball mill, attritor, sand mill, bead mill, etc. Furthermore, there is no particular restriction on the mixing order of each component contained in the epoxy resin composition. The epoxy resin (A) and curing agent (B) may be mixed first and then mixed with other components, or the epoxy resin (A), curing agent (B), and other components may be mixed simultaneously to prepare the composition.

[0154] ≪Cured Product≫ The cured product of this embodiment is the cured product of the epoxy resin composition of this embodiment described above. The method for obtaining a cured product from the epoxy resin composition of this embodiment can be the same as that for general epoxy resin compositions, and for example, the heating temperature conditions can be appropriately selected depending on the application. For example, one method is to heat the epoxy resin composition of this embodiment in a temperature range of about 50 to 250°C. General methods for molding the composition can also be used.

[0155] The cured product of this embodiment can be suitably used, for example, as a heat-resistant component or an electronic component. In particular, it can be suitably used as a prepreg, circuit board, semiconductor encapsulant, semiconductor device, build-up film, build-up substrate, adhesive, and resist material. It can also be suitably used as a matrix resin for fiber-reinforced resins and is particularly suitable as a high-heat-resistant prepreg. Furthermore, the resin contained in the epoxy resin composition exhibits excellent solubility in various solvents, making it possible to manufacture paints. The heat-resistant components and electronic components thus obtained can be suitably used in a variety of applications, including, but are not limited to, industrial machine parts, general machine parts, automobile, railway, and vehicle parts, aerospace-related parts, electronic and electrical components, building materials, containers and packaging materials, household goods, sports and leisure goods, wind turbine enclosures, etc.

[0156] Next, the present invention will be specifically described with reference to examples and comparative examples, but in the following, "parts" and "%" refer to mass unless otherwise specified.

[0157] <<Preparation of curing agent (b)>> (Synthesis example 1: Preparation of liquid curing agent (1)) 318 g of 2-ethylhexanoic acid and 100 g of cobalt hydroxide were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and the mixture was reacted at 130°C for 5 hours. Then, after dehydration under reduced pressure at 130°C, 134 g of petroleum hydrocarbon was added to obtain a 2-ethylhexanoic acid cobalt solution [liquid curing agent (1)]. The cobalt content in the obtained liquid curing agent (1) was 12% by mass, and the viscosity at 40°C was 100 mPa·s or less. The number of moles of 2-ethylhexanoic acid per mole of cobalt in liquid curing agent (1) was 2.05. The viscosity of the liquid curing agent was measured by the same method as described in <Storage Stability Evaluation> below.

[0158] (Synthesis Example 2: Preparation of Liquid Curing Agent (2)) 100 g of the 2-ethylhexanoate cobalt solution [liquid curing agent (1)] obtained in Synthesis Example 1 and 16.8 g of 1-methylimidazole were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and mixed at 50°C for 1 hour to obtain liquid curing agent (2). The viscosity of the obtained liquid curing agent (2) at 40°C was 100 mPa·s or less. The number of moles of 2-ethylhexanoate per mole of cobalt in liquid curing agent (2) was 2.05, and the total number of moles of 2-ethylhexanoate and 1-methylimidazole was 3.05.

[0159] (Synthesis Example 3: Preparation of Liquid Curing Agent (3)) In a flask equipped with a thermometer, stirrer, and reflux condenser, 1000 mL of distilled water, 211 g of 2-ethylhexanoic acid, and 58.4 g of sodium hydroxide were added and stirred at 30°C for 0.5 hours. Next, a solution of 212 g of nickel nitrate hexahydrate dissolved in 1000 mL of distilled water was added dropwise to the flask over 1 hour at 30°C. After the addition was complete, the mixture was stirred at 30°C for 1 hour to remove the distilled water. Next, the mixture was washed three times with distilled water to remove the distilled water and obtain the metal salt (a3). 100 g of the obtained metal salt (a3) ​​was dissolved in 100 g of hexane to obtain the liquid curing agent (3). The nickel content in the obtained liquid curing agent (3) was 8.5% by mass, and the viscosity at 40°C was 100 mPa·s or less. Furthermore, the number of moles of 2-ethylhexanoic acid per mole of nickel in the liquid curing agent (3) was 2.01.

[0160] (Synthesis Example 4: Preparation of Liquid Curing Agent (4)) 100 g of the liquid curing agent (3) obtained in Synthesis Example 3 and 11.8 g of 1-methylimidazole were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and mixed at 50°C for 1 hour to obtain liquid curing agent (4). The nickel content of the obtained liquid curing agent (4) was 7.6% by mass, and the viscosity at 40°C was 100 mPa·s or less. The number of moles of 2-ethylhexanoic acid per mole of nickel in the liquid curing agent (4) was 2.01, and the total number of moles of 2-ethylhexanoic acid and 1-methylimidazole was 3.01.

[0161] (Synthesis Example 5: Preparation of Liquid Curing Agent (5)) In a flask equipped with a thermometer, stirrer, and reflux condenser, 1000 mL of distilled water, 211 g of 2-ethylhexanoic acid, and 58.4 g of sodium hydroxide were added and stirred at 30°C for 0.5 hours. Next, a solution of 210 g of zinc sulfate heptahydrate dissolved in 1000 mL of distilled water was added dropwise to the flask over 1 hour at 30°C. After the addition was complete, the mixture was stirred at 30°C for 1 hour to remove the distilled water. Then, the mixture was washed three times with distilled water to remove the distilled water and obtain the liquid curing agent (5). The zinc content in the obtained liquid curing agent (5) was 18.6% by mass, and the viscosity at 40°C was 7800 mPa·s. The number of moles of 2-ethylhexanoic acid per mole of zinc in the liquid curing agent (5) was 2.01.

[0162] (Synthesis Example 6: Preparation of Liquid Curing Agent (6)) 100 g of the liquid curing agent (5) obtained in Synthesis Example 5 and 23.3 g of 1-methylimidazole were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and mixed at 50°C for 1 hour to obtain liquid curing agent (6). The zinc content of the obtained liquid curing agent (6) was 15.1% by mass, and the viscosity at 40°C was 6900 mPa·s. The number of moles of 2-ethylhexanoic acid per mole of zinc in the liquid curing agent (6) was 2.01, and the total number of moles of 2-ethylhexanoic acid and 1-methylimidazole was 3.01.

[0163] (Synthesis Example 7: Preparation of Liquid Curing Agent (7)) 100 g of the liquid curing agent (5) obtained in Synthesis Example 5, 23.3 g of 1-methylimidazole, and 17.5 g of picolinic acid were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and mixed at 50°C for 1 hour to obtain the metal salt (7). The zinc content of the obtained liquid curing agent (7) was 13.2% by mass, and the viscosity at 40°C was 8100 mPa·s. The number of moles of 2-ethylhexanoic acid per mole of zinc in the liquid curing agent (7) was 2.01, and the total number of moles of 2-ethylhexanoic acid, 1-methylimidazole, and picolinic acid was 3.51.

[0164] (Synthesis Example 8: Preparation of Liquid Curing Agent (8)) 100 g of the liquid curing agent (5) obtained in Synthesis Example 5 and 26.7 g of 1-vinylimidazole were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and mixed at 50°C for 1 hour to obtain liquid curing agent (8). The zinc content of the obtained liquid curing agent (8) was 14.6% by mass, and the viscosity at 40°C was 7100 mPa·s. The number of moles of 2-ethylhexanoic acid per mole of zinc in the liquid curing agent (8) was 2.01, and the total number of moles of 2-ethylhexanoic acid and 1-vinylimidazole was 3.01.

[0165] (Synthesis Example 9: Preparation of Liquid Curing Agent (9)) In a flask equipped with a thermometer, stirrer, and reflux condenser, 600 mL of distilled water, 122 g of 2-ethylhexanoic acid, and 33.9 g of sodium hydroxide were added and stirred at 30°C for 0.5 hours. Next, a solution of 100 g of calcium nitrate tetrahydrate dissolved in 300 mL of distilled water was added dropwise to the flask over 1 hour at 30°C. After the addition was complete, the mixture was stirred at 30°C for 1 hour to remove the distilled water and obtain the metal salt (a9). 100 g of the obtained metal salt (a9) was dissolved in 100 g of methanol to obtain the liquid curing agent (9). The calcium content of the obtained liquid curing agent (9) was 6.1% by mass, and the viscosity at 40°C was 100 mPa·s or less. Furthermore, the number of moles of 2-ethylhexanoic acid per mole of calcium in the liquid curing agent (9) was 2.0, and the total number of moles of 2-ethylhexanoic acid and methanol was 12.2.

[0166] (Synthesis Example 10: Preparation of Liquid Curing Agent (10)) 600 mL of distilled water, 163 g of neodecanoic acid, and 37.8 g of sodium hydroxide were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and the mixture was stirred at 30°C for 0.5 hours. Next, a solution of 100 g of strontium nitrate dissolved in 300 mL of distilled water was added dropwise to the flask over 1 hour at 30°C. After the addition was complete, the mixture was stirred at 30°C for 1 hour to remove the distilled water and obtain the metal salt (a10). 100 g of the obtained metal salt (a10) was dissolved in 100 g of methanol to obtain the liquid curing agent (10). The strontium content in the obtained liquid curing agent (10) was 10.2% by mass, and the viscosity at 40°C was 100 mPa·s or less. Furthermore, the number of moles of neodecanoic acid per mole of strontium in the liquid curing agent (10) was 2.0, and the total number of moles of neodecanoic acid and methanol was 15.5.

[0167] (Synthesis Example 11: Preparation of Liquid Curing Agent (11)) In a flask equipped with a thermometer, stirrer, and reflux condenser, 45.6 g of neodecanoic acid and 10.6 g of sodium hydroxide were reacted at 80°C for 1 hour, and then 20 g of manganese sulfate was added and reacted at 80°C. After washing with water, the mixture was dehydrated under reduced pressure at 130°C, and 37.5 g of benzyl alcohol was added to obtain the liquid curing agent (11). The manganese content in the obtained liquid curing agent (11) was 6.8% by mass, and the viscosity at 40°C was 8000 mPa·s. The number of moles of neodecanoic acid per mole of manganese in the liquid curing agent (11) was 2.0, and the total number of moles of neodecanoic acid and benzyl alcohol was 4.62.

[0168] (Synthesis Example 12: Preparation of Liquid Curing Agent (12)) 100 g of the liquid curing agent (11) obtained in Synthesis Example 11, 30.6 g of benzyl alcohol, and 30.6 g of picolinic acid were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and reacted at 50°C for 1 hour to obtain liquid curing agent (12). The manganese content of the obtained liquid curing agent (12) was 4.2% by mass, and the viscosity at 40°C was 610 mPa·s. The mole ratio of neodecanoic acid to 1 mole of manganese in the liquid curing agent (12) was 2.0, and the total number of moles of neodecanoic acid, benzyl alcohol, and picolinic acid was 8.91.

[0169] (Synthesis Example 13: Preparation of Liquid Curing Agent (13)) 144 g of 2-ethylhexanoic acid, 56 g of potassium hydroxide, and 300 mL of methanol were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser. The mixture was reacted at 50°C for 1 hour, and then the solvent was removed by distillation at 50°C to obtain the liquid curing agent (13). The potassium content of the obtained liquid curing agent (13) was 21% by mass, and the viscosity at 40°C was 5300 mPa·s. The number of moles of 2-ethylhexanoic acid per mole of potassium in the liquid curing agent (13) was 1.0.

[0170] (Synthesis Example 14: Preparation of Liquid Curing Agent (14)) 172 g of neodecanoic acid, 56 g of potassium hydroxide, and 300 mL of methanol were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser. The mixture was reacted at 50°C for 1 hour, and then the solvent was removed by distillation at 50°C to obtain the liquid curing agent (14). The potassium content of the obtained liquid curing agent (14) was 18% by mass, and the viscosity at 40°C was 8500 mPa·s. The number of moles of neodecanoic acid per mole of potassium in the liquid curing agent (14) was 1.0.

[0171] (Synthesis Example 15: Preparation of Liquid Curing Agent (15)) In a flask equipped with a thermometer, stirrer, and reflux condenser, 331 g of 2-ethylhexanoic acid and 125 g of bismuth oxide were reacted at 130°C. After dehydration under reduced pressure at 130°C, liquid curing agent (15) was obtained. The bismuth content in the obtained liquid curing agent (15) was 25% by mass, and the viscosity at 40°C was 1830 mPa·s. The number of moles of 2-ethylhexanoic acid per mole of bismuth in the liquid curing agent (15) was 4.3.

[0172] (Synthesis Example 16: Preparation of Liquid Curing Agent (16)) In a flask equipped with a thermometer, a stirrer, and a reflux condenser, 225 parts by mass of neodecanoic acid and 60 parts by mass of neodymium oxide were reacted at 130°C. After dehydration under reduced pressure at 130°C, 307 parts by mass of cyclohexane were added and mixed to obtain liquid curing agent (16). The neodymium content in the obtained liquid curing agent (16) was 8.8% by mass, and its viscosity at 40°C was 220 mPa·s. The mole ratio of neodecanoic acid to 1 mole of neodymium in the liquid curing agent (16) was 3.66.

[0173] (Synthesis Example 17: Preparation of Liquid Curing Agent (17)) 109 g of the liquid curing agent (13) obtained in Synthesis Example 13 and 100 g of the liquid curing agent (15) obtained in Synthesis Example 15 were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and mixed at 70°C for 1 hour to obtain liquid curing agent (17). The total potassium and bismuth content in the obtained liquid curing agent (17) was 22.9% by mass, and the viscosity at 40°C was 3300 mPa·s. The number of moles of 2-ethylhexanoic acid per mole of total potassium and bismuth in the liquid curing agent (17) was 1.56.

[0174] (Synthesis Example 18: Preparation of Liquid Curing Agent (18)) 174 g of the liquid curing agent (13) obtained in Synthesis Example 13 and 100 g of the liquid curing agent (15) obtained in Synthesis Example 15 were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and mixed at 70°C for 1 hour to obtain the metal salt (18). The potassium and bismuth content in the obtained metal salt (18) was 22.5% by mass, and the viscosity at 40°C was 3900 mPa·s. The number of moles of 2-ethylhexanoic acid per mole of total potassium and bismuth in the liquid curing agent (18) was 1.37.

[0175] (Synthesis Example 19: Preparation of Liquid Curing Agent (19)) 126 g of the liquid curing agent (14) obtained in Synthesis Example 14 and 100 g of the liquid curing agent (15) obtained in Synthesis Example 15 were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and mixed at 70°C for 1 hour to obtain liquid curing agent (19). The potassium and bismuth content in the obtained liquid curing agent (19) was 21.1% by mass, and the viscosity at 40°C was 6100 mPa·s. The number of moles of 2-ethylhexanoic acid and neodecanoic acid per mole of total potassium and bismuth in liquid curing agent (19) was 1.73.

[0176] (Synthesis Example 20: Preparation of Liquid Curing Agent (20)) 201 g of the liquid curing agent (14) obtained in Synthesis Example 14 and 100 g of the liquid curing agent (15) obtained in Synthesis Example 15 were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and mixed at 70°C for 1 hour to obtain the metal salt (20). The potassium and bismuth content in the obtained liquid curing agent (20) was 20.3% by mass, and the viscosity at 40°C was 7300 mPa·s. The number of moles of 2-ethylhexanoic acid and neodecanoic acid relative to 1 mole of potassium and bismuth in the liquid curing agent (20) was 1.55.

[0177] (Synthesis Example 21: Preparation of Liquid Curing Agent (21)) 89 g of the liquid curing agent (13) obtained in Synthesis Example 13 and 100 g of the liquid curing agent (16) obtained in Synthesis Example 16 were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and mixed at 70°C for 1 hour to obtain liquid curing agent (21). The potassium and neodymium content in the obtained metal salt (21) was 14.5% by mass, and the viscosity at 40°C was 1700 mPa·s. The number of moles of 2-ethylhexanoic acid and neodecanoic acid per 1 mole of total potassium and neodymium in the liquid curing agent (21) was 1.54.

[0178] (Synthesis Example 22: Preparation of Liquid Curing Agent (22)) 103 g of the liquid curing agent (14) obtained in Synthesis Example 14 and 100 g of the liquid curing agent (16) obtained in Synthesis Example 16 were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and mixed at 70°C for 1 hour to obtain liquid curing agent (22). The potassium and neodymium content in the obtained liquid curing agent (22) was 13.5% by mass, and the viscosity at 40°C was 2200 mPa·s. The number of moles of neodecanoic acid per mole of total potassium and neodymium in the liquid curing agent (22) was 1.72.

[0179] (Synthesis Example 23: Preparation of Liquid Curing Agent (23)) 100 g of the liquid curing agent (13) obtained in Synthesis Example 13 and 47 g of butanoic acid were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and mixed at 70°C for 1 hour to obtain liquid curing agent (23). The potassium content in the obtained liquid curing agent (23) was 14.2% by mass, and the viscosity at 40°C was 350 mPa·s. The number of moles of 2-ethylhexanoic acid and butanoic acid per mole of potassium in the liquid curing agent (23) was 2.0.

[0180] (Synthesis Example 24: Preparation of Liquid Curing Agent (24)) 100 g of the liquid curing agent (13) obtained in Synthesis Example 13 and 63 g of hexanoic acid were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and mixed at 70°C for 1 hour to obtain liquid curing agent (24). The potassium content in the obtained liquid curing agent (24) was 12.9% by mass, and the viscosity at 40°C was 300 mPa·s. The number of moles of 2-ethylhexanoic acid and hexanoic acid per mole of potassium in the liquid curing agent (24) was 2.0.

[0181] (Synthesis Example 25: Preparation of Liquid Curing Agent (25)) 100 g of the liquid curing agent (13) obtained in Synthesis Example 13, 78 g of octanoic acid, and 19 g of neodecanoic acid were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and mixed at 70°C for 1 hour to obtain liquid curing agent (25). The potassium content in the obtained liquid curing agent (25) was 10.7% by mass, and the viscosity at 40°C was 210 mPa·s. The number of moles of 2-ethylhexanoic acid, neodecanoic acid, and octanoic acid per mole of potassium in the liquid curing agent (25) was 2.2.

[0182] (Synthesis Example 26: Preparation of Liquid Curing Agent (26)) 100 g of the liquid curing agent (13) obtained in Synthesis Example 13, 85 g of nonanoic acid, and 19 g of neodecanoic acid were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and the mixture was stirred at 70°C for 1 hour to obtain liquid curing agent (26). The potassium content in the obtained liquid curing agent (26) was 10.3% by mass, and the viscosity at 40°C was 250 mPa·s. The mole ratio of 2-ethylhexanoic acid, neodecanoic acid, and nonanoic acid per mole of potassium in the liquid curing agent (26) was 2.2.

[0183] (Synthesis Example 27: Preparation of Liquid Curing Agent (27)) 100 g of the liquid curing agent (13) obtained in Synthesis Example 13, 31 g of hexanoic acid, and 19 g of neodecanoic acid were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and the mixture was stirred at 70°C for 1 hour to obtain liquid curing agent (27). The potassium content in the obtained liquid curing agent (27) was 14% by mass, and the viscosity at 40°C was 420 mPa·s. The number of moles of 2-ethylhexanoic acid, neodecanoic acid, and hexanoic acid per mole of potassium in the liquid curing agent (27) was 1.7.

[0184] (Synthesis Example 28: Preparation of Liquid Curing Agent (28)) 100 g of the liquid curing agent (13) obtained in Synthesis Example 13, 47 g of hexanoic acid, and 19 g of neodecanoic acid were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and mixed at 70°C for 1 hour to obtain liquid curing agent (28). The potassium content in the obtained liquid curing agent (28) was 12.7% by mass, and the viscosity at 40°C was 350 mPa·s. The number of moles of 2-ethylhexanoic acid, neodecanoic acid, and hexanoic acid per mole of potassium in the liquid curing agent (28) was 1.95.

[0185] <<Preparation of Epoxy Resin Composition>> (Example 1) An epoxy resin composition was obtained by mixing the epoxy resin ("EPICLON 850-S" (manufactured by DIC Corporation, epoxy equivalent: 188 g / equivalent)) and the liquid curing agent (2) obtained above in the mixing ratio shown in Table 1 below.

[0186] (Examples 2-6) Epoxy resin compositions were obtained using the same procedure as in Example 1, except that the type and amount of liquid curing agent were changed to those listed in Table 1.

[0187] (Examples 7-28) Epoxy resin compositions were obtained using the same procedure as in Example 1, except that the type and amount of liquid curing agent used in Example 1 were changed to those listed in Table 1, and a curing accelerator (dicyandiamide (DICY) ("DICY7," manufactured by Mitsubishi Chemical Corporation) was added.

[0188] (Comparative Example 1) An epoxy resin composition was obtained using the same procedure as in Example 1, except that the liquid curing agent (2) in Example 1 was changed to 1-methylimidazole.

[0189] (Comparative Example 2) An epoxy resin composition was obtained using the same procedure as in Example 7, except that the liquid curing agent (1) in Example 7 was not added.

[0190] <Evaluation> <Storage Stability Evaluation> The viscosity change of each epoxy resin composition obtained above was observed when stored at 50°C for 24 hours using the following measuring instrument. The viscosity at the start of measurement (formulation) was set to 100%, and the viscosity after 24 hours at 50°C was measured and calculated as the viscosity increase rate. Measuring instrument: TV-100E viscometer manufactured by Toki Sangyo Co., Ltd., measurement temperature: 40°C, preheating time: 1 minute, measurement time: 3 minutes (the value after 3 minutes was used). Note that a viscosity increase rate of 130% or less of the epoxy resin composition indicates excellent storage stability. The viscosity increase rate is preferably 120% or less, and more preferably 110% or less.

[0191] <Reactivity Evaluation, Heat Resistance Evaluation: DMA> Each epoxy resin composition obtained above was sandwiched between aluminum mirror plates (JIS H 4000 A1050P, manufactured by Engineering Test Service Co., Ltd.) with a silicone tube as a spacer, and heated and cured under predetermined curing conditions to obtain a cured product with a thickness of 0.8 mm. A 6 mm x 35 mm test piece was cut from the cured product, and the temperature at which the change in elastic modulus was maximized was evaluated as the glass transition temperature using a viscoelasticity measuring device (DMA: RSAII solid viscoelasticity measuring device, manufactured by Rheometric, Inc., tensile method: frequency 1 Hz, heating rate 3 °C / min). Note that a glass transition temperature of 90 °C or higher indicates excellent reactivity and heat resistance. The glass transition temperature of the curing agent is more preferably 140 °C or higher, and even more preferably 160 °C or higher.

[0192] <Adhesion Test (Room Temperature)> Each epoxy resin composition obtained above was applied to one of two cold-rolled steel sheets (SPCC-SD, manufactured by TP Giken Co., Ltd., 1.0 mm x 25 mm x 100 mm), glass beads (J-80, manufactured by Potters Barotini Co., Ltd.) were added as spacers, and the other SPCC-SD sheet was bonded to it (bonding area: 25 mm x 12.5 mm). This was then heat-cured under predetermined curing conditions to obtain an adhesion test specimen. The adhesion was evaluated by performing a tensile shear test using the adhesion test specimen. The test was conducted in accordance with JIS K 6850, and the maximum point stress at a measurement environment of 23°C was compared. Note that a maximum point stress of 7 MPa or higher indicates excellent adhesion. A maximum point stress of 10 MPa or higher is more preferable, and 12 MPa or higher is even more preferable.

[0193]

[0194] The epoxy resin compositions of Examples 1 to 28 exhibited superior storage stability and reactivity compared to the comparative examples. Furthermore, Examples 9 to 28, which contained dicyandiamide (DICY) and in which the metal (b2) was composed of potassium, calcium, strontium, manganese, bismuth, or neodymium, achieved an even higher balance of storage stability and reactivity. In particular, Examples 17 to 20, in which the metal (b2) was composed of potassium and bismuth, and Examples 21 to 22, in which it was composed of potassium and neodymium, showed particularly excellent storage stability and reactivity. In addition, Examples 23 to 24, in which the metal (b2) was composed of potassium and compound (b1) was a combination of primary and secondary aliphatic carboxylic acids, and Examples 25 to 28, in which compound (b1) was a combination of primary, secondary, and tertiary aliphatic carboxylic acids, also showed particularly excellent storage stability and reactivity.

Claims

1. An epoxy resin composition comprising an epoxy resin (A) and a curing agent (B), wherein the curing agent (B) contains a compound (b1) having one or more heteroatoms selected from the group consisting of nitrogen, oxygen, and phosphorus in its molecule, and a metal (b2) as raw materials, the compound (b1) includes carboxylic acids, and the content of the curing agent (B) is 0.1 to 15 parts by mass per 100 parts by mass of the epoxy resin (A).

2. The epoxy resin composition according to claim 1, wherein the viscosity of the curing agent (B) at 40°C is 20,000 mPa·s or less.

3. The epoxy resin composition according to claim 1, wherein the content of the curing agent (B) is 0.1 to 15 parts by mass as solid content with respect to 100 parts by mass of solid content of the epoxy resin (A).

4. The epoxy resin composition according to claim 1, wherein the amount of carboxyl groups of the carboxylic acids is 0.8 to 20 moles per mole of metal atoms in the metal (b2).

5. The epoxy resin composition according to claim 1, wherein the metal content in composition (B) is 1 to 30% by mass.

6. The epoxy resin composition according to claim 1, wherein the molecular weight of compound (b1) is 500 or less.

7. The epoxy resin composition according to claim 1, wherein the metal (b2) comprises one or more metals selected from the group consisting of potassium, cobalt, nickel, copper, and zinc.

8. The epoxy resin composition according to claim 1, further comprising a curing agent (C).

9. The epoxy resin composition according to claim 8, wherein the metal (b2) comprises one or more metals selected from the group consisting of sodium, potassium, magnesium, calcium, strontium, barium, manganese, cobalt, nickel, copper, lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, and bismuth, and the curing agent (C) is dicyandiamide.

10. The epoxy resin composition according to claim 9, wherein the metal (b2) comprises one or more metals selected from the group consisting of sodium, potassium, and cesium, and one or more metals selected from the group consisting of nickel, lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, and bismuth.

11. The epoxy resin composition according to claim 9, wherein the amount of curing agent (C) is such that the equivalent amount of active hydrogen of the amino groups in the cured product (C) is in the range of 0.1 to 1.5 per mole of epoxy groups in the epoxy resin (A).

12. The epoxy resin composition according to claim 1, wherein the curing agent (B) satisfies the relationship 1.5(X・n) ≤ Y・m (where X is the valence of the metal (b2), n is the amount of substance of the metal (b2), Y is the valence of the compound (b1), and m is the amount of substance of the compound (b1).

13. The epoxy resin composition according to claim 1, which does not contain imidazoles.

14. A cured product of an epoxy resin composition according to any one of claims 1 to 13.

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